268 research outputs found

    Effect of Moment Gradient and Load Height With Respect to Centroid on the Reliability of Wide Flange Steel Beams Subject to Elastic Lateral Torsional Buckling

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    The reliability of doubly-symmetric wide flange steel beams designed to the AISC Specification for Structural Steel Buildings subjected to elastic lateral torsional buckling was evaluated when considering variation in moment gradient and load height. The analysis considers continuous loads on spans subjected to various end moments with supports that are torsionally fixed and laterally supported, without additional intermediate restraints. Dead load, occupancy live load, and beam resistance random variables were considered. Beam lateral torsional buckling resistance was evaluated from numerical solution of a fundamental differential equation that accounts for the effect of moment gradient and load height. In some cases, it was found that use of the AISC design procedure results in significant inaccuracies for estimation of elastic lateral torsional buckling resistance, where underestimations occur in regions of reverse curvature bending and when loads are placed below the beam shear center, while large overestimations can occur when loads are placed above the beam shear center. These discrepancies result in significant variation in beam reliability. However, the use of accurate equivalent uniform moment factors can restore uniformity in notional reliability level

    Recent Transits of the Super-Earth Exoplanet GJ 1214b

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    We report recent ground-based photometry of the transiting super-Earth exoplanet GJ1214b at several wavelengths, including the infrared near 1.25 microns (J-band). We observed a J-band transit with the FLAMINGOS infrared imager and the 2.1-meter telescope on Kitt Peak, and we observed several optical transits using a 0.5-meter telescope on Kitt Peak and the 0.36-meter Universidad de Monterrey Observatory telescope. Our high-precision J-band observations exploit the brightness of the M-dwarf host star at this infrared wavelength as compared to the optical, as well as being significantly less affected by stellar activity and limb darkening. We fit the J-band transit to obtain an independent determination of the planetary and stellar radii. Our radius for the planet (2.61^+0.30_-0.11 Earth radii) is in excellent agreement with the discovery value reported by Charbonneau et al. based on optical data. We demonstrate that the planetary radius is insensitive to degeneracies in the fitting process. We use all of our observations to improve the transit ephemeris, finding P=1.5804043 +/- 0.0000005 days, and T0=2454964.94390 +/- 0.00006 BJD.Comment: Accepted for ApJ Letters, 7 pages, 3 Figures, 2 Table

    Extrasolar Planet Transits Observed at Kitt Peak National Observatory

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    We obtained J-, H- and JH-band photometry of known extrasolar planet transiting systems at the 2.1-m Kitt Peak National Observatory Telescope using the FLAMINGOS infrared camera between October 2008 and October 2011. From the derived lightcurves we have extracted the mid-transit times, transit depths and transit durations for these events. The precise mid-transit times obtained help improve the orbital periods and also constrain transit-time variations of the systems. For most cases the published system parameters successfully accounted for our observed lightcurves, but in some instances we derive improved planetary radii and orbital periods. We complemented our 2.1-m infrared observations using CCD z'-band and B-band photometry (plus two Hydrogen Alpha filter observations) obtained with the Kitt Peak Visitor's Center telescope, and with four H-band transits observed in October 2007 with the NSO's 1.6-m McMath-Pierce Solar Telescope. The principal highlights of our results are: 1) our ensemble of J-band planetary radii agree with optical radii, with the best-fit relation being: (Rp/R*)J = 0.0017 + 0.979 (Rp/R*)optical, 2) We observe star spot crossings during the transit of WASP-11/HAT-P-10, 3) we detect star spot crossings by HAT-P-11b (Kepler-3b), thus confirming that the magnetic evolution of the stellar active regions can be monitored even after the Kepler mission has ended, and 4) we confirm a grazing transit for HAT-P-27/WASP-40. In total we present 57 individual transits of 32 known exoplanet systems.Comment: 33 pages, 6 figures, accepted in Publications of the Astronomical Society of the Pacifi

    Prevalence of treatment-resistant hypertension after considering pseudo-resistance and morbidity: a cross-sectional study in Irish primary care

