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Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral-Domain Optical Coherence Tomography
摘要： PURPOSE. To report the retinal nerve ?ber layer (RNFL) defect volume deviation according to structural RNFL loss in RNFL thickness maps. METHODS. Retinal nerve ?ber layer defect is de?ned in RNFL thickness maps by the degree of RNFL loss. A 20% to 70% degree of RNFL loss was set with a 1% interval as the reference level for determining the boundary of RNFL defects. Each individual RNFL thickness map was compared with a normative database map and the region below the reference level was identi?ed as an RNFL defect. The RNFL defect volume was calculated by summing the volumes of each pixel inside RNFL defect. The RNFL defect volume deviation was calculated by summing the differences between the normative database and the subject’s RNFL measurements. To evaluate the glaucoma diagnostic ability, the areas under the receiver operating characteristics curves (AUCs) were calculated. RESULTS. Retinal nerve ?ber layer defect volume and RNFL defect volume deviation (0.984 and 0.986, respectively) had signi?cantly greater AUCs than all circumpapillary RNFL thickness parameters (all P < 0.001). In the early stage of RNFL loss (under 31% loss of RNFL), RNFL defect volume deviation showed better diagnostic performance than the RNFL defect volume. In multivariate analysis, RNFL defect volume and RNFL defect volume deviation were signi?cantly associated with the mean deviation in visual ?eld tests. CONCLUSIONS. Retinal nerve ?ber layer defect volume deviation is a useful tool for diagnosing glaucoma and monitoring RNFL change. In early stage of RNFL loss, RNFL defect volume deviation is more sensitive for detecting glaucoma than the RNFL defect volume measurements.
关键词： retinal nerve ?ber defect,spectral-domain optical coherence tomography,lost and remaining volume,glaucoma
更新于2025-09-09 09:28:46
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Introduction to Special issue on Geologic Remote Sensing
摘要： Herein we provide an overview of science and technology involved in remote sensing, and outlines some practical constraints in applications to geological problems. We further summarize diagnostic spectral features of important geological material that can be detected using satellite- and air-borne remote sensing. Finally, the papers contained in the special issue are briefly introduced.
关键词： Geologic Remote Sensing,Spectral Features,Hyperspectral Remote Sensing,LANDSAT,ASTER
更新于2025-09-09 09:28:46
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Optical Filter Designs for Multi-Color Visible Light Communication
摘要： In visible light communication (VLC), using multiple colors is an efficient way to enhance data rate, leading to multi-color VLC (MC-VLC). However, the performance of MC-VLC is jeopardized by the spectral overlaps of different colors. Thin-film optical filters, as the key component of MC-VLC systems, are usually adopted to separate colors. The passband bandwidth (BW) and center wavelength (CWL) of optical filters are critical to mitigate the crosstalk among colors, and thus must be carefully designed. Moreover, due to the intrinsic wavelength shift of the CWL with the varying of the angle of incidence (AoI), it is challenging to support mobility for MC-VLC. In this paper, we consider a joint design of multiple optical filters for MC-VLC by properly selecting the BW and CWL of each filter. We first investigate the optical filter design for a fixed receiver location. Then, to support mobility, we propose two robust optical filter designs, namely statistically and worst-case robust designs, which do not rely on the exact receiver location. Efficient methods are developed to solve the corresponding design problems and obtain the optimized optical filters. Compared with the existing optical filters, the proposed optical filters exhibits much better performance in various scenarios.
