925 research outputs found

    Measures of Niche Overlap, I

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    Many methods of measuring niche overlap have been proposed, such as those of Renkonen, Morisita, and Horn. In this paper, conditions are put forward which overlap indices should reasonably be expected to satisfy. A general description of a good index is given, which covers as special cases those of the well-known indices which satisfy all the conditions. A mixture of the Renkonen and van Belle & Ahmad indices is suggested, as it has many desirable properties. The problem of estimating overlap from data is discussed briefl

    Monitoring Sarcomere Structure Changes in Whole Muscle Using Diffuse Light Reflectance

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    doi:10.1117/1.2234278Normal biomechanical and physiological functions of striated muscles are facilitated by the repeating sarcomere units. Light scattering technique has been used in studying single extracted muscle fibers. However, few studies, if any, have been conducted to investigate the possibility of using optical detection to examine sarcomere structure changes in whole muscles. We conducted a series of experiments to demonstrate that optical scattering properties measured in whole muscle are related to changes in sarcomere structure. These results suggest that photon migration technique has a potential for characterizing in vivo tissue ultrastructure changes in whole muscle

    Oxygen ion dynamics in the Earth's ring current: Van Allen probes observations

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    Oxygen (O+) enhancements in the inner magnetosphere are often observed during geomagnetically active times, such as geomagnetic storms. In this study, we quantitatively examine the difference in ring current dynamics with and without a substantial O+ ion population based on almost 6 years of Van Allen Probes observations. Our results have not only confirmed previous finding of the role of O+ ions to the ring current but also found that abundant O+ ions are always present during large storms when sym-H < -60 nT without exception, whilst having the pressure ratio () between O+ and proton (H+) larger than 0.8 and occasionally even larger than 1 when L < 3. Simultaneously, the pressure anisotropy decreases with decreasing sym-H and increasing L shell. The pressure anisotropy decrease during the storm main phase is likely related to the pitch angle isotropization processes. In addition, we find that increases during the storm main phase and then decreases during the storm recovery phase, suggesting faster buildup and decay of O+ pressure compared to H+ ions, which are probably associated with some species dependent source and/or energization as well as loss processes in the inner magnetosphere.Accepted manuscrip

    The archaeology of a landslide: Unravelling the Azores earthquake disaster of 1522 and its consequences

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    The multidisciplinary research described here shows how archaeologists can help reconstruct past seismic episodes and understand the subsequent relief operation, rehabilitation, and reconstruction processes. In October 1522, a major earthquake and landslide struck the then capital of the Azores, Vila Franca do Campo, 1500 km from the European mainland. Damage was extensive, destroying key monuments, affecting most of the inhabited area, and leaving few survivors among the early colonists. The results from twenty-six archaeological trenches, geological and geoarchaeological investigations, and documentary analysis are reviewed here. Distinctive archaeological deposits are identified and explained, using the high density of artefacts and the erosional contact between the landslide and the pre-1522 palaeosol to reconstruct the episode in detail

    Comparing media and family predictors of alcohol use: a cohort study of US adolescents

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    Objective: To compare media/marketing exposures and family factors in predicting adolescent alcohol use. Design: Cohort study. Setting: Confidential telephone survey of adolescents in their homes. Participants: Representative sample of 6522 US adolescents, aged 10–14 years at baseline and surveyed four times over 2 years. Primary: outcome measure Time to alcohol onset and progression to binge drinking were assessed with two survival models. Predictors were movie alcohol exposure (MAE), ownership of alcohol-branded merchandise and characteristics of the family (parental alcohol use, home availability of alcohol and parenting). Covariates included sociodemographics, peer drinking and personality factors. Results: Over the study period, the prevalence of adolescent ever use and binge drinking increased from 11% to 25% and from 4% to 13%, respectively. At baseline, the median estimated MAE from a population of 532 movies was 4.5 h and 11% owned alcohol-branded merchandise at time 2. Parental alcohol use (greater than or equal to weekly) was reported by 23% and 29% of adolescents could obtain alcohol from home. Peer drinking, MAE, alcohol-branded merchandise, age and rebelliousness were associated with both alcohol onset and progression to binge drinking. The adjusted hazard ratios for alcohol onset and binge drinking transition for high versus low MAE exposure were 2.13 (95% CI 1.76 to 2.57) and 1.63 (1.20 to 2.21), respectively, and MAE accounted for 28% and 20% of these transitions, respectively. Characteristics of the family were associated with alcohol onset but not with progression. Conclusion: The results suggest that family focused interventions would have a larger impact on alcohol onset while limiting media and marketing exposure could help prevent both onset and progression

