10,658 research outputs found
Tidal stirring and the distribution of phytoplankton in Long Island and Block Island Sounds
Phytoplankton distributions in Long Island and Block Island Sounds measured during a 1978 fall equinox cruise are interpreted in terms of tidal mixing variations and water column stratification. A stratification depth-scaled-by-light diagram is used to quantify the preferred physical environments of the two major morphological groups (diatoms and microflagellates). The success of the method in clearly distinguishing these physical regimes suggests its value as a useful biological growth index in estuarine systems
Integration of Cool- and Warm-Season Grass Pasturing Systems into Cattle Finishing Programs
Previously we reported on a study that demonstrated that fall-born steer calves pastured on bromegrass for either portions of or all of the grazing season and then finished in drylot, significantly outperformed calves placed directly into the feedlot in terms of profit/head at harvest time. Areas consisting of highly productive soils, interdispersed with highly erodable land, are well suited for this kind of production practice and in turn production systems of this nature are quite consistent with the concepts of sustainable agriculture. In an effort to capture more grazing potential, it was decided to incorporate warm-season grasses into the pasture program so that forage production would be enhanced during the hot summer months of July and August when cool-season grasses normally become nearly dormant. Therefore, the objective of this multi-year study is to compare steer calves provided a combination of cool- and warm-season grass pastures with calves provided cool-season grass pastures only and followed by all calves being finished in drylot
Space Station Freedom automation and robotics: An assessment of the potential for increased productivity
This report presents the results of a study performed in support of the Space Station Freedom Advanced Development Program, under the sponsorship of the Space Station Engineering (Code MT), Office of Space Flight. The study consisted of the collection, compilation, and analysis of lessons learned, crew time requirements, and other factors influencing the application of advanced automation and robotics, with emphasis on potential improvements in productivity. The lessons learned data collected were based primarily on Skylab, Spacelab, and other Space Shuttle experiences, consisting principally of interviews with current and former crew members and other NASA personnel with relevant experience. The objectives of this report are to present a summary of this data and its analysis, and to present conclusions regarding promising areas for the application of advanced automation and robotics technology to the Space Station Freedom and the potential benefits in terms of increased productivity. In this study, primary emphasis was placed on advanced automation technology because of its fairly extensive utilization within private industry including the aerospace sector. In contrast, other than the Remote Manipulator System (RMS), there has been relatively limited experience with advanced robotics technology applicable to the Space Station. This report should be used as a guide and is not intended to be used as a substitute for official Astronaut Office crew positions on specific issues
Production of neutral scalar Higgs bosons at colliders
We study the production of neutral scalar (CP even) Higgs bosons in the
process by including supersymmetric corrections to the
dominant -channel photon exchange amplitude. In addition to the standard
model and fermion loops, there are substantial contributions from
chargino loops. For some cases, these contributions can exceed those of the
's and ordinary fermions. The cross sections in this channel are generally
one or two orders of magnitude larger than those in the related channel
.Comment: 12 pages RevTeX, 5 postscript figures included, uses epsf.st
Progress Report: Effects of Condensed Corn Distillers Solubles on Steer Performance and Carcass Composition
This study looked at the use of condensed corn distillers solubles (CCDS) as a feed source for steers backgrounded on pasture as well as steers being fed in the feedlot. In addition, a treatment group was finished on pasture with CCDS as a part of their ration. The two feedlot rations were isocaloric and isonitrogenous. The pasture finishing steers were fed a ration based on the feedlot ration containing CCDS but were not fed any hay. The goal of this study was to establish the benefits, as well as the limitations, of feeding CCDS to feedlot and backgrounded steers
Effects of Condensed Corn Distillers Solubles on Steer Performance and Carcass Composition
