检索结果-南通市图书馆

Am.rican Journal of Plant Sciences 2018年第10期9卷 1987-2003页

作者： Ava m. Hoffm.n m.linda D. smith Departm.nt of Biology/Graduate Degree Program.in Ecology Colorado State University Fort Collins USA

Intraspecific diversity has widespread effects on ecological com.unities and ecosystem.. To elucidate the m.chanism. underlying these effects, m.nipulative studies require a rigorous and efficient em.irical approach. Yet, replicating sufficient num.ers of genetically identical individuals rem.ins a challenge. As a result, we are lim.ted in our understanding of the m.chanism. underlying the ecological effects of intraspecific diversity. In contrast, large sam.le sizes are routinely produced in horticultural research using m.cropropagation, or tissue culture. In order to determ.ne the potential usefulness of m.cropropagation technique for ecological studies, we investigated the efficiency and efficacy of m.cropropagation on the ecologically im.ortant non-m.del C4 grass species, Andropogon gerardii. Our prelim.nary results dem.nstrate that m.cropropagation is a rapid and effective technique for producing large num.ers of genetically identical clones at up to 100 tim.s the rate of traditional propagation. Key intraspecific differences am.ng clones of A. gerardii were also retained through the m.cropropagation process. Given that traditional techniques used to test the effects of intraspecific diversity m.nipulations are tim.-lim.ting (greenhouse propagation) or can be biologically m.srepresentative (seeds) for som. species, we suggest that m.cropropagation m.ght be a powerful tool for advancing ecological genetics studies in m.ny plant system..

关键词： Intraspecific Diversity m.cropropagation Perennial Grass Ecology

Changes in Diatom.Biodiversity in Lake Sinclair, Baldwin County, Georgia, USA

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 Water Resource and Protection 2013年第7期5卷 732-742页

作者： m.rká E. smith Kalina m. m.noylov Departm.nt of Biological and Environm.ntal Sciences Georgia College and State University Milledgeville USA

The effects of increased water tem.erature on algal com.unity com.osition were investigated in Lake Sinclair, Baldwin County, Georgia, USA. The lake received waste cooling water from.a coal burning power plant. Discharges of recycled lake water were, on average, 15°C ± 1.5°C (and up to 23°C) warm.r than typical am.ient tem.eratures. Seasonal changes in algal com.osition were observed, and the warm.r sam.le site had a greater diversity of diatom.species year round independent of changes in tem.erature. Therm.l pollution created a high percent dissim.larity between diatom. at the warm.r site and the rem.inder of the lake. Species turnover observed in natural sam.les was not detected for the warm.r site. Anthropogenic therm.l pollution was im.licated as the factor inducing changes in the natural algal com.unity com.osition, which m.y im.act other trophic levels and ultim.tely the overall ecology of Lake Sinclair.

关键词： Diatom. Heated Water Southern Lakes Therm.l Pollution

Raccoon Use of Den Trees and Plant Associations in Western m.sophytic Forests: Tree Attributes and Availability or Landscape Heterogeneity?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Natural Resources 2012年第3期3卷 75-87页

作者： Winston P. smith Keith m. Endres Departm.nt of Biology and Center for m.nagem.nt Utilization and Protection of Water Resources Tennessee Technological University Cookeville USA United States Departm.nt of Agriculture Forest Service Southern Research Station Center for Bottomland Hardwood Research Stoneville USA Institute of Arctic Biology University of Alaska—Fairbanks Fairbanks USA

We m.nitored 15 radio-collared raccoons (Procyon lotor) on Davies Island in m.rch 1987 - m.y 1988 to determ.ne the extent to which individual tree attributes or spatial configuration of plant associations (habitat types) across the landscape influenced den use. Of 1091 verified den sites, 428 were in tree cavities. Raccoon occurrence am.ng 4 cover types differed from.that expected based on the total area of each across the island and varied across all seasons for all habitat types except Cedar Wood. Preference varied am.ng age and sex groups and across seasons with som. groups showing opposite selection for the sam. cover type in different seasons. Species and diam.ter-class distributions of selected den trees differed from.a random.sam.le of trees across the landscape. Species com.osition of trees with cavities also differed from.the species com.osition across the study area. Am.rican beech (Fagus grandifolia—relative abundance 8.7%) was over-represented in the sam.le of trees with cavities (29.4%) and trees selected as dens (65%);diam.ter at breast height (dbh) of beech den trees averaged 80.0 cm. whereas all beech trees averaged 71.2 cm. For all species com.ined, m.an dbh of den trees was 78.4 cm.as com.ared to trees with cavities (67.6 cm., or all trees (50.4 cm.. The relative availability of large, cavity-prone tree species was related to previous logging practices.

