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SPHYNX 2017 Publications

2017

 

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Other Publication Years:

2017, 2016, 2015, 2014, 2013, 2012, Older publications (2008-2011)

 
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  • "Inertial regimes in a curved electromagnetically forced flow"
  • J. Boisson, R. Monchaux and S. S. Aumaitre
    Journal of Fluid Mechanics. 813:860-881 (FEB, 2017)
Abstract: We investigated experimentally the flow driven by a Lorentz force induced by an axial magnetic field B and a radial electric current 1 Applied between two fixed concentric copper cylinders. The gap geometry corresponds to a rectangular section with an aspect ratio of eta = 4 and we probe the;Azimuthal and axial velocity profiles f the flow along the vertical axis by using ultrasonic Doppler velocimetry. We have performed several runs at moderate magnetic field strengths, corresponding to moderate Hartmann numbers M<=300. At these forcing parameters and because of the geometry of our experimental device, we show that the inertial terms are not negligible and an azimuthal velocity that depends on both I and H is induced. From measurements of the vertical velocity we focus on the characteristics of the secondary flow: the time-averaged velocity profiles are compatible with a secondary flow presenting two pairs of stable vortices, as pointed out by previous numerical studies. The flow exhibited a transition between two dynamical modes, a high- and a low-frequency one. The high-frequency mode, which emerges at low magnetic field forcing, corresponds to the propagation in the radial r-direction of tilted vortices. ''This mode is consistent with our previous experiments and with the instability described in Zhao et al. (Phys. Fluids, vol. 23 (8), 2011, 084103) taking place in an elongated duct geometry. The low-frequency mode, observed for high magnetic field forcing, consists of large excursions of the vortices. The dynamics of these modes matches the first axisymmetric instability described in Zhao & Zikanov (J. Fluid Mech., vol. 692, 2012, pp. 288-316) taking place in an square duct geometry. We demonstrated that this transition is controlled by the inertial magnetic thickness H''/ which is the characteristic length we introduce as a balance between the advection and the Lorentz force. The key point here is that when the inertial magnetic thickness H'' is comparable to one geometric characteristic length (H/2 in the vertical or Delta r in the radial direction) the corresponding mode is favoured. Therefore, when H''/ H/2) we observe the high-frequency mode taking place in an elongated duct geometry, and when H''/Delta r approximate to 1 we observe the low-frequency mode taking place in square duct geometry and high magnetic field.
BibTeX:
@article{Boisson2017,
  author = {J. Boisson and R. Monchaux and S. Aumaitre, S.},
  title = {Inertial regimes in a curved electromagnetically forced flow},
  journal = {Journal of Fluid Mechanics},
  year = {2017},
  volume = {813},
  pages = {860-881},
  doi = {10.1017/jfm.2016.876}
}
  • "Study of secondary hydriding at high temperature in zirconium based nuclear fuel cladding tubes by coupling information from neutron radiography/tomography, electron probe micro analysis, micro elastic recoil detection analysis and laser induced breakdown spectroscopy microprobe"
  • J.-C. Brachet, D. Hamon, M. L. Saux, V. Vandenberghe, C. Toffolon-Masclet, E. Rouesne, S. Urvoy, J.-L. Bechade, C. Raepsaet, J.-L. Lacour, G. Bayon and F. Ott
    Journal OF Nuclear Materials. 488:267-286 (MAY, 2017)
Abstract: This paper gives an overview of a multi-scale experimental study of the secondary hydriding phenomena that can occur in Nuclear fuel cladding materials exposed to steam at high temperature (HT) after having burst (loss-of-coolant accident conditions). By coupling information from several facilities, including neutron radiography/tomography, electron probe micro analysis, micro elastic recoil detection analysis and micro laser induced breakdown spectroscopy, it was possible to map quantitatively, at different scales, the distribution of oxygen and hydrogen within M5 (TM)(1) clad segments having experienced ballooning and burst at HT followed by steam oxidation at 1100 and 1200 degrees C and final direct water quenching down to room temperature. The results were very reproducible and it was confirmed that internal oxidation and secondary hydriding at HT of a cladding after burst can lead to strong axial and azimuthal gradients of hydrogen and oxygen concentrations, reaching 3000-4000 wt ppm and 1.0-1.2 wt% respectively within the beta phase layer for the investigated conditions. Consistent with thermodynamic and kinetics considerations, oxygen diffusion into the prior-beta layer was enhanced in the regions highly enriched in hydrogen, where the alpha(O) phase layer is thinner and the prior-beta layer thicker. Finally the induced post-quenching hardening of the prior-beta layer was mainly related to the local oxygen enrichment. Hardening directly induced by hydrogen was much less significant. (C) 2017 Elsevier B.V. All rights reserved.
