5,673 research outputs found
Programming of inhomogeneous resonant guided wave networks
Photonic functions are programmed by designing the interference of local waves in inhomogeneous resonant guided wave networks composed of power-splitting elements arranged at the nodes of a nonuniform waveguide network. Using a compact, yet comprehensive, scattering matrix representation of the network, the desired photonic function is designed by fitting structural parameters according to an optimization procedure. This design scheme is demonstrated for plasmonic dichroic and trichroic routers in the infrared frequency range
Dynamical quenching and annealing in self-organization multiagent models
We study the dynamics of a generalized Minority Game (GMG) and of the Bar
Attendance Model (BAM) in which a number of agents self-organize to match an
attendance that is fixed externally as a control parameter. We compare the
usual dynamics used for the Minority Game with one for the BAM that makes a
better use of the available information. We study the asymptotic states reached
in both frameworks. We show that states that can be assimilated to either
thermodynamic equilibrium or quenched configurations can appear in both models,
but with different settings. We discuss the relevance of the parameter that
measures the value of the prize for winning in units of the fine for losing. We
also provide an annealing protocol by which the quenched configurations of the
GMG can progressively be modified to reach an asymptotic equlibrium state that
coincides with the one obtained with the BAM.Comment: around 20 pages, 10 figure
Negative refractive index in coaxial plasmon waveguides
We theoretically show that coaxial waveguides composed of a metallic core, surrounded by a dielectric cylinder and clad by a metal outer layer exhibit negative refractive index modes over a broad spectral range in the visible. For narrow dielectric gaps (10 nm GaP embedded in Ag) a figure-of-merit of 18 can be achieved at λ_0 = 460 nm. For larger dielectric gaps the negative index spectral range extends well below the surface plasmon resonance frequency. By fine-tuning the coaxial geometry the special case of n = −1 at a figure-of-merit of 5, or n = 0 for a decay length of 500 nm can be achieved
Plasmon Dispersion in Coaxial Waveguides from Single-Cavity Optical Transmission Measurements
We determine the plasmon dispersion relation in coaxial waveguides composed of a circular channel separating a metallic core and cladding. Optical transmission measurements are performed on isolated coaxial nanoapertures fabricated on a Ag film using focused ion-beam lithography. The dispersion depends strongly on the dielectric material and layer thickness. Our experimental results agree well with an analytical model for plasmon dispersion in coaxial waveguides. We observe large phase shifts at reflection from the end facets of the coaxial cavity, which strongly affect the waveguide resonances and can be tuned by changing the coax geometry, composition, and surrounding dielectric index, enabling coaxial cavities with ultrasmall mode volumes
Thermal treatment of the minority game
We study a cost function for the aggregate behavior of all the agents
involved in the Minority Game (MG) or the Bar Attendance Model (BAM). The cost
function allows to define a deterministic, synchronous dynamics that yields
results that have the main relevant features than those of the probabilistic,
sequential dynamics used for the MG or the BAM. We define a temperature through
a Langevin approach in terms of the fluctuations of the average attendance. We
prove that the cost function is an extensive quantity that can play the role of
an internal energy of the many agent system while the temperature so defined is
an intensive parameter. We compare the results of the thermal perturbation to
the deterministic dynamics and prove that they agree with those obtained with
the MG or BAM in the limit of very low temperature.Comment: 9 pages in PRE format, 6 figure
Efficient Coupling between Dielectric-Loaded Plasmonic and Silicon Photonic Waveguides
The realization of practical on-chip plasmonic devices will require efficient coupling of light into and out of surface plasmon waveguides over short length scales. In this letter, we report on low insertion loss for polymer-on-gold dielectric-loaded plasmonic waveguides end-coupled to silicon-on-insulator waveguides with a coupling efficiency of 79 ± 2% per transition at telecommunication wavelengths. Propagation loss is determined independently of insertion loss by measuring the transmission through plasmonic waveguides of varying length, and we find a characteristic surface-plasmon propagation length of 51 ± 4 μm at a free-space wavelength of λ = 1550 nm. We also demonstrate efficient coupling to whispering-gallery modes in plasmonic ring resonators with an average bending-loss-limited quality factor of 180 ± 8
