600 research outputs found
Ensileability of alfalfa: cutting, maturity and treatment effects
Analysis of ensiling characteristics from late-bud, 10% bloom, and 50% bloom alfalfa, taken within each of four cuttings identified higher pre-ensiled dry matter (DM) content during the first two cuttings, whereas crop buffer capacity was weakest during the third cutting and subsequently strongest throughout the fourth cutting. Initial pH was lowest at the first cutting and increased with each cutting thereafter. Dry matter increased linearly within maturity, whereas late-bud maturity had the highest buffer capacity and initial pH. From hr 24 until d 90, the pH values were consistently highest for late-bud and lowest for 50% bloom silage. 1featments receiving 2% dextrose showed a slightly higher DM. At each of seven laboratory silo opening times, a combination of added dextrose and a lactic acid bacteria inoculant yielded the lowest pH; inoculant alone gave the next lowest pH values through hr 48. From d 3 to 90, pH\u27s were consistently highest for control silages, followed by inoculant. dextrose, and dextrose + inoculant combined
The effects of central cholecystokinin receptor blockade on hypothalamic-pituitary-adrenal and symptomatic responses to overnight withdrawal from alprazolam
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142739/1/Abelson-Nesse-alprazolam-BioPsych-1995.pd
Heavy Metal, Organochlorine Pesticide and Polychlorinated Biphenyl Contamination in Arctic Ground Squirrels (Spermophilus Parryi) in Northern Alaska
Heavy metal and organochlorine (OC) concentrations including organochlorine pesticides and polychlorinated biphenyl congeners (PCBs), were determined in arctic ground squirrels (Spermophilus parryi) from three sites in the Brooks Range of northern Alaska in 1991-93. Heavy metals were present in most squirrel livers collected, with concentrations of trace elements (As, Cd, Hg, Ni, and Pb) averaging below 1 micro g/g wet weight. Hexachlorobenzene (HCB), p,p'-DDE, gamma hexachlorocyclohexane (gamma-HCH), trans-nonachlor, and PCBs 138, 153, and 170 were the most frequently detected OCs in fat and liver. Average concentrations of individual OC analytes were below 20 ng/g wet weight in liver and below 15 ng/g wet weight in fat. Rank correlations indicate that concentrations of heavy metals and of OCs accumulate in concert with one another (As, Cd, Cu, and Zn; PCBs 138, 170, and 180). Although heavy metal and OC concentrations are low relative to other areas and other arctic species, the occurrence of these compounds illustrates the global pervasiveness of persistent organic compounds and the potential for bioaccumulation in the terrestrial arctic food web.De 1991 à 1993, on a mesuré les concentrations en métaux lourds et en organochlorés, y compris des pesticides organochlorés et des congénÚres du diphényle polychloré (PCB), chez le spermophile arctique (Spermophilus parryi) à trois endroits situés dans la chaßne de Brooks de l'Alaska septentrional. On a trouvé des métaux lourds dans la plupart des foies de spermophiles prélevés, avec des concentrations en éléments traces (As, Cd, Hg, Ni et Pb) inférieures en moyenne à 1 ”g/g de poids frais. L'hexachlorobenzÚne (HCB), le p,p'-DDE, l'hexachlorocyclohexane gamma (HCH-gamma), le trans-nonachlore et les PCB 138, 153 et 170 étaient les organochlorés les plus fréquemment détectés dans le tissu adipeux et le foie. Les concentrations moyennes des organochlorés analysés individuellement étaient inférieures à 20 ng/g de poids frais pour le foie et à 15 ng/g de poids frais pour le tissu adipeux. Les corrélations de rang révÚlent que les concentrations en métaux lourds augmentent de concert avec celles en organochlorés (As, Cd, Cu et Zn; PCB 138, 170 et 180). Bien que les concentrations en métaux lourds et en organochlorés soient faibles par rapport à celles d'autres régions et à celles d'autres espÚces arctiques, la présence de ces composés illustre l'omniprésence planétaire de composés organiques persistants et le potentiel pour une accumulation biologique dans le réseau trophique terrestre de l'Arctique
Baryon Binding Energy in Sakai-Sugimoto Model
The binding energy of baryon has been studied in the dual
string theory with a black hole interior. In this picture baryon is constructed
of a brane vertex wrapping on and fundamental strings
connected to it. Here, we calculate the baryon binding energy in Sakai-Sugimoto
model with a in which the supersymmetry is completely
broken. Also we check the dependence of the baryon binding energy. We
believe that this model represents an accurate description of baryons due to
the existence of Chern-Simones coupling with the gauge field on the brane. We
obtain an analytical expression for the baryon binding energy . In that case we
plot the baryon binding energy in terms of radial coordinate. Then by using the
binding energy diagram, we determine the stability range for baryon
