14,227 research outputs found
Downsizing of acute inpatient beds associated with private finance initiative: Scotland's case study
OBJECTIVES: To evaluate whether the projected 24% reduction in acute bed numbers in Lothian hospitals, which formed part of the private finance initiative (PFI) plans for the replacement Royal Infirmary of Edinburgh, is being compensated for by improvements in efficiency and greater use of community facilities, and to ascertain whether there is an independent PFI effect by comparing clinical activity and performance in acute specialties in Lothian hospitals with other NHS hospitals in Scotland. DESIGN: Comparison of projected and actual trends in acute bed capacity and inpatient and day case admissions in the first five years (1995-6 to 2000-1) of Lothian Health Board's integrated healthcare plan. Population study of trends in bed rate, hospital activity, length of stay, and throughput in Lothian hospitals compared with the rest of Scotland from 1990-1 to 2000-1. MAIN OUTCOME MEASURES: Staffed bed rates, admission rates, mean lengths of stay, occupancy, and throughput in four adult acute specialty groups in 1990-1, 1995-6, and 2000-1. RESULTS: By 2000-1, rates for inpatient admission in all acute, medical, surgical, and intensive therapy specialties in Lothian hospitals were respectively 20%, 6%, 28%, and 38% below those in the rest of Scotland. Day case rates in all acute and acute surgical specialties were 13% and 33% lower. The proportion of delayed discharges in staffed acute and post-acute NHS beds in Lothian hospitals exceeded the Scottish average (15% and 12% respectively; P<0.001). CONCLUSION: The planning targets and increase in clinical activity in acute specialties in Lothian hospitals associated with PFI had not been achieved by 2000-1. The effect on clinical activity has been a steeper decline in the number of acute beds and rates of admission in Lothian hospitals compared with the rest of Scotland between 1995-6 and 2000-1
Tomographically reconstructed master equations for any open quantum dynamics
Memory effects in open quantum dynamics are often incorporated in the
equation of motion through a superoperator known as the memory kernel, which
encodes how past states affect future dynamics. However, the usual prescription
for determining the memory kernel requires information about the underlying
system-environment dynamics. Here, by deriving the transfer tensor method from
first principles, we show how a memory kernel master equation, for any quantum
process, can be entirely expressed in terms of a family of completely positive
dynamical maps. These can be reconstructed through quantum process tomography
on the system alone, either experimentally or numerically, and the resulting
equation of motion is equivalent to a generalised Nakajima-Zwanzig equation.
For experimental settings, we give a full prescription for the reconstruction
procedure, rendering the memory kernel operational. When simulation of an open
system is the goal, we show how our procedure yields a considerable advantage
for numerically calculating dynamics, even when the system is arbitrarily
periodically (or transiently) driven or initially correlated with its
environment. Namely, we show that the long time dynamics can be efficiently
obtained from a set of reconstructed maps over a much shorter time.Comment: 10+4 pages, 5 figure
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Dismantling the signposts to public health? NHS data under the Health and Social Care Act 2012
The Health and Social Care Act 2012 will replace the administrative structure of the NHS in England, currently based on the resident populations of defined geographical areas, with one that relates instead to the shifting populations of individuals registered with specific general practices at given points in time.1 This will radically change the longstanding basis for collecting data routinely about the health needs of local populations, making it difficult to monitor the effect of new legislation on the health of the population locally or nationally.2 3 We discuss some of the implications of the act for existing routine data systems and the production of routine statistics that underpin essential NHS functions, including monitoring healthcare provision and ensuring equity of access, allocation of resources, and measurement of outcomes
An introduction to operational quantum dynamics
In the summer of 2016, physicists gathered in Torun, Poland for the 48th
annual Symposium on Mathematical Physics. This Symposium was special; it
celebrated the 40th anniversary of the discovery of the
Gorini-Kossakowski-Sudarshan-Lindblad master equation, which is widely used in
quantum physics and quantum chemistry. This article forms part of a Special
Volume of the journal Open Systems & Information Dynamics arising from that
conference; and it aims to celebrate a related discovery -- also by Sudarshan
-- that of Quantum Maps (which had their 55th anniversary in the same year).
Nowadays, much like the master equation, quantum maps are ubiquitous in physics
and chemistry. Their importance in quantum information and related fields
cannot be overstated. In this manuscript, we motivate quantum maps from a
tomographic perspective, and derive their well-known representations. We then
dive into the murky world beyond these maps, where recent research has yielded
their generalisation to non-Markovian quantum processes.Comment: Submitted to Special OSID volume "40 years of GKLS
Non-Markovian memory in IBMQX4
We measure and quantify non-Markovian effects in IBM's Quantum Experience.
Specifically, we analyze the temporal correlations in a sequence of gates by
characterizing the performance of a gate conditioned on the gate that preceded
it. With this method, we estimate (i) the size of fluctuations in the
performance of a gate, i.e., errors due to non-Markovianity; (ii) the length of
the memory; and (iii) the total size of the memory. Our results strongly
indicate the presence of non-trivial non-Markovian effects in almost all gates
in the universal set. However, based on our findings, we discuss the potential
for cleaner computation by adequately accounting the non-Markovian nature of
the machine.Comment: 8 page
Tight, robust, and feasible quantum speed limits for open dynamics
Starting from a geometric perspective, we derive a quantum speed limit for
arbitrary open quantum evolution, which could be Markovian or non-Markovian,
providing a fundamental bound on the time taken for the most general quantum
dynamics. Our methods rely on measuring angles and distances between (mixed)
states represented as generalized Bloch vectors. We study the properties of our
bound and present its form for closed and open evolution, with the latter in
both Lindblad form and in terms of a memory kernel. Our speed limit is provably
robust under composition and mixing, features that largely improve the
effectiveness of quantum speed limits for open evolution of mixed states. We
also demonstrate that our bound is easier to compute and measure than other
quantum speed limits for open evolution, and that it is tighter than the
previous bounds for almost all open processes. Finally, we discuss the
usefulness of quantum speed limits and their impact in current research.Comment: Main: 11 pages, 3 figures. Appendix: 2 pages, 1 figur
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