Perceived self-other differences in persuasibility: the effects of interpersonal and group-based similarity

Two experiments examined the effects of interpersonal and group-based similarity on perceived self-other differences in persuasibility (i.e. on third-person effects, Davison, 1983). Results of Experiment 1 (N=121), based on experimentally-created groups, indicated that third-person perceptions with respect to the impact of televised product ads were accentuated when the comparison was made with interpersonally different others. Contrary to predictions, third-person perceptions were not affected by group-based similarity (i.e. ingroup or outgroup other). Results of Experiment 2 (N = 102), based an an enduring social identity, indicated that both interpersonal and group-based similarity moderated perceptions of the impact on self and other of least-liked product ads. Overall, third-person effects were more pronounced with respect to interpersonally dissimilar others. However, when social identity was salient, information about interpersonal similarity of the target did not affect perceived self-other differences with respect to ingroup targets. Results also highlighted significant differences in third-person perceptions according to the perceiver's affective evaluation of the persuasive message. (C) 1998 John Wiley & Sons, Ltd.

Gaze angle: a possible mechanism of visual stress in virtual reality headsets

It is known that some Virtual Reality (VR) head-mounted displays (HMDs) can cause temporary deficits in binocular vision. On the other hand, the precise mechanism by which visual stress occurs is unclear. This paper is concerned with a potential source of visual stress that has not been previously considered with regard to VR systems: inappropriate vertical gaze angle. As vertical gaze angle is raised or lowered the 'effort' required of the binocular system also changes. The extent to which changes in vertical gaze angle alter the demands placed upon the vergence eye movement system was explored. The results suggested that visual stress may depend, in part, on vertical gaze angle. The proximity of the display screens within an HMD means that a VR headset should be in the correct vertical location for any individual user. This factor may explain some previous empirical results and has important implications for headset design. Fortuitously, a reasonably simple solution exists.

Pilot-scale extraction of PHB from recombinant E-coli by homogenization and centrifugation

A new method of poly-beta-hydroxybutyrate (PHB) extraction from recombinant E. coli is proposed, using homogenization and centrifugation coupled with sodium hypochlorite treatment. The size of PHB granules and cell debris in homogenates was characterised as a function of the number of homogenization passes. Simulation was used to develop the PHB and cell debris fractionation system, enabling numerical examination of the effects of repeated homogenization and centrifuge-feedrate variation. The simulation provided a good prediction of experimental performance. Sodium hypochlorite treatment was necessary to optimise PHB fractionation. A PHB recovery of 80% at a purity of 96.5% was obtained with the final optimised process. Protein and DNA contained in the resultant product were negligible. The developed process holds promise for significantly reducing the recovery cost associated with PHB manufacture.

Attributions for the performance of self and other: It matters who the "other" is

This study tested hypotheses that locus of causality attributions for the academic performance of others are influenced by whether the other is a specific individual, or a typical other, and whether the other is similar or dissimilar to self. The research was carried out in two studies. Study 1 entailed development of two scales to measure perceptions of interpersonal similarity: 254 Australian undergraduates rated their similarity to either a specific other or to typical other students. In Study 2, 332 subjects completed one of the 16-item scales developed in Study 1, along with Rosenberg's self-esteem scale, and self-attribution and other-attribution versions of the Multidimensional Multi-attribution Causation Scale (MMCS). Results showed that attributions for the academic performance of others were strongly affected by whether the other was perceived to be similar or dissimilar to self, especially when the other was a specific individual. In particular, causal attributions for similar specific others were more favourable than attributions for self.

An experimental study of the effects of work stress, work control, and task information on adjustment

The present study was designed to examine the main and interactive effects of task demands, work control, and task information on levels of adjustment. Task demands, work control, and task information were manipulated in an experimental setting where participants completed a letter-sorting activity (N = 128). Indicators of adjustment included measures of positive mood, participants' perceptions of task performance, and task satisfaction. Results of the present study provided some support for the main effects of objective task demands, work control, and task information on levels of adjustment. At the subjective level of analysis, there was some evidence to suggest that work control and task information interacted in their effects on levels of adjustment. There was minimal support for the proposal that work control and task information would buffer the negative effects of task demands on adjustment. There was, however, some evidence to suggest that the stress-buffering role of subjective work control was more marked at high, rather than low, levels of subjective task information.

