1,474 research outputs found

    Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 2: Data analysis

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    Assessing the performance of a MOD-OA horizontal axis wind turbine connected to an isolated diesel utility, a comprehensive data measurement program was conducted on the Block Island Power Company installation on Block Island, Rhode Island. The detailed results of that program focusing on three principal areas of (1) fuel displacement (savings), (2) dynamic interaction between the diesel utility and the wind turbine, (3) effects of three models of wind turbine reactive power control are presented. The approximate two month duration of the data acquisition program conducted in the winter months (February into April 1982) revealed performance during periods of highest wind energy penetration and hence severity of operation. Even under such conditions fuel savings were significant resulting in a fuel reduction of 6.7% while the MOD-OA was generating 10.7% of the total electrical energy. Also, electrical disturbance and interactive effects were of an acceptable level

    Unconventional Magnetization below 25 K in Nitrogen-doped Diamond provides hints for the existence of Superconductivity and Superparamagnetism

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    The magnetization of nitrogen-doped single crystalline diamond bulk samples shows unconventional field and temperature hysteresis loops at T ≲ 25 K. The results suggest the existence of superparamagnetic and superconducting regions in samples with nitrogen concentration <200 ppm. Both phases vanish at temperatures above 25 K where the samples show diamagnetic behavior similar to undoped diamond. The observation of superparamagnetism and superconductivity is attributed to the nitrogen doping and to the existence of defective regions. From particle-induced X-ray emission with ppm resolution we rule out that the main observations below 25 K are due to magnetic impurities. We investigated also the magnetic properties of ferromagnetic/high-temperature superconducting oxide bilayers. The magnetization results obtained from those bilayers show remarkable similarities to the ones in nitrogen-doped diamond

    Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1: Executive summary

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    Primary results are summarized for a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The MOD-OA installation considered was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program and was characterized by the highest wind energy penetration levels of four sites. The study analyses address: fuel displacement, dynamic interaction, and three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted on Block Island, Rhode Island

    Resolution and Efficiency of the ATLAS Muon Drift-Tube Chambers at High Background Rates

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    The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100 GeV muon beam and at photon irradiation rates of up to 990 Hz/square cm which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope was used as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections which lead to an improvement of the average drift-tube resolution from 104 microns to 82 microns without irradiation and from 128 microns to 108 microns at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate

    Patterns of care and survival for patients aged under 40 years with bone sarcoma in Britain, 1980–1994

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    The purpose of the study was to calculate population-based survival rates for osteosarcoma (OS) and Ewing's sarcoma (ES) in Great Britain during 1980–1994, determine proportions of patients treated at specialist centres or entered in national and international clinical trials, and investigate effects of these factors on survival. Data on a population-based series of 1349 patients with OS and 849 with ES were compiled from regional and national cancer registries, UK Children's Cancer Study Group, regional bone tumour registries and clinical trials. Follow-up was through population registers. Survival was analysed by actuarial analysis with log-rank tests and by Cox's proportional hazards analysis. Five-year survival rates during 1980–1984, 1985–1989 and 1990–1994 were 42% (95% CI: 37, 46), 54% (95% CI: 50, 59) and 53% (95% CI: 48, 57), respectively, for OS and 31% (95% CI: 26, 37), 46% (95% CI: 40, 51) and 51% (95% CI: 45, 57) for ES. Proportions of patients treated at a supraregional bone tumour centre or a paediatric oncology centre in the three quinquennia were 36, 56 and 67% for OS and 41, 60 and 69% for ES. In 1983–1992, 48% of OS patients were entered in a national trial; for ES, 27% were entered in 1980–1986 and 54% in 1987–1994. Survival was similar for trial and nontrial patients with OS. For ES, trial patients had consistently higher 5-year survival than nontrial patients: 1980–1986, 42 vs 30%; 1987–1992, 59 vs 42%; 1993–1994, 54 vs 43%. During 1985–1994, patients with OS or ES whose main treatment centre was a nonteaching hospital had lower survival rates. In multivariate analyses of patients diagnosed during 1985–1994 that also included age, sex, primary site, surgical treatment centre, the results relating to main treatment centre for both OS and ES retained significance but the survival advantage of trial entry for ES became nonsignificant. For both OS and ES diagnosed since 1985, patients whose main treatment centre was a nonspecialist hospital had a lower survival rate

    A Cosmic Ray Measurement Facility for ATLAS Muon Chambers

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    Monitored Drift Tube (MDT) chambers will constitute the large majority of precision detectors in the Muon Spectrometer of the ATLAS experiment at the Large Hadron Collider at CERN. For commissioning and calibration of MDT chambers, a Cosmic Ray Measurement Facility is in operation at Munich University. The objectives of this facility are to test the chambers and on-chamber electronics, to map the positions of the anode wires within the chambers with the precision needed for standalone muon momentum measurement in ATLAS, and to gain experience in the operation of the chambers and on-line calibration procedures. Until the start of muon chamber installation in ATLAS, 88 chambers built at the Max Planck Institute for Physics in Munich have to be commissioned and calibrated. With a data taking period of one day individual wire positions can be measured with an accuracy of 8.3 micrometers in the chamber plane and 27 micrometers in the direction perpendicular to that plane.Comment: 14+1 pages, 11 figures, contributed paper to the EPS2003 conference, Aache

    Nonintrinsic origin of the magnetic-field-induced metal-insulator and electronic phase transitions in graphite

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    A detailed magnetoresistance study of bulk and microflake samples of highly oriented pyrolytic graphite with a thickness of 25 ÎĽm to 23~nm reveals that the usually observed field-induced metal-insulator and electronic phase transitions vanish in thinner samples. The observed suppression is accompanied by orders of magnitude decrease of the magnetoresistance and of the amplitude of the Shubnikov-de-Haas oscillations. The overall behavior is related to the decrease in the quantity of two-dimensional interfaces between crystalline regions of the same and different stacking orders present in graphite samples. Our results indicate that these field-induced transitions are not intrinsic to the ideal graphite structure and, therefore, a relevant portion of the published interpretations should be reconsidered

    The HealtheSteps™ lifestyle prescription program to improve physical activity and modifiable risk factors for chronic disease: a pragmatic randomized controlled trial.

