Enhanced coupling of broadband light into amorphous silicon via periodic nanoplasmonic arrays.

Achieving enhanced coupling of solar radiation over the full range of the silicon absorption spectrum up to the bandgap is essential for increased efficiency of solar cells, especially thin film versions. While many designs for enhancing trapping of radiation have been explored, detailed measurements of light scattering inside silicon cells is still lacking. Here, we demonstrate experimentally and computationally that plasmonic-assisted localized and traveling modes can efficiently couple red and infrared radiation into ultrathin amorphous silicon (a-Si) layers. Utilizing patterned periodic arrays of aluminum nanostructures on thin a-Si, we perform specular and diffuse reflectivity and transmission measurements over a broad spectrum. Based on these results, we are able to separate parasitic absorption in aluminum plasmonic arrays from enhanced light absorption in the 200 nm thick amorphous silicon layer, as compared to a blank silicon layer. We discover a very efficient near-infrared a-Si absorption mechanism that occurs at the transition from the radiative to evanescent diffractive coupling, analogous to earlier surface-enhanced infrared studies. These results represent a direct demonstration of enhanced radiation coupling into silicon due to large angle scattering and show a path forward to improved ultrathin solar cell efficiency.

Broadband optical switch based on liquid crystal dynamic scattering.

This work demonstrates a novel broadband optical switch, based on dynamic-scattering effect in liquid crystals (LCs). Dynamic-scattering-mode technology was developed for display applications over four decades ago, but was displaced in favor of the twisted-nematic LCs. However, with the recent development of more stable LCs, dynamic scattering provides advantages over other technologies for optical switching. We demonstrate broadband polarization-insensitive attenuation of light directly passing thought the cell by 4 to 5 orders of magnitude at 633 nm. The attenuation is accomplished by light scattering to higher angles. Switching times of 150 µs to 10% transmission have been demonstrated. No degradation of devices is found after hundreds of switching cycles. The light-rejection mechanism is due to scattering, induced by disruption of LC director orientation with dopant ion motion with an applied electric field. Angular dependence of scattering is characterized as a function of bias voltage.

A pilot trial of a computerized renal template note to improve resident knowledge and documentation of kidney disease.

BACKGROUND: Kidney disease is under-documented in physician notes. The use of template-guided notes may improve physician recognition of kidney disease early in training. OBJECTIVE: The objective of this study was to determine whether a computerized inpatient renal template note with clinical decision support improves resident knowledge and documentation of kidney disease. METHODS: In this prospective study, first year medical residents were encouraged to use the renal template note for documentation over a one-month period. The renal template note included an option for classification of acute kidney injury (AKI) and chronic kidney disease (CKD) categories with a link to standard classifications. Pre- and post-knowledge of AKI and CKD categories was tested with a quiz and surveys of resident experience with the intervention were conducted. Appropriate AKI and/or CKD classification was determined in 100 renal template notes and 112 comparable historical internal medicine resident progress notes from approximately one year prior. RESULTS: 2,435 inpatient encounters amongst 15 residents who participated were documented using the renal template note. A significantly higher percent of residents correctly staged earlier stage CKD (CKD3) using the renal template note compared to historical notes (9/46 vs. 0/33, p<0.01). Documentation of AKI and more advanced CKD stages (CKD4 and 5) did not improve. Knowledge based on quiz scores increased modestly but was not significant. The renal template note was well received by residents and was perceived as helping improve knowledge and documentation of kidney disease. CONCLUSION: The renal template note significantly improved staging of earlier stage CKD (CKD3) with a modest but non-significant improvement in resident knowledge. Given the importance of early recognition and treatment of CKD, future studies should focus on teaching early recognition using template notes with supplemental educational interventions.

Periodically poled BaMgF(4) for ultraviolet frequency generation.

Ferroelectric domain inversion has been demonstrated in BaMgF(4) . Transparency has been measured to <140nm, and no change in transmission was measured under 157-nm irradiation for >1.1x10(9) shots at 2mJ/cm(2) per pulse. First-order quasi-phase-matched generation of 157 nm is predicted by use of grating periods as long as 1.5mum. This material should permit shorter-wavelength chi((2)) frequency-mixing processes than with any other crystalline material.

Excimer-laser-induced degradation of fused silica and calcium fluoride for 193-nm lithographic applications.

We report the initial results of a large-scale evaluation of production-grade fused silica and calcium fluoride to be used in 193-nm lithographic applications. The samples have been provided by many different suppliers of materials. A marathon irradiation chamber permits simultaneous exposure of as many as 36 samples at 800 Hz, at fluences from 0.2 to > or =4 (mJ/cm(2))/pulse and pulse counts in excess of 10(9) . The initial absorption and the laser-induced absorption are found to vary over a wide range. The compaction of each fused-silica sample follows a power law, but its parameters can differ widely from sample to sample.

