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  • Public defence: 2025-08-21 09:15 H:son Holmdahlsalen, Uppsala
    Nihlén, Sandra
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Physiological and psychological aspects of fluid therapy in anaesthesia and intensive care medicine2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Intravenous fluid administration is commonly used for critically ill and perioperative patients, but increasing attention is being given to its potential negative effects. In these cases, balancing fluid needs for hemodynamic stability with avoiding fluid overload and organ damage is crucial.

    This thesis aimed to describe fluid administration practices in ICUs and postoperative care units in Sweden, focusing on how clinicians’ approach four key areas. It also sought to highlight the consequences of these practices and encourage clinicians to reconsider routine fluid prescriptions in both intensive care and perioperative settings.

    In Paper I, a prospective multicentre interventional cross-over study, we investigated if limiting the availability of standard-sized fluid bags of Ringer’s acetate and replacing them with smaller-sized fluid bags would affect the total amount of fluid administered to ICU patients (n=437) and the impact on morbidity or mortality. However, data did not support our hypothesis.

    Paper II is a retrospective, multicentre study examining fluid types given to ICU patients (n=241) in the post-resuscitation phase. We found that maintenance and drug fluids significantly exceeded resuscitative fluids, with patients receiving more maintenance fluids, drug diluents, and sodium than recommended.

    Paper III is a post-hoc analysis of Paper II data. We found that plasma urea's share of estimated plasma osmolality increases during fluid volume reduction and with higher osmolality, independent of nitrogen administration and renal function. This shift from ionic osmolytes to urea resembles patterns seen in estivating animals.

    Paper IV is a single-centre study examining the relationship between ADH levels, fluid administration, and urine output in postoperative major abdominal surgery patients (n=54). We found that elevated ADH levels did not predict urine output or oliguria, but hypotension did. Increased fluid administration did not normalize urine output after oliguria.

    List of papers
    1. Predictors of Postoperative Oliguria in Patients Going Through Major Abdominal Surgery: A Single Center Prospective Observational Study
    Open this publication in new window or tab >>Predictors of Postoperative Oliguria in Patients Going Through Major Abdominal Surgery: A Single Center Prospective Observational Study
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Anesthesiology and Intensive Care
    Research subject
    Medical Science
    Identifiers
    urn:nbn:se:uu:diva-552075 (URN)
    Available from: 2025-03-07 Created: 2025-03-07 Last updated: 2025-03-18
    2. Hidden sources of fluids, sodium and potassium in stabilised Swedish ICU patients: A multicentre retrospective observational study
    Open this publication in new window or tab >>Hidden sources of fluids, sodium and potassium in stabilised Swedish ICU patients: A multicentre retrospective observational study
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    2021 (English)In: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 38, no 6, p. 625-633Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: Fluid overload in ICU patients is associated with increased morbidity and mortality. Although studies report on optimisation of resuscitation fluids given to ICU patients, increasing evidence suggests that maintenance fluids and fluids used to administer drugs are important sources of fluid overload.

    OBJECTIVES: We aimed to evaluate the volume of maintenance fluids and electrolytes on overall fluid balance and their relation to mortality in stabilised ICU patients.

    DESIGN: Multicentre retrospective observational study.

    SETTING: Six mixed surgical and medical ICUs in Sweden.

    PATIENTS: A total of 241 adult patients who spent at least 7 days in the ICU during 2018.

    MAIN OUTCOME MEASURES: The primary endpoint was the volume of maintenance, resuscitation and drug diluent fluids administered on days 3 to 7 in the ICU. Secondary endpoints were to compare dispensed amounts of maintenance fluids and electrolytes with predicted requirements. We also investigated the effects of administered fluids and electrolytes on patient outcomes.

    RESULTS: During ICU days 3 to 7, 56.4% of the total fluids given were maintenance fluids, nutritional fluids or both, 25.4% were drug fluids and 18.1% were resuscitation fluids. Patients received fluids 1.29 (95% confidence interval 1.07 to 1.56) times their estimated fluid needs. Despite this, 93% of the cohort was treated with diuretics or renal replacement therapy. Patients were given 2.17 (1.57 to 2.96) times their theoretical sodium needs and 1.22 (0.75 to 1.77) times their potassium needs. The median [IQR] volume of fluid loss during the 5-day study period was 3742 [3156 to 4479] ml  day-1, with urine output the main source of fluid loss. Death at 90 days was not associated with fluid or electrolyte balance in this cohort.

    CONCLUSION: Maintenance and drug fluids far exceeded resuscitative fluids in ICU patients beyond the resuscitative phase. This excess fluid intake, in conjunction with high urinary output and treatment for fluid offload in almost all patients, suggests that a large volume of the maintenance fluids given was unnecessary.

    TRIAL REGISTRATION: ClinicalTrials.org (identifier: NCT03972475).

    Place, publisher, year, edition, pages
    Wolters Kluwer, 2021
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:uu:diva-427135 (URN)10.1097/EJA.0000000000001354 (DOI)000647705400008 ()33074941 (PubMedID)
    Available from: 2020-12-03 Created: 2020-12-03 Last updated: 2025-03-07Bibliographically approved
    3. The contribution of plasma urea to total osmolality during iatrogenic fluid reduction in critically ill patients
    Open this publication in new window or tab >>The contribution of plasma urea to total osmolality during iatrogenic fluid reduction in critically ill patients
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    2021 (English)In: Function, E-ISSN 2633-8823, Vol. 3, no 1Article in journal (Refereed) Published
    Abstract [en]

    Hyperosmolality is common in critically ill patients during body fluid volume reduction. It is unknown whether this is only a result of decreased total body water or an active osmole-producing mechanism similar to that found in aestivating animals, where muscle degradation increases urea levels to preserve water. We hypothesized that fluid volume reduction in critically ill patients contributes to a shift from ionic to organic osmolytes similar to mechanisms of aestivation. We performed a post-hoc analysis on data from a multicenter observational study in adult intensive care unit (ICU) patients in the postresuscitative phase. Fluid, electrolyte, energy and nitrogen intake, fluid loss, estimated glomerular filtration rate (eGFR), and estimated plasma osmolality (eOSM) were registered. Contributions of osmolytes Na+, K+, urea, and glucose to eOSM expressed as proportions of eOSM were calculated. A total of 241 patients were included. eOSM increased (median change 7.4 mOsm/kg [IQR−1.9–18]) during the study. Sodium's and potassium's proportions of eOSM decreased (P < .05 and P < .01, respectively), whereas urea's proportion increased (P < .001). The urea’s proportion of eOSM was higher in patients with negative vs. positive fluid balance. Urea's proportion of eOSM increased with eOSM (r = 0.63; adjusted for eGFR r = 0.80), but not nitrogen intake. In patients without furosemide and/or renal replacement therapy (n = 17), urea’s proportion of eOSM and eOSM correlated strongly (r = 0.92). Urea’s proportion of eOSM was higher in patients not surviving up to 90 d. In stabilized ICU patients, the contribution of urea to plasma osmolality increased during body water volume reduction, statistically independently of nitrogen administration and eGFR. The shift from ionic osmolytes to urea during body fluid volume reduction is similar to that seen in aestivating animals.

    Place, publisher, year, edition, pages
    Oxford University PressOxford University Press (OUP), 2021
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:uu:diva-460905 (URN)10.1093/function/zqab055 (DOI)000769818500005 ()35330925 (PubMedID)
    Available from: 2021-12-09 Created: 2021-12-09 Last updated: 2025-03-07Bibliographically approved
    4. Impact of resuscitation fluid bag size availability on volume of fluid administration in the intensive care unit
    Open this publication in new window or tab >>Impact of resuscitation fluid bag size availability on volume of fluid administration in the intensive care unit
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    2018 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 62, no 9, p. 1261-1266Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: Iatrogenic fluid overload is associated with increased mortality in the intensive care unit (ICU). Decisions on fluid therapy may, at times, be based on other factors than physiological endpoints. We hypothesized that because of psychological factors volume of available fluid bags would affect the amount of resuscitation fluid administered to ICU patients.

    METHODS: We performed a prospective intervention cross-over study at 3 Swedish ICUs by replacing the standard resuscitation fluid bag of Ringer's Acetate 1000 mL with 500 mL bags (intervention group) for 5 separate months and then compared it with the standard bag size for 5 months (control group). Primary endpoint was the amount of Ringer's Acetate per patient during ICU stay. Secondary endpoints were differences between the groups in cumulative fluid balance and change in body weight, hemoglobin and creatinine levels, urine output, acute kidney failure (measured as the need for renal replacement therapy, RRT) and 90-day mortality.

    RESULTS: Six hundred and thirty-five ICU patients were included (291 in the intervention group, 344 in the control group). There was no difference in the amount of resuscitation fluid per patient during the ICU stay (2200 mL [1000-4500 median IQR] vs 2245 mL [1000-5630 median IQR]), RRT rate (11 vs 9%), 90-day mortality (11 vs 10%) or total fluid balance between the groups. The daily amount of Ringer's acetate administered per day was lower in the intervention group (1040 (280-2000) vs 1520 (460-3000) mL; P = .03).

    CONCLUSIONS: The amount of resuscitation fluid administered to ICU patients was not affected by the size of the available fluid bags. However, altering fluid bag size could have influenced fluid prescription behavior.

    Keywords
    adverse effects, critical care, crystalloid solutions, fluid therapy, psychological factors
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:uu:diva-362676 (URN)10.1111/aas.13161 (DOI)000443673500011 ()29851027 (PubMedID)
    Available from: 2018-10-08 Created: 2018-10-08 Last updated: 2025-03-07Bibliographically approved
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  • Public defence: 2025-08-22 09:15 Häggsalen, Ångströmlaboratoriet, Uppsala
    Dramburg, Darius
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Algebra, Logic and Representation Theory.
    Higher representation infinite algebras from skew-group algebras: Higher preprojective gradings, Koszul gradings, and McKay quivers2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consist of five papers in the area of representation theory of algebras. The focus lies on higher representation infinite algebras and their higher preprojective algebras. We consider the case of a polynomial ring skewed by the action of a finite subgroup of the special linear group, and construct and classify higher preprojective structures on this skew-group algebra. This involves the construction of McKay quivers and gradings of these quivers.

    Paper I covers the easiest previously unknown case. We classify the finite abelian subgroups of the special linear group in dimension 3 such that the corresponding skew-group algebra is the higher preprojective algebra of a higher representation infinite algebra. We also describe the involved mutations of these algebras, and give a combinatorial description.

    Paper II is a generalisation of paper I to arbitrary dimensions. For each finite abelian subgroup of the special linear group in dimension n+1, we consider the possible higher preprojective structures on the corresponding skew-group algebra. These structures naturally fall into several mutation classes, and we identify these classes with the internal points of a lattice simplex. We show that this lattice simplex is the junior simplex of the group. Furthermore, we equip each mutation class with the structure of a finite distributive lattice and construct the minimal and maximal elements of these lattices.

    Papers III and IV deal with the case of finite non-abelian subgroups of the special linear group in dimension 3. For each group, we decide whether the skew-group algebra can be endowed the the structure of a higher preprojective algebra, and describe the resulting higher representation infinite algebras. We give detailed descriptions of the relevant McKay quivers and provide numerous examples and computations.

    Paper V investigates the interaction between a Koszul- and a higher preprojective grading on the same algebra. While the two gradings need not be related, we show that in most cases, the Koszul grading can be moved by an automorphism to another Koszul grading that forms a bigrading together with the higher preprojective grading. As a consequence we show that a basic higher hereditary algebra can be endowed with an (almost) Koszul grading if and only if its higher preprojective algebra can be endowed with a Koszul grading. We also show that higher Auslander-Platzeck-Reiten tilting preserves Koszulity.

