The Phoenix Deep Survey: The 1.4 GHz microJansky catalogue

The initial Phoenix Deep Survey (PDS) observations with the Australia Telescope Compact Array have been supplemented by additional 1.4 GHz observations over the past few years. Here we present details of the construction of a new mosaic image covering an area of 4.56 square degrees, an investigation of the reliability of the source measurements, and the 1.4 GHz source counts for the compiled radio catalogue. The mosaic achieves a 1-sigma rms noise of 12 microJy at its most sensitive, and a homogeneous radio-selected catalogue of over 2000 sources reaching flux densities as faint as 60 microJy has been compiled. The source parameter measurements are found to be consistent with the expected uncertainties from the image noise levels and the Gaussian source fitting procedure. A radio-selected sample avoids the complications of obscuration associated with optically-selected samples, and by utilising complementary PDS observations including multicolour optical, near-infrared and spectroscopic data, this radio catalogue will be used in a detailed investigation of the evolution in star-formation spanning the redshift range 0 < z < 1. The homogeneity of the catalogue ensures a consistent picture of galaxy evolution can be developed over the full cosmologically significant redshift range of interest. The 1.4 GHz mosaic image and the source catalogue are available on the web at http://www.atnf.csiro.au/~ahopkins/phoenix/ or from the authors by request.Comment: 16 pages, 11 figures, 4 tables. Accepted for publication by A

Stress ocupacional e afrontamento em oficiais da polícia militar portuguesa

This study describes the professional experience of military police officers from the Portuguese Republican National Guard (N = 95). We focused on the main sources and consequences of stress and the coping strategies used to deal with stress. The evaluation protocol included one closed-ended question and four open-ended questions. Data analysis of meaningful text segments was conceptually based and data categorization followed deductive content analysis. Results allowed the identification of 483 meaning units. Factors intrinsic to the job and the relationships at work were the main stressors referred by participants. The consequences of stressors were evident at an individual level, affecting family, psychological, and physical/health domains. The coping strategies used to deal with the main source of stress in the professional career were focused on problem solving (e.g., active confrontation) and emotional regulation (e.g., situation acceptance). Practical implications and future avenues of research with these professionals are discussed.Este estudio analiza la experiencia profesional de agentes de la policía militar de la Guarda Nacional Republicana portuguesa (N = 95). Se centró en las principales fuentes y consecuencias del estrés, así como en las estrategias de afrontamiento. El protocolo de evaluación incluyó una pregunta cerrada y cuatro abiertas. Se realizó una categorización de datos atendiendo a un análisis de contenido deductivo. Las respuestas permitieron establecer 483 unidades de significado, a partir de las cuales se identificaron las principales quejas, relacionadas con factores intrínsecos al trabajo y a las relaciones interpersonales. Las consecuencias de estos problemas fueron evidentes en el plano individual (psicológicas y de salud física) y también afectaban a la familia. Las habilidades utilizadas para hacer frente a las principales fuentes de estrés estaban centradas en la resolución de problemas y el control emocional. Se discuten las implicaciones prácticas y las futuras vías de investigación con estos profesionales.Este estudo analisa a experiência profissional de agentes da polícia militar da Guarda Nacional Republicana Portuguesa (N=95). Centramo-nos nas principais fontes e consequências do stress assim como nas estratégias de afrontamento. O protocolo de avaliação incluiu uma pergunta fechada e quatro abertas. Realizou-se uma categorização de dados atendendo a uma análise de conteúdo dedutivo. As respostas permitiram a identificação de 483 unidades de significado, a partir das quais se identificaram as principais queixas. Estas estavam relacionadas com fatores intrínsecos ao trabalho e relações interpessoais. As consequências destes problemas foram evidentes no nível individual (psicológicas e saúde física) afetando também à família. As habilidades utilizadas para fazer frente às principais fontes de stress estavam centradas na resolução de problemas e o controle emocional. Discutem-se as implicações práticas e as futuras vias de pesquisa com estes profissionais.This study was conducted at Psychology Research Centre, University of Minho, and supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds and when applicable co-financed by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013)

On the Determination of Star Formation Rates in Evolving Galaxy Populations

The redshift dependence of the luminosity density in certain wavebands (e.g. UV and H-alpha) can be used to infer the history of star formation in the populations of galaxies producing this luminosity. This history is a useful datum in studies of galaxy evolution. It is therefore important to understand the errors that attend the inference of star formation rate densities from luminosity densities. This paper explores the self-consistency of star formation rate diagnostics by reproducing commonly used observational procedures in a model with known galaxy populations, evolutionary histories and spectral emission properties. The study reveals a number of potential sources of error in the diagnostic processes arising from the differential evolution of different galaxy types. We argue that multi-wavelength observations can help to reduce these errors.Comment: 13 pages (including 5 encapsulated postscript figures), aastex, accepted for publication in Ap

Direct Detection of Giant Close-In Planets Around the Source Stars of Caustic-Crossing Microlensing Events

