A Demand and Capacity Model For Home-Based Intermediate Care: Optimizing The ‘Step Down’ Pathway

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordIntermediate care supports timely discharge from hospital for patients with complex healthcare needs. The purpose of 'step-down' care is to enable patients to leave hospital as soon as medically fit, avoiding costly discharge delays and consequent risks to patient health and wellbeing. Determining optimal intermediate care capacity requires balancing costs to both acute hospital and community care providers. Too much community capacity results in underutilized resources and poor economic efficiency, while too little risks excessive hospital discharge delays. Application of discrete-time simulation shows that total costs across the acute-community interface can be minimized by identifying optimal community capacity in terms of the maximum number of patients for which home visits can be provided by the service. To our knowledge, this is the first simulation study to model the patient pathway from hospital discharge through to community visits. Simulation modeling has supported short-term resource planning in a major English healthcare system.Health Data Research U

Pairs Emission in a Uniform Background Field: an Algebraic Approach

A fully algebraic general approach is developed to treat the pairs emission and absorption in the presence of some uniform external background field. In particular, it is shown that the pairs production and annihilation operators, together with the pairs number operator, do actually fulfill the SU(2) functional Lie algebra. As an example of application, the celebrated Schwinger formula is consistently and nicely recovered, within this novel approach, for a Dirac spinor field in the presence of a constant and homogeneous electric field in four spacetime dimensions.Comment: 26 pages, no figure

Hamiltonian Light-Front Field Theory: Recent Progress and Tantalizing Prospects

Fundamental theories, such as Quantum Electrodynamics (QED) and Quantum Chromodynamics (QCD) promise great predictive power addressing phenomena over vast scales from the microscopic to cosmic scales. However, new non-perturbative tools are required for physics to span from one scale to the next. I outline recent theoretical and computational progress to build these bridges and provide illustrative results for Hamiltonian Light Front Field Theory. One key area is our development of basis function approaches that cast the theory as a Hamiltonian matrix problem while preserving a maximal set of symmetries. Regulating the theory with an external field that can be removed to obtain the continuum limit offers additional possibilities as seen in an application to the anomalous magnetic moment of the electron. Recent progress capitalizes on algorithm and computer developments for setting up and solving very large sparse matrix eigenvalue problems. Matrices with dimensions of 20 billion basis states are now solved on leadership-class computers for their low-lying eigenstates and eigenfunctions.Comment: 8 pages with 2 figure

Interference Effects in Schwinger Vacuum Pair Production for Time-Dependent Laser Pulses

We present simple new approximate formulas, for both scalar and spinor QED, for the number of particles produced from vacuum by a time dependent electric field, incorporating the interference effects that arise from an arbitrary number of distinct semiclassical turning points. Such interference effects are important when the temporal profile of the laser pulse has subcycle structure. We show how the resulting semiclassical intuition may be used to guide the design of temporal profiles that enhance the momentum spectrum due to interference effects. The result is easy to implement and generally applicable to time-dependent tunneling problems, such as appear in many other contexts in particle and nuclear physics, condensed matter physics, atomic physics, chemical physics, and gravitational physics.Comment: 19 pages; 21 figures; v2 refs update

Toward the observation of interference effects in nonlinear Compton scattering

The photon spectrum from electrons scattering on multiple laser pulses exhibits interference effects not present for scattering on a single pulse. We investigate the conditions required for the experimental observation of these interference effects in electron-laser collisions, in particular analysing the roles of the detector resolution and the transverse divergence of the pump electron beam.Comment: 8 pages, 5 figure