13,072 research outputs found
GALPROP WebRun: an internet-based service for calculating galactic cosmic ray propagation and associated photon emissions
GALPROP is a numerical code for calculating the galactic propagation of
relativistic charged particles and the diffuse emissions produced during their
propagation. The code incorporates as much realistic astrophysical input as
possible together with latest theoretical developments and has become a de
facto standard in astrophysics of cosmic rays. We present GALPROP WebRun, a
service to the scientific community enabling easy use of the freely available
GALPROP code via web browsers. In addition, we introduce the latest GALPROP
version 54, available through this service.Comment: Accepted for publication in Computer Physics Communications. Version
2 includes improvements suggested by the referee. Metadata completed in
version 3 (no changes to the manuscript
Surface circulation in the Great Lakes as observed by LANDSAT-1 August 1972 - December 1973: Southern Lake Michigan
The surface current circulation patterns of southern Lake Michigan were charted for all cardinal and subcardinal wind directions, employing LANDSAT-1 observations of the distribution of natural tracing material borne in the surface waters. These colorants consist chiefly of river discharges composed of suspended sediments, pollutants, and algae; extensive chemical precipitations proved valuable for areas farther from shore. Comparison of the satellite-derived surface current charts with previous theoretical and empirical studies shows good agreement
Propagation of cosmic rays: nuclear physics in cosmic-ray studies
The nuclei fraction in cosmic rays (CR) far exceeds the fraction of other CR
species, such as antiprotons, electrons, and positrons. Thus the majority of
information obtained from CR studies is based on interpretation of isotopic
abundances using CR propagation models where the nuclear data and isotopic
production cross sections in p- and alpha-induced reactions are the key
elements. This paper presents an introduction to the astrophysics of CR and
diffuse gamma rays and discusses some of the puzzles that have emerged recently
due to more precise data and improved propagation models. Merging with
cosmology and particle physics, astrophysics of CR has become a very dynamic
field with a large potential of breakthrough and discoveries in the near
future. Exploiting the data collected by the CR experiments to the fullest
requires accurate nuclear cross sections.Comment: 6 pages, 13 figures, aip style files. Invited review talk at the Int.
Conf. on Nuclear Data-2004 (Santa Fe, Sep. 26 - Oct. 1, 2004). To appear in
AIP Conf. Pro
Challenging cosmic ray propagation with antiprotons. Evidence for a "fresh" nuclei component?
Recent measurements of the cosmic ray (CR) antiproton flux have been shown to
challenge existing CR propagation models. It was shown that the reacceleration
models designed to match secondary to primary nuclei ratios (e.g.,
boron/carbon) produce too few antiprotons. Matching both the secondary to
primary nuclei ratio and the antiproton flux requires artificial breaks in the
diffusion coefficient and the primary injection spectrum suggesting the need
for other approaches.
In the present paper we discuss one possibility to overcome these
difficulties. Using the measured antiproton flux AND B/C ratio to fix the
diffusion coefficient, we show that the spectra of primary nuclei as measured
in the heliosphere may contain a fresh local "unprocessed" component at low
energies perhaps associated with the Local Bubble, thus decreasing the measured
secondary to primary nuclei ratio. The independent evidence for SN activity in
the solar vicinity in the last few Myr supports this idea. The model reproduces
antiprotons, B/C ratio, and elemental abundances up to Ni (Z<=28). Calculated
isotopic distributions of Be and B are in perfect agreement with CR data. The
abundances of three "radioactive clock" isotopes in CR, 10Be, 26Al, 36Cl, are
all consistent and indicate a halo size z_h~4 kpc based on the most accurate
data taken by the ACE spacecraft.Comment: To be published in The Astrophysical Journal, v.586, 2003 April 1;
final version: 19 pages, 24 ps-figures, emulateapj5.sty (modified),
natbib.sty, aastex.cls. More details can be found at
http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
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Enhancing engagement in evidence-based tobacco cessation treatment for smokers with mental illness: A pilot randomized trial.
