ZnGeP2 crystals with different thermal spraying of the chemical elements on the crystal surface studied in this work. The Raman spectra of the crystals were obtained using the inVia Reflex system with an excitation wavelength of 785 nm. Good separation between ZnGeP2 and Ca/Mg samples by first principal component points to the significant differences in corresponding Raman spectral features. Proposed machine learning pipeline include principal component analysis and support vector machine with non-linear radial based function kernel. High area under curve values also reflects good pairwise separability of the samples.
Machine learning methods have found applications in areas such as security, molecular biology, medicine, computational physics and mechanics, etc. In this paper a review on using machine learning technologies for LIDAR measurements is present based on Google Scholar, Scopus, and Web of Science citing databases. Search includes keywords “lidar”, “atmospheric sensing”, “machine learning” through past 5 years. Most relevant and significant papers were selected.
ZnGeP2 crystals with different optical breakdown thresholds studied in this work. The Raman spectra of the crystals were obtained using the inVia Reflex system with an excitation wavelength of 785 nm. It is shown that the obtained peaks at frequencies of 141.6, 203.3, 327.4, and 402.4 cm–1 correspond to the vibrational frequencies of the ZnGeP2 lattice for wafers cut parallel to the (100) crystallographic directions and the peaks at frequencies of 119.1, 245, 327.4, 357.1, 384.7, and 408.7 cm–1 to the (001) crystallographic directions. No correlation with the breakdown threshold was found. This fact confirms the assumption that the breakdown threshold in a given spectral range is determined not by thermal mechanisms, but by the dielectric breakdown of the crystal surface. This work was supported by the Ministry of Science and Higher Education of the Russian Federation (V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Sciences).
Terahertz medical imaging is an expanding field of research in the diagnosis of several medical conditions, including wound healing. Study was carried out in rat models where a THz imaging system was used to mark the difference in absorption spectra between a wound and a healthy tissue. Absorption spectra of the wound and healthy tissues have been measured in the 0.3-1.5 THz range.
The terahertz (THz) attenuated total reflectance (ATR) imaging of normal and pathological skin under the action of various dehydration agents was carried out in vivo. Studies were conducted on animal models (the mouse), patients with diabetes, and healthy volunteers. For measurements, each animal was leaned against the ATR prism of the skin surface, and several locations in the skin of each animal were analyzed. Places on the skin for analysis were chosen so that the intensity spectra of the THz signal were practically the same for selected points. THz spectra measurements were carried out every 10 minutes within 45 minutes interval under the action of a dehydration agent. 40% glucose was shown to provide the most effective improving tissue optical clearing effect in the THz range.
The ability of diagnostics of melanoma and nevus based on spectral analysis of paraffin-embedded tissues in the 0.3-1.5 terahertz (THz) range has been carried out. The principal component analysis was applied to reduce the dimension of the feature space. A comparison of these spectra shows evident differences between samples. The possibility of applying the optical clearing to paraffin-embedded tissue for improving the visualization of the internal structure of tissue for diagnostic and research purposes is shown. In the studies, a sufficiently strong effect of optical clearing of paraffin-embedded muscle was obtained (63%).
The results of the comparative analysis of exhaled air samples from patients with diabetes mellitus second type (target group) and healthy volunteers (control group) with using laser optical-acoustic IR spectroscopy are presented. The measured absorption spectra of exhaled air samples visualization were performed using the principal component analysis. The good spatial separation of the target and control groups in the space of the main components was achieved, which indicates a significant change in the composition and concentration of metabolites in the exhaled air of patients with diabetes. The volatile metabolites that may be characteristic of diabetes are also discussed.
The quasi-static compression optical coherence elastography (OCE) is used to find Young’s modulus of human skin1,2 . The data on the layers of human skin deformation in vivo were obtained and analyzed. In the OCE compression method, a calibration layer with a known Young's modulus was used, which made it possible to identify the value of the volunteers' skin elastic modulus.
