19,828 research outputs found

    Design evaluation criteria for commercial STOL transports

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    Handling qualities criteria and operational performance margins have been determined for the landing phase of commercial short-takeoff-and-landing airplanes. The requirements are the result of a literature survey, analysis of areas found to be inadequately covered by current criteria, and a subsequent piloted simulator investigation of critical criteria requiring substantiation. Three complete simulator models were used, each describing the characteristics of a different high-lift system, the externally blown flap, the augmentor flap, and the internally blown flap. The proposed criteria are presented with substantiating discussions from currently available data or directly from the results of this simulation work where it is applicable

    Real estate stock selection and attribute preferences

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    The majority of studies that explore property portfolio construction and management strategies utilise highly aggregated ex-post data, but stock selection is known to be a significant determinant of portfolio performance. Thus, here we look at stock selection, focusing on the choices faced by investors, necessitating the collection and analysis of primary data, carried out utilising conjoint analysis. This represents a new step in property research, with the data collection undertaken using a simulation exercise. This enables fund managers to make hypothetical purchase decisions, viewing properties comprising a realistic bundle of attributes and making complex contemporaneous trade-offs between attributes, subject to their stated market and economic forecasts and sector specialism. In total 51 fund managers were surveyed, producing 918 purchase decisions for analysis, with additional data collected regarding fund and personal characteristics. The results reveal that ‘fixed’ property characteristics (location and obsolescence) are dominant in the decision-making process, over and above ‘manageable’ tenant and lease characteristics which can be explicitly included within models of probabilities of income variation. This reveals investors are making ex-ante risk judgements and are considering post acquisition risk management strategies. The study also reveals that behavioural factors affect acquisition decisions

    Minimal Brownian Ratchet: An Exactly Solvable Model

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    We develop an exactly-solvable three-state discrete-time minimal Brownian ratchet (MBR), where the transition probabilities between states are asymmetric. By solving the master equations we obtain the steady-state probabilities. Generally the steady-state solution does not display detailed balance, giving rise to an induced directional motion in the MBR. For a reduced two-dimensional parameter space we find the null-curve on which the net current vanishes and detailed balance holds. A system on this curve is said to be balanced. On the null-curve, an additional source of external random noise is introduced to show that a directional motion can be induced under the zero overall driving force. We also indicate the off-balance behavior with biased random noise.Comment: 4 pages, 4 figures, RevTex source, General solution added. To be appeared in Phys. Rev. Let

    THE RELATIONSHIP BETWEEN MUSCULOSKELETAL STRENGTH, PHYSIOLOGICAL CHARACTERISTICS, AND KNEE KINESTHESIA FOLLOWING FATIGUING EXERCISE

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    Fatiguing exercise may result in impaired functional joint stability and increased risk of unintentional injury. While there are several musculoskeletal and physiological characteristics related to fatigue onset, their relationship with proprioceptive changes following fatigue has not been examined. The purpose of this study was to establish the relationship between musculoskeletal and physiological characteristics and changes in proprioception, measured by threshold to detect passive motion (TTDPM), following fatiguing exercise. Twenty, physically active females participated (age: 28.65 ± 5.6 years, height: 165.6 ± 4.3 cm, weight: 61.8 ± 8.0 kg, BMI: 22.5± 2.3 kg/m2, BF: 23.3 ± 5.4%). During Visit 1, subjects completed an exercise history and 24-hour dietary questionnaire, and body composition, TTDPM familiarization, isokinetic knee strength, and maximal oxygen uptake/lactate threshold assessments. During Visit 2, subjects completed TTDPM and isometric knee strength testing prior to and following a fatiguing exercise protocol. Wilcoxon signed rank tests determined TTDPM and isometric knee strength changes from pre- to post- fatigue. Spearman’s rho correlation coefficients determined the relationship between strength and physiological variables with pre- to post-fatigue changes in TTDPM and with pre-fatigue and post-fatigue TTDPM in extension and flexion (α=0.05). No significant differences were demonstrated from pre-fatigue to post-fatigue TTDPM despite a significant decrease in isometric knee flexion strength (P<0.01) and flexion/extension ratio (P<0.05) following fatigue. No significant correlations were observed between strength or physiological variables and changes in TTDPM from pre- to post-fatigue in extension or flexion. Flexion/extension ratio was significantly correlated with pre-fatigue TTDPM in extension (r=-0.231, P<0.05). Peak oxygen uptake was significantly correlated with pre-fatigue (r=-0.500, P<0.01) and post-fatigue (r=-0.520, P<0.05) TTDPM in extension. No significant relationships were demonstrated between musculoskeletal and physiological characteristics and changes in TTDPM following fatigue. The results suggest that highly trained individuals may have better proprioception, and that the high fitness level of subjects in this investigation may have contributed to absence of TTDPM deficits following fatigue despite reaching a high level of perceptual and physiological fatigue. Future studies should consider various subject populations, other musculoskeletal strength characteristics, and different modalities of proprioception to determine the most important contributions to proprioceptive changes following fatigue