    List of papers
    1. The 3-preprojective algebras of type Ã
    Open this publication in new window or tab >>The 3-preprojective algebras of type Ã
    2024 (English)In: Journal of Pure and Applied Algebra, ISSN 0022-4049, E-ISSN 1873-1376, Vol. 228, no 12, article id 107760Article in journal (Refereed) Published
    Abstract [en]

    Let G ≤ SLn+1(C) act on R = C[X1, . . . , Xn+1] by change of variables. Then, the skew-group algebra R* G is bimodule (n + 1)-Calabi-Yau. In certain circumstances, this algebra admits a locally finite-dimensional grading of Gorenstein parameter 1, in which case it is the (n + 1)-preprojective algebra of its n-representation infinite degree 0 piece, as defined in [10]. If the group G is abelian, the (n +1)-preprojective algebra is said to be of type Ã. For a given group G, it is not obvious whether R* G admits such a grading making it into an (n + 1)-preprojective algebra. We study the case when n = 2 and G is abelian. We give an explicit classification of groups such that R* G is 3-preprojective by constructing such gradings. This is possible as long as G is not a subgroup of SL2(C) and not C2 x C2. For a fixed G, the algebra R* G admits different 3-preprojective gradings, so we associate a type to a grading and classify all types. Then we show that gradings of the same type are related by a certain kind of mutation. This gives a classification of 2-representation infinite algebras of type Ã. The involved quivers are those arising from hexagonal dimer models on the torus, and the gradings we consider correspond to perfect matchings on the dimer, or equivalently to periodic lozenge tilings of the plane. Consequently, we classify these tilings up to flips, which correspond to the mutation we consider.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:uu:diva-535407 (URN)10.1016/j.jpaa.2024.107760 (DOI)001264739400001 ()
    Funder
    Wenner-Gren Foundations, WGF2022-0052
    Available from: 2024-07-30 Created: 2024-07-30 Last updated: 2025-04-23Bibliographically approved
    2. A classification of n-representation infinite algebras of type Ã
    Open this publication in new window or tab >>A classification of n-representation infinite algebras of type Ã
    (English)Manuscript (preprint) (Other academic)
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:uu:diva-554997 (URN)10.48550/arXiv.2409.06553 (DOI)
    Available from: 2025-04-22 Created: 2025-04-22 Last updated: 2025-04-23
    3. 2-representation infinite algebras from non-abelian subgroups of SL(3,C). Part I: Extensions of abelian groups
    Open this publication in new window or tab >>2-representation infinite algebras from non-abelian subgroups of SL(3,C). Part I: Extensions of abelian groups
    (English)Manuscript (preprint) (Other academic)
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:uu:diva-554998 (URN)
    Available from: 2025-04-22 Created: 2025-04-22 Last updated: 2025-05-02
    4. 2-representation infinite algebras from non-abelian subgroups of SL(3,C). Part II: Central extensions and exceptionals
    Open this publication in new window or tab >>2-representation infinite algebras from non-abelian subgroups of SL(3,C). Part II: Central extensions and exceptionals
    (English)Manuscript (preprint) (Other academic)
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:uu:diva-555719 (URN)
    Available from: 2025-05-02 Created: 2025-05-02 Last updated: 2025-05-06
    5. On compatibility of Koszul- and higher preprojective gradings
    Open this publication in new window or tab >>On compatibility of Koszul- and higher preprojective gradings
    (English)Manuscript (preprint) (Other academic)
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:uu:diva-554999 (URN)10.48550/arXiv.2411.13283 (DOI)
    Available from: 2025-04-22 Created: 2025-04-22 Last updated: 2025-04-23
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    UUThesis_Dramburg,D-2025
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  • Public defence: 2025-08-22 13:15 101121, Sonja Lyttkens, Uppsala
    Yu, Zhanwei
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    Selected Topics on Optimal Allocation and Configuration in Mobile Computing for 5G and Beyond2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation explores optimal allocation and configuration in mobile computing for 5G and beyond. As wireless technologies rapidly evolve, emerging technologies such as integrated terrestrial, aerial, and satellite networks (ITASNs), integrated sensing and communication (ISAC), reconfigurable intelligent surfaces (RIS), edge computing, AI-driven networking, cell-free multiple-input multiple-output (MIMO), movable antenna systems, and passively cooled base stations (PCBS) are reshaping network design. These innovations promise significant improvements in capacity, energy efficiency, and sustainability, but also introduce challenges in resource allocation and configuration.

    The bulk of this dissertation comprises five research papers that address key resource allocation and configuration problems for some of the evolving technologies. Paper I presents a novel framework for jointly optimizing RIS configuration and resource allocation in multi-cell networks. Paper II investigates content caching in edge computing, proposing a column generation-based approach for balancing cost and data freshness. Paper III examines renewable energy management in edge computing networks to minimize the carbon footprint while maintaining performance. Papers IV and V focus on thermal management in PCBS, with Paper IV developing an online reinforcement learning method for dynamic load allocation in a single base station and Paper V extending this approach to multi-cell scenarios with inter-cell interference and resource coupling.

    List of papers
    1. Resource Optimization With Interference Coupling in Multi-RIS-Assisted Multi-Cell Systems
    Open this publication in new window or tab >>Resource Optimization With Interference Coupling in Multi-RIS-Assisted Multi-Cell Systems
    2022 (English)In: IEEE OPEN JOURNAL OF VEHICULAR TECHNOLOGY, ISSN 2644-1330, Vol. 3, p. 98-110Article in journal (Refereed) Published
    Abstract [en]

    Deploying reconfigurable intelligent surface (RIS) to enhance wireless transmission is a promising approach. In this paper, we investigate large-scale multi-RIS-assisted multi-cell systems, where multiple RISs are deployed in each cell. Different from the full-buffer scenario, the mutual interference in our system is not known a priori, and for this reason we apply the load coupling model to analyze this system. The objective is to minimize the total resource consumption subject to user demand requirement by optimizing the reflection coefficients in the cells. The cells are highly coupled and the overall problem is non-convex. To tackle this, we first investigate the single-cell case with given interference, and propose a low-complexity algorithm based on the Majorization-Minimization method to obtain a locally optimal solution. Then, we embed this algorithm into an algorithmic framework for the overall multi-cell problem, and prove its feasibility and convergence to a solution that is at least locally optimal. Simulation results demonstrate the benefit of RIS in time-frequency resource utilization in the multi-cell system.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE)Institute of Electrical and Electronics Engineers (IEEE), 2022
    Keywords
    Interference, Wireless communication, NOMA, Couplings, Time-frequency analysis, Array signal processing, Vehicular and wireless technologies, Load coupling, multi-cell system, reconfigurable intelligent surface (RIS), resource allocation
    National Category
    Communication Systems Telecommunications
    Identifiers
    urn:nbn:se:uu:diva-473657 (URN)10.1109/OJVT.2022.3154725 (DOI)000782412500001 ()
    Funder
    Swedish Research Council, 2018-05247
    Available from: 2022-05-02 Created: 2022-05-02 Last updated: 2025-05-07Bibliographically approved
    2. Multi-cell content caching: Optimization for cost and information freshness
    Open this publication in new window or tab >>Multi-cell content caching: Optimization for cost and information freshness
    2024 (English)In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 247, article id 110420Article in journal (Refereed) Published
    Abstract [en]

    In multi-access edge computing (MEC) systems, there are multiple local cache servers caching contents to satisfy the users' requests, instead of letting the users download via the remote cloud server. In this paper, a multi -cell content scheduling problem (MCSP) in MEC systems is considered. Taking into account jointly the freshness of the cached contents and the traffic data costs, we study how to schedule content updates along time in a multi -cell setting. Different from single -cell scenarios, a user may have multiple candidate local cache servers, and thus the caching decisions in all cells must be jointly optimized. We first prove that MCSP is NP -hard, then we formulate MCSP using integer linear programming, by which the optimal scheduling can be obtained for small-scale instances. For problem solving of large scenarios, via a mathematical reformulation, we derive a scalable optimization algorithm based on repeated column generation. Our performance evaluation shows the effectiveness of the proposed algorithm in comparison to an off -the -shelf commercial solver and a popularity -based caching.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    Keywords
    Age of information, Caching, Multi-cell
    National Category
    Communication Systems
    Identifiers
    urn:nbn:se:uu:diva-532164 (URN)10.1016/j.comnet.2024.110420 (DOI)001235269000001 ()
    Funder
    Swedish Research Council, 2022-04123
    Available from: 2024-06-24 Created: 2024-06-24 Last updated: 2025-05-07Bibliographically approved
    3. Less Carbon Footprint in Edge Computing by Joint Task Offloading and Energy Sharing
    Open this publication in new window or tab >>Less Carbon Footprint in Edge Computing by Joint Task Offloading and Energy Sharing
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    2023 (English)In: IEEE Networking Letters, E-ISSN 2576-3156, Vol. 5, no 4, p. 245-249Article in journal (Refereed) Published
    Abstract [en]

    We address reducing carbon footprint (CF) in the context of edge computing. The carbon intensity of electricity supply largely varies spatially as well as temporally. We consider optimal task scheduling and offloading, as well as battery charging to minimize the total CF. We formulate this optimization problem as a mixed integer linear programming model. However, we demonstrate that, via a graph-based reformulation, the problem can be cast as a minimum-cost flow problem, and global optimum can be admitted in polynomial time. Numerical results using real-world data show that optimization can reduce up to 83.3% of the total CF.

    Place, publisher, year, edition, pages
    IEEE, 2023
    National Category
    Telecommunications
    Identifiers
    urn:nbn:se:uu:diva-555956 (URN)10.1109/lnet.2023.3286933 (DOI)2-s2.0-85188618692 (Scopus ID)
    Funder
    Swedish Research Council, 101086219
    Available from: 2025-05-07 Created: 2025-05-07 Last updated: 2025-05-07Bibliographically approved
    4. Learn to Stay Cool: Online Load Management for Passively Cooled Base Stations
    Open this publication in new window or tab >>Learn to Stay Cool: Online Load Management for Passively Cooled Base Stations
    2024 (English)In: 2024 IEEE Wireless Communications and Networking Conference, WCNC 2024, Institute of Electrical and Electronics Engineers (IEEE), 2024, p. 1-6Conference paper, Published paper (Refereed)
    Abstract [en]

    Passively cooled base stations (PCBSs) are highly relevant for achieving better efficiency in cost and energy. However, dealing with the thermal issue via load management, particularly for outdoor deployment of PCBS, becomes crucial. This is a challenge because the heat dissipation efficiency is subject to (uncertain) fluctuation over time. Moreover, load management is an online decision-making problem by its nature. In this paper, we demonstrate that a reinforcement learning (RL) approach, specifically Soft Actor-Critic (SAC), enables to make a PCBS stay cool. The proposed approach has the capability of adapting the PCBS load to the time-varying heat dissipation. In addition, we propose a denial and reward mechanism to mitigate the risk of overheating from the exploration such that the proposed RL approach can be implemented directly in a practical environment, i.e., online RL. Numerical results demonstrate that the learning approach can achieve as much as 88.6% of the global optimum. This is impressive, as our approach is used in an online fashion to perform decision-making without the knowledge of future heat dissipation efficiency, whereas the global optimum is computed assuming the presence of oracle that fully eliminates uncertainty. This paper pioneers the approach to the online PCBSs load management problem.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2024
    Series
    IEEE Wireless Communications and Networking Conference, ISSN 1525-3511
    Keywords
    Passive cooling, load management, deep reinforcement learning
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-539623 (URN)10.1109/WCNC57260.2024.10571225 (DOI)001268569304052 ()9798350303582 (ISBN)9798350303599 (ISBN)
    Conference
    IEEE Wireless Communications and Networking Conference (IEEE WCNC), April 21-24, 2024, Dubai, United Arab Emirates
    Funder
    Swedish Research CouncilEU, Horizon 2020
    Available from: 2024-10-02 Created: 2024-10-02 Last updated: 2025-05-07Bibliographically approved
    5. Online Learning for Intelligent Thermal Management of Interference-Coupled and Passively Cooled Base Stations
    Open this publication in new window or tab >>Online Learning for Intelligent Thermal Management of Interference-Coupled and Passively Cooled Base Stations
    2025 (English)In: IEEE Transactions on Machine Learning in Communications and Networking, E-ISSN 2831-316X, Vol. 3, p. 64-79Article in journal (Refereed) Published
    Abstract [en]

    Passively cooled base stations (PCBSs) have emerged to deliver better cost and energy efficiency. However, passive cooling necessitates intelligent thermal control via traffic management, i.e., the instantaneous data traffic or throughput of a PCBS directly impacts its thermal performance. This is particularly challenging for outdoor deployment of PCBSs because the heat dissipation efficiency is uncertain and fluctuates over time. What is more, the PCBSs are interference-coupled in multi-cell scenarios. Thus, a higher-throughput PCBS leads to higher interference to the other PCBSs, which, in turn, would require more resource consumption to meet their respective throughput targets. In this paper, we address online decision-making for maximizing the total downlink throughput for a multi-PCBS system subject to constraints related on operating temperature. We demonstrate that a reinforcement learning (RL) approach, specifically soft actor-critic (SAC), can successfully perform throughput maximization while keeping the PCBSs cool, by adapting the throughput to time-varying heat dissipation conditions. Furthermore, we design a denial and reward mechanism that effectively mitigates the risk of overheating during the exploration phase of RL. Simulation results show that our approach achieves up to 88.6% of the global optimum. This is very promising, as our approach operates without prior knowledge of future heat dissipation efficiency, which is required by the global optimum.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2025
    Keywords
    Reinforcement learning, interference, passive cooling, throughput maximization, thermal management
    National Category
    Telecommunications
    Identifiers
    urn:nbn:se:uu:diva-555954 (URN)10.1109/tmlcn.2024.3517619 (DOI)001487807300001 ()
    Funder
    Swedish Research Council, 2022-04123EU, European Research Council, 101086219
    Available from: 2025-05-07 Created: 2025-05-07 Last updated: 2025-05-23Bibliographically approved
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  • Public defence: 2025-08-22 13:15 H:son Holmdahlsalen, Uppsala
    Ahmad, Nouman
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Image Segmentation, Registration and Deep Regression: Methods for CT-based Large-Scale Body Composition Analysis2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Body composition refers to the amount and distribution of fat, muscle, bone, and other tissues in the body. It is associated with the risk of, for example, type 2 diabetes (T2D) and cardiovascular disease (CVD). Computed tomography (CT) is an imaging modality that provides detailed internal views, making it a valuable tool for body composition analysis.

