4,238 research outputs found

    Surface Erosion and Sedimentation Associated with Forest Land Use in Interior Alaska

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    Completion reportThe magnitude of sheet-rill erosion associated with various landscape manipulations is presented. The Universal Soil Loss Equation's usefulness for predicting annual sheet-rill erosion within interior Alaska is confirmed. Investigations of sheet-rill erosion indicate that removing the trees from forested areas with only minor ground cover disturbance did not increase erosion. Removing the ground cover, however, increased erosion 18 times above that on forested areas. Erosion is substantially reduced when disturbed areas are covered with straw mulch and fertilizer. Comparison of the actual erosion and the quantity of erosion predicted with the Universal Soil Loss Equation indicates that the equation overestimates annual erosion by an average of 21 percent. It overestimates individual storm erosion by an average of 174 percent. Data are also presented concerning sheet-rill erosion in a permafrost trail, distribution of the rainfall erosion index, and suggested cover and management factor values.This work was supported by the Institute of Northern Forestry, Pacific Northwest Forest and Range Experiment Station, USDA. The Institute of Water Resources, University of Alaska, provided facilities for this research

    High gradient directional solidification furnace

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    A high gradient directional solidification furnace is disclosed which includes eight thermal zones throughout the length of the furnace. In the hot end of the furnace, furnace elements provide desired temperatures. These elements include Nichrome wire received in a grooved tube which is encapsulated y an outer alumina core. A booster heater is provided in the hot end of the furnace which includes toroidal tungsten/rhenium wire which has a capacity to put heat quickly into the furnace. An adiabatic zone is provided by an insulation barrier to separate the hot end of the furnace from the cold end. The old end of the furnace is defined by additional heating elements. A heat transfer plate provides a means by which heat may be extracted from the furnace and conducted away through liquid cooled jackets. By varying the input of heat via the booster heater and output of heat via the heat transfer plate, a desired thermal gradient profile may be provided

    General purpose rocket furnace

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    A multipurpose furnace for space vehicles used for material processing experiments in an outer space environment is described. The furnace contains three separate cavities designed to process samples of the widest possible range of materials and thermal requirements. Each cavity contains three heating elements capable of independent function under the direction of an automatic and programmable control system. A heat removable mechanism is also provided for each cavity which operates in conjunction with the control system for establishing an isothermally heated cavity or a wide range of thermal gradients and cool down rates. A monitoring system compatible with the rocket telemetry provides furnace performance and sample growth rate data throughout the processing cycle

    Energetics of Shaker K channels block by inactivation peptides

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    A synthetic peptide of the NH2-terminal inactivation domain of the ShB channel blocks Shaker channels which have an NH2-terminal deletion and mimics many of the characteristics of the intramolecular inactivation reaction. To investigate the role of electrostatic interactions in both peptide block and the inactivation process we measured the kinetics of block of macroscopic currents recorded from the intact ShB channel, and from ShB delta 6-46 channels in the presence of peptides, at different ionic strengths. The rate of inactivation and the association rate constants (k(on)) for the ShB peptides decreased with increasing ionic strength. k(on) for a more positively charged peptide was more steeply dependent on ionic strength consistent with a simple electrostatic mechanism of enhanced diffusion. This suggests that a rate limiting step in the inactivation process is the diffusion of the NH2-terminal domain towards the pore. The dissociation rates (k(off)) were insensitive to ionic strength. The temperature dependence of k(on) for the ShB peptide was very high, (Q10 = 5.0 +/- 0.58), whereas k(off) was relatively temperature insensitive (Q10 approximately 1.1). The results suggest that at higher temperatures the proportion of time either the peptide or channel spends in the correct conformation for binding is increased. There were two components to the time course of recovery from block by the ShB peptide, indicating two distinct blocked states, one of which has similar kinetics and dependence on external K+ concentration as the inactivated state of ShB. The other is voltage-dependent and at -120 mV is very unstable. Increasing the net charge on the peptide did not increase sensitivity to knock-off by external K+. We propose that the free peptide, having fewer constraints than the tethered NH2-terminal domain binds to a similar site on the channel in at least two different conformations

    Interactions of amino terminal domains of Shaker K channels with a pore blocking site studied with synthetic peptides

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    Synthetic peptides of the five alternative NH2-terminal sequences of Shaker when applied to the cytoplasmic side of ShB channels that have an NH2-terminal deletion (ShB delta 6-46) block the channel with potencies correlated with the rate of inactivation in the corresponding variant. These peptides share no sequence similarity and yet three out of the five have apparent dissociation constants between 2 and 15 microM, suggesting that the specificity requirements for binding are low. To identify the primary structural determinants required for effective block of ShB delta 6-46, we examined the effects of substitutions made to the 20 residue ShB peptide on association and dissociation rates. Nonpolar residues within the peptide appear to be important in stabilizing the binding through hydrophobic interactions. Substitutions to leucine-7 showed there was a clear correlation between hydrophobicity and the dissociation rate constant (koff) with little effect on the association rate constant (kon). Substituting charged residues for hydrophobic residues within the region 4-8 disrupted binding. Within the COOH-terminal half of the peptide, substitutions that increased the net positive charge increased kon with relatively small changes in koff, suggesting the involvement of long-range electrostatic interactions in increasing the effective concentration of the peptide. Neutralizing charged residues produced small changes in koff. Charges within the region 12-20 act equivalently; alterations which conserved net charge produced little effect on either kon or koff. The results are consistent with this region of the peptide having an extended conformation and suggest that when bound this region makes few contacts with the channel protein and remains relatively unconstrained. Analogous mutations within the NH2-terminal domain of the intact ShB channel produced qualitatively similar effects on blocking and unblocking rates

    MADNESS: Schizophrenia, Then and Now

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    In examining the subject of mental illness, it is clear that diseases and disorders of the brain have not received the same degree of attention in the United States, over the years, as have acute and infectious diseases of the body. This thesis discusses the history of research and treatment of brain disorders, generally, with particular emphasis on schizophrenia, the most serious of mental disorders. The narrative includes the story of my aunt, who was schizophrenic. The objective of this thesis is to add another voice to the many who have asked that the bar on mental health research and treatment be raised significantly. A secondary objective is to include this paper as a chapter in the family memoir I hope to write

    Henri Temianka Correspondence; (aldrich)

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    This collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_correspondence/1012/thumbnail.jp

    The Snipes: A Study of the Genus Capella, by Leslie M. Tuck

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    Geographic variation of bewick wrens in the eastern United States

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