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A geometric interpretation of the transition density of a symmetric Lévy process

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Science China Mathematics 2012年第6期55卷 1099-1126页

作者： JACOB Niels KNOPOVA Victorya LANDWEHR sandra SCHILLING RenéL. Department of Mathematics Swansea UniversitySingleton ParkSwansea SA28PPUK V.M.Glushkov Institute of Cybernetics NAS of Ukraine 03187KievUkraine Heinrich Heine University Düsseldorf German Diabetes Center at the Heinrich Heine University DüsseldorfLeibniz Center for Diabetes ResearchInstitute of Biometrics and EpidemiologyAuf'm Hennekamp 6540225 DüsseldorfGermany Institut für Mathematische Stochastik Technische Universität Dresden01062 DresdenGermany

We study for a class of symmetric Levy processes with state space R^n the transition density pt（x） in terms of two one-parameter families of metrics, （dt）t〉o and （δt）t〉o. The first family of metrics describes the diagonal term pt （0）; it is induced by the characteristic exponent ψ of the Levy process by dr（x, y） = √tψ（x - y）. The second and new family of metrics 6t relates to √tψ through the formula exp（-δ^2t（x,y））=F[e^-tψ/pt（0）]（x-y）,where Y denotes the Fourier transform. Thus we obtain the following ＂Gaussian＂ representation of the tran- sition density： pt（x） = pt（O）e^-δ^2t（x,0） where pt（O） corresponds to a volume term related to √tψ and where an ＂exponential＂ decay is governed by 5t2. This gives a complete and new geometric, intrinsic interpretation of pt（x）.

关键词： transition function estimates Levy processes metric measure spaces heat kernel bounds in-finitely divisible distributions self-reciprocal distributions

Marginal zone B cells are naturally reactive to collagen type II and are involved in the initiation of the immune response in collagen-induced arthritis

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Cellular & Molecular Immunology 2011年第4期8卷 296-304页

作者： Cecilia Carnrot Kajsa E Prokopec Kristina Rasbo Mikael CI Karlsson sandra Kleinau Department of Cell and Molecular Biology Uppsala UniversityUppsalaSweden Department of Medicine Unit of Clinical Allergy ResearchThe Karolinska InstituteSolnaSweden

Antibodies against type II collagen(CII)are essential for development of collagen-induced arthritis(CIA),but how and where the B-cell response to CII is initiated is not fully *** show here that naive DBA/1 mice display naturally reactive IgM and IgG anti-CII producing B cells prior to *** CII-reactive B cells were observed in the spleen and recognized as marginal zone(MZ)B *** CII immunization,CII-specific B cells expanded rapidly in the spleen,in contrast to the lymph nodes,with the initial response derived from MZ B cells and later by follicular(FO)B *** was evident despite that the MZ B cells were subject to stringent tolerance mechanisms by having a greater Fc gamma receptor IIb expression than the FO B ***,the MZ B cells migrated to the FO areas upon immunization,possibly providing antigen and activating FO T cells and subsequently FO B ***,around CIA onset increased numbers of IgG anti-CII producing FO B cells was seen in the spleen,which was dominated by IgG2a-and IgG2b-positive *** data demonstrate that CII-reactive MZ B cells are present before and expand after CII immunization,suggesting an initiating role of MZ B cells in the development of CIA.

关键词： arthritis B cells collagen type II elISpot marginal zone mice

UDP-glucuronosyltransferases mediate coffee-associated reduction of liver fibrosis in bile duct ligated humanized transgenic UGT1A mice

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Hepatobiliary Surgery and Nutrition 2021年第6期10卷 766-781页

作者： Steffen Landerer sandra Kalthoff Christian P.Strassburg Department of Internal Medicine I University Hospital BonnVenusberg-Campus 1BonnGermany

