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  • 1751.
    Åberg, Karolina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Biology.
    Finding Genes for Schizophrenia2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Schizophrenia is one of our most common psychiatric diseases. It severely affects all aspects of psychological functions and results in loss of contact with reality. No cure exists and the treatments available today produce only partial relief for disease symptoms. The aim of this work is to better understand the etiology of schizophrenia by identification of candidate genes and gene pathways involved in the development of the disease.

    In a preliminarily study, the effects of medication and genetic factors were investigated in a candidate gene, serotonin 2C receptor. This study distinguished pharmacological effects, caused by neuroleptics, and/or genetic effects, caused by unique polymorphisms, from other effects responsible for mRNA expression changes on candidate genes.

    The core of the thesis describes a new candidate gene for schizophrenia, the quaking homolog, KH domain RNA binding (mouse) or QKI, located on chromosome 6q26-q27. The identification of QKI is supported by previous linkage studies, current association studies and mRNA expression studies using three different sample sets. The investigated samples included a 12-generation pedigree with 16 distantly related schizophrenic cases and their parents, 176 unrelated nuclear families with at least one affected child in each family and human brain autopsies from 55 schizophrenic cases and from 55 controls. Indirect evidence showing involvement of QKI in myelin regulation of central nervous system is presented. Myelin plays an important role in development of normal brains and disruption of QKI might lead to schizophrenia symptoms.

    In a forth sample set, including extended pedigrees originated from a geographically isolated area above the Arctic Circle, in northeast Sweden, two additional schizophrenia susceptibility loci were identified, 2q13 and 5q21. Both these regions have previously been highlighted as potential schizophrenia loci in several other investigations, including a large Finnish study. This suggests common schizophrenia susceptibility loci for Nordic populations.

    A pilot investigation including a genome wide haplotype analysis is presented. This statistical strategy could be further developed and applied to the artic Swedish families, including analysis of 900 microsatellites and 10,000 SNPs.

    These findings will facilitate the understanding of the schizophrenia etiology and may lead to development of more efficient treatments for patients that suffer from schizophrenia.

    List of papers
    1. Serotonin Receptor 2C (HTR2C) and Schizophrenia: Examination of Possible Medication and Genetic Influences on Expression Levels
    Open this publication in new window or tab >>Serotonin Receptor 2C (HTR2C) and Schizophrenia: Examination of Possible Medication and Genetic Influences on Expression Levels
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    2005 (English)In: American Journal of Medical Genetics, ISSN 0148-7299, E-ISSN 1096-8628, Vol. 134B, p. 84-89Article in journal (Refereed) Published
    Abstract [en]

    The serotonin receptor 2C (HTR2C) gene is of interest in schizophrenia due to its involvement in regulation of dopamine activity in the prefrontal cortex. We have previously reported a decreased expression of HTR2C mRNA levels in the prefrontal cortex of schizophrenia patients. The variability in mRNA expression levels is evaluated here more closely in relation to promoter haplotypes and neuroleptic treatment received by the patients. The decrease in HTR2C mRNA was present in neuroleptic treated individuals and in patients untreated at death, indicating that the lower expression is not a short-term medication effect. Three promoter polymorphisms were used to construct haplotypes. No SNP displayed genotypic or haplotypic association with the disease. Gene expression of HTR2C was not affected by haplotype and the expression decrease in schizophrenia patients was similar in all haplotype combinations (diplotypes). We conclude that the decrease in HTR2C expression in schizophrenia may be related to the disease mechanism rather than to drug treatment. The disease related changes in HTR2C expression are not related to the promoter variants typed in our sample, but could be due to other regulatory variants or trans-acting factors.

    Keywords
    mRNA expression, neuroleptic drugs, psychiatric disease, serotonin receptor 2C, promoter polymorphisms
    National Category
    Genetics
    Identifiers
    urn:nbn:se:uu:diva-93323 (URN)10.1002/ajmg.b.30151 (DOI)15717293 (PubMedID)
    Available from: 2005-09-01 Created: 2005-09-01 Last updated: 2017-12-14Bibliographically approved
    2. Reconstruction of Ancestral Haplotypes in a 12-Generation Schizophrenia Pedigree
    Open this publication in new window or tab >>Reconstruction of Ancestral Haplotypes in a 12-Generation Schizophrenia Pedigree
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    2004 (English)In: Psychiatric Genetics, ISSN 0955-8829, E-ISSN 1473-5873, Vol. 14, no 1, p. 1-8Article in journal (Refereed) Published
    Abstract [en]

    We searched for candidate chromosomal regions inherited identical by descent in 19 patients suffering from schizophrenia or schizoaffective disorder that are related 12 generations back, to an ancestral couple born in the middle of the seventeenth century. To accomplish this goal, we constructed complete chromosomal haplotypes for each patient using genotype data from 450 markers. In total, 12 haplotype regions (with sizes ranging from 0.6 to 10.9 cM) constituted by three markers each were identical in three or more of the affected individuals. The largest genomic segment was located on 6q25, a region previously shown to be significantly more frequent in patients than controls, and proposed to contain a schizophrenia susceptibility locus. For the remaining 11 candidate haplotypes, we estimated haplotype frequencies from all the 43 affected members collected from the same family and 46 unrelated control individuals. This analysis indicated that at least four of the 11 candidate haplotypes are ancestral, since the frequencies were significantly higher in patients than in controls. Five additional haplotypes showed higher estimated frequencies in the patients but the differences were not significant. Interestingly, five of these 11 genomic regions are located in, or close to, candidate regions previously suggested to contain susceptibility genes for schizophrenia. The regions are 5q21-23, 8p21-22, 10p13-15, 13q12-13 and 22q12-13. Several of these haplotypes are probably ancestral linkage disequilibrium blocks inherited from the original couple. There exists, however, the possibility that one or more of these regions harbour schizophrenia susceptibility loci that may have epistatic interactions among them.

