Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1

Current mass-loss rate estimates imply that main sequence winds are not sufficient to strip away the H-rich envelope to yield Wolf-Rayet (WR) stars. The rich transitional population of Westerlund 1 (Wd 1) provides an ideal laboratory to observe mass-loss processes throughout the transitional phase of stellar evolution. An analysis of deep radio continuum observations of Wd 1 is presented. We detect 18 cluster members. The radio properties of the sample are diverse, with thermal, non-thermal and composite thermal/non-thermal sources present. Mass-loss rates are ~10^{-5} solar mass/year across all spectral types, insufficient to form WRs during a massive star lifetime, and the stars must undergo a period of enhanced mass loss. The sgB[e] star W9 may provide an example, with a mass-loss rate an order of magnitude higher than the other cluster members, and an extended nebula of density ~3 times the current wind. This structure is reminiscent of luminous blue variables, and one with evidence of two eras of high, possibly eruptive, mass loss. Three OB supergiants are detected, implying unusually dense winds. They also may have composite spectra, suggesting binarity. Spatially resolved nebulae are associated with three of the four RSGs and three of the six YHGs in the cluster, which are due to quiescent mass loss rather than outbursts. For some of the cool star winds, the ionizing source may be a companion star though the cluster radiation density is sufficiently high to provide the necessary ionizing radiation. Five WR stars are detected with composite spectra, interpreted as arising in colliding-wind binaries.Comment: 15 pages, 6 figures. Accepted for publication in Astronomy and Astrophysic

Radio emission from the massive stars in Westerlund 1

The diverse massive stellar population in the young massive clusterWesterlund 1 (Wd 1) provides an ideal laboratory to observe and constrain mass-loss processes throughout the transitional phase of massive star evolution. A set of high sensitivity radio observations of Wd 1 leads to the detection of 18 cluster members, a sample dominated by cool hypergiants, but with detections among hotter OB supergiants and WR stars. Here the diverse radio properties of the detected sample are briefly described. The mass-loss rates of the detected objects are surprisingly similar across the whole transitional phase of massive star evolution, at ~ 10-5 Mo yr−1. Such a rate is insufficient to strip away the H-rich mantle in a massive star lifetime, unless the stars go through a period of enhanced mass-loss. The radio luminous star W9 provides an example of such an object, with evidence for two eras of mass-loss with rates of ~ 10−4 Mo yr−1

