259 research outputs found

    US East Coast lidar measurements show offshore wind turbines will encounter very low atmospheric turbulence

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    © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bodini, N., Lundquist, J. K., & Kirincich, A. US East Coast lidar measurements show offshore wind turbines will encounter very low atmospheric turbulence. Geophysical Research Letters, 46(10), (2019):5582-5591, doi:10.1029/2019GL082636.The rapid growth of offshore wind energy requires accurate modeling of the wind resource, which can be depleted by wind farm wakes. Turbulence dissipation rate (ϵ) governs the accuracy of model predictions of hub‐height wind speed and the development and erosion of wakes. Here we assess the variability of turbulence kinetic energy and ϵ using 13 months of observations from a profiling lidar deployed on a platform off the Massachusetts coast. Offshore, ϵ is 2 orders of magnitude smaller than onshore, with a subtle diurnal cycle. Wind direction influences the annual cycle of turbulence, with larger values in winter when the wind flows from the land, and smaller values in summer, when the wind flows from open ocean. Because of the weak turbulence, wind plant wakes will be stronger and persist farther downwind in summer.Collection of the wind data was funded by the Massachusetts Clean Energy Center through agreements with WHOI and AWS Truepower. The authors appreciate the efforts of the MVCO/ASIT technicians and AWS staff who collected the data. This analysis was supported by the National Science Foundation CAREER Award (AGS‐1554055) to J. K. L. and N. B., and by internal funds from WHOI for A. K. This work was authored (in part) by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract DE‐AC36‐08GO28308. Funding was provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid‐up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. The lidar observations used here are described at https://www.masscec.com/masscec-metocean-data-initiative, and available at https://doi.org/10.26025/1912/24050. The postprocessed data and the scripts used for the Figures of the present paper can be found at https://github.com/nicolabodini/GRL_OffshoreTurbulence.2019-11-0

    Individualized Breakfast Programs or Glycogen Super-Compensation: Which Is the Better Performing Strategy? Insights from an Italian Soccer Referees Cohort

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    The role of soccer referees has grown in importance in the last decades, as has attention to their performance, which may be influenced and improved with specific and evolved training programs. Today, multiple specialists are working as a team in order to develop effective training programs. Moreover, for athletes, it is becoming more and more important to be attentive to nutrition. By considering such items, in this study, we aimed to investigate the nutritional habits of a group of referees belonging to the Italian Soccer Referees' Association (on behalf of AIA-FIGC). Our main aim was to spread a "culture of nutrition" in refereeing, starting with a survey on referees' breakfast attitudes and in order to disseminate such a "culture", we chose top-level elite referees who were younger subjects (despite the average 4 years' experience). Therefore, we enrolled 31 subjects (aged 22.74 \ub1 1.79, BMI 22.30 \ub1 1.53) and asked them about their breakfast habits. Then, for measuring their performance, we used the conventional fitness test named Yo-Yo (YYiR1), performed in three different sessions (test 1, test 2, test 3). Test 1 was carried out without any nutritional indications, test 2 was given after individualized breakfast suggestions by a designed dietician, and test 3 after an individualized glycogen super-compensation strategy. The Wilcoxon statistical analysis indicates that following an individualized breakfast strategy may enhance referees' performance (p < 0.0001), whereas no significant effects were observed with the glycogen super-compensation option. However, further studies will be necessary to better address this topic and clarify whether high-carbohydrates (high-CHO) intake may be useful in other sports

    Distances on Lozenge Tilings

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    International audienceIn this paper, a structural property of the set of lozenge tilings of a 2n-gon is highlighted. We introduce a simple combinatorial value called Hamming-distance, which is a lower bound for the flipdistance (i.e. the number of necessary local transformations involving three lozenges) between two given tilings. It is here proven that, for n5, We show that there is some deficient pairs of tilings for which the flip connection needs more flips than the combinatorial lower bound indicates

    The ESO Key-Programme ``A Homogeneous Bright QSO Survey'' - I The Methods and the ``Deep'' Fields

