6,089 research outputs found
Best interests, dementia and the Mental Capacity Act (2005)
The Mental Capacity Act (2005) is an impressive piece of
legislation that deserves serious ethical attention, but
much of the commentary on the Act has focussed on its
legal and practical implications rather than the underlying
ethical concepts. This paper examines the approach that
the Act takes to best interests. The Act does not provide
an account of the underlying concept of best interests.
Instead it lists factors that must be considered in
determining best interests, and the Code of Practice to
the Act states that this list is incomplete. This paper
argues that this general approach is correct, contrary to
some accounts of best interests. The checklist includes
items that are unhelpful. Furthermore, neither the Act nor
its Code of Practice provides sufficient guidance to carers
faced with difficult decisions concerning best interests.
This paper suggests ways in which the checklist can be
developed and discusses cases that could be used in an
updated Code of Practice
Stabilising entanglement by quantum jump-based feedback
We show that direct feedback based on quantum jump detection can be used to
generate entangled steady states. We present a strategy that is insensitive to
detection inefficiencies and robust against errors in the control Hamiltonian.
This feedback procedure is also shown to overcome spontaneous emission effects
by stabilising states with high degree of entanglement.Comment: 5 pages, 4 figure
Spatial mapping of hepatitis C prevalence in recent injecting drug users in contact with services.
In developed countries the majority of hepatitis C virus (HCV) infections occur in injecting drug users (IDUs) with prevalence in IDUs often high, but with wide geographical differences within countries. Estimates of local prevalence are needed for planning services for IDUs, but it is not practical to conduct HCV seroprevalence surveys in all areas. In this study survey data from IDUs attending specialist services were collected in 52/149 sites in England between 2006 and 2008. Spatially correlated random-effects models were used to estimate HCV prevalence for all sites, using auxiliary data to aid prediction. Estimates ranged from 14% to 82%, with larger cities, London and the North West having the highest HCV prevalence. The methods used generated robust estimates for each area, with a well-identified spatial pattern that improved predictions. Such models may be of use in other areas of study where surveillance data are sparse
Continuous measurement feedback control of a Bose-Einstein condensate using phase contrast imaging
We consider the theory of feedback control of a Bose-Einstein condensate
(BEC) confined in a harmonic trap under a continuous measurement constructed
via non-destructive imaging. A filtering theory approach is used to derive a
stochastic master equation (SME) for the system from a general Hamiltonian
based upon system-bath coupling. Numerical solutions for this SME in the limit
of a single atom show that the final steady state energy is dependent upon the
measurement strength, the ratio of photon kinetic energy to atomic kinetic
energy, and the feedback strength. Simulations indicate that for a weak
measurement strength, feedback can be used to overcome heating introduced by
the scattering of light, thereby allowing the atom to be driven towards the
ground state.Comment: 4 figures, 11 page
Synthetic monthly flow duration curves for the Cape Floristic Region, South Africa
A flow duration curve (FDC) provides a valuable planning and management tool since it describes the entire flow regime of a river. Water resource planning in South Africa is often based on monthly river flow data and synthetic FDCs are required for applications in ungauged catchments. The objective of this study was to derive 11 monthly FDC percentile flows andthe mean annual flow (MAQ) for catchments in the Cape Floristic Region of South Africa using regression equations with readily measureable catchment variables, including vegetation indices from Moderate Resolution Imaging Spectrometer (MODIS) satellite imagery. An ‘all-models’ approach with 10-fold validation was adopted to identify the ‘best’ regression models. Predictions of percentile flows above the median flow and MAQ were generally good but poor for low flows. Overall predictive uncertainty had a tendency to be larger in drier catchments. The most important predictive variables were catchment mean annual precipitation, physiography and soils. MODIS vegetation indices were significant predictors in equations for 6 percentile flows and MAQ, and predictive uncertainty increased if the MODIS indices were excluded from model development. The regression approach implemented in this study may be appropriate for other regionalisation studies that are based on a small sample of gauged catchments
Controlling entanglement by direct quantum feedback
We discuss the generation of entanglement between electronic states of two
atoms in a cavity using direct quantum feedback schemes. We compare the effects
of different control Hamiltonians and detection processes in the performance of
entanglement production and show that the quantum-jump-based feedback proposed
by us in Phys. Rev. A {\bf 76} 010301(R) (2007) can protect highly entangled
states against decoherence. We provide analytical results that explain the
robustness of jump feedback, and also analyse the perspectives of experimental
implementation by scrutinising the effects of imperfections and approximations
in our model.Comment: 10 pages, 8 figures. To appear in PR
Number-Phase Wigner Representation for Efficient Stochastic Simulations
Phase-space representations based on coherent states (P, Q, Wigner) have been
successful in the creation of stochastic differential equations (SDEs) for the
efficient stochastic simulation of high dimensional quantum systems. However
many problems using these techniques remain intractable over long integrations
times. We present a number-phase Wigner representation that can be unraveled
into SDEs. We demonstrate convergence to the correct solution for an anharmonic
oscillator with small dampening for significantly longer than other phase space
representations. This process requires an effective sampling of a non-classical
probability distribution. We describe and demonstrate a method of achieving
this sampling using stochastic weights.Comment: 7 pages, 1 figur
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