    CT imaging, however, exposes the imaged subjects to ionizing radiation, which poses health risks. To mitigate this, limited-slice protocols have been adopted for body composition studies. The Swedish CArdioPulmonary bioImage Study (SCAPIS) and Impaired Glucose Tolerance microbiota study (IGT) cohorts employ a three single-slice CT imaging approach. These cohort studies allow detailed investigations of the relationships between body composition, T2D, and CVD.

    The primary aim of this thesis was to develop and evaluate different methods for detailed association studies of CT imaging and non-imaging data, applicable to large-scale body composition research. These methods have been employed to perform tasks such as image segmentation, image registration, voxel-wise association studies, deep regression, and classification.

    An automatic segmentation method for the quantification of anatomical structures such as the liver, spleen, skeletal muscle, bone marrow, and various adipose tissue depots based on fully convolutional networks was developed and evaluated. To enable voxel-wise association studies, image registration was performed to align images from different subjects to a common reference space.

    Additionally, deep learning-based convolutional neural networks were trained for image-driven regression tasks, predicting proof-of-concept measurements and more complex target variables properties such as age, BMI, and sex. In deep regression tasks, interpretability is important both to validate the model and to aid in the discovery of new associations between the image data and the target variable. To enable interpretability and trustworthiness, individual Gradient-weighted Class Activation Mapping (Grad-CAM) saliency maps were generated, deformed into a common reference space, and subsequently aggregated to produce cohort-level saliency maps. These maps highlight anatomical structures commonly associated with the predicted target (parameter) across the population. Furthermore, uncertainty quantification was employed to provide individual confidence intervals for each prediction, thereby estimating the quality of the model predictions.

    In summary, advanced image analysis methods suitable for large-scale body composition analysis have been developed and evaluated. In future research the developed methods can be used, one at a time or in combination, for detailed studies of associations between body composition and, for example, prevalent and incident cardiometabolic diseases and their risk factors.

    List of papers
    1. Automatic segmentation of large-scale CT image datasets for detailed body composition analysis.
    Open this publication in new window or tab >>Automatic segmentation of large-scale CT image datasets for detailed body composition analysis.
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    2023 (English)In: BMC Bioinformatics, E-ISSN 1471-2105, Vol. 24, no 1, article id 346Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: Body composition (BC) is an important factor in determining the risk of type 2-diabetes and cardiovascular disease. Computed tomography (CT) is a useful imaging technique for studying BC, however manual segmentation of CT images is time-consuming and subjective. The purpose of this study is to develop and evaluate fully automated segmentation techniques applicable to a 3-slice CT imaging protocol, consisting of single slices at the level of the liver, abdomen, and thigh, allowing detailed analysis of numerous tissues and organs.

    METHODS: The study used more than 4000 CT subjects acquired from the large-scale SCAPIS and IGT cohort to train and evaluate four convolutional neural network based architectures: ResUNET, UNET++, Ghost-UNET, and the proposed Ghost-UNET++. The segmentation techniques were developed and evaluated for automated segmentation of the liver, spleen, skeletal muscle, bone marrow, cortical bone, and various adipose tissue depots, including visceral (VAT), intraperitoneal (IPAT), retroperitoneal (RPAT), subcutaneous (SAT), deep (DSAT), and superficial SAT (SSAT), as well as intermuscular adipose tissue (IMAT). The models were trained and validated for each target using tenfold cross-validation and test sets.

    RESULTS: The Dice scores on cross validation in SCAPIS were: ResUNET 0.964 (0.909-0.996), UNET++ 0.981 (0.927-0.996), Ghost-UNET 0.961 (0.904-0.991), and Ghost-UNET++ 0.968 (0.910-0.994). All four models showed relatively strong results, however UNET++ had the best performance overall. Ghost-UNET++ performed competitively compared to UNET++ and showed a more computationally efficient approach.

    CONCLUSION: Fully automated segmentation techniques can be successfully applied to a 3-slice CT imaging protocol to analyze multiple tissues and organs related to BC. The overall best performance was achieved by UNET++, against which Ghost-UNET++ showed competitive results based on a more computationally efficient approach. The use of fully automated segmentation methods can reduce analysis time and provide objective results in large-scale studies of BC.

    Place, publisher, year, edition, pages
    BioMed Central (BMC), 2023
    Keywords
    Body composition, Computed tomography, Deep learning, Medical imaging, Segmentation
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:uu:diva-514086 (URN)10.1186/s12859-023-05462-2 (DOI)001068040700003 ()37723444 (PubMedID)
    Available from: 2023-10-13 Created: 2023-10-13 Last updated: 2025-04-27Bibliographically approved
    2. Voxel-wise body composition analysis using image registration of a three-slice CT imaging protocol: methodology and proof-of-concept studies
    Open this publication in new window or tab >>Voxel-wise body composition analysis using image registration of a three-slice CT imaging protocol: methodology and proof-of-concept studies
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    2024 (English)In: Biomedical engineering online, E-ISSN 1475-925X, Vol. 23, no 1, article id 42Article in journal (Refereed) Published
    Abstract [en]

    Background Computed tomography (CT) is an imaging modality commonly used for studies of internal body structures and very useful for detailed studies of body composition. The aim of this study was to develop and evaluate a fully automatic image registration framework for inter-subject CT slice registration. The aim was also to use the results, in a set of proof-of-concept studies, for voxel-wise statistical body composition analysis (Imiomics) of correlations between imaging and non-imaging data.Methods The current study utilized three single-slice CT images of the liver, abdomen, and thigh from two large cohort studies, SCAPIS and IGT. The image registration method developed and evaluated used both CT images together with image-derived tissue and organ segmentation masks. To evaluate the performance of the registration method, a set of baseline 3-single-slice CT images (from 2780 subjects including 8285 slices) from the SCAPIS and IGT cohorts were registered. Vector magnitude and intensity magnitude error indicating inverse consistency were used for evaluation. Image registration results were further used for voxel-wise analysis of associations between the CT images (as represented by tissue volume from Hounsfield unit and Jacobian determinant) and various explicit measurements of various tissues, fat depots, and organs collected in both cohort studies.Results Our findings demonstrated that the key organs and anatomical structures were registered appropriately. The evaluation parameters of inverse consistency, such as vector magnitude and intensity magnitude error, were on average less than 3 mm and 50 Hounsfield units. The registration followed by Imiomics analysis enabled the examination of associations between various explicit measurements (liver, spleen, abdominal muscle, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), thigh SAT, intermuscular adipose tissue (IMAT), and thigh muscle) and the voxel-wise image information.Conclusion The developed and evaluated framework allows accurate image registrations of the collected three single-slice CT images and enables detailed voxel-wise studies of associations between body composition and associated diseases and risk factors.

    Place, publisher, year, edition, pages
    Springer Nature, 2024
    Keywords
    Image registration, Computed tomography, Body composition, Imiomics analysis
    National Category
    Radiology, Nuclear Medicine and Medical Imaging Medical Imaging
    Identifiers
    urn:nbn:se:uu:diva-528252 (URN)10.1186/s12938-024-01235-x (DOI)001201490300001 ()38614974 (PubMedID)
    Available from: 2024-05-21 Created: 2024-05-21 Last updated: 2025-04-27Bibliographically approved
    3. Interpretable Uncertainty-Aware Deep Regression with Cohort Saliency Analysis for Three-Slice CT Imaging Studies
    Open this publication in new window or tab >>Interpretable Uncertainty-Aware Deep Regression with Cohort Saliency Analysis for Three-Slice CT Imaging Studies
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    2024 (English)In: Proceedings of The 7nd International Conference on Medical Imaging with Deep Learning / [ed] Ninon Burgos; Caroline Petitjean; Maria Vakalopoulou; Stergios Christodoulidis; Pierrick Coupe; Hervé Delingette; Carole Lartizien; Diana Mateus, MLResearchPress , 2024, p. 17-32Conference paper, Published paper (Refereed)
    Abstract [en]

    Obesity is associated with an increased risk of morbidity and mortality. Achieving a healthy body composition, which involves maintaining a balance between fat and muscle mass, is important for metabolic health and preventing chronic diseases. Computed tomography (CT) imaging offers detailed insights into the body’s internal structure, aiding in understanding body composition and its related factors. In this feasibility study, we utilized CT image data from 2,724 subjects from the large metabolic health cohort studies SCAPIS and IGT. We train and evaluate an uncertainty-aware deep regression based ResNet-50 network, which outputs its prediction as mean and variance, for quantification of cross-sectional areas of liver, visceral adipose tissue (VAT), and thigh muscle. This was done using collages of three single-slice CT images from the liver, abdomen, and thigh regions. The model demonstrated promising results with the evaluation metrics – including R-squared (R2) and mean absolute error (MAE) for predictions. Additionally, for interpretability, the model was evaluated with saliency analysis based on Grad-CAM (Gradient-weighted Class Activation Mapping) at stages 2, 3, and 4 of the network. Deformable image registration to a template subject further enabled cohort saliency analysis that provide group-wise visualization of image regions of importance for associations to biomarkers of interest. We found that the networks focus on relevant regions for each target, according to prior knowledge.

    Place, publisher, year, edition, pages
    MLResearchPress, 2024
    Series
    Proceedings of Machine Learning Research, PMLR, E-ISSN 2640-3498 ; 250
    National Category
    Radiology and Medical Imaging Epidemiology
    Research subject
    Machine learning
    Identifiers
    urn:nbn:se:uu:diva-554960 (URN)
    Conference
    The 7th International Conference on Medical Imaging with Deep Learning, 3-5 July, 2024, Paris, France
    Funder
    Swedish Research Council, 2019-04756EXODIAB - Excellence of Diabetes Research in SwedenSwedish Heart Lung Foundation
    Available from: 2025-04-18 Created: 2025-04-18 Last updated: 2025-06-10Bibliographically approved
    4. Interpretable Deep Learning-based Prediction Studies of Body Composition, Age, BMI and Sex from a Three Single-Slice CT Imaging Protocol
    Open this publication in new window or tab >>Interpretable Deep Learning-based Prediction Studies of Body Composition, Age, BMI and Sex from a Three Single-Slice CT Imaging Protocol
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences Radiology and Medical Imaging
    Identifiers
    urn:nbn:se:uu:diva-555403 (URN)
    Available from: 2025-04-25 Created: 2025-04-25 Last updated: 2025-04-27
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  • Public defence: 2025-08-29 10:00 Humanistiska teatern, Uppsala
    Ericson, Suzanne
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Languages, Department of English.
    Responsible Reading in the English Classroom: Working with Indigenous Literature in Teacher Education to Promote Environmental Justice2025Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis responds to the challenge of integrating Education for Sustainable Development (ESD) into English education through a focus on teacher training and the pedagogical potential of literary texts. Guided by the work of North American Indigenous writers Driftpile Cree poet Billy-Ray Belcourt, Laguna Pueblo author Leslie Marmon Silko, and Nisga’a poet Jordan Abel, the research develops a methodological framework for teaching tomorrow’s educators to critically engage with literary texts with a focus on environmental justice, reflect on their positionality in relation to these, and collaborate towards transformative action. It argues that these texts have significant didactic value in fostering competencies in sustainability, reading, and teaching among student teachers. The reading practices developed are adaptable for upper-secondary English teaching and align with national and international ESD directives. By emphasising the vital role of humanities subjects in sustainability education and the responsibility inherent in reading and thus, also, teaching reading, this thesis contributes to ongoing efforts to build a more environmentally just world through education.

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  • Public defence: 2025-08-29 10:15 E-22, Visby, Gotland
    Bhati, Harsh Vardhan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Law, Department of Law.
    Powering Preservation: Balancing Heritage Conservation and Energy Transition in World Heritage Cities2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation examines the intersection of heritage conservation and sustainable energy transition in the UNESCO World Heritage sites of Visby (Sweden), Jaipur (India), and Bath (England, United Kingdom). This dissertation, presented through a series of four articles investigates how different national and local legal systems respond to similar international legal obligations and how these legal norms are interpreted and applied in practice by decision-makers and relevant stakeholders at the local level, particularly with regard to balancing cultural heritage conservation with energy transition and sustainability goals.

    The first article examines the national legal systems of Sweden, India, and the United Kingdom and how the obligations of the World Heritage Convention are implemented in light of commitments to mitigate climate change under the Paris Agreement in the World Heritage cities of Visby, Jaipur, and Bath. The second and third articles focus on Visby (Sweden) and Jaipur (India) to investigate how public officials and other relevant stakeholders interpret and apply national and international obligations to preserve cultural heritage in light of commitments to reduce greenhouse gas emissions and energy use. It further explores how these legal frameworks influence perception and decision-making processes, as well as how they produce both opportunities and challenges in balancing energy transition and sustainability with heritage conservation at the local level. The fourth article examines the effectiveness, legitimacy, and fairness of conservation practices under the World Heritage Convention, specifically regarding the rights of Indigenous Peoples and local communities in heritage nomination, protection, and management, and uses biocultural heritage and rights as a framework for integrating natural, cultural, tangible, and intangible heritage, with illustrative examples from Kenya and Sweden.

