146 research outputs found

    O mediador social e pessoal nos cursos de educação e formação de adultos

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    Trabalho de projecto de mestrado, Ciências da Educação (Formação de Adultos), Universidade de Lisboa, Instituto de Educação, 2011Este trabalho de projecto, desenvolvido no âmbito das Ciências de Educação/ Formação de adultos, na área de especialização Formação de Adultos, teve como principal objectivo a análise do processo de formação dos mediadores de cursos de Educação e Formação de Adultos de Nível Secundário. Partindo da premissa de que os mediadores se formam através da experiência procurou-se com este trabalho identificar este processo e quais as suas práticas. A informação empírica resultou de entrevistas sobre a prática profissional dos entrevistados que trabalham num centro de formação profissional, na área da mediação social e pessoal. Verificou-se que o processo de formação dos mediadores é essencialmente não formal e informal sendo as experiências que vivem determinantes para a construção dos seus saberes, práticas e instrumentos de trabalho. A informação recolhida deu origem à criação de um projecto de intervenção no meio estudado com o objectivo de fornecer instrumentos aos novos mediadores e orientá-los nas suas novas funções, mantendo e potenciando o carácter experiencial deste processo formativo.This project work developed within the Science of Education/ Adults Education, specialized in adults vocational training, had as main objective the analysis of the learning process of mediators of the second grade vocational training courses for adults. Based on the thought that mediators learn their profession through experience, we sought to identify, with this work, this process and their practices. The empirical information resulted from interviews on the professional practices of the interviewed, who work in a vocational training centre, in the area of social and personal mediation. Was identified that the mediators’ learning process is essentially non-formal and informal being the experiences they lived, in professional context, extremely important to the building of their knowledge, practices and working tools. The obtained information originated an intervention project, in the studied vocational training centre, that aims to provide work tools for new mediators and to guide them in their new roles, maintaining and developing the experiential character of this learning process

    PSR J1907+0602: A Radio-Faint Gamma-Ray Pulsar Powering a Bright TeV Pulsar Wind Nebula

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    We present multiwavelength studies of the 106.6 ms gamma-ray pulsar PSR J1907+06 near the TeV source MGRO J1908+06. Timing observations with Fermi result in a precise position determination for the pulsar of R.A. = 19h07m547(2), decl. = +06:02:16(2) placing the pulsar firmly within the TeV source extent, suggesting the TeV source is the pulsar wind nebula of PSR J1907+0602. Pulsed gamma-ray emission is clearly visible at energies from 100 MeV to above 10 GeV. The phase-averaged power-law index in the energy range E > 0.1 GeV is = 1.76 \pm 0.05 with an exponential cutoff energy E_{c} = 3.6 \pm 0.5 GeV. We present the energy-dependent gamma-ray pulsed light curve as well as limits on off-pulse emission associated with the TeV source. We also report the detection of very faint (flux density of ~3.4 microJy) radio pulsations with the Arecibo telescope at 1.5 GHz having a dispersion measure DM = 82.1 \pm 1.1 cm^{-3}pc. This indicates a distance of 3.2 \pm 0.6 kpc and a pseudo-luminosity of L_{1400} ~ 0.035 mJy kpc^2. A Chandra ACIS observation revealed an absorbed, possibly extended, compact <(4 arcsec) X-ray source with significant non-thermal emission at R.A. = 19h07m54.76, decl. = +06:02:14.6 with a flux of 2.3^{+0.6}_{-1.4} X 10^{-14} erg cm^{-2} s^{-1}. From archival ASCA observations, we place upper limits on any arcminute scale 2--10 keV X-ray emission of ~ 1 X 10^{-13} erg cm^{-2} s^{-1}. The implied distance to the pulsar is compatible with that of the supernova remnant G40.5-0.5, located on the far side of the TeV nebula from PSR J1907+0602, and the S74 molecular cloud on the nearer side which we discuss as potential birth sites

    Fermi Large Area Telescope Observations of Gamma-ray Pulsars PSR J1057-5226, J1709-4429, and J1952+3252

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    The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057-5226, PSR J1709-4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from these pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.Comment: Accepted for publication in ApJ. 45 pages, 12 figures, 11 tables. Corresponding authors: O. Celik, F. Gargano, T. Reposeur, D.J. Thompso

    Fermi LAT Observation of Diffuse Gamma-Rays Produced Through Interactions between Local Interstellar Matter and High Energy Cosmic Rays

