Statistical properties of nucleotide clusters in DNA sequences

Using the complete genome of Plasmodiumfalciparum 3D7 which has 14 chromosomes as an example, we have examined the distribution functions for the amount of C or G and A or T consecutively and non-overlapping blocks of m bases in this system. The function P(S) about the number of the consecutive C-G or A-T content cluster conforms to the relation P(S)oce-as;values of the scaling exponent αCG are much larger than αAT; and αAT of 14 chromosomes are hardly changed, whereas αCG of 14chromosomes have a number of fluctuations. We found maximum value of A-T cluster size is much larger than C-G, which implies the existence of large A-T cluster. Our study of the width function ξ(m) of cluster C-G content showed that follows good power law ξ(m)ocm-γ. The average γ for 14 chromosomes is 0.931. These investigations provide some insight into the nucleotide clusters of DNA sequences, and help us understand other properties of DNA sequences.     

基于TOP224Y的高性能AC/DC电源设计

介绍了一种具有多路输出的单端反激式开关电源的设计方法,给出了基于智能控制集成芯片TOP224Y的电源设计电路,并对外围输入整流滤波电路、高频变压器、输出整流滤波电路、反馈电路、保护电路五个部分的设计进行了分析和说明。此电源具有成本低、效率高、尺寸小、可靠性高等特点。     

Effects of feedback timing and motivational content on teachers' delivery of contingent social praise

This study examined the relative effects of feedback timing (delayed or immediate) and motivational content (goal-setting) on teachers' delivery of contingent social praise for on-task behavior. Two teachers of behaviorally disordered children and two youngsters from each class served as subjects. The study employed an adaptation of a single subject replication design. Teachers were exposed to four experimental conditions: baseline (no feedback), immediate feedback, delayed feedback, and delayed feedback plus goal-setting. These conditions were replicated either within or across teacher subjects. The results showed that all feedback tactics produced an increase in contingent social praise and student on-task behavior over baseline levels. However, the only statistically significant increases occurred when teachers were exposed to the delayed feedback plus goal-setting procedure.     

父母消极控制与反馈对青少年社会适应的影响:黑暗人格与同伴关系的链式中介作用

为探究父母消极控制与反馈、黑暗人格、同伴关系、社会适应的关系以及其内部作用机制,对1934名中学生采用整群施测法进行问卷调查.结果 发现:1.父母消极控制与反馈、黑暗人格和积极社会适应呈显著负相关,和消极社会适应呈显著正相关;同伴关系和积极社会适应呈显著正相关,和消极社会适应呈显著负相关.2.控制了家庭社会经济地位的影...     

A State-Wide School-Building Survey

ABSTRACT

The authors intended to (a) identify the association between gender or grade level and teachers’ homework (HW) feedback and (b) examine the relationship between teachers’ HW feedback, HW-related behaviors (e.g., amount of HW completed), and academic achievement. Four hundred fifty-four students (Grades 5–12) participated in this study. The results showed that (a) at higher grade levels, there is a lower perceived amount of teachers’ HW feedback; (b) teachers’ HW feedback as perceived by students is positively and significantly related to the amount of HW completed and to the perceived quality of HW time management but not to the amount of time spent on HW; (c) the amount of HW completed and the perceived quality of HW time management positively and significantly predict academic achievement; and (d) teachers’ HW feedback as perceived by students has an indirect relationship with students’ academic achievement by its effect on students’ HW-related behaviors.     

A new algorithm based on metaheuristics for data clustering

This paper presents a new algorithm for clustering a large amount of data.We improved the ant colony clustering algorithm that uses an ant’s swarm intelligence,and tried to overcome the weakness of the classical cluster analysis methods.In our proposed algorithm,improvements in the efficiency of an agent operation were achieved,and a new function "cluster condensation" was added.Our proposed algorithm is a processing method by which a cluster size is reduced by uniting similar objects and incorporating them into the cluster condensation.Compared with classical cluster analysis methods,the number of steps required to complete the clustering can be suppressed to 1% or less by performing this procedure,and the dispersion of the result can also be reduced.Moreover,our clustering algorithm has the advantage of being possible even in a small-field cluster condensation.In addition,the number of objects that exist in the field decreases because the cluster condenses;therefore,it becomes possible to add an object to a space that has become empty.In other words,first,the majority of data is put on standby.They are then clustered,gradually adding parts of the standby data to the clustering data.The method can be adopted for a large amount of data.Numerical experiments confirmed that our proposed algorithm can theoretically applied to an unrestricted volume of data.     

