semPlot: Unified Visualizations of Structural Equation Models

Structural equation modeling (SEM) has a long history of representing models graphically as path diagrams. This article presents the freely available semPlot package for R, which fills the gap between advanced, but time-consuming, graphical software and the limited graphics produced automatically by SEM software. In addition, semPlot offers more functionality than drawing path diagrams: It can act as a common ground for importing SEM results into R. Any result usable as input to semPlot can also be represented in any of the 3 popular SEM frameworks, as well as translated to input syntax for the R packages sem (Fox, Nie, & Byrnes, 2013) and lavaan (Rosseel, 2012). Special considerations are made in the package for the automatic placement of variables, using 3 novel algorithms that extend the earlier work of Boker, McArdle, and Neale (2002). The article concludes with detailed instructions on these node-placement algorithms.     

The knowledge of orthography is a revolution in the brain

Brain adaptation to the type of informationthat is processed has been documented inseveral conditions in animals and humans.Illiteracy due to social reasons is a goodsource of information to investigate theadaptation mechanisms to the formal knowledgeof written language. In this paper, a series ofstudies addressing this topic are reviewed.Illiterate subjects and their carefullyselected controls were compared in severalexperimental conditions. It is concluded thatschooling and in particular the knowledge oforthography introduces in the brain newstrategies for information processing thatmanifest themselves in task performance, inbrain activation studies and in anatomicalstudies.     

The differential impact of academic self-regulatory methods on academic achievement among university students with and without learning disabilities

Although research on academic self-regulation has proliferated in recent years, no studies have investigated the question of whether the perceived usefulness and the use of standard self-regulated learning strategies and compensation strategies provide a differential prediction of academic achievement for university students with and without learning disabilities (LD). We developed and tested a model explaining interrelationships among self-regulatory variables and grade point average (GPA) using structural equation modeling and multiple group analysis for students with LD (n = 53) and without LD (n = 421). Data were gathered using a new instrument, the Learning Strategies and Study Skills survey. The results of this study indicate that students with LD differed significantly from students without LD in the relationships between their motivation for and use of standard self-regulated learning strategies and compensation strategies, which in turn provided a differential explanation of academic achievement for students with and without LD. These paths of influence and idiosyncrasies of academic self-regulation among students with LD were interpreted in terms of social cognitive theory, metacognitive theory, and research conducted in the LD field.     

Aerobic exercise did not have compensatory effects on physical activity levels in type 2 diabetes patients

Although exercise promotes beneficial effects in diabetic patients, some studies have questioned the degree of their importance in terms of the increase in total energy expenditure. In these studies, the decrease of physical activity levels (PAL) was referred as “compensatory effect of exercise”. However, our aim was to investigate whether aerobic exercise has compensatory effects on PAL in type 2 diabetes patients. Eight volunteers (51.1 ± 8.2 years) were enrolled in a supervised exercise programme for 8 weeks (3 d · wk^?1, 50–60% of VO₂ peak for 30–60 min). PAL was measured using tri-axial accelerometers in the 1st, 8th and 12th weeks. Biochemical tests, cardiorespiratory fitness, anthropometric assessment and body composition were measured in the 2nd and 11th weeks. Statistical analysis was performed using non-parametric tests (Friedman and Wilcoxon, P < 0.05). We found no significant differences in PAL between intervention periods, and participants spent the majority of their awake time in sedentary activities. However, the exercise programme generated a significant 14.8% increase in VO₂ peak and a 15% reduction in fructosamine. The exercise programme had no compensatory effects on PAL in type 2 diabetes patients, but improved their cardiorespiratory fitness and glycaemic control.     

Female Administrators: A Crack in the Glass Ceiling

This experimental study investigates the effects of gender of the evaluator, gender of the applicant, and gender of the reference source at the screening stage of the selection process. Specifically, male and female principals were asked to evaluate re´sume´s and reference letters of hypothetical male and female applicants for the focal position of assistant principal. In the context of selection of an assistant principal, the authors hypothesized that male principals would prefer male applicants and female principals would prefer female applicants. This hypothesis was based on the sex similarity-attraction paradigm. The sex similarity-attraction paradigm suggests that same-sex applicants will be regarded as more similar than opposite-sex applicants (Gallois, Callan & Palmer, 1992) and that applicants who are perceived as similar will be evaluated favorably (Cardy & Dobbins, 1986). Finally, although the authors anticipated that sex similarity-attraction would support an interaction effect between gender of applicant and gender of rater, as strengthened by gender of the reference letter source, the findings did not support this interaction. In fact, the main effect for gender of applicant indicates that hypothetical female administrator candidates are evaluated significantly higher than hypothetical male administrator candidates. This is contrary to about half of past selection research that suggested female applicants are given lower evaluations than male applicants. Thus, these results may be an indication that the evaluations of female applicants for administrative positions are improving to the extent that female applicants were more likely to be offered employment interviews than male applicants.     

