Mathematics teaching life histories in the study of teachers' perceptions of change

The aim of this paper is to discuss teachers' perceptions of change in their thought and/or practice over time and their perceptions of what kind of experiences or challenges might have influenced those changes. Two mathematics teaching life histories of Brazilian teachers are examined, considering a context of curriculum development in the state of São Paulo, Brazil. Reflection on teachers' thought and practice and interest in their own development, including interest in their own learning of mathematics, seemed to be the most important internal aspects influencing change and development. Close support seemed to be the most important external aspect. The retrospective analysis put a good face on personal change and development. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

A comparison of performance indexes in DC-DC converters under different stabilizing state-dependent switching laws

This paper deals with the problem of establishing stabilizing state-dependent switching laws in DC-DC converters operating at continuous conduction mode (CCM) and comparing their performance indexes. Firstly, the nature of the problem is defined, that is, the study of switched affine systems, which may not share a common equilibrium point. The concept of stability is, therefore, broadened. Then, the central theorem is proposed, from which a family of switching laws can be derived, namely the minimum law and the hold state law. Some of these are proved to stabilize the basic DC-DC converters and then, their performances are compared to another law, from a previous work, by simulation, where a great reduction in overshoot is obtained. © 2011 IEEE.

Proyecto de informe del Octavo Período de Sesiones del CEGAN: evaluación de la instrumentación de la Estrategia Internacional del Desarrollo para América Latina y el Caribe, teniendo en cuenta la crisis económica internacional = Draft report of the Eighth Session of CEGAN: appraisal of the implementation of the International Development Strategy for Latin America and the Caribbean, taking into account the current international economic crisis

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Quality of performance of the operation of sugarcane mechanized planting in day and night shifts

The sugarcane mechanized planting is becoming increasingly widespread in Brazil due to a higher operability and better working conditions offered to workers compared to other types of planting. Studies related to this topic are insufficient or scarce in Brazil. In this context, the aim of this study was to evaluate the operation quality of sugarcane mechanized planting in two operation shifts, by means of statistical process control. The mechanized planting was held on March 2012 and statistical design was completely randomized with two treatments, totaling 40 replications for the day shift and 40 replications for the night shift. The variables evaluated were: speed, engine rotation, engine oil pressure, water temperature of the engine, effective field capacity and the time consumption hourly and effective fuel. The use of statistical control charts showed that random intrinsic do not cause this process. The tractor alignment error showed outliers in the day and night shifts operations, indicating a possible delay in receiving the signal. The water temperature of the engine and the effective fuel consumption showed lower variability in nighttime operation with average values of 81°C and 22.66 L ha-1, respectively. The hourly fuel consumption had greater variability and consequently lower quality during the night of the operation, with an average consumption of 25.46 L h-1 while the day shift showed 26.86 L h-1.

On the parameters of performance of combined refrigeration and power plants

Combined Refrigeration and Power (CRP) plants generate power and refrigerate a thermal load simultaneously from the same fuel. The overall efficiency is a parameter based on the first law generally used to quantify the fuel saving, in the sense that a plant that has greater overall efficiency saves more fuel than others to generate the same useful energy. However, the literature shows that the overall efficiency and other parameters of performance are defined in several different ways. This heterogeneity is not desirable when considering a coherent and universally accepted parameter of performance based on the first law. In this work, some parameters found in the literature are critically analyzed in order to indicate the most proper one. The indicated parameter is then formally analyzed in order to verify its mathematical consistency. The primary energy rate is considered the most well-suited parameter based on the first law to characterize the performance of a CRP plant. © 2013 Elsevier Ltd and IIR.

Perceptions of environmental change and use of traditional knowledge to plan riparian forest restoration with relocated communities in Alcantara, Eastern Amazon

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Perceptions of educators and students about using fluoridated mouthwashes

Purpose: The objective of this study was to assess the perceptions and opinions of public school teachers and students in the city of Araçatuba, SP, Brazil, on the importance of using fluoridated mouthwashes, the difficulties of the method and the procedure in general. Methods: Students from grades 5 through 8 in schools with and without dental services were asked about their opinion on the use of fluoridated mouthwashes. The educators answered questions about the importance of preventive methods in oral health and the difficulties in performing those methods at school. Data were collected using a faces scale, a categorization method, and a Likert scale with five levels of responses to check the level of agreement with the questions. Results: The sample consisted of 264 (40.3%) teachers and 5,788 (73.6%) students. A total of 254 (96.2%) and 72 (27.3%) teachers responded favorably to the first and second questions, respectively. A total of 1,128 (19.5%) students had negative feelings about the fluoridated mouthwash. Conclusion: The majority of the teachers supported the use of fluoridated mouthwashes; however, a large number of teachers believed that the practice disrupts the class routine. Most of the students had a positive opinion about the use of fluoridated mouthwash, although they highlighted some negative aspects, which were overcome by the benefits that the method provides.

