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Sample records for mesures par resonance

  1. Mesure de coefficients d'absorption de plasmas créés par laser nanoseconde

    NASA Astrophysics Data System (ADS)

    Thais, F.; Chenais-Popovics, C.; Eidmann, K.; Bastiani, S.; Blenski, T.; Gilleron, F.

    2005-06-01

    La mesure des coefficients d'absorption dans les plasmas chauds est particulièrement utile dans le domaine de la fusion par confinement inertiel ainsi que dans divers contextes en astrophysique. Le développement des calculs de physique atomique qui y sont associés repose sur des hypothèses qu'il est nécessaire de vérifier dans la plus large gamme possible de conditions physiques. Nous présentons ici la méthode de mesure et d'analyse employée en nous appuyant sur l'exemple des cibles multicouches nickel/aluminium.

  2. Mesure du taux de la capture radiative du muon par l'hydrogene liquide

    NASA Astrophysics Data System (ADS)

    Jonkmans, Guy

    À basse énergie, l'interaction faible entre leptons et quarks est décrite par une interaction de la forme courant × courant de type V - A. La présence de l'interaction forte induit des couplages additionnels qui doivent être déterminés expérimentalement. De ceux-ci, le couplage pseudoscalaire induit, gp , est mesuré avec la plus grande incertitude et fait l'objet de la présente recherche. L'hypothèse du Courant Axial Partiellement Conservé (CAPC) et l'usage de la relation de Goldberger-Treiman relie gp au couplage axial ga . Cette relation a été vérifiée traditionnellement par la Capture Ordinaire du Muon (COM) à une valeur fixe du moment de transfert q. La Capture Radiative du Muon (CRM), m- p-->nnmg , est un meilleur outil pour l'étude de gp à cause de sa dépendance variable en q2 qui offre une plus grande sensibilité dans la partie à haute énergie du spectre des photons. Toutefois, le petit rapport d'embranchement (~10-8) de la CRM par rapport à la désintégration du muon a retardé cette mesure jusqu'à ce jour. La théorie et les difficultés expérimentales associées à la détection des photons de CRM sont présentées au deuxième chapitre. On décrit ensuite, au troisième chapitre, les composantes du système de détection. Ce détecteur est un spectromètre à paires de grand angle solide (~3p) et qui permet l'observation des photons par l'analyse des électrons et des positrons de photo-conversion. Ainsi, le bruit de fond important des neutrons de la COM ne constitue pas un problème pour cette mesure. Nous décrivons, au quatrième chapitre, toutes les étapes de l'analyse, nécessaires pour la réduction des multiples bruits de fond. Le cinquième chapitre présente le calcul des efficacités ainsi que l'estimation des erreurs systématiques. Le sixième chapitre démontre comment l'on extrait le rapport d'embranchement pour la CRM ainsi que la valeur ae gp . On insiste sur la dépendance de gp en fonction de la valeur de

  3. Developpement de mesures non destructives, par ondes ultrasonores, d'epaisseurs de fronts de solidification dans les reacteurs metallurgiques

    NASA Astrophysics Data System (ADS)

    Floquet, Jimmy

    Dans les cuves d'electrolyse d'aluminium, le milieu de reaction tres corrosif attaque les parois de la cuve, ce qui diminue leur duree de vie et augmente les couts de production. Le talus, qui se forme sous l'effet des pertes de chaleur qui maintiennent un equilibre thermique dans la cuve, sert de protection naturelle a la cuve. Son epaisseur doit etre controlee pour maximiser cet effet. Advenant la resorption non voulue de ce talus, les degats generes peuvent s'evaluer a plusieurs centaines de milliers de dollars par cuve. Aussi, l'objectif est de developper une mesure ultrasonore de l'epaisseur du talus, car elle serait non intrusive et non destructive. La precision attendue est de l'ordre du centimetre pour des mesures d'epaisseurs comprenant 2 materiaux, allant de 5 a 20 cm. Cette precision est le facteur cle permettant aux industriels de controler l'epaisseur du talus de maniere efficace (maximiser la protection des parois tout en maximisant l'efficacite energetique du procede), par l'ajout d'un flux thermique. Cependant, l'efficacite d'une mesure ultrasonore dans cet environnement hostile reste a demontrer. Les travaux preliminaires ont permis de selectionner un transducteur ultrasonore a contact ayant la capacite a resister aux conditions de mesure (hautes temperatures, materiaux non caracterises...). Differentes mesures a froid (traite par analyse temps-frequence) ont permis d'evaluer la vitesse de propagation des ondes dans le materiau de la cuve en graphite et de la cryolite, demontrant la possibilite d'extraire l'information pertinente d'epaisseur du talus in fine. Fort de cette phase de caracterisation des materiaux sur la reponse acoustique des materiaux, les travaux a venir ont ete realises sur un modele reduit de la cuve. Le montage experimental, un four evoluant a 1050 °C, instrumente d'une multitude de capteurs thermique, permettra une comparaison de la mesure intrusive LVDT a celle du transducteur, dans des conditions proches de la mesure

  4. Caractérisation expérimentale de la dynamique des roues aubagées de turbomachines par mesures optiques

    NASA Astrophysics Data System (ADS)

    Lombard, J.-P.; Seinturier, E.; Raynaud, J.-L.

    2002-12-01

    La conception dynamique des roues aubagées consiste à éviter que les modes de la structure ne soient excités par des harmoniques du régime moteur (coïncidences prédites à partir de l'analyse d'un diagramme de Campbell). En pratique, il est impossible d'éviter toute coïncidence sur l'ensemble de la plage de fonctionnement. Un essai moteur est effectué à la fin du cycle de conception pour déterminer les niveaux vibratoires. A partir de cet essai et du modèle EF validé, le concepteur vérifie ses marges fréquentielles et sait déterminer si la roue aubagée est soumise ou non au risque de fatigue vibratoire (HCF). Cette analyse nécessite plusieurs calculs EF dont les modèles ont été recalés par rapport à des essais partiels de distribution de contrainte (mesurée à l'aide de jauges de déformation). Une des limitations de ce type de mesure réside dans le caractère intrusif de l'instrumentation qui perturbe le comportement dynamique des aubes, notamment pour les modes de rang élevé. L'application de mesures optiques non intrusives sur des aubes est présentée ici, et met en évidence la précision qu'il est possible d'obtenir sur la mesure des déformées modales. De plus, ce papier illustre l'intérêt de borner la précision des mesures obtenues par exemple dans la caractérisation des dispersions en fréquence aube à aube, dispersions qui se traduisent par une amplification de la réponse aéroélastique de la structure.

  5. Etude du mecanisme de predissociation de l'ion moleculaire de protoxyde d'azote par la mesure de l'energie cinetique des fragments de l'oxyde nitrique et de l'oxygene

    NASA Astrophysics Data System (ADS)

    Delisle, Claude

    La reaction N2 + O+ ↔ NO + + N, laquelle joue un role important dans la physique de la haute atmosphere, a ete le sujet de plusieurs etudes. Bien que cette reaction ait ete l'objet d'une quantite importante de travaux, ces derniers ne permettent toutefois pas de comprendre entierement le mecanisme d'un point de vue quantique, particulierement les niveaux d'energie excites des fragments qui permettent cette reaction. Puisque cette reaction n'est pas tres facile a reproduire en laboratoire, nous avons utilise la spectroscopie laser sur faisceaux d'ions rapides afin d'explorer les limites de dissociation de l'ion moleculaire intermediaire de cette reaction, a savoir l'ion N2O+. Le faisceau d'ions N2O+ rapides, apres excitation de l'ion moleculaire vers un niveau predissocie de l'etat A2Sigma+, se dissocie pour produire les fragments ioniques O+ et NO+. Par la mesure de la variation du nombre de fragments ioniques en fonction de l'energie cinetique des ions N2O+, nous avons enregistre les spectres de predissociation de l'ion N2O+. Lorsque c'etait possible, nous avons procede a l'analyse de ces spectres de dissociation afin d'en tirer les constantes moleculaires. Pour certaines des transitions rotationnelles intenses, nous avons mesure l'energie cinetique acquise par les fragments lors de la predissociation de l'ion N 2O+. Afin d'analyser les distributions en energie cinetique, nous avons developpe une simulation de l'experience en considerant, entre autres choses, la position des niveaux de vibration et de rotation des fragments diatomiques de chacune des limites de dissociation de N2O+. Les resultats de l'analyse sont exprimes en termes de population des niveaux de vibration des fragments diatomiques pour une distribution donnee de la population des niveaux de rotation des fragments. Les resultats ainsi obtenus, montrent que les fragments diatomiques sont produits dans des niveaux de vibration fortement excites. De tels niveaux d'excitation ne correspondent pas aux

  6. Nanoparticules d'or: De l'imagerie par resonance magnetique a la radiosensibilisation

    NASA Astrophysics Data System (ADS)

    Hebert, Etienne M.

    Cette thèse approfondit l'étude de nanoparticules d'or de 5 nm de diamètre recouvertes de diamideéthanethioldiethylènetriaminepentacétate de gadolinium (DTDTPA:Gd), un agent de contraste pour l'imagerie par résonance magnétique (IRM). En guise de ciblage passif, la taille des nanoparticules a été contrôlée afin d'utiliser le réseau de néovaisseaux poreux et perméable des tumeurs. De plus les tumeurs ont un drainage lymphatique déficient qui permet aux nanoparticules de demeurer plus longtemps dans le milieu interstitiel de la tumeur. Les expériences ont été effectuées sur des souris Balb/c femelles portant des tumeurs MC7-L1. La concentration de nanoparticules a pu être mesurée à l'IRM in vivo. La concentration maximale se retrouvait à la fin de l'infusion de 10 min. La concentration s'élevait à 0.3 mM dans la tumeur et de 0.12 mM dans le muscle environnant. Les nanoparticules étaient éliminées avec une demi-vie de 22 min pour les tumeurs et de 20 min pour le muscle environnant. Les nanoparticules ont été fonctionnalisées avec le peptide Tat afin de leur conférer des propriétés de ciblage actif La rétention de ces nanoparticules a ainsi été augmentée de 1600 %, passant d'une demi-vie d'élimination de 22 min à 350 min. La survie des souris a été mesurée à l'aide de courbes Kaplan-Meier et d'un modèle mathématique évalue l'efficacité de traitements. Le modèle nous permet, à l'aide de la vitesse de croissance des tumeurs et de l'efficacité des traitements, de calculer la courbe de survie des spécimens. Un effet antagoniste a été observé au lieu de l'effet synergétique attendu entre une infusion de Au@DTDTPA:Gd et l'irradiation aux rayons X. L'absence d'effet synergétique a été attribuée à l'épaisseur du recouvrement de DTDTPA:Gd qui fait écran aux électrons produits par l'or. De plus, le moyen d'ancrage du recouvrement utilise des thiols qui peuvent s'avérer être des capteurs de radicaux. De plus

  7. MESUR Pathfinder Science Investigations

    NASA Technical Reports Server (NTRS)

    Golombek, M.

    1993-01-01

    The MESUR (Mars Environmental Survey) Pathfinder mission is the first Discovery mission planned for launch in 1996. MESUR Pathfinder is designed as an engineering demonstration of the entry, descent and landing approach to be employed by the follow-on MESUR Network mission, which will land of order 10 small stations on the surface of Mars to investigate interior, atmospheric and surface properties. Pathfinder is a small Mars lander, equipped with a microrover to deploy instruments and explore the local landing site. Instruments selected for Pathfinder include a surface imager on a 1 m pop-up mast (stereo with spectral filters), an atmospheric structure instrument/surface meteorology package, and an alpha proton x-ray spectrometer. The microrover will carry the alpha proton x-ray spectrometer to a number of different rocks and surface materials and provide close-up imaging...

  8. Mapping the topographic epitope landscape on the urokinase plasminogen activator receptor (uPAR) by surface plasmon resonance and X-ray crystallography.

    PubMed

    Zhao, Baoyu; Gandhi, Sonu; Yuan, Cai; Luo, Zhipu; Li, Rui; Gårdsvoll, Henrik; de Lorenzi, Valentina; Sidenius, Nicolai; Huang, Mingdong; Ploug, Michael

    2015-12-01

    The urokinase-type plasminogen activator receptor (uPAR or CD87) is a glycolipid-anchored membrane protein often expressed in the microenvironment of invasive solid cancers and high levels are generally associated with poor patient prognosis (Kriegbaum et al., 2011 [1]). uPAR is organized as a dynamic modular protein structure composed of three homologous Ly6/uPAR domains (LU).This internally flexible protein structure of uPAR enables an allosteric regulation of the interactions with its two principal ligands: the serine protease urokinase-type plasminogen activator (uPA) and the provisional matrix protein vitronectin (Vn) (Mertens et al., 2012; Gårdsvoll et al., 2011; Madsen et al., 2007 [2-4]). The data presented here relates to the non-covalent trapping of one of these biologically relevant uPAR-conformations by a novel class of monoclonal antibodies (Zhao et al., 2015 [5]) and to the general mapping of the topographic epitope landscape on uPAR. The methods required to achieve these data include: (1) recombinant expression and purification of a uPAR-hybrid protein trapped in the desired conformation [patent; WO 2013/020898 A12013]; (2) developing monoclonal antibodies with unique specificities using this protein as antigen; (3) mapping the functional epitope on uPAR for these mAbs by surface plasmon resonance with a complete library of purified single-site uPAR mutants (Zhao et al., 2015; Gårdsvoll et al., 2006 [5,6]); and finally (4) solving the three-dimensional structures for one of these mAbs by X-ray crystallography alone and in complex with uPAR [deposited in the PDB database as 4QTH and 4QTI, respectively]. PMID:26504891

  9. Mesure optimale de tilt et déplacement d'un faisceau gaussien

    NASA Astrophysics Data System (ADS)

    Delaubert, V.; Treps, N.; Fabre, C.; Harb, C.; Lam, P. K.; Bachor, H.

    2006-10-01

    Nous réalisons une expérience de mesure optimale de petits déplacements d'un faisceau gaussien TEM{00}, basée sur une détection homodyne employant un oscillateur local TEM{10}. Nous montrons une amélioration de 56% du signal détecté par rapport à une détection à deux zones. Ce nouveau dispositif permet également de mesurer de façon optimale de petites valeurs de tilt, la quantité conjuguée du déplacement. Enfin, nous montrons que la compression du mode TEM{10} du faisceau incident permet une mesure de déplacement au delà de la limite quantique standard.

  10. Mesure et retroaction sur un qubit multi-niveaux en electrodynamique quantique en circuit non lineair

    NASA Astrophysics Data System (ADS)

    Boissonneault, Maxime

    L'electrodynamique quantique en circuit est une architecture prometteuse pour le calcul quantique ainsi que pour etudier l'optique quantique. Dans cette architecture, on couple un ou plusieurs qubits supraconducteurs jouant le role d'atomes a un ou plusieurs resonateurs jouant le role de cavites optiques. Dans cette these, j'etudie l'interaction entre un seul qubit supraconducteur et un seul resonateur, en permettant cependant au qubit d'avoir plus de deux niveaux et au resonateur d'avoir une non-linearite Kerr. Je m'interesse particulierement a la lecture de l'etat du qubit et a son amelioration, a la retroaction du processus de mesure sur le qubit de meme qu'a l'etude des proprietes quantiques du resonateur a l'aide du qubit. J'utilise pour ce faire un modele analytique reduit que je developpe a partir de la description complete du systeme en utilisant principalement des transfprmations unitaires et une elimination adiabatique. J'utilise aussi une librairie de calcul numerique maison permettant de simuler efficacement l'evolution du systeme complet. Je compare les predictions du modele analytique reduit et les resultats de simulations numeriques a des resultats experimentaux obtenus par l'equipe de quantronique du CEASaclay. Ces resultats sont ceux d'une spectroscopie d'un qubit supraconducteur couple a un resonateur non lineaire excite. Dans un regime de faible puissance de spectroscopie le modele reduit predit correctement la position et la largeur de la raie. La position de la raie subit les decalages de Lamb et de Stark, et sa largeur est dominee par un dephasage induit par le processus de mesure. Je montre que, pour les parametres typiques de l'electrodynamique quantique en circuit, un accord quantitatif requiert un modele en reponse non lineaire du champ intra-resonateur, tel que celui developpe. Dans un regime de forte puissance de spectroscopie, des bandes laterales apparaissent et sont causees par les fluctuations quantiques du champ electromagnetique

  11. Réduction de bruit quantique spatiale et mesures de petits déplacements en optique

    NASA Astrophysics Data System (ADS)

    Treps, N.; Maître, A.; Fabre, C.; Andersen, U.; Buchler, B.; Lame, P. K.; Bachor, H. A.

    2002-06-01

    L'étude des images optiques au niveau quantique nécessite de prendre en compte la structure multimode transverse de la lumière. Dans le cas particulier d'une mesure de position d'un faisceau lumineux effectuée par un détecteur à deux zone, on montre qu'il est nécessaire, si on veut améliorer la précision des mesures en réduisant le bruit quantique de la lumière, d'utiliser deux modes transverses. Nous présentons la première réalisation expérimentale d'une réduction de bruit spatiale, ce qui nous permet ensuite d'effectuer des mesures de petits déplacements sous la limite quantique standard.

  12. Etude des parametres physiques en vue d'applications medicales de l'actionnement magnetique de dispositifs medicaux par un systeme d'imagerie par resonance magnetique

    NASA Astrophysics Data System (ADS)

    Mathieu, Jean-Baptiste

    An actuation and control method for medical devices based on the magnetic gradient coils of a Magnetic Resonance Imaging (MRI) was proposed for the first time in 2002 by NanoRobotics Laboratory [1]. The work undertaken in the present thesis began in the context of demonstrating the concept of automatic navigation of a magnetic bead in vivo. From the point of view of actuation, models and experimental data correlate. A maximum velocity of 13cm/s was measured for a 1.5mm diameter chrome steel bead in the carotid artery of a living swine. The bead was under the influence of magnetic gradients applied by a clinical MRI system without any hardware modification. In light of these results, the aim of this thesis is the study of the physical parameters involved in the development of a first medical application: the steering of magnetic particles in MRI in the context of drug targeting. It was demonstrated that an MRI system equipped with a set of magnetic gradient coils with enhanced amplitude was able to apply a high enough actuation force to act upon magnetic microparticles suspended in a liquid. General rules for MRI actuation were identified. First of all, increasing the amplitude of the main magnetic field of the MRI leads to the increase of the actuation force amplitude only until the ferromagnetic body reaches its saturation magnetization. Moreover, soft ferromagnetic bodies appear to be better candidates for MRI based magnetic actuation because they can reach high saturation magnetizations. Magnetic gradient amplitude appears as a foremost factor to increase the amplitude of the magnetic force. Clinical MRI systems do not provide gradients with high enough amplitude for the applications studied here. Theoretical models developed in this thesis predict that a one order of magnitude increase in gradient amplitude would be required. Implementing actuation dedicated gradient coils is therefore suggested. Finally, a larger ferromagnetic body will lead to higher

  13. La pelade par plaques

    PubMed Central

    Spano, Frank; Donovan, Jeff C.

    2015-01-01

    Résumé Objectif Présenter aux médecins de famille des renseignements de base pour faire comprendre l’épidémiologie, la pathogenèse, l’histologie et l’approche clinique au diagnostic de la pelade par plaques. Sources des données Une recension a été effectuée dans PubMed pour trouver des articles pertinents concernant la pathogenèse, le diagnostic et le pronostic de la pelade par plaques. Message principal La pelade par plaques est une forme de perte pileuse auto-immune dont la prévalence durant une vie est d’environ 2 %. Des antécédents personnels ou familiaux de troubles auto-immuns concomitants, comme le vitiligo ou une maladie de la thyroïde, peuvent être observés dans un petit sous-groupe de patients. Le diagnostic peut souvent être posé de manière clinique en se fondant sur la perte de cheveux non cicatricielle et circulaire caractéristique, accompagnée de cheveux en « point d’exclamation » en périphérie chez ceux dont le problème en est aux premiers stades. Le diagnostic des cas plus complexes ou des présentations inhabituelles peut être facilité par une biopsie et un examen histologique. Le pronostic varie largement et de mauvais résultats sont associés à une apparition à un âge précoce, une perte importante, la variante ophiasis, des changements aux ongles, des antécédents familiaux ou des troubles auto-immuns concomitants. Conclusion La pelade par plaques est une forme auto-immune de perte de cheveux périodiquement observée en soins primaires. Les médecins de famille sont bien placés pour identifier la pelade par plaques, déterminer la gravité de la maladie et poser le diagnostic différentiel approprié. De plus, ils sont en mesure de renseigner leurs patients à propos de l’évolution clinique de la maladie ainsi que du pronostic général selon le sous-type de patients.

  14. Modelisation des vibrations asynchrones d'aubes de compresseurs axiaux par la resonance de l'ecoulement de jeu

    NASA Astrophysics Data System (ADS)

    Thomassin, Jean

    The first step of the research consists of demonstrating the coupling mechanism causing the resonance of an impinging jet on a flexible plate. This demonstration, in essence, aims at verifying the first research hypothesis by demonstrating the resonance of an impinging jet at stream velocities where the resonance has never been observed before when the jet impinges on a flexible plate in vibration rather than on a rigid plate. The chosen approach is experimental. It consists of characterizing the unsteady pressure response of a jet impinging on a flexible plate, whose vibration is induced by a mechanical shaker. The following step of the research consists of verifying the second hypothesis which stipulates that the resonance of the tip clearance flow, based on the same coupling mechanism as the resonant jet-on-flexible-plate, is the fundamental fluid-structure phenomenon behind asynchronous vibrations. The demonstration method is also experimental, though more complex since it involves high-speed rotation of the geometries and instrumentation. The rotor under study is installed in a test-section which isolates the effect of the tip clearance on the blades. Sensitivity studies are conducted with respect to the tip clearance, the blade aerodynamic loading, the inlet temperature and the compressor rotating speed. The results support the second research hypothesis and the critical asynchronous vibration conditions of occurrence are predicted from the proposed coupling mechanism. Until this point, the resonances were predicted by an empirical model of a planar feedback wave travelling upstream towards the separation edge. The coupling mechanism between the mixing layer and the acoustic feedback was assumed to occur when a crest of the sound wave reached the separation edge. This assumption was based on a number of historic empirical observations on oscillating shear layers. The final part of the research aims at analytically capturing the coupling mechanism of a mixing

  15. Anisotropie magnetique du La2NiMnO6 multiferroique par magnetometrie statique et spectroscopie de resonance ferromagnetique

    NASA Astrophysics Data System (ADS)

    Chagnon, Dany

    In this research, magnetic properties of thin films composed of both double- (La2NiMnO6 or LNMOo) and simple-perovskites (LaNi0.5Mn0.5O3 ou LNMOd) are studied. This mixt phase (LNMOm) possesses two magnetic transitions; one for each phase present. It has previously been shown that this phase possesses a higher Curie temperature than LNMOo, approaching room temperature. This property makes room temperature ferromagnetic resonance measurements possible. Angular FMR measurement has already been achieved, but the magnetic anisotropy resulting isn’t completely understood. The goal of this study is to increase our understanding of this anisotropy to get new informations on the structure of the samples. To achieve this goal, thin films of LNMOm have been deposited by PLD on three different substrates; LSAT(001), LSAT(011) and LSAT(111). LSAT has been chosen for his insulating properties limiting the losses in the microwave cavities used for FMR measurements and for his very smooth surface. One sample of LNMOm on LAO(001) was also fabricated by Mangala Singh from the laboratoire des matériaux quantiques during a summer internship of the author. Some of the results obtained on this sample were used in this work. The samples were first characterized using static magnetometry. All samples possess two magnetic transitions, one at low temperature corresponding to the disordered phase and one at high temperature corresponding to the ordered phase. The temperature of these transitions were obtained with precision using the inflection point method. The high temperature transition was then confirmed using magnetocaloric effect, which gave the exact same values. The transition temperature of the ordered phase of all samples was between 268 and 271 K, while the transition of the disordered phase was between 60 and 110 K. A third transition at really low temperature was observed on some samples. The volume and volumic fraction of the ordered and disordered phases were approximated

  16. Capteurs monopodes pour mesures accélérométriques

    NASA Astrophysics Data System (ADS)

    Delaite, R.; Valentin, J.-P.

    1993-08-01

    A new design for accelerometric measurements sensors is described. It uses a plate vibrating in thickness shear mode, maintained by the means of a single holder located at the crystal edge. This mounting does cancel the mechanical and thermal stresses which generally modify the sensor output signal. So the ratio signal/noise of a thickness shear accelerometer is improved and the intrinsic sensitivity is multiplied by a factor 40, by comparison with the sensitivity of a thickness shear plate bonded by the means of two opposite holders. Un nouveau dispositif destiné aux mesures d'accélération est présenté. Il met en œuvre une lame vibrant en cisaillement d'épaisseur, fixée à sa structure de maintien par l'intermédiaire d'une unique liaison. Ce montage permet d'éliminer les contraintes mécaniques et thermiques qui perturbent habituellement le signal de mesure, et qui sont liées soit au montage des éléments du capteur, soit aux variations rapides de température qui interviennent lors de la mise en fonctionnement du capteur. Le rapport signal/bruit d'un accéléromètre à lame vibrant en cisaillement d'épaisseur s'en trouve amélioré et la sensibilité à l'accélération est multipliée par un facteur 40, comparée à celle d'un capteur qui serait constitué d'une lame vibrant en cisaillement d'épaisseur, fixée par deux liaisons diamétralement opposées.

  17. Perrotin et la meilleure mesure française de la vitesse de la lumière

    NASA Astrophysics Data System (ADS)

    Bogaert, G.; Blanc, W.

    2012-12-01

    à la fin du 19ème siècle, la détermination de la vitesse de la lumière a fait l'objet d'une controverse scientifique impliquant d'éminents scientifiques français et américains : Alfred Cornu et Hippolyte Fizeau, d'un côté, Simon Newcomb et Albert Michelson de l'autre. Cette controverse prendra fin de façon inattendue avec les deux mesures réalisées en 1898 et 1902 par Henri Perrotin, le directeur de l'Observatoire de Nice.

  18. MESUR probe aerobrake preliminary design study

    NASA Technical Reports Server (NTRS)

    Tauber, M.; Henline, W.; Chargin, M.; Papadopoulos, P.; Chen, Y.; Yang, L.; Hamm, K.

    1992-01-01

    Aerobrake design for the Mars Environmental Survey (MESUR) vehicles is considered which is intended for both a nominal entry velocity of 7 km/sec and a high-speed case of 9 km/sec. Topics discussed include the entry environment, the thermal protection requirements for several types of heat shield materials, the structural design of the aeroshell, and the total aerobrake masses and mass fractions. For the nominal 7 km/sec entry, a silicone elastometric charring ablator, SLA-561, was found to be the lightest heat shield material. For the 7 km/sec entry, the mass fraction of the aerobrake was 13.2 percent. For the 9 km/sec entry, the heat shield consisted of the medium-density ablator AVCOAT-5026; SLA-561 was used on part of the conical skirt. The aerobrake mass fraction in this case was 18 percent. It is recommended that separate aerobrakes be designed for probes entering at 7 and 9 km/sec.

  19. MESUR probe aerobrake preliminary design study

    NASA Astrophysics Data System (ADS)

    Tauber, M.; Henline, W.; Chargin, M.; Papadopoulos, P.; Chen, Y.; Yang, L.; Hamm, K.

    1992-07-01

    Aerobrake design for the Mars Environmental Survey (MESUR) vehicles is considered which is intended for both a nominal entry velocity of 7 km/sec and a high-speed case of 9 km/sec. Topics discussed include the entry environment, the thermal protection requirements for several types of heat shield materials, the structural design of the aeroshell, and the total aerobrake masses and mass fractions. For the nominal 7 km/sec entry, a silicone elastometric charring ablator, SLA-561, was found to be the lightest heat shield material. For the 7 km/sec entry, the mass fraction of the aerobrake was 13.2 percent. For the 9 km/sec entry, the heat shield consisted of the medium-density ablator AVCOAT-5026; SLA-561 was used on part of the conical skirt. The aerobrake mass fraction in this case was 18 percent. It is recommended that separate aerobrakes be designed for probes entering at 7 and 9 km/sec.

  20. Pars triangularis asymmetry and language dominance.

    PubMed Central

    Foundas, A L; Leonard, C M; Gilmore, R L; Fennell, E B; Heilman, K M

    1996-01-01

    The pars triangular is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization. Images Fig. 1 PMID:8570622

  1. Démonstration expérimentale d'une distribution quantique de clé par codage temporel

    NASA Astrophysics Data System (ADS)

    Boucher, W.; Debuisschert, T.

    2006-10-01

    Nous avons démontré expérimentalement la transmission quantique de clé par codage temporel. Alice envoie des impulsions cohérentes atténuées. La clé est codée dans l'instant de détection des photons chez Bob. Une mesure de la durée de cohérence par moyen interférométrique permet d'assurer un fonctionnement en régime quantique. Nous avons mesuré un taux d'erreur quantique de 3.3% et une chute relative de contraste de l'interféromètre de 8.4%. Ces valeurs permettent d'évaluer un avantage d'information de 0.49 bit/impulsion pour Alice et Bob par rapport à un espion éventuel.

  2. Resonance

    NASA Astrophysics Data System (ADS)

    Perozzi, E.; Murdin, P.

    2000-11-01

    A resonance in CELESTIAL MECHANICS occurs when some of the quantities characterizing the motion of two or more celestial bodies can be considered as commensurable, i.e. their ratio is close to an integer fraction. In a simplified form, this can be expressed as ...

  3. Par-4: A New Activator of Myosin Phosphatase

    PubMed Central

    Vetterkind, Susanne; Lee, Eunhee; Sundberg, Eric; Poythress, Ransom H.; Tao, Terence C.; Preuss, Ute

    2010-01-01

    Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response (Par)-4 modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4 and reduced by Par-4 phosphorylation. Overexpression of Par-4 leads to increased phosphatase activity of immunoprecipitated MP, whereas small interfering RNA knockdown of endogenous Par-4 significantly decreases MP activity and increases MYPT1 phosphorylation. LC20 phosphorylation assays demonstrate that overexpression of Par-4 reduces LC20 phosphorylation. In contrast, a phosphorylation site mutant, but not wild-type Par-4, interferes with zipper-interacting protein kinase (ZIPK)-mediated MP inhibition. We conclude from our results Par-4 operates through a “padlock” model in which binding of Par-4 to MYPT1 activates MP by blocking access to the inhibitory phosphorylation sites, and inhibitory phosphorylation of MYPT1 by ZIPK requires “unlocking” of Par-4 by phosphorylation and displacement of Par-4 from the MP complex. PMID:20130087

  4. Mars Environmental Survey (MESUR): Science objectives and mission description

    NASA Technical Reports Server (NTRS)

    Hubbard, G. Scott; Wercinski, Paul F.; Sarver, George L.; Hanel, Robert P.; Ramos, Ruben

    1992-01-01

    In-situ observations and measurements of Mars are objectives of a feasibility study beginning at the Ames Research Center for a mission called the Mars Environmental SURvey (MESUR). The purpose of the MESUR mission is to emplace a pole-to-pole global distribution of landers on the Martian surface to make both short- and long-term observations of the atmosphere and surface. The basic concept is to deploy probes which would directly enter the Mars atmosphere, provide measurements of the upper atmospheric structure, image the local terrain before landing, and survive landing to perform meteorology, seismology, surface imaging, and soil chemistry measurements. MESUR is intended to be a relatively low-cost mission to advance both Mars science and human presence objectives. Mission philosophy is to: (1) 'grow' a network over a period of years using a series of launch opportunities, thereby minimizing the peak annual costs; (2) develop a level-of-effort which is flexible and responsive to a broad set of objectives; (3) focus on science while providing a solid basis for human exploration; and (4) minimize project cost and complexity wherever possible. In order to meet the diverse scientific objectives, each MESUR lander will carry the following strawman instrument payload consisting of: (1) Atmospheric structure experiment, (2) Descent and surface imagers, (3) Meteorology package, (4) Elemental composition instrument, (5) 3-axis seismometer, and (6) Thermal analyzer/evolved gas analyzer. The feasibility study is primarily to show a practical way to design an early capability for characterizing Mars' surface and atmospheric environment on a global scale. The goals are to answer some of the most urgent questions to advance significantly our scientific knowledge about Mars, and for planning eventual exploration of the planet by robots and humans.

  5. Mesure de haute resolution de la fonction de distribution radiale du silicium amorphe pur

    NASA Astrophysics Data System (ADS)

    Laaziri, Khalid

    1999-11-01

    Cette these porte sur l'etude de la structure du silicium amorphe prepare par irradiation ionique. Elle presente des mesures de diffraction de rayons X sur de la poudre de silicium cristallin, du silicium amorphe relaxe et non relaxe, ainsi que tous les developpements mathematiques et physiques necessaires pour extraire la fonction de distribution radiale correspondant a chaque echantillon. Au Chapitre I, nous presentons une methode de fabrication de membranes minces de silicium amorphe pur. Il y a deux etapes majeures lors du processus de fabrication: l'implantation ionique, afin de creer une couche amorphe de plusieurs microns et l'attaque chimique, pour enlever le reste du materiau cristallin. Nous avons caracterise premierement les membranes de silicium amorphe par spectroscopie Raman pour verifier qu'il ne reste plus de trace de materiau cristallin dans les films amorphes. Une deuxieme caracterisation par detection de recul elastique (ERD-TOF) sur ces memes membranes a montre qu'il y a moins de 0.1% atomique de contaminants tels que l'oxygene, le carbone, et l'hydrogene. Au Chapitre II, nous proposons une nouvelle methode de correction de la contribution inelastique "Compton" des spectres de diffusion totale afin d'extraire les pics de diffusion elastique, responsable de la diffraction de Bragg. L'article presente tout d'abord une description simplifiee d'une theorie sur la diffusion inelastique dite "Impulse Approximation" (IA) qui permet de calculer des profils de Compton en fonction de l'energie et de l'angle de diffusion 2theta. Ces profils sont utilises comme fonction de lissage de la diffusion Compton experimentale. Pour lisser les pics de diffusion elastique, nous avons utilise une fonction pic de nature asymetrique. Aux Chapitre III, nous exposons de maniere detaillee les resultats des experiences de diffraction de rayons X sur les membranes de silicium amorphe et la poudre de silicium cristallin que nous avons preparees. Nous abordons aussi les

  6. Relation entre les caractéristiques des table-bancs et les mesures anthropométriques des écoliers au Benin

    PubMed Central

    Falola, Stève Marjelin; Gouthon, Polycarpe; Falola, Jean-Marie; Fiogbe, Michel Armand; Nigan, Issiako Bio

    2014-01-01

    Introduction Le mobilier scolaire et la posture assise en classe sont souvent impliqués dans l'apparition des douleurs rachidiennes, influant de fait sur la qualité des tâches réalisées par les apprenants. Aucune étude n'a encore vérifié le degré d'adéquation entre les caractéristiques du mobilier et celles des écoliers au Bénin. L'objectif de cette étude transversale est donc de déterminer la relation entre les dimensions des table-bancs utilisées en classe et les mesures anthropométriques des écoliers au Bénin. Methods Elle a été réalisée avec un échantillon probabiliste de 678 écoliers, âgés de 4 à 17 ans. Les mesures anthropométriques des écoliers et les mensurations relatives aux longueurs, largeurs et hauteurs des table-bancs ont été mesurées, puis intégrées aux équations proposées dans la littérature. Les pourcentages des valeurs situées hors des limitesacceptables, dérivées de l'application des équations ont été calculés. Results La largeur et la hauteur des table-bancs utilisées par les écoliers étaient plus élevées (p < 0,05) que les valeurs de référence recommandées par les structures officielles de contrôle et de production des mobiliers scolaires au Bénin. Quel que soit le sexe, il y avait une inadéquation entre la largeur du banc et la longueur fesse-poplité, puis entre la hauteur de la table et la distance coude-bancdes écoliers. Conclusion Les résultats suggèrent de prendre en compte l’évolution des mesures anthropométriques des écoliers dans la confection des table-bancs, afin de promouvoir de bonnes postures assises en classe et de réduire le risque de troubles du rachis. PMID:25317232

  7. Calcul numérique accéléré de mesures de performance sur les modèles Markoviens appliqués aux systèmes informatiques et de télécommunications

    NASA Astrophysics Data System (ADS)

    Ghaddar, A.; Sinno, N.

    2005-05-01

    La complexité du phénomène de files d'attente dans les systèmes informatiques et télécommunications nécessite leur simulation par des modèles Markoviens pour les mesures de performance, mesure des délais d'attente au niveau des routeurs pour le modèle informatique et l'étude de la gestion des appels téléphoniques pour le modèle des circuits téléphoniques. L'optimisation des méthodes numériques de résolution des équations relatives à ces deux modèles va permettre d' ídentifier les critères de convergence rapide vers les états stationnaires correspondant à ces mesures.

