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After peripheral nerve injuries, successful axonal growth and functional recovery requires the reprogramming of Schwann cells into a reparative phenotype, a process dependent on the activation of the transcription factor c-Jun. Nevertheless, axonal regeneration is greatly impaired in aged organisms or after chronic denervation leading to important clinical problems. This regenerative failure has been associated to a diminished c-Jun expression by Schwann cells, but whether the inability of these cells to maintain a repair state is associated to the transition into a phenotype inhibitory for axonal growth, has not been evaluated so far. We find that repair Schwann cells transitions into a senescent phenotype, characterized by diminished c-Jun expression and secretion of factor inhibitory for axonal regeneration in both aging and chronic denervation. In both conditions, elimination of senescent Schwann cells by systemic senolytic drug treatment or genetic targeting improves nerve regeneration and functional recovery in aging and chronic denervation, associated with an upregulation of c-Jun expression and a decrease in nerve inflammation. This work provides the first characterization of senescent Schwann cells and their impact over axonal regeneration in aging and chronic denervation, opening new avenues for enhancing regeneration, and functional recovery after peripheral nerve injuries.

Este trabajo analizó la relación entre la posición de flexión mantenida durante la práctica de ciclismo y la posible relación con dolor lumbar. Se llevó a cabo una revisión sistematizada a través del proceso PRISMA® entre 2015-2020, en las bases de datos PubMed, PEDro, Scopus y Web of Science, empleando los términos; “cycling”, “cyclist”, “position”, “positioning”, “overuse injury”, “spinal biomechanic”, “lower back”, “lower back pain”. Se seleccionaron 5 artículos que cumplieron con todos los criterios de inclusión. Los artículos seleccionados mostraron cambios en la inclinación pélvica, ángulos de flexión de tronco en tomadas medias y bajas del manillar de bicicleta de ruta y bicicleta de montaña, variaciones del asiento más arriba o atrás de la posición adecuada según longitud entrepiernas, la posición de rodilla 40º y tronco 35º de manera simultánea cuando el pedal está en 180º, mientras que en posición anatómica se describieron; ángulo máximo de inclinación de pelvis en anteversión, ángulo máximo de inclinación de pelvis en retroversión y ángulo máximo de flexión lumbar se asocian con molestias o dolor lumbar. Sin embargo, es posible establecer que la asociación entre la práctica de ciclismo y el dolor lumbar no ha sido suficientemente estudiada, lo que nos hace inferir que surge la necesidad de actualizar la información con el objetivo de prevenir este tipo de lesiones asociadas a la posición en ciclismo. Abstract. This article analyzed the relationship between the flexion position maintained during cycling and the possible relationship with low back pain. A systematic review was carried out through the PRISMA process between 2015-2020, in the PubMed, PEDro, Scopus and Web of Science databases, using the terms; "cycling", "cyclist", "position", "positioning", "injury from overuse", "biomechanics of the spine", "lumbar region", "low back pain". Five articles were selected that met all the inclusion criteria. Selected articles showed changes in pelvic tilt, torso flexion angles in medium and low strokes of the handlebars of the road bike and mountain bike, variations of the highest seat or the appropriate backrest according to the groin length, knee position 40 and trunk 35º simultaneously when the pedal is at 180º, while in anatomical position they have been described; The maximum angle of pelvic tilt in anteversion, the maximum angle of pelvic tilt in retroversion and the maximum angle of lumbar flexion are associated with pain or discomfort in the lumbar region. However, it is possible to establish that the association between cycling and low back pain has not been sufficiently studied, which leads us to infer that there is a need to update the information in order to prevent this type of injury associated with the position in cycling.

