144 research outputs found

    A rotating three component perfect fluid source and its junction with empty space-time

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    The Kerr solution for empty space-time is presented in an ellipsoidally symmetric coordinate system and it is used to produce generalised ellipsoidal metrics appropriate for the generation of rotating interior solutions of Einstein's equations. It is shown that these solutions are the familiar static perfect fluid cases commonly derived in curvature coordinates but now endowed with rotation. The resulting solutions are also discussed in the context of T-solutions of Einstein's equations and the vacuum T-solution outside a rotating source is presented. The interior source for these solutions is shown not to be a perfect fluid but rather an anisotropic three component perfect fluid for which the energy momentum tensor is derived. The Schwarzschild interior solution is given as an example of the approach.Comment: 14 page

    Sport culture and communication among middle school athletes, parents, and staff: A qualitative study

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    Middle school (MS) is an intermediary level of education between elementary and secondary school that typically includes students aged 10–15 years. There is limited research within the MS sport setting, particularly related to sport-related injury prevention. This qualitative study aimed to better understand the sport culture within MS sports and the communication strategies used among invested groups (i.e., athletes, parents, staff inclusive of coaches and school nurses). Semi-structured interviews were conducted with 19 athletes, 20 parents, and 18 staff (e.g., coaches, school nurses) from seven MS in two school districts during the 2018/19 and 2019/20 school years. Topics focused on understanding school- and sport-related factors related to education, safety, and communication. Analysis used a consensual qualitative research tradition, in which the research team discussed individually developed themes and categories from transcribed interviews, with the goal of coming to a consensus and creating a codebook. Throughout the coding process, the research team would reconvene to discuss coding decisions until consensus was reached. This study focuses on the themes of sport culture and communication. Dominant categories identified within sport culture related to participants noting why they were interested in MS sports, and their struggles with their perceived roles and engagement (e.g., helping parents stay engaged, finding coaches, oversight of school nurses). Competitiveness and safety could have conflicting roles and priority. Dominant categories identified within communication centered around limited communication between coaches and parents. Technological assistance (e.g., phone apps, websites) was available, but often varied by school and sport. Concussions were seldom discussed unless during the preseason meeting or when one occurred. Findings highlight that the MS sport settings may struggle with incorporating primary prevention into their cultures and ensuring reliable communication among individuals. Novel and tailored approaches to injury prevention are needed to help ensure buy-in and proper implementation

    Association between Sensation-Seeking Behaviors and Concussion-Related Knowledge, Attitudes, Perceived Norms, and Care-Seeking Behaviors among Collegiate Student-Athletes

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    There are limited data connecting personality and behavioral tendencies and traits related to concussion care-seeking/disclosure behaviors and minimal research exists surrounding the relationship between risky behaviors, sensation-seeking, and concussion-related outcomes. This study examined the association between sensation-seeking and a student-athlete’s concussion-related knowledge, attitudes, perceived social norms, and concussion care-seeking/disclosure behaviors (intention to disclose concussion symptoms, perceived control over symptom disclosure, self-removal from play due to concussion symptoms, continued play with concussion symptoms, and disclosure of all concussions at the time of injury). The current study utilized a retrospective cohort of collegiate student-athletes at a single National Collegiate Athletic Association Division I institution. Separate multivariable linear regression models estimating mean differences (MD) and 95% Confidence Intervals (CI) estimated the association between sensation-seeking and concussion knowledge, concussion attitudes, and perceived social norms. Separate multivariable binomial regression models estimating adjusted prevalence ratios (PR) and 95%CI estimated the association between sensation-seeking and intention to disclose concussion symptoms, perceived control over symptom disclosure, self-removal from play due to concussion symptoms, continued play with concussion symptoms, and disclosure of all concussions at the time of injury. All models were adjusted for sex, sport participation, and concussion history. Higher sensation-seeking was significantly associated with less favorable concussion attitudes (adjusted MD = 1.93; 95%CI =-3.04,-0.83), less favorable perceived social norms surrounding concussion (adjusted MD =-1.39; 95%CI =-2.06,0.72), and continuing to play while experiencing concussion symptoms (adjusted PR = 1.50; 95%CI = 1.10, 2.06). Studentathletes with increased sensation-seeking could be at risk for failing to disclose a concussion, decreasing athlete safety and resulting in less optimal care post-injury. Results will inform future theory-based concussion education programs which consider behavioral tendencies and traits as well as sport culture to promote concussion care-seeking/disclosure and individualized interventions based on risky behavior engagement

    One-dimensional quantum channel and Hawking radiation of the Kerr and Kerr-Newman black holes

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    In this paper, we review the one-dimensional quantum channel and investigate Hawking radiation of bosons and fermions in Kerr and Kerr-Newman black holes. The result shows the Hawking radiation can be described by the quantum channel. The thermal conductances are derived and related to the black holes' temperatures.Comment: V2, 12 pages. Typo correcte

    Clustering Algorithms: Their Application to Gene Expression Data

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    Gene expression data hide vital information required to understand the biological process that takes place in a particular organism in relation to its environment. Deciphering the hidden patterns in gene expression data proffers a prodigious preference to strengthen the understanding of functional genomics. The complexity of biological networks and the volume of genes present increase the challenges of comprehending and interpretation of the resulting mass of data, which consists of millions of measurements; these data also inhibit vagueness, imprecision, and noise. Therefore, the use of clustering techniques is a first step toward addressing these challenges, which is essential in the data mining process to reveal natural structures and iden-tify interesting patterns in the underlying data. The clustering of gene expression data has been proven to be useful in making known the natural structure inherent in gene expression data, understanding gene functions, cellular processes, and subtypes of cells, mining useful information from noisy data, and understanding gene regulation. The other benefit of clustering gene expression data is the identification of homology, which is very important in vaccine design. This review examines the various clustering algorithms applicable to the gene expression data in order to discover and provide useful knowledge of the appropriate clustering technique that will guarantee stability and high degree of accuracy in its analysis procedure

    Genetics of coronary artery calcification among African Americans, a meta-analysis

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    Background: Coronary heart disease (CHD) is the major cause of death in the United States. Coronary artery calcification (CAC) scores are independent predictors of CHD. African Americans (AA) have higher rates of CHD but are less well-studied in genomic studies. We assembled the largest AA data resource currently available with measured CAC to identify associated genetic variants.Methods: We analyzed log transformed CAC quantity (ln(CAC + 1)), for association with ~2.5 million single nucleotide polymorphisms (SNPs) and performed an inverse-variance weighted meta-analysis on results for 5,823 AA from 8 studies. Heritability was calculated using family studies. The most significant SNPs among AAs were evaluated in European Ancestry (EA) CAC data; conversely, the significance of published SNPs for CAC/CHD in EA was queried within our AA meta-analysis.Results: Heritability of CAC was lower in AA (~30%) than previously reported for EA (~50%). No SNP reached genome wide significance (p < 5E-08). Of 67 SNPs with p < 1E-05 in AA there was no evidence of association in EA CAC data. Four SNPs in regions previously implicated in CAC/CHD (at 9p21 and PHACTR1) in EA reached
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