    This thesis contributes to heritage and energy sustainability by recommending a more flexible approach within existing legal frameworks that incorporates soft-law mechanisms, such as funding and education programs, as well as capacity building among public officials and local communities to bridge policy and practice gaps in World Heritage cities. Drawing inspiration from the emerging idea of biocultural heritage, it additionally highlights the need to protect the relationships between people and their environments, even in cities. These findings underscore the importance of shared global responsibility to conserve World Heritage sites in the face of evolving environmental and urban challenges.

    List of papers
    1. Energy Sustainability in UNESCO World Heritage Cities: On the Local and National Implementation of International Law in Visby (Sweden), Jaipur (India), and Bath (United Kingdom)
    Open this publication in new window or tab >>Energy Sustainability in UNESCO World Heritage Cities: On the Local and National Implementation of International Law in Visby (Sweden), Jaipur (India), and Bath (United Kingdom)
    (English)Manuscript (preprint) (Other academic)
    National Category
    Law
    Research subject
    Environmental Law
    Identifiers
    urn:nbn:se:uu:diva-555976 (URN)
    Available from: 2025-05-07 Created: 2025-05-07 Last updated: 2025-05-08
    2. Implementing the Green Energy Transition in a UNESCO World Heritage City: A Case Study of Visby, Sweden
    Open this publication in new window or tab >>Implementing the Green Energy Transition in a UNESCO World Heritage City: A Case Study of Visby, Sweden
    2025 (English)In: Journal for European Environmental & Planning Law, ISSN 1613-7272, E-ISSN 1876-0104, Vol. 22, no 3, p. 271-324Article in journal (Refereed) Published
    Abstract [en]

    Over 300 cities are inscribed on the World Heritage List. While each site has its unique challenges and opportunities, in each of them a balance must be achieved in protecting heritage values and meeting demands of modern life, including the demand for energy efficiency and the reduction of greenhouse gas emissions. This article uses Visby (Sweden) as a case study to examine how conservation laws implementing the World Heritage Convention in light of international commitments to mitigate climate change can influence the balance between cultural heritage preservation and energy measures in historic sites. International laws must be implemented by states. But these national laws must be applied locally, in each heritage site. It is therefore important to examine how regional and local decision makers, including individual property owners, navigate and understand their obligations stemming from international laws in order to understand the impact and challenges in meeting sustainability goals in heritage sites. We find that while Visby’s World Heritage status promotes a high level of cultural heritage protection, restrictive laws alone fall short in achieving sustainability. Supportive factors such as funding, planning tools, knowledge support and dissemination, and community engagement help bridge these gaps. We recommend further support for financial incentives, place-based technological solutions, and collaboration amongst experts and others to help officials and property owners make choices that are sustainable from both energy and heritage perspectives.

    Place, publisher, year, edition, pages
    Brill Nijhoff, 2025
    Keywords
    World Heritage cities, Green energy transition, Environmental law, Multilateral governance, Local implementation
    National Category
    Law
    Research subject
    Environmental Law
    Identifiers
    urn:nbn:se:uu:diva-555975 (URN)10.1163/18760104-22030004 (DOI)
    Funder
    Swedish Energy AgencyRiksbankens Jubileumsfond
    Available from: 2025-05-07 Created: 2025-05-07 Last updated: 2025-06-16Bibliographically approved
    3. Implementing cultural heritage conservation and energy sustainability in the UNESCO World Heritage site of Jaipur city, India
    Open this publication in new window or tab >>Implementing cultural heritage conservation and energy sustainability in the UNESCO World Heritage site of Jaipur city, India
    2025 (English)In: Frontiers in Sustainable Cities, E-ISSN 2624-9634, Vol. 7, p. 1-24Article in journal (Refereed) Published
    Abstract [en]

    World Heritage cities face the complex challenges of balancing cultural heritage protection with the UN Sustainable Development Goals, particularly reducing greenhouse gas emissions and achieving energy sustainability. However, implementing these commitments at the local level often presents challenges. Using the walled city of Jaipur, a UNESCO World Heritage site in India, as a case study, this article examines the impacts, opportunities, and challenges in implementing and applying international and national obligations to preserve cultural heritage in light of obligations to reduce energy use and greenhouse gas emissions in historic urban areas. This article is based on legal research, as well as 9 semi-structured interviews, which include one group interview with three municipal representatives and individual interviews with one state representative, five heritage professionals and consultants, and two heritage property owners. The results show that World Heritage status has enhanced cultural heritage protection while allowing measures toward energy sustainability. Traditional architectural practices, such as the passive climate design of havelis, are already energy efficient, while interventions, such as the integration of solar panels and adaptive re-use of havelis, demonstrate compatibility between heritage conservation and sustainability goals. However, there continue to be challenges, including limited expertise, capacity, and financial resources, while governance inefficiencies, commercialization pressures, inadequate support for residents, and limited community engagement further hinder progress. The study recommends strengthening the governance framework and enforcement mechanisms, providing targeted financial and technological support, and fostering inclusive collaboration and education among these actors to align heritage conservation with energy sustainability at the local level.

    Keywords
    World Heritage cities, international law, local implementation, heritage governance, heritage conservation, energy sustainability
    National Category
    Law
    Research subject
    Environmental Law; Environmental Law
    Identifiers
    urn:nbn:se:uu:diva-555977 (URN)10.3389/frsc.2025.1548279 (DOI)
    Available from: 2025-05-07 Created: 2025-05-07 Last updated: 2025-06-03Bibliographically approved
    4. Protection of Biocultural Heritage in the Anthropocene: Towards Reconciling Natural, Cultural, Tangible and Intangible Heritage
    Open this publication in new window or tab >>Protection of Biocultural Heritage in the Anthropocene: Towards Reconciling Natural, Cultural, Tangible and Intangible Heritage
    2023 (English)In: Journal of environmental law, ISSN 0952-8873, E-ISSN 1464-374X, Vol. 35, no 3, p. 353-375, article id eqad020Article in journal (Refereed) Published
    Abstract [en]

    This article examines the effectiveness, legitimacy, and fairness of heritage conservation outcomes under the 1972 World Heritage Convention (1972 WHC), with a focus on recognising and respecting the rights of Indigenous Peoples in heritage nomination, protection, and management. Examining conflicts surrounding World Heritage sites in Kenya and Sweden, this article argues that recognition of biocultural heritage and biocultural rights can promote environmental justice and help meet global environmental challenges. To promote the conservation of both built and natural landscapes, the article recommends expanding protection for the relationship between humans and their environment. Recognising biocultural heritage under UNESCO conventions could promote Indigenous sovereignty, protect cultural and natural heritage, and contribute to global efforts to address climate change. The article calls for further research mapping biocultural heritage in natural and mixed heritage sites and advocates for fuller engagement with Indigenous Peoples to increase the ability of the 1972 WHC to promote sustainability as it enters its second half-century.

    Place, publisher, year, edition, pages
    Oxford University Press, 2023
    Keywords
    multilateral environmental agreement, international cultural heritage law, biocultural heritage, World Heritage Convention, UNESCO
    National Category
    Law
    Research subject
    Environmental Law
    Identifiers
    urn:nbn:se:uu:diva-506731 (URN)10.1093/jel/eqad020 (DOI)001021189500001 ()
    Funder
    Uppsala UniversityRiksbankens Jubileumsfond
    Available from: 2023-06-29 Created: 2023-06-29 Last updated: 2025-05-21Bibliographically approved
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  • Public defence: 2025-09-03 09:15 Heinz-Otto Kreiss, Uppsala
    Ullah, Md Imran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Advanced Converter Control Strategies for Wave Energy Systems: Energy Storage System, Power Quality Assessment and Remote Island Electrification2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Net-zero emissions from electricity production and their effect on global warming have led to an increased focus on power production from different renewable energy resources. Wind energy, solar energy, and hydroelectric power currently lead this effort. However, newer technologies, such as wave energy for electricity generation, have significant potential. This thesis investigates the usability and integration of wave energy systems into the electricity grid. This form of energy also has substantial potential in applications such as remote island electrification, which historically has higher carbon emissions due to its reliance on fossil fuels for energy.

    This thesis focuses on Uppsala University’s developed point-absorber-based wave energy converter connected to the grid via power electronics converters. This thesis investigates various grid-side power electronics controls to safely connect the fluctuating frequency and voltage from the wave energy converter to the fixed 50 Hz grid. Additionally, a hybrid energy storage system consisting of a battery and a supercapacitor reduces the effect of variability and increases the reliability. The results illustrate the increased controllability of power flow to the grid and improved power quality. Additionally, the use of supercapacitors also increased the battery's performance.

    The other part of the thesis explores the use of wave energy for remote island electrification. A novel multimode converter control (grid-feeding, grid-support, isolated grid-forming) approach is modelled in MATLAB/Simulink in a grid-connected system. These control modes are switched based on the requirement and scenario of the island load. The result shows the seamless transition between different modes, restoration of the island’s load voltage, and the constant power supply in the case of a blackout at acceptable power quality. An experimental study using a wave energy system for island electrification in an isolated grid-forming mode is also performed. The result illustrates the formation of the required load voltage at 50 Hz frequency, along with the functionality of black-start. A novel experimental approach of using a SiC-based converter in a wave energy system for improved power quality is also performed. The load voltage and current harmonics are reduced in all the experimented switching frequencies and comply with the grid code requirements.

    List of papers
    1. A Review of AC and DC Collection Grids for Offshore Renewable Energy with a Qualitative Evaluation for Marine Energy Resources
    Open this publication in new window or tab >>A Review of AC and DC Collection Grids for Offshore Renewable Energy with a Qualitative Evaluation for Marine Energy Resources
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    2022 (English)In: Energies, E-ISSN 1996-1073, Vol. 15, no 16, article id 5816Article in journal (Refereed) Published
    Abstract [en]

    Marine energy resources could be crucial in meeting the increased demand for clean electricity. To enable the use of marine energy resources, developing efficient and durable offshore electrical systems is vital. Currently, there are no large-scale commercial projects with marine energy resources, and the question of how to design such electrical systems is still not settled. A natural starting point in investigating this is to draw on experiences and research from offshore wind power. This article reviews different collection grid topologies and key components for AC and DC grid structures. The review covers aspects such as the type of components, operation and estimated costs of commercially available components. A DC collection grid can be especially suitable for offshore marine energy resources, since the transmission losses are expected to be lower, and the electrical components could possibly be made smaller. Therefore, five DC collection grid topologies are proposed and qualitatively evaluated for marine energy resources using submerged and non-submerged marine energy converters. The properties, advantages and disadvantages of the proposed topologies are discussed, and it is concluded that a suitable electrical system for a marine energy farm will most surely be based on a site-specific techno-economic analysis.

    Place, publisher, year, edition, pages
    MDPI, 2022
    Keywords
    AC and DC collection grids, offshore renewable energy, electrical systems
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-481506 (URN)10.3390/en15165816 (DOI)000845978400001 ()
    Funder
    Uppsala UniversityStandUpEuropean Regional Development Fund (ERDF)Swedish Energy Agency, 48347-1EU, Horizon 2020, 101036457
    Available from: 2022-08-11 Created: 2022-08-11 Last updated: 2025-05-13Bibliographically approved
    2. Analysis of a hybrid energy storage system in a grid-tied wave energy converter for varying power demand
    Open this publication in new window or tab >>Analysis of a hybrid energy storage system in a grid-tied wave energy converter for varying power demand
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    2022 (English)In: 11th International Conference on Renewable Power Generation - Meeting net zero carbon (RPG 2022), Institution of Engineering and Technology, 2022, p. 1-5Conference paper, Published paper (Refereed)
    Abstract [en]

    Wave energy is one of the emerging sustainable energy resources due to its high energy density and vast untapped areas. Nevertheless, the intermittency of wave resources is a significant challenge for the grid operator. Additionally, a varying grid demand is an added complexity to wave resources. Energy storage systems such as batteries and supercapacitors can be used to smoothen the power injection into the grid and match the available energy with the grid demand. Thus, this study compares battery energy storage with the hybrid energy storage system and proposes a control strategy to reduce the power fluctuations on the battery, allowing power delivery for varying grid demands. The study found that the hybrid system increases the system efficiency, in addition to the reduction in power fluctuations and enhancement of battery's performance, among other gains when the proposed control is implemented.

