Behavioral and physiological reactions to observed violence: Effects of prior exposure to aggressive stimuli.

80 male undergraduates first watched videotaped sequences that were arousing, but which contained different degrees of violence. Ss then observed either a 2nd videotape of a sequence of aggressive acts or no videotape. Ss who were shown the 2nd videotape were told that the aggressive acts they saw were either justified or not justified, or were given no information regarding justification. It was found that Ss who had first seen an arousing but less violent tape were subsequently more aggressive toward an antagonist if they had observed justified violence. Ss who had first watched the violent videotape showed no differences in aggression as a function of the justification of the 2nd set of aggressive acts. Analysis of blood pressure data showed that prior exposure to violence attenuated arousal in response to subsequently observed aggression. The results are discussed in terms of differential sensitivity to cues that inhibit or disinhibit aggression. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction to the special issue on the self and social identity.

This article describes the special issue of the Journal of Personality and Social Psychology (JPSP), which is the result of a joint undertaking by the three sections of JPSP. This makes it different from previous special sections or issues of the journal in that rather than relying on the generous services of a guest editor, the same editorial team that handles the regular journal issues has originated this special issue, as well, thus conveying a sense of "business as usual." Our major reason for the present initiative was to highlight the essential unity of personality and social psychology as a field of science. The topic choice for the present special issue was dictated by its relevance and interest to the field of personality and social psychology as a whole, across its various partitions and subdivisions. The articles in the special issue amply reflect the naturalness with which the self and social identity theme transcends the boundaries of JPSP sections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

XAS study of iron and arsenic speciation during Fe(II) oxidation in the presence of As(III)

The speciation of As and Fe was studied during the oxidation of Fe(II)-As(III) solutions by combining XAS analysis at both the Fe and As K-edges. Fe(II) and As(III) were first hydrolyzed to pH 7 under anoxic conditions; the precipitate was then allowed to oxidize in ambient air for 33 h under vigorous stirring. EXAFS analysis at the As K-edge shows clear evidence of formation of inner-sphere complexes between As(III) and Fe(II), i.e., before any oxidation. Inner-sphere complexes were also observed when Fe became sufficiently oxidized, in the form of edge-sharing and double-corner linkages between AsIIIO3 pyramids and FeIIIO6 octahedra. XAS analyses at the Fe K-edge reveal that the presence of As(III) in the solution limits the polymerization of Fe(II) and the formation of green rust and inhibits the formation of goethite and lepidocrocite. Indeed, As(III) accelerates the Fe(II) oxidation kinetics and leads to the formation of nanosized Fe-As subunits of amorphous aggregates. These observations, rather than a presumed weaker affinity of As(III) for iron oxyhydroxides, might explain why As(III) is more difficult to remove than As(V) by aerating reducing groundwater.     

Removal of methylated arsenic in groundwater with iron filings

Field and laboratory experiments were conducted to study the potential use of Fe filings to remove monomethyl arsenate (MMA) and dimethyl arsenate (DMA) from contaminated waters. Batch experiments show that the affinity of MMAfor Fe filings is comparable to that of inorganic arsenate, but lower than that for arsenite. In contrast, very little DMA was retained by Fe filings or their corrosion products. The wide range of affinities of different As species for Fe filings was confirmed by a series of retention and selective-leaching experiments using small columns and As-spiked groundwater. The effectiveness of Fe filings was also demonstrated with a field deployment at a U.S. Superfund site where groundwater is highly contaminated with both organic and inorganic As species. Over the course of 4 months, a 3 L cartridge of Fe filings removed > 85% of As contained in 16000 L of groundwater containing 1-1.5 mg/L total dissolved As, approximately 30% of which was organic As. The results indicate that Fe filings could be used to treat groundwater contaminated with MMA, which is the main organic form of As at most contaminated sites. Indications of partial demethylation in the column of Fe filings suggest conditions might be optimized further to enhance the removal of DMA.     

Role of cognitive€motional mediators and individual differences in the effects of media violence on aggression.

Two experiments were conducted to test the hypothesis that observation of media violence elicits thoughts and emotional responses related to aggression. In Experiment 1, highly violent videotapes elicited more aggressive cognitions than did a less violent tape. This effect was moderated by the trait of stimulus screening. In Experiment 2, aggressive cognitions increased with the level of violence in the videotape, and physical assaultiveness influenced this effect. Hostility and systolic blood pressure were higher in response to the most violent video than in response to the other two. Hostility was influenced by emotional susceptibility and dissipation–rumination, and systolic blood pressure was influenced by emotional susceptibility and assaultiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-directed aggression and similarity between frustrator and aggressor.