关键词： robust design,optical filter,spectrum shift,Mobility,multi-color LED,visible light communication,spectral overlap
更新于2025-09-09 09:28:46
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Phenotype Characteristics of Fellow Eyes in Patients With Early Onset of Neovascular Age-Related Macular Degeneration
摘要： PURPOSE. To investigate phenotype characteristics of fellow eyes in patients with early onset of neovascular age-related macular degeneration (NVAMD). METHODS. Patients with new-onset unilateral NVAMD between 50 and 65 years (n ? 57, early-onset choroidal neovascularization [CNV] group) or >80 years (n ? 47, late-onset CNV group) or with nonneovascular AMD (n ? 98, no-CNV group) were included. Fellow eyes in both CNV groups and the eyes with the more severe AMD staging in the no-CNV group were used to evaluate number and size of macular drusen, extramacular drusen (EMD), pigmentary abnormalities, and retinal pigment epithelium (RPE) atrophy on color photographs and hyperre?ective dots (HRD) and reticular pseudodrusen (RPD) on spectral-domain optical coherence tomography (SDOCT) scans. Regression analysis was used to compare groups. RESULTS. Occurrence of >20 macular drusen was more frequent in the early-onset CNV group than the late-onset CNV group (odds ratio [OR] 2.93; P ? 0.01) or the no-CNV group (OR 2.17; P ? 0.02). Retinal pigment epithelium atrophy, RPD, and HRD appeared less frequently in the early-onset CNV group than in the late-onset CNV group (RPE atrophy: OR 0.11; P ? 0.005; RPD: OR 0.04; P ? 9.38 3 10(cid:2)10, HRD: OR 0.30; P ? 0.004) and no-CNV group (RPE atrophy: OR 0.12; P ? 0.005; RPD: OR 0.40, P ? 0.03, HRD: not signi?cant). No differences were detected regarding presence of large drusen, pigmentary abnormalities, and EMD. CONCLUSIONS. A large number of macular drusen in the fellow eye appeared to be characteristic for early onset of NVAMD, whereas RPE atrophy, HRD, and RPD were more frequently present in AMD patients > 80 years. Prospective trials with patients converting to NVAMD are required to further analyze morphologic characteristics for early versus late development of advanced AMD.
关键词： reticular pseudodrusen,fellow eye,spectral-domain optical coherence tomography,neovascular age-related macular degeneration
更新于2025-09-09 09:28:46
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Tuning the optical properties of ZnO:Cd by doping La and Y
摘要： Zinc oxide doped with Cadmium and rare earth elements synthesized by solgel auto combustion route is reported in this work. The studies have been carried out to analyze the structural, morphological and optical properties of Cd doped ZnO and rare earth doped ZnCdO. The XRD analysis reveals that the addition of rare earth impurity decreases the particle size of ZnCdO. La doped ZnCdO has the least particle size among the samples of ZnCdO and rare earth doped ZnCdO. The morphological changes due to the addition of rare earth impurities have been found. Samples of La doped ZnCdO shows a pillar like morphology. The hexagonal structures are prominently seen in the SEM micrographs of the samples of ZnCdO. The UV-Visible spectral analyses show that the bandgap reduces when ZnCdO is doped with the rare earth impurities. The photoluminescence spectra show the broad spectrum in visible region exhibited by ZnO and a scanty UV emission. The UV emission of rare earth doped samples decreases due to the destruction in the crystal structure. The rare earth doped ZnCdO shows a small peak in green emission that decreases when rare earth impurities are doped. There is a uniform spectral response other than a small Gaussian like green peak. The overall analyses show that the samples can be used in optoelectronic applications to work in the visible region.
关键词： rare earth elements,structural properties,optical properties,UV-Visible spectral analyses,Cadmium,SEM micrographs,photoluminescence spectra,XRD analysis,Zinc oxide,solgel auto combustion,morphological properties
更新于2025-09-09 09:28:46
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Effects of Age, Race, and Ethnicity on the Optic Nerve and Peripapillary Region Using Spectral-Domain OCT 3D Volume Scans
摘要： Purpose: To evaluate the effects of age, race, and ethnicity on the optic nerve and peripapillary retina using spectral-domain optical coherence tomography (SD-OCT) three-dimensional (3D) volume scans in normal subjects. Methods: This is a cross-sectional study performed at a single institution in Boston. All patients received retinal nerve fiber layer (RNFL) scans and an optic nerve 3D volume scan. The SD-OCT software calculated peripapillary RNFL thickness, retinal thickness (RT), and retinal volume (RV). Custom-designed software calculated neuroretinal rim minimum distance band (MDB) thickness and area. Results: There were 272 normal subjects, including 175 whites, 40 blacks, 40 Asians, and 17 Hispanics. Rates of age-related decline were 2.3%, 2.0%, 1.7%, 3.3%, and 4.3% per decade for RNFL, RT, RV, MDB neuroretinal rim thickness, and MDB area, respectively. The RNFL was most affected by racial and ethnic variations, with Asians having thicker global, superior, and inferior RNFL, Hispanics having thicker inferior RNFL, and blacks having thinner temporal RNFL, compared to whites. For MDB thickness and area, Asians had smaller nasal values and blacks had smaller temporal values. Peripapillary RT and RV parameters were not influenced by race and ethnicity. Conclusions: All of the parameters exhibited age-related declines. RNFL, MDB thickness, and MDB area demonstrated racial and ethnic variations, while peripapillary RT and RV did not. Translational Relevance: This study demonstrates that both normal aging and ethnicity affect several novel 3D OCT parameters used to diagnose and monitor glaucoma (i.e., RT, RV, and MDB), and this should be factored in when making clinical decisions based on these parameters.
