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Sample records for breakup reactions

  1. Progress in all-order breakup reaction theories

    Indian Academy of Sciences (India)

    Progress in breakup reaction theories, like the distorted wave Born approximation, the continuum discretized coupled channels method and the dynamical eikonal approximation, is brought into focus. The need to calculate exclusive reaction observables and the utility of benchmark tests as arbitrators of theoretical models ...

  2. Progress in all-order breakup reaction theories

    Indian Academy of Sciences (India)

    Breakup reactions are one of the most sought-after methods to study the structure of nuclei right from stable to those near the drip lines. For the latter case it is perhaps the only technique which is reasonably successful in dealing with exotic species – like halo nuclei. It is thus challenging to construct a theoretical model.

  3. Break-up reactions: theoretical aspects; Reactions de dissociation: aspects theoriques

    Energy Technology Data Exchange (ETDEWEB)

    Baye, D. [Universite Libre de Bruxelles (ULB), Physique Quantique, C.P. 165/82, Physique Nucleaire Theorique et Physique Mathematique, Brussels (Belgium)

    2007-07-01

    Breakup reactions are one of the main tools for the study of exotic nuclei. In particular, Coulomb breakup is expected to provide information on spectroscopic properties of halo nuclei and on astrophysical S factors for radiative-capture reactions. The simplest studies are based on perturbation theory and especially on its first order. However the validity of the first-order approximation may be limited for extended systems such as halo nuclei and its conditions are not always satisfied in existing experiments. More elaborate reaction models are available: resolution of the semi-classical time-dependent Schroedinger equation, eikonal and dynamical eikonal approximations, method of coupled discretized-continuum channels (CDCC). These methods are reviewed and summarized. Their interest and limitations are discussed. The Be{sup 11} and B{sup 8} breakups are treated as examples of the various approximations. (author)

  4. Experimental and simulated d p breakup reaction data at 300, 400 and 500 MeV

    Directory of Open Access Journals (Sweden)

    Janek M.

    2014-01-01

    Full Text Available d p breakup reaction occupies large phase space. Two and three nucleon forces and relativistic effects can be investigated under various detector configuration. The results of simulation of d p breakup reaction in energy region from 300 to 500 MeV are presented. Preliminary results obtained at 300, 400 and 500 MeV of deuteron energy at some detector configurations at Nuclotron as well as future plans in investigation of relativistic effects are discussed.

  5. Approximations in fusion and breakup reactions induced by radioactive beams

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, W.H.Z.; Carlin Filho, N.; Hussein, M.S. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Canto, L.F.; Donangelo, R. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Lubian, J. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica; Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Romanelli, A. [Facultad de Ingenieria, Montevideo (Uruguay). Inst. de Fisica

    2000-07-01

    Some commonly used approximations for complete fusion and breakup transmission coefficients in collisions of weakly bound projectiles at near barrier energies are assessed. We show that they strongly depend on the adopted classical trajectory and can be significantly improved with proper treatment of the incident and emergent currents in the WKB approximation. (author)

  6. Measurements of scattering observables for the pd break-up reaction

    Directory of Open Access Journals (Sweden)

    Stephan E.

    2010-04-01

    Full Text Available High-precision measurements of the scattering observables such as cross sections and analyzing powers for the proton-deuteron elastic and break-up reactions have been performed at KVI in the last two decades and elsewhere to investigate various aspects of the three-nucleon force (3NF effects simultaneously. In 2006 an experiment was performed to study these effects in p+d break-up reaction at 135 MeV with the detection system, Big Instrument for Nuclear polarization Analysis, BINA. BINA covers almost the entire kinematical phase space of the break-up reaction. The results are interpreted with the help of state-of-the-art Faddeev calculations and are partly presented in this contribution.

  7. Transfer and breakup reactions in 16O + CsI at 16.4 MeV/n

    Directory of Open Access Journals (Sweden)

    M.J. Murphy

    1983-01-01

    Full Text Available A streamer-chamber particle-telescope system has been used to observe ejectile charge, energy, and associated charged particle multiplicity in the reaction of 16O + CsI at 16.4 MeV/n. The measurement provides relative probabilities for transfer and projectile breakup as a function of ejectile charge, and spectra for the heavy ejectiles from transfer and breakup events. The results show that the interaction energy of 16.4 MeV/n is near the threshold for breakup reactions in heavy-ion collisions.

  8. Influence of breakup on elastic and α-production channels in the 6Li+ 116Sn reaction

    Science.gov (United States)

    Patel, D.; Mukherjee, S.; Deshmukh, N.; Lubian, J.; Wang, Jian-Song; Correa, T.; Nayak, B. K.; Yang, Yan-Yun; Ma, Wei-Hu; Biswas, D. C.; Gupta, Y. K.; Santra, S.; Mirgule, E. T.; Danu, L. S.; Singh, N. L.; Saxena, A.

    2017-10-01

    The effects of breakup reactions on elastic and α-production channels for the 6Li+116Sn system have been investigated at energies below and near the Coulomb barrier. The angular distributions of α-particle production differential cross sections have been obtained at several projectile energies between 22 and 40 MeV. The measured breakup α-particle differential cross sections and elastic scattering angular distributions have been compared with the predictions of continuum-discretized coupled channels (CDCC) calculations. The influence of breakup coupling has also been investigated by extracting dynamic polarization potentials (DPP) from the CDCC calculations. From the predictions of CDCC calculations the relative importance of the nuclear, Coulomb, and total breakup contributions have also been investigated. The nuclear breakup couplings are observed to play an important role in comparison to the Coulomb breakup for the direct breakup mechanisms associated in the reaction of 6Li projectile with 116Sn target nuclei. The influence of strong nuclear breakup coupling exhibits suppression in the Coulomb-nuclear interference peak. The direct breakup cross sections from the CDCC calculations under-predict the measured α-particle differential cross sections at all energies. This suggests that the measured α particles may also have contributions from other possible breakup reaction channels. One of the authors (SM) would like to thank DAE-BRNS for financial assistance through a major research project. This work is supported by National Natural Science Foundation of China (U1432247, 11575256, U1632138, 11605253) and China Postdoctoral Science Foundation (2016M602906)

  9. Study of {sup 19}C by breakup reactions; Etude du {sup 19}C par reactions de cassure

    Energy Technology Data Exchange (ETDEWEB)

    Liegard, Emmanuel [Lab. de Physique Corpusculaire, Caen Univ., 14 Caen (France)

    1998-01-07

    To date studies of halo nuclei have been principally focussed on the A 11 systems {sup 11}Li and {sup 11}Be. The evolution of the properties of the halo with the mass of the system and the binding energy and angular momentum of the halo nucleons is a question of fundamental importance. It was in this spirit that the present study of {sup 19}C (S{sub n} = 240 {+-} 100 keV) was undertaken. The experiment was performed at GANIL using a secondary {sup 19}C beam ({approx_equal} 15 pps at 36 MeV/nucleon) produced via fragmentation. The experimental setup which included the neutron array DEMON, provided for identification of the core-breakup and dissociation reaction channels. In the first case, a very narrow single neutron angular distribution (FWHM = 64 {+-} 17 MeV/c) was observed for {sup 19}C, in contrast to that found for three `reference` nuclei {sup 21}N, {sup 22}O and {sup 24}F (FWHM {approx_equal} 165 MeV/c). This result could be interpreted within the framework of the core-breakup reaction model of a one-neutron halo nucleus. The results obtained for dissociation, while supporting the existence of the halo, indicated that it is not well developed. In addition, a comparison between the present results, the parallel momentum distributions for the core ({sup 18}C) and theoretical predictions have allowed conclusions to be drawn regarding the configuration of the valence neutron. In particular, a purely 2s{sub 1/2} of 1d{sub 5/2} configuration is excluded and mixing, possible with core excited states, must be considered. A probable ground state spin-parity assignment of 3{sup +}/2 or 5{sup +}/2 is suggested. (author) 150 refs., 278 figs., 28 tabs.

  10. Drift and breakup of spiral waves in reaction-diffusion-mechanics systems.

    Science.gov (United States)

    Panfilov, A V; Keldermann, R H; Nash, M P

    2007-05-08

    Rotating spiral waves organize excitation in various biological, physical, and chemical systems. They underpin a variety of important phenomena, such as cardiac arrhythmias, morphogenesis processes, and spatial patterns in chemical reactions. Important insights into spiral wave dynamics have been obtained from theoretical studies of the reaction-diffusion (RD) partial differential equations. However, most of these studies have ignored the fact that spiral wave rotation is often accompanied by substantial deformations of the medium. Here, we show that joint consideration of the RD equations with the equations of continuum mechanics for tissue deformations (RD-mechanics systems), yield important effects on spiral wave dynamics. We show that deformation can induce the breakup of spiral waves into complex spatiotemporal patterns. We also show that mechanics leads to spiral wave drift throughout the medium approaching dynamical attractors, which are determined by the parameters of the model and the size of the medium. We study mechanisms of these effects and discuss their applicability to the theory of cardiac arrhythmias. Overall, we demonstrate the importance of RD-mechanics systems for mathematics applied to life sciences.

  11. Study of breakup and transfer of weakly bound nucleus 6Li to explore the low energy reaction dynamics

    Science.gov (United States)

    Zhang, G. L.; Zhang, G. X.; Hu, S. P.; Zhang, H. Q.; Gomes, P. R. S.; Lubian, J.; Guo, C. L.; Wu, X. G.; Yang, J. C.; Zheng, Y.; Li, C. B.; He, C. Y.; Zhong, J.; Li, G. S.; Yao, Y. J.; Guo, M. F.; Sun, H. B.; Valiente-Dobòn, J. J.; Goasduff, A.; Siciliano, M.; Galtarosa, F.; Francesco, R.; Testov, D.; Mengoni, D.; Bazzacco, D.; John, P. R.; Qu, W. W.; Wang, F.; Zheng, L.; Yu, L.; Chen, Q. M.; Luo, P. W.; Li, H. W.; Wu, Y. H.; Zhou, W. K.; Zhu, B. J.; Li, E. T.; Hao, X.

    2017-11-01

    Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. However, owing to the low intensities of the presently available radioactive ion beam (RIB), it is difficult to clearly explore the reaction mechanisms of nuclear systems with unstable nuclei. In comparison with RIB, the beam intensities of stable weakly bound nuclei such as 6,7Li and 9Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements have already been performed with those stable weakly bound nuclei, and the effect of breakup of those nuclei on the fusion process has been extensively studied. Those nuclei indicated large production cross sections for particles other than the α + x breakup. The particles are originated from non-capture breakup (NCBU), incomplete fusion (ICF) and transfer processes. However, the conclusion of reaction dynamics was not clear and has the contradiction. In our previous experiments we have performed 6Li+96Zr and 154Sm at HI-13 Tandem accelerator of China Institute of Atomic Energy (CIAE) by using HPGe array. It is shown that there is a small complete fusion (CF) suppression on medium-mass target nucleus 96Zr different from about 35% suppression on heavier target nucleus 154Sm at near-barrier energies. It seems that the CF suppression factor depends on the charge of target nuclei. We also observed one neutron transfer process. However, the experimental data are scarce for medium-mass target nuclei. In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, we performed the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV on Galileo array in cooperation with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using particle-particle and particle-γ coincidences, the different reaction mechanisms can be clearly explored.

  12. Measurement of the reaction 2H(e,e') at 180 degrees close to the deuteron breakup threshold.

    Science.gov (United States)

    Ryezayeva, N; Arenhövel, H; Burda, O; Byelikov, A; Chernykh, M; Enders, J; Griesshammer, H W; Kalmykov, Y; von Neumann-Cosel, P; Ozel, B; Poltoratska, I; Pysmenetska, I; Rangacharyulu, C; Rathi, S; Richter, A; Schrieder, G; Shevchenko, A; Yevetska, O

    2008-05-02

    Inclusive inelastic electron scattering off the deuteron under 180 degrees has been studied at the S-DALINAC close to the breakup threshold at momentum transfers q=0.27 fm;{-1} and 0.74 fm;{-1} with good energy resolution sufficient to map in detail the spin flip M1 response, which governs the starting reaction pn-->dgamma of big-bang nucleosynthesis over most of the relevant temperature region. Results from potential model calculations and (for q=0.27 fm;{-1}) from pionless nuclear effective field theory are in excellent agreement with the data.

  13. New measurement of the neutron-proton scattering length anp via the n-d breakup reaction at 25 MeV

    Science.gov (United States)

    Deng, J.; Siepe, A.; von Witsch, W.

    2002-10-01

    The 1S0 n-p scattering length anp has been measured using the n-d breakup reaction at 25 MeV. The experiment was performed in a geometry where the neutron and proton were detected in coincidence at the same angle. The data were analyzed with rigorous three-nucleon calculations using realistic nucleon-nucleon potentials. The result of anp=-24.3+/-1.1 fm agrees with the well-known value from free n-p scattering, and also with previous results from n-d breakup experiments which were performed in different geometries.

  14. 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).

  15. /sup 3/He breakup reaction by 65 MeV protons in the FSI region

    Energy Technology Data Exchange (ETDEWEB)

    Okihana, A.; Takashima, R.; Fukunaga, K.; Kakigi, S.; Ohsawa, T.; Sekioka, T.; Yokota, H.

    1987-02-16

    The angular distributions of the differential cross sections and the analyzing powers for the /sup 3/He(p,p)dp and /sup 3/He(p,pd)/sup 1/H reactions have been measured in the FSI region. The multiple scattering calculation including to double scattering terms has reproduced the differential cross sections well.

  16. A tool for calculation of 7Li(p,n)7Be neutron source spectra below the three-body break-up reaction threshold

    Science.gov (United States)

    Pachuau, Rebecca; Lalremruata, B.; Otuka, N.; Hlondo, L. R.; Punte, L. R. M.; Thanga, H. H.

    2017-09-01

    We developed a new deterministic neutron source spectrum code EPEN - Energy of Proton Energy of Neutron - for a given lithium target thickness, sample angular coverage and proton energy from the reaction threshold to the three-body break-up threshold. The angular differential cross sections of the 7Li(p,n0)7Be and 7Li(p,n1)7Be reactions evaluated by Liskien and Paulsen were adopted above 1.95 MeV while the functional form suggested by Macklin and Gibbons was adopted for the 7Li(p,n0)7Be reaction cross section near threshold. The spectra obtained by EPEN are validated by the experimental spectra and also compared with the spectra predicted by two Monte Carlo codes, SimLiT and PINO. The results of comparison are discussed in detail.

  17. Breakup of proton-rich nuclei ^24Si, ^23Al, ^22Mg, ^21Na at intermediate energies for reaction rates in explosive H-burning in novae

    Science.gov (United States)

    Banu, A.; Trache, L.; Tribble, R. E.; Gagliardi, C. A.; Orr, N.; Chartier, M.; Roussel-Chomaz, P.; Carstoiu, F.; Bonaccorso, A.

    2008-10-01

    We discuss the use of one proton-removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics, with particular reference to the results of a GANIL experiment with a cocktail beam around ^23Al at 50 MeV/nucleon. Momentum distributions of the core fragments, inclusive and in coincidence with gamma rays, were measured, from which we can determine mixing ratios in the structure of the ground states of the projectile nuclei. The method has the advantage that it can be used for beams of low quality, such as cocktail beams, and intensities as low as a few pps. The breakup reactions provide complementary information to the use of transfer reactions (the ANC method) which require radioactive beams of much better purity and intensity. Results on ^23Al, ^24Si, ^22Mg and ^21Na will be discussed.

  18. Exclusive measurement of breakup reactions with the one-neutron halo nucleus sup 1 sup 1 Be

    CERN Document Server

    Palit, R; Aumann, T; Boretzky, K; Carlson, B V; Cortina-Gil, D; Elze, T W; Emling, H; Geissel, H; Hellström, M; Jones, K L; Kratz, J V; Kulessa, R; Leifels, Y; Leistenschneider, A; Münzenberg, G; Nociforo, C; Reiter, P; Simon, H; Sümmerer, K; Walús, W

    2003-01-01

    Electromagnetic and nuclear inelastic scattering of the halo nucleus sup 1 sup 1 Be have been investigated by a measurement of the one-neutron removal channel, utilizing a secondary sup 1 sup 1 Be beam with an energy of 520 MeV/nucleon impinging on lead and carbon targets. All decay products, i.e. sup 1 sup 0 Be fragments, neutrons, and gamma-rays have been detected in coincidence. Partial cross sections for the population of ground and excited states in sup 1 sup 0 Be were determined for nuclear diffractive breakup as well as for electromagnetically induced breakup. The partial cross sections for ground-state transitions have been differentiated further with respect to excitation energy, and the dipole-strength function associated solely with transitions of the halo 2s sub 1 sub / sub 2 neutron to the continuum has been derived. The extracted dipole strength integrated from the neutron threshold up to 6.1 MeV excitation energy amounts to 0.90(6) e sup 2 fm sup 2. A spectroscopic factor for the nu 2s sub 1 su...

  19. Fermi breakup and the statistical multifragmentation model

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, B.V., E-mail: brett@ita.br [Departamento de Fisica, Instituto Tecnologico de Aeronautica - CTA, 12228-900 Sao Jose dos Campos (Brazil); Donangelo, R. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CP 68528, 21941-972, Rio de Janeiro (Brazil); Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, Julio Herrera y Reissig 565, 11.300 Montevideo (Uruguay); Souza, S.R. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CP 68528, 21941-972, Rio de Janeiro (Brazil); Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, CP 15051, 91501-970, Porto Alegre (Brazil); Lynch, W.G.; Steiner, A.W.; Tsang, M.B. [Joint Institute for Nuclear Astrophysics, National Superconducting Cyclotron Laboratory and the Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2012-02-15

    We demonstrate the equivalence of a generalized Fermi breakup model, in which densities of excited states are taken into account, to the microcanonical statistical multifragmentation model used to describe the disintegration of highly excited fragments of nuclear reactions. We argue that such a model better fulfills the hypothesis of statistical equilibrium than the Fermi breakup model generally used to describe statistical disintegration of light mass nuclei.

  20. Breakup of proton-rich nuclei ^24Si and ^23Al at intermediate energies for reaction rates in explosive H-burning in novae and X-ray bursts

    Science.gov (United States)

    Banu, A.; Trache, L.; Tribble, R. E.; Roeder, B.; Simmons, E.; Orr, N.; Chartier, M.; Lemmon, R.; Catford, W.; Freer, M.; Carstoiu, F.; Horoi, M.; Bonaccorso, A.; et al.

    2009-10-01

    We present the use of one-proton-removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics, with particular reference to the results of a GANIL experiment with a cocktail beam around ^23Al at 50 MeV/nucleon. Momentum distributions of the core fragments, inclusive and in coincidence with gamma rays, from which we determine configuration mixing in the structure of the ground states of the projectile nuclei, were measured. The method has the advantage that it can be used for beams of low quality, such as cocktail beams, and intensities as low as a few pps. These breakup reactions provide information on H-burning reaction rates for ^22Mg(p,γ)^23Al and ^23Al(p,γ)^24Si, important in novae and X-ray bursts.

  1. Influence of projectile breakup on complete fusion

    Indian Academy of Sciences (India)

    illustrates the typical reaction mechanisms following the breakup of weakly bound projectiles. When whole of the projectile fuses with whole of the target, the process is known as direct complete fusion (DCF). If prior to fusion, the projectile breaks up and subsequently all the fragments fuse with the target to form a compound.

  2. The dominance of the ν(0d5/22 configuration in the N=8 shell in 12Be from the breakup reaction on a proton target at intermediate energy

    Directory of Open Access Journals (Sweden)

    Le Xuan Chung

    2017-11-01

    Full Text Available The momentum distribution of 11Be fragments produced by the breakup of 12Be interacting with a proton target at 700.5 MeV/u energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the N=8 neutron shell, the momentum distribution of 11Be fragments from the one-neutron knockout Be12(p,pn reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron 0d5/2 orbital in 12Be to the transverse momentum distribution of the 11Be fragments. The single-neutron 0d5/2 spectroscopic factor deduced from the present knock-out data is 1.39(10, which is significantly larger than that deduced recently from data of 12Be breakup on a carbon target. This result provides a strong experimental evidence for the dominance of the neutron ν(0d5/22 configuration in the ground state of 12Be.

  3. The dominance of the ν(0d5/2) 2 configuration in the N = 8 shell in 12Be from the breakup reaction on a proton target at intermediate energy

    Science.gov (United States)

    Chung, Le Xuan; Bertulani, Carlos A.; Egelhof, Peter; Ilieva, Stoyanka; Khoa, Dao T.; Kiselev, Oleg A.

    2017-11-01

    The momentum distribution of 11Be fragments produced by the breakup of 12Be interacting with a proton target at 700.5 MeV/u energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the N = 8 neutron shell, the momentum distribution of 11Be fragments from the one-neutron knockout 12Be (p , pn) reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA) based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron 0d5/2 orbital in 12Be to the transverse momentum distribution of the 11Be fragments. The single-neutron 0d5/2 spectroscopic factor deduced from the present knock-out data is 1.39(10), which is significantly larger than that deduced recently from data of 12Be breakup on a carbon target. This result provides a strong experimental evidence for the dominance of the neutron ν(0d5/2) 2 configuration in the ground state of 12Be.

  4. Classical dynamical modelling of near-barrier breakup

    Science.gov (United States)

    Simpson, E. C.; Cook, K. J.; Kalkal, Sunil; Luong, D. H.; Carter, I. P.; Dasgupta, M.; Hinde, D. J.

    2017-11-01

    The complete fusion of light, weakly-bound nuclides is known to be significantly suppressed with respect to comparable well-bound projectiles or with respect to single barrier penetration model calculations. Strong α-clustering in these light systems mean that they very easily disintegrate into clusters, either via direct excitation of their intrinsic cluster continuum, or via transfer reactions which connect to unbound states in neighbouring nuclides. This breakup is thought to reduce the probability for complete fusion. Here we discuss which processes cause breakup, whether or not breakup happens fast enough, and the interpretation of measurements made at the Australian National University of breakup using classical dynamical models. Understanding the intimate details of breakup, and the resonances through which it proceeds, will be crucial in determining its likely influence on fusion.

  5. Breakup branches of Borromean beryllium-9

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R., E-mail: r.smith.3@pgr.bham.ac.uk; Freer, M.; Wheldon, C.; Curtis, N.; Ashwood, N. I.; Barr, M.; Kokalova, Tz.; Malcolm, J. D.; Ziman, V. A. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Almaraz-Calderon, S.; Aprahamian, A.; Bucher, B.; Couder, M.; Fang, X.; Jung, F.; Lu, W.; Roberts, A.; Tan, W. P. [Institute for Structure and Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Copp, P.; Lesher, S. R. [Department of Physics, University of Wisconsin - La Crosse, La Crosse, WI 54601 (United States); and others

    2015-10-15

    The breakup reaction {sup 9}Be({sup 4}He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in {sup 9}Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in {sup 9}Be have been explored including the {sup 8}Be{sub g.s.} + n, {sup 8}Be{sub 2{sup +}} + n and {sup 5}He{sub g.s.} + {sup 4}He channels. By imposing the condition that the breakup proceeded via the {sup 8}Be ground state, clean excitation spectra for {sup 9}Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose.

  6. Dynamical effects in nuclear collisions in the Fermi energy range: aligned breakup of heavy projectiles[24.75.+i; 25.70.Mn; 25.70.Pq; Heavy ions reactions at intermediate energy; Fragment correlations; Fission and aligned breakup; Deformation and neck instability

    Energy Technology Data Exchange (ETDEWEB)

    Bocage, F.; Colin, J.; Louvel, M.; Auger, G.; Bacri, Ch.O.; Bellaize, N.; Borderie, B.; Bougault, R.; Brou, R.; Buchet, P.; Charvet, J.L.; Chbihi, A.; Cussol, D.; Dayras, R.; De Cesare, N.; Demeyer, A.; Dore, D.; Durand, D.; Frankland, J.D.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Guinet, D.; Lautesse, P.; Laville, J.L.; Lecolley, J.F.; Legrain, R.; Le Neindre, N.; Lopez, O.; Maskay, A.M.; Nalpas, L.; Nguyen, A.D.; Parlog, M.; Peter, J.; Plagnol, E.; Rivet, M.F.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Steckmeyer, J.C.; Stern, M.; Tabacaru, G.; Tamain, B.; Tirel, O.; Tassan-Got, L.; Vient, E.; Vigilante, M.; Volant, C.; Wieleczko, J.P.; Le Brun, C.; Genoux-Lubain, A.; Rudolf, G.; Stuttge, L

    2000-08-28

    Recent experimental results concerning heavy systems (Pb + Au, Pb + Ag, Pb + Al, Gd + C, Gd + U, Xe + Sn, etc) obtained at GANIL with the INDRA and NAUTILUS 4{pi} arrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributions of the fragments. More precisely, we observe an isotropic component which is compatible with the prediction of statistical models and a second one corresponding to breakup aligned with the recoil direction of the projectile like source which should be compared with the predictions of dynamical calculations based on microscopic transport models.

  7. 11Li structural information from inclusive break-up measurements

    Directory of Open Access Journals (Sweden)

    Fernández-García J. P.

    2015-01-01

    Full Text Available Structure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV. The effective break-up energy and the slope of B(E1 distribution close to the threshold have been extracted from the experimental data.

  8. Coulomb breakup of {sup 23}O

    Energy Technology Data Exchange (ETDEWEB)

    Nociforo, C. [Institut fuer Kernchemie, Johannes Gutenberg Universitaet, D-55099 Mainz (Germany)]. E-mail: nociforo@lns.infn.it; Jones, K.L.; Aumann, T.; Datta Pramanik, U.; Emling, H.; Geissel, H.; Hellstroem, M.; Leifels, Y.; Muenzenberg, G.; Suemmerer, K.; Weick, H.; Typel, S. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); Khiem, L.H. [Institut fuer Kernchemie, Johannes Gutenberg Universitaet, D-55099 Mainz (Germany); Adrich, P. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)]|[Instytut Fizyki, Uniwersytet Jagellonski, PL-30-059 Cracow (Poland); Carlson, B.V. [Instituto Tecnologico de Aeronautica, CTA, Sao Jose dos Campos (Brazil); Cortina-Gil, D. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)]|[Universidad de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Elze, Th.W. [Institut fuer Kernphysik, Johann Wolfgang Goethe Universitaet, D-60486 Frankfurt (Germany); Kratz, J.V. [Institut fuer Kernchemie, Johannes Gutenberg Universitaet, D-55099 Mainz (Germany); Kulessa, R. [Instytut Fizyki, Uniwersytet Jagellonski, PL-30-059 Cracow (Poland); Lange, T. [Institut fuer Kernphysik, Johann Wolfgang Goethe Universitaet, D-60486 Frankfurt (Germany); Lenske, H. [Institut fuer Theoretische, Universitaet Giessen, D-35392 Giessen (Germany); Lubkiewicz, E. [Instytut Fizyki, Uniwersytet Jagellonski, PL-30-059 Cracow (Poland); Palit, R. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)]|[Institut fuer Kernphysik, Johann Wolfgang Goethe Universitaet, D-60486 Frankfurt (Germany); Scheit, H. [Max-Planck Institut fuer Kernphysik, D-69029 Heidelberg (Germany); Simon, H. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)]|[Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Wajda, E.; Walus, W. [Instytut Fizyki, Uniwersytet Jagellonski, PL-30-059 Cracow (Poland)

    2005-01-06

    The ground-state structure of the near-drip-line nucleus {sup 23}O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections d{sigma}/dE* for electromagnetic excitation of {sup 23}O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including {gamma} rays. The analysis of the deduced dipole-transition probability into the continuum infers a 2s{sub 1/2}-bar O22(0{sup +}) ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin I{sup {pi}}(O23)=1/2{sup +}, resolving earlier conflicting experimental findings. Final-state interaction is of significant influence, an effective reduced scattering length for low-energy p{sub 3/2} neutron scattering could be derived from the data.

  9. Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values

    Energy Technology Data Exchange (ETDEWEB)

    Monaghan, P; Shneor, R; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Ciofi degli-Atti, C; Cisbani, E; Cosyn, W; Craver, B; de Jager, C W; Feuerbach, R J; Folts, E; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Morita, H; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Ryckebusch, J; Saha, A; Sawatzky, B; Segal, J; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L

    2014-08-01

    The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.

  10. Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values

    CERN Document Server

    Monaghan, P; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Atti, C Ciofi degli; Cisbani, E; Cosyn, W; Craver, B; de Jager, C W; Feuerbach, R J; Folts, E; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Morita, H; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Ryckebusch, J; Saha, A; Sawatzky, B; Segal, J; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L

    2013-01-01

    The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.

  11. Breakup mechanisms for 7Li + 197Au, 204Pb systems at sub-barrier energies

    Directory of Open Access Journals (Sweden)

    Luong D.H.

    2013-12-01

    Full Text Available Coincidence measurements of breakup fragments were carried out for the 7Li + 197Au and 204Pb systems at sub-barrier energies. The mechanisms triggering breakup, and time-scales of each process, were identified through the reaction Q-values and the relative energy of the breakup fragments. Binary breakup of 7Li were found to be predominantly triggered by nucleon transfer, with p-pickup leading to 8Be → α + α decay being the preferred breakup mode. From the time-scales of each process, the coincidence yields were separated into prompt and delayed components, allowing the identification of breakup process important in the suppression of complete fusion of 7Li at above-barrier energies.

  12. Proton-deuteron break-up measurements with BINA at 135 MeV

    NARCIS (Netherlands)

    Eslami-Kalantari, M.; Amir-Ahmadi, H. R.; Biegun, A.; Gasparic, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Moeini, H.; Ramazani-Moghaddam-Arani, A.; Shende, S. V.; Stephan, E.; Sworst, R.

    2009-01-01

    High-precision measurements of the proton-deuteron elastic and break-up reactions have been performed in the past at KVI and elsewhere with the aim to study three-nucleon force (3NF) effects in the break-up scattering process by performing a measurement of vector analyzing powers and differential

  13. Inclusive breakup of three-fragment weakly bound nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, B.V.; Frederico, T. [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Hussein, M.S., E-mail: hussein@if.usp.br [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970 São Paulo, SP (Brazil); Instituto de Física, Universidade de São Paulo, C.P. 66318, 05314-970 São Paulo, SP (Brazil)

    2017-04-10

    The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.

  14. High Energy Break-Up of Few-Nucleon Systems

    Science.gov (United States)

    Sargsian, Misak

    2008-03-01

    We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving 2D and 3He targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.

  15. Breakup of diminutive Rayleigh jets

    NARCIS (Netherlands)

    van Hoeve, W.; Gekle, S.; Snoeijer, Jacobus Hendrikus; Versluis, Michel; Brenner, Michael P.; Lohse, Detlef

    2010-01-01

    Discharging a liquid from a nozzle at sufficient large velocity leads to a continuous jet that due to capillary forces breaks up into droplets. Here we investigate the formation of microdroplets from the breakup of micron-sized jets with ultra high-speed imaging. The diminutive size of the jet

  16. High Energy Break-Up of Few-Nucleon Systems

    OpenAIRE

    Sargsian, Misak M.

    2008-01-01

    We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The...

  17. Elastic and break-up of the 1n-halo 11Be nucleus

    Directory of Open Access Journals (Sweden)

    Di Pietro A.

    2014-03-01

    Full Text Available The elastic and break-up angular distributions of the 10,11Be+64Zn reactions measured at Ec.m.≈1.4 VC have been analysed within the CCDC and O.M. frameworks. The suppression of the Coulomb-nuclear interference, observed in the 11Be scattering case with respect to the 10Be, has been interpreted as due to a long range absorption owing to the coupling with the break-up (Coulomb and nuclear channels. The presence of 10Be events on the 11Be experiment data have been explained as due mainly to break-up processes.

  18. Anatomy of an Asteroid Breakup

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    A team of scientists has observed the breakup of an asteroid as it orbits the Sun. In a new study, they reveal what theyve learned from their ground- and space-based observations of this disintegration.These Hubble images show the fragments of R3 in higher resolution over the span of October 2013 to February 2014. [Jewitt et al. 2017]Observations of DisintegrationActive asteroids are objects that move on asteroid-like orbits while displaying comet-like behavior. The cause of their activity can vary ranging from outgassing as the asteroid heats up in its solar approach, to expelled debris from a collision, to the entire asteroid flying apart because its spinning too fast.Led by David Jewitt (University of California at Los Angeles), a team of scientists has analyzed observations of the disintegrating asteroid P/2013 R3. The observations span two years and were made by a number of telescopes, including Hubble, Keck (in Hawaii), Magellan (in Chile), and the Very Large Telescope (in Chile).A schematic diagram of the different fragments of R3 and how they relate to each other. Black numbers estimate the fragment separation velocities; red numbers estimate the separation date. [Jewitt et al. 2017]Jewitt and collaborators then used these observations and a bit of modeling to understand what asteroid R3 was like originally, what its pieces are doing now, and what caused it to break up.Cause of the BreakupThe team found that P/2013 R3 broke up into at least 13 pieces, the biggest of which was likely no more than 100-200 meters in size. The original asteroid was probably less than 400 m in radius.By measuring the velocities of the fragments in the various observations, Jewitt and collaborators were able to work backward to determine when each piece broke off. They found that the fragmentation process was spread out over the span of roughly 5 months suggesting that the asteroids breakup wasnt impact-related (otherwise the fragmentation would likely have been all at once

  19. Parental Break-Ups and Stress

    DEFF Research Database (Denmark)

    Dissing, Agnete S.; Dich, Nadya; Nybo Andersen, Anne-Marie

    2017-01-01

    Background: Parental break-up is wide spread, and the effects of parental break-up on children’s well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre...... on parental break-up and post break-up family arrangements. Results: Twenty-one percent of the children had experienced a parental break-up at age 11, and those who had experienced parental break-up showed a higher risk of stress (OR:1.72, 95%CI:1.55;1.91) regardless of the child’s age at break-up. Children...... living in a new family with stepparents (OR = 1.63, 95%CI:1.38;1.92), or shared between the parents (OR = 1.48, 95%CI:1.26;1.75) reported higher stress than children of intact families. Single parent families reported markedly higher stress levels than children in intact families (OR = 2.18, 95%CI:1...

  20. Direct and resonant breakup of {sup 6}He on {sup 209}Bi near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Kolata, J.J. [Physics Department, University of Notre Dame, Notre Dame, Indiana, 46556-5670 (United States)

    2007-12-15

    As part of a program to study reactions induced by the two-neutron halo nucleus {sup 6}He on high-Z targets, a neutron-{alpha} particle coincidence experiment was performed for {sup 6}He incident on a {sup 209}Bi target at an energy just above the Coulomb barrier. The experimental setup was optimized for the measurement of projectile breakup. Direct breakup, as well as breakup through the 2{sup +} excited state of {sup 6}He and also the {sup 5}He+n channel, could be distinguished. The total breakup cross section measured in this work compares well with a continuum-discretized coupled-channels calculation that assumes a 50% reduction in the B(E1) computed from a pure {sup 4}He+2n cluster configuration. The B(E2{up_arrow}) for Coulomb excitation of the 2{sup +} state in {sup 6}He was also determined. (Author)

  1. Intrusive Thoughts: A Primary Variable in Breakup Distress

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2013-01-01

    University students who were high versus low on breakup distress scores were given self-report measures to assess their intrusive thoughts about the romantic breakup and their somatic symptoms that followed the breakup as well as their extracurricular activities and social support that might alleviate their breakup distress. In a regression…

  2. Negative Emotions and Behaviors are Markers of Breakup Distress

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

    2013-01-01

    Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

  3. Study of pairing and clusterisation in light nuclei through nuclear break-up

    Directory of Open Access Journals (Sweden)

    Assié Marlène

    2014-03-01

    Full Text Available Nuclear break-up is a powerful tool to investigate nuclear structure as it is sensitive to the quantum properties of the emitted particles. This reaction mechanism has been used to investigate several aspects of correlations. First, the case of 11Be was studied where the spectroscopic factors for the two configurations where extracted. Secondly, the spectroscopic factor for alpha clusterization in the ground state of 40Ca was measured. Finally the correlation between the two neutrons in the halo of 6He emitted through break-up reactions showed strong contribution for the di-neutron configuration.

  4. Study of halo nuclei breakup on light targets at intermediate and high energies

    CERN Document Server

    Parfenova, Ioulia

    2002-01-01

    The study of exotic nuclei is one of the most important topics in modern nuclear physics. It allows general understanding of the structure and nature of light nuclear systems in the vicinity of the driplines. Most of the leading facilities in the world, CERN, GANIL, GSI in Europe, RIKEN in Japan, and NSCL(MSU) in USA, are involved in these investigations. Recently, new experimental data on the properties of light halo nuclei such as extremely large interaction cross sections, huge electromagnetic dissociation cross sections, narrow momentum distribution of fragments from breakup reactions, unusual modes of the beta-decay of these nuclei on the borders of the stability, were obtained. This Thesis is based on a series of articles devoted to theoretical investigations of nuclear breakup reactions with light halo nuclei at intermediate energies impinging on light target nuclei. Special attention is paid to the question of sensitivity of the calculated breakup cross sections and longitudinal momentum distributions...

  5. Dynamical effects in nuclear collisions in the Fermi energy range: aligned breakup of heavy projectiles 24.75.+i; 25.70.Mn; 25.70.Pq; Heavy ions reactions at intermediate energy; Fragment correlations; Fission and aligned breakup; Deformation and neck instability

    CERN Document Server

    Bocage, F; Louvel, M; Auger, G; Bacri, C O; Bellaize, N; Borderie, B; Bougault, R; Brou, R; Buchet, P; Charvet, J L; Chbihi, A; Cussol, D; Dayras, R; De Cesare, N; Demeyer, A N; Doré, D; Durand, D; Frankland, J D; Galíchet, E; Genouin-Duhamel, E; Gerlic, E; Guinet, D; Lautesse, P; Laville, J L; Lecolley, J F; Legrain, R; Le Neindre, N; López, O; Maskay, A M; Nalpas, L; Nguyen, A D; Pârlog, M; Péter, J; Plagnol, E; Rivet, M F; Rosato, E; Saint-Laurent, F; Salou, S; Steckmeyer, J C; Stern, M; Tabacaru, G; Tamain, B; Tirel, O; Tassan-Got, L; Vient, E; Vigilante, M; Volant, C; Wieleczko, J P; Le Brun, C; Genoux-Lubain, A; Rudolf, G; Stuttgé, L

    2000-01-01

    Recent experimental results concerning heavy systems (Pb + Au, Pb + Ag, Pb + Al, Gd + C, Gd + U, Xe + Sn, etc) obtained at GANIL with the INDRA and NAUTILUS 4 pi arrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributio...

  6. Fault linkage and continental breakup

    Science.gov (United States)

    Cresswell, Derren; Lymer, Gaël; Reston, Tim; Stevenson, Carl; Bull, Jonathan; Sawyer, Dale; Morgan, Julia

    2017-04-01

    The magma-poor rifted margin off the west coast of Galicia (NW Spain) has provided some of the key observations in the development of models describing the final stages of rifting and continental breakup. In 2013, we collected a 68 x 20 km 3D seismic survey across the Galicia margin, NE Atlantic. Processing through to 3D Pre-stack Time Migration (12.5 m bin-size) and 3D depth conversion reveals the key structures, including an underlying detachment fault (the S detachment), and the intra-block and inter-block faults. These data reveal multiple phases of faulting, which overlap spatially and temporally, have thinned the crust to between zero and a few km thickness, producing 'basement windows' where crustal basement has been completely pulled apart and sediments lie directly on the mantle. Two approximately N-S trending fault systems are observed: 1) a margin proximal system of two linked faults that are the upward extension (breakaway faults) of the S; in the south they form one surface that splays northward to form two faults with an intervening fault block. These faults were thus demonstrably active at one time rather than sequentially. 2) An oceanward relay structure that shows clear along strike linkage. Faults within the relay trend NE-SW and heavily dissect the basement. The main block bounding faults can be traced from the S detachment through the basement into, and heavily deforming, the syn-rift sediments where they die out, suggesting that the faults propagated up from the S detachment surface. Analysis of the fault heaves and associated maps at different structural levels show complementary fault systems. The pattern of faulting suggests a variation in main tectonic transport direction moving oceanward. This might be interpreted as a temporal change during sequential faulting, however the transfer of extension between faults and the lateral variability of fault blocks suggests that many of the faults across the 3D volume were active at least in part

  7. Systematics of the breakup probability function for {sup 6}Li and {sup 7}Li projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Capurro, O.A., E-mail: capurro@tandar.cnea.gov.ar [Laboratorio TANDAR, Comisión Nacional de Energía Atómica, Av. General Paz 1499, B1650KNA San Martín, Buenos Aires (Argentina); Pacheco, A.J.; Arazi, A. [Laboratorio TANDAR, Comisión Nacional de Energía Atómica, Av. General Paz 1499, B1650KNA San Martín, Buenos Aires (Argentina); CONICET, Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Carnelli, P.F.F. [CONICET, Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Instituto de Investigación e Ingeniería Ambiental, Universidad Nacional de San Martín, 25 de Mayo y Francia, B1650BWA San Martín, Buenos Aires (Argentina); Fernández Niello, J.O. [Laboratorio TANDAR, Comisión Nacional de Energía Atómica, Av. General Paz 1499, B1650KNA San Martín, Buenos Aires (Argentina); CONICET, Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Instituto de Investigación e Ingeniería Ambiental, Universidad Nacional de San Martín, 25 de Mayo y Francia, B1650BWA San Martín, Buenos Aires (Argentina); and others

    2016-01-15

    Experimental non-capture breakup cross sections can be used to determine the probability of projectile and ejectile fragmentation in nuclear reactions involving weakly bound nuclei. Recently, the probability of both type of dissociations has been analyzed in nuclear reactions involving {sup 9}Be projectiles onto various heavy targets at sub-barrier energies. In the present work we extend this kind of systematic analysis to the case of {sup 6}Li and {sup 7}Li projectiles with the purpose of investigating general features of projectile-like breakup probabilities for reactions induced by stable weakly bound nuclei. For that purpose we have obtained the probabilities of projectile and ejectile breakup for a large number of systems, starting from a compilation of the corresponding reported non-capture breakup cross sections. We parametrize the results in accordance with the previous studies for the case of beryllium projectiles, and we discuss their systematic behavior as a function of the projectile, the target mass and the reaction Q-value.

  8. Robustness of free and pinned spiral waves against breakup by electrical forcing in excitable chemical media.

    Science.gov (United States)

    Phantu, Metinee; Sutthiopad, Malee; Luengviriya, Jiraporn; Müller, Stefan C; Luengviriya, Chaiya

    2017-04-01

    We present an investigation on the breakup of free and pinned spiral waves under an applied electrical current in the Belousov-Zhabotinsky reaction. Spiral fronts propagating towards the negative electrode are decelerated. A breakup of the spiral waves occurs when some segments of the fronts are stopped by a sufficiently strong electrical current. In the absence of obstacles (i.e., free spiral waves), the critical value of the electrical current for the wave breakup increases with the excitability of the medium. For spiral waves pinned to circular obstacles, the critical electrical current increases with the obstacle diameter. Analysis of spiral dynamics shows that the enhancement of the robustness against the breakup of both free and pinned spiral waves is originated by the increment of wave speed when either the excitability is strengthened or the obstacle size is enlarged. The experimental findings are reproduced by numerical simulations using the Oregonator model. In addition, the simulations reveal that the robustness against the forced breakup increases with the activator level in both cases of free and pinned spiral waves.

  9. Firm break-up and performance

    Czech Academy of Sciences Publication Activity Database

    Kočenda, Evžen; Hanousek, Jan

    2012-01-01

    Roč. 13, č. 2 (2012), s. 121-143 ISSN 1435-6104 R&D Projects: GA ČR GA402/09/1595 Institutional support: PRVOUK-P23 Keywords : break-up of firms * corporate performance * ownership changes Subject RIV: AH - Economics Impact factor: 0.588, year: 2012

  10. Toward a complete theory for predicting inclusive deuteron breakup away from stability

    OpenAIRE

    Potel, G; Perdikakis, G; CARLSON, B.V.; Atkinson, M. C.; Capel, P.; Dickhoff, W. H.; Escher, J. E.; Hussein, M.S.; Lei, J.; W. Li; Macchiavelli, A. O.; Moro, A. M.; Nunes, F.M.; Pain, S.D.; Rotureau, J.

    2017-01-01

    We present an account of the current status of the theoretical treatment of inclusive $(d,p)$ reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the ...

  11. The H + HeH(+) → He + H2(+) reaction from the ultra-cold regime to the three-body breakup: exact quantum mechanical integral cross sections and rate constants.

    Science.gov (United States)

    De Fazio, Dario

    2014-06-21

    In this work, we present a quantum mechanical scattering study of the title reaction from 1 mK to 2000 K. Total integral cross sections and thermal rate constants are compared with previous theoretical and experimental data and with simpler theoretical models to understand the range of validity of the approximations used in the previous studies. The obtained quantum reactive observables have been found to be nearly insensitive to the roto-vibrational energy of the reactants at high temperatures. More sensitive to the reactant's roto-vibrational energy are the data in the cold and ultra-cold regimes. The implications of the new data presented here in the early universe scenario are also discussed and analyzed.

  12. Ice breakup: Observations of the acoustic signal

    Science.gov (United States)

    Waddell, S. R.; Farmer, D. M.

    1988-03-01

    We describe observations of ambient sound beneath landfast ice in the Canadian Arctic Archipelago and interpret its evolution over the period June-August in terms of ice cracking and disintegration. The data were recorded on six bands between 50 and 14,500 Hz for the period April 2 to August 7, 1986, in Dolphin and Union Strait. The frequency dependence of the attenuation of sound in water allows separation of distant and local noise sources. In conjunction with satellite imagery and meteorological data, it is shown that strong signals in the acoustic time series are associated with major breakup events. The acoustic signal can provide predictive information about ice conditions and the approach of breakup.

  13. Fractal aggregation and breakup of fine particles

    Directory of Open Access Journals (Sweden)

    Li Bingru

    2016-01-01

    Full Text Available Breakup may exert a controlling influence on particle size distributions and particles either are fractured or are eroded particle-by-particle through shear. The shear-induced breakage of fine particles in turbulent conditions is investigated using Taylor-expansion moment method. Their equations have been derived in continuous form in terms of the number density function with particle volume. It suitable for future implementation in computational fluid dynamics modeling.

  14. Capillary breakup of fluid threads within confinement

    Science.gov (United States)

    Hu, Guoqing; Xue, Chundong; Chen, Xiaodong

    2016-11-01

    Fluid thread breakup is a widespread phenomenon in nature, industry, and daily life. Driven by surface tension (or capillarity) at low flow-rate condition, the breakup scenario is usually called capillary instability or Plateau-Rayleigh instability. Fluid thread deforms under confinement of ambient fluid to form a fluid neck. Thinning of the neck at low flow-rate condition is quasistatic until the interface becomes unstable and collapses to breakup. Underlying mechanisms and universalities of both the stable and unstable thinning remain, however, unclear and even contradictory. Here we conduct new numerical and experimental studies to show that confined interfaces are not only stabilized but also destabilized by capillarity at low flow-rate condition. Capillary stabilization is attributed to confinement-determined internal pressure that is higher than capillary pressure along the neck. Two origins of capillary destabilization are identified: one is confinement-induced gradient of capillary pressure along the interface; the other is the competition between local capillary pressure and internal pressure. This work was supported by National Natural Science Foundation of China (Grant No. 11402274, 11272321, and 11572334).

  15. Extracting three-body breakup observables from continuum-discretized coupled-channels calculations with core excitations

    Science.gov (United States)

    de Diego, R.; Crespo, R.; Moro, A. M.

    2017-04-01

    Background: Core-excitation effects in the scattering of two-body halo nuclei have been investigated in previous works. In particular, these effects have been found to affect in a significant way the breakup cross sections of neutron-halo nuclei with a deformed core. To account for these effects, appropriate extensions of the continuum-discretized coupled-channels (CDCC) method have been recently proposed. Purpose: We aim to extend these studies to the case of breakup reactions measured under complete kinematics or semi-inclusive reactions in which only the angular or energy distribution of one of the outgoing fragments is measured. Method: We use the standard CDCC method as well as its extended version with core excitations, assuming a pseudostate basis for describing the projectile states. Two- and three-body observables are computed by projecting the discrete two-body breakup amplitudes, obtained within these reaction frameworks, onto two-body scattering states with definite relative momentum of the outgoing fragments and a definite state of the core nucleus. Results: Our working example is the one-neutron halo 11Be. Breakup reactions on protons and 64Zn targets are studied at 63.7 MeV/nucleon and 28.7 MeV, respectively. These energies, for which experimental data exist, and the targets provide two different scenarios where the angular and energy distributions of the fragments are computed. The importance of core dynamical effects is also compared for both cases. Conclusions: The presented method provides a tool to compute double and triple differential cross sections for outgoing fragments following the breakup of a two-body projectile and might be useful to analyze breakup reactions with other deformed weakly bound nuclei, for which core excitations are expected to play a role. We have found that, while dynamical core excitations are important for the proton target at intermediate energies, they are very small for the Zn target at energies around the Coulomb

  16. Coulomb breakup of the neutron-rich isotopes {sup 15}C and {sup 17}C

    Energy Technology Data Exchange (ETDEWEB)

    Datta Pramanik, U.; Aumann, T.; Boretzky, K.; Carlson, B.V.; Cortina, D.; Elze, Th.W.; Emling, H.; Geissel, H.; Gruenschloss, A.; Hellstroem, M.; Ilievski, S.; Kratz, J.V.; Kulessa, R.; Leifels, Y.; Leistenschneider, A.; Lubkiewicz, E.; Muenzenberg, G.; Reiter, P.; Simon, H.; Suemmerer, K.; Wajda, E.; Walus, W

    2003-01-02

    Coulomb breakup of unstable neutron-rich carbon isotopes {sup 15,17}C has been studied at energies around {approx}500-600 MeV/nucleon. Non-resonant low-lying dipole strength is observed in these isotopes which can be explained by a direct breakup mechanism. In addition to the decay neutron from excited projectile, {gamma}-rays emitted from excited fragments after Coulomb breakup are measured in coincidence, giving access to quantitative spectroscopic information. The spectroscopic factor deduced for a valence neutron occupying the s{sub 1/2} level in the {sup 15}C ground state is consistent with that obtained earlier from (d,p) transfer reactions. The analysis for Coulomb breakup of {sup 17}C shows that most of the cross section yields the {sup 16}C core in excited states. The predominant ground-state configuration of {sup 17}C is found to be {sup 16}C(2{sup +}) x {nu}{sub sd}.

  17. 11Li Breakup on 208Pb at Energies Around the Coulomb Barrier

    DEFF Research Database (Denmark)

    Fernández-García, J.P.; Cubero, M.; Rodríguez-Gallardo, M.

    2013-01-01

    The inclusive breakup for the 11Li+208Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of 9Li following the 11Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbatio...

  18. Breakup of 42 MeV 7 Li projectiles in the fields of 12 C and 197 Au ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Inclusive cross sections of particles and tritons from the breakup of 42 MeV 7Li by 12C and 197Au targets are presented and analysed in the framework of the Serber model. Spectral distortions due to the targets and relevant reaction mechanisms are discussed.

  19. Toward a complete theory for predicting inclusive deuteron breakup away from stability

    Energy Technology Data Exchange (ETDEWEB)

    Potel, G.; Li, W.; Rotureau, J. [Michigan State University, Facility for Rare Isotope Beams, East Lansing, MI (United States); Perdikakis, G. [Michigan State University, Facility for Rare Isotope Beams, East Lansing, MI (United States); Central Michigan University, Department of Physics, Mt. Pleasant, MI (United States); Center for the Evolution of the Elements, Joint Institute for Nuclear Astrophysics, East Lansing, MI (United States); Carlson, B.V. [DCTA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil); Atkinson, M.C.; Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, MO (United States); Escher, J.E. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Hussein, M.S. [DCTA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil); Universidade de Sao Paulo, Departamento de Fisica Matematica, Instituto de Fisica, Sao Paulo, SP (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, Sao Paulo, SP (Brazil); Lei, J.; Moro, A.M. [Universidad de Sevilla, Departamento de FAMN, Sevilla (Spain); Macchiavelli, A.O. [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Nunes, F.M. [Michigan State University, Facility for Rare Isotope Beams, East Lansing, MI (United States); Michigan State University, Department of Physics and Astronomy, East Lansing, MI (United States); Pain, S.D. [Oak Ridge National Laboratory, Physics Division, Oak Ridge, TN (United States)

    2017-09-15

    We present an account of the current status of the theoretical treatment of inclusive (d, p) reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations. The different implementations have been benchmarked for the first time, and then applied to the Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies. The accuracy of the description of different reaction observables is assessed by comparing with experimental data of (d, p) on {sup 40,48}Ca. We discuss the predictions of the model for the extreme case of an isotope ({sup 60}Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB). We explore the use of (d, p) reactions as surrogates for (n,γ) processes, by using the formalism to describe the compound nucleus formation in a (d,pγ) reaction as a function of excitation energy, spin, and parity. The subsequent decay is then computed within a Hauser-Feshbach formalism. Comparisons between the (d,pγ) and (n,γ) induced gamma decay spectra are discussed to inform efforts to infer neutron captures from (d,pγ) reactions. Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory. (orig.)

  20. Implicit negative evaluations about ex-partner predicts break-up adjustment: the brighter side of dark cognitions.

    Science.gov (United States)

    Fagundes, Christopher P

    2011-01-01

    Using a subliminal priming lexical decision task, the present research investigated whether individuals who show negative implicit evaluations of an ex-partner immediately after a break-up show superior post-break-up emotional adjustment. As expected, individuals whose reaction times indicated negative implicit evaluations of their ex-partner showed reduced depressive affect immediately after the break-up. Individuals who did not initiate their break-up demonstrated less negative implicit evaluations of their ex-partners as well as more depressive affect. Finally, increased negative implicit evaluations of ex-partners over a one-month period were associated with corresponding improvements in adjustment. The findings demonstrate a critical role for implicit evaluations in post-break-up adjustment. © 2010 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

  1. 24 CFR 982.315 - Family break-up.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Family break-up. 982.315 Section... SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Leasing a Unit § 982.315 Family break-up... assistance in the program if the family breaks up. The PHA administrative plan must state PHA policies on how...

  2. Tear film break-up time in rabbits.

    Science.gov (United States)

    Wei, Xiaojia E; Markoulli, Maria; Zhao, Zhenjun; Willcox, Mark D P

    2013-01-01

    Rabbits have a longer inter-blink time (approximately 10 minutes) compared with humans (five to eight seconds), suggesting that rabbits have a much more stable tear film. Using fluorescein, the tear break-up time of rabbits has been reported to be similar to that of humans. This study set out to measure the tear break-up time in rabbits using non-invasive methods and to establish the pattern of tear break-up compared to humans. The tear break-up time was measured and the pattern of tear break-up was observed in six New Zealand White rabbits on two separate occasions using both the Keeler Tearscope-plus(TM) and a slitlamp biomicroscope. The mean rabbit tear break-up time was 29.8 ± 3.4 (SD) minutes. This contrasts with the reports of human tear break-up time of eight to 30 seconds. The tear breaking spread very slowly and was often restricted to the area of the initial break. Rabbit tears have a significantly higher tear break-up time than humans and this aligns with previously demonstrated differences in inter-blink time between rabbits and humans. Understanding the underlying mechanisms of tear stability may lead to novel ways of increasing human tear film stability. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

  3. Breakup Effects on University Students' Perceived Academic Performance

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2012-01-01

    The Problem: Problems that might be expected to affect perceived academic performance were studied in a sample of 283 university students. Results: Breakup Distress Scale scores, less time since the breakup and no new relationship contributed to 16% of the variance on perceived academic performance. Variables that were related to academic…

  4. Dynamics of droplet breakup in a T-junction

    NARCIS (Netherlands)

    Hoang, D.A.; Portela, L.M.; Kleijn, C.R.; Kreutzer, M.T.; Van Steijn, V.

    2013-01-01

    The breakup of droplets due to creeping motion in a confined microchannel geometry is studied using three-dimensional numerical simulations. Analogously to unconfined droplets, there exist two distinct breakup phases: (i) a quasi-steady droplet deformation driven by the externally applied flow; and

  5. Breakup of radioactive nuclear beams at intermediate energies as indirect method for nuclear astrophysics

    Science.gov (United States)

    Trache, L.; Carstoiu, F.; Gagliardi, C. A.; Tribble, R. E.; Banu, A.

    2008-05-01

    We discuss the use of one-nucleon removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These breakup reactions are good spectroscopic tools and can be used to study a large number of loosely bound proton- or neutron-rich nuclei over a wide range of beam energies. They are peripheral processes that can be used to extract asymptotic normalization coefficients (ANC) from which direct capture proton reaction rates of astrophysical interest can be calculated parameter free. We emphasize the importance of reaction model calculations and of exclusive measurements to check them. We review several cases: the breakup of 8B, 9C, 15C and 23Al. Firrst we review how we have used the data for the breakup of 8B at energies from 30 to 1000 MeV/nucleon on light and heavy targets to extract the astrophysical factor S17(0) = 18.7+/-1.9 eV.b for the key reaction for solar neutrino production. Glauber model calculations in the eikonal approximation and in the optical limit using different effective NN interactions were found to give consistent, though slightly different results, for both 8B and 9C cases, enabling also us to evaluate the precision of the method. The third case is that of a neutron-rich nucleus and the ANC alone does not lead to unambiguous estimates of the associated (n,γ) capture reaction. The 23Al case is that of an sd-shell nucleus, suspected of halo properties, for which our recent GANIL experiment revealed a complex configuration mixing in its ground state. The method outlined here has the big advantage that it can be used for beams of low quality, such as cocktail beams, and intensities as low as a few pps. As such it is very appropriate for the existing and future radioactive beam facilities. The breakup reactions are therefore complementary or a very good alternative to the use of proton and neutron transfer reactions (the ANC method) which require radioactive nuclear beams of much better purity and

  6. A theoretical study of deuteron-induced surrogate reactions

    Science.gov (United States)

    Carlson, B. V.; Capote, R.; Sin, M.

    2017-09-01

    We use the zero-range post-form DWBA approximation to calculate deuteron elastic and nonelastic breakup cross sections and estimate the breakup-fusion cross section that could serve as a surrogate for a neutron-induced reaction cross section. We compare the angular momentum dependence of the breakup-fusion compound nucleus formation cross section with that of the corresponding neutron-induced cross section.

  7. A theoretical study of deuteron-induced surrogate reactions

    Directory of Open Access Journals (Sweden)

    Carlson B.V.

    2017-01-01

    Full Text Available We use the zero-range post-form DWBA approximation to calculate deuteron elastic and nonelastic breakup cross sections and estimate the breakup-fusion cross section that could serve as a surrogate for a neutron-induced reaction cross section. We compare the angular momentum dependence of the breakup-fusion compound nucleus formation cross section with that of the corresponding neutron-induced cross section.

  8. Automatic assessment of tear film break-up dynamics.

    Science.gov (United States)

    Ramos, L; Barreira, N; Pena-Verdeal, H; Giráldez, M J

    2014-01-01

    Dry eye syndrome is a common disorder of the tear film which affects a remarkable percentage of the population. The Break-Up Time (BUT) is a clinical test used for the diagnosis of this disease, which computes the time the first tear film break-up appears. This work describes a fully automatic methodology to compute the BUT measurement and evaluate the break-up dynamics until the final blink. This analysis provides useful additional information for the assessment of tear film stability.

  9. Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction

    Science.gov (United States)

    Sargsian, Misak

    2008-10-01

    We discus recent developments in theory of high energy two-body break-up of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon between two outgoing nucleons. This final state hard rescattering can be expressed through the hard NN scattering amplitude. Within HRM we discuss hard break-up reactions involving D and 3He targets and demonstrate how these reactions are sensitive to the dynamics of hard pn and pp interaction. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.

  10. Experiments on Breakup of Bubbles in a Turbulent Flow.

    Czech Academy of Sciences Publication Activity Database

    Vejražka, Jiří; Zedníková, Mária; Stanovský, Petr

    2018-01-01

    Roč. 64, č. 2 (2018), s. 740-757 ISSN 0001-1541 Institutional support: RVO:67985858 Keywords : bubble * breakup * turbulence Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.836, year: 2016

  11. Surfactant-laden drop jellyfish-breakup mode induced by the Marangoni effect

    Science.gov (United States)

    Zhao, Hui; Zhang, Wen-Bin; Xu, Jian-Liang; Li, Wei-Feng; Liu, Hai-Feng

    2017-03-01

    Drop breakup is a familiar event in both nature and technology. In this study, we find that the bag breakup mode can be replaced by a new breakup mode: jellyfish breakup, when the surfactant concentration of a surfactant-laden drop is high. This new breakup mode has a morphology resembling a jellyfish with many long tentacles. This is due to the inhomogeneous distribution of surfactant in the process of drop deformation and breakup. The thin film of liquid can remain stable as a result of the Marangoni effect. Finally, we propose that the dimensionless surfactant concentration can serve as a criterion for breakup mechanisms.

  12. Blinking and tear break-up during four visual tasks.

    Science.gov (United States)

    Himebaugh, Nikole L; Begley, Carolyn G; Bradley, Arthur; Wilkinson, Jenni A

    2009-02-01

    This study investigates the relationship between blinking, tear film break-up, and ocular symptoms for normal and dry eye subjects performing four different visual tasks. Sixteen control and sixteen dry eye subjects performed four visual tasks (looking straight ahead, watching a movie, identifying rapidly changing letters, and playing a computer game) while blink patterns and fluorescein images of the tear film were videotaped. Pre and posttesting symptom questionnaires, querying the intensity of nine symptoms of ocular irritation, were completed by all subjects. Blink rate and blink amplitude were computed from digitized videos. The percentage of tear film break-up before the blink was calculated. Dry eye subjects had a significantly higher blink rate (p = 0.017, t-test). Both groups blinked significantly less during the game and letter tasks (p break-up in normal subjects was typically inferior; whereas dry eye subjects showed more tear break-up centrally and superiorly. Real-time video recording of tear break-up and blink behavior pointed to complex interaction between the two. Dry eye subjects shifted more toward intense ocular symptoms at posttesting (p break-up during normal visual tasks may explain the increased level of ocular discomfort symptoms reported at the end of the day, particularly in dry eye patients.

  13. Regenerative Beam Breakup in Multi-Pass Electron Accelerators.

    Science.gov (United States)

    Vetter, Arthur Malcolm, Jr.

