8,468 research outputs found
Asymptotically anomalous black hole configurations in gravitating nonlinear electrodynamics
We analyze the class of non-linear electrodynamics minimally coupled to
gravitation supporting asymptotically flat \textit{non Schwarzschild-like}
elementary solutions. The Lagrangian densities governing the dynamics of these
models in flat space are defined and fully characterized as a subclass of the
set of functions of the two standard field invariants, restricted by
requirements of regularity, parity invariance and positivity of the energy,
which are necessary conditions for the theories to be physically admissible.
Such requirements allow for a complete characterization and classification of
the geometrical structures of the elementary solutions for the corresponding
gravity-coupled models. In particular, an immediate consequence of the
requirement of positivity of the energy is the asymptotic flatness of
gravitating elementary solutions for any admissible model. The present
analysis, together with the (already published) one concerning the full class
of admissible gravitating non-linear electrodynamics supporting asymptotically
flat \textit{Schwarzschild-like} elementary solutions, completes and exhausts
the study of the gravitating point-like charge problem for this kind of models.Comment: 12 pages, 6 figures, revtex4, added extra paragraph in conclusions,
added some references, added other minor changes, to published in Phys.Rev.
Parallel imports, innovations and national welfare: The role of the sizes of the income classes and national markets for health care.
This paper shows that regardless of any intra-country income differences, parallel imports result in a lower level of health-care innovation but, contrary to popular as well as conventional theoretical wisdom, a lower price in the Third World compared to market-based discrimination. Despite such a lower price, however, parallel imports unambiguously make all buyers in the Third World worse off when intra-country income disparity exists. On the other hand, even discarding the MNC's profit, there will be cases in which the richer country prefers price discrimination as well. That is, in those cases, no countries will have any incentive under the welfare criterion to undo price discrimination, contrary to Richardso
Electrostatic spherically symmetric configurations in gravitating nonlinear electrodynamics
We perform a study of the gravitating electrostatic spherically symmetric
(G-ESS) solutions of Einstein field equations minimally coupled to generalized
non-linear abelian gauge models in three space dimensions. These models are
defined by lagrangian densities which are general functions of the gauge field
invariants, restricted by some physical conditions of admissibility. They
include the class of non-linear electrodynamics supporting ESS non-topological
soliton solutions in absence of gravity. We establish that the qualitative
structure of the G-ESS solutions of admissible models is fully characterized by
the asymptotic and central-field behaviours of their ESS solutions in flat
space (or, equivalently, by the behaviour of the lagrangian densities in vacuum
and on the point of the boundary of their domain of definition, where the
second gauge invariant vanishes). The structure of these G-ESS configurations
for admissible models supporting divergent-energy ESS solutions in flat space
is qualitatively the same as in the Reissner-Nordstr\"om case. In contrast, the
G-ESS configurations of the models supporting finite-energy ESS solutions in
flat space exhibit new qualitative features, which are discussed in terms of
the ADM mass, the charge and the soliton energy. Most of the results concerning
well known models, such as the electrodynamics of Maxwell, Born-Infeld and the
Euler-Heisenberg effective lagrangian of QED, minimally coupled to gravitation,
are shown to be corollaries of general statements of this analysis.Comment: 11 pages, revtex4, 4 figures; added references; introduction,
conclusions and several sections extended, 2 additional figures included,
title change
Context-aware mobile app for the multidimensional assessment of the elderly,
Rural areas in Europe are presenting a decreasing population density and an increasing age index. These elders usually present multiple diseases that require complex tools to identify the exact cares that they need. Currently, different frameworks can evaluate their functional status and identify the required cares to maintain their Quality of Life, together with the associated cost to the health system. Nevertheless, these frameworks are usually questionnaires that have to be performed by already overloaded professionals. In this paper, we make use of mobile technologies to build a system capable of monitoring the activities of the elderly and analysing these data to assess their functional status. The experiments carried out show us that it correctly evaluates these patients and reduces the effort required by health professionals
Enriched elderly virtual profiles by means of a multidimensional integrated assessment platform
The pressure over Healthcare systems is increasing in most developed countries. The generalized aging of the population is one of the main causes. This situation is even worse in underdeveloped, sparsely populated regions like Extremadura in Spain or Alentejo in Portugal. The authors propose to use the Situational-Context, a technique to seamlessly adapt Internet of Things systems to the needs and preferences of their users, for virtually modeling the elderly. These models could be used to enhance the elderly experience when using those kind of systems without raising the need for technical skills or the costs of implementing such systems by the regional healthcare systems. In this paper, the integration of a multidimensional integrated assessment platform with such virtual profiles is presented. The assessment platform provides and additional source of information for the virtual profiles that is used to better adapt existing systems to the elders needs
Open cluster candidates in the VVVX area: VVVX CL 076 and CL 077
We are reporting some basic parameters of two newly discovered clusters, VVVX CL 076 and CL 077, recently discovered in the galactic disk area covered by the VISTA Variables in the Via Lactea eXtended (VVVX) ESO Public Survey. The preliminary analysis shows that both clusters are young and relatively close to the Sun.Peer reviewedFinal Published versio
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