Charge fluctuations in the unconventional metallic state of Li0.9Mo6O17

Charge fluctuations in the quasi-one-dimensional material Li0.9Mo6O17 are analyzed based on a multi orbital extended Hubbard model. A charge ordering transition induced by Coulomb repulsion is found with a charge ordering pattern different from a conventional charge density wave driven by Fermi surface nesting. The metallic state displays a characteristic charge collective mode which softens signalling the proximity to the transition. We argue that the strong scattering between electrons generated by these charge order fluctuations can lead to the unconventional metallic state observed above the superconducting transition temperature in Li0.9Mo6O17.Comment: 5 pages, 4 figures, typos corrected and references adde

A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy

New light curves of the gravitationally lensed double quasar Q0957+561 in the gr bands during 2008-2010 include densely sampled, sharp intrinsic fluctuations with unprecedentedly high signal-to-noise ratio. These relatively violent flux variations allow us to very accurately measure the g-band and r-band time delays between the two quasar images A and B. Using correlation functions, we obtain that the two time delays are inconsistent with each other at the 2sigma level, with the r-band delay exceeding the 417-day delay in the g band by about 3 days. We also studied the long-term evolution of the delay-corrected flux ratio B/A from our homogeneous two-band monitoring with the Liverpool Robotic Telescope between 2005 and 2010. This ratio B/A slightly increases in periods of violent activity, which seems to be correlated with the flux level in these periods. The presence of the previously reported dense cloud within the cD lensing galaxy, along the line of sight to the A image, could account for the observed time delay and flux ratio anomalies.Comment: 8 pages, 6 figures, 4 tables, to appear in Astronomy and Astrophysic

La escuela centrada en la comunidad. Un modelo de escuela inclusiva para el siglo XXI

The work offers key theoretical and methodological to respond to the current challenge of developing a school open to the community in the sense of well-known expression "school in the community and the school community" against the anachronism that is the dominance of the model school closed on itself and cutting-rationalist academic. To do so, based on the analysis of the two directions of the educational demand of today's society to school: the academic direction (challenge cultural and scientificprofessional) and trend social (vital challenge-convivial), the structure proposal for action over the following three models: "Schools set by the community", "Education, by and for the community" and "community schools".El trabajo ofrece claves teóricas y metodológicas para responder al reto actual de desarrollar una escuela abierta a la comunidad en el sentido de la conocida expresión “escuela en la comunidad y comunidad en la escuela” frente al anacronismo que significa el predominio del modelo de escuela clausurada sobre sí misma y de corte racionalista academicista. Para ello, a partir del análisis de las dos direcciones de la demanda educativa de la sociedad actual a la escuela: la dirección académica (reto cultural y científicoprofesional) y dirección social (reto vital-convivencial), estructura la propuesta de acción a través de los tres modelos siguientes: “Escuelas configuradas por la comunidad”, “Educación en, por y para la comunidad” y “escuelas comunitarias”

New two-colour light curves of Q0957+561: time delays and the origin of intrinsic variations

We extend the gr-band time coverage of the gravitationally lensed double quasar Q0957+561. New gr light curves permit us to detect significant intrinsic fluctuations, to determine new time delays, and thus to gain perspective on the mechanism of intrinsic variability in Q0957+561. We use new optical frames of Q0957+561 in the g and r passbands from January 2005 to July 2007. These frames are part of an ongoing long-term monitoring with the Liverpool robotic telescope. We also introduce two photometric pipelines that are applied to the new gr frames of Q0957+561. The transformation pipeline incorporates zero-point, colour, and inhomogeneity corrections to the instrumental magnitudes, so final photometry to the 1-2% level is achieved for both quasar components. The two-colour final records are then used to measure time delays. The gr light curves of Q0957+561 show several prominent events and gradients, and some of them (in the g band) lead to a time delay between components of 417 +/- 2 d (1 sigma). We do not find evidence of extrinsic variability in the light curves of Q0957+561. We also explore the possibility of a delay between a large event in the g band and the corresponding event in the r band. The gr cross-correlation reveals a time lag of 4.0 +/- 2.0 d (1 sigma; the g-band event is leading) that confirms a previous claim of the existence of a delay between the g and r band in this lensed quasar. The time delays (between quasar components and between optical bands) from the new records and previous ones in similar bands indicate that most observed variations in Q0957+561 (amplitudes of about 100 mmag and timescales of about 100 d) are very probably due to reverberation within the gas disc around the supermassive black hole.Comment: 13 pages, 9 figures. Accepted for publication in A&

Manejo del material de siembra de yuca (Manihot esculenta Crantz)

