A survey on the English FA heading guidelines for youth soccer: Evidence of compliance, but with limited knowledge of safety

Soccer heading may be problematic for neurocognitive function. The English Football Association (FA) recently introduced guidelines in order to limit the number of headers within training for youth soccer. However, it remains to be seen what the influence of these guidelines has been on the leaders of soccer teams that are primarily responsible for implementing the guidelines. Thus, we aimed to explore grassroot youth coaches’ knowledge of, views on, and adherence to the heading guidelines. An online survey was distributed to team representatives across Local County FAs. The survey comprised of three sections: (1) background information, (2) heading practices including details on heading activities and views on heading safety, and (3) heading guidelines including levels of awareness, knowledge, and compliance. 240 coaches responded by stating they rarely (21%) or never (73%) practiced heading, although they mostly perceived heading as being somewhat safe (36%). While respondents indicated being only somewhat aware of the guidelines (43%), they scored very high on their perceived (92%) and actual (based on retrospective accounts of heading) (87%) compliance with the guidelines. There was a mixed perceived change within practice following the introduction of the guidelines (disagree = 26% vs. agree = 22%), and they were perceived as safe (86%) and appropriate (81%). Factors that were identified as being potential barriers were only marginally agreed upon (<30%) and tended to be related to in-game rules. While there is scope to successfully implement heading guidelines, there is some discrepancy between the requirements for heading safety and coaches’ knowledge

Relationship Between Proximal Articular Set Angle and Hallux Abducto Valgus

A study of radiographs from 50 males and 50 females was undertaken to determine whether a relationship existed between the proximal articular set angle and the hallux abductus angle. Gender differences in the relationship were also investigated. The normal range for the proximal articular set angle was –2.6° to 8.6°, with a mean of 5°. There was no significant difference in the mean values between males and females. A positive linear correlation between the proximal articular set angle and hallux abducto valgus deformity was found (R2 = 0.52), suggesting that an increased lateral tilt of the metatarsal head is one of the factors that lead to hallux abducto valgus deformity. The relationship between proximal articular set angle and hallux abducto valgus deformity was similar in males and females and did not account for the increased hallux deformity seen in females

Open-source development experiences in scientific software: the HANDE quantum Monte Carlo project

The HANDE quantum Monte Carlo project offers accessible stochastic algorithms for general use for scientists in the field of quantum chemistry. HANDE is an ambitious and general high-performance code developed by a geographically-dispersed team with a variety of backgrounds in computational science. In the course of preparing a public, open-source release, we have taken this opportunity to step back and look at what we have done and what we hope to do in the future. We pay particular attention to development processes, the approach taken to train students joining the project, and how a flat hierarchical structure aids communicationComment: 6 pages. Submission to WSSSPE

Accurate exchange-correlation energies for the warm dense electron gas

Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the $k$-space configuration path-integral formalism disagree by up to $\sim$$10$\% at certain reduced temperatures $T/T_F \le 0.5$ and densities $r_s \le 1$. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that DMQMC can calculate free energies directly and present exact free energies for $T/T_F \ge 1$ and $r_s \le 2$.Comment: Accepted version: added free energy data and restructured text. Now includes supplementary materia

Urothelial cells may indicate underlying bacteriuria in pregnancy at term: a comparative study

