2,868 research outputs found
Duration of Low Wage Employment: A Study Based on a Survival Model
This paper includes a survival analysis which attempts to explain the duration, as in the number of years a worker remains in a low wage situation. Explanatory variables take into account the characteristics of the employee, such as education, age, tenure with the company, gender and nationality, and the characteristics of the job and the company such as industry affiliation, number of employees, age of the company and location.low wage, survival, Portugal
The average longitudinal air shower profile: exploring the shape information
The shape of the extensive air shower (EAS) longitudinal profile contains information about the nature of the primary cosmic ray. However, with the current detection capabilities, the assessment of this quantity in an event-by-event basis is still very challenging. In this work we show that the average longitudinal profile can be used to characterise the average behaviour of high energy cosmic rays. Using the concept of universal shower profile it is possible to describe the shape of the average profile in terms of two variables, which can be already measured by the current experiments. These variables present sensitivity to both average primary mass composition and to hadronic interaction properties in shower development. We demonstrate that the shape of the average muon production depth profile can be explored in the same way as the electromagnetic profile having a higher power of discrimination for the state of the art hadronic interaction models. The combination of the shape variables of both profiles provides a new powerful test to the existing hadronic interaction models, and may also provide important hints about multi-particle production at the highest energies.Peer Reviewe
Cerenkov angle and charge reconstruction with the RICH detector of the AMS experiment
The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the
International Space Station (ISS) will be equipped with a proximity focusing
Ring Imaging Cerenkov (RICH) detector, for measurements of particle electric
charge and velocity. In this note, two possible methods for reconstructing the
Cerenkov angle and the electric charge with the RICH, are discussed. A
Likelihood method for the Cerenkov angle reconstruction was applied leading to
a velocity determination for protons with a resolution of around 0.1%. The
existence of a large fraction of background photons which can vary from event
to event, implied a charge reconstruction method based on an overall efficiency
estimation on an event-by-event basis.Comment: Proceedings submitted to RICH 2002 (Pylos-Greece
Basal-plane Incommensurate Phases in HCP Structures
An Ising model with competing interaction is used to study the appearance of
incommensurate phases in the basal plane of an hexagonal closed-packed
structure. The calculated mean-field phase diagram reveals various
1q-incommensurate and lock-in phases. The results are applied to explain the
basal-plane incommensurate phase in some compounds of the A'A"BX_4 family, like
K_2MoO_4, K_2WO_4, Rb_2WO4 and to describe the sequence of high-temperature
phase transitions in other compounds of this family.Comment: 8 pages, RevTeX + 4 ps figure
Programação de servidor de mapas para disponibilização de dados geográficos multidisciplinares utilizando tecnologias livres.
A crescente utilização de geotecnologias, e consequente elaboração de bases cartográficas, vem demandando a implementação de ferramentas para acesso dinâmico e interativo às informações organizadas. Servidores de mapas possibilitam a integração de informações geográficas representadas por mapas temáticos, imagens de satélite, fotografias aéreas ortorretificadas, e modelos 3D ou de realidade virtual georreferenciados. Nesse contexto, o presente trabalho apresenta procedimentos adotados para a programação do servidor de mapas desenvolvido para facilitar o acesso a informações georreferenciadas disponibilizadas no GeoPortal da Embrapa Milho e Sorgo. O servidor de mapas permite o acesso a bases cartográficas digitais na internet de forma interativa e dinâmica, utilizando software livres, considerando as plataformas Windows e Linux e possibilitando a integração espacial de informações geográficas multidisciplinares provenientes de diferentes fontes e formatos.bitstream/item/95877/1/doc-158.pd
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