BibTeX:
@article{Brachet2017,
  author = {J.-C. Brachet and D. Hamon and M. Le Saux and V. Vandenberghe and C. Toffolon-Masclet and E. Rouesne and S. Urvoy and J.-L. Bechade and C. Raepsaet and J.-L. Lacour and G. Bayon and F. Ott},
  title = {Study of secondary hydriding at high temperature in zirconium based nuclear fuel cladding tubes by coupling information from neutron radiography/tomography, electron probe micro analysis, micro elastic recoil detection analysis and laser induced breakdown spectroscopy microprobe},
  journal = {Journal OF Nuclear Materials},
  year = {2017},
  volume = {488},
  pages = {267-286},
  doi = {10.1016/j.jnucmat.2017.03.009}
}
BibTeX:
@article{Chate2017,
  author = {Chate, Hugues},
  title = {Editorial: Looking Ahead},
  journal = {Physical Review Letters},
  year = {2017},
  volume = {118},
  number = {14},
  doi = {10.1103/PhysRevLett.118.140002}
}
BibTeX:
@article{Chate2017a,
  author = {H. Chate},
  title = {Editorial: A Decade of Editors' Suggestions},
  journal = {Physical Review Letters},
  year = {2017},
  volume = {118},
  number = {3},
  doi = {10.1103/PhysRevLett.118.030001}
}
  • "Weak synchronization and large-scale collective oscillation in dense bacterial suspensions"
  • C. Chen, S. Liu, X.-Q. Shi, H. Chate and Y. Wu
    Nature. 542(7640):210-214 (FEB 9, 2017)
Abstract: Collective oscillatory behaviour is ubiquitous in nature(1), having a vital role in many biological processes from embryogenesis(2) and organ development(3) to pace-making in neuron networks(4). Elucidating the mechanisms that give rise to synchronization is essential to the understanding of biological self-organization. Collective oscillations in biological multicellular systems often arise from long-range coupling mediated by diffusive chemicals(2,5-9), by electrochemical mechanisms(4,10), or by biomechanical interaction between cells and their Physical environment(11). In these examples, the phase of some oscillatory intracellular degree of freedom is synchronized. Here, in contrast, we report the discovery of a weak synchronization mechanism that does not require long-range coupling or inherent oscillation of individual cells. We find that millions of motile cells in dense bacterial suspensions can self organize into highly robust collective oscillatory motion, while individual cells move in an erratic manner, without obvious periodic motion but with frequent, abrupt and random directional changes. So erratic are individual trajectories that uncovering the collective oscillations of our micrometre-sized cells requires individual velocities to be averaged over tens or hundreds of micrometres. On such large scales, the oscillations appear to be in phase and the mean position of cells typically describes a regular elliptic trajectory. We found that the phase of the oscillations is organized into a centimetre-scale travelling wave. We present a model of noisy self-propelled particles with strictly local interactions that accounts faithfully for our observations, suggesting that self-organized collective oscillatory motion results from spontaneous chiral and rotational symmetry breaking. These findings reveal a previously unseen type of long-range order in active matter systems (those in which energy is spent locally to produce non-random motion)(12,13). This mechanism of collective oscillation may inspire New strategies to control the self-organization of active matter(14-18) and swarming robots.
BibTeX:
@article{Chen2017,
  author = {C. Chen and S. Liu and X-Q. Shi and H. Chate and Y. Wu},
  title = {Weak synchronization and large-scale collective oscillation in dense bacterial suspensions},
  journal = {Nature},
  year = {2017},
  volume = {542},
  number = {7640},
  pages = {210-214},
  doi = {10.1038/nature20817}
}
