15,751 research outputs found
Immunodeficiency-associated viral oncogenesis
AbstractSeveral viruses with different replication mechanisms contribute to oncogenesis by both direct and indirect mechanisms in immunosuppressed subjects after solid organ transplantation, after allogeneic stem cell transplantation, or with human immunodeficiency virus (HIV) infection. Epstein–Barr virus (EBV), human papillomavirus (HPV), Kaposi sarcoma herpesvirus (KSHV), human T-cell lymphotropic virus type 1 (HTLV-1) and Merkel cell polyoma virus (MCV) are the main viruses associated with the development of cancer in immunosuppressed patients. Besides being a main cause of immunodeficiency, HIV1 has a direct pro-oncogenic effect. In this review, we provide an update on the association between the condition of acquired immunodeficiency and cancer risk, specifically addressing the contributions to oncogenesis of HPV, MCV, KSHV, HTLV-1, and EBV
Extinction properties of the X-ray bright/optically faint afterglow of GRB 020405
We present an optical-to-X-ray spectral analysis of the afterglow of GRB
020405. The optical spectral energy distribution not corrected for the
extragalactic extinction is significantly below the X-ray extrapolation of the
single powerlaw spectral model suggested by multiwavelength studies. We
investigate whether considerable extinction could explain the observed spectral
``mismatch'' by testing several types of extinction curves. For the first time
we test extinction curves computed with time-dependent numerical simulations of
dust grains destruction by the burst radiation. We find that an extinction law
weakly depen dent on wavelength can reconcile the unabsorbed optical and X-ray
data with the expected synchrotron spectrum. A gray extinction law can be
provided by a dust grain size distribution biased toward large grains.Comment: 6 pages, 5 figures, accepted for publication on A&
Automotive Stirling Engine Development Program
Mod I engine testing and test results, the test of a Mod I engine in the United States, Mod I engine characterization and analysis, Mod I Transient Test Bed fuel economy, Mod I-A engine performance are discussed. Stirling engine reference engine manufacturing and reduced size studies, components and subsystems, and the study and test of low-cost casting alloys are also covered. The overall program philosophy is outlined, and data and results are presented
Anemia in Cardio-Renal Syndrome: clinical impact and pathophysiologic mechanisms
Anemia is a disease that is often associated with heart failure (HF) and renal
insufficiency (RI). This unfavorable triad of conditions has been called
Cardio-Renal-Anemia Syndrome (CRS). The association of HF, RI, and anemia is
poorly reported in multicenter clinical trials, so the pathophysiologic
mechanisms and treatment options need to be better defined. When CRS patients
develop anemia, a "perfect storm" often occurs: HF and RI cause anemia which will
worsen the first two conditions. Anemia appears to be the result of complex
interactions between cardiac performance, bone marrow homeostasis, renal
dysfunction, and various drug side effects. However, neurohormonal and
inflammatory activities play a key role in the beginning and progression of the
disease. As a consequence, endogenous erythropoietin activity dysfunction with
inadequate production and tissue resistance occurs. Despite the advances of
therapy in the neurohormonal activation blockade, mortality and hospitalization
in HF still remain unacceptably high, suggesting that specific comorbidity
treatments could have a significant positive prognostic impact. Anemia should be
recognized as one of the novel targets in HF treatmen
Automotive Stirling engine development program
Activities performed on Mod I engine testing and test results, testing of the Mod I engine in the United States, Mod I engine characterization and analyses, Mod I Transient Test Bed fuel economy, upgraded Mod I performance and testing, Stirling engine reference engine manufacturing and reduced size studied, components and subsystems, and the study and test of low cost casting alloys are summarized. The overall program philosophy is outlined, and data and results are presented
Automotive Stirling Engine Development Program
Program status and plans are discussed for component and technology development; reference engine system design, the upgraded Mod 1 engine; industry test and evaluation; and product assurance. Four current Mod 1 engines reached a total of 2523 operational hours, while two upgraded engines accumulated 166 hours
Advances on GRB as cosmological tools
Several interesting correlations among Gamma Ray Bursts (GRB) prompt and
afterglow properties have been found in the recent years. Some of these
correlations have been proposed also to standardize GRB energetics to use them
as standard candles in constraining the expansion history of the universe up to
z>6. However, given the still unexplained nature of most of these correlations,
only the less scattered correlations can be used for constraining the
cosmological parameters. The updated E_peak-E_gamma correlation is presented.
Caveats of alternative methods of standardizing GRB energetics are discussed.Comment: 8 parges, AIP conf. proc. "Probing stellar populations out to the
distant universe, Cefalu' 2008" Vol. 1111, pp. 579-58
Multi-wavelength analysis of the field of the dark burst GRB 031220
We have collected and analyzed data taken in different spectral bands (from
X-ray to optical and infrared) of the field of GRB031220 and we present results
of such multiband observations. Comparison between images taken at different
epochs in the same filters did not reveal any strong variable source in the
field of this burst. X-ray analysis shows that only two of the seven Chandra
sources have a significant flux decrease and seem to be the most likely
afterglow candidates. Both sources do not show the typical values of the R-K
colour but they appear to be redder. However, only one source has an X-ray
decay index (1.3 +/- 0.1) that is typical for observed afterglows. We assume
that this source is the best afterglow candidate and we estimate a redshift of
1.90 +/- 0.30. Photometric analysis and redshift estimation for this object
suggest that this GRB can be classified as a Dark Burst and that the
obscuration is the result of dust extinction in the circum burst medium or
inside the host galaxy.Comment: 7 pages, 5 figures, accepted for publication on A&
Phylogenetic systematics of Baccharis (Asteraceae: Astereae), a mega-diverse plant genus in the Americas.
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