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1. Smartphone-Based Pupillometry Using Machine Learning for the Diagnosis of Sports-Related Concussion

Author

Anthony J. Maxin, Bridget M. Whelan, Michael R. Levitt, Lynn B. McGrath, and Kimberly G. Harmon

Subjects
smartphone pupillometry, sports-related concussion, diagnostics, biomarkers, pupillary light reflex, digital health, Medicine (General), R5-920
Abstract

Background: Quantitative pupillometry has been proposed as an objective means to diagnose acute sports-related concussion (SRC). Objective: To assess the diagnostic accuracy of a smartphone-based quantitative pupillometer in the acute diagnosis of SRC. Methods: Division I college football players had baseline pupillometry including pupillary light reflex (PLR) parameters of maximum resting diameter, minimum diameter after light stimulus, percent change in pupil diameter, latency of pupil constriction onset, mean constriction velocity, maximum constriction velocity, and mean dilation velocity using a smartphone-based app. When an SRC occurred, athletes had the smartphone pupillometry repeated as part of their concussion testing. All combinations of the seven PLR parameters were tested in machine learning binary classification models to determine the optimal combination for differentiating between non-concussed and concussed athletes. Results: 93 football athletes underwent baseline pupillometry testing. Among these athletes, 11 suffered future SRC and had pupillometry recordings repeated at the time of diagnosis. In the machine learning pupillometry analysis that used the synthetic minority oversampling technique to account for the significant class imbalance in our dataset, the best-performing model was a random forest algorithm with the combination of latency, maximum diameter, minimum diameter, mean constriction velocity, and maximum constriction velocity PLR parameters as feature inputs. This model produced 91% overall accuracy, 98% sensitivity, 84.2% specificity, area under the curve (AUC) of 0.91, and an F1 score of 91.6% in differentiating between baseline and SRC recordings. In the machine learning analysis prior to oversampling of our imbalanced dataset, the best-performing model was k-nearest neighbors using latency, maximum diameter, maximum constriction velocity, and mean dilation velocity to produce 82% accuracy, 40% sensitivity, 87% specificity, AUC of 0.64, and F1 score of 24%. Conclusions: Smartphone pupillometry in combination with machine learning may provide fast and objective SRC diagnosis in football athletes.

Published
2024
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2. Post-processing of a distributed source method for the localization of somatosensory cortex in a cohort of epilepsy patients

Author

Kevin Tyner, Matthew McCumber, Srijita Das, Carmen Urban, Anthony J. Maxin, Tiffany Chu, Mustaffa Alfatlawi, and Stephen V. Gliske

Subjects
Magnetoencephalography, Somatosensory evoked field, Singular value decomposition, Source localization, Neurosciences. Biological psychiatry. Neuropsychiatry, RC321-571
Abstract

Localizing eloquent cortices is crucial for many neurosurgical applications, such as epilepsy and tumor resections. Clinicians may use non-invasive methods such as magnetoencephalography (MEG) to localize these cortical regions using equivalent current dipoles (ECDs). While dipoles are clinically validated, they provide the estimated strength, location, and orientation of only one or a few sources that best describe the recorded neuromagnetic data, requiring clinicians to make subjective decisions on the spatial extent of the underlying cortical area. More accurate delineation of eloquent cortical areas using distributed source localization methods would provide additional pre-surgical information on these regions’ location and spatial distribution, which could lead to reduced post-surgical complications associated with damage to or removal of eloquent cortices. Our objective in this paper was to present a method to post-process the distributed source localization results to yield a directly interpretable, distributed region of activation. As a test case, we selected somatosensory stimulation in a retrospective cohort of focal and multi-focal epilepsy patients. Our algorithm performs source localization using a distributed method (sLORETA), followed by post-processing and blind source separation to identify the area and boundary of the cortical tissue that primarily activates in response to somatosensory stimulation. We calculated the statistical significance of localization by comparing the identified region to an anatomical atlas and random chance. While examining patients who received left (upper left, UL) and right (upper right, UR) sided median nerve stimulation, the cortical areas identified by the algorithm were in anatomically appropriate areas with a median overlap of 97.6% and 94.7%, respectively. We observe that our algorithm localized somatosensory responses better than random chance in 57/58 (98%) patients who performed the UL task (p

