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  • 246851.
    Yu, Z
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Characterization of the precolumn BioTrap 500 C-18 for direct injection of plasma samples in a column-switching system1998In: Chromatographia, Vol. 47, p. 299-Article in journal (Refereed)
  • 246852.
    Yu, Z
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Influence of mobile phase conditions on the clean-up effect of restricted-access media precolumns for plasma samples injected in a column-switching system1997In: CHROMATOGRAPHIA, Vol. 44, p. 589-Article in journal (Refereed)
  • 246853. Yu, Ze
    et al.
    Gorlov, Mikhail
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Kloo, Lars
    Synergistic Effect of N-Methylbenzimidazole and Guanidinium Thiocyanate on the Performance of Dye-Sensitized Solar Cells Based on Ionic Liquid Electrolytes2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 50, p. 22330-22337Article in journal (Refereed)
    Abstract [en]

    The effects of additives guanidinium thiocyanate (GSCN) and N-methylbenzimidazole (MBI) on the photovoltaic performance of dye-sensitized solar cells based on low-viscous, binary ionic liquid and organic liquid electrolytes were investigated. Addition of only GSCN to the electrolyte has a pronounced influence on the short-circuit current, owing largely to the positive shift of the conduction band edge potential, probably increasing the injection efficiency of the excited dye. When only MBI was added to the electrolyte, a significant improvement of the open-circuit voltage was found, which could be attributed to a negative shift of the TiO2 conduction band edge potential and a longer electron lifetime under open-circuit conditions. Synergistic effects were observed when GSCN and MBI were used together in the ionic liquid-based electrolyte. In this case, optimal open-circuit voltage and total conversion efficiency were obtained among the ionic liquid electrolytes studied mainly due to the more efficient retardation of the recombination loss reaction at the TiO2/electrolyte interface.

  • 246854. Yu, Ze
    et al.
    Gorlov, Mikhail
    Nissfolk, Jarl
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Kloo, Lars
    Investigation of Iodine Concentration Effects in Electrolytes for Dye-Sensitized Solar Cells2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 23, p. 10612-10620Article in journal (Refereed)
    Abstract [en]

    The present work describes the effects of different iodine concentrations and iodine-to-iodide ratios in electrolytes for dye-sensitized solar cells based on low-viscous, binary ionic liquid and organic liquid solvents. Current-voltage characteristics, photoelectrochemical measurements, electrochemical impedance spectroscopy, and Raman spectroscopy were used for characterization. Optimal short-circuit current and overall conversion efficiency were achieved using intermediate and low iodine concentration in ionic liquid-based and acetonitrile-based electrolytes, respectively. Results from photoelectrochemical and Raman-spectroscopic measurements reveal that both triiodide mobility and chemical availability affect the optimal iodine concentration required in these two types of electrolytes. The higher iodine concentrations required for the ionic liquid-based electrolytes partly compensate for these effects, although negative effects from higher recombination losses and light absorption of iodine-containing species start to become significant.

  • 246855. Yu, Ze
    et al.
    Tian, Haining
    Gabrielsson, Erik
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Gorlov, Mikhail
    Sun, Licheng
    Kloo, Lars
    Tetrathiafulvalene as a one-electron iodine-free organic redox mediator in electrolytes for dye-sensitized solar cells2012In: RSC Advances, ISSN 2046-2069, Vol. 2, no 3, p. 1083-1087Article in journal (Refereed)
    Abstract [en]

    Tetrathiafulvalene (TTF) was investigated as an organic iodine-free redox mediator in electrolytes for dye-sensitized, nanocrystalline solar cells (DSCs) and was compared to the commonly used iodide/triiodide system. The TTF system studied was determined to be a one-electron transfer system, although potentially exhibiting three well-defined oxidation states. Despite the slightly positive redox potential of TTF, electrolytes with TTF displayed around 200 mV lower open-circuit voltage than the iodide/triiodide system. This can mainly be ascribed to a much shorter electron lifetime in the TiO(2) film. Mass transport limitations for redox species in TTF-based electrolytes were found to be serious. Electrochemical impedance measurements (EIS) show that the charge-transfer resistance at the counter electrode in the electrolyte with TTF is considerably larger than for the iodide/triiodide system. In addition, the light absorption of the TTF-based electrolyte is stronger than that for the iodide/triiodide system. Thus, DSCs with TTF-based electrolytes show worse photovoltaic performance than those with iodide/triiodide-based electrolytes. The differences in I-V characteristics and charge-recombination behavior have also been elucidated.

  • 246856. Yu, Ze
    et al.
    Vlachopoulos, Nick
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Gorlov, Mikhail
    Kloo, Lars
    Liquid electrolytes for dye-sensitized solar cells2011In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 40, no 40, p. 10289-10303Article in journal (Refereed)
    Abstract [en]

    The present review offers a survey of liquid electrolytes used in dye-sensitized solar cells from the beginning of photoelectrochemical cell research. It handles both the solvents employed, and the prerequisites identified for an ideal liquid solvent, as well as the various effects of electrolyte solutes in terms of redox systems and additives. The conclusions of the present review call for more detailed molecular insight into the electrolyte-electrode interface reactions and structures.

  • 246857. Yu, Ze
    et al.
    Vlachopoulos, Nick
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Kloo, Lars
    Incompletely solvated ionic liquid mixtures as electrolyte solvents for highly stable dye-sensitized solar cells2013In: RSC ADV, ISSN 2046-2069, Vol. 3, no 6, p. 1896-1901Article in journal (Refereed)
    Abstract [en]

    Ionic liquids have been intensively investigated as alternative stable electrolyte solvents for dye-sensitized solar cells (DSCs). A highest overall conversion efficiency of over 8% has been achieved using a ionic-liquid-based electrolyte in combination with an iodide/triiodide redox couple. However, the relatively high viscosities of ionic liquids require higher iodine concentration in the electrolyte due to mass-transport limitations of the triiodide ions. The higher iodine concentration significantly reduces the photovoltaic performance, which normally are lower than those using organic solvent-based electrolytes. Here, the concept of incompletely solvated ionic liquid mixtures (ISILMs) is introduced and represents a conceptually new type of electrolyte solvent for DSCs. It is found that the photovoltaic performance of ISILM-based electrolytes can rival that of organic solvent-based electrolytes. Furthermore, the vapor pressures of ISILMs are found to be considerably lower than that for pure organic solvents. Stability tests show that ISILM-based electrolytes provide highly stable DSCs under light soaking conditions. Thus, ISILM-based electrolytes offer a new platform to develop more efficient and stable DSC devices of relevance to future large-scale applications.

  • 246858.
    Yu, Zhang
    et al.
    Changchun Brother Biotech Co Ltd, Changchun 130062, Peoples R China..
    Jing, Huang
    Jilin Univ, Affiliated Hosp 1, Dept Lab, Changchun 130021, Peoples R China..
    Hongtao, Pan
    Furong, Jia
    Yuting, Jin
    Xu, Shengyuan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Venge, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Distinction between bacterial and viral infections by serum measurement of human neutrophil lipocalin (HNL) and the impact of antibody selection2016In: JIM - Journal of Immunological Methods, ISSN 0022-1759, E-ISSN 1872-7905, Vol. 432, p. 82-86Article in journal (Refereed)
    Abstract [en]

    The distinction between acute infections of bacterial or viral causes is clinically important, but often very difficult even for experienced doctors. Previous studies indicated that serum measurements of HNL (Human Neutrophil Lipocalin) might be a superior diagnostic means in this regard, but also indicated that the antibody conformation of the HNL assay might have an impact on the diagnostic performance. The aim of the present report was to examine this further. Methods: Several different (n = 24) HNL ELISA assays were developed using different combinations of monoclonal and polyclonal HNL antibodies. Sera were collected from healthy persons (n = 188) and from 155 patients with acute infections.before any antibiotics treatment. The patients were diagnosed as having bacterial (n = 69) or viral causes (n = 86) of their infections. Plasma and serum were also examined by Western blotting using HNL-specific polyclonal antibodies. Results: The optimal assay format for the distinction between bacterial and viral infection resulted in an area under the receiver operating characteristics curve (AuROC) for S-HNL of 0.98. (95% CI 0.94-1.00) as compared to 0.83 (0.76-0.88) for blood neutrophil counts and 0.69 (0.61-0.76) for S-CRP. Results also showed that different assay formats of HNL identified monomeric and dimeric HNL differently, the monomeric HNL being elevated in viral infections and the dimeric HNL being elevated in bacterial infections. Conclusion: We conclude that serum theasurement of HNL is a superior diagnostic means to distinguish between acute infections caused by bacteria or virus. For optimal clinical performance the immunoassay should address conformational epitopes in the dimeric HNL.

