Percutaneous angioplasty for infrainguinal graft-related stenoses

Objective:To assess the success of percutaneous transluminal angioplasty (PTA) in treating infrainguinal graft-related stenoses.Design:Retrospective analysis of stenoses undergoing PTA over 6 years.Materials:Fifty-seven stenoses in 42 grafts.Methods:Site, length and type of stenoses recorded. Follow-up till discharge, graft occlusion or death.Results:PTA was successful in 48/57 stenoses in 36 grafts (G), with a poor result in seven. Further PTA was required in seven stenoses (7 G). One graft occluded at PTA and one stenosis was inaccessible. Overall graft (G) patency (median 13 months) was 82% (1 year patency 84%). Of 48 successful PTAs (37 G), 36 remained patent (28 G), eight (4 G) occluded and four were lost to follow-up (4 G). Fourteen of thirty-six stenoses which remained patent required further intervention (seven PTA, six jump grafts, one vein patch). The four occlusions were associated with small veins (two), multiple stenoses (one) and a PTFE graft which occluded 10 days following PTA. Of the seven PTAs with a poor angiographic result, five remained patent, three after further intervention.Conclusion:PTA is the best treatment for localised stenoses. Stenoses >2 cm or multiple (three or more) stenoses are best treated surgically. Follow-up is essential, as 20% require further intervention

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Existence of families of spacetimes with a Newtonian limit

J\"urgen Ehlers developed \emph{frame theory} to better understand the relationship between general relativity and Newtonian gravity. Frame theory contains a parameter $\lambda$, which can be thought of as $1/c^2$, where $c$ is the speed of light. By construction, frame theory is equivalent to general relativity for $\lambda >0$, and reduces to Newtonian gravity for $\lambda =0$. Moreover, by setting \ep=\sqrt{\lambda}, frame theory provides a framework to study the Newtonian limit \ep \searrow 0 (i.e. $c\to \infty$). A number of ideas relating to frame theory that were introduced by J\"urgen have subsequently found important applications to the rigorous study of both the Newtonian limit and post-Newtonian expansions. In this article, we review frame theory and discuss, in a non-technical fashion, some of the rigorous results on the Newtonian limit and post-Newtonian expansions that have followed from J\"urgen's work

Importance of surface roughness on the magnetic properties of additively manufactured FeSi thin walls

Thin-walled structures are being used in soft magnetic components manufactured by additive manufacturing to limit eddy current losses in AC machines. Fe-6.5wt %Si has been shown to be a promising material in such components, however most characterisation has taken place using thicker bulk material. Thermal conditions and microstructure have been shown to differ within thin-walled structures, hence magnetic properties may also differ. This study characterises the magnetic properties of thin-walled structures, showing that the 〈001〉 texture usually apparent in laser powder-bed fusion does not persist in thin-walled samples built at an angle to the build platform. Surface roughness (Sa) is shown to increase with build angle from 28 µm when perpendicular to the build platform, to 80 µm when parallel, causing a deterioration in magnetic properties such as susceptibility which is reduced by up to 25 %. Improvements in magnetic properties are demonstrated for samples with lower surface roughness due to improved laser parameters, with even larger improvements available when using polishing as a post-process finishing operation which was shown to improve susceptibility by over 10 %. This study enables the designers of soft magnetic components made by additive manufacturing, the freedom to design magnetic flux paths at any angle in the build chamber and gives surface roughness as a key parameter to improve magnetic properties

Controlling grain structure in metallic additive manufacturing using a versatile, inexpensive process control system

Additive manufacturing (AM), commonly termed 3D printing, is a revolutionary manufacturing technology with great industrial relevance in the aerospace, medical and automotive sectors. Metallic AM allows creation of complex intricate parts and repair of large components; however, certification is currently a concern due to lack of process consistency. A versatile, inexpensive process control system was developed and integrated, reducing variability in melt pool fluctuation and improving microstructural homogeneity of components. Remnant microstructural variation can be explained by the change in heat flow mechanism with geometry. The grain area variability was reduced by up to 94% at a fraction of the cost of a typical thermal camera, with control software written in-house and made publically available. This decreases the barrier to implementation for process feedback control, which can be implemented in many manufacturing processes, from polymer AM to injection moulding to inert-gas heat treatment

Cosmological post-Newtonian expansions to arbitrary order

We prove the existence of a large class of one parameter families of solutions to the Einstein-Euler equations that depend on the singular parameter \ep=v_T/c (0<\ep < \ep_0), where $c$ is the speed of light, and $v_T$ is a typical speed of the gravitating fluid. These solutions are shown to exist on a common spacetime slab M\cong [0,T)\times \Tbb^3, and converge as \ep \searrow 0 to a solution of the cosmological Poisson-Euler equations of Newtonian gravity. Moreover, we establish that these solutions can be expanded in the parameter \ep to any specified order with expansion coefficients that satisfy \ep-independent (nonlocal) symmetric hyperbolic equations