关键词： Den Use Habitat Use Landscape Heterogeneity Procyon lotor Resource Availability m.sophytic Forest

The pleiotropic effects of tissue plasm.nogen activator in the brain:im.lications for stroke recovery

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2016年第9期11卷 1401-1402页

作者： Julia A.Grum.isch Nafisa m.Jadavji Patrice D.smith Departm.nt of Neuroscience Carleton University

Tissue plasm.nogen activator （tPA） use in the treatm.nt of isch- em.c stroke： tPA is a serine protease that catalyzes the breakdown of blood dots. Because of its throm.olytic properties, tPA is used to treat specific types of stroke, including ischem.a, but is contra- indicated for treatm.nt of hem.rrhagic stroke or head traum.. Although a life saving and powerful ＇dot buster＇, tPA has a short therapeutic window. When adm.nistered outside of this prescribed tim.fram., research suggests that tPA can produce neurotoxic ef- fects in the brain, due in part to activation of several signalling pro- cesses associated with cell apoptosis, degradation of the extracel- lular m.trix, and increase in the perm.ability of the neurovascular unit （Yepes et al., 2009）. Concerted research has been dedicated to- ward understanding the m.chanism. m.diating the im.act of tPA on the brain, using both in vivo and in vitro anim.l m.dels.

关键词： The pleiotropic effects of tissue plasm.nogen activator in the brain PA

m.delling the daily risk of Ebola in the presence and absence of a potential vaccine

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

Infectious Disease m.delling 2020年第1期5卷 905-917页

作者： Stéphanie m.C.Abo Robert smith Departm.nt of Applied m.them.tics The University of WaterlooWaterlooCanada Departm.nt of m.them.tics and Faculty of m.dicine The University of Ottawa150 Louis-Pasteur PvtOttawaONK1N6N5Canada

Ebola virus d one of the deadliest viral diseases,with a m.rtality rate around 90%d dam.ges the im.une system.and organs,with sym.tom. including episodic fever,chills,m.laise and *** Recom.inant Vesicular Stom.titis Virus-based candidate vaccine(rVSV-ZEBOV)has dem.nstrated clinical efficacy against Ebola in ring-vaccination clinical *** order to evaluate the potential effect of this candidate vaccine,we developed risk equations for the daily risk of Ebola infection both currently and after *** risk equations account for the basic transm.ssion probability of Ebola and the lowered risk due to various protection protocols:vaccination,hazm.t suits,reduced contact with the infected living and dead *** space was sam.led using Latin Hypercube Sam.ling,a statistical m.thod for generating a near-random.sam.le of param.ter *** found that at a high transm.ssion rate of Ebola(i.e.,if the transm.ssion rate is greater than 90%),a large fraction of the population m.st be vaccinated(>80%)to achieve a 50%decrease in the daily risk of *** a vaccine is introduced,it m.st have at least 50%efficacy,and alm.st everyone in the affected areas m.st receive it to effectively control outbreaks of *** results indicate that a low-efficacy Ebola vaccine runs the risk of having vaccinated people be overconfident in a weak vaccine and hence the possibility that the vaccine could m.ke the situation worse,unless the population can be sufficiently educated about the necessity for high vaccine uptake.

关键词： Ebola virus disease m.them.tical m.del Risk equations Latin hypercube sam.ling Eradication

COm.LEXITY OF SYSTEm.m.INTAINABILITY ANALYSIS BASED ON THE INTERPRETIVE STRUCTURAL m.DELING m.THODOLOGY： TRANSDISCIPLINARY APPROACH

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 System. Science and System. Engineering 2016年第2期25卷 254-268页

作者： A. Ertas m.W. smith D. Tate W.D. Lawson T.B. Baturalp Departm.nt of m.chanical Engineering Texas Tech University Lubbock TX USA 79410 Departm.nt of Industrial Design Xi 'an Jiaotong-Liverpool University Suzhou 215123 Jiangsu China Departm.nt of Civil Engineering Texas Tech University Lubbock TX USA 79410

This paper outlines a diagnostic approach to quantify the m.intainability of a Com.ercial off-the-Shelf （COTS）-based system.by analyzing the com.lexity of the deploym.nt of the system.com.onents. Interpretive Structural m.deling （ISm. is used to dem.nstrate how ISm.supports in identifying and understanding interdependencies am.ng COTS com.onents and how they affect the com.lexity of the m.intenance of the COTS Based System.（CBS）. Through ISm.analysis we have determ.ned which com.onents in the CBS contribute m.st significantly to the com.lexity of the system. With the ISm. architects, system.integrators, and system.m.intainers can isolate the COTS products that cause the m.st com.lexity, and therefore cause the m.st effort to m.intain, and take precautions to only change those products when necessary or during m.jor m.intenance efforts. The analysis also clearly shows the com.onents that can be easily replaced or upgraded with very little im.act on the rest of the system.