  • 246859.
    Yu, Zhaohua
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Damage mechanisms for near-infrared radiation induced cataract2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Purpose: 1) To estimate the threshold dose and the time evolution for cataract induction by near infrared radiation (IRR) in seconds exposure time domain; 2) to determine the ocular temperature development during the threshold exposure; 3) to investigate if near IRR induces cumulative lens damage considering irradiance exposure time reciprocity; 4) to experimentally estimate the temperature in the lens indirectly from the measurement of temperature-induced light scattering increase.

    Methods: Before exposure, 6-weeks-old albino rats were anesthetized and the pupils of both eyes were dilated. Then the animals were unilaterally exposed to 1090 nm IRR within the pupil area. Temperature was recorded with thermocouples placed in the selected positions of the eye. At the planned post-exposure time, the animal was sacrificed and the lenses were extracted for measurements of forward light scattering and macroscopic imaging (Paper I-III). In Paper IV, the lens was extracted from six-weeks-old albino Sprague-Dawley female rats and put into a temperature-controlled cuvette filled with balanced salt solution. Altogether, 80 lenses were equally divided on four temperature groups, 37, 40, 43 and 46 ºC. Each lens was exposed for 5 minutes to temperature depending on group belonging while the intensity of forward light scattering was recorded.

    Results: The in vivo exposure to 197 W/cm2 1090 nm IRR required a minimum 8 s for cataract induction. There was approximately 16 h delay between exposure and light scattering development in the lens. The same radiant exposure was found to cause a temperature increase of 10 °C at the limbus and 26 °C close to the retina. The in vivo exposure to 96 W/cm2 1090 nm IRR with exposure time up to 1 h resulted in an average temperature elevation of 7 °C at the limbus with the cornea humidified and no significant light scattering was induced one week after exposure. Arrhenius equation implies that the natural logarithm of the inclination coefficient for light scattering increase is linearly dependent on the inverse of the temperature. The proportionality constant and the intercept, estimated as CI(0.95)s, were 9.6±2.4 x103 K and 22.8±7.7. Further, it implies that if averaging 20 measurements of inclination coefficients in a new experiment at constant heat load, the confidence limits for prediction of temperature correspond to ±1.9 °C.

    Conclusions: It is indicated that IRR at 1090 nm produces thermal but not cumulatively photochemical cataract, probably by indirect heat conduction from absorption in tissues surrounding the lens. Applying the Arrhenius equation the in vivo temperature in the lens can be determined retrospectively with sufficient resolution.

    List of papers
    1. 1090 nm infrared radiation at close to threshold dose induces cataract with a time delay
    Open this publication in new window or tab >>1090 nm infrared radiation at close to threshold dose induces cataract with a time delay
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    2015 (English)In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 93, no 2, p. e118-e122Article in journal (Refereed) Published
    Abstract [en]

    Purpose

    To investigate if infrared radiation induced cataract is instant or is associatedwith a time delay between the exposure and the onset of lens light scattering after anexposure to just above threshold dose.

    Methods

    Six-weeks-old albino Sprague-Dawley female rats were unilaterally exposedto 197 W/cm2 infrared radiation at 1090 nm within the dilated pupil. In the firstexperiment, the animals were exposed with four exposure times of 5, 8, 13 and 20 s,respectively. At 24 h after exposure, the light scattering in both exposed andcontralateral not exposed lenses was measured. Based on the first experiment, fourpost exposure time groups were exposed unilaterally to 1090 nm infrared radiation of197 W/cm2 for 8 s. At 6, 18, 55 and 168 h after exposure, the light scattering in bothlenses was measured.

    Results

    A 197 W/cm2 infrared radiation induced light scattering in the lens withexposures of at least 8 s. Further, after exposure to infrared radiation of 197 W/cm2for 8 s, the light scattering increase in the lens was delayed approximately 16 h afterthe exposure.

    Conclusion

    There is a time delay between the exposure and the onset of cataract afterexposure to close to threshold dose implicating that either near infrared radiationcataract is photochemical or there is a time delay in the biological expression ofthermally induced damage.

    Keywords
    infrared radiation, forward light scattering, lens, photochemical, thermal
    National Category
    Basic Medicine Ophthalmology
    Research subject
    Ophtalmology
    Identifiers
    urn:nbn:se:uu:diva-226530 (URN)10.1111/aos.12508 (DOI)000349900200005 ()
    Available from: 2014-06-18 Created: 2014-06-18 Last updated: 2018-01-11Bibliographically approved
    2. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced
    Open this publication in new window or tab >>Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced
    Show others...
    2015 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 20, no 1, article id 015003Article in journal (Refereed) Published
    Abstract [en]

    The damage mechanism for near infrared radiation induced (IRR) cataract is unclear. Both a photochemical and a thermal mechanism were suggested.

    The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity.

    Groups of 20 rats were unilaterally exposed to 96 W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, 344 kJ/cm2 respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was measured quantitatively.

    The average maximum temperature increase for exposure time 10, 18, 33, 60 minutes was expressed as CI(0.95); 7.0±1.1, 6.8±1.1, 7.6±1.3, 7.4±1.1 ºC at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, -0.01±0.03 tEDC, respectively and no apparent morphological changes in the lens were observed.

    An exposure to 96 W/cm2 1090 nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is below 8 °C. This is consistent with a thermal damage mechanism for IRR induced cataract.

    Keywords
    infrared radiation, temperature, forward light scattering, lens
    National Category
    Ophthalmology
    Identifiers
    urn:nbn:se:uu:diva-240718 (URN)10.1117/1.JBO.20.1.015003 (DOI)000350206400007 ()25602780 (PubMedID)
    Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2017-12-05Bibliographically approved
    3. Ocular temperature elevation induced by threshold in vivo exposure to 1090 nm infrared radiation and associated heat diffusion
    Open this publication in new window or tab >>Ocular temperature elevation induced by threshold in vivo exposure to 1090 nm infrared radiation and associated heat diffusion
    Show others...
    2014 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 19, no 10, p. 105008-Article in journal (Refereed) Published
    Abstract [en]

    An in vivo exposure to 197 W/cm2 1090 nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as CI(0.95), was 11±3 ºC at the limbus, 16±6 ºC in the vitreous behind lens and 16±7 ºC on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1 ºC at the limbus and 26±11 ºC on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090 nm IRR for 8 s induces a temperature increase of 10 °C at the limbus and 26 °C close to the retina. IRR cataract is probably of thermal origin.

    Keywords
    infrared radiation, temperature, light scattering lens, heat diffusion
    National Category
    Neurosciences
    Research subject
    Ophtalmology
    Identifiers
    urn:nbn:se:uu:diva-232619 (URN)10.1117/1.JBO.19.10.105008 (DOI)000345837200015 ()
    Available from: 2014-09-22 Created: 2014-09-22 Last updated: 2018-05-16Bibliographically approved
    4. Measuring temperature in the lens during experimental heat load indirectly as light scattering increase rate
    Open this publication in new window or tab >>Measuring temperature in the lens during experimental heat load indirectly as light scattering increase rate
    2017 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 22, no 1, article id 015005Article in journal (Refereed) Published
    Abstract [en]

    The current study aims to experimentally estimate the temperature in the lens due to heat load indirectly from the measurement of increase rate of temperature-induced light scattering. The lens was extracted from Sprague-Dawley rats and put into a temperature-controlled cuvette filled with balanced salt solution. Altogether, 80 lenses were equally divided on four temperature groups. Each lens was exposed for 5 minutes to temperature depending on group belonging while the intensity of forward light scattering was recorded. The inclination coefficient of light scattering increase at the temperature 37, 40, 43, and 46 ºC was estimated as a CI(0.95), 3.1±0.8, 4.4±0.8, 5.5±0.9 and 7.0±0.8 x10-4 tEDC/s, respectively. The Arrhenius equation implies that the natural logarithm of the inclination coefficient is linearly dependent on the inverse of the temperature. The proportionality constant and the intercept were 9.6±2.4 x103 K and 22.8±7.7. The activation energy was 8.0±2.0 x101 kJ·mol-1. The current experiment implies that if averaging 20 measurements of inclination coefficients in a new experiment at constant heat load, the confidence limits for predicted temperature correspond to ±1.9 °C. With the proportionality constant and the intercept estimated in the current experiment, the in vivo temperature in the lens can be determined retrospectively with sufficient resolution.

