The Multidimensional Study of Viral Campaigns as Branching Processes

Viral campaigns on the Internet may follow variety of models, depending on the content, incentives, personal attitudes of sender and recipient to the content and other factors. Due to the fact that the knowledge of the campaign specifics is essential for the campaign managers, researchers are constantly evaluating models and real-world data. The goal of this article is to present the new knowledge obtained from studying two viral campaigns that took place in a virtual world which followed the branching process. The results show that it is possible to reduce the time needed to estimate the model parameters of the campaign and, moreover, some important aspects of time-generations relationship are presented.Comment: In proceedings of the 4th International Conference on Social Informatics, SocInfo 201

The evolution of Balmer jump selected galaxies in the ALHAMBRA survey

We present a new color-selection technique, based on the Bruzual & Charlot models convolved with the bands of the ALHAMBRA survey, and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 < z < 1.5. These galaxies are dubbed Balmer jump Galaxies BJGs. We apply the iSEDfit Bayesian approach to fit each detailed SED and determine star-formation rate (SFR), stellar mass, age and absolute magnitudes. The mass of the haloes where these samples reside are found via a clustering analysis. Five volume-limited BJG sub-samples with different mean redshifts are found to reside in haloes of median masses $\sim 10^{12.5 \pm 0.2} M_\odot$ slightly increasing toward z=0.5. This increment is similar to numerical simulations results which suggests that we are tracing the evolution of an evolving population of haloes as they grow to reach a mass of $\sim 10^{12.7 \pm 0.1} M_\odot$ at z=0.5. The likely progenitors of our samples at z$\sim$3 are Lyman Break Galaxies, which at z$\sim$2 would evolve into star-forming BzK galaxies, and their descendants in the local Universe are elliptical galaxies.Hence, this allows us to follow the putative evolution of the SFR, stellar mass and age of these galaxies. From z$\sim$1.0 to z$\sim$0.5, the stellar mass of the volume limited BJG samples nearly does not change with redshift, suggesting that major mergers play a minor role on the evolution of these galaxies. The SFR evolution accounts for the small variations of stellar mass, suggesting that star formation and possible minor mergers are the main channels of mass assembly.Comment: 14 pages, 10 figures. Submitted to A&A. It includes first referee's comments. Abstract abridged due to arXiv requirement

Random Walks on Stochastic Temporal Networks

In the study of dynamical processes on networks, there has been intense focus on network structure -- i.e., the arrangement of edges and their associated weights -- but the effects of the temporal patterns of edges remains poorly understood. In this chapter, we develop a mathematical framework for random walks on temporal networks using an approach that provides a compromise between abstract but unrealistic models and data-driven but non-mathematical approaches. To do this, we introduce a stochastic model for temporal networks in which we summarize the temporal and structural organization of a system using a matrix of waiting-time distributions. We show that random walks on stochastic temporal networks can be described exactly by an integro-differential master equation and derive an analytical expression for its asymptotic steady state. We also discuss how our work might be useful to help build centrality measures for temporal networks.Comment: Chapter in Temporal Networks (Petter Holme and Jari Saramaki editors). Springer. Berlin, Heidelberg 2013. The book chapter contains minor corrections and modifications. This chapter is based on arXiv:1112.3324, which contains additional calculations and numerical simulation

Cerámica y vibración de la luz. Nuevas técnicas de nacarado e irisado y caracterización colorimétrica

Recent years have witnessed the development of innovative applications for ceramic materials as building envelopes. However, little research has been conducted on the relationship between these materials and reflected light, visual perception and integration in the landscape. The aim of the present research was to study the production and application of porcelain stoneware panels in an auditorium. The idea behind using a ceramic coating with an iridescent, pearlescent finish and a metallic sheen was to create a vibrant, constantly changing surface that reflected the natural light and the environment. We designed a metal deposition and glazing process based on three successive firings, and analysed the glaze properties and microcracking factors that reinforced the iridescent lustre. We also performed a colorimetric analysis to assess the goniochromatic or iridescent colours, measuring the spectral radiance of the light.Los materiales cerámicos han abierto nuevos espacios de innovación en su aplicación en las envolventes de los edificios en los últimos años. Sin embargo, ha sido escasa la investigación en su relación con la vibración de la luz, la percepción visual y su integración en el paisaje. En esta investigación se estudia la producción y aplicación de piezas de gres porcelánico en un auditorio. El uso de un recubrimiento cerámico con un acabado irisado-nacarado con reflejo metálico responde a la intención de generar una piel vibrante en constante cambio frente a la luz natural y el entorno. Se ha diseñado un proceso de vitrificado y deposición de metales, a través de tres cocciones sucesivas. Se analizan las propiedades del esmaltado y los factores de microfisuración que refuerzan el irisado. Se ha hecho un análisis colorimétrico evaluando los colores goniocromáticos o iridiscentes, midiendo el factor de radiancia espectral de la luz

