6,969 research outputs found
THE END OF SUPPLY CONTROLS: THE ECONOMIC EFFECTS OF RECENT CHANGE IN FEDERAL PEANUT POLICY
The paper analyzes recent changes in U.S. peanut policy as enacted in the 2002 Farm Security Act. A model representing the impact of the 2002 farm bill on the domestic and foreign prices of edible peanuts is constructed and the gains and losses to peanut producing states are measured.Agricultural and Food Policy,
The Large-Scale Distribution and Motions of Older Stars in Orion
We review the current knowledge of the population of `older' stars in the
Orion OB1 association, specifically those in subgroups 1a and 1b. We briefly
outline the history of the subject and then continue with a summary of the
present state of knowledge of the early-type stars in Orion OB1. New results
from the Hipparcos parallaxes and proper motions will be presented. The main
result is that subgroup 1a is located at about 330 pc from the Sun, much closer
than the previously determined distance, and about 100 pc distant from the
other subgroups of the association and the Orion molecular clouds.
Unfortunately, due to the unfavorable kinematics of the association with
respect to the Galactic background, Hipparcos proper motions do not allow a
clear kinematic separation of the association from the field. For this purpose
accurate and homogeneous radial velocities are needed. Traditionally, the
massive O and B stars have received most of the attention in the studies of OB
associations. However, we will present results showing that significant numbers
of low-mass stars are associated with Orion OB1. Unbiased, optically complete,
spectroscopic and photometric surveys of areas within subgroups 1a and 1b have
the potential to determine the complete low-mass stellar population, down to
the brown dwarf limit. This will provide much insight into the overall initial
mass function and studies of the kinematics of the low-mass stars will yield
insights into the dispersal of the association.Comment: To appear in The Orion Complex Revisited, eds. M. J. McCaughrean & A.
Burkert (San Francisco, ASP), gzipped tar-file, 22 pages 7 EPS-figures, LaTeX
using paspconf.sty and psfig.tex. Wrongly quoted errors on the average
parallaxes of the Orion OB1 subgroups were corrected (Section 4
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A Systematic Review of Comparative Efficacy of Treatments and Controls for Depression
Background: Although previous meta-analyses have examined effects of antidepressants, psychotherapy, and alternative therapies for depression, the efficacy of these treatments alone and in combination has not been systematically compared. We hypothesized that the differences between approved depression treatments and controls would be small. Methods and Findings: The authors first reviewed data from Food and Drug Administration Summary Basis of Approval reports of 62 pivotal antidepressant trials consisting of data from 13,802 depressed patients. This was followed by a systematic review of data from 115 published trials evaluating efficacy of psychotherapies and alternative therapies for depression. The published depression trials consisted of 10,310 depressed patients. We assessed the percentage symptom reduction experienced by the patients based on treatment assignment. Overall, antidepressants led to greater symptom reduction compared to placebo among both unpublished FDA data and published trials (F = 38.5, df = 239, p<0.001). In the published trials we noted that the magnitude of symptom reduction with active depression treatments compared to controls was significantly larger when raters evaluating treatment effects were un-blinded compared to the trials with blinded raters (F = 2.17, df = 313, p<0.05). In the blinded trials, the combination of antidepressants and psychotherapy provided a slight advantage over antidepressants (p = 0.027) and psychotherapy (p = 0.022) alone. The magnitude of symptom reduction was greater with psychotherapies compared to placebo (p = 0.019), treatment-as-usual (p = 0.012) and waiting-list (p<0.001). Differences were not seen with psychotherapy compared to antidepressants, alternative therapies or active intervention controls. Conclusions: In conclusion, the combination of psychotherapy and antidepressants for depression may provide a slight advantage whereas antidepressants alone and psychotherapy alone are not significantly different from alternative therapies or active intervention controls. These data suggest that type of treatment offered is less important than getting depressed patients involved in an active therapeutic program. Future research should consider whether certain patient profiles might justify a specific treatment modality
XMM-Newton Finds That SAX J1750.8-2900 May Harbor the Hottest, Most Luminous Known Neutron Star
We have performed the first sensitive X-ray observation of the low-mass X-ray
binary SAX J1750.8-2900 in quiescence with XMM-Newton. The spectrum was fit to
both a classical black body model, and a non-magnetized, pure hydrogen neutron
star atmosphere model. A power law component was added to these models, but we
found that it was not required by the fits. The distance to SAX J1750.8-2900 is
known to be D = 6.79 kpc from a previous analysis of photospheric radius
expansion bursts. This distance implies a bolometric luminosity (as given by
the NS atmosphere model) of (1.05 +/- 0.12) x 10^34 (D/6.79 kpc)^2 erg s^-1,
which is the highest known luminosity for a NS LMXB in quiescence. One simple
explanation for this surprising result could be that the crust and core of the
NS were not in thermal equilibrium during the observation. We argue that this
was likely not the case, and that the core temperature of the NS in SAX
J1750.8-2900 is unusually high
Research & Technology Report Goddard Space Flight Center
The main theme of this edition of the annual Research and Technology Report is Mission Operations and Data Systems. Shifting from centralized to distributed mission operations, and from human interactive operations to highly automated operations is reported. The following aspects are addressed: Mission planning and operations; TDRSS, Positioning Systems, and orbit determination; hardware and software associated with Ground System and Networks; data processing and analysis; and World Wide Web. Flight projects are described along with the achievements in space sciences and earth sciences. Spacecraft subsystems, cryogenic developments, and new tools and capabilities are also discussed
The Spectral Energy Distribution of CO lines in M82
We present an analysis of the excitation conditions of the molecular gas in
the streamers and the outflow of M82 based on observations obtained at the IRAM
30m telescope. Our analysis of J=1-0 and J=2-1 transitions of CO and 13CO and
the CO(3-2) line in 13 regions outside the central starburst disk shows that
the gas density within the streamer/outflow system is about an orderof
magnitude lower (n(H2) ~ 10^3 cm^-3) than in the central molecular disk. We
have used an LVG model and data from the literature to constrain the flux
density in each CO transition (the `CO line SED') arising from the
streamer/outflow system and the central starburst disk itself. Globally, we
find that the CO flux density up to the J=3-2 line is dominated by the diffuse
outer regions while lines above the J=5-4 transition are almost exclusively
emitted by the central starburst disk. We compare the CO line SED of M82 to CO
observations of galaxies at high redshift and suggest that small high-J/low-J
CO flux density ratios (observed in some of these sources) are not necessarily
caused by a different excitation of the central molecular gas concentration,
but may result from an additional, more extended and diffuse gas reservoir
around these systems, reminiscent of the situation in M82.Comment: 12 pages, 7 figures, accepted by A&
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