Field Theoretic Description of Ultrarelativistic Electron-Positron Plasmas

Ultrarelativistic electron-positron plasmas can be produced in high-intensity laser fields and play a role in various astrophysical situations. Their properties can be calculated using QED at finite temperature. Here we will use perturbative QED at finite temperature for calculating various important properties, such as the equation of state, dispersion relations of collective plasma modes of photons and electrons, Debye screening, damping rates, mean free paths, collision times, transport coefficients, and particle production rates, of ultrarelativistic electron-positron plasmas. In particular, we will focus on electron-positron plasmas produced with ultra-strong lasers.Comment: 13 pages, 7 figures, 1 table, published versio

Composite Interstage Structural Concept Down Select Process and Results

NASA's Advanced Composites Technologies (ACT) project evaluated several composite construction options for the Ares V Interstage to support the Constellation Program's goal of reducing the mass of vehicle dry structures. In Phase 1 of the project, eight candidate construction concepts were evaluated for the Ares V Interstage design. Trade studies were performed using finite element analyses to determine weight estimates for the construction concepts. An evaluation process was then used to down select the construction concepts down to two concepts for further consideration in Phase 2 of the project. In Phase 2 of the project, additional trade studies were performed using detailed finite element analyses of the Interstage and a final down select process was used to choose the recommended Interstage construction concept. The results of the study showed that a honeycomb sandwich design was the most favorable Interstage construction concept based on advantages in manufacturing cost. Details of the Phase 1 and Phase 2 trade studies and down select process with final results are presented in the paper

Chromodynamic Fluctuations in Quark-Gluon Plasma

Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.Comment: 19 pages, numerous but minor corrections, to appear in Phys. Rev.

Mentalising and social problem solving in adults with Asperger's syndrome

It is well established that autistic spectrum disorder is linked to difficulties with mentalising, but the ways in which this affects everyday behaviour is less well understood. This study explored the nature and extent of difficulties in everyday social functioning in adults with Asperger's syndrome (AS), since increased understanding can enhance the development of more effective intervention strategies. Methods Individuals with AS (n=21) were compared with healthy control participants (n=21) on three tests of social cognition: the Mentalistic Interpretation task, which assesses interpretation of sarcasm and actions; the Social Problem Fluency task, which assesses ability to generate problem solutions; and the Social Problem Resolution task, which assesses judgement in selecting problem solutions. Results Comprehension of both sarcastic remarks and actions was impaired in those with AS on the mentalistic interpretation task. Participants with AS showed difficulties in identifying the awkward elements of everyday social scenarios, and they were also impaired in generating problem solutions but not in judging alternative solutions on the social problem fluency and resolution tasks. Conclusions These tasks potentially provide a means of profiling strengths and weaknesses in social processing, which in turn has implications for informing clinical evaluation and training. © 2013 Taylor & Francis

Parton Equilibration in Relativistic Heavy Ion Collisions

We investigate the processes leading to phase-space equilibration of parton distributions in nuclear interactions at collider energies. We derive a set of rate equations describing the chemical equilibration of gluons and quarks including medium effects on the relevant QCD transport coefficients, and discuss their consequences for parton equilibration in heavy ion collisions.Comment: 18 pages, 6 Figures appended as uuencoded PostScript files, (no changes in the previously submitted manuscript), DUKE-TH-93-4

Integrating children's perspectives in policy-making to combat poverty and social exclusion experienced by single-parent families: a transnational comparative approach

This is the final report of a research project that addressed social exclusion and poverty as it relates to single parent families and their children in particular. The rising numbers of single parent families and children throughout the EU and the increased likelihood that these families will live in poverty and experience many different forms of social exclusion in their daily lives brings in sharp focus the need to address the issue as an urgent one in our efforts to eradicate poverty and social exclusion. The focus on the children of single parent families seeks to rectify a long-standing problem in our knowledge and understanding of single parent families and the social problems they face, namely, the fact that little, if anything, is known about how these children experience and understand their lives as members of these families. The research set out to contribute to policy development and the transnational exchange of best practice by adding a much-neglected dimension on single parent families. The project used a cross-national comparative qualitative research design and methods (Mangen 1999) which involved all partners in the design of each research phase including the analysis; partners were England, Cyprus and Greece

