Uncovering the spin ordering in magic-angle graphene via edge state equilibration

Determining the symmetry breaking order of correlated quantum phases is essential for understanding the microscopic interactions in their host systems. The flat bands in magic angle twisted bilayer graphene (MATBG) provide an especially rich arena to investigate such interaction-driven ground states, and while progress has been made in identifying the correlated insulators and their excitations at commensurate moire filling factors, the spin-valley polarizations of the topological states that emerge at high magnetic field remain unknown. Here we introduce a new technique based on twist-decoupled van der Waals layers that enables measurements of their electronic band structure and, by studying the backscattering between counter-propagating edge states, determination of relative spin polarization of the their edge modes. Applying this method to twist-decoupled MATBG and monolayer graphene, we find that the broken-symmetry quantum Hall states that extend from the charge neutrality point in MATBG are spin-unpolarized at even integer filling factors. The measurements also indicate that the correlated Chern insulator emerging from half filling of the flat valence band is spin-unpolarized, but suggest that its conduction band counterpart may be spin-polarized. Our results constrain models of spin-valley ordering in MATBG and establish a versatile approach to study the electronic properties of van der Waals systems

Art, authenticity and citizenship for people living with dementia in a care home

This paper reports on a study which examined the notions of authenticity and citizenship for people living with cognitive impairment or dementia in a care home in the North-East of England. We demonstrated that both notions were present and were encouraged by engagement with an artist, where this involved audio and visual recordings and the creation of a film. The artist's interactions were observed by a non-participant observer using ethnographic techniques, including interviews with the residents, their families and the staff of the care home. The data were analysed using grounded theory and the constant comparative method of qualitative analysis. Our findings suggest that participatory art might help to maintain and encourage authenticity and citizenship in people living with dementia in a care home. Certainly, authenticity and citizenship are notions worth pursuing in the context of dementia generally, but especially in care homes

Homeward bound or bound for a home? Assessing the capacity of dementia patients to make decisions about hospital discharge: Comparing practice with legal standards

Background This article stems from a larger project which considers ways of improving assessments of capacity and judgements about best interests in connection with people with dementia admitted to acute hospitals with respect to decisions about place of residence. Aims Our aim is to comment on how assessments of residence capacity are actually performed on general hospital wards compared with legal standards for the assessment of capacity set out in the Mental Capacity Act, 2005 (MCA). Method Our findings are grounded in ethnographic ward-based observations and in-depth interviews conducted in three hospital wards, in two hospitals (acute and rehabilitation), within two NHS healthcare trusts in the North of England over a period of nine months between 2008 and 2009. Twenty-nine patient cases were recruited to the study. We also draw from broader conceptions of capacity found in domestic and international legal, medical, ethical and social science literature. Results Our findings suggest that whilst professionals profess to be familiar with broad legal standards governing the assessment of capacity under the MCA, these standards are not routinely applied in practice in general hospital settings when assessing capacity to decide place of residence on discharge from hospital. We discuss whether the criteria set out in the MCA and the guidance in its Code of Practice are sufficient when assessing residence capacity, given the particular ambiguities and complexities of this capacity. Conclusions We conclude by suggesting that more specific legal standards are required when assessing capacity in this particular context

The Definition of Mach's Principle

Two definitions of Mach's principle are proposed. Both are related to gauge theory, are universal in scope and amount to formulations of causality that take into account the relational nature of position, time, and size. One of them leads directly to general relativity and may have relevance to the problem of creating a quantum theory of gravity.Comment: To be published in Foundations of Physics as invited contribution to Peter Mittelstaedt's 80th Birthday Festschrift. 30 page

TESSA: A toolkit for rapid assessment of ecosystem services at sites of biodiversity conservation importance

Sites that are important for biodiversity conservation can also provide significant benefits (i.e. ecosystem services) to people. Decision-makers need to know how change to a site, whether development or restoration, would affect the delivery of services and the distribution of any benefits among stakeholders. However, there are relatively few empirical studies that present this information. One reason is the lack of appropriate methods and tools for ecosystem service assessment that do not require substantial resources or specialist technical knowledge, or rely heavily upon existing data. Here we address this gap by describing the Toolkit for Ecosystem Service Site-based Assessment (TESSA). It guides local non-specialists through a selection of relatively accessible methods for identifying which ecosystem services may be important at a site, and for evaluating the magnitude of benefits that people obtain from them currently, compared with those expected under alternative land-uses. The toolkit recommends use of existing data where appropriate and places emphasis on enabling users to collect new field data at relatively low cost and effort. By using TESSA, the users could also gain valuable information about the alternative land-uses; and data collected in the field could be incorporated into regular monitoring programmes

Flow and retreat of the Late Quaternary Pine Island-Thwaites palaeo-ice stream, West Antarctica

Multibeam swath bathymetry and sub-bottom profiler data are used to establish constraints on the flow and retreat history of a major palaeo-ice stream that carried the combined discharge from the parts of the West Antarctic Ice Sheet now occupied by the Pine Island and Thwaites glacier basins. Sets of highly elongated bedforms show that, at the last glacial maximum, the route of the Pine Island-Thwaites palaeo-ice stream arced north-northeast following a prominent cross-shelf trough. In this area, the grounding line advanced to within similar to 68 km of, and probably reached, the shelf edge. Minimum ice thickness is estimated at 715 m on the outer shelf, and we estimate a minimum ice discharge of similar to 108 km(3) yr(-1) assuming velocities similar to today's Pine Island glacier (similar to 2.5 km yr(-1)). Additional bed forms observed in a trough northwest of Pine Island Bay likely formed via diachronous ice flows across the outer shelf and demonstrate switching ice stream behavior. The "style" of ice retreat is also evident in five grounding zone wedges, which suggest episodic deglaciation characterized by halts in grounding line migration up-trough. Stillstands occurred in association with changes in ice bed gradient, and phases of inferred rapid retreat correlate to higher bed slopes, supporting theoretical studies that show bed geometry as a control on ice margin recession. However, estimates that individual wedges could have formed within several centuries still imply a relatively rapid overall retreat. Our findings show that the ice stream channeled a substantial fraction of West Antarctica's discharge in the past, just as the Pine Island and Thwaites glaciers do today