Effects of Space Charge, Dopants, and Strain Fields on Surfaces and Grain Boundaries in YBCO Compounds

Statistical thermodynamical and kinetically-limited models are applied to study the origin and evolution of space charges and band-bending effects at low angle [001] tilt grain boundaries in YBa$_2$Cu$_3$O$_7$ and the effects of Ca doping upon them. Atomistic simulations, using shell models of interatomic forces, are used to calculate the energetics of various relevant point defects. The intrinsic space charge profiles at ideal surfaces are calculated for two limits of oxygen contents, i.e. YBa$_2$Cu$_3$O$_6$ and YBa$_2$Cu$_3$O$_7$. At one limit, O$_6$, the system is an insulator, while at O$_7$, a metal. This is analogous to the intrinsic and doping cases of semiconductors. The site selections for doping calcium and creating holes are also investigated by calculating the heat of solution. In a continuum treatment, the volume of formation of doping calcium at Y-sites is computed. It is then applied to study the segregation of calcium ions to grain boundaries in the Y-123 compound. The influences of the segregation of calcium ions on space charge profiles are finally studied to provide one guide for understanding the improvement of transport properties by doping calcium at grain boundaries in Y-123 compound.Comment: 13 pages, 5 figure

Development and validation of a new photographic scale to grade lid wiper epitheliopathy

Purpose: Lid wiper epitheliopathy (LWE) is a clinical sign that has been associated with dry eye disease (DED) and contact lens discomfort (CLD). This study describes the development, validation and graders’ preference of a new photographic scale for LWE, the Photographic Lid Wiper Epitheliopathy (PLWE) scale. Methods: The PLWE grading scale was developed using LWE images selected from 57 screened patients (≥18 years of age) with confirmed LWE in both eyes. To validate the PLWE scale, a set including 20 images showing varying degrees of LWE from none to severe was chosen. To assess grading validity and grading reliability, observers were asked to grade the selected images using the PLWE and another commonly used subjective LWE grading protocol (Korb) on two separate sessions. Results: The mean grade (±SD) of all images was not statistically significant different between the PLWE scale (1.55 ± 0.44) and the alternative grading scale (Korb, 1.47 ± 0.54) (ANOVA F1, p > 0.05). The average dif- ference from the mean of all graders was 0.03 ± 0.53 using the PLWE scale and 0.06 ± 0.57 when using the Korb protocol (ANOVA F1, p > 0.05). The Coefficient of Repeatability was 1.04 and 1.12 for the PLWE and Korb scales (p > 0.05). Ninety-five percent of the graders found PLWE easier to use than Korb and the same percentage would consider using the PLWE scale in clinical practice. Conclusion: The format of the PLWE is similar to other anterior segment visual grading scales and this study revealed an ease of use preference for employing the PLWE by the graders. The presence of LWE has been associated with DED and CLD, and the addition of this new photographic scale could facilitate clinical judgement and record keeping of LWE in clinical practice

The effect of the COVID‐19 pandemic on working practices of UK primary care optometrists

Purpose: In late 2019, a new coronavirus capable of infecting humans, SARS‐CoV‐2, was identified in Wuhan, China. The resultant respiratory disease was subsequently named COVID‐19. In March 2020, in response to the COVID‐19 pandemic, primary care optometry practices only remained open to deliver essential or emergency eye care. This study aimed to characterise the experiences of United Kingdom (UK)‐based primary care optometrists during the COVID‐19 pandemic. Methods: An email invitation to participate in an online cross‐sectional survey was sent to 3000 UK‐based, currently practicing members of The College of Optometrists (UK). Responses to the structured questionnaire were analysed using descriptive statistics, including frequencies, means and standard deviations. Frequency analyses were used to evaluate items with multiple responses. Free‐text responses were examined using thematic analyses. Results: After data cleaning, a total of 1250 responses remained. Sixty‐three percent were female, 70% self‐identified as being of white ethnicity and 78% were based in England. During the first national lockdown, over half of all respondents were involved with the provision of remote consultations for emergency/urgent care. The majority felt ‘very’/‘moderately’ comfortable conducting remote consultations, but 66% felt professional liability was increased. Forty percent were involved in the provision of face‐to‐face consultations. Eye‐health and vision‐related problems were the most commonly reported patient issues during both remote and face‐to‐face consultations, while contact‐lens related problems were the least. Thematic analysis of the responses showed several challenges adjusting to the pandemic (e.g., working safely), but also some potential benefits (e.g., increased skills). Conclusions: The findings provide an overview of changes to optometric practice in the UK during the COVID‐19 pandemic. The results may be used to inform the development of professional guidance and facilitate resource allocation for safe and effective eye care during this and any future pandemics

Optometry practice in the UK in 2020 during the COVID-19 pandemic: initial response and ongoing clinical implications

