The fluctuations of the giant cluster for percolation on random split trees

A split tree of cardinality $n$ is constructed by distributing $n$ "balls" in a subset of vertices of an infinite tree which encompasses many types of random trees such as $m$-ary search trees, quad trees, median-of-$(2k+1)$ trees, fringe-balanced trees, digital search trees and random simplex trees. In this work, we study Bernoulli bond percolation on arbitrary split trees of large but finite cardinality $n$. We show for appropriate percolation regimes that depend on the cardinality $n$ of the split tree that there exists a unique giant cluster, the fluctuations of the size of the giant cluster as $n \rightarrow \infty$ are described by an infinitely divisible distribution that belongs to the class of stable Cauchy laws. This work generalizes the results for the random $m$-ary recursive trees in Berzunza (2015). Our approach is based on a remarkable decomposition of the size of the giant percolation cluster as a sum of essentially independent random variables which may be useful for studying percolation on other trees with logarithmic height; for instance in this work we study also the case of regular trees.Comment: 43 page

Preliminary Observations on Zelus Obscuridorsis (Stål) (Hemiptera: Reduviidae) as Predator of the Corn Leafhopper (Hemiptera: Cicadellidae) in Argentina

The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), is an important corn pest in most of tropical and subtropical America. This leafhopper has a rich natural enemy complex of which parasitoids and pathogens are the most studied; knowledge on its predators is limited. We noted the presence of the native assassin bug Zelus obscuridorsis (Hemiptera: Reduviidae) predating diverse motile insects, including the corn leafhopper, on corn plants cultivated in household vegetable gardens in San Miguel de Tucumán (Argentina); in order to verify its predatory actions, we exposed lab-bred individuals of D. maidis to adults of Z. obscuridorsis. The predators were starved for 24 h before trials in which the corn leafhopper in different developmental stages were exposed. Zelus obscuridorsis is highly skilled in catching specimens in motion, but it was not able to prey on eggs. The predator was capable to catch and prey on nymphs and adults.Fil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Melo, María Cecilia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Speranza, Stefano. Universita Degli Studi Della Tuscia; Itali

Spectral properties of single gold nanoparticles in close proximity to biological fluorophores excited by 2-photon excitation

Metallic nanoparticles (NPs) are able to modify the excitation and emission rates (plasmonic enhancement) of fluorescent molecules in their close proximity. In this work, we measured the emission spectra of 20 nm Gold Nanoparticles (AuNPs) fixed on a glass surface submerged in a solution of different fluorophores using a spectral camera and 2-photon excitation. While on the glass surface, we observed the presence in the emission at least 3 components: i) second harmonic signal (SHG), ii) a broad emission from AuNPS and iii) fluorescence arising from fluorophores nearby. When on the glass surface, we found that the 3 spectral components have different relative intensities when the incident direction of linear polarization was changed indicating different physical origins for these components. Then we measured by fluctuation correlation spectroscopy (FCS) the scattering and fluorescence signal of the particles alone and in a solution of 100 nM EGFP using the spectral camera or measuring the scattering and fluorescence from the particles. We observed occasional fluorescence bursts when in the suspension we added fluorescent proteins. The spectrum of these burst was devoid of the SHG and of the broad emission in contrast to the signal collected from the gold nanoparticles on the glass surface. Instead we found that the spectrum during the burst corresponded closely to the spectrum of the fluorescent protein. An additional control was obtained by measuring the cross-correlation between the reflection from the particles and the fluorescence arising from EGFP both excited at 488 nm. We found a very weak cross-correlation between the AuNPs and the fluorescence confirming that the burst originate from a few particles with a fluorescence signal.Fil: Anzalone, Andrea. University of California at Irvine; Estados UnidosFil: Gabriel, Manuela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Electrónica Cuántica; Argentina. University of California at Irvine; Estados UnidosFil: Estrada, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Electrónica Cuántica; Argentina. University of California at Irvine; Estados UnidosFil: Gratton, Enrico. University of California at Irvine; Estados Unidos. University of New England; Australi

First Record of Zelus obscuridorsis (Hemiptera: Reduviidae) as a Predator of the South American Tomato Leafminer, Tuta absoluta (Lepidoptera: Gelechiidae)

The South American tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a Neotropical key pest of tomato in South America, and in recent years, it has become established in Europe and Africa. Recently we found the native true bug, Zelus obscuridorsis (Stål, 1860) (Hemiptera: Reduviidae), predating diverse mobile insects in household vegetable gardens located in northwestern Argentina. We found that Z. obscuridorsis preys on mobile stages of T. absoluta, i.e., free larvae and adults but not on larvae in their mines, pupae or eggs. This is the first record of a Zelus species as predator of T. absoluta. We discuss the importance of this predator consuming only mobile items, in terms of using little exploited host niches, and its possible relationships with other antagonistic species of T. absoluta.Fil: Speranza, Stefano. Universita Degli Studi Della Tuscia; ItaliaFil: Melo, María Cecilia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Luna, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Virla, Eduardo Gabriel. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

