A stochastic model for MRSA transmission within a hospital ward incorporating environmental contamination.

Methicillin-resistant Staphylococcus aureus (MRSA) transmission in hospital wards is associated with adverse outcomes for patients and increased costs for hospitals. The transmission process is inherently stochastic and the randomness emphasized by the small population sizes involved. As such, a stochastic model was proposed to describe the MRSA transmission process, taking into account the related contribution and modelling of the associated microbiological environmental contamination.

Recent warming by latitude associated with increased length of ragweed pollen season in central North America.

A fundamental aspect of climate change is the potential shifts in flowering phenology and pollen initiation associated with milder winters and warmer seasonal air temperature. Earlier floral anthesis has been suggested, in turn, to have a role in human disease by increasing time of exposure to pollen that causes allergic rhinitis and related asthma. However, earlier floral initiation does not necessarily alter the temporal duration of the pollen season, and, to date, no consistent continental trend in pollen season length has been demonstrated.

Elastohydrodynamics of the eyelid wiper.

This paper presents an elastohydrodynamic model of the human eyelid wiper. Standard lubrication theory is applied to the fluid layer between the eyelid wiper and ocular surface. The role of the lubrication film is to reduce the shear stresses by preventing solid to solid contact between the eyelid wiper and ocular surface.

The effect of the lipid layer on tear film behaviour.

This paper investigates the effect of surfactants during tear film deposition and subsequent thinning. The surfactants occur naturally on the surface of the tear film in the form of a lipid layer. A lubrication model is developed that describes lipid spreading and film height evolution.

Dynamics of tear film deposition and draining.

This paper investigates the deposition of the tear film on the cornea of the human eye. The tear film is laid down by the motion of the upper eyelid and then subsequently flows and thins. Of particular interest is the stability of the tear layer and the development of dry patches on the cornea.

The metapopulation dynamics of an infectious disease: tuberculosis in possums.

An SEI metapopulation model is developed for the spread of an infectious agent by migration. The model portrays two age classes on a number of patches connected by migration routes which are used as host animals mature. A feature of this model is that the basic reproduction ratio may be computed directly, using a scheme that separates topography, demography, and epidemiology.

Periodic triggering of an inducible gene for control of a wild population.

A possible method of control for the management of wild populations consists of continual introgression of an inducible transgene by releasing transgenic individuals, with periodic exposure of the population to a trigger. Exposure to the trigger causes death or sterility in carriers of the transgene, but is otherwise benign. We investigate the effectiveness of various strategies for control.

Swimming of spermatozoa in a linear viscoelastic fluid.

A modified resistive force theory is developed for a spermatozoon swimming in a general linear viscoelastic fluid. The theory is based on a Fourier decomposition of the flagellar velocity, which leads to solving the Stokes flow equations with a complex viscosity. We use a model spermatozoon with a spherical head which propagates small amplitude sinusoidal waves along its flagellum.

Modelling the integration of a transgene by stocking.

Simple models for the integration of a selectively neutral transgene into a feral population, by stocking of transgenic individuals, are developed. The impact of stocking individuals having multiple unlinked homozygous locations of the transgene is quantified. Initially it is assumed that there is no overlap between successive generations but a more general model for species having discrete overlapping generations is also developed.

Hydrodynamics of filter feeding.

A fluid mechanical model is developed for the filtering mechanism in mussels that enables estimates to be made of the pressure drop through the gill filaments due to (i) the latero-frontal filtering cilia, (ii) the lateral (pumping) cilia and through the non-ciliated zone at the ventral end of the filament. Calculations indicate that the lateral cilia can generate a sufficient pressure change to 'pump' water through the gill filaments. The velocity profile across the filaments indicates that a backflow can occur in the centre of the channel.

A prospective study of nonoperative and operative management for Perthes' disease.

Two groups of children with Perthes' disease, randomized according to their source of referral, were treated by bed rest and skin traction, followed by either use of a weight-relieving caliper or a proximal femoral varus osteotomy. The outcome was similar in both groups and could be predicted more effectively by the arthrographic shape of the femoral head at presentation than by the Catterall grouping. The principal influences were the age of the child when treated and the sphericity of the femoral head.

