Neurons in monkey prefrontal cortex that track past or predict future performance

Although frontal cortex is thought to be important in controlling behavior across long periods of time, most studies of this area concentrate on neuronal responses instantaneously relevant to the current task. In order to investigate the relationship of frontal activity to behavior over longer time periods, we trained rhesus monkeys on a difficult oculomotor task. Their performance fluctuated during the day, and the activity of prefrontal neurons, even measured while the monkeys waited for the targets to appear at the beginning of each set of trials, correlated with performance in a probabilistic rather than a determinist manner: neurons reflected past or predicted future performance, much more than they reflected current performance. We suggest that this activity is related to processes such as arousal or motivation that set the tone for behavior rather than controlling it on a millisecond basis, and could result from ascending pathways that utilize slow, second-messenger synaptic processes.     

Observation Is Insufficient for Discovering that the Surface of Still Water Is Invariantly Horizontal

Among women college students who did not know that the surface of still water in a bottle is always horizontal, two types of specific task procedures designed to elicit self-discovery of the principle were ineffective. Failure to acquire the concept was reflected in inaccurate responses on the adjustment task and by inability of students to verbalize a correct strategy.     

Illusions in reasoning about consistency

Reasoners succumb to predictable illusions in evaluating whether sets of assertions are consistent. We report two studies of this computationally intractable task of "satisfiability." The results show that as the number of possibilities compatible with the assertions increases, the difficulty of the task increases, and that reasoners represent what is true according to assertions, not what is false. This procedure avoids overloading memory, but it yields illusions of consistency and of inconsistency. These illusions modify our picture of human rationality.     

Auditory evoked potentials during speech perception

Neural responses evoked by the same binaural speech signal were recorded from ten right-handed subjects during two auditory identification tasks. One task required analysis of acoustic parameters important for making a linguistic distinction, while the other task required analysis of an acoustic parameter which provides no linguistic information at the phoneme level. In the time interval between stimulus onset and the subjects' identification responses, evoked potentials from the two tasks were significantly different over the left hemisphere but identical over the right hemisphere. These results indicate that different neural events occur in the left hemisphere during analysis of linguistic versus nonlinguistic parameters of the same acoustic signal.     

展着剂提高毒死蜱对桑白蚧成虫防效的研究

蚧壳虫是一类难于防治的害虫,种类多、发生范围广,严重影响果树生产。蚧壳虫防治的难点在于若虫时期短,防治时期极易错过,而成虫雌蚧体外被有蜡质介壳,化学药剂不易穿透导致药效极低。为了提高化学药剂防治蚧壳虫的效果,进行了化学药剂筛选、展着剂筛选以及化学药剂与展着剂混合使用的筛选试验。结果表明：毒死蜱1 000倍液与展着剂甲基三氧乙基硅烷2 000倍液混合使用,对桑白蚧成虫防治效果最好,相对防效达81.21%。     

A graph-dynamic model of the power law of practice and the problem-solving fan-effect

Numerous human learning phenomena have been observed and captured by individual laws, but no unified theory of learning has succeeded in accounting for these observations. A theory and model are proposed that account for two of these phenomena: the power law of practice and the problem-solving fan-effect. The power law of practice states that the speed of performance of a task will improve as a power of the number of times that the task is performed. The power law resulting from two sorts of problem-solving changes, addition of operators to the problem-space graph and alterations in the decision procedure used to decide which operator to apply at a particular state, is empirically demonstrated. The model provides an analytic account for both of these sources of the power law. The model also predicts a problem-solving fan-effect, slowdown during practice caused by an increase in the difficulty of making useful decisions between possible paths, which is also found empirically.     

新农村建设中村级财务管理存在的问题及其对策

农村村级财务管理问题是广大农民群众普遍关心的热点问题,也是“三农”工作的重点和难点问题。农村村级财务管理中存在的会计核算不规范、资产管理混乱、财会人员素质不高、监管体系不完善等问题,应当从多个方面入手改善。     

Cerebellum activation associated with performance change but not motor learning

The issue of whether the cerebellum contributes to motor skill learning is controversial, principally because of the difficulty of separating the effects of motor learning from changes in performance. We performed a functional magnetic resonance imaging investigation during an implicit, motor sequence-learning task that was designed to separate these two processes. During the sequence-encoding phase, human participants performed a concurrent distractor task that served to suppress the performance changes associated with learning. Upon removal of the distractor, participants showed evidence of having learned. No cerebellar activation was associated with the learning phase, despite extensive involvement of other cortical and subcortical regions. There was, however, significant cerebellar activation during the expression of learning; thus, the cerebellum does not contribute to learning of the motor skill itself but is engaged primarily in the modification of performance.     

论“全概公式”与“逆概公式”的教学

本文对“全概公式”与“逆概公式”进行了剖析,并指出运用这两个公式的关键是要善于找出一个合适的完备事件组.最后举了几个较困难但很有趣的问题。由于随用了“全概公式”及“逆概公式”而使解题的思路清晰,从而降低了题目的难度.     

Pupil diameter and load on memory

During a short-term memory task, pupil diameter is a measure of the amount of material which is under active processing at any time. The pupil dilates as the material is presented and constricts during report. The rate of change of these functions is related to task difficulty.     

