18,226 research outputs found
General practitioner empathy, patient enablement, and patient-reported outcomes in primary care in an area of high socio-economic deprivation in Scotland - a pilot prospective study using structural equation modelling
<b>Objective</b> The aim of this pilot prospective study was to investigate the relationships between general practitioners (GPs) empathy, patient enablement, and patient-assessed outcomes in primary care consultations in an area of high socio-economic deprivation in Scotland.<p></p>
<b>Methods</b> This prospective study was carried out in a five-doctor practice in an area of high socio-economic deprivation in Scotland. Patientsâ views on the consultation were gathered using the Consultation and Relational Empathy (CARE) Measure and the Patient Enablement Instrument (PEI). Changes in main complaint and well-being 1 month after the contact consultation were gathered from patients by postal questionnaire. The effect of GP empathy on patient enablement and prospective change in outcome was investigated using structural equation modelling.<p></p>
<b>Results</b> 323 patients completed the initial questionnaire at the contact consultation and of these 136 (42%) completed and returned the follow-up questionnaire at 1 month. Confirmatory factor analysis confirmed the construct validity of the CARE Measure, though omission of two of the six PEI items was required in order to reach an acceptable global data fit. The structural equation model revealed a direct positive relationship between GP empathy and patient enablement at contact consultation and a prospective relationship between patient enablement and changes in main complaint and well-being at 1 month.<p></p>
<b>Conclusion</b> In a high deprivation setting, GP empathy is associated with patient enablement at consultation, and enablement predicts patient-rated changes 1 month later. Further larger studies are desirable to confirm or refute these findings.<p></p>
<b>Practice implications</b> Ways of increasing GP empathy and patient enablement need to be established in order to maximise patient outcomes. Consultation length and relational continuity of care are known factors; the benefit of training and support for GPs needs to be further investigate
Universal Uncertainty Principle in the Measurement Operator Formalism
Heisenberg's uncertainty principle has been understood to set a limitation on
measurements; however, the long-standing mathematical formulation established
by Heisenberg, Kennard, and Robertson does not allow such an interpretation.
Recently, a new relation was found to give a universally valid relation between
noise and disturbance in general quantum measurements, and it has become clear
that the new relation plays a role of the first principle to derive various
quantum limits on measurement and information processing in a unified
treatment. This paper examines the above development on the noise-disturbance
uncertainty principle in the model-independent approach based on the
measurement operator formalism, which is widely accepted to describe a class of
generalized measurements in the field of quantum information. We obtain
explicit formulas for the noise and disturbance of measurements given by the
measurement operators, and show that projective measurements do not satisfy the
Heisenberg-type noise-disturbance relation that is typical in the gamma-ray
microscope thought experiments. We also show that the disturbance on a Pauli
operator of a projective measurement of another Pauli operator constantly
equals the square root of 2, and examine how this measurement violates the
Heisenberg-type relation but satisfies the new noise-disturbance relation.Comment: 11 pages. Based on the author's invited talk at the 9th International
Conference on Squeezed States and Uncertainty Relations (ICSSUR'2005),
Besancon, France, May 2-6, 200
Continuous measurements in a composite quantum system and possible exchange of information between its parts
We study an influence of the continuous measurement in a composite quantum
system C on the evolution of the states of its parts. It is shown that the
character of the evolution (decoherence or recoherence) depends on the type of
the measured quantity and on the initial state of the system. A number of
conditions under which the states of the subsystems of C decohere during the
measuring process are established. We propose a model of the composite system
and specify the observable the measurement of which may result in the
recoherence of the state of one of the subsystems of C. In the framework of
this model we find the optimal regime for the exchange of information between
the parts of C during the measurement. The main characteristics of such a
process are computed. We propose a scheme of detection of the recoherence under
the measurement in a concrete physical experiment.Comment: 6 page
Quantum control by von Neumann measurements
A general scheme is presented for controlling quantum systems using evolution
driven by non-selective von Neumann measurements, with or without an additional
