660 research outputs found

    Radiative cooler

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    A method and radiative cooling device for use in passively cooling spaces is described. It is applicable to any level of thermal radiation in vacuum and to high-intensity thermal radiation in non-vacuum environments. The device includes an enclosure nested in a multiplicity of thin, low-emittance, highly-reflective shields. The shields are suspended in a casing in mutual angular relation and having V-shaped spaces defined therebetween for redirecting, by reflection, toward the large openings of the V-shaped spaces, thermal radiation entering the sides of the shields, and emitted to the spaces, whereby successively reduced quantities of thermal radiation are reflected by the surfaces along substantially parallel paths extended through the V-shaped spaces to a common heat sink such as the cold thermal background of space

    An Investigation of Selected Factors on Golfer Attachment

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    While little change has occurred in the total number of golfers in the United States, the total number of golf courses is rapidly increasing (3). This increase in market competition has made it vital for resort owners and managers to examine the variables which influence golfers to use and return to their facilities. A relationship that appears to form between golfers and golf courses which has been neglected is place attachment. The purpose of this study was to examine whether or not place attachment actually occurs on a golf course. A second purpose was to investigate the relationship between attachment and a golfer\u27s proximity to the course, gender, age, frequency of play, handicap and income. A third purpose was to examine the relationship between attachment to course and overall satisfaction and perceived value. Subjects (N=l,397) were randomly selected by tee times stratified by weekday and weekend and season of the year at six different Cleveland Metro Parks golf courses. Of the golfers that participated, the average age was 49.9, 70.2% were married, 79.9% were male, and the median household income was 50,000to50,000 to 59,999. Results show that a distinct variable of attachment emerged from golfers\u27 perceptions. Further, age, frequency of play, perceived value and overall satisfaction were all found to have strong relationships to attachment. Managerial implications and applicability are discussed

    Obstacles to the Revival of Mobile Grazing Systems in Kazakhstan

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    Livestock mobility was an essential characteristic of Kazakh livestock production systems, allowing animals to take advantage of spatial and temporal variability in climate and vegetation, optimising forage intake over the year. These systems broke down following the end of the Soviet Union. In this paper we examine the extent and determinants of the recovery of mobile livestock husbandry in south-eastern Kazakhstan, using surveys and semi-structured interviews with livestock farmers and rural households (holding livestock but not registered as farms). We find positive relationships between livestock holding size and probability of mobility. Winter pastures are particularly important for large farms, with households and smaller farms more dependent on supplementary fodder. The major formal property right over pasture is the long-term leasehold, allocated by auction and associated with significant transaction costs. Leasehold markets function poorly, so farms use a combination of leasing, subleasing and short-term contracts with local authorities to assemble the pastoral resources they need. Few farmers conduct more than a simplified summer-winter migration, whilst around 30% of farms and 70% of households (which own the bulk of livestock) are entirely sedentary, staying on over-used village pastures all year round. Many of these producers express a desire for improved pasture access. The 2017 Law on Pastures introduced district-level pasture use planning, with promotion of mobility and allocation of remote pastures to those with poor access. But the Law does not include new land tenure mechanisms appropriate for small producers (owning few livestock and without leaseholds) which can be employed to realise this goal. Moreover, most pastures are already leased. We discuss options for grazing system management which may simultaneously increase the economic contribution of pastures, improve their condition and reduce rural inequalities created by disparities in access to resources

    Salivary Metabolomic Signatures and Body Mass Index in Italian Adolescents: A Pilot Study

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    Context: Obesity surveillance is scarce in adolescents, and little is known on whether salivary metabolomics data, emerging minimally invasive biomarkers, can characterize metabolic patterns associated with overweight or obesity in adolescents. Objective: This pilot study aims to identify the salivary molecular signatures associated with body mass index (BMI) in Italian adolescents. Methods: Saliva samples and BMI were collected in a subset of n = 74 young adolescents enrolled in the Public Health Impact of Metal Exposure study (2007-2014). A total of 217 untargeted metabolites were identified using liquid chromatography-high resolution mass spectrometry. Robust linear regression was used to cross-sectionally determine associations between metabolomic signatures and sex-specific BMI-for-age z-scores (z-BMI). Results: Nearly 35% of the adolescents (median age: 12 years; 51% females) were either obese or overweight. A higher z-BMI was observed in males compared to females (P = .02). One nucleoside (deoxyadenosine) and 2 lipids (18:0-18:2 phosphatidylcholine and dipalmitoyl-phosphoethanolamine) were negatively related to z-BMI (P < .05), whereas 2 benzenoids (3-hydroxyanthranilic acid and a phthalate metabolite) were positively associated with z-BMI (P < .05). In males, several metabolites including deoxyadenosine, as well as deoxycarnitine, hyodeoxycholic acid, N-methylglutamic acid, bisphenol P, and trigonelline were downregulated, while 3 metabolites (3-hydroxyanthranilic acid, theobromine/theophylline/paraxanthine, and alanine) were upregulated in relation to z-BMI (P < .05). In females, deoxyadenosine and dipalmitoyl-phosphoethanolamine were negatively associated with z-BMI while deoxycarnitine and a phthalate metabolite were positively associated (P < .05). A single energy-related pathway was enriched in the identified associations in females (carnitine synthesis, P = .04). Conclusion: Salivary metabolites involved in nucleotide, lipid, and energy metabolism were primarily altered in relation to BMI in adolescents

    Measurements of total odd nitrogen (NOy) aboard MOZAIC in-service aircraft: instrument design, operation and performance

