GV measurement in the ambulatory setting may allow the detection of healthy elderly people at risk for adverse events. These data may suggest that simple assessment of GV is enough to predict adverse events in well functioning older persons.

The wall structure of the turbulent boundary layer was examined using hot-wire rakes and conditional sampling techniques. Instantaneous velocity measurements indicate a high degree of coherence over a considerable area in the direction normal to the wall. Aty+= 15, there is some evidence of large-scale correlation in the spanwise direction, but almost no indication of the streamwise streaks that exist in the lower regions of the boundary layer. Conditional sampling showed that the normal velocity is directed outwards in regions of strong stream-wise-momentum deficit, and inwards when the streamwise velocity exceeds its mean value. The conditionally averaged Reynolds shear stress was approximately an order of magnitude greater than its conventionally averaged value and decayed slowly downstream.

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A human brainstem cDNA library in bacteriophage Agtll was screened under conditions of reduced hybridization stringency with a leukocyte common antigen (LCA) probe that spanned both conserved cytoplasmic domains. cDNA encoding a receptor-linked protein-tyrosinephosphatase (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48), RPTPase a, has been cloned and sequenced. Human RPTPase a consists of 802 amino acids. The extracellular domain of 150 residues includes a hydrophobic signal peptide and eight potential N-glycosylation sites. This is followed by a transmembrane region and two tandemly repeated conserved domains characteristic of all RPTPases identified thus far. The gene for RPTPase a has been localized to human chromosome region 20pter-20q12 by analysis of its segregation pattern in rodent-human somatic cell hybrids. Northern blot analysis revealed the presence of two major transcripts of 4.3 and 6.3 kilobases. In addition to RPTPase a, two other RPTPases (, and y), identified in the same screen, have been partially cloned and sequenced. Analysis of sequence comparisons among LCA, the LCA-related protein LAR, and RPTPases a, A, and y reveal4 the existence of a multigene family encoding different RPTPases, each containing a distinct extracellular domain, a single hydrophobic transmembrane region, and two tandemly repeated conserved cytoplasmic domains.The degree and pattern of phosphorylation of tyrosine residues on cellular proteins are regulated by the opposing activities of protein-tyrosine kinases (PTKases; ATP:protein-tyrosine O-phosphotransferase, EC 2.7.1.112) and protein-tyrosine-phosphatases (PTPases; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48). The structural characteristics and evolution of PTKases as well as their role in the regulation of cell growth have been considered elsewhere (1, 2). More recently, attention has also been focused on the growing family of PTPases. This family includes two types of molecules: (i) low molecular weight proteins such as PTPase 1B (3, 4), T-cell PTPase (5), and rat brain PTPase (6), which contain a single conserved phosphatase domain, and (ii) high molecular weight, receptor-linked PTPases (RPTPases) containing two tandemly repeated conserved domains separated by 56-57 amino acids. Examples of these include the leukocyte common antigen (LCA), also known as CD45 (7,8)

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Glia maturation factor-beta, a protein found in the brains of all vertebrates thus far examined, appears to play a role in the differentiation, maintenance, and regeneration of the nervous system. Using oligonucleotide probes based on the sequences of three tryptic peptides derived from bovine glia maturation factor-beta, we screened a human brainstem cDNA library in lambda gt11. A 0.7-kb clone was isolated, sequenced in its entirety, and found to encode a polypeptide of 142 amino acids which contained regions identical to the three bovine peptides. This polypeptide, human recombinant glia maturation factor-beta, has been expressed in Escherichia coli and found to possess structural characteristics and biological activity indistinguishable from those of the native bovine protein.

Recently several research groups, including ours, have reported on the deposition of extremely high quality single crystal GaN layers over sapphire substrates. One of the keys to obtaining the high quality was the use of a thin AlN or GaN buffer layer between the sapphire substrate and the grown film. In this communication, we discuss the crystallinity and the influence of the buffer layer in controlling the crystalline, optical, and the electrical properties of the GaN depositions. We also compare the use of GaN and AlN as the buffer layer material. Our results indicate that the buffer layer thickness and the total film thickness are the key factors controlling the electrical, optical, and crystalline properties of the GaN depositions over sapphire substrates.