A stacked chalcopyrite thin‐film tandem solar cell with 1.2 V open‐circuit voltage

CuGaSe₂ (CGS) thin films were prepared on tin‐doped indium oxide (ITO) coated soda‐lime glass substrates by thermal co‐evaporation to fabricate transparent solar cells. The films consisted of columnar grains with a diameter of approximately 1 μm. Some deterioration of the transparency of the ITO was observed after deposition of the CGS film. The CGS solar cells were electrically connected in series with Cu(In,Ga)Se₂ (CIGS) solar cells and mechanically stacked on the CIGS cells to construct tandem cells. The tandem solar cell with the CGS cell as the top cell showed an efficiency of 7.4% and an open‐circuit voltage of 1.18 V (AM 1.5, total area). Copyright © 2003 John Wiley & Sons, Ltd.     

Stochastic iteration for a constrained optimization problem

A primal dual method of Kushner and Sanvicente for a constrained optimization problem with convex regression functions is investigated without a priori bounds. For the stochastic approximation sequence almost sure convergence to a random optimal solution and a random Kuhn-Tucker vector is shown, and for the uniqueness case, a functional central limit theorem is given.     

Visual depth preferences of the domestic duckling.

Intensively investigated the domestic duckling's depth perception because of its unusual way of life as both a bird and an aquatic animal. Depth perception on the visual cliff, threshold depth, and sensitivity to a wide variety of waterlike conditions were investigated in 486 Giant White Pekin ducklings. While depth perception on the visual cliff was adequate, the Ss plunged off 6-ft heights without hesitation. Overall, monocular depth perception was somewhat inferior to binocular depth perception. Ss had no special sensitivity to waterlike substances. In general, Ss were careless in the presence of depth situations, too careless to survive in other than a flat or watery environment. It is suggested that a possible flocking factor found when Ss were run in pairs may help offset this. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MOCVD as a dry deposition method of ZnSe buffers for Cu(In,Ga)(S,Se)2 solar cells

ZnSe prepared by metal organic chemical vapor deposition is used as a buffer layer in Cu(In,Ga)(S,Se)₂ solar cells without any utilization of wet chemistry. Cell efficiencies are as good as cells with the conventional CdS buffer. Stability of unencapsulated cells under damp heat conditions is somewhat lower for the alternative buffer. The first stages of photoassisted growth are studied. X‐ray photoemission spectroscopy shows that a continuous layer is formed. Copyright © 2004 John Wiley & Sons, Ltd.     

Approximation of Löwdin orthogonalization to a spectrally efficient orthogonal overlapping PPM design for UWB impulse radio

In this paper we consider the design of spectrally efficient time-limited pulses for ultra-wideband (UWB) systems using an overlapping pulse position modulation scheme. For this we investigate an orthogonalization method, which was developed in 1950 by Löwdin [1] and [2]. Our objective is to obtain a set of N orthogonal (Löwdin) pulses, which remain time-limited and spectrally efficient for UWB systems, from a set of N equidistant translates of a time-limited optimal spectral designed UWB pulse. We derive an approximate Löwdin orthogonalization (ALO) by using circulant approximations for the Gram matrix to obtain a practical filter implementation as a tapped-delay-line [7]. We show that the centered ALO and Löwdin pulses converge pointwise to the same square-root Nyquist pulse as N tends to infinity. The set of translates of the square-root Nyquist pulse forms an orthonormal basis for the shift-invariant-space generated by the initial spectral optimal pulse. The ALO transformation provides a closed-form approximation of the Löwdin transformation, which can be implemented in an analog fashion without the need of analog to digital conversions. Furthermore, we investigate the interplay between the optimization and the orthogonalization procedure by using methods from the theory of shift-invariant-spaces. Finally we relate our results to wavelet and frame theory.     

Increased HLA-DQ2-affinity of a synthetic gliadin peptide by acid-induced deamidation of glutamine residues

Presentation of antigenic gliadin peptides by the HLA-DQ2 molecule is considered as a key event in celiac disease pathogenesis. Chemical deamidation of the side chains of glutamine residues might have a strong influence on gliadin peptide binding to the DQ2 molecule. Glutamine deamidation of A-gliadin peptide (45-56) under acidic conditions corresponding to the gastric environment was studied using RP-HPLC, Edman degradation, capillary electrophoresis and electrospray mass spectrometry. Deamidation resulted in peptides with increased DQ2-affinities as assessed in a cell-free binding assay.     

Rapid thermal magnetic annealing as an emerging technology in field-annealing of thin magnetic films for recording heads

An emerging field where rapid thermal processing (RTP) is now rapidly finding its first acceptance is in the industrial manufacturing of thin-film head devices for magnetic recording. Here soft-magnetic thin-film flux guide structures (usually composed of high-moment alloys containing iron, etc.) are applied onto ceramic substrate wafers (such as Al₂O₃–TiC) of sizes up to 150 mm and subsequently ‘activated' by heating and cooling in a magnetic field.We assessed the advantages of rapid thermal magnetic annealing (RTMA) in a new prototype reactor with an external electromagnet, capable of generating an extremely homogeneous magnetic field of 660 Oe (52.8 kA/m) with field lines parallel across the entire wafer area (150 mm in diameter). Samples with 1 μm thick amorphous iron-alloy layers (Fe₇₇Nb₁₁N₁₀Si₂) sputter-deposited onto ceramic substrates of single-crystalline GGG-garnet (Gd₃Ga₅O₁₂) were conventionally annealed and RTMA-annealed in N₂/H₂ at temperatures between 550 and 700°C. Structural analysis by transmission electron microscopy (TEM) and electron diffraction showed that the enhanced performance of the RTMA-annealed layers is due to the different nanocrystallization kinetics induced by the fast heating and cooling rates of RTMA.The ceramic substrate materials normally used in head manufacturing (such as Al₂O₃–TiC) have favorable grey-body properties with high emissivity (≥0.7) over a wide range of temperatures (25–700°C) and wavelengths (1.5–10 μm), which excludes the difficulties encountered in pyrometric temperature control of infrared-transparent substrates such as silicon. We conclude that RTMA yields superior soft-magnetic materials, where throughput numbers of ≥30 wafers/h are possible.     

Effect of visual deprivation on depth discrimination of hooded rats.

In a study with hooded rats (N = 530), Ss raised in the dark were compared to light-reared controls. 21-day-old dark-reared (DR) Ss were not different from controls in the discrimination of 4-in depths, but 30-day-old DR Ss were deficient. 60-day-old DR Ss were deficient in discriminating 4-, 6-, and 8-in depths. 30-day-old DR Ss recovered the loss in depth discrimination after 48 hrs in the light. 60-day-old DR Ss had no noticeable recovery to the 4-in depth discrimination, but they did recover discrimination of the 6-in depth after 72 hrs in the light. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling of storage properties of higher-level languages

The role of storage in the characterization of higher-level programming languages is discussed. Assignment, in particular, has significantly different meaning in different languages, which can hardly be understood without reference to an underlying model of storage. A general storage model is sketched which can be specialized to a model of ALGOL 68 or of PL/I storage. The same model is used to discuss language features allowing highly flexible data structures.Revised version of a paper presented at the ACM Symposium on Data Structures in Programming Languages, University of Florida, Gainesville, February 25–27, 1971.