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result(s) for
"Cone classifiers"
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Cone photoreceptor classification in the living human eye from photostimulation-induced phase dynamics
by
Lassoued, Ayoub
,
Crowell, James A.
,
Kurokawa, Kazuhiro
in
Adaptive optics
,
Adult
,
Biological Sciences
2019
Human color vision is achieved by mixing neural signals from cone photoreceptors sensitive to different wavelengths of light. The spatial arrangement and proportion of these spectral types in the retina set fundamental limits on color perception, and abnormal or missing types are responsible for color vision loss. Imaging provides the most direct and quantitative means to study these photoreceptor properties at the cellular scale in the living human retina, but remains challenging. Current methods rely on retinal densitometry to distinguish cone types, a prohibitively slow process. Here, we show that photostimulation-induced optical phase changes occur in cone cells and carry substantial information about spectral type, enabling cones to be differentiated with unprecedented accuracy and efficiency. Moreover, these phase dynamics arise from physiological activity occurring on dramatically different timescales (from milliseconds to seconds) inside the cone outer segment, thus exposing the phototransduction cascade and subsequent downstream effects. We captured these dynamics in cones of subjectswith normal color vision and a deuteranope, and at different macular locations by: (i) marrying adaptive optics to phase-sensitive optical coherence tomography to avoid optical blurring of the eye, (ii) acquiring images at high speed that samples phase dynamics at up to 3 KHz, and (iii) localizing phase changes to the cone outer segment, where photoactivation occurs. Our method should have broad appeal for color vision applications in which the underlying neural processing of photoreceptors is sought and for investigations of retinal diseases that affect cone function.
Journal Article
Improvement of the technological scheme for the enrichment of raw materials containing garnet
2025
Graphite ore is mined at the Zavalliv deposit. An accompanying useful mineral is an abrasive raw material (garnet). Involvement of him in processing will increase the profitability of this enterprise at the expense of obtaining other types of commercial products. As a result of the analysis of processing technologies of raw materials containing garnet, it was established that the high content of clay particles prevents the normal operation of the equipment and does not allow obtaining the necessary indicators of gravity enrichment of raw materials containing garnet. The use of a cone classifier for processing raw materials makes it possible to increase the garnet content in the industrial product by 3-3.5 times compared to the original product. At the same time, there is no clogging of the working area of the equipment, and dusty and clay particles are removed together with the drain the classifier. Additional garnet extraction can be achieved by using a vibro-shock screen after the classifier to separate the +0.1 mm classes, which contain a significant amount of garnet. These results show the prospects of using a classifier and a vibro-impact screen in the technological scheme of enrichment of raw materials containing garnet.
Journal Article
Geodesics in the extended Kähler cone of Calabi-Yau threefolds
by
Ruehle, Fabian
,
Brodie, Callum R.
,
Constantin, Andrei
in
Canonical forms
,
Classical and Quantum Gravitation
,
Classification
2022
A
bstract
We present a detailed study of the effective cones of Calabi-Yau threefolds with
h
1
,
1
= 2, including the possible types of walls bounding the Kähler cone and a classification of the intersection forms arising in the geometrical phases. For all three normal forms in the classification we explicitly solve the geodesic equation and use this to study the evolution near Kähler cone walls and across flop transitions in the context of M-theory compactifications. In the case where the geometric regime ends at a wall beyond which the effective cone continues, the geodesics “crash” into the wall, signaling a breakdown of the M-theory supergravity approximation. For illustration, we characterise the structure of the extended Kähler and effective cones of all
h
1
,
1
= 2 threefolds from the CICY and Kreuzer-Skarke lists, providing a rich set of examples for studying topology change in string theory. These examples show that all three cases of intersection form are realised and suggest that isomorphic flops and infinite flop sequences are common phenomena.
Journal Article
Modeling visual performance differences ‘around’ the visual field: A computational observer approach
by
Carrasco, Marisa
,
Kupers, Eline R.
