WorldWideScience

Sample records for opposed jet extinction

  1. Unsteady Extinction of Opposed Jet Ethylene/Methane HIFiRE Surrogate Fuel Mixtures vs Air

    Science.gov (United States)

    Vaden, Sarah N.; Debes, Rachel L.; Lash, E. Lara; Burk, Rachel S.; Boyd, C. Merritt; Wilson, Lloyd G.; Pellett, Gerald L.

    2009-01-01

    A unique idealized study of the subject fuel vs. air systems was conducted using an Oscillatory-input Opposed Jet Burner (OOJB) system and a newly refined analysis. Extensive dynamic-extinction measurements were obtained on unanchored (free-floating) laminar Counter Flow Diffusion Flames (CFDFs) at 1-atm, stabilized by steady input velocities (e.g., U(sub air)) and perturbed by superimposed in-phase sinusoidal velocity inputs at fuel and air nozzle exits. Ethylene (C2H4) and methane (CH4), and intermediate 64/36 and 15/85 molar percent mixtures were studied. The latter gaseous surrogates were chosen earlier to mimic ignition and respective steady Flame Strengths (FS = U(sub air)) of vaporized and cracked, and un-cracked, JP-7 "like" kerosene for a Hypersonic International Flight Research Experimentation (HIFiRE) scramjet. For steady idealized flameholding, the 100% C2H4 flame is respectively approx. 1.3 and approx.2.7 times stronger than a 64/36 mix and CH4; but is still 12.0 times weaker than a 100% H2-air flame. Limited Hot-Wire (HW) measurements of velocity oscillations at convergent-nozzle exits, and more extensive Probe Microphone (PM) measurements of acoustic pressures, were used to normalize Dynamic FSs, which decayed linearly with pk/pk U(sub air) (velocity magnitude, HW), and also pk/pk P (pressure magnitude, PM). Thus Dynamic Flame Weakening (DFW) is defined as % decrease in FS per Pascal of pk/pk P oscillation, namely, DFW = -100 d(U(sub air)/U(sub air),0Hz)/d(pkpk P). Key findings are: (1) Ethylene flames are uniquely strong and resilient to extinction by oscillating inflows below 150 Hz; (2) Methane flames are uniquely weak; (3) Ethylene / methane surrogate flames are disproportionately strong with respect to ethylene content; and (4) Flame weakening is consistent with limited published results on forced unsteady CFDFs. Thus from 0 to approx. 10 Hz and slightly higher, lagging diffusive responses of key species led to progressive phase lags (relative

  2. Numerical and experimental study of two turbulent opposed plane jets

    Energy Technology Data Exchange (ETDEWEB)

    Besbes, Sonia; Mhiri, Hatem [Laboratoire de Mecanique des Fluides et Thermique, Ecole Nationale d' Ingenieurs de Monastir, Route de Ouardanine, Monastir (Tunisia); Le Palec, Georges; Bournot, Philippe [Institut de Mecanique de Marseille, UNIMECA, Technopole de Chateau-Gombert, 60 rue Joliot-Curie, 13453 Marseille (France)

    2003-09-01

    The turbulent interaction between two opposed plane jets separated by a distance H is experimentally studied by using a PIV (Particle Image Velocimetry) method and numerically investigated by means of a finite volume code. Two turbulence models have been tested: the standard k-{epsilon} model and a second-order model. The validation of the numerical study was performed by comparing the results with experimental data obtained for the case of two interacting opposed jets at ambient temperature (isothermal case). The effect of the angle of inclination of the jets is studied. Conclusions of the validation are then used to study the interaction between two jets, one being maintained at ambient temperature whereas the other is heated. Results show that the stagnation point moves towards the heated jet. It is shown that the heating induces a stabilizing effect on the flow. (orig.)

  3. Re: Penetration Behavior of Opposed Rows of Staggered Secondary Air Jets Depending on Jet Penetration Coefficient and Momentum Flux Ratio

    Science.gov (United States)

    Holdeman, James D.

    2016-01-01

    The purpose of this article is to explain why the extension of the previously published C = (S/Ho)sqrt(J) scaling for opposed rows of staggered jets wasn't directly successful in the study by Choi et al. (2016). It is not surprising that staggered jets from opposite sides do not pass each other at the expected C value, because Ho/D and sqrt(J) are much larger than the maximum in previous studies. These, and large x/D's, tend to suggest development of 2-dimensional flow. Although there are distinct optima for opposed rows of in-line jets, single-side injection, and opposed rows of staggered jets based on C, opposed rows of staggered jets provide as good or better mixing performance, at any C value, than opposed rows of in-line jets or jets from single-side injection.

  4. A new method of thermal protection by opposing jet for a hypersonic aeroheating strut

    Science.gov (United States)

    Qin, Jiang; Ning, Dongpo; Feng, Yu; Zhang, Junlong; Feng, Shuo; Bao, Wen

    2017-06-01

    This paper presents the numerical investigation of thermal protection of scramjet strut by opposing jet in supersonic stream of Mach number 6 with a hydrogen fueled scramjet strut model using CFD software. Simulation results indicate that when a small amount of fuel is injected from the nose of the strut, the bow shock is pushed away from the strut, and the heat flux is reduced in the strut, especially at the leading edge. Opposing jet forms a recirculation region near the nozzle so that the strut is covered with low temperature fuel and separated from free stream. An appropriate total pressure ratio can be used to reduce not only aerodynamic heating but also the drag of strut. It is therefore concluded that thermal protection of scramjet strut by opposing jet is one of the promising ways to protect scramjet strut in high enthalpy stream.

  5. Effects of confinement, geometry, inlet velocity profile, and Reynolds number on the asymmetry of opposed-jet flows

    Science.gov (United States)

    Ansari, Abtin; Chen, Kevin K.; Burrell, Robert R.; Egolfopoulos, Fokion N.

    2018-04-01

    The opposed-jet counterflow configuration is widely used to measure fundamental flame properties that are essential targets for validating chemical kinetic models. The main and key assumption of the counterflow configuration in laminar flame experiments is that the flow field is steady and quasi-one-dimensional. In this study, experiments and numerical simulations were carried out to investigate the behavior and controlling parameters of counterflowing isothermal air jets for various nozzle designs, Reynolds numbers, and surrounding geometries. The flow field in the jets' impingement region was analyzed in search of instabilities, asymmetries, and two-dimensional effects that can introduce errors when the data are compared with results of quasi-one-dimensional simulations. The modeling involved transient axisymmetric numerical simulations along with bifurcation analysis, which revealed that when the flow field is confined between walls, local bifurcation occurs, which in turn results in asymmetry, deviation from the one-dimensional assumption, and sensitivity of the flow field structure to boundary conditions and surrounding geometry. Particle image velocimetry was utilized and results revealed that for jets of equal momenta at low Reynolds numbers of the order of 300, the flow field is asymmetric with respect to the middle plane between the nozzles even in the absence of confining walls. The asymmetry was traced to the asymmetric nozzle exit velocity profiles caused by unavoidable imperfections in the nozzle assembly. The asymmetry was not detectable at high Reynolds numbers of the order of 1000 due to the reduced sensitivity of the flow field to boundary conditions. The cases investigated computationally covered a wide range of Reynolds numbers to identify designs that are minimally affected by errors in the experimental procedures or manufacturing imperfections, and the simulations results were used to identify conditions that best conform to the assumptions of

  6. Numerical analysis of the air chemical non-equilibrium effect in combustion for a semi-sphere with opposing jet

    Science.gov (United States)

    Zhao, Fa-Ming; Wang, Jiang-Feng; Li, Long-Fei

    2018-05-01

    The air chemical non-equilibrium effect (ACNEE) on hydrogen-air combustion flow fields at Mach number of 10 is numerically analyzed for a semi-sphere with a sonic opposing-hydrogen jet. The 2D axisymmetric multi-components N-S equations are solved by using the central scheme with artificial dissipation and the S-A turbulence model. Numerical results show that as compared to the result without ACNEE, the ACNEE has little influence on the structure of flow field, but has a considerable impact on fluid characteristics which reduces the maximum value of mass fraction of water in the flow field and increases the maximum value of mass fraction of water on solid surface, as well as the maximum surface temperature.

  7. COMPARISON OF EXPERIMENTS TO CFD MODELS FOR MIXING USING DUAL OPPOSING JETS IN TANKS WITH AND WITHOUT INTERNAL OBSTRUCTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Leishear, R.; Poirier, M.; Lee, S.; Fowley, M.

    2012-06-26

    This paper documents testing methods, statistical data analysis, and a comparison of experimental results to CFD models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an eight foot diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors such as turbulence, pump fluctuations, and eddies required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations -- or scatter -- occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times were shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy, and determined statistical correction factors that can be applied to CFD models, and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design, and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending, using a pump with dual opposing jets which re-circulate fluids in the tank to promote blending when fluids are added to the tank. In all, eighty-five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full scale, liquid radioactive waste storage tank. Also, different jet

  8. Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal- and micro-gravity

    KAUST Repository

    Hu, Longhua; Lu, Yong; Yoshioka, Kosuke; Zhang, Yangshu; Fernandez-Pello, Carlos; Chung, Suk-Ho; Fujita, Osamu

    2016-01-01

    . The experiments reported here used polyethylene (PE)-insulated (thickness of 0.15 mm) Nichrome (NiCr)-core (diameter of 0.5 mm) electrical wires. Limiting oxygen concentrations (LOC) at extinction were measured for upward spreading flame at various forced opposed-flow

  9. Near-field local flame extinction of Oxy-Syngas non-premixed jet flames : a DNS study

    NARCIS (Netherlands)

    Ranga Dinesh, K.K.J.; Oijen, van J.A.; Luo, Kai; Jiang, X.

    2014-01-01

    An investigation of the local flame extinction of H2/CO oxy-syngas and syngas-air nonpremixed jet flames was carried out using three-dimensional direct numerical simulations (DNS) with detailed chemistry by using flamelet generated manifold chemistry (FGM). The work has two main objectives: identify

  10. A study of performance parameters on drag and heat flux reduction efficiency of combinational novel cavity and opposing jet concept in hypersonic flows

    Science.gov (United States)

    Sun, Xi-wan; Guo, Zhen-yun; Huang, Wei; Li, Shi-bin; Yan, Li

    2017-02-01

    The drag reduction and thermal protection system applied to hypersonic re-entry vehicles have attracted an increasing attention, and several novel concepts have been proposed by researchers. In the current study, the influences of performance parameters on drag and heat reduction efficiency of combinational novel cavity and opposing jet concept has been investigated numerically. The Reynolds-average Navier-Stokes (RANS) equations coupled with the SST k-ω turbulence model have been employed to calculate its surrounding flowfields, and the first-order spatially accurate upwind scheme appears to be more suitable for three-dimensional flowfields after grid independent analysis. Different cases of performance parameters, namely jet operating conditions, freestream angle of attack and physical dimensions, are simulated based on the verification of numerical method, and the effects on shock stand-off distance, drag force coefficient, surface pressure and heat flux distributions have been analyzed. This is the basic study for drag reduction and thermal protection by multi-objective optimization of the combinational novel cavity and opposing jet concept in hypersonic flows in the future.

  11. Search for jet extinction in the inclusive jet-$p_T$ spectrum from proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    CERN Document Server

    Khachatryan, Vardan; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Luyckx, Sten; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Daci, Nadir; Heracleous, Natalie; Kalogeropoulos, Alexis; Keaveney, James; Kim, Tae Jeong; Lowette, Steven; Maes, Michael; Olbrechts, Annik; Python, Quentin; Strom, Derek; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Dobur, Didar; Favart, Laurent; Gay, Arnaud; Grebenyuk, Anastasia; Léonard, Alexandre; Mohammadi, Abdollah; Perniè, Luca; Reis, Thomas; Seva, Tomislav; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Benucci, Leonardo; Cimmino, Anna; Costantini, Silvia; Crucy, Shannon; Dildick, Sven; Fagot, Alexis; Garcia, Guillaume; Klein, Benjamin; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Salva Diblen, Sinem; Sigamani, Michael; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Beluffi, Camille; Bruno, Giacomo; Castello, Roberto; Caudron, Adrien; Ceard, Ludivine; Da Silveira, Gustavo Gil; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Liao, Junhui; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Popov, Andrey; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; Dos Reis Martins, Thiago; Pol, Maria Elena; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Malbouisson, Helena; Malek, Magdalena; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santaolalla, Javier; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Aleksandrov, Aleksandar; Genchev, Vladimir; Iaydjiev, Plamen; Marinov, Andrey; Piperov, Stefan; Rodozov, Mircho; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Du, Ran; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Plestina, Roko; Tao, Junquan; Wang, Xianyou; Wang, Zheng; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Yifei; Li, Qiang; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Zhang, Linlin; Zou, Wei; Avila, Carlos; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Kadija, Kreso; Luetic, Jelena; Mekterovic, Darko; Sudic, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Bodlak, Martin; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Elgammal, Sherif; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Murumaa, Marion; Raidal, Martti; Tiko, Andres; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Nayak, Aruna; Rander, John; Rosowsky, André; Titov, Maksym; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Charlot, Claude; Dahms, Torsten; Dalchenko, Mykhailo; Dobrzynski, Ludwik; Filipovic, Nicolas; Florent, Alice; Granier de Cassagnac, Raphael; Mastrolorenzo, Luca; Miné, Philippe; Mironov, Camelia; Naranjo, Ivo Nicolas; Nguyen, Matthew; Ochando, Christophe; Paganini, Pascal; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Veelken, Christian; Yilmaz, Yetkin; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Aubin, Alexandre; Bloch, Daniel; Brom, Jean-Marie; Chabert, Eric Christian; Collard, Caroline; Conte, Eric; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Goetzmann, Christophe; Le Bihan, Anne-Catherine; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Beaupere, Nicolas; Boudoul, Gaelle; Brochet, Sébastien; Carrillo Montoya, Camilo Andres; Chasserat, Julien; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fan, Jiawei; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Ille, Bernard; Kurca, Tibor; Lethuillier, Morgan; Mirabito, Laurent; Perries, Stephane; Ruiz Alvarez, José David; Sabes, David; Sgandurra, Louis; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Xiao, Hong; Tsamalaidze, Zviad; Autermann, Christian; Beranek, Sarah; Bontenackels, Michael; Calpas, Betty; Edelhoff, Matthias; Feld, Lutz; Hindrichs, Otto; Klein, Katja; Ostapchuk, Andrey; Perieanu, Adrian; Raupach, Frank; Sammet, Jan; Schael, Stefan; Sprenger, Daniel; Weber, Hendrik; Wittmer, Bruno; Zhukov, Valery; Ata, Metin; Caudron, Julien; Dietz-Laursonn, Erik; Duchardt, Deborah; Erdmann, Martin; Fischer, Robert; Güth, Andreas; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Klingebiel, Dennis; Knutzen, Simon; Kreuzer, Peter; Merschmeyer, Markus; Meyer, Arnd; Olschewski, Mark; Padeken, Klaas; Papacz, Paul; Reithler, Hans; Schmitz, Stefan Antonius; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Weber, Martin; Cherepanov, Vladimir; Erdogan, Yusuf; Flügge, Günter; Geenen, Heiko; Geisler, Matthias; Haj Ahmad, Wael; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Kuessel, Yvonne; Lingemann, Joschka; Nowack, Andreas; Nugent, Ian Michael; Perchalla, Lars; Pooth, Oliver; Stahl, Achim; Asin, Ivan; Bartosik, Nazar; Behr, Joerg; Behrenhoff, Wolf; Behrens, Ulf; Bell, Alan James; Bergholz, Matthias; Bethani, Agni; Borras, Kerstin; Burgmeier, Armin; Cakir, Altan; Calligaris, Luigi; Campbell, Alan; Choudhury, Somnath; Costanza, Francesco; Diez Pardos, Carmen; Dooling, Samantha; Dorland, Tyler; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Flucke, Gero; Garay Garcia, Jasone; Geiser, Achim; Gunnellini, Paolo; Hauk, Johannes; Hellwig, Gregor; Hempel, Maria; Horton, Dean; Jung, Hannes; Kasemann, Matthias; Katsas, Panagiotis; Kieseler, Jan; Kleinwort, Claus; Krücker, Dirk; Lange, Wolfgang; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Lutz, Benjamin; Mankel, Rainer; Marfin, Ihar; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mnich, Joachim; Mussgiller, Andreas; Naumann-Emme, Sebastian; Novgorodova, Olga; Nowak, Friederike; Ntomari, Eleni; Perrey, Hanno; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Ribeiro Cipriano, Pedro M; Ron, Elias; Sahin, Mehmet Özgür; Salfeld-Nebgen, Jakob; Saxena, Pooja; Schmidt, Ringo; Schoerner-Sadenius, Thomas; Schröder, Matthias; Spannagel, Simon; Vargas Trevino, Andrea Del Rocio; Walsh, Roberval; Wissing, Christoph; Aldaya Martin, Maria; Blobel, Volker; Centis Vignali, Matteo; Erfle, Joachim; Garutti, Erika; Goebel, Kristin; Görner, Martin; Gosselink, Martijn; Haller, Johannes; Höing, Rebekka Sophie; Kirschenmann, Henning; Klanner, Robert; Kogler, Roman; Lange, Jörn; Lapsien, Tobias; Lenz, Teresa; Marchesini, Ivan; Ott, Jochen; Peiffer, Thomas; Pietsch, Niklas; Rathjens, Denis; Sander, Christian; Schettler, Hannes; Schleper, Peter; Schlieckau, Eike; Schmidt, Alexander; Seidel, Markus; Poehlsen, Jennifer; Sola, Valentina; Stadie, Hartmut; Steinbrück, Georg; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Barth, Christian; Baus, Colin; Berger, Joram; Böser, Christian; Butz, Erik; Chwalek, Thorsten; De Boer, Wim; Descroix, Alexis; Dierlamm, Alexander; Feindt, Michael; Hartmann, Frank; Hauth, Thomas; Husemann, Ulrich; Katkov, Igor; Kornmayer, Andreas; Kuznetsova, Ekaterina; Lobelle Pardo, Patricia; Mozer, Matthias Ulrich; Müller, Thomas; Nürnberg, Andreas; Quast, Gunter; Rabbertz, Klaus; Ratnikov, Fedor; Röcker, Steffen; Simonis, Hans-Jürgen; Stober, Fred-Markus Helmut; Ulrich, Ralf; Wagner-Kuhr, Jeannine; Wayand, Stefan; Weiler, Thomas; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Markou, Athanasios; Markou, Christos; Psallidas, Andreas; Topsis-Giotis, Iasonas; Gouskos, Loukas; Panagiotou, Apostolos; Saoulidou, Niki; Stiliaris, Efstathios; Aslanoglou, Xenofon; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Bencze, Gyorgy; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Molnar, Jozsef; Palinkas, Jozsef; Szillasi, Zoltan; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Swain, Sanjay Kumar; Beri, Suman Bala; Bhatnagar, Vipin; Dhingra, Nitish; Gupta, Ruchi; Kalsi, Amandeep Kaur; Kaur, Manjit; Mittal, Monika; Nishu, Nishu; Singh, Jasbir; Kumar, Ashok; Kumar, Arun; Ahuja, Sudha; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Varun; Banerjee, Sunanda; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dutta, Suchandra; Gomber, Bhawna; Jain, Sandhya; Jain, Shilpi; Khurana, Raman; Modak, Atanu; Mukherjee, Swagata; Roy, Debarati; Sarkar, Subir; Sharan, Manoj; Abdulsalam, Abdulla; Dutta, Dipanwita; Kailas, Swaminathan; Kumar, Vineet; Mohanty, Ajit Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Banerjee, Sudeshna; Chatterjee, Rajdeep Mohan; Dewanjee, Ram Krishna; Dugad, Shashikant; Ganguly, Sanmay; Ghosh, Saranya; Guchait, Monoranjan; Gurtu, Atul; Kole, Gouranga; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Mohanty, Gagan Bihari; Parida, Bibhuti; Sudhakar, Katta; Wickramage, Nadeesha; Bakhshiansohi, Hamed; Behnamian, Hadi; Etesami, Seyed Mohsen; Fahim, Ali; Goldouzian, Reza; Jafari, Abideh; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Barbone, Lucia; Calabria, Cesare; Chhibra, Simranjit Singh; Colaleo, Anna; Creanza, Donato; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Selvaggi, Giovanna; Silvestris, Lucia; Singh, Gurpreet; Venditti, Rosamaria; Verwilligen, Piet; Zito, Giuseppe; Abbiendi, Giovanni; Benvenuti, Alberto; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Primavera, Federica; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Travaglini, Riccardo; Albergo, Sebastiano; Cappello, Gigi; Chiorboli, Massimiliano; Costa, Salvatore; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Gallo, Elisabetta; Gonzi, Sandro; Gori, Valentina; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Tropiano, Antonio; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Ferro, Fabrizio; Lo Vetere, Maurizio; Robutti, Enrico; Tosi, Silvano; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Gerosa, Raffaele; Ghezzi, Alessio; Govoni, Pietro; Lucchini, Marco Toliman; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Martelli, Arabella; Marzocchi, Badder; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Redaelli, Nicola; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Di Guida, Salvatore; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lista, Luca; Meola, Sabino; Merola, Mario; Paolucci, Pierluigi; Azzi, Patrizia; Bacchetta, Nicola; Bisello, Dario; Branca, Antonio; Carlin, Roberto; Dall'Osso, Martino; Dorigo, Tommaso; Galanti, Mario; Gasparini, Fabrizio; Giubilato, Piero; Gozzelino, Andrea; Kanishchev, Konstantin; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Montecassiano, Fabio; Passaseo, Marina; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Tosi, Mia; Vanini, Sara; Zotto, Pierluigi; Zucchetta, Alberto; Zumerle, Gianni; Gabusi, Michele; Ratti, Sergio P; Riccardi, Cristina; Salvini, Paola; Vitulo, Paolo; Biasini, Maurizio; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Mantovani, Giancarlo; Menichelli, Mauro; Romeo, Francesco; Saha, Anirban; Santocchia, Attilio; Spiezia, Aniello; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Broccolo, Giuseppe; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Donato, Silvio; Fiori, Francesco; Foà, Lorenzo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Moon, Chang-Seong; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Serban, Alin Titus; Spagnolo, Paolo; Squillacioti, Paola; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Vernieri, Caterina; Barone, Luciano; Cavallari, Francesca; Del Re, Daniele; Diemoz, Marcella; Grassi, Marco; Jorda, Clara; Longo, Egidio; Margaroli, Fabrizio; Meridiani, Paolo; Micheli, Francesco; Nourbakhsh, Shervin; Organtini, Giovanni; Paramatti, Riccardo; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Soffi, Livia; Traczyk, Piotr; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Casasso, Stefano; Costa, Marco; Degano, Alessandro; Demaria, Natale; Finco, Linda; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Musich, Marco; Obertino, Maria Margherita; Ortona, Giacomo; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Potenza, Alberto; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Solano, Ada; Staiano, Amedeo; Tamponi, Umberto; Belforte, Stefano; Candelise, Vieri; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Gobbo, Benigno; La Licata, Chiara; Marone, Matteo; Montanino, Damiana; Schizzi, Andrea; Umer, Tomo; Zanetti, Anna; Chang, Sunghyun; Kropivnitskaya, Anna; Nam, Soon-Kwon; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Kong, Dae Jung; Lee, Sangeun; Oh, Young Do; Park, Hyangkyu; Sakharov, Alexandre; Son, Dong-Chul; Kim, Jae Yool; Song, Sanghyeon; Choi, Suyong; Gyun, Dooyeon; Hong, Byung-Sik; Jo, Mihee; Kim, Hyunchul; Kim, Yongsun; Lee, Byounghoon; Lee, Kyong Sei; Park, Sung Keun; Roh, Youn; Choi, Minkyoo; Kim, Ji Hyun; Park, Inkyu; Park, Sangnam; Ryu, Geonmo; Ryu, Min Sang; Choi, Young-Il; Choi, Young Kyu; Goh, Junghwan; Kwon, Eunhyang; Lee, Jongseok; Seo, Hyunkwan; Yu, Intae; Juodagalvis, Andrius; Komaragiri, Jyothsna Rani; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-de La Cruz, Ivan; Lopez-Fernandez, Ricardo; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Vazquez Valencia, Fabiola; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Casimiro Linares, Edgar; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Reucroft, Steve; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khalid, Shoaib; Khan, Wajid Ali; Khurshid, Taimoor; Shah, Mehar Ali; Shoaib, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Brona, Grzegorz; Bunkowski, Karol; Cwiok, Mikolaj; Dominik, Wojciech; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michał; Wolszczak, Weronika; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Karjavin, Vladimir; Konoplyanikov, Viktor; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Savina, Maria; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Safronov, Grigory; Semenov, Sergey; Spiridonov, Alexander; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Dordevic, Milos; Ekmedzic, Marko; Milosevic, Jovan; Alcaraz Maestre, Juan; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Domínguez Vázquez, Daniel; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Merino, Gonzalo; Navarro De Martino, Eduardo; Pérez Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Brun, Hugues; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Lloret Iglesias, Lara; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Duarte Campderros, Jordi; Fernandez, Marcos; Gomez, Gervasio; Graziano, Alberto; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Benaglia, Andrea; Bendavid, Joshua; Benhabib, Lamia; Benitez, Jose F; Bernet, Colin; Bianchi, Giovanni; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Bondu, Olivier; Botta, Cristina; Breuker, Horst; Camporesi, Tiziano; Cerminara, Gianluca; Christiansen, Tim; Colafranceschi, Stefano; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; David Tinoco Mendes, Andre; De Guio, Federico; De Roeck, Albert; De Visscher, Simon; Dobson, Marc; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Eugster, Jürg; Franzoni, Giovanni; Funk, Wolfgang; Giffels, Manuel; Gigi, Dominique; Gill, Karl; Giordano, Domenico; Girone, Maria; Glege, Frank; Guida, Roberto; Gundacker, Stefan; Guthoff, Moritz; Hammer, Josef; Hansen, Magnus; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kousouris, Konstantinos; Krajczar, Krisztian; Lecoq, Paul; Lourenco, Carlos; Magini, Nicolo; Malgeri, Luca; Mannelli, Marcello; Masetti, Lorenzo; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Musella, Pasquale; Orsini, Luciano; Pape, Luc; Perez, Emmanuelle; Perrozzi, Luca; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Pimiä, Martti; Piparo, Danilo; Plagge, Michael; Racz, Attila; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Sekmen, Sezen; Sharma, Archana; Siegrist, Patrice; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Spiga, Daniele; Steggemann, Jan; Stieger, Benjamin; Stoye, Markus; Treille, Daniel; Tsirou, Andromachi; Veres, Gabor Istvan; Vlimant, Jean-Roch; Wardle, Nicholas; Wöhri, Hermine Katharina; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; König, Stefan; Kotlinski, Danek; Langenegger, Urs; Renker, Dieter; Rohe, Tilman; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Bortignon, Pierluigi; Buchmann, Marco-Andrea; Casal, Bruno; Chanon, Nicolas; Deisher, Amanda; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dünser, Marc; Eller, Philipp; Grab, Christoph; Hits, Dmitry; Lustermann, Werner; Mangano, Boris; Marini, Andrea Carlo; Martinez Ruiz del Arbol, Pablo; Meister, Daniel; Mohr, Niklas; Nägeli, Christoph; Nef, Pascal; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pauss, Felicitas; Peruzzi, Marco; Quittnat, Milena; Rebane, Liis; Ronga, Frederic Jean; Rossini, Marco; Starodumov, Andrei; Takahashi, Maiko; Theofilatos, Konstantinos; Wallny, Rainer; Weber, Hannsjoerg Artur; Amsler, Claude; Canelli, Maria Florencia; Chiochia, Vincenzo; De Cosa, Annapaola; Hinzmann, Andreas; Hreus, Tomas; Ivova Rikova, Mirena; Kilminster, Benjamin; Millan Mejias, Barbara; Ngadiuba, Jennifer; Robmann, Peter; Snoek, Hella; Taroni, Silvia; Verzetti, Mauro; Yang, Yong; Cardaci, Marco; Chen, Kuan-Hsin; Ferro, Cristina; Kuo, Chia-Ming; Lin, Willis; Lu, Yun-Ju; Volpe, Roberta; Yu, Shin-Shan; Chang, Paoti; Chang, You-Hao; Chang, Yu-Wei; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Dietz, Charles; Grundler, Ulysses; Hou, George Wei-Shu; Kao, Kai-Yi; Lei, Yeong-Jyi; Liu, Yueh-Feng; Lu, Rong-Shyang; Majumder, Devdatta; Petrakou, Eleni; Shi, Xin; Tzeng, Yeng-Ming; Wilken, Rachel; Asavapibhop, Burin; Srimanobhas, Norraphat; Suwonjandee, Narumon; Adiguzel, Aytul; Bakirci, Mustafa Numan; Cerci, Salim; Dozen, Candan; Dumanoglu, Isa; Eskut, Eda; Girgis, Semiray; Gokbulut, Gul; Gurpinar, Emine; Hos, Ilknur; Kangal, Evrim Ersin; Kayis Topaksu, Aysel; Onengut, Gulsen; Ozdemir, Kadri; Ozturk, Sertac; Polatoz, Ayse; Sogut, Kenan; Sunar Cerci, Deniz; Tali, Bayram; Topakli, Huseyin; Vergili, Mehmet; Akin, Ilina Vasileva; Bilin, Bugra; Bilmis, Selcuk; Gamsizkan, Halil; Karapinar, Guler; Ocalan, Kadir; Surat, Ugur Emrah; Yalvac, Metin; Zeyrek, Mehmet; Gülmez, Erhan; Isildak, Bora; Kaya, Mithat; Kaya, Ozlem; Bahtiyar, Hüseyin; Barlas, Esra; Cankocak, Kerem; Vardarli, Fuat Ilkehan; Yücel, Mete; Levchuk, Leonid; Sorokin, Pavel; Brooke, James John; Clement, Emyr; Cussans, David; Flacher, Henning; Frazier, Robert; Goldstein, Joel; Grimes, Mark; Heath, Greg P; Heath, Helen F; Jacob, Jeson; Kreczko, Lukasz; Lucas, Chris; Meng, Zhaoxia; Newbold, Dave M; Paramesvaran, Sudarshan; Poll, Anthony; Senkin, Sergey; Smith, Vincent J; Williams, Thomas; Bell, Ken W; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Womersley, William John; Worm, Steven; Baber, Mark; Bainbridge, Robert; Buchmuller, Oliver; Burton, Darren; Colling, David; Cripps, Nicholas; Cutajar, Michael; Dauncey, Paul; Davies, Gavin; Della Negra, Michel; Dunne, Patrick; Ferguson, William; Fulcher, Jonathan; Futyan, David; Gilbert, Andrew; Hall, Geoffrey; Iles, Gregory; Jarvis, Martyn; Karapostoli, Georgia; Kenzie, Matthew; Lane, Rebecca; Lucas, Robyn; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Marrouche, Jad; Mathias, Bryn; Nash, Jordan; Nikitenko, Alexander; Pela, Joao; Pesaresi, Mark; Petridis, Konstantinos; Raymond, David Mark; Rogerson, Samuel; Rose, Andrew; Seez, Christopher; Sharp, Peter; Tapper, Alexander; Vazquez Acosta, Monica; Virdee, Tejinder; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Leggat, Duncan; Leslie, Dawn; Martin, William; Reid, Ivan; Symonds, Philip; Teodorescu, Liliana; Turner, Mark; Dittmann, Jay; Hatakeyama, Kenichi; Kasmi, Azeddine; Liu, Hongxuan; Scarborough, Tara; Charaf, Otman; Cooper, Seth; Henderson, Conor; Rumerio, Paolo; Avetisyan, Aram; Bose, Tulika; Fantasia, Cory; Heister, Arno; Lawson, Philip; Richardson, Clint; Rohlf, James; Sperka, David; St John, Jason; Sulak, Lawrence; Alimena, Juliette; Bhattacharya, Saptaparna; Christopher, Grant; Cutts, David; Demiragli, Zeynep; Ferapontov, Alexey; Garabedian, Alex; Heintz, Ulrich; Jabeen, Shabnam; Kukartsev, Gennadiy; Laird, Edward; Landsberg, Greg; Luk, Michael; Narain, Meenakshi; Segala, Michael; Sinthuprasith, Tutanon; Speer, Thomas; Swanson, Joshua; Breedon, Richard; Breto, Guillermo; Calderon De La Barca Sanchez, Manuel; Chauhan, Sushil; Chertok, Maxwell; Conway, John; Conway, Rylan; Cox, Peter Timothy; Erbacher, Robin; Gardner, Michael; Ko, Winston; Lander, Richard; Miceli, Tia; Mulhearn, Michael; Pellett, Dave; Pilot, Justin; Ricci-Tam, Francesca; Searle, Matthew; Shalhout, Shalhout; Smith, John; Squires, Michael; Stolp, Dustin; Tripathi, Mani; Wilbur, Scott; Yohay, Rachel; Cousins, Robert; Everaerts, Pieter; Farrell, Chris; Hauser, Jay; Ignatenko, Mikhail; Rakness, Gregory; Takasugi, Eric; Valuev, Vyacheslav; Weber, Matthias; Babb, John; Clare, Robert; Ellison, John Anthony; Gary, J William; Hanson, Gail; Heilman, Jesse; Jandir, Pawandeep; Kennedy, Elizabeth; Lacroix, Florent; Liu, Hongliang; Long, Owen Rosser; Luthra, Arun; Malberti, Martina; Nguyen, Harold; Shrinivas, Amithabh; Sturdy, Jared; Sumowidagdo, Suharyo; Wimpenny, Stephen; Andrews, Warren; Branson, James G; Cerati, Giuseppe Benedetto; Cittolin, Sergio; D'Agnolo, Raffaele Tito; Evans, David; Holzner, André; Kelley, Ryan; Lebourgeois, Matthew; Letts, James; Macneill, Ian; Olivito, Dominick; Padhi, Sanjay; Palmer, Christopher; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Sudano, Elizabeth; Tadel, Matevz; Tu, Yanjun; Vartak, Adish; Würthwein, Frank; Yagil, Avraham; Yoo, Jaehyeok; Barge, Derek; Bradmiller-Feld, John; Campagnari, Claudio; Danielson, Thomas; Dishaw, Adam; Flowers, Kristen; Franco Sevilla, Manuel; Geffert, Paul; George, Christopher; Golf, Frank; Incandela, Joe; Justus, Christopher; Mccoll, Nickolas; Richman, Jeffrey; Stuart, David; To, Wing; West, Christopher; Apresyan, Artur; Bornheim, Adolf; Bunn, Julian; Chen, Yi; Di Marco, Emanuele; Duarte, Javier; Mott, Alexander; Newman, Harvey B; Pena, Cristian; Rogan, Christopher; Spiropulu, Maria; Timciuc, Vladlen; Wilkinson, Richard; Xie, Si; Zhu, Ren-Yuan; Azzolini, Virginia; Calamba, Aristotle; Carroll, Ryan; Ferguson, Thomas; Iiyama, Yutaro; Paulini, Manfred; Russ, James; Vogel, Helmut; Vorobiev, Igor; Cumalat, John Perry; Drell, Brian Robert; Ford, William T; Gaz, Alessandro; Luiggi Lopez, Eduardo; Nauenberg, Uriel; Smith, James; Stenson, Kevin; Ulmer, Keith; Wagner, Stephen Robert; Alexander, James; Chatterjee, Avishek; Chu, Jennifer; Dittmer, Susan; Eggert, Nicholas; Hopkins, Walter; Kreis, Benjamin; Mirman, Nathan; Nicolas Kaufman, Gala; Patterson, Juliet Ritchie; Ryd, Anders; Salvati, Emmanuele; Skinnari, Louise; Sun, Werner; Teo, Wee Don; Thom, Julia; Thompson, Joshua; Tucker, Jordan; Weng, Yao; Winstrom, Lucas; Wittich, Peter; Winn, Dave; Abdullin, Salavat; Albrow, Michael; Anderson, Jacob; Apollinari, Giorgio; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Burkett, Kevin; Butler, Joel Nathan; Cheung, Harry; Chlebana, Frank; Cihangir, Selcuk; Elvira, Victor Daniel; Fisk, Ian; Freeman, Jim; Gottschalk, Erik; Gray, Lindsey; Green, Dan; Grünendahl, Stefan; Gutsche, Oliver; Hanlon, Jim; Hare, Daryl; Harris, Robert M; Hirschauer, James; Hooberman, Benjamin; Jindariani, Sergo; Johnson, Marvin; Joshi, Umesh; Kaadze, Ketino; Klima, Boaz; Kwan, Simon; Linacre, Jacob; Lincoln, Don; Lipton, Ron; Liu, Tiehui; Lykken, Joseph; Maeshima, Kaori; Marraffino, John Michael; Martinez Outschoorn, Verena Ingrid; Maruyama, Sho; Mason, David; McBride, Patricia; Mishra, Kalanand; Mrenna, Stephen; Musienko, Yuri; Nahn, Steve; Newman-Holmes, Catherine; O'Dell, Vivian; Prokofyev, Oleg; Sexton-Kennedy, Elizabeth; Sharma, Seema; Soha, Aron; Spalding, William J; Spiegel, Leonard; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vidal, Richard; Whitbeck, Andrew; Whitmore, Juliana; Yang, Fan; Acosta, Darin; Avery, Paul; Bourilkov, Dimitri; Carver, Matthew; Cheng, Tongguang; Curry, David; Das, Souvik; De Gruttola, Michele; Di Giovanni, Gian Piero; Field, Richard D; Fisher, Matthew; Furic, Ivan-Kresimir; Hugon, Justin; Konigsberg, Jacobo; Korytov, Andrey; Kypreos, Theodore; Low, Jia Fu; Matchev, Konstantin; Milenovic, Predrag; Mitselmakher, Guenakh; Muniz, Lana; Rinkevicius, Aurelijus; Shchutska, Lesya; Skhirtladze, Nikoloz; Snowball, Matthew; Yelton, John; Zakaria, Mohammed; Gaultney, Vanessa; Hewamanage, Samantha; Linn, Stephan; Markowitz, Pete; Martinez, German; Rodriguez, Jorge Luis; Adams, Todd; Askew, Andrew; Bochenek, Joseph; Diamond, Brendan; Haas, Jeff; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Prosper, Harrison; Veeraraghavan, Venkatesh; Weinberg, Marc; Baarmand, Marc M; Hohlmann, Marcus; Kalakhety, Himali; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Bazterra, Victor Eduardo; Berry, Douglas; Betts, Russell Richard; Bucinskaite, Inga; Cavanaugh, Richard; Evdokimov, Olga; Gauthier, Lucie; Gerber, Cecilia Elena; Hofman, David Jonathan; Khalatyan, Samvel; Kurt, Pelin; Moon, Dong Ho; O'Brien, Christine; Silkworth, Christopher; Turner, Paul; Varelas, Nikos; Albayrak, Elif Asli; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Duru, Firdevs; Haytmyradov, Maksat; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Rahmat, Rahmat; Sen, Sercan; Tan, Ping; Tiras, Emrah; Wetzel, James; Yetkin, Taylan; Yi, Kai; Barnett, Bruce Arnold; Blumenfeld, Barry; Bolognesi, Sara; Fehling, David; Gritsan, Andrei; Maksimovic, Petar; Martin, Christopher; Swartz, Morris; Baringer, Philip; Bean, Alice; Benelli, Gabriele; Bruner, Christopher; Gray, Julia; Kenny III, Raymond Patrick; Murray, Michael; Noonan, Daniel; Sanders, Stephen; Sekaric, Jadranka; Stringer, Robert; Wang, Quan; Wood, Jeffrey Scott; Barfuss, Anne-Fleur; Chakaberia, Irakli; Ivanov, Andrew; Khalil, Sadia; Makouski, Mikhail; Maravin, Yurii; Saini, Lovedeep Kaur; Shrestha, Shruti; Svintradze, Irakli; Gronberg, Jeffrey; Lange, David; Rebassoo, Finn; Wright, Douglas; Baden, Drew; Calvert, Brian; Eno, Sarah Catherine; Gomez, Jaime; Hadley, Nicholas John; Kellogg, Richard G; Kolberg, Ted; Lu, Ying; Marionneau, Matthieu; Mignerey, Alice; Pedro, Kevin; Skuja, Andris; Tonjes, Marguerite; Tonwar, Suresh C; Apyan, Aram; Barbieri, Richard; Bauer, Gerry; Busza, Wit; Cali, Ivan Amos; Chan, Matthew; Di Matteo, Leonardo; Dutta, Valentina; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Gulhan, Doga; Klute, Markus; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew; Luckey, Paul David; Ma, Teng; Paus, Christoph; Ralph, Duncan; Roland, Christof; Roland, Gunther; Stephans, George; Stöckli, Fabian; Sumorok, Konstanty; Velicanu, Dragos; Veverka, Jan; Wyslouch, Bolek; Yang, Mingming; Zanetti, Marco; Zhukova, Victoria; Dahmes, Bryan; De Benedetti, Abraham; Gude, Alexander; Kao, Shih-Chuan; Klapoetke, Kevin; Kubota, Yuichi; Mans, Jeremy; Pastika, Nathaniel; Rusack, Roger; Singovsky, Alexander; Tambe, Norbert; Turkewitz, Jared; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bloom, Kenneth; Bose, Suvadeep; Claes, Daniel R; Dominguez, Aaron; Gonzalez Suarez, Rebeca; Keller, Jason; Knowlton, Dan; Kravchenko, Ilya; Lazo-Flores, Jose; Malik, Sudhir; Meier, Frank; Snow, Gregory R; Dolen, James; Godshalk, Andrew; Iashvili, Ia; Kharchilava, Avto; Kumar, Ashish; Rappoccio, Salvatore; Alverson, George; Barberis, Emanuela; Baumgartel, Darin; Chasco, Matthew; Haley, Joseph; Massironi, Andrea; Morse, David Michael; Nash, David; Orimoto, Toyoko; Trocino, Daniele; Wood, Darien; Zhang, Jinzhong; Hahn, Kristan Allan; Kubik, Andrew; Mucia, Nicholas; Odell, Nathaniel; Pollack, Brian; Pozdnyakov, Andrey; Schmitt, Michael Henry; Stoynev, Stoyan; Sung, Kevin; Velasco, Mayda; Won, Steven; Brinkerhoff, Andrew; Chan, Kwok Ming; Drozdetskiy, Alexey; Hildreth, Michael; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Luo, Wuming; Lynch, Sean; Marinelli, Nancy; Pearson, Tessa; Planer, Michael; Ruchti, Randy; Valls, Nil; Wayne, Mitchell; Wolf, Matthias; Woodard, Anna; Antonelli, Louis; Brinson, Jessica; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Hill, Christopher; Hughes, Richard; Kotov, Khristian; Ling, Ta-Yung; Puigh, Darren; Rodenburg, Marissa; Smith, Geoffrey; Vuosalo, Carl; Winer, Brian L; Wolfe, Homer; Wulsin, Howard Wells; Berry, Edmund; Driga, Olga; Elmer, Peter; Hebda, Philip; Hunt, Adam; Koay, Sue Ann; Lujan, Paul; Marlow, Daniel; Medvedeva, Tatiana; Mooney, Michael; Olsen, James; Piroué, Pierre; Quan, Xiaohang; Saka, Halil; Stickland, David; Tully, Christopher; Werner, Jeremy Scott; Zenz, Seth Conrad; Zuranski, Andrzej; Brownson, Eric; Mendez, Hector; Ramirez Vargas, Juan Eduardo; Alagoz, Enver; Barnes, Virgil E; Benedetti, Daniele; Bolla, Gino; Bortoletto, Daniela; De Mattia, Marco; Everett, Adam; Hu, Zhen; Jha, Manoj; Jones, Matthew; Jung, Kurt; Kress, Matthew; Leonardo, Nuno; Lopes Pegna, David; Maroussov, Vassili; Merkel, Petra; Miller, David Harry; Neumeister, Norbert; Radburn-Smith, Benjamin Charles; Shipsey, Ian; Silvers, David; Svyatkovskiy, Alexey; Wang, Fuqiang; Xie, Wei; Xu, Lingshan; Yoo, Hwi Dong; Zablocki, Jakub; Zheng, Yu; Parashar, Neeti; Stupak, John; Adair, Antony; Akgun, Bora; Ecklund, Karl Matthew; Geurts, Frank JM; Li, Wei; Michlin, Benjamin; Padley, Brian Paul; Redjimi, Radia; Roberts, Jay; Zabel, James; Betchart, Burton; Bodek, Arie; Covarelli, Roberto; de Barbaro, Pawel; Demina, Regina; Eshaq, Yossof; Ferbel, Thomas; Garcia-Bellido, Aran; Goldenzweig, Pablo; Han, Jiyeon; Harel, Amnon; Khukhunaishvili, Aleko; Miner, Daniel Carl; Petrillo, Gianluca; Vishnevskiy, Dmitry; Ciesielski, Robert; Demortier, Luc; Goulianos, Konstantin; Lungu, Gheorghe; Mesropian, Christina; Arora, Sanjay; Barker, Anthony; Chou, John Paul; Contreras-Campana, Christian; Contreras-Campana, Emmanuel; Duggan, Daniel; Ferencek, Dinko; Gershtein, Yuri; Gray, Richard; Halkiadakis, Eva; Hidas, Dean; Lath, Amitabh; Panwalkar, Shruti; Park, Michael; Patel, Rishi; Rekovic, Vladimir; Salur, Sevil; Schnetzer, Steve; Seitz, Claudia; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Rose, Keith; Spanier, Stefan; York, Andrew; Bouhali, Othmane; Eusebi, Ricardo; Flanagan, Will; Gilmore, Jason; Kamon, Teruki; Khotilovich, Vadim; Krutelyov, Vyacheslav; Montalvo, Roy; Osipenkov, Ilya; Pakhotin, Yuriy; Perloff, Alexx; Roe, Jeffrey; Rose, Anthony; Safonov, Alexei; Sakuma, Tai; Suarez, Indara; Tatarinov, Aysen; Akchurin, Nural; Cowden, Christopher; Damgov, Jordan; Dragoiu, Cosmin; Dudero, Phillip Russell; Faulkner, James; Kovitanggoon, Kittikul; Kunori, Shuichi; Lee, Sung Won; Libeiro, Terence; Volobouev, Igor; Appelt, Eric; Delannoy, Andrés G; Greene, Senta; Gurrola, Alfredo; Johns, Willard; Maguire, Charles; Mao, Yaxian; Melo, Andrew; Sharma, Monika; Sheldon, Paul; Snook, Benjamin; Tuo, Shengquan; Velkovska, Julia; Arenton, Michael Wayne; Boutle, Sarah; Cox, Bradley; Francis, Brian; Goodell, Joseph; Hirosky, Robert; Ledovskoy, Alexander; Li, Hengne; Lin, Chuanzhe; Neu, Christopher; Wood, John; Gollapinni, Sowjanya; Harr, Robert; Karchin, Paul Edmund; Kottachchi Kankanamge Don, Chamath; Lamichhane, Pramod; Belknap, Donald; Carlsmith, Duncan; Cepeda, Maria; Dasu, Sridhara; Duric, Senka; Friis, Evan; Hall-Wilton, Richard; Herndon, Matthew; Hervé, Alain; Klabbers, Pamela; Klukas, Jeffrey; Lanaro, Armando; Lazaridis, Christos; Levine, Aaron; Loveless, Richard; Mohapatra, Ajit; Ojalvo, Isabel; Perry, Thomas; Pierro, Giuseppe Antonio; Polese, Giovanni; Ross, Ian; Sarangi, Tapas; Savin, Alexander; Smith, Wesley H; Woods, Nathaniel

    2014-08-18

    The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7 inverse-femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale.

  12. Search for jet extinction in the inclusive jet-pt spectrum from proton-proton collisions at sqrt(s) = 8 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Khachatryan, Vardan [Yerevan Physcis Institute (Armenia); et al.,

    2014-08-01

    The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale.

  13. Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal- and micro-gravity

    KAUST Repository

    Hu, Longhua

    2016-10-02

    Materials, such as electrical wire, used in spacecraft must pass stringent fire safety standards. Tests for such standards are typically performed under normal gravity conditions and then extended to applications under microgravity conditions. The experiments reported here used polyethylene (PE)-insulated (thickness of 0.15 mm) Nichrome (NiCr)-core (diameter of 0.5 mm) electrical wires. Limiting oxygen concentrations (LOC) at extinction were measured for upward spreading flame at various forced opposed-flow (downward) speeds (0−25 cm/s) at several inclination angles (0−75°) under normal gravity conditions. The differences from those previously obtained under microgravity conditions were quantified and correlated to provide a reference for the development of fire safety test standards for electrical wires to be used in space exploration. It was found that as the opposed-flow speed increased for a specified inclination angle (except the horizontal case), LOC first increased, then decreased and finally increased again. The first local maximum of this LOC variation corresponded to a critical forced flow speed resulted from the change in flame spread pattern from concurrent to counter-current type. This critical forced flow speed correlated well with the buoyancy-induced flow speed component in the wire\\'s direction when the flame base width along the wire was used as a characteristic length scale. LOC was generally higher under the normal gravity than under the microgravity and the difference between the two decreased as the opposed-flow speed increases, following a reasonably linear trend at relatively higher flow speeds (over 10 cm/s). The decrease in the difference in LOC under normal- and microgravity conditions as the opposed-flow speed increases correlated well with the gravity acceleration component in the wire\\'s direction, providing a measure to extend LOC determined by the tests under normal gravity conditions (at various inclination angles and opposed

  14. HIGHLY VARIABLE EXTINCTION AND ACCRETION IN THE JET-DRIVING CLASS I-TYPE YOUNG STAR PTF 10nvg (V2492 Cyg, IRAS 20496+4354)

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, Lynne A.; Carpenter, John M.; Muirhead, Philip S.; Crepp, Justin R. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Miller, Adam A.; Cenko, S. Bradley; Silverman, Jeffrey M.; Bloom, Joshua S.; Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Covey, Kevin R. [Department of Astronomy, Cornell University, 226 Space Sciences Building, Ithaca, NY 14853 (United States); Fischer, William J. [Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States)

    2013-03-15

    We report extensive new photometry and spectroscopy of the highly variable young stellar object PTF 10nvg (also known as IRAS 20496+4354 and V2492 Cyg), including optical and near-infrared time-series data as well as mid-infrared and millimeter data. Following the previously reported 2010 rise to R{sub PTF} {approx}<13.{sup m}5 and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening, followed by several magnitude dimming events including prolonged faint states at R{sub PTF} {approx}> 20{sup m}. The observed high-amplitude variations are largely consistent with extinction changes ({Delta}A{sub V} up to 30 mag) having a {approx}220 day quasi-periodic signal. However, photometry measured when the source was near maximum brightness in mid-2010 as well as in late-2012 does not phase well to this period. Spectral evolution includes not only changes in the spectral slope but also correlated variation in the prominence of TiO/VO/CO bands and atomic line emission, as well as anti-correlated variation in forbidden line emission which, along with H{sub 2}, dominates optical and infrared spectra at faint epochs. Notably, night-to-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra were obtained in a variety of photometric states and reveal time-variable line profiles. Neutral and singly ionized atomic species are likely formed in an accretion flow and/or impact while the origin of zero-velocity atomic Li I {lambda}6707 in emission is unknown. Forbidden lines, including several rare species, exhibit blueshifted emission profiles and likely arise from an outflow/jet. Several of these lines are also seen spatially offset from the continuum source position, presumably in a shocked region of an extended jet. Blueshifted absorption components of the Na I D doublet, K I {lambda}{lambda}7665, 7669 doublet, and the O I 7774 triplet, as well as blueshifted absorption components seen against

  15. Opposing incentives for collaboration

    DEFF Research Database (Denmark)

    Dorch, Bertil F.; Wien, Charlotte; Larsen, Asger Væring

    , and gives a bonus for publications done through inter-institutionary collaboration. Credits given to universities are fractionalized between the participating universities. So far credits are not assigned to the individual authors but only to their institutions. However, it turns out that research...... collaboration is associated with a higher number of citations than single authorship which may present the author with two opposing incentives for research collaboration....

  16. Rethinking Extinction

    Science.gov (United States)

    Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

    2015-01-01

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavioral technique, and consider whether traditional understandings warrant a re-examination. We discuss the neurobiology, cognitive factors, and major computational theories, and revisit the predominant view that extinction results in new learning that interferes with expression of the original memory. Additionally, we reconsider the limitations of extinction as a technique to prevent the relapse of maladaptive behavior, and discuss novel approaches, informed by contemporary theoretical advances, that augment traditional extinction methods to target and potentially alter maladaptive memories. PMID:26447572

  17. Rethinking Extinction

    OpenAIRE

    Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

    2015-01-01

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavior...

  18. Interracial America. Opposing Viewpoints Series.

    Science.gov (United States)

    Szumski, Bonnie, Ed.

    Books in the Opposing Viewpoints Series present debates about current issues that can be used to teach critical reading and thinking skills. The varied opinions in each book examine different aspects of a single issue. The topics covered in this volume explore the racial and ethnic tensions that concern many Americans today. The racial divide…

  19. Religious coalition opposes gene patents.

    Science.gov (United States)

    James, J S

    1995-05-19

    The biotechnology industry is concerned about a coalition of mainstream religious leaders, working with Jeremy Rifkin of the Foundation of Economic Trends, who oppose the patenting of human and animal life forms, body parts, and genes. The coalition called a press conference on May 18 to ask the government to prohibit the current patenting practices for genetic engineering. The biotechnology industry argues that patents indicate that a company's research tool has significant value, and encourages capitalists to invest their dollars in the development of new treatments for diseases. They also argue that the 29 biotech drugs that are on the market have been developed as a result of patents on genes. Although most business leaders are united in opposing restrictions, many scientists are divided, citing both religious and scientific reasons.

  20. Interstellar Extinction

    OpenAIRE

    Gontcharov, George

    2017-01-01

    This review describes our current understanding of interstellar extinction. This differ substantially from the ideas of the 20th century. With infrared surveys of hundreds of millions of stars over the entire sky, such as 2MASS, SPITZER-IRAC, and WISE, we have looked at the densest and most rarefied regions of the interstellar medium at distances of a few kpc from the sun. Observations at infrared and microwave wavelengths, where the bulk of the interstellar dust absorbs and radiates, have br...

  1. Opposed slant tube diabatic sorber

    Science.gov (United States)

    Erickson, Donald C.

    2004-01-20

    A sorber comprised of at least three concentric coils of tubing contained in a shell with a flow path for liquid sorbent in one direction, a flow path for heat transfer fluid which is in counter-current heat exchange relationship with sorbent flow, a sorbate vapor port in communication with at least one of sorbent inlet or exit ports, wherein each coil is coiled in opposite direction to those coils adjoining it, whereby the opposed slant tube configuration is achieved, with structure for flow modification in the core space inside the innermost coil.

  2. Impossible Extinction

    Science.gov (United States)

    Cockell, Charles S.

    2003-03-01

    Every 225 million years the Earth, and all the life on it, completes one revolution around the Milky Way Galaxy. During this remarkable journey, life is influenced by calamitous changes. Comets and asteroids strike the surface of the Earth, stars explode, enormous volcanoes erupt, and, more recently, humans litter the planet with waste. Many animals and plants become extinct during the voyage, but humble microbes, simple creatures made of a single cell, survive this journey. This book takes a tour of the microbial world, from the coldest and deepest places on Earth to the hottest and highest, and witnesses some of the most catastrophic events that life can face. Impossible Extinction tells this remarkable story to the general reader by explaining how microbes have survived on Earth for over three billion years. Charles Cockell received his doctorate from the University of Oxford, and is currently a microbiologist with rhe Search for Extraterrestrial Intelligence Institute (SETI), based at the British Antarctic Survey in Cambridge, UK. His research focusses on astrobiology, life in the extremes and the human exploration of Mars. Cockell has been on expeditions to the Arctic, Antarctic, Mongolia, and in 1993 he piloted a modified insect-collecting ultra-light aircraft over the Indonesian rainforests. He is Chair of the Twenty-one Eleven Foundation for Exploration, a charity that supports expeditions that forge links between space exploration and environmentalism.

