Portable dynamic fundus instrument

A portable diagnostic image analysis instrument is disclosed for retinal funduscopy in which an eye fundus image is optically processed by a lens system to a charge coupled device (CCD) which produces recordable and viewable output data and is simultaneously viewable on an electronic view finder. The fundus image is processed to develop a representation of the vessel or vessels from the output data

Solid-state graft copolymer electrolytes for lithium battery applications

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point ( < 80 °C), flammable, and volatile organic electrolytes. These organic based electrolyte systems are viable at ambient temperatures, but require a cooling system to ensure that temperatures do not exceed 80 °C. These cooling systems tend to increase battery costs and can malfunction which can lead to battery malfunction and explosions, thus endangering human life. Increases in petroleum prices lead to a huge demand for safe, electric hybrid vehicles that are more economically viable to operate as oil prices continue to rise. Existing organic based electrolytes used in lithium ion batteries are not applicable to high temperature automotive applications. A safer alternative to organic electrolytes is solid polymer electrolytes. This work will highlight the synthesis for a graft copolymer electrolyte (GCE) poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). The conduction mechanism has been discussed and it has been demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence. Batteries containing commercially available LP30 organic (LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) at a 1:1 ratio) and GCE were cycled at ambient temperature. It was found that at ambient temperature, the batteries containing GCE showed a greater overpotential when compared to LP30 electrolyte. However at temperatures greater than 60 °C, the GCE cell exhibited much lower overpotential due to fast polymer electrolyte conductivity and nearly the full theoretical specific capacity of 170 mAh/g was accessed

The Role of Demographic Characteristics in Health Care Strategic Security Planning

The purpose of this paper is to foster understanding of the perception of members in healthcare organizations concerning three specific dimensions in the realm of security: strategic planning for security, proactive initiatives for security controls, and training preparedness for security perspective within the context of HIPAA compliance. The research data was collected using a survey instrument with 43 items of demographic information. The data collected was analyzed using demographic characteristics such as age, gender, education and relevant work experience. The aim of the analysis is to assess whether any significant differences exist between groups regarding the perception of security strategic planning, proactive initiatives and training issues. The statistical results are presented in tabular form with descriptive analysis applied to each of the categories. Data-based conclusions are drawn and future research directions are indicated and discussed

The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking

Background Robotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing of positive prosthesis push-off work in isolation and measure the effects on energetics, mechanics and muscle activity. Methods We tested 10 able-bodied participants walking on a treadmill at 1.25 m · s−1. Participants wore a tethered ankle-foot prosthesis emulator on one leg using a rigid boot adapter. We programmed the prosthesis to apply torque bursts that began between 46% and 56% of stride in different conditions. We iteratively adjusted torque magnitude to maintain constant net positive push-off work. Results When push-off began at or after leading leg contact, metabolic rate was about 10% lower than in a condition with Spring-like prosthesis behavior. When push-off began before leading leg contact, metabolic rate was not different from the Spring-like condition. Early push-off led to increased prosthesis-side vastus medialis and biceps femoris activity during push-off and increased variability in step length and prosthesis loading during push-off. Prosthesis push-off timing had no influence on intact-side leg center-of-mass collision work. Conclusions Prosthesis push-off timing, isolated from push-off work, strongly affected metabolic rate, with optimal timing at or after intact-side heel contact. Increased thigh muscle activation and increased human variability appear to have caused the lack of reduction in metabolic rate when push-off was provided too early. Optimal timing with respect to opposite heel contact was not different from normal walking, but the trends in metabolic rate and center-of-mass mechanics were not consistent with simple model predictions. Optimal push-off timing should also be characterized for individuals with amputation, since meaningful benefits might be realized with improved timing

Pan-genomic analysis to redefine species and subspecies based on quantum discontinuous variation: the Klebsiella paradigm

