Soil characteristics of mountainous northeastern Nevada sagebrush community types

Soil physical and chemical properties were studied to identify habitat differences among 15 sagebrush dominated plant community types of the Great Basin. The sagebrush taxa studied followed an apparent gradient of increasing soil fertility, with Artemisia nova commonly occupying the lowest fertility sites. Sites of moderate soil fertility tended to support A. arbuscula , A. longiloba , and A. tridentata ssp. Wyomingensis . Artemisia tridentata ssp. Tridentata and A. tridentata ssp. Vaseyana were commonly found on sites with the highest soil fertility levels as indicated by maximum organic carbon, nitrogen, and phosphorus levels within such soils. Mollic epipedon depth, total depth, and water-holding capacity of the soil also increased as the dominant sagebrush taxon of a community type changed from A. nova to A. tridentata ssp. Vaseyana . Data from this study provide information concerning soil relationships within relatively undisturbed rangeland communities. Such data are required if future soil sampling efforts within the Great Basin are to have a basis for comparison.     

Range Extension and Channel Capacity Increase in Impulse-Radio Ultra-Wideband Communications

We theoretically analyze the channel capacity of a 5th-order Gaussian pulse-based ultra-wideband (UWB) system and experimentally demonstrate 2 Gbit/s UWB-over-fiber transmission systems incorporating wireless transmission. Both electrical and photonic UWB pulse generation methods are employed and its performance is compared. By utilizing optimum UWB pulse design and employing a digital signal processing (DSP) receiver, a bit-error-rate above the forward error correction (FEC) limit for 8 meters of wireless ...     

Interference of hydrazine derivatives with the tyrosinase-tyrosine reaction]

A comparative study of the tyrosinase-tyrosine reaction, using both oxygen-consumption determination and spectrophotometric methods, shows that hydrazine derivatives inhibit melaninogenesis at different steps.     

Carbohydrates as templates for control of distance-geometry in de novo-designed proteins

An understanding of very complex natural systems can often only be achieved through detailed studies of systems with a reduced complexity. Thus, de novo design of proteins allows the study of fundamental forces determining protein folding and stability, as well as protein-protein interactions, by analyses of protein models of structural motifs. In addition, de novo design may lead to new biomimetic molecules with novel properties. In a synthetic approach to achieve structural economy, rigid templates, sometimes called topological scaffolds, have been used to connect secondary-structure elements, most notably alpha-helices. By positioning the helices on the template, the unfavorable entropy of protein folding is reduced. In a novel class of chimeric molecules called carboproteins, carbohydrates are used as templates for de novo design of protein models. Recently, a strategy relying on chemoselective ligation of C-terminal peptide aldehydes to tetra-aminooxy functionalized monosaccharides has provided 7-kDa 4-alpha-helix bundle carboproteins.     

A synthetic peptide that is a bombesin receptor antagonist

The tetradecapeptide bombesin was originally isolated from frog skin. Bombesin-like peptides have since been detected in mammalian gastrointestinal tract, brain and lung. These peptides have potent pharmacological effects on the central nervous system; they cause contraction of intestinal, uterine and urinary tract smooth muscle; and stimulate the release of other peptides including gastrin, cholecystokinin, motilin, pancreatic polypeptide, neurotensin, insulin, enteroglucagon, prolactin and growth hormone. Specific plasma membrane receptors for bombesin have been demonstrated on pancreatic acinar cells, brain membranes and pituitary cells. Studies defining the physiological importance of bombesin have been impeded by the lack of a bombesin receptor antagonist. Here we describe experiments which demonstrate that a peptide originally described as a substance P receptor antagonist, [D-Arg, D-Pro, D-Trp, Leu ]substance P, is also a bombesin receptor antagonist. This peptide competitively inhibits the ability of bombesin to stimulate enzyme secretion from dispersed pancreatic acini, and also inhibits the action of other peptides that interact with the bombesin receptor.     

Evolutionary implications of different types of microbial enzymology for L-tyrosine biosynthesis.

Several patterns of enzymology for L-tyrosine biosynthesis exist in modern microorganisms, each differing in the apparent degree of regulatory efficiency. The extent of pathway evolution in a particular organism may reflect the relative selective pressure for regulation encountered in different ecological niches.