Traumatic brain injury and memory: The role of hippocampal atrophy.

In traumatically brain-injured (TBI) patients (n?=?83), memory performance was examined on the Warrington Recognition Memory Test, Rey-Osterrieth Complex Figure, and the Logical Memory and Visual Reproduction subtests of the Wechsler Memory Scale-Revised in relationship to time postinjury and structural changes based on MRI volumetry, including hippocampus volume. Significant trauma-induced changes were observed, including hippocampal atrophy. Structure-function relationships generally became significant only after 90 days postinjury. Memory tended to relate more to the degree of hippocampal atrophy, particularly left hippocampus, than to nonspecific indicators such as the temporal horns or the ventricle-to-brain ratio. A stronger relationship with left versus right hippocampus was evident for measures of verbal and supposedly nonverbal memory. These results are discussed with regard to the role the hippocampus may play in a neural system of memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Favorable effects of weak acids on negative-ion electrospray ionization mass spectrometry

Despite widespread use in pharmacokinetic, drug metabolism, and pesticide residue studies, little is known about the factors governing response during reversed-phase liquid chromatography coupled with negative-ion electrospray ionization (ESI(-)) mass spectrometry. We examined the effects of various mobile-phase modifiers on the ESI(-) response of four selective androgen receptor modulators using a postcolumn infusion system. Acetic, propionic, and butyric acid improved the ESI(-) responses of analytes to varying extents at low concentrations. Formic acid suppressed ionization, as did neutral salts (ammonium formate, ammonium acetate) and bases (ammonium hydroxide, triethylamine) under most conditions. Two modifiers (2,2,2-trifluoroethanol, formaldehyde) that produce anions with high gas-phase proton affinity increased ESI(-) responses. However, the concentrations of these modifiers required to enhance ESI(-) response were higher than that of acidic modifiers, which is a phenomenon likely related to their low pK(a) values. 2,2,2-Trifluoroethanol increased response of more hydrophobic compounds but decreased response of a more hydrophilic compound. Formaldehyde improved response of all the compounds, especially the hydrophilic compound with lower surface activity. In summary, these results suggest that an ideal ESI(-) modifier should provide cations that can be easily electrochemically reduced and produce anions with small molecular volume and high gas-phase proton affinity.     

Biogeochemical processes and microbial characteristics across groundwater-surface water boundaries of the Hanford Reach of the Columbia River

Biogeochemical processes within riverbed hyporheic zones (HZ) can potentially impact the fate and transport of contaminants. We evaluated a modified freeze core technique for the collection of intact cobble-bed samples from the Columbia River HZ along a stretch of the Hanford Reach in Washington State and investigated microbiological and geochemical parameters of corresponding frozen and unfrozen samples. During three sampling periods (March, May, and November 2000), relatively high numbers of viable aerobic heterotrophic bacteria were recovered from both unfrozen (10(6)-10(7) cfu/g) and frozen samples (10(5)-10(6) cfu/g). Relatively large populations of sulfate-, nitrate-, and iron-reducing bacteria were present, and significant concentrations of acid-volatile sulfide were measured in some samples, indicating that anoxic regions exist within this zone. Cr(VI), a priority groundwater pollutant on adjacent U.S. Department of Energy lands, was probably removed from solution in HZ samples by a combination of microbial activity and chemical reduction, presumably via products of anaerobic microbial metabolism. These results suggest that biogeochemical processes in the Columbia River HZ may contribute to the natural attenuation of Cr(VI). Although freezing modestly diminished recovery of viable bacteria, freeze core techniques proved reliable for the collection of intact hyporheic sediments.     

Mechanism of Material Removal from Silicon Carbide by Carbon Dioxide Laser Heating

The mechanism of material removal from SiC by CO₂ laser heating was studied using sintered and single-crystal α-SiC. Removal rate and width of the groove showed maxima when plotted as a function of translation speeds. Groove depth decreased as the translation speed of samples increased. Similar results were obtained if argon or air was used as gas assist, which indicated that the material removal mechanism is induced dissociation of SiC. Microstructure of the material deposited in and outside of the groove was studied by SEM. At low scanning speeds, columnar grains 10 to 50 μm long appeared. As the scanning speed increased, columnar grains became smaller and finally only irregular polycrystalline particles were observed. By using Raman spectroscopy, Auger analysis, and X-ray diffraction, phases inside and outside the groove were identified as Si, β-SiC, C, and SiO₂. Columnar grains were identified as β-SiC covered with thin layers of C, Si, and SiO₂. Slow scanning speeds enhanced the growth of β-SiC. At slow scanning speed, free silicon was always found in the grooves of lased single crystals but not in the grooves of lased sintered SiC. It can be concluded that the mechanism of material removal from silicon carbide by CO₂ laser heating is a vaporization process, and material found in the groove and on the surface near the groove is formed by condensation from the vapor.     

