The Relationship Between Retinal Vessel Oxygenation and Spatial Distribution of Retinal Nonperfusion in Retinal Vascular Diseases

Purpose: We study the relationship between retinal vessel oxygenation and the spatial distribution of retinal nonperfusion using ultrawide field angiography in eyes with retinal vascular diseases. Methods: This prospective single center study recruited 57 eligible eyes from 44 patients with retinal vascular diseases. Retinal oximetry measurements were obtained using the Oxymap T1 device to determine the arteriovenous (AV) difference. Retinal nonperfusion was measured from ultrawide field angiography images taken with the Optos 200TX system and superimposing the images with the concentric rings template to determine the area and distribution of retinal nonperfusion. Results: Seven (12.3%) eyes had a diagnosis of a branch or hemiretinal vein occlusion, 24 (42.1%) with central retinal vein occlusion and 26 (45.6%) with diabetic retinopathy (11 [19.3%] nonproliferative and 15 [26.3%] proliferative diabetic retinopathy). The correlation between the total area of retinal nonperfusion with the AV difference controlling for age was not statistically significant (R = -0.103, P = 0.449). However, when analyzing the correlation of AV difference with the area of retinal nonperfusion in the posterior pole controlling for age and peripheral nonperfusion, this was significant (R = -0.295, P = 0.029). This was not significant for the area of retinal nonperfusion in the periphery while controlling for posterior pole nonperfusion and age (R = 0.124, P = 0.368). Conclusions: Retinal nonperfusion has a negative correlation with AV difference measured on retinal oximetry. This correlation is significant in the posterior pole, but not in the peripheral retina

Translucency parameter of conventional restorative glass-ionomer cements.

OBJECTIVE: To evaluate the translucency parameter (TP) and contrast ratio (CR) of different conventional restorative glass-ionomer cements (GICs). MATERIALS AND METHODS: Eighteen brands of GICs were evaluated. Five disks of each material were made following ISO 9917-1. The luminous reflectance and Central Bureau of the International Commission on Illumination parameters of disks were evaluated using a colorimeter, against backings of white and black, to obtain the translucent parameter and contrast ratio of different brands of glass-ionomer cements. The correlation between translucency parameter and contrast ratio was assessed with the Pearson correlation test. The translucent and contrast ratio parameters values were submitted to the one-way ANOVA and Tukey test for multiple comparisons (p < 0.05). RESULTS: There was a strong inverse relationship between CR and TP (r2 = 0.94, p < 0.001). The contrast ratio decreased as translucency increased. There were significant differences in TP and CR among brands (p < 0.001). CONLUSIONS: GICs exhibit different translucency and contrast ratio behavior. Some brands of GICs presented very low TP and this condition would be unacceptable for areas with esthetic demands. In addition, TP and CR showed a strong linear relationship. CLINICAL SIGNIFICANCE: The results found in this study demonstrated that the knowledge of the translucency and CR of different conventional restorative GICs is important in order to guide clinicians in the selection of restorative GICs for anterior teeth

Optical fibre-based environmental sensors utilizing wireless smart grid platform

With the advent and development of smart grid in recent years, traditional power grid is undergoing a profound revolution. By utilizing modern wireless technology and sensor, wireless smart grid (WSG) can effectively solve many hard and haunting issues in traditional grid, such as high maintenance costs, poor scalability, low efficiency and stability. In a WSG, data are collected by sensors at first and then transmitted to base station through wireless network. After receiving those data, corresponding actions are executed by control center. We present the integration of optical fibre-based sensor to WSG platform for real-time environmental monitoring. As a proof-of-concept, an optical fibre sensor for refractive index (RI) sensing of fresh water is adopted. The sensing mechanism relies on the reflectance at the fibre interface, where the intensity of the reflected spectra is registered corresponding to the change of the RI of the ambient environment. A sensitivity of 29.3 dB/RIU is achieved for the fabricated fibre sensor within the RI range of 1.33–1.46, and the acquired data is transmitted through wireless smart meters

Influence of severe plastic deformation on the precipitation hardening of a FeSiTi steel

The combined strengthening effects of grain refinement and high precipitated volume fraction (~6at.%) on the mechanical properties of FeSiTi alloy subjected to SPD processing prior to aging treatment were investigated by atom probe tomography and scanning transmission electron microscopy. It was shown that the refinement of the microstructure affects the precipitation kinetics and the spatial distribution of the secondary hardening intermetallic phase, which was observed to nucleate heterogeneously on dislocations and sub-grain boundaries. It was revealed that alloys successively subjected to these two strengthening mechanisms exhibit a lower increase in mechanical strength than a simple estimation based on the summation of the two individual strengthening mechanisms

Quantifying Retinal Area in Ultra-Widefield Imaging Using a 3-Dimensional Printed Eye Model

