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Sample records for quasi-elastic barrier distribution

  1. Important influence of single neutron stripping coupling on near-barrier 8Li + 90Zr quasi-elastic scattering

    Science.gov (United States)

    Pakou, A.; Keeley, N.; Pierroutsakou, D.; Mazzocco, M.; Acosta, L.; Aslanoglou, X.; Boiano, A.; Boiano, C.; Carbone, D.; Cavallaro, M.; Grebosz, J.; La Commara, M.; Manea, C.; Marquinez-Duran, G.; Martel, I.; Parascandolo, C.; Rusek, K.; Sánchez-Benítez, A. M.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Strano, E.; Torresi, D.; Trzcińska, A.; Watanabe, Y. X.; Yamaguchi, H.

    2015-07-01

    Quasi-elastic scattering data were obtained for the radioactive nucleus 8Li on a 90Zr target at the near-barrier energy of 18.5MeV over the angular range to 80°. They were analyzed within the coupled channels and coupled reaction channels frameworks pointing to a strong coupling effect for single neutron stripping, in contrast to 6, 7 Li + 90 Zr elastic scattering at similar energies, a non-trivial result linked to detailed differences in the structure of these Li isotopes.

  2. Mapping from quasi-elastic scattering to fusion reactions

    CERN Document Server

    Hagino, K

    2014-01-01

    The fusion barrier distribution has provided a nice representation for the channel coupling effects on heavy-ion fusion reactions at energies around the Coulomb barrier. Here we discuss how one can extract the same representation using the so called sum-of-differences (SOD) method with quasi-elastic scattering cross sections. In contrast to the conventional quasi-elastic barrier distribution, the SOD barrier distribution has an advantage in that it can be applied both to non-symmetric and symmetric systems. It is also the case that the correspondence to the fusion barrier distribution is much better than the quasi-elastic barrier distribution. We demonstrate its usefulness by studying $^{16}$O+$^{144}$Sm, $^{58}$Ni+$^{58}$Ni, and $^{12}$C+$^{12}$C systems.

  3. Important influence of single neutron stripping coupling on near-barrier {sup 8}Li + {sup 90}Zr quasi-elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pakou, A.; Aslanoglou, X.; Sgouros, O.; Soukeras, V. [The University of Ioannina, Department of Physics and HINP, Ioannina (Greece); Keeley, N. [National Centre for Nuclear Research, Otwock (Poland); Pierroutsakou, D.; Boiano, A.; Parascandolo, C. [INFN, Napoli (Italy); Mazzocco, M.; Soramel, F.; Strano, E.; Torresi, D. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); INFN, Padova (Italy); Acosta, L. [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico (Mexico); INFN, Catania (Italy); Boiano, C. [INFN, Milano (Italy); Carbone, D.; Cavallaro, M. [INFN Laboratori Nazionali del Sud, Catania (Italy); Grebosz, J. [The Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN), Krakow (Poland); La Commara, M. [INFN, Napoli (Italy); Universita di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); Manea, C. [INFN, Padova (Italy); Marquinez-Duran, G.; Martel, I. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Rusek, K.; Trzcinska, A. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Sanchez-Benitez, A.M. [Centro de Fisica Nuclear da Universidade de Lisboa, Lisboa (Portugal); Signorini, C. [LNL, INFN, Legnaro (Italy); Stiliaris, E. [University of Athens, Institute of Accelerating Systems and Applications and Department of Physics, Athens (Greece); Watanabe, Y.X. [High Energy Accelerator Research Organization (KEK), Institute of Particle and Nuclear Studies (IPNS), Ibaraki (Japan); Yamaguchi, H. [University of Tokyo, RIKEN campus, Center for Nuclear Study (CNS), Saitama (Japan)

    2015-07-15

    Quasi-elastic scattering data were obtained for the radioactive nucleus {sup 8}Li on a {sup 90}Zr target at the near-barrier energy of 18.5 MeV over the angular range θ{sub lab} = 15 {sup circle} to 80 . They were analyzed within the coupled channels and coupled reaction channels frameworks pointing to a strong coupling effect for single neutron stripping, in contrast to {sup 6,} {sup 7}Li + {sup 90}Zr elastic scattering at similar energies, a non-trivial result linked to detailed differences in the structure of these Li isotopes. (orig.)

  4. Breakup Effect of Weakly Bound Projectile on the Barrier Distribution Around Coulomb Barrier

    Institute of Scientific and Technical Information of China (English)

    贾会明; 林承键; 张焕乔; 刘祖华; 喻宁; 杨峰; 徐新星; 贾飞; 吴振东; 张世涛

    2012-01-01

    The excitation function of quasi-elastic (QEL) scattering at a backward angle has been measured for 9^Be+208^Pb. The barrier distribution was extracted by means of the first derivative of the measured excitation function and calculated with the coupled-channel model. The present work shows that the experimental barrier distribution extracted from QEL scattering is shifted to the low energy side by 1.5 MeV as compared with the theoretical one. This energy discrepancy indicates that breakup is important in the colliding processes of the weakly bound nucleus system.

  5. Studying neutrino oscillations using quasi-elastic events in MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Kumaratunga, Sujeewa Terasita [Univ. of Minnesota, Minneapolis, MN (United States)

    2008-02-01

    MINOS (Main Injector Neutrino Oscillation Search), is a long baseline neutrino experiment designed to search for neutrino oscillations using two detectors at Fermi National Accelerator Laboratory, IL (Near Detector) and Soudan, MN (Far Detector). It will study vμ → vτ oscillations and make a measurement on the oscillation parameters, Δm$2\\atop{23}$ and sin223, via a vμ beam made at Fermilab. Charge current neutrino interactions in the MINOS detectors are of three types: quasi-elastic scattering (QEL), resonance scattering (RES) and deep inelastic scattering (DIS). Of these, quasi-elastic scattering leaves the cleanest signal with just one μ and one proton in the final state, thus rendering the reconstruction of the neutrino energy more accurate. This thesis will outline a method to separate QEL events from the others in the two detectors and perform a calculation of Δm$2\\atop{23}$ and sin223 using those events. The period under consideration was May 2005 to February 2006. The number of observed quasi-elastic events with energies below 10 GeV was 29, where the expected number was 60 ± 3. A fit to the energy distribution of these events gives Δm$2\\atop{23}$ = 2.91$+0.49\\atop{-0.53}$(stat)$+0.08\\atop{-0.09}$(sys) x 10-3 eV2 and sin223 = 0.990-0.180(stat)-0.030(sys).

  6. Quasi-elastic neutron scattering studies of protein dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rorschach, H.E.

    1993-05-25

    Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.

  7. Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions

    CERN Document Server

    Gran, R; Bóna, M; Boutigny, D; Couderc, F; Karyotakis, Yu; Lees, J P; Poireau, V; Tisserand, V; Zghiche, A; Graugès-Pous, E; Palano, A; Pappagallo, M; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Wenzel, W A; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schröder, T; Steinke, M; Boyd, J T; Burke, J P; Cottingham, W N; Walker, D; Çuhadar-Dönszelmann, T; Fulsom, B G; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Khan, A; Kyberd, P; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, Yu K; Best, D S; Bondioli, M; Bruinsma, M; Chao, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M A; Mommsen, R K; Röthel, W; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Long, O; Shen, B C; Wang, K; Zhang, L; Hadavand, H K; Hill, E J; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Andreassen, R; Mancinelli, G; Meadows, B T; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nauenberg, U; Olivas, A; Ruddick, W O; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Chen, A; Eckhart, E A; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Spaan, B; Brandt, T; Klose, V; Lacker, H M; Mader, W F; Nogowski, R; Petzold, A; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Grenier, P; Latour, E; Thiebaux, C; Verderi, M; Bard, D J; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Flack, R L; Gaillard, J R; Nash, J A; Nikolich, M B; Panduro-Vazquez, W; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Fritsch, M; Schott, G; Arnaud, N; Davier, M; Grosdidier, G; Höcker, A; Le Diberder, F R; Lepeltier, V; Lutz, A M; Oyanguren, A; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Stocchi, A; Wang, W F; Wormser, G; Cheng, C H; Lange, D J; Wright, D M; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; George, K A; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; Di Lodovico, F; Menges, W; Sacco, R; Brown, C L; Cowan, G; Flächer, H U; Hopkins, D A; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Kelly, M P; Lafferty, G D; Naisbit, M T; Williams, J C; Yi, J I; Chen, C; Hulsbergen, W D; Jawahery, A; Lae, C K; Roberts, D A; Simi, G; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Saremi, S; Stängle, H; Willocq, S Y; Cowan, R; Koeneke, K; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Kim, H; Patel, P M; Potter, C T; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; Cavallo, N; De Nardo, Gallieno; Del Re, D; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Piccolo, D; Sciacca, C; Baak, M; Bulten, H; Raven, G; Snoek, H L; Jessop, C P; LoSecco, J M; Allmendinger, T; Benelli, G; Gan, K K; Honscheid, K; Hufnagel, D; Jackson, P D; Kagan, H; Kass, R; Pulliam, T; Rahimi, A M; Ter-Antonian, R; Wong, Q K; Blount, N L; Brau, J E; Frey, R; Igonkina, O; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Galeazzi, F; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Chauveau, J; David, P; Del Buono, L; La Vaissière, C de; Hamon, O; Hartfiel, B L; John, M J J; Leruste, P; Malcles, J; Ocariz, J; Roos, L; Therin, G; Behera, P K; Gladney, L; Panetta, J; Biasini, M; Covarelli, R; Pioppi, M; Angelini, C; Batignani, G; Bettarini, S; Bucci, F; Calderini, G; Carpinelli, M; Cenci, R; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J; Haire, M; Judd, D; Wagoner, D E; Biesiada, J; Danielson, N; Elmer, P; Lau, Y P; Lü, C; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; D'Orazio, A; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Safai-Tehrani, F; Voena, C; Ebert, M; Schröder, H; Waldi, R; Adye, T; De Groot, N; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, Witold; Legendre, M; Mayer, B; Vasseur, G; Yéche, C; Zito, M; Park, W; Purohit, M V; Weidemann, A W; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Boyarski, A M; Claus, R; Coleman, J P; Convery, M R; Cristinziani, M; Dingfelder, J C; Dong, D; Dorfan, J; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W M; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Halyo, V; Hast, C; Hrynóva, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Libby, J; Luitz, S; Lüth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Messner, R; Müller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Vavra, J; Van Bakel, N; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Roat, C; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Satpathy, A; Schilling, C J; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Vitale, L; Azzolini, V; Martínez-Vidal, F; Banerjee, Sw; Bhuyan, B; Brown, C M; Fortin, D; Hamano, K; Kowalewski, R V; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Band, H R; Chen, X; Cheng, B; Dasu, S; Datta, M; Eichenbaum, A M; Flood, K T; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Mellado, B; Mihályi, A; Mohapatra, A K; Pan, Y; Pierini, M; Prepost, R; Tan, P; Wu, S L; Yu, Z; Neal, H; Back, B B

    2006-01-01

    The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of which half are charged-current quasi-elastic interactions nu-mu n to mu- p occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for oxygen and assume the form factor is approximately a dipole with one parameter, the axial vector mass M_A, and fit to the shape of the distribution of the square of the momentum transfer from the nucleon to the nucleus. Our best fit result for M_A = 1.20 \\pm 0.12 GeV. Furthermore, this analysis includes updated vector form factors from recent electron scattering experiments and a discussion of the effects of the nucleon momentum on the shape of the fitted distributions.

  8. Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer

    Science.gov (United States)

    Mardor, Y.; Aclander, J.; Alster, J.; Barton, D.; Bunce, G.; Carroll, A.; Christensen, N.; Courant, H.; Durrant, S.; Gushue, S.; Heppelmann, S.; Kosonovsky, E.; Mardor, I.; Marshak, M.; Makdisi, Y.; Minor, E. D.; Navon, I.; Nicholson, H.; Piasetzky, E.; Roser, T.; Russell, J.; Sutton, C. S.; Tanaka, M.; White, C.; Wu, J.-Y.

    1998-10-01

    We measured the high-momentum transfer [Q2=4.8 and 6.2 (GeV/c)2] quasi-elastic 12C(p,2p) reaction at θcm~=90 deg for 6 and 7.5 GeV/c incident protons. The momentum components of both outgoing protons and the missing energy and momentum of the proton in the nucleus were measured. We verified the validity of the quasi-elastic picture for ground state momenta up to about 0.5 GeV/c. Transverse and longitudinal momentum distributions of the target proton were measured. They have the same shape with a large momentum tail which is not consistent with independent particle models. We observed that the transverse distribution gets wider as the longitudinal component increases in the beam direction.

  9. Cross section measurements for quasi-elastic neutrino-nucleus scattering with the MINOS near detector

    Energy Technology Data Exchange (ETDEWEB)

    Dorman, Mark Edward [Univ. College London, Bloomsbury (United Kingdom)

    2008-04-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory (FNAL) in Chicago, Illinois. MINOS measures neutrino interactions in two large iron-scintillator tracking/sampling calorimeters; the Near Detector on-site at FNAL and the Far Detector located in the Soudan mine in northern Minnesota. The Near Detector has recorded a large number of neutrino interactions and this high statistics dataset can be used to make precision measurements of neutrino interaction cross sections. The cross section for charged-current quasi-elastic scattering has been measured by a number of previous experiments and these measurements disagree by up to 30%. A method to select a quasi-elastic enriched sample of neutrino interactions in the MINOS Near Detector is presented and a procedure to fit the kinematic distributions of this sample and extract the quasi-elastic cross section is introduced. The accuracy and robustness of the fitting procedure is studied using mock data and finally results from fits to the MINOS Near Detector data are presented.

  10. Quasi-elastic nuclear scattering at high energies

    Science.gov (United States)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.

    1992-01-01

    The quasi-elastic scattering of two nuclei is considered in the high-energy optical model. Energy loss and momentum transfer spectra for projectile ions are evaluated in terms of an inelastic multiple-scattering series corresponding to multiple knockout of target nucleons. The leading-order correction to the coherent projectile approximation is evaluated. Calculations are compared with experiments.

  11. Quasi-Elastic Scattering in MINERvA

    CERN Document Server

    McFarland, Kevin S

    2011-01-01

    Determination of the quasi-elastic scattering cross-section over a broad range of neutrino energies, nuclear targets and Q^2 is a primary goal of the MINERvA experiment. We present preliminary comparisons of data and simulation in a sample rich in anti-{\

  12. Quasi-elastic Charm Production In Neutrino-nucleon Scattering

    CERN Document Server

    Bischofberger, M

    2005-01-01

    A study of quasi elastic charm production in charged current neutrino-nucleon scattering is presented. A sample of about 1.3 million interactions recorded with the NOMAD detector in the CERN SPS wide band neutrino beam has been searched for quasi elastically produced charmed baryons ( L+c,Sc and S*c ). The search has been performed in two exclusive decay channels of the L+c, both including a L . Also, the semi-inclusive decay channels L+c,Sc,S *c→L+X have been studied. Kinematic selection criteria have been chosen in order to obtain samples enriched with quasi elastic charm events. Signal efficiencies and background expectations have been estimated by Monte Carlo simulations. The observed number of events in each searched channel has been found to agree with the background expectation from charged and neutral current reactions and an upper limit for the cross section has been derived. For the quasi elastic charm production cross section averaged over the neutrino energy spectrum (&lan...

  13. Surface Diffuseness Anomaly in 16O+208pb Quasi-elastic Scattering at Backward Angle

    Institute of Scientific and Technical Information of China (English)

    JIA Hui-Ming; XU Xin-Xing; BAI Chun-Lin; YU Ning; LIN Cheng-Jian; ZHANG Huan-Qiao; LIU Zu-Hua; YANG Feng; JIA Fei; ZHANG Chun-Lei; AN Guang-Peng; WU Zhen-Dong

    2008-01-01

    @@ The quasi-elastic scattering excitation function of the doubly magic 16O+208pb system at a backward angle is measured at sub-barrier energies with high precision. The diffuseness parameters extracted from both the single-channel and the coupled-channels calculations give almost the same value α = 0.76±0.04 fm. The results show that the coupling effect is negligible for the spherical system. The obtained value is smaller than the extracted value from the fusion excitation function, but larger than the value of α = 0.63 fm, which is from the systematic analysis of elastic scattering data.

  14. Quasi-Elastic Scattering of 16C from 12C at 47.5 MeV/Nucleon

    Institute of Scientific and Technical Information of China (English)

    FAN Feng-Ying; ZHENG Tao; YE Yan-Lin; JIANG Dong-Xing; HUA Hui; LI Zhi-Huan; GE Yu-Cheng; LI Xiang-Qing; LOU Jian-Ling; SHI Fan; LV Lin-Hui; CAO Zhong-Xin; NIE Peng-Xuan; LI Qi-Te; SONG Yu-Shou; LU Fei; XU Hu-Shan; HU Zheng-Guo; WANG Meng; ZHANG Xue-Ying; LI Chen; CHEN Ruo-Fu; TANG Bin; XU Zhi-Guo; YUE Ke; ZHANG Ya-Peng; ZANG Yong-Dong; ZHANG Xue-Heng; YAO Xiang-Wu; CHEN Jin-Da; TU Xiao-Lin; ZHANG Jie; WU Da-Peng; BAI Zhen

    2009-01-01

    Differential cross sections for the quasi-elastic scattering of 16C at 47.5 MeV/nucleon from 12C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.

  15. Hard diffraction from quasi-elastic dipole scattering

    CERN Document Server

    Bialas, A

    1996-01-01

    The contribution to diffraction dissociation of virtual photons due to quasi-elastic scattering of the q-\\bar q component is calculated in the framework of the QCD dipole picture. Both longitudinal and transverse components of the cross-section are given. It is shown that, at fixed mass of the diffractively produced system, quantum mechanical interference plays an important r\\^ ole. Phenomenological consequences are discussed.

  16. Recent Measurements of Neutrino-Nucleus Quasi-Elastic Scattering

    CERN Document Server

    Wascko, M O

    2011-01-01

    We present recent measurements of neutrino charged current quasi-elastic (CC QE) scattering, nu_mu + p -> mu- + n. Measurements of CC QE on carbon near 1 GeV by MiniBooNE and SciBooNE, as well as measurements on iron at 3 GeV by MINOS, disagree with current interaction models, while measurements at higher energies on carbon by NOMAD show excellent agreement with those same models.

  17. Spectrum of recoil nucleons in quasi-elastic neutrino-nucleus interactions

    Energy Technology Data Exchange (ETDEWEB)

    Juszczak, C.; Nowak, J.A.; Sobczyk, J.T. [Wroclaw University, Institute of Theoretical Physics, Wroclaw (Poland)

    2005-02-01

    We have analyzed the consequences of introducing the local density approximation combined with an effective nuclear momentum-dependent potential into the CC quasi-elastic neutrino-nucleus scattering. We note that the distribution of recoil nucleons momenta becomes smooth for low momentum values and the sharp threshold is removed. Our results may be relevant for Sci-Fi detector analysis of K2K experiments. The total amount of observed recoil protons is reduced because some of them remain bound inside the nucleus. We compare theoretical predictions for a probability of such events with the results given by NUX+FLUKA MC simulations. (orig.)

  18. Effect of coupling in the 28Si+154Sm reaction studied by quasi-elastic scattering

    Science.gov (United States)

    Kaur, Gurpreet; Behera, B. R.; Jhingan, A.; Nayak, B. K.; Dubey, R.; Sharma, Priya; Thakur, Meenu; Mahajan, Ruchi; Saneesh, N.; Banerjee, Tathagata; Khushboo, Kumar, A.; Mandal, S.; Saxena, A.; Sugathan, P.; Rowley, N.

    2016-09-01

    The study of the coupling to collective states of the 28Si projectile and 154Sm target in fusion mechanism is reported. Understanding such couplings is important as they influence the barrier height and the formation probability of the compound nuclei, which in turn may be related to the synthesis of superheavy elements in heavier systems. In the present work, before performing the coupled-channel calculations, we wish to obtain an experimental signature of coupling to projectile and target excitation through barrier distribution (BD) study. To this end, the BDs of the 28Si+154Sm and 16O+154Sm systems have been compared using existing fusion data, scaled to compensate for the differences between the nominal Coulomb barriers and the respective coupling strengths. However, the large error bars on the high-energy side of the fusion BD prevent any definite identification of such signatures. We have, therefore, performed a quasi-elastic (QE) scattering experiment for the heavier 28Si+154Sm system and compared its results with existing QE data for the 16O projectile. Since QE BDs are precise at higher energies, the comparison has shown that the BD of 28Si+154Sm is similar to that of 16O+154Sm to a large extent except for a peaklike structure on the higher energy side. The similarity shows that the 154Sm deformation plays a major role in the fusion mechanism of 28Si+154Sm system. The peaklike structure is attributed to 28Si excitation. In contrast with previous studies, it is found that a coupled-channel calculation with vibrational coupling to the first 2+ state of 28Si reproduces this structure rather well. However, an almost identical result is found with the rotational coupling scheme if one considers the large positive hexadecapole deformation of the projectile. A value around that given by Möller and Nix (β4≈0.25 ) leads to a strong cancellation in the re-orientation term that couples the 2+ state back to itself, making that state look vibrational in this

  19. Measurement of Muon Neutrino Quasi-Elastic Scattering on Carbon

    CERN Document Server

    Aguilar-Arevalo, A A; Brice, S J; Brown, B C; Bugel, L; Cao, J; Coney, L; Conrad, J M; Cox, D C; Curioni, A; Djurcic, Z; Finley, D A; Fleming, B T; Ford, R; García, F G; Garvey, G T; Green, C; Green, J A; Hart, T L; Hawker, E; Imlay, R; Johnson, R A; Kasper, P; Katori, T; Kobilarcik, T; Kourbanis, I; Koutsoliotas, S; Laird, E M; Link, J M; Liu, Y; Liu, Y; Louis, W C; Mahn, K B M; Marsh, W; Martin, P S; McGregor, G; Metcalf, W; Meyers, P D; Mills, F; Mills, G B; Monroe, J; Moore, C D; Nelson, R H; Nienaber, P; Ouedraogo, S; Patterson, R B; Perevalov, D; Polly, C C; Prebys, E; Raaf, Jennifer L; Ray, H; Roe, B P; Russell, A D; Sandberg, V; Schirato, R; Schmitz, D; Shaevitz, M H; Shoemaker, F C; Smith, D; Sorel, M; Spentzouris, P; Stancu, I; Stefanski, R J; Sung, M; Tanaka, H A; Tayloe, R; Tzanov, M; Vande Water, R; Wascko, M O; White, D H; Wilking, M J; Yang, H J; Zeller, G P; Zimmerman, E D

    2007-01-01

    Low energy (200quasi-elastic (CCQE) neutrino interactions to predict signal samples. Using a high-statistics sample of muon neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events observed in a carbon-based detector. The extracted parameters include an effective axial mass, M_A = 1.23 +/- 0.20 GeV, used to describe the four-momentum dependence of the axial-vector form factor of the nucleon and a Pauli-suppression parameter, kappa = 1.019 +/- 0.011.

  20. Neutron Angular Scatter Effects in 3DHZETRN: Quasi-Elastic

    Science.gov (United States)

    Wilson, John W.; Werneth, Charles M.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2017-01-01

    The current 3DHZETRN code has a detailed three dimensional (3D) treatment of neutron transport based on a forward/isotropic assumption and has been compared to Monte Carlo (MC) simulation codes in various geometries. In most cases, it has been found that 3DHZETRN agrees with the MC codes to the extent they agree with each other. However, a recent study of neutron leakage from finite geometries revealed that further improvements to the 3DHZETRN formalism are needed. In the present report, angular scattering corrections to the neutron fluence are provided in an attempt to improve fluence estimates from a uniform sphere. It is found that further developments in the nuclear production models are required to fully evaluate the impact of transport model updates. A model for the quasi-elastic neutron production spectra is therefore developed and implemented into 3DHZETRN.

  1. Quasi-elastic scattering of a secondary sup 6 He beam on a sup 9 Be target at 25 MeV/nucleon

    CERN Document Server

    Chen Tao; Li Zhi Huan; Jiang Dong Xing; Hua Hui; Li Xiang Qing; Wang Quan Jin; Ge Yuch Eng; Pang Dan Yang; Di Zhenyu; Jin Ge; Xiao Guo Qing; Guo Zhong Yan; Xiao Zhi Gang; Wang Hong Wei; Zhang Bao Guo; Wu He Yu; Li Jia Xing; Sun Zhi Yu; Zhan Wen Long

    2002-01-01

    The quasi-elastic scattering of a secondary sup 6 He beam (25 MeV/n) on a sup 9 Be target has been measured for the first time with the application of a sophisticated tracking detector system. The angular distribution is reported. A phenomenological optical potential is obtained by fitting the experimental data, which encourages more accurate experimental measurements

  2. Quasi-elastic Scattering of a Secondary 6He Beam on a 9Be Target at 25MeV/Nucleon

    Institute of Scientific and Technical Information of China (English)

    陈陶; 叶沿林; 李智焕; 江栋兴; 华辉; 李湘庆; 王全进; 葛榆成; 庞丹阳; 狄振宇; 靳根明; 肖国青; 郭忠言; 肖志刚; 王宏伟; 张保国; 吴和宇; 李家兴; 孙志宇; 詹文龙

    2002-01-01

    The quasi-elastic scattering of a secondary 6He beam (25 MeV/n) on a 9Be target has been measured for the firsttime with the application of a sophisticated tracking detector system. The angular distribution is reported. Aphenomenological optical potential is obtained by fitting the experimental data, which encourages more accurateexperimental measurements.

  3. Anharmonic behavior in the multisubunit protein apoferritin as revealed by quasi-elastic neutron scattering.

    Science.gov (United States)

    Telling, Mark T F; Neylon, Cameron; Kilcoyne, Susan H; Arrighi, Valeria

    2008-09-04

    Quasi-elastic neutron scattering (QENS) has been used to study the deviation from Debye-law harmonic behavior in lyophilized and hydrated apoferritin, a naturally occurring, multisubunit protein. Whereas analysis of the measured mean squared displacement (msd) parameter reveals a hydration-dependent inflection above 240 K, characteristic of diffusive motion, a hydration-independent inflection is observed at 100 K. The mechanism responsible for this low-temperature anharmonic response is further investigated, via analysis of the elastic incoherent neutron scattering intensity, by applying models developed to describe side-group motion in glassy polymers. Our results suggest that the deviation from harmonic behavior is due to the onset of methyl group rotations which exhibit a broad distribution of activated processes ( E a,ave = 12.2 kJ.mol (-1), sigma = 5.0 kJ x mol (-1)). Our results are likened to those reported for other proteins.

  4. Quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei

    CERN Document Server

    Kovalchuk, V I

    2016-01-01

    The observed cross sections of quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei are described within the framework of the diffraction nuclear model and the model of nucleus-nucleus scattering in the high-energy approximation with a double folding potential, for intermediate energies of the incident particles. The calculations make use of realistic distributions of nucleon densities and take account of the Coulomb interaction and inelastic scattering with excitation of low-lying collective states of the target.

  5. Neutrino-nucleus quasi-elastic and 2p2h interactions up to 10 GeV

    CERN Document Server

    Gran, R; Sanchez, F; Vacas, M J Vicente

    2013-01-01

    We extend to 10 GeV results from a microscopic calculation of charged-current neutrino-nucleus reactions that do not produce a pion in the final state. For the class of events coming from neutrino interactions with two nucleons producing two holes (2p2h), limiting the calculation to three-momentum transfers less than 1.2 GeV produces a two dimensional distribution in momentum and energy transfer that is roughly constant as a function of energy. The cross section for 2p2h interactions scales with the number of nucleons for isoscalar nuclei, similar to the quasi-elastic (QE) cross section. When limited to momentum transfers below 1.2 GeV, the cross section is 26% of the QE cross section at 3 GeV, but 14% if we neglect a Delta1232 resonance absorption component. The same quantities are 33% and 17% for anti-neutrinos. For the quasi-elastic interactions, the full nuclear model with long range correlations produces an even larger, but approximately constant distortion of the shape of the four-momentum transfer at a...

  6. Study of the Quasi-Elastic Scattering in the NOvA Detector Prototype

    Energy Technology Data Exchange (ETDEWEB)

    Betancourt, Minerba [Univ. of Minnesota, Minneapolis, MN (United States)

    2013-06-01

    NOvA is a 810 km long base-line neutrino oscillation experiment with two detectors (far 14 KTon and near detector 300 Ton) currently being installed in the NUMI o -axis neutrino beam produced at Fermilab. A 222 Ton prototype NOvA detector (NDOS) was built and operated in the neutrino beam for over a year to understand the response of the detector and its construction. The goal of this thesis is to study the muon neutrino interaction data collected in this test, specifically the identification of quasi-elastic charged-current interactions and measure the behavior of the quasi-elastic muon neutrino cross section.

  7. Precursor of pion condensation: The softening of the quasi-elastic peak

    Science.gov (United States)

    Alberico, W. M.; Ericson, M.; Molinari, A.

    1980-05-01

    The phase transition of pion condensation is heralded in the disordered phase by an increase in the life time of the fluctuations for the staggered magnetization. This precursor phenomenon entails, in ordinary nuclei, a showing down of the nuclear quasi-elastic response when observed with spin-sensitive probes. Permanent address: Istituto di Fisica Teorica dell'Università di Torino, Turin, Italy.

  8. Correlated model for quasi-elastic responses in finite nuclear systems

    CERN Document Server

    Có, G; Co', Giampaolo; Lallena, Antonio M.

    2001-01-01

    A model to calculate nuclear responses considering short-range correlation effects is presented. The model is applied to the study of electromagnetic responses induced by one-body operators. We calculate one- and two-nucleon emission responses and cross sections of the 16O and 40Ca nuclei in the quasi-elastic region, and we compare them with experimental data.

  9. Inclusive nucleon emission induced by quasi-elastic neutrino-nucleus interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nieves, J. [Departamento de Fisica Moderna, Universidad de Granada, E-18071, Granada (Spain); Valverde, M. [Departamento de Fisica Moderna, Universidad de Granada, E-18071, Granada (Spain); Vicente-Vacas, M.J. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Aptdo. 22085, E-46017 Valencia (Spain)

    2006-05-15

    A previous model on inclusive charged-current quasi-elastic nuclear reactions [J. Nieves, J.E. Amaro and M. Valverde, Phys. Rev. C 70 (2004) 055503] is extended to include neutral- and charged-current nucleon emission reactions. The problem of outgoing nucleon propagation is treated by means of a Monte Carlo simulation.

  10. Quasi-elastic neutron scattering study of the mobility of methane in microporous silica

    NARCIS (Netherlands)

    Benes, Nieck E.; Jobic, Herve; Verweij, Henk

    2001-01-01

    The dynamics of translation and rotation of methane in microporous bulk silica have been studied with quasi-elastic neutron scattering. At T=200 K the self-diffusion coefficient of translation is DS=1.1×10−8 m2 s−1 with an estimated activation energy of 4 kJ mol−1. Any variation of DS with occupanc

  11. Quasi-elastic neutron scattering studies of protein dynamics. Progress report, November 1, 1992--May 25, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Rorschach, H.E.

    1993-05-25

    Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.

  12. Measurement of Muon Antineutrino Quasi-Elastic Scattering on a Hydrocarbon Target at E_{\

    CERN Document Server

    Fields, L; Aliaga, L; Altinok, O; Bodek, A; Boehnlein, D; Bradford, R; Brooks, W K; Budd, H; Butkevich, A; Caicedo, D A M; Castromonte, C M; Christy, M E; da Motta, H; Damiani, D S; Danko, I; Datta, M; Day, M; DeMaat, R; Devan, J; Diaz, G A; Dytman, S A; Eberly, B; Edmondson, D A; Felix, J; Fitzpatrick, T; Fiorentini, G A; Gago, A M; Gallagher, H; Gobbi, B; Gran, R; Harris, D A; Higuera, A; Howley, I J; Hurtado, K; Jerkins, M; Kafka, T; Kanter, M O; Keppel, C; Kordosky, M; Krajeski, A H; Kulagin, S A; Le, T; Leister, A G; Maggi, G; Maher, E; Manly, S; Mann, W A; Marshall, C M; McFarland, K S; McGivern, C L; McGowan, A M; Mislivec, A; Morfin, J G; Mousseau, J; Naples, D; Nelson, J K; Niculescu, G; Niculescu, I; Ochoa, N; O'Connor, C D; Osta, J; Palomino, J L; Paolone, V; Park, J; Patrick, C E; Perdue, G N; Pena, C; Rakotondravohitra, L; Ransome, R D; Ray, H; Ren, L; Rodrigues, P A; Sassin, K E; Schellman, H; Schmitz, D W; Schneider, R M; Schulte, E C; Sedita, P; Simon, C; Snider, F D; Snyder, M C; Sobczyk, J T; Salinas, C J Solano; Tagg, N; Tan, W; Tice, B G; Tzanakos, G; Velasquez, J P; Walding, J; Walton, T; Wolcott, J; Wolthuis, B A; Zavala, G; Zhang, D; Ziemer, B P

    2013-01-01

    We have isolated muon anti-neutrino charged-current quasi-elastic interactions occurring in the segmented scintillator tracking region of the MINERvA detector running in the NuMI neutrino beam at Fermilab. We measure the flux-averaged differential cross-section, d{\\sigma}/dQ^2, and compare to several theoretical models of quasi-elastic scattering. Good agreement is obtained with a model where the nucleon axial mass, M_A, is set to 0.99 GeV/c^2 but the nucleon vector form factors are modified to account for the observed enhancement, relative to the free nucleon case, of the cross-section for the exchange of transversely polarized photons in electron-nucleus scattering. Our data at higher Q^2 favor this interpretation over an alternative in which the axial mass is increased.

  13. Quasi-elastic electron-deuteron scattering and the electric form factor of the neutron

    Energy Technology Data Exchange (ETDEWEB)

    Arenhoevel, H.; Kim, Y.E. (Mainz Univ. (Germany, F.R.). Inst. fuer Kernphysik); Craver, B.A. (Purdue Univ., Lafayette, IN (USA). Dept. of Physics); Fabian, W. (State Univ. of New York, Stony Brook (USA). Dept. of Physics); Saylor, D.P. (Worcester Polytechnic Inst., MA (USA). Dept. of Physics)

    1978-09-02

    The possibility of extracting accurately the neutron electric form factor from electron-neutron coincidence measurements in quasi-elastic electron-deuteron scattering is investigated for squared three-momentum transfers q/sup 2/<=30 fm/sup -2/ using the Reid soft-core, Hamada-Johnston and Bryan-Gersten potentials. It is found that contributions of the electric form factor of the neutron to the quasi-elastic cross section can be as large as 5.4% at q/sup 2/ approximately equal to 1 fm/sup -2/ (approximately 3% at q/sup 2/ approximately equal to 10 approximately 20 fm/sup 2/). Potential model dependence and corrections due to meson exchange currents and isobar configurations are found to be small (< or approximately 1%).

  14. A quasi-elastic neutron scattering and neutron spin-echo study of hydrogen bonded system

    Energy Technology Data Exchange (ETDEWEB)

    Branca, C.; Faraone, A.; Magazu, S.; Maisano, G.; Mangione, A

    2004-07-15

    This work reports neutron spin echo results on aqueous solutions of trehalose, a naturally occurring disaccharide of glucose, showing an extraordinary bioprotective effectiveness against dehydration and freezing. We collected data using the SPAN spectrometer (BENSC, Berlin) on trehalose aqueous solutions at different temperature values. The obtained findings are compared with quasi-elastic neutron scattering results in order to furnish new results on the dynamics of the trehalose/water system on the nano and picoseconds scale.

  15. Mobility of hydrogen in microporous silica studied with quasi-elastic neutron scattering

    NARCIS (Netherlands)

    Benes, Nieck E.; Jobic, Herve; Reat, Valerie; Bouwmeester, Henny J.M.; Verweij, Henk

    2003-01-01

    The mobility of H2 in microporous amorphous silica is studied using quasi-elastic neutron scattering. At T=90 K the self-diffusion coefficient is approximately Ds=1.2×10−8 m2 s−1 for low degrees of occupancy (<20%) and decreases slightly to Ds=0.95×10−8 m2 s−1 for an occupancy of 31%. A rough esti

  16. Quasi-elastic events and nuclear effects with the K2K Sci-Fi detector

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Christopher W. E-mail: walter@budoe.bu.edu

    2002-11-01

    The near detector complex of the K2K long-baseline neutrino experiment contains a scintillating fiber tracking detector. It is capable of detecting not only the muon but also the outgoing proton in neutrino-nucleon scattering. This allows for the enhancement of quasi-elastic interactions in the data sample. However, a proper modeling of the nuclear re-interactions of the proton is necessary to achieve reliable results.

  17. Quasi-elastic cross sections for 1GeV proton incident on {sup 4}He and {sup 12}C

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, M.; Nakamoto, T.; Shigyo, N. [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering] [and others

    1997-03-01

    The experiment of p-n quasi-elastic scattering cross sections was carried out for 1GeV protons on {sup 4}He and {sup 12}C. The coincident measurement was made at c.m. angles of {+-} 90deg. The experiment was simulated by the use of HETC (High Energy Transport Code). It was examined to apply the p-n quasi-elastic scattering cross sections to neutron flux measurement. (author)

  18. Quasi-elastic neutron scattering studies of protein dynamics. Final report, November 1, 1991--March 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.W.

    1995-04-10

    Proteins are formed from long polymer chains of amino acids that have been cross linked into a complex three dimensional structure. The structure is not unique, since there are many conformation substates of nearly equal energy, separated by small energy barriers, that are obtained by slight shifts in positions of various segments of the molecule. Transitions among these conformations substates are of a diffusive nature, and they can lead to substantial changes in the shape of the molecule. These changes in shape are important for the biological reactions in the cell. Such diffusive motion is inaccessible to the diffraction methods or to the computer simulations, since it occurs on a long time scale. It is accessible to incoherent quasi-elastic neutron scattering (QNS) studies, which permit a direct determination of the properties of the diffusive motion of the protons in the molecules. The authors have used the IQNS method to study the motions of the side chains in trypsin, a protein of beta-sheet structures and myoglobin, a protein of {alpha}-helical structures, at various D{sub 2}O hydration levels.

  19. A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment

    Science.gov (United States)

    Lyubushkin, V.; Popov, B.; Kim, J. J.; Camilleri, L.; Levy, J.-M.; Mezzetto, M.; Naumov, D.; Alekhin, S.; Astier, P.; Autiero, D.; Baldisseri, A.; Baldo-Ceolin, M.; Banner, M.; Bassompierre, G.; Benslama, K.; Besson, N.; Bird, I.; Blumenfeld, B.; Bobisut, F.; Bouchez, J.; Boyd, S.; Bueno, A.; Bunyatov, S.; Cardini, A.; Cattaneo, P. W.; Cavasinni, V.; Cervera-Villanueva, A.; Challis, R.; Chukanov, A.; Collazuol, G.; Conforto, G.; Conta, C.; Contalbrigo, M.; Cousins, R.; Daniels, D.; Degaudenzi, H.; Del Prete, T.; de Santo, A.; Dignan, T.; di Lella, L.; Do Couto E Silva, E.; Dumarchez, J.; Ellis, M.; Feldman, G. J.; Ferrari, R.; Ferrère, D.; Flaminio, V.; Fraternali, M.; Gaillard, J.-M.; Gangler, E.; Geiser, A.; Geppert, D.; Gibin, D.; Gninenko, S.; Godley, A.; Gomez-Cadenas, J.-J.; Gosset, J.; Gößling, C.; Gouanère, M.; Grant, A.; Graziani, G.; Guglielmi, A.; Hagner, C.; Hernando, J.; Hubbard, D.; Hurst, P.; Hyett, N.; Iacopini, E.; Joseph, C.; Juget, F.; Kent, N.; Kirsanov, M.; Klimov, O.; Kokkonen, J.; Kovzelev, A.; Krasnoperov, A.; Kulagin, S.; Kustov, D.; Lacaprara, S.; Lachaud, C.; Lakić, B.; Lanza, A.; La Rotonda, L.; Laveder, M.; Letessier-Selvon, A.; Ling, J.; Linssen, L.; Ljubičić, A.; Long, J.; Lupi, A.; Marchionni, A.; Martelli, F.; Méchain, X.; Mendiburu, J.-P.; Meyer, J.-P.; Mishra, S. R.; Moorhead, G. F.; Nédélec, P.; Nefedov, Yu.; Nguyen-Mau, C.; Orestano, D.; Pastore, F.; Peak, L. S.; Pennacchio, E.; Pessard, H.; Petti, R.; Placci, A.; Polesello, G.; Pollmann, D.; Polyarush, A.; Poulsen, C.; Rebuffi, L.; Rico, J.; Riemann, P.; Roda, C.; Rubbia, A.; Salvatore, F.; Samoylov, O.; Schahmaneche, K.; Schmidt, B.; Schmidt, T.; Sconza, A.; Seaton, M.; Sevior, M.; Sillou, D.; Soler, F. J. P.; Sozzi, G.; Steele, D.; Stiegler, U.; Stipčević, M.; Stolarczyk, Th.; Tareb-Reyes, M.; Taylor, G. N.; Tereshchenko, V.; Toropin, A.; Touchard, A.-M.; Tovey, S. N.; Tran, M.-T.; Tsesmelis, E.; Ulrichs, J.; Vacavant, L.; Valdata-Nappi, M.; Valuev, V.; Vannucci, F.; Varvell, K. E.; Veltri, M.; Vercesi, V.; Vidal-Sitjes, G.; Vieira, J.-M.; Vinogradova, T.; Weber, F. V.; Weisse, T.; Wilson, F. F.; Winton, L. J.; Wu, Q.; Yabsley, B. D.; Zaccone, H.; Zuber, K.; Zuccon, P.

    2009-10-01

    We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions ( ν μ n→ μ - p and bar{ν }_{μ}ptoμ+n ) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total ν μ ( bar{ν}_{μ} ) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3-100 GeV are < σ_{qel}rangle_{ν_{μ}}=(0.92±0.02(stat)±0.06(syst))×10^{-38} cm2 and <σ_{qel}rangle_{bar{ν}_{μ}}=(0.81±0.05(stat)±0.09(syst))×10^{-38} cm2 for neutrino and antineutrino, respectively. The axial mass parameter M A was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M A =1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure Q 2 shape analysis of the high purity sample of ν μ quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured M A is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M A is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M A , these results are compatible with the more precise NOMAD value.

  20. Analysis of the Quasi-Elastic Scattering of Neutrons in Hydrogenous Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Porohit, S.N. [Nuclear Science and Engineering Dept., Rensselaer Polytechnique Inst., Troy, NY (United States)

    1966-11-15

    A critical discussion of the quasi-elastic scattering of neutrons by incoherent (hydrogenous) liquids is presented. Using the line shape expression a comparative discussion of several phenomenological models has been carried out. Extension of the Singwi-Sjoelander zero phonon expression, for the jump-diffusion model, so as to include the one phonon expression has also been given. For a delayed diffusion model a complete treatment of S(K, {omega}) is presented. Along the lines of the macroscopic diffusion cooling, a microscopic diffusion cooling effect in fluids is speculated.

  1. Chiral symmetry, constituent quarks and quasi-elastic electron-nucleus scattering

    Science.gov (United States)

    Henley, E. M.; Krein, G.

    1989-11-01

    The effects of chiral symmetry breaking are examined for quasi-elastic electron scattering on nuclei. Nucleons are assumed to be composed of constituent quarks with masses that depend on density. This density dependence is determined on the basis of the Nambu-Jona-Lasinio model. It is found that the effects of chiral symmetry breaking are in the right direction and the right order of magnitude to explain the discrepancies between theory and experiment. On leave from Departamento de Fisica, Universidade Federal de Santa Maria, 97100 Santa Maria, R.S., Brazil.

  2. Tensor Analyzing Powers for Quasi-Elastic Electron Scattering from Deuterium

    CERN Document Server

    Zhou, Z L; Ferro-Luzzi, M; Passchier, E; Alarcon, R; Anghinolfi, M; Arenhövel, H; Van Bommel, R; Botto, T; Van den Brand, J F J; Bulten, H J; Choi, S; Comfort, J; Dolfini, S M; Ent, R; Gaulard, C; Higinbotham, D W; De Jager, C W; Konstantinov, E S; Lang, J; Leidemann, W; De Lange, D J; Miller, M A; Lenko, D N; Papadakis, N H; Passchier, I; Poolman, H R; Popov, S G; Rachek, Igor A; Ripani, M; Six, E; Steijger, J J M; Taiuti, M; Unal, O; Vodinas, N P; De Vries, H

    1999-01-01

    We report on a first measurement of tensor analyzing powers in quasi-elastic electron-deuteron scattering at an average three-momentum transfer of 1.7 fm$^{-1}$. Data sensitive to the spin-dependent nucleon density in the deuteron were obtained for missing momenta up to 150 MeV/$c$ with a tensor polarized $^2$H target internal to an electron storage ring. The data are well described by a calculation that includes the effects of final-state interaction, meson-exchange and isobar currents, and leading-order relativistic contributions.

  3. Short Range Correlations in Nuclei at Large xbj through Inclusive Quasi-Elastic Electron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhihong [Univ. of Virginia, Charlottesville, VA (United States)

    2013-12-01

    The experiment, E08-014, in Hall-A at Jefferson Lab aims to study the short-range correlations (SRC) which are necessary to explain the nuclear strength absent in the mean field theory. The cross sections for 2H, 3He, 4He, 12C, 40Ca and 48Ca, were measured via inclusive quasi-elastic electron scattering from these nuclei in a Q2 range between 0.8 and 2.8 (GeV/c)2 for x>1. The cross section ratios of heavy nuclei to 2H were extracted to study two-nucleon SRC for 1

  4. Inverse freezing in {alpha}-cyclodextrin solutions probed by quasi elastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Plazanet, M. [LENS, University of Florence, Via Nello Carrara 1, I-50019 Sesto-Fiorentino (Italy); INFM-CRS-Soft Matter (CNR), c/o Univ. la Sapienza, Piaz. A. Moro 2, I-00185 Roma (Italy); Institut Laue-Langevin, B.P. 156X, 38042 Grenoble Cx (France); Johnson, M.R. [Institut Laue-Langevin, B.P. 156X, 38042 Grenoble Cx (France); Schweins, R. [Institut Laue-Langevin, B.P. 156X, 38042 Grenoble Cx (France); Trommsdorff, H.P. [Institut Laue-Langevin, B.P. 156X, 38042 Grenoble Cx (France); Laboratoire de Spectrometrie Physique, Universite J. Fourier Grenoble - CNRS (UMR 5588), BP 87, 38402 St. Martin d' Heres Cx (France)], E-mail: trommsdorff@ill.fr

    2006-12-11

    Solutions of {alpha}-cyclodextrin, 4-methylpyridine and water undergo a reversible liquid-solid phase transition on heating ('inverse freezing'). In this paper quasi elastic neutron scattering (QENS) measurements are reported, from which the diffusive dynamics of different components in the liquid and solid phases is determined. Results imply that, in solution, {alpha}-cyclodextrin is contained in a solvation shell of 4-methylpyridine molecules, while in the crystal phase, the majority of the cell contents are immobilized on the nanosecond timescale. This information will be important in evaluating the entropy of the system in its different phases and in understanding the unusual phase transition.

  5. Structure information from fusion barriers

    Indian Academy of Sciences (India)

    S V S Sastry; S Santra

    2000-06-01

    It is shown that the analysis of fusion barrier distributions is not always an unambiguous test or a ‘fingerprint’ of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for 16O+208Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed. The barrier distributions derived from these excitation functions including many of the significant channels are featureless, although these channels have considerable effects on the fusion excitation function. However, a simultaneous analysis of the fusion, elastic and quasi-elastic channels would fix the structure and the reaction unambiguously

  6. A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lyubushkin, V.; Bunyatov, S.; Chukanov, A.; Klimov, O.; Kustov, D.; Nefedov, Yu.; Samoylov, O.; Tereshchenko, V. [JINR, Dubna (Russian Federation); Popov, B. [JINR, Dubna (Russian Federation); LPNHE, Univ. of Paris VI and VII, Paris (France); Kim, J.J.; Godley, A.; Ling, J.; Mishra, S.R.; Petti, R.; Seaton, M.; Wu, Q. [Univ. of South Carolina, Columbia, SC (United States); Camilleri, L.; Autiero, D.; Di Lella, L.; Couto e Silva, E. do; Ferrere, D.; Grant, A.; Kokkonen, J.; Linssen, L.; Placci, A.; Stiegler, U.; Tsesmelis, E.; Vidal-Sitjes, G.; Wilson, F.F. [CERN, Geneva (Switzerland); Levy, J.M.; Astier, P.; Banner, M.; Dumarchez, J.; Lachaud, C.; Letessier-Selvon, A.; Schahmaneche, K.; Touchard, A.M.; Vannucci, F. [LPNHE, Univ. of Paris VI and VII, Paris (France); Mezzetto, M.; Baldo-Ceolin, M.; Bobisut, F.; Collazuol, G.; Contalbrigo, M.; Gibin, D.; Guglielmi, A.; Lacaprara, S.; Laveder, M.; Rebuffi, L.; Sconza, A.; Zuccon, P. [Univ. of Padova (Italy); INFN, Padova (Italy); Naumov, D. [JINR, Dubna (Russian Federation); Univ. of Florence (Italy); INFN, Florence (Italy); Alekhin, S. [Inst. for High Energy Physics, Protvino, Moscow Region (Russian Federation); Baldisseri, A.; Besson, N.; Bouchez, J.; Gosset, J.; Hagner, C.; Mechain, X.; Meyer, J.P.; Stolarczyk, T.; Zaccone, H. [DAPNIA, Saclay (France); Bassompierre, G.; Gaillard, J.M.; Gouanere, M.; Mendiburu, J.P.; Nedelec, P.; Pessard, H.; Sillou, D. [LAPP, Annecy (France); Benslama, K.; Degaudenzi, H.; Joseph, C.; Juget, F.; Nguyen-Mau, C.; Sozzi, G.; Tareb-Reyes, M.; Tran, M.T.; Vacavant, L.; Vieira, J.M. [Univ. of Lausanne, Lausanne (Switzerland); Bird, I. [CERN, Geneva (Switzerland); Univ. of Lausanne (Switzerland); Blumenfeld, B.; Long, J. [Johns Hopkins Univ., Baltimore, MD (United States); Boyd, S.; Ellis, M.; Peak, L.S.; Ulrichs, J.; Varvell, K.E.; Yabsley, B.D. [Univ. of Sydney (Australia); Bueno, A. [Harvard Univ., Cambridge, MA (United States); ETH Zurich (Switzerland)] [and others

    2009-10-15

    We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions ({nu}{sub {mu}}n {yields}{mu}{sup -}p and anti {nu}{sub {mu}}p{yields}{mu}{sup +}n) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total {nu}{sub {mu}}(anti {nu}{sub {mu}}) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3-100 GeV are left angle {sigma}{sub qel} right angle {sub {nu}}{sub {mu}}=(0.92{+-}0.02(stat){+-}0.06(syst)) x 10{sup -38} cm{sup 2} and left angle {sigma}{sub qel} right angle {sub anti} {sub {nu}{sub {mu}}}{sub =}(0.81{+-}0.05(stat){+-}0.09(syst)) x 10{sup -38} cm{sup 2} for neutrino and antineutrino, respectively. The axial mass parameter M{sub A} was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M{sub A}=1.05{+-}0.02(stat){+-}0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure Q{sup 2} shape analysis of the high purity sample of {nu}{sub {mu}} quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured M{sub A} is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M{sub A} is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M{sub A}, these results are compatible with the more precise NOMAD value. (orig.)

  7. Measurement of Muon Neutrino Quasi-Elastic Scattering on a Hydrocarbon Target at E_{\

    CERN Document Server

    Fiorentini, G A; Rodrigues, P A; Aliaga, L; Altinok, O; Bodek, A; Boehnlein, D; Bradford, R; Brooks, W K; Budd, H; Butkevich, A; Caicedo, D A M; Castromonte, C M; Christy, M E; Chvojka, J; da Motta, H; Damiani, D S; Danko, I; Datta, M; Day, M; DeMaat, R; Devan, J; Diaz, G A; Dytman, S A; Eberly, B; Edmondson, D A; Felix, J; Fields, L; Fitzpatrick, T; Gago, A M; Gallagher, H; Gobbi, B; Gran, R; Harris, D A; Higuera, A; Howley, I J; Hurtado, K; Jerkins, M; Kafka, T; Kanter, M O; Keppel, C; Kordosky, M; Krajeski, A H; Kulagin, S A; Le, T; Leister, A G; Maggi, G; Maher, E; Manly, S; Mann, W A; Marshall, C M; McFarland, K S; McGivern, C L; McGowan, A M; Mislivec, A; Morfin, J G; Mousseau, J; Naples, D; Nelson, J K; Niculescu, G; Niculescu, I; Ochoa, N; O'Connor, C D; Osta, J; Palomino, J L; Paolone, V; Park, J; Patrick, C E; Perdue, G N; Pena, C; Rakotondravohitra, L; Ransome, R D; Ray, H; Ren, L; Sassin, K E; Schellman, H; Schneider, R M; Schulte, E C; Sedita, P; Simon, C; Snider, F D; Snyder, M C; Sobczyk, J T; Salinas, C J Solano; Tagg, N; Tan, W; Tice, B G; Tzanakos, G; Velasquez, J P; Walding, J; Walton, T; Wolcott, J; Wolthuis, B A; Zavala, G; Zhang, D; Ziemer, B P

    2013-01-01

    We report a study of muon neutrino charged-current quasi-elastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a {\\mu}^- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross-section, d{\\sigma}/dQ^2, and study the low energy particle content of the final state. Deviations are found between the measured d{\\sigma}/dQ^2 and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.

  8. Extraction of structure functions for lepton-nucleus scattering in the quasi-elastic region

    Science.gov (United States)

    Kim, K. S.; Kim, Hungchong; Cheoun, Myung-Ki; So, W. Y.

    2016-12-01

    Within the framework of a relativistic single-particle model, we calculate inclusive electron-nucleus scattering by electromagnetic current, and neutrino-nucleus scattering by neutral and charged current in the quasi-elastic region. The longitudinal, the transverse, and the transverse-interference structure functions are extracted from the theoretical cross section by using the Rosenbluth separation method at fixed momentum transfer and scattering angle and then compared with each other from the viewpoint of these current interactions. The position of peak for the electron scattering shifts to higher energy transfer than that for the neutrino scattering. The axial and pseudoscalar terms turn out to play an important role in the neutrino-nucleus scattering.

  9. mQfit, a new program for analyzing quasi-elastic neutron scattering data

    Directory of Open Access Journals (Sweden)

    Martinez Nicolas

    2015-01-01

    Full Text Available Analysis of Quasi-elastic Neutron Scattering (QENS data of complex systems such as biological or soft matter samples in a comprehensive and explicit way often requires great efforts. Most popular software only allows to fit spectra originating from one single instrument and does not permit to extract parameters from a model that is fitted simultaneously to data taken at different instrumental resolutions. We present here a new program, mQfit (multiple QENS dataset fitting, that enables to fit QENS data taken at different spectrometers (with typical resolutions between 0.01 and 0.1 meV and momentum transfer ranges. This allows drastically reducing the number of fitting parameters. The routine is implemented with a user friendly Graphical User's Interface (GUI, and freely available. As an example, we will present results obtained on E. coli bacterial pellets, and compare them to values published in the literature.

  10. Quasi-elastic neutron scattering study of dynamics in condensed matter

    Indian Academy of Sciences (India)

    S Mitra; R Mukhopadhyay

    2004-07-01

    Quasi-elastic neutron scattering (QENS) technique, known to study stochastic motions has been successfully used to elucidate the molecular motions and physical properties related to them, in a variety of systems. QENS is a unique technique that provides information on the time-scale of the motion as well as the geometry of the motions. In this paper, results of some of the systems studied using the facility available at Dhruva, Trombay and other mega-facilities are discussed. Emphasis is given on the results obtained from three different systems studied using QENS, namely, (1) alkyl chain motions in monolayer protected metal clusters, (2) molecular motions of propane in Na-Y zeolitic systems and (3) the study of reorientational motions of liquid crystal in O. series in different mesophases.

  11. Quasi-elastic light scattering of platinum dendrimer-encapsulated nanoparticles.

    Science.gov (United States)

    Wales, Christina H; Berger, Jacob; Blass, Samuel; Crooks, Richard M; Asherie, Neer

    2011-04-05

    Platinum dendrimer-encapsulated nanoparticles (DENs) containing an average 147 atoms were prepared within sixth-generation, hydroxyl-terminated poly(amidoamine) dendrimers (G6-OH). The hydrodynamic radii (R(h)) of the dendrimer/nanoparticle composites (DNCs) were determined by quasi-elastic light scattering (QLS) at high (pH ∼10) and neutral pH for various salt concentrations and identities. At high pH, the size of the DNC (R(h) ∼4 nm) is close to that of the empty dendrimer. At neutral pH, the size of the DNC approximately doubles (R(h) ∼8 nm) whereas that of the empty dendrimer remains unchanged. Changes in ionic strength also alter the size of the DNCs. The increase in size of the DNC is likely due to electrostatic interactions involving the metal nanoparticle.

  12. Eikonal analysis of Coulomb distortion in quasi-elastic electron scattering

    CERN Document Server

    Tjon, J A

    2008-01-01

    An eikonal expansion is used to provide systematic corrections to the eikonal approximation through order $1/k^2$, where $k$ is the wave number. Electron wave functions are obtained for the Dirac equation with a Coulomb potential. They are used to investigate distorted-wave matrix elements for quasi-elastic electron scattering from a nucleus. A form of effective-momentum approximation is obtained using trajectory-dependent eikonal phases and focusing factors. Fixing the Coulomb distortion effects at the center of the nucleus, the often-used ema approximation is recovered. Comparisons of these approximations are made with full calculations using the electron eikonal wave functions. The ema results are found to agree well with the full calculations.

