A Latent Class Analysis of Community Violence Exposure and Peer Delinquency in African American Adolescents

Aims Person-based analyses have demonstrated wide variability among the levels of exposure to community violence (ECV) experienced by youth in disadvantaged communities. In addition, social network research has found that violence victimization tends to occur primarily among a small social group, demonstrating that levels of peer delinquency may be a factor that distinguishes among youth who experience high and low levels of ECV. Methods The current study utilized latent class analysis to examine profiles of ECV and peer delinquency in a sample of 618 African American adolescents (54.7% female; mean age = 15.8, SD = 1.41), and the relationship these profiles have to adaptive and maladaptive outcomes. Results Results demonstrated that levels of ECV and peer delinquency vary significantly among these youth, and profile membership predicts levels of delinquency, aggression, future orientation, and self-esteem. Conclusion Research and clinical implications are discussed

A cohesive zone model for fracture initiation and propagation of fused silica direct bonding interface

International audienceFused silica direct bonding is of particular interest for optical system manufacturing for spatial applications. However, in order to validate the European Space Agency standards, a better understanding of the assemblies mechanical behavior is required. Therefore, it is important to develop some predictive tools to determine numerically mechanical strength of complex assemblies. In this paper, a cohesive zone model is proposed to model the direct bonding interface behavior. In order to determine the mechanical strength of the interface, a propagation test, and an initiation test on a free edge the cleavage test have been performed on direct bonded fused silica samples. The FIT test (Flexible Initiation Test) is also used to identify the properties of the direct bonding joint. At the end, a comparative analyses is proposed between experimental results and finite elements models of the propagation and initiation tests

Spectroscopy of vibrational modes in metal nanoshells

We study the spectrum of vibrational modes in metal nanoparticles with a dielectric core. Vibrational modes are excited by the rapid heating of the particle lattice that takes place after laser excitation, and can be monitored by means of pump-probe spectroscopy as coherent oscillations of transient optical spectra. In nanoshells, the presence of two metal surfaces results in a substantially different energy spectrum of acoustic vibrations than for solid particles. We calculated the energy spectrum as well as the damping of nanoshell vibrational modes. The oscillator strength of fundamental breathing mode is larger than that in solid nanoparticles. At the same time, in very thin nanoshells, the fundamental mode is overdamped due to instantaneous energy transfer to the surrounding medium

Cohomology of skew-holomorphic Lie algebroids

We introduce the notion of skew-holomorphic Lie algebroid on a complex manifold, and explore some cohomologies theories that one can associate to it. Examples are given in terms of holomorphic Poisson structures of various sorts.Comment: 16 pages. v2: Final version to be published in Theor. Math. Phys. (incorporates only very minor changes