The Power of the Test for Treatment Effects in Three-Level Cluster Randomized Designs

Abstract

Experiments that involve nested structures often assign entire groups (such as schools) to treatment conditions. Key aspects of the design of such experiments include knowledge of the intraclass correlation structure and the sample sizes necessary to achieve adequate power to detect the treatment effect. This study provides methods for computing power in three-level cluster randomized balanced designs (with two levels of nesting), where, for example, students are nested within classrooms and classrooms are nested within schools and schools are assigned to treatments. The power computations take into account nesting effects at the second (classroom) and at the third (school) level, sample size effects (e.g., number of schools, classrooms, and individuals), and covariate effects (e.g., pretreatment measures). The methods are applicable to quasi-experimental studies that examine group differences in an outcome.     

基于Simulink的外光反馈半导体激光器动态特性的模拟研究

文章提出了一种新的研究外光反馈半导体激光器动力学行为的方法,利用Simulink仿真软件建立可视化模型模拟了弱反馈至中等反馈下外光反馈半导体激光器的动态特性,结果表明弱反馈下系统处于周期态,增加反馈量系统的输出由周期态进入混沌态.并对用高频电流注入(HFI)技术控制外光反馈半导体激光器的混沌进行了模拟研究.与基于常规高级程序设计语言的计算机模拟技术相比,该方法避免了传统意义上的复杂算法编程和调试过程,可以方便的改变模型参数并观察到相应的模拟结果.     

Power Analyses for Moderator Effects in Three-Level Cluster Randomized Trials

Researchers are often interested in whether the effects of an intervention differ conditional on individual- or group-moderator variables such as children's characteristics (e.g., gender), teacher's background (e.g., years of teaching), and school's characteristics (e.g., urbanity); that is, the researchers seek to examine for whom and under what circumstances an intervention works. Furthermore, the researchers are interested in understanding and interpreting variability in treatment effects through moderation analysis as an approach to exploring the sources of the treatment effect variability. This study develops formulas for power analyses to detect the moderator effects in designing three-level cluster randomized trials (CRTs). We develop the statistical formulas for calculating statistical power, minimum detectable effect size difference, and 95% confidence intervals for cluster or cross-level moderation, nonrandomly varying or random slopes, binary or continuous moderators, and designs with or without covariates. We demonstrate how the calculations can be used in the planning phase of three-level CRTs using the software PowerUp!-Moderator.     

Frequency-feedback based islanding detection algorithm for micro-grid

The unintentional islanding of micro-grid may cause negative impacts on distribution loads and distributed generations, so it must be detected within the acceptable duration. In this paper a new islanding detection algorithm is proposed. This algorithm introduces the frequency feedback method by the reactive power compensation to derive the frequency continuous shift. Accordingly, the islanding can be detected by monitoring the frequency within 0.1 s. The simulationresults prove that this algorithm has extremely small non-detection zone, and meanwhile it presents an excellent islanding detection speed as well.     