    1980-12-01

    Important electron coincidence experiments in the 1 to 2 GeV range require electron beams of high intensity and high duty factor. To provide such beams, multi-pass electron accelerator systems are being developed at many laboratories. The beam current in multi-pass electron machines is limited by beam breakup which arises from interaction of the electron beam with deflection modes of the accelerator structure. Achieving high beam intensity (50 to 100 (mu)A) will require detailed understanding and careful control of beam breakup phenomena, and is the subject of this thesis. The TM(,11)-like traveling wave theory is applied to obtain a physical understanding of beam-mode interactions and the principles of focussing in simple two-pass systems, and is used as a basis for general studies of the dependence of starting current on accelerator parameters in systems of many passes. The concepts developed are applied in analyzing beam breakup in the superconducting recyclotron at Stanford. Measurements of beam interactions with selected breakup modes are incorporated in a simple model in order to estimate relative strengths of breakup modes and to predict starting currents in five-pass operation. The improvement over these predicted currents required in order to obtain 50 to 100 (mu)A beams is shown to be achievable with a combination of increased breakup mode loading and improved beam optics.

  14. Neutron correlations in {sup 6}He viewed through nuclear break-up

    Energy Technology Data Exchange (ETDEWEB)

    Assie, M.; Scarpaci, J.A.; Beaumel, D.; Blumenfeld, Y.; Chabot, M.; Iwasaki, H.; Marechal, F.; Monrozeau, C.; Petrache, C.; Skaza, F.; Tuna, T. [Universite Paris-Sud-11-CNRS/IN2P3, Institut de Physique Nucleaire, Orsay (France); Lacroix, D. [GANIL, Caen (France); Angelique, J.C. [LPC/ENSICAEN, Caen (France); Bazin, D. [Michigan State University, National Superconducting Cyclotron Laboratory, East-Lansing, MI (United States); Catford, W.N. [University of Surrey, School of Electronics and Physical Sciences, Guildford (United Kingdom); Chatterjee, A. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Fallot, M. [Subatech, Nantes (France); Mengoni, D. [Universita di Camerino (Italy); INFN, Sezione di Perugia, Dipartimento di Fisica, Camerino (Italy); Nyberg, J. [Uppsala University, Department of Physics and Astronomy, Uppsala (Sweden)

    2009-12-15

    The nuclear break-up of {sup 6}He on a {sup 208}Pb target was studied at 20A MeV using a secondary beam of {sup 6}He produced by the SPIRAL facility at GANIL. {alpha} -particles were detected in coincidence with two neutrons with a large angular coverage and the reaction mechanism was identified. From the distribution of the relative angles between the two neutrons the correlation function was extracted. It shows a strong correlation at small relative angles attributed to the contribution of the di-neutron configuration of {sup 6}He. (orig.)

  15. Imaging three-body breakup involving two identical fragments

    Science.gov (United States)

    Feizollah, Peyman; Severt, T.; Jochim, Bethany; Berry, Ben; Kanaka Raju, P.; Zohrabi, M.; Rajput, Jyoti; Ablikim, U.; Kaderiya, B.; Ziaee, Farzaneh; Rudenko, A.; Rolles, D.; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.

    2017-04-01

    We study the strong-field fragmentation of CO2 and CO2+ into C++O++O+ as examples of three-body breakup involving two identical fragments. This process can happen through concerted- or sequential-breakup mechanisms. In concerted breakup, the two O+ fragments play indistinguishable roles. In sequential breakup, however, one of the O+ fragments comes from the first fragmentation step of CO23+, and the other one comes from unimolecular dissociation of CO2+ in the second step. Therefore, in sequential breakup the two O+ fragments may be distinguished. A method is proposed that allows us to separate the concerted and sequential processes when the lifetime of the intermediate molecule is much longer than its rotational period. As a result, it is possible to experimentally distinguish the two O+ fragments in the sequential process. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy.

  16. Investigation on Electrostatical Breakup of Bio-Oil Droplets

    Directory of Open Access Journals (Sweden)

    John Z. Wen

    2012-10-01

    Full Text Available In electrostatic atomization, the input electrical energy causes breaking up of the droplet surface by utilizing a mutual repulsion of net charges accumulating on that surface. In this work a number of key parameters controlling the bio-oil droplet breakup process are identified and these correlations among the droplet size distribution, specific charges of droplets and externally applied electrical voltages are quantified. Theoretical considerations of the bag or strip breakup mechanism of biodiesel droplets experiencing electrostatic potential are compared to experimental outcomes. The theoretical analysis suggests the droplet breakup process is governed by the Rayleigh instability condition, which reveals the effects of droplets size, specific charge, surface tension force, and droplet velocities. Experiments confirm that the average droplet diameters decrease with increasing specific charges and this decreasing tendency is non-monotonic due to the motion of satellite drops in the non-uniform electrical field. The measured specific charges are found to be smaller than the theoretical values. And the energy transformation from the electrical energy to surface energy, in addition to the energy loss, Taylor instability breakup, non-excess polarization and some system errors, accounts for this discrepancy. The electrostatic force is the dominant factor controlling the mechanism of biodiesel breakup in electrostatic atomization.

  17. Coulomb and Nuclear Breakup at Low Energies: Scaling Laws

    Directory of Open Access Journals (Sweden)

    Hussein M. S.

    2013-12-01

    Full Text Available We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei.

  18. Modeling Tear Film Evaporation and Breakup with Duplex Films

    Science.gov (United States)

    Stapf, Michael; Braun, Richard; Begley, Carolyn; Driscoll, Tobin; King-Smith, Peter Ewen

    2015-11-01

    Tear film thinning, hyperosmolarity, and breakup can irritate and damage the ocular surface. Recent research hypothesizes deficiencies in the lipid layer may cause locally increased evaporation, inducing conditions for breakup. We consider a model for team film evolution incorporating two mobile fluid layers, the aqueous and lipid layers. In addition, we include the effects of salt concentration, osmosis, evaporation as modified by the lipid layer, and the polar portion of the lipid layer. Numerically solving the resulting model, we explore the conditions for tear film breakup and analyze the response of the system to changes in our parameters. Our studies indicate sufficiently fast peak values or sufficiently wide areas of evaporation promote TBU, as does diffusion of solutes. In addition, the Marangoni effect representing polar lipids dominates viscous dissipation from the non-polar lipid layer in the model. This work was supported in part by NSF grant 1412085 and NIH grant 1R01EY021794.

  19. V3 CMS tracker layout Detector Break-up

    CERN Document Server

    Caner, Alessandra

    1996-01-01

    This note reports on the detector and channel break-up of the CMS V3 tracker layout. A compilation of alternative layouts is also tabulated to allow for cost estimates as a function of layout configurations. The information is organized in a modular fashion: for each configuration, the break-up of 25 cm ( 'one wheel') of barrel is reported. The forward detectors ( 'disks') are described individually as a function of equipped annuli. The total number of channels, the area and the bare cost of the provisional V3 layout are estimated. This note will be updated as the V3 layout evolves.

  20. Influence of projectile breakup on complete fusion

    Indian Academy of Sciences (India)

    Complete fusion excitation functions for 11,10B+159Tb and 6,7Li+159Tb have been reported at energies around the respective Coulomb barriers. The measurements show significant suppression of complete fusion cross-sections at energies above the barrier for 10B+159Tb and 6,7Li+159Tb reactions, when compared to ...

  1. Numerical simulation of breakup and detachment of an axially ...

    Indian Academy of Sciences (India)

    The extensional, breakup and detachment dynamics of an axially stretching Newtonian liquid bridge are investigated numerically with a dynamic domain multiphase incompressible flow solver. The multiphase flow solver employs a Cahn–Hilliard phase field model to describe the evolution of the diffuse interfaceseparating ...

  2. Breakup of New Orleans Households after Hurricane Katrina

    Science.gov (United States)

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

  3. Droplet Breakup Dynamics in Bi-Layer Bifurcating Microchannel

    Directory of Open Access Journals (Sweden)

    Yong Ren

    2018-01-01

    Full Text Available Breakup of droplets at bi-layer bifurcating junction in polydimethylsiloxane (PDMS microchannel has been investigated by experiments and numerical simulation. The pressure drop in bi-layer bifurcating channel was investigated and compared with single-layer bifurcating channel. Daughter droplet size variation generated in bi-layer bifurcating microchannel was analyzed. The correlation was proposed to predict the transition between breakup and non-breakup conditions of droplets in bi-layer bifurcating channel using a phase diagram. In the non-breakup regime, droplets exiting port can be switched via tuning flow resistance by controlling radius of curvature, and or channel height ratio. Compared with single-layer bifurcating junction, 3-D cutting in diagonal direction from bi-layer bifurcating junction induces asymmetric fission to form daughter droplets with distinct sizes while each size has good monodispersity. Lower pressure drop is required in the new microsystem. The understanding of the droplet fission in the novel microstructure will enable more versatile control over the emulsion formation, fission and sorting. The model system can be developed to investigate the encapsulation and release kinetics of emulsion templated particles such as drug encapsulated microcapsules as they flow through complex porous media structures, such as blood capillaries or the porous tissue structures, which feature with bifurcating junctions.

  4. A fundamental study of liquid phase particle breakup. Revision

    Science.gov (United States)

    1984-12-01

    Combustion efficiency of aluminized propellants in solid rocket motors is reduced by incomplete aluminum combustion and two-phase nozzle flow losses. Combustion of these propellants can produce large Al/Al2O3 agglomerates. As a direct result of agglomerate breakup, the aluminum combustion rate is increased, and the thermal energy released is more efficiently transferred into exhaust kinetic energy. This research sought to obtain physical data to characterize the mechanisms of aerodynamic droplet breakup. Experiments have been completed in which conventional liquids and a liquid metal (mercury) was studied. The primary goal of the conventional liquid experiments was to examine the effect of liquid properties (viscosity and surface tension) on the breakup mechanism, time scale, and fragment size distribution. The goal of the mercury experiments was to examine the effect of the much higher surface tension more characteristic of liquid aluminum. A key element of the experimental effort is the use of nonintrusive laser diagnostics including pulsed laser holography (PLH) and laser Doppler velocimetry (LDV). The exceptional temporal and spatial resolution of PLH provided the ability to resolve the mechanism of breakup and the size distribution of the fragments. LDV was used to determine drop velocity distributions along the nozzle revealing the rapid acceleration of the flattened droplets and then, surprisingly, the milder acceleration of the fragments.

  5. FAMILY DYNAMICS, FAMILY BREAKUPS, AND THEIR IMPACTS ON CHILDREN

    Directory of Open Access Journals (Sweden)

    Yayah Khisbiyah

    2016-09-01

    Full Text Available The number of family breakups has been increasing in the last few decade, particularly in the developed, industrial world. By far the highest divorce rate in the industrial countries is that of the United States. According to current rates, about half of all American marriages are dissolved.

  6. THE INFLUENCE OF GAS-DENSITY AND LIQUID PROPERTIES ON BUBBLE BREAKUP

    NARCIS (Netherlands)

    WILKINSON, PM; VANSCHAYK, A; SPRONKEN, JPM; VANDIERENDONCK, LL

    On the basis of a literature review of bubble breakup experiments, it is demonstrated that both liquid viscosity and surface tension have an influence on bubble stability and, thus, bubble breakup, for small as well as large bubbles. Possible influences of the gas properties on bubble breakup have

  7. Direct numerical simulation of three-dimensional liquid jet breakup

    Science.gov (United States)

    Constante, Ricardo; Kahouadji, Lyes; Nicolle, Andre; Chergui, Jalel; Juric, Damir; Shin, Seungwon; Matar, Omar K.

    2017-11-01

    We carry out direct numerical simulations of liquid jet dynamics and breakup using a high-performance code, Blue, which uses a hybrid technique based on the front-tracking and the level-set method; it defines the interface position through a marker function and a local triangular Lagrangian mesh. Liquid jet breakup is an example of interfacial complexity associated with multiphase flows because of the formation of ligaments and their pinch off to give rise to droplet formation. We consider the atomisation of a liquid jet released into a stagnant gas phase where the velocity is stimulated sinusoidally to promote the growth of Kelvin-Helmholtz instabilities, thus forming a flow system characterized by complex interfaces. The spread of cylindrical liquid jet into a coflowing external stream is also considered (essentially, a replication of the Marmottant and Villermaux experimental work). Funding from BP gratefully acknowledged.

  8. COBBOOM: The Continental Breakup and Birth of Oceans Mission

    Directory of Open Access Journals (Sweden)

    Joann M. Stock

    2007-09-01

    Full Text Available The rupture of continents and creation of new oceans is a fundamental yet primitively understood aspect of the plate tectonic cycle. Building upon past achievements by ocean drilling and geophysical and geologic studies, we propose “The Continental Breakup and Birth of Oceans Mission (COBBOOM” as the next major phase of discovery, for which sampling by drilling will be essential.In September 2006, fifty-one scientists from six continents gathered in Pontresina, Switzerland to discuss current knowledge of continental breakup and sedimentary basin formation and how the Integrated Ocean Drilling Program (IODP can deepen that knowledge Coffin et al., 2006. Workshop participants discussed a global array of rifted margins (Fig. 1, formulated the critical problems to beaddressed by future drilling and related investigations, and identified key rift systems poised for IODP investigations. 

  9. Improvement of Jet Breakup Model in Fuel Coolant Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Kwang Hyun; Kim, Kyung Kyu; Nam, Yang Ho [Korea Maritime Univ., Jinhae (Korea, Republic of)

    2007-02-15

    The objective of this work is to improve TRACER-II code in conjunction with the OECD SERENA project for validation of vapor explosion analysis codes. FCI breakup model is to be improved by building four-fluid multiphase flow model and existing models and experimental data are examined for the validation of the model. Four-fluid multiphase flow model has been built in TRACER-II code and jet breakup model has been included. Kelvin-Helmholtz instability is modelled for the jet side and boundary layer stripping is modelled for the jet leading edge. This work can contributes to the reduction of uncertainty in the FCI models for reactor safety analysis.

  10. Viscous Particle Breakup within a Cooling Nuclear Fireball

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lock Haven Univ., Lock Haven, PA (United States); Knight, K. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dai, Z. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ramon, C. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Reid, J. D. [Lock Haven Univ., Lock Haven, PA (United States)

    2016-10-04

    Following the surface detonation of a nuclear weapon, the Earth’s crust and immediate surroundings are drawn into the fireball and form melts. Fallout is formed as these melts incorporate radioactive material from the bomb vapor and cool rapidly. The resultant fallout plume and dispersion of radioactive contamination is a function of several factors including weather patterns and fallout particle shapes and size distributions. Accurate modeling of the size distributions of fallout forms an important data point for dispersion codes that calculate the aerial distribution of fallout. While morphological evidence for aggregation of molten droplets is well documented in fallout glass populations, the breakup of these molten droplets has not been similarly studied. This study documents evidence that quenched fallout populations preserve evidence of molten breakup mechanisms.

  11. Peregrine soliton generation and breakup in standard telecommunications fiber.

    Science.gov (United States)

    Hammani, Kamal; Kibler, Bertrand; Finot, Christophe; Morin, Philippe; Fatome, Julien; Dudley, John M; Millot, Guy

    2011-01-15

    We present experimental and numerical results showing the generation and breakup of the Peregrine soliton in standard telecommunications fiber. The impact of nonideal initial conditions is studied through direct cutback measurements of the longitudinal evolution of the emerging soliton dynamics and is shown to be associated with the splitting of the Peregrine soliton into two subpulses, with each subpulse itself exhibiting Peregrine soliton characteristics. Experimental results are in good agreement with simulations.

  12. Radial electron-beam-breakup transit-time oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Mostrom, M.A. [Mission Research Corp., Albuquerque, NM (United States); Kwan, T.J.T. [Los Alamos National Lab., NM (United States)

    1995-01-01

    A new radially-driven electron-beam-breakup transit-time oscillator has been investigated analytically and through computer simulation as a compact low-impedance high-power microwave generator. In a 1MV, 50kA device 35cm in radius and 15cm long, with no external magnetic field, 5GW of extracted power and a growth rate of 0.26/ns have been observed. Theoretical maximum efficiencies are several times higher.

  13. Break-up of New Orleans Households after Hurricane Katrina

    OpenAIRE

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household break-up due to Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads and non–household heads (N = 242), traced just over a year later, with a matched sample from a nationally representative survey over an equivalent period. ...

  14. Bubble Coalescence and Breakup Modeling for Computing Mass Transfer Coefficient

    OpenAIRE

    Mawson, Ryan A.

    2012-01-01

    There exist several different numerical models for predicting bubble coalescence and breakup using computational fluid dynamics (CFD). Various combinations of these models will be employed to model a bioreactor process in a stirred reactor tank. A mass transfer coefficient, Kla, has been calculated and compared to those found experimentally by Thermo-Fisher Scientific, to validate the accuracy of currently available mathematical models for population balance equations. These include various c...

  15. An analysis of the 2016 Hitomi breakup event

    Science.gov (United States)

    Flegel, Sven; Bennett, James; Lachut, Michael; Möckel, Marek; Smith, Craig

    2017-04-01

    The breakup of Hitomi (ASTRO-H) on 26 March 2016 is analysed. Debris from the fragmentation is used to estimate the time of the event by propagating backwards and estimating the close approach with the parent object. Based on this method, the breakup event is predicted to have occurred at approximately 01:42 UTC on 26 March 2016. The Gaussian variation of parameters equations based on the instantaneous orbits at the predicted time of the event are solved to gain additional insight into the on-orbit position of Hitomi at the time of the event and to test an alternate approach of determining the event epoch and location. A conjunction analysis is carried out between Hitomi and all catalogued objects which were in orbit around the estimated time of the anomaly. Several debris objects have close approaches with Hitomi; however, there is no evidence to support the breakup was caused by a catalogued object. Debris from both of the largest fragmentation events—the Iridium 33-Cosmos 2251 conjunction in 2009 and the intentional destruction of Fengyun 1C in 2007—is involved in close approaches with Hitomi indicating the persistent threat these events have caused in subsequent space missions. To quantify the magnitude of a potential conjunction, the fragmentation resulting from a collision with the debris is modelled using the EVOLVE-4 breakup model. The debris characteristics are estimated from two-line element data. This analysis is indicative of the threat to space assets that mission planners face due to the growing debris population. The impact of the actual event to the environment is investigated based on the debris associated with Hitomi which is currently contained in the United States Strategic Command's catalogue. A look at the active missions in the orbital vicinity of Hitomi reveals that the Hubble Space Telescope is among the spacecraft which may be immediately affected by the new debris.[Figure not available: see fulltext.

  16. Beam breakup calculations for the second axis of DARHT

    Energy Technology Data Exchange (ETDEWEB)

    Fawley, William M.; Chen, Y.-J.; Houck, T.L.

    1999-08-20

    The accelerator for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility will produce a 4-kA, 20-MeV, 2-{micro}s output electron beam with a design goal of less than 1000 {pi} mm-mrad normalized transverse emittance and less than 0.5-mm beam centroid motion. In order to meet this goal, the beam transport must have excellent optics and the beam breakup instability (BBU) must be limited in growth. Using a number of simulation codes such as AMOS and BREAKUP, we have modeled the transverse impedances of the DARHT-II accelerator cells and the electron beam response to different transverse excitations such as injector RF noise, magnetic dipole fields arising from the 90-degree bend between the cathode stalk and insulator column, and downstream solenoid alignment errors. The very low Q ({approx}2) predicted for the most important TM dipole modes has prompted us to extend the BREAKUP code to be able to use the dipole wakefields calculated by AMOS in addition to the most usual discrete frequency BBU mode model. We present results for the predicted BBU growth and the empirical sensitivity to various machine parameters.

  17. NAVSPASUR orbital processing for satellite break-up events

    Science.gov (United States)

    Schumacher, Paul W., Jr.

    1991-01-01

    Satellite breakups via explosion or collision can instantly increase the trackable orbiting population by up to several hundred objects, temporarily perturbing the routine space surveillance operations at U.S. Space Command (USSPACWCOM) and the Naval Space Surveillance Center (NAVSPASUR). This paper is a survey of some of the procedures and techniques used by NAVSPASUR to respond to such events. First, the overall data flow at NAVSPASUR is described highlighting the places at which human analysts may intervene with special processing. So-called manual intervention is required in a variety of non-nominal situations, including breakups. Second, a description is given of some of the orbital analysis and other software tools available to NAVSPASUR analysts. These tools were developed in-house over the past thirty years and can be employed in a highly flexible manner. The basic design philosophy for these tools was to implement simple concepts as efficiently as possible and to allow the analyst maximum use of his personal expertise. Finally, several historical breakup scenarios are discussed briefly. These scenarios provide examples of the types of questions that are fairly easy to answer in the present operational environment, as well as examples of questions that are very difficult to answer.

  18. The study of the dp{yields}ppn reaction at 500 MeV of the deuteron energy at ITS Nuclotron

    Energy Technology Data Exchange (ETDEWEB)

    Piyadin, S.M., E-mail: piyadin@jinr.ru [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Janek, M. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Physics Dept, University of Zilina, 010 26 Zilina (Slovakia); Gurchin, Yu.V.; Isupov, A.Yu. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Karachuk, J.-T. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Advanced Research Institute for Electrical Engineering, Bucharest (Romania); Khrenov, A.N.; Krasnov, V.A.; Kurilkin, A.K.; Kurilkin, P.K.; Ladygin, V.P.; Livanov, A.N. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Martinska, G. [P.J.Safarik University, Kosice (Slovakia); Reznikov, S.G. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Semenov, A.K. [Moscow University Radioelectronic and Avtomatic, Dubna, Moscow region (Russian Federation); Terekhin, A.A. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation); Tumanov, A.E. [Moscow University Radioelectronic and Avtomatic, Dubna, Moscow region (Russian Federation); Vasiliev, T.A. [LHEP-JINR, 141-980 Dubna, Moscow region (Russian Federation)

    2011-10-15

    The experiment on dp non-mesonic breakup at Internal Target Station at Nuclotron-M is presented. The first results on the study of the dp-breakup reaction with 500 MeV unpolarized deuteron beam are discussed. Selection procedure of useful events for the dp{yields}ppn reaction with the registration of two protons is shown.

  19. Asymptotic three-particle approach to the Coulomb breakup process {sup 6}Li + {sup 208}Pb → {sup 208}Pb + α + d

    Energy Technology Data Exchange (ETDEWEB)

    Igamov, S. B., E-mail: igamov@inp.uz [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

    2017-03-15

    On the basis of the distorted-wave method, experimental data on the triple-differential cross section for the Coulomb breakup reaction {sup 208}Pb({sup 6}Li, αd){sup 208}Pb are analyzed by employing a correct expression for the final-state {sup 208}Pb–α–d three-particle Coulomb wave function. It is shown that the effect of final-state three-particle Coulomb dynamics can be used to assess the kinematical condition of clean Coulomb breakup processes. New values of the astrophysical S factor for the direct-radiative-capture reaction d(α, γ){sup 6}Li at ultralow energies in the range of 70 ≤ E{sub dα} ≤ 600 keV were extracted from experimental data. The value of S(0) = 1.60 ± 0.17 MeV nb was obtained.

  20. Bag-breakup control of surface drag in hurricanes

    Science.gov (United States)

    Troitskaya, Yuliya; Zilitinkevich, Sergej; Kandaurov, Alexander; Ermakova, Olga; Kozlov, Dmitry; Sergeev, Daniil

    2016-04-01

    Air-sea interaction at extreme winds is of special interest now in connection with the problem of the sea surface drag reduction at the wind speed exceeding 30-35 m/s. This phenomenon predicted by Emanuel (1995) and confirmed by a number of field (e.g., Powell, et al, 2003) and laboratory (Donelan et al, 2004) experiments still waits its physical explanation. Several papers attributed the drag reduction to spume droplets - spray turning off the crests of breaking waves (e.g., Kudryavtsev, Makin, 2011, Bao, et al, 2011). The fluxes associated with the spray are determined by the rate of droplet production at the surface quantified by the sea spray generation function (SSGF), defined as the number of spray particles of radius r produced from the unit area of water surface in unit time. However, the mechanism of spume droplets' formation is unknown and empirical estimates of SSGF varied over six orders of magnitude; therefore, the production rate of large sea spray droplets is not adequately described and there are significant uncertainties in estimations of exchange processes in hurricanes. Herewith, it is unknown what is air-sea interface and how water is fragmented to spray at hurricane wind. Using high-speed video, we observed mechanisms of production of spume droplets at strong winds by high-speed video filming, investigated statistics and compared their efficiency. Experiments showed, that the generation of the spume droplets near the wave crest is caused by the following events: bursting of submerged bubbles, generation and breakup of "projections" and "bag breakup". Statistical analysis of results of these experiments showed that the main mechanism of spray-generation is attributed to "bag-breakup mechanism", namely, inflating and consequent blowing of short-lived, sail-like pieces of the water-surface film. Using high-speed video, we show that at hurricane winds the main mechanism of spray production is attributed to "bag-breakup", namely, inflating and

  1. Squeezing bio-capsules into a constriction: deformation till break-up.

    Science.gov (United States)

    Le Goff, Anne; Kaoui, Badr; Kurzawa, Gaetan; Haszon, Boglárka; Salsac, Anne-Virginie

    2017-10-25

    We study experimentally the deformation and break-up of liquid-filled capsules trapped at an axisymmetric step constriction, and subjected to increasing pressure drops. We considered biological (trout fish eggs) and bioartificial (made of ovalbumin and alginate) ones, with the objective to characterize the transition to break-up. We find that both capsule populations behave as a brittle material. They do not exhibit any plastic deformation prior to break-up. Moreover critical pressure drop exhibits a stochastic behavior as known for the fracture of disordered media. The break-up probability follows a three-parameter Weibull distribution, from which one can deduce the capsule rupture characteristics.

  2. Breakup conditions of projectile spectators from dynamical observables

    Science.gov (United States)

    Begemann-Blaich, M.; Lindenstruth, V.; Pochodzalla, J.; Adloff, J. C.; Bouissou, P.; Hubele, J.; Imme, G.; Iori, I.; Kreutz, P.; Kunde, G. J.; Leray, S.; Liu, Z.; Lynen, U.; Meijer, R. J.; Milkau, U.; Moroni, A.; Müller, W. F.; Ngô, C.; Ogilvie, C. A.; Raciti, G.; Rudolf, G.; Sann, H.; Schnittker, M.; Schüttauf, A.; Seidel, W.; Stuttge, L.; Trautmann, W.; Tucholski, A.

    1998-09-01

    Momenta and masses of heavy projectile fragments (Z>=8), produced in collisions of 197Au with C, Al, Cu, and Pb targets at E/A=600 MeV, were determined with the ALADIN magnetic spectrometer at SIS. Using this information, an analysis of kinematic correlations between the two and three heaviest projectile fragments in their rest frame was performed. The sensitivity of these correlations to the conditions at breakup was verified within the schematic SOS model. For a quantitative investigation, the data were compared to calculations with statistical multifragmentation models and to classical three-body calculations. With classical trajectory calculations, where the charges and masses of the fragments are taken from a Monte Carlo sampling of the experimental events, the dynamical observables can be reproduced. The deduced breakup parameters, however, differ considerably from those assumed in the statistical multifragmentation models which describe the charge correlations. If, on the other hand, the analysis of kinematic and charge correlations is performed for events with two and three heavy fragments produced by statistical multifragmentation codes, good agreement with the data is found with the exception that the fluctuation widths of the intrinsic fragment energies are significantly underestimated. A new version of the multifragmentation code MCFRAG was therefore used to investigate the potential role of angular momentum at the breakup stage. If a mean angular momentum of 0.75ħ/nucleon is added to the system, the energy fluctuations can be reproduced, but at the same time the charge partitions are modified and deviate from the data.

  3. Lattice Boltzmann modeling and simulation of liquid jet breakup

    Science.gov (United States)

    Saito, Shimpei; Abe, Yutaka; Koyama, Kazuya

    2017-07-01

    A three-dimensional color-fluid lattice Boltzmann model for immiscible two-phase flows is developed in the framework of a three-dimensional 27-velocity (D3Q27) lattice. The collision operator comprises the D3Q27 versions of three suboperators: a multiple-relaxation-time (MRT) collision operator, a generalized Liu-Valocchi-Kang perturbation operator, and a Latva-Kokko-Rothman recoloring operator. A D3Q27 version of an enhanced equilibrium distribution function is also incorporated into this model to improve the Galilean invariance. Three types of numerical tests, namely, a static droplet, an oscillating droplet, and the Rayleigh-Taylor instability, show a good agreement with analytical solutions and numerical simulations. Following these numerical tests, this model is applied to liquid-jet-breakup simulations. The simulation conditions are matched to the conditions of the previous experiments. In this case, numerical stability is maintained throughout the simulation, although the kinematic viscosity for the continuous phase is set as low as 1.8 ×10-4 , in which case the corresponding Reynolds number is 3.4 ×103 ; the developed lattice Boltzmann model based on the D3Q27 lattice enables us to perform the simulation with parameters directly matched to the experiments. The jet's liquid column transitions from an asymmetrical to an axisymmetrical shape, and entrainment occurs from the side of the jet. The measured time history of the jet's leading-edge position shows a good agreement with the experiments. Finally, the reproducibility of the regime map for liquid-liquid systems is assessed. The present lattice Boltzmann simulations well reproduce the characteristics of predicted regimes, including varicose breakup, sinuous breakup, and atomization.

  4. Breakup conditions of projectile spectators from dynamical observables

    Energy Technology Data Exchange (ETDEWEB)

    Begemann-Blaich, M.; Lindenstruth, V.; Pochodzalla, J. [and others

    1998-03-01

    Momenta and masses of heavy projectile fragments (Z {>=} 8), produced in collisions of {sup 197}Au with C, Al, Cu and Pb targets at E/A=600 MeV, were determined with the ALADIN magnetic spectrometer at SIS. Using these informations, an analysis of kinematic correlations between the two and three heaviest projectile fragments in their rest frame was performed. The sensitivity of these correlations to the conditions at breakup was verified within the schematic SOS-model. For a quantitative investigation, the data were compared to calculations with statistical multifragmentation models and to classical three-body calculations. With classical trajectory calculations, where the charges and masses of the fragments are taken from a Monte Carlo sampling of the experimental events, the dynamical observables can be reproduced. The deduced breakup parameters, however, differ considerably from those assumed in the statistical multifragmentation models which describe the charge correlations. If, on the other hand, the analysis of kinematic and charge correlations is performed for events with two and three heavy fragments produced by statistical multifragmentation codes, a good agreement with the data is found with the exception that the fluctuation widths of the intrinsic fragment energies are significantly underestimated. A new version of the multifragmentation code MCFRAG was therefore used to investigate the potential role of angular momentum at the breakup stage. If a mean angular momentum of 0.75 {Dirac_h}/nucleon is added to the system, the energy fluctuations can be reproduced, but at the same time the charge partitions are modified and deviate from the data. (orig.)

  5. Polyphase Rifting and Breakup of the Central Mozambique Margin

    Science.gov (United States)

    Senkans, Andrew; Leroy, Sylvie; d'Acremont, Elia; Castilla, Raymi

    2017-04-01

    The breakup of the Gondwana supercontinent resulted in the formation of the Central Mozambique passive margin as Africa and Antarctica were separated during the mid-Jurassic period. The identification of magnetic anomalies in the Mozambique Basin and Riiser Larsen Sea means that post-oceanisation plate kinematics are well-constrained. Unresolved questions remain, however, regarding the initial fit, continental breakup process, and the first relative movements of Africa and Antarctica. This study uses high quality multi-channel seismic reflection profiles in an effort to identify the major crustal domains in the Angoche and Beira regions of the Central Mozambique margin. This work is part of the integrated pluri-disciplinary PAMELA project*. Our results show that the Central Mozambique passive margin is characterised by intense but localised magmatic activity, evidenced by the existence of seaward dipping reflectors (SDR) in the Angoche region, as well as magmatic sills and volcanoclastic material which mark the Beira High. The Angoche region is defined by a faulted upper-continental crust, with the possible exhumation of lower crustal material forming an extended ocean-continent transition (OCT). The profiles studied across the Beira high reveal an offshore continental fragment, which is overlain by a pre-rift sedimentary unit likely to belong to the Karoo Group. Faulting of the crust and overlying sedimentary unit reveals that the Beira High has recorded several phases of deformation. The combination of our seismic interpretation with existing geophysical and geological results have allowed us to propose a breakup model which supports the idea that the Central Mozambique margin was affected by polyphase rifting. The analysis of both along-dip and along-strike profiles shows that the Beira High initially experienced extension in a direction approximately parallel to the Mozambique coastline onshore of the Beira High. Our results suggest that the Beira High results

  6. Study of Liquid Breakup Process in Solid Rocket Motor Nozzle

    Science.gov (United States)

    2016-02-16

    Journal Article 3. DATES COVERED (From - To) 16 June 2015 – 31 July 2015 4. TITLE AND SUBTITLE Study of Liquid Breakup Process in Solid Rocket Motor... Rockets , Volume 52 Issue 4 July 2015 (AIAA 2015-1605) PA Case Number: #15348; Clearance Date: 6/26/2015 ©2015 AIAA The U.S. Government is joint author...of the work and has the right to use, modify, reproduce, release, perform, display, or 14. ABSTRACT In a solid rocket motor (SRM), when the

  7. Break-up dynamics of fluctuating liquid threads.

    Science.gov (United States)

    Petit, Julien; Rivière, David; Kellay, Hamid; Delville, Jean-Pierre

    2012-11-06

    The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from a faucet or a capillary, follows different rules and dynamic scaling laws depending on the importance of inertia, viscous stresses, or capillary forces. If now the thinning neck reaches dimensions comparable to the thermally excited interfacial fluctuations, as for nanojet break-up or the fragmentation of thermally annealed nanowires, these fluctuations should play a dominant role according to recent theory and observations. Using near-critical interfaces, we here fully characterize the universal dynamics of this thermal fluctuation-dominated regime and demonstrate that the cross-over from the classical two-fluid pinch-off scenario of a liquid thread to the fluctuation-dominated regime occurs at a well-defined neck radius proportional to the thermal length scale. Investigating satellite drop formation, we also show that at the level of the cross-over between these two regimes it is more probable to produce monodisperse droplets because fluctuation-dominated pinch-off may allow the unique situation where satellite drop formation can be inhibited. Nonetheless, the interplay between the evolution of the neck profiles from the classical to the fluctuation-dominated regime and the satellites' production remains to be clarified.

  8. Break-up of New Orleans Households after Hurricane Katrina.

    Science.gov (United States)

    Rendall, Michael S

    2011-06-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household break-up due to Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads and non-household heads (N = 242), traced just over a year later, with a matched sample from a nationally representative survey over an equivalent period. One in three among all adult non-household heads, and one in two among adult children of household heads, had separated from the household head 1 year post-Katrina. These rates were, respectively, 2.2 and 2.7 times higher than national rates. A 50% higher prevalence of adult children living with parents in pre-Katrina New Orleans than nationally increased the hurricane's impact on household break-up. Attention to living arrangements as a dimension of social vulnerability in disaster recovery is suggested.

  9. Numerical Simulation of Thin Film Breakup on Nonwettable Surfaces

    Science.gov (United States)

    Suzzi, N.; Croce, G.

    2017-01-01

    When a continuous film flows on a nonwettable substrate surface, it may break up, with the consequent formation of a dry-patch. The actual shape of the resulting water layer is of great interest in several engineering applications, from in-flight icing simulation to finned dehumidifier behavior modeling. Here, a 2D numerical solver for the prediction of film flow behavior is presented. The effect of the contact line is introduced via the disjoining pressure terms, and both gravity and shear are included in the formulation. The code is validated with literature experimental data for the case of a stationary dry-patch on an inclined plane. Detailed numerical results are compared with literature simplified model prediction. Numerical simulation are then performed in order to predict the threshold value of the film thickness allowing for film breakup and to analyze the dependence of the dynamic contact angle on film velocity and position along the contact line. Those informations will be useful in order to efficiently predict more complex configuration involving multiple breakups on arbitrarily curved substrate surfaces (as those involved in in-flight icing phenomena on aircraft).

  10. Time-varying droplet configuration determines break-up probability of drops within a concentrated emulsion

    Science.gov (United States)

    Khor, Jian Wei; Kim, Minkyu; Schütz, Simon S.; Schneider, Tobias M.; Tang, Sindy K. Y.

    2017-09-01

    This paper aims to identify the origin of the probability of break-up of drops within a concentrated emulsion flowing as a 2D monolayer through a tapered microchannel into a constriction. Although the concentrated emulsion is complex involving many-body interactions, all break-up events occur between two drops pinching each other as they enter the constriction under the conditions tested. Whether break-up occurs or not depends strongly on the relative position between the two drops at the entrance of the constriction. There exist a critical offset between the initial positions of the two drops below which break-up always occurs and another critical offset above which no break-up occurs. In between these two critical offsets, there is a narrow bistable region where both break-up and non-break-up events are observed. For a flowing concentrated emulsion, the relative position between two droplets entering the constriction varies stochastically. The frequency of occurrence of drop pairs having specific offsets, together with the critical offset values for break-up, determines the break-up probability in the flowing emulsion.

  11. Restructuring and Break-Up of Two-Dimensional Aggregates in Shear Flow

    NARCIS (Netherlands)

    Vassileva, Nikolina D.; van den Ende, Henricus T.M.; Mugele, Friedrich Gunther; Mellema, J.

    2006-01-01

    We consider single two-dimensional aggregates, containing glass particles, placed at a water/air interface. We have investigated the critical shear rate for break-up of aggregates with different sizes in a simple shear flow. All aggregates break-up nearly at the same shear rate (1.8 ± 0.2 s-1)

  12. Modelling wave-induced sea ice break-up in the marginal ice zone

    Science.gov (United States)

    Montiel, F.; Squire, V. A.

    2017-10-01

    A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

  13. Amphiphilic nanoparticles suppress droplet break-up in a concentrated emulsion flowing through a narrow constriction.

    Science.gov (United States)

    Gai, Ya; Kim, Minkyu; Pan, Ming; Tang, Sindy K Y

    2017-05-01

    This paper describes the break-up behavior of a concentrated emulsion comprising drops stabilized by amphiphilic silica nanoparticles flowing in a tapered microchannel. Such geometry is often used in serial droplet interrogation and sorting processes in droplet microfluidics applications. When exposed to high viscous stresses, drops can undergo break-up and compromise their physical integrity. As these drops are used as micro-reactors, such compromise leads to a loss in the accuracy of droplet-based assays. Here, we show droplet break-up is suppressed by replacing the fluoro-surfactant similar to the one commonly used in current droplet microfluidics applications with amphiphilic nanoparticles as droplet stabilizer. We identify parameters that influence the break-up of these drops and demonstrate that break-up probability increases with increasing capillary number and confinement, decreasing nanoparticle size, and is insensitive to viscosity ratio within the range tested. Practically, our results reveal two key advantages of nanoparticles with direct applications to droplet microfluidics. First, replacing surfactants with nanoparticles suppresses break-up and increases the throughput of the serial interrogation process to 3 times higher than that in surfactant system under similar flow conditions. Second, the insensitivity of break-up to droplet viscosity makes it possible to process samples having different composition and viscosities without having to change the channel and droplet geometry in order to maintain the same degree of break-up and corresponding assay accuracy.

  14. Break-up of a non-Newtonian jet injected downwards in a ...

    Indian Academy of Sciences (India)

    CFD analysis of the temporal variation of interface and jet length ( L j ) is done to propose different types of jet breakup regimes. At smaller, intermediate and larger values of V a v , i , the regimes found are periodic uniform drop (P-UD), quasi-periodic non-uniform drop (QP-NUD) and no breakup (NB) regimes for a shear ...

  15. Stability of Monetary Unions : Lessons from the Break-Up of Czechoslovakia

    NARCIS (Netherlands)

    Fidrmuc, J.; Horváth, J.

    1998-01-01

    In 1993, Czechoslovakia experienced a two-fold break-up: On January 1st, the country disintegrated as a political union, while preserving an economic and monetary union. Then, the Czech-Slovak monetary union collapsed on February 8th. We analyze the economic background of the two break-ups, and

  16. Modelling wave-induced sea ice break-up in the marginal ice zone.

    Science.gov (United States)

    Montiel, F; Squire, V A

    2017-10-01

    A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

  17. The breakup of levitating water drops observed with a high speed camera

    Directory of Open Access Journals (Sweden)

    C. Emersic

    2011-10-01

    Full Text Available Collision-induced water drop breakup in a vertical wind tunnel was observed using a high speed camera for interactions between larger drop sizes (up to 7 mm diameter than have previously been experimentally observed. Three distinct collisional breakup types were observed and the drop size distributions from each were analysed for comparison with predictions of fragment distributions from larger drops by two sets of established breakup parameterisations. The observations showed some similarities with both parameterisations but also some marked differences for the breakup types that could be compared, particularly for fragments 1 mm and smaller. Modifications to the parameterisations are suggested and examined. Presented is also currently the largest dataset of bag breakup distributions observed. Differences between this and other experimental research studies and modelling parameterisations, and the associated implications for interpreting results are discussed. Additionally, the stochastic coalescence and breakup equation was solved computationally using a breakup parameterisation, and the evolving drop-size distribution for a range of initial conditions was examined. Initial cloud liquid water content was found to have the greatest influence on the resulting distribution, whereas initial drop number was found to have relatively little influence. This may have implications when considering the effect of aerosol on cloud evolution, raindrop formation and resulting drop size distributions. Calculations presented show that, using an ideal initial cloud drop-size distribution, ~1–3% of the total fragments are contributed from collisional breakup between drops of 4 and 6 mm.

  18. Measurement Of Axial Spin Observables In The Polarized Deuteron-polarized Proton Breakup At 270mev

    CERN Document Server

    Whitaker, T J

    2004-01-01

    We report the measurement of “axial” spin observables in the dp breakup reaction at 270MeV. These measurements were made using a stored polarized “cooled” deuteron beam and a polarized internal hydrogen target at the Indiana University Cyclotron Facility (IUCF). Given our beam and target spin-alignment directions we were able to measure the axial spin observables Apz , Cy,x − Cx,y, and Czz,z. Axial spin observables are the subset of observables which are antisymmetric under the parity operation and are thus forbidden in reactions where the outgoing momenta are coplanar with the beam momentum. It has been argued that axial observables may be more sensitive to a three-body force than other spin observables. We compare our measurements to theoretical predictions based on the CD- Bonn nucleon-nucleon potential and the TM ′ three-nucleon force, using a new method to correctly take into account the experimental constraints. The only previous measurement...

  19. Distress Severity Following a Romantic Breakup is Associated with Positive Relationship Memories among Emerging Adults

    DEFF Research Database (Denmark)

    del Palacio Gonzalez, Adriana; Clark, David; O'Sullivan, Lucia

    2017-01-01

    Romantic relationship loss is associated with significant psychological distress for emerging adults. Intrusive memories of stressful events are typically associated with symptom severity; however, whether spontaneous positive memories of a relationship breakup may also be related to psychological...... symptoms has received little attention. We examined links between breakup-specific distress, depressive symptoms, and relationship memories of different valence. Ninety-one emerging adults (Mage = 20.13) who had experienced a recent romantic breakup recorded the frequency of positive and negative...... spontaneous relationship memories in a four-day online memory diary. Control memories were also recorded. Positive memories were specifically related to breakup distress, whereas negative memories were related to both breakup distress and depression. No such associations were found for the control memories...

  20. Classical simulations of heavy-ion fusion reactions and weakly ...

    Indian Academy of Sciences (India)

    This model is extended to simulate heavy-ion reactions such as 6Li + 209Bi involving the weakly-bound projectile considered as a weakly-bound cluster of deuteron and 4He nuclei, thus, simulating a 3-body system in 3S-CMD model. All the essential features of breakup reactions, such as complete fusion, incomplete fusion ...

  1. N-d scattering above the deuteron breakup threshold

    Energy Technology Data Exchange (ETDEWEB)

    Kievsky, A.; Viviani, M.; Rosati, S. [Istituto Nazionale di Fisica Nucleare, Piazza Torricelli 2, 56100 Pisa (Italy)]|[Dipartimento di Fisica, Universita di Pisa, Piazza Torricelli 2, 56100 Pisa (Italy)

    1997-12-01

    The complex Kohn variational principle and the (correlated) hyperspherical harmonics technique are applied to study N-d scattering above the deuteron breakup threshold. The configuration with three outgoing nucleons is explicitly taken into account by solving a set of differential equations with outgoing boundary conditions. A convenient procedure is used to obtain the correct boundary conditions at values of the hyperradius of {approx}100 fm. The inclusion of the Coulomb potential is straightforward and does not give additional difficulties. Numerical results have been obtained for a simple s-wave central potential. They are in nice agreement with the benchmarks produced by different groups using the Faddeev technique. Comparisons are also done with experimental elastic N-d cross section at several energies. {copyright} {ital 1997} {ital The American Physical Society}

  2. Stability of volcanic ash aggregates and break-up processes.

    Science.gov (United States)

    Mueller, Sebastian B; Kueppers, Ulrich; Ametsbichler, Jonathan; Cimarelli, Corrado; Merrison, Jonathan P; Poret, Matthieu; Wadsworth, Fabian B; Dingwell, Donald B

    2017-08-07

    Numerical modeling of ash plume dispersal is an important tool for forecasting and mitigating potential hazards from volcanic ash erupted during explosive volcanism. Recent tephra dispersal models have been expanded to account for dynamic ash aggregation processes. However, there are very few studies on rates of disaggregation during transport. It follows that current models regard ash aggregation as irrevocable and may therefore overestimate aggregation-enhanced sedimentation. In this experimental study, we use industrial granulation techniques to artificially produce aggregates. We subject these to impact tests and evaluate their resistance to break-up processes. We find a dependence of aggregate stability on primary particle size distribution and solid particle binder concentration. We posit that our findings could be combined with eruption source parameters and implemented in future tephra dispersal models.

  3. Gondwanan break-up: legacies of a lost world?

    Science.gov (United States)

    Upchurch, Paul

    2008-04-01

    Fierce debate surrounds the history of organisms in the southern hemisphere; did Gondwanan break-up produce ocean barriers that imposed distribution patterns on phylogenies (vicariance)? Or have organisms modified their distributions through trans-oceanic dispersal? Recent advances in biogeographical theory suggest that the current focus on vicariance versus dispersal is too narrow because it ignores 'geodispersal' (i.e. expansion of species into areas when geographical barriers disappear), extinction and sampling errors. Geodispersal produces multiple, conflicting vicariance patterns, and extinction and sampling errors destroy vicariance patterns. This perspective suggests that it is more difficult to detect vicariance than trans-oceanic dispersal and that specialized methods must be applied if an unbiased understanding of southern hemisphere biogeography is to be achieved.

  4. Studying the field induced breakup of acoustically levitated drops

    Science.gov (United States)

    Warschat, C.; Riedel, J.

    2017-10-01

    Coulomb fission of charged droplets (The terms drop and droplet are often used synonymous. Throughout this manuscript, to avoid confusion, the terms drop and droplet will be used for liquid spheres with radii in the millimeter range and the micrometer range, respectively. In our experiments, the first correspond to the parent drop while the latter describes the ejected progeny droplets.) is a well-studied natural phenomenon. Controlled droplet fission is already successfully employed in several technological applications. Still, since the occurring surface rupture relies on the exact understanding and description of the liquid gas boundary, some details are still under debate. Most empirical systematic studies observe falling micrometer droplets passing through the electric field inside a plate capacitor. This approach, although easily applicable and reliable, limits the experimental degrees of freedom regarding the observable time and the maximum size of the drops and can only be performed in consecutive individual observations of different subsequent drops. Here we present a novel setup to study the field induced breakup of acoustically levitated drops. The design does not bear any restrictions towards the temporal window of observation, and allows handling of drops of a tunable radius ranging from 10 μm to several millimeters and a real-time monitoring of one single drop. Our comprehensive study includes a time resolved visual inspection, laser shadowgraphy, laser induced fluorescence imaging, and ambient mass spectrometric interrogation of the nascent Taylor cone. The results shown for a millimeter sized drop, previously inaccessible for Coulomb fission experiments, are mostly comparable with previous results for smaller drops. The major difference is the time scale and the threshold potential of the drop rupture. Both values, however, resemble theoretically extrapolations to the larger radius. The technique allows for a systematic study of breakup behavior of

  5. Parental break-ups and stress: roles of age & family structure in 44 509 pre-adolescent children.

    Science.gov (United States)

    Dissing, Agnete S; Dich, Nadya; Andersen, Anne-Marie Nybo; Lund, Rikke; Rod, Naja H

    2017-10-01

    Parental break-up is wide spread, and the effects of parental break-up on children's well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre-adolescent children with a specific focus on age at break-up and post-breakup family arrangements. We used data from the Danish National Birth Cohort. Participants included 44 509 children followed from birth to age 11. Stress was self-reported by children at age 11, when the children also reported on parental break-up and post break-up family arrangements. Twenty-one percent of the children had experienced a parental break-up at age 11, and those who had experienced parental break-up showed a higher risk of stress (OR:1.72, 95%CI:1.55;1.91) regardless of the child's age at break-up. Children living in a new family with stepparents (OR = 1.63, 95%CI:1.38;1.92), or shared between the parents (OR = 1.48, 95%CI:1.26;1.75) reported higher stress than children of intact families. Single parent families reported markedly higher stress levels than children in intact families (OR = 2.18, 95%CI:1.90;2.50) and all other family types. Children who were satisfied with their living arrangements post-break-up reported the same stress level as children living in intact families (OR = 1.01, 95%CI:0.86;1.18). Children who experience parental break-up have higher stress levels, also many years after the break-up, and those living in a single parent household post break-up seem to be most vulnerable. Living arrangements post-breakup should be further investigated as a potential protective factor.

  6. Considerations and calculations on the breakup of jets and drops of melt related to premixing

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, M.; Berg, E. von; Buck, M. [Inst. fuer Kernenergetik und Energiesysteme (IKE), Univ. of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

    1998-01-01

    Various descriptions of jet and drop breakup are applied in premixing codes, presently. The main task is to check these descriptions over a wide range of conditions in order to assure extrapolation capabilities for the codes. Jet breakup under non-boiling conditions is relatively well described by IKEJET, based on Conte/Miles (CM) instability description and a relatively detailed stripping model, in contrast to using Kelvin/Helmholtz (KH) theory. Remaining open questions are elaborated. Especially, thick jet behavior with dominance of stripping even at small relative velocities must be distinguished from thin jets with coarse breakup. The application of IKEJET to cases with jet breakup under strong film boiling yielded significantly too little fragmentation. As a possible explanation line, multiphase effects on the wave growth and stripping are considered, due to entrainment of melt and water. Parametric checking calculations are performed with a strongly simplified approach for PREMIX and FARO experiments in order to reveal main effects and the possible physical explanation features as a basis for extended modelling. The results indicate that jet breakup may be essentially sufficient to explain the experimental behavior. Rather coalescence than further drop breakup may be expected. This is also indicated by calculations with IKE drop breakup models. (author)

  7. Investigation of correlations in the breakup of He{sup 8}; Etude des correlations dans la dissociation de l'He{sup 8}

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, B

    2007-11-15

    Correlations in light neutron-rich nuclei are of considerable importance in understanding their structure. In this context the breakup of He{sup 8} into He{sup 6} + 2n has been investigated at 15 MeV/nucleon. The measurements were undertaken using a setup composed of two detector arrays: CHARISSA to detect the charged fragments and DEMON to detect the neutrons. The interpretation of the results was facilitated using a Monte Carlo simulation which was developed to take into account the correlations, the reaction and the experimental setup. Two techniques were used to study the correlations in the breakup of He{sup 8}. The first, intensity interferometry, provides, via the construction of the neutron-neutron correlation function, for a first estimate of the source size and thus the average separation between the neutrons. The second, using Dalitz plots, allows both the neutron-neutron and core-neutron correlations to be probed. Here, sequential decay via the ground state resonance of He{sup 7} and has been found to dominate the dissociation of He{sup 8}. The spatial and temporal characteristics of the breakup of He{sup 8} have thus been deduced and a root-mean-square separation between the two valence neutrons in the continuum states was estimated to be (7.3 {+-} 0.6) fm with a time delay between their emission of (1000 {+-} 300) fm/c. (author)

  8. Facing a breakup: Electromyographic responses moderate self-concept recovery following a romantic separation

    Science.gov (United States)

    MASON, ASHLEY E.; LAW, RITA W.; BRYAN, AMANDA E. B.; PORTLEY, ROBERT M.; SBARRA, DAVID A.

    2015-01-01

    Romantic breakups arouse fundamental questions about the self: Who am I without my partner? This study examined self-concept reorganization and psychological well-being over an 8-week period in the months following a breakup. Multilevel analyses revealed that poorer self-concept recovery preceded poorer well-being and was associated with love for an ex-partner, suggesting that failure to redefine the self contributes to post-breakup distress. Psychophysiological data revealed that greater activity in the corrugator supercilia facial muscle while thinking about an ex-partner predicted poorer self-concept recovery and strengthened the negative association between love for an ex-partner and self-concept recovery. Thus, the interaction between self-report and psychophysiological data provided information about the importance of self-concept recovery to post-breakup adjustment not tapped by either method alone. PMID:26167126

  9. Distress Severity Following a Romantic Breakup is Associated with Positive Relationship Memories among Emerging Adults

    DEFF Research Database (Denmark)

    del Palacio Gonzalez, Adriana; Clark, David; O'Sullivan, Lucia

    2017-01-01

    Romantic relationship loss is associated with significant psychological distress for emerging adults. Intrusive memories of stressful events are typically associated with symptom severity; however, whether spontaneous positive memories of a relationship breakup may also be related to psychological...... symptoms has received little attention. We examined links between breakup-specific distress, depressive symptoms, and relationship memories of different valence. Ninety-one emerging adults (Mage = 20.13) who had experienced a recent romantic breakup recorded the frequency of positive and negative....... The results suggest that experiences of positive memories are critical for understanding the degree of distress a young person may experience following a breakup. Possible explanations for these findings and similarities with the grief and bereavement literature are discussed....

  10. Break-up of droplets in a concentrated emulsion flowing through a narrow constriction.

    Science.gov (United States)

    Rosenfeld, Liat; Fan, Lin; Chen, Yunhan; Swoboda, Ryan; Tang, Sindy K Y

    2014-01-21

    This paper describes the break-up of droplets in a concentrated emulsion during its flow as a 2D monolayer in a microchannel consisting of a narrow constriction. Analysis of the behavior of a large number of drops (N > 4000) shows that the number of break-ups increases with increasing flow rate, entrance angle to the constriction, and size of the drops relative to the width of the constriction. As single drops do not break at the highest flow rate used in the system, break-ups arise primarily from droplet-droplet interactions. Analysis of droplet properties at a high temporal resolution of 10 microseconds makes it possible to relate droplet deformation with droplet break-up probability. Similar to previous studies on single drops, no break-up is observed below a set of critical flow rates and droplet deformations. Unlike previous studies, however, not all drops undergo break-up above the critical values. Instead, the probability of droplet break-up increases with flow rate and the deformation of the drops. The probabilistic nature of the break-up process arises from the stochastic variations in the packing configuration of the drops as they enter the constriction. Local break-up dynamics involves two primary drops. A close look at the interactions between the pair of drops reveals that the competing time scales of droplet rearrangement relative to the relaxation of the opposing drop govern whether break-up occurs or not. Practically, these results can be used to calculate the maximum throughput of the serial interrogation process often employed in droplet microfluidics. For 40 pL-drops, the highest throughput with less than 1% droplet break-up was measured to be approximately 7000 drops per second. In addition, the results presented are useful for understanding the behavior of concentrated emulsions in applications such as mobility control in enhanced oil recovery, and for extrapolating critical parameters such as injection rates to ensure the stability of the

  11. Decrease in oceanic crustal thickness since the breakup of Pangaea

    Science.gov (United States)

    van Avendonk, Harm J. A.; Davis, Joshua K.; Harding, Jennifer L.; Lawver, Lawrence A.

    2017-01-01

    Earth's mantle has cooled by 6-11 °C every 100 million years since the Archaean, 2.5 billion years ago. In more recent times, the surface heat loss that led to this temperature drop may have been enhanced by plate-tectonic processes, such as continental breakup, the continuous creation of oceanic lithosphere at mid-ocean ridges and subduction at deep-sea trenches. Here we use a compilation of marine seismic refraction data from ocean basins globally to analyse changes in the thickness of oceanic crust over time. We find that oceanic crust formed in the mid-Jurassic, about 170 million years ago, is 1.7 km thicker on average than crust produced along the present-day mid-ocean ridge system. If a higher mantle temperature is the cause of thicker Jurassic ocean crust, the upper mantle may have cooled by 15-20 °C per 100 million years over this time period. The difference between this and the long-term mantle cooling rate indeed suggests that modern plate tectonics coincide with greater mantle heat loss. We also find that the increase of ocean crustal thickness with plate age is stronger in the Indian and Atlantic oceans compared with the Pacific Ocean. This observation supports the idea that upper mantle temperature in the Jurassic was higher in the wake of the fragmented supercontinent Pangaea due to the effect of continental insulation.

  12. Break-up and Coalescence in Liquid/Liquid Flows

    Science.gov (United States)

    Longmire, Ellen K.

    2004-11-01

    Break-up and coalescence transitions in mixtures of oil- and water-based fluids are investigated experimentally with the goal of understanding the underlying dynamics and of eventually developing accurate numerical models for practical applications such as transport, mixing, and separation of petroleum, chemical, and waste streams. Several geometries are examined: natural and periodically forced jets flowing into and breaking up in an ambient, drops impacting and eventually coalescing at a quiescent interface, and coalescing drop pairs. Refractive index matching and laser induced fluorescence are employed to obtain clear images of the interfaces and interior volumes within each flow. Real-time flow sequences of planar fields are acquired using a high-frequency laser and camera system, and the resulting images are analyzed to determine interfacial behavior as well as two- and three-component velocity fields. In the jet flow, the effects of fluid viscosity ratio, Reynolds number, Strouhal number, and Ohnesorge number on the flow dynamics will be discussed. In the coalescing flows, the effects of viscosity ratio, impact Weber number and offset distance will be discussed. Finally, some of the experimental results will be compared with the results of numerical simulations incorporating transition models and adaptive grids.

  13. Style of rifting and the stages of Pangea breakup

    Science.gov (United States)

    Frizon de Lamotte, Dominique; Fourdan, Brendan; Leleu, Sophie; Leparmentier, François; de Clarens, Philippe

    2015-05-01

    Pangea results from the progressive amalgamation of continental blocks achieved at 320 Ma. Assuming that the ancient concept of "active" versus "passive" rifting remains pertinent as end-members of more complex processes, we show that the progressive Pangea breakup occurred through a succession of rifting episodes characterized by different tectonic evolutions. A first episode of passive continental rifting during the Upper Carboniferous and Permian led to the formation of the Neo-Tethys Ocean. Then at the beginning of Triassic times, two short episodes of active rifting associated to the Siberian and Emeishan large igneous provinces (LIPs) failed. The true disintegration of Pangea resulted from (1) a Triassic passive rifting leading to the emplacement of the central Atlantic magmatic province (200 Ma) LIP and the subsequent opening of the central Atlantic Ocean during the lowermost Jurassic and from (2) a Lower Jurassic active rifting triggered by the Karoo-Ferrar LIP (183 Ma), which led to the opening of the West Indian Ocean. The same sequence of passive then active rifting is observed during the Lower Cretaceous with, in between, the Parana-Etendeka LIP at 135 Ma. We show that the relationships between the style of rifts and their breakdown or with the type of resulting margins (as magma poor or magma dominated) are not straightforward. Finally, we discuss the respective role of mantle global warming promoted by continental agglomeration and mantle plumes in the weakening of the continental lithosphere and their roles as rifting triggers.

  14. Cheating, breakup, and divorce: is Facebook use to blame?

    Science.gov (United States)

    Clayton, Russell B; Nagurney, Alexander; Smith, Jessica R

    2013-10-01

    The purpose of the present study was to investigate the relationship between using the social networking site known as Facebook and negative interpersonal relationship outcomes. A survey of 205 Facebook users aged 18-82 was conducted using a 16-question online survey to examine whether high levels of Facebook use predicted negative relationship outcomes (breakup/divorce, emotional cheating, and physical cheating). It was hypothesized that those with higher levels of Facebook use would demonstrate more negative relationship outcomes than those with lower use. The study then examined whether these relationships were mediated by Facebook-related conflict. Furthermore, the researchers examined length of relationship as a moderator variable in the aforementioned model. The results indicate that a high level of Facebook usage is associated with negative relationship outcomes, and that these relationships are indeed mediated by Facebook-related conflict. This series of relationships only holds for those who are, or have been, in relatively newer relationships of 3 years or less. The current study adds to the growing body of literature investigating Internet use and relationship outcomes, and may be a precursor to further research investigating whether Facebook use attributes to the divorce rate, emotional cheating, and physical cheating.

  15. Calculation of A (x) for the Proton-Deuteron Breakup Reaction at 135 MeV

    NARCIS (Netherlands)

    Eslami-Kalantari, M.; Mehmandoost-Khajeh-Dad, A. A.; Shafaei, M. A.; Amir-Ahmadi, H. R.; Biegun, A.; Gasparic, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Moeini, H.; Ramazani Moghaddam Arani, Ahmad; Shende, S. V.; Stephan, E.; Sworst, R.

    Observables in proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects (3NF). Several facilities in the world, including Kernfysisch Versneller Instituut (KVI), allow a detailed study a few-nucleon interaction below the pion-production

  16. Subducting Plate Breakup by Plume-Lithosphere Interaction

    Science.gov (United States)

    Koptev, A.; Gerya, T.; Jolivet, L.; Leroy, S. D.

    2016-12-01

    We use a 3D high-resolution thermo-mechanical modeling to investigate the impact of active mantle plume on a subducting lithospheric plate. Initial model setup consists of an overriding continental lithosphere and subducting lithospheric plate including oceanic and continental lithosphere. A mantle plume thermal anomaly has been initially seeded at the bottom of the model box underneath the continental segment of subducting plate. Mantle plume impingement on lithospheric bottom leads to thinning of continental lithosphere and decompressional melting of both lithospheric and sublithospheric mantle along stretched trench-parallel zone. Further continental breakup is followed by opening of an oceanic basin separating a newly formed microcontinent from the main subducting continent. Despite continuous push applied at the boundary of subducting plate, plume-induced oceanic basin opens during several Myrs reaching several hundred kilometers wide. Cooling of the mantle plume and beginning of collision between the separated microcontinent and the overriding continental plate lead to gradual closure of newly formed oceanic basin that gets further involved into subduction and collision. The final stage sees continental subduction of main body of subducting plate and simultaneous tectonic exhumation of the upper crust of the subducted microcontinent. This scenario involving a plume-induced rifting of a microcontinent away from main body of subducted plate can be compared to the Mesozoic-Cenozoic development of the African plate characterized by the consecutive separation of the Apulian microcontinent and Arabian plate (in the Jurassic and the Neogene, respectively) during subduction of Neo-Tethys oceanic lithosphere beneath the Eurasian margin.