Spatial pattern of microchannel formation in fused silica irradiated by nanosecond ultraviolet pulses.

We present numerical simulations of propagation of ultraviolet pulses through fused silica using a model that allows for the accumulative action of compaction back on the light. Compaction-induced self-focusing causes the light field to develop into a pattern of hot spots around the incident aperture that correlates with the damage patterns observed during marathon experiments designed to determine the onset of microchannel formation.

Differing proliferative responses in proximal and distal colons of growing rats fed food eaten by adenoma patients.

Animal dietary studies related to human colorectal carcinogenesis are usually based on AIN-76A diet, which is dissimilar to human food in source, preparation, and content. Our aim was to examine colonic epithelial proliferation in rats fed a diet based on the mean daily food intake of adenoma patients. Foods were prepared as reported by the adenoma patients and dehydrated; 64 Sprague-Dawley rats were fed either "human adenoma" or AIN-76A diet and every eight weeks, eight from each group were sacrificed. Both groups gained weight equally, had no colonic histological changes, but during the study showed progressive lengthening of colonic crypts (P < 0.01) and decreased proliferation (P < 0.05) in distal colons. Compared to controls, rats fed human adenoma diet had significantly longer crypts (P < 0.01) and more labeled cells (P < 0.05) at 32 weeks; overall they had increased proliferation (P < 0.01), most significantly in the distal colon. Thus, food eaten by adenoma patients induced hyperproliferative changes in the rat colon during growth and maturity, especially the distal colon, as found in humans at risk for neoplasia.

Confidence and accuracy in trait inference: judgment by similarity.

We examined the confidence and accuracy with which people make personality trait inferences and investigate some consequences of the hypothesis that such judgments are based on similarity or conceptual relatedness. Given information concerning a target person's standing on three global personality dimensions, American and Israeli subjects were asked to estimate the target's self-ratings of 50 trait adjectives and to express their confidence by setting a 90 percent uncertainty range around each estimate. The estimates were positively correlated with the actual ratings obtained from subjects who had evaluated themselves in terms of the 50 traits, but were far too extreme. Furthermore, confidence was negatively correlated with accuracy: People's estimates were most inaccurate and made with greatest certainty when the trait in question was highly similar to the information provided as a basic for judgment. We suggest that intuitive personality judgments overestimate the coherence of the structure underlying trait constructs.

A new dietary model to study colorectal carcinogenesis: experimental design, food preparation, and experimental findings.

Experimental dietary studies of human colorectal carcinogenesis are usually based on the AIN-76A diet, which is dissimilar to human food in source, preparation, and content. The aims of this study were to examine the feasibility of preparing and feeding rats the diet of a specific human population at risk for colorectal neoplasia and to determine whether changes in the colonic morphology and metabolic contents would differ from those resulting from a standard rat diet. The mean daily food intake composition of a previously evaluated adenoma patient case-control study was used for the "human adenoma" (HA) experimental diet. Foods were prepared as for usual human consumption and processed by dehydration to the physical characteristics of an animal diet. Sixty-four female Sprague-Dawley rats were randomized and fed ad libitum the HA or the AIN-76A diet. Every eight weeks, eight rats from each group were sacrificed, and the colons and contents were examined. Analysis of the prepared food showed no significant deleterious changes; food intake and weight gain were similar in both groups. Compared with the controls, the colonic contents of rats fed the HA diet contained significantly less calcium, concentrations of neutral sterols, total lipids, and cholic and deoxycholic acids were increased, and there were no colonic histological changes other than significant epithelial hyperproliferation. This initial study demonstrated that the HA diet can be successfully processed for feeding to experimental animals and is acceptable and adequate for growth but induces significant metabolic and hyperproliferative changes in the rat colon. This dietary model may be useful for studies of human food, narrowing the gap between animal experimentation and human nutritional research.

Probability judgement in medicine: discounting unspecified possibilities.

Research in cognitive psychology has indicated that alternative descriptions of the same event can give rise to different probability judgments. This observation has led to the development of a descriptive account, called support theory, which assumes that the judged probability of an explicit description of an event (that lists specific possibilities) generally exceeds the judged probability of an implicit description of the same event (that does not mention specific possibilities). To investigate this assumption in medical judgment, the authors presented physicians with brief clinical scenarios describing individual patients and elicited diagnostic and prognostic probability judgments. The results showed that the physicians tended to discount unspecified possibilities, as predicted by support theory. The authors suggest that an awareness of the discrepancy between intuitive judgments and the laws of chance may provide opportunities for improving medical decision making.