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21.
The role of MHC class II in the presentation of Heligmosomoides polygyrus antigens has been investigated, using a number of T cell hybridomas produced in A and E positive and negative mice. By using fixed and irradiated antigen presenting cells (APC), further evidence has emerged, to support earlier data, that there can be differential processing requirements during the presentation of H. polygyrus antigens by A and E molecules. In concordance with these earlier observations, this work provides further evidence than individual T cells can respond to antigen when presented by more than one MHC molecule. Previously, this evidence has been restricted to individual MHC molecules of the same haplotype, but these data show that H. polygyrus produces antigens which can be presented by both syngeneic and allogeneic MHC molecules. These antigens do not appear to be synonymous with the previously described H. polygyrus superantigen, as presentation is restricted to specific MHC haplotypes. It is proposed that H. polygyrus may produce these antigenic molecules as part of its strategy to manipulate the host immune system. 相似文献
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Two experiments involving 99 undergraduate participants sought to examine the influence of mood states on encoding speed within lexical decision and pronunciation tasks. Mood states were measured naturalistically in Experiment 1 and manipulated in Experiment 2. Stimuli consisted of nouns representing useful (e.g., food) and nonuseful (e.g., lint) objects. Mood states had no implications for initial encoding speed. However, when the same words were presented a 2nd time (i.e., repeated), happy individuals displayed a tendency to encode useful words faster than nonuseful ones. Thus, mood states influenced repetition priming on the basis of stimulus valence. The authors propose that happiness sensitizes individuals to useful or rewarding objects, which in turn creates a stronger memory trace for such stimuli in the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
M. L. Newman B. J. Robinson H. Sehitoglu J. A. Dantzig 《Metallurgical and Materials Transactions A》2003,34(7):1483-1491
A study of the development of deformation and transient and residual stresses during quenching in aluminum alloy W319 is presented.
Rapid tension tests were performed on W319 in the super-saturated solution state at several temperatures and strain rates.
A material model following the mechanical threshold stress (MTS)-Voce formulation is developed and implemented in both a simple
one-dimensional code and a fully three-dimensional form as a user material subroutine in ABAQUS. The results of the tension
tests are used to determine the parameters in the thermomechanical constitutive model. Unidirectional beam quenching experiments
are performed to test the applicability of the constitutive model. Residual stresses in the beams are measured using a groove
removal technique upon completion of the quenching process. Residual stress and deformation results from beam quenching experiments
compare well to the analytical results computed using the constitutive model. 相似文献
25.
Empirical and theoretical evidence for the concept of working memory is considered. We argue that the major weakness of this concept is its loose connection with the knowledge about background perceptive and cognitive processes. Results of two relevant experiments are provided. The first study demonstrated the classical chunking effect in a speeded visual search and comparison task, the proper domain of a large-capacity very short term sensory store. Our second study was a kind of extended levels-of-processing experiment. We attempted to manipulate visual, phonological, and (different) executive components of long-term memory in the hope of finding some systematic relationships between these forms of processing. Indeed, the results demonstrated a high degree of systematicity without any apparent need for a concept such as working memory for the explanation. Accordingly, the place for working memory is at all the interfaces where our metacognitive strategies interfere with mostly domain-specific cognitive mechanisms. Working memory is simply our work with memory. 相似文献
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27.
Numerical Modeling of Silicon Photodiodes for High-Accuracy Applications Part I. Simulation Programs
Jon Geist Deane Chandler-Horowitz A. M. Robinson C. R. James 《Journal of research of the National Institute of Standards and Technology》1991,96(4):463-469
The suitability of the semiconductor-device modeling program PC-1D for high-accuracy simulation of silicon photodiodes is discussed. A set of user interface programs optimized to support high-accuracy batch-mode operation of PC-1D for modeling the internal quantum efficiency of photodiodes is also described. The optimization includes correction for the dark current under reverse- and forward-bias conditions before calculating the quantum efficiency, and easy access to the highest numerical accuracy available from PC-1D, neither of which is conveniently available with PC-1D’s standard user interface. 相似文献
28.
Records of 60 patients with primary salivary gland tumors were retrospectively analyzed. Most were European Jews, 60% were males, and the average age was 57 years. The parotid gland was the most frequent site of origin (76%). The main presenting symptom was painless swelling. Pain or facial palsy were rare and associated with poor prognoses. The most common types were mucoepidermoid, adenocystic, adenocarcinoma and malignant, mixed carcinomas (in descending order of frequency). Squamous cell carcinoma was the most prevalent histologic type. Most patients presented at an advanced stage. Treatment was mainly surgical and postoperative radiotherapy was given to those with advanced disease. Most recurrences occurred within 3 years of initial treatment. Actuarial 10-year survival for all patients was 40%. Superior survival rates were achieved in women, probably due to less aggressive malignancies. Low grade mucoepidermoid carcinoma had a favorable prognosis, whereas anaplastic carcinoma had the worst. Other significant prognostic factors included stage and grade of disease. 相似文献
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30.
A suggested method of estimation for spatial interdependent models with autocorrelated errors,and an application to a county expenditure model 总被引:3,自引:0,他引:3
The purpose of this paper is two-fold. First, we describe an estimation procedure that should be useful for spatial models which contain interactions between the dependent variables and autocorrelated error terms. Second, we apply that procedure to a spatial model relating to county police expenditures. Our estimation procedure does not require the specification of the error distribution, and its computational burden is modest. Large sample results are given. 相似文献