13,479 research outputs found
The weight of matter
Einstein's traceless 1919 gravitational theory is analyzed from a variational
viewpoint. It is shown to be equivalent to a transverse (invariant only under
diffeomorphisms that preserve the Lebesgue measure) theory, with an additional
Weyl symmetry, in which the gauge is partially fixed so that the metric becomes
unimodular. In spite of the fact that this symmetry forbids direct coupling of
the potential energy with the gravitational sector, the equivalence principle
is recovered in the unimodular gauge owing to Bianchi's identities.Comment: LaTeX, 11 page
Few-body decay and recombination in nuclear astrophysics
Three-body continuum problems are investigated for light nuclei of
astrophysical relevance. We focus on three-body decays of resonances or
recombination via resonances or the continuum background. The concepts of
widths, decay mechanisms and dynamic evolution are discussed. We also discuss
results for the triple decay in connection with resonances and
density and temperature dependence rates of recombination into light nuclei
from -particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Modeling the thermal behavior of biosphere 2 in a non-controlled environment using bond graphs
Biosphere 2 is a closed ecological system of high complexity built to
deepen the understanding of ecological systems, to study the dynamics
of closed ecologies,
and to learn to control their behavior. The use of modeling and
simulation is crucial in the achievement of these goals. Understanding a
physical system is almost synonymous with possessing a model of its
comportment.
The main goal of this study is the development of a dynamic bond graph
model that represents the thermal behavior of the complex ecological system
under study, Biosphere 2. In this work, a first model that captures the
behavior of the ecological system in a non-controlled environment is
presented.Postprint (published version
A Change of Variables to the Dual and Factorization of Composite Anomalous Jacobians
Changes of variables giving the dual model are constructed explicitly for
sigma-models without isotropy. In particular, the jacobian is calculated to
give the known results. The global aspects of the abelian case as well as some
of those of the cases where the isometry group is simply connected are
considered.
Considering the anomalous case, we infer by a consistency argument that the
`multiplicative anomaly' should be replaceable by adequate rules for
factorization of composite jacobians. These rules are then generalized in a
simple way for composite jacobians defined in spaces of different types.
Implimentation of these rules then gives specific formulas for the anomally for
semisimple algebras and also for solvable ones.Comment: 15 pages, no figures, Latex file, A treatment of the global aspects
of the abelian and of semisimple duality groups are added. General formulas
for the mixed anomaly are derive
Softly Broken N=2 QCD with Massive Quark Hypermultiplets, I
We present a general analysis of all the possible soft breakings of N=2
supersymmetric QCD, preserving the analytic properties of the Seiberg-Witten
solutions for the SU(2) group with Nf=1, 2, 3 hypermultiplets. We obtain all
the couplings of the spurion fields in terms of properties of the
Seiberg-Witten periods, which we express in terms of elementary elliptic
functions by uniformizing the elliptic curves associated to each number of
flavors. We analyze in detail the monodromy properties of the softly broken
theory, and obtain them by a particular embedding into a pure gauge theory with
higher rank group. This allows to write explicit expressions of the effective
potential, which are close to the exact answer for moderate values of the
supersymmetry breaking parameters. The vacuum structures and phases of the
broken theories will be analyzed in the forthcoming second part of this paper.Comment: 35 pages, 3 figures, LaTeX file. Minor corrections in a few formulae,
typos correcte
Rudiments of Holography
An elementary introduction to Maldacena's AdS/CFT correspondence is given,
with some emphasis in the Fefferman-Graham construction. This is based on
lectures given by one of us (E.A.) at the Universidad Autonoma de Madrid.Comment: 60 pages, additional misprints corrected, references adde
Recursos gemorfológicos: evolución morfológica de las marmitas de erosión en el río Miño
5 páginas, 4 figuras.-- VII Simpósio Ibérico sobre a Bacia Hidrográfica do Rio Minho, Vilanova de Cerveira, 7-8 novembro 2014En el río Miño, que discurre en su mayor parte sobre granitos, se distinguen zonas en las que la
corriente circula directamente sobre la roca madre con formas características de erosión fluvial. Una de
las más comunes son las marmitas (potholes) que se van a generar en condiciones dependientes del
régimen hídrico y la estacionalidad del flujo del río. Junto a otras formas, las marmitas son parte del
patrimonio geomorfológico fluvial asociado al río Miño. En este estudio se presenta una secuenciación
evolutiva diferenciada en cuatro fases, para las cuales se han establecido valores umbral que marcan
cambios en la morfologíaPeer reviewe
Growth of sculpted forms in bedrock channels (Miño River, northwest Spain)
7 páginas, 4 tablas, 6 figurasA total of 216 sculpted forms were registered on the granitic bedrock of the Miño River,
northwest Iberian Peninsula. Analysis of in situ measurements (length, width and depth)
revealed three general type-sets: incipient forms, longitudinal furrows and circular pot-holes. Maximum depth and upper radius (at the incision surface) were identified as key variables to mathematically determine the growth rate in each set. Three regression models are presented revealing that the development of the forms depends on a power law explaining their size and shape. Morphological and dimensional thresholds were established to better identify stages from incipient active growth) and inherited (stationary growth) formsM.A.A.V. is supported by the Xunta de Galicia through the Plan Galego de investigación, innovación e crecemento 2011-2015 (Plan I2C) in collaboration with the International Campus do Mar (Predoc ED481A-2015/410)Peer reviewe
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