Baby Skyrmions in AdS

We study the baby Skyrme model in a pure AdS background without a mass term. The tail decays and scalings of massless radial solutions are demonstrated to take a similar form to those of the massive flat space model, with the AdS curvature playing a similar role to the flat space pion mass. We also numerically find minimal energy solutions for a range of higher topological charges and find that they form concentric ring-like solutions. Popcorn transitions (named in analogy with studies of toy models of holographic QCD) from an n layer to an n + 1-layer configuration are observed at topological charges 9 and 27 and further popcorn transitions for higher charges are predicted. Finally, a pointparticle approximation for the model is derived and used to successfully predict the ring structures and popcorn transitions for higher charge solitons

Baryons, salt and popcorn in holographic QCD

The Sakai-Sugimoto model is the leading model of holographic QCD. It has an effective five-dimensional description in which baryons correspond to the bulk topological solitons of a Yang-Mills-Chern-Simons theory. However, the large dimensionality of the model means studying soliton solutions either analytically or numerically is difficult. Sakai-Sugimoto solitons in the high density limit should provide an analogue of cold, dense QCD. Two competing theories for high-density solutions are the dyon salt model, in which the appropriate crystal is a salt-like arrangement of dyons, and the baryonic popcorn model in which a series of transitions occurs where the three-dimensional soliton crystal develops extra layers in the holographic direction. In this thesis we consider a range of low-dimensional analogues and approximations to the Sakai-Sugimoto model. We first investigate an O(3) sigma model stabilised by vector mesons, and a baby Skyrme model in pure AdS spacetime, before moving on to consider homogeneous ansätze in both the holographic baby Skyrme and full Sakai- Sugimoto models. In each case we look for analogues of the dyon salt and baryonic popcorn configurations, and find evidence for new features in the high-density regime of holographic QCD

Still an occupational hazard?:The relationship between homophobia, heteronormativity, student learning and performance, and an openly gay university lecturer

This study examined the complex relationship between homophobia, heteronormativity, and an openly gay lecturer in a British university setting. First, heterosexual undergraduate sports students’ levels of homophobia were recorded. Then, after taught sessions, participants were asked to estimate the frequency of homosexual-heterosexual examples and content used, as well as to complete tests to measure academic progress. This was followed by an end-of-course examination. Results indicated (a) no relationship between levels of homophobia and levels of heteronormativity; (b) that levels of heteronormativity and homophobia were unrelated to a student’s ability to learn from an openly gay lecturer or their examination performance; (c) the presence of an openly gay lecturer significantly reduced homophobia among undergraduate students. These findings offer support to gay educators by highlighting the minimal impact on student learning and performance from being open about their sexuality. Instead, these results suggest that being open about homosexuality could reduce homophobia among undergraduate students

Injuries in International Men’s Sixes Lacrosse: Injury Surveillance of the British Lacrosse Men’s National Team During a 9-Month Training Cycle Leading up to and Including The World Games 2022

OBJECTIVE: To describe the injury epidemiology of a men’s national Sixes lacrosse team across training and competition. DESIGN: Prospective observation study. METHODS: This study prospectively observed in- juries that occurred within a training and competition cycle of the British Men’s National Lacrosse team. Data were collected by the team physiotherapist, injury incidence was calculated, and data categorized into injury type, body part, and mechanism. RESULTS: Forty-three injuries occurred during Sixes competition. Injury incidence varied between practice and tournaments. Twelve percent of all injuries were time loss. Two thirds of the time, players continued playing following intervention. One in every 5 injuries was treated with self-management strate- gies. Injuries most frequently occurred in competitive matches (65%). Most injuries were sustained through a contact mechanism (49%) or an overload mechanism (37%). The most frequent injuries were contusions (26%) and muscle injuries (26%). The lower limb was the most frequently injured area (63%), with the lower leg predominantly being the most affected part of the lower limb (63%). CONCLUSIONS: To our knowledge, this is the first epidemiology study of Sixes lacrosse injuries. Further research is required to better understand the epidemiology and risk factors for injuries in Sixes lacrosse. JOSPT Open 2023;1(1):1-7. Epub: 19 June 2023. doi:10.2519/josptopen.2023.000

