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51.
Tested the hypothesis that poor performance among schizophrenics (SCZs) is associated with less orienting to task-relevant stimuli and more orienting to task-irrelevant stimuli, interpreting the orienting response as a call for controlled processing resources. 32 SCZs (aged 20–65 yrs) and 32 age- and sex-matched controls were exposed to a signaled reaction time (RT) task in which one tone was followed by an imperative noise stimulus and a different tone signaled nothing. During one phase of the experiment, distracting visual stimuli were presented both between and during RT trials. Controls differentiated between the signal and nonsignal tones in all measures and showed rapid habituation to the distracting visual stimuli. The SCZs showed slow RTs, less overall responding than controls, and limited differential responses to signal and nonsignal stimuli. For the responses to visual distractors, however, the SCZs showed significantly slower habituation than the controls, confirming their inefficient orienting style. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
52.
Dorothea F K Rawn Sue C Quade J Brian Shields Giacomo Conca Wing-Fung Sun Gladys M A Lacroix Mark Smith André Fouquet André Bélanger 《Food Additives & Contaminants》2007,24(2):149-155
Apple trees in an orchard in Quebec, Canada were treated, following label directions, with the fungicide captan (1,2,3,6-tetrahydro-N-(trichloromethylthio)phthalimide) during the 2003 agricultural season. A total of 142 apples from three rows of trees were selected for determination of captan by GC/MS. Individual apples were found to contain captan levels ranging from 16.9 to 6350 ng g-1. Only two individual apple samples exceeded the Canadian maximum residue limit (5000 ng g-1) for captan in apples. Six composite samples, comprising half portions of eight individual apples, were analysed from each of the three experimental rows. Composite samples ranged in concentration from 166 to 2620 ng g-1. The greatest uncertainty associated with the measured concentrations was due to variability among apples rather than the measurement of residue levels. 相似文献
53.
Junction leakage current degradation under high temperature reverse-bias stress induced by band-defect-band tunnelling in power VDMOS 总被引:2,自引:0,他引:2
A deep analysis of the intrinsic junction and surface currents in power vertically diffused MOS devices with sub-micrometer channel length and thin gate oxide has been carried on after a typical reliability high temperature reverse bias (HTRB) stress. A reference set of gated diodes has also been examined in order to better understand the onset and evolution of post-stress leakage degradation. A comparison among complete MOSs, single body diodes and enriched diodes allows to highlight the role played by the point defectivity both at gate interface and in the bulk silicon close to the junction surface. We found that the typical interface defects involved in the leakage degradation are shallow traps and can be de-populated simply by a thermally activated mechanism. More specifically, the main degradation mechanism relies to band-defect-band tunneling localized at the surface drain/body junction where an intrinsic n-i-p region evolves due to a bird’s beak lateral profile of the body diffusion. We have demonstrated that the most important contribution to the activation of the precursor defect sites is given by the transverse electrical field that develops just below the SiO2/Si interface within the n-i-p region during the stress. 相似文献
54.
55.
Marco Leonesio Paolo Parenti Alberto Cassinari Giacomo Bianchi 《The International Journal of Advanced Manufacturing Technology》2014,72(9-12):1347-1360
In this paper, a particular kind of non-regenerative instability in surface grinding is studied. Clear evidences have been collected suggesting that vibrations can occur suddenly even during the first grinding pass, just after wheel dressing. These circumstances exclude workpiece and wheel surface regeneration as instability origin, whereas both surfaces have to be considered initially smooth. On these bases, the stability of the dynamic system constituted by an oscillating ideal wheel (namely without waviness on the surface) immerged in a positional and velocity-dependent process force field has been studied, demonstrating that, under particular conditions, the force field generates an unstable behaviour. The instability occurrence is strictly related to the oscillation direction of the wheel centre, according to the mode shape associated to the dominant resonance, with respect to the direction of the grinding force (identified by the ratio between its tangential and normal components). The analysis leads to the identification of a simple necessary condition for instability occurrence. The analytical results are confirmed by time-domain grinding simulations and compared with experimental evidences. 相似文献
56.