    Keywords
    forward light scattering; lens; cataract; temperature; Arrhenius equation
    National Category
    Neurosciences
    Research subject
    Ophtalmology
    Identifiers
    urn:nbn:se:uu:diva-308820 (URN)10.1117/1.JBO.22.1.015005 (DOI)000396370600009 ()
    Available from: 2016-11-30 Created: 2016-11-30 Last updated: 2018-01-13Bibliographically approved
  • 246860.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Persson, Rolf
    Swedish Defence Research Agency.
    Öhgren, Johan
    Swedish Defence Research Agency.
    Sandberg, Stig
    Swedish Defence Research Agency.
    Hörberg, Ulf
    Swedish Defence Research Agency.
    Berglund, Folke
    Swedish Defence Research Agency.
    Karlsson, Kjell
    Swedish Defence Research Agency.
    Steinvall, Ove
    Swedish Defence Research Agency.
    Söderberg, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Green light laser exposure at 532nm near the exposure limit during a human volunteer vehicle driving task does not alter structure or function in the visual system2014In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 26, no 2, p. 022009-1-022009-7Article in journal (Refereed)
    Abstract [en]

    This study aimed to verify nonexistence of clinically important pathological effects to the visual system after exposure to 532 nm green laser light close to the exposure limit. The present medical surveillance of vision and visual health reported in this paper is the conjunction with a study of driver performance in the presence of 532 nm laser induced glare. The driving time varied between 25 and 55 s, depending on background luminance. The laser was on during the complete test drive. The peak corneal irradiance typically was 3.5Wm2 in one test drive. Considering a typical test drive, the typical time integrated corneal radiant exposure for one test drive was estimated to be 53 J/m2. The number of test drives varied among drivers but was typically 50, thus resulting in a cumulative corneal exposure dose of approximately 2.7 kJ/m2. Altogether, ten subjects were recruited according to inclusion and exclusion criteria. All ten subjects were examined for visual acuity, intraocular pressure, contrast sensitivity, color vision, monocular reading speed, and eye structure with clinical slit-lamp microscopy examination and indirect retinoscopy. All subjects were examined before exposure, immediately after exposure, and finally within an interval between 1 week and 4 weeks after exposure. There was no significant change of visual acuity, intraocular pressure, contrast sensitivity, color vision, or monocular reading speed between before and after exposure. No abnormal ocular structure was detected after exposure. This study demonstrates that close to exposure limit, exposure to 532 nm green laser light during a vehicle driving task does not induce structural or functional damage to the human visual system as observed in the interval minutes to weeks after exposure.

  • 246861.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Schulmeister, Karl
    Talebizadeh, Nooshin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Kronschläger, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Söderberg, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Ocular temperature elevation induced by threshold in vivo exposure to 1090 nm infrared radiation and associated heat diffusion2014In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 19, no 10, p. 105008-Article in journal (Refereed)
    Abstract [en]

    An in vivo exposure to 197 W/cm2 1090 nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as CI(0.95), was 11±3 ºC at the limbus, 16±6 ºC in the vitreous behind lens and 16±7 ºC on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1 ºC at the limbus and 26±11 ºC on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090 nm IRR for 8 s induces a temperature increase of 10 °C at the limbus and 26 °C close to the retina. IRR cataract is probably of thermal origin.

  • 246862.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Schulmeister, Karl
    Talebizadeh, Nooshin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Kronschläger, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Söderberg, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced2015In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 20, no 1, article id 015003Article in journal (Refereed)
    Abstract [en]

    The damage mechanism for near infrared radiation induced (IRR) cataract is unclear. Both a photochemical and a thermal mechanism were suggested.

    The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity.

    Groups of 20 rats were unilaterally exposed to 96 W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, 344 kJ/cm2 respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was measured quantitatively.

    The average maximum temperature increase for exposure time 10, 18, 33, 60 minutes was expressed as CI(0.95); 7.0±1.1, 6.8±1.1, 7.6±1.3, 7.4±1.1 ºC at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, -0.01±0.03 tEDC, respectively and no apparent morphological changes in the lens were observed.

    An exposure to 96 W/cm2 1090 nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is below 8 °C. This is consistent with a thermal damage mechanism for IRR induced cataract.

  • 246863.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Schulmeister, Karl
    Talebizadeh, Nooshin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Kronschläger, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Söderberg, Per G
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    1090 nm infrared radiation at close to threshold dose induces cataract with a time delay2015In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 93, no 2, p. e118-e122Article in journal (Refereed)
    Abstract [en]

    Purpose

    To investigate if infrared radiation induced cataract is instant or is associatedwith a time delay between the exposure and the onset of lens light scattering after anexposure to just above threshold dose.

    Methods

    Six-weeks-old albino Sprague-Dawley female rats were unilaterally exposedto 197 W/cm2 infrared radiation at 1090 nm within the dilated pupil. In the firstexperiment, the animals were exposed with four exposure times of 5, 8, 13 and 20 s,respectively. At 24 h after exposure, the light scattering in both exposed andcontralateral not exposed lenses was measured. Based on the first experiment, fourpost exposure time groups were exposed unilaterally to 1090 nm infrared radiation of197 W/cm2 for 8 s. At 6, 18, 55 and 168 h after exposure, the light scattering in bothlenses was measured.

    Results

    A 197 W/cm2 infrared radiation induced light scattering in the lens withexposures of at least 8 s. Further, after exposure to infrared radiation of 197 W/cm2for 8 s, the light scattering increase in the lens was delayed approximately 16 h afterthe exposure.

    Conclusion

    There is a time delay between the exposure and the onset of cataract afterexposure to close to threshold dose implicating that either near infrared radiationcataract is photochemical or there is a time delay in the biological expression ofthermally induced damage.

  • 246864.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Talebizadeh, Nooshin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Kronschläger, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Söderberg, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Measuring temperature in the lens during experimental heat load indirectly as light scattering increase rate2017In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 22, no 1, article id 015005Article in journal (Refereed)
    Abstract [en]

    The current study aims to experimentally estimate the temperature in the lens due to heat load indirectly from the measurement of increase rate of temperature-induced light scattering. The lens was extracted from Sprague-Dawley rats and put into a temperature-controlled cuvette filled with balanced salt solution. Altogether, 80 lenses were equally divided on four temperature groups. Each lens was exposed for 5 minutes to temperature depending on group belonging while the intensity of forward light scattering was recorded. The inclination coefficient of light scattering increase at the temperature 37, 40, 43, and 46 ºC was estimated as a CI(0.95), 3.1±0.8, 4.4±0.8, 5.5±0.9 and 7.0±0.8 x10-4 tEDC/s, respectively. The Arrhenius equation implies that the natural logarithm of the inclination coefficient is linearly dependent on the inverse of the temperature. The proportionality constant and the intercept were 9.6±2.4 x103 K and 22.8±7.7. The activation energy was 8.0±2.0 x101 kJ·mol-1. The current experiment implies that if averaging 20 measurements of inclination coefficients in a new experiment at constant heat load, the confidence limits for predicted temperature correspond to ±1.9 °C. With the proportionality constant and the intercept estimated in the current experiment, the in vivo temperature in the lens can be determined retrospectively with sufficient resolution.

