12,251 research outputs found

    Evolution of 4 pi observables in the Vlasov-Uehling-Uhlenbeck theory and the transverse momentum transfer as a barometer for hadronic matter

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    We study the dynamics of high energy heavy ion collisions through the Vlasov-Uehling-Uhlenbeck approach. Equilibration is observed, for central collisions. It is shown that the produced entropy, the pion multiplicity, flow angle, and transverse momentum distributions saturate at the moment of maximum compression and temperature. The effects of the nuclear equation of state and the Pauli principle are investigated. For the flow angle distribution there is a 20 deg reduction of the peak flow angle due to the Pauli principle. A stiff equation of state results in a 10–20 deg increase over the soft equation of state at all energies. The transverse momentum at projectile rapidity exhibits a peak structure as a function of impact parameter b. A 40% difference between soft and hard equation of state is observed for the peak impact parameter, i.e., for intermediate multiplicities

    Searching for Keynes: An Essay on the Political Economy of Fiscal Policy, with Application to Canada, 1870-2000 - revised version

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    Keynes' General Theory (1936) is arguably one of the most important books of the twentieth century. His ideas for stabilizing the aggregate economy have profoundly influenced economic theory as well as popular opinion about what governments can and should do with respect to the business cycle. On the other hand, whether Keynesian theory has substantially altered the course of public policy remains an open question. In this paper we identify the elements required for any investigation of the impact of Keynes' ideas on policy choices and then conduct our own 'search for Keynes', applying an intertemporal spatial voting framework to study the fiscal history of the Government of Canada from 1870 to 2000. The long time series allows the construction of a counterfactual – one of several essential elements - showing what governments would have planned to do ‘after Keynes’, if Keynes' ideas had not in fact been present. Our results suggest that textbook Keynesianism is identifiable in the Canadian data.Keynesianism, spatial voting, permanent versus transitory policy, political equilibrium, liquidity constraints

    Political Competition and Convergence to Fundamentals: With Application to the Political Business Cycle and the Size of Government

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    We address the problem of how to investigate whether economics, or politics, or both, matter in the explanation of public policy. The problem is first posed in a particular context by uncovering a political business cycle (using Canadian data for 130 years) and by taking up the challenge to make this fact meaningful by finding a transmission mechanism through actual public choices. Since the cycle is in real growth, and it is reasonable to suppose that public expenditure would be involved, the central task then is to investigate the role of (partisan and opportunistic) political factors, as opposed to economic fundamentals, in the evolution of government size.We proceed by asking whether the data allow us to distinguish between the convergence and the nonconvergence hypotheses. Convergence means that political competition forces public spending to converge in the long run to a level dictated by endowments, tastes and technology. Nonconvergence is taken to mean that political factors other than the degree of political competition prevent convergence to that long run. The general idea here, one that may be applied in any situation where the key issue is the role of economics versus politics over time, is that an overtly political factor can be said to play a distinct role in the evolution of public choices if it can be shown to lead to departures from a dynamic path defined by the evolution of economic fundamentals in a competitive political system.public expenditure, size of government, long run versus short run, opportunism, partisanship, political competition, cointegration

    Investigations of lubricant rheology as applied to elastohydrodynamic lubrication

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    The pressure viscometer was modified to permit the measurement of viscosity at elevated pressures and shear stresses up to 5 x 10 to the 6th power N/sq m (720 psi). This shear stress is within a factor of three of the shear stress occurring in a sliding ehd point contact such as occurs in the ehd simulator. Viscosity data were taken on five lubricant samples, and it was found that viscous heating effects on the viscosity were predominant and not non-Newtonian behavior at the high shear stresses. The development of the infrared temperature measuring technique for the ehd simulator was completed, and temperature data for a set of operating conditions and one lubricant are reported. The numerical analysis of the behavior of nonlinear lubricants in the lubrication of rollers is reported

    Emil Zuckerkandl, M.D. (1849-1910): Bridging Anatomic Study and the Operating Room Table.

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    In the mid-19th century, the Vienna School of Anatomy was at the epicenter of the rapidly growing field of anatomy. One of the school’s most distinguished professors, Hungarian-born anatomist Emil Zuckerkandl was instrumental in transforming anatomy from a descriptive science to one of practical and clinical value. A prolific researcher interested in nearly all areas of morphology and most famously, the chromaffin system, Zuckerkandl’s discoveries from more than a century ago still provide a foundation for surgeons to this day

    Searching for Keynes

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    Mean field effects in hot compressed nuclear matter

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    We study effects of the mean field in hot compressed nuclear matter in the context of the Vlasov Uehling-Uhlenbeck theory. The expansion of a spherical distribution at different temperatures is studied along with collisions of Nb+Nb and Au+Au at lab energies from 50 to 1050 MeV/nucleon. In both the expansion and the actual heavy ion collision simulation, a transition behavior is seen only at the lowest temperature (T<10 MeV) or bombarding energy (E=50 MeV/nucleon), where the attractive part of the mean field is able to bind the expanding matter. At the lowest energy one thus sees the formation of a central residue, whereas at higher bombarding energies there is complete disintegration of the centrally colliding nuclei. The spectrum of emitted nucleons is found to be much hotter than the kinetic energy spectrum of the central emitting region. The extracted temperature slope parameters are in agreement with recent data

    An Update in Guillain-Barré Syndrome

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    Guillain-Barré syndrome (GBS) was first described in 1916 (Guillain G, 1916) and is approaching its 100th anniversary. Our knowledge of the syndrome has hugely expanded since that time. Once originally considered to be only demyelinating in pathology we now recognise both axonal and demyelinating subtypes. Numerous triggering or antecedent events including infections are recognised and GBS is considered an immunological response to these. GBS is now considered to be a clinical syndrome of an acute inflammatory neuropathy encompassing a number of subtypes with evidence of different immunological mechanisms. Some of these are clearly understood while others remain to be fully elucidated. Complement fixing antibodies against peripheral nerve gangliosides alone and in combination are increasingly recognised as an important mechanism of nerve damage. New antibodies against other nerve antigens such as neurofascin have been recently described. Research databases have been set up to look at factors associated with prognosis and the influence of intravenous immunoglobulin (IvIg) pharmacokinetics in therapy. Exciting new studies are in progress to examine a possible role for complement inhibition in the treatment of the syndrome
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