Adult age comparisons in the processing of event frequency information.

The usual superiority in frequency-of-occurrence judgments of younger vs older subjects was hypothesized to result from greater strategic encoding of the materials conveying frequency information. A subject-paced, visual search task was designed to control nontarget word encoding. Relative frequency judgments for the nontarget word pairs were equally accurate for younger and older subjects, and performance of both groups was above chance. Results suggest that strategic cover-task encoding can induce age differences in incidental frequency processing. Consistent with a nonoptimal as opposed to an optimal view, automatic processes require only minimal capacity for above-chance performance, but additional strategic resources can increase performance. When such additional resources are used more by younger than by older subjects, the former are better in frequency performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

University professors' views of knowledge and validation processes.

Professors in 6 matched pure and applied fields of study were interviewed to determine the validation processes and truth criteria used in their disciplines. Differences across disciplines were found in the validation processes and in the importance placed on conceptual frameworks or models. Use of empirical evidence was more important in the natural and social sciences; peer review was more important in the humanities. Professors in pure fields of study were more likely to use conflicting evidence or counterexamples in validating their work than were professors in applied fields. The results suggest that different fields of study operate according to different sets of rules. An important part of university instruction is to provide students with a sense of what these rules are and how they affect learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender-related traits and helping behaviors.

Explored the relation between gender-related instrumental and expressive traits and bystander intervention. 91 male and 83 female undergraduates participated in either a 2- or a 4-person group discussion, carried on via an intercom, during which one of the purported participants (18 undergraduate confederates served) supposedly fainted and fell to the floor. Relationships were determined between helping behavior and scores on the M (instrumentality) and F (expressiveness) scales of the Personal Attributes Questionnaire. In both experimental conditions, men high in instrumentality were less likely to respond than low-scoring men, thus replicating findings obtained by D. M. Tice and R. F. Baumeister (see record 1986-01161-001) with a group of men and women. A high degree of expressiveness in men was also associated with lesser responding. These results were contrary to those reported by P. Senneker and C. Hendrick (see record 1984-12171-001), who found with a group of women that instrumentality facilitated helping behaviors. Nonsignificant results were found in females, but the trends were in the same direction as those reported by Senneker and Hendrick. A theoretical analysis integrating these disparate findings is presented. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk factors and outcome of human immunodeficiency virus-infected patients with sporadic multidrug-resistant tuberculosis in New York City

The discovery of neuroendocrine differentiation in hormone-refractory prostatic adenocarcinoma has opened a potentially new therapeutic approach in this group of patients with a poor prognosis and few effective therapy modalities. Based on previous findings of increased uptake of 11C-5-hydroxytryptophan (11C-5-HTP) in neuroendocrine tumours using the PET technique, this tracer was applied in the study of 10 patients with metastatic hormone-refractory prostatic adenocarcinoma. In three patients, the study was repeated after treatment. An increased uptake of 11C-5-HTP was observed in all investigated skeletal lesions, although the magnitude of the uptake was moderate. The difference between the standard uptake values (SUV) in normal bone and metastatic lesions was significant (p < 0.001). A kinetic analysis of the uptake of 11C-5-HTP demonstrates an increase during the first minutes followed by a wash-out and a stabilization of the tissue/blood ratio at about 2. The Patlak plots demonstrated a gradual increase in the transport rate during the first 20 to 30 min, after which a constant level was observed. The SUV varied between patients and between lesions over time and treatment. The uptake of 11C-5-HTP discriminates metastatic lesions from normal bone and may thus aid in the diagnosis and, potentially, in treatment monitoring of metastatic hormone-refractory prostatic adenocarcinoma. Uptake kinetics are characterized by a wash-out and cannot alone be used as proof of neuroendocrine differentiation in hormone-refractory prostatic adenocarcinoma.     

Young adults' immediate and delayed reactions to simulated marital conflicts: Implications for intergenerational patterns of violence in intimate relationships.