  • 246865.
    Yu, Zhaohua
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Talebizadeh, Nooshin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Kronschläger, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Söderberg, Per G.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Ophthalmology.
    Indirect temperature measurement in the lens with temperature induced light scattering2016In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, no 12Article in journal (Refereed)
  • 246866.
    Yu, Zhenggang
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Informatics and Media, Media and Communication Studies.
    Living Between Two Cultures: Intercultural communication of Chinese immigrants in Uppsala2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The research has focused on Chinese immigrants in Uppsala and the purpose of the research is to find out how intercultural communication has influenced the beliefs of Chinese immigrants in Uppsala. The beliefs here refer to ideas about family, education, workplace, and the state with regard to Hofstede et al.’s dimensions of national cultures. The thesis will focus on two dimensions: power distance and masculinity versus femininity. Two main concepts that are used in the thesis are intercultural communication and acculturation. In order to understand these two concepts, different models are introduced in the thesis: Gudykunst & Kim’s (1997) intercultural communication model, John Berry’s (2005) acculturation model, and Hofstede et al.’s acculturation curve. The research has used semi-structured interview as the main methodology and the research has conducted twelve interviews. The research shows that intercultural communication has influenced the beliefs of Chinese immigrants in Uppsala with regard to family, school, workplace, and the state in power distance and masculinity versus femininity. Justifications on beliefs in family, school, workplace, and the state have been displayed in the research.

  • 246867.
    Yu, Zi Quan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Tracking individual bees in a beehive2013Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Studying and analyzing interactions among bees requires tracking and identifying each individual among hundreds of them on a complex background. Automatic tracking and identification is challenging because of the unreliable features and appearance changes. In order to map bee’s social interactions, low computational cost algorithm needs to run for a long time and process has to be done at the same time.

    We present comparison among several methods and how we stabilize the features and reduce the appearance changes. We have improved much in set-ups and made a newly designed tag. Meanwhile we have developed the prototype  of this automatic algorithm to track and identify each individual bee among hundreds of bees in a beehive over time. The rate is 15 frame per second at this stage and for the global detector  it takes around 21s to process one frame and for the local detector  it takes around 11s to process one frame. The algorithm can correctly detect 89% of around 300 tagged bees over hundreds of frames on average, but there are still around 11% misdetections.

  • 246868.
    Yu, Zuoxiang
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Chemistry.
    Direct injection of plasma samples into restricted-access media precolumns for drug analysis in column-switching systems1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the theoretical and practical aspects of using column-switching systems for direct injection of plasma samples to assay drugs at ng/ml levels. The systems utilized a restricted-access media (RAM) precolumn for the sample clean-up and trace enrichment. The separation of analytes of interest was accomplished on a reversed-phase analytical column via a switching device in the back-flush mode.

    Retention principles for the functional permission of direct injection of biological samples on RAMs were proposed. In the long course of plasma injections, RAM packings behaved distinctly different from conventional reversed-phase materials. Changes of retention, peak performance and column resistance after the injection of 10-20 ml of plasma were mainly resulted from the blockage of sealings or the adsorption of proteins on the hydrophilic layer of the packings.

    The clean-up effect, the stability of the system and the choice of UV wavelength depended on the character of the RAM packings. However, the composition of the mobile phase serving for the RAM columns could affect the plasma elution profile, the recovery of plasma matrix and column lifetime.

    Based on the developed systems, a detection limit of 10 ng/ml was obtained for the determination of weakly UV absorbing local anaesthetics with UV at 210 nm in conjunction with large volumes of plasma injection (500 _l). Analysis of methotrexate and its main metabolite in plasma was achieved with ion-pair conditions using on-line post-column photochemical reaction and fluorimetric detection. The method gave a limit of quantitation of methotrexate at 3.6 ng/ml.

  • 246869.
    Yu, ZX
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Direct injection of large volumes of plasma in a column-switching system for the analysis of local anaesthetics .1. Optimization of semi-permeable surface precolumns in the system and characterization1996In: JOURNAL OF CHROMATOGRAPHY A, Vol. 725, p. 137-Article in journal (Refereed)
  • 246870.
    Yu, ZX
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Direct injection of large volumes of plasma in a column-switching system for the analysis of local anaesthetics .2. Determination of bupivacaine in human plasma with an alkyl-diol silica precolumn1996In: JOURNAL OF CHROMATOGRAPHY A, Vol. 725, p. 149-Article in journal (Refereed)
  • 246871.
    Yu, ZX
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Ion-pair chromatography of methotrexate in a column-switching system using an alkyl-diol silica precolumn for direct injection of plasma1996In: JOURNAL OF CHROMATOGRAPHY A, Vol. 742, p. 113-Article in journal (Refereed)
  • 246872.
    Yu, ZX
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Boos, KS
    Determination of methotrexate and its metabolite 7-hydroxymethotrexate by direct injection of human plasma into a column-switching liquid chromatographic system using post-column photochemical reactio1997In: JOURNAL OF CHROMATOGRAPHY B, Vol. 689, p. 379-Article in journal (Refereed)
  • 246873.
    Yu, ZX
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Westerlund, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Boos, KS
    Evaluation of liquid chromatographic behavior of restricted-access media precolumns in the course of direct injection of large volumes of plasma samples in column-switching systems1997In: JOURNAL OF CHROMATOGRAPHY B, Vol. 704, p. 53-Article in journal (Refereed)
  • 246874.
    Yuan, Beibei
    et al.
    Division of Global Health (IHCAR), Department of Public Health, Karolinska Institutet, Stockholm, Sweden.
    Målqvist, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    Trygg, Nadja
    Division of Global Health (IHCAR), Department of Public Health, Karolinska Institutet, Stockholm, Sweden.
    Qian, Xu
    School of Public Health, Fudan University, Shanghai, China.
    Ng, Nawi
    Unit of Epidemiology and Global Health, Department of Public Health and Clinical Medicine, Faculty of Medicine, Umeå University, Sweden.
    Thomsen, Sarah
    Division of Global Health (IHCAR), Department of Public Health, Karolinska Institutet, Stockholm, Sweden.
    What interventions are effective on reducing inequalities in maternal and child health in low- and middle-income settings?: A systematic review2014In: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 14, p. 634-Article, review/survey (Refereed)
    Abstract [en]

    Background: The deadline for achieving Millennium Development Goals 4 and 5 is approaching, but inequalities between disadvantaged and other populations is a significant barrier for progress towards achieving these goals. This systematic review aims to collect evidence about the differential effects of interventions on different sociodemographic groups in order to identify interventions that were effective in reducing maternal or child health inequalities. Methods: We searched the PubMed, EMBASE and other relevant databases. The reference lists of included reviews were also screened to find more eligible studies. We included experimental or observational studies that assessed the effects of interventions on maternal and child health, but only studies that report quantitative inequality outcomes were finally included for analysis. Results: 22 articles about the effectiveness of interventions on equity in maternal and child health were finally included. These studies covered five kinds of interventions: immunization campaigns, nutrition supplement programs, health care provision improvement interventions, demand side interventions, and mixed interventions. The outcome indicators covered all MDG 4 and three MDG 5 outcomes. None of the included studies looked at equity in maternal mortality, adolescent birth rate and unmet need for family planning. The included studies reported inequalities based on gender, income, education level or comprehensive socioeconomic status. Stronger or moderate evidence showed that all kinds of the included interventions may be more effective in improving maternal or child health for those from disadvantaged groups. Conclusion: Studies about the effectiveness of interventions on equity in maternal or child health are limited. The limited evidence showed that the interventions that were effective in reducing inequity included the improvement of health care delivery by outreach methods, using human resources in local areas or provided at the community level nearest to residents and the provision of financial or knowledge support to demand side.

  • 246875.
    Yuan, Chi
    et al.
    Gotland University, School of the Humanities and Social Science.
    Tang, Shuxuan
    Gotland University, School of the Humanities and Social Science.
    Internal and external factors influencing SMEs development: a qualitative case study of import-and-export oriented SMEs in Jiangsu province of China2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The SME sector of Jiangsu Province of China contributes quite a big percentage to the GDP and solves the unemployment problem. Moreover, the import-and-export industry has been the pillar industry that boosts the development of the economy ofJiangsuProvince. With the take-off ofJiangsu’s economy, problems have also appeared; the import-and-export-oriented SMEs have been influenced by many internal and external factors, and some of the factors are: Yuan appreciation, inflation, industrial structure, skilled employees, and CRM, etc. Therefore, the thesis is going to analyze the internal and external factors that influence the development ofJiangsuimport-and-export-oriented SMEs by researching the books and articles, and make qualitative case studies to observe how these factors have influenced the case companies.