关键词： aging,age,optic nerve,spectral-domain OCT,race,peripapillary retina,three-dimensional OCT
更新于2025-09-09 09:28:46
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Events detection and recognition by the fiber vibration system based on power spectrum estimation
摘要： One of the important successes of optical fiber sensor established for the security system is the detection and the recognition of any type of events. The performance parameters (event recognition, event detection position, and time of detection) are unavoidable and describe the validity of any perimeter detection system. An event recognition is any signal detected within the protected area, and it is related to a non-intrusion event and an intrusion event. To achieve the detection and the recognition events at the real time, an effective two-level vibration recognition method and a technique are proposed and presented in this article. The signal characteristics (short-term energy and short-time over-threshold) have been used and compared to the dynamic threshold to judge the type of event. Then the extraction of the power distribution features on the frequency domain through power spectral estimation on the suspected intrusion signal samples is carried out and finally combined with the time-domain characteristics as feature vector through Support Vector Machine to determine the efficiency and effectiveness of the proposed vibration recognition method. The experimental simulation results show that the proposed method is effective and reliable. With collected data, it can detect and recognize the type of event in real time.
关键词： Support Vector Machine,event detection and recognition,power spectral estimation,Optical fiber sensor,dynamic threshold,short-time over-threshold,short-term energy
更新于2025-09-09 09:28:46
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Hyperspectral based discrimination of thyroid and parathyroid during surgery
摘要： Unintended injuring of anatomical structures during endocrine neck operations can have severe consequences for patient. Especially the nerves and the parathyroid gland can be hard to identify visually. Therefore, intraoperative methods are needed to support the surgeon in this task. Hyperspectral imaging (HSI) is a new approach in the medical area which combines a camera with a spectrometer. The mean absorbance spectra of both glands showed differences in the range between 600 and 700 nm and at 760 and 960 nm. This means that thyroid and parathyroid have different oxygenation states and different contents of deoxygenated hemoglobin and water. From these observations, it is possible to define spectral signatures to characterize both glands. We showed on one patient how spectral signatures can be used in classification algorithms to automatically identify the thyroid and parathyroid from other structures.
关键词： patient data,intraoperative imaging,gastrointestinal operation,classification algorithms,spectral signature
更新于2025-09-09 09:28:46
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Face Recognition System Based on Spectral Graph Wavelet Theory
摘要： This study presents an efficient approach for automatic face recognition based on Spectral Graph Wavelet Theory (SGWT). SGWT is analogous to wavelet transform and the transform functions are defined on the vertices of a weighted graph. The given face image is decomposed by SGWT at first. The energies of obtained sub-bands are fused together and considered as feature vector for the corresponding image. The performance of proposed system is analyzed on ORL face database using nearest neighbor classifier. The face images used in this study has variations in pose, expression and facial details. The results indicate that the proposed system based on SGWT is better than wavelet transform and 94% recognition accuracy is achieved.
关键词： face recognition,spectral graph wavelet theory,Chebyshev polynomial,nearest neighbor classifier
更新于2025-09-09 09:28:46
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[IEEE 2018 Days on Diffraction (DD) - St.Petersburg, Russia (2018.6.4-2018.6.8)] 2018 Days on Diffraction (DD) - Some approaches to harmonic wave propagation in elastic solids with random microstructure
摘要： We address two approaches to the problem of the one-dimensional wave propagation in elastic solids with random microstructure characterized by random elastic and mass properties. They are the method of integral spectral decomposition and the Fokker–Planck–Kolmogorov equation for describing the apparatus of continuous Markov processes. Merits and deficiencies of each approach are discussed. The studied approaches are shown to cover a number of problems of the harmonic wave propagation in heterogeneous or stochastic media. Therefore by means of a preliminary analysis of a particular problem and accounting for the strong and weak side of each approach one can find an appropriate solution strategy.
关键词： Fokker–Planck–Kolmogorov equation,random microstructure,harmonic wave propagation,elastic solids,integral spectral decomposition
更新于2025-09-09 09:28:46