  17. Tidal breakup of triple stars in the Galactic Centre

    Science.gov (United States)

    Fragione, Giacomo; Gualandris, Alessia

    2018-01-01

    The last decade has seen the detection of fast moving stars in the Galactic halo, the so-called hypervelocity stars (HVSs). While the bulk of this population is likely the result of a close encounter between a stellar binary and the supermassive black hole (MBH) in the Galactic Centre (GC), other mechanims may contribute fast stars to the sample. Few observed HVSs show apparent ages which are shorter than the flight time from the GC, thereby making the binary disruption scenario unlikely. These stars may be the result of the breakup of a stellar triple in the GC which led to the ejection of a hypervelocity binary (HVB). If such binary evolves into a blue straggler star due to internal processes after ejection, a rejuvenation is possible that make the star appear younger once detected in the halo. A triple disruption may also be responsible for the presence of HVBs, of which one candidate has now been observed. We present a numerical study of triple disruptions by the MBH in the GC and find that the most likely outcomes are the production of single HVSs and single/binary stars bound to the MBH, while the production of HVBs has a probability ≲ 1% regardless of the initial parameters. Assuming a triple fraction of ≈10% results in an ejection rate of ≲ 1{ Gyr}^{-1}, insufficient to explain the sample of HVSs with lifetimes shorter than their flight time. We conclude that alternative mechanisms are responsible for the origin of such objects and HVBs in general.

  18. Beam breakup instability suppression in multicell superconducting rf guns

    Directory of Open Access Journals (Sweden)

    V. Volkov

    2011-05-01

    Full Text Available In this paper, we provide an analytical description for transverse coupling impedances with dipole high order modes (HOMs and beam breakup (BBU instability suppression of relativistic, high-current beams undergoing strong acceleration, such as those typically produced by rf photoinjectors. The model adopted is based on the accepted theory of coupling impedances extended to the case of beams characterized by a fast transition due to strong acceleration, from the nonrelativistic to the relativistic regime in which a bunch trajectory may not be rigidly directed parallel to the axis of the electric field. The trajectory oscillations in a dipole HOM field in the transverse plane are effective in perturbing the bunch energy, which causes an increase of the coupling impedance up to the BBU instability. This BBU instability analysis is based on equations obtained by Volkov [Phys. Rev. ST Accel. Beams 12, 011301 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.011301] in which external focusing due to both the applied transverse electric (TE HOM and the accelerating fundamental mode as well as dipole HOM damping by external loads are investigated. This analysis is valid in the limit in which the weak nonlinearity of applied fields near the axis may be neglected. The solution suggests a means of enhancing the BBU threshold current. The possibility of obtaining BBU instability suppression in a long, integrated photoinjector and linac structure, such as the superconducting rf source at Forschungs Zentrum Dresden (FZD, are numerically examined. New designs of photoinjectors that provide BBU instability suppression of all dipole HOMs to enhance the threshold currents are suggested.

  19. Energy spectra of protons in diffraction break-up of deuterons on 12C and 40Ca at intermediate energies

    Directory of Open Access Journals (Sweden)

    V. V. Davydovskyy

    2016-08-01

    Full Text Available In the diffraction approximation generalized to the case of inelastic processes with longitudinal momentum transfer, the reaction of the deuteron break-up on nuclei at medium energies is studied, taking into account the Coulomb and nuclear interactions. The formulas for the calculation of the energy spectra of the emerging protons are obtained up to the second order with respect to the ratio of the deuteron radius to the nucleus radius. Three types of model wave functions of the deuteron were used in the calculations: Yukawa, exponential and Gaussian. The wave function of np-pair in continuum is built orthogonal to the wave function of deuteron. This allows one to take into account qualitatively the interaction in the final state and avoid false contributions to the cross section at near zero momentum transfer. A comparison with experimental data on the break-up of deuterons with energy of 56 MeV on carbon and calcium with the registration of the emitted neutrons and protons at zero angles is carried out. It is shown that the contribution of the Coulomb mechanism dominates in the cross section. The best description of the spectra of protons is achieved by using the Yukawa form of the wave function of the deuteron. It is also shown that taking into account the transfer of longitudinal momentum to the deuteron nucleons improves the experimental data description. In the case of non-zero nucleon escape angles, the effect of taking into account longitudinal momentum can reach several hundred percent.

  20. Development of the VESUVIUS module. Molten jet breakup modeling and model verification

    Energy Technology Data Exchange (ETDEWEB)

    Vierow, K. [Nuclear Power Engineering Corp., Tokyo (Japan); Nagano, Katsuhiro; Araki, Kazuhiro

    1998-01-01

    With the in-vessel vapor explosion issue ({alpha}-mode failure) now considered to pose an acceptably small risk to the safety of a light water reactor, ex-vessel vapor explosions are being given considerable attention. Attempts are being made to analytically model breakup of continuous-phase jets, however uncertainty exists regarding the basic phenomena. In addition, the conditions upon reactor vessel failure, which determine the starting point of the ex-vessel vapor explosion process, are difficult to quantify. Herein, molten jet ejection from the reactor pressure vessel is characterized. Next, the expected mode of jet breakup is determined and the current state of analytical modeling is reviewed. A jet breakup model for ex-vessel scenarios, with the primary breakup mechanism being the Kelvin-Helmholtz instability, is described. The model has been incorporated into the VESUVIUS module and comparisons of VESUVIUS calculations against FARO L-06 experimental data show differences, particularly in the pressure curve and amount of jet breakup. The need for additional development to resolve these differences is discussed. (author)

  1. Western Canadian Arctic ringed seal organic contaminant trends in relation to sea ice break-up.

    Science.gov (United States)

    Gaden, A; Ferguson, Steve H; Harwood, L; Melling, H; Alikamik, J; Stern, G A

    2012-04-17

    The association between changing sea ice conditions and contaminant exposure to Arctic animals interests Inuvialuit harvesters, communities, and researchers. We examined organochlorine contaminant (OC) concentrations in the blubber of 90 male adult ringed seals (Phoca hispida) sampled from the subsistence harvest in Ulukhaktok (formerly Holman), NT, Canada, just prior to break-up of the sea ice (1993-2008). OC blubber concentrations were assessed with respect to year and sea ice break-up date. HCB and age- and blubber-adjusted concentrations of p,p'-DDT and ΣCHB (chlorobornane) significantly decreased over the study period. With respect to the timing of the spring break-up, highly lipophlic OCs, such as p,p'-DDE and PCB 153, were higher during years of early ice clearing (at least 12 days earlier than the mean annual break-up date), whereas no trends were observed for α, β, and γ isomers of HCH, trans- and cis-chlordane, oxychlordane, or ΣCHB. The higher contaminant concentrations found in earlier break-up years is likely due to earlier and/or increased foraging opportunities. This situation also has potential for enhancing bioaccumulation and biomagnification of contaminants over the long-term if projected changes continue to result in lighter and earlier ice conditions.

  2. Mechanism of Water Droplet Breakup Near the Leading Edge of an Airfoil

    Science.gov (United States)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida, Garcia

    2012-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 microns, and airfoil velocities of 70 and 90 m/sec.

  3. Effects of the geometric orientations of the nozzle exit on the breakup of free liquid jet

    Energy Technology Data Exchange (ETDEWEB)

    Lad, V. N.; Murthy, Z. V. P. [Sardar Vallabhbhai National Institute of Technology, Gujarat (India)

    2016-04-15

    Free liquid jets are produced through various geometric orientations of the nozzle exit. The breakup lengths of liquid jets under various geometric orientations of the nozzle exit were studied. Images of jets were captured using a high-speed camera with a maximum frame rate of 1000 frames per second and were analyzed to determine the dynamics between jets and breakup lengths. The breakup length of jets changes with the cut angle of the nozzle exit. In addition, adding polymer reduces the effect of the cut angle of the nozzle exit on the breakup length for an entire range of velocities. The effect of the cut angle on breakup length is predominant for aqueous solutions with surfactants. This work provides motivation for further computational research to study jet dynamics in a partially covered nozzle exit, such as the case in which the boundary conditions near the nozzle opening is more complex with the cut angle and its vertex position, which directly reflects liquid jet dynamics.

  4. Investigation on Shock Induced Stripping Breakup Process of A Liquid Droplet

    KAUST Repository

    Liu, Yao

    2017-03-02

    Stripping breakup process of a single liquid droplet under the impact of a planar shock wave is investigated both experimentally and numerically. The droplet breakup experiment is conducted in a horizontal shock tube and the evolution of the droplet is recorded by direct high-speed photography. The experimental images clearly illustrate the droplet interface evolution features from its early to relatively late stage. Compressible Euler equations are solved using an in-house inviscid upwind characteristic space-time conservation element and solution element (CE/SE) method coupled with the HLLC approximate Riemann solver. A reduced five-equation model is employed to demonstrate the air/liquid interface. Numerical results accurately reproduce the water column and axi-symmetric water droplet breakup processes in experiments. The present study confirms the validity of the present numerical method in solving the shock wave induced droplet breakup problem and elaborates the stripping breakup process numerically in a long period. Droplet inner flow pattern is depicted, based on which the drives of protrusions emerged on the droplet surface are clearly seen. The droplet deformation is proved to be determined by not only the outer air flow, but also the inner liquid flow.

  5. Physics-Based Modeling of Meteor Entry and Breakup

    Science.gov (United States)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kang; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; hide

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup.Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood.On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/sq cm. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  6. Droplet Deformation Prediction With the Droplet Deformation and Breakup Model (DDB)

    Science.gov (United States)

    Vargas, Mario

    2012-01-01

    The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

  7. Evidence for a T-shape break-up pattern in the triple photoionization of Li.

    Science.gov (United States)

    Colgan, J; Emmanouilidou, A; Pindzola, M S

    2013-02-08

    We examine the angular distributions of all three electrons ionized from Li by a single photon near the triple ionization threshold using a fully quantum-mechanical treatment. We find strong evidence for a T-shape break-up pattern at a 5 eV excess energy as previously predicted by quasiclassical simulations [A. Emmanouilidou and J. M. Rost, J. Phys. B 39, 4037 (2006); A. Emmanouilidou, P. Wang, and J. M. Rost, Phys. Rev. Lett. 100, 063002 (2008)]. This finding is in conflict with the expected Wannier break-up dynamics of three electrons moving at mutual angles of 120°, which is expected to hold at energies a few eV above threshold. We use our quantum-mechanical approach to explore the physical mechanisms behind this unusual break-up configuration.

  8. Oil slicks on water surface: Breakup, coalescence, and droplet formation under breaking waves.

    Science.gov (United States)

    Nissanka, Indrajith D; Yapa, Poojitha D

    2017-01-15

    The ability to calculate the oil droplet size distribution (DSD) and its dynamic behavior in the water column is important in oil spill modeling. Breaking waves disperse oil from a surface slick into the water column as droplets of varying sizes. Oil droplets undergo further breakup and coalescence in the water column due to the turbulence. Available models simulate oil DSD based on empirical/equilibrium equations. However, the oil DSD evolution due to subsequent droplet breakup and coalescence in the water column can be best represented by a dynamic population model. This paper develops a phenomenological model to calculate the oil DSD in wave breaking conditions and ocean turbulence and is based on droplet breakup and coalescence. Its results are compared with data from laboratory experiments that include different oil types, different weathering times, and different breaking wave heights. The model comparisons showed a good agreement with experimental data. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Fluid breakup in carbon nanotubes: An explanation of ultrafast ion transport

    Science.gov (United States)

    Gao, Xiang; Zhao, Tianshou; Li, Zhigang

    2017-09-01

    Ultrafast ion transport in carbon nanotubes (CNTs) has been experimentally observed, but the underlying mechanism is unknown. In this work, we investigate ion transport in CNTs through molecular dynamics (MD) simulations. It is found that the flow in CNTs undergoes a transition from the passage of a continuous liquid chain to the transport of isolated ion-water clusters as the CNT length or the external electric filed strength is increased. The breakup of the liquid chain in CNTs greatly reduces the resistance caused by the hydrogen bonds of water and significantly enhances the ionic mobility, which explains the two-order-magnitude enhancement of ionic conductance in CNTs reported in the literature. A theoretical criterion for fluid breakup is proposed, which agrees well with MD results. The fluid breakup phenomenon provides new insights into enhancing ion transport in nanoconfinements.

  10. Capture cross-section and rate of the 14 C (n, γ) 15 C reaction from ...

    Indian Academy of Sciences (India)

    We calculate the Coulomb dissociation of 15C on a Pb target at 68 MeV/u incident beam energy within the fully quantum mechanical distorted wave Born approximation formalism of breakup reactions. The capture cross-section and the subsequent rate of the 14C(, )15C reaction are calculated from the ...

  11. Preventing alternans-induced spiral wave breakup in cardiac tissue: An ion-channel-based approach

    Science.gov (United States)

    Allexandre, D.; Otani, N. F.

    2004-12-01

    The detailed processes involved in spiral wave breakup, believed to be one major mechanism by which tachycardia evolves into fibrillation, are still poorly understood. This has rendered difficult the proper design of an efficient and practical control stimulus protocol to eliminate such events. In order to gain new insights into the underlying electrophysiological and dynamical mechanisms of breakup, we applied linear perturbation theory to a steadily rotating spiral wave in two spatial dimensions. The tissue was composed of cells modeled using the Fenton-Karma equations whose parameters were chosen to emphasize alternans as a primary mechanism for breakup. Along with one meandering mode, not just one but several unstable alternans modes were found with differing growth rates, frequencies, and spatial structures. As the conductance of the fast inward current was increased, the instability of the modes increased, consistent with increased meandering and propensity for spiral breakup in simulations. We also explored a promising new approach, based on the theory, for the design of an energy efficient electrical stimulus protocol to control spiral wave breakup. The novelty lies in addressing the problem directly at the ion channel level and taking advantage of the inherent two dimensional nature of the rotating wave. With the help of the eigenmode method, we were able to calculate the exact timing and amplitude of the stimulus, and locate it optimally to maximize efficiency. The analysis led to a special-case example that demonstrated that a single, properly timed stimulus can have a global effect, suppressing all growing alternans modes over the entire tissue, thus inhibiting spiral wave breakup.

  12. Contributions of evaporation and other mechanisms to tear film thinning and break-up.

    Science.gov (United States)

    King-Smith, P Ewen; Nichols, Jason J; Nichols, Kelly K; Fink, Barbara A; Braun, Richard J

    2008-08-01

    To evaluate the contribution of three mechanisms-evaporation of the tear film, inward flow of water into the corneal epithelium or contact lens, and "tangential flow" along the surface of epithelium or contact lens-to the thinning of the tear film between blinks and to tear film break-up. In addition to a discussion of relevant studies, some previously unpublished images are presented illustrating aspects of tear film break-up. CONTRIBUTIONS OF THREE MECHANISMS TO TEAR FILM BREAK-UP: Inward flow of water into the epithelium or contact lens is probably unimportant, and a small flow in the opposite direction may actually occur. Tangential flow is probably important in certain special cases of tear film break-up-at the black line near the tear meniscus, over surface elevations, after partial blinks, and from small thick lipid spots in the tear film. In all these special cases it is argued that tangential flow is important initially, but evaporation may be needed for final thinning to break-up. It is argued that most of the observed tear film thinning between blinks is due to evaporation, rather than tangential flow, and that large "pool" break-up regions are the result of evaporation over an extended area. Evaporation in our "free-air" conditions may be four to five times faster than the average of the values reported in the literature when air currents are prevented by preocular chambers. However, recent evaporation measurements using "ventilated chambers" give higher values, which may correspond better to free-air conditions. Thus evaporation may be fast enough to explain many cases of tear film break-up, and to give rise to considerable increases in the local osmolarity of the tear film between blinks.

  13. Post-breakup burial and exhumation of passive continental margins: nine propositions to inform geodynamic models

    Science.gov (United States)

    Green, Paul F.; Duddy, Ian; Japsen, Peter; Chalmers, James; Bonow, Johan

    2017-04-01

    Despite many years of study, the processes involved in the post-breakup development of passive margins remain poorly understood. Integration of apatite fission track analysis (AFTA) and stratigraphic landscape analysis (SLA) at a number of margins has provided new insights into the development of elevated passive continental margins (EPCMs). In particular, these studies have highlighted the importance of integrating evidence from the preserved rock record with information on the deposition and erosional removal of rock units which are no longer present ("missing section"). From these studies we have formulated nine propositions regarding the formation of EPCMs and the nature of the controlling processes, viz: 1: EPCMs are not the inevitable consequence of rifting and breakup 2: Elevated topography at present-day EPCMs developed long after breakup 3: Similar EPCM landscapes at different margins suggest similar controlling processes 4: EPCMs undergo episodic burial and exhumation rather than slow monotonic denudation, both before rifting and after breakup 5: Post-breakup exhumation at continental margins is not restricted to elevated onshore regions 6: Post-breakup burial and exhumation have affected low lying margins as well as EPCMs 7: Episodic km-scale exhumation and re-burial also affects cratonic regions 8: Exhumation events show a broad level of synchroneity across continents and oceans and correlate with plate boundary events and changes in plate motions. 9: EPCMs are located where there is an abrupt, lateral change in crustal or lithospheric thickness These propositions imply that positive and negative vertical motions at passive margins are controlled by plate-scale processes. Many of these key aspects are absent from current geodynamic models of passive margin development. Understanding the processes that control vertical movements at passive continental margins requires development of realistic geodynamic models that honour these propositions.

  14. The effects of nozzle geometry on waterjet breakup at high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Vahedi Tafreshi, H.; Pourdeyhimi, B. [Nonwovens Cooperative Research Center, North Carolina State University, NC 27695-8301, Raleigh (United States)

    2003-10-01

    Waterjet breakup is traditionally considered to follow the Ohnesorge classification. In this classification, high Reynolds number waterjets are considered to atomize quickly after discharge. By generating a constricted waterjet where the water flow stays detached all the way through the nozzle, we have observed the first wind-induced breakup mode at high Reynolds numbers. Such a peculiar behavior, however, was not observed in non-constricted waterjets. Our results indicate that, constricted jets do not follow the Ohnesorge classification, in contrast to the non-constricted waterjets. We discuss the impact of nozzle geometry on the characteristics of waterjets and support our discussion by numerical simulations. (orig.)

  15. Beam Break-up Instability in the CERN PS near Transition

    CERN Document Server

    Cappi, R; Métral, G

    2000-01-01

    Fast beam losses, due to a vertical coherent instability of high frequency, have been observed in the PS near transition energy, with the high-intensity single-bunch beam for the neutron Time-of-Flight facility (n-ToF). By increasing the longitudinal emittance, the beam could be stabilised. These phenomena can be described by the beam breakup theory, since near transition the longitudinal positions of particles are almost frozen, as in the linac case. Comparison between observations and theory, using Brandt and Gareyte's formula for single-bunch beam breakup in circular accelerators, shows good agreement.

  16. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    Directory of Open Access Journals (Sweden)

    Chakraborty S.

    2014-03-01

    Full Text Available Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

  17. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    Science.gov (United States)

    Chakraborty, S.; Datta Pramanik, U.; Aumann, T.; Beceiro, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chatterjee, S.; Chartier, M.; Cortina-Gil, D.; De Angelis, G.; Gonzalez-Diaz, D.; Emling, H.; Diaz Fernandez, P.; Fraile, L. M.; Ershova, O.; Geissel, H.; Heil, M.; Jonson, B.; Kelic, A.; Johansson, H.; Kruecken, R.; Kroll, T.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Munzenberg, G.; Marganiec, J.; Nociforo, C.; Najafi, A.; Panin, V.; Paschalis, S.; Pietri, S.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Ray, J.; Simon, H.; Scheidenberger, C.; Typel, S.; Taylor, J.; Togano, Y.; Volkov, V.; Weick, H.; Wagner, A.; Wamers, F.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2014-03-01

    Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s)⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

  18. Cumulative Beam Breakup in Linear Accelerators with Arbitrary Beam Current Profile

    Energy Technology Data Exchange (ETDEWEB)

    Jean Delayen

    2003-06-01

    An analytical formalism for the solution of cumulative beam breakup in linear accelerators with arbitrary time dependence of beam current is presented, and a closed-form expression for the time and position dependence of the transverse displacement is obtained. It is applied to the behavior of single bunches and to the steady state and transient behavior of dc beams and beams composed of point-like and finite length bunches. This formalism is also applied to the problem of cumulative beam breakup in the presence of random displacement of cavities and focusing elements, and a general solution is presented.

  19. Dye Tracers for Characterizing Breakup in Arctic Rivers: An Old School Solution for a Modern Conundrum

    Science.gov (United States)

    Schnabel, W.; Stephan, N.; Toniolo, H. A.; Kane, D. L.

    2011-12-01

    Discharge in arctic rivers is often near its annual maximum during spring breakup. However, the presence swiftly moving ice at this time of year leads to unsafe boating conditions, thus complicating the collection of discharge information through modern methods such as acoustic Doppler current profiling (ADCP). In this paper, we report the results of a study designed to evaluate the breakup discharge of Alaska's Itkillik River using Rhodamine WT, a fluorescent dye. Notable advantages of the method included the ability to inject and collect the dye without entering the water. A disadvantage of the method was the confounding effects of turbidity and/or suspended solids.

  20. Computational modeling of ice cracking and break-up from helicopter blades

    KAUST Repository

    Shiping, Zhang

    2012-06-25

    In order to reduce the danger of impact onto components caused by break-up, it is important to analyze the shape of shed ice accumulated during flight. In this paper, we will present a 3D finite element method (FEM) to predict the shed ice shape by using a fluid-solid interaction (FSI) approach to determine the loads, and linear fracture mechanics to track crack propagation. Typical icing scenarios for helicopters are analyzed, and the possibility of ice break-up is investigated.

  1. Breakup magmatism on the North Atlantic Igneous Province: what could we learn about the extension/breakup processes from the Norwegian Margin?

    Science.gov (United States)

    Mansour Abdelmalak, Mohamed; Planke, Sverre; Faleide, Jan Inge; Myklebust, Reidun; Gernigon, Laurent; Horni, Jim; Wong, Po-Wan

    2013-04-01

    The early continental breakup and initial seafloor spreading in the northeast Atlantic area was accompanied by widespread intrusive and extrusive volcanism. New and reprocessed seismic reflection allow for detailed seismic volcanostratigraphy interpretation of the breakup complex and sub-basalt sequences. Several distinct volcanic seismic facies units have been identified: (1) Landward Flows, (2) Lava Delta, (3) Inner Flows, (4) Inner Seaward Dipping Reflectors (Inner SDR), (5) Outer High, (6) Outer SDR. Such facies succession represents a typical volcanic rifted margin and defines the extent of the breakup extrusive complex landward of the first magnetic seafloor spreading anomaly. We present an updated map of the volcanic seismic facies units in the northeast Atlantic area based on high-quality geophysical data combined with the newest published and unpublished data. The Norwegian margin shows an along-strike segmentation that seems to be in relation with the margin inheritance. We notice that this segmentation affect also melt production in the area and LCB (lower Crustal Bodies) extent. The lateral variation of LCB thickness could be interpreted as a variation of melt supply during the extension/breakup process which is also controlled by the crustal inheritance. The updated imaging of the sub-basalt facies and the deep crustal mapping provides important constrain on the pre-volcanic basin configuration, margin subsidence history, and the volume of igneous rocks. These constraints lead to a better understanding of the melt supply from the upper mantle and the relationship between tectonic setting and volcanism. The result gives key boundary conditions for understanding the processes forming volcanic margins and constraints on the thermal evolution of associated prospective volcanic basins.

  2. Low probability, high impact: the implications of a break-up of China for carbon dioxide emissions

    NARCIS (Netherlands)

    Tol, R.S.J.

    2013-01-01

    The transition from autocracy to democracy may lead a country to break-up. The break-ups of the USSR and Yugoslavia led to sharp falls in the level of emissions (while pre- and post-crisis trends are similar). If something like that would happen in China, an event with an unknown but small

  3. Experimental study of drop breakup in a turbulent flow; Etude experimentale de la rupture de gouttes dans un ecoulement turbulent

    Energy Technology Data Exchange (ETDEWEB)

    Galinat, S.

    2005-04-15

    This work presents the drop breakup phenomenon in a turbulent flow induced by a cross-section restriction in a pipe. A global analysis of single-drop breakup, in a finite volume downstream of the orifice, has allowed deriving statistical quantities such as the break-up probability and the daughter-drop distribution. These parameters are function of a global Weber number based on the maximal pressure drop through the orifice. At a local scale, the locations of breakup events are distributed heterogeneously and depend on the flow Reynolds number. The local hydrodynamic study in downstream of the orifice, which has been done by using Particle Image Velocimetry, reveals the specific breakup zones. Otherwise, this analysis has proved that the turbulence is the predominant external stress at the drop scale. The relation between drop deformation and the external stress along the trajectory has been simulated numerically by the response of a damped oscillator to the locally measured instantaneous turbulence forcing. The results of statistical analysis have allowed to introduce a breakup criterion, based on a unique deformation threshold value for all experiments. This multi-scale approach has been conducted to study drop breakup mechanisms in a concentrated dispersion. The breakup probability decrease with the increase of dispersed phase concentration, which influences the turbulent Weber number distribution in downstream of the orifice. (author)

  4. Continuous monitoring of the effects of coagulants during aggregation and breakup process; Monitoraggio in continuo degli effetti di alcuni coagulanti nel processo di aggregazione e rottura

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, J. [London Univ., London (United Kingdom). Dept. of Civil and Environmental Engineering; Lubello, C.; Rossi, L. [Florence Univ., Florence (Italy). Dipt. di Ingegneria Civile

    2000-04-01

    In the present work we have applied a methodology based on the theory of fluctuation of turbidity (Gregory and Nelson, 1984) for the continuous monitoring of a flocculation process. Such method has been used to define a few significative parameters in the aggregation and break-up phases. For this scope, we used simple technique, based on measurements of fluctuation in light transmission through a suspension, which can give very useful information on the state of aggregation of particles defining a flocculation index (FI). The first experimental results applied to a kaolin suspension with three different coagulant (PAX-XL1, PAX-XL19, ALUM) are encouraging. In particular it was possible to calculate some interesting parameters like reaction time, growing velocity, dimension, break-up resistant and the strength. A particularly interesting result concern the proposed procedure to calculate the break-up resistance and the strength parameters. [Italian] In questo lavoro e' stata applicata la teoria della fluttuazione della torbidita' per il controllo in continuo del processo di coagulazione-flocculazione proposta da Gregory e Nelson (1984) allo scopo di definire alcuni parametri significativi per l'analisi del processo di aggregazione e rottura di una sospensione. A tale scopo e' stata utilizzata una semplice, tecnica basata sulla misurazione della fluttuazione della luce trasmessa attraverso un flusso di sospensione, in grado di fornire informazioni molto utili sullo stato di aggregazione delle particelle attraverso la misura dell'indice di flocculazione. I primi risultati sperimentali applicati ad una sospensione di caolino con tre diversi tipi di coagulanti commerciali (PAX-XL1, PAX-XL19, Solfato di Alluminio) forniscono indicazioni molto incoraggianti. In particolare e' stato possibile definire e calcolare, in condizioni di miscelazione rapida, alcuni parametri quali tempo di reazione, velocita' di accrescimento, dimensione

  5. Large-eddy simulation of cavitating nozzle flow and primary jet break-up

    NARCIS (Netherlands)

    Örley, F.; Trummler, T.; Hickel, S.; Mihatsch, M.S.; Schmidt, S.J.; Adams, N.A.

    2015-01-01

    We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating

  6. Visualization of droplet break-up in pre-mix membrane emulsification using microfluidic devices

    NARCIS (Netherlands)

    Zwan, van der E.A.; Schroën, C.G.P.H.; Dijke, van K.C.; Boom, R.M.

    2006-01-01

    To investigate the break-up of emulsion droplets in pre-mix or dead-end membrane emulsification, a microscopic study was conducted in microfluidic devices. Channels with shapes such as constrictions, junctions, and combinations thereof representing ideal membrane structures where etched in silicon.

  7. Restructuring and break-up of two-dimensional aggregates in shear flow.

    Science.gov (United States)

    Vassileva, Nikolina D; van den Ende, Dirk; Mugele, Frieder; Mellema, Jorrit

    2006-05-23

    We consider single two-dimensional aggregates, containing glass particles, placed at a water/air interface. We have investigated the critical shear rate for break-up of aggregates with different sizes in a simple shear flow. All aggregates break-up nearly at the same shear rate (1.8 +/- 0.2 s(-)(1)) independent of their size. The evolution of the aggregate structure before break-up was also investigated. With increasing shear rate, the aggregates adopt a more circular shape, and the particles order in a more dense, hexagonal structure. A simple theoretical model was developed to explain the experimentally observed break-up. In the model, the aggregate is considered as a solid circular disk that will break near its diameter. The capillary and drag force on the two parts of the aggregate were calculated, and from this force balance, the critical shear rate was found. The model shows a weak size dependence of the critical shear rate for the considered aggregates. This is consistent with the experimental observations.

  8. Tear break-up time in eyes with pterygia and pingueculae in Ibadan ...

    African Journals Online (AJOL)

    Study design: The tear film has been studied using tear break-up time (TBUT) in adults with pterygia and pingueculae disorders, TBUT was measured in 73 eyes with pterygia and 74 eyes with pinguecula and were compared to TBUT in 74 eyes of age and sex matched normal controls. Abnormal TBUT was defined as TBUT ...

  9. The relation between invasive and non-invasive tear break-up time ...

    African Journals Online (AJOL)

    Tear stability normal to Nigerians with consideration of gender and age has not been reported. Tear stability in young adults was measured using invasive and non-invasive tear break-up time (TBUT and NIBUT). Forty –five subjects aged 20 to 30 years were selected from among the students of University of. Benin, Edo ...

  10. Break-up of a non-Newtonian jet injected downwards in a ...

    Indian Academy of Sciences (India)

    phenomenological constitutive equation that accounts for both rate-thinning and rate- thickening. ... At smaller, intermediate and larger values of Vav,i, the regimes found are periodic uniform drop. (P-UD) ...... Christanti Y and Walker L M 2001 Surface tension driven jet breakup of strain-hardening polymer solutions.

  11. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    NARCIS (Netherlands)

    Chakraborty, S.; Pramanik, U. Datta; Aumann, T.; Beceiro, S.; Boretzky, K.; Caesar, C.; Carlson, B.V.; Catford, W.N.; Chatterjee, S.; Chartier, M.; Cortina-Gil, D.; Angelis, G.De; Gonzalez - Dias, D.; Emling, H.; Diaz Fernandes, P.; Fraile, L.M.; Ershova, O.; Geissel, H.; Heil, M.; Jonson, B.; Kelic, A.; Johansson, H.; Kruecken, R.; Kroll, T.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Munzenberg, G.; Marganiec, J.; Nociforo, C.; Najafi, A.; Panin, V.; Paschalis, S.; Pietri, S.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Ray, J.; Simon, H.; Scheidenberger, C.; Typel, S.; Taylor, J.; Togano, Y.; Volkov, V.; Weick, H.; Wagner, A.; Wamers, F.; Weigand, M.; Winfield, J.S.; Yakorev, D.; Zoric, M.

    2014-01-01

    Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup

  12. Break-up of droplets in a concentrated emulsion flowing through a narrow constriction

    Science.gov (United States)

    Kim, Minkyu; Rosenfeld, Liat; Tang, Sindy; Tang Lab Team

    2014-11-01

    Droplet microfluidics has enabled a wide range of high throughput screening applications. Compared with other technologies such as robotic screening technology, droplet microfluidics has 1000 times higher throughput, which makes the technology one of the most promising platforms for the ultrahigh throughput screening applications. Few studies have considered the throughput of the droplet interrogation process, however. In this research, we show that the probability of break-up increases with increasing flow rate, entrance angle to the constriction, and size of the drops. Since single drops do not break at the highest flow rate used in the system, break-ups occur primarily from the interactions between highly packed droplets close to each other. Moreover, the probabilistic nature of the break-up process arises from the stochastic variations in the packing configuration. Our results can be used to calculate the maximum throughput of the serial interrogation process. For 40 pL-drops, the highest throughput with less than 1% droplet break-up was measured to be approximately 7,000 drops per second. In addition, the results are useful for understanding the behavior of concentrated emulsions in applications such as mobility control in enhanced oil recovery.

  13. Breakup of 42 MeV Li projectiles in the fields of C and Au nuclei ...

    Indian Academy of Sciences (India)

    (2). The TSM cross section is the expression without the factor in the large parentheses of eq. (1). Similar approaches were also followed in [6,7] and breakup cross sections were observed to be as large as fusion cross sections. To account for the deflection ( c) of the observed particle in the target Coulomb and nuclear field,.

  14. Bouncing Back from a Breakup: Attachment, Time Perspective, Mental Health, and Romantic Loss

    Science.gov (United States)

    Gilbert, Steven P.; Sifers, Sarah K.

    2011-01-01

    Coping with a romantic breakup is a normal developmental task of emerging adulthood. Because of their role in influencing interpersonal relationships and adjustment, attachment history and time perspectives may influence resilience to romantic loss. In an online survey of 1,404 university students ages 18-25 who reported experiencing recent…

  15. Neutron Beams from Deuteron Breakup at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, M.A.; Ahle, L.; Bleuel, D.L.; Bernstein, L.; Braquest, B.R.; Cerny, J.; Heilbronn, L.H.; Jewett, C.C.; Thompson, I.; Wilson, B.

    2007-07-31

    Accelerator-based neutron sources offer many advantages, in particular tunability of the neutron beam in energy and width to match the needs of the application. Using a recently constructed neutron beam line at the 88-Inch Cyclotron at LBNL, tunable high-intensity sources of quasi-monoenergetic and broad spectrum neutrons from deuteron breakup are under development for a variety of applications.

  16. Wilson cycle passive margins: Control of orogenic inheritance on continental breakup

    DEFF Research Database (Denmark)

    Petersen, Kenni D.; Schiffer, Christian

    2016-01-01

    Abstract Rifts and passive margins often develop along old suture zones where colliding continents merged during earlier phases of the Wilson cycle. For example, the North Atlantic formed after continental break-up along sutures formed during the Caledonian and Variscan orogenies. Even though suc...... as igneous bodies. The latter is consistent with dipping sub-Moho reflectors often observed in passive margins....

  17. A Qualitative Study on the Emotional Healing Efficacy of Movies for Undergraduates Suffering Breakups

    Directory of Open Access Journals (Sweden)

    Chen Su-may Sheih

    2016-12-01

    Full Text Available Breakups with significant others are among the main reasons for emotional disturbance problems in Taiwanese undergraduates. Most undergraduates lack emotional regulation; therefore, their negative emotions can easily accumulate, influencing their mental health. Exacerbating these effects, the accumulation of negative emotions can lead to social problems. Therefore, helping undergraduates appropriately cope with negative emotions generated by breakups is a topic worth exploring. Movie therapy involves watching appropriate movies for soothing negative emotions. To investigate the emotional healing efficacy of movies, this study employed content analysis to select movies about breakups and recruited 14 undergraduates suffering from breakups. Semi-structured in-depth interviews were conducted after the subjects viewed one of the movies, and the emotional healing efficacy of movies was analyzed based on whether the subjects experienced the processes of identification, catharsis, and insight. The findings indicated that 14 movies had emotional healing efficacy. The subjects experienced emotional healing from movies that contained three critical elements: similarity of backgrounds between the viewer and the movie characters, the extroversive expression of the movie characters’ emotions, and the characters’ demonstration of concrete solutions to the problems. [Article content in Chinese

  18. The effects of Vitamin A on tear break-up time of young adults ...

    African Journals Online (AJOL)

    This study was carried out to determine the effect of increased intake of vitamin A on Tear break-up time (TBUT). One hundred asymptomatic healthy young adults; 50 males and 50 females all within the ages of 18 and 30 years were used for this study. Results showed a range of 13-28 seconds and a mean TBUT of

  19. Novel Techniques for Quantification of Correlation Between Primary Liquid Jet Breakup and Downstream Spray Characteristics

    Science.gov (United States)

    2016-10-05

    unlimited. 5 1. Introduction Several liquid -fuelled combustion systems, such as liquid propellant rocket engines and gas turbines... liquid sheet[1], [2], [3]. Considering the challenges in studying spray combustion due to interacting complex physical and chemical processes...AFRL-AFOSR-JP-TR-2016-0084 Novel techniques for quantification of correlation between primary liquid jet breakup and downstream spray characteristics

  20. Type of Writing Task and College Students' Meaning Making Following a Romantic Breakup

    Science.gov (United States)

    Primeau, Joanna E.; Servaty-Seib, Heather L.; Enersen, Donna

    2013-01-01

    In this study, the authors examined the potential effects of type of writing task (loss/gain vs. general prompt) on the narrative content offered by college students (N = 41) who experienced romantic breakup. Qualitative analyses indicated differences based on type of writing task. Students who received the loss/gain prompt exhibited more…

  1. Sharing Remote and Local Information for Tracking Spring Breakup in the Mackenzie Delta and Beaufort Sea

    Science.gov (United States)

    Forbes, D. L.; Whalen, D.; Fraser, P.

    2015-12-01

    The Mackenzie Delta is the second largest on the Arctic Ocean, covering 13 000 km2. The annual flood regime in the delta is dominated by the spring snowmelt freshet and associated ice breakup, as water from the south arrives in the ice-covered delta and spreads over bottomfast and adjacent floating sea ice at the delta front. The complex processes of water-ice interaction, flow partitioning, and overbank flooding to replenish waters in 43 000 delta lakes threaten community, transportation, subsistence, and energy infrastructure in the delta. The annual breakup season is a time of rejuvenation, excitement, and anxiety for delta residents and stakeholders. To track the progress of breakup and meet the need for knowledge dissemination to the local communities, a Mackenzie-Beaufort breakup newsletter has been produced by Natural Resources Canada on a quasi-daily basis during the May-June spring flood season for 10 years, and distributed to an e-mail list that grew to over 300 subscribers. This provides near real-time tracking of water levels and breakup using on-line gauges (Environment Canada), daily MODIS satellite imagery (NASA), Landsat imagery (USGS) and intermittent radar imagery (various sources). In earlier years, information was also supplied from field programs operating in the delta during breakup, but changing priorities and funding have reduced the number of outside researchers present during these critical weeks. Meanwhile the number of local contributors has grown, providing observations and photographs to share with the local, regional and global readership. In this way the newsletter evolved into a two-way communication tool and community portal. The newsletter is a chronicle of each breakup season and a key resource for territorial and municipal managers, subsistence organizations, and emergency response agencies, with routine requests for specific imagery in areas of concern. With the completion of 10 years under the present model, we are exploring

  2. Using Synthetic Aperture Radar to Study River Ice Breakup on the Kuparuk River, Northern Alaska

    Science.gov (United States)

    Floyd, A.; Prakash, A.; Meyer, F. J.; Gens, R.; Liljedahl, A. K.

    2012-12-01

    A combined use of remote sensing techniques and in-situ measurements is an effective approach to study Arctic hydrology, given the vastness, complexity, and logistical challenges posed by most Arctic watersheds. Remote sensing techniques can provide tools to assess the geospatial variations that form the integrated response of a river system and, therefore, provide important details to study one of the effects of climate change on the remote Arctic environment. This study investigates the breakup response of the Kuparuk River on the North Slope of Alaska using synthetic aperture radar (SAR). Imagery and runoff data collected during the spring and summer months between 2001 and 2010 from the Lower Kuparuk River are included in the analysis, which totals 65 SAR images. Image processing results have been calibrated with in-situ stream gauge data provided by USGS gauging station 15896000, on the Lower Kuparuk River, near the town of Deadhorse, Alaska. A time series was assembled to examine the breakup initiation in the subsets through statistical analysis. Images were stacked, geocoded using a Fast Fourier Transform, subset, masked, and divided into subsections. The statistics of each subsection were then compiled and analyzed. Arctic river breakup is a dynamic process. Therefore, we expected drastic change in river surface conditions to correspond to a large variance in backscatter between river subsections. However, before and after breakup we expected image subsections to have largely homogenous statistics. This was verified in nearly all of the image sets, although some variance still existed before and after the breakup event as a result of other conflicting variables. Changes in wind velocity, water depth, and size of point bars all contributed to these confounding variances. Combined with a comprehensive field campaign, SAR imagery interpretations have the potential to develop into a useful monitoring tool for monitoring Arctic rivers and developing resource

  3. Post-breakup Basin Evolution along the South-Atlantic Margins

    Science.gov (United States)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2014-05-01

    The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment

  4. Breakup of 8B on 58Ni at energies around the Coulomb barrier and the astrophysical S17(0 factor revisited

    Directory of Open Access Journals (Sweden)

    Morales-Rivera J.C.

    2017-01-01

    Full Text Available Calculations of breakup and direct proton transfer for the 8B+58Ni system at energies around the Coulomb barrier (EB,lab=22.95 MeV were performed by the continuum-discretized coupled channels (CDCC method and the coupled-reaction-channels (CRC method, respectively. For the 7Be+58Ni interaction, we used a semimicroscopic optical model potential (OMP that combines microscopic calculations of the mean-field double folding potential and a phenomenological construction of the dynamical polarization potential (DPP. The 7Be angular distribution at Elab=25.75 MeV from the 8B breakup on 58Ni was calculated and the spectroscopic factor for 8B → 7Be+p vertex, Sexpt = 1.10 ± 0.05, was deduced. The astrophysical S17(0 factor was calculated equal to 20.7 ±1.1 eV•b, being in good agreement with the previously reported values.

  5. Attachment styles and personal growth following romantic breakups: the mediating roles of distress, rumination, and tendency to rebound.

    Directory of Open Access Journals (Sweden)

    Tara C Marshall

    Full Text Available The purpose of this research was to examine the associations of attachment anxiety and avoidance with personal growth following relationship dissolution, and to test breakup distress, rumination, and tendency to rebound with new partners as mediators of these associations. Study 1 (N = 411 and Study 2 (N = 465 measured attachment style, breakup distress, and personal growth; Study 2 additionally measured ruminative reflection, brooding, and proclivity to rebound with new partners. Structural equation modelling revealed in both studies that anxiety was indirectly associated with greater personal growth through heightened breakup distress, whereas avoidance was indirectly associated with lower personal growth through inhibited breakup distress. Study 2 further showed that the positive association of breakup distress with personal growth was accounted for by enhanced reflection and brooding, and that anxious individuals' greater personal growth was also explained by their proclivity to rebound. These findings suggest that anxious individuals' hyperactivated breakup distress may act as a catalyst for personal growth by promoting the cognitive processing of breakup-related thoughts and emotions, whereas avoidant individuals' deactivated distress may inhibit personal growth by suppressing this cognitive work.

  6. Two-valued breakup length of a water jet issuing from a finite-length nozzle under normal gravity.

    Science.gov (United States)

    Umemura, Akira; Kawanabe, Sho; Suzuki, Sousuke; Osaka, Jun

    2011-09-01

    Laboratory experiments are conducted in which water is issued vertically downward from a finite-length nozzle at a constant speed using a piston. The results of these experiments indicate that the breakup length of the liquid jet is two-valued at Weber numbers greater than unity but less than a certain value, which depends on the nozzle length-to-radius ratio and the Bond number. In addition to a long breakup length, which is consistent with the conventional observation, another shorter breakup length is realized at the same jet issue speed. Each experimental run for a specific jet issue speed begins from the start of liquid issue so that each run is independent of the other runs. Transition between the two breakup lengths seldom occurs in each run. Which of the two breakup lengths occurs is determined at the start of liquid issue, when the capillary wave produced by the liquid jet tip contraction easily reaches the nozzle exit. Unlike the conventional belief, which is based on the Plateau-Rayleigh instability theory, this experimental evidence demonstrates that liquid jet disintegration occurs in a deterministic manner. The previously proposed self-destabilizing mechanism of a liquid jet in microgravity, in which the origin of the unstable wave responsible for the breakups is attributed to the formation of an upstream propagating capillary wave at every breakup, is extended to explore the physics underlying the observed liquid jet disintegration behaviors.

  7. Attachment Styles and Personal Growth following Romantic Breakups: The Mediating Roles of Distress, Rumination, and Tendency to Rebound

    Science.gov (United States)

    Marshall, Tara C.; Bejanyan, Kathrine; Ferenczi, Nelli

    2013-01-01

    The purpose of this research was to examine the associations of attachment anxiety and avoidance with personal growth following relationship dissolution, and to test breakup distress, rumination, and tendency to rebound with new partners as mediators of these associations. Study 1 (N = 411) and Study 2 (N = 465) measured attachment style, breakup distress, and personal growth; Study 2 additionally measured ruminative reflection, brooding, and proclivity to rebound with new partners. Structural equation modelling revealed in both studies that anxiety was indirectly associated with greater personal growth through heightened breakup distress, whereas avoidance was indirectly associated with lower personal growth through inhibited breakup distress. Study 2 further showed that the positive association of breakup distress with personal growth was accounted for by enhanced reflection and brooding, and that anxious individuals’ greater personal growth was also explained by their proclivity to rebound. These findings suggest that anxious individuals’ hyperactivated breakup distress may act as a catalyst for personal growth by promoting the cognitive processing of breakup-related thoughts and emotions, whereas avoidant individuals’ deactivated distress may inhibit personal growth by suppressing this cognitive work. PMID:24066169

  8. Break-up characteristics of gelled propellant simulants with various gelling agent contents

    Science.gov (United States)

    Lee, Inchul; Koo, Jaye

    2010-12-01

    Gel propulsion systems have many advantages with respect to high performance, the energy management of liquid propulsion systems, storability, high density impulse, and low leakage of liquid propellants. The atomization process provides sufficient contact surface area between the gelled fuel and oxidizer jets. It is important to study how injection characteristics of gelled propellants are related with break-up and spray distribution. The break-up and mixing processes are very important in achieving maximum efficiency and necessitate the careful study of combustion instability. Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the break-up process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. Especially, the break-up processes of the impinging jets at the initial conditions are studied. The break-up process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids which are mixed by ionized water 98.5 wt%, Carbopol 941 0.5wt% or 1.0wt%, and NaOH(concentration 10%) 1.0wt%. For the like-on-like doublet injector, the generation of a liquid sheet at the impinging point of two jets was observed. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Generally, the break-up length decreased due to the increasing Reynolds number. However, surface waves and atomized droplets increased. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. Also, the rim patterns of spray have no disturbances on the spray sheet. As the

  9. Numerical and experimental study of liquid breakup process in solid rocket motor nozzle

    Science.gov (United States)

    Yen, Yi-Hsin

    Rocket propulsion is an important travel method for space exploration and national defense, rockets needs to be able to withstand wide range of operation environment and also stable and precise enough to carry sophisticated payload into orbit, those engineering requirement makes rocket becomes one of the state of the art industry. The rocket family have been classified into two major group of liquid and solid rocket based on the fuel phase of liquid or solid state. The solid rocket has the advantages of simple working mechanism, less maintenance and preparing procedure and higher storage safety, those characters of solid rocket make it becomes popular in aerospace industry. Aluminum based propellant is widely used in solid rocket motor (SRM) industry due to its avalibility, combusion performance and economical fuel option, however after aluminum react with oxidant of amonimum perchrate (AP), it will generate liquid phase alumina (Al2O3) as product in high temperature (2,700˜3,000 K) combustion chamber enviornment. The liquid phase alumina particles aggromorate inside combustion chamber into larger particle which becomes major erosion calprit on inner nozzle wall while alumina aggromorates impinge on the nozzle wall surface. The erosion mechanism result nozzle throat material removal, increase the performance optimized throat diameter and reduce nozzle exit to throat area ratio which leads to the reduction of exhaust gas velocity, Mach number and lower the propulsion thrust force. The approach to avoid particle erosion phenomenon taking place in SRM's nozzle is to reduce the alumina particle size inside combustion chamber which could be done by further breakup of the alumina droplet size in SRM's combustion chamber. The study of liquid breakup mechanism is an important means to smaller combustion chamber alumina droplet size and mitigate the erosion tack place on rocket nozzle region. In this study, a straight two phase air-water flow channel experiment is set up

  10. Brownian dynamics simulation of insulin microsphere formation from break-up of a fractal network.

    Science.gov (United States)

    Li, Wei; Gunton, J D; Khan, Siddique J; Schoelz, J K; Chakrabarti, A

    2011-01-14

    Motivated by a recent experiment on insulin microsphere formation where polyethylene glycol (PEG) is used as the precipitating agent, we have developed a simple theoretical model that can predict the formation of a fractal network of insulin monomers and the subsequent break-up of the fractal network into microsphere aggregates. In our approach the effect of PEG on insulin is modeled via a standard depletion attraction mechanism via the Asakura-Oosawa model. We show that even in the context of this simple model, it is possible to mimic important aspects of the insulin experiment in a brownian dynamics simulation. We simulate the effect of changing temperature in our model by changing the well depth of the Asakura-Oosawa potential. A fractal network is observed in a "deep quench" of the system, followed by a "heating" that results in a break-up of the network and subsequent formation of microspheres.

  11. LEBU drag reduction in high Reynolds number boundary layers. [Large Eddy Break-Up

    Science.gov (United States)

    Anders, J. B.

    1989-01-01

    Conventional and inverted, outer-layer leading-edge breakup devices (LEBUs) were water tunnel tested on an axisymmetric body over the Re number range from 380,000 to 3.8 million. Test results indicate a sharp degradation of the LEBUs' drag-reduction mechanism with increasing Re number. The most likely result of this degradation is a decoupling of the inner and outer scales at higher Re numbers; due to this decoupling, the breakup of the large structures by outer-layer devices has minimal influence on the near-wall, shear-producing scales. This suggests that smaller devices, closer to the walls, may be required for operation at elevated Re numbers.

  12. Sub-picosecond pulse break-up in an InGaAsP optical amplifier

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal

    For high-speed optical communication systems with data speed higher than 200 Gb/s sub-picosecond pulse dynamics, coherent effects become important. We have, experimentally and theoretically, investigated the pulse distortion of a 150 fs pulse due to amplification in a 250 μm long InGaAsP ridge...... broadening and eventual break-up for input pulse energies on the order of picoJoules. This break-up is present in the gain region (6-14 dB), while for absorption (-6 dB9 and transparency, pulse narrowing by a factor of two is evidenced. We observe that not only the amplitude is modulated, but also the linear...

  13. Sub-picosecond pulse break-up in an InGaAsP optical amplifier

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal

    1999-01-01

    For high speed optical communication system with data speed higher than 200 Gb/s sub-picosecond pulse dynamics, coherent effects become important.We have, experimentally and theoretically, investigated the pulse distortion of an 150 fs pulse due to amplification in a 250 ìm long InGaAsP ridge...... broadening and eventual break-up for input pulse energies on the order of picoJoules. This break-up is present in the gain region (6-14 dB), while for absorption (-6 dB) and transparency, pulse narrowing by a factor of two is evidenced. We observe that not only the amplitude is modulated, but also the linear...

  14. Characteristics of satellite breakups from radar cross section and plane change angle

    Science.gov (United States)

    Badhwar, Gautam D.; Potter, Andrew E.; Anz-Meador, Philip D.; Reynolds, Robert C.

    1988-01-01

    A problem of considerable interest in orbital debris research is the determination of the cause of the fragmentation of a satellite from the observed radar cross section and orbital element data. In this paper, analytic representations of the observed distribution functions of the radar cross section and the orbital plane change angle are derived. This then allows for the extraction of a small number of features that describe the observed data. Based on the known cause of fragmentation of a subset of satellites, a linear classifier is trained on these derived features. The discriminant function derived from this training is used to determine the previously unknown cause of the satellite breakup. the technique developed is objective and has been applied to the study of the cause of a number of unknown satellite breakup events.

  15. Effects of Ambient Gas Pressure on the Breakup of Sprays in Like-Doublet and Swirl Coaxial Injectors

    National Research Council Canada - National Science Library

    Yoon, Youngbin; Jeung, In-Seuk

    2004-01-01

    .... Two regimes are found: outer mixing injection and emulsion injection. In the case of single inner oxidizer spray, the spray angle and breakup length decrease as the ambient chamber pressure increases...

  16. Study of Ground State Wave-function of the Neutron-rich 29,30Na Isotopes through Coulomb Breakup

    Science.gov (United States)

    Rahaman, A.; Datta Pramanik, U.; Aumann, T.; Beceiro, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chakraborty, S.; Chatterjee, S.; Chartier, M.; De Angelis, G.; Cortina-Gil, D.; Gonzalez-Diaz, D.; Emling, H.; Diaz Fernandez, P.; Fraile, L. M.; Ershova, O.; Geissel, H.; Heil, M.; Jonson, B.; Kelic, A.; Johansson, H.; Kruecken, R.; Kroll, T.; Kurcewicz, J.; Langer, C.; Bleis, T. Le; Leifels, Y.; Munzenberg, G.; Marganiec, J.; Nociforo, C.; Najafi, A.; Panin, V.; Paschalis, S.; Pietri, S.; Plag, R.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Ray, J.; Simon, H.; Scheidenberge, C.; Typel, S.; Taylor, J.; Togano, Y.; Volkov, V.; Weick, H.; Wagner, A.; Wamers, F.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2014-03-01

    Coulomb breakup of unstable neutron rich nuclei 29,30Na around the `island of inversion' has been studied at energy around 434 MeV/nucleon and 409 MeV/nucleon respectively. Four momentum vectors of fragments, decay neutron from excited projectile and γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence. For these nuclei, the low-lying dipole strength above one neutron threshold can be explained by direct breakup model. The analysis for Coulomb breakup of 29,30Na shows that large amount of the cross section yields the 28Na, 29Na core in ground state. The predominant ground-state configuration of 29,30Na is found to be 28Na(g.s)⊗νs1/2 and 29Na(g.s)⊗νs1/2,respectively.

  17. Study of Ground State Wave-function of the Neutron-rich 29,30Na Isotopes through Coulomb Breakup

    Directory of Open Access Journals (Sweden)

    Rahaman A.

    2014-03-01

    Full Text Available Coulomb breakup of unstable neutron rich nuclei 29,30Na around the ‘island of inversion’ has been studied at energy around 434 MeV/nucleon and 409 MeV/nucleon respectively. Four momentum vectors of fragments, decay neutron from excited projectile and γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence. For these nuclei, the low-lying dipole strength above one neutron threshold can be explained by direct breakup model. The analysis for Coulomb breakup of 29,30Na shows that large amount of the cross section yields the 28Na, 29Na core in ground state. The predominant ground-state configuration of 29,30Na is found to be 28Na(g.s⊗νs1/2 and 29Na(g.s⊗νs1/2,respectively.

  18. Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity

    Science.gov (United States)

    Fenton, Flavio H.; Cherry, Elizabeth M.; Hastings, Harold M.; Evans, Steven J.

    2002-09-01

    It has become widely accepted that the most dangerous cardiac arrhythmias are due to reentrant waves, i.e., electrical wave(s) that recirculate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, have made it extremely difficult to pinpoint the detailed dynamics of these life-threatening reentrant arrhythmias. A simplified ionic model of the cardiac action potential (AP), which can be fitted to a wide variety of experimentally and numerically obtained mesoscopic characteristics of cardiac tissue such as AP shape and restitution of AP duration and conduction velocity, is used to explain many different mechanisms of spiral wave breakup which in principle can occur in cardiac tissue. Some, but not all, of these mechanisms have been observed before using other models; therefore, the purpose of this paper is to demonstrate them using just one framework model and to explain the different parameter regimes or physiological properties necessary for each mechanism (such as high or low excitability, corresponding to normal or ischemic tissue, spiral tip trajectory types, and tissue structures such as rotational anisotropy and periodic boundary conditions). Each mechanism is compared with data from other ionic models or experiments to illustrate that they are not model-specific phenomena. Movies showing all the breakup mechanisms are available at http://arrhythmia.hofstra.edu/breakup and at ftp://ftp.aip.org/epaps/chaos/E-CHAOEH-12-039203/ INDEX.html. The fact that many different breakup mechanisms exist has important implications for antiarrhythmic drug design and for comparisons of fibrillation experiments using different species, electromechanical uncoupling drugs, and initiation protocols.

  19. Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle

    OpenAIRE

    Oriolo, Sebastián; Oyhantçabal, Pedro; Wemmer, Klaus; Siegesmund, Siegfried

    2017-01-01

    Geological, geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed for the period 800–700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. These cratons occupied a marginal position in the southern hemisphere with respect to Rod...

  20. Doomsday for the Euro Area: Causes, Variants and Consequences of Breakup

    Directory of Open Access Journals (Sweden)

    Ansgar Belke

    2012-07-01

    Full Text Available In this paper we describe the genesis of a doomsday scenario and discuss potential causes and motivations for a breakup of the euro area. For this purpose, we differentiate between the departure of weak and strong countries, and examine the impact of the reintroduction of a national currency on domestic debt, the domestic banking sector, EU membership and the freedom of trade. We also briefly analyze the social and political costs of the accompanying social disorder.

  1. Digital image communication scheme based on the breakup of spiral waves

    Science.gov (United States)

    Vaidelys, Martynas; Lu, Chen; Cheng, Yujie; Ragulskis, Minvydas

    2017-02-01

    A digital image communication scheme based on the breakup of spiral waves is presented in this paper. This communication system does not require spatially homogeneous random initial conditions. Moreover, the secret image is not embedded into the initial conditions of the evolving self-organizing patterns. Such features increase the security of the communication, but still enable an effective transmission of the secret image. Computational experiments are used to demonstrate the properties and efficiency of the proposed scheme.

  2. Jet break-up in nano-suspensions during electrohydrodynamic atomization in the stable cone-jet mode.

    Science.gov (United States)

    Jayasinghe, S N; Edirisinghe, M J

    2005-06-01

    This paper reports jet break-up phenomena, which occurs during the electrohydrodynamic atomization (EHDA) of nano-suspensions. We investigated three ethylene glycol-based near-monodisperse suspensions, containing 30 wt% of SiO2 particles sized at 20, 80 and 120 nm. These suspensions were subjected to electrohydrodynamic atomization in the stable cone-jet mode and the jet break-up in each is discussed and compared with those of liquids reported in the literature.

  3. The NASA Ames Hypervelocity Free Flight Aerodynamic Facility: Experimental Simulation of the Atmospheric Break-Up of Meteors

    Science.gov (United States)

    Wilder, M. C.; Bogdanoff, D. W.

    2015-01-01

    The Hypervelocity Free Flight Aerodynamic Facility at NASA Ames Research Center provides a potential platform for the experimental simulation of meteor breakup at conditions that closely match full-scale entry condition for select parameters. The poster describes the entry environment simulation capabilities of the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center and provides example images of the fragmentation of a hypersonic projectile for which break-up was initiated by mechanical forces (impact with a thin polymer diaphragm).

  4. Breakup of a Liquid Drop Falling Through a Quiescent Media: A DNS Study

    Science.gov (United States)

    Jalaal, Maziyar; Mehravaran, Kian

    2011-11-01

    The breakup of falling liquid droplets in a stationary media is studied using Direct Numerical Simulations (DNS). An adaptive Volume of Fluid (VOF) method based on an octree Cartesian grid generation is employed, considerably reducing the computational cost. Fragmentations are followed reaching approximately stable clouds of droplets up to 1/1000 of the initial droplet diameter. Three different simulations are performed investigating the influence of the initial Eötvös number. The mechanism of breakup, one of the most unclear phenomena in multiphase systems is described in detail. The wave growth over the bag, creation and retraction of punctures and ligament formation are presented and results are compared with recent theoretical investigations of (Savva & Bush, J. Fluid. Mech.626: 211-240.) and (Bermond & Villermaux, J. Fluid. Mech.524: 121-130.). The roles of Rayleigh-Taylor and Rayleigh-Plateau instabilities on breakup are also described and their influences on further cluster-of-fragments creation are shown. The outcomes can be used to develop current secondary atomization models. Moreover, the results can be used for better understanding of rain drop atomization during precipitation, as well as water droplet atomization in cooling towers.

  5. Breakup Behavior of a Capillary Bridge on a Hydrophobic Stripe Separating Two Hydrophilic Stripes

    Science.gov (United States)

    Hartmann, Maximilian; Hardt, Steffen

    2017-11-01

    The breakup dynamics of a capillary bridge on a hydrophobic area between two liquid filaments occupying two parallel hydrophilic stripes is studied experimentally. In addition calculations with the finite-element software Surface Evolver are performed to obtain the corresponding stable minimal surfaces. Droplets of de-ionized water are placed on substrates with alternating hydrophilic and hydrophobic stripes of different width. Their volume decreases by evaporation. This results in a droplet shaped as the letter ``H'' covering two hydrophilic stripes separated by one hydrophobic stripe. The width of the capillary bridge d(t) on the hydrophobic stripe during the breakup process is observed using a high-speed camera mounted on a bright-field microscope. The results of the experiments and the numerical studies show that the critical width dcrit, indicating the point where the capillary bridge becomes unstable, mainly depends on the width ratio of the hydrophilic and hydrophobic stripes. It is found that the time derivative of d(t) first decreases after dcrit has been reached. The final breakup dynamics then follows a t 2 / 3 scaling. We kindly acknowledge the financial support by the German Research Foundation (DFG) within the Collaborative Research Centre 1194 ``Interaction of Transport and Wetting Processes'', Project A02a.

  6. The absence of a dense potential core in supercritical injection: A thermal break-up mechanism

    Science.gov (United States)

    Banuti, Daniel T.; Hannemann, Klaus

    2016-03-01

    Certain experiments in quasi-isobaric supercritical injection remain unexplained by the current state of theory: Without developing a constant value potential core as expected from the mechanical view of break-up, density is observed to drop immediately upon entering the chamber. Furthermore, this phenomenon has never been captured in computational fluid dynamics (CFD) despite having become a de facto standard case for real fluid CFD validation. In this paper, we present strong evidence for a thermal jet disintegration mechanism (in addition to classical mechanical break-up) which resolves both the theoretical and the computational discrepancies. A new interpretation of supercritical jet disintegration is introduced, based on pseudo-boiling, a nonlinear supercritical transition from gas-like to liquid-like states. We show that thermal disintegration may dominate classical mechanical break-up when heat transfer takes place in the injector and when the fluid state is sufficiently close to the pseudo-boiling point. A procedure which allows to capture subsided cores with standard CFD is provided and demonstrated.

