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Contrast sensitivity deficits in patients with mutation-proven inherited retinal degenerations
摘要： Background: Patients with retinal diseases frequently complain of poor visual function even when visual acuity is relatively unaffected. This clinical finding has been attributed to deficits in contrast sensitivity (CS). The purpose of our study was to evaluate the CS in patients with clinical and genetic diagnosis of inherited retinal degeneration (IRD) and relatively preserved visual acuity. Methods: Seventeen patients (30 eyes) with IRD and visual acuity of 20/40 or better, and 18 controls (18 eyes) without any ocular condition underwent slit lamp examination, visual acuity testing via standard Snellen chart testing, CS testing via the Quick Contrast Sensitivity Function (QCSF), and Spectral Domain Optical Coherence Tomography (SD-OCT). CS were measured at 1.0, 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd). T tests with general estimated equations were used to compare CS between groups. Wald chi square followed by pairwise comparisons was used to compare CS between multiple groups. Results: We included 12 patients with rod-cone dystrophy (RCD), 3 patients with Stargardt disease (STGD) and 2 patients with Best disease. Patients with IRD had significantly worse CS than controls (p < 0.001) in all spatial frequencies. Patients with STGD had more marked deficits in CS than patients with Best disease (p < 0.001) and RCD (p < 0.001) despite having similar visual acuities. Conclusion: Patients with IRD, especially patients with STGD with relatively preserved visual acuity have marked deficits in CS when measured across a range of spatial frequencies. We recommend that clinical trials for STGD incorporate CS measured over a range of spatial frequencies as a secondary clinical endpoint for monitoring visual function. CS may provide an explanation for complaints of visual dysfunction when visual acuity is not significantly altered.
关键词： Best disease,Contrast sensitivity,Retinal dystrophy,Retinitis Pigmentosa,Stargardt disease
更新于2025-09-23 15:23:52
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Lightweight Design of Multi-Objective Topology for a Large-Aperture Space Mirror
摘要： For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.
关键词： lightweight structure,space mirror,multi-objective topology optimization,sensitivity analysis
更新于2025-09-23 15:23:52
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Simulation-Based Sensitivity Analysis of Conduction and Switching Losses for Silicon Carbide Power MOSFETs
摘要： The behavior of silicon carbide power MOSFETs is analyzed using TCAD device simulations with respect to conduction and switching losses. Device designs with varying breakdown voltages are simulated. The contributions to the on-state resistance are shown at room and elevated temperature. Whereas channel and substrate resistance dominate at low breakdown voltages, drift and JFET resistance dominate at high breakdown voltages. With increasing temperature, the channel resistance decreases and thus the drift resistance is the main contributor already at medium breakdown voltages. Manufacturing processes of a device can have a high influence on its losses. Variations in interface mobility, drift doping, and p-body doping can lead to a significant change of on-resistance, internal capacitances, and reverse recovery charge. For higher voltage classes the drift layer properties should be of major interest as it influences on-resistance and reverse recovery charge.
关键词： SiC power MOSFET,TCAD device simulation,sensitivity analysis,losses
更新于2025-09-23 15:23:52
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Assessment of red-edge vegetation indices for crop leaf area index estimation
摘要： This study explores the potential of vegetation indices (VIs) for crop leaf area index (LAI) estimation, with a focus on comparing red-edge reflectance based (RE-based) and the visible reflectance based (VIS-based) VIs. Seven VIs were derived from multi-temporal RapidEye images to correlate with LAI of two crop species having contrasting leaf structures and canopy architectures: spring wheat (a monocot) and canola (a dicot) in northern Ontario, Canada. The relationship between LAI and the selected VIs (LAI-VI) was characterized using a semi-empirical model. The Markov Chain Monte Carlo (MCMC) sampling method was used to estimate the model parameters, including the extinction coefficient (KVI) and VI value for dense green canopy (VI∞). Results showed that crop-specific regression models were much closer to a generic regression model using the RE-based VIs than using the VIS-based VIs. Furthermore, the joint posterior probability distribution of the KVI and VI∞ of the RE-based VIs tended to converge for the two crops. This suggests that the RE-based VIs are not as sensitive to canopy structure, e.g., the average leaf angle (ALA), as the VIS-based VIs. This is also demonstrated by the sensitivity analyses using both PROSAIL simulations and field measurements. Hence, the RE-based VIs can be used to develop a more generic LAI estimation algorithm for different crops. Further studies are required to assess the impact of soil reflectance and other factors, such as illumination-target-viewing geometries and atmospheric conditions, on LAI retrieval.
