Activation of alcohol expectancies in memory in relation to limb of the blood alcohol curve.

Attempts to understand the mechanism by which alcohol expectancies might influence drinking have related activation of expectancies in memory to alcohol use. Limb of the blood alcohol curve, however, has not been considered. In the present study, 527 undergraduates completed the Anticipated Biphasic Alcohol Effects Scale and a drinking measure. Multidimensional scaling was used to map expectancies into memory network format, and likely activation of expectancies was empirically modeled. Heavier drinkers were most likely to activate positive and arousing expectancies associated with the ascending limb, whereas lighter drinkers were most likely to activate negative and sedating expectancies associated with the descending limb. These findings add to the literature suggesting that activation of expectancies in memory may be an important determinant of drinking behavior and a promising target for intervention strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral Limits of Auditory Temporal Resolution in the Rat: Amplitude Modulation and Duration Discrimination.

Thresholds for detecting the presence of amplitude modulation in a noise carrier were determined for rats using conditioned avoidance procedures. There was a progressive increase in threshold with modulation rates between 5 Hz and 2 kHz. Further tests were conducted to determine difference thresholds for detecting an increase in modulation rate for standard rates of 10, 50, and 100 Hz. The size of the difference threshold increased progressively as the standard rate increased. In addition, thresholds for detecting an increase in the duration of a noise burst were determined for various standard durations. The difference thresholds were constant for values between 10 and 50 ms but increased progressively, with standard durations between 0.1 and 1.0 s. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructural investigation of the oxidation of an Fe-3 pct Cr alloy

The microstructure and microchemistry of the oxide scale on an Fe-3 wt pct Cr alloy have been investigated after oxidation in the temperature range 700 to 800 °C. Transmission and scanning electron microscopy along with energy dispersive X-ray analysis and Auger electron spectroscopy techniques were used for the investigation. Multilayered scales are observed which vary in composition and structure; the innermost oxide is an Fe-Cr spinel of the type Fe(Fe_2•xCr_x)O₄. The intermediate layer and the outer oxide layer are both α-Fe₂O₃ hematite. The outer hematite layer is nonadherent and wrinkling is observed. Spallation occurs readily at the inner hematiteJspinel interface and at the spinel oxideJalloy interface. The poor oxidation resistance of the alloy is discussed in terms of these observations.     

An Ordered Upwind Method with Precomputed Stencil and Monotone Node Acceptance for Solving Static Convex Hamilton-Jacobi Equations

We define a δ-causal discretization of static convex Hamilton-Jacobi Partial Differential Equations (HJ PDEs) such that the solution value at a grid node is dependent only on solution values that are smaller by at least δ. We develop a Monotone Acceptance Ordered Upwind Method (MAOUM) that first determines a consistent, δ-causal stencil for each grid node and then solves the discrete equation in a single-pass through the nodes. MAOUM is suited to solving HJ PDEs efficiently on highly-nonuniform grids, since the stencil size adjusts to the level of grid refinement. MAOUM is a Dijkstra-like algorithm that computes the solution in increasing value order by using a heap to sort proposed node values. If δ>0, MAOUM can be converted to a Dial-like algorithm that sorts and accepts values using buckets of width δ. We present three hierarchical criteria for δ-causality of a node value update from a simplex of nodes in the stencil.     

Satellite remote sensing of surface oceanic fronts in coastal waters off west-central Florida

Two algorithms designed to detect deepwater oceanic features and arbitrary edge profiles were tuned to automatically delineate fronts in coastal waters off west-central Florida using satellite-derived sea surface temperature (SST), chlorophyll-a concentration (Chl), normalized water-leaving radiance (nL_w), and fluorescence line height (FLH) images during select periods in the spring and fall of 2004 and 2005. The dates correspond to recreational king mackerel, Scomberomorus cavalla, tournaments. A histogram-based algorithm was useful to detect coastal surface SST, nL_w, and FLH fronts, specifically. A gradient-based algorithm, with a smaller kernel box of 3 × 3 pixels, best identified nearshore (< 10 m depth) features in Chl images at the mouth of Tampa Bay, but was less effective for fronts farther offshore where gradients were weaker. Local winds and tide levels estimated from a coastal observing buoy, and bathymetric gradients were examined to help understand the factors that influenced front formation and stability. Periods of strong and variable winds led to front movement of up to 10 km per day or dissipation within 2-3 days in over 80% of the fronts detected in SST, Chl, nL_w, and FLH imagery. Short episodes of less variable wind velocities typically led to more stable and stationary fronts, within 3-5 km, for up to four days. The occurrence of fronts closely associated with the coastal bathymetry, namely at the 20 m and 30 m isobaths, was significantly higher in the fall SST imagery and in the spring Chl imagery. Fall SST fronts related to bathymetric gradients likely resulted from progressive cooling of the water with depth. Stronger Chl and nL_w443 gradients at the mouths of estuaries in the fall compared to the spring were attributed to increased precipitation and periods of stronger winds or tides. The FLH imagery was most useful in delineating coastal algal blooms. The automatic front detection techniques applied here can be an important tool for resource managers to track coastal oceanographic features daily, over synoptic spatial scales.     

