An unconfined, large-volume hydrogen/air explosion

Cause and results of the autoignition of 283 cubic meters of hydrogen gas, of which only about 10 percent exploded, are given. Results indicate that autoignition produces an explosion which could be described as a deflagration of explosive velocity, with a shock wave of sonic velocity and minor damage potential

Nonlinear Hodge maps

We consider maps between Riemannian manifolds in which the map is a stationary point of the nonlinear Hodge energy. The variational equations of this functional form a quasilinear, nondiagonal, nonuniformly elliptic system which models certain kinds of compressible flow. Conditions are found under which singular sets of prescribed dimension cannot occur. Various degrees of smoothness are proven for the sonic limit, high-dimensional flow, and flow having nonzero vorticity. The gradient flow of solutions is estimated. Implications for other quasilinear field theories are suggested.Comment: Slightly modified and updated version; tcilatex, 32 page

Harmonic fields on the extended projective disc and a problem in optics

The Hodge equations for 1-forms are studied on Beltrami's projective disc model for hyperbolic space. Ideal points lying beyond projective infinity arise naturally in both the geometric and analytic arguments. An existence theorem for weakly harmonic 1-fields, changing type on the unit circle, is derived under Dirichlet conditions imposed on the non-characteristic portion of the boundary. A similar system arises in the analysis of wave motion near a caustic. A class of elliptic-hyperbolic boundary-value problems is formulated for those equations as well. For both classes of boundary-value problems, an arbitrarily small lower-order perturbation of the equations is shown to yield solutions which are strong in the sense of Friedrichs.Comment: 30 pages; Section 3.3 has been revise

Perception of Technological Risks: The Effect of Confrontation

The response of the individual to potentially threatening situations is based upon his perception of the hazard involved. In this pilot study, 148 subjects were asked to quantitatively rank the hazard they felt to be involved in living near seven different types of technological facility. The subjects were divided into four groups: AN, living about 500 m away from a research reactor; AF, living about 1.4 km away from this reactor; two small groups living at similar distances from a district heating facility and a control group about 10 km distant from both facilities. All groups, except AN, found the item "nuclear reactor" to be the most hazardous (total sample, 3.1 on a 4 point scale). Group AN (N = 32) found this item to be the third most hazardous, 2.88/4.0; group AF (N = 31) rated the item 3.55/4.0. The difference in this response between groups AN and AF is highly significant (Mann-Whitney U-test p <= 1%). Several explanations for this finding are discussed

The Determinants of Risk Perception: The Active-Passive Dimension

In this paper the suitability of using photographs as a testing technique for identifying additional factors as determinants of risk perception is discussed. A survey was performed, showing 30 slides to 222 respondents (90 males, 132 females). The risk situations presented were to be evaluated on a rating scale. Factor analytical treatment of data revealed two factors, where the first factor can be interpreted as a "general risk" factor. The second factor displayed a two-dimensional structure, the poles of which were designated "active" and "passive" with regard to the persons depicted in the various, situations. The "active" dimension is described by a permanent struggle with the event, whereas the "passive" dimension is characterized by a submissive ability of endurance with little influence through personal skill on the situation. Technological risk situations (i.e., interaction between man and his technical environment) are mainly located on the passive side of this bi-polar continuum. Here also statistically significant differences between male and female respondents were found

A Systems Analysis Approach to Nuclear Facility Siting

In recent years there has been a growing tendency in science to conduct multi-disciplinary studies of large-scale systems. These studies include the entire spectrum of economic, technological, environmental and societal factors which characterize the complex problems of advanced industrialized societies. One of the more promising ways of addressing these problems is the broad research strategy of applied systems analysis. Basically this is a rational approach to problem-solving which attempts to identify and model interactions between the systems under study and all other systems. This results in a thorough understanding of the system being studied which may then serve as an aid in decision-making. This paper attempts to demonstrate an application of the techniques of systems analysis, which have been successful in solving a variety of problems, to the question of nuclear facility siting

A Comparative Study of Public Beliefs about Five Energy Systems

Public perceptions (n=244) of five alternative energy sources (nuclear, coal, oil, hydro, and solar) were examined using an attitude model based upon the underlying beliefs held about the attitude object (e.g., each energy system); the focus was on the differing perceptions of sub-groups (n=50) most PRO and CON the use of nuclear energy. Both PRO and CON groups preferred hydro and solar energy to the other energy sources; but the PRO Nuclear Group preferred nuclear energy to the fossil fuels while, for the CON Nuclear Group, nuclear energy was the least preferred system. Of the theoretically possible significant contributors to near-term Austrian electricity supply which were considered in this study (i.e., nuclear, coal, oil), the PRO Nuclear Group saw oil as the alternative to nuclear energy while the CON Nuclear Group preferred coal to oil as the non-nuclear alternative. Factor analysis found that five, relatively independent belief dimensions characterize public thinking about energy systems: beliefs about future-oriented and political risks; economic benefits; environmental risks; psychological/physical risks; and future technology development. Analysis of the belief systems suggested that both PRO and CON Nuclear Groups preferred hydro and solar energy because these systems were perceived as being the least threatening on all risk-related dimensions. The PRO group saw nuclear energy as the system most likely to lead to economic benefits and future technological developments; their low ratings of fossil fuels were primarily due to beliefs that the fossil fuels could provide only marginal economic benefits while leading to appreciable environmental risks. In contrast, the CON group viewed nuclear energy as only marginally more likely to provide economic and technological benefits than the fossil fuels, but as an appreciably greater threat on the risk-related dimensions

Effect of short chain fatty acids on the expression of free fatty acid receptor 2 (Ffar2), Ffar3 and early-stage adipogenesis

Adipose tissue has a major influence on insulin sensitivity. Stimulation of free fatty acid receptor 2 (FFAR2) has been proposed to influence adipocyte differentiation. We hypothesised that exposing preadipocytes to short chain fatty acids would induce earlier expression of nuclear receptors that co-ordinate adipogenesis, triglyceride accumulation and leptin secretion. 3T3-L1 preadipocytes were differentiated in the presence of 1 μM acetate, 0.1–10 μM propionate or vehicle control. In experiment 1, expression of Ffar2 and nuclear receptor mRNA was measured by quantitative PCR over 48 h following onset of differentiation. In experiment 2, extracellular leptin concentration and intracellular triglyceride content were measured at days 0, 2, 4, 6, 8 and 10 following the onset of differentiation. Control cells exhibited similar temporal dynamics of gene expression, triglyceride accumulation and leptin secretion as reported previously. We were unable to detect expression of Ffar3 mRNA at any stage of differentiation. Consistent with a lack of Ffar2 expression in the first 24 h of differentiation, acetate and propionate had no significant effect on nuclear receptor expression. Furthermore, acetate or propionate treatment did not alter leptin concentration or triglyceride content. In conclusion, we observed no significant effect of propionate or acetate on adipogenesis in 3T3-L1 cells using validated quantitative techniques

Population structure and connectivity of tiger sharks (Galeocerdo cuvier) across the Indo-Pacific Ocean basin

Population genetic structure using nine polymorphic nuclear microsatellite loci was assessed for the tiger shark () at seven locations across the Indo-Pacific, and one location in the southern Atlantic. Genetic analyses revealed considerable genetic structuring ( > 0.14,