From Peierls brackets to a generalized Moyal bracket for type-I gauge theories

In the space-of-histories approach to gauge fields and their quantization, the Maxwell, Yang--Mills and gravitational field are well known to share the property of being type-I theories, i.e. Lie brackets of the vector fields which leave the action functional invariant are linear combinations of such vector fields, with coefficients of linear combination given by structure constants. The corresponding gauge-field operator in the functional integral for the in-out amplitude is an invertible second-order differential operator. For such an operator, we consider advanced and retarded Green functions giving rise to a Peierls bracket among group-invariant functionals. Our Peierls bracket is a Poisson bracket on the space of all group-invariant functionals in two cases only: either the gauge-fixing is arbitrary but the gauge fields lie on the dynamical sub-space; or the gauge-fixing is a linear functional of gauge fields, which are generic points of the space of histories. In both cases, the resulting Peierls bracket is proved to be gauge-invariant by exploiting the manifestly covariant formalism. Moreover, on quantization, a gauge-invariant Moyal bracket is defined that reduces to i hbar times the Peierls bracket to lowest order in hbar.Comment: 14 pages, Late

Self-force on a scalar charge in radial infall from rest using the Hadamard-WKB expansion

We present an analytic method based on the Hadamard-WKB expansion to calculate the self-force for a particle with scalar charge that undergoes radial infall in a Schwarzschild spacetime after being held at rest until a time t = 0. Our result is valid in the case of short duration from the start. It is possible to use the Hadamard-WKB expansion in this case because the value of the integral of the retarded Green's function over the particle's entire past trajectory can be expressed in terms of two integrals over the time period that the particle has been falling. This analytic result is expected to be useful as a check for numerical prescriptions including those involving mode sum regularization and for any other analytical approximations to self-force calculations.Comment: 22 pages, 2 figures, Physical Review D version along with the corrections given in the erratu

Path-Integral Formulation of Pseudo-Hermitian Quantum Mechanics and the Role of the Metric Operator

We provide a careful analysis of the generating functional in the path integral formulation of pseudo-Hermitian and in particular PT-symmetric quantum mechanics and show how the metric operator enters the expression for the generating functional.Comment: Published version, 4 page

Evaluation of the InDUCKtion project at UCL

Executive summary: There is evidence that a good induction to university life can help with student retention; however, there is also a danger of overwhelming students during the intense period of fresher’s week. Under the auspices of a small grant from the Higher Education Academy’s ‘Changing the Learning Landscape’ funding stream, staff at two universities (University College London and Southampton Solent University) collaborated to produce an innovative and engaging induction project entitled ‘InDUCKtion’, based on the idea of an induction duck being a fun character for students to interact with. At UCL, the InDUCKtion duck existed in the form of a physical plastic duck included in international postgraduate student induction packs, and they were encouraged to take photos of themselves in and around UCL and London as part of a photo challenge using social media. It was anticipated that this would enable students to familiarise themselves with the locale, make friends and have fun at the same time. The InDUCKtion duck was also evident on flyers and posters with QR codes advertising an online tour to enable students to gain an accelerated familiarisation with the campus and its facilities. Within UCL, the project was a collaborative, cross-departmental venture instigated by members of UCL’s E-Learning Environments (ELE) working in partnership with the Centre for the Advancement of Learning and Teaching (CALT) and Student Support and Wellbeing (SSW). The logistics of the project meant that the team members also had to liaise with a number of other individuals and departments around UCL, to help promote and implement the project. Despite a rapid following on Twitter in a relatively short period, a reasonable hit rate on the QR code for the main page of the online tour resource, and some engagement with the photo challenges using social media, participation in the project was lower than anticipated. Lessons learned from an evaluation perspective revealed that adding another activity to an already overwhelming fresher’s week was problematic, despite its innovative and interactive nature. The use of QR codes was problematic for a number of reasons, and the project needed more buy-in from student representatives and academics to provide institutional endorsement. Recommendations for future instances of the project include securing student representation and academic endorsement, integrating the activity with parallel induction activities – particularly with academic departments, replacing QR codes with an alternative technology-enhanced learning approach and optimising the learning design to better motivate students and promote groupwork