Person perception in heterogeneous groups.

Conducted 2 experiments to examine the implications of gender and race salience for person organization and recall. Exp I examined the facilitating effects of group heterogeneity on categorization of social information during encoding. Exp II examined the effects of heterogeneity on the organization of information in retrieval. 24 undergraduates in Exp I and 32 undergraduates in Exp II were presented with verbal information and photographs describing groups differing in racial and sexual composition. Some of the groups were composed of members of the same gender and race (homogeneous groups), and other groups were racially and sexually mixed (heterogeneous groups). Ss in Exp I were required to sort the information sets by person, whereas Ss in Exp II were asked to read and recall the information sets. Analyses of sorting speed, person clustering, and total recall revealed the facilitating effects of race and gender salience. This was true even though the information was independent of the race and gender stereotypes. Overall results suggest that group heterogeneity resulted in increased person organization. Findings from Exp II establish that group heterogeneity was associated with increased recall. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inference-based retrospective revaluation in human causal judgments requires knowledge of within-compound relationships.

In an allergist causal-judgment task, food compounds were followed by an allergic reaction (e.g., AB+), and then 1 cue (A) was revalued. Experiment 1, in which participants who were instructed that whatever was true about one element of a causal compound was also true of the other, showed a reverse of the standard retrospective revaluation effect. That is, ratings of B were higher when A was causal (A+) than when A was safe (A-). This effect was taken to reflect inferential reasoning, not an associative mechanism. In Experiment 2, within-compound associations were found to be necessary to produce this inference-based revaluation. Therefore, evidence that within-compound associations are necessary for retrospective revaluation is consistent with the inferential account of causal judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Minimum-Area Hulls

We study some minimum-area hull problems that generalize the notion of convex hull to star-shaped and monotone hulls. Specifically, we consider the minimum-area star-shaped hull problem: Given an n -vertex simple polygon P , find a minimum-area, star-shaped polygon P ^* containing P . This problem arises in lattice packings of translates of multiple, nonidentical shapes in material layout problems (e.g., in clothing manufacture), and has been recently posed by Daniels and Milenkovic. We consider two versions of the problem: the restricted version, in which the vertices of P ^* are constrained to be vertices of P , and the unrestricted version, in which the vertices of P ^* can be anywhere in the plane. We prove that the restricted problem falls in the class of ``3sum-hard' (sometimes called ``n ² -hard') problems, which are suspected to admit no solutions in o(n ² ) time. Further, we give an O(n ² ) time algorithm, improving the previous bound of O(n ⁵ ) . We also show that the unrestricted problem can be solved in O(n ² p(n)) time, where p(n) is the time needed to find the roots of two equations in two unknowns, each a polynomial of degree O(n) . We also consider the case in which P ^* is required to be monotone, with respect to an unspecified direction; we refer to this as the minimum-area monotone hull problem. We give a matching lower and upper bound of Θ(n log n) time for computing P ^* in the restricted version, and an upper bound of O(n q(n)) time in the unrestricted version, where q(n) is the time needed to find the roots of two polynomial equations in two unknowns with degrees 2 and O(n) . Received November 1996; revised March 1997.     

Anterior cingulate activity and level of cognitive conflict: Explicit comparisons.

The role of anterior cingulate cortex (ACC) in attention is a matter of debate. One hypothesis suggests that its role is to monitor response-level conflict, but explicit evidence is somewhat lacking. In this study, the activation of ACC was compared in (a) color and number standard Stroop tasks in which response preparation and interference shared modality (response-level conflict) and (b) color and number matching Stroop tasks in which response preparation and interference did not share modality (non-response-level conflict). In the congruent conditions, there was no effect of task type. In the interference conditions, anterior cingulate activity in the matching tasks was less than that in the standard tasks. These results support the hypothesis that ACC specifically mediates generalized modality-independent selection processes invoked by response competition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The thermochemistry of magnesium in nickel-base alloys: Part II. activity of magnesium

The experimental method described in Part I^[49] of this article was applied to the liquid nickel-magnesium system for the determination of magnesium activity. From a practical point of view, knowledge of the thermodynamic properties of magnesium is becomming increasingly important as the control of processing parameters tightens. Magnesium is added to nickel-base alloys for improved ductility, at levels typically less than 100 parts per million (ppm). Thus, experimental results presented are applicable to levels of less than 100 ppm Mg. The following parameters were determined: the equilibrium constant for the formation of spinel, the magnesium-oxygen and aluminum-oxygen interaction coefficients, the equilibrium constant for solution of magnesium in liquid nickel, and the Raultian activity coefficient of magnesium in an infinitely dilute solution. Formerly Graduate Student, University of British Columbia