Quark Dispersion Relation and Dilepton Production in the Quark-Gluon Plasma

Under very general assumptions we show that the quark dispersion relation in the quark-gluon plasma is given by two collective branches, of which one has a minimum at a non-vanishing momentum. This general feature of the quark dispersion relation leads to structures (van Hove singularities, gaps) in the low mass dilepton production rate, which might provide a unique signature for the quark-gluon plasma formation in relativistic heavy ion collisions.Comment: 6 pages, Revtex, 2 PostScript figures, revised version to be published in Phys. Rev. Let

The use of remote sensing in an integrated approach for stress detection on the cultivated cranberry

Remote sensing is an attractive method for the detection and monitoring of crop stress. The feasibility of using remote sensing for the detection and monitoring of fungal diseases, insects, weeds, and non-infectious diseases affecting the cultivated cranberry (Vaccinium macrocarpon Ait.) is evaluated. A study on the fungal disease twig blight (Lophodermium spp.) was undertaken to illustrate the potential of using remote sensing. The important symptoms for remote sensing detection include leaf discoloration, reduced vigor, and biomass loss. Biomass loss and reduced vigor are the most important symptoms for cranberry stress detection, while leaf discolorations are usually inconspicuous and not widespread. Weeds, areas of dehydration, and general bog conditions can be easily detected at image scales of 1:12,000 and smaller. Fungus and insect damage can be monitored at smaller scales (1:6,000 and smaller); however, this information is more useful for regional or higher levels of management rather than for the individual grower. This is due to the likelihood of damage symptoms being the result of inefficient control practices rather than from the early establishment of stress. Many of the stresses have similar symptoms, making the identification of the stress agents difficult. Thus the timing of imagery acquisition is important and additional sources of information are necessary. Currently, remote sensing is best suited for inclusion in an integrated approach for a working stress detection and monitoring system. Study plots for the fungal disease twig blight (Lophodermium spp.) were selected in Long Beach, Washington. Aerial missions were conducted using color and color IR film with a 9" x 9" format (1:12000) and a 70mm format (1:3800). The progression of twig blight was monitored in study plots located in a commercial cranberry bog with ground photography employing 35mm color and color IR film. Comparisons of 11 different filters were made (5 IR filters, 3 red filters, and one green, yellow, and blue filter) with the best film/filter combination being a Wratten no. 12 (yellow) and color IR film. Aerial photograph interpretations were made from differences in image tone rather than leaf color changes. However, color differences are useful for identifying certain stress agents. Darker image tones had a positive correlation to Lophodermium spp. incidence, were independent of upright density, and had a negative correlation to upright density-revised. Upright density-revised is the total number of uprights minus the number of infected uprights. Healthy uprights grow above and cast a shadow over damaged uprights; therefore, upright density-revised is a better predictor of ground conditions important for remote sensing. Interpretation differences between filters could be attributed more to exposure differences than to anything else

Childhood adversity and later life prosocial behavior: A qualitative comparative study of Irish older adult survivors

Objective Although childhood adversity can have lasting effects into later life, positive adaptations have also been observed, including an increased tendency toward prosocial behavior. However, little is known about the link between childhood adversity and later life prosocial behavior, with a particular scarcity of research on intrafamilial childhood adversity. Therefore, this study aimed to examine older adult's experiences of childhood adversity and identify mechanisms linked to prosocial behavior. Two adversity contexts (intrafamilial and extrafamilial) were compared to explore individual, as well as broader cultural and contextual mechanisms linking childhood adversity and later life prosocial behavior. Method Semi-structured interviews (60–120 min) were conducted with N = 29 Irish (older) adult survivors of childhood adversity: n = 12 intrafamilial survivors (mean age: 58 years, range: 51–72), n = 17 institutional survivors (mean age: 61 years, range: 50–77). Interviews were analyzed using the framework analysis method, with reference to the conceptual model of altruism born of suffering. Results Five themes were identified on prosocial mechanisms, with three themes in both survivor groups (enhanced empathy, self-identity, amelioration), and two group-specific themes (compassion fatigue in intrafamilial survivors; denouncing detrimental social values in institutional survivors). Conclusion Results identified motivational processes and volitional factors linked to later life prosocial behavior. Connections to caring roles, (lack of) support, and social norms in childhood, as well as the need for a sense of purpose and meaning from the adversities in adulthood, highlight potential targets for psychotherapeutic intervention to promote prosocial responding and positive adaptation for childhood adversity survivors