10,697 research outputs found
Extragalactic and galactic gamma-rays and neutrinos from annihilating dark matter
We describe cosmic gamma-ray and neutrino signals of dark matter
annihilation, explaining how the complementarity of these signals provides
additional information that, if observable, can enlighten the particle nature
of dark matter. This is discussed in the context of exploiting the separate
galactic and extragalactic components of the signal, using the spherical halo
model distribution of dark matter. We motivate the discussion with
supersymmetric extensions of the standard model of particle physics. We
consider the minimal supersymmetric standard model (MSSM) where both neutrinos
and gamma-rays are produced from annihilations. We also consider a gauged B-L,
baryon number minus lepton number, extension of the MSSM, where annihilation
can be purely to heavy right-handed neutrinos. We compare the galactic and
extragalactic components of these signals, and conclude that it is not yet
clear which may dominate when looking out of the galactic plane. To answer this
question, we must have an understanding of the contribution of halo
substructure to the annihilation signals. We find that different theories with
indistinguishable gamma-ray signals can be distinguished in the neutrino
signal. Gamma-ray annihilation signals are difficult to observe from the
galactic center, due to abundant astrophysical sources; but annihilation
neutrinos from there would not be so hidden, if they can be observed over the
atmospheric neutrinos produced by cosmic rays.Comment: 15 pages, 11 figure
Does responsibility affect the public valuation of health care interventions? A relative valuation approach to health care safety
This article is available open access through the publisher’s website at the link below. Copyright © 2012, International Society for Pharmacoeconomics and
Outcomes Research (ISPOR).Objective - Health services often spend more on safety interventions than seems cost-effective. This study investigates whether the public value safety-related health care improvements more highly than the same improvements in contexts where the health care system is not responsible.
Method - An online survey was conducted to elicit the relative importance placed on preventing harms caused by 1) health care (hospital-acquired infections, drug administration errors, injuries to health care staff), 2) individuals (personal lifestyle choices, sports-related injuries), and 3) nature (genetic disorders). Direct valuations were obtained from members of the public by using a person trade-off or “matching” method. Participants were asked to choose between two preventative interventions of equal cost and equal health benefit per person for the same number of people, but differing in causation. If participants indicated a preference, their strength of preference was measured by using person trade-off.
Results - Responses were obtained from 1030 people, reflecting the sociodemographic mix of the UK population. Participants valued interventions preventing hospital-acquired infections (1.31) more highly than genetic disorders (1.0), although drug errors were valued similarly to genetic disorders (1.07), and interventions to prevent injury to health care staff were given less weight than genetic disorders (0.71). Less weight was also given to interventions related to lifestyle (0.65) and sports injuries (0.41).
Conclusion - Our results suggest that people do not attach a simple fixed premium to “safety-related” interventions but that preferences depend more subtly on context. The use of the results of such public preference surveys to directly inform policy would therefore be premature.Brunel University
Collection and analysis of NASA clean room air samples
The environment of the HALOE assembly clean room at NASA Langley Research Center is analyzed to determine the background levels of airborne organic compounds. Sampling is accomplished by pumping the clean room air through absorbing cartridges. For volatile organics, cartridges are thermally desorbed and then analyzed by gas chromatography and mass spectrometry, compounds are identified by searching the EPA/NIH data base using an interactive operator INCOS computer search algorithm. For semivolatile organics, cartridges are solvent entracted and concentrated extracts are analyzed by gas chromatography-electron capture detection, compound identification is made by matching gas chromatogram retention times with known standards. The detection limits for the semivolatile organics are; 0.89 ng cu m for dioctylphlhalate (DOP) and 1.6 ng cu m for polychlorinated biphenyls (PCB). The detection limit for volatile organics ranges from 1 to 50 parts per trillion. Only trace quantities of organics are detected, the DOP levels do not exceed 2.5 ng cu m and the PCB levels do not exceed 454 ng cu m
Base heating methodology improvements, volume 1
This document is the final report for NASA MSFC Contract NAS8-38141. The contracted effort had the broad objective of improving the launch vehicles ascent base heating methodology to improve and simplify the determination of that environment for Advanced Launch System (ALS) concepts. It was pursued as an Advanced Development Plan (ADP) for the Joint DoD/NASA ALS program office with project management assigned to NASA/MSFC. The original study was to be completed in 26 months beginning Sep. 1989. Because of several program changes and emphasis on evolving launch vehicle concepts, the period of performance was extended to the current completion date of Nov. 1992. A computer code incorporating the methodology improvements into a quick prediction tool was developed and is operational for basic configuration and propulsion concepts. The code and its users guide are also provided as part of the contract documentation. Background information describing the specific objectives, limitations, and goals of the contract is summarized. A brief chronology of the ALS/NLS program history is also presented to provide the reader with an overview of the many variables influencing the development of the code over the past three years
An Investigation of Coach Behaviors, Goal Motives, and Implementation Intentions as Predictors of Well-Being in Sport
The present study aimed to expand upon Smith, Ntoumanis, and Duda’s (2007) research by investigating the influence of coach behaviors and implementation intentions on goal striving in sport. Structural equation modeling analysis with a sample of 108 athletes revealed coach behaviors as predictors of goal motives, which in turn predicted psychological well-being after 8 weeks. Supplementary regression analyses showed no interaction between autonomous goal motives and implementation intentions; however, a synergistic effect was identified for controlled goal motives such that controlled motives furnished with implementation intentions resulted in lower well-being than controlled motives alone. In further analyses, the motives underlying an implementation intention were found to mediate the paths from goal motives to well-being. The findings are discussed in terms of the roles played by goal motives, implementation intentions, and implementation intention motives during goal striving
Universal Probability Distribution for the Wave Function of a Quantum System Entangled with Its Environment
A quantum system (with Hilbert space ) entangled with its
environment (with Hilbert space ) is usually not attributed a
wave function but only a reduced density matrix . Nevertheless, there
is a precise way of attributing to it a random wave function , called
its conditional wave function, whose probability distribution depends
on the entangled wave function in
the Hilbert space of system and environment together. It also depends on a
choice of orthonormal basis of but in relevant cases, as we
show, not very much. We prove several universality (or typicality) results
about , e.g., that if the environment is sufficiently large then for
every orthonormal basis of , most entangled states with
given reduced density matrix are such that is close to one of
the so-called GAP (Gaussian adjusted projected) measures, . We
also show that, for most entangled states from a microcanonical subspace
(spanned by the eigenvectors of the Hamiltonian with energies in a narrow
interval ) and most orthonormal bases of ,
is close to with the
normalized projection to the microcanonical subspace. In particular, if the
coupling between the system and the environment is weak, then is close
to with the canonical density matrix on
at inverse temperature . This provides the
mathematical justification of our claim in [J. Statist. Phys. 125:1193 (2006),
http://arxiv.org/abs/quant-ph/0309021] that measures describe the thermal
equilibrium distribution of the wave function.Comment: 27 pages LaTeX, no figures; v2 major revision with simpler proof
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