Completing the picture of the Roper resonance

We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the proton's radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleon's first radial excitation is the Roper resonance. It consists of a core of three dressed-quarks, which expresses its valence-quark content and whose charge radius is 80% larger than the proton analogue. That core is complemented by a meson cloud, which reduces the observed Roper mass by roughly 20%. The meson cloud materially affects long-wavelength characteristics of the Roper electroproduction amplitudes but the quark core is revealed to probes with $Q^2 \gtrsim 3 m_N^2$.Comment: 6 pages, 3 figure

Phytochrome B integrates light and temperature signals in Arabidopsis

Ambient temperature regulates many aspects of plant growth and development, but its sensors are unknown. Here, we demonstrate that the phytochrome B (phyB) photoreceptor participates in temperature perception through its temperature-dependent reversion from the active Pfr state to the inactive Pr state. Increased rates of thermal reversion upon exposing Arabidopsis seedlings to warm environments reduce both the abundance of the biologically active Pfr-Pfr dimer pool of phyB and the size of the associated nuclear bodies, even in daylight. Mathematical analysis of stem growth for seedlings expressing wild-type phyB or thermally stable variants under various combinations of light and temperature revealed that phyB is physiologically responsive to both signals. We therefore propose that in addition to its photoreceptor functions, phyB is a temperature sensor in plants

Free and underfit-scavenger river dynamics dominate the large Amazonian Pacaya-Samiria wetland structure

The Peruvian Amazon is known for harboring the greatest biodiversity on the planet, with a world record for biodiversity per unit area. Previous studies suggested that the high ecological value depends on correlations between ecosystem functionality and seasonal inundation control vegetation patches. However, the knowledge on how river morphodynamics and its complex erosion-depositional processes influence the aquatic mosaic and fishing activity in the region is still incipient. This study examines the hydrogeomorphology of the Peruvian tropical wetland of Pacaya Samiria, located in Western Amazonia, and its role in the distribution of aquatic habitats. By using remote sensing techniques, the hydrogeomorphological connectivity that bounds the Pacaya Samiria National Reserve is characterized by ancient to modern river processes. Additionally, river signatures developed by the Ucayali, Marañon, Huallaga, Pacaya, and Samiria Rivers overlap with fish extraction and dominant vegetation to describe how geomorphology is associated with the spatial distribution of fishing zones. Results indicated that paleochannels regulate wetland drainage within the Ucamara Depression, supporting stational water stagnation, vegetation cover, and formation of carbon rich detritus, relevant aspects to understand fish traits. Moreover, the Ucayali River dominates river dynamics in the Pacaya Samiria wetland, thus playing a pivotal role in shaping the complexity of streams and lakes. Furthermore, underfit-scavenger meandering rivers are observed in areas where paleochannels from large rivers are found. A geomorphological characterization of drainage patterns in freshwater environments, such as Amazonian wetlands, is crucial to develop sound management strategies. This methodological approach is expected to support decision-making in conservation actions in Amazonian environments based on understanding wetland connectivity and hydrogeomorphological behavior and their influence on commercial fisheries

Shearographic System for Dynamic Analysis of Materials under Heat Stress

Los sistemas de shearografía son herramientas para el control e inspección de fallas e imperfecciones estructurales en diferentes tipos de aplicaciones industriales, automotrices y aeronáuticas. Se basan en la correlación digital de dos frentes de onda de patrones de speckle en dos estados de interés: con y sin carga. La técnica tiene la cualidad especial de ser autoreferenciada en sus frentes de onda y por tanto es muy robusta frente a perturbaciones ambientales. Se presenta un sistema shearografía en el cual se puede analizar el comportamiento dinámico de los esfuerzos que sufre un material en función de cambios en temperatura a lo largo de todo el proceso de carga térmica.Shearography is a tool for monitoring and inspecting of structural flaws and imperfections in different types of industrial, automotive and aeronautics applications. It is based on digital correlation of two speckle patterns in two states of interest: with and without load. The technique has the special quality of being very robust against environmental disturbances. We present a shearographic system to analyze the dynamic behavior of the strain that suffers a material in response to changes in temperature throughout the thermal load process

Measuring the speed of light and the moon distance with an occultation of Mars by the Moon: a Citizen Astronomy Campaign

