The eCommentary Machine Project

The eCommentary Machine web application ("eComma") enables groups of students, scholars, or general readers to build collaborative commentaries on a text and to search, display, and share those commentaries online

Zeroing in on more photons and gluons

We discuss radiation zeros that are found in gauge tree amplitudes for processes involving multi-photon emission. Previous results are clarified by examples and by further elaboration. The conditions under which such amplitude zeros occur are identical in form to those for the single-photon zeros, and all radiated photons must travel parallel to each other. Any other neutral particle likewise must be massless (e.g. gluon) and travel in that common direction. The relevance to questions like gluon jet identification and computational checks is considered. We use examples to show how certain multi-photon amplitudes evade the zeros, and to demonstrate the connection to a more general result, the decoupling of an external electromagnetic plane wave in the ``null zone". Brief comments are made about zeros associated with other gauge-boson emission.Comment: 26 page

Compact QED3 with theta term and axionic confining strings

We discuss three dimensional compact QED with a theta term due to an axionic field. The variational gauge invariant functional is considered and it is shown that the ground state energy is independent of theta in a leading approximation. The mass gap of the axionic field is found to be dependent upon theta, the mass gap of the photon field and the scalar potential. The vacuum expectation of the Wilson loop is shown to be independent of theta in a leading approximation, to obey the area law and to lead to confinement. We also briefly discuss the properties of axionic confining strings.Comment: 35 pages, LaTex, typing error correcte

Discovery of an ultramassive pulsating white dwarf

We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/- 0.06, which corresponds to a mass of 1.20 +/- 0.03 Msun. Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multi-periodic luminosity variations at timescales ranging from roughly 425-595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains SNe Ia progenitor systems.Comment: 5 pages, 3 figures, Astrophysical Journal Letters, 771, L2 (2013

Outcomes of Naviculectomy for Severe Recurrent Clubfoot Deformity

Background: Naviculectomy was originally described for resistant congenital vertical talus deformity but was later expanded to use in rigid cavus deformity. This study reviews the operative outcomes of complete excision of the navicular for recurrent deformity in the talipes equinovarus (TEV) population. Methods: After institutional review board approval, all patients undergoing naviculectomy at a single institution were identified. Clinical, radiographic, and pedobarographic data (minimum 2 years’ follow-up) were reviewed. Results: Twelve patients (14 feet) with TEV from 1984 to 2019 were included. All feet had minimum 1 prior operative intervention on the affected foot (mean age = 4.0 years, range 0.2-14.5), with 8/14 having at least 3 prior operative procedures. Complete navicular excision with concomitant procedures was performed in all patients (mean age = 11.7 years, range 5.5-16.1). Mean clinical follow-up from naviculectomy was 5.1 years (range, 2.2-11.2). During follow-up, 6 patients required subsequent surgery, most often secondary to pain and progressive deformity. One patient underwent elective below-knee amputation of the affected extremity. Of the remaining 11 patients, 7 of 11 reported continued pain and 8 of 11 maintained adequate range of motion at the ankle at the most recent follow-up. Conclusion: Clinical follow-up demonstrated deteriorating results in a large percentage of patients. The high rate of additional procedures and continued pain in the current series suggests that even as a salvage procedure, naviculectomy may not provide adequate results for patients. Level of Evidence: Level IV, case series

Evaluation of a measles vaccine campaign by oral-fluid surveys in a rural Kenyan district: interpretation of antibody prevalence data using mixture models

We evaluated the effectiveness of a measles vaccine campaign in rural Kenya, based on oral-fluid surveys and mixture-modelling analysis. Specimens were collected from 886 children aged 9 months to 14 years pre-campaign and from a comparison sample of 598 children aged 6 months post-campaign. Quantitative measles-specific antibody data were obtained by commercial kit. The estimated proportions of measles-specific antibody negative in children aged 0–4, 5–9 and 10–14 years were 51%, 42% and 27%, respectively, pre- campaign and 18%, 14% and 6%, respectively, post-campaign. We estimate a reduction in the proportion susceptible of 65–78%, with ~85% of the population recorded to have received vaccine. The proportion of ‘weak’ positive individuals rose from 35% pre-campaign to 54% post-campaign. Our results confirm the effectiveness of the campaign in reducing susceptibility to measles and demonstrate the potential of oral-fluid studies to monitor the impact of measles vaccination campaigns

Recall, perceptions and determinants of receiving physical activity advice amongst cancer survivors: a mixed-methods survey

Purpose: This study explored cancer survivors’ views and experiences of receiving physical activity advice post-diagnosis. We also determined the influence of sociodemographic characteristics on the recall of physical activity advice and whether receiving advice was associated with meeting physical activity guidelines. Methods: An anonymised, mixed-methods, 27-item survey was distributed to cancer survivors via online cancer communities in the UK. Results: Of the 242 respondents, 52% recalled receiving physical activity advice. Of those who recalled receiving advice, only 30% received guidance on type of physical activity and 14% were referred to another source of information or exercise specialist. Advice was most often given after treatment cessation, with only 19% of respondents receiving advice during active treatment. Most respondents (56%) expressed a need for further information. There was no evidence of associations between sociodemographic characteristics and recall of physical activity advice. However, cancer survivors who perceived the physical activity advice they received as being appropriate (odds ratio [OR] 3.8, 95% confidence interval [95% CI]: 1.4–10.7) and those with a higher level of education (OR 3.2, 95% CI: 1.8–5.8) were more likely to meet aerobic exercise guidelines. Females were less likely to meet resistance exercise guidelines than males (OR 0.44, 95% CI: 0.21–0.90). Conclusion: There is scope to improve the provision of physical activity advice in cancer care by providing advice in a timely manner after diagnosis, referring patients to a suitable exercise or rehabilitation specialist when indicated, and using a tailored approach to ensure the advice is appropriate for specific sociodemographic groups