    Place, publisher, year, edition, pages
    Institution of Engineering and Technology, 2022
    Keywords
    battery storage plants, distributed power generation, energy storage, power generation control, power grids, supercapacitors, sustainable development, wave power generation, smart power grids
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-492957 (URN)10.1049/icp.2022.1828 (DOI)978-1-83953-789-9 (ISBN)
    Conference
    11th International Conference on Renewable Power Generation - Meeting net zero carbon (RPG 2022), 22-23 September, 2022, Online & London, UK
    Funder
    StandUpSwedish Energy Agency, 48347-1Interreg North Sea Region, Programme 2015–2020Uppsala UniversityEuropean Regional Development Fund (ERDF)Swedish Energy Agency, 48346-1
    Available from: 2023-01-11 Created: 2023-01-11 Last updated: 2025-05-13Bibliographically approved
    3. Power quality assessment of a wave energy converter using energy storage
    Open this publication in new window or tab >>Power quality assessment of a wave energy converter using energy storage
    2023 (English)In: Proceedings of the 15th European Wave and Tidal Energy Conference, Bilbao, 3-7 September 2023, European Wave and Tidal Energy Conference , 2023, article id 315Conference paper, Published paper (Refereed)
    Abstract [en]

    Wave energy has been an immense area of interest in research and industry in our move towards a sustainable energy production society due to its high energy density and surface area. However, the grid connection of wave energy converters is still one of the major challenges due to the complexity of varying wave resources (amplitude and frequency). Wave energy converter grid integration can lead to several potential challenges, such as voltage fluctuations, harmonics and flicker. Using an energy storage system can help mitigate a few challenges by balancing the grid demand with the wave energy converter power supply. Hence improving the power quality. This study assesses the power quality of wave energy converters equipped with energy storage against the scenario without any energy storage at different power levels. The power quality in this paper is investigated using total harmonic distortion (THD)of the grid current, dc-link voltage ripple and battery current ripple. The study shows that the addition of a hybrid energy storage system lowers the grid current THDat the point of common coupling (PCC), stabilizes the dc-link voltage ripple and reduces the stress of the battery.

    Place, publisher, year, edition, pages
    European Wave and Tidal Energy Conference, 2023
    Series
    Proceedings of the European Wave and Tidal Energy Conference (EWTEC), ISSN 2706-6932, E-ISSN 2706-6940 ; 15
    Keywords
    Wave energy, Grid connection, simscape, power electronics, electrical modelling, control, direct drive machine, linear generator
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-512535 (URN)10.36688/ewtec-2023-315 (DOI)
    Conference
    15th European Wave and Tidal Energy Conference, Bilbao, Spain, 3-7 September, 2023
    Funder
    Uppsala UniversityStandUpÅForsk (Ångpanneföreningen's Foundation for Research and Development)
    Available from: 2023-09-26 Created: 2023-09-26 Last updated: 2025-05-13Bibliographically approved
    4. Grid-forming control for the linear-generator-based wave energy converter for the electrification of remote islands
    Open this publication in new window or tab >>Grid-forming control for the linear-generator-based wave energy converter for the electrification of remote islands
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    2023 (English)Conference paper, Published paper (Refereed)
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-513380 (URN)
    Conference
    International Conference on Power Electronics, Machines and Drives
    Available from: 2023-10-05 Created: 2023-10-05 Last updated: 2025-05-13
    5. Multi-mode converter control for linear generator-based wave energy system
    Open this publication in new window or tab >>Multi-mode converter control for linear generator-based wave energy system
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    2024 (English)In: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    The electrification of remote islands has long been a subject of research interest, primarily because of their historical reliance on fossil fuels, leading to a significant carbon footprint. Recent advancements in wave energy converters offer a promising avenue to make these islands more self-sustainable while considerably reducing carbon emissions. However, the persistent issue of voltage dips due to weaker grids continues to pose a challenge. This study introduces a multi-mode converter control strategy with the goal of electrifying remote islands, employing a linear generator-based wave energy converter in a unified electrical model. Various scenarios, including voltage dips and mainland grid disconnection, are simulated using MATLAB/Simulink. The study demonstrates the converter's ability to transition swiftly and smoothly in response to these scenarios, ensuring an uninterrupted power supply. Furthermore, the analysis indicates that the power quality at the point of common coupling remains well within acceptable standards.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2024
    Keywords
    energy storage, microgrids, power electronics, power system control, wave power generation
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-513385 (URN)10.1049/rpg2.12995 (DOI)001207249900001 ()
    Available from: 2023-10-05 Created: 2023-10-05 Last updated: 2025-05-13
    6. Isolated Grid-Forming Control of Wave Energy Converter for Island Electrification
    Open this publication in new window or tab >>Isolated Grid-Forming Control of Wave Energy Converter for Island Electrification
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    2025 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 13, p. 50860-50875Article in journal (Refereed) Published
    Abstract [en]

    As the world transitions to renewable electrification to reduce CO2 emissions, remote island electrification remains a challenge. Although some islands are connected to the grid, many still rely on fossil fuels for electricity generation. Several studies indicate that renewable energy sources, such as wave energy, have the potential to make these islands self-reliant because of their substantial power potential. However, research on the control of power electronics converters for these systems remains limited. This paper proposes isolated grid-forming control for island electrification to address this gap using a wave energy converter and an energy storage system. Resistive loading control is implemented to optimize the power absorption of the generator. The result illustrates the establishment of the required AC voltage and 50 Hz frequency in the island load, ensuring harmonics compliance with the recommended standards. Experiments were conducted to test and validate the operation of different converter controls. The results also demonstrate the converter's ability to black-start the island load and automatically transition the load current with varying loads in a few milliseconds. Furthermore, the power quality produced by the wave energy converter presents one of its significant challenges. Therefore, the performance of two distinct converter technologies was compared. The performance of the IGBT converter was evaluated against that of the SiC-based converter in terms of power quality. The study demonstrates that the use of SiC enhances power quality in all switching frequencies tested, achieving the most significant reduction of 78% in current THD and 92% in voltage THD at the 25 kHz switching frequency, thus validating its advantages for wave energy converter applications.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2025
    Keywords
    Wave energy conversion, Renewable energy sources, Harmonic analysis, Energy storage, Electrification, Costs, Power quality, Electricity, Electric potential, Control systems, Wave energy, control system, island electrification, grid-forming, energy storage system control, harmonics mitigation
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering Energy Systems Energy Engineering
    Identifiers
    urn:nbn:se:uu:diva-554668 (URN)10.1109/ACCESS.2025.3552820 (DOI)001453644600002 ()2-s2.0-105001555406 (Scopus ID)
    Funder
    StandUp
    Available from: 2025-04-16 Created: 2025-04-16 Last updated: 2025-05-13Bibliographically approved
    7. Bringing Wave Energy to the Electricity Market: Control Perspective and the Need for Energy Storage Systems
    Open this publication in new window or tab >>Bringing Wave Energy to the Electricity Market: Control Perspective and the Need for Energy Storage Systems
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-556253 (URN)
    Available from: 2025-05-12 Created: 2025-05-12 Last updated: 2025-05-13
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  • Public defence: 2025-09-03 10:00 Rudbecksalen, Uppsala
    Li, Weihan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Studies on the Brain Vasculature: Blood-Brain Barrier Permeability and Brain Inflammation2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The blood-brain barrier (BBB) is a specialized vascular interface that protects the central nervous system (CNS) by tightly regulating molecular exchange between the blood and brain parenchyma. Despite its importance, the mechanisms underlying BBB development, maintenance, and dysfunction remain incompletely understood. In this thesis, we investigated the effects of Angiopoietin 2 (ANGPT2) deficiency during development and Claudin 5 (CLDN5) loss in adulthood on BBB integrity, developed a refined method for isolating brain vascular cells, and performed cross-species transcriptomic comparisons to identify gene expression similarities and differences between mouse and human brain pericytes.

    Our results show that constitutive Angpt2 knockout leads to spatially localized vascular malformations in the adult brain, particularly in the basal ganglia and somatosensory cortex, accompanied by increased permeability, angiogenesis, mural cell alterations, ECM accumulation, and glial reactivity. Single-cell RNA sequencing identified a distinct endothelial population in Angpt2 knockout mice enriched for genes involved in angiogenesis and matrix remodeling. In contrast, inducible, endothelial-specific deletion of Cldn5 in adult mice caused size-selective BBB leakage, neuroinflammation, and widespread transcriptional changes in both CLDN5-positive and -negative endothelial cells, indicating indirect effects. Additionally, to facilitate high-quality single-cell analysis, we developed a magnetic bead-based protocol for isolating brain microvascular fragments, which enriched for vascular and perivascular cell types while preserving mRNA and protein integrity. Finally, we compared gene expression profiles of mouse and human brain pericytes using public datasets, revealing species-specific transcriptional differences.

    Together, these studies provide new insights into the molecular regulation of the BBB in both developmental and mature contexts. By integrating genetic models, imaging, single-cell technologies, and cross-species analysis, our work advances understanding of neurovascular biology and offers valuable tools and knowledge to enhance the translational relevance of preclinical models in neurological research.

    List of papers
    1. Angiopoietin 2 deficiency results in formation of region-specific brain vascular malformations
    Open this publication in new window or tab >>Angiopoietin 2 deficiency results in formation of region-specific brain vascular malformations
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-556468 (URN)
    Available from: 2025-05-13 Created: 2025-05-13 Last updated: 2025-05-13
    2. Different gene expression patterns between mouse and human brain pericytes revealed by single-cell/nucleus RNA sequencing
    Open this publication in new window or tab >>Different gene expression patterns between mouse and human brain pericytes revealed by single-cell/nucleus RNA sequencing
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    2024 (English)In: Vascular pharmacology, ISSN 1537-1891, E-ISSN 1879-3649, Vol. 157, article id 107434Article in journal (Refereed) Published
    Abstract [en]

    Aims: Pericytes in the brain play important roles for microvascular physiology and pathology and are affected in neurological disorders and neurodegenerative diseases. Mouse models are often utilized for pathophysiology studies of the role of pericytes in disease; however, the translatability is unclear as brain pericytes from mouse and human have not been systematically compared. In this study, we investigate the similarities and differences of brain pericyte gene expression between mouse and human. Our analysis provides a comprehensive resource for translational studies of brain pericytes.

    Methods: We integrated and compared four mouse and human adult brain pericyte single-cell/nucleus RNAsequencing datasets derived using two single-cell RNA sequencing platforms: Smart-seq and 10x. Gene expression abundance and specificity were analyzed. Pericyte-specific/enriched genes were assigned by comparison with endothelial cells present in the same datasets, and mouse and human pericyte transcriptomes were subsequently compared to identify species-specific genes.

    Results: An overall concordance between pericyte transcriptomes was found in both Smart-seq and 10x data. 206 orthologous genes were consistently differentially expressed between human and mouse from both platforms, 91 genes were specific/up-regulated in human and 115 in mouse. Gene ontology analysis revealed differences in transporter categories in mouse and human brain pericytes. Importantly, several genes implicated in human disease were expressed in human but not in mouse brain pericytes, including SLC6A1, CACNA2D3, and SLC20A2.

    Conclusions: This study provides a systematic illustration of the similarities and differences between mouse and human adult brain pericytes.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    Keywords
    Pericyte, Brain vasculature, Single-cell RNA-sequencing, Species difference
    National Category
    Neurosciences Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-542267 (URN)10.1016/j.vph.2024.107434 (DOI)001342481800001 ()39423955 (PubMedID)
    Funder
    Swedish Research Council, 2023-02655Swedish Research Council, 2022-06725
    Available from: 2024-11-13 Created: 2024-11-13 Last updated: 2025-05-13Bibliographically approved
    3. Mosaic deletion of claudin-5 reveals rapid non-cell-autonomous consequences of blood-brain barrier leakage
    Open this publication in new window or tab >>Mosaic deletion of claudin-5 reveals rapid non-cell-autonomous consequences of blood-brain barrier leakage
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    2024 (English)In: Cell Reports, E-ISSN 2211-1247, Vol. 43, no 3, article id 113911Article in journal (Refereed) Published
    Abstract [en]

    Claudin-5 (CLDN5) is an endothelial tight junction protein essential for blood-brain barrier (BBB) formation. Abnormal CLDN5 expression is common in brain disease, and knockdown of Cldn5 at the BBB has been proposed to facilitate drug delivery to the brain. To study the consequences of CLDN5 loss in the mature brain, we induced mosaic endothelial-specific Cldn5 gene ablation in adult mice (Cldn5iECKO). These mice displayed increased BBB permeability to tracers up to 10 kDa in size from 6 days post induction (dpi) and ensuing lethality from 10 dpi. Single-cell RNA sequencing at 11 dpi revealed profound transcriptomic differences in brain endothelial cells regardless of their Cldn5 status in mosaic mice, suggesting major non-cell-autonomous responses. Reactive microglia and astrocytes suggested rapid cellular responses to BBB leakage. Our study demonstrates a critical role for CLDN5 in the adult BBB and provides molecular insight into the consequences and risks associated with CLDN5 inhibition.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-527246 (URN)10.1016/j.celrep.2024.113911 (DOI)001204344300001 ()38446668 (PubMedID)
    Funder
    Swedish Research Council, 2023-02655Swedish Research Council, 2015-00550Swedish Research Council, 2021-04896EU, European Research Council, AdG294556Swedish Cancer Society, 150735Knut and Alice Wallenberg Foundation, 2015.0030Knut and Alice Wallenberg Foundation, 2020.0057EU, European Research Council, 864522European Regional Development Fund (ERDF)
    Available from: 2024-04-26 Created: 2024-04-26 Last updated: 2025-05-13Bibliographically approved
    4. A robust and efficient microvascular isolation method for multimodal characterization of the mouse brain vasculature
    Open this publication in new window or tab >>A robust and efficient microvascular isolation method for multimodal characterization of the mouse brain vasculature
    Show others...
    2023 (English)In: CELL REPORTS METHODS, ISSN 2667-2375, Vol. 3, no 3, article id 100431Article in journal (Refereed) Published
    Abstract [en]

    Studying disease-related changes in the brain vasculature is warranted due to its crucial role in supplying oxygen and nutrients and removing waste and due to the anticipated vascular dysfunction in brain dis-eases. To this end, we have developed a protocol for fast and simple isolation of brain vascular fragments without the use of transgenic reporters. We used it to isolate and analyze 22,515 cells by single-cell RNA sequencing. The cells distributed into 23 distinct clusters corresponding to all known vascular and perivas-cular cell types in the brain. Western blot analysis also suggested that the protocol is suitable for proteomic analysis. We further adapted it for the establishment of primary cell cultures. The protocol generated highly reproducible results. In conclusion, we have developed a simple and robust brain vascular isolation proto-col suitable for different experimental modalities, such as single-cell analyses, western blotting, and pri-mary cell culture.