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    BACKGROUND: Our objective was to determine the influence of the HealtheSteps™ lifestyle prescription program on physical activity and modifiable risk factors for chronic disease in individuals at risk. METHODS: One hundred eighteen participants were recruited from 5 sites in Southwestern Ontario, Canada and randomized to either the intervention (HealtheSteps™ program, n = 59) or a wait-list control group (n = 59). The study comprised three phases: an Active Phase (0 to 6 months) consisted of bi-monthly in-person lifestyle coaching with access to a suite of eHealth technology supports (Heathesteps app, telephone coaching and a private HealtheSteps™ social network) followed by a Minimally-Supported Phase I (6 to 12 months), in which in-person coaching was removed, but participants still had access to the full suite of eHealth technology supports. In the final stage, Minimally-Supported Phase II (12 to 18 months), access to the eHealth technology supports was restricted to the HealtheSteps™ app. Assessments were conducted at baseline, 6, 12 and 18 months. The study primary outcome was the 6-month change in average number of steps per day. Secondary outcomes included: self-reported physical activity and sedentary time; self-reported eating habits; weight and body composition measures; blood pressure and health-related quality of life. Data from all participants were analyzed using an intent-to-treat approach. We applied mixed effects models for repeated measurements and adjusted for age, sex, and site in the statistical analyses. RESULTS: Participants in HealtheSteps™ increased step counts (between-group [95% confidence interval]: 3132 [1969 to 4294], p \u3c 0.001), decreased their sitting time (- 0.08 [- 0.16 to - 0.006], p = 0.03), and improved their overall healthful eating (- 1.5 [- 2.42 to - 0.58], p = 0.002) to a greater extent compared to control at 6 months. Furthermore, exploratory results showed that these individuals maintained these outcomes 12 months later, after a minimally-supported phase; and retained improvements in sedentary time and improved healthful eating after 18 months. No differences in self-reported physical activity, health-related quality of life, weight, waist circumference or blood pressure were observed between groups at 6 months. CONCLUSIONS: Our findings suggest that HealtheSteps™ is effective at increasing physical activity (i.e., step counts per day), decreasing weekday sitting time, and improving healthful eating in adults at increased risk for chronic disease after 6 months; however, we did not see change in other risk factors. Nonetheless, the maintenance of these behaviours with minimal support after 12 and even 18 months indicates the promise of HealtheSteps™ for long-term sustainability. TRIAL REGISTRATION: The trial was registered on April 6, 2015 with ClinicalTrials.gov (identifier: NCT02413385 )

    Incidence and survival of childhood bone cancer in northern England and the West Midlands, 1981–2002

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    There is a paucity of population-based studies examining incidence and survival trends in childhood bone tumours. We used high quality data from four population-based registries in England. Incidence patterns and trends were described using Poisson regression. Survival trends were analysed using Cox regression. There were 374 cases of childhood (ages 0–14 years) bone tumours (206 osteosarcomas, 144 Ewing sarcomas, 16 chondrosarcomas, 8 other bone tumours) registered in the period 1981–2002. Overall incidence (per million person years) rates were 2.63 (95% confidence interval (CI) 2.27–2.99) for osteosarcoma, 1.90 (1.58–2.21) for Ewing sarcoma and 0.21 (0.11–0.31) for chondrosarcoma. Incidence of Ewing sarcoma declined at an average rate of 3.1% (95% CI 0.6–5.6) per annum (P=0.04), which may be due to tumour reclassification, but there was no change in osteosarcoma incidence. Survival showed marked improvement over the 20 years (1981–2000) for Ewing sarcoma (hazard ratio (HR) per annum=0.95 95% CI 0.91–0.99; P=0.02). However, no improvement was seen for osteosarcoma patients (HR per annum=1.02 95% CI 0.98–1.05; P=0.35) over this time period. Reasons for failure to improve survival including potential delays in diagnosis, accrual to trials, adherence to therapy and lack of improvement in treatment strategies all need to be considered

    Seasonal Changes in Sleep Duration in African American and African College Students Living In Washington, D.C.

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    Duration of nocturnal melatonin secretion, a marker of “biological night” that relates to sleep duration, is longer in winter than in summer in patients with seasonal affective disorder (SAD), but not in healthy controls. In this study of African and African American college students, we hypothesized that students who met criteria for winter SAD or subsyndromal SAD (S-SAD) would report sleeping longer in winter than in summer. In addition, based on our previous observation that Africans report more “problems” with change in seasons than African Americans, we expected that the seasonal changes in sleep duration would be greater in African students than in African American students. Based on Seasonal Pattern Assessment Questionnaire (SPAQ) responses, African American and African college students in Washington, D.C. (N = 575) were grouped into a winter SAD/S-SAD group or a no winter diagnosis group, and winter and summer sleep length were determined. We conducted a 2 (season) × 2 (sex) × 2 (ethnicity) × 2 (winter diagnosis group) ANCOVA on reported sleep duration, controlling for age. Contrary to our hypothesis, we found that African and African American students with winter SAD/S-SAD report sleeping longer in the summer than in the winter. No differences in seasonality of sleep were found between African and African American students. Students with winter SAD or S-SAD may need to sacrifice sleep duration in the winter, when their academic functioning/efficiency may be impaired by syndromal or subsyndromal depression, in order to meet seasonally increased academic demands
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