    Keywords
    psychiatric genetics, schizophrenia, ancestral haplotypes, susceptibility loci
    National Category
    Genetics
    Identifiers
    urn:nbn:se:uu:diva-93324 (URN)10.1097/01.ypg.0000084941.07075.f9 (DOI)15091309 (PubMedID)
    Available from: 2005-09-01 Created: 2005-09-01 Last updated: 2017-12-14Bibliographically approved
    3. Human QKI, a New Candidate Gene for Schizophrenia Involved in Myelination
    Open this publication in new window or tab >>Human QKI, a New Candidate Gene for Schizophrenia Involved in Myelination
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    2005 (English)In: American journal of medical genetics. Part B, Neuropsychiatric genetics, ISSN 1552-4841, Vol. 141B, no 1, p. 84-90Article in journal (Refereed) Published
    Abstract [en]

    We have previously shown that chromosome 6q25-6q27 includes a susceptibility locus for schizophrenia in a large pedigree from northern Sweden. In this study, we fine-mapped a 10.7 Mb region, included in this locus, using 42 microsatellites or SNP markers. We found a 0.5 Mb haplotype, likely to be inherited identical by decent, within the large family that is shared among the majority of the patients (69%). A gamete competition test of this haplotype in 176 unrelated nuclear families from the same geographical area as the large family showed association to schizophrenia (empirical P-value 0.041). The only gene located in the region, the quaking homolog, KH domain RNA binding (mouse) (QKI), was investigated in human brain autopsies from 55 cases and 55 controls using a high-resolution mRNA expression analysis. Relative mRNA expression levels of two QKI splice variants were clearly downregulated in schizophrenic patients (P-value 0.0004 and 0.03, respectively). The function of QKI has not been studied in humans, but the mouse homolog is involved in neural development and myelination. In conclusion, we present evidence from three unrelated sample-sets that propose the involvement of the QKI gene in schizophrenia. The two family based studies suggest that there may be functional variants of the QKI gene that increase the susceptibility of schizophrenia in northern Sweden, whereas the case-control study suggest that splicing of the gene may be disturbed in schizophrenic patients from other geographical origins. Taken together, we propose QKI as a possible target for functional studies related to the role of myelination in schizophrenia.

    Keywords
    mRNA-expression, haplotype investigation, fine-mapping, large pedigree
    National Category
    Genetics
    Identifiers
    urn:nbn:se:uu:diva-93325 (URN)10.1002/ajmg.b.30243 (DOI)16342280 (PubMedID)
    Available from: 2005-09-01 Created: 2005-09-01 Last updated: 2010-02-02Bibliographically approved
    4. Human QKI, a potential regulator of mRNA expression of human oligodendrocyte-related genes involved in schizophrenia
    Open this publication in new window or tab >>Human QKI, a potential regulator of mRNA expression of human oligodendrocyte-related genes involved in schizophrenia
    2006 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 103, no 19, p. 7482-7487Article in journal (Refereed) Published
    Abstract [en]

    The quaking viable mouse mutation (qkv) is a deletion including the 5′ regulatory region of the quaking gene (Qki), which causes body tremor and severe dysmyelination in mouse. The function of the human quaking gene, called quaking homolog KH domain RNA-binding (mouse) (QKI), is not well known. We have previously shown that QKI is a new candidate gene for schizophrenia. Here we show that human QKI mRNA levels can account for a high proportion (47%) of normal interindividual mRNA expression variation (and covariation) of six oligodendrocyte-related genes (PLP1, MAG, MBP, TF, SOX10, and CDKN1B) in 55 human brain autopsy samples from individuals without psychiatric diagnoses. In addition, the tightly coexpressed myelin-related genes (PLP1, MAG, and TF) have decreased mRNA levels in 55 schizophrenic patients, as compared with 55 control individuals, and most of this difference (68–96%) can be explained by variation in the relative mRNA levels of QKI-7kb, the same QKI splice variant previously shown to be down-regulated in patients with schizophrenia. Taken together, our results suggest that QKI levels may regulate oligodendrocyte differentiation and maturation in human brain, in a similar way as in mouse. Moreover, we hypothesize that previously observed decreased activity of myelin-related genes in schizophrenia might be caused by disturbed QKI splicing.

    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-93326 (URN)10.1073/pnas.0601213103 (DOI)
    Available from: 2005-09-01 Created: 2005-09-01 Last updated: 2017-12-14Bibliographically approved
    5. Genome Wide Investigation of an Isolated Schizophrenia Population Using a Dense Map of Microsatellites and SNPs in Combination
    Open this publication in new window or tab >>Genome Wide Investigation of an Isolated Schizophrenia Population Using a Dense Map of Microsatellites and SNPs in Combination
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    (English)Manuscript (Other (popular science, discussion, etc.))
    National Category
    Genetics
    Identifiers
    urn:nbn:se:uu:diva-93327 (URN)
    Available from: 2005-09-01 Created: 2005-09-01 Last updated: 2010-02-02Bibliographically approved
  • 1752.
    Åberg Lindell, Matilda
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Nuclear safeguards evaluation and analysis techniques for application to nuclear fuel material in Generation IV nuclear energy systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A new generation of nuclear energy systems called Generation IV is under development to ensure that nuclear power will be a safe, reliable and sustainable energy source for the future. This thesis addresses the challenge of making future nuclear energy systems increasingly resistant to nuclear material diversion attempts.

    Several tools have been developed for structured evaluation of a system's resistance to nuclear proliferation, in order to identify areas where nuclear energy systems are the most inherently vulnerable. In this thesis, the TOPS methodology has been applied to three different fuel cycles involving a fast reactor with fuel recycling and fuel fabrication capabilities. The recycling facility, where the fuel is dissolved and undergoes chemical separation, is identified as being particularly vulnerable. Nondestructive measurements for verification of fuel assemblies in the receipt area of the recycling facility are essential, since it is the last opportunity to verify intact fuel items. Moreover, iterative evaluation of proliferation resistance by using two different assessment methodologies – TOPS and PR&PP – as suggested in this thesis, may act as an aid in facility design and for proposing safeguards implementation.

