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131.
Four pop-out search experiments investigated whether dimension-based visual attention is top-down modulable. Observers searched for singleton feature targets defined, variably across trials, by a color or an orientation difference to nontargets. Observers were precued to the most probable target-defining dimension (e.g., by the word color) or feature (red) on a given trial. Results revealed expedited reaction times (RTs) for valid-dimension targets relative to neutral-cue conditions, and slowed RTs for invalid-dimension targets. Cue information as to precise target feature yielded some extra effect only for color targets. The dimensional cuing significantly reduced, but did not abolish, the dimension-specific influence of the previous target on detection of the current target (same-dimension RT  相似文献   
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Fibre-optic supertrunking has a well-established place in larger CATV networks. Supertrunks have to be transparent to the quality of the transmitted TV signals and they have to have a negligible impact on the system reliability of the total network. At least 60 dB (weighted) video SNR has to be achieved and down times of less than one hour per year per fibre are desirable. AM on fibre can achieve these goals only in shorter supertrunks. FM and digital modulation techniques with a higher loss budget than AM are well suited for high transmission quality as well as for redundant supertrunk topologies, achieving excellent system availability numbers at the expense of increased equipment complexity.  相似文献   
134.
The effects of temperature and photoperiod on accumulation of hydroxamic acids (Hx) in wheat (Triticum aestivum L.) seedlings were evaluated under laboratory conditions. Hx concentrations were significantly higher at higher temperatures. No such clear trend was found for the photoperiod effect. The significant effect of temperature and photoperiod on growth rate of seedlings and the significant positive correlation between growth rate prior to analysis and levels of Hx, suggested that environmental effects on Hx accumulation were at least partially mediated through their effect on plant growth rate. After uncoupling the effect of environmental conditions from the effect of plant growth rate by statistical means the effect of temperature on Hx was no longer significant. Therefore, temperature effect was fully mediated by plant growth rate. Implications of the patterns found are discussed in issues of plant-defense general theories.  相似文献   
135.
This paper presents two generalized modified OS-CFAR detectors and an automatic censoring technique. For these two new OS-CFAR detectors, analytic expressions of the false alarm rate, the detection probabilities and the measure of ADT under the Swerling 2 assumption are obtained. Their detection performances are analyzed in homogeneous background and in the presence of strong interfering targets, and they are compared with several previously proposed CFARs.  相似文献   
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Participants made judgments about the relative salience of category exemplars (e.g., fruit: apple or grape) or parts (e.g., plane: wings or seats). Mildly affected Alzheimer's disease (AD) patients were as accurate but slower than normal controls, and their response times increased more for related (e.g., apple, grape, or fig) than unrelated (e.g., apple, gym, bandit) choices as the number of alternatives was increased from 2 to 3. Performance (accuracy and response times) of moderate-severely affected patients was poorer still, but number of distractors and relatedness did not interact. In combination with previous findings (e.g., M. K. Johnson, A. M. Hermann, & J. L. Bonilla, 1995), these results suggest that the reflective processes necessary for deciding among competing alternatives show disruption early in the disease process. Such processing deficits would compound any difficulties arising from a degrading semantic structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
138.
Mal d 2, a thaumatin-like protein from apple was previously described to react to almost 75% of the apple allergic patient sera. Based on the molecular structure of this protein, the present study focused on the conformational stability of Mal d 2 in relation to in vitro IgE-binding under different physico-chemical conditions and proteolysis. The structural integrity of Mal d 2 was monitored using SDS–PAGE, Western blotting using polyclonal antibodies and human sera, fluorescence spectrometry and circular dichroism. Results confirmed the stability of Mal d 2. However, Mal d 2 was reactive to human serum IgEs mainly after reduction of disulphide bridges fixing the α-helical domain II. Contrary to previous assumptions, the current findings suggest that the allergenic epitopes of Mal d 2 are hidden inside the protein structure and none of the rigorous conditions applied in industrial juice processing or digestive proteolysis enhance or reduce the binding to IgE molecules.  相似文献   
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