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Near equilibrium dynamics and one-dimensional spatial–temporal structures of polar active liquid crystals

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 mathematical Sciences Nankai University Department of mathematics University of North Carolina at Chapel Hill Department of mathematics Interdisciplinary Mathematics Institute and NanoCenter at USC University of South Carolina Beijing Computational Science Research Center

We systematically explore near equilibrium, flow-driven, and flow-activity coupled dynamics of polar active liquid crystals using a continuum model. Firstly, we re-derive the hydrodynamic model to ensure the thermodynamic 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 dynamics around the steady states, revealing long-wave instability inherent in this model system and how active parameters in the model affect the instability. We then study model predictions for one- dimensional （1D） spatial-temporal structures of active liquid crystals in a channel subject to physical boundary conditions. We discuss the model prediction in two selected regimes, one is the viscous stress dominated regime, also known as the flow-driven regime, while the other is the full regime, in which all active mechanisms are included. In the viscous stress dominated regime, the polarity vector is driven by the prescribed flow field. Dynamics depend sensitively on the physical boundary condition and the type of the driven flow field. Bulk-dominated temporal periodic states and spatially homogeneous states are possible under weak anchoring conditions while spatially inhomogeneous states exist under strong anchoring conditions. In the full model, flow-orientation interaction generates a host of planar as well as out-of-plane spatial-temporal structures related to the spontaneous flows due to the molecular self-propelled motion. These results provide contact with the recent literature on active nematic suspensions. In addition, symmetry breaking pattems emerge as the additional active viscous stress due to the polarity vector is included in the force balance. The inertia effect is found to limit the long-time survival of spatial structures to those with small wave numbers, i.e., an asymptotic coarsening to long wave structures. A rich set of mechanisms for generating and li

关键词： active liquid crystals active particles spatial-temporal structures spontaneous flows

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A 2-D Kinetic Theory for Flows of monodomain Polymer-Rod Nanocomposites

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Communications in Computational Physics 2010年第2期7卷 250-282页

作者： m.gregory forest Qingqing Liao Qi Wang Department of mathematics University of North Carolina at Chapel HillChapel HillNC 27599USA Department of mathematics University of South CarolinaColumbiaSC 29208USA Department of mathematics and NanoCenter at USC University of South CarolinaColumbiaSC 29208USA

We merge classical kinetic theories [m. Doi and S. F. Edwards, The Theoryof Polymer Dynamics, 1986] for viscous dispersions of rigid rods, extended to semi-flexibility [A. R. Khokhlov and A. N. Semenov, macromolecules, 17 (1984), pp. 2678-2685], and for Rouse flexible chains to model the hydrodynamics of polymer nano-rodcomposites (PNCs). A mean-field potential for the polymer-rod interface provides thekey coupling between the two phases. We restrict this first study to two-dimensionalconformational space. We solve the coupled set of Smoluchowski equations for threebenchmark experiments. First we explore how rod semi-flexibility and the polymer-rod interface alter the Onsager equilibrium phase diagram. Then we determine mon-odomain phase behavior of PNCs for imposed simple elongation and shear, respec-tively. These results inform the effects that each phase has on the other as parametricstrengths of the interactions are varied in the context of the most basic rheological ex-periments.

关键词： Kinetic theory polymer nanorod nanocomposites monodomains equilibrium elon-gation shear

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Assessing risks from mining-induced ground movements near gas wells

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International Journal of mining Science and Technology 2020年第1期30卷 11-16页

作者： Christopher mark gregory m.Rumbaugh mine Safety and Health Administration PittsburghPAUSA

The proliferation of unconventional gas well development in the Northern Appalachian coalfields has raised a number of mine safety *** wells,which extract gas from deep shale formations,are characterized by gas volumes and pressures that are significantly higher than those observed at many conventional *** gas is composed largely of methane as well as other *** of planned and actively producing wells penetrate protective coal pillars or barriers within active mine boundaries,including chain pillars located between longwall *** released from a well damaged by mining-induced ground movements could pose a risk to miners by flowing into the mine *** mining-induced ground movements that may cause well damage include conventional subsidence,non-conventional subsidence(*** plane slip),pillar failure,and floor *** paper describes the known risk factors for each of the four failure *** includes a framework that can guide the risk assessment process when mining takes place near gas or oil wells.