This study investigated the thoughts and feelings that young adults from violent (VPA) and nonviolent (NPA) interparental-conflict backgrounds reported while listening to simulated marital conflicts and after a delay for reflection. While listening to conflicts, VPAs were more likely than NPAs to predict negative outcomes and to place blame. No between–groups differences regarding negative outcomes emerged after a delay. VPAs also reported perpetrating and experiencing more aggressive conflict in their dating relationships. Post hoc probes revealed that the negative-outcome-prediction and blaming variables played no significant mediating role in participants' intergenerational patterns of intimate-relationship aggression; however, methodological limitations likely compromised the statistical power for examining this mediational model. Results are discussed in light of research regarding intergenerational patterns of violence within families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Novel Processing Route to Control Grain Growth in Submicrometer Alumina Compacts

A novel processing procedure for significantly suppressing grain growth in submicrometer alumina compacts has been developed and implemented with the intent of ultimately using the same processing route to control grain size in nanophase alumina compacts. In this study, partially sintered alumina pellets made from 0.5 µm starting powders are altered by the chemical infiltration of Si₃N₄. The control and infiltrated pellets are then heated to 1650°C for 4 h. The fully sintered pellets are approximately 97% dense. Suppressed grain growth is observed in the infiltrated pellets. The average grain size in the control pellets after densification is 4.2 and 1.2 µm in the infiltrated pellets. Depth of infiltration is measured using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Depending on the specific infiltration conditions used, the outer 15-50% of the infiltrated pellets exhibit a graded microstructure consisting of a region of abnormal grain growth and a region of suppressed grain growth. Abnormal grain growth is visible on the outer surfaces of the infiltrated pellets where a relatively high ratio of Si to N is present. Further into the pellet, after some depletion of the Si source gas has occurred, regions of suppressed grain growth are apparent. Based on these results, an infiltration profile is determined. A mathematical model is developed to describe the infiltration process and to determine optimal infiltration conditions. High-resolution electron microscopy (HREM), energy dispersive spectroscopy (EDS), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS) are used to study the infiltrated samples.     

Time-resolved cryotransmission electron microscopy

We describe a new technique, time-resolved cryotransmission electron microscopy (TRC-TEM), that can be used to study changes in microstructure occurring during dynamic processes such as phase transitions and chemical reactions. The sample is prepared on an electron microscope grid maintained at a fixed temperature in a controlled atmosphere. The dynamic process is induced on the grid by a change in pH, salt, or reactant concentration by rapid mixing with appropriate solutions. Alternatively, induction is by rapid change of specimen temperature, or by controlled evaporation of a volatile component. We call such procedures on-the-grid processing. The dynamic process is permitted to run for a defined time and then the thin-film specimen is thermally fixed by plunging into liquid ethane at its freezing point, producing a cryotransmission electron microscopy specimen. By repeating this procedure with varying delays between induction and sample fixation, we can observe transient microstructures. We demonstrate the use of TRC-TEM to study the intermediate structures that form during the transitions between Lα, I_II, and H_II liquid crystalline phases in phospholipid systems. We also identify several other possible applications of the technique.     

Surface Roughening and Unstable Neck Formation in Faceted Particles: I, Experimental Results and Mechanisms

Experimental in situ TEM results described by Rankin and Boatner are surprising because they show initial neck formation between two isolated MgO particles, followed by neck rupture. A quantitative assessment of the original images shows that initial neck growth corresponds to material removed from the rounded edges which contact the neck, and that neck rupture transfers material directly from the neck to the adjacent faceted faces. During the initial neck growth process surface diffusion along the rounded edges of the crystals is apparently the dominant mass transport mechanism, and material is not transferred to the faceted faces because of the energy barrier associated with forming a new atomic layer on top of a faceted surface. This energy barrier can apparently be overcome when a curvature reversal at a facet/rough surface boundary creates a step which makes it possible to add one or more new atomic layers to the faceted face(s). This can move material away from the neck, and thus lead to neck rupture.     

Environmentally induced analgesia: Age-related decline in a neurally mediated, nonopioid system.

Two experiments examined the function of an endogenous system of pain inhibition during aging. In Exp I, 80 male Sprague-Dawley rats (aged 3, 14, and 24 mo) were exposed to 90 sec of hindpaw shock. To investigate the pharmacology and anatomy involved in the production of hindpaw shock-induced analgesia, the effects of naltrexone (7 mg/kg), scopolamine (5 mg/kg), and adrenalectomy were examined. Results show that there was an age-related reduction in the degree of analgesia produced by hindpaw shock. Naltrexone and adrenalectomy did not alter the analgesia elicited by hindpaw shock. Scopolamine reduced the analgesia produced by hindpaw shock, and the effectiveness of scopolamine blockage declined with age. Exp II, with 18 3-mo-old and 13 23-mo-old male Sprague-Dawley rats, demonstrated that the effect of scopolamine was specific to the analgesia induced by hindpaw shock because scopolamine was ineffective in modifying the analgesia produced by a different stressor (cold water). It is suggested that the decline in hindpaw shock-induced analgesia is the result of an alteration in the function of the cholinergic system. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)