  8. Pars Injuries in Athletes.

    PubMed

    Oren, Jonathan H; Gallina, Jason M

    2016-03-01

    Pars injuries are common causes of low back pain in adolescent athletes. Workup traditionally has included lumbar radiographs with oblique views and single-photon emission computed tomography (SPECT). However, recent literature has demonstrated the accuracy of MRI as a diagnostic modality. Acute injuries may be amenable to bracing with the goal of a healed lesion. Most cases of spondylolysis will result in asymptomatic non-union, though pars repair is an option for symptomatic pars defects without spondylolisthesis. PMID:26977552

  9. Application of RTG (SiGe) technology to MESUR

    SciTech Connect

    Vicente, F.A. )

    1993-01-15

    This paper discusses providing electrical power for the Mars Environmental Survey (MESUR) mission. The use of radioisotope thermoelectric generator (RTG) technology using SiGe enables total satisfaction of the mission requirements. This technology permits placing the survey landers at any location on Mars, with the capability of transmitting data directly to Earth. If a relay satellite is deployed, the modular construction of the RTG permits tailoring the power to match that mission configuration. Presented are various configurations and trades directed toward achieving operational status, first with a pathfinder'' mission and subsequently with the full complement of landers.

  10. Application of RTG (SiGe) technology to MESUR

    NASA Astrophysics Data System (ADS)

    Vicente, Francis A.

    1993-01-01

    This paper discusses providing electrical power for the Mars Environmental Survey (MESUR) mission. The use of radioisotope thermoelectric generator (RTG) technology using SiGe enables total satisfaction of the mission requirements. This technology permits placing the survey landers at any location on Mars, with the capability of transmitting data directly to Earth. If a relay satellite is deployed, the modular construction of the RTG permits tailoring the power to match that mission configuration. Presented are various configurations and trades directed toward achieving operational status, first with a ``pathfinder'' mission and subsequently with the full complement of landers.

  11. Nonconsecutive Pars Interarticularis Defects.

    PubMed

    Elgafy, Hossein; Hart, Ryan C; Tanios, Mina

    2015-12-01

    Lumbar spondylolysis is a well-recognized condition occurring in adolescents because of repetitive overuse in sports. Nonconsecutive spondylolysis involving the lumbar spine is rare. In contrast to single-level pars defects that respond well to conservative treatment, there is no consensus about the management of multiple-level pars fractures; a few reports indicated that conservative management is successful, and the majority acknowledged that surgery is often required. The current study presents a rare case of pars fracture involving nonconsecutive segments and discusses the management options. In this case report, we review the patient's history, clinical examination, radiologic findings, and management, as well as the relevant literature. An 18-year-old man presented to the clinic with worsening lower back pain related to nonconsecutive pars fractures at L2 and L5. After 6 months of conservative management, diagnostic computed tomography-guided pars block was used to localize the symptomatic level at L2, which was treated surgically; the L5 asymptomatic pars fracture did not require surgery. At the last follow-up 2 years after surgery, the patient was playing baseball and basketball, and denied any back pain. This article reports a case of rare nonconsecutive pars fractures. Conservative management for at least 6 months is recommended. Successful management depends on the choice of appropriate treatment for each level. Single-photon emission computed tomography scan, and computed tomography-guided pars block are valuable preoperative tools to identify the symptomatic level in such a case. PMID:26665257

  12. MESUR: USAGE-BASED METRICS OF SCHOLARLY IMPACT

    SciTech Connect

    BOLLEN, JOHAN; RODRIGUEZ, MARKO A.; VAN DE SOMPEL, HERBERT

    2007-01-30

    The evaluation of scholarly communication items is now largely a matter of expert opinion or metrics derived from citation data. Both approaches can fail to take into account the myriad of factors that shape scholarly impact. Usage data has emerged as a promising complement to existing methods o fassessment but the formal groundwork to reliably and validly apply usage-based metrics of schlolarly impact is lacking. The Andrew W. Mellon Foundation funded MESUR project constitutes a systematic effort to define, validate and cross-validate a range of usage-based metrics of schlolarly impact by creating a semantic model of the scholarly communication process. The constructed model will serve as the basis of a creating a large-scale semantic network that seamlessly relates citation, bibliographic and usage data from a variety of sources. A subsequent program that uses the established semantic network as a reference data set will determine the characteristics and semantics of a variety of usage-based metrics of schlolarly impact. This paper outlines the architecture and methodology adopted by the MESUR project and its future direction.

  13. Planetary surface exploration: MESUR/autonomous lunar rover

    NASA Technical Reports Server (NTRS)

    Stauffer, Larry; Dilorenzo, Matt; Austin, Dave; Ayers, Raymond; Burton, David; Gaylord, Joe; Kennedy, Jim; Lentz, Dale; Laux, Richard; Nance, Preston

    1992-01-01

    Planetary surface exploration micro-rovers for collecting data about the Moon and Mars was designed by the Department of Mechanical Engineering at the University of Idaho. The goal of both projects was to design a rover concept that best satisfied the project objectives for NASA-Ames. A second goal was to facilitate student learning about the process of design. The first micro-rover is a deployment mechanism for the Mars Environmental SURvey (MESUR) Alpha Particle/Proton/X-ray instruments (APX). The system is to be launched with the sixteen MESUR landers around the turn of the century. A Tubular Deployment System and a spiked-legged walker was developed to deploy the APX from the lander to the Martian surface. While on Mars the walker is designed to take the APX to rocks to obtain elemental composition data of the surface. The second micro-rover is an autonomous, roving vehicle to transport a sensor package over the surface of the moon. The vehicle must negotiate the lunar-terrain for a minimum of one year by surviving impacts and withstanding the environmental extremes. The rover is a reliable track-driven unit that operates regardless of orientation which NASA can use for future lunar exploratory missions. A detailed description of the designs, methods, and procedures which the University of Idaho design teams followed to arrive at the final designs are included.

  14. Planetary surface exploration MESUR/autonomous lunar rover

    NASA Technical Reports Server (NTRS)

    Stauffer, Larry; Dilorenzo, Matt; Austin, Dave; Ayers, Raymond; Burton, David; Gaylord, Joe; Kennedy, Jim; Laux, Richard; Lentz, Dale; Nance, Preston

    1992-01-01

    Planetary surface exploration micro-rovers for collecting data about the Moon and Mars have been designed by the Department of Mechanical Engineering at the University of Idaho. The goal of both projects was to design a rover concept that best satisfied the project objectives for NASA/Ames. A second goal was to facilitate student learning about the process of design. The first micro-rover is a deployment mechanism for the Mars Environmental Survey (MESUR) Alpha Particle/Proton/X-ray (APX) Instrument. The system is to be launched with the 16 MESUR landers around the turn of the century. A Tubular Deployment System and a spiked-legged walker have been developed to deploy the APX from the lander to the Martian Surface. While on Mars, the walker is designed to take the APX to rocks to obtain elemental composition data of the surface. The second micro-rover is an autonomous, roving vehicle to transport a sensor package over the surface of the moon. The vehicle must negotiate the lunar terrain for a minimum of one year by surviving impacts and withstanding the environmental extremes. The rover is a reliable track-driven unit that operates regardless of orientation that NASA can use for future lunar exploratory missions. This report includes a detailed description of the designs and the methods and procedures which the University of Idaho design teams followed to arrive at the final designs.

  15. Planetary surface exploration MESUR/autonomous lunar rover

    NASA Astrophysics Data System (ADS)

    Stauffer, Larry; Dilorenzo, Matt; Austin, Dave; Ayers, Raymond; Burton, David; Gaylord, Joe; Kennedy, Jim; Laux, Richard; Lentz, Dale; Nance, Preston

    Planetary surface exploration micro-rovers for collecting data about the Moon and Mars have been designed by the Department of Mechanical Engineering at the University of Idaho. The goal of both projects was to design a rover concept that best satisfied the project objectives for NASA/Ames. A second goal was to facilitate student learning about the process of design. The first micro-rover is a deployment mechanism for the Mars Environmental Survey (MESUR) Alpha Particle/Proton/X-ray (APX) Instrument. The system is to be launched with the 16 MESUR landers around the turn of the century. A Tubular Deployment System and a spiked-legged walker have been developed to deploy the APX from the lander to the Martian Surface. While on Mars, the walker is designed to take the APX to rocks to obtain elemental composition data of the surface. The second micro-rover is an autonomous, roving vehicle to transport a sensor package over the surface of the moon. The vehicle must negotiate the lunar terrain for a minimum of one year by surviving impacts and withstanding the environmental extremes. The rover is a reliable track-driven unit that operates regardless of orientation that NASA can use for future lunar exploratory missions. This report includes a detailed description of the designs and the methods and procedures which the University of Idaho design teams followed to arrive at the final designs.

  16. Par Pond water balance

    SciTech Connect

    Hiergesell, R.A.; Dixon, K.L.

    1996-06-01

    A water budget for the Par Pond hydrologic system was established in order to estimate the rate of groundwater influx to Par Pond. This estimate will be used in modeling exercises to predict Par Pond reservoir elevation and spillway discharge in the scenario where Savannah River water is no longer pumped and discharged into Par Pond. The principal of conservation of mass was used to develop the water budget, where water inflow was set equal to water outflow. Components of the water budget were identified, and the flux associated with each was determined. The water budget was considered balanced when inflow and outflow summed to zero. The results of this study suggest that Par Pond gains water from the groundwater system in the upper reaches of the reservoir, but looses water to the groundwater system near the dam. The rate of flux of groundwater from the water table aquifer into Par Pond was determined to be 13 cfs. The rate of flux from Par Pond to the water table aquifer near the dam was determined to be 7 cfs.

  17. uPAR

    PubMed Central

    Uhrin, Pavel; Breuss, Johannes M.

    2013-01-01

    Vascular endothelial growth factor (VEGF)-initiated angiogenesis requires both coordinated proteolytic degradation of extracellular matrix provided by the urokinase plasminogen activator/urokinase receptor (uPA/uPAR) system and regulation of cell-migration provided by integrin–matrix interaction. Previously we have shown that stimulation of pericellular proteolysis induced by VEGF occurs via the VEGF receptor-2 leading to redistribution of uPAR to focal adhesions at the leading edge of endothelial cells. In our recent work published in Cardiovascular Research, we investigated the mechanisms underlying the uPAR-dependent modulation of VEGF-induced endothelial migration. By applying a micropatterning technique we described that VEGF stimulation results in complex formation between uPAR and α5β1-integrin on the cell surface. The subsequent internalization of this complex, important for receptor redistribution, was demonstrated by flow-cytometry and immunohistochemistry. Targeting of the interaction site between uPAR and α5β1 impairs receptor internalization and leads to the inhibition of endothelial cell migration in vitro and in an angiogenesis model in vivo. This proof-of-principle that the interface of uPAR and α5β1-integrin may represent a promising site to therapeutically target tumor angiogenesis raises hope for the development of an anti-angiogenic approach that is limited to only the mobilizing effect of VEGF to endothelial cells, and does not interfere with the inarguably positive effect of VEGF as survival factor. PMID:23076213

  18. ``Astrophysique sur Mesure'', E-learning in Astronomy and Astrophysics

    NASA Astrophysics Data System (ADS)

    Mosser, Benoît; Delsanti, Audrey; Guillaume, Damien; Balança, Christian; Balkowski, Chantal

    2011-06-01

    ``Astrophysique sur Mesure'' (astrophysics made-to-measure) is a set of e-learning programmes started 4 years ago at the Paris Observatory. In order to deliver attractive and efficient programmes, we have added many multimedia tools to usual lectures: animations, Java applets. The programmes are presented on two different platforms. The first one offers the content of all the lectures in free access. A second platform with restricted access is provided to registered students taking part in the e-learning program and benefiting from the help of tutors. The development of these programs helps to increase the sphere of influence of astronomy taught at the Paris Observatory, hence to increase the presence of astronomy in various degree courses. Instead of teaching classical astronomy lectures to a happy few, we can bring astronomy and astrophysics to a wider audience.

  19. Modélisation des charges d'espace dans les isolants solides par une analyse spectrale

    NASA Astrophysics Data System (ADS)

    Haas, V.; Scouarnec, Ch.; Franceschi, J. L.

    1998-01-01

    A mathematical method based on spectral algebra is developped for the thermal modulation method. These methods permit to measure the space charge distribution in solid insulators. The modelling presented permits to evaluate the performances and the limitations of the measurement method. Une linéarisation par l'algèbre spectrale a été développée dans une méthode de modulation thermique pour mesurer la distribution des charges électriques dans les isolants solides. La modélisation présentée permet d'évaluer les performances et les limites tant numériques que physiques de la méthode de mesure.

  20. THE MEASURES PAR PROJECT

    NASA Astrophysics Data System (ADS)

    Frouin, R. J.; Franz, B.

    2009-12-01

    The solar energy available for photosynthesis, known as PAR, controls the growth of phytoplankton and, therefore, regulates the composition and evolution of marine ecosystems. Knowing the spatial and temporal distribution of PAR over the oceans is critical to understanding biogeochemical cycles of carbon, nutrients, and oxygen, and to address important climate and global change issues such as the fate of anthropogenic atmospheric carbon dioxide. In view of this, a 12-year time series of PAR at the ocean surface, starting in September 1997, is being produced by the NASA Ocean Biology Processing Group from SeaWiFS, MODIS-Terra, and MODIS-Aqua data. The product covers the global oceans, with a spatial resolution of about 9.3x9.3 km (equal area grid) and a temporal resolution of one day. PAR is computed as the difference between the 400-700 nm solar flux incident on the top of the atmosphere (known) and reflected back to space by the atmosphere and surface (derived from satellite radiance), taking into account atmospheric absorption (modeled). Knowledge of pixel composition is not required, eliminating the need for cloud screening and arbitrary assumptions about sub-pixel cloudiness. Combining data from satellite sensors with different equatorial crossing times accounts for the diurnal variability of clouds and, therefore, increases accuracy on a daily time scale. The processing system, including routine check of accuracy and control of quality, is designed to operate during the entire lifetime of SeaWiFS and MODIS, and to accommodate future sensors with ocean-color capabilities. Maps of daily, weekly, and monthly PAR obtained from individual sensors are presented, as well as merged products. Accuracy is quantified in comparisons with other satellite estimates, the National Centers for Environmental Prediction reanalysis product, and in-situ measurements from fixed buoys and platforms. The good statistical performance makes the satellite PAR product suitable for large

  1. Traumatismes Oculaires par Petards: Bilan sur Trois Annees

    PubMed Central

    Zouaoui-Kesraoui, N.; Derdour, A.

    2009-01-01

    Summary Les accidents dus aux pétards sont des accidents graves. Leur recrudescence ces dernières années en Algérie, essentiellement durant les fêtes du Mawlid Ennabaoui (fête de la naissance du prophète), mérite à notre sens d'entreprendre des bilans exhaustifs dont celui-ci dans le but d'une sensibilisation de toutes les compétences concernées. Nous avons réuni sur trois années consécutives (2002, 2003, 2004) 60 dossiers de malades ayant subi des accidents oculaires par pétards. Nos patients sont répartis en 42 consultations pour blessures légères et 18 hospitalisations pour blessures graves. Parmi ces derniers, neuf ont présenté des complications et séquelles graves (cinq cas de cécité par atrophie du globe oculaire, trois cas de cécité cornéenne et un cas de cécité par trou maculaire). Dans tous ces cas l'incapacité permanente partielle est au minimum de 30%. Au vu de ces données nous proposons des mesures d'éducation sanitaire et une sensibilisation du grand public aux traumatismes oculaires, par le biais de mé dias appropriés: radio, télévision, affiches. PMID:21991157

  2. Trajectory Based Heating and Ablation Calculations for MESUR Pathfinder Aeroshell

    NASA Technical Reports Server (NTRS)

    Chen, Y. K.; Henline, W. D.; Tauber, M. E.; Arnold, James O. (Technical Monitor)

    1994-01-01

    Based on the geometry of Mars Environment Survey (MESUR) Pathfinder aeroshell and an estimated Mars entry trajectory, two-dimensional axisymmetric time dependent calculations have been obtained using GIANTS (Gauss-Siedel Implicit Aerothermodynamic Navier-Stokes code with Thermochemical Surface Conditions) code and CMA (Charring Material Thermal Response and Ablation) Program for heating analysis and heat shield material sizing. These two codes are interfaced using a loosely coupled technique. The flowfield and convective heat transfer coefficients are computed by the GIANTS code with a species balance condition for an ablating surface, and the time dependent in-depth conduction with surface blowing is simulated by the CMA code with a complete surface energy balance condition. In this study, SLA-561V has been selected as heat shield material. The solutions, including the minimum heat shield thicknesses over aeroshell forebody, pyrolysis gas blowing rates, surface heat fluxes and temperature distributions, flowfield, and in-depth temperature history of SLA-561V, are presented and discussed in detail.

  3. La pelade par plaques

    PubMed Central

    Spano, Frank; Donovan, Jeff C.

    2015-01-01

    Résumé Objectif Présenter aux médecins de famille des renseignements de base pour faire comprendre les schémas thérapeutiques et les résultats des traitements pour la pelade par plaques, de même que les aider à identifier les patients pour qui une demande de consultation en dermatologie pourrait s’imposer. Sources des données Une recension a été effectuée dans PubMed pour trouver des articles pertinents concernant le traitement de la pelade par plaques. Message principal La pelade par plaques est une forme auto-immune de perte pileuse qui touche à la fois les enfants et les adultes. Même s’il n’y a pas de mortalité associée à la maladie, la morbidité découlant des effets psychologiques de la perte des cheveux peut être dévastatrice. Lorsque la pelade par plaques et le sous-type de la maladie sont identifiés, un schéma thérapeutique approprié peut être amorcé pour aider à arrêter la chute des cheveux et possiblement faire commencer la repousse. Les traitements de première intention sont la triamcinolone intralésionnelle avec des corticostéroïdes topiques ou du minoxidil ou les 2. Les médecins de famille peuvent prescrire ces traitements en toute sécurité et amorcer ces thérapies. Les cas plus avancés ou réfractaires pourraient avoir besoin de diphénylcyclopropénone topique ou d’anthraline topique. On peut traiter la perte de cils avec des analogues de la prostaglandine. Les personnes ayant subi une perte de cheveux abondante peuvent recourir à des options de camouflage ou à des prothèses capillaires. Il est important de surveiller les troubles psychiatriques en raison des effets psychologiques profonds de la perte de cheveux. Conclusion Les médecins de famille verront de nombreux patients qui perdent leurs cheveux. La reconnaissance de la pelade par plaques et la compréhension du processus pathologique sous-jacent permettent d’amorcer un schéma thérapeutique approprié. Les cas plus graves ou r

  4. Mesure de la Polarisation des Lambda Produits dans les Collisions Positron-Electron AU Lep a L'aide du Detecteur Opal

    NASA Astrophysics Data System (ADS)

    Vandenplas, Denis

    Le Modele Standard est le cadre theorique general qui, jusqu'a present, a permis l'interpretation de tous les resultats experimentaux en physique des hautes energies. Cette theorie decrit, entre autres, la production d'une paire de particules elementaires, formee d'un quark et d'un antiquark, a partir de la desintegration de l'un des bosons mediateurs de l'interaction faible, le Z^0. Cependant, dans ce cas precis, la transformation subsequente des quarks primaires en particules reelles, un processus appele hadronisation, n'est decrite qu'a l'aide de modeles phenomenologiques. Afin de sonder les mecanismes de l'hadronisation, cette these presente la mesure du transfert du spin d'un quark etrange primaire a une particule appelee Lambda lors des desintegrations hadroniques du Z^0. L'etude a ete realisee dans le cadre de la collaboration OPAL, une des quatre experiences menees au collisionneur LEP, la ou des electrons et des positrons sont acceleres jusqu'a une energie commune, sqrt{s} = {rm E_ {cm}}, voisine de l'energie de production du rm Z^0, M_{Z ^0} egale a 91.3 GeV. La theorie electrofaible precise la direction du spin, c'est-a-dire la polarisation, d'un quark etrange primaire provenant de la desintegration d'un Z ^0. Quant a lui, le modele des quarks etablit que l'orientation du spin d'un Lambda est directement reliee a la polarisation du quark etrange dont il provient. La question est de determiner dans quelle mesure la polarisation du quark primaire est transmise au Lambda a la suite du processus de l'hadronisation, decrit dans le cadre de la ChromoDynamique Quantique. Une estimation, qui tient compte de tous ces differents aspects theoriques, evalue a 30% la polarisation des Lambda dont l'impulsion est superieure a 15 GeV/c. La mesure experimentale de la polarisation repose sur l'identification des Lambda a partir de la reconstitution de la desintegration Lambdato ppi^-. Ce processus, qui se deroule par le biais de l'interaction faible, viole la parite car

  5. Incertitude dans les mesures de courant : un obstacle dans la caractérisation des composants en électronique de puissance

    NASA Astrophysics Data System (ADS)

    Farjah, E.; Barbaroux, J.; Perret, R.

    1993-07-01

    The aim of this paper is to clarify the need for the most accurate current measurement applied to the characterization of the power electronic components. The focus is on the behaviour of the normally used high quality high bandwidth current transformers and other sensors to a fast varying high di/dt test current furnished by a new developed test current generator. In this paper after explaining the new strategy of the test generator, different current transformers are tested and characterized and a detailed comparative experimental study is carried out using a non-inductive shunt as the reference. Finally some general remarks and the necessary precautions and different measurement problems are listed and discussed. Le but de cet article est d'essayer de lever les obstacles rencontrés lors des mesures de courant servant à la caractérisation des composants en électronique de puissance. Nous nous sommes penchés sur les différences entre les réponses de quelques capteurs de haute qualité. Après une brève explication du principe d'un générateur de courant de test spécialement conçu pour cette étude, nous comparons les réponses de plusieurs transformateurs de courant par rapport à un shunt aselfique pris pour référence. Enfin nous abordons les différents aspects concernant les précautions qu'il est nécessaire de prendre pour réaliser ce type de mesure.

  6. Protease-activated receptor (PAR)1, PAR2 and PAR4 expressions in esophageal squamous cell carcinoma

    PubMed Central

    LI, Si-Man; JIANG, Ping; XIANG, Yang; WANG, Wei-Wei; ZHU, Yue-Chun; FENG, Wei-Yang; LI, Shu-De; YU, Guo-Yu

    2014-01-01

    Here, we used reverse transcription-PCR (RT-PCR) and western blot to detect protease-activated receptor (PAR) 1, PAR 2 and PAR 4 expression in cancer tissues and cell lines of esophageal squamous cell carcinoma, and investigated the co-relationship between PAR expression and clinic-pathological data for esophageal cancer. The methylation of PAR4 gene promoter involved in esophageal carcinoma was also analyzed. By comparing the mRNA expressions of normal esophageal tissue and human esophageal epithelial cells (HEEpiC), we found that among the 28 cases of esophageal squamous cell carcinoma, PAR1 (60%) and PAR2 (71%) were elevated in 17 and 20 cases, respectively, and PAR4 (68%) expression was lowered in 19 cases. Whereas, in human esophageal squamous cells (TE-1 and TE-10), PAR1 and PAR2 expression was increased but PAR4 was decreased. Combined with clinical data, the expression of PAR1 in poorly differentiated (P=0.016) and middle and lower parts of the esophagus (P=0.016) was higher; expression of PAR4 in poorly differentiated carcinoma was lower (P=0.049). Regarding TE-1 and TE-10 protein expression, we found that in randomized esophageal carcinoma, PAR1 (P=0.027) and PAR2 (P=0.039) expressions were increased, but lowered for PAR4 (P=0.0001). In HEEpiC, TE-1, TE-10, esophageal and normal esophagus tissue samples (case No. 7), the frequency of methylation at the 19 CpG loci of PAR4 was 35.4%, 95.2%, 83.8%, 62.6% and 48.2%, respectively. Our results indicate that the expression of PAR1 and PAR2 in esophageal squamous cell carcinoma is increased but PAR4 is decreased. Hypermethylation of the promoter of the PAR4 gene may contribute to reduced expression of PAR4 in esophageal squamous cell carcinoma. PMID:25297082

  7. Par Pond vegetation status 1996

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1996-12-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the newly emergent, shoreline aquatic plant communities of Par Pond began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level. These surveys continued in July, September, and late October, 1995, and into the early spring and late summer of 1996. Communities similar to the pre-drawdown, Par Pond aquatic plant communities continue to become re-established. Emergent beds of maidencane, lotus, waterlily, watershield, and Pontederia are extensive and well developed. Measures of percent cover, width of beds, and estimates of area of coverage with satellite data indicate regrowth within two years of from 40 to 60% of levels prior to the draw down. Cattail occurrence continued to increase during the summer of 1996, especially in the former warm arm of Par Pond, but large beds common to Par Pond prior to the draw down still have not formed. Lotus has invaded and occupies many of the areas formerly dominated by cattail beds. To track the continued development of macrophytes in Par Pond, future surveys through the summer and early fall of 1997, along with the evaluation of satellite data to map the extent of the macrophyte beds of Par Pond, are planned.

  8. Providing relay communications support for the Mars Environmental Survey (MESUR) mission

    NASA Technical Reports Server (NTRS)

    Swenson, Byron L.; Friedlander, Alan L.

    1992-01-01

    The purpose of the Mars Environmental Survey (MESUR) mission is to put in place, over several launch opportunities, a constellation of Mars landers to make long-term surface observations of the circulation of the atmosphere and changes in climate, and to record the seismic activity of the planetary crust. Short-term objectives will also be addressed. An orbital communications infrastructure capable of providing regular high-rate data transfer to earth from the landers, which are scattered globally from pole to pole, is key to accomplishing the mission goals. A study is thereby presented of the orbit selection for the orbiter spacecraft, which will provide this support, and the relay communications operation. It is concluded that adequate communications support for the objectives of the MESUR mission can be provided by a single orbiter, provided care is taken in the selection of the size and orientation (i.e., inclination and apse line alignment) of the spacecraft orbit.

  9. Immunopathogenic Background of Pars Planitis.

    PubMed

    Przeździecka-Dołyk, Joanna; Węgrzyn, Agnieszka; Turno-Kręcicka, Anna; Misiuk-Hojło, Marta

    2016-04-01

    Pars planitis is defined as an intermediate uveitis of unknown background of systemic disease with characteristic formations such as vitreous snowballs, snowbanks and changes in peripheral retina. The incidence of pars planitis varies 2.4-15.4 % of the uveitis patients. The pathogenesis of the disease is to be determined in future. Clinical and histopathological findings suggest an autoimmune etiology, most likely as a reaction to endogenous antigen of unknown source, with T cells predominant in both vitreous and pars plana infiltrations. T cells subsets play an important role as a memory-effector peripheral cell. Snowbanks are formed as an effect of post inflammatory glial proliferation of fibrous astrocytes. There is also a genetic predisposition for pars planitis by human leukocyte antigen and several other genes. A coexistence of multiple sclerosis and optic neuritis has been described in numerous studies. Epiretinal membrane, cataract, cystoid macular edema, retinal detachment, retinal vasculitis, neovascularization, vitreous peripheral traction, peripheral hole formation, vitreous hemorrhage, disc edema are common complications observed in pars planitis. There is a need to expand the knowledge of the pathogenic and immunologic background of the pars planitis to create an accurate pharmacological treatment. PMID:26438050

  10. Performance comparison of fiber tips in interferometric displacement mesurements

    SciTech Connect

    Moro, Erik; Grahn, Rick R; Karimi, Hussain H; Wilson, Kyle L; Puckett, Anthony D

    2011-01-24

    Fiber optic displacement sensors have many potential advantages over traditional displacement measurement techniques, including small size, immunity to electromagnetic interference, electrical isolation, and high resolution. In this report, we focus on an interferometric fiber optic sensor, where the gap between the fiber tip and the device under test forms a Fabry-Perot resonant cavity. An optical interrogator measures the reflected intensity at wavelengths ranging from 1510 to 1590 nm. The spacing between resonant frequencies allows us to determine the distance from the tip to the device under test. We consider ferrule connector angled physical contact (FC/APC), ferrule connector ultra physical contact (FC/UPC) and unpolished cleaved tips and compare their influence on sensor performance. A plane wave propagation model is proposed for predicting tip effects. Comparisons are made on the basis of sensor measurement range, resolution, and sensitivity to changes in test conditions. In this paper, we discuss the experimental setup, detail our analysis, and present test results with recommendations for the applications of each tip.

  11. Compression Myelopathy due to Proliferative Changes around C2 Pars Defects without Instability.

    PubMed

    Kimura, Tetsuya; Sakai, Toshinori; Tezuka, Fumitake; Abe, Mitsunobu; Yamashita, Kazuta; Takata, Yoichiro; Higashino, Kosaku; Sairyo, Koichi

    2016-06-01

    We report a case with compression myelopathy due to proliferative changes around the C2 pars defects without instability. A 69-year-old man presented with progressive clumsy hands and spastic gait. Plain radiographs showed bilateral spondylolysis (pars defects) at C2 and fusion between C2 and C3 spinous processes. Dynamic views revealed mobility through the pars defects, but there was no apparent instability. Computed tomography showed proliferative changes at the pars defects, which protruded into spinal canal. On magnetic resonance imaging, the spinal cord was compressed and intramedullary high signal change was found. A diagnosis of compression myelopathy due to proliferative changes around the C2 pars defects was made. We performed posterior decompression. Postoperatively, symptoms have been alleviated and images revealed sufficient decompression and no apparent instability. In patients with the cervical spondylolysis, myelopathy caused by instability or slippage have been periodically reported. The present case involving C2 spondylolysis is extremely rare. PMID:27340539

  12. Compression Myelopathy due to Proliferative Changes around C2 Pars Defects without Instability

    PubMed Central

    Kimura, Tetsuya; Tezuka, Fumitake; Abe, Mitsunobu; Yamashita, Kazuta; Takata, Yoichiro; Higashino, Kosaku; Sairyo, Koichi

    2016-01-01

    We report a case with compression myelopathy due to proliferative changes around the C2 pars defects without instability. A 69-year-old man presented with progressive clumsy hands and spastic gait. Plain radiographs showed bilateral spondylolysis (pars defects) at C2 and fusion between C2 and C3 spinous processes. Dynamic views revealed mobility through the pars defects, but there was no apparent instability. Computed tomography showed proliferative changes at the pars defects, which protruded into spinal canal. On magnetic resonance imaging, the spinal cord was compressed and intramedullary high signal change was found. A diagnosis of compression myelopathy due to proliferative changes around the C2 pars defects was made. We performed posterior decompression. Postoperatively, symptoms have been alleviated and images revealed sufficient decompression and no apparent instability. In patients with the cervical spondylolysis, myelopathy caused by instability or slippage have been periodically reported. The present case involving C2 spondylolysis is extremely rare. PMID:27340539

  13. Exploration of locomotion in the ParA/ParB system

    NASA Astrophysics Data System (ADS)

    Jindal, Lavisha; Emberly, Eldon

    2015-03-01

    In many bacteria the ParA/ParB system is responsible for actively segregating DNA during replication. ParB precessively moves by hydrolyzing DNA bound ParA-ATP forming a depleted ParA region in its wake. Recent in-vitro experiments have shown that a ParB covered bead can traverse a ParA bound DNA substrate. It has been suggested that the formation of a gradient in ParA leads to diffusion-ratchet like motion of the ParB bead but its origin and potential consequences requires investigation. We have developed a deterministic model for the in-vitro ParA/ParB system and show that any amount of spatial noise in ParA can lead to the spontaneous formation of its gradient. The velocity of the bead is independent of this noise but depends on the scale over which ParA exerts a force on the bead and the scale over which ParB hydrolyzes ParA from the substrate. There is a particular ratio of these scales at which the velocity is a maximum. We also explore the effects of cooperative vs independent rebinding of ParA to the substrate. Our model shows how the driving force for ParB originates and highlights necessary conditions for directed motion in the in-vitro system that may provide insight into the in-vivo behaviour of the ParA/ParB system.

  14. Modelisation du Signal Radar EN Milieu Stratifie et Evaluation de Techniques de Mesure de L'humidite du Sol

    NASA Astrophysics Data System (ADS)

    Boisvert, Johanne

    La presente etude se penche sur des problemes relies a l'echantillonnage de l'humidite de sol et a l'estimation du signal radar sur sols nus. Le travail se divise en deux volets. Le volet 1 evalue trois techniques de mesure de l'humidite du sol (gravimetrie, reflectometrie temporelle et sonde dielectrique) et deux protocoles d'echantillonnage. Dans le volet 2, un modele de simulation du signal en milieu stratifie est developpe, et les estimes de signal obtenus sont compares aux estimes bases uniquement sur une valeur moyenne d'humidite du sol prise sur une profondeur fixe d'echantillonnage. Les differences entre les deux estimes dependent de la frequence et du choix judicieux de la profondeur d'echantillonnage; elles sont plus importantes aux faibles angles et en polarisation HV, puis VV. Le modele de simulation a aussi ete utilise pour etudier la profondeur de penetration du signal et en deduire la profondeur optimale d'echantillonnage en tenant compte des caracteristiques du signal. Une variation de 25 ^circ de l'angle d'incidence a peu d'effet sur la profondeur de penetration en bande Ku; l'ecart reste inferieur ou egal a 0,5 cm en bande C mais peut atteindre 1,3 cm en bande L. L'impact de la polarisation est nul en bande Ku mais croi t avec l'angle d'incidence en bande C et L. A 50^circ, il est, en moyenne de 1 cm en bande C et de 2 cm en bande L. En polarisation VV, la profondeur croi t avec une augmentation de l'angle alors que l'effet est inverse en polarisation HH. Deux methodes pour estimer la profondeur d'echantillonnage en conditions operationnelles sont presentees. Lorsqu'on inverse un modele pour estimer l'humidite du sol a partir du signal, ces methodes permettent aussi d'estimer l'epaisseur de sol representee par l'humidite ainsi estimee.

  15. [Physiology of protease-activated receptors (PARs): involvement of PARs in digestive functions].

    PubMed

    Kawabata, A; Kuroda, R; Hollenberg, M D

    1999-10-01

    The protease-activated receptor (PAR), a G protein-coupled receptor present on cell surface, mediates cellular actions of extracellular proteases. Proteases cleave the extracellular N-terminal of PAR molecules at a specific site, unmasking and exposing a novel N-terminal, a tethered ligand, that binds to the body of receptor molecules resulting in receptor activation. Amongst four distinct PARs that have been cloned, PARs 1, 3 and 4 are activated by thrombin, but PAR-2 is activated by trypsin or mast cell tryptase. Human platelets express two distinct thrombin receptors, PAR-1 and PAR-4, while murine platelets express PAR-3 and PAR-4. Apart from roles of PARs in platelet activation, PARs are distributed to a number of organs in various species, predicting their physiological importance. We have been evaluating agonists specific for each PAR, using multiple procedures including a HEK cell calcium signal receptor desensitization assay. Using specific agonists that we developed, we found the following: 1) the salivary glands express PAR-2 mRNA and secret saliva in response to PAR-2 activation; 2) pancreatic juice secretion occurs following in vivo PAR-2 activation; 3) PAR-1 and PAR-2 modulate duodenal motility. Collectively, PAR plays various physiological and/or pathophysiological roles, especially in the digestive systems, and could be a novel target for drug development. PMID:10629876

  16. Effet Hall et Magnetisme des Alliages Amorphes Nickel-Zirconium Fabriques Par Pulverisation

    NASA Astrophysics Data System (ADS)

    Morel, Robert

    l'une et l'autre methode de fabrication. Il s'avere que le comportement intrinseque n'est pas different, mais que les echantillons pulverises sont plus sensibles a certaines anomalies de la structure que nous avons relevees et tente d'expliquer. L'etude des echantillons paramagnetiques permet de verifier que dans ces alliages le comportement de l'effet Hall apparent est la somme des contributions ordinaire, consequence de la force de Lorentz, et extraordinaire, etant donnee la tres forte valeur de coefficient de Hall extraordinaire notee dans ces systemes. Dans les alliages ferromagnetiques, l'etude systematique de l'aimantation en fonction de la temperature et de la composition est menee par le biais de la mesure de la resistivite de Hall. Elle permet de definir les principaux parametres magnetiques--temperature de Curie et aimantation--et de mettre en evidence le caractere itinerant du magnetisme et la contribution des fluctuations de spins. Ces mesures de resistivite de Hall dans les amorphes ferromagnetiques mettent aussi en lumiere un effet Hall extraordinaire qui se superpose a un effet Hall ordinaire semblable en grandeur a celui des cristallins. Il appert aussi que l'effet Hall extraordinaire est l'effet dominant, y compris qu dessus de la temperature de Curie. Cette etude du comportement de Hall et de quelques proprietes magnetiques des alliages amorphes NiZr contenant plus de 70% de nickel nous a donc permis de verifier que malgre la faible aimantation l'effet Hall extraordinaire est l'effet dominant, que l'effet Hall ordinaire est semblable a celui trouve dans les cristallins, et que l'ensemble de ces manifestations pouvait etre explique sans faire appel aux modeles quantiques.

  17. Par Pond Fish, Water, and Sediment Chemistry

    SciTech Connect

    Paller, M.H.; Wike, L.D.