  7. A Southern Hemisphere origin for campanulid angiosperms, with traces of the break-up of Gondwana.

    Science.gov (United States)

    Beaulieu, Jeremy M; Tank, David C; Donoghue, Michael J

    2013-04-08

    New powerful biogeographic methods have focused attention on long-standing hypotheses regarding the influence of the break-up of Gondwana on the biogeography of Southern Hemisphere plant groups. Studies to date have often concluded that these groups are too young to have been influenced by these ancient continental movements. Here we examine a much larger and older angiosperm clade, the Campanulidae, and infer its biogeographic history by combining Bayesian divergence time information with a likelihood-based biogeographic model focused on the Gondwanan landmasses. Our analyses imply that campanulids likely originated in the middle Albian (~105 Ma), and that a substantial portion of the early evolutionary history of campanulids took place in the Southern Hemisphere, despite their greater species richness in the Northern Hemisphere today. We also discovered several disjunctions that show biogeographic and temporal correspondence with the break-up of Gondwana. While it is possible to discern traces of the break-up of Gondwana in clades that are old enough, it will generally be difficult to be confident in continental movement as the prime cause of geographic disjunctions. This follows from the need for the geographic disjunction, the inferred biogeographic scenario, and the dating of the lineage splitting events to be consistent with the causal hypothesis.

  8. Tear film break-up time evaluated by real-time Hartmann-Shack wavefront sensing.

    Science.gov (United States)

    Mihashi, Toshifumi; Hirohara, Yoko; Koh, Shizuka; Ninomiya, Sayuri; Maeda, Naoyuki; Fujikado, Takashi

    2006-01-01

    To develop a novel method for measuring tear break-up time (BUT) by continuously measuring higher order wavefront aberrations using a Hartmann-Shack (H-S) aberrometer. Wavefront aberrations up to the sixth order for a 4-mm pupil were measured in six eyes of six normal subjects using an H-S aberrometer. The aberrometry was performed once every second for up to 50 s under topical anesthesia. The sequence of the points was divided into two stages, and the BUT was defined as the wavefront border of the stages (WFBUT). The WFBUT was compared with the BUT by the conventional fluorescein method (FLBUT) or by the disruption of placid-ring images (PLBUT). In three eyes, the WFBUT (average, 10.9 +/- 1.1 s) was shorter than the PLBUT (average, 17.5 +/- 2.5 s), while in the other three eyes the WFBUT (average, 21.5 +/- 2.2 s) was longer than PLBUT (average, 8.1 +/- 2.2 s). The FLBUT was shorter than WFBUT or PLBUT in most cases. The tear break-up time measured by H-S aberrometer may be used as a practical measure of tear break-up.

  9. Large-eddy simulation of cavitating nozzle flow and primary jet break-up

    Energy Technology Data Exchange (ETDEWEB)

    Örley, F., E-mail: felix.oerley@aer.mw.tum.de; Trummler, T.; Mihatsch, M. S.; Schmidt, S. J.; Adams, N. A. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Hickel, S. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Chair of Computational Aerodynamics, Faculty of Aerospace Engineering, TU Delft, Kluyverweg 1, 2629 HS Delft (Netherlands)

    2015-08-15

    We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.

  10. The effect of timolol maleate on tear film break-up time in Nigerians.

    Science.gov (United States)

    Fasina, O; Ashaye, A O; Ajayi, B G K

    2008-03-01

    The aim of this study was to evaluate the effect of Timolol maleate on tear film break-up time in a Nigerian population. 192 eyes of 96 subjects were examined in a hospital based case-control study after being administered pre-coded questionnaires. The mean tear film break-up time was measured. There was significant difference (t = 10.164, P break-up time of cases (10.45 secs) and controls (30.18 secs). Half of the cases had some ocular discomfort with the instillation of Timolol maleate, a significant number of them having just been commenced on the medication (chi2 = 8.889, P = 0.003). Long-term instillation of Timolol maleate impairs tear film stability. The ocular discomfort experienced by patients on Timolol may contribute to poor drug compliance observed in patients on chronic drug therapy. Regular screening of patients on Timolol maleate for tear film instability and dry eyes is important and drug manufacturers should explore the possibility of incorporating artificial tears in Timolol maleate preparation.

  11. On the evolution and breakup of slender drops in an extensional flow

    Science.gov (United States)

    Favelukis, M.; Lavrenteva, O. M.; Nir, A.

    2012-04-01

    The evolution of the shape of an elongated drop embedded in an extensional flow is studied in the framework of slender body theory. The external flow has a weak but not neglected inertia. The problem is governed by three dimensionless parameters: the capillary number, the external Reynolds number, and the viscosity ratio between the drop and the external fluid, and exhibits a multiplicity of stationary shapes with only one being stable. Evolution of the drop surface from initial shapes was studied when the flow intensity was either kept constant or subjected to a sudden change. It was shown that the dynamics of the shape evolution can lead to a breakup of the drop or to a stable stationary shape. Two modes of breakup are revealed: an indefinite elongation and a center pinching mode. The former appears when the viscous forces dominate the inertia effects, with the typical case being that of a creeping flow. The latter breakup mode takes over in the presence of inertia when the drop viscosity diminishes with the extreme example being that of an inviscid drop.

  12. Curvature Singularity in the Asymmetric Breakup of an Underwater Air Bubble

    CERN Document Server

    Lai, Lipeng

    2012-01-01

    The presence of slight azimuthal asymmetry in the initial shape of an underwater bubble entirely alters the final breakup dynamics. Here I examine the influence of initial asymmetry on the final breakup by simulating the bubble surface evolution as a Hamiltonian evolution corresponding to an inviscid, two-dimensional, planar implosion. I find two types of breakups: a previously reported coalescence mode in which distant regions along the air-water surface curve inwards and eventually collide with finite speed, and a hitherto unknown cusp-like mode in which the surface develops sharp tips whose radii of curvature are much smaller than the average neck radius. I present three sets of results that characterize the nature of this cusp mode. First, I show that the cusp mode corresponds to a saddle-node. In other words, an evolution towards a cross-section shape with sharp tips invariably later evolves away from it. In phase space, this saddle-node separates coalescence modes whose coalescence planes lie along diff...

  13. Thermal instabilities and Rayleigh breakup of ultrathin silver nanowires grown in helium nanodroplets.

    Science.gov (United States)

    Volk, Alexander; Knez, Daniel; Thaler, Philipp; Hauser, Andreas W; Grogger, Werner; Hofer, Ferdinand; Ernst, Wolfgang E

    2015-10-14

    Ag nanowires with diameters below 6 nm are grown within vortex containing superfluid helium nanodroplets and deposited onto a heatable substrate at cryogenic temperatures. The experimental setup allows an unbiased investigation of the inherent stability of pristine silver nanowires, which is virtually impossible with other methods due to chemical processes or templates involved in standard production routes. We demonstrate by experiment and by adaption of a theoretical model that initially continuous wires disintegrate into chains of spheres. This phenomenon is well described by a Rayleigh-like breakup mechanism when the substrate is heated to room temperature. Our findings clarify the recent discussions on the cause of the observed segmented patterns, where a breakup during deposition [Gomez et al., Phys. Rev. Lett., 2012, 108, 155302] or mechanisms intrinsic to the helium droplet mediated growth process [Spence et al., Phys. Chem. Chem. Phys., 2014, 16, 6903] have been proposed. The experimental setup confirms the validity of previous suggestions derived from bulk superfluid helium experiments [Gordon et al., Phys. Chem. Chem. Phys., 2014, 16, 25229] for the helium droplet system, and further allows a much more accurate determination of the breakup temperature.

  14. Two-Branch Break-up Systems by a Single Mantle Plume: Insights from Numerical Modeling

    Science.gov (United States)

    Beniest, A.; Koptev, A.; Leroy, S.; Sassi, W.; Guichet, X.

    2017-10-01

    Thermomechanical modeling of plume-induced continental break-up reveals that the initial location of a mantle anomaly relative to a lithosphere inhomogeneity has a major impact on the geometry and timing of a rift-to-spreading system. Models with a warmer Moho temperature are more likely to result in "plume-centered" mode, where the rift and subsequent spreading axis grow directly above the plume. Models with weak far-field forcing are inclined to develop a "structural-inherited" mode, with lithosphere deformation localized at the lateral lithospheric boundary. Models of a third group cultivate two break-up branches (both "plume-centered" and "structural inherited") that form consecutively with a few million years delay. With our experimental setup, this break-up mode is sensitive to relatively small lateral variations of the initial anomaly position. We argue that one single mantle anomaly can be responsible for nonsimultaneous initiation and development of two rift-to-spreading systems in a lithosphere with a lateral strength contrast.

  15. Visualization of the drop deformation and break-up process in a high pressure homogenizer

    Energy Technology Data Exchange (ETDEWEB)

    Innings, F. [Tetra Pak Processing Systems, Ruben Rausings gata, SE-221 86 Lund (Sweden); Traegaardh, C. [Lund University, Box 124, SE-221 00 Lund (Sweden)

    2005-08-01

    For the creation of sub-micron emulsions in fluids of low viscosity the high pressure homogenizer (HPH) is usually chosen. One way of obtaining deeper knowledge of exactly what happens in the active region is to visualize it. In this work, a drop deformation and break-up visualization system based on a modified Particle Image Velocimetry (PIV) system is described. The system reproduces the gap in a HPH and has been used with pressures up to 18 MPa and drops as small as 5 {mu}m. The optics of the system are analyzed taking into account limiting factors such as the lens resolving power, the focal depth, and the duration of the laser pulses. It is shown that it is possible to resolve drops down to a few {mu}m moving in excess of 100 m/s, and that the main limitations are the resolving power and in the focal depth of the objectives. Examples are shown from capillary drop creation and from the deformation and break-up of drops in a HPH. It can be concluded that in a HPH, the drops are only deformed to a limited extent in the inlet of the gap, and that all drop break-up occurs far downstream of the gap. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  16. Effect of contact line motion on the deformation and breakup of stretching liquid bridges

    Science.gov (United States)

    Ambravaneswaran, B.; Panditaratne, J. C.; Schreiweis, A. L.; Basaran, O. A.

    1999-11-01

    The use of pin-tools for the deposition of small quantities of liquids on substrates has gained popularity recently. Applications range from spotting of biochips in DNA arrayers to coloring of contact lenses. The pin-tool is nothing more than a stretching liquid bridge whose contact lines are allowed to move on one or both of the substrates between which the bridge liquid is held captive. In this paper, the effect of contact line motion on the stretching and breakup of the liquid bridge is analyzed. The movement of the contact line is modeled by means of Navier's slip law and a constant contact angle. In the computations, the full nonlinear, transient Navier-Stokes system is solved using the Galerkin/finite element method. The experiments rely on the use of high-speed digital imagers for visualization of the contact line motion and dynamics of bridge breakup. The partitioning of the liquid between the two substrates and the size of the spots formed on the substrates upon bridge breakup are determined as functions of the physical and the geometric properties of the bridge-substrate system and stretching velocity.

  17. Effects of soluble surfactants on the deformation and breakup of stretching liquid bridges.

    Science.gov (United States)

    Liao, Ying-Chih; Subramani, Hariprasad J; Franses, Elias I; Basaran, Osman A

    2004-11-09

    Surfactants are routinely used to control the breakup of drops and jets in many applications such as inkjet printing, crop spraying, and DNA or protein microarraying. The breakup of surfactant-free drops and jets has been extensively studied. By contrast, little is known about the closely related problem of interface rupture when surfactants are present. Solutions of a nonionic surfactant, pentaethylene glycol monododecyl ether, or C12E5, in water and in 90 wt % glycerol/water are used to show the effects of surfactant and viscosity on the deformation and breakup dynamics of stretching liquid bridges. Equilibrium surface tensions for both solutions can be fitted with the Langmuir-Szyskowski equation. All experiments have been done at 24 degrees C. The critical micelle concentrations for C12E5 are 0.04 and 0.4 mM in water and the glycerol/water solution, respectively. With high-speed imaging, the dynamic shapes of bridges held captive between two rods of 3.15 mm diameter are captured and analyzed with a time resolution of 0.1-1 ms. The bridge lengths are 3.15 mm initially and about 5-7 mm at pinch-off. Breakup occurs after stretching for about 0.2-0.3 s, depending on the solution viscosity and the surfactant concentration. When the liquid bridges break up, the volume of the sessile drop left on the bottom rod is about 3 times larger than that of the pendant drop left on the top rod. This asymmetry is due to gravity and is influenced by the equilibrium surface tensions. Surfactant-containing low-viscosity water bridges are shown to break up faster than surfactant-free ones because of the effect of gravity. With or without surfactant, water bridges form satellite drops. Surfactant-containing high-viscosity glycerol/water bridges break up more slowly than surfactant-free ones because of strong viscous effects. Moreover, the shapes of the sessile drops close to breakup exhibit a "pear-like" tip; whether a satellite forms depends on the surface age of the bridge before

  18. Low and medium energy deuteron-induced reactions on Cu63,65 nuclei

    Science.gov (United States)

    Šimečková, E.; Bém, P.; Honusek, M.; Štefánik, M.; Fischer, U.; Simakov, S. P.; Forrest, R. A.; Koning, A. J.; Sublet, J.-C.; Avrigeanu, M.; Roman, F. L.; Avrigeanu, V.

    2011-07-01

    The activation cross sections of (d,p), (d,2n), (d,3n), and (d,2p) reactions on Cu63,65 were measured in the energy range from 4 to 20 MeV using the stacked-foil technique. Then, following the available elastic-scattering data analysis that provided the optical potential for reaction cross-section calculations, an increased effort was devoted to the breakup mechanism, direct reaction stripping, and pre-equilibrium and compound-nucleus cross-section calculations, corrected for the breakup and stripping decrease of the total reaction cross section. The overall agreement between the measured and calculated deuteron activation cross sections proves the correctness of the nuclear mechanism account, next to the simultaneous analysis of the elastic-scattering and reaction data.

  19. One-neutron stripping reactions of 11Be and 19C on light target

    Indian Academy of Sciences (India)

    We have calculated the one-neutron absorption cross-section and the longitudinal momentum distribution of the core fragment coming out from the breakup of 11Be and 19C on 9Be target at 63 MeV/A and 88 MeV/A beam energies respectively. The reaction mechanism is treated within the framework of the eikonal ...

  20. The 2H(e, e' p)n reaction at large energy transfers

    NARCIS (Netherlands)

    Willering, Hendrik Willem

    2003-01-01

    At the ELSA accelerator facillity in Bonn, Germany, we have measured the deutron "breakup" reaction 2H(e,e' p)n at four-momentum transfers around Q2 = -0 .20(GeV/c)2 with an electron beam energy of E0 = 1.6 GeV. The cross section has been determined for energy transfers extending from the

  1. Elastic scattering and fusion cross-sections in Li + Al reaction

    Indian Academy of Sciences (India)

    Abstract. With an aim to understand the effects of breakup and transfer channels on elastic scat- tering and fusion cross-sections in the 7Li + 27Al reaction, simultaneous measurement of elastic scattering angular distributions and fusion cross-sections have been carried out at various energies. (Elab = 8.0–16.0 MeV) around ...

  2. Numerical Analysis of the Primary Breakup Applying the Embedded DNS Approach to a Generic Prefilming Airblast Atomizer

    Directory of Open Access Journals (Sweden)

    Benjamin Sauer

    2014-09-01

    Full Text Available An improved understanding of the breakup processes of two-phase flows is essential to effectively control the fuel atomization for future aircraft engines. A detailed insight into the phenomena of primary breakup is a major limitation in gaining this knowledge. Aircraft engines use airblast atomizers to provide the fuel atomization. The geometries of airblast atomizers are complex, the operating conditions are characterized by high Reynolds- and Weber numbers. Direct Numerical Simulations (DNS of liquid breakup under realistic conditions and geometries are hardly possible. The embedded DNS (eDNS concept aims to fill this gap. The concept consists of three steps: a geometry simplification, the generation of realistic boundary conditions for the DNS and the DNS of the breakup region. The realistic annular airblast atomizer geometry is simplified to a planar geometry. Inside this domain the eDNS is located. The eDNS domain requires the generation of boundary conditions. A zonal Large Eddy Simulation (LES of the turbulent channel flow is performed prior to the DNS. The parameters are stored transiently on the “virtual” DNS inlet planes. These variables are then mapped to the DNS. The Volume of fluid (VOF method is used to solve for the two-phase flow. DNS are performed for a shear-driven liquid wall film and for a generic planar prefilming airblast atomizer. As the Reynolds and Weber number for the first operating point (OP are low (Reair = 5,333/Wefilm = 1.9, the liquid wall film as well as the liquid sheet show no surface waves. For the second case with Reair = 13,333 and We film = 11.9, the surface appears more wrinkled and streamwise waves are transported along the wall for the shear-driven wall film. Instantaneous snapshots in 2–D and 3–D illustrate the qualitative behavior of the liquid sheet in time. Leaving the prefilmer trailing edge, the liquid sheet starts to oscillate in a sinusoidal fashion. This oscillation appears crucial for

  3. Study of reactions induced by 6He on 9Be

    Directory of Open Access Journals (Sweden)

    Pires K.C.C.

    2014-03-01

    Full Text Available We present the results of experiments using a 6He beam on a 9Be target at energies 7 − 9 times the Coulomb barrier. Angular distributions of the elastic, inelastic scattering (target breakup and the a-particle production in the 6He+9Be collision have been analysed. Total reaction cross sections were obtained from the elastic scatteringanalyses and a considerable enhancement has been observed by comparing to stable systems.

  4. Experimental investigation of hysteresis in the break-up of liquid curtains

    KAUST Repository

    Marston, Jeremy

    2014-09-01

    Findings from an experimental investigation of the break-up of liquid curtains are reported, with the overall aim of examining stability windows for multi-layer liquid curtains composed of Newtonian fluids, where the properties of each layer can be kept constant or varied. For a single-layer curtain it is known that the minimum flow rate required for initial stability can be violated by carefully reducing the flow rate below this point, which defines a hysteresis region. However, when two or three layers are used to form a composite curtain, the hysteresis window can be considerably reduced depending on the experimental procedure used. Extensive quantitative measurements of this hysteresis region are provided alongside an examination of the influence of physical properties such as viscosity and surface tension. The origins of curtain break-up for two different geometries are analysed; first where the curtain width remains constant, pinned by straight edge guides; and second where the curtain is tapered by angled edge guides. For both cases, the rupture speed is measured, which appears to be consistent with the Taylor-Culick velocity. Observations of the typical linearly spaced jets which form after the break-up has transpired and the periodicity of these jets are compared to the Rayleigh-Taylor wavelength and previous experimental measurements. Furthermore, the curtain stability criterion originally developed by Brown (1961), summarised in terms of a Weber number, has recently been extended to multi-layer curtains by Dyson et al. (2009); thus this report provides the first experimental measurements which puts this to the test. Ultimately, it is found that only the most viscous and polymer-based liquids violate this criterion. © 2014 Elsevier Ltd.

  5. Solving the three-body Coulomb breakup problem using exterior complex scaling

    Energy Technology Data Exchange (ETDEWEB)

    McCurdy, C.W.; Baertschy, M.; Rescigno, T.N.

    2004-05-17

    Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a ''reduction to computation'' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations, and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wave function can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.

  6. Analysis of a gas stratification break-up by a vertical jet using the GOTHIC code

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Cosials, Mikel Kevin; Jimenez, Gonzalo, E-mail: gonzalo.jimenez@upm.es; Lopez-Alonso, Emma

    2016-02-15

    Highlights: • Study of a light gas distribution with the GOTHIC code based on the OECD/NEA IBE-3. • Sensitivity analysis on turbulence model, discretization scheme and heat transfer. • The jet erosion phenomena is captured properly with a relatively coarse mesh. • Development of a tool to evaluate the influence of each parameter on the simulation. • Several recommendation on modeling a stratification break-up are included. - Abstract: During a severe accident in light water reactor (LWR), hydrogen concentration can overpass the flammability limits locally, so the correct simulation of its behavior during a release is critical. The capability assessment of computational fluid dynamics tools to calculate the hydrogen distribution under different conditions has been the focus of intense research worldwide. In this context, the OECD/NEA conducted an international benchmark exercise (IBE-3), which was focused on the break-up of a stratified layer of a light gas by a vertical jet. The participants performed their simulations before the experiment data was released. When the data was released, it was noticed that a combination of several parameters like the mesh, turbulence model or solver controls were responsible for the broad differences between the participants’ results. To obtain information about how each parameter affects the simulation, a post-test sensitivity analysis has been done by the UPM. In this paper, the IBE-3 experiment simulation with GOTHIC 8.0 is presented along with extensive sensitivity analyses of the relevant parameters. The first objective of the work is to test the capability of GOTHIC 8.0 to simulate properly a gas stratification break-up by a vertical jet with a relatively coarse mesh. The second objective of the paper is to relate each sensitivity parameter with each other and with the experiment through the Parameter Influence Chart, a helpful tool specially designed for this purpose.

  7. Microfluidic Generation of High-Viscosity Droplets by Surface-Controlled Breakup of Segment Flow.

    Science.gov (United States)

    Chen, Haosheng; Man, Jia; Li, Zhongnan; Li, Jiang

    2017-06-28

    Fluids containing high concentration polymers, sols, nanoparticles, etc., usually have high viscosities, and high-viscosity fluids are difficult to be encapsulated into uniform droplets. Here we report a surface-controlled breakup method to generate droplets directly from various aqueous and nonaqueous fluids with viscosities of 1.0 to 11.9 Pa s and a dispersed-to-continuous viscosity ratio up to 1000, whereas the volume fraction of droplets up to 50% can be achieved. It provides a straightforward method to encapsulate high viscosity fluids, in a well-controlled manner in the rapid developing droplet-based applications, including materials synthesis, drug delivery, cell assay, bioengineering, etc.

  8. Comparison of axial and radial electron beam-breakup transit-time oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, T.J.T. [Los Alamos National Lab., NM (United States); Mostrom, M.A. [Mission Research Corporation, Albuquerque, NM (United States)

    1995-08-01

    Comparison of two configurations of a novel high-power microwave generator is presented in this article. Coupling the beam-breakup instability with the transit-time effect of the electron beam in the cavity, rapid energy exchange between the electrons and cavity modes can occur. The dominant cavity modes in the axial and radial configurations are different but their growth rates are comparable. We found that the radial configuration can have a beam impedance less than 10 {Omega} and therefore more suitable for low-voltage and high power operation. Good agreements have been obtained between linear theory and simulation for both configurations.

  9. The breakup of Old English to-infinitive: Causes and consequences

    OpenAIRE

    Jarad, Najib Ismail

    2010-01-01

    The main goal of this paper is to account for the recategorisation of the Old English to-infinitive and the consequent rise of for before the Middle English to-infinitive. We argue that the loss of D feature has two consequences. The first consequence is that V+Inf-to-D movement was lost resulting in the break-up of the (morphological and) syntactic unity of the to-infinitive. The second consequence, a consequence of the first consequence, concerns the appearance of the so-called ...

  10. Asymmetric rifting, breakup and magmatism across conjugate margin pairs: insights from Newfoundland to Ireland

    Science.gov (United States)

    Peace, Alexander L.; Welford, J. Kim; Foulger, Gillian R.; McCaffrey, Ken J. W.

    2017-04-01

    Continental extension, subsequent rifting and eventual breakup result in the development of passive margins with transitional crust between extended continental crust and newly created oceanic crust. Globally, passive margins are typically classified as either magma-rich or magma-poor. Despite this simple classification, magma-poor margins like the West Orphan Basin, offshore Newfoundland, do exhibit some evidence of localized magmatism, as magmatism to some extent invariably accompanies all continental breakup. For example, on the Newfoundland margin, a small volcanic province has been interpreted near the termination of the Charlie Gibbs Fracture Zone, whereas on the conjugate Irish margin within the Rockall Basin, magmatism appears to be more widespread and has been documented both in the north and in the south. The broader region over which volcanism has been identified on the Irish margin is suggestive of magmatic asymmetry across this conjugate margin pair and this may have direct implications for the mechanisms governing the nature of rifting and breakup. Possible causes of the magmatic asymmetry include asymmetric rifting (simple shear), post-breakup thermal anomalies in the mantle, or pre-existing compositional zones in the crust that predispose one of the margins to more melting than its conjugate. A greater understanding of the mechanisms leading to conjugate margin asymmetry will enhance our fundamental understanding of rifting processes and will also reduce hydrocarbon exploration risk by better characterizing the structural and thermal evolution of hydrocarbon bearing basins on magma-poor margins where evidence of localized magmatism exists. Here, the latest results of a conjugate margin study of the Newfoundland-Ireland pair utilizing seismic interpretation integrated with other geological and geophysical datasets are presented. Our analysis has begun to reveal the nature and timing of rift-related magmatism and the degree to which magmatic asymmetry

  11. Force Required to Breakup a Continent: Implications on Rifting Localization and Migration

    Science.gov (United States)

    Svartman Dias, A. E.; Lavier, L. L.; Hayman, N. W.

    2014-12-01

    The maximum force from ridge push available is about 5 TN/m, lower than that required by 2D and 3D numerical experiments to rift the lithosphere in the absence of magmatic input. We carry out 2D numerical experiments without any magmatic input to study the extensional force necessary to start a rift basin and to breakup a continent. We assume a range of initial temperature structure, crust and mantle initial thicknesses and composition. In a first step, we use velocity boundary conditions (1cm/yr) and we monitor the force necessary to breakup the continent. Results can be classified in two groups according to the amount of force needed to rift through time: (1) The initial force builds up rapidly to 12-20 TN/m within 0.4-1.0 Myr. This is followed by an exponential decrease due to early strain localization and lithospheric weakening. The force is value of 3-5 TN/m from 0.4 Myr to 10 Myr, when strain starts localizing. The constant force through time reflects lithosphere strengthening and migration of the deformation. This rift migration forms a wide basin (> 250 km wide) that may evolve to form very asymmetric conjugate margins. Breakup occurs 18 Myr after the onset of rifting or later. This second group corresponds to experiments with initial Tmoho > 650 km and crustal thicknesses ≥ 35 km. High bending stresses result in upper crust brittle failure and on enhancement of lower crust lateral flow. Interaction between ductile failure in the lower crust and brittle failure in the upper crust controls the migration of the deformation. In a second step, we repeat the same experiments applying a constant extensional force ≤ 5 TN/m to test whether and how the limited ridge push force naturally available can rift and breakup a continent. We then compare our results to the evolution of aborted rifts and to along strike variations in rifted magins such as the South Atlantic.

  12. The Rockall Trough, NE Atlantic: An Extinct Young Ocean Basin or a Failed Breakup Basin?

    Science.gov (United States)

    Roberts, Alan; Kusznir, Nick; Alvey, Andy

    2017-04-01

    We investigate the crustal structure and composition of the Rockall Trough which is located in the NE Atlantic to the west of Ireland and the UK. The Rockall Trough is a large extensional basin formed in the Early Cretaceous and has dimensions of approximately 250 km in width and 1000 km in length. It is one of several basins formed during the complex Mesozoic northward propagation of rifting, continental breakup and sea-floor spreading initiation of the North Atlantic; other adjacent basins formed at this time include the Porcupine Trough to its east and the East and West Orphan Basins on the Canadian conjugate margin. To investigate the crustal structure of the Rockall Trough we have used three independent analyses of available 2D and 3D data: 1. 3D gravity inversion, using public-domain gravity and sediment-thickness information, has produced maps of (i) depth to Moho, (ii) crustal thickness (figure 1) and (iii) stretching/thinning factor across both margins. 2. Gravity inversion as above, but using public-domain gravity data combined with new proprietary 2D sediment-thickness information, has produced a series of cross-sections which show (i) depth to Moho, (ii) crustal thickness and (iii) stretching/thinning factor across both margins 3. Geodynamic modelling, comprising 2D flexural backstripping and forward modelling, has been used to produce (i) estimates of stretching/thinning factor, (ii) whole-crustal cross-sections and (iii) predictions of palaeobathymetry through time along a series of project-specific transects. Our analysis of the Rockall Trough shows a rapid shallowing of crustal basement thicknesses on the flanks of the basin with central values of crustal thickness typically 8-10 km consistent with previously published seismic estimates. An important question is whether this thin crust is hyper-extended continental crust or proto-oceanic crust. Locally isolated patches of crustal thicknesses as low as 3km are observed which are consistent with the

  13. Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle

    Directory of Open Access Journals (Sweden)

    Sebastián Oriolo

    2017-11-01

    Full Text Available Geological, geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed for the period 800–700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension, island arc development and limited formation of oceanic crust in internal oceans. This period was thus characterized by increased crustal growth in Western Gondwana, resulting from addition of juvenile continental crust along convergent margins. In contrast, crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana. The Río de la Plata, Congo-São Francisco, West African and Amazonian cratons collided at ca. 630–600 Ma along the West Gondwana Orogen. These events overlap in time with the onset of the opening of the Iapetus Ocean at ca. 610–600 Ma, which gave rise to the separation of Baltica, Laurentia and Amazonia and resulted from the final Rodinia break-up. The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca. 580 Ma, contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin. However, the Kalahari Craton was lately incorporated during the Late Ediacaran–Early Cambrian. The proposed Gondwana evolution rules out the existence of Pannotia, as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia. Additionally, a combination of introversion and extroversion is proposed for the assembly of Gondwana. The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the

  14. Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit

    Science.gov (United States)

    Pardini, Carmen

    On 11 January 2007, the 880 kg (958 kg at launch) weather spacecraft Fengyun-1C, launched on 10 May 1999 into a sun-synchronous orbit with a CZ-4B booster from the Taiyuan Satellite Launch Center, was destroyed over central China as a result of the first successful Chinese anti-satellite weapon test. It was carried out with a direct ascent interception with a kinetic energy kill vehicle launched by an SC-19 missile, fired from a mobile ground platform close to the Xichang Satellite Launch Center. While the technical details of the test, probably the third attempt, and the characteristics of the weapon used remain shrouded in secrecy, the intentional breakup of the aging weather spacecraft, fully functional until 2005, produced a huge amount of debris in one of the orbital regimes already most affected by past fragmentation events. At present, the US Space Surveillance Network has identified about 2600 objects, typically larger than 10 cm, but the fragments larger than 1 cm may be more than 100,000. After two decades of substantial international progress in the field of orbital debris mitigation, in order to preserve the low Earth and geosynchronous environments for future space missions, the Fengyun-1C destruction represented a serious turnabout. In fact, it abruptly increased by approximately 20% the number of cataloged debris in orbit. To give a rough idea of the impact of this single event on the circumterrestrial environment, it is sufficient to realize that about 15 years of global space activity - including failures and accidental breakups - had been needed to increase, by a comparable amount, the number of cataloged debris in orbit to the level observed before the Chinese anti-satellite test. The purpose of this presentation is to assess the impact of the debris cloud generated by the Fengyun-1C breakup on the low Earth environment. The anti-satellite test was carried out at an altitude of about 863 km, spreading the cataloged fragments between 200 and 4000

  15. Confinement and viscosity ratio effect on droplet break-up in a concentrated emulsion flowing through a narrow constriction.

    Science.gov (United States)

    Gai, Ya; Khor, Jian Wei; Tang, Sindy K Y

    2016-08-21

    This paper describes the dimensionless groups that determine the break-up probability of droplets in a concentrated emulsion during its flow in a tapered microchannel consisting of a narrow constriction. Such channel geometry is commonly used in droplet microfluidics to investigate the content of droplets from a concentrated emulsion. In contrast to solid wells in multi-well plates, drops are metastable, and are prone to break-up which compromises the accuracy and the throughput of the assay. Unlike single drops, the break-up process in a concentrated emulsion is stochastic. Analysis of the behavior of a large number of drops (N > 5000) shows that the probability of break-up increases with applied flow rate, the size of the drops relative to the size of the constriction, and the viscosity ratio of the emulsion. This paper shows that the break-up probability collapses into a single curve when plotted as a function of the product of capillary number, viscosity ratio, and confinement factor defined as the un-deformed radius of the drop relative to the hydraulic radius of the constriction. Fundamentally, the results represent a critical step towards the understanding of the physics governing instability in concentrated emulsions. Practically, the results provide a direct guide for the rational design of microchannels and the choice of operation parameters to increase the throughput of the droplet interrogation step while preserving droplet integrity and assay accuracy.

  16. Deformation and breakup of a non-Newtonian slender drop in an extensional flow: inertial effects and stability

    Science.gov (United States)

    Favelukis, Moshe; Lavrenteva, Olga M.; Nir, Avinoam

    2006-09-01

    We consider the deformation and breakup of a non-Newtonian slender drop in a Newtonian liquid, subject to an axisymmetric extensional flow, and the influence of inertia in the continuous phase. The non-Newtonian fluid inside the drop is described by the simple power-law model and the unsteady deformation of the drop is represented by a single partial differential equation. The steady-state problem is governed by four parameters: the capillary number; the viscosity ratio; the external Reynolds number; and the exponent characterizing the power-law model for the non-Newtonian drop. For Newtonian drops, as inertia increases, drop breakup is facilitated. However, for shear thinning drops, the influence of increasing inertia results first in preventing and then in facilitating drop breakup. Multiple stationary solutions were also found and a stability analysis has been performed in order to distinguish between stable and unstable stationary states.

  17. Cooperative breakups induced by drop-to-drop interactions in one-dimensional flows of drops against micro-obstacles.

    Science.gov (United States)

    Schmit, Alexandre; Salkin, Louis; Courbin, Laurent; Panizza, Pascal

    2015-03-28

    Depending on the capillary number at play and the parameters of the flow geometry, a drop may or may not break when colliding with an obstacle in a microdevice. Modeling the flow of one-dimensional trains of monodisperse drops impacting a micro-obstacle, we show numerically that complex dynamics may arise through drop-to-drop hydrodynamic interactions: we observe sequences of breakup events in which the size of the daughter drops created upon breaking mother ones becomes a periodic function of time. We demonstrate the existence of numerous bifurcations between periodic breakup regimes and we establish diagrams mapping the possible breakup dynamics as a function of the governing (physicochemical, hydrodynamic, and geometric) parameters. Microfluidic experiments validate our model as they concur very well with predictions.

  18. Infant mortality in Kyrgyzstan before and after the break-up of the Soviet Union.

    Science.gov (United States)

    Guillot, Michel; Lim, So-Jung; Torgasheva, Liudmila; Denisenko, Mikhail

    2013-01-01

    There is a great deal of uncertainty over the levels of, and trends in, infant mortality in the former Soviet republics of Central Asia. As a result, the impact of the break-up of the Soviet Union on infant mortality in the region is not known, and proper monitoring of mortality levels is impaired. In this paper, a variety of data sources and methods are used to assess levels of infant mortality and their trend over time in one Central Asian republic, Kyrgyzstan, between 1980 and 2010. An abrupt halt to an already established decline in infant mortality was observed to occur during the decade following the break-up of the Soviet Union, contradicting the official statistics based on vital registration. Infants of Central Asian ethnicity and those born in rural areas were also considerably more at risk of mortality than suggested by the official sources. We discuss the implications of these findings, both for health policy in this seldom studied part of the former Soviet Union and for our understanding of the health crisis which it currently faces.

  19. Liquid jet breakup and atomization in rocket chambers under dense spray conditions

    Science.gov (United States)

    Kuo, Kenneth K.; Cheung, Fan-Bill; Woodward, Roger D.; Garner, Kenneth N.

    1991-01-01

    Two advanced diagnostic techniques were established and employed in this project. The first technique involves the use of a real-time x ray radiography system along with a high-speed CCD Xybion camera and an advanced digital image processor to investigate the breakup processes of the liquid core. The focus of this part of the project is to determine the inner structure of the liquid jet and via thin sheets of laser light, with the scatters light being photographed by a Xybion electronic camera synchronized to the laser pulse. This technique, which is capable of recording the breakup event occurring within 25 nano-seconds, enables us to freeze the motions of the jet and liquid droplets. The focus of this part of the project is to determine the outer structure of the liquid jet and to discover the configuration of the surface waves, the spray pattern, and the droplet size distribution in the non-dilute region. Results obtained by these two advanced diagnostic techniques will provide the much needed database for model development and accurate prediction of engine performance. The present work also represents a breakthrough in the area of advanced diagnostics of dense sprays.

  20. Mechanisms, role of vorticity, and time scales for planar liquid sheet breakup

    Science.gov (United States)

    Zandian, Arash; Sirignano, William; Hussain, Fazle

    2016-11-01

    The 3D, temporal instabilities on a planar liquid sheet are studied using DNS with level-set and VoF surface tracking methods. λ2 contours relate the vorticity to the surface dynamics. The breakup character depends on the Ohnesorge number (Oh). At high Oh , hairpin vortices form on the braid and overlap with the lobe hairpins, thinning the lobes, which puncture creating holes and bridges. The bridges break, creating ligaments that stretch and break into droplets by capillary action. At low Oh , lobe stretching and thinning is hindered by high surface tension and splitting of the original Kelvin-Helmholtz vortex, preventing early hole formation. Corrugations form on the lobe edges, influenced by the split vortices, and stretch to form ligaments. Both mechanisms are present in a transition region that shifts in Oh values based on the liquid/gas density ratio. Different characteristic times exist for the hole formation and the lobe and ligament stretching, related to surface tension and liquid viscosity, respectively. In the transition region, both times are of the same order. Streamwise vorticity triggers the 3D instabilities. Vorticity stretching and baroclinicity dominate, while the spanwise and cross-flow vorticity tilting are less important early in the breakup.

  1. Pangea break-up: from passive to active margin in the Colombian Caribbean Realm

    Science.gov (United States)

    Gómez, Cristhian; Kammer, Andreas

    2017-04-01

    The break-up of Western Pangea has lead to a back-arc type tectonic setting along the periphery of Gondwana, with the generation of syn-rift basins filled with sedimentary and volcanic sequences during the Middle to Late Triassic. The Indios and Corual formations in the Santa Marta massif of Northern Andes were deposited in this setting. In this contribution we elaborate a stratigraphic model for both the Indios and Corual formations, based on the description and classification of sedimentary facies and their architecture and a provenance analysis. Furthermore, geotectonic environments for volcanic and volcanoclastic rock of both units are postulated. The Indios Formation is a shallow-marine syn-rift basin fill and contains gravity flows deposits. This unit is divided into three segments; the lower and upper segments are related to fan-deltas, while the middle segment is associated to offshore deposits with lobe incursions of submarine fans. Volcanoclastic and volcanic rocks of the Indios and Corual formations are bimodal in composition and are associated to alkaline basalts. Volcanogenic deposits comprise debris, pyroclastic and lava flows of both effusive and explosive eruptions. These units record multiple phases of rifting and reveal together a first stage in the break-up of Pangea during Middle and Late Triassic in North Colombia.

  2. Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification.

    Science.gov (United States)

    Lindskog, A; Costa, M M; Rasmussen, C M Ø; Connelly, J N; Eriksson, M E

    2017-01-24

    The catastrophic disruption of the L chondrite parent body in the asteroid belt c. 470 Ma initiated a prolonged meteorite bombardment of Earth that started in the Ordovician and continues today. Abundant L chondrite meteorites in Middle Ordovician strata have been interpreted to be the consequence of the asteroid breakup event. Here we report a zircon U-Pb date of 467.50±0.28 Ma from a distinct bed within the meteorite-bearing interval of southern Sweden that, combined with published cosmic-ray exposure ages of co-occurring meteoritic material, provides a precise age for the L chondrite breakup at 468.0±0.3 Ma. The new zircon date requires significant revision of the Ordovician timescale that has implications for the understanding of the astrogeobiologic development during this period. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated.

  3. Episodic Jurassic to Lower Cretaceous intraplate compression in Central Patagonia during Gondwana breakup

    Science.gov (United States)

    Navarrete, César; Gianni, Guido; Echaurren, Andrés; Kingler, Federico Lince; Folguera, Andrés

    2016-12-01

    From Lower Jurassic to Lower Cretaceous, several intraplate compression events affected discrete sectors of Central Patagonia, under a general context of crustal extension associated with Gondwana breakup. This was demonstrated by means of 2D and 3D seismic and borehole data, which show partial inversion of Lower and Middle Jurassic extensional structures of the Chubut and Cañadón Asfalto basins, during the earliest stages of breakup. A comparison with surrounding areas in Patagonia, where similar Jurassic intraplate compression was described, allowed the discrimination of three discrete pulses of subtle compression (C1: ∼188-185 Ma; C2: ∼170-163; C3: ∼157-136? Ma). Interestingly, episodic intraplate compressional events are closely followed by high flux magmatic events linked to the westward expansion of the Karoo-Ferrar thermal anomaly, which impacted on the lithosphere of southwest Gondwana in Lower Jurassic. In addition, we determined the approximate direction of the main compressive strain (σ1) compatible with other Jurassic intraplate belts of South America. These observations led us to propose a linkage between a thermo mechanically weakened continental crust due to LIPs activity, changes in plate motions and ridge-push forces generated by the opening of the Weddell Sea, in order to explain intraplate shortening, interrupted while Karoo LIPs magmatic invigoration took place.

  4. Cumulative beam break-up study of the spallation neutron source superconducting linac

    CERN Document Server

    Jeon, D; Krafft, G A; Yunn, B; Sundelin, R; Delayen, J; Kim, S; Doleans, M

    2002-01-01

    Beam instabilities due to High Order Modes (HOMs) are a concern to superconducting (SC) linacs such as the Spallation Neutron Source (SNS) linac. The effects of pulsed mode operation on transverse and longitudinal beam breakup instability are studied for H sup - beam in a consistent manner for the first time. Numerical simulation indicates that cumulative transverse beam breakup instabilities are not a concern in the SNS SC linac, primarily due to the heavy mass of H sup - beam and the HOM frequency spread resulting from manufacturing tolerances. As little as +-0.1 MHz HOM frequency spread stabilizes all the instabilities from both transverse HOMs, and also acts to stabilize the longitudinal HOMs. Such an assumed frequency spread of +-0.1 MHz HOM is small, and hence conservative compared with measured values of sigma=0.00109(f sub H sub O sub M -f sub 0)/f sub 0 obtained from Cornell and the Jefferson Lab Free Electron Laser cavities. However, a few cavities may hit resonance lines and generate a high heat lo...

  5. The breakup of the Southern Hemisphere spring polar ozone and temperature minimums from 1979 to 1987

    Science.gov (United States)

    Newman, Paul A.; Schoeberl, Mark R.

    1988-01-01

    The purpose of this study is to quantify the observations of the polar vortex breakup. The data used in this study consist of Total Ozone Mapping Spectrometer (TOMS) data, and National Meteorological Center (NMC) analyses. The final warming is diagnosed using the difference between zonal means at 80 degrees and 50 degrees S for temperature, ozone, and layer mean temperature. The polar vortex breakup can also be diagnosed by the onset of weak zonal mean zonal winds (i.e., u, overbar denotes a zonal average) at 60 degrees S. Computations of the polar vortex breakdown date using NMC meteorological data and TOMS total ozone data indicate that the breakdown is occurring later in the spring in the lowest portion of the stratosphere. At altitudes above 100 mb, the large interannual variance of the breakdown date renders any trend determination of the breakdown date difficult. Individual plots of TOMS total ozone indicate that the total ozone minimum remains intact for a longer period of time than is observed in earlier years.

  6. Rifting and magmatism associated with the South America and Africa break-up

    Energy Technology Data Exchange (ETDEWEB)

    Thomaz Filho, Antonio; Cesero, Pedro de [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Faculdade de Geologia; Mizusaki, Ana Maria Pimentel [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Geociencias; Milani, Edison Jose [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2000-03-01

    Based on about 380 K/Ar dating of basic and alkaline magmatic rocks from Brazilian sedimentary basins and the argentinean Atlantic margin it is possible to interpret the evolution of the rifting that caused the South America and Africa break-up. This process started in the Triassic and took place northwestward of the Foz do Amazonas basin, on the equatorial Brazilian continental margin, and reached the San Julian and North Malvinas basins, in the southern portion of South America. From this latter up to the Espirito Santo Basin, rifting took place between the Jurassic and Neocomian whereas transcurrence caused by clockwise rotation of South America on the equatorial margin generated the Potiguar Basin. The available information suggests that the final break-up of Africa and South America occurred along the eastern Brazilian margin, between the Cumuruxatiba/Mucuri and Pernambuco basins, during the Cenomanian/Turonian. The resistance offered by the Sao Luis/West African and Sao Francisco/Congo cratons promoted the huge magnetic manifestations which occur in the Brazilian paleozoic intracratonic basins (Acre, Solimoes, Amazonas, Paranaiba and Parana basins) as well as in the interior Tacutu Rift. Hot spots turned out during the drift phase, as registered by the Mecejana (CE)/Rocas Atoll/Fernando de Noronha Archipelago Alignment and Pocos de Caldas/Cabo Frio Alkaline Rocks Alignment that persists up to Vitoria/Trindade Chain. (author)

  7. Breakup, instabilities, and dynamics of high-speed droplet under transcritical conditions

    Directory of Open Access Journals (Sweden)

    Yanfei Gao

    2015-06-01

    Full Text Available A droplet breakup model is developed for a single droplet introduced into transcritical and strong convective environments. The numerical model takes into account variable thermophysical properties, gas solubility in the liquid phase, and vapor–liquid interfacial thermodynamics. The influences of ambient conditions on droplet breakup characteristics are investigated. The results indicate that (1 the drag acceleration decreases slowly at first and then increases drastically with the initial droplet temperature increasing, but always increases at a constant rate with ambient pressure; (2 the pressure and the drop temperature have similar effects on the Kelvin–Helmholtz and Rayleigh–Taylor wave growth at high pressures (reduced pressure higher than 1.2 and high temperatures (reduced temperature higher than 0.7, but the impact of pressure on the wave growth is relatively stronger than that of droplet temperature at relatively low pressures (reduced pressure lower than 0.8 and low temperatures (reduced temperature lower than 0.63; (3 the temperature significantly affects the surface instability growth at high drop temperatures (reduced temperature higher than 0.7, but has no effect on the instability growth at low temperatures (reduced temperature lower than 0.63.

  8. Explosive Ice Multiplication Induced by multiplicative-Noise fluctuation of Mechanical Break-up in Ice-Ice Collisions

    Science.gov (United States)

    Yano, Jun-Ichi; Phillips, Vaughan

    2017-04-01

    The number of ice fragments generated by break-up of large graupel in collisions with small graupel fluctuates randomly due to fluctuations in relative sizes and densities of colliding graupel particles and the stochastic nature of fracture propagation. This paper investigates an impact of the stochasticity of break-up on ice multiplication. When both the rate of generation of primary ice and the initial number concentration of ice-crystals are low, the system most likely loses all the initial ice and graupel due to a lack of sustaining sources. Even randomness does not change this mean evolution of the system in its phase-space. However, a fluctuation of ice break-up number gives a small but finite chance that substantial ice crystal fragments are generated by break-up of large graupel. That, in turn, generates more large graupel. This multiplicative process due to fluctuations potentially leads to a small but finite chance of explosive growth of ice number. A rigorous stochastic analysis demonstrates this point quantitatively. The randomness considered here belongs to a particular category called "multiplicative" noise, because the noise amplitude is proportional to a given physical state. In order to contrast the multiplicative-noise nature of ice break-up with a standard "additive" noise process, fluctuation of the primary ice generation rate is also considered as an example of the latter. These processes are examined by taking the Fokker-Planck equation that explicitly describes evolution of the probability distribution with time. As an important conclusion, stability in the phase-space of the cloud-microphysical system of break-up in ice-ice collisions is substantially altered by the multiplicative noise.

  9. Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

    Directory of Open Access Journals (Sweden)

    Byongjun Hwang

    2017-07-01

    Full Text Available Breakup of the near-continuous winter sea ice into discrete summer ice floes is an important transition that dictates the evolution and fate of the marginal ice zone (MIZ of the Arctic Ocean. During the winter of 2014, more than 50 autonomous drifting buoys were deployed in four separate clusters on the sea ice in the Beaufort Sea, as part of the Office of Naval Research MIZ program. These systems measured the ocean-ice-atmosphere properties at their location whilst the sea ice parameters in the surrounding area of these buoy clusters were continuously monitored by satellite TerraSAR-X Synthetic Aperture Radar. This approach provided a unique Lagrangian view of the winter-to-summer transition of sea ice breakup and floe size distribution at each cluster between March and August. The results show the critical timings of a temporary breakup of winter sea ice coinciding with strong wind events and b spring breakup (during surface melt, melt ponding and drainage leading to distinctive summer ice floes. Importantly our results suggest that summer sea ice floe distribution is potentially affected by the state of winter sea ice, including the composition and fracturing (caused by deformation events of winter sea ice, and that substantial mid-summer breakup of sea ice floes is likely linked to the timing of thermodynamic melt of sea ice in the area. As the rate of deformation and thermodynamic melt of sea ice has been increasing in the MIZ in the Beaufort Sea, our results suggest that these elevated factors would promote faster and more enhanced breakup of sea ice, leading to a higher melt rate of sea ice and thus a more rapid advance of the summer MIZ.

  10. Influence of margin segmentation upon the break-up of the Hatton Bank rifted margin, NE Atlantic

    Science.gov (United States)

    Elliott, Gavin M.; Parson, Lindsay M.

    2008-10-01

    The Hatton Bank margin, flanking the Iceland Basin, is an example of a volcanic rifted margin and has been studied to examine the along margin tectono-magmatic variability. Integration of 5660 km of new seismic reflection profiles with > 60,000 km 2 of new multibeam bathymetry has allowed the margin to be divided into three segments, each of which are flanked by oceanic crust. The southernmost segment is characterised by a series of inner and outer seaward dipping reflector (SDR) packages, which are separated by an "Outer High" feature. The outer SDRs are truncated by Endymion Spur, a chain of steep sided, volcanic cones connected by narrow septa or necks. The central segment has no Inner SDR package and is characterised by the presence of a continental block, the Hatton Bank Block (HBB). The northern segment is adjacent to Lousy Bank, with a wider region of SDRs recognised than to the south, and characterised by many volcanic cones. The variations in the distribution of the SDRs along the margin, the presence of the HBB and Endymion Spur all suggest that the break-up process was not a uniform smooth process along-strike. Structural segmentation controlled the variations along the margin with break-up initiated in the south, producing the SDR packages. The HBB prompted the focus of break-up to relocate outboard of the block. The northern segment was closest to the Iceland "hot-spot", and regular seafloor spreading did not become established until Chron 21. Shortly after break-up, the eruption of Endymion Spur occurred and may have been triggered by the passage of a pulse of hot asthenospheric material along the margin. The margin segmentation pattern we describe controlled the location of the enhanced volcanism along the Endymion Spur to the southern sector. In addition the segmentation has influenced the break-up style (presence or absence of SDR) and also the location and nature of post break-up volcanism.

  11. Reaction Automata

    OpenAIRE

    Okubo, Fumiya; Kobayashi, Satoshi; YOKOMORI, Takashi

    2011-01-01

    Reaction systems are a formal model that has been introduced to investigate the interactive behaviors of biochemical reactions. Based on the formal framework of reaction systems, we propose new computing models called reaction automata that feature (string) language acceptors with multiset manipulation as a computing mechanism, and show that reaction automata are computationally Turing universal. Further, some subclasses of reaction automata with space complexity are investigated and their la...

  12. Developing the yearning in situations of loss scale: convergent and discriminant validity for bereavement, romantic breakup, and homesickness.

    Science.gov (United States)

    O'Connor, Mary-Frances; Sussman, Tamara J

    2014-01-01

    Yearning is common in situations involving loss, and a hallmark of complicated grief. To study yearning empirically, the present study develops the Yearning in Situations of Loss scale (YSL), which measures yearning bereavement, romantic breakup, or homesickness. In Study 1, we identified shared characteristics across situations of loss, tested an initial version and removed items with the lowest item-scale reliability. In Study 2, the 21-item YSL was compared to scales of anxiety, depression, and loneliness, and existing scales, relevant to each loss situation. The YSL showed discriminant and convergent validity that applies to bereavement, romantic breakup, and homesickness.

  13. A phase of transient subsidence, sediment bypass and deposition of regressive-transgressive cycles during the breakup of Iberia and Newfoundland

    Science.gov (United States)

    Alves, Tiago M.; Abreu Cunha, Tiago

    2018-02-01

    Seismic, outcrop and well data from West Iberia and Newfoundland are used to investigate sediment stacking patterns during continental breakup as a function of tectonic subsidence. In West Iberia, two breakup sequences are revealed on seismic data by marked strata offlap oceanwards from the present-day continental shelf. This character is similar to Newfoundland, where correlative strata comprise Lower Cretaceous-Cenomanian coarse-grained siliciclastics accumulated around local sediment-source areas. The interpreted data reveal that the two breakup sequences: 1) materialise sediment bypass onto continental-slope depocentres that experienced important tectonic subsidence during continental breakup, but without showing typical syn-rift growth packages; 2) generate specific forced-regressive stratigraphic intervals that relate to uplift and exhumation of the proximal margin. Subsidence and sediment stacking patterns in both West Iberia and Newfoundland reflect similar continental breakup processes as they evolved from the upper lithosphere- to their mantle-breakup stages. On both margins, coarse-grained siliciclastic units on the proximal margin give rise to thick shaley successions in deep-water basins. This work also confirms that in a setting dominated by a significant sediment influx, yet lacking the burial rates of continental slope basins in Newfoundland, West Iberia comprised accommodation-driven basins during continental breakup, not necessarily sediment starved. As a corollary of our analysis, we classify breakup sequences around the world based on the characteristic lithologies of their regressive-transgressive depositional cycles.

  14. Reconstruction of the pre-breakup crustal thickness in Australia/Antarctica

    Science.gov (United States)

    Goncharov, A.

    2003-04-01

    Some 140 million years ago, Australia and Antarctica were parts of a single continent Gondwana. Before it broke into parts there was a process of extensive crustal extension. Thinning of the crust during this process was accompanied by deposition of vast amounts of sedimentary rocks along Australia’s Southern Margin, where the total sediment thickness locally (e.g., Ceduna Sub-basin) reaches 15 km. These sedimentary rocks may have been involved in oil and gas formation. Knowledge of the pre-breakup crustal thickness in Australia/Antarctica is important because it provides additional constraints for plate tectonic reconstructions of the two continents and ultimately leads to a more accurate assessment of the petroleum potential of Australia’s Southern Margin. Most reliable estimates of crustal thickness come from refraction seismic measurements which define the depth to the Moho boundary, where seismic velocity increases to 8 km/s or more. Such measurements were used in this research for Australia. Unlike Australia, Antarctica has poor coverage of seismic measurements of crustal thickness. For Antarctica, seismic measurements were supplemented by values predicted by the regression between seismically defined crustal thickness and upwardly continued gravity. Upward continuation emphasizes the effects of variations in crustal thickness in the total gravity signal. After compilation and computation of crustal thickness was completed, data points located on Australian continent were reconstructed to their pre-breakup position. The most up-to-date finite rotation parameters defining the movement of Australia relative to Antarctica were used in this process. To ensure that pre-breakup extension and thinning of the crust (during the 140 to 95 Ma time interval) were accounted for, points with crustal thickness values less than 30 km on both Australian and Antarctic margins were excluded from subsequent gridding. Crust thinner than 30 km was taken to have been affected

  15. Breakup of jet and drops during premixing phase of fuel coolant interactions

    Energy Technology Data Exchange (ETDEWEB)

    Haraldsson, Haraldur Oskar

    2000-05-01

    During the course of a hypothetical severe accident in a light water reactor, molten liquid may be introduced into a volatile coolant, which, under certain conditions, results in explosive interactions. Such fuel-coolant interactions (FCI) are characterised by an initial pre-mixing phase during which the molten liquid, metallic or oxidic in nature, undergoes a breakup (fragmentation) process which significantly increase the area available for melt-coolant contact, and thus energy transfer. Although substantial progress in the understanding of phenomenology of the FCI events has been achieved in recent years, there remain uncertainties in describing the primary and secondary breakup processes. The focus of this work is on the melt jet and drop breakup during the premixing phase of FCI. The objectives are to gain insight into the premixing phase of the FCI phenomena, to determine what fraction of the melt fragments and determine the size distribution. The approach is to perform experiments with various simulant materials, at different scales, different conditions and with variation of controlling parameters affecting jet and drop breakup processes. The analysis approach is to investigate processes at different level of detail and complexity to understand the physics, to rationalise experimental results and to develop and validate models. In the first chapter a brief introduction and review of the status of the FCI phenomena is performed. A review of previous and current experimental projects is performed. The status of the experimental projects and major findings are outlined. The first part of the second chapter deals with experimental investigation of jet breakup. Two series of experiments were performed with low and high temperature jets. The low temperature experiments employed cerrobend-70 as jet liquid. A systematic investigation of thermal hydraulic conditions and melt physical properties on the jet fragmentation and particle debris characteristics was

  16. Different modes of continental break-up triggered by a sole mantle plume: a 2D and 3D numerical study

    Science.gov (United States)

    Beniest, Anouk; Koptev, Alexander; Leroy, Sylvie; Burov, Evgueni

    2017-04-01

    We used 2D and 3D numerical models to investigate the impact of a single mantle plume on continental rifting and breakup processes. We varied the thermo-rheological structure of the continental lithosphere, its geometry and the initial plume position. Based on the results of our 2D experiments, three continental break-up modes can be distinguished: A) 'central' continental break-up, the break-up center is located directly above the original mantle anomaly position, B) 'shifted' break-up, the break-up center is 50 to 200 km displaced from the initial plume location and C) 'distant' break-up, due to convection and/or slab-subduction/delamination, the break-up center is considerably shifted (300 to 800 km) from the primary plume position. Our 3D model, with a laterally homogeneous initial setup also results in continental break-up with the axis of continental break-up hundreds of kilometers shifted from the original plume location. The model results show that the classical, 'central' view of mantle plume induced continental break-up is not the only mode of break-up. When considering a diversity of break-up styles, it is possible to explain a variety of observed geophysical and geological features. For example, the mantle material glued to the base of the lithosphere at shallower depths corresponds geometrically and location-wise to high-velocity/high-density bodies observed on seismic data below the thinned continental lithosphere and the transition zone of the South Atlantic domain. During migration, products of partial melting of the mantle material can move vertically to (shallow) lower crustal levels. They might resemble high density bodies observed at lower crustal levels inside continental crust with similar geometries observed with gravity modelling. Also, topographic variation form in the very early stages of rifting on the first impingement of upwelled plume material. These variations remain visible, as the final position of the spreading center is shifted

  17. A Model of the Bubble Break-up in a Turbulent Flow; Modelizacion de la rotura de una Burbuja en un Flujo Turbulento

    Energy Technology Data Exchange (ETDEWEB)

    Bayod, R.; Rodriguez Rodriguez, J.; Martinez Bazan, C.

    2005-07-01

    In this report, a simplified model of the break-up of an air bubble in a turbulent water flow is proposed and analyzed numerically. According to Hinze's theory, and our experimental observations, the external flow field is assumed asymmetric and irrotational for away from the bubble. furthermore the turbulent flow-field is modelled by an asymmetric hyperbolic flow-field and the evolution of the air-water interface is calculated by the levels-set method for a wide range of Reynolds and Weber numbers. Therefore, the break-up times are obtained for super-critical weber numbers and different Reynolds numbers. Therefore, the break-up times are obtained for super-critical Weber and Reynolds numbers allows the comparison of the numeric with our experimental results. Other possible break-up mechanisms for subcritical Weber number, i. e. the break-up by resonance, are also considered. (Author) 20 refs.

  18. A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

    Science.gov (United States)

    Donnadieu, Y.; GoddéRis, Y.; Pierrehumbert, R.; Dromart, G.; Fluteau, F.; Jacob, R.

    2006-11-01

    Large fluctuations in continental configuration occur throughout the Mesozoic. While it has long been recognized that paleogeography may potentially influence atmospheric CO2 via the continental silicate weathering feedback, no numerical simulations have been done, because of the lack of a spatially resolved climate-carbon model. GEOCLIM, a coupled numerical model of the climate and global biogeochemical cycles, is used to investigate the consequences of the Pangea breakup. The climate module of the GEOCLIM model is the FOAM atmospheric general circulation model, allowing the calculation of the consumption of atmospheric CO2 through continental silicate weathering with a spatial resolution of 7.5°long × 4.5°lat. Seven time slices have been simulated. We show that the breakup of the Pangea supercontinent triggers an increase in continental runoff, resulting in enhanced atmospheric CO2 consumption through silicate weathering. As a result, atmospheric CO2 falls from values above 3000 ppmv during the Triassic down to rather low levels during the Cretaceous (around 400 ppmv), resulting in a decrease in global mean annual continental temperatures from about 20°C to 10°C. Silicate weathering feedback and paleogeography both act to force the Earth system toward a dry and hot world reaching its optimum over the last 260 Myr during the Middle-Late Triassic. In the super continent case, given the persistent aridity, the model generates high CO2 values to produce very warm continental temperatures. Conversely, in the fragmented case, the runoff becomes the most important contributor to the silicate weathering rate, hence producing a CO2 drawdown and a fall in continental temperatures. Finally, another unexpected outcome is the pronounced fluctuation in carbonate accumulation simulated by the model in response to the Pangea breakup. These fluctuations are driven by changes in continental carbonate weathering flux. Accounting for the fluctuations in area available for

  19. Nonelastic nuclear reactions induced by light ions with the BRIEFF code

    CERN Document Server

    Duarte, H

    2010-01-01

    The intranuclear cascade (INC) code BRIC has been extended to compute nonelastic reactions induced by light ions on target nuclei. In our approach the nucleons of the incident light ion move freely inside the mean potential of the ion in its center-of-mass frame while the center-of-mass of the ion obeys to equations of motion dependant on the mean nuclear+Coulomb potential of the target nucleus. After transformation of the positions and momenta of the nucleons of the ion into the target nucleus frame, the collision term between the nucleons of the target and of the ion is computed taking into account the partial or total breakup of the ion. For reactions induced by low binding energy systems like deuteron, the Coulomb breakup of the ion at the surface of the target nucleus is an important feature. Preliminary results of nucleon production in light ion induced reactions are presented and discussed.

  20. Modelling of the Bubble Size Distribution in an Aerated Stirred Tank: Theoretical and Numerical Comparison of Different Breakup Models

    Directory of Open Access Journals (Sweden)

    Kálal Zbyněk

    2014-09-01

    Full Text Available The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996 typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b, Lehr et al. (2002 and Alopaeus et al. (2002 were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.

  1. Does the association between broken partnership and first time myocardial infarction vary with time after break-up?

    DEFF Research Database (Denmark)

    Kriegbaum, Margit; Christensen, Ulla; Andersen, Per Kragh

    2013-01-01

    Marriage is associated with lower risk of coronary heart disease, but it is unknown if the association depends on time since break-up with a partner. In this study we included both married and unmarried couples to study if the association between broken partnership (BP) and first time incident...

