Water Activity and Temperature Effects on Fungal Growth and Ochratoxin A Production by Ochratoxigenic Aspergillus carbonarius Isolated from Tunisian Grapes

ABSTRACT: This study investigated the effects of temperature (15 to 37 °C) and water activity (0.90 to 0.99) on the growth and production of ochratoxin A (OTA) by Aspergillus carbonarius cultured on synthetic nutrient medium (SNM) after 5 and 10 d of incubation. Total of 8 ochratoxigenic A. carbonarius, isolated from vineyards located in different regions of Tunisia, were used. Growth data were modeled by the flexible model of Baranyi and growth rates at each set of conditions were obtained. For both growth and OTA production, optimal water activity was 0.99; however, optimal temperature varied. The optimal temperature for growth was 30 °C. At 37 °C, the growth rate decreased significantly (P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 °C with the optimum one depending on the isolate tested. Significant amounts of OTA were produced after only 5 d of incubation. Our results showed that A. carbonarius isolated from Tunisian grapes behave as those from European and Australian grapes, as reported in the literature, although some differences in trends for growth and OTA production were observed.     

Elastic properties of porous oxide ceramics prepared using starch as a pore-forming agent

The elastic properties, in particular the tensile modulus (Young's modulus) and Poisson ratio, of porous alumina, zirconia, and alumina–zirconia composite ceramics are studied using the resonance frequency method and the results compared with theoretical predictions. Starch is used as a pore-forming agent, so that the resulting microstructure is essentially of the matrix-inclusion type (with large bulk pores, connected by small throats when a percolation threshold is exceeded). It is found that for this type of microstructure the porosity dependence of the Young's modulus is significantly below the upper Hashin–Shtrikman bound and the power-law prediction; it corresponds well, however, to a recently proposed exponential relation and to an empirical volume-weighted average of the upper and lower Hashin–Shtrikman bounds. Results for all three types of ceramics indicate that – in the porosity range considered, i.e. up to approximately 50% – the Poisson ratio depends only slightly on porosity.     

Effects of coxsackievirus B3 infection on the acute-phase protein metallothionein and on cytochrome P-4501A1 involved in the detoxification processes of TCDD in the mouse

During acute infections, the synthesis of acute-phase proteins and other proteins participating in the host defence are stimulated in the liver and kidney. In previous studies of coxsackievirus B3 (CB3) infection in mice, we found that cadmium (Cd) accumulates in the kidney, whereas 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) accumulates in the liver. To study if CB3 infection affects the synthesis of the Cd-binding protein metallothionein (MT) and the TCDD-binding/detoxifying cytochrome P-450 (CYP-450) isozyme CYP1A1, the basal and TCDD-induced levels of serum MT and liver CYP1A1 isozyme were determined in healthy and CB3-infected A/J mice. Furthermore, because interferons affect CYP450 activity, the serum levels of the interferons alpha (IFN-alpha) and -beta (IFN-beta) were measured in CB3-infected mice and in mice treated with the interferon-inducer polyinosinic/polycytidylic acid (poly I/C). Virus or poly I/C was administered intraperitoneally (i.p.) on day 0 and 500 ng TCDD/kg bodyweight on day 1. On day 4, CB3 infection had induced MT approximately 10-fold, regardless of TCDD treatment (P < 0.01 in infected mice and P < 0.001 in infected, TCDD-treated mice). TCDD alone induced a 10-fold increase in CYP1A1 activity (P < 0.001), whereas infection alone suppressed the normal CYP1A1 activity by 75% (P < 0.001). Infection also suppressed the TCDD-induced CYP1A1 activity by approximately 30% (n.s.). Poly I/C suppressed CYP1A1 by 20-25% (n.s.) at both basal and TCDD-induced levels. Serum IFN-alpha and IFN-beta levels were undetectable in controls, in TCDD-treated and in the poly I/C-treated groups on day 4, probably because the short IFN peak is detectable only hours after injection. Conversely, on day 4 of the infection, IFN-alpha and IFN-beta were consistently raised in the TCDD-treated infected mice, whereas increased IFNs as a result of infection alone could be detected in only one individual. These results suggest that the normal host responses during acute infections down-regulate detoxifying processes in favour of acute-phase protein synthesis. This may explain the observed changed pattern of accumulation, excretion and toxicity of the environmental pollutants cadmium and TCDD during this common virus infection.     

