Random global coupling induces synchronization and nontrivial collective behavior in networks of chaotic maps

The phenomena of synchronization and nontrivial collective behavior are studied in a model of coupled chaotic maps with random global coupling. The mean field of the system is coupled to a fraction of elements randomly chosen at any given time. It is shown that the reinjection of the mean field to a fraction of randomly selected elements can induce synchronization and nontrivial collective behavior in the system. The regions where these collective states emerge on the space of parameters of the system are calculated.Comment: 2 pages, 2 figs, accepted in The European Physical Journa

Non-Markovian Quantum Dynamics and Classical Chaos

We study the influence of a chaotic environment in the evolution of an open quantum system. We show that there is an inverse relation between chaos and non-Markovianity. In particular, we remark on the deep relation of the short time non-Markovian behavior with the revivals of the average fidelity amplitude-a fundamental quantity used to measure sensitivity to perturbations and to identify quantum chaos. The long time behavior is established as a finite size effect which vanishes for large enough environments.Comment: Closest to the published versio

Sampled Weighted Min-Hashing for Large-Scale Topic Mining

We present Sampled Weighted Min-Hashing (SWMH), a randomized approach to automatically mine topics from large-scale corpora. SWMH generates multiple random partitions of the corpus vocabulary based on term co-occurrence and agglomerates highly overlapping inter-partition cells to produce the mined topics. While other approaches define a topic as a probabilistic distribution over a vocabulary, SWMH topics are ordered subsets of such vocabulary. Interestingly, the topics mined by SWMH underlie themes from the corpus at different levels of granularity. We extensively evaluate the meaningfulness of the mined topics both qualitatively and quantitatively on the NIPS (1.7 K documents), 20 Newsgroups (20 K), Reuters (800 K) and Wikipedia (4 M) corpora. Additionally, we compare the quality of SWMH with Online LDA topics for document representation in classification.Comment: 10 pages, Proceedings of the Mexican Conference on Pattern Recognition 201

An Overview of the Coverage with ENC in the Mesoamerican Regional Hydrographic Commission and the Caribbean Sea - MACHC

Hydrographic offices worldwide started the production of Electronic Nautical Charts (ENCs) based on paper nautical charts, generating various designs in their schemes. The design of electronic nautical cartography schemes in the Regional Hydrographic Commissions (RHC) is analyzed, in order to understand the existence of schemes adopted by an entire region, or electronic nautical cartography schemes defined by countries with the capacity to produce them worldwide. The review allows us to know the state of the art in the regional schemes, methodologies and / or parameters used in their definition, and level of compliance with international regulations. In addition, questionnaires were carried out, which were used to acquire complementary information on hydrographic services, and this combined with the analyzes will determine the strengths and weaknesses in the current ENC coverage. Taking maritime safety into account, the investigations were conducive to presenting a methodological proposal for regional standardized ENC schemes. This article has been organized into five points, the first one presents the analysis of the coverage of current electronic charts, taking into account the metadata of the coverage used by the different Regional Hydrographic Commissions. In the second, a survey carried out to several Hydrographic Services is presented, including: the review and registration of relevant aspects of the ENC schemes at the RHCs level, as well as the socialization and issuance of the survey to the RENC Member States. IC-ENC; in the third, the results of the analysis of the information collected on the designs of the current ENC schemes in the RHCs that responded to the survey; the fourth presents the strengths and weaknesses found in specific cases of the current ENC schemes; and finally, in the fifth, the work in progress by the subgroup for the ENC Regional Scheme in the MACHC is evidenced.Los servicios hidrográficos de todo el mundo iniciaron la producción de Cartas Náuticas Electrónicas (ENCs) basadas en las cartas náuticas de papel, generando varios diseños de esquemas. Se analiza los diseños de esquemas de cartografía náutica electrónica en las Comisiones Hidrográficas Regionales (CHR) para conocer la existencia de esquemas adoptados por una región entera, o esquemas de cartografía náutica electrónica definidos por países con la capacidad para producirlos de manera global. Este estudio permite conocer los últimos avances en los esquemas regionales, las metodologías y/o parámetros utilizados en su definición y su nivel de cumplimiento de la normativa internacional. Además, se realizaron cuestionarios que se usaron para adquirir información complementaria sobre servicios hidrográficos, y esto combinado con los análisis determinará los puntos fuertes y débiles de la cobertura ENC actual. Teniendo en cuenta la seguridad marítima, las investigaciones fueron favorables a presentar una propuesta metodológica para esquemas ENC regionales normalizados. El artículo está organizado en cinco puntos, el primero presenta el análisis de la cobertura de las cartas electrónicas actuales, teniendo en cuenta los metadatos de la cobertura usada por las diferentes Comisiones Hidrográficas Regionales. En el segundo se presenta una encuesta realizada a varios Servicios Hidrográficos, incluyendo: revisión y registro de aspectos relevantes de los esquemas ENC al nivel de las CHRs, además de la socialización y remisión de la encuesta a los Estados Miembros del RENC IC-ENC; en el tercero, los resultados del análisis de la información recogida sobre los diseños de los esquemas ENC actuales en las CHRs que respondieron a la encuesta; el cuarto presenta los puntos fuertes y débiles encontrados en casos específicos de esquemas ENC actuales; y finalmente en el quinto se evidencia el trabajo en curso por el subgrupo para el Esquema Regional de ENC en la MACHC.Les Services hydrographiques du monde entier ont commencé à produire des cartes électroniques de navigation (ENC) à partir des cartes marines papier, générant ainsi divers modèles de schémas. La conception des schémas de cartes électroniques de navigation dans les Commissions hydrographiques régionales (CHR) est analysée, afin de connaître l'existence de schémas adoptés par une région entière, ou de schémas de cartes de navigation électroniques définis par des pays ayant la capacité de les produire dans le monde entier. Cette étude nous permet de connaître les dernières avancées des schémas régionaux, les méthodologies et/ou les paramètres utilisés dans leur définition, et leur niveau de conformité avec les réglementations internationales. En outre, des questionnaires ont été réalisés et ont permis d'obtenir des informations complémentaires sur les services hydrographiques, ce qui, combiné aux analyses, permettra de déterminer les forces et les faiblesses de la couverture actuelle en ENC. En tenant compte de la sécurité maritime, les investigations ont permis de présenter une proposition méthodologique pour des schémas ENC régionaux normalisés. Cet article s'articule autour de cinq points : le premier point présente l'analyse de la couverture des cartes électroniques actuelles, en tenant compte des métadonnées de couverture utilisées par les différentes Commissions hydrographiques régionales. Au second point, une enquête réalisée auprès de plusieurs Services hydrographiques est présentée, comprenant : l'examen et l'enregistrement des aspects pertinents des schémas ENC au niveau des CHR, ainsi que la socialisation et la diffusion de l’enquête auprès des Etats membres du RENC IC-ENC ; au troisième point, les résultats de l'analyse des informations recueillies sur la conception des schémas ENC actuels dans les CHR qui ont répondu à l’enquête ; le quatrième point présente les forces et les faiblesses constatées dans des cas spécifiques de schémas ENC actuels ; et enfin le cinquième point met en évidence le travail en cours du sous-groupe pour le schéma régional d'ENC au sein de la CHMAC