  13. Quasi-elastic laser light scattering study of polyacrylamide hydrogel immersed in water and salt solutions

    Indian Academy of Sciences (India)

    M Sivanantham; B V R Tata

    2010-12-01

    Polyacrylamide (PAAm) hydrogels immersed in water and aqueous NaCl solutions were investigated for their structure and dynamics using static and quasi-elastic laser light scattering (QELS) techniques. Ensemble-averaged electric field correlation function (, ) obtained from the non-ergodic analysis of intensity-autocorrelation function for PAAm gel immersed in water and in 5 M NaCl showed an exponential decay to a plateau with an initial decay followed by saturation at long times. The value of the plateau was found to depend on NaCl concentration and was higher than that of water. Collective diffusion coefficient, , of the polymer network of the hydrogel immersed in water and in different concentrations of NaCl was determined by analysing (, ). The measured diffusion coefficient showed linear decrease with increase in concentration of NaCl. The characteristic network parameters were obtained by analyzing (, ) with harmonically bound Brownian particle model and from static light scattering studies.

  14. Search for neutrino oscillations in the MINOS experiment by using quasi-elastic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Piteira, Rodolphe [Univ. Pierre et Marie Curie, Paris (France)

    2005-09-29

    The enthusiasm of the scientific community for studying oscillations of neutrinos is equaled only by the mass of their detectors. The MINOS experiment determines and compares the near spectrum of muonic neutrinos from the NUMI beam to the far one, in order to measure two oscillation parameters: Δm$2\\atop{23}$ and sin2 (2θ23). The spectra are obtained by analyzing the charged current interactions which difficulty lies in identifying the interactions products (e.g. muons). An alternative method identifying the traces of muons, bent by the magnetic field of the detectors, and determining their energies is presented in this manuscript. The sensitivity of the detectors is optimal for the quasi-elastic interactions, for which a selection method is proposed, to study their oscillation. Even though it reduces the statistics, such a study introduces fewer systematic errors, constituting the ideal method on the long range.

  15. The effects of density-dependent form factors for (e, e'p) reaction in quasi-elastic region

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.S. [Korea Aerospace University, School of Liberal Arts and Science, Goyang (Korea, Republic of); Cheoun, Myung-Ki [Soongsil University, Department of Physics, Seoul (Korea, Republic of); Kim, Hungchong [Kookmin University, Department of General Education, Seoul (Korea, Republic of); So, W.Y. [Kangwon National University at Dogye, Department of Radiological Science, Samcheok (Korea, Republic of)

    2016-04-15

    Within the framework of a relativistic single particle model, the effects of density-dependent electromagnetic form factors on the exclusive (e, e'p) reaction are investigated in the quasi-elastic region. The density-dependent electromagnetic form factors are generated from a quark-meson coupling model and used to calculate the cross sections in two different densities, either at the normal density of ρ{sub 0} ∝ 0.15 fm{sup -3} or at the lower density, 0.5ρ{sub 0}. Then these cross sections are analyzed in the two different kinematics: One is that the momentum of the outgoing nucleon is along the momentum transfer. The other is that the angle between the momentum of the outgoing nucleon and the momentum transfer is varied at fixed magnitude of the momentum of the outgoing nucleon. Our theoretical differential reduced cross sections are compared with the NIKHEF data for the {sup 208}Pb(e, e'p) reaction, which is related to the probability that a bound nucleon from a given orbit can be knocked-out of the nucleus. The effects of the density-dependent form factors increase the differential cross sections for both knocked-out proton and neutron by an amount of a few percent. Moreover they are shown to be almost the same within only a few percent, i.e., nearly independent of the shell location of knockout nucleons. These results are quite consistent with the characteristics of double magic nuclei which have relatively sharp smearing in the density distribution. (orig.)

  16. A sub-GeV charged-current quasi-elastic $\

    Energy Technology Data Exchange (ETDEWEB)

    Walding, Joseph James [Imperial College, London (United Kingdom)

    2009-12-01

    Neutrino-nucleus charged-current quasi-elastic scattering is the signal interaction used by many neutrino oscillation experiments. For muon disappearance studies the signal mode is νμn → μp. Modern oscillation experiments, such as T2K, produce neutrino beams with peak beam energies of order a few-GeV. It is therefore vitally important to have accurate measurements of the charged-current quasi-elastic crosssection for future neutrino oscillation experiments. Neutrino-nucleus cross-sections in the few-GeV region are not well understood, with the main uncertainties coming from understanding of the neutrino beam flux and the final state interactions within nuclei. SciBooNE is a sub-GeV neutrino-nucleus cross-section experiment based at Fermilab, Batavia, USA, with the goal to measure neutrino cross-sections with precision of order 5%. SciBooNE took data from June 2007 until August 2008, in total 0.99×1020 and 1.53×1020 protons on target were collected in neutrino and anti-neutrino mode, respectively. In this thesis a νμ charged-current quasi-elastic (CCQE) cross-section contained within the SciBar sub-detector is presented. A method to tag muons in SciBar was developed and three samples were isolated. An excess in backwards tracks in the one-track sample is observed. A Poisson maximum likelihood is used to extract the CCQE cross-section. The fit was applied using a basic fit parameter model, successfully used to obtain the cross-section in the SciBar-MRD matched CCQE analysis. This method was found to be insufficient in describing the data for the SciBarcontained CCQE analysis. By adding two migration parameters the cross-section was calculated to be 1.004 ± 0.031 (stat)+0.101 -0.150(sys) × 10-38 cm2/neutron, excluding backwards tracks with a χ2 = 203.8/76 d.o.f. and 1.083 ± 0.030(stat)+0.115 -0.177(sys) × 10-38 cm2

  17. Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

    Science.gov (United States)

    Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin

    2012-02-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χT(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter α2 extracted from the elastic scattering.

  18. The Measurement of Neutrino Induced Quasi-Elastic Cross Section In NOMAD

    CERN Document Server

    Kim, Jae Jun

    2010-01-01

    NOMAD (Neutrino Oscillation MAgnetic Detector) was a short baseline neutrino experiment conducted at CERN (the European Laboratory for Particle physics) West Area Neutrino Facility (WANF) with a neutrino beam provided by the super proton synchrotron (SPS) accelerator. In this dissertation, we present a measurement of muon-neutrino induced quasi-elastic cross section and its axial-mass off an isoscalar target in the NOMAD detector. The incident neutrino energy in NOMAD experiment spans from 2.5 to 300 GeV. The measurement of cross-section is conducted in two seperate kinematic-based topology, two-track and one-track topologies, where a proton is not properly reconstructed. The QEL cross-section as a function of the incoming neutrino energy is consistent for the two different topologies, and within errors , constant as a function of the neutrino energy. We determine the energy-averaged cross-section. From the shape-comparisons of kinematics of QEL-like events, the parameter of QEL axial mass is estimated. It i...

  19. The contribution of small angle and quasi-elastic scattering to the physics of liquid water

    Science.gov (United States)

    Teixeira, José

    2017-05-01

    Many properties of liquid water at low temperature show anomalous behaviour. For example, density, isothermal compressibility, heat capacity pass by maxima or minima and transport properties show a super-Arrhenius behaviour. Extrapolations performed beyond the homogeneous nucleation temperature are at the origin of models that predict critical points, liquid-liquid transitions or dynamic cross-overs in the large domain of temperature and pressure not accessible to experiments because of ice nucleation. A careful analysis of existing data can be used to test some of these models. Small angle X-ray or neutron scattering data are incompatible with models where two liquids or heterogeneities are present. Quasi-elastic neutron scattering, taking advantage and combining both coherent and incoherent scattering show that two relaxation times are present in liquid water and that one of them, related to hydrogen bond dynamics, has an Arrhenian behaviour, suggesting that the associated dynamics of the bonds, similar to the β relaxation of polymers, determines the glass transition temperature of water.

  20. Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang [ORNL; Tyagi, M. [NCNR and University of Maryland; Mamontov, Eugene [ORNL; Chen, Sow-hsin H [ORNL

    2011-01-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.

  1. Anti-Neutrino Charged Current Quasi-Elastic Scattering in MINER$\

    Energy Technology Data Exchange (ETDEWEB)

    Chvojka, Jesse John [Univ. of Rochester, NY (United States)

    2012-01-01

    The phenomenon of neutrino oscillation is becoming increasingly understood with results from accelerator-based and reactor-based experiments, but unanswered questions remain. The proper ordering of the neutrino mass eigenstates that compose the neutrino avor eigenstates is not completely known. We have yet to detect CP violation in neutrino mixing, which if present could help explain the asymmetry between matter and anti-matter in the universe. We also have not resolved whether sterile neutrinos, which do not interact in any Standard Model interaction, exist. Accelerator-based experiments appear to be the most promising candidates for resolving these questions; however, the ability of present and future experiments to provide answers is likely to be limited by systematic errors. A significant source of this systematic error comes from limitations in our knowledge of neutrino-nucleus interactions. Errors on cross-sections for such interactions are large, existing data is sometimes contradictory, and knowledge of nuclear effects is incomplete. One type of neutrino interaction of particular interest is charged current quasi-elastic (CCQE) scattering, which yields a final state consisting of a charged lepton and nucleon. This process, which is the dominant interaction near energies of 1 GeV, is of great utility to neutrino oscillation experiments since the incoming neutrino energy and the square of the momentum transferred to the final state nucleon, Q2, can be reconstructed using the final state lepton kinematics. To address the uncertainty in our knowledge of neutrino interactions, many experiments have begun making dedicated measurements. In particular, the MINER A experiment is studying neutrino-nucleus interactions in the few GeV region. MINERvA is a fine-grained, high precision, high statistics neutrino scattering experiment that will greatly improve our understanding of neutrino cross-sections and nuclear effects that affect the final state particles

  2. Green's function Monte Carlo calculations of the electromagnetic and neutral-weak response functions in the quasi-elastic sector

    CERN Document Server

    Lovato, Alessandro

    2016-01-01

    A quantitative understanding of neutrino-nucleus interactions is demanded to achieve precise measurement of neutrino oscillations, and hence the determination of their masses. In addition, next generation detectors will be able to detect supernovae neutrinos, which are likely to shed some light on the open questions on the dynamics of core collapse. In this context, it is crucial to account for two-body meson-exchange currents along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on the Green's function Monte Carlo method, that can be exploited to accurately describe neutrino interactions with atomic nuclei in the quasi-elastic sector.

  3. Recent Advances and Open Questions in Neutrino-induced Quasi-elastic Scattering and Single Photon Production

    Energy Technology Data Exchange (ETDEWEB)

    Garvey, G. T. [Los Alamos; Harris, D. A. [Fermilab; Tanaka, H. A. [British Columbia U.; Tayloe, R. [Indiana U.; Zeller, G. P. [Fermilab

    2015-06-15

    The study of neutrino–nucleus interactions has recently seen rapid development with a new generation of accelerator-based neutrino experiments employing medium and heavy nuclear targets for the study of neutrino oscillations. A few unexpected results in the study of quasi-elastic scattering and single photon production have spurred a revisiting of the underlying nuclear physics and connections to electron–nucleus scattering. A thorough understanding and resolution of these issues is essential for future progress in the study of neutrino oscillations.

  4. Results for quasi-elastic anti-neutrino scattering on scintillator from the MINERvA experiment

    Science.gov (United States)

    Schellman, Heidi; Minerva Collaboration

    2016-09-01

    We present a new preliminary measurement of the charge-current quasi-elastic scattering cross section for anti-neutrinos on scintillator (CH) over the energy range 1.5-10 GeV. The data were taken with the MINERvA detector in the NuMI beamline at Fermilab and cover the energy range of interest for the proposed DUNE long-baseline neutrino oscillation experiment and of JLAB elastic scattering experiments. Of particular interest to the nuclear community are possible signatures for short range correlations and/or meson exchange currents in these data. We present comparisons to a range of nuclear models.

  5. Quasi-Elastic Neutron Scattering (QENS) Studies of Hydrogen Dynamics for Nano-Confined NaAlH4

    Science.gov (United States)

    Dobbins, Tabbetha; Narasegowda, Shathabish; Brown, Craig; Tyagi, Madhusudan; Jenkins, Timothy

    The hydrogen dynamics of nano-confined sodium alanate (NaAlH4) has been studied using quasi-elastic neutron scattering (QENS). Results indicate thermodynamic destabilization is responsible for reduced desorption temperatures of NaAlH4 upon confinement within the nanopores of a metal organic framework (MOF). Both the bulk (microscale) NaAlH4 and the nanoconfined NaAlH4 data were fitted to re-orientation models which yielded corresponding percent mobile hydrogen and jump lengths. The jump lengths calculated from the nano-NaAlH4 were ~2.5 Å, and in conformity with those jump lengths determined for bulk NaAlH4 of ~2.3 Å. As much as 18 % of the hydrogen atoms were estimated to be mobile in the nano-NaAlH4 sample even at relatively low temperatures of 350 K. In contrast, bulk NaAlH4 shows less than 7 % mobile H-atoms even at higher temperatures of ~450 K. The activation energy for the long range is 3.1meV. Quasi-Elastic Neutron Scattering (QENS) Studies of Hydrogen Dynamics for Nano-Confined NaAlH4.

  6. Beam-target double spin asymmetry in quasi-elastic electron scattering off the deuteron with CLAS

    CERN Document Server

    Mayer, Michael

    2016-01-01

    Quasi-elastic electron scattering on the deuteron is a benchmark reaction to test our understanding of deuteron structure and the properties and interactions of the two nucleons bound in the deuteron. The experimental data presented here can be used to test state-of-the-art models of the deuteron and the two-nucleon interaction in the final state after two-body breakup of the deuteron. Focusing on polarization degrees of freedom, we gain information on spin-momentum correlations in the deuteron ground state (due to the D-state admixture) and on the limits of the Impulse Approximation (IA) picture as it applies to measurements of spin-dependent observables like spin structure functions for bound nucleons. We measured the beam-target double spin asymmetry for quasi-elastic electron scattering off the deuteron at several beam energies using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The deuterons were polarized along (or opposite to) the beam direction. ...

  7. Meaurement of the target single-spin asymmetry in quasi-elastic region from the reaction {sup 3}He{up_arrow}(e,e')

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yawei [Rutgers

    2013-10-01

    A measurement of the inclusive target single-spin asymmetry has been performed using the quasi-elastic {sup 3}He{up_arrow}(e,e') reaction with a vertically polarized {sup 3}He target at Q{sup 2} values of 0.13, 0.46 and 0.97 GeV{sup 2}. This asymmetry vanishes under the one photon exchange assumption. But the interference between two-photon exchange and one-photon exchange gives rise to an imaginary amplitude, so that a non-zero A{sub y} is allowed. The experiment, conducted in Hall A of Jefferson Laboratory in 2009, used two independent spectrometers to simultaneously measure the target single-spin asymmetry. Using the effective polarization approximation, the neutron single-spin asymmetries were extracted from the measured {sup 3}He asymmetries. The measurement is to establish a non-vanishing A{sub y}. Non-zero asymmetries were observed at all Q{sup 2} points, and the overall precision is an order of magnitude improved over the existing proton data. The data provide new constraints on Generalized Parton Distribution (GPD) models and new information on the dynamics of the two-photon exchange process.

  8. Experimental study of quasi-elastic neutrino interactions on Ar with a liquid Ar TPC exposed to the WANF neutrino beam

    CERN Document Server

    Curioni, A

    2006-01-01

    We present results from the first exposure of a liquid Ar time projection chamber to a neutrino beam. The data have been collected in 1997 with a 50 liter ICARUS-like chamber located between the CHORUS and NOMAD experiment at the CERN West Area Neutrino Facility. We focus on the analysis of quasi-elastic interactions; despite the limited size of the detector, nuclear effects beyond Fermi motion and Pauli blocking have been observed as perturbations to the pure quasi-elastic kinematics.

  9. Effects of Citral on Aspergillus flavus Spores by Quasi-elastic Light Scattering and Multiplex Microanalysis Techniques

    Institute of Scientific and Technical Information of China (English)

    Man LUO; Li-Ke JIANG; Yao-Xiong HUANG; Ming XIAO; Bo LI; Guo-Lin ZOU

    2004-01-01

    Citral refined from Litsea cubeba oil has been found to have a strong influence on fungi,especially Aspergillus flavus. Multiplex microanalysis and quasi-elastic light scattering techniques were applied to study the effects of citral on Aspergillus flavus spores from the levels of membrane, organelle and intracellular macromolecule. It was found that citral injured the wall and the membrane of A. flavus spore,resulting in decrease of its elasticity. After entering the cell, citral not only influenced the genetic expression of mitochondrion reduplication and its morphology, but also changed the aggregation of protein-like macromolecules. As a result, cells, organelles and macromolecules lost their normal structures and functions,eventually leading to the loss of germination ability of A. flavus spores. Since Litsea cubeba oil as food additive and antifungal agent is safe and less poisonous, it is important to elucidate the inhibitory mechanisms of Litsea cubeba oil on the germination ability ofA. flavus spore.

  10. Muon spectra of Quasi-Elastic and 1-pion production events at the KEK LBL neutrino oscillation experiment

    CERN Document Server

    Yu, J Y; Roy, D P; Schienbein, I; Yu, Ji--Young

    2003-01-01

    We present predictions for the flux averaged muon energy spectra of quasi-elastic (QE) and 1-pion production events for the K2K long-baseline experiment. Using the general kinematical considerations we show that the muon energy spectra closely follow the neutrino energy spectrum with downward shift of the energy scale by 0.15 GeV (QE) and 0.4 GeV (1-pion production). These predictions seem to agree with the observed muon energy spectra in the K2K nearby detector. We also show the spectral distortion of these muon energy spectra due to the neutrino oscillation for the SK detector. Comparison of the predicted spectral distortions with the observed muon spectra of the 1-Ring and 2-Ring muon events in the SK detector will help to determine the oscillation parameters. The results will be applicable to other LBL experiments as well.

  11. Uncontained νμ charged-current quasi-elastic events at the NOvA far detector

    Science.gov (United States)

    Sepulveda-Quiroz, Jose; NOvA Collaboration

    2017-01-01

    NOvA is a long-baseline neutrino oscillation experiment that uses an upgraded neutrino beam from Fermilab and two highly active, segmented, liquid scintillator off-axis detectors that offer a remarkable capability in event identification. In its first and second analysis results, NOvA has used only events with an interaction vertex and all secondary particles fully contained in the detectors. I will present studies of the potential sensitivity improvement of the sin2 2θ23 and Δm322 neutrino oscillation parameters from the νμ-disappearance measurement when including uncontained events in the sample. In particular, this study focuses on incorporating νμ charged current quasi-elastic interactions of the type νμ + n -> μ + p where the muon is uncontained but the proton is contained.

  12. Static and quasi-elastic small angle neutron scattering on biocompatible ionic ferrofluids: magnetic and hydrodynamic interactions

    CERN Document Server

    Gazeau, F; Dubois, E; Perzynski, R

    2003-01-01

    We investigate the structure and dynamics of ionic magnetic fluids (MFs), based on ferrite nanoparticles, dispersed at pH approx 7 either in H sub 2 O or in D sub 2 O. Polarized and non-polarized static small angle neutron scattering (SANS) experiments in zero magnetic field allow us to study both the magnetic and the nuclear contributions to the neutron scattering. The magnetic interparticle attraction is probed separately from the global thermodynamic repulsion and compares well to direct magnetic susceptibility measurements. The magnetic interparticle correlation is in these fluid samples independent of the probed spatial scale. In contrast, a spatial dependence of the interparticle correlation is evidenced at large PHI by the nuclear structure factor. A model of magnetic interaction quantitatively explains the under-field anisotropy of the SANS nuclear contribution. In a quasi-elastic neutron spin-echo experiment, we probe the Brownian dynamics of translation of the nanoparticles in the range 1.3 sup<=...

  13. The Transverse Asymmetry A{sub T}, from Quasi-elastic {sup 3}{ovr He}({rvec e}, e{prime}) Process and the Neutron Magnetic Form Factor

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xu; Dipangkar Dutta; Feng Xiong; Brian Anderson; Leonard Auerbach; Todd Averett; William Bertozzi; Tim Black; John Calarco; Lawrence Cardman; Gordon Cates; Zhengwei Chai; Jian-ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; G.S. Corrado; C. Crawford; Daniel Dale; Alexandre Deur; Pibero Djawotho; Bradley Filippone; John Finn; Haiyan Gao; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Walter Gloeckle; J. Golak; Javier Gomez; Viktor Gorbenko; Jens-ole Hansen; F. Hersman; Douglas Higinbotham; Richard Holmes; Calvin Howell; Emlyn Hughes; Thomas Humensky; Sebastien Incerti; Cornelis De Jager; John Jensen; Xiaodong Jiang; C.E. Jones; Mark Jones; R. Kahl; H. Kamada; A. Kievsky; Ioannis Kominis; Wolfgang Korsch; Kevin Kramer; Gerfried Kumbartzki; Michael Kuss; Enkeleida Lakuriqi; Meihua Liang; Nilanga Liyanage; John Lerose; Sergey Malov; Demetrius Margaziotis; J.W. Martin; Kathy Mccormick; Robert Mckeown; Kevin Mcilhany; Zein-eddine Meziani; Robert Michaels; G.W. Miller; Joseph Mitchell; Sirish Nanda; E. Pace; Tina Pavlin; Gerassimos Petratos; Roman Pomatsalyuk; D. Pripstein; David Prout; Ronald Ransome; Yves Roblin; Marat Rvachev; Arunava Saha; G. Salme; Michael Schnee; Taeksu Shin; Karl Slifer; Paul Souder; Steffen Strauch; Riad Suleiman; Mark Sutter; Bryan Tipton; Luminita Todor; Michele Viviani; Branislav Vlahovic; J. Watson; Claude Williamson; H. Witala; Bogdan Wojtsekhowski; Jen-chuan Yeh; Piotr Zolnierczuk

    2000-10-01

    We have measured the transverse asymmetry from inclusive scattering of longitudinally polarized electrons from polarized {sup 3}He nuclei at quasi-elastic kinematics in Hall A at Jefferson Lab with high statistical and systematic precision. The neutron magnetic form factor was extracted based on Faddeev calculations with an experimental uncertainty of less than 2%.

  14. The Transverse Asymmetry $A_{T'}$ from Quasi-elastic $^{3}\\vec{He}(\\vec{e},e')$ Process and the Neutron Magnetic Form Factor

    CERN Document Server

    Xu, W; Xiong, F; Anderson, B; Auberbach, L; Averett, T; Bertozzi, W; Black, T; Calarco, J R; Cardman, L S; Cates, G D; Chai, Z W; Chen, J P; Choi, S; Chudakov, E A; Churchwell, S; Corrado, G S; Crawford, C; Dale, D; Deur, A; Djawotho, P; Filippone, B W; Finn, J M; Gao, H; Gilman, R; Glamazdin, A V; Glashausser, C; Glöckle, W; Golak, J; Gómez, J; Gorbenko, V G; Hansen, J O; Hersman, F W; Higinbotham, D W; Holmes, R; Howell, C R; Hughes, E; Humensky, B; Incerti, S; De Jager, C W; Jensen, J S; Jiang, X; Jones, C E; Jones, M; Kahl, R; Kamada, H; Kievsky, A; Kominis, I; Korsch, W; Krämer, K; Kumbartzki, G J; Kuss, M W; Lakuriqi, E; Liang, M; Liyanage, N K; Le Rose, J J; Malov, S Y; Margaziotis, D J; Martin, J W; McCormick, K; McKeown, R D; McIlhany, K; Meziani, Z E; Michaels, R; Miller, G W; Mitchell, J; Nanda, S; Pace, E; Pavlin, T; Petratos, G G; Pomatsalyuk, R I; Pripstein, D A; Prout, D L; Ransome, R D; Roblin, Y; Rvachev, M M; Saha, A; Salmè, G; Schnee, M; Shin, T; Slifer, K J; Souder, P A; Strauch, S; Suleiman, R; Sutter, M F; Tipton, B; Todor, L; Viviani, M; Vlahovic, B; Watson, J; Williamson, C F; Witala, H; Wojtsekhowski, B B; Yeh, J

    2000-01-01

    We have measured the transverse asymmetry from inclusive scattering of longitudinally polarized electrons from polarized 3He nuclei at quasi-elastic kinematics in Hall A at Jefferson Lab with high statistical and systematic precision. The neutron magnetic form factor was extracted based on Faddeev calculations with an experimental uncertainty of less than 2 %.

  15. Simulating moist convection with a quasi-elastic sigma coordinate model

    CSIR Research Space (South Africa)

    Bopape, Mary-Jane M

    2012-09-01

    Full Text Available possibly occurs because of a stronger downdraft in the simulations with ice which acts as a trigger for new cell development. In all the simulations, ice never reached the ground, it melted and evaporated and therefore cooled the air more than a... approach divides the particle distribution into 20 or more finite sizes and categories. This division of particle distribution into numerous bins requires much larger memory and computational capabilities, and poor knowledge of ice phase physics...

  16. Using Quasi-Elastic Events to Measure Neutrino Oscillations with MINOS Detectors in the NuMI Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Watabe, Masaki [Texas A & M Univ., College Station, TX (United States)

    2010-05-01

    MINOS (Main Injector Neutrino Oscillation Search) experiment has been designed to search for a change in the avor composition of a beam of muon neutrinos as they travel between the Near Detector at Fermi National Accelerator Laboratory and the Far Detector in the Soudan mine in Minnesota, 735 km from the target. The MINOS oscillation analysis is mainly performed with the charged current (CC) events and sensitive to constrain high- Δm2 values. However, the quasi-elastic (QEL) charged current interaction is dominant in the energy region important to access low- m2 values. For further improvement, the QEL oscillation analysis is performed in this dissertation. A data sample based on a total of 2.50 x 1020 POT is used for this analysis. In summary, 55 QEL-like events are observed at the Far detector while 87.06 ± 13.17 (syst:) events are expected with null oscillation hypothesis. These data are consistent with disappearance via oscillation with m2 = 2:10 0.37 (stat:) ± 0.24 (syst:) eV2 and the maximal mixing angle.

  17. Quasi-elastic neutron scattering study on water and polymer dynamics in thermo/pressure sensitive polymer solutions.

    Science.gov (United States)

    Osaka, Noboru; Shibayama, Mitsuhiro; Kikuchi, Tatsuya; Yamamuro, Osamu

    2009-10-01

    Dynamics of water and poly(N-isopropylacrylamide) (PNIPA) in concentrated aqueous solutions, where the majority of water molecules are attached to polymer chains, has been investigated with use of incoherent quasi-elastic neutron scattering (QENS) and dynamic light scattering (DLS) measurements as functions of temperature, T, and hydrostatic pressure, P. It was observed by QENS that the self-diffusion coefficient, D(water), of water in PNIPA/H(2)O solutions increased by P at temperatures below the lower critical solution temperature (LCST) of PNIPA aqueous solutions. However, above the LCST, D(water) decreased by P, as is often reported in non-hydrogen bonding solutions. In isobaric heating runs, therefore, the jump in D(water) at LCST decreased with increasing pressure. On the other hand, the mean-square displacement, , of the local vibrational motion of PNIPA in PNIPA/D(2)O solutions, where the incoherent scattering signal of PNIPA was predominantly observed, was reduced due to the aggregation behavior of PNIPA by pressurizing, which was also confirmed by using DLS. The jump in at the LCST became gradual by pressurizing, which was consistent with the changes of the dynamics of water obtained in PNIPA/H(2)O solutions.

  18. Measurement of the Antineutrino Double-Differential Charged-Current Quasi-Elastic Scattering Cross Section at MINERvA

    Energy Technology Data Exchange (ETDEWEB)

    Patrick, Cheryl [Northwestern U.

    2016-01-01

    Next-generation neutrino oscillation experiments, such as DUNE and Hyper-Kamiokande, hope to measure charge-parity (CP) violation in the lepton sector. In order to do this, they must dramatically reduce their current levels of uncertainty, particularly those due to neutrino-nucleus interaction models. As CP violation is a measure of the difference between the oscillation properties of neutrinos and antineutrinos, data about how the less-studied antineutrinos interact is especially valuable. We present the MINERvA experiment's first double-differential scattering cross sections for antineutrinos on scintillator, in the few-GeV range relevant to experiments such as DUNE and NOvA. We also present total antineutrino-scintillator quasi-elastic cross sections as a function of energy, which we compare to measurements from previous experiments. As well as being useful to help reduce oscillation experiments' uncertainty, our data can also be used to study the prevalence of various cor relation and final-state interaction effects within the nucleus. We compare to models produced by different model generators, and are able to draw first conclusions about the predictions of these models.

  19. Theory of quasi-elastic secondary emission from a quantum dot in the regime of vibrational resonance.

    Science.gov (United States)

    Rukhlenko, Ivan D; Fedorov, Anatoly V; Baymuratov, Anvar S; Premaratne, Malin

    2011-08-01

    We develop a low-temperature theory of quasi-elastic secondary emission from a semiconductor quantum dot, the electronic subsystem of which is resonant with the confined longitudinal-optical (LO) phonon modes. Our theory employs a generalized model for renormalization of the quantum dot's energy spectrum, which is induced by the polar electron-phonon interaction. The model takes into account the degeneration of electronic states and allows for several LO-phonon modes to be involved in the vibrational resonance. We give solutions to three fundamental problems of energy-spectrum renormalization--arising if one, two, or three LO-phonon modes resonantly couple a pair of electronic states--and discuss the most general problem of this kind that admits an analytical solution. With these results, we solve the generalized master equation for the reduced density matrix, in order to derive an expression for the differential cross section of secondary emission from a single quantum dot. The obtained expression is then analyzed to establish the basics of optical spectroscopy for measuring fundamental parameters of the quantum dot's polaron-like states.

  20. Diffusive properties of water in Artemia cysts as determined from quasi-elastic neutron scattering spectra. [Artemia shrimp

    Energy Technology Data Exchange (ETDEWEB)

    Trantham, E.C.; Rorschach, H.E.; Clegg, J.S.; Hazlewood, C.F.; Nicklow, R.M.; Wakabayashi, N.

    1984-05-01

    Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, 20% agarose gel (hydration four grams H/sub 2/O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H/sub 2/O per gram of dry solids. The spectra were interpreted using a two-component model that included contributions from the covalently bonded protons and the hydration water, and a mobile water fraction. The mobile fraction was described by a jump-diffusion correlation function for the translation motion and a simple diffusive orientational correlation function. The results for the line widths ..gamma..(Q/sup 2/) for pure water were in good agreement with previous measurements. The agarose results were consistent with NMR measurements that show a slightly reduced translational diffusion for the mobile water fraction. The Artemia results show that the translational diffusion coefficient of the mobile water fraction was greatly reduced from that of pure water. The line width was determined mainly by the rotational motion, which was also substantially reduced from the pure water value as determined from dielectric relaxation studies. The translational and rotational diffusion parameters were consistent with the NMR measurements of diffusion and relaxation. Values for the hydration fraction and the mean square thermal displacement as determined from the Q-dependence of line areas were also obtained.

  1. Derivation of capture and reaction cross sections from experimental quasi-elastic and elastic backscattering probabilities

    CERN Document Server

    Sargsyan, V V; Antonenko, N V; Gomes, P R S

    2013-01-01

    The direct measurement of the reaction or capture (fusion) cross section is a difficult task since it would require the measurement of individual cross sections of many reaction channels, and most of them could be reached only by specific experiments. This would require different experimental set-ups not always available at the same laboratory and, consequently, such direct measurements would demand a large amount of beam time and would take probably some years to be reached. Because of that, the measurements of elastic scattering angular distributions that cover full angular ranges and optical model analysis have been used for the determination of reaction cross sections. This traditional method consists in deriving the parameters of the complex optical potentials which fit the experimental elastic scattering angular distributions and then of deriving the reaction cross sections predicted by these potentials. Even so, both the experimental part and the analysis of this latter method are not so simple. In the...

  2. Quasi-elastic reactions: an interplay of reaction dynamics and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Szilner, S; Jelavic-Malenica, D; Mijatovic, T; Soic, N [Ruder Botkovic Institute and University of Zagreb, Zagreb (Croatia); Corradi, L; Fioretto, E; Gadea, A; Mengoni, D; Stefanini, A M; Valiente-Dobon, J J [INFN - Laboratori Nazionali di Legnaro, Legnaro (Italy); Pollarolo, G [INFN and Universita di Torino (Italy); Beghini, S; Farnea, E; Lunardi, S; Montagnoli, G; Scarlassara, F; Ur, C A [INFN and Universita di Padova, Padova (Italy); Courtin, S; Haas, F; Lebhertz, D, E-mail: szilner@irb.hr [IPHC, CNRS/IN2P3 and Universite de Strasbourg, Strasbourg (France)

    2011-02-01

    The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers based on trajectory reconstruction that reached an unprecedented efficiency and selectivity. The coupling of these spectrometers with large {gamma} arrays allowed the identification of individual excited states, their population pattern and decay modes via particle-{gamma} coincidences. In the present paper aspects of fragment-{gamma} coincidence studies measured with the Prisma-Clara set up in {sup 40}Ca+{sup 96}Zr and {sup 40}Ar+{sup 208}Pb are discussed. In particular, we report about states of particle-phonon character, supporting the idea that the relevant degrees of freedom acting in the reaction dynamics define the final yield distributions.

  3. Dynamics of iodine anions in KI and LiI aqueous solutions studied by 127I nuclear resonant quasi-elastic scattering

    Science.gov (United States)

    Haruki, Rie; Koshimizu, Masanori; Nishikido, Fumihiko; Masuda, Ryo; Kobayashi, Yasuhiro; Seto, Makoto; Yoda, Yoshitaka; Kishimoto, Shunji

    2016-12-01

    The dynamics of iodine ions in potassium iodide (KI) and lithium iodide (LiI) aqueous solutions have been studied through 127I nuclear resonant quasi-elastic scattering (NRQES). A newly developed Si (12 2 2) double crystal monochromator for 127I 57.6 keV excitation is used. Broadening due to a diffusive motion is measured in the energy spectra of the NRQES from the solutions.

  4. Translational and rotational dynamics of water contained in aged Portland cement pastes studied by quasi-elastic neutron scattering.

    Science.gov (United States)

    Li, Hua; Zhang, Li-Li; Yi, Zhou; Fratini, Emiliano; Baglioni, Piero; Chen, Sow-Hsin

    2015-08-15

    Cement is a widely used construction material in the world. The quality and durability of aged cement pastes have a strong relationship with the water contained in it. The translational and rotational dynamics of water in ordinary Portland cement (OPC) pastes cured for 7, 14 and 30days were studied by analyzing Quasi-elastic Neutron Scattering (QENS) data. The effect of a new super-plasticizer (SP) additive was also studied by comparing the samples with and without the additive. By fitting the QENS spectra with the Jump-diffusion and Rotation-diffusion Model (JRM), six important parameters including the bound water index (BWI), the self-diffusion coefficient, D(t), the average residence time, τ0, the rotational diffusion constant, D(r), the rotational residence time, τ(r), and the mean squared displacement (MSD), 〈u(2)〉, were obtained. From these parameters, we can quantitatively follow the evolution of the bound water fraction (BWI). We can clearly see the different time ranges for the translational and rotational dynamics of water contained in the OPC pastes by τ0 and τ(r). From the MSD values compared with those of molecular dynamics simulation, we can distinguish between immobile water (mainly bound water) and mobile water, which includes confined water and ultraconfined water. Furthermore, by the fitted parameters' values and their change of slopes with increasing setting time for cement pastes with and without additive SP, it becomes clear that the effect of additive SP is to make the mobile water more confined and induce a more uniform the aging process during the evolution of the OPC pastes.

  5. Solvent Dynamics in Solutions of PNIPAM in Water/Methanol Mixtures-A Quasi-Elastic Neutron Scattering Study.

    Science.gov (United States)

    Kyriakos, Konstantinos; Philipp, Martine; Silvi, Luca; Lohstroh, Wiebke; Petry, Winfried; Müller-Buschbaum, Peter; Papadakis, Christine M

    2016-05-26

    The solvent dynamics of concentrated solutions of poly(N-isopropylacrylamide) (PNIPAM, 25 wt %) in water/methanol mixtures (85:15 v/v) are measured with the aim of shedding light onto the cononsolvency effect. Quasi-elastic neutron scattering (QENS) with contrast variation has been carried out at temperatures below and above the cloud point by using in the first set of experiments the mixture H2O:d-MeOD (d-MeOD denotes fully deuterated methanol) as a solvent and in the second set of experiments the mixture D2O:MeOH (MeOH denotes methanol). As a reference, bulk H2O, bulk MeOH and the mixtures H2O:d-MeOD and D2O:MeOH (both 85:15 v/v) have been investigated as well. In the PNIPAM solution in H2O:d-MeOD, two water populations are identified, namely strongly and less strongly arrested water. At the cloud point, the former is partially released from PNIPAM. The diffusion coefficient of the latter one is similar to the one in the water/methanol mixture, and its residence time decreases at the cloud point. The PNIPAM solution in D2O:MeOH reveals similar dynamics to the one in H2O:d-MeOD which may reflect that the dynamics of MeOH near the PNIPAM chain is similar to the one of H2O. The similarity may, however, partially be due to H/D exchange between D2O and MeOH. In both PNIPAM solutions, the mean-square displacement of the PNIPAM chain decreases gradually above the cloud point.

  6. Insights into nuclear reactions through fusion barrier distribution measurements

    CERN Document Server

    Hinde, D J; Morton, C R; Berriman, A C; Butt, R D; Newton, J O

    1999-01-01

    The study of nuclear fusion has been greatly enhanced following the realisation that an experimental fusion barrier distribution can be determined from precisely measured fusion cross-sections. Experimental fusion barrier distributions for different reactions have shown clear signatures of a range of nuclear structure effects, for example those of static quadrupole and hexadecapole deformations, and of coupling to single- and double-phonon states. Applications of this improved quantitative understanding of fusion in the fields of fission, and fusion of weakly bound nuclei are discussed.

  7. Measurement of the Charged-Current Quasi-Elastic Cross-Section for Electron Neutrinos on a Hydrocarbon Target

    Energy Technology Data Exchange (ETDEWEB)

    Wolcott, Jeremy [Univ. of Rochester, NY (United States)

    2016-01-01

    Appearance-type neutrino oscillation experiments, which observe the transition from muon neutrinos to electron neutrinos, promise to help answer some of the fundamental questions surrounding physics in the post-Standard-Model era. Because they wish to observe the interactions of electron neutrinos in their detectors, and because the power of current results is typically limited by their systematic uncertainties, these experiments require precise estimates of the cross-section for electron neutrino interactions. Of particular interest is the charged-current quasi-elastic (CCQE) process, which gures signi cantly in the composition of the reactions observed at the far detector. However, no experimental measurements of this crosssection currently exist for electron neutrinos; instead, current experiments typically work from the abundance of muon neutrino CCQE cross-section data and apply corrections from theoretical arguments to obtain a prediction for electron neutrinos. Veri cation of these predictions is challenging due to the di culty of constructing an electron neutrino beam, but the advent of modern high-intensity muon neutrino beams|together with the percent-level electron neutrino impurity inherent in these beams| nally presents the opportunity to make such a measurement. We report herein the rst-ever measurement of a cross-section for an exclusive state in electron neutrino scattering, which was made using the MINER A detector in the NuMI neutrino beam at Fermilab. We present the electron neutrino CCQE di erential cross-sections, which are averaged over neutrinos of energies 1-10 GeV (with mean energy of about 3 GeV), in terms of various kinematic variables: nal-state electron angle, nal-state electron energy, and the square of the fourmomentum transferred to the nucleus by the neutrino , Q2. We also provide a total cross-section vs. neutrino energy. While our measurement of this process is found to be in agreement with the predictions of the GENIE

  8. Distributions of methyl group rotational barriers in polycrystalline organic solids

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, Peter A., E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Conn, Kathleen G. [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Division of Education and Human Services, Neumann University, One Neumann Drive, Aston, Pennsylvania 19014-1298 (United States); Mallory, Clelia W. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Rheingold, Arnold L. [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0358 (United States); Rotkina, Lolita [Regional Nanotechnology Facility, Laboratory for Research on the Structure of Matter, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104-6202 (United States); Wang, Xianlong, E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China)

    2013-11-28

    We bring together solid state {sup 1}H spin-lattice relaxation rate measurements, scanning electron microscopy, single crystal X-ray diffraction, and electronic structure calculations for two methyl substituted organic compounds to investigate methyl group (CH{sub 3}) rotational dynamics in the solid state. Methyl group rotational barrier heights are computed using electronic structure calculations, both in isolated molecules and in molecular clusters mimicking a perfect single crystal environment. The calculations are performed on suitable clusters built from the X-ray diffraction studies. These calculations allow for an estimate of the intramolecular and the intermolecular contributions to the barrier heights. The {sup 1}H relaxation measurements, on the other hand, are performed with polycrystalline samples which have been investigated with scanning electron microscopy. The {sup 1}H relaxation measurements are best fitted with a distribution of activation energies for methyl group rotation and we propose, based on the scanning electron microscopy images, that this distribution arises from molecules near crystallite surfaces or near other crystal imperfections (vacancies, dislocations, etc.). An activation energy characterizing this distribution is compared with a barrier height determined from the electronic structure calculations and a consistent model for methyl group rotation is developed. The compounds are 1,6-dimethylphenanthrene and 1,8-dimethylphenanthrene and the methyl group barriers being discussed and compared are in the 2–12 kJ mol{sup −1} range.

  9. Monoclinic zirconia distributions in plasma-sprayed thermal barrier coatings

    Science.gov (United States)

    Lance, M. J.; Haynes, J. A.; Ferber, M. K.; Cannon, W. R.

    2000-03-01

    Phase composition in an air plasma-sprayed Y2O3-stabilized ZrO2 (YSZ) top coating of a thermal barrier coating (TBC) system was characterized. Both the bulk phase content and localized pockets of monoclinic zirconia were measured with Raman spectroscopy. The starting powder consisted of ˜15 vol.% monoclinic zirconia, which decreased to ˜2 vol.% in the as-sprayed coating. Monoclinic zirconia was concentrated in porous pockets that were evenly distributed throughout the TBC. The pockets resulted from the presence of unmelted granules in the starting powder. The potential effect of the distributed monoclinic pockets on TBC performance is discussed.

  10. Total, inelastic and (quasi-)elastic cross sections of high energy pA and gamma-A reactions with the dipole formalism

    CERN Document Server

    Gustafson, Gosta; Ster, Andras; Corgo, Tamas

    2015-01-01

    In order to understand the initial partonic state in proton-nucleus and electron-nucleus collisions, we investigate the total, inelastic, and (quasi-)elastic cross sections in pA and gamma-A collisions, as these observables are insensitive to possible collective effects in the final state interactions. We used as a tool the DIPSY dipole model, which is based on BFKL dynamics including non-leading effects, saturation, and colour interference, which we have extended to describe collisions of protons and virtual photons with nuclei. We present results for collisions with O, Cu, and Pb nuclei, and reproduce preliminary data on the pPb inelastic cross section at LHC by CMS and LHCb. The large NN cross section results in pA scattering that scales approximately with the area. The results are compared with conventional Glauber model calculations, and we note that the more subtle dynamical effects are more easily studied in the ratios between the total, inelastic and (quasi-)elastic cross sections. The smaller photon ...

  11. Measurement of double-polarization asymmetries in the quasi-elastic $^3\\vec{\\mathrm{He}}(\\vec{\\mathrm{e}},\\mathrm{e}'\\mathrm{d})$ process

    CERN Document Server

    Mihovilovič, M; Long, E; Zhang, Y -W; Allada, K; Anderson, B; Annand, J R M; Averett, T; Boeglin, W; Bradshaw, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J P; Chudakov, E; De Leo, R; Deng, X; Deltuva, A; Deur, A; Dutta, C; Fassi, L El; Flay, D; Frullani, S; Garibaldi, F; Gao, H; Gilad, S; Gilman, R; Glamazdin, O; Golak, J; Golge, S; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, J; Ibrahim, H; de Jager, C W; Jensen, E; Jiang, X; Jones, M; Kang, H; Katich, J; Khanal, H P; Kievsky, A; King, P; Korsch, W; LeRose, J; Lindgren, R; Lu, H -J; Luo, W; Marcucci, L; Markowitz, P; Meziane, M; Michaels, R; Moffit, B; Monaghan, P; Muangma, N; Nanda, S; Norum, B E; Pan, K; Parno, D; Piasetzky, E; Posik, M; Punjabi, V; Puckett, A J R; Qian, X; Qiang, Y; Qui, X; Riordan, S; Saha, A; Sauer, P U; Sawatzky, B; Schiavilla, R; Shabestari, M; Shahinyan, A; Shoenrock, B; Širca, S; Skibiński, R; John, J St; Subedi, R; Sulkosky, V; Tobias, W A; Tireman, W; Urciuoli, G M; Viviani, M; Wang, D; Wang, K; Wang, Y; Watson, J; Wojtsekhowski, B; Witała, H; Ye, Z; Zhan, X; Zhang, Y; Zheng, X; Zhao, B; Zhu, L

    2014-01-01

    We present a precise measurement of double-polarization asymmetries in the $^3\\vec{\\mathrm{He}}(\\vec{\\mathrm{e}},\\mathrm{e}'\\mathrm{d})$ reaction. This particular process is a uniquely sensitive probe of hadron dynamics in $^3\\mathrm{He}$ and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasi-elastic kinematics at $Q^2 = 0.25\\,(\\mathrm{GeV}/c)^2$ for missing momenta up to $270\\,\\mathrm{MeV}/c$. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on $p_\\mathrm{m}$ and $\\omega$, but are systematically offset. Beyond the region of the quasi-elastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two- and/or three-body dynamics is required.

  12. A new apparatus design for high temperature (up to 950 °C) quasi-elastic neutron scattering in a controlled gaseous environment

    Energy Technology Data Exchange (ETDEWEB)

    Al-Wahish, Amal [Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); Armitage, D.; Hill, B.; Mills, R.; Santodonato, L.; Herwig, K. W. [Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37861-6475 (United States); Al-Binni, U. [Department of Physics, Astronomy and Geology, Berry College, Mount Berry, Georgia 30149 (United States); Jalarvo, N. [Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS), Outstation at Spallation Neutron Source (SNS), and Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473 (United States); Mandrus, D. [Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6100 (United States)

    2015-09-15

    A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.

  13. Measurement of the $M_A^{QE}$ parameter using multiple quasi-elastic dominated sub-samples in the minos near detector

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Nathan Samuel [Indiana Univ., Bloomington, IN (United States)

    2011-12-05

    The Main Injector Neutrino Oscillation Search (MINOS) is a two detector, long baseline neutrino oscillation experiment. The MINOS near detector is an ironscintillator tracking/sampling calorimeter and has recorded the world’s largest data set of neutrino interactions in the 0-5 GeV region. This high statistics data set is used to make precision measurements of neutrino interaction cross-sections on iron. The Q2 dependence in charged current quasi-elastic (CCQE) scattering probes the axial and vector structure (form factor) of the nucleon/nuclear target, and nuclear effects in neutrino scattering. Presented here is a study of the MINOS Data that will introduce a method that improves the existing MINOS CCQE analysis. This analysis uses an additional CCQE dominated sub-sample from a different kinematic region to reduce correlations between fit parameters in the existing MINOS CCQE analysis. The measured value of the axial-vector mass is MQE A = 1.312+0.037 -0.038(fit)+0.123 -0.265(syst.) GeV.

  14. Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction $^3$He$^\\uparrow(e,e^\\prime)$

    CERN Document Server

    Zhang, Y -W; Mihovilovič, M; Jin, G; Allada, K; Anderson, B; Annand, J R M; Averett, T; Boeglin, W; Bradshaw, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J P; Chudakov, E; De Leo, R; Deng, X; Deur, A; Dutta, C; Fassi, L El; Flay, D; Frullani, S; Garibaldi, F; Gao, H; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, J; Ibrahim, H; de Jager, C W; Jensen, E; Jiang, X; John, J St; Jones, M; Kang, H; Katich, J; Khanal, H P; King, P; Korsch, W; LeRose, J; Lindgren, R; Lu, H -J; Luo, W; Markowitz, P; Meziane, M; Michaels, R; Moffit, B; Monaghan, P; Muangma, N; Nanda, S; Norum, B E; Pan, K; Parno, D; Piasetzky, E; Posik, M; Punjabi, V; Puckett, A J R; Qian, X; Qiang, Y; Qiu, X; Riordan, S; Ron, G; Saha, A; Sawatzky, B; Schiavilla, R; Schoenrock, B; Shabestari, M; Shahinyan, A; Širca, S; Subedi, R; Sulkosky, V; Tobias, W A; Tireman, W; Urciuoli, G M; Wang, D; Wang, K; Wang, Y; Watson, J; Wojtsekhowski, B; Ye, Y; Ye, Z; Zhan, X; Zhang, Y; Zheng, X; Zhao, B; Zhu, L

    2015-01-01

    We report the first measurement of the target single-spin asymmetry, $A_y$, in quasi-elastic scattering from the inclusive reaction $^3$He$^{\\uparrow}(e,e^\\prime)$ on a $^3$He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero $A_y$ can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at $Q^{2}=$ 0.13, 0.46 and 0.97 GeV$^{2}$. These measurements demonstrate, for the first time, that the $^3$He asymmetry is clearly non-zero and negative with a statistical significance of (8-10)$\\sigma$. Using measured proton-to-$^{3}$He cross-section ratios and the effective polarization approximation, neutron asymmetries of $-$(1-3)% were obtained. The neutron asymmetry at high $Q^2$ is related to moments of the Gene...

  15. Force field based molecular dynamics simulations in highly conducting compounds of poly(aniline). A comparison with quasi-elastic neutron scattering measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sniechowski, M. [Laboratoire de Spectrometrie Physique, UMR5588 (CNRS-UJF), Universite J. Fourier, Grenoble I, Domaine Universitaire, B.P. 87, 38402 St. Martin d' Heres, Cedex (France); Faculty of Physics and Nuclear Techniques, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Djurado, D. [Laboratoire de Physique des Metaux Synthetiques, CEA Grenoble, DRFMC/SI3M/SPrAM, UMR 5819 (CEA/CNRS/UJF), 17 Rue des Martyrs, 38054 Grenoble, Cedex 9 (France)], E-mail: djurado@drfmc.ceng.cea.fr; Bee, M. [Laboratoire de Spectrometrie Physique, UMR5588 (CNRS-UJF), Universite J. Fourier, Grenoble I, Domaine Universitaire, B.P. 87, 38402 St. Martin d' Heres, Cedex (France); Institut Laue Langevin, 6 rue Jules Horovitz, B.P. 156, 38042 Grenoble, Cedex 9 (France); Gonzalez, M.A. [Institut Laue Langevin, 6 rue Jules Horovitz, B.P. 156, 38042 Grenoble, Cedex 9 (France); Johnson, M.R. [Institut Laue Langevin, 6 rue Jules Horovitz, B.P. 156, 38042 Grenoble, Cedex 9 (France); Rannou, P. [Laboratoire de Physique des Metaux Synthetiques, CEA Grenoble, DRFMC/SI3M/SPrAM, UMR 5819 (CEA/CNRS/UJF), 17 Rue des Martyrs, 38054 Grenoble, Cedex 9 (France); Dufour, B. [Laboratoire de Physique des Metaux Synthetiques, CEA Grenoble, DRFMC/SI3M/SPrAM, UMR 5819 (CEA/CNRS/UJF), 17 Rue des Martyrs, 38054 Grenoble, Cedex 9 (France); Luzny, W. [Faculty of Physics and Nuclear Techniques, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland)

    2005-10-31

    Dynamics of counter-ions in poly(aniline) doped with di-(2-butoxyethoxyethyl)ester of 4-sulfophthalic acid have been simulated using force field based molecular dynamics involving a semi-empirical charge equilibration procedure and charge rescaling based on DFT calculations. Due to particular relaxational and structural characteristics of such 'plastdoped' poly(anilines), these simulations have proved to be a very effective tool for reproducing the main structural and dynamic features of the material. The experiment/simulation comparison for dynamics is very good in the 10{sup -10}-10{sup -13} s time range. In particular, mean square displacements extracted from the molecular dynamics simulations for atoms in the counter-ions are in good agreement with the analytical model used to analyse the quasi-elastic neutron scattering data. The use of a larger simulation box and longer simulation time give good agreement in the extended time domain and reveal a dynamical heterogeneity between the counter-ions that was not foreseen in the analytical model.

  16. Heavy ion reactions around the Coulomb barrier

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O+208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface re gion. The breakup cross section and the coupling between breakup and elastic scattering are small.

  17. Hydrogen motions and the -relaxation in glass-forming polymers: Molecular dynamics simulation and quasi-elastic neutron scattering results

    Indian Academy of Sciences (India)

    J Colmenero; A Arbe; F Alvarez; A Narros; D Richter; M Monkenbush; B Farago

    2004-07-01

    The combination of molecular dynamics simulations and neutron scattering measurements on three different glass-forming polymers (polyisoprene, poly(vinyl ethylene) and polybutadiene) has allowed to establish the existence of a crossover from Gaussian to non-Gaussian behavior for the incoherent scattering function in the -relaxation regime. The deviation from Gaussian behavior observed can be reproduced assuming the existence of a distribution of discrete jump lengths underlying the sublinear diffusion of the atomic motions during the structural relaxation.

  18. Study of the (e,e'p) quasi-elastic reaction in complex nuclei: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, Joaquin Lopez [Complutense Univ. of Madrid (Spain)

    2010-03-01

    Experimental coincidence cross section and transverse-longitudinal asymmetry ATL have been obtained for the quasielastic (e,e'p) reaction in 16O, 12C, and {sup 208}Pb in constant q-ω kinematics in the missing momentum range -350 < pmiss < 350 MeV/c. In these experiments, performed in experimental Hall A of the Thomas Jefferson National Accelerator Facility (JLAB), the beam energy and the momentum and angle of the scattered electrons were kept fixed, while the angle between the proton momentum and the momentum transfer q was varied in order to map out the missing momentum distribution. The experimental cross section and ATL asymmetry have been compared with Monte Carlo simulations based on Distorted Wave Impulse Approximation (DWIA) calculations with both relativistic and non-relativistic spinor structure. The spectroscopic factors obtained for both models are in agreement with previous experimental values, while ATL measurements favor the relativistic DWIA calculation. This thesis describes the details of the experimental setup, the calibration of the spectrometers, the techniques used in the data analysis to derive the final cross sections and the ATL, the ingredients of the theoretical calculations employed and the comparison of the results with the simulations based on these theoretical models.

  19. Simulation of energy barrier distributions using real particle parameters and comparison with experimental obtained results

    Energy Technology Data Exchange (ETDEWEB)

    Büttner, M., E-mail: Markus.Buettner@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena (Germany); Schiffler, M. [Institut für Geowissenschaften, Friedrich-Schiller-Universität Jena, Burgweg 11, 07749 Jena (Germany); Weber, P.; Seidel, P. [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena (Germany)

    2013-11-15

    Distributions of energy barriers in systems of magnetic nanoparticles have been calculated by means of the path integral method and the results have been compared with distributions previously obtained in our experiments by means of the temperature dependent magnetorelaxation method. The path integral method allowed to obtain energies of the interactions of magnetic moments of nanoparticles with axes of their easy magnetisation as well as energies of mutual interactions of magnetic moments. Calculated distributions of energy barriers have been described satisfactorily by curves of the lognormal distribution. We found an agreement between the theory and the experiment at temperatures above approximately 100 K. The influence of the volume concentration of nanoparticles and agglomeration on the energy barrier distribution has been investigated. - Highlights: • The path integral method of calculation allows to satisfactorily reproduce the quantitative experimental results. • The simulations of the energy barrier distributions reflect the lognormal distribution of the MNP found in real experiments. • Higher particle volume concentration leads to a broadening of the simulated energy barrier distribution. • At low particle concentration there is only anisotropy energy. • In case of agglomeration the energy barrier distribution broadens.

  20. Breaking through: The effects of a velocity distribution on barriers to dust growth

    CERN Document Server

    Windmark, Fredrik; Ormel, Chris; Dullemond, Cornelis P

    2012-01-01

    It is unknown how far dust growth can proceed by coagulation. Obstacles to collisional growth are the fragmentation and bouncing barriers. However, in all previous simulations of the dust-size evolution in protoplanetary disks, only the mean collision velocity has been considered, neglecting that a small but possibly important fraction of the collisions will occur at both much lower and higher velocities. We study the effect of the probability distribution of impact velocities on the collisional dust growth barriers. Assuming a Maxwellian velocity distribution for colliding particles to determine the fraction of sticking, bouncing, and fragmentation, we implement this in a dust-size evolution code. We also calculate the probability of growing through the barriers and the growth timescale in these regimes. We find that the collisional growth barriers are not as sharp as previously thought. With the existence of low-velocity collisions, a small fraction of the particles manage to grow to masses orders of magnit...

