1,573 research outputs found
Stability window and mass-radius relation for magnetized strange quark stars
The stability of magnetized strange quark matter (MSQM) is investigated
within the phenomenological MIT bag model, taking into account the variation of
the relevant input parameters, namely, the strange quark mass, baryon density,
magnetic field and bag parameter. We obtain that the energy per baryon
decreases as the magnetic field increases, and its minimum value at vanishing
pressure is lower than the value found for SQM. This implies that MSQM is more
stable than non-magnetized SQM. Furthermore, the stability window of MSQM is
found to be wider than the corresponding one of SQM. The mass-radius relation
for magnetized strange quark stars is also derived in this framework.Comment: 12 pages, 6 figures, 3 table
Effects of Low-Energy Laser Irradiation on Sperm Cells Dynamics of Rabbit (Oryctolagus Cuniculus)
Infertility is a world disease in which a couple is unable to achieve pregnancy. There are numerous parameters to determinate fertility; nevertheless, sperm motility is by consensus one of the most important attributes to evaluate male fertility. Contributions to a better understanding of this crucial parameter are imperative; hence, the aim of this investigation was to assess the effect of low-energy laser irradiation on sperm cell dynamics in thawed samples that were cryopreserved. We used a 405 nm blue laser beam to irradiate spermatic cells from rabbit inside a temperature-controlled dispersion chamber at 37 °C; then, we applied an image recognizing system to calculate individual sperm trajectories and velocities. We found that sperms raise its motility after irradiation suggesting that λ=405 nm is an optimal wavelength for spermatic photo-stimulation
A new spin-anisotropic harmonic honeycomb iridate
The physics of Mott insulators underlies diverse phenomena ranging from high
temperature superconductivity to exotic magnetism. Although both the electron
spin and the structure of the local orbitals play a key role in this physics,
in most systems these are connected only indirectly --- via the Pauli exclusion
principle and the Coulomb interaction. Iridium-based oxides (iridates) open a
further dimension to this problem by introducing strong spin-orbit
interactions, such that the Mott physics has a strong orbital character. In the
layered honeycomb iridates this is thought to generate highly spin-anisotropic
interactions, coupling the spin orientation to a given spatial direction of
exchange and leading to strongly frustrated magnetism. The potential for new
physics emerging from such interactions has driven much scientific excitement,
most recently in the search for a new quantum spin liquid, first discussed by
Kitaev \cite{kitaev_anyons_2006}. Here we report a new iridate structure that
has the same local connectivity as the layered honeycomb, but in a
three-dimensional framework. The temperature dependence of the magnetic
susceptibility exhibits a striking reordering of the magnetic anisotropy,
giving evidence for highly spin-anisotropic exchange interactions. Furthermore,
the basic structural units of this material suggest the possibility of a new
family of structures, the `harmonic honeycomb' iridates. This compound thus
provides a unique and exciting glimpse into the physics of a new class of
strongly spin-orbit coupled Mott insulators.Comment: 12 pages including bibliography, 5 figure
Flavour Issues in Leptogenesis
We study the impact of flavour in thermal leptogenesis, including the quantum
oscillations of the asymmetries in lepton flavour space. In the Boltzmann
equations we find different numerical factors and additional terms which can
affect the results significantly. The upper bound on the CP asymmetry in a
specific flavour is weaker than the bound on the sum. This suggests that --
when flavour dynamics is included -- there is no model-independent limit on the
light neutrino mass scale,and that the lower bound on the reheat temperature is
relaxed by a factor ~ (3 - 10).Comment: 19 pages, corrected equations for flavour oscillation
Induced Parity Breaking Term in Arbitrary Odd Dimensions at Finite Temperature
We calculate the exact parity odd part of the effective action
() for massive Dirac fermions in 2d+1 dimensions at finite
temperature, for a certain class of gauge field configurations. We consider