    Based on the identified need to measure irradiated fuel assemblies prior to dissolution in the recycling facility, new methods used for analyzing gamma-ray spectroscopy data using multivariate analysis methods have been investigated. Fuel parameters of modeled nuclear fuel have been determined without any reliance on operator-declared data. Nonlinear classifiers, e.g. support vector machines (SVM), have successfully been used for discrimination between uranium oxide fuels and mixed oxide fuels. Cooling time, burnup and initial fissile content have been determined using decision tree and SVM regression. The results are promising and indicate that the nuclear safeguards regime may benefit from using multivariate techniques for data analysis. It must be emphasized, however, that experimental verification of the multivariate analysis techniques is necessary.

    List of papers
    1. Assessment of proliferation resistances of aqueous reprocessing techniques using the TOPS methodology
    Open this publication in new window or tab >>Assessment of proliferation resistances of aqueous reprocessing techniques using the TOPS methodology
    2013 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 62, p. 390-397Article in journal (Refereed) Published
    Abstract [en]

    The aim of this study is to assess and compare the proliferation resistances (PR) of three possible Generation IV lead-cooled fast reactor fuel cycles, involving the reprocessing techniques Purex, Ganex and a combination of Purex, Diamex and Sanex, respectively. The examined fuel cycle stages are reactor operation, reprocessing and fuel fabrication. The TOPS methodology has been chosen for the PR assessment, and the only threat studied is the case where a technically advanced state diverts nuclear material covertly.

    According to the TOPS methodology, the facilities have been divided into segments, here roughly representing the different forms of nuclear material occurring in each examined fuel cycle stage. For each segment, various proliferation barriers have been assessed.

    The results make it possible to pinpoint where the facilities can be improved. The results show that the proliferation resistance of a fuel cycle involving recycling of minor actinides is higher than for the traditional Purex reprocessing cycle. Furthermore, for the purpose of nuclear safeguards, group actinide extraction should be preferred over reprocessing options where pure plutonium streams occur. This is due to the fact that a solution containing minor actinides is less attractive to a proliferator than a pure Pu solution. Thus, the safeguards analysis speaks in favor of Ganex as opposed to the Purex process.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    proliferation resistance, reprocessing, Generation IV, lead-cooled fast reactor
    National Category
    Other Physics Topics
    Research subject
    Physics
    Identifiers
    urn:nbn:se:uu:diva-205579 (URN)10.1016/j.anucene.2013.06.040 (DOI)000327170800046 ()
    Note

    Erratum in Annals of Nuclear Energy, 2014:66, pp 61-62, doi: 10.1016/j.anucene.2013.11.044

    Available from: 2013-08-20 Created: 2013-08-20 Last updated: 2018-04-19Bibliographically approved
    2. Schematic design and safeguards instrumentation of a Gen IV fuel recycling facility.
    Open this publication in new window or tab >>Schematic design and safeguards instrumentation of a Gen IV fuel recycling facility.
    2013 (English)Conference paper, Published paper (Other academic)
    Abstract [en]

    The sustainability criterion for Gen IV systems, inherently presumes the availability of efficient fuel recycling capabilities. Research activities concerning advanced fuel recycling are currently pursued, and one area for such research concerns safeguards aspects of recycling facilities. Since a recycling facility may be considered as sensitive from a non-proliferation perspective, it is important to address these issues early in the design process, according to the principle of Safeguards By Design.

    Presented in this paper is a suggested safeguards approach for a fuel recycling facility belonging to a small Gen IV lead-cooled fast reactor system that is under study in Sweden. A schematic design of a small-scale recycling facility, where actinides are separated using group actinide solvent extraction, is put forward. Measurement points are suggested based on available information on the recycling process activities and calculated material flows.

    Based on the identified need for measurements in the facility, possible techniques and instrumentation for measurements have been identified with the purpose to provide both inspecting parties and facility operators with necessary information for their respective needs. More generally, this type of analysis may be used to support Safeguards By Design in the planning of new recycling facilities.

    Keywords
    Gen IV, recycling, group actinide extraction, instrumentation, Safeguards By Design
    National Category
    Other Physics Topics
    Research subject
    Applied Nuclear Physics
    Identifiers
    urn:nbn:se:uu:diva-204141 (URN)
    Conference
    The 35th ESARDA Annual Meeting
    Available from: 2013-07-22 Created: 2013-07-22 Last updated: 2018-01-15
    3. Proliferation resistance assessments during the design phase of a fuel recycling facility as a means of reducing proliferation risks
    Open this publication in new window or tab >>Proliferation resistance assessments during the design phase of a fuel recycling facility as a means of reducing proliferation risks
    2013 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    The sustainability criterion for Gen IV nuclear energy systems inherently presumes the availability of efficient fuel recycling capabilities. One area for research on advanced fuel recycling concerns safeguards aspects of this type of facilities. Since a recycling facility may be considered as sensitive from a non-proliferation perspective, it is important to address these issues early in the design process, according to the principle of Safeguards By Design.

    Presented in this paper is a mode of procedure, where assessments of the proliferation resistance (PR) of a recycling facility for fast reactor fuel have been performed so as to identify the weakest barriers to proliferation of nuclear material. Two supplementing established methodologies have been applied; TOPS and PR&PP. The chosen fuel recycling facility belongs to a small Gen IV lead-cooled fast reactor system that is under study in Sweden. A schematic design of the recycling facility, where actinides are separated using solvent extraction, has been examined.

