4,017 research outputs found
Alfalfa Production and Trends in Kentucky
Alfalfa is often referred to as the Queen of U.S. Forage Production . Looking at all hay production alfalfa should be called The King . In 1991, 83.8 million tons were harvested in the United States -- 55 percent of all the hay harvested in the United States. This total does not include the many tons harvested as green chop, which is an especially common practice among dairy farmers. But, why shouldn\u27t alfalfa be popular? This deep rooted leguminous plant is generally the forage leader in yield, protein, and TDN
A new genus and species of tyrannosauroid from the Late Cretaceous (Middle Campanian) Demopolis Formation of Alabama
Geology and Stratigraphy of the Western Kentucky Coal Field
The Pennsylvanian rocks of the Western Kentucky Coal Field produce between 40 and 55 million tons of coal a year from as many as 45 coal seams; however, three seams produce more than 75 percent of the total. In addition, Pennsylvanian strata contain numerous oil and natural gas reservoirs, tar-sand reservoirs, and industrial minerals. Pennsylvanian sandstones are also some of the most important bedrock aquifers in the coal field. Because of the economic importance of the Pennsylvanian strata to the region and the Commonwealth as a whole, a better understanding of these rocks is needed. This description of the nomenclature of Pennsylvanian strata in the Western Kentucky Coal Field also provides information on their mineral resources and geology. New stratigraphic names, based on regional agreements among the state geological surveys of Kentucky, Illinois, and Indiana, are also presented
Optimization of inhomogeneous electron correlation factors in periodic solids
A method is presented for the optimization of one-body and inhomogeneous
two-body terms in correlated electronic wave functions of Jastrow-Slater type.
The most general form of inhomogeneous correlation term which is compatible
with crystal symmetry is used and the energy is minimized with respect to all
parameters using a rapidly convergent iterative approach, based on Monte Carlo
sampling of the energy and fitting energy fluctuations. The energy minimization
is performed exactly within statistical sampling error for the energy
derivatives and the resulting one- and two-body terms of the wave function are
found to be well-determined. The largest calculations performed require the
optimization of over 3000 parameters. The inhomogeneous two-electron
correlation terms are calculated for diamond and rhombohedral graphite. The
optimal terms in diamond are found to be approximately homogeneous and
isotropic over all ranges of electron separation, but exhibit some
inhomogeneity at short- and intermediate-range, whereas those in graphite are
found to be homogeneous at short-range, but inhomogeneous and anisotropic at
intermediate- and long-range electron separation.Comment: 23 pages, 15 figures, 1 table, REVTeX4, submitted to PR
N-Doped Fe@CNT for Combined RWGS/FT CO <sub>2</sub> Hydrogenation
The conversion of CO<sub>2</sub> into
chemical fuels represents
an attractive route for greenhouse gas emission reductions and renewable
energy storage. Iron nanoparticles supported on graphitic carbon materials
(e.g., carbon nanotubes (CNTs)) have proven themselves to be effective
catalysts for this process. This is due to their stability and ability
to support simultaneous reverse water-gas shift (RWGS) and Fischer–Tropsch
(FT) catalysis. Typically, these catalytic iron particles are postdoped
onto an existing carbon support via wet impregnation. Nitrogen doping
of the catalyst support enhances particle–support interactions
by providing electron-rich anchoring sites for nanoparticles during
wet impregnation. This is typically credited for improving CO<sub>2</sub> conversion and product selectivity in subsequent catalysis.
However, the mechanism for RWGS/FT catalysis remains underexplored.
Current research places significant emphasis on the importance of
enhanced particle–support interactions due to N doping, which
may mask further mechanistic effects arising from the presence or
absence of nitrogen during CO<sub>2</sub> hydrogenation. Here we report
a clear relationship between the presence of nitrogen in the CNT support
of an RWGS/FT iron catalyst and significant shifts in the activity
and product distribution of the reaction. Particle–support
interactions are maximized (and discrepancies between N-doped and
pristine support materials are minimized) by incorporating iron and
nitrogen directly into the support during synthesis. Reactivity is
thus rationalized in terms of the influence of C–N dipoles
in the support upon the adsorption properties of CO<sub>2</sub> and
CO on the surface rather than improved particle–support interactions.
These results show that the direct hydrogenation of CO<sub>2</sub> to hydrocarbons is a potentially viable route to reduce carbon emissions
from human activities
Multifrequency Observations of Radio Pulse Broadening and Constraints on Interstellar Electron Density Microstructure
We have made observations of 98 low-Galactic-latitude pulsars to measure
pulse broadening caused by multipath propagation through the interstellar
medium. Data were collected with the 305-m Arecibo telescope at four radio
frequencies between 430 and 2380 MHz. We used a CLEAN-based algorithm to
deconvolve interstellar pulse broadening from the measured pulse shapes. We
employed two distinct pulse broadening functions (PBFs): PBF is appropriate
for a thin screen of scattering material between the Earth and a pulsar, while
PBF is appropriate for scattering material uniformly distributed along the
line of sight from the Earth to a pulsar. We found that some observations were
better fit by PBF and some by PBF. Pulse broadening times ()
are derived from fits of PBFs to the data, and are compared with the
predictions of a smoothed model of the Galactic electron distribution. Several
lines of sight show excess broadening, which we model as clumps of high density
scattering material. A global analysis of all available data finds that the
pulse broadening scales with frequency, , as \taud \propto\nu^{-\alpha}
where . This is somewhat shallower than the value
expected from a Kolmogorov medium, but could arise if the spectrum
of turbulence has an inner cutoff at 300--800 km. A few objects follow
particularly shallow scaling laws (the mean scaling index \meanalpha \sim 3.1
\pm 0.1 and respectively for the case of PBF and
PBF), which may arise from large scale refraction or from the truncation of
scattering screens transverse to the Earth--pulsar line of sight.Comment: Accepted for publication in the Astrophysical Journal; 32 pages, 11
figure
Non-Newtonian effects in the peristaltic flow of a Maxwell fluid
We analyzed the effect of viscoelasticity on the dynamics of fluids in porous
media by studying the flow of a Maxwell fluid in a circular tube, in which the
flow is induced by a wave traveling on the tube wall. The present study
investigates novelties brought about into the classic peristaltic mechanism by
inclusion of non-Newtonian effects that are important, for example, for
hydrocarbons. This problem has numerous applications in various branches of
science, including stimulation of fluid flow in porous media under the effect
of elastic waves. We have found that in the extreme non-Newtonian regime there
is a possibility of a fluid flow in the direction {\it opposite} to the
propagation of the wave traveling on the tube wall.Comment: to Appear in Phys. Rev. E., 01 September 2001 issu
The effect of sex and laterality on the phenotype of primary rhegmatogenous retinal detachment
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