9,561 research outputs found
Three-dimensional Dirac oscillator in a thermal bath
The thermal properties of the three-dimensional Dirac oscillator are
considered. The canonical partition function is determined, and the
high-temperature limit is assessed. The degeneracy of energy levels and their
physical implications on the main thermodynamic functions are analyzed,
revealing that these functions assume values greater than the one-dimensional
case. So that at high temperatures, the limit value of the specific heat is
three times bigger.Comment: 9 pages, 4 figures. Text improved, references added. Revised to match
accepted version in Europhysics Letters
Treating some solid state problems with the Dirac equation
The ambiguity involved in the definition of effective-mass Hamiltonians for
nonrelativistic models is resolved using the Dirac equation. The multistep
approximation is extended for relativistic cases allowing the treatment of
arbitrary potential and effective-mass profiles without ordering problems. On
the other hand, if the Schrodinger equation is supposed to be used, our
relativistic approach demonstrate that both results are coincidents if the
BenDaniel and Duke prescription for the kinetic-energy operator is implemented.
Applications for semiconductor heterostructures are discussed.Comment: 06 pages, 5 figure
Calf health and performance during receiving is not changed by fence-line preconditioning on flint hills range vs. drylot preconditioning
Ranch-of-origin preconditioning can improve the welfare and performance of beef
calves by decreasing the stress associated with weaning, transport, diet change, and
commingling with other calves. Preconditioning methods that involve pasture weaning
coupled with maternal contact (i.e., fence-line weaning) have been promoted as possible
best management practices for minimizing stress. Prior studies focused on performance
and behavior during preconditioning on the ranch of origin. Little information has
been published relating to carryover effects of fence-line preconditioning compared
with conventional drylot preconditioning on performance and behavior during feedlot
receiving.
Our objectives were to measure growth and health during a 28-day ranch-of-origin
preconditioning phase and during a 60-day feedlot receiving phase among beef calves
subjected to 1 of 3 ranch-of-origin preconditioning programs: (1) drylot preconditioning
+ dam separation, (2) pasture preconditioning + fence-line contact with dams, and
(3) pasture preconditioning + fence-line contact with dams + supplemental feed delivered
in a bunk. In addition, we recorded incidences of behavioral distress among these
treatments during first 7 days of feedlot receiving
Kinetic energy of protons in ice Ih and water: a path integral study
The kinetic energy of H and O nuclei has been studied by path integral
molecular dynamics simulations of ice Ih and water at ambient pressure. The
simulations were performed by using the q-TIP4P/F model, a point charge
empirical potential that includes molecular flexibility and anharmonicity in
the OH stretch of the water molecule. Ice Ih was studied in a temperature range
between 210-290 K, and water between 230-320 K. Simulations of an isolated
water molecule were performed in the range 210-320 K to estimate the
contribution of the intramolecular vibrational modes to the kinetic energy. Our
results for the proton kinetic energy, K_H, in water and ice Ih show both
agreement and discrepancies with different published data based on deep
inelastic neutron scattering experiments. Agreement is found for water at the
experimental melting point and in the range 290-300 K. Discrepancies arise
because data derived from the scattering experiments predict in water two
maxima of K_H around 270 K and 277 K, and that K_H is lower in ice than in
water at 269 K. As a check of the validity of the employed water potential, we
show that our simulations are consistent with other experimental thermodynamic
properties related to K_H, as the temperature dependence of the liquid density,
the heat capacity of water and ice at constant pressure, and the isotopic shift
in the melting temperature of ice upon isotopic substitution of either H or O
atoms. Moreover, the temperature dependence of K_H predicted by the q-TIP4P/F
model for ice Ih is found to be in good agreement to results of path integral
simulations using ab initio density functional theory.Comment: 11 pages, 6 figures, 2 table
Evaluation of the geotechnical behaviour of a volcanic soil wall with additions of lime and cement against landslides
The construction of earth walls can be a significant response to prevent the next landslides from reaching the road and avoid accidents. Therefore, a material of the same slope was used and reinforced with mixtures of lime and cement, with this same reinforced material a mechanically stabilized hypothetical earth wall (MSE) was developed. An analysis of the original slope was developed to check if there was a possible failure through its safety factor. Then, a hypothetical wall was developed with a floor reinforced with mixtures, in order to assess its overall safety factor and its maximum landslides. According to the results, in principle it was determined that the dosage M-3 / C-4-4 improves in a range of 30% to 37% the friction angle. In addition, it was found that a reinforced wall, that is to say with Lime and cement additions, presents a better behaviour. In its effect, its displacements are about 8 mm and have a global factor of 1.23
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