No sex-biased dispersal in a primate with an uncommon social system-cooperative polyandry.

An influential hypothesis proposed by Greenwood (1980) suggests that different mating systems result in female and male-biased dispersal, respectively, in birds and mammals. However, other aspects of social structure and behavior can also shape sex-biased dispersal. Although sex-specific patterns of kin cooperation are expected to affect the benefits of philopatry and dispersal patterns, empirical evidence is scarce. Unlike many mammals, Saguinus geoffroyi (Geoffroy's tamarin) has a breeding system in which typically multiple males mate with a single breeding female. Males typically form cooperative reproductive partnerships between relatives, whereas females generally compete for reproductive opportunities. This system of cooperative polyandry is predicted to result in female-biased dispersal, providing an opportunity to test the current hypotheses of sex-biased dispersal. Here we test for evidence of sex-biased dispersal in S. geoffroyi using demographic and genetic data from three populations. We find no sex bias in natal dispersal, contrary to the prediction based on the mating patterns. This pattern was consistent after controlling for the effects of historical population structure. Limited breeding opportunities within social groups likely drive both males and females to disperse, suggesting that dispersal is intimately related to the social context. The integration of genetic and field data revealed that tamarins are another exception to the presumed pattern of male-biased dispersal in mammals. A shift in focus from mating systems to social behavior, which plays a role in most all processes expected to influence sex-bias in dispersal, will be a fruitful target for research both within species and across taxa

Role of recent and old riverine barriers in fine-scale population genetic structure of Geoffroy's tamarin (Saguinus geoffroyi) in the Panama Canal watershed

The role of physical barriers in promoting population divergence and genetic structuring is well known. While it is well established that animals can show genetic structuring at small spatial scales, less well-resolved is how the timing of the appearance of barriers affects population structure. This study uses the Panama Canal watershed as a test of the effects of old and recent riverine barriers in creating population structure in Saguinus geoffroyi, a small cooperatively breeding Neotropical primate. Mitochondrial sequences and microsatellite genotypes from three sampling localities revealed genetic structure across the Chagres River and the Panama Canal, suggesting that both waterways act as barriers to gene flow. F-statistics and exact tests of population differentiation suggest population structure on either side of both riverine barriers. Genetic differentiation across the Canal, however, was less than observed across the Chagres. Accordingly, Bayesian clustering algorithms detected between two and three populations, with localities across the older Chagres River always assigned as distinct populations. While conclusions represent a preliminary assessment of genetic structure of S. geoffroyi, this study adds to the evidence indicating that riverine barriers create genetic structure across a wide variety of taxa in the Panama Canal watershed and highlights the potential of this study area for discerning modern from historical influences on observed patterns of population genetic structure

Next-generation sequencing of dsRNA is greatly improved by treatment with the inexpensive denaturing reagent DMSO.

dsRNA is the genetic material of important viruses and a key component of RNA interference-based immunity in eukaryotes. Previous studies have noted difficulties in determining the sequence of dsRNA molecules that have affected studies of immune function and estimates of viral diversity in nature. DMSO has been used to denature dsRNA prior to the reverse-transcription stage to improve reverse transcriptase PCR and Sanger sequencing. We systematically tested the utility of DMSO to improve the sequencing yield of a dsRNA virus (Φ6) in a short-read next-generation sequencing platform. DMSO treatment improved sequencing read recovery by over two orders of magnitude, even when RNA and cDNA concentrations were below the limit of detection. We also tested the effects of DMSO on a mock eukaryotic viral community and found that dsRNA virus reads increased with DMSO treatment. Furthermore, we provide evidence that DMSO treatment does not adversely affect recovery of reads from a ssRNA viral genome (influenza A/California/07/2009). We suggest that up to 50 % DMSO treatment be used prior to cDNA synthesis when samples of interest are composed of or may contain dsRNA

Supporting Diversity in Science through Social Networking

In this Community Page, we learn how a scientific community leverages social networking tools to connect a group of dispersed scientific researchers in Ciencia Puerto Rico; this effort fosters innovative research and educational collaborations and changes the way scientists interact with the public

MODELO ESTADÍSTICO PARA LA REALIZACIÓN DE ANALOGÍAS ORIENTADAS A PROCESOS DE RECOBRO MEJORADO

Se desarrolló un modelo estadístico que permite analizar campos a nivel mundial en los que se haya implementado métodos de Recobro Mejorado y compararlos con campos colombianos en los que puedan ser aplicados estos métodos. Se implementó una aplicación software denominada EORS, que sirve para realizar analogías usando el modelo desarrollado. Este modelo puede aplicarse a cualquier método de recobro mejorado o a cualquier área de la ingeniería, en la que se involucren varios parámetros y se tenga que sopesar la importancia de cada uno de ellos. Palabras claves: Recobro Mejorado; analogías; modelo estadístico; screening

METODOLOGÍA PARA EL DISEÑO DE BACHES EN UN PROCESO DE INYECCIÓN DE POLÍMEROS PARA RECOBRO MEJORADO, CONSIDERANDO FENÓMENOS DE INTERACCIÓN ROCA/FLUIDOS.