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    peer-reviewedBackground To confirm treatment-resistant hypertension (TRH), ambulatory blood pressure measurement (ABPM) must exclude white-coat hypertension (WCH), three or more medications should be prescribed at the optimal doses tolerated, and non-adherence and lifestyle should be examined. Most previous studies have not adequately considered pseudo-resistance and merely provide an apparent TRH (aTRH) prevalence figure. Aim To conduct a cross-sectional study of the prevalence of aTRH in general practice, and then consider pseudo-resistance and morbidity. Design and setting With support, 16 practices ran an anatomical therapeutic chemical (ATC) drug search, identifying patients on any possible hypertensive medications, and then a search of individual patients' electronic records took place. Method ABPM was used to rule out WCH. The World Health Organization-defined daily dosing guidelines determined adequate dosing. Adherence was defined as whether patients requested nine or more repeat monthly prescriptions within the past year. Results Sixteen practices participated (n = 50 172), and 646 patients had aTRH. Dosing was adequate in 19% of patients, 84% were adherent to medications, as defined by prescription refill, and 43% had ever had an ABPM. Using a BP cut-off of 140/90 mmHg, the prevalence of aTRH was 9% (95% confidence interval [CI] = 9.0 to 10.0). Consideration of pseudo-resistance further reduced prevalence rates to 3% (95% CI = 3.0 to 4.0). Conclusion Reviewing individual patient records results in a lower estimate of prevalence of TRH than has been previously reported. Further consideration for individual patients of pseudo-resistance additionally lowers these estimates, and may be all that is required for management in the vast majority of cases.PUBLISHEDpeer-reviewe

    Lack of genetic structure and evidence for long-distance dispersal in ash (Fraxinus excelsior) populations under threat from an emergent fungal pathogen:Implications for restorative planting

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    Genetic analysis on populations of European ash (Fraxinus excelsior) throughout Ireland was carried out to determine the levels and patterns of genetic diversity in naturally seeded trees in ash woodlands and hedgerows, with the aim of informing conservation and replanting strategies in the face of potential loss of trees as a result of ash dieback. Samples from 33 sites across Northern Ireland and three sites in the Republic of Ireland were genotyped for eight nuclear and ten chloroplast microsatellites. Levels of diversity were (h)igh (mean A(R)=10.53; mean H-O=0.709; mean H-E=0.765) and were similar to those in Great Britain and continental Europe, whilst levels of population genetic differentiation based on nuclear microsatellites were extremely low ((Phi) over bar (ST)=0.0131). Levels of inbreeding (mean F-IS=0.067) were significantly lower than those reported for populations from Great Britain. Fine-scale analysis of seed dispersal indicated potential for dispersal over hundreds of metres. Our results suggest that ash woodlands across Ireland could be treated as a single management unit, and thus native material from anywhere in Ireland could be used as a source for replanting. In addition, high potential for dispersal has implications for recolonization processes post-ash dieback (Chalara fraxinea) infection, and could aid in our assessment of the capacity of ash to shift its range in response to global climate change.authorsversionPeer reviewe

    Scientific Academies

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    The first Renaissance academies developed around the middle of the fifteenth century and had a primarily encyclopedic character. The main trait of the knowledge cultivated in their first phase was the revival of the classical culture. On the one hand they, fostered a renewed interest especially in Platonic philosophy, and on the other hand they cultivated the dream of a somewhat all-embracing knowledge. Vernacular literature, liberal arts, music, mathematics, and the study of nature were all parts, within the fifteenth to sixteenth-century academies, of a wider landscape of interests. It is exactly this tension and strife towards a unifying and organic picture of knowledge that threatens any attempt at formulating a classification of themes and contents that were addresses by the first renaissance academies. The question of the scientific academy in the Renaissance should thus be posed and defined considering on the one hand the relation with the wider academic phenomenology and on the other hand with the birth and rise of the \u201cnew science,\u201d in particular when it comes to the very process that science underwent in order to be autonomous from an organic and homogeneous view of knowledge, a view that was exactly the hallmark of that model in which the academies were born

    Developing a typology for peer education and peer support delivered by prisoners

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    Peer interventions delivered for prisoners by prisoners offer a means to improve health and reduce risk factors for this population. The variety of peer programs poses challenges for synthesizing evidence. This paper presents a typology developed as part of a systematic review of peer interventions in prison settings. Peer interventions are grouped into four modes: peer education, peer support, peer mentoring and bridging roles, with the addition of a number of specific interventions identified through the review process. The paper discusses the different modes of peer delivery with reference to a wider health promotion literature on the value of social influence and support. In conclusion, the typology offers a framework for developing the evidence base across a diverse field of practice in correctional health care