Purpose: To study the effects of different axial lengths on ultra-widefield imaging to determine the presence of distortion in images despite software correction and calculate an enlargement factor based on angular location. / Design: Experimental image analysis study. / Study Objects: Three 3-dimensional printed model eyes simulating eyes with axial lengths of 22, 24, and 26 mm. Each model has a grid of rings 9° apart centered at the posterior pole. / Methods: Single-center study performed at the National Institute for Health Research Moorfields Biomedical Research Centre (London, UK). Each model was imaged using Optos 200TX (Optos, Dunfermline, UK). Two images for each model eye that were corrected using V2 Vantage Pro software (Optos) were used for analysis and the average values obtained. Each image inter-ring area was measured using ImageJ to obtain a measured image area in pixel and square millimeters. This was compared with the true calculated object inter-ring area and an enlargement factor was determined. / Main Outcome Measures: Measured image inter-ring area in pixels and square millimeters. True calculated object inter-ring area in square millimeters. / Results: The enlargement factor of the rings gradually increases toward the periphery with factors of 1.4 at 45° and 1.9 at the equator. The axial lengths did not affect the enlargement factor of the rings imaged in 3 different model eyes (P = 0.9512). The anterior equator exhibits a significant distortion despite the software correction. / Conclusion: The enlargement factor depends on angular location and not axial length. The enlargement factors can be used in clinical practice to more accurately measure area in ultra-widefield imaging

Retinal non-perfusion in the posterior pole is associated with increased risk of neovascularization in central retinal vein occlusion.

PURPOSE: To review the definition of ischaemic central retinal vein occlusion (CRVO) and stratify the risk of neovascular complication based on wider areas of visible retinal non-perfusion. DESIGN: Retrospective consecutive case series and image analysis study METHODS: Setting: Moorfields Eye Hospital, London, United Kingdom. STUDY POPULATION: 42 consecutive treatment naïve eyes with CRVO imaged with ultra-widefield angiography with a minimum of 12 months follow-up. OBSERVATION PROCEDURE: The spatial location and total area of retinal non-perfusion (measured in disc areas, DA) were determined using the validated concentric rings method. The area was corrected for projection distortion. The images were graded by two retinal physicians and average measurements used. MAIN OUTCOME MEASURES: Development of neovascular complications. RESULTS: The percentage of eyes developing new vessels increased from none in eyes with less than 10 DA of non-perfusion in total, to 14.3% in eyes with 10-30DA, 20.0% for 30-75DA and 80% risk with 75-150DA of non-perfusion. From 13 (31.0%) eyes with a perfused posterior pole (an area encompassing a five disc diameter radius centered at the fovea) and more than 10DA of non-perfusion isolated in the periphery (beyond the posterior pole), only one (7.7%) eye developed new vessels, OR 0.12 [95% CI:0.01,1.03]. Comparatively, for 13 (31.0%) eyes with more than 10DA of non-perfusion in the posterior pole, 11 (84.6%) developed new vessels, OR 74.25 [95% CI: 9.26, 595.30], p<0.001. CONCLUSION: With ultra-widefield angiography, we have ascertained that posterior pole non-perfusion of more than 10DA remains the key risk factor for new vessel development compared to areas of non-perfusion confined to the periphery

Explaining the human resource management preferences of employees: A study of Chinese workers

The forces of globalization, technology and the differences or similarities in institutional systems place substantial pressure on convergence and divergence in HRM practices. Moreover, local customs and the responses from employees also pose serious constraints on the degree of convergence or divergence (Rowley and Benson 2002). In other words, there is what might be termed an upward influence coming from the employees. Although companies may benchmark HRM ‘best practices’, the actual adoption and success of these practices depends, to a large extent, on perceptions and acceptance from employees. However, the opinions of non-managerial employees have been largely neglected in the studies of HRM (Cooke 2009; Legge 1995; Guest 2002; Edgar and Geare 2005; Qiao, Khilji and Wang 2009). Cooke (2009), after reviewing studies on HRM in China published between 1998 and 2007 in major business and management journals, reported that two-thirds of the studies had collected data from managers and most of them relied on managers as the sole source for information. Since the information has mainly been provided by managers, there is the potential for bias because feedback from the managers probably reflects the ideal or ‘best practices’ of HRM that those managers want to implement, rather than the actual HR policies or practices being used in the organization. Thus Cooke (2009, p.19) argued that ‘unless we can broaden our research catchment to include views from the widest range of stakeholders, particularly the employees, our understanding of HRM in China remains partial, from management’s lens’. This study explores the HR preferences of Chinese employees, both non-managerial and managerial ones, based on a sample of 2852 questionnaires from companies in China. A number of questions are explored. For example, what do they think of a ‘promotion-from-within’ policy? Do they prefer an individual-based bonus or a group-based bonus? Do they prefer a ‘downward performance appraisal method’ or a ‘multi-source performance appraisal method’? The research findings shows a strong ‘group orientation’ and a great emphasis on ‘soft factors’ such as seniority, loyalty and connections in many HRM areas. The debate on whether Chinese HRM will converge or diverge towards the Western models is still ongoing. Many argue that there could be further convergence towards the Western practices because globalization may place substantial pressure on firms to standardize practices and policies (see Chen, Lawler and Bae 2005). Others argue that HRM is highly context specific in which institutional and cultural forces have enduring influences (see Rowley and Cooke 2010), which indicates a divergent perspective. The third group supports a ‘cross-vergence’ view which argues that there will be signs of convergence in certain areas but Chinese HRM will keep its ‘Chinese characteristics’ (Cooke 2005, 2010; Yeung, Warner and Rowley 2008; Warner 2009a, b). This study supports the ‘cross-vergence’ perspective. It is argued that certain areas of Chinese HRM are converging to the Western model, but the influence of traditional Chinese personnel practices remains strong. A ‘group orientation’, a major emphasis on ‘soft factors’ and a trade union presence is likely to remain as the three main features of Chinese HRM in the long-term