9,313 research outputs found
Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law
In the interaction of high-power laser beams with solid density plasma there
are a number of mechanisms that generate strong magnetic fields. Such fields
subsequently inhibit or redirect electron flows, but can themselves be advected
by heat fluxes, resulting in complex interplay between thermal transport and
magnetic fields.We show that for heating by multiple laser spots reconnection
of magnetic field lines can occur, mediated by these heat fluxes, using a fully
implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection
rate is dictated by heat flows rather than Alfv\`enic flows. We find that this
mechanism is only relevant in a high plasma. However, the Hall
parameter can be large so that thermal transport is
strongly modified by these magnetic fields, which can impact longer time scale
temperature homogeneity and ion dynamics in the system
Total Gastrectomy for Carcinoma of the Stomach
The results of total gastrectomy in 47 patients with carcinoma of the stomach are reported. Extended total gastrectomy is recommended only if the growth cannot be removed by any other means. It should not be performed if the growth is not totally resectable. The operative mortality and postoperative results of total gastrectomy have improved to the extent that this operation for carcinoma of the stomach should be undertaken where indicated
Spatial Burnout in Water Reactors with Nonuniform Startup Distributions of Uranium and Boron
Spatial burnout calculations have been made of two types of water moderated cylindrical reactor using boron as a burnable poison to increase reactor life. Specific reactors studied were a version of the Submarine Advanced Reactor (sAR) and a supercritical water reactor (SCW) . Burnout characteristics such as reactivity excursion, neutron-flux and heat-generation distributions, and uranium and boron distributions have been determined for core lives corresponding to a burnup of approximately 7 kilograms of fully enriched uranium. All reactivity calculations have been based on the actual nonuniform distribution of absorbers existing during intervals of core life. Spatial burnout of uranium and boron and spatial build-up of fission products and equilibrium xenon have been- considered. Calculations were performed on the NACA nuclear reactor simulator using two-group diff'usion theory. The following reactor burnout characteristics have been demonstrated: 1. A significantly lower excursion in reactivity during core life may be obtained by nonuniform rather than uniform startup distribution of uranium. Results for SCW with uranium distributed to provide constant radial heat generation and a core life corresponding to a uranium burnup of 7 kilograms indicated a maximum excursion in reactivity of 2.5 percent. This compared to a maximum excursion of 4.2 percent obtained for the same core life when w'anium was uniformly distributed at startup. Boron was incorporated uniformly in these cores at startup. 2. It is possible to approach constant radial heat generation during the life of a cylindrical core by means of startup nonuniform radial and axial distributions of uranium and boron. Results for SCW with nonuniform radial distribution of uranium to provide constant radial heat generation at startup and with boron for longevity indicate relatively small departures from the initially constant radial heat generation distribution during core life. Results for SAR with a sinusoidal distribution rather than uniform axial distributions of boron indicate significant improvements in axial heat generation distribution during the greater part of core life. 3. Uranium investments for cylindrical reactors with nonuniform radial uranium distributions which provide constant radial heat generation per unit core volume are somewhat higher than for reactors with uniform uranium concentration at startup. On the other hand, uranium investments for reactors with axial boron distributions which approach constant axial heat generation are somewhat smaller than for reactors with uniform boron distributions at startup
The Role of Private Sector Payment Rules and a Proposed Approach for Evaluating Future Changes to Payments Law
Private sector payment organizations should continue to play the primary role in establishing rights and responsibilities for payment transactions between their participating financial institutions, provided that their rules are consistent with customer protections established by federal and state governmental authorities for the customer-financial institution relationship. Current payments law structure, relying on a combination of private sector rules, baseline statutory consumer protections, and (in the case of check payments) a somewhat variable uniform check collection statute, has shown remarkable flexibility in facilitating and responding to the unprecedented scope and pace of change that has occurred in the retail payments world over the last twenty years. The financial services industry should continue to support these two separate spheres of payment laws, private sector rules and government-mandated baseline consumer protection rules. The payment system stakeholders should not attempt to further regulate or limit, either by legislation or by regulation, the ability of private sector payment organizations to establish rules governing the relationships between their participating financial institutions
