1,110 research outputs found
Geophysical constraint on a relic background of the dilatons
According to a scenario in string cosmology, a relic background of light
dilatons can be a significant component of the dark matter in the Universe. A
new approach of searching for such a dilatonic background by observing Earth's
surface gravity was proposed in my previous work. In this paper, the concept of
the geophysical search is briefly reviewed, and the geophysical constraint on
the dilaton background is presented as a function of the strength of the
dilaton coupling, . For simplicity, I focus on massless dilatons and
assume a simple Earth model. With the current upper limit on , we obtain
the upper limit on the dimensionless energy density of the massless background,
, which is about one-order of
magnitude more stringent than the one from astrophysical observations, at the
frequency of 7 10 Hz. If the magnitude of is
experimentally found to be smaller than the current upper limit by one order of
magnitude, the geophysical upper limit on becomes less
stringent and comparable to the one obtained from the astrophysical
observations.Comment: 6 pages, Proceedings for the 8th Edoardo Amaldi Conference on
Gravitational Waves, 21-26 June, 2009, Columbia University, New York, US
On Mechanics and Thermodynamics of a stellar galaxy in a two-component virial system and the Fundamental Plane
The paper confirms the existence of a special configuration (among the
infinite number of virial states) which a B stellar(Baryonic) component may
assume inside a given D dark halo potential well.This satisfies the d'Alembert
Principle of virtual works and its typical dimension works as a scale length
(tidal radius)induced on the gravitational field of the bright component by the
dark one.Its dynamic and thermodynamic properties are here analyzed in
connection with the physical reason for the existence of the Fundamental Plane
(FP) for ellipticals.The analysis is performed by using 2-component models with
two power-law density profiles and two homogeneous cores and compared with some
observable scaling relations for pressure supported ellipticals.The virial
equilibrium stages of the 2-component system have to occur after a previous
violent relaxation phase. If the stellar B component is allowed to cool slowly
its virial evolution consists of a sequence of contractions with enough time to
rearrange the virial equilibrium after any step. The thermodynamic process
during the dynamical evolution is so divided into a sequence of transformations
which are irreversible but occur between two quasi-equilibrium stages.The
analysis allows the conclusion that the induced scale length is a real
confinement for the stellar system. The presence of this specific border on the
space of the baryonic luminous component has to be regarded as the physical
reason why a stellar galaxy belongs to the FP and why astrophysical objects,
with a completely different history and formation, but characterized by a tidal
radius (as the globular clusters are) lie on the same FP. An other problem
addressed is how this special configuration may be reached and why an
elliptical is not completely relaxed in respect to its dark halo.Comment: 42 pages, 7 figures, in press in New Astronomy 200
Orchestrating Forest Policy in Italy: Mission Impossible?
In the Italian political and economic agenda the forest sector occupies a marginal role. The forest sector in Italy is characterized by a high institutional fragmentation and centralized decision-making processes dominated by Public Forest Administrations. Public participation in forest policy processes has been implemented since the 1990s at national, regional and local levels in several cases. However, today no significant changes have been observed in the overall governance of the forest sector and stakeholders' involvement in Italian forest policy decision-making is still rather limited. The aims of this paper are to describe the state of forest-related participatory processes in Italy at various levels (national, regional and local) and identify which factors and actors hinder or support the establishment and implementation of participatory forest-related processes in the country. The forest-related participatory processes are analyzed adopting a qualitative-based approach and interpreting interactive, complex and non-linear participatory processes through the lens of panarchy theory
Co-constructing a new framework for evaluating social innovation in marginalized rural areas
The EU funded H2020 project \u2018Social Innovation in Marginalised Rural Areas\u2019 (SIMRA; www.simra-h2020.eu) has the overall objective of advancing the state-of-the-art in social innovation. This paper outlines the process for co- developing an evaluation framework with stakeholders, drawn from across Europe and the Mediterranean area, in the fields of agriculture, forestry and rural development. Preliminary results show the importance of integrating process and outcome-oriented evaluations, and implementing participatory approaches in evaluation practice. They also raise critical issues related to the comparability of primary data in diverse regional contexts and highlight the need for mixed methods approaches in evaluation
The role of dark matter in the galaxy mass-size relationship
The observed relationship between stellar mass and effective radius for early
type galaxies, pointed out by many authors, is interpreted in the context of
Clausius' virial maximum theory. In this view, it is strongly underlined that
the key of the above mentioned correlation is owing to the presence of a deep
link between cosmology and the existence of the galaxy Fundamental Plane. Then
the ultimate meaning is: understanding visible mass - size correlation and/or
Fundamental Plane means understanding how galaxies form. The mass - size
relationship involves baryon (mainly stellar) mass and its typical dimension
related to the light, but it gets memory of the cosmological mass variance at
the equivalence epoch. The reason is that the baryonic component virializes by
sharing virial energy in about equal amount between baryons and dark matter,
this sharing depending, in turn, on the steepness of the dark matter
distribution. The general strategy consists in using the two-component tensor
virial theorem for determining the virialized baryonic configurations. A King
and a Zhao density profile are assumed for the inner baryonic and the outer
dark matter component, respectively, at the end of the relaxation phase. All
the considerations are restricted to spherical symmetry for simplicity. The
effect of changing the dark-to-baryon mass ratio, m, is investigated inside a
LambdaCDM scenario. A theoretical mass - size relation is expressed for the
baryonic component, which fits fairly well to the data from a recently studied
galaxy sample. Finally, the play of intrinsic dispersion on the mass ratio, m,
is discussed in the light of the cusp/core problem and some consequences are
speculated about the existence of a limit, m_l, expected by the theory.Comment: 36 pages, 8 figures (Accepted for publication in New Astronomy
Dilatonic Black Holes, Naked Singularities and Strings
We extend a previous calculation which treated Schwarschild black hole
horizons as quantum mechanical objects to the case of a charged, dilaton black
hole. We show that for a unique value of the dilaton parameter `a', which is
determined by the condition of unitarity of the S matrix, black holes transform
at the extremal limit into strings.Comment: 8 pages, REVTE
Component-based Geometry Manipulation for Aerodynamic Shape Optimization with Overset Meshes
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143082/1/6.2017-3327.pd
Caesalpinieae (Leguminosae-Caesalpinioideae) do campo experimental da Embrapa Amazônia Oriental, municÃpio de Moju, PA, Brasil.
(Caesalpinieae (Leguminosae-Caesalpinioideae) do Campo Experimental da Embrapa Amazônia Oriental, MunicÃpio de Moju, PA, Brasil). Este trabalho tem como objetivo realizar o estudo florÃstico-taxonômico da tribo Caesalpinieae, do Campo Experimental da Embrapa Amazônia Oriental, Moju, PA, complementando o conhecimento da flora local, cujo inventário teve inÃcio em 2001; visa também contribuir para o conhecimento das Leguminosae do Estado do Pará. As coletas foram feitas através de técnicas convencionais utilizadas em taxonomia vegetal. A identificação dos espécimes foi realizada, inicialmente, nos herbários IAN e MG, comparando-se com material previamente determinado; a seguir, utilizou-se literatura especÃfica e comparação com os tipos. Caesalpinieae está representada na área por 10 táxons, dos quais Batesia, Campsiandra, Dimorphandra, Libidibia e Vouacapoua apresentam apenas uma espécie cada; Tachigali está representado por cinco espécies. Dimorphandra macrostachya ssp. congestiflora é um novo registro para o Estado do Pará. Neste trabalho são apresentadas descrições e chave para identificação dos táxons estudados, ilustrações detalhadas, área de ocorrência, lista do material examinado e comentários sobre cada táxon tratado
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