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Search Results: 1 - 10 of 227600 matches for " Morgan R Stuart "
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Effects of the neurological wake-up test on clinical examination, intracranial pressure, brain metabolism and brain tissue oxygenation in severely brain-injured patients
Raimund Helbok, Pedro Kurtz, Michael J Schmidt, Morgan R Stuart, Luis Fernandez, Sander E Connolly, Kiwon Lee, Erich Schmutzhard, Stephan A Mayer, Jan Claassen, Neeraj Badjatia
Critical Care , 2012, DOI: 10.1186/cc11880
Abstract: This prospective observational study was performed in a neuroscience intensive care unit in a tertiary-care academic center. Twenty consecutive severely brain-injured patients with multimodal neuromonitoring were analyzed for levels of brain lactate, pyruvate and glucose, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and brain tissue oxygen tension (PbtO2) during IS trials.Of the 82 trial days, 54 IS-trials were performed as interruption of sedation and analgesics were not considered safe on 28 days (34%). An increase in the FOUR Score (Full Outline of UnResponsiveness score) was observed in 50% of IS-trials by a median of three (two to four) points. Detection of a new neurologic deficit occurred in one trial (2%), and in one-third of IS-trials the trial had to be stopped due to an ICP-crisis (> 20 mmHg), agitation or systemic desaturation. In IS-trials that had to be aborted, a significant increase in ICP and decrease in PbtO2 (P < 0.05), including 67% with critical values of PbtO2 < 20 mmHg, a tendency to brain metabolic distress (P < 0.07) was observed.Interruption of sedation revealed new relevant clinical information in only one trial and a large number of trials could not be performed or had to be stopped due to safety issues. Weighing pros and cons of IS-trials in patients with acute brain injury seems important as related side effects may overcome the clinical benefit.Titrating sedatives and analgesics to achieve the right balance between deep sedation and wakefulness and to ameliorate patients' comfort in the intensive care unit (ICU) is an integral part of critical care [1]. Over-sedation can lead to prolonged duration of mechanical ventilation and ICU stay and increase the incidence of secondary complications, including nosocomial infections and delirium.Daily interruption of sedation trials (IS-trials) have been implemented in many surgical and medical ICUs after randomized controlled trials demonstrated that IS decreased the duration of
Adjuvant Chemotherapy for Brain Tumors Delivered via a Novel Intra-Cavity Moldable Polymer Matrix
Cheryl V. Rahman, Stuart J. Smith, Paul S. Morgan, Keith A. Langmack, Phil A. Clarke, Alison A. Ritchie, Donald C. Macarthur, Felicity R. Rose, Kevin M. Shakesheff, Richard G. Grundy, Ruman Rahman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077435
Abstract: Introduction Polymer-based delivery systems offer innovative intra-cavity administration of drugs, with the potential to better target micro-deposits of cancer cells in brain parenchyma beyond the resected cavity. Here we evaluate clinical utility, toxicity and sustained drug release capability of a novel formulation of poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) microparticles. Methods PLGA/PEG microparticle-based matrices were molded around an ex vivo brain pseudo-resection cavity and analyzed using magnetic resonance imaging and computerized tomography. In vitro toxicity of the polymer was assessed using tumor and endothelial cells and drug release from trichostatin A-, etoposide- and methotrexate-loaded matrices was determined. To verify activity of released agents, tumor cells were seeded onto drug-loaded matrices and viability assessed. Results PLGA/PEG matrices can be molded around a pseudo-resection cavity wall with no polymer-related artifact on clinical scans. The polymer withstands fractionated radiotherapy, with no disruption of microparticle structure. No toxicity was evident when tumor or endothelial cells were grown on control matrices in vitro. Trichostatin A, etoposide and methotrexate were released from the matrices over a 3-4 week period in vitro and etoposide released over 3 days in vivo, with released agents retaining cytotoxic capabilities. PLGA/PEG microparticle-based matrices molded around a resection cavity wall are distinguishable in clinical scanning modalities. Matrices are non-toxic in vitro suggesting good biocompatibility in vivo. Active trichostatin A, etoposide and methotrexate can be incorporated and released gradually from matrices, with radiotherapy unlikely to interfere with release. Conclusion The PLGA/PEG delivery system offers an innovative intra-cavity approach to administer chemotherapeutics for improved local control of malignant brain tumors.
