A hierarchy of models for superconducting thin films

A hierarchy of models for type-II superconducting thin films is presented. Through appropriate asymptotic limits this hierarchy passes from the mesoscopic Ginzburg--Landau model to the London model with isolated vortices as $\delta$-function singularities to vortex-density models and finally to macroscopic critical-state models. At each stage it is found that a key nondimensional parameter is $\Lambda = \lambda^2/d L$, where $\lambda$ is the penetration depth of the magnetic field, a material parameter, and d and L are a typical thickness and lateral dimension of the film,respectively. The models simplify greatly if this parameter is large or small

A Bayesian approach to the aperture problem of 3D motion perception

We suggest a geometric-statistical approach that can be ap- plied to the 3D aperture problem of motion perception. In simulations and psychophysical experiments we study per- ceived 3D motion direction in a binocular viewing geometry by systematically varying 3D orientation of a line stimulus moving behind a circular aperture. Although motion direc- tion is inherently ambiguous perceived directions show sys- tematic trends and a Bayesian model with a prior for small depth followed by slow motion in 3D gives reasonable fits to individual data. We conclude that the visual system tries to minimize velocity in 3D but that earlier disparity processing strongly influences perceived 3D motion direction. We discuss implications for the integration of disparity and motion cues in the human visual system

The motion of superconducting vortices in thin films of varying thickness

The interaction of superconducting vortices with superconductor/vacuum interfaces is considered. A vortex is first shown to intersect such an interface normally. Various thin-film models are then formulated, corresponding to different parameter regimes. A local analysis of a vortex is performed, and a law of motion for each vortex deduced. This law of motion implies that the vortex will move to the locally thinnest part of the film, and is consistent with the vortex moving under the curvature induced by being forced to intersect the boundaries of the film normall

Meeple Centred Design: A Heuristic Toolkit for Evaluating the Accessibility of Tabletop Games

Evaluation of accessibility within a tabletop context is much more complicated than it is within a video game environment. There is a considerable amount of variation in game systems, game mechanisms, and interaction regimes. Games may be entirely verbal, or completely non-verbal. They might be real-time or turn based, or based on simultaneous actions. They can be competitive or co-operative, or shift from one to the other during a single game session. They might involve visual pattern recognition or force players to memorise game state without visual cues. They may involve touch, or smell. They might involve social deduction or betrayal. They can encompass all sensory faculties, in differing degrees. Almost all games have accessibility considerations that should be taken into account, but there is currently no comprehensive tool by which this can be done that encompasses the rich variety of tabletop gaming interaction metaphors. In this paper, the authors discuss the heuristic lens that is used by the Meeple Centred Design tabletop accessibility project. This is a tool that has been applied to one hundred and sixteen games to date, and the full results of these have been published for analysis and consideration within the wider tabletop gaming community

Strain-dependent and distinctive T-cell responses to HIV antigens following immunisation of mice with differing chimpanzee adenovirus vaccine vectors

In vivo vaccination studies are conventionally conducted in a single mouse strain with results, only reflecting responses to a single immunogenetic background. We decided to examine the immune response to an HIV transgene (gag, pol and nef fusion protein) in 3 strains of mice (CBA, C57BL/6 and BALB/c) to determine the spectrum of responses and in addition to determine whether the serotype of the adenoviral vector used (ChAd3 and ChAd63) impacted the outcome of response. Our results demonstrated that all three strains of mice responded to the transgene and that the magnitude of responses were different between the strains. The C57BL/6 strain showed the lowest range of responses compared to the other strains and, very few responses were seen to the same peptide pool in all three strains of mice. In CBA and BALB/c mice there were significant differences in IFNγ production dependent on the adenoviral vector used. Our results suggest that employing a single strain of mouse may underestimate the efficacy and efficiency of vaccine products

Molecular Events in the Cell Types of the Olfactory Epithelium during Adult Neurogenesis