Cerámica y climatización saludable: paneles cerámicos radiantes en edificios. Condiciones de confort y demanda energética frente a sistemas convectivos

Porcelain stoneware is a widely used building material. In recent years, its range of uses has expanded to encompass a new spectrum of innovative and inventive applications in architecture. In this research, we analysed the patented Thermal Ceramic Panel. This consists of a thin porcelain stoneware panel that incorporates a capillary system of polypropylene tubes measuring 3.5 mm in diameter embedded in a conductive ceramic interface. The system works with hot or cold water, producing healthy heating and cooling by means of radiant surfaces. Following an initial prototype test in which panels were placed on the walls of an office, we conducted simulations at the University of Alicante Museum using wall, ceiling and baffle panels, having previously monitored the state of the building. Thermal behaviour parameters were analysed and compared with those of other standard finishing materials, obtaining results for thermal comfort and energy savings in comparison with all-air systems.El gres porcelánico es un material ampliamente utilizado en edificación. En los últimos años su uso ha experimentado un nuevo espectro de líneas de innovación e invención en sus aplicaciones en la arquitectura. En esta investigación de analiza la patente Panel de Acondicionamiento Térmico Cerámico, consistente en piezas de gres porcelánico de bajo espesor, que contienen tramas capilares a base de tubos de polipropileno de 3,5 mm de diámetro, e interfaz de pasta conductora. Estos sistemas trabajan con agua fría o caliente produciendo una climatización saludable por superficies radiantes. Tras una primera experiencia de prototipado y colocación de paneles en pared en un despacho de oficina, se han realizado simulaciones en el Museo de la Universidad de Alicante, colocando los paneles en pared, techo o tipo bafle, previa monitorización del estado actual del edificio. Se han analizado los parámetros de comportamiento térmico y se han comparado con otros materiales de acabado habituales. Se han obtenido resultados de confort térmico y ahorros energéticos de forma comparativa frente a sistemas todo-aire

Resolución quirúrgica de la colecistitis aguda. ¿Influye el tiempo de evolución?

ResumenIntroducciónLa colecistectomía laparoscópica precoz es nuestra conducta para el tratamiento de la colecistitis aguda; sin embargo, la consulta tardía y el tratamiento postergado por dificultades de acceso hacen que el tiempo de resolución muchas veces sobrepase los 7 días de iniciados los síntomas.Nuestro objetivo es comparar los resultados quirúrgicos entre los pacientes operados antes y después de este periodo.Material y métodosSerie de casos consecutivos de pacientes con diagnóstico de colecistitis aguda operados entre junio de 2013 y diciembre de 2014 en el Servicio de Cirugía del Hospital de Coquimbo. De 358 casos, se excluyen aquellos asociados a colangitis, pancreatitis aguda, ASA ≥4 y cuadro mayor de 30 días. Consecuentemente se incluyen 233 pacientes que se dividen en «grupo precoz» (GP), operados antes del séptimo día de iniciados los síntomas, y «grupo tardío» (GT), operados después de este periodo. Se analizan la presentación de la serie y la asociación entre variables cualitativas y cuantitativas mediante la prueba de χ2 y t de Student, respectivamente.ResultadosEl GP presenta una estadía hospitalaria de 3,9 (±2,0) días y el GT de 7,2 (±5,2), (p=0,0001); el periodo postoperatorio es de 1,9 (±1,6) y de 2,9 (±4,4) días, respectivamente (p=0,055). La tasa de conversión en el GP es del 2,1% y en el GT del 9,7% (p=0,027); la tasa global de complicaciones postoperatorias es del 3,2 y 10,7%, respectivamente (p=0,033).DiscusiónNuestros resultados respaldan la colecistectomía precoz en pacientes con colecistitis aguda. Se pone de manifiesto un problema de gestión, en que la postergación de la resolución quirúrgica empeora los resultados y conlleva mayor riesgo de complicaciones.AbstractIntroductionThe treatment for acute Cholecystitis should be an early Laparoscopic Cholecystectomy. However, this resolution often exceed 7 days after the clinical symptoms onset. Mainly, for delayed consultation of the patients, access difficulties and delayed surgical resolution in our hospital.The aim is compare the surgical outcomes of patients that have had a Cholecystectomy before 7 days after the clinical symptoms onset with those operated after this period.Material and methodsBetween June 2013 and December 2014, 358 patients were Cholecystectomy for acute Cholecystitis at the Hospital of Coquimbo. Those associated to Cholangitis, Acute Pancreatitis, ASA ≥4 and Gallbladder Cancer, were excluded; 233 patients were included. They were allocated into two groups according to the treatment timeframe: ‘Early Group’ (EG) for those operated before the seventh day of symptoms onset and ‘Late Group’ (LG) for those operated after this period. A retrospective study was used to collect data demographics, clinical and surgical outcomes. All these factors were compared between the two groups.ResultsThe EG had a hospital stay of 3.9 (±2.0) days and the LG 7.2 (±5.2) (P=.0001); the postoperative stay was 1.9 (±1.6) and 2.9 (±4.4) (P=.055) days, respectively. The conversion rate in the EG was 2.1% and 9.7% in the LT (P=.027); the overall rate of postoperative complications was 3.2% and 10.7% (P=.033), respectively.ConclusionsThe findings support an early Cholecystectomy in patients with acute cholecystitis. There is a management problem in terms of delayed surgical resolution which worsens surgical outcomes and increase morbidity