Accuracy of Stream Habitat Interpolations Across Spatial Scales  [PDF]
Kenneth R. Sheehan, Stuart A. Welsh
Journal of Geographic Information System (JGIS) , 2013, DOI: 10.4236/jgis.2013.56057
Abstract:

Stream habitat data are often collected across spatial scales because relationships among habitat, species occurrence, and management plans are linked at multiple spatial scales. Unfortunately, scale is often a factor limiting insight gained from spatial analysis of stream habitat data. Considerable cost is often expended to collect data at several spatial scales to provide accurate evaluation of spatial relationships in streams. To address utility of single scale set of stream habitat data used at varying scales, we examined the influence that data scaling had on accuracy of natural neighbor predictions of depth, flow, and benthic substrate. To achieve this goal, we measured two streams at gridded resolution of 0.33 × 0.33 meter cell size over a combined area of 934 m2 to create a baseline for natural neighbor interpolated maps at 12 incremental scales ranging from a raster cell size of 0.11 m2 to 16 m2. Analysis of predictive maps showed a logarithmic linear decay pattern in RMSE values in interpolation accuracy for variables as resolution of data used to interpolate study areas became coarser. Proportional accuracy of interpolated models (r2) decreased, but it was maintained up to 78% as interpolation scale moved from 0.11 m2 to 16 m2. Results indicated that accuracy retention was suitable for assessment and management purposes at various scales different from the data collection scale. Our study is relevant to spatial modeling, fish habitat assessment, and stream habitat management because it highlights the potential of using a single dataset to fulfill analysis needs rather than investing considerable cost to develop several scaled datasets

Immunology of term and preterm labor
Morgan R Peltier
Reproductive Biology and Endocrinology , 2003, DOI: 10.1186/1477-7827-1-122
Abstract: Preterm labor (PTL) and delivery (PTD) is the foremost problem in modern obstetrics and is defined as labor or birth before 37 weeks gestation (relative to the last menstrual period). Preterm labor is preceded about 30% of the time by preterm, pre-mature rupture of membranes (PPROM), which is defined as membrane rupture prior to 37 weeks gestation. In the older literature all babies that were born less than 2500 g were considered to be premature. Later studies, using better methods of gestational dating, however, revealed that many of these infants were actually delivered at term but were small because of decreased fetal growth (intrauterine growth restriction – IUGR). Now that growth curves and detailed statistics have been established for babies at all gestational ages, babies that are in the lowest 10th percentile at a given date of delivery are termed small for gestational age (SGA). Although the low birth weight (LBW) statistic (born less that <2500 g without reference to gestational age) does not distinguish between babies that are SGA or the result of preterm delivery, it is still used by epidemiologists because it is easily obtained and useful for populations that lack access to adequate prenatal care or facilities for documenting gestational age at birth.Preterm birth complicated about 11.9% of all pregnancies in 2001 and the number of babies born preterm has been steadily increasing for the past two decades [1]. Despite much effort during the past 40 years, nearly all of the improvements with treating this pregnancy complication have been due to advances in neonatology [2,3]. Indeed, the probability of infant survival for 30 completed weeks of gestation is >90 % and the limit of fetal survival has been extended to 24 weeks [4]. The 2 % of babies born before 32 weeks [1], however, account for about 70 % of all infant mortality and the infants who do survive are frequently plagued with short and long-term respiratory and neurological morbidities such as bron
Planejando para a diferencia o: a experiência de professores de escolas primárias da Irlanda do Norte
Brian McGarvey,Stuart Marriott,Valerie Morgan,Lesley Abbott
Práxis Educativa , 2009,
Abstract: This paper describes how a group of primary schools in Northern Ireland planned a differentiated curriculum, and the extent to which subject co-ordinators offer guidance to teacher colleagues in planning for English, mathematics and science. The views of headteachers, subject co-ordinators and teachers on the ways in which plans are translated into classroom practice for higher and lower attaining pupils in both classwork and homework were obtained. The curriculum support staff described how far they consider teachers are applying the principles of differentiation, including progression and continuity. The results showed that, although most teachers were said to understand the meaning of differentiation moderately well, help was needed in drawing up schemes of work and providing for the extremes of pupil attainment.
Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes
Dean Morgan,Stuart Thom,Elizabeth Winstanley,Phil M. Young
Physics , 2007, DOI: 10.1007/s10714-007-0486-3
Abstract: We study the renormalized stress-energy tensor (RSET) for static quantum states on (n+1)-dimensional, static, spherically symmetric black holes. By solving the conservation equations, we are able to write the stress-energy tensor in terms of a single unknown function of the radial co-ordinate, plus two arbitrary constants. Conditions for the stress-energy tensor to be regular at event horizons (including the extremal and ``ultra-extremal'' cases) are then derived using generalized Kruskal-like co-ordinates. These results should be useful for future calculations of the RSET for static quantum states on spherically symmetric black hole geometries in any number of space-time dimensions.
Merger of white dwarf-neutron star binaries: Prelude to hydrodynamic simulations in general relativity
Vasileios Paschalidis,Morgan MacLeod,Thomas W. Baumgarte,Stuart L. Shapiro
Physics , 2009, DOI: 10.1103/PhysRevD.80.024006
Abstract: White dwarf-neutron star binaries generate detectable gravitational radiation. We construct Newtonian equilibrium models of corotational white dwarf-neutron star (WDNS) binaries in circular orbit and find that these models terminate at the Roche limit. At this point the binary will undergo either stable mass transfer (SMT) and evolve on a secular time scale, or unstable mass transfer (UMT), which results in the tidal disruption of the WD. The path a given binary will follow depends primarily on its mass ratio. We analyze the fate of known WDNS binaries and use population synthesis results to estimate the number of LISA-resolved galactic binaries that will undergo either SMT or UMT. We model the quasistationary SMT epoch by solving a set of simple ordinary differential equations and compute the corresponding gravitational waveforms. Finally, we discuss in general terms the possible fate of binaries that undergo UMT and construct approximate Newtonian equilibrium configurations of merged WDNS remnants. We use these configurations to assess plausible outcomes of our future, fully relativistic simulations of these systems. If sufficient WD debris lands on the NS, the remnant may collapse, whereby the gravitational waves from the inspiral, merger, and collapse phases will sweep from LISA through LIGO frequency bands. If the debris forms a disk about the NS, it may fragment and form planets.
Efficacy and Feasibility of the “Girls’ Recreational Activity Support Program Using Information Technology”: A Pilot Randomised Controlled Trial  [PDF]
Tracey L. Kelty, Philip J. Morgan, David R. Lubans
Advances in Physical Education (APE) , 2012, DOI: 10.4236/ape.2012.21002
Abstract: This study evaluated the effects of the Girls Recreational Activity Support Program Using Information Technology (GRASP-IT) intervention. This group randomized controlled trial for older adolescent girls (15 years+) combined face-to-face sessions with the use of a social network website, Facebook. Baseline and follow-up measurements were taken for physical activity (5 day pedometer), height, weight, estimated VO2max (Queen’s College Step Test), self-efficacy and peer social support. A process evaluation was conducted and included questionnaires and focus groups interviews. Although, the intervention group increased physical activity (mean 1878 steps/day) the difference between groups was not significant (p = 0.11, d = 0.8). BMI, fitness, self-efficacy and peer support all improved for the intervention group, however, changes were not statistically significant between groups. Although participants enjoyed the face-to- face component, engagement with the on-line component was low. Future interventions that utilize Facebook as a medium for increasing physical activity for adolescent girls require additional strategies to improve engagement and compliance.
