The impact of the Postponing Sexual Involvement curriculum among youths in California

Postponing Sexual Involvement (PSI) is a widely implemented middle school curriculum designed to delay the onset of sexual intercourse. In an evaluation of its effectiveness among seventh and eighth graders in California, 10,600 youths from schools and community-based organizations statewide were recruited and participated in randomly assigned intervention or control groups; the curriculum was implemented by either adult or youth leaders. Survey data were collected before the program was implemented, and at three months and 17 months afterward. At three months, small but statistically significant changes were found in fewer than half of the measured attitudes, behaviors and intentions related to sexual activity; at 17 months, none of these significant positive effects of the PSI program had been sustained. At neither follow-up were there significant positive changes in sexual behavior; Youths in treatment and control groups were equally likely to have become sexually active, and youths in treatment groups were not less likely than youths in control groups to report a pregnancy or a sexually transmitted infection. The evaluation suggests that PSI may be too modest in length and scope to have an impact on youths' sexual behavior.     

Glass/Brass-270 Wire-Mesh Nanosilica Toughened Epoxy Composite: Mechanical,Impact and Fatigue Behaviour

Silicon - High toughness epoxy resin hybrid composites were prepared using nanosilica, glass fibre and brass wire-mesh. The main aim of this research was to study the effect of adding nanosilica...     

Voluntary alcohol drinking selectively accelerates dopamine release in the ventral striatum as reflected by 3-methoxytyramine levels

Alcohol-preferring Alko, Alcohol (AA) rats with free access to food and water were taught to voluntarily consume 10% alcohol solution during 20-min sessions. After the drinking session, rats had elevated dopamine release (as reflected by 3-methoxytyramine concentrations) in the nucleus accumbens, olfactory tubercle, and caudate-putamen. When alcohol solution was replaced by plain water, dopamine release was increased only in the caudate-putamen, indicating selective activation of the mesolimbic dopaminergic pathway by alcohol.     

Ultrasonographic appearance of fallopian tube carcinoma

Preoperative diagnosis of tubal carcinoma is difficult and a diagnosis cannot usually be established until the time of operation. However, since prognosis is strictly related to the stage of the neoplasm, it is very important to be familiar with the clinical and imaging characteristics of primary fallopian tube carcinoma in order to make an early and accurate diagnosis. This report presents the ultrasonographic features of three cases of fallopian tube carcinoma and reviews the literature on the subject.     

Three-dimensional atomic imaging of colloidal core-shell nanocrystals

Colloidal core-shell semiconductor nanocrystals form an important class of optoelectronic materials, in which the exciton wave functions can be tailored by the atomic configuration of the core, the interfacial layers, and the shell. Here, we provide a trustful 3D characterization at the atomic scale of a free-standing PbSe(core)-CdSe(shell) nanocrystal by combining electron microscopy and discrete tomography. Our results yield unique insights for understanding the process of cation exchange, which is widely employed in the synthesis of core-shell nanocrystals. The study that we present is generally applicable to the broad range of colloidal heteronanocrystals that currently emerge as a new class of materials with technological importance.     

Low-temperature nanocrystal unification through rotations and relaxations probed by in situ transmission electron microscopy

Through the mechanism of "oriented attachment", small nanocrystals can fuse into a wide variety of one- and two-dimensional nanostructures. This fusion phenomenon is investigated in detail by low-temperature annealing of a two-dimensional array of 10 nm-sized PbSe nanocrystals, in situ in the transmission electron microscope. We have revealed a complex chain of processes; after coalescence, the connected nanocrystals undergo consecutive rotations in three-dimensional space, followed by drastic interfacial relaxations whereby full fusion is obtained.     

Ion beam sputtering coatings on large substrates: toward an improvement of the mechanical and optical performances

Large mirrors (?350 mm) having extremely low optical loss (absorption, scattering, wavefront) were coated for the VIRGO interferometer. The new generation of mirrors needs to have a better wavefront and lower mechanical loss. To improve the component wavefront, the corrective coating technique was used. By doping the tantalum pentoxide layers, we improved, for the first time to our knowledge, the multilayer mechanical loss. The first results are discussed.