The SARS Crisis: Was Anybody Responsible?

As scholars in fields such as media studies, crisis studies and public policy studies have argued, there exists a fundamental link between crises and the media. Once an event has been interpreted as a crisis, questions of accountability inevitably appear on the media agenda, and the struggle to attribute blame and responsibility to a specific entity or entities—the blame game—thus becomes an inexorable part of the crisis process. Focusing on three liberal Western newspapers with an international, primarily Western elite readership and a reputation for in‐depth analysis of global events, The Economist, the Financial Times and the International Herald Tribune, this article employs Iyengar's and Valkenburg's notions of responsibility frames to examine whether initial coverage of the 2003 SARS crisis in these accounts held any particular entity accountable for the crisis, looks at three key themes used to communicate to the reader a particular way of thinking about responsibility for SARS and examines some of the consequences of the kind of responsibility frame constructed around the SARS crisis in these accounts. As our findings show, there is an entity that the early news accounts studied consistently held responsible for the 2003 SARS crisis, the Chinese system, and the corresponding responsibility frame at operation in these accounts is thematic rather than episodic in nature, since it consistently places the SARS crisis within a broader context (a product of “China” itself and/or of societal‐governmental forces in China) rather than in relation to a specific episode or as the result of the particular actions of individuals. The SARS crisis narrative therefore presented in these accounts tells the story of an anachronistic Chinese system faced with a contemporary health threat that, by its very nature, it is incapable of assessing accurately or managing responsibly. By way of conclusion, we argue that, while the use of such a thematic frame to explain China's role in the 2003 SARS crisis may be accurate in certain respects, this frame falls short in other respects and proves particularly inadequate to the challenge of capturing the economic complexities of China's role during the crisis.     

Effects of mothers' perceptions of children's competence: The moderating role of mothers' theories of competence.

There is much evidence that parents' perceptions of children's competence affect the development of children's academic functioning. In the current research, the possibility that this is moderated by parents' theories about the stability of competence was examined. In a 2-wave, 1-year study of 126 children (9 to 12 years old) and their mothers, children's academic functioning (i.e., grades, perceptions of competence, attributions for performance, and mastery orientation) and affective functioning (i.e., self-esteem and depressive symptoms) were examined. Among mothers with relatively high entity theories, their perceptions acted as self-fulfilling prophecies foreshadowing children's academic and affective functioning over time. However, among mothers with relatively low entity theories, mothers' perceptions did not predict children's academic and affective functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Letter position information and printed word perception: The relative-position priming constraint.

Six experiments apply the masked priming paradigm to investigate how letter position information is computed during printed word perception. Primes formed by a subset of the target's letters facilitated target recognition as long as the relative position of letters was respected across prime and target (e.g., "arict" vs. "acirt" as primes for the target "apricot"). Priming effects were not influenced by whether or not absolute, length-dependent position was respected (e.g., "a-ric-t" vs. "arict"/"ar-i-ct"). Position of overlap of relative-position primes (e.g., apric-apricot; ricot-apricot; arict-apricot) was found to have little influence on the size of priming effects, particularly in conditions (i.e., 33 ms prime durations) where there was no evidence for phonological priming. The results constrain possible schemes for letter position coding. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Some approaches to improve tree-based nearest neighbour search algorithms

Nearest neighbour search is a widely used technique in pattern recognition. During the last three decades a large number of fast algorithms have been proposed. In this work we are interested in algorithms that can be used with any dissimilarity function provided that it fits the mathematical notion of distance.Some of such algorithms organize, in preprocessing time, the data in a tree structure that is traversed in search time to find the nearest neighbour. The speedup is obtained using some pruning rules that avoid the traversal of some parts of the tree.In this work two new decomposition methods to build the tree and three new pruning rules are explored. The behaviour of our proposal is studied through experiments with synthetic and real data.