137 research outputs found

    A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279

    Get PDF
    It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and gamma-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10^5 gravitational radii.Comment: Published in Nature issued on 18 February 2010. Corresponding authors: Masaaki Hayashida and Greg Madejsk

    Stress-related cardiomyopathies

    Get PDF
    Stress-related cardiomyopathies can be observed in the four following situations: Takotsubo cardiomyopathy or apical ballooning syndrome; acute left ventricular dysfunction associated with subarachnoid hemorrhage; acute left ventricular dysfunction associated with pheochromocytoma and exogenous catecholamine administration; acute left ventricular dysfunction in the critically ill. Cardiac toxicity was mediated more by catecholamines released directly into the heart via neural connection than by those reaching the heart via the bloodstream. The mechanisms underlying the association between this generalized autonomic storm secondary to a life-threatening stress and myocardial toxicity are widely discussed. Takotsubo cardiomyopathy has been reported all over the world and has been acknowledged by the American Heart Association as a form of reversible cardiomyopathy. Four "Mayo Clinic" diagnostic criteria are required for the diagnosis of Takotsubo cardiomyopathy: 1) transient left ventricular wall motion abnormalities involving the apical and/or midventricular myocardial segments with wall motion abnormalities extending beyond a single epicardial coronary artery distribution; 2) absence of obstructive epicardial coronary artery disease that could be responsible for the observed wall motion abnormality; 3) ECG abnormalities, such as transient ST-segment elevation and/or diffuse T wave inversion associated with a slight troponin elevation; and 4) the lack of proven pheochromocytoma and myocarditis. ECG changes and LV dysfunction occur frequently following subarachnoid hemorrhage and ischemic stroke. This entity, referred as neurocardiogenic stunning, was called neurogenic stress-related cardiomyopathy. Stress-related cardiomyopathy has been reported in patients with pheochromocytoma and in patients receiving intravenous exogenous catecholamine administration. The role of a huge increase in endogenous and/or exogenous catecholamine level in critically ill patients (severe sepsis, post cardiac resuscitation, post tachycardia) to explain the onset of myocardial dysfunction was discussed. Further research is needed to understand this complex interaction between heart and brain and to identify risk factors and therapeutic and preventive strategies

    An Analysis of the Role of the Indigenous Microbiota in Cholesterol Gallstone Pathogenesis

    Get PDF
    Background and Aims: Cholesterol gallstone disease is a complex process involving both genetic and environmental variables. No information exists regarding what role if any the indigenous gastrointestinal microbiota may play in cholesterol gallstone pathogenesis and whether variations in the microbiota can alter cholesterol gallstone prevalence rates. Methods: Genetically related substrains (BALB/cJ and BALB/cJBomTac) and (BALB/AnNTac and BALB/cByJ) of mice obtained from different vendors were compared for cholesterol gallstone prevalence after being fed a lithogenic diet for 8 weeks. The indigenous microbiome was altered in these substrains by oral gavage of fecal slurries as adults, by cross-fostering to mice with divergent flora at <1day of age or by rederiving into a germ-free state. Results: Alterations in the indigenous microbiome altered significantly the accumulation of mucin gel and normalized gallbladder weight but did not alter cholesterol gallstone susceptibility in conventionally housed SPF mice. Germ-free rederivation rendered mice more susceptible to cholesterol gallstone formation. This susceptibility appeared to be largely due to alterations in gallbladder size and gallbladder wall inflammation. Colonization of germ-free mice with members of altered Schaedler flora normalized the gallstone phenotype to a level similar to conventionally housed mice. Conclusions: These data demonstrate that alterations in the gastrointestinal microbiome may alter aspects of cholesterol gallstone pathogenesis and that in the appropriate circumstances these changes may impact cholesterol cholelithogenesis.National Institutes of Health (U.S.) (Grant T32OD010978)National Institutes of Health (U.S.) (Grant P30ES002109)National Institutes of Health (U.S.) (Grant R01AT004326

    Standard of Practice for the Endovascular Treatment of Thoracic Aortic Aneurysms and Type B Dissections

    Get PDF
    Thoracic endovascular aortic repair (TEVAR) represents a minimally invasive technique alternative to conventional open surgical reconstruction for the treatment of thoracic aortic pathologies. Rapid advances in endovascular technology and procedural breakthroughs have contributed to a dramatic transformation of the entire field of thoracic aortic surgery. TEVAR procedures can be challenging and, at times, extraordinarily difficult. They require seasoned endovascular experience and refined skills. Of all endovascular procedures, meticulous assessment of anatomy and preoperative procedure planning are absolutely paramount to produce optimal outcomes. These guidelines are intended for use in quality-improvement programs that assess the standard of care expected from all physicians who perform TEVAR procedures

    The Hi-GAL compact source catalogue – I. The physical properties of the clumps in the inner Galaxy (−71. ◩ 0 < ℓ < 67.◩ 0)

    Get PDF
    Hi-GAL (Herschel InfraRed Galactic Plane Survey) is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 ”m. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogues presented in Molinari et al., covering the portion of Galactic plane −71.◩ 0 < ℓ < 67.◩ 0. The band-merged catalogue contains 100 922 sources with a regular SED, 24 584 of which show a 70-”m counterpart and are thus considered protostellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterize different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in protostellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to protostellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between 'on-arm' and 'interarm' positions

    HIV Antigen Incorporation within Adenovirus Hexon Hypervariable 2 for a Novel HIV Vaccine Approach