关键词： Sensitivity analysis,Crops,RapidEye,Leaf area index,red-edge,Vegetation index
更新于2025-09-23 15:23:52
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Narrowband and Full-Angle Refractive Index Sensor Based on a Planar Multilayer Structure
摘要： This work reports a design of a narrowband and full-angle refractive index sensor based on Tamm plasmon resonance (TPR) by introducing a distributed Bragg reflector (DBR) integrated with a non-adjacent metal layer. The analyte flows into the cavity comprising of the DBR and the non-adjacent metal layer. Simulated results show that the incident light can be strongly confined in the specially designed cavity. The sharp reflection dip within the forbidden band of the isolated DBR indicates the excitation of Tamm mode, and the spectral characteristics were monitored upon exposure to various analytes with different refractive indices. The optimally designed system shows the sensitivity (S) and full width at half-maximum (FWHM) can be up to 860 nm/RIU (refractive index unit) and ~2.2 nm with a figure of merit (FOM) of 391. Furthermore, the highly-sensitive characteristic can be sustained in a wide angle range of 0° to almost 90° under both TM- and TE-polarized lights.
关键词： sensitivity,refractive index sensor,Tamm plasmon resonance,figure of merit
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Life Sciences Conference (LSC) - Montreal, QC, Canada (2018.10.28-2018.10.30)] 2018 IEEE Life Sciences Conference (LSC) - Assay Development and Storage for Fluorescence-Based Lateral Flow Immunoassay
摘要： Point-of-care medical diagnostics can provide efficient, cost-effective medical care, and have the potential to fundamentally change our current approach to global health. There have been substantial efforts in developing lateral flow assays for serologic testing, but most of the existing approaches have limited portability, are expensive, and offer limited analytical sensitivity. In this paper, we demonstrated an assay for the detection of antibodies in plasma to Epstein-Barr Nuclear Antigen-1 (EBNA-1) protein and optimization of the assay including washing and blocking conditions. We also investigated the effect of the storage on the assay strips. Using our optimized conditions, we were able to detect anti-Human Papilloma Virus (HPV)-16 E7 antibodies after three weeks of storage. Our goal is to adapt this system to detect HPV biomarkers for cervical cancers in low and middle-income countries.
关键词： storage,immunoassay,sensitivity,Lateral flow assay,fluorescence,point-of-care
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Sciences and Humanities International Research Conference (SHIRCON) - Lima, Peru (2018.11.20-2018.11.22)] 2018 IEEE Sciences and Humanities International Research Conference (SHIRCON) - A Visible Fluorescence Method Induced by UV Radiation for Detection of Infestation in Canary Beans
摘要： The proposed study aims to present an algorithm for the detection of infestation of canary beans of the species "Phaseolus Vulgaris" by generating a visible fluorescence under UV radiation, which allows the bean to be distinguished as healthy or infested. Currently, since many of the symptoms of infestation cannot be detected by the human eye, the beans sample analysis is highly subjective. The proposed method uses images of the beans taken under UV radiation within a hermetic enclosure. Then the image is acquired and an image segmentation algorithm is executed in order to identify the beans. Each bean is labeled so that the infestation can be detected by an algorithm based on histogram analysis. For the validation of the proposed method, several samples were evaluated and the results were compared with those obtained by two experts through an exhaustive visual analysis. The results were expressed through specificity and sensitivity, obtaining 99.78% for specificity and 90.70% for sensitivity.
