Topical Issues for Particle Acceleration Mechanisms in Astrophysical Shocks

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of the key issues for shock acceleration theory that require resolution in order to propel our understanding of particle energization in astrophysical environments. These include magnetic field amplification in shock ramps, the non-linear hydrodynamic interplay between thermal ions and their extremely energetic counterparts possessing ultrarelativistic energies, and the ability to inject and accelerate electrons in both non-relativistic and relativistic shocks. Recent observational developments that impact these issues are summarized. While these topics are currently being probed by astrophysicists using numerical simulations, they are also ripe for investigation in laboratory experiments, which potentially can provide valuable insights into the physics of cosmic shocks.Comment: 13 pages, no figures. Invited review, accepted for publication in Astrophysics and Space Science, as part of the HEDLA 2006 conference proceeding

LeverAge: a European network to leverage the multi-age workforce

Bringing together 150+ scholars and practitioners from 50+ countries, and funded by the European Commission, COST Action LeverAge (https:// www.cost.eu/actions/CA22120/) is the first network-building project of its kind in the work and organizational psychology and human resource management (WOP/HRM) aspects of work and aging. Focused on the aging workforce, the Action aims to foster interdisciplinary and multinational scientific excellence and the translation of science to practical and societal impact across 4 years. Based on a research synthesis, we identify five broad research directions for work and aging science including work and organizational practices for a multi-age workforce, successful aging at work, the integration of age-diverse workers and knowledge transfer, aging and technology at work, and career development in later life and retirement. We provide key research questions to guide scientific inquiry along these five research directions alongside best practice recommendations to expand scholarly impact in WOP/HRM

The neutron imaging system fielded at the National Ignition Facility

We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n′) reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system is presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system is presented. We also discuss future improvements to the system hardware

Comparing neutron and X-ray images from NIF implosions

Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield

`He hath the French pox` : stigma, social value and social exclusion

Goods and resources are finite, and social forces heavily pattern their distribution. One of the principal mechanisms for shaping the distribution of resources is by regulating entitlement to community membership itself. By restricting groups\u27 membership of community, so access to social goods and resources diminishes, which in turn has a negative impact on the health and wellbeing of the excluded groups. It is argued here that community membership is determined on the basis of the perceived social value of groups and individuals and stigmatisation is the marking of individuals and groups who are \u27unworthy\u27 of social investment. Using the notion of reciprocity we show how groups may be stigmatised and socially excluded as a mechanism for protecting limited social resources from exploitation. This perspective provides an empirically testable framework for the understanding of stigma and social exclusion that goes beyond the largely descriptive work that currently populates the field. We illustrate the process of stigmatisation and social exclusion and discuss how this suggests new styles of intervention, as well as new directions for research.<br /

Comparing neutron and X-ray images from NIF implosions

Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield