Mobile termination and mobile penetration

In this paper, we study how access pricing affects network competition when subscription demand is elastic and each network uses non-linear prices and can apply termination-based price discrimination. In the case of a fixed per minute termination charge, we find that a reduction of the termination charge below cost has two opposing effects: it softens competition but helps to internalize network externalities. The former reduces mobile penetration while the latter boosts it. We find that firms always prefer termination charge below cost for either motive while the regulator prefers termination below cost only when this boosts penetration. Next, we consider the retail benchmarking approach (Jeon and Hurkens, 2008) that determines termination charges as a function of retail prices and show that this approach allows the regulator to increase penetration without distorting call volumes.

Calling vs receiving party pays: market penetration and the importance of the call externality

In this paper we study how the access price affects the choice of the tariff regime taken by the network operators. We show that for high values of the access price, that is taken as a parameter by the firms, networks decide to charge only the callers. Otherwise, for low values of the access charge, networks charge also the receivers. Moreover, we compare market penetration and total welfare between the two price regimes. Our model suggests that, for high values of call externality, market penetration and total welfare are larger in Receiving Party Pays regime when the access charge is close to zero.

Mobile termination and mobile penetration

In this paper, we study how access pricing affects network competition when subscription demand is elastic and each network uses non-linear prices and can applytermination-based price discrimination. In the case of a fixed per minute terminationcharge, we find that a reduction of the termination charge below cost has two opposing effects: it softens competition but helps to internalize network externalities. Theformer reduces mobile penetration while the latter boosts it. We find that firms always prefer termination charge below cost for either motive while the regulator preferstermination below cost only when this boosts penetration.Next, we consider the retail benchmarking approach (Jeon and Hurkens, 2008)that determines termination charges as a function of retail prices and show that thisapproach allows the regulator to increase penetration without distorting call volumes.

Intensity correlation function of dye lasers: Short-time behavior

We propose an equation to calculate the intensity correlation function of a dye-laser model with a pump parameter subject to finite-bandwidth fluctuations. The equation is valid, in the weak-noise limit, for all times. It incorporates novel non-Markovian features. Results are given for the short-time behavior of the correlation function. It exhibits a characteristic initial plateau. Our findings are supported by a numerical simulation of the model.

Theory for the transient statistics of a dye laser

A theory is presented to explain the statistical properties of the growth of dye-laser radiation. Results are in agreement with recent experimental findings. The different roles of pump-noise intensity and correlation time are elucidated.

Intensity correlation functions of dye lasers: Comparison of colored-gain-noise and colored-loss-noise models

The intensity correlation functions C(t) for the colored-gain-noise model of dye lasers are analyzed and compared with those for the loss-noise model. For correlation times ¿ larger than the deterministic relaxation time td, we show with the use of the adiabatic approximation that C(t) values coincide for both models. For small correlation times we use a method that provides explicit expressions of non-Markovian correlation functions, approximating simultaneously short- and long-time behaviors. Comparison with numerical simulations shows excellent results simultaneously for short- and long-time regimes. It is found that, when the correlation time of the noise increases, differences between the gain- and loss-noise models tend to disappear. The decay of C(t) for both models can be described by a time scale that approaches the deterministic relaxation time. However, in contrast with the loss-noise model, a secondary time scale remains for large times for the gain-noise model, which could allow one to distinguish between both models.

Comment on: Deuterium nuclear fusion at room temperature: A pertinent inequality on barrier penetration

In a recent letter, Rosen claims to justify ...

Avalanche-like vortex penetration driven by pulsed microwave fields in an epitaxial LaSrCuO thin film

Different vortex penetration regimes have been registered in the output voltage signal of a magnetometer when single microwave pulses are applied to an epitaxial overdoped La2− x Sr x CuO4 thin film in a perpendicular dc magnetic field. The onset of a significant variation in the sample magnetization which exists below threshold values of temperature, dc magnetic field, and pulse duration is interpreted as an avalanche-type flux penetration. The microwave contribution to the background electric field suggests that the nucleation of this fast vortex motion is of electric origin, which also guarantees the occurrence of vortex instabilities under adiabatic conditions via the enhancement of the flux flow resistivity. Flux creep phenomena and heat transfer effects act as stabilizing factors against the microwave-pulse-induced fast flux diffusion.

¿Qué entienden los jóvenes universitarios por monogamia y sexo sin penetración, como estrategias preventivas de la transmisión sexual del virus del SIDA? = What university students understand by monogamy and sex without penetration as preventive strategies of sexual transmission of AIDS virus?

Monogamy and sex without penetration are behaviors recommended by the WHO to avoid AIDS virus sexual transmission. Seven hundred and fifty university students from 18 to 25 years (67.7% women) were surveyed and they were asked to give a maximum of three free definitions of the words monogamy and sex without penetration to prevent AIDS virus sexual transmission. Their participation was voluntary and anonymous. Although the majority of the answers was correct, there was a considerable percentage of wrong answers, either for monogamy (3.7% masturbation; 2.1% to have many partners; 0.9% homosexual relations), or for sex without penetration (20.5% oral sex; 1.1% anal coitus; 0.8% coitus without orgasm; 0.4% coitus interruptus). Some definitions or examples differ by gender. The amount of wrongs or incomplete answers put researchers on the alert about insufficient preventive knowledge in a population with a high educational level

Empleo de óptica adaptativa y fluorescencia en un oftalmoscopio laser de barrido para el registro de células

Estudio elaborado a partir de una estancia en la Universidad de Rochester, Estados Unidos, de octubre del 2006 a enero del 2007. La estancia realizada en la Universidad de Rochester estuvo orientada al aprendizaje en profundidad del oftalmoscopio láser de barrido. El oftalmoscopio láser de barrido emplea una técnica confocal con la finalidad de visualizar diferentes estructuras retinianas en seres vivos. El instrumento diseñado y desarrollado en el Centro de Ciencias de la Visión incorpora un sistema de óptica adaptativa y fluorescencia. La óptica adaptativa aplicada en este oftalmoscopio tiene como objetivo corregir las aberraciones existentes en el ojo y así permitir observar detalles de la retina que de otra forma se verían emborronados. De esta forma se consigue alcanzar valores de resolución muy cercanos a los impuestos por difracción. Por otro lado el uso de fluorescencia tiene por objetivo el permitir la visualización de células y estructuras que, de no ser teñidas, son transparentes a la luz y visible. Esta técnica se ha estado utilizando principalmente en primates y ratas, aunque actualmente también se están llevando a cabo medidas de células de epitelio pigmentario en seres humanos ya que el pigmento contenido en estas células permite la aplicación de la fluorescencia sin necesidad de utilizar tinción.

North-South trade and directed technical change

In a world where poor countries provide weak protection for intellectual property rights (IPRs), market integration shifts technical change in favor of rich nations. Through this channel, free trade may amplify international income differences. At the same time, integration with countries where IPRs are weakly protected can slow down the world growth rate. An important implication of these results is that protection of intellectual property is most beneficial in open countries. This prediction, which is novel in the literature, is consistent with evidence from a panel of 53 countries observed in the years 1965-1990. The paper also provides empirical support for the mechanism linking North-South trade to the direction of technical change: an increase in import penetration from low-wage, low-IPRs, countries is followed by a sharp fall in R&D investment in a panel of US manufacturing sectors.