Aggressive behavior among Israeli elementary school students and associated emotional/behavioral problems and self-control.

This study aimed to identify aggression patterns among students, compare teachers' and students' reports on aggressiveness, and examine whether emotional and behavioral problems and self-control intercorrelate with aggression and can explain it among students. The study investigated 363 students aged 8 to 11 years and their 12 homeroom teachers in two elementary schools in central Israel. As expected, students reported higher verbal aggression than physical without gender differences in the general tendency. Also, students reported a higher rate of others' aggression toward them than their own aggression toward others. Similarities emerged between students' and teachers' reports. Four types of students were classified: the aggressive initiator (proactive), the aggressive responder (reactive), the passive victim, and a neutral type. An important outcome was the significant negative association of aggressiveness with self-control. Students with higher rates of self-control skills presented lower rates of aggressive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pre- and post-admission attrition of homeless, mentally ill chemical abusers referred to residential treatment programs

AIMS: To assess the magnitude and psychopathologic predictors of attrition among homeless, mentally ill chemical abusers (MICAs) referred to residential treatment programs in New York City. DESIGN: Homeless, MICAs were randomly referred to a therapeutic community (TC) or community residence (CR) and monitored with regard to pre- and post-admission attrition. SETTINGS: Community based treatment facilities modified to treat both substance abuse and major mental illness. PARTICIPANTS: Homeless individuals with a major mental illness (DSM-III-R) and a history of abusing alcohol or other drugs. MEASUREMENTS: Attrition rates and selected scales of psychopathology. FINDINGS: From an initial pool of 694 treatment candidates, 147 (22%) were rejected for admission at their assigned facility; 247 (36%) failed to show up for treatment; and 212 (31%) dropped out of treatment at some point during the first 12 months. Contrary to expectation, those with severe levels of psychotic ideation, depressive symptoms and hostility were admitted to treatment more frequently and stayed in treatment longer at the TC, a high demand approach, than the CR, a low demand approach. CONCLUSION: Clinicians should consider the TC as a viable treatment option for MICAs.     

Radiative and nonradiative relaxation phenomena in hydrogen- and oxygen-terminated porous silicon

Abstract

Using time-resolved photoluminescence spectroscopy over a wide range of temperatures, we were able to probe both radiative and nonradiative relaxation processes in luminescent porous silicon. By comparing the photoluminescence decay times from freshly prepared and oxidized porous silicon, we show that radiative processes should be linked with quantum confinement in small Si nanocrystallites and are not affected by oxidation. In contrast, nonradiative relaxation processes are associated with the state of oxidation where slower relaxation times characterize hydrogen-terminated porous silicon. These results are in a good agreement with the extended vibron model for small Si nanocrystallites.

PACS

78.55.Mb; 78.67.Rb; 78.47.jd     

Resonant coupling between surface vibrations and electronic states in silicon nanocrystals at the strong confinement regime

A striking correlation between infrared photoinduced absorption spectra and the photoluminescence from silicon nanocrystals indicates that quantized electronic sublevels of the nanocrystals are resonantly coupled to surface vibrational modes via a polarization field produced by coherent longitudinal polar vibrations. Our experimental results and model support the assumption that the mechanism responsible for the efficient photoluminescence from silicon nanocrystals should be assigned to inhibition of nonradiative channels rather than enhancement of radiative channels.     

Pyramid-shaped silicon photodetector with subwavelength aperture[for NSOM]

We present a new type of silicon photodetector with a subwavelength aperture designed to scan material surfaces with a resolution inaccessible by conventional optical microscopy. Such a probe is designed for integration into a near-field scanning optical microscope (NSOM) for scanning and collecting information from the near-field region located at the vicinity of the surface. The photodetector, which was realized by conventional microelectronics technology, is located on top of a 250-μm-high pyramid, enabling detection of reflected as well as transmitted light. The light sensitive part of the probe consists of a micromachined silicon structure built using anisotropic etch solutions such as ethylene diamine pyrocatechol (EDP) and KOH. The shape of the probe is a truncated double pyramid with a ring shape top silicon/aluminum Schottky diode surrounding an exposed silicon photosensitive area of about 150 nm in diameter. Typical I-V characteristics and optical response measurements are presented     

Observation of infrared intersubband emission in optically pumpedquantum wells

Mid-infrared intersubband emission is investigated in GaAs/AlGaAs asymmetric coupled quantum wells exhibiting an energy separation between the ground and first excited subbands close to the LO-phonon energy. The authors show that an infrared emission occurs between excited subbands under intersubband optical pumping