To minimise the spread of COVID-19 during the pandemic, optometric practices had to restructure their service provision in order to provide a safe eyecare environment for their patients. These changes included the introduction of new pathways, enhanced infection control procedures, changes to assessment routines and greater use of remote consultations. Nagra et al. recently published a paper detailing the results of a survey conducted on practising members of the College of Optometrists investigating changes in clinical optometric practice in the UK as a result of the pandemic. This article summarises the key findings of the survey including the challenges and benefits identified, such as how to ensure safe working practices, how to continue to provide a comprehensive service and navigation of the financial implications. Benefits such as refined pathways, streamlined services, increased skill acquisition and improved professional relationships are also highlighted. The impact on current practice and implications for future clinical care are also discussed

A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding

Contains fulltext : 102577.pdf (publisher's version ) (Open Access)Background - This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI ) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding. Methods - Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions. Results - Children with normal vision show an extent of contour interaction over an area 1.5-3x as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1-2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2x larger than those seen adults with NV. The magnitude of the crowding effect is also 2x as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3x the size of that experienced by adults with NV. Conclusions - The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios and it shows that charts with 50% interoptotype spacing were most sensitive to capture crowding effects. The groups that showed the largest crowding effects were individuals with CN, VI adults with central scotomas and children with CVI. Perceptual Learning seems to be a promising technique to reduce excessive foveal crowding effects.14 p

Mutations with pathogenic potential in proteins located in or at the composite junctions of the intercalated disk connecting mammalian cardiomyocytes: a reference thesaurus for arrhythmogenic cardiomyopathies and for Naxos and Carvajal diseases

In the past decade, an avalanche of findings and reports has correlated arrhythmogenic ventricular cardiomyopathies (ARVC) and Naxos and Carvajal diseases with certain mutations in protein constituents of the special junctions connecting the polar regions (intercalated disks) of mature mammalian cardiomyocytes. These molecules, apparently together with some specific cytoskeletal proteins, are components of (or interact with) composite junctions. Composite junctions contain the amalgamated fusion products of the molecules that, in other cell types and tissues, occur in distinct separate junctions, i.e. desmosomes and adherens junctions. As the pertinent literature is still in an expanding phase and is obviously becoming important for various groups of researchers in basic cell and molecular biology, developmental biology, histology, physiology, cardiology, pathology and genetics, the relevant references so far recognized have been collected and are presented here in the following order: desmocollin-2 (Dsc2, DSC2), desmoglein-2 (Dsg2, DSG2), desmoplakin (DP, DSP), plakoglobin (PG, JUP), plakophilin-2 (Pkp2, PKP2) and some non-desmosomal proteins such as transmembrane protein 43 (TMEM43), ryanodine receptor 2 (RYR2), desmin, lamins A and C, striatin, titin and transforming growth factor-β3 (TGFβ3), followed by a collection of animal models and of reviews, commentaries, collections and comparative studies

Arrhythmogenic right ventricular cardiomyopathy/dysplasia

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a heart muscle disease clinically characterized by life-threatening ventricular arrhythmias. Its prevalence has been estimated to vary from 1:2,500 to 1:5,000. ARVC/D is a major cause of sudden death in the young and athletes. The pathology consists of a genetically determined dystrophy of the right ventricular myocardium with fibro-fatty replacement to such an extent that it leads to right ventricular aneurysms. The clinical picture may include: a subclinical phase without symptoms and with ventricular fibrillation being the first presentation; an electrical disorder with palpitations and syncope, due to tachyarrhythmias of right ventricular origin; right ventricular or biventricular pump failure, so severe as to require transplantation. The causative genes encode proteins of mechanical cell junctions (plakoglobin, plakophilin, desmoglein, desmocollin, desmoplakin) and account for intercalated disk remodeling. Familiar occurrence with an autosomal dominant pattern of inheritance and variable penetrance has been proven. Recessive variants associated with palmoplantar keratoderma and woolly hair have been also reported. Clinical diagnosis may be achieved by demonstrating functional and structural alterations of the right ventricle, depolarization and repolarization abnormalities, arrhythmias with the left bundle branch block morphology and fibro-fatty replacement through endomyocardial biopsy. Two dimensional echo, angiography and magnetic resonance are the imaging tools for visualizing structural-functional abnormalities. Electroanatomic mapping is able to detect areas of low voltage corresponding to myocardial atrophy with fibro-fatty replacement. The main differential diagnoses are idiopathic right ventricular outflow tract tachycardia, myocarditis, dialted cardiomyopathy and sarcoidosis. Only palliative therapy is available and consists of antiarrhythmic drugs, catheter ablation and implantable cardioverter defibrillator. Young age, family history of juvenile sudden death, QRS dispersion ≥ 40 ms, T-wave inversion, left ventricular involvement, ventricular tachycardia, syncope and previous cardiac arrest are the major risk factors for adverse prognosis. Preparticipation screening for sport eligibility has been proven to be effective in detecting asymptomatic patients and sport disqualification has been life-saving, substantially declining sudden death in young athletes