    Place, publisher, year, edition, pages
    ElsevierELSEVIER, 2023
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:uu:diva-502120 (URN)10.1016/j.crmeth.2023.100431 (DOI)000969872600001 ()37056377 (PubMedID)
    Funder
    Karolinska InstituteSwedish Research Council, 2019:00285
    Available from: 2023-05-23 Created: 2023-05-23 Last updated: 2025-05-13Bibliographically approved
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  • Public defence: 2025-09-04 09:00 H:son Holmdahlsalen, Uppsala
    Tarai, Sambit
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Deep Learning-Based Large-Scale Medical Image Analysis: From Segmentation to Survival Analysis of Oncologic FDG-PET/CT2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis explores advanced deep learning methodologies for the analysis of multi-modal medical images, specifically focusing on whole-body oncologic [18F]fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) data. The overall goal is to develop automated tools to enhance tumor detection, segmentation, and prediction of clinical outcomes, thereby contributing to improved patient prognostics and personalized treatment planning.

    The research includes several key areas in the field of deep learning based medical image analysis. In paper I and II, a novel end-to-end framework is proposed for automated tumor segmentation in whole-body 3D scans, utilizing a tumor-aware segmentation prior derived from multi-directional 2D projections of PET/CT or PET/magnetic resonance imaging (PET/MRI) data. This method improved overall segmentation accuracy, especially for small and challenging tumors often missed by conventional approaches. In paper III, an end-to-end interpretable framework for predicting total metabolic tumor volume (TMTV) from tissue-wise FDG-PET/CT projections is introduced. The framework included an image registration-based cohort saliency analysis for enhanced interpretability. This approach demonstrates improved TMTV prediction compared to baseline methods and highlights the tumor regions contributing to the predictions. In Paper IV, we developed a time-driven survival analysis approach for non-small cell lung cancer patients by incorporating: (1) tumor segmentation results from Paper I, (2) tissue-wise projections from Paper II, and (3) the deep regression framework from Paper III. The resulting framework predicts overall survival (OS) probabilities as a function of time, outperforming baseline methods and utilizing saliency analysis to identify influential image regions. 

    Collectively, this work presents significant advancements in the development and application of deep learning methodologies for medical image analysis, with future potential for integration into clinical workflows. These methods could support personalized treatment planning and improve patient outcomes. Moreover, the developed tools open new opportunities for data-driven research, enabling large-scale investigation into the relationships between imaging biomarkers and clinical outcome across diverse patient cohorts.

    List of papers
    1. Improved automated tumor segmentation in whole-body 3D scans using multi-directional 2D projection-based priors
    Open this publication in new window or tab >>Improved automated tumor segmentation in whole-body 3D scans using multi-directional 2D projection-based priors
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    2024 (English)In: Heliyon, E-ISSN 2405-8440, Vol. 10, no 4, article id e26414Article in journal (Refereed) Published
    Abstract [en]

    Early cancer detection, guided by whole-body imaging, is important for the overall survival and well-being of the patients. While various computer-assisted systems have been developed to expedite and enhance cancer diagnostics and longitudinal monitoring, the detection and segmentation of tumors, especially from whole-body scans, remain challenging. To address this, we propose a novel end -to-end automated framework that first generates a tumor probability distribution map (TPDM), incorporating prior information about the tumor characteristics (e.g. size, shape, location). Subsequently, the TPDM is integrated with a state-of-the-art 3D segmentation network along with the original PET/CT or PET/MR images. This aims to produce more meaningful tumor segmentation masks compared to using the baseline 3D segmentation network alone. The proposed method was evaluated on three independent cohorts (autoPET, CAR-T, cHL) of images containing different cancer forms, obtained with different imaging modalities, and acquisition parameters and lesions annotated by different experts. The evaluation demonstrated the superiority of our proposed method over the baseline model by significant margins in terms of Dice coefficient, and lesion-wise sensitivity and precision. Many of the extremely small tumor lesions (i.e. the most difficult to segment) were missed by the baseline model but detected by the proposed model without additional false positives, resulting in clinically more relevant assessments. On average, an improvement of 0.0251 (autoPET), 0.144 (CAR-T), and 0.0528 (cHL) in overall Dice was observed. In conclusion, the proposed TPDM-based approach can be integrated with any state-of-the-art 3D UNET with potentially more accurate and robust segmentation results.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    Keywords
    Whole-body tumor segmentation, Medical image analysis, Deep learning, Maximum intensity projection, Backprojection, Segmentation prior
    National Category
    Radiology, Nuclear Medicine and Medical Imaging Medical Imaging Cancer and Oncology
    Identifiers
    urn:nbn:se:uu:diva-526888 (URN)10.1016/j.heliyon.2024.e26414 (DOI)001200166200001 ()38390107 (PubMedID)
    Funder
    Swedish Cancer Society, 201,303 PjF 01Insamlingsstiftelsen Lions Cancerforskningsfond Mellansverige Uppsala-ÖrebroStiftelsen för Makarna Gottfrid och Karin Erikssons fond
    Available from: 2024-04-22 Created: 2024-04-22 Last updated: 2025-05-13Bibliographically approved
    2. Whole-body tumor segmentation from FDG-PET/CT: Leveraging a segmentation prior from tissue-wise projections.
    Open this publication in new window or tab >>Whole-body tumor segmentation from FDG-PET/CT: Leveraging a segmentation prior from tissue-wise projections.
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    2025 (English)In: Heliyon, ISSN 2405-8440, Vol. 11, no 1, p. e41038-, article id e41038Article in journal (Refereed) Published
    Abstract [en]

    ), respectively; *, p-value < 0.05; ns, non-significance. Conclusion: The increased segmentation accuracy could be attributed to the segmentation prior generated from tissue-wise SUV projections, revealing information from various tissues that was useful for segmentation of tumors. The results from this study highlight the potential of the proposed method as a valuable future tool for time-efficient quantification of tumor burden in oncologic FDG-PET/CT.

    Keywords
    Backprojection, Multi-channel multi-angled PET/CT projections, Segmentation prior, Whole-body tumor segmentation
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-548170 (URN)10.1016/j.heliyon.2024.e41038 (DOI)39801978 (PubMedID)
    Available from: 2025-01-22 Created: 2025-01-22 Last updated: 2025-05-13
    3. Prediction of Total Metabolic Tumor Volume from Tissue-Wise FDG-PET/CT Projections, Interpreted Using Cohort Saliency Analysis
    Open this publication in new window or tab >>Prediction of Total Metabolic Tumor Volume from Tissue-Wise FDG-PET/CT Projections, Interpreted Using Cohort Saliency Analysis
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    2024 (English)In: Medical Image Understanding and Analysis: 28th Annual Conference, MIUA 2024, Manchester, UK, July 24–26, 2024, Proceedings, Part II / [ed] Moi Hoon Yap; Connah Kendrick; Ardhendu Behera; Timothy Cootes; Reyer Zwiggelaar, Cham: Springer, 2024, p. 242-255Conference paper, Published paper (Refereed)
    Abstract [en]

    Early and accurate prediction of clinical outcomes holds great potential for patient prognostics and personalized treatment planning. Development of automated methods for estimation of medical image-based clinical parameters (e.g. total metabolic tumor volume, TMTV) could pave the way for predicting advanced clinical outcomes not explicitly available in the images, such as overall survival. We developed an automated framework that extracted tissue-wise multi-channel 2D projections from whole-body FDG-PET/CT volumes, by separating tissues based on CT Hounsfield units, and used a DenseNet-121 to estimate the TMTV from the projections. For transparency and interpretability, an image registration-based cohort saliency analysis was proposed. The network was applied on the autoPET cohort (501 scans representing lymphoma, lung cancer, melanoma) and evaluated using a single channel method (baseline) and a multi-channel method (proposed), for the purpose of comparison. The incorporation of multiple channels demonstrated an advantage in the TMTV prediction, outperforming the baseline model with a ΔMAE = –14.34 ml; ΔR2 = 0.1584; ΔICC = 0.1316 (p-value = 0.0098). The Pearson correlation coefficient (r) was computed between the ground truth (GT) tumor projections and the aggregated saliency maps. Statistical comparison, via bootstrapping, showed that the proposed model consistently outperformed the baseline, with significantly higher r across all cancer types and both sexes, except for melanoma in females. This implied that the aggregated saliency maps generated by the proposed model showed higher correspondence with the GT, compared to the baseline model. Our approach offers a promising and interpretable framework for the automated prediction of TMTV, with further potential to also predict advanced clinical outcomes.

    Place, publisher, year, edition, pages
    Cham: Springer, 2024
    Series
    Lecture Notes in Computer Science (LNCS), ISSN 0302-9743, E-ISSN 1611-3349 ; 14860
    Keywords
    Whole-body PET/CT projections, Deep regression, Cohort saliency analysis
    National Category
    Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:uu:diva-541110 (URN)10.1007/978-3-031-66958-3_18 (DOI)001314340700018 ()978-3-031-66957-6 (ISBN)978-3-031-66958-3 (ISBN)
    Conference
    28th Annual Conference, MIUA 2024, Manchester, UK, July 24–26, 2024
    Funder
    Swedish Cancer Society, 201303 PjF 01Stiftelsen för Makarna Gottfrid och Karin Erikssons fond
    Available from: 2024-10-28 Created: 2024-10-28 Last updated: 2025-05-13Bibliographically approved
    4. Time-driven Survival Analysis from FDG-PET/CT in Non-Small Cell Lung Cancer
    Open this publication in new window or tab >>Time-driven Survival Analysis from FDG-PET/CT in Non-Small Cell Lung Cancer
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    Survival analysis, Lung cancer, Deep regression, Saliency analysis.
    National Category
    Cancer and Oncology
    Identifiers
    urn:nbn:se:uu:diva-556370 (URN)
    Available from: 2025-05-12 Created: 2025-05-12 Last updated: 2025-05-13
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  • Public defence: 2025-09-04 10:15 Lecture Hall 2, Uppsala
    Gülümser, Dogan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Economics.
    Wage Setting and the Gender Wage Gap: Essays on Inequality in Imperfect Labor Markets2025Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Essay I: This paper examines how firms' uncertainty about match productivity in newly created roles affects hiring decisions, entry wages, and workers' labor market outcomes. Using Swedish matched employer-employee data, I analyze 1.7 million new matches and show that firms raise hiring standards by selecting more experienced workers and poaching workers from other firms for the new roles. Workers taking on new roles earn 3% higher entry wages conditional on time-varying and time-invariant worker and firm characteristics. Tenure in new roles is longer on average, leading to an eight percent earnings premium within a given employment relationship. Event study estimates support a causal interpretation of the new job wage premium. This paper sheds light on a previously undocumented source of employer hiring uncertainty - firms' previous experience in hiring for a particular occupation - which contributes to the wage dispersion among similar workers.  

    Essay II (with Marco Palladino, Antoine Bertheau, Alexander Hijzen, Astrid Kunze, Cesar Barreto, Marta Lachowska, Anne Sophie Lassen, Salvatore Lattanzio, Benjamin Lochner, Stefano Lombardi, Jordy Meekes, Balazs Murakozy, and Oskar Nordström Skans): We document the contribution of firm-specific wage premiums to the gender wage gap using a harmonized research design applied to eleven matched employer-employee datasets (ten European countries and in Washington State, USA).These premiums can contribute to cross-country variation in gender wage inequality if (i) they account for a substantial share of the wage dispersion, and (ii) women are less likely to work at high-paying firms (sorting) or receive lower premiums than men within the same firm (pay-setting). Our key finding is that accounting for firm-specific pay premiums provides significant insight into cross-country variation in the gender wage gap. These premiums explain between 5 and 20 percent of total wage inequality for both men and women. Combined, the sorting and pay-setting channels account for 10 to 40 percent of the observed gender wage gap across countries.Despite variation across contexts, several robust patterns emerge. Women’s wages are less responsive than men’s to variations in firm productivity. The sorting of women in low-wage firms are particularly pronounced among older workers and are partly driven by women’s higher representation in firms with greater shares of part-time employment, which tend to offer lower premiums.

