Slowing of pulses to c/10 with subwatt power levels and low latency using Brillouin amplification in a bismuth-oxide optical fiber

We report the generation of slow light using Brillouin amplification in a short length of highly nonlinear bismuth-oxide fiber. By using just 2m of fiber, we demonstrate a five-fold reduction in group velocity for ~200ns pulses, which we believe to be a record for a slow-light propagation in an optical fiber. Moreover, by virtue of the high nonlinearity per unit length of this fiber, we achieve this at a very modest pump power level of just ~400mW and with a low inherent device latency of 14ns. These results highlight both the merits and practicality of using high nonlinearity nonsilica fibers for slow-light devices

Relativistically covariant state-dependent cloning of photons

The influence of the relativistic covariance requirement on the optimality of the symmetric state-dependent 1 -> 2 cloning machine is studied. Namely, given a photonic qubit whose basis is formed from the momentum-helicity eigenstates, the change to the optimal cloning fidelity is calculated taking into account the Lorentz covariance unitarily represented by Wigner's little group. To pinpoint some of the interesting results, we found states for which the optimal fidelity of the cloning process drops to 2/3 which corresponds to the fidelity of the optimal classical cloner. Also, an implication for the security of the BB84 protocol is analyzed.Comment: corrected, rewritten and accepted in PR

Life-history traits in an evergreen Mediterranean oak respond differentially to previous experimental environments

Living organisms respond both to current and previous environments, which can have important consequences on population dynamics. However, there is little experimental evidence based on long-term field studies of the effects of previous environments on the performance of individuals. We tested the hypothesis that trees that establish under different environmental conditions perform differently under similar post-establishment conditions. We used the slow-growing, evergreen Mediterranean oak <i>Quercus ilex</i> subsp. <i>rotundifolia</i> as target species. We analyzed the effects of previous environments, competition effects and tradeoffs among life-history traits (survival, growth, and reproduction). We enhanced seedling establishment for three years by reducing abiotic environmental harshness by means of summer irrigation and artificial shading in 12 experimental plots, while four plots remained as controls. Then these treatments were interrupted for ten years. Seedlings under ameliorated environmental conditions survived and grew faster during early establishment. During the post-management period, previous treatments 1) did not have any effect on survival, 2) experienced a slower above-ground growth, 3) decreased root biomass as indicated from reflectivity of Ground Penetration Radar, 4) increased acorn production mostly through a greater canopy volume and 5) increased acorn production effort. The trees exhibited a combination of effects related to acclimation for coping with abiotic stress and effects of intra-specific competition. In accordance with our hypothesis, tree performance overall depended on previous environmental conditions, and the response was different for different life-history traits. We recommend early management because it increased plot cover, shortened the time to attain sexual maturity and increased the amount of acorn production. Plots such as those assessed in this study may act as sources of propagules in deforested agricultural landscapes thus aiding natural establishment of new plants

Planificación económica y autoritarismo en la “Revolución Argentina” (1966-1971)

Los regímenes autoritarios que se expandieron por América Latina en la década de 1960 estuvieron diseñados, según sus inspiradores, para resolver los dilemas que provenían de la conflictividad política, pero también de los estrangulamientos económicos que trababan el desarrollo nacional y regional. Este artículo investiga cómo la planificación fue instrumentada específicamente por el régimen de la “Revolución Argentina” como parte de su modelo de modernización autoritaria desde sus inicios mismos, en 1966. El Cordobazo mostró que el proyecto autoritario tenía bases más endebles de lo que suponían sus dirigentes. Esto determinó que se acentuara el sesgo planificador. Los planes de desarrollo fueron concebidos entonces como un mecanismo de acción pública de fuerte contenido tecnoburocrático, con la expectativa de que pudiera afianzarse un capitalismo nacional. Pero también fueron ideados como mecanismo de ampliación de la base social de apoyo, vis à vis la transición que se avecinaba

Rotational Effects of Twisted Light on Atoms Beyond the Paraxial Approximation

The transition probability for the emission of a Bessel photon by an atomic system is calculated within first order perturbation theory. We derive a closed expression for the electromagnetic potentials beyond the paraxial approximation that permits a systematic multipole approximation . The matrix elements between center of mass and internal states are evaluated for some specially relevant cases. This permits to clarify the feasibility of observing the rotational effects of twisted light on atoms predicted by the calculations. It is shown that the probability that the internal state of an atom acquires orbital angular momentum from light is, in general, maximum for an atom located at the axis of a Bessel mode. For a Gaussian packet, the relevant parameter is the ratio of the spread of the atomic center of mass wave packet to the transversal wavelength of the photon.Comment: 10 pages, no figure

Enciclopedia de arte: otra mirada para descubrir el mundo

La idea de escribir Mi primera enciclopedia de arte fue concebida por Diana Paris, directora y editora del proyecto, que convocó a distintas autoras para escribirla colectivamente. Además de la participación de las dos, la obra contó con la experiencia de la novelista Silvia Miguens y de la cuentista Teresita Romero. Mediante un cálido encuentro de café, comenzamos a soñar con una enciclopedia de arte infantil que fuera la primera entrada de los niños a ese mundo fascinante de la pintura. Pensamos en un libro que estuviera dirigido a chicos de 9 a 12 años, pero que también invitara al acompañamiento del adulto en esa lectura iniciática.Facultad de Humanidades y Ciencias de la Educació

Attachment and emotion regulation in substance addictions and behavioral addictions

Background Risky behaviors have been related to emotional regulation and attachment, which may constitute risk factors for developing an addictive behavior. However, there may also be differences between substance and non-substance-related addictions. Aims This study aimed to examine the relationship of emotional regulation and attachment, with substance (alcohol and drug abuse), and non-substance-related addictions (gambling disorder, video game addiction, and problematic Internet use) in adolescents and emerging adults. The study also aimed to examine gender differences for such predictors. Methods The sample comprised 472 students aged 13–21 years recruited from high schools and vocational education centers. Results Findings demonstrated that emotion regulation was predictive of all addictive behaviors assessed in this study (alcohol and drug abuse, gambling disorder, video game addiction, and problematic Internet use), whereas attachment predicted non-substance-related addictions (gambling disorder, video game addiction, and problematic Internet use). In addition, gender differences were found, with females scoring significantly higher in maternal and peer attachment, whereas males scored significantly higher in gambling disorder and video game addiction. Conclusion The findings may be useful for preventive and clinical interventions conducted with youth regarding addictive behaviors

All-optical 3D atomic loops generated with Bessel light fields

The propagation invariance of Bessel beams as well as their transversal structure are used to perform a comparative analysis of their effect on cold atoms for four different configurations and combinations thereof. We show that, even at temperatures for which the classical description of the atom center of mass motion is valid, the interchange of momentum, energy and orbital angular momentum between light and atoms yields efficient tools for all-optical trapping, transporting and, in general, manipulating the state of motion of cold atoms.Comment: 13 pages, 9 figure