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. Patients’ 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 $E$, this operational correspondence provides a different measure $Q_E$ 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, $Q_E \ge E$, 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