Health-related possible selves in young and middle adulthood.

The construct of possible selves was used to examine when, in the adult life span, health-related goals become dominant. It was predicted that by middle age most adults would have health-related possible selves and that the strength of self-regulatory variables associated with health-related possible selves would be related to reported health behaviors. Data collected from 171 young (aged 24–39 yrs) and middle-aged (aged 40–59 yrs) adults showed that health-related possible selves become predominant in midlife. In addition, both young and middle-aged adults reported more feared than hoped-for selves in the realm of health. Perceived self-efficacy and number of goal-oriented activities to avoid feared health-relevant selves were significant predictors of health behaviors. Results are discussed in relation to theoretical perspectives on self and health processes over the life span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism

Nano-Micro Letters - Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize...     

Intraoperative magnetic resonance imaging with the magnetom open scanner: concepts, neurosurgical indications, and procedures: a preliminary report

OBJECTIVE: Intraoperative magnetic resonance imaging (MRI) is now available with the General Electric MRI system for dedicated intraoperative use. Alternatively, non-dedicated MRI systems require fewer specific adaptations of instrumentation and surgical techniques. In this report, clinical experiences with such a system are presented. METHODS: All patients were surgically treated in a "twin operating theater," consisting of a conventional operating theater with complete neuronavigation equipment (StealthStation and MKM), which allowed surgery with magnetically incompatible instruments, conventional instrumentation and operating microscope, and a radiofrequency-shielded operating room designed for use with an intraoperative MRI scanner (Magnetom Open; Siemens AG, Erlangen, Germany). The Magnetom Open is a 0.2-T MRI scanner with a resistive magnet and specific adaptations that are necessary to integrate the scanner into the surgical environment. The operating theaters lie close together, and patients can be intraoperatively transported from one room to the other. This retrospective analysis includes 55 patients with cerebral lesions, all of whom were surgically treated between March 1996 and September 1997. RESULTS: Thirty-one patients with supratentorial tumors were surgically treated (with navigational guidance) in the conventional operating room, with intraoperative MRI for resection control. For 5 of these 31 patients, intraoperative resection control revealed significant tumor remnants, which led to further tumor resection guided by the information provided by intraoperative MRI. Intraoperative MRI resection control was performed in 18 transsphenoidal operations. In cases with suspected tumor remnants, the surgeon reexplored the sellar region; additional tumor tissue was removed in three of five cases. Follow-up scans were obtained for all patients 1 week and 2 to 3 months after surgery. For 14 of the 18 patients, the images obtained intraoperatively were comparable to those obtained after 2 to 3 months. Intraoperative MRI was also used for six patients undergoing temporal lobe resections for treatment of pharmacoresistant seizures. For these patients, the extent of neocortical and mesial resection was tailored to fit the preoperative findings of morphological and electrophysiological alterations, as well as intraoperative electrocorticographic findings. CONCLUSION: Intraoperative MRI with the Magnetom Open provides considerable additional information to optimize resection during surgical treatment of supratentorial tumors, pituitary adenomas, and epilepsy. The twin operating theater is a true alternative to a dedicated MRI system. Additional efforts are necessary to improve patient transportation time and instrument guidance within the scanner.     

Effect of pressure and temperature on viscosity of a borosilicate glass

During industrial glass production processes, the actual distribution of stress components in the glass during scribing remains, to date, poorly quantified, and thus continues to be challenging to model numerically. In this work, we experimentally quantified the effect of pressure and temperature on the viscosity of SCHOTT N‐BK7^® glass, by performing in situ deformation experiments at temperatures between 550 and 595°C and confining pressures between 100 and 300 MPa. Experiments were performed at constant displacement rates to produce almost constant strain rates between 9.70 × 10^?6 and 4.98 × 10^?5 s^?1. The resulting net axial stresses range from 81 to 802 MPa, and the finite strains range from 1.4% to 8.9%. The mechanical results show that the SCHOTT N‐BK7^® glass is viscoelastic near the glass transition temperature at 300 MPa of confining pressure. To elucidate the data, we incorporated both 1‐element and 2‐element generalized Maxwell viscoelastic models in an inversion approach, for which we provide MATLAB scrips. Results show that the 2‐element Maxwell model fits the experimental data well. The stress decreases with increasing temperature at 300 MPa and the temperature dependence yields a similar activation energy (601 ± 10 kJ mol^?1 or ?H/R = 7.2 × 10⁴ K) to a previously reported value at 1‐atm (615 kJ mol^?1 or ?H/R = 7.4 × 10⁴ K). The SCHOTT N‐BK7^® glass shows a limited linear increase in viscosity with increasing pressure of ~0.1 log₁₀ (Pa·s)/100 MPa, which is in agreement with the most recent 2‐internal‐parameter relaxation model (based on experiments).     

Densification and properties of zirconia prepared by three different sintering techniques

Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y₂O₃, prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (≥96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 μm after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size.     

Pressure dependence of density and structural relaxation of glass near the glass transition region

A simplified and effective pressure cell together with an experimental procedure has been developed and applied to compress samples of SCHOTT N‐BK7^® glass under static high pressures in a piston‐cylinder apparatus. Results from the density and volume recovery measurements show that, the glass samples were effectively densified in piston‐cylinder apparatus with the density at room temperature increasing linearly with frozen‐in pressure. To explain the experimental data, we developed a mathematical model based on a suggestion by Gupta (1988) with two internal parameters, named fictive temperature (T_f) and fictive pressure (P_f), which fits the experimental data well.     

Automated 3-D PDM construction from segmented images using deformable models

In recent years, several methods have been proposed for constructing statistical shape models to aid image analysis tasks by providing a priori knowledge. Examples include principal component analysis of manually or semiautomatically placed corresponding landmarks on the learning shapes [point distribution models (PDMs)], which is time consuming and subjective. However, automatically establishing surface correspondences continues to be a difficult problem. This paper presents a novel method for the automated construction of three-dimensional PDM from segmented images. Corresponding surface landmarks are established by adapting a triangulated learning shape to segmented volumetric images of the remaining shapes. The adaptation is based on a novel deformable model technique. We illustrate our approach using computed tomography data of the vertebra and the femur. We demonstrate that our method accurately represents and predicts shapes.     

Technical accuracy of a neuronavigation system measured with a high-precision mechanical micromanipulator

OBJECTIVE: This study was designed to determine and evaluate the different system-inherent sources of erroneous target localization of a light-emitting diode (LED)-based neuronavigation system (StealthStation, Stealth Technologies, Boulder, CO). METHODS: The localization accuracy was estimated by applying a high-precision mechanical micromanipulator to move and exactly locate (+/- 0.1 micron) the pointer at multiple positions in the physical three-dimensional space. The localization error was evaluated by calculating the spatial distance between the (known) LED positions and the LED coordinates measured by the neuronavigator. The results are based on a study of approximately 280,000 independent coordinate measurements. RESULTS: The maximum localization error detected was 0.55 +/- 0.29 mm, with the z direction (distance to the camera array) being the most erroneous coordinate. Minimum localization error was found at a distance of 1400 mm from the central camera (optimal measurement position). Additional error due to 1) mechanical vibrations of the camera tripod (+/- 0.15 mm) and the reference frame (+/- 0.08 mm) and 2) extrapolation of the pointer tip position from the LED coordinates of at least +/- 0.12 mm were detected, leading to a total technical error of 0.55 +/- 0.64 mm. CONCLUSIONS: Based on this technical accuracy analysis, a set of handling recommendations is proposed, leading to an improved localization accuracy. The localization error could be reduced by 0.3 +/- 0.15 mm by correct camera positioning (1400 mm distance) plus 0.15 mm by vibration-eliminating fixation of the camera. Correct handling of the probe during the operation may improve the accuracy by up to 0.1 mm.