Response-enforcer manipulations in the analysis of blocking/

The effect of prior experience on a current learning task is of the utmost relevance to theories of learning. In special cases, prior experience may even prevent subsequent learning. These cases can generally be thought of as instances of the blocking phenomenon (e.g., Kamin, 1969; Wagner, Logan, Haberlandt, and Price, 1968). Specifically, if a stimulus A is paired with a reinforcer so that a response comes under the control of that stimulus, then when a novel stimulus B is simultaneously compounded with A and also paired with the reinforcer, stimulus B does not acquire control over the response, as measured by presentation of B alone in extinction. Stimulus A is said to block the establishment of stimulus control by B

Mechanisms of negative regulation of protein prenylation: investigation of murine guanylate-binding protein 1

Covalent attachment of isoprenoid lipids to proteins is a post-translational modification that occurs on approximately 2% of all cellular proteins. Proteins that contain a CaaX motif as their final four amino acids are presumed to be targets for the addition of C15 or C20 isoprenoids by farnesyl transferase (FTase) or geranylgeranyl transferase I (GGTase I) respectively. This modification is generally believed to occur stoichiometrically, and irreversibly, in vivo. Thus, if prenylation is to be regulated, this control must occur prior to lipid addition. At the moment, there is little evidence that the enzymatic activity of prenyl transferases can be modulated. Therefore, cellular control over prenylation must occur at the level of protein substrate preference and/or accessibility. Because preventing prenylation of oncogenic proteins such as Ras holds promise as a new area of cancer chemotherapy, there is a great deal of interest in understanding how prenyl transferases recognize their substrates in vivo. In our efforts to better characterize substrate recognition by FTase and GGTase I, we identified a protein termed murine Guanylate Binding Protein-1 (mGBP1) that appeared to naturally limit its own prenylation. Initial studies showed the impairment in mGBP1 modification was more severe for C20 modification, and that non-CaaX amino acids within the C-terminal region of mGBP1 played a role in limiting prenylation. This C20-specific defect appeared to be an intrinsic property of mGBP1, as mutant proteins with C20-type CaaX motifs were poorly prenylated both in vivo and in vitro. However, the C-terminal 18 amino acids of mGBP1 could function as a suitable substrate for prenylation when appended to the K-Ras4B protein, suggesting that the C-terminus required the participation of other mGBP1 structures in order to avoid prenylation. Removal of up to 400 internal amino acids of mGBP1 did not alleviate the block in prenylation, implicating the N-terminal GTP-binding region of mGBP1 as the inhibitory domain. Therefore, mGBP1 may represent a form of previously unrecognized cellular control over prenylation in which an N-terminal nucleotide-binding domain can negatively influence modification of a C-terminal CaaX motif

Generalized Geologic Map for Land-Use Planning: Estill County, Kentucky

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock

Generalized Geologic Map for Land-Use Planning: Hardin County, Kentucky

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock

Biorefinery and Hydrogen Fuel Cell Research

In this project we focused on several aspects of technology development that advances the formation of an integrated biorefinery. These focus areas include: [1] establishment of pyrolysis processing systems and characterization of the product oils for fuel applications, including engine testing of a preferred product and its pro forma economic analysis; [2] extraction of sugars through a novel hotwater extaction process, and the development of levoglucosan (a pyrolysis BioOil intermediate); [3] identification and testing of the use of biochar, the coproduct from pyrolysis, for soil applications; [4] developments in methods of atomic layer epitaxy (for efficient development of coatings as in fuel cells); [5] advancement in fermentation of lignocellulosics, [6] development of algal biomass as a potential substrate for the biorefinery, and [7] development of catalysts from coproducts. These advancements are intended to provide a diverse set of product choices within the biorefinery, thus improving the cost effectiveness of the system. Technical effectiveness was demonstrated in the pyrolysis biooil based diesel fuel supplement, sugar extraction from lignocelluose, use of biochar, production of algal biomass in wastewaters, and the development of catalysts. Economic feasibility of algal biomass production systems seems attractive, relative to the other options. However, further optimization in all paths, and testing/demonstration at larger scales are required to fully understand the economic viabilities. The various coproducts provide a clear picture that multiple streams of value can be generated within an integrated biorefinery, and these include fuels and products

Optimization of the nucleation-site density for the electrodeposition of cadmium sulfide on indium-tin-oxide

Cadmium sulfide (CdS) is a preferred heterojunction partner for a number of chalcogenide-based solar cells. In view of this, interest has grown in the use of solution-based deposition techniques as an alternative route for the preparation of uniform ultrathin films of CdS. However, the quality of the electrodeposited CdS films on indium-tin oxide (ITO) remains far from optimal. This is because the ITO surface is electrochemically heterogeneous due to the presence of indium oxide; nucleation and further electrodeposition of CdS does not transpire on the oxided sites. Hence, only coarse-grained coatings, instead of homogeneous ultrathin films, are generated at un-pretreated ITO surfaces. In the present study, a mitigation of the amount of interfacial In oxide was attempted in order to increase the nucleation-site (indium-metal site) density. The procedure consisted of two steps: (i) Mild electrochemical reduction of the ITO to convert surface In(III) to In(0), followed by (ii) surface-limited redox replacement (SLRR) of In(0) by Cu via an aqueous solution of Cu^(2+). This procedure resulted in the formation of a high density of oxide-free Cu on which CdS nuclei would form; the thickness was such that optical transparency was largely undiminished. A ten-fold increase in CdS site density was observed, and that permitted the epitaxial growth of a second semiconductor, CdTe, atop the CdS film. The influences of applied potential and deposition time on nucleation-site sizes and densities were also studied