Planeación ambiental para la conservación de la biodiversidad en las Áreas operativas de Ecopetrol: Corregimiento en Encano Municipio de Pasto, Nariño

Los páramos azonales del Río Guamués tienen la particularidad de estar por debajo de los 3000 m.s.n.m., ubicándose en los fondos planos de los valles de los ríos El Estero y Guamués. Los Páramos Azonales ubicados al oriente del departamento de Nariño tienen una extensión de 3.120Ha (Delgado et al. 2007), su altura promedio es de 2800 m y están influenciados por las masas de Aire húmedo provenientes de la amazonia (Sarmiento, C., et al., 2013, Solarte et al., 2007). Estos Páramos Azonales se encuentra dentro del complejo de páramos La Cocha-Patascoy en Nariño(Martínez-Revelo y Lopera-Toro 2014, Morales Rivas et al. 2007), con un área de 3120 hectáreas Distribuidas en tres veredas Santa Teresita, Santa Lucía y Santa Isabel del corregimiento El Encano (Corponariño et al., 2002).San Juan de Pasto Nariñ

Listado de las arañas de Colombia (Arachnida: Araneae)

The present list reviews 914 species of spiders that occur in Colombia. The information was obtained and compiled from two hundred seventy-three scientific documents which provided the valid name of the species, distribution in the Americas and Colombia, elevation range of specimens, and the collections where specimens were deposited. The aim of this list is to be a quick reference tool for those interested in the existing arachnofauna of Colombia.Este listado contiene 914 especies de arañas citadas en localidades colombianas. Información recogida y compilada de 273 documentos científicos, que aportan el nombre válido de la especie, su distribución en América y en Colombia, así como el intervalo altitudinal en el cual han sido colectados, el museo en el que se encuentran depositados. Este listado pretende ser una herramienta de consulta rápida y eficaz para aquellos interesados en la aracnofauna existente en Colombia

Listado de las arañas de Colombia (Arachnida: Araneae)

The present list reviews 914 species of spiders that occur in Colombia. The information was obtained and compiled from two hundred seventy-three scientific documents which provided the valid name of the species, distribution in the Americas and Colombia, elevation range of specimens, and the collections where specimens were deposited. The aim of this list is to be a quick reference tool for those interested in the existing arachnofauna of Colombia

Informe final de actividades de campo la ventana de biodiversidad Río Guamués, Corregimiento El Encano, municipio de Pasto, Nariño, Colombia

El proyecto se orientó a formular participativamente un conjunto de lineamientos en materia de manejo y conservación de la matriz de páramos azonales y bosque altoandino en la Cuenca Alta del Río Guamués, a través de la investigación de indicadores biológicos agrupados en componentes taxonómicos de estudio en recorridos en campo.San Juan de Pasto, NariñoPlaneación ambiental para la conservación de la biodiversidad en las áreas operativas de Ecopetro

Spin diffusion versus proximity effect at ferromagnet/superconductor La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7-δ) interfaces

We report on the interplay between magnetism and superconductivity in La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7) structures. We have grown heterostructures (bilayers and trilayers) with a constant thickness of the ferromagnetic layer of 40 unit cells (15 nm) and changing the thickness of the superconductor between 1 (1.2 nm) and 40 unit cells (48 nm). The critical temperature of the bilayers decreases when the thickness of the superconductor is reduced below 10 unit cells, thus providing an estimate of the length scale of superconductivity suppression by spin-polarized quasiparticles in YBa_(2)Cu_(3)O_(7-δ) (YBCO) of 10 nm, much larger than the coherence length. For thickness of the YBCO layer smaller than 4 unit cells; a second mechanism of superconductivity depression comes into play, probably related to the ferromagnetic/superconducting proximity effect. The relative importance in depressing the critical temperature of intrinsic mechanisms (quasiparticle diffusion and proximity effect) and extrinsic ones (intralayer disorder, interface roughness, or reduced dimensionality of ultrathin layers) is discussed

Signatures of a two-dimensional ferromagnetic electron gas at the La_(0.7)Sr_(0.3)MnO_(3)/SrTiO_(3) interface arising from orbital reconstruction

The magnetoresistance of La0.7Sr0.3MnO3/SrTiO3La0.7Sr0.3MnO3/SrTiO3 superlattices with magnetic field rotating out-of-plane shows unexpected peaks for in-plane fields. Resistivity calculations with spin–orbit coupling reveal that orbital reconstruction at the manganite interface leads to a 2D ferromagnetic electron gas coupled antiparallel to the manganite “bulk”. These orbital and magnetic reconstructions are supported by X-ray linear dichroism and ab initio calculations