    1996-06-01

    The objectives of this report are to describe the Par Pond fish community and the impact of the drawdown and refill on the community, describe contaminant levels in Par Pond fish, sediments, and water and indicate how contaminant concentrations and distributions were affected by the drawdown and refill, and predict possible effects of future water level fluctuations in Par Pond.

  18. Directed and persistent movement arises from mechanochemistry of the ParA/ParB system

    NASA Astrophysics Data System (ADS)

    Hu, Longhua; Vecchiarelli, Anthony G.; Mizuuchi, Kiyoshi; Neuman, Keir C.; Liu, Jian

    The segregation of DNA prior to cell division is essential for faithful genetic inheritance. In many bacteria, segregation of the low-copy-number plasmids involves an active partition system composed of ParA ATPase and its stimulator protein ParB. Recent experiments suggest that ParA/ParB system motility is driven by a diffusion-ratchet mechanism in which ParB-coated plasmid both creates and follows a ParA gradient on the nucleoid surface. However, the detailed mechanism of ParA/ParB-mediated directed and persistent movement remains unknown. We develop a theoretical model describing ParA/ParB-mediated motility. We show that the ParA/ParB system can work as a Brownian ratchet, which effectively couples the ATPase-dependent cycling of ParA-nucleoid affinity to the motion of the ParB bound cargo. Paradoxically, the resulting processive motion relies on quenching diffusive plasmid motion through a large number of transient ParA/ParB-mediated tethers to the nucleoid surface. Our work sheds light on a new emergent phenomenon in which non-motor proteins work collectively via mechanochemical coupling to propel cargos -- an ingenious solution shaped by evolution to cope with the lack of processive motor proteins in bacteria.

  19. The ParB-parS Chromosome Segregation System Modulates Competence Development in Streptococcus pneumoniae

    PubMed Central

    Attaiech, Laetitia; Minnen, Anita; Kjos, Morten; Gruber, Stephan

    2015-01-01

    ABSTRACT ParB proteins bind centromere-like DNA sequences called parS sites and are involved in plasmid and chromosome segregation in bacteria. We previously showed that the opportunistic human pathogen Streptococcus pneumoniae contains four parS sequences located close to the origin of replication which are bound by ParB. Using chromatin immunoprecipitation (ChIP), we found here that ParB spreads out from one of these parS sites, parS(−1.6°), for more than 5 kb and occupies the nearby comCDE operon, which drives competence development. Competence allows S. pneumoniae to take up DNA from its environment, thereby mediating horizontal gene transfer, and is also employed as a general stress response. Mutating parS(−1.6°) or deleting parB resulted in transcriptional up-regulation of comCDE and ssbB (a gene belonging to the competence regulon), demonstrating that ParB acts as a repressor of competence. However, genome-wide transcription analysis showed that ParB is not a global transcriptional regulator. Different factors, such as the composition of the growth medium and antibiotic-induced stress, can trigger the sensitive switch driving competence. This work shows that the ParB-parS chromosome segregation machinery also influences this developmental process. PMID:26126852

  20. L'engelure causée par le butane commercial au cours d’un accident industriel

    PubMed Central

    Assi-Dje Bi Dje, V.; Abhe, C.M.; Sie-Essoh, J.B.; Kouamé, K.; Vilasco, B.

    2014-01-01

    Summary Les engelures sont encore exceptionnelles en Afrique sub-saharienne, mais l’essor des industries pétrochimiques en rapport avec la promotion d’une large utilisation du gaz domestique (butane commercial) expose au risque de survenue de ce type de brûlures abusivement dites gelures. Nous rapportons un cas de brûlures au froid par gaz de pétrole liquéfié (GPL) en milieu professionnel dont le diagnostic de gravité et la prise en charge tardifs ont défavorisé l’évolution locale. Le respect des mesures de sécurité au sein des usines reste néanmoins le principal moyen de prévention de ce type de brûlures méconnues. PMID:26170791

  1. A Mars environmental survey (MESUR) - Feasibility of a low cost global approach

    NASA Technical Reports Server (NTRS)

    Hubbard, G. S.; Wercinski, Paul F.; Sarver, George L.; Hanel, Robert P.; Ramos, Ruben

    1991-01-01

    In situ measurements of Mars' surface and atmosphere are the objectives of a novel network mission concept called the Mars Environmental SURvey (MESUR). As envisioned, the MESUR mission will emplace a pole-to-pole global distribution of 16 landers on the Martian surface over three launch opportunites using medium-lift (Delta-class) launch vehicles. The basic concept is to deploy small free-flying probes which would directly enter the Martian atmosphere, measure the upper atmospheric structure, image the local terrain before landing, and survive landing to perform meteorology, seismology, surface imaging, and soil chemistry measurements. Data will be returned via dedicated relay orbiter or direct-to-earth transmission. The mission philosophy is to: (1) 'grow' a network over a period of years using a series of launch opportunities; (2) develop a level-of-effort which is flexible and responsive to a broad set of objectives; (3) focus on Mars science while providing a solid basis for future human presence; and (4) minimize overall project cost and complexity wherever possible.

  2. Parallel Climate Analysis Toolkit (ParCAT)

    Energy Science and Technology Software Center (ESTSC)

    2013-06-30

    The parallel analysis toolkit (ParCAT) provides parallel statistical processing of large climate model simulation datasets. ParCAT provides parallel point-wise average calculations, frequency distributions, sum/differences of two datasets, and difference-of-average and average-of-difference for two datasets for arbitrary subsets of simulation time. ParCAT is a command-line utility that can be easily integrated in scripts or embedded in other application. ParCAT supports CMIP5 post-processed datasets as well as non-CMIP5 post-processed datasets. ParCAT reads and writes standard netCDF files.

  3. Capteur de CO{2} à fibres optiques par absorption moléculaire à 4,3 μm

    NASA Astrophysics Data System (ADS)

    Bendamardji, S.; Alayli, Y.; Huard, S.

    1996-04-01

    This paper describes a remote optical fibre sensor for the carbon dioxide detection by molecular absorption in the near infrared (4.3 μm) corresponding to fundamental mode ν3. To overcome the problem of the strong attenuation signal of optical fibre in the near infrared, we have used the opto-suppling technique which changes the working wavelength from 4.3 μm to 860 nm and permits the use of standard optical fibre 50/125. The simulation of absorption has been obtained by original modelisation of the absorption spectrum and the establishment of the calibration curves takes to the sensor to detect a partial pressures greater than 100 μbar with a minimal error margin of 100 μbar, which is acceptable considering the future use of the device. The sensor has been designed to monitor the CO{2} rate in enriched greenhouses. Cet article décrit un capteur à fibres optiques de gaz carbonique par absorption moléculaire dans l'infrarouge moyen (4,3 μm) correspondant au mode fondamental ν3. La liaison entre le site de mesure et le site de contrôle est assurée par un fibre optique standard 50/125 après une transposition de longueur d'onde de 4,3 μm à 860 nm par opto-alimentation. La simulation de l'absorption a été obtenue par modélisation originale du spectre d'absorption et l'établissement des courbes d'étalonnage prévoit une marge d'erreur minimale de 100 μbar, ce qui est suffisant pour l'application du dispositif à la régulation de taux CO{2} dans les serres agricoles enrichies par de gaz.

  4. Directed and persistent movement arises from mechanochemistry of the ParA/ParB system.

    PubMed

    Hu, Longhua; Vecchiarelli, Anthony G; Mizuuchi, Kiyoshi; Neuman, Keir C; Liu, Jian

    2015-12-22

    The segregation of DNA before cell division is essential for faithful genetic inheritance. In many bacteria, segregation of low-copy number plasmids involves an active partition system composed of a nonspecific DNA-binding ATPase, ParA, and its stimulator protein ParB. The ParA/ParB system drives directed and persistent movement of DNA cargo both in vivo and in vitro. Filament-based models akin to actin/microtubule-driven motility were proposed for plasmid segregation mediated by ParA. Recent experiments challenge this view and suggest that ParA/ParB system motility is driven by a diffusion ratchet mechanism in which ParB-coated plasmid both creates and follows a ParA gradient on the nucleoid surface. However, the detailed mechanism of ParA/ParB-mediated directed and persistent movement remains unknown. Here, we develop a theoretical model describing ParA/ParB-mediated motility. We show that the ParA/ParB system can work as a Brownian ratchet, which effectively couples the ATPase-dependent cycling of ParA-nucleoid affinity to the motion of the ParB-bound cargo. Paradoxically, this resulting processive motion relies on quenching diffusive plasmid motion through a large number of transient ParA/ParB-mediated tethers to the nucleoid surface. Our work thus sheds light on an emergent phenomenon in which nonmotor proteins work collectively via mechanochemical coupling to propel cargos-an ingenious solution shaped by evolution to cope with the lack of processive motor proteins in bacteria. PMID:26647183

  5. Directed and persistent movement arises from mechanochemistry of the ParA/ParB system

    PubMed Central

    Hu, Longhua; Vecchiarelli, Anthony G.; Mizuuchi, Kiyoshi; Neuman, Keir C.; Liu, Jian

    2015-01-01

    The segregation of DNA before cell division is essential for faithful genetic inheritance. In many bacteria, segregation of low-copy number plasmids involves an active partition system composed of a nonspecific DNA-binding ATPase, ParA, and its stimulator protein ParB. The ParA/ParB system drives directed and persistent movement of DNA cargo both in vivo and in vitro. Filament-based models akin to actin/microtubule-driven motility were proposed for plasmid segregation mediated by ParA. Recent experiments challenge this view and suggest that ParA/ParB system motility is driven by a diffusion ratchet mechanism in which ParB-coated plasmid both creates and follows a ParA gradient on the nucleoid surface. However, the detailed mechanism of ParA/ParB-mediated directed and persistent movement remains unknown. Here, we develop a theoretical model describing ParA/ParB-mediated motility. We show that the ParA/ParB system can work as a Brownian ratchet, which effectively couples the ATPase-dependent cycling of ParA–nucleoid affinity to the motion of the ParB-bound cargo. Paradoxically, this resulting processive motion relies on quenching diffusive plasmid motion through a large number of transient ParA/ParB-mediated tethers to the nucleoid surface. Our work thus sheds light on an emergent phenomenon in which nonmotor proteins work collectively via mechanochemical coupling to propel cargos—an ingenious solution shaped by evolution to cope with the lack of processive motor proteins in bacteria. PMID:26647183

  6. La structure de l'eau liquide: Une etude thermique par spectroscopie infrarouge

    NASA Astrophysics Data System (ADS)

    Larouche, Pascal

    mesures de diffraction des rayons X ont aussi ete analysees. Les abondances tirees de l'analyse par facteurs des spectres infrarouges permettent de calculer les fonctions de distributions radiales des deux especes. Ces fonctions offrent la possibilite de connaitre les distances relatives entre les atomes. Avec ces distances en main, l'architecture des deux especes peut etre schematisee. Ces resultats originaux, combines a ceux issus de la spectroscopie infrarouge, permettent de montrer que la premiere espece est bien organisee, c'est-a-dire que le cube defini par un atome d'oxygene et les quatre autres atomes d'oxygene avec lesquels il est en liens-H est regulier, alors que pour l'espece chaude, les dimensions du cubes sont irregulieres. La comparaison entre les deux especes montre qu'elles etablissent toujours quatre liens-H et que leurs differences resident uniquement dans la geometrie des cubes. Finalement, deux hypotheses sont formulees comme fondement d'un modele de la structure de l'eau liquide. Premierement, l'empilement des cubes des deux especes permet de representer l'eau a toutes les temperatures, l'espece froide etant garante de la stabilite du liquide, alors que l'espece chaude a un effet destabilisant; et deuxiemement, le saut du proton stabilise les liens-H, de telle sorte que lorsque l'espece chaude devient trop abondante, ces defauts provoquent un arret des sauts de protons et les liens-H ainsi affaiblis se brisent et le liquide s'evapore.

  7. Role of PAR-4 in ovarian cancer.

    PubMed

    Meynier, Sonia; Kramer, Marianne; Ribaux, Pascale; Tille, Jean-Christophe; Delie, Florence; Petignat, Patrick; Cohen, Marie

    2015-09-01

    Prostate apoptosis response-4 (PAR-4) is considered as a tumour suppressor due to its ability to selectively induce cell apoptosis in most cancer cells. However little is known about the role of PAR-4 in ovarian cancer. In this study, we investigated for the first time the role of PAR-4 in ovarian carcinogenesis. We showed that PAR-4 mRNA level is not significantly different between healthy and cancer ovarian cells. Immunohistochemistry on ovarian tissue showed that ovarian cancer cells are positive for PAR-4 nuclear and cytoplasmic staining whereas ovarian healthy cells are negative for PAR-4 nuclear staining. We then studied the role of PAR-4 in cell apoptosis. We determined that PAR-4 induces cell apoptosis in response to stimuli, in vitro, but is also involved in the relocation of GRP78 from endoplasmic reticulum to the cell surface of ovarian cancer cell line (SKOV-3 cells). In ovo, PAR-4 decreases ovarian tumour development and increases the response to taxol treatment. These observations suggest that PAR-4 is a very interesting therapeutic target against ovarian carcinogenesis. PMID:26246468

  8. Role of PAR-4 in ovarian cancer

    PubMed Central

    Meynier, Sonia; Kramer, Marianne; Ribaux, Pascale; Tille, Jean-Christophe; Delie, Florence; Petignat, Patrick; Cohen, Marie

    2015-01-01

    Prostate apoptosis response-4 (PAR-4) is considered as a tumour suppressor due to its ability to selectively induce cell apoptosis in most cancer cells. However little is known about the role of PAR-4 in ovarian cancer. In this study, we investigated for the first time the role of PAR-4 in ovarian carcinogenesis. We showed that PAR-4 mRNA level is not significantly different between healthy and cancer ovarian cells. Immunohistochemistry on ovarian tissue showed that ovarian cancer cells are positive for PAR-4 nuclear and cytoplasmic staining whereas ovarian healthy cells are negative for PAR-4 nuclear staining. We then studied the role of PAR-4 in cell apoptosis. We determined that PAR-4 induces cell apoptosis in response to stimuli, in vitro, but is also involved in the relocation of GRP78 from endoplasmic reticulum to the cell surface of ovarian cancer cell line (SKOV-3 cells). In ovo, PAR-4 decreases ovarian tumour development and increases the response to taxol treatment. These observations suggest that PAR-4 is a very interesting therapeutic target against ovarian carcinogenesis. PMID:26246468

  9. Resonances and resonance widths

    SciTech Connect

    Collins, T.

    1986-05-01

    Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances.

  10. Etude de la formation de resonances electroniques et de leur role dans la fragmentation neutre de molecules d'interet biologique

    NASA Astrophysics Data System (ADS)

    Lepage, Martin

    1998-12-01

    Cette these est presentee a la Faculte de medecine de l'Universite de Sherbrooke en vue de l'obtention du grade de Ph.D. en Radiobiologie. Elle contient des resultats experimentaux enregistres avec un spectrometre d'electrons a haute resolution. Ces resultats portent sur la formation de resonances electroniques en phase condensee et de differents canaux pour leur decroissance. En premier lieu, nous presentons des mesures d'excitations vibrationnelles de l'oxygene dilue en matrice d'argon pour des energies des electrons incidents de 1 a 20 eV. Les resultats suggerent que le temps de vie des resonances de l'oxygene est modifie par la densite d'etats d'electrons dans la bande de conduction de l'argon. Nous presentons aussi des spectres de pertes d'energie d'electrons des molecules de tetrahydrofuranne (THF) et d'acetone. Dans les deux cas, la position en energie des pertes associees aux excitations vibrationnelles est en excellent accord avec les resultats trouves dans la litterature. Les fonctions d'excitation de ces modes revelent la presence de plusieurs nouvelles resonances electroniques. Nous comparons les resonances du THF et celles de la molecule de cyclopentane en phase gazeuse. Nous proposons une origine commune aux resonances ce qui implique qu'elles ne sont pas necessairement attribuees a l'excitation des electrons non-apparies de l'oxygene du THF. Nous proposons une nouvelle methode basee sur la spectroscopie par pertes d'energie des electrons pour detecter la production de fragments neutres qui demeurent a l'interieur d'un film mince condense a basse temperature. Cette methode se base sur la detection des excitations electroniques du produit neutre. Nous presentons des resultats de la production de CO dans un film de methanol. Le taux de production de CO en fonction de l'energie incidente des electrons est calibre en termes d'une section efficace totale de diffusion des electrons. Les resultats indiquent une augmentation lineaire du taux de production de

  11. La projection par plasma : une revue

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Grimaud, A.; Vardelle, A.; Vardelle, M.

    are presented in the fields of aeronautics and mechanics. La qualité d'un dépôt projete par plasma dépend de nombreux paramètres que l'on commence à mieux appréhender du fait des progrès de la modélisation et de la métrologie tant des écoulements plasmas que des transferts plasma-particules ou que des conditions d'écrasement et de refroidissement des particules lors de leur impact sur le substrat ou les couches déjà déposées. Les techniques de mesure utilisdes et leurs limitations sont d'abord rappelées tant pour les jets de plasma que pour les particules en vol et l'importance des différents phénomènes intervenant dans les transferts plasma-particules est soulignée : gradients de température et de concentration d'espèces chimiques très élevés autour des particules, effets de propagation de la chaleur, notamment pour les particules céramiques, effet d'évaporation, effet de raréfaction sensible dès la pression atmosphérique. Les problèmes de distribution de taille et de vitesse d'injection des particules sont également abordés car ils conditionnent les distributions de trajectoires et donc le traitement des particules dans le jet de plasma. La génération du plasma montre d'une part 1'influence considérable de l'injection du gaz, de sa nature, du dessin de la chambre d'arc et de la tuyère ainsi que du pompage de l'air ambiant sur la longueur des jets de plasma d'arc et d'autre part les problèmes d'injection pour éviter le couplage avec la décharge dans les jets de plasmas R.E Tout ceci est illustré avec des exemples de dépôt d'alumine, de zircone, de cermet carbure et de nickel. L'écrasement des particules est ensuite abordé avec les problèmes de réactions chimiques, de trempe ultra-rapide et donc de structure cristalline des dépôts, d'adhdsion mais aussi de containtes résiduelles et de leur contrôle via les gradients de température dans les dépôts pendant le tir. Enfin quelques applications actuelles sont pr

  12. PAR for the Course: A Congruent Pedagogical Approach for a PAR Methods Class

    ERIC Educational Resources Information Center

    Hammond, Joyce D.; Hicks, Maria; Kalman, Rowenn; Miller, Jason

    2005-01-01

    In the past two years, three graduate students and a senior faculty member have co-taught a participatory action research (PAR) course to undergraduate and graduate students. In this article the co-teachers advocate a set of pedagogical principles and practices in a PAR-oriented classroom that establishes congruency with community PAR projects in…

  13. Douleurs induites par les soins: la réalité au Centre Hospitalier Universitaire de Befelatanana Antananarivo, Madagascar

    PubMed Central

    Mahavivola, Ernestho-Ghoud Indretsy; Olivah, Razanaparany Miarisoa Mireille; Mihary, Dodo; Hendriniaina, Rakotoharivelo; Lalao, Randriamboavonjy Rado; Henintsoa, Rakotonirainy Oliva; Fahafahantsoa, Rapelanoro Rabenja

    2014-01-01

    La douleur induite par les soins correspond à la douleur survenant lors des actes à visé diagnostique et/ou thérapeutique. A notre connaissance, nous n'avons pas encore des données disponibles pour les douleurs induites par les soins à l'Hôpital de Befelatanana. Nos objectifs étaient de décrire le profil épidémiologique de la douleur induite par les soins, d'identifier les principaux facteurs influençant sur l'intensité de la douleur et leurs retentissements chez les patients. Il s'agissait d'une étude rétrospective, transversale type un jour donné menée dans les douze services de Médecines au Centre Hospitalier Universitaire de Befelatanana en Novembre 2013. Cent deux patients ont été retenus dans l’étude et trois cent vingt trois actes douloureux étaient enregistrés. La fréquence de la douleur induite par les soins était de 69,86%. Le genre féminin prédominait dans 52% des cas (n = 53) avec un sex-ratio à 0,92. L’âge moyen était de 46 ans. Les ponctions vasculaires étaient l'acte prédominant dans 49,54% (n = 109) des cas. Les infirmiers réalisaient les soins dans 47,05% (n = 48) des cas. L'information verbale était la mesure préventive utilisée dans 57,84% des cas (n = 59). Le transport par marche à pied et au dos représentait 16,67% des cas (n = 17). Les patients naïfs des gestes étaient plus anxieux. Ces patients gardaient de mauvais souvenir dans 64,71% des cas (n = 66). La fréquence de douleur induite par les soins était trop élevée. Un effort important est nécessaire pour réduire la douleur induite par les soins PMID:25932071

  14. Developpement d'un systeme pour la mesure du taux de vide dans un ecoulement diphasique par une methode utilisant des micro-ondes

    NASA Astrophysics Data System (ADS)

    Pochet, Steven

    The measurement of the void fraction is an important parameter in many industrial fields. Whether it is to prevent the phenomenon of critical heat flux in heat tube of thermal power plants, the explosion of gas pockets in oil rigs’ pipes or to detect bubbles in medical catheters, the knowledge of the void fraction can be a key parameter in many diverse applications. Several invasive and non-invasive measurements techniques have been developed these last decades and are based on the difference between the physical properties of liquid and gas. Some of these techniques are not always possible to implement due to restrictions in the geometry of tubes or regulatory standards limiting their use. Throughout this work we propose a new non-invasive void fraction measurement technique based on the reflection of electromagnetic waves on the water-air interface of the mixture. The reflection of electromagnetic wave is induced by a change in the impedance of the propagation medium. The impedance is function of the dielectric properties of the medium. The characteristics of air and water being distinct, it is possible to calculate the complex reflection coefficient at the interface of a double phase mixture. To this end, mathematical modeling of the response of an electromagnetic wave in a tube containing a two phase mixture was made using the model of transmission lines, applicable to microwave frequencies we use. The effects of the amount of air in water and the position of the bubbles in the section of the tube were simulated. It was shown that the phase of the reflected wave was sensitive to the position of bubbles in the tube’s section and that the magnitude of the reflection coefficient varied with the mixture’s void fraction. Subsequently, we designed and built a six-ports reflectometer operating at 2.45 GHz. This system allows the processing and calculation of the reflected wave from the incident wave. A six-ports network, a patch antenna, a wave generator and an amplifier were simulated using HFSS and ADS software. They were then built using the technology of micro-strips on dielectric laminates and the entire system was then calibrated at 6 different frequencies near 2.45 GHz. To this end, we used 4 and 5 loads calibration algorithms that gave us calibrated results with less than 2 % errors. Afterwards, the system was implemented: the antenna was placed tangent to the wall of a vertical tube and connected to the six-ports which was connected to a computer recording and displaying the results in real time. A valve positioned under the tube allows air into the tube and to vary the flow rate. The results showed that the system was sensitive to changes in void fraction from 1% and followed the predictions of the simulated model to a void fraction of about 10%. Possibly du to a change in the structure of the flow for a void fraction of 10%, the signal no longer varies monotonically with respect to the increasing void fraction possibly because of a change in the flow’s configuration. It was shown that the Rayleigh scattering phenomena of air bubbles was involved in the reflection coefficient response. Pictures of the stream at various void fraction state were taken and confirmed a change in the flow’s configuration. By placing a Plexiglas rod to simulate a flow geometry located in the section of the tube, it was noted that the change in phase of the reflected wave was the same as the model when the rod was placed in an empty tube (very few attenuation loss environment). Hence, it is possible to determine the distance of an object in a section of tube from the measurement of the reflected wave’s phase. When the rod is in a very absorbent medium such as water, it is possible to detect a moving rod when it is sufficiently close to the antenna (less than two wavelengths) thanks again to the phase variation. However, detection is still much more difficult due to the absorption of water and ca

  15. Ouverture mécanique de la molécule d'ADN par micro-manipulation et mesure de force

    NASA Astrophysics Data System (ADS)

    Bockelmann, Ulrich; Essevaz-Roulet, B.; Thomen, Philippe; Heslot, François

    In this paper we summarize part of our work on the mechanical unzipping of DNA. We have prepared molecular constructions which allow us to attach the two complementary strands of one end of a single DNA molecule of the bacteriophage λ separately to a glass microscope slide and a microscopic bead. In a first series of experiments, a soft microneedle acting as a force sensor is attached to the bead and its deflection is measured with an optical microscope. In a second series, we use an optical trapping interferometer to capture the bead and to measure its displacement to nm resolution. The sample is slowly displaced with respect to the force measurement device, leading to a progressive opening of the double helix. The force measured during this mechanical opening shows a characteristic variation which is related to the base pair sequence of the DNA molecule. To cite this article: U. Bockelmann et al., C. R. Physique 3 (2002) 585-594.

  16. Mesures in situ par infiltrométrie des propriétés hydrodynamiques des sols de Mnasra (Maroc)

    NASA Astrophysics Data System (ADS)

    Tamoh, Karim; Maslouhi, Abdellatif

    2004-04-01

    The aim of this work is the field hydraulic characterisation of Mnasra soils in northern Morocco, which represents an essential step to study the hydraulic and chemical transports through the vadose zone. We have used a tension infiltrometer associated with a transient axisymmetric infiltration method to determine the hydraulic conductivity, which reduces the duration of measurements. This allows us to characterise a large area with many measurements. Parameters of the characteristic functions K( h) and θ( h) are estimated for six different soils belonging to two geomorphologically different domains: a sandy zone and an alluvial plain. To cite this article: K. Tamoh, A. Maslouhi, C. R. Geoscience 336 (2004).

  17. Par Pond vegetation status Summer 1995 -- Summary

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1996-01-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the newly emergent, shoreline aquatic plant communities of Par Pond began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level. These surveys continued in July, September, and late October, 1995. Communities similar to the pre-drawdown, Par Pond aquatic plant communities are becoming re-established. Emergent beds of maidencane, lotus, waterlily, and watershield are extensive and well developed. Cattail occurrence continued to increase during the summer, but large beds common to Par Pond prior to the drawdown have not formed. Estimates from SPOT HRV, remote sensing satellite data indicated that as much as 120 hectares of emergent wetlands vegetation may have been present along the Par Pond shoreline by early October, 1995. To track the continued development of macrophytes in Par Pond, future surveys throughout 1996 and 1997, along with the continued evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned.

  18. Targeting of peptide conjugated magnetic nanoparticles to urokinase plasminogen activator receptor (uPAR) expressing cells

    NASA Astrophysics Data System (ADS)

    Hansen, Line; Unmack Larsen, Esben Kjær; Nielsen, Erik Holm; Iversen, Frank; Liu, Zhuo; Thomsen, Karen; Pedersen, Michael; Skrydstrup, Troels; Nielsen, Niels Chr.; Ploug, Michael; Kjems, Jørgen

    2013-08-01

    Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific targeting peptide onto polyethylene glycol (PEG) coated USPIO nanoparticles by click chemistry resulted in a five times higher uptake in vitro in a uPAR positive cell line compared to nanoparticles carrying a non-binding control peptide. In accordance with specific receptor-mediated recognition, a low uptake was observed in the presence of an excess of ATF, a natural ligand for uPAR. The uPAR specific magnetic nanoparticles can potentially provide a useful supplement for tumor patient management when combined with MRI and drug delivery.Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific

  19. ParAB Partition Dynamics in Firmicutes: Nucleoid Bound ParA Captures and Tethers ParB-Plasmid Complexes

    PubMed Central

    Lioy, Virginia S.; Volante, Andrea; Soberón, Nora E.; Lurz, Rudi; Ayora, Silvia; Alonso, Juan C.

    2015-01-01

    In Firmicutes, small homodimeric ParA-like (δ2) and ParB-like (ω2) proteins, in concert with cis-acting plasmid-borne parS and the host chromosome, secure stable plasmid inheritance in a growing bacterial population. This study shows that (ω:YFP)2 binding to parS facilitates plasmid clustering in the cytosol. (δ:GFP)2 requires ATP binding but not hydrolysis to localize onto the cell’s nucleoid as a fluorescent cloud. The interaction of (δ:CFP)2 or δ2 bound to the nucleoid with (ω:YFP)2 foci facilitates plasmid capture, from a very broad distribution, towards the nucleoid and plasmid pairing. parS-bound ω2 promotes redistribution of (δ:GFP)2, leading to the dynamic release of (δ:GFP)2 from the nucleoid, in a process favored by ATP hydrolysis and protein-protein interaction. (δD60A:GFP)2, which binds but cannot hydrolyze ATP, also forms unstable complexes on the nucleoid. In the presence of ω2, (δD60A:GFP)2 accumulates foci or patched structures on the nucleoid. We propose that (δ:GFP)2 binding to different nucleoid regions and to ω2-parS might generate (δ:GFP)2 gradients that could direct plasmid movement. The iterative pairing and unpairing cycles may tether plasmids equidistantly on the nucleoid to ensure faithful plasmid segregation by a mechanism compatible with the diffusion-ratchet mechanism as proposed from in vitro reconstituted systems. PMID:26161642

  20. Contrôle d'une machine asynchrone par estimation robuste de la vitesse

    NASA Astrophysics Data System (ADS)

    Roboam, X.; Hapiot, J. C.; de Fornel, B.; Andrieux, C.

    1992-03-01

    This paper describes the study and the implementation of a variable speed drive for induction motor with no mechanical sensor. Power is supplied by a current-controlled voltage-source inverter. The lack of information (only two line-current sensors) requires an accurate and reliable reconstitution of the main quantities not sensed (flux, speed, torque). The results obtained show the excellent quality of the estimated speed, whatever the operating condition and despite the perturbations applied to the system. This study finally leads to the construction of a prototype. Cet article décrit l'étude et la mise en oeuvre d'un variateur de vitesse pour machine asynchrone sans capteur mécanique et alimentée par un onduleur de tension cotrôlé en courant. Le manque d'information (2 capteurs de courants de ligne uniquement) nécessite la reconstitution fiable et précise des grandeurs fondamentales non mesurées (flux, vitesse, couple). Les résultats obtenus montrent notamment l'excellente qualité de l'estimation de vitesse, quel que soit le point de fonctionnement et en dépit des perturbations auxquelles le système est soumis. Cette étude donne lieu à la réalisation d'un variateur prototype.

  1. RTG Impact Response to Hard Landing During Mars Environmental Survey (MESUR) Mission

    SciTech Connect

    Schock, Alfred; Mukunda, Meera

    1992-03-06

    The National Aeronautics and Space Administration (NASA) is studying a seven-year robotic mission (MESUR, Mars Environmental Survey) for the seismic, meteorological, and geochemical exploration of the Martian surface by means of a network of ~16 small, inexpensive landers spread from pole to pole. To permit operation at high Martian latitudes, NASA has tentatively decided to power the landers with small RTGs (Radioisotope Thermoelectric Generators). To support the NASA mission study, the Department of Energy's Office of Special Applications commissioned Fairchild to perform specialized RTG design studies. Those studies indicated that the cost and complexity of the mission could be significantly reduced if the RTGs had sufficient impact resistance to survive ground impact of the landers without retrorockets. Fairchild designs of RTGs configured for high impact resistance were reported previously. Since the, the size, configuration, and impact velocity of the landers and the power level and integration mode of the RTGs have changed substantially, and the previous impact analysis has been changed substantially, and the previous impact analysis has been updated accordingly. The analytical results, reported here, indicate that a lander by itself experiences much higher g-loads than the lander with an integral penetrator; but that minor modifications of the shape of the lander can very substantially reduce the maximum g-load during landing, thus eliminating the need for retrorockets for RTG survival. There are three copies in the file and the Original Artwork is stored in the ESD files.

  2. Comparative cactus architecture and par interception

    SciTech Connect

    Geller, G.N.; Nobel, P.S. )

    1987-07-01

    Because CO{sup 2} uptake by cacti can be limited by low levels of photosynthetically active radiation (PAR) and because plant form affects PAR interception, various cactus forms were studied using a computer model, field measurements, and laboratory phototropic studies. Model predictions indicated that CO{sub 2} uptake by individual stems at an equinox was greatest when the stem were vertical, but at the summer and the winter solstice CO{sub 2} uptake was greatest for stems titled 30{degree} away from the equator. Stem tilting depended on form and taxonomic group. Not only can the shape of cacti be affected by PAR, but also shape influences PAR interception and hence CO{sub 2} uptake.

  3. Radioecological implications of the Par Pond drawdown

    SciTech Connect

    Hickey, H.; Whicker, F.W.

    1991-12-05

    The drawdown of the Par Pond reservoir created dramatic alterations in this formerly stable lentic ecosystem. In addition, the radiation environment at Par Pond has changed significantly because of the exposure of Cesium 137-contaminated sediments and the appearance of new transport pathways to the terrestrial environment. In response to this situation, SREL was asked to study the radioecological implications of the reservoir drawdown. This report contains the objectives, methods, and results of the SREL study.

  4. Modelisation frequentielle de la permittivite du beton pour le controle non destructif par georadar

    NASA Astrophysics Data System (ADS)

    Bourdi, Taoufik

    Le georadar (Ground Penetrating Radar (GPR)) constitue une technique de controle non destructif (CND) interessante pour la mesure des epaisseurs des dalles de beton et la caracterisation des fractures, en raison de ses caracteristiques de resolution et de profondeur de penetration. Les equipements georadar sont de plus en plus faciles a utiliser et les logiciels d'interpretation sont en train de devenir plus aisement accessibles. Cependant, il est ressorti dans plusieurs conferences et ateliers sur l'application du georadar en genie civil qu'il fallait poursuivre les recherches, en particulier sur la modelisation et les techniques de mesure des proprietes electriques du beton. En obtenant de meilleures informations sur les proprietes electriques du beton aux frequences du georadar, l'instrumentation et les techniques d'interpretation pourraient etre perfectionnees plus efficacement. Le modele de Jonscher est un modele qui a montre son efficacite dans le domaine geophysique. Pour la premiere fois, son utilisation dans le domaine genie civil est presentee. Dans un premier temps, nous avons valide l'application du modele de Jonscher pour la caracterisation de la permittivite dielectrique du beton. Les resultats ont montre clairement que ce modele est capable de reproduire fidelement la variation de la permittivite de differents types de beton sur la bande de frequence georadar (100 MHz-2 GHz). Dans un deuxieme temps, nous avons montre l'interet du modele de Jonscher en le comparant a d'autres modeles (Debye et Debye-etendu) deja utilises dans le domaine genie civil. Nous avons montre aussi comment le modele de Jonscher peut presenter une aide a la prediction de l'efficacite de blindage et a l'interpretation des ondes de la technique GPR. Il a ete determine que le modele de Jonscher permet de donner une bonne presentation de la variation de la permittivite du beton dans la gamme de frequence georadar consideree. De plus, cette modelisation est valable pour differents

  5. Structural analysis of the ParR/parC plasmid partition complex.

    PubMed

    Møller-Jensen, Jakob; Ringgaard, Simon; Mercogliano, Christopher P; Gerdes, Kenn; Löwe, Jan

    2007-10-17

    Accurate DNA partition at cell division is vital to all living organisms. In bacteria, this process can involve partition loci, which are found on both chromosomes and plasmids. The initial step in Escherichia coli plasmid R1 partition involves the formation of a partition complex between the DNA-binding protein ParR and its cognate centromere site parC on the DNA. The partition complex is recognized by a second partition protein, the actin-like ATPase ParM, which forms filaments required for the active bidirectional movement of DNA replicates. Here, we present the 2.8 A crystal structure of ParR from E. coli plasmid pB171. ParR forms a tight dimer resembling a large family of dimeric ribbon-helix-helix (RHH)2 site-specific DNA-binding proteins. Crystallographic and electron microscopic data further indicate that ParR dimers assemble into a helix structure with DNA-binding sites facing outward. Genetic and biochemical experiments support a structural arrangement in which the centromere-like parC DNA is wrapped around a ParR protein scaffold. This structure holds implications for how ParM polymerization drives active DNA transport during plasmid partition. PMID:17898804

  6. Techniques for measuring intercepted and absorbed PAR in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.

    1984-01-01

    The quantity of radiation potentially available for photosynthesis that is captured by the crop is best described as absorbed photosynthetically active radiation (PAR). Absorbed PAR (APAR) is the difference between descending and ascending fluxes. The four components of APAR were measured above and within two planting densities of corn (Zea mays L.) and several methods of measuring and estimating APAR were examined. A line quantum sensor that spatially averages the photosynthetic photon flux density provided a rapid and portable method of measuring APAR. PAR reflectance from the soil (Typic Argiaquoll) surface decreased from 10% to less than 1% of the incoming PAR as the canopy cover increased. PAR reflectance from the canopy decreased to less than 3% at maximum vegetative cover. Intercepted PAR (1 - transmitted PAR) generally overestimated absorbed PAR by less than 4% throughout most of the growing season. Thus intercepted PAR appears to be a reasonable estimate of absorbed PAR.

