Biochemistry and genetics of insecticide resistance in the Colorado potato beetle.

The purpose of this dissertation was to determine the biochemical mechanisms of azinphosmethyl, permethrin, and abamectin resistance in the Colorado potato beetle (Leptinotarsa decemlineata (Say)) in the hope that this information may be used to construct resistance management strategies. Chromogenic substrates, as well as the in vivo and in vitro metabolism of the three radiolabelled insecticides, were used to determine the metabolic and pharmocokinetic differences of the strains. Azinphosmethyl resistance was due to reduced penetration of azinphosmethyl, increased monooxygenase activity towards azinphosmethyl, and an altered acetylcholinesterase. Monooxygenase activity appears to be the most important mechanism in azinphosmethyl-resistance, but reduced penetration and altered acetylcholinesterase probably have significant roles in the high level of azinphosmethyl-resistance in CPB. Permethrin-resistance appears to be due to increased carboxylesterase activity and site-insensitivity. An increased level of carboxylesterase activity was apparent from a higher V\sb{max} towards carboxylesterase substrates and increased hydrolytic metabolites of permethrin. This carboxylesterase is membrane-associated. An isogenic permethrin-resistant strain was determined to be cross-resistant to DDT, indicating site-insensitivity was another mechanism involved in permethrin-resistance. Abamectin-resistance in two strains was determined to be polygenic. Both strains exhibited high levels of synergism to PBO and moderate levels to DEF. Both strains had elevated levels of cytochrome P450 and oxidative abamectin metabolites in vivo and in vitro. This is the probable reason for the higher levels of excreted compound in the abamectin-resistant strains. Carboxylesterase activity was greatly increased in the abamectin-resistant strains. Carboxylesterases may hydrolyze or sequester abamectin in the resistant strains

FLOSSSim: Understanding the Free/Libre Open Source Software (FLOSS) Development Process through Agent-Based Modeling

abstract: Free/Libre Open Source Software (FLOSS) is the product of volunteers collaborating to build software in an open, public manner. The large number of FLOSS projects, combined with the data that is inherently archived with this online process, make studying this phenomenon attractive. Some FLOSS projects are very functional, well-known, and successful, such as Linux, the Apache Web Server, and Firefox. However, for every successful FLOSS project there are 100's of projects that are unsuccessful. These projects fail to attract sufficient interest from developers and users and become inactive or abandoned before useful functionality is achieved. The goal of this research is to better understand the open source development process and gain insight into why some FLOSS projects succeed while others fail. This dissertation presents an agent-based model of the FLOSS development process. The model is built around the concept that projects must manage to attract contributions from a limited pool of participants in order to progress. In the model developer and user agents select from a landscape of competing FLOSS projects based on perceived utility. Via the selections that are made and subsequent contributions, some projects are propelled to success while others remain stagnant and inactive. Findings from a diverse set of empirical studies of FLOSS projects are used to formulate the model, which is then calibrated on empirical data from multiple sources of public FLOSS data. The model is able to reproduce key characteristics observed in the FLOSS domain and is capable of making accurate predictions. The model is used to gain a better understanding of the FLOSS development process, including what it means for FLOSS projects to be successful and what conditions increase the probability of project success. It is shown that FLOSS is a producer-driven process, and project factors that are important for developers selecting projects are identified. In addition, it is shown that projects are sensitive to when core developers make contributions, and the exhibited bandwagon effects mean that some projects will be successful regardless of competing projects. Recommendations for improving software engineering in general based on the positive characteristics of FLOSS are also presented.Dissertation/ThesisPh.D. Computer Science 201

A detailed study of the diastereoselective catalytic hydrogenation of 6-hydroxytetrahydroisoquinoline-(3R)-carboxylic ester intermediates

A key step towards a highly-selective antagonist of ionotropic glutamate receptors entails the diastereoselective arene hydrogenation of an enantiopure tetrahydroisoquinoline. An extensive screen using parallel reactors was conducted and led to the discovery of several Pd/C catalysts giving high yield and improved diastereoselectivity from 75 : 25 to 95 : 5. A detailed kinetic study of the best system was performed and supports the reduction occuring in two-steps.

Characterization of the Plasmidic or Chromosomal cpe Gene and Metabolic Activities in Clostridium perfringens Isolates from Food in San Luis - Argentina

Food poisoning and non-food poisoning illnesses due to C. perfringens (by enterotoxin production) have been associated to chromosomal or plasmidic location of the cpe gene, respectively. Clostridial pathogenicity has been correlated to protease and azoreductase production.The aim of this work was: i) to assess the sanitary-hygienic quality of dehydrated soups (100 samples) consumed in San Luis – Argentina; ii) to verify the presence of C. perfringens in these food products using the "Most Probable Number" method (MPN) and plate-counting methods; iii) to characterise enterotoxigenicity in strain isolates by RPLA; iv) to determine the chromosomal or plasmidic location of the cpe gene in enterotoxigenic strains previously isolated from food in our lab, using PCR; v) to correlate chromosomal cpe and spore heat-resistance; vi) to compare protease activity in cpe+ and cpe– strains; and vii) to compare azoreductase activity in cpe+ and cpe– strains. Twenty-six isolates had a count a 3–43 bacteria g-1 count using MPN; 7.7% exceeded the Argentine Food Code (CAA) limit. All isolates showed protease activity: enterotoxigenic isolates had higher protease activity than non-enterotoxigenic isolates. All isolates showed azoreductase activity: enterotoxigenic isolates had higher activity and shorter reducing times. Enterotoxigenic isolates showed chromosomal location for the gene responsible for the enterotoxin.Fil: Corigliano, Mariana Georgina. Universidad Nacional de San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Guzmán, Ana María Stefanini. Universidad Nacional de San Luis; ArgentinaFil: Stagnitta, Patricia Virginia. Universidad Nacional de San Luis; Argentin