Published
2024
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3. Abstract TP49: The Pupillary Light Reflex Detects Large Vessel Occlusion

Author

Anthony J Maxin, Bernice G Gulek-Bakirci, Do H Lim, Lynn B McGrath, and Michael R Levitt

Subjects
Advanced and Specialized Nursing, Neurology (clinical), Cardiology and Cardiovascular Medicine
Abstract

Introduction: The pupillary light reflex (PLR) is a well-validated biomarker for neurologic monitoring and a decision-making tool for traumatic brain injury patients. We studied a machine learning-based mobile pupillometry platform in patients with acute ischemic stroke (AIS) with a large-vessel occlusion (LVO) prior to thrombectomy, compared to healthy volunteers. Methods: Pupillometry measurements were conducted with a mobile pupillometry platform (PupilScreen) and a digital infrared pupillometer (NeurOptics) for both pre-thrombectomy AIS subjects and healthy volunteers at an academic medical center. To correct for subject age differences, comparisons used the absolute inter-eye difference in each parameter for each subject by measuring the right:left (R:L) eye ratio absolute distance away from 1. Inter-eye difference means across subjects between AIS and healthy cohorts were analyzed for PLR changes in the presence of acute LVO using a t-test for independent means. Results: Seven AIS patients (4 female, 3 male; 1 Hispanic, 6 Caucasian; mean age 60.9 years) and 32 healthy patients (19 female, 13 male; 1 Hispanic, 2 African American, 3 Native American, 5 Asian, 21 Caucasian; mean age 34.4) were enrolled. All LVOs were of the middle cerebral artery, with 3 on the left and 4 on the right. NPi value was above 3 (briskly reactive) for all subjects. However, the smartphone pupillometer demonstrated a statistically significant (p Conclusions: Patients with AIS from LVO demonstrate inter-eye differences in PLR parameters, and mobile pupillometry could be used as a pre-intervention biomarker of AIS in future study. Further investigation in a larger cohort is necessary.

Published
2023
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4. Photodiode nonlinear modeling and its impact on optical links phase noise

Author

A. Rumeau, Loïc Morvan, Olivier Llopis, J. Maxin, G. Cibiel, Z. Abdallah, A. Fernandez, G. Pillet, Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications (LAAS-MOST), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Service Instrumentation Conception Caractérisation (LAAS-I2C), Thales Research and Technology [Palaiseau], THALES, Centre National d'Études Spatiales [Toulouse] (CNES), CNES, DGA, ANR-11-BS04-0029,MiNOToRe,Micro et nano-optomécanique en régime quantique(2011), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), and THALES [France]

Subjects
Physics, Noise temperature, microwave-optics, business.industry, Quantum noise, Shot noise, Y-factor, nonlinear modelling, Noise figure, phase noise, optical fiber link, [SPI]Engineering Sciences [physics], Optics, Noise generator, Phase noise, Electronic engineering, photodiode, CAD, Flicker noise, business
Abstract

International audience; The photodiode impact on the phase noise of an optical link, and particularly its ability to convert the laser amplitude noise into microwave phase noise, is studied and modeled. The model involves a nonlinear RC cell which describes a photogeneration delay which is a function of the optical power. The whole system is then implemented on a microwave CAD software, and the link gain and phase noise performance are computed.

Published
2014
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5. Widely tunable optoelectronic oscillator based on a dual-frequency laser

Author

Daniel Dolfi, G. Pillet, L. Morvan, and J. Maxin

Subjects
Physics, business.industry, Local oscillator, Laser, law.invention, Voltage-controlled oscillator, Laser linewidth, Optics, law, Phase noise, Baseband, Optoelectronics, Heterodyne detection, Photonics, business
Abstract

