Igusa's Local Zeta Functions and Exponential Sums for Arithmetically Non Degenerate Polynomials

We study the twisted local zeta function associated to a polynomial in two variables with coefficients in a non-Archimedean local field of arbitrary characteristic. Under the hypothesis that the polynomial is arithmetically non degenerate, we obtain an explicit list of candidates for the poles in terms of geometric data obtained from a family of arithmetic Newton polygons attached to the polynomial. The notion of arithmetical non degeneracy due to Saia and Z\'u\~niga-Galindo is weaker than the usual notion of non degeneracy due to Kouchnirenko. As an application we obtain asymptotic expansions for certain exponential sums attached to these polynomials.Comment: 20 pages. In this version there is a more precise statement of Lemma 2.4 and a correction to the Example in Section 4. Minor corrections adde

Soil Microbial Community Dynamics In Florida Scrub Ecosystem

Pyrogenic ecosystems are maintained by fires which vary in frequency, seasonality, and intensity. Florida oak-saw palmetto scrub ecosystem is characterized by fires occurring at intervals of 10-20 years. Diverse factors as private land acquisition and development has created a patchy distribution of scrub ecosystems and also interrupted the natural fire cycle. The effects of fire over plant regeneration and fauna habitat utilization of the scrub have been well characterized in previous research. In the present paper the objective is to characterize the short- and long-term fire effects on the soil microbial community. Fire effects were studied in a chronosequence, comprising a recently burned scrub during a winter-prescribed fire to scrub where fire did not occur for 40 years. The number of culturable cells was reduced by two orders of magnitude by indirect fire effects and environmental factors, principally hydric stress. However, the duration of fire effects was very short since the microbial community returned to pre-fire numbers and activity by day 47 after fire. Microbial community activity was distinctively related to inoculum density in the soil and litter samples. Soil and litter microbial communities showed differences in metabolic activity. There was no difference in substrate utilization pattern, but there was significant seasonal variation related to the decrease in water content during the month of May. Substrate utilization by litter microbial communities was higher during the month of January compared to soil microbial communities and this relationship was inversed during the month of May probably associated to the more stringent conditions, low water availability, on the litter layer. Seasonal effects outweighed fire effects in this study as this environmental constraint determined the microbial community structure and activity

A New Host Record for the Egg Parasitoid Anagrus nigriventris (Hymenoptera: Mymaridae) of the Corn Leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae)

A survey of the eggs parasitoids of the corn leafhopper, Dalbulus maidis (DeLong & Wolcott) was carried out in Tucumán Province, Argentina. Samples were collected during the summer of 2004-2005 with sentinel eggs. Anagrus nigriventris Girault was responsible for 7.2% of the total egg parasitism. That is the first record of this parasitoid reared from the eggs of D. maidis; A. nigriventris is one of three species of Anagrus known to affect populations of this leafhopper pest in Argentina.Fil: Luft Albarracin, Erica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Triapitsyn, Serguei V.. University of California; Estados Unido

Sliding Mode Control for Trajectory Tracking of a Non-holonomic Mobile Robot using Adaptive Neural Networks

In this work a sliding mode control method for a non-holonomic mobile robot using an adaptive neural network is proposed. Due to this property and restricted mobility, the trajectory tracking of this system has been one of the research topics for the last ten years. The proposed control structure combines a feedback linearization model, based on a nominal kinematic model, and a practical design that combines an indirect neural adaptation technique with sliding mode control to compensate for the dynamics of the robot. A neural sliding mode controller is used to approximate the equivalent control in the neighbourhood of the sliding manifold, using an online adaptation scheme. A sliding control is appended to ensure that the neural sliding mode control can achieve a stable closed-loop system for the trajectory-tracking control of a mobile robot with unknown non-linear dynamics. Also, the proposed control technique can reduce the steady-state error using the online adaptive neural network with sliding mode control; the design is based on Lyapunov’s theory. Experimental results show that the proposed method is effective in controlling mobile robots with large dynamic uncertaintiesFil: Rossomando, Francisco Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Automática. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Automática; ArgentinaFil: Soria, Carlos Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Automática. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Automática; ArgentinaFil: Carelli Albarracin, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Automática. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Automática; Argentin

670 nm light mitigates oxygen-induced degeneration in C57BL/6J mouse retina

BACKGROUND Irradiation with light wavelengths from the far red (FR) to the near infrared (NIR) spectrum (600 nm -1000 nm) has been shown to have beneficial effects in several disease models. In this study, we aim to examine whether 670 nm red light pretreatment can provide protection against hyperoxia-induced damage in the C57BL/6J mouse retina. Adult mice (90-110 days) were pretreated with 9 J/cm2 of 670 nm light once daily for 5 consecutive days prior to being placed in hyperoxic environment (75% oxygen). Control groups were exposed to hyperoxia, but received no 670 nm light pretreatment. Retinas were collected after 0, 3, 7, 10 or 14 days of hyperoxia exposure (n = 12/group) and prepared either for histological analysis, or RNA extraction and quantitative polymerase chain reaction (qPCR). Photoreceptor damage and loss were quantified by counting photoreceptors undergoing cell death and measuring photoreceptor layer thickness. Localization of acrolein, and cytochrome c oxidase subunit Va (Cox Va) were identified through immunohistochemistry. Expression of heme oxygenase-1 (Hmox-1), complement component 3 (C3) and fibroblast growth factor 2 (Fgf-2) genes were quantified using qPCR. RESULTS The hyperoxia-induced photoreceptor loss was accompanied by reduction of metabolic marker, Cox Va, and increased expression of oxidative stress indicator, acrolein and Hmox-1. Pretreatment with 670 nm red light reduced expression of markers of oxidative stress and C3, and slowed, but did not prevent, photoreceptor loss over the time course of hyperoxia exposure. CONCLUSION The damaging effects of hyperoxia on photoreceptors were ameliorated following pretreatment with 670 nm light in hyperoxic mouse retinas. These results suggest that pretreatment with 670 nm light may provide stability to photoreceptors in conditions of oxidative stress.This work was supported by the Australian Research Council Centre of Excellence in Vision Science