A Naive Bayes Source Classifier for X-ray Sources

The Chandra Carina Complex Project (CCCP) provides a sensitive X-ray survey of a nearby starburst region over >1 square degree in extent. Thousands of faint X-ray sources are found, many concentrated into rich young stellar clusters. However, significant contamination from unrelated Galactic and extragalactic sources is present in the X-ray catalog. We describe the use of a naive Bayes classifier to assign membership probabilities to individual sources, based on source location, X-ray properties, and visual/infrared properties. For the particular membership decision rule adopted, 75% of CCCP sources are classified as members, 11% are classified as contaminants, and 14% remain unclassified. The resulting sample of stars likely to be Carina members is used in several other studies, which appear in a Special Issue of the ApJS devoted to the CCCP.Comment: Accepted for the ApJS Special Issue on the Chandra Carina Complex Project (CCCP), scheduled for publication in May 2011. All 16 CCCP Special Issue papers are available at http://cochise.astro.psu.edu/Carina_public/special_issue.html through 2011 at least. 19 pages, 7 figure

Practical Issues in Imputation-Based Association Mapping

Imputation-based association methods provide a powerful framework for testing untyped variants for association with phenotypes and for combining results from multiple studies that use different genotyping platforms. Here, we consider several issues that arise when applying these methods in practice, including: (i) factors affecting imputation accuracy, including choice of reference panel; (ii) the effects of imputation accuracy on power to detect associations; (iii) the relative merits of Bayesian and frequentist approaches to testing imputed genotypes for association with phenotype; and (iv) how to quickly and accurately compute Bayes factors for testing imputed SNPs. We find that imputation-based methods can be robust to imputation accuracy and can improve power to detect associations, even when average imputation accuracy is poor. We explain how ranking SNPs for association by a standard likelihood ratio test gives the same results as a Bayesian procedure that uses an unnatural prior assumption—specifically, that difficult-to-impute SNPs tend to have larger effects—and assess the power gained from using a Bayesian approach that does not make this assumption. Within the Bayesian framework, we find that good approximations to a full analysis can be achieved by simply replacing unknown genotypes with a point estimate—their posterior mean. This approximation considerably reduces computational expense compared with published sampling-based approaches, and the methods we present are practical on a genome-wide scale with very modest computational resources (e.g., a single desktop computer). The approximation also facilitates combining information across studies, using only summary data for each SNP. Methods discussed here are implemented in the software package BIMBAM, which is available from http://stephenslab.uchicago.edu/software.html

The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity

We have made the largest-volume measurement to date of the transition to large-scale homogeneity in the distribution of galaxies. We use the WiggleZ survey, a spectroscopic survey of over 200,000 blue galaxies in a cosmic volume of ~1 (Gpc/h)^3. A new method of defining the 'homogeneity scale' is presented, which is more robust than methods previously used in the literature, and which can be easily compared between different surveys. Due to the large cosmic depth of WiggleZ (up to z=1) we are able to make the first measurement of the transition to homogeneity over a range of cosmic epochs. The mean number of galaxies N(<r) in spheres of comoving radius r is proportional to r^3 within 1%, or equivalently the fractal dimension of the sample is within 1% of D_2=3, at radii larger than 71 \pm 8 Mpc/h at z~0.2, 70 \pm 5 Mpc/h at z~0.4, 81 \pm 5 Mpc/h at z~0.6, and 75 \pm 4 Mpc/h at z~0.8. We demonstrate the robustness of our results against selection function effects, using a LCDM N-body simulation and a suite of inhomogeneous fractal distributions. The results are in excellent agreement with both the LCDM N-body simulation and an analytical LCDM prediction. We can exclude a fractal distribution with fractal dimension below D_2=2.97 on scales from ~80 Mpc/h up to the largest scales probed by our measurement, ~300 Mpc/h, at 99.99% confidence.Comment: 21 pages, 16 figures, accepted for publication in MNRA