Capacité en matière de prise de décisions chez des récidivistes de conduite avec capacités affaiblies par l’alcool

Thomas G. Brown, Ph.D., co-directeur de recherche

Carbon (C-13) and nitrogen (N-15) translocation in a maize-Striga hermonthica association

The translocation of C and N in a maize-Striga hermonthica association was investigated at three rates of nitrogen application in a glasshouse experiment. The objectives were to measure the transfer of C and N from maize to S. hermonthica and to determine whether the amount of N in the growing medium affected the proportions of C and N transferred. Young plants of maize were labelled in a (CO2)-C-13 atmosphere and leaf tips were immersed in ((NH4)-N-15)(2)SO4 Solution. The Striga x N interaction was not significant for any of the responses measured. Total dry matter for infected maize was significantly smaller than for uninfected maize from 43 to 99 days after planting, but N application increased total dry matter at all sampling times. Infected maize plants partitioned 39-45 % of their total dry matter to the roots compared with 28-31 % for Uninfected maize. Dry matter of S. hermonthica was not affected by the rate of N applied. S. hermonthica derived 100 % of its carbon from maize before emergence, decreasing to 22-59 % thereafter; the corresponding values for nitrogen were up to 59 % pre-emergence and Lip to 100 % after emergence. The relative proportions of nitrogen depleted from the host (up to 10 %) were greater than those of carbon (maximum 1.2 %) at all times of sampling after emergence of the parasite. The results show that the parasite was more dependent on the host for nitrogen than for carbon.

Carbon (C-13) and nitrogen (N-15) translocation in a maize-Striga hermonthica association

The translocation of C and N in a maize-Striga hermonthica association was investigated at three rates of nitrogen application in a glasshouse experiment. The objectives were to measure the transfer of C and N from maize to S. hermonthica and to determine whether the amount of N in the growing medium affected the proportions of C and N transferred. Young plants of maize were labelled in a (CO2)-C-13 atmosphere and leaf tips were immersed in ((NH4)-N-15)(2)SO4 Solution. The Striga x N interaction was not significant for any of the responses measured. Total dry matter for infected maize was significantly smaller than for uninfected maize from 43 to 99 days after planting, but N application increased total dry matter at all sampling times. Infected maize plants partitioned 39-45 % of their total dry matter to the roots compared with 28-31 % for Uninfected maize. Dry matter of S. hermonthica was not affected by the rate of N applied. S. hermonthica derived 100 % of its carbon from maize before emergence, decreasing to 22-59 % thereafter; the corresponding values for nitrogen were up to 59 % pre-emergence and Lip to 100 % after emergence. The relative proportions of nitrogen depleted from the host (up to 10 %) were greater than those of carbon (maximum 1.2 %) at all times of sampling after emergence of the parasite. The results show that the parasite was more dependent on the host for nitrogen than for carbon.

Effects of dietary vitamin A concentration of roasted soybean inclusion on marbling, adipose cellularity, and fatty acid composition of beef

A feedlot trial was conducted to determine the effect of dietary vitamin A concentration and roasted soybean (SB) inclusion on carcass characteristics, adipose tissue cellularity, and muscle fatty acid composition. Angus-crossbred steers (n = 168; 295 +/- 1.8 kg) were allotted to 24 pens (7 steers each). Four treatments, in a 2 x 2 factorial arrangement, were investigated: no supplemental vitamin A, no roasted soybeans (NANS); no vitamin A, roasted SB (20% of the diet on a DM basis; NASB); with supplemental (2,700 IU/kg) vitamin A, no roasted SB (WANS); and with supplemental vitamin A, roasted SB (WASB). Diets included high moisture corn, 5% corn silage, 10 to 20% supplement, and 20% roasted SB in the SB treatments on a DM basis. The calculated vitamin A concentration in the basal diet was < 1,300 IU/kg of DM. Blood samples (2 steers/pen) were collected for serum vitamin A determination. Steers were slaughtered after 168 d on feed. Carcass characteristics and LM composition were determined. Fatty acid composition of LM was analyzed, and adipose cellularity in the i.m. and s.c. depots was determined. No vitamin A x SB interactions were detected (P > 0.10) for cattle performance, carcass composition, or muscle fatty acid composition. Low vitamin A diets (NA) did not affect (P > 0.05) ADG, DMI, or G:F. Quality grade tended (P = 0.07) to be greater in NA steers. Marbling scores and the percentage of carcasses grading > or = Choice(-) were 10% greater for NA steers, although these trends were not significant (P = 0.11 and 0.13, respectively). Backfat thickness and yield grade were not affected (P > 0.26) by vitamin A supplementation. Composition of the LM was not affected (P > 0.15) by vitamin A or SB supplementation. Serum retinol at slaughter was 44% lower (P < 0.01) for steers fed NA than for steers supplemented with vitamin A (23.0 vs. 41.1 microg/dL). A vitamin A x SB interaction occurred (P < 0.05) for adipose cellularity in the i.m. depot; when no SB was fed, vitamin A supplementation decreased cell density and increased cell size. However, when SB was fed, vitamin A supplementation did not affect adipose cellularity. Adipose cellularity at the s.c. depot was not affected (P > 0.18) by vitamin A or SB treatments. Fatty acid profile of the LM was not affected by vitamin A (P > 0.05), but SB increased (P < 0.05) PUFA (7.88 vs. 4.30 g/100 g). It was concluded that feeding NA tended to increase marbling without affecting back-fat and yield grade. It appeared that NA induced hyperplasia in the i.m. but not in the s.c. fat depot.

