Schedule-induced polydipsia contrast in the rat

Schedule-induced polydipsia was studied using a behavioral contrast paradigm. Food pellets were delivered to food-deprived rats on a response-independent FT 1-min schedule. Licking on a tube produced water on a MULT FR 10 FR 10, MULT FR 10 EXT, or MIXED FR 10 EXT for three rats (Experiment 1) and on a MULT VI VI, MULT VI EXT, or MIXED VI EXT schedule for three other rats (Experiment 2). On the FR schedules, rats could drink more water by increasing lick rates, but on the VI schedules the amount of drinking was fixed by the schedule parameters and was relatively unaffected by lick rates. Relative to MULT FR FR, positive polydipsia contrast was clearly demonstrated on MULT and MIXED FR EXT; but relative to MULT VI VI, contrast was not demonstrated on MULT and MIXED VI EXT. These data suggest that polydipsia contrast occurs only if increased licking permits increased drinking.     

Functional differentiation of adjunctive drinking and wheel running in rats

Food-deprived rats were exposed to a schedule in which a brief stimulus was presented approximately once every 60 sec. The first leverpress to occur in the presence of the stimulus always turned it off, and produced a food pellet 50% of the time. When the rats were given concurrent access to water, a running wheel, or both, drinking predominated during intervals initiated by pellet delivery, while running predominated during intervals initiated without food. When allowed to obtain all of their food pellets at the beginning of a session, rats drank less and ran more than when the intermittent schedule was in effect, and most drinking occurred within the first half of the session, while running was distributed throughout the session. Adjunctive drinking and wheel running appear to be functionally different, drinking being schedule-induced and food-bound, running being neither.     

机动车方向盘右置右行方案对安全的影响

以驾驶员视野分布理论为基础,通过对交通事故原因的分析,提出了方向盘右置机动车右行的方案。在统计数据的基础上,将新方案与传统的左置右行方案对可能产生的事故结果进行了对比,认为方向盘右置右行方案相对于左置右行方案,可降低机动车与非机动车之间的交通事故,减少伤亡人数。     

Schedule-induced behavior in rats: Pellets versus powder

Food-deprived rats develop polydipsia on an intermittent schedule (fixed time 60 sec) of food pellet delivery, but not on an identical schedule of food powder delivery. This result was demonstrated with separate groups receiving each type of food and was replicated using rats as their own controls. Powdered food not only prevented the development of polydipsia, but it abruptly terminated ongoing polydipsia in rats that were switched from the scheduled delivery of pellets to powder. Ethological analysis of the behavior showed that the rats receiving powder were not engaging excessively in some behavior other than drinking. After discounting several factors, we concluded that the amount of oral activity associated with feeding, which occurred immediately after food delivery, was reciprocally related to the level of drinking.     

A matching law analysis of the reinforcing efficacy of wheel running in rats

Previous research has demonstrated that running in a rotating wheel functions as a reinforcer for leverpressing in rats. In these studies, the pattern of responding was similar to the pattern of responding maintained by consummatory reinforcers, such as food and water. The present study investigated quantitative features of responding maintained by running. In previous experiments in which responses were reinforced according to variable-interval (VI) schedules and food and water served as the reinforcer, the equation for a rectangular hyperbola described the relationship between response rate and reinforcement rate. This experiment tested whether this quantitative regularity also applies to leverpressing maintained by the opportunity to run in a wheel. Fourteen male Wistar rats responded on levers for the opportunity to run. In each session, subjects were exposed to a series of VI schedules. An opportunity to run for 60 sec was the reinforcing consequence. Results showed that response rate was a negatively accelerated function of reinforcement rate, and the relationship between these two variables was described well by the equation for a rectangular hyperbola. To further test the similarity between running and consummatory reinforcers, the response requirement and access were manipulated. In previous experiments with food and water, these types of manipulations differentially changed the two parameters of the hyperbola. A similar pattern of results was obtained with wheel running. Thus, the equation appears to apply to running about as well as it does to consummatory reinforcers.     

The effects of variations in the interpellet interval on wheel running in the rat

Three rats were given access to a running wheel during spaced food deliveries. As the interpellet interval increased, the overall amount of running increased, the rate of running neither systematically increased nor decreased, and the locus of maximal running occurred later in the interpellet interval. Both the overall amount and the temporal distribution of running exhibited considerable within-schedule changes during successive exposures to the different schedules. These data are discussed in terms of Staddon’s (1977) assignment of behavior into different functional classes, that is, schedule-induced and facultative.     