Condensed corn distillers solubles (CCDS) have become a prevalent feed source in Iowa. In this study, we looked at the impact of CCDS in finishing steer rations and the influence CCDS had on steer performance as well as carcass composition. In the first year of the study, 112 steers were randomly sorted into four equal groups where each group contained four pens and 7 steers per pen. The second year of the study was a repeat of the first year however a fifth treatment was added in which 28 steers were placed on pasture and provided a finishing grain diet. The first of the four treatments consisted of the feedlot group (F), which was placed directly in to the feedlot and fed shelled corn, alfalfa hay, a protein, vitamin, and mineral supplement, and molasses. The second treatment was feedlot + CCDS (F+CCDS). This treatment group was placed directly into the feedlot and received shelled corn, alfalfa hay, a protein, vitamin and mineral supplement, and CCDS. The third treatment group was backgrounded on pasture for the duration of the summer (P), and then put into the feedlot where they received the same ration as the F group. The fourth treatment group was backgrounded on pasture for the duration of the summer, and while on pasture had access to free choice CCDS via a lick tank (P+CCDS). In the fall this group was placed into the feedlot and received the same ration as the F+CCDS group. In the second year, a fifth treatment was added, called the pasture finishing group (PF). The steers in this treatment received the same shelled corn, and protein, vitamin and mineral supplement, and CCDS as the cattle in the F+CCDS treatment, minus the alfalfa hay. Grass consumption for the PF cattle was estimated using the 2007 BRANDS program. Although the study is not yet completed, it appears as though CCDS can be implemented in feedlot rations successfully. The existing trends of the study would indicate that a feedlot ration containing CCDS will slightly increase steer ADG and improve F:G, without effecting QG
KIC 4768731: a bright long-period roAp star in theKeplerfield
We report the identification of 61.45 d−1 (711.2 μHz) oscillations, with amplitudes of 62.6 μmag, in KIC 4768731 (HD 225914) using Kepler photometry. This relatively bright (V = 9.17) chemically peculiar star with spectral type A5 Vp SrCr(Eu) has previously been found to exhibit rotational modulation with a period of 5.21 d. Fourier analysis reveals a simple dipole pulsator with an amplitude that has remained stable over a 4-yr time span, but with a frequency that is variable. Analysis of high-resolution spectra yields stellar parameters of Teff = 8100 ± 200 K, log g = 4.0 ± 0.2, [Fe/H] = +0.31 ± 0.24 and v sin i = 14.8 ± 1.6 km s−1.
Line profile variations caused by rotation are also evident. Lines of Sr, Cr, Eu, Mg and Si are strongest when the star is brightest, while Y and Ba vary in antiphase with the other elements. The abundances of rare earth elements are only modestly enhanced compared to other roAp stars of similar Teff and log g. Radial velocities in the literature suggest a significant change over the past 30 yr, but the radial velocities presented here show no significant change over a period of 4 yr
Phase Slips and the Eckhaus Instability
We consider the Ginzburg-Landau equation, , with complex amplitude . We first analyze the phenomenon of
phase slips as a consequence of the {\it local} shape of . We next prove a
{\it global} theorem about evolution from an Eckhaus unstable state, all the
way to the limiting stable finite state, for periodic perturbations of Eckhaus
unstable periodic initial data. Equipped with these results, we proceed to
prove the corresponding phenomena for the fourth order Swift-Hohenberg
equation, of which the Ginzburg-Landau equation is the amplitude approximation.
This sheds light on how one should deal with local and global aspects of phase
slips for this and many other similar systems.Comment: 22 pages, Postscript, A
Search for microwave emission from ultrahigh energy cosmic rays
We present a search for microwave emission from air showers induced by
ultrahigh energy cosmic rays with the microwave detection of air showers
experiment. No events were found, ruling out a wide range of power flux and
coherence of the putative emission, including those suggested by recent
laboratory measurements.Comment: 5 pages, 3 figure
Cosmological Imprint of an Energy Component with General Equation of State
We examine the possibility that a significant component of the energy density
of the universe has an equation-of-state different from that of matter,
radiation or cosmological constant (). An example is a cosmic scalar
field evolving in a potential, but our treatment is more general. Including
this component alters cosmic evolution in a way that fits current observations
well. Unlike , it evolves dynamically and develops fluctuations,
leaving a distinctive imprint on the microwave background anisotropy and mass
power spectrum.Comment: revised version, with added references, to appear in Phys. Rev. Lett.
(4 pages Latex, 2 postscript figures
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