Finite Size Effects in Separable Recurrent Neural Networks

We perform a systematic analytical study of finite size effects in separable recurrent neural network models with sequential dynamics, away from saturation. We find two types of finite size effects: thermal fluctuations, and disorder-induced `frozen' corrections to the mean-field laws. The finite size effects are described by equations that correspond to a time-dependent Ornstein-Uhlenbeck process. We show how the theory can be used to understand and quantify various finite size phenomena in recurrent neural networks, with and without detailed balance.Comment: 24 pages LaTex, with 4 postscript figures include

In-depth description of Electrohydrodynamic conduction pumping of dielectric liquids: physical model and regime analysis

In this work, we discuss the fundamental aspects of Electrohydrodynamic (EHD) conduction pumping of dielectric liquids. We build a mathematical model of conduction pumping that can be applied to all sizes, down to microsized pumps. In order to do this, we discuss the relevance of the Electrical Double Layer (EDL) that appears naturally on nonmetallic substrates. In the process, we identify a new dimensionless parameter related to the value of the zeta potential of the substrate-liquid pair, which quantifies the influence of these EDLs on the performance of the pump. This parameter also describes the transition from EHD conduction pumping to electro-osmosis. We also discuss in detail the two limiting working regimes in EHD conduction pumping: ohmic and saturation. We introduce a new dimensionless parameter, accounting for the electric field enhanced dissociation that, along with the conduction number, allows us to identify in which regime the pump operates.Ministerio de Ciencia, Innovación y Universidades PGC2018-099217-B-I0

On Limitations of the Ultrasonic Characterization of Pieces Manufactured with Highly Attenuating Materials

Some technical aspects of two Spanish cooperation projects, funded by DPI and Innpacto Programs of the R&D National Plan, are discussed. The objective is to analyze the common belief about than the ultrasonic testing in MHz range is not a tool utilizable to detect internal flaws in highly attenuating pieces made of coarse-grained steel. In fact high-strength steels, used in some safe industrial infrastructures of energy & transport sectors, are difficult to be inspected using the conventional “state of the art” in ultrasonic technology, due to their internal microstructures are very attenuating and coarse-grained. It is studied if this inspection difficulty could be overcome by finding intense interrogating pulses and advanced signal processing of the acquired echoes. A possible solution would depend on drastically improving signal-to-noise-ratios, by applying new advances on: ultrasonic transduction, HV electronics for intense pulsed driving of the testing probes, and an “ad-hoc” digital processing or focusing of the received noisy signals, in function of each material to be inspected. To attain this challenging aim on robust steel pieces would open the possibility of obtaining improvements in inspecting critical industrial components made of highly attenuating & dispersive materials, as new composites in aeronautic and motorway bridges, or new metallic alloys in nuclear area, where additional testing limitations often appear.The Spanish I+D National Plan (MINECO), by funding the Projects: Fundamental Research / DPI2011 – 22438, and INNPACTO Program / IMAAD - IPT-020000-2010-0004

Mechanical properties of freely suspended atomically thin dielectric layers of mica

We have studied the elastic deformation of freely suspended atomically thin sheets of muscovite mica, a widely used electrical insulator in its bulk form. Using an atomic force microscope, we carried out bending test experiments to determine the Young's modulus and the initial pre-tension of mica nanosheets with thicknesses ranging from 14 layers down to just one bilayer. We found that their Young's modulus is high (190 GPa), in agreement with the bulk value, which indicates that the exfoliation procedure employed to fabricate these nanolayers does not introduce a noticeable amount of defects. Additionally, ultrathin mica shows low pre-strain and can withstand reversible deformations up to tens of nanometers without breaking. The low pre-tension and high Young's modulus and breaking force found in these ultrathin mica layers demonstrates their prospective use as a complement for graphene in applications requiring flexible insulating materials or as reinforcement in nanocomposites.Comment: 9 pages, 5 figures, selected as cover of Nano Research, Volume 5, Number 8 (2012

Phase preserving amplification near the quantum limit with a Josephson Ring Modulator

Recent progress in solid state quantum information processing has stimulated the search for ultra-low-noise amplifiers and frequency converters in the microwave frequency range, which could attain the ultimate limit imposed by quantum mechanics. In this article, we report the first realization of an intrinsically phase-preserving, non-degenerate superconducting parametric amplifier, a so far missing component. It is based on the Josephson ring modulator, which consists of four junctions in a Wheatstone bridge configuration. The device symmetry greatly enhances the purity of the amplification process and simplifies both its operation and analysis. The measured characteristics of the amplifier in terms of gain and bandwidth are in good agreement with analytical predictions. Using a newly developed noise source, we also show that our device operates within a factor of three of the quantum limit. This development opens new applications in the area of quantum analog signal processing

Biochemical comparison of venoms from young Colombian Crotalus durissus cumanensis and their parents

Crotalus durissus cumanensis, a rattlesnake endemic to Colombia and Venezuela, is considered one of the most lethal snake species in Latin America. The aim of the present study was to compare the protein content and biological activity of the venom obtained from eight specimens of C. durissus cumanensis, namely two adults from different localities of Colombia and six offspring born in captivity. Protein profiles of crude venoms were analyzed by SDS-PAGE and RP-HPLC, and biological activities were evaluated for lethality, edema, defibrination, hemolytic and coagulant activities to assess individual venoms of adults and a pool of young snake venoms. Transient edema appeared rapidly after venom inoculation, whereas hemorrhagic effect was not observed. Differences in protein profiles, lethality, hemolytic, coagulant and defibrinating activities between both adult snake venoms were observed; those from the mother snake exhibited higher activities. Venoms from young snakes were similar to the one obtained from the mother, but the coagulant effect was stronger in offspring venoms. Notably, biological effects of the father snake venom were not comparable to those previously described for C. durissus cumanensis from Venezuela and C. durissus terrificus from Brazil, confirming the high variability of the venom from Crotalus species

Understanding atrioventricular septal defect: Anatomoechocardiographic correlation

<p>Abstract</p> <p>Objective</p> <p>Correlate the anatomic features of atrioventricular septal defect with echocardiographic images.</p> <p>Materials and methods</p> <p>Sixty specimen hearts were studied by sequential segmental analysis. Echocardiograms were performed on 34 patients. Specimen hearts with findings equivalent to those of echocardiographic images were selected in order to establish an anatomo-echocardiographic correlation.</p> <p>Results</p> <p>Thirty-three specimen hearts were in situs solitus, 19 showed dextroisomerism, 6 were in situs inversus and 2 levoisomerism. Fifty-eight had a common atrioventricular valve and 2 had two atrioventricular valves. Rastelli types were determined in 21 hearts. Nine were type A, 2 intermediate between A and B, 1 mixed between A and B, 4 type B and 5 type C. Associated anomalies included pulmonary stenosis, pulmonary atresia atrial septal defect, patent ductus arteriosus and anomalous connection of pulmonary veins. Echocardiograms revealed dextroisomerism in 12 patients, situs solitus in 11, levoisomerism in 7 and situs inversus in 4. Thirty-one patients had common atrioventricular valves and three two atrioventricular valves. Rastelli types were established in all cases with common atrioventricular valves; 17 had type A canal defects, 10 type B, 3 intermediate between A and B, 1 mixed between A and B and 3 type C. Associated anomalies included regurgitation of the atrioventricular valve, pulmonary stenosis, anomalous connection of pulmonary veins, pulmonary hypertension and pulmonary atresia.</p> <p>Conclusion</p> <p>Anatomo-echocardiographic correlation demonstrated a high degree of diagnostic precision with echocardiography.</p