  1. The role of ceramide chain length distribution on the barrier properties of the skin lipid membranes.

    Science.gov (United States)

    Mojumdar, E H; Kariman, Z; van Kerckhove, L; Gooris, G S; Bouwstra, J A

    2014-10-01

    The skin barrier function is provided by the stratum corneum (SC). The lipids in the SC are composed of three lipid classes: ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) which form two crystalline lamellar structures. In the present study, we investigate the effect of CER chain length distribution on the barrier properties of model lipid membranes mimicking the lipid composition and organization of SC. The membranes were prepared with either isolated pig CERs (PCERs) or synthetic CERs. While PCERs have a wide chain length distribution, the synthetic CERs are quite uniform in chain length. The barrier properties were examined by means of permeation studies using hydrocortisone as a model drug. Our studies revealed a reduced barrier in lipid membranes prepared with PCERs compared to synthetic CERs. Additional studies revealed that a wider chain length distribution of PCERs results in an enhanced hexagonal packing and increased conformational disordering of the lipid tails compared to synthetic CERs, while the lamellar phases did not change. This demonstrates that the chain length distribution affects the lipid barrier by reducing the lipid ordering and density within the lipid lamellae. In subsequent studies, the effect of increased levels of FFAs or CERs with a long acyl chain in the PCERs membranes was also studied. These changes in lipid composition enhanced the level of orthorhombic packing, reduced the conformational disordering and increased the barrier of the lipid membranes. In conclusion, the CER chain length distribution is an important key factor for maintaining a proper barrier. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Consistent energy barrier distributions in magnetic particle chains

    Energy Technology Data Exchange (ETDEWEB)

    Laslett, O., E-mail: O.Laslett@soton.ac.uk [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom); Ruta, S.; Chantrell, R.W. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Barker, J. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Friedman, G. [Electrical and Computer Engineering Department, Drexel University, Philadelphia, PA 19104 (United States); Hovorka, O. [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom)

    2016-04-01

    We investigate long-time thermal activation behaviour in magnetic particle chains of variable length. Chains are modelled as Stoner–Wohlfarth particles coupled by dipolar interactions. Thermal activation is described as a hopping process over a multidimensional energy landscape using the discrete orientation model limit of the Landau–Lifshitz–Gilbert dynamics. The underlying master equation is solved by diagonalising the associated transition matrix, which allows the evaluation of distributions of time scales of intrinsic thermal activation modes and their energy representation. It is shown that as a result of the interaction dependence of these distributions, increasing the particle chain length can lead to acceleration or deceleration of the overall relaxation process depending on the initialisation procedure.

  3. Effect of intergranular interactions on thermal energy barrier distribution in perpendicular media

    Science.gov (United States)

    Zhou, Hong; Bertram, H. Neal; Schabes, Manfred E.

    2002-05-01

    Micromagnetic simulations have been performed to simulate dynamic hysteresis loops in perpendicular media. Thermal energy barrier distributions have been calculated. For a fixed percentage of magnetization switched, a linear variation between the scaled applied field Ha(t)/HK and ln(f0t)1/2 is found. Without including intergranular magnetostatic interactions, intergranular exchange coupling reduces the thermal energy barrier distribution width, compared to the physical volume distribution width. However, the magnetostatic interactions increase the energy barrier width substantially. The increase is significantly reduced at smaller magnetostatic interactions. For the effective volume of 50% magnetization switched (V50), the results show V50=√ almost independent of intergranular magnetostatic and exchange interactions.

  4. Measurement of the Muon Neutrino Double-Differential Charged Current Quasi-Elastic Like Cross Section on a Hydrocarbon Target at Ev ~ 3.5 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Hurtado Anampa, Kenyi Paolo [Rio de Janeiro, CBPF

    2016-01-01

    The MINERvA Experiment (Main Injector Experiment v ₋ A interaction) [1] is a highly segmented detector of neutrinos, able to record events with high precision (over than thirteen million event in a four year run), using the NuMI Beam (Neutrino Main Injector) at the Fermi National Accelerator Laboratory [2]. This thesis presents a measurement of the Charged Current Quasi-Elastic Like1 vμ interaction on polystyrene scintillator (CH) in the MINERvA experiment with neutrino energies between 1.5 and 10 GeV. We use data taken between2 March 2010 and April 2012. The interactions were selected by requiring a negative muon, a reconstructed and identified proton, no michel electrons in the final state (in order to get rid of soft pions decaying) and a low calorimetric recoil energy away from the interaction vertex. The analysis is performed on 66,214 quasi-elastic like event candidates in the detectors tracker region with an estimated purity of 74%. The final measurement reported is a double differential cross sections in terms of the muon longitudinal and transversal momentum observables.

  5. Software Based Barriers To Integration Of Renewables To The Future Distribution Grid

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Emma; Kiliccote, Sila

    2014-06-01

    The future distribution grid has complex analysis needs, which may not be met with the existing processes and tools. In addition there is a growing number of measured and grid model data sources becoming available. For these sources to be useful they must be accurate, and interpreted correctly. Data accuracy is a key barrier to the growth of the future distribution grid. A key goal for California, and the United States, is increasing the renewable penetration on the distribution grid. To increase this penetration measured and modeled representations of generation must be accurate and validated, giving distribution planners and operators confidence in their performance. This study will review the current state of these software and modeling barriers and opportunities for the future distribution grid.

  6. Barrier effects on vertebrate distribution caused by a motorway crossing through fragmented forest landscape

    Directory of Open Access Journals (Sweden)

    Tellería, J. L.

    2011-12-01

    Full Text Available We analysed the effects of a 25–year–old motorway on the distribution of five vertebrates inhabiting a fragmented forest landscape and differing in their ability to move across linear infrastructures. We found clear evidence of barrier effects on the distribution of the forest lizard Psammodromus algirus. The roe deer (Capreolus capreolus was also unequally distributed on both sides of the motorway, but this could also be due, at least in part, to fragmentation. The eyed lizard (Timon lepidus, that can move through open fields, showed no evidence of barrier effects. The distribution of two small birds (Erithacus rubecula and Phylloscopus bonelli was unaffected by the motorway. Our results show that a motorway may severely restrict the distribution of species which can withstand high levels of forest fragmentation but show limited dispersal ability, highlighting the role of linear infrastructures in shaping species’ ranges at regional scales.

  7. Numerical investigation into effect of rear barrier pillar on stress distribution around a longwall face

    Institute of Scientific and Technical Information of China (English)

    鞠明和; 李学华; 姚强岭; 李冬伟; 种照辉; 周健

    2015-01-01

    Numerical investigation was performed to examine the effect of rear barrier pillar on stress distribution around a longwall face. Salamon theoretical formula was used to calculate the parameters of the caving zone, which was later assigned to double yield constitutive model in FLAC3D. Numerical results demonstrate that high stress concentration zone exists above the region where the second open-off cut intersects with the rear barrier pillar due to stress transfer and plastic zone expansion. It is also found that the maximum vertical stresses with varied distance to the seam floor are all within the projective plane of the rear barrier pillar and their positions concentrate on the barrier pillar adjacent to the connection corner of the second open-off cut. In addition, position of the maximum vertical stresses abruptly transfer from the connection corner adjacent to former panel to that adjacent to current panel along the panel direction.

  8. Transition path time distribution and the transition path free energy barrier.

    Science.gov (United States)

    Pollak, Eli

    2016-10-19

    The recent experimental measurement of the transition path time distributions of proteins presents several challenges to theory. Firstly, why do the fits of the experimental data to a theoretical expression lead to barrier heights which are much lower than the free energies of activation of the observed transitions? Secondly, there is the theoretical question of determining the transition path time distribution, without invoking the Smoluchowski limit. In this paper, we derive an exact expression for a transition path time distribution which is valid for arbitrary memory friction using the normal mode transformation which underlies Kramers' rate theory. We then recall that for low barriers, there is a noticeable difference between the transition path time distribution obtained with absorbing boundary conditions and free boundary conditions. For the former, the transition times are shorter, since recrossings of the boundaries are disallowed. As a result, if one uses the distribution based on absorbing boundary conditions to fit the experimental data, one will find that the transition path barrier will be larger than the values found based on a theory with free boundary conditions. We then introduce the paradigm of a transition path barrier height, and show that one should always expect it to be much smaller than the activation energy.

  9. Stress Distribution on Blasting Gallery Barrier Pillar due to Goaf Formation During Extraction

    Science.gov (United States)

    Kumar Reddy, Sandi; Sastry, Vedala Rama

    2016-10-01

    Semi-mechanised blasting gallery mining is a sustainable option to achieve higher production and productivity from underground thick coal seams. Judicious design of underground blasting gallery panel requires understanding of stress distribution on barrier pillars during different stages of extraction. This paper presents a study of stress distribution in and around barrier pillar for the different stages of extraction in the blasting gallery panel. Finite difference analysis taken up for final excavation (depillaring) in the panel with different stages of extraction. Analysis revealed that the stress transferred on barrier pillar increased as progress of excavation increased. Maximum stress was observed at a distance of 10 and 12 m from the pillar edge for virgin and goaved out panel sideby respectively, which gradually decreased towards centre of the pillar.

  10. Stress Distribution on Blasting Gallery Barrier Pillar due to Goaf Formation During Extraction

    Science.gov (United States)

    Kumar Reddy, Sandi; Sastry, Vedala Rama

    2015-09-01

    Semi-mechanised blasting gallery mining is a sustainable option to achieve higher production and productivity from underground thick coal seams. Judicious design of underground blasting gallery panel requires understanding of stress distribution on barrier pillars during different stages of extraction. This paper presents a study of stress distribution in and around barrier pillar for the different stages of extraction in the blasting gallery panel. Finite difference analysis taken up for final excavation (depillaring) in the panel with different stages of extraction. Analysis revealed that the stress transferred on barrier pillar increased as progress of excavation increased. Maximum stress was observed at a distance of 10 and 12 m from the pillar edge for virgin and goaved out panel sideby respectively, which gradually decreased towards centre of the pillar.

  11. Overcoming barriers to scheduling embedded generation to support distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    Wright, A.J.; Formby, J.R.

    2000-07-01

    Current scheduling of embedded generation for distribution in the UK is limited and patchy. Some DNOs actively schedule while others do none. The literature on the subject is mainly about accommodating volatile wind output, and optimising island systems, for both cost of supply and network stability. The forthcoming NETA will lower prices, expose unpredictable generation to imbalance markets and could introduce punitive constraint payments on DNOs, but at the same time create a dynamic market for both power and ancillary services from embedded generators. Most renewable generators either run as base load (e.g. waste ) or according to the vagaries of the weather (e.g. wind, hydro), so offer little scope for scheduling other than 'off'. CHP plant is normally heat- led for industrial processes or building needs, but supplementary firing or thermal storage often allow considerable scope for scheduling. Micro-CHP with thermal storage could provide short-term scheduling, but tends to be running anyway during the evening peak. Standby generation appears to be ideal for scheduling, but in practice operators may be unwilling to run parallel with the network, and noise and pollution problems may preclude frequent operation. Statistical analysis can be applied to calculate the reliability of several generators compared to one; with a large number of generators such as micro-CHP reliability of a proportion of load is close to unity. The type of communication for generation used will depend on requirements for bandwidth, cost, reliability and whether it is bundled with other services. With high levels of deeply embedded, small-scale generation using induction machines, voltage control and black start capability will become important concerns on 11 kV and LV networks. This will require increased generation monitoring and remote control of switchgear. Examples of cost benefits from scheduling are given, including deferred reinforcement, increased exports on non

  12. STM investigations of local potential barrier distribution of the atomic surface of graphite

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To modulate the tunneling gap with the lock-in amplifier in the scanning tunneling microscopy(STM), information of the tunneling current variation can be obtained. The local potential barrier distribution of graphite surface atoms is got by means of such technology. Compared with STM image under topography observation mode, the local potential barrier image has higher resolu tion and less influence on the tip and better anti-interference capability. Obs erved results of the graphite are given and discussed in this paper.

  13. Modeling of Thermal Distributions around a Barrier at the Interface of Coating and Substrate

    Directory of Open Access Journals (Sweden)

    Ali Sahin

    2013-01-01

    Full Text Available Due to constant heat flux, the thermal distribution around an insulated barrier at the interface of substrate and functionally graded material (FGM which are essentially two-phase particulate composites is examined in such a way that the volume fractions of the constituents vary continuously in the thickness direction. Using integral transform method, two-dimensional steady-state diffusion equation with variable conductivity is turned into constant coefficient differential equation. Reducing that equation to a singular integral equation with Cauchy type, the temperature distribution around the barrier is obtained by defining an unknown function, which is called density function, as a series expansion of orthogonal polynomials. Results are shown for different thickness and nonhomogeneity parameters of FGM.

  14. Total reaction cross sections for {sup 8}Li + {sup 90}Zr at near-barrier energies

    Energy Technology Data Exchange (ETDEWEB)

    Pakou, A.; Aslanoglou, X.; Sgouros, O.; Soukeras, V. [The University of Ioannina, Department of Physics and HINP, Ioannina (Greece); Pierroutsakou, D.; Boiano, A.; Parascandolo, C. [INFN, Sezione di Napoli, Napoli (Italy); Mazzocco, M.; Soramel, F.; Strano, E.; Torresi, D. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); INFN, Sezione di Padova, Padova (Italy); Acosta, L.; Marquinez-Duran, G.; Martel, I. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Boiano, C. [INFN, Sezione di Milano, Milano (Italy); Carbone, D.; Cavallaro, M. [INFN Laboratori Nazionali del Sud, Catania (Italy); Grebosz, J. [The Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN), Krakow (Poland); Keeley, N. [National Center for Nuclear Research, Otwock Warsaw (Poland); La Commara, M. [INFN, Sezione di Napoli, Napoli (Italy); Universita di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); Manea, C. [INFN, Sezione di Padova, Padova (Italy); Rusek, K.; Trzcinska, A. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Sanchez-Benitez, A.M. [Centro de Fisica Nuclear da Universidade de Lisboa, Lisboa (Portugal); Signorini, C. [INFN, LNL, Legnaro (Italy); Stiliaris, E. [University of Athens, Institute of Accelerating Systems and Applications and Department of Physics, Athens (Greece); Watanabe, Y.X. [High Energy Accelerator Research Organization (KEK), Institute of Particle and Nuclear Studies (IPNS), Ibaraki (Japan); Yamaguchi, H. [University of Tokyo, Center for Nuclear Study (CNS), Saitama (Japan)

    2015-05-15

    Total reaction cross sections for the radioactive nucleus {sup 8}Li on {sup 90}Zr are reported at the near-barrier energies of 18.5 and 21.5MeV, derived from quasi-elastic scattering measurements. An analysis of the quasi-elastic scattering results is performed within an optical model framework using the BDM3Y1 interaction and total reaction cross sections are deduced. These quantities, appropriately reduced, are compared with previous data obtained in elastic scattering measurements with well and weakly bound projectiles on various targets and a formula for predicting total reaction cross sections with an uncertainty of ∝ 20 % is obtained. Further on, the ratios of direct to total reaction cross sections are estimated for {sup 6,8}Li on various targets and are compared with CDCC or CRC calculations. The energy dependence of the optical potential is also discussed. (orig.)

  15. Total reaction cross sections for 8Li + 90Zr at near-barrier energies

    Science.gov (United States)

    Pakou, A.; Pierroutsakou, D.; Mazzocco, M.; Acosta, L.; Aslanoglou, X.; Boiano, A.; Boiano, C.; Carbone, D.; Cavallaro, M.; Grebosz, J.; Keeley, N.; La Commara, M.; Manea, C.; Marquinez-Duran, G.; Martel, I.; Parascandolo, C.; Rusek, K.; Sánchez-Benítez, A. M.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Strano, E.; Torresi, D.; Trzcinska, A.; Watanabe, Y. X.; Yamaguchi, H.

    2015-05-01

    Total reaction cross sections for the radioactive nucleus 8Li on 90Zr are reported at the near-barrier energies of 18.5 and 21.5MeV, derived from quasi-elastic scattering measurements. An analysis of the quasi-elastic scattering results is performed within an optical model framework using the BDM3Y1 interaction and total reaction cross sections are deduced. These quantities, appropriately reduced, are compared with previous data obtained in elastic scattering measurements with well and weakly bound projectiles on various targets and a formula for predicting total reaction cross sections with an uncertainty of % is obtained. Further on, the ratios of direct to total reaction cross sections are estimated for 6,8Li on various targets and are compared with CDCC or CRC calculations. The energy dependence of the optical potential is also discussed.

  16. A Precision Measurement of the Transverse Asymmetry AT from Quasi-elastic 3He(e,e') process, and the Neutron Magnetic Form Factor GNM at low Q2

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wang [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2002-06-01

    Electromagnetic form factors are fundamental quantities in describing the underlying electromagnetic structure of nucleons. While proton electromagnetic form factors have been determined with good precision, neutron form factors are known poorly, largely due to the lack of free neutron targets. Jefferson Lab Hall A experiment E95-001, a ''precise measurement of the transverse asymmetry AT' from the quasielastic 3He(e, e') process,'' was therefore designed to determine precisely the neutron magnetic form factor, G$n\\atop{M}$ at low momentum transfer values and was successfully completed in Spring 1999. High precision AT'data in the quasi-elastic region at Q2 values of 0.1 to 0.6 (GeV/c)2 were obtained using a high-pressure spin-exchange optically-pumped polarized 3He gas target with an average polarization of 30%, a longitudinally polarized e- beam, and two High Resolution Spectrometers: HRSe and HRSh. HRSe was employed to detect scattered electrons from the quasi-elastic kinematic region, and HRSh was employed as a elastic polarimetry to monitor the product of the beam and target polarizations. The extraction of form factors is usually model-dependent. Significant constraints on theoretical calculations are provided bu additional high precision quasi-elastic asymmetry data at Q2 values of 0.1 and 0.2 (GeV/c)2 in 3He breakup region, where effects of final state interactions (FSI) and meson exchange currents (MEC) are expected to be large [71]. G$n\\atop{M}$ is extracted from a non-relativistic Faddeev calculation which includes both FSI and MEC at Q2 values of 0.1 and 0.2 (GeV/c)2. The uncertainties of G$n\\atop{M}$ at these Q2 values are comparable to those of recent experiments with deuterium targets [58]. At the higher Q2 values from this experiment, G$n\\atop{M}$ is extracted

  17. Barrier distribution from 28Si+154Sm quasielastic scattering: Coupling effects in the fusion process

    Directory of Open Access Journals (Sweden)

    Kaur Gurpreet

    2016-01-01

    Full Text Available Barrier distribution for the 28Si+154Sm system has been extracted from large angle quasielastic scattering measurement to investigate the role of various channel couplings on fusion dynamics. The coupled channel calculations, including the collective excitation of the target and projectile, are observed to reproduce the experimental BD rather well. It seems that the role of neutron transfer, relative to collective excitation, is in fact weak in the 28Si+154Sm system even though it has positive Q-value for neutron transfer channels.

  18. Effect of parallax distribution and crosstalk on visual comfort in parallax barrier autostereoscopic display

    Science.gov (United States)

    Kim, Donghyun; Lee, Hyoung; Kim, Sung-Kyu; Sohn, Kwanghoon

    2015-05-01

    Although autostereoscopic display is considered to be mainstream in the three-dimensional (3-D) display market for the near future, practical quality problems still exist due to various challenges such as the accommodation-vergence conflict and crosstalk. A number of studies have shown that these problems reduce the visual comfort and reliability of the perceived workload. We present two experiments for investigating the effect of parallax distribution, which affects the behavior of the accommodation and vergence responses and crosstalk on visual comfort in autostereoscopic display. We measured the subjective visual scores and perceived depth position for watching under various conditions that include foreground parallax, background parallax, and crosstalk levels. The results show that the viewers' comfort is significantly influenced by parallax distribution that induces a suitable conflict between the accommodation and vergence responses of the human visual system. Moreover, we confirm that crosstalk changes significantly affect visual comfort in parallax barrier autostereoscopic display. Consequently, the results can be used as guidelines to produce or adjust the 3-D image in accordance with the characteristics of parallax barrier autostereoscopic display.

  19. Measurement of the νμ Charged Current π+ to Quasi-Elastic Cross Section Ratio on Mineral Oil in a 0.8 GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Linden, Steven K. [Yale Univ., New Haven, CT (United States)

    2011-01-01

    Charged current single pion production (CCπ+) and charged current quasi-elastic scattering (CCQE) are the most abundant interaction types for neutrinos at energies around 1 GeV, a region of great interest to oscillation experiments. The cross-sections for these processes, however, are not well understood in this energy range. This dissertation presents a measurement of the ratio of CCπ+ to CCQE cross-sections for muon neutrinos on mineral oil (CH2) in the MiniBooNE experiment. The measurement is presented here both with and without corrections for hadronic re-interactions in the target nucleus and is given as a function of neutrino energy in the range 0.4 GeV < Eν < 2.4 GeV. With more than 46,000 CCπ+ events collected in MiniBooNE, and with a fractional uncertainty of roughly 11% in the region of highest statistics, this measurement represents a dramatic improvement in statistics and precision over previous CCπ+ and CCQE measurements.

  20. Extraction of the Neutron Magnetic Form Factor from Quasi-Elastic 3He(pol)(e(pol),e') at Q^2 = 0.1 - 0.6 (GeV/c)^2

    CERN Document Server

    Anderson, B; Averett, T; Bertozzi, W; Black, T; Calarco, J; Cardman, L; Cates, G D; Chai, Z W; Chen, J P; Seonho Choi; Chudakov, E; Churchwell, S; Corrado, G S; Crawford, C; Dale, D; Deur, A; Djawotho, P; Dutta, D; Finn, J M; Gao, H; Gilman, R; Glamazdin, A V; Glashausser, C; Glöckle, W; Golak, J; Gómez, J; Gorbenko, V G; Hansen, J O; Hersman, F W; Higinbotham, D W; Holmes, R; Howell, C R; Hughes, E; Humensky, B; Incerti, S; De Jager, C W; Jensen, J S; Jiang, X; Jones, C E; Jones, M; Kahl, R; Kamada, H; Kievsky, fA; Kominis, I; Korsch, W; Krämer, K; Kumbartzki, G; Kuss, M; Lakuriqi, E; Liang, M; Liyanage, N; Le Rose, J; Malov, S; Margaziotis, D J; Martin, J W; McCormick, K; McKeown, R D; McIlhany, K; Meziani, Z E; Michaels, R; Miller, G W; Mitchell, J; Nanda, S; Pace, E; Pavlin, T; Petratos, G G; Pomatsalyuk, R I; Pripstein, D; Prout, D; Ransome, R D; Roblin, Y; Rvachev, M; Saha, A; Salmè, G; Schnee, M; Seely, J; Shin, T; Slifer, K J; Souder, P A; Strauch, S; Suleiman, R; Sutter, M; Tipton, B; Todor, L; Viviani, M; Vlahovic, B; Watson, J; Williamson, C F; Witala, H; Wojtsekhowski, B; Xiong, F; Xu, W; Yeh, J

    2006-01-01

    We have measured the spin-dependent transverse asymmetry, A_T', in quasi-elastic inclusive electron scattering from polarized 3He with high precision at Q^2 = 0.1 to 0.6 (GeV/c)^2. The neutron magnetic form factor, GMn, was extracted at Q^2 = 0.1 and 0.2 (GeV/c)^2 using a non-relativistic Faddeev calculation that includes both final-state interactions (FSI) and meson-exchange currents (MEC). In addition, GMn was extracted at Q^2 = 0.3 to 0.6 (GeV/c)^2 using a Plane Wave Impulse Approximation calculation. The accuracy of the modeling of FSI and MEC effects was tested and confirmed with a precision measurement of the spin-dependent asymmetry in the breakup threshold region of the 3He(pol)(e(pol),e') reaction. The total relative uncertainty of the extracted GMn data is approximately 3%. Close agreement was found with other recent high-precision GMn data in this Q^2 range.

  1. Measurement of double polarized asymmetries in quasi-elastic processes ${}^3\\vec{He}(\\vec{e},e' d)$ and ${}^3\\vec{He}(\\vec{e},e' p)$

    Energy Technology Data Exchange (ETDEWEB)

    Mihovilovic, Miha [Univ. of Ljubljana (Slovenia)

    2012-01-01

    This thesis is dedicated to a study of a spin-isospin structure of the polarized 3He. First, an introduction to the spin structure of 3He is given, followed by a brief overview of past experiments. The main focus of the thesis is the E05-102 experiment at Jefferson Lab, in which the reactions ${}^3\\vec{He}(\\vec{e},e' d)$ and ${}^3\\vec{He}(\\vec{e},e' p)$ in the quasi-elastic region were studied. The purpose of this experiment was to better understand the effects of the S'- and D-state contributions to the 3He ground-state wave-functions by a precise measurement of beam-target asymmetries Ax and Az in the range of recoil momenta from 0 to about 300 MeV/c. The experimental equipment utilized in these measurements is described, with special attention devoted to the calibration of the hadron spectrometer, BigBite. Results on the measured asymmetries are presented, together with first attempts at their comparison to the state-of-the art Faddeev calculations. The remaining open problems and challenges for future work are also discussed.

  2. Precise Extraction of the Neutron Magnetic Form Factor from Quasi-elastic 3He(pol)(e(pol),e') at Q^2 = 0.1-0.6 (GeV/c)^2

    Energy Technology Data Exchange (ETDEWEB)

    Jens-ole Hansen; Brian Anderson; Leonard Auerbach; Todd Averett; William Bertozzi; Tim Black; John Calarco; Lawrence Cardman; Gordon Cates; Zhengwei Chai; Jiang-Ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; G Corrado; Christopher Crawford; Daniel Dale; Alexandre Deur; Pibero Djawotho; Dipangkar Dutta; John Finn; Haiyan Gao; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Walter Gloeckle; Jacek Golak; Javier Gomez; Viktor Gorbenko; F. Hersman; Douglas Higinbotham; Richard Holmes; Calvin Howell; Emlyn Hughes; Thomas Humensky; Sebastien Incerti; Piotr Zolnierczuk; Cornelis De Jager; John Jensen; Xiaodong Jiang; Cathleen Jones; Mark Jones; R Kahl; H Kamada; A Kievsky; Ioannis Kominis; Wolfgang Korsch; Kevin Kramer; Gerfried Kumbartzki; Michael Kuss; Enkeleida Lakuriqi; Meihua Liang; Nilanga Liyanage; John LeRose; Sergey Malov; Demetrius Margaziotis; Jeffery Martin; Kathy McCormick; Robert McKeown; Kevin McIlhany; Zein-Eddine Meziani; Robert Michaels; Greg Miller; Joseph Mitchell; Sirish Nanda; Emanuele Pace; Tina Pavlin; Gerassimos Petratos; Roman Pomatsalyuk; David Pripstein; David Prout; Ronald Ransome; Yves Roblin; Marat Rvachev; Giovanni Salme; Michael Schnee; Charles Seely; Taeksu Shin; Karl Slifer; Paul Souder; Steffen Strauch; Riad Suleiman; Mark Sutter; Bryan Tipton; Luminita Todor; M Viviani; Branislav Vlahovic; John Watson; Claude Williamson; H Witala; Bogdan Wojtsekhowski; Feng Xiong; Wang Xu; Jen-chuan Yeh

    2006-05-05

    We have measured the transverse asymmetry A{sub T'} in the quasi-elastic {sup 3}/rvec He/(/rvec e/,e') process with high precision at Q{sup 2}-values from 0.1 to 0.6 (GeV/c){sup 2}. The neutron magnetic form factor G{sub M}{sup n} was extracted at Q{sup 2}-values of 0.1 and 0.2 (GeV/c){sup 2} using a non-relativistic Faddeev calculation which includes both final-state interactions (FSI) and meson-exchange currents (MEC). Theoretical uncertainties due to the FSI and MEC effects were constrained with a precision measurement of the spin-dependent asymmetry in the threshold region of {sup 3}/rvec He/(/rvec e/,e'). We also extracted the neutron magnetic form factor G{sub M}{sup n} at Q{sup 2}-values of 0.3 to 0.6 (GeV/c){sup 2} based on Plane Wave Impulse Approximation calculations.

  3. Electron energy distribution functions for modelling the plasma kinetics in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Carman, R.J. [Department of Physics, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)). E-mail: rcarman@physics.mq.edu.au; Mildren, R.P. [Centre for Lasers and Applications, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)

    2000-10-07

    In modelling the plasma kinetics in dielectric barrier discharges (DBDs), the electron energy conservation equation is often included in the rate equation analysis (rather than utilizing the local-field approximation) with the assumption that the electron energy distribution function (EEDF) has a Maxwellian profile. We show that adopting a Maxwellian EEDF leads to a serious overestimate of the calculated ionization/excitation rate coefficients and the electron mobility for typical plasma conditions in a xenon DBD. Alternative EEDF profiles are trialed (Druyvesteyn, bi-Maxwellian and bi-Druyvesteyn) and benchmarked against EEDFs obtained from solving the steady-state Boltzmann equation. A bi-Druyvesteyn EEDF is shown to be more inherently accurate for modelling simulations of xenon DBDs. (author)

  4. Numerical investigation of the spatiotemporal distribution of chemical species in an atmospheric surface barrier-discharge

    Science.gov (United States)

    Hasan, M. I.; Walsh, J. L.

    2016-05-01

    Using a one dimensional time dependent convection-reaction-diffusion model, the temporal and spatial distributions of species propagating downstream of an atmospheric pressure air surface barrier discharge was studied. It was found that the distribution of negatively charged species is more spatially spread compared to positive ions species, which is attributed to the diffusion of electrons that cool down and attach to background gas molecules, creating different negative ions downstream of the discharge region. Given the widespread use of such discharges in applications involving the remote microbial decontamination of surfaces and liquids, the transport of plasma generated reactive species away from the discharge region was studied by implementing mechanical convection through the discharge region. It was shown that increased convection causes the spatial distribution of species density to become uniform. It was also found that many species have a lower density close to the surface of the discharge as convection prevents their accumulation. While for some species, such as NO2, convection causes a general increase in the density due to a reduced residence time close to the discharge region, where it is rapidly lost through reactions with OH. The impact of the applied power was also investigated, and it was found that the densities of most species, whether charged or neutral, are directly proportional to the applied power.

  5. Barrier distributions and signatures of transfer channels in the Ca40+Ni58,64 fusion reactions at energies around and below the Coulomb barrier

    Science.gov (United States)

    Bourgin, D.; Courtin, S.; Haas, F.; Stefanini, A. M.; Montagnoli, G.; Goasduff, A.; Montanari, D.; Corradi, L.; Fioretto, E.; Huiming, J.; Scarlassara, F.; Rowley, N.; Szilner, S.; Mijatović, T.

    2014-10-01

    Background: The nuclear structure of colliding nuclei is known to influence the fusion process. Couplings of the relative motion to nuclear shape deformations and vibrations lead to an enhancement of the sub-barrier fusion cross section in comparison with the predictions of one-dimensional barrier penetration models. This enhancement is explained by coupled-channels calculations including these couplings. The sub-barrier fusion cross section is also affected by nucleon transfer channels between the colliding nuclei. Purpose: The aim of the present experiment is to investigate the influence of the projectile and target nuclear structures on the fusion cross sections in the Ca40+Ni58 and Ca40+Ni64 systems. Methods: The experimental and theoretical fusion excitation functions as well as the barrier distributions were compared for these two systems. Coupled-channels calculations were performed using the ccfull code. Results: Good agreement was found between the measured and calculated fusion cross sections for the Ca40+Ni58 system. The situation is different for the Ca40+Ni64 system where the coupled-channels calculations with no nucleon transfer clearly underestimate the fusion cross sections below the Coulomb barrier. The fusion excitation function was, however, well reproduced at low and high energies by including the coupling to the neutron pair-transfer channel in the calculations. Conclusions: The nuclear structure of the colliding nuclei influences the fusion cross sections below the Coulomb barrier for both Ca40+Ni58,64 systems. Moreover, we highlighted the effect of the neutron pair-transfer channel on the fusion cross sections in Ca40+Ni64.

  6. A multilayer ΔE-E R telescope for breakup reactions at energies around the Coulomb barrier

    Science.gov (United States)

    Ma, Nan-Ru; Lin, Cheng-Jian; Wang, Jian-Song; Yang, Lei; Wang, Dong-Xi; Zheng, Lei; Xu, Shi-Wei; Sun, Li-Jie; Jia, Hui-Ming; Ma, Jun-Bing; Ma, Peng; Jin, Shi-Lun; Bai, Zhen; Yang, Yan-Yun; Xu, Xin-Xing; Zhang, Gao-Long; Yang, Feng; He, Jian-Jun; Zhang, Huan-Qiao; Liu, Zu-Hua

    2016-11-01

    The breakup reactions of weakly-bound nuclei at energies around the Coulomb barrier and the corresponding coupling effect on the other reaction channels are hot topics nowadays. To overcome the difficulty in identifying both heavier and lighter fragments simultaneously, a new kind of ionization-chamber based detector telescope has been designed and manufactured. It consists of a PCB ionization chamber and three different thickness silicon detectors installed inside the chamber, which form a multilayer ΔE-E R telescope. The working conditions were surveyed by using an α source. An in-beam test experiment shows that the detector has good particle identification for heavy particles like 17F and 16O as well as light particles like protons and alpha particles. The measured quasi-elastic scattering angular distribution and the related discussions for 17F+208Pb are presented. Supported by National Key Basic Research Development Program of China (2013CB834404) and National Natural Science Foundation of China (11375268, 11475263, U1432127, U1432246).

  7. Distribution, abundance and diversity of crustose coralline algae on the Great Barrier Reef

    Science.gov (United States)

    Dean, Angela J.; Steneck, Robert S.; Tager, Danika; Pandolfi, John M.

    2015-06-01

    The Great Barrier Reef (GBR) is the world's largest coral reef ecosystem. Crustose coralline algae (CCA) are important contributors to reef calcium carbonate and can facilitate coral recruitment. Despite the importance of CCA, little is known about species-level distribution, abundance, and diversity, and how these vary across the continental shelf and key habitat zones within the GBR. We quantified CCA species distributions using line transects ( n = 127) at 17 sites in the northern and central regions of the GBR, distributed among inner-, mid-, and outer-shelf regions. At each site, we identified CCA along replicate transects in three habitat zones: reef flat, reef crest, and reef slope. Taxonomically, CCA species are challenging to identify (especially in the field), and there is considerable disagreement in approach. We used published, anatomically based taxonomic schemes for consistent identification. We identified 30 CCA species among 12 genera; the most abundant species were Porolithon onkodes, Paragoniolithon conicum (sensu Adey), Neogoniolithon fosliei, and Hydrolithon reinboldii. Significant cross-shelf differences were observed in CCA community structure and CCA abundance, with inner-shelf reefs exhibiting lower CCA abundance than outer-shelf reefs. Shelf position, habitat zone, latitude, depth, and the interaction of shelf position and habitat were all significantly associated with variation in composition of CCA communities. Collectively, shelf position, habitat, and their interaction contributed to 22.6 % of the variation in coralline communities. Compared to mid- and outer-shelf sites, inner-shelf sites exhibited lower relative abundances of N. fosliei and Lithophyllum species. Reef crest habitats exhibited greater abundance of N. fosliei than reef flat and reef slope habitats. Reef slope habitats exhibited lower abundance of P. onkodes, but greater abundance of Neogoniolithon clavycymosum than reef crest and reef slope habitats. These findings

  8. The distribution and abundance of reef-associated predatory fishes on the Great Barrier Reef

    Science.gov (United States)

    Emslie, Michael J.; Cheal, Alistair J.; Logan, Murray

    2017-09-01

    Predatory fishes are important components of coral-reef ecosystems of the Great Barrier Reef (GBR) through both the ecological functions they perform and their high value to recreational and commercial fisheries, estimated at 30 million in 2014. However, management of GBR predatory fish populations is hampered by a lack of knowledge of their distribution and abundance, aside from that of the highly targeted coral trout ( Plectropomus spp. and Variola spp.). Furthermore, there is little information on how these fishes respond to environmental stressors such as coral bleaching, outbreaks of coral-feeding starfishes ( Acanthaster planci) and storms, which limits adaptive management of their populations as the frequency or severity of such natural disturbances increases under climate change. Here, we document the distribution and abundance of 48 species of reef-associated predatory fishes and assess their vulnerability to a range of natural disturbances. There were clear differences in predatory fish assemblages across the continental shelf, but many species were widespread, with few species restricted to either inshore or offshore waters. There was weak latitudinal structure with only a few species restricted to either the northern or southern GBR. On the whole, predatory fishes were surprisingly resistant to the effects of disturbance, with few clear changes in abundance or species richness following 66 documented disturbances of varying magnitudes.

  9. Weak Quasi-elastic Production of Hyperons

    CERN Document Server

    Singh, S K

    2006-01-01

    The quasielastic weak production of $\\Lambda$ and $\\Sigma$ hyperons from nucleons and nuclei induced by antineutrinos is studied in the energy region of some ongoing neutrino oscillation experiments in the intermediate energy region. The hyperon nucleon transition form factors determined from neutrino nucleon scattering and an analysis of high precision data on semileptonic decays of neutron and hyperons using SU(3) symmetry have been used. The nuclear effects due to Fermi motion and final state interaction effects due to hyperon nucleon scattering have also been studied. The numerical results for differential and total cross sections have been presented.

  10. Ring distributions leading to species formation: a global topographic analysis of geographic barriers associated with ring species

    Directory of Open Access Journals (Sweden)

    Monahan William B

    2012-03-01

    relative importance of features that define barriers, (ii can be replicated using any kind of continuously distributed environmental variable, and (iii generates spatially explicit hypotheses of geographic species formation. The methods developed here - combined with study of the geographical ecology and genetics of taxa in their environments - should enable recognition of ring species phenomena throughout the world.

  11. Effects of airflow on the distribution of filaments in atmospheric AC dielectric barrier discharge

    Science.gov (United States)

    Fan, Zhihui; Qi, Haicheng; Liu, Yidi; Yan, Huijie; Ren, Chunsheng

    2016-12-01

    Atmospheric-pressure dielectric barrier discharge (DBD) accompanied by airflow has attracted a significant attention for its extensive applications. In this paper, the effects of airflow on the characteristics of the atmospheric air DBD plasma are experimentally investigated using the DBD reactor excited by a 15 kHz AC power source. In order to study the discharge filaments distribution at different flow rates, transparent conductive indium tin oxide film is used as the upper electrode, and quartz glasses are used as insulated dielectrics. Experiment results prove that the breakdown voltage is decreased and more current pulses with declined amplitudes are produced when the airflow is introduced into the discharge gap. It is confirmed that although the discharge seems to be diffuse in the presence of airflow to the naked eyes, the discharge mode remains filamentary in the intensified charge-coupled device images within a single AC cycle. By acquiring the images with a different exposure time, it can be recognized that the discharge filaments move along the flow field direction with a velocity less than the corresponding flow rate. The movement of discharge filaments is attributed to the motion of the charge induced by the airflow.

  12. Theory of potential distributions in abrupt heterojunction crystalline semiconductor devices: Treatment of Schottky barriers and rectifiers

    Science.gov (United States)

    Mohammad, S. Noor

    1988-03-01

    present formulas a general form for potential distribution in Schottky barriers has been derived. The relation reduces to that of Gummel and Scarfetter [J. Appl. Phys. 38, 2148 (1967)] under special conditions. Theoretical reasons underlying the lack of rectification in various n-N HJs have been analyzed. In light of this analysis, a theoretical model in terms of many-body electron-electron and electron-donor interactions, and in terms of lowering of band edge in the vicinity of transition region, has been proposed. Numerical results obtained from this model for n-GaAs agree remarkably with observations from experimental measurements.

  13. Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Malikova, N

    2005-09-15

    Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

  14. Influence of base impurity distribution on the photoelectric properties of surface-barrier UV photodetectors

    Directory of Open Access Journals (Sweden)

    Bobrenko Yu. N.

    2012-10-01

    Full Text Available The article presents the study on spectral, capacitance-voltage and current-voltage characteristics of surface-barrier structures based on A2B6 composition with different carrier concentration profiles in space-charge region sensitive to ultraviolet range and perspective for ultraviolet sensor application.

  15. New constraints on the spatial distribution and morphology of the Halimeda bioherms of the Great Barrier Reef, Australia

    Science.gov (United States)

    McNeil, Mardi A.; Webster, Jody M.; Beaman, Robin J.; Graham, Trevor L.

    2016-12-01

    Halimeda bioherms occur as extensive geological structures on the northern Great Barrier Reef (GBR), Australia. We present the most complete, high-resolution spatial mapping of the northern GBR Halimeda bioherms, based on new airborne lidar and multibeam echosounder bathymetry data. Our analysis reveals that bioherm morphology does not conform to the previous model of parallel ridges and troughs, but is far more complex than previously thought. We define and describe three morphological sub-types: reticulate, annulate, and undulate, which are distributed in a cross-shelf pattern of reduced complexity from east to west. The northern GBR bioherms cover an area of 6095 km2, three times larger than the original estimate, exceeding the area and volume of calcium carbonate in the adjacent modern shelf-edge barrier reefs. We have mapped a 1740 km2 bioherm complex north of Raine Island in the Cape York region not previously recorded, extending the northern limit by more than 1° of latitude. Bioherm formation and distribution are controlled by a complex interaction of outer-shelf geometry, regional and local currents, coupled with the morphology and depth of continental slope submarine canyons determining the delivery of cool, nutrient-rich water upwelling through inter-reef passages. Distribution and mapping of Halimeda bioherms in relation to Great Barrier Reef Marine Park Authority bioregion classifications and management zones are inconsistent and currently poorly defined due to a lack of high-resolution data not available until now. These new estimates of bioherm spatial distribution and morphology have implications for understanding the role these geological features play as structurally complex and productive inter-reef habitats, and as calcium carbonate sinks which record a complete history of the Holocene post-glacial marine transgression in the northern GBR.

  16. Heavy-ion fusion cross sections and barrier distributions for {sup 12}C, {sup 16}O, {sup 28}Si and {sup 35}Cl on {sup 92}Zr

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K.P. [P G Department of Physics and Research Centre, Payyanur College, Payyanur-670327 (India)], E-mail: drkpsanthosh@gmail.com; Bobby Jose, V. [P G Department of Physics and Research Centre, Payyanur College, Payyanur-670327 (India); Joseph, Antony; Varier, K.M. [Department of Physics, University of Calicut, Calicut-673635 (India)

    2009-02-01

    The fusion excitation functions and barrier distributions for the fusion of {sup 12}C, {sup 16}O, {sup 28}Si and {sup 35}Cl on {sup 92}Zr have been calculated using one-dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential. Calculated results are compared with experimental data and CC calculations using code CCFULL. At and above the barrier the computed cross sections match well with the experimental data, whereas below the barrier, calculations with nuclear surface tension coefficient improved by Reisdorf in the proximity potential give good fit. Reduced reaction cross sections for the systems have also been described.

  17. X-Ray Elastic Constants and Residual Stress Distributions of Zirconia Thermal Barrier Coating

    OpenAIRE

    鈴木, 賢治; 町屋, 修太郎; 田中, 啓介; 坂井田, 喜久; SUZUKI, Kenji; Machiya, Syutaro; Tanaka, Keisuke; Sakaida, Yoshihisa

    2001-01-01

    Accurate values of X-ray elastic constants are required for a reliable stress measurement of thermal barrier coating films (TBC films). In this paper, atmosphere and pressureless plasma sprayed TBC films were removed from substrates, then X-ray elastic constants of both TBC films were determained by using newly developed tensile jig. For the atmosphere plasma sprayed film, the value of the mechanical elastic constant was much smaller than the X-ray elastic constant owing to cracks or pores ex...

  18. Spin distribution measurement for 64Ni + 100Mo at near and above barrier energies

    Directory of Open Access Journals (Sweden)

    Singh Varinderjit

    2015-01-01

    Full Text Available Spin distribution measurements were performed for the reaction 64Ni + 100Mo at three beam energies ranging from 230 to 260 MeV. Compound nucleus (CN spin distributions were obtained channel selective for each evaporation residue populated by the de-excitation cascade. A comparison of the spin distribution at different beam energies indicates that its slope becomes steeper and steeper with increasing beam energy. This change in slope of the spin distribution is mainly due to the onset of fission competition with particle evaporation at higher beam energies.

  19. Measurements of angular distributions for7Li elastically scattered from58Ni at energies around the Coulomb barrier

    Science.gov (United States)

    Amador-Valenzuela, P.; Aguilera, E. F.; Martinez-Quiroz, E.; Lizcano, D.; Morales-Rivera, J. C.

    2017-07-01

    Recently, experimental measurements of elastic scattering angular distributions for the system7Li+58Ni at ten different energies around the Coulomb barrier were made by the Heavy-Ion Group. The measurements were made at the Tandem Van de Graaff Particle Accelerator Laboratory in the National Institute for Nuclear Research (ININ) in Mexico. In this work, preliminary elastic scattering angular distributions for five energies (E lab , = 12.0, 12.5, 13.0, 13.5 and 14.22 MeV) are presented. The preliminary experimental data were analyzed using the São Paulo Optical Model Potential (SPP) which is based on a double-folding potential, reproducing very well these data. A comparison is made with old data reported back in 1973 and in 2012. Further analysis is in progress in order to fully understand this particular system, specially because7Li is known to be a weakly bound nucleus.

  20. Patterns in the distribution of coral communities across the central Great Barrier Reef

    Science.gov (United States)

    Done, T. J.

    1982-10-01

    Despite the pre-eminence of the Great Barrier Reef, there has been little systematic description of its biotic communities, and in particular, of the corals themselves. Only recently have the problems of coral taxonomy been sufficiently resolved to allow a beginning to be made in rectifying this deficiency. The present study describes seventeen assemblages of corals which occupy the major habitat types found in and near the central Great Barrier Reef. The habitats studied range from the wave swept reef flats of Coral Sea atolls to the slopes of small reefs occupying sheltered, muddy conditions near the coast. These, and the array of reefs between, have characteristic suites of coral communities which provide the basis for a classification of reefs into non- Acropora reefs and various Acropora reefs. It is speculated that the faunistic differences are maintained because reefs are primarily self-seeded and because the majority of larvae from external sources are of species which are already present. The greatest diversity of both species and community types was found on reefs near the middle of the continental shelf, while the oceanic atolls and nearshore silt-affected reefs are almost equally depauperate.

  1. Influence of capillary barrier effect on biogas distribution at the base of passive methane oxidation biosystems: Parametric study.

    Science.gov (United States)

    Ahoughalandari, Bahar; Cabral, Alexandre R

    2017-05-01

    The efficiency of methane oxidation in passive methane oxidation biosystems (PMOBs) is influenced by, among other things, the intensity and distribution of the CH4 loading at the base of the methane oxidation layer (MOL). Both the intensity and distribution are affected by the capillary barrier that results from the superposition of the two materials constituting the PMOB, namely the MOL and the gas distribution layer (GDL). The effect of capillary barriers on the unsaturated flow of water has been well documented in the literature. However, its effect on gas flow through PMOBs is still poorly documented. In this study, sets of numerical simulations were performed to evaluate the effect of unsaturated hydraulic characteristics of the MOL material on the value and distribution of moisture and hence, the ease and uniformity in the distribution of the upward flow of biogas along the GDL-MOL interface. The unsaturated hydraulic parameters of the materials used to construct the experimental field plot at the St-Nicephore landfill (Quebec, Canada) were adopted to build the reference simulation of the parametric study. The behavior of the upward flow of biogas for this particular material was analyzed based on its gas intrinsic permeability function, which was obtained in the laboratory. The parameters that most influenced the distribution and the ease of biogas flow at the base of the MOL were the saturated hydraulic conductivity and pore size distribution of the MOL material, whose effects were intensified as the slope of the interface increased. The effect of initial dry density was also assessed herein. Selection of the MOL material must be made bearing in mind that these three parameters are key in the effort to prevent unwanted restriction in the upward flow of biogas, which may result in the redirection of biogas towards the top of the slope, leading to high CH4 fluxes (hotspots). In a well-designed PMOB, upward flow of biogas across the GDL-MOL interface is

  2. Electrostatic Barrier Against Dust Growth in Protoplanetary Disks. I. Classifying the Evolution of Size Distribution

    CERN Document Server

    Okuzumi, Satoshi; Takeuchi, Taku; Sakagami, Masa-aki

    2010-01-01

    Collisional growth of submicron-sized dust grains into macroscopic aggregates is the first step of planet formation in protoplanetary disks. These aggregates are considered to carry nonzero negative charges in the weakly ionized gas disks, but its effect on their collisional growth has not been fully understood so far. In this paper, we investigate how the charging of dust aggregates affects the evolution of their size distribution properly taking into account the charging mechanism in a weakly ionized gas. To clarify the role of the size distribution, we divide our analysis into two steps. First, we analyze the collisional growth of charged aggregates assuming a monodisperse (i.e., narrow) size distribution. We show that the monodisperse growth stalls due to the electrostatic repulsion when a certain condition is met, as is already expected in the previous work. Second, we numerically simulate dust coagulation using Smoluchowski's method to see how the outcome changes when the size distribution is allowed to...

  3. Patterns in the distribution of sponge populations across the central Great Barrier Reef

    Science.gov (United States)

    Wilkinson, Clive R.; Cheshire, Anthony C.

    1989-12-01

    Coral reef sponge populations were surveyed at two spatial scales: different depths and different reef locations across the continental shelf of the central Great Barrier Reef. The surveys were conducted on the forereef slopes of 12 reefs from land-influenced, inner-shelf reefs to those in the oligotrophic waters of the Coral Sea. Few sponges occur in shallow waters and the largest populations are found between 10 and 30 m depth. Sponges are apparently excluded from shallow waters because of excessive turbulence and possibly by high levels of damaging light. Sponge biomass is highest on the innershelf reefs and decreases away from the coast, whereas abundance is generally higher on middle-shelf reefs. There are considerable overlaps in the species composition on middle-, outer-shelf and Coral Sea reefs, but those on inner-shelf reefs are significantly different. The nature and size of sponge populations reflect environmental conditions across the continental shelf. The larger inner-shelf populations probably reflect higher levels of organic and inorganic nutrients and reduced amounts of physical turbulence, whereas sponges on reefs further from shore may be able to resist greater turbulence but appear more sensitive to the effects of fine sediments. These latter populations are smaller, reflecting the reduced availability of organic matter, however, many of these sponges rely on cyanobacterial symbionts to augment nutrition in these clearer, more oligotrophic waters.

  4. Environmental factors associated with the spatial distribution of crustose coralline algae on the Great Barrier Reef

    Science.gov (United States)

    Fabricius, K.; De'ath, G.

    2001-05-01

    Crustose coralline algae (CCA) fulfill two key functional roles in coral reef ecosystems: they contribute significantly to reef calcification, and they induce larval settlement of many benthic organisms. Percentage cover of CCA, and environmental conditions, were visually estimated on 144 reefs of the Great Barrier Reef between 10 and 24° latitude S. Reefs were located across the shelf and ranged from turbid near-shore reefs close to rivers to clean-water reefs hundreds of kilometers from coastal influences. On each reef, two sites were surveyed between 0.5 and 18 m depth. Strong cross-shelf trends occurred in cover of CCA, amount of sediment deposited, water clarity, and slope angle. Relative distance across the shelf and sedimentation jointly explained 84% of variation in CCA cover. Three regions running parallel to the shore were identified, with a mean CCA cover of 20% cover on the outer half of the shelf, with a narrow transition region between the two. Within each region, the cover of CCA was unrelated to distance across the shelf, but was related to the sedimentary environment, being relatively higher on reefs with low sediment deposits. On the inner third of the shelf, the most sediment-exposed reefs were unsuitable habitats for CCA. The inverse relationship between CCA and sediment has implications for the recruitment of CCA-specialised organisms, and for rates of reef calcification.

  5. Distribution of vipera ammodytes toxic phospholipase A in the cat and its ability to cross the blood-brain barrier.

    Science.gov (United States)

    Gubensek, F; Ritonja, A; Cotic, V; Kozelj, G; Pihler, B; Oresković, D; Bulat, M

    1982-01-01

    Several phospholipases A could be isolated from the venom of the European viper, Vipera ammodytes, having different specific activities toward egg lecithin and different lethalities. The most lethal of these enzymes is fraction "k2" having an intravenous LD50 for white mice of 0.021 mg per kg and a specific activity of 280 microM/min mg at 40 degrees C. The enzyme could be labeled with 131I without loosing its enzymatic activity and lethality. The passage of this enzyme from blood into cerebrospinal fluid (CSF) was followed in anesthetized cats. Approximately 1% of the blood level of the enzyme was found in CSF indicating the ability of this protein to penetrate the blood-brain barrier. Although the lethality of fraction "k2" becomes as low as 0.085 microgram/kg when applied intraventricularly, it is not very likely that the central effects of this fraction are of major importance in envenomation since the distribution pattern of the labeled enzyme shows that most of the protein remains in liver, lungs and kidneys, presumably non-selectively bound to membranes and only 0.2% of the injected fraction can reach the brain. Relatively high amount of enzyme was also found in the diaphragm. The penetration of the blood-brain barrier of the radiolabeled phospholipase is within the limits for the proteins of this size (M.w. 14500).

  6. The future distribution of river fish: The complex interplay of climate and land use changes, species dispersal and movement barriers.

    Science.gov (United States)

    Radinger, Johannes; Essl, Franz; Hölker, Franz; Horký, Pavel; Slavík, Ondřej; Wolter, Christian

    2017-05-13

    The future distribution of river fishes will be jointly affected by climate and land use changes forcing species to move in space. However, little is known whether fish species will be able to keep pace with predicted climate and land use-driven habitat shifts, in particular in fragmented river networks. In this study, we coupled species distribution models (stepwise boosted regression trees) of 17 fish species with species-specific models of their dispersal (fish dispersal model FIDIMO) in the European River Elbe catchment. We quantified (i) the extent and direction (up- vs. downstream) of predicted habitat shifts under coupled "moderate" and "severe" climate and land use change scenarios for 2050, and (ii) the dispersal abilities of fishes to track predicted habitat shifts while explicitly considering movement barriers (e.g., weirs, dams). Our results revealed median net losses of suitable habitats of 24 and 94 river kilometers per species for the moderate and severe future scenarios, respectively. Predicted habitat gains and losses and the direction of habitat shifts were highly variable among species. Habitat gains were negatively related to fish body size, i.e., suitable habitats were projected to expand for smaller-bodied fishes and to contract for larger-bodied fishes. Moreover, habitats of lowland fish species were predicted to shift downstream, whereas those of headwater species showed upstream shifts. The dispersal model indicated that suitable habitats are likely to shift faster than species might disperse. In particular, smaller-bodied fish (species might substantially be restricted by movement barriers to respond to predicted climate and land use changes, while smaller-bodied species are rather restricted by their specific dispersal ability. © 2017 John Wiley & Sons Ltd.

  7. Diet and cross-shelf distribution of rabbitfishes (f. Siganidae) on the northern Great Barrier Reef: implications for ecosystem function

    Science.gov (United States)

    Hoey, A. S.; Brandl, S. J.; Bellwood, D. R.

    2013-12-01

    Herbivorous fishes are a critical functional group on coral reefs, and there is a clear need to understand the role and relative importance of individual species in reef processes. While numerous studies have quantified the roles of parrotfishes and surgeonfishes on coral reefs, the rabbitfishes (f. Siganidae) have been largely overlooked. Consequently, they are typically viewed as a uniform group of grazing or browsing fishes. Here, we quantify the diet and distribution of rabbitfish assemblages on six reefs spanning the continental shelf in the northern Great Barrier Reef. Our results revealed marked variation in the diet and distribution of rabbitfish species. Analysis of stomach contents identified four distinct groups: browsers of leathery brown macroalgae ( Siganus canaliculatus, S. javus), croppers of red and green macroalgae ( S. argenteus, S. corallinus, S. doliatus, S. spinus) and mixed feeders of diverse algal material, cyanobacteria, detritus and sediment ( S. lineatus, S. punctatissimus, S. punctatus, S. vulpinus). Surprisingly, the diet of the fourth group ( S. puellus) contained very little algal material (22.5 %) and was instead dominated by sponges (69.1 %). Together with this variation in diet, the distribution of rabbitfishes displayed clear cross-shelf variation. Biomass was greatest on inner-shelf reefs (112.7 ± 18.2 kg.ha-1), decreasing markedly on mid- (37.8 ± 4.6 kg.ha-1) and outer-shelf reefs (9.7 ± 2.2 kg.ha-1). This pattern was largely driven by the browsing S. canaliculatus that accounted for 50 % of the biomass on inner-shelf reefs, but was absent in mid- and outer-shelf reefs. Mixed feeders, although primarily restricted to the reef slope and back reef habitats, also decreased in abundance and biomass from inshore to offshore, while algal cropping taxa were the dominant group on mid-shelf reefs. These results clearly demonstrate the extent to which diet and distribution vary within the Siganidae and emphasise the importance of

  8. Regional-scale variation in the distribution and abundance of farming damselfishes on Australia's Great Barrier Reef

    KAUST Repository

    Emslie, Michael J.

    2012-03-15

    Territorial damselfishes that manipulate ("farm") the algae in their territories can have a marked effect on benthic community structure and may influence coral recovery following disturbances. Despite the numerical dominance of farming species on many reefs, the importance of their grazing activities is often overlooked, with most studies only examining their roles over restricted spatial and temporal scales. We used the results of field surveys covering 9.5° of latitude of the Great Barrier Reef to describe the distribution, abundance and temporal dynamics of farmer communities. Redundancy analysis revealed unique subregional assemblages of farming species that were shaped by the combined effects of shelf position and, to a lesser extent, by latitude. These spatial patterns were largely stable through time, except when major disturbances altered the benthic community. Such disturbances affected the functional guilds of farmers in different ways. Since different guilds of farmers modify benthic community structure and affect survival of juvenile corals in different ways, these results have important implications for coral recovery following disturbances. © 2012 Springer-Verlag.

  9. Particle-in-Cell Simulation for the Control of Electron Energy Distribution of Dielectric Barrier Discharges at Atmospheric Pressure

    Science.gov (United States)

    Bae, Hyo Won; Yel Lee, Jung; Lee, Ho-Jun; Lee, Hae June

    2011-10-01

    Recently, atmospheric pressure plasmas attract lots of interests for the useful applications such as surface modification and bio-medical treatment. In this study, a particle-in-cell Monte Carlo collision (PIC-MCC) simulation was adopted to investigate the discharge characteristics of a planar micro dielectric barrier discharge (DBD) with a driving frequency from 1 MHz to 50 MHz and with a gap distance from 60 to 500 micrometers. The variation of control parameters such as the gap distance, the driving wave form, and the applied voltage results in the change in the electron energy distribution function (EEDF). Through the relation between the ionization mean free path and the gap size, a significant change of EEDFs is achievable with the decrease of gap distance. Therefore, it is possible to categorize the operation range of DBDs for its applications by controlling the interactions between plasmas and neutral gas for the generation of preferable radicals. This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20104010100670).