关键词： Gas well Subsidence Coal protection pillar Risk matrix Longwall mining

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

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forest Ecosystems 2018年第1期5卷 53-61页

作者： Brett m. Bennett gregory A. Barton School of Humanities and Communication Arts Western Sydney UniversityLocked Bag 1797PenrithNSW 2751Australia Department 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 magnifiers that increase rainfall at regional scales. Supply-side scholars seek to challenge the dominance of demand-side thinking. The demand-side school emphasizes that trees are net users of water within a catchment that decrease overall water available for other users. This scientific debate has significant implications for the development of policies to manage forests and water. Results： Scientists have debated the question of whether forests improve or worsen water balance for over two hundred years. Connections between forests and rainfall gained prominence 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 climate 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 determining rainfall. The forest-rainfall connection reemerged in the 1980s alongside advances in climate modelling and growing fears of anthropogenic global warming and tropical deforestation. Using new data and theories, supply-side advocates have once again placed a strong forest-rainfall connection into scientific prominence. Conclusion： Supply-side management policies have a checkered history that should elicit caution, while demand-side policies, which are based on almost a century of hydrolog

关键词： Climate change Environmental history forests Hydrology Rain Water

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management of stage Ⅳ rectal cancer: Palliative options

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World Journal of Gastroenterology 2011年第7期17卷 835-847页

作者： Sean m Ronnekleiv-Kelly gregory D Kennedy Department of Surgery Section of Colon and Rectal Surgery University of Wisconsin School of Medicine and Public Health 600 HighlandAvenue G4/701A CSC Madison WI 53792 United States

Approximately 30% of patients with rectal cancer present with metastatic disease. many of these patients have symptoms of bleeding or obstruction. Several treatment options are available to deal with the various complications that may afflict these patients. Endorectal stenting, laser ablation, and operative resection are a few of the options available to the patient with a malignant large bowel obstruction. A thorough understanding of treatment options will ensure the patient is offered the most effective therapy with the least amount of associated morbidity. In this review, we describe various options for palliation of symptoms in patients with metastatic rectal cancer. Additionally, we briefly discuss treatment for asymptomatic patients with metastatic disease.

关键词： Palliative therapy Rectal cancer malignant bleeding malignant obstruction Endorectal stenting Laser ablation

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Spherical Parameterization of marching Cubes IsoSurfaces Based upon Nearest Neighbor Coordinates

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Journal of Computer Science & Technology 2009年第1期24卷 30-38页

作者： gregory m.Nielson 张丽艳李建黄辉扬 Arizona State University TempeAZU.S.A. Nanjing University of Aeronautics and Astronautics Handong Global University National Central University

We present some new methods for parameterizing the triangle mesh surface （TmS） which result from the marching Cubes （mC） algorithm. The methods apply to surfaces of genus zero and the parameter domain is a unit sphere. We take advantage of some special properties of the TmS resulting from the mC algorithm to obtain simple, computational efficient representations of the nearest neighbor coordinates and utilize these coordinates in the characterization of the parameterization by means of systems of equations which are solved iteratively. Examples and comparisons are presented.

关键词： isosurface marching cubes mapping parameterization spherical triangle mesh surface

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Altered physiology of gastrointestinal vagal afferents following neurotrauma

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

作者： Emily N.Blanke gregory m.Holmes Emily m.Besecker Department of Health Sciences Gettysburg CollegeGettysburgPAUSA Department of Neural and Behavioral Sciences Penn State University College of MedicineHersheyPAUSA

The adaptability of the central nervous system has been revealed in several model *** particular interest to central nervous system-injured individuals is the ability for neural components to be modified for regain of *** both types of neurotrauma,traumatic brain injury and spinal cord injury,the primary parasympathetic control to the gastrointestinal tract,the vagus nerve,remains anatomically ***,individuals with traumatic brain injury or spinal cord injury are highly susceptible to gastrointestinal *** gastrointestinal dysfunctions attribute to higher morbidity and mortality following traumatic brain injury and spinal cord *** the vagal efferent output remains capable of eliciting motor responses following injury,evidence suggests impairment of the vagal *** sensory input drives motor output,this review will discuss the normal and altered anatomy and physiology of the gastrointestinal vagal afferents to better understand the contributions of vagal afferent plasticity following neurotrauma.

关键词： gastrointestinal functions microbiome neurotrauma nodose ganglia sensory neuropathy spinal cord injury traumatic brain injury vagal afferents visceral reflexes

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Investigating neurogenic bowel in experimental spinal cord injury: where to begin?

