Algebraic Rainich conditions for the tensor V

Algebraic conditions on the Ricci tensor in the Rainich-Misner-Wheeler unified field theory are known as the Rainich conditions. Penrose and more recently Bergqvist and Lankinen made an analogy from the Ricci tensor to the Bel-Robinson tensor $B_{\alpha\beta\mu\nu}$, a certain fourth rank tensor quadratic in the Weyl curvature, which also satisfies algebraic Rainich-like conditions. However, we found that not only does the tensor $B_{\alpha\beta\mu\nu}$ fulfill these conditions, but so also does our recently proposed tensor $V_{\alpha\beta\mu\nu}$, which has many of the desirable properties of $B_{\alpha\beta\mu\nu}$. For the quasilocal small sphere limit restriction, we found that there are only two fourth rank tensors $B_{\alpha\beta\mu\nu}$ and $V_{\alpha\beta\mu\nu}$ which form a basis for good energy expressions. Both of them have the completely trace free and causal properties, these two form necessary and sufficient conditions. Surprisingly either completely traceless or causal is enough to fulfill the algebraic Rainich conditions. Furthermore, relaxing the quasilocal restriction and considering the general fourth rank tensor, we found two remarkable results: (i) without any symmetry requirement, the algebraic Rainich conditions only require totally trace free; (ii) with a symmetry requirement, we recovered the same result as in the quasilocal small sphere limit.Comment: 17 page

Characteristics of inhomogeneous jets in confined swirling air flows

An experimental program to study the characteristics of inhomogeneous jets in confined swirling flows to obtain detailed and accurate data for the evaluation and improvement of turbulent transport modeling for combustor flows is discussed. The work was also motivated by the need to investigate and quantify the influence of confinement and swirl on the characteristics of inhomogeneous jets. The flow facility was constructed in a simple way which allows easy interchange of different swirlers and the freedom to vary the jet Reynolds number. The velocity measurements were taken with a one color, one component DISA Model 55L laser-Doppler anemometer employing the forward scatter mode. Standard statistical methods are used to evaluate the various moments of the signals to give the flow characteristics. The present work was directed at the understanding of the velocity field. Therefore, only velocity and turbulence data of the axial and circumferential components are reported for inhomogeneous jets in confined swirling air flows

Comparison of laser performance for diode-pumped Tm:YLF of various doping concentrations

Single-end-pumped laser performance of 2, 4, and 6at.% Tm-doped YLF rods is reported. For the pumping configuration employed, crystal fracture was observed to occur for a thermal load per unit absorption length of ~13W/cm. The 2at.% Tm-doped crystal was found to have a quantum yield of ~90% of that of 4at.% Tm. However, due to a lower thermal loading density, the maximum possible incident pump power is predicted to be >60% higher, hence offering a greater output power per rod for the lower doping concentration. Power scaling considerations are discussed with reference to cross-relaxation, upconversion, and thermal loading of the host crystal

Modelling psychological responses to the great East Japan earthquake and nuclear incident

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited - Copyright @ 2012 Goodwin et al.This article has been made available through the Brunel Open Access Publishing Fund.The Great East Japan (Tōhoku/Kanto) earthquake of March 2011was followed by a major tsunami and nuclear incident. Several previous studies have suggested a number of psychological responses to such disasters. However, few previous studies have modelled individual differences in the risk perceptions of major events, or the implications of these perceptions for relevant behaviours. We conducted a survey specifically examining responses to the Great Japan earthquake and nuclear incident, with data collected 11-13 weeks following these events. 844 young respondents completed a questionnaire in three regions of Japan; Miyagi (close to the earthquake and leaking nuclear plants), Tokyo/Chiba (approximately 220 km from the nuclear plants), and Western Japan (Yamaguchi and Nagasaki, some 1000 km from the plants). Results indicated significant regional differences in risk perception, with greater concern over earthquake risks in Tokyo than in Miyagi or Western Japan. Structural equation analyses showed that shared normative concerns about earthquake and nuclear risks, conservation values, lack of trust in governmental advice about the nuclear hazard, and poor personal control over the nuclear incident were positively correlated with perceived earthquake and nuclear risks. These risk perceptions further predicted specific outcomes (e.g. modifying homes, avoiding going outside, contemplating leaving Japan). The strength and significance of these pathways varied by region. Mental health and practical implications of these findings are discussed in the light of the continuing uncertainties in Japan following the March 2011 events