    The PR assessment methodologies make it possible to pinpoint areas in which the facility can be improved in order to reduce the risk of diversion. The initial facility design may then be slightly modified and/or safeguards measures may be introduced to reduce the total identified proliferation risk. After each modification of design and/or safeguards implementation, a new PR assessment of the revised system can been carried out. This way, each modification can be evaluated and new ways to further enhance the proliferation resistance can be identified.

    This type of iterative procedure may support Safeguards By Design in the planning of new recycling plants and other nuclear facilities.

    Keywords
    Proliferation resistance, safeguards by design, reprocessing, Generation IV
    National Category
    Other Physics Topics
    Research subject
    Physics
    Identifiers
    urn:nbn:se:uu:diva-205866 (URN)
    Conference
    GLOBAL 2013: International Nuclear Fuel Cycle Conference
    Available from: 2013-08-23 Created: 2013-08-23 Last updated: 2018-04-19Bibliographically approved
    4. Discrimination of irradiated MOX fuel from UOX fuel by multivariate statistical analysis of simulated activities of gamma-emitting isotopes
    Open this publication in new window or tab >>Discrimination of irradiated MOX fuel from UOX fuel by multivariate statistical analysis of simulated activities of gamma-emitting isotopes
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    2018 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 885, p. 67-78Article in journal (Refereed) Published
    Abstract [en]

    This paper investigates how concentrations of certain fission products and their related gamma-ray emissions can be used to discriminate between uranium oxide (UOX) and mixed oxide (MOX) type fuel. Discrimination of irradiated MOX fuel from irradiated UOX fuel is important in nuclear facilities and for transport of nuclear fuel, for purposes of both criticality safety and nuclear safeguards. Although facility operators keep records on the identity and properties of each fuel, tools for nuclear safeguards inspectors that enable independent verification of the fuel are critical in the recovery of continuity of knowledge, should it be lost. A discrimination methodology for classification of UOX and MOX fuel, based on passive gamma-ray spectroscopy data and multivariate analysis methods, is presented. Nuclear fuels and their gamma-ray emissions were simulated in the Monte Carlo code Serpent, and the resulting data was used as input to train seven different multivariate classification techniques. The trained classifiers were subsequently implemented and evaluated with respect to their capabilities to correctly predict the classes of unknown fuel items. The best results concerning successful discrimination of UOX and MOX-fuel were acquired when using non-linear classification techniques, such as the k nearest neighbors method and the Gaussian kernel support vector machine. For fuel with cooling times up to 20 years, when it is considered that gamma-rays from the isotope  134Cs can still be efficiently measured, success rates of 100% were obtained. A sensitivity analysis indicated that these methods were also robust.

    Keywords
    Spent nuclear fuel, MOX, Gamma spectroscopy, Multivariate analysis, Classification
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-337676 (URN)10.1016/j.nima.2017.12.020 (DOI)000424740800009 ()
    Funder
    Swedish Research Council, VR 621-2009-3991Swedish Radiation Safety Authority, SSM2016-661
    Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-04-19Bibliographically approved
    5. Determination of irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions
    Open this publication in new window or tab >>Determination of irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions
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    2017 (English)In: Article in journal (Refereed) Submitted
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-337677 (URN)
    Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-04-19
  • 1753.
    Åberg, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    System Effects of Improved Energy Efficiency in Swedish District-Heated Buildings2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To alleviate global warming, European-Union member states must reduce primary energy use, emit less carbon dioxide (CO2), and increase renewable energy use. Buildings constitute a great potential for energy savings, but saving energy in district-heated buildings influences combined heat and power (CHP) production, other electricity generation, and global CO2 emissions.

     

    This thesis investigates the system effects from Swedish district heating production caused by district heating demand changes due to energy conservation in buildings. The cost-optimising linear programming modelling tools MODEST and FMS, the latter developed in the context of this thesis, are used to describe present district heating production and to investigate the impact of heat-demand reductions in twelve Swedish district heating systems, four of them representing all Swedish district heating.

     

    Energy savings in district-heated, multi-family residential buildings yield a lower, more seasonally levelled district heating demand. These demand changes mainly reduce use of fossil-fuel and biomass for heat production. CHP production is significantly reduced if it supplies intermediate or peak district heating load. The αsystem value (ratio between generated CHP electricity and produced district heating) increases by demand reductions if CHP mainly supplies base district heating load. CO2 emissions due to district heat production depend on the approach used for CO2 assessment of electricity, and are generally reduced with heat demand reductions, unless the share of CHP production is large and the reduced fuel use yields smaller emission reductions than the emission increase from power production that replaces reduced CHP generation.

     

    In total, heat demand reductions reduce CO2 emissions due to Swedish district heating, and the district heating systems even constitute a carbon sink at certain energy conservation levels. If saved biomass replaces fossil fuels elsewhere, a lower heat demand reduces CO2 emissions for every studied district heating system.

    List of papers
    1. Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures in residential buildings
    Open this publication in new window or tab >>Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures in residential buildings
    2011 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, no 12, p. 7839-7852Article in journal (Refereed) Published
    Abstract [en]

    The development towards more energy efficient buildings, as well as the expansion of district heating (DH) networks, is generally considered to reduce environmental impact. But the combined effect of these two progressions is more controversial. A reduced heat demand (HD) due to higher energy efficiency in buildings might hamper co-production of electricity and DH. In Sweden, co-produced electricity is normally considered to displace electricity from less efficient European condensing power plants. In this study, a potential HD reduction due to energy efficiency measures in the existing building stock in the Swedish city Linkoping is calculated. The impact of HD reduction on heat and electricity production in the Linkoping DH system is investigated by using the energy system optimisation model MODEST. Energy efficiency measures in buildings reduce seasonal HD variations. Model results show that HD reductions primarily decrease heat-only production. The electricity-to-heat output ratio for the system is increased for HD reductions up to 30%. Local and global CO(2) emissions are reduced. If co-produced electricity replaces electricity from coal-fired condensing power plants, a 20% HD reduction is optimal for decreasing global CO(2) emissions in the analysed DH system.

