检索结果-南通市图书馆

On combinatorial Gauss-Bonnet Theorem for general Euclidean simplicial complexes

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2016年第5期11卷 1345-1362页

作者： stephan KLAUS Scientific Administrator of the MFO and Adjunct Professor at Mainz University Mathematisches Forschungsinstitut Oberwolfach gGmbH (MFO) Schwarzwaldstrasse 9-11 D-77709 Oberwolfach-Walke Germany

For a finitely triangulated closed surface M2, let αx be the sum of angles at a vertex x. By the well-known combinatorial version of the 2- dimensional Gauss-Bonnet Theorem, it holds ∑x（2π- αx） =2αχ（M^2）, where X denotes the Euler characteristic of M^2, αx denotes the sum of angles at the vertex x, and the sum is over all vertices of the triangulation. We give here an elementary proof of a straightforward higher-dimensional generalization to Euclidean simplicial complexes K without assuming any combinatorial manifold condition. First, we recall some facts on simplicial complexes, the Euler characteristics and its local version at a vertex. Then we define δ（τ） as the normed dihedral angle defect around a simplex τ. Our main result is ∑τ（-1）^dim（τ）δ（τ） = χ（K）, where the sum is over all simplices τ of the triangulation. Then we give a definition of curvature k（x） at a vertex and we prove the vertex-version ∑x∈K0 k（x） = χ（K） of this result. It also possible to prove Morse-type inequalities. Moreover, we can apply this result to combinatorial （n ＋ 1）-manifolds W with boundary B, where we prove that the difference of Euler characteristics is given by the sum of curvatures over the interior of W plus a contribution from the normal curvature along the boundary B： χ（W）- 1/2 χ（B） = ∑τ∈W-B（-1）^dim（τ）δ（τ）＋ ∑τB（-1）^dim（τ）ρ（τ）.

关键词： Curvature dihedral angle Euclidean simplex triangulation Euler characteristic Euler manifold combinatorial manifold pseudo manifold

Hepatitis B virus taxonomy and hepatitis B virus genotypes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第1期13卷 14-21页

作者： stephan Schaefer Abteilung für Virologie Institut für Medizini-sche MikrobiologieVirologie und HygieneUniversitt RostockSchillingallee 70D-18057 RostockGermany

Hepatitis B virus(HBV) is a member of the hepadnavirus *** can be found in both mammals(orthohepadnaviruses) and birds(avihepadnaviruses).The genetic variability of HBV is very *** are eight genotypes of HBV and three clades of HBV isolates from apes that appear to be additional genotypes of *** genotypes are now divided into subgenotypes with distinct virological and epidemiological *** addition,recombination among HBV genotypes increases the variability of *** review summarises current knowledge of the epidemiology of genetic variability in hepadnaviruses and,due to rapid progress in the field,updates several recent reviews on HBV genotypes and subgenotypes.

关键词： Orthohepadnavirus Avihepadnavirus Hepatitis B virus Genotype, Subgenotype Recombination

Scientific guidelines for preclinical research on potentised preparations manufactured according to current pharmacopoeias-the PrePoP guidelines

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Medicine 2024年第5期22卷 533-544页

作者： Alexander L.Tournier Leoni V.Bonamin Susann Buchheim-Schmidt Steven Cartwright Christoph dombrowsky Paul doesburg Carla Holandino Maria Olga Kokornaczyk Everine Bvan de Kraats Jesús Antonio López-Carvallo Papiya Nandy JoséManuel Mazón-Suástegui Fateme Mirzajani Bernard Poitevin Claudia Scherr Karin Thieves Sandra Würtenberger stephan Baumgartner Institute of Complementary and Integrative Medicine University of Bern3010 BernBernSwitzerland Institute of Integrative Medicine Witten/Herdecke University58455 WittenNorth Rhine–WestphaliaGermany Homeopathy Research Institute London SW74EFUnited Kingdom Graduate Program on Environmental and Experimental Pathology Paulista UniversitySão Paulo 01504-000São PauloBrazil department of Medical Science Deutsche Homöopathie-Union DHU-Arzneimittel GmbH&Co.KG76227 KarlsruheBaden-WürttembergGermany Cherwell Laboratory for Fundamental Research in Homeopathy Oxford OX28NUOxforeshireUnited Kingdom Society for Cancer Research Hiscia Research Institute4144 ArlesheimBaselSwitzerland Laboratório Multidisciplinar de Ciências Farmacêuticas Universidade Federal do Rio de JaneiroRio de Janeiro 21941-902Rio de JaneiroBrazil World Water Community Rotterdam 3029AKthe Netherlands departamento de Acuicultura Facultad de Ciencias del MarUniversidad Católica del Norte1790437 CoquimboElquiChile Centre for Interdisciplinary Research and Education KolkataWest Bengal 700068West BengalIndia Laboratorio de Homeopatía Acuícola y Semillas Marinas Centro de Investigaciones Biológicas del NoroesteLa Paz 23096Baja California SurMexico Protein Research Center Shahid Beheshti UniversityTehran ***Iran department of Medical Laboratory Science College of ScienceKnowledge University44001 ErbilErbilIraq SociétéSavante d’Homéopathie 75009 ParisFrance Sola Salus Institute for Homeopathic Research52511 GeilenkirchenNorth Rhine–WestphaliaGermany Scientific Society for Homeopathy 06366 KöthenSaxony-AnhaltGermany