    Provider Insight on Surmounting Specialty Practice Challenges to Improve Tdap Immunization Rates among Pregnant Women

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    Background Pertussis, or “whooping cough,” is an acute, contagious pulmonary disease that, despite being vaccine-preventable, has become an increasingly widespread problem in the United States. As a result, the Advisory Committee on Immunization Practices and American College of Obstetricians and Gynecologists updated recommendations stating clinicians should give a Tdap dose during every pregnancy, preferably at 27–36 weeks. Despite this recommendation, reported Tdap vaccine receipt rates during pregnancy vary from 16–61%, and previous studies have shown that clinician recommendation and vaccine administration are strongly associated with vaccine uptake among pregnant women. Methods Our aim was to inform new strategies to increase uptake of the Tdap vaccine among pregnant women and, ultimately, reduce pertussis-related morbidityand mortality in infants. We conducted interviewswith a sample of 24 ob-gyns. We subsequently performed grounded theory analyses of transcripts using deductive and inductive coding strategies followed by intercoder reliability assessment. Results All physicians interviewed were familiar with the most recent recommendation of giving the Tdap vaccine during the third trimester of every pregnancy, and the majority of physicians stated that they felt that the vaccine was important and effective due to the transfer of pertussis antibodies from the mother to the fetus. Most physicians indicated that they recommended the vaccine to patients during pregnancy, but not all reported administering it on site because it was not stocked at their practice. Implementation challenges for physicians included insurance reimbursement and other challenges (i.e., patient refusal). Tdap vaccinationduring pregnancy was a lower clinical priority for some physicians. Physicians recognized the benefits associated with Tdap vaccination during pregnancy. Conclusions Findings indicate while most ob-gyns recognize the benefits of Tdap and recommend vaccination during pregnancy, barriers such as insurance reimbursement and financial concerns for the practice can outweigh the perceived benefits. This resulted in some ob-gyns reporting choosing not to stock and administer the vaccine in their practice. Recommendations to address these concerns include 1) structural support for Tdap vaccine administration in ob-gyns practices; 2) Continuing medical education-equivalent educational interventions that address management techniques, vaccine coding, and other relevant information; and 3) interventions to assist physicians in communicating the importance of Tdap vaccination during pregnancy

    Cool Companions to White Dwarf Stars from the Two Micron All Sky Survey All Sky Data Release

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    We present the culmination of our near-infrared survey of the optically spectroscopically identified white dwarf stars from the McCook and Sion catalog, conducted using photometric data from the Two Micron All Sky Survey final All Sky Data Release. The color selection technique, which identifies candidate binaries containing a white dwarf and a low-mass stellar (or substellar) companion via their distinctive locus in the near-infrared color-color diagram, is demonstrated to be simple to apply and to yield candidates with a high rate of subsequent confirmation. We recover 105 confirmed binaries, and identify 27 firm candidates (19 of which are new to this work) and 21 tentative candidates (17 of which are new to this work) from the 2MASS data. Only a small number of candidates from our survey have likely companion spectral types later than M5, none of which is an obvious L-type (i.e., potential brown dwarf) companion. Only one previously known white dwarf + brown dwarf binary is detected. This result is discussed in the context of the 2MASS detection limits, as well as other recent observational surveys that suggest a very low rate of formation (or survival) for binary stars with extreme mass ratios

    Cultural Differences in Perception of Heroes: Greece, India, and the USA

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    Abstract: Hypothesis: The cultural background of an individual will have a significant effect on their perception of heroes. The purpose of this study was to investigate how one’s cultural background may affect one’s perception of heroes. The results of Study 1 revealed significant cultural differences in ratings of heroic traits. Study 2 employed a trait-sorting and hero-sorting task to explore underlying categories of traits and heroes across cultures. The results again revealed substantial cultural differences, suggesting that heroes, heroic traits, and heroism in general are all constructions of one’s culture and nationality
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