Design challenges in the use of silicon carbide JFETs in matrix converter applications

This paper investigates some of the challenges en¬countered during the implementation of a Silicon Carbide JFET matrix converter which has been designed to meet a specific power density of 20kW/litre with forced air cooling. After a brief introduction to the main features of the hardware implementation of the power converter, an insight into the control strategy and controller platform adopted is given with a particular attention to the issues relating to the high switching frequencies on the controller requirements and the performance implications of the gate drive circuitry. An analysis of the results which show the effects of gate driver and controller induced commutation time limitations on the output waveform quality is presented. Wide bandgap semiconductor devices offer the power electronic engineer new opportunities for high speed, high efficiency designs but these devices cannot be used as a simple like for like replacements and as such the whole converter system needs to be looked at

Lexical organization in deaf children who use British Sign Language: Evidence from a semantic fluency task

We adapted the semantic fluency task into British Sign Language (BSL). In Study 1, we present data from twenty-two deaf signers aged four to fifteen. We show that the same ‘cognitive signatures’ that characterize this task in spoken languages are also present in deaf children, for example, the semantic clustering of responses. In Study 2, we present data from thirteen deaf children with Specific Language Impairment (SLI) in BSL, in comparison to a subset of children from Study 1 matched for age and BSL exposure. The two groups' results were comparable in most respects. However, the group with SLI made occasional word-finding errors and gave fewer responses in the first 15 seconds. We conclude that deaf children with SLI do not differ from their controls in terms of the semantic organization of the BSL lexicon, but that they access signs less efficiently

Operationalization and measurement of sign language

This piece will be included in a collection of commentaries that are being compiled as a Letter to the Editor

Lessons to be Learned from Bimodal Bilingualism

This article presents a selective overview of topics related to the language experience of early bimodal bilinguals - individuals who are raised from an early age using two languages from two different modalities, typically spoken (or written) and signed. We show that deaf and hearing bimodal bilinguals may display patterns of bilingualism that are similar to unimodal bilinguals in some ways, such as the use of both languages in a single situation or even a single utterance. Nevertheless, there are also differences between bimodal and unimodal bilinguals, and differences among different subgroups of bimodal bilinguals, given large variation in relative access to the dominant and minority language(s) in their environment and their differential experiences in schooling and interactions with potential interlocutors. Moreover, we review studies discussing potential advantages of the sign modality and advantages of bilingualism in this population. We hope to highlight the importance of considering children’s overall language experience, including the age(s) at which they are exposed to each of their languages, the richness of their experiences with each of the languages, and the ways that the language-learning experience may contribute to the child’s linguistic and cognitive development

Applying complexity science to air traffic management

Complexity science is the multidisciplinary study of complex systems. Its marked network orientation lends itself well to transport contexts. Key features of complexity science are introduced and defined, with a specific focus on the application to air traffic management. An overview of complex network theory is presented, with examples of its corresponding metrics and multiple scales. Complexity science is starting to make important contributions to performance assessment and system design: selected, applied air traffic management case studies are explored. The important contexts of uncertainty, resilience and emergent behaviour are discussed, with future research priorities summarised

Interpretable support vector machines for functional data

Support Vector Machines (SVMs) is known to be a powerful nonparametric classification technique even for high-dimensional data. Although predictive ability is important, obtaining an easy-to-interpret classifier is also crucial in many applications. Linear SVM provides a classifier based on a linear score. In the case of functional data, the coefficient function that defines such linear score usually has many irregular oscillations, making it difficult to interpret. This paper presents a new method, called Interpretable Support Vector Machines for Functional Data, that provides an interpretable classifier with high predictive power. Interpretability might be understood in different ways. The proposed method is flexible enough to cope with different notions of interpretability chosen by the user, thus the obtained coefficient function can be sparse, linear-wise, smooth, etc. The usefulness of the proposed method is shown in real applications getting interpretable classifiers with comparable, sometimes better, predictive ability versus classical SVM.The authors thank the anonymous referees and the associate editor for their helpful comments to improve the article. This work has been partially supported by projects MTM2009-14039, ECO2011-25706 of Ministerio de Ciencia e Innovación and FQM-329 of Junta de Andalucía, Spain

Does dysfunction of the mirror neuron system contribute to symptoms in amyotrophic lateral sclerosis?

There is growing evidence that mirror neurons, initially discovered over two decades ago in the monkey, are present in the human brain. In the monkey, mirror neurons characteristically fire not only when it is performing an action, such as grasping an object, but also when observing a similar action performed by another agent (human or monkey). In this review we discuss the origin, cortical distribution and possible functions of mirror neurons as a background to exploring their potential relevance in amyotrophic lateral sclerosis (ALS). We have recently proposed that ALS (and the related condition of frontotemporal dementia) may be viewed as a failure of interlinked functional complexes having their origins in key evolutionary adaptations. This can include loss of the direct projections from the corticospinal tract, and this is at least part of the explanation for impaired motor control in ALS. Since, in the monkey, corticospinal neurons also show mirror properties, ALS in humans might also affect the mirror neuron system. We speculate that a defective mirror neuron system might contribute to other ALS deficits affecting motor imagery, gesture, language and empathy