5,954 research outputs found
National Scientific Facilities and Their Science Impact on Non-Biomedical Research
H-index, proposed by Hirsch is a good indicator of the impact of a
scientist's research. When evaluating departments, institutions or labs, the
importance of h-index can be further enhanced when properly calibrated for
size. Particularly acute is the issue of federally funded facilities whose
number of actively publishing scientists frequently dwarfs that of academic
departments. Recently Molinari and Molinari developed a methodology that shows
the h-index has a universal growth rate for large numbers of papers, allowing
for meaningful comparisons between institutions.
An additional challenge when comparing large institutions is that fields have
distinct internal cultures, with different typical rates of publication and
citation; biology is more highly cited than physics, which is more highly cited
than engineering. For this reason, this study has focused on the physical
sciences, engineering, and technology, and has excluded bio-medical research.
Comparisons between individual disciplines are reported here to provide
contextual framework. Generally, it was found that the universal growth rate of
Molinari and Molinari holds well across all the categories considered,
testifying to the robustness of both their growth law and our results.
The overall goal here is to set the highest standard of comparison for
federal investment in science; comparisons are made with the nations preeminent
private and public institutions. We find that many among the national
facilities compare favorably in research impact with the nations leading
universities.Comment: 22 pages, 7 figure
The leaking mode problem in atmospheric acoustic-gravity wave propagation
The problem of predicting the transient acoustic pressure pulse at long horizontal distances from large explosions in the atmosphere is examined. Account is taken of poles off the real axis and of branch line integrals in the general integral governing the transient waveform. Perturbation techniques are described for the computation of the imaginary ordinate of the poles and numerical studies are described for a model atmosphere terminated by a halfspace with c = 478 m/sec above 125 km. For frequencies less than 0.0125 rad/sec, the GR sub 1 mode, for example, is found to have a frequency dependent amplitude decay of the order of 0.0001 nepers/km. Examples of numerically synthesized transient waveforms are exhibited with and without the inclusion of leaking modes. The inclusion of leaking modes results in waveforms with a more marked beginning rather than a low frequency oscillating precursor of gradually increasing amplitude. Also, the revised computations indicate that waveforms invariably begin with a pressure rise, a result supported by other theoretical considerations and by experimental data
Low redshift star-forming galaxies: What can they teach us about primeval galaxies?
The analysis of the UV plus optical spectra of three star-forming galaxies, Mrk 496, Mrk 357, TOL1924-416, obtained by matching the size of the optical aperture with that of IUE, has given unexpected results. These can be summarized as follows: (1) the dereddened Ly(alpha)/H(beta) ratios are consistent with the prediction of case B recombination for nebular emission, within the uncertainties; (2) the decrease of the Ly(alpha)/H(beta) ratio with increasing metallicities is not confirmed in our three objects, although the sample is too small to consider this result definitive. The first result is surprising, mainly because at least the two Markarian galaxies have a large enough H1 content to markedly increase the optical depth for the Ly(alpha) photons and to trigger their absorption by dust. This finding can probably be explained as an effect of the inhomogeneous distribution of gas and dust within the galaxies. On the basis of these results, we conclude that the detection of the Ly(alpha) emission line in searching for primeval galaxies (PG's) can be still considered a valid technique
Experimental Research on 4-Duct Tandem VTOL Aircraft Configurations
This paper presents a brief summary of several wind-tunnel investigations conducted at the Langley Research Center of the NASA to study the aerodynamic and stability and control characteristics of several VTOL aircraft configurations powered by four tilting ducted propellers arranged in tandem pairs. Specifically the two rear ducts could be mounted close alongside the upper rear portion of the fuselage with small wing panels attached to the outboard side of the ducts or could be mounted outboard on the tips of a small wing located high on the rear portion of the fuselage. The two front ducts were always mounted close inboard on the forward part of the fuselage and could be mounted either in a high or low position on the fuselage. The results of the investigation indicated that aircraft of this type could have acceptable aerodynamic and static longitudinal and lateral stability and control characteristics in both transition and normal cruise flight except for the possible qualification that the lateral force due to sideslip is abnormally high and might cause the aircraft to be too sensitive to side gusts
Christian Publishing: A Panel Discussion
The 2007 conference of the Association of Christian Librarians convened in Grand Rapids, Michigan, on the campus of Cornerstone University. Conference planners invited representatives of four prominent Christian publishers headquartered there (Baker, Eerdmans, Kregel, and Zondervan) to participate in a panel discussion on June 13. The panelists’ 65-minute exchange is transcribed here in slightly abbreviated form. At the beginning of the discussion, panelists were asked to reflect on general trends in the Christian publishing industry. This led naturally to a lengthy conversation about the publishers’ involvement in the creation and licensing of ebooks and other digital products. Finally, panelists were asked to address the proliferation of English Bible versions aimed at the evangelical community
The Spectral Energy Distribution of Normal, Starburst and Active Galaxies
We present the results of an extensive literature search of multiwavelength
data for a sample of 59 galaxies, consisting of 26 Starbursts, 15 Seyfert 2's,
5 LINER's, 6 normal spirals and 7 normal elliptical galaxies. The data include
soft X-ray fluxes, ultraviolet and optical spectra, near, mid/far infrared
photometry and radio measurements, selected to match as closely as possible the
IUE aperture (10" X 20"). The galaxies are separated into 6 groups with similar
characteristics, namely, Ellipticals, Spirals, LINER's, Seyfert 2's, Starbursts
of Low and High reddening, for which we create average spectral energy
distributions (SED). The individual groups SED's are normalized to the
7000\AA flux and compared, looking for similarities and differences
among them.The bolometric fluxes of different types of galaxies were calculated
integrating their SED's. These values are compared with individual waveband
flux densities, in order to determine the wavebands which contribute most to
the bolometric flux. Linear regressions were performed between the bolometric
and individual band fluxes for each kind of galaxy. These fits can be used in
the calculation of the bolometric flux for other objects of similar activity
type, but with reduced waveband information. We have also collected
multiwavelength data for 4 HII regions, a thermal supernova remnant, and a
non-thermal supernova remnant (SNR), which are compared with the Starburst
SED's.Comment: 29 pages, 13 postscript figures and 10 tables. To appear in The
Astronomical Journa
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