Introduction: In amphibians, blood may act as a hematopoietic tissue. However, the knowledge concerning hematological features is scarce, there is not much information that allows an analysis about the possible explanations of this physiological feature. Objective: This study aimed to evaluate the relationship between immature red blood cells (RBCs) mitosis and the presence of blood parasites in amphibians. Methods: We sampled 116 amphibians (31 species) in six Colombian localities. Blood was taken by cardiac puncture or maxillary vein puncture. Smears were prepared, fixed, and Giemsa stained for microscopical analysis. The variables analyzed were the percentage of immature RBCs, mitotic cells in peripheral blood, and blood parasite infection. Data were analyzed using Wilcoxon’s rank test and exact Fisher statistical tests. Results: Sixty-two individuals showed mitosis in peripheral blood, and these mitotic RBCs shared morphological features with immature RBCs. Overall, parasite prevalence was 30.1 %, distributed as follows: Trypanosoma (24.1 %), Hepatozoon-like (6 %), Dactylosoma (4.3 %), Karyolysus-like (0.9 %), and Filarioidea (2.6 %). A positive association between the percentage of immature RBCs and the presence of mitotic RBCs was found, and also between the blood parasite infection and the percentage of immature RBCs. Conclusions: In this study, we found that the presence of blood parasites, immature RBCs, and RBCs mitosis are frequent events in amphibians’ peripheral blood, and our analysis suggests an association between those features. Thus, the release of immature RBCs and the mitosis of those cells in peripheral blood may be a physiological response to blood parasite infection. Further studies characterizing hematology in amphibians and wildlife, in general, are desirable. Resumen Introducción: En anfibios, la sangre puede actuar como un tejido hematopoyético. Sin embargo, el conocimiento acerca de las características hematológicas es escaso y no hay información que permita un análisis acerca de las posibles explicaciones a este rasgo fisiológico. Objetivo: La intención de este estudio fue evaluar la relación entre la presencia de eritroblastos, mitosis de glóbulos rojos (GRs) y la infección por hemoparásito en sangre periférica de anfibios. Métodos: Se muestrearon 116 anfibios (31 especies) en seis localidades de Colombia. Se tomaron muestras de sangre mediante punción cardiaca o punción a la vena maxilar. Se prepararon extendidos sanguíneos, se fijaron y tiñeron con Giemsa para su posterior análisis por microscopía. Se analizaron variables como porcentaje de GRs inmaduros, células mitóticas en sangre periférica e infección por hemoparásitos. Los datos fueron analizados mediante el test de rango de Willcoxon y el test exacto de Fisher. Resultados: sesenta y dos individuos evidenciaron mitosis en sangre periférica y dichas mitosis compartían características morfológicas con GRs inmaduros. La prevalencia general de parásitos fue del 30.1 %, distribuido de la siguiente forma: Trypanosoma (24.1 %), Hepatozoon-like (6 %), Dactylosoma (4.3 %), Karyolysus-like (0.9 %), y Filarioidea (2. 6 %). Hay una asociación positiva entre el porcentaje de GRs inmaduros y la presencia de células mitóticas, también se encontró una relación entre la infección por hemoparásitos y el porcentaje de GRs inmaduros. Conclusiones: En este estudio encontramos que la presencia de parásitos sanguíneos, GRs inmaduros y mitosis de GRs son eventos frecuentes en sangre periférica de anfibios, y nuestros resultados sugieren una asociación entre dichas características. Por tanto, la liberación de GRs inmaduros y la mitosis de estas células en sangre periférica podría ser una respuesta fisiológica a infecciones parasitarias. Posteriores estudios que caractericen la hematología en anfibios y en vida silvestre en general, son deseables.

En el Ecuador el control vectorial y promoción de la salud está orientada a fortalecer la participación comunitaria y mantener un entorno saludable, libre de criaderos del mosquito Aedes aegypti y Aedes albopictus. La Universidad Estatal del Sur de Manabí en su rol con la sociedad, sustentado en el proyecto de vinculación “apoyo intersectorial para la prevención y control vectorial: dengue, chikungunya y zika en el cantón Jipijapa”, en interrelación con el distrito de salud 13D03, realiza acciones de vigilancia epidemiológica mediante visitas domiciliarias, destrucción de criaderos de mosquito, mingas barriales, limpieza de reservorios, abatización, educación intradomiciliaria. El objetivo es determinar la respuesta al apoyo intersectorial en vigilancia epidemiológica (dengue, chikungunya y zika) y actividades de atención primaria en salud, en el cantón jipijapa. La investigación fue no experimental, se utilizó el método descriptivo, de campo, aplicando un instrumento de recolección de información a 18.753 viviendas de las parroquias urbanas y rurales del cantón Jipijapa. Se inspeccionaron 16.646 viviendas en las parroquias urbanas de Jipijapa, de las cuales se constata que 4.487 viviendas poseen larvas en los reservorios; definiéndose el 27,3% en la parroquia urbana San Lorenzo, el 22,4% en la parroquia urbana Morán Lucio y el 19% en la parroquia urbana Parrales Y Guale. En las parroquias rurales se inspeccionaron 2.107 viviendas en las cuales 977 viviendas presentan larvas en los reservorios de agua, definiéndose el 65,7% en la parroquia rural El Anegado; el 31% en la parroquia rural La América y el 28,9% en la parroquia rural Julcuy.