Effect of species and genotype on the efficiency of enrichment of poultry meat with n-3 polyunsaturated fatty acids

The effect of poultry species (broiler or turkey) and genotype (Wrolstad or BUT T8 turkeys and Ross 308 or Cobb 500 broilers) on the efficiency with which dietary longchain n-3 PUFA were incorporated into poultry meat was determined. Broilers and turkeys of both genotypes were fed one of six diets varying in FA composition (two replicates per genotype x diet interaction). Diets contained 50 g/kg added oil, which was either blended vegetable oil (control), or partially replaced with linseed oil (20 or 40 g/kg diet), fish oil (20 or 40 g/kg diet), or a mixture of the two (20 g linseed oil and 20 g fish oil/kg diet). Feeds and samples of skinless breast and thigh meat were analyzed for FA. Wrolstad dark meat was slightly more responsive than BUT T8 (P = 0.046) to increased dietary 18:3 concentrations (slopes of 0.570 and 0.465, respectively). The Ross 308 was also slightly more responsive than the Cobb 500 (P= 0.002) in this parameter (slopes of 0.557 and 0.449). There were no other significant differences between the genotypes. There was some evidence (based on the estimates of the slopes and their associated standard errors) that white turkey meat was more responsive than white chicken meat to 20:5 (slopes of 0.504 and 0.289 for turkeys and broilers, respectively). There was no relationship between dietary 18:3 n-3 content and meat 20:5 and 22:6 contents. If birds do convert 18:3 to higher FA, these acids are not then deposited in the edible tissues.

Carbon (13C) and nitrogen (15 N) translocation in a maize-striga hermonthica association

The translocation of C and N in a maize-Striga hermonthica association was investigated at three rates of nitrogen application in a glasshouse experiment. The objectives were to measure the transfer of C and N from maize to S. hermonthica and to determine whether the amount of N in the growing medium affected the proportions of C and N transferred. Young plants of maize were labelled in a (CO2)-C-13 atmosphere and leaf tips were immersed in ((NH4)-N-15)(2)SO4 Solution. The Striga x N interaction was not significant for any of the responses measured. Total dry matter for infected maize was significantly smaller than for uninfected maize from 43 to 99 days after planting, but N application increased total dry matter at all sampling times. Infected maize plants partitioned 39-45 % of their total dry matter to the roots compared with 28-31 % for Uninfected maize. Dry matter of S. hermonthica was not affected by the rate of N applied. S. hermonthica derived 100 % of its carbon from maize before emergence, decreasing to 22-59 % thereafter; the corresponding values for nitrogen were up to 59 % pre-emergence and Lip to 100 % after emergence. The relative proportions of nitrogen depleted from the host (up to 10 %) were greater than those of carbon (maximum 1.2 %) at all times of sampling after emergence of the parasite. The results show that the parasite was more dependent on the host for nitrogen than for carbon.

