Mechanical Properties of Bulk Metallic Glasses and Composites

We have studied the mechanical properties of monolithic bulk metallic glasses and composite in the La based alloys. La₈₆₋yAl₁₄(Cu, Ni)y (y=24 to 32) alloy systems was used to cast the in-situ structure and subsequently tested under compression. We found that the ductility of the monolithic is actually poorer than that of the fully crystalline composite.Singapore-MIT Alliance (SMA

On the Topology of Black Hole Event Horizons in Higher Dimensions

In four dimensions the topology of the event horizon of an asymptotically flat stationary black hole is uniquely determined to be the two-sphere $S^2$. We consider the topology of event horizons in higher dimensions. First, we reconsider Hawking's theorem and show that the integrated Ricci scalar curvature with respect to the induced metric on the event horizon is positive also in higher dimensions. Using this and Thurston's geometric types classification of three-manifolds, we find that the only possible geometric types of event horizons in five dimensions are $S^3$ and $S^2 \times S^1$. In six dimensions we use the requirement that the horizon is cobordant to a four-sphere (topological censorship), Friedman's classification of topological four-manifolds and Donaldson's results on smooth four-manifolds, and show that simply connected event horizons are homeomorphic to $S^4$ or $S^2\times S^2$. We find allowed non-simply connected event horizons $S^3\times S^1$ and $S^2\times \Sigma_g$, and event horizons with finite non-abelian first homotopy group, whose universal cover is $S^4$. Finally, following Smale's results we discuss the classification in dimensions higher than six.Comment: 12 pages, minor edits 27/09/0

Level-Spacing Distributions and the Bessel Kernel

The level spacing distributions which arise when one rescales the Laguerre or Jacobi ensembles of hermitian matrices is studied. These distributions are expressible in terms of a Fredholm determinant of an integral operator whose kernel is expressible in terms of Bessel functions of order $\alpha$. We derive a system of partial differential equations associated with the logarithmic derivative of this Fredholm determinant when the underlying domain is a union of intervals. In the case of a single interval this Fredholm determinant is a Painleve tau function.Comment: 18 pages, resubmitted to make postscript compatible, no changes to manuscript conten

On Orthogonal and Symplectic Matrix Ensembles

The focus of this paper is on the probability, $E_\beta(0;J)$, that a set $J$ consisting of a finite union of intervals contains no eigenvalues for the finite $N$ Gaussian Orthogonal ($\beta=1$) and Gaussian Symplectic ($\beta=4$) Ensembles and their respective scaling limits both in the bulk and at the edge of the spectrum. We show how these probabilities can be expressed in terms of quantities arising in the corresponding unitary ($\beta=2$) ensembles. Our most explicit new results concern the distribution of the largest eigenvalue in each of these ensembles. In the edge scaling limit we show that these largest eigenvalue distributions are given in terms of a particular Painlev\'e II function.Comment: 34 pages. LaTeX file with one figure. To appear in Commun. Math. Physic

Fredholm Determinants, Differential Equations and Matrix Models

Orthogonal polynomial random matrix models of NxN hermitian matrices lead to Fredholm determinants of integral operators with kernel of the form (phi(x) psi(y) - psi(x) phi(y))/x-y. This paper is concerned with the Fredholm determinants of integral operators having kernel of this form and where the underlying set is a union of open intervals. The emphasis is on the determinants thought of as functions of the end-points of these intervals. We show that these Fredholm determinants with kernels of the general form described above are expressible in terms of solutions of systems of PDE's as long as phi and psi satisfy a certain type of differentiation formula. There is also an exponential variant of this analysis which includes the circular ensembles of NxN unitary matrices.Comment: 34 pages, LaTeX using RevTeX 3.0 macros; last version changes only the abstract and decreases length of typeset versio

“Write here, sanctuary” Creative writing for refugees and people seeking asylum

Background There are few research studies reporting findings from creative writing groups amongst refugees and people seeking asylum. This study evaluates the educational, wellbeing, social and satisfaction outcomes of writing groups across three cities in the UK. Methods This study employs a mixed-method design comprising: a thematic analysis of writers’ (facilitators) diaries, demographic and satisfaction survey and 14 qualitative interviews. Results The project delivered a creative writing programme for refugees and people seeking asylum in three UK cities. This evaluation has determined that it provided both educational and wellbeing outcomes for 144 attendees. Participants asserted that they had improved their English language and wellbeing. Satisfaction was extremely high across the cities. Participants reported increased confidence and an increased sense of hope. Conclusions Professionally-led creative writing groups may be effective in enabling people to help come to terms with past experiences and find ways of coping for the future

