Search

Photonics-based quantum information technologies require efficient, high emission rate sources of single photons. Position-controlled quantum dots embedded within a broadband nanowire waveguide provide a fully scalable route to fabricating highly efficient single-photon sources. However, emission rates for single-photon devices are limited by radiative recombination lifetimes. Here, we demonstrate a multiplexed single-photon source based on a multidot nanowire. Using epitaxially grown nanowires, we incorporate multiple energy-tuned dots, each optimally positioned within the nanowire waveguide, providing single photons with high efficiency. This linear scaling of the single-photon emission rate with number of emitters is demonstrated using a five-dot nanowire with an average multiphoton emission probability of

BACKGROUND: The acute vascular disease deep vein thrombosis (DVT) requires oral anticoagulants to prevent progression. Monitoring therapeutic efficacy of direct oral anticoagulants (DOAC), including rivaroxaban, is problematic as no reliable test is available. Advances in rheometry have led to the development of a functional coagulation biomarker using Gel Point (GP) analysis which assesses clot structure formation. The biomarker measures incipient clot formation time (TGP) and quantifies fibrin clot structure in terms of fractal dimension (df). OBJECTIVE: This study aimed to investigate clot structure formation in first time DVT and the effect of rivaroxaban treatment. METHODS: This prospective observational cohort study measured the GP and standard laboratory markers at three sample points: pre-treatment and at 20 and 60 days following 15 mg BD and 20 mg OD rivaroxaban respectively. RESULTS: Forty DVT patients (mean age 64 years [SD±14.8]; 23 males, 17 female) were recruited. The results show that DVT vs non-DVT patients did not have a significantly different GP profile (df: 1.72±0.06 vs 1.70±0.06 and TGP: 267±68 sec vs 262±73 sec) with both within the defined healthy index. In addition, rivaroxaban therapy increased TGP to 392 s (±135 s) after 20 days, and subsequently increased to 395 s (±194 s) at 60 days but did not significantly increase df (from 1.69±0.05 to 1.71±0.06). CONCLUSIONS: The results indicate in this cohort of DVT patients there was no underlying hypercoagulable effect as determined by gel point analysis. Furthermore, the anticoagulant effect of rivaroxaban prolonged clotting, suggesting a protective effect against clot formation, without significantly reducing clot microstructural properties.

HypothesisOur central hypothesis is that inhibition of Schwann cell de-differentiation, in the post-injury setting, will reduce synkinesis and improve facial muscle functionBackgroundNo therapies exist to improve the accuracy of facial nerve regeneration. Following peripheral nerve injury, adult reactive Schwann cells de-differentiate and express glial fibrillary acidic protein (GFAP); suggesting that reactive Schwann cells impact axonal regeneration precision.MethodsTransgenic GFAP-thymidine kinase (TK) mouse model was employed, allowing selective downregulation of reactive GFAP expressing Schwann cells on exposure of 7 day osmotic pump delivery of ganciclovir. Adult female transgenic GFAP-TK mice had right facial nerve transected and then immediately repaired with tissue glue, they then either were treated with saline or ganciclovir (GCV). At 6 weeks post-injury, mice were exposed to random air puffs events while high speed videography recorded whisker and eye movement. MatLab code video processing with publicly available BIOTACT algorithm automatically tracked whiskers.ResultsWhisker velocity was calculated using binning statistical analysis. Saline treated animals confirmed our model’s ability to detect aberrant movement such that intact (left) facial nerves caused whisker protraction, while repaired (right) facial nerves had retraction. Administration of GCV increased whisker retraction compared to saline. GCV did not impact intact animal whisker movement compared to repaired whiskers.ConclusionsInhibition of reactive Schwann cell proliferation appears to worse the degree of synkinesis, providing important insight into a potential therapeutic target for facial nerve injury.