International audienceBackground: Various methods are currently used to define species and are based on the phylogenetic marker 16S ribosomal RNA gene sequence, DNA-DNA hybridization and DNA GC content. However, these are restricted genetic tools and showed significant limitations. Results: In this work, we describe an alternative method to build taxonomy by analyzing the pan-genome composition of different species of the Klebsiella genus. Klebsiella species are Gram-negative bacilli belonging to the large Enterobacteriaceae family. Interestingly, when comparing the core/pan-genome ratio; we found a clear discontinuous variation that can define a new species. Conclusions: Using this pan-genomic approach, we showed that Klebsiella pneumoniae subsp. ozaenae and Klebsiella pneumoniae subsp. rhinoscleromatis are species of the Klebsiella genus, rather than subspecies of Klebsiella pneumoniae. This pan-genomic analysis, helped to develop a new tool for defining species introducing a quantic perspective for taxonomy

Second Overtone Pulsators Among Delta Scuti Stars

We investigate the modal stability of stellar models at masses and luminosity levels corresponding to post main sequence luminous delta scuti pulsators. The envelope models have been computed at fixed mass value, luminosity level and chemical composition (Y=0.28, Z=0.02). According to a nonlinear approach to radial oscillations the present investigation predicts the occurrence of stable second overtone pulsators for the first time. The shape of both light and velocity curves are presented and discussed, providing a useful tool for the identification of second overtone pulsators among the known groups of radially pulsating stars. The period ratios of mixed mode pulsators obtained by perturbing the first and the second overtone radial eigenfunctions are in agreement with observative values. Finally, the physical structure and the dynamical properties of second overtone pulsators are discussed in detail. The role played by the nodal lines in the destabilization of second overtone pulsators is also pointed out.Comment: 20 pages, 11 Postscript figures, uses aaspp4.sty and tighten.st

Dissociation of the diurnal variation of aldosterone and cortisol in anephric subjects

Dissociation of the diurnal variation of aldosterone and cortisol in anephric subjects. Diurnal variation of plasma aldosterone and cortisol concentration in man was studied in 13 anephric subjects and 7 normal subjects. All subjects were ambulatory and active throughout the study except during an 8-hour sleep period. Six anephric subjects received Kayexalate® (sodium polystyrene sulfonate) during the studies to prevent potassium accumulation and increase in plasma potassium concentration. Diurnal variation of plasma aldosterone concentration with peak and nadir concentrations at 12:00 noon and 12:00 midnight respectively was demonstrated in the studies on normal subjects. Changes in plasma aldosterone concentration were not significantly correlated with changes in plasma cortisol concentration but were highly correlated with changes in PRA (P < 0.001). There was a highly significant correlation between plasma aldosterone and potassium concentration in the anephric subjects studied without Kayexalate® administration (P < 0.001). In the anephric subjects who received Kayexalate®, plasma aldosterone and potassium concentration remained stable, and no correlation could be demonstrated. No diurnal variation of plasma aldosterone concentration could be demonstrated in either group of anephric subjects, whereas plasma cortisol concentration varied as in the studies on normal subjects. Conclusion. Diurnal variation of plasma aldosterone concentration is dependent on continued stimulation by the renin-angiotensin system. Loss of this stimulation has no demonstrable effect on the diurnal variation of plasma cortisol concentration.Dissociation des variations nycthémérales de l'aldostérone et du cortisol chez les sujets anéphriques. Les variations nycthémérales de l'aldostérone et du cortisol plasmatiques chez l'homme ont été étudiées chez 13 sujets anéphriques et 7 sujets normaux. Tous les sujets étaient ambulatoires excepté pendant une période de sommeil de 8 heures. Six sujets anéphriques receivaient du Kayexalate® (sodium polystyrene sulfonate) afin d'empêcher une accumulation de potassium et une augmentation de la kaliémie. Des variations nycthémérales de l'aldostéronémie avec un pic et un nadir à midi et minuit, respectivement, ont été observées chez les sujets normaux. Les modifications de l'aldostéronémie ne sont pas significativement corrélées avec les modifications du cortisol plasmatique mais très corrélées avec celles de PRA (P < 0,001). Il existe une corrélation très significative entre l'aldostéronémie et la kaliémie chez les sujets anéphriques étudiés en dehors de l'administration de Kayexalate (P < 0,001). Chez les sujets anéphriques recevant du Kayexalate l'aldostéronémie et la kaliémie sont stables et aucune corrélation n'est obtenue. Aucune variation nycthémérale de l'aldostéronémie n'a été observé dans les groupes de sujets anéphriques alors que la concentration de cortisol plasmatique varie comme chez les sujets normaux. Il peut être conclu de ces études que les variations nycthémérales de l'aldostéronémie dépendent de la stimulation par le système rénine-angiotensine. La perte de cette stimulation n'a pas d'effet sur la cortisolémie