Analysis of pore-fluid pressure gradient and effective vertical-stress gradient distribution in layered hydrodynamic systems

A theoretical analysis is carried out to investigate the pore-fluid pressure gradient and effective vertical-stress gradient distribution in fluid saturated porous rock masses in layered hydrodynamic systems. Three important concepts, namely the critical porosity of a porous medium, the intrinsic Fore-fluid pressure and the intrinsic effective vertical stress of the solid matrix, are presented and discussed. Using some basic scientific principles, we derive analytical solutions and explore the conditions under which either the intrinsic pore-fluid pressure gradient or the intrinsic effective vertical-stress gradient can be maintained at the value of the lithostatic pressure gradient. Even though the intrinsic pore-fluid pressure gradient can be maintained at the value of the lithostatic pressure gradient in a single layer, it is impossible to maintain it at this value in all layers in a layered hydrodynamic system, unless all layers have the same permeability and porosity simultaneously. However, the intrinsic effective vertical-stress gradient of the solid matrix can be maintained at a value close to the lithostatic pressure gradient in all layers in any layered hydrodynamic system within the scope of this study.

Sources of information about HIV/AIDS and perceived risk of infection among heterosexual young adults: 1989 and 1994

This paper reports a study of sources of information about HIV/AIDS and trust of the sources among heterosexuals in 1989 (113 females and 91 males) and 1994 (185 females and 66 males). We also examined whether perceived personal risk of HIV infection was predicted by sources of information about HIV/AIDS, trust of the sources, how informed about AIDS people believed they were, and perceived risk of infection to others, as well as whether there was a relationship between perceived personal risk and safe sex behaviour Participants received most of their information about AIDS/HIV from magazines, newspapers, and television, but placed most trust on sources such as doctors and HIV/AIDS organisations. Perceived personal risk was influenced most by perceived risk to friends and to people with the same sexual practices. In the 1994 sample, perceived personal risk was correlated with the amount of condom use among participants with sexual experience. These results indicate ther has been. relative stability across a five-year period. They also point to the continuing discrepancy among young heterosexuals between the most-used and most-trusted sources of information, as well as to the importance of peer influence on perceptions of personal risk of HIV infection.

Outbreaks of pink wax scale, Ceroplastes rubens Maskell (Hemiptera : Coccidae), on umbrella trees in south-eastern Queensland: Patterns of parasitisation

The degree and distribution of parasitisation in relation to densities of pink wax scale, Ceroplastes rubens Maskell, on umbrella trees, Schefflera actinophylla (Endl.), in south-eastern Queensland were investigated to determine whether scale outbreaks could be attributed, in part, to low levels of parasitisation. Rates of parasitisation were independent of or inversely dependent on host density, and highly variable, especially at low densities. The absence of density dependent parasitisation may occur as a result of: (i) non-aggregation by parasitoids; (ii) aggregation by parasitoids where parasitisation is limited by intrinsic or extrinsic factors; and/or (iii) high rates of hyperparasitisation.

Insufficiently active Australian college students: Perceived personal, social, and environmental influences

Background. A sustainable pattern of participation in physical activity is important in the maintenance of health and prevention of disease, College students are in transition from an active youth to a more sedentary adult behavior pattern. Methods. We assessed self-reported physical activity and other characteristics in a sample of 2,729 male and female students (median age was 20 years) recruited from representative courses and year levels at four Australian College campuses. They were categorized as sufficiently or insufficiently active, using estimates of energy expenditure (kcal/week) derived from self-reported physical activity, Personal factors (self-efficacy, job status, enjoyment), social factors (social support from family/friends), and environmental factors (awareness of facilities, gym membership) were also assessed. Results. Forty-seven percent of females and 32% of males were insufficiently active. For females, the significant independent predictors of being insufficiently active were lower social support from family and friends, lower enjoyment of activity, and not working. For males, predictors were lower social support from family and friends, lower enjoyment of activity, and being older. Conclusions. Factors associated with physical activity participation (particularly social support from family and friends) can inform physical activity strategies directed at young adults in the college setting. (C) 1999 American Health Foundation and Academic Press.

Modeling the fluid-flow-induced stress and collapse in a dendritic network

An analytical approach to the stress development in the coherent dendritic network during solidification is proposed. Under the assumption that stresses are developed in the network as a result of the friction resisting shrinkage-induced interdendritic fluid flow, the model predicts the stresses in the solid. The calculations reflect the expected effects of postponed dendrite coherency, slower solidification conditions, and variations of eutectic volume fraction and shrinkage. Comparing the calculated stresses to the measured shear strength of equiaxed mushy zones shows that it is possible for the stresses to exceed the strength, thereby resulting in reorientation or collapse of the dendritic network.

The moderating role of task characteristics in determining responses to a stressful work simulation

Two experimental studies were conducted to examine whether the stress-buffering effects of behavioral control on work task responses varied as a function of procedural information. Study 1 manipulated low and high levels of task demands, behavioral control, and procedural information for 128 introductory psychology students completing an in-basket activity. ANOVA procedures revealed a significant three-way interaction among these variables in the prediction of subjective task performance and task satisfaction. It was found that procedural information buffered the negative effects of task demands on ratings of performance and satisfaction only under conditions of low behavioral control. This pattern of results suggests that procedural information may have a compensatory effect when the work environment is characterized by a combination of high task demands and low behavioral control. Study 2 (N = 256) utilized simple and complex versions of the in-basket activity to examine the extent to which the interactive relationship among task demands, behavioral control, and procedural information varied as a function of task complexity. There was further support for the stress-buffering role of procedural information on work task responses under conditions of low behavioral control. This effect was, however, only present when the in-basket activity was characterized by high task complexity, suggesting that the interactive relationship among these variables may depend on the type of tasks performed at work. Copyright (C) 1999 John Wiley & Sons, Ltd.