Censorship normally refers to the Government's actions to ban different forms of freedom of speech (i.e. suppression of words or images). However, cries of censorship were heard as a result of the decision taken by television broadcast networks to interrupt the transmission of a Presidential press conference in November 2020. Some interpreted this act as censorship against public authorities. Others thought it was a legal (and necessary) measure to combat fake news. This article addresses whether the decision to limit a televised broadcast by President Trump was censorship or, alternatively, whether it was a valid, innovative measure to fight fake news. To tackle these issues, it is necessary that some of the related duties and rights television broadcast stations have before the Federal Communications Commission (FCC), governmental authority in charge of these matters, must be revised.

This work presents a novel method to auto-correct the trapping effect of laser-induced incandescence (LII) signals inside the flame to obtain soot volume fraction distributions in laminar axisymmetric (2D) and three-dimensional (3D) flames using planar LII. The development of the proposed model is described with an estimation of the propagated uncertainties. The proposed model is firstly numerically validated in a canonical 2D coflow Santoro flame using synthetic LII signals and soot properties predicted by the CoFlame code. Secondly, experimental measurements of LII were carried out in the same 2D coflow Santoro flame and the LII signals were converted to soot volume fraction using the proposed model. Simultaneous LII and line-of-sight attenuation measurements were conducted to obtain the calibration factor. The proposed model automatically took into account the signal trapping effect in the conversion of the detected LII signal to soot volume fraction. Finally, the validated methodology is applied to a 3D laminar boundary layer diffusion flame established in microgravity. The significant differences in the measured soot volume fraction distributions with and without considering signal trapping, particularly in the 3D zone of the flame, demonstrate the importance of considering signal trapping to LII measurements of soot volume fraction in this flame. The model developed in this work can be readily applied in planar LII measurements of soot in any flame configuration as long as it is steady or statistically steady, to allow measurements to be performed at different positions inside a flame, such as for pool-fires or pulsating flames.

Valparaiso, a central-southern region in Chile, has one of the highest rates of wildfire occurrence in the country. The constant threat of fires is mainly due to its highly flammable forest plantation, composed of 97.5% Pinus radiata and Eucalyptus globulus. Fuel moisture content is one of the most relevant parameters for studying fire spreading and risk, and can be estimated from the reflectance of leaves in the short wave infra-red (SWIR) range, not easily available in most vision-based sensors. Therefore, this work addresses the problem of estimating the water content of leaves from the two previously mentioned species, without any knowledge of their spectrum in the SWIR band. To this end, and for validation purposes, the reflectance of 90 leaves per species, at five dehydration stages, were taken between 350 nm and 2500 nm (full spectrum). Then, two machine-learning regressors were trained with 70% of the data set to determine the unknown reflectance, in the range 1000 nm–2500 nm. Results were validated with the remaining 30% of the data, achieving a root mean square error less than 9% in the spectrum estimation, and an error of 10% in spectral indices related to water content estimation.

