6,161 research outputs found

    Development and Sex Ratio of \u3ci\u3eMelittobia Australica\u3c/i\u3e and \u3ci\u3eM. Digitata\u3c/i\u3e (Hymenoptera: Eulophidae) on \u3ci\u3eMegachile Rotundata\u3c/i\u3e (Hymenoptera: Megachilidae) and \u3ci\u3eTrypoxylon Politum\u3c/i\u3e (Hymenoptera: Sphecidae)

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    Life history, development time, and sex ratio of Melittobia australica Girault and M. digitata Dahms on Megachile rotundata (Fabricius) and Trypoxylon politum Say are presented and compared with previous reports. Total development time and sex ratio differs slightly among the different hosts but falls within the expected range reported for different hosts and Melittobia species. The slightly longer development times and higher proportion of males recorded for both species on M. rotundata hosts probably reflects poorer host nutritional quality, relative to T. politum. We confirm that the one unusually extended development time reported by Schmieder for Melittobia chalybii Ashmead collected in New Jersey, can be accounted for as likely having represented a previously unknown species since described as M. femorata Dahms

    Survivability Analysis on Non-Triconnected Optical Networks under Dual-Link Failures

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    Survivability of optical networks is considered among the most critical problems that telecommunications operators need to solve at a reasonable cost. Survivability can be enhanced by increasing the amount of network links and its spare capacity, nevertheless this deploys more resources on the network that will be used only under failure scenarios. In other words, these spare resources do not generate any direct profit to network operators as they are reserved to route only disrupted traffic. In particular, the case of dual link failures on fiber optic cables (i.e., fiber cuts) has recently received much attention as repairing these cables typically requires much time, which then increases the probability of a second failure on another link of the network. In this context, survivability schemes can be used to recover the network from a dual link failure scenario. In this work, we analyze the case of protection and restoration schemes, which are two well-known recovery strategies. The former is simpler to implement as it considers a fixed set of backup paths for all failure scenarios; however, it cannot take into account the spare capacity released by disrupted connections. Instead, the latter computes the best recovery path considering not only the spare capacity but also the released one due to failures. Achieving 100% survivability (i.e., recovery from all possible dual link failures) requires a triconnected network, where three disjoint paths for each connection are required. Since these networks can become extremely expensive since they can require a huge number of network links (i.e., fibers connections), a more realistic case of non-triconnected networks is assumed. In these networks, full network recovery is not be feasible, but achieving the maximum possible survivability is desired. Spare capacity can then be allocated to existing network links, which represents the actual cost of the survivability. We propose optimization models that take into account these different recovery strategies, and demonstrate that restoration has the potential to provide a much better recovery capability with almost the same amount of spare capacity required in protection schemes.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Survivability Analysis on Non-Triconnected Optical Networks under Dual-Link Failures

    Get PDF
    Survivability of optical networks is considered among the most critical problems that telecommunications operators need to solve at a reasonable cost. Survivability can be enhanced by increasing the amount of network links and its spare capacity, nevertheless this deploys more resources on the network that will be used only under failure scenarios. In other words, these spare resources do not generate any direct profit to network operators as they are reserved to route only disrupted traffic. In particular, the case of dual link failures on fiber optic cables (i.e., fiber cuts) has recently received much attention as repairing these cables typically requires much time, which then increases the probability of a second failure on another link of the network. In this context, survivability schemes can be used to recover the network from a dual link failure scenario. In this work, we analyze the case of protection and restoration schemes, which are two well-known recovery strategies. The former is simpler to implement as it considers a fixed set of backup paths for all failure scenarios; however, it cannot take into account the spare capacity released by disrupted connections. Instead, the latter computes the best recovery path considering not only the spare capacity but also the released one due to failures. Achieving 100% survivability (i.e., recovery from all possible dual link failures) requires a triconnected network, where three disjoint paths for each connection are required. Since these networks can become extremely expensive since they can require a huge number of network links (i.e., fibers connections), a more realistic case of non-triconnected networks is assumed. In these networks, full network recovery is not be feasible, but achieving the maximum possible survivability is desired. Spare capacity can then be allocated to existing network links, which represents the actual cost of the survivability. We propose optimization models that take into account these different recovery strategies, and demonstrate that restoration has the potential to provide a much better recovery capability with almost the same amount of spare capacity required in protection schemes.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Universal functions and exactly solvable chaotic systems

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    A universal differential equation is a nontrivial differential equation the solutions of which approximate to arbitrary accuracy any continuous function on any interval of the real line. On the other hand, there has been much interest in exactly solvable chaotic maps. An important problem is to generalize these results to continuous systems. Theoretical analysis would allow us to prove theorems about these systems and predict new phenomena. In the present paper we discuss the concept of universal functions and their relevance to the theory of universal differential equations. We present a connection between universal functions and solutions to chaotic systems. We will show the statistical independence between X(t)X(t) and X(t+τ)X(t + \tau) (when τ\tau is not equal to zero) and X(t)X(t) is a solution to some chaotic systems. We will construct universal functions that behave as delta-correlated noise. We will construct universal dynamical systems with truly noisy solutions. We will discuss physically realizable dynamical systems with universal-like properties.Comment: 12 Pages, 9 figures. Proceedings 1st Meeting IST-IM