Egg Paeasitoids of Dalbulus maidis (Hemiptera: Cicadellidae) in Jalisco State, Mexico

A survey of eggs parasitoids of the corn leafhopper, Dalbulus maidis (DeLong & Wolcott) was conducted in Jalisco State, Mexico. Samples were collected during the summer of 2008 with sentinel eggs. Five taxa, Anagrus breviphragma Soyka and Polynema sp. (Mymaridae), Paracentrobia nr subflava, Aphelinoidea sp., and Pseudoligosita sp. (Trichogrammatidae) were reared. This is the first reference to an egg parasitoid complex of the corn leafhopper in Mexico, and A. breviphragma is recorded for the first time occurring in Mexico.Fil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Luft Albarracin, Erica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Moya Raygoza, Gustavo. Universidad de Guadalajara; Méxic

Un Nuevo Oriente Medio : connotaciones energéticas de su vinculación a la Unión Europea

Uno de los puntos que se destacará en este trabajo es la reorientación de las relaciones políticas y económicas de los diferentes actores implicados en Oriente Medio para darles unas connotaciones más regionales. Esta tendencia también es perceptible en otras regiones del mundo en las que se combinan globalización con regionalismo de tal modo que un proceso fortalece al otro y originan una mayor cooperación.Un dels punts que es destacarà en aquest treball és la reorientació de les relacions polítiques i econòmiques dels diferents actors implicats en Orient Mitjà per donar-los unes connotacions més regionals. Aquesta tendència també és perceptible en altres regions del món en què es combinen globalització amb regionalisme de tal manera que un procés enforteix l'altre i originen una major cooperació

L'autre, c'est moi : la quête identitaire des Latino-américains transplantés en Europe

Since independence, successive generations of migrants from Latin America have raised the question of their integration or reintegration into Europe, a continent that is established as a paradoxical source of both their identity and otherness. The intellectual and political elites transplants of the nineteenth and twentieth centuries, with many exiles, immigrants or students and researchers who populate today's European universities whose internationalization has become a criterion for developing strategic relationships with Europe and Europeans have evolved?Depuis les indépendances, des générations successives de migrants latino-américains se sont posé la question de leur intégration ou réintégration en Europe, un continent paradoxal qui s'institue comme origine à la fois de leur identité et de leur altérité. Des élites intellectuelles et politiques transplantées des XIXe et XXe siècles, aux nombreux exilés, migrants ou étudiants et chercheurs qui peuplent aujourd'hui les universités d'Europe dont l'internationalisation est devenue un critère de développement stratégique, les rapports à l'Europe et aux Européens ont-ils évolué

Egg Parasitoids of the Leafhoppers Dalbulus maidis and Dalbulus elimatus (Hemiptera: Cicadellidae) in Two Maize Habitats

Este trabajo fue realizado en dos habitats diferentes de maíz en Mexico, con el objetivo de determinar los parasitoides de huevos de dos importantes chicharritas plagas del maíz en este país. se empleó la siguiente metodología: plantas de maíz con similar número de huevos de D. maidis y D. elimatus fueron expuestos a los parasitoides. Ambas especies de chicharritas fueron parasitadas por Paracentrobia tapajosae Viggiani (Hymenoptera: Trichogrammatidae), Anagrus breviphragma Soyka (Hymenoptera: Mymaridae), Aphelinoidea semifuscipennis (Hymenoptera: Trichogrammatidae) y Pseudoligositalongifrangiata (Viggiani) (Hymenoptera: Trichogrammatidae). Todas las especies de parasitoidesque atacan a los huevos de D. elimatus son reportadas por primera vez. Además, en ambas especies de chicharritas se encontró un número similar de huevos parasitados y porcentaje de parasitismo, y los parasitoides encontrados llegaron a su estado adulto. La tasa total de parasitismo depende del tipo de hábitat; en el hábitat donde se cultiva maíz todo el año, una alta tasa de parasitismo fue encontrada, mientras que en el hábitat con maíz estacional, la tasa de parasitismo fue baja.Fil: Moya Raygoza, Gustavo. Universidad de Guadalajara; MéxicoFil: Renteria, Isabel. Universidad de Guadalajara; MéxicoFil: Luft Albarracin, Erica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; Argentin

Descripción de los modelos de motivación laboral implementados en instituciones educativas durante el periodo 2005-2013 (Hispanoamérica)

Hoy en día uno de los temas más relevantes en las instituciones educativas, es la motivación laboral ya que permite centrar el esfuerzo, la energía y la conducta de los trabajadores en especial docentes hacia el logro de los objetivos deseados por las organizaciones educativas en las cuales laboran diariamente; en efecto la motivación laboral se relaciona con la conducta humana, primero por los impulsos: que guían las emociones donde los docentes tienden a caracterizar determinadas situaciones negativamente o positivamente dentro de las instituciones afectando de esta manera el logro de los objetivos pactados.Today one of the most important issues in educational institutions, work motivation is because it allows focusing the effort, energy and behavior of workers especially teachers towards achieving the desired objectives of educational organizations in which work daily, in fact work motivation is related to human behavior, first by impulses: to guide the emotions where teachers tend to characterize certain situations negatively or positively within institutions thus affecting the achievement of the agreed objectives.Pregrad