Disordered Topological Insulators via C∗C^*-Algebras

The theory of almost commuting matrices can be used to quantify topological obstructions to the existence of localized Wannier functions with time-reversal symmetry in systems with time-reversal symmetry and strong spin-orbit coupling. We present a numerical procedure that calculates a Z_2 invariant using these techniques, and apply it to a model of HgTe. This numerical procedure allows us to access sizes significantly larger than procedures based on studying twisted boundary conditions. Our numerical results indicate the existence of a metallic phase in the presence of scattering between up and down spin components, while there is a sharp transition when the system decouples into two copies of the quantum Hall effect. In addition to the Z_2 invariant calculation in the case when up and down components are coupled, we also present a simple method of evaluating the integer invariant in the quantum Hall case where they are decoupled.Comment: Added detail regarding the mapping of almost commuting unitary matrices to almost commuting Hermitian matrices that form an approximate representation of the sphere. 6 pages, 6 figure

EAGLE ISS - A modular twin-channel integral-field near-IR spectrograph

The ISS (Integral-field Spectrograph System) has been designed as part of the EAGLE Phase A Instrument Study for the E-ELT. It consists of two input channels of 1.65x1.65 arcsec field-of-view, each reconfigured spatially by an image-slicing integral-field unit to feed a single near-IR spectrograph using cryogenic volume-phase-holographic (VPH) gratings to disperse the image spectrally. A 4k x 4k array detector array records the dispersed images. The optical design employs anamorphic magnification, image slicing, VPH gratings scanned with a novel cryo-mechanism and a three-lens camera. The mechanical implementation features IFU optics in Zerodur, a modular bench structure and a number of high-precision cryo-mechanisms.Comment: 12 pages, to be published in Proc SPIE 7735: Ground-based & Airborne Instrumentation for Astronomy II

Living with family: perceptions of health and subjective well-being of adults with an intellectual disability

Background: Little is known about the role of living circumstances to the perception of subjective well‐being (SWB) and health of adults with intellectual disability (ID). The aim of the present study was to examine whether living circumstances impact differently on the perception of health and SWB and whether potential differences persist after accounting for other variables (e.g. level of support needs and reporting method). Methods: Secondary data analysis was undertaken of a large national survey of adults with an ID in England, aged 16 years and over. Participants were identified as living with family (N = 1528) or living out of home (N = 874). Results: The results of t‐test and chi‐square revealed that levels of health and SWB were perceived as being higher for people living with family than those living in out‐of‐home settings. Multiple linear regression analyses fitted to explore factors associated with these reported differences revealed that, when controlling for other variables, living with family was highly associated with reports of better SWB. Multiple logistic regression revealed that whilst the health status of people living with families were perceived as better, this was only true when their support needs were low. Poorest health outcomes were found for people with highest support needs who lived with family. Conclusions: On the whole, the health and well‐being of adults living with family were perceived more positively than those living out of home. However, potential health disparities exist for those with high support needs who live with family. Further longitudinal research is needed to explore causes and potential solution to these inequalities

School‐based anti‐bullying approaches for children and young people with special educational needs and disabilities: a systematic review and synthesis

Mainstream anti-bullying interventions can reduce primary school-level victimisation by 15–16% and bullying perpetration by 19%–20% (Aggression and Violent Behavior, 2019; 45: 111–133). Less is known about anti-bullying interventions for pupils with special educational needs and disabilities (SEND) even though they are at least 2–4 times more likely to be involved in bullying. This systematic review aimed to identify reported anti-bullying approaches for pupils with SEND, what the evidence is for these approaches reducing bullying and which design factors are linked to a reduction in bullying. We searched 10 databases and four grey literature sources for articles that evaluated school-based anti-bullying strategies for children and young people aged 4–18 years with SEND. This review included 15 studies and used the Mixed Methods Appraisal Tool for quality and risk of bias. Ten reported a reduction in bullying involvement, but the evidence was variable. A further 27 articles formed a ‘suggested strategies’ review which synthesised articles without evaluations of interventions but that suggested anti-bullying strategies for use with pupils with SEND. The main suggestion was encouraging social skills and networks. Interventions should be evaluated for feasibility, acceptability and effectiveness. High-quality randomised controlled trials are required to build an evidence base to support pupils with SEND

Critical review of the impacts of grazing intensity on soil organic carbon storage and other soil quality indicators in extensively managed grasslands

Acknowledgements This work contributes to the N-Circle project (grant number BB/N013484/1), and CINAg (BB/N013468/1) Virtual Joint Centres on Agricultural Nitrogen (funded by the Newton Fund via UK BBSRC/NERC), U-GRASS (grant number NE/M016900/1), the Belmont Forum/FACCE-JPI DEVIL project (grant number NE/M021327/1), Soils-R-GGREAT (grant number NE/P019455/1), ADVENT (grant number NE/M019713/1), Sêr Cymru LCEE-NRN project, Climate-Smart Grass and the Scottish Government’s Strategic Research Programme.Peer reviewedPublisher PD

Perceptions and discourses relating to genetic testing : interviews with people with Down syndrome

Background: The perceptions of individuals with Down syndrome are conspicuously absent in discussions about the use of prenatal testing. Method: Eight individuals with Down syndrome were interviewed about their views and experience of the topic of prenatal testing. Results: Interpretative Phenomenological Analysis revealed two major themes with sub themes: 1) A devalued condition and a valued life and 2) A question of ‘want?’ Foucauldian Discourse Analysis highlighted two main discursive practices: 1) Social deviance and 2) Tragedy and catastrophe of the birth of a baby with Down syndrome. Conclusions: The findings suggest that individuals with intellectual disabilities can make a valuable contribution to discussions surrounding the use of prenatal testing. Implications for clinical practice include the use of information about Down syndrome given to prospective parents, and the possible psychological impact of prenatal testing practices on individuals with Down syndrome

Anomalies in the Entanglement Properties of the Square Lattice Heisenberg Model

We compute the bipartite entanglement properties of the spin-half square-lattice Heisenberg model by a variety of numerical techniques that include valence bond quantum Monte Carlo (QMC), stochastic series expansion QMC, high temperature series expansions and zero temperature coupling constant expansions around the Ising limit. We find that the area law is always satisfied, but in addition to the entanglement entropy per unit boundary length, there are other terms that depend logarithmically on the subregion size, arising from broken symmetry in the bulk and from the existence of corners at the boundary. We find that the numerical results are anomalous in several ways. First, the bulk term arising from broken symmetry deviates from an exact calculation that can be done for a mean-field Neel state. Second, the corner logs do not agree with the known results for non-interacting Boson modes. And, third, even the finite temperature mutual information shows an anomalous behavior as T goes to zero, suggesting that T->0 and L->infinity limits do not commute. These calculations show that entanglement entropy demonstrates a very rich behavior in d>1, which deserves further attention.Comment: 12 pages, 7 figures, 2 tables. Numerical values in Table I correcte

Topology and Phases in Fermionic Systems

There can exist topological obstructions to continuously deforming a gapped Hamiltonian for free fermions into a trivial form without closing the gap. These topological obstructions are closely related to obstructions to the existence of exponentially localized Wannier functions. We show that by taking two copies of a gapped, free fermionic system with complex conjugate Hamiltonians, it is always possible to overcome these obstructions. This allows us to write the ground state in matrix product form using Grassman-valued bond variables, and show insensitivity of the ground state density matrix to boundary conditions.Comment: 4 pages, see also arxiv:0710.329