3,279 research outputs found

    Electron Positron Annihilation Radiation from SgrA East at the Galactic Center

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    Maps of the Galactic electron-positron annihilation radiation show evidence for three distinct and significant features: (1) a central bulge source, (2) emission in the Galactic plane, and (3) an enhancement of emission at positive latitudes above the Galactic Center. In this paper, we explore the possibility that Sgr A East, a very prominent radio structure surrounding the Galactic nucleus, may be a significant contributer to the central bulge feature. The motivation for doing so stems from a recently proposed link between this radio object and the EGRET gamma-ray source 2EG J1746-2852. If this association is correct, then Sgr A East is also expected to be a source of copious positron production. The results presented here show that indeed Sgr A East must have produced a numerically significant population of positrons, but also that most of them have not yet had sufficient time to thermalize and annihilate. As such, Sgr A East by itself does not appear to be the dominant current source of annihilation radiation, but it will be when the positrons have cooled sufficiently and they have become thermalized. This raises the interesting possibility that the bulge component may be due to the relics of earlier explosive events like the one that produced Sgr A East.Comment: This manuscript was prepared with the AAS Latex macros v4.0 It is 37 pages long and has 16 figure

    Routine surveillance data on AIDS and HIV infections in the UK: a description of the data available and their use for short-term planning

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    In the UK surveillance of AIDS and HIV infection is based on routine reporting systems. Whilst attempts are made to ensure that AIDS data are as complete as possible, numbers of reports fluctuate from month to month for reasons which are described. In 1986 there was an increase in death certificates naming AIDS as a cause of death in patients who were not identifiable in the surveillance data. More active surveillance is now undertaken in order to minimize this and other possible discrepancies. It is probable that most cases of AIDS are reported and therefore these data can be used to describe trends in the epidemic by 'risk group'. Laboratory reports of HIV antibody-positive tests could give an earlier indication of trends because of the long incubation period of AIDS. But these laboratory data are difficult to interpret because they represent an incomplete and biased sample of all positive persons. AIDS cases are still being reported at a rate which is increasing approximately exponentially. Short-term predictions are presented showing a growth in the epidemic which is consistent with previously published predictions. Most cases are in the homosexual risk group. New asymptomatic homosexual patients with HIV antibody are still being identified. The epidemic of AIDS in haemophilia patients should be of finite size although new cases of AIDS are likely to continue to be diagnosed for several years. AIDS due to blood transfusion given in the UK before donor screening appears to be a much smaller epidemic. The epidemic in drug abusers is increasing. Heterosexually acquired AIDS and HIV infections are being reported in small but increasing numbers

    The effect of ranolazine on maintaining sinus rhythm in patients with resistant atrial fibrillation

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    Background: Atrial fibrillation (AF) may arise out of anomalous impulse activity at atrial venous junctions. Triggered activity may be a source of abnormal impulse activity. Ranolazine is an anti-anginal agent, which inhibits normal and abnormal late Na+ channel current in the ventricle and peak Na+ channel current in the atrium. This produces an energy sparing effect and stabilizes cardiac membranes. Ranolazine is a potent inhibitor of triggered activity. The purpose of this report is to describe our initial experience with ranolazine used in patients with resistant AF.Methods: Seven patients (4 males, 3 females, 67 ± 9 years) who developed recurrent AF within hours to a few days of restoring sinus rhythm despite AF ablation and /or failing one or more anti-arrhythmic agents were started on ranolazine (500-1000 mg/twice/day) after stopping all other anti-arrhythmic therapy. All but one patient had some form of associated structural heart disease. Results: Two patients received no apparent benefit from ranolazine developing recurrent AF within 2 days. All other patients derived significant benefit. Four patients have experienced no recurrent AF. The other patient relapsed at 3 months and again at 6 months. The mean time in sinus rhythm to date, or to the first relapse, for the five responders was 27 ± 11 weeks. No clinically evident pro-arrhythmic episodes occurred. Conclusion: Ranolazine was helpful in maintaining sinus rhythm in the majority of patients in which more established measures had failed. A controlled prospective trial is warranted to further investigate the efficacy of ranolazine in AF

    Prepartum Nutritional Strategies to Manage Postpartum Hypocalcemia

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    This information was presented at the 2015 Cornell Nutrition Conference for Feed Manufacturers, organized by the Department of Animal Science In the College of Agriculture and Life Sciences at Cornell University. Softcover copies of the entire conference proceedings may be purchased at http://ansci.cals.cornell.edu/extension-outreach/adult-extension/dairy-management/order-proceedings-resources

    The Evolution of X-ray Bursts in the "Bursting Pulsar" GRO J1744-28

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    GRO J1744-28, commonly known as the `Bursting Pulsar', is a low mass X-ray binary containing a neutron star and an evolved giant star. This system, together with the Rapid Burster (MXB 1730-33), are the only two systems that display the so-called Type II X-ray bursts. These type of bursts, which last for 10s of seconds, are thought to be caused by viscous instabilities in the disk; however the Type II bursts seen in GRO J1744-28 are qualitatively very different from those seen in the archetypal Type II bursting source the Rapid Burster. To understand these differences and to create a framework for future study, we perform a study of all X-ray observations of all 3 known outbursts of the Bursting Pulsar which contained Type II bursts, including a population study of all Type II X-ray bursts seen by RXTE. We find that the bursts from this source are best described in four distinct phenomena or `classes' and that the characteristics of the bursts evolve in a predictable way. We compare our results with what is known for the Rapid Burster and put out results in the context of models that try to explain this phenomena.Comment: Accepted to MNRAS Aug 17 201

    Relationships between the multiplication of chronic bee-paralysis virus and its associate particle

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    The amounts of chronic bee-paralysis virus associate (CPVA) produced in bees injected with purified chronic bee-paralysis virus (CPV) were negatively associated with the amounts, lengths of particles and maximum sedimentation coefficients of CPV. The ratio of the amounts of CPV/CPVA varied widely between individuals, but more CPVA was produced and CPV/CPVA ratios were smaller when CPVA was injected with the CPV preparations than when the latter were injected alone. The multiplication of the RNAs of CPV and of CPVA were also negatively correlated. The nature of the relationship between CPV and CPVA and the packaging arrangement of CPV RNA are discussed
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