The unavoidable costs of ethnicity : a review of evidence on health costs

This report was commissioned by the Advisory Committee on Resource Allocation (ACRA), and prepared by the Centre for Health Services Studies (CHESS) and the Centre for Research in Ethnic Relations (CRER) at the University of Warwick. The NHS Executive does not necessarily assent to the factual accuracy of the report, nor necessarily share the opinions and recommendations of the authors. The study reviews the evidence concerning the degree to which the presence of populations of minority ethnic origin was associated with ‘unavoidable additional costs’ in health service delivery. While local health authorities retail full autonomy in their use of funds allocated to them under the Hospital and Community Health Services formula, the size of that budget is governed by a set of weightings applied to their population, to allow for factors known to influence levels of need, and the costs of providing services. The study began by considering the definitions used in describing ‘ethnicity’ and ethnic groups in relevant medical and social policy literature. It is clear that no fixed set of terms can be adopted, and that flexibility is required to respond to social changes. The terms used in the 1991 Census, with additions to allow for local and contemporary developments, provide a suitable baseline but require additional information on religion language and migration history for clinical and health service delivery planning. There have been notable developments in health service strategy to meet the needs of black and minority ethnic groups which have been encouraged by good practice guidelines and local initiatives. Together with research into epidemiology and ethnic monitoring of services, these have enlarged understanding of the impact of diversity. A conceptual model is developed which explores the potential for such diversity to lead to variations in the cost of providing health services to a multi-ethnic population. The research team reviewed the existing published evidence relating to ethnic health and disease treatment in medical, social science, academic and practitioner literature, using conventional techniques. Additional evidence was located through trawls of ‘grey’ literature in specialist collections, and through contacting all English health districts with a request for information. A number of authorities and trusts provided written and oral evidence, and a bibliography of key materials is provided. Key issues considered include the need for and use of, interpreter and translation services, the incidence of ‘ethnically-specific’ disease, and variations in the prevalence and cost of treating ‘common’ conditions in minority ethnic populations. Sources of variation are discussed, and a ‘scoping’ approach adopted to explore the extent to which these variations could be adequately modelled. It is clear that while some additional costs can be identified, and seen to be unavoidable, there are other areas where the presence of minority populations may lead to lessened pressures on budgets, or where provision of ‘ethnic-specific’ facilities may be alternative to existing needs. The literature provides a range of estimates which can be used in a modelling exercise, but is deficient in many respects, particularly in terms of precise costs associated with procedure and conditions, or in associating precise and consistent categories of ethnic group with epidemiological and operational service provision data. Certain other activities require funding to set them up, and may not be directly related to population size. There is considerable variation in the approaches adopted by different health authorities, and many services are provided by agencies not funded by NHS budgets. The study was completed before the announcement of proposed changes in health service commissioning which may have other implications for ethnic diversity. The presence of minorities is associated with the need to provide additional services in respect of interpreting and translation, and the media of communication. In order to achieve clinical effectiveness, a range of advocacy support facilities or alternative models of provision seem to be desirable. Ethnic diversity requires adaptation and additional evidence in order to inform processes of consultation and commissioning. Minority populations do create demands for certain additional specific clinical services not required by the bulk of the majority population: it is not yet clear to what extent the reverse can be stated since research on ‘under-use’ is less well developed. Some variations in levels of need, particularly those relating to established clinical difference in susceptibility or deprivation, are already incorporated in funding formulae although it is not clear how far the indicators adequately reflect these factors. Costs are not necessarily simply related to the size of minority populations. The provision of services to meet minority needs is not always a reflection of their presence, but has frequently depended upon the provision of additional specific funds. There is a consensus that the NHS research and development strategy should accept the need for more work to establish the actual levels of need and usage of service by ethnic minority groups, and that effort should be made to use and improve the growing collection of relevant information through ethnic monitoring activities. A variety of modelling techniques are suggested, and can be shown to have the potential to provide practical guidance to future policy in the field. Current data availability at a national or regional scale is inadequate to provide estimates of the ‘additional costs of ethnicity’ but locally collected data and the existence of relevant policy initiatives suggest that a focused study in selected districts would provide sufficiently robust information to provide reliable estimates. The review has demonstrated that there are costs associated with the presence of minority ethnic groups in the population which can be shown to be unavoidable and additional, but that others are either ‘desirable’ or ‘alternative’. It would be wrong to assume that all cost pressures of this nature are in the same direction. Our study has drawn attention to deficiencies in data collection and budgeting which may hinder investigation of the effectiveness of the service in general. The process of drawing attention to ethnic minority needs itself leads to developments in services which are functional and desirable for the majority population

Breathing oscillations of a trapped impurity in a Bose gas

Motivated by a recent experiment [J. Catani et al., arXiv:1106.0828v1 preprint, 2011], we study breathing oscillations in the width of a harmonically trapped impurity interacting with a separately trapped Bose gas. We provide an intuitive physical picture of such dynamics at zero temperature, using a time-dependent variational approach. In the Gross-Pitaevskii regime we obtain breathing oscillations whose amplitudes are suppressed by self trapping, due to interactions with the Bose gas. Introducing phonons in the Bose gas leads to the damping of breathing oscillations and non-Markovian dynamics of the width of the impurity, the degree of which can be engineered through controllable parameters. Our results reproduce the main features of the impurity dynamics observed by Catani et al. despite experimental thermal effects, and are supported by simulations of the system in the Gross-Pitaevskii regime. Moreover, we predict novel effects at lower temperatures due to self-trapping and the inhomogeneity of the trapped Bose gas.Comment: 7 pages, 3 figure