Mapping deuterated methanol toward L1544: I. Deuterium fraction and comparison with modeling

The study of deuteration in pre-stellar cores is important to understand the physical and chemical initial conditions in the process of star formation. In particular, observations toward pre-stellar cores of methanol and deuterated methanol, solely formed on the surface of dust grains, may provide useful insights on surface processes at low temperatures. Here we analyze maps of CO, methanol, formaldehyde and their deuterated isotopologues toward a well-known pre-stellar core. This study allows us to test current gas-dust chemical models. Single-dish observations of CH$_3$OH, CH$_2$DOH, H$_2$CO, H_2\,^{13}CO, HDCO, D$_2$CO and C$^{17}$O toward the prototypical pre-stellar core L1544 were performed at the IRAM 30 m telescope. We analyze their column densities, distributions, and compare these observations with gas-grain chemical models. The maximum deuterium fraction derived for methanol is [CH$_2$DOH]/[CH$_3$OH] $\sim$ 0.08$\pm$0.02, while the measured deuterium fractions of formaldehyde at the dust peak are [HDCO]/[H$_2$CO] $\sim$ 0.03$\pm$0.02, [D$_2$CO]/[H$_2$CO] $\sim$ 0.04$\pm$0.03 and [D$_2$CO]/[HDCO] $\sim$ 1.2$\pm$0.3. Observations differ significantly from the predictions of models, finding discrepancies between a factor of 10 and a factor of 100 in most cases. It is clear though that to efficiently produce methanol on the surface of dust grains, quantum tunneling diffusion of H atoms must be switched on. It also appears that the currently adopted reactive desorption efficiency of methanol is overestimated and/or that abstraction reactions play an important role. More laboratory work is needed to shed light on the chemistry of methanol, an important precursor of complex organic molecules in space.Comment: Accepted for publication in A&

Filter tuning system using fuzzy logic

The authors describe an expert system approach for tuning filters using fuzzy logic. The proposed system adjusts the filter components in order to meet the given window specifications. The system is described and experimental results are presented for a lowpass filter implemented with OTA

Techniques in Analytic Lamb Shift Calculations

Quantum electrodynamics has been the first theory to emerge from the ideas of regularization and renormalization, and the coupling of the fermions to the virtual excitations of the electromagnetic field. Today, bound-state quantum electrodynamics provides us with accurate theoretical predictions for the transition energies relevant to simple atomic systems, and steady theoretical progress relies on advances in calculational techniques, as well as numerical algorithms. In this brief review, we discuss one particular aspect connected with the recent progress: the evaluation of relativistic corrections to the one-loop bound-state self-energy in a hydrogenlike ion of low nuclear charge number, for excited non-S states, up to the order of alpha (Zalpha)^6 in units of the electron mass. A few details of calculations formerly reported in the literature are discussed, and results for 6F, 7F, 6G and 7G states are given.Comment: 16 pages, LaTe