关键词： COTS Based System m.intainability com.lexity Interpretive Structural m.deling

Resection of isolated liver oligom.tastatic disease in pancreatic ductal adenocarcinom.:Is there a survival benefit?A system.tic review

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 Gastrointestinal Surgery 2023年第7期15卷 1512-1521页

作者： Jam.s m.Halle-smith Sarah Powell-Brett Keith Roberts Nikolaos A Chatzizacharias Departm.nt of HPB and Liver Transplant Queen Elizabeth HospitalUniversity of BirminghamBirmingham B152GWUnited Kingdom

BACKGROUND Presence of liver m.tastatic disease in pancreatic ductal adenocarcinom.(PDAC),either synchronous or m.tachronous after pancreatic resection,is a term.nal diagnosis that warrants m.nagem.nt with palliative intent as per all international practice ***,there is an increasing interest on any potential value of surgical treatm.nt of isolated oligom.tastatic disease in selected *** To present the published evidence on surgical m.nagem.nt of PDAC liver m.tastases,synchronous and m.tachronous,and com.are the outcom.s of these treatm.nts to the current standard of *** A system.tic review was perform.d in line with the Preferred Reporting Item. for System.tic Review and m.ta-Analyses guidelines to com.are the outcom.s of both synchronous and m.tachronous liver m.tastases resection to standard *** 356 studies were identified,31 studies underwent full-text review and of these 10 were suitable for *** synchronous resection of liver m.tastases was com.ared to standard care,m.st studies did not dem.nstrate a survival benefit with the exception of one study that utilised neoadjuvant ***,resection of m.tachronous disease appeared to confer a survival advantage when com.ared to treatm.nt with chem.therapy *** A survival benefit m.y exist in resection of selected cases of m.tachronous liver oligom.tastatic PDAC disease,after disease biology has been tested with tim. and system.c *** survival benefit is less clear in synchronous cases;however an approach with neoadjuvant treatm.nt and consideration of resection in som. selected cases m.y confer som. *** studies should focus on pathways for selection of cases that m.y benefit from.an aggressive approach.

关键词： Pancreas cancer Liver m.tastases Surgical resection System.tic review

The Production of Biofuels in South Africa： Policy and Availability of Energy Crops

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 Environm.ntal Science and Engineering 2010年第2期4卷 70-79页

作者： m. smith N. Kotze C. Cooper Departm.nt of Geography Environmental Management and Energy Studies University of Johannesburg PO Box 524Auckland Park 2006 South Africa

Biofuels could contribute, on a worldwide basis, to the attainm.nt of international energy-policy objectives in three ways： by reducing dependence on im.orted oil; by increasing the availability of renewable energy sources; and by dealing with environm.ntal issues. One such environm.ntal issue is the unsustainable use of agricultural land. There is a need in South Africa there to convert to sustainable and renewable energy resources, such as biofuels, but the production of biofuels will ultim.tely place pressure on the lim.ted and fragile agricultural resources of the country. This paper sets out firstly to investigate national agricultural policies which could im.act on the production of biofuels. It points out that national agricultural policies are ham.ering the dom.stic production of biofuels in that the focus is on land reform.and increasing the volum. of agricultural exports, whereas the provision of food and energy to m.et dom.stic needs features only as a secondary aim. The second objective of this paper is to investigate the possibility of utilising energy crops for biofuel production in South Africa. Annual agricultural production, surplus im.ort and export figures, provide an indication of the capacity of South African farm.rs to produce crops for biofuel production.

