Temporal Contingency as an Independent Component of Parenting Behavior

Several theoretical conceptions emphasize the importance of prompt responses to infant's signals in providing them with early causal experiences. The present paper examines if a maternal tendency toward prompt responses can be identified by distributional analyses of maternal response latencies and if this response tendency can be shown for different communicative channels (in verbal/vocal, nonverbal, intermodal communication). In addition, the paper focuses on the relation between the temporal contingency of maternal behavior and measures of maternal interactional quality. Interactional sequences of 54 mother and 3-month-old infant dyads were analyzed using microanalytical assessment techniques and ratings of interactional quality. Distributional analyses of maternal expressions during face-to-face encounters revealed that promptness of responses toward infant signals with a short latency is a typical response tendency in maternal behavior. There are, however, individual differences between mothers, indicating that this response tendency is expressed in different communicative channels by individual mothers. This is shown by low correlations between the contingency indices of different communicative channels. The relation between contingency and rated indicators of interactional quality turned out to be rather small, indicating that maternal contingency may be conceptualized to contribute an independent factor to the quality of maternal interactional behavior.     

GEOMETRIC AND ALGEBRAIC APPROACHES IN THE CONCEPT OF “LIMIT” AND THE IMPACT OF THE “DIDACTIC CONTRACT”

The present study explores students’ abilities in conversions between geometric and algebraic representations, in problem- solving situations involving the concept of “limit” and the interrelation of these abilities with students’ constructed understanding of this concept. An attempt is also made to examine the impact of the “didactic contract” on students’ performance through the processes they employ in tackling specific tasks on the concept of limit. Data were collected from 222 12th-grade high school students in Greece. The results indicated that students who had constructed a conceptual understanding of limit were the ones most probable to accomplish the conversions of limits from the algebraic to the geometric representations and the reverse. The findings revealed the compartmentalized way of students’ thinking in non-routine problems by means of their performance in simpler conversion tasks. Students who did not perform under the conditions of the didactic contract were found to be more consistent in their responses for various conversion tasks and complex problems on limits, compared to students who, as a consequence of the didactic contract, used only algorithmic processes.     

Using diagrams as tools for the solution of non-routine mathematical problems

The Mathematics education community has long recognized the importance of diagrams in the solution of mathematical problems. Particularly, it is stated that diagrams facilitate the solution of mathematical problems because they represent problems’ structure and information (Novick & Hurley, 2001; Diezmann, 2005). Novick and Hurley were the first to introduce three well-defined types of diagrams, that is, network, hierarchy, and matrix, which represent different problematic situations. In the present study, we investigated the effects of these types of diagrams in non-routine mathematical problem solving by contrasting students’ abilities to solve problems with and without the presence of diagrams. Structural equation modeling affirmed the existence of two first-order factors indicating the differential effects of the problems’ representation, i.e., text with diagrams and without diagrams, and a second-order factor representing general non-routine problem solving ability in mathematics. Implicative analysis showed the influence of the presence of diagrams in the problems’ hierarchical ordering. Furthermore, results provided support for other studies (e.g. Diezman & English, 2001) which documented some students’ difficulties to use diagrams efficiently for the solution of problems. We discuss the findings and provide suggestions for the efficient use of diagrams in the problem solving situation.     

The contribution of system and control theory to new technologies

Over the last five decades, modem directions in technological areas such as wireless networks and communications, complex robotic systems, satellites and space structures have been immensely benefited by the use of system and control＇s conceptual framework. Estimation, stability, controllability, robustness, optimality, adaptation, information and statistical engineering are only some of the fundamental ingredients of the so-called new and emerging technologies, which are within the collective preview of this paper. Furthermore, these two, contrarily to technological trends, well established fields of science have been continuously supported by formal modelling techniques, and advanced computational and simulation tools, which enable the analysis and design of new powerful and effective methodologies. Consequently, in this article the authors＇ aim follows two equal directions. At first, the authors would like to provide a profusion of many practical examples and real life problems arising in different application areas that may have in the past abstractly engaged the authors＇ attention and have offer a wealth of opportunities for creative system modelling and practical solutions development. That is the core of our paper. However, in order to be more explicit, and to further illustrate the authors＇ thoughts, the case of a tele-medicine-assisted home support system is used; a system of great interest in the emerging field of information technology and medical health care. Secondly, by developing the necessary conceptual framework and some more efficient methods, important and straightforwardly challenges are inevitably derived. Moreover, a strong effort to develop a formal approach requires the definition of a generic system framework. It is a central objective of this paper to clarify and unify the alternative notions of a ＂conceptual model＂ and thus, to create a basis for the systematic development of formal methods, control/information architectures and decision-making strategies. AMS （Classification）： 97U50, 97U70, 97U80, 97D99.     

