Monitoring temporal opacity fluctuations of large structures with muon tomography : a calibration experiment using a water tower tank

Usage of secondary cosmic muons to image the geological structures density distribution significantly developed during the past ten years. Recent applications demonstrate the method interest to monitor magma ascent and volcanic gas movements inside volcanoes. Muon radiography could be used to monitor density variations in aquifers and the critical zone in the near surface. However, the time resolution achievable by muon radiography monitoring remains poorly studied. It is biased by fluctuation sources exterior to the target, and statistically affected by the limited number of particles detected during the experiment. The present study documents these two issues within a simple and well constrained experimental context: a water tower. We use the data to discuss the influence of atmospheric variability that perturbs the signal, and propose correction formulas to extract the muon flux variations related to the water level changes. Statistical developments establish the feasibility domain of muon radiography monitoring as a function of target thickness (i.e. opacity). Objects with a thickness comprised between $\simeq$ 50 $\pm$ 30m water equivalent correspond to the best time resolution. Thinner objects have a degraded time resolution that strongly depends on the zenith angle, whereas thicker objects (like volcanoes) time resolution does not.Comment: 11 pages, 9 figures. Final version published in Scientific Reports, Nature, 14 march 201

Emotion facial recognition by the means of automatic video analysis

International audienceThe elderly population has been growing dramatically and future predictions and estimations showcase that by 2050 the number of people over 65 years old will increase by 70%, the number of people over 80 years old will increase by 170%, outnumbering younger generations from 0-14 years. Other studies indicate that around half of the current population of over 75 year olds suffer from physical and / or mental impairments and as a result are in need of high level of care. The loss of autonomy can be delayed by maintaining an active life style, which also would lead to reduced healthcare financial costs. With the expected increase of the world elderly population, and on the other hand limited available human resources for care a question arises as ”How can we improve health care in an efficient and cost effective manner? “.Motivated by the above, we propose an approach for detecting facial expressions in Alzheimer’s patients that can be a pertinent unit in an automated assisted living system for elderly subjects. Specifically, we have collected video-data of Alzheimer’s patients in musical mnemotherapy, where even patients suffering from apathy exhibit a number of emotions and expressions.Methods: We propose a novel spatio-temporal algorithm for facial emotion and expression recognition, based on dense trajectories, bag of features and support vector machine classification. We compare the proposed algorithm to a facial-landmark-based algorithm concerning signal displacement of tracked points within the face.Challenging for these algorithms (and specifically for the latter) has been the unconstrained setting involving Alzheimer’s patients in musical mnemotherapy and interviews. We have recorded data at the Alzheimer’s center Fondation G.S.F Jean Louis Noisiez in Biot from multiple therapy-sessions that serves to validate our method. The proposed system differentiates between four different facial expressions, namely neutral, smile, sad and talking.One expected benefit for Alzheimer’s patients is that positive emotions and their cause could be determined and replicated in order to increase life standard for such patients, which also brings to the fore a delay in the development of Alzheimer’s

Expression Recognition for Severely Demented Patients in Music Reminiscence-Therapy

International audienceRecognizing expressions in severely demented Alzheimer's disease (AD) patients is essential, since such patients have lost a substantial amount of their cognitive capacity, and some even their verbal communication ability (e.g., aphasia). This leaves patients dependent on clinical staff to assess their verbal and non-verbal language, in order to communicate important messages, as of the discomfort associated to potential complications of the AD. Such assessment classically requires the patients' presence in a clinic, and time consuming examination involving medical personnel. Thus, expression monitoring is costly and logistically inconvenient for patients and clinical staff, which hinders among others large-scale monitoring. In this work we present a novel approach for automated recognition of facial activities and expressions of severely demented patients, where we distinguish between four activity and expression states, namely talking, singing, neutral and smiling. Our approach caters to the challenging setting of current medical recordings of music-therapy sessions, which include continuous pose variations, occlusions, camera-movements, camera-artifacts, as well as changing illumination. Additionally and importantly, the (elderly) patients exhibit generally less profound facial activities and expressions in a range of intensities and predominantly occurring in combinations (e.g., talking and smiling). Our proposed approach is based on the extension of the Improved Fisher Vectors (IFV) for videos, representing a video-sequence using both, local, as well as the related spatio-temporal features. We test our algorithm on a dataset of over 229 video sequences, acquired from 10 AD patients, with promising results, which have sparked substantial interest in the medical community. The proposed approach can play a key role in assessment of different therapy treatments, as well as in remote large-scale healthcare-frameworks

ENREGISTREMENT DES TEMPS D'IMMERSION A DIFFÉRENTS NIVEAUX, DUS AUX NAPPES D'EAU INDUITES PAR LES VAGUES SE BRISANT SUR UNE PAROI ROCHEUSE

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ENREGISTREMENT DES TEMPS D'IMMERSION A DIFFÉRENTS NIVEAUX, DUS AUX NAPPES D'EAU INDUITES PAR LES VAGUES SE BRISANT SUR UNE PAROI ROCHEUSE

International audienc