980 resultados para Role of managers


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This study examined the effects of political identity and the changing intergroup context on communication perceptions during an election campaign. Perceptions of media bias and of campaign impact on self and others were assessed before and after the election. The responses of politically aligned voters reflected their membership in a dominant or subordinate group preelection and in a losing or winning group postelection. Dominant group members were initially less biased in their views of the campaign and its impact but sought to blame their party's loss on media bias and on the gullibility of political out-group members and voters in general. Subordinate group members initially showed strong in-group-serving biases but were less critical of the media and the electorate after their party had won. Results highlight the dynamic, intergroup, nature of media perceptions.

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The aim of the study was to test a revised conceptualization of the role of coping in adjustment to a low-control stressor-women's adjustment to a failed in vitro fertilization (NF) attempt. Data were collected prior to the IVF treatment (Time I) and twice after the failed NF attempt (1 to 2 weeks after finding out the results, n = 171, and fi weeks later, n = 139). Initial adjustment was assessed at Time I, whereas measures of coping and both self-report and partner ratings of adjustment were obtained at Times ? and 3. As predicted, escapist strategies and problem-management strategies (mainly at Time ?) were associated with poor adjustment, whereas problem-appraisal coping was associated with better adjustment., There was also support for the proposed positive relationship between adjustment and emotional approach coping (on self-report adjustment).

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Frequency, recency, and type of prior exposure to very low-and high-frequency words were manipulated in a 3-phase (i.e., familiarization training, study, and test) design. Increasing the frequency with which a definition for a very low-frequency word was provided during familiarization facilitated the word's recognition in both yes-no (Experiment 1) and forced-choice paradigms (Experiment 2). Recognition of very low-frequency words not accompanied by a definition during familiarization first increased, then decreased as familiarization frequency increased (Experiment I). Reasons for these differences were investigated in Experiment 3 using judgments of recency and frequency. Results suggested that prior familiarization of a very low-frequency word with its definition may allow a more adequate episodic representation of the word to be formed during a subsequent study trial. Theoretical implications of these results for current models of memory are discussed.

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The three possible disulfide bonded isomers of alpha-conotoxin GI have been selectively synthesised and their structures determined by H-1 NMR spectroscopy. alpha-Conotoxin GI derives from the venom of Conus geographus and is a useful neuropharmacological tool as it selectively binds to the nicotinic acetylcholine receptor (nAChR), a ligand-gated ion channel involved in nerve signal transmission. The peptide has the sequence ECCNPACGRHYSC-NH2, and the three disulfide bonded isomers are referred to as GI(2-7;3-13), GI(2-13;3-7) and GI(2-3;7-13). The NMR structure for the native isomer GI(2-7;3-13) is of excellent quality, with a backbone pairwise RMSD of 0.16 Angstrom for a family of 35 structures, and comprises primarily a distorted 3(10),, helix between residues 5 to 11. The two non-native isomers exhibit multiple conformers in solution, with the major populated forms being different in structure both from each other and from the native form. Structure-activity relationships for the native GI(2-7;3-13) as well as the role of the disulfide bonds on folding and stability of the three isomers are examined. It is concluded that the disulfide bonds in alpha-conotoxin GI play a crucial part in determining both the structure and stability of the peptide. A trend for increased conformational heterogeneity was observed in the order of GI(2-7;3-13) < GI(2-13;3-7) < GI(2-3;7-13). It was found that the peptide bond joining Cys2 to Cys3 in GI(2-3;7-13) is predominantly trans, rather than cis as theoretically predicted. These structural data are used to interpret the varying nAChR binding of the non-native forms. A model for the binding of native GI(2-7;3-13) to the mammalian nAChR is proposed, with an alpha-subunit binding face made up of Cys2, Asn4, Pro5, Ala6 and Cys7 and a selectivity face, comprised of Arg9 and His10. These two faces orient the molecule between the alpha and delta subunits of the receptor. The structure of the CCNPAC sequence of the native GI(2-7;3-13) is compared to the structure of the identical sequence from the toxic domain of heat-stable enterotoxins, which forms part of the receptor binding region of the enterotoxins, but which has a different disulfide connectivity. (C) 1998 Academic Press Limited.

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Recent research has focused on the N-methyl-D-aspartate receptor system as a major site of ethanol action in the brain and specifically on compensatory changes in the expression of the polyamine-sensitive NR2B subunit. Therefore, we examined the effects of chronic ethanol treatment on polyamine homeostasis in the rat brain. Wistar rats were made dependent by ethanol vapor inhalation. This caused a rise in hippocampal ornithine decarboxylase (ODC) activity that was correlated with the appearance of physiological dependence. ODC activity returned to control levels within 3 days of ethanol withdrawal. Enzyme activity also increased in the cerebral cortex, striatum, and cerebellum of the ethanol-dependent rats. The concentration of the polyamines (putrescine, spermidine, and spermine) in the hippocampus was increased in ethanol-dependent rats. Injection of the ODC inhibitor, gamma-difluoromethylornithine (500 mg/kg) at the onset of withdrawal resulted in a significant reduction in the severity of withdrawal behaviors. The level of ODC activity and the severity of withdrawal behaviors were positively correlated. Perturbed polyamine homeostasis may represent an important molecular component in the initiation of ethanol withdrawal behaviors in the ethanol-dependent rat.