Characterization of wood-laden flows in rivers

Inorganic sediment is not the only solid‐fraction component of river flows; flows may also carry significant amounts of large organic material (i.e., large wood), but the characteristics of these wood‐laden flows (WLF) are not well understood yet. With the aim to shed light on these relatively unexamined phenomena, we collected home videos showing natural flows with wood as the main solid component. Analyses of these videos as well as the watersheds and streams where the videos were recorded allowed us to define for the first time WLF, describe the main characteristics of these flows and broaden the definition of wood transport regimes (adding a new regime called here hypercongested wood transport). According to our results, WLF may occur repeatedly, in a large range of catchment sizes, generally in steep, highly confined single thread channels in mountain areas. WLF are typically highly unsteady and the log motion is non‐uniform, as described for other inorganic sediment‐laden flows (e.g., debris flows). The conceptual integration of wood into our understanding of flow phenomena is illustrated by a novel classification defining the transition from clear water to hypercongested, wood and sediment‐laden flows, according to the composition of the mixture (sediment, wood, and water). We define the relevant metrics for the quantification and modelling of WLF, including an exhaustive discussion of different modelling approaches (i.e., Voellmy, Bingham and Manning) and provide a first attempt to simulate WLF. We draw attention to WLF phenomena to encourage further field, theoretical, and experimental investigations that may contribute to a better understanding of flows river basins, leading to more accurate predictions, and better hazard mitigation and management strategies

Timing interactions in social simulations: The voter model

The recent availability of huge high resolution datasets on human activities has revealed the heavy-tailed nature of the interevent time distributions. In social simulations of interacting agents the standard approach has been to use Poisson processes to update the state of the agents, which gives rise to very homogeneous activity patterns with a well defined characteristic interevent time. As a paradigmatic opinion model we investigate the voter model and review the standard update rules and propose two new update rules which are able to account for heterogeneous activity patterns. For the new update rules each node gets updated with a probability that depends on the time since the last event of the node, where an event can be an update attempt (exogenous update) or a change of state (endogenous update). We find that both update rules can give rise to power law interevent time distributions, although the endogenous one more robustly. Apart from that for the exogenous update rule and the standard update rules the voter model does not reach consensus in the infinite size limit, while for the endogenous update there exist a coarsening process that drives the system toward consensus configurations.Comment: Book Chapter, 23 pages, 9 figures, 5 table

Estructura genética de poblaciones de Phytophthora capsici en el noreste de la provincia de Buenos Aires, Argentina

