Are patients admitted to emergency departments with regular supraventricular tachycardia (SVT) treated appropriately?

Regular supraventricular tachycardia (SVT) is frequently encountered in clinical practice. Guidelines are available from the National Service Framework (NSF) for the treatment of patients attending emergency departments (ED) with SVT. These recommend a thyroid-function test (TFT) and arrhythmia electrocardiography (ECG), and referral to a heart-rhythm specialist on discharge. Hospital admission is rarely required. In our multicentre study, we examined the implementation of these guidelines among patients attending the ED with SVT. Only 34% of patients had specialist referrals, with an average wait of 50.3 days (the majority of delays resulted from referral requests from general practitioners). A history of previous SVT, the mode of tachycardia termination, patient age and/or comorbidities were similar for the 27 (23.5%) patients who were admitted overnight. Of these, 15 (13%) of the total 115 patients who attended ED with regular SVT were referred for Holter monitoring despite having ECGs demonstrating arrhythmia. Low referral rates, unnecessary investigations and admissions indicate a need for improvement for better patient care and to minimise healthcare costs. We have formulated a standard operating procedure, which will be available via the College of Emergency Medicine website

Dynamics of Micropollutant Adsorption to Polystyrene Surfaces Probed by Angle-Resolved Second Harmonic Scattering

Angle-resolved second harmonic scattering is used to probe the adsorption dynamics of aqueous cationic and anionic dye molecules onto polystyrene surfaces. The adsorptions of malachite green to negatively charged polystyrene and naphthol yellow S to positively charged polystyrene are both highly favorable, with Î"GAds values of -10.9 ± 0.2 and -10.27 ± 0.09 kcal/mol, respectively. A competitive displacement methodology was employed to obtain values for the adsorption free energies of various smaller neutral organic molecules, including the important micropollutant ascorbic acid, caffeine, and pentoxifylline. For charged adsorbers, electrostatic interactions appear to significantly contribute to adsorption behavior. However, electrostatic repulsion does not necessarily deter the adsorption of molecules with large uncharged moieties (e.g., surfactants). In these cases, the mechanism of adsorption is dominated by van der Waals interactions, with the surface charge playing a relatively minor role

Giant leaps and long excursions: Fluctuation mechanisms in systems with long-range memory

We analyse large deviations of time-averaged quantities in stochastic processes with long-range memory, where the dynamics at time t depends itself on the value q_t of the time-averaged quantity. First we consider the elephant random walk and a Gaussian variant of this model, identifying two mechanisms for unusual fluctuation behaviour, which differ from the Markovian case. In particular, the memory can lead to large deviation principles with reduced speeds, and to non-analytic rate functions. We then explain how the mechanisms operating in these two models are generic for memory-dependent dynamics and show other examples including a non-Markovian symmetric exclusion process.Comment: longer version (16 pages), with more detailed discussio

Fetal-derived trophoblast use the apoptotic cytokine tumor necrosis factor-alpha-related apoptosis-inducing ligand to induce smooth muscle cell death.

Remodeling of the uterine spiral arteries during pregnancy transforms them from high to low resistance vessels that lack vasoconstrictive properties. This process is essential to meet the demand for increased blood flow imposed by the growing fetus. Loss of endothelial and smooth muscle cells (SMC) is evident in remodeled arteries but the mechanisms underlying this transformation remain unknown. This study investigated the hypothesis that fetal trophoblast invading from the placenta instigate remodeling by triggering cell death in vascular SMC. Specifically, a role for trophoblast-derived death inducing cytokine tumor necrosis factor-α–related apoptosis-inducing ligand (TRAIL) was investigated. Expression of the activating TRAIL receptors R1 and R2 was detected by flow cytometry on human aortic SMC and by immunohistochemistry on spiral artery SMC. Recombinant human TRAIL induced human aortic SMC apoptosis, which was inhibited by antibodies against TRAIL-R1 or -R2. Perfusion of denuded spiral artery segments with recombinant human TRAIL also induced SMC apoptosis. Trophoblasts isolated from first trimester placenta expressed membrane-associated TRAIL and induced apoptosis of human aortic SMC; apoptosis was significantly inhibited by a recombinant human TRAIL-R1:Fc construct. Trophoblast within the first trimester placental bed also expressed TRAIL. These data show that: 1) TRAIL causes SMC death; 2) trophoblast produce the apoptotic cytokine TRAIL; and 3) trophoblast induce SMC apoptosis via a TRAIL-dependent mechanism. We conclude that TRAIL produced by trophoblast causes apoptosis of SMC and thus may contribute to SMC loss during spiral artery remodeling in pregnancy

