9,736 research outputs found

    Three Hopf algebras from number theory, physics & topology, and their common background II: general categorical formulation

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    We consider three a priori totally different setups for Hopf algebras from number theory, mathematical physics and algebraic topology. These are the Hopf algebra of Goncharov for multiple zeta values, that of Connes-Kreimer for renormalization, and a Hopf algebra constructed by Baues to study double loop spaces. We show that these examples can be successively unified by considering simplicial objects, co-operads with multiplication and Feynman categories at the ultimate level. These considerations open the door to new constructions and reinterpretations of known constructions in a large common framework which is presented step-by-step with examples throughout. In this second part of two papers, we give the general categorical formulation

    Syntaxonomic conspectus of the vegetation of Catalonia and Andorra. I: Hygrophilous herbaceous communities.

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    The first part of a general survey of the vegetation of Catalonia and Andorra, this paper reports all the phytocoenological associations and subassociations recorded in this area. For each community, we provide the correct name and usual synonyms, its typification (where appropriate), all the references including relevés, and the most outstanding features of its structure, species composition, ecology, distribution and diversity. Moreover, associations and subassociations are ordered appropriately in a syntaxonomic scheme. Syntaxonomic ranks are considered in a fairly broad, conservative sense. This classification established 101 associations, which correspond to the classes Lemnetea, Zosteretea, Potametea, Littorelletea, Montio-Cardaminetea, Phragmiti-Magnocaricetea, Scheuchzerio-Caricetea, Isoeto-Nanojuncetea and Molinio-Arrhenatheretea

    Fascioliasis in confiscated livers of cattle in the Municipal Refrigerated Camal of Ambato and its relationship with Food Safety

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    Fascioliasis is a parasitic disease of herbivorous animals, especially the bovine and zoonotic species. It was proposed to analyze the number of cases through a retrospective study on the prevalence of seized livers due to the presence of the Fasciola hepatica parasite in the Municipal Cold Store of Ambato, province of Tungurahua belonging to the Sierra region with a temperate climate located in Ecuador, since the years 2016 to 2021 the first six months in this last year. The collection and analysis of the information was carried out between the months of January to August 2021. The methodology used was descriptive and through a bibliographic review of scientific and observational articles to help in the macroscopic determination of the parasite in cattle livers. that came to be slaughtered in the years already mentioned in this study. The total population of slaughtered bovines was taken; which were 110,867 in the six years of study, this number decreased due to restrictions of the COVID-19 pandemic between 2020 and 2021. The prevalence of fascioliasis was analyzed for all study years, with an average of 7.27%, of this In this way, the presence of Fascioliasis in the Municipal Cold Store of Ambato-Ecuador is demonstrated; A plan is recommended on the management, prevention, control, treatment and eradication of said parasite and to make the population aware of the risk factors when consuming contaminated foods such as livers, watercress, vegetables and water contaminated with larvae. Keywords: Fasciola Hepatica, fascioliasis, safety, food, livers, confiscated. Resumen La Fascioliasis es una enfermedad parasitaria de los animales herbívoros, en especial de la especie bovina y zoonótica. Se planteó analizar el número de casos mediante un estudio retrospectivo sobre la prevalencia de hígados decomisados por la presencia del parásito Fasciola hepatica en el Camal Frigorífico Municipal de Ambato, provincia de Tungurahua perteneciente a la región Sierra con clima templado ubicado en Ecuador, desde los años 2016 al 2021 los primeros seis meses en este último año. La recopilación y análisis de la información se realizó entre los meses de enero a agosto del 2021. La metodología que se utilizó fue descriptiva y a través de revisión bibliográfica de artículos científicos y de observación para la ayuda en la determinación macroscópica del parásito en hígados en reses que llegaron a ser faenadas en los años ya mencionados del presente estudio. Se tomó la población total de bovinos faenados; que fueron 110 867 en los seis años de estudio, este número disminuyó por restricciones de la pandemia COVID-19 entre los años 2020 y 2021. Se analizó la prevalencia de fascioliasis para todos los años estudio, con un promedio de 7.27%, de esta manera se demuestra la presencia Fascioliasis en el Camal Frigorífico Municipal de Ambato-Ecuador; se recomienda un plan sobre el manejo, prevención, control, tratamiento y erradicación de dicho parásito y dar a conocer a la población sobre los factores de riesgo al consumir alimentos contaminados como higados, berros, vegetales y agua contaminada con larvas. Palabras Clave: Fasciola Hepatica, fascioliasis, seguridad,alimentos,hígados,decomisado