    In order to make the qualitative case analysis, the authors have travelled back toJiangsuprovince and interviewed with different SME managers with selective questions.

  • 246876. Yuan, Chunze
    et al.
    Chen, Guanying
    Prasad, Paras N.
    Ohulchanskyy, Tymish Y.
    Ning, Zhijun
    Tian, Haining
    Sun, Licheng
    Aagren, Hans.
    Use of colloidal upconversion nanocrystals for energy relay solar cell light harvesting in the near-infrared region.2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 33, p. 16709-16713Article in journal (Refereed)
    Abstract [en]

    Colloidal upconversion (UC) nanocrystals were explored as energy relay materials for dye-sensitized solar cells for the 1st time. The use of colloidal UC nanocrystals was found to significantly enhance the upconversion efficiency and improve the photocurrent of the cells for low IR irradn. intensity. UC nanocrystals of small size favor infiltration into a TiO2 film and bring higher relay efficiency. Finally, UC nanocrystals can serve as a scattering material to increase the light absorption capability of the cells and increase the overall photocurrent of the cells under simulated sunlight irradn. [on SciFinder(R)]

  • 246877. Yuan, Gao
    Effects of Posture and Embodiment on Social Distance in Human-Agent Interaction in Mixed Reality2018In: IVA '18 Proceedings of the 18th International Conference on Intelligent Virtual Agents, 2018Conference paper (Refereed)
    Abstract [en]

    Mixed reality offers new potentials for social interaction experiences with virtual agents. In addition, it can be used to experiment with the design of physical robots. However, while previous studies have investigated comfortable social distances between humans and artificial agents in real and virtual environments, there is little data with regards to mixed reality environments. In this paper, we conducted an experiment in which participants were asked to walk up to an agent to ask a question, in order to investigate the social distances maintained, as well as the subject's experience of the interaction. We manipulated both the embodiment of the agent (robot vs. human and virtual vs. physical) as well as closed vs. open posture of the agent. The virtual agent was displayed using a mixed reality headset. Our experiment involved 35 participants in a within-subject design. We show that, in the context of social interactions, mixed reality fares well against physical environments, and robots fare well against humans, barring a few technical challenges.

  • 246878.
    Yuan, Huang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Analysis and Applied Mathematics.
    Calculation of Expected Shortfall via Filtered Historical Simulation2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 246879.
    Yuan, Jinna
    et al.
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Derraik, Jose G. B.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health. Univ Auckland, Liggins Inst, Auckland, New Zealand;Univ Auckland, Natl Sci Challenge, Auckland, New Zealand.
    Fu, Junfen
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Dong, Guanping
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Cutfield, Wayne S.
    Univ Auckland, Liggins Inst, Auckland, New Zealand;Univ Auckland, Natl Sci Challenge, Auckland, New Zealand.
    Wu, Wei
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Huang, Ke
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Jiang, Youjun
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Chen, Xiaochun
    Zhejiang Univ, Childrens Hosp, Endocrinol Dept, Sch Med, Hangzhou, Zhejiang, Peoples R China.
    Beta-Cell Function in Chinese Youngsters with Type 1 Diabetes and Assessment of Surrogate Markers of Severe Insulin Deficiency2018In: Hormone Research in Paediatrics, ISSN 1663-2818, E-ISSN 1663-2826, Vol. 90, p. 644-644Article in journal (Other academic)
  • 246880. Yuan, Ke-Hai
    et al.
    Wallentin, Fan Yang
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Statistics.
    Bentler, Peter M.
    ML Versus MI for Missing Data With Violation of Distribution Conditions2012In: Sociological Methods & Research, ISSN 0049-1241, E-ISSN 1552-8294, Vol. 41, no 4, p. 598-629Article in journal (Refereed)
    Abstract [en]

    Normal-distribution-based maximum likelihood (ML) and multiple imputation (MI) are the two major procedures for missing data analysis. This article compares the two procedures with respects to bias and efficiency of parameter estimates. It also compares formula-based standard errors (SEs) for each procedure against the corresponding empirical SEs. The results indicate that parameter estimates by MI tend to be less efficient than those by ML; and the estimates of variance -covariance parameters by MI are also more biased. In particular, when the population for the observed variables possesses heavy tails, estimates of variance -covariance parameters by MI may contain severe bias even at relative large sample sizes. Although performing a lot better, ML parameter estimates may also contain substantial bias at smaller sample sizes. The results also indicate that, when the underlying population is close to normally distributed, SEs based on the sandwich-type covariance matrix and those based on the observed information matrix are very comparable to empirical SEs with either ML or MI. When the underlying distribution has heavier tails, SEs based on the sandwich-type covariance matrix for ML estimates are more reliable than those based on the observed information matrix. Both empirical results and analysis show that neither SEs based on the observed information matrix nor those based on the sandwich-type covariance matrix can provide consistent SEs in MI. Thus, ML is preferable to MI in practice, although parameter estimates by MI might still be consistent.

  • 246881.
    Yuan, P-Q
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Granas, C
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Kallstrom, L
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Yu, J
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Huhman, K
    Larhammar, D
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Albers, H E
    Johnson, A E
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Differential distribution of the Glutamatic acid decarboxylase-65 and Glutamatic acid decarboxylase-67 messenger RNAs in the entopeduncular nucleus of the rat1997In: Neuroscience, Vol. 78, p. 87-Article in journal (Refereed)
  • 246882. Yuan, Q P
    et al.
    Lindblad-Toh, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Zander, Cecilia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology, Medical Genetics.
    Burgess, C
    Durr, A
    Schalling, M
    A cloning strategy for identification of genes containing trinucleotide repeat expansions2001In: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 8, no 4, p. 427-431Article in journal (Refereed)
    Abstract [en]

    Until today, nineteen trinucleotide repeat expansions larger than forty repeat copies have been found in the human genome. Of these, the CAG/CTG repeat is predominant motif with twelve loci identified, ten of which have been associated with the development of neurodegenerative diseases. We have developed a cloning approach which isolates disease genes containing trinucleotide repeat expansions. The method is based on size separation of genomic fragments, followed by subcloning and library hybridization with an oligonucleotide probe. Fractions and clones containing expanded repeats are identified by the repeat expansion detection (RED) method throughout the cloning procedure. Large family materials are not required and as little as 10 microg genomic DNA from a single individual is sufficient for this method. Using this strategy we have cloned two DNA fragments containing expanded repeats from two unrelated patients with a clinical diagnosis of cerebellar ataxia. Sequencing of the two fragments showed sequence identities with two disease genes, the Huntington gene and the ataxin 3 gene, respectively. The method should be adaptable to the cloning of any long repeat motif in any species. Furthermore the experimental steps can be performed in less than a month, making it very effective and time efficient to disease gene identification.