Los contratos inteligentes pueden definirse como protocolos computacionales que aseguran la ejecución de prestaciones de manera automática, reduciendo los riesgos de incumplimiento de las partes, anulando la intermediación de terceros y garantizando la seguridad suficiente para impedir que los extremos de un contrato modifiquen arbitrariamente las cláusulas desfavorables o impidan la ejecución de las prestaciones incómodas. No obstante, a pesar del entusiasmo que han provocado los contratos inteligentes, estos también han incitado muchas inquietudes, en especial para la ciencia del derecho, pues si bien su aplicación promete revolucionar las relaciones de los sectores industriales modernos y las relaciones entre particulares, también han generado cuestionamientos sobre su validez, naturaleza jurídica, libertad negocial, disciplina normativa, coherencia con el derecho privado, interpretación y posibilidad de revisión judicial, entre otros temas que requieren respuesta por parte de la doctrina jurídica. Con el propósito de contribuir a la temática desde el punto de vista jurídico, el presente libro describe las características técnicas y funcionales de los contratos inteligentes, su naturaleza jurídica, función económica, sus principios y elementos constitutivos, así como el alcance y los límites que tiene la autonomía privada para su celebración y ejecución bajo el amparo del ordenamiento jurídico colombiano.

Wildfires have caused significant damage in Chile in the last decade, with electrical infrastructure being particularly vulnerable to extreme wildfire events. Therefore, the objective of this work is to estimate the risk of a wildfire damaging an electrical substation operated by the Chilean company Chilquinta Distribución SA, located in the Wildland-Urban Interface (WUI) of the city of Valparaiso, Chile. A Wildfire Quantitative Risk Analysis (WFQRA) framework is proposed for this purpose, where the quantification of risk results from the product between the probability of a wildfire reaching the WUI and its consequences. The former was determined with an event tree analysis, a tool in which the advance in time of the initiating event (ignition of a wildland fuel) was analyzed through a series of questions related to the area burned, wind direction and ranges of ambient temperature and wind speed, with answers of the type yes or no. This anaylsis gave 0.004 events/year as the probability of a wildfire reaching the WUI. On the other hand, the analysis of consequences requires determining the vulnerability of the object of study to a thermal insult, which is the quantitative relationship between the thermal exposure of the object to the fire and the damage experienced by it. This vulnerability was assessed by expressing it in terms of a probability of failure (ignition) for different doses of thermal radiation, i.e., a dose-response curve. Since these curves are typically of sigmoid shape, a novel probit equation was determined by analyzing experimental data of PMMA, a material that served as a proxy for the actual materials within the electrical substation. Thermal exposure of a target within the substation was calculated with an average fireline intensity (1832 kW/m) and flame length (3.98 m) obtained with FlamMap simulations of fire behavior in a simplified landscape representing the study area. With these results, the vulnerability model for PMMA developed in this work gave PMMA ignition probabilities of 0.029 and 0.269 for two wildfire scenarios considered in the substation. Finally, wildfire risk was estimated as 10-4 to 10-3 events/year, or equivalently, one event every 1,000 to 10,000 years. These results can be used as input to the decision-making process in Chilquinta and public institutions for taking mitigation measures to reduce wildfire risk in the WUI. Future work will be focused on refining this result.

