109 research outputs found
A time-frequency approach to blind deconvolution in multipath underwater channels
Blind deconvolution is presented in the underwater acoustic channel context, by time-frequency processing. The acoustic propagation environment was modelled as a multipath propagation channel. For noiseless simulated data, source signature estimation was performed by a model-based method. The channel estimate was obtained via a time-frequency formulation of the conventional matched-filter. Simulations used a ray-tracing physical model, initiated with at-sea recorded environmental data, in order to produce realistic underwater channel conditions. The quality of the estimates was 0.793 for the source signal, and close to I for the resolved amplitudes and time-delays of the impulse response. Time-frequency processing has proved to overcome the typical ill-conditioning of single sensor deterministic deconvolution techniques
Optimal design of a whale of anti-collision system
This paper summerizes tools coming from estimationâs theory to evaluate and design experimental device. Theses tools
are applied to the "Whale Anti Collision System" dedicated to localise Sperm Whales and to avoid collision with ships.
Relying on theoretical tools, our approach tries to be as close as possible of reality by using true sperm clicks, realistic
measurement noise by allowing sensors and acoustic environmental missknowledges. Without any acoustic
environmental assesment, WACS system shows to be a good tool for biology study but may not be enougth accurate to
be included in a anti-collision network. With an acoustic environmental assesment, WACS system is accurate enough to
be included in an anti-collision network. WACS settings and step of the anti-collision network are identified.Dans cet article, des outils issus de la thĂ©orie de lâestimation sont proposĂ©s pour permettre lâĂ©valuation des
performances et le dimensionnement de systÚmes expérimentaux. Ceux-ci ont été appliqués au systÚme
WACS (Whales Anti Collision System), systĂšme de localisation passive des cachalots vocalisants ou non afin de
contribuer Ă rĂ©duire les collisions avec les navires. BasĂ©e sur des outils thĂ©oriques, lâapproche proposĂ©e
sâattache Ă se rapprocher au mieux de la rĂ©alitĂ© par les hypothĂšses effectuĂ©es. Sans monitorage de
lâenvironnement acoustique, il est dĂ©montrĂ© que WACS est un bon outil pour le biologiste mais pourraĂźt ne pas
ĂȘtre assez prĂ©cis pour ĂȘtre insĂ©rĂ© au sein dâun rĂ©seau anti-collision. AssociĂ© Ă un monitorage de
lâenvironnement acoustique, il est dĂ©montrĂ© que WACS est assez prĂ©cis pour ĂȘtre inclus dans un rĂ©seau
anti-collision, les degrés de liberté de WACS sont optimisés et la maille du réseau est identifiée
ILC Beam Energy Measurement by means of Laser Compton Backscattering
A novel, non-invasive method of measuring the beam energy at the
International Linear Collider is proposed. Laser light collides head-on with
beam particles and either the energy of the Compton scattered electrons near
the kinematic end-point is measured or the positions of the Compton
backscattered -rays, the edge electrons and the unscattered beam
particles are recorded. A compact layout for the Compton spectrometer is
suggested. It consists of a bending magnet and position sensitive detectors
operating in a large radiation environment. Several options for high spatial
resolution detectors are discussed. Simulation studies support the use of an
infrared or green laser and quartz fiber detectors to monitor the backscattered
photons and edge electrons. Employing a cavity monitor, the beam particle
position downstream of the magnet can be recorded with submicrometer precision.
Such a scheme provides a feasible and promising method to access the incident
beam energy with precisions of or better on a bunch-to-bunch basis
while the electron and positron beams are in collision.Comment: 47 pages, 26 figures, version as accepted by Nucl. Instr. Meth. A
after improvement
Passive geoacoustic inversion of very shallow water environment with ship's noise: incoherent processing
In the context of the passive geoacoustic inversion, this manuscript proposes a new Inversion Method suitable for very
shallow water environments (10 to 30 m) from the broadband noise produced by ships of opportunity. The solution is
dedicated to a small number of hydrophones and is easy to implement. The interference patterns generated by the ship
movement and the propagation properties are exploited to extract the relative dispersion curves on a chosen bandwidth
then the geoaoustic inversion is performed. Here, we describe our algorithms and validate them on realistic synthetic data as well as on real data from a very shallow water trial performed off the Southern coast of Barcelona, Spain.