In July 5th 2014 an occultation of Mars by the Moon was visible in South America. Citizen scientists and professional astronomers in Colombia, Venezuela and Chile performed a set of simple observations of the phenomenon aimed to measure the speed of light and lunar distance. This initiative is part of the so called "Aristarchus Campaign", a citizen astronomy project aimed to reproduce observations and measurements made by astronomers of the past. Participants in the campaign used simple astronomical instruments (binoculars or small telescopes) and other electronic gadgets (cell-phones and digital cameras) to measure occultation times and to take high resolution videos and pictures. In this paper we describe the results of the Aristarchus Campaign. We compiled 9 sets of observations from sites separated by distances as large as 2,500 km. We achieve at measuring the speed of light in vacuum and lunar distance with uncertainties of few percent. The goal of the Aristarchus Campaigns is not to provide improved values of well-known astronomical and physical quantities, but to demonstrate how the public could be engaged in scientific endeavors using simple instrumentation and readily available technological devices. These initiatives could benefit amateur communities in developing countries increasing their awareness towards their actual capabilities for collaboratively obtaining useful astronomical data. This kind of exercises would prepare them for facing future and more advanced observational campaigns where their role could be crucial.Comment: 21 pages, 10 figures, 3 tables. An abridged and more general version of this paper was accepted for publication in Communicating Astronomy with the Public Journal (http://www.capjournal.org

Three-dimensional Josephson-junction arrays in the quantum regime

We study the quantum phase transition properties of a three-dimensional periodic array of Josephson junctions with charging energy that includes both the self and mutual junction capacitances. We use the phase fluctuation algebra between number and phase operators, given by the Euclidean group E_2, and we effectively map the problem onto a solvable quantum generalization of the spherical model. We obtain a phase diagram as a function of temperature, Josephson coupling and charging energy. We also analyze the corresponding fluctuation conductivity and its universal scaling form in the vicinity of the zero-temperature quantum critical point.Comment: 9 pages, LATEX, three PostScript figures. Submitted to Phys. Rev. Let

Protocolo experimental para la evaluación de microemulsiones que modifican la mojabilidad en el medio poroso. Aplicación a campos colombianos

