Pinching instabilities in superconducting strings

Superconducting cosmic strings can exhibit longitudinal, pinching instabilities in some regions of the parameter space. We make predictions about the onset of this instability using the thin string approximation (TSA) and develop an improved analysis that remains applicable for small wavelength perturbations, where the TSA breaks down. We use simulations of perturbed strings to assess the accuracy of the TSA, test the predictions of our new analysis and demonstrate an improvement over previous methods in the literature. Notably, it appears that the instabilities are typically present for a larger range of magnetic strings than previously expected, and we show examples of pinching instabilities also occurring in electric strings. However, both our simulations and predictions agree that strings near the chiral limit are free from pinching instabilities and in particular our results support our previously published claim that vortons can be stable to all classical perturbations if they are sufficiently large.Comment: 14 pages, 7 figure

Annealing of defects in Fe after MeV Heavy ion irradiation

We report study of recovery dynamics, followed by in-situ resistivity measurement after 100 MeV oxygen ion irradiation, in cold rolled Fe at 300K. Scaling behavior with microstructural density and temperature of sample have been used to establish stress induced defects formed during irradiation as a new type of sink. The dynamics after irradiation has been shown to be due to migration of defects to two types of sinks i.e. stress induced defect as variable sinks and internal surfaces as fixed sinks. Experimental data obtained under various experimental conditions have been fitted to theoretical curves. Parameters thus obtained from fitting are employed to establish effect of electronic energy loss and temperature on recovery dynamics and stress associated with variable sinks.Comment: 12 pages, 7 figures. Europhysics Letter (in press

Suppressor of cytokine signalling protein SOCS3 expression is increased at sites of acute and chronic inflammation.

Treatment of cells with cytokines and growth factors leads to the synthesis of Suppressor of Cytokine Signalling (SOCS) proteins that act as potent negative regulators of signalling via the Jak/STAT pathway. We used immunohistochemistry to identify cells and pathologies where SOCS3 expression might influence acute and chronic inflammatory responses in human tissues. Epitope and GFP tagged SOCS3 fusion proteins were localised predominantly in the nucleus of transfected cells and a validated anti SOCS3 antiserum revealed the expression of SOCS3 in the nucleus and cytoplasm of macrophages, endothelial and epithelial cells in a wide range of normal tissues in tissue microarrays (n = 31 different tissues). Nuclear SOCS3 was only seen in cells expressing a high level of the protein. Comparative immunostaining of acute, chronically and granulomatously inflamed human tissues revealed higher levels of nuclear and cytoplasmic SOCS3 expression in inflamed than in corresponding normal tissues, particularly in recruited leukocyte populations, but also in epithelia. The staining appeared more intense, suggesting higher expression levels, in areas where inflammation was more acute, consistent with the time course of SOCS3 induction described in vitro. Expression of SOCS3 protein by leucocytes and other cell types in tissue sections could be a useful marker of cells undergoing acute or chronic stimulation by cytokines in vivo

Characterization of Early Cortical Neural Network Development in Multiwell Microelectrode Array Plates.

We examined neural network ontogeny using microelectrode array (MEA) recordings made in multiwell MEA (mwMEA) plates over the first 12 days in vitro (DIV). In primary cortical cultures, action potential spiking activity developed rapidly between DIV 5 and 12. Spiking was sporadic and unorganized at early DIV, and became progressively more organized with time, with bursting parameters, synchrony, and network bursting increasing between DIV 5 and 12. We selected 12 features to describe network activity; principal components analysis using these features demonstrated segregation of data by age at both the well and plate levels. Using random forest classifiers and support vector machines, we demonstrated that four features (coefficient of variation [CV] of within-burst interspike interval, CV of interburst interval, network spike rate, and burst rate) could predict the age of each well recording with >65% accuracy. When restricting the classification to a binary decision, accuracy improved to as high as 95%. Further, we present a novel resampling approach to determine the number of wells needed for comparing different treatments. Overall, these results demonstrate that network development on mwMEA plates is similar to development in single-well MEAs. The increased throughput of mwMEAs will facilitate screening drugs, chemicals, or disease states for effects on neurodevelopment.EC was supported by a Wellcome Trust PhD studentship and NIHR Cambridge Biomedical Research Centre studentship. DH was supported by student services contract #EP-13-D-000108 and by a travelling fellowship from the Company of Biologists.This is the final version of the article. It first appeared from SAGE Publications via https://doi.org/10.1177/108705711664052

Melting as a String-Mediated Phase Transition

We present a theory of the melting of elemental solids as a dislocation-mediated phase transition. We model dislocations near melt as non-interacting closed strings on a lattice. In this framework we derive simple expressions for the melting temperature and latent heat of fusion that depend on the dislocation density at melt. We use experimental data for more than half the elements in the Periodic Table to determine the dislocation density from both relations. Melting temperatures yield a dislocation density of (0.61\pm 0.20) b^{-2}, in good agreement with the density obtained from latent heats, (0.66\pm 0.11) b^{-2}, where b is the length of the smallest perfect-dislocation Burgers vector. Melting corresponds to the situation where, on average, half of the atoms are within a dislocation core.Comment: 18 pages, LaTeX, 3 eps figures, to appear in Phys. Rev.

Crystalline Order on a Sphere and the Generalized Thomson Problem

We attack generalized Thomson problems with a continuum formalism which exploits a universal long range interaction between defects depending on the Young modulus of the underlying lattice. Our predictions for the ground state energy agree with simulations of long range power law interactions of the form 1/r^{gamma} (0 < gamma < 2) to four significant digits. The regime of grain boundaries is studied in the context of tilted crystalline order and the generality of our approach is illustrated with new results for square tilings on the sphere.Comment: 4 pages, 5 eps figures Fig. 2 revised, improved Fig. 3, reference typo fixe

Contemporary medical television and crisis in the NHS

This article maps the terrain of contemporary UK medical television, paying particular attention to Call the Midwife as its centrepiece, and situating it in contextual relation to the current crisis in the NHS. It provides a historical overview of UK and US medical television, illustrating how medical television today has been shaped by noteworthy antecedents. It argues that crisis rhetoric surrounding healthcare leading up to the passing of the Health and Social Care Act 2012 has been accompanied by a renaissance in medical television. And that issues, strands and clusters have emerged in forms, registers and modes with noticeable regularity, especially around the value of affective labour, the cultural politics of nostalgia and the neoliberalisation of healthcare