关键词： canary bean,UV radiation,image processing,infestation,visible fluorescence,specificity,sensitivity,detection
更新于2025-09-23 15:22:29
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Cross-Sectional and Longitudinal Assessment of Retinal Sensitivity in Patients With Childhood-Onset Stargardt Disease
摘要： Purpose: We assess cross-sectional and longitudinal microperimetry and full-field static perimetry-derived retinal sensitivity with conventional and volumetric indices of retinal function in childhood-onset Stargardt disease (STGD1). Methods: Subjects with molecularly confirmed childhood-onset STGD1 underwent full-field static perimetry and/or microperimetry using custom designed grids. Mean sensitivity (MS) and total volume (VTOT) were computed for each microperimetry test. MS, VTOT, and central field volume (V30) were computed for each full-field static perimetry test. Subjects under 18 years old at baseline were classified as children and subjects 18 years or older as adults. Results: A total of 43 children (mean age at baseline, 13.0 years; range, 8–17) and 13 adults (mean age at baseline, 23.1 years; range, 18–32) were included in the analysis. For full-field static perimetry and microperimetry for both subgroups, intraclass correlation coefficient results for MS and volumetric indices were good to excellent, indicating strong test–retest reliability. Interocular symmetry in terms of baseline measurements and the annual rate of progression was observed. A greater rate of progression was observed in childhood. Conclusions: To our knowledge, this is the first prospective study of retinal sensitivity in a large cohort of molecularly confirmed subjects with childhood-onset STGD1 demonstrating that children with STGD1 can reliably undertake detailed functional testing. Moreover, using custom designed grids and subsequent topographic analysis, volumetric indices of retinal function provide a reliable measure of retinal sensitivity.
关键词： endpoints,Stargardt disease,retina,clinical trials,ABCA4,perimetry,visual field,STGD1,Retinal sensitivity
更新于2025-09-23 15:22:29
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Temperature effect on structural, optical and NH<SUB align="right">3 gas sensing properties of TeO<SUB align="right">2 thin films
摘要： TeO2 thin films with different temperatures (400, 450 and 500°C) were deposited on glass substrates by thermal evaporation technique from a Te powder. XRD patterns indicate that as the temperature increases, the crystallisation improves. Observing the images obtained by SEM, it is seen that the grain size decreases as the temperature increases. The optical energy gap of the films was determined from transmittance and reflectance spectra. The optical energy gap decreased continuously from 3.95 eV to 3.80 eV with increasing temperature. Studying the effect of deposition temperature on NH3 gas measurement, it became obvious that as the deposition temperature increases, the sensitivity increases and the response and recovery times decrease.
关键词： scanning electron microscope,XRD,thin films,sensitivity,X-ray diffraction,energy gap,SEM,optical
更新于2025-09-23 15:22:29
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Sensitivity enhancement of surface plasmon resonance biosensor based on graphene and barium titanate layers
摘要： A surface plasmon resonance-based biosensor, consisting prism, silver, barium titanate (BaTiO3) and graphene layers, is presented by using angular interrogation. The structure is specially designed to further enhance the sensitivity and to decrease the full width at half maximum (FWHM) thereby improving the sensor performance. Theoretical analysis shows that the highest sensitivity can reach at 257°/RIU where the thickness of Ag layer is 45 nm with 10 nm BaTiO3 and one graphene layer. Compared with existing biosensors, the proposed biosensor exhibits higher sensitivity, lower FWHM and two times better preformation in the quality factor of the sensor, which would make our design have more applications in the field of biosensors.
关键词： Biosensor,Barium titanate,Graphene,Sensitivity,Surface plasmon resonance
更新于2025-09-23 15:22:29