  2. Cretaceous origin of giant rhinoceros beetles (Dynastini; Coleoptera) and correlation of their evolution with the Pangean breakup.

    Science.gov (United States)

    Jin, Haofei; Yonezawa, Takahiro; Zhong, Yang; Kishino, Hirohisa; Hasegawa, Masami

    2017-03-17

    The giant rhinoceros beetles (Dynastini, Scarabaeidae, Coleoptera) are distributed in tropical and temperate regions in Asia, America and Africa. Recent molecular phylogenetic studies have revealed that the giant rhinoceros beetles can be divided into three clades representing Asia, America and Africa. Although a correlation between their evolution and the continental drift during the Pangean breakup was suggested, there is no accurate divergence time estimation among the three clades based on molecular data. Moreover, there is a long chronological gap between the timing of the Pangean breakup (Cretaceous: 110-148 Ma) and the emergence of the oldest fossil record (Oligocene: 33 Ma). In this study, we estimated their divergence times based on molecular data, using several combinations of fossil calibration sets, and obtained robust estimates. The inter-continental divergence events among the clades were estimated to have occurred about 99 Ma (Asian clade and others) and 78 Ma (American clade and African clade), both of which are after the Pangean breakup. These estimates suggest their inter-continental divergences occurred by overseas sweepstakes dispersal, rather than by vicariances of the population caused by the Pangean breakup.

  3. Comparison of Schirmer's test and tear film breakup time test to detect tear film abnormalities in patients with pterygium.

    Science.gov (United States)

    Rahman, Atiya; Yahya, Kamran; Fasih, Uzma; Waqar-ul-Huda; Shaikh, Arshad

    2012-11-01

    To compare tear film breakup time test with Schirmer's test in patients with pterygium. The case-control study, involving 86 patients with unilateral primary pterygium aged between 30 and 70 years, was conducted at the Department of Ophthalmology, Karachi Medical and Dental College, Abbasi Shaheed Hospital, from May 2009 to December 2010. The eye with pterygium was taken as the case, and was compared with the other eye without pterygium which was taken as the control in these patients. All patients underwent routine ophthalmic examination. Tear film tests such as Schirmer's test and tear film breakup time test were performed on all these eyes. Results of tear function test between the eyes with pterygium (cases) and the eye without pterygium (control) were compared. SPSS 17 was used for statistical analysis. Chi square test was used for comparing the results of the cases and the controls. Of the 86 patients, 63 (73.3%) were men, while 23 (26.7%) were women. The median age was 41 years. There were 62 (72.1%) patients with pterygium in the right eye, while 24 (27.9%) had it in the left. Among the involved eyes, decreased tear breakup time (10 seconds. On the other hand, 8 (9.3 %) eyes with pterygium had Schirmer's test positive and 78 (90.7 %) eyes had it negative. Tear film breakup time test has better diagnostic value compared to Schirmer's test in detecting tear film abnormality in patients with pterygium.

  4. Study of three-nucleon force effects in (p)over-right-arrow + d break-up with BINA

    NARCIS (Netherlands)

    Mardanpour, H.; Amir -Ahmadi, H.R.; Biegun, A.; Eslami-Kalantari, M.; Kalantar-Nayestanaki, N.; Kis, M.; Kistryn, St.; Kozela, A.; Kuboki, H.; Maeda, Y.; Mahjour-Shafiei, M.; Messchendorp, J. G.; Miki, K.; Noji, S.; Ramazani, A.; Sakai, H.; Sasano, M.; Sekiguchi, K.; Stephan, E.; Sworst, R.; Takahashi, Y.; Yako, K.; Mardanpur, H.; Eslamikalantari, M.; Benard, R.

    2007-01-01

    Extensive studies of three-nucleon force (3NF) effects in elastic proton-deuteron scattering have been performed at KVI and elsewhere in the past. In the present work, we explored 3NF effects in the break-up scattering process by performing high precision measurement of vector analyzing powers and

  5. Nd isotope constraints on ocean circulation, paleoclimate, and continental drainage during the Jurassic breakup of Pangea

    DEFF Research Database (Denmark)

    Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.

    2015-01-01

    The breakup of Pangea and onset of growth of the Pacific plate led to several paleoenvironmental feedbacks, which radically affected paleoclimate and ocean chemistry during the Jurassic. Overall, this period was characterized by intense volcanic degassing from large igneous provinces and circum...... changes in continental drainage and surface oceanic circulation for the whole Jurassic period. For this purpose, we present 53 new neodymium isotope values (εNd(t)) measured on well-dated fossil fish teeth, ichthyosaur bones, phosphatized nodules, phosphatized ooids, and clastic sediments from Europe......, western Russia, and North America. Combined with an extensive compilation of published εNd(t) data, our results show that the continental sources of Nd were very heterogeneous across the world. Volcanic inputs from a Jurassic equivalent of the modern Pacific Ring of Fire contributed to radiogenic ε...

  6. Short break-up time type dry eye has potential ocular surface abnormalities.

    Science.gov (United States)

    Ichihashi, Yoshiyuki; Ide, Takeshi; Kaido, Minako; Ishida, Reiko; Hatou, Shin; Tsubota, Kazuo

    2015-01-01

    To describe a case series in which corneal fluorescein staining (CFS) development occurred in short break-up time (s-BUT) dry eyes after a short period during prolonged opening of the eye. The study was designed as a clinical case series. Ocular surface evaluations were performed on 13 individuals with s-BUT dry eye. Tear function examinations included Schirmer's test and BUT evaluation. In all 13 cases, the BUT was short, but the tear quantity was not so bad. In all cases, CFS developed following a single eye opening, and the staining was observed at sites that showed as dark spots. In several cases, the CFS disappeared later. In this study, we demonstrated that CFS could develop following a single eye opening. Based on our findings, CFS is a dynamic phenomenon rather than a stable indicator of ocular surface abnormalities. Moreover, s-BUT dry eye has the potential to show ocular surface abnormalities.

  7. The role of three-dimensional shapes in the break-up of charged drops

    Science.gov (United States)

    Natarajan, R.; Brown, R. A.

    1987-01-01

    The nonlinear dynamics of nonaxisymmetric inviscid charged conducting drops near the Rayleigh charge limit (R = 4) is investigated analytically. It is shown that only axisymmetric spheroid drops bifurcate from the sphere family when the charge is increased, that oblate spheroids at R greater than 4 are unstable to nonaxisymmetric disturbances governing drop breakup, and that prolate spheroids at R less than 4 are unstable only to axisymmetric disturbances tending to increase the length of the drop along its symmetry axis. The effects of external electric fields and rigid-body rotation are also analyzed, and the solutions for the amplitude equations at R just less than 4 (equivalent to the dynamical equations of the Henon-Heiles Hamiltonian) are explored.

  8. High-Voltage Breakdown Penalties for the Beam-Breakup Instability

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-22

    The strength of the dangerous beam breakup (BBU) instability in linear induction accelerators (LIAs) is determined by the transverse coupling impedance Z of the induction cell cavity. For accelerating gap width w less than the beam pipe radius b, the transverse impedance is theoretically proportional to w/b, favoring narrow gaps to suppress BBU. On the other hand, cells with narrow gaps cannot support high accelerating gradients, because of electrical breakdown and shorting of the gap. Thus, there is an engineering trade-off between BBU growth and accelerating gradient, which must be considered for next generation LIAs now being designed. In this article this tradeoff is explored, using a simple pillbox cavity as an illustrative example. For this model, widening the gap to reduce the probability of breakdown increases BBU growth, unless higher magnetic focusing fields are used to further suppress the instability.

  9. When is a break-up of Gazprom good for Russia?

    Energy Technology Data Exchange (ETDEWEB)

    Tsygankova, Marina [Statistics Norway, Research Department (Norway)

    2010-07-15

    In the late 1990s, several proposals for a structural reform that would bring competition and market prices to the Russian gas industry were intensely debated. Splitting up Russian gas monopolist Gazprom into several producing companies was a considered option. In this paper, I examine theoretically and numerically how a split-up of Gazprom would affect Russian national welfare. Results show that under the current gas market structures in Europe and Russia, the split-up of Gazprom's monopoly might not be beneficial for Russia. However, analysis in the paper indicates that the market shares that Gazprom has in both Russian domestic and European gas markets are important in determining whether Gazprom's dominance is supported under the national welfare criteria. When Gazprom has small market share in Europe and large market share in Russia, a break-up of Gazprom might plausibly result in increase of Russian national welfare. (author)

  10. Memory effects, transient growth, and wave breakup in a model of paced atrium

    Science.gov (United States)

    Garzón, Alejandro; Grigoriev, Roman O.

    2017-09-01

    The mechanisms underlying cardiac fibrillation have been investigated for over a century, but we are still finding surprising results that change our view of this phenomenon. The present study focuses on the transition from normal rhythm to spiral wave chaos associated with a gradual increase in the pacing rate. While some of our findings are consistent with existing experimental, numerical, and theoretical studies of this problem, one result appears to contradict the accepted picture. Specifically we show that, in a two-dimensional model of paced homogeneous atrial tissue, transition from discordant alternans to conduction block, wave breakup, reentry, and spiral wave chaos is associated with the transient growth of finite amplitude disturbances rather than a conventional instability. It is mathematically very similar to subcritical, or bypass, transition from laminar fluid flow to turbulence, which allows many of the tools developed in the context of fluid turbulence to be used for improving our understanding of cardiac arrhythmias.

  11. Capillary break-up, gelation and extensional rheology of hydrophobically modified cellulose ethers

    Science.gov (United States)

    Sharma, Vivek; Haward, Simon; Pessinet, Olivia; Soderlund, Asa; Threlfall-Holmes, Phil; McKinley, Gareth

    2012-02-01

    Cellulose derivatives containing associating hydrophobic groups along their hydrophilic polysaccharide backbone are used extensively in the formulations for inks, water-borne paints, food, nasal sprays, cosmetics, insecticides, fertilizers and bio-assays to control the rheology and processing behavior of multi-component dispersions. These complex dispersions are processed and used over a broad range of shear and extensional rates. The presence of hydrophobic stickers influences the linear and nonlinear rheology of cellulose ether solutions. In this talk, we systematically contrast the difference in the shear and extensional rheology of a cellulose ether: ethy-hydroxyethyl-cellulose (EHEC) and its hydrophobically-modified analog (HMEHEC) using microfluidic shear rheometry at deformation rates up to 10^6 inverse seconds, cross-slot flow extensional rheometry and capillary break-up during jetting as a rheometric technique. Additionally, we provide a constitutive model based on fractional calculus to describe the physical gelation in HMEHEC solutions.

  12. A Fragment-Cloud Model for Breakup of Asteroids with Varied Internal Structures

    Science.gov (United States)

    Wheeler, Lorien; Mathias, Donovan; Stokan, Ed; Brown, Peter

    2016-01-01

    As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, we have developed an analytic asteroid fragmentation model to assess the atmospheric energy deposition of asteroids with a range of structures and compositions. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, the size-strength scaling used to increase the robustness of smaller fragments, and other parameters. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, can be given an outer regolith later, or can be defined as a coherent or fractured monolith. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

  13. Break-up of oil-in-water emulsions by electrochemical techniques.

    Science.gov (United States)

    Cañizares, Pablo; Martínez, Fabiola; Lobato, Justo; Rodrigo, Manuel Andrés

    2007-06-25

    Electrochemically-assisted technologies can be successfully applied to the treatment of oil-in-water (O/W) emulsions. In this work, it is studied the influence of the main parameters (electrical charge passed, pH, electrolyte, oil content and operation mode) in the efficiency of these processes, when aluminium electrodes are used. The pH was found to be the most significant parameter, and good removal efficiencies were only obtained for pHs in the range 5-9. The electrical charge passed was observed to be directly related to the aluminium supplied to the waste. For a given oil concentration it is required that a minimum electrical charge is passed to break-up the emulsion. Further increases in the electrical charge lead to increase in the COD removal. The influence of the oil concentration is related to that of the electrical charge passed: for a given dose of aluminium, the higher the oil content the lower the COD-removal efficiency. Likewise, to produce the break-up of the emulsion it is required a minimum dose of aluminium (electrical charge passed), lower doses do not attain the rupture of the emulsion. The type of electrolyte and its concentration were also found to influence the process efficiency. Better efficiencies were obtained in the treatment of chloride-containing wastes and for low concentration of electrolyte. The destabilization of the O/W emulsion was found to be favoured in the discontinuous operation mode. Bridging flocculation is a primary destabilization mechanism that can explain the experimental results obtained in this work.

  14. Efficacy of punctum plug treatment in short break-up time dry eye.

    Science.gov (United States)

    Kaido, Minako; Ishida, Reiko; Dogru, Murat; Tamaoki, Tomoko; Tsubota, Kazuo

    2008-08-01

    To evaluate the efficacy of punctum plug insertion on tear and dynamic visual function in dry eye patients with short break-up time (s-BUT) of the tears. A prospective comparative case series design was used. Twenty-seven eyes of 27 dry eye patients with a s-BUT seen at Keio University School of Medicine, Department of Ophthalmology, were studied. Functional visual acuity (FVA) measurements, tear function examinations and ocular surface evaluations including Schirmer test, tear break-up time, fluorescein and Rose Bengal vital staining scores were performed before and 1 month after insertion of punctum plugs (PP) in dry eye patients with s-BUT. Degree of satisfaction with the PP treatment was also graded. Nineteen out of 27 eyes (70.4%) showed a satisfactory outcome with the PP treatment because of decreased subjective dry eye symptoms. On the other hand, six out of eight eyes with an unsatisfactory outcome had epiphora. The visual maintenance ratio value was observed to significantly increase from 0.87 +/- 0.09 to 0.91 +/- 0.07 in eyes with no epiphora, whereas the visual maintenance ratio value significantly decreased from 0.98 +/- 0.10 to 0.86 +/- 0.13 in the group of eyes with epiphora after PP treatment. (p < 0.05) Likewise, FVA significantly improved after PP insertion in the group with no epiphora and decreased in eyes with epiphora. Visual acuity in the conventional Landolt visual testing remained significantly unchanged in both group of eyes with or without epiphora. FVA was useful in assessing and quantifying vision related symptomatology in s-BUT type of dry eye treated with PP occlusion.

  15. Breakup dynamics and dripping-to-jetting transition in a Newtonian/shear-thinning multiphase microsystem.

    Science.gov (United States)

    Ren, Yong; Liu, Zhou; Shum, Ho Cheung

    2015-01-07

    The breakup dynamics in non-Newtonian multiphase microsystems is associated with a variety of industrial applications such as food production and biomedical engineering. In this study, we numerically and experimentally characterize the dripping-to-jetting transition under various flow conditions in a Newtonian/shear-thinning multiphase microsystem. Our work can help to predict the formation of undesirable satellite droplets, which is one of the challenges in dispensing non-Newtonian fluids. We also demonstrate the variations in breakup dynamics between shear-thinning and Newtonian fluids under the same flow conditions. For shear-thinning fluids, the droplet size increases when the capillary number is smaller than a critical value, while it decreases when the capillary number is beyond the critical value. The variations highlight the importance of rheological effects in flows with a non-Newtonian fluid. The viscosity of shear-thinning fluids significantly affects the control over the droplet size, therefore necessitating the manipulation of the shear rate through adjusting the flow rate and the dimensions of the nozzle. Consequently, the droplet size can be tuned in a controlled manner. Our findings can guide the design of novel microdevices for generating droplets of shear-thinning fluids with a predetermined droplet size. This enhances the ability to fabricate functional particles using an emulsion-templated approach. Moreover, elastic effects are also investigated experimentally using a model shear-thinning fluid that also exhibits elastic behaviors: droplets are increasingly deformed with increasing elasticity of the continuous phase. The overall understanding in the model multiphase microsystem will facilitate the use of a droplet-based approach for non-Newtonian multiphase applications ranging from energy to biomedical sciences.

  16. Extension and stress during continental breakup: Seismic anisotropy of the crust in Northern Afar

    Science.gov (United States)

    Illsley-Kemp, Finnigan; Savage, Martha K.; Keir, Derek; Hirschberg, Hamish P.; Bull, Jonathan M.; Gernon, Thomas M.; Hammond, James O. S.; Kendall, J.-Michael; Ayele, Atalay; Goitom, Berhe

    2017-11-01

    Studies that attempt to simulate continental rifting and subsequent breakup require detailed knowledge of crustal stresses, however observational constraints from continental rifts are lacking. In addition, a knowledge of the stress field around active volcanoes can be used to detect sub-surface changes to the volcanic system. Here we use shear wave splitting to measure the seismic anisotropy of the crust in Northern Afar, a region of active, magma-rich continental breakup. We combine shear wave splitting tomography with modelling of gravitational and magmatic induced stresses to propose a model for crustal stress and strain across the rift. Results show that at the Ethiopian Plateau, seismic anisotropy is consistently oriented N-S. Seismic anisotropy within the rift is generally oriented NNW-SSE, with the exception of regions north and south of the Danakil Depression where seismic anisotropy is rift-perpendicular. These results suggest that the crust at the rift axis is characterized by rift-aligned structures and melt inclusions, consistent with a focusing of tectonic extension at the rift axis. In contrast, we show that at regions within the rift where extension rate is minimal the seismic anisotropy is best explained by the gravitationally induced stress field originating from variations in crustal thickness. Seismic anisotropy away from the rift is controlled by a combination of inherited crustal structures and gravitationally induced extension whereas at the Dabbahu region we show that the stress field changes orientation in response to magmatic intrusions. Our proposed model provides a benchmark of crustal stress in Northern Afar which will aid the monitoring of volcanic hazard. In addition we show that gravitational forces play a key role in measurements of seismic anisotropy, and must be considered in future studies. We demonstrate that during the final stages of continental rifting the stress field at the rift axis is primarily controlled by tectonic

  17. Constraining lithosphere deformation modes during continental breakup for the Iberia-Newfoundland conjugate rifted margins

    Science.gov (United States)

    Jeanniot, Ludovic; Kusznir, Nick; Mohn, Geoffroy; Manatschal, Gianreto; Cowie, Leanne

    2016-06-01

    A kinematic model of lithosphere and asthenosphere deformation has been used to investigate lithosphere stretching and thinning modes during continental rifting leading to breakup and seafloor spreading. The model has been applied to two conjugate profiles across the Iberia-Newfoundland rifted margins and quantitatively calibrated using observed present-day water loaded subsidence and crustal thickness, together with observed mantle exhumation, subsidence and melting generation histories. The kinematic model uses an evolving prescribed flow-field to deform the lithosphere and asthenosphere leading to lithospheric breakup from which continental crustal thinning, lithosphere thermal evolution, decompression melt initiation and subsidence are predicted. We explore the sensitivity of model predictions to extension rate history, deformation migration and buoyancy induced upwelling. The best fit calibrated models of lithosphere deformation evolution for the Iberia-Newfoundland conjugate margins require; (1) an initial broad region of lithosphere deformation with passive upwelling, (2) lateral migration of deformation, (3) an increase in extension rate with time, (4) focussing of the deformation and (5) buoyancy induced upwelling. The model prediction of exhumed mantle at the Iberia-Newfoundland margins, as observed, requires a critical threshold of melting to be exceeded before melt extraction. The preferred calibrated models predict faster extension rates and earlier continental crustal separation and mantle exhumation for the Iberia Abyssal Plain-Flemish Pass conjugate margin profile than for the Galicia Bank-Flemish Cap profile to the north. The predicted N-S differences in the deformation evolution give insights into the 3D evolution of Iberia-Newfoundland margin crustal separation.

  18. Mapping the Traces of the Assembly and Multistage Breakup of Gondwanaland in the Lithosphere of Madagascar

    Science.gov (United States)

    Rindraharisaona, E. J.; Tilmann, F. J.; Yuan, X.; Rumpker, G.; Heit, B.; Rambolamanana, G.; Priestley, K. F.

    2014-12-01

    Madagascar is an ideal place to study the multistage assembly and break up of Gondwanaland, the supercontinent whose breakup also gave rise to most of present day continental regions. At the end of the Proterozoic the assembly of Gondwanaland has placed the Malagasy basement between the Antarctic, Dharwar, Arabo-Nubian and Nubian-Tanzanian cratons. The continental collision processes accompanying the assembly left their mark on the Malagasy basement, currently exposed in the Eastern two thirds of the island, in the form of metamorphic and mineral belts as well as massive ductile shear zones. During the Jurassic Madagascar, India and Seychelles were breaking up from African. Long after the breakaway of India and the Seychelles from Madagascar (Cretaceous time), volcanic activation has occurred in several locations of Madagascar mostly in the central and northern part (Neogene period). The surface traces of assembly and breakup processes have been studied extensively using geological methods in Madagascar but the imprint on the deep structure has so far not been studied in much detail. Between 2012 and 2014, 25 broadband stations were operated in the Southern Madagascar extending from East coast (Mananjary) to West coast (Toliary). The array crosses the Bongolava-Ranontsara shear zone, which is one of the major shear zones in Madagascar. In addition, between 2013 and 2014, 25 short period stations were deployed in the southeastern part of Madagascar. We will present preliminarily results of the lithosphere structure in the southern part of Madagascar based on surface wave dispersion analysis from both earthquakes and ambient noise combine with receiver function analysis. We will focus mostly on the contrast between the lithosphere structure in the eastern (Precambrian rocks) and the western (Sedimentary basins) parts of Madagascar.

  19. Post-breakup Basin Evolution along the South-Atlantic Margins in Brazil and Angola/Namibia

    Science.gov (United States)

    Kukla, P. A.; Strozyk, F.; Back, S.

    2013-12-01

    The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment

  20. Drug Reactions

    Science.gov (United States)

    ... or diabetes. But medicines can also cause unwanted reactions. One problem is interactions, which may occur between ... more serious. Drug allergies are another type of reaction. They can be mild or life-threatening. Skin ...

  1. Noninvasive Keratograph assessment of tear film break-up time and location in patients with age-related cataracts and dry eye syndrome.

    Science.gov (United States)

    Jiang, Yongxiang; Ye, Hongfei; Xu, Jianjiang; Lu, Yi

    2014-04-01

    To investigate tear-film break-up time and spatial distribution via noninvasive Keratograph 4 in patients with cataracts and dry eye syndrome (DES). Noninvasive first break-up time (NIKf-BUT) and average break-up time (NIKav-BUT) were evaluated via Keratograph 4 in patients with age-related cataracts and DES. The location and size of tear break regions were recorded and the distribution of first break-up areas was summarized. Patients also underwent conventional break-up time assessments (TBUT test and Schirmer's test). A total of 43 left and 43 right eyes were examined. There was no significant difference between TBUT and NIKav-BUT. NIKf-BUT was significantly shorter than TBUT. Both NIKf-BUT and NIKav-BUT correlated positively with TBUT. In both the left and right eye, the most common first break-up areas were the peripheral domain of the inferior precorneal surface and the central domain of the superior portion. The Keratograph 4 appears to provide an effective noninvasive method for assessing tear film, enabling effective preoperative evaluation of tear film break-up regularity, informing the location of the incision and reducing the probability of postoperative DES.

  2. Causes and consequences of continental breakup in the South Atlantic: lessons learned from the SAMPLE program

    Science.gov (United States)

    Trumbull, Robert B.

    2014-05-01

    Since 2009 the SAMPLE program (www.spp-sample.de) provides a platform for research into the causes and effects of continental breakup and the evolution of passive margins. SAMPLE encompasses 28 projects from 13 German institutions and many international partnerships. The 6-year program will run through 2015. At the core of the program are observational studies that are interlinked by modelling projects examining the interplay of deep mantle dynamics, lithospheric stress fields, pre-rift fabric and melt-weaking on localizing rifting. Geophysics teams collect and integrate existing data from wide-angle seismic profiles, reprocessed multichannel seismics, as well as gravity, magnetics and heat-flow studies to construct self-consistent lithospheric-scale 3-D models along the conjugate margins. Key interests are variations in margin architecture, distribution of magmatic features and the evolution of sedimentary basins (subsidence and thermal histories). An exciting new contribution of SAMPLE geophysics is a linked set of seismic, seismologic and magnetotelluric experiments along the Walvis Ridge, including onshore NW Namibia and the Tristan da Cunha hotspot. In the deep mantle, we examine evidence from global seismic tomography for dramatic low seismic-velocity regions near the core-mantle boundary beneath southern Africa and their implications for dynamics in the deep Earth and the thermo-chemical nature of plumes. Petrologic studies focus on near-primary mantle melts represented by Mg-rich mafic dikes. Projects address the origin of magmas and crust-mantle interaction, and the environmental impact of mega-scale volcanism during breakup. Thermobarometry results from the African margin reveal a N-to-S decrease in mantle potential temperatures from 1520°C (N) to 1380° (S), which supports a thermal plume origin for excessive melt production in the north. Thermochronology data from both conjugate margins reveal complex and puzzling patterns in the denudation history

  3. High-speed monodisperse droplet generation by ultrasonically controlled micro-jet breakup

    Science.gov (United States)

    Frommhold, Philipp Erhard; Lippert, Alexander; Holsteyns, Frank Ludwig; Mettin, Robert

    2014-04-01

    A liquid jet that is ejected from a nozzle into air will disintegrate into drops via the well-known Plateau-Rayleigh instability within a certain range of Ohnesorge and Reynolds numbers. With the focus on the micrometer scale, we investigate the control of this process by superimposing a suitable ultrasonic signal, which causes the jet to break up into a very precise train of monodisperse droplets. The jet leaves a pressurized container of liquid via a small orifice of about 20 μm diameter. The break-up process and the emerging droplets are recorded via high-speed imaging. An extended parameter study of exit speed and ultrasonic frequency is carried out for deionized water to evaluate the jet's state and the subsequent generation of monodisperse droplets. Maximum exit velocities obtained reach almost 120 m s-1, and frequencies have been applied up to 1.8 MHz. Functionality of the method is confirmed for five additional liquids for moderate jet velocities 38 m s-1. For the uncontrolled jet disintegration, the drop size spectra revealed broad distributions and downstream drop growth by collision, while the acoustic control generated monodisperse droplets with a standard deviation less than 0.5 %. By adjustment of the acoustic excitation frequency, drop diameters could be tuned continuously from about 30 to 50 μm for all exit speeds. Good agreement to former experiments and theoretical approaches is found for the relation of overpressure and jet exit speed, and for the observed stability regions of monodisperse droplet generation in the parameter plane of jet speed and acoustic excitation frequency. Fitting of two free parameters of the general theory to the liquids and nozzles used is found to yield an even higher precision. Furthermore, the high-velocity instability limit of regular jet breakup described by von Ohnesorge has been superseded by more than a factor of two without entering the wind-induced instability regime, and monodisperse droplet generation was

  4. Simulations of insonated contrast agents: Saturation and transient break-up

    Science.gov (United States)

    Tsigklifis, Kostas; Pelekasis, Nikos A.

    2013-03-01

    Under insonation contrast agents are known to perform nonlinear pulsations and deform statically, in the form of buckling, or dynamically via parametric mode excitation, and often exhibit jetting and break-up like bubbles without coating. Boundary element simulations are performed in the context of axisymmetry in order to establish the nonlinear evolution of these patterns. The viscoelastic stresses that develop on the coating form the dominant force balance tangentially to the shell-liquid interface, whereas the dynamic overpressure across the shell balances viscoelastic stresses in the normal direction. Strain softening and strain hardening behavior is studied in the presence of shape instabilities for various initial conditions. Simulations recover the pattern of static buckling, subharmonic/harmonic excitation, and dynamic buckling predicted by linear stability. Preferential mode excitation during compression is obtained supercritically for strain softening phospholipid shells while the shell regains its sphericity at expansion. It is a result of energy transfer between the emerging unstable modes and the radial mode, eventually leading to saturated oscillations of shape modes accompanied by asymmetric radial pulsations in favor of compression. Strain softening shells are more prone to sustain saturated pulsations due to the mechanical behavior of the shell. As the sound amplitude increases and before the onset of dynamic buckling, both types of shells exhibit transient break-up via unbalanced growth of a number of unstable shape modes. The effect of pre-stress in lowering the amplitude threshold for shape mode excitation is captured numerically and compared against the predictions of linear stability analysis. The amplitude interval for which sustained shape oscillations are obtained is extended, in the presence of pre-stress, by switching from a strain softening constitutive law to a strain hardening one once the shell curvature increases beyond a certain

  5. Breakup of Pangaea and plate kinematics of the central Atlantic and Atlas regions

    Science.gov (United States)

    Schettino, Antonio; Turco, Eugenio

    2009-08-01

    A new central Pangaea fit (type A) is proposed for the late Ladinian (230 Ma), together with a plate motions model for the subsequent phases of rifting, continental breakup and initial spreading in the central Atlantic. This model is based on: (1) a reinterpretation of the process of formation of the East Coast Magnetic Anomaly along the eastern margin of North America and the corresponding magnetic anomalies at the conjugate margins of northwest Africa and the Moroccan Meseta; (2) an analysis of major rifting events in the central Atlantic, Atlas and central Mediterranean and (3) a crustal balancing of the stretched margins of North America, Moroccan Meseta and northwest Africa. The process of fragmentation of central Pangaea can be described by three major phases spanning the time interval from the late Ladinian (230 Ma) to the Tithonian (147.7 Ma). During the first phase, from the late Ladinian (230 Ma) to the latest Rhaetian (200 Ma), rifting proceeded along the eastern margin of North America, the northwest African margin and the High, Saharan and Tunisian Atlas, determining the formation of a separate Moroccan microplate at the interface between Gondwana and Laurasia. During the second phase, from the latest Rhaetian (200 Ma) to the late Pliensbachian (185 Ma), oceanic crust started forming between the East Coast and Blake Spur magnetic anomalies, whereas the Morrocan Meseta simply continued to rift away from North America. During this time interval, the Atlas rift reached its maximum extent. Finally, the third phase, encompassing the time interval from the late Pliensbachian (185 Ma) to chron M21 (147.7 Ma), was triggered by the northward jump of the main plate boundary connecting the central Atlantic with the Tethys area. Therefore, as soon as rifting in the Atlas zone ceased, plate motion started along complex fault systems between Morocco and Iberia, whereas a rift/drift transition occurred in the northern segment of the central Atlantic, between Morocco

  6. Reaction mechanisms in collisions induced by $^{8}$B beam close to the barrier

    CERN Multimedia

    The aim of the proposed experiment is to investigate the reaction dynamics of proton-halo induced collisions at energies around the Coulomb barrier where coupling to continuum effects are expected to be important. We propose to measure the $^{8}$B + $^{64}$Zn elastic scattering angular distribution together with the measurement, for the first time, of p - $^{7}$Be coincidences coming from transfer and/or break-up of $^{8}$B. The latter will allow a better understanding of the relative contribution of elastic $\\textit{vs}$ non-elastic break-up in reactions induced by extremely weakly-bound nuclei. We believe that with the availability of the post accelerated $^{8}$B beam at REX-ISOLDE we will be able to collect for the first time high quality data for the study of such an important topic.

  7. Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up.

    Science.gov (United States)

    Garstecki, Piotr; Fuerstman, Michael J; Stone, Howard A; Whitesides, George M

    2006-03-01

    This article describes the process of formation of droplets and bubbles in microfluidic T-junction geometries. At low capillary numbers break-up is not dominated by shear stresses: experimental results support the assertion that the dominant contribution to the dynamics of break-up arises from the pressure drop across the emerging droplet or bubble. This pressure drop results from the high resistance to flow of the continuous (carrier) fluid in the thin films that separate the droplet from the walls of the microchannel when the droplet fills almost the entire cross-section of the channel. A simple scaling relation, based on this assertion, predicts the size of droplets and bubbles produced in the T-junctions over a range of rates of flow of the two immiscible phases, the viscosity of the continuous phase, the interfacial tension, and the geometrical dimensions of the device.

  8. Analysis of parameters for the automatic computation of the tear film break-up time test based on CCLRU standards.

    Science.gov (United States)

    Ramos, L; Barreira, N; Mosquera, A; Penedo, M G; Yebra-Pimentel, E; García-Resúa, C

    2014-03-01

    Dry eye syndrome is affecting a remarkable percentage of population. The prevalence is 10-15% of normal population, and 18-30% of contact lenses users. The break-up time (BUT) is a clinical test used for the diagnosis of this disease. In this work, we perform an analysis of parameters for a global and a local automatic computation of the BUT measure, based on criteria of specificity and sensitivity. We have tested our methodology on a dataset composed of 18 videos annotated by 4 different experts. The local analysis preserves the results of the global approach providing useful additional information about the break-up tear zone. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  9. Study of beta-delayed 3-body and 5-body breakup channels observed in the decay of $^{11}$Li

    CERN Document Server

    Madurga, M; Angélique, J C; Bao, L; Bergmann, U; Butua, A; Cederkäll, J; Diget, C Aa; Fraile, L M; Fynbo, H O U; Jeppesen, H B; Jonson, B; Maréchal, F; Marqués, F M; Nilsson, T; Nyman, G; Perrot, F; Riisager, K; Tengblad, O; Tengborn, E; Turrión, M; Wilhelmsen, K

    2008-01-01

    The beta-delayed charged particle emission from ^11Li has been studied with emphasis on the three-body n+alpha+^6He and five-body 2alpha+3n channels from the 10.59 and 18.15 MeV states in ^11Be. Monte Carlo simulations using an R-matrix formalism lead to the conclusion that the ^AHe resonance states play a significant role in the break-up of these states. The results exclude an earlier assumption of a phase-space description of the break-up process of the 18.15 MeV state. Evidence for extra sequential decay paths is found for both states.

  10. Interaction forces between red cells agglutinated by antibody. IV. Time and force dependence of break-up.

    Science.gov (United States)

    Tees, D. F.; Coenen, O.; Goldsmith, H. L.

    1993-01-01

    We report on an extension of a previously described method to measure the hydrodynamic force to separate doublets of fixed, sphered and swollen red cells cross-linked by antibody (S. P. Tha, J. Shuster, and H. L. Goldsmith. 1986. Biophys. J. 50:1117-1126). With a traveling microtube apparatus, doublets are tracked and videotaped in a slowly accelerating Poiseuille flow in 150-microns-diameter tubes, and the hydrodynamic normal force at break-up, Fn, is computed from the measured doublet velocity and radial position. Previous results showed a large range of Fn, the mean of which increased with [antiserum], and an absence of clustering at discrete values of Fn. Since it was assumed that the cells separate the instant a critical force to break all crossbridges was reached, lack of clustering could have been due to the use of a polyclonal antiserum. We therefore studied the effect of monoclonal IgM or IgA antibody on the distribution of Fn. The results showed that the data are as scattered as ever, with Fn varying from 2 to 200 pN, and exhibit no evidence of clustering. However, the scatter in Fn could be due to the stochastic nature of intercellular bonds (E. Evans, D. Berk, and A. Leung. 1991a. Biophys. J. 59:838-848). We therefore studied the force dependence of the time to break-up under constant shear stress (Fn from 30 to 200 pN), both in Poiseuille and Couette flow, the latter by using a counter-rotating cone and plate rheoscope. When 280 doublets were rapidly accelerated in the traveling microtube and then allowed to coast in steady flow for up to 180 s, 91% survived into the constant force region; 16% of these broke up after time intervals, tP, of 2-30s. Of 340 doublets immediately exposed to constant shear in the rheoscope, 37% broke after time intervals, tc, from break-up decreased significantly with increasing force, while the fraction of doublets broken up increased. At a given Fn, the fraction of break-ups decreased with increasing [IgM], suggesting that

  11. Density functional theory study of CeDx with application to ejecta break-up in reactive gases

    Science.gov (United States)

    Bjorgaard, Josiah; Sheppard, Daniel

    2017-06-01

    When ejecta are produced in a reactive gas, the diffusion of the reacting gas into the ejecta particles may have an important effect on break-up. This can influence the rate of break-up, particle size, and composition. In this study, density functional theory calculations were performed to explore the properties of CeDx in support of experiments of Ce ejected into Dgas. Under these conditions, the diffusion of D into Ce ejecta is of fundamental importance to the ejecta physics. We perform quantum molecular dynamics simulations to derive fundamental quantities including temperature dependent diffusion coefficients, x dependent heat capacity, and reflectivity. Our results are interpreted in terms of relative phase composition of ejecta and discussed in application to experiments.

  12. Effects of viscoelasticity on droplet dynamics and break-up in microfluidic T-Junctions: a lattice Boltzmann study.

    Science.gov (United States)

    Gupta, Anupam; Sbragaglia, Mauro

    2016-01-01

    The effects of viscoelasticity on the dynamics and break-up of fluid threads in microfluidic T-junctions are investigated using numerical simulations of dilute polymer solutions at changing the Capillary number (Ca), i.e. at changing the balance between the viscous forces and the surface tension at the interface, up to Ca ≈ 3×10(-2). A Navier-Stokes (NS) description of the solvent based on the lattice Boltzmann models (LBM) is here coupled to constitutive equations for finite extensible non-linear elastic dumbbells with the closure proposed by Peterlin (FENE-P model). We present the results of three-dimensional simulations in a range of Ca which is broad enough to characterize all the three characteristic mechanisms of break-up in the confined T-junction, i.e. squeezing, dripping and jetting regimes. The various model parameters of the FENE-P constitutive equations, including the polymer relaxation time τP and the finite extensibility parameter L2, are changed to provide quantitative details on how the dynamics and break-up properties are affected by viscoelasticity. We will analyze cases with Droplet Viscoelasticity (DV), where viscoelastic properties are confined in the dispersed (d) phase, as well as cases with Matrix Viscoelasticity (MV), where viscoelastic properties are confined in the continuous (c) phase. Moderate flow-rate ratios Q ≈ O(1) of the two phases are considered in the present study. Overall, we find that the effects are more pronounced in the case with MV, as the flow driving the break-up process upstream of the emerging thread can be sensibly perturbed by the polymer stresses.

  13. Denudation of SW Iberia during Pangea's break-up: geochemical and detrital zircon geochronology characterization of Triassic basins

    OpenAIRE

    Pereira, M. francisco; Ribeiro, Carlos; Vilallonga, Filipa; Chichorro, Martim; Drost, Kerstin

    2010-01-01

    This provenance study is mainly based on new whole-rock geochemistry data but also involves detrital zircon geochronology. More specifically, this study investigates the Early Mesozoic denudation of a Late Paleozoic mountain range and the coeval development of basins during Pangea break-up in SW Iberia. The relations with past dynamic Earth events in Western Europe also include the amalgamation of Pangea and the development of the Carboniferous basins. U-Pb LA-ICP-MS geochronology on ...

  14. Modeling corium jet breakup in water pool and application to ex-vessel fuel–coolant interaction analyses

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Kwang-Hyun, E-mail: khbang@hhu.ac.kr; Kumar, Rohit; Kim, Hyoung-Tak

    2014-09-15

    Highlights: • Kelvin–Helmholtz Instability on melt–steam–water interfaces was solved numerically. • Corium jet breakup model was developed for FCI codes based on the KHI solutions. • Ex-vessel steam explosions in reactor cavity were calculated using TRACER-II code. - Abstract: In light water reactor core melt accidents, the molten fuel can be brought into contact with coolant water in the course of the melt relocation in-vessel and ex-vessel as well as in an accident mitigation action of water addition. For the last several decades, the potential risk of energetic molten fuel coolant interactions (FCIs, steam explosions) has drawn substantial attention in the safety analysis of reactor severe accidents. In this paper, an improved melt jet breakup model is presented and analyses of an energetic fuel–coolant interaction in a PWR cavity (1) partially filled (4 m deep) and (2) completely filled (7 m deep) with water are presented. The TRACER-II code was used in the analyses. For jet breakup model, the full dispersion equation of Kelvin–Helmholtz instability for the melt jet–vapor film–water was solved numerically and the solutions were correlated for use in the TRACER-II code. The new jet breakup model was benchmarked using FARO L28 test data. In reactor calculations the mixing calculations showed that the average melt drop size was much smaller in 4 m deep pool with 3 m free-fall than in 7 m deep pool. The explosion calculations showed that the peak pressure at the center of mixture was ∼90 MPa in 4 m deep pool, ∼25 MPa in 7 m deep pool. It also showed that the maximum impulse at the cavity wall was found at the lower wall in both cases and it was 50 kPa s in 4 m deep pool and 150 kPa s in 7 m deep pool.

  15. Insights from 2D numerical models on two-branch continental break-up: a single mantle plume's effect on a laterally heterogeneous lithosphere

    Science.gov (United States)

    Beniest, Anouk; Koptev, Alexander; Leroy, Sylvie

    2017-04-01

    We use 2D numerical models to investigate the impact of the location of one single mantle plume on the break-up evolution of realistic rheologically stratified continental lithosphere. The lithosphere is characterized by a laterally non-homogeneous rheology: a "weak" crust for the left half of the model box and a "strong" crust for the right one. We tested different experimental settings by varying three controlling parameters: the initial location of the mantle anomaly, Moho temperature and extension velocities. The results of our experiments are two-folded. Firstly, in most of the models, break-up occurs within the central part of the model domain at the boundary between weak and strong crust. This "structurally inherited" mode of continental break-up persists even when the mantle plume has been initially seeded underneath the stronger lithosphere segment with considerable (up to 300 km) shift from the central position. When the initial plume is positioned at a significant distant from this structure (>=400 km), lithospheric rupture may also develop in the "strong" half of the lithosphere directly above the upwelled plume head ("plume-centered" mode). Secondly, when the plume anomaly is seeded between 300 km and 400 km away from the boundary between the "weak" and "strong" crust, the model cultivates a two-branch rift system when both "structurally inherited" and "plume-centered" break-up develop consecutively, under the influence of one single plume. The opening of the Labrador Sea and the North Atlantic can be a natural example of a two-branch system due to one single Iceland plume. Additional experiments show that hotter crustal geotherm favors "plume-centered" mode of lithospheric rupture whereas slower far-field extension always results in "structurally inherited" break-up regardless of initial plume location. These results show that the "classical" model, where one plume anomaly produces a single break-up center situated directly overhead, is only one way

  16. Effect of family break-up and parent divorce on children.

    Science.gov (United States)

    Connell, H M

    1988-08-01

    Family break-up is a common experience in childhood today, yet reports of its effects on children vary considerably. Variables to be considered are the age, sex and previous experiences of the child as well as the observer's viewpoint (clinician compared with social scientist): the need for well founded research is obvious. Divorce is a process affecting all family members: parent disharmony and quarrels prior to the divorce appear to be more detrimental to a child's adjustment than the separation itself which may represent a relief of tension. Behaviour and emotional problems following divorce relate to litigation regarding custody and access (accusations of sexual abuse during access are not uncommon), and a diminution of living standards. Feelings of rejection, depression, anger and guilt are frequent in the immediate post-divorce period, but settle during the ensuing year. Family counselling, individual work with children (especially explanations for younger ones) and social support in the post-divorce period are suggested as a means of combating long-term, sometimes lifelong, sequelae.

  17. Fracture zones in the equatorial Atlantic and the breakup of western Pangea

    Science.gov (United States)

    Jones, E. J. W.

    1987-06-01

    The early breakup of western Pangea has been investigated by mapping the pattern of fracture zones and distribution of seismic reflectors within the sedimentary cover of the Atlantic between the Cape Verde Islands and the equator. Two distinct sets of transverse oceanic lineaments are present, separated by the Guinea Fracture Zone near lat 10°N. Lineaments to the north are associated with the formation of the central Atlantic in the Late Jurassic and Early Cretaceous; those in the south relate to the Cretaceous opening of the South Atlantic. The Guinea Fracture Zone is thus the conjugate of the Jurassic transform boundary under peninsular Florida, which linked the Atlantic with the Gulf of Mexico. The distribution of dated seismic reflectors suggests that deposition of deep-water sediments was confined to the region north of the Guinea transform until Aptian time, when the Sierra Leone Basin began to open. The latter started to widen at least 15 m.y. after the initiation of the Cape Basin off southwest Africa, an age difference that can be explained if a short-lived plate boundary developed in either Africa or South America during the Early Cretaceous. Neither the trends of the equatorial fracture zones nor the seismic stratigraphy supports the existence of a predrift gap between west Africa and Brazil.

  18. Severe symptoms of short tear break-up time dry eye are associated with accommodative microfluctuations.

    Science.gov (United States)

    Kaido, Minako; Kawashima, Motoko; Ishida, Reiko; Tsubota, Kazuo

    2017-01-01

    Validating the hypothesis that accommodative microfluctuations (AMFs) may be associated with severe symptoms in short tear break-up time (BUT) dry eye (DE). This study included 12 subjects with short BUT DE (age: 49.6±18.3 years). Diagnoses were performed based on the presence of DE symptoms, BUT ≤5 s, Schirmer score >5 mm, and negative keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA) examinations were conducted before and after DE treatment. The AMF parameters evaluated were: total high-frequency component (HFC), HFC with low accommodation for the task of staring into the distance (HFC1), HFC with high accommodation for deskwork (HFC2). A subjective questionnaire of DE symptoms was also performed. Mean BUT increased from 1.9±2.0 to 6.4±2.5 s after treatment (P0.05). Subjective DE symptoms were reduced in nine patients. Along with the improvement of BUT after treatment, DE symptoms diminished and HFC1 and functional VA improved, suggesting that tear film instability is associated with deterioration of functional VA, AMF, and DE symptoms.

  19. Effect of contact lens wear and a near task on tear film break-up.

    Science.gov (United States)

    Jansen, Meredith E; Begley, Carolyn G; Himebaugh, Nikole H; Port, Nicholas L

    2010-05-01

    To study the effect of extrinsic controls on blinking by examining blink parameters and tear stability among adapted soft contact lens (CL) wearers performing tasks that require varying amounts of visual concentration. The Demographic Questionnaire, Contact Lens Dry Eye Questionnaire, and Current Symptoms Questionnaire were completed by 15 adapted soft CL wearers (nine females). Three 55 s simultaneous measurements of tear film stability via retroillumination and blinking were obtained with a slit-lamp biomicroscope and 200 Hz video camera while subjects listened to music and played a video game with and without their habitual CLs. Interblink interval (IBI) and blink amplitude (BA) were calculated. The area of break-up (AB) was calculated for the retroillumination image before each blink. The Current Symptoms Questionnaire was completed four times throughout testing. With the game compared to music, IBI was significantly longer and BA significantly decreased without CLs (p or = 0.5579, p or = 0.6262, p or = 0.5064, p < 0.0001). During tasks requiring concentration, the IBI increased (blink rate decreased) and many blinks were incomplete without CLs. With CLs, tear film instability increased. Blinking frequency also increased, but it remained high when subjects played the game, and symptoms of ocular irritation increased. This suggests that wearing soft CLs, even when fully adapted, provides enough extrinsic ocular surface stimulation to override internal controls and affect blink parameters.

  20. Effects of diquafosol tetrasodium administration on visual function in short break-up time dry eye.

    Science.gov (United States)

    Kaido, Minako; Uchino, Miki; Kojima, Takashi; Dogru, Murat; Tsubota, Kazuo

    2013-01-01

    To investigate the effect of diquafosol tetrasodium on tear and visual function in short break-up time (sBUT) dry eye (DE). This interventional nonrandomized comparative study involved 11 eyes in 11 patients with sBUT DE (symptom-positive sBUT group) and 13 eyes in 13 volunteers with BUT values ≤5 s without DE symptoms (symptom-negative sBUT group). Tear function was assessed by measuring BUT and Schirmer values. Serial measurements were made of visual acuities (using a functional visual acuity measurement system) and higher-order aberrations (using a wavefront sensor). The parameters were compared before and 1 month after diquafosol tetrasodium instillation. Any changes in symptomatology after administration were also recorded. After diquafosol tetrasodium administration, BUT values tended to increase in the symptom-positive sBUT group (P=0.07) and significantly increased in the symptom-negative sBUT group (P0.05). Diquafosol tetrasodium administration provided relief of DE symptoms in 75% of patients in the symptom-positive sBUT group. Diquafosol tetrasodium appeared to improve tear film stability and visual function in sBUT DE.

  1. The non-invasive tear film break-up time in normal children.

    Science.gov (United States)

    Jones, Sophie M; Nischal, Ken K

    2013-09-01

    To perform an objective evaluation of the non-invasive tear break-up time (NITBUT) and lipid layer interferometry in normal children. Children with no known ocular surface disease or anterior segment abnormality were evaluated. We excluded patients with disorders affecting lid margins or tear film composition. NITBUT and lipid layer interferometry were performed using a Keeler tearscope mounted on a slit lamp. The time from eye opening to the first distortion of the grid was noted. The average of three readings was taken as the NITBUT. Thirty-six children (71 eyes) were included (mean age 7.64 years, range 2.16-15.83 years). Mean NITBUT was 21.76 ± 4.06 s (range 14.9-30.95). This is significantly higher in comparison to recent adult studies utilising the tearscope. Twenty-four children allowed tearscope lipid layer interferometry. Eighteen demonstrated grade 1 and six demonstrated grade 2. These grades are within the normal tear film range. To our knowledge, this prospective study is the first to evaluate NITBUT in normal children. The results demonstrate that NITBUT is greater in children in comparison to adults. These normative data are a useful benchmark for further research into tear film instability in children.

  2. Dynamics of double emulsion break-up in three phase glass capillary microfluidic devices.

    Science.gov (United States)

    Nabavi, Seyed Ali; Gu, Sai; Vladisavljević, Goran T; Ekanem, Ekanem E

    2015-07-15

    Pinch-off of a compound jet in 3D glass capillary microfluidic device, which combines co-flowing and countercurrent flow focusing geometries, was investigated using an incompressible three-phase axisymmetric Volume of Fluid-Continuum Surface Force (VOF-CSF) numerical model. The model showed good agreement with the experimental drop generation and was capable of predicting formation of core/shell droplets in dripping, narrowing jetting and widening jetting regimes. In dripping and widening jetting regimes, the presence of a vortex flow around the upstream end of the necking thread facilitates the jet break-up. No vortex flow was observed in narrowing jetting regime and pinch-off occurred due to higher velocity at the downstream end of the coaxial thread compared to that at the upstream end. In all regimes, the inner jet ruptured before the outer jet, preventing a leakage of the inner drop into the outer fluid. The necking region moves at the maximum speed in the narrowing jetting regime, due to the highest level of shear at the outer surface of the thread. However, in widening jetting regime, the neck travels the longest distance downstream before it breaks. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Numerical studies of spray breakup in a gasoline direct injection (GDI engine

    Directory of Open Access Journals (Sweden)

    Jafarmadar Samad

    2011-01-01

    Full Text Available The objective of this study is to investigate Spray Breakup process of sprays injected from single and two-hole nozzles for gasoline direct Injection (GDI engines by using three dimensional CFD code. Spray characteristics were examined for spray tip penetration and other characteristics including: the vapor phase concentration distribution and droplet spatial distribution, which were acquired using the computational fluid dynamics (CFD simulation. Results showed that as the hole-axis-angle (γ of the two-hole nozzle decreased, the droplet coalescence increased and vapor mass decreased. The spray with cone angle (θ0 5 deg for single hole nozzle has the longest spray tip penetration and the spray with the γ of 30 deg and spray cone angle θ0=30 deg for two hole nozzles had the shortest one. Also, when the spray cone angle (θ0 and hole-axis-angle (γ increased from 5 to 30 deg, the Sauter mean diameter (SMD decreased for both single-hole and two-hole nozzles used in this study. For a single-hole nozzle, when spray cone angle increased from 5 to 30 deg, the vaporization rate very much because of low level of coalescence. The result of model for tip penetration is good agreement with the corresponding experimental data in the literatures.

  4. Speculations on the mechanisms for the formation and breakup of supercontinents

    Directory of Open Access Journals (Sweden)

    J. Brendan Murphy

    2013-03-01

    Full Text Available The supercontinent cycle has had a profound effect on the Earth's evolution since the Late Archean but our understanding of the forces responsible for its operation remains elusive. Supercontinents appear to form by two end-member processes: extroversion, in which the oceanic lithosphere surrounding the supercontinent (exterior ocean is preferentially subducted (e.g. Pannotia, and introversion in which the oceanic lithosphere formed between dispersing fragments of the previous supercontinent (interior ocean is preferentially subducted (e.g. Pangea. Extroversion can be explained by “top–down” geodynamics, in which a supercontinent breaks up over a geoid high and amalgamates above a geoid low. Introversion, on the other hand, requires that the combined forces of slab-pull and ridge push (which operate in concert after supercontinent break-up must be overcome in order to enable the previously dispersing continents to turn inward. Introversion may begin when subduction zones are initiated along boundaries between the interior and exterior oceans and become trapped within the interior ocean. We speculate that the reversal in continental motion required for introversion may be induced by slab avalanche events that trigger the rise of superplumes from the core-mantle boundary.

  5. Numerical Simulation of Bubble Coalescence and Break-Up in Multinozzle Jet Ejector

    Directory of Open Access Journals (Sweden)

    Dhanesh Patel

    2016-01-01

    Full Text Available Designing the jet ejector optimally is a challenging task and has a great impact on industrial applications. Three different sets of nozzles (namely, 1, 3, and 5 inside the jet ejector are compared in this study by using numerical simulations. More precisely, dynamics of bubble coalescence and breakup in the multinozzle jet ejectors are studied by means of Computational Fluid Dynamics (CFD. The population balance approach is used for the gas phase such that different bubble size groups are included in CFD and the number densities of each of them are predicted in CFD simulations. Here, commercial CFD software ANSYS Fluent 14.0 is used. The realizable k-ε turbulence model is used in CFD code in three-dimensional computational domains. It is clear that Reynolds-Averaged Navier-Stokes (RANS models have their limitations, but on the other hand, turbulence modeling is not the key issue in this study and we can assume that the RANS models can predict turbulence of the carrying phase accurately enough. In order to validate our numerical predictions, results of one, three, and five nozzles are compared to laboratory experiments data for Cl2-NaOH system. Predicted gas volume fractions, bubble size distributions, and resulting number densities of the different bubble size groups as well as the interfacial area concentrations are in good agreement with experimental results.

  6. Strain distribution across magmatic margins during the breakup stage: Seismicity patterns in the Afar rift zone

    Science.gov (United States)

    Brown, C.; Ebinger, C. J.; Belachew, M.; Gregg, T.; Keir, D.; Ayele, A.; Aronovitz, A.; Campbell, E.

    2008-12-01

    Fault patterns record the strain history along passive continental margins, but geochronological constraints are, in general, too sparse to evaluate these patterns in 3D. The Afar depression in Ethiopia provides a unique setting to evaluate the time and space relations between faulting and magmatism across an incipient passive margin that formed above a mantle plume. The margin comprises a high elevation flood basalt province with thick, underplated continental crust, a narrow fault-line escarpment underlain by stretched and intruded crust, and a broad zone of highly intruded, mafic crust lying near sealevel. We analyze fault and seismicity patterns across and along the length of the Afar rift zone to determine the spatial distribution of strain during the final stages of continental breakup, and its relation to active magmatism and dike intrusions. Seismicity data include historic data and 2005-2007 data from the collaborative US-UK-Ethiopia Afar Geodynamics Project that includes the 2005-present Dabbahu rift episode. Earthquake epicenters cluster within discrete, 50 km-long magmatic segments that lack any fault linkage. Swarms also cluster along the fault-line scarp between the unstretched and highly stretched Afar rift zone; these earthquakes may signal release of stresses generated by large lateral density contrasts. We compare Coulomb static stress models with focal mechanisms and fault kinematics to discriminate between segmented magma intrusion and crank- arm models for the central Afar rift zone.

  7. Experimental Observations on the Deformation and Breakup of Water Droplets Near the Leading Edge of an Airfoil

    Science.gov (United States)

    Vargas, Mario; Feo, Alex

    2011-01-01

    This work presents the results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. An airfoil model placed at the end of the rotating arm was moved at speeds of 50 to 90 m/sec. A monosize droplet generator was employed to produce droplets that were allowed to fall from above, perpendicular to the path of the airfoil at a given location. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure from the high speed movies the horizontal and vertical displacement of the droplet against time. The velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of a given droplet from beginning of deformation to breakup and/or hitting the airfoil. Results are presented for droplets with a diameter of 490 micrometers at airfoil speeds of 50, 60, 70, 80 and 90 m/sec

  8. Stability analysis applied to the early stages of viscous drop breakup by a high-speed gas stream

    Science.gov (United States)

    Padrino, Juan C.; Longmire, Ellen K.

    2013-11-01

    The instability of a liquid drop suddenly exposed to a high-speed gas stream behind a shock wave is studied by considering the gas-liquid motion at the drop interface. The discontinuous velocity profile given by the uniform, parallel flow of an inviscid, compressible gas over a viscous liquid is considered, and drop acceleration is included. Our analysis considers compressibility effects not only in the base flow, but also in the equations of motion for the perturbations. Recently published high-resolution images of the process of drop breakup by a passing shock have provided experimental evidence supporting the idea that a critical gas dynamic pressure can be found above which drop piercing by the growth of acceleration-driven instabilities gives way to drop breakup by liquid entrainment resulting from the gas shearing action. For a set of experimental runs from the literature, results show that, for shock Mach numbers >= 2, a band of rapidly growing waves forms in the region well upstream of the drop's equator at the location where the base flow passes from subsonic to supersonic, in agreement with experimental images. Also, the maximum growth rate can be used to predict the transition of the breakup mode from Rayleigh-Taylor piercing to shear-induced entrainment. The authors acknowledge support of the NSF (DMS-0908561).

  9. Tectonomagmatic controls on Gondwana break-up models: Evidence from the Proto-Pacific Margin of Antarctica

    Science.gov (United States)

    Storey, Bryan C.; Alabaster, Tony

    1991-12-01

    Geochemical and isotopic data are presented that suggest the existence of a large, Middle Jurassic subduction-related magmatic province common to both the Antarctic Peninsula and southern South America. We argue that during the initial stages of Gondwana breakup, Pacific margin magmas were derived from an enriched lithospheric mantle source similar to that for the contemporaneous within-plate Ferrar-Tasman suite. Enriched lithospheric initial-rifting magmas were succeeded, in at least part of the Rocas Verdes basin, by transitional early drift magmas and then by entirely asthenospheric mid-ocean ridge basalt (MORB) magmas representing lithospheric rupture and seafloor spreading. We propose a plate interaction model for the initial stages of Gondwana breakup relating the broad zone of lithospheric mantle melting to a reduction in plate boundary forces. The change from Gondwanide compression to lithospheric extension in the Jurassic is linked to a change from shallow to steeply dipping subduction and to a slowing of subduction rates caused possibly by a decreasing age of the subducting plate. Ridge-trench interaction may have followed subduction of young, hot oceanic lithosphere, possibly causing a temporary cessation of subduction and a further reduction in plate boundary forces, thus facilitating breakup.

  10. MULTIPHASE DROPLET/SLUG BREAK-UP MECHANISM IN MICROFLUIDIC T-JUNCTIONS AT VARIOUS WEBER NUMBERS

    Directory of Open Access Journals (Sweden)

    Wan Leng (Dawn Leow

    2011-10-01

    Full Text Available Normal 0 false false false EN-MY X-NONE X-NONE The formation of immiscible liquid droplets, or slugs, in microchannels features the advantages of volume control and mixing enhancement over single-phase microflows. Although the applications of droplet-based microfluidics have been widely demonstrated, the fundamental physics governing droplet break-up remains an area of active research. This study defines an effective Weber (Weeff number that characterizes the interplay of interfacial tension, shear stress and channel pressure drop in driving slug formation in T-junction microchannel for a relative range of low, intermediate and high flow rates. The immiscible fluid system in this study consists of Tetradecane slug formation in Acetonitrile. The progressive deformation of slug interfaces during break-up events is observed. Experimental results indicate that, at a relatively low Weeff, clean slug break-up occurs at the intersection of the side and main channels. At intermediate Weeff, the connecting neck of the dispersed phase is stretched to a short and thin trail of laminar flow prior to breaking up a short distance downstream of the T-junction. At a relatively high Weeff, the connecting neck develops into a longer and thicker trail of laminar flow that breaks up further downstream of the main channel.

  11. An operational calculus framework to characterize droplet size populations from turbulent breakup by a small number of parameters

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, Rafael; Ganan-Calvo, Alfonso M, E-mail: amgc@us.e [Departamento de IngenierIa Aeroespacial y Mecanica de Fluidos, Universidad de Sevilla, e-41092 Sevilla (Spain)

    2010-05-07

    A systematic operational calculus framework that characterizes droplet/bubble size distributions resulting from turbulent breakup of an immiscible fluid into a carrier one is presented. The proposed formulation is derived from dynamical arguments; a finite-difference formulation of the integro-differential continuous coagulation and fragmentation equation is shown to exhibit the same structure as a discrete sequence of Mellin convolutions between the probability distribution of the evolving dispersed phase and a generic kernel. This kernel may have its physical correspondence with the probability distribution resulting from a single breakup event, e.g. a liquid ligament breakup in a ligament-mediated spray formation. The number of convolution steps in the sequence can be reduced to a single parameter. As an illustration, this procedure is applied to the exponential and the gamma distributions, obtaining as a result the Frechet distribution earlier used by Rosin and Rammler (1934 Kolloid-Zeitschrift 67 16-26), and by Nukiyama and Tanasawa (1939 Trans. Soc. Mech. Eng. Japan 5 62-7). Thus, the framework introduced in this work provides a physical foundation for the success of the Frechet distribution in accurately fitting experimentally measured droplet size distributions in sprays and emulsions.

  12. Exclusive breakup of 7Li incident on a proton target at 5.44 A MeV

    Science.gov (United States)

    Pakou, A.; Sgouros, O.; Soukeras, V.; Cappuzzello, F.; Keeley, N.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Calabrese, S.; Carbone, D.; Cavallaro, M.; Foti, A.; Marquínez-Durán, G.; Martel, I.; Mazzocco, M.; Parascandolo, C.; Pierroutsakou, D.; Rusek, K.; Strano, E.; Zagatto, V. A. B.; Zerva, K.

    2017-04-01

    An exclusive measurement of the breakup of 7Li incident on a proton target was performed at 38.1 MeV (5.44 MeV/nucleon), probing the direct part of the excitation to the continuum. The two cluster constituents of 7Li, 4He, and 3H, were recorded in coincidence in the MAGNEX spectrometer and a silicon detector respectively. Both detection systems were set at forward angles and the measurement of both kinematical solutions allowed the determination of a breakup angular distribution over a wide angular range in the center-of-mass frame. Comprehensive simulations provided the detection efficiency of the system and via the appropriate kinematics the transformation of the cross sections from the laboratory to the center-of-mass reference frame. The experimental results are analyzed and discussed together with previous elastic scattering data using the Continuum Discretized Coupled Channels (CDCC) framework and are found to be in satisfactory agreement. It was found that while the breakup cross section was dominated by the nonresonant component, the most important influence on the elastic scattering was due to coupling to the 7 /2- resonance of 7Li.