Disturbances alter biodiversity via their specific characteristics, including severity and extent in the landscape, which act at different temporal and spatial scales. Biodiversity response to disturbance also depends on the community characteristics and habitat requirements of species. Untangling the mechanistic interplay of these factors has guided disturbance ecology for decades, generating mixed scientific evidence of biodiversity responses to disturbance. Understanding the impact of natural disturbances on biodiversity is increasingly important due to human-induced changes in natural disturbance regimes. In many areas, major natural forest disturbances, such as wildfires, windstorms, and insect outbreaks, are becoming more frequent, intense, severe, and widespread due to climate change and land-use change. Conversely, the suppression of natural disturbances threatens disturbance-dependent biota. Using a meta-analytic approach, we analysed a global data set (with most sampling concentrated in temperate and boreal secondary forests) of species assemblages of 26 taxonomic groups, including plants, animals, and fungi collected from forests affected by wildfires, windstorms, and insect outbreaks. The overall effect of natural disturbances on α-diversity did not differ significantly from zero, but some taxonomic groups responded positively to disturbance, while others tended to respond negatively. Disturbance was beneficial for taxonomic groups preferring conditions associated with open canopies (e.g. hymenopterans and hoverflies), whereas ground-dwelling groups and/or groups typically associated with shady conditions (e.g. epigeic lichens and mycorrhizal fungi) were more likely to be negatively impacted by disturbance. Across all taxonomic groups, the highest α-diversity in disturbed forest patches occurred under moderate disturbance severity, i.e. with approximately 55% of trees killed by disturbance. We further extended our meta-analysis by applying a unified diversity concept based on Hill numbers to estimate α-diversity changes in different taxonomic groups across a gradient of disturbance severity measured at the stand scale and incorporating other disturbance features. We found that disturbance severity negatively affected diversity for Hill number q = 0 but not for q = 1 and q = 2, indicating that diversity–disturbance relationships are shaped by species relative abundances. Our synthesis of α-diversity was extended by a synthesis of disturbance-induced change in species assemblages, and revealed that disturbance changes the β-diversity of multiple taxonomic groups, including some groups that were not affected at the α-diversity level (birds and woody plants). Finally, we used mixed rarefaction/extrapolation to estimate biodiversity change as a function of the proportion of forests that were disturbed, i.e. the disturbance extent measured at the landscape scale. The comparison of intact and naturally disturbed forests revealed that both types of forests provide habitat for unique species assemblages, whereas species diversity in the mixture of disturbed and undisturbed forests peaked at intermediate values of disturbance extent in the simulated landscape. Hence, the relationship between α-diversity and disturbance severity in disturbed forest stands was strikingly similar to the relationship between species richness and disturbance extent in a landscape consisting of both disturbed and undisturbed forest habitats. This result suggests that both moderate disturbance severity and moderate disturbance extent support the highest levels of biodiversity in contemporary forest landscapes., British Ecological Society LRB20/1002, Junta de Andalucia, European Commission B-FQM-366-UGR20, Centro ANID Basal FB210015, Direccion de Investigacion Universidad de La Frontera DIUFRO DI20-0066, Federal Ministry of Education & Research (BMBF), Max Planck Society, INCT Madeiras da Amazonia, Federal Ministry of Education & Research (BMBF) 01LB1001A 01LK1602A, Brazilian Ministry of Science, Technology and Innovation (MCTI/FINEP) 01.11.01248.00, Russian Science Foundation (RSF) 21-14-00227, Ministry of Education, Youth & Sports - Czech Republic Czech Republic Government LTC 20058, Czech Academy of Sciences RVO67985939, UK Research & Innovation (UKRI), Natural Environment Research Council (NERC) GR3/11743, Greek project POL-AEGIS, Program THALES MIS 376737, Projekt DEAL TH 2218/5-1

The Las Máquinas wildfire took place in central Chile in the austral summer season of 2017 has becomes the most severe event in Chilean history, causing loss of life, property and the destruction of native forest, crops, large areas of commercial plantations and biodiverse habitats. Since this event has no precedent in Chilean wildfire history, it was used as an example to carry out a detailed analysis of the conditions before (pre-), during (per-) and after (post-) the fire from a remote sensing perspective. The goal of this work is to develop a framework to carry out detailed analyses of catastrophic fires for forensic and public policy purposes, making use of the advantages posed by Earth Observation satellites, including the simultaneous imaging of large areas with a good spatial resolution, and an ever-increasing temporal resolution, coupled with a sophisticated suite of instruments which allow measuring many parameters simultaneously. This study examines the biophysical, meteorological and physical variables like the evolution of the Normalized Difference Vegetation Index (NDVI), weather conditions, maximum temperature evolution, the Canadian Fire Weather Index, the burned area, the maximum fire radiative power, among others, for the five municipalities that were affected by the fire: Cauquenes, Chanco, Empedrado, Constitución and San Javier, all of which are located in the Maule Region. The results indicate that Las Maquinas wildfire took place under exceptional meteorological conditions. In particular, the conditions before the night when Santa Olga was destroyed were characterized by record values of the FWI, which caused a significant increase in the burned area and overwhelmed any response by the fire brigades.

