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Search Results: 1 - 10 of 356 matches for " Bret Coughlin "
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The Impact of Enteric Contrast on Radiologist Confidence in Intravenously Enhanced MDCT of the Abdomen and Pelvis: A Randomized Controlled Trial  [PDF]
Christopher M. Garcia, Steven Boe, Bret Coughlin, David M. O’Sullivan, Douglas Moote, Michael T. O’Loughlin, Devika Jajoo, Steve Lee
Advances in Computed Tomography (ACT) , 2014, DOI: 10.4236/act.2014.32004
Abstract:

After Institutional Review Board approval, 109 patients ≥ 18 years old undergoing intravenously enhanced Computed Tomography (CT) of the abdomen and pelvis were prospectively enrolled and randomized into two arms. Patients with a history of inflammatory bowel disease, Crohn disease and ulcerative colitis were excluded. The control arm received routine enteric contrast and intravenous contrast. The experimental arm did not receive oral contrast, but received the standard dose of intravenous (IV) contrast. One of four experienced body radiologists reviewed the studies and rated his/her confidence on a scale of 1 (no confidence) to 10 (all confident findings have been made). Confidence levels were compared between groups. The 109 subjects were distributed 54 (49.5%) in the control arm and 55 (50.5%) in the experimental arm. The average confidence level in the control arm was 8.7 ± 0.9 versus 8.4 ± 1.1 in the experimental arm, which is not statistically significant (p value = 0.09). Among radiologists, the average confidence levels ranged from 6 - 10 in the control arm and 7 - 10 in the experimental arm. No examinations were repeated for technical considerations in either group. No studies were repeated in the experimental group in order to administer oral contrast. When each radiologist was compared to the others, there were no differences in confidence level between pairs in the control arm; however, there were statistically significant differences in confidence level among three pairs of radiologists for the experimental arm. There was no statistically significant difference in radiologist confidence level between intravenously enhanced abdomen and pelvis CTs with enteric contrast and without enteric contrast.

Using the QBO to predict the number of hurricanes hitting the U.S
Katie Coughlin
Physics , 2007,
Abstract: A simple study of the relationship between the QBO and the number of hurricanes in the Atlantic, both in the Basin and hitting the U.S. coastline, demonstrates that the QBO is not a particularly useful index to help predict hurricane numbers on five-year time scales. It is shown that there is very little difference between the number of hurricanes following easterly winds in the equatorial stratosphere and the number that follow westerly winds. Given this it is reasonable one would make better predictions just using the mean number of hurricanes in lieu of using the QBO and this is also simply demonstrated here.
Temps migratoires en tension Tense times for immigration. The production and experiences of temporalities for migrant workers in Lebanon
Julien Bret
Temporalités , 2012,
Abstract: La kafala, système de garantie sur l’étranger propre au monde arabe, produit au Liban un environnement normatif très contraignant pour les migrants non arabes dont elle organise l’immigration : en très grande majorité des femmes, originaires du Sri Lanka et des Philippines, employées domestiques. Elle impose sa temporalité d’institution globale à la migration, et se confronte aux autres temporalités qui structurent l’espace migratoire : celles des individus mobiles, dont la carrière migratoire s’encastre dans la hiérarchie socio-économique de la situation de départ, ainsi que dans dans la hiérarchie des contextes d’accueil ; la temporalité des industries d’émigration, qui développent une rationalité clivée qui leur est propre. Dans cet article, nous souhaitons mettre en scène ces tensions du temps migratoire dans des temporalités en conflit, en évoquant la négativité des rapports sociaux qui en résulte et les contournements normatifs que les migrants et les autres acteurs de cette scène globalisée opèrent dans la poursuite de leurs objectifs. The kafala is a system of guarantee for immigrants in the Arab world. In Lebanon, it produces a highly restrictive regulatory environment for non-Arab migrants; this institution organizes the import of a vast majority of women from Sri Lanka and the Philippines to become domestic employees. It imposes its - as defined - global institution's temporality to migration. It conflicts with the other temporalities that shape the migratory space : temporalities of individuals on the move, whose careers fit into the hierarchy of socio-economic baseline and into the hierarchy between host countries; temporalities of migration industry, that develop a cleaved rationality of their own. In this paper, we want to present the contradiction of migration time and temporalities, in order to understand the resulting negative social relationships. We also study the normative workarounds that migrants and other actors operate in the pursuit of their goals on this globalized scene.