Operant control of eye movements during human vigilance

Eye movements were used as a criterion of observing responses in a vigilance task. Time on watch and signal rates similarly affected both eye-movement rates and percentage of detections. Observing rate may account for detection data, and may be a more stable measure of vigilance than detection rate is, especially when very few signals occur.     

乡镇村级防疫员发展状况的调查与建议

乡镇村级动物防疫员处于动物疫病防控的第一线,是最基层的防疫队伍,是农村实施动物强制免疫、疫情测报的主体力量。村级防疫员在业务主管部门的领导下做了大量艰苦工作,取得明显成绩。当前动物疫病日趋复杂,危害性突出,防控任务更加艰巨。沿袭以往春秋两季及突击式的防疫方式,已难以有效防控重大动物疫病的发生。建立一支相对稳定的、与防疫任务相适应的村级防疫员队伍,常年做好以小规模和散养户为主要服务对象的村级动物防疫工作,已迫在眉睫。经对乡镇村级防疫员发展状况进行调查,在农村局部区域内的兽医防疫工作尚存在一定问题,亟待研究解决。     

性别刻板印象对注意定向和解脱的影响

采用注意线索任务分析了性别刻板印象对注意定向和解脱的影响,发现有效提示条件下刻板印象的激活可以加快被试的注意定向,使注意迅速指向与性别刻板印象一致的女性信息,但无效提示条件下,以上注意促进效应消失;对解脱量的进一步分析显示,在刻板不一致条件下,个体对于男性的解脱量显著高于对于女性的解脱量,表现出对于男性刻板不一致信息的解脱困难.结果表明:性别刻板印象对于注意的定向和解脱过程存在显著影响,并呈现出一种不同注意阶段、不同性别加工差异的特点.     

我国国有企业MBO过程中的融资问题探讨

融资困难是制约我国国有企业实施管理层收购(MBO)的主要障碍之一。如何缓解融资困境是管理层必须面对的问题。本文根据我国目前金融制度及融资环境的特点,提出具有中国特色的“三步”MBO融资法,该方法可以有效缓解我国国有企业MBO的融资困境。     

机会收益——水权转换中一个值得关注的理论和实践问题

黄河河套灌区目前亟待解决的难题是：虽认同农民用水者协会（Water Users Association，WUA）是不可或缺的节水组织载体，但又对WUA管理经费困难、难以为继苦无良策．农民有强烈反响的因节水而节约的支出难抵水价上涨成为严峻事实，这种状况有悖于水权转换的初衷，也导致WUA的收费尴尬．现有的水权转换政策规定，新上工业项目无取水指标，必须从农业节水中等量置换．当前宁夏水的转换费用涨到7元／m^3，已是灌溉水价的200多倍，由此造成巨大的“机会收益”．国内外研究侧重于水权明晰和参与式管理，对因工农业用水转换而产生的“机会收益”鲜有涉及，本研究就水权转换的现实问题提出探讨，以期引起广泛关注与深入研究．     

不可传释的传释——以《加油站》为例，浅析英诗汉译中的“准确性”问题

诗歌翻译是难度极大的一项工作，要想把一首英文诗歌的“说什么”和“如何说”完整传释出来，几乎是一件不可能的事情。伊丽莎白·毕晓普《加油站》一诗的汉语翻译，即说明保证诗歌翻译准确的不易，以及达到诗歌翻译准确的重要。     

Learned predictions of error likelihood in the anterior cingulate cortex

The anterior cingulate cortex (ACC) and the related medial wall play a critical role in recruiting cognitive control. Although ACC exhibits selective error and conflict responses, it has been unclear how these develop and become context-specific. With use of a modified stop-signal task, we show from integrated computational neural modeling and neuroimaging studies that ACC learns to predict error likelihood in a given context, even for trials in which there is no error or response conflict. These results support a more general error-likelihood theory of ACC function based on reinforcement learning, of which conflict and error detection are special cases.     

我国农业保险面临的困境及发展研究

厘清了农业保险的内涵,从我国农业保险发展面临的困境出发,用经济学原理和博弈论方法分析了导致农业保险发展困难的原因,并对我国农业保险如何走出困境、恢复活力提出了相关对策建议。     

相似距离分析法在卷烟感官评价分析中的应用

为研究卷烟的感官评价,将相似距离计算方法运用到卷烟感官及香气特征比较分析中,计算两组变量间的亲疏程度,并将其具体应用到卷烟香气风格综合定量分析中,成功解决了传统雷达图对不同品牌卷烟之间、同品牌卷烟不同批次之间品质特征难以进行比较的问题,对新产品开发、老产品的优化提质、卷烟品质稳定性控制、产品异地加工的质量稳定性评价具有...     

安徽省水土保持现状评价与需求分析

结合安徽省水土流失现状,在对水土保持现状面临的形势、挑战和发展机遇分析评价的基础上,对该省水土保持的需求进行了分析和探讨。鉴于水土保持综合防治任务的长期性、反复性和艰巨性,提出了今后一段时期水土流失综合防治的主要任务。