Elastic deformations of compact stars

We prove existence of solutions for an elastic body interacting with itself through its Newtonian gravitational field. Our construction works for configurations near one given by a self-gravitating ball of perfect fluid. We use an implicit function argument. In so doing we have to revisit some classical work in the astrophysical literature concerning linear stability of perfect fluid stars. The results presented here extend previous work by the authors, which was restricted to the astrophysically insignificant situation of configurations near one of vanishing stress. In particular, "mountains on neutron stars", which are made possible by the presence of an elastic crust in neutron stars, can be treated using the techniques developed here.Comment: 29 page

Optimal Trade-Off Between Economic Activity and Health During an Epidemic

This paper considers a simple model where a social planner can influence the spread-intensity of an infection wave, and, consequently, also the economic activity and population health, through a single parameter. Population health is assumed to only be negatively affected when the number of simultaneously infected exceeds health care capacity. The main finding is that if (i) the planner attaches a positive weight on economic activity and (ii) it is more harmful for the economy to be locked down for longer than shorter time periods, then the optimal policy is to (weakly) exceed health care capacity at some time.Comment: 12 pages, 2 figure

Journal Staff

Introduction Cognitive behaviour therapy delivered in the format of guided self-help via the internet has been found to be effective for a range of conditions, including depression and anxiety disorders. Recent results indicate that guided self-help via the internet is a promising treatment format also for psychodynamic therapy. However, to date and to our knowledge, no study has evaluated internet-delivered psychodynamic therapy as a transdiagnostic treatment. The affect-phobia model of psychopathology by McCullough et al provides a psychodynamic conceptualisation of a range of psychiatric disorders. The aim of this study will be to test the effects of a transdiagnostic guided self-help treatment based on the affect-phobia model in a sample of clients with depression and anxiety. Methods and analysis This study will be a randomised controlled trial with a total sample size of 100 participants. The treatment group receives a 10-week, psychodynamic, guided self-help treatment based on the transdiagnostic affect-phobia model of psychopathology. The treatment consists of eight text-based treatment modules and includes therapist contact in a secure online environment. Participants in the control group receive similar online therapist support without any treatment modules. Outcome measures are the 9-item Patient Health Questionnaire Depression Scale and the 7-item Generalised Anxiety Disorder Scale (GAD-7). Process measures that concerns emotional processing and mindfulness are included. All outcome and process measures will be administered weekly via the internet and at 6-month follow-up. Discussion This trial will add to the body of knowledge on internet-delivered psychological treatments in general and to psychodynamic treatments in particular. We also hope to provide new insights in the effectiveness and working mechanisms of psychodynamic therapy based on the affect-phobia model

The Meanings of Communion: Anglican Identities, the Sexuality Debates, and Christian Relationality

Recent discussions of the international Anglican Communion have been dominated by notions of a \'crisis\' and \'schism\' resulting from conflicts over issues of homosexuality. Existing accounts of the Communion have often tended to emphasise the perspectives of those most vocal in the debates (particularly bishops, senior clergy, and pressure groups) or to engage in primarily theological analysis. This article examines the nature of the purported \'crisis\' from the perspectives of Anglicans in local parishes in three different national contexts: England, South Africa, and the US. Unusually for writing on the Communion, attention is simultaneously given to parishes that have clear pro-gay stances, those that largely oppose the acceptance of homosexual practice, and those with more ambivalent positions. In doing so, the article offers new insights for the growing body of literature on lesbian, gay, bisexual, and transgender Christians, as well as wider discussions about the contested nature of contemporary Anglican and other Christian identities. Key themes include the divergent ways in which respondents felt (and did not feel) connections to the spatially distant \'others\' with whom they are in Communion; the complex relationships and discordances between parish, denominational, and Communion-level identities; and competing visions of the role of the Communion in producing unity or preserving diversity amongst Anglicans.Anglican Communion; Sexuality; Christianity; Religious Identities

Effects of ascorbic acid on chemical and thermal corneal burns: A comprehensive literature review

