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Abnormal clot microstructure plays a pivotal role in the pathophysiology of thromboembolic diseases. Assessing the viscoelastic properties of clot microstructure using novel parameters, Time to Gel Point (T GP ), Fractal Dimension (d f ) and clot elasticity (G׳ GP ) could explain the increased cardiovascular and thromboembolic events in patients with Obstructive Sleep Apnoea Hypopnea Syndrome (OSAHS). We wanted to compare T GP , d f , and G׳ GP and their diurnal variation in OSAHS and symptomatic comparators. thirty six patients attending a sleep disturbed breathing clinic with symptoms of OSAHS were recruited. T GP , d f and G׳ GP were measured alongside standard coagulation screening, thrombin generation assays, and platelet aggregometry at 16:00 h and immediately after an in-patient sleep study at 07:30 h. OSAHS group had significantly lower afternoon d f than comparators (1.705±0.033 vs. 1.731±0.031, p

HIV affects 33.2 million people worldwide, including 2.5 million children. An estimated 77,000 people are affected in the UK, a quarter of whom are unaware of their diagnosis; each year there are more than 7000 new cases. HIV results in slowly progressive immunodeficiency and/or progressive neurodegeneration. Disease markers are CD4 count and viral load. With a CD4 count below 500 cells/ml, generalized symptoms of decreased immunological function occur including fatigue and minor cognitive decline. With a count below 200 cells/ml, opportunistic infections, neoplasms, and HIV-related dementia develop. When the count falls below 50 cells/ml, fatal HIV-related illnesses develop. HIV is treated with three main classes of antiretroviral; often three or more drugs are required. Antiretroviral treatment may cause psychological symptoms, particularly mood and sleep problems. In resource-rich countries with access to antiretrovirals, HIV has become a chronic disease, altering the profile of associated mental health problems. Organic problems such as encephalitis, meningitis and other deliriums, and dementia have declined, as have adjustment disorders and manic presentations. Depression and anxiety have increased and problems specific to survival, adherence, and risk-reduction behaviours have emerged. Psychosexual problems are also important. Certain groups are particularly vulnerable to contracting HIV; amongst them are people with pre-existing psychiatric problems and drug use. A wide range of psychological and pharmacological treatments is available, some of which are HIV specific. Caution should be exercised in prescribing psychotropic medication because of the potential difficulties that can arise from interactions with antiretrovirals, not least the reduction in efficacy of antiretroviral medication.

We report the results of experiments designed to test the hypothesis that the enhanced levels of extensional viscosity conferred upon a liquid due to a polymer additive substantially mitigate cavitation damage, in addition to substantially increasing the liquid's cavitation threshold stress. As far as we are aware, these issues have never been directly addressed in a single investigation, involving samples of the same polymer system, in complementary experiments expressly designed for these purposes. The cavitation thresholds of aqueous PAA solutions are measured under dynamic stressing by pulses of tension and cavitation erosion experiments involving solid target specimens are also reported. The cavitation threshold of the solutions is found to be substantially enhanced by the presence of the polymer and the damage patterns recorded by scanning electron microscopy after 80 min exposure to cavitation in polymer solutions differ significantly from those in water. Whereas in water the surface presents heavily eroded areas with deep pitting cavities, in the 1% PAA solution the damage appears only in the form of individual craters that accumulate along specific lines and large undamaged areas (a stringy damage pattern). The weight loss decreases with increasing the polymer concentration and is one order of magnitude smaller in the 1% PAA solution than in the case of water. The present results suggest that the reduction of the maximum pressure inside the bubble at its minimum volume upon addition of polymer is the dominant mechanism of the observed suppression of cavitation damage in polymer solutions. The implications of the results are discussed with respect to the reduction of collateral damage in ultrasound phacoemulsification.

A crucial pre-requisite for quantum information applications is the ability to produce a scalable quantum system that can be controllably manipulated. We present a technique that promises the practical realization of a scalable system with arrays of gated quantum dots (QDs) emitting at wavelengths suitable for fibre based quantum cryptography. We show how the random nature of the nucleation site for self-assembled QDs can be overcome by a nanotemplate deposition technique such that further processing around these dots can be performed. By knowing exactly where the QD is, we position electrostatic gates around the dot with better than 30 nm accuracy. With these gates and a Si n-doped back gate, we demonstrate from both simulation and experiment that we can control the electron number of the dot via vertical electric fields.

The principal objectives of the work reported in this paper were two-fold. Firstly, to assess, by means of the numerical simulation of transverse wave propagation within a linear viscoelastic medium, the degree to which wavegroup propagation involving a finite frequency interval (2Δ ω ) corresponds to an ‘ideal’ beat (i.e. one for which 2Δ ω → 0). Secondly, to compare the results of shear wave propagation measurements with predictions based on a rheometrical theory, which describes the gelation of materials in terms of their wave dispersion characteristics. The results of the numerical simulations indicate that for a sufficiently small value of the frequency interval Δ ω / ω , the nodal and anti-nodal regions of the amplitude modulation envelope of wavegroups propagating within a critical-gel may be defined with sufficient accuracy to permit calculation of the corresponding value of the group velocity U . The results of high frequency shear wave dispersion measurements made on a system known to display critical-gel behaviour provide encouraging agreement with theory and the results of the simulations.