  3. Effects of H2O, CO2, and N2 Air Contaminants on Critical Airside Strain Rates for Extinction of Hydrogen-Air Counterflow Diffusion Flames

    Science.gov (United States)

    Pellett, G. L.; Wilson, L. G.; Northam, G. B.; Guerra, Rosemary

    1989-01-01

    Coaxial tubular opposed jet burners (OJB) were used to form dish shaped counterflow diffusion flames (CFDF), centered by opposing laminar jets of H2, N2 and both clean and contaminated air (O2/N2 mixtures) in an argon bath at 1 atm. Jet velocities for flame extinction and restoration limits are shown versus wide ranges of contaminant and O2 concentrations in the air jet, and also input H2 concentration. Blowoff, a sudden breaking of CFDF to a stable ring shape, occurs in highly stretched stagnation flows and is generally believed to measure kinetically limited flame reactivity. Restore, a sudden restoration of central flame, is a relatively new phenomenon which exhibits a H2 dependent hysteresis from Blowoff. For 25 percent O2 air mixtures, mole for mole replacement of 25 percent N2 contaminant by steam increased U(air) or flame strength at Blowoff by about 5 percent. This result is consistent with laminar burning velocity results from analogous substitution of steam for N2 in a premixed stoichiometric H2-O2-N2 (or steam) flame, shown by Koroll and Mulpuru to promote a 10 percent increase in experimental and calculated laminar burning velocity, due to enhanced third body efficiency of water in: H + O2 + M yields HO2 + M. When the OJB results were compared with Liu and MacFarlane's experimental laminar burning velocity of premixed stoichiometric H2 + air + steam, a crossover occurred, i.e., steam enhanced OJB flame strength at extinction relative to laminar burning velocity.

  4. Seasonal atmospheric extinction

    International Nuclear Information System (INIS)

    Mikhail, J.S.

    1979-01-01

    Mean monochromatic extinction coefficients at various wavelengths at the Kottamia Observatory site have shown the existence of a seasonal variation of atmospheric extinction. The extinction of aerosol compontnts with wavelengths at winter represent exceedingly good conditions. Spring gives the highest extinction due to aerosol. (orig.)

  5. Modeling galactic extinction

    OpenAIRE

    Cecchi-Pestellini, C.; Mulas, G.; Casu, S.; Iatì, M. A.; Saija, R.; Cacciola, A.; Borghese, F.; Denti, P.

    2011-01-01

    We present a model for interstellar extinction dust, in which we assume a bimodal distribution of extinction carriers, a dispersion of core-mantle grains, supplemented by a collection of PAHs in free molecular form. We use state-of-the-art methods to calculate the extinction due to macroscopic dust particles, and the absorption cross-sections of PAHs in four different charge states. While successfull for most of observed Galactic extinction curves, in few cases the model cannot provide reliab...

  6. Modern examples of extinctions

    DEFF Research Database (Denmark)

    Lövei, Gabor L

    2013-01-01

    No species lives forever, and extinction is the ultimate fate of all living species. The fossil record indicates that a recent extinction wave affecting terrestrial vertebrates was parallel with the arrival of modern humans to areas formerly uninhabited by them. These modern instances of extinction...

  7. Extinction of laminar partially premixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Room 2039, MC-251, Chicago, IL 60607-7022 (United States)

    2009-12-15

    Flame extinction represents one of the classical phenomena in combustion science. It is important to a variety of combustion systems in transportation and power generation applications. Flame extinguishment studies are also motivated from the consideration of fire safety and suppression. Such studies have generally considered non-premixed and premixed flames, although fires can often originate in a partially premixed mode, i.e., fuel and oxidizer are partially premixed as they are transported to the reaction zone. Several recent investigations have considered this scenario and focused on the extinction of partially premixed flames (PPFs). Such flames have been described as hybrid flames possessing characteristics of both premixed and non-premixed flames. This paper provides a review of studies dealing with the extinction of PPFs, which represent a broad family of flames, including double, triple (tribrachial), and edge flames. Theoretical, numerical and experimental studies dealing with the extinction of such flames in coflow and counterflow configurations are discussed. Since these flames contain both premixed and non-premixed burning zones, a brief review of the dilution-induced extinction of premixed and non-premixed flames is also provided. For the coflow configuration, processes associated with flame liftoff and blowout are described. Since lifted non-premixed jet flames often contain a partially premixed or an edge-flame structure prior to blowout, the review also considers such flames. While the perspective of this review is broad focusing on the fundamental aspects of flame extinction and blowout, results mostly consider flame extinction caused by the addition of a flame suppressant, with relevance to fire suppression on earth and in space environment. With respect to the latter, the effect of gravity on the extinction of PPFs is discussed. Future research needs are identified. (author)

  8. Nitric Oxide and Oxygen Air-Contamination Effects on Extinction Limits of Non-Premixed Hydrocarbon-Air Flames for a HIFiRE Scramjet

    Science.gov (United States)

    Pellett, Gerald L.; Dawson, Lucy C.; Vaden, Sarah N.; Wilson, Lloyd G.

    2009-01-01

    Unique nitric oxide (NO) and oxygen air-contamination effects on the extinction Flame Strength (FS) of non-premixed hydrocarbon (HC) vs. air flames are characterized for 7 gaseous HCs, using a new idealized 9.3 mm straight-tube Opposed Jet Burner (OJB) at 1 atm. FS represents a laminar strain-induced extinction limit based on cross-section-average air jet velocity, Uair, that sustains combustion of a counter jet of gaseous fuel just before extinction. Besides ethane, propane, butane, and propylene, the HCs include ethylene, methane, and a 64 mole-% ethylene / 36 % methane mixture, the writer s previously recommended gaseous surrogate fuel for HIFiRE scramjet tests. The HC vs. clean air part of the work is an extension of a May 2008 JANNAF paper that characterized surrogates for the HIFiRE project that should mimic the flameholding of reformed (thermally- or catalytically-cracked) endothermic JP-like fuels. The new FS data for 7 HCs vs. clean air are thus consolidated with the previously validated data, normalized to absolute (local) axial-input strain rates, and co-plotted on a dual kinetically dominated reactivity scale. Excellent agreement with the prior data is obtained for all 7 fuels. Detailed comparisons are also made with recently published (Univ. Va) numerical results for ethylene extinction. A 2009-revised ethylene kinetic model (Univ. Southern Cal) led to predicted limits within approx. 5 % (compared to 45 %, earlier) of this writer s 2008 (and present) ethylene FSs, and also with recent independent data (Univ. Va) obtained on a new OJB system. These +/- 5 % agreements, and a hoped-for "near-identically-performing" reduced kinetics model, would greatly enhance the capability for accurate numerical simulations of surrogate HC flameholding in scramjets. The measured air-contamination effects on normalized FS extinction limits are projected to assess ongoing Arc-Heater-induced "facility test effects" of NO production (e.g., 3 mole-%) and resultant oxygen

  9. Jet observables without jet algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, Daniele; Chan, Tucker; Thaler, Jesse [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2014-04-02

    We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables — jet multiplicity, summed scalar transverse momentum, and missing transverse momentum — have event shape counterparts that are closely correlated with their jet-based cousins. Due to their “local” computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

  10. Bimodal extinction without cross-modal extinction.

    OpenAIRE

    Inhoff, A W; Rafal, R D; Posner, M J

    1992-01-01

    Three patients with unilateral neurological injury were clinically examined. All showed consistent unilateral extinction in the tactile and visual modalities on simultaneous intramodal stimulation. There was virtually no evidence for cross-modal extinction, however, so that contralateral stimulation of one modality would have extinguished perception of ipsilateral stimuli in the other modality. It is concluded that the attentional system controlling the encoding of tactile and visual stimuli ...

  11. Wind wave source functions in opposing seas

    KAUST Repository

    Langodan, Sabique

    2015-08-26

    The Red Sea is a challenge for wave modeling because of its unique two opposed wave systems, forced by opposite winds and converging at its center. We investigate the different physical aspects of wave evolution and propagation in the convergence zone. The two opposing wave systems have similar amplitude and frequency, each driven by the action of its own wind. Wave patterns at the centre of the Red Sea, as derived from extensive tests and intercomparison between model and measured data, suggest that the currently available wave model source functions may not properly represent the evolution of the local fields that appear to be characterized by a less effective wind input and an enhanced white-capping. We propose and test a possible simple solution to improve the wave-model simulation under opposing winds and waves condition. This article is protected by copyright. All rights reserved.

  12. Extinction with multiple excitors

    OpenAIRE

    McConnell, Bridget L.; Miguez, Gonzalo; Miller, Ralph R.

    2013-01-01

    Four conditioned suppression experiments with rats, using an ABC renewal design, investigated the effects of compounding the target conditioned excitor with additional, nontarget conditioned excitors during extinction. Experiment 1 showed stronger extinction, as evidenced by less renewal, when the target excitor was extinguished in compound with a second excitor, relative to when it was extinguished with associatively neutral stimuli. Critically, this deepened extinction effect was attenuated...

  13. End Ordovician extinctions

    DEFF Research Database (Denmark)

    Harper, David A. T.; Hammarlund, Emma; Rasmussen, Christian M. Ø.

    2014-01-01

    -global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were...

  14. Extinction of Chained Instrumental Behaviors: Effects of Procurement Extinction on Consumption Responding

    Science.gov (United States)

    Thrailkill, Eric A.; Bouton, Mark E.

    2015-01-01

    Instrumental behavior often consists of sequences or chains of responses that minimally include procurement behaviors that enable subsequent consumption behaviors. In such chains, behavioral units are linked by access to one another and eventually to a primary reinforcer, such as food or a drug. The present experiments examined the effects of extinguishing procurement responding on consumption responding after training of a discriminated heterogeneous instrumental chain. Rats learned to make a procurement response (e.g., pressing a lever) in the presence of a distinctive discriminative stimulus; making that response led to the presentation of a second discriminative stimulus that set the occasion for a consumption response (e.g., pulling a chain), which then produced a food-pellet reinforcer. Experiment 1 showed that extinction of either the full procurement-consumption chain or procurement alone weakened the consumption response tested in isolation. Experiment 2 replicated the procurement extinction effect and further demonstrated that the opportunity to make the procurement response, as opposed to simple exposure to the procurement stimulus alone, was required. In Experiment 3, rats learned 2 distinct discriminated heterogeneous chains; extinction of 1 procurement response specifically weakened the consumption response that had been associated with it. The results suggest that learning to inhibit the procurement response may produce extinction of consumption responding through mediated extinction. The experiments suggest the importance of an associative analysis of instrumental behavior chains. PMID:25915751

  15. Extinction of NGC 7027

    International Nuclear Information System (INIS)

    Seaton, M.J.

    1979-01-01

    Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from lambda = 2.17 μm to lambda = 1640 A: comparison with the calculated emission intensities gives the extinction. Determinations of the standard interstellar extinction function are critically discussed. The extinction deduced for the total radiation from NGC 7027 has a dependence on wavelength for 6563 A >= lambda >= 1640 A which is in excellent agreement with the adopted standard results, but there are some anomalies for longer wavelengths and for the ratio of total to selective extinction. These can be explained using a model which allows for a local contribution to the extinction which is variable over the surface of the nebula. (author)

  16. Interstellar extinction correlations

    International Nuclear Information System (INIS)

    Jones, A.P.; Williams, D.A.; Duley, W.W.

    1987-01-01

    A recently proposed model for interstellar grains in which the extinction arises from small silicate cores with mantles of hydrogenated amorphous carbon (HAC or α-C:H), and large, but thinly coated, silicate grains can successfully explain many of the observed properties of interstellar dust. The small silicate cores give rise to the 2200 A extinction feature. The extinction in the visual is produced by the large silicates and the HAC mantles on the small cores, whilst the far UV extinction arises in the HAC mantles with a small contribution form the silicate grains. The grain model requires that the silicate material is the more resilient component and that variations in the observed extinction from region to region are due to the nature and depletion of the carbon in the HAC mantles. (author)

  17. Jet fragmentation

    International Nuclear Information System (INIS)

    Saxon, D.H.

    1985-10-01

    The paper reviews studies on jet fragmentation. The subject is discussed under the topic headings: fragmentation models, charged particle multiplicity, bose-einstein correlations, identified hadrons in jets, heavy quark fragmentation, baryon production, gluon and quark jets compared, the string effect, and two successful models. (U.K.)

  18. Extinction and the fossil record

    Science.gov (United States)

    Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

    1994-01-01

    The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

  19. Consecutive opposed interactions of light waves

    International Nuclear Information System (INIS)

    Volkov, V V; Chirkin, Anatolii S

    1999-01-01

    The conditions were determined for the occurrence of the opposed interaction of waves having multiple frequencies in two consecutive three-frequency processes in periodically inhomogeneous nonlinear optical crystals. The necessary nonlinear susceptibility modulation period was calculated for an MgO:LiNbO 3 crystal. The characteristic features of the energy exchange between counterpropagating waves with parametric amplification in a low-frequency pump field were investigated. (nonlinear optical phenomena)

  20. Is IR going extinct?

    Science.gov (United States)

    Mitchell, Audra

    2016-01-01

    A global extinction crisis may threaten the survival of most existing life forms. Influential discourses of ‘existential risk’ suggest that human extinction is a real possibility, while several decades of evidence from conservation biology suggests that the Earth may be entering a ‘sixth mass extinction event’. These conditions threaten the possibilities of survival and security that are central to most branches of International Relations. However, this discipline lacks a framework for addressing (mass) extinction. From notions of ‘nuclear winter’ and ‘omnicide’ to contemporary discourses on catastrophe, International Relations thinking has treated extinction as a superlative of death. This is a profound category mistake: extinction needs to be understood not in the ontic terms of life and death, but rather in the ontological context of be(com)ing and negation. Drawing on the work of theorists of the ‘inhuman’ such as Quentin Meillassoux, Claire Colebrook, Ray Brassier, Jean-Francois Lyotard and Nigel Clark, this article provides a pathway for thinking beyond existing horizons of survival and imagines a profound transformation of International Relations. Specifically, it outlines a mode of cosmopolitics that responds to the element of the inhuman and the forces of extinction. Rather than capitulating to narratives of tragedy, this cosmopolitics would make it possible to think beyond the restrictions of existing norms of ‘humanity’ to embrace an ethics of gratitude and to welcome the possibility of new worlds, even in the face of finitude.

  1. The dilution effect on the extinction of wall diffusion flame

    Directory of Open Access Journals (Sweden)

    Ghiti Nadjib

    2014-12-01

    Full Text Available The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.

  2. Temporal Dynamics of Recovery from Extinction Shortly after Extinction Acquisition

    Science.gov (United States)

    Archbold, Georgina E.; Dobbek, Nick; Nader, Karim

    2013-01-01

    Evidence suggests that extinction is new learning. Memory acquisition involves both short-term memory (STM) and long-term memory (LTM) components; however, few studies have examined early phases of extinction retention. Retention of auditory fear extinction was examined at various time points. Shortly (1-4 h) after extinction acquisition…

  3. The costly benefits of opposing agricultural biotechnology.

    Science.gov (United States)

    Apel, Andrew

    2010-11-30

    Rigorous application of a simple definition of what constitutes opposition to agricultural biotechnology readily encompasses a wide array of key players in national and international systems of food production, distribution and governance. Even though the sum of political and financial benefits of opposing agricultural biotechnology appears vastly to outweigh the benefits which accrue to providers of agricultural biotechnology, technology providers actually benefit from this opposition. If these barriers to biotechnology were removed, subsistence farmers still would not represent a lucrative market for improved seed. The sum of all interests involved ensures that subsistence farmers are systematically denied access to agricultural biotechnology. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Opposite effects of fear conditioning and extinction on dendritic spine remodelling.

    Science.gov (United States)

    Lai, Cora Sau Wan; Franke, Thomas F; Gan, Wen-Biao

    2012-02-19

    It is generally believed that fear extinction is a form of new learning that inhibits rather than erases previously acquired fear memories. Although this view has gained much support from behavioural and electrophysiological studies, the hypothesis that extinction causes the partial erasure of fear memories remains viable. Using transcranial two-photon microscopy, we investigated how neural circuits are modified by fear learning and extinction by examining the formation and elimination of postsynaptic dendritic spines of layer-V pyramidal neurons in the mouse frontal association cortex. Here we show that fear conditioning by pairing an auditory cue with a footshock increases the rate of spine elimination. By contrast, fear extinction by repeated presentation of the same auditory cue without a footshock increases the rate of spine formation. The degrees of spine remodelling induced by fear conditioning and extinction strongly correlate with the expression and extinction of conditioned fear responses, respectively. Notably, spine elimination and formation induced by fear conditioning and extinction occur on the same dendritic branches in a cue- and location-specific manner: cue-specific extinction causes formation of dendritic spines within a distance of two micrometres from spines that were eliminated after fear conditioning. Furthermore, reconditioning preferentially induces elimination of dendritic spines that were formed after extinction. Thus, within vastly complex neuronal networks, fear conditioning, extinction and reconditioning lead to opposing changes at the level of individual synapses. These findings also suggest that fear memory traces are partially erased after extinction.

  5. Stress and Fear Extinction

    Science.gov (United States)

    Maren, Stephen; Holmes, Andrew

    2016-01-01

    Stress has a critical role in the development and expression of many psychiatric disorders, and is a defining feature of posttraumatic stress disorder (PTSD). Stress also limits the efficacy of behavioral therapies aimed at limiting pathological fear, such as exposure therapy. Here we examine emerging evidence that stress impairs recovery from trauma by impairing fear extinction, a form of learning thought to underlie the suppression of trauma-related fear memories. We describe the major structural and functional abnormalities in brain regions that are particularly vulnerable to stress, including the amygdala, prefrontal cortex, and hippocampus, which may underlie stress-induced impairments in extinction. We also discuss some of the stress-induced neurochemical and molecular alterations in these brain regions that are associated with extinction deficits, and the potential for targeting these changes to prevent or reverse impaired extinction. A better understanding of the neurobiological basis of stress effects on extinction promises to yield novel approaches to improving therapeutic outcomes for PTSD and other anxiety and trauma-related disorders. PMID:26105142

  6. Extinction and renewal of cue-elicited reward-seeking.

    Science.gov (United States)

    Bezzina, Louise; Lee, Jessica C; Lovibond, Peter F; Colagiuri, Ben

    2016-12-01

    Reward cues can contribute to overconsumption of food and drugs and can relapse. The failure of exposure therapies to reduce overconsumption and relapse is generally attributed to the context-specificity of extinction. However, no previous study has examined whether cue-elicited reward-seeking (as opposed to cue-reactivity) is sensitive to context renewal. We tested this possibility in 160 healthy volunteers using a Pavlovian-instrumental transfer (PIT) design involving voluntary responding for a high value natural reward (chocolate). One reward cue underwent Pavlovian extinction in the same (Group AAA) or different context (Group ABA) to all other phases. This cue was compared with a second non-extinguished reward cue and an unpaired control cue. There was a significant overall PIT effect with both reward cues eliciting reward-seeking on test relative to the unpaired cue. Pavlovian extinction substantially reduced this effect, with the extinguished reward cue eliciting less reward-seeking than the non-extinguished reward cue. Most interestingly, extinction of cue-elicited reward-seeking was sensitive to renewal, with extinction less effective for reducing PIT when conducted in a different context. These findings have important implications for extinction-based interventions for reducing maladaptive reward-seeking in practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Biological Extinction in Earth History

    Science.gov (United States)

    Raup, David M.

    1986-03-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  8. Biological extinction in earth history

    Science.gov (United States)

    Raup, D. M.

    1986-01-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  9. Interstellar dust and extinction

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1990-01-01

    It is noted that the term interstellar dust refers to materials with rather different properties, and that the mean extinction law of Seaton (1979) or Savage and Mathis (1979) should be replaced by the expression given by Cardelli et al. (1989), using the appropriate value of total-to-selective extinction. The older laws were appropriate for the diffuse ISM but dust in clouds differs dramatically in its extinction law. Dust is heavily processed while in the ISM by being included within clouds and cycled back into the diffuse ISM many times during its lifetime. Hence, grains probably reflect only a trace of their origin, although meteoritic inclusions with isotopic anomalies demonstrate that some tiny particles survive intact from a supernova origin to the present. 186 refs

  10. The role of the dorsal striatum in extinction: A memory systems perspective.

    Science.gov (United States)

    Goodman, Jarid; Packard, Mark G

    2018-04-01

    The present review describes a role for the dorsal striatum in extinction. Evidence from brain lesion and pharmacological studies indicate that the dorsolateral region of the striatum (DLS) mediates extinction in various maze learning and instrumental learning tasks. Within the context of a multiple memory systems view, the role of the DLS in extinction appears to be selective. Specifically, the DLS mediates extinction of habit memory and is not required for extinction of cognitive memory. Thus, extinction mechanisms mediated by the DLS may involve response-produced inhibition (e.g. inhibition of existing stimulus-response associations or formation of new inhibitory stimulus-response associations), as opposed to cognitive mechanisms (e.g. changes in expectation). Evidence also suggests that NMDA-dependent forms of synaptic plasticity may be part of the mechanism through which the DLS mediates extinction of habit memory. In addition, in some learning situations, DLS inactivation enhances extinction, suggesting a competitive interaction between multiple memory systems during extinction training. Consistent with a multiple memory systems perspective, it is suggested that the DLS represents one of several distinct neural systems that specialize in extinction of different kinds of memory. The relevance of these findings to the development of behavioral and pharmacological therapies that target the maladaptive habit-like symptoms in human psychopathology is also briefly considered. Published by Elsevier Inc.

  11. Extinction of sodium fires

    International Nuclear Information System (INIS)

    Malet, J.C.; Spagna, F.

    1989-01-01

    This paper presents how, starting from a knowledge of sodium ignition and burning, principles for extinction (smothering catch trays, leak recuperation systems, powders) can be developed. These techniques applied in Superphenix 1 and PEC reactors have been tested in the ESMERALDA experimental program which is a joint French/Italian project. (author)

  12. Boosted jets

    International Nuclear Information System (INIS)

    Juknevich, J.

    2014-01-01

    We present a study of the substructure of jets high transverse momentum at hadron colliders. A template method is introduced to distinguish heavy jets by comparing their energy distributions to the distributions of a set of templates which describe the kinematical information from signal or background. As an application, a search for a boosted Higgs boson decaying into bottom quarks in association with a leptonically decaying W boson is presented as well. (author)

  13. Emerging Jets

    CERN Document Server

    Schwaller, Pedro; Weiler, Andreas

    2015-01-01

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilit...

  14. Emerging jets

    Energy Technology Data Exchange (ETDEWEB)

    Schwaller, Pedro; Stolarski, Daniel [European Organization for Nuclear Research (CERN), Geneva (Switzerland). TH-PH Div.; Weiler, Andreas [European Organization for Nuclear Research (CERN), Geneva (Switzerland). TH-PH Div.; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2015-02-15

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  15. Emerging jets

    International Nuclear Information System (INIS)

    Schwaller, Pedro; Stolarski, Daniel

    2015-02-01

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  16. Metapopulation extinction risk: dispersal's duplicity.

    Science.gov (United States)

    Higgins, Kevin

    2009-09-01

    Metapopulation extinction risk is the probability that all local populations are simultaneously extinct during a fixed time frame. Dispersal may reduce a metapopulation's extinction risk by raising its average per-capita growth rate. By contrast, dispersal may raise a metapopulation's extinction risk by reducing its average population density. Which effect prevails is controlled by habitat fragmentation. Dispersal in mildly fragmented habitat reduces a metapopulation's extinction risk by raising its average per-capita growth rate without causing any appreciable drop in its average population density. By contrast, dispersal in severely fragmented habitat raises a metapopulation's extinction risk because the rise in its average per-capita growth rate is more than offset by the decline in its average population density. The metapopulation model used here shows several other interesting phenomena. Dispersal in sufficiently fragmented habitat reduces a metapopulation's extinction risk to that of a constant environment. Dispersal between habitat fragments reduces a metapopulation's extinction risk insofar as local environments are asynchronous. Grouped dispersal raises the effective habitat fragmentation level. Dispersal search barriers raise metapopulation extinction risk. Nonuniform dispersal may reduce the effective fraction of suitable habitat fragments below the extinction threshold. Nonuniform dispersal may make demographic stochasticity a more potent metapopulation extinction force than environmental stochasticity.

  17. THE SECONDARY EXTINCTION CORRECTION

    Energy Technology Data Exchange (ETDEWEB)

    Zachariasen, W. H.

    1963-03-15

    It is shown that Darwin's formula for the secondary extinction correction, which has been universally accepted and extensively used, contains an appreciable error in the x-ray diffraction case. The correct formula is derived. As a first order correction for secondary extinction, Darwin showed that one should use an effective absorption coefficient mu + gQ where an unpolarized incident beam is presumed. The new derivation shows that the effective absorption coefficient is mu + 2gQ(1 + cos/sup 4/2 theta )/(1 plus or minus cos/sup 2/2 theta )/s up 2/, which gives mu + gQ at theta =0 deg and theta = 90 deg , but mu + 2gQ at theta = 45 deg . Darwin's theory remains valid when applied to neutron diffraction. (auth)

  18. Galactic dust and extinction

    International Nuclear Information System (INIS)

    Lyngaa, G.

    1979-01-01

    The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

  19. NASA Jet Noise Research

    Science.gov (United States)

    Henderson, Brenda

    2016-01-01

    The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.

  20. Modelling interstellar extinction: Pt. 1

    International Nuclear Information System (INIS)

    Jones, A.P.

    1988-01-01

    Several methods of calculating the extinction of porous silicate grains are discussed, these include effective medium theories and hollow spherical shells. Porous silicate grains are shown to produce enhanced infrared, ultraviolet and far-ultraviolet extinction and this effect can be used to reduce the abundance of carbon required to match the average interstellar extinction, however, matching the visual extinction is rather more problematical. We have shown that the enhanced extinction at long and short wavelengths have different origins, and have explained why the visual extinction is little affected by porosity. The implications of porous grains in the interstellar medium are discussed with particular reference to surface chemistry, the polarization of starlight, and their dynamical evolution. (author)

  1. Extinction Events Can Accelerate Evolution

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate...... evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending...... computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific...

  2. Rescuing Ecosystems from Extinction Cascades

    Science.gov (United States)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  3. Acoustic integrated extinction

    OpenAIRE

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we der...

  4. Mass extinctions of Earth

    International Nuclear Information System (INIS)

    Fernandez, B.; Fernandez, P.; Pereira, B.

    2015-01-01

    Throughout the history of our planet, there have been global phenomena which have led to the disappearance of a large number of species: It is what is known as mass or massive extinctions. This article will make a tour of these large events, from the most remote antiquity to the present day. Today we find ourselves immersed in a process unprecedented since we are eyewitnesses and, more important still, an active part in the decision-making process to try to mitigate their effects. (Author)

  5. Mass extinctions and supernova explosions

    OpenAIRE

    Korschinek, Gunther

    2016-01-01

    A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation, o...

  6. Probing jets from young embedded sources

    Science.gov (United States)

    Nisini, Brunella

    2017-08-01

    Jets are intimately related to the process of star formation and disc accretion. Our present knowledge of this key ingredient in protostars mostly relies on observations of optical jets from T Tauri stars, where the original circumstellar envelope has been already cleared out. However, to understand how jets are originally formed and how their properties evolve with time, detailed observations of young accreting protostars, i.e. the class 0/I sources, are mandatory. The study of class0/I jets will be revolutionised by JWST, able to penetrate protostars dusty envelopes with unprecedented sensitivity and resolution. However, complementary information on parameters inferred from lines in different excitation regimes, for at least a representative sample of a few bright sources, is essential for a correct interpretation of the JWST results. Here we propose to observe four prototype bright jets from class0/I sources with the WFC3 in narrow band filters in order to acquire high angular resolution images in the [OI]6300A, [FeII]1.25 and [FeII]1.64um lines. These images will be used to: 1) provide accurate extinction maps of the jets that will be an important archival reference for any future observation on these jets. 2) measure key parameters as the mass flux, the iron abundance and the jet collimation on the hot gas component of the jets. These information will provide an invaluable reference frame for a comparison with similar parameters measured by JWST in a different gas regime. In addition, these observations will allow us to confront the properties of class 0/I jets with those of the more evolved T Tauri stars.

  7. Extinction of H II regions

    International Nuclear Information System (INIS)

    Israel, F.P.; Kennicutt, R.C.

    1980-01-01

    Visual extinction of H II regions in nine nearby galaxies as derived from the ratio of the radio continuum emission to H-alpha emission is systematically larger than visual extinction deduced from the Balmer lines alone, if one assumes a value Av/E(B-V) 3. An optically-limited sample of about 30 extragalactic H II regions has a mean extinction of 1.7 m in the visual while about 1.2 m is not seen in the reddening of the Balmer lines. Both reddening and extinction decreases with increasing galactic radius, at least for M33 and M101

  8. A reconciliation of extinction theories

    International Nuclear Information System (INIS)

    Sabine, T.M.

    1988-01-01

    The differences between previous theoretical treatments of extinction based on the Darwin intensity equations arise because of the different functional form chosen for the coupling constant σ. When the same function is used these theories make closely similar predictions. It is shown that a limiting condition on integrated intensity as the crystal size increases puts restrictions on the functions which may be used. A Lorentzian or Fresnellian function can be used for primary extinction while secondary extinction requires a Gaussian, rectangular or triangular function. An analytical expression is given for the variation in the value of the extinction factor with scattering angle. (orig.)

  9. Overeruption of teeth opposing removable partial dentures: a preliminary study.

    Science.gov (United States)

    Matsuda, Ken-Ichi; Miyashita, Yuji; Ikebe, Kazunori; Enoki, Kaori; Kurushima, Yuko; Mihara, Yusuke; Maeda, Yoshinobu

    2014-01-01

    One of the purposes of prosthodontic treatment is to prevent overeruption of opposing teeth, but there is currently minimal literature describing the efficacy of removable partial dentures (RPDs) in performing this function. This study investigated overeruption following RPD treatment. The study participants were 33 patients treated with RPDs, and overeruption was evaluated by comparing the surface computeraided design data of dental casts made at two different time points-before and after RPD treatment. Overeruption was observed in 38.1% of teeth opposed by the RPD, which was much less than the proportion of teeth that overerupted when not opposed by the RPD.

  10. Global extinction in spiral galaxies

    NARCIS (Netherlands)

    Tully, RB; Pierce, MJ; Saunders, W; Verheijen, MAW; Witchalls, PL

    Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces Clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in the B, R, I, and K' bands. Extinction causes systematic scatter in

  11. Evolution: Postponing Extinction by Polyandry

    OpenAIRE

    Wade, Michael J.

    2010-01-01

    Sex-ratio meiotic drive occurs when males produce a predominance of X-chromosome bearing sperm and an inordinate number of daughters. A driving X causes highly female-biased sex ratios and the risk of extinction. Polyandry can rescue a population from extinction.

  12. Optimising Extinction of Conditioned Disgust

    NARCIS (Netherlands)

    Bosman, Renske C.; Borg, Charmaine; de Jong, Peter J.

    2016-01-01

    Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS)-only extinction procedures. The relatively strong resistance to extinction might

  13. Behavioral tagging of extinction learning.

    Science.gov (United States)

    de Carvalho Myskiw, Jociane; Benetti, Fernando; Izquierdo, Iván

    2013-01-15

    Extinction of contextual fear in rats is enhanced by exposure to a novel environment at 1-2 h before or 1 h after extinction training. This effect is antagonized by administration of protein synthesis inhibitors anisomycin and rapamycin into the hippocampus, but not into the amygdala, immediately after either novelty or extinction training, as well as by the gene expression blocker 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole administered after novelty training, but not after extinction training. Thus, this effect can be attributed to a mechanism similar to synaptic tagging, through which long-term potentiation can be enhanced by other long-term potentiations or by exposure to a novel environment in a protein synthesis-dependent fashion. Extinction learning produces a tag at the appropriate synapses, whereas novelty learning causes the synthesis of plasticity-related proteins that are captured by the tag, strengthening the synapses that generated this tag.

  14. Extinction of Harrington's mountain goat

    International Nuclear Information System (INIS)

    Mead, J.I.; Martin, P.S.; Euler, R.C.; Long, A.; Jull, A.J.T.; Toolin, L.J.; Donahue, D.J.; Linick, T.W.

    1986-01-01

    Keratinous horn sheaths of the extinct Harrington's mountain goat, Oreamnos harringtoni, were recovered at or near the surface of dry caves of the Grand Canyon, Arizona. Twenty-three separate specimens from two caves were dated nondestructively by the tandem accelerator mass spectrometer (TAMS). Both the TAMS and the conventional dates indicate that Harrington's mountain goat occupied the Grand Canyon for at least 19,000 years prior to becoming extinct by 11,160 +/- 125 radiocarbon years before present. The youngest average radiocarbon dates on Shasta ground sloths, Nothrotheriops shastensis, from the region are not significantly younger than those on extinct mountain goats. Rather than sequential extinction with Harrington's mountain goat disappearing from the Grand Canyon before the ground sloths, as one might predict in view of evidence of climatic warming at the time, the losses were concurrent. Both extinctions coincide with the regional arrival of Clovis hunters

  15. Extinction of metal fires

    International Nuclear Information System (INIS)

    Mellottee, H.

    1977-01-01

    The main points of a large bibliography on liquid and solid metal fires are set out. The various methods used to fight these fires are presented; covering by powders is specially emphasized. Since this method has promising results, the various possible techniques, extinction by cooling the metal, by blanketing, by formation of a continuous insulating layer (by fusion or pyrolysis of a powder) or by a surface reaction between powder and metal are studied. The conditions of conservation and use of powders are outlined, then the various powders are described: inert powders, powders undergoing a physical transformation (fusion or vitrification of an organic compound, fusion of eutectic inorganic mixtures), multiple effect powders. Precise examples are quoted [fr

  16. Measuring Extinction with ALE

    Science.gov (United States)

    Zimmer, Peter C.; McGraw, J. T.; Gimmestad, G. G.; Roberts, D.; Stewart, J.; Smith, J.; Fitch, J.

    2007-12-01

    ALE (Astronomical LIDAR for Extinction) is deployed at the University of New Mexico's (UNM) Campus Observatory in Albuquerque, NM. It has begun a year-long testing phase prior deployment at McDonald Observatory in support of the CCD/Transit Instrument II (CTI-II). ALE is designed to produce a high-precision measurement of atmospheric absorption and scattering above the observatory site every ten minutes of every moderately clear night. LIDAR (LIght Detection And Ranging) is the VIS/UV/IR analog of radar, using a laser, telescope and time-gated photodetector instead of a radio transmitter, dish and receiver. In the case of ALE -- an elastic backscatter LIDAR -- 20ns-long, eye-safe laser pulses are launched 2500 times per second from a 0.32m transmitting telescope co-mounted with a 50mm short-range receiver on an alt-az mounted 0.67m long-range receiver. Photons from the laser pulse are scattered and absorbed as the pulse propagates through the atmosphere, a portion of which are scattered into the field of view of the short- and long-range receiver telescopes and detected by a photomultiplier. The properties of a given volume of atmosphere along the LIDAR path are inferred from both the altitude-resolved backscatter signal as well as the attenuation of backscatter signal from altitudes above it. We present ALE profiles from the commissioning phase and demonstrate some of the astronomically interesting atmospheric information that can be gleaned from these data, including, but not limited to, total line-of-sight extinction. This project is funded by NSF Grant 0421087.

  17. Prefrontal single-unit firing associated with deficient extinction in mice

    Science.gov (United States)

    Fitzgerald, Paul J; Whittle, Nigel; Flynn, Shaun M; Graybeal, Carolyn; Pinard, Courtney; Gunduz-Cinar, Ozge; Kravitz, Alexxai; Singewald, Nicolas; Holmes, Andrew

    2014-01-01

    The neural circuitry mediating fear extinction has been increasingly well studied and delineated. The rodent infralimbic subregion (IL) of the ventromedial prefrontal cortex (vmPFC) has been found to promote extinction, whereas the prelimbic cortex (PL) demonstrates an opposing, pro-fear, function. Studies employing in vivo electrophysiological recordings have observed that while increased IL single-unit firing and bursting predicts robust extinction retrieval, increased PL firing can correlate with sustained fear and poor extinction. These relationships between single-unit firing and extinction do not hold under all experimental conditions, however. In the current study, we further investigated the relationship between vmPFC and PL single-unit firing and extinction using inbred mouse models of intact (C57BL/6J, B6) and deficient (129S1/SvImJ, S1) extinction strains. Simultaneous single-unit recordings were made in the PL and vmPFC (encompassing IL) as B6 and S1 mice performed extinction training and retrieval. Impaired extinction retrieval in S1 mice was associated with elevated PL single-unit firing, as compared to firing in extinguishing B6 mice, consistent with the hypothesized pro-fear contribution of PL. Analysis of local field potentials also revealed significantly higher gamma power in the PL of Sthan B6 mice during extinction training and retrieval. In the vmPFC, impaired extinction in S1 mice was also associated with exaggerated single-unit firing, relative to B6 mice. This is in apparent contradiction to evidence that IL activity promotes extinction, but could reflect a (failed) compensatory effort by the vmPFC to mitigate fear-promoting activity in other regions, such as the PL or amygdala. In support of this hypothesis, augmenting IL activity via direct infusion of the GABAA receptor antagonist picrotoxin rescued impaired extinction retrieval in S1 mice. Chronic fluoxetine treatment produced modest reductions in fear during extinction retrieval and

  18. Jet Car Track Site

    Data.gov (United States)

    Federal Laboratory Consortium — Located in Lakehurst, New Jersey, the Jet Car Track Site supports jet cars with J57 engines and has a maximum jet car thrust of 42,000 pounds with a maximum speed of...

  19. Jet Crackle

    Science.gov (United States)

    2015-06-23

    crackle is correlated to signals with intermittent periods of steepened shock-like waves followed by weaker, longer, rounded rarefaction regions, but to...turbulence is concentrated in a weakly curved (for a typical round jet) shear layer between the high-speed potential core flow and the surrounding co-flow...decreases into the acoustic field. The effect of varying dc between −0.1 and −0.003δm(t)/∆U causes the Nδm/Lx curves to shift downward as fewer waves

  20. Does red noise increase or decrease extinction risk? Single extreme events versus series of unfavorable conditions.

    Science.gov (United States)

    Schwager, Monika; Johst, Karin; Jeltsch, Florian

    2006-06-01

    Recent theoretical studies have shown contrasting effects of temporal correlation of environmental fluctuations (red noise) on the risk of population extinction. It is still debated whether and under which conditions red noise increases or decreases extinction risk compared with uncorrelated (white) noise. Here, we explain the opposing effects by introducing two features of red noise time series. On the one hand, positive autocorrelation increases the probability of series of poor environmental conditions, implying increasing extinction risk. On the other hand, for a given time period, the probability of at least one extremely bad year ("catastrophe") is reduced compared with white noise, implying decreasing extinction risk. Which of these two features determines extinction risk depends on the strength of environmental fluctuations and the sensitivity of population dynamics to these fluctuations. If extreme (catastrophic) events can occur (strong noise) or sensitivity is high (overcompensatory density dependence), then temporal correlation decreases extinction risk; otherwise, it increases it. Thus, our results provide a simple explanation for the contrasting previous findings and are a crucial step toward a general understanding of the effect of noise color on extinction risk.

  1. Penatalaksanaan Repair Palatoplasty dengan Teknik Furlow Double Opposing Z Plasty

    Directory of Open Access Journals (Sweden)

    Pingky Krisna Arindra

    2015-06-01

    metode Furlow double opposing z plasty dengan kombinasi insisi lateral, dan didapatkan hasil menutupnya celah di palatum mole sampai dengan uvula. Telah dilakukan operasi repair palatoplasi dengan metode Furlow double opposing z plasty. Teknik ini dilakukan untuk menghindari insisi yang terlalu luas dikarenakan terdapatnya jaringan fibrous yang tebal pada mukosa palatum pasca operasi sebelumnya. Tujuan studi kasus adalah untuk mengetahui kemampuan teknik Furlow Double Opposing Z Plasty sebagai prosedur repair palatoplasty.   Repair Palatoplasty Management with Furlow Double Opposing Z Plasty Technique. Cases of cleft lip and palate are one of the deformity disorders that often occur. There are variety of clinical appearance ranging from incomplete to complete cases. Clinical appearance with different width requires proper surgical technique. Patients with cleft lip and palate had undergone surgical intervention, so that they needed surgical correction to repair the result or failure of the previous surgery. A Four year old boy complain there was cleft on the soft palate. The patient was diagnosed with labiognatopalatoscisis. The patient had undergone two stages of cleft lip surgery and twice of cleft palate surgery with pushback method and repair with z plasty, however the result was unsatisfactory. Further, the patient underwent repair palatoplasty surgery with Furlow double opposing z plasty method combined with lateral relaxing insicion. The result in the post surgery was the closure of cleft soft palate up to uvula. Repair palataplasty surgery has been done with Furlow double opposing z plasty method. This technique could avoid extended incision due to thick fibrous tissue on the palatum mucosa as the result of serial previous surgery. The aim of this case case study is to determine the technical capabilities of Furlow Double Opposing Z Plasty as palatoplasty repair procedure.

  2. Genetic sex determination and extinction.

    Science.gov (United States)

    Hedrick, Philip W; Gadau, Jürgen; Page, Robert E

    2006-02-01

    Genetic factors can affect the probability of extinction either by increasing the effect of detrimental variants or by decreasing the potential for future adaptive responses. In a recent paper, Zayed and Packer demonstrate that low variation at a specific locus, the complementary sex determination (csd) locus in Hymenoptera (ants, bees and wasps), can result in a sharply increased probability of extinction. Their findings illustrate situations in which there is a feedback process between decreased genetic variation at the csd locus owing to genetic drift and decreased population growth, resulting in an extreme type of extinction vortex for these ecologically important organisms.

  3. Reconsidering the extinction of ichthyosaurs

    OpenAIRE

    Fischer, Valentin

    2010-01-01

    Despite their extreme adaptation to life in open sea, ichthyosaurs were one of the first major groups of post-Triassic marine reptiles to disappear, at the end of Cenomanian, whereas plesiosaurs, mosasaurs and numerous families of marine crocodiles and sea turtles disappeared during the Cretaceous/Paleocene Extinction Event. It has been proposed that unique biological factors drove ichthyosaurs to extinction, namely a break in the food chain at the level of belemnites or a progressive ecologi...

  4. The Sixth Great Mass Extinction

    Science.gov (United States)

    Wagler, Ron

    2012-01-01

    Five past great mass extinctions have occurred during Earth's history. Humanity is currently in the midst of a sixth, human-induced great mass extinction of plant and animal life (e.g., Alroy 2008; Jackson 2008; Lewis 2006; McDaniel and Borton 2002; Rockstrom et al. 2009; Rohr et al. 2008; Steffen, Crutzen, and McNeill 2007; Thomas et al. 2004;…

  5. Thermal Transgressions and Phanerozoic Extinctions

    Science.gov (United States)

    Worsley, T. R.; Kidder, D. L.

    2007-12-01

    A number of significant Phanerozoic extinctions are associated with marine transgressions that were probably driven by rapid ocean warming. The conditions associated with what we call thermal transgressions are extremely stressful to life on Earth. The Earth system setting associated with end-Permian extinction exemplifies an end-member case of our model. The conditions favoring extreme warmth and sea-level increases driven by thermal expansion are also conducive to changes in ocean circulation that foster widespread anoxia and sulfidic subsurface ocean waters. Equable climates are characterized by reduced wind shear and weak surface ocean circulation. Late Permian and Early Triassic thermohaline circulation differs considerably from today's world, with minimal polar sinking and intensified mid-latitude sinking that delivers sulfate from shallow evaporative areas to deeper water where it is reduced to sulfide. Reduced nutrient input to oceans from land at many of the extinction intervals results from diminished silicate weathering and weakened delivery of iron via eolian dust. The falloff in iron-bearing dust leads to minimal nitrate production, weakening food webs and rendering faunas and floras more susceptible to extinction when stressed. Factors such as heat, anoxia, ocean acidification, hypercapnia, and hydrogen sulfide poisoning would significantly affect these biotas. Intervals of tectonic quiescence set up preconditions favoring extinctions. Reductions in chemical silicate weathering lead to carbon dioxide buildup, oxygen drawdown, nutrient depletion, wind and ocean current abatement, long-term global warming, and ocean acidification. The effects of extinction triggers such as large igneous provinces, bolide impacts, and episodes of sudden methane release are more potent against the backdrop of our proposed preconditions. Extinctions that have characteristics we call for in the thermal transgressions include the Early Cambrian Sinsk event, as well as

  6. Jet inclusive cross sections

    International Nuclear Information System (INIS)

    Del Duca, V.

    1992-11-01

    Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons

  7. Global Implications of late Pleistocene Megafaunal Extinctions in the Holarctic

    Science.gov (United States)

    Cooper, Alan; Turney, Chris

    2017-04-01

    Improved resolution data from radiocarbon, climate and ancient DNA studies of megafauna and humans is providing the first ability to disentangle the roles of climate change and human impact in the Late Pleistocene megafaunal extinctions. In the Holarctic we find that megafaunal populations underwent repeated local or global extinctions apparently associated with abrupt, centennial to millennial duration warming events (Dansgaard-Oeschger interstadials). Importantly, the extinction events took place both before and after the arrival of modern humans in the landscape. Here we look at the possible role of human activity in Holarctic and suggest it may be through the disruption of metapopulation processes which stabilize ecosystems and may have evolved to provide resilience to rapid and frequent climate shifts in the past. The observed relationship between climate and humans on megafaunal populations may provide a model for global extinction. Fortunately in this regard, the rapid movement of the first Native Americans throughout both American continents during the Last Deglaciation provides a powerful and unique model system for testing the competing roles on extinction because the opposing climate trends in each hemisphere at the time. Here we show that while megafaunal extinctions were associated with warming trends in both cases, the out-of-phase climate patterns caused the sequence and timing of events to be mirrored, providing a unique high-resolution view of the interactions of human colonization and rapid climate change on megafaunal ecosystems, with implications for future warming scenarios. References: Cooper, A., Turney, C., Hughen, K.A., Brook, B.W., McDonald, H.G., Bradshaw, C.J.A., 2015. Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover. Science 349, 602-606. Metcalf, J.L., Turney, C., Barnett, R., Martin, F., Bray, S.C., Vilstrup, J.T., Orlando, L., Salas-Gismondi, R., Loponte, D., Medina, M., De Nigris, M., Civalero, T., Fern

  8. Consumers and Makers: Exploring Opposing Paradigms of Millennial College Readiness

    Science.gov (United States)

    Jackson, Matthew

    2017-01-01

    The political and technological circumstances of the past two decades have culminated in opposing epistemic paradigms of college readiness, where millennial students' conceptual understanding of "learning" is both narrowed to meet the demands of school systems bound to accountability and amplified by a rapidly evolving digital world. The…

  9. Opposing Amygdala and Ventral Striatum Connectivity during Emotion Identification

    Science.gov (United States)

    Satterthwaite, Theodore D.; Wolf, Daniel H.; Pinkham, Amy E.; Ruparel, Kosha; Elliott, Mark A.; Valdez, Jeffrey N.; Overton, Eve; Seubert, Janina; Gur, Raquel E.; Gur, Ruben C.; Loughead, James

    2011-01-01

    Lesion and electrophysiological studies in animals provide evidence of opposing functions for subcortical nuclei such as the amygdala and ventral striatum, but the implications of these findings for emotion identification in humans remain poorly described. Here we report a high-resolution fMRI study in a sample of 39 healthy subjects who performed…

  10. Jet Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.; O'Hara, G.W.; Pollard, I.E.

    1988-07-01

    The paper presents the Jet Joint Undertaking annual report 1987. A description is given of the JET and Euratom and International Fusion Programmes. The technical status of JET is outlined, including the development and improvements made to the system in 1987. The results of JET Operation in 1987 are described within the areas of: density effects, temperature improvements, energy confinement studies and other material effects. The contents also contain a summary of the future programme of JET. (U.K.)

  11. The extinction of the dinosaurs.

    Science.gov (United States)

    Brusatte, Stephen L; Butler, Richard J; Barrett, Paul M; Carrano, Matthew T; Evans, David C; Lloyd, Graeme T; Mannion, Philip D; Norell, Mark A; Peppe, Daniel J; Upchurch, Paul; Williamson, Thomas E

    2015-05-01

    Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  12. General relativistic study of astrophysical jets with internal shocks

    Science.gov (United States)

    Vyas, Mukesh K.; Chattopadhyay, Indranil

    2017-08-01

    We explore the possibility of the formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry (θ = 0) in a Schwarzschild metric. We use two models for the jet geometry: (I) a conical geometry and (II) a geometry with non-conical cross-section. A jet with conical geometry has a smooth flow, while the jet with non-conical cross-section undergoes multiple sonic points and even standing shock. The jet shock becomes stronger, as the shock location is situated farther from the central black hole. Jets with very high energy and very low energy do not harbour shocks, but jets with intermediate energies do harbour shocks. One advantage of these shocks, as opposed to shocks mediated by external medium, is that these shocks have no effect on the jet terminal speed, but may act as possible sites for particle acceleration. Typically, a jet with specific energy 1.8c2 will achieve a terminal speed of v∞ = 0.813c for jet with any geometry, where, c is the speed of light in vacuum. But for a jet of non-conical cross-section for which the length scale of the inner torus of the accretion disc is 40rg, then, in addition, a steady shock will form at rsh ˜ 7.5rg and compression ratio of R ˜ 2.7. Moreover, electron-proton jet seems to harbour the strongest shock. We will discuss possible consequences of such a scenario.

  13. The atmospheric extinction of light

    International Nuclear Information System (INIS)

    Hughes, Stephen W; Powell, Sean; Carroll, Joshua; Cowley, Michael

    2016-01-01

    An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm −1 respectively and 0.032, 0.037 and 0.092 cm −1 for the Picotech Dr. DAQ ADC. (paper)

  14. Infectious Disease, Endangerment, and Extinction

    Science.gov (United States)

    MacPhee, Ross D. E.; Greenwood, Alex D.

    2013-01-01

    Infectious disease, especially virulent infectious disease, is commonly regarded as a cause of fluctuation or decline in biological populations. However, it is not generally considered as a primary factor in causing the actual endangerment or extinction of species. We review here the known historical examples in which disease has, or has been assumed to have had, a major deleterious impact on animal species, including extinction, and highlight some recent cases in which disease is the chief suspect in causing the outright endangerment of particular species. We conclude that the role of disease in historical extinctions at the population or species level may have been underestimated. Recent methodological breakthroughs may lead to a better understanding of the past and present roles of infectious disease in influencing population fitness and other parameters. PMID:23401844

  15. Vector boson tagged jets and jet substructure

    Directory of Open Access Journals (Sweden)

    Vitev Ivan

    2018-01-01

    Full Text Available In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. Z0-tagging and γ-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at √sNN = 5.02 TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

  16. Understanding jet noise.

    Science.gov (United States)

    Karabasov, S A

    2010-08-13

    Jets are one of the most fascinating topics in fluid mechanics. For aeronautics, turbulent jet-noise modelling is particularly challenging, not only because of the poor understanding of high Reynolds number turbulence, but also because of the extremely low acoustic efficiency of high-speed jets. Turbulent jet-noise models starting from the classical Lighthill acoustic analogy to state-of-the art models were considered. No attempt was made to present any complete overview of jet-noise theories. Instead, the aim was to emphasize the importance of sound generation and mean-flow propagation effects, as well as their interference, for the understanding and prediction of jet noise.

  17. Very forward jet, Mueller Navelet jets and jet gap jet measurements in CMS

    CERN Document Server

    Cerci, Salim

    2018-01-01

    The measurements of very forward jet, Mueller-Navelet jets and jet-gap-jet events are presented for different collision energies. The analyses are based on data collected with the CMS detector at the LHC. Jets are defined through the anti-$k_\\mathrm{t}$ clustering algorithm for different cone sizes. Jet production studies provide stringent tests of quantum chromodynamics (QCD) and contribute to tune Monte Carlo (MC) simulations and phenomenological models. The measurements are compared to predictions from various Monte Carlo event generators.

  18. Opposing flow in square porous annulus: Influence of Dufour effect

    International Nuclear Information System (INIS)

    Athani, Abdulgaphur; Al-Rashed, Abdullah A. A. A.; Khaleed, H. M. T.

    2016-01-01

    Heat and mass transfer in porous medium is very important area of research which is also termed as double diffusive convection or thermo-solutal convection. The buoyancy ratio which is the ratio of thermal to concentration buoyancy can have negative values thus leading to opposing flow. This article is aimed to study the influence of Dufour effect on the opposing flow in a square porous annulus. The partial differential equations that govern the heat and mass transfer behavior inside porous medium are solved using finite element method. A three node triangular element is used to divide the porous domain into smaller elements. Results are presented with respect to geometric and physical parameters such as duct diameter ratio, Rayleigh number, radiation parameter etc. It is found that the heat transfer increase with increase in Rayleigh number and radiation parameter. It is observed that Dufour coefficient has more influence on velocity profile.

  19. Opposing flow in square porous annulus: Influence of Dufour effect

    Energy Technology Data Exchange (ETDEWEB)

    Athani, Abdulgaphur, E-mail: abbu.bec@gmail.com [Dept. of Mechanical Engineering, Anjuman Institute of Technology & Management, Bhatkal (India); Al-Rashed, Abdullah A. A. A., E-mail: aa.alrashed@paaet.edu.kw [Dept. of Automotive and Marine Engineering Technology, College of Technological Studies, The Public Authority for Applied Education and Training (Kuwait); Khaleed, H. M. T., E-mail: khalid-tan@yahoo.com [Dept of Mechanical Engineering, Faculty of Engineering, Islamic University, Madinah Munawwarra (Saudi Arabia)

    2016-06-21

    Heat and mass transfer in porous medium is very important area of research which is also termed as double diffusive convection or thermo-solutal convection. The buoyancy ratio which is the ratio of thermal to concentration buoyancy can have negative values thus leading to opposing flow. This article is aimed to study the influence of Dufour effect on the opposing flow in a square porous annulus. The partial differential equations that govern the heat and mass transfer behavior inside porous medium are solved using finite element method. A three node triangular element is used to divide the porous domain into smaller elements. Results are presented with respect to geometric and physical parameters such as duct diameter ratio, Rayleigh number, radiation parameter etc. It is found that the heat transfer increase with increase in Rayleigh number and radiation parameter. It is observed that Dufour coefficient has more influence on velocity profile.

  20. Two Opposing Effects (Yin and Yang) Determine Cancer Progression.

    Science.gov (United States)

    Huang, Shujun; Kurubanjerdjit, Nilubon; Xu, Wayne

    2017-01-01

    In this review, we introduce a new vision of cancer describing opposing effects that control progression. Cancer is a paradigm of opposing of "Yin" and "Yang," with Yin being the effect to promote cancer and Yang that to maintain the normal state. This Yin Yang hypothesis has been used to select Yin and Yang genes to develop multigene signatures for determining prognosis in lung and breast cancer. Most of the Yin genes are involved in cell survival, growth, and proliferation, whereas most Yang genes are involved in cell apoptosis. Furthermore, Yin and Yang pathways have been identified in breast cancer and compounds that can inhibit the Yin pathways or activate the Yang pathways have been examined, suggesting a new promising targeting therapy for cancer. We are building a Yin Yang model to represent the dynamic change of Yin and Yang genes and pathways.

