Random Walk Access Times on Partially-Disordered Complex Networks: an Effective Medium Theory

An analytic effective medium theory is constructed to study the mean access times for random walks on hybrid disordered structures formed by embedding complex networks into regular lattices, considering transition rates $F$ that are different for steps across lattice bonds from the rates $f$ across network shortcuts. The theory is developed for structures with arbitrary shortcut distributions and applied to a class of partially-disordered traversal enhanced networks in which shortcuts of fixed length are distributed randomly with finite probability. Numerical simulations are found to be in excellent agreement with predictions of the effective medium theory on all aspects addressed by the latter. Access times for random walks on these partially disordered structures are compared to those on small-world networks, which on average appear to provide the most effective means of decreasing access times uniformly across the network.Comment: 12 pages, 8 figures; added new results and discussion; added appendix on numerical procedures. To appear in PR

Analysis of the start to the first hurdle in 110m hurdles at the IAAF World Athletics Championships Beijing 2015

The purpose of this study was to use observational analysis to evaluate the relationships between variables measured at the start of the men’s 110 hurdles event and race performance itself. Data were obtained for competitors in 2015 IAAF World Athletics Ch ampionships, in Beijing, China. The athletes’ start was quantified by reaction time and time to the first hurdle; their action over the first hurdle was quantified by the take - off distance (i.e., the distance from the last step to the first hurdle), the la nding distance, and the total distance in the air over the first hurdle. Regression analyses revealed that the combination of one measure of the start (either reaction time or time to the first hurdle) and the measure of propulsion over the first hurdle (d istance in air over the first hurdle) predicted performance (SEE = 0.23 s in the heats, SEE = 0.16 s in the semi - finals, SEE = 0.09 s in the finals). In addition, looking at performances in the finals, where all athletes with available data used a seven - st ep approach to the first hurdle, inclusion of stride length data improved the prediction somewhat (SEE = 0.07 s). The results demonstrate that a combination of a fast start, rapid acceleration, and strong drive over the first hurdle quantifiably explains a nd contributes to performance in the men’s 110 m hurdles at the highest level

Rediscovery of the poorly known lichen-mantis Pogonogaster tristani Rehn, 1918 (MANTODEA: THESPIDAE, OLIGONICINAE) in Costa Rica and ecological notes

En el presente trabajo se divulga el redescubrimiento de la poco conocida mantisliquen Pogonogaster tristani Rehn, 1918 para una nueva localidad en Costa Rica, después de 96 años en ser descrita. Se incluyen notas relativas a la diagnosis de la especie, el conocimiento del macho, el hábitat natural y comportamiento.In this paper the rediscovery of the little known Lichen-Mantis Pogonogaster tristani Rehn, 1918 from a new location in Costa Rica, 96 years of being described, is published. Notes concerning the diagnosis of the species, knowledge of the male, the natural habitat and behavior are included

Desarrollo de un métode para identificación de guantes con policloruro de vinilo (pvc)

