Choice between fixed and variable delays with different reward amounts.

Choice between a variable and a fixed food source was studied in pigeons. The variable source yielded different durations of access to food (changed across experimental conditions) uniquely associated with equiprobable delays of either 20 sec or 60 sec, timed from the choice point. A comparison, elapsing alternative (time-left procedure [J. Gibbon and R. M. Church; see PA, Vol 67:2812]), was associated with fixed access to feeder after a 60-sec delay, timed from the beginning of the trial. Preference was best characterized as reflecting an average of the 2 local rates of reinforcement in the variable alternative (the average of the ratio of each standard amount and its associated delay). The averaging rule characterized initial choice link data well, but terminal link responding showed that Ss also remembered the 2 delay–amount combinations separately. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two representational systems in dynamic visual identification.

How does the visual system retain and combine information about an object across time and space? This question was investigated by manipulating the spatiotemporal continuity and form continuity of 2 perceptual objects over time. In Experiment 1 the objects were viewed in central vision within a single eye fixation, in Experiment 2 they were viewed across a saccadic eye movement, and in Experiment 3 they were viewed at different spatial and retinal locations over time. In all 3 experiments some information about the object was found to be linked to its spatiotemporal continuity, and some information was found to be independent of spatiotemporal continuity. Form continuity was found to produce no effect. The results support a theory of dynamic visual identification according to which information is maintained over time by both episodic object representations and long-term memory representations, neither of which necessarily code specific sensory information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Roles of object-file review and type priming in visual identification within and across eye fixations.

Dynamic visual identification was investigated in 4 experiments. In Exps 1 and 2, 2 perceptual objects (2 frames, each containing a letter or 1 containing a letter and the other a plus sign) were previewed in the periphery. A saccade brought these objects to central vision. During the saccade the display was changed so that 1 frame contained a letter and the other a plus sign, and the S identified the letter by naming it aloud as rapidly as possible. In Exp 3, the retinal events of Exps 1 and 2 were simulated. In Exp 4, both the preview and the target were presented centrally within a single fixation. In all experiments both object specific and nonspecific preview benefits were observed. These results support a theory in which the preview benefits observed during visual identification arise from 2 processes, object file review and type priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adolescent psychopathology: II. Psychosocial risk factors for depression.

In a prospective study of adolescent depression, adolescents (N?=?1,508) were assessed at Time 1 and after 1 yr (Time 2) on psychosocial variables hypothesized to be associated with depression. Most psychosocial variables were associated with current (n?=?45) depression. Formerly depressed adolescents (n?=?217) continued to differ from never depressed controls on many of the psychosocial variables. Many of the depression-related measures also acted as risk factors for future depression (n?=?112), especially past depression, current other mental disorders, past suicide attempt, internalizing behavior problems, and physical symptoms. Young women were more likely to be, to become, and to have been depressed. Controlling for the psychosocial variables eliminated the gender difference for current and future but not for past depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Titanium nitride precipitation behavior in thin-slab cast high-strength low-alloy steels

To assess the potential for obtaining and utilizing titanium nitride (TiN) refinement via the increased postsolidification cooling rates associated with thin-slab casting, TiN particle size distributions were evaluated by transmission electron microscope (TEM) examination of carbon extraction replicas. Eight commercially produced thin-slab cast TiN steels, nominally 0.05 pct C, 1.2 pct Mn, and one conventionally cast steel were received. Thin slab samples were taken from three locations in the production process: quenched after casting before the tunnel furnace, quenched after tunnel furnace soaking, and the as-rolled and air-cooled final product. Effects of cooling rate were evident in the results and agree with previously documented behavior, where precipitate size decreases with increased cooling rate. Statistical differences in particle size between specimens from steels with different chemistries were shown. These variations result from differences in the driving force for precipitation, rates of coarsening, and differences in volume fraction due to changes in steel composition. The interaction of composition and processing, such as soaking in the tunnel furnace and rolling, was found to be important. For example, the hyperstoichiometric steel (excess Ti) exhibited fine TiN after casting and soaking, but dramatic coarsening after hot rolling. This behavior was attributed to deformation enhanced particle coarsening, or incomplete precipitation after soaking, followed by continued growth during subsequent processing.     

Measurement of solid fat content by ultrasonic reflectance in model systems and chocolate

A series of confectionery coating fat (CCF) and cocoa butter (CB) dispersions in corn oil were prepared and tempered to a range of temperatures (10, 12 and 15 °C and 26, 27.5 and 29 °C respectively) to produce samples with solid fat contents (SFC) between 0 and 9%. The ultrasonic velocity in the CCF samples increased with increasing SFC and decreased with temperature, however the CB samples were too attenuating to allow velocity measurements. The ultrasonic reflectance at the surface of both sets of dispersions decreased linearly with SFC but at the same level of solids was less for CB than CCF suggesting some dependence on other aspects of fat structure. The microstructures and thermal properties of the fat systems are compared in an attempt to understand these structural differences. Finally ultrasonic reflectance is shown to respond to changes in a chocolate melt during tempering.     

The Appropriation of the Material of Places in the Landscape: the case of tufa and springs

Springs have long been recognized as being significant places in the landscape, and there is ample evidence of later-prehistoric and Roman activity at spring sites. The Christian appropriation of springs as 'places', either indirectly by assigning their origin to saints, or directly by building chapels and churches on spring-head sites, is also well evidenced. The possibility that the material of petrifying springs - tufa - was both transplanted and appropriated, and that the symbolic properties of the material may go back well into British prehistory, is explored.     

Does marital conflict cause child maladjustment? Directions and challenges for longitudinal research.

Although the association between marital conflict and child adjustment problems has been well documented, there is no empirical evidence that conflict actually causes maladjustment. The investigation of causation requires theoretically and empirically informed longitudinal research. Two topics are addressed to facilitate such research. First, how marital conflict may lead to adjustment problems is outlined, with a focus on constructs that are likely to be critical to any theory on this topic. Second, several issues are identified that need to be addressed in longitudinal research on the mechanisms underlying the link between marital and child problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morphological analysis of poly(o-methoxyaniline) thin-films deposited by spin coating technique

Morphological study of conducting polymer thin films obtained by spin coating is reported. Poly(o-methoxyaniline) films were deposited onto glass substrates and analyzed by profilometry and atomic force microscopy (AFM). It is shown that final thickness is correlated by a power law with spin speed with a solution concentration varying coefficient and that surface roughness decreases with increasing spin speed.