3,841 research outputs found

    Observational and theoretical studies of the evolving structure of baroclinic waves

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    Dynamical processes involved in comma cloud formation, and passive tracer evolution in a baroclinic wave are discussed. An analytical solution was obtained demonstrating the complex nongeostrophic flow pattern involved in the redistribution of low level constituents in a finite amplitude baroclinic wave, and in the formation of the typical humidity and cloud distributions in such a wave. Observational and theoretical studies of blocking weather patterns in middle latitude flows were studied. The differences in the energy and enstrophy cascades in blocking and nonblocking situations were shown. It was established that pronounced upscale flow of both of these quantities, from intermediate to planetary scales, occurs during blocking episodes. The upscale flux of enstrophy, in particular, suggests that the persistence of blocking periods may be due to reduced dissipation of the large scale circulation and therefore entail some above normal predictability

    A prospective observational study of mycophenolate mofetil treatment in progressive diffuse cutaneous systemic sclerosis of recent onset.

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    OBJECTIVE: A prospective observational study of mycophenolate mofetil (MMF) treatment in patients with diffuse progressive cutaneous systemic sclerosis (SSc) of recent onset. METHODS: Twenty-five previously untreated consecutive patients with recent-onset (\u3c 24 mo) diffuse progressive cutaneous SSc received MMF as the only disease-modifying therapy. Modified Rodnan skin score (mRSS) and affected body surface area (BSA) were compared from initiation of MMF to study end. Pulmonary function tests performed at the same institution before therapy and at study end were available in 15 patients. Histopathology and real-time PCR assessment of fibrosis-related gene expression were performed before and after treatment in skin biopsies from 3 patients. RESULTS: At 18.2 ± 8.73 months of MMF therapy (median 2000 mg/day) the mRSS decreased from 24.56 ± 8.62 to 14.52 ± 10.9 (p = 0.0004) and the affected BSA from 36% ± 16% to 14% ± 13.3% (p = 0.00001). Pulmonary function tests remained stable from initiation of MMF to the end of the study. Skin histopathology showed a remarkable reduction in accumulation of fibrotic tissue. Real-time PCR of skin biopsies demonstrated a marked decrease in expression of fibrosis-related genes. CONCLUSION: Patients with diffuse progressive cutaneous SSc of recent onset treated with MMF experienced marked improvement in skin involvement and stabilization of pulmonary function. Skin biopsies from 3 patients demonstrated histopathological improvement and decreased expression of fibrosis-related genes

    Metastasis Update: Human Prostate Carcinoma Invasion via Tubulogenesis

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    This paper proposes that human prostate carcinoma primarily invades as a cohesive cell collective through a mechanism similar to embryonic tubulogenesis, instead of the popular epithelial-mesenchymal transformation (EMT) model. Evidence supporting a tubulogenesis model is presented, along with suggestions for additional research. Additionally, observations documenting cell adhesion molecule changes in tissue and stromal components are reviewed, allowing for comparisons between the current branching morphogenesis models and the tubulogenesis model. Finally, the implications of this model on prevailing views of therapeutic and diagnostic strategies for aggressive prostatic disease are considered

    Ultrafiltration coefficient and glomerular capillary resistance in a model of immune complex glomerulonephritis

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    Ultrafiltration coefficient and glomerular capillary resistance in a model of immune complex glomerulonephritis. Decreased ultrafiltration coefficient, LpA or Kf, was documented previously in micropuncture studies of glomerulonephritis in rats. Observations were made immediately following an injection of antiglomerular basement membrane (anti-GBM) antibody, later in the course of glomerulonephritis, and during the chronic phase of Heymann nephritis. To gain further insight into the basis of reduced glomerular filtration rate in immune-complex glomerulonephritis, we studied the anatomic, physiologic, and rheologic properties of isolated glomeruli from female Buffalo rats with nephritis which developed during infection withTrypanosoma rhodesiense. Immune-complex mediated glomerulonephritis was present 2 weeks after inoculation and progressed throughout the 4 weeks of study. Renal insufficiency occurred, with serum creatinine concentrations rising to 5 to 10 times control values by week 4. Mesangial hypercellularity, mesangial electron dense deposits, and endothelial cell swelling were observed. Increased numbers of mononuclear cells were present within the glomerulus. Total glomerular water volume was greater in nephritic than in normal animals. Increased cell volume accounted for most of the volume increment. When filtration into the capillaries was induced in vitro by imposing an oncotic gradient of 6.5mm Hg or greater across the capillary wall, rapid and uniform erythrocyte movement occurred within the capillaries of control glomeruli and erythrocytes were ejected into the medium. In contrast, a transcapillary gradient of 30 to 40mm Hg was required to produce erythrocyte movement in glomeruli from nephritic animals studied 4 weeks after inoculation. The ultrafiltration coefficient of nephritic glomeruli was estimated in vitro and was not different from that of control glomeruli (5.81 ± 0.35 vs. 6.21 ± 0.49 nl/minmm Hg). An impairment of capillary perfusion may be responsible for the decreased rate of glomerular filtration observed in this model of glomerulonephritis.Evaluation in vitro du coefficient d'ultrafiltration et de la résistance capillaire glomérulaire dans un modèle de glomérulonéphrite des comples immuns. La diminution du coefficient d'ultrafiltration, LpA ou Kf, a été établie précédement au cours de travaux utilisant les microponctions chez des rats atteints de glomérulonéphrite, immédiatement après l'injection d'anti-corps anti-membrane basale glomérulaire (anti-GBM) et, ultérieurement, au cours de l'évolution de glomérulonéphrite et durant la phase chronique de la néphrite de Heymann. Afin d'obtenir plus d'informations sur les fondements de la diminution du débit de filtration glomérulaire au cours de la néphrite des complexes immuns, nous avons étudié les propriétés anatomiques, physiologiques, et biologiques des glomérules isolés de rats femelles de la souche Buffalo atteints de néphrite développée au cours de l'infection parTrypanosoma rhodesiense. Une glomérulonéphrite des complexes immuns existait deux semaines après l'inoculation et évoluait pendant les 4 semaines de l'étude. Il existait une insuffisance rénale et la créatinine sérique atteignait des valeurs 5 à 10 fois plus grandes que les contrôles à la 4 semaine. L'hypercellularité mésangiale, sous la forme de dépôts denses mésangiaux en microscopie électronique, et le gonflement des cellules endothéliales ont été observés. Le nombre des cellules mononucléés du glomérule était augmenté. Le volume total d'eau du glomérule était plus grand chez les animaux atteints de néphrite que chez les contrôles. L'augmentation du volume cellulaire rendait compte de la plus grande partie de l'augmentation de volume. Quand la filtration dans les capillaires a été declenchée par l'imposition d'un gradient oncotique de 6,5mm Hg ou plus à travers la paroi capillaire, un mouvement rapide et uniforme des érythrocytes est apparu et les érythrocytes ont été éjectés dans le milieu. Par contre, pour les glomérules provenant d'animaux néphritiques, étudiés quatre semaines après l'inoculation, un gradient de 30 à 40mm Hg était nécessaire pour produire un mouvement des érythrocytes. Le coefficient d'ultrafiltration des glomérules d'animaux néphritiques a été évalué in vitro et n'est pas différent de celui des animaux contrôles (5,81 ± 0,35 vs. 6,21 ± 0,49 nl/minmm Hg). L'altération de la perfusion capillaire est responsable de la diminution du débit de filtration glomérulaire observée dans ce modèle de glomérulonéphrite

