Do waiting times reduce hospital costs?

Using a sample of 137 hospitals over the period 1998-2002 in the English National Health Service, we estimate the elasticity of hospital costs with respect to waiting times. Our cross-sectional and panel-data results suggest that at the sample mean (103 days), waiting times have no significant effect on hospital, costs or, at most, a positive one. If significant, the elasticity of cost with respect to waiting time from our cross-sectional estimates is in the range 0.4-1. The elasticity is still positive but lower in our fixed-effects specifications (0.2-0.4). In all specifications, the effect of waiting time on cost is non-linear, suggesting a U-shaped relationship between hospital costs and waiting times: the level of waiting time which minimises total costs is always below ten days.

Increased security through open source

In this paper we discuss the impact of open source on both the security and transparency of a software system. We focus on the more technical aspects of this issue, combining and extending arguments developed over the years. We stress that our discussion of the problem only applies to software for general purpose computing systems. For embedded systems, where the software usually cannot easily be patched or upgraded, different considerations may apply

ATM-CMG control system stability

Stability analyses and simulation data and results are presented for an initial Control Moment Gyroscope system proposed for the Apollo Telescope Mount cluster (later named Skylab) using momentum vector feedback. A compensation filtering technique is presented which significantly improved analytical and simulation performance of the system. This technique is quite similar to the complementary filtering technique and represents an early NASA application

Reviewing an integrated MBA core course: Working paper series--03-16

Entering the new century, business education must respond to changes in the work environment. The traditional job as we have known it is rapidly becoming rarer, and students find themselves in an environment of higher complexity, more competition, and faster change. Employers state that students are often unprepared to meet challenges of the new work environment. In response to these influences, a team of educators at Northern Arizona University's College of Business Administration redesigned their MBA program. Based on surveys of employers, alumni and others, core courses of the MBA program became functionally integrated, cross-disciplinary, more outcome-oriented, and more rigorous. The program core was integrated in its entirety; then, components of the core were "chunked" to fit traditional time slots for administrative reasons. This paper describes design and implementation efforts for one MBA core component: Individuals, Teams, and Careers. This component presents students with an integrated view of their own strengths and weaknesses as they relate to personal, team, and career issues for students' pursuit of careers after graduation. Course content is strongly based on self-evaluations by students, then moves into group interaction strategies and skills, and finally focuses on reciprocal interactions of the person and the work environment. The multiple foci of this component include students' careers as future managers, management of their own careers and career mentorship of subordinates. Content development for the MBA program core, and thus for this component was a team effort, negotiated among the MBA redesign team. Six team members represented traditional functional areas of economics, finance, accounting, marketing, management, and computer information systems. Development and implementation of Individuals, Teams, and Careers fell to the authors as members of the MBA core faculty representing the management area. Course topics were team-taught by two management faculty members, as well as by economics, marketing, business law, and human resources faculty. In addition, guest presenters included specialists in leadership, arbitration, and a retired career manager who had been President of IBM's General Products Division. In its first iteration, the Individuals, Teams, and Careers component was presented during semester break between the first and second semesters of the MBA program. With this medial position in the core, much of the team content was based on students' retrospective views of team interaction and performance during the first half of the program. The course has since been moved to the beginning of the course sequence. In this current position, this "chunk" appears as one of two initial program components and fulfills the socialization and expectations-setting function for individual and team performance in the program, as well as addressing career management at the start of the program. This paper describes the integrated content of this MBA program component, including its multiple focus and its outcome orientation. In addition, dimensions of the team-teaching experience in this course component are examined. Finally, students' responses to this component are reported, relative to content and pedagogy. We expect other educators will benefit from seeing Northern Arizona University's response to the dramatically changing environment of the 21st century

Sparse Bayesian Nonlinear System Identification using Variational Inference

IEEE Bayesian nonlinear system identification for one of the major classes of dynamic model, the nonlinear autoregressive with exogenous input (NARX) model, has not been widely studied to date. Markov chain Monte Carlo (MCMC) methods have been developed, which tend to be accurate but can also be slow to converge. In this contribution, we present a novel, computationally efficient solution to sparse Bayesian identification of the NARX model using variational inference, which is orders of magnitude faster than MCMC methods. A sparsity-inducing hyper-prior is used to solve the structure detection problem. Key results include: 1. successful demonstration of the method on low signal-to-noise ratio signals (down to 2dB); 2. successful benchmarking in terms of speed and accuracy against a number of other algorithms: Bayesian LASSO, reversible jump MCMC, forward regression orthogonalisation, LASSO and simulation error minimisation with pruning; 3. accurate identification of a real world system, an electroactive polymer; and 4. demonstration for the first time of numerically propagating the estimated nonlinear time-domain model parameter uncertainty into the frequency-domain