En un cuerpo hallado en una casa, en las cavidades de la oreja se encontraron ``motas'' plásticas provenientes de guantes de algodón moteados. Asimismo, se encontraron motas del mismo tipo en los alrededores del cuerpo. En la casa de un sospechoso, se encontraron guantes a los cuales les faltaban algunas motas. La pregunta es si podemos evaluar si los guantes hallados en la casa del sospechoso tienen un origen común con las motas encontradas en la escena del crimen. Se hizo un estudio comparativo de los diferentes tipos de PVC utilizados para hacer guantes moteados, utilizando diferentes guantes habituales en el mercado. Se evalúa la capacidad discriminatoria del análisis químico por la técnica de EDS (utilizando un SEM) y térmico con técnicas calorimétricas (DSC). Se analizan además las características morfológicas y cómo varían las texturas dependiendo del proceso de fabricación. Finalmente, se sugiere una secuencia de análisis para hacer la identificación del plástico, de manera de ir confirmando progresivamente la posibilidad de un origen común. La secuencia implica realizar estudios progresivamente más complejos. La utilidad de este esquema es poder detenerse a tiempo en el caso de que la incompatibilidad de las fuentes esté demostrada. Esto permite reducir costos y evitar la redundancia.In the ears of a corpse found in a house, were found PVC dots of the kind present in a common type of cotton gardening gloves. These dots were also found in the area surrounding the corpse. On the other hand, cotton gardening gloves whith some PVC dots missing were found at the house of a suspect. The question raised was whether it could be ascertained if the gloves found at the suspect's house had a common origin with the PVC dots found at the crime scene. A comparative study was made of different kinds of PVC used for manufacturing cotton gardening gloves, using different gloves available on the market. The discrimination capacity of the techniques used for chemical and thermal analysis, using EDS (with a SEM) and DSC, was analyzed. The morphological and texture characteristics depending on the fabrication process were also analyzed. An sequence of analyses is suggested for indentifying the plastics, in a way such that the common origin is progressively confirmed. The sequence implies the realization of studies of increasing complexity. The usefulness of this scheme is the feature it offers of stopping the tests in cases when the incompatibility of the samples has already been demonstrated. This reduces both costs and time spent on the analyses, avoiding redundant studies

Equivariant imaging: Learning beyond the range space

In various imaging problems, we only have access to compressed measurements of the underlying signals, hindering most learning-based strategies which usually require pairs of signals and associated measurements for training. Learning only from compressed measurements is impossible in general, as the compressed observations do not contain information outside the range of the forward sensing operator. We propose a new end-to-end self-supervised framework that overcomes this limitation by exploiting the equivariances present in natural signals. Our proposed learning strategy performs as well as fully supervised methods. Experiments demonstrate the potential of this framework on inverse problems including sparse-view X-ray computed tomography on real clinical data and image inpainting on natural images. Code will be released.Comment: Technical repor

Sensing Theorems for Unsupervised Learning in Linear Inverse Problems

International audienceSolving an ill-posed linear inverse problem requires knowledge about the underlying signal model. In many applications, this model is a priori unknown and has to be learned from data. However, it is impossible to learn the model using observations obtained via a single incomplete measurement operator, as there is no information about the signal model in the nullspace of the operator, resulting in a chicken-and-egg problem: to learn the model we need reconstructed signals, but to reconstruct the signals we need to know the model. Two ways to overcome this limitation are using multiple measurement operators or assuming that the signal model is invariant to a certain group action. In this paper, we present necessary and sufficient sensing conditions for learning the signal model from measurement data alone which only depend on the dimension of the model and the number of operators or properties of the group action that the model is invariant to. As our results are agnostic of the learning algorithm, they shed light into the fundamental limitations of learning from incomplete data and have implications in a wide range set of practical algorithms, such as dictionary learning, matrix completion and deep neural networks

Advertising regulation in the new consumer statute. Implications from the contract theory standpoint

En la contratación masiva contemporánea, el acercamiento entre los productores y/o proveedores de bienes y servicios y los consumidores se hace mayoritariamente a través de la publicidad. Dicha publicidad contiene elementos de información dirigidos al público, que pretenden modificar sus decisiones de consumo, por lo que se permite la inclusión de “elogios subjetivos del anunciante”. Frente a esta situación se plantean dos interrogantes: ¿lo que se dice en la publicidad vincula al anunciante? Y en caso de que la publicidad sea engañosa ¿qué consecuencias jurídicas se derivan de ello? Las respuestas a estos dos interrogantes varían según la naturaleza de la relación jurídica que exista entre las partes, la cual puede ser civil, mercantil o de consumo.In the contemporary mass hiring, the rapprochement between producers and/or suppliers of goods and services and the consumers is achieved mainly through advertising. This advertising has information elements aimed at the audience that intend to modify their consumption decisions, that is why the inclusion of “subjective compliments by the advertiser” is allowed. Two questions arise from this situation: does what is said in the advertisements bind the advertiser? And in the case the advertisements are actually misleading, what juridical consequences branch out from that? The answers to these two questions vary according to the nature of the juridical relation existing between the parties, which can be civil, commercial or of consumption

