The Reliability and Validity of the Fitjump Photoelectric Cell System for Determining Vertical Jump Height

ABSTRACT

The aim of this investigation was to assess the reliability and validity of the Fitjump system. Fifty-seven participants (age = 22.62 ± 5.24 years, height = 180.69 ± 12.53 cm, body mass = 75.61 ± 9.56 kg) performed three countermovement jump (CMJ) and squat jump (SJ) with a 1-week interval for test and retest reliability. For validity, the participants performed the same jump protocol on the force platform while being simultaneously measured with the Fitjump system. There was excellent test–retest reliability of the Fitjump system for CMJ and SJ with high intraclass correlation coefficient (ICCs) (0.97 and 0.97, respectively), low coefficient variation (CVs) (2.3% and 2.4%, respectively), and low typical error of estimate [(TEE (%)] (4.0% and 4.4%, respectively). For validity, ICCs were extremely high for CMJ and SJ (0.93 and 0.94, respectively), with low TEE (%) (2.9% and 2.0%, respectively). However, Fitjump overestimated jump height for CMJ and SJ (3.54 and 3.37 cm, respectively; p < 0.001) when compared with the force platform. As a conclusion, the Fitjump system demonstrated excellent test–retest reliability and high relationship with a systematic bias for validity. Therefore, the Fitjump system can be used as a portable tool for monitoring vertical jump changes over time, but it should not be used interchangeably with a force platform.     

Exploring challenges of assessing pre-service science teachers’ pedagogical content knowledge (PCK)

The purpose of this paper is to report on the challenges we faced in designing an instrument aimed at measuring pre-service science teachers’ topic-specific pedagogical content knowledge (PCK). After the instrument was conceptualised and developed, it was administered to 30 pre-service chemistry teachers. The findings suggest that the instrument can be used as a teaching tool to enhance pre-service science teachers’ topic-specific PCK along with some limitations. The discussion focuses on the implications of the aforementioned PCK assessment tool for enhancing pre-service science teachers’ topic-specific PCK and the challenges associated with measuring and enhancing pre-service science teachers’ PCK. Finally, our discussion focuses on the ways in which science-teacher educators can engage in transforming the concept of PCK and its use for research and professional development.     

Total thyroidectomy is safer with identification of recurrent laryngeal nerve

Objective: To investigate the effect of recurrent laryngeal nerve (RLN) identification on the complications after total thyroidectomy and lobectomy. Methods: Total 134 consecutive patients undergoing total thyroidectomy or thyroid lobectomy from January 2003 to November 2004 were investigated retrospectively. Patients were divided into two groups: RLN identified (Group A) or not (Group B). The two groups were compared for RLN injury and hypocalcaemia. Results: The numbers of patients and nerves at risk were 71 and 129 in Group A, and 63 and 121 in Group B, respectively. RLN injury in Group A (0) was significantly lower than that in Group B (5[7.9%]) patients, 7 [5.8%] nerves) for the numbers of patients (P=-0.016) and nerves at risk (P=0.006). Temporary hypocalcaemia was significantly higher in Group A than in Group B (14 [24.1%] vs 6 [10.3%], P=0.049).Permanent complications in Group B were significantly higher than those in Group A (13 [20.6%] vs 4 [5.6%], P=0.009). Conclusion: RLN injury was prevented and permanent complications were decreased by identifying the whole course and branches of the recurrent laryngeal nerve during total thyroidectomy.     

Understanding The Impact of an Apprenticeship-Based Scientific Research Program on High School Students’ Understanding of Scientific Inquiry

The purpose of this study was to understand the impact of an apprenticeship program on high school students’ understanding of the nature of scientific inquiry. Data related to seventeen students’ understanding of science and scientific inquiry were collected through open-ended questionnaires. Findings suggest that although engagement in authentic scientific research helped the participants to develop competency in experimentation methods it had limited impact on participants’ learning of the implicit aspects of scientific inquiry and NOS. Discussion focuses on the importance of making the implicit assumptions of science explicit to the students in such authentic scientific inquiry settings through structured curriculum.     

An experimental investigation of properties of polyethylene reinforced with Al powders

Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness, melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature. The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the introduction of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values.     

Cyclic codes over some finite quaternion integer rings

In this paper, cyclic codes are studied over some finite quaternion integer rings with respect to the quaternion Mannheim distance.     