  1. Transport synthetic acceleration with opposing reflecting boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zika, M R; Adams, M L

    2000-02-01

    The transport synthetic acceleration (TSA) scheme is extended to problems with opposing reflecting boundary conditions. This synthetic method employs a simplified transport operator as its low-order approximation. A procedure is developed that allows the use of the conjugate gradient (CG) method to solve the resulting low-order system of equations. Several well-known transport iteration algorithms are cast in a linear algebraic form to show their equivalence to standard iterative techniques. Source iteration in the presence of opposing reflecting boundary conditions is shown to be equivalent to a (poorly) preconditioned stationary Richardson iteration, with the preconditioner defined by the method of iterating on the incident fluxes on the reflecting boundaries. The TSA method (and any synthetic method) amounts to a further preconditioning of the Richardson iteration. The presence of opposing reflecting boundary conditions requires special consideration when developing a procedure to realize the CG method for the proposed system of equations. The CG iteration may be applied only to symmetric positive definite matrices; this condition requires the algebraic elimination of the boundary angular corrections from the low-order equations. As a consequence of this elimination, evaluating the action of the resulting matrix on an arbitrary vector involves two transport sweeps and a transmission iteration. Results of applying the acceleration scheme to a simple test problem are presented.

  2. Mass Extinctions and Supernova Explosions

    Science.gov (United States)

    Korschinek, Gunther

    A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation or the direct exposure of lethal X-rays. Another indirect effect is cloud formation, induced by cosmic rays in the atmosphere which result in a drop in the Earth's temperature, causing major glaciations of the Earth. The discovery of highly intensive gamma-ray bursts (GRBs), which could be connected to SNe, initiated further discussions on possible life-threatening events in the Earth's history. The probability that GRBs hit the Earth is very low. Nevertheless, a past interaction of Earth with GRBs and/or SNe cannot be excluded and might even have been responsible for past extinction events.

  3. Modeling Population Growth and Extinction

    Science.gov (United States)

    Gordon, Sheldon P.

    2009-01-01

    The exponential growth model and the logistic model typically introduced in the mathematics curriculum presume that a population grows exclusively. In reality, species can also die out and more sophisticated models that take the possibility of extinction into account are needed. In this article, two extensions of the logistic model are considered,…

  4. New theories about ancient extinctions

    Science.gov (United States)

    Spall, H.

    1986-01-01

    The abrupt disappearance of all the dinosaurs about 65 million years ago, along with perhaps half the plant species and other animals, has been one of the great geological mysteries. Clues to the cause of these extinctions have been scarce and open to many interpretations.

  5. Extinction debt on oceanic islands

    DEFF Research Database (Denmark)

    Triantis, Kostas A.; Borges, Paulo A. V.; Ladle, Richard J.

    2010-01-01

    the magnitude of such future extinction events has been hampered by potentially inaccurate assumptions about the slope of species-area relationships, which are habitat- and taxon-specific. We overcome this challenge by applying a method that uses the historical sequence of deforestation in the Azorean Islands...

  6. The currency and tempo of extinction.

    Science.gov (United States)

    Regan, H M; Lupia, R; Drinnan, A N; Burgman, M A

    2001-01-01

    This study examines estimates of extinction rates for the current purported biotic crisis and from the fossil record. Studies that compare current and geological extinctions sometimes use metrics that confound different sources of error and reflect different features of extinction processes. The per taxon extinction rate is a standard measure in paleontology that avoids some of the pitfalls of alternative approaches. Extinction rates reported in the conservation literature are rarely accompanied by measures of uncertainty, despite many elements of the calculations being subject to considerable error. We quantify some of the most important sources of uncertainty and carry them through the arithmetic of extinction rate calculations using fuzzy numbers. The results emphasize that estimates of current and future rates rely heavily on assumptions about the tempo of extinction and on extrapolations among taxa. Available data are unlikely to be useful in measuring magnitudes or trends in current extinction rates.

  7. EARTH SCIENCE: Did Volcanoes Drive Ancient Extinctions?

    Science.gov (United States)

    Kerr, R A

    2000-08-18

    With the publication in recent weeks of two papers on a mass extinction 183 million years ago, researchers can add five suggestive cases to the list of extinctions with known causes. These extinctions coincide with massive outpourings of lava, accompanied by signs that global warming threw the ocean-atmosphere system out of whack. Although no one can yet pin any of these mass extinctions with certainty on the volcanic eruptions, scientists say it's unlikely that they're all coincidences.

  8. An investigation of the interstellar extinction

    International Nuclear Information System (INIS)

    Roche, P.F.; Aitken, D.K.; Melbourne Univ., Point Cook

    1984-01-01

    The 10 μm extinction towards six WC8 or WC9 Wolf-Rayet stars is investigated. All objects show smooth dust emission suffering silicate absorption with depths well correlated with the extinction in the visible. The de-reddened spectra are well represented by emission from featureless grain components, possibly from iron or carbon grains. The extinction to the stars is found to be dominantly interstellar in origin with little extinction from the circumstellar shell. (author)

  9. Jet Vertex Charge Reconstruction

    CERN Document Server

    Nektarijevic, Snezana; The ATLAS collaboration

    2015-01-01

    A newly developed algorithm called the jet vertex charge tagger, aimed at identifying the sign of the charge of jets containing $b$-hadrons, referred to as $b$-jets, is presented. In addition to the well established track-based jet charge determination, this algorithm introduces the so-called \\emph{jet vertex charge} reconstruction, which exploits the charge information associated to the displaced vertices within the jet. Furthermore, the charge of a soft muon contained in the jet is taken into account when available. All available information is combined into a multivariate discriminator. The algorithm has been developed on jets matched to generator level $b$-hadrons provided by $t\\bar{t}$ events simulated at $\\sqrt{s}$=13~TeV using the full ATLAS detector simulation and reconstruction.

  10. Further Evidence of Auditory Extinction in Aphasia

    Science.gov (United States)

    Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim

    2013-01-01

    Purpose: Preliminary research ( Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Method: Seventeen IWA (M[subscript age] = 53.19 years)…

  11. Delving into QCD jets

    International Nuclear Information System (INIS)

    Konishi, K.

    1980-01-01

    The author discusses, in an introductory fashion, the latest developments in the study of hadronic jets produced in hard processes, based on perturbative QCD. Emphasis is on jet calculus (and its applications and generalizations), and on the appearance of a parton-like consistent, over-all picture of jet evolution in momentum, colour, and real space-time. (Auth.)

  12. Characterization of high speed synthetic jet actuators

    Science.gov (United States)

    Pikcilingis, Lucia

    Over the last 20 years, synthetic jets have been studied as a means for aerodynamic active flow control. Specifically, synthetic jets provide momentum transfer with zero-net mass flux, which has been proven to be effective for controlling flow fields. A synthetic jet is created by the periodic formation of vortex rings at its orifice due to the periodic motion of a piezoelectric disk(s). The present study seeks to optimize the performance of a synthetic jet actuator by utilizing different geometrical parameters such as disk thickness, orifice width and length, cavity height and cavity diameter, and different input parameters such as driving voltage and frequency. Two apparatuses were used with a cavity diameter of either 80 mm or 160 mm. Piezoelectric-based disks were provided by the Mide Corporation. Experiments were conducted using several synthetic jet apparatuses designed for various geometrical parameters utilizing a dual disk configuration. Velocity and temperature measurements were acquired at the center of the synthetic jet orifice using a temperature compensated hotwire and thermocouple probe. The disk(s) displacement was measured at the center of the disk with a laser displacement sensor. It was shown that the synthetic jets, having the 80 mm cavity diameter, are capable of exceeding peak velocities of 200 m/s with a relatively large orifice of dimensions AR = 12, hc* = 3, and hn* = 4. In addition, the conditions at which the disks were manufactured had minimal effect on the performance of the jet, except for the pair with overnight resting time as opposed to less than an hour resting time for the control units. Altering the tab style of the disks, where the tab allows the electrical circuit to be exposed for external power connection, showed that a thin fragile tab versus a tab of the same thickness as the disk has minimal effect on the performance but affects the durability of the disk due to the fragility or robustness of the tab. The synthetic jets

  13. Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX

    International Nuclear Information System (INIS)

    2010-01-01

    Jets from heavy ion collisions provide a measurement of the medium-induced parton energy loss and the in-medium fragmentation properties. The medium modification effects are determined by comparing to a p+p baseline measurement, but the high multiplicity background in a heavy ion collision inhibits the direct application of traditional jet reconstruction techniques and novel approaches are needed to deal with this environment. Alternatively, angular correlations between the hadronic fragments of energetic partons can be used to understand the hot dense matter produced in relativistic heavy ion collisions. The yield and shape modifications of the away side peaks as function of transverse momentum compared to p+p has been interpreted as a medium response to parton energy loss. Direct photon-hadron correlations are another excellent channel to study jets from heavy ion collisions. Photons do not interact strongly with the medium and thus the photon approximately balances the momentum of the opposing jet, allowing the measurement of the effective modification to the fragmentation function through jet energy loss in the medium.

  14. Numerical analyses of flashing jet structure and droplet size characteristics

    International Nuclear Information System (INIS)

    Duan Riqiang; Jiang Shengyao; Koshizuka, Seiichi; Oka, Yoshiaki; Yamaguchi, Akira; Takata, Takashi

    2006-01-01

    In this paper, flashing jets are numerically simulated using the MPS method. The boiling mode for flashing is identified as surface boiling mode, based on the postulation of jets from a short nozzle under high depressurization. The Homogeneous Non-equilibrium Relaxation Model (HRM) is used for calculating the evaporation rate of flashing. The numerical simulation results show that flashing jets comprise an inner intact core which is surrounded by two-phase droplet flow. The effect of degree of superheat on the jet topological geometry is investigated. With increasing degree of superheat, the topological shape of flashing jets evolves from cylindrical core for low degree of superheat to cone-shaped core for high degree of superheat, and meanwhile the extinction length comes to decrease and tends asymptotically constant as the injection temperature approaches the saturation temperature corresponding to the injection pressure. The analyses of the droplet size distribution engendered from primary breakup of flashing jets show that: two peaks exist for droplet size distribution at lower degree of superheat; however, merely one peak for higher degree of superheat. From droplet size distribution, it is revealed that the primary breakup mechanism of flashing jets can be attributed to dominant mechanical breakup mode plus enhancement via surface evaporation. (author)

  15. Predicting extinction rates in stochastic epidemic models

    International Nuclear Information System (INIS)

    Schwartz, Ira B; Billings, Lora; Dykman, Mark; Landsman, Alexandra

    2009-01-01

    We investigate the stochastic extinction processes in a class of epidemic models. Motivated by the process of natural disease extinction in epidemics, we examine the rate of extinction as a function of disease spread. We show that the effective entropic barrier for extinction in a susceptible–infected–susceptible epidemic model displays scaling with the distance to the bifurcation point, with an unusual critical exponent. We make a direct comparison between predictions and numerical simulations. We also consider the effect of non-Gaussian vaccine schedules, and show numerically how the extinction process may be enhanced when the vaccine schedules are Poisson distributed

  16. Reconsolidation or extinction: transcription factor switch in the determination of memory course after retrieval.

    Science.gov (United States)

    de la Fuente, Verónica; Freudenthal, Ramiro; Romano, Arturo

    2011-04-13

    In fear conditioning, aversive stimuli are readily associated with contextual features. A brief reexposure to the training context causes fear memory reconsolidation, whereas a prolonged reexposure induces memory extinction. The regulation of hippocampal gene expression plays a key role in contextual memory consolidation and reconsolidation. However, the mechanisms that determine whether memory will reconsolidate or extinguish are not known. Here, we demonstrate opposing roles for two evolutionarily related transcription factors in the mouse hippocampus. We found that nuclear factor-κB (NF-κB) is required for fear memory reconsolidation. Conversely, calcineurin phosphatase inhibited NF-κB and induced nuclear factor of activated T-cells (NFAT) nuclear translocation in the transition between reconsolidation and extinction. Accordingly, the hippocampal inhibition of both calcineurin and NFAT independently impaired memory extinction, whereas inhibition of NF-κB enhanced memory extinction. These findings represent the first insight into the molecular mechanisms that determine memory reprocessing after retrieval, supporting a transcriptional switch that directs memory toward reconsolidation or extinction. The precise molecular characterization of postretrieval processes has potential importance to the development of therapeutic strategies for fear memory disorders.

  17. Extinction risk escalates in the tropics.

    Directory of Open Access Journals (Sweden)

    Jana C Vamosi

    Full Text Available The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction and we discuss mechanisms that may reconcile this apparent contradiction.

  18. Extinction risk escalates in the tropics.

    Science.gov (United States)

    Vamosi, Jana C; Vamosi, Steven M

    2008-01-01

    The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change) are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction) and we discuss mechanisms that may reconcile this apparent contradiction.

  19. Rescaling of temporal expectations during extinction

    Science.gov (United States)

    Drew, Michael R.; Walsh, Carolyn; Balsam, Peter D

    2016-01-01

    Previous research suggests that extinction learning is temporally specific. Changing the CS duration between training and extinction can facilitate the loss of the CR within the extinction session but impairs long-term retention of extinction. In two experiments using conditioned magazine approach with rats, we examined the relation between temporal specificity of extinction and CR timing. In Experiment 1 rats were trained on a 12-s, fixed CS-US interval and then extinguished with CS presentations that were 6, 12, or 24 s in duration. The design of Experiment 2 was the same except rats were trained using partial rather than continuous reinforcement. In both experiments, extending the CS duration in extinction facilitated the diminution of CRs during the extinction session, but shortening the CS duration failed to slow extinction. In addition, extending (but not shortening) the CS duration caused temporal rescaling of the CR, in that the peak CR rate migrated later into the trial over the course of extinction training. This migration partially accounted for the faster loss of the CR when the CS duration was extended. Results are incompatible with the hypothesis that extinction is driven by cumulative CS exposure and suggest that temporally extended nonreinforced CS exposure reduces conditioned responding via temporal displacement rather than through extinction per se. PMID:28045291

  20. Extinction Coefficient of Gold Nanostars.

    Science.gov (United States)

    de Puig, Helena; Tam, Justina O; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly

    2015-07-30

    Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 10 8 to 26.8 × 10 8 M -1 cm -1 . Measured values correlate with those obtained from theoretical models of the NStars using the discrete dipole approximation (DDA), which we use to simulate the extinction spectra of the nanostars. Finally, because NStars are typically used in biological applications, we conjugate DNA and antibodies to the NStars and calculate the footprint of the bound biomolecules.

  1. Dinasour extinction and volcanic activity

    Science.gov (United States)

    Gledhill, J. A.

    There is at present some controversy about the reason for the mass extinction of dinosaurs and other forms of life at the end of the Cretaceous. A suggestion by Alvarez et al. [1980] that this was due to the collision of the earth with a meteorite 10 km or so in diameter has excited considerable interest [Silver and Schultz, 1982] and also some criticism [Stanley, 1984]. A recent publication [Wood, 1984] describing the catastrophic effects of a relatively minor lava flow in Iceland suggests that intense volcanic activity could have played a large part in the extinctions. In this letter it is pointed out that the Deccan lava flows in India took place in the appropriate time and may well have been of sufficient magnitude to be a major factor in the Cretaceous-Tertiary (C-T) boundary catastrophe.

  2. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.; Lallia, P.; O'Hara, G.W.; Pollard, I.E.

    1987-06-01

    The paper presents the annual report of the Joint European Torus (JET) Joint Undertaking, 1986. The report is divided into two parts: a part on the scientific and technical programme of the project, and a part setting out the administration and organisation of the Project. The first part includes: a summary of the main features of the JET apparatus, the JET experimental programme, the position of the Project in the overall Euratom programme, and how JET relates to other large fusion devices throughout the world. In addition, the technical status of JET is described, as well as the results of the JET operations in 1986. The final section of the first part outlines the proposed future programme of JET. (U.K.)

  3. Jet substructure in ATLAS

    CERN Document Server

    Miller, David W

    2011-01-01

    Measurements are presented of the jet invariant mass and substructure in proton-proton collisions at $\\sqrt{s} = 7$ TeV with the ATLAS detector using an integrated luminosity of 37 pb$^{-1}$. These results exercise the tools for distinguishing the signatures of new boosted massive particles in the hadronic final state. Two "fat" jet algorithms are used, along with the filtering jet grooming technique that was pioneered in ATLAS. New jet substructure observables are compared for the first time to data at the LHC. Finally, a sample of candidate boosted top quark events collected in the 2010 data is analyzed in detail for the jet substructure properties of hadronic "top-jets" in the final state. These measurements demonstrate not only our excellent understanding of QCD in a new energy regime but open the path to using complex jet substructure observables in the search for new physics.

  4. [Extinction and Reconsolidation of Memory].

    Science.gov (United States)

    Zuzina, A B; Balaban, P M

    2015-01-01

    Retrieval of memory followed by reconsolidation can strengthen a memory, while retrieval followed by extinction results in a decrease of memory performance due to weakening of existing memory or formation of a competing memory. In our study we analyzed the behavior and responses of identified neurons involved in the network underlying aversive learning in terrestrial snail Helix, and made an attempt to describe the conditions in which the retrieval of memory leads either to extinction or reconsolidation. In the network underlying the withdrawal behavior, sensory neurons, premotor interneurons, motor neurons, and modulatory for this network serotonergic neurons are identified and recordings from representatives of these groups were made before and after aversive learning. In the network underlying feeding behavior, the premotor modulatory serotonergic interneurons and motor neurons involved in motor program of feeding are identified. Analysis of changes in neural activity after aversive learning showed that modulatory neurons of feeding behavior do not demonstrate any changes (sometimes a decrease of responses to food was observed), while responses to food in withdrawal behavior premotor interneurons changed qualitatively, from under threshold EPSPs to spike discharges. Using a specific for serotonergic neurons neurotoxin 5,7-DiHT it was shown previously that the serotonergic system is necessary for the aversive learning, but is not necessary for maintenance and retrieval of this memory. These results suggest that the serotonergic neurons that are necessary as part of a reinforcement for developing the associative changes in the network may be not necessary for the retrieval of memory. The hypothesis presented in this review concerns the activity of the "reinforcement" serotonergic neurons that is suggested to be the gate condition for the choice between extinction/reconsolidation triggered by memory retrieval: if these serotonergic neurons do not respond during the

  5. Optimising Extinction of Conditioned Disgust.

    Science.gov (United States)

    Bosman, Renske C; Borg, Charmaine; de Jong, Peter J

    2016-01-01

    Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS)-only extinction procedures. The relatively strong resistance to extinction might be explained by disgust's adaptive function to motivate avoidance from contamination threats (pathogens) that cannot be readily detected and are invisible to the naked eye. Therefore, the mere visual presentation of unreinforced disgust eliciting stimuli might not be sufficient to correct a previously acquired threat value of the CS+. Following this, the current study tested whether the efficacy of CS-only exposure can be improved by providing additional safety information about the CS+. For the CSs we included two neutral items a pea soup and a sausage roll, whereas for the Unconditioned Stimulus (US) we used one video clip of a woman vomiting and a neutral one about glass blowing. The additional safety information was conveyed by allowing actual contact with the CS+ or by observing an actress eating the food items representing the CS+. When additional safety information was provided via allowing direct contact with the CS+, there was a relatively strong post-extinction increase in participants' willingness-to-eat the CS+. This beneficial effect was still evident at one-week follow up. Also self-reported disgust was lower at one-week follow up when additional safety information was provided. The current findings help explain why disgust is relatively insensitive to CS-only extinction procedures, and provide helpful starting points to improve interventions that are aimed to reduce distress in disgust-related psychopathology.

  6. Optimising Extinction of Conditioned Disgust.

    Directory of Open Access Journals (Sweden)

    Renske C Bosman

    Full Text Available Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS-only extinction procedures. The relatively strong resistance to extinction might be explained by disgust's adaptive function to motivate avoidance from contamination threats (pathogens that cannot be readily detected and are invisible to the naked eye. Therefore, the mere visual presentation of unreinforced disgust eliciting stimuli might not be sufficient to correct a previously acquired threat value of the CS+. Following this, the current study tested whether the efficacy of CS-only exposure can be improved by providing additional safety information about the CS+. For the CSs we included two neutral items a pea soup and a sausage roll, whereas for the Unconditioned Stimulus (US we used one video clip of a woman vomiting and a neutral one about glass blowing. The additional safety information was conveyed by allowing actual contact with the CS+ or by observing an actress eating the food items representing the CS+. When additional safety information was provided via allowing direct contact with the CS+, there was a relatively strong post-extinction increase in participants' willingness-to-eat the CS+. This beneficial effect was still evident at one-week follow up. Also self-reported disgust was lower at one-week follow up when additional safety information was provided. The current findings help explain why disgust is relatively insensitive to CS-only extinction procedures, and provide helpful starting points to improve interventions that are aimed to reduce distress in disgust-related psychopathology.

  7. Extinction Coefficient of Gold Nanostars

    OpenAIRE

    de Puig, Helena; Tam, Justina O.; Yen, Chun-Wan; Gehrke, Lee; Hamad-Schifferli, Kimberly

    2015-01-01

    Gold nanostars (NStars) are highly attractive for biological applications due to their surface chemistry, facile synthesis and optical properties. Here, we synthesize NStars in HEPES buffer at different HEPES/Au ratios, producing NStars of different sizes and shapes, and therefore varying optical properties. We measure the extinction coefficient of the synthesized NStars at their maximum surface plasmon resonances (SPR), which range from 5.7 × 108 to 26.8 × 108 M−1cm−1. Measured values correl...

  8. Cleft Palate Repair Using a Double Opposing Z-Plasty.

    Science.gov (United States)

    Moores, Craig; Shah, Ajul; Steinbacher, Derek M

    2016-07-01

    Cleft palate is a common congenital defect with several described surgical repairs. The most successful treatment modality remains a controversy. The goals of repair focus on achievement of normal speech and optimizing velopharyngeal function while minimizing both fistula formation and facial growth restriction. In this video, the authors demonstrate use of the double opposing Z-plasty technique in the repair of a Veau II type cleft palate. The video demonstrates the marking, incisions, dissection, and repair of the cleft. It also examines the use of von Langenbeck-type relaxing incisions and demonstrates a specific approach to the repair of this particular cleft. The authors believe that the Furlow double opposing Z-plasty with the von Langenbeck relaxing incision can provide the best postoperative outcome by combining the benefits of each individual operation. The Z-plasty technique works to correct the aberrant muscle of the soft palate while increasing the length of the palate. The authors believe that this results in better velopharyngeal function.

  9. Disentangling opposing effects of motivational states on pain perception

    Science.gov (United States)

    Geuter, Stephan; Cunningham, Jonathan T.; Wager, Tor D.

    2016-01-01

    Abstract Introduction: Although the motivation to avoid injury and pain is central to human and animal behavior, this goal compete priority with other homeostatic goals. Animal studies have shown that competing motivational states, such as thirst, reduce pain. However, such states may also induce negative mood, which in humans has been found to increase pain. These opposing effects complicate study of the effects of motivational states in humans. Objectives: To evaluate concurrent effects of motivational state competition and mood on pain ratings. Methods: We compared a thirst challenge against a control group and measured thirst and mood as potential mediators. Pain induced through contact heat stimulation on the left forearm and was tested at 3 time points: before group randomization, after thirst induction, and after rehydration. Results: Overall, the thirst group reported more pain when thirsty compared with baseline and controls. Mediation analyses showed evidence for two opposing effects. First, the thirst challenge increased negative mood and thirstiness, which was related to increased pain. Second, the thirst challenge produced a direct, pain-reducing effect. Conclusion: Competing motivational states reduce pain but also induce concurrent mood changes that can mask motivational state-related effects. PMID:27747310

  10. The role of medial prefrontal cortex in extinction and reinstatement of alcohol-seeking in rats.

    Science.gov (United States)

    Willcocks, Andrea L; McNally, Gavan P

    2013-01-01

    The prelimbic (PL) and infralimbic (IL) medial prefrontal cortex (mPFC) are thought to play opposing roles in drug-seeking behaviour. Specifically, the PL promotes drug-seeking whereas the IL is necessary for the inhibition of drug-seeking during extinction. We studied the roles of the PL, IL and dorsal peduncular PFC (DP) in the expression of context-induced reinstatement, reacquisition and extinction of alcoholic beer-seeking. In context-induced reinstatement (renewal), animals were trained to nosepoke for alcoholic beer (context A), extinguished (context B) and then tested in context A and B. In reacquisition, animals received the same instrumental training and extinction without any contextual manipulation. On test, alcoholic beer was again available and responding was compared with naive controls. Just prior to the test, rats received bilateral infusion of baclofen/muscimol into the PL, IL or DP. Reversible inactivation of the PL attenuated ABA renewal but augmented reacquisition. Reversible inactivation of IL had no effect on the reinstatement or reacquisition of alcoholic beer-seeking and had no effect on extinction expression (ABB and AAA). IL inactivation did, however, increase the latencies with which animals responded on test but only when animals were tested in the extinction context. DP inactivation had no effect on reinstatement or reacquisition. These studies are inconsistent with the view that PL and IL exert opposing effects on drug-seeking. Rather, they support the view that PL is important for retrieval of drug-seeking contingency information and that the use of contextual information is enhanced with IL manipulation. © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  11. Turbulent buoyant jets and plumes

    CERN Document Server

    Rodi, Wolfgang

    The Science & Applications of Heat and Mass Transfer: Reports, Reviews, & Computer Programs, Volume 6: Turbulent Buoyant Jets and Plumes focuses on the formation, properties, characteristics, and reactions of turbulent jets and plumes. The selection first offers information on the mechanics of turbulent buoyant jets and plumes and turbulent buoyant jets in shallow fluid layers. Discussions focus on submerged buoyant jets into shallow fluid, horizontal surface or interface jets into shallow layers, fundamental considerations, and turbulent buoyant jets (forced plumes). The manuscript then exami

  12. Invasions and extinctions reshape coastal marine food webs.

    Directory of Open Access Journals (Sweden)

    Jarrett E Byrnes

    Full Text Available The biodiversity of ecosystems worldwide is changing because of species loss due to human-caused extinctions and species gain through intentional and accidental introductions. Here we show that the combined effect of these two processes is altering the trophic structure of food webs in coastal marine systems. This is because most extinctions ( approximately 70% occur at high trophic levels (top predators and other carnivores, while most invasions are by species from lower trophic levels (70% macroplanktivores, deposit feeders, and detritivores. These opposing changes thus alter the shape of marine food webs from a trophic pyramid capped by a diverse array of predators and consumers to a shorter, squatter configuration dominated by filter feeders and scavengers. The consequences of the simultaneous loss of diversity at top trophic levels and gain at lower trophic levels is largely unknown. However, current research suggests that a better understanding of how such simultaneous changes in diversity can impact ecosystem function will be required to manage coastal ecosystems and forecast future changes.

  13. Extinction correction and synchrotron radiation

    International Nuclear Information System (INIS)

    Suortti, P.

    1983-01-01

    The primary extinction factor ysub(p) is defined as the ratio of the integrated reflection from a coherently diffracting domain to the integrated kinematical reflection from the same domain. When ysub(p) is larger than 0.5 it may be approximated by ysub(p)= exp[-(αdelta) 2 ], where α is about 0.5 and delta the average size of the coherent domain when measured in units of the extinction length Λ, delta = D/Λ. Transfer equations are applied to symmetrical Laue diffraction, and the reflectivity per unit length, sigma(epsilon) is solved from the measured reflecting ratio as a function of the rocking angle epsilon = theta -thetasub(B). Measurements with conventional x-ray sources are made on single crystal slabs of Be and Si using AgKβ, MoKα 1 and CuKα radiation. The primary extinction factor ysub(p)(epsilon) is solved from a point-by-point comparison of two measurements where the extinction length Λ is changed by varying the polarization and/or wavelength of the x-ray beam. The results show that primary and secondary extinction are strongly correlated, and that the customary assumption of independent size and orientation distributions of crystal mosaics is unjustified. The structure factors for Be and Si show close agreement with other recent measurements and calculations. The limitations of the method are discussed in length, particularly the effects of beam divergences and incoherence of the rays in the crystal. It is concluded that under typical experimental conditions the requirements of the theory are met. Practical limitations arising from the use of characteristic wavelengths and unpolarized radiation prohibit the use of the full potential of the method. The properties of a synchrotron radiation source are compared with a conventional x-ray source, and it is demonstrated that the experimental limitations can be removed by the use of synchrotron radiation. A diffraction experiment with synchrotron radiation is outlined, as well as generalization of the

  14. On jet substructure methods for signal jets

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Mrinal [Consortium for Fundamental Physics, School of Physics & Astronomy, University of Manchester,Oxford Road, Manchester M13 9PL (United Kingdom); Powling, Alexander [School of Physics & Astronomy, University of Manchester,Oxford Road, Manchester M13 9PL (United Kingdom); Siodmok, Andrzej [Institute of Nuclear Physics, Polish Academy of Sciences,ul. Radzikowskiego 152, 31-342 Kraków (Poland); CERN, PH-TH,CH-1211 Geneva 23 (Switzerland)

    2015-08-17

    We carry out simple analytical calculations and Monte Carlo studies to better understand the impact of QCD radiation on some well-known jet substructure methods for jets arising from the decay of boosted Higgs bosons. Understanding differences between taggers for these signal jets assumes particular significance in situations where they perform similarly on QCD background jets. As an explicit example of this we compare the Y-splitter method to the more recently proposed Y-pruning technique. We demonstrate how the insight we gain can be used to significantly improve the performance of Y-splitter by combining it with trimming and show that this combination outperforms the other taggers studied here, at high p{sub T}. We also make analytical estimates for optimal parameter values, for a range of methods and compare to results from Monte Carlo studies.

  15. Jet Substructure Without Trees

    Energy Technology Data Exchange (ETDEWEB)

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC /Stanford U., ITP

    2011-08-19

    We present an alternative approach to identifying and characterizing jet substructure. An angular correlation function is introduced that can be used to extract angular and mass scales within a jet without reference to a clustering algorithm. This procedure gives rise to a number of useful jet observables. As an application, we construct a top quark tagging algorithm that is competitive with existing methods. In preparation for the LHC, the past several years have seen extensive work on various aspects of collider searches. With the excellent resolution of the ATLAS and CMS detectors as a catalyst, one area that has undergone significant development is jet substructure physics. The use of jet substructure techniques, which probe the fine-grained details of how energy is distributed in jets, has two broad goals. First, measuring more than just the bulk properties of jets allows for additional probes of QCD. For example, jet substructure measurements can be compared against precision perturbative QCD calculations or used to tune Monte Carlo event generators. Second, jet substructure allows for additional handles in event discrimination. These handles could play an important role at the LHC in discriminating between signal and background events in a wide variety of particle searches. For example, Monte Carlo studies indicate that jet substructure techniques allow for efficient reconstruction of boosted heavy objects such as the W{sup {+-}} and Z{sup 0} gauge bosons, the top quark, and the Higgs boson.

  16. Jet quenching at ALICE

    International Nuclear Information System (INIS)

    Bianchi, Nicola

    2007-01-01

    RHIC results on leading hadron suppression indicate that the jets produced in hard processes are strongly quenched by the dense medium created in heavy ion collisions. Most of the energy lost by the leading parton remains within the jet cone, but several questions on the medium modification of the jet structure have not been addressed. These include the longitudinal and transverse structures of the quenched jet, the associated radiation observables, and the dependence on the parton flavor. These topics will be studied by ALICE thanks to both the robustness of its tracking and the charged particle identification system. Large medium effects are expected in both the low pt and in the high pt regions. To make ALICE better suited for jet physics, the performances on high p t particles and jets can be significantly improved by completing the present set-up with a large Electromagnetic Calorimeter (EmCal). This will significantly improve the resolution on the jet energy and on the particle composition (with the detection of both charged and neutral particles). It will also allow to calibrate the jet energy by measuring the high energy photon emitted in the opposite direction. EmCal will be used to trigger on the jet energy itself, thus allowing a significant improvement of the statistics achievable for jets of high energy. Finally, due too both the γ/π 0 and the electron/hadron discrimination, EmCal will enhance the ALICE capabilities at high p t for direct photons and heavy quarks measurements

  17. Biological correlates of extinction risk in bats.

    Science.gov (United States)

    Jones, Kate E; Purvis, Andy; Gittleman, John L

    2003-04-01

    We investigated patterns and processes of extinction and threat in bats using a multivariate phylogenetic comparative approach. Of nearly 1,000 species worldwide, 239 are considered threatened by the International Union for Conservation of Nature and Natural Resources (IUCN) and 12 are extinct. Small geographic ranges and low wing aspect ratios are independently found to predict extinction risk in bats, which explains 48% of the total variance in IUCN assessments of threat. The pattern and correlates of extinction risk in the two bat suborders are significantly different. A higher proportion (4%) of megachiropteran species have gone extinct in the last 500 years than microchiropteran bats (0.3%), and a higher proportion is currently at risk of extinction (Megachiroptera: 34%; Microchiroptera: 22%). While correlates of microchiropteran extinction risk are the same as in the order as a whole, megachiropteran extinction is correlated more with reproductive rate and less with wing morphology. Bat extinction risk is not randomly distributed phylogenetically: closely related species have more similar levels of threat than would be expected if extinction risk were random. Given the unbalanced nature of the evolutionary diversification of bats, it is probable that the amount of phylogenetic diversity lost if currently threatened taxa disappear may be greater than in other clades with numerically more threatened species.

  18. The ethics of reviving long extinct species.

    Science.gov (United States)

    Sandler, Ronald

    2014-04-01

    There now appears to be a plausible pathway for reviving species that have been extinct for several decades, centuries, or even millennia. I conducted an ethical analysis of de-extinction of long extinct species. I assessed several possible ethical considerations in favor of pursuing de-extinction: that it is a matter of justice; that it would reestablish lost value; that it would create new value; and that society needs it as a conservation last resort. I also assessed several possible ethical arguments against pursuing de-extinction: that it is unnatural; that it could cause animal suffering; that it could be ecologically problematic or detrimental to human health; and that it is hubristic. There are reasons in favor of reviving long extinct species, and it can be ethically acceptable to do so. However, the reasons in favor of pursuing de-extinction do not have to do with its usefulness in species conservation; rather, they concern the status of revived species as scientific and technological achievements, and it would be ethically problematic to promote de-extinction as a significant conservation strategy, because it does not prevent species extinctions, does not address the causes of extinction, and could be detrimental to some species conservation efforts. Moreover, humanity does not have a responsibility or obligation to pursue de-extinction of long extinct species, and reviving them does not address any urgent problem. Therefore, legitimate ecological, political, animal welfare, legal, or human health concerns associated with a de-extinction (and reintroduction) must be thoroughly addressed for it to be ethically acceptable. © 2013 Society for Conservation Biology.

  19. Jets in Planetary Atmospheres

    Science.gov (United States)

    Dowling, Tim

    2018-05-01

    Jet streams, "jets" for short, are remarkably coherent streams of air found in every major atmosphere. They have a profound effect on a planet's global circulation, and have been an enigma since the belts and zones of Jupiter were discovered in the 1600s. The study of jets, including what processes affect their size, strength, direction, shear stability, and predictability, are active areas of research in geophysical fluid dynamics. Jet research is multidisciplinary and global, involving collaborations between observers, experimentalists, numerical modelers, and applied mathematicians. Jets in atmospheres have strong analogies with shear instability in nonneutral plasmas, and these connections are highlighted throughout the article. The article begins with a description of four major challenges that jet researchers face: nonlinearity, non-intuitive wave physics, non-constant-coefficients, and copious nondimensional numbers. Then, two general fluid-dynamical tenets, the practice of rendering expressions dimensionally homogeneous (nondimensional), and the universal properties of shocks are applied to the open question of what controls the on-off switch of shear instability. The discussion progresses to how the physics of jets varies in equatorial, midlatitude, and polar regions, and how jets are observed to behave in each of these settings. The all-in-one conservation law of potential vorticity (PV), which combines the conservation laws of mass, momentum, and thermal energy into a single expression, is the common language of jet research. Earth and Uranus have weak retrograde equatorial jets, but most planets exhibit super-rotating equatorial jets, which require eddies to transport momentum up gradient in a non-intuitive manner. Jupiter and Saturn exhibit multiple alternating jets in their midlatitudes. The theory for why jets are invariably zonal (east-west orientated) is reviewed, and the particular challenges that Jupiter's sharp westward jets present to existing

  20. Nonword repetition in lexical decision: support for two opposing processes.

    Science.gov (United States)

    Wagenmakers, Eric-Jan; Zeelenberg, René; Steyvers, Mark; Shiffrin, Richard; Raaijmakers, Jeroen

    2004-10-01

    We tested and confirmed the hypothesis that the prior presentation of nonwords in lexical decision is the net result of two opposing processes: (1) a relatively fast inhibitory process based on global familiarity; and (2) a relatively slow facilitatory process based on the retrieval of specific episodic information. In three studies, we manipulated speed-stress to influence the balance between the two processes. Experiment 1 showed item-specific improvement for repeated nonwords in a standard "respond-when-ready" lexical decision task. Experiment 2 used a 400-ms deadline procedure and showed performance for nonwords to be unaffected by up to four prior presentations. In Experiment 3 we used a signal-to-respond procedure with variable time intervals and found negative repetition priming for repeated nonwords. These results can be accounted for by dual-process models of lexical decision.

  1. Neural Circuit to Integrate Opposing Motions in the Visual Field.

    Science.gov (United States)

    Mauss, Alex S; Pankova, Katarina; Arenz, Alexander; Nern, Aljoscha; Rubin, Gerald M; Borst, Alexander

    2015-07-16

    When navigating in their environment, animals use visual motion cues as feedback signals that are elicited by their own motion. Such signals are provided by wide-field neurons sampling motion directions at multiple image points as the animal maneuvers. Each one of these neurons responds selectively to a specific optic flow-field representing the spatial distribution of motion vectors on the retina. Here, we describe the discovery of a group of local, inhibitory interneurons in the fruit fly Drosophila key for filtering these cues. Using anatomy, molecular characterization, activity manipulation, and physiological recordings, we demonstrate that these interneurons convey direction-selective inhibition to wide-field neurons with opposite preferred direction and provide evidence for how their connectivity enables the computation required for integrating opposing motions. Our results indicate that, rather than sharpening directional selectivity per se, these circuit elements reduce noise by eliminating non-specific responses to complex visual information. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Islam, Islamophobia and the West: Opposing Views and Social Reality

    Directory of Open Access Journals (Sweden)

    Adila Pavelić

    2015-12-01

    Full Text Available Through reviewing different and often opposing views on the relationship between Islam and the West, the paper aims to offer a better understanding of this relationship, and of Islamophobia as an old, yet increasingly actual and in many respects relevant social problem. A short historical overview of the understanding of the relationship between Islam and the West, and various definitions of Islamophobia, are followed by examination of some recent works that from different perspectives deal with the issue. Firstly, is given insight into the works written by Western theorists who describe the relationship between Islam and the West within the framework of the idea of the clash of civilizations while, at the same time, labeling Islam often as a non-modern religion and culture whose members reject Western values such as democracy, freedom and gender equality. In contrast to them are introduced the authors whose argumentation opposes stereotypical views of Islam; among them are also those that critically address Islamophobia in today’s Western society, either by presenting results of their research on Islamophobia or by documenting the dominant media image of Islam, which has been perpetuating stereotypes, especially in the aftermath of the terrorist attacks on New York in 2001. Lastly, it is concluded that, regardless of the origin of works dealing with the relationship between Islam and the West or of the type of their arguments, they more often than not interpret Islam and the West primarily as two separate, self-contained and in itself incompatible worlds. In doing so, the authors here argue, they employ an essentialist and reductionist approach not only to Islam – as it might be assumed – but also to the West, while the relationship between Islam and the West is simplified and schematized.

  3. Strength training and testosterone treatment have opposing effects on migration inhibitor factor levels in ageing men

    DEFF Research Database (Denmark)

    Glintborg, D.; Christensen, L. L.; Kvorning, T.

    2013-01-01

    Strength Training and Testosterone Treatment Have Opposing Effects on Migration Inhibitor Factor Levels in Ageing Men......Strength Training and Testosterone Treatment Have Opposing Effects on Migration Inhibitor Factor Levels in Ageing Men...

  4. Phenomenology of jets

    International Nuclear Information System (INIS)

    Walsh, T.F.

    1980-05-01

    The basic idea of these lectures is very simple. Quarks and gluons - the elementary quanta of quantum chromodynamics or QCD - are produced with perturbarively calculable rates in short distance processes. This is because of asymptotic freedom. These quanta produced at short distances are, in a sense, 'visible' as jets of hadrons. (The jets do not contain the colored QCD quanta if - as we will assume - color is confined. The jets contain only colorless hadrons.) The distribution of these jets is the distribution of the original quanta, apart from fluctuations generated in the (long distance) jet formation process. The distribution of the jets can thus thest QCD in a particularly clear way at the parton level, at distance of order 5 x 10 -16 cm (PETRA/PEP energies). (orig.)

  5. A turbulent radio jet

    International Nuclear Information System (INIS)

    Kahn, F.D.

    1983-01-01

    A relativistic plasma flow can explain many of the observations on the one-sided jets, which are associated with radio sources that show superluminal motions in their cores. The pressure from the ambient medium will communicate across the jet in a relatively short distance, typically 30 kpc. The friction between the jet and the external medium then makes the flow go turbulent. As a result the jet dissipates energy and will be brought to rest within a few hundred kpc, if it does not strike an obstacle before. The mean flow in the jet is strongly sheared and stretches the lines of force of any magnetic field frozen into the plasma. The dominant field direction, as seen from the rest frame of the plasma, is therefore parallel to the length of the jet. Polarization measurements have shown that this is in fact the case. (author)

  6. Hadronic jets an introduction

    CERN Document Server

    Banfi, Andrea

    2016-01-01

    Jet physics is an incredibly rich subject detailing the narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a particle physics or heavy ion experiment. This book is a general overview of jet physics for scientists not directly involved in the field. It presents the basic experimental and theoretical problems arising when dealing with jets, and describing the solutions proposed in recent years.

  7. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.

    1988-03-01

    The paper is a JET progress report 1987, and covers the fourth full year of JET's operation. The report contains an overview summary of the scientific and technical advances during the year, and is supplemented by appendices of detailed contributions of the more important JET articles published during 1987. The document is aimed at specialists and experts engaged in nuclear fusion and plasma physics, as well as the general scientific community. (U.K.)

  8. Extinction debt: a challenge for biodiversity conservation.

    Science.gov (United States)

    Kuussaari, Mikko; Bommarco, Riccardo; Heikkinen, Risto K; Helm, Aveliina; Krauss, Jochen; Lindborg, Regina; Ockinger, Erik; Pärtel, Meelis; Pino, Joan; Rodà, Ferran; Stefanescu, Constantí; Teder, Tiit; Zobel, Martin; Steffan-Dewenter, Ingolf

    2009-10-01

    Local extinction of species can occur with a substantial delay following habitat loss or degradation. Accumulating evidence suggests that such extinction debts pose a significant but often unrecognized challenge for biodiversity conservation across a wide range of taxa and ecosystems. Species with long generation times and populations near their extinction threshold are most likely to have an extinction debt. However, as long as a species that is predicted to become extinct still persists, there is time for conservation measures such as habitat restoration and landscape management. Standardized long-term monitoring, more high-quality empirical studies on different taxa and ecosystems and further development of analytical methods will help to better quantify extinction debt and protect biodiversity.

  9. Temporal specificity of extinction in autoshaping.

    Science.gov (United States)

    Drew, Michael R; Yang, Cynthia; Ohyama, Tatsuya; Balsam, Peter D

    2004-07-01

    Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific. (c) 2004 APA, all rights reserved

  10. Open-field exposure facilitates consummatory extinction.

    Science.gov (United States)

    Justel, Nadia; Psyrdellis, Mariana; Pautassi, Ricardo M

    2016-12-07

    During extinction, the organism learns that a conditioned stimulus or a conditioned response is no longer associated with an unconditioned stimulus, and as a consequence, a decrement in the response is presented. The exposure to novel situations (e.g. exploration of a novel open field) has been used widely to modulate (i.e. either enhance or deteriorate) learning and memory. The aim of the present study was to test whether open-field exposure could modulate consummatory extinction. The results indicated that open-field exposure accelerated the extinction response (i.e. experimental animals provided novelty exposure had lower consummatory behavior than control animals) when applied before - but not after - the first extinction trial, or when applied before the second extinction trial. The results suggest that environmental treatments such as novelty exposure provide a valuable, nonpharmacological alternative to potentially modulate extinction processes.

  11. Light extinction in the atmosphere

    International Nuclear Information System (INIS)

    Laulainen, N.

    1992-06-01

    Atmospheric aerosol particles originating from natural sources, such as volcanos and sulfur-bearing gas emissions from the oceans, and from human sources, such as sulfur emissions from fossil fuel combustion and biomass burning, strongly affect visual air quality and are suspected to significantly affect radiative climate forcing of the planet. During the daytime, aerosols obscure scenic vistas, while at night they diminish our ability to observe stellar objects. Scattering of light is the main means by which aerosols attenuate and redistribute light in the atmosphere and by which aerosols can alter and reduce visibility and potentially modify the energy balance of the planet. Trends and seasonal variability of atmospheric aerosol loading, such as column-integrated light extinction or optical depth, and how they may affect potential climate change have been difficult to quantify because there have been few observations made of important aerosol optical parameters, such as optical depth, over the globe and over time and often these are of uneven quality. To address questions related to possible climate change, there is a pressing need to acquire more high-quality aerosol optical depth data. Extensive deployment of improved solar radiometers over the next few years will provide higher-quality extinction data over a wider variety of locations worldwide. An often overlooked source of turbidity data, however, is available from astronomical observations, particularly stellar photoelectric photometry observations. With the exception of the Project ASTRA articles published almost 20 years ago, few of these data ever appear in the published literature. This paper will review the current status of atmospheric extinction observations, as highlighted by the ASTRA work and augmented by more recent solar radiometry measurements

  12. Sexual selection protects against extinction.

    Science.gov (United States)

    Lumley, Alyson J; Michalczyk, Łukasz; Kitson, James J N; Spurgin, Lewis G; Morrison, Catriona A; Godwin, Joanne L; Dickinson, Matthew E; Martin, Oliver Y; Emerson, Brent C; Chapman, Tracey; Gage, Matthew J G

    2015-06-25

    Reproduction through sex carries substantial costs, mainly because only half of sexual adults produce offspring. It has been theorized that these costs could be countered if sex allows sexual selection to clear the universal fitness constraint of mutation load. Under sexual selection, competition between (usually) males and mate choice by (usually) females create important intraspecific filters for reproductive success, so that only a subset of males gains paternity. If reproductive success under sexual selection is dependent on individual condition, which is contingent to mutation load, then sexually selected filtering through 'genic capture' could offset the costs of sex because it provides genetic benefits to populations. Here we test this theory experimentally by comparing whether populations with histories of strong versus weak sexual selection purge mutation load and resist extinction differently. After evolving replicate populations of the flour beetle Tribolium castaneum for 6 to 7 years under conditions that differed solely in the strengths of sexual selection, we revealed mutation load using inbreeding. Lineages from populations that had previously experienced strong sexual selection were resilient to extinction and maintained fitness under inbreeding, with some families continuing to survive after 20 generations of sib × sib mating. By contrast, lineages derived from populations that experienced weak or non-existent sexual selection showed rapid fitness declines under inbreeding, and all were extinct after generation 10. Multiple mutations across the genome with individually small effects can be difficult to clear, yet sum to a significant fitness load; our findings reveal that sexual selection reduces this load, improving population viability in the face of genetic stress.

  13. The hydrogen laminar jet

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Sanz, M. [Departamento de Motopropulsion y Termofluidomecanica, ETSI Aeronauticos, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Rosales, M. [Department Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, 28911, Leganes (Spain); Instituto de Innovacion en Mineria y Metalurgia, Avenida del Valle 738, Santiago (Chile); Sanchez, A.L. [Department Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, 28911, Leganes (Spain)

    2010-04-15

    Numerical and asymptotic methods are used to investigate the structure of the hydrogen jet discharging into a quiescent air atmosphere. The analysis accounts in particular for the variation of the density and transport properties with composition. The Reynolds number of the flow R{sub j}, based on the initial jet radius a, the density {rho}{sub j} and viscosity {mu}{sub j} of the jet and the characteristic jet velocity u{sub j}, is assumed to take moderately large values, so that the jet remains slender and stable, and can be correspondingly described by numerical integration of the continuity, momentum and species conservation equations written in the boundary-layer approximation. The solution for the velocity and composition in the jet development region of planar and round jets, corresponding to streamwise distances of order R{sub j}a, is computed numerically, along with the solutions that emerge both in the near field and in the far field. The small value of the hydrogen-to-air molecular weight ratio is used to simplify the solution by considering the asymptotic limit of vanishing jet density. The development provides at leading-order explicit analytical expressions for the far-field velocity and hydrogen mass fraction that describe accurately the hydrogen jet near the axis. The information provided can be useful in particular to characterize hydrogen discharge processes from holes and cracks. (author)

  14. Properties of gluon jets

    International Nuclear Information System (INIS)

    Sugano, K.

    1987-01-01

    The properties of gluon jets are reviewed, and the measured characteristics are compared to the theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, in general the agreement between experiment and theory is remarkable. There are some intriguing differences. Since the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed

  15. Properties of gluon jets

    International Nuclear Information System (INIS)

    Sugano, K.

    1988-01-01

    The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on understanding of QCD. The future prospects are discussed

  16. Are jets really there

    International Nuclear Information System (INIS)

    Lillethun, E.

    1976-09-01

    Based on the results of high energy proton-proton collisions obtained at the CERN ISR in 1972-73, the production of 'jets' is discussed. Jets in e + e - collisions are also discussed and the parameters 'sphericity' and 'rapidity' are used in analysis of the data. The jets studied have been defined as having at least one particle of high transverse momentum. It is not clear whether the jets represent new physics or are another way of stating that resonances (rho,K*, Δ, N* etc.) are produced with high p(sub T), and that in such production the high transverse momentum must be balanced essentially locally in the collision. (JIW)

  17. Comment on the extinct paradox

    International Nuclear Information System (INIS)

    Levine, D.M.

    1983-11-01

    The extinction paradox is a contradiction between geometrical optics results which predict that at high frequencies the scattering cross section of an object should equal its geometrical cross section and rigorous scattering theory which shows that at high frequencies the scattering cross section approaches twice the geometrical cross section of the object. Confusion about the reason for this paradox persists today even though the nature of the paradox was correctly identified many years ago by Brillouin. The resolution of the paradox is restated and illustrated with an example, and then the implications to the interpretation of scattering cross sections are identified

  18. Presidential address: distinction or extinction.

    Science.gov (United States)

    Pressman, Barry D

    2008-10-01

    Despite its continuing scientific successes in imaging, radiology as a specialty is faced with a very difficult and competitive environment. Nonradiologists are more and more interested in vertically integrating imaging into their practices, while teleradiology and picture archiving and communication systems are resulting in the greater isolation of radiologists. Commoditization is a realistic and devastating threat to the survival and professionalism of the specialty. To remain viable as a specialty, radiologists must elevate their practice by subspecializing, becoming more involved with clinical care, and actively interacting with patients and referring clinicians. Distinction will prevent extinction.

  19. Methylphenidate enhances extinction of contextual fear

    OpenAIRE

    Abraham, Antony D.; Cunningham, Christopher L.; Lattal, K. Matthew

    2012-01-01

    Methylphenidate (MPH, Ritalin) is a norepinephrine and dopamine transporter blocker that is widely used in humans for treatment of attention deficit disorder and narcolepsy. Although there is some evidence that targeted microinjections of MPH may enhance fear acquisition, little is known about the effect of MPH on fear extinction. Here, we show that MPH, administered before or immediately following extinction of contextual fear, will enhance extinction retention in C57BL/6 mice. Animals that ...

  20. Are Humans too Numerous to Become Extinct?

    OpenAIRE

    Cairns, John

    2009-01-01

    Some claim that humans are too numerous to become extinct. However, passenger pigeon, once the most numerous birds on the planet, are now extinct. For years, humankind has been damaging its habitat, discharging toxic chemicals into the environment, and having harmful effects on agricultural productivity due to climate change. Humankind s extinction depends on the continuation of various human activities including economic growth, addiction to fossil fuel, over consumption, overpopulation, oc...

  1. The Astronomical Pulse of Global Extinction Events

    Directory of Open Access Journals (Sweden)

    David F.V. Lewis

    2006-01-01

    Full Text Available The linkage between astronomical cycles and the periodicity of mass extinctions is reviewed and discussed. In particular, the apparent 26 million year cycle of global extinctions may be related to the motion of the solar system around the galaxy, especially perpendicular to the galactic plane. The potential relevance of Milankovitch cycles is also explored in the light of current evidence for the possible causes of extinction events over a geological timescale.

  2. Experimental study of hydrogen jet ignition and jet extinguishment

    International Nuclear Information System (INIS)

    Wierman, R.W.

    1979-04-01

    Two phases are described of an experimental study that investigated: (1) the ignition characteristics of hydrogen--sodium jets, (2) the formation of hydrogen in sodium--humid air atmospheres, and (3) the extinguishment characteristics of burning hydrogen--sodium jets. Test conditions were similar to those postulated for highly-improbable breeder reactor core melt-through accidents and included: jet temperature, jet velocity, jet hydrogen concentration, jet sodium concentration, atmospheric oxygen concentration, and atmospheric water vapor concentration

  3. Long-term maintenance of immediate or delayed extinction is determined by the extinction-test interval

    OpenAIRE

    Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

    2010-01-01

    Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively long extinction-test interval was used; a relatively short extinction-test interval yielded the opposite result (Experiment 2). Previous data appear co...

  4. Intergalactic extinction and the deceleration parameter

    International Nuclear Information System (INIS)

    Meinel, R.

    1981-01-01

    The deceleration parameter q 0 is calculated from the relation between apparent magnitudes m of the brightest galaxies in clusters and their redshifts z considering an intergalactic extinction. The calculation is valid for a Friedman universe, homogeneously filled with dust grains, assuming the extinction to be 0.5 mag at z = 1 and aΛ -1 -law of extinction (according to Oleak and Schmidt 1976). Using the m,z-values of Kristian, Sandage, and Westphal (1978) a formal value of q 0 approximately 2.1 is obtained instead of q 0 approximately 1.6 without consideration of intergalactic extinction. (author)

  5. Interstellar extinction in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

    1980-01-01

    Recent UV observations together with complementary visible data of several reddened and comparison stars of similar spectral types in the Large Magellanic Cloud have been used to study the interstellar extinction in that galaxy. Most of the reddened stars studied here are located within 2 0 of 30 Doradus and show remarkably high extinction in the far UV, suggesting a large abundance of small particles. From the optical wavelength to 2,600 A the normalised extinction curves of the LMC stars are similar to the mean galactic extinction law. (author)

  6. Mass extinctions vs. uniformitarianism in biological evolution

    Energy Technology Data Exchange (ETDEWEB)

    Bak, P.; Paczuski, M.

    1995-12-31

    It is usually believed that Darwin`s theory leads to a smooth gradual evolution, so that mass extinctions must be caused by external shocks. However, it has recently been argued that mass extinctions arise from the intrinsic dynamics of Darwinian evolution. Species become extinct when swept by intermittent avalanches propagating through the global ecology. These ideas are made concrete through studies of simple mathematical models of co-evolving species. The models exhibit self-organized criticality and describe some general features of the extinction pattern in the fossil record.

  7. Jet mass spectra in Higgs+one jet at NNLL

    International Nuclear Information System (INIS)

    Jouttenus, Teppo T.; Stewart, Iain W.; Waalewijn, Wouter J.

