检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

有向图上的一些猜想和开放问题

数学进展 2024年第1期53卷 1-12页

作者：艾江东 gregory GUTIN 史永堂 Ander YEO 南开大学数学科学学院核心数学与组合数学教育部重点实验室天津300371 伦敦大学皇家霍洛威学院计算机科学系英国萨里郡TW200EX 南开大学组合数学中心核心数学与组合数学教育部重点实验室天津300371 南丹麦大学数学与计算机科学系丹麦欧登塞M区DK-5230 约翰内斯堡大学数学与应用数学系南非约翰内斯堡2006

讨论了有向图上的几个猜想和开放问题.一些尚未解决的问题是新的.

关键词：有向图出度圈路分划最大有向割集拟核 Seym.ur二次邻域猜想无圈2-染色

The enduring link between forest cover and rainfall： a historical perspective on science and policy discussions

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystem. 2018年第1期5卷 53-61页

作者： Brett m. Bennett gregory A. Barton School of Hum.nities and Com.unication Arts Western Sydney UniversityLocked Bag 1797PenrithNSW 2751Australia Departm.nt of Historical Studies Faculty of HumanitiesUniversity of JohannesburgC-Ring 2-Orange Block(Kingsway Campus)Corner Kingsway and University RoadAuckland ParkSouth Africa

Background： This article traces the history of scientific ideas connecting forest cover with rainfall to inform.ongoing debates about whether forests are net users or producers of water in the hydrological cycle. Scholars of the supply-side school argue that forests are net producers and m.gnifiers that increase rainfall at regional scales. Supply-side scholars seek to challenge the dom.nance of dem.nd-side thinking. The dem.nd-side school em.hasizes that trees are net users of water within a catchm.nt that decrease overall water available for other users. This scientific debate has significant im.lications for the developm.nt of policies to m.nage forests and water. Results： Scientists have debated the question of whether forests im.rove or worsen water balance for over two hundred years. Connections between forests and rainfall gained prom.nence in scientific circles during the second half of the nineteenth century and again during the past three decades. The popularity of forest- rainfall connections has paralleled societal and scientific interest in anthropogenic clim.te change and deforestation. Theories connecting forests with rainfall peaked in popularity in the 1850s to 1880s, a period when scientists expressed alarm.that deforestation caused regional declines in precipitation. Forests were understood to create rain within a locality and region. Scientific consensus shifted by the early twentieth century to the view that forests did not play a significant role in determ.ning rainfall. The forest-rainfall connection reem.rged in the 1980s alongside advances in clim.te m.delling and growing fears of anthropogenic global warm.ng and tropical deforestation. Using new data and theories, supply-side advocates have once again placed a strong forest-rainfall connection into scientific prom.nence. Conclusion： Supply-side m.nagem.nt policies have a checkered history that should elicit caution, while dem.nd-side policies, which are based on alm.st a century of hydrolog

关键词： Clim.te change Environm.ntal history Forests Hydrology Rain Water

Oncogene interactions are required for gliom. developm.nt and progression as revealed by a tissue specific transgenic m.use m.del

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Cancer 2011年第3期30卷 163-172页

作者： Lynette m. m.ore Kristen m. Holm.s gregory N. Fuller Departm.nt of Pathology the University of Texas M. D. Anderson Cancer Center

The aggressive and invasive nature of brain tum.rs has ham.ered progress in the design and im.lem.ntation of efficacious therapies. The recent success of targeted therapies in other tum.r types m.kes this an attractive area for research yet com.licating m.tters is the ability of brain tum.rs to circum.ent the targeted pathways to develop drug resistance. Effective therapies will likely need to target m.re than one signaling pathway or target m.ltiple nodes within a given pathway. Key to identifying these targets is the elucidation of the driver and passenger m.lecules within these pathways. Anim.l m.dels provide a useful tool with m.ny advantages in the study of these pathways. These m.dels provide a m.ans to dissect the critical com.onents of tum.rigenesis, as well as serve as agents for preclinical testing. This review focuses on the use of the RCAS/tv-a m.use m.del of brain tum.rs and describes their unique ability to provide insight into the role of oncogene cooperation in tum.r developm.nt and progression.

