Nonlinear Competition Between Small and Large Hexagonal Patterns

Recent experiments by Kudrolli, Pier and Gollub on surface waves, parametrically excited by two-frequency forcing, show a transition from a small hexagonal standing wave pattern to a triangular ``superlattice'' pattern. We show that generically the hexagons and the superlattice wave patterns bifurcate simultaneously from the flat surface state as the forcing amplitude is increased, and that the experimentally-observed transition can be described by considering a low-dimensional bifurcation problem. A number of predictions come out of this general analysis.Comment: 4 pages, RevTex, revised, to appear in Phys. Rev. Let

Motion of Isolated bodies

It is shown that sufficiently smooth initial data for the Einstein-dust or the Einstein-Maxwell-dust equations with non-negative density of compact support develop into solutions representing isolated bodies in the sense that the matter field has spatially compact support and is embedded in an exterior vacuum solution

Heterodyne detection of the 752.033-GHz H2O rotational absorption line

A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K

Comparative Study of Different Lightweight Head Protection Systems with Full-Face Visors for Humanitarian Deminers

A key component of any Personal Protective Ensemble (PPE) for demining is the helmet and/or face shield. For obvious reasons, protecting the face of a deminer is of utmost importance in case of an accidental detonation of a mine. Currently, a wide range of head and face protective devices are available for the deminer, and this study attempts to evaluate these devices from several perspectives

Taux de récurrence chez les enfants signalés à une direction de la protection de la jeunesse entre 1998 et 2002

L’application de la Loi sur la protection de la jeunesse repose sur le signalement d’une situation qui compromet la sécurité ou le développement d’un enfant. Depuis quelques années les intervenants des centres jeunesse constatent qu’un nombre élevé d’enfants font l’objet d’un nouveau signalement au fil des ans : on parle alors de récurrence. Les études menées sur ce sujet rapportent des taux de récurrence variant entre 18 % et 60 %. Or, une majorité d’études s’appuient sur de petits échantillons, et non sur des cohortes, pour établir les taux de récurrence. L’objectif de la présente étude est d’estimer la récurrence en s’appuyant sur cinq cohortes d’enfants (n = 8 738) dont le signalement a été analysé par la direction de la protection de la jeunesse d’un centre jeunesse entre 1998 et 2002. Les résultats indiquent que 24,5 % des enfants évalués avaient fait l’objet d’une enquête antérieurement et qu’un enfant sur six (15,8 %) avait reçu des services des centres jeunesse. Finalement, les prévalences les plus fortes s’observent chez les garçons, dans le groupe d’âge des 13-17 ans et chez ceux qui sont signalés pour une problématique d’abandon et de négligence.Over the past few years, caseworkers in Child Protection Centres in Quebec have noticed a recurrence of referrals for a significant number of children over time. Recent estimates of recurrence for children who received child protection services (CPS) range from 18 % to 60 %. Most studies base their rate on small samples or cases referred over a short period of time, and not on cohorts of CPS-evaluated children. The focus of this study is to estimate the recurrence rate using data from 5 cohorts of children referred and evaluated (n=8738) by a CPS between 1998 and 2002. Results show that 24.5 % of substantiated cases had been evaluated in the past by CPS, and one out of six children (15.8 %) had received CPS services. Boys, children in the 13-17 age group and cases referred for neglect or abandonment showed the highest recurrence rate

Radiative Transfer Equation Solver Module for Coupled Simulation of Hypersonic Flows

Accurate numerical modeling of the aerothermal environment around an ablation-cooled hypersonic re-entry vehicle requires high-fidelity models for processes such as non-equilibrium surface themochemistry, non-equilibrium pyrolysis chemistry, multi-scale radiation, spallation and charring. It is expected that, these models when utilized in a coupled manner will be able to accurately capture the possible nonlinear interactions between various phenomena in a computationally efficient manner. Development of a coupled radiative solver is currently being carried out as part of a joint effort between CFDRC, University of Michigan and University of Kentucky to develop a fully coupled method of simulating atmospheric entry flows and response of the thermal protection system. A key aspect of the project is development of a modular radiative transfer equation (RTE) solver which can be used in a tightly coupled manner with any hypersonic flow code. The code will be coupled with latest spectral property databases allowing almost line-by-line accuracy for radiative heat-fluxes on the spacecraft surface while still utilizing a multidimensional RTE formulation. The presentation will focus on architecture of the RTE solver, radiative property models that can be used in the solver and its interfacing with LeMANS aerothermal code for a simple demonstration case. The infrastructure to couple the solver with other codes of interest will be outlined

