新疆区域农业品牌价值最大化及其评价指标与模型

基于对区域农业品牌和新疆区域农业品牌发展的研究综述,应用产品整体概念理论探讨了新疆农产品多层面产品要素的品牌化和综合品牌价值最大化,分析了支撑新疆农产品品牌价值最大化的产业链管理与创新,构建了新疆农业品牌价值最大化评价指标体系,并请新疆的11位农业专家进行评分,应用AHP方法得到了各指标的权重,构建了定量评价模型,以库尔勒香梨为案例,应用模糊综合评价方法测度了特定农产品品种的区域品牌价值,明确了新疆区域农业品牌发展面临的薄弱环节,为新疆政府和企业的品牌农业决策提供了理论依据.     

Investigating Essential Characteristics of Scientific Practices in Elementary Science Learning Environments: The Practices of Science Observation Protocol (P‐SOP)

Within the field of science education, there remains little agreement as to the definition and characteristics of classroom inquiry. The emerging emphasis on scientific practices in science education reform discourse is underpinned by a need to better articulate the constituent elements of inquiry‐based science. While a small number of observation‐based instruments have been developed to characterize science learning environments, few are explicitly aligned with theoretical constructs articulated by the National Research Council and/or have been substantially field‐tested. We employ a newly developed instrument, the Practices of Science Observation Protocol (P‐SOP), to investigate essential features of inquiry and scientific practices in which early learners engage in elementary classrooms. This research is part of a multiyear professional development program designed to support elementary teachers (K‐5) in a large, urban school district to learn to better engage students in scientific practices. Project teachers video‐recorded enacted science lessons (n = 124) which were used as data. Findings illustrate both essential features of inquiry and scientific practices observed in elementary classrooms, as well as establish the P‐SOP as a valid and reliable observation protocol. These findings have important implications for the design of elementary science learning environments and associated research and development efforts in the field.     

Transferring specialized content knowledge to elementary classrooms: preservice teachers’ learning to teach the associative property

This study explores how preservice teachers (PSTs) transfer the intended specialized content knowledge (SCK) to elementary classrooms. Focusing on the case of the associative property of multiplication, we compared three PSTs’ SCK during enacted lessons in fourth grade classrooms with their own learning in professional development (PD) settings. Findings revealed the PSTs’ successes and challenges in unpacking an example task, especially in areas of making connections between concrete and abstract representations and asking deep questions that target quantitative interactions. Factors that may have supported or hindered PSTs’ SCK transfer include the complex nature of teacher knowledge, the PD effort and the outside factors such as the support from textbooks and cooperating teachers. Implications for teacher education and directions for future research are discussed.     

Examining the Types,Features, and Use of Instructional Materials in Afterschool Science

Afterschool programs have garnered much attention as promising environments for learning where children can engage in rich science activities. Yet, little is known about the kinds of instructional materials used in typical, large‐scale afterschool programs that implement science with diverse populations of children. In this study, we investigated the types, features, and use of science instructional materials at more than 150 public afterschool program sites across California. Using afterschool site survey data, we categorized the types and the range of materials used at the sites. We then collected a subsample of the instructional materials for in‐depth analysis of their support features for enabling staff and children to enact science. We also interviewed afterschool site staff to better understand how they selected and used materials. Results from our analysis of survey and interview data show that afterschool staff primarily used stand‐alone lessons and activities found on the Internet or in activity books as resources for planning and enacting science. Our analysis of the subsample of instructional materials indicate that curricular materials, while used less frequently by afterschool staff, have on average more of the support features that would help them implement high‐quality science experiences with children.     

破坏性测量系统波动源的分析

测量系统分析是质量改进活动中的一个重要问题,评价测量系统精确度的标准方法是量具的重复性和再现性(R&R)研究,这种研究通常采用试验设计方法,而且对测量对象可以重复测量。然而在工业实践中,当遇到破坏性测量时,这种标准的R&R研究方法是无法实施的。本文给出了破坏性测量中测量系统波动源分析的一种方法,首先分析了破坏性测量中进行量具R&R研究的前提条件,进而给出了进行量具R&R研究的随机效应模型和方差分析方法;最后通过应用Minit-ab.14软件,对工业实践中的一个应用实例进行了分析。     

Characterizing STEM Teacher Education: Affordances and Constraints of Explicit STEM Preparation for Elementary Teachers

