神经网络对φ-有界变差函数的逼近

研究了以有界的sigmoidal函数σ为激活函数的单隐层神经网络对于在[a,b]上φ-有界变差函数f的逼近,得到的逼近偏差为‖σ‖φ-1{Vφ(fn)[a,b]/n}.倘若激活函数是Heaviside函数时,则逼近偏差为φ-1{Vφ(f)[a,b]/2n}.此外,在第3节中,我们还将上述结果扩充到了全实轴上.     

基于不完备频响函数辨识结合部等效参数的研究

研究了输出信息不完备情况下结合部等效动力学参数的辨识问题,阐述了一种较为通用的结合部等效动力学参数辨识方法.首先采用实验与有限元法相结合,辨识出试验中难以获取的频响函数,构造出完备频响函数.然后通过完备频响函数,运用迭代算法辨识出结合部等效动力学参数.在辨识过程中,建立损失函数模型,将问题转化为求解损失函数的最小值问题.该方法不需要求出模态参数,所以同样适用于大阻尼系统或者模态密集系统的结合部参数辨识.由于只需部分易测的频响函数,所以具有很好的工程应用性.最后通过算例验证了本方法具有很高的辨识精度.     

表面态对碳纳米管场发射的影响

采用CVD法在Ni丝上直接沉积碳纳米管,并应用二极管结构测试表面态(突出尖端和吸附)对碳纳米管场发射的影响。测试表明,突出尖端主要影响碳纳米管场发射的开启电场以及场发射电流稳定性;吸附作用的影响表现在改变碳纳米管能带结构进而改变其场发射性能。     

Fortran 90模拟C++函数重载

函数重载是C++语言多态性的重要体现,也是面向对象程序设计的常用方法,Fortran 90不支持面向对象程序设计,但已经具有一些现代语言特征,为模拟面向对象程序设计提供可能,在分析C++函数重载机制的基础上,通过对Fortran 90相关语言元素、工具的探索,提出利用Fortran 90新增加的接口块这一利器模拟C++函数重载的方法,实例运行结果表明,该方法现实可行,从而扩展Fortran 90的应用范围,并为模拟面向对象程序设计提供思路。     

Examining functional content in widely used Health-Related Quality of Life scales.

Purpose: Assess extent to which generic Quality of Life (QOL) and Health-Related Quality of Life (HRQOL) scales include function in assessment of health, and identify health assessment items that are free of functional content. Methods: An expert panel on measurement of health and disability reached consensus on definitions of health, disability, and function. They assessed all items of all generic (non-condition-specific) scales in the 2006 ProQolid database for being important to measuring health as distinct from function. Ratings were summarized as content validity ratios. Retained items were written into standard format and reviewed again by the expert panel and a validity panel with expertise in specific disabilities. Results: Of 85 scales, 21 were retained as containing items important for assessing health. Scales ranged from 100% (BRFSS HRQOL, WHO-5) to only 4% of items rated as important. In further review of “important” items, functional content was identified in many of the items, particularly with regard to mental functioning. Conclusions: Popular generic scales of QOL and HRQOL vary greatly in the degree to which they include content on function. A pool of items can be identified that are relatively free of function. Distinguishing measurement of function and health is particularly important for people with long-standing functional limitations and for assessing the relationship of health with function. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Alcohol intake and cognitive abilities in old age: The Lothian Birth Cohort 1936 study.

Objective: Moderate alcohol consumption has been associated with better cognitive performance in late adulthood, possibly by improving vascular health. Few studies have examined the potentially confounding roles of prior cognitive ability and social class in this relationship. Method: Participants were 922 healthy adults about 70 years old in the Lothian Birth Cohort 1936 study, for whom there are IQ data from age 11. Alcohol consumption was obtained by self-report questionnaire. Cognitive outcome measures included general cognitive ability, speed of information processing, memory, and verbal ability. Results: Moderate to substantial drinking (>2 units/day) was associated with better performance on cognitive tests than low-level drinking (≤2 units/day) or nondrinking in men and women. After adjusting for childhood IQ and adult social class, most of these associations were removed or substantially attenuated. After full adjustment, a small, positive association remained between overall alcohol intake and memory (women and men) and verbal ability (women only). Women's overall alcohol intake was derived almost exclusively from wine. In men, effects differed according to beverage type: wine and sherry–port consumption was associated with better verbal ability, but beer was associated with a poorer verbal ability and spirits intake was associated with better memory. Conclusions: Prior intelligence and socioeconomic status influence both amount and type of alcohol intake and may partly explain the link between alcohol intake and improved cognitive performance at age 70. Alcohol consumption was found to make a small, independent contribution to memory performance and verbal ability, but these findings' clinical significance is uncertain. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Chronological age and age-related cognitive deficits are associated with an increase in multiple types of driving errors in late life.