The results of a comparative study of an emanation from the skin of patients with diabetes mellitus and healthy volunteers using THz spectroscopy. A technique for collecting and analyzing emanation samples from the skin has been developed, and its applicability in THz spectroscopy has been demonstrated. Good separation of THz spectra of the skin emanations has been shown for the target and control groups by the principal component analysis. It shows that THz spectroscopy of skin emanations is useful for the diagnosis of diabetes mellitus.
The changes in the stiffness modulus of collagen structures in a collagen phantom were studied using optical coherent elastography (OCE). The disorganization of the phantom collagen fibers was obtained by mechanical action (twisting). Young's modulus values were measured for various phantom density values using the compression OCE method.
Low-level laser exposure is a non-invasive and less painful method, which is used as an alternative method to classical acupuncture with metal needles and could be applied in clinical medical practice. The study of the laser acupuncture effect on the electroencephalogram (EEG) characteristics was carried out. The electrodes were located on the surface of the subject's head according to the standard scheme 10-20. Experimental EEG data were obtained by standard digital 16-channel electroencephalograph with EEG18 V5.0.3 software. The EEG frequencies in each of the measurements have been analyzed. This work shows that low-level laser stimulation able to change the power of rhythms in the head areas, which corresponds to the stimulation of different brain regions.
The of multiphoton microscopy (MPM) based on two-photon fluorescence and second-harmonic generation is promising for diagnosing neoplastic transformation of tissues. The results of MPM studies of tissues with prostate adenocarcinoma embedded in paraffin blocks are presented. The tissue fluorescence was also analyzed using the fluorescence lifetime (Fluorescence-lifetime imaging microscopy - FLIM) option. The relationships between the fluorescence peculiarities and the second harmonic generation of the prostate gland tissues were obtained for different morphological images.
Last years the development of computer-aided diagnostic systems for medical image analysis has become a hot topic. A key step is connected with informative features extraction. Here, we discussed multiphoton microscopy and optical coherent tomography lymphedema tissue images analysis using gradient processing methods.
This work is devoted to the development of the approach to restoration of the spatial-temporal distribution of electric field in the human brain. This field was estimated from the model derived from the Maxwell’s equations with boundary conditions corresponding to electric potentials at the EEG electrodes, which are located on the surface of the head according to the standard “10-20” scheme. The MRI data were used for calculation of the spatial distribution of the electrical conductivity of biotissues in the human brain. The study of the electric field distribution using our approach was carried out for the healthy child and the child with autism. The research was carried out using the equipment of the Tomsk Regional Common Use Center of Tomsk State University.
KEYWORDS: Colorectal cancer, Blood, Plasma, Cancer, Simulation of CCA and DLA aggregates, Absorption, Terahertz radiation, Statistical analysis, Laser spectroscopy, Tumors
The study of exosomes of saliva and blood plasma by THz laser spectroscopy was carried out. Exosomes were sampled from patients with colorectal cancer (n = 6) and healthy volunteers (n = 5). A substantive examination of the samples absorption spectra was performed using the method of canonical correlation analysis. The presence of Glycine, LAlanine, Mannose was revealed everywhere. The Mannose content was less in exosomes samples corresponding to colorectal cancer in comparison with exosomes samples from healthy volunteers.
Absorption spectra of paraffin-embedded prostate cancer and healthy tissues have been measured in the 0.2-3 THz range. The Principal Component Analysis and the Support Vector Machine (SVM) were applied to analyze experimental data. The SVM classifier was created which allows to distinguish the healthy tissues from tumor tissues, including classification of tumor tissue stage according to the Gleason scale.
In this work we studied applicability of the laser spectroscopy for fixing differences in composition of exhaled air depending on the position of the body in different physical states. Using principal component analysis we show that the use of the laser spectroscopy methods is sufficiently effective to solve this problem and provide additional opportunities for the comprehensive study of the human condition.
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