1,474 research outputs found

    Poor Outcome in a Mitochondrial Neurogastrointestinal Encephalomyopathy Patient with a Novel TYMP Mutation: The Need for Early Diagnosis.

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    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a devastating autosomal recessive disorder due to mutations in TYMP, which cause loss of function of thymidine phosphorylase (TP), nucleoside accumulation in plasma and tissues and mitochondrial dysfunction. The clinical picture includes progressive gastrointestinal dysmotility, cachexia, ptosis and ophthalmoparesis, peripheral neuropathy and diffuse leukoencephalopathy, which usually lead to death in early adulthood. Therapeutic options are currently available in clinical practice (allogeneic hematopoietic stem cell transplantation and carrier erythrocyte entrapped TP therapy) and newer, promising therapies are expected in the near future. However, successful treatment is strictly related to early diagnosis. We report on an incomplete MNGIE phenotype in a young man harboring the novel heterozygote c.199 C>T (Q67X) mutation in exon 2, and the previously reported c.866 A>C (E289A) mutation in exon 7 in TYMP. The correct diagnosis was achieved many years after the onset of symptoms and unfortunately, the patient died soon after diagnosis because of multiorgan failure due to severe malnutrition and cachexia before any therapeutic option could be tried. To date, early diagnosis is essential to ensure that patients have the opportunity to be treated. MNGIE should be suspected in all patients who present with both gastrointestinal and nervous system involvement, even if the classical complete phenotype is lacking

    Unresolved Unidentified Source Contribution to the Gamma-ray Background

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    The large majority of EGRET point sources remain without an identified low-energy counterpart, and a large fraction of these sources are most likely extragalactic. Whatever the nature of the extragalactic EGRET unidentified sources, faint unresolved objects of the same class must have a contribution to the diffuse extragalactic gamma-ray background (EGRB). Understanding this component of the EGRB, along with other guaranteed contributions from known sources, is essential if we are to use this emission to constrain exotic high-energy physics. Here, we follow an empirical approach to estimate whether a potential contribution of unidentified sources to the EGRB is likely to be important, and we find that it is. Additionally, we show how upcoming GLAST observations of EGRET unidentified sources, as well as of their fainter counterparts, can be combined with GLAST observations of the Galactic and extragalactic diffuse backgrounds to shed light on the nature of the EGRET unidentified sources even without any positional association of such sources with low-energy counterparts.Comment: 11 pages, 5 figures, submitted to Ap

    The Pearson-Readhead Survey of Compact Extragalactic Radio Sources From Space. II. Analysis of Source Properties

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    We have performed a multi-dimensional correlation analysis on the observed properties of a statistically complete core-selected sample of compact radio-loud active galactic nuclei, based on data from the VLBI Space Observing Programme (Paper I) and previously published studies. Our sample is drawn from the well-studied Pearson-Readhead (PR) survey, and is ideally suited for investigating the general effects of relativistic beaming in compact radio sources. In addition to confirming many previously known correlations, we have discovered several new trends that lend additional support to the beaming model. These trends suggest that the most highly beamed sources in core-selected samples tend to have a) high optical polarizations; b) large pc/kpc-scale jet misalignments; c) prominent VLBI core components; d) one-sided, core, or halo radio morphology on kiloparsec scales; e) narrow emission line equivalent widths; and f) a strong tendency for intraday variability at radio wavelengths. We have used higher resolution space and ground-based VLBI maps to confirm the bi-modality of the jet misalignment distribution for the PR survey, and find that the sources with aligned parsec- and kiloparsec-scale jets generally have arcsecond-scale radio emission on both sides of the core. The aligned sources also have broader emission line widths. We find evidence that the BL Lacertae objects in the PR survey are all highly beamed, and have very similar properties to the high-optically polarized quasars, with the exception of smaller redshifts. A cluster analysis on our data shows that after partialing out the effects of redshift, the luminosities of our sample objects in various wave bands are generally well-correlated with each other, but not with other source properties.Comment: 21 pages, 10 figures. Accepted for publication in the Astrophysical Journal. Part I can be found at astro-ph/010227

    Mudanças no regime hidrológico da bacia hidrográfica do Rio Taquari-Pantanal.

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    A inundação de 11.000 km2 no Pantanal, iniciada na década de 70, vem causando prejuízos à pecuária bovina e alterações na flora nativa. Esta inundação atribuída ao assoreamento do rio Taquari pode também estar associada a mudança no regime hidrológico, passando de um período seco para um período de chuvas e cheias maiores. As cheias maiores podem estar relacionadas ao aumento do desmatamento na bacia do alto Taquari (BAT). Foram analisadas vazões no rio Taquari, contribuições do nível do rio Paraguai e da precipitação na inundação. Também foi avaliado efeito da expansão da agropecuária na BAT sobre o aumento da vazão do rio Taquari, em Coxim. Contatou-se mudança significativa no regime hidrológico da planície do baixo curso do Taquari. A partir de 1973-74 inicio-se um período mais chuvoso e com cheias maiores. A defasagem de 3 a 4 meses entre a cheia do rio Paraguai com as chuvas na planície e a cheia do Taquari, possivelmente contribuem para manutenção da inundação na região por muitos meses. O aumento do aporte d'água da BAT para o Pantanal, observado a partir de meados da década de 70, foi influenciado, pelo aumento das chuvas e também pelo incremento do desmatamento na BAT.bitstream/item/37426/1/BP26.pd

    Testing the Blazar Paradigm: ASCA Observations of FSRQs with Steep Soft X-ray Spectra

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    We present the first observations at medium-hard X-rays with ASCA in 1998 August--November of four Flat Spectrum Radio Quasars (FSRQs), characterized by unusually steep soft X-ray spectra (photon index, \Gamma_{0.2-2.4 keV} \sim 2-2.5), as previously measured with ROSAT. Such steep X-ray slopes are similar to those observed in synchrotron-dominated BL Lacs and are unexpected in the context of the recent blazar paradigm, where sources with strong emission lines (such as FSRQs) are dominated in soft X-rays by a flat inverse Compton tail. We find that the ASCA spectra of the four FSRQs are consistent with a power law model with \Gamma_{2-10 keV} \sim 1.8, flatter than their ROSAT spectra. This indicates the onset of an inverse Compton component at energies \gtrsim 2 keV, in agreement with the blazar unification scheme. However, these objects are still anomalous within the blazar class for their steep soft X-ray continua which, together with non-simultaneous data at longer wavelengths, hint at the possibility that the synchrotron emission extends to soft X-rays. This would imply an anomalously high synchotron peak frequency for a quasar with luminous broad lines, challenging current blazar unification schemes. Alternatively, a plausible explanation for the steep optical-to-soft X-ray continua of the four FSRQs is thermal emission from the accretion disk, similar to the blazars 3C~273 and 3C~345. In the Appendix, we present fits to the SIS data in an effort to contribute to the ongoing calibration of the the time-dependence of the SIS response at low energies.Comment: accepted for publication in The Astrophysical Journa

    PSM in Italy: Troubled RAI in a Troubled Country

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    The chapter explores public service media in Italy. In the comparative literature the Italian RAI is often taken as a paradigmatic case of a highly (party) politicized public service broadcaster. Political interference has arguably been a constant feature of RAI’s sixty-year-long history, although the forms in which this phenomenon has manifested itself have changed considerably over time. After briefly contextualising historically and comparatively the case of public service media in Italy, the chapter sets out to discuss recent developments, including the effects of recent reforms to RAI’s governance and funding regimes. It then places these developments and the current debate over the role and future of RAI against the backdrop of a changing political landscape, the country’s ongoing economic problems and major social and cultural transformations
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