7,798 research outputs found
Trade Policy and Factor Prices: An Empirical Strategy
This paper presents a new empirical strategy for estimating the effects of trade policy on domestic factor prices when policy endogeneity is suspected. Absent income effectson factor supplies or domestic prices, the coefficient on the terms of trade can provide an unbiased estimator of the effect of trade barriers on the factor distribution of income for a small economy. In the more general case where income effects are allowed for, we provide a means to quantify and control for the possible bias. We implement our strategy on a cross-national data set of trade policies and income shares of capital and labor. We find little evidence of the existence of Stolper-Samuelson effects, both for the sample as a whole as well as within cones of diversification. Consistent with a model of wage bargaining, we find that the effect of openness on capital shares is greater for countries with higher unionization rates.Factor prices, trade policy, Stolper-Samuelson theorem, wage bargaining
Freed from Illiteracy? A Closer Look at Venezuela’s Robinson Literacy Campaign
We evaluate the success of the Venezuelan government’s latest nationwide literacy program, Misión Robinson, using official Venezuelan government survey data. Controlling for existing trends in literacy rates by age groups over the period 1975 to 2005, we find at most a small positive effect of Robinson on literacy rates, and in many specifications the program impact is statistically indistinguishable from zero. This main result is robust to time series analysis by birth cohort, and to state-level difference-in-differences estimation. The results appear to be inconsistent with recent official claims of the complete eradication of illiteracy in Venezuela, but resonate with existing research on other adult literacy programs, which have usually been expensive failures.
Brighter Branes, enhancement of photon production by strong magnetic fields in the gauge/gravity correspondence
We use the gauge/gravity correspondence to calculate the rate of photon
production in a strongly coupled N=4 plasma in the presence of an intense
magnetic field. We start by constructing a family of back reacted geometries
that include the black D3-brane solution, as a smooth limiting case for B=0,
and extends to backgrounds with an arbitrarily large constant magnetic field.
This family provides the gravitational dual of a field theory in the presence
of a very strong magnetic field which intensity can be fixed as desired and
allows us to study its effect on the photon production of a quark-gluon plasma.
The inclusion of perturbations in the electromagnetic field on these
backgrounds is consistent only if the metric is perturbed as well, so we use
methods developed to treat operator mixing to manage these general
perturbations. Our results show a clear enhancement of photon production with a
significant anisotropy, which, in qualitative agreement with the experiments of
heavy ion collisions, is particularly noticeable for low P.Comment: This paper was replaced including metric perturbations for
consistency of the calculation, and reports important qualitative changes. 43
page
Fuzzy Predictive Controller for Mobile Robot Path Tracking
IFAC Intelligent Components and Instruments for Control Applications, Annecy, France 1997This paper presents a way of implementing a Model Based Predictive Controller (MBPC) for mobile robot path-tracking. The method uses a non-linear model of mobile robot dynamics and thus allows an accurate prediction of the future trajectories. Constraints on the maximum attainable angular velocity is also considered by the algorithm. A fuzzy approach is used to implement the MBPC. The fuzzy controller has been trained using a lookup-table scheme, where the database of fuzzy-rules has been obtained automatically from a set of input-output training patterns, computed with the predictive controller. Experimental results obtained when applying the fuzzy controller to a TRC labmate mobile platform are given in the paper.Ministerio de Ciencia y Tecnología TAP95-0307Ministerio de Ciencia y Tecnología TAP96-884C
About Helices and Solvents: VCD and more
Intermolecular forces drive self-organization of molecules, which is ultimately the origin of most the physical and chemical phenomena in Nature. Molecules able to interact themselves by non-covalent forces, as hydrogen bonding and/or hydrophobic attractions, usually form macrostructures in condensed phases (solid, solution). The properties of these aggregates depend of three main factors: the structural and chemical features of the molecules, the nature of intermolecular forces and the environment. The first two drive aggregation in solid state, while in solution the role of the solvent become determinant as it can induce a variety of structural effects on the aggregation behaviour of the solute. In the case of chiral molecules, this property is transferred to the aggregates and supramolecular chirality appears.
