202,058 research outputs found
A Prony-Based Approach for Accelerating the Lightning Electromagnetic Fields Computation: Effect of the Soil Finite Conductivity
No full textThis work provides an approach for speeding up the evaluation of lightning ElectroMagnetic (EM) fields in the case of a finite soil conductivity. The soil conductivity is taken into account through the well-known Cooray-Rubinstein (CR) approximation, which corrects the radial term of the electric field. A comparative analysis with some of the existing methods reveals an excellent accuracy with a substantial improvement in the CPU performance.SCI-STI-F
Analytical expressions for lightning electromagnetic fields with arbitrary channel-base current-Part I: Theory
No full textThe article provides analytical expressions for the electromagnetic fields generated by a lightning return stroke characterized by a channel-base current with arbitrary time waveform, in presence of either a perfectly conducting or a lossy ground, assuming the transmission line model for the current along the channel. In this second case, a time-domain analytical expression for the Cooray-Rubinstein formula is presented. The main idea that leads to the derivation of analytical formulas consists of dividing the channel into intervals in which the distance between the field source point and the observation point can be approximated with a linear function of the time, and of the spatial coordinates of both points. In the companion aticle, a detailed comparison is proposed with the classical (numerical) approach highlighting an excellent agreement both at close and far distances, considering all the values of practical interest for the ground conductivity. Moreover, the method guarantees a meaningful improvement in computational performance
Anton Rubinstein
No full textRetrat primer pla d'Anton Rubinstein; amb dedicatòria datada a Paris el 10 de març de 188
CREBBP mutations in individuals without Rubinstein–Taybi syndrome phenotype
No full textMutations in CREBBP cause Rubinstein–Taybi syndrome. By using exome sequencing, and by using Sanger in one patient, CREBBP mutations were detected in 11 patients who did not, or only in a very limited manner, resemble Rubinstein–Taybi syndrome. The combined facial signs typical for Rubinstein–Taybi syndrome were absent, none had broad thumbs, and three had only somewhat broad halluces. All had apparent developmental delay (being the reason for molecular analysis); five had short stature and seven had microcephaly. The facial characteristics were variable; main characteristics were short palpebral fissures, telecanthi, depressed nasal ridge, short nose, anteverted nares, short columella, and long philtrum. Six patients had autistic behavior, and two had self-injurious behavior. Other symptoms were recurrent upper airway infections (n = 5), feeding problems (n = 7) and impaired hearing (n = 7). Major malformations occurred infrequently. All patients had a de novo missense mutation in the last part of exon 30 or beginning of exon 31 of CREBBP, between base pairs 5,128 and 5,614 (codons 1,710 and 1,872). No missense or truncating mutations in this region have been described to be associated with the classical Rubinstein–Taybi syndrome phenotype. No functional studies have (yet) been performed, but we hypothesize that the mutations disturb protein–protein interactions by altering zinc finger function. We conclude that patients with missense mutations in this specific CREBBP region show a phenotype that differs substantially from that in patients with Rubinstein–Taybi syndrome, and may prove to constitute one (or more) separate entities. © 2016 Wiley Periodicals, Inc
A review of the modeling approaches of the lightning M-component with special attention to their current and electric field characteristics
No full textIn this paper, we present the characteristics of current, electric fields and modeling approaches of lightning M -component mode of charge transfer. We consider both the classical M-components (occurring after return strokes) and M-component-type ICC (Initial Continuous Current) pulses occurring during the initial (ICC) phase of upward flashes. M-component-type ICC pulses can be distinguished from mixed-mode pulses using different criteria: (i) the 10-90% current risetime at the channel-base with respect to an 8-mu s risetime; (ii) the time lag between the onset of the current and electric fields with a respect to a threshold of 10 mu s; (iii) an asymmetrical waveform coefficient (AsWc) with respect to a value of 0.8; (iv) the relative height of the junction or connection points on the grounded channel above the ground. The features of M-component electric field waveforms are summarized for close, intermediate, and far distance ranges. The observed millisecond-scale slow-part pulse shows a polarity reversal from an initial-negative waveform at close range, to a full positive-flattening late-time response at intermediate range and a bipolar wave-shape at the far distance range. One or some microsecond -scale fast pulses (junction pulse) are observed to precede the millisecond-scale slow part pulse at intermediate and far distance ranges. The microsecond-scale fast pulses are dominated by unipolar pulses along with several cases of bipolar pulses exhibiting initial polarities of both signs. The main advantage of the guided wave model and its variations is their simplicity and straightforward implementation. The guided wave model is also able to reproduce reasonably well the observed slow electric fields. The nonlinear models are more physics-based compared to the guided wave models. They are based on an important number of adjustable parameters, many of which cannot be directly inferred from experimental observations. The significance of M-components is reviewed according to practical aspects in transformer secondary, surge protective devices (SPD), grounding systems
Trading Partners and Trading Volumes: Implementing the Helpman-Melitz-Rubinstein Model Empirically
No full textHelpman, Melitz, and Rubinstein (2008)-HMR-present a rich theoretical model to study the determinants of bilateral trade flows across countries. The model is then empirically implemented through a two-stage estimation procedure. This note seeks to clarify some econometric aspects of the estimation approach used by HMR and explore the consequences of possible departures from the maintained distributional assumptions.Gravity equation, Heteroskedasticity, Jensens inequality
On risk aversion in the Rubinstein bargaining game
No full textWe derive closed-form solutions for the Rubinstein alternating offers game for cases where the two players have (possibly asymmetric) utility functions that belong to the HARA class and discount the future at a constant rate. We show that risk aversion may increase a bargainers payoff. This result - which contradicts Roth’s 1985 theorem tying greater risk neutrality to a smaller payoff - does not rely on imperfect information or departures from expected utility maximization
On Risk Aversion in the Rubinstein Bargaining Game
No full textWe derive closed-form solutions for the Rubinstein alternating offers game for cases where the two players have (possibly asymmetric) utility functions that belong to the HARA class and discount the future at a constant rate. We show that risk aversion may increase a bargainers payoff. This result - which contradicts Roth’s 1985 theorem tying greater risk neutrality to a smaller payoff - does not rely on imperfect information or departures from expected utility maximization.
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