1,723 research outputs found
Menopausia, el inicio del envejecimiento de las mujeres chilenas. Un estudio cualitativo
Indexación: Scopus.Objective. To develop the meaning of menopause of a group of post-menopausal women and their relationship with aging. Methods. Qualitative descriptive study on 15 Chilean women that completed a taped face-to-face in depth interview that were interpreted according to Krippendorff. Results. A qualitative content analysis revealed the presence of two themes: (a) Cessation of women's reproductive stage and (b) a life transition to aging. Conclusion. Women perceived their menopause as the beginning of aging focusing on the end of fertility and the social connotation that this new role implies. Feeling old 10 years before the customary beginning of old age is an important starting point to be incorporated in women's health education.http://ref.scielo.org/x7bfh
Green's function approach to Chern-Simons extended electrodynamics: an effective theory describing topological insulators
Boundary effects produced by a Chern-Simons (CS) extension to electrodynamics
are analyzed exploiting the Green's function (GF) method. We consider the
electromagnetic field coupled to a -term in a way that has been
proposed to provide the correct low energy effective action for topological
insulators (TI). We take the -term to be piecewise constant in
different regions of space separated by a common interface , to be
called the -boundary. Features arising due to the presence of the
boundary, such as magnetoelectric effects, are already known in CS extended
electrodynamics and solutions for some experimental setups have been found with
specific configuration of sources. In this work we illustrate a method to
construct the GF that allows to solve the CS modified field equations for a
given -boundary with otherwise arbitrary configuration of sources. The
method is illustrated by solving the case of a planar -boundary but can
also be applied for cylindrical and spherical geometries for which the
-boundary can be characterized by a surface where a given coordinate
remains constant. The static fields of a point-like charge interacting with a
planar TI, as described by a planar discontinuity in , are calculated
and successfully compared with previously reported results. We also compute the
force between the charge and the -boundary by two different methods,
using the energy momentum tensor approach and the interaction energy calculated
via the GF. The infinitely straight current-carrying wire is also analyzed
Electro and magneto statics of topological insulators as modeled by planar, spherical and cylindrical boundaries: Green function approach
The Green function (GF) method is used to analyze the boundary effects
produced by a Chern Simons (CS) extension to electrodynamics. We consider the
electromagnetic field coupled to a term that is piecewise constant in
different regions of space, separated by a common interface , the
boundary, model which we will refer to as electrodynamics
( ED). This model provides a correct low energy effective action for
describing topological insulators (TI). In this work we construct the static GF
in ED for different geometrical configurations of the
boundary, namely: planar, spherical and cylindrical interfaces. Also
we adapt the standard Green theorem to include the effects of the
boundary. These are the most important results of our work, since they allow to
obtain the corresponding static electric and magnetic fields for arbitrary
sources and arbitrary boundary conditions in the given geometries. Also, the
method provides a well defined starting point for either analytical or
numerical approximations in the cases where the exact analytical calculations
are not possible. Explicit solutions for simple cases in each of the
aforementioned geometries for boundaries are provided. The adapted
Green theorem is illustrated by studying the problem of a point like electric
charge interacting with a planar TI with prescribed boundary conditions. Our
generalization, when particularized to specific cases, is successfully compared
with previously reported results, most of which have been obtained by using the
methods of images.Comment: 24 pages, 4 figures, accepted for publication in PRD. arXiv admin
note: text overlap with arXiv:1511.0117
Uncertainties in climate change projections and regional downscaling: implications for water resources management
Climate change is expected to have a large impact on water resources worldwide. A major problem in assessing the potential impact of a changing climate on these resources is the difference in spatial scale between available climate change projections and water resources management. Regional climate models (RCMs) are often used for the spatial disaggregation of the outputs of global circulation models. However, RCMs are time-intensive to run and typically only a small number of model runs is available for a certain region of interest. This paper investigates the value of the improved representation of local climate processes by a regional climate model for water resources management in the tropical Andes of Ecuador. This region has a complex hydrology and its water resources are under pressure. Compared to the IPCC AR4 model ensemble, the regional climate model PRECIS does indeed capture local gradients better than global models, but locally the model is prone to large discrepancies between observed and modelled precipitation. It is concluded that a further increase in resolution is necessary to represent local gradients properly. Furthermore, to assess the uncertainty in downscaling, an ensemble of regional climate models should be implemented. Finally, translating the climate variables to streamflow using a hydrological model constitutes a smaller but not negligible source of uncertainty
Real sector of the nonminimally coupled scalar field to self-dual gravity
A scalar field nonminimally coupled to gravity is studied in the canonical
framework, using self-dual variables. The corresponding constraints are first
class and polynomial. To identify the real sector of the theory, reality
conditions are implemented as second class constraints, leading to three real
configurational degrees of freedom per space point. Nevertheless, this
realization makes non-polynomial some of the constraints. The original complex
symplectic structure reduces to the expected real one, by using the appropriate
Dirac brackets. For the sake of preserving the simplicity of the constraints,
an alternative method preventing the use of Dirac brackets, is discussed. It
consists of converting all second class constraints into first class by adding
extra variables. This strategy is implemented for the pure gravity case.Comment: Latex file, 22 pages, no figure
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