Contemporary medical television and crisis in the NHS

This article maps the terrain of contemporary UK medical television, paying particular attention to Call the Midwife as its centrepiece, and situating it in contextual relation to the current crisis in the NHS. It provides a historical overview of UK and US medical television, illustrating how medical television today has been shaped by noteworthy antecedents. It argues that crisis rhetoric surrounding healthcare leading up to the passing of the Health and Social Care Act 2012 has been accompanied by a renaissance in medical television. And that issues, strands and clusters have emerged in forms, registers and modes with noticeable regularity, especially around the value of affective labour, the cultural politics of nostalgia and the neoliberalisation of healthcare

On the existence and structure of a mush at the inner core boundary of the Earth

It has been suggested about 20 years ago that the liquid close to the inner core boundary (ICB) is supercooled and that a sizable mushy layer has developed during the growth of the inner core. The morphological instability of the liquid-solid interface which usually results in the formation of a mushy zone has been intensively studied in metallurgy, but the freezing of the inner core occurs in very unusual conditions: the growth rate is very small, and the pressure gradient has a key role, the newly formed solid being hotter than the adjacent liquid. We investigate the linear stability of a solidification front under such conditions, pointing out the destabilizing role of the thermal and solutal fields, and the stabilizing role of the pressure gradient. The main consequence of the very small solidification rate is the importance of advective transport of solute in liquid, which tends to remove light solute from the vicinity of the ICB and to suppress supercooling, thus acting against the destabilization of the solidification front. For plausible phase diagrams of the core mixture, we nevertheless found that the ICB is likely to be morphologically unstable, and that a mushy zone might have developed at the ICB. The thermodynamic thickness of the resulting mushy zone can be significant, from $\sim100$ km to the entire inner core radius, depending on the phase diagram of the core mixture. However, such a thick mushy zone is predicted to collapse under its own weight, on a much smaller length scale ($\lesssim 1$ km). We estimate that the interdendritic spacing is probably smaller than a few tens of meter, and possibly only a few meters

Kinetic energy driven superconductivity in doped cuprates

Within the t-J model, the mechanism of superconductivity in doped cuprates is studied based on the partial charge-spin separation fermion-spin theory. It is shown that dressed holons interact occurring directly through the kinetic energy by exchanging dressed spinon excitations, leading to a net attractive force between dressed holons, then the electron Cooper pairs originating from the dressed holon pairing state are due to the charge-spin recombination, and their condensation reveals the superconducting ground-state. The electron superconducting transition temperature is determined by the dressed holon pair transition temperature, and is proportional to the concentration of doped holes in the underdoped regime. With the common form of the electron Cooper pair, we also show that there is a coexistence of the electron Cooper pair and antiferromagnetic short-range correlation, and hence the antiferromagnetic short-range fluctuation can persist into the superconducting state. Our results are qualitatively consistent with experiments.Comment: 6 pages, Revtex, two figures are included, corrected typo

Electron spectral function and algebraic spin liquid for the normal state of underdoped high TcT_c superconductors

We propose to describe the spin fluctuations in the normal state of underdoped high $T_{c}$ superconductors as a manifestation of an algebraic spin liquid. We have performed calculations within the slave-boson model to support our proposal. Under the spin-charge separation picture, the normal state (the spin-pseudogap phase) is described by massless Dirac fermions, charged bosons, and a gauge field. We find that the gauge interaction is a marginal perturbation and drives the mean-field free-spinon fixed point to a more complicated spin-quantum-fixed-point -- the algebraic spin liquid, where gapless excitations interact at low energies. The electron spectral function in the normal state was found to have a Luttinger-liquid-like line shape as observed in experiments. The spectral function obtained in the superconducting state shows how a coherent quasiparticle peak appears from the incoherent background as spin and charge recombine.Comment: 4 pages, 3 figures. published versio