  13. Implementation of a new energy-angular distribution of particles emitted by deuteron induced nuclear reaction in transport simulations

    Science.gov (United States)

    Sauvan, Patrick; Koning, Arjan; Ogando, Francisco; Sanz, Javier

    2017-09-01

    MCUNED code is an MCNPX extension able to handle evaluated nuclear data library for light ion transport simulations. In this work the MCUNED code is improved to describe more accurately the neutron emission during deuteron induced nuclear reaction. This code update consists in introducing a new methodology to take into account the angular distribution of neutron produced by deuteron breakup reaction. To carry out this work a new formulation for the angular distribution of neutrons produced by breakup reaction has been proposed. The implementation of this new methodology requires the use of extra parameters which are provided by the nuclear code TALYS and stored in the ENDF file. This new methodology shows significant improvement in comparison with the former treatment of neutron emission kinematics, these results are in good agreement with experimental data.

  14. Magma-Assisted Continental Break-up Encroached on Previously Stretched Continental Lithosphere - the NE Greenland Composite Passive Margin

    Science.gov (United States)

    Mazur, S.; Rippington, S.; Houghton, P.

    2014-12-01

    Volcanic continental margins have a number of distinctive features that are different from those typical of magma-poor continental margins. However, in some places volcanic margins may develop parallel to older, highly extended rift systems. In such situations the resultant continental margin shows a complex structure that merges the characteristics of volcanic and non-volcanic margins. Furthermore, the evolution of this younger magma-rich margin is restricted by the pre-existing lithospheric architecture, causing it to diverge from the generally assumed formation model. We use the case of NE Greenland to demonstrate the structure of a composite margin firstly subjected to extensive extension and later overprinted by magma-assisted continental break-up. The NE Greenland continental margin is a highly extended margin, that is up to 250km wide, with crystalline crust attaining the maximum thickness near to the coast of Greenland and at the Danmarkshaven Ridge. The latter represents a major basement horst formed during an Early Cretaceous rifting event. To the east of the Danmarkshaven Ridge, crust is stretched and onlapped by the Early Cretaceous sedimentary basin. The effects of Tertiary break-up are observable in a relatively narrow zone 80 km wide that usually includes an extended edge of continental crust and an adjacent section of oceanic crust. A volcano-sedimentary succession produced during the break-up reaches the maximum thickness of c. 8000 m above a continent-ocean transition (COB). Oceanic crust overlain by mixed volcanic and sedimentary rocks is thicker than usual. No observable SDRs or igneous transitional crust are present near to the COB. Instead, a chain of high density bodies follow the COB at the base of crust. The features observed suggest relatively little extension associated with the Tertiary break-up. Instead localised mantle melting presumably led to rapid break-up with crustal dilatation promptly balanced by production of thick oceanic

  15. Inelastic collisions of heavy ions and their reaction mechanisms; Collisions inelastiques d'ions lourds et mecanismes de reaction

    Energy Technology Data Exchange (ETDEWEB)

    Scarpaci, J.A

    2004-06-01

    This work is dedicated to the study of inelastic collisions of heavy ions. Most experiments took place in Ganil facility. The 2 first chapters introduce the notion of inelastic scattering of heavy ions. The third chapter deals with target excitation, giant monopolar or dipolar or quadrupolar resonances ant the multi-phonon concept and presents relevant experimental results from the Ca{sup 40} + Ca{sup 40} nuclear reaction at 50 MeV/A. The fourth chapter is dedicated to nuclear processes involved in inelastic collisions: pick-up break-up mechanisms, the angular distribution of emitted protons and the towing mode. These notions are applied to the reaction Zr{sup 90}(Ar{sup 40}, Ar{sup 40}'). The fifth chapter presents the solving of the time dependent Schroedinger equation (TDSE) applied to the wave function of a particle plunged in a variable potential. TDSE solving is applied to the break-up of Be{sup 11}. These calculations have been validated by comparing them with experimental results from the nuclear reaction Ti{sup 48}(Be{sup 11}, Be{sup 10} + n + {gamma}) that is described in the chapter 6. The last chapter presents the advantages of inelastic scattering considered as a tool to study exotic nuclei.

  16. Experiment E89-044 of quasi-elastic diffusion 3He(e,e'p) at Jefferson Laboratory: Analyze cross sections of the two body breakup in parallel kinematics; Experience E89-044 de diffusion quasi-elastique 3he(e,e'p) au Jefferson Laboratory : analyse des sections efficaces de desintegration a deux corps en cinematique parallele

    Energy Technology Data Exchange (ETDEWEB)

    Penel-Nottaris, Emilie [Univ. Joseph Fourier Grenoble (France)

    2004-07-01

    The Jefferson Lab Hall A experiment has measured the 3He(e,e'p) reaction cross sections. The separation of the longitudinal and transverse response functions for the two-body breakup reaction in parallel kinematics allows to study the bound proton electromagnetic properties in the 3He nucleus and the involved nuclear mechanisms beyond impulse approximation. Preliminary cross sections show some disagreement with theoretical predictions for the forward angles kinematics around 0 MeV/c missing momenta, and sensitivity to final state interactions and 3He wave functions for missing momenta of 300 MeV/c.

  17. Break-up of Pangaea and Tectonic History of the Adria Microplate

    Science.gov (United States)

    Schettino, A.; Turco, E.

    2008-12-01

    A new kinematic model is proposed for the tectonic evolution of the western Tethys and the Adria microplate, constrained by the Atlantic plate kinematics and on land geologic evidences. The model defines thirteen tectonic phases, spanning the time interval from the late Ladinian (230 Ma) to the present. During the first phase, from the late Ladinian (230 Ma) to the latest Rhaetian (200 Ma), rifting proceeded along the eastern margin of North America, the northwest African margin, the High, Saharan and Tunisian Atlas, determining the formation of a separate Moroccan microplate at the interface between Gondwana and Laurasia. To the East, the break-up of Pangaea proceeded through a new phase of spreading in the central Mediterranean (Lagonegro basin) and the Tethys Ocean, while Adria remained attached to the southern Eurasian margin. During the second phase, from the latest Rhaetian (200 Ma) to the late Pliensbachian (185 Ma), oceanic crust started forming between the East Coast and Blake Spur magnetic anomalies, while the Morrocan Meseta simply continued to rift away from North America. During this time interval the Atlas rift reached its maximum extent. In the western Tethys region, cessation of spreading in the Lagonegro and Ionian Basins was accompanied by the formation of a new plate boundary which rifted Adria from Eurasia. The third phase, from the late Pliensbachian (185 Ma) to chron M21 (147.7 Ma), was triggered by the northward jump of the main plate boundary connecting the central Atlantic with the Tethys area. Therefore, as soon as rifting in the Atlas zone ceased, plate motion started along complex fault systems between Morocco and Iberia, while a rift/drift transition occurred in the northern segment of the central Atlantic, between Morocco and the conjugate margin of Nova Scotia. Sea floor spreading also started in the Mediterranean area, forming the Ligurian and Alpine Tethys oceans. The next two phases, from chron M21 (147.7 Ma) to chron M0 (120

  18. Global description of the 7Li+p reaction at 5.44 MeV/u in a continuum-discretized coupled-channels approach

    Science.gov (United States)

    Pakou, A.; Cappuzzello, F.; Keeley, N.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Calabrese, S.; Carbone, D.; Cavallaro, M.; Foti, A.; Marquínez-Durán, G.; Martel, I.; Mazzocco, M.; Parascandolo, C.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Soukeras, V.; Strano, E.; Zagatto, V. A. B.; Zerva, K.

    2017-09-01

    The complete set of open channels for the 7Li+p system, namely elastic scattering, inelastic scattering, breakup, the 7Li+p →7Be+n charge exchange reaction, and the 7Li+p →4He+4He reaction, was measured in the same experiment in inverse kinematics at an energy of 5.44 MeV/u. Data were also obtained for the charge exchange reaction at energies of 5.0 and 3.57 MeV/u. The elastic and inelastic scattering and breakup data were reported previously and are reviewed here and, together with the new data for the other two reactions, are discussed coherently within the same continuum-discretized coupled-channels model framework.

  19. Spectator invariance test in the study of the Trojan Horse Method 6,7Li fusion reactions via the Trojan Horse Method

    Directory of Open Access Journals (Sweden)

    Li C.

    2011-10-01

    Full Text Available Fusion reactions play a crucial role for several astrophysical scenarios. At the low energies typical of such environments direct measurements of reaction cross sections are very difficult, and even sometimes impossible. In such cases the use of indirect methods can give a substantial help. The Trojan Horse Method (THM is based on the quasi-free break-up of a nucleus, which can be described in terms of a cluster structure. In such applications the independence of THM results with different break-up schemes, was tested using the quasi free3 He(6Li,ααH and 3He(7Li,αα2H reactions. Results were then compared with the direct behaviours obtained from available data as well as with the cross sections extracted from previous indirect investigations of the same binary reactions using a different nuclide as a Trojan Horse nucleus.

  20. The utility of measuring tear film break-up time for prescribing contact lenses.

    Science.gov (United States)

    Mousavi, Maryam; Jesus, Danilo A; Garaszczuk, Izabela K; Szczesna-Iskander, Dorota H; Iskander, D Robert

    2018-02-01

    To evaluate the clinical value of non-invasive keratograph tear film breakup time (NIKBUT) in the assessment of pre-corneal and pre-lens tear film quality for prescribing contact lenses (CLs). Forty-six subjects aged 25.5±4.3 (mean±standard deviation) years were recruited. Visual acuity (VA), anterior eye health checks and NIKBUT were evaluated. On the following day, subjects were fitted with a daily Silicon Hydrogel (SiHy) CL in one eye and a Hydrogel (Hy) CL in the other. After four hours one material for both eyes was chosen based on a qualitative analysis which included VA, CL fitting and comfort. Information about the first and the mean NIKBUT was then contrasted against the prescription decision. Thirty-four subjects were fitted with SiHy and twelve with Hy CL. No statistically significant differences were found for both NIKBUT parameters between left and right eye at baseline (p=0.38 and p=0.50, respectively) and post four hours of CL wear (p=0.61 and p=0.06). The chosen lens did not always correspond to longer NIKBUT. In 39.1% and 34.8% of cases (i.e., 18 and 16 out of 46), there was a match between prescription decision and the first and the mean NIKBUT results, respectively. Although there is no evidence whether tear film surface quality measurement has a superior diagnostic values compared to other traditional clinical measures used in practice, NIKBUT measurements have provided additional information that could be of interest during CL fit. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  1. Modelling of Break-up and Coalescence in Bubbly Two-Phase Flows

    Directory of Open Access Journals (Sweden)

    Simon Lo

    2009-01-01

    Full Text Available Numerical simulations of gas-liquid two-phase flow with high superficial velocity in a vertical pipe were conducted with the use of the commercial software package STAR-CD 3.27. The change in bubble size due to breakup and coalescence was modelled by the Sγ model. The applicability and performance of the Sγ model in modelling of gasliquid bubbly flow were studied. The sensitivity of the Sγ model to the distribution moment γ, and the drainage mode were investigated. The numerical results were compared with the experimental data of Hibiki et al., (2001. Good agreement was achieved for axial velocities and void fraction for all tested cases. It was found in this work that the Sγ model is capable of predicting with reasonable accuracy the bubble size and its distribution even in high void fraction. Except in the near wall region, the simulated bubble size and therefore the interfacial area density fit well with the experiment measurements. It was observed that the predicted bubble size and interfacial area density obtained from both the S0 and S2 models are more or less the same, indicating that the numerical results are independent of the distribution moment γ. It was further found that, the drainage mode greatly affects the bubble size: an increase in mobility of the bubble surface enhances the coalescence and leads to an over-prediction of the bubble size in the pipe centre. The bubble size increases with the increase of the gas phase superficial velocity while the variation of the interfacial area density is smaller as it is a combined function of the bubble size and local gas hold-up.

  2. Measurement of the time course of optical quality and visual deterioration during tear break-up.

    Science.gov (United States)

    Liu, Haixia; Thibos, Larry; Begley, Carolyn G; Bradley, Arthur

    2010-06-01

    To compare changes in optical quality and visual performance that accompany tear break-up (TBU) during blink suppression. A three-channel optical system was developed that simultaneously measured refractive aberrations (Shack-Hartmann aberrometer), 20/40 letter contrast sensitivity (CS), and TBU (retroillumination, RI). Ten wearers of silicone hydrogel contact lenses were asked to keep one eye open for approximately 18 seconds, while CS, wavefront aberrations, and RI images were collected. The wavefront was reconstructed by zonal methods, and image quality was quantified with a series of metrics including RMS fit error. Novel metrics for quantifying TBU over the contact lens surface were developed by quantifying the contrast of the RI image and by using Fourier descriptors of the first Purkinje (PJ) image shape. There was a full range of TBU over the lens surface, with four subjects showing TBU across the corneal center and one subject with TBU in the inferior peripheral pupil. Among the four subjects with central corneal TBU, RMS fit error, RI contrast, and PJ Fourier descriptors showed high correlation with CS (r(2) range, 0.9187-0.9414, 0.6261-0.975, and 0.4917-0.8986, respectively). Some of the general optical-quality metrics such as blur strength, neural sharpness, and area of modulation transfer function (MTF) also showed that change correlated with CS loss. Optical metrics of tear quality and retinal image quality are associated with the decline in vision that occurs with TBU. The evidence supports the hypothesis that blurry vision symptoms reported by contact lens wearers are caused by poor quality of the retinal image due to TBU.

  3. Measurement of the Time Course of Optical Quality and Visual Deterioration during Tear Break-Up

    Science.gov (United States)

    Thibos, Larry; Begley, Carolyn G.; Bradley, Arthur

    2010-01-01

    Purpose. To compare changes in optical quality and visual performance that accompany tear break-up (TBU) during blink suppression. Methods. A three-channel optical system was developed that simultaneously measured refractive aberrations (Shack-Hartmann aberrometer), 20/40 letter contrast sensitivity (CS), and TBU (retroillumination, RI). Ten wearers of silicone hydrogel contact lenses were asked to keep one eye open for approximately 18 seconds, while CS, wavefront aberrations, and RI images were collected. The wavefront was reconstructed by zonal methods, and image quality was quantified with a series of metrics including RMS fit error. Novel metrics for quantifying TBU over the contact lens surface were developed by quantifying the contrast of the RI image and by using Fourier descriptors of the first Purkinje (PJ) image shape. Results. There was a full range of TBU over the lens surface, with four subjects showing TBU across the corneal center and one subject with TBU in the inferior peripheral pupil. Among the four subjects with central corneal TBU, RMS fit error, RI contrast, and PJ Fourier descriptors showed high correlation with CS (r2 range, 0.9187–0.9414, 0.6261–0.975, and 0.4917–0.8986, respectively). Some of the general optical-quality metrics such as blur strength, neural sharpness, and area of modulation transfer function (MTF) also showed that change correlated with CS loss. Conclusions. Optical metrics of tear quality and retinal image quality are associated with the decline in vision that occurs with TBU. The evidence supports the hypothesis that blurry vision symptoms reported by contact lens wearers are caused by poor quality of the retinal image due to TBU. PMID:20107168

  4. Ground-state configuration of neutron-rich 35Al via Coulomb breakup

    Science.gov (United States)

    Chakraborty, S.; Datta, Ushasi; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chartier, M.; Cortina-Gil, D.; De Angelis, G.; Fernandez, P. Diaz; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Johansson, H.; Jonson, B.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, M. V.; Rigollet, C.; Rossi, D.; Scheidenberger, C.; Scheit, H.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Utsuno, Y.; Wagner, A.; Wamers, F.; Weick, H.; Winfield, J. S.

    2017-09-01

    The ground-state configuration of 35Al has been studied via Coulomb dissociation (CD) using the LAND-FRS setup (GSI, Darmstadt) at a relativistic energy of ˜403 MeV/nucleon. The measured inclusive differential CD cross section for 35Al, integrated up to 5.0 MeV relative energy between the 34Al core and the neutron using a Pb target, is 78(13) mb. The exclusive measured CD cross section that populates various excited states of 34Al is 29(7) mb. The differential CD cross section of 35Al→34Al+n has been interpreted in the light of a direct breakup model, and it suggests that the possible ground-state spin and parity of 35Al could be, tentatively, 1 /2+ or 3 /2+ or 5 /2+ . The valence neutrons, in the ground state of 35Al, may occupy a combination of either l =3 ,0 or l =1 ,2 orbitals coupled with the 34Al core in the ground and isomeric state(s), respectively. This hints of a particle-hole configuration of the neutron across the magic shell gaps at N =20 ,28 which suggests narrowing the magic shell gap. If the 5 /2+ is the ground-state spin-parity of 35Al as suggested in the literature, then the major ground-state configuration of 35Al is a combination of 34Al(g.s.;4-) ⊗νp3/2 and 34Al(isomer;1+) ⊗νd3/2 states. The result from this experiment has been compared with that from a previous knockout measurement and a calculation using the SDPF-M interaction.

  5. Experiment E89-044 on the Quasielastic 3He(e,e'p) Reaction at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Penel-Nottaris, Emilie [Univ. Joseph Fourier Grenoble (France)

    2004-07-07

    The Jefferson Lab Hall A E89-044 experiment has measured the 3He(e,e'p) reaction cross-sections. The extraction of the longitudinal and transverse response functions for the two-body break-up 3He(e,e'p)d reaction in parallel kinematics allows the study of the bound proton electromagnetic properties inside the 3He nucleus and the involved nuclear mechanisms beyond plane wave approximations.

  6. Novel formulation of glycerin 1% artificial tears extends tear film break-up time compared with Systane lubricant eye drops.

    Science.gov (United States)

    Gensheimer, William G; Kleinman, David M; Gonzalez, Mithra O; Sobti, Deepak; Cooper, Eugene R; Smits, Gerard; Loxley, Andrew; Mitchnick, Mark; Aquavella, James V

    2012-10-01

    To evaluate the effectiveness of glycerin 1% formulated with the novel and proprietary ophthalmic excipient poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) (Eyeon Particle Sciences LLC) in extending tear film break-up time (TFBUT) compared with a market-leading artificial tear formulation of propylene glycol (0.3%) and polyethylene glycol (0.4%) (Systane(®) Lubricant Eye Drops; Alcon, Fort Worth, TX). This prospective single-center, single visit, randomized, double-masked exploratory trial compared the new formulation and Systane using TFBUT. Noninvasive break-up time (NIBUT) was measured in subjects with asymptomatic to mild (n=5), mild to moderate (n=5), and moderate to severe (n=6) dry eye disease using the TearscopePlus™ at pre-instillation and again at 15, 30, 60, and 120 min after instillation. Fluorescein break-up time (FBUT) was measured at 120 min after instillation. At 15 min (N=16), the new formulation extended mean NIBUT by 14.67 s (P=0.05) compared with 7.40 s (P=0.34) by Systane. The new formulation had a mean FBUT of 4.92 s longer than Systane at 120 min (P=0.12). With outliers removed (N=13), the difference between the mean NIBUT change from baseline for the new formulation and Systane at 120 min was statistically significant (P=0.03). This study demonstrates that PLL-g-PEG as a polymer excipient in artificial tears is effective in improving the performance of demulcents to significantly prolong NIBUT at 15 min, and that protective activity from this artificial tear product for 2 or more hours after eye drop instillation is possible.

  7. Down-Regulation of Love Feelings After a Romantic Break-Up: Self-Report and Electrophysiological Data.

    Science.gov (United States)

    Langeslag, Sandra J E; Sanchez, Michelle E

    2017-08-31

    Because remaining love feelings for an ex-partner are negatively associated with recovery from a romantic break-up, it may be helpful to decrease those love feelings. Love regulation is the use of behavioral or cognitive strategies to change the intensity of current feelings of romantic love. This study evaluated three regulation strategies: (1) negative reappraisal of the ex-partner, (2) reappraisal of love feelings, and (3) distraction. It was tested how these regulation strategies change love feelings for the ex-partner, valence of affect, and motivated attention for the ex-partner. Participants who were upset about a romantic break-up performed these regulation strategies before passively viewing a picture of their ex-partner, during which their electroencephalogram was recorded. Negative reappraisal decreased love feelings and made participants feel more unpleasant. Love reappraisal did not change how in love or pleasant/unpleasant participants felt. Distraction did not change love feelings but made participants feel more pleasant. This suggests that in the context of a romantic break-up, negative reappraisal is an effective love down-regulation strategy, whereas distraction is an effective positive emotion up-regulation strategy. Furthermore, all three strategies decreased motivated attention for the ex-partner, as indicated by a reduced amplitude of the late positive potential. This reduced motivated attention for the ex-partner could make it easier to deal with encounters of (reminders of) the ex-partner. Love regulation is a promising phenomenon with important everyday life and clinical implications. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  8. Constraining the role of magma before, during and after the break-up of continents using seismic reflection data

    Science.gov (United States)

    Magee, C.; Jackson, C. A. L.; Schofield, N.; Holford, S. P.

    2014-12-01

    The ability to visualize networks of igneous intrusions in 3D using seismic reflection data has revolutionized our understanding of how magma migrates and is emplaced during continental breakup. Numerous seismic-based studies have shown that: (i) sub-horizontal or saucer-shaped sill intrusions represent a major component of magmatic systems within sedimentary basins; (ii) these sills may be interconnected to form laterally extensive (>100's km2) sill-complexes; (iii) magma flow indicators can be mapped within the sills to reconstruct magma migration routes and source positions; (iv) space-making mechanisms (e.g., forced folds) can be identified, which provide constraints on intrusive style (e.g., brittle or non-brittle); and (v) cross-cutting and seismic-stratigraphic relationships between the sills and host rock can be used to constrain the age of igneous activity. We use a series of seismic data, primarily from the Rockall Basin, NE Atlantic and offshore Australia, to demonstrate how the observations described above can be synthesized to reconstruct the evolution of ancient magmatic systems located along continental volcanic rifted margins. Our results demonstrate that the architecture of such intrusive networks is significantly influenced by the pre-existing structure and lithology of the host rock. Importantly, relatively dating the intrusive and extrusive components of magmatic systems suggests igneous activity may occur more intermittently and over longer time periods than previously thought, potentially spanning entire break-up histories. Overall, seismic reflection data provide important insights into: (i) the role of magma before, during and after continental break-up; and (ii) the influence of crystallised intrusion networks on subsequent basin evolution and fluid flow processes.

  9. Turbulent dispersion of slightly buoyant oil droplets and turbulent breakup of crude oil droplets mixed with dispersants

    Science.gov (United States)

    Gopalan, Balaji

    In part I, high speed in-line digital holographic cinematography is used for studying turbulent diffusion of slightly buoyant 0.5-1.2 mm diameter diesel droplets (specific gravity of 0.85) and 50 mum diameter neutral density particles. Experiments are performed in a 50x50x70 mm3 sample volume in a controlled, nearly isotropic turbulence facility, which is characterized by 2-D PIV. An automated tracking program has been used for measuring velocity time history of more than 17000 droplets and 15000 particles. The PDF's of droplet velocity fluctuations are close to Gaussian for all turbulent intensities ( u'i ). The mean rise velocity of droplets is enhanced or suppressed, compared to quiescent rise velocity (Uq), depending on Stokes number at lower turbulence levels, but becomes unconditionally enhanced at higher turbulence levels. The horizontal droplet velocity rms exceeds the fluid velocity rms for most of the data, while the vertical ones are higher than the fluid only at the highest turbulence level. The scaled droplet horizontal diffusion coefficient is higher than the vertical one, for 1 crossing trajectories effect. The droplet diffusion coefficients scaled by the product of turbulence intensity and an integral length scale is a monotonically increasing function of u'i /Uq. Part II of this work explains the formation of micron sized droplets in turbulent flows from crude oil droplets pre-mixed with dispersants. Experimental visualization shows that this breakup starts with the formation of very long and quite stable, single or multiple micro threads that trail behind millimeter sized droplets. These threads form in regions with localized increase in concentration of surfactant, which in turn depends on the flow around the droplet. The resulting reduction of local surface tension, aided by high oil viscosity and stretching by the flow, suppresses capillary breakup and explains the stability of these threads. Due to increasing surface area and diffusion of

  10. Nd break-up process with considering 3NF at intermediate energies in a 3D approach

    Energy Technology Data Exchange (ETDEWEB)

    Radin, M., E-mail: harzchi@kntu.ac.ir; Ghasemi, H.

    2016-01-15

    In this work we have applied a three-dimensional approach to solve the three-nucleon Faddeev equation in the Jacobi momenta space. To this end, we have considered the inhomogeneous part of the Faddeev equation as an appropriate approximation for projectile intermediate energies. As an application the Bonn-B and the Tucson–Melbourne two- and three-nucleon forces have been used for calculating the differential cross section for proton–deuteron break-up process. Finally, comparing our results with the experimental data has been performed for 197 MeV and 346 MeV projectile energies.

  11. Particle aerosolisation and break-up in dry powder inhalers 1: evaluation and modelling of venturi effects for agglomerated systems.

    Science.gov (United States)

    Wong, William; Fletcher, David F; Traini, Daniela; Chan, Hak-Kim; Crapper, John; Young, Paul M

    2010-07-01

    This study utilized a combination of computational fluid dynamics (CFD) and standardized entrainment tubes to investigate the influence of turbulence on the break-up and aerosol performance of a model inhalation formulation. Agglomerates (642.8 mum mean diameter) containing 3.91 mum median diameter primary spherical mannitol particles were prepared by spheronisation. A series of entrainment tubes with different Venturi sections were constructed in silico, and the flow pattern and turbulence/impaction parameters were predicted using CFD. The entrainment models were constructed from the in silico model using three-dimensional printing. The aerosol performance of the mannitol was assessed by entraining the agglomerates into the experimental tubes at a series of flow rates and assessing the size distribution downstream of the venturi via in-line laser diffraction. A series of parameters (including Reynolds number (Re), turbulence kinetic energy, turbulence eddy frequency, turbulence length-scale, velocity and pressure drop) were calculated from the CFD simulation. The venturi diameter and volumetric flow rate were varied systematically. The particle size data of the agglomerated powders were then correlated with the CFD measurements. No correlation between turbulence and aerosol performance could be made (i.e. at a Reynolds number of 8,570, the d(0.1) was 52.5 mum +/- 19.7 mum, yet at a Reynolds number of 12,000, the d(0.1) was 429.1 mum +/- 14.8 mum). Lagrangian particle tracking indicated an increase in the number of impactions and the normal velocity component at the wall, with increased volumetric airflow and reduced venturi diameter. Chemical analysis of the mannitol deposited on the walls showed a linear relationship with respect to the theoretical number of impactions (R(2) = 0.9620). Analysis of the relationship between the CFD results and the experimental size data indicated a critical impact velocity was required to initiate agglomerate break-up

  12. Study on breakup of liquid ligaments in hypersonic cross flow using laser sheet imaging and infrared light extinction spectroscopy

    Science.gov (United States)

    Regert, T.; Horvath, I.; Buchlin, J.-M.; Masutti, D.; Chazot, O.; Vetrano, M. R.; Lapebie, C.; Le Gallic, C.

    2017-06-01

    This paper presents and discusses the results of tests of breakup phenomenon of liquid water into a hypersonic cross §ow from the surface of a 7 degree half-angle cone model at zero degree angle of incidence. The present work shows the dependence of the liquid phase characteristics on the cross-section area of the injection hole in a Mach 6 cross flow. The results are analyzed qualitatively by imaging, by Interferometric Laser Imaging for Droplet Sizing (ILIDS), and by InfraRed Light Extinction Spectroscopy (IR-LES). Conclusions are drawn concerning the droplet size distribution and the liquid §ow ¦eld characteristics.

  13. Study of the p+{sup 12}C reaction at energies up to 30 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Masahide; Yamamoto, A.; Yoshioka, S. [Kyushu Univ., Fukuoka (Japan)] [and others

    1998-03-01

    Double differential cross sections of charged-particles emitted in the p+{sup 12}C reaction were measured in the energy region from 14 to 26 MeV. The observed continuous components of emitted protons and {alpha}-particles were analyzed by assuming sequential decay of intermediate reaction products and/or simultaneous breakup process. It was found that the three body simultaneous decay, p+{alpha}+{sup 8}Be, and the sequential decay via p+{sup 12}C{sup *}{sub 3-} and {alpha}+{sup 9}B{sub g.s.} are most important in the proton-induced breakup of {sup 12}C for energies up to 30 MeV. (author)

  14. Updated evidences of the Trojan Horse particle invariance for $^2$H(d,p)$^3$H reaction

    CERN Document Server

    Pizzone, R G; Bertulani, C A; Mukhamedzhanov, A M; Blokhintsev, L; La Cognata, M; Lamia, L; Rinollo, A; Spartá, R; Tumino, A

    2012-01-01

    The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was tested using the quasi free $^2$H($^6$Li, pt)$^4$He and $^2$H($^3$He,pt)H reactions after $^6$Li and $^3$He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the Plane Wave Approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  15. Continental Break-up Above A Mantle Plume: Opening of The Southern Red Sea

    Science.gov (United States)

    Ebinger, C.; Eagles, G.; Elders, C.; Gloaguen, R.; McClay, K.; Tiberi, C.; Wolfenden, E.

    Initial rifting in the Red Sea occurred concurrent with, or soon after flood basaltic mag- matism at~31 Ma in the Ethiopia-Yemen plume province. Yet, the development of the ca. 400 km-wide extensional province of the southern Red Sea between 31 Ma and the onset of seafloor spreading at ~4 Ma has been poorly understood, in large part owing to inaccessibility in the Afar depression. The Afar depression is a diffuse extensional province marking a triple point zone between plate boundaries in the Red Sea (Arabia Nubia), the Gulf of Aden (Arabia Somalia); and the Main Ethiopian Rift (Somalia Nu- bia). Complicating this setting, the Danakil horst is a microplate lying between oceanic provinces in the southernmost Red Sea and incipient seafloor spreading in the northern Afar depression. We have integrated exploration seismic, gravity, well, and magnetic data from offshore regions with remote sensing, geological and geophysical data from Ethiopia, Eritrea, and Yemen to evaluate models for continental break-up above mantle plumes. Plate kinematic reconstructions using a pole of rotation within the error ellipse of the Chu and Gordon (1999) pole predict real features in remote sensing and gravity data; these reconstructions provide a general framework for our interpretations. Field and geochronology studies along the western margin of Afar show a southward prop- agation of rifting since about 25 Ma when extension commenced offshore Red Sea and in Yemen. We also see an eastward migration of strain from the western border fault to narrow zones of primarily basaltic magmatism since mid-Miocene time. These magmatic sequences, where not onlapped by Pliocene-Recent sedimentary strata, dip steeply seaward and define a regional eastward flexure into transitional oceanic crust, as suggested by gravity models constrained by existing seismic data. Our synthesis suggests that the southern Afar depression, assumed to be most proximal to the plume, was the site of incipient seafloor

  16. Tear Osmolarity, Break-up Time and Schirmer's Scores in Parkinson's Disease.

    Science.gov (United States)

    Söğütlü Sarı, Esin; Koç, Rabia; Yazıcı, Alper; Şahin, Gözde; Çakmak, Harun; Kocatürk, Tolga; Ermiş, Sıtkı Samet

    2015-08-01

    Dry eye is an important problem in Parkinson's disease (PD) with a potential to affect life quality. Tear osmolarity, accepted as the gold standard in dry eye diagnosis, has not been studied in this subset of patients so far. Therefore, in this study we aimed to evaluate tear osmolarity, Schirmer's test scores and tear film break-up time (TBUT) in PD patients. PD patients with a minimum follow-up of 1 year and healthy controls who admitted for refractive abnormalities were enrolled to the study. Subjects using any systemic medication with a possibility to affect tear tests were not included in the study. The presence of any ocular surface disorder, previous ocular surgery, previous dry eye diagnosis, any topical ophthalmic medication or contact lens use were other exclusion criteria. Age, gender, disease duration, and Hoehn and Yahr (H&Y) score for disease severity were noted, and blink rate (BR), Schirmer's test score, TBUT and tear osmolarity of the right eye were measured in both groups. Thirty-seven PD patients and 37 controls were enrolled to the study. The groups were age and gender matched. The mean disease duration and H&Y score were 5.70±2.64 years and 1.70±0.93, respectively. H&Y staging and disease duration were not correlated to BR, Schirmer's scores, TBUT, or tear osmolarity (p>0.05). The mean BR was 8.54±4.99 blinks/minute in PD patients and 11.97±6.36 blinks/minute in the control group. Mean Schirmer's scores, TBUT and osmolarity values were 9.08±4.46 mm, 11.38±4.05 seconds and 306.43±12.63 mOsm/L in the PD group and 17.16±9.57 mm, 12.81±3.66 seconds and 303.81±16.13 mOsm/L in the control group. The differences were significant only in BR and Schirmer's scores. BR and Schirmer's scores decreased significantly in PD patients. Although not significant, the demonstrated tear osmolarity increment might be important to document the dry eye and inflammatory process of the ocular surface in PD patients.

  17. Tear Osmolarity, Break-up Time and Schirmer’s Scores in Parkinson’s Disease

    Science.gov (United States)

    Söğütlü Sarı, Esin; Koç, Rabia; Yazıcı, Alper; Şahin, Gözde; Çakmak, Harun; Kocatürk, Tolga; Ermiş, Sıtkı Samet

    2015-01-01

    Objectives: Dry eye is an important problem in Parkinson’s disease (PD) with a potential to affect life quality. Tear osmolarity, accepted as the gold standard in dry eye diagnosis, has not been studied in this subset of patients so far. Therefore, in this study we aimed to evaluate tear osmolarity, Schirmer’s test scores and tear film break-up time (TBUT) in PD patients. Ma­te­ri­als and Met­hods: PD patients with a minimum follow-up of 1 year and healthy controls who admitted for refractive abnormalities were enrolled to the study. Subjects using any systemic medication with a possibility to affect tear tests were not included in the study. The presence of any ocular surface disorder, previous ocular surgery, previous dry eye diagnosis, any topical ophthalmic medication or contact lens use were other exclusion criteria. Age, gender, disease duration, and Hoehn and Yahr (H&Y) score for disease severity were noted, and blink rate (BR), Schirmer’s test score, TBUT and tear osmolarity of the right eye were measured in both groups. Re­sults: Thirty-seven PD patients and 37 controls were enrolled to the study. The groups were age and gender matched. The mean disease duration and H&Y score were 5.70±2.64 years and 1.70±0.93, respectively. H&Y staging and disease duration were not correlated to BR, Schirmer’s scores, TBUT, or tear osmolarity (p>0.05). The mean BR was 8.54±4.99 blinks/minute in PD patients and 11.97±6.36 blinks/minute in the control group. Mean Schirmer’s scores, TBUT and osmolarity values were 9.08±4.46 mm, 11.38±4.05 seconds and 306.43±12.63 mOsm/L in the PD group and 17.16±9.57 mm, 12.81±3.66 seconds and 303.81±16.13 mOsm/L in the control group. The differences were significant only in BR and Schirmer’s scores. Conclusion: BR and Schirmer’s scores decreased significantly in PD patients. Although not significant, the demonstrated tear osmolarity increment might be important to document the dry eye and inflammatory process of

  18. Mechanism of Supercooled Water Droplet Breakup near the Leading Edge of an Airfoil

    Science.gov (United States)

    Veras-Alba, Belen; Palacios, Jose; Vargas, Mario; Ruggeri, Charles; Bartkus, Tadas P.

    2017-01-01

    This work presents the results of an experimental study on supercooled droplet deformation and breakup near the leading edge of an airfoil. The results are compared to prior room temperature droplet deformation results to explore the effects of droplet supercooling. The experiments were conducted in the Adverse Environment Rotor Test Stand (AERTS) at The Pennsylvania State University. An airfoil model placed at the end of the rotor blades mounted onto the hub in the AERTS chamber was moved at speeds ranging between 50 and 80 m/sec. The temperature of the chamber was set at -20°C. A monotonic droplet generator was used to produce droplets that fell from above, perpendicular to the path of the airfoil. The supercooled state of the droplets was determined by measurement of the temperature of the drops at various locations below the droplet generator exit. A temperature prediction code was also used to estimate the temperature of the droplets based on vertical velocity and the distance traveled by droplets from the droplet generator to the airfoil stagnation line. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging provided droplet deformation information as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure the horizontal and vertical displacement of the droplet against time. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the ratio of the slip velocity and the initial droplet velocity must be equal. A case with equal slip velocity to initial velocity ratios was selected for room temperature and supercooled droplet conditions. The airfoil velocity was 60 m/s and the slip velocity for both sets of data was 40 m/s. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends. The similar behavior for both environmental conditions indicates that water

  19. Trajectories of Psychological Adaptation to Marital Breakup after a Long-Term Marriage.

    Science.gov (United States)

    Knöpfli, Bina; Morselli, Davide; Perrig-Chiello, Pasqualina

    2016-01-01

    Marital dissolution is known to be among the most stressful life events with long-reaching negative consequences on individuals' lives. A limitation in research to date is that most studies have focused on the impact of marital disruption on well-being outcomes in younger adults. Furthermore, although population-based studies on divorce document a broad range of negative effects, more fine-grained analyses reveal a large heterogeneity in people's adjustment, which is still not well understood. The aim was to explore trajectories of psychological adaptation to marital breakup after a long-term marriage, and to examine variables accounting for recovery or chronicity in terms of intrapersonal resources (personality, trait resilience, and personal growth), relationship variables (satisfaction with ex-relationship, length of marriage, and time since divorce), and sociodemographic variables (age, gender, and financial situation). Latent transition analysis is used to examine the course of psychological adaptation (i.e., depressive symptoms, life satisfaction, hopelessness, mourning, and subjective health) to divorce over 2 years among 5 profiles of 308 divorcees (mean age: 55.6 years; average duration of former marriage: 23.62 years). We present two larger groups of individuals, one of which adapted very well ('resilients', 29%) and the other quite well ('average copers', 49%), as well as three groups with major difficulties ('vulnerables', 6%; 'malcontents', 12%, and 'resigned', 4%). In a second step, the differences between transition patterns were explored on the basis of the distal variables (i.e., intrapersonal resources, relationship variables, and sociodemographics). Although the probability of upward changes was higher for those individuals with lower adaptation at time point 1, only a small number of individuals made an upward change from the maladapted to the well-adapted groups throughout the 2 years. The groups of copers and resilients remained stable in

  20. Tabular Iceberg Evolution and Break-up at Low Latitude: Imitating Ice Shelves

    Science.gov (United States)

    Scambos, T.; Sergienko, O.; Sargent, A.; Macayeal, D.; Fastook, J.; Long, D.

    2005-12-01

    Over the past five years, a series of large icebergs have calved from the Ronne Ice Shelf front and drifted northward, first along the Antarctic Peninsula east coast, and later across the Scotia Sea towards South Georgia Island. The bergs broke up or disintegrated within a year of reaching the island. Observations of the icebergs using MODIS, ICESat, and QuikScat have revealed details of their evolution and break-up patterns. ICESat elevation profiles of tabular iceberg margins and the Ronne Ice Shelf edge reveal shapes indicative of two types of bending forces. Icebergs and shelf fronts in sea-ice-covered areas have broad (~1000m wide), rounded, ~0.6m high `berms' and outer edges that slope down several meters toward the water. Bergs in warmer water have 2 to 5m `ramparts' with ~1500m wide edge-parallel `moats' inboard of the edge. This latter pattern was first revealed in images from International Space Station (ISS) showing edge-parallel melt ponds on one iceberg just prior to its disintegration. Model results indicate the patterns are caused by hydrostatic and lithostatic forces acting on the ice face. "Berm' profiles arise from differences between ice and water pressure along the face. `Rampart-moat' profiles result from waterline erosion, creating a submerged bench of ice that lifts the ice edge. In cold (sea-ice covered) water, icebergs evolve slowly, with infrequent calving of large blocks, usually along pre-existing fractures. In warmer water north of the ice edge, bergs show more frequent edge-parallel calvings ('edge-wasting') in which berg shape is little changed, but berg area gradually decreases. Scatterometry observations of the icebergs indicate the berg firn undergoes significant evolution during northward drift, due to melt and melt percolation. The pattern of winter backscatter change for icebergs (over time) is similar to the variations of ice shelf backscatter with melt frequency (over space, i.e. latitude). This supports the hypothesis that

  1. Tear Osmolarity, Break-up Time and Schirmer’s Scores in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Esin Söğütlü Sarı

    2015-08-01

    Full Text Available Objectives: Dry eye is an important problem in Parkinson’s disease (PD with a potential to affect life quality. Tear osmolarity, accepted as the gold standard in dry eye diagnosis, has not been studied in this subset of patients so far. Therefore, in this study we aimed to evaluate tear osmolarity, Schirmer’s test scores and tear film break-up time (TBUT in PD patients. Materials and Methods: PD patients with a minimum follow-up of 1 year and healthy controls who admitted for refractive abnormalities were enrolled to the study. Subjects using any systemic medication with a possibility to affect tear tests were not included in the study. The presence of any ocular surface disorder, previous ocular surgery, previous dry eye diagnosis, any topical ophthalmic medication or contact lens use were other exclusion criteria. Age, gender, disease duration, and Hoehn and Yahr (H&Y score for disease severity were noted, and blink rate (BR, Schirmer’s test score, TBUT and tear osmolarity of the right eye were measured in both groups. Results: Thirty-seven PD patients and 37 controls were enrolled to the study. The groups were age and gender matched. The mean disease duration and H&Y score were 5.70±2.64 years and 1.70±0.93, respectively. H&Y staging and disease duration were not correlated to BR, Schirmer’s scores, TBUT, or tear osmolarity (p>0.05. The mean BR was 8.54±4.99 blinks/minute in PD patients and 11.97±6.36 blinks/minute in the control group. Mean Schirmer’s scores, TBUT and osmolarity values were 9.08±4.46 mm, 11.38±4.05 seconds and 306.43±12.63 mOsm/L in the PD group and 17.16±9.57 mm, 12.81±3.66 seconds and 303.81±16.13 mOsm/L in the control group. The differences were significant only in BR and Schirmer’s scores. Conclusion: BR and Schirmer’s scores decreased significantly in PD patients. Although not significant, the demonstrated tear osmolarity increment might be important to document the dry eye and inflammatory

  2. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    models of regioselectivity in pericyclic reactions. In addition, local hard and soft acid base (HSAB) princi- ples have been also employed to predict the observed regioselectivity.2 In recent years, the conceptual density functional theory has been remarkably successful in explaining the reactivity and site selectivity.3 The.

  3. Effectiveness of Combined Tear Film Therapy in Patients with Evaporative Dry Eye with Short Tear Film Breakup Time.

    Science.gov (United States)

    Kim, Yung Hui; Kang, Yeon Soo; Lee, Hyo Seok; Choi, Won; You, In Cheon; Yoon, Kyung Chul

    2017-10-01

    The aim of this study was to evaluate the effectiveness of combined tear film therapy targeted to aqueous, mucin, and lipid layers in patients with refractory evaporative dry eye (EDE) with short tear film breakup time (TBUT). The patients who had EDE with short TBUT and severe symptoms refractory to artificial tears were treated with hyaluronic acid (HA) 0.15% and diquafosol tetrasodium (DQS) 3% (Group 1), HA and carbomer-based lipid-containing eyedrops (Liposic EDO Gel, LPO) (Group 2), or HA, DQS, and LPO (Group 3). Ocular Surface Disease Index (OSDI) score, visual analog scale (VAS) symptom score, TBUT, Schirmer score, and corneal and conjunctival staining scores were evaluated, and noninvasive tear film breakup time (NIBUT) and tear meniscus height were measured using Keratograph ® 5 M before and 1 and 3 months after treatment. OSDI scores, VAS scores, TBUT, and NIBUT were improved at 1 and 3 months after treatment in all groups (all P film layers was most effective in improving ocular symptoms and tear film quality.

  4. Connections Between the Spring Breakup of the Southern Hemisphere Polar Vortex, Stationary Waves, and Air-sea Roughness

    Science.gov (United States)

    Garfinkel, Chaim I.; Oman, Luke David; Barnes, Elizabeth A.; Waugh, Darryn W.; Hurwitz, Margaret H.; Molod, Andrea M.

    2013-01-01

    A robust connection between the drag on surface-layer winds and the stratospheric circulation is demonstrated in NASA's Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Specifically, an updated parameterization of roughness at the air-sea interface, in which surface roughness is increased for moderate wind speeds (4ms to 20ms), leads to a decrease in model biases in Southern Hemispheric ozone, polar cap temperature, stationary wave heat flux, and springtime vortex breakup. A dynamical mechanism is proposed whereby increased surface roughness leads to improved stationary waves. Increased surface roughness leads to anomalous eddy momentum flux convergence primarily in the Indian Ocean sector (where eddies are strongest climatologically) in September and October. The localization of the eddy momentum flux convergence anomaly in the Indian Ocean sector leads to a zonally asymmetric reduction in zonal wind and, by geostrophy, to a wavenumber-1 stationary wave pattern. This tropospheric stationary wave pattern leads to enhanced upwards wave activity entering the stratosphere. The net effect is an improved Southern Hemisphere vortex: the vortex breaks up earlier in spring (i.e., the spring late-breakup bias is partially ameliorated) yet is no weaker in mid-winter. More than half of the stratospheric biases appear to be related to the surface wind speed biases. As many other chemistry climate models use a similar scheme for their surface layer momentum exchange and have similar biases in the stratosphere, we expect that results from GEOSCCM may be relevant for other climate models.

  5. In vitro performance testing of the novel Medspray wet aerosol inhaler based on the principle of Rayleigh break-up.

    Science.gov (United States)

    de Boer, Anne H; Wissink, Jeroen; Hagedoorn, Paul; Heskamp, Iwan; de Kruijf, Wilbur; Bünder, Ralf; Zanen, Pieter; Munnik, Paul; van Rijn, Cees; Frijlink, Henderik W

    2008-05-01

    A new inhaler (Medspray) for pulmonary drug delivery based on the principle of Rayleigh break-up has been tested with three different spray nozzles (1.5; 2.0 and 2.5 mum) using aqueous 0.1% (w/w) salbutamol and 0.9% (w/w) sodium chloride solutions. Particle size distributions in the aerosol were measured with the principles of time of flight (APS) and laser diffraction (LDA). The Medspray inhaler exhibits a highly constant droplet size distribution in the aerosol during dose emission. Droplets on the basis of Rayleigh break-up theory are monodisperse, but due to some coalescence the aerosols from the Medspray inhaler are slightly polydisperse. Mass median aerodynamic diameters at 60 l.min(-1) from APS are 1.42; 1.32 and 1.27 times the theoretical droplet diameters (TD's) and median laser diffraction diameters are 1.29; 1.14 and 1.05 times TD for 1.5; 2.0 and 2.5 mum nozzles (TD: 2.84; 3.78 and 4.73 mum respectively). The narrow particle size distribution in the aerosol from the Medspray is highly reproducible for the range of flow rates from 30 to 60 l.min(-1). The mass median aerodynamic droplet diameter can be well controlled within the size range from 4 to 6 mum at 60 l.min(-1).

  6. Marital satisfaction and break-ups differ across on-line and off-line meeting venues.

    Science.gov (United States)

    Cacioppo, John T; Cacioppo, Stephanie; Gonzaga, Gian C; Ogburn, Elizabeth L; VanderWeele, Tyler J

    2013-06-18

    Marital discord is costly to children, families, and communities. The advent of the Internet, social networking, and on-line dating has affected how people meet future spouses, but little is known about the prevalence or outcomes of these marriages or the demographics of those involved. We addressed these questions in a nationally representative sample of 19,131 respondents who married between 2005 and 2012. Results indicate that more than one-third of marriages in America now begin on-line. In addition, marriages that began on-line, when compared with those that began through traditional off-line venues, were slightly less likely to result in a marital break-up (separation or divorce) and were associated with slightly higher marital satisfaction among those respondents who remained married. Demographic differences were identified between respondents who met their spouse through on-line vs. traditional off-line venues, but the findings for marital break-up and marital satisfaction remained significant after statistically controlling for these differences. These data suggest that the Internet may be altering the dynamics and outcomes of marriage itself.

  7. Coal-water slurry sprays from an electronically controlled accumulator fuel injection system: Break-up distances and times

    Energy Technology Data Exchange (ETDEWEB)

    Caton, J.A.; Payne, S.E.; Terracina, D.P.; Kihm, K.D. [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering

    1993-12-31

    Experiments have been completed to characterize coal-water slurry sprays from an electronically-controlled accumulator fuel injection system of a diesel engine. The sprays were injected into a pressurized chamber equipped with windows. High speed movies, fuel pressures and needle lifts were obtained as a function of time, orifice diameter, coal loading, gas density in the chamber, and accumulator fuel pressure. For the base conditions (50% (by man) coal loading, 0.4 mm diameter nozzle hole, coal-water slurry pressure of 82 MPa (12,000 psi), and a chamber density of 25 kg/m{sup 3}), the break-up time was 0.30 ms. An empirical correlation for spray tip penetration, break-up time and initial jet velocity was developed. For the conditions of this study, the spray tip penetration and initial jet velocity were 15% greater for coal-water slurry than for diesel fuel or water. Results of this study and the correlation are specific to the tested coal-water slurry and are not general for other coal-water slurry fuels.

  8. Movement of a female polar bear (Ursus maritimus) in the Kara Sea during the summer sea-ice break-up.

    Science.gov (United States)

    Rozhnov, V V; Platonov, N G; Naidenko, S V; Mordvintsev, I N; Ivanov, E A

    2017-01-01

    The polar bear movement trajectory in relation to onset date of the sea-ice break-up was studied in the coastal zone of the Taimyr Peninsula, eastern part of the Kara Sea, using as an example a female polar bear tagged by a radio collar with an Argos satellite transmitter. Analysis of the long-term pattern of ice melting and tracking, by means of satellite telemetry, of the female polar bear who followed the ice-edge outgoing in the north-eastern direction (in summer 2012) suggests that direction of the polar bear movement depends precisely on the direction of the sea-ice cover break-up.

  9. Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica)

    OpenAIRE

    Riaux-Gobin, C.; Poulin, M.; Dieckmann, Gerhard; Labrune, C.; Vétion, G.

    2011-01-01

    The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cyl...

  10. Informing neutron capture nucleosynthesis on short-lived nuclei with (d,p) reactions

    Science.gov (United States)

    Cizewski, Jolie A.; Ratkiewicz, Andrew; Escher, Jutta E.; Lepailleur, Alexandre; Pain, Steven D.; Potel, Gregory

    2018-01-01

    Neutron capture on unstable nuclei is important in understanding abundances in r-process nucleosynthesis. Previously, the non-elastic breakup of the deuteron in the (d,p) reaction has been shown to provide a neutron that can be captured by the nucleus and the gamma-ray decay of the subsequent compound nucleus can be modelled to predict the gamma-ray decay of the compound nucleus in the (n,γ) reaction. Preliminary results from the 95Mo(d,pγ) reaction in normal kinematics support the (d,pγ) reaction as a valid surrogate for neutron capture. The techniques to measure the (d,pγ) reaction in inverse kinematics have been developed.

  11. Effects of earlier sea ice breakup on survival and population size of polar bears in western Hudson Bay

    Science.gov (United States)

    Regehr, E.V.; Lunn, N.J.; Amstrup, Steven C.; Stirling, I.

    2007-01-01

    Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population-level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack-Jolly-Seber capture-recapture models to estimate population size and survival for polar bears (Ursus maritimus), one of the most ice-dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020-1,368) in 1987 to 935 (95% CI = 794-1,076) in 2004. Total apparent survival of prime-adult polar bears (5-19 yr) was stable for females (0.93; 95% CI = 0.91-0.94) and males (0.90; 95% CI = 0.88-0.91). Survival of juvenile, subadult, and senescent-adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human-polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as

  12. Eastern Gondwana breakup and the Lord Howe Rise continental ribbon from multi-channel seismic reflection data

    Science.gov (United States)

    Boston, Brian; Nakamura, Yasuyuki; Kodaira, Shuichi; Miura, Seiichi; Gallais, Flora; Fujie, Gou; Kaiho, Yuka; Hackney, Ron; Yamada, Yasuhiro; Saito, Saneatsu; Shiraishi, Kazuya; Nichol, Scott; Bernardel, George; Mitchell, Cameron

    2017-04-01

    The eastern Australian margin of Gondwana rifted during the Late Cretaceous, forming the Lord Howe Rise continental ribbon. This breakup is still poorly understood with only a few regional studies and suggested formation processes that range from a plume impinging on the lithosphere to upper-plate extension associated with slab rollback. This project uses data collected on a multi-leg geophysical cruise undertaken in 2016 to study the rifting processes at the Lord Howe Rise. This project uses a regional 900 km long east-west oriented profile at 27.2°S with both multi-channel seismic reflection and multibeam bathymetry datasets. We present processed pre-stack depth migrated seismic reflection images and interpretations to show the structure and evolution of this margin from the oceanic Tasman Basin in the west to the extended continental crust of the Lord Howe Rise in the east. The Tasman Basin contains buried basins only on its eastern side. These basins may be related to early transform faulting. The Lord Howe Rise contains both syn-rift and post-rift sedimentary sequences in multiple basins that record the breakup of the margin. Between these two regions are the Dampier Ridge and Middleton Basin. The boundary between the Dampier Ridge and Tasman Basin is a very sharp feature that is unlike any other boundary in the area. This sharp boundary may represent a transform segment. Within the Dampier Ridge, there are multiple rift basins up to 3 km deep that are similar to those on the Lord Howe Rise. In contrast, the Middleton Basin that separates the Dampier Ridge and the Lord Howe Rise is a broad, well-stratified sedimentary basin of up to 3.5 km thick and contains an unconformity that separates deeper sedimentary strata that are conformable with the basement and younger strata that filled the basin post-rifting. These new results indicate a dynamic process and history during the breakup of eastern Gondwana that led to the opening of the Tasman Basin and formation

  13. CFD Simulations of an Air-Water Bubble Column: Effect of Luo Coalescence Parameter and Breakup Kernels.

    Science.gov (United States)

    Syed, Alizeb Hussain; Boulet, Micael; Melchiori, Tommaso; Lavoie, Jean-Michel

    2017-01-01

    In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 and 0.038 m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM) was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0) from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a) A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo) combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b) A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr) was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c) A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d) The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for simulating

  14. CFD Simulation of an Air-Water Bubble Column: Effect of Luo coalescence parameter and breakup kernels

    Science.gov (United States)

    Syed, Alizeb Hussain; Boulet, Micael; Melchiori, Tommaso; Lavoie, Jean-Michel

    2017-09-01

    In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 m/s and 0.038m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM) was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0) from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a) A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo) combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b) A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr) was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c) A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d) The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for simulating

  15. CFD Simulations of an Air-Water Bubble Column: Effect of Luo Coalescence Parameter and Breakup Kernels

    Directory of Open Access Journals (Sweden)

    Alizeb Hussain Syed

    2017-09-01

    Full Text Available In this work, CFD simulations of an air-water bubbling column were performed and validated with experimental data. The superficial gas velocities used for the experiments were 0.019 and 0.038 m/s and were considered as an homogeneous regime. The former involves simpler physics when compared to a heterogeneous regime where the superficial velocities are higher. In order to simulate the system, a population balance model (PBM was solved numerically using a discrete method and a closure kernels involving the Luo coalescence model as well as two different breakup models: Luo's and Lehr's. For the multi-phase calculations, an eulerian framework was selected and the interphase momentum transfer included drag, lift, wall lubrication, and turbulent dispersion terms. A sensitivity analysis was performed on a Luo coalescence kernel by changing the coalescence parameter (c0 from 1.1 to 0.1 and results showed that the radial profiles of gas holdup and axial liquid velocity were significantly affected by such parameter. From the simulation results, the main conclusions were: (a A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo combined with a decreasing value of c0 improves the gas holdup profiles as compared to empirical values. However, at the lowest value of c0 investigated in this work, the axial liquid velocity deteriorates with regards to experimental data when using a superficial gas velocity of 0.019 m/s. (b A combination of the Luo coalescence and Lehr breakup models (Luo-Lehr was shown to improve the gas holdup values with experimental data when compared to the Luo-Luo kernels. However, as c0 decreases, the Luo-Lehr models underestimate the axial liquid velocity profiles with regards to empirical values. (c A first and second order numerical schemes allowed predicting similar radial profiles of gas holdup and axial liquid velocity. (d The mesh sensitivity results show that a 3 mm mesh size can be considered as reasonable for

  16. In medium fragment break-up of projectile in 58Ar+36Ni central collisions

    Science.gov (United States)

    Francalanza, L.

    2017-06-01

    Latest results concerning the study of central collisions in 36Ar+58Ni reactions, carried out by using the INDRA 4π detector at the GANIL are presented. Reaction mechanisms involved in very central collisions for such asymmetric system and their evolution as function of incident energy are studied, from 32 to 95 AMeV, suggesting an in-medium “break-up” process of the projectile where the presence of nuclear transparency plays an important role. Such a process, leading to forward emission of fragments and lights particles in the laboratory frame, is found to be more and more relevant at high energies, when the contribution from quasi-fusion processes vanishes. Evidences of emissions from an excited quasi-target (QT*), moving along the beam direction with velocity rising with incident energy under the dragging effect of the in-medium “crumbling” of the projectile are highlighted.

  17. Mathematics Curriculum Changes in Republic of Serbia for Grades 5-8 After the Break-Up of Socialist Federal Republic of Yugoslavia

    Science.gov (United States)

    Vlajic, Jovana

    2011-01-01

    The purpose of this study was to determine the changes in the mathematics curriculum for grades 5-8 in the Republic of Serbia after the break-up of SFRY. In particular, the research sought to identify the changes in the mathematics curriculum in terms of curriculum content and learning objectives, textbooks, and high school entrance examination…

  18. Flocculation and floc break-up related to tidally induced turbulent shear in a low-turbidity, microtidal estuary

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest

    2014-01-01

    . The asymmetrical, flood-dominated tidal wave showed how longer periods of low turbulent shear enhanced the hysteresis. The study demonstrates how the combination of the two deployment types will give a more adequate description of the flocculation dynamics over tidal cycles. Moreover, it shows the importance...... the dynamics on a short temporal scale (cycle) in the frame of the entire water column in the first campaign. In the second campaign the instruments were moored (Eulerian deployment) to get information on a longer temporal scale (> tidal cycle). The quasi-Lagrangian measurements showed strong...... flocculation and floc break-up dynamics in the lower part of the water column in the period around slack water. These dynamics were confirmed in the Eulerian deployments and were reoccurring in every tidal cycle. The dynamics were mostly governed by changes in turbulent shear. Strong microflocs with a lower...

  19. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  20. High-speed, two-dimensional synchrotron white-beam x-ray radiography of spray breakup and atomization

    Energy Technology Data Exchange (ETDEWEB)

    Halls, Benjamin R.; Radke, Christopher D.; Reuter, Benjamin J.; Kastengren, Alan L.; Gord, James R.; Meyer, Terrence R.

    2017-01-01

    High-speed, two-dimensional synchrotron x-ray radiography and phase-contrast imaging are demonstrated in propulsion sprays. Measurements are performed at the 7-BM beamline at the Advanced Photon Source user facility at Argonne National Laboratory using a recently developed broadband x-ray white beam. This novel enhancement allows for high speed, high fidelity x-ray imaging for the community at large. Quantitative path-integrated liquid distributions and spatio-temporal dynamics of the sprays were imaged with a LuAG:Ce scintillator optically coupled to a high-speed CMOS camera. Images are collected with a microscope objective at frame rates of 20 kHz and with a macro lens at 120 kHz, achieving spatial resolutions of 12 μm and 65 μm, respectively. Imaging with and without potassium iodide (KI) as a contrast-enhancing agent is compared, and the effects of broadband attenuation and spatial beam characteristics are determined through modeling and experimental calibration. In addition, phase contrast is used to differentiate liquid streams with varying concentrations of KI. The experimental approach is applied to different spray conditions, including quantitative measurements of mass distribution during primary atomization and qualitative visualization of turbulent binary fluid mixing. High-speed, two-dimensional synchrotron white-beam x-ray radiography of spray breakup and atomization. Available from: https://www.researchgate.net/publication/312567827_High-speed_two-dimensional_synchrotron_white-beam_x-ray_radiography_of_spray_breakup_and_atomization [accessed Aug 31, 2017].

  1. New constraints on the age and style of continental breakup in the South Atlantic from magnetic anomaly data

    Science.gov (United States)

    Collier, Jenny S.; McDermott, Carl; Warner, George; Gyori, Noemi; Schnabel, Michael; McDermott, Ken; Horn, Brian W.

    2017-11-01

    We present new constraints on the opening of the South Atlantic Ocean from a joint interpretation of marine magnetic anomaly grids and forward modelling of conjugate profiles. We use 45,000 km of recently collected commercial ship track data combined with 561,000 km of publically available data. The new data cover the critical ocean-continental transition zones and allow us to identify and downgrade some poorly navigated older ship tracks relied upon in earlier compilations. Within the final grids the mean cross-over error is 14 nT computed from 8,227 ship track intersections. The forward modelling used uniformly magnetised bodies whose shapes were constrained from coincident deep-seismic reflection data. We find the oldest magnetic anomalies to date from M10r (134.2 Ma, late Valanginian) north of the Falkland-Agulhas Fracture Zone and M3 (129.3 Ma, Barremian) south of the Rio Grande Fracture Zone. Hence, assuming the GPTS used is correct, continental breakup was contemporaneous with the Parana and Etendeka continental flood basalts. Many of the landward linear anomalies overlap seismically mapped Seaward Dipping Reflectors (SDRs). We interpret this to mean that a significant portion of the SDRs overlay crust formed by subaerial seafloor spreading. Here crustal accretion is envisaged to be similar to that at mid-ocean ridges, but sheet lava flows (that later form the SDRs) rather than pillow basalts form the extrusive component. Segmentation of the linear anomalies generated implies that this stage of continental breakup is organised and parallels the seafloor spreading centre that follows. Our results call into question the common assumption that at volcanic continental margins the first linear magnetic anomalies represent the start of conventional (submarine) oceanic crustal generation.