Phytophthora capsici causa enfermedades destructivas en todo el mundo. El patógeno es heterotálico y los dos tipos de apareamiento (TAs) son requeridos para la reproducción sexual. La razón de TAs varía entre regiones geográficas y por lo tanto también la chance para reproducirse sexualmente. Si se toma en cuenta que la durabilidad de las medidas de control depende de la variación genética, es aconsejable considerar la cantidad y la distribución de variación genética dentro y entre poblaciones de especies, es decir, la estructura genética. Esta está determinada por factores que influencian la evolución poblacional como la mutación, la deriva genética, el flujo genético, el sistema de reproducción y de selección. En este sentido, poco se conoce sobre las poblaciones de P. capsici en Argentina. El objetivo fue evaluar la variabilidad genética de aislamientos de P. capsici de tres sitios de producción hortícola del NE de Buenos Aires. Sesenta y un aislamientos de P. capsici colectados de cultivos de Capsicum annuum, Solanum melongena, Solanum lycopersicum y Cucurbita spp. fueron identificados morfológicamente y analizados por tipo de reproducción. Los aislamientos fueron identificados por técnicas moleculares basadas en las secuencias de las regiones ITS1-5.8S e ITS2 del ADNr. Se definieron los haplotipos para cada aislamiento y los parámetros poblacionales fueron estimados por zona geográfica y por especie hospedante junto con el número mínimo de eventos de recombinación. Las desviaciones de la coalescencia básica fueron estimadas a través de Tajima´s D.; la estructura genética fue evaluada subsecuentemente a través de pruebas de AMOVA y de estimadores de Fst. La reconstrucción de redes filogenéticas fue analizada con la intención de evaluar las relaciones genealógicas entre haplotipos. Todos los aislamientos mostraron características morfológicas y genéticas típicas de P. capsici y pertenecieron al TA A1. No se evidenció una estructura genética cuando fueron incluidas como criterio de partición las especies hospedantes. Sin embargo, la partición geográfica permitió evidenciar alguna estructuración entre poblaciones, con la excepción de Exaltación de La Cruz que resultó el sitio más contrastante con respecto a ambos estimadores de índices de fijación. Al mismo tiempo, esta ubicación redituó los estimadores más bajos de diversidad, lo que probablemente refleja su origen reciente como zona hortícola. Dos a tres eventos de recombinación fueron detectados, lo que sugiere que la reproducción sexual podría haber influido sobre el proceso de diversificación en esta área. La estructura genética y los niveles de variación en esta región son opuestos a los resultados obtenidos por otros investigadores en la región centro oeste de Argentina y podría significar una amenaza para esta área de cultivo, al presente.Phytophthora capsici causes destructive diseases worldwide. The pathogen is heterothallic and the two mating types (MTs) are required for sexual reproduction. MTs rates vary amongst geographical regions and so does the chance for sexual reproduction. Taking into account that the durability of control measures depends upon genetic variation, it is advisable to consider its structure within and between populations. The objective of the present paper was to evaluate the genetic variability of P. capsici isolates from three horticultural production areas of the Northeast of Buenos Aires. Sixty one isolates of P. capsici collected from Capsicum annuum, Solanum melongena, Solanum lycopersicum and Cucurbita spp. crops were morphologically identified and analyzed for MTs. The isolates were further identified via molecular techniques based on the sequences of the ITS1 - 5.8S - ITS2 region of the ADNr. Haplotypes were defined for every isolate, and population parameterts were estimated both for geographic and hostspecies partitions, along with the minimum number of recombination events. Departures from the basic coalescent were estimated through Tajima´s D; the genetic structure was subsequently evaluated through AMOVA tests and Fst estimations. Phylogenetic network reconstruction was analysed in an attempt to assess genealogical relationships amongst haplotypes. All isolates showed morphological and genetic characteristics of P. capsici and belonged to the A1 MT. No genetic structure was detected when host-species was taken as a criterion for partition; on the other hand, geographic partition detected some structure among populations, with Exaltación de La Cruz resulting in the most contrasting site with regards to both fixation index estimates. At the same time, this location yielded the lowest estimates of diversity, probably reflecting its recent horticultural origin. Two to three recombination events were detected, suggesting that sexual reproduction could have been part of the diversification process in this area. The genetic structure and levels of variation in the region is opposite to what other researchers have found in Northwestern Argentina and could mean a threat to that breeding area now.Gerencia de Comunicación e Imagen InstitucionalFil: Iribarren, Maria Josefina. Universidad Nacional de Luján; ArgentinaFil: Borassi, C. Universidad Nacional de Luján; ArgentinaFil: Ferri, Andrea Matilde. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; ArgentinaFil: González, B. Universidad Nacional de Luján; ArgentinaFil: Steciow, M. Universidad Nacional de La Plata; ArgentinaFil: Guillin, Eduardo Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; Argentin