  • 246883. Yuan, S
    et al.
    Blomstrom-Lundqvist, C
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Pehrson, S
    Pripp, C M
    Wohlfart, B
    Olsson, S B
    Dispersion of repolarization following double and triple programmed stimulation. A clinical study using the monophasic action potential recording technique.1996In: Eur Heart J, ISSN 0195-668X, Vol. 17, no 7, p. 1080-91Article in journal (Refereed)
  • 246884. Yuan, S
    et al.
    Blomstrom-Lundqvist, C
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Pehrson, S
    Pripp, C-M
    Wohlfart, B
    Olsson, SB
    Dispersion of repolarization following double and triple programmed stimulation. A clinical study using the monophasic action potential recording technique.1996In: European Heart Journal, Vol. 17, p. 1080-Article in journal (Refereed)
  • 246885. Yuan, S
    et al.
    Blomstrom-Lundqvist, C
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Pripp, CM
    Pehrson, S
    Wohlfart, B
    Olsson, SB
    Signed value of monophasic action potential duration difference - A useful measure in evaluation of dispersion of repolarization in patients with ventricular arrhythmias1997In: European Heart Journal, Vol. 18, p. 1329-Article in journal (Refereed)
  • 246886. Yuan, S
    et al.
    Blomström-Lundqvist, Carina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Olsson, S B
    Monophasic action potentials: concepts to practical applications1994In: Cardiovascular Electrophysiology, ISSN 1045-3873, E-ISSN 1540-8167, Vol. 5, no 3, p. 287-308Article in journal (Refereed)
    Abstract [en]

    Monophasic Action Potentials. Monophaisc action potential (MAP) recordings reproduce the repolarization time course of intrucellular action potentials with high accuracy and provide precise information on the local activation time. With the advantage of in vivo application and the development of the safer and simpler contact catheter technique, MAP recording has become the method of choice for evaluating myocardial repolarization changes. This review aims to provide information on practical application of MAP recording in the clinical setting. MAPs can easily be recorded from the endocardium with the contact catheter technique in the electrophysiology laboratory and from the epicardium with electrode probes during open heart surgery. The technical aspects are described in detail. The rate dependence of myocardial excitability and repolarization and the effect of antiarrhythmic drugs on MAP duration and effective refractory period are thoroughly reviewed. The use of MAPs in detecting myocardial ischemia, in studying early afterdepolarization and triggered arrhythmias, in measuring dispersion of repolarization, in identifying intracardiac conduction and the development of the T wave, and in verifying the arrhythmogenic effect of mechanoelectric feedback are presented. Computerized automatic analysis of MAPs and the limitations of the MAP technique are also discussed.

  • 246887.
    Yuan, S
    et al.
    Uppsala University.
    Wohlfart, B
    Uppsala University.
    Olsson, B
    Uppsala University.
    Blomstrom-Lundqvist, C
    Uppsala University.
    Clinical Application of a Microcomputer System for Analysis of Monophasic Action Potentials1996In: PACE, Vol. 19, p. 297-Article in journal (Refereed)
  • 246888. Yuan, S
    et al.
    Wohlfart, B
    Olsson, S B
    Blomström-Lundqvist, C
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    The dispersion of repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle1995In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 16, no 1, p. 68-76Article in journal (Refereed)
    Abstract [en]

    The role of increased dispersion of repolarization in the genesis of torsade de pointes and ventricular fibrillation has been well recognized generally, but not in the genesis of monomorphic ventricular tachycardia (VT). Monophasic action potentials (MAP) were therefore recorded simultaneously from the right ventricular (RV) apex (RVA) and outflow tract (RVOT) during sinus rhythm, RV pacing and programmed extra stimulation (PES) in 24 patients with VT. The activation time (AT), MAP duration at 90% repolarization (MAPd), and repolarization time (RT) were measured and their dispersions, defined as the differences in these parameters between RVA and RVOT, were calculated. During sinus rhythm and RV pacing, the dispersions of AT, MAPd and RT (dispersions) were significantly larger in the 17 patients with a VT induced than in those without. During PES, the dispersions were further augmented in the S2 beats in the seven patients with a sustained VT induced, the maximal dispersion of RT being 85 +/- 22 ms. Both the dispersion of AT and that of MAPd contributed to the dispersion of RT. In both of our two patients with a sustained VT induced during MAP recording, a marked increase in dispersions of RT (140 and 190 ms, respectively) was observed immediately before the initiation of the VT. A link between the dispersions and the inducibility of a monomorphic VT was found in our patients, which suggests that the increased dispersions play an important role in the genesis of a monomorphic VT.

  • 246889. Yuan, S
    et al.
    Wohlfart, B
    Rasmussen, H S
    Olsson, S
    Blomström-Lundqvist, C
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Effect of dofetilide on cardiac repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle.1994In: Eur Heart J, ISSN 0195-668X, Vol. 15, no 4, p. 514-22Article in journal (Refereed)
  • 246890.
    Yuan, Xiaotian
    et al.
    Karolinska Inst, Div Hematol, Dept Med, SE-17176 Stockholm, Sweden;Karolinska Inst, Ctr Mol Med, SE-17176 Stockholm, Sweden;Karolinska Univ Hosp Solna, SE-17176 Stockholm, Sweden.
    Kronstrom, Magnus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism.
    Hellenius, Mai-Lis
    Karolinska Univ Hosp, Karolinska Inst, Dept Med, SE-17176 Solna, Sweden.
    Cederholm, Tommy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism.
    Xu, Dawei
    Karolinska Inst, Div Hematol, Dept Med, SE-17176 Stockholm, Sweden;Karolinska Inst, Ctr Mol Med, SE-17176 Stockholm, Sweden;Karolinska Univ Hosp Solna, SE-17176 Stockholm, Sweden.
    Sjögren, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism.
    Longitudinal changes in leukocyte telomere length and mortality in elderly Swedish men2018In: Aging, ISSN 1945-4589, E-ISSN 1945-4589, Vol. 10, no 10, p. 3005-3016Article in journal (Refereed)
    Abstract [en]

    Telomere length (TL) is considered an indicator of aging and age-related diseases, but longitudinal studies on TL changes and mortality are few. We therefore analyzed TL and longitudinal changes in TL in relation to all-cause, cardiovascular, and cancer mortality in 247 elderly Swedish men. TL was determined by the qPCR method at ages 71 and 81 and subsequent mortality cases were identified from the Swedish cause-of-death registry. Cox proportional hazard ratios were calculated during a mean follow-up of 7.4 years, during which 178 deaths occurred. Short telomeres at baseline was strongly associated with mortality risks, with a 40 to 70% increased risk of all-cause mortality, and a 2-fold increased risk of cancer mortality. Longitudinal changes in TL revealed shortening in 83% of individuals, whilst 10% extended their telomeres. TL attrition did not predict all-cause or cancer mortality, but we found a 60% decreased risk for cardiovascular mortality in those who shortened their telomeres. Our data show an increased risk of mortality in individuals with short baseline telomeres, but no relations to all-cause, and cancer mortality for changes in TL. Intriguingly, our data indicate lower risk of cardiovascular mortality with shortening of telomeres. The latter should be interpreted cautiously.

  • 246891.
    Yuan, Zhiqian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    GUI for Mail-merge using Erlang and Erlguten2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Klarna AB is a financial company, it provides payment solutions for the ecommerce sector, so that they need to generate a lot of invoices everyday, which involves a large amount of tedious work, thus they need a tool to facilitate this task. The new method of invoice generating consists of two subprocess, i.e. designing templates and make mail-merging between templates and userdata.

    This project aims to implement a system to solve the issues described above, it mainly targets on the mailmerging of templates and userdata, besides it also provides a prototype of GUI for designing the templates. The final goal is to realize the automation of invoice generating to the greatest extent, later in this report I will illustrate how far this goal is reached.

    This system involves many techniques, the techniques mainly used are Erlang, Erlguten, Cappuccino framework, javascript, rubyonrails etc.

  • 246892. Yubero-Serrano, Elena M
    et al.
    Delgado-Lista, Javier
    Tierney, Audrey C
    Perez-Martinez, Pablo
    Garcia-Rios, Antonio
    Alcala-Diaz, Juan F
    Castaño, Justo P
    Tinahones, Francisco J
    Drevon, Christian A
    Defoort, Catherine
    Blaak, Ellen E
    Dembinska-Kieć, Aldona
    Risérus, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism.
    Lovegrove, Julie A
    Perez-Jimenez, Francisco
    Roche, Helen M
    Lopez-Miranda, Jose
    Insulin resistance determines a differential response to changes in dietary fat modification on metabolic syndrome risk factors: the LIPGENE study2015In: American Journal of Clinical Nutrition, ISSN 0002-9165, E-ISSN 1938-3207, Vol. 102, no 6, p. 1509-1517Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Previous data support the benefits of reducing dietary saturated fatty acids (SFAs) on insulin resistance (IR) and other metabolic risk factors. However, whether the IR status of those suffering from metabolic syndrome (MetS) affects this response is not established.

    OBJECTIVE: Our objective was to determine whether the degree of IR influences the effect of substituting high-saturated fatty acid (HSFA) diets by isoenergetic alterations in the quality and quantity of dietary fat on MetS risk factors.