  10. Experimental determination of the nucleus-nucleus potential and the density of sup 1 sup 8 O from quasi-elastic cross sections of targets in the f-p shell

    CERN Document Server

    Rossi, E S

    2001-01-01

    Experimental data for elastic and inelastic (2 sub 1 sup +) scattering and one or two neutron transfer processes for the systems sup 1 sup 8 O + sup 5 sup 8 sup , sup 6 sup 0 Ni at the sub barrier bombarding energies (34,5 MeV <= E sub L sub A sub B ( sup 1 sup 8 O) <= 38,0 MeV) are presented in this work. With an optical model data analysis, the corresponding nuclear potentials were obtained in the surface interaction region. These experimental potentials were compared with those from double folding theoretical calculations, and with the potentials for systems with sup 1 sup 6 O as the projectile. The experimental potentials describe the one neutron transfer process for the same systems reasonably well. The sup 1 sup 8 O ground state density in the surface region was obtained experimentally for the first time. A comparison with the sup 1 sup 6 O nuclear density has made possible the determination of the density of the two extra neutrons in the sup 1 sup 8 O nucleus.

  11. The subcellular distribution of aquaporin 5 in the cochlea reveals a water shunt at the perilymph-endolymph barrier.

    Science.gov (United States)

    Hirt, B; Penkova, Z H; Eckhard, A; Liu, W; Rask-Andersen, H; Müller, M; Löwenheim, H

    2010-07-28

    Aquaporins are membrane water channel proteins that have also been identified in the cochlea. Auditory function critically depends on the homeostasis of the cochlear fluids perilymph and endolymph. In particular, the ion and water regulation of the endolymph is essential for sensory transduction. Within the cochlear duct the lateral wall epithelium has been proposed to secrete endolymph by an aquaporin-mediated flow of water across its epithelial tight junction barrier. This study identifies interspecies differences in the cellular distribution of aquaporin 5 (AQP5) in the cochlear lateral wall of mice, rats, gerbils and guinea pigs. In addition the cellular expression pattern of AQP5 is described in the human cochlea. Developmental changes in rats demonstrate longitudinal and radial gradients along the cochlear duct. During early postnatal development a pancochlear expression is detected. However a regression to the apical quadrant and limitation to outer sulcus cells (OSCs) is observed in the adult. This developmental loss of AQP5 expression in the basal cochlear segments coincides with a morphological loss of contact between OSCs and the endolymph. At the subcellular level, AQP5 exhibits polarized expression in the apical plasma membrane of the OSCs. Complementary, the basolateral membrane in the root processes of the OSCs exhibits AQP4 expression. This differential localization of AQP5 and AQP4 in the apical and basolateral membranes of the same epithelial cell type suggests a direct aquaporin-mediated transcellular water shunt between the perilymph and endolymph in the OSCs of the cochlear lateral wall. In the human cochlea these findings may have pathophysiological implications attributed to a dysfunctional water regulation by AQP5 such as endolymphatic hydrops (i.e. in Meniere's disease) or sensorineural hearing loss (i.e. in Sjögren's syndrome).

  12. Quasi-Elastic Electron-Deuteron Scattering and Calculation of Neutron Electromagnetic Form Factors at Q2 = 1.75 to 4.00 (GeV/c)2

    Institute of Scientific and Technical Information of China (English)

    N. Ghahramany; M. Vaez zadeh Asadi; G.R. Boroun

    2003-01-01

    Electric and Magnetic form factors of neutron are calculated via electron-deuteron scattering at 1.511 ~5.507 GeV energy using SLAC group data. Our results show that the neutron electric form factor is not equal to zero;rather it has a small value, indicating that in spite of the fact that total charge is almost neutral, there is a nonuniformcharge distribution within the neutron, and that magnetic form factor follows the dipole fit.

  13. Study of the angular energy distribution of secondary gamma radiation resulting from interactions of reactor neutrons with iron and lead barriers

    Energy Technology Data Exchange (ETDEWEB)

    Makarious, A.S.; Maayouf, R.M.A.; Megahid, R.M. (Atomic Energy Establishment, Inshas (Egypt))

    1980-07-01

    The present work deals with the experimental study of the angular energy distributions of the secondary gamma-radiation resulting from interaction of reactor neutrons with iron and lead barriers of infinite diameters and of 5 cm thickness. The measurements were carried out both with the bare neutron beam, emitted from the ET-RR-1 reactor, and with the beam being transmitted through a B/sub 4/C filter. The pulse height distributions of gamma-rays, emitted from the used barriers, were measured with a gamma-ray spectrometer with a single stilbene scintillator. The experimental results were compared with theoretical calculations carried out using a multigroup coupled neutron gamma cross-sections and a discrete ordinates transport theory code. The comparison shows a reasonable agreement between both experimental results and theoretical calculations.

  14. Acute treatment with kerosene damages the dermal barrier and alters the distribution of topically applied benzo(a)pyrene in mice.

    Science.gov (United States)

    LaDow, Kathy; Schumann, Brenda L; Luse, Nicole; Warshawsky, Dave; Pickens, William L; Hoath, Steven B; Talaska, Glenn

    2011-12-01

    The dermal route is important in many occupational exposures. Some materials may reduce the barrier function of the skin to enhance absorption and effect on internal organs. We have reported previously that kerosene cleaning following treatment with used engine oil increased DNA adduct levels in the lungs of mice compared with animals treated with used oil alone. To investigate what other physiological parameters might be affected by kerosene, we conducted in vitro and in vivo measurements of skin barrier function. We also topically applied (3)H-BAP(100 nM in 25 μL acetone) and washed half the mice with 25 μL kerosene 1 hr after carcinogen application. Groups of four mice were euthanized from 1 to 72 hr after treatment. Skin, lungs, and livers were harvested from each animal and stored separately. Kerosene application reduced the barrier function of the skin in vitro beyond the effect of the acetone vehicle and the vehicle plus BAP. In vivo studies indicated that kerosene treatment reduced the barrier function at 4 and 8 hr post application and that the barrier function recovered at 24 hr after a single treatment. The fraction of the radiolabel remaining in the skin of animals treated with (3)H-BAP and washed with kerosene was significantly less than those not washed, beginning at 24 hr (pKerosene treatment compromises dermal barrier function and the ability of the skin to retain water, enhances carcinogen absorption, and alters organ distribution. This appears to contribute to the increase in BAP DNA adducts we reported earlier.

  15. The rotational barrier of ethane and some of its hexasubstituted derivatives in terms of the forces acting on the electron distribution.

    Science.gov (United States)

    Cortés-Guzmán, Fernando; Cuevas, Gabriel; Martín Pendás, Ángel; Hernández-Trujillo, Jesús

    2015-07-15

    A novel and alternative explanation of the rotational barrier of ethane and several hexasubstituted derivatives, CX3CX3 (X = H, F, CH3, Cl, Br), is suggested based on the evaluation of the properties of the electron distribution. The forces exerted on the electron density of the topological atoms making up a molecule, the Ehrenfest forces, are analyzed and, with the help of the virial theorem, they are used to explain the experimental rotational barriers. According to this approach, the barrier is mainly a consequence of the decrease of the always attractive Ehrenfest forces (EFs) linking the two C atoms. In addition, the behavior of the EFs is related to a decrease of stability of the central C atoms, which is not compensated by the stabilization of the substituents. Also, during rotation from the staggered to the equilibrium conformation, the electron density at the C-C bond critical point and the electron delocalization between C atoms decrease and are accompanied by an increase of electron delocalization between the substituents. According to the analysis of the EF field lines and to the behavior of the integrated forces, the rotational barrier cannot be explained as a result of any repulsive forces acting on the electron density, although a possible interpretation of the quantum force that balances the EF in stationary states as a measure of traditional Pauli repulsions is also examined.

  16. Quasi-elastic neutron scattering studies of protein dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rorschach, H.E.

    1991-03-20

    The techniques of X-ray and neutron scattering that have been so successfully applied to the study of the structure of biological macromolecules have in recent years been also used for the study of the thermal motion of these molecules. The diffraction of X-rays has been widely used to investigate the high-frequency motion of the heavy-atom residues of proteins. In these studies, the mean-square thermal amplitudes can be determined from the intensities of the sharp structural lines obtained from single crystals of the hydrated proteins. Similar information can be obtained on lighter atoms from the study of the neutron scattering from single crystals. The results of these measurements are coupled closely to the rapidly developing field of theoretical molecular dynamics which is now being applied to study the dynamics of large biological molecules. This report discusses research in this area.

  17. Distribution of sea snakes in the Great Barrier Reef Marine Park: observations from 10 yrs of baited remote underwater video station (BRUVS) sampling

    Science.gov (United States)

    Udyawer, Vinay; Cappo, Mike; Simpfendorfer, Colin A.; Heupel, Michelle R.; Lukoschek, Vimoksalehi

    2014-09-01

    The distributions of three species of sea snake (olive sea snake: Aipysurus laevis, spine-bellied sea snake: Lapemis curtus, and ornate sea snake: Hydrophis ocellatus) were estimated over 14° of latitude within the Great Barrier Reef Marine Park (GBRMP) using data from baited remote underwater video stations (BRUVS). A total of 2,471 deployments of BRUVS were made in a range of locations, in sites open and closed to trawl fishing. Sightings of sea snakes were analysed alongside six spatial factors [depth, relative distance across (longitude) and along (latitude) the GBRMP, proximity to land, proximity to the nearest reef, and habitat complexity] to determine the factors that most strongly influenced the distribution and abundance of sea snakes. The results showed a strong latitudinal effect on the distribution of all three sea snake species, with the highest densities and diversities occurring in central and southern GBRMP locations, while the northern Great Barrier Reef was relatively depauperate in terms of both occurrence and diversity. Shallow inshore areas were identified as key habitats for A. laevis and L. curtus, whereas deeper offshore habitats were most important for H. ocellatus. No significant difference was found in the mean number of snakes sighted per hour between sites open and closed to trawling. There was a high degree of congruence in the distribution of sea snakes estimated from the BRUVS data and results from previous trawl and underwater visual surveys, demonstrating the utility of BRUVS to estimate distribution and relative abundance in these species of sea snake at broad spatial scales in a non-extractive manner.

  18. Why is it so hard to implement change? A qualitative examination of barriers and facilitators to distribution of naloxone for overdose prevention in a safety net environment.

    Science.gov (United States)

    Drainoni, Mari-Lynn; Koppelman, Elisa A; Feldman, James A; Walley, Alexander Y; Mitchell, Patricia M; Ellison, Jacqueline; Bernstein, Edward

    2016-10-18

    The increase in opioid overdose deaths has become a national public health crisis. Naloxone is an important tool in opioid overdose prevention. Distribution of nasal naloxone has been found to be a feasible, and effective intervention in community settings and may have potential high applicability in the emergency department, which is often the initial point of care for persons at high risk of overdose. One safety net hospital introduced an innovative policy to offer take-home nasal naloxone via a standing order to ensure distribution to patients at risk for overdose. The aims of this study were to examine acceptance and uptake of the policy and assess facilitators and barriers to implementation. After obtaining pre-post data on naloxone distribution, we conducted a qualitative study. The PARiHS framework steered development of the qualitative guide. We used theoretical sampling in order to include the range of types of emergency department staff (50 total). The constant comparative method was initially used to code the transcripts and identify themes; the themes that emerged from the coding were then mapped back to the evidence, context and facilitation constructs of the PARiHS framework. Acceptance of the policy was good but uptake was low. Primary themes related to facilitators included: real-world driven intervention with philosophical, clinician and leadership support; basic education and training efforts; availability of resources; and ability to leave the ED with the naloxone kit in hand. Barriers fell into five general categories: protocol and policy; workflow and logistical; patient-related; staff roles and responsibilities; and education and training. The actual implementation of a new innovation in healthcare delivery is largely driven by factors beyond acceptance. Despite support and resources, implementation was challenging, with low uptake. While the potential of this innovation is unknown, understanding the experience is important to improve uptake

  19. Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

    Science.gov (United States)

    Takahashi, Go; Akashi, Haruaki

    AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

  20. Improving hole injection and carrier distribution in InGaN light-emitting diodes by removing the electron blocking layer and including a unique last quantum barrier

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Liwen, E-mail: lwcheng@yzu.edu.cn; Chen, Haitao; Wu, Shudong [College of Physics Science and Technology & Institute of Optoelectronic Technology, Yangzhou University, Yangzhou 225002 (China)

    2015-08-28

    The effects of removing the AlGaN electron blocking layer (EBL), and using a last quantum barrier (LQB) with a unique design in conventional blue InGaN light-emitting diodes (LEDs), were investigated through simulations. Compared with the conventional LED design that contained a GaN LQB and an AlGaN EBL, the LED that contained an AlGaN LQB with a graded-composition and no EBL exhibited enhanced optical performance and less efficiency droop. This effect was caused by an enhanced electron confinement and hole injection efficiency. Furthermore, when the AlGaN LQB was replaced with a triangular graded-composition, the performance improved further and the efficiency droop was lowered. The simulation results indicated that the enhanced hole injection efficiency and uniform distribution of carriers observed in the quantum wells were caused by the smoothing and thinning of the potential barrier for the holes. This allowed a greater number of holes to tunnel into the quantum wells from the p-type regions in the proposed LED structure.

  1. Parallax adjustment for visual comfort enhancement using the effect of parallax distribution and cross talk in parallax-barrier autostereoscopic three-dimensional display

    Science.gov (United States)

    Kim, Donghyun; Lee, Hyoung; Kim, Sung-Kyu; Sohn, Kwanghoon

    2015-12-01

    Visual discomfort is a common problem in three-dimensional (3D) videos, and this issue is the subject of many current studies. Among the methods to overcome visual discomfort presented in current research, parallax adjustment methods provide little guidance in determining the condition for parallax control. We propose a parallax adjustment based on the effects of parallax distribution and cross talk on visual comfort, where the visual comfort level is used as the adjustment parameter, in parallax-barrier-type autostereoscopic 3D displays. We use the horizontal image shift method for parallax adjustment to enhance visual comfort. The speeded-up robust feature is used to estimate the parallax distribution of 3D sequences, and the required amount for parallax control is chosen based on the predefined effect of parallax distribution and cross talk on visual comfort. To evaluate the performance of the proposed method, we used commercial 3D equipment with various intrinsic cross-talk levels. Subjective tests were conducted at the fixed optimal viewing distance for each piece of equipment. The results show that comfortable videos were generated based on the proposed parallax adjustment method.

  2. The consequences of air flow on the distribution of aqueous species during dielectric barrier discharge treatment of thin water layers

    Science.gov (United States)

    Tian, Wei; Lietz, Amanda M.; Kushner, Mark J.

    2016-10-01

    The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) strongly depend on the integrated fluences of reactive species incident onto the tissue, which are determined by power, frequency and treatment time. The reactivity produced by such plasmas is often expected to be proportional to treatment time due to the accumulation of radicals in the liquid over the tissue. However, one of the typically uncontrolled parameters in DBD treatment of liquids and tissue is gas flow, which could affect the delivery of plasma produced radicals to the tissue. Gas flow can redistribute long-lived, plasma produced gas phase species prior to solvating in the liquid, while not greatly affecting the solvation of short-lived species. Gas flow can therefore potentially be a control mechanism for tailoring the fluences of reactive species to the tissue. In this paper, we report on a computational investigation of the consequences of gas flow on treatment of liquid layers covering tissue by atmospheric DBDs by up to 100 pulses. We found that gas flow (through residence time of the gas) can control the production of gas phase species requiring many collisions to form, such as reactive nitrogen species (RNS). The resulting solvation of the RNS in turn controls the production of aqueous species such as \\text{NO}\\text{3aq}- and \\text{ONOO}\\text{aq}- (aq denotes an aqueous species). With the exception of O3 and O3aq, reactive oxygen species (ROS) are less sensitive to gas flow, and so OHaq and H2O2aq, are determined primarily by discharge properties.

  3. Historical habitat barriers prevent ring-like genetic continuity throughout the distribution of threatened Alameda Striped Racers (Coluber lateralis euryxanthus)

    Science.gov (United States)

    Richmond, Jonathan Q.; Wood, Dustin A.; Swaim, Karen; Fisher, Robert N.; Vandergast, Amy

    2016-01-01

    We used microsatellites and mtDNA sequences to examine the mixed effects of geophysical, habitat, and contemporary urban barriers on the genetics of threatened Alameda Striped Racers (Coluber lateralis euryxanthus), a species with close ties to declining coastal scrub and chaparral habitat in the eastern San Francisco Bay area of California. We used cluster assignments to characterize population genetic structuring with respect to land management units and approximate Bayesian analysis to rank the ability of five alternative evolutionary hypotheses to explain the inferred structure. Then, we estimated rates of contemporary and historical migration among the major clusters and measured the fit of different historical migration models to better understand the formation of the current population structure. Our results reveal a ring-like pattern of historical connectivity around the Tri-Valley area of the East Bay (i.e., San Ramon, Amador, and Livermore valleys), with clusters largely corresponding to different management units. We found no evidence of continuous gene flow throughout the ring, however, and that the main gap in continuity is centered across the Livermore Valley. Historical migration models support higher rates of gene flow away from the terminal ends of the ring on the north and south sides of the Valley, compared with rates into those areas from western sites that border the interior San Francisco Bay. We attribute the break in ring-like connectivity to the presence of unsuitable habitat within the Livermore Valley that has been reinforced by 20th century urbanization, and the asymmetry in gene flow rates to spatial constraints on movement and east–west environmental gradients influenced by the proximity of the San Francisco Bay.

  4. Distribution and abundance of anadromous Sea Lamprey Spawners in a fragmented stream: Current status and potential range expansion following barrier removal

    Science.gov (United States)

    Zydlewski, Joseph; Gardner, Cory; Coghlan Jr., Stephen M.

    2012-01-01

    Dams fragment watersheds and prevent anadromous fishes from reaching historic spawning habitat. Sedgeunkedunk Stream, a small tributary to the Penobscot River (Maine), has been the focus of efforts to reestablish marine-freshwater connectivity and restore anadromous fishes via the removal of two barriers to fish migration. Currently, Petromyzon marinus (Sea Lamprey) is the only anadromous fish known to spawn successfully in the stream downstream of the lowermost dam. Here, we describe the distribution and abundance of a spawning population of Sea Lamprey in Sedgeunkedunk Stream, prior to and in anticipation of habitat increase after the completion of one barrier removal. In 2008, we estimated the abundance of Sea Lamprey and its nests using daily stream surveys and an open-population mark-recapture model. We captured 47 Sea Lamprey and implanted each with a PIT tag so that we could track movements and nest associations of individual fish. The spawning migration began on 18 June, and the last living individual was observed on 27 June. We located 31 nests, distributed from head-of-tide to the lowermost dam; no spawners or nests were observed in the tidally influenced zone or upstream of this dam. Mean longevity in the stream and the number of nests attended were correlated with arrival date; early migrants were alive longer and attended more nests than later migrants. Males were more likely to be observed away from a nest, or attending three or more nests, than were females, which attended usually one or two nests. We observed a negative association between nest abundance and substrate cover by fine sediment. Based on their observed movements in the system, and the extent of their habitat use, we anticipate that spawning Sea Lamprey will recolonize formerly inaccessible habitat after dam removals.

  5. Distribution of two species of sea snakes, Aipysurus laevis and Emydocephalus annulatus, in the southern Great Barrier Reef: metapopulation dynamics, marine protected areas and conservation

    Science.gov (United States)

    Lukoschek, V.; Heatwole, H.; Grech, A.; Burns, G.; Marsh, H.

    2007-06-01

    Aipysurus laevis and Emydocephalus annulatus typically occur in spatially discrete populations, characteristic of metapopulations; however, little is known about the factors influencing the spatial and temporal stability of populations or whether specific conservation strategies, such as networks of marine protected areas, will ensure the persistence of species. Classification tree analyses of 35 years of distribution data (90 reefs, surveyed 1-11 times) in the southern Great Barrier Reef (GBR) revealed that longitude was a major factor determining the status of A. laevis on reefs (present = 38, absent = 38 and changed = 14). Reef exposure and reef area were also important; however, these factors did not specifically account for the population fluctuations and the recent local extinctions of A. laevis in this region. There were no relationships between the status of E. annulatus (present = 16, absent = 68 and changed = 6) and spatial or physical variables. Moreover, prior protection status of reefs did not account for the distribution of either species. Biotic factors, such as habitat and prey availability and the distribution of predators, which may account for the observed patterns of distribution, are discussed. The potential for inter-population exchange among sea snake populations is poorly understood, as is the degree of protection that will be afforded to sea snakes by the recently implemented network of No-take areas in the GBR. Data from this study provide a baseline for evaluating the responses of A. laevis and E. annulatus populations to changes in biotic factors and the degree of protection afforded on reefs within an ecosystem network of No-take marine protected areas in the southern GBR.

  6. c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D.

    2013-01-01

    During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII–IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research. PMID:23169788

  7. c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution.

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D; Cheng, C Yan

    2013-01-15

    During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII-IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research.

  8. Density functional studies on wurtzite piezotronic transistors: influence of different semiconductors and metals on piezoelectric charge distribution and Schottky barrier.

    Science.gov (United States)

    Liu, Wei; Zhang, Aihua; Zhang, Yan; Wang, Zhong Lin

    2016-05-20

    The mechanical-electrical coupling properties of piezoelectric semiconductors endow these materials with novel device applications in microelectromechanical systems, sensors, human-computer interfaces, etc. When an applied strain is exerted on a piezoelectric semiconductor, piezoelectric charges are generated at the surface or interface of the semiconductor, which can be utilized to control the electronic transport characteristics. This is the fundamental working mechanism of piezotronic devices, called the piezotronic effect. In the present report, a series of piezotronic transistors composed of different electrode metals and semiconductors is examined using density functional theory calculation. It is found that the influence of semiconductors on the piezotronic effect is larger than the impact of metals, and GaN and CdS are promising candidates for piezotronic and piezo-phototronic devices, respectively. The width of the piezoelectric charge distribution obtained in the present study can be used as a parameter in classical finite-element-method based simulations, which provide guidance on designing high-performance piezotronic devices.

  9. Density functional studies on wurtzite piezotronic transistors: influence of different semiconductors and metals on piezoelectric charge distribution and Schottky barrier

    Science.gov (United States)

    Liu, Wei; Zhang, Aihua; Zhang, Yan; Wang, Zhong Lin

    2016-05-01

    The mechanical-electrical coupling properties of piezoelectric semiconductors endow these materials with novel device applications in microelectromechanical systems, sensors, human-computer interfaces, etc. When an applied strain is exerted on a piezoelectric semiconductor, piezoelectric charges are generated at the surface or interface of the semiconductor, which can be utilized to control the electronic transport characteristics. This is the fundamental working mechanism of piezotronic devices, called the piezotronic effect. In the present report, a series of piezotronic transistors composed of different electrode metals and semiconductors is examined using density functional theory calculation. It is found that the influence of semiconductors on the piezotronic effect is larger than the impact of metals, and GaN and CdS are promising candidates for piezotronic and piezo-phototronic devices, respectively. The width of the piezoelectric charge distribution obtained in the present study can be used as a parameter in classical finite-element-method based simulations, which provide guidance on designing high-performance piezotronic devices.

  10. Ecology of the ciguatera causing dinoflagellates from the Northern Great Barrier Reef: changes in community distribution and coastal eutrophication.

    Science.gov (United States)

    Skinner, Mark P; Lewis, Richard J; Morton, Steve

    2013-12-15

    Ciguatera fish poisoning (CFP) is known to be caused by the ciguatoxins from the dinoflagellate genus Gambierdiscus, however, there is the potential for other toxins such as okadaic acid and dinophysistoxins from the genus Prorocentrum, and palytoxin from the genus Ostreopsis, to contaminate seafood. These genera may also be indicators of ecosystem health and potentially impact on coral reef ecosystems and the role they may play in the succession of coral to macroalgae dominated reefs has not been researched. Sixteen GBR field sites spanning inshore, mid-lagoon and outer lagoon (offshore) regions were studied. Samples were collected from September 2006 to December 2007 and abundance of benthic dinoflagellates on different host macroalgae and concentration of nutrients present in the water column were determined. The maximum abundance of Prorocentrum, Ostreopsis and Gambierdiscus found was 112, 793 and 50 cells per gram wet weight of host macroalgae, respectively. The average level of Dissolved Inorganic Nitrogen (DIN) in the water column across all sites (0.03 mg/L) was found to be more than double the threshold critical value (0.013 mg/L) for healthy coral reefs. Compared to a previous study 1984, there is evidence of a major shift in the distribution and abundance of these dinoflagellates. Inshore reefs have either of Prorocentrum (as at Green Island) or Ostreopsis (as at Magnetic Island) dominating the macroalgal surface niche which was once dominated by Gambierdiscus, whilst at offshore regions Gambierdiscus is still dominant. This succession may be linked to the ongoing eutrophication of the GBR lagoon and have consequences for the sources of toxins for ongoing cases of ciguatera.

  11. The distribution of henipaviruses in Southeast Asia and Australasia: is Wallace's line a barrier to Nipah virus?

    Directory of Open Access Journals (Sweden)

    Andrew C Breed

    Full Text Available Nipah virus (NiV (Genus Henipavirus is a recently emerged zoonotic virus that causes severe disease in humans and has been found in bats of the genus Pteropus. Whilst NiV has not been detected in Australia, evidence for NiV-infection has been found in pteropid bats in some of Australia's closest neighbours. The aim of this study was to determine the occurrence of henipaviruses in fruit bat (Family Pteropodidae populations to the north of Australia. In particular we tested the hypothesis that Nipah virus is restricted to west of Wallace's Line. Fruit bats from Australia, Papua New Guinea, East Timor and Indonesia were tested for the presence of antibodies to Hendra virus (HeV and Nipah virus, and tested for the presence of HeV, NiV or henipavirus RNA by PCR. Evidence was found for the presence of Nipah virus in both Pteropus vampyrus and Rousettus amplexicaudatus populations from East Timor. Serology and PCR also suggested the presence of a henipavirus that was neither HeV nor NiV in Pteropus alecto and Acerodon celebensis. The results demonstrate the presence of NiV in the fruit bat populations on the eastern side of Wallace's Line and within 500 km of Australia. They indicate the presence of non-NiV, non-HeV henipaviruses in fruit bat populations of Sulawesi and Sumba and possibly in Papua New Guinea. It appears that NiV is present where P. vampyrus occurs, such as in the fruit bat populations of Timor, but where this bat species is absent other henipaviruses may be present, as on Sulawesi and Sumba. Evidence was obtained for the presence henipaviruses in the non-Pteropid species R. amplexicaudatus and in A. celebensis. The findings of this work fill some gaps in knowledge in geographical and species distribution of henipaviruses in Australasia which will contribute to planning of risk management and surveillance activities.

  12. Visualizing changes in electron distribution in coupled chains of cytochrome bc1 by modifying barrier for electron transfer between the FeS cluster and heme c1

    Science.gov (United States)

    Cieluch, Ewelina; Pietryga, Krzysztof; Sarewicz, Marcin; Osyczka, Artur

    2010-01-01

    Cytochrome c1 of Rhodobacter (Rba.) species provides a series of mutants which change barriers for electron transfer through the cofactor chains of cytochrome bc1 by modifying heme c1 redox midpoint potential. Analysis of post-flash electron distribution in such systems can provide useful information about the contribution of individual reactions to the overall electron flow. In Rba. capsulatus, the non-functional low-potential forms of cytochrome c1 which are devoid of the disulfide bond naturally present in this protein revert spontaneously by introducing a second-site suppression (mutation A181T) that brings the potential of heme c1 back to the functionally high levels, yet maintains it some 100 mV lower from the native value. Here we report that the disulfide and the mutation A181T can coexist in one protein but the mutation exerts a dominant effect on the redox properties of heme c1 and the potential remains at the same lower value as in the disulfide-free form. This establishes effective means to modify a barrier for electron transfer between the FeS cluster and heme c1 without breaking disulfide. A comparison of the flash-induced electron transfers in native and mutated cytochrome bc1 revealed significant differences in the post-flash equilibrium distribution of electrons only when the connection of the chains with the quinone pool was interrupted at the level of either of the catalytic sites by the use of specific inhibitors, antimycin or myxothiazol. In the non-inhibited system no such differences were observed. We explain the results using a kinetic model in which a shift in the equilibrium of one reaction influences the equilibrium of all remaining reactions in the cofactor chains. It follows a rather simple description in which the direction of electron flow through the coupled chains of cytochrome bc1 exclusively depends on the rates of all reversible partial reactions, including the Q/QH2 exchange rate to/from the catalytic sites. PMID:19917265

  13. The study of the (α, α'f) reaction at 120 MeV on 232Th and 238U (II) : Fission barrier properties deduced from fission probabilities and angular distributions

    NARCIS (Netherlands)

    Plicht, J. van der; Harakeh, M.N.; van der Woude, Adriaan; David, P.; Debrus, J.; Janszen, H.; Schulze, J.

    1981-01-01

    The fission probabilities and angular distributions of the fission fragments for the (α, α'f) reaction on 232Th and 238U at a bombarding energy of 120 MeV have been measured from about 4 to 14 MeV excitation energy. Evidence for sub-barrier resonances has been found, the negative parity ones occurri

  14. Double exponential I-V characteristics and double Gaussian distribution of barrier heights in (Au/Ti)/Al2O3/ n-GaAs (MIS)-type Schottky barrier diodes in wide temperature range

    Science.gov (United States)

    Güçlü, Çiğdem Ş.; Özdemir, Ahmet Faruk; Altindal, Şemsettin

    2016-12-01

    In this study, current conduction mechanisms of the sample (Au/Ti)/Al2O3/ n-GaAs were investigated in detail using current-voltage (I-V) measurements in the temperature range of 80-380 K. The semilogarithmic I-V plots reveal two distinct linear regions with different slopes between 0.07-0.30 and 0.30-0.69 V which are called as Region I (RI) and Region II (RII), respectively. The ideality factor ( n) and zero-bias barrier height (Φ_{{bo}}) were found to be strong functions of temperature and voltage. In both regions, as the temperature increases, Φ_{{bo}} increases, whereas the value of n decreases. The high value of n at low temperatures is an evidence of deviation from thermionic emission, and it cannot be explained solely by tunneling mechanism, the existence of surface states and interfacial layer. Therefore, the Φ_{{bo}} versus q/kT plots were drawn for two linear regions of lnI-V plots, and these plots also revealed two distinct linear regions with different slopes between two temperature regions of 80-170 and 200-380 K which are called as low- and high-temperature range (LTR and HTR), respectively. Such behavior of these plots confirmed the existence of double Gaussian distribution (DGD) in the samples which in turn has mean barrier heights bar{Φ}_{{bo}} and standard deviations ( σ s). These values were obtained from the intercept and slope of these plots as 0.38 eV and 0.061 V for LTR and as 0.88 eV and 0.142 V for HTR (in RI), whereas they were obtained as 0.37 eV and 0.061 V for LTR and as 0.92 eV and 0.148 V for HTR (in RII), respectively. Thus, the modified ln( I s/ T 2)- q 2 σ s 2 /2 k 2 T 2 versus q/ kT plots were drawn, and the values of (bar{Φ}_{{bo}}) and effective Richardson constant ( A *) were extracted from the intercept and slope of these plots as 0.39 eV and 7.07 A/cm2 K2 for LTR and as 0.92 eV and 8.158 A/cm2 K2 for HTR (in RI), whereas they were extracted as 0.38 eV and 7.92 A/cm2 K2 for LTR and as 0.94 eV and 4.66 A/cm2 K2 for HTR

  15. U-Th age distribution of coral fragments from multiple rubble ridges within the Frankland Islands, Great Barrier Reef: Implications for past storminess history

    Science.gov (United States)

    Liu, Entao; Zhao, Jian-xin; Feng, Yue-xing; Leonard, Nicole D.; Clark, Tara R.; Roff, George

    2016-07-01

    Prograded coral rubble ridges have been widely used as archives for reconstructing long-term storm or storminess history. Chronologies of ridge systems in previous studies are often based on a limited number of low-resolution radiocarbon or optically-stimulated luminescence (OSL) ages per ridge (usually only one age per ridge), which carry intrinsic age uncertainties and make interpretation of storm histories problematic. To test the fidelity of storm ridges as palaeo-storm archives, we used high-precision U-Th dating to examine whether different samples from a single ridge are temporally constrained. We surveyed three transects of ridge systems from two continental islands (Normanby Island and High Island) within the Frankland Islands, Great Barrier Reef (GBR), and obtained 96 U-Th dates from coral rubble samples collected from within and between different ridges. Our results revealed significant differences in age ranges between the two islands. The steeper and more defined rubble ridges present on Normanby Island revealed that the majority of U-Th ages (over 60%) from a single ridge clustered within a narrow age range (∼100 years). By contrast, the lower and less defined ridges on High Island, which were more likely formed during both storm and non-storm high-energy events, revealed significant scatter in age distribution (>>200 years) with no notable clustering. The narrower age ranges obtained from the steeper and more defined rubble ridges suggest that previous approaches of using either limited samples from a single ridge or low-precision dating methods to establish chronologies are generally valid at centennial to millennial timescales, although caution must be taken to use such approaches for storm history reconstruction on shorter timescales (e.g. decadal). The correlation between U-Th mortality ages of coral rubble and historical stormy periods highlights the possibility of using coral rubble age distribution from rubble ridges to reconstruct the long

  16. Development of Innovating Materials for Distributing Mixtures of Hydrogen and Natural Gas. Study of the Barrier Properties and Durability of Polymer Pipes

    Directory of Open Access Journals (Sweden)

    Klopffer Marie-Hélène

    2015-02-01

    Full Text Available With the growing place taken by hydrogen, a question still remains about its delivery and transport from the production site to the end user by employing the existing extensive natural gas pipelines. Indeed, the key challenge is the significant H2 permeation through polymer infrastructures (PolyEthylene (PE pipes, components such as connecting parts. This high flow rate of H2 through PE has to be taken into account for safety and economic requirements. A 3-year project was launched, the aim of which was to develop and assess material solutions to cope with present problems for hydrogen gas distribution and to sustain higher pressure compared to classical high density polyethylene pipe. This project investigated pure hydrogen gas and mixtures with natural gas (20% of CH4 and 80% of H2 in pipelines with the aim to select engineering polymers which are more innovative than polyethylene and show outstanding properties, in terms of permeation, basic mechanical tests but also more specific characterizations such as long term ageing and behaviour. The adequate benches, equipments and scientific approach for materials testing had been developed and validated. In this context, the paper will focus on the evaluation of the barrier properties of 3 polymers (PE, PA11 and PAHM. Experiments were performed for pure H2 and CH4 and also in the presence of mixtures of hydrogen and natural gas in order to study the possible mixing effects of gases. It will report some round-robin tests that have been carried out. Secondly, by comparing data obtained on film, polymer membrane and on pipe section, the influence of the polymer processing will be studied. Innovative multilayers systems will be proposed and compared on the basis of the results obtained on monolayer systems. Finally, the evolution of the transport properties of the studied polymers with an ageing under representative service conditions will be discussed.

  17. Heavy-ion fusion and scattering with Skyrme energy density functional

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In our recent studies,an empirical barrier distribution was proposed for a unified description of the fusion cross sections of light and medium-heavy fusion systems,the capture cross sections of the reactions leading to superheavy nuclei,and the large-angle quasi-elastic scattering cross sections based on the Skyrme energy-density functional approach.In this paper,we first give a brief review of these results.Then,by examining the barrier distributions in detail,we find that the fusion cross sections depend more strongly on the shape of the left side of the barrier distribution while the quasi-elastic scattering cross sections depend more strongly on the right side.Furthermore,by combining these studies and the HIVAP calculations for the survival probability,the formation probability of the compound nucleus is deduced from the measured evaporation residue cross sections for "cold" and "hot" fusion reactions.

  18. Differential distribution of tight junction proteins suggests a role for tanycytes in blood-hypothalamus barrier regulation in the adult mouse brain.

    Science.gov (United States)

    Mullier, Amandine; Bouret, Sebastien G; Prevot, Vincent; Dehouck, Bénédicte

    2010-04-01

    The median eminence is one of the seven so-called circumventricular organs. It is located in the basal hypothalamus, ventral to the third ventricle and adjacent to the arcuate nucleus. This structure characteristically contains a rich capillary plexus and features a fenestrated endothelium, making it a direct target of blood-borne molecules. The median eminence also contains highly specialized ependymal cells called tanycytes, which line the floor of the third ventricle. It has been hypothesized that one of the functions of these cells is to create a barrier that prevents substances in the portal capillary spaces from entering the brain. In this paper, we utilize immunohistochemistry to study the expression of tight junction proteins in the cells that compose the median eminence in adult mice. Our results indicate that tanycytes of the median eminence express occludin, ZO-1, and claudin 1 and 5, but not claudin 3. Remarkably, these molecules are organized as a continuous belt around the cell bodies of the tanycytes that line the ventral part of the third ventricle. In contrast, the tanycytes at the periphery of the arcuate nucleus do not express claudin 1 and instead exhibit a disorganized expression pattern of occludin, ZO-1, and claudin 5. Consistent with these observations, permeability studies using peripheral or central injections of Evans blue dye show that only the tanycytes of the median eminence are joined at their apices by functional tight junctions, whereas tanycytes located at the level of the arcuate nucleus form a permeable layer. In conclusion, this study reveals a unique expression pattern of tight junction proteins in hypothalamic tanycytes, which yields new insights into their barrier properties.

  19. Surface Barrier Models of ZnO

    Institute of Scientific and Technical Information of China (English)

    MA Yong; WANG Wan-lu; LIAO Ke-jun; KONG Chun-yang

    2004-01-01

    For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.

  20. Measurements of Sub-Barrier Transfer Yields in SULFUR-32 + NIOBIUM-93, MOLYBDENUM(98,100) Reactions at 180 Degrees

    Science.gov (United States)

    Roberts, Roland Blaine

    1994-01-01

    The Rochester RMS was used to measure excitation functions for 180^circ sub -barrier one- and two-neutron pickup reactions for E _{rm lab} final states were not identified. The RMS technique was chosen for its self-normalizing property which makes obtaining absolute cross sections straightforward. The distorted-wave Born-approximation (DWBA) computer code scPTOLEMY was used to obtain quantal predictions of the one-neutron pickup yields. The calculations were performed for several final states and summed (using the appropriate spectroscopic factors) to estimate the total quasi-elastic transfer yield. P scTOLEMY over-predicted the yield in each system by a factor of 2-3. Since DWBA calculations for heavy-ion reactions are known to have difficulty reproducing experimentally measured yields within a factor of two, this discrepancy is not surprising. Although the absolute yields were not reproduced by the calculations, the shape of the excitation function is well reproduced. No calculations were performed for two-neutron transfer due to the lack of reliable spectroscopic factors. The transfer probabilities are obtained directly from these measurements. Distances of closest approach were calculated using a proximity potential. The slopes of transfer probability vs distance of closest approach are in good agreement with the predictions obtained from semi-classical theory using binding energies, indicating the absence of a "slope anomaly." This is consistent with the prediction that diffractive effects, which may distort the measured slope, are minimized at backward angles and sub-barrier energies--the precise conditions under which these measurements were performed. Angle-integrated transfer cross sections were derived from the measured transfer probabilities by assuming the ions follow Rutherford trajectories. These derived yields are consistent with the hypothesis that fusion enhancements in previously measured fusion yields for the ^ {32}S + ^{98,100} Mo systems are

  1. Clay mineralogy, grain size distribution and their correlations with trace metals in the salt marsh sediments of the Skallingen barrier spit, Danish Wadden Sea

    DEFF Research Database (Denmark)

    He, Changling; Bartholdy, Jesper; Christiansen, Christian

    2012-01-01

    metals. The clay assembly of the sediment consists of illite, kaolinite and much less chlorite and smectite. The major clay minerals of illite, kaolinite as well as chlorite correlate very poorly with all the trace metals investigated, due probably to the weak competing strength of these clays compared...... with the other adsorbents and to low availability of the mobile trace metals in the system. Correlation between trace metals and clay minerals may therefore be used as an indicator in environmental assessment. Fine grain fractions of the sediment increased markedly after salt marsh invasion in about 1931......To understand the behavior of trace metals in the salt marsh at Skallingen, Danish Wadden Sea, we investigated a profile from surface to 25 cm depth of the salt marsh sediment, focusing primarily on clay mineralogy and grain size distribution of the sediments and their relationship with trace...

  2. Reaction 48Ca+208Pb: the capture-fission cross-sections and the mass-energy distributions of fragments above and deep below the Coulomb barrier

    CERN Document Server

    Prokhorova, E V; Itkis, M G; Kondratev, N A; Kozulin, E M; Krupa, L; Oganessian, Yu T; Pashkevich, V V; Pokrovsky, I V; Rusanov, A Ya; Oganessian, Yu.Ts.

    2003-01-01

    The capture-fission cross-sections in an energy range of 206-242 MeV of 48Ca-projectiles and mass-energy distributions (MEDs) of reaction products in an energy range of 211-242 MeV have been measured in the 48Ca+208Pb reaction using the double-arm time-of-flight spectrometer CORSET. The MEDs of fragments for heated fission were shown to consist of two components. One component, which is due to classical fusion-fission, is associated with the symmetric fission of the 256No compound nucleus. The other component, which appears as ''shoulders'', is associated with the quasi-fission process and can be named ''quasi-fission shoulders''. Those quasi-fission shoulders enclose light fragments whose masses are 60-90 a.m.u. The total kinetic energy (TKE) of the fragments that belong to the shoulders is higher than the value expected for a classical fusion-fission process. We have come to the conclusion that in quasi-fission, spherical shells with Z=28 and N=50 play a great role. It has also been demonstrated that the pr...

  3. Nanomedicine Faces Barriers

    Directory of Open Access Journals (Sweden)

    Paul Debbage

    2010-10-01

    Full Text Available Targeted nanoparticles have the potential to improve drug delivery efficiencies by more than two orders of magnitude, from the ~ 0.1% which is common today. Most pharmacologically agents on the market today are small drug molecules, which diffuse across the body’s blood-tissue barriers and distribute not only into the lesion, but into almost all organs. Drug actions in the non-lesion organs are an inescapable part of the drug delivery principle, causing “side-effects” which limit the maximally tolerable doses and result in inadequate therapy of many lesions. Nanoparticles only cross barriers by design, so side-effects are not built into their mode of operation. Delivery rates of almost 90% have been reported. This review examines the significance of these statements and checks how far they need qualification. What type of targeting is required? Is a single targeting sufficient? What new types of clinical challenge, such as immunogenicity, might attend the use of targeted nanoparticles?

  4. Dynamic changes in the distribution and time course of blood-brain barrier-permeative nitroxides in the mouse head with EPR imaging: visualization of blood flow in a mouse model of ischemia.

    Science.gov (United States)

    Emoto, Miho C; Sato-Akaba, Hideo; Hirata, Hiroshi; Fujii, Hirotada G

    2014-09-01

    Electron paramagnetic resonance (EPR) imaging using nitroxides as redox-sensitive probes is a powerful, noninvasive method that can be used under various physiological conditions to visualize changes in redox status that result from oxidative damage. Two blood-brain barrier-permeative nitroxides, 3-hydroxymethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (HMP) and 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-yloxy (MCP), have been widely used as redox-sensitive probes in the brains of small animals, but their in vivo distribution and properties have not yet been analyzed in detail. In this study, a custom-made continuous-wave three-dimensional (3D) EPR imager was used to obtain 3D EPR images of mouse heads using MCP or HMP. This EPR imager made it possible to take 3D EPR images reconstructed from data from 181 projections acquired every 60s. Using this improved EPR imager and magnetic resonance imaging, the distribution and reduction time courses of HMP and MCP were examined in mouse heads. EPR images of living mice revealed that HMP and MCP have different distributions and different time courses for entering the brain. Based on the pharmacokinetics of the reduction reactions of HMP and MCP in the mouse head, the half-lives of HMP and MCP were clearly and accurately mapped pixel by pixel. An ischemic mouse model was prepared, and the half-life of MCP was mapped in the mouse head. Compared to the half-life in control mice, the half-life of MCP in the ischemic model mouse brain was significantly increased, suggesting a shift in the redox balance. This in vivo EPR imaging method using BBB-permeative MCP is a useful noninvasive method for assessing changes in the redox status in mouse brains under oxidative stress.

  5. Smart parking barrier

    KAUST Repository

    Alharbi, Abdulrazaq M.

    2016-05-06

    Various methods and systems are provided for smart parking barriers. In one example, among others, a smart parking barrier system includes a movable parking barrier located at one end of a parking space, a barrier drive configured to control positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking space and a second position that allows access to the parking space. The parking controller can initiate movement of the movable parking barrier in response to a positive identification of an individual allowed to use the parking space. The parking controller can identify the individual through, e.g., a RFID tag, a mobile device (e.g., a remote control, smartphone, tablet, etc.), an access card, biometric information, or other appropriate identifier.

  6. Motility analysis of circularly swimming bull spermatozoa by quasi-elastic light scattering and cinematography.

    Science.gov (United States)

    Craig, T; Hallett, F R; Nickel, B

    1982-04-01

    The Rayleigh-Gans-Debye approximation is used to predict the electric field autocorrelation functions of light scattered from circularly swimming bull spermatozoa. Using parameters determined from cinematography and modeling the cells as coated ellipsoids of semiaxes a = 0.5 micrometers, b = 2.3 micrometers, and c = 9.0 micrometers, we were able to obtain model spectra that mimic the data exactly. A coat is found to be a necessary attribute of the particle. It is also clear that these model functions at 15 degrees may be represented by the relatively simple function used before by Hallett et al. (1978) to fit data from circularly swimming cells, thus giving some physical meaning to these functional shapes. Because of this agreement the half-widths of experimental functions can now be interpreted in terms of an oscillatory frequency for the movement of the circularly swimming cell. The cinematographic results show a trend to chaotic behavior as the temperature of the sample is increased, with concomitant decrease in overall efficiency. This is manifested by a decrease in oscillatory frequency and translational speed.

  7. Is simultaneous $y$ and $\\xi$--scaling in the quasi-elastic region accidental?

    CERN Document Server

    Day, D

    2004-01-01

    We study the $y$ and $\\xi$--scaling of the nuclear response at large momentum transfer in order to understand how scaling based on very different descriptions of the elementary interaction can occur simultaneously. We find that the approximate validity of $\\xi$-scaling at low energy loss arises from the coincidental behavior of the quasielastic and deep inelastic cross sections.

  8. Simulating moist convection with a quasi-elastic sigma coordinate model

    CSIR Research Space (South Africa)

    Bopape, Mary-Jane M

    2012-10-01

    Full Text Available .kashan.co.za] The amount of rainfall that reached the surface is the same for the PURDUE- LIN1 and SBU-YLIN schemes, and it is smaller in the PURDUE-LIN2 simulations (Figure 3). This shows that graupel is effective in producing more rainfall that snow, when neither... Research (CSIR) and University of Pretoria in South Africa. The PURDUE-LIN (Sun and Chen, 2002) and SBU-YLIN (Lin and Colle, 2011) microphysics schemes obtained from the National Centre for Atmospheric research (NCAR) Weather Research and Forecasting...

  9. Quasi-elastic neutron scattering studies on dynamics of water confined in nanoporous copper rubeanate hydrates.

    Science.gov (United States)

    Yamada, Takeshi; Yonamine, Ryo; Yamada, Teppei; Kitagawa, Hiroshi; Tyagi, Madhusudan; Nagao, Michihiro; Yamamuro, Osamu

    2011-11-24

    We have investigated the mechanism of the first order transition and proton conductivity in copper rubeanate hydrates from microscopic and dynamical points of view. Three different types of neutron spectrometer-time-of-flight, backscattering, and neutron spin echo-were used to cover a wide dynamic range (1 ps to 100 ns). We found that the water molecules adsorbed in the pore are divided into "free water" having diffusion coefficients similar to those of bulk water at room temperature and "condensed water" which is about 10 times slower than bulk water owing to the interaction with the pore wall. The hydrogen atoms in the pore wall exhibited no relaxation within the measured time scales. The free water has, in the framework of the jump-diffusion model, smaller activation energy, longer residence time, and longer jump distance than bulk water. The neutron spin echo measurement revealed that the first order transition is a kind of liquid-liquid transition at which the free water is condensed on the pore surface in the low temperature phase. On cooling the condensed water, the relaxation time starts to deviate from the VFT equation around 200 K as previously observed in the water confined in nanoporous silicates. The free water plays an important role as the proton carrier but the proton conductivity is mainly governed by the number of protons provided into the adsorbed water from the pore wall.

  10. Coherent Dynamics of meta-Toluidine Investigated by QuasiElastic Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Faraone, Antonio [National Institute of Standards and Technology (NIST); Hong, Kunlun [ORNL; Kneller, Larry [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Ohl, Michael E [ORNL; Copley, John R. D. [National Institute of Standards and Technology (NIST), Gaithersburg, MD

    2012-01-01

    The coherent dynamics of a typical fragile glass former, meta-toluidine, was investigated at the molecular level using quasielastic neutron scattering, with time-of-flight and neutron spin echo spectrometers. It is well known that the static structure factor of meta-toluidine shows a prepeak originating from clustering of the molecules through hydrogen bonding between the amine groups. The dynamics of meta-toluidine was measured for several values of the wavevector transfer Q, which is equivalent to an inverse length scale, in a range encompassing the prepeak and the structure factor peak. Data were collected in the temperature range corresponding to the liquid and supercooled states, down to the glass transition. At least two dynamical processes were identified. This paper focuses on the slowest relaxation process in the system, the {alpha}-relaxation, which was found to scale with the macroscopic shear viscosity at all the investigated Q values. No evidence of 'de Gennes' narrowing associated with the prepeak was observed, in contrast with what happens at the Q value corresponding to the interparticle distance. Moreover, using partially deuterated samples, the dynamics of the clusters was found to be correlated to the single-particle dynamics of the meta-toluidine molecules.

  11. Quasi-elastic scattering, RPA, 2p2h and neutrino--energy reconstruction

    CERN Document Server

    Nieves, J; Sanchez, F; Vacas, M J Vicente

    2013-01-01

    We discuss some nuclear effects, RPA correlations and 2p2h (multinucleon) mechanisms, on charged-current neutrino-nucleus reactions that do not produce a pion in the final state. We study a wide range of neutrino energies, from few hundreds of MeV up to 10 GeV. We also examine the influence of 2p2h mechanisms on the neutrino energy reconstruction.

  12. Production of Z(0) bosons in elastic and quasi-elastic ep collisions at HERA

    NARCIS (Netherlands)

    Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartosik, N.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bold, T.; Bondarenko, K.; Boos, E. G.; Borras, K.; Boscherini, D.; Brock, I.; Brownson, E.; Brugnera, R.; Bruemmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A. M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, E.; del Peso, J.; Dementiev, R. K.; De Pasquale, S.; Derrick, M.; Devenish, R. C. E.; Dobur, D.; Dolgoshein, B. A.; Dolinska, G.; Doyle, A. T.; Drugakov, V.; Durkin, L. S.; Dusini, S.; Eisenberg, Y.; Ermolov, P. F.; Eskreys, A.; Fazio, S.; Ferrando, J.; Ferrero, M. I.; Figiel, J.; Foster, B.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gizhko, A.; Gladilin, L. K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Goettlicher, P.; Grabowska-Bold, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Guzik, M.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J. C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Huettmann, A.; Ibrahim, Z. A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H. -P; Januschek, F.; Jones, T. W.; Juengst, M.; Kadenko, I.; Kahle, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I. I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L. A.; Kim, J. Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Kondrashova, N.; Kononenko, O.; Kooijman, P.; Korol, Ie.; Korzhavina, I. A.; Kotanski, A.; Koetz, U.; Kowalski, H.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B. B.; Libov, V.; Limentani, S.; Ling, T. Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Loehr, B.; Lohrmann, E.; Long, K. R.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Mastroberardino, A.; Mattingly, M. C. K.; Melzer-Pellmann, I. -A.; Mergelmeyer, S.; Miglioranzi, S.; Idris, F. Mohamad; Monaco, V.; Montanari, A.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nigro, A.; Ning, Y.; Nobe, T.; Notz, D.; Nowak, R. J.; Nuncio-Quiroz, A. E.; Oh, B. Y.; Okazaki, N.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Pawlak, J. M.; Pawlik, B.; Pelfer, P. G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N. S.; Polini, A.; Proskuryakov, A. S.; Przybycien, M.; Raval, A.; Reeder, D. D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y. D.; Robertson, A.; Roloff, P.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Samson, U.; Sartorelli, G.; Savin, A. A.; Saxon, D. H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W. B.; Schneekloth, U.; Schoenberg, V.; Schoerner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L. M.; Shehzadi, R.; Singh, I.; Skillicorn, I. O.; Slominski, W.; Smith, W. H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stefaniuk, N.; Stern, A.; Stewart, T. P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A. D.; Tassi, E.; Terron, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomaszewska, J.; Trusov, V.; Tsurugai, T.; Turcato, M.; Turkot, O.; Tymieniecka, T.; Vazquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N. N.; Walczak, R.; Abdullah, W. A. T. Wan; Whitmore, J. J.; Wichmann, K.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yaguees-Molina, A. G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Zabiegalov, O.; Zarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B. O.; Zhmak, N.; Zichichi, A.; Zolkapli, Z.; Zotkin, D. S.

    2013-01-01

    The production of Z(0) bosons in the reaction ep -> eZ(0)p((*)), where p((*)) stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb(-1) of int

  13. Quasi-elastic reactions: an interplay of reaction dynamics and nuclear structure

    Directory of Open Access Journals (Sweden)

    Recchia F.

    2011-10-01

    Full Text Available Multinucleon transfer reactions have been investigated in 40Ar+208Pb with the Prisma+Clara set-up. The experimental differential cross sections of different neutron transfer channels have been obtained at three different angular settings taking into account the transmission through the spectrometer. The experimental yields of the excited states have been determined via particle-γ coincidences. In odd Ar isotopes, we reported a signif cant population of 11/2− states, reached via neutron transfer. Their structure matches a stretched conf guration of the valence neutron coupled to vibration quanta.

  14. Production of Z0 bosons in elastic and quasi-elastic ep collisions at HERA

    CERN Document Server

    Abramowicz, H; Adamczyk, L; Adamus, M; Aggarwal, R; Antonelli, S; Antonioli, P; Antonov, A; Arneodo, M; Arslan, O; Aushev, V; Aushev, Y; Bachynska, O; Bamberger, A; Barakbaev, A N; Barbagli, G; Bari, G; Barreiro, F; Bartosik, N; Bartsch, D; Basile, M; Behnke, O; Behr, J; Behrens, U; Bellagamba, L; Bertolin, A; Bhadra, S; Bindi, M; Blohm, C; Bokhonov, V; Bołd, T; Bondarenko, K; Boos, E G; Borras, K; Boscherini, D; Bot, D; Brock, I; Brownson, E; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Brzozowska, B; Bussey, P J; Bylsma, B; Caldwell, A; Capua, M; Carlin, R; Catterall, C D; Chekanov, S; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cifarelli, L; Cindolo, F; Contin, A; Cooper-Sarkar, A M; Coppola, N; Corradi, M; Corriveau, F; Costa, M; D'Agostini, G; Corso, F Dal; del Peso, J; Dementiev, R K; De Pasquale, S; Derrick, M; Devenish, R C E; Dobur, D; Dolgoshein, B A; Dolinska, G; Doyle, A T; Drugakov, V; Durkin, L S; Dusini, S; Eisenberg, Y; Ermolov, P F; Eskreys, A; Fang, S; Fazio, S; Ferrando, J; Ferrero, M I; Figiel, J; Foster, B; Gach, G; Galas, A; Gallo, E; Garfagnini, A; Geiser, A; Gialas, I; Gizhko, A; Gladilin, L K; Gladkov, D; Glasman, C; Gogota, O; Golubkov, Yu A; Göttlicher, P; Grabowska-Bołd, I; Grebenyuk, J; Gregor, I; Grigorescu, G; Grzelak, G; Gueta, O; Guzik, M; Gwenlan, C; Haas, T; Hain, W; Hamatsu, R; Hart, J C; Hartmann, H; Hartner, G; Hilger, E; Hochman, D; Hori, R; Hüttmann, A; Ibrahim, Z A; Iga, Y; Ingbir, R; Ishitsuka, M; Jakob, H -P; Januschek, F; Jones, T W; Jüngst, M; Kadenko, I; Kahle, B; Kananov, S; Kanno, T; Karshon, U; Karstens, F; Katkov, I I; Kaur, M; Kaur, P; Keramidas, A; Khein, L A; Kim, J Y; Kisielewska, D; Kitamura, S; Klanner, R; Klein, U; Koffeman, E; Kondrashova, N; Kononenko, O; Kooijman, P; Korol, Ie; Korzhavina, I A; Kotański, A; Kötz, U; Kowalski, H; Kuprash, O; Kuze, M; Lee, A; Levchenko, B B; Levy, A; Libov, V; Limentani, S; Ling, T Y; Lisovyi, M; Lobodzinska, E; Lohmann, W; Löhr, B; Lohrmann, E; Long, K R; Longhin, A; Lontkovskyi, D; Lukina, O Yu; Maeda, J; Magill, S; Makarenko, I; Malka, J; Mankel, R; Margotti, A; Marini, G; Martin, J F; Mastroberardino, A; Mattingly, M C K; Melzer-Pellmann, I -A; Mergelmeyer, S; Miglioranzi, S; Idris, F Mohamad; Monaco, V; Montanari, A; Morris, J D; Mujkic, K; Musgrave, B; Nagano, K; Namsoo, T; Nania, R; Nigro, A; Ning, Y; Nobe, T; Notz, D; Nowak, R J; Nuncio-Quiroz, A E; Oh, B Y; Okazaki, N; Olkiewicz, K; Onishchuk, Yu; Papageorgiu, K; Parenti, A; Paul, E; Pawlak, J M; Pawlik, B; Pelfer, P G; Pellegrino, A; Perlański, W; Perrey, H; Piotrzkowski, K; Pluciński, P; Pokrovskiy, N S; Polini, A; Proskuryakov, A S; Przybycień, M; Raval, A; Reeder, D D; Reisert, B; Ren, Z; Repond, J; Ri, Y D; Robertson, A; Roloff, P; Rubinsky, I; Ruspa, M; Sacchi, R; Samson, U; Sartorelli, G; Savin, A A; Saxon, D H; Schioppa, M; Schlenstedt, S; Schleper, P; Schmidke, W B; Schneekloth, U; Schönberg, V; Schörner-Sadenius, T; Schwartz, J; Sciulli, F; Shcheglova, L M; Shehzadi, R; Shimizu, S; Singh, I; Skillicorn, I O; Słomiński, W; Smith, W H; Sola, V; Solano, A; Son, D; Sosnovtsev, V; Spiridonov, A; Stadie, H; Stanco, L; Stefaniuk, N; Stern, A; Stewart, T P; Stifutkin, A; Stopa, P; Suchkov, S; Susinno, G; Suszycki, L; Sztuk-Dambietz, J; Szuba, D; Szuba, J; Tapper, A D; Tassi, E; Terrón, J; Theedt, T; Tiecke, H; Tokushuku, K; Tomaszewska, J; Trusov, V; Tsurugai, T; Turcato, M; Turkot, O; Tymieniecka, T; Vázquez, M; Verbytskyi, A; Viazlo, O; Vlasov, N N; Walczak, R; Abdullah, W A T Wan; Whitmore, J J; Wichmann, K; Wiggers, L; Wing, M; Wlasenko, M; Wolf, G; Wolfe, H; Wrona, K; Yagües-Molina, A G; Yamada, S; Yamazaki, Y; Yoshida, R; Youngman, C; Zabiegalov, O; Żarnecki, A F; Zawiejski, L; Zenaiev, O; Zeuner, W; Zhautykov, B O; Zhmak, N; Zichichi, A; Zolkapli, Z; Zotkin, D S

    2012-01-01

    The production of Z0 bosons in the reaction ep -> eZ0p*, where p* stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb-1 of integrated luminosity. The Z0 was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on eta_max eZ0p* was measured to be sigma(ep -> eZ0p*) = 0.13 +/- 0.06 (stat.) +/- 0.01 (syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z0 production in ep collisions.

