5,153 research outputs found
FULL-TIME VS. PART-TIME: AN EVALUATION OF THE COMPETITIVENESS OF RESERVE OFFICERS BY COMMISSIONING SOURCE
This research examines whether the quality of officers commissioned under the Reserve Officer Commissioning Program (ROCP) differs from those officers who entered the reserve component with a prior period of active service. As the ROCP matures, more officers serve in the Selected Marine Corps Reserve (SMCR) without serving their initial service obligation in the active component. Officers commissioned via the ROCP will not have the same saturation of active service. I seek to determine whether the concept that active component service improves an officer’s performance is true. Using measures of performance and retention, I analyze whether there is a difference between ROCP officers when compared to reserve officers with prior active service. The results show that while certain variables contribute to a statistically significant difference in relative values between the two groups of officers, the value of these differences is too small to be economically meaningful. Ultimately, I find that the performance of ROCP officers and officers with prior active service is similar.Major, United States Marine Corps ReserveApproved for public release. Distribution is unlimited
A Strong X-Ray Burst from the Low Mass X-Ray Binary EXO0748-676
We have observed an unusually strong X-ray burst as a part of our regular
eclipse timing observations of the low mass binary system EXO0748-676. The
burst peak flux was 5.2x10^-8 ergs cm^-2 s^-1, approximately five times the
normal peak X-ray burst flux observed from this source by RXTE. Spectral fits
to the data strongly suggest that photospheric radius expansion occurred during
the burst. In this Letter we examine the properties of this X-ray burst, which
is the first example of a radius expansion burst from EXO0748-676 observed by
RXTE. We find no evidence for coherent burst oscillations. Assuming that the
peak burst luminosity is the Eddington luminosity for a 1.4 solar mass neutron
star we derive a distance to EXO0748-676 of 7.7 kpc for a helium-dominated
burst photosphere and 5.9 kpc for a hydrogen-dominated burst photosphere.Comment: 15 pages including 2 figures and 1 table. Accepted for publication in
the Astrophysical Journa
An Empirical Analysis of Cigarette Addiction
We use a framework suggested by a model of rational addiction to analyze empirically the demand for cigarettes. The data consist of per capita cigarettes sales (in packs) annually by state for the period 1955 through 1985. The empirical results provide support for the implications of a rational addiction model that cross price effects are negative (consumption in different periods are complements), that long-run price responses exceed short-run responses, and that permanent price effects exceed temporary price effects. A 10 percent permanent increase in the price of cigarettes reduces current consumption by 4 percent in the short run and by 7.5 percent in the long run. In contrast, a 10 percent increase in the price for only one period decreases consumption by only 3 percent. In addition, a one period price increase of 10 percent reduces consumption in the previous period by approximately .7 percent and consumption in the subsequent period by 1.5 percent. These estimates illustrate the importance of the intertemporal linkages in cigarette demand implied by rational addictive behavior.
The Economic Theory of Illegal Goods: The Case of Drugs
This paper concentrates on both the positive and normative effects of punishments that enforce laws to make production and consumption of particular goods illegal, with illegal drugs as the main example. Optimal public expenditures on apprehension and conviction of illegal suppliers obviously depend on the extent of the difference between the social and private value of consumption of illegal goods, but they also depend crucially on the elasticity of demand for these goods. In particular, when demand is inelastic, it does not pay to enforce any prohibition unless the social value is negative and not merely less than the private value. We also compare outputs and prices when a good is legal and taxed with outputs and prices when the good is illegal. We show that a monetary tax on a legal good could cause a greater reduction in output and increase in price than would optimal enforcement, even recognizing that producers may want to go underground to try to avoid a monetary tax. This means that fighting a war on drugs by legalizing drug use and taxing consumption may be more effective than continuing to prohibit the legal use of drugs.
Economics of Marital Instability
This paper focuses on the causes of divorce. Section I developsa theoretical analysis of marital dissolution incorporating uncertaintyabout the outcomes of marital decisions into a framework of utilitymaximization and the marriage market. Section II explores the implica-tions of the theoretical analysis with cross-sectional data,primarilythe 1967 Survey of Economic Opportunity and the Terman sample. Therelevance of both the theoretical and empirical analyses in explainingthe recent acceleration in the U.S. divorce rate is discussed.
