1,542 research outputs found

    A study of marine stratocumulus using lidar and other FIRE aircraft observations

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    The National Center for Atmospheric Research (NCAR) airborne infrared lidar system (NAILS) used in the 1987 First ISCCP Regional Experiment (FIRE) off the coast of California is a 10.6 microns wavelength carbon dioxide lidar system constructed by Ron Schwiesow and co-workers at NCAR. The lidar is particularly well suited for detailed observations of cloud shapes; i.e., height of cloud top (when flying above cloud and looking down) and cloud base (when flying below cloud and looking up) along the flight path. A brief summary of the lidar design characteristics is given. The lidar height resolution of plus or minus 3 m allows for the distance between the aircraft and cloud edge to be determined with this accuracy; however, the duration of the emitted pulse is approximately 3 microseconds, which corresponds to a 500 m pulse length. Therefore, variations in backscatter intensities within the clouds can normally not be resolved. Hence the main parameter obtainable from the lidar is distance to cloud; in some cases the cloud depth can also be determined. During FIRE the lidar was operational on 7 of the 10 Electra flights, and data were taken when the distance between cloud and aircraft (minimum range) was at least 500 m. The lidar was usually operated at 8 Hz, which at a flight speed of 100 m s(-1) translates into a horizontal resolution of about 12 m. The backscatter as function of time (equivalent to distance) for each laser pulse is stored in digital form on magnetic tape. Currently, three independent variables are available to the investigators on the FIRE Electra data tapes: lidar range to cloud, strength of return (relative power), and pulse width of return, which is related to penetration depth

    Infrequent detection of Pneumocystis jirovecii by PCR in oral wash specimens from TB patients with or without HIV and healthy contacts in Tanzania

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    \ud In tuberculosis (TB) endemic parts of the world, patients with pulmonary symptoms are managed as "smear-negative TB patients" if they do not improve on a two-week presumptive, broad-spectrum course of antibiotic treatment even if they are TB microscopy smear negative. These patients are frequently HIV positive and have a higher mortality than smear-positive TB patients. Lack of access to diagnose Pneumocystis jirovecii pneumonia might be a contributing reason. We therefore assessed the prevalence of P. jirovecii by PCR in oral wash specimens among TB patients and healthy individuals in an HIV- and TB-endemic area of sub-Saharan Africa. A prospective study of 384 patients initiating treatment for sputum smear-positive and smear-negative TB and 100 healthy household contacts and neighbourhood controls. DNA from oral wash specimens was examined by PCR for P. jirovecii. All patients delivered sputum for TB microscopy and culture. Healthy contacts and community controls were clinically assessed and all study subjects were HIV tested and had CD4 cell counts determined. Clinical status and mortality was assessed after a follow-up period of 5 months. 384 patients and 100 controls were included, 53% and 8% HIV positive respectively. A total number of 65 patients and controls (13.6%) were at definitive risk for PCP based on CD4 counts <200 cells per mm3 and no specific PCP prophylaxis. Only a single patient (0.3% of the patients) was PCR positive for P. jirovecii. None of the healthy household contacts or neighbourhood controls had PCR-detectable P. jirovecii DNA in their oral wash specimens regardless of HIV-status. The prevalence of P. jirovecii as detected by PCR on oral wash specimens was very low among TB patients with or without HIV and healthy individuals in Tanzania. Colonisation by P. jirovecii was not detected among healthy controls. The present findings may encourage diagnostic use of this non-invasive method