Abstract: We report the experimental evidence of the existence of a random attractor in a fully developed turbulent swirling flow. By defining a global observable which tracks the asymmetry in the flux of angular momentum imparted to the flow, we can first reconstruct the associated turbulent attractor and then follow its route towards chaos. We further show that the experimental attractor can be modeled by stochastic Duffing equations, that match the quantitative properties of the experimental flow, namely, the number of quasistationary states and transition rates among them, the effective dimensions, and the continuity of the first Lyapunov exponents. Such properties can be recovered neither using deterministic models nor using stochastic differential equations based on effective potentials obtained by inverting the probability distributions of the experimental global observables. Our findings open the way to low-dimensional modeling of systems featuring a large number of degrees of freedom and multiple quasistationary states.
BibTeX:
@article{Faranda2017,
  author = {D. Faranda and Y. Sato and B. Saint-Michel and C. Wiertel and V. Padilla and B. Dubrulle and F. Daviaud},
  title = {Stochastic Chaos in a Turbulent Swirling Flow},
  journal = {Physical Review Letters},
  year = {2017},
  volume = {119},
  number = {1},
  doi = {10.1103/PhysRevLett.119.014502}
}
Abstract: We study the statistics of the power P dissipated by waves propagating in a one-dimensional disordered medium with damping coefficient nu. An operator imposes the wave amplitude at one end, therefore injecting a power P that balances dissipation. The typical realization of P vanishes for nu -> 0: Disorder leads to localization and total reflection of the wave energy back to the emitter, with negligible losses. More surprisingly, the mean dissipated power < P > averaged over the disorder reaches a finite limit for nu -> 0. We show that this "anomalous dissipation" lim(nu -> 0)< P > is directly given by the integrated density of states of the undamped system. In some cases, this allows us to compute the anomalous dissipation exactly, using properties of the undamped system only. As an example, we compute the anomalous dissipation for weak correlated disorder and for Gaussian white noise of arbitrary strength. Although the focus is on the singular limit nu -> 0, we finally show that this approach is easily extended to arbitrary nu.
BibTeX:
@article{Gallet2017,
  author = {B. Gallet},
  title = {Energy-dissipation anomaly in systems of localized waves},
  journal = {Physical Review E},
  year = {2017},
  volume = {95},
  number = {5},
  doi = {10.1103/PhysRevE.95.050101}
}
Abstract: Turbulent flows are known to enhance turbulent transport. It has then even been suggested that turbulence is a state of maximum energy dissipation. In this paper, we re-examine critically this suggestion in light of several recent works around the Maximum Entropy Production principle (MEP) that has been used in several out-of-equilibrium systems. We provide a set of four different optimization principles, based on maximization of energy dissipation, entropy production, Kolmogorov-Sinai entropy and minimization of mixing time, and study the connection between these principles using simple out-of-equilibrium models describing mixing of a scalar quantity. We find that there is a chained-relationship between most probable stationary states of the system, and their ability to obey one of the four principles. This provides an empirical justification of the Maximum Entropy Production principle in this class of systems, including some turbulent flows, for special boundary conditions. Otherwise, we claim that the minimization of the mixing time would be a more appropriate principle. We stress that this principle might actually be limited to flows where symmetry or dynamics impose pure mixing of a quantity (like angular momentum, momentum or temperature). The claim that turbulence is a state of maximum energy dissipation, a quantity intimately related to entropy production, is therefore limited to special situations that nevertheless include classical systems such as shear flows, Rayleigh-Benard convection and von Karman flows, forced with constant velocity or temperature conditions.
BibTeX:
@article{Mihelich2017,
  author = {M. Mihelich and D. Faranda and D. Paillard and B. Dubrulle},
  title = {Is Turbulence a State of Maximum Energy Dissipation?},
  journal = {Entropy},
  year = {2017},
  volume = {19},
  number = {4},
  doi = {10.3390/e19040154}
}