    Keywords
    Low-energy residential buildings, District heating, Energy efficiency measures
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-169246 (URN)10.1016/j.enpol.2011.09.031 (DOI)000298363400036 ()
    Available from: 2012-02-27 Created: 2012-02-24 Last updated: 2017-12-07Bibliographically approved
    2. Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
    Open this publication in new window or tab >>Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
    2012 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 41, no 1, p. 525-540Article in journal (Refereed) Published
    Abstract [en]

    In the future, district heating companies in Sweden must adapt to energy efficiency measures in buildings and variable fuel and electricity prices. Swedish district heating demands are expected to decrease by 1-2% per year and electricity price variations seem to be more unpredictable in the future. A cost-optimisation model of a Swedish local district heating system is constructed using the optimisation modelling tool MODEST. A scenario for heat demand changes due to increased energy efficiency in buildings, combined with the addition of new buildings, is studied along with a sensitivity analysis for electricity price variations. Despite fears that heat demand reductions will decrease co-generation of clean electricity and cause increased global emissions, the results show that anticipated heat demand changes do not increase the studied system's primary energy use or global CO2 emissions. The results further indicate that the heat production plants and the fuels used within the system have crucial importance for the environmental impact of district heat use. Results also show that low seasonal variations in electricity price levels with relatively low winter prices promote the use of electric heat pumps. High winter prices on the other hand promote co-generation of heat and electricity in CHP plants.

    Keywords
    District heating, CHP, Building energy efficiency, CO2 emissions, Primary energy use, Electricity price variations
    National Category
    Engineering and Technology
    Research subject
    Engineering Science
    Identifiers
    urn:nbn:se:uu:diva-175624 (URN)10.1016/j.energy.2012.02.034 (DOI)000304076800058 ()
    Available from: 2012-06-12 Created: 2012-06-11 Last updated: 2017-12-07Bibliographically approved
    3. Large-scale introduction of new residential district-heating loads to increase renewable electricity generation in CHP plants
    Open this publication in new window or tab >>Large-scale introduction of new residential district-heating loads to increase renewable electricity generation in CHP plants
    2012 (English)In: Proceedings of the World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012, 2012, p. 2407-2414Conference paper, Published paper (Refereed)
    Abstract [en]

    Combined heat and power (CHP) plants enable an efficient use of low-grade energy carriers, such as domestic waste and biomass, for co-generation of district heating (DH) and electricity. Expected future building energy-efficiency improvements reduce the demand for space heating and may limit the possibilities to cogenerate electricity. The use of DH for new applications, such as household appliances, can improve conditions for co-generation of electricity. This paper investigates the future potential to increase DH demand and co-generation of electricity due to large-scale implementation of household appliances that use DH instead of electricity. The analysis is applied to the DH system in Uppsala, Sweden. Results show that co-generation of electricity and total fuel use increase with implementation of household appliances connected to a building hot water circuit (HWC). The impact on CO2 emissions depends on DH fuel mix and electricity assessment approach.

    National Category
    Energy Systems
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-174620 (URN)978-162276092-3 (ISBN)
    Conference
    World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012
    Available from: 2012-05-22 Created: 2012-05-22 Last updated: 2015-01-22Bibliographically approved
    4. Development, validation and application of a fixed district heating model structure that requires small amounts of input data
    Open this publication in new window or tab >>Development, validation and application of a fixed district heating model structure that requires small amounts of input data
    2013 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 75, p. 74-85Article in journal (Refereed) Published
    Abstract [en]

    Reducing the energy use of buildings is an important part in reaching the European energy efficiency targets. Consequently, local energy systems need to adapt to a lower demand for heating. A 90% of Swedish multi-family residential buildings use district heating (DH) produced in Sweden’s over 400 DH systems, which use different heat production technologies and fuels. DH system modelling results obtained until now are mostly for particular DH systems and cannot be easily generalised. Here, a fixed model structure (FMS) based on linear programming for cost-optimisaton studies of DH systems is developed requiring only general DH system information. A method for approximating heat demands based on local outdoor temperature data is also developed. A scenario is studied where the FMS is applied to six Swedish DH systems and heat demands are reduced due to energy efficiency improvements in buildings. The results show that the FMS is a useful tool for DH system optimisation studies and that building energy efficiency improvements lead to reduced use of fossil fuels and biomass in DH systems. Also, the share of CHP in the production mix is increased in five of the six DH systems when the heat demand is reduced.

    National Category
    Energy Systems
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-211824 (URN)10.1016/j.enconman.2013.05.032 (DOI)000326661400009 ()
    Available from: 2013-12-02 Created: 2013-12-02 Last updated: 2017-12-06Bibliographically approved
    5. Investigating the impact of heat demand reductions on Swedish district heating production using a set of typical system models
    Open this publication in new window or tab >>Investigating the impact of heat demand reductions on Swedish district heating production using a set of typical system models
    2014 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 118, p. 246-257Article in journal (Refereed) Published
    Abstract [en]

