2,094 research outputs found

    Factors associated with injuries among first-division Rwandan female soccer players

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    Background: Female soccer has grown tremendously in the last decade. Studies have suggested that female soccer players are more susceptible to injuries than their male counterparts, and their vulnerability is due mainly to intrinsic factors such as their anatomical and physiological structure. Objectives: To establish factors associated with soccer injuries among first-division Rwandan female soccer players. Methods: In a descriptive cross-sectional study, self-administered questionnaires were used to investigate factors associated with injuries among soccer players. Results: Almost half of the 300 participants (45%) indicated having been injured in the three seasons prior to the study. More than half (52.6%) were recurrent injuries. The ankle was the most common body part injured. Intrinsic factors associated with injuries were age, excessive ankle range of motion, pre-menstrual symptoms, and previous injury (p-value < 0.05). Extrinsic factors associated with injuries were use of oral contraceptive pills, (OCP), competition level, use of protective equipment, and player’s position. Conclusions: The large number of recurring injuries was notable, emphasizing the importance of prevention strategies and access to adequately trained medical personnel as research has shown a significant reduction in the prevalence of recurring injuries after the introduction of effective prevention programmes

    Testing a Grassroots Citizen Science Venture Using Open Design, “the Bee Lab Project”

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    The Bee Lab project applies Citizen Science and Open Design to beekeeping, enabling participants to construct monitoring devices gathering reciprocal data, motivating participants and third parties. The presented approach uses design workshops to provide insight into the design of kits, user motivations, promoting reciprocal interests and address community problems. This paper signposts issues and opportunities in the process of designing Citizen Science tools for communities using Open Design to solve individual problems, including: downloadable design for social/local change, laypeople creating technology and repairable kits

    Transformation of in-plane ρ(T)\rho (T) in YBa2Cu3O7δYBa_{2}Cu_{3}O_{7-\delta} at fixed oxygen content

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    This paper reveals the origin of variation in the magnitude and temperature dependence of the normal state resistivity frequently observed in different YBCO single crystal or thin film samples with the same TcT_{c}. We investigated temperature dependence of resistivity in YBa2Cu3O7δYBa_{2}Cu_{3}O_{7-\delta} thin films with 7- δ=6.95\delta = 6.95 and 6.90, which were subjected to annealing in argon at 400-420 K (120140oC120-140^{o}C). Before annealing these films exhibited a non-linear ρab(T)\rho_{ab}(T), with a flattening below 230 K, similar to ρb(T)\rho_{b}(T) and ρab(T)\rho_{ab}(T) observed in untwinned and twinned YBCO crystals, respectively. For all films the annealing causes an increase of resistivity and a transformation of ρab(T)\rho_{ab}(T) from a non-linear dependence towards a more linear one (less flattening). In films with 7- δ=6.90\delta = 6.90 the increase of resistivity is also associated with an increase in TcT_{c}. We proposed the model that provides an explanation of these phenomena in terms of thermally activated redistribution of residual O(5) oxygens in the chain-layer of YBCO. Good agreement between the experimental data for ρab(t,T)\rho_{ab}(t,T), where t is the annealing time, and numerical calculations was obtained.Comment: 8 pages, 9 figures, submitted to PR

    Fluctuations of an evaporating black hole from back reaction of its Hawking radiation: Questioning a premise in earlier work

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    This paper delineates the first steps in a systematic quantitative study of the spacetime fluctuations induced by quantum fields in an evaporating black hole. We explain how the stochastic gravity formalism can be a useful tool for that purpose within a low-energy effective field theory approach to quantum gravity. As an explicit example we apply it to the study of the spherically-symmetric sector of metric perturbations around an evaporating black hole background geometry. For macroscopic black holes we find that those fluctuations grow and eventually become important when considering sufficiently long periods of time (of the order of the evaporation time), but well before the Planckian regime is reached. In addition, the assumption of a simple correlation between the fluctuations of the energy flux crossing the horizon and far from it, which was made in earlier work on spherically-symmetric induced fluctuations, is carefully analyzed and found to be invalid. Our analysis suggests the existence of an infinite amplitude for the fluctuations of the horizon as a three-dimensional hypersurface. We emphasize the need for understanding and designing operational ways of probing quantum metric fluctuations near the horizon and extracting physically meaningful information.Comment: 10 pages, REVTeX; minor changes, a few references added and a brief discussion of their relevance included. To appear in the proceedings of the 10th Peyresq meeting. Dedicated to Rafael Sorkin on the occasion of his 60th birthda