first Abelian external gauge fields, and then we deal with the case of a
non-Abelian gauge group containing an Abelian U(1) subgroup. For both cases, it
is possible to show that the result depends on topological invariants of the
gauge field configurations, and that the gauge transformation properties of
depend only on those invariants and on the winding number
of the gauge transformation.Comment: 10 pages, revtex, no figure
Effective action for QED in 2+1 dimensions at finite temperature
We calculate the effective action for a constant magnetic field and a
time-dependent time-component of the gauge field in 2+1 dimensions at finite
temperature. We also discuss the behaviour of the charge density and the
fermion condensate as order parameters of symmetry breaking.Comment: Latex, 10 pages, no figure
PadrÔes de controle de crises em pacientes com epilepsia de lobo temporal com ou sem esclerose hipocampal
Objective Patients with mesial temporal lobe epilepsy (MTLE) may present unstable pattern of seizures. We aimed to evaluate the occurrence of relapse-remitting seizures in MTLE with (MTLE-HS) and without (MTLE-NL) hippocampal sclerosis. Method We evaluated 172 patients with MTLE-HS (122) or MTLE-NL (50). Relapse-remitting pattern was defined as periods longer than two years of seizure-freedom intercalated with seizure recurrence. Infrequent seizures was considered as up to three seizures per year and frequent seizures as any period of seizures higher than that. Results Thirty-seven (30%) MTLE-HS and 18 (36%) MTLE-NL patients had relapse-remitting pattern (X2, p = 0.470). This was more common in those with infrequent seizures (X2, p < 0.001). Twelve MTLE-HS and one MTLE-NL patients had prolonged seizure remission between the first and second decade of life (X2, p = 0.06). Conclusion Similar proportion of MTLE-HS or MTLE-NL patients present relapse-remitting seizures and this occurs more often in those with infrequent seizures.Patients with mesial temporal lobe epilepsy (MTLE) may present unstable pattern of seizures. We aimed to evaluate the occurrence of relapse-remitting seizures in MTLE with (MTLE-HS) and without (MTLE-NL) hippocampal sclerosis. Method: We evaluated 172 pat7327982FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO2005/56578-4; 2009/54552-9SEM INFORMAĂĂOPacientes com epilepsia do lobo temporal mesial (ELTM) podem apresentar padrĂŁo instĂĄvel de crises epilĂ©pticas. Nosso objetivo foi avaliar ocorrĂȘncia de crises remitente-recorrentes em ELTM com (ELTM-EH) e sem (ELTM-NL) esclerose hipocampal. MĂ©todo: Ava
Statistics of Q-Oscillators, Quons and Relation to Fractional Satistics
The statistics of -oscillators, quons and to some extent, of anyons are
studied and the basic differences among these objects are pointed out. In
particular, the statistical distributions for different bosonic and fermionic
-oscillators are found for their corresponding Fock space representations in
the case when the hamiltonian is identified with the number operator. In this
case and for nonrelativistic particles, the single-particle temperature Green
function is defined with -deformed periodicity conditions. The equations of
state for nonrelativistic and ultrarelativistic bosonic -gases in an
arbitrary space dimension are found near Bose statistics, as well as the one
for an anyonic gas near Bose and Fermi statistics. The first corrections to the
second virial coefficients are also evaluated. The phenomenon of Bose-Einstein
condensation in the -deformed gases is also discussed.Comment: 21 pages, Latex, HU-TFT-93-2
Non-static Dimensional Reduction of QED_3 at Finite Temperature
We study an extreme non-static limit of 2+1-dimensional QED obtained by
making a dimensional reduction so that all fields are spatially uniform but
time dependent. This dimensional reduction leads to a 0+1-dimensional field
theory that inherits many of the features of the 2+1-dimensional model, such as
Chern-Simons terms, time-reversal violation, an analogue of parity violation,
and global U(2) flavor symmetry. At one-loop level, interactions induce a
Chern-Simons term at finite T with coefficient tanh(beta m_F/2), where m_F is
the fermion mass. The finite temperature two loop self-energies are also
computed, and are non-zero for all temperatures.Comment: 28 pp, 11 figures, uses axodraw.st
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