  • "Entropy Production in Field Theories without Time-Reversal Symmetry: Quantifying the Non-Equilibrium Character of Active Matter"
  • C. Nardini, E. Fodor, E. Tjhung, F. van Wijland, J. Tailleur and M. E. Cates
    Physical Review X. 7(2) (APR 18, 2017)
Abstract: Active-matter systems operate far from equilibrium because of the continuous energy injection at the scale of constituent particles. At larger scales, described by coarse-grained models, the global entropy production rate S quantifies the probability ratio of forward and reversed dynamics and hence the importance of irreversibility at such scales: It vanishes whenever the coarse-grained dynamics of the active system reduces to that of an effective equilibrium model. We evaluate S for a class of scalar stochastic field theories describing the coarse-grained density of self-propelled particles without alignment interactions, capturing such key phenomena as motility-induced phase separation. We show how the entropy production can be decomposed locally (in real space) or spectrally (in Fourier space), allowing detailed examination of the spatial structure and correlations that underly departures from equilibrium. For phase-separated systems, the local entropy production is concentrated mainly on interfaces, with a bulk contribution that tends to zero in the weak-noise limit. In homogeneous states, we find a generalized Harada-Sasa relation that directly expresses the entropy production in terms of the wave-vector-dependent deviation from the fluctuation-dissipation relation between response functions and correlators. We discuss extensions to the case where the particle density is coupled to a momentum-conserving solvent and to situations where the particle current, rather than the density, should be chosen as the dynamical field. We expect the New conceptual tools developed here to be broadly useful in the context of active matter, allowing one to distinguish when and where activity plays an essential role in the dynamics.
BibTeX:
@article{Nardini2017,
  author = {C. Nardini and E. Fodor and E. Tjhung and F. van Wijland and J. Tailleur and M. E. Cates},
  title = {Entropy Production in Field Theories without Time-Reversal Symmetry: Quantifying the Non-Equilibrium Character of Active Matter},
  journal = {Physical Review X},
  year = {2017},
  volume = {7},
  number = {2},
  doi = {10.1103/PhysRevX.7.021007}
}
Abstract: In this work, we present our first simulation results on the start-up, functioning and stopping (dry-out) of the multi-branch pulsating heat pipe (PHP) accounting for the fluid-tube thermal interaction and bubble generation (boiling). A theoretical model that generalizes an earlier proposed approach is described. It is shown that the account of tube heat conduction changes substantially the simulated PHP behavior. In particular, in the presence of tube heat conduction, the PHP cannot provide stable oscillations without bubble generation. While the bubble generation may not be directly involved in the development of first oscillations, its role is crucial in preventing the oscillations halt. The mechanism of the oscillation sustainment by bubble generation is discussed. The PHP simulation shows basic phenomena of bubble interaction and regimes observed experimentally in transparent PHPs. The PHP ceases functioning when the evaporator power is larger than a threshold. The liquid films are evaporated so the evaporator dries out completely and the oscillations stop; the evaporator temperature rises steeply. (C) 2017 Elsevier Ltd. All rights reserved.
BibTeX:
@article{Nekrashevych2017,
  author = {I. Nekrashevych and V. S. Nikolayev},
  title = {Effect of tube heat conduction on the pulsating heat pipe start-up},
  journal = {Applied Thermal Engineering},
  year = {2017},
  volume = {117},
  pages = {24-29},
  doi = {10.1016/j.applthermaleng.2017.02.013}
}
  • "Evaporation condensation-induced bubble motion after temperature gradient set-up"
  • V. S. Nikolayev, Y. Garrabos, C. Lecoutre, G. Pichavant, D. Chatain and D. Beysens
    Comptes Rendus Mecanique. 345(1):35-46 (JAN, 2017)