Results of numerical modeling of the interaction of an electron beam propagating across relativistic plasma waves indicate that electron beam filamentation and focusing may occur under certain conditions. The model is based on solving the relativistic equation of motion in three dimensions for the individual electrons in a tenuous Gaussian beam, as they pass through a relativistic plasma wave. Several electron beam and plasma wave parameters were varied, and the results are summarized. One of the results is that the spacing of the electron beam filaments correlates with the wavelength of the plasma wave. The electron beam filaments appear as vertical slabs after the beam exits the plasma waves. The electron beam also compresses to a focus after it exits the plasma, and the focal distance depends on several parameters including the electron beam energy and phase velocity of the relativistic plasma wave. It is suggested that these focusing and filamentation phenomena may be the basis for diagnostics schemes for laser plasma interactions. The parameters used in the model were electron beam energies in the 5–50 keV range and plasma wave properties typical for the beat-wave produced by CO2 lasers, which correspond to the facilities available in our laboratory. The limitations of these results to lower energy density beam and plasma regimes and to higher energy density regimes will be discussed.

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

Background The long term benefits of exercise on the cardiovascular status of a patient have been proven, however, their benefit/risk relationship with exercise intensity is unclear. Furthermore, many thromboembolic diseases such as myocardial infarction and ischaemic stroke are associated with profound catecholamine release. In this study we explore the relationship between catecholamine release and hemodynamic changes and their effect on coagulation. Materials and methods Twelve healthy recreationally active males were recruited. Local anesthesia was given and catheters were placed under aseptic conditions, in the femoral artery and vein of the experimental leg. The first experiment involved tyramine infusion into the femoral artery at a dose of 1.0 μmol·min−1·L leg volume−1. The second experiment involved single leg knee-extensor exercise performed at 30 W for 15 min. Venous blood was collected at each time point to assess clot microstructure using the df biomarker. Results and conclusions Tyramine infusion causes a local noradrenaline release in the leg. The increase in noradrenaline was associated with a significant increase in clot microstructure formation (df increased from 1.692 ± 0.029 to 1.722 ± 0.047, p = 0.016). Additionally moderate intensity single leg knee extensor exercise, which minimally alters sympathetic activity, also induced an increases in df (from 1.688 ± 0.025 to 1.723 ± 0.023, p = 0.001). This suggests that exercise can alter clot microstructure formation both via an increase in catecholeamine levels and by factors related to muscle activity per se, such as increased blood flow and consequent shear. These findings have implications for recommendations of exercise in patients at risk of cardiovascular events.

The study purpose was to define changes in coagulation across the sepsis spectrum using rotational thromboelastometry (ROTEM).Sepsis patients were recruited on admission to the Emergency Department and Intensive Care Units of a large teaching hospital in Wales. ROTEM markers of clot development and fibrinolysis were determined, as well as standard coagulation markers. A healthy control group matched for age and gender was also recruited (n=44).100 patients were recruited (50 sepsis, 20 severe sepsis and 30 septic shock). Maximum clot firmness was significantly higher in the sepsis (p0.001) and severe sepsis (p=0.012) groups than the healthy control (71.6±4.5 and 70.4±4.1 vs 64.4 respectively). In septic shock there was prolonged clot development; however, maximum clot firmness remained normal. Fibrinolytic function was significantly impaired in septic shock, which was also significantly associated with 28-day mortality (p0.001).ROTEM indicated significantly enhanced clot structural development in sepsis and severe sepsis, which could be indicative of a hypercoagulable phase. In septic shock, despite there being a prolongation of clotting pathways and impaired fibrinolysis, clot mass was comparably normal, suggestive of the development of a clot with healthy characteristics.