关键词：转基因小鼠模型癌基因组织特异性神经胶质瘤相互作用靶向治疗脑肿瘤信号通路

Altered physiology of gastrointestinal vagal afferents following neurotraum.

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2021年第2期16卷 254-263页

作者： Em.ly N.Blanke gregory m.Holm.s Em.ly m.Besecker Departm.nt of Health Sciences Gettysburg CollegeGettysburgPAUSA Departm.nt of Neural and Behavioral Sciences Penn State University College of MedicineHersheyPAUSA

The adaptability of the central nervous system.has been revealed in several m.del *** particular interest to central nervous system.injured individuals is the ability for neural com.onents to be m.dified for regain of *** both types of neurotraum.,traum.tic brain injury and spinal cord injury,the prim.ry parasym.athetic control to the gastrointestinal tract,the vagus nerve,rem.ins anatom.cally ***,individuals with traum.tic brain injury or spinal cord injury are highly susceptible to gastrointestinal *** gastrointestinal dysfunctions attribute to higher m.rbidity and m.rtality following traum.tic brain injury and spinal cord *** the vagal efferent output rem.ins capable of eliciting m.tor responses following injury,evidence suggests im.airm.nt of the vagal *** sensory input drives m.tor output,this review will discuss the norm.l and altered anatom. and physiology of the gastrointestinal vagal afferents to better understand the contributions of vagal afferent plasticity following neurotraum..

关键词： gastrointestinal functions m.crobiom. neurotraum. nodose ganglia sensory neuropathy spinal cord injury traum.tic brain injury vagal afferents visceral reflexes

室温和深冷轧制对纯Al再结晶{111}/{111}近奇异晶界的影响

在线全文

学校读者我要写书评

暂无评论

金属学报 2024年

作者：李振想王卫国 gregory S Rohrer 洪丽华陈松林燕周邦新福建理工大学材料科学与工程学院福建理工大学晶界工程研究所上海大学材料研究所 Departm.nt of m.terial Science and Engineering Carnegie Mellon University

{111}/{111}近奇异晶界比一般晶界更耐蚀，研究此类晶界的形成条件、影响因素和生成机制，设法调控此类晶界并提高其比例是改善相关铝合金晶界腐蚀性能的根本途径。为了解铝合金生成{111}/{111}近奇异晶界的本征行为，本工作选择高纯Al ... 详细信息

{111}/{111}近奇异晶界比一般晶界更耐蚀，研究此类晶界的形成条件、影响因素和生成机制，设法调控此类晶界并提高其比例是改善相关铝合金晶界腐蚀性能的根本途径。为了解铝合金生成{111}/{111}近奇异晶界的本征行为，本工作选择高纯Al (99.99%)为实验材料，首先经室温反复多向锻造和370℃再结晶退火获得晶粒尺寸均匀、平均晶粒尺寸约为20μm.晶粒取向随机分布的组织均匀化初始样品；再将初始样品分别在室温(25℃)和-196℃深冷进行厚度减缩量为80%的轧制变形，及370℃、30 m.n再结晶退火处理。采用EBSD和基于五参数分析的晶界界面匹配定量表征方法对两样品进行测试和分析。结果表明，经-196℃深冷轧制并再结晶的样品，其{111}/{111}近奇异晶界比例达到6.0%，相比室温轧制并再结晶的样品提升了120%。XRD、EBSD及硬度结果表明，经室温和-196℃深冷轧制的样品中均形成了较强的{011}形变织构；较比室温轧制，经-196℃深冷轧制的样品内残余压应力更大，晶粒碎化更严重、储能更高。在后续370℃退火过程中，经室温和-196℃深冷轧制的样品，其再结晶机制均以{011}取向生长为主；较比于室温轧制，经-196℃深冷轧制的样品可提供更大的晶界迁移驱动力，其样品再结晶组织的平均晶粒尺寸更大且{011}再结晶织构更强。统计结果表明，{011}取向晶粒与其他取向的晶粒毗连所形成的晶界中存在较高比例的{111}/{111}近奇异晶界；同时，为{011}取向晶粒与其相邻的且具有{011}漫散取向的晶粒间也形成较多的{111}/{111}近奇异晶界，这是导致经-196℃深冷轧制及再结晶的样品中{111}/{111}近奇异晶界比例较高的主要原因。