    Rotating Hele-Shaw cells with ferrofluids

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    We investigate the flow of two immiscible, viscous fluids in a rotating Hele-Shaw cell, when one of the fluids is a ferrofluid and an external magnetic field is applied. The interplay between centrifugal and magnetic forces in determining the instability of the fluid-fluid interface is analyzed. The linear stability analysis of the problem shows that a non-uniform, azimuthal magnetic field, applied tangential to the cell, tends to stabilize the interface. We verify that maximum growth rate selection of initial patterns is influenced by the applied field, which tends to decrease the number of interface ripples. We contrast these results with the situation in which a uniform magnetic field is applied normally to the plane defined by the rotating Hele-Shaw cell.Comment: 12 pages, 3 ps figures, RevTe

    Stress Induces Contextual Blindness in Lotteries and Coordination Games

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    In this paper, we study how stress affects risk taking in three tasks: individual lotteries, Stag Hunt (coordination) games, and Hawk-Dove (anti-coordination) games. Both control and stressed subjects take more risks in all three tasks when the value of the safe option is decreased and in lotteries when the expected gain is increased. Also, subjects take longer to take decisions when stakes are high, when the safe option is less attractive and in the conceptually more difficult Hawk-Dove game. Stress (weakly) increases reaction times in those cases. Finally, our main result is that the behavior of stressed subjects in lotteries, Stag Hunt and Hawk-Dove are all highly predictive of each other (p-value < 0.001 for all three pairwise correlations). Such strong relationship is not present in our control group. Our results illustrate a “contextual blindness” caused by stress. The mathematical and behavioral tensions of Stag Hunt and Hawk-Dove games are axiomatically different, and we should expect different behavior across these games, and also with respect to the individual task. A possible explanation for the highly significant connection across tasks in the stress condition is that stressed subjects habitually rely on one mechanism to make a decision in all contexts whereas unstressed subjects utilize a more cognitively flexible approach

    Propagation of chaos for rank-based interacting diffusions and long time behaviour of a scalar quasilinear parabolic equation

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    We study a quasilinear parabolic Cauchy problem with a cumulative distribution function on the real line as an initial condition. We call 'probabilistic solution' a weak solution which remains a cumulative distribution function at all times. We prove the uniqueness of such a solution and we deduce the existence from a propagation of chaos result on a system of scalar diffusion processes, the interactions of which only depend on their ranking. We then investigate the long time behaviour of the solution. Using a probabilistic argument and under weak assumptions, we show that the flow of the Wasserstein distance between two solutions is contractive. Under more stringent conditions ensuring the regularity of the probabilistic solutions, we finally derive an explicit formula for the time derivative of the flow and we deduce the convergence of solutions to equilibrium.Comment: Stochastic partial differential equations: analysis and computations (2013) http://dx.doi.org/10.1007/s40072-013-0014-