Nanoblending hydrophilic nanofillers thoroughly into hydrophobic polymer matrices has long been challenging, especially if involving no pre-functionalization on a 1D ceramic nanomaterial. Here we report a facile approach to fine-tuning of sodium titanate (Na2Ti3O7) nanobelt’s (NB) surface chemistry widely by exchanging the NB’s crystal lattice cations, for successfully nanoblending the low-cost and versatile NBs into the poly(vinyl benzyl chloride) or p(VBC) and the sulfonated form of pVBC’s [or sp(VBC)] matrixes. For the first time, the adjustable nanocompositing showed a long-sought workability in not only in situ radical polymerization of VBC monomer but also ex situ nanoblending of the p(VBC), with the NBs. The resultant nanocomposites possess an unusual surface versatility that can be tailored from being hydrophilic to being hydrophobic by design. This method concludes a generalized and industry-viable approach to mass-producing nanocomposites of many types facilely at low-cost, especially for large scale industries such as packaging materials.

There has recently been an increase in popularity of the direct anterior approach (DAA) hip arthroplasty, due to the muscle sparing nature of its interneural intervals, with the innominate tubercle being used as a lateral reference point for the femoral neck osteotomy. However, there is very little information in the literature on this rather enigmatic structure, with no evidence as to whether it is a consistent and reliable marker, or if it varies significantly in the population. In this study, data were gathered from 79 pairs of adult, post-medieval skeletal femora to investigate the effects of sex, age, femoral side, femoral length, femoral neck length, and femoral neck-shaft angle on the width, length, and height of the innominate tubercle. The sex, age, and date of death of the individuals had been recorded. Statistical analysis included canonical correlation and multivariate multiple regression. We found that there was no statistical significance or correlation between the width, length, or height of the tubercle with respect to any of the variables investigated. These results suggest that the innominate tubercle does not differ markedly between individuals in the Caucasian population, and, is therefore, a reliable landmark for femoral neck osteotomy during DAA hip arthroplasty. We present what we believe to be a definitive survey of the variability of the innominate tubercle in a Caucasian population. Clin. Anat. 30:578-584, 2017. © 2017 Wiley Periodicals, Inc.

We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125±18nm (PEO) and 1.58±0.28μm (PVP); Free-surface electrospun: 155±31nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8±3nm to 27±5nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique.

Sepsis and its progression are known to have a major influence on the coagulation system. Current coagulation tests are of limited use when assessing coagulation in sepsis patients. This study aims to assess the potential for a new functional biomarker of clot microstructure, fractal dimension, to identify changes in the mechanical properties of clot microstructure across the sepsis spectrum (sepsis, severe sepsis and septic shock). A total of 100 patients that presented acutely to a large teaching hospital were included in this prospective observational study (50 sepsis, 20 severe sepsis and 30 septic shock) against a matched control of 44 healthy volunteers. Fractal analysis was performed, as well as standard markers of coagulation, and six plasma markers of inflammation. Fractal dimension was significantly higher in the sepsis and severe sepsis groups than the healthy control (1.78 ± 0.07 and 1.80 ± 0.05, respectively vs 1.74 ± 0.03) (p

A description is given of the terahertz beamline and tissue culture facility that is being commissioned on the ALICE accelerator at the Daresbury laboratory

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.

Photoluminescence from individual InAs/InP quantum dots embedded within a planar n–i structure is studied as a function of vertical electric field. We demonstrate control of the electron number and determine the Stark shift and built-in dipole at zero electric field. In contrast to the well studied InAs/GaAs quantum dot material system, we obtain a built-in dipole which indicates that the electron lies above the hole at zero electric field. The magnitude and direction of the measured dipole suggests a uniform quantum dot composition. The gating principles we demonstrate can be applied to pre-positioned InAs/InP quantum dots, such that arrays of initialized single spins can be employed for quantum information applications. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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 resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s – Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media.