Surgical management of ankle and foot deformities in cerebral palsy.

A system of surgical treatment of deformities of the ankle and foot in cerebral palsy is presented on the basis of experience with 420 children. The aim of surgery is prevention or correction of deformities. There are three types of deformity (fixed, dynamic, and mixed), each of which is treated differently.

Dynamic inversion of the forefoot and dorsiflexion of the big toe treated by transfer of extensor hallucis longus.

Dynamic hyperextension of the big toe and supination of the forefoot may occur in the swing phase of walking in children with various neurological disorders. Symptoms arising from this have been successfully corrected in 13 feet of 11 children by transfer of extensor hallucis longus to the insertion of peroneus brevis.

A study of normal baby movements.

Twenty-five normal newborns aged between 3 and 6 days had their movements recorded by clinical observation in a controlled environment, chart recording from an automatic movement mattress over 4 hours, and cine photography triggered by the movement mattress. Over 80 different individual types of movement were grouped into six categories: progression movements (obligatory reciprocal movements), symmetrical movements (slower flexion or extension movements), startle movements, asymmetrical tonic neck reflex and 'Moro', facial movements and athetoid movements. The normal newborn's motor activity is significantly related to the level of arousal, gestational age, and environmental variables such as position, temperature, light and noise.

Muco-ciliary transport in the lung.

A two-layer Newtonian fluid model for muco-ciliary transport in the lung is developed where the viscosity of the upper mucous layer is very much greater than the viscosity of the lower periciliary layer. Theory is presented for both cases when the cilia penetrate, and do not penetrate, the very viscous mucous layer. Calculations suggest that, in normal circumstances, it is not essential for the cilia to penetrate the mucus to provide positive transport.

Treatment of valgus hindfoot in cerebral palsy by peroneus brevis lengthening.

Twenty cerebral-palsied patients (30 feet) with hindfoot valgus due to muscle imbalance were reviewed and it was shown that the deformity can be reduced by peroneus brevis lengthening. The method of choice is intramuscular lengthening, which reduces the power of peroneus brevis by one point on the MRC grading and corrects the hindfoot valgus by one grade of severity. For full correction by tendon lengthening, the deformity must be treated while it is still mild.

Bilateral failure of the capital femoral epiphysis: bilateral Perthes disease, multiple epiphyseal dysplasia, pseudoachondroplasia, and spondyloepiphyseal dysplasia congenita and tarda.

A radiographic survey of 25 patients with bilateral Perthes disease is compared with four inherited skeletal dysplasias also affecting the hip joints (45 patients with multiple epiphyseal dysplasia, 22 with spondyloepiphyseal dysplasia tarda, 18 with pseudoachondroplasia, and 17 with spondyloepiphyseal dysplasia congenita). The distinguishing features in relation to the pelvis and hip joint in the growing child are ascertained, in view of the importance of differentiating as early as possible the transient disorder of Perthes disease from the more serious progressive disorders.

Clinical variation in dyschondrosteosis. A report on 13 individuals in 8 families.

Thirteen patients with dyschondrosteosis from eight families are reviewed and their clinical and radiographic variation noted. Inheritance is likely to be autosomal dominant but with only 50 per cent penetrance. Stature was moderately reduced, due to shortening of the bones of the leg.

A review of the morphology of Perthes' disease.

There are differences of opinion about the pathogenesis of Perthes' disease. All are agreed that it is due to ischaemia, but the cause of this and the size and number of infarctions are in dispute. Through the generosity of the contributors six whole femoral heads and core biopsies of five other cases have been studied radiographically and histologically.

Spina bifida and cerebral palsy.

A new test of posture and mobility has been applied to a small group of spina bifida children with different lower limb motor levels, and to a further group of children with both spina bifida and associated cerebral palsy of the hemiplegic type. It is demonstrated that this test of posture and mobility is applicable to spina bifida children and that gross motor handicap is therefore quantifiable. The posture and mobility scores of children with spina bifida or cerebral palsy is significantly less than those of normal children and the scores for children with both spina bifida as well as cerebral palsy is significantly lower than having either alone.