A Transactional Analysis of Interaction Free Measurements

The transactional interpretation of quantum mechanics is applied to the "interaction-free" measurement scenario of Elitzur and Vaidman and to the Quantum Zeno Effect version of the measurement scenario by Kwiat, et al. It is shown that the non-classical information provided by the measurement scheme is supplied by the probing of the intervening object by incomplete offer and confirmation waves that do not form complete transactions or lead to real interactions.Comment: Accepted for publication in Foundations of Physics Letter

Exact relaxation in a class of non-equilibrium quantum lattice systems

A reasonable physical intuition in the study of interacting quantum systems says that, independent of the initial state, the system will tend to equilibrate. In this work we study a setting where relaxation to a steady state is exact, namely for the Bose-Hubbard model where the system is quenched from a Mott quantum phase to the strong superfluid regime. We find that the evolving state locally relaxes to a steady state with maximum entropy constrained by second moments, maximizing the entanglement, to a state which is different from the thermal state of the new Hamiltonian. Remarkably, in the infinite system limit this relaxation is true for all large times, and no time average is necessary. For large but finite system size we give a time interval for which the system locally "looks relaxed" up to a prescribed error. Our argument includes a central limit theorem for harmonic systems and exploits the finite speed of sound. Additionally, we show that for all periodic initial configurations, reminiscent of charge density waves, the system relaxes locally. We sketch experimentally accessible signatures in optical lattices as well as implications for the foundations of quantum statistical mechanics.Comment: 8 pages, 3 figures, replaced with final versio

Use of imaging in restorative stroke trials.

Restorative therapies aim to improve behavioral outcome after stroke by promoting repair and restoration. Measures of CNS injury and function might be useful to evaluate such therapies in a clinical trial, for example, by optimizing patient selection or treatment dose. These issues are considered in this review, with specific examples provided

An overview of therapies to promote repair of the brain after stroke.

Stroke remains a leading cause of disability. Most patients show some degree of spontaneous recovery, but this is generally incomplete. Studies on the neurobiology of this recovery are providing clues to therapeutic interventions that aim to improve patient outcomes. A number of potential such restorative therapies are reviewed. Numerous treatment strategies are under study. Most have a time window measured in days or weeks and so have the potential to help a large fraction of patients. This review considers these therapies, as well as points to consider in translating their application to human trials

Treatments to Promote Neural Repair after Stroke.

Stroke remains a major cause of human disability worldwide. In parallel with advances in acute stroke interventions, new therapies are under development that target restorative processes. Such therapies have a treatment time window measured in days, weeks, or longer and so have the advantage that they may be accessible by a majority of patients. Several categories of restorative therapy have been studied and are reviewed herein, including drugs, growth factors, monoclonal antibodies, activity-related therapies including telerehabilitation, and a host of devices such as those related to brain stimulation or robotics. Many patients with stroke do not receive acute stroke therapies or receive them and do not derive benefit, often surviving for years thereafter. Therapies based on neural repair hold the promise of providing additional treatment options to a majority of patients with stroke

Listening to fluoxetine: a hot message from the FLAME trial of poststroke motor recovery.

The fluoxetine for motor recovery after acute ischemic stroke study was a double blind, placebo-controlled trial examining the effects of fluoxetine in patients five- to 10 days after an ischemic stroke. The study found motor improvement to 90 days poststroke, measured as the change in the Fugl-Meyer score, was significantly greater in the fluoxetine group as compared with the placebo group, and that this finding was significant after adjusting for depression. Patients randomized to fluoxetine also had less disability (modified Rankin Scale 0-2). The study adds to the weight of data suggesting that viable strategies exist to improve patient outcomes by initiating a restorative agent, days after stroke injury is fixed. Stroke remains among the leading causes of human disability. Currently, a minority of patients can access approved reperfusion therapies, and among those so treated a substantial fraction derives limited benefit. Therapies that target restorative events have a time window measured in days-weeks and so hold the potential to help many patients with stroke