The risk of unintentional out-of-network encounters with hospital-based physicians at in-network hospitals.

Objective: When hospital-based specialists including emergency physicians, anesthesiologists, pathologists and radiologists are not included in the same insurance networks as their parent hospitals, it creates confusion and leads to unexpected costs for patients. This study explored the frequency with which hospital-based physicians at academic medical centers are not included in the network directories for the same insurance networks as their parent teaching hospitals.

Methods: We studied teaching hospitals with residency programs in all four hospital-based specialties.

Non-abelian Weyl commutation relations and the series product of quantum stochastic evolutions.

We show that the series product, which serves as an algebraic rule for connecting state-based input-output systems, is intimately related to the Heisenberg group and the canonical commutation relations. The series product for quantum stochastic models then corresponds to a non-abelian generalization of the Weyl commutation relation. We show that the series product gives the general rule for combining the generators of quantum stochastic evolutions using a Lie-Trotter product formula.

On structure-preserving transformations of the Ito generator matrix for model reduction of quantum feedback networks.

Two standard operations of model reduction for quantum feedback networks, elimination of internal connections under the instantaneous feedback limit and adiabatic elimination of fast degrees of freedom, are cast as structure-preserving transformations of Itō generator matrices. It is shown that the order in which they are applied is inconsequential.

Single photon quantum filtering using non-Markovian embeddings.

We determine quantum master and filter equations for continuous measurement of systems coupled to input fields in certain non-classical continuous-mode states, specifically single photon states. The quantum filters are shown to be derivable from an embedding into a larger non-Markovian system, and are given by a system of coupled stochastic differential equations.

Principles and applications of quantum control engineering.

This is a brief survey of quantum feedback control and specifically follows on from the two-day conference Principles and applications of quantum control engineering, which took place in the Kavli Royal Society International Centre at Chicheley Hall, on 12-13 December 2011. This was the eighth in a series of principles and applications of control to quantum systems workshops.

Can peak expiratory flow measurements differentiate chronic obstructive pulmonary disease from congestive heart failure?

Dyspneic patients are commonly encountered by Emergency Medical Service (EMS). Frequent causes include Chronic Obstructive Pulmonary Disease (COPD) and Congestive Heart Failure (CHF). Measurement of peak expiratory flow rate (PEFR) has been proposed to help differentiate COPD from CHF.