Origin of the inverse spin-switch behavior in manganite/cuprate/manganite trilayers

We studied ferromagnet/superconductor/ferromagnet trilayers based on La_(0.7)Ca_(0.3)MnO_(3) manganite and YBa_(2)Cu_(3)O_(7−δ) (YBCO) high-T_(c) cuprate with magnetoresistance and magnetization measurements. We find an inverse superconducting spin-switch behavior, where superconductivity is favored for parallel alignment of the magnetization in the ferromagnetic layers. We argue that this inverse superconducting spin switch originates from the transmission of spin-polarized carriers into the superconductor. In this picture, the thickness dependence of the magnetoresistance yields the spin-diffusion length in YBCO as 13 nm. A comparison of bilayers and trilayers allows ruling out the effect of the stray fields of the domain structure of the ferromagnet as the source of the inverse superconducting spin switch

Validation of three predictive models for suboptimal cytoreductive surgery in advanced ovarian cancer

The standard treatment for advanced ovarian cancer (AOC) is cytoreduction surgery and adjuvant chemotherapy. Tumor volume after surgery is a major prognostic factor for these patients. The ability to perform complete cytoreduction depends on the extent of disease and the skills of the surgical team. Several predictive models have been proposed to evaluate the possibility of performing complete cytoreductive surgery (CCS). External validation of the prognostic value of three predictive models (Fagotti index and the R3 and R4 models) for predicting suboptimal cytoreductive surgery (SCS) in AOC was performed in this study. The scores of the 3 models were evaluated in one hundred and three consecutive patients diagnosed with AOC treated in a tertiary hospital were evaluated. Clinicopathological features were collected prospectively and analyzed retrospectively. The performance of the three models was evaluated, and calibration and discrimination were analyzed. The calibration of the Fagotti, R3 and R4 models showed odds ratios of obtaining SCSs of 1.5, 2.4 and 2.4, respectively, indicating good calibration. The discrimination of the Fagotti, R3 and R4 models showed an area under the ROC curve of 83%, 70% and 81%, respectively. The negative predictive values of the three models were higher than the positive predictive values for SCS. The three models were able to predict suboptimal cytoreductive surgery for advanced ovarian cancer, but they were more reliable for predicting CCS. The R4 model discriminated better because it includes the laparotomic evaluation of the peritoneal carcinomatosis index

Controlled sign reversal of electroresistance in oxide tunnel junctions by electrochemical-ferroelectric coupling

The persistence of ferroelectricity in ultrathin layers relies critically on screening or compensation of polarization charges which otherwise destabilize the ferroelectric state. At surfaces, charged defects play a crucial role in the screening mechanism triggering novel mixed electrochemical-ferroelectric states. At interfaces, however, the coupling between ferroelectric and electrochemical states has remained unexplored. Here, we make use of the dynamic formation of the oxygen vacancy profile in the nanometerthick barrier of a ferroelectric tunnel junction to demonstrate the interplay between electrochemical and ferroelectric degrees of freedom at an oxide interface. We fabricate ferroelectric tunnel junctions with a La_0.7Sr_0.3MnO_3 bottom electrode and BaTiO_3 ferroelectric barrier. We use poling strategies to promote the generation and transport of oxygen vacancies at the metallic top electrode. Generated oxygen vacancies control the stability of the ferroelectric polarization and modify its coercive fields. The ferroelectric polarization, in turn, controls the ionization of oxygen vacancies well above the limits of thermodynamic equilibrium, triggering the build up of a Schottky barrier at the interface which can be turned on and off with ferroelectric switching. This interplay between electronic and electrochemical degrees of freedom yields very large values of the electroresistance (more than 10^6% at low temperatures) and enables a controlled switching between clockwise and counterclockwise switching modes in the same junction (and consequently, a change of the sign of the electroresistance). The strong coupling found between electrochemical and electronic degrees of freedom sheds light on the growing debate between resistive and ferroelectric switching in ferroelectric tunnel junctions, and moreover, can be the source of novel concepts in memory devices and neuromorphie computing

Expedición Colombia BIO. Biodiversidad y conservación de los sistemas subterráneos y ambientes exocársticos asociados en El Peñón, Santander, Colombia

La primera Expedición de Biodiversidad Colombia BIO - Instituto Humboldt se llevó a cabo en el municipio del Peñón en Santander, con el objetivo de abordar la diversidad de fauna y flora en los ecosistemas subterráneos (endocársticos) y los ambientes superficiales (exocársticos) asociados a las cuevas.BogotáSubdirección de Investigacione