The Tokyo Air Raids in the Words of Those Who Survived, 被災者が語る東京空襲
Bret Fisk
Asia-Pacific Journal : Japan Focus , 2011,
Abstract: This article provides introduces the types of first-person accounts of the civilian experience of the Tokyo air raids. Examples of such accounts are given under the headings: "Complete Personal Narratives," "Incomplete Episodes and Incidents," and "Sites of Mass Suffering."
Transferring a symbolic polynomial expression from \emph{Mathematica} to \emph{Matlab}
A. Bret
Physics , 2010,
Abstract: A \emph{Mathematica} Notebook is presented which allows for the transfer or any kind of polynomial expression to \emph{Matlab}. The output is formatted in such a way that \emph{Matlab} routines such as "Root" can be readily implemented. Once the Notebook has been executed, only one copy-paste operation in necessary.
Beam-plasma dielectric tensor with Mathematica
A. Bret
Physics , 2007,
Abstract: We present a \emph{Mathematica} notebook allowing for the symbolic calculation of the $3\times3$ dielectric tensor of a electron-beam plasma system in the fluid approximation. Calculation is detailed for a cold relativistic electron beam entering a cold magnetized plasma, and for arbitrarily oriented wave vectors. We show how one can elaborate on this example to account for temperatures, arbitrarily oriented magnetic field or a different kind of plasma.
Stable transport in proton driven Fast Ignition
A Bret
Physics , 2009, DOI: 10.1063/1.3213098
Abstract: Proton beam transport in the context of proton driven Fast Ignition is usually assumed to be stable due to protons high inertia, but an analytical analysis of the process is still lacking. The stability of a charge and current neutralized proton beam passing through a plasma is therefore conducted here, for typical proton driven Fast Ignition parameters. In the cold regime, two fast growing Buneman-like modes are found, with an inverse growth-rate much smaller than the beam time-of-flight to the target core. The stability issue is thus not so obvious, and Kinetic effects are investigated. One unstable mode is found stabilized by the background plasma protons and electrons temperatures. The second mode is also damped, providing the proton beam thermal spread is larger than $\sim$ 10 keV. In Fusion conditions, the beam propagation should therefore be stable.
Filamentation instability in a quantum magnetized plasma
A. Bret
Physics , 2008, DOI: 10.1063/1.2844747
Abstract: The filamentation instability occurring when a non relativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified which measures the strength of quantum effects. Strong quantum effects allow for a much smaller magnetic field to suppress the instability than in the classical regime.
CfA Plasma Talks
Antoine Bret
Physics , 2012,
Abstract: Notes from a series of 13 one hour (or more) lectures on Plasma Physics given to Ramesh Narayan' research group at the Harvard-Smithsonian Center for Astrophysics, between January and July 2012. Lectures 1 to 5 cover various key Plasma Physics themes. Lectures 6 to 12 mainly go over the Review Paper on "Multidimensional electron beam-plasma instabilities in the relativistic regime" [\emph{Physics of Plasmas} \textbf{17}, 120501 (2010)]. Lectures 13 talks about the so-called Biermann battery and its ability to generate magnetic fields from scratch.
Robustness of the filamentation instability for asymmetric plasma shells collision in arbitrarily oriented magnetic field
Antoine Bret
Physics , 2013, DOI: 10.1063/1.4825236
Abstract: The filamentation instability triggered when two counter streaming plasma shells overlap appears to be the main mechanism by which collisionless shocks are generated. It has been known for long that a flow aligned magnetic field can completely suppress this instability. In a recent paper [PHYSICS OF PLASMAS 18, 080706 (2011)], it was demonstrated in two dimensions that for the case of two cold, symmetric, relativistically colliding shells, such cancellation cannot occur if the field is not perfectly aligned. Here, this result is extended to the case of two asymmetric shells. The filamentation instability appears therefore as an increasingly robust mechanism to generate shocks.
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