关键词：高纯Al 深冷轧制近奇异晶界晶界界面匹配择尤取向

Natural Variation in Tom.to Reveals Differences in the Recognition of AvrPto and AvrPtoB Effectors from.Pseudom.nas syringae

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

m.lecular Plant 2016年第5期9卷 639-649页

作者： Christine m. Kraus Kathy R. m.nkvold gregory B. m.rtin Boyce Thom.son Institute for Plant Research Ithaca NY 14853 USA Plant Pathology and Plant-m.crobe Biology Section School of Integrative Plant Science Cornell University Ithaca NY 14853 USA Beckm.n Coulter Indianapolis IN 46268 USA

The Pto protein kinase from.Solanum.pim.inellifolium.interacts with Pseudom.nas syringae effectors AvrPto or AvrPtoB to activate effector-triggered im.unity. The previously solved crystal structures of the AvrPto-Pto and AvrPtoB-Pto com.lexes revealed that Pro binds each effector through both a shared and a unique interface. Hera we use natural variation in wild species of tom.to to further investigate Pto recognition of these two effectors. One species, Solanum.chm.elewskU, was found to have m.ny accessions that recognize only AvrPtoB. The Pto ortholog from.one of these accessions was responsible for recognition of AvrPtoB and it differed from.Solanum.pim.inellifolium.Pto by only 14 am.no acids, including two in the AvrPto-specific interface, glutam.te-49/glycine-51. Converting these two residues to those in Pro （histidine-49/valine-51） did not restore recognition of AvrPto. Subsequent experim.nts revealed that a single substitution of a histidine-to-aspartate at position 193 in Pto, which is not near the AvrPto- specific interface, was sufficient for conferring recognRion of AvrPto in plant cells. The reciprocal substi- tution of aspartate-to-histidine-193 in Pto abolished AvrPto recognition, confirm.ng the im.ortance of this residue. Our results reveal new aspects about effector recognition by Pto and dem.nstrate the value of using natural variation to understand the interaction between resistance proteins and pathogen effectors.

关键词： Effector-triggered im.unity natural variation plant im.unity Pseudom.nas syringae Pto tom.to

Near equilibrium.dynam.cs and one-dim.nsional spatial–tem.oral structures of polar active liquid crystals

维普期刊数据库评论

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 Physics B 2014年第11期23卷 75-100页

作者：杨小刚 m.gregory Forest 王奇 School of m.them.tical Sciences Nankai University Departm.nt of m.them.tics University of North Carolina at Chapel Hill Departm.nt of m.them.tics Interdisciplinary Mathematics Institute and NanoCenter at USC University of South Carolina Beijing Com.utational Science Research Center

We system.tically explore near equilibrium. flow-driven, and flow-activity coupled dynam.cs of polar active liquid crystals using a continuum.m.del. Firstly, we re-derive the hydrodynam.c m.del to ensure the therm.dynam.c laws are obeyed and elastic stresses and forces are consistently accounted. We then carry out a linear stability analysis about constant steady states to study near equilibrium.dynam.cs around the steady states, revealing long-wave instability inherent in this m.del system.and how active param.ters in the m.del affect the instability. We then study m.del predictions for one- dim.nsional （1D） spatial-tem.oral structures of active liquid crystals in a channel subject to physical boundary conditions. We discuss the m.del prediction in two selected regim.s, one is the viscous stress dom.nated regim., also known as the flow-driven regim., while the other is the full regim., in which all active m.chanism. are included. In the viscous stress dom.nated regim., the polarity vector is driven by the prescribed flow field. Dynam.cs depend sensitively on the physical boundary condition and the type of the driven flow field. Bulk-dom.nated tem.oral periodic states and spatially hom.geneous states are possible under weak anchoring conditions while spatially inhom.geneous states exist under strong anchoring conditions. In the full m.del, flow-orientation interaction generates a host of planar as well as out-of-plane spatial-tem.oral structures related to the spontaneous flows due to the m.lecular self-propelled m.tion. These results provide contact with the recent literature on active nem.tic suspensions. In addition, sym.etry breaking pattem. em.rge as the additional active viscous stress due to the polarity vector is included in the force balance. The inertia effect is found to lim.t the long-tim. survival of spatial structures to those with sm.ll wave num.ers, i.e., an asym.totic coarsening to long wave structures. A rich set of m.chanism. for generating and li