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    Observations by the Large Area Telescope (LAT) on the \textit{Fermi} mission of diffuse γ\gamma-rays in a mid-latitude region in the third quadrant (Galactic longitude ll from 200\arcdeg to 260\arcdeg and latitude b| b | from 22\arcdeg to 60\arcdeg) are reported. The region contains no known large molecular cloud and most of the atomic hydrogen is within 1 kpc of the solar system. The contributions of γ\gamma-ray point sources and inverse Compton scattering are estimated and subtracted. The residual γ\gamma-ray intensity exhibits a linear correlation with the atomic gas column density in energy from 100 MeV to 10 GeV. The measured integrated γ\gamma-ray emissivity is (1.63 \pm 0.05) \times 10^{-26} {\rm photons s^{-1} sr^{-1} H\mathchar`-atom^{-1}} and (0.66 \pm 0.02) \times 10^{-26} {\rm photons s^{-1} sr^{-1} H\mathchar`-atom^{-1}} above 100 MeV and above 300 MeV, respectively, with additional systematic error of 10\sim 10%. The differential emissivity in 100 MeV--10 GeV agrees with calculations based on cosmic ray spectra consistent with those directly measured, at the 10% level. The results obtained indicate that cosmic ray nuclei spectra within 1 kpc from the solar system in regions studied are close to the local interstellar spectra inferred from direct measurements at the Earth within 10\sim 10%.Comment: accepted for publication in the Astrophysical Journal. Revised according to the author proof.(correction of typos and minor revisions

    Discovery of Pulsed γ\gamma-rays from PSR J0034-0534 with the Fermi LAT: A Case for Co-located Radio and γ\gamma-ray Emission Regions

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    Millisecond pulsars (MSPs) have been firmly established as a class of gamma-ray emitters via the detection of pulsations above 0.1 GeV from eight MSPs by the Fermi Large Area Telescope (LAT). Using thirteen months of LAT data significant gamma-ray pulsations at the radio period have been detected from the MSP PSR J0034-0534, making it the ninth clear MSP detection by the LAT. The gamma-ray light curve shows two peaks separated by 0.274±\pm0.015 in phase which are very nearly aligned with the radio peaks, a phenomenon seen only in the Crab pulsar until now. The \geq0.1 GeV spectrum of this pulsar is well fit by an exponentially cutoff power law with a cutoff energy of 1.8±0.6±\pm 0.6\pm0.1 GeV and a photon index of 1.5±0.2±\pm 0.2\pm0.1, first errors are statistical and second are systematic. The near-alignment of the radio and gamma-ray peaks strongly suggests that the radio and gamma-ray emission regions are co-located and both are the result of caustic formation.Comment: 20 pages, 3 figures, 2 tables. Accepted for publication in Ap

    Fermi-LAT Search for Pulsar Wind Nebulae around gamma-ray Pulsars

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    The high sensitivity of the Fermi-LAT (Large Area Telescope) offers the first opportunity to study faint and extended GeV sources such as pulsar wind nebulae (PWNe). After one year of observation the LAT detected and identified three pulsar wind nebulae: the Crab Nebula, Vela-X and the PWN inside MSH 15-52. In the meantime, the list of LAT detected pulsars increased steadily. These pulsars are characterized by high energy loss rates from ~3 \times 10^{33} erg s1^{-1} to 5 \times 1038^{38} erg s1^{-1} and are therefore likely to power a PWN. This paper summarizes the search for PWNe in the off-pulse windows of 54 LAT-detected pulsars using 16 months of survey observations. Ten sources show significant emission, seven of these likely being of magnetospheric origin. The detection of significant emission in the off-pulse interval offers new constraints on the gamma-ray emitting regions in pulsar magnetospheres. The three other sources with significant emission are the Crab Nebula, Vela-X and a new pulsar wind nebula candidate associated with the LAT pulsar PSR J1023-5746, coincident with the TeV source HESS J1023-575. We further explore the association between the H.E.S.S. and the Fermi source by modeling its spectral energy distribution. Flux upper limits derived for the 44 remaining sources are used to provide new constraints on famous PWNe that have been detected at keV and/or TeV energies.Comment: Accepted for publication in Astrophysical Journal, 42 pages, 17 figure

    Detection of the energetic pulsar PSR B1509-58 and its pulsar wind nebula in MSH 15-52 using the Fermi-Large Area Telescope