,
Winawer, Jonathan
in
Algorithms
,
Biology
,
Biology and Life Sciences
2019
Visual performance depends on polar angle, even when eccentricity is held constant; on many psychophysical tasks observers perform best when stimuli are presented on the horizontal meridian, worst on the upper vertical, and intermediate on the lower vertical meridian. This variation in performance 'around' the visual field can be as pronounced as that of doubling the stimulus eccentricity. The causes of these asymmetries in performance are largely unknown. Some factors in the eye, e.g. cone density, are positively correlated with the reported variations in visual performance with polar angle. However, the question remains whether these correlations can quantitatively explain the perceptual differences observed 'around' the visual field. To investigate the extent to which the earliest stages of vision-optical quality and cone density-contribute to performance differences with polar angle, we created a computational observer model. The model uses the open-source software package ISETBIO to simulate an orientation discrimination task for which visual performance differs with polar angle. The model starts from the photons emitted by a display, which pass through simulated human optics with fixational eye movements, followed by cone isomerizations in the retina. Finally, we classify stimulus orientation using a support vector machine to learn a linear classifier on the photon absorptions. To account for the 30% increase in contrast thresholds for upper vertical compared to horizontal meridian, as observed psychophysically on the same task, our computational observer model would require either an increase of ~7 diopters of defocus or a reduction of 500% in cone density. These values far exceed the actual variations as a function of polar angle observed in human eyes. Therefore, we conclude that these factors in the eye only account for a small fraction of differences in visual performance with polar angle. Substantial additional asymmetries must arise in later retinal and/or cortical processing.
Journal Article
Radiomics approach to the condylar head for legal age classification using cone-beam computed tomography: A pilot study
2023
Legal age estimation of living individuals is a critically important issue, and radiomics is an emerging research field that extracts quantitative data from medical images. However, no reports have proposed age-related radiomics features of the condylar head or an age classification model using those features. This study aimed to introduce a radiomics approach for various classifications of legal age (18, 19, 20, and 21 years old) based on cone-beam computed tomography (CBCT) images of the mandibular condylar head, and to evaluate the usefulness of the radiomics features selected by machine learning models as imaging biomarkers. CBCT images from 85 subjects were divided into eight age groups for four legal age classifications: ≤17 and ≥18 years old groups (18-year age classification), ≤18 and ≥19 years old groups (19-year age classification), ≤19 and ≥20 years old groups (20-year age classification) and ≤20 and ≥21 years old groups (21-year age classification). The condylar heads were manually segmented by an expert. In total, 127 radiomics features were extracted from the segmented area of each condylar head. The random forest (RF) method was utilized to select features and develop the age classification model for four legal ages. After sorting features in descending order of importance, the top 10 extracted features were used. The 21-year age classification model showed the best performance, with an accuracy of 91.18%, sensitivity of 80%, and specificity of 95.83%. Radiomics features of the condylar head using CBCT showed the possibility of age estimation, and the selected features were useful as imaging biomarkers.
Journal Article
The extreme rays of the 6×6 copositive cone
by
Afonin Andrey
,
Dickinson, Peter J
,
Hildebrand, Roland
in
Classification
,
Cone classifiers
,
Mathematical analysis
2021
We provide a complete classification of the extreme rays of the 6×6 copositive cone COP6. We proceed via a coarse intermediate classification of the possible minimal zero support set of an exceptional extremal matrix A∈COP6. To each such minimal zero support set we construct a stratified semi-algebraic manifold in the space of real symmetric 6×6 matrices S6, parameterized in a semi-trigonometric way, which consists of all exceptional extremal matrices A∈COP6 having this minimal zero support set. Each semi-algebraic stratum is characterized by the supports of the minimal zeros u as well as the supports of the corresponding matrix-vector products Au. The analysis uses recently and newly developed methods that are applicable to copositive matrices of arbitrary order.
Journal Article
CPT Data Interpretation Employing Different Machine Learning Techniques
2021
The classification of soils into categories with a similar range of properties is a fundamental geotechnical engineering procedure. At present, this classification is based on various types of cost- and time-intensive laboratory and/or in situ tests. These soil investigations are essential for each individual construction site and have to be performed prior to the design of a project. Since Machine Learning could play a key role in reducing the costs and time needed for a suitable site investigation program, the basic ability of Machine Learning models to classify soils from Cone Penetration Tests (CPT) is evaluated. To find an appropriate classification model, 24 different Machine Learning models, based on three different algorithms, are built and trained on a dataset consisting of 1339 CPT. The applied algorithms are a Support Vector Machine, an Artificial Neural Network and a Random Forest. As input features, different combinations of direct cone penetration test data (tip resistance qc, sleeve friction fs, friction ratio Rf, depth d), combined with “defined”, thus, not directly measured data (total vertical stresses σv, effective vertical stresses σ’v and hydrostatic pore pressure u0), are used. Standard soil classes based on grain size distributions and soil classes based on soil behavior types according to Robertson are applied as targets. The different models are compared with respect to their prediction performance and the required learning time. The best results for all targets were obtained with models using a Random Forest classifier. For the soil classes based on grain size distribution, an accuracy of about 75%, and for soil classes according to Robertson, an accuracy of about 97–99%, was reached.