追加反馈对背越式跳高学习效果影响的实验研究

采用实验法,探讨不同频率的追加反馈对运动技能学习效果的影响。结果显示,在运动技能的学习过程中,给予学习者追加反馈有助于学习效果的提高。但是过高频率的追加反馈会减少学习者自身的内部反馈,给运动技能学习效果带来负效应。只有建立一个科学、合理的反馈频率区间值,明确最佳指导运动技能学习的追加反馈频率,才能使运动技能的学习得到最优化控制。     

When peers agree,do students listen? The central role of feedback quality and feedback frequency in determining uptake of feedback

Prior research on the complex process of revision based upon peer feedback has focused on characteristics of each piece of feedback in isolation. Multipeer feedback allows for feedback to be repeated (or not), which could be a signal of feedback quality or be especially persuasive to peers. Separately, little research has examined how well peers select more impactful and accurate peer feedback in their revisions, whether repeated or not. We analyzed almost 2,000 peer comments received by 107 students in a secondary writing course in the US to determine whether feedback quality and feedback frequency predicted feedback implementation. Controlling for other feedback features and context factors, students were much more likely to implement feedback as both feedback quality and feedback frequency increased, surprisingly with no interaction (i.e., even low-quality comments were more likely to be implemented when repeated). However, low-quality comments often partially overlapped with high-quality comments, providing a potential explanation for the lack of an interaction. Finally, consideration of feedback frequency and feedback quality provides new insights into which feedback features are actually related to implementation. The results generally allay concerns about the blind-leading-the-blind in peer feedback as well as pushing for peer feedback arrangements that produce more overlapping comments.     

Multi-mode controller IC for soft-switched flyback converter with high efficiency over the entire load range

This paper presents a multi-mode control scheme for a soft-switched flyback converter to achieve high efficiency and excellent load regulation over the entire load range. At heavy load, critical conduction mode with valley switching （CCMVS） is employed to realize soft switching so as to reduce turn-on loss of power switch as well as conducted electromagnetic interference （EMI）. At light load, the converter operates in discontinuous conduction mode （DCM） with valley switching and adaptive off-time control （AOT） to limit the switching frequency range and maintain load regulation. At extremely light load or in standby mode, burst mode operation is adopted to provide low power consumption through reducing both switching frequency and static power dissipation of the controller. The multi-mode control is implemented by an oscillator whose pulse duration is adjusted by output feedback. An accurate valley switching control circuit guarantees the minimum turn-on voltage drop of power switch. The prototype of the controller IC was fabricated in a 1.5-μm BiCMOS process and applied to a 310 V/20 V, 90 W flyback DC/DC converter circuitry. Experimental results showed that all expected functions were realized successfully. The flyback converter achieved a high efficiency of over 80% from full load down to 2.5 W, with the maximum reaching 88.8%, while the total power consumption in standby mode was about 300 mW.     

Use of Instructional Feedback and Modification Methods among University Faculty

This study focused on methods used by faculty to gather feedback and how this feedback was used to modify instruction. Data were gathered to determine the degree to which these methods of feedback and modification of instruction were dependent upon variables such as class size, teaching experience, pedagogical training, academic rank and status, gender and academic discipline. It was found that the amount of feedback and modification of instruction did not vary significantly across the variables of teaching experience and class size. The analyses examining the effects of the remaining independent variables (i.e. college of study, pedagogical training, gender, rank, status) did detect statistically significant results. Specifically, those instructors who had received some training in pedagogical methods gathered feedback about their teaching more than those instructors without such pedagogical training. Also, faculty from the Colleges of Education and Liberal Arts used more methods to gather feedback than those faculty from the College of Science and Mathematics. Faculty in the College of Science and Math also did the least in terms of course and instructional modification, significantly less than faculty in the Colleges of Agriculture, Business, Education, Engineering and Liberal Arts.     

A Framework for Measuring the Amount of Adaptation of Rasch‐based Computerized Adaptive Tests

A key consideration when giving any computerized adaptive test (CAT) is how much adaptation is present when the test is used in practice. This study introduces a new framework to measure the amount of adaptation of Rasch‐based CATs based on looking at the differences between the selected item locations (Rasch item difficulty parameters) of the administered items and target item locations determined from provisional ability estimates at the start of each item. Several new indices based on this framework are introduced and compared to previously suggested measures of adaptation using simulated and real test data. Results from the simulation indicate that some previously suggested indices are not as sensitive to changes in item pool size and the use of constraints as the new indices and may not work as well under different item selection rules. The simulation study and real data example also illustrate the utility of using the new indices to measure adaptation at both a group and individual level. Discussion is provided on how one may use several of the indices to measure adaptation of Rasch‐based CATs in practice.     

