A nanoflare based cellular automaton model and the observed properties of the coronal plasma

We use the cellular automaton model described in L\'opez Fuentes \& Klimchuk (2015, ApJ, 799, 128) to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields, produces nanoflares of varying frequency with respect to the plasma cooling time. We compare the results of the model with active region (AR) observations obtained with the Hinode/XRT and SDO/AIA instruments. The comparison is based on the statistical properties of synthetic and observed loop lightcurves. Our results show that the model reproduces the main observational characteristics of the evolution of the plasma in AR coronal loops. The typical intensity fluctuations have an amplitude of 10 to 15\% both for the model and the observations. The sign of the skewness of the intensity distributions indicates the presence of cooling plasma in the loops. We also study the emission measure (EM) distribution predicted by the model and obtain slopes in log(EM) versus log(T) between 2.7 and 4.3, in agreement with published observational values.Comment: Paper 2 of 2: Model comparison with observations. Accepted for publication in Ap

Evidence of Twisted flux-tube Emergence in Active Regions

Elongated magnetic polarities are observed during the emergence phase of bipolar active regions (ARs). These extended features, called magnetic tongues, are interpreted as a consequence of the azimuthal component of the magnetic flux in the toroidal flux-tubes that form ARs. We develop a new systematic and user-independent method to identify AR tongues. Our method is based on determining and analyzing the evolution of the AR main polarity inversion line (PIL). The effect of the tongues is quantified by measuring the acute angle [ tau] between the orientation of the PIL and the direction orthogonal to the AR main bipolar axis. We apply a simple model to simulate the emergence of a bipolar AR. This model lets us interpret the effect of magnetic tongues on parameters that characterize ARs ( e.g. the PIL inclination and the tilt angles, and their evolution). In this idealized kinematic emergence model, tau is a monotonically increasing function of the twist and has the same sign as the magnetic helicity. We systematically apply our procedure to a set of bipolar ARs that were observed emerging in line-of-sight magnetograms over eight years. For most of the cases studied, the tongues only have a small influence on the AR tilt angle since tongues have a much lower magnetic flux than the more concentrated main polarities. From the observed evolution of tau, corrected for the temporal evolution of the tilt angle and its final value when the AR is fully emerged, we estimate the average number of turns in the subphotospherically emerging flux-rope. These values for the 41 observed ARs are below unity, except for one. This indicates that subphotospheric flux-ropes typically have a low amount of twist, i.e. highly twisted flux-tubes are rare. Our results demonstrate that the evolution of the PIL is a robust indicator of the presence of tongues and constrains the amount of twist in emerging flux-tube

Analysis of K-Ras Nuclear Expression in Fibroblasts and Mesangial Cells

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al[Background]: Ras GTPases are considered cytoplasmic proteins that must be localized to cell membranes for activation, and there are few evidences of the presence of any Ras isoform in nuclei of eukaryotic cells. [Methodology/Principal Findings]: Using conventional antibodies and inmunocytochemistry, differential centrifugation and western blot, we have observed the putative presence of K-Ras isoform in the nuclei of fibroblasts and mesangial cells. In order to avoid cross-reactions with other Ras isoforms, and using antibodies against K-Ras (R-3400, H3845-M01, sc-30) or pan-Ras (05-516, OP40) in cells that only expressed the K-Ras isoform (fibroblasts obtained from H-ras−/−,N-ras−/− mice) we also detected some nuclear positive expression. To further probe the identity of nuclear K-Ras, we have generated K-Ras knockout (K-ras−/−) embrionary fibroblasts by mating of K-ras+/− heterozygote mice. Using specific antibodies, only H- and N-Ras isoforms were observed in the cytoplasm of K-ras−/− fibroblasts. However, both K-Ras4A and K-Ras4B positive signals were detected by immunocytochemistry and Western blot with two commercial antibodies (sc-522 and sc-521 against each isoforms, respectively) in both cytoplasm and nuclei from K-ras−/− fibroblasts. [Conclusions/Significance]: We show that the presence of K-Ras4B in fibroblast nuclei, already described by other authors, is probably due to a cross-reaction of the antibody with an undetermined nucleolar protein. Although this study also shows the possible nuclear expression of K-Ras isoform in fibroblasts or in mesangial cells, it also reveals the importance of being cautious in these studies about distribution of protein isoforms due to some important limitations imposed by the unspecificity of the antibodies or contaminations in cellular preparations.This work was supported by grants from Instituto de Salud Carlos III (Ministerio de Sanidad y Consumo, CP03/00094, PI041817, PI021570 and C03/10), Comisión Interministerial de Ciencia y Tecnologí­a (BFU-2004-00285/BFI; SAF2003-04177), and Junta de Castilla y León (SA001/C05; SA029A05; GRS 167/A/07 and excellence group GR100).Peer reviewe

