Microstructure and indentation damage resistance of ZrB2‐20 vol.%SiC ipo‐eutectic composites

Zirconium diboride with 20 vol.% silicon carbide bulk composites were fabricated using directionally solidification (DS) and also by spark plasma sintering (SPS) of crushed DS ingots. During the DS the cooling front aligned the c‐axis of ZrB₂ grains and its Lotgering factor of f_(00l) was high as 0.98. The Vickers hardness was anisotropic and it was high as 17.6 GPa along the c‐axis and 15.3 GPa when measured in an orthogonal direction. On both surfaces, even when using 100 N indentation load, no cracks were observed, suggesting a very high resistance to crack propagation. Such anomalous behavior was attributed to the hierarchical structure of DS sample where the ZrB₂ phase was under strong compression and the SiC phase was in tension. In the SPSed sample, the microstructure was isotropic respect to the direction of applied pressure. Indentation cracks appeared around the indent corners but not emanated from the diagonals, confirming high damage resistance.     

Demonstration of down-chirped and chirp-free pulses fromhigh-repetition-rate passively mode-locked lasers

Knowledge and control of the chirp parameters of semiconductor lasers is a prerequisite to obtaining transform-limited pulses and/or to compensate for group velocity dispersion in fiber. Here, we report measurements of the sign and magnitude of chirp in high-repetition-rate mode-locked semiconductor lasers. The chirp of these monolithic lasers is measured in the frequency domain, using filtering and cross-correlation techniques. For different injection currents, a range of different chirp values is measured, including strongly down-chirped pulses at higher injection currents and transform-limited pulses to slightly up-chirped pulses at lower injection currents. The pulse chirp and the resulting broadening are due to the algebraic addition of opposite-signed chirps due to saturation of the absorption section and the gain section. These may cancel each other under some conditions, leading to a soliton-like transform-limited pulse     

The kinetics of the trimethoxyboroxine-induced thermal polymerization of phenyl glycidyl ether

The kinetics of the bulk thermal polymerization of phenyl glycidyl ether induced by trimethoxyboroxine were investigated. Infrared absorption spectroscopy and gel permeation chromatography were used to follow the course of polymerization, while proton and boron-11 NMR spectroscopy were used to support the kinetic model developed. The postulated mechanism involves a fast-initiated, nonstationary cationic polymerization with five elementary steps, including spontaneous and monomer transfer as well as a termination reaction. The trimethoxyboroxine was found to be incorporated into the structure of the cured polymer. The polymerization was followed at several temperatures and with several ratios of initial concentrations of trimethoxyboroxine to phenyl glycidyl ether.     

Hassles, coping, and depressive symptoms in an elderly community sample: The role of mood regulation expectancies.

To extend research on the role of expectancy in coping, 96 individuals aged 65 yrs or older (M?=?74.46, SD?=?6.28) from non-nursing-home residential communities and organizations completed measures of daily hassles, situational coping responses, depressive symptoms, and generalized expectancies for negative mood regulation, defined as beliefs about one's ability to alleviate a negative mood. Scores from the Negative Mood Regulation Scale (S. J. Catanzaro and J. Mearns, 1990) were negatively associated with avoidant coping and depressive symptoms, independent of hassles and coping responses. As in college student samples, active coping was positively related to depressive symptoms, but only when negative mood regulation expectancies were controlled. The relations of hassles and expectancies with coping responses were weaker than those found previously in younger samples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stochastic Model for Multilane Traffic Effects on Bridges

In modern approaches, the target and design values for traffic effects on bridges are obtained through suitable stochastic traffic models processing recorded traffic data. To this aim, several theoretical and numerical stochastic models have recently been proposed. Despite their elegance, theoretical models often have limited fields of application, while numerical models, particularly efficient when single-lane traffic flow is considered, turn out to be unsatisfactory when traffic in several lanes, or a combination of traffic actions with those from other sources must be dealt with. This paper presents a more general theoretical stochastic traffic model, which is able, not only to reproduce actual traffic, but to account for such traffic interactions as well. The model, based on an equilibrium renewal process of vehicle arrivals, can be used in all cases where sophisticated evaluation of real traffic effects is required, such as calibration of conventional load models in bridge codes, assessment of existing bridges, as well as the design and analysis of bridges with less traditional schemes or subjected to particular traffic conditions. The efficiency of the model is illustrated through meaningful applications.     

Reproducibility of intracranial volume measurement by unsupervised multispectral brain segmentation

To assess the inter-study variability of a recently published unsupervised segmentation method (Magn. Reson. Med. 1997;37:84-93), 14 brain MR studies were performed in five normal subjects. Standard deviations for absolute and fractional volumes of intracranial compartments, which reflect the experimental variability, were smaller than 16.5 ml and 1.1%, respectively. By comparing the experimental component of the variability with the variability observed in our reference database, an estimate of the biological variability of the intracranial fractional volumes in the database population was obtained.     

Bulimarexia, bulimia, and binge eating: A bibliography.

Bulimarexia and bulimia are eating disorders that primarily affect women and involve eating large quantities of food followed by purging through the use of laxatives, vomiting, or other induced means. Bulimarexia and bulimia have recently received a great deal of public and professional attention. The present authors discuss the differences in these 2 terms and present a bibliography that contains 89 citations directly related to the topic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tumor clearance of technetium 99m-sestamibi as a predictor of response to neoadjuvant chemotherapy for locally advanced breast cancer

PURPOSE: Since we have previously shown that the efflux rate of technetium 99m (99mTc) sestamibi, a transport substrate of P-glycoprotein (Pgp), is directly correlated with Pgp levels in untreated breast carcinoma, we tested whether tumor clearance of 9mTc-sestamibi may be predictive of therapeutic response to neoadjuvant chemotherapy in patients with locally advanced breast cancer. PATIENTS AND METHODS: Thirty-nine patients with stage III disease, median tumor diameter 5.8 cm (range, 3 to 10) were enrolled onto this prospective clinical trial and underwent 99mTc-sestamibi scan before neoadjuvant chemotherapy. Patients were injected intravenously (i.v.) with 740 MBq of 99mTc-sestamibi; a 15-minute dynamic study was performed, and static planar images were obtained at 0.5, 1, 2, and 4 hours. The time to half clearance of 99mTc-sestamibi was calculated in each patient from decay corrected time-activity curves using a monoexponential fitting. Patients were treated with epirubicin 150 mg/m2 i.v. every 2 weeks for three courses and then underwent surgery within 3 weeks from the completion of chemotherapy. Residual tumor was assessed by pathologic examination of mastectomy specimens. RESULTS: Seventeen of 39 patients showed a rapid tumor clearance of 9mTc-sestamibi (time to half clearance [t1/2] < or = 204 minutes) and 15 of these 17 (88%) showed a highly cellular macroscopic residual tumor at histology that indicated lack of tumor response to neoadjuvant chemotherapy. In contrast, only eight of 22 (36%) with prolonged retention of 99mTc-sestamibi (t1/2 > 204 minutes) showed residual macroscopic tumor at histology (Fisher's exact test, P < .01). CONCLUSION: A rapid tumor clearance of 99mTc-sestamibi may predict lack of tumor response to neoadjuvant chemotherapy with drugs affected by the multidrug-resistant phenotype in patients with locally advanced breast carcinoma.