EUS-Guided Pancreatic Cyst Ablation: a Clinical and Technical Review

Purpose of Review Pancreatic cystic lesions represent a growing public health dilemma, particularly as our population ages and cross-sectional imaging becomes more sensitive. Mucinous cysts carry a clinically significant risk of developing pancreatic cancer, which carries an extremely poor prognosis. Determining which cysts will develop cancer may be challenging, and surgical resection of the pancreas carries significant morbidity. The goal of this paper is to review the rationale for cyst ablation and discuss prior and current research on cyst ablation techniques and efficacy. Indications, contraindications, and factors related to optimal patient selection are outlined. Recent Findings Endoscopic ultrasound-guided chemoablation of pancreatic cysts has been performed in neoplastic cysts, with varying levels of efficacy. Safety concerns arose due to the risk of pancreatitis in alcohol-based treatments; however, the most recent data using a non-alcohol chemoablation cocktail suggests that ablation is effective without the need for alcohol, resulting in a significantly more favorable adverse event profile. Summary Endoscopic ultrasound-guided chemoablation of neoplastic pancreatic cysts is a promising, minimally invasive approach for treatment of cysts, with recent significant advances in safety and efficacy, suggesting that it should play a role in the treatment algorithm

Counter-term charges generate bulk symmetries

We further explore the counter-term subtraction definition of charges (e.g., energy) for classical gravitating theories in spacetimes of relevance to gauge/gravity dualities; i.e., in asymptotically anti-de Sitter spaces and their kin. In particular, we show in general that charges defined via the counter-term subtraction method generate the desired asymptotic symmetries. As a result, they can differ from any other such charges, such as those defined by bulk spacetime-covariant techniques, only by a function of auxiliary non-dynamical structures such as a choice of conformal frame at infinity (i.e., a function of the boundary fields alone). Our argument is based on the Peierls bracket, and in the AdS context allows us to demonstrate the above result even for asymptotic symmetries which generate only conformal symmetries of the boundary (in the chosen conformal frame). We also generalize the counter-term subtraction construction of charges to the case in which additional non-vanishing boundary fields are present.Comment: 13 pages, Latex, no figures, v3: errors fixed, boundary terms carefully controlled, awkward assumption removed, references update

Gravitational Self Force in a Schwarzschild Background and the Effective One Body Formalism

We discuss various ways in which the computation of conservative Gravitational Self Force (GSF) effects on a point mass moving in a Schwarzschild background can inform us about the basic building blocks of the Effective One-Body (EOB) Hamiltonian. We display the information which can be extracted from the recently published GSF calculation of the first-GSF-order shift of the orbital frequency of the last stable circular orbit, and we combine this information with the one recently obtained by comparing the EOB formalism to high-accuracy numerical relativity (NR) data on coalescing binary black holes. The information coming from GSF data helps to break the degeneracy (among some EOB parameters) which was left after using comparable-mass NR data to constrain the EOB formalism. We suggest various ways of obtaining more information from GSF computations: either by studying eccentric orbits, or by focussing on a special zero-binding zoom-whirl orbit. We show that logarithmic terms start entering the post-Newtonian expansions of various (EOB and GSF) functions at the fourth post-Newtonian (4PN) level, and we analytically compute the first logarithm entering a certain, gauge-invariant "redshift" GSF function (defined along the sequence of circular orbits).Comment: 44 page

Angiolymphoid hyperplasia with eosinophilia treated with Mohs micrographic surgery

A 60-year-old healthy man presented with several enlarging, tender, spontaneously bleeding, and episodically pruritic nodules on his ear. Five agminated pink-red papulonodules of the superior postauricular sulcus were noted on examination. Pathological examination revealed a lobular dermal vascular proliferation with plump endothelial cells protruding into the lumen in a hobnail pattern, along with a dense perivascular inflammatory infiltrate composed of plasma cells, lymphocytes, and numerous eosinophils. The diagnosis of angiolymphoid hyperplasia with eosinophilia was confirmed. After discussing treatment modalities, the patient opted for Mohs micrographic surgery (MMS). Three stages of MMS were able to remove all large vessel involvement and clear the peripheral margins, but the tumor had a complex branching pattern of growth in the deep bed of the wound with numerous tiny foci remaining. Owing to risk of disfigurement, no further excision was undertaken. The area was reconstructed with a temporalis fascia flap and a full-thickness skin graft. Despite remaining microscopic disease, the patient remained without recurrence or symptoms at one year of follow up

How Students Benefit by Attending Formal Review Sessions Before Taking Written Examinations

The purpose of this investigation was to determine whether review sessions prior to written examinations affect university student performance on the examinations. It was hypothesized that students would benefit by attending formal review sessions before taking written examinations. A prospective investigational design was used to test the hypothesis. An online review demonstrates the claimed-importance of preparatory programs before taking standardized examinations such as the GRE, SAT, or MCAT (1-4). 800score GRE Prep Software guarantees that one will achieve their highest possible score (1). GRE Comprehensive Success System claims that over 16,000 test takers passed the GRE because of their system (2). Secretsstudyguide guarantees to increase ones SAT test scores in a few hours of study (3). MCAT Practice Tests states that the most effective way to prepare for your test is to simply take their practice tests (4). Although it makes intuitive sense, there is a paucity of controlled-research demonstrating the effectiveness of formal review before taking examinations in the university classroom