We have constructed new yeast vectors for targeted integration and conditional expression of any sequence at the Saccharomyces cerevisiae TYR1 locus which becomes disrupted. We show that vector integration is not neutral, causing prototrophy for tyrosine and auxotrophy for the vector's selectable marker (uracil or leucine, depending on the vector used). This feature allows a double screening of transformed yeast cells, improving the identification of colonies with the desired chromosomal structure. The GAL10 gene promoter has been added to drive conditional expression of cloned sequences. Using these vectors, chromosomal structure verification of recombinant clones is no longer necessary, since the noise of non-homologous recombination, as well as spontaneous reversion of the selected phenotype, can easily be identified. The ability of the vector to conditionally control gene expression has been confirmed using the gene for the green fluorescent protein (GFP) as a reporter. 相似文献
57.
Carlo Beatrice Chiara Guido Pierpaolo Napolitano Silvana Di Iorio Nicola Del Giacomo 《Fuel》2011,90(5):2039-2044
Results of a research project aimed at studying the capability to develop a method (economic and simple) for on-board biodiesel blending detection are described. The method is based on the direct measurement of the Indicated Mean Effective Pressure (IMEP).The study was carried out on a 2.0L four-cylinder “torque-controlled” Euro 5 diesel engine for passenger car (PC) application. This engine, equipped with instrumented glow plug for combustion closed-loop control, represents the state of the art of the diesel engine control technology.Two biodiesels were chosen for the experiments: a rapeseed methyl-ester (RME) and an aged RME, while the conventional diesel fuel was an European (EU) certification diesel fuel.Results indicate generally a good response in blending detection of the method. However, in order to attain an acceptable accuracy, a pre-calibration appears necessary. 相似文献
58.
For nearly a century, bereavement theorists have assumed that recovery from loss requires a period of grief work in which the ultimate goal is the severing of the attachment bond to the deceased. Reviews appearing in the 1980s noted a surprising absence of empirical support for this view, thus leaving the bereavement field without a guiding theoretical base. In this article, the authors consider alternative perspectives on bereavement that are based on cognitive stress theory, attachment theory, the social functional account of emotion, and trauma theory. They then elaborate on the most promising features of each theory in an attempt to develop an integrative framework to guide future research. The authors elucidate 4 fundamental components of the grieving process—context, meaning, representations of the lost relationship, and coping and emotion-regulation processes—and suggest ways in which these components may interact over the course of bereavement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
59.
Zirconium and hafnium oxide interface with silicon: Computational study of stress and strain effects
Computations of the periodic double-interface MO2/Si (M = Zr and Hf) systems using density functional theory (DFT) demonstrate that very thin epitaxial MO2 layers at silicon (1 0 0) surface adopt anatase-like structure with six-coordinate M atoms, while tetragonal-like MO2 structure with seven-coordinated M atoms has a lower stability (metastable). This results from a closer match between Si(1 0 0) surface unit cell and anatase-like ZrO2 and HfO2 leading to the overall stress reduction if MO2 adopts the anatase-like structure on silicon. In agreement with the previous study of Gavartin et al. [Gavartin, Fonseca, Bersuker, Shluger, Microelectron. Eng. 80 (2005) 412–415] formation of oxygen vacancy at the interface is demonstrated to be lower than in bulk film. This result appears to be independent from the film or interface structure but originates from the energy balance between M–O, M–M, Si–O and M–Si bonds, as revealed by a simple molecular model. 相似文献
60.
Giacomo Goli Marco Fioravanti Rémy Marchal Luca Uzielli Simone Busoni 《Holz als Roh- und Werkstoff》2010,68(4):385-395
Peripheral milling of wood with up milling and down milling techniques is very well known from a geometrical point of view. However, in processing anisotropic materials such as wood, these geometrical aspects imply relevant differences when machining. In fact, milling of anisotropic material leads to different cutting geometries when up- or down-milling and when increasing or decreasing the depth of cut resulting in different grain orientations depending on the adopted process. In this paper, tests performed when processing Douglas Fir with different depths of cut and grain orientations are described. The cutting forces were measured, and the dependence of the cutting forces with respect on the cutting geometry are analysed and discussed. 相似文献