Las reservas de crudo liviano son cada vez más escasas, a diferencia de los descubrimientos de crudo pesado, razón por lo cual se ha enfocado la atención en este tipo de hidrocarburos. Colombia tiene un gran potencial de crudo pesado, sobre todo en las zonas de la Cuenca de los Llanos Orientales (Campos: Rubiales, Castilla, Chichimene, Apiay, Suria), cuyo desarrollo en los últimos años, ha logrado que el 60% de la producción nacional este asociada a este tipo de recurso. La producción de crudo pesado no es fácil, una de las principales dificultades es la alta viscosidad del hidrocarburo, lo cual origina una baja movilidad del mismo y una temprana producción de agua en yacimientos con acuíferos activos. Una de las técnicas más utilizadas para incrementar la productividad en los yacimientos de crudos pesados es la estimulación matricial de pozos, a partir de la cual se pueden modificar las curvas de permeabilidad relativa (alteración de la humectabilidad) y así mejorar la movilidad de estos crudos. Sin embargo es crucial la comprensión de la mojabilidad de la formación para optimizar la recuperación de petróleo. Suponer que una formación es mojable por agua, cuando en realidad no lo es, puede ocasionar daños irreversibles en el yacimiento. Por lo anterior, el presente estudio se centró en desarrollar e implementar un protocolo a nivel de laboratorio, para evaluar tratamientos de estimulación matricial base agua, que tuvieran la capacidad de invertir la mojabilidad natural (generalmente al crudo, debido a la alta afinidad entre el crudo y minerales de roca del yacimiento), hacia una mojabilidad al agua, que conduce a un mejoramiento de la permeabilidad relativa al crudo. El protocolo experimental fue implementado a nivel de laboratorio en el campo Castilla (cuenca de los llanos orientales en Colombia) y se enfocó en tres grandes etapas. 1. Etapa 1: Caracterización básica de fluidos de formación 2. Etapa 2: Evaluación fluido-fluido y comportamiento reológico de fluidos de formación Vs Tratamientos químicos. 3. Etapa 3: Evaluación del efecto sobre la humectabilidad (modificación de ángulos de contacto y permeabilidad relativa). Las principales conclusiones y recomendaciones obtenidas en este estudio son las siguientes: 1. Se desarrolló un protocolo experimental adecuado para la evaluación de microemulsiones y/o aditivos mejoradores de movilidad. 2. La implementación del protocolo permitió seleccionar el mejor tratamiento de alteración de la humectabilidad para el campo Castilla. 3. En la preferencia de la mojabilidad del yacimiento, tienen incidencia: los componentes del petróleo, la química de la salmuera, la superficie mineral, la temperatura, la presión, la tensión interfacial de los fluidos, la presión capilar y la historia de saturación del yacimiento.Reserves of light crude oil are decreasing in contrast to the discoveries of heavy crude which is why attention has been focused on this type of hydrocarbons. Colombia has a high potential in the heavy-crude development especially in the areas of the Llanos Orientales Basin (Campos: Rubiales, Castilla, Chichimene, Apiay, Suria) which have been produced in recent years to achieve that the 60% of the national production is associated with this type of resource. Heavy-oil production is not easy due to its high viscosity which causes low oil mobility and early water production in reservoirs with active aquifers. One of the main techniques used to increase productivity in heavy crude oil fields is the matrix stimulation of wells through the injection of treatments that positively alter the relative permeability curves (alteration of wettability) and thus improve the mobility of these crude oils. However, understanding the formation wettability is essential to optimize oil recovery. To assume that a formation is wettable by water, when in reality it is not, can cause irreversible damage to the reservoir. Therefore, the current study focused on developing and implementing a protocol at the laboratory level, to evaluate water-based matrix stimulation treatments that have ability to reverse natural oil wettability (generally to the oil, due to high affinity between oil and rock minerals of reservoir) towards water wettability, which leads to an improvement of relative permeability to crude oil. The experimental protocol was implemented at laboratory level for the Castilla Oilfield (Llanos Orientales basin in Colombia) and focused on three major stages. 1. Stage 1: Basic characterization of treatment fluids. 2. Stage 2: Fluid-fluid evaluation and rheological behavior of formation fluids Vs. Chemical treatments. 3. Stage 3: Evaluation of effect on wettability (modification of contact angles and relative permeability). The main conclusions and recommendations obtained in this study are the following: 1. A suitable experimental protocol was developed for evaluation of microemulsions and / or mobility enhancing additives. 2. Implementation of protocol allowed selecting the best treatment of alteration of wettability for the Castilla oilfield. 3. The components of the oil, the brine chemistry, the mineral surface, the temperature, the pressure, the interfacial tension, the capillary pressure, the saturation history of reservoir, among other properties have an impact on the reservoir’s wettability

Evaluación de la calidad y el impacto del ambiente acuático del río higueras en la provincia de Huánuco – 2014

