The development and use of tools for monitoring the occurrence of surgical wound infections

Infections acquired during patients' hospital stays are a major health care concern in the UK. They can be fatal, lead to excess morbidity and lengthen hospital stay. There is therefore considerable interest in using analytical tools for monitoring the occurrence of infections so that any problems with the quality of patient care can be quickly identified and rectified. The development and implementation of such tools are complicated as some infections can be difficult to diagnose and it can take several weeks before an infection manifests itself. Another important issue is that some patients are more likely to contract an infection than others, regardless of the standard of care they receive. This paper describes work that has been undertaken in collaboration with University College London Hospitals (UCLH) to develop appropriate outcome monitoring tools for surgical wound infections that are easy for hospital staff to use and interpret. The underlying risk model has been developed and validated locally at UCLH, and for more widespread implementation it would require revalidation for new centres.     

Examining the feasibility of using a modelling tool to assess resilience across a health-care system and assist with decisions concerning service reconfiguration

Changes in medical practice, demographic shifts and financial pressures are all examples of factors that may contribute to demand for periodic changes in the configuration of health services. When reconfiguring a service, health planners often take into account projected demand for services, patient access criteria and budgetary constraints (among other things), but typically give little consideration regarding its resilience to deliver services during and after external disruptions to its capability to deliver. In this paper we discuss a study conducted in response to a direct request from the National Health Service (NHS) Resilience Project within the Department of Health to explore the feasibility of assessing resilience across local services within the NHS and developing a computer software tool to assess resilience of different service reconfigurations. We give an account of the modelling process used, including the analytical framework we developed using both optimisation and heuristic methods, and an illustrative example of usage of a prototype software tool. We also highlight the key lessons that emerged during this project, which may be helpful to OR analysts working on similar projects regarding resilience in the public sector.     

Measurement of the differential cross section and the spin-correlation parameters P,A and R in the backward peak of π−p→K0Λ at 5 GeV/c

We present measurements for the baryon-exchange reaction π^?p→ΛK⁰ at 5 GeV/c over the range ?u<2(GeV/c)². The differential cross section is obtained from events produced on a liquid hydrogen target. These data are combined with events produced on a butanol polarized target and the parameters P, A, and R are then determined from an analysis of the decay angular distribution of the forward-going Λ. From our data it is possible to determine the magnitudes and the relative phase of the two invariant amplitudes A′ and B. The consequences for the ratio B/A′ are discussed in detail.     

AN EVALUATION OF THE BOUNCE-BACK BOUNDARY CONDITION FOR LATTICE BOLTZMANN SIMULATIONS

The bounce-back boundary condition for lattice Boltzmann simulations is evaluated for flow about an infinite periodic array of cylinders. The solution is compared with results from a more accurate boundary condition formulation for the lattice Boltemann method and with finite difference solutions. The bounce-back boundary condition is used to simulate boundaries of cylinders with both circular and octagonal cross-sections. The convergences of the velocity and total drag associated with this method are slightly sublinear with grid spacing. Error is also a function of relaxation time, increasing exponentially for large relaxation times. However, the accuracy does not exhibit a trend with Reynolds number between 0·1 and 100. The square lattice Boltzmann grid conforms to the octagonal cylinder but only approximates the circular cylinder, and the resulting error associated with the octagonal cylinder is half the error of the circular cylinder. The bounce-back boundary condition is shown to yield accurate lattice Boltzmann simulations with reduced computational requirements for computational grids of 170×170 or finer, a relaxation time less than 1·5 and any Reynolds number from 0·1 to 100. For this range of parameters the root mean square error in velocity and the relative error in drag coefficient are less than 1 per cent for the octagonal cylinder and 2 per cent for the circular cylinder. © 1997 John Wiley & Sons, Ltd.     

Bilateral Vocal Fold Posterior Glottic/Subglottic Stenotic Web Resected with Contact Tip Nd-YAG Laser

The standard treatment for respiratory failure remains endotracheal intubation, with periods of 22 or more days being commonplace. Posterior glottic stenotic web formation, from scarring in the posterior interarytenoid area, may occur after endotracheal intubation, thermal, corrosive, or direct surgical injury. A commonly used classification system for posterior glottic stenosis divides the occurrence into four types. Type I involves an interarytenoid scar band between the vocal folds that is anterior and separate from the posterior interarytenoid mucosa. Type II stenosis involves scarring of the mucosa or musculature of the posterior interarytenoid area. Types III and IV involve unilateral and bilateral cricoarytenoid joint fixation, respectively. Strobovideolaryngoscopy (SVL), rigid and flexible fiberoptic bronchoscopy, electromyography (EMG), radiologic imaging of the neck, larynx, and trachea as well as pulmonary function tests, including flow volume loops, provide important objective measurements of upper airway obstruction. A representative case of a professional voice user who suffered a Type II posterior glottic stenosis is presented. The treatment utilized a specific contact-tip neodymium-yttrium aluminum garnet (Nd-YAG) laser delivery system to achieve precise cutting, vaporization, and coagulation simultaneously, returning tactile touch technique to the airway/voice surgeon. Completely successful restoration of voice and airway have been maintained for 2 1/2 years postoperatively.     

Bilateral Mixed Laryngoceles: Simultaneous Strobovideolaryngoscopy and External Video Examination

A music medicine practice affords a unique opportunity to diagnose and treat laryngeal music performers. Strobovideolaryngoscopic (SVL) and external video examination of the voice professional or brass instrument player may focus on the vocal folds, yet abnormalities of the supraglottis, neck, and thorax should be appreciated and documented. Laryngoceles are uncommon laryngeal disorders but may occur in up to 5% of benign laryngeal lesions. While many laryngoceles are asymptomatic, they may cause a cough, hoarseness, stridor, sore throat, pain, snoring, or globus sensation. In particular, musicians who play brass instruments are at high risk for laryngocele development. We highlight two patients with symptomatic laryngoceles to present anatomical, historical, classification, epidemiological, diagnostic, and management considerations.     

On the number of disjoint increasing paths in the one-skeleton of a convex body leading to a given exposed face

It is shown that ifF is ann-dimensional exposed face of ad-dimensional convex body and iff is a linear functional whose maximum value on the body is attained over the whole ofF thenn+1 paths can be found in the one-skeleton of the body leading toF and disjoint except at their end-points. Further, such paths may be found having the property that along them, the value off strictly increases. It is further shown that unlessn=0 it may be impossible to findn+2 such paths.     

Measurement of diffractive 3π production on a polarized target at 17 GeV/c

The reaction π^?p↑→π^?π⁺π^?p has been measured at 17 GeV/c using a polarized target. The data sample contains about 60 000 interactions on polarized protons. The nucleon polarization as a function of momentum transfer is very similar to elastic π^?p scattering and is nearly independent of the π mass, except for a possible structure around 1.2 GeV.Using the isobar model, we have performed a partial-wave analysis and extracted the 3π amplitudes. The generalized 3π density matrix elements agree with earlier determinations. Relative phases obtained from density matrix elements agree well with the ones obtained from transversity amplitudes. This proves the validity of the coherence assumption made in the interpretation of unpolarized target results. Our results confirm the existence of an A₁ resonance in the region 1.2–1.3 GeV.     

A neutral, water-soluble olefin metathesis catalyst based on an N-heterocyclic carbene ligand

A water-soluble ruthenium-based olefin metathesis catalyst supported by a poly(ethylene glycol) conjugated N-heterocyclic carbene ligand is reported. The catalyst displays greater activity in aqueous ring-opening metathesis polymerization (ROMP) reactions than previously reported water-soluble metathesis catalysts.