Mechanism of temperature dependence of the magnetic anisotropy energy in ultrathin Cobalt and Nickel films

Temperature dependent FMR-measurements of Ni and Co films are analysed using a microscopic theory for ultrathin metallic systems. The mechanism governing the temperature dependence of the magnetic anisotropy energy is identified and discussed. It is reduced with increasing temperature. This behavior is found to be solely caused by magnon excitations.Comment: 3 pages, 4 figures III Joint European Magnetic Symposia, San Sebastian, Spai

Optimization of a neutrino factory oscillation experiment

We discuss the optimization of a neutrino factory experiment for neutrino oscillation physics in terms of muon energy, baselines, and oscillation channels (gold, silver, platinum). In addition, we study the impact and requirements for detector technology improvements, and we compare the results to beta beams. We find that the optimized neutrino factory has two baselines, one at about 3000 to 5000km, the other at about 7500km (``magic'' baseline). The threshold and energy resolution of the golden channel detector have the most promising optimization potential. This, in turn, could be used to lower the muon energy from about 50GeV to about 20GeV. Furthermore, the inclusion of electron neutrino appearance with charge identification (platinum channel) could help for large values of \sin^2 2 \theta_{13}. Though tau neutrino appearance with charge identification (silver channel) helps, in principle, to resolve degeneracies for intermediate \sin^2 2 \theta_{13}, we find that alternative strategies may be more feasible in this parameter range. As far as matter density uncertainties are concerned, we demonstrate that their impact can be reduced by the combination of different baselines and channels. Finally, in comparison to beta beams and other alternative technologies, we clearly can establish a superior performance for a neutrino factory in the case \sin^2 2 \theta_{13} < 0.01.Comment: 51 pages, 25 figures, 6 tables, references corrected, final version to appear in Phys. Rev.

keV sterile neutrino dark matter in gauge extensions of the standard model

It is known that a keV scale sterile neutrino is a good warm dark matter candidate. We study how this possibility could be realized in the context of gauge extensions of the standard model. The na\"ive expectation leads to large thermal overproduction of sterile neutrinos in this setup. However, we find that it is possible to use out-of-equilibrium decay of the other right-handed neutrinos of the model to dilute the present density of the keV sterile neutrinos and achieve the observed dark matter density. We present the universal requirements that should be satisfied by the gauge extensions of the standard model, containing right-handed neutrinos, to be viable models of warm dark matter, and provide a simple example in the context of the left-right symmetric model.Comment: RevTex, 13 pages, 5 figures; journal version (corrected typos

Spin wave excitations: The main source of the temperature dependence of Interlayer exchange coupling in nanostructures

Quantum mechanical calculations based on an extended Heisenberg model are compared with ferromagnetic resonance (FMR) experiments on prototype trilayer systems Ni_7/Cu_n/Co_2/Cu(001) in order to determine and separate for the first time quantitatively the sources of the temperature dependence of interlayer exchange coupling. Magnon excitations are responsible for about 75% of the reduction of the coupling strength from zero to room temperature. The remaining 25% are due to temperature effects in the effective quantum well and the spacer/magnet interfaces.Comment: accepted for publication in PR

On the coupling of massless particles to scalar fields

It is investigated if massless particles can couple to scalar fields in a special relativistic theory with classical particles. The only possible obvious theory which is invariant under Lorentz transformations and reparametrization of the affine parameter leads to trivial trajectories (straight lines) for the massless case, and also the investigation of the massless limit of the massive theory shows that there is no influence of the scalar field on the limiting trajectories. On the other hand, in contrast to this result, it is shown that massive particles are influenced by the scalar field in this theory even in the ultra-relativistic limit.Comment: 9 pages, no figures, uses titlepage.sty, LaTeX 2.09 file, submitted to International Journal of Theoretical Physic

Microscopic and Macroscopic Effects in the Decoherence of Neutrino Oscillations

We present a generic structure (the layer structure) for decoherence effectsin neutrino oscillations, which includes decoherence from quantum mechanicaland classical uncertainties. The calculation is done by combining the conceptof open quantum system and quantum field theory, forming a structure composedof phase spaces from microscopic to macroscopic level. Having information lossat different levels, quantum mechanical uncertainties parameterize decoherenceby an intrinsic mass eigenstate separation effect, while decoherence forclassical uncertainties is typically dominated by a statistical averagingeffect. With the help of the layer structure, we classify the former as statedecoherence (SD) and the latter as phase decoherence (PD), then furtherconclude that both SD and PD result from phase wash-out effects of differentphase structures on different layers. Such effects admit for simple numericalcalculations of decoherence for a given width and shape of uncertainties. Whileour structure is generic, so are the uncertainties, nonetheless, a few notableones are: the wavepacket size of the external particles, the effectiveinteraction volume at production and detection, the energy reconstruction modeland the neutrino production profile. Furthermore, we estimate the experimentalsensitivities for SD and PD parameterized by the uncertainty parameters, forreactor neutrinos and decay-at-rest neutrinos, using a traditional ratemeasuring method and a novel phase measuring method.<br

Lessons from the Draft Horse Industry in East Texas

The purpose of the study reported here was to determine and understand the variables responsible for the revival of the draft horse industry in East Texas. The draft horse industry can provide viable employment for rural entrepreneurs. The authors suggest universities and Extension rethink their traditional roles of supporting and providing resources for rural entrepreneurs engaged in agricultural enterprises that utilize relic technologies

Ethische Kompetenz im Rettungsdienst: Ausbildung professioneller Helfer - Ergebnisse einer Interviewstudie in Basel

Zusammenfassung: Fragestellung: Ziel der Studie war es, die ethischen Dimensionen von Reanimationsentscheidungen im Rettungsdienst zu untersuchen. Methode: Ein qualitatives Studiendesign wurde entwickelt, um ethische Entscheidungskriterien, persönliche Wertvorstellungen und Bedarf an Aus- und Weiterbildung zu erfragen. Mit Rettungsdienstmitarbeitern in Basel wurden 30 strukturierte Interviews geführt und nach der qualitativen Inhaltsanalyse ausgewertet. Ergebnisse: Notärzte und Rettungssanitäter beziehen eine Vielzahl ethischer Überlegungen in ihre Entscheidungen mit ein. Die Mehrheit äußerte Interesse an ethischer Schulung oder forderte sogar eine stärkere Verankerung ethischer Inhalte in Aus- und Weiterbildung. Schlussfolgerung: Konzepte für die Vermittlung medizinischer Ethik sollten den Bedürfnissen professioneller Helfer und den besonderen Gegebenheiten des Rettungsdienstes Rechnung trage