We discuss the preparation and spectroscopic characterisation of a single InAs/InP quantum dot suitable for long-distance quantum key distribution applications around λ=1.55 μm . The dot is prepared using a site-selective growth technique which allows a single dot to be deposited in isolation at a controlled spatial location. Micro-photoluminescence measurements as a function of exciton occupation are used to determine the electronic structure of the dot. Biexciton emission, shell filling and many-body re-normalization effects are observed for the first time in single InAs/InP quantum dots.

We report theoretical and experimental work which demonstrates how the viscoelastic dispersion of shear waves may be exploited in studies of the rheological properties of systems such as 'critical-gels' - systems at the gel point. At the gel point a material undergoing gelation changes, from one in which only short range connectivity is present, to one in which structural self-similarity is sample-spanning. Experiments are described in which marked changes in high-frequency shear-wave dispersion are recorded during the viscoelastic-liquid to viscoelastic solid transition about the gel point. The results accord with theoretical treatments of the sol-gel transition, based on a modified form of the Gross-Marvin network model. We report how this modified model has been used to investigate the interdependence of the high- and low-frequency features of the evolving relaxation time spectra associated with the growth of discrete, mechanically self-similar nodal networks. An analysis of the growth of the networks reveals a scale-invariant characteristic of the underlying gel microstructure and an associated fractal dimension, d f , in the range 1 < d f < 1.8, the maximum value of which corresponds to that reported in computer simulations of cluster-cluster' aggregation processes. The limitations of conventional rheometry in identifying the inner cut-off' length scale of such a fractal characteristic are discussed. Shear wave dispersion measurements are also reported for aqueous dispersions of a synthetic clay colloid which, like the simulated viscoelastic networks, combines the characteristics of high-shear elasticity and low-wave attenuation with a maximum fractal dimension of 1.8.

The incidence of tuberculosis has ceased to decline in the developing world and in some parts of the developed world. This is thought to result mainly from the increased prevalence of human immunodeficiency virus infection and the development of multidrug-resistant strains of Mycobacterium tuberculosis. In addition, it is increasingly presenting in atypical sites and in an atypical manner. However, a high index of suspicion can overcome these diagnostic difficulties and enable early appropriate treatment to produce excellent results. We report a case of isolated tuberculous osteomyelitis of the bones of the hindfoot of a 41-year-old man that proved difficult to diagnose but which responded very well to chemotherapy.

A study of shear wave dispersion in a gelling system shows that marked changes in dispersion occur due to the viscoelastic liquid to viscoelastic solid transition. A theoretical study suggests that an immediate pre-gel combination of liquid-like and solid-like properties might be detected by shear wave dispersion measurements. Experimental work on a system which exhibits critical gel behaviour gives a high frequency wave dispersion in good agreement with theoretical predictions. The work illustrates the interdependence of the development of the relaxation spectrum at low frequencies and the high frequency wave dispersion, and suggests that measurements of the latter might be used to determine the gel-point in some systems.

We discuss the design, fabrication and characterisation of optical microcavities suitable for application with single, site-selected InAs/InP quantum dots emitting around λ =1550 nm. The fabrication procedures that we employ allow high finesse cavities to be constructed around single quantum dots with a known nucleation site and ground state emission energy. Two types of cavity are explored: (i) pillar cavities in which the quantum dot can be located within the semiconductor spacer layer between two dielectric Bragg reflectors and (ii) photonic bandgap cavities employing textured InP membranes. For 1 μm diameter, SiO 2 /Ta 2 O 5 pillar cavities we obtain cavity quality factors, Q , of 1500 and for membrane cavities, Q values of 850.

Fucoidan from Fucus vesiculosus inhibits human sperm-zona pellucida binding and blocks the zona pellucida-induced acrosome reaction in human sperm. Fucoidan also potently inhibits selectin-mediated adhesion of leukocytes to vascular endothelium. To understand the molecular basis for fucoidan's inhibition of specific cell adhesion events, we have investigated the structure of this fucan using definitive methods of carbohydrate structural analysis. We report the revised average structure for fucoidan. [formula: see text] This average structure differs from the previous model for fucoidan in two respects. First, the core region of the fucan is composed primarily of a polymer of alpha 1-3-linked fucose with sulfate groups substituted at the 4 position on some of the fucose residues. Secondly, fucose is also attached to this polymer to form branch points, one for every 2-3 fucose residues within the chain. This revised average structure is consistent with previous studies suggesting a branched random coil as the best model for this polysaccharide. The proposed model is also a closer structural analogue of the sulfated carbohydrate ligands that bind to selectins. This information should be useful for determining whether a relationship exists between selectin-mediated adhesion of leukocytes and human sperm-egg binding.