Exploring knowledge exchange: a useful framework for practice and policy

Knowledge translation is underpinned by a dynamic and social knowledge exchange process but there are few descriptions of how this unfolds in practice settings. This has hampered attempts to produce realistic and useful models to help policymakers and researchers understand how knowledge exchange works. This paper reports the results of research which investigated the nature of knowledge exchange. We aimed to understand whether dynamic and fluid definitions of knowledge exchange are valid and to produce a realistic, descriptive framework of knowledge exchange. Our research was informed by a realist approach. We embedded a knowledge broker within three service delivery teams across a large mental health organisation, each of whom was grappling with specific challenges. The knowledge broker participated in the team's problem-solving process and collected observational fieldnotes. We also interviewed the team members. Observational and interview data were analysed quantitatively and qualitatively in order to determine and describe the nature of the knowledge exchange process in more detail. This enabled us to refine our conceptual framework of knowledge exchange. We found that knowledge exchange can be understood as a dynamic and fluid process which incorporates distinct forms of knowledge from multiple sources. Quantitative analysis illustrated that five broadly-defined components of knowledge exchange (problem, context, knowledge, activities, use) can all be in play at any one time and do not occur in a set order. Qualitative analysis revealed a number of distinct themes which better described the nature of knowledge exchange. By shedding light on the nature of knowledge exchange, our findings problematise some of the linear, technicist approaches to knowledge translation. The revised model of knowledge exchange which we propose here could therefore help to reorient thinking about knowledge exchange and act as a starting point for further exploration and evaluation of the knowledge exchange process

Integrating fish resources to agro-ecosystem analyses

In October 2005, a consortium of partners led by the International Water Management Institute (IWMI) proposed a project aimed at integrating fish resources management in agricultural management in the Tonle Sap area. This 2-years project assistance was accepted for funding by the Challenge Program on Water and Food and started in January 2008. The overall goal of this project is to improve allocation and use of water in combined farming and fishing systems in order to enhance food security of rural communities and water productivity. The general objectives of the Fisheries component are: 1) to contribute to the review of existing fisheries and aquaculture information, assessment and data collection systems and existing databases from a fisheries perspective 2) to determine key questions that could be asked at the commune level that would enable the identification of fisheries issues for different agroecosystem zones. These would include both threats and potential threats to fisheries based on key ecological variables and opportunities that fisheries and aquaculture could represent in local livelihoods.Research, Lake fisheries, Agropisciculture, Ecosystems, Analysis, Cambodia, Tonle Sap L.,

Behavior of turbulent gas jets in an axisymmetric confinement

The understanding of the mixing of confined turbulent jets of different densities with air is of great importance to many industrial applications, such as gas turbine and Ramjet combustors. Although there have been numerous studies on the characteristics of free gas jets, little is known of the behavior of gas jets in a confinement. The jet, with a diameter of 8.73 mm, is aligned concentrically in a tube of 125 mm diameter, thus giving a confinement ratio of approximately 205. The arrangement forms part of the test section of an open-jet wind tunnel. Experiments are carried out with carbon dioxide, air and helium/air jets at different jet velocities. Mean velocity and turbulence measurements are made with a one-color, one-component laser Doppler velocimeter operating in the forward scatter mode. Measurements show that the jets are highly dissipative. Consequently, equilibrium jet characteristics similar to those found in free air jets are observed in the first two diameters downstream of the jet. These results are independent of the fluid densities and velocities. Decay of the jet, on the other hand, is a function of both the jet fluid density and momentum. In all the cases studied, the jet is found to be completely dissipated in approximately 30 jet diameters, thus giving rise to a uniform flow with a very high but constant turbulence field across the confinement

Gravitational energy from a combination of a tetrad expression and Einstein's pseudotensor

The energy-momentum for a gravitating system can be considered by the tetard teleparalle gauge current in orthonormal frames. Whereas the Einstein pseudotensor used holonomic frames. Tetrad expression itself gives a better result for gravitational energy than Einstein's. Inspired by an idea of Deser, we found a gravitational energy expression which enjoys the positive energy property by combining the tetrad expression and the Einstein pseudotensor, i.e., the connection coefficient has a form appropriate to a suitable intermediate between orthonormal and holonomic frames.Comment: 5 page

Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 12^{12}C+208^{208}Pb System at Near-Coulomb-Barrier Energies by using a Folding Potential

Simultaneous $\chi^{2}$ analyses are performed for elastic scattering and fusion cross section data for the $^{12}$C+$^{208}$Pb system at near-Coulomb-barrier energies by using the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and also that both DR and fusion parts of the polarization potential determined from the $\chi^{2}$ analyses satisfy separately the dispersion relation. Furthermore, it is shown that the imaginary parts of both DR and fusion potentials at the strong absorption radius change very rapidly, which results in a typical threshold anomaly in the total imaginary potential as observed with tightly bound projectiles such as $\alpha$-particle and $^{16}$O.Comment: 26 pages, 7 figures, submitted to Physical Review