3,852 research outputs found

    X-ray Orbital Modulations in Intermediate Polars

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    We present an analysis of 30 archival ASCA and RXTE X-ray observations of 16 intermediate polars to investigate the nature of their orbital modulation. We show that X-ray orbital modulation is widespread amongst these systems, but not ubiquitous as indicated by previous studies that included fewer objects. Only seven of the sixteen systems show a clearly statistically significant modulation depth whose amplitude decreases with increasing X-ray energy. Interpreting this as due to photoelectric absorption in material at the edge of an accretion disc would imply that such modulations are visible for all system inclination angles in excess of 60 degrees. However, it is also apparent that the presence of an X-ray orbital modulation can appear and disappear on a timescale of ~years or months in an individual system. This may be evidence for the presence of a precessing, tilted accretion disc, as inferred in some low mass X-ray binaries.Comment: Accepted for publication in Astronomy & Astrophysics. 9 pages of text, plus 5 pages of tables, plus 33 pages of figure

    Politics in Southern Africa: State and Society in Transition

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    Mammals of the Upper Henty River Region, Western Tasmania

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    A mammal survey was conducted in the Upper Henty River Region in western Tasmania. The area had been subject to much disturbance from mining, forestry and frequent fires and was covered by a maze of roads and tracks. Nineteen native species (including bats) were recorded. Four of the species listed in 1983 as occurring in the Lower Gordon Region, 80 km south of the present study area, were not recorded during our survey. It is considered that three of these species would probably have been found in the area with further searching. The fourth species, Mastacomysfuscus, is thought not to be present due to increased fire frequency in the sedgeland areas compared with the Lower Gordon Region. Potorous tridactylus is recorded for the first time from rainforest. Microhabitat selection by Rattus lutreolus and Pseudomys higginsi differed from that previously reported. Disturbance from road construction led to the creation of a new food source for Thylogale billardierii. The abundance of tracks in the area increased ease of movement for carnivorous mammals. Only one introduced species Felis catus, which is also known to occur in the Lower Gordon, was recorded. Disturbance had thus not led to an invasion of exotics

    Lived experiences of young pregnant women who smoke

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    Background Smoking tobacco during pregnancy can lead to adverse pregnancy and child health outcomes. Aim To gain insight of smoking during pregnancy from young pregnant women’s lived experience. Method A descriptive phenomenological approach was used. Semi-structured interviews were conducted with five women aged 18-20 years who had smoked tobacco during pregnancy. Findings Themes that emerged from the data were related to culture and routine, psychological wellbeing, self-efficacy, public opinion, recognition of harm, whom they spoke to about smoking, and the approaches that helped behaviour change. Conclusions Midwives were seen as the trusted health professional by the young women and a non-judgemental approach was valued to promote self-efficacy. Smoking cessation services were not recognised as beneficial, and cutting down, rather than using nicotine replacement therapy or e-cigarettes, was preferred

    Analytic moduli spaces of simple sheaves on families of integral curves

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    We prove the existence of fine moduli spaces of simple coherent sheaves on families of irreducible curves. Our proof is based on the existence of a universal upper bound of the Castelnuovo-Mumford regularity of such sheaves, which we provide.Comment: typos corrected, final version, to appear in Mathematischen Nachrichte

    The therapeutic efficacy and macrofilaricidal activity of doxycycline for the treatment of river blindness

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    Background. Onchocerca volvulus and lymphatic filariae, causing river blindness and elephantiasis, depend on endosymbiotic Wolbachia bacteria for growth, development, fertility, and survival. Clinical trials have shown that doxycycline treatment eliminates Wolbachia, causing long-term sterilization of adult female filariae and effecting potent macrofilaricidal activity. The continual reinfection by drug-naive worms that occurs in these trial settings dilutes observable anti-Wolbachia and antifilarial effects, making it difficult to estimate therapeutic efficacy and compare different doxycycline regimens, evaluated at different times after treatment. Methods. A meta-analytical modeling framework is developed to link all usable data collected from clinical trials measuring the Wolbachia status and viability of individual female adult worms collected at various times after treatment with 4, 5, or 6 weeks of daily 100 or 200 mg oral doxycycline. The framework is used to estimate efficacy parameters that are not directly measurable as trial outcomes. Results. The estimated efficacy of doxycycline (the maximum proportional reduction in the percentage of adult female O. volvulus positive for Wolbachia) is 91%–94% on average, irrespective of the treatment regimen. Efficacy is >95% in the majority of trial participants. The life span of Wolbachia-depleted worms is reduced by 70%–80%, from approximately 10 years to 2–3 years. Conclusions. The efficacy parameters are pertinent to the prospects of using doxycycline on a “test and treat” basis for onchocerciasis control and confirm doxycycline as a potent macrofilaricidal therapy. The modeling approach is more generally relevant to the design and evaluation of clinical trials for antifilarial drugs conducted in endemic settings
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