Mobility of holes in the quaternary alloy In1?xGaxAsyP1?y

Hole mobilities have been measured at temperatures from 77 to 300 K in a wide range of quaternary alloys grown lattice-matched to InP substrates by liquid-phase epitaxy. Over most of the composition range the hole mobility at room temperature is lower than in InP itself, and is dominated by alloy scattering.     

The effects of age and gender on the single dose pharmacokinetics of avitriptan administered to healthy volunteers

The effects of age and gender on the single dose pharmacokinetics of avitriptan and its three metabolites were assessed in 15 young men, 15 young women, 15 elderly men and 15 elderly women. Avitriptan was administered as a 150-mg capsule after a 10-hour fast and serial plasma and urine samples were collected up to 36 hours after the dose. Plasma samples were analyzed for avitriptan and its metabolites, N-desmethyl avitriptan (ND048), O-desmethyl avitriptan (OD048), and methoxypyrimidinyl piperazine (MPP). Urine samples were analyzed for only avitriptan and MPP. Avitriptan was well tolerated in all four groups. The drug was rapidly absorbed with a median time to maximum plasma concentration (tmax) between 0.5 and 1.5 hours. No significant gender-related differences were found in the maximum plasma concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUC0-infinity) of avitriptan. Renal clearance of avitriptan was significantly smaller in young women compared with young men, but this is clinically not relevant because only 2% to 3% of the total dose is excreted unchanged. Compared with the young volunteers, mean Cmax was approximately 50% higher in the elderly but there was no difference in the AUC0-infinity between the 2 age groups. Plasma concentrations of ND048, OD048, and MPP were each 50 to 100 fold lower than those of avitriptan. Hence some age- and gender-related differences found in the pharmacokinetics of avitriptan metabolites are probably not relevant in the assessment of overall safety and efficacy of avitriptan. Based on the pharmacokinetics and tolerability, no age or gender-related dose adjustment is necessary for avitriptan.     

Operational Analysis of a Quantum Dot Optically Gated Field-Effect Transistor as a Single-Photon Detector

We report on the operation of a novel single-photon detector, where a layer of self-assembled quantum dots (QDs) is used as an optically addressable floating gate in a GaAs/Al_0.2Ga_0.8As delta-doped field-effect transistor. Photogenerated holes charge the QDs, and subsequently, change the amount of current flowing through the channel by screening the internal gate field. The photoconductive gain associated with this process makes the structure extremely sensitive to light of the appropriate wavelength. We investigate the charge storage and resulting persistent photoconductivity by performing time-resolved measurements of the channel current and of the photoluminescence emitted from the QDs under laser illumination. In addition, we characterize the response of the detector, and investigate sources of photogenerated signals by using the Poisson statistics of laser light. The device exhibits time-gated, single-shot, single-photon sensitivity at a temperature of 4 K. It also exhibits a linear response, and detects photons absorbed in its dedicated absorption layer with an internal quantum efficiency (IQE) of up to (68 plusmn18)%. Given the noise of the detection system, the device is shown to operate with an IQE of (53 plusmn 11)% and dark counts of 0.003 counts per shot for a particular discriminator level.     

Multicultural competence: Criteria and case examples.

How do you as a professional psychologist know if you are competent to treat clients whose cultural origins and values differ from your own? What awareness, knowledge, and skills do you need? With whom should you consult? When should you refer? Adopting an idiographic, inclusive approach, the authors identify 12 minimal multicultural competencies for practice and illustrate their usefulness through 3 case examples. Suggestions for how professional psychologists can augment and evaluate their own multicultural competencies are offered as well as implications for professional psychology educators. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Residual compressive stress in sputter-deposited TiC films on steel substrates

Polycrystalline TiC films with thickness between 0.1 and 2.8 microm were deposited by r.f. sputtering onto 1010 steel and borosilicate glass substrates at 200°C. All films were found to be in a state of compression. For a film grown under a given set of deposition conditions, the incremental compressive stress, i.e. the average stress in the uppermost deposited layer, was generally found to be largest near the film-substrate interface and to become constant with film thickness t_f for t_f ? 0.3 microm. However, for a given t_f the incremental stress increased with a decrease in the argon sputtering pressure P_Ar. Experimental results showed that the incremental compressive stress in bulk films could be directly related to the trapped argon concentration. Argon incorporation is due to the burial of energetic species incident on the growing film surface from two primary sources: energetic neutrals produced by Ar⁺ ions scattered off the target in binary collisions and Ar⁺ ions accelerated to the substrate owing to its induced negative potential with respect to the positive space charge region in the r.f. discharge. The trapped argon concentration from both contributions increased with decreasing P_Ar. All films grown on steel substrates exhibited good adhesion as indicated by indentation and diamond stylus scratch tests. The residual compressive stress in the films was found to be beneficial for wear-related applications in which the film was subjected to a large tensile stress.     

Growth and physical properties of ZnGeAs2

Single-phase poly crystalline chalcopyrite-structure ZnGeAs₂ ingots with an average grain size of 70 μm have been grown using a modified vertical Bridgman apparatus. The melting point of the compound was determined by differential thermal analysis (DTA) to be 860°C and corrected X-ray diffraction (XRD) peak positions were obtained. The crystals were p type with a room-temperature carrier concentration of 1.1 × 10¹⁹ cm^?3 and a corresponding mobility of 15 cm²/V s. A possible chalcopyrite-to-sphalerite phase transition, reported previously to occur to 812°C, was not observed either by DTA or by XRD of quenched samples.     

Algal productivity in 49 lake waters as determined by algal assays

Algal assays were conducted on waters from 49 American lakes to determine whether phosphorus, nitrogen, or some other nutrient was the limiting factor upon algal productivity.A comparison of the known trophic state of 23 American lakes and their bioassay response is presented. Phosphorus limited algal growth in 35 of the 49 lakes assayed. Nitrogen was limiting in eight lakes and constituents other than nitrogen and phosphorus were limiting in six lakes. The results of this study indicated phosphorus limitation decreased as the productivity of the lake waters increased.