College of occupational therapists: Position paper on the way ahead for research, education and practice in mental health

The future of occupational therapy in mental health has been a topic of reflection and debate. The Education and Research Board (now the Education and Practice Board) of the College of Occupational Therapists created a Working Group to develop a position paper on the way ahead for research, education and practice in mental health. Following consultation, the Working Group reviewed literature, examined current research and surveyed practitioners, managers and educators. From these findings, recommendations have been made which will lead to a firmer evidence base for the practice of occupational therapy in mental health, leading to a more effective use of the expertise of occupational therapists and an improved service for users

The vervet monkey (cercopithecus aethiops) as an experimental model for pulpal studies

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Recent Extreme Ultraviolet Solar Spectra and Spectroheliograms

Extreme ultraviolet solar spectra and spectroheliogram analyse

Continuous and discrete Clebsch variational principles

The Clebsch method provides a unifying approach for deriving variational principles for continuous and discrete dynamical systems where elements of a vector space are used to control dynamics on the cotangent bundle of a Lie group \emph{via} a velocity map. This paper proves a reduction theorem which states that the canonical variables on the Lie group can be eliminated, if and only if the velocity map is a Lie algebra action, thereby producing the Euler-Poincar\'e (EP) equation for the vector space variables. In this case, the map from the canonical variables on the Lie group to the vector space is the standard momentum map defined using the diamond operator. We apply the Clebsch method in examples of the rotating rigid body and the incompressible Euler equations. Along the way, we explain how singular solutions of the EP equation for the diffeomorphism group (EPDiff) arise as momentum maps in the Clebsch approach. In the case of finite dimensional Lie groups, the Clebsch variational principle is discretised to produce a variational integrator for the dynamical system. We obtain a discrete map from which the variables on the cotangent bundle of a Lie group may be eliminated to produce a discrete EP equation for elements of the vector space. We give an integrator for the rotating rigid body as an example. We also briefly discuss how to discretise infinite-dimensional Clebsch systems, so as to produce conservative numerical methods for fluid dynamics

Quantum computing with nearest neighbor interactions and error rates over 1%

Large-scale quantum computation will only be achieved if experimentally implementable quantum error correction procedures are devised that can tolerate experimentally achievable error rates. We describe a quantum error correction procedure that requires only a 2-D square lattice of qubits that can interact with their nearest neighbors, yet can tolerate quantum gate error rates over 1%. The precise maximum tolerable error rate depends on the error model, and we calculate values in the range 1.1--1.4% for various physically reasonable models. Even the lowest value represents the highest threshold error rate calculated to date in a geometrically constrained setting, and a 50% improvement over the previous record.Comment: 4 pages, 8 figure

Towards practical classical processing for the surface code

The surface code is unarguably the leading quantum error correction code for 2-D nearest neighbor architectures, featuring a high threshold error rate of approximately 1%, low overhead implementations of the entire Clifford group, and flexible, arbitrarily long-range logical gates. These highly desirable features come at the cost of significant classical processing complexity. We show how to perform the processing associated with an nxn lattice of qubits, each being manipulated in a realistic, fault-tolerant manner, in O(n^2) average time per round of error correction. We also describe how to parallelize the algorithm to achieve O(1) average processing per round, using only constant computing resources per unit area and local communication. Both of these complexities are optimal.Comment: 5 pages, 6 figures, published version with some additional tex

Sequence Effects on DNA Entropic Elasticity

DNA stretching experiments are usually interpreted using the worm-like chain model; the persistence length A appearing in the model is then interpreted as the elastic stiffness of the double helix. In fact the persistence length obtained by this method is a combination of bend stiffness and intrinsic bend effects reflecting sequence information, just as at zero stretching force. This observation resolves the discrepancy between the value of A measured in these experiments and the larger ``dynamic persistence length'' measured by other means. On the other hand, the twist persistence length deduced from torsionally-constrained stretching experiments suffers no such correction. Our calculation is very simple and analytic; it applies to DNA and other polymers with weak intrinsic disorder.Comment: LaTeX; postscript available at http://dept.physics.upenn.edu/~nelson/index.shtm

Does nitrous oxide harm the dentist?

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A universal velocity distribution of relaxed collisionless structures

Several general trends have been identified for equilibrated, self-gravitating collisionless systems, such as density or anisotropy profiles. These are integrated quantities which naturally depend on the underlying velocity distribution function (VDF) of the system. We study this VDF through a set of numerical simulations, which allow us to extract both the radial and the tangential VDF. We find that the shape of the VDF is universal, in the sense that it depends only on two things namely the dispersion (radial or tangential) and the local slope of the density. Both the radial and the tangential VDF's are universal for a collection of simulations, including controlled collisions with very different initial conditions, radial infall simulation, and structures formed in cosmological simulations.Comment: 13 pages, 6 figures; oversimplified analysis corrected; changed abstract and conclusions; significantly extended discussio

Shielding Effectiveness and Sheet Conductance of Nonwoven Carbon-Fiber Sheets

Nonwoven carbon-fiber sheets are often used to form a conductive layer in composite materials for electromagnetic shielding and other purposes. While a large amount of research has considered the properties of similar idealized materials near the percolation threshold, little has been done to provide validated analytic models suitable for materials of practical use for electromagnetic shielding. Since numerical models consume considerable computer resource and do not provide the insight which enables improved material design, an analytic model is of great utility for materials development. This paper introduces a new theoretical model for the sheet conductance of nonwoven carbon-fiber sheets built on the theory of percolation for 2-D conducting stick networks. The model accounts for the effects of sample thickness, fiber angle distribution, and contact conductance on the sheet conductance. The theory shows good agreement with Monte Carlo simulations and measurements of real materials in the supercritical percolation regime where the dimensionless areal concentration of fibers exceeds about 50. The theoretical model allows the rapid prediction of material shielding performance from a limited number of manufacturing parameters