The effects of adding water-vapor to the oxidizer stream on soot production in laminar coflow diffusion flames under different oxygen indices (OI) were investigated both experimentally and numerically. A modified coflow Gulder-type burner was employed to produce the laminar ethylene flames for fifteen different conditions of the oxidizer stream from oxygen-deficient (OI 17%) to oxygen-enriched (OI 25%) conditions, and also without and with adding water-vapor into the oxidizer stream up to 10% on mole basis. The measured soot volume fractions were compared with numerical predictions obtained using the CoFlame code and a chemical kinetic mechanism that consists of reaction pathways up to 5-ring PAHs. The sectional soot model used to simulate the soot particles dynamics considers soot nucleation, surface growth, PAH condensation, oxidation, particle coagulation and fragmentation. Fairly good agreement between experimental and numerical results was found, as close as 1% and 5% of difference in the peak soot volume fraction for OI21% with 0% and 10% of water-vapor addition, respectively. Clear trends of increasing the soot volume fraction (peak and also overall) was observed with increasing OI, while a significant reduction was obtained with the addition of the water-vapor. For the cases analyzed, a reduction of the total soot content was up to 60%. The chemical effects were numerically isolated using non-reacting water-vapor and analyzed, contributing especially to the soot oxidation rates. Finally, a study of the main reaction pathways was performed to better understand the chemical effects of water vapor. The results show that water vapor addition affects the concentrations of H and OH radicals and alters the formation and oxidation of soot precursors.

This work presents a layer-peeling (LP) algorithm to correct the signal trapping effect in planar laser-induced incandescence (LII) measurements of soot volume fraction. The method is based on measurements of LII signals captured by an intensified CCD camera at a series of parallel planes across a diffusion flame. A method based on presumed function (PF) of soot volume fraction is also proposed for comparison. The presented methods are numerically tested based on synthetic LII signals emitted from a simulated axisymmetric laminar diffusion flame using the CoFlame code. Numerical results showed that the LP method is able to correct the signal trapping effect, even for fairly large optical thicknesses and in a wide range of detection wavelengths. The correction decreases the relative errors induced by neglecting the trapping effect considerably. The signal trapping effect correction is less important for the determination of integrated soot quantities such as radially integrated soot volume fraction or total soot loading. Planar LII measurements were carried out and calibrated in order to test the method experimentally in a coflow flame. The LP, PF and a simplified analytical (SA) model were compared. The results indicate that the differences in soot volume fraction of 1 ppm or about 15% are obtained in zones of maximum soot loading of 6.5 ppm when the trapping effect is accounted for. Also, the LP and SA methods were found computationally efficient and accurate compared to the PF method. Although the study was performed in a canonical laminar axisymmetric flame, the proposed method can be applied to any statistically steady 3D flame.

International audience; The main characteristics of pool fire flames are flame height, air entrainment, pulsation of the flame, formation and properties of soot particles, mass burning rate, radiation feedback to the pool surface, and the amount of pollutants including soot released to the environment. In this type of buoyancy controlled flames, the soot content produced and their subsequent thermal radiation feedback to the pool surface are key to determine the self-sustainability of the flame, their mass burning rate and the heat release rate. The accurate characterization of these flames is an involved task, specially for modelers due to the difficulty of imposing adequate boundary conditions. For this reason, efforts are being made to design experimental campaigns with well-controlled conditions for their reliable repeatability, reproducibility and replicability. In this work, we characterized the production of soot in a surrogate pool fire. This is emulated by a bench-scale porous burner fueled with pure ethylene burning in still air. The flame stability was characterized with high temporal and spatial resolution by using a CMOS camera and a fast photodiode. The results show that the flame exhibit a time-varying propagation behavior with a periodic separation of the reactive zone. Soot volume fraction distributions were measured at nine locations along the flame centerline from 20 to 100 mm above the burner exit using the auto-compensating laser-induced incandescence (AC-LII) technique. The mean, standard deviation and probability density function of soot volume fraction were determined. Soot volume fraction presents an increasing tendency with the height above the burner, in spite of a local decrease at 90 mm which is approximately the position separating the lower and attached portion of the flame from the higher more intermittent one. The results of this work provide a valuable data set for validating soot production models in pool fire configurations.