Standing up to the big squeeze

Consumer confidence is at its lowest ebb since 1980. Economic growth is at a standstill & unemployment & inflation are both rising. Here's a front-line report from more than three dozen operators who are fending off the recession's dual pressures of slow sales & rising costs. They are using discount pricing, partnering with vendors, setting pay for performance standards & a variety of other recession-beating practices.     

Mechanical properties of certain oriented crystalline polymers

The yield stress is a simple function of the deformation ratio in the direction of testing for specimens oriented by uniaxial or biaxial stretching or rolling. Unless the yield stress increases more rapidly than in proportion to the deformation ratio, there will be instability during tensile creep under high loads. The relative merit of various polymers differs for creep and stress relaxation. Fatigue and bend recovery are also related to the molecular structure.     

Cuticular hydrocarbons ofReticulitermes virginicus (Banks) and their role as potential species- and caste-recognition cues

The cuticular hydrocarbon components of four castes ofReticulitermes virginicus (Banks) have been identified and quantitated. Components identified includen-alkanes; 2-, 3-, 11-, 13-, and 15-methyl-alkanes; 11,15-dimethylalkanes, (Z)-9-alkenes; (Z,Z)-7,9-dienes; and (E/Z)-6,9-dienes ranging in carbon number from C₂₁ to C₄₀. All caste forms ofR.virginicus contained the same components, but showed caste-specific proportions. Comparison of these hydrocarbons with those of the sympatric termiteR. flavipes (Kollar) suggest that cuticular hydrocarbons might serve as species- and caste-recognition cues. A bioassay was developed to test this species-recognition hypothesis, with the experimental results supporting the hypothesis.Isoptera: Rhinotermitidae.     

Analysing neurobiological models using communicating automata

Two important issues in computational modelling in cognitive neuroscience are: first, how to formally describe neuronal networks (i.e. biologically plausible models of the central nervous system), and second, how to analyse complex models, in particular, their dynamics and capacity to learn. We make progress towards these goals by presenting a communicating automata perspective on neuronal networks. Specifically, we describe neuronal networks and their biological mechanisms using Data-rich Communicating Automata, which extend classic automata theory with rich data types and communication. We use two case studies to illustrate our approach. In the first case study, we model a number of learning frameworks, which vary in respect of their biological detail, for instance the Backpropagation (BP) and the Generalized Recirculation (GeneRec) learning algorithms. We then used the SPIN model checker to investigate a number of behavioral properties of the neural learning algorithms. SPIN is a well-known model checker for reactive distributed systems, which has been successfully applied to many non-trivial problems. The verification results show that the biologically plausible GeneRec learning is less stable than BP learning. In the second case study, we presented a large scale (cognitive-level) neuronal network, which models an attentional spotlight mechanism in the visual system. A set of properties of this model was verified using Uppaal, a popular real-time model checker. The results show that the asynchronous processing supported by concurrency theory is not only a more biologically plausible way to model neural systems, but also provides a better performance in cognitive modelling of the brain than conventional artificial neural networks that use synchronous updates. Finally, we compared our approach with several other related theories that apply formal methods to cognitive modelling. In addition, the practical implications of the approach are discussed in the context of neuronal network based controllers.     

All-glass system for preparative gas chromatography using capillary columns

A zero dead-volume all-glass-lined stainless-steel effluent splitter with a modified thermal gradient collector was designed for preparative gas chromatography using glass capillary columns. This system gives efficient collection of extremely pure samples of the 1-ng to 10-g range for spectral analysis and biological testing.Approved as TA 15656 by the director of the Texas Agricultural Experiment Station in cooperation with ARS, USDA. Supported by the Texas Department of Agriculture interagency agreement IAC-0487 (78-79).     

Free fatty acids in cultured cells

A method for isolation and quantitation of cellular free fatty acid has been developed. When this method was used to quantitate the free fatty acid content of various cells and tissues, their levels of free fatty acids were found to vary over a wide range. In comparing tissue culture cells having different levels of free fatty acid, it was demonstrated that the conditions of culture and the type of serum in the medium are not responsible for the difference in levels. Isotopic studies have shown that the cellular free fatty acid is not biosynthesized, but is derived from the free fatty acid of the medium. Preliminary studies on the fate of the intracellular free fatty acid and a discussion of possible factors controlling the level of this compound in cells are presented.     

Male european corn borer,Ostrinia nubilalis (Hübner), antennal responses to analogs of its sex pheromone

Experiments were conducted to (1) determine whether the electroantennogram (EAG) can detect differences among the responses of antennae from males derived from the three strains ofOstrinia nubilalis (Hübner), and (2) characterize the EAG responses of each strain to isomeric forms of the natural pheromone, (E)- and (Z)-11-tetradecen-1-ol acetate (TDA), and analogs possessing differences in the terminal alkyl group, cyclopropyl (CPA), ortert-butyl (TBA).EAG responses differed among the strains in two ways: (1) Antennae fromZZ males always produced an EAG to (Z)-TDA with an extended duration of response. This signature EAG response was found to be unique to the antennal response ofZZ males to (Z)-TDA, thus providing a relatively easy method of distinguishing liveZZ males fromEE orZE males. Correlated with this longer EAG response was a longer disadaptation time, i.e., the EAG response ofZZ antennae disadapted more slowly (ca. 10 min) than the response ofEE antennae. (2) Strain differences in the relative EAG amplitudes to isomers and analogs were observed at the stimulus amounts eliciting the peak EAG amplitude as follows: TDA CPA > TBA forZZ males and both isomers; TDA > CPA TBA and CPA TDA > TBA forEE males and theE andZ isomers, respectively; CPA > TBA TDA forZE males and both isomers. Dose—response relationships were seen for all compounds if amplitude (peak height) of the EAG was used as a measure of response. However, if width of the EAG at half the peak height (peak width) was used, then only theZZ antennal response to (Z)-TDA resulted in a meaningful dose-response relationship. For all strains, the EAG amplitudes elicited by theZ isomers of any of the tested compounds were greater than those elicited by the correspondingE isomers. Therefore, correlations between the relative EAG and upwind flight responses were observed in theZZ (r = 0.86) andZE (r = 0.80) strains but were not correlated in theEE strain (r = 0.18). Temporal studies showed that adaptation, not postexcision deterioration, was responsible for the observed decreases in the EAG amplitude after repetitive stimulation or after stimulation with amounts in a descending order. Disa-daptation required at least 20 min for a moderate dose (10 g for 1 sec). Developmental studies showed that antennae from 2-day-old adults had the greatest EAG response.     

'Polymorph Method' Determination of Monoclinic Zirconia in Partially Stabilized Zirconia Ceramics

The polymorph method, which provides phase analysis from a small number of integrated intensities in a powder diffraction scan, is adapted for the determination of monoclinic zirconia in a mixture with cubic, tetragonal. and orthorhombic zirconias and the γ-phase (Mg₂Zr₅O₁₂). Such a mixture is representative of Mg-PSZ after subeutectoid aging. The quantitative determination of the monoclinic depends in principle on a knowledge of the relative amounts of the other phases present in the mixture. It is demonstrated, however, that without this knowledge, even in complex mixtures, the traditional polymorph method analysis gives an acceptable estimate of the monoclinic fraction in the sample.