5,661 research outputs found

    An Ultraviolet-Excess Optical Candidate for the Luminous Globular Cluster X-ray Source in NGC1851

    Get PDF
    The intense, bursting X-ray source in the globular cluster NGC 1851 was one of the first cluster sources discovered, but has remained optically unidentified for 25 years. We report here on results from Hubble Space Telescope WFPC2 multicolor images in NGC 1851. Our high spatial resolution images resolve ~200 objects in the 3'' radius Einstein X-ray error circle, 40 times as many as in previous ground-based work. A color-magnitude diagram of the cluster clearly reveals a markedly UV-excess object with B~21, (U-B) ~ -0.9 only 2'' from the X-ray position. The UV-excess candidate is 0.12'' distant from a second, unremarkable star that is 0.5 mag brighter in B; thus ground-based studies of this field are probably impractical. Three other UV-excess objects are also present among the ~16,000 objects in the surveyed region of the cluster, leaving a ~5% probability that a UV-excess object has fallen in the X-ray error circle by chance. No variability of the candidate is seen in these data, although a more complete study is required. If this object is in fact the counterpart of the X-ray source, previous inferences that some globular cluster X-ray sources are optically subluminous with respect to low-mass X-ray binaries in the field are now strengthened.Comment: 13 pages including 1 table and 3 figures in AASTeX 4.0; To appear in The Astrophysical Journal Letters, volume 472 (1996 December 1). Preprint with full-resolution figures available at http://www.astro.washington.edu/deutsch/pubs/pubs.htm

    “Aren’t we all a little bisexual?” The Recognition of Bisexuality in an Unlikely Place

    Get PDF
    The hypermasculine subculture of men's team sports has traditionally been characterized by the one-time rule of homosexuality: one same-sex sexual experience is normally equated with a homosexual orientation. Thus, men have been polarized into sexual identity categories, erasing bisexuality as a legitimate or viable category of sexual identification. Accordingly, in this research the authors examine the perspectives on bisexuality among team sport athletes. Interviewing 60 male soccer players from three strategically selected U.S. universities, the authors show that these athletes accept bisexuality as a legitimate and nonstigmatized sexual identity. The authors find that the athletes intellectualize an understanding of bisexuality in highly complex ways. The authors also highlight that though only a very small minority have engaged in same-sex sexual behaviors, at some level, most players recognize some degree of bisexuality in their own identities. The authors suggest that these results are a product of increased exposure to and contact with homosexual persons, leading to decreasing cultural homohysteria, finally resulting in increasingly open discussion and complex understanding of sexual behaviors and identities that were once erased or stigmatized in men's team sport culture

    High-resolution antenna near-field imaging and sub-THz measurements with a small atomic vapor-cell sensing element

    Full text link
    Atomic sensing and measurement of millimeter-wave (mmW) and THz electric fields using quantum-optical EIT spectroscopy of Rydberg states in atomic vapors has garnered significant interest in recent years towards the development of atomic electric-field standards and sensor technologies. Here we describe recent work employing small atomic vapor cell sensing elements for near-field imaging of the radiation pattern of a Ku_u-band horn antenna at 13.49 GHz. We image fields at a spatial resolution of λ/10\lambda/10 and measure over a 72 to 240 V/m field range using off-resonance AC-Stark shifts of a Rydberg resonance. The same atomic sensing element is used to measure sub-THz electric fields at 255 GHz, an increase in mmW-frequency by more than one order of magnitude. The sub-THz field is measured over a continuous ±\pm100 MHz frequency band using a near-resonant mmW atomic transition

    Common community acquired infections and subsequent risk of chronic lymphocytic leukaemia

    Get PDF
    Emerging evidence supports a role for immune-related factors in the causation of chronic lymphocytic leukemia (CLL). Using the population-based U.S. SEER-Medicare database, we identified 10,171 elderly CLL patients and 122,531 frequency-matched controls to evaluate several community acquired infections associated with subsequent CLL risk. Odds ratios (ORs) were adjusted for gender, age, race, calendar year, and number of physician claims. We found increased CLL risk following Medicare claims for sinusitis (OR=1.11; 95%CI=1.05–1.17), pharyngitis (OR=1.15; 1.08–1.22), bronchitis (OR=1.14; 1.08–1.19), pneumonia (OR=1.17; 1.11–1.24), influenza (OR=1.10; 1.01–1.19), cellulitis (OR=1.08; 1.02–1.14), and herpes zoster (OR=1.26; 1.15–1.37). Associations with pneumonia and cellulitis remained significant when the 5-year period before diagnosis/control was excluded. CLL risk increased with increasing severity/frequency of pneumonia (p=0.005), cellulitis (p<0.001), and herpes zoster (p<0.001). Our findings suggest that common infections may play a role in CLL etiology. Alternatively, the associations might reflect an underlying immune disturbance present several years prior to CLL diagnosis

    Semiclassical Gravity in the Far Field Limit of Stars, Black Holes, and Wormholes

    Get PDF
    Semiclassical gravity is investigated in a large class of asymptotically flat, static, spherically symmetric spacetimes including those containing static stars, black holes, and wormholes. Specifically the stress-energy tensors of massless free spin 0 and spin 1/2 fields are computed to leading order in the asymptotic regions of these spacetimes. This is done for spin 0 fields in Schwarzschild spacetime using a WKB approximation. It is done numerically for the spin 1/2 field in Schwarzschild, extreme Reissner-Nordstrom, and various wormhole spacetimes. And it is done by finding analytic solutions to the leading order mode equations in a large class of asymptotically flat static spherically symmetric spacetimes. Agreement is shown between these various computational methods. It is found that for all of the spacetimes considered, the energy density and pressure in the asymptotic region are proportional to 1/r^5 to leading order. Furthermore, for the spin 1/2 field and the conformally coupled scalar field, the stress-energy tensor depends only on the leading order geometry in the far field limit. This is also true for the minimally coupled scalar field for spacetimes containing either a static star or a black hole, but not for spacetimes containing a wormhole.Comment: 43 pages, 2 figures. Reference added, minor changes, PRD versio

    Particulate and water-soluble carbon measured in recent snow at Summit, Greenland

    Get PDF
    Water-soluble organic carbon (WSOC), waterinsoluble particulate organic carbon (WIOC), and particulate elemental carbon (EC) were measured simultaneously for the first time on the Greenland Ice Sheet in surface snow and in a 3-meter snow pit. Snow pit concentrations reveal that, on average, WSOC makes up the majority (89%) of carbonaceous species, followed by WIOC (10%) and EC (1%). The enhancement of OC relative to EC (ratio 99:1) in Greenland snow suggests that, along with atmospheric particulate matter, gaseous organics contribute to snow-phase OC. Comparison of summer surface snow concentrations in 2006 with past summer snow pit layers (2002 – 2005) found a significant depletion in WSOC (20 – 82%) and WIOC (46 – 65%) relative to EC for 3 of the 4 years. The apparent substantial loss of WSOC and WIOC in aged snow suggests that post-depositional processes, such as photochemical reactions, need to be considered in linking ice core records of organics to atmospheric concentrations. Citation: Hagler, G. S. W., M. H. Bergin, E. A. Smith, J. E. Dibb, C. Anderson, and E. J. Steig (2007), Particulate and water-soluble carbon measured in recent snow at Summit, Greenland, Geophys. Res. Lett., 34, L16505, doi:10.1029/2007GL030110
    • …
    corecore