Ethene/norbornene copolymerization by [Me_2Si(3-~(tert)BuCp)(N~(tert)Bu)]TiCl_2/MAO-catalyst     

TRAN Phu-Dennis  KAMINSKY Walter 《Journal of Zhejiang University. Science. B》2003,(2)

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Artificial grammar learning in pigeons     

Herbranson WT  Shimp CP 《Learning & behavior》2008,36(2):116-137

In two experiments, we developed a new methodology for studying complex stimulus control by spatial sequences of letters generated by artificial grammars. An artificial grammar is a system of rules that defines which letter sequences or strings are “grammatical.” In Experiment 1, pigeons learned to respond differently to strings conforming to a grammar versus strings that were nongrammatical distortions. Several different criteria all suggested that performance was controlled both by some short chunks of strings shared between reinforced training strings and novel transfer strings and by more complex sequential regularities. In Experiment 2, pigeons quickly and accurately learned to respond differently to strings conforming to one or the other of two different artificial grammars. As in Experiment 1, performance was controlled both by some short chunks and by more complex sequential regularities. The results are interpreted in terms of family resemblance and pose new goals for theories of complex stimulus control.  相似文献   

The relation of education and R&D to productivity growth     

Walter W. McMahon 《Economics of Education Review》1984,3(4):299-313

This paper considers the relation of education and of scientific and technical knowledge developed through R&D to labor productivity growth within the medium term. It is unique in using a total capital approach that includes both private and public physical, human, and knowledge capital formation and in use of a medium term model for determining productivity growth that includes both demand side and supply side effects. Empirical results for the U.S. and 14 other major OECD nations for 5-yr time periods from 1955 through 1980 find education as measured both by the average educational attainment of the labor force and by the percentage of advanced level graduates who bring technology to bear on production to be significant determinants of productivity growth. Gross investment in physical capital also transmits the R&D and has a positive influence, as do higher utilization rates and the technology transfer associated with lower initial productivity levels.  相似文献   

Learner control of context and instructional support in learning elementary school mathematics     

Gary R. Morrison  Steven M. Ross  Walter Baldwin 《Educational technology research and development : ETR & D》1992,40(1):5-13

Learner-control strategies for selecting problem context and the level of instructional support were examined separately and in combination on a computer-based mathematics unit on the metric system. Subjects were 240 sixth-grade students assigned to 15 treatments formed by crossing five context conditions (animals, sports, clothing, nocontext, and learner control) with three instructional support conditions (minimum, maximum, and learner control). As hypothesized, comparisons of instructional support conditions on posttest achievement showed performance to be lowest under learner control. Subjects opted to view very few items and to decrease the amount they selected over the course of the instruction. No effects were associated with the context variable, although on one of the three lessons, learner-control subjects made significantly fewer on-task errors than did no-context subjects. Further analyses showed a strong tendency by learner-control context subjects to vary their selection of contexts across lessons. Subjects in the context and instructional support learner-control strategies indicated positive attitudes toward the strategies.  相似文献   

Preference between fixed-interval and variable-interval schedules of reinforcement: Separate roles of temporal scaling and predictability     

Paul W. Frankel  Walter Vom Saal 《Learning & behavior》1976,4(1):71-76

Pigeons’ preference between fixed-interval and variable-interval schedules was examined using a concurrent-chains procedure. Responses to two concurrently available keys in the initial links of the concurrent chains occasionally produced terminal links where further responses were reinforced under either a fixed- or variable-interval schedule. In previous studies, preferences for the variable schedule with such a procedure have been interpreted as reflecting atemporal scaling process that heavily weights the shorter intervals in the variable schedule. The present experiment examined whetherpredictability, i.e., the presence of external stimuli correlated with the reinforcement interval, might also influence preference in such situations. When the two intervals in a variable schedule were made predictable by being associated with different key colors, preference for that schedule increased. This increase was reliable but small in magnitude and transient when initial-link responses only occasionally produced terminal links; it was large in magnitude when only one response in the initial link was required to produce the appropriate terminal-link schedule. The results suggest that preference between fixed and variable schedules may be influenced both by temporal scaling and to a lesser extent by predictability of the reinforcement intervals.  相似文献   

Financial Aid and College Persistence: Do Student Loans Help or Hurt?     