Trophic ecology of the Endangered Darwin's frog inferred by stable isotopes
Indexación: Scopus.Acknowledgements. We thank Dr. Mauricio González-Chang for his contribution to invertebrate identification and Sally Wren for the revision of an earlier version of the manuscript. We are also extremely grateful to Tomás Elgueta Alvarez for providing Video S1. B.E.M.B. has a fellowship awarded by Universidad Andres Bello. This research project was approved by the Bioethics Committee at the Universi-dad Andres Bello, Chile (N°13/2015), and by permits N°5666/2013, N°230/2015, and N°212/2016 of the Chilean Agriculture and Livestock Service, and N°026/2013 and N°11/2015 IX of the Chilean National Forestry Corporation. This study was funded by the Dirección General de Investi-gación y Doctorados, Universidad Andres Bello, through grant N°DI-53-11/R and national funds through FONDE CYT N°11140902 and 1181758 (to C.S.A.).Darwin's frogs Rhinoderma spp. are the only known mouth-brooding frogs on Earth. The southern Darwin's frog, R. darwinii, is found in the temperate forests of southern South America, is listed as Endangered and could be the only extant representative of this genus. Based on stomach contents, invertebrate prey availability and stable isotope analysis, we determined for the first time trophic ecological parameters for this species. Our results showed that R. darwinii is a generalist sit-and-wait predator and a secondary consumer, with a trophic position of 2.9. Carbon and nitrogen isotope composition indicated that herbivore invertebrates are their main prey, detected in 68.1% of their assimilated food. The most consumed prey included mosquitoes, flies, crickets, grasshoppers and ants. Detritivore and carnivore invertebrates were also ingested, but in lower proportions. Our results contribute to a better understanding of the feeding habits of this fully terrestrial amphibian and provide the first insight into their role linking low forest trophic positions with intermediate predators. We provide valuable biological information for in situ and ex situ conservation which can be used when developing habitat protection, reintroduction and captive breeding programmes. As revealed here, stable isotope analysis is a valuable tool to study the trophic ecology of highly endangered and cryptic species. © The authors 2018.https://www.int-res.com/abstracts/esr/v36/p269-278
Experimental scheme for unambiguous discrimination of linearly independent symmetric states
We propose an optimal discrimination scheme for a case of four linearly
independent nonorthogonal symmetric quantum states, based on linear optics
only. The probability of discrimination is in agreement with the optimal
probability for unambiguous discrimination among N symmetric states [Phys.
Lett. A \textbf{250}, 223 (1998)]. The experimental setup can be extended for
the case of discrimination among nonorthogonal symmetric quantum states
Selling the Footlong Short: How Consumers Inch Toward Satisfaction in Costly Food Class Action Litigation
Food and beverage class action litigation has increased tremendously over the last five years. While many have ridiculed these lawsuits as ploys to extort money from wealthy food producers, plaintiff consumers maintain that the surge of food litigation suits evidence their growing desire for transparency. Many food-based class actions allege companies are purposefully deceiving consumers with misleading marketing campaigns. Defendants argue that a reasonable consumer should know better than to take their advertising at face value. Even still, defendants are often eager to resolve conflicts without admitting liability and, in turn, rush to settle the matter. Courts are then faced with such issues as class certification or whether to accept or reject a potential settlement. Even more challenging is determining whether a settlement provides a meaningful benefit to the entire class. When courts, however, determine that class members will receive only minor injunctive relief, while class counsel secures grand fee awards, settlements are often denied. Unfortunately, these decisions essentially leave potential plaintiffs without a viable alternative to recovery. Additionally, it allows food producers to continue with misleading marketing practices because consumers cannot hold them accountable
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