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Sixty-seven children aged 7 to 14 who met diagnostic criteria for an anxiety disorder were assigned to conditions according to parental anxiety level. Within these conditions, children were randomly assigned to I of 2 treatments: child-focused cognitive-behavioral therapy (CBT) or child-focused CBT plus parental anxiety management (CBT + PAM). At posttreatment, results indicated that within the child-anxiety-only condition, 82% of the children in the CBT condition no longer met criteria for an anxiety disorder compared with 80% in the CBT + PAM condition. Within the child + parental anxiety condition, 39% in the CBT condition no longer met criteria compared with 77% in the CBT + PAM condition. At follow-up, these differences were maintained, with some weakening over time. Results were not consistent across outcome measures. The interpretation and potential clinical implications of these findings are discussed.

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Ni catalysts supported on gamma-Al2O3, CeO2 and CeO2-A1(2)O(3) systems were tested for catalytic CO2 reforming of methane into synthesis gas. Ni/CeO2-Al2O3 catalysts showed much better catalytic performance than either CeO2- or gamma-Al2O3-supported Ni catalysts. CeO2 as a support for Ni catalysts produced a strong metal-support interaction (SMSI), which reduced the catalytic activity and carbon deposition. However, CeO2 had positive effect on catalytic activity, stability, and carbon suppression when used as a promoter in Ni/gamma-Al2O3 catalysts for this reaction. A weight loading of 1-5 wt% CeO2 was found to be the optimum. Ni catalysts with CeO2 promoters reduced the chemical interaction between nickel and support, resulting in an increase in reducibility and stronger dispersion of nickel. The stability and less coking on CeO2-promoted catalysts are attributed to the oxidative properties of CeO2. (C) 1998 Elsevier Science B.V. All rights reserved.

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Methadone maintenance treatment (MMT) involves the daily administration of the oral opioid agonist methadone as a treatment for opioid dependence-a persistent disorder with a substantial risk of premature death. MMT improves health and reduces illicit heroin use, infectious-disease transmission, and overdose death. However, its effectiveness is compromised if low maintenance doses of methadone (

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The effect of trace additions of magnesium on the sintering of aluminum and its alloys is examined. Magnesium, especially at low concentrations, has a disproportionate effect on sintering because it disrupts the passivating Al2O3 layer through the formation of a spinel phase. Magnesium penetrates the sintering compact by solid-state diffusion, and the oxide is reduced at the metal-oxide interface. This facilitates solid-state sintering, as well as wetting of the underlying metal by sintering liquids, when these are present. The optimum magnesium concentration is approximately 0.1 to 1.0 wt pet, but this is dependent on the volume of oxide and, hence, the particle size, as well as the sintering conditions. Small particle-size fractions require proportionally more magnesium than large-size fractions do.

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Two synthetic analogues of murine epidermal. growth factor, [Abu6, 20] mEGF4-48 (where Abu denotes amino-butyric acid) and [G1, M3, K21, H40] mEGF1-48, have been investigated by NMR spectroscopy. [Abu6, 20] mEGF4-48 was designed to determine the contribution of the 6-20 disulfide bridge to the structure and function of mEGF The overall structure of this analogue was similar to that of native mEGF, indicating that the loss of the 6-20 disulfide bridge did not affect the global fold of the molecule. Significant structural differences were observed near the N-terminus, however, with the direction of the polypeptide chain between residues four and nine being altered such that these residues were now located on the opposite face of the main beta-sheet from their position in native mEGF Thermal denaturation experiments also showed that the structure of [Abu6, 20] mEGF4-48 was less stable than that of mEGF. Removal of this disulfide bridge resulted in a significant loss of both mitogenic activity in Balb/c 3T3 cells and receptor binding on A431 cells compared with native mEGF and mEGF4-48, implying that the structural changes in [Abu6, 20] mEGF4-48, although limited to the N-terminus, were sufficient to interfere with receptor binding. The loss of binding affinity probably arose mainly from steric interactions of the dislocated N-terminal region with part of the receptor binding surface of EGF [G1, M3, K21, H40] mEGF1-48 was also synthesized in order to compare the synthetic polypeptide with the corresponding product of recombinant expression. Its mitogenic activity in Balb/c 3T3 cells was similar to that of native mEGF and analysis of its H-1 chemical shifts suggested that its structure was also very similar to native.

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During mouse embryogenesis, macrophage-like cells arise first in the yolk sac and are produced subsequently in the liver. The onset of liver hematopoiesis is associated with the transition from primitive to definitive erythrocyte production. This report addresses the hypothesis that a similar transition in phenotype occurs in myelopoiesis. We have used whole mount in situ hybridization to detect macrophage-specific genes expressed during mouse development. The mouse c-fms mRNA, encoding the receptor for macrophage colony-stimulating factor (CSF-1), was expressed on phagocytic cells in the yolk sac and throughout the embryo before the onset of liver hematopoiesis, Similar cells were detected using the mannose receptor, the complement receptor (CR3), or the Microphthalmia transcription factor (MITF) as mRNA markers. By contrast, other markers including the F4/80 antigen, the macrophage scavenger receptor, the S-100 proteins, S100A8 and S100A9, and the secretory product lysozyme appeared later in development and appeared restricted to only a subset of c-fms-positive cells. Two-color immunolabeling on disaggregated cells confirmed that CR3 and c-fms proteins are expressed on the same cells. Among the genes appearing later in development was the macrophage-restricted transcription factor, PU.1, which has been shown to be required for normal adult myelopoiesis. Mice with null mutations in PU.1 had normal numbers of c-fms-positive phagocytes at 11.5dpc. PU.1(-/-) embryonic stem cells were able to give rise to macrophagelike cells after cultivation in vitro. The results support previous evidence that yolk sac-derived fetal phagocytes are functionally distinct from those arising in the liver and develop via a different pathway. (C) 1999 by The American Society of Hematology.