Microscopic modeling of gain and luminescence in semiconductors

The capabilities of a fully microscopic approach for the calculation of optical material properties of semiconductor lasers are reviewed. Several comparisons between the results of these calculations and measured data are used to demonstrate that the approach yields excellent quantitative agreement with the experiment. It is outlined how this approach allows one to predict the optical properties of devices under high-power operating conditions based only on low-intensity photo luminescence (PL) spectra. Examples for the gain-, absorption-, PL- and linewidth enhancement factor-spectra in single and multiple quantum-well structures, superlattices, Type II quantum wells and quantum dots, and for various material systems are discussed.     

500 /spl mu/m diameter CMOS compatible avalanche photodiodes with 500 MHz bandwidth

Novel silicon-on-insulator, large area (500 /spl mu/m diameter), CMOS avalanche photodiodes for use with plastic optical fibre are presented. Patterns have been formed on the devices to reduce junction capacitance. Measurements on the patterned devices, at 650 nm and 26 V reverse bias, revealed bandwidths of >500 MHz.     

Moving-focus versus self-waveguiding model for long-distancepropagation of femtosecond pulses in air

Experiments on focused femtosecond pulse propagation in air in the infrared which can test whether a strict moving-focus model interpretation is applicable were recently analyzed by Lange et al. Using numerical simulations, we show that filament propagation can be given a consistent interpretation in terms of the dynamic spatial replenishment model. While the moving-focus model cannot explain the persistence of a filament past the linear focus, the self-waveguiding model also presents problems of interpretation     

Integrative cognitive–behavioral and spiritual counseling for rural dementia caregivers with depression.

Objective: Discuss initial evaluation of a program for training faith community nurses (FCNs) to conduct cognitive–behavioral and spiritual counseling (CBSC) for rural dementia caregivers (CGs), and present 2 case studies on the use of CBSC for treating depression in this population. Study Design: Pre–post evaluation of the effectiveness of CBSC training and a case study analysis of the effectiveness of CBSC on CG problem improvement and depression. Outcome Measures: For FCN training, we used the FCN Counseling Comfort Scale, FCN Counseling Efficacy Scale, and the FCN Counseling Workshop Satisfaction Survey. The Problem Severity Scale and Center for Epidemiologic Studies Depression Scale were used in the case studies. Results: Significant post-training increases in FCN counseling comfort and perceived counseling efficacy were obtained. Case study findings provided evidence of substantial improvement in caregiving problems and reductions in depression. Conclusions: Preliminary outcomes of FCN training and CBSC for dementia CGs were promising. However, replication across the sample is required to evaluate the overall effectiveness of CBSC for reducing CG depression. Specific competencies and ethical considerations in supervising this form of intervention are also addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical Forces on a Quantum Dot in Metallic Bowtie Structures

We present a numerical scheme to calculate the electromagnetic force on a quantum dot in the near-field of subwavelength metallic nano-structures. As an application, we examine the forces on a quantum dot placed in the center of a gold nano-structure. The forces on the quantum dot are calculated using an adaptive mesh refinement finite-difference time-domain code combined with microscopic material equations. Is is shown that the dot may be laterally confined in the proposed geometry.     

Development and validation of the State Hope Scale.

Defining hope as a cognitive set comprising agency (belief in one's capacity to initiate and sustain actions) and pathways(belief in one's capacity to generate routes)to reach goals, the Hope Scale was developed and validated previously as a dispositional self-report measure of hope ( C. R. Snyder et al, see record 1991-17270-001). The present 4 studies were designed to develop and validate a measure of state hope. The 6-item State Hope Scale is internally consistent and reflects the theorized agency and pathways components. The relationships of the State Hope Scale to other measures demonstrate concurrent and discriminant validity; moreover, the scale is responsive to events in the lives of people as evidenced by data gathered through both correlational and causal designs. The State Hope Scale offers a brief, internally consistent, and valid self-report measure of ongoing goal-directed thinking that may be useful to researchers and applied professionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A large-core compact high-power single-mode photonic crystal fiber laser

A novel method for making a compact high-power single-mode photonic crystal fiber laser (PCFL) is proposed. The entire photonic crystal fiber is doped uniformly with active material yet only the core is pumped. Numerical simulations predict that, by using Er-Yb codoped phosphate glass, it is possible to extract 9.5 W from a 1.8-cm-long PCFL with a 100-/spl mu/m core diameter pumped with 20 W, achieving near 50% efficiency.     

Propagation and stability of optical pulses in nonlinear planarstructures with instantaneous and finite response times

The propagation of optical pulses in nonlinear waveguide and directional coupler structures consisting of linear and self-focusing media is studied numerically. Instantaneous and integrating nonlinearities are considered. A comparison of the stability of waveguide modes and coupling characteristics under such conditions is made. Finite medium responses times are shown to lead to an increase in the stability of pulses propagating in waveguide structures. For directional coupler geometries it is shown that finite response times lead to a loss of definition between the cross and bar states as the coupling efficiencies of more intense pulses are increased. These effects are found to be dependent on the initial, spatial, and temporal pulse profiles     

The eating quality of meat of steers fed grass and/or concentrates

The objective was to determine, relative to animals expressing their full potential for carcass growth, the impact on meat quality of increasing carcass growth of grazing steers by supplementing with concentrates or by increasing grass supply. Sixty-six continental (Limousin and Charolais) crossbred steers (567 kg) were assigned to one of six diets: (1) 18 kg grass dry matter (DM); (2) 18 kg grass DM grass and 2.5 kg concentrate; (3) 18 kg grass DM and 5 kg concentrate; (4) 6 kg grass DM and 5 kg concentrate; (5) 12 kg grass DM and 2.5 kg concentrate; or (6) concentrates daily. Animals were slaughtered after an average of 95 days. Samples of the M. longissmus dorsi (LD) were collected at the 8–9th rib interface and subjected to sensory analysis and to other assessments of quality following 2, 7, or 14 days aging. Carcass weight gain averaged 360, 631, 727, 617, 551 and 809 g/day for treatments 1 to 6, respectively. There was no difference between diets for colour, Warner–Bratzler shear force (WBSF) or any sensory attribute of the LD. WBSF was negatively correlated with (P<0.05) carcass growth rate (−0.31) but only a small proportion of the variation in meat quality between animals could be attributed to diet pre-slaughter or carcass fatness. It is concluded that high carcass growth can be achieved on a grass-based diet without a deleterious effect on meat quality.