Three-dimensional kinematic analysis of the snatch of elite Greek weightlifters

We investigated the linear kinematics and the change in energy of the barbell and the angular kinematics of the trunk and leg during the snatch technique of 12 elite male Greek weightlifters under competitive conditions after the new weight classification. Two S-VHS cameras operating at 60 Hz were used to record the lifts. The spatial coordinates of selected points were calculated using the direct linear transformation procedure; after digital filtering of the raw data, the angular displacements and angular velocities were calculated for the hip, knee and ankle joints. The following variables were also calculated for the barbell: vertical and horizontal displacement, vertical linear velocity and acceleration, external mechanical work and power output. The results revealed that all weightlifters flexed their knees during the transition phase, independently of their weight category. This indicates that the athletes use the elastic energy produced during the stretch–shortening cycle to enhance their performance. In nine athletes, we found that the barbell trajectory did not cross a vertical reference line that passed through the initial position of the barbell. The vertical linear velocity of the barbell was increased continuously from the beginning of the movement until the second maximum extension of the knee joint, with no notable dip being observed. Regarding the change in energy of the barbell, we found that the mechanical work for the vertical displacement of the barbell in the first pull was significantly greater than the mechanical work in the second pull. In contrast, the estimated average mechanical power output of the athletes during the vertical displacement of the barbell was significantly greater in the second pull than in the first pull. We conclude that the major elements of the snatch technique of elite Greek weightlifters have not been aff ected by the new weight classification.     

Learning about web accessibility: A project based tool-mediated approach

Many websites remain inaccessible for people with disabilities, despite the availability of relevant guidelines and tools. This is mainly due to lack of appropriate training of Web designers on accessibility technology. In this paper, a project based learning activity designed to instruct Web accessibility guidelines and good design practices is presented. The activity is mediated by a web-based learning environment, which presents real-world examples of accessibility impasses that arise when certain, established guidelines are violated, and then provides advice on how to avoid or resolve them. The learning material contained in the tool is offered through a faceted browsing approach, thus enabling active exploration by the learner. A within-subjects case study compared the learning effectiveness of traditional academic instruction (pre-condition) with the proposed project based activity (post-condition) in the context of a University course. A significant improvement in students’ academic performance and perceived learning was found.     

Myosin heavy chain isoform composition in the deltoid and vastus lateralis muscles of elite handball players

ABSTRACT

The purpose of the present study was to compare the myosin heavy chain (MHC) isoform composition of the deltoid and vastus lateralis muscles of the dominant and non-dominant limbs in handball players. Eleven male Greek elite handball players (age 22.6 ± 1.9 yrs, training experience 10.6 ± 2.1 yrs, height 184.1 ± 4.1 cm, and weight 81.0 ± 12.5 kg) participated in the study. Four muscle biopsies were obtained from the dominant and non-dominant deltoid and vastus lateralis muscles during the in-season period. The MHC composition was determined using SDS-PAGE. No significant difference was found between the dominant and non-dominant muscles; Deltoid muscle: MHC I [(95%CI = ?1.22, 0.33), P = 0.228], MHC ΙΙa [(95%CI = ?0.32, 1.59), P = 0.168] and MHC IIx [(95%CI = ?1.49, 1.10), P = 0.749]; Vastus lateralis muscle: MHC I [(95%CI = ?0.38, 0.63), P = 0.586], MHC ΙΙa [(95%CI = ?0.50, 0.65), P = 0.783] and MHC IIx [(95%CI = ?1.08, 0.42), P = 0.355]. The findings of the present study indicate that the greater use of the dominant limbs for throwing actions and body movements in handball do not lead to altered MHC isoform composition compared to the non-dominant limbs.     

The effect of different goals and self-recording on self-regulation of learning a motor skill in a physical education setting

This study examined the effect of different goals (process, performance outcome, and multiple goals) and self-recording on self-regulation of learning a dart-throwing skill. Participants were 105 fifth and sixth graders who were randomly assigned to six (3 Goal type × 2 self-recording) experimental and one control group. Results showed a positive effect of self-recording on students’ performance, while no difference was found between the goal conditions. Moreover, goal group students made more technical attributions and adaptive inferences compared to the control group students. Results are discussed with reference to self-regulated learning, the pursuit of multiple goals and self-recording in physical education.     

On the differentiation of achievement goal orientations in physical education: a Rasch analysis approach

In two cross‐sectional studies, we investigated to what extent elementary (Study 1) and middle school (Study 2) students pursue similar, yet distinct, mastery‐related and performance‐related goals in physical education. We found that students were more likely to endorse outcome goals in conjunction with mastery‐related goals and ability goals in conjunction with normative goals. Rasch modelling suggested that students tended to endorse mastery‐approach goals than learning and outcome goals and that they tended to favour ability goals than performance‐approach goals. Differential item functioning analyses showed that autonomously motivated students were more likely to endorse learning goals and mastery‐approach goals and less likely to endorse outcome goals than less autonomously motivated students. They were also more likely to endorse ability goals and less likely to endorse normative goals than controlled motivated students. Results are discussed within the achievement goal framework and the self‐determination theory.     

A model on the cognitive and affective factors for the use of representations at the learning of decimals

In a previous article of the same journal, we have discussed the interrelations of students’ beliefs and self‐efficacy beliefs for the use of representations and their respective cognitive performance on the learning of fraction addition. In the present paper, we confirm a similar structure of cognitive and affective factors on using representations for the concept of decimals and mainly we discuss the various interrelations among those factors. Data were collected from 1701 students in Grades 5–8 (11–14‐years‐old). Results revealed that multiple‐representation flexibility, ability on solving problems with various modes of representation, beliefs about the use of representations and self‐efficacy beliefs about using them constructed an integrated model with strong interrelations that has differences and similarities with the respective model concerning the concept of fractions.