  7. RTGs Using PbTe/TAGSThermoelectric Elements for Mars Environmentatl Survey (MESUR) Mission

    SciTech Connect

    Schock, Alfred

    1992-07-01

    The paper describes the results of studies on an RTG option for powering the global network of unmanned landers for NASA's Mars Environmental Survey (MESUR) mission. RTGs are essentially unaffected by diurnal and seasonal variations, Martian sandstorms, and landing site latitudes, and their waste heat can stabilize the temperatures of the landers and their payload. The RTG designs described in this paper are based on PbTe/TAGS Thermoelectric elements, in contrast to the SiGe-based RTGs the author described in previous publications. The RTGs described here differ not only in the choice of thermoelectric materials but also in the use of much lower operating temperatures, conductive rather than radiative heat transfer, an inert cover gas instead of vacuum in the RGG's converter, and fibrous instead of multifoil thermal insulation. As in a previous Teledyne design, the Fairchild designs described in this paper employ flight-proven General Purpose Heat Source modules and Close-Pack Arrays of thermoelectric converter modules. Illustrative point designs of RTGs producing 41 and 51 watts(e) at 28 volts are presented. The presented performance parameters were derived by detailed thermal, thermoelectric, and electrical analyses (including radiator geometry optimization) described in the paper. The Fairchild study resulted in modifications of the Teledyne design to permit scale-up to higher power levels, and to ensure adequate fuel clad ductility at launch temperatures and adequate thermal conductance from the thermoelectric cold ends to the RTG housing. There are three duplicate copies. One copy is in the FSC-ESD files.

  8. Stabilizing a flexible interdomain hinge region harboring the SMB binding site drives uPAR into its closed conformation.

    PubMed

    Zhao, Baoyu; Gandhi, Sonu; Yuan, Cai; Luo, Zhipu; Li, Rui; Gårdsvoll, Henrik; de Lorenzi, Valentina; Sidenius, Nicolai; Huang, Mingdong; Ploug, Michael

    2015-03-27

    The urokinase-type plasminogen activator receptor (uPAR) is a multidomain glycolipid-anchored membrane protein, which facilitates extracellular matrix remodeling by focalizing plasminogen activation to cell surfaces via its high-affinity interaction with uPA. The modular assembly of its three LU (Ly6/uPAR-like) domains is inherently flexible and binding of uPA drives uPAR into its closed conformation, which presents the higher-affinity state for vitronectin thus providing an allosteric regulatory mechanism. Using a new class of epitope-mapped anti-uPAR monoclonal antibodies (mAbs), we now demonstrate that the reciprocal stabilization is indeed also possible. By surface plasmon resonance studies, we show that these mAbs and vitronectin have overlapping binding sites on uPAR and that they share Arg91 as hotspot residue in their binding interfaces. The crystal structure solved for one of these uPAR·mAb complexes at 3.0Å clearly shows that this mAb preselects the closed uPAR conformation with an empty but correctly assembled large hydrophobic binding cavity for uPA. Accordingly, these mAbs inhibit the uPAR-dependent lamellipodia formation and migration on vitronectin-coated matrices irrespective of the conformational status of uPAR and its occupancy with uPA. This is the first study to the best of our knowledge, showing that the dynamic assembly of the three LU domains in uPARwt can be driven toward the closed form by an external ligand, which is not engaging the hydrophobic uPA binding cavity. As this binding interface is also exploited by the somatomedin B domain of vitronectin, therefore, this relationship should be taken into consideration when exploring uPAR-dependent cell adhesion and migration in vitronectin-rich environments. PMID:25659907

  9. ParCAT: Parallel Climate Analysis Toolkit

    SciTech Connect

    Smith, Brian E.; Steed, Chad A.; Shipman, Galen M.; Ricciuto, Daniel M.; Thornton, Peter E.; Wehner, Michael; Williams, Dean N.

    2013-01-01

    Climate science is employing increasingly complex models and simulations to analyze the past and predict the future of Earth s climate. This growth in complexity is creating a widening gap between the data being produced and the ability to analyze the datasets. Parallel computing tools are necessary to analyze, compare, and interpret the simulation data. The Parallel Climate Analysis Toolkit (ParCAT) provides basic tools to efficiently use parallel computing techniques to make analysis of these datasets manageable. The toolkit provides the ability to compute spatio-temporal means, differences between runs or differences between averages of runs, and histograms of the values in a data set. ParCAT is implemented as a command-line utility written in C. This allows for easy integration in other tools and allows for use in scripts. This also makes it possible to run ParCAT on many platforms from laptops to supercomputers. ParCAT outputs NetCDF files so it is compatible with existing utilities such as Panoply and UV-CDAT. This paper describes ParCAT and presents results from some example runs on the Titan system at ORNL.

  10. ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation.

    PubMed

    Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta; Jakimowicz, Dagmara

    2016-04-01

    In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

  11. ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

    PubMed Central

    Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta

    2016-01-01

    In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

  12. Differential uPAR recruitment in caveolar-lipid rafts by GM1 and GM3 gangliosides regulates endothelial progenitor cells angiogenesis.

    PubMed

    Margheri, Francesca; Papucci, Laura; Schiavone, Nicola; D'Agostino, Riccardo; Trigari, Silvana; Serratì, Simona; Laurenzana, Anna; Biagioni, Alessio; Luciani, Cristina; Chillà, Anastasia; Andreucci, Elena; Del Rosso, Tommaso; Margheri, Giancarlo; Del Rosso, Mario; Fibbi, Gabriella

    2015-01-01

    Gangliosides and the urokinase plasminogen activator receptor (uPAR) tipically partition in specialized membrane microdomains called lipid-rafts. uPAR becomes functionally important in fostering angiogenesis in endothelial progenitor cells (EPCs) upon recruitment in caveolar-lipid rafts. Moreover, cell membrane enrichment with exogenous GM1 ganglioside is pro-angiogenic and opposite to the activity of GM3 ganglioside. On these basis, we first checked the interaction of uPAR with membrane models enriched with GM1 or GM3, relying on the adoption of solid-supported mobile bilayer lipid membranes with raft-like composition formed onto solid hydrophilic surfaces, and evaluated by surface plasmon resonance (SPR) the extent of uPAR recruitment. We estimated the apparent dissociation constants of uPAR-GM1/GM3 complexes. These preliminary observations, indicating that uPAR binds preferentially to GM1-enriched biomimetic membranes, were validated by identifying a pro-angiogenic activity of GM1-enriched EPCs, based on GM1-dependent uPAR recruitment in caveolar rafts. We have observed that addition of GM1 to EPCs culture medium promotes matrigel invasion and capillary morphogenesis, as opposed to the anti-angiogenesis activity of GM3. Moreover, GM1 also stimulates MAPKinases signalling pathways, typically associated with an angiogenesis program. Caveolar-raft isolation and Western blotting of uPAR showed that GM1 promotes caveolar-raft partitioning of uPAR, as opposed to control and GM3-challenged EPCs. By confocal microscopy, we have shown that in EPCs uPAR is present on the surface in at least three compartments, respectively, associated to GM1, GM3 and caveolar rafts. Following GM1 exogenous addition, the GM3 compartment is depleted of uPAR which is recruited within caveolar rafts thereby triggering angiogenesis. PMID:25313007

  13. Differential uPAR recruitment in caveolar-lipid rafts by GM1 and GM3 gangliosides regulates endothelial progenitor cells angiogenesis

    PubMed Central

    Margheri, Francesca; Papucci, Laura; Schiavone, Nicola; D'Agostino, Riccardo; Trigari, Silvana; Serratì, Simona; Laurenzana, Anna; Biagioni, Alessio; Luciani, Cristina; Chillà, Anastasia; Andreucci, Elena; Del Rosso, Tommaso; Margheri, Giancarlo; Del Rosso, Mario; Fibbi, Gabriella

    2015-01-01

    Gangliosides and the urokinase plasminogen activator receptor (uPAR) tipically partition in specialized membrane microdomains called lipid-rafts. uPAR becomes functionally important in fostering angiogenesis in endothelial progenitor cells (EPCs) upon recruitment in caveolar-lipid rafts. Moreover, cell membrane enrichment with exogenous GM1 ganglioside is pro-angiogenic and opposite to the activity of GM3 ganglioside. On these basis, we first checked the interaction of uPAR with membrane models enriched with GM1 or GM3, relying on the adoption of solid-supported mobile bilayer lipid membranes with raft-like composition formed onto solid hydrophilic surfaces, and evaluated by surface plasmon resonance (SPR) the extent of uPAR recruitment. We estimated the apparent dissociation constants of uPAR-GM1/GM3 complexes. These preliminary observations, indicating that uPAR binds preferentially to GM1-enriched biomimetic membranes, were validated by identifying a pro-angiogenic activity of GM1-enriched EPCs, based on GM1-dependent uPAR recruitment in caveolar rafts. We have observed that addition of GM1 to EPCs culture medium promotes matrigel invasion and capillary morphogenesis, as opposed to the anti-angiogenesis activity of GM3. Moreover, GM1 also stimulates MAPKinases signalling pathways, typically associated with an angiogenesis program. Caveolar-raft isolation and Western blotting of uPAR showed that GM1 promotes caveolar-raft partitioning of uPAR, as opposed to control and GM3-challenged EPCs. By confocal microscopy, we have shown that in EPCs uPAR is present on the surface in at least three compartments, respectively, associated to GM1, GM3 and caveolar rafts. Following GM1 exogenous addition, the GM3 compartment is depleted of uPAR which is recruited within caveolar rafts thereby triggering angiogenesis. PMID:25313007

  14. suPAR and Team Nephrology

    PubMed Central

    2014-01-01

    Primary focal segmental glomerulosclerosis (FSGS) accounts for nearly 10 % of patients who require renal replacement therapy. Elevated circulating levels of soluble urokinase receptor (suPAR) have been identified as a biomarker to discriminate primary FSGS from other glomerulopathies. Subsequent reports have questioned the diagnostic utility of this test. In a study in BMC Medicine, Huang et al. demonstrate that urinary soluble urokinase receptor (suPAR) excretion assists in distinguishing primary FSGS from other glomerular diseases, and that high plasma suPAR concentrations are not directly linked to a decline in glomerular filtration rate (GFR). This observation suggests that further investigation of suPAR is warranted in patients with FSGS. It should be interpreted in light of a recent report that B7-1 is expressed in the podocytes of a subset of patients with FSGS, and that blocking this molecule may represent the first successful targeted intervention for this disease. These advances highlight the rapid pace of scientific progress in the field of nephrology. Nephrologists should work together, share resources, and expedite the design of protocols to evaluate these novel biomarkers in a comprehensive and scientifically valid manner. Please see related article http://www.biomedcentral.com/1741-7015/12/81. PMID:24885021

  15. suPAR and Team Nephrology.

    PubMed

    Trachtman, Howard

    2014-01-01

    Primary focal segmental glomerulosclerosis (FSGS) accounts for nearly 10 % of patients who require renal replacement therapy. Elevated circulating levels of soluble urokinase receptor (suPAR) have been identified as a biomarker to discriminate primary FSGS from other glomerulopathies. Subsequent reports have questioned the diagnostic utility of this test. In a study in BMC Medicine, Huang et al. demonstrate that urinary soluble urokinase receptor (suPAR) excretion assists in distinguishing primary FSGS from other glomerular diseases, and that high plasma suPAR concentrations are not directly linked to a decline in glomerular filtration rate (GFR). This observation suggests that further investigation of suPAR is warranted in patients with FSGS. It should be interpreted in light of a recent report that B7-1 is expressed in the podocytes of a subset of patients with FSGS, and that blocking this molecule may represent the first successful targeted intervention for this disease. These advances highlight the rapid pace of scientific progress in the field of nephrology. Nephrologists should work together, share resources, and expedite the design of protocols to evaluate these novel biomarkers in a comprehensive and scientifically valid manner. PMID:24885021

  16. View from west to east of PAR site resident engineer's ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from west to east of PAR site resident engineer's office building (REOB) - Stanley R. Mickelsen Safeguard Complex, Resident Engineers Office Building, Southeast of intersection of PAR Access Road & Fourth Avenue, Nekoma, Cavalier County, ND

  17. View from east to west of PAR site storage building; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from east to west of PAR site storage building; formerly PAR dispensary - Stanley R. Mickelsen Safeguard Complex, Storage Building, Across street from Family Housing Units 110 & 111, Nekoma, Cavalier County, ND

  18. A Combined Global and Local Approach to Elucidate Spatial Organization of the Mycobacterial ParB-parS Partition Assembly

    SciTech Connect

    B Chaudhuri; S Gupta; V Urban; M Chance; R DMello; L Smith; K Lyons; J Gee

    2011-12-31

    Combining diverse sets of data at global (size, shape) and local (residue) scales is an emerging trend for elucidating the organization and function of the cellular assemblies. We used such a strategy, combining data from X-ray and neutron scattering with H/D-contrast variation and X-ray footprinting with mass spectrometry, to elucidate the spatial organization of the ParB-parS assembly from Mycobacterium tuberculosis. The ParB-parS participates in plasmid and chromosome segregation and condensation in predivisional bacterial cells. ParB polymerizes around the parS centromere(s) to form a higher-order assembly that serves to recruit cyto-skeletal ParA ATPases and SMC proteins for chromosome segregation. A hybrid model of the ParB-parS was built by combining and correlating computational models with experiment-derived information about size, shape, position of the symmetry axis within the shape, internal topology, DNA-protein interface, exposed surface patches, and prior knowledge. This first view of the ParB-parS leads us to propose how ParB spread on the chromosome to form a larger assembly.

  19. A Combined Global and Local Approach to Elucidate Spatial Organization of the Mycobacterial ParB-parS Partition

    SciTech Connect

    Chaudhuri, Barnali; Gupta, Sayan; Urban, Volker S; Chance, Mark; D'Mello, Rhijuta; Smith, Lauren; Lyons, Kelly; Gee, Jessica

    2010-01-01

    Combining diverse sets of data at global (size, shape) and local (residue) scales is an emerging trend for elucidating the organization and function of the cellular assemblies. We used such a strategy, combining data from X-ray and neutron scattering with H/D-contrast variation and X-ray footprinting with mass spectrometry, to elucidate the spatial organization of the ParB-parS assembly from Mycobacterium tuberculosis. The ParB-parS participates in plasmid and chromosome segregation and condensation in predivisional bacterial cells. ParB polymerizes around the parS centromere(s) to form a higher-order assembly that serves to recruit cyto-skeletal ParA ATPases and SMC proteins for chromosome segregation. A hybrid model of the ParB-parS was built by combining and correlating computational models with experiment-derived information about size, shape, position of the symmetry axis within the shape, internal topology, DNA-protein interface, exposed surface patches, and prior knowledge. This first view of the ParB-parS leads us to propose how ParB spread on the chromosome to form a larger assembly.

  20. Optical resonator

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    The invention discloses a semi-ring Fabry-Perot (SRFP) optical resonator structure comprising a medium including an edge forming a reflective facet and a waveguide within the medium, the waveguide having opposing ends formed by the reflective facet. The performance of the SRFP resonator can be further enhanced by including a Mach-Zehnder interferometer in the waveguide on one side of the gain medium. The optical resonator can be employed in a variety of optical devices. Laser structures using at least one SRFP resonator are disclosed where the resonators are disposed on opposite sides of a gain medium. Other laser structures employing one or more resonators on one side of a gain region are also disclosed.

  1. Resonance scraping

    SciTech Connect

    Collins, T.

    1986-06-01

    Protons lost in a ring leave at a few preferred locations, determined by some non-linear property of the dipoles. This paper suggests taking control of lost protons by beating the magnets at their own game - by means of a designed resonance used as a beam scraper. It is a study of suitable resonances, including estimates of the required multipole element strengths. The appropriate resonances are two-dimensional. A large number of figures is included.

  2. Lens implant surgery in pars planitis.

    PubMed

    Michelson, J B; Friedlaender, M H; Nozik, R A

    1990-08-01

    Intraocular lens (IOL) implantation is usually contraindicated in eyes with active inflammation, but patients with "burned-out" pars planitis also may be considered as candidates. Fifteen of 16 eyes in eight patients underwent extracapsular cataract extraction (ECCE) with posterior chamber IOL (PC IOL) implantation combined with pars plana vitrectomy for both cataracts and chronic cystoid macular edema (CME); 60% achieved visual acuity of 20/40 or better. Even with "low-grade" inflammation in these patients, however, a persistent veil of debris accumulated over the posterior and anterior surface of the IOL. One patient (patient 2) required 27 YAG procedures for two eyes, and another required 11 YAG procedures and eventual removal of the IOL. Another patient required surgical "brushing-off" of the IOL and vitrectomy. Even in eyes with "burned-out" uveitis, a continual low-grade inflammation may complicate the use of IOL implantation. PMID:2402411

  3. Par Pond refill water quality sampling

    SciTech Connect

    Koch, J.W. II; Martin, F.D.; Westbury, H.M.

    1996-08-01

    This study was designed to document anoxia and its cause in the event that the anoxia caused a fish kill. However, no fish kill was observed during this study, and dissolved oxygen and nutrient concentrations generally remained within the range expected for southeastern reservoirs. Par Pond water quality monitoring will continue during the second summer after refill as the aquatic macrophytes become reestablished and nutrients in the sediments are released to the water column.

  4. Combined DSEK and Transconjunctival Pars Plana Vitrectomy

    PubMed Central

    Sane, Mona; Shaikh, Naazli

    2016-01-01

    We report here three patients who underwent combined Descemet's stripping with endothelial keratoplasty and transconjunctival pars plana vitrectomy for bullous keratopathy and posterior segment pathology. A surgical technique and case histories are described. Anatomic and visual outcomes of combined Descemet's stripping with endothelial keratoplasty and vitrectomy were excellent. Our experience provides technical guidelines and limitations. The combined minimally invasive techniques allow for rapid anatomical recovery and return of function and visual acuity in a single sitting. PMID:27413563

  5. Mechanisms of apoptosis by the tumor suppressor Par-4.

    PubMed

    Hebbar, Nikhil; Wang, Chi; Rangnekar, Vivek M

    2012-12-01

    Par-4 is a pro-apoptotic, tumor suppressor protein that induces apoptosis selectively in cancer cells. Endoplasmic reticulum-stress and higher levels of protein kinase A in tumor cells confer the coveted feature of cancer selective response to extracellular and intracellular Par-4, respectively. Recent studies have shown that systemic Par-4 confers resistance to tumor growth in mice, and that tumor-resistance is transferable by bone-marrow transplantation. Moreover, recombinant Par-4 inhibits the growth of tumors in mice. As systemic Par-4 induces apoptosis via cell surface GRP78, strategies that promote GRP78 trafficking to the cell surface are expected sensitize cancer cells to circulating levels of Par-4. This review illustrates the domains and mechanisms by which Par-4 orchestrates the apoptotic process in both cell culture models and in physiological settings. PMID:22552839

  6. A Single parS Sequence from the Cluster of Four Sites Closest to oriC Is Necessary and Sufficient for Proper Chromosome Segregation in Pseudomonas aeruginosa

    PubMed Central

    Jecz, Paulina; Bartosik, Aneta A.; Glabski, Krzysztof; Jagura-Burdzy, Grazyna

    2015-01-01

    Among the mechanisms that control chromosome segregation in bacteria are highly-conserved partitioning systems comprising three components: ParA protein (a deviant Walker-type ATPase), ParB protein (a DNA-binding element) and multiple cis-acting palindromic centromere-like sequences, designated parS. Ten putative parS sites have been identified in the P. aeruginosa PAO1 genome, four localized in close proximity of oriC and six, diverged by more than one nucleotide from a perfect palindromic sequence, dispersed along the chromosome. Here, we constructed and analyzed P. aeruginosa mutants deprived of each single parS sequence and their different combinations. The analysis included evaluation of a set of phenotypic features, chromosome segregation, and ParB localization in the cells. It was found that ParB binds specifically to all ten parS sites, although with different affinities. The P. aeruginosa parS mutant with all ten parS sites modified (parSnull) is viable however it demonstrates the phenotype characteristic for parAnull or parBnull mutants: slightly slower growth rate, high frequency of anucleate cells, and defects in motility. The genomic position and sequence of parS determine its role in P. aeruginosa biology. It transpired that any one of the four parS sites proximal to oriC (parS1 to parS4), which are bound by ParB with the highest affinity, is necessary and sufficient for the parABS role in chromosome partitioning. When all these four sites are mutated simultaneously, the strain shows the parSnull phenotype, which indicates that none of the remaining six parS sites can substitute for these four oriC-proximal sites in this function. A single ectopic parS2 (inserted opposite oriC in the parSnull mutant) facilitates ParB organization into regularly spaced condensed foci and reverses some of the mutant phenotypes but is not sufficient for accurate chromosome segregation. PMID:25794281

  7. Escherichia coli low-copy-number plasmid R1 centromere parC forms a U-shaped complex with its binding protein ParR

    PubMed Central

    Hoischen, C.; Bussiek, M.; Langowski, J.; Diekmann, S.

    2008-01-01

    The Escherichia coli low-copy-number plasmid R1 contains a segregation machinery composed of parC, ParR and parM. The R1 centromere-like site parC contains two separate sets of repeats. By atomic force microscopy (AFM) we show here that ParR molecules bind to each of the 5-fold repeated iterons separately with the intervening sequence unbound by ParR. The two ParR protein complexes on parC do not complex with each other. ParR binds with a stoichiometry of about one ParR dimer per each single iteron. The measured DNA fragment lengths agreed with B-form DNA and each of the two parC 5-fold interon DNA stretches adopts a linear path in its complex with ParR. However, the overall parC/ParR complex with both iteron repeats bound by ParR forms an overall U-shaped structure: the DNA folds back on itself nearly completely, including an angle of ∼150°. Analysing linear DNA fragments, we never observed dimerized ParR complexes on one parC DNA molecule (intramolecular) nor a dimerization between ParR complexes bound to two different parC DNA molecules (intermolecular). This bacterial segrosome is compared to other bacterial segregation complexes. We speculate that partition complexes might have a similar overall structural organization and, at least in part, common functional properties. PMID:18056157

  8. Modelisation par elements finis du muscle strie

    NASA Astrophysics Data System (ADS)

    Leonard, Mathieu

    Ce present projet de recherche a permis. de creer un modele par elements finis du muscle strie humain dans le but d'etudier les mecanismes engendrant les lesions musculaires traumatiques. Ce modele constitue une plate-forme numerique capable de discerner l'influence des proprietes mecaniques des fascias et de la cellule musculaire sur le comportement dynamique du muscle lors d'une contraction excentrique, notamment le module de Young et le module de cisaillement de la couche de tissu conjonctif, l'orientation des fibres de collagene de cette membrane et le coefficient de poisson du muscle. La caracterisation experimentale in vitro de ces parametres pour des vitesses de deformation elevees a partir de muscles stries humains actifs est essentielle pour l'etude de lesions musculaires traumatiques. Le modele numerique developpe est capable de modeliser la contraction musculaire comme une transition de phase de la cellule musculaire par un changement de raideur et de volume a l'aide des lois de comportement de materiau predefinies dans le logiciel LS-DYNA (v971, Livermore Software Technology Corporation, Livermore, CA, USA). Le present projet de recherche introduit donc un phenomene physiologique qui pourrait expliquer des blessures musculaires courantes (crampes, courbatures, claquages, etc.), mais aussi des maladies ou desordres touchant le tissu conjonctif comme les collagenoses et la dystrophie musculaire. La predominance de blessures musculaires lors de contractions excentriques est egalement exposee. Le modele developpe dans ce projet de recherche met ainsi a l'avant-scene le concept de transition de phase ouvrant la porte au developpement de nouvelles technologies pour l'activation musculaire chez les personnes atteintes de paraplegie ou de muscles artificiels compacts pour l'elaboration de protheses ou d'exosquelettes. Mots-cles Muscle strie, lesion musculaire, fascia, contraction excentrique, modele par elements finis, transition de phase

  9. Evaluation of the PAR corneal topography system

    NASA Astrophysics Data System (ADS)

    Jindal, Prateek; Cheung, Susan; Pirouzian, Amir; Keates, Richard H.; Ren, Qiushi

    1995-05-01

    The purpose of this study was to evaluate the raster photogrammetry based Corneal Topography System by determining: inter-operator variability, reproducibility of images, effects of defocused and decentered images, and the precision of data at different optical zones. 4 human cadaver eyes were used to study the inter-operator variability. To study the reproducibility of images, 3 human cadaver eyes and a test surface doped with flourescine (provided by PAR Vision Systems Corporation) were focused and their images taken four successive times. Defocused and decentered images were taken of 4 human cadaver eyes and four times of the test surface mentioned above. The precision of defocused/decentered cadaver eyes was evaluated at the following optical zones: 3 mm, 4 mm, 5 mm, and 6 mm. All human cadaver eyes used in the above experiments had their epithelial layer removed before imaging. Average inter-operator variability was 0.06 D. In reproducibility attempts, there was an average deviation of 0.28 D for the human cadaver eyes and 0.04 D for the test surface. The defocused and decentered test surface gave an average deviation of 0.09 D. Defocused and decentered cadaver eyes resulted in an average deviation of 0.52 D, 0.37 D, 0.24 D, and 0.22 D at optical zones of 3 mm, 4 mm, 5 mm, and 6 mm, respectively. The imaging method employed by PAR Vision Systems Corporation virtually eliminates inter-operator variability. The PAR Corneal Topography System's clinical usefulness, however, could be improved by improving the reproducibility of images, decreasing the sensitivity to spatial alignment, and increasing accuracy over smaller optical zones.

  10. A conserved mode of protein recognition and binding in a ParD-ParE toxin-antitoxin complex†

    PubMed Central

    Dalton, Kevin M.; Crosson, Sean

    2010-01-01

    Toxin-antitoxin (TA) systems form a ubiquitous class of prokaryotic proteins with functional roles in plasmid inheritance, environmental stress response, and cell development. ParDE-family TA systems are broadly conserved on plasmids and bacterial chromosomes, and have been well characterized as genetic elements that promote stable plasmid inheritance. We present a crystal structure of a chromosomally-encoded ParD-ParE complex from Caulobacter crescentus at 2.6 Å resolution. This TA system forms an α2β2 heterotetramer in the crystal and in solution. The toxin-antitoxin binding interface reveals extensive polar and hydrophobic contacts of ParD antitoxin helices with a conserved recognition and binding groove on the ParE toxin. A cross-species comparison of this complex structure with related toxin structures identified an antitoxin recognition and binding sub-domain that is conserved between distantly-related members of the RelE/ParE toxin superfamily despite low overall primary sequence identity. We further demonstrate that ParD antitoxin is dimeric, stably folded, and largely helical when not bound to ParE toxin. Thus, the paradigmatic model in which antitoxin undergoes a disorder-to-order transition upon toxin binding does not apply to this chromosomal ParD-ParE TA system. PMID:20143871

  11. A Conserved Mode of Protein Recognition and Binding in a ParD−ParE Toxin−Antitoxin Complex

    SciTech Connect

    Dalton, Kevin M.; Crosson, Sean

    2010-05-06

    Toxin-antitoxin (TA) systems form a ubiquitous class of prokaryotic proteins with functional roles in plasmid inheritance, environmental stress response, and cell development. ParDE family TA systems are broadly conserved on plasmids and bacterial chromosomes and have been well characterized as genetic elements that promote stable plasmid inheritance. We present a crystal structure of a chromosomally encoded ParD-ParE complex from Caulobacter crescentus at 2.6 {angstrom} resolution. This TA system forms an {alpha}{sub 2}{beta}{sub 2} heterotetramer in the crystal and in solution. The toxin-antitoxin binding interface reveals extensive polar and hydrophobic contacts of ParD antitoxin helices with a conserved recognition and binding groove on the ParE toxin. A cross-species comparison of this complex structure with related toxin structures identified an antitoxin recognition and binding subdomain that is conserved between distantly related members of the RelE/ParE toxin superfamily despite a low level of overall primary sequence identity. We further demonstrate that ParD antitoxin is dimeric, stably folded, and largely helical when not bound to ParE toxin. Thus, the paradigmatic model in which antitoxin undergoes a disorder-to-order transition upon toxin binding does not apply to this chromosomal ParD-ParE TA system.

  12. Historic macrophyte development in Par Pond

    SciTech Connect

    Grace, J.B.

    1985-08-01

    Aerial photographs from 1975, 1980, and 1983 were examined to evaluate the changes that have occurred in the wetland vegetation of Par Pond, a reactor-cooling reservoir. Evaluation of the aerial photographs was based on comparisons with ground-level vegetation maps made during July 1984. Comparisons of photographs from August and December of 1983 revealed the main seasonal change in the aerial coverage of wetland vegetation to be the wintertime loss of non-persistent emergent species such as Nelumbo lutea and Nymphaea odorata. Comparisons between September 1980 and August 1983 revealed that the lakeward extent of non-persistent macrophytes has increased by an average of 8.2 m, though not all sites have changed equally. For persistent macrophytes (principally Typha), the average increase in lakeward extent between December 1975 and August 1983 was 3.48 m. The extensive development of wetland vegetation in Par Pond as well as the substantial spread of vegetation over only a few years time indicates the high suitability of this habitat for the growth of wetland plants.

  13. Une alternative au cobalt pour la synthese de nanotubes de carbone monoparoi par plasma inductif thermique

    NASA Astrophysics Data System (ADS)

    Carrier, Jean-Francois

    synthese de C-SWNT. Le produit final est par la suite recolte sur des filtres metalliques poreux, une fois le systeme mis a l'arret. Dans un premier temps, une analyse thermodynamique, calculee avec le logiciel Fact-Sage, a permis de mettre en lumiere l'etat des differentes produits et reactifs, tout au long de leur passage dans le systeme. Elle a permis de reveler la similitude de composition de la phase liquide du melange catalytique ternaire de base, avec celui du melange binaire, avec nickel et oxyde d'yttrium. Par la suite, une analyse du bilan d'energie, a l'aide d'un systeme d'acquisition de donnees, a permis de determiner que les conditions operatoires des cinq echantillons mis a l'essai etaient similaires. Au total, le produit final a ete caracterise a l'aide de six methodes de caracterisations differentes : l'analyse thermogravimetrique, la diffraction de rayons X, la microscopie electronique a balayage a haute resolution (HRSEM), la microscopie electronique a transmission (MET), la spectroscopie RAMAN, ainsi que la mesure de la surface specifique (BET). Les resultats de ces analyses ont permis de constater, de facon coherente, que le melange a base de molybdene etait celui qui produisait la moins bonne qualite de produit. Ensuite, en ordre croissant, s'en suivait du melange a base de MnO2 et de ZrO2. Le melange de reference, a base de cobalt, est au deuxieme rang en matiere de qualite. La palme revient au melange binaire, dont la proportion est double en nickel. Les resultats de ce travail de recherche permettent d'affirmer qu'il existe une alternative performante au cobalt pour effectuer la synthese de nanotubes de carbone monoparoi, par plasma inductif thermique. Cette alternative est l'utilisation d'un melange catalytique binaire a base de nickel et d'oxyde d'yttrium. Il est suggere que les performances plus faibles des recettes alternatives, moins performantes, pourraient etre expliquees par le profil thermique fixe du reacteur. Ceci pourrait favoriser

  14. A Par-1-Par-3-Centrosome Cell Polarity Pathway and Its Tuning for Isotropic Cell Adhesion.

    PubMed

    Jiang, Tao; McKinley, R F Andrew; McGill, Melanie A; Angers, Stephane; Harris, Tony J C

    2015-10-19

    To form regulated barriers between body compartments, epithelial cells polarize into apical and basolateral domains and assemble adherens junctions (AJs). Despite close links with polarity networks that generate single polarized domains, AJs distribute isotropically around the cell circumference for adhesion with all neighboring cells [1-3]. How AJs avoid the influence of polarity networks to maintain their isotropy has been unclear. In established epithelia, trans cadherin interactions could maintain AJ isotropy [4], but AJs are dynamic during epithelial development and remodeling [5, 6], and thus specific mechanisms may control their isotropy. In Drosophila, aPKC prevents hyper-polarization of junctions as epithelia develop from cellularization to gastrulation [7]. Here, we show that aPKC does so by inhibiting a positive feedback loop between Bazooka (Baz)/Par-3, a junctional organizer [5, 8-10], and centrosomes. Without aPKC, Baz and centrosomes lose their isotropic distributions and recruit each other to single plasma membrane (PM) domains. Surprisingly, our loss- and gain-of-function analyses show that the Baz-centrosome positive feedback loop is driven by Par-1, a kinase known to phosphorylate Baz and inhibit its basolateral localization [8, 11, 12]. We find that Par-1 promotes the positive feedback loop through both centrosome microtubule effects and Baz phosphorylation. Normally, aPKC attenuates the circuit by expelling Par-1 from the apical domain at gastrulation. The combination of local activation and global inhibition is a common polarization strategy [13-16]. Par-1 seems to couple both effects for a potent Baz polarization mechanism that is regulated for the isotropy of Baz and AJs around the cell circumference. PMID:26455305

  15. 2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. HI PAR (ACQUISITION RADAR) TOWER AND ENLISTED MEN (EM) BARRACKS WITH RADAR ATTACHED. - Nike Hercules Missile Battery Summit Site, Battery Control Administration & Barracks Building, Anchorage, Anchorage, AK

  16. Discrete resonances

    NASA Astrophysics Data System (ADS)

    Vivaldi, Franco

    2015-12-01

    The concept of resonance has been instrumental to the study of Hamiltonian systems with divided phase space. One can also define such systems over discrete spaces, which have a finite or countable number of points, but in this new setting the notion of resonance must be re-considered from scratch. I review some recent developments in the area of arithmetic dynamics which outline some salient features of linear and nonlinear stable (elliptic) orbits over a discrete space, and also underline the difficulties that emerge in their analysis.

  17. Discrete resonances

    NASA Astrophysics Data System (ADS)

    Vivaldi, Franco

    The concept of resonance has been instrumental to the study of Hamiltonian systems with divided phase space. One can also define such systems over discrete spaces, which have a finite or countable number of points, but in this new setting the notion of resonance must be re-considered from scratch. I review some recent developments in the area of arithmetic dynamics which outline some salient features of linear and nonlinear stable (elliptic) orbits over a discrete space, and also underline the difficulties that emerge in their analysis.

  18. Laser Resonator

    NASA Technical Reports Server (NTRS)

    Harper, L. L. (Inventor)

    1983-01-01

    An optical resonator cavity configuration has a unitary mirror with oppositely directed convex and concave reflective surfaces disposed into one fold and concertedly reversing both ends of a beam propagating from a laser rod disposed between two total internal reflection prisms. The optical components are rigidly positioned with perpendicularly crossed virtual rooflines by a compact optical bed. The rooflines of the internal reflection prisms, are arranged perpendicularly to the axis of the laser beam and to the optical axes of the optical resonator components.

  19. Transcriptome profiling reveals links between ParS/ParR, MexEF-OprN, and quorum sensing in the regulation of adaptation and virulence in Pseudomonas aeruginosa

    PubMed Central

    2013-01-01

    Background The ParS/ParR two component regulatory system plays critical roles for multidrug resistance in Pseudomonas aeruginosa. It was demonstrated that in the presence of antimicrobials, ParR enhances bacterial survival by distinct mechanisms including activation of the mexXY efflux genes, enhancement of lipopolysaccharide modification through the arn operon, and reduction of the expression of oprD porin. Results In this study, we report on transcriptomic analyses of P. aeruginosa PAO1 wild type and parS and parR mutants growing in a defined minimal medium. Our transcriptomic analysis provides the first estimates of transcript abundance for the 5570 coding genes in P. aeruginosa PAO1. Comparative transcriptomics of P. aeruginosa PAO1 and par mutants identified a total of 464 genes regulated by ParS and ParR. Results also showed that mutations in the parS/parR system abolished expression of the mexEF-oprN operon by down-regulating the regulatory gene mexS. In addition to the known effects on drug resistance genes, transcript abundances of the quorum sensing genes (rhlIR and pqsABCDE-phnAB) were higher in both parS and parR mutants. In accordance with these results, a significant portion of the ParS/ParR regulated genes belonged to the MexEF-OprN and quorum sensing regulons. Deletion of the par genes also led to increased phenazine production and swarming motility, consistent with the up-regulation of the phenazine and rhamnolipid biosynthetic genes, respectively. Conclusion Our results link the ParS/ParR two component signal transduction system to MexEF-OprN and quorum sensing systems in P. aeruginosa. These results expand our understanding of the roles of the ParS/ParR system in the regulation of gene expression in P. aeruginosa, especially in the absence of antimicrobials. PMID:24034668

  20. Mars Aerocapture Analysis For MESUR/Mars-Pathfinder Aeroshells Using Un-modulated Control in Low L/D Configurations

    NASA Technical Reports Server (NTRS)

    Wercinski, Paul F.; Edwards, Thomas A. (Technical Monitor)

    1994-01-01

    Aerocapture scenarios are examined to determine the feasibility of using MESUR/Mars Pathfinder aeroshell designs to capture spacecraft aerodynamically into Mars orbit. Using lift over drag (L/D) ratios up to 0.3, entry trajectories were simulated over a range of entry vehicle masses and entry velocities. Entry corridor widths were calculated for undershoot and overshoot trajectories yielding Mars parking orbits having periods from 2 to 20 hours. For entries with L/D = 0.3, entry corridor widths of about 1.2 degrees are possible over entry velocities from 5.5 to 9.0 km/sec. The design constraints for an aeroshell used for orbital aerocapture are less severe than a ballistic entry for a surface lander mission such as Mars Pathfinder, because the aerothermodynamic heating and deceleration loads are smaller. The mass savings from aerocapture orbit insertion versus propulsive insertion into Mars orbit could result in significantly reducing program costs and increasing mission capabilities.

