Electron transport & ion acoustic dynamics in laser-produced plasmas

In this thesis laser-plasma processes are studied at transport and ion time scales. In order to study these processes the particle-in-cell code QNPIC with one spatial dimension and three dimensions in velocity space was developed. Collisional effects are included by a Monte Carlo procedure, and an electric field solver based on the quasineutrality condition has been implemented. This allows long time scale simulations without having to resolve the electron plasma frequency. Collisional heating of the electrons in the laser electric field is one of the major restrictions on the time step in particle-in-cell codes. We have developed a collisional heating procedure that is based on a Langevin equation. It utilizes a Fokker-Planck equation that describes heating time averaged over the laser frequency. This procedure, in conjunction with the fast field solver and procedures to represent collisions, allows simulation of long time scale in laser-plasma interactions without the need to resolve the short time scales to ensure numerical stability and suppress numerical artifacts. We have studied in detail homogeneously heated plasmas and the effects of electron-electron collisions and collisional heating on the electron distribution function. We have suggested a nonlocal, nonlinear heat transport model based on a earlier self consistent nonlocal transport theory that is formally restricted to small (linearized) temperature perturbations. Our model extends this model to the case of finite temperature perturbations. The model is tested successfully in simulations of hot spot relaxation of an initial temperature distribution that corresponds to the instantaneous release of heat into a spatially Gaussian temperature profile and Maxwellian velocity distributions of the electrons. In simulations of collisionally heated hot spots we qualitatively describe the effects of non-Maxwellian velocity distributions on the heat flux and the change of the distribution function due to transport in nonheated regions. For the representation of ion dynamics in QNPIC we have conducted studies of the two stream instability with counterstreaming electrons and ions. Predicted growth rates of ion sound waves are recovered and we find it possible to study anomalous heating and resistivity in ID ion sound turbulence. In laser plasmas ion sound turbulence due to the return current instability is thought to be one of the factors in the reduction of heat flux from hot spots. Since this instability is of kinetic nature it cannot be reproduced by hydrodynamic simulations. Our preliminary results of the return current instability in electron temperature gradients using QNPIC indicate the feasibility of particle codes to treat this problem. For the analytic description of ion dynamics we have developed kinetic closures of the ion fluid equations that allow a single representation of the dynamics over all regimes of collisionalities. We employ a Chapman-Enskog like procedure for the closure and use a 21-moment representation for the collisional terms which ensure that the classical collisional limit of the transport coefficients is recovered. Ion sound like waves, transverse to a nonlinear perturbation, are investigated in a cold ion fluid model. We demonstrated the applicability of a stability analysis from the study of solitons to an ion sheath and a double layer potential. In case of the double layer we find transverse ion oscillations with phase velocities approaching zero

Electron kinetic effects in the nonlinear evolution of a driven ion-acoustic wave

The electron kinetic effects are shown to play an important role in the nonlinear evolution of a driven ion-acoustic wave. The numerical simulation results obtained (i) with a hybrid code, in which the electrons behave as a fluid and the ions are described along the particle-in-cell (PIC) method, are compared with those obtained (ii) with a full-PIC code, in which the kinetic effects on both species are retained. The electron kinetic effects interplay with the usual fluid-type nonlinearity to give rise to a broadband spectrum of ion-acoustic waves saturated at a low level, even in the case of a strong excitation. This low asymptotic level might solve the long-standing problem of the small stimulated Brillouin scattering reflectivity observed in laser-plasma interaction experiments

