Context. The strong damping of kink oscillations of coronal loops can be explained by mode coupling. The damping envelope depends on the transverse density profile of the loop. Observational measurements of the damping envelope have been used to determine the transverse loop structure which is important for understanding other physical processes such as heating. Aims. The general damping envelope describing the mode coupling of kink waves consists of a Gaussian damping regime followed by an exponential damping regime. Recent observational detection of these damping regimes has been employed as a seismological tool. We extend the description of the damping behaviour to account for additional physical effects, namely a time-dependent period of oscillation, the presence of additional longitudinal harmonics, and the decayless regime of standing kink oscillations. Methods. We examine four examples of standing kink oscillations observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We use forward modelling of the loop position and investigate the dependence on the model parameters using Bayesian inference and Markov Chain Monte Carlo (MCMC) sampling. Results. Our improvements to the physical model combined with the use of Bayesian inference and MCMC produce improved estimates of model parameters and their uncertainties. Calculation of the Bayes factor also allows us to compare the suitability of different physical models. We also use a new method based on spline interpolation of the zeroes of the oscillation to accurately describe the background trend of the oscillating loop. Conclusions. This powerful and robust method allows for accurate seismology of coronal loops, in particular the transverse density profile, and potentially reveals additional physical effects.
Cache-aided small-cell network is becoming an effective method to improve the transmission rate and reduce the backhaul load. Due to the limited capacity of backhaul, less power should be allocated to users whose requested contents do not exist in the local caches to maximize the performance of caching. In this paper, power allocation is considered to improve the performance of cache-aided small-cell networks with limited backhaul, where interference alignment (IA) is utilized to manage interferences among users. Specifically, three power allocation algorithms are proposed. First, we come up with a power allocation algorithm to maximize the sum transmission rate of the network, considering the limitation of backhaul. Second, in order to have more users meet their rate requirements, a power allocation algorithm to minimizing the average outage probability is also proposed. In addition, in order to further improve the users' experience, a power allocation algorithm that maximizes the average satisfaction of all the users is also designed. Simulation results are provided to show the effectiveness of the three proposed power allocation algorithms for cache-aided small-cell networks with limited backhaul.
The recently concluded 'People of the British Isles' project (hereafter PoBI) combined large-scale, local DNA sampling with innovative data analysis to generate a survey of the genetic structure of Britain in unprecedented detail; the results were presented by Leslie and colleagues in 2015. Comparing clusters of genetic variation within Britain with DNA samples from Continental Europe, the study elucidated past immigration events via the identification and dating of historic admixture episodes (the interbreeding of two or more different population groups). Among its results, the study found "no clear genetic evidence of the Danish Viking occupation and control of a large part of England, either in separate UK clusters in that region, or in estimated ancestry profiles", therefore positing "a relatively limited input of DNA from the Danish Vikings", with 'Danish Vikings' defined in the study, and thus in this article, as peoples migrating from Denmark to eastern England in the late ninth and early tenth centuries (Leslie et al.2015: 313). Here, we consider the details of certain assumptions that were made in the study, and offer an alternative interpretation to the above conclusion. We also comment on the substantial archaeological and linguistic evidence for a large-scale Danish Viking presence in England.
We present the magnetic and thermal properties of the bosonic-superfluid phase in a spin-dimer network using both quasistatic and rapidly changing pulsed magnetic fields. The entropy derived from a heat-capacity study reveals that the pulsed-field measurements are strongly adiabatic in nature and are responsible for the onset of a significant magnetocaloric effect (MCE). In contrast to previous predictions we show that the MCE is not just confined to the critical regions, but occurs for all fields greater than zero at sufficiently low temperatures. We explain the MCE using a model of the thermal occupation of exchange-coupled dimer spin states and highlight that failure to take this effect into account inevitably leads to incorrect interpretations of experimental results. In addition, the heat capacity in our material is suggestive of an extraordinary contribution from zero-point fluctuations and appears to indicate universal behavior with different critical exponents at the two field-induced critical points. The data at the upper critical point, combined with the layered structure of the system, are consistent with a two-dimensional nature of spin excitations in the system.
