The thermal theory of constant-pressure deflagration for first-order global reactions

The one-dimensional thermal theory of constant-pressure deflagration has been discussed in a recent publication by the senior author and G. Millán. In this paper an explicit relation was given for the linear burning velocity in flames supported by first-order global reactions. It is the purpose of the present analysis to extend this work by dropping the assumptions (a) that the average molecular weight of the gas mixture remains constant, and (b) that the thermal conductivity is constant. As the result, the one-dimensional theory of constant-pressure deflagration described in this paper is complete except in so far as the following reasonable approximations are concerned: (a) a constant average specific heat equal to the ratio of heat release per gram of reactant to total temperature rise may be used; (b) the ideal gas law constitutes a satisfactory equation of state for reacting gas mixtures

Improving the dynamical overlap algorithm

We present algorithmic improvements to the overlap Hybrid Monte Carlo algorithm, including preconditioning techniques and improvements to the correction step, used when one of the eigenvalues of the Kernel operator changes sign, which is now O(\Delta t^2) exact.Comment: 6 pages, 3 figures; poster contribution at Lattice 2005(Algorithms and machines

The journals of importance to UK clinicians: A questionnaire survey of surgeons

Background: Peer-reviewed journals are seen as a major vehicle in the transmission of research findings to clinicians. Perspectives on the importance of individual journals vary and the use of impact factors to assess research is criticised. Other surveys of clinicians suggest a few key journals within a specialty, and sub-specialties, are widely read. Journals with high impact factors are not always widely read or perceived as important. In order to determine whether UK surgeons consider peer-reviewed journals to be important information sources and which journals they read and consider important to inform their clinical practice, we conducted a postal questionnaire survey and then compared the findings with those from a survey of US surgeons. Methods: A questionnaire survey sent to 2,660 UK surgeons asked which information sources they considered to be important and which peer-reviewed journals they read, and perceived as important, to inform their clinical practice. Comparisons were made with numbers of UK NHSfunded surgery publications, journal impact factors and other similar surveys. Results: Peer-reviewed journals were considered to be the second most important information source for UK surgeons. A mode of four journals read was found with academics reading more than non-academics. Two journals, the BMJ and the Annals of the Royal College of Surgeons of England, are prominent across all sub-specialties and others within sub-specialties. The British Journal of Surgery plays a key role within three sub-specialties. UK journals are generally preferred and readership patterns are influenced by membership journals. Some of the journals viewed by surgeons as being most important, for example the Annals of the Royal College of Surgeons of England, do not have high impact factors. Conclusion: Combining the findings from this study with comparable studies highlights the importance of national journals and of membership journals. Our study also illustrates the complexity of the link between the impact factors of journals and the importance of the journals to clinicians. This analysis potentially provides an additional basis on which to assess the role of different journals, and the published output from research

Implications of Results from Z- and WW-Threshold Running

One year of Z- and WW-Threshold running of TESLA can provide the possibility to measure electroweak precision observables to an extremely high accuracy. At the Z peak O(10^9) Z bosons and about 6 10^8 b quarks can be collected. We employ the expected uncertainties \Delta MW = 6 MeV and \Delta sin(theta_W,eff) = 0.00001 and demonstrate in this way that very stringent consistency tests of the Standard Model and the Minimal Supersymmetric Standard Model will be possible. The indirect determination of the Higgs-boson mass within the Standard Model can reach an accuracy of about 5 %. The 6 10^8 b quarks can be used to investigate various b physics topics.Comment: 7 pages, 2 figures, talk given at LCWS99, Sitges, Spain. Two clarifications, one reference adde

Effect of secondary swirl in supersonic gas and plasma flows in self-vacuuming vortex tube

This article presents the results of simulation for a special type of vortex tubes - self-vacuuming vortex tube (SVVT), for which extreme values of temperature separation and vacuum are realized. The main results of this study are the flow structure in the SVVT and energy loss estimations on oblique shock waves, gas friction, instant expansion and organization of vortex bundles in SVVT.Comment: 6 pages, 5 figure

Magnetic field detection in the B2Vn star HR 7355

The B2Vn star HR 7355 is found to be a He-rich magnetic star. Spectropolarimetric data were obtained with FORS1 at UT2 on Paranal observatory to measure the disk-averaged longitudinal magnetic field at various phases of the presumed 0.52 d cycle. A variable magnetic field with strengths between B_z = -2200 and +3200G was found, with confidence limits of 100 to 130G. The field topology is that of an oblique dipole, while the star itself is seen about equator-on. In the intensity spectra the HeI-lines show the typical equivalent width variability of He-strong stars, usually attributed to surface abundance spots. The amplitudes of the equivalent width variability of the HeI lines are extraordinarily strong compared to other cases. These results not only put HR 7355 unambiguously among the early-type magnetic stars, but confirm its outstanding nature: With v sin i = 320 km/s the parameter space in which He-strong stars are known to exist has doubled in terms of rotational velocity.Comment: 6 pages, 5 figures, 1 Table. Accepted for publication in MNRAS Letter

Magnetization process from Chern-Simons theory and its application to SrCu2(BO3)2

In two-dimensional systems, it is possible transmute bosons into fermions by use of a Chern-Simons gauge field. Such a mapping is used to compute magnetization processes of two-dimensional magnets. The calculation of the magnetization curve then involves the structure of the Hofstadter problem for the lattice under consideration. Certain features of the Hofstadter butterfly are shown to imply the appearance of magnetization plateaus. While not always successfull, this approach leads to interesting results when applied to the 2D AF magnet SrCu2(BO3)2.Comment: 10 pages, 7 figures, Proceedings of the 16th Nishinomiya-Yukawa Memorial Symposium, Nishinomiya, Japan, Nov. 200

Three-dimensional simulations of non-stationary accretion by remnant black holes of compact object mergers

(abridged) Three-dimensional hydrodynamic simulations with an Eulerian PPM code are presented for the time-dependent evolution of accretion tori around nonrotating and rotating stellar-mass black holes (BHs), using a pseudo-Newtonian gravitational potential to approximate the effects of general relativity. The initial configurations are assumed to be remnants of binary neutron star (NS) or NS+BH mergers and consist of a 4 solar mass BH with varied spin, girded by a torus with a mass between 0.01 and 0.2 solar masses. The evolution of tori without and with physical shear viscosity is simulated, using a realistic equation of state and following the energy loss and lepton number change due to neutrino emission by a neutrino-trapping scheme. The time-dependent efficiency of converting rest-mass energy to neutrinos is found to reach 10 percent, the efficiency of converting neutrino energy into a pair-photon fireball by neutrino annihilation can reach several percent. The rate of the latter process declines with time much less steeply than the total neutrino luminosity, because the ongoing protonization of the torus ensures a rather stable product of neutrino and antineutrino luminosities. The neutrino emission increases steeply with higher viscosity, larger torus mass, and larger BH spin in corotation with the torus. For rotation rates as expected for post-merger BHs (a > 0.5) and reasonable values of the alpha viscosity (alpha ~ 0.1), the considered tori release sufficient energy in neutrinos to account for the energetics of the well-localized short gamma-ray bursts recently detected by Hete and Swift, if collimation is invoked as predicted by hydrodynamic jet simulations.Comment: 23 pages, 15 figures (high resolution available upon request), accepted by Astron. Astrophys. Significantly shortened with respect to first versio