    The European Union (EU) aims at reducing its CO2 emissions and use of primary energy. The EU also aims to improve the energy efficiency in buildings and promote the use of combined heat and power (CHP) plants in district heating (DH) systems. Due to significant differences among DH systems regarding fuel use and heat production units, results for one individual DH systems are not generally valid for other DH systems. Therefore, there is a need to generally describe entire DH sectors in a way that considers the heat production plant merit-orders of the individual DH systems. Here, four models of typical DH systems are defined to represent the Swedish DH sector. A scenario for stepwise heat demand reductions due to building energy efficiency improvements is studied. The results show that heat demand reductions in Swedish DH systems generally reduce global CO2 emissions and mainly reduce the use of biomass and fossil fuels, while the use of waste and industrial waste heat (IWH) is less influenced. The results further show that in order to maximise the reduction of CO2 emissions by energy conservation in buildings, the heat production technologies of the DH system should be considered. A large share of CHP production with a high electricity-to-heat output ratio decreases the possibilities to reduce global CO2 emissions through heat demand reductions.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    district heating, heat demand, Building energy efficiency, CO2 emissions, Combined heat and power
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-219717 (URN)10.1016/j.apenergy.2013.11.077 (DOI)000332435000025 ()
    Funder
    Swedish Energy Agency
    Available from: 2014-03-05 Created: 2014-03-05 Last updated: 2017-12-05Bibliographically approved
  • 1754.
    Åberg, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Design and Synthesis of 11C-Labelled Compound Libraries for the Molecular Imaging of EGFr, VEGFr-2, AT1 and AT2 Receptors: Transition-Metal Mediated Carbonylations Using [11C]Carbon Monoxide2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This work deals with radiochemistry and new approaches to develop novel PET tracers labelled with the radionuclide 11C.

    Two methods for the synthesis of 11C-labelled acrylamides have been explored. First, [1-11C]-acrylic acid was obtained from a palladium(0)-mediated 11C-carboxylation of acetylene with [11C]carbon monoxide; this could be converted to the corresponding acyl chloride and then combined with benzylamine to form N-benzyl[carbonyl-11C]acrylamide. In the second method, the palladium(0)-mediated carbonylation of vinyl halides with [11C]carbon monoxide was explored. This latter method, yielded labelled acrylamides in a single step with retention of configuration at the C=C double bond, and required less amine compared to the acetylene method.

    The vinyl halide method was used to synthesize a library of 11C-labelled EGFr-inhibitors in 7-61% decay corrected radiochemical yield via a combinatorial approach. The compounds were designed to target either the active or the inactive form of EGFr, following computational docking studies.

    The rhodium(I)-mediated carbonylative cross-coupling of an azide and an amine was shown to be a very general reaction and was used to synthesize a library of dual VEGFr-2/PDGFrβ inhibitors that were 11C-labelled at the urea position in 38-78% dc rcy.

    The angiotensin II AT1 receptor antagonist eprosartan was 11C-labelled at one of the carboxyl groups in one step using a palladium(0)-mediated carboxylation. Autoradiography shows specific binding in rat kidney, lung and adrenal cortex, and organ distribution shows a high accumulation in the intestines, kidneys and liver. Specific binding in frozen sections of human adrenal incidentalomas warrants further investigations of this tracer.

    Three angiotensin II AT2 ligands were 11C-labelled at the amide group in a palladium(0)-mediated aminocarbonylation in 16-36% dc rcy. One of the compounds was evaluated using in vitro using autoradiography, and in vivo using organ distribution and animal PET. The compound was metabolized fast and excreted via urine. High radioactivity was also found in the liver, meaning that more metabolically stable compounds are desirable for future development.

     

    List of papers
    1. Synthesis of [11C]/[13C]acrylamides by palladium-mediated carbonylation
    Open this publication in new window or tab >>Synthesis of [11C]/[13C]acrylamides by palladium-mediated carbonylation
    2007 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 3, p. 455-461Article in journal (Refereed) Published
    Abstract [en]

    Two methods are presented for the synthesis of acrylamides labelled with C-11 (beta(+), t(1/2) = 20.4 min) and C-11 in the carbonyl position. In the first method, [1-C-11]acrylic acid is synthesised from [C-11]carbon monoxide by palladium-mediated hydroxy-carbonylation of acetylene. The labelled carboxylic acid is converted into the acyl chloride and subsequently treated with amine to yield N-benzyl[carbonyl(11)C]acrylamide, The second method utilizes [C-11]carbon monoxide in a palladium-mediated carbonylative cross-coupling of vinyl halides and amines. A higher radiochemical yield is achieved with the latter method and the amount of amine needed is decreased to 1/20. The C-11-labelled acrylamides were isolated in up to 81 % decay-corrected radiochemical yield. Starting from 10 +/- 0.5GBq of [C-11]carbon monoxide, N-benzyl[carbonyl-C-11]acrylamide was obtained in 4 min with a specific radioactivity of 330 +/- 4 GBq mu mol-(1). Co-labelling with C-11 and C-13 enabled confirmation of the labelled position by C-13 NMR spectroscopy.

    Keywords
    Carbonylation, Amides, Carbon monoxide, Isotopic labelling, Carbon-11, 11C, PET
    National Category
    Chemical Sciences
    Research subject
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98592 (URN)10.1002/ejoc.200600700 (DOI)000243600100007 ()
    Available from: 2009-02-27 Created: 2009-02-27 Last updated: 2017-12-13Bibliographically approved
    2. Synthesis of a Library of 11C-Carbonyl-labelled Irreversibly Binding EGFr Inhibitors as Potential Biomarkers for Tumours
    Open this publication in new window or tab >>Synthesis of a Library of 11C-Carbonyl-labelled Irreversibly Binding EGFr Inhibitors as Potential Biomarkers for Tumours
    (English)Manuscript (Other academic)
    Keywords
    [11C]carbon monoxide, isotopic labelling, EGFR, molecular imaging, PET, kinase, acrylamide
    National Category
    Organic Chemistry
    Research subject
    Organic Chemistry; Organic Pharmaceutical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98596 (URN)
    Available from: 2009-03-04 Created: 2009-02-27 Last updated: 2013-10-02
    3. Rhodium-mediated [11C]Carbonylation: A library of N-phenyl-N′-{4-(4-quinolyloxy)-phenyl}-[11C]-urea derivatives as potential PET angiogenic probes
    Open this publication in new window or tab >>Rhodium-mediated [11C]Carbonylation: A library of N-phenyl-N′-{4-(4-quinolyloxy)-phenyl}-[11C]-urea derivatives as potential PET angiogenic probes
    2009 (English)In: Journal of labelled compounds & radiopharmaceuticals, ISSN 0362-4803, E-ISSN 1099-1344, Vol. 52, no 5, p. 151-157Article in journal (Refereed) Published
    Abstract [en]

