219 research outputs found
Necessary and sufficient optimality conditions for optimization problems in function spaces and applications to control theory
We consider an abstract formulation for optimization problems in some Lp spaces. The variables are restricted by pointwise upper and lower bounds and by finitely many equality and inequality constraints of functional type. Second-order necessary and sufficient optimality conditions are established, where the cone of critical directions is arbitrarily close to the form which is expected from the optimization in finite dimensional spaces. The results are applied to an optimal control problem governed by a partial differential equation. Finally we compare the conditions obtained by applying this abstract procedure and those ones derived by using the methods adapted to the optimal control problem
La colaboración empresa-universidad en el ámbito de las razas ovinas autóctonas españolas: el ejemplo de Melovine
Se describe la colaboración establecida desde los años 90 hasta la actualidad
entre un laboratorio veterinario (CEVA Salud Animal) y una universidad
española (Universidad de Zaragoza), con la hormona pineal melatonina
como eje. Los objetivos fundamentales han sido la descripción de los mecanismos
básicos de actuación de esta hormona sobre la estacionalidad reproductiva
de la especie ovina y la realización de pruebas de campo en ganaderías
comerciales españolas, en un buen número de razas autóctonas, con
el fin de difundir los resultados obtenidos en condiciones reales de explotación.
Este hecho ha involucrado a todos los eslabones del sector ovino español,
desde el laboratorio, el ganadero, la cooperativa, el veterinario, las asociaciones
de defensa sanitaria, las administraciones públicas, las asociaciones
de razas, coordinados todos ellos por un departamento universitario. Se
ha trabajado con las razas autóctonas Castellana, Churra, Latxa, Manchega,
Merina, Ojalada, Ojinegra, Rasa Aragonesa, Ripollesa y Segureña, además
de otras como la Assaf y Lacaune. Se han descrito protocolos de uso de los
implantes de melatonina en ovejas adultas, corderas y moruecos, en distintos
momentos fisiológicos y sistemas de explotación. Todos ellos han sido
difundidos al sector ovino español a través de publicaciones científicas y técnicas
y a través de congresos, ponencias y cursos destinados a veterinarios
y ganaderos
Repercusiones de los ritmos reproductivos en un rebaño extensivo de raza manchega de carne
Se muestra la evolución de los resultados productivos en los últimos 22 años de una explotación de ovino de carne de la raza Manchega, destinado a la producción de lechazo, en función del sistema de cubriciones aplicado, el número de machos en cubrición y la utilización de melatonina para las cubriciones en épocas de anestro. Desde 1985 a 1992 se aplicaba en la explotación un sistema de tres partos en dos años. En 1993 se comenzó a utilizar el sistema STAR, de 5 cubriciones al año. En 2000 se aumentó el número de machos a más de un 5%. A partir de 2002 se comenzó a aplicar melatonina en las cubriciones que establece el sistema STAR en anestro estacionario (marzo y junio). Todas las modificaciones han mostrado beneficios en los resultados productivos. Los resultados de los últimos 5 años muestran la eficacia y la compatibilidad del sistema STAR en nuestras explotaciones de ovino en extensivo, acompañado de un número de machos importante que asegure buenas cubriciones (>5%). La aplicación de la melatonina optimiza este sistema de manejo, estabilizando las cubriciones de anestro, lo que hace que se produzca un mayor número de corderos útiles (vendidos + reposición), una venta de corderos mayor en el segundo semestre y se estabilicen los resultados entre años
Neutralino Dark Matter in BMSSM Effective Theory
We study thermal neutralino dark matter in an effective field theory
extension of the MSSM, called "Beyond the MSSM" (BMSSM) in Dine, Seiberg and
Thomas (2007). In this class of effective field theories, the field content of
the MSSM is unchanged, but the little hierarchy problem is alleviated by
allowing small corrections to the Higgs/higgsino part of the Lagrangian. We
perform parameter scans and compute the dark matter relic density. The light
Higgsino LSP scenario is modified the most; we find new regions of parameter
space compared to the standard MSSM. This involves interesting interplay
between the WMAP dark matter bounds and the LEP chargino bound. We also find
some changes for gaugino LSPs, partly due to annihilation through a Higgs
resonance, and partly due to coannihilation with light stops in models that are
ruled in by the new effective terms.Comment: 37 pages + appendi
Biodegradation kinetics of dissolved organic matter chromatographic fractions
Controls on the degradation of dissolved organic matter (DOM) are complex but key to understand the role of freshwaters in the carbon cycle. Both the origin and previous degradation history have been suggested to determine DOM reactivity, but it is still a major challenge to understand the links between DOM composition and biodegradation kinetics. An appropriate context to study these links are intermittent rivers, as summer drought naturally diversifies DOM sources and sinks. Here we investigated the biodegradation kinetics of DOM in the main aquatic environments present in a temporary river. During dark incubations we traced the dynamics of bulk DOM and its main chromatographic fractions defined using LC-OCD: high molecular weight substances (HMWS), low molecular weight substances (LMWS), and humic substances and building blocks. Bulk DOM decay patterns were successfully fitted to the reactivity continuum (RC) biodegradation model. The RC parameters depicted running waters as the sites presenting a more reactive DOM, and temporary pools, enriched in leaf litter, as the ones with slowest DOM decay. The decay patterns of each DOM fraction were consistent throughout sites. LMWS and HMWS decayed in all cases and could be modeled using the RC model. Notably, the dynamics of LMWS controlled the bulk DOM kinetics. We discuss the mechanistic basis for the chromatographic fractions' kinetics during biodegradation and the implications that preconditioning and summer drought can have for DOM biodegradation in intermittent rivers
One-loop Correction and the Dilaton Runaway Problem
We examine the one-loop vacuum structure of an effective theory of gaugino
condensation coupled to the dilaton for string models in which the gauge
coupling constant does not receive string threshold corrections. The new
ingredients in our treatment are that we take into account the one-loop
correction to the dilaton K\"ahler potential and we use a formulation which
includes a chiral field corresponding to the gaugino bilinear. We find
through explicit calculation that supersymmetry in the Yang-Mills sector is
broken by gaugino condensation.