Time-dependent Stochastic Modeling of Solar Active Region Energy

A time-dependent model for the energy of a flaring solar active region is presented based on a stochastic jump-transition model (Wheatland and Glukhov 1998; Wheatland 2008; Wheatland 2009). The magnetic free energy of the model active region varies in time due to a prescribed (deterministic) rate of energy input and prescribed (random) flare jumps downwards in energy. The model has been shown to reproduce observed flare statistics, for specific time-independent choices for the energy input and flare transition rates. However, many solar active regions exhibit time variation in flare productivity, as exemplified by NOAA active region AR 11029 (Wheatland 2010). In this case a time-dependent model is needed. Time variation is incorporated for two cases: 1. a step change in the rates of flare jumps; and 2. a step change in the rate of energy supply to the system. Analytic arguments are presented describing the qualitative behavior of the system in the two cases. In each case the system adjusts by shifting to a new stationary state over a relaxation time which is estimated analytically. The new model retains flare-like event statistics. In each case the frequency-energy distribution is a power law for flare energies less than a time-dependent rollover set by the largest energy the system is likely to attain at a given time. For Case 1, the model exhibits a double exponential waiting-time distribution, corresponding to flaring at a constant mean rate during two intervals (before and after the step change), if the average energy of the system is large. For Case 2 the waiting-time distribution is a simple exponential, again provided the average energy of the system is large. Monte Carlo simulations of Case~1 are presented which confirm the analytic estimates. The simulation results provide a qualitative model for observed flare statistics in active region AR 11029.Comment: 25 pages, 9 figure

Amplitude measurements of Faraday waves

A light reflection technique is used to measure quantitatively the surface elevation of Faraday waves. The performed measurements cover a wide parameter range of driving frequencies and sample viscosities. In the capillary wave regime the bifurcation diagrams exhibit a frequency independent scaling proportional to the wavelength. We also provide numerical simulations of the full Navier-Stokes equations, which are in quantitative agreement up to supercritical drive amplitudes of 20%. The validity of an existing perturbation analysis is found to be limited to 2.5% overcriticaly.Comment: 7 figure

Pharmacological Emergency management of Agitation in Children and Young people: protocol for a randomised controlled trial of intraMuscular medication (PEAChY-M)

Introduction: Acute severe behavioural disturbance (ASBD) is a condition seen with increasing frequency in emergency departments (EDs) in adults and young people. Despite the increasing number of presentations and significant associated risks to patients, families and caregivers, there is limited evidence to guide the most effective pharmacological management in children and adolescents. The aim of this study is to determine whether a single dose of intramuscular olanzapine is more effective than intramuscular droperidol at successfully sedating young people with ASBD requiring intramuscular sedation. Methods and analysis: This study is a multicentre, open-label, superiority randomised controlled trial. Young people aged between 9 and 17 years and 364 days presenting to an ED with ASBD who are deemed to require medication for behavioural containment will be recruited to the study. Participants will be randomised in a 1:1 allocation between a single weight-based dose of intramuscular olanzapine and intramuscular droperidol. The primary outcome is the proportion of participants who achieve successful sedation at 1-hour post randomisation without the need for additional sedation. Secondary outcomes will include assessing for adverse events, additional medications provided in the ED, further episodes of ASBD, length of stay in the ED and hospital and satisfaction with management. Effectiveness will be determined using an intention-to-treat analysis, with medication efficacy determined as part of the secondary outcomes using a per-protocol analysis. The primary outcome of successful sedation at 1 hour will be presented as a percentage within each treatment group, with comparisons presented as a risk difference with its 95% CIs. Ethics and dissemination: Ethics approval was received from the Royal Children’s Hospital Human Research Ethics Committee (HREC/69948/RCHM-2021). This incorporated a waiver of informed consent for the study. The findings will be disseminated in a peer-reviewed journal and at academic conferences. Trial registration number: ACTRN12621001238864.Elyssia M Bourke, Meredith L Borland, Amit Kochar, Shane George, Deborah Shellshear, Shefali Jani, Kent Perkins, Doris Tham, Michael Solomon Gordon, Kate Klein, Chidambaram Prakash, Katherine Lee, Andrew Davidson, Jonathan C Knott, Simon Craig, Franz E Babl, On behalf of the Paediatric research in Emergency Departments International Collaborative (PREDICT