    As part of our ongoing investigation into the imaging of angiogenic processes, a small library of eight vascular endothelial growth factor receptor-2 (VEGFR-2)/platelet-derived growth factor receptor beta dual inhibitors based on the N-phenyl-N'-4-(4-quinolyloxy)-phenyl-urea was labelled with C-11 (beta(+), t(1/2) = 20.4 min) in the urea carbonyl position via rhodium-mediated carbonylative cross-coupling of an aryl azide and different anilines. The decay-corrected radiochemical yields of the isolated products were in the range of 38-81% calculated from [C-11]carbon monoxide. Starting with 10.7+/-0.5 GBq of [C-11]carbon monoxide, 1-[4-(6,7-dimethoxy-quinolin-4-yloxy)-3-fluoro-phenyl]-3-(4-fluoro-phenyl)-[C-11]-urea (2.1 GBq) was isolated after total reaction time of 45 min with a specific activity of 92+/-4 GBq mu mol(-1).

    Keywords
    carbonylation, carbon-11, 11C, angiogenesis, VEGFR-2, PET, kinase
    National Category
    Organic Chemistry
    Research subject
    Organic Chemistry; Organic Pharmaceutical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98593 (URN)10.1002/jlcr.1582 (DOI)000267243600003 ()
    Available from: 2009-02-27 Created: 2009-02-27 Last updated: 2017-12-13
    4. Synthesis of Asymmetric [11C]Ureas and [11C]Sulphonylureas by Rh(I)-Mediated Carbonylation
    Open this publication in new window or tab >>Synthesis of Asymmetric [11C]Ureas and [11C]Sulphonylureas by Rh(I)-Mediated Carbonylation
    (English)Manuscript (Other academic)
    Keywords
    [11C]carbon monoxide, urea, sulfonurea, tolbutamide, isotopic labelling, 11C, carbon-11
    National Category
    Organic Chemistry
    Research subject
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98598 (URN)
    Available from: 2009-03-05 Created: 2009-02-27 Last updated: 2013-10-02
    5. Synthesis and Biological Evaluation of [Carboxyl-11C]eprosartan
    Open this publication in new window or tab >>Synthesis and Biological Evaluation of [Carboxyl-11C]eprosartan
    Show others...
    2009 (English)In: Journal of labelled compounds & radiopharmaceuticals, ISSN 0362-4803, E-ISSN 1099-1344, Vol. 52, no 8, p. 295-303Article in journal (Refereed) Published
    Abstract [en]

    Essential hypertension occurs in approximately 25% of the adult population and one cause of hypertension is primary aldosteronism. Targeting the angiotensin II AT1 receptor using PET and an appropriate tracer may offer a diagnostic method for adrenocortical tissue. This report describes the synthesis of the selective AT1 receptor antagonist [carboxyl-11C]eprosartan 10, 4-[2-butyl-5-((E)-2-carboxy-3-thiophen-2-yl-propenyl)-imidazol-1-ylmethyl]-[carboxyl-11C]benzoic acid, and its precursor (E)-3-[2-butyl-3-(4-iodo-benzyl)-3H-imidazol-4-yl]-2-thiophen-2-ylmethyl-acrylic acid 9. 11C-carboxylation of the iodobenzyl moiety was performed using a palladium-mediated reaction with [11C]carbon monoxide in the presence of tetra-n-butyl-ammonium hydroxide in a micro-autoclave using a temperature gradient from 25 to 140°C over 5 min. After purification by semipreparative HPLC, [carboxyl-11C]eprosartan 10 was obtained in 37–54% decay-corrected radiochemical yield (from [11C]carbon monoxide) with a radiochemical purity >95% within 35 min of the end of bombardment (EOB). A 5-µAh bombardment gave 2.04 GBq of 10 (50% rcy from [11C]carbon monoxide) with a specific activity of 160 GBq µmol−1 at 34 min after EOB. Frozen-section autoradiography shows specific binding in kidney, lung and adrenal cortex. In vivo experiments in rats demonstrate a high accumulation in kidney, liver and intestinal wall.

    Keywords
    angiotensin II, AT1, eprosartan, [11C]carbon monoxide, carboxylation, isotopic labelling, 11C, PET
    National Category
    Organic Chemistry
    Research subject
    Organic Pharmaceutical Chemistry; Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98594 (URN)10.1002/jlcr.1598 (DOI)000268690300032 ()
    Available from: 2009-02-27 Created: 2009-02-27 Last updated: 2017-12-13Bibliographically approved
    6. Synthesis and evaluation of a 11C-labelled angiotensin II AT2 receptor ligand
    Open this publication in new window or tab >>Synthesis and evaluation of a 11C-labelled angiotensin II AT2 receptor ligand
    Show others...
    2010 (English)In: Journal of labelled compounds & radiopharmaceuticals, ISSN 0362-4803, E-ISSN 1099-1344, Vol. 53, no 10, p. 616-624Article in journal (Refereed) Published
    Abstract [en]

    Three C-11-radiolabelled high-affinity nonpeptide AT(2) receptor-selective ligands were synthesized and one of these was evaluated as positron emission tomography (PET) tracer. The labelling reaction was performed via palladium(0)-mediated aminocarbonylation of the aryl iodide substrate using [C-11] carbon monoxide as the labelled precursor. As an example, starting with 10.0 GBq [C-11] carbon monoxide, 1.10 GBq of the product N-butoxycarbonyl-3-[4-(N-benzyl-[C-11] carbamoyl)phenyl]-5-isobutylthiophene-2-sulphonamide [C-11]4d was obtained in 36% decay-corrected radiochemical yield (from [C-11] carbon monoxide), 42 min from end of bombardment with a specific activity of 110 GBq.mu mol(-1). The N-isopropyl-[C-11] carbamoyl-analogue [C-11]4c (radiochemical purity >95%) was studied employing autoradiography, organ distribution, and small animal PET. In vitro autoradiography showed specific binding in the pancreas and kidney. Organ distribution in six rats revealed a high uptake in the liver, intestine, kidney, and adrenals. Small animal PET showed rapid and reversible uptake in the kidneys followed by accumulation in the urinary bladder suggesting fast renal excretion of the tracer. In addition, high accumulation was also seen in the liver. For future studies, more metabolically stable tracers will need to be developed. To the best of our knowledge, this is the first attempt of the use of PET imaging for the detection of expressed, fully functional AT(2) receptors in living subjects.