RESUMENLa inyección de polímeros es un proceso de recobro mejorado que fue desarrollado para realizar mejoras  en la inyección de agua convencional. Esta técnica se enfoca en el aprovechamiento de la viscosidad, propia de las soluciones poliméricas para controlar la movilidad de los fluidos en la formación, con el fin de lograr un barrido más uniforme del yacimiento y a su vez lograr un mayor desplazamiento de petróleo. Debido a la necesidad de aumentar las reservas de hidrocarburos mediante el uso de estrategias para optimizar la producción de los campos, la implementación de este proceso se hace atractivo en yacimientos sometidos a inyección de agua con resultados desfavorables; sin embargo, para que sea exitosa su aplicación, el diseño del bache de polímero a ser inyectado juega un papel fundamental, ya que la naturaleza del flujo en medios porosos e interacciones roca-fluido conducen a la disminución de la eficacia del bache con una consecuente reducción en la eficiencia del proceso, razón por la cual los volúmenes a inyectar deben ser apropiadamente ajustados para tolerar pérdidas y/o cambios de concentración y aun así conservar sus propiedades fisicoquímicas para cumplir con el objetivo para el cual fue diseñado. Por lo anterior, la comprensión de estos fenómenos son consideraciones claves para el diseño del bache en estos procesos, procurando que éste se mantenga durante un cierto periodo mínimo de flujo aceptable.El presente artículo se enfoca en el desarrollo de una metodología para el diseño de baches en procesos de inyección de polímeros, basada en el análisis de los fenómenos de interacción roca-fluidos presentes en el medio poroso. Fue orientada inicialmente en la realización de una herramienta computacional útil para el pre-diseño del bache, la cual involucra modelos analíticos que incorporan éstos fenómenos, con el objetivo de sensibilizar variables inherentes al diseño del bache y observar el comportamiento de la concentración de un fluido inyectado en el yacimiento en función del tiempo y de la distancia y su afectación con los fenómenos de interacción presentes en el yacimiento. Seguidamente, ya que los modelos analíticos no contemplan a la vez todos los fenómenos de difusión, dispersión y adsorción en la roca, se desarrolló un modelo de simulación (sector model) en la plataforma STARS de CMG Ltda, la cual permite modelar proyectos de inyección de químicos, donde se consideraron los resultados obtenidos con la herramienta informática desarrollada, con el fin de realizar un análisis de sensibilidad de los parámetros operacionales que influyen en el diseño del bache. A partir del análisis de 1. Grupo de investigación recobro mejorado, Escuela de Ingeniería de Petróleos, Universidad Industrial de Santander, UIS, Carrera 27 calle 9, Bucaramanga, Colombia.2. Grupo de investigación recobro mejorado, Escuela de Ingeniería de Petróleos, Universidad Industrial de Santander, UIS, Carrera 27 calle 9, Bucaramanga, Colombia.3. Instituto Colombiano del Petróleo, ICP, Ecopetrol, Vía Piedecuesta # Km7, Piedecuesta, Colombia.REVISTA FUENTES, El Reventón Energético Vol. 12 Nº 2estas variables, y considerándose como unidad de análisis el factor de recobro, las tasas de producción de los fluidos producidos, velocidad de avance, eficiencia de barrido y cortes de agua, se pueden determinar las mejores condiciones operacionales del proceso. Una vez se determinan las mejores condiciones operacionales para el diseño del bache las cuales son: concentración, caudales de inyección y tiempos de inyección, se procede a ser incluidas en el modelo de simulación para el análisis de los resultados finales.Finalmente, los resultados obtenidos permitieron plantear una metodología para el diseño de baches en procesos de inyección de polímeros con el desarrollo de una herramienta computacional útil para el pre-diseño del bache, la cual involucra modelos analíticos como son: ley de Fick, modelo de Perkins, modelo de Warren, método de Bentsen y modelo de El-Khatib que tienen como base principal los fenómenos de interacción roca-fluidos presentes en el medio poroso y posteriormente empleando simulación numérica de yacimientos como herramienta de validación de los resultados obtenidos.Palabras clave: Inyección de polímeros, bache de polímero, modelos analíticos, simulación numérica, metodología.METHODOLOGY FOR SLUG DESIGNING DURING POLYMER INJECTION PROCESS, TAKING INTO ACCOUNT THE ROCK- FLUID INTERACTION WITHIN THE POROUS MEDIAABSTRACTPolymer Injection is an enhanced recovery process meant to improve conventional water flooding. This technique takes advantage of polymer´s solution viscosity to control fluids formation mobility and generate an uniform reservoir coverage, resulting in a better oil displacement.Due to actual needs of increasing hydrocarbon reserves through production optimization strategies, implementing this process is attractive in water flooding fields where recovery of hydrocarbon has not met expectations. To increase the probability of success, it is critical for the process, designing the right slug to be injected, since the nature of flow through porous media is governed by fluid- rock interaction that may affect flooding efficiency. The pill has to be big enough to withstand loss or change of polymer concentration preserving physical and chemical slug properties during the process. Understanding this phenomenon during design stages is very important to ensure acceptable flow during minimum required time.This paper develops a methodology to design polymer slugs during a chemical injection process based on rock- fluid interactions phenomena in porous media, starting from a computerized tool during pre-design stage, involving analytical models available through a sensitivity analysis of the design parameters and observe behaviours of the polymer concentration on the injected fluid as a function of time and length; and how interaction phenomena within reservoir affects its performance.Additionally, since analytical models do not take into account all diffusion, dispersion and adsorption phenomena on the rock, a simulation model (sector model) was developed on the STARS platform from CMG Ltd. to model chemical injection projects, where obtained results from computerized tools are processed through a sensibility analysis of operational parameters that affect the process. Considering Recovery factor analysis, production rates, water front velocity, flooding efficiency and water cut, the optimized operational conditions can be obtained. Once the best conditions for design concentration, injection rate and time are encountered, the next step is to include them in the simulation model for final analysis.Finally, obtained results allowed stablishing a methodology to design slugs during polymer injection using a computerized tool to pre- design the slug, that involves analytical models such as Fick law, Perkins model, Warren , Bentsen method and El- Khatib model which are based on the rock- fluid interaction within the porous media and finalising with a reservoir numeric simulation to validate the results.Keywords: Polymer injection, polymer slug, analytical models, numeric simulation, methodology

