PHOTO-ELECTRIC EFFECTS IN BILAYER MEMBRANES; ELECTROMETERS AND VOLTAGE CLAMPS COMPARED

Abstract— Laser flash induced voltage transients recorded with high speed electrometers are compared to signals generated by voltage clamps, using chromophores which generate photo-electric effects in membranes by different mechanisms and with time constants that varied from < 100 ns to > 1 s. The chromophores used were; (i) azo dye, 3,3-bis-(α-(trimethylammonium)methyl) azobenzene-bromide, (ii) cyanine dye, 3,3-dimethyl-2,2-oxacarbocyanine-chloride, (iii) xanthene dye, 2,4, 5, 7-tetraiodofluorescein or erythrosin, and (iv) chlorophyll a . A scheme for classifying photo-electric effects is presented. Voltage clamp signals are functions of both apparatus and photo-current time constants. They vary with aqueous solution salt concentration, and usually mask kinetic information that may be obtained with electrometers.     

On dominator colorings in graphs

A dominator coloring of a graph G is a proper coloring of G in which every vertex dominates every vertex of at least one color class. The minimum number of colors required for a dominator coloring of G is called the dominator chromatic number of G and is denoted by ?? _d (G). In this paper we present several results on graphs with ?? _d (G)?=???(G) and ?? _d (G)?=???(G) where ??(G) and ??(G) denote respectively the chromatic number and the domination number of a graph G. We also prove that if ??(G) is the Mycielskian of G, then ?? _d (G)?+?1?????? _d (??(G))?????? _d (G)?+?2.     

TAILORING POINT COUNTS FOR INFERENCE ABOUT AVIAN DENSITY: DEALING WITH NONDETECTION AND AVAILABILITY

Point counts are commonly used for bird surveys, but interpretation is ambiguous unless there is an accounting for the imperfect detection of individuals. We show how repeated point counts, supplemented by observation distances, can account for two aspects of the counting process: (1) detection of birds conditional on being available for observation and (2) the availability of birds for detection given presence. We propose a hierarchical model that permits the radius in which birds are available for detection to vary with forest stand age (or other relevant habitat features), so that the number of birds available at each location is described by a Poisson‐gamma mixture. Conditional on availability, the number of birds detected at each location is modeled by a beta‐binomial distribution. We fit this model to repeated point count data of Florida scrub‐jays and found evidence that the area in which birds were available for detection decreased with increasing stand age. Estimated density was 0.083 (95%CI: 0.060–0.113) scrub‐jays/ha. Point counts of birds have a number of appealing features. Based on our findings, however, an accounting for both components of the counting process may be necessary to ensure that abundance estimates are comparable across time and space. Our approach could easily be adapted to other species and habitats.     

The correlation between residual stresses and delamination behavior of polymer coatings

The determination of residual stresses in thin polymer coatings is important for the prediction of failure due to delamination and cracking. If the internal tensile stresses exceed the cohesive strength of the solid coating, cracking may occur which can result in coating - substrate delamination. This is especially important in the coatings and electronics industries in which coating reliability is central to the performance of a product. There are three primary causes of residual stresses in coatings, 1.) Chemical reactions in which a condensation molecule is evolved and given off during processing, 2.) Evaporation of solvent or carrier solution during drying, and 3.) Mismatch in coefficients of thermal expansion between the substate and the coating.