3,593 research outputs found

    Antifungal effect and reduction of Ulmus minor symptoms to Ophiostoma novo-ulmi by carvacrol and salicylic acid

    Get PDF
    There are still no effective means to control Dutch elm disease (DED), caused by the vascular fungi Ophiostoma ulmi and O. novo-ulmi. Plant phenolics may provide a new strategy for DED control, given their known antifungal activity against pathogens and their involvement in plant defence mechanisms. The in vitro antifungal activity of salicylic acid, carvacrol, thymol, phenol, o-cresol, m-cresol, p-cresol, and 2,5-xylenol against the DED pathogens was tested. Also, the protective effect of watering Ulmus minor seedlings with these compounds was tested against O. novo-ulmi. Salicylic acid, carvacrol, and thymol showed the strongest antifungal in vitro activity, while carvacrol and salicylic acid provided the strongest in vivo protection against O. novo-ulmi (63 and 46% reduction of leaf wilting symptoms with respect to controls, respectively). The effect of the treatments on tree phenology was low, and a significant negative relation was observed between the number of days to bud burst and the leaf wilting symptoms after inoculation, probably determined by genetic differences among the elm tree progenies used. The treatments with salicylic acid, carvacrol and thymol induced the highest shift in phenolic metabolite profile with respect to control trees. The protective effect of carvacrol and salicylic acid is discussed in terms of their combined activity as antifungal compounds and as inductors of tree defence responses

    Fluvial sedimentation and its reservoir potential at foreland basin margins: A case study of the Puig-reig anticline (South-eastern Pyrenees)

    Get PDF
    Fluvial fans represent one of the dominant sedimentary systems at the active margins of non-marine foreland basins. The Puig-reig anticline at the north-eastern margin of the Ebro Foreland Basin (SE Pyrenees, Spain) exposes continuous outcrops of Late Eocene-Early Oligocene fluvial deposits, from proximal to medial fluvial fan environments. The proximal deposits are found in the north limb of the anticline, especially in the northwest zone. These deposits are characterised by conglomerates with minor interbedded sandstones, with thick and wide sheet-like geometries with unscoured or variably scoured basal surfaces. These are interpreted to be the deposits of unconfined flash floods and wide-shallow channel streams. The medial deposits, covering the rest of the anticline, consist of interbedded conglomerates, sandstones and claystones. These are interpreted to have been deposited from braided to meandering channel streams and overbank areas. Distal deposits are found towards the south, beyond the anticline, and are characterised by sandstone and clay deposits of terminal lobes and lacustrine deltas. This study assesses the impact of the primary depositional characteristics, diagenesis and deformation of the most heterolithic portion of the system, with implications for increasing our understanding of folded fluvial reservoirs. Diagenetic processes, mainly mechanical compaction and calcite cementation, resulted in overall low intergranular porosity, with limited relatively high porosity developed in sandstone lithofacies in the medial deposits. Deformation associated with thrusting and fold growth resulted in the formation of abundant fractures, with relatively high fracture intensities observed in sandstone lithofacies in the anticline crest. This study shows that post-depositional processes can both improve and diminish the reservoir potential of basin proximal fluvial deposits, through the development of fracture networks and by compaction-cementation. The comparison of the Puig-reig anticline with other similar settings worldwide indicates that foreland basin margin locations may be potential areas for effective reservoirs, even in the case of low intergranular porosity

    Streaky 3D Structures in the Boundary Layer

    Get PDF
    It has been recently shown [Choi, Nature, April 06 - Cossu, PRL, February 06] that 3D streaky structures in the boundary layer can remain laminar longer than the 2D Blasius °ow. The aim of this investigation is to study the possibility of promoting these 3D streaky structures via surface roughness, computing them and evaluat- ing the resulting stabilization using the Reduced Navier Stokes equations (RNS). The RNS are derived from Navier-Stokes making use of the fact that two very di®erent scales are present: one slow (streamwise direc- tion) and two short (spanwise and wall-normal direction). The RNS allows us to perform these 3D computations in a standard PC, without using CPU costly DNS simulations

    Computation of nonlinear streaky structures in boundary layer flow

    Get PDF
    In this work, the Reduced Navier Stokes (RNS) are numerically integrated, and used to calculate nonlinear finite amplitude streaks. These structures are interesting since they can have a stabilizing effect and delay the transition to the turbulent regime. RNS formulation is also used to compute the family of nonlinear intrinsic streaks that emerge from the leading edge in absence of any external perturbation. Finally, this formulation is generalized to include the possibility of having a curved bottom wal

    Molecular Dynamics Simulations of Couette flow

    Full text link
    The first steps towards developing a continuum-molecular coupled simulations techniques are presented, for the purpose of computing macroscopic systems of confined fluids. The idea is to compute the interface wall-fluid by Molecular Dynamics simulations, where Lennard-Jones potential (and others) have been employed for the molecular interactions, so the usual non slip boundary condition is not specified. Instead, a shear rate can be imposed at the wall, which allows to obtain the properties of the wall material by means of an iterative method. The remaining fluid region will be computed by a spectral hp method. We present MD simulations of a Couette flow, and the results of the developed boundary conditions from the wall fluid interaction

    Quenched disorder forbids discontinuous transitions in nonequilibrium low-dimensional systems

