Exponential localization of singular vectors in spatiotemporal chaos

In a dynamical system the singular vector (SV) indicates which perturbation will exhibit maximal growth after a time interval $\tau$. We show that in systems with spatiotemporal chaos the SV exponentially localizes in space. Under a suitable transformation, the SV can be described in terms of the Kardar-Parisi-Zhang equation with periodic noise. A scaling argument allows us to deduce a universal power law $\tau^{-\gamma}$ for the localization of the SV. Moreover the same exponent $\gamma$ characterizes the finite-$\tau$ deviation of the Lyapunov exponent in excellent agreement with simulations. Our results may help improving existing forecasting techniques.Comment: 5 page

Logarithmic bred vectors in spatiotemporal chaos: structure and growth

Bred vectors are a type of finite perturbation used in prediction studies of atmospheric models that exhibit spatially extended chaos. We study the structure, spatial correlations, and the growth- rates of logarithmic bred vectors (which are constructed by using a given norm). We find that, after a suitable transformation, logarithmic bred vectors are roughly piecewise copies of the leading Lyapunov vector. This fact allows us to deduce a scaling law for the bred vector growth rate as a function of their amplitude. In addition, we relate growth rates with the spectrum of Lyapunov exponents corresponding to the most expanding directions. We illustrate our results with simulations of the Lorenz '96 model.Comment: 8 pages, 8 figure

European Critical Psychological trends: an open road to psychological recidivism

Depto. de Sociología: Metodología y TeoríaFac. de Ciencias Políticas y SociologíaTRUEpu

On the economic link between asset prices and real activity.

This paper presents a model linking two financial markets (stocks and bonds) with real business cycle, in the framework of the Consumption Capital Asset Pricing Model with Generalized Isoelastic Preferences. Besides interest rate term spread, the model includes a new variable to forecast economic activity: stock market term spread. This is the slope of expected stock market returns. The empirical evidence documented in this paper suggests systematic relationships between business cycle’s state and the shapes of two yield curves (interest rates and expected stock returns). Results are robust to changes in measures of economic growth, stock prices, interest rates and expectations generating mechanisms.Stock market; Interest rates; Economic growth; Term structure;

Characterization of electrical crosstalk in 4T-APS arrays using TCAD simulations

TCAD simulations have been conducted on a CMOS image sensor in order to characterize the electrical component of the crosstalk between pixels through the study of the electric field distribution. The image sensor consists on a linear array of five pinned photodiodes (PPD) with their transmission gates, floating diffusion and reset transistors. The effect of the variations of the thickness of the epitaxial layer has been addressed as well. In fact, the depth of the boundary of the epitaxial layer affects quantum efficiency (QE) so a correlation with crosstalk has been identified.Ministerio de Economía y Competitividad TEC2015-66878-C3-1RJunta de Andalucía TIC 2012-2338Office of Naval Research (USA) N00014141035

Continuous harmonic analysis and power quality measurements in three-phase systems

A virtual instrument, named Power Quality Meter, is presented for (a) measuring power consumption and harmonics in three-phase systems, under non-sinusoidal and imbalance conditions (b) detecting, classifying and organizes power disturbance events. Measurement of the power consumption follows the formulation proposed by the members of the IEEE Working Group on Nonsinusoidal Situations (1996). So, definitions are based on the analysis of functions in the frequency domain, separating the fundamental terms from the harmonic terms of the Fourier series. The virtual instrument has been developed too for monitoring and measuring power disturbances, which are automatically classified and organized in a database while they are being recorded. Software tools use the database structure to present summaries of power disturbances and locate an event by severity or time of occurrence. Records of actual measurements are included to demonstrate the versatility of the instrument

Potential of bacteriophage K as an antimicrobial strategy against biofilms of Staphylococcus aureus in the food industry

1 poster presented at the 24th International ICFMH Conference, Food Micro 2014, 1-4 Septembre, Nantes, FranceThe potential of phage K in the removal and prevention of Staphylococcus aureus biofilms on stainless steel surfaces was examined. The host range of the phage was tested on 18 strains from the food industry. Two out of six sensitive strains were selected for study of biofilms. Immature 6-h-old biofilms were challenged wfth a wide range of multipticlties of infection {MOl, 0.01-500) for 18 h at 25ºc. A noticeable effect on cell number was appreciated at MOIs≥10, but no effect was detected at lower MOis. Subsequently, 24 h-old biofilms (with a higher cell density and a more dense extracellular matrix) were challenged too at MOIs between 0.01-3.0 for 24 hat 25ºc. Again, a significant effect was only found at MOls > 1. The effectiveness in the prevention of biofilm formation was examined by Infecting planktonlc cultures of S. aureus with sub-lethal and lethal doses of phage K (MOIs 1-10-7-10.0). A notable effect on cell number and biofilm biomass was observed from MOIs >1·10-5. The potential of phage K as a tool for biohygienization in the food Industry acting specifically against biofilms of S. aureus was thus shown. However, neither biofilm cells were completely removed nor biofilm formation was totally prevented, and a sub-population of live cells was left In both cases As a result, the effectiveness of two co-adjuvant-based strategies was subsequently assessed. Combining DNase (0,1-10 mg/ml) with phage K (MOl of 0.3-3.0) did not show an additional effect on the removal of 24 h-old-biofilms at 25°C. A 30 min pre-treatment at 37ºc aimed to enhance DNase activity also had not effect. DNase did not show any effects by itself either. In contrast, combining cis-2-decenoic acid {1 - 100 nM) with phage K (MOl of 0.03-0.3) seemed to show some effects on biofilmsN

An Experimentally-Validated Verilog-A SPAD Model Extracted from TCAD Simulation

Single-photon avalanche diodes (SPAD) are photodetectors with exceptional characteristics. This paper proposes a new approach to model them in Verilog-A HDL with the help of a powerful tool: TCAD simulation. Besides, to the best of our knowledge, this is first model to incorporate a trap-assisted tunneling mechanism, a cross-section temperature dependence of the traps, and the self-heating effect. Comparison with experimental data establishes the validity of the model.Junta de Andalucía TIC 2012-2338Ministerio de Economía y Competitividad TEC2015-66878-C3-1-ROffice of Naval Research (USA) N00014141035

Traveling waves for a fisher-type reaction-diffusion equation with a flux in divergence form

Abstract. Analysis of the speed of propagation in parabolic operators is frequently carried out considering the minimal speed at which its traveling waves move. This value depends on the solution concept being considered. We analyze an extensive class of Fisher-type reaction-di usion equations with ows in divergence form. We work with regular ows, which may not meet the standard elliptical conditions, but without other types of singularities. We show that the range of speeds at which classic traveling waves move is an interval unbounded to the right. Contrary to classic examples, the in mum may not be reached. When the ow is elliptic or over-elliptic, the minimum speed of propagation is achieved. The classic traveling wave speed threshold is complemented by another value by analyzing an extension of the rst order boundary value problem to which the classic case is reduced. This singular minimum speed can be justi ed as a viscous limit of classic minimal speeds in elliptic or over-elliptic ows. We construct a singular pro le for each speed between the minimum singular speed and the speeds at which classic traveling waves move. Under additional assumptions, the constructed pro le can be justi ed as that of a traveling wave of the starting equation in the framework of bounded variation functions. We also show that saturated fronts verifying the Rankine-Hugoniot condition can appear for strictly lower speeds even in the framework of bounded variation functions.Spanish Government RTI2018-098850-B-I00Junta de Andalucia PY18-RT-2422 B-FQM-580-UGR20 A-FQM-311-UGR1