6,873 research outputs found
Cosmic Microwave Background temperature and polarization anisotropies from the large-N limit of global defects
We determine the full C_l spectra and correlation functions of the
temperature and polarization anisotropies in the CMB, generated by a source
modeled by the large N limit of spontaneously broken global O(N)-theories. We
point out a problem in the standard approach of treating the radiation-matter
transition by interpolating the eigenvectors of the unequal-time correlators of
the source energy-momentum tensor. This affects the CMB predictions from all
type of cosmic defects. We propose a method to overcome this difficulty, and
find that in the large-N global model that we study, differences in the final
CMB power spectra amplitudes reach up to 25%, when compared to implementations
of the eigenvector interpolation technique. We discuss as well how to optimally
search for the contribution in the CMB from active sources such as cosmic
defects, in experiments like Planck, COrE and PRISM.Comment: 16+4 pages, 13 figures (Version 2: minor changes to match published
version in PRD
The local B-polarization of the CMB: a very sensitive probe of cosmic defects
We present a new and especially powerful signature of cosmic strings and
other topological or non-topological defects in the polarization of the cosmic
microwave background (CMB). We show that even if defects contribute 1% or less
in the CMB temperature anisotropy spectrum, their signature in the local
-polarization correlation function at angular scales of tens of arc
minutes is much larger than that due to gravitational waves from inflation,
even if the latter contribute with a ratio as big as to the
temperature anisotropies. We show that when going from non-local to local
-polarization, the ratio of the defect signal-to-noise with respect
to the inflationary value increases by about an order of magnitude. Proposed
B-polarization experiments, with a good sensitivity on arcminute scales, may
either detect a contribution from topological defects produced after inflation
or place stringent limits on them. Even Planck should be able to improve
present constraints on defect models by at least an order of magnitude, to the
level of \ep <10^{-7}. A future full-sky experiment like CMBpol, with
polarization sensitivities of the order of K-arcmin, will be able to
constrain the defect parameter \ep=Gv^2 to a few , depending
on the defect model.Comment: Version Published in Physics Letters
Coupled Negative magnetocapacitance and magnetic susceptibility in a Kagome staircase-like compound Co3V2O8
The dielectric constant of the Kagome staircase-like Co3V2O8 polycrystalline
compound has been measured as function of temperature and magnetic field up to
14T. It is found that the application of an external magnetic field suppresses
the anomaly for the dielectric constant beyond 6.1K. Furthermore, its magnetic
field dependence reveals a negative magnetocapacitance which is proportional to
the magnetic susceptibility, suggesting a common magnetostrictive origin for
the magnetic field dependence of the two quantities. This result is very
different from that obtained from the isostructural compound Ni3V2O8 that
presents a peak in the dielectric constant at the incommensurate magnetic phase
transition coupled to a sign change of the magnetocapacitance
La implementación de normas de seguridad industrial y la prevención de riesgos eléctricos en los laboratorios de la especialidad de electricidad de la Facultad de Tecnología de la UNE
La presente tesis tiene como objetivo principal, el proponer e implementar las normas de seguridad industrial y la prevención de riesgos eléctricos en los laboratorios de la especialidad de electricidad, con la finalidad de implementar, el plan de estudios la asignatura de “seguridad industrial y la prevención de riesgos eléctricos”
La implementación de normas de seguridad industrial y la prevención de riesgos eléctricos en los laboratorios de la especialidad de electricidad de la Facultad de Tecnología de la UNE
La presente tesis tiene como objetivo principal, el proponer e implementar las normas de seguridad industrial y la prevención de riesgos eléctricos en los laboratorios de la especialidad de electricidad, con la finalidad de implementar, el plan de estudios la asignatura de “seguridad industrial y la prevención de riesgos eléctricos”
The Power Spectrum for a Multi-Component Inflaton to Second-Order Corrections in the Slow-Roll Expansion
We derive the power spectrum of the density perturbations
produced during inflation up to second-order corrections in the standard
slow-roll approximation for an inflaton with more than one degree of freedom.
We also present the spectral index up to first-order corrections including
previously missing terms, and the running to leading order.Comment: 11 pages, no figure. KAIST-TH 2002/0
Dielectric catastrophe at the magnetic field induced insulator to metal transition in Pr1-xCaxMnO3 (x=0.30, 0.37) crystals
The dielectric permittivity and resistivity have been measured simultaneously
as a function of magnetic field in Pr1-xCaxMnO3 crystals with different doping.
A huge increase of dielectric permittivity was detected near percolation
threshold. The dielectric and conductive properties are found to be mutually
correlated throughout insulator to metal transition evidencing the dielectric
catastrophe phenomenon. Data are analyzed in a framework of Maxwell-Garnett
theory and the Mott-Hubbard theory attributed to the role of strong Coulomb
interactions.Comment: 5 pages, 5 figure
Inflationary models inducing non-Gaussian metric fluctuations
We construct explicit models of multi-field inflation in which the primordial
metric fluctuations do not necessarily obey Gaussian statistics. These models
are realizations of mechanisms in which non-Gaussianity is first generated by a
light scalar field and then transferred into curvature fluctuations. The
probability distribution functions of the metric perturbation at the end of
inflation are computed. This provides a guideline for designing strategies to
search for non-Gaussian signals in future CMB and large scale structure
surveys.Comment: 4 pages, 7 figure
Baryogenesis by R-parity violating top quark decays and neutron-antineutron oscillations
Generation of the cosmological baryon asymmetry in SUSY based model with
broken R-parity and low scale gravity is considered. The model allows for a
long-life time or even stable proton and observable neutron-antineutron
oscillations.Comment: 26 pages, 2 figures, uses axodraw.sty, added reference
Teaching to Get Nurses an Midwives Empowering Women: Nursing Students’ Perceptions on Professional´s Roles during Perinatal Care
Female empowerment is a key concept in the current healthcare environment, especially in perinatal care. The educational process offered by universities to train future nurses and midwives has a great influence on their professional attitude and performance. To be able to educate in a way that encourages empowerment, it is essential for higher education institutions to know the starting point relating to students’ opinions on the subject. It was conducted a cross-sectional descriptive observational study, at the University of Huelva. It used a self-developed, semi-structured questionnaire, previously validated, to gather quantitative and qualitative data. A total of 117 nursing student were surveyed. Participants consider that general nurses supplement the work of the midwife and acts as a facilitator for the process of women’s empowerment in the perinatal period. They believe that the midwife is the professional figure of reference and the one in which they place greater trust. Improvement proposals for both types of professionals are based on improving training and resources. To encourage the development of the profession and improve the quality of care, it is essential to introduce features related to women’s empowerment in the undergraduate training of future nurses and midwives
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