In this study, modelling of network-structured material flow is considered through a rounded-corner, hyperbolic 4:1:4 contraction–expansion geometry, under axisymmetric configuration. Three representative constitutive models are adopted to represent networked behaviour and to investigate the flow of wormlike micellar fluids in this context. This includes the modified Bautista–Manero (MBM) model (for base thixotropic properties), some newly proposed micellar models (NM_τ p and NM_T; for advanced thixotropic modelling), and the EPPT model (for contrast against non-thixotropic properties). In this configuration, emphasis is placed upon interpretation of flow behaviour for these constitutive models, against their response in simple rheometrical flows. To best determine the factors that contribute to epd prediction, current findings have also been contrasted against those reported earlier in Lopez-Aguilar et al. (J Non-Newtonian Fluid Mech 204:7–21, 2014), for the counterpart abrupt rounded-corner, axisymmetric 4:1:4 contraction–expansion flow.

The main focus of the present computational modelling work is to determine the extensional rheological response of some model biofluids, with a view to ultimately aiding experimentally based analyses and clinical practice. This is accomplished in the present study through model extensional flows and rheological investigation, addressing filament stretching and contraction flows, and upon which significant advances are presented. As such, two biofluid flow systems within the human body are of current interest: (i) respiratory disorders and sputum in the lung airways (associated with filament stretching), where stretchiness of mucus sputum in situ is vital, with clinical focus on chronic obstructive pulmonary disease (COPD/sputum); and (ii) bile flow in the biliary system (contraction flow), with clinical focus on disorders of primary sclerosis cholangitis and common bile duct narrowing. Both sputum and bile biofluid systems are represented through kinetic theory rheological fluid modelling, with capability to represent material structure entanglement, branching and anisotropy. This is practically achieved by appealing to the class of pom-pom differential constitutive models, extracted from polymer melt physics and deployed here through a single extended pom-pom (SXPP) approximation. This class of models is sufficiently rich to enable description of both network structure and rheological properties, exhibiting viscoelastic response (memory), with strain-hardening/softening and shear-thinning properties.

Objectives. Work-related upper limb disorders (WRULD) are common and disabling complaints in industry, but a tissue diagnosis can be difficult where the pain is diffuse and variable, and this prevents effective treatment. Diffuse arm pain is frequently found in those doing rapid or strenuous repetitive work, such as factory assembly workers or keyboard operators. Similar symptoms occur in the legs in athletes, where chronic compartment syndrome (CCS) is a recognized entity, so we investigated the possibility that this might also be caused by prolonged repetitive work. Methods. Patients were selected if they were unable to continue with work because of chronic forearm pain. They were divided into three groups: 42 patients with symptoms consistent with CCS as defined in the text, 15 volunteers and patients with other arm complaints, and 10 asymptomatic arms of patients with unilateral CCS. We measured the pressure inside the extensor muscle compartment of the forearm at rest and after a 2 min repetitive gripping exercise using an electronic pressure-sensitive probe. Results. The results show that CCS is a common and disabling forearm complaint associated with prolonged repetitive work. Fifteen patients have now had decompressive surgery on the extensor muscle compartment with good relief of symptoms. Conclusion. CCS is responsible for chronic peripheral neurological dysfunction in addition to muscle pain, and awareness of this diagnosis allows early identification and treatment of a currently unrecognized disorder with potential resolution of a long-lasting arm disability.

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 report measurements of the effective tensile strength Fc of commercial “multigrade” oils (in the SAE viscosity grades 5W-30 and 10W-40) over a range of temperatures T, which are representative of those encountered under their normal operating conditions (in the range 20°C⩽T⩽140°C). Also reported are the values of Fc that are obtained for Newtonian silicone oils over a range of shear viscosities. In the experiments reported herein, samples of liquid are subjected to dynamic stressing by a pressure-tension cycle, this being a feature of the conditions experienced by a lubricant within a dynamically loaded journal bearing and the method used to estimate Fc avoids reliance on direct measurements of substantial dynamic tensions using conventional pressure transducers.