Throughflow centrality is a global indicator of the functional importance of species in ecosystems
Stuart R. Borrett
Quantitative Biology , 2012, DOI: 10.1016/j.ecolind.2013.03.014
Abstract: To better understand and manage complex systems like ecosystems it is critical to know the relative contribution of system components to system functioning. Ecologists and social scientists have described many ways that individuals can be important; This paper makes two key contributions to this research area. First, it shows that throughflow, the total energy-matter entering or exiting a system component, is a global indicator of the relative contribution of the component to the whole system activity. It is global because it includes the direct and indirect exchanges among community members. Further, throughflow is a special case of Hubbell status as defined in social science. This recognition effectively joins the concepts, enabling ecologists to use and build on the broader centrality research in network science. Second, I characterize the distribution of throughflow in 45 empirically-based trophic ecosystem models. Consistent with expectations, this analysis shows that a small fraction of the system components are responsible for the majority of the system activity. In 73% of the ecosystem models, 20% or less of the nodes generate 80% or more of the total system throughflow. Four or fewer dominant nodes are required to account for 50% of the total system activity. 121 of the 130 dominant nodes in the 45 ecosystem models could be classified as primary producers, dead organic matter, or bacteria. Thus, throughflow centrality indicates the rank power of the ecosystems components and shows the power concentration in the primary production and decomposition cycle. Although these results are specific to ecosystems, these techniques build on flow analysis based on economic input-output analysis. Therefore these results should be useful for ecosystem ecology, industrial ecology, the study of urban metabolism, as well as other domains using input-output analysis.
Suppression of Bromus tectorum L. by Established Perennial Grasses: Potential Mechanisms—Part One
Robert R. Blank,Tye Morgan
Applied and Environmental Soil Science , 2012, DOI: 10.1155/2012/632172
Abstract: Bromus tectorum L. (cheatgrass) is an Eurasian annual grass that has invaded ecosystems throughout the Intermountain west of the United States. Our purpose was to examine mechanisms by which established perennial grasses suppress the growth of B. tectorum. Using rhizotrons, the experiment was conducted over 5 growth cycles: (1) B. tectorum planted between perennial grasses; (2) perennials clipped and B. tectorum planted; (3) perennials clipped and B. tectorum planted into soil mixed with activated carbon; (4) perennials clipped, B. tectorum planted, and top-dressed with fertilizer, and; (5) perennial grasses killed and B. tectorum planted. Water was not limiting in this study. Response variables measured at the end of each growth cycle included above-ground mass and tissue nutrient concentrations. Relative to controls (B. tectorum without competition), established perennial grasses significantly hindered the growth of B. tectorum. Overall, biomass of B. tectorum, grown between established perennials, increased considerably after fertilizer addition and dramatically upon death of the perennials. Potential mechanisms involved in the suppression of B. tectorum include reduced nitrogen (possibly phosphorus) availability and coopting of biological soil space by perennial roots. Our data cannot confirm or reject allelopathic suppression. Understanding the mechanisms involved with suppression may lead to novel control strategies against B. tectorum. 1. Introduction The Eurasian annual grass B. tectorum L. (cheatgrass, downy brome) has come to dominate many ecosystems in the Intermountain Region of the Western United States [1]. Pathways by which B. tectorum facilitate its expansion are myriad and include phenotypic plasticity to new host environments [2], it increases the rates and sizes of wildfires, which fosters more invasion [3], rapid above-and below-ground growth rates [4, 5], prolific seed production [6], landscape disturbance [7–9], and elevated atmospheric CO2 [10, 11]. Given the invasion success of B. tectorum, one might conclude that it is competitive. In the seedling stage, B. tectorum is quite competitive against native and introduced perennial grasses [12–14]. Particular ecosystems, however, are resistant to invasion by B. tectorum [15]. A common thread in ecosystem resistance to B. tectorum invasion is healthy, well-established, perennial grass communities such as the natives Pesudoroegneria spicata (bluebunch wheatgrass), Elymus elymoides (bottlebrush squirreltail), Poa secunda (bluegrass), and Festuca idahoensis (Idaho fescue), and the
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