    DESIGN: In this single-blind, parallel, controlled, dietary intervention study, MetS subjects (n = 472) from 8 European countries classified by different IR levels according to homeostasis model assessment of insulin resistance (HOMA-IR) were randomly assigned to 4 diets: an HSFA diet; a high-monounsaturated fatty acid (HMUFA) diet; a low-fat, high-complex carbohydrate (LFHCC) diet supplemented with long-chain n-3 polyunsaturated fatty acids (1.2 g/d); or an LFHCC diet supplemented with placebo for 12 wk (control). Anthropometric, lipid, inflammatory, and IR markers were determined.

    RESULTS: Insulin-resistant MetS subjects with the highest HOMA-IR improved IR, with reduced insulin and HOMA-IR concentrations after consumption of the HMUFA and LFHCC n-3 diets (P < 0.05). In contrast, subjects with lower HOMA-IR showed reduced body mass index and waist circumference after consumption of the LFHCC control and LFHCC n-3 diets and increased HDL cholesterol concentrations after consumption of the HMUFA and HSFA diets (P < 0.05). MetS subjects with a low to medium HOMA-IR exhibited reduced blood pressure, triglyceride, and LDL cholesterol levels after the LFHCC n-3 diet and increased apolipoprotein A-I concentrations after consumption of the HMUFA and HSFA diets (all P < 0.05).

    CONCLUSIONS: Insulin-resistant MetS subjects with more metabolic complications responded differently to dietary fat modification, being more susceptible to a health effect from the substitution of SFAs in the HMUFA and LFHCC n-3 diets. Conversely, MetS subjects without IR may be more sensitive to the detrimental effects of HSFA intake. The metabolic phenotype of subjects clearly determines response to the quantity and quality of dietary fat on MetS risk factors, which suggests that targeted and personalized dietary therapies may be of value for its different metabolic features. This study was registered at clinicaltrials.gov as NCT00429195.

  • 246893.
    Yudin, Dmitry
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Trends in Magnetism: From Strong Correlations to “-onics” Technology2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Despite of enormous progress in experimental nanophysics theoretical studies of low-dimensional electron systems still remains a challenging task. Indeed, most of the structures are strongly correlated, so that an effective perturbative treatment is impossible due to the lack of a small parameter. The problem can be partly solved within the dynamical mean-field theory (DMFT) paradigm, nevertheless the correlations in physically relevant high-temperature superconductors are of purely non-local nature. The recently developed dual fermion approximation, combining field-theoretical diagram technique and numerical methods, allows for explicit account of spatial correlations. The approximation was shown to be of fastest convergence compared with standard DMFT extensions, and along with renormalization group is used here to study Fermi condensation on a triangular lattice near van Hove singularities. The still debated phenomenon of Fermi condensation is believed to be a precursor to strongly correlated low-temperature instability and is found in this thesis to be robust even at high temperature, making its experimental verification feasible. Unlike homogeneous ferromagnetic ordering a variety of non-collinear ground state configurations emerge as a result of competition among exchange, anisotropy, and dipole-dipole interaction. These particle-like states, e.g. magnetic soliton, skyrmion, domain wall, form a spatially localized clot of magnetic energy. Consistent study of spin, which essentially is a quantum mechanical entity, led to the emergence of spintronics (spin-based electronics) and magnonics (photonics with spin waves), in the meanwhile topologically protected magnetic solitons and skyrmions might potentially be applied for data processing and information storage in next generation of electronic technology (rapidly advancing solitonics and skyrmionics). An ability to easily create, address, and manipulate such structures is among the prerequisite forming a basis of "-onics" technology. It is shown here that spins on a kagome lattice, interacting via Heisenberg exchange and Dzyaloshinskii-Moriya coupling, allow the formation of topologically protected edge states through which a skyrmion can propagate. Not only can chemical methods be used to design novel functionality, but also geometric structuring. It is demonstrated that for graphene sandwiched between two insulating media external circularly-polarized light serves as an effective magnetic field. The direct practical implication permits to control light polarization and induce spin-waves propagating on the surface of e.g. a topological insulator. The newly discovered Dirac materials, graphene and three-dimensional topological insulators, are not easy to handle. In fact, the quasiparticle band function is gapless preventing them from being used in integrated circuits, nevertheless the problem is shown here to be partially relaxed by placing a vacancy on top of it. 

    List of papers
    1. Fermi Condensation Near van Hove Singularities Within the Hubbard Model on the Triangular Lattice
    Open this publication in new window or tab >>Fermi Condensation Near van Hove Singularities Within the Hubbard Model on the Triangular Lattice
    Show others...
    2014 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 7, p. 070403-Article in journal (Refereed) Published
    Abstract [en]

    The proximity of the Fermi surface to van Hove singularities drastically enhances interaction effects and leads to essentially new physics. In this work we address the formation of flat bands ("Fermi condensation") within the Hubbard model on the triangular lattice and provide a detailed analysis from an analytical and numerical perspective. To describe the effect we consider both weak-coupling and strong-coupling approaches, namely the renormalization group and dual fermion methods. It is shown that the band flattening is driven by correlations and is well pronounced even at sufficiently high temperatures, of the order of 0.1-0.2 of the hopping parameter. The effect can therefore be probed in experiments with ultracold fermions in optical lattices.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-220984 (URN)10.1103/PhysRevLett.112.070403 (DOI)000331953300003 ()
    Available from: 2014-03-25 Created: 2014-03-24 Last updated: 2017-12-05Bibliographically approved
    2. Topological excitations in a kagome magnet
    Open this publication in new window or tab >>Topological excitations in a kagome magnet
    Show others...
    2014 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, p. 4815-Article in journal (Refereed) Published
    Abstract [en]

    Chirality-that is, left or right handedness-is present in many scientific areas, and particularly in condensed matter physics. Inversion symmetry breaking relates chirality with skyrmions, which are protected field configurations with particle-like and topological properties. Here we show that a kagome magnet, with Heisenberg and Dzyaloshinskii-Moriya interactions, causes non-trivial topological and chiral magnetic properties. We also find that under special circumstances, skyrmions emerge as excitations, having stability even at room temperature. Chiral magnonic edge states of a kagome magnet offer, in addition, a promising way to create, control and manipulate skyrmions. This has potential for applications in spintronics, that is, for information storage or as logic devices. Collisions between these particle-like excitations are found to be elastic at very low temperature in the skyrmion-skyrmion channel, albeit without mass-conservation. Skyrmion-antiskyrmion collisions are found to be more complex, where annihilation and creation of these objects have a distinct non-local nature.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-236091 (URN)10.1038/ncomms5815 (DOI)000342929000005 ()
    Available from: 2014-11-14 Created: 2014-11-12 Last updated: 2017-12-05
    3. Spontaneous gap generation on the surface of weakly interacting topological insulators using nonmagnetic impurities
    Open this publication in new window or tab >>Spontaneous gap generation on the surface of weakly interacting topological insulators using nonmagnetic impurities
    2014 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 90, no 16, p. 161413-Article in journal (Refereed) Published
    Abstract [en]

    Strong nonmagnetic impurities on the surface of three-dimensional topological insulators (TIs) generate localized resonance peaks close to the Dirac point. We show that this results in a strongly reduced critical Coulomb interaction strength to reach a magnetic surface state, following a Stoner-like criterion. Thus even weakly interacting TIs host a finite (local) magnetization around strong nonmagnetic impurities. The local magnetization gives rise to a global energy gap, linearly dependent on the maximum value of the magnetization but decreasing with reduced impurity concentration.

