The soft X-ray background towards the northern sky. A detailed analysis of the Milky Way halo

We present a correlation analysis of the diffuse X-ray background emission of the ROSAT all-sky survey with the Leiden/Dwingeloo 21-cm HI line survey. We derive a consistent model for the diffuse X-ray background emission over about 50% of the sky. Only three diffuse X-ray components are necessary to fit the ROSAT data from 0.1 keV to 2.4 keV: a) the Local Hot Bubble, b) the Milky Way Halo, and c) the extragalactic X-ray background. Only one temperature of the hot coronal gas in the Milky Way Halo is needed. Our model predicts, that a major fraction of the 1/4 keV and about 50% of the 3/4 keV diffuse X-ray emission originates from the Milky Way Halo. We detect a difference between the intensities towards the Galactic center and its anti-center, which is consistent with the electron density distribution independently derived from pulsar dispersion measurements.Comment: Astron. Nachr. in press, issue dedicated to the proceedings of the workshop "X-ray Surveys in the light of New Observatories", Sep. 2002, Santander, Spai

XMM-Newton Data Processing for Faint Diffuse Emission: Proton Flares, Exposure Maps and Report on EPIC MOS1 Bright CCDs Contamination

We present a study of the in-flight performance of the XMM-Newton EPIC MOS and pn detectors, with focus on the influence of proton flares and vignetting on the data. The very wide range in the conditions of our sample of observations, in terms of exposure length and background intensities, allows the detection of a wide range in the spectra of the proton flares, in contrast to the hard-spectrum flares proposed by Lumb et al.(2002) or Read et al.(2003) We also find an up to now unreported contamination in the low energy regime (E<0.5 keV) of the MOS1 observations, consisting of a significant increase in the measured intensities in two CCDs at the edges of the detector. This contamination yields in "bright CCDs" in the observations. Its effect must be taken into account for the study of sources detected in the affected CCDs. With respect to vignetting, we present in-flight exposure maps and we propose a method to repeat this calculation for user-definable energy bands. All the results presented here, have the goal to enable the study of very faint extended sources with XMM-Newton, like nearby galactic X-ray halos or the soft X-ray background.Comment: 18 pages, 11 figures, accepted for publication in A&A. Figures 10 and 11 accessible via http://www.astro.uni-bonn.de/~jpradas

The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files

We describe in detail the nature of XMM-Newton EPIC background and its various complex components, summarising the new findings of the XMM-Newton EPIC background working group, and provide XMM-Newton background blank sky event files for use in the data analysis of diffuse and extended sources. Blank sky event file data sets are produced from the stacking of data, taken from 189 observations resulting from the Second XMM-Newton Serendipitous Source Catalogue (2XMMp) reprocessing. The data underwent several filtering steps, using a revised and improved method over previous work, which we describe in detail. We investigate several properties of the final blank sky data sets. The user is directed to the location of the final data sets. There is a final data set for each EPIC instrument-filter-mode combination.Comment: Paper accepted by A&A 22 December 2006. 14 pages, 8 figures. Paper can also be found at http://www.star.le.ac.uk/~jac48/publications

Os roedores das ilhas Flores e Corvo : distribuição, fertilidade e morfometria

XIII Expedição Científica do Departamento de Biologia - Flores e Corvo 2007.O conhecimento da biologia e ecologia das espécies de roedores dos Açores é escasso. Integrado na XIII Expedição Científica do Departamento de Biologia da Universidade dos Açores, realizámos uma amostragem de roedores em três habitats distintos (pastagem, floresta e lixeira) na ilha das Flores, durante três noites, e num habitat (lixeira) na ilha do Corvo, durante uma noite. A espécie Mus musculus foi capturada nos três habitats, Rattus rattus foi capturada na floresta e na pastagem e Rattus norvegicus só foi capturada na lixeira. Na ilha do Corvo não conseguimos efectuar nenhuma captura de animais destas espécies. Apresentamos os dados da fertilidade potencial das fêmeas prenhas capturados e dados sobres as medidas de algumas características da morfologia externa. Sugerimos um padrão de distribuição das três espécies para o Arquipélago dos Açores e apresentamos uma forma simples e expedita para a identificação das espécies de Rodentia nos Açores

Uniformity transition for ray intensities in random media

This paper analyses a model for the intensity of distribution for rays propagating without absorption in a random medium. The random medium is modelled as a dynamical map. After N iterations, the intensity is modelled as a sum S of N contributions from different trajectories, each of which is a product of N independent identically distributed random variables xk, representing successive focussing or de-focussing events. The number of ray trajectories reaching a given point is assumed to proliferate exponentially: N=ΛN, for some Λ>1. We investigate the probability distribution of S. We find a phase transition as parameters of the model are varied. There is a phase where the fluctuations of S are suppressed as N → ∞, and a phase where the S has large fluctuations, for which we provide a large deviation analysis

Influence of Disorder Strength on Phase Field Models of Interfacial Growth

We study the influence of disorder strength on the interface roughening process in a phase-field model with locally conserved dynamics. We consider two cases where the mobility coefficient multiplying the locally conserved current is either constant throughout the system (the two-sided model) or becomes zero in the phase into which the interface advances (one-sided model). In the limit of weak disorder, both models are completely equivalent and can reproduce the physical process of a fluid diffusively invading a porous media, where super-rough scaling of the interface fluctuations occurs. On the other hand, increasing disorder causes the scaling properties to change to intrinsic anomalous scaling. In the limit of strong disorder this behavior prevails for the one-sided model, whereas for the two-sided case, nucleation of domains in front of the invading front are observed.Comment: Accepted for publication in PR

Benefits of regular table tennis practice in body composition and physical fitness compared to physically active children aged 10–11 years

The aim of this study was to identify the differences in body composition and physical fitness between children who played table tennis regularly during a two-year period compared to physically active children who were not engaged in a regular activity. Three hundred seventy-four children aged 10 to 11 years were divided into two groups: table tennis players (n = 109 boys and 73 girls) and physically active group (n = 88 boys and 104 girls). Anthropometric analysis included body mass index, skinfolds, perimeters and bone diameters. Somatotype and body composition were determined according to age-specific equations. Physical fitness assessment included hand grip dynamometry (strength), sit-and-reach test (range of movement) and maximal multistage 20 m shuttle run test (cardiovascular fitness). The result show that children who regularly played table tennis had greater bone development and superior physical fitness compared to those who were physically active but not engaged in a regular physical activity. This is the largest study to date presenting data about the potential of table tennis to benefit health in children. These results constitute an important first step in clarifying the effectiveness of table tennis as a health-promotion strategy to encourage children to undertake regular physical activity and limit sedentary behavior