Frequency,duration, and speed of wheel running of rats as a function of age and starvation

The purpose of this experiment was to determine whether age differences in amounts of wheel running of starved rats were due to the frequency of bursts of running, to the average duration of bursts, to speed, or to any combination of these parameters. The experiment was carried out according to a 3 by 2 by 2 mixed model design. The independent variables were age (67, 293, and 746 days old at the start of starvation), food deprivation (total starvation vs ad lib), and occasion of measurement (initial vs maximum activity). The dependent variables were number of wheel revolutions, number of bursts of activity, number of seconds of running per burst, and revolutions per second. The results indicated that acutely starved rats run more often, for longer periods, and at higher speeds than do sated rats, and that with increased age rats run less often, for a shorter time, and at slower speeds.     

Classroom Interactions: Constructing a Room with a View

An analysis of teacher-student interactions leads to critical reflections of the assumptions underlying the pedagogical choices this professor makes in undergraduate classes. Using concepts of perception of credibility and politics of recognition, the teacher gains insight into the equity of her practices.     

The interaction of conditioned taste aversions and schedule-induced polydipsia: Availability of alternative behaviors

Animals poisoned following exposure to saccharin subsequently avoided the schedule-induced consumption of saccharin. While this suppression was transient for subjects who had access only to the saccharin solution during the free-food presentations, recovery of schedule-induced saccharin consumption was significantly retarded for subjects who had concurrent access to saccharin and a running wheel. It has been suggested that the transient suppression of schedule-induced polydipsia by conditioned taste aversions results from the pellet-induced tendency to drink within the schedule-induced polydipsia procedure. That access to the running wheel reduces schedule-induced polydipsia in general and prolongs the suppression of schedule-induced polydipsia by taste aversions supports this view.     

Preschool Contexts and Teacher Interactions: Relations with School Readiness

The majority of early education programs promote children’s learning through a mix of experiences in child- and teacher-managed contexts. The current study examined time spent in child- and teacher-managed contexts and the nature of children’s experiences with teachers in these contexts as they relate to children’s skill development. Participants were preschool children (N = 283, M age = 52 months, 48% girls, 70% Mexican or Mexican American) from families of a lower socioeconomic status. Observations captured children’s time in child- and teacher-managed contexts and experiences with teachers in each context. School readiness was assessed directly and through teacher reports. Research Findings: Time spent in teacher-managed contexts was positively related to children’s academic and social skill development. Experiences in child-managed context predicted vocabulary, math, and social skills when teachers were directly involved with children. Overall, the findings suggest that teacher engagement is related to positive outcomes even during child-managed activities. Practice or Policy: Given these findings, preservice and professional development programs for early childhood educators should have a component that focuses on how to enhance the teacher’s role during child-managed activities.     

Interest enhancements to science experiments: Interactions with student gender

Males are more likely than females to aspire to and enter scientific careers, a pattern that might be attributed to gender differences in the appeal of school science. Differences might arise, in part, from gender-related interactions with the interest value of school science experiments. If modifiable, the interest value of experiments could influence attitudes toward science and subsequent choices concerning science involvement. In this study, middle school students carried out versions of science experiments designed to vary in their interest value. Experiment modifications, guided by a three-component model of interest, ranged from introduction of fantasy scenarios to manipulation of the difficulty and social context of the experiments. Subjects were 101 middle school students, 46 males and 55 females. Of primary interest were MANOVA comparisons of self-reported interest in the experiments, by gender and experimental condition. In general, interest enhancements were more effective for girls than boys. Boys were more attentive to aspects of the experiments that elicit perceptions of control, whereas girls were more attentive to social aspects.     