Valuable results are obtained and allow to draw some way of improvement.Dans le contexte de l'inversion géoacoustique passive, nous proposons une méthode d'estimation
des propriétés acoustiques d'un canal océanique trÚs petits fonds (profondeur de 10 à 30 m) à partir du bruit
large bande rayonné par des navires en transit. La solution est développée afin de conduire à un systÚme de
mesure minimisant le nombre d'hydrophones requis, pour cela elle utilise le mouvement des sources. Ă partir
de l'observation acoustique de radiales centrées sur un hydrophone, les phénomÚnes d'interférences entre
modes de propagation sont utilisés pour extraire les courbes de dispersion relatives du canal sur une bande
fréquentielle choisie entre 50 et 500Hz. La contribution d'un navire est alors inversée pour fournir les
propriétés du canal. Une description des algorithmes et de leurs implémentations est effectuée et leurs
validations sont envisagées sur des données synthétiques réalistes ainsi que sur des données réelles issues
d'une campagne expérimentale trÚs petits fonds (profondeur~20 m) réalisée au sud de Barcelone à partir de
petits navires d'opportunité constitués principalement de chalutiers. Les résultats produits sont encourageants
et permettent de dresser des perspectives d'amélioration pour la méthode
proposée
Measuring hearing in wild beluga whales
Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in "The Effects of Noise on Aquatic Life II," edited by Arthur N. Popper, Anthony Hawkins, 729-735. New York, NY: Springer, 2016. doi: 10.1007/978-1-4939-2981-8_88.We measured the hearing abilities of seven wild beluga whales (Delphinapterus leucas)
during a collection-and-release experiment in Bristol Bay, AK, USA. Here we summarize the
methods and initial data from one animal, discussing the implications of this experiment.
Audiograms were collected from 4-150 kHz. The animal with the lowest threshold heard best
at 80 kHz and demonstrated overall good hearing from 22-110 kHz. The robustness of the
methodology and data suggest AEP audiograms can be incorporated into future collection-and-release health assessments. Such methods may provide high-quality results for multiple
animals facilitating population-level audiograms and hearing measures in new species.Project funding and field support provided by Georgia Aquarium and the National Marine
Mammal Laboratory of the Alaska Fisheries Science Center (NMML/AFSC). Field work also
supported by National Marine Fisheries Service Alaska Regional Office (NMFS AKR),
WHOI Arctic Research Initiative, WHOI Ocean Life Institute, U.S. Fish and Wildlife
Service, Bristol Bay Native Association, Alaska SeaLife Center, Shedd Aquarium and Mystic
Aquarium. Audiogram analyses were funded by the Office of Naval Research award number
N000141210203 (from Michael Weise)
The Function of the Medieval in Jean-Jacques Rousseauâs Nouvelle HĂ©loĂŻse: A Rereading of the AbĂ©lard and HĂ©loĂŻse Motif
Apolipoprotein C3 Polymorphisms, Cognitive Function and Diabetes in Caribbean Origin Hispanics
Apolipoprotein C3 (APOC3) modulates triglyceride metabolism through inhibition of lipoprotein lipase, but is itself regulated by insulin, so that APOC3 represents a potential mechanism by which glucose metabolism may affect lipid metabolism. Unfavorable lipoprotein profiles and impaired glucose metabolism are linked to cognitive decline, and all three conditions may decrease lifespan. Associations between apolipoprotein C3 (APOC3) gene polymorphisms and impaired lipid and glucose metabolism are well-established, but potential connections between APOC3 polymorphisms, cognitive decline and diabetes deserve further attention.We examined whether APOC3 single nucleotide polymorphisms (SNPs) m482 (rs2854117) and 3u386 (rs5128) were related to cognitive measures, whether the associations between cognitive differences and genotype were related to metabolic differences, and how diabetes status affected these associations. Study subjects were Hispanics of Caribbean origin (n = 991, aged 45-74) living in the Boston metropolitan area.Cognitive and metabolic measures differed substantially by type II diabetes status. In multivariate regression models, APOC3 m482 AA subjects with diabetes exhibited