    ArMedEa project: archaeology of medieval earthquakes in Europe (1000-1550 AD). First research activities

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    This paper introduces the research of the Armedea project. Armedea (Archaeology of medieval earthquakes in Europe, 1000-1550 AD) is a medieval archaeology project undertaken at the Department of Archaeology of Durham University which analyses archaeological evidence related to late medieval seismic-affected contexts at a European scale. This project is therefore focused on both earthquake effects on archaeological sites, their standing buildings and environment, and the archaeological evidence that reveals the response of medieval societies in terms of risk reduction, protection and resilience. A first preview of GIS analysis of seismic activity impact on medieval societies and fieldwork activities carried out in Italy, Cyprus and Azores (Portugal) is presented here. This research is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme

    An assessment of infant medication administration and storage practices in selected communities in the Vhembe District of Limpopo Province, South Africa

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    Background: Effective infant medication administration and storage is a major public health challenge outlined by the World Health Organization. These challenges may be exacerbated in rural or limited-resource areas. Aim: The aim of this study was to investigate infant medication administration and storage practices. Setting: This study took place in selected communities in the Vhembe District of Limpopo Province, South Africa. Method: Data was collected through 39 semi-structured interviews with infant caretakers and rural health workers. Interviews were recorded when permission was given by participants. Interviews were transcribed and coded using grounded theory and Tesch’s model of data analysis. Themes were agreed upon through consensus discussions with the researchers and an independent coder. Results: Six themes that affect current infant medication administration and storage practices in the Vhembe District were identified: access to infant healthcare, the role of health workers, the devices used in the administration of infant medication, reluctance of the infant to take the medication, storage and reuse of infant medication in the rural home and hygiene practices surrounding infant medication administration. Conclusions: Many factors were found to affect infant medication administration and storage practices in in the Vhembe District. Substantial evidence was found to suggest that the relationship between rural health workers and infant caretakers strongly influences these practices: a great amount of reliance and trust is placed in the health worker. Ensuring proper dosage of infant medication in the rural household arose as a main concern of participants. Reuse of medication in the home and home hygiene practices surrounding infant medication administration are areas of potential future research. This future research may further inform recommendations for infant medication administration and storage practices in the Vhembe District

    Alternative tissue fixation for combined histopathological and molecular analysis in a clinically representative setting

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    Formalin is the principal tissue fixative used worldwide for clinical and research purposes. Despite optimal preservation of morphology, its preservation of DNA and RNA is poor. As clinical diagnostics increasingly incorporates molecular-based analysis, the requirement for maintaining nucleic acid quality is of increasing importance. Here we assess an alternative non-formalin-based tissue fixation method, PAXgene Tissue system, with the aim of better preserving nucleic acids, while maintaining the quality of the tissue to be used for vital existing diagnostic techniques. In this study, these criteria are assessed in a clinically representative setting. In total, 203 paired PAXgene Tissue and formalin-fixed samples were obtained. Blind-scored haematoxylin and eosin (H&E) sections showed comparable and acceptable staining. Immunohistochemistry (IHC) staining was suboptimal using existing protocols but improved with minor method adjustment and optimisation. Quality of DNA and RNA was significantly improved by PAXgene tissue fixation [RIN 2.8 versus 3.8 (p < 0.01), DIN 5.68 versus 6.77 (p < 0.001)], which translated into improved performance on qPCR assay. These results demonstrate the potential of PAXgene Tissue to be used routinely in place of formalin, maintaining adequate histological staining and significantly improving the preservation of biological molecules in the genomic era
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