  15. End to end Distance and its Probability Distribution of Polymer Chains near a Flat Barrier%平面壁限制的高分子链末端距及其概率分布

    Institute of Scientific and Technical Information of China (English)

    黄建花; 蒋文华; 韩世钧

    2001-01-01

    The problem of polymer chains near an impenetrable plane is investigated by means of the probability method. It is shown that the 2kth moment of the reduced normal component of the end-to-end distance A2k only depends on the reduced distance to the plane of the first segment AZ0, here, A=l- 1· , n is the chain length, l is the bond length and fixed to be unity, which can be expressed as A2k=f(AZ0). When AZ0≈ 0, A2k is the maximum(A2k=k!), then it decreases rapidly and soon reaches the minimum with the increase of AZ0, afterwards A2k goes up gradually and reaches the limit value [(2k- 1)× (2k- 3)× … × 1]/2k when AZ0 is large enough. Suggesting that the polymer chain can be significantly elongated for small Z0 and contracted for an intermediate range of Z0 due to the barrier. The distribution of the end-to-end distance also depends on the distance Z0 to the plane of the first segment.

  16. Lake Borgne Surge Barrier Study

    Science.gov (United States)

    2010-09-01

    Savant , and Darla C. McVan September 2010 Approved for public release; distribution is unlimited. ERDC/CHL TR-10-10 September 2010 Lake...Borgne Surge Barrier Study S. Keith Martin, Gaurav Savant , and Darla C. McVan Coastal and Hydraulics Laboratory U.S. Army Engineer Research and...conducted by Keith Martin, Dr. Gaurav Savant , and Darla C. McVan. This work was conducted at the Coastal and Hydraulics Laboratory (CHL) of the

  17. Safety-barrier diagrams

    DEFF Research Database (Denmark)

    Duijm, Nijs Jan

    2007-01-01

    are discussed. A simple method for quantification of safety-barrier diagrams is proposed, including situations where safety barriers depend on shared common elements. It is concluded that safety-barrier diagrams provide a useful framework for an electronic data structure that integrates information from risk......Safety-barrier diagrams and the related so-called "bow-tie" diagrams have become popular methods in risk analysis. This paper describes the syntax and principles for constructing consistent and valid safety-barrier diagrams. The relation with other methods such as fault trees and Bayesian networks...... analysis with operational safety management....

  18. Extremal surface barriers

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Netta; Wall, Aron C. [Department of Physics, University of California,Santa Barbara, CA 93106 (United States)

    2014-03-13

    We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy.

  19. Changes in the Expression and Distribution of Claudins, Increased Epithelial Apoptosis, and a Mannan-Binding Lectin-Associated Immune Response Lead to Barrier Dysfunction in Dextran Sodium Sulfate-Induced Rat Colitis

    Science.gov (United States)

    Yuan, Bosi; Zhou, Shuping; Lu, Youke; Liu, Jiong; Jin, Xinxin; Wan, Haijun; Wang, Fangyu

    2015-01-01

    Background/Aims This animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction. Methods Rats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay. Results The lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%±1.2% in controls and was significantly increased to 7.2%±1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis. Conclusions There was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability. PMID:25717051

  20. Barriers to screening mammography.

    Science.gov (United States)

    Sarma, Elizabeth A

    2015-01-01

    Breast cancer (BRCA) is the second most commonly diagnosed cancer among women in the USA, and mammography is an effective means for the early detection of BRCA. Identifying the barriers to screening mammography can inform research, policy and practice aiming to increase mammography adherence. A literature review was conducted to determine common barriers to screening mammography adherence. PsycINFO and PubMed databases were searched to identify studies published between 2000 and 2012 that examined barriers associated with reduced mammography adherence. Three thematic groups of barriers, based on social ecology, were identified from the literature: healthcare system-level, social and individual-level barriers. Researchers must consider screening behaviour in context and, therefore, should simultaneously consider each level of barriers when attempting to understand screening behaviour and create interventions to increase mammography adherence.

  1. Vacuum Radiation Pressure Fluctuations and Barrier Penetration

    CERN Document Server

    Huang, Haiyan

    2016-01-01

    We apply recent results on the probability distribution for quantum stress tensor fluctuations to the problem of barrier penetration by quantum particles. The probability for large stress tensor fluctuations decreases relatively slowly with increasing magnitude of the fluctuation, especially when the quantum stress tensor operator has been averaged over a finite time interval. This can lead to large vacuum radiation pressure fluctuations on charged or polarizable particles, which can in turn push the particle over a potential barrier. The rate for this effect depends sensitively upon the details of the time averaging of the stress tensor operator, which might be determined by factors such as the shape of the potential. We make some estimates for the rate of barrier penetration by this mechanism and argue that in some cases this rate can exceed the rate for quantum tunneling through the barrier. The possibility of observation of this effect is discussed.

  2. Converse Barrier Certificate Theorems

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2016-01-01

    This paper shows that a barrier certificate exists for any safe dynamical system. Specifically, we prove converse barrier certificate theorems for a class of structurally stable dynamical systems. Other authors have developed a related result by assuming that the dynamical system has neither sing...

  3. Distributed Wind Energy in Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, John [Boise State Univ., ID (United States); Johnson, Kathryn [Colorado School of Mines, Golden, CO (United States); Haynes, Todd [Boise State Univ., ID (United States); Seifert, Gary [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2009-01-31

    This project is a research and development program aimed at furthering distributed wind technology. In particular, this project addresses some of the barriers to distributed wind energy utilization in Idaho.

  4. Skin barrier function

    DEFF Research Database (Denmark)

    2016-01-01

    Renowned experts present the latest knowledge Although a very fragile structure, the skin barrier is probably one of the most important organs of the body. Inward/out it is responsible for body integrity and outward/in for keeping microbes, chemicals, and allergens from penetrating the skin. Since...... the role of barrier integrity in atopic dermatitis and the relationship to filaggrin mutations was discovered a decade ago, research focus has been on the skin barrier, and numerous new publications have become available. This book is an interdisciplinary update offering a wide range of information...... on the subject. It covers new basic research on skin markers, including results on filaggrin and on methods for the assessment of the barrier function. Biological variation and aspects of skin barrier function restoration are discussed as well. Further sections are dedicated to clinical implications of skin...

  5. Barrier traversal times using a phenomenological track formation model

    CERN Document Server

    Palao, J P; Brouard, S; Jadczyk, A

    1997-01-01

    A phenomenological model for a measurement of barrier traversal times for particles is proposed. Two idealized detectors for passage and arrival provide entrance and exit times for the barrier traversal. The averaged traversal time is computed over the ensemble of particles detected twice, before and after the barrier. The Hartman effect can still be found when passage detectors that conserve the momentum distribution of the incident packet are used.

  6. Assessment of blood brain barrier penetration of drugs using a rat steady-state brain distribution model%大鼠稳态脑分布模型评价药物的血脑屏障通透性

    Institute of Scientific and Technical Information of China (English)

    原梅; 阳海鹰; 钟玉环; 庄笑梅; 李桦

    2015-01-01

    目的 建立大鼠稳态脑分布模型用于评价安替比林、阿替洛尔和ZZB 系列新药候选化合物的稳态脑分布和血脑屏障通透性.方法 大鼠静脉推注负荷剂量的药物后恒量输注使血药浓度达到稳态,取血和脑组织样品,LC-MS/MS 定量测定血浆和脑组织药物浓度,计算稳态脑血比值(Kp值).在Caco-2 单层细胞体外模型上评价受试药物的双向跨膜通透性,计算表观通透系数(Papp).结果 安替比林和阿替洛尔分别为已知的血脑屏障易通透和难通透药物.安替比林的平均稳态脑分布浓度为(2561±125)ng/g,Kp值为0.93±0.04.阿替洛尔则分别为(20.1±0.8)ng/g 和0.015±0.002.安替比林的Kp值约为阿替洛尔的60 倍.ZZB 系列化合物的结构相似,但Kp值的差异较大,从0.044 到6.41,并与Caco-2 细胞模型的Papp值不相关.结论 建立的大鼠稳态脑分布模型可快速形成稳态血浆浓度,适用于药物血脑屏障通透程度的评价,方法简单、可靠且经济.%Objective To develop a steady-state brain distribution model in rats and to assess the blood brain barrier(BBB) penetration of antipyrine, atenolol and a group of ZZB candidate compounds. Methods Antipyrine, atenolol and ZZB compounds were administered to rats by an initial iv bolus dose (loading dose) followed by iv infusion at a constant rate for 30-40 min to reach steady-state plasma kinetics. The blood and brain tissue samples were then collected. The steady-state concentrations of the samples were measured by LC-MS/MS. The steady-state ratio of brain to plasma concentration (Kp) was calculated. The drugs and candidate compounds were also tested with Caco-2 cell model and the apparent bidirectional transport permeability coefficient (Papp) was obtained. Results Antipyrine and atenolol were known as drugs with high and low BBB penetration properties respectively. The mean brain concentrations of antipyrine and atenolol at steady-state were(2561 ± 125) and(20.1

  7. Converse Barrier Certificate Theorem

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2013-01-01

    This paper presents a converse barrier certificate theorem for a generic dynamical system.We show that a barrier certificate exists for any safe dynamical system defined on a compact manifold. Other authors have developed a related result, by assuming that the dynamical system has no singular...... points in the considered subset of the state space. In this paper, we redefine the standard notion of safety to comply with generic dynamical systems with multiple singularities. Afterwards, we prove the converse barrier certificate theorem and illustrate the differences between ours and previous work...

  8. Recycler barrier RF buckets

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  9. A mechanism study of sound wave-trapping barriers.

    Science.gov (United States)

    Yang, Cheng; Pan, Jie; Cheng, Li

    2013-09-01

    The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier.

  10. [Vascular endothelial Barrier Function].

    Science.gov (United States)

    Ivanov, A N; Puchinyan, D M; Norkin, I A

    2015-01-01

    Endothelium is an important regulator of selective permeability of the vascular wall for different molecules and cells. This review summarizes current data on endothelial barrier function. Endothelial glycocalyx structure, its function and role in the molecular transport and leukocytes migration across the endothelial barrier are discussed. The mechanisms of transcellular transport of macromolecules and cell migration through endothelial cells are reviewed. Special section of this article addresses the structure and function of tight and adherens endothelial junction, as well as their importance for the regulation of paracellular transport across the endothelial barrier. Particular attention is paid to the signaling mechanism of endothelial barrier function regulation and the factors that influence on the vascular permeability.

  11. Barriers to Effective Listening.

    Science.gov (United States)

    Hulbert, Jack E.

    1989-01-01

    Discusses the following barriers which interfere with listening efficiency: content, speaker, medium, distractions, mindset, language, listening speed, and feedback. Suggests ways to combat these obstacles to accurate comprehension. (MM)

  12. Barriers to SCM implementing

    OpenAIRE

    M.E. Rosli; B. Md Dero; A. R. Ismail; M. N. Ab Rahman

    2008-01-01

    Purpose: This paper explores the barriers faced by Malaysian manufacturing companies in successfullyimplementing the Supply Chain Management (SCM). The study has highlighted some pertinent factorsperforming the barriers that are most frequently reported by the studied companies. Sixteen companies, fromservice and manufacturing companies were studied over a period of two years to assess their SCM practicesthrough survey and interview processes.Design/methodology/approach: This part discusses t...

  13. On the porosity of barrier layers

    Directory of Open Access Journals (Sweden)

    J. Mignot

    2009-09-01

    Full Text Available Barrier layers are defined as the layer between the pycnocline and the thermocline when the latter are different as a result of salinity stratification. We present a revisited 2-degree resolution global climatology of monthly mean oceanic Barrier Layer (BL thickness first proposed by de Boyer Montégut et al. (2007. In addition to using an extended data set, we present a modified computation method that addresses the observed porosity of BLs. We name porosity the fact that barrier layers distribution can, in some areas, be very uneven regarding the space and time scales that are considered. This implies an intermittent alteration of air-sea exchanges by the BL. Therefore, it may have important consequences for the climatic impact of BLs. Differences between the two computation methods are small for robust BLs that are formed by large-scale processes. However, the former approach can significantly underestimate the thickness of short and/or localized barrier layers. This is especially the case for barrier layers formed by mesoscale mechanisms (under the intertropical convergence zone for example and along western boundary currents and equatorward of the sea surface salinity subtropical maxima. Complete characterisation of regional BL dynamics therefore requires a description of the robustness of BL distribution to assess the overall impact of BLs on the process of heat exchange between the ocean interior and the atmosphere.

  14. Hedging Double Barriers with Singles

    NARCIS (Netherlands)

    Sbuelz, A.

    2000-01-01

    Double barrier options provide risk managers with good-deal flexibility in tailoring portfolio returns.Their hedges offer full protection only if unwound along the barriers.This work provides non-dynamic hedges that project the risk of double barriers on to single barriers.Non-dynamic hedges overcom

  15. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, Roger P. (Jemez Springs, NM)

    1992-01-01

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

  16. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, R.P.

    1992-09-15

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput. 3 figs.

  17. A double barrier memristive device

    Science.gov (United States)

    Hansen, M.; Ziegler, M.; Kolberg, L.; Soni, R.; Dirkmann, S.; Mussenbrock, T.; Kohlstedt, H.

    2015-09-01

    We present a quantum mechanical memristive Nb/Al/Al2O3/NbxOy/Au device which consists of an ultra-thin memristive layer (NbxOy) sandwiched between an Al2O3 tunnel barrier and a Schottky-like contact. A highly uniform current distribution for the LRS (low resistance state) and HRS (high resistance state) for areas ranging between 70 μm2 and 2300 μm2 were obtained, which indicates a non-filamentary based resistive switching mechanism. In a detailed experimental and theoretical analysis we show evidence that resistive switching originates from oxygen diffusion and modifications of the local electronic interface states within the NbxOy layer, which influences the interface properties of the Au (Schottky) contact and of the Al2O3 tunneling barrier, respectively. The presented device might offer several benefits like an intrinsic current compliance, improved retention and no need for an electric forming procedure, which is especially attractive for possible applications in highly dense random access memories or neuromorphic mixed signal circuits.

  18. Barriers to cancer screening.

    Science.gov (United States)

    Womeodu, R J; Bailey, J E

    1996-01-01

    Many barriers to cancer screening have been summarized and discussed. Barriers have been documented in all patient populations, but some groups such as ethnic minorities and the elderly face unique barriers. The barriers to cancer screening, are multifactorial, but much of the responsibility for change must lie with health care providers and the health care delivery industry. This is not to free the patient of all responsibility, but some significant barriers are beyond their direct control. Take, for example, socioeconomic status, disease knowledge, and culturally related perceptions and myths about cancer detection and treatment. The health care industry must do a better job identifying and overcoming these barriers. The significant effects of provider counseling and advice must not be underestimated. Patients must first be advised, and then further actions must be taken if they reject the screening advice. Did they refuse adherence to recommendations because they do not view themselves as susceptible, because of overwhelming personal barriers, or because of a fatalistic attitude toward cancer detection and treatment? If that is the case, physicians and health care institutions must attempt to change perceptions, educate, and personalize the message so that patients accept their disease susceptibility [table: see text]. Multiple patient and provider risk factors have been identified that can be used to target patients particularly at high risk for inadequate cancer screening and providers at high risk for performing inadequate screening. Research has clearly demonstrated the effectiveness of interventions to improve tracking of patient and physician compliance with screening recommendations. Further research is needed to show the impact of managed-care penetration and payer status on screening efforts, and incentive schemes need to be tested that reward institutions and third-party payers who develop uniform standards and procedures for cancer screening. The

  19. Overcoming barriers to Clean Development Mechanism projects

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, J. [OECD, Paris (France); Kamel, S. [UNEP Risoe Centre on Energy, Climate and Sustainable Development URC, Roskilde (Denmark)

    2007-05-15

    The market for Clean Development Mechanism (CDM) projects is continuing to grow rapidly, with the current portfolio expecting to deliver 2 billion tons of CO2-eq greenhouse gas (GHG) emission reductions by 2012, equivalent to 17% of Annex I Parties' base year GHG emissions. In total, governments and companies have earmarked over USD11 billion for CDM funding to 2012. This study analyses the various barriers to CDM market expansion in developing countries, and makes recommendations on how some of them can be removed or reduced. It also examines the distribution of CDM projects amongst regions and sectors. Different types of barriers can impede the development of CDM projects. These include: National-level barriers not related specifically to the CDM such as the policy or legislative framework within which a CDM project operates, e.g. electricity-related regulations that constrain generation by independent power producers; National-level CDM-related barriers such as institutional capability/effectiveness or lack of awareness about CDM potential. For example, delays in host country approval of CDM projects can dampen interest in CDM project development; Project-related issues including availability (or not) of underlying project finance, or other country or project-related risks that render the performance of the project uncertain; International-level barriers such as constraints on project eligibility (e.g. on land use and forestry projects), available guidance and decisions (e.g. with respect to the inclusion of carbon capture and storage projects), etc. Thus, barriers to CDM development can arise at different parts of the CDM project cycle. The relative importance of particular barriers varies between countries as well as over time. A combination of factors is needed to drive growth in a country's CDM activity. This includes the presence of attractive CDM opportunities, a positive investment climate, and an enabling policy and legislative framework (in

  20. Numerical investigation of dielectric barrier discharges

    Science.gov (United States)

    Li, Jing

    1997-12-01

    A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in

  1. LANGUAGE BARRIERS: FEEDBACK FROM THE IT INDUSTRY

    Directory of Open Access Journals (Sweden)

    Sareen Kaur Bhar

    2013-02-01

    Full Text Available Meaningful interaction process between human beings necessitates effective communication especially in organisations that have rapid information exchange demands. It is perceived that most IT organisations that face communication and language barriers have lost businesses due to higher product defect rates, lack of focus on business objectives, stifled innovation and dissatisfied customers and poor customer services. This study looks at the language barriers faced by employees working in various fields related to Information Technology in Malaysia. A questionnaire was distributed to IT employees working in various international and national companies in Malaysia, and sixty two IT employees’ responses were accepted. The employees had to rate the effects of each language barrier on them in the context of the workplace. Based on these findings, barriers faced by IT employees in this field can now be better understood and steps can be taken by both the industry and education sectors to overcome these barriers. It will also aid these employees to be better communicators in facing the challenges in their industry and increase their competitiveness on a global scale. We conclude that future research should more explicitly consider the different configurations of language skills that are needed by IT staff.

  2. Support or Barrier?

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    This study offers a critical look at how corporate-level language management influences front-line language practices among employees in three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data, we examine, firstly, what front-line practices emplo...... to a discussion of how a company’s language policy may be seen as both support and a barrier....

  3. Overcoming Language Barriers

    Science.gov (United States)

    De Buda, Yvonne

    1976-01-01

    Many family physicians in Canada experience language and cultural barriers between themselves and their patients. Several aspects of the ensuing problems are described and some practical suggestions for solutions are made. The importance of health education for new Canadians in the family physician's office as well as through the media and community projects is stressed. Imagesp68-ap68-bp70-a PMID:21308059

  4. Barriers to obesity treatment.

    Science.gov (United States)

    Mauro, Marina; Taylor, Valerie; Wharton, Sean; Sharma, Arya M

    2008-05-01

    Obesity, one of the most prevalent health problems in the Western world, is a chronic and progressive condition. Therefore, as with other chronic diseases, patients with obesity require lifelong treatment. Long-term efficacy and effectiveness of obesity treatments is notoriously poor. This may in part be attributable to the substantial barriers that undermine long-term obesity management strategies. These can include lack of recognition of obesity as a chronic condition, low socioeconomic status, time constraints, intimate saboteurs, and a wide range of comorbidities including mental health, sleep, chronic pain, musculoskeletal, cardiovascular, respiratory, digestive and endocrine disorders. Furthermore, medications used to treat some of these disorders may further undermine weight-loss efforts. Lack of specific obesity training of health professionals, attitudes and beliefs as well as coverage and availability of obesity treatments can likewise pose important barriers. Health professionals need to take care to identify, acknowledge and address these barriers where possible to increase patient success as well as compliance and adherence with treatments. Failure to do so may further undermine the sense of failure, low self esteem and self efficacy already common among obese individuals. Addressing treatment barriers can save resources and increase the prospect of long-term success.

  5. Barrier inhomogeneities and interface states of metal/4H-SiC Schottky contacts

    Science.gov (United States)

    Huang, Lingqin; Geiod, Rechard; Wang, Dejun

    2016-12-01

    The barrier and interface states of Ti, Mo, Ni, and Pt contacts to 4H-SiC were investigated. It is found that the barrier heights for all the contacts are Gaussianly distributed and the barrier inhomogeneity varies with the contact metal type. However, the energy-averaged interface states density in the band gap is metal-insensitive. When considering Gaussian distribution, the interface states density extracted from the electrical properties is consistent with the average density of Gaussianly distributed 4H-SiC surface states, indicating that the barrier inhomogeneities at metal/SiC contacts mainly originate from the spatial variation of surface states on SiC surface. The barrier height and barrier inhomogeneity could be modulated by the contact metal, obeying the barrier height theory of Cowley and Sze.

  6. Barrier mechanisms in the Drosophila blood-brain barrier

    OpenAIRE

    Samantha Jane Hindle; Roland Jerome Bainton

    2014-01-01

    The invertebrate blood-brain barrier field is growing at a rapid pace and, in recent years, studies have shown a physiologic and molecular complexity that has begun to rival its vertebrate counterpart. Novel mechanisms of paracellular barrier maintenance through GPCR signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate blood-brain barrier has recently been shown to require coordinated funct...

  7. Geophysical characterization of subsurface barriers

    Energy Technology Data Exchange (ETDEWEB)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.

  8. Barriers to Combating Human Trafficking in Colombia

    Science.gov (United States)

    2015-03-01

    COMBATING HUMAN TRAFFICKING IN COLOMBIA by Daniel Joseph Wilcox March 2015 Thesis Advisor: Rodrigo Nieto-Gómez Second Reader: Maiah Jaskoski...Master ’s Thesis 4. TITLE AND SUBTITLE BARRIERS TO COMBATING HUMAN TRAFFICKING IN COLOMBIA 6. AUTHOR(S) Daniel Joseph Wilcox 7. PERFORMING...maximum 200 words) 12b. DISTRIBUTION CODE Despite intema.tional and domestic policies and programs intended to combat human trafficking , Colombia

  9. Sound absorption mapping of highway noise barrier

    OpenAIRE

    Grosso, Andrea

    2012-01-01

    International audience; Sound propagation from highway to the urban areas can be reduced using noise barriers. The general computational modeling takes typically into account sound ray lines, reflection and diffraction, although the absorption distribution over the surface in not considered. The sound absorption coefficient can be calculated using a PU probe, by the impedance measured “in situ” close by the surface. Well known methods are available on the market for estimating the sound absor...

  10. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, R.P.

    1990-10-10

    This invention is comprised of a barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yearns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

  11. [The cultural barrier in care].

    Science.gov (United States)

    Djadaoudjee, Lisa

    2013-11-01

    French cultural diversity is evident within French hospitals, where nurses are confronted with communication problems resulting from the language barrier. While communication is indeed essential, there is another important aspect of caring for a patient for behind the language barrier lies a cultural barrier which must be taken into account in order to provide high-quality care.

  12. Thermal barrier coating materials

    Directory of Open Access Journals (Sweden)

    David R. Clarke

    2005-06-01

    Full Text Available Improved thermal barrier coatings (TBCs will enable future gas turbines to operate at higher gas temperatures. Considerable effort is being invested, therefore, in identifying new materials with even better performance than the current industry standard, yttria-stabilized zirconia (YSZ. We review recent progress and suggest that an integrated strategy of experiment, intuitive arguments based on crystallography, and simulation may lead most rapidly to the development of new TBC materials.

  13. Simulation of the interaction of tsunami waves with underwater barriers

    Science.gov (United States)

    Boshenyatov, B. V.; Zhiltsov, K. N.

    2016-10-01

    This article examines the experimental and numerical simulation of the processes of distribution and interaction of tsunami-type gravitational waves with one barrier and a complex of two barriers. Experiments were conducted in a hydrodynamic channel using high-precision sensors for the measurement of the wave processes. Mathematical modelling was carried out using two-dimensional non-stationary Navier-Stokes equations for an incompressible fluid using the freely available software package OpenFOAM. It is shown that for small-amplitude waves, when their advance speed is described by the linear theory of shallow water, the interaction with the underwater barriers has important non-linear and viscous effects. Our results explain why a complex of two barriers spaced at a definite distance from each other has a significant impact on the power of the transmitted wave. The energy of the waves passing through the two barriers can be reduced to 35% of the incident wave.

  14. On causality, apparent 'superluminality' and reshaping in barrier penetration

    CERN Document Server

    Sokolovski, D

    2010-01-01

    We consider tunnelling of a non-relativistic particle across a potential barrier. It is shown that the barrier acts as an effective beam splitter which builds up the transmitted pulse from the copies of the initial envelope shifted in the coordinate space backwards relative to the free propagation. Although along each pathway causality is explicitly obeyed, in special cases reshaping can result an overall reduction of the initial envelope, accompanied by an arbitrary coordinate shift. In the case of a high barrier the delay amplitude distribution (DAD) mimics a Dirac $\\delta$-function, the transmission amplitude is superoscillatory for finite momenta and tunnelling leads to an accurate advancement of the (reduced) initial envelope by the barrier width. In the case of a wide barrier, initial envelope is accurately translated into the complex coordinate plane. The complex shift, given by the first moment of the DAD, accounts for both the displacement of the maximum of the transmitted probability density and the...

  15. Characterizing Surface Transport Barriers in the South China Sea

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Characterizing Surface Transport Barriers in the South...in mathematical methods for detecting key Lagrangian transport structures in velocity field data sets for spatially complex, time- dependent, ocean...surface flows. Such transport structures are typically not inherently obvious in snapshots of the Eulerian velocity field and require analysis

  16. Deep inelastic scattering near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, J.; Back, B.; Chan, K. [and others

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  17. Barrier mechanisms in the Drosophila blood-brain barrier

    Directory of Open Access Journals (Sweden)

    Samantha Jane Hindle

    2014-12-01

    Full Text Available The invertebrate blood-brain barrier field is growing at a rapid pace and, in recent years, studies have shown a physiologic and molecular complexity that has begun to rival its vertebrate counterpart. Novel mechanisms of paracellular barrier maintenance through GPCR signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate blood-brain barrier has recently been shown to require coordinated function of all layers of the compound barrier structure, analogous to signaling between the layers of the vertebrate neurovascular unit. These findings strengthen the notion that many blood-brain barrier mechanisms are conserved between vertebrates and invertebrates, and suggest that novel findings in invertebrate model organisms will have a significant impact on the understanding of vertebrate BBB functions. In this vein, important roles in coordinating localized and systemic signaling to dictate organism development and growth are beginning to show how the blood-brain barrier can govern whole animal physiologies. This includes novel functions of blood-brain barrier gap junctions in orchestrating synchronized neuroblast proliferation, and of blood-brain barrier secreted antagonists of insulin receptor signaling. These advancements and others are pushing the field forward in exciting new directions. In this review, we provide a synopsis of invertebrate blood-brain barrier anatomy and physiology, with a focus on insights from the past 5 years, and highlight important areas for future study.

  18. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst...

  19. [Barrier methods of contraception].

    Science.gov (United States)

    Goldsmith, A; Edelman, D A

    1982-01-01

    Vaginal methods of contraception were the earliest types used and some references to them date back to antiquity. Most of the vaginal contraceptive agents identified by the ancient Greeks, Indians, Japanese, and Chinese have been found in modern laboratory tests to have spermicidal properties, but it is doubtful that the methods were fully reliable or were used by many people. During the 19th century the condom, vaginal spermicides, and diaphragm became available. The development of nonoxynol-9 and other nonirritating but effective spermicidal agents improved vaginal contraceptives greatly by the 1950s, but starting in the 1960s newer methods began to replace the vaginal methods. Interest in barrier methods has been reawakened somewhat by concern about the health effects of hormonal methods. At present all barrier methods leave something to be desired. Failure rates of 3-30% for barrier methods in general have been estimated, but the higher rates are believed due to incorrect or inconsistent use. Theoretical failure rates of condoms and diaphragms have been estimated at 3/100 women-years, but in actual use failure rates may reach 15 for condoms and 13 for diaphragms used with spermicides. Use-effectiveness rates are greatly influenced by motivation. For a variety of reasons, the acceptability of barrier methods is low, especially in developing countries. New developments in spermicidal agents include sperm inhibitors, which impede the fertilizing capacity of sperm rather than attempting a spermicidal effect; a number of such agents have been studied and have proven more effective in animal tests than conventional spermicides. Neosampoon, a new spermicidal foam, has attracted an increasing number of users, especially in developing countries. A new condom, made of thin polymers and containing a standard dose of nonoxynol-9, has been designed to dissolve in the vaginal fluid. Further studies are needed of its acceptability, efficacy, and side effects before it becomes

  20. Technical barrier challenges

    Institute of Scientific and Technical Information of China (English)

    李思佳

    2014-01-01

    according to a famouse report,the foreign Technical Barriers to Trade(TBT)have some effects on the exports of the People’s Republic of China.Major findings are as follows:(1)TBT makes it more difficult for China to export;(2)TBT increases the costs of Chinese export commodities;(3)TBT causes friction and confilicts in the international trade;(4)SOME developed countries have moved their phase-outs to China and other developing countries,which have become victims of TBT.

  1. Support or Barrier?

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    This study offers a critical look at how corporate-level language management influences front-line language practices among employees in three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data, we examine, firstly, what front-line practices...... employees use to cross language boundaries in their everyday work, and, secondly, how these practices relate to top-down language management in the case companies. Our findings show that employees are often dependent on ad hoc and informal solutions in cross- language situations, which leads us...... to a discussion of how a company’s language policy may be seen as both support and a barrier....

  2. Room-temperature dynamic quasi-elastic mechanical behavior of a Zr-Cu-Fe-Al bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zadorozhnyy, V.Yu.; Zadorozhnyy, M.Yu.; Shuryumov, A.Yu.; Golovin, I.S. [National University of Science and Technology ' ' MISiS' ' , 119049, Moscow (Russian Federation); Ketov, S.V.; Louzguine-Luzgin, D.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577 (Japan)

    2016-02-15

    The paper represents storage modulus and internal friction modulation upon cyclic loading of Zr{sub 61}Cu{sub 27}Fe{sub 2}Al{sub 10} bulk metallic glassy samples within quasi-reversible deformation regime. The structure of the samples was studied by X-ray diffraction and transmission electron microscopy including high-resolution imaging and selected-area electron diffraction. It is found that kinetically frozen anelastic deformation accumulates on mechanical cycling at room temperature and causes an increase in the storage modulus and even nanocrystallization of a metallic glassy phase after a certain number of cycles. The study has shown that even a minor cyclic deformation in an elastic region can lead to the changes the atomic structure and in turn affect the elastic modulus. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Production of Z{sup 0} bosons in elastic and quasi-elastic ep collisions at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

    2012-10-15

    The production of Z{sup 0} bosons in the reaction ep {yields} eZ{sup 0}p{sup (*)}, where p{sup (*)} stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb{sup -1} of integrated luminosity. The Z{sup 0} was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on {eta}{sub max} < 3.0, where {eta}{sub max} is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z{sup 0} mass. The cross section of the reaction ep {yields} eZ{sup 0}p{sup (*)} was measured to be {sigma} (ep {yields} eZ{sup 0}p{sup (*)}) = 0.13 {+-} 0.06 (stat.) {+-} 0.01 (syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z{sup 0} production in ep collisions.

  4. Transport of nanoparticles through the placental barrier.

    Science.gov (United States)

    Kulvietis, Vytautas; Zalgeviciene, Violeta; Didziapetriene, Janina; Rotomskis, Ricardas

    2011-12-01

    Nanoparticles (NP) are organic or inorganic substances, the size of which ranges from 1 to 100 nm, and they possess specific properties which are different from those of the bulk materials in the macroscopic scale. In a recent decade, NP were widely applied in biomedicine as potential probes for imaging, drug-delivery systems and regenerative medicine. However, rapid development of nanotechnologies and their applications in clinical research have raised concerns about the adverse effects of NP on human health and environment. In the present review, special attention is paid to the fetal exposure to NP during the period of pregnancy. The ability to control the beneficial effects of NP and to avoid toxicity during treatment requires comprehensive knowledge about the distribution of NP in maternal body and possible penetration through the maternal-fetal barrier that might impair the embryogenesis. The initial in vivo and ex vivo studies imply that NP are able to cross the placental barrier, but the passage to the fetus depends on the size and the surface coating of NP as well as on the experimental model. The toxicity assays indicate that NP might induce adverse physiological effects and impede embryogenesis. The molecular transport mechanisms which are responsible for the transport of nanomaterials across the placental barrier are still poorly understood, and there is a high need for further studies in order to resolve the NP distribution patterns in the organism and to control the beneficial effects of NP applications during pregnancy without impeding the embryogenesis.

  5. Optimum Barrier Height for SiC Schottky Barrier Diode

    OpenAIRE

    Mohamed Abd El-Latif; Alaa El-Din Sayed Hafez

    2013-01-01

    The study of barrier height control and optimization for Schottky barrier diode (SBD) from its physical parameters have been introduced using particle swarm optimization (PSO) algorithm. SBD is the rectifying barrier for electrical conduction across the metal semiconductor (MS) junction and, therefore, is of vital importance to the successful operation of any semiconductor device. 4H-SiC is used as a semiconductor material for its good electrical characteristics with high-power semiconductor ...

  6. 大气压介质阻挡射流放电离子速度分布的测量%Measurement of ion velocity distribution in plasma jet with dielectric barrier geometry at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    熊莉; 齐冰

    2016-01-01

    A new method based on fast Fourier transform, is presented to calculate ion velocity distribution by analyzing electromagnetic radiation signal from atmospheric nonequilibrium plasma. This method is based on a dipole model. Results show that the ion velocity distribution deviates from Maxwell distribution over time. The ion velocity and relative ion number fluctuate regularly with time.%通过测量大气压介质阻挡放电等离子体辐射信号,建立偶极子辐射模型,利用快速傅立叶变换,计算了大气压介质阻挡放电等离子体中离子速度分布。计算结果表明,速度分布偏离麦克斯韦分布,并且随着放电过程的进行,离子速度及相对离子数进行有规律的变化。

  7. Higgs vacua behind barriers

    CERN Document Server

    Tamarit, Carlos

    2014-01-01

    Scenarios in which the Higgs vacuum arises radiatively and separated from the origin by a potential barrier at zero temperature are known to be attainable in models with extra singlet scalars, which in the limit of zero barrier height give rise to Coleman-Weinberg realizations of electroweak symmetry breaking. However, this requires large values of Higgs-portal couplings or a large number N of singlets. This is quantified in detail by considering, for varying N, the full two-loop effective potential at zero temperature, as well as finite temperature effects including the dominant two-loop corrections due to the singlets. Despite the large couplings, two-loop effects near the electroweak scale are under control, and actually better behaved in models with larger couplings yet fewer singlets. Strong first-order phase transitions are guaranteed even in the Coleman-Weinberg scenarios. Cubic Higgs couplings and Higgs associated-production cross sections exhibit deviations from the Standard Model predictions which c...

  8. Stability of barrier buckets with zero RF-barrier separations

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab

    2005-03-01

    A barrier bucket with very small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly from a large value towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and/or rf phase. In addition, chaotic regions may form near the bucket center and extend outward under increasing modulation. Application is made to those barrier buckets used in the process of momentum mining at the Fermilab Recycler Ring.

  9. Ranking different barriers influencing on media privatization

    Directory of Open Access Journals (Sweden)

    Roghiyeh Jame

    2014-02-01

    Full Text Available For years, there have been growing interests on cost reduction for products and services. Privatization is considered as one of the most important techniques to increase relative efficiencies of publically held firms. In this paper, we present an empirical investigation to rank important barriers on privatization of television (TV media industry in Iran. The proposed study of this paper designs and distributes a questionnaire using a sample of 234 out of 600 graduate students who were enrolled in media communication studies. The survey considers social, cultural, economic as well as rules and regulations factors influencing privatization of TV media industry. The survey uses the ranking method presented by Cook and Kress (1990 [Cook, W. D., & Kress, M. (1990. A data envelopment model for aggregating preference rankings. Management Science, 36(11, 1302-1310.]. The results of the investigation indicate rules and regulations are the most important barriers on privatization of Iranian TV followed by cultural, social and economic factors.

  10. Tantalum Sheet for Superconductor Diffusion Barrier Applications

    Science.gov (United States)

    Mathaudhu, S. N.; Hartwig, K. T.; Barber, R. E.; Pyon, T.

    2006-03-01

    This report presents preliminary results of a project with the aim to fabricate fine-grained tantalum sheet having a uniform microstructure that co-deforms well with pure copper for superconductor diffusion barrier applications. Multi-pass equal channel angular extrusion (ECAE) was used to refine the microstructure of 25 mm square cross-section bars of Ta; rolling was used to convert the bars to 0.38 mm thick sheet. Cu-Ta co-deformation characteristics were evaluated by assembling and drawing experimental Cu-Ta composite wires, containing the ECAE processed sheets, to 0.83 mm diameter and metallographically examining the thinned 2-4 micron Ta layer. The ECAE processed Ta sheet co-deformed well with Cu, and was found to have a smaller recrystallized grain size, a narrower grain size distribution and a slightly higher hardness compared to commercial diffusion barrier grade Ta sheet. The favorable results encourage further work.

  11. Investigating the barriers on media privatization

    Directory of Open Access Journals (Sweden)

    Roghiyeh Jame

    2013-01-01

    Full Text Available During the past few years, there has been growing interests in reducing cost of products and services among developing countries. Privatization is believed to be one of the most important techniques to increase relative efficiencies of publically held organizations. In this paper, we study important barriers on privatization of television (TV media industry in Iran. The proposed study of this paper designs and distributes a questionnaire using a sample of 234 out of 600 graduate students who were enrolled in media communication studies and examined six hypotheses based on one-side t-student. The survey considers different factors influencing privatization of TV media industry. The results of the investigation indicate that the cost of TV production, short and long-term investment security, people's interest on investing on TV media industry, building appropriate culture, cultural obstacles and economic barriers influence media privatization, significantly.

  12. Silicon Carbide Schottky Barrier Diode

    Science.gov (United States)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  13. Translating barriers into potential improvements

    DEFF Research Database (Denmark)

    Altintzoglou, Themistoklis; Hansen, Karina Birch; Valsdottir, Thora

    2010-01-01

    Purpose: The aim of this study is to explore potential barriers to seafood consumption by The aim of this study is to explore potential barriers to seafood consumption by young adults and the parents of young children. Knowledge of these barriers will be used to assist the development of new...... to lead to practical input The present study combines qualitative methods to lead to practical input for NPD focusing on overcoming the barriers that keep consumers from choosing existing healthy seafood products. The importance of the consumers' confidence in their ability to successfully prepare...

  14. Effects of Fe on properties of Zr barriers

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, D.R.; Wisner, S.B.; Farkas, D.M.; Adamson, R.B. [GE Nuclear Energy, San Jose (United States)

    1999-07-01

    Zircaloy-2 barrier fuel having an inner surface layer of 'pure' zirconium (barrier) has been successful in eliminating fuel failures by the pellet cladding interaction (PCI) mechanism during power maneuvers in boiling water reactors (BWRs). Barrier purity and the softness of Zr relative to Zircaloy were originally the barrier characteristics of most interest, as PCI resistance depended upon them. To insure effective performance, impurity levels of the Zr were controlled such that the two major impurities, iron and oxygen, were generally kept to less than 500 ppm each. Recently there has been more interest in improving the inner surface corrosion resistance of barrier cladding in case of water or steam ingress due to a primary leak in the cladding. Increasing the Fe concentration in Zr is known to improve corrosion resistance of the barrier but at the possible risk of increasing PCI susceptibility. Therefore a series of laboratory studies were conducted to determine the range of Fe concentration which would optimize barrier performance. Zr barrier Fe concentrations in the range 90 - 3000 ppm were investigated. Corrosion testing in steam revealed a general increase in corrosion resistance with increasing Fe content, with the rate of change being most rapid in the 90 - 1000 ppm range. PCI resistance as determined by the GE Expanding Mandrel Test was found to be excellent in the range 400 - 1000 ppm Fe, but at 3000 ppm Fe the barrier was less resistant to iodine stress corrosion cracking and to PCI-type tubing failure. Further understanding of the results was obtained through detailed characterization of the size, distribution and composition of Fe-Zr second phases in the barrier. (authors)

  15. Countermeasures and barriers

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Johannes [Oersted - DTU, Automation, Kgs. Lyngby (Denmark)

    2005-10-01

    In 1973 Haddon proposed ten strategies for reducing and avoiding damages based on a model of potential harmful energy transfer (Haddon, 1973). The strategies apply to a large variety of unwanted phenomena. Haddon's pioneering work on countermeasures has had a major influence on later thinking about safety. Considering its impact it is remarkable that the literature offers almost no discussions related to the theoretical foundations of Haddon's countermeasure strategies. The present report addresses a number of theoretical issues related to Haddon's countermeasure strategies, which are: 1) A reformulation and formalization of Haddon's countermeasure strategies. 2) An identification and description of some of the problems associated with the term 'barrier'. 3) Suggestions for a more precise terminology based on the causal structure of countermeasures. 4) Extending the scope of countermeasures to include sign-based countermeasures. (au)

  16. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst......The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... groups, the sociology of work needs to develop a better understanding of the way in which linguistic diversity influences the formation of social capital, i.e. resources such as the trust and reciprocity inherent in social relations in such workplaces. Drawing on theories about intergroup contact...

  17. Barrier and porous anodic oxides on InSb

    Energy Technology Data Exchange (ETDEWEB)

    Suleiman, A.; Hashimoto, T. [Corrosion and Protection Centre, School of Materials, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Skeldon, P. [Corrosion and Protection Centre, School of Materials, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)], E-mail: peter.skeldon@manchester.ac.uk; Thompson, G.E. [Corrosion and Protection Centre, School of Materials, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Echeverria, F. [Dpto de Ing. Metalurgica y de Materiales, Universidad de Antioquia, Oficina 18-240, Calle 67 No. 53-108, A.A. 1226, Medellin (Colombia); Graham, M.J.; Sproule, G.I.; Moisa, S. [Institute for Microstructural Sciences, National Research Council of Canada, Montreal Road, Ottawa, K1A 0R6 (Canada); Habazaki, H. [Graduate Engineering School, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Bailey, P.; Noakes, T.C.Q. [Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom)

    2008-05-15

    Anodizing of InSb at 5 mA cm{sup -2} in sodium tungstate electrolyte is shown to produce barrier-type amorphous oxide at relatively low voltages, to about 40 V, and porous-type amorphous oxide at increased voltages. The barrier-type amorphous oxide, consisting of units of In{sub 2}O{sub 3} and Sb{sub 2}O{sub 3}, distributed relatively uniformly throughout the film, develops at a formation ratio of 2.2 {+-} 0.2 nm V{sup -1}. The outer 15-20% of the film also contains tungsten species. The relatively high efficiency of barrier film growth reduces significantly with transition to porous oxide, which is associated additionally with generation of oxygen at the film surface. The final oxide, at 65 V, comprises pores, of typical diameter 80 nm, orientated approximately normal to the substrate and extending from a barrier region to the film surface.

  18. Informal export barriers and poverty

    OpenAIRE

    Porto, Guido G.

    2004-01-01

    The author investigates the poverty impacts of informal export barriers like transport costs, cumbersome customs practices, costly regulations, and bribes. He models these informal barriers as export taxes that distort the efficient allocation of resources. In low-income agricultural economies, this distortion lowers wages and household agricultural income, thereby leading to higher pover...

  19. Barriers to Women in Science

    Science.gov (United States)

    Butler, Rosemary

    2013-01-01

    The Presiding Officer of the National Assembly for Wales, Rosemary Butler AM, has put the issue of barriers to women in public life at the top of the political agenda in Wales. She has held sessions with women across Wales to find out what those barriers are and how they can be tackled. On International Women's Day in February, she invited…

  20. Barriers to Women in Science

    Science.gov (United States)

    Butler, Rosemary

    2013-01-01

    The Presiding Officer of the National Assembly for Wales, Rosemary Butler AM, has put the issue of barriers to women in public life at the top of the political agenda in Wales. She has held sessions with women across Wales to find out what those barriers are and how they can be tackled. On International Women's Day in February, she invited…

  1. BARRIERS OF STRATEGIC ALLIANCES ORGANIZATION

    Directory of Open Access Journals (Sweden)

    Vladislav M. Sannikov

    2014-01-01

    Full Text Available General barriers of organization of different types of strategic alliances have beenconsidered in the article. There are several recommendations for overcoming themin cases of international alliances, and in case of work in one state. The article also identified goals and tasks of single coordination center of alliance to overcome organization barriers.

  2. Spanning trees crossing few barriers

    NARCIS (Netherlands)

    Asano, T.; Berg, M. de; Cheong, O.; Guibas, L.J.; Snoeyink, J.; Tamaki, H.

    2002-01-01

    We consider the problem of finding low-cost spanning trees for sets of n points in the plane, where the cost of a spanning tree is defined as the total number of intersections of tree edges with a given set of m barriers. We obtain the following results: (i) if the barriers are possibly intersecting

  3. Epistemological barriers to radical behaviorism.

    Science.gov (United States)

    O'Donohue, W T; Callaghan, G M; Ruckstuhl, L E

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers.

  4. Epistemological barriers to radical behaviorism

    Science.gov (United States)

    O'Donohue, William T.; Callaghan, Glenn M.; Ruckstuhl, L. E.

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  5. New records of Cotylea (Polycladida, Platyhelminthes) from Lizard Island, Great Barrier Reef, Australia, with remarks on the distribution of the Pseudoceros Lang, 1884 and Pseudobiceros Faubel, 1984 species of the Indo-Pacific Marine Region.

    Science.gov (United States)

    Marquina, Daniel; Aguado, M Teresa; Noreña, Carolina

    2015-09-18

    In the present work eleven polyclad species of Lizard Island are studied. Seven of them are new records for this locality of the Australian coral reef and one is new to science, Lurymare clavocapitata n. sp. (Family Prosthiostomidae). The remaining recorded species belong to the genera Pseudoceros (P. bimarginatus, P. jebborum, P. stimpsoni, P. zebra, P. paralaticlavus and P. prudhoei) and Pseudobiceros (Pb. hancockanus, Pb. hymanae, Pb. flowersi and Pb. uniarborensis). Regardless of the different distribution patterns, all pseudocerotid species show brilliant colours, but similar internal morphology. Furthermore, differences in the form and size of the stylet are characteristic, because it is a sclerotic structure that is not affected during fixation. In Pseudoceros, the distance between the sucker and the female pore also differs among species. These features do not vary enough to be considered as diagnostic, but they provide information that can help to disentangle similarly coloured species complexes. A key of the genera Pseudoceros and Pseudobiceros of the Indo-Pacific region is provided, in order to facilitate the identification of species from this area.

  6. The barrier within: endothelial transport of hormones.

    Science.gov (United States)

    Kolka, Cathryn M; Bergman, Richard N

    2012-08-01

    Hormones are involved in a plethora of processes including development and growth, metabolism, mood, and immune responses. These essential functions are dependent on the ability of the hormone to access its target tissue. In the case of endocrine hormones that are transported through the blood, this often means that the endothelium must be crossed. Many studies have shown that the concentrations of hormones and nutrients in blood can be very different from those surrounding the cells on the tissue side of the blood vessel endothelium, suggesting that transport across this barrier can be rate limiting for hormone action. This transport can be regulated by altering the surface area of the blood vessel available for diffusion through to the underlying tissue or by the permeability of the endothelium. Many hormones are known to directly or indirectly affect the endothelial barrier, thus affecting their own distribution to their target tissues. Dysfunction of the endothelial barrier is found in many diseases, particularly those associated with the metabolic syndrome. The interrelatedness of hormones may help to explain why the cluster of diseases in the metabolic syndrome occur together so frequently and suggests that treating the endothelium may ameliorate defects in more than one disease. Here, we review the structure and function of the endothelium, its contribution to the function of hormones, and its involvement in disease.

  7. Development of engineered barrier

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

    1999-03-01

    Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

  8. Moisture monitoring in waste disposal surface barriers.

    Science.gov (United States)

    Brandelik, Alex; Huebner, Christof

    2003-05-01

    Surface barriers for waste disposal sites should prevent waste water and gas emission into the environment. It is necessary to assess their proper operation by monitoring the water regime of the containment. A set of three new water content measuring devices has been developed that provide an economical solution for monitoring the moisture distribution and water dynamic. They will give an early warning service if the barrier system is at risk of being damaged. The cryo soil moisture sensor 'LUMBRICUS' is an in situ self-calibrating absolute water content measuring device. It measures moisture profiles at spot locations down to 2.5 m depth with an accuracy of better than 1.5% and a depth resolution of 0.03 m. The sensor inherently measures density changes and initial cracks of shrinking materials like clay minerals. The large area soil moisture sensor 'TAUPE' is a moisture sensitive electric cable network to be buried in the mineral barrier material of the cover. A report will be given with results and experiences on an exemplary installation at the Waste Disposal Facility Karlsruhe-West. 800 m2 of the barrier construction have been continuously monitored since December 1997. Volumetric water content differences of 1.5% have been detected and localised within 4 m. This device is already installed in two other waste disposal sites. A modified 'TAUPE' was constructed for the control of tunnels and river dams as well. Thin sheet moisture sensor 'FORMI' is specifically designed for moisture measurements in liners like bentonite, textile and plastic. Due to its flexibility it follows the curvature of the liner. The sensor measures independently from neighbouring materials and can be matched to a wide range of different thickness of the material. The sensors are patented in several countries.

  9. Alternating InGaN barriers with GaN barriers for enhancing optical performance in InGaN light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yujue; Zeng, Yiping, E-mail: ypzeng@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2015-01-21

    InGaN-based light-emitting diodes (LEDs) with some specific designs on the quantum barrier layers by alternating InGaN barriers with GaN barriers are proposed and studied numerically. In the proposed structure, simulation results show that the carriers are widely dispersed in the multi-quantum well active region, and the radiative recombination rate is efficiently improved and the electron leakage is suppressed accordingly, due to the appropriate band engineering. The internal quantum efficiency and light-output power are thus markedly enhanced and the efficiency droop is smaller, compared to the original structures with GaN barriers or InGaN barriers. Moreover, the gradually decrease of indium composition in the alternating quantum barriers can further promote the LED performance because of the more uniform carrier distribution, which provides us a simple but highly effective approach for high-performance LED applications.

  10. Tritium/hydrogen barrier development

    Energy Technology Data Exchange (ETDEWEB)

    Hollenberg, G.W.; Simonen, E.P. [Pacific Northwest Lab., Richland, WA (United States); Kalinen, G. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany). International Thermonuclear Experimental Reactor (ITER) Team; Terlain, A. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Service de la Corrosion, d`Electrochimie et Chimie des Fluides

    1994-06-01

    A review of hydrogen permeation barriers that can be applied to structural metals used in fusion power plants is presented. Both implanted and chemically available hydrogen isotopes must be controlled in fusion plants. The need for permeation barriers appears strongest in Li17-Pb blanket designs, although barriers also appear necessary for other blanket and coolant systems. Barriers that provide greater than a 1000 fold reduction in the permeation of structural metals are desired. In laboratory experiments, aluminide and titanium ceramic coatings provide permeation reduction factors, PRFS, from 1000 to over 100,000 with a wide range of scatter. The rate-controlling mechanism for hydrogen permeation through these barriers may be related to the number and type of defects in the barriers. Although these barriers appear robust and resistant to liquid metal corrosion, irradiation tests which simulate blanket environments result in very low PRFs in comparison to laboratory experiments, i.e., <150. It is anticipated from fundamental research activities that the REID enhancement of hydrogen diffusion in oxides may contribute to the lower permeation reduction factors during in-reactor experiments.

  11. A LOOK AT CULTURAL BARRIERS

    Directory of Open Access Journals (Sweden)

    Carmen A. VRÂNCEANU

    2015-06-01

    Full Text Available Nowadays the global market allows each individual to work in foreign countries. This fact is a great opportunity for business development, but also puts into light the problem of cultural barriers. Ineffective cross-cultural communication and collaboration can harm employees, customers, and other stakeholders. A company with employees from different cultures must acknowledge and understand these barriers in order to overcome them and to obtain the desired performance. The present study aims to expose the cultural barriers encountered by foreigners in a multinational company from Romania.

  12. Barriers in Concurrent Separation Logic

    Science.gov (United States)

    Hobor, Aquinas; Gherghina, Cristian

    We develop and prove sound a concurrent separation logic for Pthreads-style barriers. Although Pthreads barriers are widely used in systems, and separation logic is widely used for verification, there has not been any effort to combine the two. Unlike locks and critical sections, Pthreads barriers enable simultaneous resource redistribution between multiple threads and are inherently stateful, leading to significant complications in the design of the logic and its soundness proof. We show how our logic can be applied to a specific example program in a modular way. Our proofs are machine-checked in Coq.

  13. Topology optimization of two-dimensional elastic wave barriers

    DEFF Research Database (Denmark)

    Van Hoorickx, C.; Sigmund, Ole; Schevenels, M.

    2016-01-01

    Topology optimization is a method that optimally distributes material in a given design domain. In this paper, topology optimization is used to design two-dimensional wave barriers embedded in an elastic halfspace. First, harmonic vibration sources are considered, and stiffened material is insert...

  14. 30 CFR 75.819 - Motor-starter enclosures; barriers and interlocks.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Motor-starter enclosures; barriers and...-Voltage Distribution High-Voltage Longwalls § 75.819 Motor-starter enclosures; barriers and interlocks. Compartment separation and cover interlock switches for motor-starter enclosures must be maintained...

  15. Barriers and facilitators of sports in Dutch Paralympic athletes : An explorative study

    NARCIS (Netherlands)

    Jaarsma, E. A.; Geertzen, J. H. B.; de Jong, R.; Dijkstra, P. U.; Dekker, R.

    2014-01-01

    The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports

  16. ASYMPTOTIC THEORY FOR A RISK PROCESS WITH A HIGH DIVIDEND BARRIER

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A modified classical model with a dividend barrier is considered. It is shown that there is a simple approximation formula for the time of ruin when the level of dividend barrier is high and the claim sizes have a distribution that belongs to S(γ) with γ> 0.

  17. Barriers and facilitators of sports in Dutch Paralympic athletes : An explorative study

    NARCIS (Netherlands)

    Jaarsma, E. A.; Geertzen, J. H. B.; de Jong, R.; Dijkstra, P. U.; Dekker, R.

    2014-01-01

    The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports

  18. Comparing the Dimensions of Modern and Ancient Barrier Island Systems to Understand Controls on Preservation

    Science.gov (United States)

    Mulhern, J.; Johnson, C. L.; Stright, L.