Objective: Older driver research has mostly focused on identifying that small proportion of older drivers who are unsafe. Little is known about how normal cognitive changes in aging affect driving in the wider population of adults who drive regularly. We evaluated the association of cognitive function and age with driving errors. Method: A sample of 266 drivers aged 70 to 88 years were assessed on abilities that decline in normal aging (visual attention, processing speed, inhibition, reaction time, task switching) and the UFOV?, which is a validated screening instrument for older drivers. Participants completed an on-road driving test. Generalized linear models were used to estimate the associations of cognitive factors with specific driving errors and number of errors in self-directed and instructor navigated conditions. Results: All error types increased with chronological age. Reaction time was not associated with driving errors in multivariate analyses. A cognitive factor measuring speeded selective attention and switching was uniquely associated with the most errors types. The UFOV? predicted blind-spot errors and errors on dual carriageways. After adjusting for age, education, and gender, the cognitive factors explained 7% of variance in the total number of errors in the instructor-navigated condition and 4% of variance in the self-navigated condition. Conclusion: We conclude that among older drivers, errors increase with age and are associated with speeded selective attention, particularly when that requires attending to the stimuli in the periphery of the visual field, task switching, errors inhibiting responses, and visual discrimination. These abilities should be the target of cognitive training. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Teaching posttraining: Influencing diagnostic strategy with instructions at test.

It is believed that medical diagnosis involves two complementary processes, analytic and similarity-based. There is considerable debate as to which of these processes defines diagnostic expertise and how best to teach clinical diagnosis and reduce diagnostic errors. The purpose of these studies is to document the use of these strategies in medical students. We shifted the balance in use of these processes and improved diagnostic accuracy with instructions given posttraining at the moment of diagnosis. Analytic processing reflecting the degree to which cases contain the diagnostic rules was indexed by the rate of accuracy on typical versus atypical cases (typicality effect). Similarity-based processing reflecting the degree to which cases resemble previously encountered cases was indexed by the rate of accuracy on similar versus dissimilar cases (similarity effect). Two studies are presented illustrating that diagnosis involves the coordination of analytic and similarity-based processes and that differential instruction given at test shifts the balance in the use of these processes. Study 1 illustrated that participants adopting an analytic strategy exhibit a larger effect of typicality. Participants adopting a similarity-based strategy exhibit a larger effect of similarity. The diagnostic approach of students given no instructions was predominantly analytic. Dual instructions in which participants first employed similarity-based processing followed by the application of rules improved overall accuracy. Study 2 investigated two versions of dual instructions and illustrated that assessing a case with the rules of diagnosis first may inhibit the subsequent use of similarity-based reasoning. The implications for diagnostic expertise and pedagogy are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A communication-based intervention for nonverbal children with autism: What changes? Who benefits?

Objective: This article examines the form and function of spontaneous communication and outcome predictors in nonverbal children with autism following classroom-based intervention (Picture Exchange Communication System [PECS] training). Method: 84 children from 15 schools participated in a randomized controlled trial (RCT) of PECS (P. Howlin, R. K. Gordon, G. Pasco, A. Wade, & T. Charman, 2007). They were aged 4–10 years (73 boys). Primary outcome measure was naturalistic observation of communication in the classroom. Multilevel Poisson regression was used to test for intervention effects and outcome predictors. Results: Spontaneous communication using picture cards, speech, or both increased significantly following training (rate ratio [RR] =1.90, 95% CI [1.46, 2.48], p     

发挥高校资助工作育人功能的路径探索

当前,我国已经形成了以国家、学校资助为主体,社会资助为辅助的较为完善的高校学生资助体系,有力地促进了教育公平和教育事业健康发展。如何充分发挥资助工作的育人功能,构建发挥高校资助工作育人功能的路径,对于高等教育的可持续发展具有重大而深远的意义。文章以国家奖助学金为例,分析了资助工作中蕴含的育人功能,并具体探讨了构建发挥高校资助工作育人功能的路径。