Natural surface water is one of the most widespread, abundant substances on Earth. It is an integralpart of most living things and is present in allowable amount. The naturally pure drinking water isessential for life; the great civilizations have flourished near adequate supplies of the liquid of life.Riparian vegetation plays Higueras river habitat and ecosystem functions. Influences on hydrology,soil science, physicochemical, chemical and microbiological water, so it is relevant in productivity andperformance, regulates temperature, filtering, retaining nutrients and providing habitat for aquatic communities. The study made some approaches on quality and perceived negative impact on waterquality conditions by measuring various physical, chemical and microbiological parameters. Gradientas described sampling stations throughout the course of the channels. The results indicate highpollution and high negative impacts, with the highest incidence in sites close proximity to coastalsettlements channels. The variables which show excessively high values such sites are the accountof bacteria, coliforms and detergent concentrations, physico-chemical parameters. The temporarynature of the water increases the severity of concentration of some contaminants. It is also remarkablethe impact of the deterioration of the natural quality of the physical environment all the way fromsurface waters of the river, mainly due to agricultural activities, extraction of construction materialsand domestic wastewater discharges affecting the biota aquatic. The results indicate that since thewater stations up even still have low impact on quality, while at stations downstream (Season 4, 5, 6,7, 8, 9, 10) are at high risk for contamination, which is confirms strong electric conductivity, turbidity,eutrophication and disappearance of aquatic life becoming to be a dead river, organoleptic, physicalchemical parameters, microbiological very high concentrations and the presence of ammonia andmineral salts that characterize hard water inadmissible for loved alive and human consumption.Las aguas superficiales naturales es una de las sustancias más difundidas, abundantes en PlanetaTierra. Es parte integrante de la mayoría de los seres vivientes y está presente en cantidadpermisibles. El agua natural pura y potable es fundamental para la vida; las grandes civilizaciones hanflorecido cerca de abastecimientos adecuados de ese líquido de la vida. La vegetación ribereña delrío Higueras desempeña funciones de hábitat y ecosistemas. Influye sobre la hidrología, edafología,físico- químico, químico y microbiológico de las aguas, por lo que es relevante en productividad yfuncionamiento, regula la temperatura, filtrando, reteniendo nutrientes y otorgando hábitat a lascomunidades acuáticas. El estudio realizó unas aproximaciones sobre la calidad y su impacto negativopercibidas sobre condiciones de calidad del agua mediante la determinación de varios parámetrosfísico-químicos y microbiológicos. El gradiente de muestreos en estaciones ya descritos por todo elcurso de los cauces. Los resultados indican grado alto de contaminación e impactos negativos altos,con mayor incidencia en los sitios de asentamientos humanos muy próximos a los cauces ribereños.Las variables analizadas las que muestran valores excesivamente elevadas en dichos sitios, son lacuenta de bacterias, coliformes y las concentraciones de detergentes, parámetros físico- químicos. Elcarácter temporal de las aguas incrementa la gravedad de concentración de algunos contaminantes.Asimismo, es notable el impacto del deterioro de la calidad natural del medio físico en todo eltrayecto de las aguas superficiales del río debido, principalmente, a las actividades agropecuarias,extracción de materiales de construcción y vertidos de aguas servidas domesticas que afectan a labiota acuática. Los resultados indican que desde las estaciones aguas arriba aun todavía presentanbajo impacto en calidad, mientras en las estaciones aguas abajo (estación 4, 5, 6, 7, 8, 9, 10) sonde alto riesgo por la contaminación, lo cual se ratifica con fuerte conductividad eléctrica, turbidez,eutrofización y desaparición de seres vivos acuáticos tornándose a ser un río muerto, parámetrosorganolépticos, físico-químicos, microbiológicos muy altos y la presencia de concentraciones deamoníaco y sales minerales que caracterizan agua dura inadmisibles para los seres vivos y consumohumano

Carbon and Oxygen Galactic Gradients: Observational Values from HII Region Recombination Lines

We present results of deep echelle spectrophotometry of eight Galactic HII regions located at Galactocentric distances between 6.3 and 10.4 kpc. The data have been taken with the Very Large Telescope (VLT) Ultraviolet Echelle Spectrograph (UVES) in the 3100 to 10360 A range. We have derived C++ and O++ abundances from recombination lines for all the objects, as well as O+ abundances from this kind of lines for three of the nebulae. The intensity of recombination lines is almost independent of the assumed electron temperature as well as of the possible presence of spatial temperature variations or fluctuations inside the nebulae. These data allow the determination of the gas-phase C and O abundance gradients of the Galactic disk, of paramount importance for chemical evolution models. This is the first time the C gradient is derived from such a large number of HII regions and for such a wide range of Galactocentric distances. Abundance gradients are found of the form $\Delta$log(O/H) = -0.044$\pm$0.010 dex kpc^-1, $\Delta$log(C/H) = -0.103$\pm$0.018 dex kpc^-1, and $\Delta$log(C/O) = -0.058$\pm$0.018 dex kpc^-1.Comment: 13 pages, 2 tables, 2 figures. Published in ApJ Letters, 618, L9

Organ-specific COP1 control of BES1 stability adjusts plant growth patterns under shade or warmth

Under adverse conditions such as shade or elevated temperatures, cotyledon expansion is reduced and hypocotyl growth is promoted to optimize plant architecture. The mechanisms underlying the repression of cotyledon cell expansion remain unknown. Here, we report that the nuclear abundance of the BES1 transcription factor decreased in the cotyledons and increased in the hypocotyl in Arabidopsis thaliana under shade or warmth. Brassinosteroid levels did not follow the same trend. PIF4 and COP1 increased their nuclear abundance in both organs under shade or warmth. PIF4 directly bound the BES1 promoter to enhance its activity but indirectly reduced BES1 expression. COP1 physically interacted with the BES1 protein, promoting its proteasome degradation in the cotyledons. COP1 had the opposite effect in the hypocotyl, demonstrating organ-specific regulatory networks. Our work indicates that shade or warmth reduces BES1 activity by transcriptional and post-translational regulation to inhibit cotyledon cell expansion.Peer reviewe