The legacy of Nikola Tesla
The AC system that he helped to usher in     

D P Sen Gupta 《Resonance》2007,12(3):54-69

Alternating Current (AC) is used all over the world today. In India we use AC at 50 Hz (cycles per second) and in USA and Canada at 60 Hz. During the latter part of the 19th century, even during the early part of the 20th century, Direct Current or DC was widely used. Had we continued with DC, electricity would not have been as widely available as it is today and its use would have been cumbersome, costly and severely restricted. We owe it mainly to the Serbian genius Nikola Tesla that electricity has reached almost every nook and corner of most continents.  相似文献   

Results of an assessment to identify potential barriers to sustainable agriculture on American Indian reservations in the Western United States     

Loretta Singletary  Staci Emm  Fara Ann Brummer  George C. Hill  Steve Lewis  Vicki Hebb 《The Journal of Agricultural Education and Extension》2016,22(4):375-387

Purpose: This paper reports the results of survey research conducted with tribal producers between 2011 and 2012 on 19 of the largest American Indian reservations in Idaho, Nevada, North Dakota, Oregon, South Dakota, and Washington. The purpose of the research was to identify potential barriers to sustainable agriculture on reservation lands. This article reports the results of this research in an effort to promote Extension professionals' understanding of these barriers, which may help to improve outreach programs on American Indian reservations. Understanding the obstacles to sustaining agriculture that American Indian tribes face may inform international agricultural outreach efforts to increase food security targeting indigenous and tribal peoples worldwide.

Design/Methodology/Approach: American Indian agricultural producers comprised the study group. Study objectives included: (1) identify agricultural and natural resource issues of greatest concern to a self-selected sample of tribal agricultural producers on reservation lands; (2) evaluate access to Extension and other US Department of Agriculture outreach and assistance programs; and (3) evaluate the quality of these programs in terms of their relativity to tribal needs.

Findings: Study results indicate that tribal agricultural producers surveyed ranked 29 of 39 agricultural and natural resource issues as a concern. Similarly, they rated access to and quality of outreach programs as fair. Further, tribal producers operating on reservation trust land rated issues more severely than did tribal producers operating on fee simple lands.

Practical Implications: Results of this research will help Extension and other outreach professionals to understand the barriers indigenous and tribal peoples face in sustaining agricultural operations, particularly tribal groups living on federally reserved trust lands, such as American Indians. An increased understanding can inform agricultural policy-makers and outreach professionals in improving programs designed to increase agricultural sustainability, improve food security, enhance economic well-being and improve quality of life of indigenous and tribal peoples worldwide.

Originality/Value: This research provides important information to agricultural policy-makers and Extension professionals striving to sustain agricultural productivity and enhance food security with indigenous and tribal peoples.  相似文献   

Sign and phonology     

Moores DF 《American annals of the deaf》2001,146(1):3-4

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无线移动数字图书馆系统中多媒体检索的同步模式     

党德鹏  周立柱 《上海大学学报(英文版)》2006,10(5):409-414

1IntroductionRecent advances in wireless communication,digitallibrary,distributed multi media,massive storage,andmobile computing technologies are sti mulating the de-velopment of mobile multi media digital library systems(M2DLS)that allow mobile clients to access multi me-dia material anywhere and anyti me over a cellular ra-dio network[1,2].In M2DLS,multi media objects,ingeneral,can be composed of multiple media streamssuch as audio and video,whose retrieval must proceedso as to not only …  相似文献   

Changing the Behavior of Behavior Changers     

John D. Krumboltz 《Counselor Education & Supervision》1967,6(Z3):222-229

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Academic socialization,parental educational expectations,and academic self‐efficacy among Latino adolescents     

Fernanda L. Cross  Aixa D. Marchand  Michael Medina  Andrea Villafuerte  Deborah Rivas‐Drake 《Psychology in the schools》2019,56(4):483-496

This study examined the direct association between parental educational expectations and adolescents’ academic self‐efficacy, as well as the moderating influence of parental academic socialization messages. Participants were 148 Latino parent–adolescent dyads with the majority of Mexican origin (80.4%). Most of the parent participants were mothers (85.8%). Adolescents were 13 (46%) or 14 (54%) years of age, and 53% identified as female. Adolescents reported their academic self‐efficacy and perceptions of their parents’ educational expectations; parents reported on their academic socialization messages of shame/pressure and effort regarding academics. The results suggest that, after accounting for parents’ level of education and immigrant status, parental educational expectations were positively associated with adolescent academic self‐efficacy. This association was stronger among adolescents whose parents reported transmitting fewer messages of shame/pressure and academic effort. These results point to the importance of nuances in the content and type of academic socialization messages within Latino families.  相似文献   

Mathematical Modeling in the Primary School: Children's Construction of a Consumer Guide     

Lyn D. English 《Educational Studies in Mathematics》2006,63(3):303-323

This paper examines 6th grade children's local conceptual development and mathematization processes as they worked a comprehensive mathematical modeling problem (creating a consumer guide for deciding the best snack chip) over several class periods. The children and their teachers were participating in a 3-year longitudinal teaching experiment in which sequences of mathematical modeling problems were implemented from the 5th grade (10 years of age) though to the 7th grade. In contrast to traditional problem solving, mathematical modeling requires children to generate and develop their own mathematical ideas and processes, and to form systems of relationships that are generalizable and reusable. Reported here is a detailed analysis of the iterative cycles of development of one group of children as they worked the problem, followed by a summary of the mathematization processes displayed by all groups. Children's critical reflections on their models are also reported. The results show how children can independently develop constructs and processes through meaningful problem solving. Children's development included creating systems for operationally defining constructs; selecting, categorizing, and ranking factors; quantifying quantitative and qualitative data; and transforming quantities.  相似文献   

Can research on science learning and instruction inform standards for science education?   总被引：1，自引：0，他引：1  

Linn  Marcia C.  diSessa  Andy  Pea  Roy D.  Songer  Nancy B. 《Journal of Science Education and Technology》1994,3(1):7-15

We contrast the current science education reform effort with the reforms of the 1960s and suggest how the current effort could be enhanced. We identify insights from recent research that we believe can inform the reform process, in particular, to reach all science students and also impart a cohesive view of science. We propose an alternative models view of scientific explanation and show how this view would contribute to reforms of (1) course goals, (2) social aspects of science learning, (3) instructional practices, and (4) roles for technology.This paper summarizes discussions and debates that the authors have had over the last few years. The dialogue stems, in part, from our joint participation in the American Educational Research Association Special Interest Group on Education in Science and Technology (AERA SIG:EST) leadership. This paper communicates the spirit of our thinking and does not necessarily reflect the view of SIG:EST, or any other organization.We gratefully acknowledge the support of National Science Foundation Grant MDR-9253462 in work related to this paper. We appreciate helpful comments from Eileen Lewis and the Computer as Learning Partner group.This material is based upon research supported by the National Science Foundation under grant RED-9155744. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and not necessarily reflect the views of the National Science Foundation.  相似文献   

The presentation of statistical information     

Gloria D. Feliciano  Richard D. Powers  Bryant E. Kearl 《Educational technology research and development : ETR & D》1963,11(3):32-39

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Examining the research base of the regular education initiative: efficacy studies and the adaptive learning environments model   总被引：1，自引：0，他引：1  

D P Hallahan  C E Keller  J D McKinney  J W Lloyd  T Bryan 《Journal of learning disabilities》1988,21(1):29-35, 55

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