Summary form only given. Heterodyning of optical modes of a diode-pumped solid-state dual-frequency laser (DFL) is an efficient way to generate optically carried microwave signals [1], that can be used for the distribution of radar local oscillator, coherent or direct detection lidar or the implementation of stable and tunable optoelectronic oscillators. However, the free-running frequency stability of a DFL might be too low for the most demanding applications. We present here the stabilization of the beatnote of an Er, Yb:glass DFL at 1.53 μm with an optical frequency locked loop (OFLL) [2,3].The oscillator is schematized Fig. 1. Used as a voltage controlled oscillator (VCO), the DFL generates a widely tunable microwave signal from 0 to 14 GHz by heterodyning its two orthogonally polarized optical modes. The optical beatnote is detected on two different high-speed photodiodes, the first one directly at the laser output, the second one after an optical fiber coil inducing a delay τ. These two microwave signals are mixed together; we then obtain an error signal which is injected, through a baseband filter, to the DFL frequency control input. This results in the stabilization of the beatnote frequency on a multiple of 1/ τ. 100 m Phase Noise (dBc/Hz)With a 100 m optical fiber delay line, the beatnote phase noise is improved by 60dB leading to a level of -20 dBc/Hz, at 10 Hz from the carrier (Fig. 2), a fairly good result for such a short delay. The beatnote linewidth is then reduced from few hundreds of hertz to few hertz. Since this architecture does not require an RF filter, this oscillator is tunable from 2.5 to 5.5 GHz, actually limited by the RF components of our frequency discriminator. Such an oscillator could be used in a radar, communication or electronic warfare system requiring widely tunable microwave frequency references distributed via photonic links. Moreover, it could find applications in the laser radar area, either by using the wide tunability of the emitted signal to obtain a high range resolution in a direct detection system [4], or by providing a widely tunable local oscillator in a coherent detection lidar.

Published
2013
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6. Widely tunable opto-electronic oscillator based on a dual frequency laser

Author

G. Pillet, Loic Morvan, Olivier Llopis, Daniel Dolfi, Khaldoun Saleh, and J. Maxin

Subjects
Materials science, Optical fiber, business.industry, Amplifier, dBc, Laser, Opto-electronic oscillator, Noise (electronics), law.invention, law, Phase noise, Optoelectronics, business, Telecommunications, Spectral purity
Abstract

We present the stabilization of the beatnote of an Er,Yb:glass Dual Frequency Laser at 1.53 μm with optical fiber delay lines. Instead of standard optoelectronics oscillators, this architecture does not need RF filter and offers a wide tunability from 2.5 to 5.5 GHz. Thank to a fine analysis of the laser RIN to phase noise conversion in the photodiodes, the expected RF-amplifiers noise limit is reached with a phase noise power spectral density of -25 dBc/Hz at 10 Hz (respectively -110 dBc/Hz at 10 kHz) from the carrier over the whole tuning range. Implementation of a double fiber coil architecture improves the oscillator spectral purity: the phase noise reaches a level of -35 dBc/Hz at 10 Hz (respectively -112 dBc/Hz respectively 10 kHz) from the carrier.

Published
2013
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7. Widely tunable opto-electronic oscillator

Author

J. Maxin, Loic Morvan, G. Pillet, and Daniel Dolfi

Subjects
Optical fiber, Materials science, business.industry, Physics::Optics, Delay line oscillator, dBc, Opto-electronic oscillator, Laser, law.invention, Optics, law, Delay-locked loop, Phase noise, business, Microwave
Abstract

We present here a widely tunable opto-electronic oscillator (OEO) based on an Er,Yb:glass Dual Frequency Laser (DFL) at 1.53 μm. The beatnote is stabilized with an optical fiber delay line. Compared to classical optoelectronic oscillators, this architecture does not need RF filter and offers a wide tunability. We measured a reduction of 67 dB of the phase noise power spectral density (PSD) at 10 Hz of the carrier optical fiber leading to a level of -27 dBc/Hz with only 100 m optical fiber. Moreover, the scheme offers a microwave signal tunability from 2.5 to 5.5 GHz limited by the RF components.