    2015-12-01

    Commonly assumed to have low preservation potential, barrier islands are rarely interpreted in the rock record, and there is little consensus on the terminology and depositional models related to their interpretation. Prevalent on transgressive coastlines, the dimensions of modern barriers are used as analogs for the ancient; however, ancient examples are complicated by post-depositional processes, including thickening through amalgamation and removal by ravinement. Contrasting the dimensions of modern and ancient examples lends insight into the development and preservation of transgressive deposits, improving the ability to predict the size and distribution of barrier island sand bodies in the rock record as well as understanding the variables that control their architecture. Interpretation of barrier island deposits from the John Henry Member (Cretaceous Straight Cliffs Fm., Kaiparowits Plateau, southern Utah) motivated an investigation into both ancient and modern barrier islands. Traditional sequence stratigraphic models predict thin condensed deposition during transgression, not accounting for possible thick and laterally extensive accumulations of barrier island deposits. More recent models recognize the possible complexity and heterogeneity of transgressive deposits and the potential for barrier island accumulation. To better understand the relationship between modern and ancient barrier islands, the length (along strike), width (dip direction) and thickness (vertical) of >20 modern and >30 ancient barrier islands were compared. Ancient dimensions were gathered from the literature, while modern dimensions were aggregated from literature and a database of modern barrier islands currently being developed. Initial results suggest that ancient barrier island deposits record the motion of the shoreline during transgression. Ancient barriers are ~2-8 times wider and ~2-3 times thicker than modern islands. The dynamics of barrier island migration and sediment

  19. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Department of Resources — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  20. and use of barrier techniques

    African Journals Online (AJOL)

    Attitudes of Nigerian dentists towards hepatitis B vaccination and use of barrier techniques .... tine screening of only high-risk patients has been recommended.“ .... i337-1342. Sote EO. AIDS and infection Control: experiences, attitudes,.

  1. Barriers for recess physical activity

    DEFF Research Database (Denmark)

    Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper

    2014-01-01

    they would like to have more secluded areas added to the school playground, even in large schoolyards where lack of space was not a barrier. This aligned with girls' requests for more "hanging-out" facilities, whereas boys primarily wanted activity promoting facilities. CONCLUSION: Based on the results from......BACKGROUND: Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender....... This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews. RESULTS: The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys...

  2. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Department of Resources — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  3. Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  4. Guided tissue regeneration. Absorbable barriers.

    Science.gov (United States)

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  5. Ocean barrier layers' effect on tropical cyclone intensification.

    Science.gov (United States)

    Balaguru, Karthik; Chang, Ping; Saravanan, R; Leung, L Ruby; Xu, Zhao; Li, Mingkui; Hsieh, Jen-Shan

    2012-09-04

    Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.

  6. Nonlocal reflection by photonic barriers

    OpenAIRE

    Vetter, R. -M.; A. Haibel; Nimtz, G.

    2001-01-01

    The time behaviour of microwaves undergoing partial reflection by photonic barriers was measured in the time and in the frequency domain. It was observed that unlike the duration of partial reflection by dielectric layers, the measured reflection duration of barriers is independent of their length. The experimental results point to a nonlocal behaviour of evanescent modes at least over a distance of some ten wavelengths. Evanescent modes correspond to photonic tunnelling in quantum mechanics.

  7. Schooling Inequality and Language Barriers

    OpenAIRE

    Parker, Susan W.; Rubalcava, Luis; Teruel, Graciela

    2005-01-01

    This article estimates the impact of language barriers on school achievement and the potential ameliorating role of bilingual education. Using large household data sets from poor rural communities in Mexico, we find that parental language (failure to speak Spanish) represents an important barrier to the schooling of indigenous children. We provide an empirical test suggesting that this largely reflects parental human capital related to culture/language, rather than unobserved wealth effects. ...

  8. Economic alternatives for containment barriers

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, P.J.; Jasperse, B.H.; Fisher, M.J. [Geo-Con, Inc., Monroeville, PA (United States)

    1997-12-31

    Fixation, barriers, and containment of existing landfills and other disposal areas are often performed by insitu auger type soil mixing and jet grouting. Cement or other chemical reagents are mixed with soil to form both vertical and horizontal barriers. Immobilization of contaminants can be economically achieved by mixing soil and the contaminants with reagents that solidify or stabilize the contaminated area. Developed in Japan, and relatively new to the United States, the first large scale application was for a vertical barrier at the Jackson Lake Dam project in 1986. This technology has grown in both the civil and environmental field since. The paper describes current United States practice for Deep Soil Mixing (over 12 meters in depth), and Shallow Soil Mixing for vertical barriers and stabilization/solidification, and Jet Grouting for horizontal and vertical barriers. Creating very low permeability barriers at depth with minimal surface return often makes these techniques economical when compared to slurry trenches. The paper will discuss equipment, materials, soil and strength parameters, and quality control.

  9. Summer bird use of a barrier island near Prudhoe Bay, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The number and distribution of birds near a barrier island west of Prudhoe Bay, Alaska, were recorded during the summer of 1972. Eiders fed and rested in the open...

  10. Filaggrin and Skin Barrier Function.

    Science.gov (United States)

    Kezic, Sanja; Jakasa, Ivone

    2016-01-01

    The skin barrier function is greatly dependent on the structure and composition of the uppermost layer of the epidermis, the stratum corneum (SC), which is made up of flattened anucleated cells surrounded by highly organized and continuous lipid matrix. The interior of the corneocytes consists mainly of keratin filaments aggregated by filaggrin (FLG) protein. Next, together with several other proteins, FLG is cross-linked into a mechanically robust cornified cell envelope providing a scaffold for the extracellular lipid matrix. In addition to its role for the SC structural and mechanical integrity, FLG degradation products account in part for the water-holding capacity and maintenance of acidic pH of the SC, both crucial for the epidermal barrier homoeostasis by regulating activity of multiple enzymes that control desquamation, lipid synthesis and inflammation. The major determinant of FLG expression in the skin are loss-of-function mutations in FLG, the strongest genetic risk factor for atopic dermatitis (AD), an inflammatory skin disease characterized by a reduced skin barrier function. The prevalence of FLG mutations varies greatly among different populations and ranges from about 10% in Northern Europeans to less than 1% in the African populations. An impaired skin barrier facilitates absorption of potentially hazardous chemicals, which might cause adverse effects in the skin, such as contact dermatitis, or systemic toxicity after their passage into blood. In another direction, a leaky epidermal barrier will lead to enhanced loss of water from the skin. A recent study has shown that even subtle increase in epidermal water loss in newborns increases the risk for AD. Although there are multiple modes of action by which FLG might affect skin barrier it is still unclear whether and how FLG deficiency leads to the reduced skin barrier function. This chapter summarizes the current knowledge in this field obtained from clinical studies, and animal and in vitro models

  11. Exploring the stability of super heavy elements: First Measurement of the Fission Barrier of 254No

    Directory of Open Access Journals (Sweden)

    Henning G.

    2014-03-01

    Full Text Available The gamma-ray multiplicity and total energy emitted by the heavy nucleus 254No have been measured at 2 different beam energies. From these measurements, the initial distributions of spin I and excitation energy E∗ of 254No were constructed. The distributions display a saturation in excitation energy, which allows a direct determination of the fission barrier. 254No is the heaviest shell-stabilized nucleus with a measured fission barrier.

  12. Diabetes and diet: Managing dietary barriers.

    NARCIS (Netherlands)

    Friele, R.D.

    1989-01-01

    This thesis reports on the barriers diabetic patients experience with their diet, and the ways they cope with these barriers. A dietary barrier is a hinderance to a person's well-being, induced by being advised a diet. First inventories were made of possible dietary barriers and ways of coping with

  13. Approach to Quantum Kramers' Equation and Barrier Crossing Dynamics

    CERN Document Server

    Banerjee, Dhruba; Banik, S K; Ray, D S; Banerjee, Dhruba; Bag, Bidhan Chandra; Banik, Suman Kumar; Ray, Deb Shankar

    2002-01-01

    We have presented a simple approach to quantum theory of Brownian motion and barrier crossing dynamics. Based on an initial coherent state representation of bath oscillators and an equilibrium canonical distribution of quantum mechanical mean values of their co-ordinates and momenta we have derived a $c$-number generalized quantum Langevin equation. The approach allows us to implement the method of classical non-Markovian Brownian motion to realize an exact generalized non-Markovian quantum Kramers' equation. The equation is valid for arbitrary temperature and friction. We have solved this equation in the spatial diffusion-limited regime to derive quantum Kramers' rate of barrier crossing and analyze its variation as a function of temperature and friction. While almost all the earlier theories rest on quasi-probability distribution functions (like Wigner function) and path integral methods, the present work is based on {\\it true probability distribution functions} and is independent of path integral technique...

  14. Cytokines and the Skin Barrier

    Directory of Open Access Journals (Sweden)

    Jens Malte Baron

    2013-03-01

    Full Text Available The skin is the largest organ of the human body and builds a barrier to protect us from the harmful environment and also from unregulated loss of water. Keratinocytes form the skin barrier by undergoing a highly complex differentiation process that involves changing their morphology and structural integrity, a process referred to as cornification. Alterations in the epidermal cornification process affect the formation of the skin barrier. Typically, this results in a disturbed barrier, which allows the entry of substances into the skin that are immunologically reactive. This contributes to and promotes inflammatory processes in the skin but also affects other organs. In many common skin diseases, including atopic dermatitis and psoriasis, a defect in the formation of the skin barrier is observed. In these diseases the cytokine composition within the skin is different compared to normal human skin. This is the result of resident skin cells that produce cytokines, but also because additional immune cells are recruited. Many of the cytokines found in defective skin are able to influence various processes of differentiation and cornification. Here we summarize the current knowledge on cytokines and their functions in healthy skin and their contributions to inflammatory skin diseases.

  15. Cylindrical air flow reversal barrier

    Energy Technology Data Exchange (ETDEWEB)

    Woznica, C.; Rodziewicz, M.

    1988-06-01

    Describes an innovative design introduced in the ZMP mine in Zory for quick reversal of ventilation air flow. Geologic mining conditions at the 705 m deep horizon, where the barrier was built, are described. According to the design used until now, a reversal system consisted of safety barriers, ventilation air locks, a ventilation bridge and stopping needed in case of a fire when air flow direction must be reversed. Nine air locks and an expensive concrete ventilation bridge were needed and the air locks had to be operated at 8 points of the region to effect reversal. The new design consists of a 2-storey cylindrical barrier which also fulfills the function of a ventilation bridge. It can be manually or remotely operated by a mechanical or pneumatic system. Tests showed that the new barrier permits immediate air flow reversal while retaining 60% of the original air, which is important in the case of fire and methane hazards. It permits improved seam panelling and splitting of pillars and brings an economy of about 40 million zlotys in construction cost. Design and operation of the barrier is illustrated and ventilation air circulation is explained. 7 figs.

  16. Skin Barrier Function and Allergens

    DEFF Research Database (Denmark)

    Engebretsen, Kristiane Aasen; Thyssen, Jacob Pontoppidan

    2016-01-01

    The skin is an important barrier protecting us from mechanical insults, microorganisms, chemicals and allergens, but, importantly, also reducing water loss. A common hallmark for many dermatoses is a compromised skin barrier function, and one could suspect an elevated risk of contact sensitization...... and skin barrier status. Psoriasis has traditionally been regarded a Th1-dominated disease, but the discovery of Th17 cells and IL-17 provides new and interesting information regarding the pathogenesis of the disease. Research suggests an inverse relationship between psoriasis and CA, possibly due......) and Th2 (AD) have been proposed as an explanation. Finally, there is convincing evidence that exposure to irritants increases the risk of CS, and patients with ICD are, therefore, at great risk of developing CA. Skin irritation leads to the release of IL-1 and TNF-α, which affects the function of antigen...

  17. 鄂尔多斯盆地下奥陶统马家沟组障壁潟湖沉积相模式及有利储层分布规律%Barrier- Lagoon Sedimentary Model and Reservoir Distribution Regularity of Lower-Ordovician Majiagou Formation in Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    周进高; 张帆; 郭庆新; 邓红婴; 辛勇光

    2011-01-01

    model- barrier-lagoon sedimentary model of Majiagou Formation is developed. The model includes three phases during transgression to high sea level (phase Ⅰ ), carbonate deposits in broad barrier-lagoon, and mixed carbonate / evaporate succession in concentrated lagoon during regression ( phase Ⅱ ), and anhydrite and salt in saline during low sea level ( phase Ⅲ ).And two main types of carbonate reservoir including the dolomite reservoir in relation to karstification and the crystallization dolomite reservoir in connection with dolomitization are discovered in this paper. The authors further analyze the carbonate reservoir distribution law within the mentioned model, conclude that beach-flat of platform edge of the model(phase Ⅰ )and lagoon margin flat of phase Ⅱ are favorable for reservoir growth and point out that the reservoir of Majiagou Formation is karst type and is mainly distributed on the top of Ma5, Ma3 and Ma1 Formation. Anhydrite and salt of phase Ⅲ are important seal rock.%依据鄂尔多斯盆地古构造古地理背景、古水动力以及古气候条件,结合单井沉积相分析建立了马家沟组障壁潟湖沉积相模式,该模式分三个阶段即与海侵期相对应的以灰岩沉积为主的障壁潟湖沉积阶段(阶段Ⅰ)、与海退相对应的以灰岩夹蒸发岩沉积为主的障壁咸化潟湖沉积阶段(阶段Ⅱ)和与低海平面期对应的以膏岩盐沉积为主的障壁膏盐湖沉积阶段(阶段Ⅲ).文章进一步分析并总结了在上述模式下各阶段储层的发育规律,认为阶段Ⅰ中的障壁滩相和阶段Ⅱ中的障壁滩及潟湖边缘坪有利于储层的发育,并指出了马家沟组储层主要为岩溶型储层,分布于马一、马三和马五的顶部.

  18. Sound propagation over curved barriers

    Science.gov (United States)

    Pierce, Allan D.; Main, Geoffrey L.; Kearns, James A.; Hsieh, H.-A.

    1986-01-01

    Wide barriers with curved tops are studied with emphasis placed on circumstances whereby the local radius of curvature R of the barrier is continuous along the surface and is large compared to a wavelength. Results analogous to those given by Hayek et al. (1978) are reviewed and extended to cases where the radius of curvature and the surface impedance may vary with position. Circumstances not easily interpreted within the framework of the model proposed by Keller (1956) and Hayek et al. are also considered.

  19. The Solution to Green Barrier

    Institute of Scientific and Technical Information of China (English)

    Cui Yan

    2009-01-01

    @@ The recovery process of world economy is rough and full of twists and turns.Especially the trade protectionism,having reemerged under the mask of"green barrier",is making a great impact on the slowly recovering world economy and trade.Then,what are the characteristics of trade barriers in the post-crisis era?Where is the outlet of Chinese manufacturing industry?With these questions,ourreporter interviewed Professor Zhou Shijian,Standing Director to China Association of International Trade and Senior Researcher to SINO-US Relationship Research Centre of Tsinghua University.

  20. Development of the Barriers to Error Disclosure Assessment Tool.

    Science.gov (United States)

    Welsh, Darlene; Zephyr, Dominique; Pfeifle, Andrea L; Carr, Douglas E; Fink, Joseph L; Jones, Mandy

    2017-06-30

    An interprofessional group of health colleges' faculty created and piloted the Barriers to Error Disclosure Assessment tool as an instrument to measure barriers to medical error disclosure among health care providers. A review of the literature guided the creation of items describing influences on the decision to disclose a medical error. Local and national experts in error disclosure used a modified Delphi process to gain consensus on the items included in the pilot. After receiving university institutional review board approval, researchers distributed the tool to a convenience sample of physicians (n = 19), pharmacists (n = 20), and nurses (n = 20) from an academic medical center. Means and SDs were used to describe the sample. Intraclass correlation coefficients were used to examine test-retest correspondence between the continuous items on the scale. Factor analysis with varimax rotation was used to determine factor loadings and examine internal consistency reliability. Cronbach α coefficients were calculated during initial and subsequent administrations to assess test-retest reliability. After omitting 2 items with intraclass correlation coefficient of less than 0.40, intraclass correlation coefficients ranged from 0.43 to 0.70, indicating fair to good test-retest correspondence between the continuous items on the final draft. Factor analysis revealed the following factors during the initial administration: confidence and knowledge barriers, institutional barriers, psychological barriers, and financial concern barriers to medical error disclosure. α Coefficients of 0.85 to 0.93 at time 1 and 0.82 to 0.95 at time 2 supported test-retest reliability. The final version of the 31-item tool can be used to measure perceptions about abilities for disclosing, impressions regarding institutional policies and climate, and specific barriers that inhibit disclosure by health care providers. Preliminary evidence supports the tool's validity and reliability for measuring

  1. Systems study on engineered barriers: barrier performance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

    1980-09-01

    A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed.

  2. Collective spectra along the fission barrier

    Directory of Open Access Journals (Sweden)

    Pigni M. T.

    2012-12-01

    Full Text Available Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states and in the intermediate wells (superdeformed and hyperdeformed states play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster configurations in a dynamical way, permitting exchange of upper–shell nucleons between clusters. The impact of theoretical spectra on neutron–induced fission cross sections and, in combination with an improved version of the scission–point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  3. Plastic Schottky barrier solar cells

    Science.gov (United States)

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

  4. Seasonal breaching of coastal barriers

    NARCIS (Netherlands)

    Tuan, Thieu Quang

    2007-01-01

    Natural or unintended breaching can be catastrophic, causing loss of human lives and damage to infrastructures, buildings and natural habitats. Quantitative understand-ing of coastal barrier breaching is therefore of great importance to vulnerability as-sessment of protection works as well as to

  5. Functional barriers: Properties and evaluation

    NARCIS (Netherlands)

    Feigenbaum, A.; Dole, P.; Aucejo, S.; Dainelli, D.; Cruz Garcia, C. de la; Hankemeier, T.; N'Gono, Y.; Papaspyrides, C.D.; Paseiro, P.; Pastorelli, S.; Pavlidou, S.; Pennarun, P.Y.; Saillard, P.; Vidal, L.; Vitrac, O.; Voulzatis, Y.

    2005-01-01

    Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of t

  6. Communication Barriers in Distance Education

    Science.gov (United States)

    Isman, Aytekin; Dabaj, Fahme; Altinay, Fahriye; Altinay, Zehra

    2003-01-01

    Communication is a key concept as being the major tool for people in order to satisfy their needs. It is an activity which refers as process and effective communication requires qualified communication with the elimination of communication barriers. As it is known, distance education is a new trend by following contemporary facilities and tools…

  7. FX barriers with smile dynamics

    NARCIS (Netherlands)

    Baker, Glyn; Beneder, Reimer; Zilber, Alex

    2004-01-01

    Our mandate in this work has been to isolate the features of smile consistent models that are most relevant to the pricing of barrier options. We consider the two classical approaches of stochastic and (parametric) local volatility. Although neither has been particularly successful in practice their

  8. Planar doped barrier subharmonic mixers

    Science.gov (United States)

    Lee, T. H.; East, J. R.; Haddad, G. I.

    1992-01-01

    The Planar Doped Barrier (PDB) diode is a device consisting of a p(+) doping spike between two intrinsic layers and n(+) ohmic contacts. This device has the advantages of controllable barrier height, diode capacitance and forward to reverse current ratio. A symmetrically designed PDB has an anti-symmetric current vs. voltage characteristic and is ideal for use as millimeter wave subharmonic mixers. We have fabricated such devices with barrier heights of 0.3, 0.5 and 0.7 volts from GaAs and InGaAs using a multijunction honeycomb structure with junction diameters between one and ten microns. Initial RF measurements are encouraging. The 0.7 volt barrier height 4 micron GaAs devices were tested as subharmonic mixers at 202 GHz with an IF frequency of 1 GHz and had 18 dB of conversion loss. The estimated mismatch loss was 7 dB and was due to higher diode capacitance. The LO frequency was 100.5 GHz and the pump power was 8 mW.

  9. Barrier/Cu contact resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Reid, J.S.; Nicolet, M.A. [California Inst. of Tech., Pasadena, CA (United States); Angyal, M.S.; Lilienfeld, D.; Shacham-Diamand, Y. [Cornell Univ., Ithaca, NY (United States); Smith, P.M. [Sandia National Labs., Albuquerque, NM (United States)

    1995-10-17

    The specific contact resistivity of Cu with ({alpha} + {beta})-Ta, TiN, {alpha}-W, and amorphous-Ta{sub 36}Si{sub 14}N{sub 50} barrier films is measured using a novel four-point-probe approach. Geometrically, the test structures consist of colinear sets of W-plugs to act as current and voltage probes that contact the bottom of a planar Cu/barrier/Cu stack. Underlying Al interconnects link the plugs to the current source and voltmeter. The center-to-center distance of the probes ranges from 3 to 200 {micro}m. Using a relation developed by Vu et al., a contact resistivity of roughly 7 {times} 10{sup {minus}9} {Omega} cm{sup 2} is obtained for all tested barrier/Cu combinations. By reflective-mode small-angle X-ray scattering, the similarity in contact resistivity among the barrier films may be related to interfacial impurities absorbed from the deposition process.

  10. Reliability enhancement due to in-situ post-oxidation of sputtered MgO barrier in double MgO barrier magnetic tunnel junction

    Science.gov (United States)

    Yoshida, Chikako; Noshiro, Hideyuki; Yamazaki, Yuichi; Sugii, Toshihiro

    2017-06-01

    We have investigated the effects of in-situ post-oxidation (PO) of a sputtered MgO barrier in a double-MgO-barrier magnetic tunnel junction (MTJ) and found that the short error rate was significantly reduced, the magnetoresistance (MR) ratio was increased approximately 18%, and the endurance lifetime was extend. In addition, we found that the distribution of breakdown number (a measure of endurance) exhibits trimodal characteristics, which indicates competition between extrinsic and intrinsic failures. This improvement in reliability might be related to the suppression of Fe and Co diffusion to the MgO barrier, as revealed by electron energy-loss spectroscopy (EELS) analysis.

  11. Barriers to improvements in energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the ``barriers`` literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  12. Barriers to improvements in energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the barriers'' literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  13. An exploration study to detect important barriers for knowledge management

    Directory of Open Access Journals (Sweden)

    Jalil Ghafourian

    2014-01-01

    Full Text Available This paper presents an empirical investigation to find the important factors influencing implementation of knowledge management in revenue agencies in Iran. The proposed study designs a questionnaire and distributes it among some experts and, using principal component analysis, the study detects important barriers for knowledge management implications. The study selects 170 people from 880 regular employees who work for revenue agency and distributes the questionnaire designed in Likert scale. Cronbach alpha has been determined as 0.70, which is well above the minimum acceptable level. In terms of knowledge management, the study determines six factors including support for creativity and innovation, knowledge sharing, trust, employee promotion plan, mission and training programs and they represent 66.57% of the described factors. In addition, in terms of barriers, job security, cultural issues, individual differences, infrastructure, organizational structure and lack of vision are the most important issues representing 61.98% of the factors.

  14. Barriers to Implementation of Evidence Based Practice in Zahedan Teaching Hospitals, Iran, 2014

    Directory of Open Access Journals (Sweden)

    Mohammad Khammarnia

    2015-01-01

    Full Text Available This study aimed to determine the barriers to implementation of EBP among nurses. This cross-sectional study was conducted in Zahedan City, South East of Iran, in 2014. The questionnaire of barriers to implementation of EBP consists of 27 statements which was distributed among 280 nurses. More than half of the participants agreed that 56% and 57% of barriers to implementation of evidence based practice are related to organizational and individual aspects, respectively. Participants identified barriers at organizational level included the lack of human resources (78.3%, lack of internet access at work (72.2%, and heavy workload (70.0%. Barrier at individual level included lack of time to read literature (83.7%, lack of ability to work with computer (68.8%, and insufficient proficiency in English language (62.0%. Age, educational level, job experience, and employment status were associated with organizational barriers to implementation of EBP. At the individual level only education was associated with barriers to implementation of EBP. Barriers to implementation of EBP occur at both individual and organizational levels. The indicator of quality in nursing practice is EBP. Hence, familiarity with EBP is recommended for Iranian nurses. In addition, knowledge of barriers will help health care system and policy makers to provide a culture of EBP.

  15. Autostereoscopic display concept with time-sequential wavelength-selective filter-barrier

    Science.gov (United States)

    Jurk, Silvio; Kuhlmey, Mathias; Bartmann, Roland; Duckstein, Bernd; de la Barré, René

    2016-03-01

    A spatially multiplexed autostereoscopic 3D display design with a strip barrier consisting of RGB-color filters is presented. The wavelength selective filter barrier emits the light from a display area larger than that of common autostereoscopic barrier displays. However, such construction is still used rather rarely. The time sequential operation mode is a supplemental option. Wavelength selective filter barrier arrangements exhibit characteristics different from common barrier displays with similar barrier pitch and ascent. In particular these constructions show strong angular luminance dependency under barrier inclination specified by correspondent slant angle. In time sequential implementation it is important to avoid that quick eye or eyelid movement lead to visible color artifacts. Those circumstances limit the possibility to find well working and usable display designs superior to usual barrier displays. The newly introduced design is usable as a multi user display as well as a single user system with user adaptive control. In case of tracked single user mode the adaption in x-z-direction is continuously. The design has been modelled with simulation software developed for that purpose. The modelling of wavelength-selective barriers was used to calculate the light ray distribution properties of that arrangement. For the experimental verification of the image separation and evaluation of image quality, commercially available display components were combined for a display demonstrator.

  16. Barriers and facilitators of sports in Dutch Paralympic athletes: An explorative study.

    Science.gov (United States)

    Jaarsma, E A; Geertzen, J H B; de Jong, R; Dijkstra, P U; Dekker, R

    2014-10-01

    The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports participation. The International Classification of Functioning, Disability and Health model and theory of planned behavior were used to respectively categorize the results in environmental and personal factors, and attitude, subjective norm and perceived behavioral control. Seventy-six Dutch Paralympic athletes completed the questionnaire (51% response rate). Barriers and facilitators experienced by ambulant and wheelchair athletes were compared. Most frequently mentioned personal barrier was dependency of others (22%), while most frequently mentioned environmental barrier was lack of sports facilities (30%). Wheelchair athletes mentioned more barriers (median = 3, interquartile range: 0.5-6), than ambulant athletes (median = 1.0,interquartile range:0.0-3.0, P = 0.023). One-third of the athletes did not experience any barriers. Most frequently mentioned personal facilitators to initiate sports participation were fun (78%), health (61%), and competition (53%). Most frequently mentioned environmental facilitator was social support (40%). This study indicated that barriers of sport were mostly environmental, while facilitators were usually personal factors. Attitude and subjective norm were considered the most important components for intention to participation in sports. The facilitators outweighed the barriers and kept the athletes being active in sports.

  17. Patient advocacy: barriers and facilitators

    Directory of Open Access Journals (Sweden)

    Nikravesh Mansoure

    2006-03-01

    Full Text Available Abstract Background During the two recent decades, advocacy has been a topic of much debate in the nursing profession. Although advocacy has embraced a crucial role for nurses, its extent is often limited in practice. While a variety of studies have been generated all over the world, barriers and facilitators in the patient advocacy have not been completely identified. This article presents the findings of a study exploring the barriers and facilitators influencing the role of advocacy among Iranian nurses. Method This study was conducted by grounded theory method. Participants were 24 Iranian registered nurses working in a large university hospital in Tehran, Iran. Semi-structured interviews were used for data collection. All interviews were transcribed verbatim and simultaneously Constant comparative analysis was used according to the Strauss and Corbin method. Results Through data analysis, several main themes emerged to describe the factors that hindered or facilitated patient advocacy. Nurses in this study identified powerlessness, lack of support, law, code of ethics and motivation, limited communication, physicians leading, risk of advocacy, royalty to peers, and insufficient time to interact with patients and families as barriers to advocacy. As for factors that facilitated nurses to act as a patient advocate, it was found that the nature of nurse-patient relationship, recognizing patients' needs, nurses' responsibility, physician as a colleague, and nurses' knowledge and skills could be influential in adopting the advocacy role. Conclusion Participants believed that in this context taking an advocacy role is difficult for nurses due to the barriers mentioned. Therefore, they make decisions and act as a patient's advocate in any situation concerning patient needs and status of barriers and facilitators. In most cases, they can not act at an optimal level; instead they accept only what they can do, which we called 'limited advocacy' in

  18. Dielectric barrier discharges applied for optical spectrometry

    Science.gov (United States)

    Brandt, S.; Schütz, A.; Klute, F. D.; Kratzer, J.; Franzke, J.

    2016-09-01

    The present review reflects the importance of dielectric barrier discharges for optical spectrometric detection in analytical chemistry. In contrast to usual discharges with a direct current the electrodes are separated by at least one dielectric barrier. There are two main features of the dielectric barrier discharges: they can serve as dissociation and excitation devices as well as ionization sources, respectively. This article portrays various application fields of dielectric barrier discharges in analytical chemistry used for elemental and molecular detection with optical spectrometry.

  19. Penetration through the Skin Barrier

    DEFF Research Database (Denmark)

    Nielsen, Jesper Bo; Benfeldt, Eva; Holmgaard, Rikke

    2016-01-01

    . During recent decades, the latter has received increased attention as a route for intentionally delivering drugs to patients. This has stimulated research in methods for sampling, measuring and predicting percutaneous penetration. Previous chapters have described how different endogenous, genetic...... and exogenous factors may affect barrier characteristics. The present chapter introduces the theory for barrier penetration (Fick's law), and describes and discusses different methods for measuring the kinetics of percutaneous penetration of chemicals, including in vitro methods (static and flow......-through diffusion cells) as well as in vivo methods (microdialysis and microperfusion). Then follows a discussion with examples of how different characteristics of the skin (age, site and integrity) and of the penetrants (size, solubility, ionization, logPow and vehicles) affect the kinetics of percutaneous...

  20. Security barriers with automated reconnaissance

    Science.gov (United States)

    McLaughlin, James O; Baird, Adam D; Tullis, Barclay J; Nolte, Roger Allen

    2015-04-07

    An intrusion delaying barrier includes primary and secondary physical structures and can be instrumented with multiple sensors incorporated into an electronic monitoring and alarm system. Such an instrumented intrusion delaying barrier may be used as a perimeter intrusion defense and assessment system (PIDAS). Problems with not providing effective delay to breaches by intentional intruders and/or terrorists who would otherwise evade detection are solved by attaching the secondary structures to the primary structure, and attaching at least some of the sensors to the secondary structures. By having multiple sensors of various types physically interconnected serves to enable sensors on different parts of the overall structure to respond to common disturbances and thereby provide effective corroboration that a disturbance is not merely a nuisance or false alarm. Use of a machine learning network such as a neural network exploits such corroboration.

  1. Article Including Environmental Barrier Coating System

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2015-01-01

    An enhanced environmental barrier coating for a silicon containing substrate. The enhanced barrier coating may include a bond coat doped with at least one of an alkali metal oxide and an alkali earth metal oxide. The enhanced barrier coating may include a composite mullite bond coat including BSAS and another distinct second phase oxide applied over said surface.

  2. Barrierer for realisering af energibesparelser i bygninger

    DEFF Research Database (Denmark)

    Jensen, Ole Michael

    2004-01-01

    For få bygningsejere går i gang med at investere i energibesparelser. Årsagen tilskrives en række barrierer, som møder den enkelte bygningsejer, når denne vil i gang med at foretage energirenoveringer. Men ikke alle barrierer handler om barrierer i traditionel forstand, men om tilbageholdenhed. Den...

  3. Market barriers to welfare product innovations

    NARCIS (Netherlands)

    Binnekamp, M.H.A.; Ingenbleek, P.T.M.

    2006-01-01

    New products that are based on higher animal welfare standards encounter several barriers on the road to market acceptance. The authors focus on the Dutch poultry sector and distinguish between retailer and consumer barriers. Retailer barriers include the powerful position of retailers, the price co

  4. Design of the Muong Chuoi Barrier

    NARCIS (Netherlands)

    Van Vliegen, K.; Van Oorschot, N.; Meinen, N.; Van Dijk, S.; Reimert, Z.

    2013-01-01

    Ho Chi Minh City has to deal with severe flooding in the rainy season. To prevent the city from this flooding, MARD set up plan 1547. The main idea of the plan is to build a ring dike around HCMC in combination with several movable tidal barriers. One of these barriers is the Muong Chuoi Barrier. I

  5. Barriers to Mammography among Inadequately Screened Women

    Science.gov (United States)

    Stoll, Carolyn R. T.; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V.; Jackson, Sherrill; Politi, Mary C.

    2015-01-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography…

  6. Market barriers to welfare product innovations

    NARCIS (Netherlands)

    Binnekamp, M.H.A.; Ingenbleek, P.T.M.

    2006-01-01

    New products that are based on higher animal welfare standards encounter several barriers on the road to market acceptance. The authors focus on the Dutch poultry sector and distinguish between retailer and consumer barriers. Retailer barriers include the powerful position of retailers, the price

  7. Flexible pile thermal barrier insulator

    Science.gov (United States)

    Anderson, G. E.; Fell, D. M.; Tesinsky, J. S. (Inventor)

    1978-01-01

    A flexible pile thermal barrier insulator included a plurality of upstanding pile yarns. A generally planar backing section supported the upstanding pile yarns. The backing section included a plurality of filler yarns forming a mesh in a first direction. A plurality of warp yarns were looped around said filler yarns and pile yarns in the backing section and formed a mesh in a second direction. A binder prevented separation of the yarns in the backing section.

  8. Overcome barriers to career success

    Energy Technology Data Exchange (ETDEWEB)

    Raudsepp, E.

    1983-04-01

    A test is given to determine if an engineer suffers from one of the three barriers to technical success: fear of success, fear of failure, or perfectionism. As in most such tests, the middle way is best. Successful engineers know that perfection cannot be attained, that they don't have time to worry about failure or success, and that by aiming and perservering in doing things well, success can be achieved.

  9. Removing Barriers to Interdisciplinary Research

    CERN Document Server

    Jacobs, Naomi

    2010-01-01

    A significant amount of high-impact contemporary scientific research occurs where biology, computer science, engineering and chemistry converge. Although programmes have been put in place to support such work, the complex dynamics of interdisciplinarity are still poorly understood. In this paper we interrogate the nature of interdisciplinary research and how we might measure its "success", identify potential barriers to its implementation, and suggest possible mechanisms for removing these impediments.

  10. Wet Work and Barrier Function.

    Science.gov (United States)

    Fartasch, Manigé

    2016-01-01

    Wet work defined as unprotected exposure to humid environments/water; high frequencies of hand washing procedures or prolonged glove occlusion is believed to cause irritant contact dermatitis in a variety of occupations. This review considers the recent studies on wet-work exposure and focuses on its influence on barrier function. There are different methods to study the effect of wet work on barrier function. On the one hand, occupational cohorts at risk can be monitored prospectively by skin bioengineering technology and clinical visual scoring systems; on the other hand, experimental test procedures with defined application of water, occlusion and detergents are performed in healthy volunteers. Both epidemiological studies and the results of experimental procedures are compared and discussed. A variety of epidemiological studies analyze occupational cohorts at risk. The measurement of transepidermal water loss, an indicator of the integrity of the epidermal barrier, and clinical inspection of the skin have shown that especially the frequencies of hand washing and water contact/contact to aqueous mixtures seem to be the main factors for the occurrence of barrier alterations. On the other hand, in a single cross-sectional study, prolonged glove wearing (e.g. occlusion for 6 h per shift in clean-room workers) without exposure to additional hazardous substances seemed not to affect the skin negatively. But regarding the effect of occlusion, there is experimental evidence that previously occluded skin challenged with sodium lauryl sulfate leads to an increased susceptibility to the irritant with an aggravation of the irritant reaction. These findings might have relevance for the real-life situation in so far as after occupational glove wearing, the skin is more susceptible to potential hazards to the skin even during leisure hours.

  11. On Optimality of the Barrier Strategy for the Classical Risk Model with Interest

    Institute of Scientific and Technical Information of China (English)

    Ying Fang; Rong Wu

    2011-01-01

    In this paper, we consider the optimal dividend problem for a classical risk model with a constant force of interest. For such a risk model, a sufficient condition under which a barrier strategy is the optimal strategy is presented for general claim distributions. When claim sizes are exponentially distributed, it is shown that the optimal dividend policy is a barrier strategy and the maximal dividend-value function is a concave function. Finally, some known results relating to the distribution of aggregate dividends before ruin are extended.

  12. Key Barriers to the Implementation of Solar Energy in Nigeria: A Critical Analysis

    Science.gov (United States)

    Abdullahi, D.; Suresh, S.; Renukappa, S.; Oloke, D.

    2017-08-01

    Nigeria, potentially, has abundant sunshine throughout the year, making it full thirst for solar energy generation. Even though, the country’s solar energy projects have not realised a fair result over the years, due to many barriers associated with initiatives implementation. Therefore, the entire power sector remains incapacitated to generate, transmit and distribute a clean, affordable and sustainable energy to assist economic growth. The research integrated five African counterpart’s solar energy initiatives, barriers, policies and strategies adopted as a lesson learned to Nigeria. Inadequate solar initiative’s research, lack of technological know-how, short-term policies, lack of awareness and political instability are the major barriers that made the implementation of solar initiatives almost impossible in Nigeria. The shock of the barriers therefore, constitutes a major negative contribution to the crippling of the power sector in the state. Future research will concentrate on initiatives for mitigating solar and other renewable energy barriers.

  13. Reactive barriers: hydraulic performance and design enhancements.

    Science.gov (United States)

    Painter, B D M

    2004-01-01

    The remediation of contaminated ground water is a multibillion-dollar global industry. Permeable reactive barriers (PRBs) are one of the leading technologies being developed in the search for alternatives to the pump-and-treat method. Improving the hydraulic performance of these PRBs is an important part of maximizing their potential to the industry. Optimization of the hydraulic performance of a PRB can be defined in terms of finding the balance between capture, residence time, and PRB longevity that produces a minimum-cost acceptable design. Three-dimensional particle tracking was used to estimate capture zone and residence time distributions. Volumetric flow analysis was used for estimation of flow distribution across a PRB and in the identification of flow regimes that may affect the permeability or reactivity of portions of the PRB over time. Capture zone measurements extended below the base of partially penetrating PRBs and were measured upgradient from the portion of aquifer influenced by PRB emplacement. Hydraulic performance analysis of standard PRB designs confirmed previously presented research that identified the potential for significant variation in residence time and capture zone. These variations can result in the need to oversize the PRB to ensure that downgradient contaminant concentrations do not exceed imposed standards. The most useful PRB design enhancements for controlling residence time and capture variation were found to be customized downgradient gate faces, velocity equalization walls, deeper emplacement of the funnel than the gate, and careful manipulation of the hydraulic conductivity ratio between the gate and the aquifer.

  14. Assessment of sodium conductor distribution cable

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    The study assesses the barriers and incentives for using sodium conductor distribution cable. The assessment considers environmental, safety, energy conservation, electrical performance and economic factors. Along with all of these factors considered in the assessment, the sodium distribution cable system is compared to the present day alternative - an aluminum conductor system. (TFD)

  15. Perceived Sodium Reduction Barriers Among Patients with Chronic Kidney Disease: Which Barriers Are Important and Which Patients Experience Barriers?

    Science.gov (United States)

    Meuleman, Yvette; Hoekstra, Tiny; Dekker, Friedo W; van der Boog, Paul J M; van Dijk, Sandra

    2017-09-08

    The purposes of this study were to assess the importance of perceived sodium reduction barriers among patients with chronic kidney disease (CKD) and identify associated sociodemographic, clinical, and psychosocial factors. A total of 156 patients with CKD completed a questionnaire assessing sodium reduction barriers (18 self-formulated items), depressive symptoms (Beck Depression Inventory), perceived autonomy support (Modified Health Care Climate Questionnaire), and self-efficacy (Partners in Health Questionnaire). Factor analysis was used to identify barrier domains. Correlation coefficients were computed to examine relationships between barrier domains and patient characteristics. Nine barrier domains were identified. Barriers perceived as important were as follows: high sodium content in products, lack of sodium feedback, lack of goal setting and discussing strategies for sodium reduction, and not experiencing CKD-related symptoms (mean scores > 3.0 on 5-point scales, ranging from 1 'no barrier' to 5 'very important barrier'). Other barriers (knowledge, attitude, coping skills when eating out, and professional support) were rated as moderately important (rated around midpoint), and the barrier 'intrinsic motivation' was rated as somewhat important (mean score = 1.9). Sodium reduction barrier domains were not associated with gender and kidney function, but were associated with age, level of education, number of comorbidities, perceived autonomy support, depressive symptoms, and self-efficacy (range r = 0.17-0.35). Patients with lower self-efficacy and perceived autonomy support scores experienced most sodium reduction barriers. Patients with CKD experience multiple important sodium reduction barriers and could benefit from support strategies that target various sodium reduction barriers and strengthen beliefs regarding self-efficacy and autonomy support. Additionally, environmental interventions should be implemented to reduce sodium levels in processed

  16. Class barriers to psychotherapy and counselling.

    Science.gov (United States)

    Ollerton, I

    1995-01-01

    This paper focuses on the barriers to the uptake of counselling and psychotherapy from a social class perspective. It begins with a definition of class before discussing particular aspects that inhibit uptake. Barriers focused upon are those regarding travel, costs, child care, appointment times and location of actual therapists. Likewise barriers to the effective outcome, for example cognitive and verbal abilities of clients, are addressed and the way in which these barriers inhibit the referral rate from particular social groups. Finally the self-imposed barriers of certain social groups are explored regarding self exile from the counselling arena.

  17. Diffraction of sound by nearly rigid barriers

    Science.gov (United States)

    Hadden, W. J., Jr.; Pierce, A. D.

    1976-01-01

    The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control.

  18. Mathematical modeling of complex noise barriers

    Energy Technology Data Exchange (ETDEWEB)

    Hayek, S.I.

    1982-01-01

    Mathematical modeling of the noise reduction efficiency of highway noise barriers depends on the shape and absorptivity of the barrier, the influence of the impedance of the ground under the receiver, the atmospheric conditions as well as traffic details. The mathematical model for a barrier's noise reduction requires the knowledge of point-to-point acoustic diffraction models. In many instances, the shape of the barrier is simple; such as thin wall (edge), sharp wedge, and cylindrically topped berms. However, new designs of more efficient barriers have been investigated recently.

  19. Avoiding barriers in control of mowing robot

    Institute of Scientific and Technical Information of China (English)

    QIU Bai-jing; QIAN Guo-hong; XIANG Zhong-ping; LI Zuo-peng

    2006-01-01

    Due to complicated barriers,it is difficult to track the path of the mowing robot and to avoid barriers.In order to solve the problem,a method based on distance-measuring sensors and fuzzy control inputs was proposed.Its track was composed of beelines and was easy to tail.The fuzzy control inputs were based on the front barrier distance and the difference between the left and right barrier distance measured by ultrasonic sensors;the output was the direction angle.The infrared sensors around the robot improved its safety in avoiding barriers.The result of the method was feasible,agile,and stable.The distance between the robot and the barriers could be changed by altering the inputs and outputs of fuzzy control and the length of the beelines.The disposed sensors can fulfill the need of the robot in avoiding barriers.

  20. Dielectric barrier discharges in analytical chemistry.

    Science.gov (United States)

    Meyer, C; Müller, S; Gurevich, E L; Franzke, J

    2011-06-21

    The present review reflects the importance of dielectric barrier discharges in analytical chemistry. Special about this discharge is-and in contrast to usual discharges with direct current-that the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges; it can serve as dissociation and excitation device and as ionization mechanism, respectively. The article portrays the various application fields for dielectric barrier discharges in analytical chemistry, for example the use for elemental detection with optical spectrometry or as ionization source for mass spectrometry. Besides the introduction of different kinds of dielectric barrier discharges used for analytical chemistry from the literature, a clear and concise classification of dielectric barrier discharges into capacitively coupled discharges is provided followed by an overview about the characteristics of a dielectric barrier discharge concerning discharge properties and the ignition mechanism.

  1. Fish dispersal in fragmented landscapes: a modeling framework for quantifying the permeability of structural barriers.

    Science.gov (United States)

    Pépino, Marc; Rodríguez, Marco A; Magnan, Pierre

    2012-07-01

    Dispersal is a key determinant of the spatial distribution and abundance of populations, but human-made fragmentation can create barriers that hinder dispersal and reduce population viability. This study presents a modeling framework based on dispersal kernels (modified Laplace distributions) that describe stream fish dispersal in the presence of obstacles to passage. We used mark-recapture trials to quantify summer dispersal of brook trout (Salvelinus fontinalis) in four streams crossed by a highway. The analysis identified population heterogeneity in dispersal behavior, as revealed by the presence of a dominant sedentary component (48-72% of all individuals) characterized by short mean dispersal distance (dispersal distance (56-1086 m). We did not detect evidence of barrier effects on dispersal through highway crossings. Simulation of various plausible scenarios indicated that detectability of barrier effects was strongly dependent on features of sampling design, such as spatial configuration of the sampling area, barrier extent, and sample size. The proposed modeling framework extends conventional dispersal kernels by incorporating structural barriers. A major strength of the approach is that ecological process (dispersal model) and sampling design (observation model) are incorporated simultaneously into the analysis. This feature can facilitate the use of prior knowledge to improve sampling efficiency of mark-recapture trials in movement studies. Model-based estimation of barrier permeability and its associated uncertainty provides a rigorous approach for quantifying the effect of barriers on stream fish dispersal and assessing population dynamics of stream fish in fragmented landscapes.

  2. A welfare ranking of multilateral reductions in real and tariff trade barriers when firms are heterogenous

    DEFF Research Database (Denmark)

    Schröder, Philipp; Sørensen, Allan

    2014-01-01

    Trade liberalization comes about through reductions in various types of trade barriers. This paper introduces, apart from the customary real trade costs (i.e. iceberg and fixed export costs), two revenue generating trade barriers (i.e. an ad valorem tariff and a trade license) into a standard...... heterogeneous-firms-trade model with Pareto distributed productivities. We derive analytical welfare rankings of all four liberalization channels for an equal effect on two openness measures, for any trade cost level and while all four barriers are simultaneously present, i.e. for any initial equilibrium. We...

  3. Modeling, analysis, and validation of an active T-shaped noise barrier.

    Science.gov (United States)

    Fan, Rongping; Su, Zhongqing; Cheng, Li

    2013-09-01

    With ever-increasing land traffic, abatement of traffic noise using noise barriers remains significant, yet it is a challenging task due to spatial competition with other infrastructure. In this study, a deep insight into the diffraction characteristics of acoustic fields near noise barriers of various geometries and surface conditions was achieved using numerical simulations. A T-shaped passive noise barrier with acoustically soft upper surfaces was demonstrated to outperform other candidates in a middle- or high-frequency range. Based on attributes of the acoustic field diffracted by T-shaped barriers, an active control strategy was developed to revamp the T-shaped barrier, in which a filtered minimax algorithm was established to drive the secondary sound sources. This algorithm resulted in more uniformly distributed residual sound fields than a filtered-X least mean square algorithm. Performance of the actively controlled barrier was evaluated at different positions and spacings of secondary sound sources and error sensors, leading to a series of optimal criteria for the design of active noise barriers. A prototype was fabricated and validated experimentally, manifesting particular effectiveness in insulating low-frequency noise, supplementing well the capacity of a passive T-shaped barrier which is effective in the middle- or high-frequency range.

  4. Barriers and challenges in researches by Iranian students of medical universities.

    Science.gov (United States)

    Anbari, Zohreh; Mohammadbeigi, Abolfazl; Jadidi, Rahmatollah

    2015-01-01

    Health sciences research (HSR) is an essential part of improving health care which plays a critical role in the field of medicine and clinical practice. The aim of the current study was to assess barriers to the research by students of medical sciences as well as to find out effective strategies for management of student researches in Iranian universities. This study utilized a hybrid design with quantitative and qualitative analytical approaches conducted on 627 students in six schools of medical sciences in two universities in Central Province in Iran from April to December, 2012. Questionnaires were distributed among researcher and non-researcher students to find barriers to the research. These barriers were approved and validated by similar studies and strategies using the Delphi technique on 36 students. The most important barriers among researcher students were institutional barriers (3.3 ± 1.3), but in non-researcher students they were individual barriers (3.6 ± 1.7). The majority of barriers to involvement in the research among researcher students appeared to be time, lack of access to electronic resources and prolongation of the process of buying equipment. In addition, the greatest barriers among non-researcher students included the lack of time, scientific writing skills, and access to trained assistants. The results showed the issue of attitudes towards compulsory research as a component of critical scholarship in the curriculum of medical courses. Moreover, employment of the research experts can be helpful for research training in schools of medical sciences.

  5. Tunneling without barriers with gravity

    CERN Document Server

    Kanno, Sugumi; Soda, Jiro

    2012-01-01

    We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions describing tunneling without barriers in the presence of gravity. In the absence of gravity such instantons were found and discussed by Lee and Weinberg more than a quarter of a century ago. The bounce action is also analytically computed. We discuss possible implications of these new instantons to cosmology in the context of the string theory landscape.

  6. Potential corridors and barriers for plague spread in central Asia

    Science.gov (United States)

    2013-01-01

    Background Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap. Methods Three 20 by 20 km areas with known great gerbil burrow distributions were used to analyse the spatial distribution of the burrows. Object-based image analysis was used to map the landscape at several scales, and was linked to the burrow maps. A novel object-based method was developed – the mean neighbour absolute burrow density difference (MNABDD) – to identify the optimal scale and evaluate the efficacy of using landscape objects as opposed to square cells. Multiple regression using raster maps was used to identify the landscape-ecological variables that explain burrow density best. Functional corridors and barriers were mapped using burrow density thresholds. Cumulative resistance of the burrow distribution to potential disease spread was evaluated using cost distance analysis. A 46-year plague surveillance dataset was used to evaluate whether plague spread was radially symmetric. Results The burrow distribution was found to be non-random and negatively correlated with Greenness, especially in the floodplain areas. Corridors and

  7. Potential corridors and barriers for plague spread in Central Asia.

    Science.gov (United States)

    Wilschut, Liesbeth I; Addink, Elisabeth A; Heesterbeek, Hans; Heier, Lise; Laudisoit, Anne; Begon, Mike; Davis, Stephen; Dubyanskiy, Vladimir M; Burdelov, Leonid A; de Jong, Steven M

    2013-10-31

    Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap. Three 20 by 20 km areas with known great gerbil burrow distributions were used to analyse the spatial distribution of the burrows. Object-based image analysis was used to map the landscape at several scales, and was linked to the burrow maps. A novel object-based method was developed - the mean neighbour absolute burrow density difference (MNABDD) - to identify the optimal scale and evaluate the efficacy of using landscape objects as opposed to square cells. Multiple regression using raster maps was used to identify the landscape-ecological variables that explain burrow density best. Functional corridors and barriers were mapped using burrow density thresholds. Cumulative resistance of the burrow distribution to potential disease spread was evaluated using cost distance analysis. A 46-year plague surveillance dataset was used to evaluate whether plague spread was radially symmetric. The burrow distribution was found to be non-random and negatively correlated with Greenness, especially in the floodplain areas. Corridors and barriers showed a mostly NWSE

  8. Westinghouse thermal barrier coatings development

    Energy Technology Data Exchange (ETDEWEB)

    Goedjen, J.G.; Wagner, G. [Westinghouse Electric Corp., Orlando, FL (United States)

    1995-10-01

    Westinghouse, in conjunction with the Department of Energy and Oak Ridge National Laboratory, has embarked upon a program for the development of advanced thermal barrier coatings for industrial gas turbines. Development of thermal barrier coatings (TBC`s) for industrial gas turbines has relied heavily on the transfer of technology from the aerospace industry. Significant differences in the time/temperature/stress duty cycles exist between these two coating applications. Coating systems which perform well in aerospace applications may not been optimized to meet power generation performance requirements. This program will focus on development of TBC`s to meet the specific needs of power generation applications. The program is directed at developing a state-of-the-art coating system with a minimum coating life of 25,000 hours at service temperatures required to meet increasing operating efficiency goals. Westinghouse has assembled a team of university and industry leaders to accomplish this goal. Westinghouse will coordinate the efforts of all program participants. Chromalloy Turbine Technologies, Inc. and Sermatech International, Inc. will be responsible for bond coat and TBC deposition technology. Praxair Specialty Powders, Inc. will be responsible for the fabrication of all bond coat and ceramic powders for the program. Southwest Research Institute will head the life prediction modelling effort; they will also be involved in coordinating nondestructive evaluation (NDE) efforts. Process modelling will be provided by the University of Arizona.

  9. PWM Converter Power Density Barriers

    Science.gov (United States)

    Kolar, Johann W.; Drofenik, Uwe; Biela, Juergen; Heldwein, Marcelo; Ertl, Hans; Friedli, Thomas; Round, Simon

    Power density of power electronic converters has roughly doubled every 10 years since 1970. Behind this trajectory is the continuous advancement of power semiconductor devices, which has increased the converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts and passive components are major barriers for a continuation of this trend. To identify such technological barriers, this paper investigates the volume of the cooling system and passive components as a function of the switching frequency for power electronic converters and determines the switching frequency that minimizes the total volume. A power density limit of 28kW/dm3 at 300kHz is calculated for an isolated DC-DC converter, 44kW/dm3 at 820kHz for a three-phase unity power factor PWM rectifier, and 26kW/dm3 at 21kHz for a sparse matrix converter. For single-phase AC-DC conversion a general limit of 35kW/dm3 results from the DC link capacitor. These power density limits highlight the need to broaden the scope of power electronics research to include cooling systems, high frequency electromagnetics, interconnection and packaging technology, and multi-domain modelling and simulation to ensure further advancement along the power density trajectory.

  10. Overcoming Barriers in Unhealthy Settings

    Directory of Open Access Journals (Sweden)

    Michael K. Lemke

    2016-03-01

    Full Text Available We investigated the phenomenon of sustained health-supportive behaviors among long-haul commercial truck drivers, who belong to an occupational segment with extreme health disparities. With a focus on setting-level factors, this study sought to discover ways in which individuals exhibit resiliency while immersed in endemically obesogenic environments, as well as understand setting-level barriers to engaging in health-supportive behaviors. Using a transcendental phenomenological research design, 12 long-haul truck drivers who met screening criteria were selected using purposeful maximum sampling. Seven broad themes were identified: access to health resources, barriers to health behaviors, recommended alternative settings, constituents of health behavior, motivation for health behaviors, attitude toward health behaviors, and trucking culture. We suggest applying ecological theories of health behavior and settings approaches to improve driver health. We also propose the Integrative and Dynamic Healthy Commercial Driving (IDHCD paradigm, grounded in complexity science, as a new theoretical framework for improving driver health outcomes.

  11. Barriers to medical error reporting

    Directory of Open Access Journals (Sweden)

    Jalal Poorolajal

    2015-01-01

    Full Text Available Background: This study was conducted to explore the prevalence of medical error underreporting and associated barriers. Methods: This cross-sectional study was performed from September to December 2012. Five hospitals, affiliated with Hamadan University of Medical Sciences, in Hamedan,Iran were investigated. A self-administered questionnaire was used for data collection. Participants consisted of physicians, nurses, midwives, residents, interns, and staffs of radiology and laboratory departments. Results: Overall, 50.26% of subjects had committed but not reported medical errors. The main reasons mentioned for underreporting were lack of effective medical error reporting system (60.0%, lack of proper reporting form (51.8%, lack of peer supporting a person who has committed an error (56.0%, and lack of personal attention to the importance of medical errors (62.9%. The rate of committing medical errors was higher in men (71.4%, age of 50-40 years (67.6%, less-experienced personnel (58.7%, educational level of MSc (87.5%, and staff of radiology department (88.9%. Conclusions: This study outlined the main barriers to reporting medical errors and associated factors that may be helpful for healthcare organizations in improving medical error reporting as an essential component for patient safety enhancement.

  12. Specific features of waveguide recombination in laser structures with asymmetric barrier layers

    DEFF Research Database (Denmark)

    Polubavkina, Yu; Zubov, F. I.; Moiseev, E.

    2017-01-01

    The spatial distribution of the intensity of the emission caused by recombination appearing at a high injection level (up to 30 kA/cm2) in the waveguide layer of a GaAs/AlGaAs laser structure with GaInP and AlGaInAs asymmetric barrier layers is studied by means of near-field scanning optical...... microscopy. It is found that the waveguide luminescence in such a laser, which is on the whole less intense as compared to that observed in a similar laser without asymmetric barriers, is non-uniformly distributed in the waveguide, so that the distribution maximum is shifted closer to the p-type cladding...... layer. This can be attributed to the ability of the GaInP barrier adjoining the quantum well on the side of the n-type cladding layer to suppress the hole transport....

  13. Experimental study of a wake behind a barrier

    Science.gov (United States)

    Tomáš, Dufek; Katarína, Ratkovská

    2017-09-01

    This article describes in detail an experiment which was carried out on a wind tunnel in the Laboratory of the Department of Power Machines, Faculty of Mechanical Engineering, at the University of West Bohemia (UWB), using Particle Image Velocimetry and Stereo Particle Image Velocimetry. PIV is a non-invasive method that allows you to simultaneously measure the flow velocity across the entire field under investigation. In the experiment, the field was located behind the exit of the wind tunnel. The experiment dealt with the measurement of the wake behind a barrier. Measurement with Stereo PIV was carried out in several vertical parallel planes perpendicular to the axis of the tunnel. Conventional PIV method was then used for a horizontal plane passing through the axis of the tunnel at half the height of the barrier. The velocities in the measured plane are expressed by a vector map. In areas not affected by the wake, the speed in the w direction is about 16 m / s. The wake is formed behind the barrier. A shear layer is formed at the boundary between the flowing air and the braked air. A backflow occurs in the area just behind the barrier. The highest speed in the area is achieved in places just behind the exit of the tunnel, where the current is not affected by the barrier. In the direction from the axis and the obstacle, the speed gradually rises from the negative values of the return flow through the zero speed. In addition to the velocity fields, the output from the experimental measurement was also the distribution of the sum of variances, standard deviation and correlation coefficient in the measured planes.