    Fen and bog plant communities in the Aran valley, in the central Pyrenees

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    La Vall d’Aran està situada al vessant nord dels Pirineus, on el clima de tipus medioeuropeu i de muntanya amb una marcada influència atlàntica propicia una gran diversitat de molleres. En aquest treball presentem els resultats de l’estudi fitosociològic d’aquestes molleres, especialment d’aquelles que formen part de sistemes complexos (que n’inclouen d’ombrògenes, topògenes, solígenes i limnògenes). Hem seguit la metodologia de Braun-Blanquet per a l’aixecament dels inventaris i hem mesurat també alguns factors ambientals (pH i conductivitat de l’aigua lliure del sòl, profunditat de l’aigua freàtica i gruix de la capa de torba) a part de les variables topogràfiques bàsiques. Presentem 144 inventaris de 22 associacions (una d’elles diversificada en 4 subassociacions), 2 de les quals són noves descripcions, i 8 es documenten per primer cop dels Pirineus. La majoria d’associacions corresponen a la classe Scheuchzerio-Caricetea fuscae (molleres i torberes minerogèniques) i força menys es refereixen a torberes ombrogèniques de la classe Oxycocco-Sphagnetea o a la vegetació lacustre associada de les aliances Magnocaricion, Phragmition i Scorpidio-Utricularion minoris. Valorem la diversitat de torberes en forma de bony de la classe Oxycocco-Sphagnetea i la presència de molleres tremoloses del Caricion lasiocarpae, que constitueixen l’única representació dels Scheuchzerietalia a Catalunya. Reinterpretem les formacions dominades per Scirpus cespitosus, i proposem el nom Vaccinio microphylli-Sphagnetum capillifolii per al que fins ara s’ha anomenat Calluno-Sphagnetum subnitentis Casanovas 1992 (nom. inval.) Com a conclusió general, destaquem la singularitat de la Vall d’Aran per la diversitat i excepcionalitat de les comunitats de molleres que s’hi donen. A més, aquestes formen sistemes molt particulars pel que fa a la hidrologia i al mosaic de comunitats que acullen; en són exemples destacats els de bassa Nera, Planhòla d’Aiguamòg i pla de Tor.Given the topographic situation of the Aran valley, on the north side of the Pyrenees, the climate regimes (from medio-European to high mountain types) have a strong Atlantic influence. This, and the complex relief and bedrock assemblage of the area, enable the formation of great diversity of fens and bogs, covering from mediumsized to small areas. Here we present a phytosociological study of these vegetation units, and especially of those found in the complex systems, where ombrogenous, topogenous, soligenous and limnogenous mires may occur. We obtained field relevés according to the Braun-Blanquet approach, and recorded various associated environmental parameters (pH and conductivity of the soil water, depth of the phreatic water table, peat thickness), as well as topographic descriptors. By means of 144 relevés we discuss 22 associations (one of these split in 4 subassociations), from which 2 are new descriptions and 8 are firstly documented from the Pyrenees. Most of the associations treated are included in the vegetation class Scheuchzerio-Caricetea fuscae (fens), whereas few are referred to the Oxycocco-Sphagnetea ombrogenic bogs or to the neighbouring lacustrine alliances Magnocaricion, Phragmition and Scorpidio-Utricularion minoris. We discuss the diversity of the Oxycocco-Sphagnetea bog hummocks, and the occurrence of the Caricion lasiocarpae floating carpets, which are the sole Scheuchzerietalia representation in Catalonia. Other novelties are the reinterpretation of the Scirpus cespitosus communities, and the new name Vaccinio microphylli-Sphagnetum capillifolii, which properly refers to the Calluno- Sphagnetum subnitentis Casanovas 1992 (nom. inval.). As a general conclusion, we point out the singularity of the Aran valley, referred to the diversity and particularity of the fen and bog communities found. Moreover, these communities are combined into particular systems according to hydrologic aspects, which are especially diverse and outstanding at Bassa Nera, Planhòla d’Aiguamòg and Plan de Tor

    Flora del Massís de la Fembra Morta

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    Aquest treball va guanyar "ex-aequo" el VI Premi Jaume Caresmar i Alemany, atorgat l'any 1998 i convocat conjuntament per l'Ajuntament d'Igualada i el Centre d'Estudis Comarcals d'Igualad
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