Published
2012
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8. Mini and micro-resonators for the generation of high spectral purity microwave signals

Author

L. Morvan, A. Bouchier, Y. Chembo, D. Dolfi, Y. Dumeige, P. Féron, M. Ferrari, L. Larger, E. Le Cren, O. Llopis, J. Maxin, P. Merrer, G. Nunzi Conti, G. Pillet, K. Saleh, P. Salzenstein, F. Van Dijk, G. Cibiel, Thales Research and Technology [Palaiseau], THALES, Service Techniques et Équipements Appliqués à la Microélectronique ( LAAS-TEAM ), Laboratoire d'analyse et d'architecture des systèmes [Toulouse] ( LAAS ), Institut National Polytechnique [Toulouse] ( INP ) -Institut National des Sciences Appliquées - Toulouse ( INSA Toulouse ), Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut National Polytechnique [Toulouse] ( INP ) -Institut National des Sciences Appliquées - Toulouse ( INSA Toulouse ), Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National de la Recherche Scientifique ( CNRS ), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies ( FEMTO-ST ), Université de Technologie de Belfort-Montbeliard ( UTBM ) -Ecole Nationale Supérieure de Mécanique et des Microtechniques ( ENSMM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Fonctions Optiques pour les Technologies de l'informatiON ( FOTON ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Université européenne de Bretagne ( UEB ) -Institut National des Sciences Appliquées - Rennes ( INSA Rennes ) -École Nationale Supérieure des Sciences Appliquées et de Technologie ( ENSSAT ) -Télécom Bretagne-Centre National de la Recherche Scientifique ( CNRS ), Caratterizzazione e Sviluppo di Materiali per la Fotonica e l'Optoelecttronica ( CSMFO ), CNR Istituto di Fotonica e Nanotecnologie [Trento] ( IFN ), Consiglio Nazionale delle Ricerche [Roma] ( CNR ) -Consiglio Nazionale delle Ricerche [Roma] ( CNR ), Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications ( LAAS-MOST ), MDF-Lab ( MDF-Lab, CNR-IFAC ), Consiglio Nazionale delle Ricerche [Roma] ( CNR ) -Istituto di Fisica Applicata 'Nello Carrara' (IFAC), Alcatel-Thalès III-V lab ( III-V Lab ), THALES-ALCATEL, Centre National d'Etudes Spatiales ( CNES ), Centre National d'Etudes Spatiales Action R&T SHYRO R-S10/LN-0001-004, Maurizio Ferrari, Marian Marciniak, Giancarlo C. Righini, Tomasz Szoplik, Stefano Varas, SHYRO, THALES [France], Service Techniques et Équipements Appliqués à la Microélectronique (LAAS-TEAM), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Caratterizzazione e Sviluppo di Materiali per la Fotonica e l'Optoelecttronica (CSMFO), CNR Istituto di Fotonica e Nanotecnologie [Trento] (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications (LAAS-MOST), Istituto di Fisica Applicata 'Nello Carrara' (IFAC), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Alcatel-Thalès III-V lab (III-V Lab), THALES [France]-ALCATEL, Centre National d'Études Spatiales [Toulouse] (CNES), Maurizio Ferrari, Marian Marciniak, Giancarlo C. Righini, Tomasz Szoplik, Stefano Varas, Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne, Consiglio Nazionale delle Ricerche [Roma] (CNR)-Consiglio Nazionale delle Ricerche [Roma] (CNR), and Consiglio Nazionale delle Ricerche [Roma] (CNR)

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [ PHYS.PHYS.PHYS-OPTICS ] Physics [physics]/Physics [physics]/Optics [physics.optics]
Abstract

accessible sur http://minap2012.fbk.eu; International audience; Optoelectronic Oscillators (OEOs) are an attractive alternative to electrical solutions for the generation of high spectral purity signal at high frequency. Indeed, carrying the microwave signal on an optical carrier offers the opportunity of long staorage time, with almost no dependence on signal frequency. For example, classical OEOs are based on kilometre long fiber delays and, in a relative simple setup, their performances exceed the ones of most microwave oscillators. However, the most promising OEOs architectures, in term of performances and integration level, are based on high Q optical resonators. After an introduction on the principle of OEOs and their various potential applications in advanced microwave systems, we will present recent results that we have obtained in this field.. First, the realization and characterization of silica, CaF2, MgF2 and LiNbO3 Whispering Gallery Modes (WGM) resonators with Q factors in the 10^8-10^9 range will be presented, together with related light coupling techniques for their practical use in OEOs demonstrations. Then the realization and characterization of fiber-ring resonators, that present Q factors exceeding 10^9 in a relatively simple architecture will be highlighted. Finally, dual-frequency laser sources that have been specifically realized for OEOs will be described.

Published
2012

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