In situ FT-IR measurements of competitive vapor adsorption into porous thin films containing silica nanoparticles

Vapor adsorption into porous ultrathin films on a gold surface is investigated with in situ surface plasmon resonance (SPR) and polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The thin films are prepared by the electrostatic self-assembly of oppositely charged poly(L-lysine) (PL) and silica nanoparticles on a chemically modified gold surface. Characterization with ex situ SPR and PM-IRRAS demonstrates the buildup of multiple PL/SiO2 bilayers as well as an excellent correlation between the quantitative results from these two techniques. In situ vapor adsorption experiments with these thin films show evidence of porosity, reproducibility, and rapid reversibility. Exposure to acetone vapor (P/P0 = 0.032) causes the film to adsorb 9% acetone by volume, which corresponds to coverage of approximately one-half of the silica nanoparticle surface area. In situ PM-IRRAS provides much information about the molecular interactions occurring in the film upon adsorption or desorption of vapors. Dosing with a mixture of vapors leads to a competition for adsorption into the film, and PM-IRRAS results show that acetone slightly outcompetes nitromethane. These experiments with nanoparticle thin films demonstrate the advantages of using in situ PM-IRRAS for studying reversible adsorption in the presence of vapor mixtures.     

Violence classifications and their impact on observed relationships with key factors in young offenders.

The understanding of violent criminal behavior is hindered by definitional problems in both the legal and research communities. Different definitions of violent criminal behavior and different classifications of the severity of violence are fundamental problems that need to be resolved in order to develop better conceptual models of the precursors to criminal violence that can inform management and treatment of violent young offenders. This study evaluated 6 classifications of violent juvenile offenses derived from the legal system and published research. The authors compare frequencies from different classifications and examine the influence of classifications on observed associations with expected predictor variables. Differences in frequencies and perceived associations between classifications highlight the need to adopt a consistent method of coding violent offenses for research purposes in order to obtain valid results that are capable of informing policy, the judiciary, and the development of effective interventions. The final classification system offers a method of systematic coding based on the type, frequency, and outcome of the violent behavior that distinguishes between levels of violence severity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impedance criterion for power modules comparison

It is well known that power modules must exhibit as low as possible stray inductance. However, the total inductance of a power module is not the only parameter to indicate the electrical quality of the packaging. In this paper, mathematical criteria will be given, which will allow the evaluation of power modules interconnects with regard to several objectives: equal current constraints among the different paralleled dies, power-drive, and even drive-drive interactions.     

Analysis of injection-locked gain-guided diode laser arrays

A new model for injection-locked gain guided laser arrays is proposed. Diffraction-limited and single-lobe operation of injection-locked arrays is attributed to coherent summation of several transverse modes that are phase locked by injection. The model predicts far-field and near-field patterns, locking bandwidth, beam-steering properties, and locked output power. The effects of varying the master power, beam shape, position, and incidence angle on the slave array facet are also studied. Theoretical and experimental results are compared     

Information capacity of the Poisson channel

The information capacity of the Poisson channel with random or time-varying noise intensity is obtained for time-varying peak and average constraints on the encoder intensity. The channel model is specified, and some definitions from information theory are given. Causal feedback is shown not to increase the channel capacity for the case of nonrandom noise intensity. For random noise intensity, use of causal feedback does increase capacity; the extent of that increase is quantified. Jamming is considered, and the optimal jamming signal is given. Poisson channels with thinning are introduced     

The Glu318Gly mutation of the presenilin-1 gene does not necessarily cause Alzheimer's disease

In early-onset familial Alzheimer's disease (AD) pathogenic mutations have been found in the amyloid precursor protein (APP) gene and in the presenilin (PS)-1 and PS-2 genes. We screened for mutations in these genes in 20 patients with familial AD from the Finnish population. In addition, we sampled 41 sporadic AD patients and 59 controls to test for mutations identified in our familial AD cases. We detected an A-to-G transition in the PS-1 gene, resulting in a glutamic acid (Glu)-to-glycine (Gly) substitution at codon 318 in 2 familial and 2 sporadic AD patients. The Glu318Gly mutation has previously been reported to cause AD. We also found the Glu318Gly mutation in 4 healthy aged controls (range, 74-87 years). We thus conclude that the mutation is most likely a rare polymorphism not related to AD.