Post-Newtonian expansions for perfect fluids

We prove the existence of a large class of dynamical solutions to the Einstein-Euler equations that have a first post-Newtonian expansion. The results here are based on the elliptic-hyperbolic formulation of the Einstein-Euler equations used in \cite{Oli06}, which contains a singular parameter \ep = v_T/c, where $v_T$ is a characteristic velocity associated with the fluid and $c$ is the speed of light. As in \cite{Oli06}, energy estimates on weighted Sobolev spaces are used to analyze the behavior of solutions to the Einstein-Euler equations in the limit \ep\searrow 0, and to demonstrate the validity of the first post-Newtonian expansion as an approximation

Mechanical properties of stochastically cracked soft magnetic material

Processing of soft magnetic materials with additive manufacturing has shown capability to deliver good magnetic properties and increased silicon content of Fe-6.5 wt%Si, however methods must be used to reduce the eddy currents in large bulk cross-sections in components created by additive manufacturing. Geometrical design has been shown to do this effectively, however stochastically cracked parts show similar magnetic performance with a large increase in stacking factor. To enable their use in electrical machines the mechanical properties of this material must be understood. Therefore, this study uses uniaxial tensile testing to understand the mechanical performance. The ultimate tensile strength of the material in the as-built condition was 17.9 MPa (σ = 4.5 MPa), which was improved by 40% to 25.5 MPa (σ = 5.7 MPa) by infiltrating the cracks with a low viscosity resin. This brings the material strength to more than three standard deviations from the required strength of 7 MPa to be used in a specific axial flux machine. The material exhibited an elongation to failure of 8-10%, showing that the suppression of ordered phases by high cooling rates has improved the ductility of the material. Hence, the stochastically cracked parts have sufficient properties to be used in the 3D magnetic circuits of electrical machines

Utilisation of specialist epilepsy services and antiseizure medication adherence rates in a cohort of people with epilepsy (PWE) accessing emergency care

Background: An epilepsy-related attendance at A&amp;E is associated an increased risk of subsequent death within 6 months. Although further work is required to provide a definitive explanation to account for these findings, in the interim it would seem reasonable that services are designed to ensure timely access and provide support at a time of greatest risk. We aim to determine the frequency of patients accessing specialist neurology services following an epilepsy-related admission/unscheduled care episode and consider ASM adherence at the point of attendance. Methods: Patients were identified retrospectively via the NHS Greater Glasgow and Clyde live integrated epilepsy Dashboard following an unscheduled epilepsy-related admission or A&amp;E attendance between 1st January 2022 and 30th June 2022. We calculated adherence to anti-seizure medication for a period of 6 months prior to admission and defined poor medication adherence as a medication possession ratio of less than 80%. We evaluated the rate of any outpatient neurology clinic attendance in the subsequent 3, 6 and 12 months following an epilepsy-related unscheduled care episode. Additional clinical information was identified via the electronic patient records. Results: Between 1st Jan 2022 and 30th June 2022, there were 266 emergency care seizure-related attendances. The mean age at attendance was 46 years (range: 16-91). Most of PWE were males (63%) and 37% were females. Epilepsy classification-29.3% had GGE, 41.7 % had focal epilepsy, and in 29% of cases the epilepsy was unclassified. Of the admissions, 107/ 266 (40.2%) generated follow-up within 6 months of attendance. Poor medication adherence was noted in 54/266 (20.3%). 28.2% of cases had input from on-call neurology service during admission/ED attendance, and of those 60% had ASM adjusted. 18% of attendances had a background diagnosis of learning disability. One-third of attendances of PWE had a history of mental health disorder 35% (93/266). 25% of ED attendances noted an active history of alcohol consumption misuse or/and recreational drug use. 14 (5.5%) of PWE died during the period of interest (12 months following the last ED visit). In 6/14 (42.3%) death was associated with poor medication adherence. Conclusion: This study demonstrates that a significant proportion of patients who experienced seizure-related admissions/ attendance did not access specialist neurology services in a timely manner. In addition, poor medication adherence remains a problem for a substantial number of people living with epilepsy. Early access to specialist services may go some way to improving care and reducing excessive mortality in PWE by allowing anti-seizure medication to be titrated and poor medication adherence to be addressed in those at greatest risk

L-VRAP-a lunar volatile resources analysis package for lunar exploration

The Lunar Volatile Resources Analysis Package (L-VRAP) has been conceived to deliver some of the objectives of the proposed Lunar Lander mission currently being studied by the European Space Agency. The purpose of the mission is to demonstrate and develop capability; the impetus is very much driven by a desire to lay the foundations for future human exploration of the Moon. Thus, LVRAP has design goals that consider lunar volatiles from the perspective of both their innate scientific interest and also their potential for in situ utilisation as a resource. The device is a dual mass spectrometer system and is capable of meeting the requirements of the mission with respect to detection, quantification and characterisation of volatiles. Through the use of appropriate sampling techniques, volatiles from either the regolith or atmosphere (exosphere) can be analysed. Furthermore, since L-VRAP has the capacity to determine isotopic compositions, it should be possible for the instrument to determine the sources of the volatiles that are found on the Moon (be they lunar per se, extra-lunar, or contaminants imparted by the mission itself