    2013-02-01

    The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m 2 jet /p jet T scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

  8. Jet mass spectra in Higgs+one jet at NNLL

    Energy Technology Data Exchange (ETDEWEB)

    Jouttenus, Teppo T.; Stewart, Iain W. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Waalewijn, Wouter J. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    2013-02-15

    The invariant mass of a jet is a benchmark variable describing the structure of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a factorization formula. At this order, the cross section becomes sensitive to perturbation theory at the soft m{sup 2}{sub jet}/p{sup jet}{sub T} scale. Our calculation is exclusive and uses the 1-jettiness global event shape to implement a veto on additional jets. The dominant dependence on the jet veto is removed by normalizing the spectrum, leaving residual dependence from non-global logarithms depending on the ratio of the jet mass and jet veto variables. For our exclusive jet cross section these non-global logarithms are parametrically smaller than in the inclusive case, allowing us to obtain a complete NNLL result. Results for the dependence of the jet mass spectrum on the kinematics, jet algorithm, and jet size R are given. Using individual partonic channels we illustrate the difference between the jet mass spectra for quark and gluon jets. We also study the effect of hadronization and underlying event on the jet mass in Pythia. To highlight the similarity of inclusive and exclusive jet mass spectra, a comparison to LHC data is presented.

  9. Investigation of PVdF active diaphragms for synthetic jets

    Science.gov (United States)

    Bailo, Kelly C.; Brei, Diann E.; Calkins, Frederick T.

    2000-06-01

    Current research has shown that aircraft can gain significant aerodynamic performance benefits by employing active flow control (AFC). One of the enabling technologies of AFC is the synthetic jet. Synthetic jets, also known as zero-net-mass flux actuators, act as bi-directional pumps injecting high momentum air into the local aerodynamic flow. Previous work has concentrated on high frequency synthetic jets based on piezoelectric active diaphragms such as Thunder actuators. Low frequency synthetic jets present a unique challenge requiring large displacements, which current technology has difficulty meeting. Boeing is investigating novel shaped low frequency synthetic jets that can modify the flow over fixed aircraft wings. This paper present the initial study of two promising active diaphragm concepts: a crescent shape and an opposing bender shape. These active diaphragms were numerically modeled utilizing the general-purpose finite element code ABAQUS. Using the ABAQUS results, the dynamic volume change within each jet was calculated and incorporated into an analytical linear Bernoulli model to predict the velocities and pressures at the nozzle. Simulations were performed to determine trends to assist in selection of prototype configurations. Prototypes of both diaphragm concepts were constructed from polyvinylidene fluoride and experimentally tested at Boeing with promising results.

  10. Jet physics in ALICE

    International Nuclear Information System (INIS)

    Loizides, C.A.

    2005-01-01

    The ALICE experiment is one of the experiments currently prepared for the Large Hadron Collider (LHC) at CERN, Geneva, starting operation end of 2007. ALICE is dedicated to the research on nucleus-nucleus collisions at ultra-relativistic energies, which addresses the properties of strongly interacting matter under varying conditions of high density and temperature. The conditions provided at the LHC allow significant qualitative improvement with respect to previous studies. In particular, energetic probes, light quarks and gluons, will be abundantly produced. These probes might be identified by their fragmentation into correlated particles, so called jets, of high enough energy to allow full reconstruction of jet properties; even in the underlying heavy-ion environment. Understanding the dependence of high-energy jet production and fragmentation influenced by the dense medium created in the collision region is an open field of active research. Generally, one expects energy loss of the probes due to medium-induced gluon radiation. It is suggested that hadronization products of these, rather soft gluons may be contained within the jet emission cone, resulting in a modification of the characteristic jet fragmentation, as observed via longitudinal and transverse momentum distributions with respect to the direction of the initial parton, as well as of the multiplicity distributions arising from the jet fragmentation. Particle momenta parallel to the jet axis are softened (jet quenching), while transverse to it increased (transverse heating). The present thesis studies the capabilities of the ALICE detectors to measure these jets and quantifies obtainable rates and the quality of jet reconstruction, in both proton-proton and lead-lead collisions at the LHC. In particular, it is addressed whether modification of the jet fragmentation can be detected within the high-particle-multiplicity environment of central lead-lead collisions. (orig.)

  11. Deformations of free jets

    Science.gov (United States)

    Paruchuri, Srinivas

    This thesis studies three different problems. First we demonstrate that a flowing liquid jet can be controllably split into two separate subfilaments through the applications of a sufficiently strong tangential stress to the surface of the jet. In contrast, normal stresses can never split a liquid jet. We apply these results to observations of uncontrolled splitting of jets in electric fields. The experimental realization of controllable jet splitting would provide an entirely novel route for producing small polymeric fibers. In the second chapter we present an analytical model for the bending of liquid jets and sheets from temperature gradients, as recently observed by Chwalek et al. [Phys. Fluids, 14, L37 (2002)]. The bending arises from a local couple caused by Marangoni forces. The dependence of the bending angle on experimental parameters is presented, in qualitative agreement with reported experiments. The methodology gives a simple framework for understanding the mechanisms for jet and sheet bending. In chapter 4 we address the discrepancy between hydrodynamic theory of liquid jets, and the snap-off of narrow liquid jets observed in molecular dynamics (MD) simulations [23]. This has been previously attributed to the significant role of thermal fluctuations in nanofluidic systems. We argue that hydrodynamic description of such systems should include corrections to the Laplace pressure which result from the failure of the sharp interface assumption when the jet diameter becomes small enough. We show that this effect can in principle give rise to jet shapes similar to those observed in MD simulations, even when thermal fluctuations are completely neglected. Finally we summarize an algorithm developed to simulate droplet impact on a smooth surface.

  12. Anatomical physiology of spatial extinction.

    Science.gov (United States)

    Ciçek, Metehan; Gitelman, Darren; Hurley, Robert S E; Nobre, Anna; Mesulam, Marsel

    2007-12-01

    Neurologically intact volunteers participated in a functional magnetic resonance imaging experiment that simulated the unilateral (focal) and bilateral (global) stimulations used to elicit extinction in patients with hemispatial neglect. In peristriate areas, attentional modulations were selectively sensitive to contralaterally directed attention. A higher level of mapping was observed in the intraparietal sulcus (IPS), inferior parietal lobule (IPL), and inferior frontal gyrus (IFG). In these areas, there was no distinction between contralateral and ipsilateral focal attention, and the need to distribute attention globally led to greater activity than either focal condition. These physiological characteristics were symmetrically distributed in the IPS and IFG, suggesting that the effects of unilateral lesions in these 2 areas can be compensated by the contralateral hemisphere. In the IPL, the greater activation by the bilateral attentional mode was seen only in the right hemisphere. Its contralateral counterpart displayed equivalent activations when attention was distributed to the right, to the left, or bilaterally. Within the context of this experiment, the IPL of the right hemisphere emerged as the one area where unilateral lesions can cause the most uncompensated and selective impairment of global attention (without interfering with unilateral attention to either side), giving rise to the phenomenon of extinction.

  13. Constraints on Enhanced Extinction Resulting from Extinction Treatment in the Presence of an Added Excitor

    Science.gov (United States)

    Urcelay, Gonzalo P.; Lipatova, Olga; Miller, Ralph R.

    2009-01-01

    Three Pavlovian fear conditioning experiments with rats as subjects explored the effect of extinction in the presence of a concurrent excitor. Our aim was to explore this particular treatment, documented in previous studies to deepen extinction, with novel control groups to shed light on the processes involved in extinction. Relative to subjects…

  14. Timing of extinction relative to acquisition: A parametric analysis of fear extinction in humans

    NARCIS (Netherlands)

    Norrholm, S.D.; Vervliet, B.; Jovanovic, T.; Boshoven, W.; Myers, K.M.; Davis, M.; Rothbaum, B.O.; Duncan, E.J.

    2008-01-01

    Fear extinction is a reduction in conditioned fear following repeated exposure to the feared cue in the absence of any aversive event. Extinguished fear often reappears after extinction through spontaneous recovery. Animal studies suggest that spontaneous recovery can be abolished if extinction

  15. Targeting extinction and reconsolidation mechanisms to combat the impact of drug cues on addiction.

    Science.gov (United States)

    Taylor, Jane R; Olausson, Peter; Quinn, Jennifer J; Torregrossa, Mary M

    2009-01-01

    Drug addiction is a progressive and compulsive disorder, where recurrent craving and relapse to drug-seeking occur even after long periods of abstinence. A major contributing factor to relapse is drug-associated cues. Here we review behavioral and pharmacological studies outlining novel methods of effective and persistent reductions in cue-induced relapse behavior in animal models. We focus on extinction and reconsolidation of cue-drug associations as the memory processes that are the most likely targets for interventions. Extinction involves the formation of new inhibitory memories rather than memory erasure; thus, it should be possible to facilitate the extinction of cue-drug memories to reduce relapse. We propose that context-dependency of extinction might be altered by mnemonic agents, thereby enhancing the efficacy of cue-exposure therapy as treatment strategy. In contrast, interfering with memory reconsolidation processes can disrupt the integrity or strength of specific cue-drug memories. Reconsolidation is argued to be a distinct process that occurs over a brief time period after memory is reactivated/retrieved - when the memory becomes labile and vulnerable to disruption. Reconsolidation is thought to be an independent, perhaps opposing, process to extinction and disruption of reconsolidation has recently been shown to directly affect subsequent cue-drug memory retrieval in an animal model of relapse. We hypothesize that a combined approach aimed at both enhancing the consolidation of cue-drug extinction and interfering with the reconsolidation of cue-drug memories will have a greater potential for persistently inhibiting cue-induced relapse than either treatment alone.

  16. Quark jets, gluon jets and the three-gluon vertex

    International Nuclear Information System (INIS)

    Fodor, Z.

    1989-11-01

    Using hadronic jets in electron-positron annihilation, we suggest a simple and model-independent method to see the differences between quark and gluon jets. We define and analyse special energy dependent moments of jets and choose those which are the most characteristic to the jet type. The method handles the energy of a jet in an adequate way. We discuss new methods using jet flavor tagging, ordinary flavor tagging of a definite quark jet or discrimination between quark and gluon jets, to test the triple-gluon vertex in electron-positron annihilation. An enriched sample of gluon jets, jets with the smallest energy in four-jet events, as well as a continuous tagging variable are also studied. 21 refs., 6 figs. (Author)

  17. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.

    1987-03-01

    The paper presents the progress report of the Joint European Torus (JET) Joint Undertaking, 1986. The report contains a survey of the scientific and technical achievements on JET during 1986; the more important articles referred to in this survey are reproduced as appendices to this Report. The last section discusses developments which might improve the overall performance of the machine. (U.K.)

  18. Natural ventilation of buildings: opposing wind and buoyancy

    Science.gov (United States)

    Linden, Paul; Hunt, Gary

    1998-11-01

    The use of natural ventilation in buildings is an attractive way to reduce energy usage thereby reducing costs and CO2 emissions. Generally, it is necessary to remove excess heat from a building and the designer can use the buoyancy forces associated with the above ambient temperatures within the building to drive a flow - 'stack' ventilation. The most efficient mode is displacement ventilation where warm air accumulates near the top of the building and flows out through upper level vents and cooler air flows in at lower levels. Ventilation will also be driven between these lower and upper openings by the wind. We report on laboratory modeling and theory which investigates the effects of an opposing wind on stack ventilation driven by a constant source of heat within a space under displacement ventilation. We show that there is a critical wind speed, expressed in dimensionless terms as a critical Froude number, above which displacement ventilation is replaced by (less efficient) mixing ventilation with reversed flow. Below this critical speed, displacement ventilation, in which the interior has a two-layer stratification, is maintained. The criterion for the change in ventilation mode is derived from general considerations of mixing efficiencies in stratified flows. We conclude that even when wind effects might appear to be dominant, the inhibition of mixing by the stable stratification within the space ensures that stack ventilation can operate over a wide range of apparently adverse conditions.

  19. Opposing effects of humidity on rhodochrosite surface oxidation.

    Science.gov (United States)

    Na, Chongzheng; Tang, Yuanzhi; Wang, Haitao; Martin, Scot T

    2015-03-03

    Rhodochrosite (MnCO3) is a model mineral representing carbonate aerosol particles containing redox-active elements that can influence particle surface reconstruction in humid air, thereby affecting the heterogeneous transformation of important atmospheric constituents such as nitric oxides, sulfur dioxides, and organic acids. Using in situ atomic force microscopy, we show that the surface reconstruction of rhodochrosite in humid oxygen leads to the formation and growth of oxide nanostructures. The oxidative reconstruction consists of two consecutive processes with distinctive time scales, including a long waiting period corresponding to slow nucleation and a rapid expansion phase corresponding to fast growth. By varying the relative humidity from 55 to 78%, we further show that increasing humidity has opposing effects on the two processes, accelerating nucleation from 2.8(±0.2) × 10(-3) to 3.0(±0.2) × 10(-2) h(-1) but decelerating growth from 7.5(±0.3) × 10(-3) to 3.1(±0.1) × 10(-3) μm(2) h(-1). Through quantitative analysis, we propose that nanostructure nucleation is controlled by rhodochrosite surface dissolution, similar to the dissolution-precipitation mechanism proposed for carbonate mineral surface reconstruction in aqueous solution. To explain nanostructure growth in humid oxygen, a new Cabrera-Mott mechanism involving electron tunneling and solid-state diffusion is proposed.

  20. Bidirectional transport of organelles: unity and struggle of opposing motors.

    Science.gov (United States)

    Bryantseva, Sofiya A; Zhapparova, Olga N

    2012-01-01

    Bidirectional transport along microtubules is ensured by opposing motor proteins: cytoplasmic dynein that drives cargo to the minus-ends and various kinesins that generally move to the plus-ends of microtubules. Regulation of motor proteins that are simultaneously bound to the same organelle is required to maintain directional transport and prevent pausing of cargo pulled away by motors of opposite polarity. Debates of the recent decade have been focused on two possible mechanisms of such regulation: (i) coordination, which implies that only one type of motors is active at a given time, and (ii) tug-of-war, which assumes that both motors are active at the same time and that direction of transport depends on the outcome of motor's confrontation. The initial idea of coordination has been challenged by observations of simultaneous activity of plus- and minus-end-directed motors applied to the same cargo. Analysis of the available data indicates that coordination and tug-of-war theories rather complement than contradict each other: cargo interacts with two teams of active motors, the resulting direction and the winner team are determined by coordination complexes, but the activity of the loser team is never completely inhibited and remains at some background level. Such persisting activity might enhance the overall efficiency of transport by increasing processivity or helping to overcome the obstacles on microtubule track. © The Author(s) Journal compilation © 2012 Portland Press Limited

  1. Jet physics at CDF

    International Nuclear Information System (INIS)

    Melese, P.

    1997-05-01

    We present high E T jet measurements from CDF at the Fermilab Tevatron Collider. The incfilusive jet cross section at √s = 1800 GeV with ∼ 5 times more data is compared to the published CDF results, preliminary D0 results, and next-to-leading order QCD predictions. The summation E T cross section is also compared to QCD predictions and the dijet angular distribution is used to place a limit on quark compositeness. The inclusive jet cross section at √s = 630 GeV is compared with that at 1800 GeV to test the QCD predictions for the scaling of jet cross sections with √s. Finally, we present momentum distributions of charged particles in jets and compare them to Modified Leading Log Approximation predictions

  2. Jet physics in ATLAS

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Measurements of hadronic jets provide tests of strong interactions which are interesting both in their own right and as backgrounds to many New Physics searches. It is also through tests of Quantum Chromodynamics that new physics may be discovered. The extensive dataset recorded with the ATLAS detector throughout the 7 TeV centre-of-mass LHC operation period allows QCD to be probed at distances never reached before. We present a review of selected ATLAS jet performance and physics measurements, together with results from new physics searches using the 2011 dataset. They include studies of the underlying event and fragmentation models, measurements of the inclusive jet, dijet and multijet cross sections, parton density functions, heavy flavours, jet shape, mass and substructure. Searches for new physics in monojet, dijet and photon-jet final states are also presented.

  3. Long-Term Maintenance of Immediate or Delayed Extinction Is Determined by the Extinction-Test Interval

    Science.gov (United States)

    Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

    2010-01-01

    Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively…

  4. The role of the medial prefrontal cortex in the conditioning and extinction of fear

    Directory of Open Access Journals (Sweden)

    Thomas Francis Giustino

    2015-11-01

    Full Text Available Once acquired, a fearful memory can persist for a lifetime. Although learned fear can be extinguished, extinction memories are fragile. The resilience of fear memories to extinction may contribute to the maintenance of disorders of fear and anxiety, including post-traumatic stress disorder (PTSD. As such, considerable effort has been placed on understanding the neural circuitry underlying the acquisition, expression, and extinction of emotional memories in rodent models as well as in humans. A triad of brain regions, including the prefrontal cortex, hippocampus, and amygdala, form an essential brain circuit involved in fear conditioning and extinction. Within this circuit, the prefrontal cortex is thought to exert top-down control over subcortical structures to regulate appropriate behavioral responses. Importantly, a division of labor has been proposed in which the prelimbic (PL and infralimbic (IL subdivisions of the medial prefrontal cortex (mPFC regulate the expression and suppression of fear in rodents, respectively. Here we critically review the anatomical and physiological evidence that has led to this proposed dichotomy of function within mPFC. We propose that under some conditions, the PL and IL act in concert, exhibiting similar patterns of neural activity in response to aversive conditioned stimuli and during the expression or inhibition of conditioned fear. This may stem from common synaptic inputs, parallel downstream outputs, or cortico-cortical interactions. Despite this functional covariation, these mPFC subdivisions may still be coding for largely opposing behavioral outcomes, with PL biased towards fear expression and IL towards suppression.

  5. Affective-associative two-process theory: a neurocomputational account of partial reinforcement extinction effects.

    Science.gov (United States)

    Lowe, Robert; Almér, Alexander; Billing, Erik; Sandamirskaya, Yulia; Balkenius, Christian

    2017-12-01

    The partial reinforcement extinction effect (PREE) is an experimentally established phenomenon: behavioural response to a given stimulus is more persistent when previously inconsistently rewarded than when consistently rewarded. This phenomenon is, however, controversial in animal/human learning theory. Contradictory findings exist regarding when the PREE occurs. One body of research has found a within-subjects PREE, while another has found a within-subjects reversed PREE (RPREE). These opposing findings constitute what is considered the most important problem of PREE for theoreticians to explain. Here, we provide a neurocomputational account of the PREE, which helps to reconcile these seemingly contradictory findings of within-subjects experimental conditions. The performance of our model demonstrates how omission expectancy, learned according to low probability reward, comes to control response choice following discontinuation of reward presentation (extinction). We find that a PREE will occur when multiple responses become controlled by omission expectation in extinction, but not when only one omission-mediated response is available. Our model exploits the affective states of reward acquisition and reward omission expectancy in order to differentially classify stimuli and differentially mediate response choice. We demonstrate that stimulus-response (retrospective) and stimulus-expectation-response (prospective) routes are required to provide a necessary and sufficient explanation of the PREE versus RPREE data and that Omission representation is key for explaining the nonlinear nature of extinction data.

  6. Can Parallelingualism Save Norwegian from Extinction?

    Science.gov (United States)

    Linn, Andrew R.

    2010-01-01

    Language extinction is one of the most pressing issues in linguistics today, and the literature is full of discussion about how to combat it. Statements that Norwegian is amongst the languages that are already extinct are merely examples of a widespread tendency in the literature towards erroneous information about Norwegian. Nonetheless, there is…

  7. Evaluating herbivore extinction probabilities in Addo Elephant ...

    African Journals Online (AJOL)

    Abstract. Population extinction evaluations, based on the model developed by Dennis et al. (1991) that did not take density dependence into account and that were based on census data, suggest that many of the herbivore species in Addo Elephant National Park (AENP) are vulnerable to local extinction. As a result of low ...

  8. Extinction-Induced Variability in Human Behavior

    Science.gov (United States)

    Kinloch, Jennifer M.; Foster, T. Mary; McEwan, James S. A.

    2009-01-01

    Participants earned points by pressing a computer space bar (Experiment 1) or forming rectangles on the screen with the mouse (Experiment 2) under differential-reinforcement-of-low-rate schedules, followed by extinction. Variability in interresponse time (the contingent dimension) increased during extinction, as for Morgan and Lee (1996);…

  9. Context and Behavioral Processes in Extinction

    Science.gov (United States)

    Bouton, Mark E.

    2004-01-01

    This article provides a selective review and integration of the behavioral literature on Pavlovian extinction. The first part reviews evidence that extinction does not destroy the original learning, but instead generates new learning that is especially context-dependent. The second part examines insights provided by research on several related…

  10. Current extinction rates of reptiles and amphibians.

    Science.gov (United States)

    Alroy, John

    2015-10-20

    There is broad concern that a mass extinction of amphibians and reptiles is now underway. Here I apply an extremely conservative Bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. The data stem from a combination of museum collection databases and published site surveys. The method computes an extinction probability for each species by considering its sighting frequency and last sighting date. It infers hardly any extinction when collection dates are randomized and it provides underestimates when artificial extinction events are imposed. The method also appears to be insensitive to trends in sampling; therefore, the counts it provides are absolute minimums. Extinctions or severe population crashes have accumulated steadily since the 1970s and 1980s, and at least 3.1% of frog species have already disappeared. Based on these data and this conservative method, the best estimate of the global grand total is roughly 200 extinctions. Consistent with previous results, frog losses are heavy in Latin America, which has been greatly affected by the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Extinction rates are now four orders-of-magnitude higher than background, and at least another 6.9% of all frog species may be lost within the next century, even if there is no acceleration in the growth of environmental threats.

  11. Lidar extinction measurement in the mid infrared

    Science.gov (United States)

    Mitev, Valentin; Babichenko, S.; Borelli, R.; Fiorani, L.; Grigorov, I.; Nuvoli, M.; Palucci, A.; Pistilli, M.; Puiu, Ad.; Rebane, Ott; Santoro, S.

    2014-11-01

    We present a lidar measurement of atmospheric extinction coefficient. The measurement is performed by inversion of the backscatter lidar signal at wavelengths 3'000nm and 3'500nm. The inversion of the backscatter lidar signal was performed with constant extinction-to-backscatter ration values of 104 and exponential factor 0.1.

  12. Interstellar extinction in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.

    1981-01-01

    A systematic investigation of interstellar extinction in the ultraviolet as a function of position in the Large Magellanic Cloud has been made from an enlarged sample of reddened and comparison stars distributed throughout the cloud. Except for one star SK-69-108, the most reddened star of our sample, the shape of the extinction curves for the LMC stars do not show significant variations. All curves show an increase in extinction towards 2200 A, but some have maxima near 2200 A, some near 1900 A. It has been shown that the feature of the extinction curve near 1900 A is caused by the mismatch of the stellar F III 1920 A feature. The strength of this 1920 A feature as a function of luminosity and spectral type has been determined. The extinction curves have been corrected for the mismatch of the 1920 feature and a single mean extinction curve for the LMC normalized to Asub(V) = 0 and Esub(B-V) = 1 is presented. For the same value of Esub(B-V) the LMC stars show the 2200 A feature weaker by a factor 2 as compared with the galactic stars. Higher extinction shortward of 2000 A in the LMC extinction curves than that in our Galaxy, as reported in earlier papers, is confirmed. (author)

  13. Enhancing Divergent Search through Extinction Events

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    for the capacity to evolve. This hypothesis is tested through experiments in two evolutionary robotics domains. The results show that combining extinction events with divergent search increases evolvability, while combining them with convergent search offers no similar benefit. The conclusion is that extinction...

  14. Mass extinctions: Ecological selectivity and primary production

    Science.gov (United States)

    Rhodes, Melissa Clark; Thayer, Charles W.

    1991-09-01

    If mass extinctions were caused by reduced primary productivity, then extinctions should be concentrated among animals with starvation-susceptible feeding modes, active lifestyles, and high-energy budgets. The stratigraphic ranges (by stage) of 424 genera of bivalves and 309 genera of articulate brachiopods suggest that there was an unusual reduction of primary productivity at the Cretaceous/Tertiary (K/T) boundary extinction. For bivalves at the K/T, there were (1) selective extinction of suspension feeders and other susceptible trophic categories relative to deposit feeders and other resistant categories, and (2) among suspension feed-ers, selective extinction of bivalves with active locomotion. During the Permian-Triassic (P/Tr) extinction and Jurassic background time, extinction rates among suspension feeders were greater for articulate brachiopods than for bivalves. But during the K/T event, extinction rates of articulates and suspension-feeding bivalves equalized, possibly because the low-energy budgets of articulates gave them an advantage when food was scarce.

  15. Defining the period of moa extinction

    International Nuclear Information System (INIS)

    Anderson, A.

    2000-01-01

    Few aspects of New Zealand's prehistory have engaged scientific and public attention so consistently as two interlinked questions of moa extinction; when did moas become extinct and why? Answers offered over the last 160 years have run the gamut from chronological antiquity by evolutionary senescence, to within the 19th century Maori and European disturbance. (author)

  16. Immediate extinction promotes the return of fear.

    Science.gov (United States)

    Merz, Christian J; Hamacher-Dang, Tanja C; Wolf, Oliver T

    2016-05-01

    Accumulating evidence indicates that immediate extinction is less effective than delayed extinction in attenuating the return of fear. This line of fear conditioning research impacts the proposed onset of psychological interventions after threatening situations. In the present study, forty healthy men were investigated in a differential fear conditioning paradigm with fear acquisition in context A, extinction in context B, followed by retrieval testing in both contexts 24h later to test fear renewal. Differently coloured lights served as conditioned stimuli (CS): two CS (CS+) were paired with an electrical stimulation that served as unconditioned stimulus, the third CS was never paired (CS-). Extinction took place immediately after fear acquisition or 24h later. One CS+ was extinguished whereas the second CS+ remained unextinguished to control for different time intervals between fear acquisition and retrieval testing. Immediate extinction led to larger skin conductance responses during fear retrieval to both the extinguished and unextinguished CS relative to the CS-, indicating a stronger return of fear compared to delayed extinction. Taken together, immediate extinction is less potent than delayed extinction and is associated with a stronger renewal effect. Thus, the time-point of psychological interventions relative to the offset of threatening situations needs to be carefully considered to prevent relapses. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Mass extinction in poorly known taxa.

    Science.gov (United States)

    Régnier, Claire; Achaz, Guillaume; Lambert, Amaury; Cowie, Robert H; Bouchet, Philippe; Fontaine, Benoît

    2015-06-23

    Since the 1980s, many have suggested we are in the midst of a massive extinction crisis, yet only 799 (0.04%) of the 1.9 million known recent species are recorded as extinct, questioning the reality of the crisis. This low figure is due to the fact that the status of very few invertebrates, which represent the bulk of biodiversity, have been evaluated. Here we show, based on extrapolation from a random sample of land snail species via two independent approaches, that we may already have lost 7% (130,000 extinctions) of the species on Earth. However, this loss is masked by the emphasis on terrestrial vertebrates, the target of most conservation actions. Projections of species extinction rates are controversial because invertebrates are essentially excluded from these scenarios. Invertebrates can and must be assessed if we are to obtain a more realistic picture of the sixth extinction crisis.

  18. Assessing Extinction Risk: Integrating Genetic Information

    Directory of Open Access Journals (Sweden)

    Jason Dunham

    1999-06-01

    Full Text Available Risks of population extinction have been estimated using a variety of methods incorporating information from different spatial and temporal scales. We briefly consider how several broad classes of extinction risk assessments, including population viability analysis, incidence functions, and ranking methods integrate information on different temporal and spatial scales. In many circumstances, data from surveys of neutral genetic variability within, and among, populations can provide information useful for assessing extinction risk. Patterns of genetic variability resulting from past and present ecological and demographic events, can indicate risks of extinction that are otherwise difficult to infer from ecological and demographic analyses alone. We provide examples of how patterns of neutral genetic variability, both within, and among populations, can be used to corroborate and complement extinction risk assessments.

  19. Climate predictors of late quaternary extinctions

    DEFF Research Database (Denmark)

    Nogués-Bravo, David; Ohlemüller, Ralf; Batra, Persaram

    2010-01-01

    Between 50,000 and 3,000 years before present (BP) 65% of mammal genera weighing over 44 kg went extinct, together with a lower proportion of small mammals. Why species went extinct in such large numbers is hotly debated. One of the arguments proposes that climate changes underlie Late Quaternary...... extinctions, but global quantitative evidence for this hypothesis is still lacking. We test the potential role of global climate change on the extinction of mammals during the Late Quaternary. Our results suggest that continents with the highest climate footprint values, in other words, with climate changes...... of greater magnitudes during the Late Quaternary, witnessed more extinctions than continents with lower climate footprint values, with the exception of South America. Our results are consistent across species with different body masses, reinforcing the view that past climate changes contributed to global...

  20. A phantom extinction? New insights into extinction dynamics of the Don-hare Lepus tanaiticus.

    Science.gov (United States)

    Prost, S; Knapp, M; Flemmig, J; Hufthammer, A K; Kosintsev, P; Stiller, M; Hofreiter, M

    2010-09-01

    The Pleistocene to Holocene transition was accompanied by a worldwide extinction event affecting numerous mammalian species. Several species such as the woolly mammoth and the giant deer survived this extinction wave, only to go extinct a few thousand years later during the Holocene. Another example for such a Holocene extinction is the Don-hare, Lepus tanaiticus, which inhabited the Russian plains during the late glacial. After being slowly replaced by the extant mountain hare (Lepus timidus), it eventually went extinct during the middle Holocene. Here, we report the phylogenetic relationship of L. tanaiticus and L. timidus based on a 339-basepair (bp) fragment of the mitochondrial D-loop. Phylogenetic tree- and network reconstructions do not support L. tanaiticus and L. timidus being different species. Rather, we suggest that the two taxa represent different morphotypes of a single species and the extinction of 'L. tanaiticus' represents the disappearance of a local morphotype rather than the extinction of a species.

  1. Trophic redundancy reduces vulnerability to extinction cascades.

    Science.gov (United States)

    Sanders, Dirk; Thébault, Elisa; Kehoe, Rachel; Frank van Veen, F J

    2018-03-06

    Current species extinction rates are at unprecedentedly high levels. While human activities can be the direct cause of some extinctions, it is becoming increasingly clear that species extinctions themselves can be the cause of further extinctions, since species affect each other through the network of ecological interactions among them. There is concern that the simplification of ecosystems, due to the loss of species and ecological interactions, increases their vulnerability to such secondary extinctions. It is predicted that more complex food webs will be less vulnerable to secondary extinctions due to greater trophic redundancy that can buffer against the effects of species loss. Here, we demonstrate in a field experiment with replicated plant-insect communities, that the probability of secondary extinctions is indeed smaller in food webs that include trophic redundancy. Harvesting one species of parasitoid wasp led to secondary extinctions of other, indirectly linked, species at the same trophic level. This effect was markedly stronger in simple communities than for the same species within a more complex food web. We show that this is due to functional redundancy in the more complex food webs and confirm this mechanism with a food web simulation model by highlighting the importance of the presence and strength of trophic links providing redundancy to those links that were lost. Our results demonstrate that biodiversity loss, leading to a reduction in redundant interactions, can increase the vulnerability of ecosystems to secondary extinctions, which, when they occur, can then lead to further simplification and run-away extinction cascades. Copyright © 2018 the Author(s). Published by PNAS.

  2. Subcomponents of psychopathy have opposing correlations with punishment judgments.

    Science.gov (United States)

    Schaich Borg, Jana; Kahn, Rachel E; Sinnott-Armstrong, Walter; Kurzban, Robert; Robinson, Paul H; Kiehl, Kent A

    2013-10-01

    Psychopathy research is plagued by an enigma: Psychopaths reliably act immorally, but they also accurately report whether an action is morally wrong. The current study revealed that cooperative suppressor effects and conflicting subsets of personality traits within the construct of psychopathy might help explain this conundrum. Among a sample of adult male offenders (N = 100) who ranked deserved punishment of crimes, Psychopathy Checklist-Revised (PCL-R) total scores were not linearly correlated with deserved punishment task performance. However, these null results masked significant opposing associations between task performance and factors of psychopathy: the PCL-R Interpersonal/Affective (i.e., manipulative and callous) factor was positively associated with task performance, while the PCL-R Social Deviance (i.e., impulsive and antisocial) factor was simultaneously negatively associated with task performance. These relationships were qualified by a significant interaction where the Interpersonal/Affective traits were positively associated with task performance when Social Deviance traits were high, but Social Deviance traits were negatively associated with task performance when Interpersonal/Affective traits were low. This interaction helped reveal a significant nonlinear relationship between PCL-R total scores and task performance such that individuals with very low or very high PCL-R total scores performed better than those with middle-range PCL-R total scores. These results may explain the enigma of why individuals with very high psychopathic traits, but not other groups of antisocial individuals, usually have normal moral judgment in laboratory settings, but still behave immorally, especially in contexts where social deviance traits have strong influence.

  3. Jets and QCD

    International Nuclear Information System (INIS)

    Ali, A.; Kramer, G.

    2010-12-01

    The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e + e - collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W ± ,Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

  4. Jets and QCD

    Energy Technology Data Exchange (ETDEWEB)

    Ali, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kramer, G. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2010-12-15

    The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review we summarise the properties of quark and gluon jets and the impact of their observation on Quantum Chromodynamics, primarily the discovery of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e{sup +}e{sup -} collisions will be in the foreground of the discussion. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and pp/p anti p collisions - quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W{sup {+-}},Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics. (orig.)

  5. Jet angularity measurements for single inclusive jet production

    Science.gov (United States)

    Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

    2018-04-01

    We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

  6. Intermediate PT jet spectrometers

    International Nuclear Information System (INIS)

    Gutay, L.J.; Koltick, D.; Hauptman, J.; Stork, D.; Theodosiou, G.

    1988-01-01

    A design is presented for a limited solid angle, high resolution double arm spectrometer at 90 degree to the begin, with a vertex detector and particle identification in both arms. The jet arm is designed to accept a complete jet, and identify its substructure of sub-jets, hadrons, and leptons. The particle arm would measure e,π,K,p ratios for P T 0 to the beam for the purpose of tagging Higgs production by boson fusion, 1 gauge boson (WW, ZZ, and WZ) scattering 2 L, and other processes involving the interactions of virtual gauge bosons

  7. Latest results from JET

    International Nuclear Information System (INIS)

    Bickerton, R.J.

    1989-01-01

    The Joint European Torus (JET) is a large tokamak designed with the essential objective of obtaining and studying plasmas with parameters close to those envisaged for an eventual power-generating, nuclear-fusion reactor. JET is situated on a site near Abingdon, Oxon, UK. JET is the largest single project of the nuclear fusion research programme of the European Atomic Energy Community (EURATOM). The tokamak started operation in mid 1983 after a five year construction period. The scientific and technical results achieved so far are summarised in this article. (orig.)

  8. Oscillating acoustic streaming jet

    International Nuclear Information System (INIS)

    Moudjed, Brahim; Botton, Valery; Henry, Daniel; Millet, Severine; Ben Hadid, Hamda; Garandet, Jean-Paul

    2014-01-01

    The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence. (authors)

  9. Immediate extinction causes a less durable loss of performance than delayed extinction following either fear or appetitive conditioning

    OpenAIRE

    Woods, Amanda M.; Bouton, Mark E.

    2008-01-01

    Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In all experiments, conditioning and extinction were accomplished in single sessions, and retention testing took place 24 h after extinction. In both f...

  10. The Energetic Neutral Atoms of the "Croissant" Heliosphere with Jets

    Science.gov (United States)

    Kornbleuth, M. Z.; Opher, M.; Michael, A.

    2017-12-01

    Opher et al. (2015) suggests the heliosphere may have two jets in the tail-ward direction driven to the north and south. This new model, the "Croissant Heliosphere", is in contrast to the classically accepted view of a comet-like tail. We investigate the effect of the heliosphere with jets model on energetic neutral atom (ENA) maps. Regardless of the existence of a split tail, other models show heliosheath plasma confined by the toroidal magnetic field in a "slinky" structure, similar to astrophysical jets bent by the interstellar medium. Therefore, the confinement of the plasma should appear in the ENA maps. ENA maps from the Interstellar Boundary Explorer (IBEX) have recently shown two high latitude lobes with excess ENA flux at higher energies in the tail of the heliosphere. These lobes could be a signature of the two jet structure of the heliosphere, while some have argued they are cause by the fast/slow solar wind profile. Here we present the ENA maps of the "Croissant Heliosphere" using initially a uniform solar wind. We incorporate pick-up ions (PUIs) into our model based on the kinetic modeling of Malama et al. (2006). We include the extinction of PUIs in the heliosheath and describe a locally created PUI population resulting from this extinction process. Additionally, we include the angular dependence of the PUIs based on the work of Vasyliunas & Siscoe (1976). With our model, we find that, in the presence of a uniform solar wind, the "heliosphere with jets" model is able to qualitatively reproduce the lobe structure of the tail seen in IBEX measurements. Turbulence also manifests itself within the lobes of the simulated ENA maps on the order of years. Finally we will present ENA maps using a time-dependent model of the heliosphere with the inclusion of solar cycle.

  11. Extinction produces context inhibition and multiple-context extinction reduces response recovery in human predictive learning.

    Science.gov (United States)

    Glautier, Steven; Elgueta, Tito; Nelson, James Byron

    2013-12-01

    Two experiments with human participants were used to investigate recovery of an extinguished learned response after a context change using ABC designs. In an ABC design, the context changes over the three successive stages of acquisition (context A), extinction (context B), and test (context C). In both experiments, we found reduced recovery in groups that had extinction in multiple contexts, and that the extinction contexts acquired inhibitory strength. These results confirm those of previous investigations, that multiple-context extinction can produce less response recovery than single-context extinction, and they also provide new evidence for the involvement of contextual inhibitory processes in extinction in humans. The foregoing results are broadly in line with a protection-from-extinction account of response recovery. Yet, despite the fact that we detected contextual inhibition, predictions based on protection-from-extinction were not fully reliable for the single- and multiple-context group differences that we observed in (1) rates of extinction and (2) the strength of context inhibition. Thus, although evidence was obtained for a protection-from-extinction account of response recovery, this account can not explain all of the data.

  12. Estimating extinction using unsupervised machine learning

    Science.gov (United States)

    Meingast, Stefan; Lombardi, Marco; Alves, João

    2017-05-01

    Dust extinction is the most robust tracer of the gas distribution in the interstellar medium, but measuring extinction is limited by the systematic uncertainties involved in estimating the intrinsic colors to background stars. In this paper we present a new technique, Pnicer, that estimates intrinsic colors and extinction for individual stars using unsupervised machine learning algorithms. This new method aims to be free from any priors with respect to the column density and intrinsic color distribution. It is applicable to any combination of parameters and works in arbitrary numbers of dimensions. Furthermore, it is not restricted to color space. Extinction toward single sources is determined by fitting Gaussian mixture models along the extinction vector to (extinction-free) control field observations. In this way it becomes possible to describe the extinction for observed sources with probability densities, rather than a single value. Pnicer effectively eliminates known biases found in similar methods and outperforms them in cases of deep observational data where the number of background galaxies is significant, or when a large number of parameters is used to break degeneracies in the intrinsic color distributions. This new method remains computationally competitive, making it possible to correctly de-redden millions of sources within a matter of seconds. With the ever-increasing number of large-scale high-sensitivity imaging surveys, Pnicer offers a fast and reliable way to efficiently calculate extinction for arbitrary parameter combinations without prior information on source characteristics. The Pnicer software package also offers access to the well-established Nicer technique in a simple unified interface and is capable of building extinction maps including the Nicest correction for cloud substructure. Pnicer is offered to the community as an open-source software solution and is entirely written in Python.

  13. Measurements of Jets in ALICE

    CERN Document Server

    Nattrass, Christine

    2016-01-01

    The ALICE detector can be used for measurements of jets in pp , p Pb, and Pb–Pb collisions. Measurements of jets in pp collisions are consis- tent with expectations from perturbative calculations and jets in p Pb scale with the number of nucleon–nucleon collisions, indicating that cold nuclear matter effects are not observed for jets. Measurements in Pb–Pb collisions demonstrate suppression of jets relative to expectations from binary scaling to the equivalent number of nucleon–nucleon collisions

  14. Jet lag prevention

    Science.gov (United States)

    ... lose time. Symptoms of jet lag include: Trouble falling asleep or waking up Tiredness during the day ... at your destination. For longer trips, before you leave, try to adapt to the time schedule of ...

  15. Intermonsoonal equatorial jets

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.

    , respectively. Hydrographic features and transport computations favour a well developed equatorial jet during both seasons. The net surface eastward and subsurface westward flows are well balanced during the premonsoon transition period and appear...

  16. Amount of fear extinction changes its underlying mechanisms.

    Science.gov (United States)

    An, Bobae; Kim, Jihye; Park, Kyungjoon; Lee, Sukwon; Song, Sukwoon; Choi, Sukwoo

    2017-07-03

    There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.

  17. The JET divertor coil

    International Nuclear Information System (INIS)

    Last, J.R.; Froger, C.; Sborchia, C.

    1989-01-01

    The divertor coil is mounted inside the Jet vacuum vessel and is able to carry 1 MA turns. It is of conventional construction - water cooled copper, epoxy glass insulation -and is contained in a thin stainless steel case. The coil has to be assembled, insulated and encased inside the Jet vacuum vessel. A description of the coil is given, together with technical information (including mechanical effects on the vacuum vessel), an outline of the manufacture process and a time schedule. (author)

  18. Pellet injectors for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buechl, K.; Lang, R.S.; Schilling, H.B.; Ulrich, M.

    1981-09-01

    Pellet injection for the purpose of refuelling and diagnostic of fusion experiments is considered for the parameters of JET. The feasibility of injectors for single pellets and for quasistationary refuelling is discussed. Model calculations on pellet ablation with JET parameters show the required pellet velocity ( 3 ). For single pellet injection a light gas gun, for refuelling a centrifuge accelerator is proposed. For the latter the mechanical stress problems are discussed. Control and data acquisition systems are outlined. (orig.)

  19. Protostellar Jets in Context

    CERN Document Server

    Tsinganos, Kanaris; Stute, Matthias

    2009-01-01

    This volume contains the proceedings of the Conference Protostellar Jets in Context held by the JETSET Marie Curie Research Training Network in July 2008. This meeting not only served to showcase some of the network's achievements but was also a platform to hear from, discuss and debate the recent findings of world-class astrophysicists in the field of protostellar jet research. Jets from young stars are of course not an isolated astrophysical phenomenon. It is known that objects as diverse as young brown dwarfs, planetary nebulae, symbiotic stars, micro-quasars, AGN, and gamma-ray bursters produce jets. Thus in a series of talks, protostellar jets were put in context by comparing them with their often much larger brethren and also by considering the ubiquitous accretion disks that seem to be necessary for their formation. With this spectrum of contributions on observations and the theory of astrophysical jets and accretion disks, this book serves as a comprehensive reference work for researchers and students...

  20. Temporal factors in the extinction of fear in inbred mouse strains differing in extinction efficacy.

    Science.gov (United States)

    MacPherson, Kathryn; Whittle, Nigel; Camp, Marguerite; Gunduz-Cinar, Ozge; Singewald, Nicolas; Holmes, Andrew

    2013-07-05

    Various neuropsychiatric conditions, including posttraumatic stress disorder (PTSD), are characterized by deficient fear extinction, but individuals differ greatly in risk for these. While there is growing evidence that fear extinction is influenced by certain procedural variables, it is unclear how these influences might vary across individuals and subpopulations. To model individual differences in fear extinction, prior studies identified a strain of inbred mouse, 129S1/SvImJ (S1), which exhibits a profound deficit in fear extinction, as compared to other inbred strains, such as C57BL/6J (B6). Here, we assessed the effects of procedural variables on the impaired extinction phenotype of the S1 strain and, by comparison, the extinction-intact B6 strain. The variables studied were 1) the interval between conditioning and extinction, 2) the interval between cues during extinction training, 3) single-cue exposure before extinction training, and 4) extinction of a second-order conditioned cue. Conducting extinction training soon after ('immediately') conditioning attenuated fear retrieval in S1 mice and impaired extinction in B6 mice. Spacing cue presentations with long inter-trial intervals during extinction training augmented fear in S1 and B6 mice. The effect of spacing was lost with one-trial fear conditioning in B6, but not S1 mice. A single exposure to a conditioned cue before extinction training did not alter extinction retrieval, either in B6 or S1 mice. Both the S1 and B6 strains exhibited robust second-order fear conditioning, in which a cue associated with footshock was sufficient to serve as a conditioned exciter to condition a fear association to a second cue. B6 mice extinguished the fear response to the second-order conditioned cue, but S1 mice failed to do so. These data provide further evidence that fear extinction is strongly influenced by multiple procedural variables and is so in a highly strain-dependent manner. This suggests that the efficacy of

  1. Jet supercooling and molecular jet spectroscopy

    International Nuclear Information System (INIS)

    Wharton, L.; Levy, D.

    1979-01-01

    The marriage of the laser and the seeded supersonic jet has generated a family of new optical spectroscopic results. We shall discuss the essential features of the technique and some results. The results will include structural and dynamical views of NO 2 , NaAr, and I 2 -noble gas complexes. The extension of the method to heavier systems is illustrated with free base phthalocyanine

  2. Hospital autopsy: Endangered or extinct?

    Science.gov (United States)

    Turnbull, Angus; Osborn, Michael; Nicholas, Nick

    2015-08-01

    To determine the hospital autopsy rate for the UK in 2013. A study of data from a 'Freedom of Information' request to all (n=186) acute NHS Trusts within England (n=160), NHS Boards in Scotland (n=14) and Wales (n=7) and Social Care Trusts in Northern Ireland (n=5). Hospital autopsy rates were calculated from the number of hospital autopsies performed in 2013 as a percentage of total inpatient deaths in the Trust that year. The UK response rate was 99% (n=184), yielding a mean autopsy rate of 0.69%. The mean rates were 0.51% (England), 2.13% (Scotland), 0.65% (Wales) and 0.46% (Northern Ireland). 23% (n=38) of all included respondents had a rate of 0% and 86% (n=143) a rate less than 1%. The decline in hospital autopsy has continued relentlessly and, for better or for worse, the practice is on the verge of extinction in the UK. The study highlights to health professionals and policy makers the magnitude of this decline. Further research should investigate the impact of this on patient safety, clinical audit, public health and medical education. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  3. Extinction from a rationalist perspective.

    Science.gov (United States)

    Gallistel, C R

    2012-05-01

    The merging of the computational theory of mind and evolutionary thinking leads to a kind of rationalism, in which enduring truths about the world have become implicit in the computations that enable the brain to cope with the experienced world. The dead reckoning computation, for example, is implemented within the brains of animals as one of the mechanisms that enables them to learn where they are (Gallistel, 1990, 1995). It integrates a velocity signal with respect to a time signal. Thus, the manner in which position and velocity relate to one another in the world is reflected in the manner in which signals representing those variables are processed in the brain. I use principles of information theory and Bayesian inference to derive from other simple principles explanations for: (1) the failure of partial reinforcement to increase reinforcements to acquisition; (2) the partial reinforcement extinction effect; (3) spontaneous recovery; (4) renewal; (5) reinstatement; (6) resurgence (aka facilitated reacquisition). Like the principle underlying dead-reckoning, these principles are grounded in analytic considerations. They are the kind of enduring truths about the world that are likely to have shaped the brain's computations. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. A PLIF and PIV study of liquid mixing enhanced by a lateral synthetic jet pair

    International Nuclear Information System (INIS)

    Xia Qingfeng; Zhong Shan

    2012-01-01

    Highlights: ► Enhancement of mixing between two water streams in a planar channel by means of a lateral synthetic jet pair is studied using PLIF and PIV. ► The excellent mixing observed is largely caused by a strong interaction between the opposing vortex pairs produced by the lateral synthetic jets. ► The synthetic jet operating conditions, at which a nearly homogenous mixing is achieved, are also identified and they are expressed in terms of a functional relationship. - Abstract: In this paper, enhancement of mixing between two water streams of the same flow rate in a planar channel by means of a lateral synthetic jet pair is studied at a net flow Reynolds number of 83 using PLIF and PIV. The synthetic jet pair is operated 180° out-of-phase at a range of actuation frequencies and displacements, with the latter being characterized by the dimensionless stroke length. The extent of mixing is evaluated using PLIF data at a location further downstream in the mixing channel. It is found that at a fixed actuation frequency a higher dimensionless stroke length produces a better mixing, and as the actuation frequency increases a lower dimensionless stroke length is required to achieve a given mixing degree. At a sufficiently high frequency or dimensionless stroke length, a nearly homogenous mixing with a mixing degree greater than 0.9 can be obtained. A functional relationship between actuation frequency and dimensionless stroke length is also obtained by best fitting the experimental data, which can be used for selecting the synthetic jet operating conditions to ensure a good mixing. Furthermore, both PLIF and PIV results show that each synthetic jet actuation cycle produce two opposing vortex pairs, which play an important role in prompting mixing between the two fluid streams. The excellent mixing obtained at a high frequency or a high dimensionless stroke length is found to be largely caused by a strong interaction between these opposing vortex pairs.

  5. Stress before extinction learning enhances and generalizes extinction memory in a predictive learning task.

    Science.gov (United States)

    Meir Drexler, Shira; Hamacher-Dang, Tanja C; Wolf, Oliver T

    2017-05-01

    In extinction learning, the individual learns that a previously acquired association (e.g. between a threat and its predictor) is no longer valid. This learning is the principle underlying many cognitive-behavioral psychotherapeutic treatments, e.g. 'exposure therapy'. However, extinction is often highly-context dependent, leading to renewal (relapse of extinguished conditioned response following context change). We have previously shown that post-extinction stress leads to a more context-dependent extinction memory in a predictive learning task. Yet as stress prior to learning can impair the integration of contextual cues, here we aim to create a more generalized extinction memory by inducing stress prior to extinction. Forty-nine men and women learned the associations between stimuli and outcomes in a predictive learning task (day 1), extinguished them shortly after an exposure to a stress/control condition (day 2), and were tested for renewal (day 3). No group differences were seen in acquisition and extinction learning, and a renewal effect was present in both groups. However, the groups differed in the strength and context-dependency of the extinction memory. Compared to the control group, the stress group showed an overall reduced recovery of responding to the extinguished stimuli, in particular in the acquisition context. These results, together with our previous findings, demonstrate that the effects of stress exposure on extinction memory depend on its timing. While post-extinction stress makes the memory more context-bound, pre-extinction stress strengthens its consolidation for the acquisition context as well, making it potentially more resistant to relapse. These results have implications for the use of glucocorticoids as extinction-enhancers in exposure therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Interstellar extinction in the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    Nandy, K.; McLachlan, A.; Thompson, G.I.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

    1982-01-01

    IUE observations of three considerably reddened stars located near the core of the Small Magellanic Cloud and of two comparison stars which are also SMC members are presented. This region contains a considerable amount of dust. The UV spectrum of one of the reddened stars (BBB 338) shows the lambda 2200 feature characteristic of the Galactic extinction curve. This absorption feature is not obvious in the UV spectra of the other two reddened stars. Due to lack of a suitable comparison star it has not been possible to measure the UV extinction of BBB 338. The extinction curves derived for the other two reddened SMC members differ from the mean Galactic law in that they exhibit very weak or absent lambda 2200 and much higher values of far-UV extinction. These differences are greater than have been found for stars in the Large Magellanic Cloud, confirming earlier observations by others. (author)

  7. Anthropogenic stressors and riverine fish extinctions

    NARCIS (Netherlands)

    Dias, M.S.; Tedesco, P.A.; Hugueny, B.; Jézéquel, C.; Beauchard, O.; Brosse, S.; Oberdorff, T.

    2017-01-01

    Human activities are often implicated in the contemporary extinction of contemporary species. Concerningriverine fishes, the major biotic and abiotic threats widely cited include introduction of non-nativespecies, habitat fragmentation and homogenization in stream flow dynamics due to the damming

  8. Are marine and nonmarine extinctions correlated?

    Science.gov (United States)

    Rampino, Michael R.

    Recent papers in Eos have debated the possible relationships between marine mass extinctions, comet showers, and volcanism [Alvarez, 1986; Officer and Grieve, 1986], and ail three might be linked [Rampino, 1987]. Moreover, as Officer and Grieve [ 1986] point out, various other causes have been suggested for given extinction events, including changes in climate, ocean circulation, and sea level fluctuations, possibly related to plate tectonics and continental positions. Also under debate is the issue of whether mass extinctions were gradual, stepped, or geologically sudden events (see, for example, Hut et al. [1987]). A missing ingredient thus far in these debates has been the record of faunal diversity of nonmarine animals. Does this show any agreement with the marine extinction record?

  9. Extinction vulnerability of coral reef fishes.

    Science.gov (United States)

    Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron Macneil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

    2011-04-01

    With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. © 2011 Blackwell Publishing Ltd/CNRS.

  10. Oxytocin in the amygdala and not the prefrontal cortex enhances fear and impairs extinction in the juvenile rat.

    Science.gov (United States)

    Kritman, Milly; Lahoud, Nisrine; Maroun, Mouna

    2017-05-01

    A growing body of evidence suggests that the hypothalamic neuropeptide oxytocin (OT), aside from its central role in the regulation of social behavior, reduces fear and anxiety. The functional and opposing interactions of the medial prefrontal cortex (mPFC) and the amygdala in regulation of fear provide a unique experimental setting to examine the effects of OT on fear and extinction. Recent evidence suggests that in the adult animal OT can play a dual role in the regulation of fear leading to contrasting effects on fear depending on the manipulated brain region and the time of manipulations. The OT system is one of the systems that undergoes major changes throughout development, however, its role in regulating fear in young animals has not been widely explored. We recently showed that the mechanisms of extinction, and specifically engagement of the mPFC in extinction, are not identical in adult and juvenile animals. Thus, the purpose of this study was to elucidate the effects of OT on fear and extinction in juvenile animals. To that end, we determine extinction, by measuring freezing at different time points, following microinjection of the OT agonist, TGOT, into the mPFC, the basolateral and the central nuclei of the amygdala (BLA and CeA, respectively). The results show that whereas TGOT microinjections into the IL-mPFC did not affect extinction, microinjections into the amygdala were mainly associated with enhanced fear and impaired extinction. These results further emphasize the differences between adult and juvenile brains. Copyright © 2017. Published by Elsevier Inc.

  11. Interstellar Silicon Depletion and the Ultraviolet Extinction

    Science.gov (United States)

    Mishra, Ajay; Li, Aigen

    2018-01-01

    Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 Å interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates [Si/H]dust and the 2175 Å bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance [Si/H]gas is known. We derive [Si/H]dust either from [Si/H]ISM - [Si/H]gas or from the Kramers- Kronig relation which relates the wavelength-integrated extinction to the total dust volume, where [Si/H]ISM is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive [Si/H]dust from fi�tting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We fi�nd that in all three cases [Si/H]dust shows no correlation with the 2175 Å bump, while the carbon depletion [C/H]dust tends to correlate with the 2175 Å bump. This supports carbon grains instead of silicates as the possible carrier of the 2175 Å bump. We also �find that neither [Si/H]dust nor [C/H]dust alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

  12. Post-Retrieval Extinction Attenuates Cocaine Memories

    OpenAIRE

    Sartor, Gregory C; Aston-Jones, Gary

    2013-01-01

    Recent studies have shown that post-retrieval extinction training attenuates fear and reward-related memories in both humans and rodents. This noninvasive, behavioral approach has the potential to be used in clinical settings to treat maladaptive memories that underlie several psychiatric disorders, including drug addiction. However, few studies to date have used a post-retrieval extinction approach to attenuate addiction-related memories. In the current study, we attempted to disrupt cocaine...

