1,782 research outputs found
Arkansas Corn and Grain Sorghum Performance Tests 2003
Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers
Stellar Population Effects on the Inferred Photon Density at Reionization
The relationship between stellar populations and the ionizing flux with which
they irradiate their surroundings has profound implications for the evolution
of the intergalactic medium. We quantify the ionizing flux arising from
synthetic stellar populations which incorporate the evolution of interacting
binary stars. We determine that these show ionizing flux boosted by 60 per cent
at 0.05 < Z < 0.3 Z_sun and a more modest 10-20 per cent at near-Solar
metallicities relative to star-forming populations in which stars evolve in
isolation. The relation of ionizing flux to observables such as 1500A continuum
and ultraviolet spectral slope is sensitive to attributes of the stellar
population including age, star formation history and initial mass function. For
a galaxy forming 1 M_sun yr^{-1}, observed at > 100 Myr after the onset of star
formation, we predict a production rate of photons capable of ionizing
hydrogen, N_ion = 1.4 x 10^{53} s^{-1} at Z = Z_sun and 3.5 x 10^{53} s^{-1} at
0.1 Z_sun, assuming a Salpeter-like initial mass function. We evaluate the
impact of these issues on the ionization of the intergalactic medium, finding
that the known galaxy populations can maintain the ionization state of the
Universe back to z ~ 9, assuming that their luminosity functions continue to
M_UV = -10, and that constraints on the intergalactic medium at z ~ 2 - 5 can
be satisfied with modest Lyman continuum photon escape fractions of 4 - 24 per
cent depending on assumed metallicity.Comment: 17 pages, accepted by MNRAS. BPASS models can be found at
http://bpass.auckland.ac.nz
Arkansas Soybean Performance Tests 2008
Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producer
Arkansas Soybean Performance Tests 2007
Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producers
Dynamics of a polariton condensate transistor switch
We present a time-resolved study of the logical operation of a polariton
condensate transistor switch. Creating a polariton condensate (source) in a
GaAs ridge-shaped microcavity with a non-resonant pulsed laser beam, the
polariton propagation towards a collector, at the ridge edge, is controlled by
a second weak pulse (gate), located between the source and the collector. The
experimental results are interpreted in the light of simulations based on the
generalized Gross-Pitaevskii equation, including incoherent pumping, decay and
energy relaxation within the condensate.Comment: 4 pages, 2 figure
Operation speed of polariton condensate switches gated by excitons
We present a time-resolved photoluminescence (PL) study in real- and
momentum-space of a polariton condensate switch in a quasi-1D semiconductor
microcavity. The polariton flow across the ridge is gated by excitons inducing
a barrier potential due to repulsive interactions. A study of the device
operation dependence on the power of the pulsed gate beam obtains a
satisfactory compromise for the ON/OFF-signal ratio and -switching time of the
order of 0.3 and ps, respectively. The opposite transition is
governed by the long-lived gate excitons, consequently the OFF/ON-switching
time is ps, limiting the overall operation speed of the device
to GHz. The experimental results are compared to numerical
simulations based on a generalized Gross-Pitaevskii equation, taking into
account incoherent pumping, decay and energy relaxation within the condensate.Comment: 11 pages, 11 figure
Arkansas Corn and Grain Sorghum Performance Tests 2002
Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers. The 2002 corn performance tests contained 59 entries and were conducted at the Northeast Research and Extension Center (NEREC) at Keiser, the Cotton Branch Station (CBS) near Marianna, the Bell Farming Company (BFC) near Des Arc, the Southeast Research and Extension Center - Rohwer Division (SEREC-RD) near Rohwer, and the John Williams Farm (JWF) in Lafayette County. The 2002 grain sorghum performance tests contained 34 entries and were conducted at the NEREC at Keiser, the CBS near Marianna, the Pine Tree Experiment Station (PTS) near Pine Tree, the SEREC-RD near Rohwer, and the Rice Research and Extension Center (RREC) near Stuttgart. Test location maps for grain sorghum and corn can be found inside the back cover
Arkansas Soybean Performance Tests 2002
Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producers. The 2002 soybean cultivar performance tests were conducted at the Northeast Research and Extension Center (NEREC) at Keiser, the Cotton Branch Station (CBS) near Marianna, the Rice Research and Extension Center (RREC) near Stuttgart, the Southeast Research and Extension Center - Rohwer Division (SEREC-RD) near Rohwer, the Burton Brothers Farm (BBF) in LaFayette County, and the Vegetable Substation (VSS) near Kibler. A test location map can be found inside the back cover
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