关键词： active liquid crystals active particles spatial-tem.oral structures spontaneous flows

Exploiting Lateral Resolution of Near-Surface Seism.c Refraction m.thods

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Geosciences 2009年第3期20卷 526-545页

作者： Derecke palmer School of Biological Earth and Environmental Sciences The University of New South WalesSydney 2052 Australia

The 1D τ-p inversion algorithm.is widely em.loyed to generate starting m.dels with m.st com.uter program. that im.lem.nt refraction tom.graphy. However, this algorithm.em.hasizes the vertical resolution of m.ny layers, and as a result, it frequently fails to detect even large lateral variations in seism.c velocities, such as the decreases that are indicative of shear zones. This study presents a case that dem.nstrates the failure of the 1D τ-p inversion algorithm.to define or even detect a m.jor shear zone that is 50 m.or ten stations wide. Furtherm.re, the m.jority of refraction tom.graphy program. param.terize the seism.c velocities within each layer with vertical velocity gradients. By contrast, the 2D generalized reciprocal m.thod （GRm. inversion algorithm. em.hasize the lateral resolution of individual layers. This study dem.nstrates the successful detection and definition of the 50-m.wide shear zone with the GRm.inversion algorithm.. The existence of the shear zone is corroborated by a 2D analysis of the head wave am.litudes and by num.rous closely spaced orthogonal seism.c profiles carried out as part of a later 3D refraction investigation. Furtherm.re, a 1D analysis of the head wave am.litudes indicates that a reversal in the seism.c velocities, rather than vertical velocity gradients, occurs in the weathered layers. While all seism.c refraction operations should aim.to provide as accurate depth estim.tes as is practical, the m.jor conclusion reached in this study is that refraction inversion algorithm. that em.hasize the lateral resolution of individual layers generate m.re useful results for geotechnical and environm.ntal applications. The advantages of the im.roved lateral resolution are obtained with 2D profiles in which the structural features can be recognized from.the m.gnitudes of the variations in the seism.c velocities. Furtherm.re, the spatial patterns obtained with 3D investigations facilitate the recognition of structural features that do not di

关键词： am.litude GRm near-surface refraction convolution section resolution seism.c refraction 2D 3D.

Sm.ller and bolder prey snails have higher survival in staged encounters with the sea star Pisaster giganteus

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2017年第6期63卷 633-638页

作者： William.C. FOSTER Connor m. ARm.TRONG gregory T. CHISm.Jonathan N. PRUITT Departm.nt of Ecology Evolution and Marine Biology University of California Santa Barbara Santa Barbara CA93180 USA

Tem.orally consistent individual differences in behavior, also known as anim.l personality, can have large im.acts on individual fitness. Here, we explore the degree to which individual differences in anti-predator response （or boldness） influence survival rates in groups of snails Chlorostom. funebralis when they encounter a predatory sea star Pisaster giganteus. The snail C. funebralis shows consistent individual variation in predator response where som. fearful snails actively flee bodies of water occupied by predators whereas bolder snails consistently do not. We show here that bold snails are significantly m.re likely to survive encounters with a predatory sea star and, som.what counterintuitively, fearful snails actually suffer higher m.rtality rates. We also found that sm.ller snails and those occurring at higher experim.ntal densities experienced higher per capita survival rates. Positive effects of prey boldness on survival are not uncom.only reported in the anim.l personality literature; however, such results are inconsistent with classic anim.l personality theory borrowed from.the optim.l foraging literature. The findings herein add to the growing body of evidence that consistent individual differences in behavior can im.act predator-prey interactions and that boldness is potentially under positive predator-driven selection in som. system..

关键词： behavioral syndrom. behavioral type predation risk personality survival selection tem.eram.nt.