Background: Ascorbic acid has been suggested to be effective against chemical burns. It was first tested in rabbits before being implemented in human subjects. It was proven to be useful in treatments for different conditions, such as corneal chemical and thermal burns. Herein, we aimed to review the effects of ascorbic acid in the healing of chemical and thermal corneal burns. Methods: We performed an electronic search of English literature in MEDLINE, clinicaltrials.gov, and Google Scholar, without time constraints. Articles were selected based on inclusion and exclusion criteria, using they keywords “Corneal Burn,†AND “Corneal Ulcer,†AND “Vitamin C.†This yielded 17 English language articles focused on the effect of vitamin C on chemical or thermal corneal burn-induced ulcers. Results: The 17 eligible studies that fulfilled the inclusion criteria included three retrospective, nonrandomized, comparative studies on human subjects and 14 in vivo, laboratory-based studies on rabbits (12 studies), rats (one study), as well as guinea-pigs (one study). Most studies showed benefits in using vitamin C as a prophylactic treatment to delay or stop corneal ulcer formation after chemical or thermal corneal burn. Conclusions: Vitamin C is a very basic, inexpensive prescription and can be used to treat corneal ulcers following a variety of corneal burns. This review highlights the necessity for conducting randomized controlled trials to investigate the prophylactic role of vitamin C and to determine its minimum required dose for the management of corneal ulcers after different types of corneal burns

Modulation-assisted tunneling in laser-fabricated photonic Wannier-Stark ladders

We observe Wannier-Stark localization in curved photonic lattices, realized using arrays of evanescently coupled optical waveguides. By correctly tuning the strength of inter-site coupling in the lattice, we observe that Wannier-Stark states become increasingly localized, and eventually fully localized to one site, as the curvature of the lattice is increased. We then demonstrate that tunneling can be successfully restored in the lattice by applying a sinusoidal modulation to the lattice position, an effect that is a direct analogue of photon-assisted tunneling. This precise tuning of the tunneling matrix elements, through laser-fabricated on-site modulations, opens a novel route for the creation of gauge fields in photonic lattices.Comment: 5 pages. Comments are welcom

Observation of pair tunneling and coherent destruction of tunneling in arrays of optical waveguides

We report on the experimental realization of a photonic system that simulates the one-dimensional two-particle Hubbard model. This analogy is realized by means of two-dimensional arrays of coupled optical waveguides, fabricated using femtosecond laser inscription. By tuning the analogous "interaction strength", we reach the strongly-interacting regime of the Hubbard Hamiltonian, and demonstrate the suppression of standard tunneling for individual "particles". In this regime, the formation of bound states is identified through the direct observation of pair tunneling. We then demonstrate the coherent destruction of tunneling (CDT) for the paired particles in the presence of an engineered oscillating force of high frequency. The precise control over the analogous "interaction strength" and driving force offered by our experimental system opens an exciting route towards quantum simulation of few-body physics in photonics.Comment: 4 pages, 4 figures, Appendi

Observation of a localized flat-band state in a photonic Lieb lattice

We show experimentally how a non-diffracting state can be excited in a photonic Lieb lattice. This lattice supports three energy bands, including a perfectly flat middle band, which corresponds to an infinite effective mass with zero dispersion. We show that a suitable optical input state can be prepared so as to only excite the flat band. We analyse, both experimentally and theoretically, the evolution of such photonic flat-band states, and show their remarkable robustness, even in the presence of disorder.Comment: Accepted for publication in Physical Review Letter

Experimental observation of anomalous topological edge modes in a slowly-driven photonic lattice

The discovery of the quantised Hall effect, and its subsequent topological explanation, demonstrated the important role topology can play in determining the properties of quantum systems. This realisation led to the development of topological band theory, where, in addition to band index and quasimomentum, Bloch bands are also characterised by a set of topological invariants. This topological theory can be readily extended to periodically-driven systems. In the limit of fast driving, the topology of the system can still be captured by the topological invariants used to describe static systems. In the limit of slow driving, however, situations can arise where standard topological invariants are zero, but yet, topologically protected edge modes are still observed. These "anomalous" topological edge modes have no static analogue, and are associated with a distinct topological invariant, which takes into account the full time-evolution over a driving period. Here we demonstrate the first experimental observation of such anomalous topological edge modes in an ultrafast-laser-inscribed photonic lattice. This inscription technique allows one to address each bond of a lattice independently and dynamically, generating a rich band structure with robust anomalous chiral edge modes and the potential for perfectly localised bulk states.Comment: 6 pages, 3 figures, supplementary materia

Utilising Spontaneous Conversational Speech in HMM-Based Speech Synthesis

Spontaneous conversational speech has many characteristics that are currently not well modelled in unit selection and HMM-based speech synthesis. But in order to build synthetic voices more suitable for interaction we need data that exhibits more conversational characteristics than the generally used read aloud sentences. In this paper we will show how carefully selected utterances from a spontaneous conversation was instrumental for building an HMM-based synthetic voices with more natural sounding conversational characteristics than a voice based on carefully read aloud sentences. We also investigated a style blending technique as a solution to the inherent problem of phonetic coverage in spontaneous speech data. But the lack of an appropriate representation of spontaneous speech phenomena probably contributed to results showing that we could not yet compete with the speech quality achieved for grammatical sentences