  1. Taare Zameen Par and dyslexic savants.

    PubMed

    Chakravarty, Ambar

    2009-04-01

    The film Taare Zameen Par (Stars upon the Ground) portrays the tormented life at school and at home of a child with dyslexia and his eventual success after his artistic talents are discovered by his art teacher at the boarding school. The film hints at a curious neurocognitive phenomenon of creativity in the midst of language disability, as exemplified in the lives of people like Leonardo da Vinci and Albert Einstein, both of whom demonstrated extraordinary creativity even though they were probably affected with developmental learning disorders. It has been hypothesized that a developmental delay in the dominant hemisphere most likely 'disinhibits' the nondominant parietal lobe, unmasking talents-artistic or otherwise-in some such individuals. It has been suggested that, in remedial training, children with learning disorders be encouraged to develop such hidden talents to full capacity, rather than be subjected to the usual overemphasis on the correction of the disturbed coded symbol operations. PMID:20142854

  2. Taare Zameen Par and dyslexic savants

    PubMed Central

    Chakravarty, Ambar

    2009-01-01

    The film Taare Zameen Par (Stars upon the Ground) portrays the tormented life at school and at home of a child with dyslexia and his eventual success after his artistic talents are discovered by his art teacher at the boarding school. The film hints at a curious neurocognitive phenomenon of creativity in the midst of language disability, as exemplified in the lives of people like Leonardo da Vinci and Albert Einstein, both of whom demonstrated extraordinary creativity even though they were probably affected with developmental learning disorders. It has been hypothesized that a developmental delay in the dominant hemisphere most likely ‘disinhibits’ the nondominant parietal lobe, unmasking talents—artistic or otherwise—in some such individuals. It has been suggested that, in remedial training, children with learning disorders be encouraged to develop such hidden talents to full capacity, rather than be subjected to the usual overemphasis on the correction of the disturbed coded symbol operations. PMID:20142854

  3. Biased signaling: potential agonist and antagonist of PAR2.

    PubMed

    Kakarala, Kavita Kumari; Jamil, Kaiser

    2016-06-01

    Protease activated receptor 2 (PAR2) has emerged as one of the promising therapeutic targets to inhibit rapidly metastasizing breast cancer cells. However, its elusive molecular mechanism of activation and signaling has made it a difficult target for drug development. In this study, in silico methods were used to unfold PAR2 molecular mechanism of signaling based on the concept of GPCR receptor plasticity. Although, there are no conclusive evidences of the presence of specific endogenous ligands for PAR2, the efficacy of synthetic agonist and antagonist in PAR2 signaling has opened up the possibilities of ligand-mediated signaling. Furthermore, it has been proved that ligands specific for one GPCR can induce signaling in GPCRs belonging to other subfamilies. Therefore, the aim of this study was to identify potential agonists and antagonists from the GPCR ligand library (GLL), which may induce biased signaling in PAR2 using the concept of existence of multiple ligand-stabilized receptor conformations. The results of our in silico study suggest that PAR2 may show biased signaling mainly with agonists of serotonin type 1, β-adrenergic type 1,3 and antagonists of substance K (NK1), serotonin type 2, dopamine type 4, and thromboxane receptors. Further, this study also throws light on the putative ligand-specific conformations of PAR2. Thus, the results of this study provide structural insights to putative conformations of PAR2 and also gives initial clues to medicinal chemists for rational drug design targeting this challenging receptor. PMID:26295578

  4. Proteases in agricultural dust induce lung inflammation through PAR-1 and PAR-2 activation.

    PubMed

    Romberger, Debra J; Heires, Art J; Nordgren, Tara M; Souder, Chelsea P; West, William; Liu, Xiang-de; Poole, Jill A; Toews, Myron L; Wyatt, Todd A

    2015-08-15

    Workers exposed to aerosolized dust present in concentrated animal feeding operations (CAFOs) are susceptible to inflammatory lung diseases, such as chronic obstructive pulmonary disease. Extracts of dust collected from hog CAFOs [hog dust extract (HDE)] are potent stimulators of lung inflammatory responses in several model systems. The observation that HDE contains active proteases prompted the present study, which evaluated the role of CAFO dust proteases in lung inflammatory processes and tested whether protease-activated receptors (PARs) are involved in the signaling pathway for these events. We hypothesized that the damaging proinflammatory effect of HDE is due, in part, to the proteolytic activation of PARs, and inhibiting the proteases in HDE or disrupting PAR activation would attenuate HDE-mediated inflammatory indexes in bronchial epithelial cells (BECs), in mouse lung slices in vitro, and in a murine in vivo exposure model. Human BECs and mouse lung slice cultures stimulated with 5% HDE released significantly more of each of the cytokines measured (IL-6, IL-8, TNF-α, keratinocyte-derived chemokine/CXC chemokine ligand 1, and macrophage inflammatory protein-2/CXC chemokine ligand 2) than controls, and these effects were markedly diminished by protease inhibition. Inhibition of PARs also blunted the HDE-induced cytokine release from BECs. In addition, protease depletion inhibited HDE-induced BEC intracellular PKCα and PKCε activation. C57BL/6J mice administered 12.5% HDE intranasally, either once or daily for 3 wk, exhibited increased total cellular and neutrophil influx, bronchial alveolar fluid inflammatory cytokines, lung histopathology, and inflammatory scores compared with mice receiving protease-depleted HDE. These data suggest that proteases in dust from CAFOs are important mediators of lung inflammation, and these proteases and their receptors may provide novel targets for therapeutic intervention in CAFO dust-induced airways disease. PMID

  5. Cancer-selective apoptosis by tumor suppressor par-4.

    PubMed

    Hebbar, Nikhil; Shrestha-Bhattarai, Tripti; Rangnekar, Vivek M

    2014-01-01

    Tumor suppressor genes play an important role in preventing neoplastic transformation and maintaining normal tissue homeostasis. Par-4 is one such tumor suppressor which is unique in its ability to selectively induce apoptosis in cancer cells while leaving the normal cells unaffected. The cancer cell specific activity of Par-4 is elicited through intracellular as well as extracellular mechanisms. Intracellularly Par-4 acts through the inhibition of pro-survival pathways and activation of Fas mediated apoptosis whereas extracellular (secreted Par-4) acts by binding to cell surface GRP78 leading to activation of the extrinsic apoptotic pathway. Many studies have highlighted the importance of Par-4 not only in preventing cancer development/recurrence but also as a promising anticancer therapeutic agent. PMID:25001535

  6. PAR-3 and PAR-1 Inhibit LET-99 Localization to Generate a Cortical Band Important for Spindle Positioning in Caenorhabditis elegans Embryos

    PubMed Central

    Wu, Jui-Ching

    2007-01-01

    The conserved PAR proteins are localized in asymmetric cortical domains and are required for the polarized localization of cell fate determinants in many organisms. In Caenorhabditis elegans embryos, LET-99 and G protein signaling act downstream of the PARs to regulate spindle positioning and ensure asymmetric division. PAR-3 and PAR-2 localize LET-99 to a posterior cortical band through an unknown mechanism. Here we report that LET-99 asymmetry depends on cortically localized PAR-1 and PAR-4 but not on cytoplasmic polarity effectors. In par-1 and par-4 embryos, LET-99 accumulates at the entire posterior cortex, but remains at low levels at the anterior cortex occupied by PAR-3. Further, PAR-3 and PAR-1 have graded cortical distributions with the highest levels at the anterior and posterior poles, respectively, and the lowest levels of these proteins correlate with high LET-99 accumulation. These results suggest that PAR-3 and PAR-1 inhibit the localization of LET-99 to generate a band pattern. In addition, PAR-1 kinase activity is required for the inhibition of LET-99 localization, and PAR-1 associates with LET-99. Finally, examination of par-1 embryos suggests that the banded pattern of LET-99 is critical for normal posterior spindle displacement and to prevent spindle misorientation caused by cell shape constraints. PMID:17761536

  7. Recombination in the Human Pseudoautosomal Region PAR1

    PubMed Central

    Hinch, Anjali G.; Altemose, Nicolas; Noor, Nudrat; Donnelly, Peter; Myers, Simon R.

    2014-01-01

    The pseudoautosomal region (PAR) is a short region of homology between the mammalian X and Y chromosomes, which has undergone rapid evolution. A crossover in the PAR is essential for the proper disjunction of X and Y chromosomes in male meiosis, and PAR deletion results in male sterility. This leads the human PAR with the obligatory crossover, PAR1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. However, the mechanism by which this obligatory crossover occurs remains unknown, as does the fine-scale positioning of crossovers across this region. Recent research in mice has suggested that crossovers in PAR may be mediated independently of the protein PRDM9, which localises virtually all crossovers in the autosomes. To investigate recombination in this region, we construct the most fine-scale genetic map containing directly observed crossovers to date using African-American pedigrees. We leverage recombination rates inferred from the breakdown of linkage disequilibrium in human populations and investigate the signatures of DNA evolution due to recombination. Further, we identify direct PRDM9 binding sites using ChIP-seq in human cells. Using these independent lines of evidence, we show that, in contrast with mouse, PRDM9 does localise peaks of recombination in the human PAR1. We find that recombination is a far more rapid and intense driver of sequence evolution in PAR1 than it is on the autosomes. We also show that PAR1 hotspot activities differ significantly among human populations. Finally, we find evidence that PAR1 hotspot positions have changed between human and chimpanzee, with no evidence of sharing among the hottest hotspots. We anticipate that the genetic maps built and validated in this work will aid research on this vital and fascinating region of the genome. PMID:25033397

  8. Circulating suPAR in Two Cohorts of Primary FSGS

    PubMed Central

    Wei, Changli; Trachtman, Howard; Li, Jing; Dong, Chuanhui; Friedman, Aaron L.; Gassman, Jennifer J.; McMahan, June L.; Radeva, Milena; Heil, Karsten M.; Trautmann, Agnes; Anarat, Ali; Emre, Sevinc; Ghiggeri, Gian M.; Ozaltin, Fatih; Haffner, Dieter; Gipson, Debbie S.; Kaskel, Frederick; Fischer, Dagmar-Christiane; Schaefer, Franz

    2012-01-01

    Overexpression of soluble urokinase receptor (suPAR) causes pathology in animal models similar to primary FSGS, and one recent study demonstrated elevated levels of serum suPAR in patients with the disease. Here, we analyzed circulating suPAR levels in two cohorts of children and adults with biopsy-proven primary FSGS: 70 patients from the North America–based FSGS clinical trial (CT) and 94 patients from PodoNet, the Europe-based consortium studying steroid-resistant nephrotic syndrome. Circulating suPAR levels were elevated in 84.3% and 55.3% of patients with FSGS patients in the CT and PodoNet cohorts, respectively, compared with 6% of controls (P<0.0001); inflammation did not account for this difference. Multiple regression analysis suggested that lower suPAR levels associated with higher estimated GFR, male sex, and treatment with mycophenolate mofetil. In the CT cohort, there was a positive association between the relative reduction of suPAR after 26 weeks of treatment and reduction of proteinuria, with higher odds for complete remission (P=0.04). In the PodoNet cohort, patients with an NPHS2 mutation had higher suPAR levels than those without a mutation. In conclusion, suPAR levels are elevated in geographically and ethnically diverse patients with FSGS and do not reflect a nonspecific proinflammatory milieu. The associations between a change in circulating suPAR with different therapeutic regimens and with remission support the role of suPAR in the pathogenesis of FSGS. PMID:23138488

  9. Circulating suPAR in two cohorts of primary FSGS.

    PubMed

    Wei, Changli; Trachtman, Howard; Li, Jing; Dong, Chuanhui; Friedman, Aaron L; Gassman, Jennifer J; McMahan, June L; Radeva, Milena; Heil, Karsten M; Trautmann, Agnes; Anarat, Ali; Emre, Sevinc; Ghiggeri, Gian M; Ozaltin, Fatih; Haffner, Dieter; Gipson, Debbie S; Kaskel, Frederick; Fischer, Dagmar-Christiane; Schaefer, Franz; Reiser, Jochen

    2012-12-01

    Overexpression of soluble urokinase receptor (suPAR) causes pathology in animal models similar to primary FSGS, and one recent study demonstrated elevated levels of serum suPAR in patients with the disease. Here, we analyzed circulating suPAR levels in two cohorts of children and adults with biopsy-proven primary FSGS: 70 patients from the North America-based FSGS clinical trial (CT) and 94 patients from PodoNet, the Europe-based consortium studying steroid-resistant nephrotic syndrome. Circulating suPAR levels were elevated in 84.3% and 55.3% of patients with FSGS patients in the CT and PodoNet cohorts, respectively, compared with 6% of controls (P<0.0001); inflammation did not account for this difference. Multiple regression analysis suggested that lower suPAR levels associated with higher estimated GFR, male sex, and treatment with mycophenolate mofetil. In the CT cohort, there was a positive association between the relative reduction of suPAR after 26 weeks of treatment and reduction of proteinuria, with higher odds for complete remission (P=0.04). In the PodoNet cohort, patients with an NPHS2 mutation had higher suPAR levels than those without a mutation. In conclusion, suPAR levels are elevated in geographically and ethnically diverse patients with FSGS and do not reflect a nonspecific proinflammatory milieu. The associations between a change in circulating suPAR with different therapeutic regimens and with remission support the role of suPAR in the pathogenesis of FSGS. PMID:23138488

  10. Recombination in the human Pseudoautosomal region PAR1.

    PubMed

    Hinch, Anjali G; Altemose, Nicolas; Noor, Nudrat; Donnelly, Peter; Myers, Simon R

    2014-07-01

    The pseudoautosomal region (PAR) is a short region of homology between the mammalian X and Y chromosomes, which has undergone rapid evolution. A crossover in the PAR is essential for the proper disjunction of X and Y chromosomes in male meiosis, and PAR deletion results in male sterility. This leads the human PAR with the obligatory crossover, PAR1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. However, the mechanism by which this obligatory crossover occurs remains unknown, as does the fine-scale positioning of crossovers across this region. Recent research in mice has suggested that crossovers in PAR may be mediated independently of the protein PRDM9, which localises virtually all crossovers in the autosomes. To investigate recombination in this region, we construct the most fine-scale genetic map containing directly observed crossovers to date using African-American pedigrees. We leverage recombination rates inferred from the breakdown of linkage disequilibrium in human populations and investigate the signatures of DNA evolution due to recombination. Further, we identify direct PRDM9 binding sites using ChIP-seq in human cells. Using these independent lines of evidence, we show that, in contrast with mouse, PRDM9 does localise peaks of recombination in the human PAR1. We find that recombination is a far more rapid and intense driver of sequence evolution in PAR1 than it is on the autosomes. We also show that PAR1 hotspot activities differ significantly among human populations. Finally, we find evidence that PAR1 hotspot positions have changed between human and chimpanzee, with no evidence of sharing among the hottest hotspots. We anticipate that the genetic maps built and validated in this work will aid research on this vital and fascinating region of the genome. PMID:25033397

  11. Condensation and localization of the partitioning protein ParB on the bacterial chromosome.

    PubMed

    Broedersz, Chase P; Wang, Xindan; Meir, Yigal; Loparo, Joseph J; Rudner, David Z; Wingreen, Ned S

    2014-06-17

    The ParABS system mediates chromosome segregation and plasmid partitioning in many bacteria. As part of the partitioning mechanism, ParB proteins form a nucleoprotein complex at parS sites. The biophysical basis underlying ParB-DNA complex formation and localization remains elusive. Specifically, it is unclear whether ParB spreads in 1D along DNA or assembles into a 3D protein-DNA complex. We show that a combination of 1D spreading bonds and a single 3D bridging bond between ParB proteins constitutes a minimal model for a condensed ParB-DNA complex. This model implies a scaling behavior for ParB-mediated silencing of parS-flanking genes, which we confirm to be satisfied by experimental data from P1 plasmids. Furthermore, this model is consistent with experiments on the effects of DNA roadblocks on ParB localization. Finally, we show experimentally that a single parS site is necessary and sufficient for ParB-DNA complex formation in vivo. Together with our model, this suggests that ParB binding to parS triggers a conformational switch in ParB that overcomes a nucleation barrier. Conceptually, the combination of spreading and bridging bonds in our model provides a surface tension ensuring the condensation of the ParB-DNA complex, with analogies to liquid-like compartments such as nucleoli in eukaryotes. PMID:24927534

  12. SPRY1 promotes the degradation of uPAR and inhibits uPAR-mediated cell adhesion and proliferation

    PubMed Central

    Liu, Xiufeng; Lan, Yan; Zhang, Di; Wang, Kai; Wang, Yao; Hua, Zi-Chun

    2014-01-01

    Urokinase plasminogen activator receptor (uPAR) is a GPI anchored cell surface protein that is closely associated with invasion, migration, and metastasis of cancer cells. Many functional extracellular proteins and transmembrane receptors interact with uPAR. However, few studies have examined the association of uPAR with cytoplasm proteins. We previously used yeast two-hybrid screening to isolate several novel uPAR-interacting cytoplasmic proteins, including Sprouty1 (SPRY1), an inhibitor of the (Ras-mitogen-activated protein kinase) MAPK pathway. In this study, we show that SPRY1 interacts with uPAR and directs it toward lysosomal-mediated degradation. Overexpression of SPRY1 decreased the cell surface and cytoplasmic uPAR protein level. Moreover, SPRY1 overexpression augmented uPAR-induced cell adhesion to vitronectin as well as proliferation of cancer cells. Our results also further support the critical role of SPRY1 contribution to tumor growth. In a subcutaneous tumor model, overexpression of SPRY1 in HCT116 or A549 xenograft in athymic nude mice led to great suppression of tumor growth. These results show that SPRY1 may affect tumor cell function through direct interaction with uPAR and promote its lysosomal degradation. PMID:25520860

  13. Resonant behavior of dielectric objects (electrostatic resonances).

    PubMed

    Fredkin, D R; Mayergoyz, I D

    2003-12-19

    Resonant behavior of dielectric objects occurs at certain frequencies for which the object permittivity is negative and the free-space wavelength is large in comparison with the object dimensions. Unique physical features of these resonances are studied and a novel technique for the calculation of resonance values of permittivity, and hence resonance frequencies, is proposed. Scale invariance of resonance frequencies, unusually strong orthogonality properties of resonance modes, and a two-dimensional phenomenon of "twin" spectra are reported. The paper concludes with brief discussions of optical controllability of these resonances in semiconductor nanoparticles and a plausible, electrostatic resonance based, mechanism for nucleation and formation of ball lightning. PMID:14754117

  14. Traitement des fractures des plateaux externes par vissage percutané assisté par arthroscopie

    PubMed Central

    Abouchane, Merouane; Belmoubarik, Amine; Benameur, Hamza; Haddoun, Ahmed Reda; Nechad, Mohammed

    2015-01-01

    Le but de notre étude est d'évaluer les résultats de fractures des plateaux tibiaux externes traitées par ostéosynthèse percutanée assistée par arthroscopie. Dix patients (8 hommes et 2 femmes) de 32 ans en moyenne ont subi cette intervention afin de réparer des fractures des plateaux tibiaux Schatzker I-III. Après avoir appliqué un garrot pneumatique, nous avons réduit et fixé la fracture au moyen de vis cannelées souschondrales. Lésions associées retrouvent deux lésions partielles du ménisque externe ont été retrouvé, traitées par résection partielle. Une orthèse de genou été de mise à but antalgique et protectrice pendant six semaines avec béquillage et interdiction de l'appui pour une durée de douze semaines avec reprise d'appui partiel au delà. La durée d'hospitalisation été d'une moyenne de cinq jours. La rééducation passive a été commence le lendemain de l'intervention et continuait dans chez un kinésithérapeute à la sortie du patient du service. Le suivi été à J7, J15, 1mois, 3mois, 6 mois puis tous les 6 mois. Neuf de nos patients ont été revu régulièrement sauf un perdu de vue. Le recul moyen de notre série été de 16 mois (10 et 24 mois). Le score de Lysholm a été utilisé pour évaluer les résultats cliniques chez nos neuf patients: excellent chez trois patients bons chez trois moyen chez un seul et mauvais chez deux patients. Tous nos neuf patients ont consolidé (figure 10 contrôle scopique d un article). Aucune gonarthrose n'a été note chez nos neuf patients due essentiellement au recul moyen faible de 16 mois. Le traitement des fractures des plateaux tibiaux externes assisté par arthroscopie produit des résultats satisfaisants et peut être accepté comme solution de rechange efficace au traitement des fractures des plateaux tibiaux causées par un choc de faible énergie. PMID:26587137

  15. Rôle de l'hydrogène dans le procédé de purification du silicium par plasma thermique inductif

    NASA Astrophysics Data System (ADS)

    Erin, J.; Morvan, D.; Amouroux, J.

    1993-03-01

    The use of the thermal process for purification of silicon led to a material with the chemical purity required for phototovoltaic applications. In this paper, the various properties of ArH2 plasma mixtures are briefly reviewed and the effect of hydrogen percentage in an argon plasma used for melting and purifying silicon is pointed out. Physico-chemical analysis of the purified silicon showed that hydrogen diffused in the material and could passivate crystal defects by formation of stable chemical bonds such as Si-H. La technique de purification du silicium sous plasma thermique permet d'aboutir à un matériau de pureté chimique requise pour l'industrie photovoltaïque. Dans ce travail, nous soulignerons le rôle de l'hydrogène intervenant dans les propriétés du plasma en rappelant les caractéristiques des plasmas Ar-H2 utilisés pour fondre et purifier le silicium. Les caractéristiques physico-chimiques du silicium purifié montrent que l'hydrogène diffuse dans le matériau et est en mesure de cicatriser les défauts cristallins par formation de liaisons chimiques stables de type Si-H.

  16. Rétention de sels simples par une membrane chargée d'ultrafiltration à base d'alumine gamma

    NASA Astrophysics Data System (ADS)

    Benalla, R.; Persin, M.; Toreis, N.; Sarrazin, J.; Larbot, A.; Bouhaouss, A.

    1999-09-01

    Filtration of different electrolytes solutions was performed by means of a γ alumina ultrafiltration membrane. The experimental determination of the rejection rate for the salts leads to their phenomenologic parameters σ and P. The observed rejection are in agreement with a Donnan mechanism of exclusion of the coion outside of the membrane pore. Une membrane d'ultrafiltration en alumine γ a été utilisée pour la filtration de différentes solutions salines. Les rétentions des différents sels ont été d'abord mesurées à l'aide de cette membrane puis les coefficients de réflexion σ et les perméabilités P pour chaque sel ont été déterminées. La rétention des sels peut être expliquée par un mécanisme d'exclusion de type Donnan.

  17. Control of cleavage spindle orientation in Caenorhabditis elegans: The role of the genes par-2 and par-3

    SciTech Connect

    Cheng, N.N.; Kirby, C.M.; Kemphues, K.J.

    1995-02-01

    Polarized asymmetric divisions play important roles in the development of plants and animals. The first two embryonic cleavages of Caenorhabditis elegans provide an opportunity to study the mechanisms controlling polarized asymmetric divisions. The first cleavage is unequal, producing daughters with different sizes and fates. The daughter blastomeres divide with different orientations at the second cleavage; the anterior blastomere divides equally across the long axis of the egg, whereas the posterior blastomere divides unequally along the long axis. We report here the results of our analysis of the genes par-2 and par-3 with respect to their contribution to the polarity of these divisions. Strong loss-of-function mutations in both genes lead to an equal first cleavage and an altered second cleavage. Interestingly, the mutations exhibit striking gene-specific differences at the second cleavage. The par-2 mutations lead to transverse spindle orientations in both blastomeres, whereas par-3 mutations lead to longitudinal spindle orientations in both blastomeres. The spindle orientation defects correlate with defects in centrosome movements during both the first and the second cell cycle. Temperature shift experiments with par-2 (it5ts) indicate that the par-2(+) activity is not required after the two-cell stage. Analysis of double mutants shows that par-3 is epistatic to par-2. We propose a model wherein par-2(+) and par-3(+) act in concert during the first cell cycle to affect asymmetric modification of the cytoskeleton. This polar modification leads to different behaviors of centrosomes in the anterior and posterior and leads ultimately to blastomere-specific spindle orientations at the second cleavage. 44 refs., 5 figs., 5 tabs.

  18. Poly(ADP-ribose) (PAR) polymer is a death signal

    PubMed Central

    Andrabi, Shaida A.; Kim, No Soo; Yu, Seong-Woon; Wang, Hongmin; Koh, David W.; Sasaki, Masayuki; Klaus, Judith A.; Otsuka, Takashi; Zhang, Zhizheng; Koehler, Raymond C.; Hurn, Patricia D.; Poirier, Guy G.; Dawson, Valina L.; Dawson, Ted M.

    2006-01-01

    Excessive activation of the nuclear enzyme, poly(ADP-ribose) polymerase-1 (PARP-1) plays a prominent role in various of models of cellular injury. Here, we identify poly(ADP-ribose) (PAR) polymer, a product of PARP-1 activity, as a previously uncharacterized cell death signal. PAR polymer is directly toxic to neurons, and degradation of PAR polymer by poly(ADP-ribose) glycohydrolase (PARG) or phosphodiesterase 1 prevents PAR polymer-induced cell death. PARP-1-dependent, NMDA excitotoxicity of cortical neurons is reduced by neutralizing antibodies to PAR and by overexpression of PARG. Neuronal cultures with reduced levels of PARG are more sensitive to NMDA excitotoxicity than WT cultures. Transgenic mice overexpressing PARG have significantly reduced infarct volumes after focal ischemia. Conversely, mice with reduced levels of PARG have significantly increased infarct volumes after focal ischemia compared with WT littermate controls. These results reveal PAR polymer as a signaling molecule that induces cell death and suggests that interference with PAR polymer signaling may offer innovative therapeutic approaches for the treatment of cellular injury. PMID:17116882

  19. Intercomparison of Nine National High-vacuum Standards under the Auspices of the Bureau International des Poids et Mesures

    NASA Astrophysics Data System (ADS)

    Messer, G.; Jitschin, W.; Rubet, L.; Calcatelli, A.; Redgrave, F. J.; Keprt, A.; Wei-nan, Fei; Sharma, J. K. N.; Dittmann, S.; Ono, M.

    1989-01-01

    The Bureau International des Poids et Mesures has initiated world-wide intercomparisons of pressure standards. The intercomparison in the regime of very low pressures, i.e. 10-4 to 1 Pa, using Ar as the test gas, has now been completed with the participation of laboratories in nine countries (in alphabetical order): Czechoslovakia, Federal Republic of Germany, France, India, Italy, Japan, People's Republic of China, UK and United States of America. In addition, five of these laboratories made measurements using H2 as the test gas. Four spinning-rotor gauges were employed as transfer standards. The achieved transfer uncertainty between the pilot laboratory (Physikalisch-Technische Bundesanstalt) and a participating laboratory lies between 0.16% and 0.30% (1σ) for Ar and has allowed an intercomparison at this level of accuracy. At all investigated pressures the standards in the various laboratories lie within an interval of +/-3% around the standard of the pilot laboratory. For a brief synopsis of the intercomparison results, the calibration data of each laboratory for one gas species are reduced to a single number, i.e., the average over the pressure range 10-3 to 1 Pa, although this procedure is somewhat arbitrary and obscures scatter and pressure-dependence of some calibration results. These averages deviate from their mean by not more than about 1%. Systematic deviations between some laboratories are clearly identifiable: however, for most of the laboratories it appears that these are compatible with the estimated uncertainties of the pressure generation and the transfer uncertainty.

  20. Multi-scale photoacoustic remote sensing (PARS) (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Haji Reza, Parsin; Bell, Kevan; Shi, W.; Zemp, Roger J.

    2016-03-01

    We introduce a novel multi-scale photoacoustic remote sensing (PARS) imaging system. Our system can provide optical resolution details for superficial structures as well as acoustic resolution for deep-tissue imaging down to 5 cm, in a non-contact setting. PARS system does not require any contact with the sample or ultrasound coupling medium. The optical resolution PARS (OR-OARS) system uses optically focused pulsed excitation with optical detection of photoacoustic signatures using a long-coherence interrogation beam co-focused and co-scanned with the excitation spot. In the OR-PARS initial pressures are sampled right at their subsurface origin where acoustic pressures are largest. The Acoustic resolution PARS (AR-PARS) picks up the surface oscillation of the tissue caused by generated photoacoustic signal using a modified version of Michelson interferometry. By taking advantage of 4-meters polarization maintaining single-mode fiber and a green fiber laser we have generated a multi-wavelength source using stimulated Raman scattering. Remote functional imaging using this multi-wavelength excitation source and PARS detection mechanism has been demonstrated. The oxygen saturation estimations are shown for both phantom and in vivo studies. Images of blood vessel structures for an In vivo chicken embryo model is demonstrated. The Phantom studies indicates ~3µm and ~300µm lateral resolution for OR-PARS and AR-PARS respectively. To the best of our knowledge this is the first dual modality non-contact optical and acoustic resolution system used for in vivo imaging.

  1. Novel Role for Proteinase-activated Receptor 2 (PAR2) in Membrane Trafficking of Proteinase-activated Receptor 4 (PAR4)*

    PubMed Central

    Cunningham, Margaret R.; McIntosh, Kathryn A.; Pediani, John D.; Robben, Joris; Cooke, Alexandra E.; Nilsson, Mary; Gould, Gwyn W.; Mundell, Stuart; Milligan, Graeme; Plevin, Robin

    2012-01-01

    Proteinase-activated receptors 4 (PAR4) is a class A G protein-coupled receptor (GPCR) recognized through the ability of serine proteases such as thrombin and trypsin to mediate receptor activation. Due to the irreversible nature of activation, a fresh supply of receptor is required to be mobilized to the cell surface for responsiveness to agonist to be sustained. Unlike other PAR subtypes, the mechanisms regulating receptor trafficking of PAR4 remain unknown. Here, we report novel features of the intracellular trafficking of PAR4 to the plasma membrane. PAR4 was poorly expressed at the plasma membrane and largely retained in the endoplasmic reticulum (ER) in a complex with the COPI protein subunit β-COP1. Analysis of the PAR4 protein sequence identified an arginine-based (RXR) ER retention sequence located within intracellular loop-2 (R183AR → A183AA), mutation of which allowed efficient membrane delivery of PAR4. Interestingly, co-expression with PAR2 facilitated plasma membrane delivery of PAR4, an effect produced through disruption of β-COP1 binding and facilitation of interaction with the chaperone protein 14-3-3ζ. Intermolecular FRET studies confirmed heterodimerization between PAR2 and PAR4. PAR2 also enhanced glycosylation of PAR4 and activation of PAR4 signaling. Our results identify a novel regulatory role for PAR2 in the anterograde traffic of PAR4. PAR2 was shown to both facilitate and abrogate protein interactions with PAR4, impacting upon receptor localization and cell signal transduction. This work is likely to impact markedly upon the understanding of the receptor pharmacology of PAR4 in normal physiology and disease. PMID:22411985

  2. Novel role for proteinase-activated receptor 2 (PAR2) in membrane trafficking of proteinase-activated receptor 4 (PAR4).

    PubMed

    Cunningham, Margaret R; McIntosh, Kathryn A; Pediani, John D; Robben, Joris; Cooke, Alexandra E; Nilsson, Mary; Gould, Gwyn W; Mundell, Stuart; Milligan, Graeme; Plevin, Robin

    2012-05-11

    Proteinase-activated receptors 4 (PAR(4)) is a class A G protein-coupled receptor (GPCR) recognized through the ability of serine proteases such as thrombin and trypsin to mediate receptor activation. Due to the irreversible nature of activation, a fresh supply of receptor is required to be mobilized to the cell surface for responsiveness to agonist to be sustained. Unlike other PAR subtypes, the mechanisms regulating receptor trafficking of PAR(4) remain unknown. Here, we report novel features of the intracellular trafficking of PAR(4) to the plasma membrane. PAR(4) was poorly expressed at the plasma membrane and largely retained in the endoplasmic reticulum (ER) in a complex with the COPI protein subunit β-COP1. Analysis of the PAR(4) protein sequence identified an arginine-based (RXR) ER retention sequence located within intracellular loop-2 (R(183)AR → A(183)AA), mutation of which allowed efficient membrane delivery of PAR(4). Interestingly, co-expression with PAR(2) facilitated plasma membrane delivery of PAR(4), an effect produced through disruption of β-COP1 binding and facilitation of interaction with the chaperone protein 14-3-3ζ. Intermolecular FRET studies confirmed heterodimerization between PAR(2) and PAR(4). PAR(2) also enhanced glycosylation of PAR(4) and activation of PAR(4) signaling. Our results identify a novel regulatory role for PAR(2) in the anterograde traffic of PAR(4). PAR(2) was shown to both facilitate and abrogate protein interactions with PAR(4), impacting upon receptor localization and cell signal transduction. This work is likely to impact markedly upon the understanding of the receptor pharmacology of PAR(4) in normal physiology and disease. PMID:22411985

  3. Protease-Activated Receptor (PAR)2, but Not PAR1, Is Involved in Collateral Formation and Anti-Inflammatory Monocyte Polarization in a Mouse Hind Limb Ischemia Model

    PubMed Central

    Nossent, Anne Yael; van Oeveren-Rietdijk, Annemarie M.; de Vries, Margreet R.; Spek, C. Arnold; van Zonneveld, Anton Jan; Reitsma, Pieter H.; Hamming, Jaap F.; de Boer, Hetty C.; Versteeg, Henri H.; Quax, Paul H. A.

    2013-01-01

    Aims In collateral development (i.e. arteriogenesis), mononuclear cells are important and exist as a heterogeneous population consisting of pro-inflammatory and anti-inflammatory/repair-associated cells. Protease-activated receptor (PAR)1 and PAR2 are G-protein-coupled receptors that are both expressed by mononuclear cells and are involved in pro-inflammatory reactions, while PAR2 also plays a role in repair-associated responses. Here, we investigated the physiological role of PAR1 and PAR2 in arteriogenesis in a murine hind limb ischemia model. Methods and Results PAR1-deficient (PAR1-/-), PAR2-deficient (PAR2-/-) and wild-type (WT) mice underwent femoral artery ligation. Laser Doppler measurements revealed reduced post-ischemic blood flow recovery in PAR2-/- hind limbs when compared to WT, while PAR1-/- mice were not affected. Upon ischemia, reduced numbers of smooth muscle actin (SMA)-positive collaterals and CD31-positive capillaries were found in PAR2-/- mice when compared to WT mice, whereas these parameters in PAR1-/- mice did not differ from WT mice. The pool of circulating repair-associated (Ly6C-low) monocytes and the number of repair-associated (CD206-positive) macrophages surrounding collaterals in the hind limbs were increased in WT and PAR1-/- mice, but unaffected in PAR2-/- mice. The number of repair-associated macrophages in PAR2-/- hind limbs correlated with CD11b- and CD115-expression on the circulating monocytes in these animals, suggesting that monocyte extravasation and M-CSF-dependent differentiation into repair-associated cells are hampered. Conclusion PAR2, but not PAR1, is involved in arteriogenesis and promotes the repair-associated response in ischemic tissues. Therefore, PAR2 potentially forms a new pro-arteriogenic target in coronary artery disease (CAD) patients. PMID:23637930

  4. Participation of Chromosome Segregation Protein ParAI of Vibrio cholerae in Chromosome Replication▿ †

    PubMed Central

    Kadoya, Ryosuke; Baek, Jong Hwan; Sarker, Arnab; Chattoraj, Dhruba K.

    2011-01-01

    Vibrio cholerae carries homologs of plasmid-borne parA and parB genes on both of its chromosomes. The par genes help to segregate many plasmids and chromosomes. Here we have studied the par genes of V. cholerae chromosome I. Earlier studies suggested that ParBI binds to the centromeric site parSI near the origin of replication (oriI), and parSI-ParBI complexes are placed at the cell poles by ParAI. Deletion of parAI and parSI caused the origin-proximal DNA to be less polar. Here we found that deletion of parBI also resulted in a less polar localization of oriI. However, unlike the deletion of parAI, the deletion of parBI increased the oriI number. Replication was normal when both parAI and parBI were deleted, suggesting that ParBI mediates its action through ParAI. Overexpression of ParAI in a parABI-deleted strain also increased the DNA content. The results are similar to those found for Bacillus subtilis, where ParA (Soj) stimulates replication and this activity is repressed by ParB (SpoOJ). As in B. subtilis, the stimulation of replication most likely involves the replication initiator DnaA. Our results indicate that control of chromosomal DNA replication is an additional function of chromosomal par genes conserved across the Gram-positive/Gram-negative divide. PMID:21257772

  5. Predicted PAR1 inhibitors from multiple computational methods

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Liu, Jinfeng; Zhu, Tong; Zhang, Lujia; He, Xiao; Zhang, John Z. H.