    Prevalence of problem alcohol use among patients attending primary care for methadone treatment

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    <p>Abstract</p> <p>Background</p> <p>Problem alcohol use is associated with adverse health outcomes among current or former heroin users and primary care is providing methadone treatment for increasing numbers of this population. This study aimed todetermine the prevalence of problem alcohol use among current or former heroin users attending primary care for methadone treatment and to describe the socio-demographic characteristics and health service utilisation characteristics associated with problem alcohol uses.</p> <p>Methods</p> <p>We conducted a cross sectional survey of patients sampled from a national database of patients attending general practice for methadone treatment. Participants were recruited by their general practitioner and data was collected using an interviewer-administered questionnaire, which included the Alcohol Use Disorders Identification Test ('AUDIT'), with a score of >7 considered abnormal (ie 'AUDIT positive cases') and socio-demographic, medical and substance use characteristics.</p> <p>Results</p> <p>We interviewed 196 patients (71% of those invited, 31% of those sampled, 11% of the national database). The median age was 32 years, 55% were hepatitis C positive, 79% had used illicit drugs in the previous month and 68% were male. Sixty-eight 'AUDIT positive' cases were identified (prevalence of 35%, 95% CI = 28–41%) and these were more likely to have attended a local Emergency Department in the previous year (p < 0.05) and less likely to have attended a hospital clinic in the previous year (p < 0.05). Twenty-seven (14%) scored 20 or higher indicating possible alcohol dependence.</p> <p>Conclusion</p> <p>Problem alcohol use has a high prevalence among current or former heroin users attending primary care for methadone treatment and interventions that address this issue should be explored as a priority. Interventions that address problem alcohol use in this population should be considered as a priority, although the complex medical and psychological needs of this population may make this challenging.</p

    A systematic review of the effectiveness and cost-effectiveness of peer education and peer support in prisons.

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    BACKGROUND: Prisoners experience significantly worse health than the general population. This review examines the effectiveness and cost-effectiveness of peer interventions in prison settings. METHODS: A mixed methods systematic review of effectiveness and cost-effectiveness studies, including qualitative and quantitative synthesis was conducted. In addition to grey literature identified and searches of websites, nineteen electronic databases were searched from 1985 to 2012. Study selection criteria were: Population: Prisoners resident in adult prisons and children resident in Young Offender Institutions (YOIs). INTERVENTION: Peer-based interventions Comparators: Review questions 3 and 4 compared peer and professionally led approaches. OUTCOMES: Prisoner health or determinants of health; organisational/ process outcomes; views of prison populations. STUDY DESIGNS: Quantitative, qualitative and mixed method evaluations. RESULTS: Fifty-seven studies were included in the effectiveness review and one study in the cost-effectiveness review; most were of poor methodological quality. Evidence suggested that peer education interventions are effective at reducing risky behaviours, and that peer support services are acceptable within the prison environment and have a positive effect on recipients, practically or emotionally. Consistent evidence from many, predominantly qualitative, studies, suggested that being a peer deliverer was associated with positive effects. There was little evidence on cost-effectiveness of peer-based interventions. CONCLUSIONS: There is consistent evidence from a large number of studies that being a peer worker is associated with positive health; peer support services are also an acceptable source of help within the prison environment and can have a positive effect on recipients. Research into cost-effectiveness is sparse. SYSTEMATIC REVIEW REGISTRATION: PROSPERO ref: CRD42012002349

    The differential effects of concurrent planning practice elements on reunification and adoption

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    Objective: The child welfare practice of concurrent planning attempts to shorten children\u27s stays in foster care. There is very little quantitative research on concurrent planning\u27s effects. This study examines the influence of concurrent planning practice elements (reunification prognosis, concurrent plan, full disclosure, and discussion of voluntary relinquishment) on reunification and adoption. Method: Using a sample of 885 children, an observational design, and statistical controls, children who received concurrent planning elements were compared to those who did not. Results: Findings show discussion of voluntary relinquishment to be positively associated with adoption and full disclosure to be negatively associated with reunification. Conclusions: Concurrent planning\u27s benefits may require more intensive services to be fully realized. Care should be taken to ensure activities achieve their intended effects
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