1,441 research outputs found

    Multi-Sensor Calibration and Validation of the UWO-PCL Water Vapour Lidar

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    The Purple Crow Lidar (PCL) has recently participated in a water vapour validation cam- paign with the NASA/GSFC Atmospheric Laboratory for Validation/Interagency Collaboration and Education (ALVICE) Lidar. The purpose of this calibration campaign is to insure that PCL water vapour measurements are of sufficient quality for use in scientific investigations of atmo- spheric change, and to be included in the Network for the Detection of Atmospheric Climate Change (NDACC) data base. The detection of long term changes in water vapour concentra- tion, particularly in the upper troposphere and lower stratosphere (UTLS) is an issue of pressing scientific, ecological and societal concern. The field campaign took place at the University of Western Ontario Environmental Re- search Field Station, near London Ontario Canada, from May 23rd to June 10th 2012 and resulted in 57 hours of measurements taken over 12 clear nights. On each night a minimum of one RS92 radiosonde was launched. In addition 3 cryogenic frost-point hygrometer (CFH) sondes were launched on clear nights over the course of the campaign. Measurements were obtained from near the surface up to āˆ¼20 km by both lidar systems, the radiosondes, and the CFH balloons. These measurements will be used to calibrate profiles of water vapour mixing ratio by the newly relocated PCL. Comparisons between measurements of water vapour mass mixing ratio taken by RS92 ra- diosondes, Cryogenic Frostpoint Hygometers, and the ALVICE and PCL lidars has resulted in the derivation of a system calibration factor of Ī¾ sys = 0.7545. The application of this calibration factor to PCL retrievals has allowed for the validation of PCL water vapour mass mixing ratio profiles to within Ā±5% between the altitudes of 2 km and 9 km

    Differential localization of IcsA and IcsP in the outer membrane of Shigella flexneri

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    Our goal is to visualize IcsP on the surface of S. flexneri and determine how its localization changes during growth versus stationary phases. We hypothesize IcsP will be present on the surface of S. flexneri differentially during growth and stationary phases of cell cycle. We hypothesize greater levels of IcsP seen during stationary phase (simultaneous with lower, more unipolar IcsA, due to IcsP mediated cleavage). During growth phase, we expect less IcsP to be present on the surface, and IcsA to be more evenly distributed around the cell surface

    P07. Characterizing the Purple Crow Lidar to investigate potential sources of wet bias

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    The Purple Crow Lidar is a large aperture lidar, capable of retrieving water vapor profiles into the stratosphere. Water vapor in the upper Troposphere-Lower Stratosphere (UTLS) region is of particular importance in understanding Earth\u27s radiative budget and atmospheric dynamics, making accurate UTLS measurements crucial. A comparison campaign with the NASA/GSFC ALVICE mobile lidar in the spring of 2012 showed PCL water vapor measurements were consistently larger than those of ALVICE in the lower stratosphere, prompting an investigation to characterize the system. The investigation looks into how changes to the data processing approach, as well as applying additional instrumental corrections, would affect the water vapor mixing ratio. We also look into a retrieval of the mixing ratio using optimal estimation method (OEM), which should provide greater insight into the associated data processing parameters and uncertainties

    Complex Basal Thermal Transition Near the Onset of Petermann Glacier, Greenland

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    The basal thermal regime of ice sheets exerts a strong control on iceā€sheet stability and the onset of rapidly streaming flow. However, the nature of this thermal transition where sliding initiates is largely unconstrained by geophysical observations. In the Greenland Ice Sheet, topographic troughs or elevated geothermal heat fluxes typically define the onset of outlet glaciers. In contrast, Petermann Glacier in Northern Greenland does not have any distinct bed troughs or localized geothermal heating associated with its onset, making it an ideal site to investigate the basal thermal state and examine its role in the onset of Petermann Glacier. Here we use radar bed reflectivity and an iceā€sheet thermomechanical model to examine the basal thermal regime beneath Petermann Glacier. Our results reveal a complex thermal transition near the onset of Petermann Glacier. As the bed shifts from largely frozen to largely thawed with increasing distances from the ice divide, our results show that this thermal transition happens through alternating bands of frozen and thawed bands. The complex thermal state across the onset region suggests that lateral meltwater injection and local meltwater production determine the location of Petermann Glacier. Given the lack of topographic pinning at the onset location, the upstream margin of Petermann is vulnerable to migrate depending on a combination of advective cooling and meltwater supply from the interior of the ice sheet

