23,154 research outputs found

    Cosmic-ray transport in the galactic magnetosphere

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    It is advantageous to regard cosmic rays as the constitutent particles of the Galactic radiation belts and cosmic ray energization as a consequence of inward radial diffusion in the quasi-dipolar Galactic magnetosphere. This process occurs in addition to Fermi acceleration. The purpose of this work is to explore a magnetospheric explanation for the elevation of Galactic charged particles to cosmic ray energies. The magnetosphere that is of interest in this context is not a planetary magnetosphere but a galactic magnetosphere entirely analogous to those inferred from radio observations of distant galaxies. It is the magnetosphere of the Milky Way. Cosmic rays are (by this interpretation) the charged particles that constitute the radiation belts of the Galactic magnetosphere. Thus, the mechanism by which charged particles attain cosmic-ray energies is presumable the mechanism by which radiation-belt particles attain high energies in more familiar magnetosphere, i.e., the radial diffusion associated with magnetic disturbances that contain spectral power resonant with the azimuthal drift of the particles

    Kinetic induced phase transition

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    An Ising model with local Glauber dynamics is studied under the influence of additional kinetic restrictions for the spin-flip rates depending on the orientation of neighboring spins. Even when the static interaction between the spins is completely eliminated and only an external field is taken into account the system offers a phase transition at a finite value of the applied field. The transition is realized due to a competition between the activation processes driven by the field and the dynamical rules for the spin-flips. The result is based on a master equation approach in a quantum formulation.Comment: 13 page

    On the Glauber model in a quantum representation

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    The Glauber model is reconsidered based on a quantum formulation of the Master equation. Unlike the conventional approach the temperature and the Ising energy are included from the beginning by introducing a Heisenberg-like picture of the second quantized operators. This method enables us to get an exact expression for the transition rate of a single flip-process wi(σi)w_i(\sigma_i) which is in accordance with the principle of detailed balance. The transition rate differs significantly from the conventional one due to Glauber in the low temperature regime. Here the behavior is controlled by the Ising energy and not by the microscopic time scale.Comment: 8 page

    Acute pulmonary pathology and sudden death in rats following the intravenous administration of the plasticizer, DI (2-ethylhexyl) phthalate, solubilized with Tween surfactants

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    Intravenous administration of 200-300 mg/kg of di(2-ethylhexyl)phthalate (DEHP) solubilized in aqueous solutions of several Tween surfactants caused respiratory distress in rats. There was a dose-dependent lethality with death generally occurring within 90 minutes after injection. The lungs from DEHP:Tween treated animals were enlarged, generally darkened, and in some cases showed hemorrhagic congestion. Neither the overt symptoms nor the morphologic alterations resulting from DEHP:Tween administration could be reproduced by intravenous administration of aqueous Tween solutions alone. The absence of pulmonary abnormalities following the intravenous administration of DEHP as an aqueous emulsion given either alone or even as soon as 2 minutes after pretreatment with Tween 80, suggests that the specific in vivo interaction between DEHP and Tween surfactants depends on the prior formation of water-soluble micelles of DEHP

    Surveys of Galaxy Clusters with the Sunyaev Zel'dovich Effect

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    We have created mock Sunyaev-Zel'dovich effect (SZE) surveys of galaxy clusters using high resolution N-body simulations. To the pure surveys we add `noise' contributions appropriate to instrument and primary CMB anisotropies. Applying various cluster finding strategies to these mock surveys we generate catalogues which can be compared to the known positions and masses of the clusters in the simulations. We thus show that the completeness and efficiency that can be achieved depend strongly on the frequency coverage, noise and beam characteristics of the instruments, as well as on the candidate threshold. We study the effects of matched filtering techniques on completeness, and bias. We suggest a gentler filtering method than matched filtering in single frequency analyses. We summarize the complications that arise when analyzing the SZE signal at a single frequency, and assess the limitations of such an analysis. Our results suggest that some sophistication is required when searching for `clusters' within an SZE map.Comment: 8 pages, 7 figure

    Polarization fine-structure and enhanced single-photon emission of self-assembled lateral InGaAs quantum dot molecules embedded in a planar micro-cavity

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    Single lateral InGaAs quantum dot molecules have been embedded in a planar micro-cavity in order to increase the luminescence extraction efficiency. Using a combination of metal-organic vapor phase and molecular beam epitaxy samples could be produced that exhibit a 30 times enhanced single-photon emission rate. We also show that the single-photon emission is fully switchable between two different molecular excitonic recombination energies by applying a lateral electric field. Furthermore, the presence of a polarization fine-structure splitting of the molecular neutral excitonic states is reported which leads to two polarization-split classically correlated biexciton exciton cascades. The fine-structure splitting is found to be on the order of 10 micro-eV.Comment: 14 pages, 4 figures; the following article has been submitted to Journal of Applied Physics (29th ICPS - invited paper); after it is published, it will be found at http://jap.aip.org

    Coreness of Cooperative Games with Truncated Submodular Profit Functions

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    Coreness represents solution concepts related to core in cooperative games, which captures the stability of players. Motivated by the scale effect in social networks, economics and other scenario, we study the coreness of cooperative game with truncated submodular profit functions. Specifically, the profit function f(⋅)f(\cdot) is defined by a truncation of a submodular function σ(⋅)\sigma(\cdot): f(⋅)=σ(⋅)f(\cdot)=\sigma(\cdot) if σ(⋅)≥η\sigma(\cdot)\geq\eta and f(⋅)=0f(\cdot)=0 otherwise, where η\eta is a given threshold. In this paper, we study the core and three core-related concepts of truncated submodular profit cooperative game. We first prove that whether core is empty can be decided in polynomial time and an allocation in core also can be found in polynomial time when core is not empty. When core is empty, we show hardness results and approximation algorithms for computing other core-related concepts including relative least-core value, absolute least-core value and least average dissatisfaction value

    The Herschel Space Observatory view of dust in M81

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    We use Herschel Space Observatory data to place observational constraints on the peak and Rayleigh-Jeans slope of dust emission observed at 70−500 μm in the nearby spiral galaxy M81. We find that the ratios of wave bands between 160 and 500 μm are primarily dependent on radius but that the ratio of 70 to 160 μm emission shows no clear dependence on surface brightness or radius. These results along with analyses of the spectral energy distributions imply that the 160−500 μm emission traces 15−30 K dust heated by evolved stars in the bulge and disc whereas the 70 μm emission includes dust heated by the active galactic nucleus and young stars in star forming regions

    Evaluation of pharmaceutical concerns in Germany: frequency and potential reasons.

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    BACKGROUND: Generic substitution can have unintended consequences. In Germany, brand name to generic or generic to generic switching is mainly driven by rebate contracts. Frequent switching may raise concerns about bio- and therapeutic equivalence. Expected patient confusion may result in compromised medication adherence or new onset of other drug-related problems. Since 2008, pharmacists are allowed to deviate from rebate contracts by denying substitution due to pharmaceutical concerns on an individual basis. OBJECTIVES: To explore the frequency of documented pharmaceutical concerns in Germany between July 2011 and December 2013 and to identify the medicines most frequently related to pharmaceutical concerns in 2013. METHODS: We analyzed documented pharmaceutical concerns in all prescribed drugs at the expense of any statutory health insurance company requiring pharmacies' generic substitution according to rebate contracts. RESULTS: Since July 2011, the frequency of documented pharmaceutical concerns in relation to prescribed drug products with rebate contracts requiring substitution increased consistently and doubled between July 2011 and July 2013. Overall in 2013, the trend of the two previous years continued and reached approximately 1.5%. The most affected drugs/drug classes were thyroid hormones (in particular combinations with iodide; 15.9%) followed by ondansetron (12.5%), and levothyroxine (11.3%). For all drugs/drug classes under investigation, product-, patient- or disease-related aspects could be identified which are potential reasons to deny substitution and to document pharmaceutical concerns. CONCLUSIONS: Although there is no electronic recording of the specific reasons for pharmaceutical concerns in claims data, our analyses support the assumption that pharmacists make use of this instrument based on individual clinical decisions and as required by contract. Pharmaceutical concerns are, therefore, an important instrument for pharmacies to refuse generic substitution. They are considered to prevent compromised medication safety and to assure pharmacotherapy effectiveness in a generic substitution environment driven by low drug prizes above all
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