569 research outputs found

    Effect of configuration variation on externally blown flap noise

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    The sensitivity of flap interaction noise to variations in engine-under-the-wing externally blown flap geometry was investigated with a large cold-flow model. Both 2- and 3-flap wing sections (7-ft chord) with trailing flap angles up to 60 deg were employed. Exhaust nozzles included coaxial, plug, and 8- and 13-inch diameter conical configurations. These nozzles were tested at two positions below the wing. The effects of these geometry variations on noise level, directivity, and spectral shape are summarized in terms of exhaust flow parameters evaluated at the nozzle exit and at the flap impingement station. The results are also compared with limited flap noise data available from tests using real engines

    Maximally Localized States in Quantum Mechanics with a Modified Commutation Relation to All Orders

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    We construct the states of maximal localization taking into account a modification of the commutation relation between position and momentum operators to all orders of the minimum length parameter. To first order, the algebra we use reproduces the one proposed by Kempft, Mangano and Mann. It is emphasized that a minimal length acts as a natural regulator for the theory, thus eliminating the otherwise ever appearing infinities. So, we use our results to calculate the first correction to the Casimir Effect due to the minimal length. We also discuss some of the physical consequences of the existence of a minimal length, culminating in a proposal to reformulate the very concept of "position measurement"

    Novel potential interacting partners of fibronectin in spontaneous animal model of interstitial cystitis

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    Feline idiopathic cystitis (FIC) is the only spontaneous animal model for human interstitial cystitis (IC), as both possess a distinctive chronical and relapsing character. Underlying pathomechanisms of both diseases are not clearly established yet. We recently detected increased urine fibronectin levels in FIC cases. The purpose of this study was to gain further insight into the pathogenesis by assessing interacting partners of fibronectin in urine of FIC affected cats. Several candidate proteins were identified via immunoprecipitation and mass spectrometry. Considerable changes in FIC conditions compared to physiological expression of co-purified proteins were detected by Western blot and immunohistochemistry. Compared to controls, complement C4a and thioredoxin were present in higher levels in urine of FIC patients whereas loss of signal intensity was detected in FIC affected tissue. Galectin-7 was exclusively detected in urine of FIC cats, pointing to an important role of this molecule in FIC pathogenesis. Moderate physiological signal intensity of galectin-7 in transitional epithelium shifted to distinct expression in transitional epithelium under pathophysiological conditions. I-FABP expression was reduced in urine and urinary bladder tissue of FIC cats. Additionally, transduction molecules of thioredoxin, NF-ÎșB p65 and p38 MAPK, were examined. In FIC affected tissue, colocalization of thioredoxin and NF-ÎșB p65 could be demonstrated compared to absent coexpression of thioredoxin and p38 MAPK. These considerable changes in expression level and pattern point to an important role for co-purified proteins of fibronectin and thioredoxin-regulated signal transduction pathways in FIC pathogenesis. These results could provide a promising starting point for novel therapeutic approaches in the future

    Exploring the Impact of Coaches’ Emotional Abuse on Intercollegiate Student-Athletes’ Experiences

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    Despite widespread anecdotal accounts of coaches’ emotional abuse in intercollegiate sports, empirical literature is lacking. To address this gap, the present exploratory study was designed to explore how former intercollegiate student-athletes interpreted experiences of emotionally abusive coaching. Former female NCAA and NJCAA student-athletes (N = 14; Mage = 25.3 years) took part in semi-structured, in-depth interviews. Data were interpreted using a constructivist grounded theory approach. The final product of the research was a three-stage grounded theory explaining how former student-athletes interpret their experiences of emotional abuse over time organized into sections on antecedents to abuse, experiences and actions within the abusive program, and after the abuse. Implications for this work include the idea that individual student-athletes may have different experiences and recollections of coaches’ emotionally abusive behavior and that intercollegiate student-athletes are able to discern between “hard, but fair” coaching practices and emotionally abusive coaching practices

    Parental Involvement Among Collegiate Student-Athletes: An Analysis Across NCAA Divisions

