626 research outputs found
Guía para el uso de dispositivos Android en el llenado de encuestas bajo la plataforma Open Data Kit
Open Data Kit es una caja de herramientas para colección móvil de datos aplicando TIC. Se desarrolló en el departamento de ciencias de la computación e ingeniería de University of Washington. ODK tiene varias ventajas: 1) es de libre uso y acceso; y 2) en la página Web de ODK está toda la información para desarrollar exitosamente una encuesta http://opendatakit.org/. Este manual tiene como fin guiar a los usuarios en el uso de Open Data Kit (ODK) como herramienta para la recolección y procesamiento de los datos de campo para usuarios con un mínimo de conocimiento de computación y de navegación en internet. De esta forma la principal contribución del proyecto sería facilitar a los socios sobre el uso y manejo de estas tecnologías y su adaptación en las diferentes actividades que como ogranización ejecutan
Quintessential inflation from 5D warped product spaces on a dynamical foliation
Assuming the existence of a 5D purely kinetic scalar field on the class of
warped product spaces we investigate the possibility of mimic both an
inflationary and a quintessential scenarios on 4D hypersurfaces, by
implementing a dynamical foliation on the fifth coordinate instead of a
constant one. We obtain that an induced chaotic inflationary scenario with a
geometrically induced scalar potential and an induced quasi-vacuum equation of
state on 4D dynamical hypersurfaces is possible. While on a constant foliation
the universe can be considered as matter dominated today, in a family of 4D
dynamical hypersurfaces the universe can be passing for a period of accelerated
expansion with a deceleration parameter nearly -1. This effect of the dynamical
foliation results negligible at the inflationary epoch allowing for a chaotic
scenario and becomes considerable at the present epoch allowing a
quintessential scenario.Comment: 7 pages, 1 figure Accepted for publication in Modern Physics Letters
Estrategias de marketing empleadas por los graduados de la facultad de odontología, UAM, 1999-2003
Tesis (Cirujano Dentista)--Universidad Americana, Managua, 2008El presente estudio identifica la utilización de Estrategias de Marketing por parte de los odontólogos graduados de la Facultad de Odontología, UAM, en el manejo de sus consultorios. Es un estudio, que provee información para evaluar el conocimiento empresarial de los graduados, como para tener un poco más de conciencia sobre este tema y para conocer el nivel de satisfacción profesional alcanzado por parte de los graduados de la Facultad de Odontología durante el periodo 1999-2003
General Relativity and Weyl Geometry
We show that the general theory of relativity can be formulated in the
language of Weyl geometry. We develop the concept of Weyl frames and point out
that the new mathematical formalism may lead to different pictures of the same
gravitational phenomena. We show that in an arbitrary Weyl frame general
relativity, which takes the form of a scalar-tensor gravitational theory, is
invariant with respect to Weyl tranformations. A kew point in the development
of the formalism is to build an action that is manifestly invariant with
respect to Weyl transformations. When this action is expressed in terms of
Riemannian geometry we find that the theory has some similarities with
Brans-Dicke gravitational theory. In this scenario, the gravitational field is
not described by the metric tensor only, but by a combination of both the
metric and a geometrical scalar field. We illustrate this point by, firstly,
discussing the Newtonian limit in an arbitrary frame, and, secondly, by
examining how distinct geometrical and physical pictures of the same phenomena
may arise in different frames. To give an example, we discuss the gravitational
spectral shift as viewed in a general Weyl frame. We further explore the
analogy of general relativity with scalar-tensor theories and show how a known
Brans-Dicke vacuum solution may appear as a solution of general relativity
theory when reinterpreted in a particular Weyl frame. Finally, we show that the
so-called WIST gravity theories are mathematically equivalent to Brans-Dicke
theory when viewed in a particular frame.Comment: LATEX, 22 page
Scale invariant scalar metric fluctuations during inflation: non-perturbative formalism from a 5D vacuum
We extend to 5D an approach of a 4D non-perturbative formalism to study
scalar metric fluctuations of a 5D Riemann-flat de Sitter background metric. In
contrast with the results obtained in 4D, the spectrum of cosmological scalar
metric fluctuations during inflation can be scale invariant and the background
inflaton field can take sub-Planckian values.Comment: final version to be published in Eur. Phys. J.