关键词： Biofuels energypolicy energy crops resources South Africa

Estim.tes of voluntary activation in individuals with anterior cruciate ligam.nt reconstruction:Effects of type of stim.lator,num.er of stim.li,and quantification technique

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 Sport and Health Science 2022年第1期11卷 85-93页

作者： Steven A.Garcia Kazandra m.Rodriguez Scott R.Brown Riann m.Palm.eri-smith Chandram.uli Krishnan School of Kinesiology University of MichiganAnn ArborMI 48109USA Neurom.scular and Rehabilitation Robotics Laboratory(NeuRRo Lab) Department of Physical Medicine and RehabilitationUniversity of MichiganAnn ArborMI 48108USA Departm.nt of Orthopaedic Surgery Michigan MedicineUniversity of MichiganAnn ArborMI 48109USA Robotics Institute University of MichiganAnn ArborMI 48109USA

Background:Accurate quantification of voluntary activation is im.ortant for understanding the extent of quadriceps dysfunction in individuals with anterior cruciate ligam.nt reconstruction(ACLR).Voluntary activation has been quantified using both percent activation derived from.the interpolated twitch technique and central activation ratio(CAR)derived from.the burst superim.osition technique,as well as by using different types of electrical stim.lators and pulse train ***,it is unclear how these param.ters affect voluntary activation estim.tes in individuals with *** study was perform.d to fill this im.ortant knowledge gap in the anterior cruciate ligam.nt ***:Quadriceps strength and voluntary activation were exam.ned in 18 ACLR participants(12 quadriceps/patellartendon graft,6 ham.tring tendon graft;tim. since ACLR:1.06±0.82 years,m.an±SD)at 90°of knee flexion using 2 stim.lators(Digitim.r and Grass)and pulse train conditions(3-pulse and 10-pulse).Voluntary activation was quantified by calculating both CAR and percent ***:Results indicated that voluntary activation was significantly overestim.ted by CAR when com.ared with percent activation(pm.tes were not affected by pulse train conditions when using percent activation;however,3-pulse stim.li resulted in greater overestim.tion than 10-pulse stim.li when using CAR(p=0.003).Voluntary activation did not differ between stim.lators(p>0.05);however,the Digitim.r evoked greater torque at rest than the Grass(pm.the interpolated twitch technique provides superior estim.tes of voluntary activation than CAR derived from.burst superim.osition and is less affected by pulse train conditions or stim.lators in individuals with ACLR.

关键词： Anterior cruciate ligam.nt Central activation Inhibition Knee strength Triplet Twitch interpolation

Balanced and Unbalanced Com.onents of m.ist Atm.spheric Flows with Phase Changes

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

Chinese Annals of m.them.tics,Series B 2019年第6期40卷 1005-1038页

作者： Alfredo N.WETZEL Leslie m.smith Sam.el N.STECHm.NN Jonathan E.m.RTIN Departm.nt of m.them.tics University of Wisconsin-MadisonMadisonWI 53706USA Departm.nt of m.them.tics and Departm.nt of Engineering Physics University of Wisconsin-MadisonMadisonWI 53706USA Departm.nt of m.them.tics and Departm.nt of Atm.spheric and Oceanic Sciences University of Wisconsin-MadisonMadisonWI 53706USA Departm.nt of Atm.spheric and Oceanic Sciences University of Wisconsin-MadisonMadisonWI 53706USA

Atm.spheric variables(tem.erature, velocity, etc.) are often decom.osed into balanced and unbalanced com.onents that represent low-frequency and high-frequency waves, respectively. Such decom.ositions can be defined, for instance, in term. of eigenm.des of a linear operator. Traditionally these decom.ositions ignore phase changes of water since phase changes create a piecewise-linear operator that differs in different phases(cloudy versus non-cloudy). Here we investigate the following question: How can a balanced–unbalanced decom.osition be perform.d in the presence of phase changes? A m.thod is described here m.tivated by the case of sm.ll Froude and Rossby num.ers,in which case the asym.totic lim.t yields precipitating quasi-geostrophic equations with phase changes. Facilitated by its zero-frequency eigenvalue, the balanced com.onent can be found by potential vorticity(PV) inversion, by solving an elliptic partial differential equation(PDE), which includes Heaviside discontinuities due to phase changes. The m.thod is also com.ared with two sim.ler m.thods: one which neglects phase changes, and one which sim.ly treats the raw pressure data as a stream.unction. Tests are shown for both synthetic, idealized data and data from.Weather Research and Forecasting(WRF) m.del sim.lations. In com.arisons, the phase-change m.thod and no-phase-change m.thod produce substantial differences within cloudy regions, of approxim.tely 5K in potential tem.erature, due to the presence of clouds and phase changes in the data. A theoretical justification is also derived in the form.of a elliptic PDE for the differences in the two stream.unctions.

关键词： Potential vorticity inversion m.ist atm.spheric dynam.cs Slow-fast system. Balanced-unbalanced decom.osition Elliptic partial differential equations