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Neural Regeneration Research 2019年第2期14卷 222-226页

作者： Amanda R.White gregory m.Holmes Department of Neural & Behavioral Sciences Penn State University College of Medicine

The devastating losses following traumatic spinal cord injury(SCI) encompass the motor, sensory and autonomic nervous systems. Neurogenic bowel is a slow transit colonic dysfunction marked by constipation, rectal evacuation difficulties, decreased anorectal sensation, fecal incontinence or some combination thereof. Furthermore, neurogenic bowel is one of the most prevalent comorbidities of SCI and is recognized by afflicted individuals and caregivers as a lifelong physical and psychological challenge that profoundly affects quality of life. The restoration of post-injury control of movement has received considerable scientific scrutiny yet the daily necessity of voiding the bowel and bladder remains critically under-investigated. Subsequently, physicians and caregivers are rarely presented with consistent, evidence-based strategies to successfully address the consequences of dysregulated voiding reflexes. Neurogenic bowel is commonly believed to result from the interruption of the supraspinal control of the spinal autonomic circuits regulating the colon. In this mini-review, we discuss the clinical challenges presented by neurogenic bowel and emerging pre-clinical evidence that is revealing that SCI also initiates functional remodeling of the colonic wall concurrent with a decrease in local enteric neurons. Since the enteric input to the colonic smooth muscle is the final common pathway for functional contractions of the colon, changes to the neuromuscular interface must first be understood in order to maximize the efficacy of therapeutic interventions targeting colonic dysfunction following SCI.

关键词： colon enteric nervous system parasympathetic sympathetic autonomic nervous system defecationreflexes gastrointestinal inflammation constipation incontinence

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Angiographic evaluation and management of acute gastrointestinal hemorrhage

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World Journal of Gastroenterology 2012年第11期18卷 1191-1201页

作者： T gregory Walker Gloria m Salazar Arthur C Waltman Division of Vascular Imaging and Intervention Massachusetts General HospitalHarvard Medical SchoolBostonMA 02114United States

Although most cases of acute nonvariceal gastrointestinal hemorrhage either spontaneously resolve or respond to medical management or endoscopic treatment,there are still a significant number of patients who require emergency angiography and transcatheter *** with noninvasive imaging such as nuclear scintigraphy or computed tomography may localize the bleeding source and/or confirm active hemorrhage prior to *** angiographic evaluation should begin with selective catheterization of the artery supplying the most likely site of bleeding,as determined by the available clinical,endoscopic and imaging *** a hemorrhage source is identified,superselective catheterization followed by transcatheter microcoil embolization is usually the most effective means of successfully controlling hemorrhage while minimizing potential *** is now wellrecognized as a viable and safe alternative to emergency *** selected situations transcatheter intra-arterial infusion of vasopressin may also be useful in controlling acute gastrointestinal *** must be aware of the various side effects and potential complications associated with this treatment,however,and recognize the high re-bleeding *** this article we review the current role of angiography,transcatheter arterial embolization and infusion therapy in the evaluation and management of nonvariceal gastrointestinal hemorrhage.

关键词： Angiodysplasia Aneurysm Digital subtrac-tion angiography Contrast media Hemorrhage Radio-nuclide angiography Therapeutic embolization

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Short history of Harry *** mD

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中华显微外科杂志 2020年第1期43卷 I0009-I0010页

作者： gregory m.Buncke 不详

我的父亲哈里本克(Harry ***),被公认为“显微外科之父”。他在格拉斯哥医务室作为专科培训生、师从托马斯吉布森(Thomas Gibson)教授时,便开始对修复直径1 mm的血管感兴趣.在参与Gibson教授的移植免疫学工作以及缩短分离蒂转移时间... 详细信息

我的父亲哈里本克(Harry ***),被公认为“显微外科之父”。他在格拉斯哥医务室作为专科培训生、师从托马斯吉布森(Thomas Gibson)教授时,便开始对修复直径1 mm的血管感兴趣.在参与Gibson教授的移植免疫学工作以及缩短分离蒂转移时间的研究中,Buncke博士便设想仅通过一次手术将营养动脉/静脉修复到受体部位的皮瓣来移植同源组织,从而避免附着皮瓣。

关键词：受体部位专科培训移植免疫学显微外科医务室吉布森托马斯

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