Novel and Efficient Hw-Sw Developments in Millimeter Wave Antenna Measurement Facilities

The aim of this communication is to show recent developments in the field of millimeter-wave antenna test ranges. Measurement facilities are complete systems used to acquire the radiated field by an antenna under test. When operating in millimeter waves, some common implementation principles become simply unaffordable. Manufacturing tolerances, structures computation times and available RF power offered by instrumentation become challenging aspects to cope with in millimeter waves. The developments shown in this paper focus on these issues

Open questions in the social lives of viruses

Social interactions among viruses occur whenever multiple viral genomes infect the same cells, hosts, or populations of hosts. Viral social interactions range from cooperation to conflict, occur throughout the viral world, and affect every stage of the viral lifecycle. The ubiquity of these social interactions means that they can determine the population dynamics, evolutionary trajectory, and clinical progression of viral infections. At the same time, social interactions in viruses raise new questions for evolutionary theory, providing opportunities to test and extend existing frameworks within social evolution. Many opportunities exist at this interface: Insights into the evolution of viral social interactions have immediate implications for our understanding of the fundamental biology and clinical manifestation of viral diseases. However, these opportunities are currently limited because evolutionary biologists only rarely study social evolution in viruses. Here, we bridge this gap by (1) summarizing the ways in which viruses can interact socially, including consequences for social evolution and evolvability; (2) outlining some open questions raised by viruses that could challenge concepts within social evolution theory; and (3) providing some illustrative examples, data sources, and conceptual questions, for studying the natural history of social viruses

Four-channel self-compensating single-slope ADC for space environments

A multichannel high-resolution single-slope analogue-to-digital converter (SS ADC) is presented that automatically compensates for process, voltage and temperature variations, as well as for radiation effects, in order to be used in extreme environmental conditions. The design combines an efficient implementation by using a feedback loop that ensures an inherently monotonic and very accurate ramp generation, with high levels of configurability in terms of resolution and conversion rate, as well as input voltage range. The SS ADC was designed in a standard 0.35 μm CMOS technology. Experimental measurements of the performance and stability against radiation and temperature are presented to verify the proposed approach

A Front-End ASIC for a 3-D Magnetometer for Space Applications by Using Anisotropic Magnetoresistors

This paper presents an application-specific integrated circuit (ASIC) aimed for an alternative design of a digital 3-D magnetometer for space applications, with a significant reduction in mass and volume while maintaining a high sensitivity. The proposed system uses magnetic field sensors based on anisotropic magnetoresistances and a rad-hard mixed-signal ASIC designed in a standard 0.35 μm CMOS technology. The ASIC performs sensor-signal conditioning and analogue-to-digital conversion, and handles calibration tasks, system configuration, and communication with the outside. The proposed system provides high sensitivity to low magnetic fields, down to 3 nT, while offering a small and reliable solution under extreme environmental conditions in terms of radiation and temperature.Ministerio de Ciencia e Innovación AYA2011-29967-C05-05, AYA2009-14212-C05-04, AYA2008-06420-C04-0