MHz conductivity, torque magnetometer and magnetization measurements are reported on single crystals of CeOs4Sb12 and NdOs4Sb12 using temperatures down to 0.5 K and magnetic fields of up to 60 tesla. The field-orientation dependence of the de Haas-van Alphen and Shubnikov-de Haas oscillations is deduced by rotating the samples about the  and [0¯11] directions. The results indicate that NdOs4Sb12 has a similar Fermi surface topology to that of the unusual superconductor PrOs4Sb12, but with significantly smaller effective masses, supporting the importance of local phonon modes in contributing to the low-temperature heat capacity of NdOs4Sb12. By contrast, CeOs4Sb12 undergoes a field-induced transition from an unusual semimetal into a high-field, hightemperature state characterized by a single, almost spherical Fermi-surface section. The behavior of the phase boundary and comparisons with models of the bandstructure lead us to propose that the field-induced phase transition in CeOs4Sb12 is similar in origin to the well-known α − γ transition in Ce and its alloys.
Recent years have seen a dramatic increase in interest in the use of ring-opening polymerization of N-carboxyanhydride monomers as a method to prepare well-defined polypeptides and peptide hybrid materials. The resulting molecules are often capable of assembling into a variety of different structures, including micelles, vesicles, nanoparticles and hydrogels, and therefore have been explored as novel drug delivery systems. Peptides are attractive in this regard due to their rich chemical functionality and ability to assemble through the formation of secondary structures (e.g. α-helices and β-sheets). In addition, they are inherently biodegradable and biocompatible. This review describes recent advances in the field, covering aspects such as improved methods with which to prepare better-defined polypeptides, crosslinking of assemblies to enhance biostability, the preparation of materials that respond to a variety of stimuli (including light and intra- or extracellular redox conditions), functionalization with targeting ligands to enhance cellular uptake, assemblies for small interfering RNA delivery and approaches to theranostic systems. © 2014 Society of Chemical Industry
Prediction of self-harm is limited clinically. Early identification of individuals likely to repeat self-harm could improve outcomes and reduce suicide risk. Various neurocognitive deficits have been found in people who self-harm, but the ability of these to predict repetition has yet to be established
Identify neurocognitive factors that may predict repetition of self-harm.
Systematic narrative review of English language publications assessing neurocognitive functioning and self-harm repetition, searching multiple databases from inception to March 2015. Quality of studies was appraised. A narrative synthesis was performed.
7026 unique records were identified, and 169 full-texts assessed. 15 unique studies provided data. No imaging studies could be included. Most studies assessed cognitive control or problem solving, but neither factor was consistently associated with repetition. However, specific tasks may show promise. Two studies in adolescents suggest that value-based decision-making impairments could be predictive of repetition. There were too few results for memory to draw specific conclusions.
Selected studies suggest promise for particular neurocognitive factors and specific cognitive tasks in terms of repetition of self-harm.
In this comprehensive review, we report on the preparation of graft-copolymers of cellulose and cellulose derivatives using atom transfer radical polymerization (ATRP) under homogeneous conditions. The review is divided into four sections according to the cellulosic material that is graft-copolymerised; (i) cellulose, (ii) ethyl cellulose, (iii) hydroxypropyl cellulose and (iv) other cellulose derivatives. In each section, the grafted synthetic polymers are described as well as the methods used for ATRP macro-initiator formation and graft-copolymerisation. The physical properties of the graft-copolymers including their self-assembly in solution into nanostructures and their stimuli responsive behaviour are described. Potential applications of the self-assembled graft copolymers in areas such as nanocontainers for drug delivery are outlined.
Highly porous polymers (polyHIPEs) have been prepared by the photopolymerization of high internal phase emulsions (HIPEs) with varying ratios of thiol and acrylate monomers. The resulting polymers have a nominal porosity of 80%, and are seen to have a well-defined, interconnected pore morphology, with average pore diameters ranging from 30 to 60 μm. The polyHIPE polymers have been shown using a colourimetric (Ellman's) assay to contain residual thiols which are reactive towards a range of (meth)acrylates (hexafluoroisopropyl acrylate, fluorescein O-acrylate and poly(ethylene glycol) methyl ether methacrylate). Functionalization was explored using thermally- and UV-initiated radical-mediated "click" reactions and an amine-catalysed Michael addition reaction. The extent of functionalization was investigated qualitatively and quantitatively using a range of techniques (solid state NMR spectroscopy; FTIR spectroscopy; X-ray photoelectron spectroscopy (XPS); observation of fluorescence); high levels of conversion (up to 90–95%) were observed for the thermally-initiated radical reaction and the Michael reaction.