Crystallization during emplacement of lava flows

Thermal models of lava flows provide a way of estimating emplacement durations and eruption rates of planetary lava flows, which can help constrain magma ascent, rheology and composition. Most of the models that have been developed consider only the effects of cooling by radiation. However, heating due to crystallization can be a large component of the overall heat budget of a flow. Little is known about the amount of crystallization and latent heating during flow advance. Crystal size distribution (CSD) measurements were made to quantify and study the effects of crystallization in the 1984 Mauna Loa flow. For flows on Mars, we must assume that the amount of crystallization is similar to that in terrestrial flows and place minimum and maximum bounds on the latent heat effect. Unfortunately, as examples given here show, there can be anywhere from 0 to 60 percent crystallization during flow advance. To improve constraints for Martian flows, we need to search for correlations in terrestrial flows between flow morphology and the amount of crystallization during emplacement

Teaching and learning guide for: Imagined intergroup contact: Theory, paradigm, and practice

A goal shared enthusiastically amongst many social psychologists is the improvement of intergroup relations. Conflict between groups is usually related to distinct, and in many cases opposing, identities, based on (for example) ethnicity, nationality, and religion, but also gender, age, sexual orientation and political or individual preferences. Our research has developed a new intervention for improving intergroup relations based on an integration of theory and empirical work on social cognition and intergroup relations. We've called the technique Imagined Contact because it is based on the mental simulation of intergroup contact experiences. Collectively, our research has focused on refining and evaluating imagined contact as an effective tool for the enhancement of intergroup relations. Our article in Social and Personality Psychology Compass provides a summary of the basic theory underlying imagined contact, a review of empirical findings to date, and a framework for developing practical applications of the intervention (in particular as a school-based intervention). We wanted to offer a teaching and learning guide for this article because we believe that the imagined contact task provides a flexible, effective, and easy-to-use tool for teachers, seminar leaders, students, and practitioners. The task can be used as a basis for encouraging more positive and open attitudes towards other groups, a way of preparing people for future intergroup encounters, a stimulus for discussions about the value in experiencing social diversity, and a way of illustrating the power of mental processes in forming and challenging attitudes about others

The Inhomogeneous Hall's Ray

We show that the inhomogenous approximation spectrum, associated to an irrational number \alpha\ always has a Hall's Ray; that is, there is an \epsilon>0 such that [0,\epsilon) is a subset of the spectrum. In the case when \alpha\ has unbounded partial quotients we show that the spectrum is just a ray.Comment: Fixed typos in bibliograph

Intersection of three-dimensional geometric surfaces

Calculating the line of intersection between two three-dimensional objects and using the information to generate a third object is a key element in a geometry development system. Techniques are presented for the generation of three-dimensional objects, the calculation of a line of intersection between two objects, and the construction of a resultant third object. The objects are closed surfaces consisting of adjacent bicubic parametric patches using Bezier basis functions. The intersection determination involves subdividing the patches that make up the objects until they are approximately planar and then calculating the intersection between planes. The resulting straight-line segments are connected to form the curve of intersection. The polygons in the neighborhood of the intersection are reconstructed and put back into the Bezier representation. A third object can be generated using various combinations of the original two. Several examples are presented. Special cases and problems were encountered, and the method for handling them is discussed. The special cases and problems included intersection of patch edges, gaps between adjacent patches because of unequal subdivision, holes, or islands within patches, and computer round-off error

Glycine receptor autoantibodies disrupt inhibitory neurotransmission

Chloride-permeable glycine receptors have an important role in fast inhibitory neurotransmission in the spinal cord and brainstem. Human immunoglobulin G (IgG) autoantibodies to glycine receptors are found in a substantial proportion of patients with progressive encephalomyelitis with rigidity and myoclonus, and less frequently in other variants of stiff person syndrome. Demonstrating a pathogenic role of glycine receptor autoantibodies would help justify the use of immunomodulatory therapies and provide insight into the mechanisms involved. Here purified IgGs from four patients with progressive encephalomyelitis with rigidity and myoclonus or stiff person syndrome and glycine receptor autoantibodies were observed to profoundly disrupt glycinergic neurotransmission. In whole cell patch clamp recordings from cultured rat spinal motoneurons, glycinergic synaptic currents were almost completely abolished following incubation in patient IgGs. Most human autoantibodies targeting other CNS neurotransmitter receptors, such as N-methyl-D-aspartate (NMDA) receptors, affect whole cell currents only after several hours’ incubation and this effect has been shown to be the result of antibody-mediated crosslinking and internalisation of receptors. By contrast, we observed substantial reductions in glycinergic currents with all four patient IgG preparations with 15 minutes of exposure to patient IgGs. Moreover, monovalent Fab fragments generated from the purified IgG of three of the four patients also profoundly reduced glycinergic currents compared with control Fab-IgG. We conclude that human glycine receptor autoantibodies disrupt glycinergic neurotransmission, and also suggest that the pathogenic mechanisms include direct antagonistic actions on glycine receptors.SJC is supported by from the Wellcome Trust (101696/Z/13/Z), the National Institute for Health Research (NIHR), BMA Foundation for Medical Research (Vera Down Award 2017) and the National Organisation for Rare Disorders (16006). CLD is supported by the Wellcome Trust. SRI is supported by the Wellcome Trust (104079/Z/14/Z), BMA Research Grants- Vera Down grant (2013) and Margaret Temple (2017), and by Epilepsy Research UK (P1201). The research was supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC; The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health). LJ, MIL and AV received support from the Nuffield Department of Clinical Neurosciences. DMK is supported by the Wellcome Trust, Medical Research Council and Epilepsy Research UK

“Transports of delight”? Reviews of Clarinet Performance in Paris and London, c. 1770 – c. 1810

Reviews of clarinet performance in Paris and London, c. 1770 – c. 1810 make specific reference to 18th-century performance ideals, as identified by the contemporary writer Charles Burney who described the “principal excellencies of perfect execution”. The performance qualities described by Burney and their inclusion in contemporary reports is particularly valuable in assessing performances featuring the newest woodwind instrument, the clarinet. References to many of these performance qualities combine to form detailed accounts of the sonorities, technical execution and expressive qualities evident in performances given by clarinet players in Paris and London. This article draws upon a wide selection of audience reviews of clarinet players in performance in these two centres, c.1770 – c.1810, offering revealing insights into audience perceptions of both the instrument and clarinet players. The examination of reviews of clarinet performance published in Paris and London highlight a number of specific performance themes. These are identified and discussed in this article, creating a detailed picture of 18th-century audience responses to the newest woodwind instrument and early exponents of the clarinet in each centre