Under the guise of a learning experiment, 33 male undergraduates were arbitrarily given a number of electric shocks by an experimental confederate for incorrect answers. Similarity between s and the confederate was manipulated. Ss then punished themselves for wrong answers with electric shock. The s who was moderately similar to his attacker tended to display greater intensities of self-punitive behavior. Greater conflict prior to self-punitive behavior was evident when s and his attacker were highly similar. The instigation to self-aggression is apparently greatest when high similarity is perceived between the self and attacker, but overt aggression is inhibited by as yet unconfirmed factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mobilization of arsenic during one-year incubations of grey aquifer sands from Araihazar, Bangladesh

Elevated As concentrations in shallow groundwater pose a major health threat in Bangladesh and similarly affected countries, yet there is little consensus on the mechanism of As release to groundwater or how it might be influenced by human activities. In this study, the rate of As release was measured directly with incubations lasting 11 months, using sediment and groundwater collected simultaneously in Bangladesh and maintained under anaerobic conditions throughout the study. Groundwater and gray sediment were collected as diluted slurries between 5 and 38 m in depth, a range over which ambient groundwater As concentrations increased from 20 to 100 microg L(-1). Arsenic was released to groundwater in slurries from 5 and 12 m in depth at a relatively constant rate of 21 +/- 4 (2 sigma) and 23 +/- 6 microg As kg(-1) yr(-1), respectively. Amendment with a modest level of acetate increased the rate of As release only at 12 m (82 +/- 18 mirog kg(-1) yr(-1)). Although the groundwater As concentration was initially highest at 38 m depth, no release of As was observed. These results indicate that the spatial distribution of dissolved As in Bangladesh and local rates of release to groundwater are not necessarily linked. Iron release during the incubations did not occur concurrently with As release, providing further confirmation thatthe two processes are not directly coupled. Small periodic additions of oxygen suppressed the release of As from sediments at all three depths, which supports the notion that anoxia is a prerequisite for accumulation of As in Bangladesh groundwater.     

Performance of a household-level arsenic removal system during 4-month deployments in Bangladesh

A simple arsenic removal system was used in Bangladesh by six households for 4 months to treat well water containing 190-750 microg/L As as well as 0.4-20 mg/L Fe and 0.2-1.9 mg/L P. The system removes As from a 16-L batch of water in a bucket by filtration through a sand bed following the addition of about 1.5 g of ferric sulfate and 0.5 g of calcium hypochlorite. Arsenic concentrations in all but 1 of 72 samples of treated water were below the Bangladesh drinking water standard of 50 microg/L for As. Approximately half of the samples also met the World Health Organization (WHO) guideline of 10 microg/L. At the two wells that did not meet the WHO guideline, observations were confirmed by additional experiments in one case ([P] = 1.9 mg/L) but not in the other, suggesting that the latter household was probably not following the instructions. Observed residual As levels are consistent with predictions from a surface complexation model only if the site density is increased to 2 mol/mol of Fe. With the exception of Mn, the average concentrations of other inorganic constituents of health concern (Cr, Ni, Cu, Se, Mo, Cd, Sb, Ba, Hg, Pb, and U) in treated water were below their respective WHO guideline for drinking water.     

Arsenic in tree rings at a highly contaminated site

Arsenic concentrations were measured in annual rings, pith, bark, and leaves of five tree species (four genera) from a site highly contaminated with As in Vineland, New Jersey, and two nearby uncontaminated areas. The highest As concentrations were found in bark (0.68+/-0.89 mg/kg, n=16) and leaves (1.9+/-1.8 mg/kg, n=4) from the contaminated area. Tree-ring As levels from the contaminated area (0.28+/-0.15 mg/kg, n=32) were low but still considerably higher than those from the control areas (0.06+/-0.06 mg/kg, n=30). There is a generally positive relationship between soil and tree-ring As levels. The overall low uptake of As by trees contrasts with that of P, a chemical analog for As(V) in aerated soils. Much higher P concentration in sapwood than in heartwood indicates that P is exported into more recently formed wood during the conversion from sapwood to heartwood; this again is drastically different than the behavior of As which is present in sapwood and heartwood at comparable levels. Variable sapwood As concentrations observed in detailed radial profiles of tree-ring chemistry of a pine and an oak from the contaminated site suggest that As is most likely transported among multiple rings within the sapwood. Therefore, tree species for which sapwood is thin (e.g., oak as in this study) should be preferred for reconstructing the history of contamination of a site. Due to the possibility of lateral translocation between growth rings, further studies are necessary to understand within-tree As transport and storage before dendrochemistry can be confidently accepted for such applications.     

Flushing history as a hydrogeological control on the regional distribution of arsenic in shallow groundwater of the Bengal Basin

Whereas serious health consequences of widespread consumption of groundwater elevated in As have been documented in several South Asian countries, the mechanisms responsible for As mobilization in reducing aquifers remain poorly understood. We document here a previously unrecognized and consistent relationship between dissolved As concentrations in reducing groundwater and the phosphate-mobilizable As content of aquifer sediment for a set of precisely depth-matched samples from across Bangladesh. The relationship holds across nearly 3 orders of magnitude in As concentrations and suggests that regional as well as local patterns of dissolved As in shallow groundwater are set by the solid phase according to a remarkably constant ratio of approximately 250 microg/L dissolved As per 1 mg/kg P-mobilizable As. We use this relationship in a simple model of groundwater recharge to propose that the distribution of groundwater As in shallow aquifers of the Bengal Basin could primarily reflect the different flushing histories of sand formations deposited in the region over the past several thousand years.