The canonical correlation between the biological markers of performance and physical fitness in high level judo athletes

The objective of this research was to verify the relationship between biological markers of performance of elite judo athletes and performance in different physical fitness tests. Twenty-one judo athletes were involved in the present observational and correlational study. Dermatoglyphic variables and the 2D:4D digit ratio were considered as biological markers, while the physical fitness variables analyzed were body fat, maximal strength, muscular power, the aerobic and anaerobic profile, and performance in specific tests. The statistics involved canonical correlations and a multivariate technique. A high and significant canonical correlation was observed between groups of variables, the first expressed by 1=0.999 (p<0.0001) and the second by 2=0.997 (p<0.001). It appears that, beyond height and body mass, total ridge count, pattern intensity for fingers and 2D:4D had more canonical loading. The physical fitness component of the first canonical variable incorporated, with high intensity were: the sum of skinfold thickness, the bench press onerepetition maximum (1RM), upper and lower body aerobic power. In the second canonical variable, physical fitness was composed of the squat 1RM, suspension time on the bar, the SJFT-index, and mean power during the upper body Wingate test. The data of this investigation showed the interdependence between biological markers of performance and physical fitness in high level judo athletes.

Perceptions of Procedural and Distributive Justice in the September 11th Victim Compensation Fund

The September l1th Victim Compensation Fund (the Fund) was created in response to the terrorist attacks of September 11, 2001. Much has been written about the Fund, both pro and con, in both popular media and scholarly literature. Perhaps the most widely used term in referring to the Fund is "unprecedented." The Fund is intriguing for many reasons, particularly for its public policy implications and its impact on the claimants themselves. The federal government has never before provided compensation to victims of terrorism through a special master who had virtually unlimited discretion in determining awards. Consequently, this formal allocation of money by a representative of the federal government to its citizens has provided an opportunity to test theories of procedural and distributive justice in a novel context. This article tests these theories by analyzing the results of a study of the Fund's claimants. Part I provides general background, summarizes existing commentary on the Fund, and discusses prior research on social justice that is relevant to the 9/11 claimants' experiences with the Fund. Part II of this article describes the methodology behind the study, in which seventy-one individuals who filed claims with the Fund completed surveys about their experiences with and perceptions of the Fund. Part III discusses the survey results. We found that participants were reasonably satisfied with the procedural aspects of the Fund, such as representatives' impartiality and respectful treatment. Participants were less satisfied, however, with the distributive aspects of the Fund, such as the unequal distribution of compensation and the reduction in compensation if claimants received compensation from other sources (e.g., life insurance). Part IV of this article addresses the implications of the study results for public policy and for theories of social justice.

Student and Faculty Perceptions of Technology’s Usefulness in Community College General Education Courses

Educational institutions of all levels invest large amounts of time and resources into instructional technology, with the goal of enhancing the educational effectiveness of the learning environment. The decisions made by instructors and institutions regarding the implementation of technology are guided by perceptions of usefulness held by those who are in control. The primary objective of this mixed methods study was to examine the student and faculty perceptions of technology being used in general education courses at a community college. This study builds upon and challenges the assertions of writers such as Prensky (2001a, 2001b) and Tapscott (1998) who claim that a vast difference in technology perception exists between generational groups, resulting in a diminished usefulness of technology in instruction. In this study, data were gathered through student surveys and interviews, and through faculty surveys and interviews. Analysis of the data used Kendall’s Tau test for correlation between various student and faculty variables in various groupings, and also typological analysis of the transcribed interview data. The analysis of the quantitative data revealed no relationship between age and perception of technology’s usefulness. A positive relationship was found to exist between the perception of the frequency of technology use and the perception of technology’s effectiveness, suggesting that both faculty members and students believed that the more technology is used, the more useful it is in instruction. The analysis of the qualitative data revealed that both faculty and students perceive technology to be useful, and that the most significant barriers to technology’s usefulness include faulty hardware and software systems,lack of user support, and lack of training for faculty. The results of the study suggest that the differences in perception of technology between generations that are proposed by Prensky may not exist when comparing adults from the younger generation with adults from the older generation. Further, the study suggests that institutions continue to invest in instructional technology, with a focus on high levels of support and training for faculty, and more universal availability of specific technologies, including web access, in class video, and presentation software. Adviser: Ronald Joekel