3,019 research outputs found
Financial Liberalization and Emerging Stock Market Volatility
In this paper we test whether volatility in six emerging markets has changed significantly over the period 1976:01-2002:03. This period corresponds to the years of more profound development of both the financial and the productive sides in emerging countries. We use alternative methodologies of of endogenous breakpoints detection that estimate the dates at which the behavior of the sotck market volatility changed. The analysis suggests that volatility has behaved in a di¤erent manner over the periodemerging markets, volatility, multiple structural breaks
Integrated cockpit for A-129
Weight, size, and mission requirements for the A-129 mandated an integrated system approach for the crew/cockpit interface design. Instead of the usual multitude of cockpit controls, indicators, gauges, and lights, the primary crew interface is a single multifunction keyboard and one or more multifunction CRT display units. This cockpit design approach imposed unusual constraints upon the system architecture to overcome the inherent information access limitations of a data input/output window that was restricted by the available space. The conceptual approach and resulting design of the A-129 cockpit with the intent to enhance the development of cockpit standardization are described
The Kirillov picture for the Wigner particle
We discuss the Kirillov method for massless Wigner particles, usually
(mis)named "continuous spin" or "infinite spin" particles. These appear in
Wigner's classification of the unitary representations of the Poincar\'e group,
labelled by elements of the enveloping algebra of the Poincar\'e Lie algebra.
Now, the coadjoint orbit procedure introduced by Kirillov is a prelude to
quantization. Here we exhibit for those particles the classical Casimir
functions on phase space, in parallel to quantum representation theory. A good
set of position coordinates are identified on the coadjoint orbits of the
Wigner particles; the stabilizer subgroups and the symplectic structures of
these orbits are also described.Comment: 19 pages; v2: updated to coincide with published versio
Monopole-based quantization: a programme
We describe a programme to quantize a particle in the field of a (three
dimensional) magnetic monopole using a Weyl system. We propose using the
mapping of position and momenta as operators on a quaternionic Hilbert module
following the work of Emch and Jadczyk.Comment: Contribution to the volume: Mathematical Physics and Field Theory,
Julio Abad, In Memoriam}, M. Asorey, J.V. Garcia Esteve, M.F. Ranada and J.
Sesma Editors, Prensas Universitaria de Zaragoza, (2009
Geometric Hamilton-Jacobi Theory
The Hamilton-Jacobi problem is revisited bearing in mind the consequences
arising from a possible bi-Hamiltonian structure. The problem is formulated on
the tangent bundle for Lagrangian systems in order to avoid the bias of the
existence of a natural symplectic structure on the cotangent bundle. First it
is developed for systems described by regular Lagrangians and then extended to
systems described by singular Lagrangians with no secondary constraints. We
also consider the example of the free relativistic particle, the rigid body and
the electron-monopole system.Comment: 40 page
Efectos de los temporales sobre las playas de la Bahía de Cádiz
[Resumen] En el presente trabajo se estudian los efectos que los temporales de Diciembre e 1995 y Enero de 1996 tuvieron sobre las playas de la Bahía de Cádiz. Del análisis del oleaje incidente se observa cómo sus efectos se multiplican cuando los picos de temporal coinciden con el máximo rango de mareas. Los cambios morfológicos registrados en las playas se estudian mediante el perfilamiento pre y post-temporal de playas tanto naturales como regeneradas artificialmente. La cuantificación de dichos cambios muestra cómo la forma inicial de los perfiles es determinante en el tipo de respuesta de las playas frente a olejaes de gran energía. También se manifiestan procesos de erosión en cordones dunares, mediante incisiones, desbordamientos, etc. La estimación final de los daños sufridos por las playas revela mayores pérdidas en aquellas zonas donde la presión antrópica es mayor[Abstract] The work deals with the effects that the storm surges of December-1995 and January-1996 made upon the beaches of Cádiz Bay (SW Spain). From the incidentwave analysis it can be deduced that the effects are much stronger when the surge peak coincides with maximum tidal ranges. The morphological changes recorded in the beaches are studied through pre- and post-surge profiling of both natural and artificially nourished beaches. The quantification of such morphological transformations shows that the initial beach profile is determinant in the kind of response of the beach to high wave-energy conditions. The erosive processes upon dune ridges are represented by gullying, overwashing, etc. The final estimation of losses in the beaches reveals higher damages in zones where anthropic preassure is higher
