- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Changes in Retinal Nerve Fiber Layer Reflectance Intensity as a Predictor of Functional Progression in Glaucoma
摘要： PURPOSE. We determined whether longitudinal changes in retinal nerve fiber layer (RNFL) reflectance provide useful prognostic information about longitudinal changes in function in glaucoma. METHODS. The reflectance intensity of each pixel within spectral-domain optical coherence tomography (SD-OCT) circle scans was extracted by custom software. A repeatability cohort comprising 53 eyes of 27 participants (average visual field mean deviation [MD] (cid:2)1.65 dB) was tested five times within a few weeks. To minimize test–retest variability in their data, a reflectance intensity ratio was defined as the mean reflectance intensity of pixels within the RNFL divided by the mean between the RNFL and RPE. This was measured in a separate longitudinal cohort comprising 310 eyes of 205 participants tested eight times at 6-month intervals (average MD, (cid:2)0.99 dB; median rate of change, (cid:2)0.09 dB/y). The rate of change of this ratio, together with the rate of RNFL thinning, and their interaction, were used to predict the rate of change of MD. RESULTS. In univariate analyses, the rate of RNFL thinning was predictive of the rate of MD change (P < 0.0001), but the rate of change of reflectance intensity ratio was not (P ? 0.116). However, in a multivariable model, the interaction between these two rates significantly improved upon predictions of the rate of functional change made using RNFL thickness alone (P ? 0.038). CONCLUSIONS. For a given rate of RNFL thinning, a reduction in the RNFL reflectance intensity ratio is associated with more rapid functional deterioration. Incorporating SD-OCT reflectance information may improve the structure–function relation in glaucoma.
关键词： RNFL,reflectance,OCT
更新于2025-09-23 15:21:01
-
Diffuse Reflectance Spectroscopy (Vis-Nir-Swir) as a Promising Tool for Blue Carbon Quantification in Mangrove Soils: A Case of Study in Tropical Semiarid Climatic Conditions
摘要： The assessment of the soil organic carbon (SOC) stocks in mangrove ecosystems is essential for coastal management activities seeking the mitigation of CO2 emissions. However, the wet chemical analysis conventionally used to quantify SOC may overestimate SOC content due to oxidation of reduced compounds. This work focused on the use of diffuse reflectance spectroscopy (DRS) for predicting SOC in mangrove forest areas. When used properly, DRS may be, in some cases, a more accurate and more efficient method for the determination of SOC in mangrove soils than conventional analytical approaches. Furthermore, variable selection may simplify and improve prediction accuracy, reducing collinearity in the dataset used and allowing better SOC quantification through more interpretable and robust models.
关键词： Tropical semiarid climatic conditions,Mangrove soils,Vis-NIR-SWIR,Blue Carbon,Diffuse reflectance spectroscopy
更新于2025-09-23 15:21:01
-
Spectroscopic Characterization of Emulsions Generated with a New Laser-Assisted Device
摘要： This paper presents a spectroscopic study of emulsions generated with a laser-assisted device. Fourier transform infrared (FTIR), Raman and UV–Vis–NIR reflectance spectra of emulsions, recorded before and after exposure to laser radiation were used to characterize the effect of laser irradiation. The paper also presents a comparison between the calculated IR spectra and the experimental FTIR spectra of an emulsion’s components. FTIR measurements allowed the identification of absorption bands specific to each of the emulsions’ components. Moreover, it enabled the observation of destabilization of the emulsion in real-time. Raman spectroscopy allowed the observation of the modifications at a molecular level, by identifying the vibrations of the representative functional groups and the polymerization of sodium tetradecyl sulfate (STS) molecules by analyzing the evolution of the carbonyl band. UV–Vis–NIR reflectance spectra of emulsions before and after exposure to laser radiation showed that the physical characteristics of the emulsions changed during irradiation—the dimensions of the droplets decreased, leading to an emulsion with a better time stability. These results proved that the employed spectroscopy techniques were powerful tools in emulsion analysis.
关键词： UV–Vis–NIR reflectance spectroscopy,FTIR spectroscopy,emulsion,Raman spectroscopy
更新于2025-09-23 15:19:57
-
Optical Classification of the Remote Sensing Reflectance and Its Application in Deriving the Specific Phytoplankton Absorption in Optically Complex Lakes
摘要： Optical water types (OWTs) were identified from remote sensing reflectance (Rrs(λ)) values in a field-measured dataset of several large lakes in the lower reaches of the Yangtze and Huai River (LYHR) Basin. Four OWTs were determined from normalized remote sensing reflectance spectra (NRrs(λ)) using the k-means clustering approach, and were identified in the Sentinel 3A OLCI (Ocean Land Color Instrument) image data over lakes in the LYHR Basin. The results showed that 1) Each OWT is associated with different bio-optical properties, such as the concentration of chlorophyll-a (Chla), suspended particulate matter (SPM), proportion of suspended particulate inorganic matter (SPIM), and absorption coefficient of each component. One optical water type showed an obvious characteristic with a high contribution of mineral particles, while one type was mostly determined by a high content of phytoplankton. The other types belonged to the optically mixed water types. 2) Class-specific Chla inversion algorithms performed better for all water types, except type 4, compared to the overall dataset. In addition, class-specific inversion algorithms for estimating the Chla-specific absorption coefficient of phytoplankton at 443 nm (a*ph(443)) were developed based on the relationship between a*ph(443) and Chla of each OWT. The spatial variations in the class-specific model-derived a*ph(443) values were illustrated for 2 March 2017, and 24 October 2017. 3) The dominant water type and the Shannon index (H) were used to characterize the optical variability or similarity of the lakes in the LYHR Basin using cloud-free OLCI images in 2017. A high optical variation was located in the western and southern parts of Lake Taihu, the southern part of Lake Hongze, Lake Chaohu, and several small lakes near the Yangtze River, while the northern part of Lake Hongze had a low optical diversity. This work demonstrates the potential and necessity of optical classification in estimating bio-optical parameters using class-specific inversion algorithms and monitoring of the optical variations in optically complex and dynamic lake waters.