    HD149277: A rare short-period SB2 system with a subsynchronously rotating magnetic He-rich primary

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    HD149277 is a rare SB2 system with a slowly rotating magnetic He-rich primary with Prot = 25.4 d. The CFHT/ESPaDOnS archive spectra revealed Porb = 11.5192 ± 0.0005 d indicating strong subsynchronous rotation of the primary component. Such a strong subsynchronous rotation was not detected in any other SB2 system with a magnetic chemically peculiar component. Our inspection of the spectra revealed the presence of resolved Zeeman split spectral lines allowing us to determine the variability of the mean magnetic field modulus over the rotation period. The maximum of the magnetic field modulus coincides roughly with the positive extremum of the longitudinal field, whereas the minimum of the modulus with the negative extremum of the longitudinal field. No evidence for a longitudinal magnetic field was seen in the circularly polarized spectra of the secondary component. Using archival data from the ASAS3 survey, we find in the frequency spectrum only one significant peak, corresponding to the period Pphot = 25.390 ± 0.014 d. This value is in good agreements with the previous determination of the rotation period, Prot =25.380±0.007 d, which was based on longitudinal magnetic field measurements.Fil: Gonzalez, Jorge Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Hubrig, S.. Leibniz Institute For Astrophysics Potsdam; AlemaniaFil: Järvinen, S. P.. Leibniz Institute For Astrophysics Potsdam; AlemaniaFil: Schöller, M.. European Southern Observatory; Alemani

    Small strain stiffness within logarithmic contractancy model for structured anisotropic clay.

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    ABSTRACT: Stiffness of soils in the small strain region is high and it decays nonlinearly with increasing shear strains or with mobilization of shear stresses. However, the commonly used critical state based constitutive models use a simple elastic formulation at small strains that falls short in the prediction of the small strain nonlinearity and anisotropy. This paper proposes a simple way for rendering the existing constitutive models with the capability to capture the small strain behaviour of soils. This is illustrated by proposing a new model for structured anisotropic clay extending an existing model that uses the framework of logarithmic contractancy called ESCLAY1S. The proposed model is implemented into a Finite Element program as a user-defined soil model. The model predictions are compared with experimental data for various clays. Furthermore, the effect of nonlinearity is investigated for an excavation in soft clay

    Lineamiento estategico para la formulacion de un plan de desarrollo turistico para la comuna de Curepto, Region del Maule

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    184 p.El propósito de esta investigación es diseñar lineamientos estratégicos para la formulación de un Plan de Desarrollo Turístico, para permitir a la comunidad mostrar todos sus atributos turísticos (Atractivos, Actividades, Planta, Infraestructura, entre otros) a nivel comunal, regional y nacional, a fin de aumentar el flujo de turistas que recibe la comuna cada año, logrando impactos positivos tanto a nivel económico como sociocultural. Para lograr este propósito, la información se recabó tanto de fuentes primarias como secundarias. Se realizó una revisión bibliográfica sobre todos los temas relacionados con un Plan de Desarrollo Turístico, de Curepto, y con el tema turismo en general. Esta revisión bibliográfica ayudó a determinar el público objetivo, identificando la demanda potencial en términos cualitativos, obteniendo conclusiones importantes sobre todo de los distintos gustos y preferencias que tienen las personas de los distintos estratos socioeconómicos al momento de vacacionar. En tanto las fuentes primarias fueron compuestas por las siguientes actividades: grupos foco, entrevistas en profundidad, entrevistas con informantes claves, observación directa y encuestas. La información que se obtuvo permitió conocer lo que piensan los cureptanos sobre el pueblo y cuales son sus proyecciones en el tema del turismo. Se entrevistaron actores como las autoridades locales, microempresarios de la comuna y a residentes, además de una entrevista con la encargada del Departamento de Planificación de la oficina de Sernatur de la Región del Maule, y con el Director Regional de Sernatur. Así se estableció la realidad que vive Curepto en el tema Turismo, sus principales falencias, limitaciones, fortalezas y oportunidades. Las principales conclusiones sobre el estudio, apuntan a que Curepto posee un potencial turístico que está en desarrollo en el turismo. Pero existe un gran déficit en la planta turística, por lo que se deben hacer muchos esfuerzos para introducir y mejorar el servicio y ofrecer lugares atractivos para el visitante, más cómodos, acogedores y con sólida infraestructura vial. Dado lo anterior se formula un lineamiento estratégico de Pladetur que servirá de gran apoyo para el municipio y la comunidad en general. Finalmente, y como resultado de todos los estudios realizados, se concluye que el turismo forma parte importante y fundamental de una futura gran actividad económica para la comuna de Curepto
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