1,202 research outputs found

    Unified picture of Q-balls and boson stars via catastrophe theory

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    We make an analysis of Q-balls and boson stars using catastrophe theory, as an extension of the previous work on Q-balls in flat spacetime. We adopt the potential V3(ϕ)=m22ϕ2μϕ3+λϕ4V_3(\phi)={m^2\over2}\phi^2-\mu\phi^3+\lambda\phi^4 for Q-balls and that with μ=0\mu =0 for boson stars. For solutions with grr11|g^{rr}-1|\sim 1 at its peak, stability of Q-balls has been lost regardless of the potential parameters. As a result, phase relations, such as a Q-ball charge versus a total Hamiltonian energy, approach those of boson stars, which tell us an unified picture of Q-balls and boson stars.Comment: 10 pages, 13 figure

    Factors Impacting Perceived Quality in School Organizations

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    This paper presents the findings of studies conducted at Iowa State University of public schools in Iowa in the area of perceived quality assessment. Demographic characteristics of the respondents on the Perceived Quality Assessment Instrument from forty-four school districts were described by position, home annual income, gender, age, level of education, and years experience in current or a similar job. The research project undertaken incorporated several studies of quality improvement characteristics of public schools. The project resulted in a compendium of coordinated research aimed at learning more about the relationships and effects of quality improvement efforts with other factors of school district operations

    Information Consumer or Product?: Algorithmic Literacy

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    A brief essay of the importance of being aware of your online privacy, algorithm bias, filter bubbles, and the sale online personal data. A starting place with provide resources to be a better user of the internet and more informed information consumer

    Health Disparities Among Racial and Ethnic Minority Firefighters

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    ABSTRACT Background: Racial/ethnic minorities are substantially underrepresented in the fire service and this situation is unique when compared to similarly mentally and physically demanding and hazardous occupations such as the military and law enforcement. There is little systematic research to provide greater clarity about this significant disparity. The purpose of this study is to examine physical and behavioral health issues of racial/ethnic minority firefighters when compared to their white, non-Hispanic counterparts and potentially identify areas for future research that might assist in improving their substantial underrepresentation. Materials and Methods: We report the results of a secondary analysis of data combining the baseline evaluations of two different firefighter health studies, the Firefighter Injury and Risk Evaluation (FIRE) and Fuel 2 Fight (F2F) studies. Male career firefighters (N=1,404) were from 31 fire departments across the US and its territories. White, non-Hispanic firefighters comprised 72.5% of the sample (n=1,018) and 27.5% classified themselves as a racial/ethnic minority. Firefighters who agreed to participate comprised 94% (F2F) and 97% (FIRE) of those available and all underwent assessments including body composition, fitness, and general/behavioral health, and job satisfaction. Results: We examined differences in health and job status between minority and non-minority firefighters and between firefighters in minority- (MDCs) and white-dominated communities (WDCs). After adjusting for potential confounds, there were significant main effects for the individual minority status vs. non-minority status on both BMI and BF%, indicating that minority firefighters had significantly higher average BMI (28.8±0.3kg/m2) and BF% (24.7± 0.7%) when compared to their white, non-Hispanic colleagues (27.7±0.2kg/m2and 23.1±0.6% for BMI and BF%, respectively). Minority firefighters also were 59% more likely to be obese (adjusted [A]OR=1.59; 95% CI=1.16-2.18). Firefighters serving in MDCs reported significantly more poor health days (Mean±SE; 3.2±0.2 days) than firefighters serving in WDCs (2.8±0.2 days; p=0.038). In addition, minority firefighters reported significantly more poor health days (3.6±0.4 days) than their non-minority colleagues (2.8±0.2 days; p=0.003), while the interaction indicates that minority firefighters in MDCs reported more poor health days than the other groups (p Conclusions: Individual and community minority status (i.e., ethnic density effect) were both significantly associated with a number of important health status indicators, with racial/ethnic minority firefighters demonstrating greater risk for unfavorable body composition and more poor physical health days. In addition, minority firefighters in WDCs reported the highest prevalence of lifetime diagnosis of depression by a physician, while minority firefighters in MDCs had the lowest. Many of these health status indicators have recently been studied within the context of experiences with discrimination, demonstrating that racial discrimination is associated with greater risk for obesity, depression, and poor physical and mental health and could be contributing to health disparities and potentially negatively impacting racial/ethnic minority firefighter health, safety, and retention

    THE EFFECT OF COMPRESSION TIGHTS AND DURATION OF TESTING ON CONTINUOUS JUMPING MECHANICAL POWER

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    INTRODUCTION: In order to improve their performance, athletes seek advancements in technology, such as clothing. Manufacturers of compression tights, advertise that their product adds support to lower extremity musculature, thus may slow the onset of fatigue. Few scientific studies, however, have been conducted to identify how advancements in apparel influence an athlete’s performance (Kraemer et al., 1996). The purpose of the present study was to identify the effects of compression tights on mechanical power for continuous jumping. Secondly, the effect of duration on the mechanical power output by using Bosco’s method (1983) over 15, 30, 45, and 60 sec time-frames, as well as the interaction between apparel and duration