Inducing the cosmological constant from five-dimensional Weyl space
We investigate the possibility of inducing the cosmological constant from
extra dimensions by embedding our four-dimensional Riemannian space-time into a
five-dimensional Weyl integrable space. Following approach of the induced
matter theory we show that when we go down from five to four dimensions, the
Weyl field may contribute both to the induced energy-tensor as well as to the
cosmological constant, or more generally, it may generate a time-dependent
cosmological parameter. As an application, we construct a simple cosmological
model which has some interesting properties.Comment: 7 page
Conformally flat spacetimes and Weyl frames
We discuss the concepts of Weyl and Riemann frames in the context of metric
theories of gravity and state the fact that they are completely equivalent as
far as geodesic motion is concerned. We apply this result to conformally flat
spacetimes and show that a new picture arises when a Riemannian spacetime is
taken by means of geometrical gauge transformations into a Minkowskian flat
spacetime. We find out that in the Weyl frame gravity is described by a scalar
field. We give some examples of how conformally flat spacetime configurations
look when viewed from the standpoint of a Weyl frame. We show that in the
non-relativistic and weak field regime the Weyl scalar field may be identified
with the Newtonian gravitational potential. We suggest an equation for the
scalar field by varying the Einstein-Hilbert action restricted to the class of
conformally-flat spacetimes. We revisit Einstein and Fokker's interpretation of
Nordstr\"om scalar gravity theory and draw an analogy between this approach and
the Weyl gauge formalism. We briefly take a look at two-dimensional gravity as
viewed in the Weyl frame and address the question of quantizing a conformally
flat spacetime by going to the Weyl frame.Comment: LATEX - 18 page
Foodways in transition: food plants, diet and local perceptions of change in a Costa Rican Ngäbe community
Background
Indigenous populations are undergoing rapid ethnobiological, nutritional and socioeconomic transitions while being increasingly integrated into modernizing societies. To better understand the dynamics of these transitions, this article aims to characterize the cultural domain of food plants and analyze its relation with current day diets, and the local perceptions of changes given amongst the Ngäbe people of Southern Conte-Burica, Costa Rica, as production of food plants by its residents is hypothesized to be drastically in recession with an decreased local production in the area and new conservation and development paradigms being implemented.
Methods
Extensive freelisting, interviews and workshops were used to collect the data from 72 participants on their knowledge of food plants, their current dietary practices and their perceptions of change in local foodways, while cultural domain analysis, descriptive statistical analyses and development of fundamental explanatory themes were employed to analyze the data.
Results
Results show a food plants domain composed of 140 species, of which 85 % grow in the area, with a medium level of cultural consensus, and some age-based variation. Although many plants still grow in the area, in many key species a decrease on local production–even abandonment–was found, with much reduced cultivation areas. Yet, the domain appears to be largely theoretical, with little evidence of use; and the diet today is predominantly dependent on foods bought from the store (more than 50 % of basic ingredients), many of which were not salient or not even recognized as ‘food plants’ in freelists exercises. While changes in the importance of food plants were largely deemed a result of changes in cultural preferences for store bought processed food stuffs and changing values associated with farming and being food self-sufficient, Ngäbe were also aware of how changing household livelihood activities, and the subsequent loss of knowledge and use of food plants, were in fact being driven by changes in social and political policies, despite increases in forest cover and biodiversity.
Conclusions
Ngäbe foodways are changing in different and somewhat disconnected ways: knowledge of food plants is varied, reflecting most relevant changes in dietary practices such as lower cultivation areas and greater dependence on food from stores by all families. We attribute dietary shifts to socioeconomic and political changes in recent decades, in particular to a reduction of local production of food, new economic structures and agents related to the State and globalization
The tricot citizen science approach applied to on-farm variety evaluation: methodological progress and perspectives
Tricot (triadic comparisons of technologies) is a citizen science approach for testing technology options in their
use environments, which is being applied to on-farm testing of crop varieties. Over the last years, important
progress has been made on the tricot methodology of which an overview is given. Trial dimensions depend on
several factors but tricot implies that plot size is as small as possible to include farmers with small plots (yet
avoiding excessive interplot competition) while many locations are included to ensure representativeness of
trials. Gender and socio-economic work is focused on better household characterization and recruitment
strategies that move beyond sex-aggregation to address aspects of intersectionality. Ethics, privacy and
traditional knowledge aspects will be addressed through expanding digital support in this direction. Genetic gain
estimates need to be addressed by yield measurements, which can be generated by farmers themselves. There
is conceptual clarity about the needs for documentation of trials and publishing data but this aspect requires
further digital development. Much progress has been made on the ClimMob digital platform already, which is
user friendly and supports trials in the main steps and includes open-source data analytics packages. Further
improvements need to be made to ensure better integration with other tools. A next step will be the
development of scaling strategies that involve business development. An important input into these strategies
are economic studies, which are ongoing
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