BACKGROUND: Adult neurogenesis, fundamental for cellular homeostasis in the mammalian olfactory epithelium, requires major shifts in gene expression to produce mature olfactory sensory neurons (OSNs) from multipotent progenitor cells. To understand these dynamic events requires identifying not only the genes involved but also the cell types that express each gene. Only then can the interrelationships of the encoded proteins reveal the sequences of molecular events that control the plasticity of the adult olfactory epithelium. RESULTS: Of 4,057 differentially abundant mRNAs at 5 days after lesion-induced OSN replacement in adult mice, 2,334 were decreased mRNAs expressed by mature OSNs. Of the 1,723 increased mRNAs, many were expressed by cell types other than OSNs and encoded proteins involved in cell proliferation and transcriptional regulation, consistent with increased basal cell proliferation. Others encoded fatty acid metabolism and lysosomal proteins expressed by infiltrating macrophages that help scavenge debris from the apoptosis of mature OSNs. The mRNAs of immature OSNs behaved dichotomously, increasing if they supported early events in OSN differentiation (axon initiation, vesicular trafficking, cytoskeletal organization and focal adhesions) but decreasing if they supported homeostatic processes that carry over into mature OSNs (energy production, axon maintenance and protein catabolism). The complexity of shifts in gene expression responsible for converting basal cells into neurons was evident in the increased abundance of 203 transcriptional regulators expressed by basal cells and immature OSNs. CONCLUSIONS: Many of the molecular changes evoked during adult neurogenesis can now be ascribed to specific cellular events in the OSN cell lineage, thereby defining new stages in the development of these neurons. Most notably, the patterns of gene expression in immature OSNs changed in a characteristic fashion as these neurons differentiated. Initial patterns were consistent with the transition into a neuronal morphology (neuritogenesis) and later patterns with neuronal homeostasis. Overall, gene expression patterns during adult olfactory neurogenesis showed substantial similarity to those of embryonic brain

De novo SCN1A mutations in Dravet syndrome and related epileptic encephalopathies are largely of paternal origin

Background: Dravet syndrome is a severe infantile epileptic encephalopathy caused in approximately 80% of cases by mutations in the voltage gated sodium channel subunit gene SCN1A. The majority of these mutations are de novo. The parental origin of de novo mutations varies widely among genetic disorders and the aim of this study was to determine this for Dravet syndrome. Methods: 91 patients with de novo SCN1A mutations and their parents were genotyped for single nucleotide polymorphisms (SNPs) in the region surrounding their mutation. Allele specific polymerase chain reaction (PCR) based on informative SNPs was used to separately amplify and sequence the paternal and maternal alleles to determine in which parental chromosome the mutation arose. Results: The parental origin of SCN1A mutations was established in 44 patients for whom both parents were available and SNPs were informative. The mutations were of paternal origin in 33 cases and of maternal origin in the remaining 11 cases. De novo mutation of SCN1A most commonly, but not exclusively, originates from the paternal chromosome. The average age of parents originating mutations did not differ from that of the general population. Conclusions: The greater frequency of paternally derived mutations in SCN1A is likely to be due to the greater chance of mutational events during the increased number of mitoses which occur during spermatogenesis compared to oogenesis, and the greater susceptibility to mutagenesis of the methylated DNA characteristic of sperm cells.Sarah E. Heron, Ingrid E. Scheffer, Xenia Iona, Sameer M. Zuberi, Rachael Birch, Jacinta M. McMahon, Carla M. Bruce, Samuel F. Berkovic, John C. Mulle

Fusing Quantitative Requirements Analysis with Model-based Systems Engineering

A vision is presented for fusing quantitative requirements analysis with model-based systems engineering. This vision draws upon and combines emergent themes in the engineering milieu. “Requirements engineering” provides means to explicitly represent requirements (both functional and non-functional) as constraints and preferences on acceptable solutions, and emphasizes early-lifecycle review, analysis and verification of design and development plans. “Design by shopping” emphasizes revealing the space of options available from which to choose (without presuming that all selection criteria have previously been elicited), and provides means to make understandable the range of choices and their ramifications. “Model-based engineering” emphasizes the goal of utilizing a formal representation of all aspects of system design, from development through operations, and provides powerful tool suites that support the practical application of these principles. A first step prototype towards this vision is described, embodying the key capabilities. Illustrations, implications, further challenges and opportunities are outlined