    Full text link
    Quenched disorder affects significantly the behavior of phase transitions. The Imry-Ma-Aizenman-Wehr-Berker argument prohibits first-order or discontinuous transitions and their concomitant phase coexistence in low-dimensional equilibrium systems in the presence of random fields. Instead, discontinuous transitions become rounded or even continuous once disorder is introduced. Here we show that phase coexistence and first-order phase transitions are also precluded in nonequilibrium low-dimensional systems with quenched disorder: discontinuous transitions in two-dimensional systems with absorbing states become continuous in the presence of quenched disorder. We also study the universal features of this disorder-induced criticality and find them to be compatible with the universality class of the directed percolation with quenched disorder. Thus, we conclude that first-order transitions do not exist in low-dimensional disordered systems, not even in genuinely nonequilibrium systems with absorbing states

    Nature s Top 100 Re-Revisited

    Full text link
    "This is the peer reviewed version of the following article: Martín-Martín, A., Ayllon, J. M., López-Cózar, E. D., & Orduna-Malea, E. (2015). Nature's top 100 Re-revisited. JASIST, 66(12), 2714., which has been published in final form at http://doi.org/10.1002/asi.23570. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."To mark the 50th anniversary of the Science Citation Index, Nature published a list of the 100 most-cited papers of all time. It also included an alternative ranking from data provided by Google Scholar, which, as this letter illustrates, contains certain inconsistencies. This does not, however, diminish the usefulness of Google Scholar, not only in identifying the most-cited articles of all time, but also in reflecting the impact of other document types (especially books), thus redefining the concept of academic impact. Keywords:Martín-Martín, A.; Ayllón, JM.; Delgado López-Cózar, E.; Orduña Malea, E. (2015). Nature s Top 100 Re-Revisited. Journal of the American Society for Information Science and Technology. 66(12):2714-2714. doi:10.1002/asi.23570271427146612Bornmann , L. Nature's top 100 revisited. Journal of the Association for Information Science and Technology http://www.lutz-bornmann.de/icons/top_100.pdfGarfield , E. 2005 The agony and the ecstasy-the history and meaning of the Journal Impact Factor http://www.garfield.library.upenn.edu/papers/jifchicago2005.pdfMartin-Martin , A. Orduna-Malea , E. Ayllon , J.M. Delgado Lopez-Cozar , E. 2014 Does Google Scholar contain all highly cited documents (1950-2013)? http://arxiv.org/abs/1410.8464Van Noorden, R., Maher, B., & Nuzzo, R. (2014). The top 100 papers. Nature, 514(7524), 550-553. doi:10.1038/514550

    Autoproblem : motor generador de problemes d'estadistica bàsica

    Get PDF
    Els objectius del projecte són: -Crear un conjunt d'aplicacions portables a qualsevol ordinador, per tal de que arribi al màxim d'usuaris possibles sigui quina sigui la seva situació geografica, si és a casa o si és a la facultat. D'aquesta manera es vol crear una aplicació que es pogués utilitiar com a material de classes de pràctiques, o com a material d'examen, o simplement perque l'estudiant pugui estudiar l'assignatura. - Creació d'un conjunt de rutines de simulació de dades aleatóries. D'aquesta manera estudiants que executen el mateix problema alhora tenen dades diferents, i per tant poden arribar a conclusions diferents. - La creació d'un programa d'edició de problemes senzill i fàcíl d'utilitzar per part del professor. - Crear una aplicació de resolució seqüencial i guiada deis problemes plantejats pel professor. Aquest és un dels objectius més importants, doncs es vol que l'estudiant resolgui el problema plantejat per l'aplicació de manera que posi en pràctica tot el que ha après a la classe i a més, que el resolgui d'una manera seqüencial. La creació d'un sistema de control deis estudiants que executin els problemes a la pàgina web. Aquest objectiu assolir aquest objectiu és important de cara a fer pràctiques o exàmens amb l'aplicació de l'estudiant. D'aquesta manera el professor pot conèixer l'evolució deIs seus estudiants al llarg del quadrimestres en que es faci l'assígnatura

    Short-term synaptic plasticity regulates the level of olivocochlear inhibition to auditory hair cells

    Get PDF
    In the mammalian inner ear, the gain control of auditory inputs is exerted by medial olivocochlear (MOC) neurons that innervate cochlear outer hair cells (OHCs). OHCs mechanically amplify the incoming sound waves by virtue of their electromotile properties while the MOC system reduces the gain of auditory inputs by inhibiting OHC function. How this process is orchestrated at the synaptic level remains unknown. In the present study, MOC firing was evoked by electrical stimulation in an isolated mouse cochlear preparation, while OHCs postsynaptic responses were monitored by whole-cell recordings. These recordings confirmed that electrically evoked IPSCs (eIPSCs) are mediated solely by α9β10 nAChRs functionally coupled to calcium-activated SK2 channels. Synaptic release occurred with low probability when MOC-OHC synapses were stimulated at 1 Hz. However, as the stimulation frequency was raised, the reliability of release increased due to presynaptic facilitation. In addition, the relatively slow decay of eIPSCs gave rise to temporal summation at stimulation frequencies >10 Hz. The combined effect of facilitation and summation resulted in a frequency-dependent increase in the average amplitude of inhibitory currents in OHCs. Thus, we have demonstrated that short-term plasticity is responsible for shaping MOC inhibition and, therefore, encodes the transfer function from efferent firing frequency to the gain of the cochlear amplifier.Fil: Ballestero, Jimena Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Zorrilla de San Martín, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Goutman, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Fuchs, Paul A.. The Johns Hopkins University School of Medicine; Estados UnidosFil: Katz, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentin
    corecore