    2016-08-01

    Multiple computational approaches are employed in order to find potentially strong binders of PAR1 from the two molecular databases: the Specs database containing more than 200,000 commercially available molecules and the traditional Chinese medicine (TCM) database. By combining the use of popular docking scoring functions together with detailed molecular dynamics simulation and protein-ligand free energy calculations, a total of fourteen molecules are found to be potentially strong binders of PAR1. The atomic details in protein-ligand interactions of these molecules with PAR1 are analyzed to help understand the binding mechanism which should be very useful in design of new drugs.

  6. If It's Resonance, What is Resonating?

    ERIC Educational Resources Information Center

    Kerber, Robert C.

    2006-01-01

    The phenomenon under the name "resonance," which, is based on the mathematical analogy between mechanical resonance and the behavior of wave functions in quantum mechanical exchange phenomena was described. The resonating system does not have a structure intermediate between those involved in the resonance, but instead a structure which is further…

  7. Conception et calibration d'un sonoreacteur pour l'oxydation de la cellulose par le systeme TEMPO/NaOCl/NaBr

    NASA Astrophysics Data System (ADS)

    Paquin, Michel

    grande consommation d'energie et de reactif qui rend le procede difficilement accessible au milieu industriel. L'utilisation des ultrasons lors de la reaction d'oxydation permet de reduire de 50% le temps de reaction et d'autant la consommation de produits chimiques. Actuellement le processus d'oxydation s'effectue en mode discontinu pour une quantite de 20 grammes de pate dans un reacteur en verre dans un bain a ultrason. L'objectif principal de ce travail est d'elaborer un sonoreacteur en mode semi-continu afin d'etre en mesure de transferer une reaction d'oxydation du mode discontinu en mode semi-continu. Le transfert de reaction sera effectue en realisant la calibration de l'activite acoustique des deux differents reacteurs, discontinu et semi-continu, par la methode de Weissler. La methode de Weissler quantifie le taux de production radicalaire en mesurant la formation d'iode moleculaire d'une solution aqueuse d'iodure de potassium sous ultrason. Suite a sa calibration, le sonoreacteur pilote (mode semi-continu) a demontre une augmentation de la production radicalaire de 683 % a 170 kHz en comparaison avec l'utilisation d'un bain a ultrason a la meme frequence. Lors de la reaction d'oxydation, la puissance optimale utilisee dans le bain a ultrason a 170 kHz est de 1000 W. La puissance utilisee selon les resultats de calibration obtenue dans le sonoreacteur pilote est de 125 W soit une diminution de l'energie appliquee de 87,5 %. Lors de la reaction d'oxydation, le taux de production des groupements carboxylates est de 2,6 mmol COOH kg/min dans le bain a ultrason et de 6,87 mmol COOH kg/min dans le sonoreacteur pilote soit une augmentation de 164% du taux de formation. Selon les resultats obtenus, l'utilisation d'un sonoreacteur en mode continu peut etre envisageable pour la reaction d'oxydation de la cellulose par le systeme TEMPO-NaOCl-NaBr en industrie au niveau industriel.

  8. PARS: Programs for Analysis and Resizing of Structures, user manual

    NASA Technical Reports Server (NTRS)

    Haftka, R. T.; Prasad, B.; Tsach, U.

    1979-01-01

    PARS processors and their use, flutter analysis, sensitivity analysis for stresses, and resizing are presented. Design variable definition and interface with finite element model, static constraints and their derivatives, flutter derivatives, and optimization are discussed.

  9. View from northeast to southwest of PAR site sentry station; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from northeast to southwest of PAR site sentry station; formerly the bachelor's enlisted men's quarter (BEQ) - Stanley R. Mickelsen Safeguard Complex, Sentry Station, North of Second Avenue & West of Electrical Switch Station No. 2, Nekoma, Cavalier County, ND

  10. View from southwest to northeast of PAR site fresh water ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from southwest to northeast of PAR site fresh water pump house - Stanley R. Mickelsen Safeguard Complex, Fresh Water Pump House, In Limited Access Area, on Patrol Road next to Open Storage Reservoir No. 736, Nekoma, Cavalier County, ND

  11. Protection des ions organiques contre les dommages induits a l'ADN par les electrons de basse energie

    NASA Astrophysics Data System (ADS)

    Dumont, Ariane

    'ADN de differentes epaisseurs, possedant entre 0 et 32 ions organiques/ nucleotide, ont ete irradies avec des electrons de 10eV. Les dommages induits par les electrons, sous forme de cassures, ont ete detectes par electrophorese. Nous avons demontre que le rendement de cassure simple brin diminuait de facon dramatique en fonction du nombre d'ions organiques/ nucleotide. Aussi peu que 2 ions organiques/ nucleotide sont suffisant pour decroitre le rendement de SSB de 70%. Cet effet radioprotecteur est en partie explique par l'augmentation de l'epaisseur des films, mais surtout par la modification du champ electrique a proximite de l'ADN, due a l'ajout de molecules chargees positivement. La modification du champ electrique pres de l'ADN altere les parametres de resonance comme le temps de vie de l'anion transitoire et la limite de dissociation, qui influent directement sur la section efficace d'attachement dissociatif. L'effet protecteur peut egalement etre explique par la restauration des bases anioniques deshydrogenees induites par l'attachement dissociatif de l'electron sur une base (G(-H)-). Ce sont les molecules Tris qui, en transferant un atome d'hydrogene ou un proton, restaurent les bases deshydrogenees et inhibent par le fait meme la formation de cassures simple brin. Ces resultats indiquent que les histones peuvent egalement participer a la reparation de dommages precoces induits a l'ADN avant qu'elles ne menent a des dommages encore plus nocifs et difficiles a reparer, comme les cassures simples brins. Mots cles : Electrons de basse energie, dommage a l'ADN, ions organiques, attachement dissociatif de l'electron.

  12. Caractérisation des effets de l'implantation ionique dans les alliages super-élastiques nickel titane par diffraction des rayons X

    NASA Astrophysics Data System (ADS)

    Pelletier, H.; Muller, D.; Grob, J. J.; Mille, P.; Cornet, A.

    2002-07-01

    the specific properties (shape memory effect and super-elasticity) of NiTi alloys have provided the enabling technology for many groundbreaking applications in the medical and dentistry industries. These applications include everything from the surgical tools to permanent implants. Super-elastic NiTi alloys take advantage of a stress induced martensitic transformation to achieve incredible amounts of flexibility. This last property represents the most interesting aspect of such alloys for restoration procedures. However, recent instrumentation tests have shown brittle rupture of endodontic instruments inside the tooth during preparation of dental root channels.To improve the mechanical properties of NiTi endodontic instruments, argon, nitrogen and boron implantations at different energies and at fixed dose (1.10^{17} at.cm^{-2}) have been used. In this paper, we have investigated the effects on NiTi microstructure, especially the crystalline to amorphous transition induced by ion bombardment, using Grazing Incidence X-ray Diffraction (GIXRD). Nano-indentation tests have also been performed to determine hardness H and elastic modulus E of implanted surfaces as a function of ion species and energy. Le but de cette d'étude est de caractériser les effets de l'implantation ionique sur la microstructure d'un alliage Nickel Titane à l'aide de la diffraction des rayons X en incidence rasante. Nous avons réalisé différents types d'implantation en faisant varier l'espèce implantée (bore, azote, argon) ainsi que l'énergie d'implantation, pour des doses d'implantation de l'ordre de 1.10^{17} at.cm^{-2}. Les résultats des mesures de diffraction sous différents angles d'incidence (0{,}5^circ leq α_ileq 6^circ) ont été corrélés avec les différents profils d'implantation simulés. Des tests de nanoindentation ainsi que des mesures de RBS ont été également réalisés. Après implantation, on observe la formation d'une couche amorphe, conduisant à une

  13. Par-4 secretion: stoichiometry of 3-arylquinoline binding to vimentin.

    PubMed

    Sviripa, Vitaliy M; Burikhanov, Ravshan; Obiero, Josiah M; Yuan, Yaxia; Nickell, Justin R; Dwoskin, Linda P; Zhan, Chang-Guo; Liu, Chunming; Tsodikov, Oleg V; Rangnekar, Vivek M; Watt, David S

    2016-01-01

    Advanced prostate tumors usually metastasize to the lung, bone, and other vital tissues and are resistant to conventional therapy. Prostate apoptosis response-4 protein (Par-4) is a tumor suppressor that causes apoptosis in therapy-resistant prostate cancer cells by binding specifically to a receptor, Glucose-regulated protein-78 (GRP78), found only on the surface of cancer cells. 3-Arylquinolines or "arylquins" induce normal cells to release Par-4 from the intermediate filament protein, vimentin and promote Par-4 secretion that targets cancer cells in a paracrine manner. A structure-activity study identified arylquins that promote Par-4 secretion, and an evaluation of arylquin binding to the hERG potassium ion channel using a [(3)H]-dofetilide binding assay permitted the identification of structural features that separated this undesired activity from the desired Par-4 secretory activity. A binding study that relied on the natural fluorescence of arylquins and that used the purified rod domain of vimentin (residues 99-411) suggested that the mechanism behind Par-4 release involved arylquin binding to multiple sites in the rod domain. PMID:26548370

  14. Croissance epitaxiale de GaAs sur substrats de Ge par epitaxie par faisceaux chimiques

    NASA Astrophysics Data System (ADS)

    Belanger, Simon

    La situation energetique et les enjeux environnementaux auxquels la societe est confrontee entrainent un interet grandissant pour la production d'electricite a partir de l'energie solaire. Parmi les technologies actuellement disponibles, la filiere du photovoltaique a concentrateur solaire (CPV pour concentrator photovoltaics) possede un rendement superieur et mi potentiel interessant a condition que ses couts de production soient competitifs. La methode d'epitaxie par faisceaux chimiques (CBE pour chemical beam epitaxy) possede plusieurs caracteristiques qui la rendent interessante pour la production a grande echelle de cellules photovoltaiques a jonctions multiples a base de semi-conducteurs III-V. Ce type de cellule possede la meilleure efficacite atteinte a ce jour et est utilise sur les satellites et les systemes photovoltaiques a concentrateur solaire (CPV) les plus efficaces. Une des principales forces de la technique CBE se trouve dans son potentiel d'efficacite d'utilisation des materiaux source qui est superieur a celui de la technique d'epitaxie qui est couramment utilisee pour la production a grande echelle de ces cellules. Ce memoire de maitrise presente les travaux effectues dans le but d'evaluer le potentiel de la technique CBE pour realiser la croissance de couches de GaAs sur des substrats de Ge. Cette croissance constitue la premiere etape de fabrication de nombreux modeles de cellules solaires a haute performance decrites plus haut. La realisation de ce projet a necessite le developpement d'un procede de preparation de surface pour les substrats de germanium, la realisation de nombreuses sceances de croissance epitaxiale et la caracterisation des materiaux obtenus par microscopie optique, microscopie a force atomique (AFM), diffraction des rayons-X a haute resolution (HRXRD), microscopie electronique a transmission (TEM), photoluminescence a basse temperature (LTPL) et spectrometrie de masse des ions secondaires (SIMS). Les experiences ont permis

  15. Arthrose due au genu varum: traitement par osteotomie tibiale de valgisation

    PubMed Central

    Moussa, Abdou Kadri; Lukulunga, Loubet Unyendje; Mahfoud, Mustapha; El Bardouni, Ahmed; Ismail, Farid; Kharmaz, Mohamed; Berrada, Mohammed Saleh; El Yaacoubi, Moradh

    2014-01-01

    clichés nous ont permis de classer l'arthrose du genou selon Ahlbäck. 72,5% des patients, présentaient une arthrose débutante. Le pangonogramme a été réalisé pour mesurer la déviation axiale du génu varum. La déviation angulaire: HKA (angle entre le centre de la tête fémorale et le milieu de la cheville) préopératoire a varié entre 163° et 176°, soit une moyenne de 175,46°. Une correction moyenne de déviation de 11,3° a été réalisée avec des extrêmes de 7 à 19°. Cet angle de correction (DAC) qui variait de 7 à 19° a été supérieur à 15° dans 57,39%s inférieur à 15° chez 38%. 27,4% des patients avaient une déviation angulaire importante avec une arthrose avancée. Après un bilan préopératoire et une planification opératoire 73% des patients ont été opérés sous anesthésie loco-régionale. Pour l'ostéotomie tibiale de fermeture, la voie d'abord a été la voie de Gernez antérolatérale, utilisée chez 56 cas (48,6%), l'ostéotomie tibiale d'ouverture (la voie d'abord était Gernez antéro-médiale) effectuée dans 20 cas (17,3%);et l'ostéotomie curviplane, a été réalisée par une voie d'abord longitudinale médiane dans 39%. Les ostéosynthèses ont été réalisées dans 51 cas (44,3%) par les agrafes de Blount, dans 54 cas (46,9%) par la plaque en T ou en L et dans 11 cas par une plaque en col de cygne. En per-opératoire nous avons enregistré deux (02) cas de fractures du plateau tibial médial, en post-opératoire on a eu 1 cas d'infection superficielle et comme complications tardives une raideur du genou (18,2%) et 3,4% de pseudarthrose, une récidive du génu varum dans 19,1% (n = 22) après 3 années de recul. Les résultats du traitement ont été bons dans 78,4% selon le score HSS. L'OTV sur genu varum a été réalisé chez des patients relativement âgés avec la prédominance du sexe féminin. Les techniques utilisées dépendaient de la préférence du chirurgien. Les résultats sont probants malgré la fr

  16. Problemes poses par la mesure du rendement en francais des eleves franco-ontariens (Problems Posed by the Measurement of Proficiency in French Among Franco-Ontarian Students). Working Papers on Bilingualism, No. 16.

    ERIC Educational Resources Information Center

    Canale, Michael; Mougeon, Raymond

    This study examines the hypothesis that the French used by a large number of Franco-Ontarians represents a linguistic system (or several systems) that differs from Standard French. In addition, a review of previous research leads to the inverse hypothesis, that Ontarian French represents a body of different systems or sub-systems that are more or…

  17. Appréciation de la sévérité de l'affection des patients admis en réanimation par la mesure de la CRP

    PubMed Central

    Djuma, Jackson; Kalenga, Prosper; Kazadi, Costa; Orbegozo, Diego; Vincent, Jean Louis

    2015-01-01

    Introduction La CRP est produite en grande quantité dans les processus inflammatoires aigus et chroniques. L'hypothèse de ce travail est que la CRP permet, à faible coût, d'apprécier la sévérité des patients admis en réanimation. Méthodes La valeur journalière du taux sérique de CRP a été corrélée aux scores APACHE II à l'admission et SOFA pris quotidiennement durant le séjour en réanimation. La population étudiée était constituée de 100 patients admis en réanimation aux cliniques universitaires de Bruxelles. Résultats Les patients septiques avaient un taux de CRP plus élevé comparé aux non septiques. Les patients ayant une CRP élevée avaient les scores APACHE (26 ± 6 vs 20 ± 9, p < 0,05), SOFA à l'admission (8 ± 4 vs 4 ± 3, p < 0.05), SOFA maximum plus élevés (9 ± 4 vs 7 ± 3 et 9 ± 4 vs 7 ± 3, p < 0.05) et un séjour en réanimation plus long. Les patients ayant un plus grand nombre d'organes défaillants ont la CRP la plus élevée (365 mg/L vs 80 mg/L, 205 mg/L vs 60 mg/L, 110 mg/L vs 60 mg/L, 150 mg/L vs 60 mg/L). Conclusion Chez les patients présentant un taux sérique de CRP élevé, les scores de gravité (APACHE et SOFA), le pourcentage de patients présentant une infection et la durée du séjour en réanimation sont plus élevés. PMID:26301005

  18. Pars Planitis: Epidemiology, Clinical Characteristics, Management and Visual Prognosis

    PubMed Central

    Ozdal, Pinar Cakar; Berker, Nilufer; Tugal-Tutkun, Ilknur

    2015-01-01

    Pars planitis is an idiopathic chronic intermediate uveitis which predominantly affects children and adolescents, and accounts for 5-26.7% of pediatric uveitis. Although an autoimmune process with a genetic predisposition has been suggested, its etiology still remains unknown. The most common presenting symptoms are floaters and blurred vision. Diffuse vitreous cells, haze, snowballs and snowbanks are typical findings of pars planitis. Peripheral retinal vasculitis, optic disc edema and anterior segment inflammation are other well-known findings. Although pars planitis is known to be a benign form of uveitis in most cases, it may become a potentially blinding disease due to complications including cataract, cystoid macular edema, vitreous opacities and optic disc edema. Cystoid macular edema is the most common cause of visual morbidity. Band keratopathy, epiretinal membrane formation, vitreous condensation, neovascularizations, vitreous hemorrhage, retinal detachment, cyclitic membranes, glaucoma and amblyopia may develop as a consequence of the chronic course of the disease. Exclusion of infectious and non-infectious causes which may present with intermediate uveitis is of utmost importance before starting treatment. Treatment of pars planitis has been a controversial issue. There is no consensus specifically for treatment of cases with minimal inflammation and relatively good visual acuity. However, current experience shows that pars planitis may cause severe inflammation and needs an aggressive treatment. A stepladder approach including corticosteroids, immunosupressive agents, anti-tumor necrosis factor-alpha and pars plana vitrectomy and/or laser photocoagulation is the most commonly used method for treatment of pars planitis. Adequate control of inflammation and prompt detection of associated complications are crucial in order to improve the overall prognosis of the disease. PMID:27051493

  19. Par Pond vegetation status Summer 1995 -- June survey descriptive summary

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1995-06-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the shoreline aquatic plant communities in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level, indicated that much of the original plant communities and the intermediate shoreline communities present on the exposed sediments have been lost. The extensive old-field and emergent marsh communities that were present on the exposed shoreline during the drawdown have been flooded and much of the pre-drawdown Par Pond aquatic plant communities have not had sufficient time for re-establishment. The shoreline does, however, have extensive beds of maidencane which extend from the shoreline margin to areas as deep as 2 and perhaps 3 meters. Scattered individual plants of lotus and watershield are common and may indicate likely directions of future wetland development in Par Pond. In addition, within isolated coves, which apparently received ground water seepage and/or stream surface flows during the period of the Par Pond draw down, extensive beds of waterlilies and spike rush are common. Invasion of willow and red maple occurred along the lake shoreline as well. Although not absent from this survey, evidence of the extensive redevelopment of the large cattail and eel grass beds was not observed in this first survey of Par Pond. Future surveys during the growing seasons of 1995, 1996, and 1997 along with the evaluation of satellite date to map the areal extent of the macrophyte beds of Par Pond are planned.

  20. Regenerative feedback resonant circuit

    DOEpatents

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  1. Combined pars plana vitrectomy-scleral buckle versus pars plana vitrectomy for proliferative vitreoretinopathy.

    PubMed

    Lai, Frank H P; Lo, Ernie C F; Chan, Vesta C K; Brelen, Mårten; Lo, Wai Ling; Young, Alvin L

    2016-04-01

    The purpose of the study is to evaluate the surgical outcomes of combined pars plana vitrectomy-scleral buckle (PPV-SB) versus pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy (PVR). One thousand one hundred and seventy four patients with rhegmatogenous retinal detachment surgery between January 2002 and December 2013 were retrospectively reviewed. Patients with grade C PVR treated with either combined PPV-SB or PPV alone were included in the study. Study outcomes included single surgery anatomic success rate and postoperative visual outcome at 12 months postoperatively. Seventy-seven patients with grade C PVR were identified for analysis. At the end of 12-month follow-up, 80.5 % eyes (33/41) in the PPV-SB group and 58.3 % eyes (21/36) in the PPV group achieved single surgery anatomical success. In a multiple logistic regression model, none of the baseline variables (age, gender, macula status, grade of PVR, extent of detachment, presence of vitreous hemorrhage, lens status, status of high myopia) nor types of retinal detachment surgery (use of scleral buckle, barrier endolaser, 360 degree endolaser, cryopexy, retinectomy, tamponade agent, phacoemulsification) had significant effect on single surgery anatomical success. The post-treatment mean logMAR visual acuity of the PPV-SB group was 1.58 ± 0.58 and the PPV group was 1.57 ± 0.61. There was no significant difference in the postoperative visual acuity between the two groups (P = 0.849). For patients with grade C PVR, PPV-SB did not demonstrate a superiority over PPV alone in achieving single surgery anatomical success. PMID:26260357

  2. Par Pond vegetation status Summer 1995 -- September survey descriptive summary

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1995-09-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the emergent shoreline aquatic plant communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level and continued with this mid-September survey. Communities similar to the pre-drawdown Par Pond aquatic plant communities are becoming re-established; especially, beds of maidencane, lotus, waterlily, and watershield are now extensive and well established. Cattail occurrence continues to increase, but large beds common to Par Pond prior to the drawdown have not formed. Future surveys during the late growing seasons of 1995, and throughout 1996 and 1997, along with the evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned.

  3. Par Pond vegetation status Summer 1995 -- October survey descriptive summary

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1995-11-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the emergent shoreline aquatic plant communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level and continued with this late October survey. Communities similar to the pre-drawdown Par Pond aquatic plant communities are becoming re-established; especially, beds of maiden cane, lotus, waterlily, and watershield are now extensive and well established. Cattail occurrence continues to increase, but large beds common to Par Pond prior to the drawdown have not formed. Future surveys throughout 1996 and 1997, along with the continued evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned.

  4. PAR-1 phosphorylates Mind bomb to promote vertebrate neurogenesis

    PubMed Central

    Ossipova, Olga; Ezan, Jerome; Sokol, Sergei Y.

    2010-01-01

    Summary Generation of neurons in the vertebrate central nervous system requires complex transcriptional regulatory network and signaling processes in polarized neuroepithelial progenitor cells. Here we demonstrate that neurogenesis in the Xenopus neural plate in vivo and mammalian neural progenitors in vitro involves intrinsic antagonistic activities of the polarity proteins PAR-1 and aPKC. Furthermore, we show that Mind bomb (Mib), a ubiquitin ligase that promotes Notch ligand trafficking and activity, is a crucial molecular substrate for PAR-1. The phosphorylation of Mib by PAR-1 results in Mib degradation, repression of Notch signaling and stimulation of neuronal differentiation. These observations suggest a conserved mechanism for neuronal fate determination that might operate during asymmetric divisions of polarized neural progenitor cells. PMID:19686683

  5. Application de l'A.D.L, pour la mesure du champ de vitesses instationnaires de llecoulement a Ilechappement d'un moteur a combustion interne

    NASA Astrophysics Data System (ADS)

    Boutrif, M. S.; Thelliez, M.

    1993-01-01

    We present experimental results of instantaneous velocity measurement, which were obtained by application of the laser Doppler anemometry (L.D.A.) at the exhaust pipe of a reciprocating engine under real working conditions. First of all, we show that the instantaneous velocity is monodimensional along a straight exhaust pipe, and that the boundary layer develops within a 2mm thickness. We also show that the cylinder discharges in two phases : the blow down period and the final part of exhaust stroke. We also make obvious, that the flow escapes very quickly : its velocity varies between - 100m/s and 200m/s within a period shorter than 1ms ; thereby, we do record the acoustic resonance phenomenon, when the engine speed is greater than 3 000rpm. Finally, we show that in the exhaust pipe the apparent fluctuation - i.e. the cyclic dispersion and the actual turbulence - may reach 15%. Nous présentons des résultats expérimentaux du champ de vitesses instationnaires, obtenus par adaptation et application de la vélocimétrie laser interférentielle communément appelée à effet Doppler (L.D.A.), à l'échappement d'un moteur altematif à combustion inteme en fonctionnement nominal. Tout d'abord, nous montrons que dans un tube d'échappement long et droit, la vitesse instantanée est bien monodimensionnelle et que l'écoulement occupe la quasitotalité de la section droite géométrique du tube (une couche limite d'épaisseur inférieure à 2mm se développe très près de la paroi du tube). Nous pouvons également décrire la vidange du cylindre du moteur étudié en deux phases principales : bouffée d'échappement et refoulement des gaz brûlés par le piston. Nous mettons de même en évidence l'état très pulsé de l'écoulement, puisqu'en un intervalle de temps inférieur à 1ms, la vitesse de l'écoulement varie de - 100m/s à 200m/s ; nous enregistrons ainsi l'apparition du phénomène de résonance acoustique à des vitesses de rotation supérieures à 3 500

  6. Bacterial actin: architecture of the ParMRC plasmid DNA partitioning complex.

    PubMed

    Salje, Jeanne; Löwe, Jan

    2008-08-20

    The R1 plasmid employs ATP-driven polymerisation of the actin-like protein ParM to move newly replicated DNA to opposite poles of a bacterial cell. This process is essential for ensuring accurate segregation of the low-copy number plasmid and is the best characterised example of DNA partitioning in prokaryotes. In vivo, ParM only forms long filaments when capped at both ends by attachment to a centromere-like region parC, through a small DNA-binding protein ParR. Here, we present biochemical and electron microscopy data leading to a model for the mechanism by which ParR-parC complexes bind and stabilise elongating ParM filaments. We propose that the open ring formed by oligomeric ParR dimers with parC DNA wrapped around acts as a rigid clamp, which holds the end of elongating ParM filaments while allowing entry of new ATP-bound monomers. We propose a processive mechanism by which cycles of ATP hydrolysis in polymerising ParM drives movement of ParR-bound parC DNA. Importantly, our model predicts that each pair of plasmids will be driven apart in the cell by just a single double helical ParM filament. PMID:18650930

  7. Cavity- and waveguide-resonators in electron paramagnetic resonance, nuclear magnetic resonance, and magnetic resonance imaging.

    PubMed

    Webb, Andrew

    2014-11-01

    Cavity resonators are widely used in electron paramagnetic resonance, very high field magnetic resonance microimaging and also in high field human imaging. The basic principles and designs of different forms of cavity resonators including rectangular, cylindrical, re-entrant, cavity magnetrons, toroidal cavities and dielectric resonators are reviewed. Applications in EPR and MRI are summarized, and finally the topic of traveling wave MRI using the magnet bore as a waveguide is discussed. PMID:25456314

  8. Magnetic resonance of slotted circular cylinder resonators

    NASA Astrophysics Data System (ADS)

    Du, Junjie; Liu, Shiyang; Lin, Zhifang; Chui, S. T.

    2008-07-01

    By a rigorous full-wave approach, a systemic study is made on the magnetic resonance of slotted circular cylinder resonators (SCCRs) made of a perfect conductor for the lossless case. This is a two-dimensional analog of the split-ring resonator and may serve as an alternative type of essential constituent of electromagnetic metamaterials. It is found that the resonance frequency can be modulated by changing the geometrical parameters and the dielectrics filling in the cavity and the slot. An approximate empirical expression is presented for magnetic resonance frequency of SCCRs from the viewpoint of an L-C circuit system. Finally, it is demonstrated that the SCCR structure can be miniaturized to less than 1/150 resonant wavelength in size with the dielectrics available currently.

  9. PH motifs in PAR1&2 endow breast cancer growth

    PubMed Central

    Kancharla, A.; Maoz, M.; Jaber, M.; Agranovich, D.; Peretz, T.; Grisaru-Granovsky, S.; Uziely, B.; Bar-Shavit, R.

    2015-01-01

    Although emerging roles of protease-activated receptor1&2 (PAR1&2) in cancer are recognized, their underlying signalling events are poorly understood. Here we show signal-binding motifs in PAR1&2 that are critical for breast cancer growth. This occurs via the association of the pleckstrin homology (PH) domain with Akt/PKB as a key signalling event of PARs. Other PH-domain signal-proteins such as Etk/Bmx and Vav3 also associate with PAR1 and PAR2 through their PH domains. PAR1 and PAR2 bind with priority to Etk/Bmx. A point mutation in PAR2, H349A, but not in R352A, abrogates PH-protein association and is sufficient to markedly reduce PAR2-instigated breast tumour growth in vivo and placental extravillous trophoblast (EVT) invasion in vitro. Similarly, the PAR1 mutant hPar1-7A, which is unable to bind the PH domain, reduces mammary tumours and EVT invasion, endowing these motifs with physiological significance and underscoring the importance of these previously unknown PAR1 and PAR2 PH-domain-binding motifs in both pathological and physiological invasion processes. PMID:26600192

  10. PH motifs in PAR1&2 endow breast cancer growth.

    PubMed

    Kancharla, A; Maoz, M; Jaber, M; Agranovich, D; Peretz, T; Grisaru-Granovsky, S; Uziely, B; Bar-Shavit, R

    2015-01-01

    Although emerging roles of protease-activated receptor1&2 (PAR1&2) in cancer are recognized, their underlying signalling events are poorly understood. Here we show signal-binding motifs in PAR1&2 that are critical for breast cancer growth. This occurs via the association of the pleckstrin homology (PH) domain with Akt/PKB as a key signalling event of PARs. Other PH-domain signal-proteins such as Etk/Bmx and Vav3 also associate with PAR1 and PAR2 through their PH domains. PAR1 and PAR2 bind with priority to Etk/Bmx. A point mutation in PAR2, H349A, but not in R352A, abrogates PH-protein association and is sufficient to markedly reduce PAR2-instigated breast tumour growth in vivo and placental extravillous trophoblast (EVT) invasion in vitro. Similarly, the PAR1 mutant hPar1-7A, which is unable to bind the PH domain, reduces mammary tumours and EVT invasion, endowing these motifs with physiological significance and underscoring the importance of these previously unknown PAR1 and PAR2 PH-domain-binding motifs in both pathological and physiological invasion processes. PMID:26600192

  11. Radiological impact of Par Pond drawdown from liquid effluent pathways

    SciTech Connect

    Carlton, W.H.; Hamby, D.M.

    1991-10-25

    The water level of Par Pond has been lowered over the past several months to reduce the effects in the event of catastrophic dam failure while assessing the condition of the dam and determining if repairs are necessary. In lowering the level of Par Pond, 60 billion liters of water containing low levels of tritium and cesium-137 were discharged to several onsite streams. SRS surface streams flow to the Savannah River. An assessment made to determine the total amount of tritium and Cs-137 discharged and to estimate the consequences to downstream Savannah River users. It is estimated that a total of 160 curies of tritium were displaced from Par Pond to the Savannah River between June 28, 1991 and September 19, 1991. This release could hypothetically result in a maximum individual dose of 3. 2{times}10{sup {minus}4} mrem and a total (80-km and drinking water populations) population dose of 1.4{times}10{sup {minus}2} person-rem. Likewise, a maximum individual dose of 5.0{times}10{sup {minus}2} mrem and a total population dose of 1.7{times}10{sup {minus}1} person- rem are predicted as a result of an estimated 0.21 curies of Cs-137 being discharged from Par Pond to the Savannah River.

  12. Aqueous misdirection following pars plana vitrectomy and silicone oil injection

    PubMed Central

    Ghoraba, Hammouda H; Ghali, Ali Ahmed; Mansour, Hosam Othman

    2015-01-01

    Purpose To report a retrospective series of seven phakic eyes of seven patients suffering from a malignant glaucoma-like syndrome following pars plana vitrectomy and silicone oil (SO) injection. Materials and methods Seven eyes with retinal detachment treated with pars plana vitrectomy with or without scleral buckling with SO tamponade. This was followed by cataract extraction to manage the elevated intraocular pressure (IOP). Results This was a retrospective review of seven cases that received pars plana vitrectomy and SO with or without scleral buckling for different causes of retinal detachment (three were rhegmatogenous and four were tractional). After a period ranging from 1 week to 1 month, they presented with malignant glaucoma-like manifestations; high IOP, shallow axial anterior chamber, and remarkable decrease of visual acuity. Atropine eye drops and anti-glaucoma medical treatment (topical and systemic) had been tried but failed to improve the condition. Dramatic decrease of IOP and deepening of the axial anterior chamber was observed in all cases in the first postoperative day after phacoemulsification and posterior chamber foldable intraocular lens implantation with posterior capsulotomy. Conclusion Aqueous misdirection syndrome may be observed following pars plana vitrectomy and SO tamponade. This must be differentiated from other causes of post vitrectomy glaucoma. Cataract extraction with posterior capsulotomy controls the condition. PMID:26056429

  13. The Pars Triangularis in Dyslexia and ADHD: A Comprehensive Approach

    ERIC Educational Resources Information Center

    Kibby, Michelle Y.; Kroese, Judith M.; Krebbs, Hillery; Hill, Crystal E.; Hynd, George W.

    2009-01-01

    Limited research has been conducted on the structure of the pars triangularis (PT) in dyslexia despite functional neuroimaging research finding it may play a role in phonological processing. Furthermore, research to date has not examined PT size in ADHD even though the right inferior frontal region has been implicated in the disorder. Hence, one…

  14. BOREAS RSS-10 TOMS Circumpolar One-Degree PAR Images

    NASA Technical Reports Server (NTRS)

    Dye, Dennis G.; Holben, Brent; Nickeson, Jaime (Editor); Hall, Forrest G. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Remote Sensing Science (RSS)-10 team investigated the magnitude of daily, seasonal, and yearly variations of Photosynthetically Active Radiation (PAR) from ground and satellite observations. This data set contains satellite estimates of surface-incident PAR (400-700 nm, MJ/sq m) at one-degree spatial resolution. The spatial coverage is circumpolar from latitudes of 41 to 66 degrees north. The temporal coverage is from May through September for years 1979 through 1989. Eleven-year statistics are also provided: (1) mean, (2) standard deviation, and (3) coefficient of variation for 1979-89. The PAR estimates were derived from the global gridded ultraviolet reflectivity data product (average of 360, 380 nm) from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS). Image mask data are provided for identifying the boreal forest zone, and ocean/land and snow/ice-covered areas. The data are available as binary image format data files. The PAR data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  15. Par Pond vegetation status summer 1995 - July survey descriptive summary

    SciTech Connect

    Mackey, H.E. Jr.; Riley, R.S.

    1995-07-01

    A survey of the emergent shoreline aquatic plant, communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet (61 meters) above mean sea level, and continued with this July survey. Aquatic plant communities, similar to the pre-drawdown Par Pond communities, are becoming reestablished. Beds of maidencane (Panicum hemitomon), lotus (Nelumbo lutea), water lily (Nymphaea odorata), and watershield (Brasenia schreberi) are now extensive and well established. In addition, within isolated coves, extensive beds of water lilies and spike-rush (Eleocharis sp.) are common. Cattail occurrence has increased since refill, but large beds common to Par Pond prior to the drawdown have not formed. Invasion of willow (Salix sp.) and red maple (Acer rubrum) occurred along the lake shoreline during drawdown. The red maples along the present shoreline are beginning to show evidence of stress and mortality from flooding over the past four months. Some of the willows appear to be stressed as well. The loblolly pines (Pinus taeda), which were flooded in all but the shallow shoreline areas, are now dead. Future surveys are planned for the growing seasons of 1995, 1996, and 1997, along with the evaluation of satellite data for mapping the areal extent of the macrophyte beds of Par Pond.