A New Nonparametric Growth Model

This paper proposes a new nonparametric reliability growth model for the analysis of the failure rate of a system that is undergoing development test. The only restrictions on the actual, unknown failure distribution for each stage of testing is that it be continuous, have only one unknown parameter ?, and have an associated unimodal likelihood function. No assumptions regarding the parametric form of the failure rate of the development process are made, only that there is no decay in the reliability of the system during the design changes. The parameters are assumed to be ordered from one test stage to the next such that ?1 ? ?2 ? ... ? ?m. The new model performs very well based on relative error and mean square error. The model is generally superior to the popular AMSAA model, regardless of the actual underlying failure process. In addition, the results indicate a notable bias in the AMSAA model, early in the development process, regardless of the actual underlying failure process.     

A social learning model of consultation.

Presents a model of consultation based on A. Bandura's (1977) social learning theory. The philosophical assumptions of the model, which are drawn from reciprocal determinism, are presented, as are the roles and principles that govern this model. The consulting process, which involves relationship building, assessment, problem statement, goal setting, intervention, and evaluation, is also described. Implications of the model for consultants are discussed, an illustrative case vignette is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Public attitudes toward political and technological options for biofuels

This paper explores detailed public attitudes regarding the expanding range of biofuels technologies and policy options. Subjects from 34 in-depth focus groups in central Indiana were fairly knowledgeable about biofuels technologies, but uninformed about biofuels policies despite being from a state where biofuels are a salient political issue. A narrow majority was supportive of biofuels in general, but expressed greater enthusiasm about “second generation” biofuels. Subject beliefs about biofuels’ economic and environmental impacts were most important in shaping these opinions, rather than concerns about energy independence or other issues. In terms of policy options, subjects were most supportive of an alternative fuels standard and least supportive of a fixed subsidy and a cap and trade policy. In contrast to arguments about technologies, participants primarily framed their attitudes toward policies in terms of fairness. Although discussion did not substantially change aggregate preferences for most policies, it did increase support significantly for at least one policy proposal—a variable subsidy for ethanol. It is particularly noteworthy that subjects generally did not support the most common biofuel technology—corn-based ethanol—or the most prominent biofuels policy option—the fixed subsidy—despite residing in a state hosting a strong corn industry and staunch political advocates for both positions.     

ParaGraph: Graph editor support for parallel programming environments

We report here on a graph editor, ParaGraph, that supports massively parallel programming. It provides a flexible mechanism for the concise specification of families of annotated graphs, addressing the problems of user annotation and scale independent graph manipulation. ParaGraph currently serves as the basis for tools supporting communication abstractions in program specification and debugging. Its foundation in an extended form of aggregate rewriting graph grammars makes its adaptation to other parallel programming environments straightforward.The Parallel Programming Environments Project at the University of Massachusetts is supported by the Office of Naval Research under Contract N000014-84-K-0647 and by the National Science Foundation under Grants DCR-8500332 and CCR-8712410.     

LexAGen: An interactive incremental scanner generator

This paper describes LexAGen, an interactive scanner generator which is the first component of an interactive compiler generation environment. LexAGen can generate fast scanners for languages whose tokens can be specified by regular grammars. However, LexAGen also supports several context-sensitive programming language constructs such as nested comments and the interaction between floating-point numbers and the range operator in Modula-2. In addition, LexAGen includes a fast new algorithm for keyword identification. However, the most important and novel aspects of LexAGen are that it constructs scanners incrementally and that specifications can be executed anytime for validation testing. LexAGen specifications are expressed and entered interactively in a restricted BNF format (no left recursion). All syntactic errors and token conflicts are detected and reported immediately as LexAGen incrementally constructs a deterministic finite automaton to represent the scanner. At any time, the user can test the scanner fragment which has been entered by supplying text to be scanned. Alternatively, the user can generate a C-code scanner from the automaton. The generated automaton uses a direct execution approach and is quite fast. LexAGen is implemented in Smalltalk-80. Its extensive use of interactive graphics makes it very easy to use. In addition, the object-oriented paradigm of Smalltalk-80 is the basis for the incremental analysis, the error detection scheme and an intermediate representation which can be easily modified to generate scanners in other target languages such as Pascal, Modula-2 and Ada.