configuration. And also the position and energy of the stable equilibrium point
is obtained by the corresponding diagram. Also we plot the baryon binding
energy in terms of temperature and estimate a critical temperature in which the
baryon would be dissociated.Comment: 14 pages, 1 fi
The Metallicity Distribution and Hot Jupiter Rate of the Kepler Field: Hectochelle High-resolution Spectroscopy for 776 Kepler Target Stars
The occurrence rate of hot Jupiters from the Kepler transit survey is roughly half that of radial velocity surveys targeting solar neighborhood stars. One hypothesis to explain this difference is that the two surveys target stars with different stellar metallicity distributions. To test this hypothesis, we measure the metallicity distribution of the Kepler targets using the Hectochelle multi-fiber, high-resolution spectrograph. Limiting our spectroscopic analysis to 610 dwarf stars in our sample with > 3.5, we measure a metallicity distribution characterized by a mean of [M H]mean = -0.045 ± 0.009, in agreement with previous studies of the Kepler field target stars. In comparison, the metallicity distribution of the California Planet Search radial velocity sample has a mean of [M H]CPS,mean = -0.005 ± 0.006, and the samples come from different parent populations according to a Kolmogorov-Smirnov test. We refit the exponential relation between the fraction of stars hosting a close-in giant planet and the host star metallicity using a sample of dwarf stars from the California Planet Search with updated metallicities. The best-fit relation tells us that the difference in metallicity between the two samples is insufficient to explain the discrepant hot Jupiter occurrence rates; the metallicity difference would need to be â0.2-0.3 dex for perfect agreement. We also show that (sub)giant contamination in the Kepler sample cannot reconcile the two occurrence calculations. We conclude that other factors, such as binary contamination and imperfect stellar properties, must also be at play
B(E1) Strengths from Coulomb Excitation of 11Be
The (E1;) strength for Be has been extracted from
intermediate energy Coulomb excitation measurements, over a range of beam
energies using a new reaction model, the extended continuum discretized coupled
channels (XCDCC) method. In addition, a measurement of the excitation cross
section for Be+Pb at 38.6 MeV/nucleon is reported. The (E1)
strength of 0.105(12) efm derived from this measurement is consistent
with those made previously at 60 and 64 MeV/nucleon, i n contrast to an
anomalously low result obtained at 43 MeV/nucleon. By coupling a
multi-configuration description of the projectile structure with realistic
reaction theory, the XCDCC model provides for the first time a fully quantum
mechanical description of Coulomb excitation. The XCDCC calculations reveal
that the excitation process involves significant contributions from nuclear,
continuum, and higher-order effects. An analysis of the present and two earlier
intermediate energy measurements yields a combined B(E1) strength of 0.105(7)
efm. This value is in good agreement with the value deduced
independently from the lifetime of the state in Be, and has a
comparable p recision.Comment: 5 pages, 2 figures, accepted for publication in Phys. Lett.
Fermions on an Interval: Quark and Lepton Masses without a Higgs
We consider fermions on an extra dimensional interval. We find the boundary
conditions at the ends of the interval that are consistent with the variational
principle, and explain which ones arise in various physical circumstances. We
apply these results to higgsless models of electroweak symmetry breaking, where
electroweak symmetry is not broken by a scalar vacuum expectation value, but
rather by the boundary conditions of the gauge fields. We show that it is
possible to find a set of boundary conditions for bulk fermions that would give
a realistic fermion mass spectrum without the presence of a Higgs scalar, and
present some sample fermion mass spectra for the standard model quarks and
leptons as well as their resonances.Comment: LaTeX, 36 pages, 5 figure
Helium Clustering in Neutron-Rich Be Isotopes
Measurements of the helium-cluster breakup and neutron removal cross sections
for neutron-rich Be isotopes A=10-12,14 are presented. These have been studied
in the 30 to 42 MeV/u energy range where reaction measurements are proposed to
be sensitive to the cluster content of the ground-state wave-function. These
measurements provide a comprehensive survey of the decay processes of the Be
isotopes by which the valence neutrons are removed revealing the underlying
alpha-alpha core-cluster structure. The measurements indicate that clustering
in the Be isotopes remains important up to the drip-line nucleus 14^Be and that
the dominant helium-cluster structure in the neutron-rich Be isotopes
corresponds to alpha-Xn-alpha.Comment: 5 pages, 2 tables and 3 figure
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