567 research outputs found

    Sexual behaviour in a fishing community on Lake Victoria, Uganda

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    This study describes the sexual behaviour of men and women in a fishing village on the shores of Lake Victoria in southwest Uganda. The village is near a well known trading town-truckstop on the main trans-Africa highway with a high recorded prevalence of HIV infection. Data were obtained on the daily travel and sexual activities of 26 women and 54 men with particular attention paid to the rate of partner change and the proportion of sexual contacts with people outside the village. During a total of 587 person-weeks the men made 1086 trips, mostly returning home the same day. They had a total of 1226 sexual contacts, most of which occurred either in their own village (83%) or a neighbouring fishing village (11%); 17 per cent of sexual contacts were with new partners. Fifteen of the women described themselves as married; 42 per cent of their sexual contacts were with casual, paying partners. Of the eleven women who were single, between 80 and 100 per cent of contacts were with paying partners. Most of the women’s partners were resident in the village. These data show a very high rate of sexual mixing within the village but little contact with people from outside. This suggests that all sexually active men and women in the village are at high risk of STDs including HIV. There is currently no formal health care available in the village. Such communities should be targeted in future STD control programs

    Grazing‐angle characterization of photosynthetic oxygen evolution protein monolayers

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    Variable‐period x‐ray standing wave (XSW) spectroscopy has been shown to be a practical probe for studying metalloproteins. The photosynthetic oxygen evolving complex (OEC) is a transmembrane multipolypeptide complex that catalyzes the oxidation of water to dioxygen. The OEC contains Mn, Ca, and Cl and is potentially amenable to study by XSW. In this feasibility study, preliminary results on OEC samples deposited on Au mirrors are discussed. First XSW measurements from the SSRL grazing‐incidence setup are presented. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70867/2/RSINAK-67-9-3364-5.pd

    Fisheries Exclusion Zones: Value and its sensitivity to data uncertainty

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    This paper focuses on the findings of the project that pertain particularly to the determination of the value of fisheries exclusion zones and the sensitivity of value estimation to data uncertainty. It necessarily draws on both the lite rature review and the case studies and in terms of its content extracts, presents and su mmarises the pertinent material therein covered. By collating this material a more directed consid eration of the topic of value is facilitated and the findings of the study as a whole more clear ly highlighted, and through consideration of uncertainty, also qualified

    Influence of age on respiratory modulation of muscle sympathetic nerve activity, blood pressure and baroreflex function in humans

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    New Findings What is the central question of this study? Does ageing influence the respiratory‐related bursting of muscle sympathetic nerve activity (MSNA) and the association between the rhythmic fluctuations in MSNA and blood pressure (Traube–Hering waves) that occur with respiration? What is the main finding and its importance? Despite the age‐related elevation in MSNA, the cyclical inhibition of MSNA during respiration is similar between young and older individuals. Furthermore, central respiratory–sympathetic coupling plays a role in the generation of Traube–Hering waves in both young and older humans. Healthy ageing and alterations in respiratory–sympathetic coupling have been independently linked with heightened sympathetic neural vasoconstrictor activity. We investigated how age influences the respiratory‐related modulation of muscle sympathetic nerve activity (MSNA) and the association between the rhythmic fluctuations in MSNA and blood pressure that occur with respiration (Traube–Hering waves; THW). Ten young (22 ± 2 years; mean ± SD) and 10 older healthy men (58 ± 6 years) were studied while resting supine and breathing spontaneously. MSNA, blood pressure and respiration were recorded simultaneously. Resting values were ascertained and respiratory cycle‐triggered averaging of MSNA and blood pressure measurements performed. The MSNA burst incidence was higher in older individuals [22.7 ± 9.2 versus 42.2 ± 13.7 bursts (100 heart beats)−1, P < 0.05], and was reduced to a similar extent in the inspiratory to postinspiratory period in young and older subjects (by ∌25% compared with mid‐ to late expiration). A similar attenuation of MSNA burst frequency (in bursts per minute), amplitude and total activity (burst frequency × mean burst amplitude) was also observed in the inspiratory to postinspiratory period in both groups. A significant positive correlation between respiratory‐related MSNA and the magnitude of Traube–Hering waves was observed in all young (100%) and most older subjects (80%). These data suggest that the strength of the cyclical inhibition of MSNA during respiration is similar between young and older individuals; thus, alterations in respiratory–sympathetic coupling appear not to contribute to the age‐related elevation in MSNA. Furthermore, central respiratory–sympathetic coupling plays a role in the generation of Traube–Hering waves in both healthy young and older humans

    Relationship Between Column-Density and Surface Mixing Ratio: Statistical Analysis of O3 and NO2 Data from the July 2011 Maryland DISCOVER-AQ Mission

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    To investigate the ability of column (or partial column) information to represent surface air quality, results of linear regression analyses between surface mixing ratio data and column abundances for O3 and NO2 are presented for the July 2011 Maryland deployment of the DISCOVER-AQ mission. Data collected by the P-3B aircraft, ground-based Pandora spectrometers, Aura/OMI satellite instrument, and simulations for July 2011 from the CMAQ air quality model during this deployment provide a large and varied data set, allowing this problem to be approached from multiple perspectives. O3 columns typically exhibited a statistically significant and high degree of correlation with surface data (R(sup 2) > 0.64) in the P- 3B data set, a moderate degree of correlation (0.16 < R(sup 2) < 0.64) in the CMAQ data set, and a low degree of correlation (R(sup 2) < 0.16) in the Pandora and OMI data sets. NO2 columns typically exhibited a low to moderate degree of correlation with surface data in each data set. The results of linear regression analyses for O3 exhibited smaller errors relative to the observations than NO2 regressions. These results suggest that O3 partial column observations from future satellite instruments with sufficient sensitivity to the lower troposphere can be meaningful for surface air quality analysis

