A new behavioural model for performance evaluation of common mode chokes

A galvanically isolated three-phase AC/AC converter with a high-frequency AC-link has been analyzed from an EMC point of view. This is a special configuration because of a large number of switches, a high frequency transformer, and a fourwire output. The essential coupling paths are identified. Corresponding suppression remedies are given. The results, before and after measures, have been presented to demonstrate the improvement in EMC. Keywords: AC/AC converter; electromagnetic interference; galvanically isolate

Performance optimization aspects of common mode chokes

Optimization aspects of common mode chokes are presented. These are based on a behavioral model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit

Model comportemental pour l`evaluation des performances de chokes de mode commun

Un model comportemental pour l’évaluation des performances de choke de mode commun (CMC) est proposé : la topologie et les méthodes utilisés pour modéliser les différentes propriétés de la CMC sont décrites. Il s’agit de la combinaison d’une modélisation précise de la perméabilité complexe du matériau, de la saturation, des inductances de fuite et des capacités parasites. Les données necessaries fournies par le designer sont les valeurs de courants, tensions et impédances du système actuel sans CMC et des paramètres disponibles dans la littérature et /ou des manufacturiers en ce qui concerne la CMC modélisée. Ce model comportemental s’avère essentiel dans la simulation des effets des interférences électromagnétiques (EMI)

Upper extremity function and activity in facioscapulohumeral dystrophy and limb-girdle muscular dystrophies:A systematic review

Purpose: The aims of this review were (1) to provide insight into the natural course of upper-extremity (UE) impairments and UE activity limitations associated with facioscapulohumeral dystrophy (FSHD) and limb-girdle muscular dystrophies (LGMD), and (2) to provide an overview of outcome measures used to evaluate UE function and activity in patients with FSHD and LGMD. Methods: Scientific literature databases (PubMed, MEDLINE, EMBASE, CINAHL and Cochrane) were searched for relevant publications. Inclusion criteria: (1) studies that included persons with a diagnosis of FSHD or LGMD; and (2) studies that reported the natural course of the UE functions and/or activity with outcome measures at these levels. Results: 247 publications were screened, of which 16 fulfilled the selection criteria. Most studies used manual muscle testing (MMT) to evaluate UE function and the Brooke Scale to evaluate UE mobility activities. The clinical picture of UE impairments and limitations of UE activities in FSHD and LGMD patients was highly variable. In general, FSHD and LGMD patients experience difficulty elevating their upper extremities and the execution of tasks takes considerably longer time. Conclusions: The clinical course of UE impairments and activity limitations associated with FSHD and LGMD is difficult to predict due to its high variability. Although measures like MMT and the Brooke Scale are often used, there is a lack of more specific outcome measures to assess UE function and UE capacity and performance in daily life. Measures such as 3D motion analysis and electromyography (EMG) recordings are recommended to provide additional insight in UE function. Questionnaires like the Abilhand are recommended to assess UE capacity and accelerometry to assess UE performance in daily life.Implications for RehabilitationThere is a need for specific outcome measures on the level of UE activity.Both the level of capacity and performance should be assessed.Possible outcome measures include 3D motion analysis to assess UE function, questionnaires like the Abilhand to assess UE capacity and accelerometry to assess performance of UE activities in daily life

Patterns of decline in upper limb function of boys and men with DMD:An international survey

With increasing life expectancy, upper extremity (UE) function becomes more and more important in boys with Duchenne muscular dystrophy (DMD). Knowledge of UE function in these children is, however, limited. The aim of this study was to gain insight into the changing patterns of UE function during the course of DMD. A Web-based questionnaire on UE function, covering all domains of the International Classification of Functioning Disability and Health, was distributed worldwide. Primary domains of the questionnaire were: participant characteristics, UE pain and stiffness, UE activities, and social participation. Data were described per disease stage and analyzed using descriptive analysis. A total of 213 boys/men with DMD (1-35 years) were included in this study. UE pain, stiffness, and activity limitations increased with disease stage. UE activity limitations already occurred in the early ambulatory stage. Compared to the healthy population, social participation was restricted in DMD patients and about 70 % of the respondents experienced UE limitations when performing social activities. Despite the existence of UE impairments, only 9 % of the respondents used supportive aids. Functional capacities and activities of the UE are limited already in the early ambulatory stage of patients with DMD affecting their social participation. Therefore, clinicians should pay attention to UE limitations before DMD patients lose their capacity to walk. Effective and adequate aids as well as attention for pain and stiffness in the therapeutic management could help to reduce UE activity limitations and related restrictions in social participation

Readiness-based differentiation in primary school mathematics: expert recommendations and teacher self-assessment

The diversity of students’ achievement levels within classrooms has made it essential for teachers to adapt their lessons to the varying educational needs of their students (‘differentiation’). However, the term differentiation has been interpreted in diverse ways and there is a need to specify what effective differentiation entails. Previous reports of low to moderate application of differentiation underscore the importance of practical guidelines for implementing differentiation. In two studies, we investigated how teachers should differentiate according to experts, as well as the degree to which teachers already apply the recommended strategies. Study 1 employed the Delphi technique and focus group discussions to achieve consensus among eleven mathematics experts regarding a feasible model for differentiation in primary mathematics. The experts agreed on a five-step cycle of differentiation: (1) identification of educational needs, (2) differentiated goals, (3) differentiated instruction, (4) differentiated practice, and (5) evaluation of progress and process. For each step, strategies were specified. In Study 2, the Differentiation Self-Assessment Questionnaire (DSAQ) was developed to investigate how teachers  self-assess their use of the strategies recommended by the experts. While teachers (N = 268) were moderately positive about their application of the strategies overall, we also identified areas of relatively low usage (including differentiation for high-achieving students) which require attention in teacher professional development. Together, these two studies provide a model and strategies for differentiation in primary mathematics based on expert consensus, the DSAQ which can be employed in future studies, and insights into teachers’ self-assessed application of specific aspects of differentiation

The Mindful Attention Awareness Scale for Adolescents (MAAS-A): Psychometric Properties in a Dutch Sample

The factor structure and psychometric properties of the Dutch version of the Mindful Attention Awareness Scale for Adolescents (MAAS-A) was studied in a sample of adolescents (n = 717; age range, 11–17 years) of the general population. The MAAS-A and other questionnaires measuring other constructs were administered in high schools across the Netherlands. A one-factor structure was demonstrated using principal component analysis and was further confirmed using confirmatory factor analysis. The MAAS-A was shown to have high internal consistency. Expected negative correlations between mindfulness and self-reported stress and emotion regulation strategies such as rumination and catastrophizing were found. Further, mindfulness was positively correlated with happiness, healthy self-regulation, and with another recently developed measure of mindfulness in children and adolescents, the Child and Adolescent Mindfulness Measure. Mindfulness as measured by the MAAS-A correlated positively with quality of life, but an expected positive relationship with acceptance was not found. Interestingly, adolescents without meditation experience scored higher on the MAAS-A than adolescents without this experience. Further, adolescents with chronic disorders scored lower on the MAAS-A than adolescents without these disorders. Overall, this study has shown evidence of the first valid and reliable Dutch measure of mindfulness for adolescents. The factor structure, internal consistency, and convergent and divergent validity as well as their relationship to quality of life are comparable to the original MAAS-A