Parental reactions to infant death: The effects of resources and coping strategies

The aim of this research was to examine, from a stress and coping perspective, the effects of resources (both personal and environmental) and coping strategies on parental reactions to infant death. One hundred and twenty-seven parents (60 fathers, 67 mothers) participated in the study. The predictors of parental distress (background factors, resources, coping methods) were initially assessed at 4-6 weeks post-loss. Parental distress (assessed using a composite measure of psychiatric disturbance, physical symptoms, and perinatal grief) was further assessed at 6 months post-loss and at 15 months postloss. After control for the stability in adjustment across time, there was consistent evidence that higher levels of education were associated with lower levels of parental distress over time. Among mothers, the number of friends in whom mothers had the confidence to confide emerged as a positive predictor of adjustment to infant death. A reliance on problem-focused coping was associated with greater maternal distress at 6 months post-loss, whereas coping by seeking support was associated with less distress at 15 months post-loss. There is no evidence that background factors and resources influenced parental distress through coping.

Climate change, coral bleaching and the future of the world's coral reefs

Sea temperatures in many tropical regions have increased by almost 1 degrees C over the past 100 years, and are currently increasing at similar to 1-2 degrees C per century. Coral bleaching occurs when the thermal tolerance of corals and their photosynthetic symbionts (zooxanthellae) is exceeded. Mass coral bleaching has occurred in association with episodes of elevated sea temperatures over the past 20 years and involves the loss of the zooxanthellae following chronic photoinhibition. Mass bleaching has resulted in significant losses of live coral in many parts of the world. This paper considers the biochemical, physiological and ecological perspectives of coral bleaching. It also uses the outputs of four runs from three models of global climate change which simulate changes in sea temperature and hence how the frequency and intensity of bleaching events will change over the next 100 years. The results suggest that the thermal tolerances of reef-building corals are likely to be exceeded every year within the next few decades. Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years. Most information suggests that the capacity for acclimation by corals has already been exceeded, and that adaptation will be too slow to avert a decline in the quality of the world's reefs. The rapidity of the changes that are predicted indicates a major problem for tropical marine ecosystems and suggests that unrestrained warming cannot occur without the loss and degradation of coral reefs on a global scale.

PAM chlorophyll fluorometry: a new in situ technique for stress assessment in scleractinian corals, used to examine the effects of cyanide from cyanide fishing

Sodium cyanide is being used on reefs in the Asia-Pacific region to capture live fish for the aquarium industry, and to supply a rapidly growing, restaurant-based demand, The effects of cyanide on reef biota have not been fully explored. To investigate its effect on hard corals, we exposed small branch lips of Stylophora pistillata and Acropora aspera to cyanide concentrations estimated to occur during cyanide fishing. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques were used to examine photoinhibition and photosynthetic electron transport in the symbiotic algae (zooxanthellae) in the tissues of the corals, These measurements were made in situ and in real time using a recently developed submersible PAM fluorometer. In S. pistillata. exposure to cyanide resulted in an almost complete cessation in photosynthetic electron transport rate. Both species displayed marked decreases in the ratio of variable fluorescence (F-v) to maximal fluorescence (F-m) (dark-adapted F-v/F-m), following exposure to cyanide, signifying a decrease in photochemical efficiency. Dark-adapted F-v/F-m recovered to normal levels in similar to 6 d, although intense tissue discolouration, a phenomenon well-recognised as coral 'bleaching' was observed during this period, Bleaching was caused by loss of zooxanthellae from the coral tissues, a well-recognised sub-lethal stress response of corals. Using the technique of chlorophyll fluorescence quenching analysis, corals exposed to cyanide did not show light activation of Calvin cycle enzymes and developed high levels of non-photochemical quenching (q(N)), signifying the photoprotective dissipation of excess light as heat, These features are symptomatic of the known properties of cyanide as an inhibitor of enzymes of the Calvin cycle. The results of this in situ study show that an impairment of zooxanthellar photosynthesis is; the site of cyanide-mediated toxicity, and is the cue that causes corals to release their symbiotic zooxanthellac following cyanide exposure. This study demonstrates the efficacy of PBM fluorometry as a new tool for in situ stress assessment in zooxanthellate scleractinian corals. (C) 1999 Elsevier Science Ltd. All rights reserved.