ARGUMENTATION AND STUDENTS’ CONCEPTUAL UNDERSTANDING OF PROPERTIES AND BEHAVIORS OF GASES

The purpose of this study was to explore the impact of argumentation-based pedagogy on college students?? conceptual understanding of properties and behaviors of gases. The sample consists of 108 students (52 in the control group and 56 in the intervention group) drawn from 2 general chemistry college courses taught by the same instructor. Data were collected through pre- and post-tests. The results of the study show that the intervention group students performed significantly better than the control group students on the post-test. The intervention group students also showed significant increase in their test scores between pre- and post-test. While at least 80?% of the students in the intervention group abandoned their initial ideas on all of the 17 alternative conceptions that were identified by the authors but one, the percent of student abandoning their initial ideas in the control group was less than 50. The discussion focuses on the implications of these results for addressing students?? alternative conceptions, promoting the argumentation?Cpedagogy in college science courses and the challenges associated with the use of argumentation in college science classrooms.     

The MacWilliams identity for m-spotty Rosenbloom–Tsfasman weight enumerator

The communication systems and disk or tape memory can sometimes cause clusters of errors, namely burst errors. There have been many designs in order to detect and even correct such errors. Recently, a new class of codes called m-spotty byte error correcting codes has found applications in high speed memory systems that employ random access memory chips wide Input/Output data, especially at 8, 16, or 32 bits. The MacWilliams identity provides the relationship between the weight distribution of a code and that of its dual code. Also, an interesting new metric called Rosenbloom–Tsfasman metric has been studied as an alternative metric for linear codes recently. In this paper, we combine these two interesting topics and introduce the m-spotty Rosenbloom–Tsfasman weights and the m-spotty Rosenbloom–Tsfasman weight enumerator of a binary code. Moreover, we prove a MacWilliams identity for the m-spotty Rosenbloom–Tsfasman weight enumerators.     

Young children's perceptionsof scientists: a preliminary study

Background

Since the 1950s, there has been a growing body of research dealing with perceptions children have of scientists. Typically, research studies in this area have utilized children's drawings in an effort to discern what those perceptions are. Studies assessing perceptions children have of scientists have shown that children have stereotypical images of scientists. Although there is no direct evidence to demonstrate the link between children's images of science and scientists with their career choice, several researchers (including this researcher) have assumed that children's attitudes towards science are greatly influenced by their perceptions of science and scientists.

Purpose

This study aimed to find out if there was a difference in the way 5- to 8-year-old children drew scientists, taking account of age, gender and socio-economic status.

Sample

For this study a convenience sample of 30 young children was used. Participants included young children between the ages of 5 and 8 years from a public elementary school in Ankara, the capital city of Turkey. Although the sample of the study was obtained from one school in a metropolitan area, children involved in this preliminary study were from very different socio-economic backgrounds. As the sample size is very small for making comparisons, it was intended to have a similar number of children from different age groups and socio-economic backgrounds and both genders.

Design and methods

The researcher worked individually with each child who participated in this study in an interview setting. Although each child was asked a set of standard questions, and given a standard set of directions, each interview session was informal enough to allow the researcher to gain additional information about children's drawings and to clarify any of their responses. During the interview sessions, children's responses were noted by the researcher. Before the children were asked to draw their picture of a scientist, they were offered a set of coloured pencils or crayons and told to feel free to colour their drawing or any parts of it they would like to accentuate. At the end of the interview and drawing sessions, the researcher went through all the drawings and notes to get a ‘feel’ for and ascertain what was being said, identifying key themes in each drawing.

Results

The most common scientist type drawn in this study was the stereotypical scientist type: someone who conducts research, or someone who tries to invent a new material. But unlike previous studies, around 35% of the scientist figures drawn (n = 15) were of the social scientist type. Stereotypical images drawn by the current study participants included symbols of research, such as scientific instruments and laboratory equipment of all kinds, and symbols of knowledge, principally books and cabinets, technology and the products of science. An interesting finding of this study was that perceptions of young children differed due to their age. Children at the age of 8 years drew non-stereotypical scientist images, and they drew more detail than did their younger peers. When children were compared in terms of their gender, no significant differences were observed between girls and boys. But on the other hand, none of the boys drew female scientists, and five out of 30 children who were girls drew female scientists. While children of parents with lower socio-economic status drew more stereotypical scientist images, children of parents with higher economic status drew different images of scientists, a result which showed us that the scientist perceptions of young children differ with socio-economic status.

Conclusions

Emergent from this research has been a non-stereotypical perception of scientists, and some evidence exists that such a non-stereotypical perception differs due to age and socio-economic status. While these images may seem amusing, they also provide a reflection of the image that children have about what a scientist looks like. These images may have a powerful impact on present functioning and future plans of young children.