Background:Coffee consumption has been shown to reduce the risk of liver fibrosis and is capable of inducing human UDP-glucuronosyltransferase(UGT)1A ***1A enzymes act as indirect antioxidants catalyzing the elimination of reactive metabolites,which in turn are potent initiators of profibrotic *** aim of this study was to analyze the role of UGT1A genes as effectors of the protective properties of coffee in bile duct ligation(BDL)induced liver ***:Fourteen days BDL with and without coffee pre-and co-treatment was performed in htgUGT1A-WT and htgUGT1A-SNP *** UGT1A mRNA expression levels,serum bilirubin and aminotransferase activities were *** fibrosis was assessed by collagen deposition,computational analysis of Sirius red tissue staining and expression of profibrotic marker *** stress was measured by hepatic peroxidase concentrations and immunofluorescence ***:UGT1A transcription was differentially activated in the livers of htgUGT1A-WT mice after BDL,in contrast to a reduced or absent induction in the presence of ***-treated(coffee+BDL)htgUGT1A-WT-mice showed significantly increased UGT1A expression and protein levels and a considerably higher induction compared to water drinking WT mice(BDL),whereas in co-treated htgUGT1A-SNP mice absolute expression levels remained below those observed in htgUGT1A-WT *** deposition,oxidative stress and the expression of profibrotic markers inversely correlated with UGT1A expression levels in htgUGT1A-WT and SNP mice after BDL and coffee+BDL ***:Coffee exerts hepatoprotective and antioxidative effects via activation of UGT1A *** hepatic fibrosis as a result of coffee-mediated UGT1A induction during cholestasis was detected,while the protective action of coffee was lower in a common low-function UGT1A SNP haplotype present in 10%of the Caucasian *** study suggests that coffee consumption might

关键词： Glucuronidation cholestasis liver fibrosis coffee oxidative stress

Reproductive biology of largehead hairtail(Trichiurus lepturus)in south-eastern Australia

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Aquaculture and Fisheries 2023年第2期8卷 148-158页

作者： Chantelle Clain John Stewart Ashley Fowler sandra Diamond School of Science Western Sydney UniversityLocked Bag 1797PenrithNSW2751Australia NSW Department of Primary Industries Sydney Institute of Marine ScienceChowder Bay RoadMosmanNSW2088Australia

Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable *** investigated the life-history traits of Trichiurus lepturus(largehead hairtail)in south-eastern Australia;a region of low exploitation for this otherwise heavily exploited circumglobal species,to investigate whether there were differences in the reproductive biology and life-history traits in the south-east Australian population compared with those in other *** also used histological sections to examine male and female gonads at a microscopic *** lepturus in south-eastern Australia had a greater maximum length(193 cm total length(TL)),matured at a larger length(108 cm TL at 50%mature)and had a spawning period(March to September,Austral winter)that was inconsistent with other *** overall sex ratio of 1:0.4 females:males was consistent with a female dominant sex ratio observed in other regions,particularly in larger length ***,females in the current study dominated samples from both estuarine and coastal habitats,as well as during the spawning and non-spawning periods,which is not consistent with the patterns found in other *** in south-eastern Australia may relate to limited fishing pressure,genetic variation,or differences in environmental factors that influence reproductive development,including temperature,trophic resources and habitat.

关键词： Fisheries Length at maturity Histology Spawning period Sex ratio Trichiurus

Recent Advances in Single-Cell Metabolomics Based on Mass Spectrometry

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CCS Chemistry 2023年第2期5卷 310-324页

作者： Qinlei Liu sandra Martínez-Jarquín Renato Zenobi Department of Chemistry and Applied Biosciences ETH ZurichCH-8093 Zurich

Cellular heterogeneity is essential for the physiological functions of organisms,and precise interpretation of the relevant biological mechanisms involved requires accurate measurement of biomolecules,including DNA,RNA,proteins,and metabolites at the single-cell *** metabolites react most rapidly to environmental and biochemical changes such that their detection is a critical step in determining the physiological state of ***,their limited amounts,structural diversity,and significant content variation render single-cell metabolomics analysis technically *** spectrometry,with its high sensitivity,good selectivity,and wide dynamic range,has been widely used in the single-cell analysis in recent *** terms of ionization techniques,there are four main types of single-cell mass spectrometry methods:nano-electrospray ionization mass spectrometry,matrix-assisted laser desorption/ionization mass spectrometry,secondary ion mass spectrometry,and dielectric barrier discharge ionization mass *** this mini review,the progress of single-cellmass spectrometrymethodologies and data processing strategies are summarized,and the future trends in single-cell mass spectrometry are outlined.