    Application of OMI Observations to a Space-Based Indicator of NOx and VOC Controls on Surface Ozone Formation

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    We investigated variations in the relative sensitivity of surface ozone formation in summer to precursor species concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NOx) as inferred from the ratio of the tropospheric columns of formaldehyde to nitrogen dioxide (the "Ratio") from the Aura Ozone Monitoring Instrument (OMI). Our modeling study suggests that ozone formation decreases with reductions in VOCs at Ratios less than 1 and NOx at Ratios greater than 2; both NOx and VOC reductions may decrease ozone formation for Ratios between 1 and 2. Using this criteria. the OMI data indicate that ozone formation became: 1. more sensitive to NOx over most of the United States from 2005 to 2007 because of the substantial decrease in NOx emissions, primarily from stationary sources, and the concomitant decrease in the tropospheric column of NO2. and 2. more sensitive to NOx with increasing temperature, in part because emissions of highly reactive, biogenic isoprene increase with temperature, thus increasing the total VOC reactivity. In cities with relatively low isoprene emissions (e.g .. Chicago). the data clearly indicate that ozone formation became more sensitive to NOx from 2005 to 2007. In cities with relatively high isoprene emissions (e.g ., Atlanta), we found that the increase in the Ratio due to decreasing NOx emissions was not obvious as this signal was convolved with variations in the Ratio associated with the temperature dependence of isoprene emissions and, consequently, the formaldehyde concentration

    Association of Upper Gastrointestinal Surgery of Great Britain and Ireland (AUGIS)/Perioperative Quality Initiative (POQI) consensus statement on intraoperative and postoperative interventions to reduce pulmonary complications after oesophagectomy

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    BACKGROUND: Pulmonary complications are the most common morbidity after oesophagectomy, contributing to mortality and prolonged postoperative recovery, and have a negative impact on health-related quality of life. A variety of single or bundled interventions in the perioperative setting have been developed to reduce the incidence of pulmonary complications. Significant variation in practice exists across the UK. The aim of this modified Delphi consensus was to deliver clear evidence-based consensus recommendations regarding intraoperative and postoperative care that may reduce pulmonary complications after oesophagectomy. METHODS: With input from a multidisciplinary group of 23 experts in the perioperative management of patients undergoing surgery for oesophageal cancer, a modified Delphi method was employed. Following an initial systematic review of relevant literature, a range of anaesthetic, surgical, and postoperative care interventions were identified. These were then discussed during a two-part virtual conference. Recommendation statements were drafted, refined, and agreed by all attendees. The level of evidence supporting each statement was considered. RESULTS: Consensus was reached on 12 statements on topics including operative approach, pyloric drainage strategies, intraoperative fluid and ventilation strategies, perioperative analgesia, postoperative feeding plans, and physiotherapy interventions. Seven additional questions concerning the perioperative management of patients undergoing oesophagectomy were highlighted to guide future research. CONCLUSION: Clear consensus recommendations regarding intraoperative and postoperative interventions that may reduce pulmonary complications after oesophagectomy are presented

    The Spectra of T Dwarfs I: Near-Infrared Data and Spectral Classification

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    We present near-infrared spectra for a sample of T dwarfs, including eleven new discoveries made using the Two Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption bands in the 1--2.5 \micron spectral region. A first attempt at a near-infrared classification scheme for T dwarfs is made, based on the strengths of CH4_4 and H2_2O bands and the shapes of the 1.25, 1.6, and 2.1 \micron flux peaks. Subtypes T1 V through T8 V are defined, and spectral indices useful for classification are presented. The subclasses appear to follow a decreasing Teff_{eff} scale, based on the evolution of CH4_4 and H2_2O bands and the properties of L and T dwarfs with known distances. However, we speculate that this scale is not linear with spectral type for cool dwarfs, due to the settling of dust layers below the photosphere and subsequent rapid evolution of spectral morphology around Teff_{eff} ∌\sim 1300--1500 K. Similarities in near-infrared colors and continuity of spectral features suggest that the gap between the latest L dwarfs and earliest T dwarfs has been nearly bridged. This argument is strengthened by the possible role of CH4_4 as a minor absorber shaping the K-band spectra of the latest L dwarfs. Finally, we discuss one peculiar T dwarf, 2MASS 0937+2931, which has very blue near-infrared colors (J-Ks_s = −0.89±-0.89\pm0.24) due to suppression of the 2.1 \micron peak. The feature is likely caused by enhanced collision-induced H2_2 absorption in a high pressure or low metallicity photosphere.Comment: 74 pages including 26 figures, accepted by ApJ v563 December 2001; full paper including all of Table 3 may be downloaded from http://www.gps.caltech.edu/~pa/adam/classification ;also see submission 010844

    Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

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    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew
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