    Pulsive feedback control for stabilizing unstable periodic orbits in a nonlinear oscillator with a non-symmetric potential

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    We examine a strange chaotic attractor and its unstable periodic orbits in case of one degree of freedom nonlinear oscillator with non symmetric potential. We propose an efficient method of chaos control stabilizing these orbits by a pulsive feedback technique. Discrete set of pulses enable us to transfer the system from one periodic state to another.Comment: 11 pages, 4 figure

    Mean-field dynamics of a Bose-Einstein condensate in a time-dependent triple-well trap: Nonlinear eigenstates, Landau-Zener models and STIRAP

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    We investigate the dynamics of a Bose--Einstein condensate (BEC) in a triple-well trap in a three-level approximation. The inter-atomic interactions are taken into account in a mean-field approximation (Gross-Pitaevskii equation), leading to a nonlinear three-level model. New eigenstates emerge due to the nonlinearity, depending on the system parameters. Adiabaticity breaks down if such a nonlinear eigenstate disappears when the parameters are varied. The dynamical implications of this loss of adiabaticity are analyzed for two important special cases: A three level Landau-Zener model and the STIRAP scheme. We discuss the emergence of looped levels for an equal-slope Landau-Zener model. The Zener tunneling probability does not tend to zero in the adiabatic limit and shows pronounced oscillations as a function of the velocity of the parameter variation. Furthermore we generalize the STIRAP scheme for adiabatic coherent population transfer between atomic states to the nonlinear case. It is shown that STIRAP breaks down if the nonlinearity exceeds the detuning.Comment: RevTex4, 7 pages, 11 figures, content extended and title/abstract change

    Neighborhood Environment Perceptions and the Likelihood of Smoking and Alcohol Use

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    Citation: Jitnarin, N., Heinrich, K. M., Haddock, C. K., Hughey, J., Berkel, L., & Poston, W. S. C. (2015). Neighborhood Environment Perceptions and the Likelihood of Smoking and Alcohol Use. International Journal of Environmental Research and Public Health, 12(1), 784-799. doi:10.3390/ijerph120100784Neighborhood characteristics are important correlates for a variety of health outcomes. Among several health risk behaviors, smoking and alcohol use have significant consequences. Perceptions of neighborhood problems are associated with depressive symptoms, lower physical activity, and lower quality of life. However, it is unclear which perceived aspects of neighborhoods might be related to smoking and drinking. We examined whether perceived neighborhood characteristics were associated with smoking and drinking patterns using data from US metropolitan Midwestern area adults. Participants completed surveys including sociodemographic characteristics, neighborhood perceptions, behavioral and psychological health. For men, negative perceptions of neighborhood infrastructures were significant predictors for smoking and binge drinking. Among women, no perceived environmental factors were associated with smoking or drinking. However, education was a significant negative predictor for smoking. As age increased, the likelihood of using cigarettes, heavy and binge drinking in women decreased significantly. Depression was a positive predictor for smoking and heavy drinking in men and women, respectively. These findings indicate that the perceived neighborhood infrastructure was predictive of health behaviors among men, even after adjusting for key confounders. Closer attention may need to be paid to the role of neighborhood environmental characteristics along with individual-level characteristics in influencing unhealthy behaviors

    The Prognostic Significance of the Preoperative Full Blood Count after Resection of Colorectal Liver Metastases

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    Introduction. Increased preoperative platelet and neutrophil counts are risk factors for decreased survival in several different malignancies. Our aim was to investigate the relationship between overall or disease-free survival after resection of CRLM and the preoperative haematological parameters. Methods. We reviewed a cohort of 140 patients who underwent resection of CRLM with curative intent, utilising prospectively maintained databases. Patient demographics, operative details, FBC, CRP, INR, histopathology results, and survival data were examined. Kaplan-Meier survival and Cox regression analyses were used to determine the impact of all variables on survival. Results. 140 patients (96 males) with a median age of 67 years (range 33–82 years) underwent resection of CRLM. A significant correlation was exhibited between preoperative platelet count and neutrophil count (rho = 0.186, P = .028). When modelled as continuous covariates in a Cox regression hazards, an increased preoperative platelet (P = .02) and neutrophil counts (P ≤ .001) were significantly associated with overall survival. Of the haematological parameters assessed only preoperative platelet count showed a strong trend of association with disease free survival; however this failed to reach statistical significance (P = .076). Conclusions. Increased preoperative platelet and neutrophil counts are independent risk factors for decreased survival in patients undergoing resection of CRLM in our series of patients. These findings require validation in larger studies to determine their relationship with survival. Further research into the role of these cell types in tumour progression, particularly in the development and inhibition of angiogenesis, is warranted
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