  13. Modelling the extinction of Steller's sea cow

    OpenAIRE

    Turvey, S.T; Risley, C.L

    2005-01-01

    Steller's sea cow, a giant sirenian discovered in 1741 and extinct by 1768, is one of the few megafaunal mammal species to have died out during the historical period. The species is traditionally considered to have been exterminated by ‘blitzkrieg’-style direct overharvesting for food, but it has also been proposed that its extinction resulted from a sea urchin population explosion triggered by extirpation of local sea otter populations that eliminated the shallow-water kelps on which sea cow...

  14. A model for evolution and extinction

    OpenAIRE

    Roberts, Bruce W.; Newman, M. E. J.

    1995-01-01

    We present a model for evolution and extinction in large ecosystems. The model incorporates the effects of interactions between species and the influences of abiotic environmental factors. We study the properties of the model by approximate analytic solution and also by numerical simulation, and use it to make predictions about the distribution of extinctions and species lifetimes that we would expect to see in real ecosystems. It should be possible to test these predictions against the fossi...

  15. The extinction of the West African lion: whose responsibility?

    NARCIS (Netherlands)

    Nollkaemper, A.

    2014-01-01

    A recently published study showed that the lion in West Africa is now critically endangered and faces extinction. From one angle, this would be just one of the large (though unknown) number of species that has previously faced extinction or has even become extinct. But the risk of extinction of some

  16. Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

    Science.gov (United States)

    Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…

  17. AESoP: Astronomical Extinction Spectrophotometer

    Science.gov (United States)

    Linford, Justin; McGraw, J.; Zimmer, P.; Ackermann, M.; Fitch, J.

    2009-01-01

    The Earth's atmosphere is a major obstruction to the precision and accuracy of ground-based photometry. The atmosphere removes light from astronomical objects both by absorption and scattering by constituent molecules, aerosols and clouds. These effects can change significantly over short time periods and over modest angles on the sky. To further understand these effects, the UNM Measurement Astrophysics Group has designed, built and recently deployed the Astronomical Extinction Spectrophotometer (AESoP), a 100mm objective grating spectrometer. By monitoring bright stars in sensibly the same direction as a larger photometric telescope is observing, AESoP will measure the wavelength-dependent extinction due to the Earth's atmosphere from 450nm to 900nm on time scales of approximately one minute. The collocated Astronomical LIDAR for Extinction (ALE) provides a high-precision monochromatic extinction measurement at 527nm. Knowing the extinction at a single wavelength allows us to pin the relative spectra generated by AESoP. These extinction spectra can then be integrated over the bandpass of the photometric telescope system to create real time corrections of observations. We present the design and construction of AESoP along with the preliminary results of our first combined observing campaign. This effort is our first step toward breaking the 1% photometry barrier. This project is funded by AFRL Grant FA9451-04-2-0355

  18. How does climate change cause extinction?

    Science.gov (United States)

    Cahill, Abigail E; Aiello-Lammens, Matthew E; Fisher-Reid, M Caitlin; Hua, Xia; Karanewsky, Caitlin J; Ryu, Hae Yeong; Sbeglia, Gena C; Spagnolo, Fabrizio; Waldron, John B; Warsi, Omar; Wiens, John J

    2013-01-07

    Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years. But what will actually cause these extinctions? For example, will it be limited physiological tolerance to high temperatures, changing biotic interactions or other factors? Here, we systematically review the proximate causes of climate-change related extinctions and their empirical support. We find 136 case studies of climatic impacts that are potentially relevant to this topic. However, only seven identified proximate causes of demonstrated local extinctions due to anthropogenic climate change. Among these seven studies, the proximate causes vary widely. Surprisingly, none show a straightforward relationship between local extinction and limited tolerances to high temperature. Instead, many studies implicate species interactions as an important proximate cause, especially decreases in food availability. We find very similar patterns in studies showing decreases in abundance associated with climate change, and in those studies showing impacts of climatic oscillations. Collectively, these results highlight our disturbingly limited knowledge of this crucial issue but also support the idea that changing species interactions are an important cause of documented population declines and extinctions related to climate change. Finally, we briefly outline general research strategies for identifying these proximate causes in future studies.

  19. Extinction rates in North American freshwater fishes, 1900-2010

    Science.gov (United States)

    Burkhead, Noel M.

    2012-01-01

    Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

  20. The edentulous mandible opposing maxillary natural teeth: treatment considerations utilizing implant overdentures.

    Science.gov (United States)

    Winkler, S; Monasky, G E

    1993-01-01

    The restoration of the edentulous mandible opposing all or part of the maxillary natural dentition with implant overdentures is described. There are many situations in which the maxillary teeth opposing an edentulous mandible can and should be retained. Mandibular implant overdentures can be utilized as long as health considerations, morphologic features of the resorbed mandible, and maxillomandibular jaw relationships are satisfactory.

  1. The Late Ordovician Extinction: How it became the best understood of the five major extinctions.

    Science.gov (United States)

    Sheehan, P.

    2003-04-01

    The end Ordovician extinction has become arguably the best-understood major extinction event in Earth History. A plethora of workers have established the pattern of faunal change and causes of the extinction with remarkably little disagreement. The first indication of increased extinction at the end of the Ordovician was a graph of global diversity patterns by Norman Newell in 1967, although he did not recognize it as a major event. The presence of a major extinction event became clear as William Berry and Art Boucot assembled data for Silurian correlation charts in the late 1960s. The first reports of North African glaciation in the late 1960s provided a cause for the extinction and study of the event snowballed. It was no accident that recognition of the extinction began in North America, because it was there that the extinction completely overturned faunas in the epicontinental seas. Glacio-eustatic regression of shallow seaway coincided with the disappearance of endemic Laurentian faunas and replacement by a highly cosmopolitan fauna in the Silurian. Once the event was established in North America, paleontologists soon found evidence of the event around the globe. The well-documented Hirnantia Fauna was found to correspond to the glacial interval, and Pat Brenchley soon recognized that there were two pulses of extinction, at the beginning and end of the glaciation. At the same time that the faunal changes were being documented geologic studies of the glaciation provided information on the environmental changes associated with the extinction. The timing of the glacial maximum was established in Africa and by the presence of dropstones in high latitude marine rocks. The 1990s saw geochemical techniques employed that allowed examination of atmospheric CO2 and temperature changes. In many places carbonate deposition declined. Glacio-eustatic regression was obvious in many areas, and a sea-level decline in the range of 50-100 m was established. Shallow

  2. Immediate Extinction Causes a Less Durable Loss of Performance than Delayed Extinction following Either Fear or Appetitive Conditioning

    Science.gov (United States)

    Woods, Amanda M.; Bouton, Mark E.

    2008-01-01

    Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In…

  3. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.; Kupschus, P.

    1984-09-01

    The report is in sections, as follows. (1) Introduction and summary. (2) A brief description of the origins of the JET Project within the EURATOM fusion programme and the objectives and aims of the device. The basic JET design and the overall philosophy of operation are explained and the first six months of operation of the machine are summarised. The Project Team Structure adopted for the Operation Phase is set out. Finally, in order to set JET's progress in context, other large tokamaks throughout the world and their achievements are briefly described. (3) The activities and progress within the Operation and Development Department are set out; particularly relating to its responsibilities for the operation and maintenance of the tokamak and for developing the necessary engineering equipment to enhance the machine to full performance. (4) The activities and progress within the Scientific Department are described; particularly relating to the specification, procurement and operation of diagnostic equipment; definition and execution of the programme; and the interpretation of experimental results. (5) JET's programme plans for the immediate future and a broad outline of the JET Development Plan to 1990 are given. (author)

  4. Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

    OpenAIRE

    Boukezzi, Sarah; Silva, Catarina; Nazarian, Bruno; Rousseau, Pierre-François; Guedj, Eric; Valenzuela-Moguillansky, Camila; Khalfa, Stéphanie

    2017-01-01

    Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to ...

  5. JET Joint Undertaking

    International Nuclear Information System (INIS)

    Keen, B.E.

    1986-03-01

    This is an overview summary of the scientific and technical advances at JET during the year 1985, supplemented by appendices of detailed contributions (in preprint form) of eight of the more important JET articles produced during that year. It is aimed not only at specialists and experts but also at a more general scientific community. Thus there is a brief summary of the background to the project, a description of the basic objectives of JET and the principle design features of the machine. The new structure of the Project Team is also explained. Developments and future plans are included. Improvements considered are those which are designed to overcome certain limitations encountered generally on Tokamaks, particularly those concerned with density limits, with plasma MHD behaviour, with impurities and with plasma transport. There is also a complete list of articles, reports and conference papers published in 1985 - there are 167 such items listed. (UK)

  6. Extinction Generates Outcome-Specific Conditioned Inhibition.

    Science.gov (United States)

    Laurent, Vincent; Chieng, Billy; Balleine, Bernard W

    2016-12-05

    Extinction involves altering a previously established predictive relationship between a cue and its outcome by repeatedly presenting that cue alone. Although it is widely accepted that extinction generates some form of inhibitory learning [1-4], direct evidence for this claim has been lacking, and the nature of the associative changes induced by extinction have, therefore, remained a matter of debate [5-8]. In the current experiments, we used a novel behavioral approach that we recently developed and that provides a direct measure of conditioned inhibition [9] to compare the influence of extinguished and non-extinguished cues on choice between goal-directed actions. Using this approach, we provide direct evidence that extinction generates outcome-specific conditioned inhibition. Furthermore, we demonstrate that this inhibitory learning is controlled by the infralimbic cortex (IL); inactivation of the IL using M4 DREADDs abolished outcome-specific inhibition and rendered the cue excitatory. Importantly, we found that context modulated this inhibition. Outside its extinction context, the cue was excitatory and functioned as a specific predictor of its previously associated outcome, biasing choice toward actions earning the same outcome. In its extinction context, however, the cue acted as a specific inhibitor and biased choice toward actions earning different outcomes. Context modulation of these excitatory and inhibitory memories was mediated by the dorsal hippocampus (HPC), suggesting that the HPC and IL act in concert to control the influence of conditioned inhibitors on choice. These findings demonstrate for the first time that extinction turns a cue into a net inhibitor that can influence choice via counterfactual action-outcome associations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Elevational distribution and extinction risk in birds.

    Directory of Open Access Journals (Sweden)

    Rachel L White

    Full Text Available Mountainous regions are hotspots of terrestrial biodiversity. Unlike islands, which have been the focus of extensive research on extinction dynamics, fewer studies have examined mountain ranges even though they face increasing threats from human pressures - notably habitat conversion and climate change. Limits to the taxonomic and geographical extent and resolution of previously available information have precluded an explicit assessment of the relative role of elevational distribution in determining extinction risk. We use a new global species-level avian database to quantify the influence of elevational distribution (range, maximum and midpoint on extinction risk in birds at the global scale. We also tested this relationship within biogeographic realms, higher taxonomic levels, and across phylogenetic contrasts. Potential confounding variables (i.e. phylogenetic, distributional, morphological, life history and niche breadth were also tested and controlled for. We show that the three measures of elevational distribution are strong negative predictors of avian extinction risk, with elevational range comparable and complementary to that of geographical range size. Extinction risk was also found to be positively associated with body weight, development and adult survival, but negatively associated with reproduction and niche breadth. The robust and consistent findings from this study demonstrate the importance of elevational distribution as a key driver of variation in extinction dynamics in birds. Our results also highlight elevational distribution as a missing criterion in current schemes for quantifying extinction risk and setting species conservation priorities in birds. Further research is recommended to test for generality across non-avian taxa, which will require an advance in our knowledge of species' current elevational ranges and increased efforts to digitise and centralise such data.

  8. Jet shapes in hadron and electron colliders

    International Nuclear Information System (INIS)

    Wainer, N.

    1993-05-01

    High energy jets are observed both in hadronic machines like the Tevatron and electron machines like LEP. These jets have an extended structure in phase space which can be measured. This distribution is usually called the jet shape. There is an intrinsic relation between jet variables, like energy and direction, the jet algorithm used, and the jet shape. Jet shape differences can be used to separate quark and gluon jets

  9. Galaxies with jet streams

    International Nuclear Information System (INIS)

    Breuer, R.

    1981-01-01

    Describes recent research work on supersonic gas flow. Notable examples have been observed in cosmic radio sources, where jet streams of galactic dimensions sometimes occur, apparently as the result of interaction between neighbouring galaxies. The current theory of jet behaviour has been convincingly demonstrated using computer simulation. The surprisingly long-term stability is related to the supersonic velocity, and is analagous to the way in which an Appollo spacecraft re-entering the atmosphere supersonically is protected by the gas from the burning shield. (G.F.F.)

  10. OPAL Jet Chamber Prototype

    CERN Multimedia

    OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. OPAL's central tracking system consists of (in order of increasing radius) a silicon microvertex detector, a vertex detector, a jet chamber, and z-chambers. All the tracking detectors work by observing the ionization of atoms by charged particles passing by: when the atoms are ionized, electrons are knocked out of their atomic orbitals, and are then able to move freely in the detector. These ionization electrons are detected in the dirfferent parts of the tracking system. This piece is a prototype of the jet chambers

  11. Jet pump assisted artery

    Science.gov (United States)

    1975-01-01

    A procedure for priming an arterial heat pump is reported; the procedure also has a means for maintaining the pump in a primed state. This concept utilizes a capillary driven jet pump to create the necessary suction to fill the artery. Basically, the jet pump consists of a venturi or nozzle-diffuser type constriction in the vapor passage. The throat of this venturi is connected to the artery. Thus vapor, gas, liquid, or a combination of the above is pumped continuously out of the artery. As a result, the artery is always filled with liquid and an adequate supply of working fluid is provided to the evaporator of the heat pipe.

  12. Extinctions. Paleontological baselines for evaluating extinction risk in the modern oceans.

    Science.gov (United States)

    Finnegan, Seth; Anderson, Sean C; Harnik, Paul G; Simpson, Carl; Tittensor, Derek P; Byrnes, Jarrett E; Finkel, Zoe V; Lindberg, David R; Liow, Lee Hsiang; Lockwood, Rowan; Lotze, Heike K; McClain, Craig R; McGuire, Jenny L; O'Dea, Aaron; Pandolfi, John M

    2015-05-01

    Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over 23 million years, taxonomic membership and geographic range size consistently explain a large proportion of extinction risk variation in six major taxonomic groups. We assess intrinsic risk-extinction risk predicted by paleontologically calibrated models-for modern genera in these groups. Mapping the geographic distribution of these genera identifies coastal biogeographic provinces where fauna with high intrinsic risk are strongly affected by human activity or climate change. Such regions are disproportionately in the tropics, raising the possibility that these ecosystems may be particularly vulnerable to future extinctions. Intrinsic risk provides a prehuman baseline for considering current threats to marine biodiversity. Copyright © 2015, American Association for the Advancement of Science.

  13. Facilitation of extinction and re-extinction of operant behavior in mice by chlordiazepoxide and D-cycloserine.

    Science.gov (United States)

    Leslie, Julian C; Norwood, Kelly

    2013-05-01

    The aim was to compare operant extinction with re-extinction following re-acquisition and to investigate neuropharmacological mechanisms through administration of drugs potentiating GABAergic or glutamatergic systems. Groups of C57Bl/6 mice were trained to lever press for food on a fixed ratio schedule, then extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine administration (15mg/kg in each case), then retrained to lever press for food, then re-extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine. Under vehicle injections, extinction and re-extinction curves were indistinguishable, but drug treatments showed that there was less resistance to extinction in the re-extinction phase. Chlordiazepoxide facilitated extinction and re-extinction, with an earlier effect during re-extinction. d-Cycloserine also facilitated extinction and re-extinction, with some evidence of an earlier effect during re-extinction. These results replicate and extend earlier findings with operant extinction, but differ from some previous reports of d-cycloserine on re-extinction of Pavlovian conditioned fear. Implications for accounts of the similarities and differences between neural mechanisms of extinction following either Pavlovian or operant conditioning, and applications of these findings, are discussed. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Fluoxetine Facilitates Fear Extinction Through Amygdala Endocannabinoids

    Science.gov (United States)

    Gunduz-Cinar, Ozge; Flynn, Shaun; Brockway, Emma; Kaugars, Katherine; Baldi, Rita; Ramikie, Teniel S; Cinar, Resat; Kunos, George; Patel, Sachin; Holmes, Andrew

    2016-01-01

    Pharmacologically elevating brain endocannabinoids (eCBs) share anxiolytic and fear extinction-facilitating properties with classical therapeutics, including the selective serotonin reuptake inhibitor, fluoxetine. There are also known functional interactions between the eCB and serotonin systems and preliminary evidence that antidepressants cause alterations in brain eCBs. However, the potential role of eCBs in mediating the facilitatory effects of fluoxetine on fear extinction has not been established. Here, to test for a possible mechanistic contribution of eCBs to fluoxetine's proextinction effects, we integrated biochemical, electrophysiological, pharmacological, and behavioral techniques, using the extinction-impaired 129S1/Sv1mJ mouse strain. Chronic fluoxetine treatment produced a significant and selective increase in levels of anandamide in the BLA, and an associated decrease in activity of the anandamide-catabolizing enzyme, fatty acid amide hydrolase. Slice electrophysiological recordings showed that fluoxetine-induced increases in anandamide were associated with the amplification of eCB-mediated tonic constraint of inhibitory, but not excitatory, transmission in the BLA. Behaviorally, chronic fluoxetine facilitated extinction retrieval in a manner that was prevented by systemic or BLA-specific blockade of CB1 receptors. In contrast to fluoxetine, citalopram treatment did not increase BLA eCBs or facilitate extinction. Taken together, these findings reveal a novel, obligatory role for amygdala eCBs in the proextinction effects of a major pharmacotherapy for trauma- and stressor-related disorders and anxiety disorders. PMID:26514583

  15. Neural signals of vicarious extinction learning.

    Science.gov (United States)

    Golkar, Armita; Haaker, Jan; Selbing, Ida; Olsson, Andreas

    2016-10-01

    Social transmission of both threat and safety is ubiquitous, but little is known about the neural circuitry underlying vicarious safety learning. This is surprising given that these processes are critical to flexibly adapt to a changeable environment. To address how the expression of previously learned fears can be modified by the transmission of social information, two conditioned stimuli (CS + s) were paired with shock and the third was not. During extinction, we held constant the amount of direct, non-reinforced, exposure to the CSs (i.e. direct extinction), and critically varied whether another individual-acting as a demonstrator-experienced safety (CS + vic safety) or aversive reinforcement (CS + vic reinf). During extinction, ventromedial prefrontal cortex (vmPFC) responses to the CS + vic reinf increased but decreased to the CS + vic safety This pattern of vmPFC activity was reversed during a subsequent fear reinstatement test, suggesting a temporal shift in the involvement of the vmPFC. Moreover, only the CS + vic reinf association recovered. Our data suggest that vicarious extinction prevents the return of conditioned fear responses, and that this efficacy is reflected by diminished vmPFC involvement during extinction learning. The present findings may have important implications for understanding how social information influences the persistence of fear memories in individuals suffering from emotional disorders. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  16. Selection, subdivision and extinction and recolonization.

    Science.gov (United States)

    Cherry, Joshua L

    2004-02-01

    In a subdivided population, the interaction between natural selection and stochastic change in allele frequency is affected by the occurrence of local extinction and subsequent recolonization. The relative importance of selection can be diminished by this additional source of stochastic change in allele frequency. Results are presented for subdivided populations with extinction and recolonization where there is more than one founding allele after extinction, where these may tend to come from the same source deme, where the number of founding alleles is variable or the founders make unequal contributions, and where there is dominance for fitness or local frequency dependence. The behavior of a selected allele in a subdivided population is in all these situations approximately the same as that of an allele with different selection parameters in an unstructured population with a different size. The magnitude of the quantity N(e)s(e), which determines fixation probability in the case of genic selection, is always decreased by extinction and recolonization, so that deleterious alleles are more likely to fix and advantageous alleles less likely to do so. The importance of dominance or frequency dependence is also altered by extinction and recolonization. Computer simulations confirm that the theoretical predictions of both fixation probabilities and mean times to fixation are good approximations.

  17. Mass Extinctions and Biosphere-Geosphere Stability

    Science.gov (United States)

    Rothman, Daniel; Bowring, Samuel

    2015-04-01

    Five times in the past 500 million years, mass extinctions have resulted in the loss of greater than three-fourths of living species. Each of these events is associated with significant environmental change recorded in the carbon-isotopic composition of sedimentary rocks. There are also many such environmental events in the geologic record that are not associated with mass extinctions. What makes them different? Two factors appear important: the size of the environmental perturbation, and the time scale over which it occurs. We show that the natural perturbations of Earth's carbon cycle during the past 500 million years exhibit a characteristic rate of change over two orders of magnitude in time scale. This characteristic rate is consistent with the maximum rate that limits quasistatic (i.e., near steady-state) evolution of the carbon cycle. We identify this rate with marginal stability, and show that mass extinctions occur on the fast, unstable side of the stability boundary. These results suggest that the great extinction events of the geologic past, and potentially a "sixth extinction" associated with modern environmental change, are characterized by common mechanisms of instability.

  18. Quantitative analysis of forest fire extinction efficiency

    Directory of Open Access Journals (Sweden)

    Miguel E. Castillo-Soto

    2015-08-01

    Full Text Available Aim of study: Evaluate the economic extinction efficiency of forest fires, based on the study of fire combat undertaken by aerial and terrestrial means. Area of study, materials and methods: Approximately 112,000 hectares in Chile. Records of 5,876 forest fires that occurred between 1998 and 2009 were analyzed. The area further provides a validation sector for results, by incorporating databases for the years 2010 and 2012. The criteria used for measuring extinction efficiency were economic value of forestry resources, Contraction Factor analysis and definition of the extinction costs function. Main results: It is possible to establish a relationship between burnt area, extinction costs and economic losses. The method proposed may be used and adapted to other fire situations, requiring unit costs for aerial and terrestrial operations, economic value of the property to be protected and speed attributes of fire spread in free advance. Research highlights: The determination of extinction efficiency in containment works of forest fires and potential projection of losses, different types of plant fuel and local conditions favoring the spread of fire broaden the admissible ranges of a, φ and Ce considerably.

  19. Turbulent jet in confined counterflow

    Indian Academy of Sciences (India)

    The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct limit of ...

  20. Elucidating Jet Energy Loss Using Jets Prospects from ATLAS

    CERN Document Server

    Grau, N

    2009-01-01

    Jets at the LHC are expected to provide the testing ground for studying QCD energy loss. In this contribution, we briefly outline the strategy that will be used to measure jets in ATLAS and how we will go about studying energy loss. We describe the utility of measuring the jet $R_{AA}$, the fragmentation function, and heavy flavor jets. Utilizing the collision energy provided by the LHC and the nearly hermetic and highly segmented calorimeter, ATLAS is expected to make important contributions to the understanding of parton energy loss using fully reconstructed jets.

  1. Elucidating Jet Energy Loss Using Jets: Prospects from ATLAS

    International Nuclear Information System (INIS)

    Grau, N.

    2009-01-01

    Jets at the LHC are expected to provide the testing ground for studying QCD energy loss. In this contribution, we briefly outline the strategy that will be used to measure jets in ATLAS and how we will go about studying energy loss. We describe the utility of measuring the jet R AA , the fragmentation function, and heavy flavor jets. Utilizing the collision energy provided by the LHC and the nearly hermetic and highly segmented calorimeter, ATLAS is expected to make important contributions to the understanding of parton energy loss using fully reconstructed jets.

  2. JET joint undertaking

    International Nuclear Information System (INIS)

    1984-06-01

    JET began operations on 25 June 1983. This annual report contains administrative information and a general review of scientific and technical developments. Among them are vacuum systems, toroidal and poloidal field systems, power supplies, neutral beam heating, radiofrequency heating, remote handling, tritium handling, control and data acquisition systems and diagnostic systems

  3. Triton burnup in JET

    International Nuclear Information System (INIS)

    Chipsham, E.; Jarvis, O.N.; Sadler, G.

    1989-01-01

    Triton burnup measurements have been made at JET using time-integrated copper activation and time-resolved silicon detector techniques. The results confirm the classical nature of both the confinement and the slowing down of the 1 MeV tritons in a plasma. (author) 8 refs., 3 figs

  4. Vortex diode jet

    Science.gov (United States)

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  5. Jets in Active Galaxies

    Indian Academy of Sciences (India)

    which are rapidly rotating neutron stars emitting narrow beams of radiation. Images of ... rized into starburst galaxies and AGN powered by SMBHs. The ..... swer lies in the relativistic motion of the jets which boosts the flux density of .... radio cores, detection of ... to as synchrotron self-Compton or SSC, or those of the cosmic.

  6. LHCb jet reconstruction

    International Nuclear Information System (INIS)

    Francisco, Oscar; Rangel, Murilo; Barter, William; Bursche, Albert; Potterat, Cedric; Coco, Victor

    2012-01-01

    Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10 32 cm -2 s -1 and the integrated luminosity reached the value of 1,02fb -1 on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space ηX φ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its η region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

  7. LHCb jet reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Francisco, Oscar; Rangel, Murilo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Barter, William [University of Cambridge, Cambridge (United Kingdom); Bursche, Albert [Universitat Zurich, Zurich (Switzerland); Potterat, Cedric [Universitat de Barcelona, Barcelona (Spain); Coco, Victor [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands)

    2012-07-01

    Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10{sup 32} cm{sup -2}s{sup -1} and the integrated luminosity reached the value of 1,02fb{sup -1} on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space {eta}X {phi} and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its {eta} region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

  8. Fastener investigation in JET

    Energy Technology Data Exchange (ETDEWEB)

    Bunting, P., E-mail: patrick.bunting@ccfe.ac.uk; Thompson, V.; Riccardo, V.

    2016-11-15

    Highlights: • Experimental work to identify the cause of a bolt seizure inside the JET vessel. • Taguchi method used to reduce tests to 16 while covering 5 parameters. • Experimental work was unable to reproduce bolt seizure. • Thread contamination had little effect on the bolt performance. - Abstract: JET is an experimental fusion reactor consisting of magnetically confined, high temperature plasma inside a large ultra-high vacuum chamber. The inside of the chamber is protected from the hot plasma with tiles made from beryllium, tungsten, carbon composites and other materials bolted to the vessel wall. The study was carried out in response to a JET fastener seizing inside the vacuum vessel. The following study looks at characterising the magnitude of the individual factors affecting the fastener break away torque. This was carried out using a statistical approach, the Taguchi method: isolating the net effect of individual factors present in a series of tests [1](Grove and Davis, 1992). Given the severe environment within the JET vessel due to the combination of heat, ultra-high vacuum and the high contact pressure in bolt threads, the contributions of localised diffusion bonding is assessed in conjunction with various combinations of bolt and insert material.

  9. Jet Inlet Efficiency

    Science.gov (United States)

    2013-08-08

    AFRL-RW-EG-TR-2014-044 Jet Inlet Efficiency Nigel Plumb Taylor Sykes-Green Keith Williams John Wohleber Munitions Aerodynamics Sciences...CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) Nigel Plumb Taylor Sykes-Green Keith Williams John

  10. Abrasive water jet cutting

    International Nuclear Information System (INIS)

    Leist, K.J.; Funnell, G.J.

    1988-01-01

    In the process of selecting a failed equipment cut-up tool for the process facility modifications (PFM) project, a system using an abrasive water jet (AWJ) was developed and tested for remote disassembly of failed equipment. It is presented in this paper

  11. Jet-images: computer vision inspired techniques for jet tagging

    Energy Technology Data Exchange (ETDEWEB)

    Cogan, Josh; Kagan, Michael; Strauss, Emanuel; Schwarztman, Ariel [SLAC National Accelerator Laboratory,Menlo Park, CA 94028 (United States)

    2015-02-18

    We introduce a novel approach to jet tagging and classification through the use of techniques inspired by computer vision. Drawing parallels to the problem of facial recognition in images, we define a jet-image using calorimeter towers as the elements of the image and establish jet-image preprocessing methods. For the jet-image processing step, we develop a discriminant for classifying the jet-images derived using Fisher discriminant analysis. The effectiveness of the technique is shown within the context of identifying boosted hadronic W boson decays with respect to a background of quark- and gluon-initiated jets. Using Monte Carlo simulation, we demonstrate that the performance of this technique introduces additional discriminating power over other substructure approaches, and gives significant insight into the internal structure of jets.

  12. Jet-images: computer vision inspired techniques for jet tagging

    International Nuclear Information System (INIS)

    Cogan, Josh; Kagan, Michael; Strauss, Emanuel; Schwarztman, Ariel

    2015-01-01

    We introduce a novel approach to jet tagging and classification through the use of techniques inspired by computer vision. Drawing parallels to the problem of facial recognition in images, we define a jet-image using calorimeter towers as the elements of the image and establish jet-image preprocessing methods. For the jet-image processing step, we develop a discriminant for classifying the jet-images derived using Fisher discriminant analysis. The effectiveness of the technique is shown within the context of identifying boosted hadronic W boson decays with respect to a background of quark- and gluon-initiated jets. Using Monte Carlo simulation, we demonstrate that the performance of this technique introduces additional discriminating power over other substructure approaches, and gives significant insight into the internal structure of jets.

  13. Extinction times of epidemic outbreaks in networks.

    Science.gov (United States)

    Holme, Petter

    2013-01-01

    In the Susceptible-Infectious-Recovered (SIR) model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

  14. Astrophysical life extinctions what killed the dinosaurs?

    CERN Document Server

    Dar, Arnon

    1999-01-01

    Geological records indicate that the exponential diversification of marine and continental life on Earth in the past 500 My was interrupted by many life extinctions. They also indicate that the major mass extinctions were correlated in time with large meteoritic impacts, gigantic volcanic eruptions, sea regressions and drastic changes in global climate. Some of these catastrophes coincided in time. The astrophysical life extinction mechanisms which were proposed so far, in particular, meteoritic impacts, nearby supernova explosions, passage through molecular or dark matter clouds, and Galactic gamma/cosmic ray bursts cannot explain the time coincidences between these catastrophes. However, recent observations suggest that many planetary-mass objects may be present in the outer solar system between the Kuiper belt and the Oort cloud. Gravitational perturbations may occasionally bring them into the inner solar system. Their passage near Earth could have generated gigantic tidal waves, large volcanic eruptions, ...

  15. Biotic extinctions by solar flares; and reply

    International Nuclear Information System (INIS)

    Beland, P.; Russell, D.A.; Crutzen, P.J.; Reid, G.C.

    1976-01-01

    Some comments are offered on the paper by Reid and others (nature 259:177 (1976)) in which a mechanism was suggested by which solar protons might catastrophically deplete atmospheric D 3 during a reversal of the Earth's geomagnetic field. Organisms would thereby be exposed to a more intense UV environment, leading to species extinctions. These authors assumed that during a reversal the geomagnetic field effectively disappears for about 1000 years, and also that solar flares sufficiently intense to cause extinctions occur at intervals of 1000 years or more. The validity of these assumptions is here examined using data on geomagnetic reversals identified over the past 75 M years, together with extinction data, and some anomalies are pointed out. A reply by Reid and others is appended. (U.K.)

  16. The fossil record of the sixth extinction.

    Science.gov (United States)

    Plotnick, Roy E; Smith, Felisa A; Lyons, S Kathleen

    2016-05-01

    Comparing the magnitude of the current biodiversity crisis with those in the fossil record is difficult without an understanding of differential preservation. Integrating data from palaeontological databases with information on IUCN status, ecology and life history characteristics of contemporary mammals, we demonstrate that only a small and biased fraction of threatened species (fossil record, compared with 20% of non-threatened species. We find strong taphonomic biases related to body size and geographic range. Modern species with a fossil record tend to be large and widespread and were described in the 19(th) century. The expected magnitude of the current extinction based only on species with a fossil record is about half of that of one based on all modern species; values for genera are similar. The record of ancient extinctions may be similarly biased, with many species having originated and gone extinct without leaving a tangible record. © 2016 John Wiley & Sons Ltd/CNRS.

  17. Extinction times of epidemic outbreaks in networks.

    Directory of Open Access Journals (Sweden)

    Petter Holme

    Full Text Available In the Susceptible-Infectious-Recovered (SIR model of disease spreading, the time to extinction of the epidemics happens at an intermediate value of the per-contact transmission probability. Too contagious infections burn out fast in the population. Infections that are not contagious enough die out before they spread to a large fraction of people. We characterize how the maximal extinction time in SIR simulations on networks depend on the network structure. For example we find that the average distances in isolated components, weighted by the component size, is a good predictor of the maximal time to extinction. Furthermore, the transmission probability giving the longest outbreaks is larger than, but otherwise seemingly independent of, the epidemic threshold.

  18. Mammal extinctions, body size, and paleotemperature.

    Science.gov (United States)

    Bown, T M; Holroyd, P A; Rose, K D

    1994-10-25

    There is a general inverse relationship between the natural logarithm of tooth area (a body size indicator) of some fossil mammals and paleotemperature during approximately 2.9 million years of the early Eocene in the Bighorn Basin of northwest Wyoming. When mean temperatures became warmer, tooth areas tended to become smaller. During colder times, larger species predominated; these generally became larger or remained the same size. Paleotemperature trends also markedly affected patterns of local (and, perhaps, regional) extinction and immigration. New species appeared as immigrants during or near the hottest (smaller forms) and coldest (larger forms) intervals. Paleotemperature trend reversals commonly resulted in the ultimate extinction of both small forms (during cooling intervals) and larger forms (during warming intervals). These immigrations and extinctions mark faunal turnovers that were also modulated by sharp increases in sediment accumulation rate.

  19. A new method for fluid input into a hybrid synthetic jet actuator

    Directory of Open Access Journals (Sweden)

    Kordík J.

    2014-03-01

    Full Text Available A new principle of flow rectification for hybrid synthetic jet actuators is introduced in this paper. As is well known, the flow rectification can be best accomplished by means of fluidic diodes. Novelty of the present study are fluidic diodes with two mutually opposed nozzles. Interaction between the periodic jet flows from the nozzles causes a difference between the blowing and suction strokes, resulting in a particularly efficient rectification effect. The distance between the nozzle exits as well as the oscillation frequency were the parameters, which were varied during hot-wire measurements. The combination of those parameters achieving the highest volumetric effciency was identified.

  20. Jet substructure using semi-inclusive jet functions in SCET

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Zhong-Bo [Theoretical Division, Los Alamos National Laboratory,Los Alamos, NM 87545 (United States); Department of Physics and Astronomy, University of California,Los Angeles, CA 90095 (United States); Ringer, Felix; Vitev, Ivan [Theoretical Division, Los Alamos National Laboratory,Los Alamos, NM 87545 (United States)

    2016-11-25

    We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron h is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function G{sub i}{sup h}(z=ω{sub J}/ω,z{sub h}=ω{sub h}/ω{sub J},ω{sub J},R,μ), which depends on the jet radius R and the large light-cone momenta of the parton ‘i’ initiating the jet (ω), the jet (ω{sub J}), and the hadron h (ω{sub h}). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function G{sub i}{sup h}(z,z{sub h},ω{sub J},R,μ) are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter R up to next-to-leading logarithmic (NLL{sub R}) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL{sub R} results for the hadron distribution inside the jet. We present numerical results for pp→(jet h)X in the new framework, and find excellent agreement with existing LHC experimental data.

  1. Jet substructure using semi-inclusive jet functions in SCET

    International Nuclear Information System (INIS)

    Kang, Zhong-Bo; Ringer, Felix; Vitev, Ivan

    2016-01-01

    We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron h is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function G_i"h(z=ω_J/ω,z_h=ω_h/ω_J,ω_J,R,μ), which depends on the jet radius R and the large light-cone momenta of the parton ‘i’ initiating the jet (ω), the jet (ω_J), and the hadron h (ω_h). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function G_i"h(z,z_h,ω_J,R,μ) are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter R up to next-to-leading logarithmic (NLL_R) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL_R results for the hadron distribution inside the jet. We present numerical results for pp→(jet h)X in the new framework, and find excellent agreement with existing LHC experimental data.

  2. Deciphering jet quenching with JEWEL

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    In heavy ion collisions jets arising from the fragmentation of hard quarks and gluons experience strong modifications due to final state re-scattering. This so-called jet quenching is related to the emergence of collectivity and equilibration in QCD. I will give an introduction to jet quenching and its modeling in JEWEL, a Monte Carlo implementation of a dynamical model for jet quenching. I will then discuss examples highlighting how JEWEL can be used to elucidate the physical mechanisms relevant for jet quenching.  

  3. Interstellar extinction in the Taurus dark clouds

    International Nuclear Information System (INIS)

    Meistas, E.; Straizys, V.

    1981-01-01

    The results of photoelectric photometry of 89 stars in the Vilnius seven-color system in the area of the Taurus dark clouds with corrdinates (1950) 4sup(h)16sup(m)-4sup(h)33sup(m), +16 0 -+20 0 are presented. Photometric spectral types, absolute magnitude, color excesses, interstellar extinctions and distances of the stars are determined. The distance of the dark nebula is found to be 140 pc and is in a good agreement with the distance determined for the dark nebula Khavtassi 286, 278. The average extinction Asub(v) in the investigated area is of the order of 1.4. (author)

  4. Structure of pulsed plasma jets

    International Nuclear Information System (INIS)

    Cavolowsky, J.A.

    1987-01-01

    A pulsed plasma jet is a turbulent, inhomogeneous fluid mechanical discharge capable of initiating and enhancing combustion. Having shown the ability to ignite lean fuel mixtures, it now offers the potential for real-time control of combustion processes. This study explored the fluid-mechanical and chemical properties of such jets. The fluid-mechanical structure of the jet was examined using two optical diagnostic techniques. Self-light streak photography provided information on the motion of luminous gas particles in its core. It revealed that plasma jets behave either totally subsonic or embody a supersonic core. The turbulent, thermal evolution of the jet was explored using high-speed-laser schlieren cinematography. By examining plasma jet generators with both opaque and transparent plasma cavities, detailed information on plasma formation and jet structure, beginning with the electric arc discharge in the cavity, was obtained. These records revealed the production of thermal stratifications in the cavity that could account for the plasma particles in the jet core. After the electrical discharges ceased, the turbulent jet behaved as a self-similar plume. Molecular-beam mass spectrometry was used to determine temperature and species concentration in the jet. Both non-combustible and combustible jets were studied

  5. Performance Enhancement of a Vertical Tail Using Synthetic Jet Actuators

    Science.gov (United States)

    Rathay, Nicholas

    spanwise jet spacing. The Stereo PIV data also suggested that the outboard sides of the vortex rings were favorable for separation control, and the inboard sides might have had a detrimental effect. This provided a partial explanation to the effect of the orifices' skew angle, and indicated that separation could perhaps be more efficiently controlled by altering the weighted contribution of the two sides of the vortex rings. Scaling was briefly studied by comparing results obtained on the 1/19 th and 1/9th scale models. It was found that side force improvement for both models was similar when the orifices were scaled dimensionally (as opposed to non--dimensionally). Although it was not clear as to why, the data, in general, indicated that for the largest performance enhancement the area--based momentum that the synthetic jets generate should be maximized.

  6. Effect of steam condensation on pressure and temperature under hydrogen jet fire in a vented enclosure

    International Nuclear Information System (INIS)

    Kuznetsov, Mike; Xiao, Jianjun; Travis, Jack

    2017-01-01

    Hydrogen release through leaks due to the LOCA and MCCI accidents and its immediate ignition leads to formation of hydrogen jet fire in a containment of reactor building. An experimental study of hydrogen jet fire in a chamber of 1x1x1 m 3 volume with different vent position, vent areas from 1 to 90 cm 2 and hydrogen mass flow rates from 0.027 to 1.087 g/s were performed in current work. Depending on hydrogen mass flow rate and vent area a well-ventilated or under-ventilated jet fire regime may occur. In the case of relatively small hydrogen release rate and large vent area, relatively stable jet fire behaviour for well-ventilated jet fire leading to over-pressure not more than 0.8 mbar was found. Three different scenarios of under-ventilated jet fire behaviour with self-extinction, re-ignition and external flame leading to relatively high overpressure of 10-100 mbar were found experimentally and numerically. Numerical simulations with GASFLOW-MPI code were performed with/without modelling heat conduction in solid walls, steam condensation, convective heat transfer and thermal radiation. With heat transfer modelling, both initial pressure peak and pressure decay were very well predicted compared to the experimental data. Numerical simulations were then compared with experimental Background Oriented Schlieren (BOS) images obtained to visualize the hydrogen combustion process. Self-extinction and re-ignition events were captured in the numerical simulation as well. An adiabatic case indicates that heat transfer and steam condensation must be included into the combustion model to accurately predict the physical phenomena of turbulent hydrogen jet flames in a vented enclosure. (author)

  7. DeepJet: a deep-learned multiclass jet-tagger for slim and fat jets

    CERN Multimedia

    CERN. Geneva; Qu, Huilin; Stoye, Markus; Kieseler, Jan; Verzetti, Mauro

    2018-01-01

    We present a customized neural network architecture for both, slim and fat jet tagging. It is based on the idea to keep the concept of physics objects, like particle flow particles, as a core element of the network architecture. The deep learning algorithm works for most of the common jet classes, i.e. b, c, usd and gluon jets for slim jets and W, Z, H, QCD and top classes for fat jets. The developed architecture promising gains in performance as shown in simulation of the CMS collaboration. Currently the tagger is under test in real data in the CMS experiment.

  8. Laser Boost of a Small Interstellar Ram Jet to Obtain Operational Velocity. Implications for the DM Rocket/Ram Jet Model

    Science.gov (United States)

    Walcott Beckwith, Andrew

    2010-05-01

    In other conference research papers, Beckwith obtained a maximum DM mass/energy value of up to 5 TeV, as opposed to 400 GeV for DM, which may mean more convertible power for a dark matter ram jet. The consequences are from assuming that axions are CDM, and KK gravitons are for WDM, then ρWarm-Dark-Matter would dominate not only structure formation in early universe formation, but would also influence the viability of the DM ram jet applications for interstellar travel. The increase in convertible DM mass makes the ram jet a conceivable option. This paper in addition to describing the scientific issues leading to that 5 TeV mass for DM also what are necessary and sufficient laser boost systems which would permit a ram net to become operational.

  9. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    Energy Technology Data Exchange (ETDEWEB)

    Peek, J. E. G.; Schiminovich, David, E-mail: jegpeek@gmail.com [Department of Astronomy, Columbia University, New York, NY (United States)

    2013-07-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  10. The Neandertal extinction in eastern Central Europe

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří

    2005-01-01

    Roč. 137, - (2005), s. 69-75 ISSN 1040-6182 Institutional research plan: CEZ:AV0Z80010507 Keywords : Central Europe Neandertals * early modern humans * extinction Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.210, year: 2005

  11. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    International Nuclear Information System (INIS)

    Peek, J. E. G.; Schiminovich, David

    2013-01-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is ∼10% and ∼35% higher than expected, with significant variation across the sky. We find that no single R V parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  12. Interstellar Extinction in the Gaia Photometric Systems

    Directory of Open Access Journals (Sweden)

    Bridžius A.

    2003-12-01

    Full Text Available Three medium-band photometric systems proposed for the Gaia space mission are intercompared in determining color excesses for stars of spectral classes from O to M at V = 18 mag. A possibility of obtaining a three-dimensional map of the interstellar extinction is discussed.

  13. Optical atmospheric extinction over Cerro Paranal

    NARCIS (Netherlands)

    Patat, F.; Moehler, S.; O'Brien, K.; Pompei, E.; Bensby, T.; Carraro, G.; de Ugarte Postigo, A.; Fox, A.; Gavignaud, I.; James, G.; Korhonen, H.; Ledoux, C.; Randall, S.; Sana, H.A.A.; Smoker, J.; Stefl, S.; Szeifert, T.

    2011-01-01

    Aims. The present study was conducted to determine the optical extinction curve for Cerro Paranal under typical clear-sky observing conditions, with the purpose of providing the community with a function to be used to correct the observed spectra, with an accuracy of 0.01 mag airmass-1.

  14. A new explanation of the extinction paradox

    International Nuclear Information System (INIS)

    Berg, M.J.; Sorensen, C.M.; Chakrabarti, A.

    2011-01-01

    This work presents a new explanation for the extinction paradox and shows that the canonical explanations are incorrect. This paradox refers to the large size limit of a particle's extinction cross section. It is called a paradox because the geometrical optics approximation, which should be valid in this limit, predicts a cross section that is half of the true value. The new explanation is achieved by formulating the scattered wave in terms of an integral over the particle's surface where the seemingly unrelated Ewald-Oseen theorem appears in the formulation. By expressing the cross section in terms of this surface integral, the Ewald-Oseen theorem is analytically connected to the cross section. Several illustrations are used to reveal the significance of this connection: The paradox is seen to be a consequence of the requirement that the incident wave be canceled within the particle by secondary radiation from its own internal field. Following this, the canonical explanations are examined to reveal serious problems. In the process, the same asymptotic extinction behavior is shown to occur for small highly refractive dielectric particles, and thus is not just a large particle size or small wavelength effect as is often stated. The traditional explanations cannot account for this behavior while the new one actually predicts it. All in all, this work constitutes a fundamental reworking of 60 years of accepted understanding for the cause of the asymptotic behavior of the extinction cross section.

  15. Time to extinction of bird populations

    NARCIS (Netherlands)

    Sæther, B-E.; Engen, S.; Møller, A.P.; Visser, M.E.; Matthysen, E.; Fiedler, W.; Lambrechts, M.M.; Becker, P.H.; Brommer, J.E.; Dickinson, J.; du Feu, C.; Gehlbach, F.R.; Merilä, J.; Rendell, W.; Robertson, R.J.; Thomson, D.L.; Török, J.

    2005-01-01

    The risk of extinction of populations has not previously been empirically related to parameters characterizing their population dynamics. To analyze this relationship, we simulated how the distribution of population dynamical characters changed as a function of time, in both the remaining and the

  16. Methylphenidate Enhances Extinction of Contextual Fear

    Science.gov (United States)

    Abraham, Antony D.; Cunningham, Christopher L.; Lattal, K. Matthew

    2012-01-01

    Methylphenidate (MPH, Ritalin) is a norepinephrine and dopamine transporter blocker that is widely used in humans for treatment of attention deficit disorder and narcolepsy. Although there is some evidence that targeted microinjections of MPH may enhance fear acquisition, little is known about the effect of MPH on fear extinction. Here, we show…

  17. Dust extinction in the first galaxies

    Science.gov (United States)

    Jaacks, Jason; Finkelstein, Steven L.; Bromm, Volker

    2018-04-01

    Using cosmological volume simulations and a custom built sub-grid model for Population III (Pop III) star formation, we examine the baseline dust extinction in the first galaxies due to Pop III metal enrichment in the first billion years of cosmic history. We find that although the most enriched, high-density lines of sight in primordial galaxies can experience a measurable amount of extinction from Pop III dust [E(B - V)max = 0.07, AV, max ≈ 0.28], the average extinction is very low with ≲ 10-3. We derive a power-law relationship between dark matter halo mass and extinction of E(B-V)∝ M_halo^{0.80}. Performing a Monte Carlo parameter study, we establish the baseline reddening of the ultraviolet spectra of dwarf galaxies at high redshift due to Pop III enrichment only. With this method, we find - 2.51 ± 0.07, which is both nearly halo mass and redshift independent.

  18. Stressor controllability modulates fear extinction in humans

    Science.gov (United States)

    Hartley, Catherine A.; Gorun, Alyson; Reddan, Marianne C.; Ramirez, Franchesca; Phelps, Elizabeth A.

    2014-01-01

    Traumatic events are proposed to play a role in the development of anxiety disorders, however not all individuals exposed to extreme stress experience a pathological increase in fear. Recent studies in animal models suggest that the degree to which one is able to control an aversive experience is a critical factor determining its behavioral consequences. In this study, we examined whether stressor controllability modulates subsequent conditioned fear expression in humans. Participants were randomly assigned to an escapable stressor condition, a yoked inescapable stressor condition, or a control condition involving no stress exposure. One week later, all participants underwent fear conditioning, fear extinction, and a test of extinction retrieval the following day. Participants exposed to inescapable stress showed impaired fear extinction learning and increased fear expression the following day. In contrast, escapable stress improved fear extinction and prevented the spontaneous recovery of fear. Consistent with the bidirectional controllability effects previously reported in animal models, these results suggest that one's degree of control over aversive experiences may be an important factor influencing the development of psychological resilience or vulnerability in humans. PMID:24333646

  19. Biological hierarchies and the nature of extinction.

    Science.gov (United States)

    Congreve, Curtis R; Falk, Amanda R; Lamsdell, James C

    2018-05-01

    Hierarchy theory recognises that ecological and evolutionary units occur in a nested and interconnected hierarchical system, with cascading effects occurring between hierarchical levels. Different biological disciplines have routinely come into conflict over the primacy of different forcing mechanisms behind evolutionary and ecological change. These disconnects arise partly from differences in perspective (with some researchers favouring ecological forcing mechanisms while others favour developmental/historical mechanisms), as well as differences in the temporal framework in which workers operate. In particular, long-term palaeontological data often show that large-scale (macro) patterns of evolution are predominantly dictated by shifts in the abiotic environment, while short-term (micro) modern biological studies stress the importance of biotic interactions. We propose that thinking about ecological and evolutionary interactions in a hierarchical framework is a fruitful way to resolve these conflicts. Hierarchy theory suggests that changes occurring at lower hierarchical levels can have unexpected, complex effects at higher scales due to emergent interactions between simple systems. In this way, patterns occurring on short- and long-term time scales are equally valid, as changes that are driven from lower levels will manifest in different forms at higher levels. We propose that the dual hierarchy framework fits well with our current understanding of evolutionary and ecological theory. Furthermore, we describe how this framework can be used to understand major extinction events better. Multi-generational attritional loss of reproductive fitness (MALF) has recently been proposed as the primary mechanism behind extinction events, whereby extinction is explainable solely through processes that result in extirpation of populations through a shutdown of reproduction. While not necessarily explicit, the push to explain extinction through solely population-level dynamics

  20. Jet photoproduction at HERA

    International Nuclear Information System (INIS)

    Frixione, S.

    1997-01-01

    We compute various kinematical distributions for one-jet and two-jet inclusive photoproduction at HERA. Our results are accurate to next-to-leading order in QCD. We use the subtraction method for the cancellation of infrared singularities. We perform a thorough study of the reliability of QCD predictions; in particular, we consider the scale dependence of our results and discuss the cases when the perturbative expansion might break down. We also deal with the problem of the experimental definition of the pointlike and hadronic components of the incident photon, and briefly discuss the sensitivity of QCD predictions upon the input parameters of the calculation, like α S and the parton densities. (orig.)

  1. Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction

    DEFF Research Database (Denmark)

    Finnegan, Seth; Mac Ørum Rasmussen, Christian; Harper, David A. T.

    2016-01-01

    –Early Silurian genus extinctions and evaluate which extinction drivers are best supported by the data. The first (latest Katian) pulse of the LOME preferentially affected genera restricted to deeper waters or to relatively narrow (less than 35°) palaeolatitudinal ranges. This pattern is only observed...... in the latest Katian, suggesting that it reflects drivers unique to this interval. Extinction of exclusively deeper-water genera implies that changes in water mass properties such as dissolved oxygen content played an important role. Extinction of genera with narrow latitudinal ranges suggests that interactions...... between shifting climate zones and palaeobiogeography may also have been important. We test the latter hypothesis by estimating whether each genus would have been able to track habitats within its thermal tolerance range during the greenhouse–icehouse climate transition. Models including these estimates...

  2. QCD and jets

    International Nuclear Information System (INIS)

    Munehisa, Tomo

    1990-01-01

    We present a review on the parton shower in e + e - annihilation. Also we discuss the next-to-leading-logarithmic parton shower. We emphasize that this new model provides a useful tool for the determinations of Λ MS from jet distributions. Analysis by the new model gives us Λ MS = 0.235±0.052 GeV from data of PETRA, PEP and TRISTAN. (author)

  3. Active control of continuous air jet with bifurcated synthetic jets

    Directory of Open Access Journals (Sweden)

    Dančová Petra

    2017-01-01

    Full Text Available The synthetic jets (SJs have many significant applications and the number of applications is increasing all the time. In this research the main focus is on the primary flow control which can be used effectively for the heat transfer increasing. This paper deals with the experimental research of the effect of two SJs worked in the bifurcated mode used for control of an axisymmetric air jet. First, the control synthetic jets were measured alone. After an adjustment, the primary axisymmetric jet was added in to the system. For comparison, the primary flow without synthetic jets control was also measured. All experiments were performed using PIV method whereby the synchronization between synthetic jets and PIV system was necessary to do.

  4. Endangered Species and Natural Resource Exploitation: Extinction vs. Coexistence

    OpenAIRE

    Tsur, Yacov; Zemel, Amos

    1994-01-01

    The threat on the survival of animal species due to intensive use of natural resources is incorporated within resource management models, paying special attention to uncertainty regarding the conditions that lead to extinction. The manner in which the potential benefits forgone due to the species extinction (denoted extinction penalty) induce more conservative exploitation policies is studied in detail. When the extinction penalty is ignored, the optimal policy is to drive the resource stock ...

  5. Extinction models for cancer stem cell therapy

    Science.gov (United States)

    Sehl, Mary; Zhou, Hua; Sinsheimer, Janet S.; Lange, Kenneth L.

    2012-01-01

    Cells with stem cell-like properties are now viewed as initiating and sustaining many cancers. This suggests that cancer can be cured by driving these cancer stem cells to extinction. The problem with this strategy is that ordinary stem cells are apt to be killed in the process. This paper sets bounds on the killing differential (difference between death rates of cancer stem cells and normal stem cells) that must exist for the survival of an adequate number of normal stem cells. Our main tools are birth–death Markov chains in continuous time. In this framework, we investigate the extinction times of cancer stem cells and normal stem cells. Application of extreme value theory from mathematical statistics yields an accurate asymptotic distribution and corresponding moments for both extinction times. We compare these distributions for the two cell populations as a function of the killing rates. Perhaps a more telling comparison involves the number of normal stem cells NH at the extinction time of the cancer stem cells. Conditioning on the asymptotic time to extinction of the cancer stem cells allows us to calculate the asymptotic mean and variance of NH. The full distribution of NH can be retrieved by the finite Fourier transform and, in some parameter regimes, by an eigenfunction expansion. Finally, we discuss the impact of quiescence (the resting state) on stem cell dynamics. Quiescence can act as a sanctuary for cancer stem cells and imperils the proposed therapy. We approach the complication of quiescence via multitype branching process models and stochastic simulation. Improvements to the τ-leaping method of stochastic simulation make it a versatile tool in this context. We conclude that the proposed therapy must target quiescent cancer stem cells as well as actively dividing cancer stem cells. The current cancer models demonstrate the virtue of attacking the same quantitative questions from a variety of modeling, mathematical, and computational perspectives

  6. Jet operated heat pump

    International Nuclear Information System (INIS)

    Collard, T.H.

    1982-01-01

    A jet pump system is shown that utilizes waste heat to provide heating and/or cooling. Waste heat diverted through a boiler causes a refrigerant to evaporate and expand for supersonic discharge through a nozzle thereby creating a vacuum in an evaporator coil. The vacuum draws the refrigerant in a gaseous state into a condensing section of a jet pump along with refrigerant from a reservoir in a subcooled liquid form. This causes condensation of the gas in a condensation section of the jet pump, while moving at constant velocity. The change in momentum of the fluid overcomes the system high side pressure. Some of the condensate is cooled by a subcooler. Refrigerant in a subcooled liquid state from the subcooler is fed back into the evaporator and the condensing section with an adequate supply being insured by the reservoir. The motive portion of the condensate is returned to the boiler sans subcooling. By proper valving start-up is insured, as well as the ability to switch from heating to cooling

  7. Greenland plateau jets

    Directory of Open Access Journals (Sweden)

    George William Kent Moore

    2013-08-01

    Full Text Available The high ice-covered topography of Greenland represents a significant barrier to atmospheric flow and, as a direct and indirect result, it plays a crucial role in the coupled climate system. The wind field over Greenland is important in diagnosing regional weather and climate, thereby providing information on the mass balance of the ice sheet as well as assisting in the interpretation of ice core data. Here, we identify a number of hitherto unrecognised features of the three-dimensional wind field over Greenland; including a 2500-km-long jet along the central ice sheet's western margin that extends from the surface into the middle-troposphere, as well as a similar but smaller scale and less intense feature along its eastern margin. We refer to these features as Greenland Plateau Jets. The jets are coupled to the downslope katabatic flow and we argue that they are maintained by the zonal temperature gradients associated with the strong temperature inversion over the central ice sheet. Their importance for Greenland's regional climate is discussed.