  14. Barriers towards participation in adult education and training

    DEFF Research Database (Denmark)

    Larson, Anne; Milana, Marcella

    Based on exploratory factor analysis of data from a special Eurobarometer-survey dedicated to lifelong learning, different categories of reasons for not taking part in adult education and training is developed. 18.000 people living in the 15 old EU member countries in the survey were among other...... topics were asked what would be the most likely obstacles if they wanted to take part in education and training. The distribution of the different categories of barriers among different socio-economic groups is afterwards tested by use of logistic regression using Odds Ratios. As a result...... of the exploratory factor analysis, five categories of barriers towards participation in adult education and training is developed: Lack of time and energy; negative towards re-entering education; accessibility of learning activities; lack of support; and lack of confidence in own abilities. The factors have been...

  15. A study to determine important barriers in using managerial accounting

    Directory of Open Access Journals (Sweden)

    Rahmatollah Mohammadipour

    2012-09-01

    Full Text Available Managerial accounting plays an important role for making prompt and efficient decisions to reduce troubles in the market. However, there are many circumstances where management team cannot make appropriate, fast and reliable managerial decisions. In this paper, we present a survey in cement industry and look to find out important factors as major barriers of managerial accounting implementation. The proposed model of this paper designs and distributes questionnaire among management teams who work for cement industry in Iran. The results of the survey indicate that lack of familiarity of managers with managerial accounting techniques, existence of unprofessional people in financial and accounting affairs and lack of having globally acceptable standards are major barriers in this industry for implementation of managerial accounting skills. However, our survey does not find any relationship between market turbulence and efficiency and implementation of managerial accounting skills.

  16. A preliminary experimental study on virtual sound barrier system

    Science.gov (United States)

    Zou, Haishan; Qiu, Xiaojun; Lu, Jing; Niu, Feng

    2007-10-01

    Virtual sound barrier (VSB) is an array of loudspeakers and microphones forming an acoustic barrier, which creates a quiet zone without blocking air and light. A 16-channel cylindrical VSB system has been developed and its feasibility is verified by both numerical simulations and experiments. Experimental results in a normal room show that it can create a quiet zone larger than the size of a human head in the low-middle frequency, with a total sound pressure level reduction of more than 10 dB in the quiet zone. The control performance of the system with respect to the frequency, the distribution of the error sensors and the control sources are discussed.

  17. [Facilitators and barriers for the consumption of a micronutrient supplement].

    Science.gov (United States)

    Escalante-Izeta, Ericka; Bonvecchio, Anabelle; Théodore, Florence; Nava, Fernanda; Villanueva, María Angeles; Rivera-Dommarco, Juan Angel

    2008-01-01

    To define and explore the sociocultural factors that could enhance (facilitators) or interfere with (barriers) the adequate consumption of a nutritional supplement (NS) by children from 6 to 59 months of age, provided as part of the national program Oportunidades. Qualitative study in rural communities of Chiapas and Veracruz. Forty-four semi-structured interviews and 25 focus groups were conducted with mothers and other key informants. The framework analysis approach was used. Facilitators. The NS is free, is highly accessible, is positively accepted and mothers believe the physicians recommendations. Barriers. Lack of adequate storage and distribution, poverty conditions, intrahousehold dilution (within the family members), beliefs regarding child feeding and the purpose of the NS. Results shows the incongruence between the Programs recommendations and the preferences and practices of the target population and provides important elements to be considered in the promotion of the NS .

  18. Technical Basis for Evaluating Surface Barriers to Protect Groundwater from Deep Vadose Zone Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Fayer, Michael J.; Ward, Anderson L.; Freedman, Vicky L.

    2010-02-03

    This document presents a strategy for evaluating the effectiveness of surface barriers for site-specific deep vadose zone remediation. The strategy provides a technically defensible approach to determine the depth to which a surface barrier can effectively isolate contaminants in the vadose at a specific site as a function of subsurface properties, contaminant distribution, barrier design, and infiltration control performance. The strategy also provides an assessment of additional data and information needs with respect to surface barrier performance for deep vadose zone applications. The strategy addresses the linkage between surface barriers and deep vadose zone in situ remediation activities, monitoring issues, and emerging science, technology, and regulatory objectives. In short, the report documents the existing knowledge base, identifies knowledge needs (based on data gaps), and suggests tasks whose outcomes will address those knowledge needs. More important, the report serves as a starting point to engage the regulator and stakeholder community on the viability of deploying surface barriers for deep vadose zone contamination. As that engagement unfolds, a systematic methodology can be formalized and instituted. The strategy is focused on deep vadose zone contamination and the methods needed to determine the impact to groundwater from those deep vadose zone contaminants. Processes that affect surface barrier performance, recharge in the areas surrounding the surface barrier, and the near-surface vadose zone beneath the barrier are acknowledged but are not addressed by this strategy. In addition, the collection of site-specific data on contaminant distribution and geologic structure and properties are programmatic responsibilities and are not provided by this strategy.

  19. Barrier experiment: Shock initiation under complex loading

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-01-12

    The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

  20. Assessing Controls on the Geometry and Dimensions of Modern Barrier Islands

    Science.gov (United States)

    Mulhern, J.; Johnson, C. L.; Martin, J. M.

    2015-12-01

    Barrier islands are highly ephemeral features, shaped by wave, tide, and storm energy. The processes that govern the size, shape, and motion of barrier islands are not well constrained, yet central to coastal dynamics. While the global distribution of barrier islands has been mapped and assessed, there is little consensus on the forces controlling barrier island formation, motion, or preservation. This study presents a new semi-global database of modern barrier islands to better understand their morphology and spatial distribution. We have mapped, in Google Earth, the subaerial extent of >350 barrier islands and spits, measuring spatial characteristic such as exposed area, perimeter, length, and width. These objects are cross-referenced with parameters that potentially control morphology, including tidal range, wave height, climate, distance from the continental shelf, proximity to fluvial output, and tectonic setting. This approach provides a more optimal framework to assess controls on coastal features, including barrier island morphology, and to investigate potential geometric scaling relationships. Preliminary analysis shows trends in the spatial characteristics of barrier islands. There is a strong linear relationship between the perimeter and length (y= -0.59 + 0.42x, R2=0.95). Linear trends also relate length to area when the data are separated by tidal range to wave height ratio. Assessment of barrier island shape supports the hypothesis of Hayes (1979) that barrier islands in wave-dominated settings are long and linear while those in mixed energy setting are more rounded. The barrier islands of the Texas Gulf of Mexico are larger than the global average for the database, with distinctly longer length values (41.16 km vs. 15.77 km respectively) and larger areas (103.81 km2 vs. 42.14 km2 respectively). Initial assessment shows that tidal range and wave height are primary controls barrier island dimensions. Future work will consider climate, latitude, fluvial

  1. Identification of Key Barriers in Workforce Development

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-03-31

    This report documents the identification of key barriers in the development of an adequate national security workforce as part of the National Security Preparedness Project, being performed under a Department of Energy/National Nuclear Security Administration grant. Many barriers exist that prevent the development of an adequate number of propertly trained national security personnel. Some barriers can be eliminated in a short-term manner, whereas others will involve a long-term strategy that takes into account public policy.

  2. The biological significance of brain barrier mechanisms

    DEFF Research Database (Denmark)

    Saunders, Norman R; Habgood, Mark D; Møllgård, Kjeld

    2016-01-01

    properties. In the blood-brain barrier proper, this is combined with a paucity of vesicular transport that is a characteristic of other vascular beds. Without such a diffusional restrain, the cellular transport mechanisms in the barrier interfaces would be ineffective. Superimposed on these physical....... In addition, such studies, if applied to brain pathologies such as stroke, trauma, or multiple sclerosis, will aid in defining the contribution of brain barrier pathology to these conditions, either causative or secondary....

  3. Barriers for realisation of energy savings in buildings; Barrierer for realisering af energibesparelser i bygninger

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, O.M.

    2004-07-01

    Many years' efforts within the energy labelling area have shown large saving potentials in heating and use of electricity in buildings. At the same time it has been proved that these saving potentials, even when economically advantageous, only are cashed to a limited extent. The reason to this is ascribed to barriers that meet the individual building owner who wants to start saving energy. Most barriers are known and a lot of these have been sought overcome for some time. The questions are how many barriers still exist, have new barriers arisen and the character of these barriers. On this background the objective of this survey has been to concretize and study the barriers, which are blocking reasonable energy savings. Focus has especially been on barriers for realisation of heating savings, but through a general evaluation of energy savings of barriers other forms of energy saving methods have been taken into consideration. Special interest has been directed towards houses, typically one family houses, which are affected by the Energy Labelling Scheme. The concept barriers include all kinds of barriers, also barriers that not are acknowledged as barriers by the individual house owner, or that on closer inspection turn out to be something else than actual barriers. This note suggests an alternative inertia model, in order to create an idea of the inertness characteristic of the many house owners who understand the message but fail to act on it. (BA)

  4. Barriers Approach to Innovation in Academic Libraries

    Directory of Open Access Journals (Sweden)

    Fu-Hsuan Chuang

    2016-11-01

    Full Text Available Innovation in academic libraries is not a brand new issue. Academic libraries can benefit from successful innovation, since innovation is a key contributor to gaining and sustaining competitive advantage for survival. Building on two case studies, 28 participants from leadership teams to practitioners are involved, the qualitative findings identified the specific two types of barriers that academic libraries face by applying a barriers approach to innovation, that’s, environmental and organizational barriers. Especially, seven dimensions of two types of barriers to innovation are found.

  5. Altered permeability barrier structure in cholesteatoma matrix

    DEFF Research Database (Denmark)

    Svane-Knudsen, Viggo; Halkier-Sørensen, Lars; Rasmussen, Gurli

    2002-01-01

    The stratum corneum of the cholesteatoma epithelium comprises the greater part of the cholesteatoma matrix. The permeability barrier that militates against diffusion and penetration of infectious and toxic agents into and through the epithelium is situated here. The multiple long sheets of lamellar...... lipid structures filling the intercellular spaces mainly control the barrier function. The barrier in cholesteatoma epithelium is several times thicker than in unaffected skin but presents distinctive features of a defective barrier as seen in other scaling skin diseases. The intercellular spaces appear...

  6. Pratt & Whitney thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bornstein, N. [United Technologies Research Center, East Hartford, CT (United States); Marcin, J. [Pratt & Whitney Aircraft Co., East Hartford, CT (United States)

    1995-10-01

    The objective of the Advanced Turbine Systems (ATS) Program is to develop ultra-high efficient, environmentally superior, and cost competitive gas turbine systems. The operating profiles of these industrial gas turbines are long, less cyclic with fewer transients-compared with those for aircraft gas turbine engines. Therefore, creep rather than thermal fatigue, becomes primary life-limiting for hot section components. Thermal barrier coatings (TBCs) will be used to achieve the objectives of the program. TBCs allow surface temperatures to increase without compromising the structural properties of the alloy. TBCs typically consist of a ceramic insulating layer, deposited onto the substrate with an intervening metallic layer, which imparts oxidation protection to the substrate and provides a surface to which the ceramic layer can adhere.

  7. Distribution Structures

    NARCIS (Netherlands)

    Friedrich, H.; Tavasszy, L.A.; Davydenko, I.

    2013-01-01

    Distribution structures are important elements of the freight transportation system. Goods are routed via warehouses on their way from production to consumption. This chapter discusses drivers behind these structures, logistics decisions connected to distribution structures on the micro level, and

  8. Distributed Knight

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius; Damm, Christian Heide

    2005-01-01

    An extension of Knight (2005) that support distributed synchronous collaboration implemented using type-based publish/subscribe......An extension of Knight (2005) that support distributed synchronous collaboration implemented using type-based publish/subscribe...

  9. Impact of language barrier on acute care medical professionals is dependent upon role.

    Science.gov (United States)

    Bernard, Andrew; Whitaker, Misty; Ray, Myrna; Rockich, Anna; Barton-Baxter, Marietta; Barnes, Stephen L; Boulanger, Bernard; Tsuei, Betty; Kearney, Paul

    2006-01-01

    Communication with patients is essential to providing quality medical care. The study was conducted to evaluate the effects of language barriers on health care professionals. It is hypothesized that these language barriers are commonly perceived by health care professionals and they are a source of workplace stress in acute care environments. We designed and distributed a survey tool of staff experiences and attitudes regarding the English-Spanish language barrier among patients in an acute care surgical environment of a tertiary medical center. Responses were anonymous, stratified by professional role and comparisons made using paired t tests. Sixty-one nurses and 36 physicians responded to the survey. Overall, 95% of nurses reported that the language barrier was an impediment to quality care, whereas 88% of physicians responded similarly (P = .0004). More nurses than physicians report experiencing stress (97% vs. 78%) and the degree of stress appears to be greater for nurses (P language barriers as an impediment to quality care delivery and as a source of workplace stress. Nurse and physician perceptions differ; therefore, strategies to address these language barriers should be specific to those professional roles. These barriers create a void in health care quality and safety that has effects on health care professionals.

  10. Improved epidermal barrier formation in human skin models by chitosan modulated dermal matrices

    Science.gov (United States)

    Mieremet, Arnout; Rietveld, Marion; Absalah, Samira; van Smeden, Jeroen

    2017-01-01

    Full thickness human skin models (FTMs) contain an epidermal and a dermal equivalent. The latter is composed of a collagen dermal matrix which harbours fibroblasts. Current epidermal barrier properties of FTMs do not fully resemble that of native human skin (NHS), which makes these human skin models less suitable for barrier related studies. To further enhance the resemblance of NHS for epidermal morphogenesis and barrier formation, we modulated the collagen dermal matrix with the biocompatible polymer chitosan. Herein, we report that these collagen-chitosan FTMs (CC-FTMs) possess a well-organized epidermis and maintain both the early and late differentiation programs as in FTMs. Distinctively, the epidermal cell activation is reduced in CC-FTMs to levels observed in NHS. Dermal-epidermal interactions are functional in both FTM types, based on the formation of the basement membrane. Evaluation of the barrier structure by the organization of the extracellular lipid matrix of the stratum corneum revealed an elongated repeat distance of the long periodicity phase. The ceramide composition exhibited a higher resemblance of the NHS, based on the carbon chain-length distribution and subclass profile. The inside-out barrier functionality indicated by the transepidermal water loss is significantly improved in the CC-FTMs. The expression of epidermal barrier lipid processing enzymes is marginally affected, although more restricted to a single granular layer. The novel CC-FTM resembles the NHS more closely, which makes them a promising tool for epidermal barrier related studies. PMID:28333992

  11. Energy management action plan: Developing a strategy for overcoming institutional barriers to municipal energy conservation

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    Energy offices working to improve efficiency of local government facilities face not only technical tasks, but institutional barriers, such as budget structures that do not reward efficiency, a low awareness of energy issues, and purchasing procedures based only on minimizing initial cost. The bureau, in working to remove such barriers in San Francisco, has identified 37 institutional barriers in areas such as operations & maintenance, purchasing, and facility design; these barriers were then reorganized into three groupings-- policy & attitudes, budget & incentives, and awareness & information-- and mapped. This map shows that the barriers mutually reinforce each other, and that a holistic approach is required for permanent change. The city`s recreation & parks department was used as a model department, and information about facility energy use was compiled into a departmental energy review. Staff interviews showed how barriers affect conservation. The bureau then generated ideas for projects to remove specific barriers and rated them according to potential impact and the resources required to implement them. Four of the six projects selected focused on maintenance staff: a cost- sharing lighting retrofit program, a boiler efficiency program, a departmental energy tracking system, and a budgetary incentive program for conservation. The other two projects are city-wide: promotion of a new term contract supplying energy-efficient light materials, and publication/distribution of ENERGY NEWS newsletter. A general methodology, the EMAP Strategy Guide, has been created to assist other energy offices in developing EMAPs.

  12. Communication: New insight into the barrier governing CO2 formation from OH + CO.

    Science.gov (United States)

    Johnson, Christopher J; Poad, Berwyck L J; Shen, Ben B; Continetti, Robert E

    2011-05-07

    Despite its relative simplicity, the role of tunneling in the reaction OH + CO → H + CO(2) has eluded the quantitative predictive powers of theoretical reaction dynamics. In this study a one-dimensional effective barrier to the formation of H + CO(2) from the HOCO intermediate is directly extracted from dissociative photodetachment experiments on HOCO and DOCO. Comparison of this barrier to a computed minimum-energy barrier shows that tunneling deviates significantly from the calculated minimum-energy pathway, predicting product internal energy distributions that match those found in the experiment and tunneling lifetimes short enough to contribute significantly to the overall reaction. This barrier can be of direct use in kinetic and statistical models and aid in the further refinement of the potential energy surface and reaction dynamics calculations for this system.

  13. Electron Holography of Barrier Structures in Co/ZrAlOx/Co Magnetic Tunnel Junctions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; ZHU Tao; SHEN Feng; SHENG Wen-Ting; WANG Wei-Gang; XIAO John Q; ZHANG Ze

    2005-01-01

    @@ We investigate the potential profiles and elemental distribution of barriers in Co/ZrAlOx/Co magnetic tunnel junctions (MTJs) using electron holography (EH) and scanning transmission electron microscopy. The MTJ barriers are introduced by oxidizing a bilayer consisting with a uniform 0.45-nm Al layer and a wedge-shaped Zr layer (0-2 nm). From the scanning transmission electron microscopy, AlOx and ZrOx layers are mixed together,indicating that compact AlOx layer cannot be formed in such a bilayer structure of barriers. The EH results reveal that there are no sharp interfaces between the barrier and magnetic electrodes, which may be responsible for a smaller tunnelling magnetoresistance compared with the MTJs of Co/AlOx/Co.

  14. Crash barrier research in the Netherlands.

    NARCIS (Netherlands)

    Flury, F.C. & Paar, H.G.

    1973-01-01

    Research by the SWOV has led to the development of a series of crash barriers of basically the same design but with varying degrees of resistance to lateral deflection. Requirements to which in general a crash barrier should fulfill are presented.

  15. Barriers to adherence in cystic fibrosis

    DEFF Research Database (Denmark)

    Bregnballe, Vibeke; Schiøtz, Peter Oluf

    2012-01-01

    Danish patients with cystic fibrosis aged 14 to 25 years and their parents. Conclusions: The present study showed that the majority of adolescents with CF and their parents experienced barriers to treatment adherence. Patients and parents agreed that the three most common barriers encountered lack...

  16. Overcoming Blocks and Barriers to Creativity.

    Science.gov (United States)

    Raudsepp, Eugene

    1982-01-01

    Organizational barriers to creativity are examined. It is noted that resistance to change is a major impediment to creative problem solving in most organizations. Understanding the barriers to change that exist is viewed to help people exercise and develop their creativity more fully and effectively. (MP)

  17. Storm impacts on small barrier islands

    DEFF Research Database (Denmark)

    Kroon, Aart; Fruergaard, Mikkel

    The shorelines of the Baltic Sea and the inner coastal waters in Denmark consist of many barrier islands. These sandy barrier islands were mainly formed in the Holocene and are still very dynamic. The present day changes in the morphology are dominantly governed by storm waves and associated high...

  18. Fracture mechanism of a thermal barrier coating

    Science.gov (United States)

    Samoilenko, V. M.; Ravilov, R. G.; Drevnyak, V. V.; Petrova, M. A.

    2016-06-01

    The fracture mechanism of the thermal barrier coating of gas turbine blades is studied. The causes of the fracture of the ceramic layer are discussed and the possible ways to increase the fatigue life of the thermal barrier coating are considered.

  19. Nurses' barriers to learning: an integrative review.

    Science.gov (United States)

    Santos, Marion C

    2012-07-01

    This integrative review of the literature describes nurses' barriers to learning. Five major themes emerged: time constraints, financial constraints, workplace culture, access/relevance, and competency in accessing electronic evidence-based practice literature. The nurse educator must address these barriers for the staff to achieve learning and competency.

  20. Antimicrobial Peptides, Infections and the Skin Barrier

    DEFF Research Database (Denmark)

    Clausen, Maja-Lisa; Agner, Tove

    2016-01-01

    The skin serves as a strong barrier protecting us from invading pathogens and harmful organisms. An important part of this barrier comes from antimicrobial peptides (AMPs), which are small peptides expressed abundantly in the skin. AMPs are produced in the deeper layers of the epidermis...

  1. Near barrier scattering of 8He on 208Pb

    Directory of Open Access Journals (Sweden)

    Marquínez-Durán G.

    2014-03-01

    Full Text Available The exotic nucleus 8He is investigated by means of the measurement of the angular distributions of the elastic channel and the 6He and 4He fragment yields produced in the collision with a 208Pb target at two energies around the Coulomb barrier, 16 and 22 MeV. The experiment was performed at the GANIL-SPIRAL facility, with the aim of extracting information about the structure of 8He and the relevant reaction mechanisms. In this contribution, details of the experimental setup and preliminary data on elastic cross sections are reported.

  2. Mucus as a Barrier to Drug Delivery

    DEFF Research Database (Denmark)

    Bøgh, Marie; Nielsen, Hanne Mørck

    2015-01-01

    Viscoelastic mucus lines all mucosal surfaces of the body and forms a potential barrier to mucosal drug delivery. Mucus is mainly composed of water and mucins; high-molecular weight glycoproteins forming an entangled network. Consequently, mucus forms a steric barrier and due to its negative charge...... and hydrophobic domains, the overall hydrophilic mucus also presents an interactive barrier limiting the free diffusion of components within and through the mucus. Furthermore, mucus is a dynamic barrier due to its continuous secretion and shedding from the mucosal surfaces. Mucus is thus a highly complex gel......, studies of peptide and protein drug diffusion in and through mucus and studies of mucus-penetrating nanoparticles are included to illustrate the mucus as a potentially important barrier to obtain sufficient bioavailability of orally administered drugs, and thus an important parameter to address...

  3. Advancements in subsurface barrier wall technology

    Energy Technology Data Exchange (ETDEWEB)

    Mutch, R.D. Jr.; Ash, R.E. IV; Caputi, J.R. [Eckenfelder Inc., Mahwah, NJ (United States)

    1995-12-31

    Subsurface barrier walls have been an important component of site remediation efforts for nearly thirty years. However, until the last decade, limited design options were available for barrier wall construction. Most barrier walls were constructed using traditional technologies such as soil-bentonite slurry trench and, in some instances, conventional compacted clay. While other technologies certainly existed, such as vibrating beam and sheet pile walls, they represented a minor share of the remediation market. Today the remediation engineer considering a subsurface barrier wall-based remediation is confronted with a baffling array, of new technologies and permutations of these technologies. Moreover, new technologies are entering the marketplace seemingly on a monthly basis. A partial listing of available barrier wall technologies is presented.

  4. Barriers to physical activity among working mothers.

    Science.gov (United States)

    Dombrowski, Jill J

    2011-04-01

    Working mothers experience several barriers to physical activity. If these barriers can be identified by occupational health nurses and they can partner with working mothers to reduce these perceived barriers, the health of these workers can be improved and chronic disease risk prevented. The purpose of this study was to measure the effect of self-regulatory efficacy on physical activity among working mothers and to describe specific barriers to physical activity. The Barriers Specific Self-Efficacy Scale (BARSE) and the Kaiser Physical Activity Survey (KPAS) were used to measure the variables. Self-regulatory efficacy was found to be a strong predictor of physical activity in a diverse sample of working mothers who did not meet current recommendations for physical activity. Occupational health nurses can use these findings to design programs for groups and for counseling individuals.

  5. Distributed computing

    CERN Document Server

    Van Renesse, R

    1991-01-01

    This series will start with an introduction to distributed computing systems. Distributed computing paradigms will be presented followed by a discussion on how several important contemporary distributed operating systems use these paradigms. Topics will include processing paradigms, storage paradigms, scalability and robustness. Throughout the course everything will be illustrated by modern distributed systems notably the Amoeba distributed operating system of the Free University in Amsterdam and the Plan 9 operating system of AT&T Bell Laboratories. Plan 9 is partly designed and implemented by Ken Thompson, the main person behind the successful UNIX operating system.

  6. Li-ion conduction in the LiBH4:LiI system from Density Functional Theory calculations and Quasi-Elastic Neutron Scattering

    DEFF Research Database (Denmark)

    Myrdal, Jon Steinar Gardarsson; Blanchard, Didier; Sveinbjörnsson, Dadi Þorsteinn

    2013-01-01

    defect sites, giving rise to high defect mobility. QENS results at 380 K show long-range diffusion of Li+, with jump lengths of one unit cell and jump rates in agreement with those obtained from DFT, and the application of the bias potential increases the diffusion constant by a factor of 2. At 300 K......The hexagonal high-temperature polymorph of LiBH4 is stabilized by solid solution with LiI to exhibit superionic Li+ ionic conductivity at room temperature. Herein, the mechanisms for the Li+ diffusion are investigated for the first time by density functional theory (DFT) calculations coupled......, the QENS data reveal jump events of shorter length (2 Å), which could correspond to a jump process of Li+ interstitials to an intermediate lattice site, in agreement with DFT calculations....

  7. Identifying real and perceived barriers to therapeutic education programs for individuals with inflammatory arthritis.

    Science.gov (United States)

    Bain, Lorna; Sangrar, Ruheena; Bornstein, Carolyn; Lukmanji, Sara; Hapuhennedige, Sandani; Thorne, Carter; Beattie, Karen A

    2016-09-01

    Therapeutic Education Programs (TEPs) grounded in self-management principles have been shown to improve quality of life of patients with chronic conditions and reduce patient-related healthcare costs. Though these programs are becoming more readily available, patients often experience barriers in participating. This study sought to identify barriers faced by inflammatory arthritis (IA) patients in attending a TEP and understand how patients overcame perceived barriers. A mixed-method study design was used. Questionnaires were distributed to individuals with IA who were invited to attend a TEP between 2010 and 2013. Respondents were those that chose not to attend (group A), individuals who attended ≤4 of 10 sessions (group B), individuals who attended ≥5 of 10 sessions prior to May 2013 (group C), and individuals who attended ≥5 of 10 sessions from June 2013 to November 2013 (group D). Individuals in group D were also invited to participate in focus groups to discuss how they had overcome perceived barriers. Real barriers identified by individuals in groups A and B included time, distance, and cost associated with attendance. Individuals who overcame perceived barriers (groups C and D) discussed strategies they used to do so. Aspects of the overall program experience and access to clinic and program also contributed to patients being able to overcome barriers. Time, distance, and cost are external barriers that prevented individuals from utilizing self-management education opportunities. These barriers were overcome if and when individuals had resources available to them. Readiness for behavior change also influenced commitment to participate in the program.

  8. Advanced thermal barrier coating systems

    Science.gov (United States)

    Dorfman, M. R.; Reardon, J. D.

    1985-01-01

    Current state-of-the-art thermal barrier coating (TBC) systems consist of partially stabilized zirconia coatings plasma sprayed over a MCrAlY bond coat. Although these systems have excellent thermal shock properties, they have shown themselves to be deficient for a number of diesel and aircraft applications. Two ternary ceramic plasma coatings are discussed with respect to their possible use in TBC systems. Zirconia-ceria-yttria (ZCY) coatings were developed with low thermal conductivities, good thermal shock resistance and improved resistance to vanadium containing environments, when compared to the baseline yttria stabilized zirconia (YSZ) coatings. In addition, dense zirconia-titania-yttria (ZTY) coatings were developed with particle erosion resistance exceeding conventional stabilized zirconia coatings. Both coatings were evaluated in conjunction with a NiCr-Al-Co-Y2O3 bond coat. Also, multilayer or hybrid coatings consisting of the bond coat with subsequent coatings of zirconia-ceria-yttria and zirconia-titania-yttria were evaluated. These coatings combine the enhanced performance characteristics of ZCY with the improved erosion resistance of ZTY coatings. Improvement in the erosion resistance of the TBC system should result in a more consistent delta T gradient during service. Economically, this may also translate into increased component life simply because the coating lasts longer.

  9. Overcoming Biological Barriers with Ultrasound

    Science.gov (United States)

    Thakkar, Dhaval; Gupta, Roohi; Mohan, Praveena; Monson, Kenneth; Rapoport, Natalya

    2011-01-01

    Effect of ultrasound on the permeability of blood vessels and cell membranes to macromolecules and nanodroplets was investigated using mouse carotid arteries and tumor cells. Model macromolecular drug, FITC-dextran with molecular weight of 70,000 Da was used in experiments with carotid arteries. The effect of unfocused 1-MHz ultrasound and and perfluoro-15-crown-5-ether nanodroplets stabilized with the poly(ethylene oxide)-co-poly(D,L-lactide) block copolymer shells was studied. In cell culture experiments, ovarian carcinoma cells and Doxorubicin (DOX) loaded poly(ethylene oxide)-co-polycaprolactone nanodroplets were used. The data showed that the application of ultrasound resulted in permeabilization of all biological barriers tested. Under the action of ultrasound, not only FITC-dextran but also nanodroplets effectively penetrated through the arterial wall; the effect of continuous wave ultrasound was stronger than that of pulsed ultrasound. In cell culture experiments, ultrasound triggered DOX penetration into cell nuclei, presumably due to releasing the drug from the carrier. Detailed mechanisms of the observed effects require further study. PMID:24839333

  10. Transport in the barrier billiard

    Science.gov (United States)

    Saberi Fathi, S. M.; Ettoumi, W.; Courbage, M.

    2016-06-01

    We investigate transport properties of an ensemble of particles moving inside an infinite periodic horizontal planar barrier billiard. A particle moves among bars and elastically reflects on them. The motion is a uniform translation along the bars' axis. When the tangent of the incidence angle, α , is fixed and rational, the second moment of the displacement along the orthogonal axis at time n , , is either bounded or asymptotic to K n2 , when n →∞ . For irrational α , the collision map is ergodic and has a family of weakly mixing observables, the transport is not ballistic, and autocorrelation functions decay only in time average, but may not decay for a family of irrational α 's. An exhaustive numerical computation shows that the transport may be superdiffusive or subdiffusive with various rates or bounded strongly depending on the values of α . The variety of transport behaviors sounds reminiscent of well-known behavior of conservative systems. Considering then an ensemble of particles with nonfixed α , the system is nonergodic and certainly not mixing and has anomalous diffusion with self-similar space-time properties. However, we verified that such a system decomposes into ergodic subdynamics breaking self-similarity.

  11. Engineered barrier environment, Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Wilder, D.G. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    The suitability of Yucca Mountain (YM) as a potential nuclear waste repository site will ultimately depend on how well it provides for isolation of the waste. Analysis of isolation capabilities of YM must consider interactions between natural and engineered systems. In addition, environmental conditions are important to EBS design, materials testing, selection, design criteria, and waste-form characterization. Studies of environmental interactions with the EBS, have emphasized processes and changed (not ambient) conditions resulting from interaction with waste, since these are the pertinent conditions for the EBS. The results of these studies indicate that the radioactive heat-of-decay from spent nuclear fuel will play a dominant role in the performance of a potential repository at Yucca Mountain. In addition, coupled hydrothermal-geochemical phenomena may significantly affect the performance of natural barriers surrounding the repository. Depending on the thermal-loading management strategy, as well as site conditions, repository heat may either substantially increase the likelihood of water contacting waste packages, with an associated potential increased magnitude of release and transport of radionuclides, or preclude, or at least minimize, these effects for extended periods of time, perhaps as much as hundreds of thousand years.

  12. The immunological barriers to xenotransplantation.

    Science.gov (United States)

    Vadori, M; Cozzi, E

    2015-10-01

    The availability of cells, tissues and organs from a non-human species such as the pig could, at least in theory, meet the demand of organs necessary for clinical transplantation. At this stage, the important goal of getting over the first year of survival has been reported for both cellular and solid organ xenotransplantation in relevant preclinical primate models. In addition, xenotransplantation is already in the clinic as shown by the broad use of animal-derived medical devices, such as bioprosthetic heart valves and biological materials used for surgical tissue repair. At this stage, however, prior to starting a wide-scale clinical application of xenotransplantation of viable cells and organs, the important obstacle represented by the humoral immune response will need to be overcome. Likewise, the barriers posed by the activation of the innate immune system and coagulative pathway will have to be controlled. As far as xenogeneic nonviable xenografts, increasing evidence suggests that considerable immune reactions, mediated by both innate and adaptive immunity, take place and influence the long-term outcome of xenogeneic materials in patients, possibly precluding the use of bioprosthetic heart valves in young individuals. In this context, the present article provides an overview of current knowledge on the immune processes following xenotransplantation and on the possible therapeutic interventions to overcome the immunological drawbacks involved in xenotransplantation.

  13. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  14. A Bayesian Network to Predict Barrier Island Geomorphologic Characteristics

    Science.gov (United States)

    Gutierrez, B.; Plant, N. G.; Thieler, E. R.; Turecek, A.; Stippa, S.

    2014-12-01

    Understanding how barrier islands along the Atlantic and Gulf coasts of the United States respond to storms and sea-level rise is an important management concern. Although these threats are well recognized, quantifying the integrated vulnerability is challenging due to the range of time and space scalesover which these processes act. Developing datasets and methods to identify the physical vulnerabilities of coastal environments due to storms and sea-level rise thus is an important scientific focus that supports land management decision making. Here we employ a Bayesian Network (BN) to model the interactions between geomorphic variables sampled from existing datasets that capture both storm-and sea-level rise related coastal evolution. The BN provides a means of estimating probabilities of changes in specific geomorphic characteristics such as foredune crest height, beach width, beach height, given knowledge of barrier island width, maximum barrier island elevation, distance from an inlet, the presence of anthropogenic modifications, and long-term shoreline change rates, which we assume to be directly related to sea-level rise. We evaluate BN skill and explore how different constraints, such as shoreline change characteristics (eroding, stable, accreting), distance to nearby inlets and island width, affect the probability distributions of future morphological characteristics. Our work demonstrates that a skillful BN can be constructed and that factors such as distance to inlet, shoreline change rate, and the presence of human alterations have the strongest influences on network performance. For Assateague Island, Maryland/Virginia, USA, we find that different shoreline change behaviors affect the probabilities of specific geomorphic characteristics, such as dune height, which allows us to identify vulnerable locations on the barrier island where habitat or infrastructure may be vulnerable to storms and sea-level rise.

  15. HgCdTe barrier infrared detectors

    Science.gov (United States)

    Kopytko, M.; Rogalski, A.

    2016-05-01

    In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar barriers. This idea has been also implemented in HgCdTe ternary material system. However, the implementation of this detector structure in HgCdTe material system is not straightforward due to the existence of a valence band discontinuity (barrier) at the absorber-barrier interface. In this paper we present status of HgCdTe barrier detectors with emphasis on technological progress in fabrication of MOCVD-grown HgCdTe barrier detectors achieved recently at the Institute of Applied Physics, Military University of Technology. Their performance is comparable with state-of-the-art of HgCdTe photodiodes. From the perspective of device fabrication their important technological advantage results from less stringent surface passivation requirements and tolerance to threading dislocations.

  16. Numerical simulations of capillary barrier field tests

    Energy Technology Data Exchange (ETDEWEB)

    Morris, C.E. [Univ. of Wollongong (Australia); Stormont, J.C. [Univ. of New Mexico, Albuquerque, NM (United States)

    1997-12-31

    Numerical simulations of two capillary barrier systems tested in the field were conducted to determine if an unsaturated flow model could accurately represent the observed results. The field data was collected from two 7-m long, 1.2-m thick capillary barriers built on a 10% grade that were being tested to investigate their ability to laterally divert water downslope. One system had a homogeneous fine layer, while the fine soil of the second barrier was layered to increase its ability to laterally divert infiltrating moisture. The barriers were subjected first to constant infiltration while minimizing evaporative losses and then were exposed to ambient conditions. The continuous infiltration period of the field tests for the two barrier systems was modelled to determine the ability of an existing code to accurately represent capillary barrier behavior embodied in these two designs. Differences between the field test and the model data were found, but in general the simulations appeared to adequately reproduce the response of the test systems. Accounting for moisture retention hysteresis in the layered system will potentially lead to more accurate modelling results and is likely to be important when developing reasonable predictions of capillary barrier behavior.

  17. Advances in research on labyrinth membranous barriers

    Institute of Scientific and Technical Information of China (English)

    Wenfang Sun; Wuqing Wang

    2015-01-01

    Integrity of the membranous labyrinth barrier system is of critical importance, which promotes inner ear homeostasis and maintains its features. The membranous labyrinth barrier system is divided into several subsets of barriers which, although independent from each other, are interrelated. The same substance may demonstrate different permeability characteristics through different barriers and under different conditions, while different substances can have different permeability features even in the same barrier under the same condition. All parts of the mem-branous labyrinth barrier structure, including their morphology, enzymes and channel proteins, and theirs permeability characteristics under various physiological and pathological conditions are reviewed in this paper. Infections, noise exposure, ototoxicity may all increase perme-ability of the barriers and lead to disturbances in inner ear homeostasis. Copyright © 2015 The Authors. Production & hosting by Elsevier (Singapore) Pte Ltd On behalf of PLA General Hospital Department of Otolaryngology Head and Neck Surgery. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  18. Permanent isolation surface barrier development plan

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1994-01-01

    The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no {open_quotes}proven{close_quotes} long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems.

  19. Statistical distributions

    CERN Document Server

    Forbes, Catherine; Hastings, Nicholas; Peacock, Brian J.

    2010-01-01

    A new edition of the trusted guide on commonly used statistical distributions Fully updated to reflect the latest developments on the topic, Statistical Distributions, Fourth Edition continues to serve as an authoritative guide on the application of statistical methods to research across various disciplines. The book provides a concise presentation of popular statistical distributions along with the necessary knowledge for their successful use in data modeling and analysis. Following a basic introduction, forty popular distributions are outlined in individual chapters that are complete with re

  20. Method for forming a barrier layer

    Energy Technology Data Exchange (ETDEWEB)

    Weihs, Timothy P. (Baltimore, MD); Barbee, Jr., Troy W. (Palo Alto, CA)

    2002-01-01

    Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

  1. Landfill Barrier-Overview and Prospect

    Institute of Scientific and Technical Information of China (English)

    Zheng Liange; Zhao Yongsheng

    2000-01-01

    Landfill is the primary method of waste disposal. The increasing attention focused on the effect of landfill on environment prompts the development of environmental sound landfill system. As the key parts of landfill, the barrier system can provide impermeabilization of leachate and prevent biogas from escaping intotheenvironment. In recent years, the technology pertaining the barrier system developed rapidly. In this paper, new materials used in liners and new concept of barrier construction are reviewed; the mechanisms of leachate through clay liner and geomembrane, the calculation of leaks through liner and the effect of freezing/thaw on liner are discussed.

  2. Wood-Based Paneling as Thermal Barriers,

    Science.gov (United States)

    1982-06-01

    Forest Panelingi as Products Laboratory Research Thermal Barriers Paper ’> FPL 408 10 C-D Li-J _ LzstZibutio iOse flh SQe.it s V 82 1012 048 |stract...this paper, a small scale horizontal exposure furnace test for testing thermal barriers over a calcium silicate board was added to the Uniform Building...Results," by Robert H. White. United States Department of - a eArclueWood-Based Agriculture Forest Paneling as Products Laboratory, Par Thermal Barriers PaperFPL

  3. Cultural Barriers to International Business Negotiations

    Institute of Scientific and Technical Information of China (English)

    刘竹林; 王俊

    2013-01-01

    Studies in international business negotiation acquire unprecedented significance, as globalization closely connects vari⁃ous business fields into a dynamic whole. Cultural factors play a vital role in international business negotiation. This paper begins with a brief introduction to business negotiation, international business negotiation and significance of cultural barriers to interna⁃tional business negotiation. It then explores two fundamental cultural differences of China and western countries:value differenc⁃es and thinking-pattern differences, which pose cultural barriers. The author then puts forward three strategies to help remove the cultural barriers and achieve successful negotiations.

  4. Reliability enhancement due to in-situ post-oxidation of sputtered MgO barrier in double MgO barrier magnetic tunnel junction

    Directory of Open Access Journals (Sweden)

    Chikako Yoshida

    2017-06-01

    Full Text Available We have investigated the effects of in-situ post-oxidation (PO of a sputtered MgO barrier in a double-MgO-barrier magnetic tunnel junction (MTJ and found that the short error rate was significantly reduced, the magnetoresistance (MR ratio was increased approximately 18%, and the endurance lifetime was extend. In addition, we found that the distribution of breakdown number (a measure of endurance exhibits trimodal characteristics, which indicates competition between extrinsic and intrinsic failures. This improvement in reliability might be related to the suppression of Fe and Co diffusion to the MgO barrier, as revealed by electron energy-loss spectroscopy (EELS analysis.

  5. Brain barrier systems: a new frontier in metal neurotoxicological research

    OpenAIRE

    Zheng, Wei; Aschner, Michael; Ghersi-Egea, Jean-Francois

    2003-01-01

    The concept of brain barriers or a brain barrier system embraces the blood–brain interface, referred to as the blood–brain barrier, and the blood–cerebrospinal fluid (CSF) interface, referred to as the blood–CSF barrier. These brain barriers protect the CNS against chemical insults, by different complementary mechanisms. Toxic metal molecules can either bypass these mechanisms or be sequestered in and therefore potentially deleterious to brain barriers. Supportive evidence suggests that damag...

  6. The Barrier Reef sediment apron: Tobacco Reef, Belize

    Science.gov (United States)

    MacIntyre, Ian G.; Graus, Richard R.; Reinthal, Peter N.; Littler, Mark M.; Littler, Diane S.

    1987-07-01

    Sedimentological and biological surveys of the back-reef sediment apron of Tobacco Reef, a continuous segment of the Belizean Barrier Reef, reveal five distinct biogeological zones: (1) coralline-coral- Dictyota pavement, (2) Turbinaria-Sargassum rubble, (3) Laurencia-Acanthophora sand and gravel, (4) bare sand and 95 Thalassia sand. These zones parallel the entire 9-km reef. The distribution of these zones is related to the spatial patterns of fish herbivory, the size of bottom sediments, and the stability of the substrate. Sedimentological and hydrodynamic studies indicate that most of the sediments in this area are transported from the reef crest and fore reef during periods of storm or hurricane activity and that their size distribution is largely the result of differential transport by high bottom-water velocities during those periods.

  7. Geographical Barriers Impeded the Spread of a Parasitic Chromosome.

    Directory of Open Access Journals (Sweden)

    María Inmaculada Manrique-Poyato

    Full Text Available Parasitic supernumerary (B chromosomes show high capability to spread across populations. But the existence of abrupt discontinuities in their distribution demands an explanation. The grasshopper Eyprepocnemis plorans plorans harbour supernumerary chromosomes in all natural populations hitherto analyzed from the Circum-Mediterranean region, with the single exception of the headwaters of the Iberian Segura River and several of its tributaries. To ascertain the causes of this distribution pattern, we analyze here the genetic structure of five natural populations collected in this zone (two +B and three -B, by means of ISSR markers. We found significant population structure, with two kinds of populations coinciding with +B and -B ones, separated by strong barriers to gene flow. This gives strong support to the hypothesis that the non-B populations precede B origin, and that B-carrying individuals from coastal zones have been able to colonize upstream areas, until geographical barriers (usually narrow canyons and arid areas surrounding them impeded their advance.

  8. Barrier formation at graded HgTe/CdTe heterojunctions

    Science.gov (United States)

    Goren, D.; Asa, G.; Nemirovsky, Y.

    1996-11-01

    Numerical calculations of graded HgTe/CdTe heterojunction (HJ) band diagrams at equilibrium are presented and discussed. The calculations are performed in the entire compositional range (0HJs are examined as a function of the graded region width and the graded region doping profiles. The graded region width and doping profiles were found to be the two main factors that determine whether barriers are formed as well as their shape and magnitude. The calculated results indicate that epitaxial ohmic HgTe contacts to extrinsic CdTe are possible, provided that the graded region is wider than one micron, and that it has the same doping type as the doping of the substrate with equal or higher absolute value. Further numerical calculations take into consideration the possible existence of distributed interface charges in the graded region of the HJ. It is shown that by assuming a classical transport over the potential barrier, the effective graded interface charge can be determined from the zero bias differential resistance of the HJ. Experimental transport measurements of metalorganic chemical vapor deposition (MOCVD) grown HgTe/p-CdTe graded HJs show a varying degree of rectification, indicating variations in the graded interface charge distributions which result from different MOCVD growth conditions.

  9. Market and Policy Barriers to Energy Storage Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, Dhruv [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Currier, Aileen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hernandez, Jacquelynne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ma, Ookie [Dept. of Energy (DOE), Washington DC (United States) Office of Energy Efficiency and Renewable Energy; Kirby, Brendan [Consultant

    2013-09-01

    Electric energy storage technologies can provide numerous grid services; there are a number of factors that restrict their current deployment. The most significant barrier to deployment is high capital costs, though several recent deployments indicate that capital costs are decreasing and energy storage may be the preferred economic alternative in certain situations. However, a number of other market and regulatory barriers persist, limiting further deployment. These barriers can be categorized into regulatory barriers, market (economic) barriers, utility and developer business model barriers, cross-cutting barriers and technology barriers.

  10. Distribution center

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Distribution center is a logistics link fulfill physical distribution as its main functionGenerally speaking, it's a large and hiahly automated center destined to receive goods from various plants and suppliers,take orders,fill them efficiently,and deliver goods to customers as quickly as possible.

  11. Breaching barriers to collaboration in public spaces

    DEFF Research Database (Denmark)

    Heinemann, Trine; Mitchell, Robb

    2014-01-01

    Technology provoking disparate individuals to collaborate or share experiences in the public space faces a difficult barrier, namely the ordinary social order of urban places. We employed the notion of the breaching experiment to explore how this barrier might be overcome. We analyse responses to...... of life in public spaces. Arising from this, we argue for the importance of qualities such as availability, facilitation, perspicuous settings, and perspicuous participants to encourage and support co-located strangers to collaborate and share experiences.......Technology provoking disparate individuals to collaborate or share experiences in the public space faces a difficult barrier, namely the ordinary social order of urban places. We employed the notion of the breaching experiment to explore how this barrier might be overcome. We analyse responses...

  12. Tsunami wave suppression using submarine barriers

    Energy Technology Data Exchange (ETDEWEB)

    Fridman, Aleksei M [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation); Alperovich, Leonid S; Pustil' nik, Lev A; Shtivelman, D [Department of Geophysics and Planetary Sciences, Tel-Aviv University (Israel); Shemer, L; Liberzon, D [School of Mechanical Engineering, Tel-Aviv University (Israel); Marchuk, An G [Institute of Computational Mathematics and Mathematical Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2010-11-15

    Submerged barriers, single or double, can be used to greatly reduce the devastating effect of a tsunami wave according to a research flume study conducted at Tel Aviv University. (instruments and methods of investigation)

  13. Headwater Stream Barriers in Western Oregon

    Data.gov (United States)

    Oak Ridge National Laboratory — This data set is an ArcInfo point coverage depicting barriers to fish migration in headwater basins in western Oregon. Data were compiled from reports by fisheries...

  14. Message maps for safety barrier awareness

    DEFF Research Database (Denmark)

    Jørgensen, Kirsten; Duijm, Nijs Jan; Troen, Hanne

    2011-01-01

    ’ performance parameters continuously, it is possible to create better risk awareness on the part of employers, managers and employees. Better risk awareness by these stakeholders will make it possible to: • acknowledge and continuously control risks; • discover and manage new risks; • keep safety barriers...... intact; • replace safety barriers with others, if necessary; • monitor and maintain the quality of safety barriers. This will contribute to maintain a high level of safety and prevent accidents. Some pro-active accident prevention can be obtained by making people aware of the risks in a given situation......, time, or place, and by enabling them to observe and judge whether the relevant safety barriers are in place and in good order. This can be considered “Situational Awareness” (SA), which is an essential competence enabling an employee to perform his/her job safely. This SA entails a number...

  15. Message maps for Safety Barrier Awareness

    DEFF Research Database (Denmark)

    ’ performance parameters continuously, it is possible to create better risk awareness of employers, managers and employees. Better risk awareness of these stakeholders will make it possible that: • Risks are acknowledged and controlled continuously; • New risks are discovered and managed; • Safety barriers...... are kept intact; • Safety barriers are replaced by other ones, if necessary • The quality of the safety barriers is monitored and maintained This will contribute to maintain a high level of safety and prevent accidents. Part of the pro-active accident prevention can be obtained by making people aware...... of the risks in a given situation, time or place, and by enabling them to observe and judge whether the relevant safety barriers are in place and in good order. This can be considered as “Situational Awareness (SA)”, which is an essential competence for at en employee can perform his/her job safely...

  16. Louisiana's barrier islands: A vanishing resource

    Science.gov (United States)

    List, Jefferey H.

    Louisiana's barrier islands are eroding so quickly that according to some estimates they will disappear by the end of this century. Although there is little human habitation on these islands, their erosion may have a severe impact on the environment landward of the barriers. As the islands disintegrate, the vast system of sheltered wetlands along Louisiana's delta plain are exposed to increasingly open Gulf conditions. Through the processes of increasing wave attack, salinity intrusion, storm surge, tidal range, and sediment transport, removal of the barrier islands may significantly accelerate deterioration of wetlands that have already experienced the greatest areal losses in the U.S. Because these wetlands are nurseries for many species of fish and shellfish, the loss of the barrier islands and the accelerated loss of the protected wetlands may have a profound impact in the billion dollar per year fishing industry supported by Louisiana's fragile coastal environment.

  17. DOE UST interim subsurface barrier technologies workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-09-01

    This document contains information which was presented at a workshop regarding interim subsurface barrier technologies that could be used for underground storage tanks, particularly the tank 241-C-106 at the Hanford Reservation.

  18. Great Smoky Mountains National Park Fish Barriers

    Data.gov (United States)

    National Park Service, Department of the Interior — Depicts physical barriers to fish movement within streams and rivers in GRSM. The EVENTTYPE attribute gives the type of restriction. Includes water falls and...

  19. Radon barrier: Method of testing airtightness

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn; Buch-Hansen, Thomas Cornelius

    2017-01-01

    The test method NBI 167/02 Radon membrane: Test of airtightness can be used for determining the airtightness of a radon barrier as a system solution. The test determines the air infiltration through the radon barrier for a number of levels of air pressure differences. The airflow through versus...... the difference in air pressure over the barrier is measured. The air pressure difference is kept constant, at a number of manually controlled levels. At each pressure level, the difference is measured in a single point close to the point where the suction for lowering the air pressure is located. Improvements...... to the test method were suggested. A digital stirring and control system, and a method for determining the mean air pressure difference, as well as a method for testing barriers with a very low air infiltration, were provided. The digital stirring and control system ensured automatic control and measuring...

  20. Communicating across barriers at home and abroad

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, J.W.

    1985-01-01

    This paper intends to catalyze the exchange of experience among technical communicators in meeting the challenge of communicating across a multitude of barriers: linguistic, disciplinary, cultural, political, intellectual, and emotional.

  1. Markers for blood-brain barrier integrity

    DEFF Research Database (Denmark)

    Saunders, Norman R; Dziegielewska, Katarzyna M; Møllgård, Kjeld;

    2015-01-01

    In recent years there has been a resurgence of interest in brain barriers and various roles their intrinsic mechanisms may play in neurological disorders. Such studies require suitable models and markers to demonstrate integrity and functional changes at the interfaces between blood, brain......, and cerebrospinal fluid. Studies of brain barrier mechanisms and measurements of plasma volume using dyes have a long-standing history, dating back to the late nineteenth-century. Their use in blood-brain barrier studies continues in spite of their known serious limitations in in vivo applications. These were well...... known when first introduced, but seem to have been forgotten since. Understanding these limitations is important because Evans blue is still the most commonly used marker of brain barrier integrity and those using it seem oblivious to problems arising from its in vivo application. The introduction...

  2. Thermal barrier coating for alloy systems

    Science.gov (United States)

    Seals, Roland D.; White, Rickey L.; Dinwiddie, Ralph B.

    2000-01-01

    An alloy substrate is protected by a thermal barrier coating formed from a layer of metallic bond coat and a top coat formed from generally hollow ceramic particles dispersed in a matrix bonded to the bond coat.

  3. Physical Environmental Barriers to School Attendance among ...

    African Journals Online (AJOL)

    Physical Environmental Barriers to School Attendance among Children with. Disabilities in two ... with learning, speech, cognitive, hearing, seeing, mo- bility and emotional, are ..... http://www.eenet.org.uk/theory (Accessed March. 2007). 26.

  4. Barriers restricting postpartum depression treatment in Chile

    National Research Council Canada - National Science Library

    Rojas, Graciela; Santelices, María Pía; Martínez, Pablo; Tomicic, Alemka; Reinel, Mahaira; Olhaberry, Marcia; Krause, Mariane

    2015-01-01

    In Chile, postpartum depression is a prevalent and disabling condition. Universal screening is available but has not been translated into better treatment rates, suggesting the existence of access barriers...

  5. ULTRA BARRIER TOPSHEET (UBT) FOR FLEXIBLE PHOTOVOLTAICS

    Energy Technology Data Exchange (ETDEWEB)

    DeScioli, Derek

    2013-06-01

    This slide-show presents 3M photovoltaic-related products, particularly flexible components. Emphasis is on the 3M Ultra Barrier Solar Films. Topics covered include reliability and qualification testing and flexible photovoltaic encapsulation costs.

  6. Vapor-barrier Vacuum Isolation System

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor); Taminger, Karen M. (Inventor)

    2014-01-01

    A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

  7. Skin barrier in atopic dermatitis: beyond filaggrin*

    Science.gov (United States)

    Zaniboni, Mariana Colombini; Samorano, Luciana Paula; Orfali, Raquel Leão; Aoki, Valéria

    2016-01-01

    Atopic dermatitis is a chronic inflammatory skin disease with a complex pathogenesis, where changes in skin barrier and imbalance of the immune system are relevant factors. The skin forms a mechanic and immune barrier, regulating water loss from the internal to the external environment, and protecting the individual from external aggressions, such as microorganisms, ultraviolet radiation and physical trauma. Main components of the skin barrier are located in the outer layers of the epidermis (such as filaggrin), the proteins that form the tight junction (TJ) and components of the innate immune system. Recent data involving skin barrier reveal new information regarding its structure and its role in the mechanic-immunological defense; atopic dermatitis (AD) is an example of a disease related to dysfunctions associated with this complex. PMID:27579743

  8. Tantalum oxide barrier in magnetic tunnel junctions

    Institute of Scientific and Technical Information of China (English)

    Guanghua Yu; Tingting Ren; Wei Ji; Jiao Teng; Fengwu Zhu

    2004-01-01

    Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier.The experimental results show that the chemical state of tantalum is pure Ta5+ and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound,NiTa2. A magnetic "dead layer" could be produced in the NiFe/Ta interface. The "dead layer" is likely to influence the spinning electron transport and the magnetoresistance effect.

  9. Evapotranspiration studies for protective barriers: Experimental plans

    Energy Technology Data Exchange (ETDEWEB)

    Link, S.O.; Waugh, W.J.

    1989-11-01

    This document describes a general theory and experimental plans for predicting evapotranspiration in support of the Protective Barrier Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. 45 refs., 1 fig., 4 tabs.

  10. The Glomerular Filtration Barrier: Components and Crosstalk

    Directory of Open Access Journals (Sweden)

    Madhav C. Menon

    2012-01-01

    Full Text Available The glomerular filtration barrier is a highly specialized blood filtration interface that displays a high conductance to small and midsized solutes in plasma but retains relative impermeability to macromolecules. Its integrity is maintained by physicochemical and signalling interplay among its three core constituents—the glomerular endothelial cell, the basement membrane and visceral epithelial cell (podocyte. Understanding the pathomechanisms of inherited and acquired human diseases as well as experimental injury models of this barrier have helped to unravel this interdependence. Key among the consequences of interference with the integrity of the glomerular filtration barrier is the appearance of significant amounts of proteins in the urine. Proteinuria correlates with kidney disease progression and cardiovascular mortality. With specific reference to proteinuria in human and animal disease phenotypes, the following review explores the roles of the endothelial cell, glomerular basement membrane, and the podocyte and attempts to highlight examples of essential crosstalk within this barrier.

  11. Barriers of Reproductive Health Education in Schools

    National Research Council Canada - National Science Library

    Tahereh Kamalikhah; Fatemeh Rahmati-Najarkolaei; Masoud Karimi

    2012-01-01

    Background: The aim of this study is to explore the barriers on reproductive health education and prospects among teachers and students in the Zahedan city related to reproductive health education at schools...

  12. Barrier Li Quantum Dots in Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    LIUYi-Min; LIXiao-Zhu; YANWen-Hong; BAOCheng-Guang

    2003-01-01

    The methods for the few-body system are introduced to investigate the states of the barrier Li quantum dots (QDs) in an arbitrary strength of magnetic field. The configuration, which consists of a positive ion located on the z-axis at a distaneed from the two-dimensional QD plane (the x-y plane) and three electrons in the dot plane bound by the positive ion, is called a barrier Li center. The system, which consists of three electrons in the dot plane bound by the ion,is called a barrier Li QD. The dependence of energy of the state of the barrier Li QD on an external magnetic field B and the distance d is obtained. The angular momentum L of the ground states is found to jump not only with the variation orB but also with d.

  13. Photovoltaic and thermophotovoltaic devices with quantum barriers

    Science.gov (United States)

    Wernsman, Bernard R.

    2007-04-10

    A photovoltaic or thermophotovoltaic device includes a diode formed by p-type material and n-type material joined at a p-n junction and including a depletion region adjacent to said p-n junction, and a quantum barrier disposed near or in the depletion region of the p-n junction so as to decrease device reverse saturation current density while maintaining device short circuit current density. In one embodiment, the quantum barrier is disposed on the n-type material side of the p-n junction and decreases the reverse saturation current density due to electrons while in another, the barrier is disposed on the p-type material side of the p-n junction and decreases the reverse saturation current density due to holes. In another embodiment, both types of quantum barriers are used.