McWiLL集群系统网关的设计与实现

McWiLL集群系统网关是一种能实现使用不同集群通信方式的用户群之间的互通的网关。它采用双CPU结构,通过地隔离技术与屏蔽技术解决各种功率设备与射频设备对语音信号的强烈干扰问题;同时还采用智能识别方法解决双工设备与半双工设备间的语音交换过程中的VOX问题和自回环问题。实际使用表明Mcwill集群通信网关结构可行,设计技术合理。     

Investigating learners’ use and understanding of peer and teacher feedback on writing: A comparative study in a Chinese English writing classroom

Existing comparative studies between peer and teacher feedback in English writing classes have predominantly used frequency measures of peer and teacher feedback in learners’ revisions to suggest their relative values for developing learners’ writing proficiency. However, learners do not necessarily understand the feedback that is used in their redrafts.This study distinguished learners’ use from their understanding of peer and teacher feedback. Eighteen Chinese university English learners participated in the study for sixteen weeks. Three research methods were adopted: (a) content analyses of learners’ use of feedback, (b) stimulated recall interviews on learners’ understanding of feedback, and (c) interviews on the factors that affected learners’ responses to feedback.The findings suggested that the learners used more teacher than peer feedback in their redrafts. However, interviews with these learners revealed that they used a larger percentage of teacher feedback than peer feedback without understanding its significance or value. Student interviews uncovered learners’ passive acceptance of teacher feedback and the facilitative role of first language use in peer interaction.This study suggests that learners’ understanding of feedback should be taken as at least an equally important factor as learners’ use of feedback in examining the relative value of peer and teacher feedback for developing learners’ writing proficiency.     

Formative peer assessment in primary school: the effects of involving pupils in setting assessment criteria on their appraisal and feedback style

This experimental study is aimed at examining the effect of involving pupils in primary education in setting assessment criteria and standards on their appraisal of a peer’s work and their peer feedback style. It is expected that our intervention will lead to (1) a criteria-referenced appraisal and (2) more final vocabulary, which is associated with a more authoritative style. In total, 95 sixth grade pupils from The Netherlands were randomly assigned to one of two conditions. In the experimental group, the pupils first received an exemplar, which was followed by a group discussion about appropriate assessment criteria and standards. In the control group, the pupils provided peer feedback without this discussion. Their peer appraisal was measured with a questionnaire and feedback style was determined by analysing the written feedback using a person-oriented approach (cluster analysis). Results showed that the chance that pupils in the experimental group had an authoritative style was three times higher than in the control group. Theoretical and practical implications of the study are discussed.     

‘To be informed’: understanding the role of feedback information for Flemish/European policy

The aim of this article is to argue that the evident exchange of information on performance (and its supply, demand and use) should be regarded as a symptom of a new governmental regime that installs less evident power relations. Educational policy in Flanders (Belgium), and in particular the need for feedback information from the Flemish government, will be used as a case to describe this regime. Based upon the analytical framework of ‘governmentality’ (Foucault), the article focuses on the ‘governmentalization’ of Europe and Flanders that accompanies the need for feedback information. The main result of the analysis of European and Flemish policy documents can be summarized as follows: government or the ‘conduct of conduct’ currently takes the form of ‘feedback on performance’. This means that the strategy of the governmental regime is to secure an optimal performance for each and all (member states, schools), and acts upon the ‘need for feedback’ and ‘will to learn’ of the actors involved. On the basis of these findings, the article introduces in conclusion the notion ‘synopticon’ in order to grasp the exercise of power in ‘feedback on performance’.     

一种新型实用高频中小功率CO2激光电源

介绍一种新型实用CO2激光电源，利用IGBT为主开关管，采用高压包串联供电和预充电，在电路结构上更趋于小型化、高频化、集成化、通用化．测试和应用结果表明该电源具有良好的性价比和可靠性，达到雕刻印刷的高频开关要求，适于生产．