We propose a direct method to detect close-in giant planets orbiting stars in the Galactic bulge. This method uses caustic-crossing binary microlensing events discovered by survey teams monitoring the bulge to measure light from a planet orbiting the source star. When the planet crosses the caustic, it is more magnified than the source star; its light is magnified by two orders of magnitude for Jupiter size planets. If the planet is a giant close to the star, it may be bright enough to make a significant deviation in the light curve of the star. Detection of this deviation requires intensive monitoring of the microlensing light curve using a 10-meter class telescope for a few hours after the caustic. This is the only method yet proposed to directly detect close-in planets around stars outside the solar neighborhood.Comment: 4 pages, 2 figures. Submitted to ApJ Letter

Rail power conditioner based on indirect AC/DC/AC modular multilevel converter using a three-phase V/V power transformer

This paper presents a rail power conditioner (RPC) system based on an indirect AC/DC/AC modular multilevel converter (MMC) where a V/V power transformer is used to feed the main catenary line and the locomotives. The proposed control strategy for this system has been introduced to guarantee a good compensating performance of negative sequence currents (NSCs) and harmonics on the public grid side. This control strategy has also the ability to achieve balanced and equal voltage between the MMC’s submodules (SMs) capacitors. Simulation results for this RPC based on an indirect MMC are presented in this paper to show the main advantages of using this topology. The results show how the proposed system is able to compensate NSCs and harmonics on the public grid side when the V/V power transformer feeds two unequal load sections.Fundação para a Ciência e Tecnologia (FCT)info:eu-repo/semantics/publishedVersio

Subcutaneous Sarcoidosis. A Rare Case of Specific Cutaneous Involvement

A sarcoidose é uma doença granulomatosa multissistémica de etiologia desconhecida. O envolvimento cutâneo pode ocorrer, sendo classificado de específico ou inespecífico, dependendo da presença ou ausência de granulomas no exame histopatológico da pele. A forma subcutânea é uma forma particular e mais rara de apresentação e constitui o único subtipo que se crê estar associado a doença sistémica

MACHO Mass Determination Based on Space Telescope Observation

We investigate the possibility of lens mass determination for a caustic crossing microlensing event based on a space telescope observation. We demonstrate that the parallax due to the orbital motion of a space telescope causes a periodic fluctuation of the light curve, from which the lens distance can be derived. Since the proper motion of the lens relative to the source is also measurable for a caustic crossing event, one can find a full solution for microlensing properties of the event, including the lens mass. To determine the lens mass with sufficient accuracy, the light curve near the caustic crossing should be observed within uncertainty of $\sim$ 1%. We argue that the Hubble Space Telescope observation of the caustic crossing supplied with ground-based observations of the full light curve will enable us to determine the mass of MACHOs, which is crucial for understanding the nature of MACHOs.Comment: 9 pages + 3 figures, accepted for publication in ApJ Letter

Short- and long-run determinants of sovereign debt credit ratings

We study the determinants of sovereign debt ratings from the three main international rating agencies, for the period 1995-2005. Using linear and ordered response models we employ a specification that allows us to distinguish between short and long-run effects, on a country’s rating, of macroeconomic and fiscal variables. The results point to a good performance of the models in explaining a country’s rating, both across agencies and time. Changes in GDP per capita, GDP growth, government debt, and government balance have a short-run impact on a country’s credit rating, while government effectiveness, external debt, foreign reserves and default history are important long-run determinants

O efeito “dominó” na Interacção Homem-Computador

A colaboração multidisciplinar é essencial para uma interacção homem-computador (IHC) efectiva. Historicamente a ciência dos computadores, a psicologia e as ciências sociais actuavam como disciplinas independentes, mas com o aumento da frequência na utilização das tecnologias da informação e comunicação em vários aspectos do dia-a-dia, a funcionalidade e acessibilidade assumiram uma importância cada vez maior. Neste artigo é apresentada uma reflexão sobre a multidisciplinaridade e transversalidade da IHC em termos tecnológicos e tendências futuras

Optimal Microlensing Observations

One of the major limitations of microlensing observations toward the Large Magellanic Cloud (LMC) is the low rate of event detection. What can be done to improve this rate? Is it better to invest telescope time in more frequent observations of the inner high surface-brightness fields, or in covering new, less populated outer fields? How would a factor 2 improvement in CCD sensitivity affect the detection efficiency? Would a series of major (factor 2--4) upgrades in telescope aperture, seeing, sky brightness, camera size, and detector efficiency increase the event rate by a huge factor, or only marginally? I develop a simplified framework to address these questions. With observational resources fixed at the level of the MACHO and EROS experiments, the biggest improvement (factor ~2) would come by reducing the time spent on the inner ~25 deg^2 and applying it to the outer ~100 deg^2. By combining this change with the characteristics of a good medium-size telescope (2.5 m mirror, 1" point spread function, thinned CCD chips, 1 deg^2 camera, and dark sky), it should be possible to increase the detection of LMC events to more than 100 per year (assuming current estimates of the optical depth apply to the entire LMC).Comment: Submitted to ApJ, 13 pages plus 3 figure