The dilaton and field have masses on the order of the gaugino
condensation scale independently of the dilaton VEV. Although the calculation
performed here is at best a model of the full gaugino condensation dynamics,
the result shows that the one-loop correction to the dilaton K\"ahler potential
as well as the detailed dynamics at the gaugino condensation scale may play an
important role in solving the dilaton runaway problem.Comment: 19 page
Estudio comparativo de diferentes técnicas geofísicas para el control de la intrusión salina en acuíferos costeros: Aplicación al acuífero de Oued Laou (Marruecos)
Groundwater is a fundamental and strategic resource for water supply of coastal areas, especially in the Mediterranean basin where the irregularity of precipitation, both seasonally and year-onyear, put at risk the availability of surface water in the rivers, which go from being dry for long periods to causing torrential discharges. In particular, if the exploitation of coastal aquifers is not properly managed and the quality of groundwater is not monitored regularly, important sectors of the aquifer may be affected by saltwater intrusion, and cause the abandonment of the wells. Geophysical methods are a very effective complement to provide indirect information on groundwater salinity in areas of the aquifer where wells or piezometers are not available for sampling. This study presents the results obtained from the application of different geophysical methods in the coastal aquifer of Oued Laou (Morocco) as a complement to hydrochemical data. Four geophysical methods, two electrical: vertical electrical sounding and electrical resistivity tomography, and two electromagnetic: frequency domain EM and time domain EM sounding. The comparative analysis of the results obtained by each method has made it possible to assess the coherence and complementarity of each method, as well as their corresponding advantages and limitations in terms of resolution and cost-effectiveness
Model for a Universe described by a non-minimally coupled scalar field and interacting dark matter
In this work it is investigated the evolution of a Universe where a scalar
field, non-minimally coupled to space-time curvature, plays the role of
quintessence and drives the Universe to a present accelerated expansion. A
non-relativistic dark matter constituent that interacts directly with dark
energy is also considered, where the dark matter particle mass is assumed to be
proportional to the value of the scalar field. Two models for dark matter
pressure are considered: the usual one, pressureless, and another that comes
from a thermodynamic theory and relates the pressure with the coupling between
the scalar field and the curvature scalar. Although the model has a strong
dependence on the initial conditions, it is shown that the mixture consisted of
dark components plus baryonic matter and radiation can reproduce the expected
red-shift behavior of the deceleration parameter, density parameters and
luminosity distance.Comment: 11 pages and 6 figures. To appear in GR
Big Bang Nucleosynthesis with Gaussian Inhomogeneous Neutrino Degeneracy
We consider the effect of inhomogeneous neutrino degeneracy on Big Bang
nucleosynthesis for the case where the distribution of neutrino chemical
potentials is given by a Gaussian. The chemical potential fluctuations are
taken to be isocurvature, so that only inhomogeneities in the electron chemical
potential are relevant. Then the final element abundances are a function only
of the baryon-photon ratio , the effective number of additional neutrinos
, the mean electron neutrino degeneracy parameter , and
the rms fluctuation of the degeneracy parameter, . We find that for
fixed , , and , the abundances of helium-4,
deuterium, and lithium-7 are, in general, increasing functions of .
Hence, the effect of adding a Gaussian distribution for the electron neutrino
degeneracy parameter is to decrease the allowed range for . We show that
this result can be generalized to a wide variety of distributions for .Comment: 9 pages, 3 figures, added discussion of neutrino oscillations,
altered presentation of figure
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