6,494 research outputs found

    Warm HCN, C2H2, and CO in the disk of GV Tau

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    We present the first high-resolution, ground-based observations of HCN and C2H2 toward the T Tauri binary star system GV Tau. We detected strong absorption due to HCN nu_3 and weak C2H2 (nu_3 and nu_2 + (nu_4 + nu_5)^0_+) absorption toward the primary (GV Tau S) but not the infrared companion. We also report CO column densities and rotational temperatures, and present abundances relative to CO of HCN/CO ~0.6% and C2H2/CO ~1.2% and an upper limit for CH4/CO < 0.37% toward GV Tau S. Neither HCN nor C2H2 were detected toward the infrared companion and results suggest that abundances may differ between the two sources.Comment: 23 pages, 6 figures, accepted by Ap

    Survival of HIV-1 vertically infected children

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    PURPOSE OF REVIEW: It is 20 years since the start of the combination antiretroviral therapy (cART) era and more than 10 years since cART scale-up began in resource-limited settings. We examined survival of vertically HIV-infected infants and children in the cART era. RECENT FINDINGS: Good survival has been achieved on cART in all settings with up to 10-fold mortality reductions compared with before cART availability. Although mortality risk remains high in the first few months after cART initiation in young children with severe disease, it drops rapidly thereafter even for those who started with advanced disease, and longer term mortality risk is low. However, suboptimal retention on cART in routine programs threatens good survival outcomes and even on treatment children continue to experience high comorbidity risk; infections remain the major cause of death. Interventions to address infection risk include a cotrimoxazole prophylaxis, isoniazid preventive therapy, routine childhood and influenza immunization, and improving maternal survival. SUMMARY: Pediatric survival has improved substantially with cART and HIV-infected children are aging into adulthood. It is important to ensure access to diagnosis and early cART, good program retention as well as optimal comorbidity prophylaxis and treatment to achieve the best possible long-term survival and health outcomes for vertically infected children

    A Proper Motion Study of the Haro 6-10 Outflow: Evidence for a Subarcsecond Binary

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    We present single-dish and VLBI observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.3" north. Using the Very Long Baseline Array, we obtained five observations spanning 3 months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over 3 or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of ~45\deg. They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions (~220\deg) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH410, HH411, HH412, and HH184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of ~190\deg) must also originate in the vicinity of Haro6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H_2 emission in the spectrum of the northern component of the binary, Haro6-10N, none of outflows/jets can be tied directly to this young stellar object

    Law Libraries and Laboratories: The Legacies of Langdell and His Metaphor

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    Law Librarians and others have often referred to Harvard Law School Dean C.C. Langdell’s statements that the law library is the lawyer’s laboratory. Professor Danner examines the context of what Langdell through his other writings, the educational environment at Harvard in the late nineteenth century, and the changing perceptions of university libraries generally. He then considers how the “laboratory metaphor” has been applied by librarians and legal scholars during the twentieth century and into the twenty-first. The article closes with thoughts on Langdell’s legacy for law librarians and the usefulness of the laboratory metaphor

    Uniaxial magnetocrystalline anisotropy in CaRuO3{\rm CaRuO_3}

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    CaRuO3{\rm CaRuO_3} is a paramagnetic metal and since its low temperature resistivity is described by ρ=ρ0+ATγ\rho=\rho_0+AT^\gamma with γ1.5\gamma \sim 1.5, it is also considered a non-Fermi liquid (NFL) metal. We have performed extensive magnetoresistance and Hall effect measurements of untwinned epitaxial films of CaRuO3{\rm CaRuO_3}. These measurements reveal that CaRuO3{\rm CaRuO_3} exhibits uniaxial magnetocrystalline anisotropy. In addition, the low-temperature NFL behavior is most effectively suppressed when a magnetic field is applied along the easy axis, suggesting that critical spin fluctuations, possibly due to proximity of a quantum critical phase transition, are related to the NFL behavior.Comment: 7 figure