Geometric Hamilton-Jacobi Theory for Nonholonomic Dynamical Systems
The geometric formulation of Hamilton--Jacobi theory for systems with
nonholonomic constraints is developed, following the ideas of the authors in
previous papers. The relation between the solutions of the Hamilton--Jacobi
problem with the symplectic structure defined from the Lagrangian function and
the constraints is studied. The concept of complete solutions and their
relationship with constants of motion, are also studied in detail. Local
expressions using quasivelocities are provided. As an example, the nonholonomic
free particle is considered.Comment: 22 p
Consideraciones sobre el final del relleno endorreico de las fosas de Calatayud y Teruel y su paso al exorreísmo. Implicaciones morfoestratigráficas y estructurales
[Resumen] Se pone en evidencia como la edad de la Superficie de Erosión Fundamental y el
final del relleno endorreico de las fosas de Calatayud y Teruel, en la Cordillera Ibérica, no es un evento isócrono, sino variable en ambas depresiones yen. distintos sectores de una misma. La información geomorfológica y estratigráfica demuestra como la captura de una depresión endorreica y su paso al exorreismo es un proceso gradual en el espacio y en el tiempo, sin que necesariamente esté relacionado con estímulos tectónicos o climáticos. Así un intervalo de tiempo postcaptura puede estar representado en distintos sectores de una fosa por sedimentos
endorreicos, hiatos erosivos o de no depósito y depósitos aluviales exorreicos. Por otra parte se cuestiona la cronoestratigrafía tradicional de los mantos aluviales depositados en condiciones exorreicas. Finalmente se esboza la evolución espacio temporal de la captura y paso al exorreismo de las fosas de Calatayud y Teruel y de las semifosas pliocuaternarias del sector central de la Cordillera Ibérica.[Abstract] It is shown how the age of the "Fundamental Erosión Surface" and the end of the endorheic infill of Calatayud and Teruel grabens, in the Iberian Range, is not isochronous, but variable between both basins and among different sectors of a certain one. Both, geomorphological and stratigraphical evidences demonstrate how the capture of an endorheic basin and its transition to exorheic conditions is a gradual process, which not necessarily has to be related with tectonic or climatic factors. A po~t-capture time span may be represented in different sectors of a graben by endorheic sediments, erosional and nondepositional hiatus and alluvial exorheic deposits. On the other hand, the traditional chronostratigraphy of the alluvial fans deposited under exorheic conditions is argued. Finally, the space and time evolution of the capture and transition to exorheic conditions in Teruel and Calatayud grabens and in the Plioquaternary halfgrabens of the central sector of the Iberian range is outlined
Yacimientos de estaño del Oeste de España
[Resumen] En este trabajo se realiza una clasificación de los. yacimientos de estaño del oeste español basada, fundamentalmente, en consideraciones económicas. Tras una introducción explicativa de los objetivos y metodología empleados, así como una breve exposición del significado de las explotaciones de estaño españolas en el contexto mundial, se describen y clasifican los indicios y yacimientos más importantes, aportándose además un listado de la bibliografía específica más destacable[Abstract] This work presents a classification of the tin deposits in the westof Spain, based, mainly, on economic reasons. After an explaining introduction of the objetives and the method used, and a short exposition of the importance of spanish tin exploitations in the world context, the most important mines and occurrences are described and classified; in addition a list of the most relevant specific bibliography is given
On the ultraviolet behaviour of quantum fields over noncommutative manifolds
By exploiting the relation between Fredholm modules and the
Segal-Shale-Stinespring version of canonical quantization, and taking as
starting point the first-quantized fields described by Connes' axioms for
noncommutative spin geometries, a Hamiltonian framework for fermion quantum
fields over noncommutative manifolds is introduced. We analyze the ultraviolet
behaviour of second-quantized fields over noncommutative 3-tori, and discuss
what behaviour should be expected on other noncommutative spin manifolds.Comment: 10 pages, RevTeX version, a few references adde
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