Although science, technology, engineering, and mathematics (STEM) education sits at the center of a national conversation, comparatively little attention has been given to growing need for STEM teacher preparation, particularly at the elementary level. This study analyzes the outcomes of a novel, preservice STEM teacher education model. Building on both general and STEM‐specific teacher preparation principles, this program combined two traditional mathematics and science methods courses into one STEM block. Analysis compared preservice teachers in the traditional courses with those enrolled in the STEM block, investigating STEM teaching efficacy, reported and exhibited pedagogical practices, and STEM literacies using a pre‐post survey as well as analysis of lesson planning products. Linear regression models indicated that substantial growth was seen in both approaches but STEM block preservice teachers reported significantly greater gains in STEM teaching efficacy as compared with traditional‐route teachers. Lesson planning artifacts also demonstrated increased facilitation of STEM literacies, with specific attention to content integration, engineering and design, and arts inclusion. Technology and computational thinking emerged as areas for further growth and clarification in STEM teacher education models. Findings contribute to a growing research base on developing the STEM teacher workforce.     

Finding Alignment: The Perceptions and Integration of the Next Generation Science Standards Practices by Elementary Teachers

Preparing elementary‐level teachers to teach in alignment with the eight Next Generation Science Standards (NGSS) practices could prove to be a daunting endeavor. However, the process may be catalyzed by leveraging elements of teacher science instruction that inherently attend to the practice standards. In this study, we investigated the science instruction of three grade 3–5 elementary‐level teachers. We used observation, interviews, and surveys to determine the level to which the teachers perceived they taught and engaged in teaching science aligned with the eight NGSS practices. We found that the teachers were partially, and intrinsically implementing several of these practices in their instruction, and at the same time could not articulate the eight NGSS practices. Our results suggest there may be ample opportunity to build on the current science instruction of elementary‐level teachers to bring their instruction into alignment with the NGSS. We found that teachers’ perceive professional development, school culture, and access to additional instructional resources to be essential to their adoption of the NGSS practices.     

Improved Roundoff Error Analysis for Precomputed Twiddle Factors

The accurate precomputation of the twiddle factors is necessary in order to perform discrete trigonometric transforms. This paper presents both worst case and average case analysis of roundoff errors occurring in eight precomputation methods of twiddle factors. We are interested in methods with small roundoff errors, low complexity and using only little computer memory. Numerical tests confirm the theoretical results.     

Worst and Average Case Roundoff Error Analysis for FFT

This paper presents both worst case and average case analysis of roundoff errors occuring in the floating point computation of fast Fourier transform (FFT) with precomputed twiddle factors and shows the strong influence of precomputation errors on the numerical stability of FFT. Numerical tests confirm the theoretical results.This revised version was published online in October 2005 with corrections to the Cover Date.     

格值模型的初等类及几点注记

本文证明了在有限值格下,一个模型类是初等类当且仅当它对超积和初等等价封闭,同时值格需有强特征式,语言应附有相应的零元关系符号。     

The DESTIN: Preservice Teachers' Drawings of the Ideal Elementary Science Teacher

The aim of this study is to report findings from the Drawing‐Elementary‐Science‐Teacher‐Ideal‐Not, or the DESTIN procedure. The study utilizes a simple drawing procedure accompanied by a narrative and discussion for understanding preservice teachers' images of science, science teaching, and the science teacher. Ninety drawings from two sections of an elementary science methods course were analyzed. Looking at the pre‐drawings from the beginning of the semester and post‐drawings done at the end of the semester, the findings relate the value of using drawings in teacher education and the usefulness of this procedure to promote discussions about science teaching, the construction of new images and practices for teaching elementary science, and teacher identity. The DESTIN procedure has potential as a productive activity for teacher education and long‐term professional development by making more explicit teachers' views of science teaching and learning and their past experiences as science learners.     

大基数与Chang氏模型C

本文研究了一些基数在Ｃｈａｎｇ氏模型Ｃ中的存在性，证明发如下结果：（１）如果Ｋ是弱紧基数，则Ｋ在Ｃ中也是弱紧基数，（２）如果Ｋ是ｉｎｅｆｆａｂｌｅ基数，则Ｋ在Ｃ中也是ｉｎｅｆｆａｂｌｅ基数。（３）如果Ｋ是完全ｉｎｅｆｆａｂｌｅ基数，则Ｋ在Ｃ中也是完全ｉｎｅｆｆａｂｌｅ基数。（４）设Ｊ：Ｃ→Ｃ为初等嵌入，Ｋ为最小变动的基数，则Ｋ在Ｃ中完全ｉｎｅｆｆａｂｌｅ基数，且是完全Ｒａｍｓｅｙ基数。