The interaction of conditioned taste aversions and schedule-induced polydipsia: Effects of repeated conditioning trials

In Experiment 1, rats poisoned following schedule-induced saccharin consumption showed a moderate reduction in the schedule-induced consumption of saccharin. With repeated poisoning, schedule-induced saccharin polydipsia was markedly reduced. Acquisition of conditioned aversion under the schedule-induced procedure was significantly slower than acquisition under water deprivation. In addition, recovery of consumption of the previously poisoned solution during extinction was more rapid under schedule-induced polydipsia. Experiment 2 revealed that schedule-induced polydipsia was less sensitive to suppression by conditioned aversions than a prandial drinking condition in which subjects were equally food deprived but were given a mass feeding instead of spaced pellet deliveries, suggesting that the relative insensitivity of schedule-induced polydipsia to conditioned taste aversions is not simply a function of different levels of food deprivation. This relative insensitivity is offered as a partial basis for the occurrence and maintenance of schedule-induced alcohol polydipsia.     

Splitting Clips and Telling Tales: Students Interactions with Digital Video

This paper reports on an experimental project in digital video editing with 10 year olds in the UK which explored their interactions with creative digital technologies. Data on the pupil’s interactions with the software was gathered on video and analysed. A theoretical framework drawn from second generation activity theory was applied and tensions resulting from mismatches between pupil’s approaches to the task and the ways the task were framed are reported on. The paper argues that pupils exhibit a number of behaviour based roles in relation to the technology dependent on compliance with the instructions of the teachers, creativity and their desire to explore the affordances of the technology. The paper concludes by asking questions about how new forms of cultural production such as digital video work can be incorporated authentically into school settings, and how a pedagogy to support learning with new types of technology can be developed by drawing on insights provided by socio-cultural approaches to understanding technology use in human activity systems.     

略论"依法治校"和"以德治校"

“依法治校”和“以德治校”存在着内在的、必然的联系,二者的结合是治校、治教理念的发展。我们要推进“依法治校”,以促进高校管理水平的提高;推进“以德治校”,以提高学校品位和人才培养质量。     

The insensitivity of schedule-induced polydipsia to conditioned taste aversions: Effect of amount consumed during conditioning

In Experiment 1, animals poisoned following schedule-induced or prandial-induced saccharin consumption subsequently showed identical aversions to saccharin when tested under water deprivation. In Experiment 2, animals conditioned to avoid saccharin to similar levels under water deprivation were differentially affected when saccharin was subsequently presented on the baselines of schedule-induced and prandial-induced drinking. Together, these data indicate that the differential effects observed on schedule-induced and prandial-induced drinking when animals are poisoned following consumption under these two schedules do not reflect the differential acquisition of taste aversions, but instead reflect the differential tendencies to drink induced by the spaced and massed feedings.     

高校举债办学的若干问题探索

本文分析高校举债办学的一些问题.在国家财力投入严重不足,而高等教育办学规模和招生人数急剧扩大,进入一个快速发展的时期.随着社会主义市场经济的不断发展,按照<中华人民共和国教育法>规定,高校作为独立法人单位,依法从多渠道筹集资金既是必要的,也是可行的.但在争取金融信贷等方面的支持以弥补资金不足的同时,高校必须密切关注财务风险,采取积极有效的措施进行风险防范和风险控制,做到既有效使用明天的钱办今天的事,为明天的发展打下坚实的基础,又能把财务风险控制在合理水平,实现高校的良性、非常规、跨跃式发展.     

对于轮和完全图的Ramsey函数的渐近上界

给出了当n趋向于无穷时, 对于不小于4的偶数m, 有r(Wm, Kn)≤(1 o(1))C1·(n)/(logn)(2m-2)/(m-2); 对于不小于5的奇数m, 有r(Wm, Kn)≤(1 o(1))C2(n(2m)/(m 1))/(logn)(m 1)/(m-1). 这里C1=C1(m)＞0, C2=C2(m)＞0. 特别地, C2(5)=12. 该定理是在Caro等给出的r(Cm, Kn)的渐近上界的基础上利用函数fm(x)=∫10((1-t)(1)/(m)dt)/(m (x-m)t) 得到的. 当n趋向于无穷时, c(n)/(logn)(5)/(2)≤r(K4, Kn)≤(1 o(1))(n3)/((logn)2). 本文还给出了r(Kk Cm, Kn)的渐近上界.     

A Model for Computer-based Assessment: The catherine wheel principle

The success of computer-based assessment systems is based on a structured approach to design and implementation together with a model that generates efficient and effective standards and procedures. This paper proposes a model that utilises a step-wise approach to assessment design and implementation within which the management and assessment of operational, technical, pedagogic and financial risks are made explicit. It is the strategies for risk elimination that form the basis for the standards and procedures adopted.