  2. Breakup and reestablishment of the armour layer in a large gravel-bed river below dams: The lower Ebro

    Science.gov (United States)

    Vericat, Damia; Batalla, Ramon J.; Garcia, Celso

    2006-06-01

    Changes in armour layer during floods under supply limited conditions are little known. This paper describes the breakup and the reestablishment of the bed armour layer in the regulated gravel-bed Ebro River during a flooding period. The study was conducted over a 28-km study reach from 2002 to 2004. The surface, subsurface and bed load grain size distribution constitute the bases for the analysis of bed-armouring dynamics. The results indicate that the magnitude of floods controlled the degree of armouring of the river bed. The initial mean armouring ratio was 2.3, with maximum values reaching 4.4. Floods in the winter of 2002-2003 ( Q8) caused the breakup of the armour layer in several sections. This resulted in the erratic bed load pattern observed during the December 2002 flushing flow and in the increase in bed load transport during successive events. Most grain size classes were entrained and transported, causing river bed incision. The mean armouring ratio decreased to 1.9. In contrast, during low magnitude floods in 2003-2004 ( Q2), the coarsest fractions (64 mm) did not take part in the bed load while finer particles were winnowed, thus surface deposits coarsened. As a result, the armour layer was reestablished (i.e., the mean armouring ratio increased to 2.3), and the supply of subsurface sediment decreased. The supply and transport of bed material appear to be in balance in the river reach immediately below the dam. In contrast, the transport of medium and finer size classes in the downstream reaches was higher than their supply from upstream, a phenomenon that progressively reduced their availability in the river bed surface, hence the armour layer reworking.

  3. Botulinum hemagglutinin-mediated in situ break-up of human induced pluripotent stem cell aggregates for high-density suspension culture.

    Science.gov (United States)

    Nath, Suman C; Tokura, Tomohiro; Kim, Mee-Hae; Kino-Oka, Masahiro

    2018-04-01

    Large numbers of human induced pluripotent stem cells (hiPSCs) are required for making stable cell bank. Although suspension culture yields high cell numbers, there remain unresolved challenges for obtaining high-density of hiPSCs because large size aggregates exhibit low growth rates. Here, we established a simple method for hiPSC aggregate break-up using botulinum hemagglutinin (HA), which specifically bound with E-cadherin and disrupted cell-cell connections in hiPSC aggregates. HA showed temporary activity for disrupting the E-cadherin-mediated cell-cell connections to facilitate the break-up of aggregates into small sizes only 9 hr after HA addition. The transportation of HA into the aggregates was mediated by transcellular and paracellular way after HA addition to the culture medium. hiPSC aggregates broken up by HA showed a higher number of live cells, higher cell density, and higher expansion fold compared to those of aggregates dissociated with enzymatic digestion. Moreover, a maximum cell density of 4.5 ± 0.2 × 10 6 cells ml -1 was obtained by aggregate break-up into small ones, which was three times higher than that with the conventional culture without aggregate break-up. Therefore, the temporary activity of HA for disrupting E-cadherin-mediated cell-cell connection was key to establishing a simple in situ method for hiPSC aggregate break-up in bioreactors, leading to high cell density in suspension culture. © 2017 Wiley Periodicals, Inc.

  4. Proton induced deuteron break-up with emission of a fast forward proton pair

    CERN Document Server

    Dymov, S; Erven, W; Hartmann, M; Kacharava, A K; Khoukaz, A; Klehr, F; Koch, R; Komarov, V; Kulikov, A; Kurbatov, V; Lang, N; Macharashvili, G; Maier, R; Merzlyakov, S I

    2003-01-01

    A kinematically complete study of the pd yields (pp)//sn reaction with forward emission of an S-wave proton pair (pp), has been performed at six beam energies 0.6, 0.7, 0.8, 0.95, 1.35 and 1.9 GeV. The experiment was carried out at the ANKE spectrometer installed at the internal beam of the proton synchrotron COSY (Julich). The 3- momenta of both final state protons have been measured and events with a relative proton energy less than 3 MeV were selected as **1S //0 diprotons. The differential cross sections of such pair production averaged over the c.m. polar angle of the total momentum of the pair in the range 0 degree -8.1 degree have been obtained. A comparison of the result with a theoretical model based on the mechanism of pd-backward elastic scattering is described as well. 17 Refs.

  5. Break-up of stepped platinum catalyst surfaces by high CO coverage.

    Science.gov (United States)

    Tao, Feng; Dag, Sefa; Wang, Lin-Wang; Liu, Zhi; Butcher, Derek R; Bluhm, Hendrik; Salmeron, Miquel; Somorjai, Gabor A

    2010-02-12

    Stepped single-crystal surfaces are viewed as models of real catalysts, which consist of small metal particles exposing a large number of low-coordination sites. We found that stepped platinum (Pt) surfaces can undergo extensive and reversible restructuring when exposed to carbon monoxide (CO) at pressures above 0.1 torr. Scanning tunneling microscopy and photoelectron spectroscopy studies under gaseous environments near ambient pressure at room temperature revealed that as the CO surface coverage approaches 100%, the originally flat terraces of (557) and (332) oriented Pt crystals break up into nanometer-sized clusters and revert to the initial morphology after pumping out the CO gas. Density functional theory calculations provide a rationale for the observations whereby the creation of increased concentrations of low-coordination Pt edge sites in the formed nanoclusters relieves the strong CO-CO repulsion in the highly compressed adsorbate film. This restructuring phenomenon has important implications for heterogeneous catalytic reactions.

  6. Visualization of Atomization Gas Flow and Melt Break-up Effects in Response to Nozzle Design

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver; Rieken, Joel; Meyer, John; Byrd, David; Heidloff, Andy

    2011-04-01

    Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a slotted trumpet bell pour tube was not clearly demonstrated in the current experiments, perhaps confounded by the influence of the melt oxidation reaction that occurred simultaneously with the atomization process. For this GARS variation of close-coupled gas atomization, it may be best to utilize the straight cylindrical pour tube and closed wake operation of an atomization nozzle with higher gas mass flow to promote the maximum yields of ultrafine powders that are preferred for the oxide dispersion strengthened alloys made from these powders.

  7. Recent developments in fusion and direct reactions with weakly bound nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Canto, L.F. [Instituto de Física, Universidade Federal do Rio de Janeiro, C.P. 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Instituto de Física, Universidade Federal Fluminense, Av. Litorânea S-N, 24210-340 Niteroi, RJ (Brazil); Gomes, P.R.S. [Instituto de Física, Universidade Federal Fluminense, Av. Litorânea S-N, 24210-340 Niteroi, RJ (Brazil); Donangelo, R. [Instituto de Física, Universidade Federal do Rio de Janeiro, C.P. 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Instituto de Física, Facultad de Ingeniería, C.C. 30, 11000 Montevideo (Uruguay); Lubian, J. [Instituto de Física, Universidade Federal Fluminense, Av. Litorânea S-N, 24210-340 Niteroi, RJ (Brazil); Hussein, M.S., E-mail: hussein@if.usp.br [Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970, São Paulo, SP (Brazil); Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, C.P. 66318, 05314-970, São Paulo, SP (Brazil); Departamento de Física, Instituto Tecnológico de Aeronáutica, DCTA 12.228-900, São José dos Campos, SP (Brazil)

    2015-09-20

    In this Report we give a balanced account of the experimental and theoretical advances acquired over the last decade in the field of near-barrier fusion reactions induced by weakly bound stable and unstable nuclei. The elastic scattering and breakup reactions of these systems are also extensively reviewed as they play an important role in the fusion process. We review several theoretical tools used in the description of the data. The concepts of Complete Fusion (CF), Incomplete Fusion (ICF) and Total Fusion (TF), which is the sum of CF and ICF, are discussed and recent work on the calculation of these quantities is reviewed. The Continuum Discretized Coupled Channels (CDCC) method and its semiclassical version are described in detail and their limitations are pointed out. More importantly, we describe the salient features of the conclusions reached from the more than 40 measurements made, over a decade, of near-barrier fusion, elastic scattering and breakup reactions, and confront these data with the CDCC or other methods appropriate for these processes at the energy regime in question.

  8. Design and Fabrication of DebriSat - A Representative LEO Satellite for Improvements to Standard Satellite Breakup Models

    Science.gov (United States)

    Clark, S.; Dietrich, A.; Fitz-Coy, N.; Weremeyer, M.; Liou, J.-C.

    2012-01-01

    This paper discusses the design and fabrication of DebriSat, a 50 kg satellite developed to be representative of a modern low Earth orbit satellite in terms of its components, materials used, and fabrication procedures. DebriSat will be the target of a future hypervelocity impact experiment to determine the physical characteristics of debris generated after an on-orbit collision of a modern LEO satellite. The major ground-based satellite impact experiment used by DoD and NASA in their development of satellite breakup models was SOCIT, conducted in 1992. The target used for that experiment was a Navy transit satellite (40 cm, 35 kg) fabricated in the 1960's. Modern satellites are very different in materials and construction techniques than those built 40 years ago. Therefore, there is a need to conduct a similar experiment using a modern target satellite to improve the fidelity of the satellite breakup models. To ensure that DebriSat is truly representative of typical LEO missions, a comprehensive study of historical LEO satellite designs and missions within the past 15 years for satellites ranging from 1 kg to 5000 kg was conducted. This study identified modern trends in hardware, material, and construction practices utilized in recent LEO missions. Although DebriSat is an engineering model, specific attention is placed on the quality, type, and quantity of the materials used in its fabrication to ensure the integrity of the outcome. With the exception of software, all other aspects of the satellite s design, fabrication, and assembly integration and testing will be as rigorous as that of an actual flight vehicle. For example, to simulate survivability of launch loads, DebriSat will be subjected to a vibration test. As well, the satellite will undergo thermal vacuum tests to verify that the components and overall systems meet typical environmental standards. Proper assembly and integration techniques will involve comprehensive joint analysis, including the precise

  9. Revised model of the East Gondwana Break-up and formation of the Gateway between India and Antarctica

    Science.gov (United States)

    Leitchenkov, German; Guseva, Julia; Ivanov, Sergey; Golynsky, Alexander

    2017-04-01

    The history of break-up and sea-floor spreading between India and Antarctica long remained vague mainly because of the data scarcity off both continents. Geophysical studies carried out recently in the Enderby Basin (Southern Indian Ocean) provided new information and advanced our knowledge on this problem. Magnetic surveys discovered there a prominent linear high-amplitude bipolar magnetic anomaly (HBMA), which stretched more than 1000 km westward from the southern Kerguelen Plateau. This anomaly was interpreted by many as the contact between stretched continental crust and oceanic crust. Gaina et al. (1987) suggested the existence of an abandoned spreading centre in the eastern Enderby Basin and inferred that the Elan Bank (established as a microcontinent) was isolated from the India margin by a ridge jump at about M0 chron (c. 120 Ma). South of an abandoned spreading centre, they identified a series of magnetic anomalies from M2 to M9. New magnetic data collected in the western Enderby Basin and revision of all available geophysical data gives a new notion on the geodynamics of the East Gondwana break-up and separation of India from Antarctica. According to a new model, the HBMA corresponds to M34o chrone and its increased intensity can be explained by the emplacement of the Kerguelen Hotspot and thickening of the oceanic (magmatic) crust at that time. A relationship between hot-spots and appearance of high-amplitude magnetic anomalies is observed elsewhere in the World Ocean. In our model, the continent-ocean boundary is located about 150 km landward of the HBMA, and anomalies from M4 to M0 are identified between these features. The ridge jump (which isolated the Elan Bank) occurred about 110 Ma ago when the Kerguelen Hotspot moved toward the India margin. This model is consistent with the interpretation of sea-floor spreading history off Western Australia. An earlier (around 120 Ma) ridge jump probably occurred in the area of the southern Kerguelen Plateau

  10. Female partner's perception of premature ejaculation and its impact on relationship breakups, relationship quality, and sexual satisfaction.

    Science.gov (United States)

    Burri, Andrea; Giuliano, François; McMahon, Chris; Porst, Hartmut

    2014-09-01

    Women's perceptions of the men's ejaculatory behavior, as well as the impact premature ejaculation (PE) has on the couple's functioning, are important factors that need to be considered. This survey investigated women's perception and importance of ejaculatory function, as well as the specific aspects of PE that cause distress. In addition, the survey further identified the factors with a greater impact on intimacy, relationship, and sexual behavior. The 1,463 females belonging to a web panel from three different countries (Mexico, Italy, and South Korea), aged 20-50 years, participated in the survey. A combination of validated and self-constructed questionnaires to assess women's perception of PE, relationship satisfaction and quality, and sexual functioning and satisfaction were used. Descriptive statistics in form of proportions and percentages, correlation, and regression analyses. A significant correlation between the importance of ejaculatory control and felt distress could be observed (rho = 0.55, P < 0.001). Women reporting less sexual problems considered ejaculatory control more important and reported more PE-related distress (rho = 0.23 and 0.11, respectively; P < 0.001 for both). The male's lack of attention and focus on performance was the most frequently reported reasons for sexual distress (47.6%) followed by "the short time between penetration and ejaculation" (39.9%), and "the lack of ejaculatory control" (24.1%). Almost a quarter of women reported that the man's ejaculatory problem had previously led to relationship breakups (22.8%). Women considering duration to be important were more likely to report breakups. The study highlights the detrimental effects of PE on relationship and sexual satisfaction in the female partner and how it can lead to the termination of the relationship. Most notably, this is the first study to report that an important source of female distress are not only parameters related to performance such as

  11. Two-Photon Interactions with Nuclear Breakup in Relativistic Heavy Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Baltz, Anthony J.; Gorbunov, Yuri; R Klein, Spencer; Nystrand, Joakim

    2010-07-07

    Highly charged relativistic heavy ions have high cross-sections for two-photon interactions. The photon flux is high enough that two-photon interactions may be accompanied by additional photonuclear interactions. Except for the shared impact parameter, these interactions are independent. Additional interactions like mutual Coulomb excitation are of experimental interest, since the neutrons from the nuclear dissociation provide a simple, relatively unbiased trigger. We calculate the cross sections, rapidity, mass and transverse momentum (p{sub T}) distributions for exclusive {gamma}{gamma} production of mesons and lepton pairs, and for {gamma}{gamma} reactions accompanied by mutual Coulomb dissociation. The cross-sections for {gamma}{gamma} interactions accompanied by multiple neutron emission (XnXn) and single neutron emission (1n1n) are about 1/10 and 1/100 of that for the unaccompanied {gamma}{gamma} interactions. We discuss the accuracy with which these cross-sections may be calculated. The typical p{sub T} of {gamma}{gamma} final states is several times smaller than for comparable coherent photonuclear interactions, so p{sub T} may be an effective tool for separating the two classes of interactions.

  12. A numerical method for integrating the kinetic equations of droplet spectra evolution by condensation/evaporation and by coalescence/breakup processes

    Science.gov (United States)

    Emukashvily, I. M.

    1982-01-01

    An extension of the method of moments is developed for the numerical integration of the kinetic equations of droplet spectra evolution by condensation/evaporation and by coalescence/breakup processes. The number density function n sub k (x,t) in each separate droplet packet between droplet mass grid points (x sub k, x sub k+1) is represented by an expansion in orthogonal polynomials with a given weighting function. In this way droplet number concentrations, liquid water contents and other moments in each droplet packet are conserved and the problem of solving the kinetic equations is replaced by one of solving a set of coupled differential equations for the number density function moments. The method is tested against analytic solutions of the corresponding kinetic equations. Numerical results are obtained for different coalescence/breakup and condensation/evaporation kernels and for different initial droplet spectra. Also droplet mass grid intervals, weighting functions, and time steps are varied.

  13. Low-energy deuteron-induced reactions on 93Nb

    Science.gov (United States)

    Avrigeanu, M.; Avrigeanu, V.; Bém, P.; Fischer, U.; Honusek, M.; Koning, A. J.; Mrázek, J.; Šimečková, E.; Štefánik, M.; Závorka, L.

    2013-07-01

    The activation cross sections of (d,p), (d,2n), (d,2np+nd+t), (d,2nα), and (d,pα) reactions on 93Nb were measured in the energy range from 1 to 20 MeV using the stacked-foil technique. Then, within a simultaneous analysis of elastic scattering and reaction data, the available elastic-scattering data analysis was carried out in order to obtain the optical potential for reaction cross-section calculations. Particular attention was paid to the description of the breakup mechanism and direct reaction stripping and pick-up, followed by pre-equilibrium and compound-nucleus calculations. The measured cross sections as well as all available deuteron activation data of 93Nb were compared with results of local model calculations carried out using the codes fresco and stapre-h and both default and particular predictions of the code talys-1.4 and tendl-2012-evaluated data.

  14. Development and validation of models for bubble coalescence and breakup. Final report; Entwicklung und Validierung von Modellen fuer Blasenkoaleszenz und -zerfall. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Y.; Lucas, D.

    2013-02-15

    A new generalized model for bubble coalescence and breakup has been developed. It is based on physical considerations and takes into account various mechanisms that can lead to bubble coalescence and breakup. First, in a detailed literature review, the available models were compiled and analyzed. It turned out that many of them show a contradictory behaviour. None of these models allows the prediction of the evolution of bubble size distributions along a pipe flow for a wide range of combinations of flow rates of the gas and the liquid phase. The new model has been extensively studied in a simplified Test-Solver. Although this does not cover all details of a developing flow along the pipe, it allows - in contrast to a CFD code - to conduct a large number of variational calculations to investigate the influence of individual sizes and models. Coalescence and breakup cannot be considered separately from other phenomena and models that reflect these phenomena. There are close interactions with the turbulence of the liquid phase and the momentum exchange between phases. Since the dissipation rate of turbulent kinetic energy is a direct input parameter for the new model, the turbulence modelling has been studied very carefully. To validate the model, a special experimental series for air-water flows was used, conducted at the TOPFLOW facility in an 8-meter long DN200 pipe. The data are characterized by high quality and were produced within the TOPFLOW-II project. The test series aims to provide a basis for the work presented here. Predicting the evolution of the bubble size distribution along the pipe could be improved significantly in comparison to the previous standard models for bubble coalescence and breakup implemented in CFX. However some quantitative discrepancies remain. The full model equations as well as an implementation as ''User-FORTRAN'' in CFX are available and can be used for further work on the simulation of poly-disperse bubbly

  15. Simultaneous direct amplification and compression of picosecond pulses to 65-kW peak power without pulse break-up in erbium fiber.

    Science.gov (United States)

    Jasapara, J C; Andrejco, M J; Nicholson, J W; Yablon, A D; Várallyay, Z

    2007-12-24

    Picosecond pulses at 1.56 micro mm wavelength are directly amplified with a diffraction limited beam quality in a core-pumped Er fiber with an 875 micro m(2) effective area. The interplay between nonlinear spectral broadening and anomalous fiber dispersion compresses the input pulse duration during amplification so that 42 nJ energy pulses with approximately 65 kW peak power are achieved without pulse break-up.

  16. Pangaea amalgamation and break-up: new radiometric constraints on sediment provenance in late Carboniferous and late Triassic basins of SW Iberia

    OpenAIRE

    Pereira, M. francisco; Chichorro, Martim; Ribeiro, Carlos; Vilallonga, Filipa; Drost, Kerstin; Linnemann, Ulf; Hofmann, Mandy

    2011-01-01

    The subject of this provenance study are greywacke and sandstone strata that define a key unconformity in SW Iberia, where late Triassic strata (Algarve Basin) overlie previously deformed and metamorphosed late Carboniferous basement (South Portuguese Zone). This angular unconformity records the transition from Pangaea´s amalgamation to its break-up with: i) development of marine basins of Moscovian age with turbiditic sedimentation (Brejeira Formation; ca. 310-305 Ma); ii) post-305 Ma deform...

  17. The Fragmented Manihiki Plateau - Key Region for Understanding the Break-up of the "Super" Large Igneous Province Ontong Java Nui

    Science.gov (United States)

    Hochmuth, K.; Gohl, K.; Uenzelmann-Neben, G.; Werner, R.

    2014-12-01

    The Manihiki Plateau of the western Pacific is one of the world - wide greatest Large Igneous Province (LIP) on oceanic crust. It is assumed that the Manihiki Plateau was emplaced as the centerpiece of the "Super-LIP" Ontong Java Nui by multiple volcanic phases during the Cretaceous Magnetic Quiet Period. The subsequent break-up of Ontong Java Nui led to fragmentation of the Manihiki Plateau into three sub-plateaus, which all exhibit individual relicts of the "Super-LIP" break-up. We examine two deep crustal seismic refraction/wide-angle reflection profiles crossing the two largest sub-plateaus of the Manihiki Plateau, the Western Plateaus and the High Plateau. Modeling of P- and S-wave velocities reveals surprising differences in the crustal structure between the two sub-plateaus. Whereas the High Plateau shows a constant crustal thickness of 20 km, relicts of multiple volcanic phases and break-up features at its margins, the model of the Western Plateaus reveals a crustal thickness decreasing from 17 km to only 9 km. There is only little evidence of secondary phases of volcanic activity. The main upper crustal structure on the Western Plateaus consists of fault systems and sedimentary basins. We infer that the High Plateau experienced phases of strong secondary volcanism, and that tectonic deformation was limited to its edges. The Western Plateaus, on the contrary, were deformed by crustal stretching and underwent only little to no secondary volcanism. This indicates that the two main sub-plateaus of the Manihiki Plateau experienced a different geological history and have played their individual parts in the break-up history of Ontong Java Nui.

  18. Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA.

    Science.gov (United States)

    Rozitis, Ben; MacLennan, Eric; Emery, Joshua P

    2014-08-14

    Space missions and ground-based observations have shown that some asteroids are loose collections of rubble rather than solid bodies. The physical behaviour of such 'rubble-pile' asteroids has been traditionally described using only gravitational and frictional forces within a granular material. Cohesive forces in the form of small van der Waals forces between constituent grains have recently been predicted to be important for small rubble piles (ten kilometres across or less), and could potentially explain fast rotation rates in the small-asteroid population. The strongest evidence so far has come from an analysis of the rotational breakup of the main-belt comet P/2013 R3 (ref. 7), although that was indirect and poorly constrained by observations. Here we report that the kilometre-sized asteroid (29075) 1950 DA (ref. 8) is a rubble pile that is rotating faster than is allowed by gravity and friction. We find that cohesive forces are required to prevent surface mass shedding and structural failure, and that the strengths of the forces are comparable to, though somewhat less than, the forces found between the grains of lunar regolith.

  19. Correlations among upper and lower tear menisci, noninvasive tear break-up time, and the Schirmer test.

    Science.gov (United States)

    Wang, Jianhua; Palakuru, Jayachandra R; Aquavella, James V

    2008-05-01

    To determine the relationships among tear meniscus parameters, noninvasive tear break-up time (NITBUT), and the Schirmer test. Experimental study. Thirty-six subjects were tested on one randomly selected eye. Real-time corneal optical coherence tomography (OCT) was used to image the upper and lower tear menisci during normal and delayed blinking followed by measurement of NITBUT and the Schirmer test. Digital images of the eye were taken for measuring the lid lengths to estimate tear volume in the menisci. Compared with normal blinking, significant increases of tear menisci occurred during delayed blinking (post hoc, P < .01). NITBUT was weakly but significantly correlated with the height (r = 0.36; P = .03) and area (r = 0.37; P = .03) of the lower tear meniscus during normal blinks. NITBUT was also correlated with the lower tear meniscus volume (r = 0.45; P < .05) and total tear meniscus volume (r = 0.43; P < .05) during normal blinking. The Schirmer test was not significantly related to any parameters of the tear menisci, volumes, or NITBUT; however, it was negatively correlated with the age of the subjects (r = -0.47; P = .004). The age was negatively correlated with the upper tear meniscus (r ranged from 0.36 to 0.37 for the radius, height, and area, P < .05) measured during delayed blinking. NITBUT appears correlated with the lower tear meniscus during normal blinking, and the Schirmer test appears not correlated with the noninvasively measured tear meniscus.

  20. Relationship of Corneal Pain Sensitivity With Dry Eye Symptoms in Dry Eye With Short Tear Break-Up Time.

    Science.gov (United States)

    Kaido, Minako; Kawashima, Motoko; Ishida, Reiko; Tsubota, Kazuo

    2016-03-01

    The purpose of this prospective comparative study was to investigate corneal sensitivity in subjects with unstable tear film, with and without dry eye (DE) symptoms. Forty-one eyes of 41 volunteers (mean age: 45.1 ± 9.4 years; age range, 23-57 years), with normal tear function and ocular surface except for tear stability, were studied. The eyes were divided into two groups depending on the presence or absence of DE symptoms: 21 eyes with DE symptoms (symptomatic group); and 20 eyes without DE symptoms (asymptomatic group). Three types of corneal sensitivity values were measured using a Cochet-Bonnet esthesiometer: the sensitivity for perception of touch (S-touch), the sensitivity for blinking (S-blink), and the sensitivity for pain (S-pain). Mean S-blink and S-pain were significantly higher in the symptomatic group than in the asymptomatic group (P 0.05). Corneal sensitivity for blinking and pain evoked by increased stimuli was higher in the symptomatic group (subjects with short break-up time DE) compared with subjects who have no DE symptoms despite decreased tear stability. The presence of both tear instability and hyperesthesia, rather than tear instability alone, may contribute to DE pathogenesis.

  1. The initial break-up of Pangæa elicited by Late Palæozoic deglaciation.

    Science.gov (United States)

    Yeh, Meng-Wan; Shellnutt, J Gregory

    2016-08-11

    The break-up of Pangæa was principally facilitated by tensional plate stress acting on pre-existing suture zones. The rifting of Pangæa began during the Early Permian along the southern Tethys margin and produced the lenticular-shaped continent known as Cimmeria. A mantle-plume model is ascribed to explain the rift-related volcanism but the NW-SE oriented Cimmerian rifts do not correlate well with pre-existing suture zones or 'structural heterogeneities' but appear to have a pertinent spatial and temporal association with Late Palæozoic glacial-interglacial cycles. Mantle potential temperature estimates of Cimmerian rift-related basalts (1410 °C ± 50 °C) are similar to ambient mantle conditions rather than an active mantle-plume rift as previously suggested. Moreover, we find that the distribution of glacial deposits shows significant temporal and spatial concurrence between the glacial retreat margins and rifting sites. We conclude that the location and timing of Cimmerian rifting resulted from the exploitation of structural heterogeneities within the crust that formed due to repeated glacial-interglacial cycles during the Late Palæozoic. Such effects of continental deglaciation helped to create the lenticular shape of Cimmeria and Neotethys Ocean suggesting that, in some instances, climate change may directly influence the location of rifting.

  2. The Effect of Hormone Replacement Therapy on Dry Eye Syndrome Evaluated with Schirmer Test and Break-Up Time.

    Science.gov (United States)

    Feng, Yanhong; Feng, Gang; Peng, Shuli; Li, Hui

    2015-01-01

    Hormone replacement therapy (HRT) for dry eye syndrome (DES) is controversial in clinical practice. The goal of this study was to review relevant studies and analyze the pooled data to determine whether HRT is effective for DES. In this study, a literature search of PubMed, Embase, and Cochrane databases up to May 2015 was performed, with the search restricted to English language publications. The studies were screened after reading the abstract and full text. Only studies related to the effect of HRT on DES were included in the meta-analysis. Results of Schirmer tests with and without anesthetics and tear break-up time (BUT) values data were extracted and entered into RevMan software to meta-analyze the overall effect of HRT on DES. A total of 43 studies were identified, and 21 of these studies were found to be related to the effect of HRT on DES. Ultimately, 5 studies were included in the final meta-analysis. The pooled results revealed that HRT can affect Schirmer test results without anesthetics but does not affect Schirmer test results with anesthetics and BUT. The results indicate that HRT might improve DES symptoms when measuring basal tear production without anesthesia.

  3. Effect of rebamipide ophthalmic suspension on optical quality in the short break-up time type of dry eye.

    Science.gov (United States)

    Koh, Shizuka; Inoue, Yasushi; Sugmimoto, Toshiki; Maeda, Naoyuki; Nishida, Kohji

    2013-09-01

    To determine the effect of rebamipide ophthalmic suspension on optical quality in patients with dry eye with short break-up time (BUT) of the tear film. Twenty-six eyes of 16 patients with the short BUT type of dry eye were enrolled and treated with 2% rebamipide ophthalmic suspension. At baseline and at 2 and 4 weeks after initiating the treatment, the serial corneal higher-order aberrations (HOAs), BUT, fluorescein staining, and Schirmer test were measured. Patients were asked to complete questionnaires about the changes in dry eye-related ocular symptoms after the treatment. Before the treatment, the pattern of postblink corneal HOAs for 10 seconds showed a sawtooth pattern, with a marked upward curve that increased after blinking. Treatment with rebamipide for 4 weeks significantly (P < 0.05) improved the postblink corneal HOAs and stabilized the pattern of the corneal HOAs. Significant increases in the tear film BUT were seen 2 and 4 weeks after the treatment (P < 0.001 for both comparisons). Rebamipide administered to treat the short BUT type of dry eye significantly improved optical quality because of the improvement in tear stability.

  4. Particle aerosolisation and break-up in dry powder inhalers: evaluation and modelling of impaction effects for agglomerated systems.

    Science.gov (United States)

    Wong, William; Fletcher, David F; Traini, Daniela; Chan, Hak-kim; Crapper, John; Young, Paul M

    2011-07-01

    This study utilised a combination of computational fluid dynamics (CFD) and standardised entrainment tubes to investigate the influence of impaction on the break-up and aerosol performance of a model inhalation formulation. A series of entrainment tubes, with different impaction plate angles were designed in silico and the flow characteristics, and particle tracks, were simulated using CFD. The apparatuses were constructed using three-dimensional printing. The deposition and aerosol performance of a model agglomerate system (496.3-789.2 μm agglomerates containing 3.91 μm median diameter mannitol particles) were evaluated by chemical analysis and laser diffraction, respectively. Analysis of the mannitol recovery from the assembly and CFD simulations indicated that mass deposition on the plate was dependent on the impactor angle (45°-90°) but independent of the airflow rate (60-140 L·min(-1)). In comparison, wall losses, perpendicular to the impactor plate were dependent on both the impactor angle and flow rate. Analysis of the particle size distribution exiting the impactor assembly suggested mannitol aerosolisation to be independent of impactor angle but dependent on the air velocity directly above the impactor plate. It is proposed that particle-wall impaction results in initial agglomerate fragmentation followed by reentrainment in the airstream above the impaction plate. Such observations have significant implications in the design of dry powder inhaler devices. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

  5. Relation of accommodative microfluctuation with dry eye symptoms in short tear break-up time dry eye.

    Science.gov (United States)

    Kaido, Minako; Kawashima, Motoko; Shigeno, Yuta; Yamada, Yoshiaki; Tsubota, Kazuo

    2017-01-01

    To investigate accommodative microfluctuations (AMFs) and visual function in short tear break-up time (BUT)-type dry eye (DE) and non-DE subjects. This prospective comparative study included 48 volunteers with DE symptoms (mean age 34.8 ± 5.5 years, age range 25-42 years) and 73 without DE symptoms (mean age 30.6 ± 4.7 years, age range 25-42 years). The eyes were divided into two groups: (1) DE group with DE symptoms and BUT ≤ 5 s and (2) non-DE group without DE symptoms and BUT > 5 s. We excluded eyes with Schirmer score ≤ 5 mm and positive keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA) examinations were performed. AMF parameters included total high-frequency component (HFC), HFC with low accommodation for the task of staring into the distance (HFC1), and HFC with high accommodation for deskwork (HFC2). Functional VA parameters included starting VA, functional VA, visual maintenance ratio, and blink frequency. A total of 33 and 34 eyes were categorized in the DE and non-DE groups, respectively. Mean blink frequency and HFC1 values were significantly higher in the DE group than they were in the non-DE group. DEs with symptoms showed abnormal AMF and visual function, which may be associated with DE symptoms.

  6. Dawn Auroral Breakup at Saturn Initiated by Auroral Arcs: UVIS/Cassini Beginning of Grand Finale Phase

    Science.gov (United States)

    Radioti, A.; Grodent, D.; Yao, Z. H.; Gérard, J.-C.; Badman, S. V.; Pryor, W.; Bonfond, B.

    2017-12-01

    We present Cassini auroral observations obtained on 11 November 2016 with the Ultraviolet Imaging Spectrograph at the beginning of the F-ring orbits and the Grand Finale phase of the mission. The spacecraft made a close approach to Saturn's southern pole and offered a remarkable view of the dayside and nightside aurora. With this sequence we identify, for the first time, the presence of dusk/midnight arcs, which are azimuthally spread from high to low latitudes, suggesting that their source region extends from the outer to middle/inner magnetosphere. The observed arcs could be auroral manifestations of plasma flows propagating toward the planet from the magnetotail, similar to terrestrial "auroral streamers." During the sequence the dawn auroral region brightens and expands poleward. We suggest that the dawn auroral breakup results from a combination of plasma instability and global-scale magnetic field reconfiguration, which is initiated by plasma flows propagating toward the planet. Alternatively, the dawn auroral enhancement could be triggered by tail magnetic reconnection.

  7. Rotation-induced YORP break-up of small bodies to produce post-main-sequence debris

    Science.gov (United States)

    Veras, D.; Jacobson, S. A.; Gänsicke, B. T.

    2017-09-01

    We hypothesize that the in situ break-up of small bodies such as asteroids spun to fission during the giant branch phases of stellar evolution provides an important contribution to the debris orbiting and ultimately polluting white dwarfs. The YORP (Yarkovsky-O'Keefe-Radviesvki-Paddock) effect, which arises from radiation pressure, accelerates the spin rate of asymmetric asteroids, which can eventually shear themselves apart. This pressure is maintained and enhanced around dying stars because the outward push of an asteroid due to stellar mass loss is insignificant compared to the resulting stellar luminosity increase. Consequently, giant star radiation will destroy nearly all bodies with radii in the range 100 m-10 km that survive their parent star's main-sequence lifetime within a distance of about 7 au; smaller bodies are spun apart to their strongest, competent components. This estimate is conservative and would increase for highly asymmetric shapes or incorporation of the inward drag due to giant star stellar wind. The resulting debris field, which could extend to thousands of au, may be perturbed by remnant planetary systems to reproduce the observed dusty and gaseous discs which accompany polluted white dwarfs.

  8. The Effect of Hormone Replacement Therapy on Dry Eye Syndrome Evaluated with Schirmer Test and Break-Up Time

    Directory of Open Access Journals (Sweden)

    Yanhong Feng

    2015-01-01

    Full Text Available Hormone replacement therapy (HRT for dry eye syndrome (DES is controversial in clinical practice. The goal of this study was to review relevant studies and analyze the pooled data to determine whether HRT is effective for DES. In this study, a literature search of PubMed, Embase, and Cochrane databases up to May 2015 was performed, with the search restricted to English language publications. The studies were screened after reading the abstract and full text. Only studies related to the effect of HRT on DES were included in the meta-analysis. Results of Schirmer tests with and without anesthetics and tear break-up time (BUT values data were extracted and entered into RevMan software to meta-analyze the overall effect of HRT on DES. A total of 43 studies were identified, and 21 of these studies were found to be related to the effect of HRT on DES. Ultimately, 5 studies were included in the final meta-analysis. The pooled results revealed that HRT can affect Schirmer test results without anesthetics but does not affect Schirmer test results with anesthetics and BUT. The results indicate that HRT might improve DES symptoms when measuring basal tear production without anesthesia.

  9. Elastic scattering and reaction mechanisms of the halo nucleus $^{11}$Be around the Coulomb barrier

    CERN Document Server

    Di Pietro, A; Fisichella, M; Borge, M J G; Randisi, G; Milin, M; Figuera, P; Gomez-Camacho, J; Raabe, R; Amorini, F; Fraile, L M; Rizzo, F; Zadro, M; Torresi, D; Wenander, F; Pellegriti, M G; Papa, M; Jeppesen, H; Santonocito, D; Scuderi, V; Acosta, L; Perez-Bernal, F; Tengblad, O; Lattuada, M; Musumarra, A; Scalia, G; Maira Vidal, A; Voulot, D

    2010-01-01

    Collisions induced by $^{9}$Be, $^{10}$Be, $^{11}$Be on a $^{64}$Zn target at the same c. m. energy were studied. For the first time, strong effects of the $^{11}$Be halo structure on elastic-scattering and reaction mechanisms at energies near the Coulomb barrier are evidenced experimentally. The elastic-scattering cross section of the $^{11}$Be halo nucleus shows unusual behavior in the Coulomb-nuclear interference peak angular region. The extracted total-reaction cross section for the $^{11}$Be collision is more than double the ones measured in the collisions induced by $^{9}$Be, $^{10}$Be. It is shown that such a strong enhancement of the total-reaction cross section with $^{11}$Be is due to transfer and breakup processes.

  10. Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Mahir S. [DCTA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, C. P. 72012, Sao Paulo, SP (Brazil); Universidade de Sao Paulo, Instituto de Fisica, C. P. 66318, Sao Paulo, SP (Brazil)

    2017-05-15

    In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB) Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d, p) reaction is predominantly a compound-nucleus one, the Trojan Horse Method assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how these seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory. (orig.)

  11. Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

    Science.gov (United States)

    Hussein, Mahir S.

    2017-05-01

    In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB) Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a ( d, p) reaction is predominantly a compound-nucleus one, the Trojan Horse Method assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how these seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory.

  12. Direct observation and validation of fluorescein tear film break-up patterns by using a dual thermal-fluorescent imaging system.

    Science.gov (United States)

    Su, Tai-Yuan; Chang, Shu-Wen; Yang, Chiao-Ju; Chiang, Huihua Kenny

    2014-08-01

    The fluorescein tear film break-up test is a common tear film stability test for dry eye diagnosis. This test requires applying fluorescein sodium drops to a tear film to observe the tear film break-up. However, this test is limited by using the fluorescein sodium drops, which can induce reflex tearing and reduce the reliability of the diagnosis results. This paper proposes that tear film evaporation accelerates on the fluorescein tear film break-up area (FTBA), resulting in a lower temperature area (LTA) on the tear film. A dual modality system was established to capture the thermal and fluorescent image of fluorescein-stain tear films for 48 participants. Observations showed that the LTA and FTBA were highly correlated in their location (r = 0.82) and size (r = 0.91). This is first study to show that the FTBA and LTA are essentially the same region. This study demonstrated the feasibility of using the noncontact thermograph method to evaluate tear film stability without using a fluorescein sodium drop.

  13. Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow

    Science.gov (United States)

    Bender, Achim; Stephan, Peter; Gambaryan-Roisman, Tatiana

    2017-08-01

    Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

  14. Application of the Trojan Horse Method to study neutron induced reactions: the 17O(n, α14C reaction

    Directory of Open Access Journals (Sweden)

    Gulino M.

    2014-03-01

    Full Text Available The reaction 17O(n, α14C was studied using virtual neutrons coming from the quasi-free deuteron break-up in the three body reaction 17O+d → α+14C+p. This technique, called virtual neutron method, extends the Trojan Horse method to neutron-induced reactions allowing to study the reaction cross section avoiding the suppression effects coming from the penetrability of the centrifugal barrier. For incident neutron energies from thermal up to a few hundred keV, direct experiments have shown the population of two out of three expected excited states at energies 8213 keV and 8282 keV and the influence of the sub-threshold level at 8038 keV. In the present experiment the 18O excited state at E* = 8.125 MeV, missing in the direct measurement, is observed. The angular distributions of the populated resonances have been measured for the first time. The results unambiguously indicate the ability of the method to overcome the centrifugal barrier suppression effect and to pick out the contribution of the bare nuclear interaction.

  15. Anaphylaxis-Like Reactions

    Science.gov (United States)

    ... Home Conditions Anaphylaxis Anaphylaxis-Like Reactions Anaphylaxis-Like Reactions Make an Appointment Refer a Patient Ask a ... exposed to a foreign substance, some people suffer reactions identical to anaphylaxis, but no allergy (IgE antibody) ...

  16. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  17. On Thermonuclear Reaction Rates

    OpenAIRE

    Haubold, H. J.; Mathai, A. M.

    1996-01-01

    Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are als...

  18. Role of Barrier Modification and Nuclear Structure Effects in Sub-Barrier Fusion Dynamics of Various Heavy Ion Fusion Reactions

    Science.gov (United States)

    Gautam, Manjeet Singh; Vinod, K.; Kumar, Hitender

    2017-10-01

    The role of barrier modifications and the relevant nuclear structure effects in the fusion of the {}_8{}^{16}O+{}_{62}{}^{144,148,150,152,154}Sm and {}_3{}^{6,7}Li+{}_{62}{}^{152}Sm systems is analyzed within the context of the energy-dependent Woods-Saxon potential model (EDWSP model) and the coupled channel model. For the {}_8{}^{16}O+{}_{62}{}^{144,148,150,152,154}Sm reactions, where the colliding pairs are stable against breakup, the collective excitations and/or static deformations are sufficient to account for the observed fusion enhancement. In contrast, the model calculations overpredict the complete fusion data at above - barrier energies for the {}_3{}^{6,7}Li+{}_{62}{}^{152}Sm systems, where the importance of projectile breakup effects has been pointed out. Due to the low threshold of the alpha-breakup channel, the weakly bound projectiles ({}_3{}^{6,7}Li) break up into charged fragments before reaching the fusion barrier and consequently the complete fusion cross section is suppressed by 28% (25%) in the {}_3{}^6Li+{}_{62}{}^{152}Sm({}_3{}^7Li+{}_{62}{}^{152}Sm) reaction with respect to predictions of coupled channel calculations. However, the EDWSP model based calculations can minimize the suppression factor by as much as of 13% (8%) in the {}_3{}^6Li+{}_{62}{}^{152}Sm({}_3{}^7Li+{}_{62}{}^{152}Sm) reaction with reference to the predictions made by the coupled channel calculations. Therefore, the complete fusion data of the {}_3{}^6Li+{}_{62}{}^{152}Sm({}_3{}^7Li+{}_{62}{}^{152}Sm) reaction at above - barrier energies is reduced by 15% (17%) with respect to the expectations of the EDWSP model. The extracted suppression factors for the studied reactions are due to the modifications of the barrier profile as a consequence of the energy - dependence in nucleus-nucleus potential, and thus greater barrier modifications occur for more weakly bound system, which in turn, confirms the breakup of projectile in the incoming channel.

  19. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  20. Research on the fundamental process of thermal-hydraulic behaviors in severe accident. Breakup and cooling of molten material jets. JAERI's nuclear research promotion program, H10-027-2. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Ken-ichiro; Iguchi, Kentarou [Hokkaido Univ., Graduate School of Engineering, Sapporo, Hokkaido (Japan)

    2002-03-01

    Core melt accidents could lead to the pouring of molten core materials into a body of water accumulating in the reactor lower head in the form of jets with a few centimeters up to a few tens of centimeters. If molten core jets penetrate the body of water without breakup. A poor coolability of the molten core bed would occur, which means the difficulty of maintaining the molten core bed in the reactor vessel. Hence, the breakup mechanism of molten core jets had to be well understood for the evaluation of the coolability of molten core bed. The objective of the present experimental study is to confirm that, even in molten material jets, the breakup of jet originating in the coolant entrained within a molten material jet due to 'the organized motion' between the coolant and the jet, which has been recognized in the field of fluid mechanics, is caused. The first series of experiment was conducted to observe this type of breakup by using molten tin jets up to 25 mm in diameter. Molten tin jet was expected to easily cause this kind of breakup of jet because of a low kinematic viscosity, which means a easy transformation of jet due to the organized motion for the coolant to entrain. The second series of experiment was conducted by using molten copper jet of 25 mm in diameter, of which kinematic viscosity is about same as that of molten UO{sub 2}. The breakup of jet due to the entrainment of the coolant was observed up to high ambient Weber numbers, which cover the atomization regime. The mechanism of the breakup observed in the present study is able to reasonably explain the apparent difference between the breakup lengths of 150 kg-scale corium jets and the breakup lengths of about 8 kg-scale lead-bismuth alloy jets. The breakup by the mechanism reported here also assures a high coolability of molten jets because of an efficient entrainment of coolant within the jet. (author)

  1. Mesozoic break-up of SW Gondwana: implications for regional hydrocarbon potential of the southern South Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, D. [University of Cambridge (United Kingdom). CASP; University of Abderdeen (United Kingdom). Kings College; Gomez-Perez, I. [University of Cambridge (United Kingdom). CASP; Franzese, J. [Centro de Investigaciones Geologicas, La Plata (AR)] (and others)

    2003-04-01

    This work provides new palinspastic palaeofacies reconstructions of SW Gondwana incorporating rotation of a Falkland/Malvinas microplate. We discuss the implications of this for the tectonic evolution of the southern South Atlantic and hence for the regional hydrocarbon potential. Existing Gondwana reconstructions display good fits of major continents but poorly constrained fits of microcontinents. In most continental reconstructions, the Falkland/Malvinas Plateau was assumed to be a rigid fragment of pre-Permian South American crust. However, it has been suggested, on the basis of palaeomagnetic data, that the Falkland/Malvinas Islands were rotated by {approx} 180{sup o} after 190 Ma. This rotation hypothesis has been successfully tested on the basis of Devonian stratigraphy and palaeontology, Permian stratigraphy and sedimentology and Late Palaeozoic and Early Mesozoic structure, making it unlikely that the plateau behaved as a rigid structure during breakup. We have explored the consequences of accepting this hypothesis for the tectonic evolution of SW Gondwana by compiling new palaeogeographic maps for the Permian-Cretaceous of the southern Atlantic area. To achieve a realistic close fit, we have devised a pre-rift proxy for the ocean-continent boundary for the South Atlantic. In order to produce the best fit, it is necessary to subdivide South America into four plates. The consequences of this are far-reaching. Our work suggests that although sedimentary basins were initiated at different times, three major tectonic phases can be recognised; in regional terms these can be thought of as pre-, syn- and post-rift. During the pre-rift time (until the Late Triassic), the area was dominated by compressional tectonism and formed part of the Gondwana foreland. The Falkland/Malvinas Islands lay cast of Africa, the Falkland/Malvinas Plateau was {approx} 33% shorter and Patagonia was displaced east with respect to the rest of South America, in part along the line of the

  2. Randomized controlled pilot of an intervention to reduce and break-up overweight/obese adults' overall sitting-time.

    Science.gov (United States)

    Júdice, Pedro B; Hamilton, Marc T; Sardinha, Luís B; Silva, Analiza M

    2015-11-02

    Too much prolonged sitting is a prevalent health risk among adults. Interventions have focused mainly on the workplace, with limited attention to non-work settings. The effectiveness of a short-term intervention to reduce and break-up sitting-time in overweight/obese adults was examined. This pilot study sought to determine the feasibility of interrupting sitting to stand/ambulate objectively with ActivPAL devices which provide a valid measurement of sit/stand transitions. This is a cross-over randomized controlled pilot that included 10 participants (aged 37-65 years) and although a small and short-term intervention (1-week intervention; no washout) further informs on the feasibility of interventions on a larger scale. At the workplace, screen-delivered hourly alerts prompted participants to break-up sitting-time through adopting walking behaviors (approximately 30-60 minutes day(-1)). During transportation/home/leisure-time individual goals for steps day(-1) were set and sitting-reduction strategies (including behavioral self-monitoring) were delivered through daily text messages. Change in inclinometer-derived sitting-time is the main outcome. Standing, stepping, number of sit/stand transitions and participant satisfaction were also examined. For the intervention compared to the control-week (mean difference (95 % confidence interval); p value), participants had less sitting-time (1.85 hours (0.96-2.75); p = 0.001), more standing (0.77 hours (0.06-1.48); p = 0.036), and more stepping (1.09 hours (0.79- 1.38); p change in the total number of sit/stand transitions (3.28 (-2.33-8.89); p = 0.218) despite successfully reducing sitting-time and increasing time spent standing and walking. Sitting-time in overweight/obese adults can be reduced following a brief multi-component intervention based on prompts, telephone support, goal setting and behavioral self-monitoring. However, the results from this pilot study provide new insight that when overweight

  3. The Relationship Between Tear Ferning Patterns and Non-invasive Tear Break-up Time in Normal Asian Population.

    Science.gov (United States)

    Sharanjeet-Kaur; Ho, Chien Yee; Mutalib, Haliza Abdul; Ghazali, Ahmad Rohi

    2016-01-01

    To investigate the relationship between tear ferning patterns (TFP) and non-invasive tear break-up time (NIBUT) in normal Asian subjects. One hundred and forty-five adults with no ocular surface disorders were recruited. TFP and NIBUT were determined. Tears were collected using a capillary tube and allowed to air dry at room temperature for 10min. TFP was later observed using a light microscope and classified according to Rolando's classification. Measurement for NIBUT was obtained using a Tearscope with the slit lamp magnification. It was found that there is no significant difference between gender in TFP (Z=-1.77, P>.05) and NIBUT (Z=-1.475, P>.05). There is also no significant difference between Malay, Chinese, Indian, and other races in TFP, (H(3)=4.85, P>.05) and NIBUT (H(3)=2.18, P>.05). However, there is a significant difference between age groups of 20-29, 30-39, 40-49,and 50-60 years old in both TFP (H(3)=28.25, P<.01) and NIBUT (H(3)=36.50, P<.001). Spearman's correlation showed there was a significant relationship between TFP and NIBUT (r=-0.55, P<.001), age and NIBUT (r=-0.50, P<.001), age and TFP (r=0.41, P<.001), McMonnies score and NIBUT (r=-0.40, P<.001), McMonnies score and TFP (r=0.31, P<.001), as well as age and McMonnies score (r=0.52, P<.001). TFP and NIBUT was age dependent but not gender and race dependent. Older subjects had higher grade of TFP and McMonnies questionnaire score but lower NIBUT value. TFP and NIBUT can be used to assess the tear film quality. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  4. Determination of tear break-up time reference values and ocular tolerance of tetracaine hydrochloride eyedops in healthy horses.

    Science.gov (United States)

    Monclin, S J; Farnir, F; Grauwels, M

    2011-01-01

    Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break-up time (TBUT) is a useful test allowing an assessment of the quality of the precorneal tear film. Only one TBUT value has been reported in horses with no information on the technique used. To provide a method for performing the TBUT in horses and to report any side effects of a single application of THCl in clinically normal horses, particularly on the stability of the tear film. In Study 1, one drop of 0.5 or 1% THCl was applied to one eye of 20 horses divided in 2 groups. Treated eyes were assessed for the development of side effects 2.5 and 5 min after treatment. In Study 2, the TBUT was measured in both eyes of 2 groups of 10 horses, before and 2.5 and 5 min after, instillation of one drop of either 0.5 or 1% THCl. No animals developed any ocular side effect after instillation. Basal TBUT was 8.3±1.3 s. TBUT decreased from baseline 5 and 2.5 min after application of one drop of 0.5% THCl and one drop of 1% THCl, respectively. A technique to measure the TBUT in healthy horses is described and normal range values that could be used as a reference were obtained. THCl is well tolerated in horses but lowers the TBUT. © 2010 EVJ Ltd.

  5. Simulation of dC and dCH{sub 2} reactions from 300 MeV up to 500 MeV of deuteron energy

    Energy Technology Data Exchange (ETDEWEB)

    Janek, M., E-mail: janek@fyzika.uniza.sk [Physics Dept., University of Zilina, 01026 Zilina (Slovakia); Trpisova, B. [Physics Dept., University of Zilina, 01026 Zilina (Slovakia); Ladygin, V.P.; Piyadin, S.M. [Joint Institute for Nuclear Researches, LHEP, 141980 Dubna (Russian Federation)

    2013-12-15

    GEANT4 simulations of dC and dCH{sub 2} reactions at 300 MeV, 400 MeV and 500 MeV of deuteron energy for different detector configurations are presented. Two threads made from polyethylene and carbon are used as targets. The goal of the simulations is to find a method by means of which the signal from the dp non-mesonic breakup reaction can be separated from the background that mainly comes from the carbon content of the targets. The obtained results will be used in the experimental spin program that will be realized in Nuclotron in Dubna.

  6. Production of Energetic Light Fragments in Spallation Reactions

    Directory of Open Access Journals (Sweden)

    Mashnik Stepan G.

    2014-03-01

    Full Text Available Different reaction mechanisms contribute to the production of light fragments (LF from nuclear reactions. Available models cannot accurately predict emission of LF from arbitrary reactions. However, the emission of LF is important formany applications, such as cosmic-ray-induced single event upsets, radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The cascade-exciton model (CEM and the Los Alamos version of the quark-gluon string model (LAQGSM, as implemented in the CEM03.03 and LAQGSM03.03 event generators used in the Los Alamos Monte Carlo transport code MCNP6, describe quite well the spectra of fragments with sizes up to 4He across a broad range of target masses and incident energies. However, they do not predict high-energy tails for LF heavier than 4He. The standard versions of CEM and LAQGSM do not account for preequilibrium emission of LF larger than 4He. The aim of our work is to extend the preequilibrium model to include such processes. We do this by including the emission of fragments heavier than 4He at the preequilibrium stage, and using an improved version of the Fermi Break-up model, providing improved agreement with various experimental data.

  7. Mexican data indicating ca.700 Ma breakup of Rodinia and ca.550 Ma separation of Avalonia: analogous to events in western Laurentia

    Science.gov (United States)

    Keppie, J. D.; Nance, R. D.; Miller, B. V.; Dostal, J.

    2004-05-01

    The supercontinent, Rodinia, appears to have been amalgamated by ca.1 Ga, however, its breakup in Laurentia appears to have occurred in two stages. Current hypotheses suggest that East Gondwana or Siberia separated from western Laurentia at ca.700 Ma followed by separation of (?) South China at ca.550 Ma producing two superposed passive margin sequences. Although prevailing wisdom suggests that the birth of Iapetus between North and South America occurred at ca.550 Ma, a similar 2-stage process is evident in both eastern Laurentia and Mexico. At ca.1 Ga, Mexico appears to have been located in or close to the North-South America suture and so provides crucial data. Geochronological data indicate that cooling following ca.1 Ga granulite facies orogenesis in Mexico followed two different paths. In southern Mexico the rocks initially cooled through ca.450° C at a rate of ca.8° C/my between 978 Ma and 945 Ma related to flat-slab subduction, followed by a cooling rate of ca.2° C/my through ca.150° C. In northern Mexico the rocks cooled at a steady rate of ca.1.8° C/my through ca.300° C and are cut by plume-related mafic dykes. Extrapolating these cooling paths to the surface indicates that southern Mexico reached the surface between 710 and 760 Ma, whereas northern Mexico reached the surface by 550 Ma. This may be partly explained by different depths of exhumation: 30 versus 37 km for southern and northern Mexico, respectively. On the other hand, the oldest rocks resting on the ca.1 Ga basement are Tremadocian (ca.490-480 Ma) in southern Mexico and Middle Silurian (ca.430-425 Ma) in northern Mexico. Thus it would appear that Mexico records two breakup stages: (1) at ca.700 Ma possibly related to the breakup of Rodinia; (2) at ca.550 Ma possibly related to the transcurrent separation of Avalonia followed by thermal equilibration at ca.500 Ma leading to subsidence and development of a passive margin. These data suggest that the breakup of Rodinia occurred at ca.700

  8. Fragmentation of the "bag-breakup" type as a mechanism of the generation of sea spray at strong and hurricane winds

    Science.gov (United States)

    Troitskaya, Yu. I.; Ermakova, O. S.; Kandaurov, A. A.; Kozlov, D. S.; Sergeev, D. A.; Zilitinkevich, S. S.

    2017-11-01

    Experiments on generation mechanisms of sea water spray under hurricane wind were performed using shadow illumination high-speed video recording from several camera positions. Classification of fragmentation mechanism leading to generation of spray was conducted. Statistics of the events causing generation of spray was studied. A phenomenological model was developed based on the methods of statistical physics to describe the "bag-breakup" generation mechanism. The function of spray generation was conducted on this basis, which describes well the experimental data obtained under hurricane winds in the natural and laboratory conditions.

  9. Does the association between broken partnership and first time myocardial infarction vary with time after break-up?

    Science.gov (United States)

    Kriegbaum, Margit; Christensen, Ulla; Andersen, Per Kragh; Osler, Merete; Lund, Rikke

    2013-12-01

    Marriage is associated with lower risk of coronary heart disease, but it is unknown if the association depends on time since break-up with a partner. In this study we included both married and unmarried couples to study if the association between broken partnership (BP) and first time incident myocardial infarction (MI) changes with time since BP. Register study of the entire Danish population: the population was restricted to those aged 30 to 65 years with follow-up for incident MI between 1985 and 2006 with an annual record on each individual; in total 43 million records. The register data were used to identify MI events. Poisson regression was used to study associations between time since BP and MI adjusted for socio-demographic confounders and hospital admissions. Analyses were stratified by sex. Compared with unexposed (no BP), the incidence rate ratio (IRR) of MI in men with BP in the same year was 0.97 [95% confidence interval (CI) 0.90-1.05], year before BP was 1.25 (95% CI 1.17-1.34), 2-3 years after BP was 1.12 (95% CI 1.06-1.18), 4-8 years after BP was 1.09 (95% CI 1.05-1.14) and 9+ years since BP was 1.09 (95% CI 1.05-1.12). In women, the IRR same year as BP was 1.45 (95% CI 1.26-1.66), the year after BP was 1.30 (95% CI 1.14-1.50), 2-3 years after BP was 1.26 (95% CI 1.13-1.39), 4-8 years after BP was 1.17 (95% CI 1.08-1.26) and 9+ years since BP was 1.24 (95% CI 1.17-1.32). We found both a short-term elevated risk of first time MI following BP and a weaker long-term elevated risk, in both men and women.

  10. A new modified fluorescein strip: Its repeatability and usefulness in tear film break-up time analysis.

    Science.gov (United States)

    Pult, H; Riede-Pult, B H

    2012-02-01

    To (i) analyze the repeatability of fluorescein instillation from a modified fluorescein strip (MFS) compared to a standard fluorescein strip (FS), and to (ii) observe its usefulness in the measurement of the fluorescein break-up time (FBUT) in comparison to the Tearscope (NIBUT). In-vitro: Intra- and inter-observer repeatability in fluorescein instillation from the MFS and FS was evaluated by fluorescence analysis (n=10, each). In-vivo: BUT of the right eye of 20 randomly selected subjects (mean age 43.3±11.5, range=21-60 years, 8 males, 12 females) was measured by use of the Tearscope and MFS. Subjects were grouped by the Ocular Surface Disease Index (OSDI) score into 8 OSDI+ and 12 OSDI- by a cut-off value of 15. In-vitro: Intra-observer 95% limit of agreement (LoA) of the MFS was similar to the FS LoA in observer 1 (O1), but better than the FS LoA in observer (O2) (MFS: O1: LoA=±1.98 mW; p=0.179; O2: ±2.71; 0.442; FS: O1: ±1.71; 0.246; O2: ±4.11; 0.512). Inter-observer LoA in fluorescence was better in MFS (±1.42; 0.111) than in FS (±3.71; 0.003). In-vivo: MFS-BUT was significantly shorter than the NIBUT (p=0.002), but significantly correlated (r=0.864, p<0.001). NIBUT and MFS-BUT were significant discriminators (p<0.001) of OSDI±(0.948/8s and 0.938/5s [AUC/cut-off value]; NIBUT and MFS-BUT, respectively). The MFS was better in the repeatability of fluorescein instillation than the FS. NIBUT and MFS-BUT were good discriminators of dry eye symptoms, but differ in their cut-off values. Copyright © 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  11. Magmatism during Gondwana breakup

    DEFF Research Database (Denmark)

    van der Meer, Quinten; Scott, J.M.; Waight, Tod Earle

    2013-01-01

    Newly determined mid-late Cretaceous 40Ar/39Ar ages on megacrystic kaersutite from lamprophyre dikes in central and north Westland (New Zealand) are presented. These ages (88 Ma, 86 Ma and 68 Ma) indicate that the intrusion of mafic dikes was not necessarily restricted to the previously establish...

  12. [Adverse reactions to insulin].

    Science.gov (United States)

    Liñana, J J; Montoro, F J; Hernández, M D; Basomba, A

    1997-07-01

    The prevalence of allergic reactions to insuline has decreased during the last few years. Probably this is due to the use of the newly-developed recombinant human insuline. At present, adverse reactions to insuline occur in 5-10% of patients on therapy with insuline. Adverse reactions may be local (more frequent) or systemic (rare). Insuline resistance consists in a different type of immunological reaction. Diagnosis of allergy to insuline is based on clinical history and cutaneous and serological tests. Treatment depends upon the severity of the reaction. When insuline is indispensable despite a previous allergic reaction, a desensitization protocol may be implemented.

  13. Cross section measurement for the 10B(n ,t 2 α ) three-body reaction at 4.0, 4.5, and 5.0 MeV. I. Prediction of the experimental spectrum

    Science.gov (United States)

    Wang, Zhimin; Bai, Huaiyong; Zhang, Luyu; Jiang, Haoyu; Lu, Yi; Chen, Jinxiang; Zhang, Guohui; Gledenov, Yu. M.; Sedysheva, M. V.; Khuukhenkhuu, G.

    2017-10-01

    Cross sections of the 10B(n ,t 2 α ) three-body reaction were measured at En=4.0 ,4.5 , and 5.0 MeV using a twin gridded ionization chamber and a thin-film 10B sample. The present paper is the first part of the work. The experimental spectrum of the 10B(n ,t 2 α ) reaction measured by the gridded ionization chamber (GIC) was predicted. The 10B(n ,t 2 α ) reaction can proceed in three ways, which are referred to as 7Li**,8Be , and breakup channels. The energies and directional angles of the three particles in the final states for the 7Li**,8Be , and breakup channels were calculated, respectively. Based on these results, the one-dimensional and two-dimensional spectra were calculated through integration. Three kinds of interference reactions were taken into account, which were the 10B(n,α ) 7Li reaction, the H(n ,n )p reaction, and the (n ,α) reactions from the working gas of the GIC. Two effects were considered in the prediction of the experimental spectrum, which were the energy loss of the products in the sample and the wall effect of the sample position well. The predicted spectra play an important role in the guidance of the implementation of the experiment and the processing of the experimental data.

  14. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng [Irvine, CA; Sui, Guodong [Los Angeles, CA; Elizarov, Arkadij [Valley Village, CA; Kolb, Hartmuth C [Playa del Rey, CA; Huang, Jiang [San Jose, CA; Heath, James R [South Pasadena, CA; Phelps, Michael E [Los Angeles, CA; Quake, Stephen R [Stanford, CA; Tseng, Hsian-rong [Los Angeles, CA; Wyatt, Paul [Tipperary, IE; Daridon, Antoine [Mont-Sur-Rolle, CH

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  15. Allergic reactions (image)

    Science.gov (United States)

    Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as ... mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are ...

  16. Cosmetic tattoo pigment reaction

    National Research Council Canada - National Science Library

    Greywal, Tanya; Cohen, Philip R

    2016-01-01

    BackgroundCutaneous reactions to tattoos are most commonly granulomatous or lichenoid.PurposeWe describe a woman who developed a lymphocytic reaction following a cosmetic tattoo procedure with black dye...

