15 research outputs found

    Effect of temperature, rainfall and planting date on aflatoxin and fumonisin contamination in commercial Bt and non-Bt corn hybrids in Arkansas

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    Corn (maize, Zea mays) is susceptible to contamination with aflatoxins, fumonisins and other mycotoxins, particularly in the southeastern USA. In principle, mycotoxin contamination could be reduced in commercial corn hybrids with shorter growing seasons by planting at dates which minimize plant stress during the critical kernel-filling period. To evaluate this strategy, commercial Bt and non-Bt hybrids were planted in Arkansas in mid-April and early May of 2002, 2004 and 2005. The mid-April planting date resulted in lower aflatoxin contamination in harvested corn each yr and in significantly less frequent contamination above a regulatory action level in 2005 and overall than did the early-May planting date in both Bt and non-Bt corn. The mid-April planting date resulted in significantly lower total fumonisin contamination in harvested corn and in less frequent contamination above a regulatory advisory level than the early May planting date in 2 of 3 yr and overall in both Bt and non-Bt corn. All fumonisin subtypes studied were reduced. Frequent co-occurrence of aflatoxin and fumonisin was observed. Fumonisin levels averaged lower in Bt hybrids than in non-Bt hybrids at all plantings. Reduced aflatoxin and fumonisin contamination with mid-April planting could not be explained by any measure of heat stress during the kernel-filling period.Le maĂŻs (Zea mays) est sensible Ă  la contamination par les aflatoxines, les fumonisines et d'autres mycotoxines, surtout dans le sud-est des États-Unis. En principe, la contamination par les mycotoxines pourrait ĂȘtre diminuĂ©e chez les hybrides commerciaux de maĂŻs par des saisons de croissance plus courtes en plantant Ă  des dates qui minimisent le stress sur les plantes au moment de la pĂ©riode critique du remplissage des grains. Pour Ă©valuer cette stratĂ©gie, des hybrides commerciaux Bt et non Bt ont Ă©tĂ© semĂ©s en Arkansas de la mi-avril au dĂ©but de mai 2002, 2004 et 2005. Pour toutes les annĂ©es, tant pour le maĂŻs Bt que le non Bt, le grain issu des semis de la mi-avril Ă©tait moins contaminĂ© aux aflatoxines que celui semĂ© au dĂ©but de mai. De mĂȘme, la contamination supĂ©rieure aux niveaux lĂ©galement acceptĂ©s a Ă©tĂ© moindre en 2005 et dans l'ensemble pour les semis de la mi-avril. Avec les semis de la mi-avril, il y avait significativement moins de contamination par les fumonisines dans le grain rĂ©coltĂ© et moins de contamination supĂ©rieure aux niveaux lĂ©galement acceptĂ©s qu'avec les semis du dĂ©but de mai pour deux des trois annĂ©es et dans l'ensemble, tant pour le maĂŻs Bt que celui non Bt. La quantitĂ© de tous les sous-types de fumonisines Ă©tudiĂ©s a Ă©tĂ© diminuĂ©e. La prĂ©sence simultanĂ©e d'aflatoxines et de fumonisines a frĂ©quemment Ă©tĂ© observĂ©e. Pour tous les semis, les quantitĂ©s de fumonisines des hybrides Bt ont Ă©tĂ© infĂ©rieures en moyenne Ă  celles des hybrides non Bt. Les moindres contaminations par les aflatoxines et les fumonisines avec les semis de la mi-avril n'ont pu ĂȘtre expliquĂ©es par aucune des mesures du stress causĂ© par la chaleur lors de la pĂ©riode du remplissage des grains

    Search for the standard model Higgs boson at LEP

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    Towards effective ecological restoration: Investigating knowledge co‐production on fish–habitat relationships with Aquatic Habitat Toronto

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    Abstract For decades, the working paradigm for ecological restoration was independent operation of knowledge generators (researchers and scientists) and knowledge users (decision makers and practitioners), resulting in a knowledge–action gap. Knowledge co‐production is a collaborative process where research is conducted in a respectful and engaging manner with continuous knowledge exchange and heralded as a means of bridging the divide. Aquatic Habitat Toronto (AHT) is a unique consensus‐based partnership with diverse member agencies that engage in restoration ecology and practice along the Toronto Waterfront of Lake Ontario, Canada. Here, we examine the process that AHT uses to enable knowledge co‐production and identify associated benefits and challenges. Benefits to AHT's consensus‐based partnership include advanced notice of projects, access to diverse expertise and local knowledge, increased understanding of fish habitat, adoption of novel restoration techniques and more effective restoration and improved knowledge exchange, collectively mitigating the knowledge–action divide. Challenges of knowledge co‐production facilitated by AHT include consistent agency participation and meaningful engagement, closed or exclusive networks, time commitments and limited financial resources, evolving political landscapes, stability of funding cycles and issues stemming from varying goals and relevancy. Key recommendations for ensuring that knowledge co‐production results in actionable science and for maximizing the effectiveness of ecological restoration using AHT's format include securing long‐term and stable funding, developing relationships across agencies and allied partners, engaging early, outlining goals/objectives collaboratively, conducting before and after scientific monitoring, minimizing personal biases, periodically reviewing partnerships to maximize inclusivity, sharing successes (and failures) broadly, and providing open data. AHT embraces an approach that includes integrated planning with multi‐jurisdictional support with diverse partners at a tractable scale and we argue that this should be the standard model of aquatic ecosystem management

    Emotions and actions associated with norm-breaking events.

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    Norms have a strong influence on human social interactions, but the emotions and actions associated with norm-breaking events have not been systematically studied. We asked subjects to imagine themselves in a conflict situation and then to report how they would feel, how they would act, and how they would imagine the feelings and actions of their opponent. By altering the fictional scenario that they were asked to imagine (weak vs. strong norm) and the perspective of the subject (norm-breaker vs. the one whose norm has been violated), the emotions and actions associated with norm-breaking events could be examined. We tested the following hypotheses: (1) norms create emotional asymmetries that resolve conflicts in otherwise symmetrical contest situations; (2) sex differences exist in response to norm-breaking events, with males more prone to violence than females; (3) individual differences exist in response to norm-breaking events, along the lines predicted by theoretical models; and (4) emotions and actions attributed to one's opponent are distorted in ways that can be interpreted as adaptive for the believer. In addition to these basic hypotheses, we address more subtle issues concerning the particular emotions provoked by norm-breaking events, the degree to which emotional response is fine-tuned to the situation, and the degree to which emotional response correlates with anticipated behavioral response. We discuss the relevance of our study to the general study of emotions and the use of fictional scenarios as a research method in addition to the study of norms from an evolutionary perspective

    Search for the standard model Higgs boson at LEP

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    The four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb(-1) of e(+)e(-) collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The corresponding confidences have been computed as functions of the hypothetical Higgs boson mass. A lower bound of 114.4 GeV/c(2) is established, at the 95% confidence level, on the mass of the Standard Model Higgs boson. The LEP data are also used to set upper bounds on the HZZ coupling for various assumptions concerning the decay of the Higgs boson. (C) 2003 Elsevier B.V. All rights reserved

    Precision Electroweak Measurements on the Z resonance.

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    We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron–positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward–backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: The number of light neutrino species is determined to be 2.9840±0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward–backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, , and the mass of the W boson, . These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than at 95% confidence level
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