关键词： single-cell analysis metabolomics mass spectrometry ionization techniques analytical methods

Anime fan communities

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Anime fan communities

Spatiotemporal patterns of burned areas,fire drivers,and fire probability across the equatorial Andes

作者： (1982-)Annett sandra

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Journal of Mountain Science 2021年第4期18卷 952-972页

作者： Xavier ZAPATA-RiOS Carmen LOPEZ-FABARA Abigail NAVARRETE sandra TORRES-PAGUAY Miguel FLORES Department of Civil and Environmental Engineering Escuela Politecnica NacionalLadron de Guevara E11-253P.O.Box 17-01-2759QuitoEcuador Center for Research and Water Resources Studies(CIERHI) Escuela Politecnica NacionalLadron de Guevara E11-253P.O.Box 17-01-2759QuitoEcuador Faculty of Agricultural Sciences Universidad Central del EcuadorAv.UniversitariaP.O.Box 17-03-100QuitoEcuador Modeling Optimization and Inferential Statistics Group(MODES)Department of MathematicsEscuela Politecnica NacionalLadron de Guevara Ell-253P.O.Box 17-01-2759QuitoEcuador

Field-based fire studies in the equatorial Andes indicate that fires are strongly associated with biophysical and anthropogenic ***,fire controls and fire regimes at the regional scale remain ***,this paper describes spatial and temporal burned-area patterns,identifies biophysical and anthropogenic fire drivers,and quantifies fire probability across 6°of latitude and 3°of longitude in the equatorial *** spatial and temporal burned-area analysis was carried out based on 18 years(2001-2018)of the MCD64 A1 MODIS burned-area ***,topography,vegetation,and anthropogenic variables were integrated in a logistic regression model to identify the significance of explanatory variables and determine fire occurrence probability.A total of 5779 fire events were registered during the 18 years of this study,located primarily along the western cordillera of the Andes and spreading from North to ***-eight percent of these fires took place within two fire hotspots located in the northwestern and southwestern corners of the study ***-nine percent occurred during the second part of the year,between June and *** largest density of fires was primarily located on herbaceous vegetation and *** show that mean monthly temperature,precipitation and NDVI during the prefire season,the location of land cover classes such as forest and agriculture,distance to roads and urban areas,slope,and aspect were the most important determinants of spatial and temporal fire *** logistic regression model achieved a good accuracy in predicting fire probability(80%).Probability was higher in the southwestern and northern corners of the study area,and lower towards the north in the western and eastern piedmonts of the *** analysis contributes to the understanding of fires in mountains within the *** results here presented have the potential to contribute to fire management and control in the regi

关键词： MODIS MCD64A1 Spectral vegetation indices Pre-fire season NDVI and precipitation Remote sensing

An overview of the phylogeny and diversity of eukaryotes

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植物分类学报 2008年第3期46卷 263-273页

作者： sandra L. BALDAUF Department of Evolution Genomics and Systematics Evolutionary Biology Centre University of Uppsala Norbyvaigen 18 D Uppsala 75236 Sweden

Our understanding of eukaryote biology is dominated by the study of land plants, animals and fungi. However, these are only three isolated fragments of the full diversity of extant eukaryotes. The majority of eu-karyotes, in terms of major taxa and probably also sheer numbers of cells, consists of exclusively or predomi-nantly unicellular lineages. A surprising number of these lineages are poorly characterized. Nonetheless, they are fundamental to our understanding of eukaryote biology and the underlying forces that shaped it. This article consists of an overview of the current state of our understanding of the eukaryote tree. This includes the identity of the major groups of eukaryotes, some of their important, defining or simply interesting features and the pro-posed relationships of these groups to each other.

关键词：真核生物多样性系统演化真菌

Experimental reconstructions of 3D atomic structures from electron microscopy images using a Bayesian genetic algorithm

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npj Computational Materials 2022年第1期8卷 2076-2083页

作者： Annick De Backer sandra Van Aert Christel Faes Ece Arslan Irmak Peter DNellist Lewys Jones EMAT University of AntwerpGroenenborgerlaan 1712020AntwerpBelgium NANOlab Center of Excellence University of AntwerpGroenenborgerlaan 1712020AntwerpBelgium I-BioStat Data Science InstituteHasselt UniversityHasseltBelgium Department of Materials University of OxfordParks RoadOX13PHOxfordUK Advanced Microscopy Laboratory Centre for Research on Adaptive Nanostructures and Nanodevices(CRANN)Dublin 2Ireland School of Physics Trinity College DublinThe University of DublinDublin 2Ireland

We introduce a Bayesian genetic algorithm for reconstructing atomic models of monotype crystalline nanoparticles from a single projection using Z-contrast *** number of atoms in a projected atomic column obtained from annular dark field scanning transmission electron microscopy images serves as an input for the initial three-dimensional *** algorithm minimizes the energy of the structure while utilizing a priori information about the finite precision of the atom-counting results and neighbor-mass *** results show promising prospects for obtaining reliable reconstructions of beam-sensitive nanoparticles during dynamical processes from images acquired with sufficiently low incident electron doses.

关键词： algorithm atomic utilizing