12,466 research outputs found

    Analysis of partial-reflection data from the solar eclipse of 10 Jul. 1972

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    Partial-reflection data collected for the eclipse of July 10, 1972 as well as for July 9 and 11, 1972, are analyzed to determine eclipse effects on D-region electron densities. The partial-reflection experiment was set up to collect data using an on-line PDP-15 computer and DECtape storage. The electron-density profiles show good agreement with results from other eclipses. The partial-reflection programs were changed after the eclipse data collection to improve the operation of the partial-reflection system. These changes were mainly due to expanded computer hardware and have simplified the operations of the system considerably

    Study of basic bio-electrochemistry Sixth monthly progress report, 1-31 Aug. 1963

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    Contribution of hydrogen peroxide to electrode reaction in electrochemical cell by considering effect of catalyst on cell curren

    Cosmological Acceleration Through Transition to Constant Scalar Curvature

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    As shown by Parker and Raval, quantum field theory in curved spacetime gives a possible mechanism for explaining the observed recent acceleration of the universe. This mechanism, which differs in its dynamics from quintessence models, causes the universe to make a transition to an accelerating expansion in which the scalar curvature, R, of spacetime remains constant. This transition occurs despite the fact that we set the renormalized cosmological constant to zero. We show that this model agrees very well with the current observed type-Ia supernova (SNe-Ia) data. There are no free parameters in this fit, as the relevant observables are determined independently by means of the current cosmic microwave background radiation (CMBR) data. We also give the predicted curves for number count tests and for the ratio, w(z), of the dark energy pressure to its density, as well as for dw(z)/dz versus w(z). These curves differ significantly from those obtained from a cosmological constant, and will be tested by planned future observations.Comment: 31 pages, 7 figures; to appear in ApJ. Corrected numerical results; described quantum basis of theory; 18 references added; 2 figures adde

    Comparative Microbial Dynamics in Crassostrea virginica and Crassostrea ariakensis

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    Considerations to introduce the Suminoe or Asian oyster Crassostrea ariakensis along the East Coast have raised many questions regarding ecology, economics, and human health. To date, research has focused primarily on the ecological and socioeconomic implications of this initiative, yet few studies have assessed its potential impact on public health. Our work compares the rates of bioaccumulation, depuration and post harvest decay of indicator organisms (such as E. coli) and Vibrio sp. between Crassostrea virginica and Crassostrea ariakensis in the laboratory. Preliminary results suggest that the rates of bioaccumulation of E. coli in Crassostrea ariakensis were significantly lower than those for Crassostrea virginica, depuration of E. coli was variable between the two species, and Crassostrea ariakensis post harvest decay rates of Vibrio sp. were significantly lower than Crassostrea virginica. This research provides coastal managers with insight into the response of Crassostrea ariakensis to bacteria, an important consideration for determining appropriate management strategies for this species. Further field-based studies will be necessary to elucidate the mechanisms responsible for the differences in rates of bioaccumulation and depuration. (PDF contains 40 pages

    Research program to develop alloys for up to 1200 deg F strain gages

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    Test results on suitability of 15 alloys for use in strain gages at temperatures up to 1200 deg

    The deep-sea fish, Malacosteus

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    Comparing key compositional indicators in Jupiter with those in extra-solar giant planets

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    Spectroscopic transiting observations of the atmospheres of hot Jupiters around other stars, first with Hubble Space Telescope and then Spitzer, opened the door to compositional studies of exoplanets. The James Webb Space Telescope will provide such a profound improvement in signal-to-noise ratio that it will enable detailed analysis of molecular abundances, including but not limited to determining abundances of all the major carbon- and oxygen-bearing species in hot Jupiter atmospheres. This will allow determination of the carbon-to-oxygen ratio, an essential number for planet formation models and a motivating goal of the Juno mission currently around JupiterComment: Submitted to the Astro2020 Decadal Survey as a white paper; thematic areas "Planetary Systems" and "Star and Planet Formation

    Comparing Infrared Dirac-Born-Infeld Brane Inflation to Observations

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    We compare the Infrared Dirac-Born-Infeld (IR DBI) brane inflation model to observations using a Bayesian analysis. The current data cannot distinguish it from the \LambdaCDM model, but is able to give interesting constraints on various microscopic parameters including the mass of the brane moduli potential, the fundamental string scale, the charge or warp factor of throats, and the number of the mobile branes. We quantify some distinctive testable predictions with stringy signatures, such as the large non-Gaussianity, and the large, but regional, running of the spectral index. These results illustrate how we may be able to probe aspects of string theory using cosmological observations.Comment: 54 pages, 13 figures. v2: non-Gaussianity constraint has been applied to the model; parameter constraints have tightened significantly, conclusions unchanged. References added; v3, minor revision, PRD versio

    Occupational Linguistic Niches and the Wage Growth of Latino Immigrants

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    Does the concentration of recent Latino immigrants into occupational linguistic niches--occupations with large numbers of other Spanish speakers—restrict their wage growth? On the one hand, it is possible that Latino immigrants who are concentrated in jobs with large numbers of Spanish speakers may have less onthe- job exposure to English, which may isolate them socially and linguistically and limit their subsequent economic mobility. On the other hand, working in linguistic niches can also be beneficial for upwardly mobile immigrants if it allows them to gain a foothold in the United States while they improve their English skills and develop labor market experience. Using data from the 1996, 2001 and 2004 panels of the Survey of Income and Program Participation (SIPP), we test for the effect of working in occupational linguistic niches on wages and wage growth. The results show that while workers in linguistic niche occupations earn lower wages on average, they do not experience lower rates of wage growth over time. Moreover, we find that about 20 percent of workers who start the 4-year SIPP panel in linguistic niches experience occupational mobility that reduces the percentage of workers speaking Spanish in their occupation by over 10 percent over the course of the study, and these モmoversヤ have higher levels of wage growth than other workers in the sample

    An architecture for IEEE 802.16 MAC scheduler design

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    Copyright © 2007 IEEEThe scheduling algorithm for IEEE 802.16 broadband wireless access system has been left open in the standard. In this paper, we consider three criteria that we have identified as important criteria for an 802.16 scheduler: Service Type differentiation, dynamic sub-frame partition and Subscriber Station differentiation. We investigate the scheduler design from a general perspective, based on these three criteria
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