检索结果-南通市图书馆

Insect Science 2011年第2期18卷 175-180页

作者： Craig T. Symes stephan woodborne School of Animal Plant and Environmental Sciences University of the Witwatersrand Wits Natural Resources and the Environment CSIR Pretoria South Africa

The diet of the harvester termite Hodotermes mossambicus was investigated at two sites with distinct dietary components： C4 grasses （δ13 C isotope values, -13.8%0 to -14.0%0） and C3 plants （δ13C isotope values, -25.6%0 to -27.1%0）. By comparing observations of food items carried into the colony by the termites and carbon isotope ratios of whole termites （that determined assimilated carbon）, the relative proportion of the C3 and C4 plant food components of the termite diet was estimated. There was agreement between the observational data and stable carbon isotopic data, with grass representing approximately 93% of the diet ofH. mossambicus at two study sites （urban and rural） on the South African highveld. However, when correcting for mass of food items, that is, C3 and C4, carried by termites, the proportion of grass （C4） in the diet may be underestimated.

关键词： carbon assimilation colony harvester termite Suikerbosrand

Stable isotope analysis of diet confirms niche separation of two sympatric species of Namib Desert lizard

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Integrative Zoology 2016年第1期11卷 60-75页

作者： Ian W.MURRAY Hilary M.LEASE Robyn S.HETEM Duncan MITCHELL Andrea FULLER stephan woodborne Brain Function Research Group School of PhysiologyFaculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa Biology Department Whitman CollegeWalla WallaWashingtonUSA iThemba Laboratories GautengSouth Africa Stable Isotope Laboratory Mammal Research InstituteDepartment of Zoology and EntomologyUniversity of PretoriaPretoriaSouth Africa

We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards,the Husab sand lizard Pedioplanis husabensis and Bradfield’s Namib day gecko living sympatrically in the Namib *** measured theδ13C andδ15N ratios in lizard blood tissues with different turnover times(whole blood,red blood cells and plasma)to investigate lizard diet in different *** also measured theδ13C andδ15N ratios in available arthropod prey and plant tissues on the site,to identify the avenues of nutrient movement between lizards and their *** the use of stable isotope mixing models,we found that the two lizard species relied on a largely non-overlapping but seasonally variable array of arthropods:*** primarily fed on termites,beetles and wasps,while *** fed mainly on ants,wasps and *** originating from C3 plants were proportionally higher for *** than for *** during autumn and late autumn/early winter,although not *** to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C3 and C4/crassulacean acid metabolism(CAM)plant landscapes,we found that our lizard species primarily acquired nutrients that originated from C4/CAM *** work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.

关键词： Namib Desert niche partitioning Pedioplanis Rhoptropus stable isotopes

(Not) an elementary question:How to mobilize the iron in the wall?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2021年第10期14卷 1610-1611页

作者： stephan Clemens Department of Plant Physiology and Faculty of Life Sciences:Food Nutrition and HealthUniversity of BayreuthUniversitätsstrasse 3095440 BayreuthGermany

Photosynthesis,respiration,and countless other processes are dependent on proteins that carry iron(Fe)as an essential *** Fe was recruited for biological functions early in evolution,it was an available *** Earth's at... 详细信息

关键词： element. elementary sulfide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Roots dOdge streSs

Molecular Plant 2023年第12期16卷 1885-1886页

作者： stephan Clemens Department of Plant Physiology University of BayreuthUniversitatsstrasse 3095440BayreuthGermany

A hallmark of plant development is *** system architecture modulation in response to fluctuations of nutrient and water supply is a case in point(Giehl et al.,2014).The formation and length of lateral roots or the density of root hairs are strongly influenced by the availability of macro-and *** actively forage for mineral-rich patches in the typically heterogeneous soil environment and adjust their development systemically to increase the surface for nutrient ***,the opposite can happen as well.A recent study by Wang et al.(2023)convincingly demonstrated an active avoidance of unfavorable conditions by rice *** the seminal root of rice seedlings was placed between two agar blocks,one of them containing cations at toxic concentrations,adventitious roots developed only on the non-stress side,while development on the stress side was arrested(Figure 1).Besides,far more lateral roots were formed than in the absence of asymmetrically applied *** a while,this resulted in a total root biomass equivalent to that of control *** roots,in other words,had successfully shifted away from the stressful environment.

关键词： soil roots Figure

On combinatorial Gauss-Bonnet Theorem for general Euclidean simplicial complexes

在线全文

维普期刊数据库

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

A two dimensional Euler-Lagrangian model of wood gasification in a charcoal bed-Part II： Parameter influence and comparison

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 2017年第6期15卷 22-30页

作者： stephan Gerber Michael Oevermann Freie Universitat Berlin Arnimallee 6 14195 Berlin Germany Chalmers University of Technology Department of Applied Mechanics Division of Combustion Gothenburg Sweden

A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle-particle and particle-wall colli- sions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study （Gerber ＆ Oevermann, 2014）. The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with differ- ent sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle-particle and particle-wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reac- tor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.

关键词： Wood gasification simulation Gas-solid flow Discrete element method Pyrolysis Gasification Charcoal

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

在线全文

维普期刊数据库

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

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

维普期刊数据库

同方期刊数据库评论

在线全文

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

Future impact of integrated high-throughput methylome analyses on human health and disease

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2008年第7期35卷 391-401页

作者： Lee M Butcher stephan Beck UCL Cancer Institute Paul O'Gorman Building University College London 72 Huntley Street London WC1E 6BT UK

A spate of high-powered genome-wide association studies （GWAS） have recently identified numerous single-nucleotide polymorphisms （SNPs） robustly linked with complex disease. Despite interrogating the majority of common human variation, these SNPs only account for a small proportion of the phenotypic variance, which suggests genetic factors are acting in concert with non-genetic factors. Although environmental measures are logical covariants for genotype-phenotype investigations, another non-genetic intermediary exists： epigenetics. Epigenetics is the analysis of somatically-acquired and, in some cases, transgenerationally inherited epigenetic modifications that regulate gene expression, and offers to bridge the gap between genetics and environment to understand phenotype. The most widely studied epigenetic mark is DNA methylation. Aberrant methylation at gene promoters is strongly implicated in disease etiology, most notably cancer. This review will highlight the importance of DNA methylation as an epigenetic regulator, outline techniques to characterize the DNA methylome and present the idea of reverse phenotyping, where multiple layers of analysis are integrated at the individual level to create personalized digital phenotypes and, at a phenotype level, to identify novel molecular signatures of disease.

关键词： DNA methylation reverse phenotyping complex disease