    Essay III (with Peter Fredriksson, and Lena Hensvik): We show that men and women respond differently to improvements in outside options, and that these differential responses contribute to the gender pay gap. We develop a simple model of on-the-job search that integrates two crucial gender differences: job preferences and the propensity to renegotiate wages in response to external offers. Both factors contribute to lower wage responsiveness for women when they receive outside offers, and a negative female-male pay gap. However, women's job mobility responses vary depending on the underlying mechanism. To empirically test our model's predictions, we analyze the wage and job mobility responses of men and women to external job opportunities, mediated through family networks. Using Swedish register data, we find that improved outside options are associated with higher within-job wage growth for men but not for women. Importantly, we can rule out that these gendered responses arise from differences in the quality of external offers as these are balanced across genders by design. Additionally, men's and women's job mobility responses are very similar. In light of the model, these findings can only be explained by differences in negotiation behavior between men and women. Policies encouraging women to bargain in response to outside options can thus be a powerful tool for reducing the remaining within-job gender gap in pay.

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  • Public defence: 2025-09-05 09:00 H:son-Holmdahlsalen, Ingång 100, 2 tr., Uppsala
    Dyhrfort, Philip
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Proteomic Profiling of Inflammation Following Traumatic Brain Injury and Cerebral Insults: Decoding Molecular Signatures for Therapeutic Insights2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Traumatic brain injury (TBI) is a complex and diverse condition influenced by various factors, all of which contribute to a wide range of outcomes for the patients. The initial injury renders the brain susceptible to secondary molecular and pathophysiological events, with neuroinflammation considered a crucial secondary mechanism. In this thesis, we investigated the inflammatory response following TBI and drew comparisons with central nervous system (CNS) inflammatory disorders. The aim was to identify distinct inflammatory responses specific to TBI pathology, ultimately contributing to precision medicine and advancing the development of individualized therapies.

    We used cerebral microdialysis (CMD) and proximity extension assay (PEA) to analyze protein expressions in patients with acute severe TBI. Additionally, we conducted mass-spectrometry (MS) analysis on cerebrospinal fluid (CSF) collected from patients with TBI and individuals with various types of encephalitis.

    Paper I - The PEA technique revealed the presence of inflammatory proteins in the brain interstitium during the initial days following severe TBI. Diverse temporal patterns were observed, with some proteins peaking early, others showing middle or late peaks, and some exhibiting biphasic or steady patterns. Notably, while these temporal patterns varied among proteins, unique and consistent patterns were discerned for the same proteins across different patients. Paper II - 21 proteins were selected for a customized panel to explore their temporal dynamics in patients suffering from acute TBI. This structured approach brought the method closer to clinical application and identified proteins of interest for monitoring in this patient group. Paper III - Patients had their CSF analyzed with the use of MS. The resulting protein findings from patients with acute severe TBI were then compared to findings from patients with non-infectious inflammatory CNS disorders, infectious inflammatory CNS disorders and controls. We found distinct proteomic profiles in the CSF of TBI patients compared with the healthy controls and different disease controls, indicating a specific interplay between inflammatory factors, metabolic response, and cell integrity. In relation to primarily infectious or inflammatory disorders, unique inflammatory pathways seem to be engaged and could potentially serve as future treatment targets. Paper IV - CSF from patients with acute severe TBI and COVID-19 patients with neurological symptoms were analysed using MS. Neurofilament light chain (NFL) levels were measured separately. Distinct inflammatory profiles in severe TBI and COVID-19 patients were identified. Elevated NFL levels in both groups indicated white matter injury. The discovery of novel biomarkers specific to each pathology, provide valuable insights into the inflammatory mechanisms and may serve as targets for therapeutic interventions. 

    A more comprehensive understanding of the unique inflammatory response within the CNS following TBI could potentially reveal valuable therapeutic targets. By mapping specific molecular pathways, researchers can develop precise interventions and more effective treatments, tailored to the distinct challenges posed by different conditions.

    List of papers
    1. Monitoring of Protein Biomarkers of Inflammation in Human Traumatic Brain Injury Using Microdialysis and Proximity Extension Assay Technology in Neurointensive Care
    Open this publication in new window or tab >>Monitoring of Protein Biomarkers of Inflammation in Human Traumatic Brain Injury Using Microdialysis and Proximity Extension Assay Technology in Neurointensive Care
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    2019 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 36, no 20, p. 2872-2885Article in journal (Refereed) Published
    Abstract [en]

    Traumatic brain injury (TBI) is followed by secondary injury mechanisms strongly involving neuroinflammation. To monitor the complex inflammatory cascade in human TBI, we used cerebral microdialysis (MD) and multiplex proximity extension assay (PEA) technology and simultaneously measured levels of 92 protein biomarkers of inflammation in MD samples every three hours for five days in 10 patients with severe TBI under neurointensive care. One mu L MD samples were incubated with paired oligonucleotide-conjugated antibodies binding to each protein, allowing quantification by real-time quantitative polymerase chain reaction. Sixty-nine proteins were suitable for statistical analysis. We found five different patterns with either early (<48 h; e.g., CCL20, IL6, LIF, CCL3), mid (48-96 h; e.g., CCL19, CXCL5, CXCL10, MMP1), late (>96 h; e.g., CD40, MCP2, MCP3), biphasic peaks (e.g., CXCL1, CXCL5, IL8) or stable (e.g., CCL4, DNER, VEGFA)/low trends. High protein levels were observed for e.g., CXCL1, CXCL10, MCP1, MCP2, IL8, while e.g., CCL28 and MCP4 were detected at low levels. Several proteins (CCL8, -19, -20, -23, CXCL1, -5, -6, -9, -11, CST5, DNER, Flt3L, and SIRT2) have not been studied previously in human TBI. Cross-correlation analysis revealed that LIF and CXCL5 may play a central role in the inflammatory cascade. This study provides a unique data set with individual temporal trends for potential inflammatory biomarkers in patients with TBI. We conclude that the combination of MD and PEA is a powerful tool to map the complex inflammatory cascade in the injured human brain. The technique offers new possibilities of protein profiling of complex secondary injury pathways.

    Place, publisher, year, edition, pages
    MARY ANN LIEBERT, INC, 2019
    Keywords
    biomarkers, inflammation, microdialysis, molecular tools, neurointensive care, proteomics, traumatic brain injury
    National Category
    Neurology
    Identifiers
    urn:nbn:se:uu:diva-396069 (URN)10.1089/neu.2018.6320 (DOI)000472621900001 ()31017044 (PubMedID)
    Funder
    Swedish Research CouncilVinnova
    Available from: 2019-10-30 Created: 2019-10-30 Last updated: 2024-11-20Bibliographically approved
    2. A Dedicated 21-Plex Proximity Extension Assay Panel for High-Sensitivity Protein Biomarker Detection Using Microdialysis in Severe Traumatic Brain Injury: The Next Step in Precision Medicine?
    Open this publication in new window or tab >>A Dedicated 21-Plex Proximity Extension Assay Panel for High-Sensitivity Protein Biomarker Detection Using Microdialysis in Severe Traumatic Brain Injury: The Next Step in Precision Medicine?
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    2023 (English)In: NEUROTRAUMA REPORTS, ISSN 2689-288X, Vol. 4, no 1, p. 25-40Article in journal (Refereed) Published
    Abstract [en]

    Cerebral protein profiling in traumatic brain injury (TBI) is needed to better comprehend secondary injury pathways. Cerebral microdialysis (CMD), in combination with the proximity extension assay (PEA) technique, has great potential in this field. By using PEA, we have previously screened >500 proteins from CMD samples collected from TBI patients. In this study, we customized a PEA panel prototype of 21 selected candidate protein biomarkers, involved in inflammation (13), neuroplasticity/-repair (six), and axonal injury (two). The aim was to study their temporal dynamics and relation to age, structural injury, and clinical outcome. Ten patients with severe TBI and CMD monitoring, who were treated in the Neurointensive Care Unit, Uppsala University Hospital, Sweden, were included. Hourly CMD samples were collected for up to 7 days after trauma and analyzed with the 21-plex PEA panel. Seventeen of the 21 proteins from the CMD sample analyses showed significantly different mean levels between days. Early peaks (within 48 h) were noted with interleukin (IL)-1 beta, IL-6, IL-8, granulocyte colony-stimulating factor, transforming growth factor alpha, brevican, junctional adhesion molecule B, and neurocan. C-X-C motif chemokine ligand 10 peaked after 3 days. Late peaks (>5 days) were noted with interleukin-1 receptor antagonist (IL-1ra), monocyte chemoattractant protein (MCP)-2, MCP-3, urokinase-type plasminogen activator, Dickkopf-related protein 1, and DRAXIN. IL-8, neurofilament heavy chain, and TAU were biphasic. Age (above/below 22 years) interacted with the temporal dynamics of IL-6, IL-1ra, vascular endothelial growth factor, MCP-3, and TAU. There was no association between radiological injury (Marshall grade) or clinical outcome (Extended Glasgow Outcome Scale) with the protein expression pattern. The PEA method is a highly sensitive molecular tool for protein profiling from cerebral tissue in TBI. The novel TBI dedicated 21-plex panel showed marked regulation of proteins belonging to the inflammation, plasticity/repair, and axonal injury families. The method may enable important insights into complex injury processes on a molecular level that may be of value in future efforts to tailor pharmacological TBI trials to better address specific disease processes and optimize timing of treatments.

    Place, publisher, year, edition, pages
    Mary Ann Liebert, 2023
    Keywords
    biomarker, cerebral microdialysis, neurointensive care, proximity extension assay, traumatic brain injury
    National Category
    Neurology Neurosciences
    Identifiers
    urn:nbn:se:uu:diva-497708 (URN)10.1089/neur.2022.0067 (DOI)000915436800001 ()36726870 (PubMedID)
    Note

    De tre första författarna delar förstaförfattarskapet.

    De två sista författarna delar sistaförfattarskapet.

    Available from: 2023-03-09 Created: 2023-03-09 Last updated: 2024-11-20Bibliographically approved
    3. Deciphering Proteomic Expression in Inflammatory Disorders: A Mass Spectrometry Exploration Comparing Infectious, Noninfectious, and Traumatic Brain Injuries in Human Cerebrospinal Fluid
    Open this publication in new window or tab >>Deciphering Proteomic Expression in Inflammatory Disorders: A Mass Spectrometry Exploration Comparing Infectious, Noninfectious, and Traumatic Brain Injuries in Human Cerebrospinal Fluid
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    2024 (English)In: Neurotrauma Reports, ISSN 2689-288X, Vol. 5, no 1, p. 857-873Article in journal (Refereed) Published
    Abstract [en]

    The central nervous system (CNS) evokes a complex inflammatory response to injury. Inflammatory cascades are present in traumatic, infectious, and noninfectious disorders affecting the brain. It contains a mixture of pro- andanti-inflammatory reactions involving well-known proteins, but also numerous proteins less explored in these processes. The aim of this study was to explore the distinct inflammatory response in traumatic brain injury (TBI)compared with other CNS injuries by utilization of mass-spectrometry. In total, 46 patients had their cerebrospinal fluid (CSF) analyzed with the use of mass-spectrometry. Among these, CSF was collected via an external ventricular drain (EVD) from n = 12 patients with acute TBI. The resulting protein findings were then compared with CSF obtained by lumbar puncture from n = 14 patients with noninfectious CNS disorders comprising relapsing–remitting multiple sclerosis, anti-N-methyl-D-aspartate-receptor encephalitis, acute disseminated encephalomyelitis, and n = 13 patients with progressive multifocal leukoencephalopathy, herpes simplex encephalitis, and other types ofviral meningitis. We also utilized n = 7 healthy controls (HC). In the comparison between TBI and noninfectious inflammatory CNS disorders, concentrations of 57 proteins significantly differed between the groups. Among them, 20 and 37 proteins were up- and downregulated, respectively. No proteins were uniquely identified in the TBI group. In the comparison of TBI and HC, 55 proteins were significantly different, with 24 and 31 proteins being up- and downregulated, respectively. Four proteins were uniquely identified in the TBI group, (FGG, HBA1, TKT,CA1). In the TBI versus infectious inflammatory CNS disorders, 57 proteins differed significantly between the groups, with 17 and 40 proteins being up- and down regulated, respectively. No proteins were uniquely identified in the TBI group. Due to large discrepancies between the groups compared, the following proteins were selected for further deeper analysis among those being differentially regulated: APOE, CFB, CHGA, CHI3L1, C3, FCGBP, FGA,GSN, IGFBP7, SERPINA3, SOD3, and TTR. We found distinct proteomic profiles in the CSF of TBI patients compared with HC and different disease controls, indicating a specific interplay between inflammatory factors, metabolic response, and cell integrity. In relation to primarily infectious or inflammatory disorders, unique inflammatory pathways seem to be engaged, and could potentially serve as future treatment targets.

