Magnetic bucket for rotating unmagnetized plasma

A new experiment is described which generates flow in unmagnetized plasma. Confinement is provided by a cage of permanent magnets, arranged to form an axisymmetric, high-order, multipolar magnetic field. This field configuration-sometimes called a "magnetic bucket"-has a vanishingly small field in the core of the experiment. Toroidal rotation is driven by J × B forces applied in the magnetized edge. The cross-field current that is required for this forcing flows from anodes to thermionic cathodes, which are inserted between the magnet rings. The rotation at the edge reaches 3 km/s and is viscously coupled to the unmagnetized core plasma. We describe the conditions necessary for rotation, as well as a 0-dimensional power balance used to understand plasma confinement in the experiment.     

Counterexample-guided abstraction refinement for symmetric concurrent programs

Predicate abstraction and counterexample-guided abstraction refinement (CEGAR) have enabled finite-state model checking of software written in mainstream programming languages. This combination of techniques has been successful in analysing system-level sequential C code. In contrast, there is little evidence of fruitful applications of CEGAR to shared-variable concurrent software. We attribute this gap to the lack of abstraction strategies that permit a scalable analysis of the resulting multi-threaded Boolean programs. The goal of this paper is to close this gap. We have developed a symmetry-aware CEGAR technique: it takes into account the replicated structure of programs that consist of many threads executing the same procedure, and generates a Boolean program template whose multi-threaded execution soundly overapproximates the original concurrent program. State explosion during model checking parallel instantiations of this template can now be absorbed by exploiting symmetry. We have implemented our method in a tool, SymmPa, and demonstrate its superior performance over alternative approaches on a range of synchronisation programs.     

Glass Surface Cracks Caused by Alkaline Solution Containing an Alkaline-Earth Element

When glass was treated in a hot alkaline solution containing a small amount of heavy alkaline earth elements such as Ba or Sr, sharp cracks formed on the glass surface. The severity of the crack formation was greater, the heavier the alkaline earth element. The cracks caused a drastic reduction in the mechanical strength of the glass.     

Immunolymphoscintigraphy in breast cancer: evaluation using 131I-labeled monoclonal antibody B72.3

Resistance to the organophosphates temephos and chlorpyrifos, the carbamate propoxur, the pyrethroid permethrin, and the organochloride DDT was investigated in Tunisian populations of Culex pipiens pipiens (L.) collected between 1990 and 1996. Resistance to temephos was uniformly low, reaching 10-fold in the most resistant population. In contrast, resistance to chlorpyrifos was highly variable, reaching the highest level (> 10,000-fold) recorded worldwide. The chlorpyrifos-resistant populations also were highly resistant to propoxur. Some populations also showed high resistance to permethrin (up to 5,000-fold) and moderate resistance to DDT (approximately 20-fold). Bioassays conducted in the presence of synergists showed that increased detoxification had only a minor role in resistance, although several over-produced esterases known to be involved in organophosphate resistance were detected. To better understand the factors influencing the distribution of resistance in Tunisia, the polymorphism of genes involved in organophosphate resistance (i.e., over-produced esterases and insensitive acetylcholinesterase) was investigated in relation to the genetic structure of populations studied by analyzing the electrophoretic polymorphism of "neutral" genes. Over the area studied, and despite a high level of gene flow, resistance genes showed a patchy distribution. Results are discussed in relation to the selection pressure caused by insecticide treatments.     

Thermodynamic Insight into the Effects of Water Displacement and Rearrangement upon Ligand Modifications using Molecular Dynamics Simulations

Computational methods, namely molecular dynamics (MD) simulations in combination with inhomogeneous fluid solvation theory (IFST) were used to retrospectively investigate various cases of ligand structure modifications that led to the displacement of binding site water molecules. Our findings are that water displacement per se is energetically unfavorable in the discussed examples, and that it is merely the fine balance between change in protein–ligand interaction energy, ligand solvation free energies, and binding site solvation free energies that determine if water displacement is favorable or not. We furthermore evaluated if we can reproduce experimental binding affinities by a computational approach combining changes in solvation free energies with changes in protein–ligand interaction energies and entropies. In two of the seven cases, this estimation led to large errors, implying that accurate predictions of relative binding free energies based on solvent thermodynamics is challenging. Nevertheless, MD simulations can provide insight regarding which water molecules can be targeted for displacement.     

Accelerated Natural Convergence for Pivoted Slider Bearings

A solution technique is discussed which accelerates the convergence of the pivoted slider bearing problem. The technique is based on a fully populated, three-degrees-of-freedom stiffness matrix for the hydrodynamic lubricating film. This matrix is developed using a unique perturbation method which, when used in conjunction with a finite element formulation of the Reynolds equation, yields the bearing stiffnesses in a computationally efficient manner. The resulting natural convergence of this hydrodynamic stiffness approach is examined for a typical rigid disk magnetic recording slider.     

Size-specific growth and mortality of juvenile yellow perch in southwestern Lake Michigan

Yellow perch have experienced widespread recruitment failure within Lake Michigan since the early 1990s. Efforts to explain annual recruitment variability have primarily focused on the first year of growth, while the juvenile life stage has largely been neglected. Juvenile yellow perch, age-0 through age-2, were collected annually from 2006–2010 in Illinois waters of Lake Michigan to assess temporal variability of size-at-age and size-selective mortality. Age-0 and age-2 total length at capture differed significantly between years with a maximum difference of 4.4 mm and 11.2 mm, respectively. First winter size-selective mortality was not observed for any year-class, however size-specific growth, with larger individuals growing faster than smaller counterparts, occurred during the first winter for all year-classes but 2006. Size-selective mortality was documented between age-1 and age-2 of the 2006 year-class with yellow perch less than 70 mm at age-1 not surviving through age-2. Though population level effects remain unknown, size-specific growth and mortality during the juvenile life stage may influence the size structure and year-class strength of yellow perch in southwestern Lake Michigan. Identification of size-selective mortality occurring beyond the first growing season highlights the significance of rapid growth during early life and the importance of investigating whole life stages to identify factors influencing year-class strength.     

Barnacles resist removal by crack trapping

We study the mechanics of pull-off of a barnacle adhering to a thin elastic layer which is bonded to a rigid substrate. We address the case of barnacles having acorn shell geometry and hard, calcarious base plates. Pull-off is initiated by the propagation of an interface edge crack between the base plate and the layer. We compute the energy release rate of this crack as it grows along the interface using a finite element method. We also develop an approximate analytical model to interpret our numerical results and to give a closed-form expression for the energy release rate. Our result shows that the resistance of barnacles to interfacial failure arises from a crack-trapping mechanism.     

Thick composite design for hydrogen vessels: A contribution to composite design method

Hydrogen stock vessels add new product specifications because of higher pressure use. Today static application leads up to 700 bars. But pressure devices must resist, because of certification, at 3 times pressure (2100 bars). Composite vessels give material–structure potential solutions. But designers face limits of knowledge due to actual good practices of thick composite structures use. This paper presents levels of knowledge enrichment for designers (multi-scale experiments and models), analysis of process influence on models improvement, and a discussion for an efficient testing strategy (meaning virtual testing in order to reduce the number of tests and their costs).