CONCEPCIONES DE LOS PROFESORES DE EDUCACIÓN SECUNDARIA SOBRE EVALUACIÓN

Con el presente trabajo pretendemos hacer una conceptualización del término concepción. Tradicionalmente, las concepciones han sido consideradas por los investigadores como un constructo que engloba el conocimiento personal que los seres humanos poseen. Este término no es exclusivo, en el campo educativo el término concepción coexiste con términos tales como representación, creencias, ideas,teorías personales, actitudes, perspectivas.... Las concepciones de los sujetos se gestan sobre la base de la interacción de tres elementos: la naturaleza bio-antropológica, es decir, el proceso evolutivo seguido como especie y su influencia en el conocimiento; los aspectos históricos que permiten conservar y transmitir nuestras experiencias pasadas; el conjunto de elementos derivados de nuestra particularidad psicológica. En la segunda parte del trabajo realizamos un estudio empírico para detectar cuáles son las concepciones de los profesores respecto a una serie de tópicos: qué evaluar, cuándo evaluar, cómo debe evaluarse, cómo mejorar la evaluación, qué es evaluar... Para esto, se realizaron entrevistas semiestructuradas a profesores de secundaria. Las respuestas dadas se sometieron a análisis utilizando con soporte informático el programa Aquad (versión 3.0). Palabras clave: Concepción, creencias, teoría personal, idea, evaluación, profesores de secundaria.ABSTRACT The present work tries to make a conceptualisation of the term conception. Traditionally, researchers have considered conceptions as a construct that includes the personal knowledge that tuman beings possess. It is not an exclusive term; in the educative field the term conception coexists with other designations as representation, beliefs, ideas, personal theories, attitudes, perspectives... People's conceptions arise from the interaction of three elements: the bioantrhopological nature, that is, the evolutionary process followed as species and its influence in knowledge; historical aspects that allow to preserve and transmit our past experiences; the whole of elements derived from our psychological particularity. In the second part of the work, we carried out an empirical study to detect which are the teachers conceptions in relation to the a series oftopics: what to evalúate, when to evalúate, how we should evalúate, how to improve evaluation, what it is to evalúate. In order to accomplish this, we made halfstructured interviews on secondary teachers. The given answers underwent an analysis using the software Aguad (3.0 versión). Key words: Conceptions, beliefs, ideas, evaluation, secondary teachers, Aquad.

Kinematic characteristics of the long jump approach run in paralympic-level male limb-deficients

The purpose of this study was to define the variables typifying the long jump approach run phase in paralympic-level male amputees. The sample comprised of the eleven (4 transtibial, 5 transfemoral and 2 single below-the-knee amputees). The parameters analysed were: official distance, toe-to-board distance, effective distance, stride contact time, stride flight time, total stride time, stride length, stride frequency, stride velocity, horizontal velocity, vertical velocity, resultant velocity, height of body center of mass, take-off stride angle, relative differences in stride length and relative differences in stride frequency. The findings of the study revealed that 77.8% of the para-athletes perform the take-off with the leg supported by the prosthesis. Horizontal velocity during the last three strides before take-off has been shown to have a high correlation with the official jump distance: 3rd last (r=0.65, p<0.05), 2nd last (r=0.69, p<0.05) and last (r=0.67, p<0.05) strides. Stride length and stride frequency patterns for the 3rd, 2nd and last strides were as follows: medium-long-short and high-low-high. Horizontal velocity at the last stride is higher compared to the preceding two. The findings of the study support the notion that a wide range of similarities exist in the running patterns and factors correlating with jumping distance between Paralympic amputee athletes and able-bodied high-level athletes