    Get PDF
    Adenoviral (Ad) vectors have been used for a variety of vaccine applications including cancer and infectious diseases. Traditionally, Ad-based vaccines are designed to express antigens through transgene expression of a given antigen. However, in some cases these conventional Ad-based vaccines have had sub-optimal clinical results. These sub-optimal results are attributed in part to pre-existing Ad serotype 5 (Ad5) immunity. In order to circumvent the need for antigen expression via transgene incorporation, the “antigen capsid-incorporation” strategy has been developed and used for Ad-based vaccine development in the context of a few diseases. This strategy embodies the incorporation of antigenic peptides within the capsid structure of viral vectors. The major capsid protein hexon has been utilized for these capsid incorporation strategies due to hexon's natural role in the generation of anti-Ad immune response and its numerical representation within the Ad virion. Using this strategy, we have developed the means to incorporate heterologous peptide epitopes specifically within the major surface-exposed domains of the Ad capsid protein hexon. Our study herein focuses on generation of multivalent vaccine vectors presenting HIV antigens within the Ad capsid protein hexon, as well as expressing an HIV antigen as a transgene. These novel vectors utilize HVR2 as an incorporation site for a twenty-four amino acid region of the HIV membrane proximal ectodomain region (MPER), derived from HIV glycoprotein gp41 (gp41). Our study herein illustrates that our multivalent anti-HIV vectors elicit a cellular anti-HIV response. Furthermore, vaccinations with these vectors, which present HIV antigens at HVR2, elicit a HIV epitope-specific humoral immune response

    A first glimpse at the Galactic plane with the ASKAP: the SCORPIO field

    Get PDF
    In the broad context of the Australian Square Kilometer Array Pathfinder (ASKAP) early-science phase and preparation for the related surveys, we report the first radio observations towards the Galactic plane. The targeted field was chosen to encompass the entire SCORPIO survey, one of the several pathfinder projects for the Evolutionary Map of the Universe survey planned with the ASKAP. The observations were carried out in 2018 January at a central frequency of 912 MHz, with 15 operational antennas, and covered a total area of about 40 square degrees in three different pointings. The final image has a resolution of 24.1 × 21.1 arcsec2 and a median rms of 541 ÎŒJy beam−1⁠. We were able to extract 3545 candidate sources, 75 per cent of them point sources. For a preliminary validation, a comparison with the 843 MHz Molonglo Galactic Plane Survey is presented. Although the present observations were obtained with the ASKAP only partially deployed, its unique capability to map complex sources, such as those inhabiting the Galactic plane, at different angular scales, is highlighted. Within the SCORPIO field all the previously classified H II regions, Planetary Nebulae (PNe), and supernovae remnants (SNRs), previously known to be radio sources, were detected. We also report new radio detections from several H II regions previously classified as ‘candidates’ or ‘radio quiet’ and from half of all the PNe in the SCORPIO field with robust classification. Most notably, we find numerous unclassified, extended sources which constitute a promising sample of candidates H II regions and SNRs

    Hi-GAL: The Herschel Infrared Galactic Plane Survey

    Get PDF
    Hi-GAL, the Herschel infrared Galactic Plane Survey, is an Open Time Key Project of the Herschel Space Observatory. It will make an unbiased photometric survey of the inner Galactic plane by mapping a 2° wide strip in the longitude range midlmid < 60° in five wavebands between 70 Όm and 500 Όm. The aim of Hi-GAL is to detect the earliest phases of the formation of molecular clouds and high-mass stars and to use the optimum combination of Herschel wavelength coverage, sensitivity, mapping strategy, and speed to deliver a homogeneous census of star-forming regions and cold structures in the interstellar medium. The resulting representative samples will yield the variation of source temperature, luminosity, mass and age in a wide range of Galactic environments at all scales from massive YSOs in protoclusters to entire spiral arms, providing an evolutionary sequence for the formation of intermediate and high-mass stars. This information is essential to the formulation of a predictive global model of the role of environment and feedback in regulating the star-formation process. Such a model is vital to understanding star formation on galactic scales and in the early universe. Hi-GAL will also provide a science legacy for decades to come with incalculable potential for systematic and serendipitous science in a wide range of astronomical fields, enabling the optimum use of future major facilities such as JWST and ALMA

    The Co-Ordinated radio and infrared survey for high-mass star formation – V. The CORNISH-South survey and catalogue

    Get PDF
    We present the first high spatial resolution radio continuum survey of the southern Galactic plane. The CORNISH project has mapped the region defined by 295○ < l < 350○; |b| < 1○ at 5.5-GHz, with a resolution of 2.5″ (FWHM). As with the CORNISH-North survey, this is designed to primarily provide matching radio data to the Spitzer GLIMPSE survey region. The CORNISH-South survey achieved a root mean square noise level of ∌ 0.11 mJy beam−1, using the 6A configuration of the Australia Telescope Compact Array (ATCA). In this paper, we discuss the observations, data processing and measurements of the source properties. Above a 7σ detection limit, 4701 sources were detected, and their ensemble properties show similar distributions with their northern counterparts. The catalogue is highly reliable and is complete to 90 per cent at a flux density level of 1.1 mJy. We developed a new way of measuring the integrated flux densities and angular sizes of non-Gaussian sources. The catalogue primarily provides positions, flux density measurements and angular sizes. All sources with IR counterparts at 8ÎŒm have been visually classified, utilizing additional imaging data from optical, near-IR, mid-IR, far-IR and sub-millimetre galactic plane surveys. This has resulted in the detection of 524 H II regions of which 255 are ultra-compact H II regions, 287 planetary nebulae, 79 radio stars and 6 massive young stellar objects. The rest of the sources are likely to be extra-galactic. These data are particularly important in the characterization and population studies of compact ionized sources such as UCHII regions and PNe towards the Galactic mid-plane
    • 

    corecore