Crystalline Order on a Sphere and the Generalized Thomson Problem

We attack generalized Thomson problems with a continuum formalism which exploits a universal long range interaction between defects depending on the Young modulus of the underlying lattice. Our predictions for the ground state energy agree with simulations of long range power law interactions of the form 1/r^{gamma} (0 < gamma < 2) to four significant digits. The regime of grain boundaries is studied in the context of tilted crystalline order and the generality of our approach is illustrated with new results for square tilings on the sphere.Comment: 4 pages, 5 eps figures Fig. 2 revised, improved Fig. 3, reference typo fixe

Detrimental effects of RNAi: a cautionary note on its use in Drosophila ageing studies

RNA interference (RNAi) provides an important tool for gene function discovery. It has been widely exploited in Caenorhabditis elegans ageing research because it does not appear to have any non-specific effects on ageing-related traits in that model organism. We show here that ubiquitous, adult-onset activation of the RNAi machinery, achieved by expressing a double stranded RNA targeting GFP or lacZ for degradation, or by increasing expression of Dicer substantially reduces lifespan in Drosophila melanogaster. Induction of GFPRNAi construct also alters the response of lifespan to nutrition, exacerbating the lifespan-shortening effects of food containing a high quantity of yeast. Our study indicates that activation of the RNAi machinery may have sequence-independent side-effects on lifespan, and that caution needs to be exercised when employing ubiquitous RNAi in Drosophila ageing studies. However, we also show that RNAi restricted to certain tissues may not be detrimental to lifespan

Protocol for a randomized, double blind, placebo controlled, crossover trial of Melatonin for treatment of Nocturia in adults with Multiple Sclerosis (MeNiMS)

Background: Nocturia (the symptom of needing to wake up to pass urine) is common in progressive Multiple Sclerosis (MS) patients. Moderate-to-severe nocturia affects quality of life, can exacerbate fatigue and may affect capacity to carry out daily activities. Melatonin is a natural hormone regulating circadian cycles, released by the pineal gland at night-time, and secretion is impaired in MS. Melatonin levels can be supplemented by administration in tablet form at bedtime. The aim of this study is to evaluate the effect of melatonin on mean number of nocturia episodes per night in MS patients. Secondary outcome measures will assess impact upon quality of life, urinated volumes, lower urinary tract symptoms (LUTS), cognition, sleep quality and sleep disturbance of partners. Methods: A randomized, double blind, placebo controlled, crossover trial consisting of two, six week treatment phases (active drug melatonin 2 mg or placebo), with a 1 month wash-out period in between. The primary outcome (change in nocturia episodes per night) in this two arm, two treatment, two period crossover design, will be objectively measured using frequency volume charts (FVC) at baseline and following both treatment phases. Questionnaires will be used to assess quality of life, sleep quality, safety and urinary tract symptoms. Qualitative interviews of participants and partners will explore issues including quality of life, mechanisms of sleep disturbance and impact of nocturia on partners. Discussion: This study will evaluate whether melatonin reduces the frequency of nocturia episodes in MS patients, and therefore whether 'Circadin' has the potential to reduce LUTS and fatigue, and improve cognition and overall quality of life. Trial registration: (EudraCT reference) 2012-00418321 registered: 25/01/13. ISRCTN Registry: ISRCTN38687869</p

Melting as a String-Mediated Phase Transition

We present a theory of the melting of elemental solids as a dislocation-mediated phase transition. We model dislocations near melt as non-interacting closed strings on a lattice. In this framework we derive simple expressions for the melting temperature and latent heat of fusion that depend on the dislocation density at melt. We use experimental data for more than half the elements in the Periodic Table to determine the dislocation density from both relations. Melting temperatures yield a dislocation density of (0.61\pm 0.20) b^{-2}, in good agreement with the density obtained from latent heats, (0.66\pm 0.11) b^{-2}, where b is the length of the smallest perfect-dislocation Burgers vector. Melting corresponds to the situation where, on average, half of the atoms are within a dislocation core.Comment: 18 pages, LaTeX, 3 eps figures, to appear in Phys. Rev.

Androgen receptor genotyping in a large Australasian cohort with androgen insensitivity syndrome; identification of four novel mutations

We genotyped the androgen receptor (AR) gene in 31 Australasian patients with androgen insensitivity syndrome (AIS). The entire coding region of AR was examined including analysis of polymorphic CAG and GGN repeats in all patients. AR defects were found in 66.7% (6/9) of patients with complete AIS (CAIS) and 13.6% (3/22) of patients with partial AIS (PAIS). A novel deletion (N858delG) leading to a premature stop codon was found in CAIS patient P1. CAIS patient P2 has a novel deletion (N2676delGAGT) resulting in a stop at codon 787. These mutations would result in inactivation of AR protein. A novel insertion of a cysteine residue in the first zinc finger of the AR DNA-binding domain (N2045_2047dupCTG) was found in CAIS patient P3. PAIS patient P4 has a novel amino acid substitution (Arg760Ser) in the AR ligand binding domain, which may impair ligand binding. Five patients were found to have previously reported AR mutations and no mutations were identified in the remaining patients

