Host and Habitat Use by Parasitoids (Hymenoptera: Pteromalidae) of House Fly and Stable Fly (Diptera: Muscidae) Pupae

House fly and stable fly pupae were collected during the summer from a dairy farm in northern Illinois. Spalangia nigroaenea accounted for most of the parasitoids recovered from house flies. Spalangia nigra, S. endius, Muscidifurax spp., and S. nigroaenea accounted for most of the parasitoids from stable flies. The majority of flies were house flies late in the summer and stable flies early in the summer. Higher percentages of house flies tended to be in samples containing lower substrate moisture and higher substrate temperature. Parasitism of stable flies started earlier and peaked weeks before that of house flies, with overall parasitism highest from mid-to late-summer. Parasitism of house flies, but not stable flies, differed significantly among habitats, being greater in calf hutches than in edge samples. Hymenopterous parasitoids from house flies tended to include a greater percentage of S. nigroaenea (and a lower percentage of Muscidifurax spp.) in calf hutches versus drainage or edge habitats and in sub- strates consisting of mostly wood shavings versus mostly manure. Within samples, differential parasitism of fly species was not detected for S. nigroaenea, S. endius, or Muscidifurax spp.; but S. nigra preferentially parasitized stable flies

Transonic separated flow predictions based on a mathematically simple, nonequilibrium turbulence closure model

A mathematically simple, turbulence closure model designed to treat transonic airfoil flows even with massive separation is described. Numerical solutions of the Reynolds-averaged, Navier-Stokes equations obtained with this closure model are shown to agree well with experiments over a broad range of test conditions

Coal thickness gauge using RRAS techniques, part 1

A noncontacting sensor having a measurement range of 0 to 6 in or more, and with an accuracy of 0.5 in or better is needed to control the machinery used in modern coal mining so that the thickness of the coal layer remaining over the rock is maintained within selected bounds. The feasibility of using the radiofrequency resonance absorption (RRAS) techniques of electron magnetic resonance (EMR) and nuclear magnetic resonance (NMR) as the basis of a coal thickness gauge is discussed. The EMR technique was found, by analysis and experiments, to be well suited for this application

Separated transonic airfoil flow calculations with a nonequilibrium turbulence model

Navier-Stokes transonic airfoil calculations based on a recently developed nonequilibrium, turbulence closure model are presented for a supercritical airfoil section at transonic cruise conditions and for a conventional airfoil section at shock-induced stall conditions. Comparisons with experimental data are presented which show that this nonequilibrium closure model performs significantly better than the popular Baldwin-Lomax and Cebeci-Smith equilibrium algebraic models when there is boundary-layer separation that results from the inviscid-viscous interactions

A Bayesian approach to bandwidth selection for multivariate kernel regression with an application to state-price density estimation.

Multivariate kernel regression is an important tool for investigating the relationship between a response and a set of explanatory variables. It is generally accepted that the performance of a kernel regression estimator largely depends on the choice of bandwidth rather than the kernel function. This nonparametric technique has been employed in a number of empirical studies including the state-price density estimation pioneered by Aït-Sahalia and Lo (1998). However, the widespread usefulness of multivariate kernel regression has been limited by the difficulty in computing a data-driven bandwidth. In this paper, we present a Bayesian approach to bandwidth selection for multivariate kernel regression. A Markov chain Monte Carlo algorithm is presented to sample the bandwidth vector and other parameters in a multivariate kernel regression model. A Monte Carlo study shows that the proposed bandwidth selector is more accurate than the rule-of-thumb bandwidth selector known as the normal reference rule according to Scott (1992) and Bowman and Azzalini (1997). The proposed bandwidth selection algorithm is applied to a multivariate kernel regression model that is often used to estimate the state-price density of Arrow-Debreu securities. When applying the proposed method to the S&P 500 index options and the DAX index options, we find that for short-maturity options, the proposed Bayesian bandwidth selector produces an obviously different state-price density from the one produced by using a subjective bandwidth selector discussed in Aït-Sahalia and Lo (1998).Black-Scholes formula, Likelihood, Markov chain Monte Carlo, Posterior density.

Health, the outdoors and safety

While the public health benefits accruing from exposure to the outdoors, and especially the natural environment, have gained greater recognition, this has exposed rifts in thinking between those focusing on the pathology of injury and those pursuing a wider health agenda which recognizes the restorative potential of encounters with nature. In retrospect, the classification of injury as a public health issue in the mid-20th century triggered complex societal responses which generated unintended consequences affecting healthful activities. Responses generally aim to reduce or minimize the risk of injury and come in different forms, including formal and informal codes of practice, standards, management systems and regulation. Well-intentioned as these interventions may have been, the new emphasis on harm shifted attention away from what causes health and resulted in increasing control over activities, including those taking place outdoors. This article, which draws on long-term qualitative policy research, describes examples of these on-going tensions in the context of the public enjoyment of the outdoors. In conclusion, the situation presented is considered from a number of theoretical perspectives, and proposals are made for resolving the issues. These include improved communication between sectors and, on the technical side, the introduction of a compensatory decision process which enables policy makers to take account of both the health benefits and risks of exposure to the natural environment