Tin oxide preparation and characterization and use as a catalyst in the reaction of unsaturated fatty esters epoxidation

La síntesis y la caracterización del óxido de estaño se estudiaron en este trabajo para evaluar su actividad catalítica en la reacción de epoxidación del metilricinoleato proveniente del aceite de ricino. La obtención del óxido se realiza por el método de precipitación controlada, encontrándose que se obtienen ventajas significativas al emplear soluciones acuosas de SnCl2.2H2O como precursor. Su caracterización se efectuó por medio de las técnicas de DTA, TGA, DRX, encontrándose que para obtener un alto rendimiento hacia el sistema casiterita el valor de pH óptimo fue de 6.25, mientras que un pH de 8.0 conlleva hacia el sistema romarchita. En el caso de las técnicas de MEB y área superficial, se determinó que el tamaño de partícula encontrado estaba por debajo de los 50 nm con un área superficial de 19 m2/g. El ester ricinoleico se obtuvo a partir del aceite empleando metilato de sodio como catalizador y seguidamente se hace reaccionar con peróxido de hidrógeno como agente oxidante y óxido de estaño para producir un epóxido. Finalmente, los productos de reacción se identifican por cromatografía de gases, encontrando que los óxidos de estaño son activos para la obtención de epóxidos con un mejor desempeño del sistema cristalino romarchita (SnO) principalmente hacia el metil-12-hidroxi-9,10-epoxioctadecanoato (MHEOD). Abstract Tin oxide synthesis and characterization were studied in the present work in order to evaluate its catalytic activity in the reaction of methyl ricinoleate from castor oil. Oxide is obtained through the controlled precipitation method, and significant advantages are obtained when using water solutions of SnCl2.2H2O as precursor. Its characterization was done using the techniques DTA, TGA, XRD, finding that in order to have high performance for the cassiterite system the optimum pH value was 6,25 whereas a pH of 8.0 was leading to the romarchite system. When using SEM techniques and a surface area, the size of the particle found was below 50 nm with a surface area of 19 m2/g. The ricinoleate ester was obtained from the oil using sodium methylate as catalyst and then making it react with hydrogen peroxide as oxidant agent and tin oxide to produce an epoxide. Finally, reaction products are identified through gas chromatography finding that tin oxides are active for obtaining epoxides with better performance of the romarchite crystal system (SnO) especially towards the methyl-12-hydroxi-9, 10-epoxioctadecanote (MHEOD)

A Sketching Framework for Reduced Data Transfer in Photon Counting Lidar

Single-photon lidar has become a prominent tool for depth imaging in recent years. At the core of the technique, the depth of a target is measured by constructing a histogram of time delays between emitted light pulses and detected photon arrivals. A major data processing bottleneck arises on the device when either the number of photons per pixel is large or the resolution of the time stamp is fine, as both the space requirement and the complexity of the image reconstruction algorithms scale with these parameters. We solve this limiting bottleneck of existing lidar techniques by sampling the characteristic function of the time of flight (ToF) model to build a compressive statistic, a so-called sketch of the time delay distribution, which is sufficient to infer the spatial distance and intensity of the object. The size of the sketch scales with the degrees of freedom of the ToF model (number of objects) and not, fundamentally, with the number of photons or the time stamp resolution. Moreover, the sketch is highly amenable for on-chip online processing. We show theoretically that the loss of information for compression is controlled and the mean squared error of the inference quickly converges towards the optimal Cram\'er-Rao bound (i.e. no loss of information) for modest sketch sizes. The proposed compressed single-photon lidar framework is tested and evaluated on real life datasets of complex scenes where it is shown that a compression rate of up-to 150 is achievable in practice without sacrificing the overall resolution of the reconstructed image.Comment: 16 pages, 20 figure

GBIF: mobilising information for adapting agriculture to climate change

Poster presented at Climate Change, Global Risk, Challenges & Decisions, Copenhagen (Denmark), 10-12 March 200