Discovery of a Radio-loud/Radio-quiet Binary Quasar
We report the discovery of a small separation quasar pair (z=0.586, O=18.4,
19.2, sep. = 2.3 arcsec) associated with the radio source FIRST
J164311.3+315618 (S_1400 = 120 mJy). The spectrum of the brighter quasar (A)
has a much stronger narrow emission-line spectrum than the other (B), and also
stronger Balmer lines relative to the continuum. The continuum ratio of the
spectra is flat in the blue at about 2.1, but falls to 1.5 at longer
wavelengths. A K' image shows two unresolved sources with a flux ratio of 1.3.
The different colors appear to result from the contribution of the host galaxy
of B, which is evident from Ca II and high-order Balmer absorption lines
indicative of a substantial young stellar population. New 3.6 cm VLA
observations show that the compact radio source is coincident with quasar A (B
is only marginally detected). We rule out the lensing hypothesis because the
optical flux ratio is A/B = 1.2 to 2, while the radio flux ratio is A/B > 40,
and conclude that this system is a binary. Moreover, the radio-loud quasar is a
compact steep spectrum source. FIRST J164311.3+315618A, B is the lowest
redshift and smallest separation binary quasar yet identified.Comment: 8 pages, 3 figures, to appear in Astrophysical Journal Letter
Is the Compact Source at the Center of Cas A Pulsed?
A 50 ksec observation of the Supernova Remnant Cas A was taken using the
Chandra X-Ray Observatory High Resolution Camera (HRC) to search for periodic
signals from the compact source located near the center. Using the HRC-S in
imaging mode, problems with correctly assigning times to events were overcome,
allowing the period search to be extended to higher frequencies than possible
with previous observations. In an extensive analysis of the HRC data, several
possible candidate signals are found using various algorithms, including
advanced techniques developed by Ransom to search for low significance periodic
signals. Of the candidate periods, none is at a high enough confidence level to
be particularly favored over the rest. When combined with other information,
however (e.g., spectra, total energetics, and the historical age of the
remnant), a 12 ms candidate period seems to be more physically plausible than
the others, and we use it for illustrative purposes in discussing the possible
properties of a putative neutron star in the remnant. We emphasize that this is
not necessarily the true period, and that a follow-up observation, scheduled
for the fall of 2001, is required.
A 50 ksec Advanced CCD Imaging Spectrometer (ACIS) observation was taken, and
analysis of these data for the central object shows that the spectrum is
consistent with several forms, and that the emitted X-ray luminosity in the 0.1
-10 keV band is 10^{33}-10^{35}erg cm^{-2}sec^{-1} depending on the spectral
model and the interstellar absorption along the line of sight to the source.Comment: 14 pages, 3 figures Submitted to ApJ 2001 June 2
The Importance of Incorporating Landscape Change for Predictions of Climate-Induced Plant Phenological Shifts
Warming in the high Arctic is occurring at the fastest rate on the planet, raising concerns over how this global change driver will influence plant community composition, the timing of vegetation phenological events, and the wildlife that rely on them. In this region, as much as 50% of near-surface permafrost is composed of thermally sensitive ground ice that when melted produces substantial changes in topography and microbiome conditions. We take advantage of natural variations in permafrost melt to conduct a space-for-time study on Ellesmere Island in northern Canada. We demonstrate that phenological timing can be delayed in thermokarst areas when compared to stable ground, and that this change is a function of shifting species composition in these vegetation communities as well as delayed timing within species. These findings suggest that a warming climate could result in an overall broadening of blooming and leafing windows at the landscape level when these delayed timings are taken into consideration with the projected advance of phenological timings in ice-poor areas. We emphasize that the impacts of geomorphic processes on key phenological drivers are essential for enhancing our understanding of community response to climate warming in the high Arctic, with implications for ecosystem functioning and trophic interactions.ISSN:1664-462
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