Blackbody radiation shift in a 43Ca+ ion optical frequency standard

Motivated by the prospect of an optical frequency standard based on 43Ca+, we calculate the blackbody radiation (BBR) shift of the 4s_1/2-3d_5/2 clock transition, which is a major component of the uncertainty budget. The calculations are based on the relativistic all-order single-double method where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. Additional calculations are conducted for the dominant contributions in order to evaluate some omitted high-order corrections and estimate the uncertainties of the final results. The BBR shift obtained for this transition is 0.38(1) Hz. The tensor polarizability of the 3d_5/2 level is also calculated and its uncertainty is evaluated as well. Our results are compared with other calculations.Comment: 4 page

Noise Impacts from Professional Dog Grooming Forced-Air Dryers

This study was designed to measure the sound output of four commonly used brands of forced-air dryers used by dog groomers in the United States. Many dog groomers have questions about the effect of this exposure on their hearing, as well as on the hearing of the dogs that are being groomed. Readings taken from each dryer at 1 meter (the likely distance of the dryer from the groomer and the dog) showed average levels ranging from 105.5 to 108.3 dB SPL or 94.8 to 108.0 dBA. Using the 90 dBA criterion required by the US Occupational Safety and Health Administration, dog groomers/bathers are at risk if exposure to the lowest intensity dryer (94.8 dBA) exceeds 4 hours per day. If the more stringent 85 dBA criterion and 3 dB tradeoff is applied, less than one hour of exposure is permissible in an 8 hour day. Cautions are recommended for any persons exposed to noise from forced-air dryers

Disturbance Detection, Identification, and Recovery by Gait Transition in Legged Robots

We present a framework for detecting, identifying, and recovering within stride from faults and other leg contact disturbances encountered by a walking hexapedal robot. Detection is achieved by means of a software contactevent sensor with no additional sensing hardware beyond the commercial actuators’ standard shaft encoders. A simple finite state machine identifies disturbances as due either to an expected ground contact, a missing ground contact indicating leg fault, or an unexpected “wall” contact. Recovery proceeds as necessary by means of a recently developed topological gait transition coordinator. We demonstrate the efficacy of this system by presenting preliminary data arising from two reactive behaviors — wall avoidance and leg-break recovery. We believe that extensions of this framework will enable reactive behaviors allowing the robot to function with guarded autonomy under widely varying terrain and self-health conditions

Standing Self-Manipulation for a Legged Robot

On challenging, uneven terrain a legged robot’s open loop posture will almost inevitably be inefficient, due to uncoordinated support of gravitational loads with coupled internal torques. By reasoning about certain structural properties governing the infinitesimal kinematics of the closed chains arising from a typical stance, we have developed a computationally trivial self-manipulation behavior that can minimize both internal and external torques absent any terrain information. The key to this behavior is a change of basis in torque space that approximates the partially decoupled nature of the two types of disturbances. The new coordinates reveal how to use actuator current measurements as proprioceptive sensors for the approximate gradients of both the internal and external task potential fields, without recourse to further modeling. The behavior is derived using a manipulation framework informed by the dual relationship between a legged robot and a multifingered hand. We implement the reactive posture controller resulting from simple online descent along these proprioceptively sensed gradients on the X-RHex robot to document the significant savings in standing power. For more information: Kod*La

Magic wavelengths for the np-ns transitions in alkali-metal atoms

Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np_1/2, np_3/2 states and a large number of excited states are considered in these calculations and their accuracy is evaluated. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali-metal atoms. We find magic wavelengths in alkali-metal atoms for which the ns and np_1/2 and np_3/2 atomic levels have the same ac Stark shifts, which facilitates state-insensitive optical cooling and trapping.Comment: 12 pages, 8 figure

Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India

Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure–temperature–time (P–T–t) evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagioclase, magnetite, ilmenite, spinel and melt is consistent with peak metamorphic pressures of 6–8 kbar and temperatures in excess of 900 °C. Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 °C. SHRIMP U–Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages. New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation, and the minimum age of the metamorphic peak, to around 560 Ma. The data suggest two stages of monazite growth. The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite. Relatively REE-depleted rims, which have a pronounced negative europium anomaly, grew during melt crystallisation along the retrograde path at around 535 Ma. Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer, supporting a long-lived high-grade metamorphic history. The metamorphic conditions, timing and duration of the implied clockwise P–T–t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent