Controlled Nucleation of GaN Nanowires Grown with Molecular Beam Epitaxy

The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiN_x prior to molecular beam epitaxy growth. Nanowire growth is uniform within mask openings and absent on the mask surface for over 95% of the usable area of a 76 mm diameter substrate. The diameters of the resulting nanowires are controlled by the size of the mask openings. Openings of approximately 500 nm or less produce single nanowires with symmetrically faceted tips.     

Operating Characteristics of Lithium Drift Detectors

A study of the operating characteristics of diffused window lithium drift silicon detector has revealed that the level of compensation is independent of depth. The compensation corresponds to a net impurity concentration of 5 × 1010 impurities per cubic centimeter and is approximately three order of magnitude poorer than that set by current flow through a diode. Using time stability studies it is possible to differentiate between stability of compensation in the bulk or main body of the detector and in the window (diffused type) area of the diode. By appropriate biasing a lithium distribution can be obtained in the window area which has good time stability. The stability of the compensation in the bulk of the diode is sufficiently high that the diffused window detector will provide many years of operation, even when the detector is left largely unbiased.     

Contributions of neuroimaging to neuropsychological research on closed head injury.

Reviews the contributions of neuroimaging to research on neuropsychological outcome of closed head injury. Studies quantifying cerebral atrophy and investigations of focal brain lesions are discussed. Use of magnetic resonance imaging (MRI) to characterize the location, size, and depth of focal brain lesions is reviewed. The disparities between the findings of computerized tomography (CT) and MRI are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PML absorbing boundary conditions for the characterization of openmicrowave circuit components using multiresolution time-domaintechniques (MRTD)

The multiresolution time domain technique (MRTD) is applied to the modeling of open microwave circuit problems. Open boundaries are simulated by the use of a novel formulation of the perfect matching layer (PML) absorber. The PML is modeled both in split and nonsplit forms and can be brought right on the surface of the planar components. The applicability of the MRTD technique to complex geometries with high efficiency and accuracy in computing the fields at discontinuities is demonstrated through extensive comparisons to conventional finite difference time domain (FDTD). In addition, the numerical reflectivity of the PML absorber is investigated for a variety of cell sizes, some of which are very close to the Nyquist limit (λ/2)     

FACTORS AFFECTING THE RESISTANCE OF SILICA REFRACTORIES TO ABRASION1

The resistance to abrasion is tested by grinding a groove in the surface of the refractory by means of a carborundum wheel with suitable mounting. Other methods used in the tests are discussed. Factors affecting resistance of silica brick to abrasion are porosity and degree of burn. Porosity is affected by grind, quality of ganister, per cent lime and workmanship. Data are given showing a rough relation between length of groove, porosity and burn.     

Effect of prepartum selenium treatment on uterine involution in the dairy cow

Selenium injections and oral vitamin E supplementation prepartum were related to: postpartum uterine involution (decrease in uterine size per unit time) and days to minimum uterine size in a 2 X 2 factorial design. Complete data were analyzed from 64 cows. Groups were selenium plus vitamin E, vitamin E, selenium, and control. Factors significantly affecting uterine size between 14 and 50 d postpartum were cow weight, days postpartum-linear, days postpartum-quadratic, day X metritis, and day X metritis X selenium treatment. Days to minimum uterine size were significantly less in cows with metritis and selenium treated when compared with cows with metritis and not selenium treated (32.9 vs. 35.8).