Convergence and density results for parabolic quasi-linear Venttsel’ problems in fractal domains

In this paper we study a quasi-linear evolution equation with nonlinear dynamical boundary conditions in a three dimensional fractal cylindrical domain Q, whose lateral boundary is a fractal surface S. We consider suitable approximating pre-fractal problems in the corresponding pre-fractal varying domains. After proving existence and uniqueness results via standard semigroup approach, we prove density results for the domains of energy functionals defined on Q and S. Then we prove that the pre-fractal solutions converge in a suitable sense to the limit fractal one via the Mosco convergence of the energy functionals

Control Infrastructure for a Pulsed Ion Accelerator

We report on updates to the accelerator controls for the Neutralized Drift Compression Experiment II, a pulsed induction-type accelerator for heavy ions. The control infrastructure is built around a LabVIEW interface combined with an Apache Cassandra backend for data archiving. Recent upgrades added the storing and retrieving of device settings into the database, as well as ZeroMQ as a message broker that replaces LabVIEW's shared variables. Converting to ZeroMQ also allows easy access via other programming languages, such as Python

The Isotropic Radio Background and Annihilating Dark Matter

Observations by ARCADE-2 and other telescopes sensitive to low frequency radiation have revealed the presence of an isotropic radio background with a hard spectral index. The intensity of this observed background is found to exceed the flux predicted from astrophysical sources by a factor of approximately 5-6. In this article, we consider the possibility that annihilating dark matter particles provide the primary contribution to the observed isotropic radio background through the emission of synchrotron radiation from electron and positron annihilation products. For reasonable estimates of the magnetic fields present in clusters and galaxies, we find that dark matter could potentially account for the observed radio excess, but only if it annihilates mostly to electrons and/or muons, and only if it possesses a mass in the range of approximately 5-50 GeV. For such models, the annihilation cross section required to normalize the synchrotron signal to the observed excess is sigma v ~ (0.4-30) x 10^-26 cm^3/s, similar to the value predicted for a simple thermal relic (sigma v ~ 3 x 10^-26 cm^3/s). We find that in any scenario in which dark matter annihilations are responsible for the observed excess radio emission, a significant fraction of the isotropic gamma ray background observed by Fermi must result from dark matter as well.Comment: 11 pages, 6 figure

Communities and regularities in the behavior of investment fund managers

We analyze a large microlevel dataset on the full daily portfolio holdings and exposures of 22 complex investment funds to shed light on the behavior of professional investment fund managers. We introduce a set of quantitative attributes that capture essential distinctive features of manager allocation strategies and behaviors. These characteristics include turnover, attitude toward hedging, portfolio concentration, and reaction to external events, such as changes in market conditions and flows of funds. We find the existence and stability of three main investment attitude profiles: conservative, reactive, and proactive. The conservative profile shows low turnover and resilience against external shocks; the reactive one is more prone to respond to market condition changes; and members of the proactive profile frequently adjust their portfolio allocations, but their behavior is less affected by market conditions. We find that exogenous shocks temporarily alter this configuration, but communities return to their original state once these external shocks have been absorbed and their effects vanish

Myoblasts and macrophages share molecular components that contribute to cell–cell fusion

Cell–cell fusion is critical to the normal development of certain tissues, yet the nature and degree of conservation of the underlying molecular components remains largely unknown. Here we show that the two guanine-nucleotide exchange factors Brag2 and Dock180 have evolutionarily conserved functions in the fusion of mammalian myoblasts. Their effects on muscle cell formation are distinct and are a result of the activation of the GTPases ARF6 and Rac, respectively. Inhibition of ARF6 activity results in a lack of physical association between paxillin and β1-integrin, and disruption of paxillin transport to sites of focal adhesion. We show that fusion machinery is conserved among distinct cell types because Dock180 deficiency prevented fusion of macrophages and the formation of multinucleated giant cells. Our results are the first to demonstrate a role for a single protein in the fusion of two different cell types, and provide novel mechanistic insight into the function of GEFs in the morphological maturation of multinucleated cells

Response of common bean (Phaseolus vulgaris L.) to nitrogen, phosphorus and rhizobia inoculation across variable soils in Zimbabwe