  16. Results of peripheral laser photocoagulation in pars planitis.

    PubMed Central

    Pulido, J S; Mieler, W F; Walton, D; Kuhn, E; Postel, E; Hartz, A; Jampol, L M; Weinberg, D V; Logani, S

    1998-01-01

    PURPOSE: To determine the effect of peripheral retinal laser photocoagulation (PLP) on visual acuity, intraocular inflammation, and other ocular findings, including retinal neovascularization in eyes with pars planitis. METHODS: A retrospective chart review of eyes with pars planitis that had undergone PLP. RESULTS: Twenty-two eyes in 17 patients with pars planitis had undergone treatment with PLP at 2 centers. The mean age at the time of treatment was 19.3 years. Following treatment, mean follow-up was 16.3 months (range, 6 to 37 months). Mean visual acuity was 20/60 preoperatively and 20/50 postoperatively. This level of improvement was not statistically significant (P > .10), but there was a statistically significant decrease in the use of corticosteroids between the preoperative examination and the last postoperative examination (86% versus 27%, P < .05). There was also a statistically significant decrease in vitritis at the last follow-up (P = .0008) and a decrease in neovascularization of the vitreous base (P = .03) and in clinically apparent cystoid macular edema (P = .02). Epiretinal membranes were noted in 23% of eyes preoperatively and in 45% of eyes postoperatively. Only one of these epiretinal membranes was considered to be visually significant. One eye developed a tonic dilated pupil, which slowly improved. CONCLUSIONS: Although the long-term natural history of clinical findings in pars planitis is not well documented, PLP appears to decrease the need for corticosteroids while stabilizing visual acuity. It also appears to decrease vitreous inflammation. PLP has few complications and should be considered in patients with pars planitis who are unresponsive or have adverse reactions to corticosteroids. PMID:10360286

  17. The role of pars flaccida in human middle ear sound transmission.

    PubMed

    Aritomo, H; Goode, R L; Gonzalez, J

    1988-04-01

    The role of the pars flaccida in middle ear sound transmission was studied with the use of twelve otoscopically normal, fresh, human temporal bones. Peak-to-peak umbo displacement in response to a constant sound pressure level at the tympanic membrane was measured with a noncontacting video measuring system capable of repeatable measurements down to 0.2 micron. Measurements were made before and after pars flaccida modifications at 18 frequencies between 100 and 4000 Hz. Four pars flaccida modifications were studied: (1) acoustic insulation of the pars flaccida to the ear canal with a silicone rubber baffle, (2) stiffening the pars flaccida with cyanoacrylate cement, (3) decreasing the tension of the pars flaccida with a nonperforating incision, and (4) perforation of the pars flaccida. All of the modifications (except the perforation) had a minimal effect on umbo displacement; this seems to imply that the pars flaccida has a minor acoustic role in human beings. PMID:3132684

  18. Integral resonator gyroscope

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor); Hayworth, Ken J. (Inventor); Wiberg, Dean V. (Inventor); Yee, Karl Y. (Inventor)

    2008-01-01

    The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

  19. The Role of Prostate Apoptosis Response-4 (Par-4) in Mycobacterium tuberculosis Infected Macrophages.

    PubMed

    Han, Ji-Ye; Lim, Yun-Ji; Choi, Ji-Ae; Lee, Jung-Hwan; Jo, Sung-Hee; Oh, Sung-Man; Song, Chang-Hwa

    2016-01-01

    Prostate apoptosis response-4 (Par-4) is a tumor suppressor protein that forms a complex with glucose-regulated protein 78 (GRP78) to induce apoptosis. Previously, we reported that ER stress-induced apoptosis is a critical host defense mechanism against Mycobacterium tuberculosis (Mtb). We sought to understand the role of Par-4 during ER stress-induced apoptosis in response to mycobacterial infection. Par-4 and GRP78 protein levels increased in response Mtb (strain: H37Ra) infection. Furthermore, Par-4 and GRP78 translocate to the surface of Mtb H37Ra-infected macrophages and induce apoptosis via caspase activation. NF-κB activation, Mtb-mediated ER stress, and Par-4 production were significantly diminished in macrophages with inhibited ROS production. To test Par-4 function during mycobacterial infection, we analyzed intracellular survival of Mtb H37Ra in macrophages with Par-4 overexpression or knockdown. Mtb H37Ra growth was significantly reduced in Par-4 overexpressing macrophages and increased in knockdown macrophages. We also observed increased Par-4, GRP78, and caspases activation in Bacillus Calmette-Guérin (BCG)-infected prostate cancer cells. Our data demonstrate that Par-4 is associated with ER stress-induced apoptosis resulting in reduced intracellular survival of mycobacteria. BCG treatment increases Par-4-dependent caspase activation in prostate cancer cells. These results suggest ER stress-induced Par-4 acts as an important defense mechanism against mycobacterial infection and regulates cancer. PMID:27552917

  20. The Role of Prostate Apoptosis Response-4 (Par-4) in Mycobacterium tuberculosis Infected Macrophages

    PubMed Central

    Han, Ji-Ye; Lim, Yun-Ji; Choi, Ji-Ae; Lee, Jung-hwan; Jo, Sung-Hee; Oh, Sung-Man; Song, Chang-Hwa

    2016-01-01

    Prostate apoptosis response-4 (Par-4) is a tumor suppressor protein that forms a complex with glucose-regulated protein 78 (GRP78) to induce apoptosis. Previously, we reported that ER stress-induced apoptosis is a critical host defense mechanism against Mycobacterium tuberculosis (Mtb). We sought to understand the role of Par-4 during ER stress-induced apoptosis in response to mycobacterial infection. Par-4 and GRP78 protein levels increased in response Mtb (strain: H37Ra) infection. Furthermore, Par-4 and GRP78 translocate to the surface of Mtb H37Ra-infected macrophages and induce apoptosis via caspase activation. NF-κB activation, Mtb-mediated ER stress, and Par-4 production were significantly diminished in macrophages with inhibited ROS production. To test Par-4 function during mycobacterial infection, we analyzed intracellular survival of Mtb H37Ra in macrophages with Par-4 overexpression or knockdown. Mtb H37Ra growth was significantly reduced in Par-4 overexpressing macrophages and increased in knockdown macrophages. We also observed increased Par-4, GRP78, and caspases activation in Bacillus Calmette-Guérin (BCG)-infected prostate cancer cells. Our data demonstrate that Par-4 is associated with ER stress-induced apoptosis resulting in reduced intracellular survival of mycobacteria. BCG treatment increases Par-4-dependent caspase activation in prostate cancer cells. These results suggest ER stress-induced Par-4 acts as an important defense mechanism against mycobacterial infection and regulates cancer. PMID:27552917

  1. Is There an "F" in Your PAR? Understanding, Teaching and Doing Action Research

    ERIC Educational Resources Information Center

    Lorenzetti, Liza; Walsh, Christine Ann

    2014-01-01

    Participatory Action Research (PAR) is increasingly recognized within academic research and pedagogy. What are the benefits of including feminism within participatory action research and teaching? In responding to this question, we discuss the similarities and salient differences between PAR and feminist informed PAR (FPAR). There are eight themes…

  2. ParA resolvase catalyzes site-specific excision of DNA from the Arabidopsis genome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The small serine resolvase ParA from bacterial plasmids RK2 and RP4 catalyzes the recombination of two identical 133 bp recombination sites known as MRS. Previously, we reported that ParA is active in the fission yeast Schizosaccharomyces pombe. In this work, the parA recombinase gene was placed un...

  3. Detection of suPAR in the Saliva of Healthy Young Adults: Comparison with Plasma Levels

    PubMed Central

    Gustafsson, Anna; Ajeti, Vjosa; Ljunggren, Lennart

    2011-01-01

    The soluble urokinase plasminogen activator receptor (suPAR) has been detected in blood, plasma, serum, urine, ovarian cystic fluid, and cerebrospinal fluid. Elevated suPAR levels in plasma have been associated with negative outcomes in various diseases, such as bacteremia, sepsis, SIRS, cardiovascular disease, cancer, and tuberculosis. The primary aim of this study was to investigate whether suPAR can be detected in saliva from healthy individuals and thus, if saliva suPAR can be related to plasma suPAR, CRP, BMI, or gender. Blood and unstimulated whole saliva was collected from 20 healthy individuals (10 female and 10 male, median age of 28 years; range 21–41). CRP and suPAR were measured with ELISA in saliva and serum/plasma. suPAR was detected in all saliva samples in the 5.2–28.1 ng/mL range, with a median value of 17.1 ng/mL. Saliva suPAR was significantly higher (P < 0.001) but not correlated to plasma suPAR in healthy young adults with normal plasma suPAR levels. suPAR and CRP levels were correlated in blood but not in saliva. No correlation was found between BMI, age, or gender and suPAR in saliva. PMID:22084570

  4. Nanomechanical resonance detector

    DOEpatents

    Grossman, Jeffrey C; Zettl, Alexander K

    2013-10-29

    An embodiment of a nanomechanical frequency detector includes a support structure and a plurality of elongated nanostructures coupled to the support structure. Each of the elongated nanostructures has a particular resonant frequency. The plurality of elongated nanostructures has a range of resonant frequencies. An embodiment of a method of identifying an object includes introducing the object to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the object. An embodiment of a method of identifying a molecular species of the present invention includes introducing the molecular species to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the molecular species.

  5. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  6. ParCAT: A Parallel Climate Analysis Toolkit

    NASA Astrophysics Data System (ADS)

    Haugen, B.; Smith, B.; Steed, C.; Ricciuto, D. M.; Thornton, P. E.; Shipman, G.

    2012-12-01

    Climate science has employed increasingly complex models and simulations to analyze the past and predict the future of our climate. The size and dimensionality of climate simulation data has been growing with the complexity of the models. This growth in data is creating a widening gap between the data being produced and the tools necessary to analyze large, high dimensional data sets. With single run data sets increasing into 10's, 100's and even 1000's of gigabytes, parallel computing tools are becoming a necessity in order to analyze and compare climate simulation data. The Parallel Climate Analysis Toolkit (ParCAT) provides basic tools that efficiently use parallel computing techniques to narrow the gap between data set size and analysis tools. ParCAT was created as a collaborative effort between climate scientists and computer scientists in order to provide efficient parallel implementations of the computing tools that are of use to climate scientists. Some of the basic functionalities included in the toolkit are the ability to compute spatio-temporal means and variances, differences between two runs and histograms of the values in a data set. ParCAT is designed to facilitate the "heavy lifting" that is required for large, multidimensional data sets. The toolkit does not focus on performing the final visualizations and presentation of results but rather, reducing large data sets to smaller, more manageable summaries. The output from ParCAT is provided in commonly used file formats (NetCDF, CSV, ASCII) to allow for simple integration with other tools. The toolkit is currently implemented as a command line utility, but will likely also provide a C library for developers interested in tighter software integration. Elements of the toolkit are already being incorporated into projects such as UV-CDAT and CMDX. There is also an effort underway to implement portions of the CCSM Land Model Diagnostics package using ParCAT in conjunction with Python and gnuplot. Par

  7. An Inexpensive Resonance Demonstration

    ERIC Educational Resources Information Center

    Dukes, Phillip

    2005-01-01

    The phenomenon of resonance is applicable to almost every branch of physics. Without resonance, there wouldn't be televisions or stereos, or even swings on the playground. However, resonance also has undesirable side effects such as irritating noises in the car and the catastrophic events such as helicopters flying apart. In this article, the…

  8. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Andrew, E. R.

    2009-06-01

    Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

  9. Magnetic Resonance Imaging (MRI)

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Magnetic Resonance Imaging (MRI) KidsHealth > For Teens > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's ... Exam Safety Getting Your Results What Is MRI? Magnetic resonance imaging (MRI) is a type of safe, painless testing ...

  10. Mesure du coewicient d'absorption optique dans le silicium multicristallin de type P pour photopiles solaires

    NASA Astrophysics Data System (ADS)

    Gervais, J.

    1993-07-01

    The minority carrier diffusion length L characterizes the electrical quality of multicrystalline silicon wafers used for photovoltaics. Its determination before and after different treatments (impurity diffusion, passivation, metallisation) is needfull and requires the accurate knowledge of the optical absorption coefficient α in the near infrared. We have determinated the spectral variation of α in the range between 0.86 and 1.06 μm and we propose an analytic expression which is very close to those proposed for solar grade single crystals. In addition we have verified that the values of α are not affected by long phosphorus diffusion needed to getter metallic impurities. La longueur de diffusion des porteurs minoritaires L caractérise la qualité du silicium multicristallin utilisé pour la conversion photovoltaïque. Sa détermination avant et après les divers traitements (diffusion d'impuretés, passivation des défauts, métallisation) est indispensable et nécessite la connaissance précise du coefficient d'absorption optique α dans le proche infrarouge. Nous avons déterminé expérimentalement la variation spectrale de α entre 0,86 et 1,06 μm et nous proposons un développement qui est très proche de ceux trouvés dans des monocristaux de silicium de qualité solaire. La variation de α n'est pas influencée par des diffusions de phosphore prolongées nécessaires à l'extraction et au piégeage d'impuretés métalliques.

  11. Minimally invasive pars approach for foraminal disc herniation.

    PubMed

    Hitchon, Patrick W; Awe, Olatilewa O; Close, Liesl; Sukkarieh, Hamdi G

    2015-07-01

    We present a retrospective cohort study on the outcome of patients with foraminal disc herniations (FDH) treated with partial pars resections using minimally invasive surgery (MIS) through a tube. FDH present a challenge due to the more lateral trajectory needed for their excision and thereby more muscle dissection and possibly facet resection. Forty patients, 19 women and 21 men with a mean age ± standard deviation of 58 ± 12 years, underwent MIS for FDH. Data on length of hospital stay, body mass index and outcomes were collected prospectively and reviewed retrospectively. Average length of stay following surgery was 1 ± 1 days. There was one wound infection and four unsatisfactory results. Using the Macnab score, good to excellent results were achieved in 89% of the patients. Based on these results, MIS surgery with partial pars resection is an attractive option in the treatment of FDH with low morbidity and short hospital stays. PMID:25882259

  12. Ovenized microelectromechanical system (MEMS) resonator

    SciTech Connect

    Olsson, Roy H; Wojciechowski, Kenneth; Kim, Bongsang

    2014-03-11

    An ovenized micro-electro-mechanical system (MEMS) resonator including: a substantially thermally isolated mechanical resonator cavity; a mechanical oscillator coupled to the mechanical resonator cavity; and a heating element formed on the mechanical resonator cavity.

  13. The Pars Interarticularis Stress Reaction, Spondylolysis, and Spondylolisthesis Progression

    PubMed Central

    Motley, Gina; Nyland, John; Jacobs, Jake; Caborn, David N. M.

    1998-01-01

    Objective: To review the classification, etiology, clinical and radiologic evaluation, and management of the pars interarticularis stress reaction, spondylolysis, and spondylolisthesis progression. Data Sources: Grateful Med was searched from 1980 to 1998 using the terms “spondylolysis,” “spondylolisthesis,” “female athlete” “spondylogenic,” and “pars interarticularis.” Data Synthesis: The progression from pars interarticularis stress reaction through spondylolysis to spondylolisthesis is common in adolescent athletes, and, because of hormonal influences and cheerleading and gymnastic maneuvers, females are particularly at risk. Proper diagnosis and management include a thorough evaluation, radiographs (possibly with technetium bone scan or single-photon emission computed tomography), activity modification, dietary counseling, a therapeutic exercise program focusing on proper trunk and hip muscle strength and extensibility balances, and education regarding proper back postures, positioning, lifting mechanics, and jump landings. Conclusions/Recommendations: The athletic trainer plays an integral part in managing this injury progression, particularly with identifying at-risk individuals and intervening appropriately. ImagesFigure 4. PMID:16558534

  14. ParB Partition Proteins: Complex Formation and Spreading at Bacterial and Plasmid Centromeres

    PubMed Central

    Funnell, Barbara E.

    2016-01-01

    In bacteria, active partition systems contribute to the faithful segregation of both chromosomes and low-copy-number plasmids. Each system depends on a site-specific DNA binding protein to recognize and assemble a partition complex at a centromere-like site, commonly called parS. Many plasmid, and all chromosomal centromere-binding proteins are dimeric helix-turn-helix DNA binding proteins, which are commonly named ParB. Although the overall sequence conservation among ParBs is not high, the proteins share similar domain and functional organization, and they assemble into similar higher-order complexes. In vivo, ParBs “spread,” that is, DNA binding extends away from the parS site into the surrounding non-specific DNA, a feature that reflects higher-order complex assembly. ParBs bridge and pair DNA at parS and non-specific DNA sites. ParB dimers interact with each other via flexible conformations of an N-terminal region. This review will focus on the properties of the HTH centromere-binding protein, in light of recent experimental evidence and models that are adding to our understanding of how these proteins assemble into large and dynamic partition complexes at and around their specific DNA sites. PMID:27622187

  15. Dynamic Filament Formation by a Divergent Bacterial Actin-Like ParM Protein

    PubMed Central

    Brzoska, Anthony J.; Jensen, Slade O.; Barton, Deborah A.; Davies, Danielle S.; Overall, Robyn L.; Skurray, Ronald A.; Firth, Neville

    2016-01-01

    Actin-like proteins (Alps) are a diverse family of proteins whose genes are abundant in the chromosomes and mobile genetic elements of many bacteria. The low-copy-number staphylococcal multiresistance plasmid pSK41 encodes ParM, an Alp involved in efficient plasmid partitioning. pSK41 ParM has previously been shown to form filaments in vitro that are structurally dissimilar to those formed by other bacterial Alps. The mechanistic implications of these differences are not known. In order to gain insights into the properties and behavior of the pSK41 ParM Alp in vivo, we reconstituted the parMRC system in the ectopic rod-shaped host, E. coli, which is larger and more genetically amenable than the native host, Staphylococcus aureus. Fluorescence microscopy showed a functional fusion protein, ParM-YFP, formed straight filaments in vivo when expressed in isolation. Strikingly, however, in the presence of ParR and parC, ParM-YFP adopted a dramatically different structure, instead forming axial curved filaments. Time-lapse imaging and selective photobleaching experiments revealed that, in the presence of all components of the parMRC system, ParM-YFP filaments were dynamic in nature. Finally, molecular dissection of the parMRC operon revealed that all components of the system are essential for the generation of dynamic filaments. PMID:27310470

  16. ParB Partition Proteins: Complex Formation and Spreading at Bacterial and Plasmid Centromeres.

    PubMed

    Funnell, Barbara E

    2016-01-01

    In bacteria, active partition systems contribute to the faithful segregation of both chromosomes and low-copy-number plasmids. Each system depends on a site-specific DNA binding protein to recognize and assemble a partition complex at a centromere-like site, commonly called parS. Many plasmid, and all chromosomal centromere-binding proteins are dimeric helix-turn-helix DNA binding proteins, which are commonly named ParB. Although the overall sequence conservation among ParBs is not high, the proteins share similar domain and functional organization, and they assemble into similar higher-order complexes. In vivo, ParBs "spread," that is, DNA binding extends away from the parS site into the surrounding non-specific DNA, a feature that reflects higher-order complex assembly. ParBs bridge and pair DNA at parS and non-specific DNA sites. ParB dimers interact with each other via flexible conformations of an N-terminal region. This review will focus on the properties of the HTH centromere-binding protein, in light of recent experimental evidence and models that are adding to our understanding of how these proteins assemble into large and dynamic partition complexes at and around their specific DNA sites. PMID:27622187

  17. Optical Helmholtz resonators

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Haïdar, Riad; Pardo, Fabrice

    2014-08-01

    Helmholtz resonators are widely used acoustic components able to select a single frequency. Here, based on an analogy between acoustics and electromagnetism wave equations, we present an electromagnetic 2D Helmholtz resonator made of a metallic slit-box structure. At the resonance, the light is funneled in the λ/800 apertures, and is subsequently absorbed in the cavity. As in acoustics, there is no higher order of resonance, which is an appealing feature for applications such as photodetection or thermal emission. Eventually, we demonstrate that the slit is of capacitive nature while the box behaves inductively. We derive an analytical formula for the resonance wavelength, which does not rely on wave propagation and therefore does not depend on the permittivity of the material filling the box. Besides, in contrast with half-wavelength resonators, the resonance wavelength can be engineered by both the slit aspect ratio and the box area.

  18. Structure of the ParM filament at 8.5 Å resolution

    PubMed Central

    Gayathri, Pananghat; Fujii, Takashi; Namba, Keiichi; Löwe, Jan

    2013-01-01

    The actin-like protein ParM forms the cytomotive filament of the ParMRC system, a type II plasmid segregation system encoded by Escherichia coli R1 plasmid. We report an 8.5 Å resolution reconstruction of the ParM filament, obtained using cryo-electron microscopy. Fitting of the 3D density reconstruction with monomeric crystal structures of ParM provides insights into dynamic instability of ParM filaments. The structural analysis suggests that a ParM conformation, corresponding to a metastable state, is held within the filament by intrafilament contacts. This filament conformation of ParM can be attained only from the ATP-bound state, and induces a change in conformation of the bound nucleotide. The structural analysis also provides a rationale for the observed stimulation of hydrolysis upon polymerisation into the filament. PMID:23462100

  19. ParA resolvase catalyzes site-specific excision of DNA from the Arabidopsis genome.

    PubMed

    Thomson, James G; Yau, Yuan-Yeu; Blanvillain, Robert; Nunes, Wylla M; Chiniquy, Dawn; Thilmony, Roger; Ow, David W

    2009-04-01

    The small serine resolvase ParA from bacterial plasmids RK2 and RP4 catalyzes the recombination of two identical 133 bp recombination sites known as MRS. Previously, we reported that ParA is active in the fission yeast Schizosaccharomyces pombe. In this work, the parA recombinase gene was placed under the control of the Arabidopsis OXS3 promoter and introduced into Arabidopsis lines harboring a chromosomally integrated MRS-flanked target. The ParA recombinase excised the MRS-flanked DNA and the excision event was detected in subsequent generations in the absence of ParA, indicating germinal transmission of the excision event. The precise site-specific deletion by the ParA recombination system in planta demonstrates that the ParA recombinase can be used to remove transgenic DNA, such as selectable markers or other introduced transgenes that are no longer desired in the final product. PMID:18704739

  20. Magnetic resonance energy and topological resonance energy.

    PubMed

    Aihara, Jun-Ichi

    2016-04-28

    Ring-current diamagnetism of a polycyclic π-system is closely associated with thermodynamic stability due to the individual circuits. Magnetic resonance energy (MRE), derived from the ring-current diamagnetic susceptibility, was explored in conjunction with graph-theoretically defined topological resonance energy (TRE). For many aromatic molecules, MRE is highly correlative with TRE with a correlation coefficient of 0.996. For all π-systems studied, MRE has the same sign as TRE. The only trouble with MRE may be that some antiaromatic and non-alternant species exhibit unusually large MRE-to-TRE ratios. This kind of difficulty can in principle be overcome by prior geometry-optimisation or by changing spin multiplicity. Apart from the semi-empirical resonance-theory resonance energy, MRE is considered as the first aromatic stabilisation energy (ASE) defined without referring to any hypothetical polyene reference. PMID:26878709

  1. Resonance splitting in gyrotropic ring resonators.

    PubMed

    Jalas, Dirk; Petrov, Alexander; Krause, Michael; Hampe, Jan; Eich, Manfred

    2010-10-15

    We present the theoretical concept of an optical isolator based on resonance splitting in a silicon ring resonator covered with a magneto-optical polymer cladding. For this task, a perturbation method is derived for the modes in the cylindrical coordinate system. A polymer magneto-optical cladding causing a 0.01 amplitude of the off-diagonal element of the dielectric tensor is assumed. It is shown that the derived resonance splitting of the clockwise and counterclockwise modes increases for smaller ring radii. For the ring with a radius of approximately 1.5μm, a 29GHz splitting is demonstrated. An integrated optical isolator with a 10μm geometrical footprint is proposed based on a critically coupled ring resonator. PMID:20967092

  2. Contribution à la modélisation du soudage TIG des tôles minces d'acier austénitique 304L par un modèle source bi-elliptique, avec confrontation expérimentale

    NASA Astrophysics Data System (ADS)

    Aissani, M.; Maza, H.; Belkessa, B.; Maamache, B.

    2005-05-01

    Ce travail contribue dans la modélisation du phénomène du soudage de l'acier inoxydable Austénitique 304L, afin d'étudier le comportement thermique d'un joint de soudure, obtenu par le procédé de soudage à l'arc électrique TIG (Tungsten-Inert-Gas). Le modèle simulant la source d'énergie de soudage, utilise une distribution surfacique Gaussienne du flux de chaleur provenant de l'arc électrique. La forme de cette source est supposée circulaire pour un premier cas et de forme bi-elliptique pour un second cas, tout en procédant à l'évaluation des champs et cycles thermiques à chaque instant, pour déterminer l'étendu des zones à risque, et l'effet de la vitesse de soudage sur ces dernières. Permettant ainsi de remonter par la suite, aux problèmes de contraintes résiduelles et déformations générées dans l'assemblage soudé. L'équation de chaleur régissant le problème est discrétisée par la méthode des volumes finis. Les calculs sont effectués en considérant que les propriétés physiques et thermiques ainsi que les conditions aux limites de convection et rayonnement, sont dépendante de la température. Pour évaluer la précision du modèle, une comparaison avec des mesures expérimentales de température d'un essai de soudage a été effectuée, les résultats indiquent un bon accord.

  3. Is PAR a Good Investment? Understanding the Costs and Benefits of Teacher Peer Assistance and Review Programs

    ERIC Educational Resources Information Center

    Papay, John P.; Johnson, Susan Moore

    2012-01-01

    Peer Assistance and Review (PAR) is a local labor-management initiative designed to improve teacher quality. In PAR, expert "consulting teachers" mentor, support, and evaluate novice and underperforming veteran teachers. Evaluations under PAR can lead to dismissals. The authors examine the costs and benefits of PAR, both financial and…

  4. Excitonic surface lattice resonances

    NASA Astrophysics Data System (ADS)

    Humphrey, A. D.; Gentile, M. J.; Barnes, W. L.

    2016-08-01

    Electromagnetic resonances are important in controlling light at the nanoscale. The most studied such resonance is the surface plasmon resonance that is associated with metallic nanostructures. Here we explore an alternative resonance, the surface exciton-polariton resonance, one based on excitonic molecular materials. Our study is based on analytical and numerical modelling. We show that periodic arrays of suitable molecular nanoparticles may support surface lattice resonances that arise as a result of coherent interactions between the particles. Our results demonstrate that excitonic molecular materials are an interesting alternative to metals for nanophotonics; they offer the prospect of both fabrication based on supramolecular chemistry and optical functionality arising from the way the properties of such materials may be controlled with light.

  5. An ELISA method detecting the active form of suPAR.

    PubMed

    Zhou, Xiaolei; Xu, Mingming; Huang, Hailong; Mazar, Andrew; Iqbal, Zafar; Yuan, Cai; Huang, Mingdong

    2016-11-01

    Urokinase plasminogen activator receptor (uPAR) exists in a number of formats in human plasma, including soluble uPAR (suPAR) and uPAR fragments. We developed an ELISA method to detect specifically the active form suPAR, which binds to its natural ligand uPA. The intra CV and inter CV of this ELISA assay is 8.5% and 9.6% respectively, and the assay can recover 99.74% of added recombinant suPAR from 10% plasma. This assay is quite sensitive, capable of detecting down to 15pg/ml of suPAR, and can measure suPAR concentrations in the range of 0.031-8ng/ml with high linear relationship. Plasma samples from pregnant women were also measured for the active form of suPAR with this assay, giving an averaged level of 1.39ng/ml, slightly higher than the level of pooled plasma from healthy donors (0.96ng/ml). This study demonstrates the feasibility to measure the active form of suPAR, which will likely have value in clinical applications. PMID:27591605

  6. Par3 regulates invasion of pancreatic cancer cells via interaction with Tiam1.

    PubMed

    Guo, Xingjun; Wang, Min; Zhao, Yan; Wang, Xin; Shen, Ming; Zhu, Feng; Shi, Chengjian; Xu, Meng; Li, Xu; Peng, Feng; Zhang, Hang; Feng, Yechen; Xie, Yu; Xu, Xiaodong; Jia, Wei; He, Ruizhi; Jiang, Jianxin; Hu, Jun; Tian, Rui; Qin, Renyi

    2016-08-01

    The conserved polarity complex, which comprises partitioning-defective proteins Par3, Par6, and the atypical protein kinase C, affects various cell-polarization events, including assembly of tight junctions. Control of tight junction assembly is closely related to invasion and migration potential. However, as the importance of conserved polarity complexes in regulating pancreatic cancer invasion and metastasis is unclear, we investigated their role and mechanism in pancreatic cancers. We first detect that the key protein of the conserved polarity complex finds that only Par3 is down-regulated in pancreatic cancer tissues while Par6 and aPKC show no difference. What is more, Par3 tissues level was significantly and positively associated with patient overall survival. Knocking-down Par3 promotes pancreatic cancer cells invasion and migration. And Par3 requires interaction with Tiam1 to affect tight junction assembly, and then affect invasion and migration of pancreatic cancer cells. Then, we find that tight junction marker protein ZO-1 and claudin-1 are down-regulated in pancreatic cancer tissues. And the relationship of the expression of Par3 and ZO-1 in pancreatic cancer tissue is linear correlation. We establish liver metastasis model of human pancreatic cancer cells in Balb/c nude mice and find that knocking down Par3 promotes invasion and metastasis and disturbs tight junction assembly in vivo. Taken together, these results suggest that the Par3 regulates invasion and metastasis in pancreatic cancers by controlling tight junction assembly. PMID:26084985

  7. PAR1 is selectively over expressed in high grade breast cancer patients: a cohort study

    PubMed Central

    Hernández, Norma A; Correa, Elma; Avila, Esther P; Vela, Teresa A; Pérez, Víctor M

    2009-01-01

    Background The protease-activated receptor (PAR1) expression is correlated with the degree of invasiveness in cell lines. Nevertheless it has never been directed involved in breast cancer patients progression. The aim of this study was to determine whether PAR1 expression could be used as predictor of metastases and mortality. Methods In a cohort of patients with infiltrating ductal carcinoma studied longitudinally since 1996 and until 2007, PAR1 over-expression was assessed by immunoblotting, immunohistochemistry, and flow citometry. Chi-square and log rank tests were used to determine whether there was a statistical association between PAR1 overexpression and metastases, mortality, and survival. Multivariate analysis was performed including HER1, stage, ER and nodes status to evaluate PAR1 as an independent prognostic factor. Results Follow up was 95 months (range: 2–130 months). We assayed PAR1 in a cohort of patients composed of 136 patients; we found PAR1 expression assayed by immunoblotting was selectively associated with high grade patients (50 cases of the study cohort; P = 0.001). Twenty-nine of 50 (58%) patients overexpressed PAR1, and 23 of these (46%) developed metastases. HER1, stage, ER and PAR1 overexpression were robustly correlated (Cox regression, P = 0.002, P = 0.024 and P = 0.002 respectively). Twenty-one of the 50 patients (42%) expressed both receptors (PAR1 and HER1 P = 0.0004). We also found a statistically significant correlation between PAR1 overexpression and increased mortality (P = 0.0001) and development of metastases (P = 0.0009). Conclusion Our data suggest PAR1 overexpression may be involved in the development of metastases in breast cancer patient and is associated with undifferentiated cellular progression of the tumor. Further studies are needed to understand PAR1 mechanism of action and in a near future assay its potential use as risk factor for metastasis development in high grade breast cancer patients. PMID:19538737

  8. Large mode radius resonators

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.

    1987-01-01

    Resonator configurations permitting operation with large mode radius while maintaining good transverse mode discrimination are considered. Stable resonators incorporating an intracavity telescope and unstable resonator geometries utilizing an output coupler with a Gaussian reflectivity profile are shown to enable large radius single mode laser operation. Results of heterodyne studies of pulsed CO2 lasers with large (11mm e sup-2 radius) fundamental mode sizes are presented demonstrating minimal frequency sweeping in accordance with the theory of laser-induced medium perturbations.

  9. Emerging Roles of PAR-1 and PAFR in Melanoma Metastasis

    PubMed Central

    Melnikova, Vladislava O.; Villares, Gabriel J.

    2008-01-01

    Melanoma growth, angiogenesis and metastatic progression are strongly promoted by the inflammatory tumor microenvironment due to high levels of cytokine and chemokine secretion by the recruited inflammatory and stromal cells. In addition, platelets and molecular components of procoagulant pathways have been recently emerging as critical players of tumor growth and metastasis. In particular, thrombin, through the activity of its receptor protease-activated receptor-1 (PAR-1), regulates tumor cell adhesion to platelets and endothelial cells, stimulates tumor angiogenesis, and promotes tumor growth and metastasis. Notably, in many tumor types including melanoma, PAR-1 expression directly correlates with their metastatic phenotype and is directly responsible for the expression of interleukin-8, matrix metalloproteinase-2 (MMP-2), vascular endothelial growth factor, platelet-derived growth factor, and integrins. Another proinflammatory receptor–ligand pair, platelet-activating factor (PAF) and its receptor (PAFR), have been shown to act as important modulators of tumor cell adhesion to endothelial cells, angiogenesis, tumor growth and metastasis. PAF is a bioactive lipid produced by a variety of cells from membrane glycerophospholipids in the same reaction that releases arachidonic acid, and can be secreted by platelets, inflammatory cells, keratinocytes and endothelial cells. We have demonstrated that in metastatic melanoma cells, PAF stimulates the phosphorylation of cyclic adenosine monophosphate response element-binding protein (CREB) and activating transcription factor 1 (ATF-1), which results in overexpression of MMP-2 and membrane type 1-MMP (membrane type 1-MMP). Since only metastatic melanoma cells overexpress CREB/ATF-1, we propose that metastatic melanoma cells are better equipped than their non-metastatic counterparts to respond to PAF within the tumor microenvironment. The evidence supporting the hypothesis that the two G-protein coupled receptors, PAR-1

  10. Emerging roles of PAR-1 and PAFR in melanoma metastasis.

    PubMed

    Melnikova, Vladislava O; Villares, Gabriel J; Bar-Eli, Menashe

    2008-12-01

    Melanoma growth, angiogenesis and metastatic progression are strongly promoted by the inflammatory tumor microenvironment due to high levels of cytokine and chemokine secretion by the recruited inflammatory and stromal cells. In addition, platelets and molecular components of procoagulant pathways have been recently emerging as critical players of tumor growth and metastasis. In particular, thrombin, through the activity of its receptor protease-activated receptor-1 (PAR-1), regulates tumor cell adhesion to platelets and endothelial cells, stimulates tumor angiogenesis, and promotes tumor growth and metastasis. Notably, in many tumor types including melanoma, PAR-1 expression directly correlates with their metastatic phenotype and is directly responsible for the expression of interleukin-8, matrix metalloproteinase-2 (MMP-2), vascular endothelial growth factor, platelet-derived growth factor, and integrins. Another proinflammatory receptor-ligand pair, platelet-activating factor (PAF) and its receptor (PAFR), have been shown to act as important modulators of tumor cell adhesion to endothelial cells, angiogenesis, tumor growth and metastasis. PAF is a bioactive lipid produced by a variety of cells from membrane glycerophospholipids in the same reaction that releases arachidonic acid, and can be secreted by platelets, inflammatory cells, keratinocytes and endothelial cells. We have demonstrated that in metastatic melanoma cells, PAF stimulates the phosphorylation of cyclic adenosine monophosphate response element-binding protein (CREB) and activating transcription factor 1 (ATF-1), which results in overexpression of MMP-2 and membrane type 1-MMP (membrane type 1-MMP). Since only metastatic melanoma cells overexpress CREB/ATF-1, we propose that metastatic melanoma cells are better equipped than their non-metastatic counterparts to respond to PAF within the tumor microenvironment. The evidence supporting the hypothesis that the two G-protein coupled receptors, PAR-1

  11. A systematic computation scheme of PAR-WIG cruising performance

    NASA Astrophysics Data System (ADS)

    Ando, Shigenori

    1993-08-01

    A systematic computation scheme is presented for PAR-WIG cruising performance, on a FORTRAN program. It is suitable for implementation on PCs. Effects of many parameters on the transportation efficiency are explored. Two concepts are presented in three views and artist impressions. One is a smallest single-crewman vehicle for experiment, sports, or pleasure. The other is a large vehicle for civil transportation. Both have twin hulls, which are quite suitable for installing a 'SMALL-TAIL-WIG' or 'WIG-let' to establish longitudinal attitude stability.

  12. BOREAS TE-12 Incoming PAR Through the Forest Canopy Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Walter-Shea, Elizabeth A.; Mesarch, Mark A.

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-12 (Terrestrial Ecology) team collected photosynthetically active radiation (PAR) data sets in support of its efforts to characterize and interpret information on shoot geometry, leaf optical properties, leaf water potential, and leaf gas exchange. The data were collected at the Southern Study Area-Old Black Spruce (SSA-OBS) site from 04-Jul-1996 to 25-Jul-1996. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  13. Estimating Photosynthetically Available Radiation (PAR) at the Earth's surface from satellite observations

    NASA Technical Reports Server (NTRS)

    Frouin, Robert

    1993-01-01

    Current satellite algorithms to estimate photosynthetically available radiation (PAR) at the earth' s surface are reviewed. PAR is deduced either from an insolation estimate or obtained directly from top-of-atmosphere solar radiances. The characteristics of both approaches are contrasted and typical results are presented. The inaccuracies reported, about 10 percent and 6 percent on daily and monthly time scales, respectively, are useful to model oceanic and terrestrial primary productivity. At those time scales variability due to clouds in the ratio of PAR and insolation is reduced, making it possible to deduce PAR directly from insolation climatologies (satellite or other) that are currently available or being produced. Improvements, however, are needed in conditions of broken cloudiness and over ice/snow. If not addressed properly, calibration/validation issues may prevent quantitative use of the PAR estimates in studies of climatic change. The prospects are good for an accurate, long-term climatology of PAR over the globe.

  14. Fluoroquinolone Resistance Mutations in the parC, parE, and gyrA Genes of Clinical Isolates of Viridans Group Streptococci

    PubMed Central

    González, Irene; Georgiou, Marios; Alcaide, Fernando; Balas, Delia; Liñares, Josefina; de la Campa, Adela G.