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    We report the detection of high energy gamma-ray emission from the young and energetic pulsar PSR B1509-58 and its pulsar wind nebula (PWN) in the composite supernova remnant SNR G320.4-1.2 (aka MSH 15-52). Using 1 year of survey data with the Fermi-Large Area Telescope (LAT), we detected pulsations from PSR B1509-58 up to 1 GeV and extended gamma-ray emission above 1 GeV spatially coincident with the PWN. The pulsar light curve presents two peaks offset from the radio peak by phases 0.96 ±\pm 0.01 and 0.33 ±\pm 0.02. New constraining upper limits on the pulsar emission are derived below 1 GeV and confirm a severe spectral break at a few tens of MeV. The nebular spectrum in the 1 - 100 GeV energy range is well described by a power-law with a spectral index of (1.57 ±\pm 0.17 ±\pm 0.13) and a flux above 1 GeV of (2.91 ±\pm 0.79 ±\pm 1.35) 10^{-9} cm^{-2} s^{-1}. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. The LAT spectrum of the nebula connects nicely with Cherenkov observations, and indicates a spectral break between GeV and TeV energies.Comment: 14 pages, 6 figures, accepted for publication by Ap

    Bovine tuberculosis at a cattle-small ruminant-human interface in Meskan, Gurage region, Central Ethiopia

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    ABSTRACT: BACKGROUND: Bovine tuberculosis (BTB) is endemic in Ethiopian cattle. The aim of this study was to assess BTB prevalence at an intensive contact interface in Meskan Woreda (district) in cattle, small ruminants and suspected TB-lymphadenitis (TBLN) human patients. METHODS: The comparative intradermal test (CIDT) was carried out for all animals involved in the cross-sectional study and results interpreted using a < 4 mm and a < 2 mm cut-off. One PPD positive goat was slaughtered and lymph nodes subjected to culture and molecular typing. In the same villages, people with lymphadenitis were subjected to clinical examination. Fine needle aspirates (FNA) were taken from suspected TBLN and analyzed by smear microscopy and molecular typing. RESULTS: A total of 1214 cattle and 406 small ruminants were tested for BTB. In cattle, overall individual prevalence (< 2 mm cut-off) was 6.8% (CI: 5.4-8.5%) with 100% herd prevalence. Only three small ruminants (2 sheep and 1 goat) were reactors. The overall individual prevalence in small ruminants (< 2 mm cut-off) was 0.4% (CI: 0.03-5.1%) with 25% herd prevalence. Cattle from owners with PPD positive small ruminants were all PPD negative. 83% of the owners kept their sheep and goats inside their house at night and 5% drank regularly goat milk.FNAs were taken from 33 TBLN suspected cases out of a total of 127 screened individuals with lymph node swellings. Based on cytology results, 12 were confirmed TBLN cases. Nine out of 33 cultures were AFB positive. Culture positive samples were subjected to molecular typing and they all yielded M. tuberculosis. M. tuberculosis was also isolated from the goat that was slaughtered. CONCLUSIONS: This study highlighted a low BTB prevalence in sheep and goats despite intensive contact with cattle reactors. TBLN in humans was caused entirely by M. tuberculosis, the human pathogen. M. tuberculosis seems to circulate also in livestock but their role at the interface is unknow

    Pulsar-Black Hole Binaries in the Galactic Center

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    Binaries consisting of a pulsar and a black hole (BH) are a holy grail of astrophysics, both for their significance for stellar evolution and for their potential application as probes of strong gravity. In spite of extensive surveys of our Galaxy and its system of globular clusters, no pulsar-black hole (PSR-BH) binary has been found to date. Clues as to where such systems might exist are therefore highly desirable. We show that if the central parsec around Sgr A* harbors a cluster of ~25,000 stellar BHs (as predicted by mass segregation arguments) and if it is also rich in recycled pulsar binaries (by analogy with globular clusters), then 3-body exchange interactions should produce PSR-BHs in the Galactic center. Simple estimates of the formation rate and survival time of these binaries suggest that a few PSR-BHs should be present in the central parsec today. The proposed formation mechanism makes unique predictions for the PSR-BH properties: 1) the binary would reside within ~1 pc of Sgr A*; 2) the pulsar would be recycled, with a period of ~1 to a few tens of milliseconds, and a low magnetic field B<~10^10 G; 3) the binary would have high eccentricity, e~0.8, but with a large scatter; and 4) the binary would be relatively wide, with semi-major axis a_b~0.1 - >~3 AU. The potential discovery of a PSR-BH binary therefore provides a strong motivation for deep, high-frequency radio searches for recycled pulsars toward the Galactic center.Comment: 13 pages, 1 figur
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