Temperature dependent partition functions and equilibrium constant for HCN and HNC

Ab initio vibration-rotation energy levels are summed to estimate a partition function for the total HCN system. By assigning individual levels to HCN and HNC, separate partition functions are obtained for the isomers. These are used to give a temperature dependent equilibrium constant which suggests that at temperatures typical of cool carbon stars, about 20% of the HCN system is actually HNC. Errors in the partition functions and equilibrium constant are estimated. (C) 2002 American Institute of Physics

Additive manufacturing of physical assets by using ceramic multicomponent extra-terrestrial materials

Powder Bed Fusion (PBF) is a range of advanced manufacturing technologies that can fabricate three-dimensional assets directly from CAD data, on a successive layer-by-layer strategy by using thermal energy, typically from a laser source, to irradiate and fuse particles within a powder bed.The aim of this paper was to investigate the application of this advanced manufacturing technique to process ceramic multicomponent materials into 3D layered structures. The materials used matched those found on the Lunar and Martian surfaces. The indigenous extra-terrestrial Lunar and Martian materials could potentially be used for manufacturing physical assets onsite (i.e., off-world) on future planetary exploration missions and could cover a range of potential applications including: infrastructure, radiation shielding, thermal storage, etc.Two different simulants of the mineralogical and basic properties of Lunar and Martian indigenous materials were used for the purpose of this study and processed with commercially available laser additive manufacturing equipment. The results of the laser processing were investigated and quantified through mechanical hardness testing, optical and scanning electron microscopy, X-ray fluorescence spectroscopy, thermo-gravimetric analysis, spectrometry, and finally X-ray diffraction.The research resulted in the identification of a range of process parameters that resulted in the successful manufacture of three-dimensional components from Lunar and Martian ceramic multicomponent simulant materials. The feasibility of using thermal based additive manufacturing with multi-component ceramic materials has therefore been established, which represents a potential solution to off-world bulk structure manufacture for future human space exploration

The Effect of Ultrasonic Excitation on the Electrical Properties and Microstructure of Printed Electronic Conductive Inks

Abstract: Ultrasonic Additive Manufacturing (UAM) is an advanced manufacturing technique, which enables the embedding of electronic components and interconnections within solid aluminium structures, due to the low temperature encountered during material bonding. In this study, the effects of ultrasonic excitation, caused by the UAM process, on the electrical properties and the microstructure of thermally cured screen printed silver conductive inks were investigated. The electrical resistance and the dimensions of the samples were measured and compared before and after the ultrasonic excitation. The microstructure of excited and unexcited samples was examined using combined Focused Ion Beam and Scanning Electron Microscopy (FIB/SEM) and optical microscopy. The results showed an increase in the resistivity of the silver tracks after the ultrasonic excitation, which was correlated with a change in the microstructure: the size of the silver particles increased after the excitation, suggesting that inter-particle bonding has occurred. The study also highlighted issues with short circuiting between the conductive tracks and the aluminium substrate, which were attributed to the properties of the insulating layer and the inherent roughness of the UAM substrate. However, the reduction in conductivity and observed short circuiting were sufficiently small and rare, which leads to the conclusion that printed conductive tracks can function as interconnects in conjunction with UAM, for the fabrication of novel smart metal components