Equivalence of reduced, Polyakov, Faddeev-Popov, and Faddeev path-integral quantization of gauge theories

A geometrical treatment of the path integral for gauge theories with first-class constraints linear in the momenta is performed. The equivalence of reduced, Polyakov, Faddeev-Popov, and Faddeev path-integral quantization of gauge theories is established. In the process of carrying this out we find a modified version of the original Faddeev-Popov formula which is derived under much more general conditions than the usual one. Throughout this paper we emphasize the fact that we only make use of the information contained in the action for the system, and of the natural geometrical structures derived from it.

BRST-invariant path integral for a spinning relativistic particle

The propagator of a relativistic spinning particle is calculated using the Becchi-Rouet-Stora-Tyutin-(BRST)-invariant path-integral formalism of Fradkin and Vilkovisky. The spinless case is considered as an introduction to the formalism.

Quantum decay of metastable states in small magnetic particles

We present an imaginary-time path-integral study of the problem of quantum decay of a metastable state of a uniaxial magnetic particle placed in the magnetic field at an arbitrary angle. Our findings agree with earlier results of Zaslavskii obtained by mapping the spin Hamiltonian onto a particle Hamiltonian. In the limit of low barrier, weak dependence of the decay rate on the angle is found, except for the field which is almost normal to the anisotropy axis, where the rate is sharply peaked, and for the field approaching the parallel orientation, where the rate rapidly goes to zero. This distinct angular dependence, together with the dependence of the rate on the field strength, provides an independent test for macroscopic spin tunneling.

Quantum-to-classical crossover in full counting statistics

The reduction of quantum scattering leads to the suppression of shot noise. In this Letter, we analyze the crossover from the quantum transport regime with universal shot noise to the classical regime where noise vanishes. By making use of the stochastic path integral approach, we find the statistics of transport and the transmission properties of a chaotic cavity as a function of a system parameter controlling the crossover. We identify three different scenarios of the crossover.

A survey on coverage path planning for robotics

Coverage Path Planning (CPP) is the task of determining a path that passes over all points of an area or volume of interest while avoiding obstacles. This task is integral to many robotic applications, such as vacuum cleaning robots, painter robots, autonomous underwater vehicles creating image mosaics, demining robots, lawn mowers, automated harvesters, window cleaners and inspection of complex structures, just to name a few. A considerable body of research has addressed the CPP problem. However, no updated surveys on CPP reflecting recent advances in the field have been presented in the past ten years. In this paper, we present a review of the most successful CPP methods, focusing on the achievements made in the past decade. Furthermore, we discuss reported field applications of the described CPP methods. This work aims to become a starting point for researchers who are initiating their endeavors in CPP. Likewise, this work aims to present a comprehensive review of the recent breakthroughs in the field, providing links to the most interesting and successful works

El pluralisme mèdic: una clau interpretativa per a una història integral de la medicina

El recurs als professionals sanitaris es sols una part de totes aquelles iniciatives, actuacions o creences que els nostres avantpassats van desenvolupar per conservar o millorar la salut, prevenir la malaltia o recuperar la salut. El recurs a altres tipus d'instàncies assistencials o terapèutiques, que es coneix com "pluralisme assistencial", sol ser la norma més que l'excepció. Per a enfocar adequadament aquest problema, cal centrar la indagació històrica sobre aquells -les persones malaltes o sanes- que volien i buscaven la salut. Aquests tipus d'acostaments pretenen tenir en compte totes les possibilitats a les quals es va recórrer en el passat per tal d'afrontar els problemes de salut.

Two algorithms to find a power integral basis

"Vegeu el resum a l'inici del fitxer adjunt."

Stable rank of leavitt path algebra

We characterize the values of the stable rank for Leavitt path algebras, by giving concrete criteria in terms of properties of the underlying graph.

Turkey's accession to the EU: interests, ideas and path dependence

The paper is divided into four sections. The first offers a critical assessment of explanations of both rationalist and constructivist approaches currently dominating European studies and assesses the notion of path dependence. The second and third sections analyse the role of both material interests and polity ideas in EU enlargement to Turkey, and conclude that explanations exclusively based on either strategic calculations or values and identities have significant shortcomings. The fourth section examines the institutional path of Turkey's candidacy to show how the course of action begun at Helsinki restricted the range of possible and legitimate options three years later in Copenhagen.