This paper discusses the differences between the results of various measurements of the effective tensile strength (F c ) of liquids in experiments involving a pulse of tension (‘negative pressure’) created by the reflection of a pressure pulse at a boundary. Using a modified ‘bullet-piston’ (B-P) pulse reflection apparatus, measurements presented herein show that degassed, deionized water is capable of sustaining tensions an order of magnitude greater than previously reported in B-P work. Results are also reported for a series of Newtonian silicone oils which show a similar dependence of F c on the shear viscosity (μ) as a previous study though the absolute values of F c are greater.

An experimental study is reported of liquid jets formed by the collapse of bubbles under cavitation-generated pressure waves. The results reveal that jets formed from samples of commercial multigrade engine oils experience an extensional flow which is characterized by high rates of extension, the latter being relevant to considerations of the flow of oils within dynamically loaded journal bearings. Contrary to previous indications in the literature, commercial multigrade oils are found to exhibit significantly larger resistance to extensional flow than their Newtonian counterparts and, insofar as the multigrade oils studied here are made viscoelastic by polymer additives and evidently possess significant levels of resistance to extension, the results provide evidence in support of a mitigating effect of viscoelasticity on a cavitation damage related mechanism, as mooted by Berker, Bouldin, Kleis and Van Arnsdale.

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.

This paper reports the first measurements of the effective tensile strength (or ‘cavitation threshold’) Fc, of degassed samples of a commercial multigrade engine oil over a range of temperatures, T, which are representative of those encountered under normal automotive engine operating conditions (in the range 20° C ≤ T ≤ 140°C). Also reported are the values of Fc obtained for Newtonian silicone oils over a range of shear viscosities. In the experiments reported herein, samples of liquid are subjected to dynamic stressing by a rapid pressure—tension cycle, this being a feature of the conditions experienced by an engine oil within a dynamically loaded journal bearing. The method used herein to estimate Fc avoids reliance upon direct measurements of substantial dynamic negative pressures using transducers which are designed for use in the range of positive pressures.

Suicide prevention remains an important objective for the mental health services. The mentally ill represent a group of individuals at increased risk of suicide and, understandably, efforts have been made to ensure high quality care provision to prevent such acts. Audit of clinical practice is an important tool to monitor the efficacy of services and to improve their performance, and here the workings of a multidisciplinary suicide audit process within an inner city general mental health service are described.

This paper addresses discrepancies between the results of different measurements of the effective tensile strength (Fc) of liquids, in experiments in which a pulse of tension (or `negative pressure') is created by the reflection of a pressure pulse at a suitable boundary. We show that a key feature of the pressure records previously reported in such experiments may have been misinterpreted. The first complete account of such pressure records reported here offers an explanation for the order-of-magnitude discrepancies in Fc which arise in work involving instruments such as the `Bullet-Piston' (B-P) pulse-reflection apparatus (Temperley H N V and Trevena D H 1987 J. Phys. D: Appl. Phys. 20 1080). We also report a new method of estimating Fc in a modified B-P apparatus and the results obtained indicate that samples of degassed, deionized water can sustain tensions which are an order-of-magnitude greater than previously reported in B-P work. Results are also reported for work involving samples of Newtonian silicone oils, for which the dependence of Fc on shear viscosity, µ, found in this work confirms that of an earlier study although the absolute values of Fc are found to be considerably greater than previously reported.

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.

We report the management of the acquired claw-toe deformity in ten adults. Each patient developed a varying number of claw toes at a mean interval of six months after the time of injury. There was clinical evidence of an acute compartment syndrome in one case. The clawing occurred at the start of heel-rise in the stance phase of gait. At this stage the patients complained of increasing pain and pressure on the tips of the toes. The deformities were corrected by lengthening flexor hallucis longus and flexor digitorum longus alone or in combination. The presence of variable intertendinous digitations between the tendons of flexor hallucis longus and flexor digitorum longus means that in some cases release of flexor hallucis longus alone may correct clawing of lesser toes.

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.