CCL3, acting via the chemokine receptor CCR5, leads to independent activation of Janus kinase 2 (JAK2) and G(i) proteins

The interaction of the chemokine receptor, CCR5, expressed in recombinant cells, with different G proteins was investigated and CCR5 was found to interact with G(i), G(o) and G(q) species. Interaction with Gi leads to G protein activation, whereas G. does not seem to be activated. Additionally, CCR5 activation also leads to phosphorylation of Janus kinase 2 (JAK2). Activation of JAK2 is independent of Gi or Gq activation. Gi protein activation was not prevented by inhibition of JAK, showing that heterotrimeric G protein activation and activation of the JAK/signal transducer and activator of transcription (STAT) pathway are independent of each other. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Increased n-6 polyunsaturated fatty acids do not attenuate the effects of long-chain n-3 polyunsaturated fatty acids on insulin sensitivity or triacylglycerol reduction in Indian Asians

Background: Indian Asians in Western countries have a higher rate of coronary artery disease than do the indigenous white populations, and this higher rate may be influenced by a dietary imbalance of n-6 and n-3 polyunsaturated fatty acids (PUFAs). Objective: The objective of the study was to test the hypothesis that a high background dietary intake of n-6 PUFA attenuates the effects of fish-oil supplementation on insulin sensitivity and associated blood lipids of the metabolic syndrome. Design: Twenty-nine Indian Asian men were recruited to participate in a 12-wk dietary intervention trial. Volunteers were randomly assigned to receive either a moderate or a high n-6 PUFA diet featuring modified oils and spreads over a 6-wk period. After this 6-wk period, both groups were supplemented with 4.0 g fish oil/d (2.5 g eicosapentaenoic acid + docosahexaenoic acid) for an additional 6 wk in combination with the dietary treatment. Volunteers participated in a postprandial study and an insulin sensitivity test after the 6-wk dietary intervention and again after the fish-oil supplementation period. Results: There was no significant time X treatment interaction for blood lipids or insulin action after dietary intervention with the moderate or high n-6 PUFA diets in combination with fish oil. After the 6-wk period of fish oil supplementation, fasting and postprandial plasma triacylglycerol concentrations decreased significantly. Conclusion: The background dietary n-6 PUFA concentration did not modulate the effect of fish-oil supplementation on blood lipids or measures of insulin sensitivity in this ethnic group.

The role played by the interaction between genetic factors and attachment in the stress response in infancy

Background: The importance of understanding which environmental and biological factors are involved in determining individual differences in physiological response to stress is widely recognized, given the impact that stress has on physical and mental health. Methods: The child-mother attachment relationship and some genetic polymorphisms (5-HTTLPR, COMT and GABRA6) were tested as predictors of salivary cortisol and alpha amylase concentrations, two biomarkers of hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic adrenomedullary (SAM) system activity, during the Strange Situation (SS) procedure in a sample of more than 100 healthy infants, aged 12 to 18 months. Results: Individual differences in alpha amylase response to separation were predicted by security of attachment in interaction with 5-HTTLPR and GABRA6 genetic polymorphisms, whereas alpha amylase basal levels were predicted by COMT x attachment interaction. No significant effect of attachment, genetics and their interaction on cortisol activity emerged. Conclusions: These results help to disentangle the role played by both genetic and environmental factors in determining individual differences in stress response in infancy. The results also shed light on the suggestion that HPA and SAM systems are likely to have different characteristic responses to stress.

Buyer–seller interaction in experimental spatial markets

We report results from experimental spatial markets with endogenous buyer location on a discrete version of Hotelling's linear city. Buyer locations favor more often the hypothesis of transportation cost minimization than that of strategic location aimed at increasing price competition between sellers. However, the latter of the two hypotheses receives systematic support too. Differentiation by seller-subjects is substantially less than the theory would predict for the specific framework used. Our results suggest that location strategies adopted by subjects can be seen as a rational process favoring conservative product design and spatial agglomeration of economic activities.