Solar and Interplanetary Magnetic Helicity Balance of Active Regions

Highlights of Astronomy. 2005. vol. 1

Potential use of space-based lightning detection in electric power systems

Information about lightning activity and its parameters is necessary to design and evaluate the lightning protection of an electrical power system. This information can be obtained from ground-based lightning detection networks that provide information on cloud-to-ground lightning strikes with a location accuracy of few hundred meters. Recently, the first satellite-based lightning optical detectors are operating continuously from geostationary orbits. These imagers observe the luminosity escaping from clouds to detect and locate total lightning activity with a spatial accuracy of several kilometers. This allows delineating the initiation and propagation (sometimes over tens to hundreds of kilometers before striking the ground) not observable by the ground-based networks. In this paper, we explore the use of this new technology for lightning protection in power systems. We focus on tall objects such as wind turbines and overhead transmission lines. We show how the optical detections allow identifying lightning flashes that likely produce continuing currents. This provides additional information for the identification of dangerous events and also can be used to estimate the number of upward-flashes from tall objects triggered by a nearby flash. The analysis of a transmission line shows the concentration of faults in the areas of high total lightning flash density. We found regional variations of the optical energy of the flashes along the line.This work was supported by research grants ESP2017-86263-C4-2-R funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, by the “European Union”; and Grants PID2019- 109269RB-C42 and ENE2017-91636-EXP funded by MCIN/AEI/ 10.13039/501100011033. S. Goodman was in part supported by NASA Grant 80NSSC18K1689. M. M. F. Saba was in part supported by research grants 2012/15375–7 and 2013/05784–0, from Sao ˜ Paulo Research Foundation (FAPESP). S. Visacro was supported by a research grant (307381/2019–6) of the Brazilian National Council of Technological and Scientific Development (CNPq). The GLM data are available from the NOAA National Centers for Environmental Information (NCEI) and Cloud Service Providers (e.g., Amazon Web Services, AWS). The LIS data are available from the NASA GHRC Distributed Active Archive Center (DAAC) (https:// https://ghrc.nsstc.nasa.gov/home/access-data. The power system information for the 500 kV transmission line is provided by ISA-INTERCOLOMBIA and is supported by L. Porras.Peer ReviewedPostprint (author's final draft

Local hydrological conditions influence tree diversity and composition across the Amazon basin

Tree diversity and composition in Amazonia are known to be strongly determined by the water supplied by precipitation. Nevertheless, within the same climatic regime, water availability is modulated by local topography and soil characteristics (hereafter referred to as local hydrological conditions), varying from saturated and poorly drained to well-drained and potentially dry areas. While these conditions may be expected to influence species distribution, the impacts of local hydrological conditions on tree diversity and composition remain poorly understood at the whole Amazon basin scale. Using a dataset of 443 1-ha non-flooded forest plots distributed across the basin, we investigate how local hydrological conditions influence 1) tree alpha diversity, 2) the community-weighted wood density mean (CWM-wd) – a proxy for hydraulic resistance and 3) tree species composition. We find that the effect of local hydrological conditions on tree diversity depends on climate, being more evident in wetter forests, where diversity increases towards locations with well-drained soils. CWM-wd increased towards better drained soils in Southern and Western Amazonia. Tree species composition changed along local soil hydrological gradients in Central-Eastern, Western and Southern Amazonia, and those changes were correlated with changes in the mean wood density of plots. Our results suggest that local hydrological gradients filter species, influencing the diversity and composition of Amazonian forests. Overall, this study shows that the effect of local hydrological conditions is pervasive, extending over wide Amazonian regions, and reinforces the importance of accounting for local topography and hydrology to better understand the likely response and resilience of forests to increased frequency of extreme climate events and rising temperatures

Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century