    Stratospheric Gravity Wave Fluxes and Scales during DEEPWAVE

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    During the Deep Propagating Gravity Wave Experiment (DEEPWAVE) project in June and July 2014, the Gulfstream V research aircraft flew 97 legs over the Southern Alps of New Zealand and 150 legs over the Tasman Sea and Southern Ocean, mostly in the low stratosphere at 12.1-km altitude. Improved instrument calibration, redundant sensors, longer flight legs, energy flux estimation, and scale analysis revealed several new gravity wave properties. Over the sea, flight-level wave fluxes mostly fell below the detection threshold. Over terrain, disturbances had characteristic mountain wave attributes of positive vertical energy flux (EFz), negative zonal momentum flux, and upwind horizontal energy flux. In some cases, the fluxes changed rapidly within an 8-h flight, even though environmental conditions were nearly unchanged. The largest observed zonal momentum and vertical energy fluxes were MFx = −550 mPa and EFz = 22 W m−2, respectively. A wide variety of disturbance scales were found at flight level over New Zealand. The vertical wind variance at flight level was dominated by short “fluxless” waves with wavelengths in the 6–15-km range. Even shorter scales, down to 500 m, were found in wave breaking regions. The wavelength of the flux-carrying mountain waves was much longer—mostly between 60 and 150 km. In the strong cases, however, with EFz \u3e 4 W m−2, the dominant flux wavelength decreased (i.e., “downshifted”) to an intermediate wavelength between 20 and 60 km. A potential explanation for the rapid flux changes and the scale “downshifting” is that low-level flow can shift between “terrain following” and “envelope following” associated with trapped air in steep New Zealand valleys

    Phenotypic and genotypic antimicrobial susceptibility patterns of the emerging human respiratory pathogen Mycoplasma amphoriforme isolated from the UK and Denmark

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    Methods Seven isolates of M. amphoriforme were examined for antimicrobial susceptibility to seven antibiotics using the microbroth dilution assay in line with the CLSI guidelines for mycoplasmas. Each isolate was additionally subjected to WGS to identify resistance-associated mutations. Based on the consensus sequences from the genomic data, PCR primers were designed, and tested, for the amplification of the QRDR within the parC gene. Results Of the seven isolates investigated, four (57%) were resistant to moxifloxacin (0.5–1 mg/L) and levofloxacin (1–2 mg/L), compared with those that were susceptible (0.03–0.06 and 0.006 mg/L, respectively). Isolate H29 was resistant to five of the seven antibiotics tested: moxifloxacin, 0.5 mg/L; levofloxacin, 2 mg/L; azithromycin, 64 mg/L; erythromycin, 128 mg/L; and clindamycin, 64 mg/L. All isolates were susceptible to tetracycline (0.06 mg/L) and lefamulin (0.001–0.004 mg/L). Mutations from genomic data confirmed the presence of an S89F mutation within the ParC protein among all fluoroquinolone-resistant isolates and an A2059G mutation in the 23S rRNA gene in the macrolide- and lincosamide-resistant isolate H29. Conclusions To the best of our knowledge, this is the first time where phenotypic and genotypic resistance data have been paired for M. amphoriforme confirming a correlation between the two. These data suggest the need for focused testing and resistance determination of isolates from high-risk patients given the backdrop of a high prevalence of antimicrobial resistance

    GDF15 Provides an Endocrine Signal of Nutritional Stress in Mice and Humans.

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    GDF15 is an established biomarker of cellular stress. The fact that it signals via a specific hindbrain receptor, GFRAL, and that mice lacking GDF15 manifest diet-induced obesity suggest that GDF15 may play a physiological role in energy balance. We performed experiments in humans, mice, and cells to determine if and how nutritional perturbations modify GDF15 expression. Circulating GDF15 levels manifest very modest changes in response to moderate caloric surpluses or deficits in mice or humans, differentiating it from classical intestinally derived satiety hormones and leptin. However, GDF15 levels do increase following sustained high-fat feeding or dietary amino acid imbalance in mice. We demonstrate that GDF15 expression is regulated by the integrated stress response and is induced in selected tissues in mice in these settings. Finally, we show that pharmacological GDF15 administration to mice can trigger conditioned taste aversion, suggesting that GDF15 may induce an aversive response to nutritional stress.This work and authors were funded by the NIHR Cambridge Biomedical Research Centre; NIHR Rare Disease Translational Research Collaboration; Medical Research Council [MC_UU_12012/2 and MRC_MC_UU_12012/3]; MRC Metabolic Diseases Unit [MRC_MC_UU_12012/5 and MRC_MC_UU_12012.1]; Wellcome Trust Strategic Award [100574/Z/12/Z and 100140]; Wellcome Trust [107064 , 095515/Z/11/Z , 098497/Z/12/Z, 106262/Z/14/Z and 106263/Z/14/Z]; British Heart Foundation [RG/12/13/29853]; Addenbrooke’s Charitable Trust / Evelyn Trust Cambridge Clinical Research Fellowship [16-69] US Department of Agriculture: 2010-34323-21052; EFSD project grant and a Royal College of Surgeons Research Fellowship, Diabetes UK Harry Keen intermediate clinical fellowship (17/0005712). European Research Council, Bernard Wolfe Health Neuroscience Endowment, Experimental Medicine Training Initiative/AstraZeneca and Medimmune