Outcomes following aortic valve procedures in 201 complex congenital heart disease cases:results from the UK National Audit

OBJECTIVES: Some patients with complex congenital heart disease (cCHD) also require aortic valve (AoV) procedures. These cases are considered high risk but their outcome has not been well characterized. We aim to describe these scenarios in the current practice, and provide outcome data for counselling and decision-making. METHODS: This was a retrospective study using the UK National Congenital Heart Disease Audit data on cCHD patients undergoing aortic valve replacement, balloon dilation (balloon aortic valvuloplasty) or surgical repair (surgical aortic valve repair) between 2000 and 2012. Coarsened exact matching was used to pair cCHD with patients undergoing AoV procedures for isolated valve disease. RESULTS: A total of 201 patients with a varied spectrum of cCHD undergoing 242 procedures were included, median age 9.4 years (1 day–65 years). Procedure types were: balloon aortic valvuloplasty (n = 31, 13%), surgical aortic valve repair (n = 57, 24%) and aortic valve replacement (n = 154, 63%). Mortality at 30 days was higher in neonates (21.8% vs 5.3%, P = 0.02). Survival at 10 years was 83.1%, freedom from aortic valve replacement 83.8% and freedom from balloon aortic valvuloplasty/surgical aortic valve repair 86.3%. Neonatal age (P < 0.001), single ventricle (P = 0.08), concomitant Fontan/Glenn (P = 0.002) or aortic arch procedures (0.02) were associated with higher mortality. cCHD patients had lower survival at 30 days (93% vs 100%, P = 0.003) and at 10 years (86.4% vs 96.1%, P = 0.005) compared to matched isolated AoV disease patients. CONCLUSIONS: AoV procedures in cCHD can be performed with good results outside infancy, but with higher mortality than in isolated AoV disease. Neonates and patients with single ventricle defects, especially those undergoing concomitant Fontan/Glenn, have worse outcomes

Improved multidetector asymmetrical-flow field-flow fractionation method for particle sizing and concentration measurements of lipid-based nanocarriers for RNA delivery

Lipid-based nanoparticles for RNA delivery (LNP-RNA) are revolutionizing the nanomedicine field, with one approved gene therapy formulation and two approved vaccines against COVID-19, as well as multiple ongoing clinical trials. As for other innovative nanopharmaceuticals (NPhs), the advancement of robust methods to assess their quality and safety profiles—in line with regulatory needs—is critical for facilitating their development and clinical translation. Asymmetric-flow field-flow fractionation coupled to multiple online optical detectors (MD-AF4) is considered a very versatile and robust approach for the physical characterisation of nanocarriers, and has been used successfully for measuring particle size, polydispersity and physical stability of lipid-based systems, including liposomes and solid lipid nanoparticles. However, the unique core structure of LNP-RNA, composed of ionizable lipids electrostatically complexed with RNA, and the relatively labile lipid-monolayer coating, is more prone to destabilization during focusing in MD-AF4 than previously characterised nanoparticles, resulting in particle aggregation and sample loss. Hence characterisation of LNP-RNA by MD-AF4 needs significant adaptation of the methods developed for liposomes. To improve the performance of MD-AF4 applied to LNP-RNA in a systematic and comprehensive manner, we have explored the use of the frit-inlet channel where, differently from the standard AF4 channel, the particles are relaxed hydrodynamically as they are injected. The absence of a focusing step minimizes contact between the particle and the membrane, reducing artefacts (e.g. sample loss, particle aggregation). Separation in a frit-inlet channel enables satisfactory reproducibility and acceptable sample recovery in the commercially available MD-AF4 instruments. In addition to slice-by-slice measurements of particle size, MD-AF4 also allows to determine particle concentration and the particle size distribution, demonstrating enhanced versatility beyond standard sizing measurements.publishedVersio