Dreissenid mussels from the Great Lakes contain elevated thiaminase activity

We examined thiaminase activity in dreissenid mussels collected at different depths and seasons, and from various locations in Lakes Michigan, Ontario, and Huron. Here we present evidence that two dreissenid mussel species (Dreissena bugensis and D. polymorpha) contain thiaminase activity that is 5–100 fold greater than observed in Great Lakes fishes. Thiaminase activity in zebra mussels ranged from 10,600 to 47,900 pmol g^− 1·min^− 1 and activities in quagga mussels ranged from 19,500 to 223,800 pmol g^− 1·min^− 1. Activity in the mussels was greatest in spring, less in summer, and least in fall. Additionally, we observed greater thiaminase activity in dreissenid mussels collected at shallow depths compared to mussels collected at deeper depths. Dreissenids constitute a significant and previously unknown pool of thiaminase in the Great Lakes food web compared to other known sources of this thiamine (vitamin B₁)-degrading enzyme. Thiaminase in forage fish of the Great Lakes has been causally linked to thiamine deficiency in salmonines. We currently do not know whether linkages exist between thiaminase activities observed in dreissenids and the thiaminase activities in higher trophic levels of the Great Lakes food web. However, the extreme thiaminase activities observed in dreissenids from the Great Lakes may represent a serious unanticipated negative effect of these exotic species on Great Lakes ecosystems.     

High hydrostatic pressure treatment of finfish to inactivate Anisakis simplex

High hydrostatic pressure has been demonstrated to be a useful technique for treating food to reduce the number of pathogenic organisms and to extend shelf life. Most research in this area has focused on bacteria. However, a concern in the sashimi (raw fish) industry is that nematode worms such as Anisakis simplex occur naturally in cold-water marine fish. The objectives of this research were to perform a pilot study to determine the effect of high hydrostatic pressure on the viability of Anisakis simplex larvae, commonly found in king salmon and arrowtooth flounder, and to evaluate the effects of high hydrostatic pressure on the color and texture of the fish fillets. Pieces of fish (ca. 100 g per bag) containing 13 to 118 larvae were exposed to pressures of up to 80,000 lb/in2 (552 MPa) for up to 180 s. The times and pressures required to kill 100% of the larvae were as follows: 30 to 60 s at 60,000 lb/in2 (414 MPa), 90 to 180 s at 40,000 lb/in2 (276 MPa), and 180 s at 30,000 lb/in2 (207 MPa). For all salmon treatments that killed 100% of the larvae, a significant increase in the whiteness of the flesh was observed. Although high hydrostatic pressure was effective in killing A. simplex larvae in raw fish fillets, its significant effect on the color and overall appearance of the fillet may limit its application to the processing of fish for raw-fish markets.     

Does willingness to pay for green energy differ by source?

We present the findings of a choice experiment designed to estimate consumer preferences and willingness-to-pay (WTP) for voluntary participation in green energy electricity programs. Our model estimates WTP for a generic “green energy” source and compares it to WTP for green energy from specific sources, including wind, solar, farm methane, and biomass. Our results show that there exists a positive WTP for green energy electricity. Further, individuals have a preference for solar over a generic green and wind. Biomass and farm methane are found to be the least preferred sources.     

The natural history and fisheries ecology of Lake Chilwa,southern Malawi

Lake Chilwa produces between zero and 24,000 metric tons of fish per year, making it one of the most productive but variable lakes in Africa. The size of the lake varies seasonally and among years, sometimes drying completely. Its surrounding wetland and floodplain provide habitat for a diversity of birds and economically valuable grasses and reeds. When the lake has water, there is considerable activity on its shores and temporary fishing villages spring up. People move in and out of the lake basin in concert with these seasonal and longer term changes. This paper examines the environmental dynamics of Lake Chilwa and its surrounding wetlands, presents an overview of the socio-economic context of the area and discusses threats to this resilient system that might occur as a result of climate change. We conclude that management of Lake Chilwa must place the lake in the wider economic and ecological system in which it is situated. Ultimately, land-use practices within the basin present more of a threat to the resilience of the fishery and people's livelihoods than overfishing or a strict focus on the lake's resources. These perspectives present significant challenges to conventional fisheries governance.     

Faking and personality assessment in personnel selection: Advancing models of faking.

Personality testing is a particularly valuable preemployment assessment tool when one matches personality traits to job requirements. The authors explain that, unlike most other common personnel selection methods, the unique value of personality assessment in personnel selection stems from its tendency to predict the choice to perform, or “will-do” aspects of job performance. The effect of faking on the value of personality testing is discussed, and the authors suggest that personality testing’s contribution to personnel selection could be leveraged if more were known about the psychological process underlying applicant faking behaviour. To this end, the authors present an improved general model of the applicant faking process as well as a new “faking decision tree.” (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A stress-coping profile of opioid dependent individuals entering naltrexone treatment: A comparison with healthy controls.

Background: Stress is known to increase addiction vulnerability and risk of relapse to substance use. Purpose & Method: We compared opioid dependent individuals entering naltrexone treatment (n = 57) with healthy controls (n = 75) on measures of stress, coping, and social support and examined the relative contribution of group membership, coping, and social support to stress within the sample. Analyses of variance (ANOVA) and covariance (ANCOVA), and stepwise multiple regression were conducted. Results: Compared with controls, opioid dependent subjects reported greater stress, less use of adaptive coping, but comparable use of maladaptive/avoidant coping. No group differences were found with respect to social support. Perceived stress was predicted by group membership, low social support, and greater use of maladaptive/avoidant coping, and the prediction by social support and maladaptive/avoidant coping did not differ by group. Conclusion: Opioid dependent individuals entering naltrexone treatment experience higher levels of stress and report less use of adaptive coping strategies when compared with controls. Group membership, maladaptive/avoidant coping, and social support independently contribute to perceived stress. Findings suggest that novel treatment approaches that decrease maladaptive/avoidant coping and improve social support are important aspects of decreasing stress during early recovery from opioid addiction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In situ observation of tensile deformation of high-pressure die-cast specimens of AM50 alloy

In situ observation of HPDC AM50 alloy in the SEM chamber was performed to study the changes of the micro-voids and the β phase during tensile deformation. The results suggested that micro-voids had little change in the elastic region, opened linearly with increasing load in the plastic region and led to final fracture. The detachment of β phase from the interface was also observed in the plastic region and there was no evidence to suggest that the detachment led to the final fracture.     

Interpretation of evoked potentials: A neurophysiological perspective.

Discusses 3 aspects of the problem of inferring information about nervous system function from evoked potential (EP) measurements: (1) electrogenesis of EPs, including their relation to the geometry of individual cells and cell groups; (2) effects of recording EPs from the scalp or body surface instead of directly from neural tissue; and (3) quantitative approaches to the problem of EP source localization. Primary emphasis is placed on the intimate relationship between EPs, anatomical structures, and physiological processes that give rise to them, and the properties of potential fields in conductive media. (French abstract) (86 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpretation of the preswitching behaviour of chalcogenide-glass switches in terms of a space-charge-injection mechanism

Many of the characteristics of threshold switching devices may be explained in terms of a simple space-charge-injection model if it is assumed that switching occurs at a critical electric-field strength. Experimental evidence to support this hypothesis is described.     

The Dramatic Impact of Silicon Technology

Approximately twelve years ago the first double-diffused silicon transistor was offered to the marketplace. These first transistors sold for $70.00. Today it is possible to purchase an integrated memory circuit with several thousand transistors plus several thousand resistors and diodes for less the original selling price of this first transistor.