BACKGROUND: Urinary tract infection is common in pregnancy. Urine is sampled from by mid-stream collection (MSU). If epithelial cells are detected, contamination by vulvo-vagial skin and skin bacteria is assumed. Outside pregnancy, catheter specimen urine (CSU) is considered less susceptible to contamination. We compared MSU and CSU methods in term pregnancy to test these assumptions. METHODS: Healthy pregnant women at term gestation (n = 32, median gestation 38 + 6 weeks, IQR 37 + 6–39 + 2) undergoing elective caesarean section provided a MSU and CSU for paired comparison that were each analysed for bacterial growth and bladder distress by fresh microscopy, sediment culture and immunofluorescent staining. Participants completed a detailed questionnaire on lower urinary tract symptoms. Epithelial cells found in urine were tested for urothelial origin by immunofluorescent staining of Uroplakin III (UP3), a urothelial cell surface glycoprotein. Urothelial cells with closely associated bacteria, or “clue cells”, were also counted. Wilcoxons signed rank test was used for paired analysis. RESULTS: Women reported multiple lower urinary tract symptoms (median 3, IQR 0–8). MSU had higher white blood cell counts (median 67 vs 46, z = 2.75, p = 0.005) and epithelial cell counts (median 41 vs 22, z = 2.57, p = 0.009) on fresh microscopy. The proportion of UP3+ cells was not different (0.920 vs 0.935, z = 0.08, p = 0.95), however MSU had a higher proportion of clue cells (0.978 vs 0.772, z = 3.17, p = 0.001). MSU had more bacterial growth on sediment culture compared to CSU specimens (median 8088 total cfu/ml vs 0, z = 4.86, p = 0.001). Despite this, routine laboratory cultures reported a negative screening culture for 40.6% of MSU specimens. CONCLUSION: Our findings have implications for the correct interpretation of MSU findings in term pregnancy. We observed that MSU samples had greater bacterial growth and variety when compared to CSU samples. The majority of epithelial cells in both MSU and CSU samples were urothelial in origin, implying no difference in contamination. MSU samples had a higher proportion of clue cells to UP3+ cells, indicating a greater sensitivity to bacterial invasion. Urinary epithelial cells should not be disregarded as contamination, instead alerting us to underlying bacterial activity

Quantifying high-speed running in rugby league: An insight into practitioner applications and perceptions

High-speed running has previously been documented as a popular metric among rugby league researchers. Researchers place importance on high-speed running due to its inclusion in assessing the demands of training and match-play to help prescribe accurate training loads and recovery methods. However, there is currently no information available as to how important rugby league practitioners perceive high-speed running to be and what methods are currently used by practitioners to quantify high-speed running. Furthermore, practitioners’ perceptions of specific benefits, barriers and motivations when selecting high-speed running methods are also currently limited. Therefore, the aim of this study was to provide a current insight into the practice and perceptions of rugby league practitioners when quantifying high-speed running. This study surveyed practitioners working in the European Super League (n = 12) and the Australasian National Rugby League (n = 11). Ranking analysis established high-speed running to be the most important metric for both training practice and match-play. Absolute high-speed running thresholds were applied by 52% of respondents (n = 12) with the most common being 5.5 m·s−1 (n = 9). Individualised high-speed running thresholds were applied by 48% of respondents (n = 11) with the most common approach implementing peak sprint speed methods (n = 9). Absolute high-speed running thresholds are perceived to permit better group data comparison, whereas individualised methods are perceived to permit better interpretation of high-speed running data. Ultimately, practitioners are motivated to implement their chosen methods with the possibility of more accurately prescribed high-speed running thresholds, although the impracticality of specific testing procedures may act as a barrier

The Antiferromagnetic Band Structure of La2CuO4 Revisited

Using the Becke-3-LYP functional, we have performed band structure calculations on the high temperature superconductor parent compound, La2CuO4. Under the restricted spin formalism (rho(alpha) equal to rho(beta)), the R-B3LYP band structure agrees well with the standard LDA band structure. It is metallic with a single Cu x2-y2/O p(sigma) band crossing the Fermi level. Under the unrestricted spin formalism (rho(alpha) not equal to rho(beta)), the UB3LYP band structure has a spin polarized antiferromagnetic solution with a band gap of 2.0 eV, agreeing well with experiment. This state is 1.0 eV (per formula unit) lower than that calculated from the R-B3LYP. The apparent high energy of the spin restricted state is attributed to an overestimate of on-site Coulomb repulsion which is corrected in the unrestricted spin calculations. The stabilization of the total energy with spin polarization arises primarily from the stabilization of the x2-y2 band, such that the character of the eigenstates at the top of the valence band in the antiferromagnetic state becomes a strong mixture of Cu x2-y2/O p(sigma) and Cu z2/O' p(z). Since the Hohenberg-Kohn theorem requires the spin restricted and spin unrestricted calculations give exactly the same ground state energy and total density for the exact functionals, this large disparity in energy reflects the inadequacy of current functionals for describing the cuprates. This calls into question the use of band structures based on current restricted spin density functionals (including LDA) as a basis for single band theories of superconductivity in these materials.Comment: 13 pages, 8 figures, to appear in Phys. Rev. B, for more information see http://www.firstprinciples.co