tailored electromagnetic field. As an example, a 2-level quantum system
controlled by non-selective quantum measurements is considered. The control
goal is to find optimal system observables such that consecutive non-selective
measurement of these observables transforms the system from a given initial
state into a state which maximizes the expected value of a target operator (the
objective). A complete analytical solution is found including explicit
expressions for the optimal measured observables and for the maximal objective
value given any target operator, any initial system density matrix, and any
number of measurements. As an illustration, upper bounds on measurement-induced
population transfer between the ground and the excited states for any number of
measurements are found. The anti-Zeno effect is recovered in the limit of an
infinite number of measurements. In this limit the system becomes completely
controllable. The results establish the degree of control attainable by a
finite number of measurements
The quantumness of correlations revealed in local measurements exceeds entanglement
We analyze a family of measures of general quantum correlations for composite
systems, defined in terms of the bipartite entanglement necessarily created
between systems and apparatuses during local measurements. For every
entanglement monotone , this operational correspondence provides a different
measure of quantum correlations. Examples of such measures are the
relative entropy of quantumness, the quantum deficit, and the negativity of
quantumness. In general, we prove that any so defined quantum correlation
measure is always greater than (or equal to) the corresponding entanglement
between the subsystems, , for arbitrary states of composite quantum
systems. We analyze qualitatively and quantitatively the flow of correlations
in iterated measurements, showing that general quantum correlations and
entanglement can never decrease along von Neumann chains, and that genuine
multipartite entanglement in the initial state of the observed system always
gives rise to genuine multipartite entanglement among all subsystems and all
measurement apparatuses at any level in the chain. Our results provide a
comprehensive framework to understand and quantify general quantum correlations
in multipartite states.Comment: 6 pages, 2 figures; terminology slightly revised, few remarks adde
Information Transfer Implies State Collapse
We attempt to clarify certain puzzles concerning state collapse and
decoherence. In open quantum systems decoherence is shown to be a necessary
consequence of the transfer of information to the outside; we prove an upper
bound for the amount of coherence which can survive such a transfer. We claim
that in large closed systems decoherence has never been observed, but we will
show that it is usually harmless to assume its occurrence. An independent
postulate of state collapse over and above Schroedinger's equation and the
probability interpretation of quantum states, is shown to be redundant.Comment: 13 page
Weak measurement takes a simple form for cumulants
A weak measurement on a system is made by coupling a pointer weakly to the
system and then measuring the position of the pointer. If the initial
wavefunction for the pointer is real, the mean displacement of the pointer is
proportional to the so-called weak value of the observable being measured. This
gives an intuitively direct way of understanding weak measurement. However, if
the initial pointer wavefunction takes complex values, the relationship between
pointer displacement and weak value is not quite so simple, as pointed out
recently by R. Jozsa. This is even more striking in the case of sequential weak
measurements. These are carried out by coupling several pointers at different
stages of evolution of the system, and the relationship between the products of
the measured pointer positions and the sequential weak values can become
extremely complicated for an arbitrary initial pointer wavefunction.
Surprisingly, all this complication vanishes when one calculates the cumulants
of pointer positions. These are directly proportional to the cumulants of
sequential weak values. This suggests that cumulants have a fundamental
physical significance for weak measurement
Vibrations of micro-eV energies in nanocrystalline microstructures
The phonon density of states of nanocrystalline bcc Fe and nanocrystalline fcc Ni3Fe were measured by inelastic neutron scattering in two different ranges of energy. As has been reported previously, the nanocrystalline materials showed enhancements in their phonon density of states at energies from 2 to 15 meV, compared to control samples composed of large crystals. The present measurements were extended to energies in the micro-eV range, and showed significant, but smaller, enhancements in the number of modes in the energy range from 5 to 18 mueV. These modes of micro-eV energies provide a long-wavelength limit that bounds the fraction of modes at milli-eV energies originating with the cooperative dynamics of the nanocrystalline microstructure
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