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71.
72.
Quantum algorithms are a field of growing interest within the theoretical computer science as well as the physics community. Surprisingly, although the number of researchers working on the subject is ever-increasing, the number of quantum algorithms found so far is quite small. In fact, the task of designing new quantum algorithms has been proven to be extremely difficult. In this paper we give an overview of the known quantum algorithms and briefly describe the underlying ideas. Roughly, the algorithms presented are divided into hidden subgroup type algorithms and in amplitude amplification type algorithms. While the former deal with problems of group-theoretical nature and have the promise to yield strong separations of classical and quantum algorithms, the latter have been proved to be a prolific source of algorithms in which a polynomial speed-up as compared to classical algorithms can be achieved. We also discuss quantum algorithms which do not fall under these two categories and give a survey of techniques of general interest in quantum computing such as adiabatic computing, lower bounds for quantum algorithms, and quantum interactive proofs.  相似文献   
73.
74.
Medicine has made increasing use of meta-analysis, largely as a quantitative procedure for combining results of clinical trials. Meta-analysis begins with a comprehensive review of the literature. The next step is a systematic analysis of the quality and content of each study. Finally, results are combined statistically and conclusions are drawn from this new overview of the data. This paper presents a brief historical perspective on the use of meta-analysis in medicine with emphasis on the medical library. The authors conclude that in the future, medical librarians will play a significant role in the application of this useful technique.  相似文献   
75.
What is the future for libraries and their librarians? In trying to give an answer to this pressing question we do not deal with utopian libraries of the next century, but with the library and the librarian of the next decade. The emphasis is on libraries within educational and research institutions, especially university libraries. We examine the changes confronting the library of the future and identify four key aspects of the library of the future. It will be (i) a gateway to information, whatever format this information comes in and wherever it is located; (ii) an expertise centre; (iii) a physical entity, not only in the sense of being a social meeting place and place of scholarly interaction, but also as a place where students and other users are provided with modern study facilities and adequate user support; and (iv) a collection centre of printed material. Such libraries can only take on an appropriate shape and will only survive if the institutions that librarians serve in meet the four criteria outlined above. We look at the demands that will be made on professional library knowledge and skills and the new job responsibilities and job attitudes required.  相似文献   
76.
以广西82名业余体校男运动员为研究对象,运用数理统计方法,探讨了快肌百分比与有关身体素质指标和生理指标的相关程度,以及拟合的指标对快肌百分比的影响,旨在为速度性运动项目的选材提供理论依据。  相似文献   
77.
浅谈体育教学中的语言艺术   总被引:1,自引:0,他引:1  
体育教学语言是教师向学生传授知识的载体,交流情感的方式及培养人才的工具,亦是影响教学效果的重要因素之一.通过对体育教学语言的分类、特点及其运用方法的论述,着重阐明了体育教学语言指令性、调节性和感染性特点;语言修养及教育性、准确性和生动性等要求.  相似文献   
78.
试述现代科学训练的主要特征   总被引:2,自引:0,他引:2  
根据现代运动训练学科的发展趋势,从运动训练的过程、人员机构和外部联系3个主要方面对现代科学训练的特征进行论述.  相似文献   
79.
Chaos theory, informational needs, and natural disasters   总被引:2,自引:0,他引:2  
This study applies chaos theory to a system-wide analysis of crisis communication in a natural disaster. Specifically, we analyze crisis communication during the 1997 Red River Valley flood in Minnesota and North Dakota. This flood, among the worst in modern American history, consumed entire metropolitan areas, displacing thousands of people. The conditions and decisions leading to the disaster, and the subsequent reactions are retraced. Communication related to river crest predictions (fractals), the shock at the magnitude of the crisis (cosmology episode), novel forms of reorganizing (self-organization), and agencies that aided in establishing a renewed order (strange attractors) are evaluated. Ultimately, we argue that preexisting sensemaking structures favoring rationalized, traditional views of a complex system led officials to make inappropriately unequivocal predictions and ultimately diminished the effectiveness of the region's crisis communication and planning.  相似文献   
80.
The purpose of this study was to determine test-retest reliability for the 1-mile, 3/4-mile, and 1/2-mile distance run/alk tests for children in Grades K-4. Fifty-one intact physical education classes were randomly assigned to one of the three distance run conditions. A total of 1,229 (621 boys, 608 girls) completed the test-retests in the fall (October), with 1,050 of these students (543 boys, 507 girls) repeating the tests in the spring (May). Results indicated that the 1-mile run/walk distance, as recommended for young children in most national test batteries, has acceptable intraclass reliability (.83 less than R less than .90) for both boys and girls in Grades 3 and 4, has minimal (fall) to acceptable (spring) reliability for Grade 2 students (.70 less than R less than .83), but is not reliable for children in Grades K and 1 (.34 less than R less than .56). The 1/2 mile was the only distance meeting minimal reliability standards for boys and girls in Grades K and 1 (.73 less than R less than .82). Results also indicated that reliability estimates remained fairly stable across gender and age groups from the fall to spring testing periods, with the exception of the noticeably improved values for Grade 2 students on the 1-mile run/walk test. Criterion-referenced reliability (P, percent agreement) was also estimated relative to Physical Best and Fitnessgram run/walk standards. Reliability coefficients for all age group standards were acceptable to high (.70 less than P less than .95), except for Fitnessgram standards for 5-year-old girls on the 1-mile test for both fall and spring and for 6-year-old boys and girls on the 1-mile test administered in the spring.  相似文献   
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