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    Despite emerging evidence of a link between parental involvement and student-athletes’ (SA) experiences, and the desire for educational programming for parents of these SAs, previous research has been limited to the Division I level. This has prevented the ability to inform, develop, and deliver parent programming across the NCAA’s diverse membership. The present study was designed to descriptively assess SA reports of parental involvement (i.e., support, contact, academic engagement, athletic engagement) across NCAA Division I, II, and III member institutions and examine the potential impact of this involvement on SAs’ experiences (i.e., academic self-efficacy, athletic satisfaction, well-being, individuation). Participants were 455 SAs (53% female; 81% Caucasian; Mage = 19.81, SD = 1.65) from DI (30%), DII (37%), and DIII (33%) institutions, who completed an online survey with items assessing parental involvement and SA experiences. Regarding academic classification, 32% were freshmen, 24% sophomores, 22% juniors, and 22% seniors. Results provide novel evidence for an absence of division-wide differences in average levels of involvement and no variability in links between involvement and SA experiences across divisions. Results complement and extend previous research by offering a clearer understanding of differential associations between involvement and SAs’ experiences regardless of division, notably that involvement bolstered well-being but also strongly detracted from individuation. Findings highlight the importance of developing programs to promote positive and developmentally-appropriate parental involvement across the spectrum of intercollegiate athletics, especially given the absence of evidence-based resources presently offered by the NCAA

    The Higgs vacuum uplifted: revisiting the electroweak phase transition with a second Higgs doublet

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    The existence of a second Higgs doublet in Nature could lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We explore the parameter space of such a two-Higgs-doublet-model and show that a first order electroweak phase transition strongly correlates with a significant uplifting of the Higgs vacuum w.r.t. its Standard Model value. We then obtain the spectrum and properties of the new scalars H0, A0 and H± that signal such a phase transition, showing that the decay A0 → H0Z at the LHC and a sizable deviation in the Higgs self-coupling λhhh from its SM value are sensitive indicators of a strongly first order electroweak phase transition in the 2HDM

    How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review

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    Background Teaching of evidence-based medicine (EBM) has become widespread in medical education. Teaching the teachers (TTT) courses address the increased teaching demand and the need to improve effectiveness of EBM teaching. We conducted a systematic review of assessment tools for EBM TTT courses. To summarise and appraise existing assessment methods for teaching the teachers courses in EBM by a systematic review. Methods We searched PubMed, BioMed, EmBase, Cochrane and Eric databases without language restrictions and included articles that assessed its participants. Study selection and data extraction were conducted independently by two reviewers. Results Of 1230 potentially relevant studies, five papers met the selection criteria. There were no specific assessment tools for evaluating effectiveness of EBM TTT courses. Some of the material available might be useful in initiating the development of such an assessment tool. Conclusion There is a need for the development of educationally sound assessment tools for teaching the teachers courses in EBM, without which it would be impossible to ascertain if such courses have the desired effect

    Challenges in measuring nitrogen isotope signatures in inorganic nitrogen forms: An interlaboratory comparison of three common measurement approaches

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    Rationale Stable isotope approaches are increasingly applied to better understand the cycling of inorganic nitrogen (Ni) forms, key limiting nutrients in terrestrial and aquatic ecosystems. A systematic comparison of the accuracy and precision of the most commonly used methods to analyze ÎŽ15N in NO3− and NH4+ and interlaboratory comparison tests to evaluate the comparability of isotope results between laboratories are, however, still lacking. Methods Here, we conducted an interlaboratory comparison involving 10 European laboratories to compare different methods and laboratory performance to measure ÎŽ15N in NO3− and NH4+. The approaches tested were (a) microdiffusion (MD), (b) chemical conversion (CM), which transforms Ni to either N2O (CM-N2O) or N2 (CM-N2), and (c) the denitrifier (DN) methods. Results The study showed that standards in their single forms were reasonably replicated by the different methods and laboratories, with laboratories applying CM-N2O performing superior for both NO3− and NH4+, followed by DN. Laboratories using MD significantly underestimated the “true” values due to incomplete recovery and also those using CM-N2 showed issues with isotope fractionation. Most methods and laboratories underestimated the at%15N of Ni of labeled standards in their single forms, but relative errors were within maximal 6% deviation from the real value and therefore acceptable. The results showed further that MD is strongly biased by nonspecificity. The results of the environmental samples were generally highly variable, with standard deviations (SD) of up to ± 8.4‰ for NO3− and ± 32.9‰ for NH4+; SDs within laboratories were found to be considerably lower (on average 3.1‰). The variability could not be connected to any single factor but next to errors due to blank contamination, isotope normalization, and fractionation, and also matrix effects and analytical errors have to be considered
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