Knowledge effect on firm performance in manufacturing and service firms

This thesis seeks to examine the difference between manufacturing and service firms with respect to the effects of knowledge on performance, and the influence of market turbulence in this relationship. Empirical data, resulting from a survey, was collected from more than 1,206 firms, involving several sectors. Two samples were analyzed, one with 334 manufacturing and other with 509 service firms. The findings indicate no significant difference in the importance of knowledge on performance between these sectors in the absence of market turbulence: knowledge development (KD) has a stronger effect than culture of competitiveness (CC) on firm performance. However, under market turbulence, manufacturers differ from service providers. The positive effect of KD is enhanced, while the positive effect of CC remains the same for manufacturing firms. On the other hand, the positive effect of KD is diminished, while the positive effect of CC is enhanced for service firms. This supports the argument concerning differences in the nature of manufacturing and service industries. From a managerial point of view, results confirm the importance of knowledge, irrespective of firm sector or market turbulence. However, while industrial firms should center efforts on KD, service firms must find a balance where knowledge development (e.g. norms, processes, routines) does not impair their culture of competitiveness (e.g. learning, innovation, action). The thesis contributes to existing literature by proposing that: (1) the positive effect of knowledge on performance is confirmed; (2) under turbulent markets manufacturing and service firms have different responses concerning the influence of knowledge on performance; (3) a multidimensional performance construct based on cost, profitability, and growth is an interesting way to evaluate firm sustained competitive advantage, rather than one-dimensional constructs; (4) the CC x KD interaction, found relevant for supply chains in previous studies, is not supported for firms; (5) differences in unit of analysis, e.g. from supply chains to firms, result in different effects of KD and CC on firm performance; (6) existing scales can be improved with the addition of more diverse indicators, capturing a wider range of concepts (e.g. information transfer measurement); and (7) results from previous studies are supported for Brazilian firms, contributing for theory generalization.

Cloreto de mepiquat, thidiazuron e ethephon aplicados no algodoeiro em Ponta Porã, MS

O objetivo do presente estudo foi avaliar os efeitos de diferentes dosagens de cloreto de mepiquat, thidiazuron e ethephon, aplicadas parceladamente no algodoeiro (Gossypium hirsutum L.) na Fazenda Itamarati, Ponta Porã, MS. As dosagens de cloreto de mepiquat foram: (0; 12,5 + 12,5 + 25,0 = 50; 25 + 25 + 25 = 75; 0 + 50 + 50 = 100; 12,5 + 62,5 + 50 = 125) g ha-1, com aplicações efetuadas aos 34, 47 e 62 dias após a emergência (DAE) em 1993/94, e aos 42, 60 e 73 DAE, em 1994/95, enquanto o thidiazuron foi aplicado quando 70% dos capulhos estavam abertos, nas dosagens de 0, 45, 60 e 75 g ha-1; já o ethephon foi aplicado sete dias após o thidiazuron, quando já se observava desfolha de 85%, nas dosagens de 0, 960 e 1.440 g ha-1. O delineamento experimental utilizado foi o de blocos casualizados em faixa, com subparcelas subdivididas e quatro repetições. O cloreto de mepiquat proporcionou redução do número de frutos verdes, aumento do peso de 100 sementes e do peso médio de um capulho; a percentagem de desfolha aumentou com as dosagens de thidiazuron e ethephon; constatou-se que a interação cloreto de mepiquat x thidiazuron x ethephon foi significativa para percentagem de abertura de capulhos e produção de algodão em caroço.

Aporte de energia, composição e eficiência microbiana em bovinos alimentados com feno de capim-marandu e concentrado balanceados para diferentes ganhos de peso e potenciais de fermentação microbiana

Um experimento foi realizado com o objetivo de avaliar o aporte de energia, a composição de bactérias e a eficiência microbiana por tourinhos Santa Gertrudes canulados no rúmen e no duodeno alimentados com dietas compostas de feno de capim-marandu e concentrado. Empregou-se o delineamento em quadrado latino 4 &acute; 4, no qual os tratamentos foram concentrados ajustados para ganho de peso corporal (GPC) diário de 0,5 e 1 kg/animal e potencial de fermentação microbiana (y) de 9,5 e 11 g de PB microbiana/MJ energia metabolizável fermentável. Houve diferença para as concentrações de nutrientes digestíveis totais (NDT) e energia metabolizável fermentável (EMFe) ingeridos e para a composição em matéria orgânica e mineral das bactérias ruminais para as dietas ajustadas para diferentes GPC. Houve interação significativa GPC &acute; y para a ingestão de NDT como porcentagem do peso corporal e a composição em PB e carboidratos totais das bactérias ruminais. Não foram encontradas diferenças para os potenciais de fermentação microbiana. A eficiência de síntese microbiana também não diferiu entre as dietas e apresentou valores de 12,7 g PB microbiana/100 g NDT e 9,2 g PB microbiana/MJ EMFe. As diferenças encontradas não justificaram o balanceamento dos concentrados para os diferentes potenciais de fermentação microbiana avaliados.

Performance and morphology of intestinal mucosa of broilers fed mannan-oligosaccharides and enzymes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)