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    A small system for the unattended measurement of total odd nitrogen (NOy, i.e., the sum of NO and its atmospheric oxidation products) aboard civil in-service aircraft in the framework of MOZAIC is described. The instrument employs the detection of NO by its chemiluminescence with O-3 in combination with catalytic conversion of the other NOy compounds to NO at 300degreesC on a gold surface in the presence of H-2. The instrument has a sensitivity of 0.4-0.7 cps/ppt and is designed for unattended operation during 1-2 service cycles of the aircraft (400-800 flight hours). The total weight is 50 kg, including calibration system, compressed gases, mounting, and safety measures. The layout and inlet configuration are governed by requirements due to the certification for passenger aircraft. Laboratory tests are described regarding the conversion efficiency for NO2 and HNO3 (both > 98%). Interference by non-NOy species is <1% for CH3CN and NH3, <5 x 10(-5) % for N2O (corresponding to <0.2 ppt fake NOy from ambient N2O) and 100% for HCN. The time response of the instrument is <1 s (90% change) for NO2. The response for HNO3 is nonlinear: 20 s for 67%, 60 s for 80%, and 150 s for 90% response, respectively

    Effectiveness of Internal vs. External SEU Scrubbing Mitigation Strategies in a Xilinx FPGA: Design, Test, and Analysis

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    We compare two scrubbing mitigation schemes for Xilinx FPGA devices. The design of the scrubbers is briefly discussed along with an examination of mitigation limitations. Proton and Heavy Ion data are then presented and analyzed

    Demographic, Clinical, and Behavioral Determinants of 7-Year Weight Change Trajectories in Roux-en-Y Gastric Bypass Patients.

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    BACKGROUND: Weight change trajectories after weight-loss surgery may vary significantly. OBJECTIVES: This study evaluated the weight trajectories of Roux-en-Y gastric bypass (RYGB) patients and identified the distinct clinical, behavioral, and demographic features of patients by trajectory. SETTING: Data from 2918 RYGB patients from a comprehensive medical center between January 2004 and November 2016 were included. METHODS: This retrospective, observational study used data for RYGB patients up to year 7 postsurgery. Group-based trajectory models were fitted for percentage weight change. Variables evaluated by trajectory included age, sex, diagnoses, medications, smoking, presurgical body mass index, preoperative weight loss, and early postoperative weight loss. RESULTS: Of 3215 possible patients, 2918 (90.8%) were included (mean age = 46.2 ± 11.2 yr, body mass index = 46.9 ± 7.9 kg/m CONCLUSION: Select clinical, demographic, and behavioral factors may increase or decrease the chance for better weight loss after RYGB

    Comparing two correlated C indices with right-censored survival outcome: a one-shot nonparametric approach

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    The area under the receiver operating characteristic curve is often used as a summary index of the diagnostic ability in evaluating biomarkers when the clinical outcome (truth) is binary. When the clinical outcome is right-censored survival time, the C index, motivated as an extension of area under the receiver operating characteristic curve, has been proposed by Harrell as a measure of concordance between a predictive biomarker and the right-censored survival outcome. In this work, we investigate methods for statistical comparison of two diagnostic or predictive systems, of which they could either be two biomarkers or two fixed algorithms, in terms of their C indices. We adopt a U-statistics-based C estimator that is asymptotically normal and develop a nonparametric analytical approach to estimate the variance of the C estimator and the covariance of two C estimators. A z-score test is then constructed to compare the two C indices. We validate our one-shot nonparametric method via simulation studies in terms of the type I error rate and power. We also compare our one-shot method with resampling methods including the jackknife and the bootstrap. Simulation results show that the proposed one-shot method provides almost unbiased variance estimations and has satisfactory type I error control and power. Finally, we illustrate the use of the proposed method with an example from the Framingham Heart Study

    The influence of iron status and genetic polymorphisms in the HFE gene on the risk for postoperative complications after bariatric surgery: a prospective cohort study in 1,064 patients

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    <p>Abstract</p> <p>Background</p> <p>Gastric bypass surgery is a highly effective therapy for long-term weight loss in severely obese patients, but carries significant perioperative risks including infection, wound dehiscence, and leaks from staple breakdown. Iron status can affect immune function and wound healing, thus may influence peri-operative complications. Common mutations in the HFE gene, the gene responsible for the iron overload disorder hereditary hemochromatosis, may impact iron status.</p> <p>Methods</p> <p>We analyzed 1064 extremely obese Caucasian individuals who underwent open and laparoscopic Roux-n-Y gastric bypass surgery at the Geisinger Clinic. Serum iron, ferritin, transferrin, and iron binding capacity were measured pre-operatively. All patients had intra-operative liver biopsies and were genotyped for the C282Y and H63D mutations in the HFE gene. Associations between surgical complications and serum iron measures, HFE gene status, and liver iron histology were determined.</p> <p>Results</p> <p>We found that increased serum iron and transferrin saturation were present in patients with any post-operative complication, and that increased serum ferritin was also increased in patients with major complications. Increased serum transferrin saturation was also associated with wound complications in open RYGB, and transferrin saturation and ferritin with prolonged lengths of stay. The presence of 2 or more HFE mutations was associated with overall complications as well as wound complications in open RYGB. No differences were found in complication rates between those with stainable liver iron and those without.</p> <p>Conclusion</p> <p>Serum iron status and HFE genotype may be associated with complications following RYGB surgery in the extremely obese.</p

    Obesity, diabetes, serum glucose, and risk of primary liver cancer by birth cohort, race/ethnicity, and sex: Multiphasic health checkup study

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    Obesity and diabetes have been associated with liver cancer. However, recent US-based studies have suggested a lack of association between obesity and liver cancer among blacks and women
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