Chain conditions for Leavitt path algebras

In this paper, results known about the artinian and noetherian conditions for the Leavitt path algebras of graphs with finitely many vertices are extended to all row-finite graphs. In our first main result, necessary and sufficient conditions on a row-finite graph E are given so that the corresponding (not necessarily unital) Leavitt path K-algebra L(E) is semisimple. These are precisely the algebras L(E)for which every corner is left (equivalently, right)artinian. They are also precisely the algebras L(E) for which every finitely generated left (equivalently, right) L(E)-module is artinian. In our second main result, we give necessary and sufficient conditions for every corner of L(E) to be left (equivalently, right) noetherian. They also turn out to be precisely those algebras L(E) for which every finitely generated left(equivalently, right) L(E)-module is noetherian. In both situations, isomorphisms between these algebras and appropriate direct sums of matrix rings over K or K[x, x−1] are provided. Likewise, in both situations, equivalent graph theoretic conditions on E are presented.

The Difficult and tortuous path of agricultural cooperative networks in spain, 1890-1935

The rural associationism developed from the last decades of the XIX century could be consider as an answer of the agriculturists to the increasing integration of agriculture in the market, and to the effects of the Great Depression. In the case of Spain, the initiatives in this sense arose with certain delay in relation to the countries of Western Europe. The beginning of the Spanish cooperativism is closely bound to the Law of 1906. It granted the agrarian cooperatives with fiscal exemptions and other types of supports to the associates, although the process did not really accelerate until the promulgation of the law regulation in 1908.

La Accesibilidad universal en los municipios: guía para una política integral de promoción y gestión

Conscientes de las complejidades que presenta la organización administrativa local y la diversidad que caracteriza a los Ayuntamientos de España, y lejos de querer establecer fórmulas mágicas o generalizar soluciones, con esta Guía se pretende aportar ideas útiles mediante propuestas y algunos ejemplos; con ella se quiere ayudar a promover distintas intervenciones a favor de la accesibilidad en los municipios. En este sentido, esta Guía pretende ser soporte para desarrollar una nueva etapa de intervención municipal en accesibilidad, que vaya más allá de la mera supresión de barreras y se prevenga su creación. Las medidas que se desarrollan son posibles vías para que los gobiernos locales puedan gestionar y promocionar de forma eficaz la accesibilidad en el municipio y así establecer una base sobre la cual todos los ciudadanos puedan desarrollar sus libertades individuales plenamente.

La Accesibilidad en España. Diagnóstico y bases para un plan integral de supresión de barreras. Libro verde

Este Libro Verde pretende difundir, compartir y discutir públicamente la situación de la accesibilidad en España, así como los instrumentos y políticas puestos en marcha en los últimos años para su promoción y las necesarias reformas o iniciativas para avanzar en el proceso de supresión de todo tipo de barreras –arquitectónicas, urbanísticas, en el transporte, la comunicación e información, etc.– en nuestro país.

Sistema de Informació i Gestió Integral de la Producció Pesquera Internacional (SIGIPPI)

Des de la ciència geogràfica combinada amb el coneixement biològic i comercial, aquest projecte pretén crear una eina basada en la biogeografia i les últimes tecnologies de la Informació Geogràfica, que permetrà a l’usuari disposar de informació actualitzada per cada espècie amb interès comercial. El projecte es basa en el desenvolupament d’una aplicació web de consulta, entrada i actualització de dades referents a la producció pesquera internacional. Les eines utilitzades són les bases de dades MySQL i PostgreSQL i programació web amb html, php i javacript. Aquesta aplicació està pensada per ser accessible des de qualsevol ordinador amb connexió a internet i es subdivideix en tres sub-aplicacions. La primera sub-aplicació es basa en l’entrada d’espècies a partir de l’estructura taxonòmica. Partint de l’arbre taxonòmic, l’usuari té la possibilitat d’entrar, eliminar o modificar qualsevol tàxon o espècie. La segona subaplicació és una eina de digitalització cartogràfica on-line on l’usuari podrà marcar, eliminar o modificar sobre un mapa les localitzacions de les espècies que estiguin entrades en la sub-aplicació anterior. Finalment, la tercera sub-aplicació és una eina d’entrada de dades quinzenals referent als comportaments pel que fa tan a les dimensions com a les disponibilitats de pesca per cada espècie i localització.