Abstract: Thermocapillary (Marangoni) motion of a gas bubble (or a liquid drop) under a temperature gradient can hardly be present in a one-component fluid. Indeed, in such a pure system, the vapor-liquid interface is always isothermal (at saturation temperature). However, evaporation on the hot side and condensation on the cold side can occur and displace the bubble. We have observed such a phenomenon in two different fluids submitted to a temperature gradient under reduced gravity: hydrogen under magnetic compensation of gravity in the HYLDE facility at CEA-Grenoble and water in the DECLIC facility onboard the ISS. The experiments and the subsequent analysis are performed in the vicinity of the vapor-liquid critical point to benefit from critical universality. In order to better understand the phenomena, a 1D numerical simulation has been performed. After the temperature gradient is imposed, two regimes can be evidenced. At early times, the temperatures in the bubble and the surrounding liquid become different thanks to their different compressibility and the "piston effect" mechanism, i.e. the fast adiabatic bulk thermalization induced by the expansion of the thermal boundary layers. The difference in local temperature gradients at the vapor-liquid interface results in an unbalanced evaporation/condensation phenomenon that makes the shape of the bubble vary and provoke its motion. At long times, a steady temperature gradient progressively formsin the liquid (but not in the bubble) and induces steady bubble motion towards the hot end. We evaluate the bubble velocity and compare with existing theories. (C) 2016 Academie des sciences. Published by Elsevier Masson SAS.
BibTeX:
@article{Nikolayev2017,
  author = {V. S. Nikolayev and Y. Garrabos and C. Lecoutre and G. Pichavant and D. Chatain and D. Beysens},
  title = {Evaporation condensation-induced bubble motion after temperature gradient set-up},
  journal = {Comptes Rendus Mecanique},
  year = {2017},
  volume = {345},
  number = {1},
  pages = {35-46},
  doi = {10.1016/j.crme.2016.10.002}
}
  • "Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria"
  • D. Nishiguchi, K. H. Nagai, H. Chate and M. Sano
    Physical Review E. 95(2) (FEB 7, 2017)
Abstract: We study the collective dynamics of elongated swimmers in a very thin fluid layer by devising long filamentous nontumbling bacteria. The strong confinement induces weak nematic alignment upon collision, which, for large enough density of cells, gives rise to global nematic order. This homogeneous but fluctuating phase, observed on the largest experimentally accessible scale of millimeters, exhibits the properties predicted by standard models for flocking, such as the Vicsek-style model of polar particles with nematic alignment: true long-range nematic order and nontrivial giant number fluctuations.
BibTeX:
@article{Nishiguchi2017,
  author = {D. Nishiguchi and K. H. Nagai and H. Chate and M. Sano},
  title = {Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria},
  journal = {Physical Review E},
  year = {2017},
  volume = {95},
  number = {2},
  doi = {10.1103/PhysRevE.95.020601}
}
  • "Chlorine in wadsleyite and ringwoodite: An experimental study"
  • M. Roberge, H. Bureau, N. Bolfan-Casanova, C. Raepsaet, S. Surble, H. Khodja, A.-L. Auzende, P. Cordier and G. Fiquet
    Earth and Planetary Science Letters. 467:99-107 (JUN 1, 2017)
Abstract: We report concentrations of Chlorine (Cl) in synthetic wadsleyite (Wd)and ringwoodite (Rw) in the system NaCl-(Mg,Fe)(2)SiO4 under hydrous and anhydrous conditions. Multi-anvil press experiments were performed under pressures (14-22 GPa) and temperatures (1100-1400 degrees C) relevant to the transition zone (TZ: 410-670 km depth). Cl and H contents were measured using Particle Induced X-ray Emission (PIXE) and Elastic Recoil Detection Analysis (ERDA) respectively. Results show that Cl content in Rw and Wd is significantly higher than in other nominally anhydrous minerals from the upper mantle (olivine, pyroxene, garnet), with up to 490 ppm Cl in anhydrous Rw, and from 174 to 200 ppm Cl in hydrous Wd and up to 113 ppm Cl in hydrous Rw. These results put constrains on the Cl budget of the deep Earth. Based on these results, we propose that the TZ may be a major repository for major halogen elements in the mantle, where Cl may be concentrated together with H2O and F (see Roberge et al., 2015). Assuming a continuous supply by subduction and a water-rich TZ, we use the concentrations measured in Wd (174 ppm Cl) and in Rw (106 ppm Cl) and we obtain a maximum value for the CI budget for the bulk silicate Earth (BSE) of 15.1 x 10(22) g Cl, equivalent to 37 ppm Cl. This value is larger than the 17 ppm Cl proposed previously by McDonough and Sun (1995) and evidences that the Cl content of the mantle may be higher than previously thought. Comparison of the present results with the budget calculated for F (Roberge et al., 2015) shows