ObjectiveTo evaluate the efficacy of a brief telephone-delivered Motivational Interviewing (MI)-based intervention to facilitate engagement in evidence-based cessation treatment for Veterans with mental illness referred to smoking cessation treatment.Methods86 military Veteran smokers with mental illness were recruited from a tobacco cessation consult clinic and randomized to receive either a MI-based treatment engagement intervention (TE; n = 48) or a non-MI assessment and information control (CON; n = 38) condition. Intervention was delivered during a single brief telephone contact. Primary engagement outcomes were 1) attending a treatment session within 30 days and 2) combination treatment (attending session plus using pharmacotherapy). Cessation outcomes included self-reported 24 h cessation attempts and 7 day point abstinence at 3 months post-intervention. Outcomes were assessed at 1 and 3 months post intervention.ResultsOutcome analyses included 85 participants (47 TE, 38 CON) using an intent-to-treat analytic approach. Participants were on average 49.5 (13.4) years old, 88% Male, 59% white, 18% African American and 14% Hispanic/Latino(a). Following intervention delivery TE and CON participants did not differ on likelihood of attending a treatment session during the subsequent 30 days (47% vs 45%, respectively). A significant difference was observed when classified as utilizing combination treatment, 40% of TE versus 18% of CON reported use of smoking cessation medication and behavioral counseling (p = 0.04). No statistical differences were observed for cessation outcomes, although more TE than CON participants reported 7 day point abstinence at 3 months post-intervention (30% vs 18%).ConclusionsThe present pilot study provides initial evidence for the feasibility, acceptability and efficacy of a telephone delivered TE intervention for enhancing engagement in combinationevidence evidence-based treatment in a sample of Veteran smokers with mental illness referred to smoking cessation treatment. Smokers with mental illness typically have greater difficulty stopping smoking than those without mental illness. Increased engagement in combination treatment thus has the potential to increase quit rates and ultimately reduce the burden of tobacco use for this population
Techniques for carrying out radiative transfer calculations for the Martian atmospheric dust
A description is given of the modification of a theory on the reflectance of particulate media so as to apply it to analysis of the infrared spectra obtained by the IRIS instrument on Mariner 9. With the aid of this theory and the optical constants of muscovite mica, quartz, andesite, anorthosite, diopside pyroxenite, and dunite, modeling calculations were made to refine previous estimates of the mineralogical composition of the Martian dust particles. These calculations suggest that a feldspar rich mixture is a very likely composition for the dust particles. The optical constants used for anorthosite and diopside pyroxenite were derived during this program from reflectance measurements. Those for the mica were derived from literature reflectance data. Finally, a computer program was written to invert the measured radiance data so as to obtain the absorption coefficient spectrum which should then be independent of the temperature profile and gaseous component effects
Gamma-Ray Burst Detection with INTEGRAL/SPI
The spectrometer SPI, one of the two main instruments of the INTEGRAL
spacecraft, has strong capabilities in the Field of Gamma-Ray Burst (GRB)
detections. In its 16 degree Field of view (FoV) SPI is able to trigger and to
localize GRBs. With its large anticoincidence shield (ACS) of 512 kg of BGO
crystals SPI is able to detect GRBs quasi omnidirectionally with a very high
sensitivity. The ACS GRB alerts will provide GRB arrival times with high
accuracy but with no or very rough positional information. The expected GRB
detection rate in SPI's FoV will be one per month and for the ACS around 300
per year. At MPE two SPI software contributions to the real-time INTEGRAL
burst-alert system (IBAS) at the INTEGRAL science data centre ISDC have been
developed. The SPI-ACS branch of IBAS will produce burst alerts and
light-curves with 50 ms resolution. It is planned to use ACS burst alerts in
the 3rd interplanetary network. The SPI-FoV branch of IBAS is currently under
development at MPE. The system is using the energy and timing information of
single and multiple events detected by the Germanium-camera of SPI. Using the
imaging algorithm developed at the University of Birmingham the system is
expected to locate strong bursts with an accuracy of better than 1 degree.Comment: 11 pages, 5 figure
Propagation of Light Elements in the Galaxy
The origin and evolution of isotopes of the lightest elements H2, He3, Li,
Be, B in the universe is a key problem in such fields as astrophysics of CR,
Galactic evolution, non-thermal nucleosynthesis, and cosmological studies. One
of the major sources of these species is spallation by CR nuclei in the
interstellar medium. On the other hand, it is the B/C ratio in CR and Be10
abundance which are used to fix the propagation parameters and thus the
spallation rate. We study the production and Galactic propagation of isotopes
of elements Z<6 using the numerical propagation code GALPROP and updated
production cross sections.Comment: 4 pages, 6 ps-figures, tsukuba.sty, to appear in the Proc. 28th
International Cosmic Ray Conference (Tsukuba, Japan 2003). More details can
be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
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