Fabrication of optically enhanced ZnO nanorods and microrods using novel biocatalysts

We developed a straightforward method to produce hexagonal ZnO nanorods and microrods using a novel biocatalyst, Magnetospirillum magnetotacticum. ZnO nanorods were synthesized homogeneously on growth substrates when the bacterial catalysts were deposited uniformly on substrates whereas ZnO microrods were formed when the catalysts were introduced to selective areas of growth substrates using microcontact printing. X-ray diffraction measurements reveal that these ZnO structures exhibit Wurtzite structures with preferential growth along [0001] direction. Room-temperature photoluminescence spectra of the as-synthesized ZnO nanorods and microrods show extremely strong and sharp UV emission at 390 nm and negligible green emission at 510 nm. Our results demonstrate that Magnetospirillum magnetotacticum is an effective catalyst for the growth of nanometer- and micrometer-sized ZnO structures with exceptionally high-quality optical properties. These defect-free ZnO nano-and micro-materials, when combined with microcontact printing techniques to achieve patterned growth over large areas of substrates, can facilitate their photonic-based applications as optoelectronic devices and chemical/biological sensors.     

Offset invariance in maximum-likelihood decoding for a class ofpartial response channels

In this letter we show that for a class of partial response channels with discrete-time pulse response of the form (1-D)P(D) whose output samples are corrupted by independent samples of additive white Gaussian noise with mean m, a maximum likelihood sequence detector designed for the case of m=0 is also the maximum likelihood sequence detector for an arbitrary value of m. The studied class of partial response channels is widely used for the characterization of digital magnetic recording channels where the DC offset is frequently an issue     

Monte Carlo validation of a multireader method for receiver operating characteristic discrete rating data: factorial experimental design

RATIONALE AND OBJECTIVES: The authors conducted a series of null-case Monte Carlo simulations to evaluate the Dorfman-Berbaum-Metz (DBM) method for comparing modalities with multireader receiver operating characteristic (ROC) discrete rating data. MATERIALS AND METHODS: Monte Carlo simulations were performed by using discrete ratings on fully crossed factorial designs with two modalities and three, five, and 10 hypothetical readers. The null hypothesis was true for all simulations. The population ROC areas, latent variable structures, case sample sizes, and normal/abnormal case sample ratios used in another study were used in these simulations. RESULTS: For equal allocation ratios and small (Az = 0.702) and moderate (Az = 0.855) ROC areas, the empirical type I error rate closely matched the nominal alpha level. For very large ROC areas (Az = 0.961), however, the empirical type I error rate was somewhat smaller than the nominal alpha level. This conservatism increased with decreasing case sample size and asymmetric normal/abnormal case allocation ratio. The empirical type I error rate was sometimes slightly larger than the nominal alpha level with many cases and few readers, where there was large residual, relatively small treatment-by-case interaction and relatively large treatment-by-reader interaction. CONCLUSION: The results suggest that the DBM method provides trustworthy alpha levels with discrete ratings when the ROC area is not too large and case and reader sample sizes are not too small. In other situations, the test tends to be somewhat conservative or slightly liberal.     

Structure of the ankyrin-binding domain of alpha-Na,K-ATPase

The ankyrin 33-residue repeating motif, an L-shaped structure with protruding beta-hairpin tips, mediates specific macromolecular interactions with cytoskeletal, membrane, and regulatory proteins. The association between ankyrin and alpha-Na,K-ATPase, a ubiquitous membrane protein critical to vectorial transport of ions and nutrients, is required to assemble and stabilize Na,K-ATPase at the plasma membrane. alpha-Na,K-ATPase binds both red cell ankyrin (AnkR, a product of the ANK1 gene) and Madin-Darby canine kidney cell ankyrin (AnkG, a product of the ANK3 gene) utilizing residues 142-166 (SYYQEAKSSKIMESFK NMVPQQALV) in its second cytoplasmic domain. Fusion peptides of glutathione S-transferase incorporating these 25 amino acids bind specifically to purified ankyrin (Kd = 118 +/- 50 nM). The three-dimensional structure (2.6 A) of this minimal ankyrin-binding motif, crystallized as the fusion protein, reveals a 7-residue loop with one charged hydrophilic face capping a double beta-strand. Comparison with ankyrin-binding sequences in p53, CD44, neurofascin/L1, and the inositol 1,4,5-trisphosphate receptor suggests that the valency and specificity of ankyrin binding is achieved by the interaction of 5-7-residue surface loops with the beta-hairpin tips of multiple ankyrin repeat units.     

A spatial data handling system for retrieval of images by unrestricted regions of user interest

The Intelligent Data Management (IDM) project at NASA/GSFC has prototyped an Intelligent Information Fusion System (IIFS) that automatically ingests metadata from remote sensor observations into a large catalog. One of the challenges in the implementation of this catalog has been supporting spatially driven searches, where the user has a possibly complex region of interest and wishes to recover those images that overlap all or simply part of that region. A novel spatial data management system that is capable of storing and retrieving records of image data regardless of their source is described. This system has been designed and implemented as part of the IIFS catalog. A new data structure, the hypercylinder, is central to the design. The hypercylinder is specifically tailored for data distributed over the surface of a sphere, such as satellite observations of the Earth or space. Operations on the hypercylinder are regulated by two expert systems. The first governs the ingest of new metadata records, and maintains the efficiency of the data structure as it grows. The second translates, plans, and executes users' spatial queries, performing incremental optimization as partial query results are returned.     

Influence of the Plasma Treatment Regimes on the Surface Morphology and Properties of Films Applied to Steel from Heptane Plasma

Atomic force microscopy, x-ray photoelectron spectroscopy, chemical analysis, and the method of measuring the contact angle were used to reveal the correlation between the surface morphology, physicochemical properties, and texture of films applied to steel by glow discharge in heptane plasma. In the glow zone at low pressure and discharge power, the resulting thin layer is sticky, and its surface has protruding macromolecular conoidal and spheroidal formations. With an increase in the pressure and discharge power, this layer disappears, while the formations become more numerous and then coalesce. The maximum thickness, roughness, and strength of the films and their minimum permeability were found to correlate with the maximum number of the above conoids and spheroids at the film surface. Apparently, they are film growth centers; their formation is caused by the relaxation of internal stresses in the film or lengthy defects in the base metal. In the absence of glow, the sticky film contains no macromolecular formations.     

Acquisition of Ly49 receptor expression by developing natural killer cells

This article focuses on (1) the dimensionality of the caregiving concept; (2) the relation between the identified caregiving dimensions and characteristics of the patient, the caregiver, and their relationship; and (3) the relation between caregiving dimensions and caregiver distress. Findings are based on data from 480 members of the Dutch family organization for patients with schizophrenia/chronic psychosis who completed (1) the Involvement Evaluation Questionnaire (IEQ), which assesses general information (e.g., household characteristics), caregiving, help seeking, coping and distress, and (2) a questionnaire comprising questions on onset and course of the patient's disorder and symptoms characteristic of schizophrenic disorders. Four caregiving domains were found: tension, supervision, worrying, and urging. These domains were strongly related to the patient's symptomatology, contact between the relative and the patient's mental health professional, and the number of hours of mutual contact between the patient and the relative. The connection between patient, caregiver, and relationship variables and the caregivers' distress could be explained substantially by the overall caregiving score. Our findings suggest that caregiving tasks and problems may be diminished and related distress lowered by reducing the patient's symptomatology, increasing relatives' coping capacities, and decreasing the number of contact hours. If distress is reduced, relatives may use less psychotropic medication and may visit their general practitioner less often.