Unobtrusive measurement of racial bias in job-placement decisions.

Unobtrusively gathered historical data documenting recruit-classification decisions made by the US Navy were utilized to determine whether racial bias exists among classifiers. The nature of the classification procedure resulted in the essentially random assignment of over 27,000 Black and White recruits to 46 Black and White classifiers. This permitted a number of interesting comparisons and obviated numerous problems inherent in racial-bias studies. The major hypothesis that Black and White classifiers would be differentially biased in their treatment of Black and White recruits was not supported. A 2nd hypothesis that classifiers within either racial group would be differentially biased in their treatment of Black and White recruits also was not confirmed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of cellulose–solvent interaction on the mechanical properties of bonded fibrous structures

The mechanical properties, i.e., the tensile strength, tensile modulus, elongation at rupture, and tensile energy absorption (work of rupture), of a dry-formed network of cellulose fibers are shown to be substantially improved by impregnation of the network with organic solutions of poly(vinyl acetate) (PVAC). With the exception of the tensile strength, the improvement of the mechanical properties in the dry state is, however, dependent not only on the polymer content, but also on the interaction between the solvent and the cellulose fibers constituting the network. A solvent which interacts strongly with cellulose produces a stiffer and less ductile network than a more inert liquid. It is suggested that this effect is the result of a change in the cellulose network structure itself. The solvents used in this study were methanol, acetone, ethyl acetate, chloroform, and toluene.     

Enhanced cellular uptake of a glutathione selective fluorogenic probe encapsulated in nanoparticles

Selective fluorogenic probes for the labelling of intracellular reduced glutathione (GSH), i.e.?ortho-phthaldialdehyde (OPA) and naphthalene-2,3-dicarboxaldehyde (NDA), have been encapsulated in polymeric nanoparticles (NPs) and the ability of the NPs to enhance uptake of the probe by microbial cells has been evaluated. Preparation of the probe-loaded NPs composed of Eudragit(?) E was based on an oil-in-water emulsification solvent evaporation method using an ultrasonic probe and polyvinyl alcohol as the surfactant. The encapsulation efficiency of the probes in lyophilized NPs was determined using high performance liquid chromatography (HPLC). A higher encapsulation rate of NDA than OPA was found: 47.6 ± 9.9?(n = 6) and 2.1 ± 0.2%?(n = 3), respectively. The NDA-loaded particle diameter and zeta potential were 224.6 ± 14.7?nm and +40.9 ± 6.5?mV, respectively. After 20?min incubation of cultured Candida albicans yeast cells with either free NDA or NDA-loaded NPs (final NDA concentration 100?μM), cells were harvested and corresponding lysates were analysed using HPLC coupled with spectrofluorimetric detection. Incubation of cells with NDA-loaded NPs increased intracellular levels of NDA-GSH adduct by about nine-fold in comparison with the free probe. Adhesion on the cells and the penetration behaviour of NPs loaded with either NDA or fluorescent label (Nile Red) were characterized qualitatively by confocal laser scanning microscopy.     

Human vascular endothelial cells in primary cell culture for the evaluation of nanoparticle bioadhesion

Nanoparticles (NP) are employed in various therapeutic approaches for innovative drug delivery strategies. Among them, there is drug delivery to the brain and sustained release forms for intravenous drug delivery. In order to optimize drug carriers and to elucidate involved mechanisms such as bioadhesion and cellular uptake, NP were surface modified and analyzed for their interaction with human endothelial cells in cell culture. Fluorescently labeled NP of different diameters (50 to 1000 nm) were surface modified either by simple adsorption of chitosan or by covalent binding to the lectin ulex europaeus agglutinin and thereafter applied to human endothelial cells for different incubation periods. After incubation with NP the binding of NP was quantified directly by the fluorescence emission signals from the cell layers. In order to visualize the binding behaviour, NP were localized three-dimensionally in the cell layer by confocal laser scanning microscopy. Cell binding experiments in phosphate buffer were observed to be particle size dependent with the 50 nm NP showing the highest binding percentage over all experiments. Binding decreased with increasing particle diameter and shorter incubation interval. The adhesion was further enhanced by NP surface modifications in the order blank < chitosan < lectin. The presence of plasma proteins enhanced the adhesiveness of chitosan coated NP, while the binding of lectin coated NP was inhibited. Experiments at 4 degrees C indicated the involvement of an active process in the binding of NP to endothelial cells.     

Simulation of stochastic demand data streams for network revenue management problems

For evaluating heuristic and optimal network revenue management procedures test-instances are needed. As a consequence when trying to create instances for network revenue management problems it turns out that among other things a stream of stochastic demand data is required. But, developing and implementing a generator for demand data that fits to a given network, a given set of products, and a given set of capacity constraints is far from being easy. Since to the best of our knowledge no such demand data generator is available to the public, we specify an algorithm to generate this data and we also make this algorithm available upon request. This, we hope, facilitates future research work.