    Programming Protocol-Independent Packet Processors

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    P4 is a high-level language for programming protocol-independent packet processors. P4 works in conjunction with SDN control protocols like OpenFlow. In its current form, OpenFlow explicitly specifies protocol headers on which it operates. This set has grown from 12 to 41 fields in a few years, increasing the complexity of the specification while still not providing the flexibility to add new headers. In this paper we propose P4 as a strawman proposal for how OpenFlow should evolve in the future. We have three goals: (1) Reconfigurability in the field: Programmers should be able to change the way switches process packets once they are deployed. (2) Protocol independence: Switches should not be tied to any specific network protocols. (3) Target independence: Programmers should be able to describe packet-processing functionality independently of the specifics of the underlying hardware. As an example, we describe how to use P4 to configure a switch to add a new hierarchical label

    Geophysical characteristics and crustal structure of greenstone terranes: Canadian Shield

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    Geophysical studies in the Canadian Shield have provided some insights into the tectonic setting of greenstone belts. Greenstone belts are not rooted in deep crustal structures. Geophysical techniques consistently indicate that greenstones are restricted to the uppermost 10 km or so of crust and are underlain by geophysically normal crust. Gravity models suggest that granitic elements are similarly restricted, although magnetic modelling suggests possible downward extension to the intermediate discontinuity around approx. 18 km. Seismic evidence demonstrates that steeply-dipping structure, which can be associated with the belts in the upper crust, is not present in the lower crust. Horizontal intermediate discontinuities mapped under adjacent greenstone and granitic components are not noticeably disrupted in the boundary zone. Geophysical evidence points to the presence of discontinuities between greenhouse-granite and adjacent metasedimentary erranes. Measured stratigraphic thicknesses of greenstone belts are often twice or more the vertical thicknesses determined from gravity modelling. Explantations advanced for the discrepancy include stratigraphy repeated by thrust faulting and/or listric normal faulting, mechanisms which are consistent with certain aspects of conceptual models of greenstone development. Where repetition is not a factor the gravity evidence points to removal of the root zones of greenstone belts. For one region, this has been attributed to magmatic stopping during resurgent caldera activity

    Prevalence of liver fluke (Fasciola hepatica) in wild Red Deer (Cervus elaphus): coproantigen ELISA is a practicable alternative to faecal egg counting for surveillance in remote populations

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    Red deer (Cervus elaphus) are hosts of liver fluke (Fasciola hepatica); yet, prevalence is rarely quantified in wild populations. Testing fresh samples from remote regions by faecal examination (FE) can be logistically challenging; hence, we appraise frozen storage and the use of a coproantigen ELISA (cELISA) for F. hepatica surveillance. We also present cELISA surveillance data for red deer from the Highlands of Scotland. Diagnoses in faecal samples (207 frozen, 146 fresh) were compared using a cELISA and by FE. For each storage method (frozen or fresh), agreement between the two diagnostics was estimated at individual and population levels, where population prevalence was stratified into cohorts (e.g., by sampling location). To approximate sensitivity and specificity, 65 post-slaughter whole liver examinations were used as a reference. At the individual level, FE and cELISA diagnoses agreed moderately (κfrozen = 0.46; κfresh = 0.51), a likely reflection of their underlying principles. At the population level, FE and cELISA cohort prevalence correlated strongly (Pearson’s R = 0.89, p &lt; 0.0001), reflecting good agreement on relative differences between cohort prevalence. In frozen samples, prevalence by cELISA exceeded FE overall (42.8% vs. 25.8%) and in 9/12 cohorts, alluding to differences in sensitivity; though, in fresh samples, no significant difference was found. In 959 deer tested by cELISA across the Scottish Highlands, infection prevalence ranged from 9.6% to 53% by sampling location. We highlight two key advantages of cELISA over FE: i) the ability to store samples long term (frozen) without apparent loss in diagnostic power; and ii) reduced labour and the ability to process large batches. Further evaluation of cELISA sensitivity in red deer, where a range of fluke burdens can be obtained, is desirable. In the interim, the cELISA is a practicable diagnostic for F. hepatica surveillance in red deer, and its application here has revealed considerable geographic, temporal, sex and age related differences in F. hepatica prevalence in wild Scottish Highland red deer
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