lower executive function (P = 0.009), Stroop color naming score (P = 0.014) and Stroop color-word score (P = 0.022) compared to AG/GG subjects. APOC3 m482 AA subjects with diabetes exhibited significantly higher glucose (P = 0.032) and total cholesterol (P = 0.028) compared to AG/GG subjects. APOC3 3u386 GC/GG subjects with diabetes exhibited significantly higher triglyceride (P = 0.004), total cholesterol (P = 0.003) and glucose (P = 0.016) compared to CC subjects.In summary, we identified significant associations between APOC3 polymorphisms, impaired cognition and metabolic dysregulation in Caribbean Hispanics with diabetes. Further research investigating these relationships in other populations is warranted
In vitro studies and preliminary in vivo evaluation of silicified concentrated collagen hydrogels
Hybrid and nanocomposite silicacollagen materials derived from concentrated collagen hydrogels were evaluated in vitro and in vivo to establish their potentialities for biological dressings. Silicification significantly improved the mechanical and thermal stability of the collagen network within the hybrid systems. Nanocomposites were found to favor the metabolic activity of immobilized human dermal fibroblastswhile decreasing the hydrogel contraction. Cell adhesion experiments suggested that in vitro cell behavior was dictated by mechanical properties and surface structure of the scaffold. First-to-date in vivo implantation of bulk hydrogels in subcutaneous sites of rats was performed over the vascular inflammatory period. These materials were colonized and vascularized without inducing strong inflammatory response. These data raise reasonable hope for the future application of silicacollagen biomaterials as biological dressings.Fil: Desimone, MartĂn Federico. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de QuĂmica y Metabolismo del FĂĄrmaco. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Instituto de QuĂmica y Metabolismo del FĂĄrmaco; ArgentinaFil: HĂ©lary, Christophe. UniversitĂ© Pierre et Marie Curie; FranciaFil: Quignard, Sandrine. UniversitĂ© Pierre et Marie Curie; FranciaFil: Rietveld, Ivo B. Universite de Paris; FranciaFil: Bataille, Clement. UniversitĂ© de Versailles Saint-quentin-en-yvelines.; FranciaFil: Copello, Guillermo Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de QuĂmica y Metabolismo del FĂĄrmaco. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Instituto de QuĂmica y Metabolismo del FĂĄrmaco; ArgentinaFil: Mosser, Gervaise. UniversitĂ© Pierre et Marie Curie; FranciaFil: Giraud Guille, Marie-Madeleine. UniversitĂ© Pierre et Marie Curie; FranciaFil: Livage, Jacques. UniversitĂ© Pierre et Marie Curie; FranciaFil: Meddahi PellĂ©, Anne. UniversitĂ© de Versailles Saint-quentin-en-yvelines.; FranciaFil: Coradin, Thibaud. UniversitĂ© Pierre et Marie Curie; Franci
Adipocyte mesenchymal transition contributes to mammary tumor progression
Obesity is associated with increased cancer incidence and progression. However, the relationship between adiposity and cancer remains poorly understood at the mechanistic level. Here, we report that adipocytes from tumor-invasive mammary fat undergo de-differentiation to fibroblast-like precursor cells during tumor progression and integrate into the tumor microenvironment. Single-cell sequencing reveals that these de-differentiated adipocytes lose their original identities and transform into multiple cell types, including myofibroblast- and macrophage-like cells, with their characteristic features involved in immune response, inflammation, and extracellular matrix remodeling. The de-differentiated cells are metabolically distinct from tumor-associated fibroblasts but exhibit comparable effects on tumor cell proliferation. Inducing de-differentiation by Xbp1s overexpression promotes tumor progression despite lower adiposity. In contrast, promoting lipid-storage capacity in adipocytes through MitoNEET overexpression curbs tumor growth despite greater adiposity. Collectively, the metabolic interplay between tumor cells and adipocytes induces adipocyte mesenchymal transition and contributes to reconfigure the stroma into a more tumor-friendly microenvironment
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