    1998-01-01

    The nucleotide sequences of the quinolone resistance-determining regions (QRDRs) of the parC and gyrA genes from seven ciprofloxacin-resistant (Cpr) isolates of viridans group streptococci (two high-level Cpr Streptococcus oralis and five low-level Cpr Streptococcus mitis isolates) were determined and compared with those obtained from susceptible isolates. The nucleotide sequences of the QRDRs of the parE and gyrB genes from the five low-level Cpr S. mitis isolates and from the NCTC 12261 type strain were also analyzed. Four of these low-level Cpr isolates had changes affecting the subunits of DNA topoisomerase IV: three in Ser-79 (to Phe or Ile) of ParC and one in ParE at a position not previously described to be involved in quinolone resistance (Pro-424). One isolate did not show any mutation. The two high-level Cpr S. oralis isolates showed mutations affecting equivalent residue positions of ParC and GyrA, namely, Ser-79 to Phe and Ser-81 to Phe or Tyr, respectively. The parC mutations were able to transform Streptococcus pneumoniae to ciprofloxacin resistance, while the gyrA mutations transformed S. pneumoniae only when mutations in parC were present. These results suggest that DNA topoisomerase IV is a primary target of ciprofloxacin in viridans group streptococci, DNA gyrase being a secondary target. PMID:9797205

  15. Modelisation numerique et validation experimentale d'un systeme de protection contre le givre par elements piezoelectriques

    NASA Astrophysics Data System (ADS)

    Harvey, Derek

    Le degivrage au moyen d'actuateurs piezoelectriques est considere comme une avenue prometteuse pour le developpement de systemes a faible consommation d'energie applicables aux helicopteres legers. Ce type de systeme excite des frequences de resonances d'une structure pour produire des deformations suffisantes pour rompre l'adherence de la glace. Par contre, la conception de tel systeme demeure generalement mal comprise. Ce projet de maitrise etudie l'utilisation de methodes numeriques pour assister la conception des systemes de protection contre le givre a base d'elements piezoelectriques. La methodologie retenue pour ce projet a ete de modeliser differentes structures simples et de simuler l'excitation harmonique des frequences de resonance au moyen d'actuateurs piezoelectriques. Le calcul des frequences de resonances ainsi que la simulation de leur excitation a ensuite ete validee a l'aide de montages experimentaux. La procedure a ete realisee pour une poutre en porte-a-faux et pour une plaque plane a l'aide du logiciel de calcul par elements finis, Abaqus. De plus, le modele de la plaque plane a ete utilise afin de realiser une etude parametrique portant sur le positionnement des actuateurs, l'effet de la rigidite ainsi que de l'epaisseur de la plaque. Finalement, la plaque plane a ete degivree en chambre climatique. Des cas de degivrage ont ete simules numeriquement afin d'etudier la possibilite d'utiliser un critere base sur la deformation pour predire le succes du systeme. La validation experimentale a confirme la capacite du logiciel a calculer precisement a la fois les frequences et les modes de resonance d'une structure et a simuler leur excitation par des actuateurs piezoelectriques. L'etude revele que la definition de l'amortissement dans le modele numerique est essentiel pour l'obtention de resultats precis. Les resultats de l'etude parametrique ont demontre l'importance de minimiser l'epaisseur et la rigidite afin de reduire la valeur des frequences

  16. Resonances in heavy systems

    SciTech Connect

    Betts, R.R.

    1983-01-01

    The experimental situation for the study of resonances in heavy-ion collisions is reviewed, with emphasis on the heaviest systems. New data are presented which show some of the systematics of this phenomenon. The narrow resonance structures are established as a feature of the nuclear structure of the composite system rather than a purely entrance channel effect.

  17. Unstable optical resonators.

    PubMed

    Kahn, W K

    1966-03-01

    A technique, firmly based on a development from ray optics, is presented for calculating the loss due to the finite sizes of curved mirrors when these form an unstable optical resonator. If paraxial rays launched within such a resonator are confined near the resonator axis, the resonator is termed stable; otherwise it is termed unstable, and is known to have high losses. Siegman has recently presented a geometrical method, brilliantly constructed ad hoc, for calculating these losses in unstable resonators, and indicated where these might be advantageous in laser application. The ray optical theory presented here, which employs the concept of ray modes in an equivalent beam waveguide, is shown to yield results equivalent to those of Siegman for all cases considered by him. However, being derived from conventional ray optics, the validity of the formulas is independently established, and these formulas are immediately applicable to re-entrant resonators and resonators containing inhomogeneous media. The fractional loss per resonator pass is equal to 1-|lambda(2)|, where |lambda(2)| < this 1 is an eigenvalue of the transfer matrix T, representing the corresponding ray transformation. PMID:20048863

  18. The resonator handbook

    NASA Technical Reports Server (NTRS)

    Cook, Jerry D.; Zhou, Shiliang

    1993-01-01

    The purpose of this work is to extend resonator theory into the region in which the planar mirror is quite small. Results of the theoretical description are then extended to resonator design and experimental arrangements as discussed in further sections of this work. Finally, a discussion of dielectric measurements for small samples is included as a specific application of this work.

  19. The Concept of Resonance

    ERIC Educational Resources Information Center

    Truhlar, Donald G.

    2007-01-01

    A general example of a delocalization system associated with a higher energy than the localized one, which suggests that it is wrong to consider delocalization as equivalent to resonance stabilization, is presented. The meaning of resonance energy as it appears in valence bond theory is described as the lowering of the calculated ground-state…

  20. Developpement d'outils quantitatifs pour le suivi par imagerie TEP/TDM de la reponse a la chimiotherapie et de sa toxicite

    NASA Astrophysics Data System (ADS)

    Croteau, Etienne

    L'objectif de ce projet de doctorat est de developper des outils quantitatifs pour le suivi des traitements de chimiotherapie pour le cancer du sein et de leurs effets cardiotoxiques a l'aide de l'imagerie TEP dynamique. L'analyse cinetique en TEP dynamique permet l'evaluation de parametres biologiques in vivo. Cette analyse peut etre utilise pour caracteriser la reponse tumorale a la chimiotherapie et les effets secondaires nefastes qui peuvent en resulter. Le premier article de cette these decrit la mise au point des techniques d'analyse cinetique qui utilisent la fonction d'entree d'un radiotraceur derive de l'image dynamique. Des corrections de contamination radioactive externe (epanchement) et de l'effet de volume partiel ont ete necessaires pour standardiser l'analyse cinetique et la rendre quantitative. Le deuxieme article porte sur l'evaluation d'un nouveau radiotraceur myocardique. Le 11C-acetoacetate, un nouveau radiotraceur base sur un corps cetonique, a ete compare au 11C-acetate, couramment utilise en imagerie cardiaque TEP. L'utilisation de 3H-acetate et 14C-acetoacetate ont permis d'elucider la cinetique de ces traceurs depuis la fonction d'entree et la captation par les mitochondries cardiaques qui reflete la consommation en oxygene, jusqu'a la liberation de leurs principaux metabolites reciproques (3H20 et 14CO2). Le troisieme et dernier article de cette these presente l'integration d'un modele qui evalue la reserve cardiaque de perfusion et de consommation en oxygene. Un modele de cardiomyopathie a ete etabli a l'aide d'un agent chimiotherapeutique contre le cancer du sein, la doxorubicine, reconnu comme etant cardiotoxique. Un protocole de repos/effort a permis d'evaluer la capacite d'augmentation de perfusion et de consommation en oxygene par le coeur. La demonstration d'une reserve cardiaque reduite caracterise la cardiotoxicite. La derniere contribution de cette these porte sur la mise au point de methodes peu invasives pour mesurer la

  1. PAR2-dependent activation of GSK3β regulates the survival of colon stem/progenitor cells.

    PubMed

    Nasri, Imen; Bonnet, Delphine; Zwarycz, Bailey; d'Aldebert, Emilie; Khou, Sokchea; Mezghani-Jarraya, Raoudha; Quaranta, Muriel; Rolland, Corinne; Bonnart, Chrystelle; Mas, Emmanuel; Ferrand, Audrey; Cenac, Nicolas; Magness, Scott; Van Landeghem, Laurianne; Vergnolle, Nathalie; Racaud-Sultan, Claire

    2016-08-01

    Protease-activated receptors PAR1 and PAR2 play an important role in the control of epithelial cell proliferation and migration. However, the survival of normal and tumor intestinal stem/progenitor cells promoted by proinflammatory mediators may be critical in oncogenesis. The glycogen synthase kinase-3β (GSK3β) pathway is overactivated in colon cancer cells and promotes their survival and drug resistance. We thus aimed to determine PAR1 and PAR2 effects on normal and tumor intestinal stem/progenitor cells and whether they involved GSK3β. First, PAR1 and PAR2 were identified in colon stem/progenitor cells by immunofluorescence. In three-dimensional cultures of murine crypt units or single tumor Caco-2 cells, PAR2 activation decreased numbers and size of normal or cancerous spheroids, and PAR2-deficient spheroids showed increased proliferation, indicating that PAR2 represses proliferation. PAR2-stimulated normal cells were more resistant to stress (serum starvation or spheroid passaging), suggesting prosurvival effects of PAR2 Accordingly, active caspase-3 was strongly increased in PAR2-deficient normal spheroids. PAR2 but not PAR1 triggered GSK3β activation through serine-9 dephosphorylation in normal and tumor cells. The PAR2-triggered GSK3β activation implicates an arrestin/PP2A/GSK3β complex that is dependent on the Rho kinase activity. Loss of PAR2 was associated with high levels of GSK3β nonactive form, strengthening the role of PAR2 in GSK3β activation. GSK3 pharmacological inhibition impaired the survival of PAR2-stimulated spheroids and serum-starved cells. Altogether our data identify PAR2/GSK3β as a novel pathway that plays a critical role in the regulation of stem/progenitor cell survival and proliferation in normal colon crypts and colon cancer. PMID:27313176

  2. Propriétés d'un fil quantique connecté à des fils de mesure

    NASA Astrophysics Data System (ADS)

    Safi, Inès.

    conductance of the clean wire is insensitive to interactions, the Tomonaga-Luttinger model features manifest in the presence of backscattering potential. The leading renormalization equations are derived explicitly at finite temperature for any weak backscattering potential; the developed formalism is suited to any noninvariant translational interactions. The role of impurities is found to be governed by the interactions in the wire, but is affected by the external leads, especially for very repulsive interactions because the tendency towards the Wigner crystal is suppressed at low temperature. The reduction in the conductance R=g- e2 /h has a non-trivial power law behavior. For randomly distributed weak impurities, we compute the conductance fluctuations; the ratio Var(R)/ < R > 2 saturates at 1/2 in the low temperature limit indicating that the relative fluctuations of R increases as one lowers the temperature. Recent remarkable experiments on quantum wires are discussed; the conductance in the ballistic limit seems in accordance with our prediction. Concerning the clean wire, other alternatives of measurement are also discussed. The Kubo formula as a response to the local field is reconsidered in a generic Luttinger liquid: the "intrinsic" conductance thus obtained is found to be determined by the same combination of interaction parameters as that which renormalizes the current. Une nouvelle approche du transport dans un fil quantique est proposée, fondée sur une adaptation de l'approche de diffusion à un fil avec interactions (liquide de Tomonaga-Luttinger). Une équation cinétique est développée, permettant de tenir compte des réservoirs, mais aussi d'obtenir des résultats d'une façon directe. Il est ainsi montré que la conductance DC du fil propre est indépendante des interactions à portée et profil arbitraires, et reste égale à e2/h. Les réservoirs sont simulés par le flux qu'ils injectent, lequel est introduit comme condition aux bords de l

  3. Brulure par Foudre. A Propos d’une Observation

    PubMed Central

    Mradmi, W.; Fassi-Fihri, J.; Mehaji, G.; Ezzoubi, M.; Diouri, M.; Bahechar, N.; Boukind, E.H.

    2005-01-01

    Summary Aussi loin que l’on remonte dans la littérature, on retrouve des récits relatant des accidents consécutifs à la fulguration chez l’homme. La foudre était alors associée à la colère des dieux ou à la notion de châtiment. La fulguration correspond à un transfert d’énergie entre un cumulonimbus de charge négative et un objet de charge positive se trouvant au niveau du sol. Les lésions déterminées sont à la fois thermiques et électrothermiques. Bien que l’arrêt cardiorespiratoire soit une cause bien documentée de décès, la plupart des cas rapportés dans la littérature décrivent un éventail très disparate des séquelles qui surviennent suite à cet accident. Les Auteurs rapportent le cas d’un patient atteint par la foudre en insistant particulièrement sur les complications neurologiques qui sont survenues en cours d’évolution. Se basant sur cette observation et sur une revue de la littérature, les Auteurs soulignent que le pronostic des patients atteints par la foudre est plus favorable que généralement rapporté. PMID:21990993

  4. La prise en charge à long terme de l’asthme chez les enfants inuits et des Premières nations : un outil de transfert du savoir fondé sur les lignes directrices canadiennes pour l’asthme pédiatrique, conçu pour être utilisé par les professionnels de la santé de première ligne qui travaillent dans des communautés isolées

    PubMed Central

    Kovesi, Tom; Giles, Brenda Louise; Pasterkamp, Hans

    L’asthme est un grave problème de santé pour les enfants inuits et des Premières nations. Chez les enfants de moins d’un an, il faut distinguer l’asthme de la bronchiolite virale, anormalement fréquente chez les enfants autochtones du Canada. Chez les enfants de moins de six ans, le diagnostic dépend de la présence de symptômes classiques, de l’absence de caractéristiques atypiques et de la consignation de la réponse au traitement, notamment la réponse rapide et transitoire aux bronchodilatateurs. Chez les enfants plus âgés, il faut, dans la mesure du possible, déterminer la présence d’une obstruction réversible des voies aériennes par spirométrie afin de confirmer le diagnostic, ainsi qu’évaluer et corriger les déclencheurs environnementaux. L’utilisation régulière de corticoïdes en aérosol est la principale mesure à prendre pour maintenir un bon contrôle de l’asthme chez les enfants asthmatiques. Les clients et leur famille devraient recevoir une formation sur l’asthme. Il faut réévaluer régulièrement le contrôle aux visites de suivi dans des centres de santé et rajuster le traitement à la dose la plus basse possible pour le maintien de ce contrôle.

  5. Narrowband resonant transmitter

    DOEpatents

    Hutchinson, Donald P.; Simpson, Marcus L.; Simpson, John T.

    2004-06-29

    A transverse-longitudinal integrated optical resonator (TLIR) is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide. The PBG is positioned between the first and second subwavelength resonant gratings. An electro-optic waveguide material may be used to permit tuning the TLIR and to permit the TLIR to perform signal modulation and switching. The TLIR may be positioned on a bulk substrate die with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a TLIR including fabricating a broadband reflective grating is disclosed. A method for tuning the TLIR's transmission resonance wavelength is also disclosed.

  6. Resonant snubber inverter

    DOEpatents

    Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.

    1997-06-24

    A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.

  7. Resonant snubber inverter

    DOEpatents

    Lai, Jih-Sheng; Young, Sr., Robert W.; Chen, Daoshen; Scudiere, Matthew B.; Ott, Jr., George W.; White, Clifford P.; McKeever, John W.

    1997-01-01

    A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

  8. The polarity protein Par3 regulates APP trafficking and processing through the endocytic adaptor protein Numb.

    PubMed

    Sun, Miao; Asghar, Suwaiba Z; Zhang, Huaye

    2016-09-01

    The processing of amyloid precursor protein (APP) into β-amyloid peptide (Aβ) is a key step in the pathogenesis of Alzheimer's disease (AD), and trafficking dysregulations of APP and its secretases contribute significantly to altered APP processing. Here we show that the cell polarity protein Par3 plays an important role in APP processing and trafficking. We found that the expression of full length Par3 is significantly decreased in AD patients. Overexpression of Par3 promotes non-amyloidogenic APP processing, while depletion of Par3 induces intracellular accumulation of Aβ. We further show that Par3 functions by regulating APP trafficking. Loss of Par3 decreases surface expression of APP by targeting APP to the late endosome/lysosome pathway. Finally, we show that the effects of Par3 are mediated through the endocytic adaptor protein Numb, and Par3 functions by interfering with the interaction between Numb and APP. Together, our studies show a novel role for Par3 in regulating APP processing and trafficking. PMID:27072891

  9. Développement d'outils de mesure pour l'amélioration du procédé d'impression offset

    NASA Astrophysics Data System (ADS)

    Boumaïza, K.; Baudin, G.; Catusse, R.; Viallet, A.

    1999-03-01

    The offset printing process rests primarily on the balance between ink and damping solution. However, this balance remains difficult to realize. The corresponding wastes of time and into consumable (ink, paper and damping solution) are harmful for the industrialist, the consumer and the environment. The main feature of this work is to control and thus to optimize these flux. With this intention, two optical sensors functioning in reflection were developed. A laser with receiving photodiode for the control of damping solution film thickness, and an optical fiber related to a photoelectric sensor for control of ink film thickness. The current study aims at the calibration of these two sensors for respectively the control of water and ink flux in the offset press. Le procédé d'impression offset repose essentiellement sur l'équilibre entre la solution de mouillage et l'encre. Toutefois, cet équilibre reste une tâche difficile à réaliser. Les pertes en temps et en consommables (encre, papier, solution de mouillage) correspondantes sont nuisibles à la fois pour l'industriel, le consommateur et l'environnement. L'objectif de ce travail est de contrôler et donc d'optimiser ces flux pour un tirage donné. Pour ce faire, deux capteurs de type optique fonctionnant en réflexion ont été développés. Un laser avec photodiode réceptrice pour le contrôle du film de solution de mouillage, et une fibre optique liée à un capteur photoélectrique pour le contrôle du film d'encre. L'étude actuelle vise la mise en ouvre et l'étalonnage de ces deux capteurs pour la mesure et le contrôle des films respectifs d'eau et d'encre dans la presse offset.

  10. Common variants in the human platelet PAR4 thrombin receptor alter platelet function and differ by race

    PubMed Central

    Edelstein, Leonard C.; Simon, Lukas M.; Lindsay, Cory R.; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E.; Chen, Edward S.; Ma, Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A.

    2014-01-01

    Human platelets express 2 thrombin receptors: protease-activated receptor (PAR)-1 and PAR4. Recently, we reported 3.7-fold increased PAR4-mediated aggregation kinetics in platelets from black subjects compared with white subjects. We now show that platelets from blacks (n = 70) express 14% more PAR4 protein than those from whites (n = 84), but this difference is not associated with platelet PAR4 function. Quantitative trait locus analysis identified 3 common single nucleotide polymorphisms in the PAR4 gene (F2RL3) associated with PAR4-induced platelet aggregation. Among these single nucleotide polymorphisms, rs773902 determines whether residue 120 in transmembrane domain 2 is an alanine (Ala) or threonine (Thr). Compared with the Ala120 variant, Thr120 was more common in black subjects than in white subjects (63% vs 19%), was associated with higher PAR4-induced human platelet aggregation and Ca2+ flux, and generated greater inositol 1,4,5-triphosphate in transfected cells. A second, less frequent F2RL3 variant, Phe296Val, was only observed in blacks and abolished the enhanced PAR4-induced platelet aggregation and 1,4,5-triphosphate generation associated with PAR4-Thr120. PAR4 genotype did not affect vorapaxar inhibition of platelet PAR1 function, but a strong pharmacogenetic effect was observed with the PAR4-specific antagonist YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole]. These findings may have an important pharmacogenetic effect on the development of new PAR antagonists. PMID:25293779

  11. Modelling resonant planetary systems

    NASA Astrophysics Data System (ADS)

    Emel'yanenko, V.

    2012-09-01

    Many discovered multi-planet systems are in meanmotion resonances. The aim of this work is to study dynamical processes leading to the formation of resonant configurations on the basis of a unified model described earlier [1]. The model includes gravitational interactions of planets and migration of planets due to the presence of a gas disc. For the observed systems 24 Sex, HD 37124, HD 73526, HD 82943, HD 128311, HD 160691, Kepler 9, NN Ser with planets moving in the 2:1 resonance, it is shown that the capture in this resonance occurs at very wide ranges of parameters of both type I and type II migration. Conditions of migration leading to the formation of the resonant systems HD 45364 и HD 200964 (3:2 and 4:3, respectively) are obtained. Formation scenarios are studied for the systems HD 102272, HD 108874, HD 181433, HD 202206 with planets in high order resonances. We discuss also how gravitational interactions of planets and planetesimal discs lead to the breakup of resonant configurations and the formation of systems similar to the 47 UMa system.

  12. LABCOM resonator Phase 3

    SciTech Connect

    Keres, L.J.

    1990-11-01

    The purpose of this project was to develop quartz crystal resonator designs, production processes, and test capabilities for 5-MHz, 6.2-MHz, and 10-MHz resonators for Tactical Miniature Crystal Oscillator (TMXO) applications. GE Neutron Devices (GEND) established and demonstrated the capability to produce and test quartz crystal resonators for use in the TMXO developed by the US Army ERADCOM (now LABCOM). The goals in this project were based on the ERADCOM statement of work. The scope of work indicated that the resonator production facilities for this project would not be completely independent, but that they would be supported in part by equipment and processes in place at GEND used in US Department of Energy (DOE) work. In addition, provisions for production test equipment or or eventual technology transfer costs to a commercial supplier were clearly excluded from the scope of work. The demonstrated technical capability of the deep-etched blank design is feasible and practical. It can be manufactured in quantity with reasonable yield, and its performance is readily predictable. The ceramic flatpack is a very strong package with excellent hermeticity. The four-point mount supports the crystal to reasonable shock levels and does not perturb the resonator's natural frequency-temperature behavior. The package can be sealed with excellent yields. The high-temperature, high-vacuum processing developed for the TMXO resonator, including bonding the piezoid to its mount with conductive polyimide adhesive, is consistent with precision resonator fabrication. 1 fig., 6 tabs.

  13. Spin resonance strength calculations

    SciTech Connect

    Courant,E.D.

    2008-10-06

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  14. Tunable multiwalled nanotube resonator

    DOEpatents

    Zettl, Alex K.; Jensen, Kenneth J.; Girit, Caglar; Mickelson, William E.; Grossman, Jeffrey C.

    2011-03-29

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  15. Tunable multiwalled nanotube resonator

    DOEpatents

    Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C

    2013-11-05

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  16. Activation of protease-activated receptors (PARs)-1 and -2 promotes alpha-smooth muscle actin expression and release of cytokines from human lung fibroblasts

    PubMed Central

    Asokananthan, Nithiananthan; Lan, Rommel S; Graham, Peter T; Bakker, Anthony J; Tokanović, Ana; Stewart, Geoffrey A

    2015-01-01

    Previous studies have shown that protease-activated receptors (PARs) play an important role in various physiological processes. In the present investigation, we determined the expression of PARs on human lung fibroblasts (HLF-1) and whether they were involved in cellular differentiation and pro-inflammatory cytokine and prostaglandin (PGE2) secretion. PAR-1, PAR-2, PAR-3, and PAR-4 were detected in fibroblasts using RT-PCR, immunocytochemistry, and flow cytometry. Increased expression of PAR-4, but not other PARs, was observed in fibroblasts stimulated with phorbol myristate acetate. The archetypical activators of PARs, namely, thrombin and trypsin, as well as PAR-1 and PAR-2 agonist peptides, stimulated transient increases in intracellular Ca2+, and promoted increased α-smooth muscle actin expression. The proteolytic and peptidic PAR activators also stimulated the release of IL-6 and IL-8, as well as PGE2, with a rank order of potency of PAR-1 > PAR-2. The combined stimulation of PAR-1 and PAR-2 resulted in an additive release of both IL-6 and IL-8. In contrast, PAR-3 and PAR-4 agonist peptides, as well as all the PAR control peptides examined, were inactive. These results suggest an important role for PARs associated with fibroblasts in the modulation of inflammation and remodeling in the airway. PMID:25663523

  17. Secreted uPAR isoform 2 (uPAR7b) is a novel direct target of miR-221.

    PubMed

    Falkenberg, Natalie; Anastasov, Nataša; Schaub, Annalisa; Radulovic, Vanja; Schmitt, Manfred; Magdolen, Viktor; Aubele, Michaela

    2015-04-10

    miR-221/-222 and components of the urokinase-type plasminogen activator system (uPAS) are associated with metastasis and poor prognosis in breast cancer, including the triple-negative subtype (TNBC). Modification of components of uPAS and involved miRNAs may contribute to targeted therapy for breast cancer patients. miR-221-/-222-overexpressing or miR-221-depleted cells were employed for qRT-PCR and Western blots to show associations of uPAR with miR-221/-222. To substantiate direct targeting of miR-221/-222 within 3' UTR of the uPAR isoform 2, in silico analysesand in vitro assays were conducted. Significant associations between miR-221 and uPAR isoform 2 expressions were observed at the mRNA and protein levels in breast cancer cells representing TNBC. For the first time, the uPAR isoform 2 was demonstrated as direct target for miR-221/-222. Inhibition of miR-221 reduced uPAR protein expression and expression of the tumor cell invasion markers vimentin and RHOC. These results demonstrate a direct and positive regulation of the secreted uPAR isoform 2 by miR-221, increasing its protein expression, a prerequisite for malignancy, while the other uPAR isoforms (1, 3 and 4) are indirectly regulated through miR-10b and miR-221/-222. By targeting uPAR isoforms and/or miRNA-221/-222, the diagnosis and therapy of breast cancer, in particular in TNBC, could be significantly improved. PMID:25797271

  18. Détermination du module d'Young dans des films minces de tungstène par diffraction des rayons X

    NASA Astrophysics Data System (ADS)

    Villain, P.; Goudeau, P.; Renault, P.-O.; Badawi, K. F.

    2002-07-01

    Elasticity of reduced dimension materials remains misunderstood since both experimental and theoretical studies on this subject are difficult to perform. Numerous experiments realised in the early 90's evidenced “elastic anomalies” in small period multilayer systems: “supermodulus”, breakdown of the Poisson's effect. The polemic raised by these observations lead us to develop a method to study the elastic constants in thin films on substrates; it combines X-ray diffraction and in situ tensile testing. This paper presents results on Poisson's ratio and Young's modulus measurement in 140nmW thin films; the obtained Young's modulus was smaller to the bulk material one whereas the Poisson's ratio was significantly larger than the bulk one. L'élasticité des matériaux de faible dimension demeure encore méconnue. Ceci tient entre autre à la difficulté de l'approche expérimentale et théorique. Dans les années 90, un grand nombre d'expériences ont mis en évidence des anomalies élastiques dans des systèmes multicouches de très faible période : supermodule, déviation à la loi de Poisson. La polémique soulevée par ces observations nous a amené à développer une méthode d'étude des constantes d'élasticité module d'Young et coefficient de Poisson dans les films minces sur substrats; elle combine la diffraction des rayons X et la déformation in situ. Cet article présente les résultats obtenus dans le cas de films de tungstène de 140nm d'épaisseur; la valeur mesurée pour le module d'Young est inférieure à celle du même matériau à l'état massif alors que pour le coefficient de Poisson, la valeur est plus grande.

  19. Poly (ADP-ribose) (PAR) Binding to Apoptosis-Inducing Factor Is Critical For PAR Polymerase-1-Dependent Cell Death (Parthanatos)

    PubMed Central

    Wang, Yingfei; Kim, No Soo; Haince, Jean-Francois; Kang, HoChul; David, Karen K.; Andrabi, Shaida A.; Poirier, Guy G.; Dawson, Valina L.; Dawson, Ted M.

    2011-01-01

    The mitochondrial protein apoptosis-inducing factor (AIF) plays a pivotal role in poly(ADP-ribose) polymerase-1 (PARP-1)-mediated cell death (parthanatos), during which it is released from the mitochondria and translocates to the nucleus. Here, we show that AIF is a high affinity poly(ADP-ribose) (PAR)–binding protein and that PAR binding to AIF is required for parthanatos both in vitro and in vivo. AIF bound PAR at a site distinct from AIF’s DNA binding site and this interaction triggered AIF release from the cytosolic side of the mitochondrial outer membrane. Mutation of the PAR binding site in AIF did not affect its NADH oxidase activity, its ability to bind FAD or DNA, or its ability to induce nuclear condensation. However, this AIF mutant was not released from mitochondria and did not translocate to the nucleus or mediate cell death following PARP-1 activation. These results suggest a mechanism for PARP-1 to initiate AIF-mediated cell death and indicate that AIF’s bioenergetic cell survival-promoting functions are separate from its effects as a mitochondrially-derived death effector. Interference with the PAR-AIF interaction or PAR signaling may provide unique opportunities for preventing cell death following activation of PARP-1. PMID:21467298

  20. Clinical outcomes of pars plicata anterior vitrectomy: 2-year results

    PubMed Central

    Narang, Priya; Agarwal, Amar

    2015-01-01

    Purpose: To demonstrate the safety and outcome of a surgical approach that uses pars plicata site for anterior vitrectomy during phacoemulsification procedure complicated by posterior capsule rupture and residual cortical matter. Design: Single center, retrospective, interventional, noncomparative study. Materials and Methods: Medical records of a consecutive series of 35 eyes of 35 patients who underwent pars plicata anterior vitrectomy (PPAV) were reviewed. The main outcome measures were corrected and uncorrected distance visual acuity (CDVA, UDVA), early and late postoperative complications and intraocular pressure (IOP). Ultrasound biomicroscopic (UBM) evaluation of sclerotomy site and spectral domain optical coherence tomography analysis for central macular thickness (CMT) was performed. The final visual outcome at 2 years was evaluated. Results: At 2 years follow-up, the mean postoperative UDVA (logarithm of the minimum angle of resolution [logMAR]) and CDVA (logMAR) was 0.49 ± 0.26 and 0.19 ± 0.14, respectively. There was no significant change in the IOP (P = 0.061) and the mean CMT at 2 years was 192.5 ± 5.54 μm. The postoperative UBM image of the sclerotomy site at 8 weeks demonstrated a clear wound without any vitreous adhesion or incarceration. Intraoperative hyphema was seen in 1 (2.8%) case and postoperative uveitis was seen in 2 (5.7%) cases, which resolved with medications. No case of an iatrogenic retinal break or retinal detachment was reported. Conclusions: PPAV enables a closed chamber approach, allows thorough cleanup of vitreous in the pupillary plane and anterior chamber and affords better access to the subincisional and retropupillary cortical remnant with a significant visual outcome and an acceptable complication rate. PMID:26632124

  1. Micro-machined resonator

    DOEpatents

    Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

    1993-03-30

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  2. Micro-machined resonator

    DOEpatents

    Godshall, Ned A.; Koehler, Dale R.; Liang, Alan Y.; Smith, Bradley K.

    1993-01-01

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  3. Resonances in QCD

    NASA Astrophysics Data System (ADS)

    Lutz, Matthias F. M.; Lange, Jens Sören; Pennington, Michael; Bettoni, Diego; Brambilla, Nora; Crede, Volker; Eidelman, Simon; Gillitzer, Albrecht; Gradl, Wolfgang; Lang, Christian B.; Metag, Volker; Nakano, Takashi; Nieves, Juan; Neubert, Sebastian; Oka, Makoto; Olsen, Stephen L.; Pappagallo, Marco; Paul, Stephan; Pelizäus, Marc; Pilloni, Alessandro; Prencipe, Elisabetta; Ritman, Jim; Ryan, Sinead; Thoma, Ulrike; Uwer, Ulrich; Weise, Wolfram

    2016-04-01

    We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14, 2015. A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions: What is needed to understand the physics of resonances in QCD? Where does QCD lead us to expect resonances with exotic quantum numbers? What experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy-light and heavy-heavy meson systems, those with charm quarks were the focus. This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

  4. Resonant ultrasound spectroscopy

    DOEpatents

    Migliori, Albert

    1991-01-01

    A resonant ultrasound spectroscopy method provides a unique characterization of an object for use in distinguishing similar objects having physical differences greater than a predetermined tolerance. A resonant response spectrum is obtained for a reference object by placing excitation and detection transducers at any accessible location on the object. The spectrum is analyzed to determine the number of resonant response peaks in a predetermined frequency interval. The distribution of the resonance frequencies is then characterized in a manner effective to form a unique signature of the object. In one characterization, a small frequency interval is defined and stepped though the spectrum frequency range. Subsequent objects are similarly characterized where the characterizations serve as signatures effective to distinguish objects that differ from the reference object by more than the predetermined tolerance.

  5. Resonances in Positronium Hydride

    NASA Technical Reports Server (NTRS)

    DiRienzi, Joseph; Drachman, Richard J.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We re-examine the problem of calculating the positions and widths of the lowest-lying resonances in the Ps + H scattering system which consists of two electrons, one positron and one proton. The first of these resonances, for L=0, was found by the methods of complex rotation and stabilization, and later described as a Feshbach resonance lying close to a bound state in the closed-channel e (+) + H (-) system. Recently, results for the L=1 and 2 scattering states were published, and it was found, surprisingly, that there is a larae shift in the positions of these resonances. In this work we repeat the analysis for L=1 and find an unexpected explanation for the shift.

  6. Solar PAR and UVR modify the community composition and photosynthetic activity of sea ice algae.

    PubMed

    Enberg, Sara; Piiparinen, Jonna; Majaneva, Markus; Vähätalo, Anssi V; Autio, Riitta; Rintala, Janne-Markus

    2015-10-01

    The effects of increased photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) on species diversity, biomass and photosynthetic activity were studied in fast ice algal communities. The experimental set-up consisted of nine 1.44 m(2) squares with three treatments: untreated with natural snow cover (UNT), snow-free (PAR + UVR) and snow-free ice covered with a UV screen (PAR). The total algal biomass, dominated by diatoms and dinoflagellates, increased in all treatments during the experiment. However, the smaller biomass growth in the top 10-cm layer of the PAR + UVR treatment compared with the PAR treatment indicated the negative effect of UVR. Scrippsiella complex (mainly Scrippsiella hangoei, Biecheleria baltica and Gymnodinium corollarium) showed UV sensitivity in the top 5-cm layer, whereas Heterocapsa arctica ssp. frigida and green algae showed sensitivity to both PAR and UVR. The photosynthetic activity was highest in the top 5-cm layer of the PAR treatment, where the biomass of the pennate diatom Nitzschia frigida increased, indicating the UV sensitivity of this species. This study shows that UVR is one of the controlling factors of algal communities in Baltic Sea ice, and that increased availability of PAR together with UVR exclusion can cause changes in algal biomass, photosynthetic activity and community composition. PMID:26310455

  7. The parA resolvase performs site-specific genomic excision in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have designed a site-specific excision detection system in Arabidopsis to study the in planta activity of the small serine recombinase ParA. Using a transient expression assay as well as stable transgenic plant lines, we show that the ParA recombinase is catalytically active and capable of perfo...

  8. Targeting Melanoma Growth and Metastasis with Systemic Delivery of Liposomal Incorporated PAR-1 siRNA

    PubMed Central

    Villares, Gabriel J.; Zigler, Maya; Wang, Hua; Melnikova, Vladislava O.; Wu, Hong; Friedman, Ran; Leslie, Michael C.; Vivas-Mejia, Pablo E.; Lopez-Berestein, Gabriel; Sood, Anil K.; Bar-Eli, Menashe

    2008-01-01

    The thrombin receptor (PAR-1, Protease-Activated-Receptor-1) is over-expressed in highly metastatic melanoma cell lines and in patients with metastatic lesions. Activation of PAR-1 leads to cell signaling and upregulation of genes involved in adhesion, invasion and angiogenesis. Herein, we stably silence PAR-1 through the use of lentiviral shRNA and found significant decreases in both tumor growth (P<.01) and metastasis (P<.001) of highly metastatic melanoma cell lines in vivo. The use of viruses for therapy is not ideal as it can induce toxic immune responses and possible gene alterations following viral integration. Therefore, we also utilized systemic delivery of PAR-1 siRNA incorporated into neutral liposomes (DOPC) to decrease melanoma growth and metastasis in vivo. Significant decreases in tumor growth, weight and metastatic lung colonies (P<.001 for all) were found in mice treated with PAR-1-siRNA-DOPC. The in vivo effects of PAR-1 on invasion and angiogenesis were analyzed via immunohistochemistry. Concomitant decreases in VEGF, IL-8, and MMP-2 expression levels, as well as decreased blood-vessel density (CD31), were found in tumor samples from PAR-1 siRNA-treated mice, suggesting that PAR-1 is a regulator of melanoma cell growth and metastasis by affecting angiogenic and invasive factors. We propose that siRNA incorporated into DOPC nanoparticles could be delivered systemically and used as a new modality for melanoma treatment. PMID:18974154

  9. 12 CFR 925.19 - Par value and price of stock.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Par value and price of stock. 925.19 Section 925.19 Banks and Banking FEDERAL HOUSING FINANCE BOARD FEDERAL HOME LOAN BANK MEMBERS AND HOUSING ASSOCIATES MEMBERS OF THE BANKS Stock Requirements § 925.19 Par value and price of stock. The capital...

  10. Participatory Action Research (PAR) cum Action Research (AR) in Teacher Professional Development: A Literature Review

    ERIC Educational Resources Information Center

    Morales, Marie Paz E.

    2016-01-01

    This paper reviews Participatory Action Research as an approach to teacher professional development. It maps the origins of Participatory Action Research (PAR) and discusses the benefits and challenges that have been identified by other researchers in utilizing PAR approaches in conducting research. It draws ideas of combining the features of…