关键词： specific inherent optical properties,optical water types,remote sensing reflectance,Sentinel 3A/OLCI
更新于2025-09-19 17:15:36
-
Apport de la microscopie confocale par réflectance et de l’OCT dans le diagnostic d’un carcinome basocellulaire nodulaire kystique
摘要： The role of reflectance confocal microscopy and OCT in the diagnosis of nodular kystic BCC
关键词： Basal cell carcinoma,Noninvasive imaging,Optical coherence tomography,In vivo confocal microscopy,Dermoscopy,In vivo reflectance confocal microscopy,Cystic basal cell carcinoma
更新于2025-09-19 17:15:36
-
Atmospheric particulate matter characterization by Fourier transform infrared spectroscopy: a review of statistical calibration strategies for carbonaceous aerosol quantification in US measurement networks
摘要： Atmospheric particulate matter (PM) is a complex mixture of many different substances and requires a suite of instruments for chemical characterization. Fourier transform infrared (FT-IR) spectroscopy is a technique that can provide quantification of multiple species provided that accurate calibration models can be constructed to interpret the acquired spectra. In this capacity, FT-IR spectroscopy has enjoyed a long history in monitoring gas-phase constituents in the atmosphere and in stack emissions. However, application to PM poses a different set of challenges as the condensed-phase spectrum has broad, overlapping absorption peaks and contributions of scattering to the mid-infrared spectrum. Past approaches have used laboratory standards to build calibration models for prediction of inorganic substances or organic functional groups and predict their concentration in atmospheric PM mixtures by extrapolation. In this work, we review recent studies pursuing an alternate strategy, which is to build statistical calibration models for mid-IR spectra of PM using collocated ambient measurements. Focusing on calibrations with organic carbon (OC) and elemental carbon (EC) reported from thermal–optical reflectance (TOR), this synthesis serves to consolidate our knowledge for extending FT-IR spectroscopy to provide TOR-equivalent OC and EC measurements to new PM samples when TOR measurements are not available. We summarize methods for model specification, calibration sample selection, and model evaluation for these substances at several sites in two US national monitoring networks: seven sites in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network for the year 2011 and 10 sites in the Chemical Speciation Network (CSN) for the year 2013. We then describe application of the model in an operational context for the IMPROVE network for samples collected in 2013 at six of the same sites as in 2011 and 11 additional sites. In addition to extending the evaluation to samples from a different year and different sites, we describe strategies for error anticipation due to precision and biases from the calibration model to assess model applicability for new spectra a priori. We conclude with a discussion regarding past work and future strategies for recalibration. In addition to targeting numerical accuracy, we encourage model interpretation to facilitate understanding of the underlying structural composition related to operationally defined quantities of TOR OC and EC from the vibrational modes in mid-IR deemed most informative for calibration. The paper is structured such that the life cycle of a statistical calibration model for FT-IR spectroscopy can be envisioned for any substance with IR-active vibrational modes, and more generally for instruments requiring ambient calibrations.
关键词： thermal-optical reflectance,statistical calibration,elemental carbon,IMPROVE network,Chemical Speciation Network,FT-IR spectroscopy,organic carbon,atmospheric particulate matter
更新于2025-09-19 17:15:36
-
Response of the Retinal Nerve Fiber Layer Reflectance and Thickness to Optic Nerve Crush
摘要： PURPOSE. To study the effects of acute optic nerve damage on the re?ectance of the retinal nerve ?ber layer (RNFL) and to compare the time courses of changes of RNFL re?ectance and thickness. METHODS. A rat model of optic nerve crush (ONC) was compared with previously studied normal retinas. The re?ectance and thickness of the RNFL were studied at 1 to 5 weeks after ONC. Re?ectance spectra from 400 to 830 nm were measured for eyes with ONC, their contralateral untreated eyes, and eyes with sham surgery. Directional re?ectance was studied by varying the angle of incidence. RNFL thickness was measured by confocal microscopy. RESULTS. After ONC, the RNFL re?ectance remained directional. At 1 week, RNFL re?ectance decreased signi?cantly at all wavelengths (P < 0.001), whereas there was no signi?cant change in RNFL thickness (P ? 0.739). At 2 weeks, both RNFL re?ectance and thickness decreased signi?cantly, and by 5 weeks they declined to approximately 40% and 30%, respectively, of the normal values. Although RNFL re?ectance decreased at all wavelengths, there was a greater reduction at short wavelengths. Spectral shape at long wavelengths was similar to the normal. Some of these changes were also found in the contralateral untreated eyes, but none of these changes were found in eyes with sham surgery. CONCLUSIONS. Decrease of RNFL re?ectance after ONC occurs prior to thinning of the RNFL and the decrease is more prominent at short wavelengths. Direct measurement of RNFL re?ectance, especially at short wavelengths, may provide early detection of axonal damage.
