Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer

We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit ‘flow aligning’ dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the ‘tumbling’ type.     

Unlearned appetite controls: Watersnakes (Nerodia) take smaller meals when they have the choice.

Studies of appetite in mammals emphasize that meal size is learned, but lactation and parental care constrain testing of naive individuals. Neonatal reptiles, in contrast, are self-sufficient foragers. The authors examined the effect of prey size on meal size in primivorous (at first feeding) northern watersnakes (Nerodia sipedon). When offered an excess of small prey (2%-20% of snake mass), neonates ate significantly smaller meals (M = 23.5% of snake mass) than when offered a single huge item (range = 32%-55%). The authors conclude that (a) the taking of smaller meals is not a learned effect, (b) there may be a satiety threshold for meal size rather than a target, (c) oropharyngeal stimuli may provide satiety cues, and (d) huge meals may have fitness costs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Untersuchungen über die Naßabsiebung von Feinerzen im Feinkornbereich

Einführung einer maschinellen Naßsieb-Analysenmethode anstelle der bisher üblichen manuellen Naßsiebanalyse im Fein- und Feinstkornbereich von Eisenerzen. Verbesserung der Maschinensiebung durch Belüftung der Einzelsiebe sowie durch kontinuierliche Messung des Siebdurchganges mit Endpunktbestimmung der Siebung. Entwicklung eines Verfahrensganges zur praktikablen Ausführung einer Prüfsiebanalyse auch bei relativ großen Siebgutmengen. Erfolgreicher Abschluß der Versuche zur Reproduzierbarkeit innerhalb des eigenen Labors sowie durch Ringuntersuchungen in verschiedenen Laboratorien.     

Density-dependent foraging strategy of a large carnivorous lizard, the savanna monitor (Varanus albigularis).

Captive, subadult white-throated savanna monitor lizards (Varanus albigularis; n?=?15) were tested in a prey density-dependent foraging experiment. Within a test arena individual lizards were offered 10 large and 10 small snails in both a large and small circular area. Results showed that at high prey density, these lizards selected large over small snails. At low prey densities, however, large and small snails were selected at an equal rate. Apparently, when prey densities are high, the lizards have the opportunity to select the larger prey items without incurring locomotor costs. These data support optimal foraging theory but are unique in that they are an example from a little-studied, widely foraging species of lizard. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Aging on Premolded Elastomeric Splices for 138-kV XLPE Cable

The Electric Power Research Institute (EPRI) has completed an accelerated-life test at the Waltz Mill Cable Test Facility on twelve 138-kW factory molded splices for extruded dielectric cables to determine their suitability for utility service. After the successful completion of these tests, the aged splices were returned to the factory for post-test evaluation. Analysis showed excellent performance, demonstrating their qualification for utility service.     

Total internal reflection fluorescent microscopy

This review discusses applications of fluorescence microscopy using totally internally reflected excitation light. When totally internally reflected in a transparent solid at its interface with liquid, the excitation light beam penetrates only a short distance into the liquid. This surface electromagnetic field, called the ‘evanescent wave’, can selectively excite fluorescent molecules in the liquid near the interface. Total internal reflection fluorescence (TIRF) has been used to examine the cell/substrate contact regions of primary cultured rat myotubes with acetylcholine receptors labelled by fluorescent α-bungarotoxin and human skin fibroblasts labelled with a membrane-incorporated fluorescent lipid. TIRF examination of cell/substrate contacts dramatically reduces background from cell autofluorescence and debris. TIRF has also been combined with fluorescence photobleaching recovery and correlation spectroscopy to measure the chemical kinetic binding rates and surface diffusion constant of fluorescent labelled serum protein binding (at equilibrium) to a surface.     

Strike-induced chemosensory searching by ingestively naive garter snakes (Thamnophis sirtalis).

Neonatal, previously unfed garter snakes exposed to aqueous chemical cues from earthworms tongue flicked at higher rates during the 5 min after withdrawal of the stimulus than after aqueous control trials. If snakes struck at but did not touch the worm stimulus, they showed a much greater increase over control trials in postexposure tongue flicking than when they did not strike, and the increased rate persisted longer. These results demonstrate strike-induced chemosensory searching (SICS) by ingestively naive snakes. It is highly probable that other squamate reptiles show a similar well-integrated suite of sequential foraging behaviors at birth or hatching. Differences among species in SICS may be related to details of sequential prey capture tactics in reconstruction of phylogenetic patterns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of antipredator responses in snakes: I. Defensive and open-field behaviors in newborns and adults of three species of garter snakes (Thamnophis melanogaster, T. sirtalis, T. butleri).

A comparative study of defensive behavior in multiple litters of newborn garter snakes and adult female garter snakes from 3 species was conducted in the laboratory. In Exp I, 241 1-day-old Ss, roughly equally divided among the 3 species, were tested for defensive behaviors directed toward a moving or nonmoving stimulus. T. melanogaster babies were the most reactive in terms of strikes, bites, and defensive tongue flicks. T. sirtalis and T. butleri were less reactive and not significantly different from each other. In Exp II, 32 adult females reacted in ways similar to the neonates, except that the T. sirtalis females were more reactive toward the moving stimulus than were the T. butleri females. Exp III showed large and significant differences in open-field behavior among the newborn of the 3 species but few significant correlations between open-field measures and antipredator responses. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)