Cognitive spatial processing and the regulation of posture.

Investigated the interaction between postural regulation and spatial processing by having 24 college students perform L. R. Brooks's (see record 1968-04936-001) spatial and nonspatial memory tasks either while sitting or while maintaining a difficult standing balance position. The balance task disrupted spatial but not nonspatial memory performance. Balance steadiness during spatial and nonspatial memory conditions did not differ. Results suggest that cognitive spatial processing may rely on neural mechanisms that are also required for the regulation of posture. Findings support the idea that spatial processing may rely on phylogenetically older systems. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concentration effect of <Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide on viscoelastic properties of hydrosoluble thermo-thickening copolymers

In this work, we described the preparation of hydrosolubles thermosensitive copolymers obtained via free radical polymerization in aqueous media. The reactions were carried out under different molar ratio of acrylamide and N-isopropylacrylamide (NIPAM) and are considered [80]/[20], [60]/[40], [50]/[50], [40]/[60] and [20]/[80], respectively. The initial concentration of monomer mixture was kept at 3% (weight) based on the water volume. The polymerizations were performed at 70 °C under mechanical agitation during 7 h and the molar ratio between monomer and initiator (4,4′-azobis cyano pentanoic acid) was kept at 0.07%. The copolymers were characterized and results demonstrated that the monomer concentrations were closed to previously feed to the reaction. The turbidity point rises according to the quantity of poly(acrylamide), PAM, incorporated into the copolymers (composition value). Also, it was observed that the molecular weight of each copolymer decreases when the amount of NIPAM increases. On the other hand, the viscosity of all copolymers growth compared to the increase in the temperature from 25 to 70 °C is observed. Notwithstanding, in the case of copolymer with highest NIPAM concentration (CP5), the viscosity decreases in the temperature range from 60 to 70 °C.     

Revenue monotonicity in deterministic, dominant-strategy combinatorial auctions

In combinatorial auctions using VCG, a seller can sometimes increase revenue by dropping bidders. In this paper we investigate the extent to which this counterintuitive phenomenon can also occur under other deterministic, dominant-strategy combinatorial auction mechanisms. Our main result is that such failures of “revenue monotonicity” can occur under any such mechanism that is weakly maximal—meaning roughly that it chooses allocations that cannot be augmented to cause a losing bidder to win without hurting winning bidders—and that allows bidders to express arbitrary known single-minded preferences. We also give a set of other impossibility results as corollaries, concerning revenue when the set of goods changes, false-name-proofness, and the core.¹     

Properties of new nanocomposite triblock copolymer gels based on expandable graphite

In this work, we investigated the effect of expandable graphite (EG) on the property of triblock copolymer prepared from a poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) imbibed with an EB‐compatible hydrocarbon oil. The rheological properties showed that at a temperature between 30 and 40°C below the gel point, the triblock copolymer gels had a dynamic storage modulus (G′) greater than loss modulus (G‵), thereby indicating that at ambient temperature, a physical network is still present in spite of the addition of nanoparticles. Dynamic rheological measurements of the resultant nanocomposite triblock copolymer gels confirmed that the addition of EG affects the linear viscoelastic properties and maximum operating temperature of the parent triblock copolymer gels. The mechanical properties showed only marginal increase, which can be attributed to the poor dispersion that leads to agglomeration of particle into micrometer size stacks, and thus the particles behave only as inorganic fillers. The morphology and X‐ray diffraction revealed that the EG used to generate nanocomposite triblock copolymer gels is dispersed generally within the swollen copolymer and/or solvent. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Driven interval shift dynamics in sigma-delta modulators and phase-locked loops

In this paper, we show how consideration of the first-order sigma-delta (/spl Sigma//spl Delta/) modulator with sampled periodic input motivates study of the maps known mathematically as driven interval shifts. We derive new results concerning the behavior of these maps, and apply these results to provide new insight into the behavior of /spl Sigma//spl Delta/ modulators and phase-locked loops. We will see that viewing these systems through the mechanism of the driven interval shift allows us to identify common features in their behavior.     

Some mechanistic aspects of a nickel-catalyzed electrochemical cross-coupling between aryl halides and substituted chloropyridazines

The nickel-2,2′-bipyridine catalyzed electrochemical cross-coupling reaction between an aryl halide and a chloropyridazine was investigated by an electrochemical study. The electrochemical behavior of the divalent nickel complex is affected by the presence of pyridazine rings which act as co-ligands of nickel. Cyclic voltammetry indicates that the cross-coupling reaction involves first a rapid oxidative addition of the chloropyridazine on the electrogenerated zerovalent nickel complex. The coupling product is then obtained by reaction with the aryl halide.     