Here we present our research on chiral molecules that self-organize in solution forming helical structures. We use VCD as the main chiroptical tool, but also supported by other chiroptical spectroscopies (ECD, ROA) and theoretical modelling. In our first steps, we studied the effect of modulating the environmental settings on the helices. Thus, helix handedness was proved highly and reversibly dependent on factors as pH or ionic strength in peptide-mimetic hydrogelators. We also observe how the initial conditions (concentration, temperature) were capable of controlling the helix structure of oligo-p-phenylene-based polymers towards kinetic or thermodynamics pathways. Besides, the structure of the helices can also be the consequence of direct solvent-solute interactions. In this way, we have demonstrated that an achiral solvent can act as a template for chiral organization of N-heterotriangulenes-based organogelators, thus showing the different levels of complexity of the hierarchical organization of supramolecular polymers.
But the solvent-helix interactions can be bidirectional. As a nice example, we recorded chiral signals which can be only assigned to the organization of the solvent molecules around helical aggregates of phenylglycine functionalized poly(phenylacetylene)s. The solvent molecules thus form a first solvation shell to which the helix chirality is transferred. The helices would act therefore as a template of the solvent molecules, and the chirality of this external helix would be fully controlled by the solute.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
El fin del plazo para adaptarse al Grado, las sentencias judiciales sobre su aplicación y análisis desde el punto de vista de la actividad de las Defensorías (Reflexiones en base a sentencias)
De acuerdo con la disposición transitoria segunda del Real Decreto 1393/2007, el
30 de Septiembre de 2017 es la fecha tope para que las universidades españolas puedan realizar exámenes que permitan a los alumnos de las antiguas titulaciones finalizar sus
estudios sin la necesidad de tener que adaptarse a la estructura del Grado.
Hasta el presente momento, en general, las universidades han permitido la
realización de al menos cuatro convocatorias en los dos cursos posteriores a la
finalización oficial de la impartición de las enseñanzas de diplomado o licenciado, algo
que algunos defensores hemos entendido equivocado pues creíamos que, teniendo como
premisa el cumplimiento de las normas de progreso y permanencia, la citada disposición
transitoria segunda no obliga a ello.
En el presente año 2016 se han hecho públicos los fallos de dos tribunales de lo
Contencioso-Administrativo que hacen una interpretación radicalmente opuesta de la
norma lo que, a nuestro juicio, lejos de aclarar o facilitar la toma de decisiones respecto
a la manera en la que debe aplicarse la citada disposición transitoria, genera una situación
cuyo alcance se nos escapa a vislumbrar. En concreto, mientras una de ellas estima que
los estudiantes tienen la posibilidad de ser evaluados hasta septiembre de 2017, la otra
establece el límite de los dos años posteriores a la de la finalización oficial de cada uno
de los estudios.
En el presente artículo se pretende hacer unas breves reflexiones sobre los motivos
que han conducido a pronunciarnos a favor de los estudiantes que reclaman la posibilidad
de realizar exámenes de las asignaturas pendientes hasta septiembre de 2017
Calibrating the Na\"ive Cornell Model with NRQCD
Along the years, the Cornell Model has been extraordinarily successful in
describing hadronic phenomenology, in particular in physical situations for
which an effective theory of the strong interactions such as NRQCD cannot be
applied. As a consequence of its achievements, a relevant question is whether
its model parameters can somehow be related to fundamental constants of QCD. We
shall give a first answer in this article by comparing the predictions of both
approaches. Building on results from a previous study on heavy meson
spectroscopy, we calibrate the Cornell model employing NRQCD predictions for
the lowest-lying bottomonium states up to NLO, in which the bottom mass is
varied within a wide range. We find that the Cornell model mass parameter can
be identified, within perturbative uncertainties, with the MSR mass at the
scale GeV. This identification holds for any value of or
the bottom mass, and for all perturbative orders investigated. Furthermore, we
show that: a) the "string tension" parameter is independent of the bottom mass,
and b) the Coulomb strength of the Cornell model can be related to the
QCD strong coupling constant at a characteristic non-relativistic
scale. We also show how to remove the renormalon of the static QCD
potential and sum-up large logs related to the renormalon subtraction by
switching to the low-scale, short-distance MSR mass, and using R-evolution. Our
R-improved expression for the static potential remains independent of the heavy
quark mass value and agrees with lattice QCD results for values of the radius
as large as fm, and with the Cornell model potential at long distances.
Finally we show that for moderate values of , the R-improved NRQCD and
Cornell static potentials are in head-on agreement.Comment: 22 pages, 13 figures, 3 table
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