Light bullets in quadratic media with normal dispersion at the second harmonic

Stable two- and three-dimensional spatiotemporal solitons (STSs) in second-harmonic-generating media are found in the case of normal dispersion at the second harmonic (SH). This result, surprising from the theoretical viewpoint, opens a way for experimental realization of STSs. An analytical estimate for the existence of STSs is derived, and full results, including a complete stability diagram, are obtained in a numerical form. STSs withstand not only the normal SH dispersion, but also finite walk-off between the harmonics, and readily self-trap from a Gaussian pulse launched at the fundamental frequency.Comment: 4 pages, 5 figures, accepted to Phys. Rev. Let

Three-dimensional spatiotemporal optical solitons in nonlocal nonlinear media

We demonstrate the existence of stable three-dimensional spatiotemporal solitons (STSs) in media with a nonlocal cubic nonlinearity. Fundamental (nonspinning) STSs forming one-parameter families are stable if their propagation constant exceeds a certain critical value, that is inversely proportional to the range of nonlocality of nonlinear response. All spinning three-dimensional STSs are found to be unstable.Comment: 14 pages, 6 figures, accepted to PRE, Rapid Communication

Applying tropos to socio-technical system design and runtime configuration

Recent trends in Software Engineering have introduced the importance of reconsidering the traditional idea of software design as a socio-tecnical problem, where human agents are integral part of the system along with hardware and software components. Design and runtime support for Socio-Technical Systems (STSs) requires appropriate modeling techniques and non-traditional infrastructures. Agent-oriented software methodologies are natural solutions to the development of STSs, both humans and technical components are conceptualized and analyzed as part of the same system. In this paper, we illustrate a number of Tropos features that we believe fundamental to support the development and runtime reconfiguration of STSs. Particularly, we focus on two critical design issues: risk analysis and location variability. We show how they are integrated and used into a planning-based approach to support the designer in evaluating and choosing the best design alternative. Finally, we present a generic framework to develop self-reconfigurable STSs

Vicarious traumatic exposure among New Zealand health professionals : An exploration of coping strategies and vicarious posttraumatic growth : a thesis presented in partial fulfilment of the degree of Doctor of Clinical Psychology at Massey University, Wellington, New Zealand

The negative effects of working with trauma survivors have been well documented. This thesis provides an exploration of the less researched positive psychological effects of such work, termed vicarious posttraumatic growth (VPTG). Specifically, the research aimed to investigate New Zealand health professionals’ use of coping strategies (social support, self-care, and humour) following vicarious traumatic exposure, how these coping strategies influenced the psychological outcome of vicarious traumatic exposure, and how VPTG related to secondary traumatic stress (STS). It was also of interest whether all types of health professionals coped with, and psychologically reacted to, vicarious traumatic exposure in the same way, or if there were differences between professions. A total of 365 health professionals participated in the current research by completing a quantitative online survey. The final sample consisted of 103 social workers, 76 nurses, 72 counsellors, 70 psychologists, and 44 medical doctors. Humour, self-care, and peer social support were found to be positive predictors of VPTG, while self-care and social support from family and friends were negative predictors of STS. In addition, peer support was found to be a partial mediator of the relationship between vicarious traumatic exposure and STS. Social workers were found to have the highest levels of STS and VPTG, while psychologists were found to have the lowest levels. Regarding coping, generally psychologists and counsellors were found to engage in the highest levels of coping strategies, while nurses and doctors reported the lowest levels. However, the opposite pattern was found for peer support; nurses reported a significantly higher level of peer support than psychologists. Finally, a curvilinear relationship was found between STS and VPTG; moderate levels of STS were associated with the highest levels of VPTG. However, this was only the case among psychologists; among all other professions STS did not correlate with or predict VPTG. Implications of these results are discussed. Investigation into the relationship between humour and VPTG, exploration of coping strategies as mediators, and the systematic investigation of differences between different types of health professionals represent current gaps in the literature. In addition, exploration of the relationship between VPTG and STS represents an under-researched area with mixed results. Therefore, the current research is an important contribution to the current body of literature. It is envisaged that conclusions drawn from this research will have beneficial implications for health care professionals and the organisations they work within