Effects of hydrologic infrastructure on flow regimes of California's Central Valley rivers: Implications for fish populations

Alteration of natural flow regimes is generally acknowledged to have negative effects on native biota; however, methods for defining ecologically appropriate flow regimes in managed river systems are only beginning to be developed. Understanding how past and present water management has affected rivers is an important part of developing such tools. In this paper, we evaluate how existing hydrologic infrastructure and management affect streamflow characteristics of rivers in the Central Valley, California and discuss those characteristics in the context of habitat requirements of native and alien fishes. We evaluated the effects of water management by comparing observed discharges with estimated discharges assuming no water management (‘full natural runoff’). Rivers in the Sacramento River drainage were characterized by reduced winter–spring discharges and augmented discharges in other months. Rivers in the San Joaquin River drainage were characterized by reduced discharges in all months but particularly in winter and spring. Two largely unaltered streams had hydrographs similar to those based on full natural runoff of the regulated rivers. The reduced discharges in the San Joaquin River drainage streams are favourable for spawning of many alien species, which is consistent with observed patterns of fish distribution and abundance in the Central Valley. However, other factors, such as water temperature, are also important to the relative success of native and alien resident fishes. As water management changes in response to climate change and societal demands, interdisciplinary programs of research and monitoring will be essential for anticipating effects on fishes and to avoid unanticipated ecological outcomes. Published in 2009 by John Wiley & Sons, Ltd.     

Computational prediction of nucleic acid secondary structure: Methods,applications, and challenges

RNA molecules are crucial in different levels of cellular function, ranging from translation and regulating genes to coding for proteins. Additionally, nucleic acids (RNA and DNA molecules) are designed for novel applications in biotechnology. Understanding the structure of a molecule is important in inferring its function, and computational methods for structure prediction have captured the interest of many researchers.Some functions of RNA molecules in cells, such as gene regulation, result from the binding of one RNA molecule to another, so-called target RNA molecule. This has led to recent interest in prediction of the secondary structure formed from interacting molecules. In this paper, we provide a brief overview of methods, applications, and challenges in computational prediction of nucleic acid secondary structure, both for single strands and for interacting strands.     

Evaluation of 2-way Iraqi Arabic–English speech translation systems using automated metrics

The Defense Advanced Research Projects Agency (DARPA) Spoken Language Communication and Translation System for Tactical Use (TRANSTAC) program (http://1.usa.gov/transtac) faced many challenges in applying automated measures of translation quality to Iraqi Arabic–English speech translation dialogues. Features of speech data in general and of Iraqi Arabic data in particular undermine basic assumptions of automated measures that depend on matching system outputs to reference translations. These features are described along with the challenges they present for evaluating machine translation quality using automated metrics. We show that scores for translation into Iraqi Arabic exhibit higher correlations with human judgments when they are computed from normalized system outputs and reference translations. Orthographic normalization, lexical normalization, and operations involving light stemming resulted in higher correlations with human judgments.     

Chromium Oxide Reduction from Slag by Silicon and Magnesium

Experimental and theoretical studies were performed in order to estimate the effect of the basicity of the slag as well as the amount of reducing agents on the reduction of chromium oxide from a slag in contact with molten steel at 1600 °C. The aim of this work was to compare the efficiency of magnesium and silicon as reducing agents of Cr₂O₃. The slag system contained CaO, MgO, SiO₂, CaF₂ and Cr₂O₃ together with Fe‐alloys (Fe‐Si or Fe‐Si‐Mg). The maximum Cr yield was about 81% with Fe‐44%Si‐9%Mg and 88% with Fe‐75%Si. That means that the reducing effect of Mg was much better than that of Si. Some experiments were conducted to study the effect of initial Cr in steel on the chromium oxide reduction reaction. Three initial Cr contents were tested (0.15, 2 and 4 mass%). It was found that chrome was partially bound into stable spinel phase MgO·Cr₂O₃ in the final slag. Thermodynamic estimations were made to determine the effect of process temperature, slag basicity and the amount of reducing agents in the slag on the Cr recovery. The efficiency of Cr reducing agents increased in the order: Si, Al, Ca and Mg. The Cr yield increased with slag basicity and amount of reducing agents.