    Free-living dietary intake in tactical personnel and implications for nutrition practice: a systematic review

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    Tactical personnel (including military, law enforcement, and fire and rescue) are responsible for ensuring national and public safety. Dietary intake is an important consideration to support optimal health and performance. The aims of this systematic review were to: (1) describe the reported free-living dietary intake (energy and macronutrients) of tactical personnel, and (2) describe the practical implications of reported dietary intakes to support the physical and dietary requirements of tactical personnel. A systematic search of databases (MEDLINE, EMBASE, CINAHL and Web of Science) was conducted following the PRISMA guidelines. English and full text research articles were identified and screened against inclusion and exclusion criteria. Demographic and dietary intake data were extracted, tabulated, and synthesized narratively. The quality of the studies was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Twenty-two studies (15 military, 4 law enforcement, and 2 fire and rescue) were eligible to inform this review. The volume of evidence suggested that tactical personnel met dietary protein and exceeded dietary fat recommendations but failed to meet energy and carbohydrate recommendations. Therefore, practical approaches to support optimized energy, fat and carbohydrate intake in tactical personnel is important

    Rerouting of subglacial water flow between neighboring glaciers in West Greenland

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    Investigations of the Greenland ice sheet's subglacial hydrological system show that the connectivity of different regions of the system influences how the glacier velocity responds to variations in surface melting. Here we examine whether subglacial water flow paths can be rerouted beneath three outlet glaciers in the ablation zone of western Greenland. We use Lamont-Doherty and Center for Remote Sensing of Ice Sheets of University of Kansas (CReSIS) ice-penetrating radar data to create a new ice thickness map. We then use a simple subglacial water flow model to examine whether flow paths can be rerouted and identify the topographic conditions that are sensitive to subglacial rerouting. By varying water pressures within an observationally constrained range, we show that moderate changes in pressure can cause flow paths to reroute and exchange water from one subglacial catchment to another. Flow across subglacial overdeepenings is particularly sensitive to rerouting. These areas have low hydraulic gradients driving flow, so subtle water pressure variations have a strong influence on water flow direction. Based on correlations between water flow paths and ice velocity changes, we infer that water piracy between neighboring catchments can result in a different spatial pattern of hydrologically induced ice velocity speedup depending on the amount and timing of surface melt. The potential for subglacial water to reroute across different catchments suggests that multiple hydrographs from neighboring glaciers are likely necessary to accurately ascertain melt budgets from proglacial point measurements. The relationship between surface runoff, ice dynamics, and proglacial discharge can be altered by rerouting of subglacial water flow within and across outlet glaciers

    Variations of Infiltration and Electronic Contact in Mesoscopic Perovskite Solar Cells Revealed by Highā€Resolution Multiā€Mapping Techniques

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    A combination of highā€resolution mapping techniques is developed to probe the homogeneity and defects of mesoscopic perovskite solar cells. Three types of cells using a oneā€step infiltration process with methylammonium lead iodide (MAPbI3) or 5ā€ammoniumvaleric acidā€MAPbI3 solutions, or twoā€step process with MAPbI3 solution are investigated. The correlation between photoluminescence, photocurrent, electroluminescence, and Raman maps gives a detailed understanding of the different infiltration mechanisms, electronic contact at interfaces, and effect on local photocurrent for the cells. The oneā€step MAPbI3 cell has very limited infiltration of the perovskite solution which results in poor device performance. High loading of the mesopores of the TiO2 and ZrO2 scaffold is observed when using 5ā€ammoniumvaleric acid, but some micrometerā€sized nonā€infiltrated areas remain due to dense carbon flakes hindering perovskite infiltration. The twoā€step cell has a complex morphology with features having either beneficial or detrimental effects on the local photocurrent. The results not only provide key insights to achieving better infiltration and homogeneity of the perovskite film in mesoporous devices but can also aid further work on planar devices to develop efficient extraction layers. Moreover, this multiā€mapping approach allows the correlation of the local photophysical properties of full perovskite devices, which would be challenging to obtain by other techniques

