Inherent properties of binary tetrahedral semiconductors

A new approach utilising the concept of ionic charge theory has been used to explain the inherent properties such as lattice thermal conductivity and bulk modulus of 3,5 and 2,6 semiconductors. The lattice thermal conductivity of these semiconductors exhibit a linear relationship when plotted on a log scale against the nearest neighbour distance but fall on two straight lines according to the product of the ionic charge of the compounds. On the basis of this result a simple relationship of lattice thermal conductivity with bulk modulus is proposed and used to estimate the bulk modulus of these semiconductors. A fairly good agreement has been found between the experimantal and calculated values of these parameters for zinc blende structured solids.Comment: 6 pages, 19 reference

Development and validation of a new glaucoma screening test using temporally modulated flicker

Purpose Describing the psychometric characteristics and diagnostic accuracy of the Accelerator 4‐Alternative Forced‐Choice Flicker Test prototype (A4FTp) for detecting chronic open angle glaucoma (COAG). Methods A4FTp measures temporally‐modulated flicker thresholds in regions of the visual field with high susceptibility to glaucomatous loss. We initially evaluated its psychometric properties on 20 normals (aged 33.8 ± 8.5 years) who were tested multiple times over a period of 3 months. All subjects underwent four repetitions for shorter (T8) and longer (T12) staircase termination criteria, to determine the most suitable threshold criterion. Four randomly selected subjects underwent a total of 10 repetitions to study test‐retest repeatability and learning effects. To determine its diagnostic accuracy, one eye of 40 participants with COAG and 38 normal controls were tested with the A4FTp in comparison with the Frequency Doubling Technology (FDT; C20‐5 programme) and iVue Spectral Domain Optical Coherence Tomography (SD‐OCT). Tests were conducted in a random order with results masked to the clinician conducting the reference ophthalmic examination. The accuracy of each test was determined by analysis of the area under the receiver operator characteristic curve (AUROC). Results A4FTp flicker thresholds were stable, with standard deviations of only 0.52 decilog (dL) for T8, increasing to 1.32 dL for T12, and no significant flicker sensitivity threshold improvement over the 10 repeat runs. T8 was superior to T12 on several other measures, so it was used for the remaining comparisons. In terms of diagnostic accuracy, the mean AUROC for the three tests were A4FTp [T8 criterion; 0.82, 95% confidence interval (0.73–0.92)]; SD‐OCT [any RNFL parameter p < 1% level; 0.90 (0.83–0.97)]; and FDT [one or more locations missed at p < 5% level; 0.91 (0.82–0.96)]. There was no statistical difference in AUROC between A4FTp and SD‐OCT (p = 0.18) or FDT (p = 0.12). The A4FTp test duration averaged just over 2 min per eye, taking approximately one‐third of the time for completion of the HFA SITA 24‐2 algorithm (conducted as part of the reference examination) and twice the time for the suprathreshold FDT. Conclusion Test accuracy for the A4FTp was comparable to those of the FDT and SD‐OCT for the detection of COAG. Time taken to complete the A4FTp was relatively short and initial results are promising. With further refinement, the A4FTp could have a future role in glaucoma detection

Effect of Yaw Torque on Load Sharing and Dynamics of Co-Axial Rotors

The previous load sharing method for a coaxial rotor system with an infinite number of blades is expanded for a system with a finite number of blades. In the previous methods, the load sharing case was developed only for the case where the load was evenly shared between the two rotors. However, an even distribution is not always needed and therefore a load distribution factor, f, was added to the system to accommodate for uneven load distributions. The addition of f allowed for the development of a correlation to adjust the input f to adjust the load sharing in the finite blade simulations to reach the desired load distribution. This independent study develops an understanding of how changing from a system with an infi-nite number of blades to a system with a finite number of blades impacts the load sharing relationship. This is accomplished through the following: 1) update the load sharing relationship for a finite-state inflow model with an infinite number of blades to allow for a load distribution factor, f, between both rotors, 2) apply the system for load sharing from the infinite number of blades system to the finite number of blades system, 3) find the f_effective to correct the load sharing distribution for a finite number of blades, and 4) analyze the trends with relation to f and rotor spacing d

A review of challenges from increasing renewable generation in the Indian Power Sector: Way forward for Electricity (Amendment) Bill 2020

About 70% of India’s current energy mix comprises of coal, and the increase in generation from renewable (RE) sources is affecting the health of the power system. We investigated this effect through the lens of asset utilisation, cost and the social disruption caused by accelerating RE into the Indian Power System. Our review-driven analysis revealed that increasing RE generation is pushing the coal plants to operate in low-loading conditions, causing heightened wear and tear of the plant as they are not suitable for flexible operation. The novel analysis of social disruption due to market parity between RE and coal-based generation presented a holistic view of the political economy of Indian Power System. We found that transition from coal to RE may have extended socio-political ramifications that can potentially disrupt the national economy at an unprecedented scale. Policy implications outlined by our study for the draft Electricity (Amendment) Bill 2020 include scoping a socio-technical framework which supports just energy transition through better financial support mechanisms for flexible operation of coal plants. Focusing on clean-up over shut-down of coal plants and facilitating investments in battery storage technologies and cross-border electricity trade as RE and conventional fuel reach market parity. Bill and Melinda Gates Foundation [OPP1144] and Energy Transition Small Grant by Isaac Newton Trus

Role of advanced technology in the detection of sight-threatening eye disease in a UK community setting.

Background/aims: To determine the performance of combinations of structural and functional screening tests in detecting sight-threatening eye disease in a cohort of elderly subjects recruited from primary care. Methods: 505 subjects aged ≥60 years underwent frequency doubling technology (FDT) perimetry, iVue optical coherence tomography (iWellness and peripapillary retinal nerve fibre layer (RNFL) scans) and intraocular pressure with the Ocular Response Analyzer, all performed by an ophthalmic technician. The reference standard was a full ophthalmic examination by an experienced clinician who was masked to the index test results. Subjects were classified as presence or absence of sight-threatening eye disease (clinically significant cataract, primary open-angle glaucoma, intermediate or advanced age-related macular degeneration and significant diabetic retinopathy). Univariate and multivariate logistic regression analyses were used to determine the association between abnormal screening test results and the presence of sight-threatening eye disease. Results: 171 subjects (33.8%) had one or more sight-threatening eye diseases. The multivariate analysis found significant associations with any of the target conditions for visual acuity of <6/12, an abnormal FDT and peripapillary RNFL thickness outside the 99% normal limit. The sensitivity of this optimised screening panel was 61.3% (95% CI 53.5 to 68.7), with a specificity of 78.8% (95% CI 74.0 to 83.1), a positive predictive value of 59.5% (95% CI 53.7 to 65.2) and an overall diagnostic accuracy of 72.9% (95% CI 68.8 to 76.8). Conclusions: A subset of screening tests may provide an accurate and efficient means of population screening for significant eye disease in the elderly. This study provides useful preliminary data to inform the development of further larger, multicentre screening studies to validate this screening panel