8,414 research outputs found
Ethnic Concentration, Cultural Identity and Immigrant Self-Employment in Switzerland
Immigrant self-employment rates vary considerably across regions in Switzerland. Business ownership provides an alternative to wage labour, where immigrants have to face structural barriers such as the limited knowledge of the local language, or difficulties in fruitfully making use of their own human capital. Despite their historically high unemployment rates with respect to natives, immigrants in Switzerland are less entrepreneurial. It is therefore important to uncover factors that may facilitate the transition from the status of immigrant to the one of economic agent. Among others factors, concentration in ethnic enclaves, as well as accumulated labour market experience and time elapsed since immigration, have been associated to higher business ownership rates. In this paper, we use a cross-section of 2,490 Swiss municipalities in order to investigate the role played by the ethnic concentration of immigrants, as well as cultural factors, in determining self-employment rates.
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Integrity static analysis of COTS/SOUP
This paper describes the integrity static analysis approach developed to support the justification of commercial off-the-shelf software (COTS) used in a safety-related system. The static analysis was part of an overall software qualification programme, which also included the work reported in our paper presented at Safecomp 2002. Integrity static analysis focuses on unsafe language constructs and “covert” flows, where one thread can affect the data or control flow of another thread. The analysis addressed two main aspects: the internal integrity of the code (especially for the more critical functions), and the intra-component integrity, checking for covert channels. The analysis process was supported by an aggregation of tools, combined and engineered to support the checks done and to scale as necessary. Integrity static analysis is feasible for industrial scale software, did not require unreasonable resources and we provide data that illustrates its contribution to the software qualification programme
Interpolating the Sherrington-Kirkpatrick replica trick
The interpolation techniques have become, in the past decades, a powerful
approach to lighten several properties of spin glasses within a simple
mathematical framework. Intrinsically, for their construction, these schemes
were naturally implemented into the cavity field technique, or its variants as
the stochastic stability or the random overlap structures. However the first
and most famous approach to mean field statistical mechanics with quenched
disorder is the replica trick. Among the models where these methods have been
used (namely, dealing with frustration and complexity), probably the best known
is the Sherrington-Kirkpatrick spin glass: In this paper we are pleased to
apply the interpolation scheme to the replica trick framework and test it
directly to the cited paradigmatic model: interestingly this allows to obtain
easily the replica-symmetric control and, synergically with the broken replica
bounds, a description of the full RSB scenario, both coupled with several minor
theorems. Furthermore, by treating the amount of replicas as an
interpolating parameter (far from its original interpretation) this can be
though of as a quenching temperature close to the one introduce in
off-equilibrium approaches and, within this viewpoint, the proof of the
attended commutativity of the zero replica and the infinite volume limits can
be obtained.Comment: This article is dedicated to David Sherrington on the occasion of his
seventieth birthda
Características operacionais de um sistema de irrigação por Pivot Central.
Descrição do sistema de irrigação; Características operacionais do sistema da irrigação.bitstream/item/181083/1/FL-07347.pd
Metals recovery from spent Zn-MnO2 batteries by Hydrometallurgy
A hydrometallurgical process for recycling spent Zn-MnO2 batteries was developed, involving leaching with sulfuric acid, purification by precipitation and metals separation for further recovery. Leaching of zinc oxide was easily attained while for manganese oxide was rather difficult depending on temperature and acid concentration. At 90ºC and with the liquid/solid ratio of 20 L/kg, more than 95% of zinc is recovered in 30 minutes with 0.5M H2SO4. To attain similar recovery for manganese, higher levels of acid concentration and time are needed (e.g 0.7 M and 2 hours). After leaching a purification step is necessary to remove iron co-dissolved through Fe(III) precipitation. Separation of zinc from manganese by solvent extraction with 1M DEHPA follows in the process route. The countercurrent multistage separation diagram developed allows the production of a zinc electrolyte with 120 g/L Zn and 0.005 g/L Mn, and a raffinate with 16 g/L Mn and 0.013 g/L Zn
The mean field theory of spin glasses: the heuristic replica approach and recent rigorous results
The mathematically correct computation of the spin glasses free energy in the
infinite range limit crowns 25 years of mathematic efforts in solving this