The Radio and the Portuguese 1974 Revolution. The Military,the Radio Personnel and a Successful Cooperation

The importance of the media in the Portuguese 1974 Revolution is recognized by the military, politicians, and journalists. In this context, the major role of the radio broadcast in the course of events is undisputable. In the dawn of April 25, a popular Portuguese song was the start signal for the military coup and other counter signals followed, sounds that became symbols of the Revolution. Radio was the medium chosen by the Armed Forces Movement (MFA or Movimento das Forças Armadas in the original) to communicate with the parties involved in the coup and it was also used to inform the population of the goals and progress of the military operations. The following manoeuvres eventually transformed Radio Clube Português, one of the radio stations, in the commanding post of all the operations and the Portuguese people became aware of the MFA goals and victories by the bulletins that were broadcasted by the military on the radio. In a country with high illiteracy, radio played a crucial role in terms of information, which confirms its unquestionable centrality in the course of the April Revolution (also known as the Carnations Revolution). This study aims to explain how this process was achieved and it is based on the recollection of documents, archives, and other information. The recovery of testimonies and reconstruction of events allow us to explore the way military interacted with radio personnel and how radio logics prevailed and helped the military to successfully achieve their goals.     

Bangladeshi Science Teachers’ Perceived Importance and Perceived Current Practices in Promoting Science Education Through a Context-Based,Socio-scientific Framework

Science & Education - The paper reports a study that seeks to develop an instrument so as to explore Bangladeshi science teachers’ perceived importance and perceived current practices,...     

Zero dynamics and funnel control for linear electrical circuits

We consider electrical circuits containing linear resistances, capacitances and inductances. The circuits can be described by differential-algebraic input–output systems, where the input consists of voltages of voltage sources and currents of current sources and the output consists of currents of voltage sources and voltages of current sources. We generalize a characterization of asymptotic stability of the circuit and give sufficient topological criteria for its invariant zeros being located in the open left half-plane. We show that asymptotic stability of the zero dynamics can be characterized by means of the interconnectivity of the circuit and that it implies that the circuit is high-gain stabilizable with any positive high-gain factor. Thereafter we consider the output regulation problem for electrical circuits by funnel control. We show that for circuits with asymptotically stable zero dynamics, the funnel controller achieves tracking of a class of reference signals within a pre-specified funnel; this means in particular that the transient behavior of the output error can be prescribed and the funnel controller does neither incorporate any internal model for the reference signals nor any identification mechanism, it is simple in its design. The results are illustrated by a simulation of a discretized transmission line.     

Effect of a Hanging Exercise on the Epiphyseal Cartilage of the Humerus of Albino Rats

This study was designed to determine the number of days of pedometer monitoring necessary to achieve reliable and valid estimates of a 1-year average of step counts in adults based on either consecutive days (CD) or random days (RD) of data collection. Twenty-three participants (16 women; M age = 38 years, SD = 9.9) wore a Yamax SW 200 pedometer and recorded their step counts for 365 consecutive days. Nine measurement periods of various lengths were selected (2, 3, 4, 5, 6, 7, 14, 21, and 30 days). Each measurement period was randomly selected 10 times each for CD and RD from the larger database. For reliability and validity, two-way intraclass correlation coefficients and mean absolute percentage error (MAPE) were calculated, respectively. The year-round average was considered the criterion measure of the “true” habitual physical activity. Data were analyzed separately by CD and RD. At least 5 CD or 6 RD were necessary to achieve an ICC of .80. A minimum of 30 CD or 14 RD were necessary to achieve an MAPE lower than 10%. These findings provide researchers and practitioners with useful information to determine appropriate measurement length and the method of data selection based on a desired level of reliability and validity.