Advance Care Planning for Adults With CKD: A Systematic Integrative Review

Author version made avilable in accordance with the publisher's policy. © 2014, the National Kindney Foundation, inc. 
Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/Background Recent clinical practice guidelines have highlighted the importance of advance care planning (ACP) for improving end-of-life care for people with chronic kidney disease (CKD). Study Design We conducted a systematic integrative review of the literature to inform future ACP practice and research in CKD, searching electronic databases in April 2013. Synthesis used narrative methods. Setting & Population We focused on adults with a primary diagnosis of CKD in any setting. Selection Criteria for Studies We included studies of any design, quantitative or qualitative.. Interventions ACP was defined as any formal means taken to ensure health professionals and family members are aware of patients’ wishes for care in the event they become too unwell to speak for themselves. Outcomes Measures of all kinds were considered to be of interest. Results Fifty-five articles met criteria reporting on 51 discrete samples. All patient samples included people with Stage 5 CKD; two also included patients with Stage 4. Seven interventions were tested; all were narrowly focused and none was evaluated by comparing wishes for end-of-life care with care received. One intervention demonstrated effects on patient/family outcomes in the form of improved wellbeing and anxiety following sessions with a peer mentor. Insights from qualitative studies that have not been emphasised in interventions include the importance of instilling patient confidence that their advance directives will be enacted and discussing decisions about (dis)continuing dialysis separately from ‘aggressive’ life-sustaining treatments (e.g. ventilation). Limitations Whilst quantitative and qualitative findings were integrated according to best practice, methods for this are in their infancy. Conclusions Research on ACP in patients with CKD is limited, especially regarding intervention studies. Interventions in CKD should attend to barriers and facilitators at the levels of patient, caregiver, health professional and system. Intervention studies should measure impact on compliance with patient wishes for end-of-life care. Index words Chronic kidney disease, Renal failure, Advance care planning, Advance directives, Decision-makin

A reference linkage map for Eucalyptus

Background: Genetic linkage maps are invaluable resources in plant research. They provide a key tool for many genetic applications including: mapping quantitative trait loci (QTL); comparative mapping; identifying unlinked (i.e. independent) DNA markers for fingerprinting, population genetics and phylogenetics; assisting genome sequence assembly; relating physical and recombination distances along the genome and map-based cloning of genes. Eucalypts are the dominant tree species in most Australian ecosystems and of economic importance globally as plantation trees. The genome sequence of E. grandis has recently been released providing unprecedented opportunities for genetic and genomic research in the genus. A robust reference linkage map containing sequence-based molecular markers is needed to capitalise on this resource. Several high density linkage maps have recently been constructed for the main commercial forestry species in the genus (E. grandis, E. urophylla and E. globulus) using sequenced Diversity Arrays Technology (DArT) and microsatellite markers. To provide a single reference linkage map for eucalypts a composite map was produced through the integration of data from seven independent mapping experiments (1950 individuals) using a marker-merging method. Results: The composite map totalled 1107 cM and contained 4101 markers; comprising 3880 DArT, 213 microsatellite and eight candidate genes. Eighty-one DArT markers were mapped to two or more linkage groups, resulting in the 4101 markers being mapped to 4191 map positions. Approximately 13% of DArT markers mapped to identical map positions, thus the composite map contained 3634 unique loci at an average interval of 0.31 cM. Conclusion: The composite map represents the most saturated linkage map yet produced in Eucalyptus. As the majority of DArT markers contained on the map have been sequenced, the map provides a direct link to the E. grandis genome sequence and will serve as an important reference for progressing eucalypt research

Complex Physical, Biophysical and Econophysical Systems

This book arose from a conference organized under the auspices of the Australian Research Council's Complex Open Systems Research Network (which has become the most prominent for complex systems in the world — just Google “complex systems network”), the ANU Centre for Complex Systems, and the Asia-Pacific Center for Theoretical Physics. The book is unique in the scope of its coverage of applications of complex systems science: Extraterrestrial — astrophysical, solar and space plasmas; Earth System — climate, ecosystems; Human systems — brain dynamics, social networks, financial statistics, advanced technologies. It also presents up-to-date discussions of new theoretical approaches, in particular those based on entropy and entropy production maximization, a field still under development but with much promise for providing a much-needed unifying principle for complex systems science. The authors are at the forefront of their fields, and organized their chapters to effectively bring out common features of complex systems. A comprehensive and common lexicon of keywords has been used to unify indexing, thus making the book an invaluable introduction to anyone seeking an overview of complex systems science

Transverse stability of strongly nonlinear ion acoustic modes

The transverse stability of strongly nonlinear ion-acoustic structures, described by the general Sagdeev potential, is investigated. It is shown, that the multi-scale stability analysis by [Sov. Phys. Dokl. 15 (1970) 539] for solitary waves, described b