A photoluminescence study of C60 and C70

The luminescence spectra of C60 and C70 have been recorded in glassy toluene solution at 77 K and as neat solids at 5 K. The C70 spectrum consists of two band systems each with resolved vibronic structure. The red system of C70 begins at 15012 cm-1, exhibits a lifetime of 1 --> S0 fluorescence. The infrared emission system begins at 12614 cm-1, decays with a 30 ms lifetime and is assigned as T1 --> S0 phosphorescence. A weak luminescence maximum at 13579 cm-1 is assigned tentatively as the S1 --> S0 fluorescence of C60.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30243/1/0000638.pd

Telescoped approach to aryl hydroxymethylation in the synthesis of a key pharmaceutical intermediate

An efficient synthetic approach leading to introduction of the hydroxymethyl group to an aryl moiety via combination of the Bouveault formylation and hydride reduction has been optimized using a rational, mechanistic-based approach. This approach enabled telescoping of the two steps into a single efficient process, readily amenable to scaleup

Des confusions babéliennes, des sauvageries, des soumissions

Le mythe de Babel met en scène des hommes essayant d'assouvir leur désir de gloire et de puissance, et surtout, de se transcender, alors même qu'il leur est impossible de se détacher de leur essence. Pour cette audace, Dieu les punit en les « confondant » à travers leur moyen d'expression : la langue. En multipliant les langues, Dieu divise les hommes et annihile chez eux toute ambition de dépassement. Les processus contemporains comme la mondialisation ou bien l'usage des nouveaux moyens de communications peuvent bien être incontrôlables et imprévisible.  Ceux-ci font se poser d'une façon toute nouvelle l'éternelle question de l'évolution, des transformations, et peut-être de l'uniformisation des cultures humaines. Evoquer la possibilité d'une uniformisation culturelle à l'échelle de la planète peut nous apparaître paradoxal dans un monde où l'on échange autant, où la mise en valeur et la construction des identités complexifie chaque jour d'avantage le jeu social. Ce double mouvement, entre dynamiques centrifuges qui unissent et divisent, identifient, semble être devenu un aspect essentiel à saisir pour décrire notre époque. L'identité de l'individu postmoderne devient le terrain de toutes les luttes de pouvoirs, où l'on ne cherche plus non seulement à conquérir les territoires, les ressources, mais aussi les esprits et les cœurs, et toujours, moyennant une arme/outil toute puissante : la langue

Effect of Emamectin Benzoate on Mortality, Proboscis Extension, Gustation and Reproduction of the Corn Earworm, Helicoverpa zea

Newly emerged corn earworm adults, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) require a carbohydrate source from plant or other exudates and nectars for dispersal and reproduction. Adults actively seek and forage at feeding sites upon eclosion in the habitat of the larval host plant or during dispersal to, or colonization of, a suitable reproductive habitat. This nocturnal behavior of H. zea has potential for exploitation as a pest management strategy for suppression using an adult feeding approach. This approach entails the use of a feeding attractant and stimulant in combination with a toxicant that when ingested by the adult will either reduce fecundity/fertility at sub-lethal dosages or kill the adult. The intent of this study was to assess reproductive inhibition and toxicity of emamectin benzoate on H. zea when ingested by the adults when mixed in ppm active ingredient (wt:vol) with 2.5 M sucrose as a feeding stimulant. Because the mixture has to be ingested to function, the effect of emamectin benzoate was also evaluated at sub-lethal and lethal concentrations on proboscis extension and gustatory response of H. zea in the laboratory. Feral males captured in sex pheromone-baited traps in the field were used for toxicity evaluations because they were readily available and were more representative of the field populations than laboratory-reared adults. Laboratory-reared female moths were used for reproduction effects because it is very difficult to collect newly emerged feral females from the field. Emamectin benzoate was highly toxic to feral H. zea males with LC50 values (95% CL) being 0.718 (0.532–0.878), 0.525 (0.316–0.751), and 0.182 (0.06–0.294) ppm for 24, 48 and 72 h responses, respectively. Sub-lethal concentrations of emamectin benzoate did not significantly reduce proboscis extension response of feral males and gustatory response of female H. zea. Sublethal concentrations of emamectin benzoate significantly reduced percent larval hatch of eggs and mating frequency of female H. zea. Larval survival to the pupal stage was also significantly reduced by ingestion of emamectin benzoate by female H. zea. These data suggest that emamectin benzoate is a useful toxicant in an attract-and-kill control strategy against H. zea. Field studies are warranted to validate the results reported in this study