We provide an explanation for the anomalously low values of liquid tensile strength recorded in some experiments involving the reflection of a pressure pulse (as tension) at the free surface of a column of water, or at a flexible membrane. The present work, which involves a development of the ‘bullet–piston’ method of subjecting a liquid to tension, reconciles previous dynamic stressing results with those obtained for water in a steel Berthelot tube under static stressing. It is shown that the anomalously low values of liquid tensile strength cannot be explained in terms of the effect of the free–surface transition layer in pulse reflection (as was previously thought) but may be attributed to deficiencies in the techniques previously used to record dynamic tensions.

A study of viscoelastic shear wave dispersion in a simulated gelation process involving mechanically self-similar nodal networks is reported. The network formed at the gel point (the infinite network cluster, or `critical gel') shares a common structural feature of smaller network clusters and the onset of a recognizably `gel-like' feature is shown to occur when the characteristic wavelength of the network cluster becomes twice that of an individual node. It is shown that, during gelation, the dispersion of shear waves can be exploited to assess the proximity of a system to an equivalent `critical gel' state at any single frequency, thereby identifying the smallest length scale at which gel-like characteristics are established prior to the gel point. In this way, and for the first time, a rheometrical basis is established for examining the gel-like, self-similar characteristics of pre-gel point viscoelastic liquid systems, in terms of the gel equation but in the absence of a frequency-independent loss tangent. Experiments are reported for a critical gel in which the high-frequency wave dispersion is in good agreement with theory.

The index of refraction for pseudomorphic Si/sub 1-x/Ge/sub x/ layers grown on Si has been measured at wavelengths /spl lambda/=1310 mn and /spl lambda/=1550 nm. The refractive index values were obtained from waveguide mode profile measurements on a series of Si-Si/sub 1-x/Ge/sub x/-Si waveguides with Ge/sub x/ concentrations between x=0.01 and x=0.1. The index of refraction, n, is significantly larger for light polarized parallel to the growth direction than for light polarized in the plane of the epilayer. This birefringence is consistent with the anisotropic index change predicted using photoelastic theory, given the biaxial strain present in the pseudomorphic Si/sub 1-x/Ge/sub x/ layers. At all wavelengths and polarizations, n varies linearly with the Ge concentration. The pseudomorphic Si/sub 1-x/Ge/sub x/ waveguides layer are stable against lattice relaxation during short anneals at 950/spl deg/C, but exhibit partial relaxation after annealing at 1200/spl deg/C.

Male Sprague-Dawley rats (200–250 g) were segregated into 12 groups (n =5). Six groups were injected with morphine sulphate (10,20,30,50 mg/kg,ip) on days 1, 2, 3 and 4 respectively. The specified dose of morphine was given in two divided doses daily at 1000 h (light) and 2200 h (dark) for four consecutive days. The remaining six groups received saline. On day 5, the rats from saline and morphine treated groups were injected with naloxone (50 mg/kg, ip) at 0600 h, 1000 h, 1400 h, 1800 h, 2200 h, or 0200 h to precipitate the withdrawal signs during the light and dark phases of the 24 h period. Withdrawal signs were monitored for the following 30 min. Diarrhea, tremor, teeth chattering and crying (vocalization) were exhibited exclusively by the morphine-dependent rats. Escape attempts and restless activity were observed mostly in morphine-dependent groups, except for a limited response by controls at 0200 h or 0600 h. The percentage response of other signs such as hunch-back posture, piloerection, stereotyp...

A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a shock wave and a turbulent ionized gas. Even though the gas is apparently brought to rest by the shock wave, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters.

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.

DE-1 measurements of ion outflows at E = 5 eV to 32 keV in the Northern Hemisphere outer plasmasphere are compiled in graphs and investigated statistically. The data comprise 40 dayside (6:00-12:00 magnetic local time) and 50 nightside (18:00-23:00) passages at magnetic activities Kp = 0-7 and include six magnetic storms and recoveries as well as quiet periods. Features noted include enhanced number fluxes during periods of increased magnetic activity, upward dayside and downward nightside flows, peak net H(+) fluxes greater than 10 to the 8th/sq cm sec, and greater field-aligned flows (but at lower ion temperatures) in the outer plasmasphere than in the plasma trough.

