Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications

Journal of Zhejiang University-SCIENCE B - In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and...     

Identifying Aberrant Data in Structural Equation Models With IRLS-ADF

In structural equation models, outliers could result in inaccurate parameter estimates and misleading fit statistics when using traditional methods. To robustly estimate structural equation models, iteratively reweighted least squares (IRLS; Yuan & Bentler, 2000) has been proposed, but not thoroughly examined. We explore the large-sample properties of IRLS and its effect on parameter recovery, model fit, and aberrant data identification. A parametric bootstrap technique is proposed to determine the tuning parameters of IRLS, which results in improved Type I error rates in aberrant data identification, for data sets generated from homogenous populations. Scenarios concerning (a) simulated data, (b) contaminated data, and (c) a real data set are studied. Results indicate good parameter recovery, model fit, and aberrant data identification when noisy observations are drawn from a real data set, but lackluster parameter recovery and identification of aberrant data when the noise is parametrically structured. Practical implications and further research are discussed.     

Effects of college prestige on men's occupational status and income

This study assesses the effects of college social prestige and college selectivity on men's occupational status and income. The analyses are based on a national sample of men from the Panel Study of Income Dynamics. College selectivity, but not college social prestige, has a significant impact on middle-aged men's income in a single year. Neither college social prestige nor selectivity, however, affect further growth in middle-aged men's income. Nor do they affect men's occupational status.     

A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars

Objective

To investigate the stress distribution to the mandible, with and without impacted third molars (IM3s) at various orientations, resulting from a 2000-Newton impact force either from the anterior midline or from the body of the mandible.

Materials and methods

A 3D mandibular virtual model from a healthy dentate patient was created and the mechanical properties of the mandible were categorized to 9 levels based on the Hounsfield unit measured from computed tomography (CT) images. Von Mises stress distributions to the mandibular angle and condylar areas from static impact forces (Load I-front blow and Load II left blow) were evaluated using finite element analysis (FEA). Six groups with IM3 were included: full horizontal bony, full vertical bony, full 450 mesioangular bony, partial horizontal bony, partial vertical, and partial 450 mesioangular bony impaction, and a baseline group with no third molars.

Results

Von Mises stresses in the condyle and angle areas were higher for partially than for fully impacted third molars under both loading conditions, with partial horizontal IM3 showing the highest fracture risk. Stresses were higher on the contralateral than on the ipsilateral side. Under Load II, the angle area had the highest stress for various orientations of IM3s. The condylar region had the highest stress when IM3s were absent.

Conclusions

High-impact forces are more likely to cause condylar rather than angular fracture when IM3s are missing. The risk of mandibular fracture is higher for partially than fully impacted third molars, with the angulation of impaction having little effect on facture risk.

     

Comparison of most‐to‐least to error correction for teaching receptive labelling for two children diagnosed with autism

Prompting systems are guidelines of when to provide learners with prompts and when to fade prompts. Today, there are several prompting systems implemented to teach receptive labeling to individuals diagnosed with autism spectrum disorders and other disabilities. This study compared most‐to‐least prompting to an error correction procedure involving feedback and remedial trials for teaching two children with autism a variety of receptive labels. All teaching was implemented in a one‐to‐one instructional setting. Researchers taught each participant how to receptively identify 18 pictures; nine were taught using error correction and nine were taught using most‐to‐least. The researchers utilized an adapted alternating treatment design nested into a multiple probe design to evaluate the two procedures. Results indicated that participants were able to reach mastery criterion on 100% of skills taught using the error correction and were able to reach mastery criterion on 88.9% of skills taught using most‐to‐least. Additionally, error correction tended to require fewer trials for participants to reach mastery criterion.     

Spontaneous Leg Movements of Infants with Down Syndrome and Nondisabled Infants

Infants with Down syndrome (DS) represent a population in which new behaviors are acquired significantly more slowly than in nondisabled infants. We propose that infants' spontaneous movements hold a key to understanding the process of development—of integrating intrinsic dynamics and function. In this investigation, we compared the spontaneous leg movements of 10 infants with DS and 2 groups of nondisabled (ND) infants matched for chronological age and motor age. In contrast to common perceptions, we did not observe a significant difference in the frequency of movements between infants with DS and ND infants. But, infants with DS demonstrated significantly fewer of the most complex patterned leg movements, that is, kicking patterns. Further, the frequency with which both DS and ND infants kicked was significantly correlated with the age at which they began to walk. Biomechanical variables were identified, as well, that related to their emergent movement patterns. These data are consistent with Edelman's proposal that spontaneous movements that occur repeatedly in regions of the organism's functional work space facilitate the development of stable behavioral patterns and emphasize the role of the interaction of multiple subsystems in the emergence of new behaviors.     

Globalisation,knowledge economy and comparative education

This paper seeks to introduce this special issue by setting out what seem to be some of the major theoretical and methodological issues raised for comparative education by the increasing prominence of the discourses of the knowledge economy, which, it is argued, represent a particularly strong version of globalisation and its possible relationships to education systems, and hence an especially acute challenge to comparative education. It focuses on the possible implications of these changes for each of the three elements of ‘national education system’. In terms of the ‘national’ it discusses the nature and consequences of methodological nationalism, and emphasises the emerging pluri‐scalar nature of the governance of education. In terms of ‘education’, it argues that education is now being asked to do different things in different ways, rather than the same things in different ways. In terms of ‘system’, it is suggested that the constitution of education sectors may be in the process of changing, with a development of parallel sectors at different scales with different responsibilities. Overall, the article suggests that we may be witnessing the development of a new functional, scalar and sectoral (non zero sum) division of the labour of educational governance. Finally, it addresses the question ‘what is now to be compared’ and considers the consequences for both ‘explaining’ and ‘learning’ through comparative education.     

Local States of Emergency: The contradictions of neo-liberal governance in education in New Zealand

In the present paper, we argue that neo-liberal governance regimes are deeply contradictory and that these contradictions are increasingly evident within the education sector. Drawing on a case study of the consequences of restructuring in education in New Zealand, arguably a paradigm case of neo-liberal governance, we suggest the state is faced with a dilemma about how best to manage these tensions and contradictions within the framework of the political rationality itself. One strategy is to isolate and localise these problems in order to contain and manage the risks associated with them. We identify five variants we argue can broadly be viewed as local states of emergency.     

Toward a Conceptual Model of Mentoring Research: Integration with Self-Regulated Learning

In this article, we present a model for academic mentoring research that incorporates theory and research on self-regulated learning. Academic mentoring research has increased in recent years, and researchers have linked mentoring with positive outcomes for protégés and mentors. This research, however, has not investigated the process whereby mentoring exerts its effects. An integration of mentoring with self-regulated learning seems valuable because self-regulated learning researchers have employed methodologies to assess its dynamic nature. We review assumptions of mentoring and self-regulated learning theories, representative mentoring research studies, and methods of assessing self-regulated learning. Following presentation of the mentoring research model, suggestions are given for types of research studies to identify the operation of key processes before, during, and after mentoring interactions. We conclude with implications of this integrated perspective for theory development and educational practice.