  8. Malthusian Catastrophe: Species Extinction Caused By Oversized Population

    OpenAIRE

    Pan, Xubin

    2017-01-01

    There is one pseudo-extinction debt and four occurring conditions for real extinction debt. Since small and oversized populations have a high extinction risk, Pan threshold (upper limit) was calculated for Verhulst-Pear logistic growth model and logistic model with the Allee effect, an important parameter corresponding to Allee threshold (lower limit).

  9. Fibroblast Growth Factor-2 Alters the Nature of Extinction

    Science.gov (United States)

    Graham, Bronwyn M.; Richardson, Rick

    2011-01-01

    These experiments examined the effects of the NMDA-receptor (NMDAr) antagonist MK801 on reacquisition and re-extinction of a conditioned fear that had been previously extinguished before injection of fibroblast growth factor-2 (FGF2) or vehicle. Recent findings have shown that relearning and re-extinction, unlike initial learning and extinction,…

  10. Inhibition of Estradiol Synthesis Impairs Fear Extinction in Male Rats

    Science.gov (United States)

    Graham, Bronwyn M.; Milad, Mohammed R.

    2014-01-01

    Emerging research has demonstrated that the sex hormone estradiol regulates fear extinction in female rodents and women. Estradiol may also regulate fear extinction in males, given its role in synaptic plasticity in both sexes. Here we report that inhibition of estradiol synthesis during extinction training, via the aromatase inhibitor fadrozole,…

  11. Slower Reacquisition after Partial Extinction in Human Contingency Learning

    Science.gov (United States)

    Morís, Joaquín; Barberia, Itxaso; Vadillo, Miguel A.; Andrades, Ainhoa; López, Francisco J.

    2017-01-01

    Extinction is a very relevant learning phenomenon from a theoretical and applied point of view. One of its most relevant features is that relapse phenomena often take place once the extinction training has been completed. Accordingly, as extinction-based therapies constitute the most widespread empirically validated treatment of anxiety disorders,…

  12. A study of the fundamental characteristics of 2175A extinction

    Science.gov (United States)

    Cardelli, Jason A.; Savage, Blair D.

    1987-01-01

    The characteristics of interstellar extinction were studied in the region of the 2175 A feature for lines of sight which appear to exhibit unusually weak ultraviolet extinction. The analysis was based upon a parameterization of the observed extinction via fitting specific mathematical functions in order to determine the position and width of the 2175 A feature. The data are currently being analyzed.

  13. Selecting for extinction: nonrandom disease-associated extinction homogenizes amphibian biotas.

    Science.gov (United States)

    Smith, Kevin G; Lips, Karen R; Chase, Jonathan M

    2009-10-01

    Studying the patterns in which local extinctions occur is critical to understanding how extinctions affect biodiversity at local, regional and global spatial scales. To understand the importance of patterns of extinction at a regional spatial scale, we use data from extirpations associated with a widespread pathogenic agent of amphibian decline, Batrachochytrium dendrobatidis (Bd) as a model system. We apply novel null model analyses to these data to determine whether recent extirpations associated with Bd have resulted in selective extinction and homogenization of diverse tropical American amphibian biotas. We find that Bd-associated extinctions in this region were nonrandom and disproportionately, but not exclusively, affected low-occupancy and endemic species, resulting in homogenization of the remnant amphibian fauna. The pattern of extirpations also resulted in phylogenetic homogenization at the family level and ecological homogenization of reproductive mode and habitat association. Additionally, many more species were extirpated from the region than would be expected if extirpations occurred randomly. Our results indicate that amphibian declines in this region are an extinction filter, reducing regional amphibian biodiversity to highly similar relict assemblages and ultimately causing amplified biodiversity loss at regional and global scales.

  14. Multiple Jets at the LHC with High Energy Jets

    DEFF Research Database (Denmark)

    Andersen, Jeppe Rosenkrantz; Smillie, Jennifer M.

    2011-01-01

    We present a flexible Monte Carlo implementation of the perturbative framework of High Energy Jets, describing multi-jet events at hadron colliders. The description includes a resummation which ensures leading logarithmic accuracy for large invariant mass between jets, and is matched to tree......-level accuracy for multiplicities up to 4 jets. The resummation includes all-order hard corrections, which become important for increasing centre-of-mass energy of the hadronic collision. We discuss observables relevant for confronting the perturbative framework with 7 TeV data from the LHC, and the impact...

  15. Tip opening of premixed bunsen flames: Extinction with negative stretch and local Karlovitz number

    KAUST Repository

    Vu, Tranmanh

    2015-04-01

    The characteristics of tip openings in premixed bunsen flames have been studied experimentally by measuring OH radicals from laser-induced fluorescence and tip curvatures from chemiluminescent images. Results showed that the tip opening occurred at a constant equivalence ratio and was independent of the jet velocity in propane/air mixtures. The observation of a local extinction phenomenon of the negatively stretched flame due to the flame curvature could not be consistently explained based on flame stretch or the Karlovitz number, since they varied appreciably with the jet velocity. The concept of the local Karlovitz number (KaL) was introduced, which is defined as the ratio of the characteristic reaction time in the normal direction for a stretched flame to the characteristic flow time in the tangential direction for the stretched flame. The local Karlovitz number maintained a constant value under tip opening conditions, irrespective of the jet velocity. Tip opening occurred at a reasonably constant local Karlovitz number of about ~1.72 when the nitrogen dilution level in propane and n-butane fuels was varied.

  16. Jet target intense neutron source

    International Nuclear Information System (INIS)

    Meier, K.L.

    1977-01-01

    A jet target Intense Neutron Source (INS) is being built by the Los Alamos Scientific Laboratory with DOE/MFE funding in order to perform radiation damage experiments on materials to be used in fusion power reactors. The jet target can be either a supersonic or a subsonic jet. Each type has its particular advantages and disadvantages, and either of the jets can be placed inside the spherical blanket converter which will be used to simulate a fusion reactor neutron environment. Preliminary mock-up experiments with a 16-mA, 115 keV, H + ion beam on a nitrogen gas supersonic jet show no serious problems in the beam formation, transport, or jet interaction

  17. Identifying jet quantum numbers event by event

    International Nuclear Information System (INIS)

    Teper, M.J.

    1979-12-01

    A method is proposed to identify the parton that gives rise to any particular jet. The method improves with the number of particles in the jet, and should indicate which of the jets in a three jet event at PETRA is the gluon jet. (author)

  18. Dynamics of Newtonian annular jets

    International Nuclear Information System (INIS)

    Paul, D.D.

    1978-12-01

    The main objectives of this investigation are to identify the significant parameters affecting the dynamics of Newtonian annular jets, and to develop theoretical models for jet break-up and collapse. This study has been motivated by recent developments in laser-fusion reactor designs; one proposed cavity design involves the use of an annular lithium jet to protect the cavity wall from the pellet debris emanating from the microexplosion

  19. A Dialogic Vaccine to Bridge Opposing Cultural Viewpoints Based on Bakhtin's Views on Dialogue and Estrangement.

    Science.gov (United States)

    Tajima, Atsushi

    2017-09-01

    Today, we face global conflicts between opposing ideologies that may be described in terms of cultural viewpoints and value judgments. It is difficult for individuals to determine whether ideologies are right or wrong because each ideology has its own worldview and sense of justice. Psychologists have an urgent mission to defuse the likelihood of fatal clashes between opposing cultural perspectives (ideologies), and to propose paradigms for peaceful coexistence. This paper examines the series of papers (Oh, Integrative Psychological and Behavioral Science, 51, 2017; Sakakibara, Integrative Psychological and Behavioral Science, 51, 2017; Watanabe, Integrative Psychological & Behavioral Science, 51, 2017) contributed to this volume that investigate the effects of high school and university educational programs promoting productive dialogue aimed at bridging, or transcending, conflicting perspectives among Japanese, Chinese, and Korean students. Here, I have evaluated the capacity of these educational programs to coordinate opposing cultural ideologies using the framework of Bakhtin's theories of dialogue and estrangement. Bakhtin viewed discourse with others who had opposing viewpoints as an opportunity to learn to overcome the one-sidedness of ideology, which ensues from automatic value judgments made by each speaker according to their culture, and he affirmed the value of flexible attitudes toward opposing viewpoints. In this paper, I review Bakhtin's theories relating to communication in a context of different cultural viewpoints, assess the general values of the educational practices mentioned above, and propose new concepts for applying these methods to other educational fields in the future using Bakhtin's theoretical viewpoints.

  20. JHKL photometry of three Herbig-Haro jet sources and a nebulous T Tauri star

    International Nuclear Information System (INIS)

    Vrba, F.J.; Rydgren, A.E.; Zak, D.S.; Computer Sciences Corp., Baltimore, MD; Rensselaer Polytechnic Institute, Troy, NY)

    1985-01-01

    Infrared sources have been detected at the positions of the Herbig-Haro jet sources HH 30, DG Tau B, and Haro 6-5 B in the Taurus dark cloud complex. The colors of these Herbig-Haro jet sources in the 1-4 micron wavelength range are comparable to those of the dustiest T Tauri stars, while the K magnitudes corrected for likely interstellar extinction are actually somewhat fainter than those oftypical T Tauri stars in this region. These observations are consistent with the view that these Herbig-Haro jet sources are low-mass premain-sequence stars. The nebulous T Tauri star Haro 6-5 was also observed and found to show both a large infrared excess and an intrinsic-polarization of about 3 percent in visible light. Thus this star seems to resemble HL Tau and DG Tau, which have been suggested as examples of young stars with circumstellar disks. 17 references

  1. Photon + jets at D0

    Energy Technology Data Exchange (ETDEWEB)

    Sonnenschein, Lars; /RWTH Aachen U.

    2009-06-01

    Photon plus jet production has been studied by the D0 experiment in Run II of the Fermilab Tevatron Collider at a centre of mass energy of {radical}s = 1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavour jet cross sections and double parton interactions in photon plus three jet events are presented. They are based on integrated luminosities between 0.4 fb{sup -1} and 1.0 fb{sup -1}. The results are compared to perturbative QCD calculations in various approximations.

  2. Decline and local extinction of Fucales in French Riviera: the harbinger of future extinctions?

    Directory of Open Access Journals (Sweden)

    T. THIBAUT

    2014-03-01

    Full Text Available The French Riviera is one of the Mediterranean areas that has been longest and most thoroughly impacted by human activities. Fucales are long-lived, large-sized brown algae that constitute a good model for studying human impact on species diversity. We gathered all historical data (literature and herbarium vouchers, since the early 19th century, to reconstruct their distribution. The current distribution was established from a 7-year (2007-2013 survey of the 212-km shoreline (1/2 500 map, by means of boating, snorkelling and scuba diving. Overall, 18 taxa of Cystoseira and Sargassum have been reported. Upon comparison with historical data, 5 taxa were no longer observed (C. elegans, C. foeniculacea f. latiramosa, C. squarrosa, C. spinosa var. spinosa and S. hornschuchii while C. jabukae, previously unrecorded, was observed. In addition to these  taxa, probably extinct at a local scale, some taxa had suffered a dramatic decline (C. barbata f. barbata, C. crinita, C. spinosa var. compressa and S. acinarium or become nearly extinct (C. foeniculacea f. tenuiramosa. Three of them, which played in the past significant functional roles in coastal communities, can be considered as functionally extinct. Possible causes of decline and local extinction are discussed. A similar situation has already been reported, although at a much more local scale, in a variety of Mediterranean localities. The question therefore arises about the status of Fucales species in the Mediterranean: are some species on the brink of extinction? Is their extinction at the scale of the French Riviera the harbinger of their extinction Mediterranean–wide?

  3. Reactivated Memories Compete for Expression After Pavlovian Extinction

    Science.gov (United States)

    Laborda, Mario A.; Miller, Ralph R.

    2012-01-01

    We view the response decrement resulting from extinction treatment as an interference effect, in which the reactivated memory from acquisition competes with the reactivated memory from extinction for behavioral expression. For each of these memories, reactivation is proportional to both the strength of the stimulus-outcome association and the quality of the facilitatory cues for that association which are present at test. Here we review basic extinction and recovery-from-extinction phenomena, showing how these effects are explicable in this associative interference framework. Moreover, this orientation has and continues to dictate efficient manipulations for minimizing recovery from extinction. This in turn suggests procedures that might reduce relapse from exposure therapy for a number of psychological disorders. Some of these manipulations enhance the facilitatory cues from extinction that are present at test, others strengthen the extinction association (i.e., CS-no outcome), and yet others seem to work by a combination of these two processes. PMID:22326812

  4. Running from fear: Exercise modulation of fear extinction.

    Science.gov (United States)

    Tanner, Margaret K; Hake, Holly S; Bouchet, Courtney A; Greenwood, Benjamin N

    2018-03-31

    Extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear tends to resurface even after successful extinction. Identification of novel strategies to enhance fear extinction and reduce fear relapse is of paramount importance to mental health. Exercise can enhance cognitive function, but it is not yet well understood whether exercise can be an effective augmentation strategy for fear extinction. In the current review, we present the current state of knowledge on the effects of exercise on fear extinction. Effects of exercise duration, explanations for conflicting results, and potential mechanisms, focusing on a hypothesized role for dopamine, are all discussed. We also provide new data suggesting that the timing in which acute exercise occurs relative to fear extinction, is a crucial variable in determining whether exercise can enhance fear extinction. Clinical implications and ideas to guide future research endeavors in this area are provided. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. A global synthesis of plant extinction rates in urban areas.

    Science.gov (United States)

    Hahs, Amy K; McDonnell, Mark J; McCarthy, Michael A; Vesk, Peter A; Corlett, Richard T; Norton, Briony A; Clemants, Steven E; Duncan, Richard P; Thompson, Ken; Schwartz, Mark W; Williams, Nicholas S G

    2009-11-01

    Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

  6. Role of the hippocampus in contextual modulation of fear extinction

    Institute of Scientific and Technical Information of China (English)

    Lingzhi Kong; Xihong Wu; Liang Li

    2008-01-01

    Fear extinction is an important form of emotional learning, and affects neural plasticity. Cue fear extinction is a classical form of inhibitory learning that can be used as an exposure-based treatment for phobia, because the long-term extinction memory produced during cue fear extinction can limit the over-expression of fear. The expression of this inhibitory memory partly depends on the context in which the extinction learning occurs. Studies such as transient inhibition, electrophysiology and brain imaging have proved that the hippocampus - an important structure in the limbic system - facilitates memory retrieval by contextual cues.Mediation of the hippocampus-medial prefrontal lobe circuit may be the neurobiological basis of this process.This article has reviewed the role of the hippocampus in the learning and retrieval of fear extinction.Contextual modulation of fear extinction may rely on a neural network consisting of the hippocampus, the medial prefrontal cortex and the amygdala.

  7. Epidemic extinction paths in complex networks

    Science.gov (United States)

    Hindes, Jason; Schwartz, Ira B.

    2017-05-01

    We study the extinction of long-lived epidemics on finite complex networks induced by intrinsic noise. Applying analytical techniques to the stochastic susceptible-infected-susceptible model, we predict the distribution of large fluctuations, the most probable or optimal path through a network that leads to a disease-free state from an endemic state, and the average extinction time in general configurations. Our predictions agree with Monte Carlo simulations on several networks, including synthetic weighted and degree-distributed networks with degree correlations, and an empirical high school contact network. In addition, our approach quantifies characteristic scaling patterns for the optimal path and distribution of large fluctuations, both near and away from the epidemic threshold, in networks with heterogeneous eigenvector centrality and degree distributions.

  8. Extinction of corrugated hydrogen/air flames

    International Nuclear Information System (INIS)

    Mizomoto, M.; Asaka, Y.; Ikai, S.; Law, C.K.

    1982-01-01

    Recent studies on flammability limits reveal the importance of flow nonuniformity, flame curvature, and molecular and thermal diffusivities in determining the extinguishability and the associated limits of premixed fuel/air flames. In particular, it is found that conditions which favor extinction of a lean flame may cause intensification of a rich flame. In the present study the authors have experimentally determined the extinction characteristics and limits of highly curved hydrogen/air flames as represented by the opening of bunsen flame tips. Results show that the tip opens at a constant fuel equivalence ratio of phi = 1.15, regardless of the velocity and uniformity of the upstream flow. This critical mixture concentration, while being rich, is still on the lean side of that corresponding to the maximum burning velocity (phi = 1.8), implying that for highly diffusive systems, the relevant reference concentration is that for maximum burning velocity instead of stoichiometry

  9. The galactic extinction towards Maffei 1

    International Nuclear Information System (INIS)

    Buta, R.J.; McCall, M.L.; McDonald Observatory, Austin, TX; Australian National Univ., Canberra. Mount Stromlo and Siding Spring Observatories)

    1983-01-01

    The extinction of Maffei 1 has been measured by two new techniques. First, BV aperture photometry has been performed to obtain the colour excess from standard aperture-colour relations for early-type galaxies. Secondly, millimetre and radio observations of galactic CO and HI have been used to calculate the total hydrogen column density along the line-of-sight, and thereby estimate the colour excess from the local dust-to-gas ratio. After consideration of all extinction measurements to date, it is concluded that Asub(v)=5.1+-0.2 mag. The isophotal diameter and the corrected apparent visual magnitude are estimated to be approx. 15 arcmin and approx. 6.3 respectively (assuming type E), making Maffei 1 one of the biggest and brightest galaxies in the sky. (author)

  10. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2011-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  11. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  12. Geometrical scaling of jet fragmentation photons

    Energy Technology Data Exchange (ETDEWEB)

    Hattori, Koichi, E-mail: koichi.hattori@riken.jp [RIKEN BNL Research Center, Brookhaven National Laboratory, Upton NY 11973 (United States); Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); McLerran, Larry, E-mail: mclerran@bnl.gov [RIKEN BNL Research Center, Brookhaven National Laboratory, Upton NY 11973 (United States); Physics Dept., Bdg. 510A, Brookhaven National Laboratory, Upton, NY-11973 (United States); Physics Dept., China Central Normal University, Wuhan (China); Schenke, Björn, E-mail: bschenke@bnl.gov [Physics Dept., Bdg. 510A, Brookhaven National Laboratory, Upton, NY-11973 (United States)

    2016-12-15

    We discuss jet fragmentation photons in ultrarelativistic heavy-ion collisions. We argue that, if the jet distribution satisfies geometrical scaling and an anisotropic spectrum, these properties are transferred to photons during the jet fragmentation.

  13. Transition in synthetic jets

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav; Kordík, Jozef

    2012-01-01

    Roč. 187, NOV 2012 (2012), s. 105-117 ISSN 0924-4247 R&D Projects: GA TA ČR(CZ) TA02020795; GA ČR(CZ) GPP101/12/P556; GA ČR(CZ) GCP101/11/J019 Institutional research plan: CEZ:AV0Z20760514 Keywords : turbulence * synthetic jet * transition * velocity spectra Subject RIV: BK - Fluid Dynamics Impact factor: 1.841, year: 2012 http://www. science direct.com/ science /article/pii/S0924424712005031

  14. Hadron jets in perspective

    International Nuclear Information System (INIS)

    Quigg, C.

    1982-11-01

    The subject of hadron jet studies, to judge by the work presented at this workshop, is a maturing field which is still gathering steam. The very detailed work being done in lepton-lepton and lepton-hadron collisions, the second-generation measurements being carried out at Fermilab, the CERN SPS, and the ISR, and the very high energy hard scatterings being observed at the CERN Collider all show enormous promise for increased understanding. Perhaps we shall yet reach that long-sought nirvana in which high-p/sub perpendicular/ collisions become truly simple

  15. Jet physics at LEP

    International Nuclear Information System (INIS)

    Venus, W.

    1991-01-01

    The results of studies of the jet structure of hadronic Z 0 decays performed in the first year of Large Electron-Positron collider (LEP) operation are reviewed. The measurements of the quantum chromodynamics (QCD) coupling constant α s (M z )and the detection of the presence of the triple gluon vertex are summarized. After a brief review of the promising status of QCD in relation to even the very soft processes, the running of the coupling constants to high energy is considered in the context of grand unified theories. The necessity and importance of further theoretical work is stressed. (author)

  16. Extinction risk under coloured environmental noise

    OpenAIRE

    Heino, M; Ripa, Jörgen; Kaitala, V

    2000-01-01

    Positively autocorrelated red environmental noise is characterized by a strong dependence of expected sample variance on sample length. This dependence has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, but only at a chosen time scale. We show with a simple one-dimensional population dynamics model that the different but equ...

  17. Immunological systematics of the extinct quagga (Equidae).

    Science.gov (United States)

    Lowenstein, J M; Ryder, O A

    1985-09-15

    It has been debated whether the extinct quagga was a distinct fourth species of African zebra or whether it was merely the southern variant of the Plains zebra (Equus burchelli). Using a radioimmunoassay (RIA) technique, we have shown that proteins remaining in quagga skins from museums are much more similar to serum proteins of the Plains zebra than to those of the other two extant zebras.

  18. Rewinding the process of mammalian extinction

    OpenAIRE

    Saragusty, J.; Diecke, S.; Drukker, M.; Durrant, B.; Friedrich Ben-Nun, I.; Galli, C.; Goeritz, F.; Hayashi, K.; Hermes, R.; Holtze, S.; Johnson, S.; Lazzari, G.; Loi, P.; Loring, J.F.; Okita, K.

    2016-01-01

    With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road m...

  19. Opportunities and costs for preventing vertebrate extinctions.

    Science.gov (United States)

    Conde, Dalia A; Colchero, Fernando; Güneralp, Burak; Gusset, Markus; Skolnik, Ben; Parr, Michael; Byers, Onnie; Johnson, Kevin; Young, Glyn; Flesness, Nate; Possingham, Hugh; Fa, John E

    2015-03-16

    Despite an increase in policy and management responses to the global biodiversity crisis, implementation of the 20 Aichi Biodiversity Targets still shows insufficient progress [1]. These targets, strategic goals defined by the United Nations Convention on Biological Diversity (CBD), address major causes of biodiversity loss in part by establishing protected areas (Target 11) and preventing species extinctions (Target 12). To achieve this, increased interventions will be required for a large number of sites and species. The Alliance for Zero Extinction (AZE) [2], a consortium of conservation-oriented organisations that aims to protect Critically Endangered and Endangered species restricted to single sites, has identified 920 species of mammals, birds, amphibians, reptiles, conifers and reef-building corals in 588 'trigger' sites [3]. These are arguably the most irreplaceable category of important biodiversity conservation sites. Protected area coverage of AZE sites is a key indicator of progress towards Target 11 [1]. Moreover, effective conservation of AZE sites is essential to achieve Target 12, as the loss of any of these sites would certainly result in the global extinction of at least one species [2]. However, averting human-induced species extinctions within AZE sites requires enhanced planning tools to increase the chances of success [3]. Here, we assess the potential for ensuring the long-term conservation of AZE vertebrate species (157 mammals, 165 birds, 17 reptiles and 502 amphibians) by calculating a conservation opportunity index (COI) for each species. The COI encompasses a set of measurable indicators that quantify the possibility of achieving successful conservation of a species in its natural habitat (COIh) and by establishing insurance populations in zoos (COIc). Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Parrots and macaws: Species in extinction danger?

    International Nuclear Information System (INIS)

    Castro ramirez, Jose; Moyano P, Edgar A

    1994-01-01

    The paper refers to the privileged position of Colombia due to their position in the tropic, the influence of two oceans, their wide hydrographic net, variety of climates, etc; they make that Colombia occupies first places in biodiversity; but due to the indiscriminate pruning of primary forest, they make that this enormous biological potential is seriously threatened, where many of its birds are in extinction road

  1. Numerical and experimental study of pulse-jet cleaning in fabric filters

    DEFF Research Database (Denmark)

    O. Andersen, B.; Nielsen, N. F.; Walther, J. H.

    2016-01-01

    Pulse-jet cleaning and understanding of the complex physics are essential when designing fabric filters used for air pollution control. Today, low-pressure cleaning is of particular interest due to demand for reduced compressed air consumption. Pulse-jet cleaned fabric filters have been studied......-pressure fabric filters (2 bar) is studied using a full three-dimensional (3D) CFD model. Experimental results obtained in a pilot-scale test filter with 28 bags, in length of 10 m and in general full-scale dimensions of the cleaning system are used to verify the reliability of the present CFD model....... The validated CFD model reveals the strong compressible effects, a highly transient behaviour, the formation of compressible vortex rings and the shock cell phenomenon within the overexpanded supersonic jet. The cleaning nozzles and venturi design aid or oppose the pulse-pressure within the bags, and this plays...

  2. Pathways to extinction: beyond the error threshold.

    Science.gov (United States)

    Manrubia, Susanna C; Domingo, Esteban; Lázaro, Ester

    2010-06-27

    Since the introduction of the quasispecies and the error catastrophe concepts for molecular evolution by Eigen and their subsequent application to viral populations, increased mutagenesis has become a common strategy to cause the extinction of viral infectivity. Nevertheless, the high complexity of virus populations has shown that viral extinction can occur through several other pathways apart from crossing an error threshold. Increases in the mutation rate enhance the appearance of defective forms and promote the selection of mechanisms that are able to counteract the accelerated appearance of mutations. Current models of viral evolution take into account more realistic scenarios that consider compensatory and lethal mutations, a highly redundant genotype-to-phenotype map, rough fitness landscapes relating phenotype and fitness, and where phenotype is described as a set of interdependent traits. Further, viral populations cannot be understood without specifying the characteristics of the environment where they evolve and adapt. Altogether, it turns out that the pathways through which viral quasispecies go extinct are multiple and diverse.

  3. Interstellar Extinction in 20 Open Star Clusters

    Science.gov (United States)

    Rangwal, Geeta; Yadav, R. K. S.; Durgapal, Alok K.; Bisht, D.

    2017-12-01

    The interstellar extinction law in 20 open star clusters namely, Berkeley 7, Collinder 69, Hogg 10, NGC 2362, Czernik 43, NGC 6530, NGC 6871, Bochum 10, Haffner 18, IC 4996, NGC 2384, NGC 6193, NGC 6618, NGC 7160, Collinder 232, Haffner 19, NGC 2401, NGC 6231, NGC 6823, and NGC 7380 have been studied in the optical and near-IR wavelength ranges. The difference between maximum and minimum values of E(B - V) indicates the presence of non-uniform extinction in all the clusters except Collinder 69, NGC 2362, and NGC 2384. The colour excess ratios are consistent with a normal extinction law for the clusters NGC 6823, Haffner 18, Haffner 19, NGC 7160, NGC 6193, NGC 2401, NGC 2384, NGC 6871, NGC 7380, Berkeley 7, Collinder 69, and IC 4996. We have found that the differential colour-excess ΔE(B - V), which may be due to the occurrence of dust and gas inside the clusters, decreases with the age of the clusters. A spatial variation of colour excess is found in NGC 6193 in the sense that it decreases from east to west in the cluster region. For the clusters Berkeley 7, NGC 7380, and NGC 6871, a dependence of colour excess E(B - V) with spectral class and luminosity is observed. Eight stars in Collinder 232, four stars in NGC 6530, and one star in NGC 6231 have excess flux in near-IR. This indicates that these stars may have circumstellar material around them.

  4. Mathematical Modeling of Extinction of Inhomogeneous Populations

    Science.gov (United States)

    Karev, G.P.; Kareva, I.

    2016-01-01

    Mathematical models of population extinction have a variety of applications in such areas as ecology, paleontology and conservation biology. Here we propose and investigate two types of sub-exponential models of population extinction. Unlike the more traditional exponential models, the life duration of sub-exponential models is finite. In the first model, the population is assumed to be composed clones that are independent from each other. In the second model, we assume that the size of the population as a whole decreases according to the sub-exponential equation. We then investigate the “unobserved heterogeneity”, i.e. the underlying inhomogeneous population model, and calculate the distribution of frequencies of clones for both models. We show that the dynamics of frequencies in the first model is governed by the principle of minimum of Tsallis information loss. In the second model, the notion of “internal population time” is proposed; with respect to the internal time, the dynamics of frequencies is governed by the principle of minimum of Shannon information loss. The results of this analysis show that the principle of minimum of information loss is the underlying law for the evolution of a broad class of models of population extinction. Finally, we propose a possible application of this modeling framework to mechanisms underlying time perception. PMID:27090117

  5. Area-based assessment of extinction risk.

    Science.gov (United States)

    Hei, Fangliang

    2012-05-01

    Underpinning the International Union for Conservation of Nature (IUCN) Red List is the assessment of extinction risk as determined by the size and degree of loss of populations. The IUCN system lists a species as Critically Endangered, Endangered, or Vulnerable if its population size declines 80%, 50%, or 30% within a given time frame. However, effective implementation of the system faces substantial challenges and uncertainty because geographic scale data on population size and long-term dynamics are scarce. I develop a model to quantify extinction risk using a measure based on a species' distribution, a much more readily obtained quantity. The model calculates the loss of the area of occupancy that is equivalent to the loss of a given proportion of a population. It is a very simple yet general model that has no free parameters and is independent of scale. The model predicted well the distributions of 302 tree species at a local scale and the distributions of 348 species of North American land birds. This area-based model provides a solution to the long-standing problem for IUCN assessments of lack of data on population sizes, and thus it will contribute to facilitating the quantification of extinction risk worldwide.

  6. Permo-Triassic vertebrate extinctions: A program

    Science.gov (United States)

    Olson, E. C.

    1988-01-01

    Since the time of the Authors' study on this subject, a great deal of new information has become available. Concepts of the nature of extinctions have changed materially. The Authors' conclusion that a catastrophic event was not responsible for the extinction of vertebrates has modified to the extent that hypotheses involving either the impact of a massive extra-terrestrial body or volcanism provide plausible but not currently fully testable hypotheses. Stated changes resulted in a rapid decrease in organic diversity, as the ratio of origins of taxa to extinctions shifted from strongly positive to negative, with momentary equilibrium being reached at about the Permo-Triassic boundary. The proximate causes of the changes in the terrestrial biota appear to lie in two primary factors: (1) strong climatic changes (global mean temperatures, temperature ranges, humidity) and (2) susceptibility of the dominant vertebrates (large dicynodonts) and the glossopteris flora to disruption of the equlibrium of the world ecosystem. The following proximate causes have been proposed: (1) rhythmic fluctuations in solar radiation, (2) tectonic events as Pangea assembled, altering land-ocean relationships, patterns of wind and water circulation and continental physiography, (3) volcanism, and (4) changes subsequent to impacts of one or more massive extra terrestrial objects, bodies or comets. These hypotheses are discussed.

  7. Rewinding the process of mammalian extinction.

    Science.gov (United States)

    Saragusty, Joseph; Diecke, Sebastian; Drukker, Micha; Durrant, Barbara; Friedrich Ben-Nun, Inbar; Galli, Cesare; Göritz, Frank; Hayashi, Katsuhiko; Hermes, Robert; Holtze, Susanne; Johnson, Stacey; Lazzari, Giovanna; Loi, Pasqualino; Loring, Jeanne F; Okita, Keisuke; Renfree, Marilyn B; Seet, Steven; Voracek, Thomas; Stejskal, Jan; Ryder, Oliver A; Hildebrandt, Thomas B

    2016-07-01

    With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road map that, if successfully implemented, would ultimately lead to a self-sustaining population of an extremely endangered species are outlined here. The ideas discussed here, while centered on the northern white rhinoceros, are equally applicable, after proper adjustments, to other mammals on the brink of extinction. Through implementation of these ideas we hope to establish the foundation for reversal of some of the effects of what has been termed the sixth mass extinction event in the history of Earth, and the first anthropogenic one. Zoo Biol. 35:280-292, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.

  8. Causes and timing of future biosphere extinctions

    Directory of Open Access Journals (Sweden)

    S. Franck

    2006-01-01

    Full Text Available We present a minimal model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the combined ocean and atmosphere reservoir. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. During the entire existence of the biosphere procaryotes are always present. 2 Gyr ago eucaryotic life first appears. The emergence of complex multicellular life is connected with an explosive increase in biomass and a strong decrease in Cambrian global surface temperature at about 0.54 Gyr ago. In the long-term future the three types of biosphere will die out in reverse sequence of their appearance. We show that there is no evidence for an implosion-like extinction in contrast to the Cambrian explosion. In dependence of their temperature tolerance complex multicellular life and eucaryotes become extinct in about 0.8–1.2 Gyr and 1.3–1.5 Gyr, respectively. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr.

  9. Interstellar extinction and polarization in the infrared

    International Nuclear Information System (INIS)

    Martin, P.G.; Whittet, D.C.B.

    1990-01-01

    The wavelength dependences of interstellar continuum extinction and polarization in the range 0.35-5 microns are examined. The existence of a universal extinction curve with power law index of about 1.8 extending from the near-IR to at least 5 microns appears to be established for both diffuse and dense cloud dust. The polarization yields evidence for some degree of universality in the 1.6-5 micron regime which may be represented by a power law with index 1.5-2.0, encompassing that for extinction. The form of the polarization curve in the IR seems independent of the wavelength at which the degree of polarization peaks in the optical, implying that variations in that wavelength are caused by changes in the optical properties of the particle at blue-visible rather than IR wavelengths. It is argued that the more significant alterations of the grain size distribution from one environment to another occur for the smaller particles. 47 refs

  10. AN ANALYSIS OF THE SHAPES OF INTERSTELLAR EXTINCTION CURVES. VI. THE NEAR-IR EXTINCTION LAW

    International Nuclear Information System (INIS)

    Fitzpatrick, E. L.; Massa, D.

    2009-01-01

    We combine new observations from the Hubble Space Telescope's Advanced Camera of Survey with existing data to investigate the wavelength dependence of near-IR (NIR) extinction. Previous studies suggest a power law form for NIR extinction, with a 'universal' value of the exponent, although some recent observations indicate that significant sight line-to-sight line variability may exist. We show that a power-law model for the NIR extinction provides an excellent fit to most extinction curves, but that the value of the power, β, varies significantly from sight line to sight line. Therefore, it seems that a 'universal NIR extinction law' is not possible. Instead, we find that as β decreases, R(V) ≡ A(V)/E(B - V) tends to increase, suggesting that NIR extinction curves which have been considered 'peculiar' may, in fact, be typical for different R(V) values. We show that the power-law parameters can depend on the wavelength interval used to derive them, with the β increasing as longer wavelengths are included. This result implies that extrapolating power-law fits to determine R(V) is unreliable. To avoid this problem, we adopt a different functional form for NIR extinction. This new form mimics a power law whose exponent increases with wavelength, has only two free parameters, can fit all of our curves over a longer wavelength baseline and to higher precision, and produces R(V) values which are consistent with independent estimates and commonly used methods for estimating R(V). Furthermore, unlike the power-law model, it gives R(V)s that are independent of the wavelength interval used to derive them. It also suggests that the relation R(V) = -1.36 E(K-V)/(E(B-V)) - 0.79 can estimate R(V) to ±0.12. Finally, we use model extinction curves to show that our extinction curves are in accord with theoretical expectations, and demonstrate how large samples of observational quantities can provide useful constraints on the grain properties.

  11. Magnetic Field Topology in Jets

    Science.gov (United States)

    Gardiner, T. A.; Frank, A.

    2000-01-01

    We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.

  12. Turbulent jet in confined counterflow

    Indian Academy of Sciences (India)

    framework for presenting the results of the flowfield and jet penetration length. ... A turbulent jet is a basic free shear flow and has received research attention (see, .... MBE76 identify this to be a transitional zone and for. √ .... higher return flow and also higher velocity from counterflow due to a narrower gap thus leading.

  13. Associated jet production at HERA

    CERN Document Server

    Bartels, Julius; de Roeck, A; Graudenz, Dirk; Wüsthoff, M

    1996-01-01

    We compare the BFKL prediction for the associated production of forward jets at HERA with fixed-order matrix element calculations taking into account the kinematical cuts imposed by experimental conditions. Comparison with H1 data of the 1993 run favours the BFKL prediction. As a further signal of BFKL dynamics, we propose to look for the azimuthal dependence of the forward jets.

  14. Consolidating NASA's Arc Jets

    Science.gov (United States)

    Balboni, John A.; Gokcen, Tahir; Hui, Frank C. L.; Graube, Peter; Morrissey, Patricia; Lewis, Ronald

    2015-01-01

    The paper describes the consolidation of NASA's high powered arc-jet testing at a single location. The existing plasma arc-jet wind tunnels located at the Johnson Space Center were relocated to Ames Research Center while maintaining NASA's technical capability to ground-test thermal protection system materials under simulated atmospheric entry convective heating. The testing conditions at JSC were reproduced and successfully demonstrated at ARC through close collaboration between the two centers. New equipment was installed at Ames to provide test gases of pure nitrogen mixed with pure oxygen, and for future nitrogen-carbon dioxide mixtures. A new control system was custom designed, installed and tested. Tests demonstrated the capability of the 10 MW constricted-segmented arc heater at Ames meets the requirements of the major customer, NASA's Orion program. Solutions from an advanced computational fluid dynamics code were used to aid in characterizing the properties of the plasma stream and the surface environment on the calorimeters in the supersonic flow stream produced by the arc heater.

  15. LHCb; LHCb Jet Reconstruction

    CERN Multimedia

    Augusto, O

    2012-01-01

    The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than $4 \\times 10^{32} cm^{-2} s^{-1}$ and the integrated luminosity reached the value of 1.02 $fb^{-1}$ on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test pertubative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space $\\eta \\times \\phi$ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the calo...

  16. Disruption prediction at JET

    International Nuclear Information System (INIS)

    Milani, F.

    1998-12-01

    The sudden loss of the plasma magnetic confinement, known as disruption, is one of the major issue in a nuclear fusion machine as JET (Joint European Torus). Disruptions pose very serious problems to the safety of the machine. The energy stored in the plasma is released to the machine structure in few milliseconds resulting in forces that at JET reach several Mega Newtons. The problem is even more severe in the nuclear fusion power station where the forces are in the order of one hundred Mega Newtons. The events that occur during a disruption are still not well understood even if some mechanisms that can lead to a disruption have been identified and can be used to predict them. Unfortunately it is always a combination of these events that generates a disruption and therefore it is not possible to use simple algorithms to predict it. This thesis analyses the possibility of using neural network algorithms to predict plasma disruptions in real time. This involves the determination of plasma parameters every few milliseconds. A plasma boundary reconstruction algorithm, XLOC, has been developed in collaboration with Dr. D. O'Brien and Dr. J. Ellis capable of determining the plasma wall/distance every 2 milliseconds. The XLOC output has been used to develop a multilayer perceptron network to determine plasma parameters as l i and q ψ with which a machine operational space has been experimentally defined. If the limits of this operational space are breached the disruption probability increases considerably. Another approach for prediction disruptions is to use neural network classification methods to define the JET operational space. Two methods have been studied. The first method uses a multilayer perceptron network with softmax activation function for the output layer. This method can be used for classifying the input patterns in various classes. In this case the plasma input patterns have been divided between disrupting and safe patterns, giving the possibility of

  17. Nucleosynthesis in Jets from Collapsars

    International Nuclear Information System (INIS)

    Fujimoto, Shin-ichiro; Nishimura, Nobuya; Hashimoto, Masa-aki

    2008-01-01

    We investigate nucleosynthesis inside magnetically driven jets ejected from collapsars, or rotating magnetized stars collapsing to a black hole, based on two-dimensional magnetohydrodynamic simulation of the collapsars during the core collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase using a large nuclear reaction network. We find that the r-process successfully operates only in the energetic jets (>10 51 erg), so that U and Th are synthesized abundantly, even when the collapsars have a relatively small magnetic field (10 10 G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to that of the r-elements in the solar system. The higher energy jets have larger amounts of 56 Ni. Less energetic jets, which have small amounts of 56 Ni, could induce GRB without supernova, such as GRB060505 and GRB060614

  18. Magnetically driven jets and winds

    Science.gov (United States)

    Lovelace, R. V. E.; Berk, H. L.; Contopoulos, J.

    1991-01-01

    Four equations for the origin and propagation of nonrelativistic jets and winds are derived from the basic conservation laws of ideal MHD. The axial current density is negative in the vicinity of the axis and positive at larger radii; there is no net current because this is energetically favored. The magnetic field is essential for the jet solutions in that the zz-component of the magnetic stress acts, in opposition to gravity, to drive matter through the slow magnetosonic critical point. For a representative self-consistent disk/jet solution relevant to a protostellar system, the reaction of the accreted mass expelled in the jets is 0.1, the ratio of the power carried by the jets to the disk luminosity is 0.66, and the ratio of the boundary layer to disk luminosities is less than about 0.13. The star's rotation rate decreases with time even for rotation rates much less than the breakup rate.

  19. One extinct turtle species less: Pelusios seychellensis is not extinct, it never existed.

    Directory of Open Access Journals (Sweden)

    Heiko Stuckas

    Full Text Available Pelusios seychellensis is thought to be a freshwater turtle species endemic to the island of Mahé, Seychelles. There are only three museum specimens from the late 19(th century known. The species has been never found again, despite intensive searches on Mahé. Therefore, P. seychellensis has been declared as "Extinct" by the IUCN and is the sole putatively extinct freshwater turtle species. Using DNA sequences of three mitochondrial genes of the historical type specimen and phylogenetic analyses including all other species of the genus, we provide evidence that the description of P. seychellensis was erroneously based on a widely distributed West African species, P. castaneus. Consequently, we synonymize the two species and delete P. seychellensis from the list of extinct chelonian species and from the faunal list of the Seychelles.

  20. A window of vulnerability: impaired fear extinction in adolescence.

    Science.gov (United States)

    Baker, Kathryn D; Den, Miriam L; Graham, Bronwyn M; Richardson, Rick

    2014-09-01

    There have been significant advances made towards understanding the processes mediating extinction of learned fear. However, despite being of clear theoretical and clinical significance, very few studies have examined fear extinction in adolescence, which is often described as a developmental window of vulnerability to psychological disorders. This paper reviews the relatively small body of research examining fear extinction in adolescence. A prominent finding of this work is that adolescents, both humans and rodents, exhibit a marked impairment in extinction relative to both younger (e.g., juvenile) and older (e.g., adult) groups. We then review some potential mechanisms that could produce the striking extinction deficit observed in adolescence. For example, one neurobiological candidate mechanism for impaired extinction in adolescence involves changes in the functional connectivity within the fear extinction circuit, particularly between prefrontal cortical regions and the amygdala. In addition, we review research on emotion regulation and attention processes that suggests that developmental changes in attention bias to threatening cues may be a cognitive mechanism that mediates age-related differences in extinction learning. We also examine how a differential reaction to chronic stress in adolescence impacts upon extinction retention during adolescence as well as in later life. Finally, we consider the findings of several studies illustrating promising approaches that overcome the typically-observed extinction impairments in adolescent rodents and that could be translated to human adolescents. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Cortisol modifies extinction learning of recently acquired fear in men

    Science.gov (United States)

    Hermann, Andrea; Stark, Rudolf; Wolf, Oliver Tobias

    2014-01-01

    Exposure therapy builds on the mechanism of fear extinction leading to decreased fear responses. How the stress hormone cortisol affects brain regions involved in fear extinction in humans is unknown. For this reason, we tested 32 men randomly assigned to receive either 30 mg hydrocortisone or placebo 45 min before fear extinction. In fear acquisition, a picture of a geometrical figure was either partially paired (conditioned stimulus; CS+) or not paired (CS−) with an electrical stimulation (unconditioned stimulus; UCS). In fear extinction, each CS was presented again, but no UCS occurred. Cortisol increased conditioned skin conductance responses in early and late extinction. In early extinction, higher activation towards the CS− than to the CS+ was found in the amygdala, hippocampus and posterior parahippocampal gyrus. This pattern might be associated with the establishment of a new memory trace. In late extinction, the placebo compared with the cortisol group displayed enhanced CS+/CS− differentiation in the amygdala, medial frontal cortex and nucleus accumbens. A change from early deactivation to late activation of the extinction circuit as seen in the placebo group seems to be needed to enhance extinction and to reduce fear. Cortisol appears to interfere with this process thereby impairing extinction of recently acquired conditioned fear. PMID:23945999

  2. Candesartan ameliorates impaired fear extinction induced by innate immune activation.

    Science.gov (United States)

    Quiñones, María M; Maldonado, Lizette; Velazquez, Bethzaly; Porter, James T

    2016-02-01

    Patients with post-traumatic stress disorder (PTSD) tend to show signs of a relatively increased inflammatory state suggesting that activation of the immune system may contribute to the development of PTSD. In the present study, we tested whether activation of the innate immune system can disrupt acquisition or recall of auditory fear extinction using an animal model of PTSD. Male adolescent rats received auditory fear conditioning in context A. The next day, an intraperitoneal injection of lipopolysaccharide (LPS; 100 μg/kg) prior to auditory fear extinction in context B impaired acquisition and recall of extinction. LPS (100 μg/kg) given after extinction training did not impair extinction recall suggesting that LPS did not affect consolidation of extinction. In contrast to cued fear extinction, contextual fear extinction was not affected by prior injection of LPS (100 μg/kg). Although LPS also reduced locomotion, we could dissociate the effects of LPS on extinction and locomotion by using a lower dose of LPS (50 μg/kg) which impaired locomotion without affecting extinction. In addition, 15 h after an injection of 250 μg/kg LPS in adult rats, extinction learning and recall were impaired without affecting locomotion. A sub-chronic treatment with candesartan, an angiotensin II type 1 receptor blocker, prevented the LPS-induced impairment of extinction in adult rats. Our results demonstrate that activation of the innate immune system can disrupt auditory fear extinction in adolescent and adult animals. These findings also provide direction for clinical studies of novel treatments that modulate the innate immune system for stress-related disorders like PTSD. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Characteristics of premixed flames stabilized in an axisymmetric curved-wall jet burner with tip modification

    KAUST Repository

    Kim, Daejoong

    2009-11-10

    The stabilization characteristics of premixed flames in an axisymmetric curved-wall jet burner have been experimentally investigated. This burner utilized the Coanda effect on top of a burner tip. The initially spherical burner tip was modified to a flat tip and a concave tip in order to improve flame stabilization by providing enough space for flow recirculation above the burner tip region. The flow characteristics have been visualized using a schlieren technique. Small-scale turbulence structure has been observed mainly in the interaction jet region (located downstream of the recirculation region) for large jet velocity (Reynolds number >11,500). An appreciable amount of air entrainment was exhibited from the half-angle of the jet spread, approximately 20. The averaged planar laser-induced fluorescence images of the flames for this large velocity demonstrated that the strong signal of OH radicals, representing reaction zones, existed in the recirculation zone, while it was weak in the interaction jet region due to intermittency and local extinction by the generation of small scale turbulence. The OH radical signals strengthened again in the merged jet region (downstream of the interaction jet region). In extreme cases of Reynolds number over 19,000, a unique flame exhibiting OH radicals only in the recirculation zone was observed for the concave tip. The flame stabilization has been mapped by varying jet velocity and equivalence ratio, and the result showed that the stabilization characteristics were improved appreciably from the initial spherical tip design, especially for rich mixtures. The flow fields measured by a laser Doppler velocimetry confirmed the existence of recirculation zone and the expansion of the recirculation zones for the modified tips. The temperature profile measured by a coherent anti-Stokes Raman spectroscopy exhibited an intermittent nature, especially near the recirculation zone.

  4. Mutually opposing forces during locomotion can eliminate the tradeoff between maneuverability and stability

    Science.gov (United States)

    Cowan, Noah; Sefati, Shahin; Neveln, Izaak; Roth, Eatai; Mitchell, Terence; Snyder, James; Maciver, Malcolm; Fortune, Eric

    A surprising feature of animal locomotion is that organisms typically produce substantial forces in directions other than what is necessary to move the animal through its environment, such as perpendicular to, or counter to, the direction of travel. The effect of these forces has been difficult to observe because they are often mutually opposing and therefore cancel out. Using a combination of robotic physical modeling, computational modeling, and biological experiments, we discovered that these forces serve an important role: to simplify and enhance the control of locomotion. Specifically, we examined a well-suited model system, the glass knifefish Eigenmannia virescens, which produces mutually opposing forces during a hovering behavior. By systematically varying the locomotor parameters of our biomimetic robot, and measuring the resulting forces and kinematics, we demonstrated that the production and differential control of mutually opposing forces is a strategy that generates passive stabilization while simultaneously enhancing maneuverability. Mutually opposing forces during locomotion are widespread across animal taxa, and these results indicate that such forces can eliminate the tradeoff between stability and maneuverability, thereby simplifying robotic and neural control.

  5. POLYCYCLIC AROMATIC HYDROCARBON FORMATION IN OPPOSED FLOW DIFFUSION FLAMES OF ETHANE. (R825412)

    Science.gov (United States)

    AbstractThe effect of fuel-side carbon density on the levels of polycyclic aromatic hydrocarbon (PAH) formation in atmospheric pressure, opposed flow, ethane diffusion flames has been studied using heated micro-probe sampling and gas chromatography/mass spectrometry (...

  6. MRI of bone marrow: opposed-phase gradient-echo sequences with long repetition time

    International Nuclear Information System (INIS)

    Seiderer, M.; Staebler, A.; Wagner, H.

    1999-01-01

    Signal intensity for opposed-phase gradient-echo (GE) sequences of tissues composed of fat- and water-equivalent cells such as red bone marrow is extremely sensitive to variation of the ratio of both cell populations (fat-to-water ratio Q F/W ). Because most bone marrow pathology results in variation of Q F/W , GE sequences are characterized by high-contrast imaging of pathology. The aim of this study was to evaluate the influence of TR, TE, FA, Q F/W and histology on signal intensity. Signal intensity of opposed-phase GE sequences as a function of TR, TE, FA, and Q F/W was measured for a fat-water phantom and cadaver specimens of normal bone marrow (red and yellow) and pathological bone marrow (tumors). All specimens were correlated to histology. Opposed-phase GE imaging of red bone marrow pathology results in low-signal-intensity imaging of intact red bone marrow and high-signal-intensity positive contrast imaging of pathology associated with a change in Q F/W . In first-order approximation the signal intensity of pathology is linearly correlated to the change in Q F/W . Opposed-phase GE imaging is a sensitive imaging technique for red bone marrow pathology. Relative contrast of red bone marrow pathology is similar to fat-suppressed imaging techniques. Acquisition time is identical to T1-weighted SE sequences. (orig.)

  7. Attitudes toward hydraulic fracturing: The opposing forces of political conservatism and basic knowledge about fracking

    OpenAIRE

    Choma, BL; Hanoch, Y; Currie, S

    2016-01-01

    publisher: Elsevier articletitle: Attitudes toward hydraulic fracturing: The opposing forces of political conservatism and basic knowledge about fracking journaltitle: Global Environmental Change articlelink: http://dx.doi.org/10.1016/j.gloenvcha.2016.03.004 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved.

  8. Mass extinction efficiency and extinction hygroscopicity of ambient PM2.5 in urban China.

    Science.gov (United States)

    Cheng, Zhen; Ma, Xin; He, Yujie; Jiang, Jingkun; Wang, Xiaoliang; Wang, Yungang; Sheng, Li; Hu, Jiangkai; Yan, Naiqiang

    2017-07-01

    The ambient PM 2.5 pollution problem in China has drawn substantial international attentions. The mass extinction efficiency (MEE) and hygroscopicity factor (f(RH)) of PM 2.5 can be readily applied to study the impacts on atmospheric visibility and climate. The few previous investigations in China only reported results from pilot studies and are lack of spatial representativeness. In this study, hourly average ambient PM 2.5 mass concentration, relative humidity, and atmospheric visibility data from China national air quality and meteorological monitoring networks were retrieved and analyzed. It includes 24 major Chinese cities from nine city-clusters with the period of October 2013 to September 2014. Annual average extinction coefficient in urban China was 759.3±258.3Mm -1 , mainly caused by dry PM 2.5 (305.8.2±131.0Mm -1 ) and its hygroscopicity (414.6±188.1Mm -1 ). High extinction coefficient values were resulted from both high ambient PM 2.5 concentration (68.5±21.7µg/m 3 ) and high relative humidity (69.7±8.6%). The PM 2.5 mass extinction efficiency varied from 2.87 to 6.64m 2 /g with an average of 4.40±0.84m 2 /g. The average extinction hygroscopic factor f(RH=80%) was 2.63±0.45. The levels of PM 2.5 mass extinction efficiency and hygroscopic factor in China were in comparable range with those found in developed countries in spite of the significant diversities among all 24 cities. Our findings help to establish quantitative relationship between ambient extinction coefficient (visual range) and PM 2.5 & relative humidity. It will reduce the uncertainty of extinction coefficient estimation of ambient PM 2.5 in urban China which is essential for the research of haze pollution and climate radiative forcing. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Inclusive jet cross sections and jet shapes at CDF

    International Nuclear Information System (INIS)

    Wainer, N.

    1991-09-01

    The inclusive jet cross section and jet shapes at √s = 1.8 TeV have been measured by CDF at the Fermilab Tevatron Collider. results are compared to recent next-to-leading order QCD calculations, which predict variation of the cross section with cone size, as well as variation of the jet shape with energy. A lower limit on the parameter Λ c , which characterize a contact interaction associated with quark sub-structure is determined to be 1400 GeV at the 95% confidence level. 3 refs., 4 figs

  10. First experiments in JET

    International Nuclear Information System (INIS)

    Rebut, P.H.; Bartlett, D.V.; Baeumel, G.

    1985-01-01

    Results obtained from JET since June 1983 are described which show that this large tokamak behaves in a similar manner to smaller tokamaks, but with correspondingly improved plasma parameters. Long-duration hydrogen and deuterium plasmas (>10 s) have been obtained with electron temperatures reaching >4 keV for power dissipations =1.6), loss of vertical stability occurred, as expected from previous calculations. Forces of several hundred tonnes (at Isub(p)=2.7 MA) were transmitted to the vacuum vessel. Measured confinement times are larger than the corresponding INTOR values. The maximum achievable density is limited by disruptions. Impurity levels determine this limiting density, and the paper concludes with proposals to reduce these. In addition, progress in neutral injection and RF heating is described, as well as preparations for D-T operation. (author)

  11. JET flywheel generators

    International Nuclear Information System (INIS)

    Huart, M.; Sonnerup, L.

    1986-01-01

    Two large vertical shaft flywheel generators each provides the JET device with peak power up to 400 MW and energy up to 2600 MJ per pulse to induce and confine the multi-mega-ampere plasma current. The integrated rotor flywheel consists of a 650 tonne/10 m diameter rim carrying the poles of the machine. The energy is stored kinetically during a 9 min interval of acceleration from half-speed to full-speed and then released during a 20 s long deceleration. A design life of 100 000 cycles at full energy rating was specified. The mechanical design and construction of the generators is reviewed. Particular attention is paid to the assessment of the stresses and fatigue life of the rotor system, its dynamic behaviour (rim movement, critical speed and balancing) and on the performance in operation of the large thrust bearing. (author)

  12. JET pump limiter

    International Nuclear Information System (INIS)

    Sonnenberg, K.; Deksnis, E.; Shaw, R.; Reiter, D.