The Role of Private Sector Payment Rules and a Proposed Approach for Evaluating Future Changes to Payments Law
Private sector payment organizations should continue to play the primary role in establishing rights and responsibilities for payment transactions between their participating financial institutions, provided that their rules are consistent with customer protections established by federal and state governmental authorities for the customer-financial institution relationship. Current payments law structure, relying on a combination of private sector rules, baseline statutory consumer protections, and (in the case of check payments) a somewhat variable uniform check collection statute, has shown remarkable flexibility in facilitating and responding to the unprecedented scope and pace of change that has occurred in the retail payments world over the last twenty years. The financial services industry should continue to support these two separate spheres of payment laws, private sector rules and government-mandated baseline consumer protection rules. The payment system stakeholders should not attempt to further regulate or limit, either by legislation or by regulation, the ability of private sector payment organizations to establish rules governing the relationships between their participating financial institutions
WHOLESALE DEMAND FOR USDA QUALITY GRADED BOXED BEEF AND EFFECTS OF SEASONALITY
This study estimates wholesale demand for pork, chicken, and quality differentiated beef. We estimate meat retailer own- and cross-price demand elasticities for USDA Choice and Select boxed beef. Results indicate that meat retailers have more elastic demand for lower quality graded beef. Retail beef price has a strong positive relationship with Choice and Select boxed beef demand, and a strong negative relationship with wholesale pork and chicken demand. Seasonal analysis reveals demand for both beef quality grades becomes highly price inelastic during the summer months. The two beef quality grades are substitutes during the winter; however, Select beef is not a substitute for Choice beef in the spring and summer.Demand and Price Analysis,
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Leveraging Epidemiology to Improve Risk Assessment.
The field of environmental public health is at an important crossroad. Our current biomonitoring efforts document widespread exposure to a host of chemicals for which toxicity information is lacking. At the same time, advances in the fields of genomics, proteomics, metabolomics, genetics and epigenetics are yielding volumes of data at a rapid pace. Our ability to detect chemicals in biological and environmental media has far outpaced our ability to interpret their health relevance, and as a result, the environmental risk paradigm, in its current state, is antiquated and ill-equipped to make the best use of these new data. In light of new scientific developments and the pressing need to characterize the public health burdens of chemicals, it is imperative to reinvigorate the use of environmental epidemiology in chemical risk assessment. Two case studies of chemical assessments from the Environmental Protection Agency Integrated Risk Information System database are presented to illustrate opportunities where epidemiologic data could have been used in place of experimental animal data in dose-response assessment, or where different approaches, techniques, or studies could have been employed to better utilize existing epidemiologic evidence. Based on the case studies and what can be learned from recent scientific advances and improved approaches to utilizing human data for dose-response estimation, recommendations are provided for the disciplines of epidemiology and risk assessment for enhancing the role of epidemiologic data in hazard identification and dose-response assessment
Serum Immunoglobulins in the Differential Diagnosis Between Intrahepatic Viral Jaundice and Extrahepatic Obstructive Jaundice
Serum immunoglobulin levels are reported in 75 patients with jaundice: 32 with jaundice due to virus hepatitis and 43 with jaundice due to obstruction. The degrees and variations of serum immunoglobulins (Ig), (IgM, IgG and IgA) in virus hepatitis (IH and SH) with jaundice are compared with those found in obstructive jaundice. In 32 of the patients with jaundice from virus hepatitis, serum IgM (100%) and IgG (75%) were elevated above 2 Standard Deviations from the mean values. Neither IgM nor IgG levels were elevated above 2 Standard Deviations from the mean values in 33 of 43 patients (76.7%) with obstructive jaundice. In the other 10 patients, serum IgM (21%) and IgG (7%) were elevated above 2 Standard Devituions from the mean values. Case histories are presented of the five of nine patients, with obstructions and IgM elevations who had inflammatory reactions about the biliary tract
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