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    This is the first paper in a series aimed at defining a statistically significant sample of QSOs in the range 15<B<18.75 15 < B < 18.75 and 0.3<z<2.2 0.3 < z < 2.2. The selection is carried out using direct plates obtained at the ESO and UK Schmidt Telescopes, scanned with the COSMOS facility and searched for objects with an ultraviolet excess. Follow-up spectroscopy, carried out at ESO La Silla, is used to classify each candidate. In this initial paper, we describe the scientific objectives of the survey; the selection and observing techniques used. We present the first sample of 285 QSOs (MB<23M_B < -23) in a 153 deg2^2 area, covered by the six ``deep'' fields, intended to obtain significant statistics down B18.75B \simeq 18.75 with unprecedented photometric accuracy. From this database, QSO counts are determined in the magnitude range 17<B<18.75 17 < B < 18.75.Comment: 21 pages uuencoded compressed postscript, to appear in Astronomy and Astrophysics Supplements, 199

    Flunisolide Decreases Exhaled Nitric Oxide and Nitrotyrosine Levels in Asthmatic Children

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    Background. Exhaled nitric oxide (FeNO) has been reported to be elevated in the oxidative stress involved in asthmatic patients, and the reaction of nitric oxide (NO) with superoxide anions results in the formation of nitrotyrosine. The purpose of this study was to investigate the effect of inhaled steroid treatment on nitrotyrosine levels collected by exhaled breath condensate (EBC) and on FeNO. Methods. This was a single-blind placebo-controlled study. The lung function, FeNO, and nitrotyrosine levels were evaluated in 10 asthmatic children. Results. The nitrotyrosine levels were stable during the placebo period (T0 = 1.16 ng/ml versus T1 = 1.05 ng/ml; NS.), whereas they decreased after the treatment with flunisolide (T2 = 1.14 ng/ml versus T3 = 0.88 ng/ml; P < .001). No significant reduction in FeNO levels was observed after placebo treatment (T0 = 38.4 ppb versus T1 = 34.7 ppb, NS.). In contrast, FeNO values decreased significantly being at T3 = 14.9 ppb (T1 versus T3; P = .024). Conclusions. This study shows that corticosteroid treatment reduces nitrotyrosine levels in EBC of asthmatic subjects

    HLA-DRB1*15 influences the development of brain tissue damage in early PPMS

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    OBJECTIVES To investigate whether (1) there were differences between HLA-DRB1*15-positive and -negative patients at baseline, and (2) HLA-DRB1*15-positive patients showed a greater development of brain and spinal cord damage, as assessed by MRI, and greater progression of disability, during a 5-year follow-up, compared with HLA-DRB1*15-negative patients. METHODS HLA-DRB1*15 typing was performed in 41 patients with primary progressive multiple sclerosis (PPMS) who were recruited within 5 years of symptom onset. All patients and 18 healthy controls were studied clinically and with MRI at baseline, and every 6 months for 3 years, and then at 5 years. Magnetization transfer ratio parameters and volumes for brain gray matter and normal-appearing white matter, brain T2 lesion load, and spinal cord cross-sectional area were obtained. Patient disability was assessed at each visit using the Expanded Disability Status Scale and Multiple Sclerosis Functional Composite subscores. RESULTS There were no significant differences between HLA-DRB1*15-positive and -negative patients at baseline. HLA-DRB1*15-positive patients showed a greater decline in brain magnetization transfer ratio for gray matter and normal-appearing white matter (both p = 0.005) than HLA-DRB1*15-negative patients over 5 years, while the same parameters did not change over time in healthy controls. HLA-DRB1*15-positive patients also showed a trend toward a faster increase in brain T2 lesion load than HLA-DRB1*15-negative patients (0.29 [95% confidence interval 0.20-0.38] vs 0.21 [0.13-0.30] mL/mo, p = 0.085) and higher T2 lesion volumes at all time points (average difference [95% confidence interval]: 10.58 mL [7.09-14.07], p < 0.001) during the follow-up, after adjusting for disease duration. CONCLUSIONS These findings suggest that HLA-DRB1*15 influences the progression of brain pathology in PPMS

    Near-Threshold Production of omega Mesons in the pp -> pp omega Reaction

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    The total cross section for omega production in the pp -> pp omega reaction has been measured at five c.m. excess energies from 3.8 to 30 MeV. The energy dependence is easily understood in terms of a strong proton-proton final state interaction combined with a smearing over the width of the state. The ratio of near-threshold phi and omega production is consistent with the predictions of a one-pion-exchange model and the degree of violation of the OZI rule is similar to that found in the pi-p -> n omega/phi reactions.Comment: Report in LaTeX2e. 12 pages with 2 eps figure
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