  14. Storm impacts on small barrier islands

    DEFF Research Database (Denmark)

    Kroon, Aart; Fruergaard, Mikkel

    The shorelines of the Baltic Sea and the inner coastal waters in Denmark consist of many barrier islands. These sandy barrier islands were mainly formed in the Holocene and are still very dynamic. The present day changes in the morphology are dominantly governed by storm waves and associated high...... changes in this evolution due to changes in the climate and associated sea levels. We analyzed the morphologic evolution of a series of barrier islands over the last decades using maps, aerial photographs and satellite images. This decadal morphologic evolution was coupled to the frequency and intensity...... of the local extreme events. The characterization of the extreme events was based on the joint probability of the extreme water levels and storm waves for the specific sites. The predicted climate change for the Danish waters will lead to higher water levels and an increase of the overwashes on the barrier...

  15. Railway noise barriers: Measurements and Simulations

    OpenAIRE

    Ausejo Prieto, Miguel; Recuero López, Manuel; Fausti, Patrizio; Cremonini, Renzo

    2009-01-01

    Trains Trains passages passages generate generate aa very very annoying annoying noise noise toto the the inhabitants inhabitants ofof their their environs environs.. To To reduce reduce this this annoyance annoyance, noise noise barriers barriers are are installed installed near near several several railway railway lines lines.. Nowadays Nowadays, acoustic acoustic simulation simulation programs programs are are used used inin order order toto optimize optimize the the design design ofof the...

  16. Barrier Mechanisms in the Developing Brain

    OpenAIRE

    Saunders, Norman R.; Liddelow, Shane A.; Dziegielewska, Katarzyna M.

    2012-01-01

    The adult brain functions within a well-controlled stable environment, the properties of which are determined by cellular exchange mechanisms superimposed on the diffusion restraint provided by tight junctions at interfaces between blood, brain and cerebrospinal fluid (CSF). These interfaces are referred to as “the” blood–brain barrier. It is widely believed that in embryos and newborns, this barrier is immature or “leaky,” rendering the developing brain more vulnerable to drugs or toxins ent...

  17. Frozen soil barriers for hazardous waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    Dash, J.G.; Leger, R. [Univ. of Washington, Seattle, WA (United States); Fu, H.Y. [Univ. of California, Santa Barbara, CA (United States)

    1997-12-31

    Laboratory and full field measurements have demonstrated the effectiveness of artificial ground freezing for the containment of subsurface hazardous and radioactive wastes. Bench tests and a field demonstration have shown that cryogenic barriers are impenetrable to aqueous and non aqueous liquids. As a result of the successful tests the US Department of Energy has designated frozen ground barriers as one of its top ten remediation technologies.

  18. LANGUAGE BARRIERS: FEEDBACK FROM THE IT INDUSTRY

    OpenAIRE

    Sareen Kaur Bhar; Nor Azlah Abu Bakar

    2013-01-01

    Meaningful interaction process between human beings necessitates effective communication especially in organisations that have rapid information exchange demands. It is perceived that most IT organisations that face communication and language barriers have lost businesses due to higher product defect rates, lack of focus on business objectives, stifled innovation and dissatisfied customers and poor customer services. This study looks at the language barriers faced by employees working in var...

  19. Immigrant language barriers and house prices

    OpenAIRE

    Andreas M. Fischer

    2011-01-01

    Are language skills important in explaining the nexus between house prices and immigrant inflows? The language barrier hypothesis says immigrants from a non common language country value amenities more than immigrants from common language countries.> ; In turn, immigrants from non common language countries are less price sensitive to house price changes than immigrants from a common language country. Tests of the language barrier hypothesis with Swiss house prices show that an immigration inf...

  20. The interaction between tide and salinity barriers

    Directory of Open Access Journals (Sweden)

    Patchanok Srivihok

    2003-11-01

    Full Text Available Presently, there is a number of salinity barrier utilization and this kind of structure becomes more common in estuarine areas. However, the construction of barrier at the river mouth or inside the river results in amplification of tide due to creation of standing tide at the barrier. This standing tide creates two major problems, namely, the overspill of salinewater during high water and bank erosion during low water along the tidal reach downstream of the barrier. In this study, the analytical model is developed to determine the river hydraulic behaviors which affects by tide, river flow and barrier structure of the Bang Pakong River, Thailand. The analytical model of tide and river flow of the Chao Phraya River is adopted and adjusted to determine the tide characteristics modified by river flow. Moreover, the analytical model of tide and salinity barrier would then be developed by cooperating of the analytical model of tide and river flow interaction together with tidal flow cooscillating tide theory. It is found from this study that the analytical model of the Chao Phraya River which is suitable for high freshwater discharge underestimates damping modulus and friction slope which requires adjustment for low freshwater discharge of the Bang Pakong River. The analytical model of tide and salinity barrier can be finally used to predict the water level downstream of the barrier. The model overestimated the water level fluctuation during the unsteady flow from upstream which may be because of the assumption of steady flow condition in the model development due to limited data available after the construction.

  1. Barriers and strategies in listening comprehension

    Institute of Scientific and Technical Information of China (English)

    张帆; 张金萍; 李爱娜

    2006-01-01

    A variety of barriers to listening comprehension are illustrated in this paper. They are analyzed respectively and several effective strategies are also presented afterward. The barriers to listening are those of psychological quality, language knowledge, cultural background, Chinese interference and so on. The strategies should be as follows: training students' psychological quality,strengthening the teaching and learning of language knowledge,comparing cultural differences, using student-centered teaching method and combining intensive listening and extensive listening.

  2. Overcoming Affective Barriers in College English Learning

    Institute of Scientific and Technical Information of China (English)

    任永东

    2014-01-01

    Nowadays, the development of economy as well as the progress of society requires better English competence of col-lege students. As a result, a large number of college students are obsessedby affective barriers in their English learning, especially when they have to cope with CET 4 or CET 6, which is more and more difficult. This paper focuses on how to help college stu-dents overcome their affective barriers more effectively to improve their English learning.

  3. Structural Stability of Tokamak Equilibrium: Transport Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Solano, E. R.

    2001-07-01

    A generalised theory of structural stability of differential equations is introduced and applied to the Grad-Shafranov equation. It is discussed how the formation and loss of transport barrier could be associated with the appearance/disappearance of equilibria. The equilibrium conjecture is presented: transport barriers are associated with locally diamagnetic regions in the plasma, and affected by the paramagnetism of the bootstrap current. (Author) 18 refs.

  4. Use of element model to evaluate transmissibility reduction due to barriers

    Energy Technology Data Exchange (ETDEWEB)

    Svanes, T.; South, D.; Dronen, O.M. [Statoil, Bergen (Norway)

    1997-08-01

    Water breakthrough has been observed a year earlier than expected in the productive Oseberg Formation in the Veslefrikk Field. Production data revealed extensive water override, whereas the opposite situation was expected based on a homogeneous and coarse flow simulation model. A new model was developed to include geological heterogeneities using a simple upscaling method. The Oseberg Fm. consists of an upper homogeneous unit (zone 2) and a lower unit containing thin barriers of shale and calcite cemented sandstone (zone 1). The barrier content varies laterally. When barriers are distributed in a complex 3D pattern, they reduce the upscaled horizontal transmissibility more than what is obtained by multiplying the sand permeability by the net-to-gross ratio (N/G). However, the transmissibility reduction strongly depends on the spatial distribution of barriers and their geometry. Therefore, a fine scale element model was used to derive the average transmissibility reduction as a function of N/G for alternative geological descriptions of the barriers. A geo-statistical method called General Marked Point Process was used to generate the fine scale descriptions. This work has resulted in a simple upscaling routine for horizontal transmissibility, which represents an effective bridge between geological evaluation of uncertainties and fluid flow simulation. The method combines geo-statistical and deterministic modelling in an elegant manner, recognising that most often these methods complement one another.

  5. Implementation of the modified Monte Carlo simulation for evaluate the barrier option prices

    Directory of Open Access Journals (Sweden)

    Kazem Nouri

    2017-03-01

    Full Text Available In this paper, we apply an improved version of Monte Carlo methods to pricing barrier options. This kind of options may match with risk hedging needs more closely than standard options. Barrier options behave like a plain vanilla option with one exception. A zero payoff may occur before expiry, if the option ceases to exist; accordingly, barrier options are cheaper than similar standard vanilla options. We apply a new Monte Carlo method to compute the prices of single and double barrier options written on stocks. The basic idea of the new method is to use uniformly distributed random numbers and an exit probability in order to perform a robust estimation of the first time the stock price hits the barrier. Using uniformly distributed random numbers decreases the estimation of first hitting time error in comparison with standard Monte Carlo or similar methods. It is numerically shown that the answer of our method is closer to the exact value and the first hitting time error is reduced.

  6. Free energy and hidden barriers of the β-sheet structure of prion protein.

    Science.gov (United States)

    Paz, S Alexis; Abrams, Cameron F

    2015-10-13

    On-the-fly free-energy parametrization is a new collective variable biasing approach akin to metadynamics with one important distinction: rather than acquiring an accelerated distribution via a history-dependent bias potential, sampling on this distribution is achieved from the beginning of the simulation using temperature-accelerated molecular dynamics. In the present work, we compare the performance of both approaches to compute the free-energy profile along a scalar collective variable measuring the H-bond registry of the β-sheet structure of the mouse Prion protein. Both methods agree on the location of the free-energy minimum, but free-energy profiles from well-tempered metadynamics are subject to a much higher degree of statistical noise due to hidden barriers. The sensitivity of metadynamics to hidden barriers is shown to be a consequence of the history dependence of the bias potential, and we detail the nature of these barriers for the prion β-sheet. In contrast, on-the-fly parametrization is much less sensitive to these barriers and thus displays improved convergence behavior relative to that of metadynamics. While hidden barriers are a frequent and central issue in free-energy methods, on-the-fly free-energy parametrization appears to be a robust and preferable method to confront this issue.

  7. ELECTROSTATICALLY ENHANCED BARRIER FILTER COLLECTION

    Energy Technology Data Exchange (ETDEWEB)

    John Erjavec; Michael D. Mann; Ryan Z. Knutson; Michael L. Swanson; Michael E. Collings

    2003-06-01

    electrostatically enhanced barrier filter collection (EBFC). This concept combines electrostatic precipitation (ESP) with candle filters in a single unit. Similar technology has been recently proven on a commercial scale for atmospheric applications, but needed to be tested at high temperatures and pressures. The synergy obtained by combining the two control technologies into a single system should actually reduce filter system capital and operating costs and make the system more reliable. More specifically, the ESP is expected to significantly reduce candle filter load and also to limit ash reintrainment, allowing for full recovery of baseline pressure drop during backpulsing of the filters.

  8. Model assessment of protective barriers: Part 3

    Energy Technology Data Exchange (ETDEWEB)

    Fayer, M.J.; Rockhold, M.L.; Holford, D.J.

    1992-02-01

    Radioactive waste exists at the US Department of Energy's (DOE's) Hanford Site in a variety of locations, including subsurface grout and tank farms, solid waste burial grounds, and contaminated soil sites. Some of these waste sites may need to be isolated from percolating water to minimize the potential for transport of the waste to the ground water, which eventually discharges to the Columbia River. Multilayer protective barriers have been proposed as a means of limiting the flow of water through the waste sites (DOE 1987). A multiyear research program (managed jointly by Pacific Northwest Laboratory (PNL) and Westinghouse Hanford Company for the DOE) is aimed at assessing the performance of these barriers. One aspect of this program involves the use of computer models to predict barrier performance. Three modeling studies have already been conducted and a test plan was produced. The simulation work reported here was conducted by PNL and extends the previous modeling work. The purpose of this report are to understand phenomena that have been observed in the field and to provide information that can be used to improve hydrologic modeling of the protective barrier. An improved modeling capability results in better estimates of barrier performance. Better estimates can be used to improve the design of barriers and the assessment of their long-term performance.

  9. Addressing language barriers to healthcare in India.

    Science.gov (United States)

    Narayan, Lalit

    2013-01-01

    In spite of a growing recognition of the importance of doctor-patient communication, the issue of language barriers to healthcare has received very little attention in India. The Indian population speaks over 22 major languages with English used as the lingua franca for biomedicine. Large-scale internal migration has meant that health workers are encountering increasing instances of language discordance within clinical settings. Research done predominantly in the West has shown language discordance to significantly affect access to care, cause problems of comprehension and adherence, and decrease the satisfaction and quality of care. Addressing language barriers to healthcare in India requires a stronger political commitment to providing non-discriminatory health services, especially to vulnerable groups such as illiterate migrant workers. Research will have to address three broad areas: the ways in which language barriers affect health and healthcare, the efficacy of interventions to overcome language barriers, and the costs of language barriers and efforts to overcome them. There is a need to address such barriers in health worker education and clinical practice. Proven strategies such as hiring multilingual healthcare workers, providing language training to health providers, employing in situ translators or using telephone interpretation services will have to be evaluated for their appropriateness to the Indian context. Internet-based initiatives, the proliferation of mobile phones and recent advances in machine translation promise to contribute to the solution. Copyright 2013, NMJI.

  10. An overview on novel thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Thermal barrier coatings (TBCs) offer the potential to significantly improve efficiencies of aero engines as well as stationary gas turbines for power generation. On internally cooled turbine parts, temperature gradients of the order of 100-150℃ can be achieved. TBCs, typically consisting of an yttrium stabilized zirconia top coat and a metallic bond coat deposited onto a superalloy substrate, are mainly used to extend lifetime. Further efficiency improvements require TBCs being an integral part of the component which requires reliable and predictable TBC performance. TBCs produced by electron beam physical vapor deposition (EbPVD) or plasma spray (PS) deposition are favored for high performance applications. The paper highlights critical R&D needs for advanced TBC systems with a special focus on reduced thermal conductivity and life prediction needs. To further enhance the efficiency of gas turbines, higher temperature and a longer lifetime of the coating are needed for the next generation of TBCs. This paper presents the development of new materials, new deposition technologies, and new concept for application as novel TBCs. This paper summarizes the basic properties of conventional thermal barrier coatings. Based on our own investigation, we reviewed the progress on materials and technologies of novel thermal barrier coatings. Except yttria stabilized zirconia, other materials such as lanthanum zirconate and rare earth oxides are also promising materials for thermal barrier coatings. Nanostructure thermal barrier coating is presented as a new concept. This paper also summarizes the technologies for depositing the thermal barrier coatings.

  11. Field study plan for alternate barriers

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, H.D.; Gee, G.W.; Relyea, J.F.

    1989-05-01

    Pacific Northwest Laboratory (PNL) is providing technical assistance in selecting, designing, evaluating, and demonstrating protective barriers. As part of this technical assistance effort, asphalt, clay, and chemical grout will be evaluated for use as alternate barriers. The purpose of the subsurface layer is to reduce the likelihood that extreme events (i.e., 100-year maximum storms, etc.) will cause significant drainage through the barrier. The tests on alternate barriers will include laboratory and field analysis of the subsurface layer performance. This field test plan outlines the activities required to test and design subsurface moisture barriers. The test plan covers activities completed in FY 1988 and planned through FY 1992 and includes a field-scale test of one or more of the alternate barriers to demonstrate full-scale application techniques and to provide performance data on a larger scale. Tests on asphalt, clay, and chemical grout were initiated in FY 1988 in small (30.5 cm diameter) tube-layer lysimeters. The parameters used for testing the materials were different for each one. The tests had to take into account the differences in material characteristics and response to change in conditions, as well as information provided by previous studies. 33 refs., 8 figs., 1 tab.

  12. The Infant Skin Barrier: Can We Preserve, Protect, and Enhance the Barrier?

    OpenAIRE

    Telofski, Lorena S.; A. Peter Morello; Catherine Mack Correa, M.; Georgios N. Stamatas

    2012-01-01

    Infant skin is different from adult in structure, function, and composition. Despite these differences, the skin barrier is competent at birth in healthy, full-term neonates. The primary focus of this paper is on the developing skin barrier in healthy, full-term neonates and infants. Additionally, a brief discussion of the properties of the skin barrier in premature neonates and infants with abnormal skin conditions (i.e., atopic dermatitis and eczema) is included. As infant skin continues to...

  13. Determining collective barrier operation skew in a parallel computer

    Energy Technology Data Exchange (ETDEWEB)

    Faraj, Daniel A.

    2015-11-24

    Determining collective barrier operation skew in a parallel computer that includes a number of compute nodes organized into an operational group includes: for each of the nodes until each node has been selected as a delayed node: selecting one of the nodes as a delayed node; entering, by each node other than the delayed node, a collective barrier operation; entering, after a delay by the delayed node, the collective barrier operation; receiving an exit signal from a root of the collective barrier operation; and measuring, for the delayed node, a barrier completion time. The barrier operation skew is calculated by: identifying, from the compute nodes' barrier completion times, a maximum barrier completion time and a minimum barrier completion time and calculating the barrier operation skew as the difference of the maximum and the minimum barrier completion time.

  14. New treatments for restoring impaired epidermal barrier permeability: skin barrier repair creams.

    Science.gov (United States)

    Draelos, Zoe Diana

    2012-01-01

    Skin health depends on an intact barrier composed of protein-rich corneocytes surrounded by the lamellar intercellular lipids. This barrier provides waterproof protection for the body, preventing infection, regulating electrolyte balance, maintaining body temperature, and providing a mechanism for sensation. Damage to the skin barrier results in skin disease that can be treated by a variety of externally applied substances, such as ceramides, hyaluronic acid, licorice extracts, dimethicone, petrolatum, and paraffin wax. These substances are found in moisturizers that are sold as cosmetics and in prescriptions as 510(k) devices. This contribution examines the formulation and effect of skin barrier creams.

  15. Geographically weighted regression as a generalized Wombling to detect barriers to gene flow.

    Science.gov (United States)

    Diniz-Filho, José Alexandre Felizola; Soares, Thannya Nascimento; de Campos Telles, Mariana Pires

    2016-08-01

    Barriers to gene flow play an important role in structuring populations, especially in human-modified landscapes, and several methods have been proposed to detect such barriers. However, most applications of these methods require a relative large number of individuals or populations distributed in space, connected by vertices from Delaunay or Gabriel networks. Here we show, using both simulated and empirical data, a new application of geographically weighted regression (GWR) to detect such barriers, modeling the genetic variation as a "local" linear function of geographic coordinates (latitude and longitude). In the GWR, standard regression statistics, such as R(2) and slopes, are estimated for each sampling unit and thus are mapped. Peaks in these local statistics are then expected close to the barriers if genetic discontinuities exist, capturing a higher rate of population differentiation among neighboring populations. Isolation-by-Distance simulations on a longitudinally warped lattice revealed that higher local slopes from GWR coincide with the barrier detected with Monmonier algorithm. Even with a relatively small effect of the barrier, the power of local GWR in detecting the east-west barriers was higher than 95 %. We also analyzed empirical data of genetic differentiation among tree populations of Dipteryx alata and Eugenia dysenterica Brazilian Cerrado. GWR was applied to the principal coordinate of the pairwise FST matrix based on microsatellite loci. In both simulated and empirical data, the GWR results were consistent with discontinuities detected by Monmonier algorithm, as well as with previous explanations for the spatial patterns of genetic differentiation for the two species. Our analyses reveal how this new application of GWR can viewed as a generalized Wombling in a continuous space and be a useful approach to detect barriers and discontinuities to gene flow.

  16. Barriers and challenges in researches by Iranian students of medical universities

    Directory of Open Access Journals (Sweden)

    Zohreh Anbari

    2015-01-01

    Full Text Available Background: Health sciences research (HSR is an essential part of improving health care which plays a critical role in the field of medicine and clinical practice. The aim of the current study was to assess barriers to the research by students of medical sciences as well as to find out effective strategies for management of student researches in Iranian universities. Materials and Methods: This study utilized a hybrid design with quantitative and qualitative analytical approaches conducted on 627 students in six schools of medical sciences in two universities in Central Province in Iran from April to December, 2012. Questionnaires were distributed among researcher and non-researcher students to find barriers to the research. These barriers were approved and validated by similar studies and strategies using the Delphi technique on 36 students. Results: The most important barriers among researcher students were institutional barriers (3.3 ± 1.3, but in non-researcher students they were individual barriers (3.6 ± 1.7. The majority of barriers to involvement in the research among researcher students appeared to be time, lack of access to electronic resources and prolongation of the process of buying equipment. In addition, the greatest barriers among non-researcher students included the lack of time, scientific writing skills, and access to trained assistants. Conclusion: The results showed the issue of attitudes towards compulsory research as a component of critical scholarship in the curriculum of medical courses. Moreover, employment of the research experts can be helpful for research training in schools of medical sciences.

  17. Heterogeneous delivery is a barrier to the translational advancement of oncolytic virotherapy for treating solid tumors

    Directory of Open Access Journals (Sweden)

    Miller AC

    2014-07-01

    Full Text Available Amber C Miller,1,2 Stephen J Russell2,3 1Mayo Graduate School, Mayo Clinic, Rochester, Minnesota, USA; 2Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA; 3Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA Abstract: Oncolytic viruses are a promising experimental anticancer therapy currently undergoing clinical translation. The development of oncolytic virotherapy offers a potential solution to the elusive “one-shot”cancer cure by providing targeted therapy to selectively infect and kill cancer cells while provoking adaptive anticancer immune responses as protection against distant metastasis and recurrent tumor challenge. While this technology has overcome barriers to safety and efficacy through cancer-specific targeting techniques, in order to reach full therapeutic potential, oncolytic therapies must still overcome barriers to intratumoral delivery and spread that result in heterogeneous intratumoral delivery and nonuniform response. This review will discuss barriers to oncolytic virotherapy translation related to mechanisms of delivering virus via tumor vasculature and distributing virus throughout the tumor microenvironment. Barriers include extravasation into the tumor that is dependent on adequate blood flow, tissue perfusion, and tumoral enhanced permeability and retention for transvascular transport. Subsequently, virions must undergo interstitial transport against dense stromal barriers and high interstitial fluid pressure to initiate infection. In order to achieve massive tumor regression, infection must spread to cover large volumes of tumor mass. Furthermore, virus bioavailability is quickly dampened upon systemic administration due to neutralization and sequestration. These barriers to delivery limit the amount of virus that effectively reaches and spreads within the tumor, forcing dose increases that impinge upon limits of production and increase possibility of adverse

  18. MAIL DISTRIBUTION

    CERN Multimedia

    Mail Office

    2001-01-01

    PLEASE NOTE: changed schedule for mail distribution on 21 December 2001 afternoon delivery will be one hour earlier than usual, delivery to LHC sites will take place late morning. Thank you for your understanding.

  19. Stable distributions

    CERN Document Server

    Janson, Svante

    2011-01-01

    We give some explicit calculations for stable distributions and convergence to them, mainly based on less explicit results in Feller (1971). The main purpose is to provide ourselves with easy reference to explicit formulas. (There are no new results.)

  20. Spatial distribution

    DEFF Research Database (Denmark)

    Borregaard, Michael Krabbe; Hendrichsen, Ditte Katrine; Nachman, Gøsta Støger

    2008-01-01

    Living organisms are distributed over the entire surface of the planet. The distribution of the individuals of each species is not random; on the contrary, they are strongly dependent on the biology and ecology of the species, and vary over different spatial scale. The structure of whole...... populations reflects the location and fragmentation pattern of the habitat types preferred by the species, and the complex dynamics of migration, colonization, and population growth taking place over the landscape. Within these, individuals are distributed among each other in regular or clumped patterns......, depending on the nature of intraspecific interactions between them: while the individuals of some species repel each other and partition the available area, others form groups of varying size, determined by the fitness of each group member. The spatial distribution pattern of individuals again strongly...

  1. Distributed optimality

    OpenAIRE

    Trommer, Jochen

    2005-01-01

    In dieser Dissertation schlage ich eine Synthese (Distributed Optimality, DO) von Optimalitätstheorie und einem derivationellen, morphologischem Asatz, Distributed Morphology (DM; Halle & Marantz, 1993) vor. Durch die Integration von OT in DM wird es möglich, Phänomene, die in DM durch sprachspezifische Regeln oder Merkmale von lexikalischen Einträge erfasst werden, auf die Interaktion von verletzbaren, universellen Constraints zurückzuführen. Andererseits leistet auch DM zwei substantielle B...

  2. Distributed Subtyping

    OpenAIRE

    Baehni, Sébastien; Barreto, Joao; Guerraoui, Rachid

    2006-01-01

    One of the most frequent operations in object-oriented programs is the "instanceof" test, also called the "subtyping" test or the "type inclusion" test. This test determines if a given object is an instance of some type. Surprisingly, despite a lot of research on distributed object-oriented languages and systems, almost no work has been devoted to the implementation of this test in a distributed environment. This paper presents the first algorithm to implement the "subtyping" test on an obje...

  3. The dividend function in the jump-diffusion dual model with barrier dividend strategy

    Institute of Scientific and Technical Information of China (English)

    LI Bo; WU Rong

    2008-01-01

    A dual model of the perturbed classical compound Poisson risk model is considered under a constant dividend barrier.A new method is used in deriving the boundary condition of the equation for the expectation function by studying the local time of a related process.We obtain the expression for the expected discount dividend function in terms of those in the corresponding perturbed compound Poisson risk model without barriers.A special case in which the gain size is phase-type distributed is illustrated.We also consider the existence of the optimal dividend level.

  4. On the Traversal Time of Barriers

    Science.gov (United States)

    Aichmann, Horst; Nimtz, Günter

    2014-06-01

    Fifty years ago Hartman studied the barrier transmission time of wave packets (J Appl Phys 33:3427-3433, 1962). He was inspired by the tunneling experiments across thin insulating layers at that time. For opaque barriers he calculated faster than light propagation and a transmission time independent of barrier length, which is called the Hartman effect. A faster than light (FTL or superluminal) wave packet velocity was deduced in analog tunneling experiments with microwaves and with infrared light thirty years later. Recently, the conjectured zero time of electron tunneling was claimed to have been observed in ionizing helium inside the barrier. The calculated and measured short tunneling time arises at the barrier front. This tunneling time was found to be universal for elastic fields as well as for electromagnetic fields. Remarkable is that the delay time is the same for the reflected and the transmitted waves in the case of symmetric barriers. Several theoretical physicists predicted this strange nature of the tunneling process. However, even with this background many members of the physics community do not accept a FTL signal velocity interpretation of the experimental tunneling results. Instead a luminal front velocity was calculated to explain the FTL experimental results frequently. However, Brillouin stated in his book on wave propagation and group velocity that the front velocity is given by the group velocity of wave packets in the case of physical signals, which have only finite frequency bandwidths. Some studies assumed barriers to be cavities and the observed tunneling time does represent the cavity lifetime. We are going to discus these continuing misleading interpretations, which are found in journals and in textbooks till today.

  5. Circularly polarized antennas for active holographic imaging through barriers

    Science.gov (United States)

    McMakin, Douglas L [Richland, WA; Severtsen, Ronald H [Richland, WA; Lechelt, Wayne M [West Richland, WA; Prince, James M [Kennewick, WA

    2011-07-26

    Circularly-polarized antennas and their methods of use for active holographic imaging through barriers. The antennas are dielectrically loaded to optimally match the dielectric constant of the barrier through which images are to be produced. The dielectric loading helps to remove barrier-front surface reflections and to couple electromagnetic energy into the barrier.

  6. A Learner Perspective on Barriers to E-Learning

    Science.gov (United States)

    Becker, Karen; Newton, Cameron; Sawang, Sukanlaya

    2013-01-01

    This study aims to identify and categorize barriers to e-learning adoption and the relative impact of those barriers on learners. It contributes to the understanding of learner perceptions of barriers, the different types of barriers and their relative importance. This study used a quantitative methodology grounded in previous literature. The…

  7. A Factor Analysis of Barriers to Effective Listening.

    Science.gov (United States)

    Golen, Steven

    1990-01-01

    Conducts a factor analysis to determine listening barriers perceived as most frequently affecting the listening effectiveness among business college students. Finds the presence of six listening barriers, with the barrier "listen primarily for details or facts" as the most frequently encountered barrier perceived by students. (MM)

  8. Morphological changes of blood spleen barrier in portal hypertensive spleen

    Institute of Scientific and Technical Information of China (English)

    LI Zong-fang; ZHANG Shu; HUANG Ying; XIA Xian-ming; LI Ai-min; PAN Dun; ZHANG Wei; WANG Juan

    2008-01-01

    Background The pathogenesis of hypersplenism and the immune function of the spleen in patients with portal hypertension(PH)remain obscure.This study aimed to evaluate the morphological changes of blood spleen barrier in spleen with hypersplenism due to PH and provide evidence for an in-depth investigation of the immune function of the spleen with hypersplenism and the mechanism of hypersplenism.Methods Spleen samples from 12 portal hypertensive patients and 4 patients with traumatic ruptures of spleen were examined.The samples of spleen were made into pathological sections,stained with Masson trichrome stain,Gomori stain,and CD68,CD34 immunohistochemistry,and were examined microscopically for the changes in the distribution of collagen fibers,reticular fibers,macrophages,and vascular endothelial cells.The changes in ultrastructure of macrophages and endothelial cells in marginal zone were also evaluated by transmission electron microscopy.Results As compared to the normal spleen,the density of macrophage in the PH spleen was decreased,but the macrophages were mainly located in the marginal zone and distributed around the splenic corpuscle,with many villi and pseudopodium-like protrusion on the cell surface.The accrementition of collagen fibers was obvious around the splenic corpuscle and central artery.The increased reticulate fibers encircled the splenic corpuscle with more connection between the fibers.The vascular endothelial cells were in diffused distribution,without any regionality in PH spleen,but the vessel with enlarged lumina increased in red pulp.Conclusions The morphological changes of the blood spleen barrier can be one of the pathological fundaments for the abnormality of the immune function and the increased destruction of blood cells located in the spleens of patients with PH.However,this still entails clarification.

  9. An insight into the performance of road barriers - redistribution of barrier-relevant crashes.

    Science.gov (United States)

    Zou, Yaotian; Tarko, Andrew P

    2016-11-01

    Unlike most of traffic safety treatments that prevent crashes, road barriers reduce the severity of crash outcomes by replacing crashes with a high risk of severe injury and fatality (such as median crossover head-on collisions or collisions with high-hazard objects) with less risky events (such as collisions with barriers). This "crash conversion" is actually more complex than one-to-one replacement and it has not been studied yet. The published work estimated the reduction of selected types of crashes (typically, median crossover collisions) or the overall effect of barriers on crash severity. The objective of this study was to study the probabilities of various types of crash events possible under various road and barrier scenarios. The estimated probabilities are conditional given that at least one vehicle left the travelled way and the resulted crash had been recorded. The results are meant to deliver a useful insight onto the conversion of crashes by barriers from more to less risky to help better understand the mechanism of crash severity reduction. Such knowledge should allow engineers more accurate estimation of barriers' benefits and help researchers evaluate barriers' performance to improve the barrier's design. Seven barrier-relevant crash events possible after a vehicle departs the road could be identified based on the existing crash data and their probabilities estimated given the presence and location of three types of barriers: median concrete barriers, median and roadside W-beam steel guardrails, and high-tension median cable barriers. A multinomial logit model with variable outcomes was estimated based on 2049 barrier-relevant crashes occurred between 2003 and 2012 on 1258 unidirectional travelled ways in Indiana. The developed model allows calculating the changes in the probabilities of the barrier-relevant crash events. The results of this study indicated that road departures lead to less frequent crossings of unprotected (no barriers) medians

  10. Safety barriers for motorways : shoulder and bridge safety barriers and impact attenuators surveyed and assessed.

    NARCIS (Netherlands)

    Schoon, C.C. Heijer, T. Pol, W.H.M. van de & Jordaan, D.J.R.

    1986-01-01

    The various types and practical qualities of deformable and non-deformable safety barriers are listed. The main conclusions drawn from tests based on several safety criteria are : various types of deformable barriers (steel guide rails) perform well when hit by cars; various types of deformable barr

  11. Temperature dependent electrical characteristics of Pt Schottky barriers fabricated on lightly and highly doped n-type 4H-SiC

    Science.gov (United States)

    Huang, Lingqin; Wang, Dejun

    2015-11-01

    The temperature dependent electronic characteristics of Pt Schottky barriers fabricated on lightly and relatively highly doped n-type 4H-SiC (1 × 1016 and 1 × 1018 cm-3) are comparatively investigated. It is found that the abnormal temperature dependence of barrier height and ideality factor estimated from the thermionic emission (TE) model for both lightly and highly doped samples could be successfully explained in terms of Gaussian distribution of inhomogeneous barrier heights. However, the estimated mean barrier height according to Gaussian distribution for the highly doped sample is much lower than the actual mean value from the capacitance-voltage (C-V) measurements. Interestingly, the values of barrier height from the thermionic field emission (TFE) model are found to be close to those from the C-V measurements, indicating that the TFE model is more appropriate to explain the electrical transport for the highly doped sample.

  12. Vertical barriers with increased sorption capacities

    Energy Technology Data Exchange (ETDEWEB)

    Bradl, H.B. [Bilfinger + Berger Bauaktiengesellschaft, Mannheim (Germany)

    1997-12-31

    Vertical barriers are commonly used for the containment of contaminated areas. Due to the very small permeability of the barrier material which is usually in the order of magnitude of 10-10 m/s or less the advective contaminant transport can be more or less neglected. Nevertheless, there will always be a diffusive contaminant transport through the barrier which is caused by the concentration gradient. Investigations have been made to increase the sorption capacity of the barrier material by adding substances such as organoclays, zeolites, inorganic oxides and fly ashes. The contaminants taken into account where heavy metals (Pb) and for organic contaminants Toluole and Phenantrene. The paper presents results of model calculations and experiments. As a result, barrier materials can be designed {open_quotes}tailor-made{close_quotes} depending on the individual contaminant range of each site (e.g. landfills, gasworks etc.). The parameters relevant for construction such as rheological properties, compressive strength and permeability are not affected by the addition of the sorbents.

  13. New technologies for subsurface barrier wall construction

    Energy Technology Data Exchange (ETDEWEB)

    Mutch, R.D. Jr.; Ash, R.E. IV; Caputi, J.R. [Eckenfelder Inc., Mahwah, NJ (United States)

    1996-12-31

    New technologies for subsurface barrier wall construction are entering the marketplace at an unprecedented pace. Much of this innovation centers around construction of geomembrane barrier walls but also includes advancements in self-hardening slurries and in permeation grouts, involving such diverse materials as colloidal silica gel and montan wax emulsions. These advancements come at a time when subsurface barrier walls are cautiously emerging out of the technological closet. During much of the 1980s, barrier walls of any type were regarded in some quarters as crude and antiquated. It was correspondingly predicted that remediation would be dominated by emerging treatment technologies such as bioremediation, air sparging, and surfactant flushing. Notwithstanding the considerable successes of these emerging technologies, particularly bioremediation, the fact remains that a significant percentage of Superfund, RCRA-corrective action and other waste disposal sites present hydrogeologic, chemical, and waste matrix complexities that far exceed the capabilities of current treatment-based remedial technologies. Consequently, containment-based technologies such as subsurface barrier walls and caps are being recognized once again as irreplaceable components of practical remediation programs at many complex sites.

  14. Near-Surface Engineered Environmental Barrier Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Piet, Steven James; Breckenridge, Robert Paul; Beller, John Michael; Geesey, Gill Gregroy; Glenn, David Frankie; Jacobson, Jacob Jordan; Martian, Pete; Matthern, Gretchen Elise; Mattson, Earl Douglas; Porro, Indrek; Southworth, Finis Hio; Steffler, Eric Darwin; Stormberg, Angelica Isabel; Stormberg, Gregory John; Versteeg, Roelof Jan; White, Gregory J

    2002-08-01

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R&D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combines selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo- transpiration, capillary, and grout-based barriers will be examined.

  15. Near-Surface Engineered Environmental Barrier Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Piet, S.J.; Breckenridge, R.P.

    2002-05-15

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined.

  16. Reduced barrier efficiency in axillary stratum corneum.

    Science.gov (United States)

    Watkinson, A; Lee, R S; Moore, A E; Pudney, P D A; Paterson, S E; Rawlings, A V

    2002-06-01

    The skin of the axilla is cosmetically important with millions of consumers daily applying antiperspirant/deodorant products. Despite this, we know virtually nothing about axillary skin or how antiperspirant (AP) use impacts upon it. To characterize the axillary stratum corneum and determine whether this is a unique skin type, we have looked at stratum corneum composition and function, particularly its barrier properties, and compared it with other body sites. Transepidermal water loss (TEWL) and corneosurfametry (CSM) revealed a reduced barrier function in the axilla. HPTLC analysis of the stratum corneum lipids demonstrated statistically elevated levels of fatty acids, ceramides, and particularly cholesterol in the axilla. Both ceramide and cholesterol did not appear to change with depth, indicating that they were predominantly of stratum corneum origin. On the other hand, at least some of the fatty acid had a sebaceous origin. We hypothesized that the reduced barrier function might be owing to the changes in the crucial ceramide : cholesterol ratio. To address this, we used a combination of attenuated total reflectance-Fourier-transformed infrared spectroscopy (ATR-FTIR) with cyanoacrylate sampling. These results demonstrated more ordered lipid-lamellae phase behaviour in the axilla, suggesting that the elevated cholesterol might form crystal microdomains within the lipid lamellae, allowing an increase in water flux. Since an exaggerated application of antiperspirant had no effect upon the axilla barrier properties, it is concluded that this region of skin physiologically has a reduced barrier function.

  17. Fuel distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tison, R.R.; Baker, N.R.; Blazek, C.F.

    1979-07-01

    Distribution of fuel is considered from a supply point to the secondary conversion sites and ultimate end users. All distribution is intracity with the maximum distance between the supply point and end-use site generally considered to be 15 mi. The fuels discussed are: coal or coal-like solids, methanol, No. 2 fuel oil, No. 6 fuel oil, high-Btu gas, medium-Btu gas, and low-Btu gas. Although the fuel state, i.e., gas, liquid, etc., can have a major impact on the distribution system, the source of these fuels (e.g., naturally-occurring or coal-derived) does not. Single-source, single-termination point and single-source, multi-termination point systems for liquid, gaseous, and solid fuel distribution are considered. Transport modes and the fuels associated with each mode are: by truck - coal, methanol, No. 2 fuel oil, and No. 6 fuel oil; and by pipeline - coal, methane, No. 2 fuel oil, No. 6 oil, high-Btu gas, medium-Btu gas, and low-Btu gas. Data provided for each distribution system include component makeup and initial costs.

  18. Energy barriers, entropy barriers, and non-Arrhenius behavior in a minimal glassy model.

    Science.gov (United States)

    Du, Xin; Weeks, Eric R

    2016-06-01

    We study glassy dynamics using a simulation of three soft Brownian particles confined to a two-dimensional circular region. If the circular region is large, the disks freely rearrange, but rearrangements are rarer for smaller system sizes. We directly measure a one-dimensional free-energy landscape characterizing the dynamics. This landscape has two local minima corresponding to the two distinct disk configurations, separated by a free-energy barrier that governs the rearrangement rate. We study several different interaction potentials and demonstrate that the free-energy barrier is composed of a potential-energy barrier and an entropic barrier. The heights of both of these barriers depend on temperature and system size, demonstrating how non-Arrhenius behavior can arise close to the glass transition.

  19. The Rashba effect on a double-barrier spin polarizer

    Science.gov (United States)

    Makler, Sergio S.; Guilherme Zelcovit, João; Boselli, Marco A.; da Cunha Lima, Ivan C.

    2004-12-01

    The Rashba effect on a double-barrier spin polarizer is considered using a formalism that produces accurate results with little computational effort. In previous articles, we proposed a spin polarizer consisting of a well made of a dilute magnetic semiconductor (DMS) enclosed by two non-magnetic barriers. In the absence of Rashba effect, the magnetization of the well produces totally polarized electronic levels separated by 0.15 eV. The highest steady magnetic field obtained in a laboratory could not produce a Zeeman splitting so big. As a consequence the calculated currents are almost totally polarized. The Rashba spin-orbit Hamiltonian produces a spin flip. Therefore, the levels at the well have not well-defined spin polarization and the currents are less polarized. The device presented here would be useful for spintronics because there are DMS ferromagnetic at room temperature. Our tight-binding Hamiltonian, including the Rashba term, is H=HK+HP+HE+HM+H+H+HR . The first term is the kinetic energy. HP describes the double-barrier profile and the third term represent the electric field due to the applied bias. The magnetic HM, the hole-impurity H and the hole-hole H terms are included in the mean field approximation. The profile and the charge distribution are calculated self-consistently. By using a decimation formalism, all these terms are treated exactly. Finally, the Rashba term HR is very small. Therefore, it is treated using second order perturbation theory. The calculation confirm that the Rashba effect on the currents is of second order. Consequently, the resulting depolarization is very small.

  20. The Rashba effect on a double-barrier spin polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Makler, Sergio S. [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, 24210-340 Niteroi-RJ (Brazil)]. E-mail: sergio@if.uff.br; Guilherme Zelcovit, Joao [Instituto de Fisica, Universidade do Estado de Rio de Janeiro, RJ (Brazil); Boselli, Marco A. [Departamento de Fisica, Universidade Federal de Ouro Preto, MG (Brazil); Cunha Lima, Ivan C. da [Instituto de Fisica, Universidade do Estado de Rio de Janeiro, RJ (Brazil)

    2004-12-31

    The Rashba effect on a double-barrier spin polarizer is considered using a formalism that produces accurate results with little computational effort. In previous articles, we proposed a spin polarizer consisting of a well made of a dilute magnetic semiconductor (DMS) enclosed by two non-magnetic barriers. In the absence of Rashba effect, the magnetization of the well produces totally polarized electronic levels separated by 0.15eV. The highest steady magnetic field obtained in a laboratory could not produce a Zeeman splitting so big. As a consequence the calculated currents are almost totally polarized. The Rashba spin-orbit Hamiltonian produces a spin flip. Therefore, the levels at the well have not well-defined spin polarization and the currents are less polarized. The device presented here would be useful for spintronics because there are DMS ferromagnetic at room temperature. Our tight-binding Hamiltonian, including the Rashba term, isH=HK+HP+HE+HM+Hh-i+Hh-h+HR.The first term is the kinetic energy. HP describes the double-barrier profile and the third term represent the electric field due to the applied bias. The magnetic HM, the hole-impurity Hh-i and the hole-hole Hh-h terms are included in the mean field approximation. The profile and the charge distribution are calculated self-consistently.By using a decimation formalism, all these terms are treated exactly. Finally, the Rashba term HR is very small. Therefore, it is treated using second order perturbation theory. The calculation confirm that the Rashba effect on the currents is of second order. Consequently, the resulting depolarization is very small.

  1. Damage Distributions

    DEFF Research Database (Denmark)

    Lützen, Marie

    2001-01-01

    the damage location, the damage sizes and the main particulars of the struck vessel. From the numerical simulation and the analyse of the damage statistics it is found that the current formulation from the IMO SLF 43/3/2 can be used as basis for determination of the p-, r-, and v-factors. Expressions...... and methods of calculation have been discussed. The damage distributions for the different vessels have been compared and analyses regarding relations between damage parameters and main particulars have been performed. The damage statistics collected in work package 1 have been analysed for relations between...... for the distribution of the non-dimensional damage location, the non-dimensional damage length and the non-dimensional penetrations have been derived. These distributions have been used as basis for a proposal for the p- and r-factors. Two proposals for the v-factor have been performed using the damage statistics...

  2. Distributed creativity

    DEFF Research Database (Denmark)

    Glaveanu, Vlad Petre

    used within the literature and yet it has the potential to revolutionise the way we think about creativity, from how we define and measure it to what we can practically do to foster and develop creativity. Drawing on cultural psychology, ecological psychology and advances in cognitive science......This book challenges the standard view that creativity comes only from within an individual by arguing that creativity also exists ‘outside’ of the mind or more precisely, that the human mind extends through the means of action into the world. The notion of ‘distributed creativity’ is not commonly......, this book offers a basic framework for the study of distributed creativity that considers three main dimensions of creative work: sociality, materiality and temporality. Starting from the premise that creativity is distributed between people, between people and objects and across time, the book reviews...

  3. 渤海湾西岸的几道贝壳堤%A Few of Barrier Sand-bars on the West Coast of Bohai Bay

    Institute of Scientific and Technical Information of China (English)

    岳军; Dongyue; 张宝华; 耿秀山; 刘雪松; 赵希涛; 牟林; 张百鸣; 韩芳

    2012-01-01

    There are 6 Barrier Sand-bars are outcropped or buried on the west coast of Bohai Bay. Based on the geological survey, it is found that the plane distribution features texture of the Barrier Sand-bars, which are from the old to the new are roughly parallel with the coast along the west coast of Bohai Bay (from the coast to the sea). The distribution of the Barrier Sand-bars can be divided into two kinds, one is from the new to the old, and the other one is from the old to the new. In this paper, the division of the Barrier Sand-bars from I (old) to VI (new) by using the latter one. Through the description of the material composition and the accumulation characteristics to each barrier sand-bar (figure. 2 to figure. 7) , conducting the mathematical statistics for the geometrical morphological features (table 2), comparing analysis the formation age features and the division scheme (table 3), summing up the biological assemblages (table 1), the result reveal the occurrence, formation age and the tidal level change of the Barrier Sand-bars from I to VI (figure. 8). In the basis of the Barrier Sand-bars as a particular geological carrier, the author try to analysis and reveal the genetic mechanism in a macroscopic view, and consider that the generalized Bohai Sea is inland semi-lagoon or local sea in reality, (table. 4 figure. 9) Shangdong Miaodao Island and Liaodong Peninsula constitute barrier coast for Bohai Sea. After comparing analysis to massive data, the barrier coast is an only essential condition to form kebohe delta and beaked delta, both of which may be a possibility condition to form barrier bars (barrier island, barrier beach) or shell ridges. This result is just main genetic mechanism for the shell ridges.

  4. Distributed Logics

    Science.gov (United States)

    2014-10-03

    that must be woven into proofs of security statements. 03-10-2014 Memorandum Report Logic System-on-a-Chip Distributed systems 9888 ASDR&EAssistant...can be removed without damaging the logic. For all propositional letters p, E1. p ⊃ [r] p From now on, a distributed logic contains at least the...a ∈ x iff 〈h〉 ∈ x. These same definitions work for the canonical relation R for r : h y k where now a ∈ MA(k), [r] a, 〈r〉 a ∈ MA(h), x ∈ CF(h), and

  5. Reconciling transition path time and rate measurements in reactions with large entropic barriers

    Science.gov (United States)

    Makarov, Dmitrii E.

    2017-02-01

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  6. Intrinsic inhomogeneity in barrier height at monolayer graphene/SiC Schottky junction

    Science.gov (United States)

    Tomer, D.; Rajput, S.; Hudy, L. J.; Li, C. H.; Li, L.

    2014-07-01

    Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties. The inherent spatial inhomogeneity due to the formation of ripples and ridges in graphene can lead to fluctuations in the Schottky barrier height (SBH). The non-ideal behavior of the temperature dependent barrier height and ideality factor greater than 4 can be attributed to these spatial inhomogeneities. Assuming a Gaussian distribution of the barrier, mean SBHs of 1.30 ± 0.18 eV and 1.16 ± 0.16 eV are found for graphene/SiC junctions on the C- and Si-face, respectively. These findings reveal intrinsic spatial inhomogeneities in the SBHs in graphene based Schottky junctions.

  7. Relative motion correction to fission barriers

    CERN Document Server

    Skalski, J

    2007-01-01

    We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy6 show that the correction, previously estimated as $\\sim$ 8 MeV in $A=70-100$ nuclei, amounts to 4 MeV in the medium heavy nucleus $^{198}$Hg and to null in $^{238}$U. However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

  8. Relative Motion Correction to Fission Barriers

    Science.gov (United States)

    Skalski, J.

    We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy6 show that the correction, previously estimated as ~ 8 MeV in A = 70 - 100 nuclei, amounts to 4 MeV in the medium heavy nucleus 198Hg and to null in 238U. However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

  9. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: arriaga@ifuap.buap.mx [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)

    2015-04-15

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  10. Constructing bottom barriers with met grouting

    Energy Technology Data Exchange (ETDEWEB)

    Shibazaki, M.; Yoshida, H. [Chemical Grouting Company, Tokyo (Japan)

    1997-12-31

    Installing a bottom barrier using conventional high pressure jetting technology and ensuring barrier continuity is challenging. This paper describes technology that has been developed and demonstrated for the emplacement of bottom barriers using pressures and flow rates above the conventional high pressure jetting parameters. The innovation capable of creating an improved body exceeding 5 meters in diameter has resulted in the satisfying connection and adherence between the treated columns. Besides, the interfaces among the improved bodies obtain the same strength and permeability lower than 1 x 10{sup -7} cm/sec as body itself. A wide variety of the thickness and the diameter of the improved mass optimizes the application, and the method is nearing completion. The paper explains an aspect and briefs case histories.

  11. Compositional Safety Analysis using Barrier Certificates

    DEFF Research Database (Denmark)

    Sloth, Christoffer; Pappas, George J.; Wisniewski, Rafael

    2012-01-01

    This paper proposes a compositional method for verifying the safety of a dynamical system, given as an interconnection of subsystems. The safety verification is conducted by the use of the barrier certificate method; hence, the contribution of this paper is to show how to obtain compositional...... conditions for safety verification. We show how to formulate the verification problem, as a composition of coupled subproblems, each given for one subsystem. Furthermore, we show how to find the compositional barrier certificates via linear and sum of squares programming problems. The proposed method makes...... it possible to verify the safety of higher dimensional systems, than the method for centrally computed barrier certificates. This is demonstrated by verifying the safety of an emergency shutdown of a wind turbine....

  12. On the Existence of Compositional Barrier Certificates

    DEFF Research Database (Denmark)

    Sloth, Christoffer; Wisniewski, Rafael; Pappas, George J.

    2012-01-01

    This paper provides a necessary and sufficient condition for the compositional verification of a continuous system with additively separable barrier functions. The compositional safety verification enables the verification of an interconnection of subsystems. The idea behind the compositional...... analysis is to allow the verification of systems with a high dimension, by the verification of multiple lower dimensional subproblems. In the compositional safety analysis, a particular structure is imposed on the barrier certificate, restricting the applicability of the method. We show an example...... for the compositional safety analysis that enables the verification of the counterexample, by imposing a less restrictive structure of the barrier function. This shows that the counterexample can be solved with a compositional method, but at an increased computational complexity....

  13. Barriers faced by Romanian SMEs in exporting

    Directory of Open Access Journals (Sweden)

    Dana BOŞCOR

    2017-07-01

    Full Text Available This study aims to identify the most important barriers faced by Romanians SMEs in the process of exporting. The research was based on a focus group including 12 managers from different exporting companies from Brasov. The most important barriers encountered by companies were linked to currency fluctuations, methods of payment, lack of specialized staff, lack of financial resources and a low level of government support. Results from the study revealed that companies should have access at financing in order to invest in new technologies and to create higher quality products that could meet the requirements of the foreign buyers. In order to reduce the export barriers, small and medium sized exporters should create partnerships for reducing the costs of promotion in foreign markets. The government should also increase its support by offering exporters access at financing and market information at lower costs.

  14. Epidermal Growth Factor and Intestinal Barrier Function

    Directory of Open Access Journals (Sweden)

    Xiaopeng Tang

    2016-01-01

    Full Text Available Epidermal growth factor (EGF is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

  15. Stratum corneum barrier integrity controls skin homeostasis.

    Science.gov (United States)

    Smith, W

    1999-04-01

    The stratum corneum water barrier controls structural and functional properties of both the epidermis and the dermis. Treatments which chronically disrupt the stratum corneum water barrier can induce changes similar to those seen with 'anti-aging' treatments such as (-Hydroxy acids (AHAs) and Retin Atrade mark. Barrier disruption via daily tape stripping increases epidermal and dermal thickness, superficial and integral skin firmness, and improves skin surface texture. Modest or transitory disruption did not produce such effects. Similar results were observed with topical application of AHAs, retinoids or mild irritants after about 4-6 weeks provided such treatments resulted in prolonged elevation in TEWL (trans-epidermal water loss). Treatments that did not chronically elevate TEWL could also produce positive cosmetic effects, but such effects were in general restricted to the skin surface or epidermis. Irritation, which was observed with some treatments, was not solely responsible for the positive effects observed.

  16. Quantum walk search through potential barriers

    Science.gov (United States)

    Wong, Thomas G.

    2016-12-01

    An ideal quantum walk transitions from one vertex to another with perfect fidelity, but in physical systems, the particle may be hindered by potential energy barriers. Then the particle has some amplitude of tunneling through the barriers, and some amplitude of staying put. We investigate the algorithmic consequence of such barriers for the quantum walk formulation of Grover’s algorithm. We prove that the failure amplitude must scale as O(1/\\sqrt{N}) for search to retain its quantum O(\\sqrt{N}) runtime; otherwise, it searches in classical O(N) time. Thus searching larger ‘databases’ requires increasingly reliable hop operations or error correction. This condition holds for both discrete- and continuous-time quantum walks.

  17. Barriers to evidence-based medicine: a systematic review.

    Science.gov (United States)

    Sadeghi-Bazargani, Homayoun; Tabrizi, Jafar Sadegh; Azami-Aghdash, Saber

    2014-12-01

    Evidence-based medicine (EBM) has emerged as an effective strategy to improve health care quality. The aim of this study was to systematically review and carry out an analysis on the barriers to EBM. Different database searching methods and also manual search were employed in this study using the search words ('evidence-based' or 'evidence-based medicine' or 'evidence-based practice' or 'evidence-based guidelines' or 'research utilization') and (barrier* or challenge or hinder) in the following databases: PubMed, Scopus, Web of Knowledge, Cochrane library, Pro Quest, Magiran, SID. Out of 2592 articles, 106 articles were finally identified for study. Research barriers, lack of resources, lack of time, inadequate skills, and inadequate access, lack of knowledge and financial barriers were found to be the most common barriers to EBM. Examples of these barriers were found in primary care, hospital/specialist care, rehabilitation care, medical education, management and decision making. The most common barriers to research utilization were research barriers, cooperation barriers and changing barriers. Lack of resources was the most common barrier to implementation of guidelines. The result of this study shows that there are many barriers to the implementation and use of EBM. Identifying barriers is just the first step to removing barriers to the use of EBM. Extra resources will be needed if these barriers are to be tackled. © 2014 John Wiley & Sons, Ltd.

  18. Model-Free Optimal Control of Distributed Energy Resources in Electric Power Distribution Systems

    OpenAIRE

    Arnold, Daniel Brian

    2015-01-01

    Distributed Energy Resources (DER) have the potential to both improve the manner in which the electric power distribution system is operated and provide services to the bulk electric grid. A key question that has emerged in academic circles is the manner in which DER is governed to provide such utility. While many of the suggested approaches are mathematically elegant and demonstrate positive performance in simulations, they face enormous barriers to implementation due to their reliance on ...

  19. Surface barrier research at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Gee, G.W.; Ward, A.L.; Fayer, M.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-12-31

    At the DOE Hanford Site, a field-scale prototype surface barrier was constructed in 1994 over an existing waste site as a part of a CERCLA treatability test. The above-grade barrier consists of a fine-soil layer overlying coarse layers of sands, gravels, basalt rock (riprap), and a low permeability asphalt layer. Two sideslope configurations, clean-fill gravel on a 10:1 slope and basalt riprap on a 2:1 slope, were built and are being tested. Design considerations included: constructability; drainage and water balance monitoring, wind and water erosion control and monitoring; surface revegetation and biotic intrusion; subsidence and sideslope stability, and durability of the asphalt layer. The barrier is currently in the final year of a three-year test designed to answer specific questions related to stability and long-term performance. One half of the barrier is irrigated such that the total water applied, including precipitation, is 480 mm/yr (three times the long-term annual average). Each year for the past two years, an extreme precipitation event (71 mm in 8 hr) representing a 1,000-yr return storm was applied in late March, when soil water storage was at a maximum. While the protective sideslopes have drained significant amounts of water, the soil cover (2-m of silt-loam soil overlying coarse sand and rock) has never drained. During the past year there was no measurable surface runoff or wind erosion. This is attributed to extensive revegetation of the surface. In addition, the barrier elevation has shown a small increase of 2 to 3 cm that is attributed to a combination of root proliferation and freeze/thaw activity. Testing will continue through September 1997. Performance data from the prototype barrier will be used by DOE in site-closure decisions at Hanford.

  20. Translating microfluidics: Cell separation technologies and their barriers to commercialization.

    Science.gov (United States)

    Shields, C Wyatt; Ohiri, Korine A; Szott, Luisa M; López, Gabriel P

    2017-03-01

    Advances in microfluidic cell sorting have revolutionized the ways in which cell-containing fluids are processed, now providing performances comparable to, or exceeding, traditional systems, but in a vastly miniaturized format. These technologies exploit a wide variety of physical phenomena to manipulate cells and fluid flow, such as magnetic traps, sound waves and flow-altering micropatterns, and they can evaluate single cells by immobilizing them onto surfaces for chemotherapeutic assessment, encapsulate cells into picoliter droplets for toxicity screenings and examine the interactions between pairs of cells in response to new, experimental drugs. However, despite the massive surge of innovation in these high-performance lab-on-a-chip devices, few have undergone successful commercialization, and no device has been translated to a widely distributed clinical commodity to date. Persistent challenges such as an increasingly saturated patent landscape as well as complex user interfaces are among several factors that may contribute to their slowed progress. In this article, we identify several of the leading microfluidic technologies for sorting cells that are poised for clinical translation; we examine the principal barriers preventing their routine clinical use; finally, we provide a prospectus to elucidate the key criteria that must be met to overcome those barriers. Once established, these tools may soon transform how clinical labs study various ailments and diseases by separating cells for downstream sequencing and enabling other forms of advanced cellular or sub-cellular analysis. © 2016 International Clinical Cytometry Society. © 2016 International Clinical Cytometry Society.