Open Access Article; Published online: 18 Aug 2018Common bean is an important crop with potential to curb malnutrition in poor Sub-Saharan African populations. Yields of common bean (Phaseolus vulgaris L.) are, however poor, limited by low soil phosphorus (P), nitrogen (N) and poor biological N2-fixation. On-farm experiments were carried out to study the effect of N, P and rhizobia inoculation on common bean yield and yield components during the 2014/2015 and 2015/2016 cropping seasons in Eastern Zimbabwe. Experiments were conducted on five farmers’ fields located in two agroecologies; three fields were considered to be degraded with soil organic carbon (SOC)  7 g kg−1 and available P > 15 mg kg−1. Two common bean varieties (Gloria and NUA45) were tested in a split-plot arranged in randomized complete block design. The main plot factor was the combination of N (0 and 40 kg ha−1) and P (0 and 20 kg ha−1), and the sub-plot factors were variety (Gloria and NUA 45) and inoculation with Rhizobium tropici strain CIAT899 (+/− inoculum). At planting, both N and P were applied at 20 kg ha−1, with an additional 20 kg ha−1 N top dressing applied at flowering. Analysis of variance indicated common bean did not respond to rhizobia inoculation (P > 0.05) whilst P significantly increased the number of nodules and active nodules per plant (P < 0.001), and grain yield. Application of 40 kg ha−1 N significantly increased the number of pods per plant, number of seeds per pod, and grain yields. A significant NP interaction was only observed on grain yield for non-degraded soils. Co-application of N and P in non-degraded sites increased grain yields from 0.27 to 1.48 Mg ha−1during the first season and from 0.37 to 2.09 Mg ha−1during the second season. On degraded sites, NP application resulted in uninspiring grain yield gains of 0.09 to 0.19 Mg ha−1 during the first season, and from 0.16 to 0.28 Mg ha−1 in the second season. In general, effects of N or P were not significantly different, suggesting that farmers could invest in either of these nutrients for increased common bean grain yields. Strategically, P investments would be more logical as residual P effects to rotational cereals improve overall cropping system performance. The response of common bean to inoculation in Zimbabwe still needs to be widely investigated for these and other varieties

VLBA determination of the distance to nearby star-forming regions I. The distance to T Tauri with 0.4% accuracy

In this article, we present the results of a series of twelve 3.6-cm radio continuum observations of T Tau Sb, one of the companions of the famous young stellar object T Tauri. The data were collected roughly every two months between September 2003 and July 2005 with the Very Long Baseline Array (VLBA). Thanks to the remarkably accurate astrometry delivered by the VLBA, the absolute position of T Tau Sb could be measured with a precision typically better than about 100 micro-arcseconds at each of the twelve observed epochs. The trajectory of T Tau Sb on the plane of the sky could, therefore, be traced very precisely, and modeled as the superposition of the trigonometric parallax of the source and an accelerated proper motion. The best fit yields a distance to T Tau Sb of 147.6 +/- 0.6 pc. The observed positions of T Tau Sb are in good agreement with recent infrared measurements, but seem to favor a somewhat longer orbital period than that recently reported by Duchene et al. (2006) for the T Tau Sa/T Tau Sb system.Comment: 24 pages, 3 pages, AASTEX format, accepted for publication in Ap

Propuesta de evaluación como proceso de revisión metodológica del aprendizaje. Uso de la rúbrica

Fil: Mansilla, Lilyán del V. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Fil: Regis, Liliana B. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.El aprendizaje es el núcleo fundamental de la acción educativa. Valorar el aprendizaje del alumno en el proceso y en las competencias alcanzadas constituye uno de los aspectos más relevantes de la enseñanza. Desde la perspectiva de la evaluación formadora, multicultural, participativa y consensuada, centrada en el aprendizaje, se consideran diferentes técnicas e instrumentos. Estas herramientas de evaluación se definen como procedimientos y actividades realizadas por los alumnos con el fin de recoger información y medir el logro de los aprendizajes esperados en una determinada área del conocimiento. La rúbrica o matriz es un instrumento de evaluación que consiste en una tabla de doble entrada donde se establecen niveles de desempeños, logros de los objetivos y competencias de los estudiantes, sobre aspectos determinados y con criterios específicos. Las rúbricas son guías precisas que valoran los aprendizajes y productos realizados. El presente trabajo permite conocer la experiencia del uso de la rúbrica como instrumento de evaluación en el trabajo práctico de campo de la asignatura Geomorfología, de la carrera de Geología de la Universidad Nacional de Córdoba, República Argentina. El ajuste de la metodología se llevó a cabo durante el primer y segundo año de su aplicación, con resultados muy satisfactorios a lo largo de nueve años.La importancia en el uso de este instrumento de evaluación, ha sido eje fundamental en nuestra experiencia, consistió en constituir un elemento patrón y de normalización cuando son varios los docentes involucrados en las acciones de evaluación de una determinada materia o actividad práctica. La rúbrica permitió a los docentes consensuar y establecer criterios y parámetros de evaluación, y alcanzar un valor mínimo de subjetividad personal en una tarea colectiva.La importancia de esta propuesta de evaluación radica en la coincidencia de los resultados obtenidos cuando esaplicada por distintos docentes. Se reconoce la utilidad y el potencial de la rúbrica, no sólo como instrumento de evaluación sino también como proceso de revisión metodológica del aprendizaje.Considerando la trascendencia de evaluar los conocimientos y habilidades desarrollados en un trabajo Prácticode Campo, se pretende mediante la presente publicación, difundir una herramienta que agiliza y optimiza la tarea de evaluación de una actividad habitual en la carrera.Fil: Mansilla, Lilyán del V. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Fil: Regis, Liliana B. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Otras Ciencias de la Educació