  17. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  18. Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica

    Directory of Open Access Journals (Sweden)

    Catherine Riaux-Gobin

    2011-01-01

    Full Text Available The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cylindrus did develop. Pelagic species were becoming more abundant offshore, replacing the typical sympagic (ice-associated taxa. Archaeomonad cysts, usually associated with sea ice, were recorded in the surface waters nearshore. Rough weather restricted the data set, but we were able to confirm that some microalgae may be reliable sea-ice indicators and that seeding by sea ice only concerns a few taxa in this coastal area of East Antarctica.

  19. Reaction Time (Polish language)

    OpenAIRE

    Iermakov, Sergii

    2014-01-01

    Reaction time is the interval time between the presentation of a stimulus and the initiation of the muscular response to that stimulus.If there is only one possible response (simple reaction time) it will only take a short time to react. If there are several possible responses (choice reaction time) then it will take longer to determine which response to carry out.

  20. Laser enhanced chemical reactions

    Science.gov (United States)

    Included is the discussion of infrared diode lasers used to study time dependent dynamic events. Also, hot atom excitation of vibrational states of polyatomic molecules, bimolecular quenching and reactions of O(sup 1)D, bimolecular reaction studies of the OH + CO yields H + CO2 system, and the chemical dynamics of the reaction between chlorine atoms and deuterated cyclohexane are covered briefly.

  1. (MIRC) reaction w

    Indian Academy of Sciences (India)

    Sudesh Kumari

    as eco-friendly reaction media in catalyst free organic synthesis.7 Ethylene glycol has promising physical ... these properties it is used as a promising green media in many catalysed/ uncatalysed organic reactions ..... Ruijter E, Scheffelaar R and Orru R V A 2011 Multi- component Reaction Design in the Quest for Molecular ...

  2. Energetic efficiency of mass transfer accompanied by chemical reactions in liquid-liquid systems

    Directory of Open Access Journals (Sweden)

    Jasińska Magdalena

    2017-09-01

    Full Text Available Energetic efficiency depicting the fraction of energy dissipation rate used to perform processes of drop breakup and mass transfer in two-phase, liquid-liquid systems is considered. Results of experiments carried out earlier in two types of high-shear mixers: an in-line rotor-stator mixer and a batch rotor-stator mixer, have been applied to identify and compare the efficiency of drop breakage and mass transfer in both types of mixers. The applied method is based on experimental determination of both: the product distribution of chemical test reactions and the drop size distributions. Experimental data are interpreted using a multifractal model of turbulence for drop breakage and the model by Favelukis and Lavrenteva for mass transfer. Results show that the energetic efficiency of the in-line mixer is higher than that of the batch mixer; two stator geometries were considered in the case of the batch mixer and the energetic efficiency of the device equipped with a standard emulsor screen (SES was higher than the efficiency of the mixer equipped with a general purpose disintegrating head (GPDH for drop breakup but smaller for mass transfer.

  3. Neutron spectra from beam-target reactions in dense Z-pinches

    Energy Technology Data Exchange (ETDEWEB)

    Appelbe, B., E-mail: b.appelbe07@imperial.ac.uk; Chittenden, J. [Centre for Inertial Fusion Studies, The Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom)

    2015-10-15

    The energy spectrum of neutrons emitted by a range of deuterium and deuterium-tritium Z-pinch devices is investigated computationally using a hybrid kinetic-MHD model. 3D MHD simulations are used to model the implosion, stagnation, and break-up of dense plasma focus devices at currents of 70 kA, 500 kA, and 2 MA and also a 15 MA gas puff. Instabilities in the MHD simulations generate large electric and magnetic fields, which accelerate ions during the stagnation and break-up phases. A kinetic model is used to calculate the trajectories of these ions and the neutron spectra produced due to the interaction of these ions with the background plasma. It is found that these beam-target neutron spectra are sensitive to the electric and magnetic fields at stagnation resulting in significant differences in the spectra emitted by each device. Most notably, magnetization of the accelerated ions causes the beam-target spectra to be isotropic for the gas puff simulations. It is also shown that beam-target spectra can have a peak intensity located at a lower energy than the peak intensity of a thermonuclear spectrum. A number of other differences in the shapes of beam-target and thermonuclear spectra are also observed for each device. Finally, significant differences between the shapes of beam-target DD and DT neutron spectra, due to differences in the reaction cross-sections, are illustrated.

  4. Mirror denudation pattern on both sides of the Central Atlantic - a trace of the Pangea break-up?

    Science.gov (United States)

    Ruiz, G.; Saddiqi, O.; Sebti, S.; Negro, F.; Stuart, F.; Foeken, J.; Frizon de Lamotte, D.; Kramers, J.

    2009-04-01

    -Atlas. Second, they are being affected "now" but no level with such record is yet exposed. Thermal modelling was performed to decipher between the 2 scenarios using our new thermochronological and available geological constraints. Models suggest that the first scenario is most likely with a clear Triassic to Late Jurassic phase of heating until ~100-90°C that was followed by a phase of cooling until the Middle Cretaceous. These results suggest that the Meseta was buried by a 2-3 kilometres thick sedimentary pile until ~180 Ma and as a result that the concept of a topographic high limiting the Tethysian from the Atlantic has to be reconsidered. Further, denudation patterns from the mirror image of the Atlas system on the other side of the Atlantic ocean are almost identical (Grist and Zentilli, 2003) suggesting that the patterns we constrained for the Triassic until Middle Cretaceous in SW Morocco have to be related to the break-up of the Pangea and oceanization in the Central Atlantic from ~180 Ma.

  5. Reactions with fast radioactive beams of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  6. Hypersensitivity reactions to heparins.

    Science.gov (United States)

    Gonzalez-Delgado, Purificación; Fernandez, Javier

    2016-08-01

    This article provides an update on hypersensitivity reactions to heparins and novel oral anticoagulants, with special emphasis on diagnostic methods and management of patients. Although heparins are drugs widely used, hypersensitivity reactions are uncommon. Cutaneous delayed hypersensitivity reactions after subcutaneous administration affects up to 7.5% of patients. Heparin-induced thrombocytopenia is another unusual but severe condition in which early recognition is crucial. Immediate hypersensitivity reactions to heparins have been also reported, but with the novel oral anticoagulants are much more uncommon, although reports of exanthemas have been notified.Skin tests and subcutaneous provocation test are useful tools in the diagnosis of hypersensitivity reactions, except in heparin-induced thrombocytopenia in which biopsy of lesional skin and in-vitro tests are the modalities of choice to confirm the diagnosis.Management of hypersensitivity reactions includes finding an alternative depending on the type of reaction. Fondaparinux and novel oral anticoagulants may be safe alternatives. Delayed skin lesions after subcutaneous heparin are the most common type of hypersensitivity reactions, followed by life-threatening heparin-induced thrombocytopenia. Immediate reactions are uncommon. Allergologic studies may be useful to find an alternative option in patients with skin lesions in which heparin-induced thrombocytopenia has been previously excluded, as well as in heparin immediate reactions.

  7. Incomplete fusion analysis of the 7Li-induced reaction on 93Nb within 3-6.5 MeV/nucleon

    Science.gov (United States)

    Kumar, Deepak; Maiti, Moumita

    2017-10-01

    Background: It is understood from the recent experimental studies that prompt/resonant breakup, and transfer followed by breakup in the weakly bound Li,76-induced reactions play a significant role in the complete-incomplete fusion (CF-ICF), suppression/enhancement in the fusion cross section around the Coulomb barrier. Purpose: Investigation of ICF over CF by measuring cross sections of the populated residues, produced via different channels in the 7Li-induced reaction on a natNb target within the 3-6.5 MeV/nucleon energy region. Method: The 7Li beam was allowed to hit the self-supporting 93Nb targets, backed by the aluminium (Al) foil alternately, within 3-6.5 MeV/nucleon energy. Populated residues were identified by offline γ -ray spectrometry. Measured excitation functions of different channels were compared with different equilibrium and pre-equilibrium models. Result: The enhancement in cross sections in the proton (˜20 -30 MeV) and α -emitting channels, which may be ascribed to ICF, was observed in the measured energy range when compared to the Hauser-Feshbach and exciton model calculations using empire, which satisfactorily reproduces the neutron channels, compared to the Weisskopf-Ewing model and hybrid Monte Carlo calculations. The increment of the incomplete fusion fraction was observed with rising projectile energy. Conclusion: Contrary to the alice14, experimental results are well reproduced by the empire throughout the measured energy range. The signature of ICF over CF indicates that the breakup/transfer processes are involved in the weakly bound 7Li-induced reaction on 93Nb slightly above the Coulomb barrier.

  8. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.

    2005-01-01

    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl

  9. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  10. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  11. Joint Parental Authority : A comparative legal study on the continuation of joint parental authority after divorce and the breakup of a relationship in Dutch and Danish law and the CEFL principles

    NARCIS (Netherlands)

    Jeppesen, C.G.|info:eu-repo/dai/nl/311462952

    2008-01-01

    This book provides a comparative legal study on the continuation of joint parental authority after divorce and the breakup of a relationship in Dutch and Danish law. In addition, the Principles regarding Parental Responsibilities which have been drafted by the Commission on European Family Law are

  12. SPH/N-Body simulations of small (D = 10km) asteroidal breakups and improved parametric relations for Monte-Carlo collisional models

    Science.gov (United States)

    Ševeček, P.; Brož, M.; Nesvorný, D.; Enke, B.; Durda, D.; Walsh, K.; Richardson, D. C.

    2017-11-01

    We report on our study of asteroidal breakups, i.e. fragmentations of targets, subsequent gravitational reaccumulation and formation of small asteroid families. We focused on parent bodies with diameters Dpb = 10km . Simulations were performed with a smoothed-particle hydrodynamics (SPH) code combined with an efficient N-body integrator. We assumed various projectile sizes, impact velocities and impact angles (125 runs in total). Resulting size-frequency distributions are significantly different from scaled-down simulations with Dpb = 100km targets (Durda et al., 2007). We derive new parametric relations describing fragment distributions, suitable for Monte-Carlo collisional models. We also characterize velocity fields and angular distributions of fragments, which can be used as initial conditions for N-body simulations of small asteroid families. Finally, we discuss a number of uncertainties related to SPH simulations.

  13. Break-up of two-dimensional MnO2 nanosheets promotes ultrasensitive pH-triggered theranostics of cancer.

    Science.gov (United States)

    Chen, Yu; Ye, Delai; Wu, Meiying; Chen, Hangrong; Zhang, Linlin; Shi, Jianlin; Wang, Lianzhou

    2014-11-05

    Chemically exfoliated two-dimensional MnO2 nanosheets are successfully modified with amino-polyethylene glycol as a theranostic platform for ultrasensitive stimuli-responsive theranostics of cancer. The highly dispersed MnO2 nanosheets exhibit a unique break-up in the mildly acidic microenvironment of tumor tissues, which could substantially enhance their in vitro and in vivo performances in T1 -weighted magnetic resonance imaging. Such a pH-triggered breaking-up behavior could further promote the fast release of loaded anticancer drugs for concurrent pH-responsive drug release and circumvent the multidrug resistance of cancer cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A Unified Model Considering Effects of Droplet Break-Up and Air Entrainment at the Initial Stage of Fuel Spray Penetration

    Directory of Open Access Journals (Sweden)

    S. Jafarmadar

    2014-01-01

    Full Text Available This paper proposes a new unified single model that considers droplet break-up and air entrainment impact on three flow regimes (namely, Stokes, Allen, and Newton in the initial stage of fuel spray penetration. Homotopy perturbation method was used to obtain semianalytical solutions of unified single model on diesel fuel’s spray penetration when the influence of air entrainment is small (up to 0.1-0.2 ms after the start of injection. It is demonstrated that the applied analytical method is very straightforward in comparison with existing techniques. Furthermore, it is decidedly effectual in terms of accuracy and rapid convergence. The formulation of the problem is presented in the text as well as the analytical and numerical procedures.

  15. Reactions to Attitudinal Deviancy.

    Science.gov (United States)

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  16. ORGANIC REACTION MECHANISM CONTROVERSY ...

    African Journals Online (AJOL)

    Preferred Customer

    Chemists, educators and students are entitled to their mental constructs about reaction mechanism in the classroom. What pedagogical implications have these knowledge claims for teaching and learning reaction mechanisms in organic chemistry? This is the main interest of the paper. Thus three questions were critically ...

  17. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  18. Applications of Reaction Rate

    Science.gov (United States)

    Cunningham, Kevin

    2007-01-01

    This article presents an assignment in which students are to research and report on a chemical reaction whose increased or decreased rate is of practical importance. Specifically, students are asked to represent the reaction they have chosen with an acceptable chemical equation, identify a factor that influences its rate and explain how and why it…

  19. Reaction cross sections and elastic scattering energy dependence around the Coulomb barrier for the {sup 7}Be+{sup 27}Al system

    Energy Technology Data Exchange (ETDEWEB)

    Morcelle, Viviane; Gomes, P.R.S.; Lubian, J.; Mendes Junior, D.R. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Camargo, O.; Faria, P.N. de; Gasquez, L.; Morais, M.C.; Condori, R.P.; Pires, K.C.C.; Scarduelli, V. [Universidade de Sao Paulo (USP), SP (Brazil); Barioni, A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Zamora, J.C. [Technische Universitaet Darmstadt (Germany); Aguilera, E.; Martinez-Quiroz, E. [Instituto Nacional de Investigaciones Nucleares (Mexico); Kolata, J.; Jiang, H. [University of Notre Dame, IN (United States); Bechetti, F.D.; Lamm, L.O. [Michigan University, MI (United States); Lizcano, D. [Universidad Autonoma del Estado de Mexico (Mexico)

    2012-07-01

    Full text: Elastic scattering measurements were performed at energies around the Coulomb barrier at the Tandem Accelerators of the Sao Paulo (USP - Brazil ) and Notre Dame (UND - USA) Universities. The {sup 7}Be is a radioactive nucleus and has been produced by the reaction {sup 6}He({sup 6}Li,{sup 9}Be) and impinged on {sup 27}Al and {sup 197}Au secondary targets using a double superconducting systems RIBRAS ( USP ) and Twinsol (UND). The elastic scattering angular distributions were analyzed through the optical model calculations, using the Woods- Saxon form factors [1] and the Sao Paulo potential [2] to fit the experimental data. The total reaction cross sections were also derived and compared with others presented at the literature for other systems. In addition, a study of the nuclear potential energy dependence has been carried out in this work in the dispersion relation context. Due to the fact that {sup 7}Be has a small breakup threshold energy, the results can provide significant information of the influence of the breakup channel on the reactions involving this projectile. For this purpose, {chi}{sup 2}- data analysis with different kind of potentials were performed to identify the energy dependence of the real (V) and imaginary (W) parts of the potential. [1] L.C. Chamon et al., Phys. Rev. C 66, (2002) 014610. [2] R.D. Wood e D.S. Saxon, Phys. Rev. 95 ( 1954) 577. (author)

  20. Formation of ultrathin Ni germanides: solid-phase reaction, morphology and texture

    Science.gov (United States)

    van Stiphout, K.; Geenen, F. A.; De Schutter, B.; Santos, N. M.; Miranda, S. M. C.; Joly, V.; Detavernier, C.; Pereira, L. M. C.; Temst, K.; Vantomme, A.

    2017-11-01

    The solid-phase reaction of ultrathin (⩽10 nm) Ni films with different Ge substrates (single-crystalline (1 0 0), polycrystalline, and amorphous) was studied. As thickness goes down, thin film texture becomes a dominant factor in both the film’s phase formation and morphological evolution. As a consequence, certain metastable microstructures are epitaxially stabilized on crystalline substrates, such as the ɛ-Ni5Ge3 phase or a strained NiGe crystal structure on the single-crystalline substrates. Similarly, the destabilizing effect of axiotaxial texture on the film’s morphology becomes more pronounced as film thicknesses become smaller. These effects are contrasted by the evolution of germanide films on amorphous substrates, on which neither epitaxy nor axiotaxy can form, i.e. none of the (de)stabilizing effects of texture are observed. The crystallization of such amorphous substrates however, drives the film breakup.

  1. Respiratory transfusion reactions

    Directory of Open Access Journals (Sweden)

    Ivica Marić

    2017-11-01

    Full Text Available Respiratory transfusion-related reactions are not very frequent, partly also because recognition and reporting transfusion reactions is still underemphasized. Tis article describes the most important respiratory transfusion reactions, their pathophysiology, clinical picture and treatment strategies. Respiratory transfusion related reactions can be primary or secondary. The most important primary transfusion-related reactions are TRALI - transfusion-related acute lung injury, TACO – transfusion-associated circulatory overload, and TAD - transfusion-associated dyspnea. TRALI is immuneassociated injury of alveolar basal membrane, which becomes highly permeable and causes noncardiogenic pulmonary edema. Treatment of TRALI is mainly supportive with oxygen, fluids (in case of hypotension and in cases of severe acute respiratory failure also mechanic ventilation. TACO is caused by volume overload in predisposed individuals, such as patients with heart failure, the elderly, infants, patients with anemia and patients with positive fluid balance. Clinical picture is that of a typical pulmonary cardiogenic edema, and the therapy is classical: oxygen and diuretics, and in severe cases also non-invasive or invasive mechanical ventilation. TAD is usually a mild reaction of unknown cause and cannot be classified as TACO or TRALI, nor can it be ascribed to patient’s preexisting diseases. Although the transfusion-related reactions are not very common, knowledge about them can prevent serious consequences. On the one hand preventive measures should be sought, and on the other early recognition is beneficial, so that proper treatment can take place.

  2. Complete and incomplete fusion dynamics of {sup 6,7}Li + {sup 159}Tb reactions near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Manjeet Singh [Thapar University, School of Physics and Materials Science, Patiala (India); Indus Degree College, Department of Physics, Kinana, Jind, Haryana (India); Grover, Neha; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India)

    2017-01-15

    The complete fusion (CF) and incomplete fusion (ICF) cross-sections are estimated for {sup 6,} {sup 7}Li + {sup 159}Tb reactions using the energy-dependent Woods-Saxon potential model (EDWSP model) and dynamical cluster-decay model (DCM). The CF data of the {sup 6}Li + {sup 159}Tb({sup 7}Li + {sup 159}Tb) reaction at above barrier energies is suppressed with reference to expectations of the EDWSP model by 25% (20%) which is smaller than the reported data by ∝ 9% (6%). This suppression is correlated with the projectile breakup effect. The projectiles {sup 6,7}Li are loosely bound systems, which may break up into charged fragments prior to reaching the fusion barrier and subsequently one of the fragment is captured by the target leading to the suppression of fusion data at above barrier energies. The sum of CF and ICF, which is termed as total fusion cross-section (TF), removes the discrepancies between theoretical predictions and the above barrier complete fusion data and hence is adequately explained via the EDWSP model over a wide range of energy spread across the Coulomb barrier. In addition to fusion, the decay mechanism of {sup 6}Li + {sup 159}Tb reaction is studied within the framework of the dynamical cluster-decay model (DCM). The breakup of the projectile ({sup 6}Li) in the entrance channel indicates the presence of ICF, which is investigated further using the collective clusterization approach of DCM. The present theoretical analysis suggests that a larger barrier modification is needed to address the fusion data of chosen reactions in the below barrier energy region. (orig.)

  3. Autocatalysis in Reaction Networks

    OpenAIRE

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2013-01-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view to...

  4. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  5. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  6. Electron induced break-up of helium. Benchmark experiments on a dynamical four-body Coulomb system

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, M.

    2006-07-05

    This work presents an experimental study of fragmentation of helium by electron impact, in which absolute fully differential cross sections for single ionization, ionization-excitation and double ionization were determined. By applying a charged-particle imaging technique, the so-called 'reaction microscope', a large fraction of the final-state momentum space is covered, and the major limitations of previous experimental methods applied in this field could be overcome. Decisive modifications of the previous reaction microscope were undertaken, the most important one being the arrangement of the projectile beam parallel to the imaging-fields. For single ionization on helium an enhanced electron emission outside the projectile scattering plane is observed at both considered impact energies (102 eV and 1 keV), which is similar to the result found for ion-impact (M. Schulz et al., Nature (London) 422, 48 (2003)). The angle resolved cross sections obtained for double ionization at 105 eV impact energy reveal, that the process is dominated by the mutual repulsion of the three final-state continuum electrons. However, signatures of more complex dynamics are also observed. The data provide an ultimate benchmark for recently developed theories treating the dynamical three- and four-body Coulomb problem. (orig.)

  7. Dissertation: Precompound Emission of Energetic Light Fragments in Spallation Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-04

    Emission of light fragments (LF) from nuclear reactions is an open question. Different reaction mechanisms contribute to their production; the relative roles of each, and how they change with incident energy, mass number of the target, and the type and emission energy of the fragments is not completely understood. None of the available models are able to accurately predict emission of LF from arbitrary reactions. However, the ability to describe production of LF (especially at energies ≳ 30 MeV) from many reactions is important for different applications, such as cosmic-ray-induced Single Event Upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe quite well the spectra of fragments with sizes up to ⁴He across a broad range of target masses and incident energies (up to ~ 5 GeV for CEM and up to ~ 1 TeV/A for LAQGSM). However, they do not predict the high energy tails of LF spectra heavier than ⁴He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of the CEM and LAQGSM event generators do not account for precompound emission of LF larger than ⁴He. The aim of our work is to extend the precompound model in them to include such processes, leading to an increase of predictive power of LF-production in MCNP6. This entails upgrading the Modified Exciton Model currently used at the preequilibrium stage in CEM and LAQGSM. It also includes expansion and examination of the coalescence and Fermi break-up models used in the precompound stages of spallation reactions within CEM and LAQGSM. Extending our models to include emission of fragments heavier than ⁴He at the precompound stage has indeed provided results that have much

  8. Experimental data on fission and (n,xn) reactions; Donnees experimentales de fission et de reactions (n,xn)

    Energy Technology Data Exchange (ETDEWEB)

    Belier, G.; Chatillon, A.; Granier, T.; Laborie, J.M.; Laurent, B.; Ledoux, X.; Taieb, J.; Varignon, C.; Bauge, E.; Bersillon, O.; Aupiais, J.; Le Petit, G. [CEA Bruyeres-le-Chatel, 91 (France); Authier, N.; Casoli, P. [CEA Valduc, 21 - Is-sur-Tille (France)

    2011-07-15

    Investigations on neutron-induced fission of actinides and the deuteron breakup are presented. Neutron-induced fission has been studied for 10 years at the WNR (Weapons Neutron Research) neutron facility of the Los Alamos Neutron Science Center (LANSCE). Thanks to this white neutron source the evolution of the prompt fission neutron energy spectra as a function of the incident neutron energy has been characterized in a single experiment up to 200 MeV incident energy. For some isotopes the prompt neutron multiplicity has been extracted. These experimental results demonstrated the effect on the mean neutron energy of the neutron emission before scission for energies higher than the neutron binding energy. This extensive program ({sup 235}U and {sup 238}U, {sup 239}Pu, {sup 237}Np and {sup 232}Th were measured) is completed by neutron spectra measurements on the CEA 4 MV accelerator. The D(n,2n) reaction is studied both theoretically and experimentally. The cross-section was calculated for several nucleon-nucleon interactions including the AV18 interaction. It has also been measured on the CEA 7 MV tandem accelerator at incident neutron energies up to 25 MeV. Uncertainties lower than 8% between 5 and 10 MeV were obtained. In particular these experiments have extended the measured domain for cross sections. (authors)

  9. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  10. [Adverse reactions to vaccines].

    Science.gov (United States)

    Ito Tsuchiya, F M; Rosas Vargas, M A; Zepeda Ortega, B; Río del Navarro, Blanca Estela; Sienra Monge, Juan José Luis

    2007-01-01

    Vaccination is one of the medicine's achievements to control and/or eradicate certain infectious diseases. Vaccines contain antigenic doses derived from microorganisms and/or its toxins, besides they are composed of other substances such as aluminum, gelatin, egg proteins, mercury components (as thimerosal), and antibiotics; therefore, these substances can produce hypersensitivity reactions. The above-mentioned reactions can be evidenced with itch, edema, hives, asthmatic crisis, hypotension and even anaphylactic shock. Due to the importance of vaccination, especially in childhood, it is essential to know the benefits of vaccines, their impact in morbidity and mortality decrease of certain infected-contagious diseases, as well as the adverse effects and the allergic reactions to their application. As immunizations prevent natural infections, they might contribute to a free infectious environment that would allow atopic response. This paper reviews the allergic reactions to vaccines and their influence on the development of atopic disease.

  11. Bad Reaction to Cosmetics?

    Science.gov (United States)

    ... Consumers Protect Yourself Health Fraud Bad Reactions to Cosmetics? Tell FDA! Share Tweet Linkedin Pin it More ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products

  12. Reactor for exothermic reactions

    Science.gov (United States)

    Smith, Jr., Lawrence A.; Hearn, Dennis; Jones, Jr., Edward M.

    1993-01-01

    A liquid phase process for oligomerization of C.sub.4 and C.sub.5 isoolefins or the etherification thereof with C.sub.1 to C.sub.6 alcohols wherein the reactants are contacted in a reactor with a fixed bed acid cation exchange resin catalyst at an LHSV of 5 to 20, pressure of 0 to 400 psig and temperature of 120.degree. to 300.degree. F. Wherein the improvement is the operation of the reactor at a pressure to maintain the reaction mixture at its boiling point whereby at least a portion but less than all of the reaction mixture is vaporized. By operating at the boiling point and allowing a portion of the reaction mixture to vaporize, the exothermic heat of reaction is dissipated by the formation of more boil up and the temperature in the reactor is controlled.

  13. Firefighter Nozzle Reaction

    DEFF Research Database (Denmark)

    Chin, Selena K.; Sunderland, Peter B.; Jomaas, Grunde

    2017-01-01

    to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert...... on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand......Nozzle reaction and hose tension are analyzed using conservation of fluid momentum and assuming steady, inviscid flow and a flexible hose in frictionless contact with the ground. An expression that is independent of the bend angle is derived for the hose tension. If this tension is exceeded owing...

  14. Chemical burn or reaction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000059.htm Chemical burn or reaction To use the sharing features on ... the burned area from pressure and friction. Minor chemical burns will generally heal without further treatment. However, if ...

  15. Adverse reaction to tetrazepam.

    Science.gov (United States)

    Palacios Benito, R; Domínguez Ortega, J; Alonso Llamazares, A; Rodríguez Morales, A; Plaza Díaz, A; Chamorro Gómez, M; Martínez-Cócera, C

    2001-01-01

    Adverse reactions caused by benzodiazepines rarely occur. We present a case of a 70-year-old man who developed a maculopapular exanthema after the ingestion of tetrazepam. For his diagnosis, skin tests were performed, including prick and patch tests, not only with the benzodiazepine implicated in the reaction, but also with benzodiazepines of other groups. Single-blind oral challenge tests were also performed in the patient, in order to assess his tolerance to other benzodiazepines.

  16. Oxygen evolution reaction catalysis

    Science.gov (United States)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  17. Photoinduced Multicomponent Reactions.

    Science.gov (United States)

    Garbarino, Silvia; Ravelli, Davide; Protti, Stefano; Basso, Andrea

    2016-12-12

    The combination of multicomponent approaches with light-driven processes opens up new scenarios in the area of synthetic organic chemistry, where the need for sustainable, atom- and energy-efficient reactions is increasingly urgent. Photoinduced multicomponent reactions are still in their infancy, but significant developments in this area are expected in the near future. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Cross sections and tensor analyzing powers A_yy of the reaction ^1H(|vec|d,pp)n in SCRE geometries at E_d=19 MeV

    Energy Technology Data Exchange (ETDEWEB)

    J. Ley; C. Dueweke; A. Emmerich; A. Imig; H. Paez gen. Schieck; J. Golak; H. Witala; Evgeny Epelbaum; A. Deltuva; A. C. Fonseca; W. Gloeckle; Ulf-G. Meissner; A. Nogga; P. U. Sauer

    2006-02-01

    We measured the cross sections and tensor analyzing powers of the 1H({approx}d,pp)n breakup reaction at Ed=19 MeV in four symmetric constant relative energy (SCRE) configurations. The data are compared with theoretical predictions from three different approaches: one based on high precision (semi)phenomenological potentials alone or combined with model three-nucleon forces, another on chiral forces up to next-to-next-to-leading order (NNLO) in the chiral expansion. In both cases, the Coulomb interaction is not included. In addition, a comparison to predictions based on CD Bonn including the Lambda excitation and the Coulomb force is presented. In all cases the measured cross sections are significantly below the theoretical values whereas the magnitude of the tensor analyzing powers agree within the error bars in three of the four cases. The apparent discrepancies in the breakup cross sections are similar to the known differences for the space-star breakup. This adds to the data base of unsolved low-energy discrepancies.

  19. Direct Imaging by Cryo-TEM Shows Membrane Break-up by Phospholipase A2 Enzymatic Activity

    DEFF Research Database (Denmark)

    Callisen, Thomas Hønger; Talmon, Y.

    1998-01-01

    increase our insight into the function of PLA2 under physiological conditions as well as into general interfacial catalysis. In the present study we apply for the first time cryo-transmission electron microscopy (cryo-TEM) and high-performance liquid chromatography (HPLC) to characterize the PLA2...... hydrolysis of phospholipid vesicles with respect to changes in lipid composition and morphology. Our direct experimental results show that the initial reaction conditions are strongly perturbed during the course of hydrolysis, Most strikingly, cryo-TEM reveals that starting in the lag phase, vesicles become...... perforated and degrade into open vesicles, bilayer fragments, and micelles, This structural instability extends throughout the system in the activity burst regime. In agreement with earlier reported correlations between initial phospholipase activity and substrate morphology, our results suggest that the lag...

  20. 187Re - 232Th - 238U nuclear geochronometry: constraining magmatism in East-Antarctica and the break-up of Gondwana

    Science.gov (United States)

    Roller, Goetz

    2017-04-01

    187Re - 232Th - 238U nuclear geochronometry is a new dating method for astronomy, earth and planetary sciences [1-4]. Nucleogeochronometric Rhenium-Osmium two-point-isochron (TPI) ages are calculated using a nuclear geochronometer as one data point in a two-point-isochron diagram [5-7]. The IVREA chronometer, for example, is one of five terrestrial nuclear geochronometers identified so far [8]. Here, it is used to constrain the magmatism of the Ferrar flood basalt province, which has been related to continental rifting and the break-up of Gondwana in the Jurassic.TPI ages for seven (basaltic) andesite whole rock samples from the Prince Albert Mountains (Victoria Land, Antarctica) are calculated. An isochron age of 172 ± 5 Ma (187Os/188Osi = 0.194 ± 0.023) has previously been published for these rocks [9]. Initial TPI 187Os/188Osi ratios show only minor scatter between 187Os/188Osi = 0.2149 ± 0.0064 and 187Os/188Osi = 0.22231 ± 0.00080, in agreement with the enigmatic, suprachondritic 187Os/188Osi = 0.194 ± 0.023 from the isochron [9]. TPI ages for the Mount Joyce samples range from 125.4 ± 9.9 Ma to 139 ± 17 Ma and thus constrain the youngest magmatic event(s) in the Transantarctic Mountains. For the Thumb Point basalt, a TPI age of 219 ± 81 Ma is calculated. Despite of its large uncertainty, the age itself is in agreement with the Triassic 224 Ma and 240 Ma events reported from North Patagonia [10]. The TPI age of 186.1 ± 8.1 Ma from the Ricker Hill basalt can be clearly distinguished from the Mount Murray TPI age of 158 ± 14 Ma, while at Brimstone Peak two TPI age groups of 155 ± 14 Ma and 175.3 ± 3.1 Ma are observed. From this it may be concluded that the seven TPI ages indicate episodic magmatic activity in East-Antarctica between 125 Ma and 219 Ma, leading to the break-up of Gondwana. This picture is consistent with the geochronology of the Antarctic Peninsula, Patagonia, the Karoo and the Ferrar mafic rocks [10]. Thus, besides constraining

  1. Medications and Drug Allergic Reactions

    Science.gov (United States)

    ... drug allergic reactions TTR Share | Medications and Drug Allergic Reactions This article has been reviewed by Thanai Pongdee, ... your symptoms are severe, seek medical help immediately. Allergic Reactions Allergy symptoms are the result of a chain ...

  2. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  3. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

    of merit. Specifically, it preserves symmetry between negative evaluations of antimeritocratic bases of selection and negative evaluations of qualifications rooted in comparable antimeritocratic reactions. So if employers should not select among applicants on the basis of their (the employers') racial...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...... reaction-qualifications are entirely irrelevant from the point of view of merit, the view expounded here implies that the ideal of meritocracy and the norm of non-discrimination are less closely tied than theorists like Andrew Mason and David Miller believe.  ...

  4. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T

    2005-01-01

    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... of these (73%) the suspected cause did not match the results of subsequent investigation, either a different substance being the cause or no cause being found. Only five cases (7%) showed a complete match between suspected cause and investigation result. In the remaining 13 cases (19%) there was a partial...

  5. Hipersensitivity Reactions to Corticosteroids.

    Science.gov (United States)

    Berbegal, L; DeLeon, F J; Silvestre, J F

    2016-03-01

    Corticosteroids are widely used drugs in the clinical practice, especially by topic application in dermatology. These substances may act as allergens and produce immediate and delayed hypersensitivity reactions. Allergic contact dermatitis is the most frequent presentation of corticosteroid allergy and it should be studied by patch testing in specific units. The corticosteroids included in the Spanish standard battery are good markers but not ideal. Therefore, if those makers are positive, it is useful to apply a specific battery of corticosteroids and the drugs provided by patients. Immediate reactions are relatively rare but potentially severe, and it is important to confirm the sensitization profile and to guide the use of alternative corticosteroids, because they are often necessary in several diseases. In this article we review the main concepts regarding these two types of hypersensitivity reactions in corticosteroid allergy, as well as their approach in the clinical practice. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.

  6. Nanoparticle Reactions on Chip

    Science.gov (United States)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  7. Adverse reactions to cosmetics

    Directory of Open Access Journals (Sweden)

    Dogra A

    2003-03-01

    Full Text Available Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly shaving creams caused more reaction as compared to other cosmetics. Overall incidence of contact allergic dermatitis seen was 3.3% with patients own cosmetics. Patch testing was also done with the basic ingredients and showed positive results in few cases where casual link could be established. It is recommended that labeling of the cosmetics should be done to help the dermatologists and the patients to identify the causative allergen in cosmetic preparation.

  8. Simultaneous examination of tear film break-up and the lipid layer of the human eye: a novel model eye for time course simulation of physiologic tear film behavior (Part 2).

    Science.gov (United States)

    Arnold, Stefan; Bruenner, Holger; Langenbucher, Achim

    2010-01-01

    This article describes a model eye created to mimic the three-layered human tear-film. The model replicates the properties of the mucin, liquid and lipid layer as well as the time-course behavior including blinking process and tear film break-up for measurements with the tear film sensor described in Part 1. The setup basically consists of a sphere that is moistened by a dilution of tear film substitute. Therefore, the time point of the first break-up strongly depends on the consistency of the dilution. By means of an integrated heater, the evaporation rate of the artificial tear-film can be increased. To illustrate the applicability of the model eye, exemplary images during tear-film simulation, taken with and without using the heater, are shown. All images were captured by the sensor. Results and other potential applications are briefly discussed. Copyright © 2010. Published by Elsevier GmbH.

  9. Velocity pump reaction turbine

    Science.gov (United States)

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  10. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)

    2007-07-01

    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  11. A foraminiferal study on Middle Eocene-Oligocene break-up unconformity in northern Taiwan and its correlation with IODP Site U1435 to constrain the onset event of South China Sea opening

    Science.gov (United States)

    Huang, Chi-Yue; Shea, Kai-Hsuan; Li, Qianyu

    2017-05-01

    Taiwan is situated in the SE Asian continental margin where lower Cenozoic strata are well exposed. Its geological and tectonic setting provides a unique opportunity to study the time constraint of the break-up unconformity relevant to the opening of the South China Sea. A detailed foraminiferal study on four land sections and a deep core across the boundary between the Upper and Lower Wulai Groups in the Hsüehshan Range, northern Taiwan, was conducted. Results show remarkable changes of depositional environment and lithology from the amalgamated fluvial dominant sandstones (>2000 m) of Middle Eocene in the Lower Wulai Group to the overlying inner neritic shales and siltstones (>2000 m) of Oligocene in the Upper Wulai Group. Integrated sedimentological and foraminiferal data further suggest an occurrence of a depositional hiatus between 32 ∼33 and 40 Ma across the boundary between the Kankou Formation of the Upper Wulai Group and the Szeleng Sandstone of the Lower Wulai Group in the northern Hsüehshan Range, as same as the scenario seen in the Western Foothills (25-39 Ma) of central Taiwan and the Penghu Basin (25-40 Ma) in the Taiwan Strait. This stratigraphic hiatus in the Taiwan mountain belt marks a regional break-up unconformity between the Middle Eocene syn-rift strata and the overlying Oligocene post-rift sequences in the NE South China Sea. The break-up unconformity can be correlated with those commonly recognized in the seismic profiles of the Pearl River Mouth Basin and drilling of the IODP site U1435 (Expedition 349) in the northern shelf-slope of the South China Sea. The upper time limit of the breakup unconformity 32 Ma could mark the tectonic change from rifting to depression in the Paleogene Asian continental margin which eventually led to opening of the deep South China Sea in the Early Oligocene (∼33 Ma).

  12. Comparison of non-invasive tear break-up time and tear meniscus height in healthy eyes and keratoconus using Oculus Keratograph 5M

    Directory of Open Access Journals (Sweden)

    Masoud Safarzadeh

    2017-09-01

    Full Text Available AIM: To compare the non-invasive tear break-up time(NITBUTand tear meniscus height(TMHmeasurements in keratoconus patients and normal subjects, and to determine the relationship between these measurements with keratoconus disease by the Oculus Keratograph 5M(K5M. METHODS:Fifty keratoconus patients(100 eyesand 50 healthy subjects(100 eyesparticipated in the study. The age range in keratoconus group was 15-60(mean ± standard deviation=28.33±8.60y, and in control group was 18-60(26.25±1.11y. The measurements of NITBUT and TMH were performed using the K5M. RESULTS: The mean value of NITBUT between the keratoconus group and the control group showed no statistically significant different(P=0.58. Also, the mean of TMH between two groups was not significantly different(P=0.69. The results of correlation coefficient between the variables of the study demonstrated that there was no significant relationship between the NITBUT and TMH measurements with the two groups(keratoconus group: r= 0.053, P=0.721; control group; r=-0.0501, P=0.7098. CONCLUSION: Our study shows that the presence of keratoconus has no clinically significant impact on the quality and quantity of tear film.

  13. Erosion and break-up of light-gas layers by a horizontal jet in a multi-vessel, large-scale containment test system

    Energy Technology Data Exchange (ETDEWEB)

    Zboray, Robert, E-mail: robert.zboray@psi.ch; Mignot, Guillaume; Kapulla, Ralf; Paladino, Domenico

    2015-09-15

    The distribution and eventual stratification of hydrogen released during a hypothetical severe accident and the stability of the stratification formed in the early phase of the transient is of particular safety concern in Light Water Reactors (LWRs). The large-scale containment test facility PANDA (PSI, Switzerland) has been used to perform a series of four tests examining the erosion and break-up of stratified light-gas layers in the frame of the OECD SETH-2 project. The ultimate goal of the test program is to set-up an experimental data base of high-quality and high-density data that can challenge and validate 3D containment codes like e.g. GOTHIC, GASFLOW or MARS and validate the applicability of CFD codes like FLUENT or CFX for LWR containment problems. The test series discussed here focuses on the erosion of a stratified, helium-rich layer by horizontal steam injection at different locations below the layer. An approach with step-wise increasing complexity has been chosen to examine this problem allowing control over the rate of pressure increase and the occurrence of condensation. The step-wise approach enables a thorough understanding of the influence of different phenomena like position of steam injection, diffusion, pressurization and condensation on the behavior and erosion of the stratified layer.

  14. The association of vitamin D deficiency with tear break-up time and Schirmer testing in non-Sjögren dry eye.

    Science.gov (United States)

    Kurtul, B E; Özer, P A; Aydinli, M S

    2015-08-01

    To investigate the effect of vitamin D deficiency on tear break-up time (TBUT) and Schirmer test scores and to assess their relationship in non-Sjögren dry-eye patients. Thirty-four patients with serum vitamin D deficiency and 21 control subjects with normal vitamin D levels were included in this study. The TBUT and Schirmer-1 test without topical anesthesia were performed to all patients. The mean TBUT were 5.18±2.15 and 7.36±3.10 s and Schirmer scores were 12.18±6.44 and 18.57±8.99 mm in the study and control groups, respectively. TBUT scores and Schirmer-1 results of the study group were significantly lower than the control group (P=0.01 and 0.007, respectively). The mean vitamin D levels were 11.50±1.8 ng/ml in the study group and 32.8±8.72 ng/ml in control group (P=0.001). Dry-eye symptoms were detected in all patients in the study group and 15% of the patients in the control group. We demonstrated that vitamin D deficiency decreases the TBUT and Schirmer test values and may be associated with dry-eye symptoms in non-Sjögren syndrome.

  15. Particle aerosolisation and break-up in dry powder inhalers: evaluation and modelling of the influence of grid structures for agglomerated systems.

    Science.gov (United States)

    Wong, William; Fletcher, David F; Traini, Daniela; Chan, Hak-Kim; Crapper, John; Young, Paul M

    2011-11-01

    This study aimed to investigate the influence of grid structures on the break-up and aerosol performance of a model inhalation formulation through the use of standardised entrainment tubes in combination with computational fluid dynamics (CFD). A series of entrainment tubes with grid structures of different aperture size and wire diameters were designed in silico and constructed using three-dimensional printing. The flow characteristics were simulated using CFD, and the deposition and aerosol performance of a model agglomerate system (496.3-789.2 µm agglomerates containing 3.91 µm median diameter mannitol particles) were evaluated by chemical analysis and laser diffraction, respectively. Analysis of the mannitol recovery from the assembly indicated that mass deposition was primarily on the grid structure with little before or after the grid. Mass deposition was minimal down to 532 µm; however, for smaller grid apertures, significant blockage was observed at all airflow rates (60-140 L · min(-1)). Analysis of the particle size distribution exiting the impactor assembly suggested that mannitol aerosolisation was dependent on the void percentage of the grid structure. It is proposed that initial particle-grid impaction results in a shearing force causing agglomerate fragmentation followed by immediate re-entrainment into the turbulent airstream within the grid apertures which causes further dispersion of the fine particles. Such observations have significant implications in the design of dry powder inhaler devices. Copyright © 2011 Wiley-Liss, Inc.

  16. Denudation of SW Iberia during Pangeá s break-up: geochemical and detrital zircon geochronology characterization of Triassic basins

    Science.gov (United States)

    Pereira, Manuel F.; Ribeiro, Carlos; Vilallonga, Filipa; Chichorro, Martim; Drost, Kerstin

    2010-05-01

    This provenance study is mainly based on new whole-rock geochemistry data but also involves detrital zircon geochronology. More specifically, this study investigates the Early Mesozoic denudation of a Late Paleozoic mountain range, and the coeval development of basins during Pangea break-up in SW Iberia. The relations with past dynamic Earth events in Western Europe also include the amalgamation of Pangea and the development of the Carboniferous basins. U-Pb LA-ICP-MS geochronology on detrital zircons complemented by geochemical data of siliciclastic sediments is a powerful tool for the study of the sediments' provenance, particularly in constraining the paleogeography, the tectonic reconstructions, and the crustal evolution. The use of zircon geochronology can be a balancing tool useful for the elucidation of the uplift rates and the establishment of the behaviour of different crustal blocks related to intra-continental tectonics. The objects of this study are the siliciclastic sediments that define one of the most profound unconformities of the Early Mesozoic: the basal unconformity where late Triassic strata overlie late Carboniferous basement previously deformed and metamorphosed. This important stratigraphic boundary records the transition from the timely stages of Pangeás amalgamation to the early stages of its break-up. In SW Iberia the record of Pangea formation and break-up is associated to significant siliciclastic sedimentation arising from mountain building, rifting and up-lift processes. During the Triassic sedimentation in the different blocks of Pangea was dominated by a series of coalescing, alluvial-deltaic wedges and axial braided rivers that filled the foreland basins. As the foreland basins were filled, the excess detritus was transported across the craton by fluvial and aeolian processes. This sedimentation formed a complex of inter-fingered basins related to the continental break-up and coeval with the infill of other basins associated to the

  17. 40Ar/ 39Ar dating of the Jurassic volcanic province of Patagonia: migrating magmatism related to Gondwana break-up and subduction

    Science.gov (United States)

    Féraud, G.; Alric, V.; Fornari, M.; Bertrand, H.; Haller, M.

    1999-10-01

    The Mesozoic large igneous province (LIP) of Patagonia (southern South America), which is one of the largest silicic provinces on Earth has been investigated by the 40Ar/ 39Ar method. Twenty-seven ages considered as valid, including twenty plateau ages, show that the volcanic activity, ranging from 187 to 144 Ma, occurred between and contemporaneously with the initial break-up of Gondwana (starting with the Karoo-Antarctic-Tasmanian (KAT) flood basalt province) in the east, and a subduction in the west. The data display a regular decreasing of ages from the ENE (187 Ma) to the WSW (144 Ma) along about 650 km, apparently related to the tectonic structure in half-grabens oriented NNW-SSE. The good fitting of this trend with the opening of the Rocas Verdes-Sarmiento marginal basin favors a space time evolution of this continental volcanism culminating towards the SSW in a continental disruption behind the magmatic arc. The observed age progression of volcanism may be the result of the variations of the physical characteristics of the subduction. The spreading and thermal effect of the KAT plume may have an additional effect and also could account for the unusually large volume of magma.

  18. Moving Towards a State of the Art Charge-Exchange Reaction Code

    Science.gov (United States)

    Poxon-Pearson, Terri; Nunes, Filomena; Potel, Gregory

    2017-09-01

    Charge-exchange reactions have a wide range of applications, including late stellar evolution, constraining the matrix elements for neutrinoless double β-decay, and exploring symmetry energy and other aspects of exotic nuclear matter. Still, much of the reaction theory needed to describe these transitions is underdeveloped and relies on assumptions and simplifications that are often extended outside of their region of validity. In this work, we have begun to move towards a state of the art charge-exchange reaction code. As a first step, we focus on Fermi transitions using a Lane potential in a few body, Distorted Wave Born Approximation (DWBA) framework. We have focused on maintaining a modular structure for the code so we can later incorporate complications such as nonlocality, breakup, and microscopic inputs. Results using this new charge-exchange code will be shown compared to the analysis in for the case of 48Ca(p,n)48Sc. This work was supported in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through the U.S. DOE Cooperative Agreement No. DE- FG52-08NA2855.

  19. cyclopropanation reaction with ketene

    Indian Academy of Sciences (India)

    Administrator

    Smith. 15. This has motivated a large number of research groups to develop new and wide-range methods to produce cyclopropanated products. Methylene insertion by a carbenoid species into the. C=C bond is one of the most widely used methods since the recognition of the Simmons–Smith reac- tion, which is a reaction ...

  20. Reaction product imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  1. Reaction Formulation: A Bibliography.

    Science.gov (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    Reaction formation was studied by Sigmund Freud. This defense mechanism may be related to repression, substitution, reversal, and compensation (or over-compensation). Alfred Adler considered compensation a basic process in his individual psychology. Anna Freud discussed some defense mechanisms, and Bibring, Dwyer, Huntington, and Valenstein…

  2. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive

  3. Cluster knockout reactions

    Indian Academy of Sciences (India)

    2014-04-07

    Apr 7, 2014 ... Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it ...

  4. Light Particle Emission Mechanisms in Heavy-Ion Reactions at 5-20 MeV/u

    Directory of Open Access Journals (Sweden)

    Fotina O.V.

    2010-03-01

    Full Text Available Light Charged Particle emission mechanisms were studied for different mass entrance channel nuclear reactions. The 300, 400, 500 MeV 64Ni + 68Zn and 130, 250 MeV 16O + 116Sn reactions were measured at the Legnaro National Laboratory using the beams from the TANDEM-ALPI acceleration system. Light Charged Particles were measured in coincidence with Evaporation Residues and their spectra were analyzed using the global moving source fit technique. The characterization of different emission sources (evaporative, pre-equilibrium, break-up is discussed. The behavior of pre-equilibrium emission as a function of projectile energy, excitation energy and mass-asymmetry in the entrance channel was studied, evaluating the energy, mass and charge lost by the composite systems and using Griffin exciton model for the pre-equilibrium neutron emission. The present results are compared with the systematics of the asymmetric mass entrance channel reactions. The present work shows that also at the onset the pre-equilibrium emission depends not only on the projectile velocity but also on the reaction entrance channel mass-asymmetry. The first attempt of the particle spectra analysis using the Griffin exciton model is demonstrated for the case of proton emission in the 130 MeV 16O + 116Sn reaction.

  5. Transfer reactions with HELIOS

    Science.gov (United States)

    Wuosmaa, Alan H.

    2011-04-01

    Nucleon-transfer reactions have formed the backbone of nuclear-structure studies for several decades, providing a wealth of information about the energies, quantum numbers, and wave functions of single-particle states in nuclei throughout the nuclear chart. Current trends in nuclear-structure physics and the modern emphasis on properties of neutron-rich nuclei far from stability have renewed interest in such transfer reactions with radioactive beams. Here, the usual combination of light beam and heavy target cannot be used, and measurements must be performed in ``inverse kinematics,'' with a heavy, unstable beam incident on a light target. This arrangement introduces several technical difficulties, including the identification of the reaction products and the resolution of the states of interest in the residual nuclei. A new device, HELIOS (the HELIcal Orbit Spectrometer) at the ATLAS facility at Argonne National Laboratory, solves many of the problems encountered with inverse kinematics including particle identification and energy resolution in the center-of-mass frame. The device utilizes the uniform magnetic field of a large, superconducting solenoid to transport light reaction products from the target to a linear array of position-sensitive silicon detectors. The properties of HELIOS will be described, and examples from the initial research program that focuses on neutron transfer with the (d,p) reaction, using both stable and unstable beams with mass A = 11 to 136, will be presented. Work supported by the U. S. Department of Energy, Office of Nuclear Physics under contract numbers DE-FG02-04ER41320 (WMU) and DE-AC02-06CH11357 (ANL).

  6. Multicomponent reactions in polymer synthesis.

    Science.gov (United States)

    Kakuchi, Ryohei

    2014-01-03

    More participants, yet efficient reactions: Multicomponent reactions (MCRs) have found application in polymer chemistry both in the synthesis of multifunctional monomers and in post-polymerization modification. Examples include the Passerini three-component reaction, the Ugi four-component reaction, and the copper-catalyzed MCR. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    Villadsen, John

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions. The mo...

  8. What Is a Reaction Rate?

    Science.gov (United States)

    Schmitz, Guy

    2005-01-01

    The definition of reaction rate is derived and demonstrations are made for the care to be taken while using the term. Reaction rate can be in terms of a reaction property, the extent of reaction and thus it is possible to give a definition applicable in open and closed systems.

  9. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  10. Reactions to dietary tartrazine.

    Science.gov (United States)

    David, T J

    1987-01-01

    Double blind challenges with tartrazine and benzoic acid were performed in hospital in 24 children whose parents gave a definite history of a purely behavioural immediate adverse reaction to one of these substances. The patients, whose ages ranged from 1.6 to 12.4 years, were on a diet that avoided these items, and in all there was a clear history that any lapse of the diet caused an obvious adverse behavioural reaction within two hours. In no patient was any change in behaviour noted either by the parents or the nursing staff after the administration of placebo or active substances. Twenty two patients returned to a normal diet without problems, but the parents of two children insisted on continuing the diet. While popular belief has it that additives may have harmful behavioural effects, objective verification is required to prevent overdiagnosis. PMID:3548601

  11. Enzyme catalysed tandem reactions.

    Science.gov (United States)

    Oroz-Guinea, Isabel; García-Junceda, Eduardo

    2013-04-01

    To transfer to the laboratory, the excellent efficiency shown by enzymes in Nature, biocatalysis, had to mimic several synthetic strategies used by the living organisms. Biosynthetic pathways are examples of tandem catalysis and may be assimilated in the biocatalysis field for the use of isolated multi-enzyme systems in the homogeneous phase. The concurrent action of several enzymes that work sequentially presents extraordinary advantages from the synthetic point of view, since it permits a reversible process to become irreversible, to shift the equilibrium reaction in such a way that enantiopure compounds can be obtained from prochiral or racemic substrates, reduce or eliminate problems due to product inhibition or prevent the shortage of substrates by dilution or degradation in the bulk media, etc. In this review we want to illustrate the developments of recent studies involving in vitro multi-enzyme reactions for the synthesis of different classes of organic compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. CMLSnap : Animated reaction mechanisms

    OpenAIRE

    Holliday, Gemma L; Mitchell, John BO; Murray-Rust, Peter

    2004-01-01

    The authors thank the EPSRC for financial support of this project and Unilever for their support of the Centre for Molecular Science Informatics. Reactions with many steps can be represented by a single XML-based table of the atoms, bonds and electrons. For each step the complete Chemical Markup Language 1 representation of all components is obtained and a snapshot representing the end point of the step is generated. These snapshots can then be combined to give an animated description of t...

  13. Exclusive reactions in QCD

    OpenAIRE

    Pire, Bernard

    1996-01-01

    We review the theory of hard exclusive scattering in Quantum Chromodynamics. After recalling the classical counting rules which describe the leading scale dependence of form factors and exclusive cross-sections at fixed angle, the pedagogical example of the pion form factor is developped in some detail in order to show explicitely what factorization means in the QCD framework. The picture generalizes to many hard reactions which are at the heart of the ELFE project. We briefly present the con...

  14. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

    1993-12-01

    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

  15. Cryochemical chain reactions

    Science.gov (United States)

    Barkalov, I. M.; Kiryukhin, D. P.

    The possibility of a chemical reaction near absolute zero has appeared doubtful since the beginning of the 1970s. The existing ideas must be revised after the radiation polymerization of formaldehyde at 4.2 K has been observed. In glassy systems, we have examined chain processes that occur under sharp (by five to six orders) changes in molecular mobility of the medium in the region of matrix devitrification. Quite unusual mechano-energetic chains of chemical conversion arise in the studied systems submerged in liquid helium. The chemical transformation initiated by local brittle fracture travels over the sample as an autowave. A series of experimental and theoretical investigations devoted to this interesting phenomenon are described. There is no generalization in this new region of chemistry up to this time. Many journal articles and reviews have been previously published only in Russian. The cycles of investigations of chain cryochemical reactions are the subject of this review. We hope that the investigation of the extraordinary peculiarities of chain cryochemical reactions should produce new ideas in chemical theory and industry.

  16. Adverse cutaneous drug reaction

    Directory of Open Access Journals (Sweden)

    Nayak Surajit

    2008-01-01

    Full Text Available In everyday clinical practice, almost all physicians come across many instances of suspected adverse cutaneous drug reactions (ACDR in different forms. Although such cutaneous reactions are common, comprehensive information regarding their incidence, severity and ultimate health effects are often not available as many cases go unreported. It is also a fact that in the present world, almost everyday a new drug enters market; therefore, a chance of a new drug reaction manifesting somewhere in some form in any corner of world is unknown or unreported. Although many a times, presentation is too trivial and benign, the early identification of the condition and identifying the culprit drug and omit it at earliest holds the keystone in management and prevention of a more severe drug rash. Therefore, not only the dermatologists, but all practicing physicians should be familiar with these conditions to diagnose them early and to be prepared to handle them adequately. However, we all know it is most challenging and practically difficult when patient is on multiple medicines because of myriad clinical symptoms, poorly understood multiple mechanisms of drug-host interaction, relative paucity of laboratory testing that is available for any definitive and confirmatory drug-specific testing. Therefore, in practice, the diagnosis of ACDR is purely based on clinical judgment. In this discussion, we will be primarily focusing on pathomechanism and approach to reach a diagnosis, which is the vital pillar to manage any case of ACDR.

  17. Modelling Tethered Enzymatic Reactions

    Science.gov (United States)

    Solis Salas, Citlali; Goyette, Jesse; Coker-Gordon, Nicola; Bridge, Marcus; Isaacson, Samuel; Allard, Jun; Maini, Philip; Dushek, Omer

    Enzymatic reactions are key to cell functioning, and whilst much work has been done in protein interaction in cases where diffusion is possible, interactions of tethered proteins are poorly understood. Yet, because of the large role cell membranes play in enzymatic reactions, several reactions may take place where one of the proteins is bound to a fixed point in space. We develop a model to characterize tethered signalling between the phosphatase SHP-1 interacting with a tethered, phosphorylated protein. We compare our model to experimental data obtained using surface plasmon resonance (SPR). We show that a single SPR experiment recovers 5 independent biophysical/biochemical constants. We also compare the results between a three dimensional model and a two dimensional model. The work gives the opportunity to use known techniques to learn more about signalling processes, and new insights into how enzyme tethering alters cellular signalling. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).

  18. Effects of Systane® Balance on noninvasive tear film break-up time in patients with lipid-deficient dry eye

    Science.gov (United States)

    Aguilar, Alejandro J; Marquez, Maria I; Albera, Paula A; Tredicce, Jorge L; Berra, Alejandro

    2014-01-01

    Purpose To evaluate the ability of Systane® Balance (SYSB) administered four times per day for 4 weeks to increase noninvasive tear film break-up time (NITFBUT) over baseline compared with a saline (SAL) control in patients with lipid-deficient dry eye (DE). Patients and methods Patients aged ≥18 years with DE and evidence of meibomian gland dysfunction (ie, abnormal gland expression and missing meibomian glands) were included in this randomized, parallel-group, controlled, investigator-masked comparison study. Patients were randomized to SYSB or SAL four times daily for 4 weeks. The primary efficacy variable was mean change in NITFBUT from baseline at week 4. Ocular surface staining, goblet cell density, and meibomian gland expression were also assessed. Safety assessments included adverse events (AEs), best-corrected visual acuity, and ocular signs. Results A total of 49 patients received study treatments (SYSB, n=25; SAL, n=24). Most patients were women (67.4%) and Caucasian (63.3%); mean ± standard deviation (SD) age was 44±19 years. DE characteristics at baseline were similar between groups. After 4 weeks of treatment, the mean ± SD NITFBUT increase from baseline was significantly greater with SYSB (2.83±0.74 seconds) compared with SAL (0.66±0.55 seconds; P<0.001, t-test). Improvements in conjunctival and corneal staining, percentage of patients with increased goblet cell density, and meibomian gland expression were also observed with 4 weeks of SYSB over SAL. No AEs were reported for either treatment group; best-corrected visual acuity and ocular signs remained stable or improved compared with baseline. Conclusion SYSB restored tear film stability, improved ocular surface healing, and improved meibomian gland functionality after 4 weeks of use in patients with lipid-deficient DE. No AEs were reported with either SYSB or SAL. PMID:25473263

  19. Effects of Systane(®) Balance on noninvasive tear film break-up time in patients with lipid-deficient dry eye.

    Science.gov (United States)

    Aguilar, Alejandro J; Marquez, Maria I; Albera, Paula A; Tredicce, Jorge L; Berra, Alejandro

    2014-01-01

    To evaluate the ability of Systane(®) Balance (SYSB) administered four times per day for 4 weeks to increase noninvasive tear film break-up time (NITFBUT) over baseline compared with a saline (SAL) control in patients with lipid-deficient dry eye (DE). Patients aged ≥18 years with DE and evidence of meibomian gland dysfunction (ie, abnormal gland expression and missing meibomian glands) were included in this randomized, parallel-group, controlled, investigator-masked comparison study. Patients were randomized to SYSB or SAL four times daily for 4 weeks. The primary efficacy variable was mean change in NITFBUT from baseline at week 4. Ocular surface staining, goblet cell density, and meibomian gland expression were also assessed. Safety assessments included adverse events (AEs), best-corrected visual acuity, and ocular signs. A total of 49 patients received study treatments (SYSB, n=25; SAL, n=24). Most patients were women (67.4%) and Caucasian (63.3%); mean ± standard deviation (SD) age was 44±19 years. DE characteristics at baseline were similar between groups. After 4 weeks of treatment, the mean ± SD NITFBUT increase from baseline was significantly greater with SYSB (2.83±0.74 seconds) compared with SAL (0.66±0.55 seconds; P<0.001, t-test). Improvements in conjunctival and corneal staining, percentage of patients with increased goblet cell density, and meibomian gland expression were also observed with 4 weeks of SYSB over SAL. No AEs were reported for either treatment group; best-corrected visual acuity and ocular signs remained stable or improved compared with baseline. SYSB restored tear film stability, improved ocular surface healing, and improved meibomian gland functionality after 4 weeks of use in patients with lipid-deficient DE. No AEs were reported with either SYSB or SAL.

  20. Agreement of noninvasive tear break-up time measurement between Tomey RT-7000 Auto Refractor-Keratometer and Oculus Keratograph 5M.

    Science.gov (United States)

    Lee, Ryan; Yeo, Sharon; Aung, Han Tun; Tong, Louis

    2016-01-01

    It is difficult to standardize assessment of dry eye in different clinical settings. Increasingly, tear stability is recognized to be important for the definition and assessment of patients with dry eye. Recently, two commercially available instruments have been made available for objectively measuring noninvasive tear break-up time (NIBUT), as an indicator of tear stability: the Tomey RT-7000 Auto Refractor-Keratometer and Oculus Keratograph (K)5M. We aim to assess the agreement of NIBUT measurements using these modalities. This prospective cross-sectional study was carried out in a tertiary referral eye center and involved 126 consecutive dry eye patients. NIBUT assessment was performed on the right eyes of participants with both the RT-7000 and the K5M techniques, with the order of assessment randomized. The Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaires were administered to assess dry eye symptoms in the 2 weeks before assessment. The age of the participants was 56.0±14.3 years (69.84% females). Measurements for both modalities were non-normally distributed (right-skewed). The median RT-7000 and K5M readings were 4.2 (range 0.1-10.0) and 6.4 (0.1-24.9) seconds, respectively. RT-7000 and K5M readings were poorly correlated (ρ=0.061, P=0.495). Intraclass correlation coefficient between the modalities was 0.187 (95% confidence interval -0.097 to 0.406). The Bland-Altman plot showed no systematic differences between the readings with these machines. The agreement between machines was not different in different SPEED categories. While there are theoretical and practical benefits of NIBUT for assessment of tear stability over dye-based methods, the agreement between the two modalities was poor. Hence, studies and trials assessing NIBUT should avoid using these modalities interchangeably for NIBUT assessment. More research is needed to improve consensus on how to determine NIBUT.