model. The exact solution of the model was found many years ago by using a
heuristic approach; the results coming from the heuristic approach were crucial
in deriving the mathematical results. The mathematical tools used in the
rigorous approach are quite different from those of the heuristic approach. In
this note we will review the heuristic approach to spin glasses in the light of
the rigorous results; we will also discuss some conjectures that may be useful
to derive the solution of the model in an alternative way.Comment: 12 pages, 1 figure; lecture at the Flato Colloquia Day, Thursday 27
November, 200
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Safety justification frameworks: Integrating rule-based, goal-based and risk-informed approaches
The reliability and safety of the digital I&C systems that implement safety functions are critical issues. In particular, software defects could result in common cause failures that defeat redundancy and defence-in-depth mechanisms. Unfortunately, the differences in current safety justification principles and methods for digital I&C restrict international co-operation and hinder the emergence of widely accepted best practices. These differences also prevent cost sharing and reduction, and unnecessarily increase licensing uncertainties, thus creating a very difficult operating environment for utilities, vendors and regulatory bodies. The European project HARMONICS (Harmonised Assessment of Reliability of MOdern Nuclear I&C Software) is seeking to develop a more harmonised approach to the justification of software-based I&C systems important to safety. This paper outlines the justification framework we intend to develop in HARMONICS. It will integrate three strategies commonly used in safety justifications of I&C system and its software: rule-based-evidence of compliance to accepted standards; goal-based-evidence that the intended behaviour and other claimed properties has been achieved; and risk-informed-evidence that unintended behaviour is unlikely. The paper will present general forms of safety case that can be adapted to a variety of specific topics
On the stochastic mechanics of the free relativistic particle
Given a positive energy solution of the Klein-Gordon equation, the motion of
the free, spinless, relativistic particle is described in a fixed Lorentz frame
by a Markov diffusion process with non-constant diffusion coefficient. Proper
time is an increasing stochastic process and we derive a probabilistic
generalization of the equation . A
random time-change transformation provides the bridge between the and the
domain. In the domain, we obtain an \M^4-valued Markov process
with singular and constant diffusion coefficient. The square modulus of the
Klein-Gordon solution is an invariant, non integrable density for this Markov
process. It satisfies a relativistically covariant continuity equation
Estudio comparativo de dos métodos de radiografías forzadas para detectar la insuficiencia del ligamento cruzado anterior
En 32 pacientes con rotura unilateral de ligamento cruzado anterior (LCA) comprobada
mediante artroscopia se efectuó previamente una radiografía forzada de ambas rodillas
para estudiar el desplazamiento anterior de la tibia. Cada paciente fue estudiado mediante dos métodos
diferentes, Lachman activo radiológico (LAR) y TelosR. Se asumió el diagnóstico radiológico
de inestabilidad cuando la diferencia en el desplazamiento entre la rodilla lesionada y su control fue
superior a 3 mm. Los resultados demuestran que la diferencia media del desplazamiento entre la
rodilla lesionada y la normal fue superior a 3 mm con ambos métodos. En el lado interno 3,7 ±
3,7 mm con el LAR y 4,8 ± 5,8 mm con el Telos (diferencias no significativas). En el lado externo
esta diferencia fue de 4,3 ± 4,7 nun con el LAR y de 6,8 ± 6 mm con el Telos (p < 0,05). A pesar
de estos resultados, ambos métodos mostraron una sensibilidad para la detección de la insuficiencia
ligamentosa inferior al 70%, lo que cuestiona su valor para el diagnóstico de la misma.In a prospective study, 32 patients with arthroscopically proved anterior cruciate
ligament rupture were previously stressradiographied on both knees through two methods:
the quadriceps-contraction technique (QCT) and the TelosR device. Instability was
assumed when radiological differential displacement between injured and normal knee was greated
than 3 mm. Results showed that this differential displacement was greater than 3 mm with
both methods: 3,7 ± 3,7 mm v.s. 4,8 ± 5,8 mm in the medial side (differences not significant)
and 4,3 ± 4,7 mm v.s. 6,8 ± 6 mm (p < 0.05) for the lateral side with the QCT and TelosR respectively.
In spite of these differences, both methods showed a sensitivity lower than 70%
Thermodynamics and Universality for Mean Field Quantum Spin Glasses
We study aspects of the thermodynamics of quantum versions of spin glasses.
By means of the Lie-Trotter formula for exponential sums of operators, we adapt
methods used to analyze classical spin glass models to answer analogous
questions about quantum models.Comment: 17 page
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