    Place, publisher, year, edition, pages
    Mary Ann Liebert, 2024
    Keywords
    central nervous system, encephalitis, fluidic protein biomarker, human studies, inflammation, mass-spectrometry, neurointensive care, traumatic brain injury
    National Category
    Neurology
    Identifiers
    urn:nbn:se:uu:diva-539391 (URN)10.1089/neur.2024.0050 (DOI)001316175100001 ()39391051 (PubMedID)2-s2.0-85204871830 (Scopus ID)
    Available from: 2024-11-01 Created: 2024-11-01 Last updated: 2025-05-20Bibliographically approved
    4. Comparison of Mass-Spectrometry Data of Protein Expression in Patients with Severe Traumatic Brain Injury and COVID-19
    Open this publication in new window or tab >>Comparison of Mass-Spectrometry Data of Protein Expression in Patients with Severe Traumatic Brain Injury and COVID-19
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    (English)Manuscript (preprint) (Other academic)
    Keywords
    biomarkers, COVID-19, mass spectrometry, neuroinflammation, proteomics, traumatic brain injury
    National Category
    Neurosciences
    Research subject
    Medical Science
    Identifiers
    urn:nbn:se:uu:diva-543423 (URN)
    Available from: 2024-11-20 Created: 2024-11-20 Last updated: 2025-05-14
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  • Public defence: 2025-09-05 13:00 H:son Holmdahlsalen, ing. 100, 2 tr, Akademiska sjukhuset, Uppsala
    Lif, Hanna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Plastic Surgery.
    Characterisation of unicoronal synostosis for improved surgical outcomes2025Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The severity of unicoronal synostosis is highly variable, but explanatory patient- or treatment-related factors have yet to be defined. There is a lack of standardised and precise measurements to quantify severity, and severity does not traditionally influence the choice of surgical treatment approach. The aim of this thesis was to provide an objective 3D morphological characterisation of unicoronal synostosis, to investigate the relationship between morphology and function, and to assess its relevance to surgical treatment. An automatic and objective statistical shape modelling workflow was developed to quantify the severity of orbital morphology. These 3D measures were used to evaluate the effects of surgery and subsequent growth, revealing persistent asymmetry after reconstruction by fronto-orbital advancement and remodelling. The preoperative heterogenicity of the forehead, skull base and orbits was objectively characterised, and its relationship to explanatory patient-specific factors was investigated in a retrospective two-centre cohort study conducted at Necker Hospital, France, and Uppsala University Hospital, Sweden. Peri-pterionic suture fusion seemed to limit asymmetry. Severe skull base asymmetry was associated with multiple additional issues, suggesting advantages of surgical strategies that address skull base asymmetry. Associations between ophthalmological manifestations and morphological orbital severity, or globe/orbit volume relations, were investigated preoperatively and at age three to five. Postoperative improvement in symmetry was associated with reduced anisometropia but also with new-onset strabismus, implying a complex relationship between morphology and function that is not yet fully understood. The relationship between preoperative morphological severity and long-term ophthalmological outcomes was also investigated in a retrospective two-centre cohort study conducted at Necker Hospital, France, and Uppsala University Hospital, Sweden. Global shape deviation of the ipsilateral orbit preoperatively was identified as a potential predictive factor for worse functional outcome. Neither age at surgery nor contralateral morphology were found to influence long-term functional outcomes. The results suggested benefits to surgical treatment methods that address only the ipsilateral side. In conclusion, these findings indicated a need to refine and individualise surgical treatment in unicoronal synostosis, based on factors influencing severity and long-term function, to enable successful morphological and functional outcomes. Best surgical practice in unicoronal synostosis has yet to be defined.

    List of papers
    1. Persistent discrepancies in orbital morphology after surgical treatment of unicoronal craniosynostosis: a critical image-based analysis
    Open this publication in new window or tab >>Persistent discrepancies in orbital morphology after surgical treatment of unicoronal craniosynostosis: a critical image-based analysis
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    2023 (English)In: Journal of Neurosurgery: Pediatrics, ISSN 1933-0707, E-ISSN 1933-0715, Vol. 31, no 6, p. 574-583Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: Unicoronal craniosynostosis (UCS) is characterized by complex orbital deformity and is typically treated by asymmetrical fronto-orbital remodeling (FOR) during the 1st year of life. The aim of this study was to elucidate to what extent orbital morphology is corrected by surgical treatment.

    METHODS: The extent to which orbital morphology was corrected by surgical treatment was tested by analysis of differences in volume and shape between synostotic, nonsynostotic, and control orbits at two time points. In total, 147 orbits were analyzed from patient CT images obtained preoperatively (mean age 9.3 months), at follow-up (mean age 3.0 years), and in matched controls. Semiautomatic segmentation software was used to determine orbital volume. For analysis of orbital shape and asymmetry, geometrical models, signed distance maps, principal modes of variation, and three objective parameters (mean absolute distance, Hausdorff distance, and dice similarity coefficient) were generated by statistical shape modeling.

    RESULTS: Orbital volumes on both the synostotic and nonsynostotic sides were significantly smaller at follow-up than volumes in controls and significantly smaller both preoperatively and at follow-up than orbital volumes on the nonsynostotic side. Significant differences in shape were identified globally and locally, both preoperatively and at 3 years of age. Compared with controls, deviations were mostly found on the synostotic side at both time points. Asymmetry between synostotic and nonsynostotic sides was significantly decreased at follow-up, but not compared with the inherent asymmetry of controls. On a group level, the preoperative synostotic orbit was mainly expanded in the anterosuperior and anteroinferior regions and smallest on the temporal side. At follow-up, the mean synostotic orbit was still larger superiorly but also expanded in the anteroinferior temporal region. Overall, the morphology of nonsynostotic orbits was more simi-lar to that of controls than to synostotic orbits. However, the individual variation in orbital shape was greatest for nonsynostotic orbits at follow-up.

    CONCLUSIONS: In this study, the authors presented what is, to their knowledge, the first objective automatic 3D bony evaluation of orbital shape in UCS, defining in greater detail than has been done previously how synostotic orbits differ from nonsynostotic and control orbits, and how orbital shape changes from 9.3 months of age preoperatively to 3 years of age at the postoperative follow-up. Despite surgical treatment, both local and global deviations in shape persist. These findings may have implications for future directions in the development of surgical treatment. Future studies connecting orbital morphology to ophthalmic disorders, aesthetics, and genetics could provide further insight to enable better outcomes in UCS.

    Place, publisher, year, edition, pages
    Journal of Neurosurgery Publishing Group (JNSPG), 2023
    Keywords
    unicoronal craniosynostosis, fronto-orbital remodeling, outcomes, statistical shape modeling, craniofacial, surgical technique
    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-509990 (URN)10.3171/2023.1.PEDS22349 (DOI)001020180700008 ()36905670 (PubMedID)
    Available from: 2023-08-28 Created: 2023-08-28 Last updated: 2025-05-02Bibliographically approved
    2. Understanding the heterogenicity of unicoronal synostosis: A morphometric analysis of cases compared to controls
    Open this publication in new window or tab >>Understanding the heterogenicity of unicoronal synostosis: A morphometric analysis of cases compared to controls
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    2024 (English)In: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1878-0539, Vol. 99, p. 76-84Article in journal (Refereed) Published
    Abstract [en]

    Background

    Preoperative severity of unicoronal synostosis varies greatly and involves the frontal bone, skull base and orbits. Degree of deformity affects long-term morphological and functional outcomes after surgery. The aim of this study was to describe the morphological heterogenicity and investigate its relation to patient-specific factors.

    Materials and methods

    In this retrospective cohort study, non-syndromic unicoronal synostosis patients treated between 2006 and 2022 at Necker Hospital, France or Uppsala University Hospital, Sweden, were included and matched to controls. Severity of skull base, orbital and posterior skull asymmetry, degree of anterior plagiocephaly and Harlequin deformity, lateralisation, head circumference, age, timing of metopic fusion and fusion of peri-pterionic sutures were investigated.

    Results

    Ninety-five patients and ninety-three controls were included. Skull base asymmetry was linearly related to orbital asymmetry (p < 0.001), correlated with earlier CT scans (p = 0.004) and anterior (p < 0.001) and posterior (p = 0.03) plagiocephaly. Posterior plagiocephaly was more common in patients (31%) compared with controls (5%) (p < 0.001). A patent metopic suture above nine months of age was associated with severe Harlequin deformity (p = 0.04) and a lower head circumference when fused (p = 0.03). Fronto-sphenoidal suture fusion was associated with later CT scans (p < 0.001) and less skull base asymmetry (p = 0.002). Spheno-parietal fusion was correlated with decreased skull base asymmetry (p = 0.03). Right lateralisation was more common in females.

    Conclusions

    Heterogenicity of unicoronal synostosis seems to be predominantly explained by variability in skull base morphology. Peri-pterionic fusions might limit deformity.

    Place, publisher, year, edition, pages
    Elsevier, 2024
    Keywords
    Craniosynostosis, Unicoronal craniosynostosis, Dice similarity, coefficient, Symmetry, Severity
    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-545404 (URN)10.1016/j.bjps.2024.09.044 (DOI)001369171400001 ()39357137 (PubMedID)2-s2.0-85205223815 (Scopus ID)
    Funder
    EU, Horizon 2020, 825575
    Available from: 2024-12-17 Created: 2024-12-17 Last updated: 2025-05-02Bibliographically approved
    3. Variations in orbital morphology, globe:orbit volume relation, and ophthalmological outcome in unicoronal synostosis
    Open this publication in new window or tab >>Variations in orbital morphology, globe:orbit volume relation, and ophthalmological outcome in unicoronal synostosis
    2024 (English)In: Journal of Plastic Surgery and Hand Surgery, ISSN 2000-656X, E-ISSN 2000-6764, Vol. 59, p. 162-170Article in journal (Refereed) Published
    Abstract [en]

    Nonsyndromic unicoronal synostosis is associated with variability of severity in orbital morphology and ophthalmological manifestations. The relation between the two is not fully understood, nor how surgical treatment with fronto-orbital advancement and remodelling (FOAR) changes the relation.The aim of this study was to elucidate associations between ophthalmological manifestations and variations in orbital morphology and globe:orbit volume ratios preoperatively and at long-term follow-up after surgery. Twelve children referred to Uppsala Craniofacial Center who underwent computed tomography and standardized ophthalmological examinations regarding strabismus, spherical equivalent, astigmatism, anisometropia, and subnormal vision preoperatively and at 3 years of age were included. Orbits and globes were segmented. Principal component analysis elucidated morphological variation, and symmetry between orbital pairs was measured as the Dice similarity coefficient and globe:orbit volume ratios were calculated. The defined orbital shape variations were correlated with strabismus, refractive error, and subnormal vision. Different shape variations were associated with strabismus pre- and postoperatively and ipsi- and contralateral astigmatism. Greater improvement in orbital symmetry after surgery was associated with improvement in astigmatic anisometropia and new onset strabismus at follow-up. A small globe:orbit volume ratio was associated with preoperative strabismus, while the opposite was seen at follow-up. Different mechanisms seem to cause strabismus pre- and postoperatively, and FOAR might not sufficiently correct orbital morphology.

    Place, publisher, year, edition, pages
    Medical Journals Sweden, 2024
    Keywords
    Nonsyndromic unicoronal synostosis, surgical outcome, ophthalmological outcome, orbital symmetry, globe volume, imaging
    National Category
    Ophthalmology Neurology
    Identifiers
    urn:nbn:se:uu:diva-551419 (URN)10.2340/jphs.v59.42322 (DOI)001416001200002 ()39663922 (PubMedID)2-s2.0-85212459857 (Scopus ID)
    Funder
    Eye FoundationStiftelsen Kronprinsessan Margaretas arbetsnämnd för synskadadeRegion Uppsala
    Note

    De två första författarna delar förstaförfattarskapet

    De två sista författarna delar sistaförfattarskapet

    Available from: 2025-02-26 Created: 2025-02-26 Last updated: 2025-05-02Bibliographically approved
    4. Relation between preoperative orbital morphology and long-term ophthalmological outcome up to fifteen years of age in unicoronal synostosis
    Open this publication in new window or tab >>Relation between preoperative orbital morphology and long-term ophthalmological outcome up to fifteen years of age in unicoronal synostosis
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    2025 (English)In: Plastic and reconstructive surgery (1963), ISSN 0032-1052, E-ISSN 1529-4242Article in journal (Refereed) Epub ahead of print
    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-555683 (URN)10.1097/prs.0000000000012051 (DOI)
    Available from: 2025-04-30 Created: 2025-04-30 Last updated: 2025-05-02
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    UUThesis_H-Lif-2025
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