In this report, we present data on an InGaAs/GaAs strained single quantum well laser with the lowest reported threshold current density to date, namely 44 A cm−2 for a 3 mm cavity length. This was grown by solid-source molecular-beam epitaxy with the arsenic dimer, As2. The structure is that of a graded-index, separate-confinement heterostructure with a single strained InGaAs quantum well, sandwiched between GaAs barrier layers and AlGaAs cladding layers. The wavelength of the lasers was around 985 nm, and the internal efficiency and losses were 69% and 0.70 cm−1, respectively. In addition, data on the uniformity of our lasers, which are grown on rotating 2 in substrates (1 in = 2.54 cm), show drops in photoluminescence emission wavelength and layer thickness of less than 4 nm and 4%, respectively, from the centre to the edge of the wafer and very little compositional change.

Patients with rheumatoid arthritis who underwent excision of the distal ulna were reviewed and the operated wrist was compared with the non-operated side in the 40 patients who had the procedure performed unilaterally. Radiological assessment showed that the radiocapitate measurement of carpal translocation was the most consistent and that excision of the distal ulna was not associated with statistically significant collapse, ulnar translocation or radial rotation of the carpus. 61% of wrists spontaneously developed a radial shelf or limited radiocarpal fusion following excision of the distal ulna, compared to 21% of non-operated wrists. However, there was no statistically significant difference in carpal collapse or ulnar translocation between these two groups.

A 1-year-old female infant presented with a large 7-8 cm Ewing's sarcoma of the left parietal calvarium. It deeply indented the subjacent hemisphere. Wide surgical excision was followed by chemotherapy but not radiation. The patient was clinically free of tumor when she expired 9 months later of sepsis. Though primary Ewing's sarcoma of the skull is said to be relatively rare, we have tabulated 37 cases of this disorder, including the present one (we excluded mandibular tumors (> 100 cases) since they are not usually treated by neurosurgeons). The mean age was 11 years and of those available to follow-up, three quarters were tumor-free 6 months to 7 years postsurgery. The remainder survived an average of 21 months. Ewing's tumors of the calvarium generally grant a favorable prognosis following surgery and/or radiation and chemotherapy. Those at the base of the brain may be more difficult to eradicate. In addition to primary Ewing's tumors, metastases to the skull and the brain from other primary sources in the skeleton have been documented in several reports.

While reading an orthopaedic text you find a table that states rib fractures are highly specific for non-accidental injury in children. No papers are referenced and you wonder what evidence exists to support this statement. ### Structured clinical question In children undergoing chest radiography [patients] are rib fractures on plain radiographs [test] specific for non-accidental injury [outcome]? ### Search strategy and outcome #### Secondary sources Cochrane: rib fractures and non-accidental injury; no relevant reviews found. #### Primary sources Medline (including Medline corrections) 1966–01/02/2004. [(Validated paediatric search filter (March 2003) for Ovid1) AND (exp Child Abuse or non-accidental injury.mp or child abuse$.mp or deliberate injury.mp or exp. domestic violence or child abuse, sexual or exp. Munchausen syndrome by proxy or exp torture or domestic violence.mp or Munchausen syndrome by proxy.mp. or torture.mp or non-accidental injuries.mp) and (exp.rib fractures or rib fracture$.mp or posterior rib fracture$.mp or multiple rib fracture$.mp or bilateral rib fracture$.mp or exp. thoracic injuries or thoracic injury.mp or chostochondral junction injuries.mp)] limited to human and English Language. A total of 113 papers were identified; 105 were of insufficient quality for inclusion or irrelevant. One paper was subsequently excluded …