    A Nuclear Physics Program at the ATLAS Experiment at the CERN Large Hadron Collider

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    The ATLAS collaboration has significant interest in the physics of ultra-relativistic heavy ion collisions. We submitted a Letter of Intent to the United States Department of Energy in March 2002. The following document is a slightly modified version of that LOI. More details are available at: http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/SM/ionsComment: Letter of Intent submitted to the United States Department of Energy Nuclear Physics Division in March 2002 (revised version

    Testing Linear-Invariant Non-Linear Properties

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    We consider the task of testing properties of Boolean functions that are invariant under linear transformations of the Boolean cube. Previous work in property testing, including the linearity test and the test for Reed-Muller codes, has mostly focused on such tasks for linear properties. The one exception is a test due to Green for "triangle freeness": a function f:\cube^{n}\to\cube satisfies this property if f(x),f(y),f(x+y)f(x),f(y),f(x+y) do not all equal 1, for any pair x,y\in\cube^{n}. Here we extend this test to a more systematic study of testing for linear-invariant non-linear properties. We consider properties that are described by a single forbidden pattern (and its linear transformations), i.e., a property is given by kk points v_{1},...,v_{k}\in\cube^{k} and f:\cube^{n}\to\cube satisfies the property that if for all linear maps L:\cube^{k}\to\cube^{n} it is the case that f(L(v1)),...,f(L(vk))f(L(v_{1})),...,f(L(v_{k})) do not all equal 1. We show that this property is testable if the underlying matroid specified by v1,...,vkv_{1},...,v_{k} is a graphic matroid. This extends Green's result to an infinite class of new properties. Our techniques extend those of Green and in particular we establish a link between the notion of "1-complexity linear systems" of Green and Tao, and graphic matroids, to derive the results.Comment: This is the full version; conference version appeared in the proceedings of STACS 200

    The Kasteleyn model and a cellular automaton approach to traffic flow

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    We propose a bridge between the theory of exactly solvable models and the investigation of traffic flow. By choosing the activities in an apropriate way the dimer configurations of the Kasteleyn model on a hexagonal lattice can be interpreted as space-time trajectories of cars. This then allows for a calculation of the flow-density relationship (fundamental diagram). We further introduce a closely-related cellular automaton model. This model can be viewed as a variant of the Nagel-Schreckenberg model in which the cars do not have a velocity memory. It is also exactly solvable and the fundamental diagram is calculated.Comment: Latex, 13 pages including 3 ps-figure

    Organisational interventions designed to reduce caesarean section rates: a systematic review protocol.

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    INTRODUCTION: There is a growing body of evidence to indicate that both primary and subsequent caesarean sections are associated with increased maternal and perinatal morbidity. Efforts to reduce the number of clinically unnecessary caesarean sections are urgently required. Our objective is to systematically review published evidence on the effectiveness of maternity service organisational interventions, such as models of maternity care, that aim to reduce caesarean section rates. METHODS AND ANALYSIS: Databases will be searched, including the Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, MEDLINE, Maternity and Infant Care, EMBASE and SCOPUS. Search terms related to caesarean section and organisational intervention will be used. Research published before 1980 will be excluded and only randomised controlled trials, cluster-randomised controlled trials, quasi-randomised controlled trials, controlled before and after studies and interrupted time series studies will be included. Data extraction and quality assessments will be undertaken by two authors. ETHICS AND DISSEMINATION: Ethics approval is not required for this systematic review. The results of this study will be disseminated via peer-reviewed publication and presentation at professional conferences. PROSPERO REGISTRATION NUMBER: CRD42016039458
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