关键词： optic nerve crush,optical properties,thinning of the RNFL,directional reflectance,retinal nerve fiber layer
更新于2025-09-19 17:15:36
-
[Communications in Computer and Information Science] Advances in Signal Processing and Intelligent Recognition Systems Volume 968 (4th International Symposium SIRS 2018, Bangalore, India, September 19–22, 2018, Revised Selected Papers) || Pre-processed Hyperspectral Image Analysis Using Tensor Decomposition Techniques
摘要： Hyperspectral remote sensing image analysis has always been a challenging task and hence there are several techniques employed for exploring the images. Recent approaches include visualizing hyperspectral images as third order tensors and processing using various tensor decomposition methods. This paper focuses on behavioural analysis of hyperspectral images processed with various decompositions. The experiments includes processing raw hyperspectral image and pre-processed hyperspectral image with tensor decomposition methods such as, Multilinear Singular Value Decomposition and Low Multilinear Rank Approximation technique. The results are projected based on relative reconstruction error, classification and pixel reflectance spectrums. The analysis provides correlated experimental results, which emphasizes the need of pre-processing for hyperspectral images and the trend followed by the tensor decomposition methods.
关键词： Low Multilinear Rank Approximation,Remote sensing image,Pixel reflectance spectrums,Multilinear Singular Value Decomposition,Relative reconstruction error,Tensor decomposition
更新于2025-09-19 17:15:36
-
High-speed light source depth estimation using spatially-resolved diffuse imaging
摘要： We describe a system for high-speed depth estimation of a light source embedded in a scattering medium. A polynomial model estimates source depth from the spatially-resolved, diffuse reflectance profile measured with a fibre optic probe on the surface of a scattering medium. A dataset of Monte Carlo reflectance profiles is generated over a range of typical optical properties and the model is fit to the simulated reflectance at four detector locations. The model accounts for a source depth up to 15 mm. Cross-validation using the Monte Carlo dataset produced a root mean square error of 0.12 mm. Experimental reflectance data is acquired with the detector probe, which consists of four optical fibres mounted in a black acetal plastic disk. The optical fibres are coupled into avalanche photodiodes for high-speed acquisition of the reflectance profile. When applied to measurements from a tissue-mimicking phantom with an embedded light source, the polynomial model generates depth estimates within 2 mm of the true depth, up to a source depth of 15 mm.
关键词： source location,Monte Carlo simulation,tissue optics,turbid media,diffuse reflectance
更新于2025-09-19 17:15:36
-
Microneedle fractional radiofrequency-induced micropores evaluated by in vivo reflectance confocal microscopy, optical coherence tomography, and histology
摘要： Background: Microneedle fractional radiofrequency (MNRF) is a minimally invasive technique that delivers radiofrequency (RF) energy into the skin via microneedles. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) enable the characterization of device-tissue interactions in in vivo skin. The aim of this study is to describe MNRF-induced micropores using RCM and OCT imaging. Materials and methods: Five healthy participants were treated with a 7 × 7 array of 1500 μm microneedles on two adjacent areas of the right hip. One area received MNRF using high RF energy while the other underwent MNRF at low RF energy. Micropore morphology was evaluated qualitatively and quantitatively with RCM and OCT. To relate imaging with histology, one participant underwent punch biopsy in both areas. Results: Reflectance confocal microscopy visualized shape, content, and thermal-induced coagulation zone (CZ) of MNRF micropores. At high RF energy, micropores showed concentric shape, contained hyperreflective granules, and coagulated tissue from epidermis to dermo-epidermal junction (diameter 63-85 μm). Micropores at low RF energy, presented with a stellate shape, no content and CZs that were visible only in epidermis (CZ thickness 9 μm, IQR 8-21 μm). Evaluating OCT, high RF energy showed deeper (150 μm), more easily identifiable micropores compared to low RF energy micropores (70 μm). Histology showed tissue coagulation to a depth of 1500 μm at high RF energy, while at low RF energy, disruption was only visible in epidermis. Conclusion: Microneedle fractional radiofrequency micropores show distinct characteristics in both RCM and OCT, depending on RF energy. These in vivo imaging modalities are complementary and allow combined, qualitative, and quantitative evaluation.
关键词： microneedle fractional radiofrequency,histology,optical coherence tomography,micropore,reflectance confocal microscopy
更新于2025-09-19 17:15:36