    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-238174 (URN)10.1103/PhysRevB.90.161413 (DOI)000344032300002 ()
    Available from: 2014-12-10 Created: 2014-12-10 Last updated: 2017-12-05Bibliographically approved
    4. Dynamics of quasiparticles in graphene under intense circularly polarized light
    Open this publication in new window or tab >>Dynamics of quasiparticles in graphene under intense circularly polarized light
    2015 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 91, no 7, article id 075419Article in journal (Refereed) Published
    Abstract [en]

    A monolayer of graphene irradiated with circularly polarized light suggests a unique platform for surface electromagnetic wave (plasmon-polariton) manipulation. In fact, the time periodicity of the Hamiltonian leads to a geometric Aharonov-Anandan phase and results in a photovoltaic Hall effect in graphene, creating off-diagonal components of the conductivity tensor. The latter drastically changes the dispersion relation of surface plasmon-polaritons, leading to hybrid wave generation. In this paper we present a systematic and self-contained analysis of the hybrid surface waves obtained from Maxwell equations based on a microscopic formula for the conductivity. We consider a practical example of graphene sandwiched between two dielectric media and show that in the one-photon approximation there is formation of propagating hybrid surface waves. From this analysis emerges the possibility of a reliable experimental realization to study Zitterbewegung of charge carriers of graphene.

    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-238176 (URN)10.1103/PhysRevB.91.075419 (DOI)000350252000005 ()
    Funder
    Swedish Research Council
    Available from: 2014-12-10 Created: 2014-12-10 Last updated: 2017-12-05Bibliographically approved
  • 246894.
    Yudin, Dmitry
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Katsnelson, Mikhail I.
    Radboud University Nijmegen.
    Dynamics of quasiparticles in graphene under intense circularly polarized light2015In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 91, no 7, article id 075419Article in journal (Refereed)
    Abstract [en]

    A monolayer of graphene irradiated with circularly polarized light suggests a unique platform for surface electromagnetic wave (plasmon-polariton) manipulation. In fact, the time periodicity of the Hamiltonian leads to a geometric Aharonov-Anandan phase and results in a photovoltaic Hall effect in graphene, creating off-diagonal components of the conductivity tensor. The latter drastically changes the dispersion relation of surface plasmon-polaritons, leading to hybrid wave generation. In this paper we present a systematic and self-contained analysis of the hybrid surface waves obtained from Maxwell equations based on a microscopic formula for the conductivity. We consider a practical example of graphene sandwiched between two dielectric media and show that in the one-photon approximation there is formation of propagating hybrid surface waves. From this analysis emerges the possibility of a reliable experimental realization to study Zitterbewegung of charge carriers of graphene.

  • 246895.
    Yudin, Dmitry
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hirschmeier, Daniel
    Hafermann, Hartmut
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lichtenstein, Alexander I.
    Katsnelson, Mikhail I.
    Fermi Condensation Near van Hove Singularities Within the Hubbard Model on the Triangular Lattice2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 7, p. 070403-Article in journal (Refereed)
    Abstract [en]

    The proximity of the Fermi surface to van Hove singularities drastically enhances interaction effects and leads to essentially new physics. In this work we address the formation of flat bands ("Fermi condensation") within the Hubbard model on the triangular lattice and provide a detailed analysis from an analytical and numerical perspective. To describe the effect we consider both weak-coupling and strong-coupling approaches, namely the renormalization group and dual fermion methods. It is shown that the band flattening is driven by correlations and is well pronounced even at sufficiently high temperatures, of the order of 0.1-0.2 of the hopping parameter. The effect can therefore be probed in experiments with ultracold fermions in optical lattices.

  • 246896. Yue,
    et al.
    Zhong,
    Tybring,
    Dalen,
    Dahl, Marja-Liisa
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Bertilsson,
    Sjoqvist,
    Pharmacokinetics of nortriptyline and its 10-hydroxy metabolite in Chinese subjects of different CYP2D6 genotypes1998In: Clin Pharmacol Ther, Vol. 64, p. 384-Article in journal (Refereed)
  • 246897.
    Yue, Bai-Gong
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Regulation of adenovirus alternative pre-mRNA splicing: Functional characterization of exonic and intronic splicing enhancer elements2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Pre-mRNA splicing and alternative pre-mRNA splicing are key regulatory steps controlling geneexpression in higher eukaryotes. The work in this thesis was focused on a characterization of thesignificance of exonic and intronic splicing enhancer elements for pre-mRNA splicing.

    Previous studies have shown that removal of introns with weak and regulated splice sitesrequire a splicing enhancer for activity. Here we extended these studies by demonstrating thattwo "strong" constitutively active introns, the adenovirus 52,55K and the Drosophila Ftzintrons, are absolutely dependent on a downstream splicing enhancer for activity in vitro.

    Two types splicing enhancers were shown to perform redundant functions as activators ofSplicing. Thus, SR protein binding to an exonic splicing enhancer element or U1 snRNP bindingto a downstream 5'splice site independently stimulated upstream intron removal. The datafurther showed that a 5'splice site was more effective and more versatile in activating splicing.Collectively the data suggest that a U1 enhancer is the prototypical enhancer element activatingsplicing of constitutively active introns.

    Adenovirus IIIa pre-mRNA splicing is enhanced more than 200-fold in infected extracts. Themajor enhancer element responsible for this activation was shown to consist of the IIIa branchsite/polypyrimidne tract region. It functions as a Janus element and blocks splicing in extractsfrom uninfected cells while functioning as a splicing enhancer in the context of infected extracts.

    Phosphorylated SR proteins are essential for pre-mRNA splicing. Large amount recombinantSR proteins are needed in splicing studies. A novel expression system was developed to expressphosphorylated, soluble and functionally active ASF/SF2 in E. Coli.

  • 246898.
    Yue, Bai-Gong
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ajuh, Paul
    Akusjärvi, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Lamond, AI
    Kreivi, Jan-Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Functional coexpression of serine protein kinase SRPK1 and its substrateASF/SF2 in Escherichia coli2000In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 28, no 5, p. e14-Article in journal (Refereed)
    Abstract [en]

    Mammalian proteins expressed in Escherichia coli are used in a variety of applications. A major drawback in producing eukaryotic proteins in E.coli is that the bacteria lack most eukaryotic post-translational modification systems, including serine/threonine protein kinase(s). Here we show that a eukaryotic protein can be phosphorylated in E.coli by simultaneous expression of a mammalian protein kinase and its substrate. We show that in bacteria expressing SRPK1, ASF/SF2 becomes phosphorylated to a degree resembling native ASF/SF2 present in interphase HeLa cell nuclei. The E.coli phosphorylated ASF/SF2 is functional in splicing and, contrary to the unphosphorylated protein, soluble under native conditions.

  • 246899.
    Yue, Bai-Gong
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Akusjärvi, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    A downstream splicing enhancer is essential for in vitro pre-mRNA splicing1999In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 451, no 1, p. 10-14Article in journal (Refereed)
    Abstract [en]

    Splicing enhancers have previously been shown to promote processing of introns containing weak splicing signals. Here, we extend these studies by showing that also 'strong' constitutively active introns are absolutely dependent on a downstream splicing enhancer for activity in vitro. SR protein binding to exonic enhancer elements or U1 snRNP binding to a downstream 5' splice site serve redundant functions as activators of splicing. We further show that a 5' splice site is most effective as an enhancer of splicing. Thus, a 5' splice site is functional in S100 extracts, under conditions where a SR enhancer is nonfunctional. Also, splice site pairing occurs efficiently in the absence of exonic SR enhancers, emphasizing the significance of a downstream 5' splice site as the enhancer element in vertebrate splicing.

  • 246900. Yue, Lei
    et al.
    Fu, Chaochao
    Feng, Sun
    Qui, Zhi-Jun
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Dongping
    Microwave annealing as a low thermal budget technique for ZnO thin-film transistors fabricated using atomic layer deposition2017In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 38, p. 1390-1393Article in journal (Refereed)
    Abstract [en]

    Microwave annealing (MWA) and furnace annealing are compared for their low thermal budget capability to improve the characteristics of ZnO-based thin-film transistors (TFTs). Both the ZnO channel and the Al2O3 gate dielectric are fabricated using atomic layer deposition. Using Si-wafer-susceptor assisted MWA with a substantial reduction of both annealing temperature and duration, significant improvements of the characteristics of the ZnO TFTs can be attained. A multi-step MWA process is found to further improve the characteristics of the TFTs. For the same microwave power and total duration, the field-effect mobility of the multi-step MWA TFT is 42% greater than that of the one-step MWA TFT with a similar sub-threshold swing. The multi-step MWA process can serve the purpose at temperatures as low as 220 degrees C.

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