Objective Pharmacopoeias regulate the manufacture of potentised pharmaceutical preparations used in different branches of complementary and integrative *** physicochemical properties and biological activity of these preparations are often investigated in preclinical research,yet no guidelines for experimental research currently exist in this *** present PrePoP guidelines aim to provide recommendations to promote high-quality,statistically sound,and reproducible preclinical research on potentised *** Input was gathered from researchers nominated by the relevant scientific societies using a simplified delphi consensus approach covering the most relevant aspects of basic research methodology in the field including appropriate controls,sample preparation and handling,and *** three rounds of feedback,a consensus was finally reached on the most important aspects and considerations for conducting high-quality research on potentised *** We present a series of recommendations on a range of topics including experimental controls,system stability,blinding and randomisation,environmental influences,and procedures for the preparation of potentised samples and controls,and we address some specific challenges of this research *** This expert consensus process resulted in a robust set of methodological guidelines for research on potentised preparations and provides a valuable framework that will inform and improve the quality of subsequent research in this emerging field.

关键词： Research guidelines Fundamental research Basic research Complementary and integrative medicine Potentisation Potentised preparations

Horn–Schunck optical flow applied to deformation measurement of a birdlike airfoil

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第5期28卷 1305-1315页

作者： Gong Xiaoliang stephan Bansmer School of Aeronautics Northwestern Polytechnical University Institute of Fluid Mechanics Technische Universitt Braunschweig

Current deformation measurement techniques suffer from limited spatial resolution. In this work, a highly accurate and high-resolution Horn Schunck optical flow method is developed and then applied to measuring the static deformation of a birdlike flexible airfoil at a series of angles of attack at Reynolds number 100,000 in a low speed, low noise wind tunnel. To allow relatively large displacements, a nonlinear Horn-Schunck model and a coarse-to-fine warping process are adopted. To preserve optical flow discontinuities, a nonquadratic penalization function, a multi- cue driven bilateral filtering and a principle component analysis of local image patterns are used. First, the accuracy and convergence of this Horn-Schunck technique are verified on a benchmark. Then, the maximum displacement that can be reliably calculated by this technique is studied on synthetic images. Both studies are compared with the performance of a Lucas-Kanade optical flow method. Finally, the Horn-Schunck technique is used to estimate the 3-d deformation of the birdlike airfoil through a stereoscopic camera setup. The results are compared with those computed by Lucas-Kanade optical flow, image correlation and numerical simulation.

关键词： deformation measurementsFlexible airfoil Horn-Schunck Optical flow Stereoscopic

Heteronuclear Efimov resonances in ultracold quantum gases

在线全文

学校读者我要写书评

暂无评论

National Science Review 2016年第2期3卷 174-188页

作者： Juris Ulmanis stephan Hfner Eva d.Kuhnle Matthias Weidemller Physikalisches Institut Universitt Heidelberg Hefei National Laboratory for Physical Sciences at the Microscale and department of Modern Physics and CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum PhysicsUniversity of Science and Technology of China

The Efimov scenario is a universal three-body effect addressing many areas of modern quantum *** plays an important role in the transition between few- and many-body physics and has enabled important breakthroughs in the understanding of the universal few-body *** review the basic concepts of the Efimov scenario with specific emphasis on the similarities and differences between homonuclear and heteronuclear *** the latter scenario,the existence of a second,independently tunable interaction parameter enables novel few-body phenomena that are universal and have no counterexamples in the homonuclear *** discuss recent experimental approaches using ultracold atomic gases with magnetically tunable interactions and elucidate the role of short-range interactions in the emergence of universal and non-universal behavior.