    Keywords
    angiotensin II, AT2, PET, 11C, aminocarbonylation, [11C]carbon monoxide
    National Category
    Organic Chemistry
    Research subject
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98914 (URN)10.1002/jlcr.1793 (DOI)000282667600004 ()
    Available from: 2009-03-05 Created: 2009-03-05 Last updated: 2017-12-13Bibliographically approved
    7. Synthesis of the Aryl Iodide Precursor of [Carboxyl-11C]Candesartan
    Open this publication in new window or tab >>Synthesis of the Aryl Iodide Precursor of [Carboxyl-11C]Candesartan
    (English)Manuscript (Other academic)
    National Category
    Organic Chemistry
    Research subject
    Inorganic Chemistry; Organic Pharmaceutical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98597 (URN)
    Available from: 2009-03-04 Created: 2009-02-27 Last updated: 2013-10-02
  • 1755.
    Ågren, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    On the Formation and Structure of the Ionosphere of Titan2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    We present results on the ionospheric structure around Titan observed during numerous deep (<1000 km) flybys by the Cassini spacecraft. Our results are based on measurements by the radio and plasma wave science instrument, in particular the Langmuir probe. In addition, data from the magnetometer and electron spectrometer have contributed.

    The ionosphere of Titan is created when the atmosphere of the moon becomes ionised. There are several mechanisms that contribute to this, the most important of which are considered to be photoionisation by EUV from the Sun with associated photoelectron ionisation, and particle impact ionisation by electrons and ions from Saturn’s corotating magnetosphere.

    We investigate the influence of the solar zenith angle on the electron number density at the ionospheric peak. The results show on average four times more plasma on the dayside compared to the nightside, with typical densities of 2500 – 3500 cm-3 and 400 – 1000 cm-3, respectively. In a complementary study, we make a case study of a nightside flyby and show that the altitude structure of the deep ionosphere is reproducible by a simple electron impact ionisation model. Taken together, this leads to the conclusion that solar photons are the main ionisation source of the dayside ionosphere. However, magnetospheric particle precipitation also contributes and can explain the electron densities seen on the nightside.

    As Titan does not exhibit any large intrinsic magnetic field, the fact that it is embedded in the magnetosphere of Saturn means that the Kronian field drapes around the moon and gives rise to an induced magnetosphere. We show that there are currents of the order of 10 – 100 nA m-2 flowing in the ionosphere of the moon. Associated with the currents are perpendicular electric fields ranging from 0.5 to 3 µV m-1.

    Finally, we investigate measurements obtained during T70, the deepest Titan flyby performed to date. We show that there is a substantial amount of negative ions present below an altitude of 900 km. This confirms previous result by the electron spectrometer, showing negative ions at higher altitudes in Titan’s ionosphere.

    List of papers
    1. On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere - a Cassini case study
    Open this publication in new window or tab >>On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere - a Cassini case study
    2007 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 25, no 11, p. 2359-2369Article in journal (Refereed) Published
    Abstract [en]

    We present data from the sixth Cassini flyby of Titan (T5), showing that the magnetosphere of Saturn strongly interacts with the moon's ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement with the altitude structure of the ionosphere. Furthermore, we suggest that the dense and cold exo-ionosphere (from the exobase at 1430 km and outward to several Titan radii from the surface) can be explained by magnetospheric forcing and other transport processes whereas exospheric ionisation by impacting low energy electrons seems to play a minor role.

    Keywords
    ionosphere (Planetary ionospheres; Plasma; temperature and density); Magnetospheric physics Magnetosphere-ionosphere interactions)
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-14309 (URN)000251998900009 ()
    Available from: 2008-01-29 Created: 2008-01-29 Last updated: 2017-12-11Bibliographically approved
    2. On the ionospheric structure of Titan
    Open this publication in new window or tab >>On the ionospheric structure of Titan
    Show others...
    2009 (English)In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 57, no 14-15, p. 1821-1827Article in journal (Refereed) Published
    Abstract [en]

    In this study we present data from 17 Titan flybys showing that solar photons are the main ionisation source of Titan's dayside atmosphere. This is the first comprehensive study of Solar Zenith Angle (SZA) dependence of the electron number density and electron temperature at the ionospheric peak. The results show on average four times more plasma on the dayside compared to the nightside, with typical dayside electron densities of around 2500-3500 cm(-3) and corresponding nightside densities of around 400-1000 cm(-3). We identify a broad transition region between SZA 50 degrees and 100 degrees, where the ionosphere of Titan changes from being entirely sunlit to being in the shadow of the moon. For SZA <50 degrees the ionisation peak altitude increases with increasing SZA, whereas the transition region and the nightside show more scattered ionospheric peak altitudes. Typical electron temperatures at the ionospheric peak are 0.03-0.06 eV (approximate to 350-700 K) for both dayside and nightside. (C) 2009 Elsevier Ltd. All rights reserved.

    Keywords
    Titan, Ionospheric physics, Ionosphere-magnetosphere interaction, Cassini, SZA
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-138100 (URN)10.1016/j.pss.2009.04.012 (DOI)000273099100019 ()
    Available from: 2010-12-16 Created: 2010-12-16 Last updated: 2017-12-11Bibliographically approved