Several cassava trials were planted at CIAT to study the effect of the maturity of stem cuttings, depth of planting, cutting length, planting position and the angle of the cut on root yield. Cuttings from the top and middle part of vigorous 1-yr-old plants produced greater than root yields than those proceeding from the lower part of the plant or from older stem parts. Cuttings planted vertically 10, 20 and 30 cm deep do not affect the yield but do affect root distribution, the no. of roots/plant and the difficulty of harvesting; planting at 10 cm in depth was the most adequate. Twenty-cm long, selected and treated cuttings gave slightly higher yields than 40 or 60 cm ones. Cuttings placed vertically assure more rapid emergence, greater than percentage of germination, greater than yields and prevent lodging in comparison to those planted in a horizontal or inclined position. When the stems were cut rectangularly or bevel-edged, different rooting systems were produced; the former produced roots with a more uniform distribution; nevertheless, yield was not affected. Vertical planting, either with a straight or bevel-edged cut, gave greater than yields than horizontal planting. To obtain max yields, planting material should be selected from the middle part of mature, vigorous plants, cut at right angles 20 cm long and planted vertically 10 cm deep. (AS-CIAT)Se sembraron varios ensayos de yuca en el CIAT para estudiar el efecto de la madurez de las estacas, profundidad de siembra, longitud de la estaca, posicion de siembra y angulo de corte de la misma, en el rendimiento de las raices. Las estacas de la parte media y superior de plantas vigorosas de un ano de edad produjeron mayores rendimientos de raices que aquellas provenientes de la parte baja de la planta o de estacas viejas. Las estacas sembradas verticalmente a 10, 20 y 30 cm de profundidad no influyen en el rendimiento, pero afectan la distribucion de raices, el numero de raices/planta y la facilidad de cosecha; la siembra a 10 cm de profundidad fue la mas adecuada. Las mayores estacas de 20 cm de largo seleccionadas y tratadas dieron rendimientos ligeramente mayores que las de 40 o 60 cm. La siembra vertical de las estacas aseguro una emergencia mas rapida, un mayor porcentaje de germinacion, mayores rendimientos y previno el volcamiento de las plantas, en comparacion con la posicion horizontal o inclinada. El corte de la estaca en forma rectangular o en bisel produjo diferentes sistemas de enraizamiento; el primero produce raices mas uniformemente distribuidas; sin embargo, no afecta el rendimiento. La siembra vertical, ya sea con angulo de corte recto o en bisel, da mayores rendimientos que la siembra horizontal. Para obtener los rendimientos maximos, el material de siembra se debe seleccionar de la parte media de plantas vigorosas maduras, cortado en un angulo recto, en trozos de 20 cm de largo y sembrado verticalmente a 10 cm de profundidad. (RA-CIAT

Three dimensional fluid-kinetic model of a magnetically guided plasma jet

A fluid-kinetic model of the collisionless plasma row in a convergent-divergent magnetic nozzle is presented. The model combines the leading-order Vlasov equation and the fluid continuity and perpendicular momentum equation for magnetized electrons, and the fluid equations for cold ions, which must be solved iteratively to determine the self-consistent plasma response in a three-dimensional magnetic field. The kinetic electron solution identifies three electron populations and provides the plasma density and pressure tensor. The far downstream asymptotic behavior shows the anisotropic cooling of the electron populations. The fluid equations determine the electric potential and the fluid velocities. In the small ion-sound gyroradius case the solution is constructed one magnetic line at a time. In the large ion-sound gyroradius case, ion detachment from magnetic lines makes the problem fully three-dimensional.This work was supported by National R&D Plan (Grant ESP2016-75887) from the Gobierno de España. Jesús Ramos thanks the financial sponsorship of the Chair of Excellence award granted by UC3M and Banco de Santander

Analysis of Indoor Radon Distribution Within a Room By Means of Computational Fluid Dynamics (CFD) Simulation

Radon gas is recognized by international organizations such as the United States Environmental Protection Agency (US-EPA) as the main contributor of radiation environmental to which human beings are exposed. Therefore, the evaluation of indoor radon concentration is a matter of public interest. The emanation and the income of the gas inside a room will generate a negative impact on the quality of the air when the place is not properly ventilated. Understanding how this gas will be distributed inside the room will allow to predict the spatial and temporal variations of radon levels and identify these parameters will provide important information that researchers can be used for calculate radiation dose exposure. Consequently, this studies can prevent a health risk for the people that live or work within the room. Currently, several researchers use the technique called Computational Fluid Dynamics (CFD) to simulate the distribution of gas radon, making use of the various commercial programs that exist in the market. In this work, three simulations were developed in rooms that have a similar geometry but different dimensions, in order to observe how the gas is distributed inside a closed space and to analyze how this distribution varies when the volume of the place is increased. The results show that as the volume of the site increases the radon is mitigated more rapidly and therefore has lower levels of concentration of this gas, as long as the level of radon emanation is kept constant