    1988-01-01

    JET plans to install two pump limiter modules which can be used for belt-limiter, inner-wall and X-point discharges and, also, for 1-2s as the main limiter. A design is presented which is compatible with two diagnostic systems, and which allows partial removal of the pump limiter to provide access for remote-handling operations. The high heat-flux components are initially cooled during a pulse. Heat is removed between discharges by radiation and pressure contacts to a water-cooled support structure. The pumping edge will be made of annealed pyrolytic graphite. Exhaust efficiency has been estimated, for a 1-d edge model, using a Monte-Carlo calculation of neutral gas transport. When the pump limiter is operated together with other wall components we expect an efficiency of ≅ 5% (2.5 x 10 21 part/s). As a main limiter the efficiency increases to about 10%. (author)

  13. Ecological selectivity of the emerging mass extinction in the oceans.

    Science.gov (United States)

    Payne, Jonathan L; Bush, Andrew M; Heim, Noel A; Knope, Matthew L; McCauley, Douglas J

    2016-09-16

    To better predict the ecological and evolutionary effects of the emerging biodiversity crisis in the modern oceans, we compared the association between extinction threat and ecological traits in modern marine animals to associations observed during past extinction events using a database of 2497 marine vertebrate and mollusc genera. We find that extinction threat in the modern oceans is strongly associated with large body size, whereas past extinction events were either nonselective or preferentially removed smaller-bodied taxa. Pelagic animals were victimized more than benthic animals during previous mass extinctions but are not preferentially threatened in the modern ocean. The differential importance of large-bodied animals to ecosystem function portends greater future ecological disruption than that caused by similar levels of taxonomic loss in past mass extinction events. Copyright © 2016, American Association for the Advancement of Science.

  14. Aging accelerates memory extinction and impairs memory restoration in Drosophila.

    Science.gov (United States)

    Chen, Nannan; Guo, Aike; Li, Yan

    2015-05-15

    Age-related memory impairment (AMI) is a phenomenon observed from invertebrates to human. Memory extinction is proposed to be an active inhibitory modification of memory, however, whether extinction is affected in aging animals remains to be elucidated. Employing a modified paradigm for studying memory extinction in fruit flies, we found that only the stable, but not the labile memory component was suppressed by extinction, thus effectively resulting in higher memory loss in aging flies. Strikingly, young flies were able to fully restore the stable memory component 3 h post extinction, while aging flies failed to do so. In conclusion, our findings reveal that both accelerated extinction and impaired restoration contribute to memory impairment in aging animals. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Reintroducing resurrected species: selecting DeExtinction candidates.

    Science.gov (United States)

    Seddon, Philip J; Moehrenschlager, Axel; Ewen, John

    2014-03-01

    Technological advances have raised the controversial prospect of resurrecting extinct species. Species DeExtinction should involve more than the production of biological orphans to be scrutinized in the laboratory or zoo. If DeExtinction is to realize its stated goals of deep ecological enrichment, then resurrected animals must be translocated (i.e., released within suitable habitat). Therefore, DeExtinction is a conservation translocation issue and the selection of potential DeExtinction candidates must consider the feasibility and risks associated with reintroduction. The International Union for the Conservation of Nature (IUCN) Guidelines on Reintroductions and Other Conservation Translocations provide a framework for DeExtinction candidate selection. We translate these Guidelines into ten questions to be addressed early on in the selection process to eliminate unsuitable reintroduction candidates. We apply these questions to the thylacine, Yangtze River Dolphin, and Xerces blue butterfly. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Clues from Bent Jets

    Science.gov (United States)

    Kohler, Susanna

    2018-04-01

    Powerful jets emitted from the centers of distant galaxies make for spectacular signposts in the radio sky. Can observations of these jets reveal information about the environments that surround them?Signposts in the SkyVLA FIRST images of seven bent double-lobed radio galaxies from the authors sample. [Adapted from Silverstein et al. 2018]An active supermassive black hole lurking in a galactic center can put on quite a show! These beasts fling out accreting material, often forming intense jets that punch their way out of their host galaxies. As the jets propagate, they expand into large lobes of radio emission that we can spot from Earth observable signs of the connection between distant supermassive black holes and the galaxies in which they live.These distinctive double-lobed radio galaxies (DLRGs) dont all look the same. In particular, though the jets are emitted from the black holes two poles, the lobes of DLRGs dont always extend perfectly in opposite directions; often, the jets become bent on larger scales, appearing to us to subtend angles of less than 180 degrees.Can we use our observations of DLRG shapes and distributions to learn about their surroundings? A new study led by Ezekiel Silverstein (University of Michigan) has addressed this question by exploring DLRGs living in dense galaxy-cluster environments.Projected density of DLRGcentral galaxy matches (black) compared to a control sample of random positionscentral galaxy matches (red) for different distances from acluster center. DLRGs have a higher likelihood of being located close to a cluster center. [Silverstein et al. 2018]Living Near the HubTo build a sample of DLRGs in dense environments, Silverstein and collaborators started from a large catalog of DLRGs in Sloan Digital Sky Survey quasars with radio lobes visible in Very Large Array data. They then cross-matched these against three galaxy catalogs to produce a sample of 44 DLRGs that are each paired to a nearby massive galaxy, galaxy group

  17. Noradrenergic Modulation of Fear Conditioning and Extinction.

    Science.gov (United States)

    Giustino, Thomas F; Maren, Stephen

    2018-01-01

    The locus coeruleus norepinephrine (LC-NE) system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning) the locus coeruleus (LC) promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC) might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC) which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP). Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

  18. Late Pennsylvanian climate changes and palynomorph extinctions

    Energy Technology Data Exchange (ETDEWEB)

    Kosanke, R.M.; Cecil, C.B. [US Geological Survey, Denver, CO (United States)

    1996-01-01

    A major floral change occurs in the Upper Pennsylvanian strata in the Midcontinent, Illinois basin, and in the northern Appalachian basin of eastern United States. Lycospora spp. (derived from arborescent lycopsids) became extinct along with some other palynomorph taxa. This investigation is concerned with the importance of this major floral change. Samples were studied from western Pennsylvania, eastern Ohio, and West Virgina (from a previous study) cover the stratigraphic interval from the Upper Freeport coal bed, uppermost part of the Allegheny Formation, to the Mahoning, Mason, Brush Creek, Wilgus, and Anderson coal beds in the lower part of the Conemaugh Formation. The floral change occurs either at or below the accepted Desmoinesian-Missourian boundary in the Midcontinent and Illinois basin, whereas in the northern Appalachians this change occurs in the lower part of the Conemaugh Formation, between the Mahoning and Brush Creek coal beds, or when the Mason is present, between the Mahoning and Mason coal beds. The first coal bed above the extinction of Lycospora spp. is dominated by the palynomorph taxon Endosporites globiformis which is derived from a heterosporous, herbaceous lycopsid. However, Sigillaria, another arborescent lycopsid, did not become extinct at this time as evidenced by the presence of the palynomorph genus Crassispora which is derived from Sigillaria. The reason for the survival of Sigillaria is now known, but it may have been able to adapt, in a limited fashion, to some sort of specialized microenvironment. The ferns, based on palynomorph occurrence, become numerically more important throughout the balance of the Conemaugh Formation, and dominate the Pittsburgh No. 8 and Pomeroy coal beds in the overlying Monogahela Formation.

  19. Fire extinction utilizing carbon dioxide hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Hatakeyama, T.; Aida, E.; Yokomori, T.; Ohmura, R.; Ueda, T. [Keio Univ., Hiyoshi, Kohoku-ku, Yokohama (Japan)

    2008-07-01

    Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because dissociation of the hydrates results in the temperature decrease in the combustion field and the nonflammable gases released from the dissociated hydrates prevent the supply of the oxygen to the combustion field. This paper discussed experiments in which ordinary ice and dry ice were used to evaluate the performance of CO{sub 2} hydrate as a fire extinguishing agent. The paper described the apparatus and procedure for the preparation of CO{sub 2} hydrate crystals. A schematic of the reactor to form CO{sub 2} hydrate and a photograph of CO{sub 2} hydrate crystal formed in the study were also presented. Other illustrations, photographs, and tables that were presented included a schematic diagram of the experimental apparatus used for the flame extinction experiments; a photograph of CO{sub 2} hydrate powder; sequential video graphs of the flame extinction by the supply of CO{sub 2} hydrate crystals to the methanol pool flame and the relevant illustration; and heat of CO{sub 2} hydrate dissociation, water vaporization and sublimation of dry ice. It was concluded that the critical mass of the CO{sub 2} hydrate required to extinguish a flame was much less than that of ordinary ice, indicating the superiority of CO{sub 2} hydrate to the ice. In addition, the experiments also revealed that the size of the CO{sub 2} hydrate particles had a significant effect on the performance of flame extinction. 5 refs., 2 tabs., 7 figs.

  20. Noradrenergic Modulation of Fear Conditioning and Extinction

    Directory of Open Access Journals (Sweden)

    Thomas F. Giustino

    2018-03-01

    Full Text Available The locus coeruleus norepinephrine (LC-NE system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning the locus coeruleus (LC promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP. Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

  1. Rho Ophiuchi Cloud Core Extinction Map

    Science.gov (United States)

    Gibson, D. J.; Rudolph, A.; Barsony, M.

    1997-12-01

    We present an extinction map of a one square degree region ( ~ 2.2pc square) of the core of the star-forming region rho Ophiuchi derived by the method of star counts. Photometry from the near-infrared J, H, and K band images of Barsony et al. (1997) provided the stellar catalog for this study. From this map an estimate of the mass of the region is made and compared with previous estimates from other methods. Reference Barsony, M., Kenyon, S.J., Lada, E.A., & Teuben, P.J. 1997, ApJS, 112, 109

  2. The risk of extinction - the mutational meltdown or the overpopulation

    OpenAIRE

    Malarz, K.

    2006-01-01

    The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

  3. Variation of the extinction law in the Trifid nebula

    OpenAIRE

    Cambrésy, L.; Rho, J.; Marshall, D. J.; Reach, W. T.

    2011-01-01

    Context. In the past few years, the extinction law has been measured in the infrared wavelengths for various molecular clouds and different laws have been obtained. Aims. In this paper we seek variations of the extinction law within the Trifid nebula region. Such variations would demonstrate local dust evolution linked to variation of the environment parameters such as the density or the interstellar radiation field. Methods. The extinction values, A_λ/A_v, are obtained using the 2MASS, UKIDS...

  4. Dynamics of Population on the Verge of Extinction

    OpenAIRE

    Oborny, B.; Meszena, G.; Szabo, G.

    2005-01-01

    Theoretical considerations suggest that extinction in dispersal-limited populations is necessarily a threshold-like process that is analogous to a critical phase transition in physics. We use this analogy to find robust, common features in the dynamics of extinctions, and suggest early warning signals which may indicate that a population is endangered. As the critical threshold of extinction is approached, the population spontaneously fragments into discrete subpopulations and, consequently, ...

  5. Extinction and dust properties in a clumpy medium

    OpenAIRE

    Scicluna, P.; Siebenmorgen, R.

    2015-01-01

    (abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered photons, resulting in a change in the observed (or effective) extinction, depending on the spatial distribution of the dust and the resolution of the instrument. We investigate the influence of clumpy dust distributions on effective extinction toward embed...

  6. Effects of overtraining on extinction in newts (Cynops pyrrhogaster)

    OpenAIRE

    Shibasaki, Masahiro; Ishida, Masato

    2012-01-01

    The overtraining extinction effect (OEE), a phenomenon in which extended training facilitates extinction, has been found in mammals and reptiles. However, fish have never shown OEE. No study has yet investigated OEE in newts, a representative amphibian species. We tested whether newts, Cynops pyrrhogaster, show OEE in a straight-array task. All animals received five trials per day and were given a piece of dried worm during reinforced trials. They showed significant acquisition and extinction...

  7. Psychological and neural mechanisms of experimental extinction: a selective review.

    Science.gov (United States)

    Delamater, Andrew R; Westbrook, R Frederick

    2014-02-01

    The present review examines key psychological concepts in the study of experimental extinction and implications these have for an understanding of the underlying neurobiology of extinction learning. We suggest that many of the signature characteristics of extinction learning (spontaneous recovery, renewal, reinstatement, rapid reacquisition) can be accommodated by the standard associative learning theory assumption that extinction results in partial erasure of the original learning together with new inhibitory learning. Moreover, we consider recent behavioral and neural evidence that supports the partial erasure view of extinction, but also note shortcomings in our understanding of extinction circuits as these relate to the negative prediction error concept. Recent work suggests that common prediction error and stimulus-specific prediction error terms both may be required to explain neural plasticity both in acquisition and extinction learning. In addition, we suggest that many issues in the content of extinction learning have not been fully addressed in current research, but that neurobiological approaches should be especially helpful in addressing such issues. These include questions about the nature of extinction learning (excitatory CS-No US, inhibitory CS-US learning, occasion setting processes), especially as this relates to studies of the micro-circuitry of extinction, as well as its representational content (sensory, motivational, response). An additional understudied problem in extinction research is the role played by attention processes and their underlying neural networks, although some research and theory converge on the idea that extinction is accompanied by attention decrements (i.e., habituation-like processes). Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Unbounded autocatalytic growth on diffusive substrate: The extinction transition

    International Nuclear Information System (INIS)

    Moalem, Sasi; Shnerb, Nadav M.

    2007-01-01

    The effect of diffusively correlated spatial fluctuations on the proliferation-extinction transition of autocatalytic agents is investigated numerically. Reactants adaptation to spatio-temporal active regions is shown to lead to proliferation even if the mean field rate equations predict extinction, in agreement with previous theoretical predictions. While in the proliferation phase the system admits a typical time scale that dictates the exponential growth, the extinction times distribution obeys a power law at the parameter region considered

  9. Fear extinction requires infralimbic cortex projections to the basolateral amygdala.

    Science.gov (United States)

    Bloodgood, Daniel W; Sugam, Jonathan A; Holmes, Andrew; Kash, Thomas L

    2018-03-06

    Fear extinction involves the formation of a new memory trace that attenuates fear responses to a conditioned aversive memory, and extinction impairments are implicated in trauma- and stress-related disorders. Previous studies in rodents have found that the infralimbic prefrontal cortex (IL) and its glutamatergic projections to the basolateral amygdala (BLA) and basomedial amygdala (BMA) instruct the formation of fear extinction memories. However, it is unclear whether these pathways are exclusively involved in extinction, or whether other major targets of the IL, such as the nucleus accumbens (NAc) also play a role. To address this outstanding issue, the current study employed a combination of electrophysiological and chemogenetic approaches in mice to interrogate the role of IL-BLA and IL-NAc pathways in extinction. Specifically, we used patch-clamp electrophysiology coupled with retrograde tracing to examine changes in neuronal activity of the IL and prelimbic cortex (PL) projections to both the BLA and NAc following fear extinction. We found that extinction produced a significant increase in the intrinsic excitability of IL-BLA projection neurons, while extinction appeared to reverse fear-induced changes in IL-NAc projection neurons. To establish a causal counterpart to these observations, we then used a pathway-specific Designer Receptors Exclusively Activated by Designer Drugs (DREADD) strategy to selectively inhibit PFC-BLA projection neurons during extinction acquisition. Using this approach, we found that DREADD-mediated inhibition of PFC-BLA neurons during extinction acquisition impaired subsequent extinction retrieval. Taken together, our findings provide further evidence for a critical contribution of the IL-BLA neural circuit to fear extinction.

  10. Glutamatergic Targets for Enhancing Extinction Learning in Drug Addiction

    OpenAIRE

    Cleva, R.M; Gass, J.T; Widholm, J.J; Olive, M.F

    2010-01-01

    The persistence of the motivational salience of drug-related environmental cues and contexts is one of the most problematic obstacles to successful treatment of drug addiction. Behavioral approaches to extinguishing the salience of drug-associated cues, such as cue exposure therapy, have generally produced disappointing results which have been attributed to, among other things, the context specificity of extinction and inadequate consolidation of extinction learning. Extinction of any behavio...

  11. The risk of extinction - the mutational meltdown or the overpopulation.

    Science.gov (United States)

    Malarz, Krzysztof

    2007-04-01

    The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

  12. Geographies of Conservation I: De-extinction and Precision Conservation

    OpenAIRE

    Adams, William Mark

    2016-01-01

    Extinction has long been a central concern in biodiversity conservation. Today, de-extinction offers interesting possibilities of restoring charismatic species and ecosystem function, but also risks and costs. Most de-extinction depends on genetic engineering and synthetic biology. These technologies are also proposed for use in ‘gene tweaking’ in wild species to enhance their chance of survival. Within conservation, the resulting debates pit an optimistic world of high-tech ‘precision con...

  13. Precision Photometric Extinction Corrections from Direct Atmospheric Measurements

    Science.gov (United States)

    McGraw, John T.; Zimmer, P.; Linford, J.; Simon, T.; Measurement Astrophysics Research Group

    2009-01-01

    For decades astronomical extinction corrections have been accomplished using nightly mean extinction coefficients derived from Langley plots measured with the same telescope used for photometry. Because this technique results in lost time on program fields, observers only grudgingly made sporadic extinction measurements. Occasionally extinction corrections are not measured nightly but are made using tabulated mean monthly or even quarterly extinction coefficients. Any observer of the sky knows that Earth's atmosphere is an ever-changing fluid in which is embedded extinction sources ranging from Rayleigh (molecular) scattering to aerosol, smoke and dust scattering and absorption, to "just plain cloudy.” Our eyes also tell us that the type, direction and degree of extinction changes on time scales of minutes or less - typically shorter than many astronomical observations. Thus, we should expect that atmospheric extinction can change significantly during a single observation. Mean extinction coefficients might be well-defined nightly means, but those means have high variance because they do not accurately record the wavelength-, time-, and angle-dependent extinction actually affecting each observation. Our research group is implementing lidar measurements made in the direction of observation with one minute cadence, from which the absolute monochromatic extinction can be measured. Simultaneous spectrophotometry of nearby bright standard stars allows derivation and MODTRAN modeling atmospheric transmission as a function of wavelength for the atmosphere through which an observation is made. Application of this technique is demonstrated. Accurate real-time extinction measurements are an enabling factor for sub-1% photometry. This research is supported by NSF Grant 0421087 and AFRL Grant #FA9451-04-2-0355.

  14. Late Quaternary extinctions: The promise of TAMS 14C dating

    International Nuclear Information System (INIS)

    Martin, P.S.

    1987-01-01

    In the last 30 000 years late Quaternary extinctions eliminated over two-thirds of the large land mammals of America and Australia and most of the endemic land vertebrates on oceanic islands. Specimens of extinct animals yielding too little organic material for measurement in decay counters are suitable for TAMS dating. Initial results support older evidence of an extinction chronology that was catastrophic regionally, transgressive globally, and linked to the spread of prehistoric people. (orig.)

  15. Compound stimulus extinction reduces spontaneous recovery in humans

    OpenAIRE

    Coelho, Cesar A.O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

    2015-01-01

    Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design (“deepened extinction”) shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Reco...

  16. The Effect of Size and Ecology on Extinction Susceptibility

    Science.gov (United States)

    Huynh, C.; Yuan, A.; Heim, N.; Payne, J.

    2015-12-01

    Although life on Earth first emerged as prokaryotic organisms, it eventually evolved into billions of different species. However, extinctions on Earth, especially the five mass extinctions, have decimated species. So what leads to a species survival or demise during a mass extinction? Are certain species more susceptible to extinctions based on their size and ecology? For this project, we focused on the data of marine animals. To examine the impact of size and ecology on a species's likelihood of survival, we compared the sizes and ecologies of the survivors and victims of the five mass extinctions. The ecology, or life mode, of a genus consists of the combination of tiering, motility, and feeding mechanism. Tiering refers to the animal's typical location in the water column and sediments, motility refers to its ability to move, and feeding mechanism describes the way the organism eats; together, they describe the animal's behavior. We analyzed the effect of ecology on survival using logistic regression, which compares life mode to the success or failure of a genus during each mass extinction interval. For organism size, we found the extinct organisms' mean size (both volume and length) and compared it with the average size of survivors on a graph. Our results show that while surviving genera of mass extinctions tended to be slightly larger than those that went extinct, there was no significant difference. Even though the Permian (Changhsingian) and Triassic (Rhaetian) extinctions had larger surviving species, likewise the difference was small. Ecology had a more obvious impact on the likelihood of survival; fast-moving, predatory pelagic organisms were the most likely to go extinct, while sedentary, infaunal suspension feeders had the greatest chances of survival. Overall, ecology played a greater role than size in determining the survival of a species. With this information, we can use ecology to predict which species would survive future extinctions.

  17. A multimaterial electrohydrodynamic jet (E-jet) printing system

    International Nuclear Information System (INIS)

    Sutanto, E; Shigeta, K; Kim, Y K; Graf, P G; Hoelzle, D J; Barton, K L; Alleyne, A G; Ferreira, P M; Rogers, J A

    2012-01-01

    Electrohydrodynamic jet (E-jet) printing has emerged as a high-resolution alternative to other forms of direct solution-based fabrication approaches, such as ink-jet printing. This paper discusses the design, integration and operation of a unique E-jet printing platform. The uniqueness lies in the ability to utilize multiple materials in the same overall print-head, thereby enabling increased degrees of heterogeneous integration of different functionalities on a single substrate. By utilizing multiple individual print-heads, with a carrousel indexing among them, increased material flexibility is achieved. The hardware design and system operation for a relatively inexpensive system are developed and presented. Crossover interconnects and multiple fluorescent tagged proteins, demonstrating printed electronics and biological sensing applications, respectively. (paper)

  18. Particle distributions in ordered jets

    International Nuclear Information System (INIS)

    Zarmi, Y.; Kogan, E.

    1978-01-01

    Assuming specific assumptions about the space-time evolution of hadronic jets, within the framework of a Monte-Carlo calculation, the transverse and longitudinal momentum distributins of particles within the jets are obtained. The transverse momentum distributions are sensitive to the space-time evolution picture. The observed energy dependence of the average transverse momentum and the well known seagull effect are qualitatively reproduced within a picture in which Slow particles in a jet are produced First, and Fast ones - Last (SFFL). (author)

  19. Jet substructure with analytical methods

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Mrinal [University of Manchester, Consortium for Fundamental Physics, School of Physics and Astronomy, Manchester (United Kingdom); Fregoso, Alessandro; Powling, Alexander [University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); Marzani, Simone [Durham University, Institute for Particle Physics Phenomenology, Durham (United Kingdom)

    2013-11-15

    We consider the mass distribution of QCD jets after the application of jet-substructure methods, specifically the mass-drop tagger, pruning, trimming and their variants. In contrast to most current studies employing Monte Carlo methods, we carry out analytical calculations at the next-to-leading order level, which are sufficient to extract the dominant logarithmic behaviour for each technique, and compare our findings to exact fixed-order results. Our results should ultimately lead to a better understanding of these jet-substructure methods which in turn will influence the development of future substructure tools for LHC phenomenology. (orig.)

  20. Jet Joint Undertaking. Vol. 2

    International Nuclear Information System (INIS)

    1989-06-01

    The scientific, technical, experimental and theoretical investigations related to JET tokamak are presented. The JET Joint Undertaking, Volume 2, includes papers presented at: the 15th European Conference on controlled fusion and plasma heating, the 15th Symposium on fusion technology, the 12th IAEA Conference on plasma physics and controlled nuclear fusion research, the 8th Topical Meeting on technology of fusion. Moreover, the following topics, concerning JET, are discussed: experience with wall materials, plasma performance, high power ion cyclotron resonance heating, plasma boundary, results and prospects for fusion, preparation for D-T operation, active gas handling system and remote handling equipment

  1. Jet Joint Undertaking. Progress report 1990

    International Nuclear Information System (INIS)

    1991-03-01

    This JET Progress Reports provides an overview summary and puts into context the scientific and technical advances made on JET during 1990. In addition, the Report is supplemented by appendices of contributions (in preprint form) of the more important JET articles published during the year, which set out the details of JET activities

  2. Extinction in the Galaxy from surface brightnesses of ESO-LV galaxies : Testing "standard" extinction maps

    NARCIS (Netherlands)

    Choloniewski, J.; Valentijn, E. A.

    A new method for the determination of the extinction in the Galaxy is proposed. The method uses surface brightnesses of external galaxies in the B and R-bands. The observational data have been taken from the ESO-LV galaxy catalog. As a first application of our model we derive the ratio of R-band to

  3. Jet reconstruction and heavy jet tagging at LHCb

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    The jet reconstruction and the heavy jet flavour tagging at LHCb will be discussed with focus on the last published measurements such as the measurement of forward tt, W+bb and W+cc production in pp collisions at √s=8 TeV and the search for the SM Higgs boson decaying in bbbar or ccbar in association to W or Z boson.

  4. Annular Impinging Jet Controlled by Radial Synthetic Jets

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Tesař, Václav; Broučková, Zuzana; Peszyński, K.

    2014-01-01

    Roč. 35, 16-17 (2014), s. 1450-1461 ISSN 0145-7632 R&D Projects: GA ČR GA14-08888S; GA AV ČR(CZ) IAA200760801 Institutional support: RVO:61388998 Keywords : impinging jet * hybrid synthetic jet * flow control Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts Impact factor: 0.814, year: 2014 http://dx.doi.org/10.1080/01457632.2014.889467

  5. On the trap of extinction and its elimination

    International Nuclear Information System (INIS)

    Vitanov, Nikolay K.; Dimitrova, Zlatinka I.; Kantz, Holger

    2006-01-01

    We investigate the dynamics of a system of three interacting populations in presence of extinction and substitution: each population whose number of individuals drops under some threshold value becomes extinct, and it is substituted by another population with different fitness and different coefficients of interaction with the other populations. We study the influence of extinction on the system states, which in the absence of extinction can be fixed points, limit cycles or chaotic attractors of Shilnikov kind. The extinction can destabilize each of these states. We observe two possible kinds of evolution in the destabilized system: (i) it can remain forever in the trap of extinction, i.e., the extinctions and substitutions of populations continue for indefinitely long time or (ii) it can avoid the trap of extinction by means of the substitution, i.e., the fitness and the coefficients of the interactions between the species move the system attractor away from the zone of the threshold values, the extinction stops, and the system settles on a new attractor. The obtained results are discussed from the point of view of products competing for the preference of buyers that can change their opinion

  6. Brain structural connectivity and context-dependent extinction memory.

    Science.gov (United States)

    Hermann, Andrea; Stark, Rudolf; Blecker, Carlo R; Milad, Mohammed R; Merz, Christian J

    2017-08-01

    Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity. Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later. Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum. Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders. © 2017 Wiley Periodicals, Inc.

  7. Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

    Directory of Open Access Journals (Sweden)

    Sarah Boukezzi

    2017-06-01

    Full Text Available Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD. Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS during eye movement desensitization and reprocessing (EMDR therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations as well as psychophysiological measures (skin conductance responses, SCRs were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR.

  8. Experience with dynamic reinforcement rates decreases resistance to extinction.

    Science.gov (United States)

    Craig, Andrew R; Shahan, Timothy A

    2016-03-01

    The ability of organisms to detect reinforcer-rate changes in choice preparations is positively related to two factors: the magnitude of the change in rate and the frequency with which rates change. Gallistel (2012) suggested similar rate-detection processes are responsible for decreases in responding during operant extinction. Although effects of magnitude of change in reinforcer rate on resistance to extinction are well known (e.g., the partial-reinforcement-extinction effect), effects of frequency of changes in rate prior to extinction are unknown. Thus, the present experiments examined whether frequency of changes in baseline reinforcer rates impacts resistance to extinction. Pigeons pecked keys for variable-interval food under conditions where reinforcer rates were stable and where they changed within and between sessions. Overall reinforcer rates between conditions were controlled. In Experiment 1, resistance to extinction was lower following exposure to dynamic reinforcement schedules than to static schedules. Experiment 2 showed that resistance to presession feeding, a disruptor that should not involve change-detection processes, was unaffected by baseline-schedule dynamics. These findings are consistent with the suggestion that change detection contributes to extinction. We discuss implications of change-detection processes for extinction of simple and discriminated operant behavior and relate these processes to the behavioral-momentum based approach to understanding extinction. © 2016 Society for the Experimental Analysis of Behavior.

  9. Has the Earth's sixth mass extinction already arrived?

    Science.gov (United States)

    Barnosky, Anthony D; Matzke, Nicholas; Tomiya, Susumu; Wogan, Guinevere O U; Swartz, Brian; Quental, Tiago B; Marshall, Charles; McGuire, Jenny L; Lindsey, Emily L; Maguire, Kaitlin C; Mersey, Ben; Ferrer, Elizabeth A

    2011-03-03

    Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

  10. Spatially Synchronous Extinction of Species under External Forcing

    Science.gov (United States)

    Amritkar, R. E.; Rangarajan, Govindan

    2006-06-01

    More than 99% of the species that ever existed on the surface of the Earth are now extinct and their extinction on a global scale has been a puzzle. One may think that a species under an external threat may survive in some isolated locations leading to the revival of the species. Using a general model we show that, under a common external forcing, the species with a quadratic saturation term first undergoes spatial synchronization and then extinction. The effect can be observed even when the external forcing acts only on some locations provided the dynamics contains a synchronizing term. Absence of the quadratic saturation term can help the species to avoid extinction.

  11. Variation in extinction risk among birds: chance or evolutionary predisposition?

    Science.gov (United States)

    Bennett, P. M.; Owens, I. P. F.

    1997-01-01

    Collar et al. (1994) estimate that of the 9,672 extant species of bird, 1,111 are threatened by extinction. Here, we test whether these threatened species are simply a random sample of birds, or whether there is something about their biology that predisposes them to extinction. We ask three specific questions. First, is extinction risk randomly distributed among families? Second, which families, if any, contain more, or less, threatened species than would be expected by chance? Third, is variation between taxa in extinction risk associated with variation in either body size or fecundity? Extinction risk is not randomly distributed among families. The families which contain significantly more threatened species than expected are the parrots (Psittacidae), pheasants and allies (Phasianidae), albatrosses and allies (Procellariidae), rails (Rallidae), cranes (Gruidae), cracids (Cracidae), megapodes (Megapodidae) and pigeons (Columbidae). The only family which contains significantly fewer threatened species than expected is the woodpeckers (Picidae). Extinction risk is also not distributed randomly with respect to fecundity or body size. Once phylogeny has been controlled for, increases in extinction risk are independently associated with increases in body size and decreases in fecundity. We suggest that this is because low rates of fecundity, which evolved many tens of millions of years ago, predisposed certain lineages to extinction. Low-fecundity populations take longer to recover if they are reduced to small sizes and are, therefore, more likely to go extinct if an external force causes an increase in the rate of mortality, thereby perturbing the natural balance between fecundity and mortality.

  12. Extinction of Learned Fear Induces Hippocampal Place Cell Remapping

    Science.gov (United States)

    Wang, Melissa E.; Yuan, Robin K.; Keinath, Alexander T.; Ramos Álvarez, Manuel M.

    2015-01-01

    The extinction of learned fear is a hippocampus-dependent process thought to embody new learning rather than erasure of the original fear memory, although it is unknown how these competing contextual memories are represented in the hippocampus. We previously demonstrated that contextual fear conditioning results in hippocampal place cell remapping and long-term stabilization of novel representations. Here we report that extinction learning also induces place cell remapping in C57BL/6 mice. Specifically, we observed cells that preferentially remapped during different stages of learning. While some cells remapped in both fear conditioning and extinction, others responded predominantly during extinction, which may serve to modify previous representations as well as encode new safe associations. Additionally, we found cells that remapped primarily during fear conditioning, which could facilitate reacquisition of the original fear association. Moreover, we also observed cells that were stable throughout learning, which may serve to encode the static aspects of the environment. The short-term remapping observed during extinction was not found in animals that did not undergo fear conditioning, or when extinction was conducted outside of the conditioning context. Finally, conditioning and extinction produced an increase in spike phase locking to the theta and gamma frequencies. However, the degree of remapping seen during conditioning and extinction only correlated with gamma synchronization. Our results suggest that the extinction learning is a complex process that involves both modification of pre-existing memories and formation of new ones, and these traces coexist within the same hippocampal representation. PMID:26085635

  13. Genetic disruptions of Drosophila Pavlovian learning leave extinction learning intact.

    Science.gov (United States)

    Qin, H; Dubnau, J

    2010-03-01

    Individuals who experience traumatic events may develop persistent posttraumatic stress disorder. Patients with this disorder are commonly treated with exposure therapy, which has had limited long-term success. In experimental neurobiology, fear extinction is a model for exposure therapy. In this behavioral paradigm, animals are repeatedly exposed in a safe environment to the fearful stimulus, which leads to greatly reduced fear. Studying animal models of extinction already has lead to better therapeutic strategies and development of new candidate drugs. Lack of a powerful genetic model of extinction, however, has limited progress in identifying underlying molecular and genetic factors. In this study, we established a robust behavioral paradigm to study the short-term effect (acquisition) of extinction in Drosophila melanogaster. We focused on the extinction of olfactory aversive 1-day memory with a task that has been the main workhorse for genetics of memory in flies. Using this paradigm, we show that extinction can inhibit each of two genetically distinct forms of consolidated memory. We then used a series of single-gene mutants with known impact on associative learning to examine the effects on extinction. We find that extinction is intact in each of these mutants, suggesting that extinction learning relies on different molecular mechanisms than does Pavlovian learning.

  14. Characteristics and generation of secondary jets and secondary gigantic jets

    Science.gov (United States)

    Lee, Li-Jou; Huang, Sung-Ming; Chou, Jung-Kung; Kuo, Cheng-Ling; Chen, Alfred B.; Su, Han-Tzong; Hsu, Rue-Rou; Frey, Harald U.; Takahashi, Yukihiro; Lee, Lou-Chuang

    2012-06-01

    Secondary transient luminous events (TLEs) recorded by the ISUAL-FORMOSAT2 mission can either be secondary jets or secondary gigantic jets (GJs), depending on their terminal altitudes. The secondary jets emerge from the cloud top beneath the preceding sprites and extend upward to the base of the sprites at ˜50 km. The secondary jets likely are negative electric discharges with vertically straight luminous columns, morphologically resembling the trailing jet of the type-I GJs. The number of luminous columns in a secondary jet seems to be affected by the size of the effective capacitor plate formed near the base of the preceding sprites and the charge distribution left behind by the sprite-inducing positive cloud-to-ground discharges. The secondary GJs originate from the cloud top under the shielding area of the preceding sprites, and develop upward to reach the lower ionosphere at ˜90 km. The observed morphology of the secondary GJs can either be the curvy shifted secondary GJs extending outside the region occupied by the preceding sprites or the straight pop-through secondary GJs developing through the center of the preceding circular sprites. A key factor in determining the terminal height of the secondary TLEs appears to be the local ionosphere boundary height that established by the preceding sprites. The abundance and the distribution of the negative charge in the thundercloud following the sprite-inducing positive cloud-to-ground discharges may play important role in the generation of the secondary TLEs.

  15. Blow-off characteristics of turbulent premixed flames in curved-wall Jet Burner

    KAUST Repository

    Mansour, Morkous S.

    2015-08-02

    This study concerns the flame dynamics of a curved-wall jet (CWJ) stabilized turbulent premixed flame as it approaches blow-off conditions. Time resolved OH planar laser-induced fluorescence (PLIF) delineated reaction zone contours and simultaneously stereoscopic particle image velocimetry (SPIV) quantified the turbulent flow field features. Ethylene/air flames were stabilized in CWJ burner to determine the sequence of events leading to blowoff. For stably burning flames far from blowoff, flames are characterized with a recirculation zone (RZ) upstream for flame stabilization followed by an intense turbulent interaction jet (IJ) and merged-jet regions downstream; the flame front counterparts the shear layer vortices. Near blowoff, as the velocity of reactants increases, high local stretch rates exceed the extinction stretch rates instantaneously resulting in localized flame extinction along the IJ region. As Reynolds number (Re) increases, flames become shorter and are entrained by larger amounts of cold reactants. The increased strain rates together with heat loss effects result in further fragmentation of the flame, eventually leading to the complete quenching of the flame. This is explained in terms of local turbulent Karlovitz stretch factor (K) and principal flow strain rates associated with C contours. Hydrogen addition and increasing the RZ size lessen the tendency of flames to be locally extinguished.

  16. Featured Image: Extinction in Our Inner Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2017-11-01

    In this map of the innermost galaxy, which spans only a few square degrees at the Milky Ways center, we can seethe locations of more than 31 million objects obtained from the VISTA Variables in the Va Lctea (VVV) survey. This near-infrared atlas traces stellar populations in the inner Milky Way that are dimmed and reddened by interstellar dust and gas a process known as extinction in a predictable way. Led by Javier Alonso-Garca (University of Antofagasta and the Millennium Institute of Astrophysics in Chile), a team of scientists has now used the VVV measurements of these stars to better understand the distribution of gas and dust that causes extinction in our inner galaxy particularly in the most central, highly reddened, and crowded areas of the Milky Way. For more information, check out the paper below.CitationJavier Alonso-Garca et al 2017 ApJL 849 L13. doi:10.3847/2041-8213/aa92c3

  17. Dinosaur extinction: closing the '3 m gap'.

    Science.gov (United States)

    Lyson, Tyler R; Bercovici, Antoine; Chester, Stephen G B; Sargis, Eric J; Pearson, Dean; Joyce, Walter G

    2011-12-23

    Modern debate regarding the extinction of non-avian dinosaurs was ignited by the publication of the Cretaceous-Tertiary (K-T) asteroid impact theory and has seen 30 years of dispute over the position of the stratigraphically youngest in situ dinosaur. A zone devoid of dinosaur fossils reported from the last 3 m of the Upper Cretaceous, coined the '3 m gap', has helped drive controversy. Here, we report the discovery of the stratigraphically youngest in situ dinosaur specimen: a ceratopsian brow horn found in a poorly rooted, silty, mudstone floodplain deposit located no more than 13 cm below the palynologically defined boundary. The K-T boundary is identified using three criteria: (i) decrease in Cretaceous palynomorphs without subsequent recovery, (ii) the existence of a 'fern spike', and (iii) correlation to a nearby stratigraphic section where primary extraterrestrial impact markers are present (e.g. iridium anomaly, spherules, shocked quartz). The in situ specimen demonstrates that a gap devoid of non-avian dinosaur fossils does not exist and is inconsistent with the hypothesis that non-avian dinosaurs were extinct prior to the K-T boundary impact event.

  18. Equatorial jet - a case study

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; PrasannaKumar, S.

    analysis of hydrographic data of 1964 is also carried out to understand the response signature of water column to prevailing westerlies. A jet forms in the Central Indian Ocean which gathers momentum as it advances eastward. Sinking of the thermocline...

  19. Jets in heavy ion collisions

    International Nuclear Information System (INIS)

    Nattrass, Christine

    2017-01-01

    High energy collisions of heavy nuclei permit the study of nuclear matter at temperatures and energy densities so high that the fundamental theory for strong interactions, QCD, predicts a phase transition to a plasma of quarks and gluons. This matter, called a Quark Gluon Plasma (QGP), has been studied experimentally for the last decade and has been observed to be a strongly interacting liquid with a low viscosity. High energy partons created early in the collision interact with the QGP and provide unique probes of its properties. Hard partons fragment into collimated sprays of particles called jets and have been studied through measurements of single particles, correlations between particles, and measurements of fully reconstructed jets. These measurements demonstrate partonic energy loss in the QGP and constrain the QGP’s properties. Measurements of the jet structure give insight into the mechanism of this energy loss. The information we have learned from studies of jets and challenges for the field will be reviewed. (paper)

  20. Jet-quenching and correlations

    Indian Academy of Sciences (India)

    2015-05-06

    May 6, 2015 ... pseudorapidity (ridge) correlations in small systems. Section 7 ... words of 'jet' and 'parton' are often used interchangeably. ...... [118] STAR Collaboration: Joshua Konzer, Poster presentation at Quark Matter 2012 (2012).

  1. Jet calculus beyond leading logarithms

    International Nuclear Information System (INIS)

    Kalinowski, J.; Konishi, K.; Taylor, T.R.

    1981-01-01

    It is shown that the evolution of hadronic jets produced in hard processes can be studied in terms of a simple parton branching picture, beyond the leading log approximation of QCD. The jet calculus is generalized to any given order of logs (but always to all orders of αsub(s)). We discuss the general structure of the formalism. Universality of jet evolution is discussed. We consider also a jet calorimetry measure and the multiplicity distribution of final states in a form which allows a systematic improvement of approximation. To the next-to-leading order, we prove the finiteness and elucidate the scheme dependence of parton subprocess probabilities. The physical inclusive cross section is shown to be scheme independent: next-to-leading results for e + e - → q (nonsinglet) + X agree with those of Curci and others. (orig.)

  2. Jets in deep inelastic scattering

    International Nuclear Information System (INIS)

    Joensson, L.

    1995-01-01

    Jet production in deep inelastic scattering provides a basis for the investigation of various phenomena related to QCD. Two-jet production at large Q 2 has been studied and the distributions with respect to the partonic scaling variables have been compared to models and to next to leading order calculations. The first observations of azimuthal asymmetries of jets produced in first order α s processes have been obtained. The gluon initiated boson-gluon fusion process permits a direct determination of the gluon density of the proton from an analysis of the jets produced in the hard scattering process. A comparison of these results with those from indirect extractions of the gluon density provides an important test of QCD. (author)

  3. The JET multi-camera soft X-ray diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Alper, B; Blackler, K; Dillon, S F; Edwards, A W; Gill, R D; Lyadina, E; Mulligan, W; Staunton-Lambert, S A.B.; Thompson, D G; Wilson, D J [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    A new soft X-ray detector system has been constructed for the pumped divertor phase of JET which incorporates a number of enhancements over the previous system in both hardware and data acquisition. The hardware improvements include: six independent views of the plasma at one toroidal location (as opposed to two in the old system), spatial resolution improved from 7 cm to 3 cm, frequency response increased from 30 khz to 100 khz and improved toroidal mode resolution. These enhancements will allow the study of MHD activity in finer detail. The tomographic reconstruction of soft X-ray emissivities will be improved to include Fourier terms up to cos(5{theta}) compared with only cos(2{theta}) before. Through the implementation of a fast central acquisition and trigger system, data from a range of diagnostics will be available at high bandwidth to allow processing of plasma phenomena of far greater complexity than was possible before. (authors). 2 refs., 5 figs.

  4. Opposing nodal and BMP signals regulate left-right asymmetry in the sea urchin larva.

    Directory of Open Access Journals (Sweden)

    Yi-Jyun Luo

    Full Text Available Nodal and BMP signals are important for establishing left-right (LR asymmetry in vertebrates. In sea urchins, Nodal signaling prevents the formation of the rudiment on the right side. However, the opposing pathway to Nodal signaling during LR axis establishment is not clear. Here, we revealed that BMP signaling is activated in the left coelomic pouch, specifically in the veg2 lineage, but not in the small micromeres. By perturbing BMP activities, we demonstrated that BMP signaling is required for activating the expression of the left-sided genes and the formation of the left-sided structures. On the other hand, Nodal signals on the right side inhibit BMP signaling and control LR asymmetric separation and apoptosis of the small micromeres. Our findings show that BMP signaling is the positive signal for left-sided development in sea urchins, suggesting that the opposing roles of Nodal and BMP signals in establishing LR asymmetry are conserved in deuterostomes.

  5. Repair of closely opposed cyclobutyl pyrimidine dimers in UV-sensitive human diploid fibroblasts

    International Nuclear Information System (INIS)

    Lam, L.H.; Reynolds, R.J.

    1986-01-01

    An enzyme-sensitive site assay has been used to examine the fate of closely opposed pyrimidine dimers in fibroblasts from individuals afflicted with various genetic disorders that confer increased cellular sensitivity to UV radiation. The disappearance of bifilar enzyme-sensitive sites was found to be normal in cells from individuals with Fanconi's anemia, Cockayne's syndrome, dyskeratosis congenita and the variant form of xeroderma pigmentosum. The rate of bifilar enzyme-sensitive site removal in XP cells assigned to complementation group C was reduced by an amount similar to that observed for the repair of isolated dimers. Our results indicate that the initiation of repair at closely opposed dimers is slow in XP-C cells but normal in all other cells examined. (Auth.)

  6. Top Jets at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, L.G.; Lee, S.J.; Perez, G.; Sung, I.; Virzi, J.

    2008-10-06

    We investigatethe reconstruction of high pT hadronically-decaying top quarksat the Large Hadron Collider. One of the main challenges in identifying energetictop quarks is that the decay products become increasingly collimated. This reducesthe efficacy of conventional reconstruction methods that exploit the topology of thetop quark decay chain. We focus on the cases where the decay products of the topquark are reconstructed as a single jet, a"top-jet." The most basic"top-tag" methodbased on jet mass measurement is considered in detail. To analyze the feasibility ofthe top-tagging method, both theoretical and experimental aspects of the large QCDjet background contribution are examined. Based on a factorization approach, wederive a simple analytic approximation for the shape of the QCD jet mass spectrum.We observe very good agreement with the Monte Carlo simulation. We consider high pT tt bar production in the Standard Model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25 fb-1 of data, our approach allows us to resolve top-jets with pT _> 1 TeV, from the QCD background, and about 1.5 TeV top-jets with 100 fb-1, without relying on b-tagging. To further improve the significancewe consider jet shapes (recently analyzed in 0807.0234 [hep-ph]), which resolve thesubstructure of energy flow inside cone jets. A method of measuring the top quarkpolarization by using the transverse momentum of the bottom quark is also presented.The main advantages of our approach are: (i) the mass distributions are driven byfirst principle calculations, instead of relying solely on Monte Carlo simulation; (ii) for high pT jets (pT _> 1 TeV), IR-safe jet shape variables are robust against detectorresolution effects. Our analysis can be applied to other boosted massive particlessuch as the electroweak gauge bosons and the Higgs.

  7. Centrifuge pellet injector for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buchelt, E.; Jacobi, D.; Lackner, E.; Schilling, H.B.; Ulrich, M.; Weber, G.

    1983-08-01

    An engineering design of a centrifuge pellet injector for JET is reported as part of the Phase I contract number JE 2/9016. A rather detailed design is presented for the mechanical and electronic features. Stress calculations, dynamic behaviour and life estimates are considered. The interfaces to the JET vacuum system and CODAS are discussed. Proposals for the pellet diagnostics (velocity, mass and shape) are presented. (orig.)

  8. 4-jet events at LEP

    CERN Document Server

    Bizouard, M A

    1997-01-01

    Results of a special study made by the four LEP experiments on 4-jet events recorded at Vs = 130 - 136 , 161 and 172 GeV are related. This study concerns the ALEPH analysis which has shown an excess of 4-jet events in data recorded at Vs = 130 - 136 GeV. No significant evidence has been found by the 3 other experiments. Results have been combined after several checks which did not show differences of performance between the four LEP experiments.

  9. Overview of JET results

    International Nuclear Information System (INIS)

    Pamela, J.

    2003-01-01

    Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. The physics of the ITER reference mode of operation, the ELMy H-mode, has progressed significantly: the extrapolation of ELM size to ITER has been re-evaluated; NTMs have been shown to be metastable in JET, and can be avoided via sawtooth destabilisation by ICRH; α-simulation experiments were carried out by accelerating 4 He beam ions by ICRH, providing a new tool for fast particle and MHD studies with up to 80-90% of plasma heating by fast 4 He ions. With or without impurity seeding, quasi-steady sate high confinement (H 98 =1), high density (n e /n GR = 0.9-1) and high β (β N =2) ELMy H-mode has been achieved by operating near the ITER triangularity (δ∼0.40-0.5) and safety factor (q 95 ∼3), at Z eff ∼1.5-2. In Advanced Tokamak scenarios, internal transport barriers are now characterised in real time with a new criterion ρ* T ; tailoring of the current profile with LHCD provides reliable access to a variety of q profiles, with significantly lowered access power for barrier formation; rational q surfaces appear to be associated with ITB formation; Alfven cascades are observed in RS plasmas, providing an identification of q profile evolution; plasmas with 'current holes' were observed and explained by modelling. Transient high confinement Advanced Tokamak regimes with H89=3.3, β N =2.4 and ITER relevant q<5 are achievable in reversed magnetic shear. Quasistationary internal transport barriers are developed with full non-inductive current drive, including ∼50% bootstrap current. Record duration of ITBs was achieved, up to 11 s, approaching the resistive time. Pressure and current profiles of Advanced Tokamak regimes are controlled by a real time feedback system, in separate experiments. The erosion and co-deposition data base progressed significantly, in particular with a new quartz microbalance diagnostic allowing shot by shot measurements of

  10. Development and Experimental Investigation of a Two-Stroke Opposed-Piston Free-Piston Engine

    OpenAIRE

    Schneider, Stephan; Chiodi, Marco; Friedrich, Horst E.; Bargende, Michael

    2016-01-01

    The proposed paper deals with the development process and initial measurement results of an opposed-piston combustion engine for application in a Free-Piston Linear Generator (FPLG). The FPLG, which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for a fuel based electrical power supply. With its arrangement, the pistons freely oscillate between the compression chamber of the combustion unit and a gas spring with no mechanical coupling like...

  11. Research on the Common Rail Pressure Overshoot of Opposed-Piston Two-Stroke Diesel Engines

    OpenAIRE

    Yi Lu; Changlu Zhao; Zhe Zuo; Fujun Zhang; Shuanlu Zhang

    2017-01-01

    The common rail pressure has a direct influence on the working stability of Opposed-Piston Two-Stroke (OP2S) diesel engines, especially on performance indexes such as power, economy and emissions. Meanwhile, the rail pressure overshoot phenomenon occurs frequently due to the operating characteristics of OP2S diesel engines, which could lead to serious consequences. In order to solve the rail pressure overshoot problem of OP2S diesel engines, a nonlinear concerted algorithm adding a speed stat...

  12. Acute stress impairs the retrieval of extinction memory in humans

    Science.gov (United States)

    Raio, Candace M.; Brignoni-Perez, Edith; Goldman, Rachel; Phelps, Elizabeth A.

    2014-01-01

    Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays an important role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent research in rodents found that exposure to stress led to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress responses, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, one day later participants in the stress group (n = 27) demonstrated significantly less

  13. A robust nonparametric method for quantifying undetected extinctions.

    Science.gov (United States)

    Chisholm, Ryan A; Giam, Xingli; Sadanandan, Keren R; Fung, Tak; Rheindt, Frank E

    2016-06-01

    How many species have gone extinct in modern times before being described by science? To answer this question, and thereby get a full assessment of humanity's impact on biodiversity, statistical methods that quantify undetected extinctions are required. Such methods have been developed recently, but they are limited by their reliance on parametric assumptions; specifically, they assume the pools of extant and undetected species decay exponentially, whereas real detection rates vary temporally with survey effort and real extinction rates vary with the waxing and waning of threatening processes. We devised a new, nonparametric method for estimating undetected extinctions. As inputs, the method requires only the first and last date at which each species in an ensemble was recorded. As outputs, the method provides estimates of the proportion of species that have gone extinct, detected, or undetected and, in the special case where the number of undetected extant species in the present day is assumed close to zero, of the absolute number of undetected extinct species. The main assumption of the method is that the per-species extinction rate is independent of whether a species has been detected or not. We applied the method to the resident native bird fauna of Singapore. Of 195 recorded species, 58 (29.7%) have gone extinct in the last 200 years. Our method projected that an additional 9.6 species (95% CI 3.4, 19.8) have gone extinct without first being recorded, implying a true extinction rate of 33.0% (95% CI 31.0%, 36.2%). We provide R code for implementing our method. Because our method does not depend on strong assumptions, we expect it to be broadly useful for quantifying undetected extinctions. © 2016 Society for Conservation Biology.

  14. Climate change, elevational range shifts, and bird extinctions.

    Science.gov (United States)

    Sekercioglu, Cagan H; Schneider, Stephen H; Fay, John P; Loarie, Scott R

    2008-02-01

    Limitations imposed on species ranges by the climatic, ecological, and physiological effects of elevation are important determinants of extinction risk. We modeled the effects of elevational limits on the extinction risk of landbirds, 87% of all bird species. Elevational limitation of range size explained 97% of the variation in the probability of being in a World Conservation Union category of extinction risk. Our model that combined elevational ranges, four Millennium Assessment habitat-loss scenarios, and an intermediate estimate of surface warming of 2.8 degrees C, projected a best guess of 400-550 landbird extinctions, and that approximately 2150 additional species would be at risk of extinction by 2100. For Western Hemisphere landbirds, intermediate extinction estimates based on climate-induced changes in actual distributions ranged from 1.3% (1.1 degrees C warming) to 30.0% (6.4 degrees C warming) of these species. Worldwide, every degree of warming projected a nonlinear increase in bird extinctions of about 100-500 species. Only 21% of the species predicted to become extinct in our scenarios are currently considered threatened with extinction. Different habitat-loss and surface-warming scenarios predicted substantially different futures for landbird species. To improve the precision of climate-induced extinction estimates, there is an urgent need for high-resolution measurements of shifts in the elevational ranges of species. Given the accelerating influence of climate change on species distributions and conservation, using elevational limits in a tested, standardized, and robust manner can improve conservation assessments of terrestrial species and will help identify species that are most vulnerable to global climate change. Our climate-induced extinction estimates are broadly similar to those of bird species at risk from other factors, but these estimates largely involve different sets of species.

  15. 3,4-Methylenedioxymethamphetamine facilitates fear extinction learning.

    Science.gov (United States)

    Young, M B; Andero, R; Ressler, K J; Howell, L L

    2015-09-15

    Acutely administered 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') has been proposed to have long-term positive effects on post-traumatic stress disorder (PTSD) symptoms when combined with psychotherapy. No preclinical data support a mechanistic basis for these claims. Given the persistent nature of psychotherapeutic gains facilitated by MDMA, we hypothesized that MDMA improves fear extinction learning, a key process in exposure-based therapies for PTSD. In these experiments, mice were first exposed to cued fear conditioning and treated with drug vehicle or MDMA before extinction training 2 days later. MDMA was administered systemically and also directly targeted to brain structures known to contribute to extinction. In addition to behavioral measures of extinction, changes in mRNA levels of brain-derived neurotrophic factor (Bdnf) and Fos were measured after MDMA treatment and extinction. MDMA (7.8 mg kg(-1)) persistently and robustly enhanced long-term extinction when administered before extinction training. MDMA increased the expression of Fos in the amygdala and medial prefrontal cortex (mPFC), whereas increases in Bdnf expression were observed only in the amygdala after extinction training. Extinction enhancements were recapitulated when MDMA (1 μg) was infused directly into the basolateral complex of the amygdala (BLA), and enhancement was abolished when BDNF signaling was inhibited before extinction. These findings suggest that MDMA enhances fear memory extinction through a BDNF-dependent mechanism, and that MDMA may be a useful adjunct to exposure-based therapies for PTSD and other anxiety disorders characterized by altered fear learning.