that while both elements abundances are probably underestimated for the bulk silicate Earth, their relative abundances are preserved. The BSE is too rich in F with respect to heavy halogen elements to be compatible with a primordial origin from chondrites Cl-like (carbonaceous chondrites CC) material only. We thus propose a combination of two processes to explain these relative abundances: a primordial contribution of different chondritic-like materials, including EC-like (enstatite chondrites), possibly followed by a distinct fractionation of F during the Earth differentiation due to its lithophile behavior compared to Cl, Br and l. (C) 2017 Elsevier B.V. All rights reserved.
BibTeX:
@article{Roberge2017,
  author = {M. Roberge and H. Bureau and N. Bolfan-Casanova and C. Raepsaet and S. Surble and H. Khodja and A.-L. Auzende and P. Cordier and G. Fiquet},
  title = {Chlorine in wadsleyite and ringwoodite: An experimental study},
  journal = {Earth and Planetary Science Letters},
  year = {2017},
  volume = {467},
  pages = {99-107},
  doi = {10.1016/j.epsl.2017.03.025}
}
  • "Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: linking the chemical composition to structural, physical and fracture properties"
  • C. L. Rountree
    Journal of Physics D: Applied Physics. 50:34 (2017)
BibTeX:
@article{Rountree2017,
  author = {C. L. Rountree},
  title = {Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: linking the chemical composition to structural, physical and fracture properties},
  journal = {Journal of Physics D: Applied Physics},
  year = {2017},
  volume = {50},
  pages = {34},
  url = {http://iopscience.iop.org/article/10.1088/1361-6463/aa7a8b/meta},
  doi = {10.1088/1361-6463/aa7a8b}
}
  • "Effects of turbulence, resistivity and boundary conditions on helicoidal flow collimation: Consequences for the Von-Karman-Sodium dynamo experiment"
  • J. Varela, S. Brun, B. Dubrulle and C. Nore
    Physics OF PLASMAS. 24(5) (MAY, 2017)
Abstract: We present hydrodynamic and magneto-hydrodynamic simulations of a liquid sodium flow using the compressible MHD code PLUTO to investigate the magnetic field regeneration in the Von-Karman-Sodium dynamo experiment. The aim of the study is to analyze the influence of the fluid resistivity and turbulence level on the collimation by helicoidal motions of a remnant magnetic field. We use a simplified Cartesian geometry to represent the flow dynamics in the vicinity of one cavity of a multi-blades impeller inspired by those used in the Von-Karman-Sodium (VKS) experiment. We perform numerical simulations with kinetic Reynolds numbers up to 1000 for magnetic Prandtl numbers between 30 and 0.1. Our study shows that perfect ferromagnetic walls favour enhanced collimation of flow and magnetic fields even if the turbulence degree of the model increases. More specifically, the location of the helicoidal coherent vortex in between the blades changes with the impinging velocity. It becomes closer to the upstream blade and the impeller base if the flow incident angle is analogous to the TM73 impeller configuration rotating in the unscooping direction. This result is also obtained at higher kinetic Reynolds numbers when the helicoidal vortex undergoes a precessing motion, leading to a reinforced effect in the vortex evolution and in the magnetic field collimation when using again perfect ferromagnetic boundary conditions. Configurations with different materials used for the impeller blades and the impeller base confirm a larger enhancement of the magnetic field when perfect ferromagnetic boundary conditions are used compared with the perfect conductor case, although smaller compared to a perfect ferromagnetic impeller, as it was observed in the VKS experiment. We further estimate the efficiency of a hypothetical dynamo loop occurring in the vicinity of the impeller and discuss the relevance of our findings in the context of mean field dynamo theory. Published by AIP Publishing.
BibTeX:
@article{Varela2017,
  author = {J. Varela and S. Brun and B. Dubrulle and C. Nore},
  title = {Effects of turbulence, resistivity and boundary conditions on helicoidal flow collimation: Consequences for the Von-Karman-Sodium dynamo experiment},
  journal = {Physics OF PLASMAS},
  year = {2017},
  volume = {24},
  number = {5},
  doi = {10.1063/1.4983313}
}
 

Other Publication Years:

2017, 2016, 2015, 2014, 2013, 2012, Older publications (2008-2011)

 

Maj : 03/08/2017 (2697)

 

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