Critical Casimir force in 4^4He films: confirmation of finite-size scaling

We present new capacitance measurements of critical Casimir force-induced thinning of $^4$He films near the superfluid/normal transition, focused on the region below $T_{\lambda}$ where the effect is the greatest. $^4$He films of 238, 285, and 340 \AA thickness are adsorbed on N-doped silicon substrates with roughness $\approx 8 {\AA}$. The Casimir force scaling function $\vartheta$, deduced from the thinning of these three films, collapses onto a single universal curve, attaining a minimum $\vartheta = -1.30 \pm 0.03$ at $x=td^{1/\nu}=-9.7\pm 0.8 {\AA}^{1/\nu}$. The collapse confirms the finite-size scaling origin of the dip in the film thickness. Separately, we also confirm the presence down to $2.13 K$ of the Goldstone/surface fluctuation force, which makes the superfluid film $\sim 2 {\AA}$ thinner than the normal film.Comment: 4 pages, 3 figures, submitted to PR

Physiotherapy practice in the private sector: organizational characteristics and models.

BACKGROUND: Even if a large proportion of physiotherapists work in the private sector worldwide, very little is known of the organizations within which they practice. Such knowledge is important to help understand contexts of practice and how they influence the quality of services and patient outcomes. The purpose of this study was to: 1) describe characteristics of organizations where physiotherapists practice in the private sector, and 2) explore the existence of a taxonomy of organizational models. METHODS: This was a cross-sectional quantitative survey of 236 randomly-selected physiotherapists. Participants completed a purpose-designed questionnaire online or by telephone, covering organizational vision, resources, structures and practices. Organizational characteristics were analyzed descriptively, while organizational models were identified by multiple correspondence analyses. RESULTS: Most organizations were for-profit (93.2%), located in urban areas (91.5%), and within buildings containing multiple businesses/organizations (76.7%). The majority included multiple providers (89.8%) from diverse professions, mainly physiotherapy assistants (68.7%), massage therapists (67.3%) and osteopaths (50.2%). Four organizational models were identified: 1) solo practice, 2) middle-scale multiprovider, 3) large-scale multiprovider and 4) mixed. CONCLUSIONS: The results of this study provide a detailed description of the organizations where physiotherapists practice, and highlight the importance of human resources in differentiating organizational models. Further research examining the influences of these organizational characteristics and models on outcomes such as physiotherapists' professional practices and patient outcomes are needed

A Specific Primed Immune Response in Drosophila Is Dependent on Phagocytes

Drosophila melanogaster, like other invertebrates, relies solely on its innate immune response to fight invading microbes; by definition, innate immunity lacks adaptive characteristics. However, we show here that priming Drosophila with a sublethal dose of Streptococcus pneumoniae protects against an otherwise-lethal second challenge of S. pneumoniae. This protective effect exhibits coarse specificity for S. pneumoniae and persists for the life of the fly. Although not all microbial challenges induced this specific primed response, we find that a similar specific protection can be elicited by Beauveria bassiana, a natural fly pathogen. To characterize this primed response, we focused on S. pneumoniae–induced protection. The mechanism underlying this protective effect requires phagocytes and the Toll pathway. However, activation of the Toll pathway is not sufficient for priming-induced protection. This work contradicts the paradigm that insect immune responses cannot adapt and will promote the search for similar responses overlooked in organisms with an adaptive immune response

Managing healthcare budgets in times of austerity: the role of program budgeting and marginal analysis

Given limited resources, priority setting or choice making will remain a reality at all levels of publicly funded healthcare across countries for many years to come. The pressures may well be even more acute as the impact of the economic crisis of 2008 continues to play out but, even as economies begin to turn around, resources within healthcare will be limited, thus some form of rationing will be required. Over the last few decades, research on healthcare priority setting has focused on methods of implementation as well as on the development of approaches related to fairness and legitimacy and on more technical aspects of decision making including the use of multi-criteria decision analysis. Recently, research has led to better understanding of evaluating priority setting activity including defining ‘success’ and articulating key elements for high performance. This body of research, however, often goes untapped by those charged with making challenging decisions and as such, in line with prevailing public sector incentives, decisions are often reliant on historical allocation patterns and/or political negotiation. These archaic and ineffective approaches not only lead to poor decisions in terms of value for money but further do not reflect basic ethical conditions that can lead to fairness in the decision-making process. The purpose of this paper is to outline a comprehensive approach to priority setting and resource allocation that has been used in different contexts across countries. This will provide decision makers with a single point of access for a basic understanding of relevant tools when faced with having to make difficult decisions about what healthcare services to fund and what not to fund. The paper also addresses several key issues related to priority setting including how health technology assessments can be used, how performance can be improved at a practical level, and what ongoing resource management practice should look like. In terms of future research, one of the most important areas of priority setting that needs further attention is how best to engage public members