  16. Transverse jets and their control

    Energy Technology Data Exchange (ETDEWEB)

    Karagozian, Ann R. [Department of Mechanical and Aerospace Engineering, University of California, 48-121 Engineering IV, Los Angeles, CA 90095 (United States)

    2010-10-15

    The jet in crossflow or transverse jet has been studied extensively because of its relevance to a wide variety of flows in technological systems, including fuel or dilution air injection in gas turbine engines, thrust vector control for high speed airbreathing and rocket vehicles, and exhaust plumes from power plants. These widespread applications have led over the past 50+ years to experimental, theoretical, and numerical examinations of this fundamental flowfield, with and without a combustion reaction, and with single or multi-phase flow. The complexities in this flowfield, whether the jet is introduced flush with respect to the injection wall or from an elevated pipe or nozzle, present challenges in accurately interrogating, analyzing, and simulating important jet features. This review article provides a background on these studies and applications as well as detailed features of the transverse jet, and mechanisms for its control via active means. Promising future directions for the understanding, interrogation, simulation, and control of transverse jet flows are also identified and discussed. (author)

  17. Why do older people oppose physician-assisted dying? A qualitative study.

    Science.gov (United States)

    Malpas, Phillipa J; Wilson, Maria K R; Rae, Nicola; Johnson, Malcolm

    2014-04-01

    Physician-assisted dying at the end of life has become a significant issue of public discussion. While legally available in a number of countries and jurisdictions, it remains controversial and illegal in New Zealand. The study aimed to explore the reasons some healthy older New Zealanders oppose physician-assisted dying in order to inform current debate. Recorded interviews were transcribed and analysed by the authors after some edits had been made by respondents. In all, 11 older participants (over 65 years) who responded to advertisements placed in Grey Power magazines and a University of Auckland email list were interviewed for around 1 h and asked a number of open-ended questions. Four central themes opposing physician-assisted dying were identified from the interviews: one's personal experience with health care and dying and death, religious reasoning and beliefs, slippery slope worries and concern about potential abuses if physician-assisted dying were legalised. An important finding of the study suggests that how some older individuals think about physician-assisted dying is strongly influenced by their past experiences of dying and death. While some participants had witnessed good, well-managed dying and death experiences which confirmed for them the view that physician-assisted dying was unnecessary, those who had witnessed poor dying and death experiences opposed physician-assisted dying on the grounds that such practices could come to be abused by others.

  18. High rate reactive sputtering in an opposed cathode closed-field unbalanced magnetron sputtering system

    Science.gov (United States)

    Sproul, William D.; Rudnik, Paul J.; Graham, Michael E.; Rohde, Suzanne L.

    1990-01-01

    Attention is given to an opposed cathode sputtering system constructed with the ability to coat parts with a size up to 15 cm in diameter and 30 cm in length. Initial trials with this system revealed very low substrate bias currents. When the AlNiCo magnets in the two opposed cathodes were arranged in a mirrored configuration, the plasma density at the substrate was low, and the substrate bias current density was less than 1 mA/sq cm. If the magnets were arranged in a closed-field configuration where the field lines from one set of magnets were coupled with the other set, the substrate bias current density was as high as 5.7 mA/sq cm when NdFeB magnets were used. In the closed-field configuration, the substrate bias current density was related to the magnetic field strength between the two cathodes and to the sputtering pressure. Hard well-adhered TiN coatings were reactively sputtered in the opposed cathode system in the closed-field configuration, but the mirrored configuration produced films with poor adhesion because of etching problems and low plasma density at the substrate.

  19. Opposing Cholinergic and Serotonergic Modulation of Layer 6 in Prefrontal Cortex

    Directory of Open Access Journals (Sweden)

    Daniel W. Sparks

    2018-01-01

    Full Text Available Prefrontal cortex is a hub for attention processing and receives abundant innervation from cholinergic and serotonergic afferents. A growing body of evidence suggests that acetylcholine (ACh and serotonin (5-HT have opposing influences on tasks requiring attention, but the underlying neurophysiology of their opposition is unclear. One candidate target population is medial prefrontal layer 6 pyramidal neurons, which provide feedback modulation of the thalamus, as well as feed-forward excitation of cortical interneurons. Here, we assess the response of these neurons to ACh and 5-HT using whole cell recordings in acute brain slices from mouse cortex. With application of exogenous agonists, we show that individual layer 6 pyramidal neurons are bidirectionally-modulated, with ACh and 5-HT exerting opposite effects on excitability across a number of concentrations. Next, we tested the responses of layer 6 pyramidal neurons to optogenetic release of endogenous ACh or 5-HT. These experiments were performed in brain slices from transgenic mice expressing channelrhodopsin in either ChAT-expressing cholinergic neurons or Pet1-expressing serotonergic neurons. Light-evoked endogenous neuromodulation recapitulated the effects of exogenous neurotransmitters, showing opposing modulation of layer 6 pyramidal neurons by ACh and 5-HT. Lastly, the addition of 5-HT to either endogenous or exogenous ACh significantly suppressed the excitation of pyramidal neurons in prefrontal layer 6. Taken together, this work suggests that the major corticothalamic layer of prefrontal cortex is a substrate for opposing modulatory influences on neuronal activity that could have implications for regulation of attention.

  20. Opposing Cholinergic and Serotonergic Modulation of Layer 6 in Prefrontal Cortex.

    Science.gov (United States)

    Sparks, Daniel W; Tian, Michael K; Sargin, Derya; Venkatesan, Sridevi; Intson, Katheron; Lambe, Evelyn K

    2017-01-01

    Prefrontal cortex is a hub for attention processing and receives abundant innervation from cholinergic and serotonergic afferents. A growing body of evidence suggests that acetylcholine (ACh) and serotonin (5-HT) have opposing influences on tasks requiring attention, but the underlying neurophysiology of their opposition is unclear. One candidate target population is medial prefrontal layer 6 pyramidal neurons, which provide feedback modulation of the thalamus, as well as feed-forward excitation of cortical interneurons. Here, we assess the response of these neurons to ACh and 5-HT using whole cell recordings in acute brain slices from mouse cortex. With application of exogenous agonists, we show that individual layer 6 pyramidal neurons are bidirectionally-modulated, with ACh and 5-HT exerting opposite effects on excitability across a number of concentrations. Next, we tested the responses of layer 6 pyramidal neurons to optogenetic release of endogenous ACh or 5-HT. These experiments were performed in brain slices from transgenic mice expressing channelrhodopsin in either ChAT-expressing cholinergic neurons or Pet1-expressing serotonergic neurons. Light-evoked endogenous neuromodulation recapitulated the effects of exogenous neurotransmitters, showing opposing modulation of layer 6 pyramidal neurons by ACh and 5-HT. Lastly, the addition of 5-HT to either endogenous or exogenous ACh significantly suppressed the excitation of pyramidal neurons in prefrontal layer 6. Taken together, this work suggests that the major corticothalamic layer of prefrontal cortex is a substrate for opposing modulatory influences on neuronal activity that could have implications for regulation of attention.

  1. Two different approaches for creating a prescribed opposed-flow velocity field for flame spread experiments

    Directory of Open Access Journals (Sweden)

    Carmignani Luca

    2015-01-01

    Full Text Available Opposed-flow flame spread over solid fuels is a fundamental area of research in fire science. Typically combustion wind tunnels are used to generate the opposing flow of oxidizer against which a laminar flame spread occurs along the fuel samples. The spreading flame is generally embedded in a laminar boundary layer, which interacts with the strong buoyancy-induced flow to affect the mechanism of flame spread. In this work, two different approaches for creating the opposed-flow are compared. In the first approach, a vertical combustion tunnel is used where a thin fuel sample, thin acrylic or ashless filter paper, is held vertically along the axis of the test-section with the airflow controlled by controlling the duty cycles of four fans. As the sample is ignited, a flame spreads downward in a steady manner along a developing boundary layer. In the second approach, the sample is held in a movable cart placed in an eight-meter tall vertical chamber filled with air. As the sample is ignited, the cart is moved downward (through a remote-controlled mechanism at a prescribed velocity. The results from the two approaches are compared to establish the boundary layer effect on flame spread over thin fuels.

  2. Serelaxin as a novel therapeutic opposing fibrosis and contraction in lung diseases.

    Science.gov (United States)

    Lam, Maggie; Royce, Simon G; Samuel, Chrishan S; Bourke, Jane E

    2018-07-01

    The most common therapies for asthma and other chronic lung diseases are anti-inflammatory agents and bronchodilators. While these drugs oppose disease symptoms, they do not reverse established structural changes in the airways and their therapeutic efficacy is reduced with increasing disease severity. The peptide hormone, relaxin, is a Relaxin Family Peptide Receptor 1 (RXFP1) receptor agonist with unique combined effects in the lung that differentiates it from these existing therapies. Relaxin has previously been reported to have cardioprotective effects in acute heart failure as well anti-fibrotic actions in several organs. This review focuses on recent experimental evidence of the beneficial effects of chronic relaxin treatment in animal models of airways disease demonstrating inhibition of airway hyperresponsiveness and reversal of established fibrosis, consistent with potential therapeutic benefit. Of particular interest, accumulating evidence demonstrates that relaxin can also acutely oppose contraction by reducing the release of mast cell-derived bronchoconstrictors and by directly eliciting bronchodilation. When used in combination, chronic and acute treatment with relaxin has been shown to enhance responsiveness to both glucocorticoids and β 2 -adrenoceptor agonists respectively. While the mechanisms underlying these beneficial actions remain to be fully elucidated, translation of these promising combined preclinical findings is critical in the development of relaxin as a novel alternative or adjunct therapeutic opposing multiple aspects of airway pathology in lung diseases. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Disruptions in JET

    International Nuclear Information System (INIS)

    Wesson, J.A.; Gill, R.D.; Hugon, M.

    1989-01-01

    In JET, both high density and low-q operation are limited by disruptions. The density limit disruptions are caused initially by impurity radiation. This causes a contraction of the plasma temperature profile and leads to an MHD unstable configuration. There is evidence of magnetic island formation resulting in minor disruptions. After several minor disruptions, a major disruption with a rapid energy quench occurs. This event takes place in two stages. In the first stage there is a loss of energy from the central region. In the second stage there is a more rapid drop to a very low temperature, apparently due to a dramatic increase in impurity radiation. The final current decay takes place in the resulting cold plasma. During the growth of the MHD instability the initially rotating mode is brought to rest. This mode locking is believed to be due to an electromagnetic interaction with the vacuum vessel and external magnetic field asymmetries. The low-q disruptions are remarkable for the precision with which they occur at q ψ = 2. These disruptions do not have extended precursors or minor disruptions. The instability grows and locks rapidly. The energy quench and current decay are generally similar to those of the density limit. (author). 43 refs, 35 figs, 3 tabs

  4. Was it the CO2 or the sulfur that did it? The mechanism of mass extinction of continental vertebrates at the end-Triassic extinction.

    Science.gov (United States)

    Olsen, P. E.; Schaller, M. F.; Kent, D. V.; Et-Touhami, M.

    2012-04-01

    Eruption of the giant Central Atlantic Magmatic Province (CAMP) is temporally linked to the end-Triassic extinction (ETE) event (1,2,3,4,5). Proposed killing mechanisms for plants and marine biota have included both CO2 (4) and sulfur aerosols (3,6). Here we examine the kill mechanisms of the CAMP for land animals where we seek to explain the selectivity of the extinctions. One striking aspect of Late Triassic continental communities is the prominent latitudinal provinciality with diverse crurotarsians (crocodile-relatives) and other non-dinosaurs in the tropics and much higher dinosaur diversity in the higher latitudes (7). Only a very few crurotarsian lineages survived the ETE, and a near-homogenization of continental vertebrate assemblages ensued. Background high CO2 concentration in the Late Triassic resulted in lack of polar ice and probably very high-temperature tropical continental interiors. While a doubling of CO2 associated with CAMP eruptions produced a few degree increase in average temperatures (depending on the sensitivity), plausibly leading to some tropical lethality, how this produced a mass extinction in higher, cooler latitudes is harder to explain. While successive CAMP eruptions contributed to CO2 doublings over hundreds to thousands of years, taking two orders of magnitude longer to return to background, EACH major CAMP eruption produced an abrupt sulfur aerosol cooling lasting several years or decades, depending eruption duration. But there were many of these coolings as opposed to the few super-greenhouse warmings suggested by the CO2 proxy data (4,5). The scale of these sulfur injections would have been orders of magnitude larger than anything seen historically (8) possibly leading to freezing tropical temperatures. Both cruotarsians and dinosaurs as well as most other "reptiles", with their presumably uricotelic nitrogen waste systems (9) were been relatively resistant to heat induced water stress, but the former lack insolation, while the

  5. Deepened Extinction following Compound Stimulus Presentation: Noradrenergic Modulation

    Science.gov (United States)

    Janak, Patricia H.; Corbit, Laura H.

    2011-01-01

    Behavioral extinction is an active form of new learning involving the prediction of nonreward where reward has previously been present. The expression of extinction learning can be disrupted by the presentation of reward itself or reward-predictive stimuli (reinstatement) as well as the passage of time (spontaneous recovery) or contextual changes…

  6. Asymptotic behaviour near extinction of continuous-state branching processes

    OpenAIRE

    Berzunza, Gabriel; Pardo, Juan Carlos

    2016-01-01

    In this note, we study the asymptotic behaviour near extinction of (sub-) critical continuous state branching processes. In particular, we establish an analogue of Khintchin's law of the iterated logarithm near extinction time for a continuous state branching process whose branching mechanism satisfies a given condition and its reflected process at its infimum.

  7. DUST EXTINCTION IN NGC-4594, THE SOMBRERO GALAXY

    NARCIS (Netherlands)

    KNAPEN, JH; HES, R; BECKMAN, JE; PELETIER, RF

    We have studied the extinction law in the well-defined dust lane of the Sombrero galaxy, NGC4594. In the R,I,J,H, and K bands we find good agreement between values for the extinction ratios A-lambda/A(v) in NGC4594 and those reported for our own Galaxy. We can explain the apparently somewhat lower

  8. Ultraviolet extinction in M-supergiant circumstellar envelopes

    International Nuclear Information System (INIS)

    Buss, R.H. Jr.; Snow, T.P. Jr.

    1986-01-01

    Using International Ultraviolet (IUS) archival low-dispersion spectra, ultraviolet spectral extinctions were derived for the circumstellar envelopes of two M supergiants: HD 60414 and HD 213310. The observed stellar systems belong to a class of widely-separated spectroscopic binaries that are called VV Cephei stars. The total extinction was calculated by dividing the reddened fluxes with unreddened comparison fluxes of similar stars (g B2.5 for HD 213310 and a normalized s+B3 for HD 60414) from the reference atlas. After substracting the interstellar extinctions, which were estimated from the E(B-V) reddening of nearby stars, the resultant circumstellar extinctions were normalized at about 3.5 inverse microns. Not only is the 2175 A extinction bump absent in the circumstellar extinctions, but the far-ultraviolet extinction rise is also absent. The rather flat, ultraviolet extinction curves were interpreted as signatures of a population of noncarbonaceous, oxygen-rich grains with diameters larger than the longest observed wavelength

  9. POST-RETRIEVAL EXTINCTION ATTENUATES ALCOHOL CUE REACTIVITY IN RATS

    Science.gov (United States)

    Cofresí, Roberto U.; Lewis, Suzanne M.; Chaudhri, Nadia; Lee, Hongjoo J.; Monfils, Marie-H.; Gonzales, Rueben A.

    2017-01-01

    BACKGROUND Conditioned responses to alcohol-associated cues can hinder recovery from alcohol use disorder (AUD). Cue exposure (extinction) therapy (CET) can reduce reactivity to alcohol cues, but its efficacy is limited by phenomena such as spontaneous recovery and reinstatement that can cause a return of conditioned responding after extinction. Using a preclinical model of alcohol cue reactivity in rats, we evaluated whether the efficacy of alcohol CET could be improved by conducting CET during the memory reconsolidation window after retrieval of a cue-alcohol association. METHODS Rats were provided with intermittent access to unsweetened alcohol. Rats were then trained to predict alcohol access based on a visual cue. Next, rats were treated with either standard extinction (n=14) or post-retrieval extinction (n=13). Rats were then tested for long-term memory of extinction and susceptibility to spontaneous recovery and reinstatement. RESULTS Despite equivalent extinction, rats treated with post-retrieval extinction exhibited reduced spontaneous recovery and reinstatement relative to rats treated with standard extinction. CONCLUSIONS Post-retrieval CET shows promise for persistently attenuating the risk to relapse posed by alcohol cues in individuals with AUD. PMID:28169439

  10. d-Cycloserine reduces context specificity of sexual extinction learning

    NARCIS (Netherlands)

    Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Trimbos, Baptist; Both, Stephanie

    2015-01-01

    d-Cycloserine (DCS) enhances extinction processes in animals. Although classical conditioning is hypothesized to play a pivotal role in the aetiology of appetitive motivation problems, no research has been conducted on the effect of DCS on the reduction of context specificity of extinction in human

  11. About one of possible cosmic causes of extinction of organisms

    International Nuclear Information System (INIS)

    Kagramanov, Yu.R.

    2004-01-01

    Based on the analysis of diverse causes of extinction of organisms in the history of the Earth and a new hypothesis of cosmic origin of oil, a suggested new possible cause of such extinction is related to intoxication with hydrocarbons arriving from the outer space

  12. Relating plant height to demographic rates and extinction vulnerability

    NARCIS (Netherlands)

    Jonge, de Melinda M.J.; Hilbers, Jelle P.; Jongejans, Eelke; Ozinga, Wim A.; Hendriks, A.J.; Huijbregts, Mark A.J.

    2018-01-01

    To prioritize conservation efforts, it is important to know which plant species are most vulnerable to extinction. Intrinsic extinction vulnerabilities depend on demographic parameters, but for many species these demographic parameters are lacking. Body size has been successfully used as proxy of

  13. Adaptive Dynamics, Control, and Extinction in Networked Populations

    Science.gov (United States)

    2015-07-09

    network geometries. From the pre-history of paths that go extinct, a density function is created from the prehistory of these paths, and a clear local...density plots of Fig. 3b. Using the IAMM to compute the most probable path and comparing it to the prehistory of extinction events on stochastic networks

  14. A comprehensive genomic history of extinct and living elephants

    DEFF Research Database (Denmark)

    Palkopoulou, Eleftheria; Lipson, Mark; Mallick, Swapan

    2018-01-01

    Elephantids are the world's most iconic megafaunal family, yet there is no comprehensive genomic assessment of their relationships. We report a total of 14 genomes, including 2 from the American mastodon, which is an extinct elephantid relative, and 12 spanning all three extant and three extinct...

  15. Late Pleistocene and Holocene mammal extinctions on continental Africa

    Science.gov (United States)

    Faith, J. Tyler

    2014-01-01

    Understanding the cause of late Quaternary mammal extinctions is the subject of intense debate spanning the fields of archeology and paleontology. In the global context, the losses on continental Africa have received little attention and are poorly understood. This study aims to inspire new discussion of African extinctions through a review of the extinct species and the chronology and possible causes of those extinctions. There are at least 24 large mammal (> 5 kg) species known to have disappeared from continental Africa during the late Pleistocene or Holocene, indicating a much greater taxonomic breadth than previously recognized. Among the better sampled taxa, these losses are restricted to the terminal Pleistocene and early Holocene, between 13,000 and 6000 yrs ago. The African extinctions preferentially affected species that are grazers or prefer grasslands. Where good terrestrial paleoenvironmental records are present, extinctions are associated with changes in the availability, productivity, or structure of grassland habitats, suggesting that environmental changes played a decisive role in the losses. In the broader evolutionary context, these extinctions represent recent examples of selective taxonomic winnowing characterized by the loss of grassland specialists and the establishment of large mammal communities composed of more ecologically flexible taxa over the last million years. There is little reason to believe that humans played an important role in African extinctions.

  16. Quark and gluon jet properties in symmetric three-jet events

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Nicod, D; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Letho, M; Newton, W M; Rankin, C; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    Quark and gluon jets with the same energy, 24GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on either a track impact parameter method or a high transverse momentum lepton tag. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity. Evidence is also presented which shows that the corresponding differences between gluon and heavy flavour jets are significantly smaller.

  17. Forward Jet Vertex Tagging: A new technique for the identification and rejection of forward pileup jets

    CERN Document Server

    The ATLAS collaboration

    2015-01-01

    The suppression of pileup forward jets is crucial for a variety of physics analyses at the LHC, ranging from VBF Higgs production to SUSY searches. A novel forward pileup tagging technique that exploits the correlation between central and forward jets originating from pileup interactions is presented. Tracking and vertex information in the central $\\eta$ region is used to indirectly tag and reject forward pileup jets that are back-to-back to central pileup jets. The pileup suppression power observed in Pythia8 simulated events increases with jet \\pt and ranges between a 30\\% and 60\\% pileup jet removal for 90\\% jet selection efficiency for jets between 20 and 50 GeV.

  18. Using neural networks with jet shapes to identify b jets in e+e- interactions

    International Nuclear Information System (INIS)

    Bellantoni, L.; Conway, J.S.; Jacobsen, J.E.; Pan, Y.B.; Wu Saulan

    1991-01-01

    A feed-forward neural network trained using backpropagation was used to discriminate between b and light quark jets in e + e - → Z 0 → qanti q events. The information presented to the network consisted of 25 jet shape variables. The network successfully identified b jets in two- and three-jet events modeled using a detector simulation. The jet identification efficiency for two-jet events was 61% and the probability to call a light quark jet a b jet equal to 20%. (orig.)

  19. Forward Jets and Forward-Central Jets at CMS

    CERN Document Server

    INSPIRE-00176215

    2012-01-01

    We report on cross section measurements for inclusive forward jet production and for the simultaneous production of a forward and a central jet in sqrt{s} = 7 TeV pp-collisions. Data collected in 2010, corresponding to an integrated luminosity of 3.14 pb^{-1}, is used for the measurements. Jets in the transverse momentum range pT = 35 - 140 GeV/c are reconstructed with the anti-kT (R = 0.5) algorithm. The extended coverage of large pseudo-rapidities is provided by the Hadronic Forward calorimeter (3.2 < \\eta < 4.7), while central jets are limited to \\eta < 2.8, covered by the main detector components. The two differential cross sections are presented as a function of the jet transverse momentum. Comparisons to next-to-leading order perturbative calculations, and predictions from event generators based on different parton showering mechanisms (PYTHIA and HERWIG) and parton dynamics (CASCADE) are shown.

  20. Theoretical investigation of the extinction coefficient of magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Fang Xiaopeng; Xuan Yimin, E-mail: ymxuan@mail.njust.edu.cn; Li Qiang [Nanjing University of Science and Technology, School of Energy and Power Engineering (China)

    2013-05-15

    A new theoretical approach for calculating the extinction coefficient of magnetic fluid is proposed, which is based on molecular dynamics (MD) simulation and T-matrix method. By means of this approach, the influence of particle diameter, particle volume fraction, and external magnetic filed on the extinction coefficient of magnetic fluid is investigated. The results show that the extinction coefficient of the magnetic fluid linearly increases with increase in the particle volume fraction. For a given particle volume fraction, the extinction coefficient increases with increase in the particle diameter which varies from 5 to 20 nm. When a uniform external magnetic filed is applied to the magnetic fluid, the extinction coefficient of the magnetic fluid presents an anisotropic feature. These results agree well with the reported experimental results. The proposed approach is applicable to investigating the optical properties of magnetic fluids.

  1. Adrenalectomy eliminates the extinction spike in autoshaping with rats.

    Science.gov (United States)

    Thomas, B L; Papini, M R

    2001-03-01

    Experiment 1, using rats, investigated the effect of adrenalectomy (ADX) on the invigoration of lever-contact performance that occurs in the autoshaping situation after a shift from acquisition to extinction (called the extinction spike). Groups of rats with ADX or sham operations were trained under spaced and massed conditions [average intertrial intervals (ITI) of either 15 or 90 s] for 10 sessions and then shifted to extinction. ADX did not affect acquisition training but it eliminated the extinction spike. Plasma corticosterone levels during acquisition were shown in Experiment 2 to be similar in rats trained under spaced or massed conditions. Adrenal participation in the emotional arousal induced by conditions of surprising nonreward (e.g., extinction) is discussed.

  2. How to detect and visualize extinction thresholds for structured PVA models

    NARCIS (Netherlands)

    Hildenbrandt, H.; Grimm, V.

    2006-01-01

    An extinction threshold is a population size below which extinction risk increases to beyond critical values. However, detecting extinction thresholds for structured population models is not straightforward because many different population structures may correspond to the same population size.

  3. Unpaired shocks during extinction weaken the contextual renewal of a conditioned discrimination

    NARCIS (Netherlands)

    Vervliet, B.; Vansteenwegen, D.; Hermans, D.

    2010-01-01

    Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this

  4. Investigations of needle-free jet injections.

    Science.gov (United States)

    Schramm-Baxter, J R; Mitragotri, S

    2004-01-01

    Jet injection is a needle-free drug delivery method in which a high-speed stream of fluid impacts the skin and delivers drugs. Although a number of jet injectors are commercially available, especially for insulin delivery, they have a low market share compared to needles possibly due to occasional pain associated with jet injection. Jets employed by the traditional jet injectors penetrate deep into the dermal and sub-dermal regions where the nerve endings are abundantly located. To eliminate the pain associated with jet injections, we propose to utilize microjets that penetrate only into the superficial region of the skin. However, the choice of appropriate jet parameters for this purpose is challenging owing to the multiplicity of factors that determine the penetration depth. Here, we describe the dependence of jet injections into human skin on the power of the jet. Dermal delivery of liquid jets was quantified using two measurements, penetration of a radiolabeled solute, mannitol, into skin and the shape of jet dispersion in the skin which was visualized using sulforhodamine B. The dependence of the amount of liquid delivered in the skin and the geometric measurements of jet dispersion on nozzle diameter and jet velocity was captured by a single parameter, jet power.

  5. Demography and the extinction of European Neanderthals

    DEFF Research Database (Denmark)

    Sørensen, Bent

    2011-01-01

    Causes previously suggested for the sudden extinction of Neanderthals (Homo neanderthalensis) in Europe, starting around 35,000 years ago, comprise food shortage, climatic effects and violence from Modern Humans. The aim here is to formulate a demographic model with reconstructed fertility and de...... uncertainty. Finally, the option of regional migration between northern, middle and southern Europe is added, in order to capture population movements away from a region in response to deteriorating or improving climate. This model accounts for population developments, including the re......-population of the Middle and Northern regions of Europe during and after the warm Eem period. However, parameter choices that give plausible results during the initial 210,000 years also predict that the Neanderthals should have survived the latter part of the Weichselian ice age, despite competing for food with Modern...

  6. Molar extinction coefficients of some fatty acids

    DEFF Research Database (Denmark)

    Sandhu, G.K.; Singh, K.; Lark, B.S.

    2002-01-01

    ) and stearic acid (C18H36O2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement......The attenuation of gamma rays in some fatty acids, viz. formic acid (CH2O2), acetic acid (C2H4O2), propionic acid (C3H6O2), butyric acid (C4H8O2), n-hexanoic acid (C6H12O2), n-caprylic acid (C8H16O2), lauric acid (C12H24O2), myristic acid (C14H28O2), palmitic acid (C16H32O2), oleic acid (C18H34O2...

  7. Promotion of cooperation by selective group extinction

    Science.gov (United States)

    Böttcher, Marvin A.; Nagler, Jan

    2016-06-01

    Multilevel selection is an important organizing principle that crucially underlies evolutionary processes from the emergence of cells to eusociality and the economics of nations. Previous studies on multilevel selection assumed that the effective higher-level selection emerges from lower-level reproduction. This leads to selection among groups, although only individuals reproduce. We introduce selective group extinction, where groups die with a probability inversely proportional to their group fitness. When accounting for this the critical benefit-to-cost ratio is substantially lowered. Because in game theory and evolutionary dynamics the degree of cooperation crucially depends on this ratio above which cooperation emerges, previous studies may have substantially underestimated the establishment and maintenance of cooperation.

  8. Is chytridiomycosis driving Darwin's frogs to extinction?

    Directory of Open Access Journals (Sweden)

    Claudio Soto-Azat

    Full Text Available Darwin's frogs (Rhinoderma darwinii and R. rufum are two species of mouth brooding frogs from Chile and Argentina that have experienced marked population declines. Rhinoderma rufum has not been found in the wild since 1980. We investigated historical and current evidence of Batrachochytrium dendrobatidis (Bd infection in Rhinoderma spp. to determine whether chytridiomycosis is implicated in the population declines of these species. Archived and live specimens of Rhinoderma spp., sympatric amphibians and amphibians at sites where Rhinoderma sp. had recently gone extinct were examined for Bd infection using quantitative real-time PCR. Six (0.9% of 662 archived anurans tested positive for Bd (4/289 R. darwinii; 1/266 R. rufum and 1/107 other anurans, all of which had been collected between 1970 and 1978. An overall Bd-infection prevalence of 12.5% was obtained from 797 swabs taken from 369 extant individuals of R. darwinii and 428 individuals representing 18 other species of anurans found at sites with current and recent presence of the two Rhinoderma species. In extant R. darwinii, Bd-infection prevalence (1.9% was significantly lower than that found in other anurans (7.3%. The prevalence of infection (30% in other amphibian species was significantly higher in sites where either Rhinoderma spp. had become extinct or was experiencing severe population declines than in sites where there had been no apparent decline (3.0%; x(2 = 106.407, P<0.001. This is the first report of widespread Bd presence in Chile and our results are consistent with Rhinoderma spp. declines being due to Bd infection, although additional field and laboratory investigations are required to investigate this further.

  9. High frequency of functional extinctions in ecological networks.

    Science.gov (United States)

    Säterberg, Torbjörn; Sellman, Stefan; Ebenman, Bo

    2013-07-25

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species. There is a growing concern that this might cause critical abundance thresholds of species to be crossed, with extinction cascades and state shifts in ecosystems as a consequence. When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems, their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species' ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence.

  10. Holographic Jet Quenching

    Science.gov (United States)

    Ficnar, Andrej

    In this dissertation we study the phenomenon of jet quenching in quark-gluon plasma using the AdS/CFT correspondence. We start with a weakly coupled, perturbative QCD approach to energy loss, and present a Monte Carlo code for computation of the DGLV radiative energy loss of quarks and gluons at an arbitrary order in opacity. We use the code to compute the radiated gluon distribution up to n=9 order in opacity, and compare it to the thin plasma (n=1) and the multiple soft scattering (n=infinity) approximations. We furthermore show that the gluon distribution at finite opacity depends in detail on the screening mass mu and the mean free path lambda. In the next part, we turn to the studies of how heavy quarks, represented as "trailing strings" in AdS/CFT, lose energy in a strongly coupled plasma. We study how the heavy quark energy loss gets modified in a "bottom-up" non-conformal holographic model, constructed to reproduce some properties of QCD at finite temperature and constrained by fitting the lattice gauge theory results. The energy loss of heavy quarks is found to be strongly sensitive to the medium properties. We use this model to compute the nuclear modification factor RAA of charm and bottom quarks in an expanding plasma with Glauber initial conditions, and comment on the range of validity of the model. The central part of this thesis is the energy loss of light quarks in a strongly coupled plasma. Using the standard model of "falling strings", we present an analytic derivation of the stopping distance of light quarks, previously available only through numerical simulations, and also apply it to the case of Gauss-Bonnet higher derivative gravity. We then present a general formula for computing the instantaneous energy loss in non-stationary string configurations. Application of this formula to the case of falling strings reveals interesting phenomenology, including a modified Bragg-like peak at late times and an approximately linear path dependence. Based

  11. Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

    Directory of Open Access Journals (Sweden)

    W. Kiessling

    2011-02-01

    Full Text Available The hypothesis that ocean acidification was a proximate trigger of the marine end-Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium-carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end-Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. doi:10.1002/mmng.201000017

  12. Accelerated modern human?induced species losses: Entering the sixth mass extinction

    OpenAIRE

    Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; Garc?a, Andr?s; Pringle, Robert M.; Palmer, Todd M.

    2015-01-01

    The oft-repeated claim that Earth?s biota is entering a sixth ?mass extinction? depends on clearly demonstrating that current extinction rates are far above the ?background? rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we...

  13. Nature and Causes of the Immediate Extinction Deficit: A Brief Review

    OpenAIRE

    Maren, Stephen

    2013-01-01

    Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression--the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effec...

  14. Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian [SLAC National Accelerator Laboratory, Stanford University,2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Wanotayaroj, Chaowaroj [Center for High Energy Physics, University of Oregon,1371 E. 13th Ave, Eugene, OR 97403 (United States)

    2015-02-12

    Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  15. Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    International Nuclear Information System (INIS)

    Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian; Wanotayaroj, Chaowaroj

    2015-01-01

    Jets with a large radius R≳1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  16. Inclusive jet spectrum for small-radius jets

    CERN Document Server

    Dasgupta, Mrinal; Salam, Gavin P.; Soyez, Gregory

    2016-01-01

    Following on our earlier work on leading-logarithmic (LLR) resummations for the properties of jets with a small radius, R, we here examine the phenomenological considerations for the inclusive jet spectrum. We discuss how to match the NLO predictions with small-R resummation. As part of the study we propose a new, physically-inspired prescription for fixed-order predictions and their uncertainties. We investigate the R-dependent part of the next-to-next-to-leading order (NNLO) corrections, which is found to be substantial, and comment on the implications for scale choices in inclusive jet calculations. We also examine hadronisation corrections, identifying potential limitations of earlier analytical work with regards to their $p_t$-dependence. Finally we assemble these different elements in order to compare matched (N)NLO+LLR predictions to data from ALICE and ATLAS, finding improved consistency for the R-dependence of the results relative to NLO predictions.

  17. Vortex breakdown in a supersonic jet

    Science.gov (United States)

    Cutler, Andrew D.; Levey, Brian S.

    1991-01-01

    This paper reports a study of a vortex breakdown in a supersonic jet. A supersonic vortical jets were created by tangential injection and acceleration through a convergent-divergent nozzle. Vortex circulation was varied, and the nature of the flow in vortical jets was investigated using several types of flow visualization, including focusing schlieren and imaging of Rayleigh scattering from a laser light sheet. Results show that the vortical jet mixed much more rapidly with the ambient air than a comparable straight jet. When overexpanded, the vortical jet exhibited considerable unsteadiness and showed signs of vortex breakdown.

  18. Supersonic induction plasma jet modeling

    International Nuclear Information System (INIS)

    Selezneva, S.E.; Boulos, M.I.

    2001-01-01

    Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders

  19. Three-dimensional simulations of cellular non-premixed jet flames

    Energy Technology Data Exchange (ETDEWEB)

    Valaer, A.L.; Frouzakis, C.E.; Boulouchos, K. [Aerothermochemistry and Combustion System Laboratory, Swiss Federal Institute of Technology, CH-8092 Zurich (Switzerland); Papas, P. [Division of Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Tomboulides, A.G. [Department of Engineering and Management of Energy Resources, University of Western Macedonia, 50100 Kozani (Greece)

    2010-04-15

    The formation, dynamics and structure of cellular flames in circular non-premixed jets are examined with three-dimensional numerical simulations incorporating detailed descriptions of chemistry and transport. Similar to past experiments reported in the literature, CO{sub 2}-diluted hydrogen in diluted or pure oxygen co-flowing streams in the proximity of the extinction limit are considered. As in the experiments, several preferred cellular states are found to co-exist with the particular state realized depending on initial conditions as well as on the jet characteristics. The simulations provide additionally the temporal transitions to different stationary or rotating cellular flames, their detailed structure, and the dependence of the scaling of the realized number of cells with the vorticity thickness. (author)

  20. Can we avoid the Sixth Mass Extinction? Setting today's extinction crisis in the context of the Big Five

    Science.gov (United States)

    Barnosky, A. D.

    2012-12-01

    While the ultimate extinction driver now—Homo sapiens—is unique with respect to the drivers of past extinctions, comparison of parallel neontological and paleontological information helps calibrate how far the so-called Sixth Mass Extinction has progressed and whether it is inevitable. Such comparisons document that rates of extinction today are approaching or exceeding those that characterized the Big Five Mass Extinctions. Continuation of present extinction rates for vertebrates, for example, would result in 75% species loss—the minimum benchmark exhibited in the Big Five extinctions—within 3 to 22 centuries, assuming constant rates of loss and no threshold effects. Preceding and during each of the Big Five, the global ecosystem experienced major changes in climate, atmospheric chemisty, and ocean chemistry—not unlike what is being observed presently. Nevertheless, only 1-2% of well-assessed modern species have been lost over the past five centuries, still far below what characterized past mass extinctions in the strict paleontological sense. For mammals, adding in the end-Pleistocene species that died out would increase the species-loss percentage by some 5%. If threatened vertebrate species were to actually go extinct, losses would rise to between 14 and 40%, depending on the group. Such observations highlight that, although many species have already had their populations drastically reduced to near-critical levels, the Sixth Mass Extinction has not yet progressed to the point where it is unavoidable. Put another way, the vast majority of species that have occupied the world in concert with Homo sapiens are still alive and are possible to save. That task, however, will require slowing the abnormally high extinction rates that are now in progress, which in turn requires unified efforts to cap human population growth, decrease the average human footprint, reduce fossil fuel use while simultaneously increasing clean energy technologies, integrate

  1. Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    Science.gov (United States)

    Nachman, Benjamin; Nef, Pascal; Schwartzman, Ariel; Swiatlowski, Maximilian; Wanotayaroj, Chaowaroj

    2015-02-01

    Jets with a large radius R ≳ 1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large- R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale r groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  2. Tying Extinction Events to Comet Impacts Large Enough to Cause an Extinction in Themselves.

    Science.gov (United States)

    Burgener, J. A.

    2017-12-01

    Comets over 35 km in size impacting Earth will create vast fireballs, and will boil large parts of the oceans, causing extinction events in themselves. They will likely provide enough energy to shatter the crust and eject large masses of molten rock from the mantle, forming traps. Traps are clearly associated with extinction events, but are not expected to cause extinctions. While Chicxulub is recognized to have occurred at the time of the K/Pg boundary layer, it is recognized as being too small in itself to cause an extinction. Are large comet impacts likely? The Kuiper belt has more than 100,000 objects over 100 km in diameter and millions over 10 km. Typically their orbits are less stable than asteroid orbits due to large bodies such as Pluto moving through the belt. The asteroid belt has only 10,000 objects over 10 km diameter. Comet impacts should be more common than asteroid impacts, yet none of the recognized craters are expected to be due to comets. There are many features on Earth that are poorly explained by Plate Tectonics that would be well explained if they were considered to be comet impact craters. A consideration of the Black Sea and the Tarim Basin will show that impact interpretations are a better fit than the present Plate Tectonics' explanations. Both basins are in the midst of mountain building from plate collisions, but are themselves not being disturbed by the plate collisions. Both are ellipses angled at 23.4 degrees to the equator, matching the angle expected for a low angle impact from a comet traveling in the ecliptic. Both are too deep at 15 km depths to be standard oceans (typically 5 km deep). Both are filled with horizontal layers of sediments, undisturbed by the mountain building occurring at the edges. Both have thin crusts and high Moho boundaries. Both have thin lithosphere. Yet both show GPS movement of the land around them moving away from them, as though they were much thicker and stronger than the surrounding land. The Tarim

  3. Size distribution of interstellar particles. III. Peculiar extinctions and normal infrared extinction

    International Nuclear Information System (INIS)

    Mathis, J.S.; Wallenhorst, S.G.

    1981-01-01

    The effect of changing the upper and lower size limits of a distribution of bare graphite and silicate particles with n(a)αa/sup -q/ is investigated. Mathis, Rumpl, and Nordsieck showed that the normal extinction is matched very well by having the small-size cutoff, a/sub -/, roughly-equal0.005 or 0.01 μm, and the large size a/sub +/, about 0.25 μm, and q = 3.5 for both substances. We consider the progressively peculiar extinctions exhibited by the well-observed stars, sigma Sco, rho Oph, and theta 1 Ori C, with values of R/sub v/[equivalentA/sub v//E(B--V)] of 3.4, 4.4, and 5.5 compared to the normal 3.1. Two (sigma Sco, rho Oph) are in a neutral dense cloud; theta 1 Ori C is in the Orion Nebula. We find that sigma Sco has a normal graphite distribution but has had its small silicate particles removed, so that a/sub -/(sil)roughly-equal0.04 μm if q = 3.5, or q(sil) = 2.6 if the size limits are fixed. However, the upper size limit on silicates remains normal. In rho Oph, the graphite is still normal, but both a/sub -/(sil) and a/sub +/(sil) are increased, to about 0.04 μm and 0.4 or 0.5 μm, respectively, if q = 3.5, or q(sil)roughly-equal1.3 if the size limits are fixed. In theta 1 Ori, the small limit on graphite has increased to about 0.04 μm, or q(gra)roughly-equal3, while the silicates are about like those in rho Oph. The calculated lambda2175 bump is broader than the observed, but normal foreground extinction probably contributes appreciably to the observed bump. The absolute amount of extinction per H atom for rho Oph is not explained. The column density of H is so large that systematic effects might be present. Very large graphite particles (a>3 μm) are required to ''hide'' the graphite without overly affecting the visual extinction, but a normal (small) graphite size distribution is required by the lambda2175 bump. We feel that it is unlikely that such a bimodal distribution exists

  4. Patient satisfaction with maxillary 3-implant overdentures using different attachment systems opposing mandibular 2-implant overdentures.

    Science.gov (United States)

    Al-Zubeidi, Mohammed I; Alsabeeha, Nabeel H M; Thomson, W Murray; Payne, Alan G T

    2012-05-01

    Patient-based outcomes with maxillary overdentures on a minimum number of implants, opposing mandibular 2-implant overdentures are not evident in the literature. To evaluate patient's satisfaction with maxillary 3-implant overdentures, opposing mandibular 2-implant overdentures, using two different attachment systems over the first 2 years of service. Forty participants wearing mandibular 2-implant overdentures for 3 years were randomly allocated to one of two similar implant system groups to receive maxillary 3-implant overdentures. Twenty participants were allocated to splinted and unsplinted attachment system treatment groups for each system. Patient satisfaction with pre-treatment complete maxillary dentures, with maxillary 3-implant overdentures at baseline and annually for 2 years, was measured using visual analogue scale questionnaires and the oral health impact profiles. Palatal coverage of the maxillary overdentures was reduced at the first annual recall. Data showed significant improvement in pain reduction, comfort, stability, and function variables of the visual analogue scale after treatment. Analysis by prosthodontic design using visual analogue scale showed no significant difference. The total oral health impact profile-14 scores after treatment for all participants, regardless of prosthodontic design, were significantly lower (more satisfied). The overall oral health impact profile-20E score at baseline was significantly higher (more satisfied) compared with pre-treatment conventional maxillary dentures. No significant changes were observed in the first or second years compared with baseline results. Twenty-two participants (84.6%) preferred reduced palatal coverage, regardless of prosthodontic design, after 1 year. Twenty participants (76.9%) still preferred reduced palatal coverage at the end of the second year. The provision of maxillary 3-implant overdentures to oppose mandibular 2-implant overdentures significantly improve levels of patient

  5. Charging process analysis of an opposed-piston two-stroke aircraft Diesel engine

    Directory of Open Access Journals (Sweden)

    Grabowski Łukasz

    2017-01-01

    Full Text Available This paper presents the research results on a 1D model of an opposed-piston two-stroke aircraft Diesel engine. The research aimed at creating a model of the engine in question to investigate how engine performance is affected by the compressor gear ratio. The power was constant at all the operating points. The research results are presented as graphs of power consumed by the compressor, compressor efficiency and brake specific fuel consumption. The optimal range of compressor gear ratio in terms of engine efficiency was defined from the research results.

  6. Heat transfer and fluid flow in regular rod arrays with opposing flow

    International Nuclear Information System (INIS)

    Yang, J.W.

    1979-01-01

    The heat transfer and fluid flow problem of opposing flow in the fully developed laminar region has been solved analytically for regular rod arrays. The problem is governed by two parameters: the pitch-to-diameter ratio and the Grashof-to-Reynolds number ratio. The critical Gr/Re ratios for flow separation caused by the upward buoyancy force on the downward flow were evaluated for a large range of P/D ratios of the triangular array. Numerical results reveal that both the heat transfer and pressure loss are reduced by the buoyancy force. Applications to nuclear reactors are discussed

  7. Sub- and supercritical jet disintegration

    Science.gov (United States)

    DeSouza, Shaun; Segal, Corin

    2017-04-01

    Shadowgraph visualization and Planar Laser Induced Fluorescence (PLIF) are applied to single orifice injection in the same facility and same fluid conditions to analyze sub- to supercritical jet disintegration and mixing. The comparison includes jet disintegration and lateral spreading angle. The results indicate that the shadowgraph data are in agreement with previous visualization studies but differ from the PLIF results that provided quantitative measurement of central jet plane density and density gradients. The study further evaluated the effect of thermodynamic conditions on droplet production and quantified droplet size and distribution. The results indicate an increase in the normalized drop diameter and a decrease in the droplet population with increasing chamber temperatures. Droplet size and distribution were found to be independent of chamber pressure.

  8. How jets get the jitters

    International Nuclear Information System (INIS)

    Zarmi, Y.

    1977-01-01

    Models in which the temporal evolution of hadronic jets and the rapidity ordering of particles within jets are correlated are discussed. Observable effects on the particle average transverse momentum (energy- and longitudinal momentum-dependence) characteristic of such models are pointed out. In particular, models in which, within jets, slow particles are produced first and fast particles come out last should exhibit the well known seagull effect, with rising, for fixed x, proportionately to the square root of the mean particle multiplicity. If, by analogy, the transverse momentum distributions of partons also exhibit such features, then we have a source of scaling violation in deep inelastic reactions that shows up at high energies rather than at low energies, and a source for an energy and Q 2 dependent in lepton pair production. (author)

  9. Electron Jet of Asymmetric Reconnection

    Science.gov (United States)

    Khotyaintsev, Yu. V.; Graham, D. B.; Norgren, C.; Eriksson, E.; Li, W.; Johlander, A.; Vaivads, A.; Andre, M.; Pritchett, P. L.; Retino, A.; hide

    2016-01-01

    We present Magnetospheric Multiscale observations of an electron-scale current sheet and electron outflow jet for asymmetric reconnection with guide field at the subsolar magnetopause. The electron jet observed within the reconnection region has an electron Mach number of 0.35 and is associated with electron agyrotropy. The jet is unstable to an electrostatic instability which generates intense waves with E(sub parallel lines) amplitudes reaching up to 300 mV/m and potentials up to 20% of the electron thermal energy. We see evidence of interaction between the waves and the electron beam, leading to quick thermalization of the beam and stabilization of the instability. The wave phase speed is comparable to the ion thermal speed, suggesting that the instability is of Buneman type, and therefore introduces electron-ion drag and leads to braking of the electron flow. Our observations demonstrate that electrostatic turbulence plays an important role in the electron-scale physics of asymmetric reconnection.

  10. Machine learning in jet physics

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    High energy collider experiments produce several petabytes of data every year. Given the magnitude and complexity of the raw data, machine learning algorithms provide the best available platform to transform and analyse these data to obtain valuable insights to understand Standard Model and Beyond Standard Model theories. These collider experiments produce both quark and gluon initiated hadronic jets as the core components. Deep learning techniques enable us to classify quark/gluon jets through image recognition and help us to differentiate signals and backgrounds in Beyond Standard Model searches at LHC. We are currently working on quark/gluon jet classification and progressing in our studies to find the bias between event generators using domain adversarial neural networks (DANN). We also plan to investigate top tagging, weak supervision on mixed samples in high energy physics, utilizing transfer learning from simulated data to real experimental data.

  11. Cutting concrete with abrasion jet

    International Nuclear Information System (INIS)

    Yie, G.G.

    1982-01-01

    Fluidyne Corporation has developed a unique process and apparatus that allow selected abrasives to be introduced into high-speed waterjet to produce abrasive-entrained waterjet that has high material-cutting capabilities, which is termed by Fluidyne as the Abrasion Jet. Such Abrasion Jet has demonstrated capability in cutting hard rock and concrete at a modest pressure of less than 1360 bars (20,000 psi) and a power input of less than 45 kW (60 horsepower). Abrasion Jet cutting of concrete is characterized by its high rate of cutting, flexible operation, good cut quality, and relatively low costs. This paper presents a general description of this technology together with discussions of recent test results and how it could be applied to nuclear decontamination and decommissioning work. 8 references

  12. QCD jets from coherent states

    Energy Technology Data Exchange (ETDEWEB)

    Curci, G [European Organization for Nuclear Research, Geneva (Switzerland); Greco, M; Srivastava, Y [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati

    1979-11-19

    A recently proposed approach to the problem of infrared and mass singularities in QCD based on the formalism of coherent states, is extended to discuss massless quark and gluon jets. The present results include all leading (ln delta) terms as well as finite terms in the energy loss epsilon, in addition to the usual ln epsilon associated with ln delta. The formulae agree with explicit perturbative calculations, whenever available. Explicit expressions for the total Ksub(T) distributions are given which take into account transverse-momentum conservation. Predictions are also made for the Q/sup 2/ dependence of the mean Ksub(T)/sup 2/ for quark and gluon jets. The jet ksub(T) distributions are extrapolated for low ksub(T) and shown to describe with good accuracy the data for eanti e..-->..qanti q..-->.. hadrons. Numerical predictions are also presented for the forthcoming PETRA, PEP and LEP machines.

  13. ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

    International Nuclear Information System (INIS)

    Bovy, Jo; Rix, Hans-Walter; Schlafly, Edward F.; Green, Gregory M.; Finkbeiner, Douglas P.

    2016-01-01

    Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps

  14. Empirical relationship of ultraviolet extinction and the interstellar diffuse bands

    International Nuclear Information System (INIS)

    Wu, C.; York, D.G.; Snow, T.P.

    1981-01-01

    New ultraviolet colors are presented for 110 hot stars. These data are combined with infrared colors and diffuse-band measurements to study the relationship of diffuse interstellar bands (lambdalambda4430, 5780, 6284) to the overall extinction curve. Equivalent widths of lambdalambda5780 and 6284 are not well correlated with infrared, visible, or ultraviolet extinction measurements for stars in our sample. The central depth of lambda4430 is well correlated with visible and infrared extinction, but less well correlated with UV extinction at 1800 A. lambda4430 is strongly correlated with the strength of the 2200-A bump. Our data suggest that if small grains account for the general rise in UV extinction, the diffuse bands are not formed in these grains. lambda4430 may well arise in large grains and/or in the material responsible for the 2200-A bump. Correlations with UV extinctions derived by other authors are discussed in detail. It is suggested that definitions of extinction parameters and band shapes, as well as selection effects in small samples of stars, may still compromise conclusions based on correlation studies such as we are attempting

  15. LINE DERIVED INFRARED EXTINCTION TOWARD THE GALACTIC CENTER

    International Nuclear Information System (INIS)

    Fritz, T. K.; Gillessen, S.; Dodds-Eden, K.; Lutz, D.; Genzel, R.; Raab, W.; Ott, T.; Pfuhl, O.; Eisenhauer, F.; Yusef-Zadeh, F.

    2011-01-01

    We derive the extinction curve toward the Galactic center (GC) from 1 to 19 μm. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction-free flux reference is the 2 cm continuum emission observed by the Very Large Array. Toward the inner 14'' x 20'', we find an extinction of A 2.166μm = 2.62 ± 0.11, with a power-law slope of α = -2.11 ± 0.06 shortward of 2.8 μm, consistent with the average near-infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 μm. We find that it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance-dependent extinction with our distance-independent extinction, we derive the distance to the GC to be R 0 = 7.94 ± 0.65 kpc. Toward Sgr A* (r H = 4.21 ± 0.10, A Ks = 2.42 ± 0.10, and A L' = 1.09 ± 0.13.

  16. ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

    Energy Technology Data Exchange (ETDEWEB)

    Bovy, Jo [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H4 (Canada); Rix, Hans-Walter; Schlafly, Edward F. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Green, Gregory M.; Finkbeiner, Douglas P., E-mail: bovy@astro.utoronto.ca [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-02-20

    Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps.

  17. MODELING GALACTIC EXTINCTION WITH DUST AND 'REAL' POLYCYCLIC AROMATIC HYDROCARBONS

    International Nuclear Information System (INIS)

    Mulas, Giacomo; Casu, Silvia; Cecchi-Pestellini, Cesare; Zonca, Alberto

    2013-01-01

    We investigate the remarkable apparent variety of galactic extinction curves by modeling extinction profiles with core-mantle grains and a collection of single polycyclic aromatic hydrocarbons. Our aim is to translate a synthetic description of dust into physically well-grounded building blocks through the analysis of a statistically relevant sample of different extinction curves. All different flavors of observed extinction curves, ranging from the average galactic extinction curve to virtually 'bumpless' profiles, can be described by the present model. We prove that a mixture of a relatively small number (54 species in 4 charge states each) of polycyclic aromatic hydrocarbons can reproduce the features of the extinction curve in the ultraviolet, dismissing an old objection to the contribution of polycyclic aromatic hydrocarbons to the interstellar extinction curve. Despite the large number of free parameters (at most the 54 × 4 column densities of each species in each ionization state included in the molecular ensemble plus the 9 parameters defining the physical properties of classical particles), we can strongly constrain some physically relevant properties such as the total number of C atoms in all species and the mean charge of the mixture. Such properties are found to be largely independent of the adopted dust model whose variation provides effects that are orthogonal to those brought about by the molecular component. Finally, the fitting procedure, together with some physical sense, suggests (but does not require) the presence of an additional component of chemically different very small carbonaceous grains.

  18. Sexual selection affects local extinction and turnover in bird communities

    Science.gov (United States)

    Doherty, P.F.; Sorci, G.; Royle, J. Andrew; Hines, J.E.; Nichols, J.D.; Boulinier, T.

    2003-01-01

    Predicting extinction risks has become a central goal for conservation and evolutionary biologists interested in population and community dynamics. Several factors have been put forward to explain risks of extinction, including ecological and life history characteristics of individuals. For instance, factors that affect the balance between natality and mortality can have profound effects on population persistence. Sexual selection has been identified as one such factor. Populations under strong sexual selection experience a number of costs ranging from increased predation and parasitism to enhanced sensitivity to environmental and demographic stochasticity. These findings have led to the prediction that local extinction rates should be higher for species/populations with intense sexual selection. We tested this prediction by analyzing the dynamics of natural bird communities at a continental scale over a period of 21 years (1975-1996), using relevant statistical tools. In agreement with the theoretical prediction, we found that sexual selection increased risks of local extinction (dichromatic birds had on average a 23% higher local extinction rate than monochromatic species). However, despite higher local extinction probabilities, the number of dichromatic species did not decrease over the period considered in this study. This pattern was caused by higher local turnover rates of dichromatic species, resulting in relatively stable communities for both groups of species. Our results suggest that these communities function as metacommunities, with frequent local extinctions followed by colonization. Anthropogenic factors impeding dispersal might therefore have a significant impact on the global persistence of sexually selected species.

  19. Advanced thermally stable jet fuels

    Energy Technology Data Exchange (ETDEWEB)

    Schobert, H.H.

    1999-01-31

    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume

  20. Properties of Supersonic Impinging Jets

    Science.gov (United States)

    Alvi, F. S.; Iyer, K. G.; Ladd, J.

    1999-11-01

    A detailed study examining the behavior of axisymmetric supersonic jets impinging on a ground plane is described. Our objective is to better understand the aeroacoustics governing this complex flowfield which commonly occurs in the vicinity of STOVL aircraft. Flow issuing through a Mach 1.5 C-D and a converging sonic nozzle is examined over a wide parametric range. For some cases a large diameter circular 'lift' plate, with an annular hole through which the jet is issued, is attached at the nozzle exit to simulate a generic airframe. The impinging jet flowfield was examined using Particle Image Velocimetry (PIV), which provides the velocity field for the entire region and shadowgraph visualization techniques. Near-field acoustic, as well as, mean and unsteady pressure measurements on the ground and lift plate surfaces were also obtained. The velocity field data, together with the surface flow measurements have resulted in a much better understanding of this flow from a fundamental standpoint while also identifying critical regions of interest for practical applications. Some of these findings include the presence of a stagnation bubble with recirculating flow; a very high speed (transonic/supersonic) radial wall jet; presence of large, spatially coherent turbulent structures in the primary jet and wall jet and high unsteady loads on the ground plane and lift plates. The results of a companion CFD investigation and its comparison to the experimental data will also be presented. Very good agreement has been found between the computational and experimental results thus providing confidence in the development of computational tools for the study of such flows.