    Exploration of Work and Health Disparities among Black Women Employed in Poultry Processing in the Rural South

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    We describe an ongoing collaboration that developed as academic investigators responded to a specific request from community members to document health effects on black women of employment in poultry-processing plants in rural North Carolina. Primary outcomes of interest are upper extremity musculoskeletal disorders and function as well as quality of life. Because of concerns of community women and the history of poor labor relations, we decided to conduct this longitudinal study in a manner that did not require involvement of the employer. To provide more detailed insights into the effects of this type of employment, the epidemiologic analyses are supplemented by ethnographic interviews. The resulting approach requires community collaboration. Community-based staff, as paid members of the research team, manage the local project office, recruit and retain participants, conduct interviews, coordinate physical assessments, and participate in outreach. Other community members assisted in the design of the data collection tools and the recruitment of longitudinal study participants and took part in the ethnographic component of the study. This presentation provides an example of one model through which academic researchers and community members can work together productively under challenging circumstances. Notable accomplishments include the recruitment and retention of a cohort of low-income rural black women, often considered hard to reach in research studies. This community-based project includes a number of elements associated with community-based participatory research

    Sport-related concussion practices of medical team staff in elite football in the United Kingdom, a pilot study

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    Objectives: To explore sport-related concussion (SRC) awareness, behaviours, and attitudes of medical team staff working in elite football in the United Kingdom. Including usage and awareness of the FA concussion guidelines, concussion education rates of players and coaching staff, and collection of baseline concussion assessments. Methods: Cross-sectional questionnaire study distributed online by organisations including or representing medical staff working in elite football in the United Kingdom. Results: 120 responses were gathered. High awareness rates of the FA guidelines were found (97%) with variable rates of player and coaching staff concussion education. Baseline concussion assessments were collected by 78%. Of those, 99% collected SCAT5 with low rates of other neuro-psychometric testing (17%). Confidence of pitch-side SRC recognition was high (93% feeling very confident or confident). Introduction of a ā€˜concussionā€™ substitute was seen as strongly positive for player welfare (85% strongly agreeing or agreeing). Conclusions: Awareness of FA concussion guidelines, and collection of SCAT5 baseline testing was high. Player and coaching staff concussion education rates were low, as was the use of neuro-psychometric testing beyond the use of the SCAT5. There was strong support the introduction of a ā€˜concussionā€™ substitute being a positive thing for player welfare

    Sport-related concussion return-to-play practices of medical team staff in elite football in the United Kingdom

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    This study explored sport-related concussion (SRC) return-to-play (RTP) behaviours and attitudes of medical team staff working in elite football in the United Kingdom. Usage and awareness of The Football Association (FA) guidelines, concussion education rates of players and coaching staff, and collection of baseline concussion assessments. Additionally, confidence in managing RTP post-SRC, perceived player under-reporting of symptoms, use of enhanced RTP pathways, and coaching pressure on RTP were investigated. A cross-sectional questionnaire study was distributed online by organisations including or representing medical staff working in elite football in the United Kingdom. A total of 112 responses were gathered. High awareness rates of the FA guidelines were found (96%) with variable rates of player and coaching staff concussion education. Baseline concussion assessments were collected by 80% of respondents with 93% feeling very confident or confident in managing the RTP of a player with a SRC. 60% rarely or never experienced coaching pressure around player RTP, and 24% felt players always or very often under-reported symptoms to expedite their return. 90% had a moderate to high confidence in the Sport Concussion Assessment Tool-5 (SCAT-5) as a RTP decision tool, and 66% always or very often used an enhanced RTP pathway. Confidence in managing player RTP post SRC and use of enhanced RTP pathways were high, as was confidence in the SCAT-5 as a RTP decision tool. Respondents raised concerns around player under-reporting of symptoms to accelerate RTP post-SRC, and perceived coaching pressure around decision making
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