3D microscopy by orbital radially modulated scan

En este trabajo presentamos la implementación de un novedoso método de microscopía 3D basado en el barrido orbital de un haz de excitación alrededor de la estructura de interés. Esta tecnología es capaz de producir imágenes tridimensionales de estructuras en movimiento con resolución nanométrica y en pocas decenas de milisegundos. Dado que la intensidad de luz emitida por un objeto fluorescente depende fuertemente de la distancia entre el haz de excitación y la superficie del mismo, modulando la distancia haz-objeto, y conociendo el perfil del haz de excitación, es posible recuperar la forma del objeto de interés a partir la señal de fluorescencia colectada. El método de nSPIRO (nanoScale Precise Imaging by Rapid beam Oscillation) utiliza la oscilación rápida (en los milisegundos) de una haz de luz enfocado alrededor del objeto para obtener una respuesta oscilatoria cuya amplitud depende únicamente de la distancia a la superficie del objeto. En este trabajo mostramos simulaciones numéricas que permiten evaluar el alcance y las limitaciones del método, mostramos su implementación en un microscopio por absorción de dos fotones, y finalmente lo aplicamos al estudio de raíces de Arabidopsis Thaliana en condiciones fisiológicas.In this work, we present an alternative imaging method based on the orbital scanning of a laser excitation beam around the object of interest. This technology is capable of producing tridimensional images of fluorescent structures with nanometrical resolution in a few milliseconds. The method relies on the fact that when the excitation beam is near a fluorescent object, the emitted light from the object depends on the distance between its surface and the excitation beam. By modulating the distance between the beam and the object and taking into account the nonlinearity of the excitation intensity profile, it is possible to obtain an oscillating response whose amplitude depends only on the distance to the surface of the object. Given the fact that the excitation beam is always near the structure of interest, it is possible to measure moving specimens. Here, we present tridimensional reconstructions of Arabidopsis Thaliana roots which are ~ 50 μm in length and ~ 5 μm in diameter.Fil: Zaza, María Cecilia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gabriel, Manuela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Estrada, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Marmosa (Micoureus) constantiae Thomas (Marsupialia, Didelphidae) como hospedador de Cuterebra Clark (Insecta, Oestridae, Cuterebrinae)

En este trabajo damos a conocer los primeros registros del díptero Cuterebra (Oestridae, Cuterebrinae) parasitando individuos de Marmosa (Micoureus) constantiae capturados camino a Cortaderas (provincia de Salta, Argentina). Las larvas encontradas presentaron un tegumento densamente cubierto de espinas escuamiformes robustas y los espiráculos posteriores con tres pares de serpentinas a modo de laberinto, características que permitieron asociarlas al género Cuterebra. Aunque este género se encuentra ampliamente distribuido en todo el hemisferio occidental, este registro es el primero para marsupiales de la República Argentina, extendiendo ampliamente su distribución hacia el sur y, sobre todo, hacia el oeste.We report the first case of the dipteran Cuterebra (Oestridae, Cuterebrinae) parasitizing individuals of Marmosa (Micoureus) constantiae, which were captured near Cortaderas (Salta Province, Argentina). All the larvae presented a densely-covered integument by robust squamiform spines, and three pairs of posterior spiracular slits in a tortuous form, which allowed us to associate them to the genus Cuterebra. Although the genus is broadly distributed in the Western Hemisphere, this is the f rst record for marsupials in Argentina, extending the parasite’s distribution to the South and West.Fil: Martin, Gabriel Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónica. Universidad Nacional de la Patagonia San Juan Bosco; ArgentinaFil: Brand, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónica. Universidad Nacional de la Patagonia San Juan Bosco; Argentin

Invariance principle for fragmentation processes derived from conditioned stable Galton-Watson trees

Aldous, Evans and Pitman (1998) studied the behavior of the fragmentation process derived from deleting the edges of a uniform random tree on $n$ labelled vertices. In particular, they showed that, after proper rescaling, the above fragmentation process converges as $n \rightarrow \infty$ to the fragmentation process of the Brownian CRT obtained by cutting-down the Brownian CRT along its skeleton in a Poisson manner. In this work, we continue the above investigation and study the fragmentation process obtained by deleting randomly chosen edges from a critical Galton-Watson tree $\mathbf{t}_{n}$ conditioned on having $n$ vertices, whose offspring distribution belongs to the domain of attraction of a stable law of index $\alpha \in (1,2]$. Our main results establish that, after rescaling, the fragmentation process of $\mathbf{t}_{n}$ converges as $n \rightarrow \infty$ to the fragmentation process obtained by cutting-down proportional to the length on the skeleton of an $\alpha$-stable L\'evy tree of index $\alpha \in (1,2]$. We further show that the latter can be constructed by considering the partitions of the unit interval induced by the normalized $\alpha$-stable L\'evy excursion with a deterministic drift studied by Miermont (2001). This extends the result of Bertoin (2000) on the fragmentation process of the Brownian CRT.Comment: 30 pages, 5 figure

La educación como derecho social básico ¿qué nos queda? : un análisis comparado de la política educativa argentina en los '90

Este trabajo se propone comparar el contenido dado por el Estado de Bienestar y el Estado neoliberal a un derecho social básico como es la educación, y en términos más generales a la categoría de ciudadanía. Esta comparación, creemos, será especialmente fértil ya que si bien nos acotaremos al estudio de una política especifica, ésta da cuenta de dos modelos antagónicos, no sólo de Estado, sino también de intervención social, de construcción de la ciudadanía y de distribución de ingresos. Tratamos, entonces, a las políticas educativas de estos modelos con el fin de contextualizarlas y realizar un balance de cada uno de estos momentos en lo que respecta a educación, ciudadanía y pérdida de capacidad de ejercicio real de algunos de nuestros derechos y/o desentendimiento por parte del Estado para garantizarlos.This paper we intend to compare the contents given to a social right such as education, by the Welfare State and the Neo-liberal State. In a more general scope, we intend to analyze the contents of citizenship in both cases. This comparation, we believe, will be specially fruitful, because we focus in a spcific policy, but it shows two antagonic models of the State itself, social intervention, citizenship-building and distribution of income. We work, than, in each of these models and their respective education policies, in order to explain the contexts and make a balance of citizenship and the lack of real excercise of our rights, taking into account the displacement of the State in its effective guarantee.Fil: Álvarez, Hugo Gabriel. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Zsögön, María Cecilia. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y Sociale