Liquid antiferromagnets in two dimensions

It is shown that, for proper symmetry of the parent lattice, antiferromagnetic order can survive in two-dimensional liquid crystals and even isotropic liquids of point-like particles, in contradiction to what common sense might suggest. We discuss the requirements for antiferromagnetic order in the absence of translational and/or orientational lattice order. One example is the honeycomb lattice, which upon melting can form a liquid crystal with quasi-long-range orientational and antiferromagnetic order but short-range translational order. The critical properties of such systems are discussed. Finally, we draw conjectures for the three-dimensional case.Comment: 4 pages RevTeX, 4 figures include

Socio-economic utility and chemical potential

In statistical physics, the conservation of particle number results in the equalization of the chemical potential throughout a system at equilibrium. In contrast, the homogeneity of utility in socio-economic models is usually thought to rely on the competition between individuals, leading to Nash equilibrium. We show that both views can be reconciled by introducing a notion of chemical potential in a wide class of socio-economic models, and by relating it in a direct way to the equilibrium value of the utility. This approach also allows the dependence of utility across the system to be determined when agents take decisions in a probabilistic way. Numerical simulations of a urban economic model also suggest that our result is valid beyond the initially considered class of solvable models.Comment: 6 pages, 3 figures, final versio

Refining and testing the diagnostic accuracy of an assessment tool (PAT-POPS) to predict admission and discharge of children and young people who attend an emergency department : protocol for an observational study

Background: Increasing attendances by children (aged 0–16 years) to United Kingdom Emergency Departments (EDs) challenges patient safety within the National Health Service (NHS) with health professionals required to make complex judgements on whether children attending urgent and emergency care services can be sent home safely or require admission. Health regulation bodies have recommended that an early identification systems should be developed to recognise children developing critical illnesses. The Pennine Acute Hospitals NHS Trust Paediatric Observation Priority Score (PAT-POPS) was developed as an ED-specific tool for this purpose. This study aims to revise and improve the existing tool and determine its utility in determining safe admission and discharge decision making. Methods/design: An observational study to improve diagnostic accuracy using data from children and young people attending the ED and Urgent Care Centre (UCC) at three hospitals over a 12 month period. The data being collected is part of routine practice; therefore opt-out methods of consent will be used. The reference standard is admission or discharge. A revised PAT-POPs scoring tool will be developed using clinically guided logistic regression models to explore which components best predict hospital admission and safe discharge. Suitable cut-points for safe admission and discharge will be established using sensitivity and specificity as judged by an expert consensus meeting. The diagnostic accuracy of the revised tool will be assessed, and it will be compared to the former version of PAT-POPS using ROC analysis. Discussion: This new predictive tool will aid discharge and admission decision-making in relation to children and young people in hospital urgent and emergency care facilities. Trial registration: NIHR RfPB Grant: PB-PG-0815-20034. ClinicalTrials.gov: 213469. Retrospectively registered on 11 April 2018. Keywords: Paediatric, Emergency department, Diagnostic accuracy, Early identification systems, screening tool, Observational, Early warning score, Early warning system, hospital admission

Size and emotion or depth and emotion? Evidence, using Matryoshka (Russian) dolls, of children using physical depth as a proxy for emotional charge

Background: The size and emotion effect is the tendency for children to draw people and other objects with a positive emotional charge larger than those with a negative or neutral charge. Here we explored the novel idea that drawing size might be acting as a proxy for depth (proximity).Methods: Forty-two children (aged 3-11 years) chose, from 2 sets of Matryoshka (Russian) dolls, a doll to represent a person with positive, negative or neutral charge, which they placed in front of themselves on a sheet of A3 paper. Results: We found that the children used proximity and doll size, to indicate emotional charge. Conclusions: These findings are consistent with the notion that in drawings, children are using size as a proxy for physical closeness (proximity), as they attempt with varying success to put positive charged items closer to, or negative and neutral charge items further away from, themselves

Decreased MCM2-6 in Drosophila S2 cells does not generate significant DNA damage or cause a marked increase in sensitivity to replication interference.

A reduction in the level of some MCM proteins in human cancer cells (MCM5 in U20S cells or MCM3 in Hela cells) causes a rapid increase in the level of DNA damage under normal conditions of cell proliferation and a loss of viability when the cells are subjected to replication interference. Here we show that Drosophila S2 cells do not appear to show the same degree of sensitivity to MCM2-6 reduction. Under normal cell growth conditions a reduction of >95% in the levels of MCM3, 5, and 6 causes no significant short term alteration in the parameters of DNA replication or increase in DNA damage. MCM depleted cells challenged with HU do show a decrease in the density of replication forks compared to cells with normal levels of MCM proteins, but this produces no consistent change in the levels of DNA damage observed. In contrast a comparable reduction of MCM7 levels has marked effects on viability, replication parameters and DNA damage in the absence of HU treatment