Journal Article
Investigation of sound absorption capability of pine (Pinus densiflora) cone particles
2023
In this study, the sound absorption capability of pine (
Pinus densiflora
) cone particles was investigated as an alternative and eco-friendly, sound-absorbing material. The sound absorption coefficient of pine cone particles was examined after filling impedance tubes with 4, 6, 8, and 10 cm of particles. The sound absorption capability of 4 cm and 6 cm thickness was categorized as 0.5 M class, and that of 8 cm and 10 cm thickness was classed as 0.8 M class according to the KS F 3503 sound-absorbing capability classification of sound-absorbing materials. In particular, 10 cm pine cone particles demonstrated exceptional sound absorption capability in the range of 250–6400 Hz, with an average sound absorption coefficient of 0.6 or greater. In conclusion, pine cone particles were found to have excellent sound absorption capability. Thus, this work suggests that pine cone particles may be useful as an eco-friendly, sound-absorbing material.
Journal Article
Sex classification of first molar teeth in cone beam computed tomography images using data mining
by
Paknahad, Maryam
,
Dokohaki, Sonia
,
Esmaeilyfard, Rasool
in
Accuracy
,
Anthropology
,
Automated classification
2021
•A clinical workflow using machine learning methods is presented to predict the sex.•Naïve Bayesian is the best tool for sex classification.•The first molar teeth had a relatively high accuracy of sex differentiation.•Odontometric parameters can be applied as an additional tool for sex determination.
The teeth have been used as a supplementary tool for sex differentiation as they are resistant to post-mortem degradation. The present study aimed to develop a new novel informatics framework for predicting sex from linear tooth dimension measurements achieved from cone beam computed tomography (CBCT) images.
A clinical workflow using different machine learning methods was employed to predict the sex in the present study. The CBCT images of 485 subjects (245 men and 240 women) were evaluated for sex differentiation. Nine parameters were measured in both buccolingual and mesiodistal aspects of the teeth. We applied our dataset to Naïve Bayesian (NB), Random Forest (RF), and Support Vector Machine (SVM) as classifiers for prediction. Genetic feature selection was used to discover real features associated with sex classification.
The 10-fold cross-validation results indicated that NB had higher accuracy than SVM and RF for sex classification. The genetic algorithm (GA) indicated that the model could fit the data without using the enamel thickness and pulp height. The average classification accuracy of our clinical workflow was 92.31 %.
The results showed that NB was the best method for sex classification. The application of the first molar teeth in sex prediction indicated an acceptable level of sexual classification. Therefore, these odontometric parameters can be applied as an additional tool for sex determination in forensic anthropology.
Journal Article
Effects of a Guide Cone on the Flow Field and Performance of a New Dynamic Air Classifier
2022
A new dynamic air classifier was designed to address the problems of uneven material dispersion and high dust concentration in industrial applications of turbo air classifiers. This paper presents a study on the use of guide cones in the new dynamic air classifier. The ANSYS-Fluent 19.2 software was implemented to simulate the airflow in the dynamic air classifier, and the impact of the guide cone size on the flow field and classification performance of the dynamic air classifier was investigated. The simulation results indicated that with the increase in the guide cone height, the flow field distribution becomes reasonable and the velocity distributions become uniform. When the guide cone height is greater than twice the distance between the guide cone and the bottom of the rotor cage, there is no discernible change in the flow field distribution and classification efficiency. When the guide cone diameter is approximately 0.9 times the diameter of the rotor cage, the airflow pathline is more reasonable, and the flow field and velocity distributions are more uniform. An improper guide cone diameter and height will worsen the classification environment, resulting in a significant decline in classification performance. The material experimental and discrete phase simulation (DPM) showed that DPM can anticipate the changing trends of the cut size and classification accuracy. This study provides theoretical assistance for the structural design and optimization of an air classifier.
Journal Article