关键词： Efimov resonances few-body physics Feshbach resonances ultracold atoms resonant scattering

Proterozoic tectonothermal processes imaged with magnetotellurics and seismic reflection in southern Australia

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2020年第3期11卷 885-893页

作者： Tom Wise stephan Thiel Geological Survey of South Australia Department for Energy and MiningAdelaideSA5005Australia School of Earth and Environmental Sciences University of AdelaideAdelaideSA5005Australia

Over the last two decades,co-located seismic and magnetotelluric(MT) profiles provided fundamental geophysical data sets to image the Australian *** their complimentary nature,the data are processed and often interpreted separately without common processes in *** here qualitatively compare 2 d resistivity inversion models derived from MT and seismic reflection profiles across a region of Archean-Proterozoic Australia to address the causes of variations in seismic response and anomalous conductivity in the *** find that there exists a spatial association between regions of low reflectivity in seismic sections and low resistivity in co-located2 d MT modelled *** relationships elucidate possible signatures of past magmatic and fluid-related *** on their diffuse or discrete character,we hypothesize these signatures signify fossil melting of the crust due to mafic underplating,magma movement or hydrothermal fluid flow through the *** approach discussed herein is a process-oriented approach to interpretation of geophysical images and a significant extension to traditional geophysical methods which are primarily sensitive to a singular bulk rock property or state.

关键词： Magnetotellurics Seismic reflection Resistivity

Viral and cellular determinants involved in hepadnaviral entry

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第1期13卷 22-38页

作者： dieter Glebe stephan Urban Institute of Medical Virology Justus-Liebig University of Giessen Frankfurter Str. 107 D-35392 Giessen Germany department of Molecular Virology Otto Meyerhof Zentrum University of Heidelberg Im Neuenheimer Feld 350 D-69120 Heidelberg Germany

Hepadnaviridae is a family of hepatotropic dNA viruses that is divided into the genera orthohepadnavirus of mammals and avihepadnavirus of birds. All members of this family can cause acute and chronic hepatic infection, which in the case of human hepatitis B virus （HBV） constitutes a major global health problem. Although our knowledge about the molecular biology of these highly liver-specific viruses has profoundly increased in the last two decades, the mechanisms of attachment and productive entrance into the differentiated host hepatocytes are still enigmatic. The difficulties in studying hepadnaviral entry were primarily caused by the lack of easily accessible in vitro infection systems. Thus, for more than twenty years, differentiated primary hepatocytes from the respective species were the only in vitro models for both orthohepadnaviruses （e.g. HBV） and avihepadnaviruses （e.g. duck hepatitis B virus [dHBV]）. Two important discoveries have been made recently regarding HBV：（1） primary hepatoo/tes from tree-shrews; i.e., Tupaia belangeri, can be substituted for primary human hepatocytes, and （2） a human hepatoma cell line （HepaRG） was established that gains susceptibility for HBV infection upon induction of differentiation in vitro. A number of potential HBV receptor candidates have been described in the past, but none of them have been confirmed to function as a receptor. For dHBV and probably all other avian hepadnaviruses, carboxypeptidase d （CPd） has been shown to be indispensable for infection, although the exact role of this molecule is still under debate. While still restricted to the use of primary duck hepatocytes （PdH）, investigations performed with dHBV provided important general concepts on the first steps of hepadnaviral infection. However, with emerging data obtained from the new HBV infection systems, the hope that dHBV utilizes the same mechanism as HBV only partially held true. Nevertheless, both HBV and dHBV in vitro infection systems will help

关键词： Hepatitis B virus duck hepatitis B virus Infection models Receptor Viral attachment Tupaia belangeri HepaRG Carboxypeptidase d

From foredeep to orogenic wedge-top: The Cretaceous Songliao retroforeland basin, China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2023年第3期14卷 65-73页

作者： Zhiqiang Feng stephan A.Graham Petroleum Exploration and Production Research Institute SINOPECNo.197 Baisha Rd.Beijing 112206China department of Geological Sciences Stanford UniversityStanfordCA 94305USA

Songliao Basin,the largest Mesozoic intracontinental nonmarine basin in eastern China,initiated during the latest Jurassic as a backarc extensional basin;rifting failed and thermal cooling controlled subsidence through the early Late *** 2-d and 3d reflection seismic and borehole data with regional geological studies,we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma(marked by the T11 unconformity in the basin),including(1)significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin;(2)a shift of detrital provenance in the basin from north to southeast;and(3)propagation of E-W shortened structures,increasing eastward in amplitude,frequency,and degree of inversion toward the *** latest Cretaceous,foreland basin fill progressively deformed,as the foredeep evolved to a wedge-top tectonic setting,marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 *** of the basin was brought into the orogenic wedge and eroded by the end of the *** Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the *** normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin,whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the *** foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma.

关键词： Retroforeland basin Intracontinental basin Seismic reflection and borehole data Lithospheric plate dynamics Songliao basin

Euler-Lagrange/dEM simulation of wood gasification in a bubbling fluidized bed reactor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2009年第4期7卷 307-316页

作者： Michael Oevermann stephan Gerber Frank Behrendt Berlin Institute of Technology School of Process Sciences and EngineeringDepartment of Energy Engineering Fasanenstr.8910623 BerlinGermany

We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2d Navier-Stokes equations and the solid phase is modeled by a discrete Element Method （dEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.

关键词： Euler-Lagrange simulation discrete element method (dEM) dense fluidized bed Biomass gasification