Serge Herzog 《Research in higher education》2018,59(3):273-301

Using data from two freshmen cohorts at a public research university (N = 3730), this study examines the relationship between loan aid and second-year enrollment persistence. Applying a counterfactual analytical framework that relies on propensity score (PS) weighting and matching to address selection bias associated with treatment status, the study estimates that loan aid exerts a significant negative effect on persistence for students from low-income background (i.e., Pell eligible), and those taking up high amounts of loans in order to meet total cost of attendance, including students who exhausted the available amount of subsidized loan aid. However, no significant incremental effect associated with unsubsidized loan aid, net of subsidized loan aid, could be detected. The estimated effect of loan aid on persistence controls for first-year academic experience and takes into account 26 factors related to loan selection and persistence in order to match students with loan aid to a counterfactual case in covariate adjusted regression. Comparison with results from non-matched-sample analysis suggests selection bias may mask the negative effect of loans detected with matched-sample estimation. Validity of covariates determining the loan selection process and criteria for acceptable balance in the matched data are discussed, and implications for future research are addressed.  相似文献   

Modeling black student academic performance in higher education     

A. Wade Smith  Walter R. Allen 《Research in higher education》1984,21(2):210-225

Recent research has noted differences in the predictive efficacy of educational attainment models produced for whites as opposed to blacks; and called for more resolution in the findings on blacks in advance of further comparative analyses. The National Study of Black College Students (NSBCS) is employed to develop a model that distinguishes between high- and low-performing black undergraduates attending public, four-year institutions. In the NSBCS sample (N=695), discriminant function analysis identifies several institutional and student characteristics which are related to black students' educational outcomes. Specifically, students with both high occupational aspirations and high academic performances tend to be male, attend comparatively larger schools, and, to a lesser degree, be relatively well-adjusted upperclassmen. When academic performance is the sole issue, it is positively correlated with institutional quality, but the advantage belongs to black females. Contrary to the suggestions of previous research, black community sentiment did not have relationships with educational outcomes to the extent expected. These results suggest that future models of black educational attainment marry traditional Wisconsin-type measures with institutional and student attributes.An earlier version of this paper was presented at the 1983 meetings of the American Sociological Association, Detroit, Mich.  相似文献   

Changing the Attitudes That Predict Underage Drinking in College Students: A Program Evaluation     

David J. Williams  Adrian Thomas  Walter C. Buboltz  Maribel McKinney 《Journal of College Counseling》2002,5(1):39-49

Several attitudes that predicted binge drinking on campus were identified by focus groups. A brief classroom intervention led to self‐reported attitude change among university students. This type of intervention may be useful to college counselors interested in redefining normative perceptions of alcohol use to decrease the prevalence of binge drinking.  相似文献   

Situating Special Educators’ Instructional Quality and Their Students’ Outcomes within the Conditions Shaping Their Work     

Elizabeth Bettini  Yujeong Park  Amber Benedict  Jenna Kimerling  Walter Leite 《Exceptionality》2016,24(3):176-193

This investigation examined relationships among special education teachers’ working conditions (e.g., classroom characteristics, administrative support), personal characteristics (e.g., experience, certification status, self-efficacy), instructional quality, and students with disabilities’ reading achievement and behavioral outcomes. Data from the 2004–2005 administration of the Special Education Elementary Longitudinal Study were used. Confirmatory factor analysis was used to test the fit of models for five latent factors. Hybrid structural models were applied to test the hypothesis that working conditions would be positively associated with special education teachers’ self-efficacy and their instructional quality, which would, in turn, be positively associated with their students’ reading achievement and behavioral outcomes. Although the initial structural equation model tested failed to support the hypotheses, several significant relationships with theoretical and practical significance were discovered. Directions for future research and practical implications are discussed.  相似文献   

Understanding patterns of evolution acceptance—A new implementation of the Measure of Acceptance of the Theory of Evolution (MATE) with Midwestern university students          下载免费PDF全文

William L. Romine  Emily M. Walter  Ephiram Bosse  Amber N. Todd 《科学教学研究杂志》2017,54(5):642-671

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