19 research outputs found
Glyceraldehyde-3-phosphate dehydrogenase is posttranslationally modified by NAD+ in enterohemorrhagic Escherichia coli
Comunicaciones a congreso
Breakdown transients in high-k multilayered MOS stacks: Role of the oxide-oxide thermal boundary resistance
In this work, breakdown transients of multilayered gate oxide stacks were analyzed to study the impact of the interfaces between oxides on the heat dissipation considering an electromigration-based progressive breakdown model. Using two distinct measurement setups on four different sets of samples, featuring two layers and three layers of Al 2 O 3 and HfO 2 interspersed, the breakdown transients were captured and characterized in terms of the degradation rate. Experimental results show that the number of oxide-oxide interfaces present in the multilayered stack has no visible impact on the breakdown growth rate among our samples. This strongly supports the interpretation of the bulk materials dominating the heat transfer to the surroundings of a fully formed conductive filament that shows no electrical differences between our various multilayered stack configurations.Fil: Boyeras Baldomá, Santiago. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Pazos, Sebastián MatÃas. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; ArgentinaFil: Aguirre, F. L.. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; ArgentinaFil: Palumbo, Felix Roberto Mario. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Separatrix splitting at a Hamiltonian bifurcation
We discuss the splitting of a separatrix in a generic unfolding of a
degenerate equilibrium in a Hamiltonian system with two degrees of freedom. We
assume that the unperturbed fixed point has two purely imaginary eigenvalues
and a double zero one. It is well known that an one-parametric unfolding of the
corresponding Hamiltonian can be described by an integrable normal form. The
normal form has a normally elliptic invariant manifold of dimension two. On
this manifold, the truncated normal form has a separatrix loop. This loop
shrinks to a point when the unfolding parameter vanishes. Unlike the normal
form, in the original system the stable and unstable trajectories of the
equilibrium do not coincide in general. The splitting of this loop is
exponentially small compared to the small parameter. This phenomenon implies
non-existence of single-round homoclinic orbits and divergence of series in the
normal form theory. We derive an asymptotic expression for the separatrix
splitting. We also discuss relations with behaviour of analytic continuation of
the system in a complex neighbourhood of the equilibrium
Continuation of the exponentially small transversality for the splitting of separatrices to a whiskered torus with silver ratio
We study the exponentially small splitting of invariant manifolds of
whiskered (hyperbolic) tori with two fast frequencies in nearly-integrable
Hamiltonian systems whose hyperbolic part is given by a pendulum. We consider a
torus whose frequency ratio is the silver number . We show
that the Poincar\'e-Melnikov method can be applied to establish the existence
of 4 transverse homoclinic orbits to the whiskered torus, and provide
asymptotic estimates for the tranversality of the splitting whose dependence on
the perturbation parameter satisfies a periodicity property. We
also prove the continuation of the transversality of the homoclinic orbits for
all the sufficiently small values of , generalizing the results
previously known for the golden number.Comment: 17 pages, 2 figure
Wear-out and breakdown of Ta2O5/Nb:SrTiO3 stacks
Tantalum oxide (Ta2O5) is widely used in electronics, with important applications in backend capacitors and memristors. However, major technological challenges have to be faced and solved. Also, concerns related to the reliability of these new stacks have to be taken into consideration. We report the reliability of Ta2O5 films focusing on the dynamics of the charge trapping and their leakage behavior under a constant voltage stress. We leverage the use of Nb:SrTiO3 back electrodes as a clean, well-defined surface, allowing the study of the Ta2O5 layer with no significant interface effects. The main features of the breakdown Ta2O5/Nb:SrTiO3 stacks are presented and analyzed in terms of an electromigration-based model. Our results outline the performance limits of Ta2O5 films, providing guidelines for development and integration of current and future devices.Fil: Boyeras Baldomá, Santiago. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; ArgentinaFil: Pazos, Sebastián MatÃas. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; ArgentinaFil: Aguirre, F. L.. Universitat Autònoma de Barcelona; EspañaFil: Ankonina, G.. Technion - Israel Institute of Technology; IsraelFil: Kornblum, L.. Technion - Israel Institute of Technology; IsraelFil: Yalon, E.. Technion - Israel Institute of Technology; IsraelFil: Palumbo, Felix Roberto Mario. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las IngenierÃas; Argentin
Anomalous out-of-equilibrium dynamics in the spin-ice material Dy<SUB>2</SUB>Ti<SUB>2</SUB>O<SUB>7</SUB> under moderate magnetic fields
We study experimentally and numerically the dynamics of the spin ice material Dy2Ti2O7 in the low temperature (T) and moderate magnetic field ( B ) regime (T ∈ [0.1, 1.7]  K, B ∈ [0, 0.3]  T). Our objective is to understand the main physics shaping the out-of-equilibrium magnetisation vs temperature curves in two different regimes. Very far from equilibrium, turning on the magnetic field after having cooled the system in zero field (ZFC) can increase the concentration of magnetic monopoles (localised thermal excitations present in these systems); this accelerates the dynamics. Similarly to electrolytes, this occurs through dissociation of bound monopole pairs. However, for spin ices the polarisation of the vacuum out of which the monopole pairs are created is a key factor shaping the magnetisation curves, with no analog. We observe a threshold field near 0.2 T for this fast dynamics to take place, linked to the maximum magnetic force between the attracting pairs. Surprisingly, within a regime of low temperatures and moderate fields, an extended Ohm's law can be used to describe the ZFC magnetisation curve obtained with the dipolar spin-ice model. However, in real samples the acceleration of the dynamics appears even sharper than in simulations, possibly due to the presence of avalanches. On the other hand, the effect of the field nearer equilibrium can be just the opposite to that at very low temperatures. Single crystals, as noted before for powders, abandon equilibrium at a blocking temperature T B which increases with field. Curiously, this behaviour is present in numerical simulations even within the nearest-neighbours interactions model. Simulations and experiments show that the increasing trend in T B is stronger for B ‖[100]. This suggests that the field plays a part in the dynamical arrest through monopole suppression, which is quite manifest for this field orientation.Instituto de FÃsica de LÃquidos y Sistemas Biológico