    EuropeaN Energy balance Research to prevent excessive weight Gain among Youth (ENERGY) project: Design and methodology of the ENERGY cross-sectional survey

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    Background: Obesity treatment is by large ineffective long term, and more emphasis on the prevention of excessive weight gain in childhood and adolescence is warranted. To inform energy balance related behaviour (EBRB) change interventions, insight in the potential personal, family and school environmental correlates of these behaviours is needed. Studies on such multilevel correlates of EBRB among schoolchildren in Europe are lacking. The ENERGY survey aims to (1) provide up-to-date prevalence rates of measured overweight, obesity, self-reported engagement in EBRBs, and objective accelerometer-based assessment of physical activity and sedentary behaviour and blood-sample biomarkers of metabolic function in countries in different regions of Europe, (2) to identify personal, family and school environmental correlates of these EBRBs. This paper describes the design, methodology and protocol of the survey. Method/Design: A school-based cross-sectional survey was carried out in 2010 in seven different European countries; Belgium, Greece, Hungary, the Netherlands, Norway, Slovenia, and Spain. The survey included measurements of anthropometrics, child, parent and school-staff questionnaires, and school observations to measure and assess outcomes (i.e. height, weight, and waist circumference), EBRBs and potential personal, family and school environmental correlates of these behaviours including the social-cultural, physical, political, and economic environmental factors. In addition, a selection of countries conducted accelerometer measurements to objectively assess physical activity and sedentary behaviour, and collected blood samples to assess several biomarkers of metabolic function. Discussion: The ENERGY survey is a comprehensive cross-sectional study measuring anthropometrics and biomarkers as well as assessing a range of EBRBs and their potential correlates at the personal, family and school level, among 10-12 year old children in seven European countries. This study will result in a unique dataset, enabling cross country comparisons in overweight, obesity, risk behaviours for these conditions as well as the correlates of engagement in these risk behaviours

    Use of Carboxymethyl Cellulose and Collagen Carrier with Equine Bone Lyophilisate Suggests Late Onset Bone Regenerative Effect in a Humerus Drill Defect – A Pilot Study in Six Sheep

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    We assessed the use of a filler compound together with the osteoinductive demineralized bone matrix (DBM), Colloss E. The filler was comprised of carboxymethyl-cellulose and collagen type 1. The purpose of the study was to see if the filler compound would enhance the bone formation and distribute the osteoinductive stimulus throughout the bone defect. Six sheep underwent a bilateral humerus drill defect. The drill hole was filled with a compound consisting of 100 mg CMC, 100 mg collagen powder, and 1 ccm autologous full blood in one side, and a combination of this filler compound and 20 mg Colloss E in the other. The animals were divided into three groups of two animals and observed for 8, 12 and 16 weeks. Drill holes was evaluated using quantitative computed tomography (QCT), micro computed tomography (”CT) and histomorphometry. Mean total bone mineral density (BMD) of each implantation site was calculated with both QCT and ”CT. Bone volume to total volume (BV/TV) was analyzed using ”CT and histomorphometry. Although not statistically significant, results showed increased bone BMD after 16 weeks in ”CT data and an increased BV/TV after 16 weeks in both ”CT and histology. Correlation between QCT and ”CT was R2 = 0.804. Correlation between histomorphometry and ”CT BV/TV data was R2 = 0.8935 and with an average overrepresentation of 8.2% in histomorphometry. In conclusion the CMC-Collagen + Colloss E filler seems like a viable osteogenic bone filler mid- to long term. A correlation was found between the analytical methods used in this study
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