    Noise Kernel and Stress Energy Bi-Tensor of Quantum Fields in Hot Flat Space and Gaussian Approximation in the Optical Schwarzschild Metric

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    Continuing our investigation of the regularization of the noise kernel in curved spacetimes [N. G. Phillips and B. L. Hu, Phys. Rev. D {\bf 63}, 104001 (2001)] we adopt the modified point separation scheme for the class of optical spacetimes using the Gaussian approximation for the Green functions a la Bekenstein-Parker-Page. In the first example we derive the regularized noise kernel for a thermal field in flat space. It is useful for black hole nucleation considerations. In the second example of an optical Schwarzschild spacetime we obtain a finite expression for the noise kernel at the horizon and recover the hot flat space result at infinity. Knowledge of the noise kernel is essential for studying issues related to black hole horizon fluctuations and Hawking radiation backreaction. We show that the Gaussian approximated Green function which works surprisingly well for the stress tensor at the Schwarzschild horizon produces significant error in the noise kernel there. We identify the failure as occurring at the fourth covariant derivative order.Comment: 21 pages, RevTeX

    Religious Values, Practices and Pregnancy Outcomes: A Comparison of the Impact of Sect and Mainstream Christian Affiliation

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    In this report 6566 women enrolled in the Mater-University of Queensland Study of Pregnancy (MUSP) were separated into three groups; members of religious sects, Christians who attend church frequently and Christians who are infrequent attenders. These three groups, respectively labelled Christian sects, Christian attenders and lukewarm Christians were compared on a number of social background, lifestyle and pregnancy outcome variables. The sect members appeared to have the most favourable health, lifestyles and healthy babies at delivery, though this latter finding appears attributable to specific characteristics of the mother and her lifestyle. On most measures the children of lukewarm Christians appear to manifest the worst health while Christian attenders form a group whose children's health is between that of sect members and lukewarm Christians

    Intermediate band to conduction band optical absorption in ZnTeO

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    ZnTe doped with high concentrations of oxygen has been proposed in previous works as an intermediate band (IB) material for photovoltaic applications. The existence of extra optical transitions related to the presence of an IB has already been demonstrated in this material and it has been possible to measure the absorption coefficient of the transitions from the valence band (VB) to the IB. In this study, we present the first measurement of the absorption coefficient associated with transitions from the IB to the conduction band (CB) in ZnTeO. The samples used are 4-mum-thick ZnTe layers with or without O in a concentration ~10 19 cm -3, which have been grown on semiinsulating GaAs substrates by molecular beam epitaxy (MBE). The IB-CB absorption coefficient peaks for photon energies ~0.4 eV. It is extracted from reflectance and transmittance spectra measured using Fourier transform infrared (FTIR) spectroscopy. Under typical FTIR measurement conditions (low light intensity, broadband spectrum), the absorption coefficient in IB-to-CB transitions reaches 700 cm -1. This is much weaker than the one observed for VB-IB absorption. This result is consistent with the fact that the IB is expected to be nearly empty of electrons under equilibrium conditions in ZnTe(O)

    Tomato: a crop species amenable to improvement by cellular and molecular methods

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    Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

    Intermediate Band to Conduction Band optical absorption in ZnTe:O

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    ZnTe doped with high concentrations of oxygen has been proposed in previous works as intermediate band (IB) material for photovoltaic applications. The existence of extra optical transitions related to the presence of an IB has already been demonstrated in this material and it has been possible to measure the absorption coefficient of the transitions from the valence band (VB) to the IB. In this work we present the first measurement of the absorption coefficient associated to transitions from the IB to the conduction band (CB) in ZnTe:O. The samples used are 4 ?m thick ZnTe layers with or without O in a concentration ~ 1019 cm-3, which have been grown on semi-insulating GaAs substrates by molecular beam epitaxy (MBE). The IB-CB absorption coefficient peaks for photon energies ~ 0.4 eV. It is extracted from reflectance and transmittance spectra measured using Fourier Transform Infrared (FTIR) spectroscopy. Under typical FTIR measurement conditions (low light intensity, broadband spectrum) the absorption coefficient in IB-to-CB transitions reaches 700 cm-1. This is much weaker than the one observed for VB-IB absorption. This result is consistent with the fact that the IB is expected to be nearly empty of electrons under equilibrium conditions in ZnTe(:O). The absorption for VB to IB transitions is also observed in the same samples through reflectance measurements performed in the visible range using a monochromator. These measurements are compared with the quantum efficiency (QE) from solar cells fabricated under similar conditions
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