Determinación de la humedad de suelo mediante regresión lineal múltiple con datos TerraSAR-X

Revista oficial de la Asociación Española de Teledetección[EN] The first five centimeters of soil form an interface where the main heat fluxes exchanges between the land surface and the atmosphere occur. Besides ground measurements, remote sensing has proven to be an excellent tool for the monitoring of spatial and temporal distributed data of the most relevant Earth surface parameters including soil’s parameters. Indeed, active microwave sensors (Synthetic Aperture Radar - SAR) offer the opportunity to monitor soil moisture (HS) at global, regional and local scales by monitoring involved processes. Several inversion algorithms, that derive geophysical information as HS from SAR data, were developed. Many of them use electromagnetic models for simulating the backscattering coefficient and are based on statistical techniques, such as neural networks, inversion methods and regression models. Recent studies have shown that simple multiple regression techniques yield satisfactory results. The involved geophysical variables in these methodologies are descriptive of the soil structure, microwave characteristics and land use. Therefore, in this paper we aim at developing a multiple linear regression model to estimate HS on flat agricultural regions using TerraSAR-X satellite data and data from a ground weather station. The results show that the backscatter, the precipitation and the relative humidity are the explanatory variables of HS. The results obtained presented a RMSE of 5.4 and a R2 of about 0.6[ES] Los primeros cinco centímetros del suelo forman una interfaz donde se producen los principales intercam-bios de flujos de calor entre la superficie terrestre y la atmósfera. La teledetección ha demostrado ser una excelente herramienta para el seguimiento de datos espacial y temporalmente distribuidos de las características sobresalientes de la superficie terrestre, incluidos los parámetros del suelo. Los sensores de microondas activos (Synthetic Aperture Radar- SAR) ofrecen la posibilidad de monitorizar la humedad de suelo (HS) a escala global, regional y local, mediante la modelación de los procesos involucrados. Diversos algoritmos de inversión han sido desarrollados para derivar información geofísica, como HS, a partir de información SAR. Muchos de ellos utilizan modelos electromagnéticos para simular el coeficiente de retrodispersión y se basan en técnicas estadísticas tales como redes neuronales, mé-todos de inversión y modelos de regresión. Estudios recientes han demostrado que las técnicas simples de regresión múltiple arrojan resultados aceptables. Las variables geofísicas implicadas en estas metodologías son descriptivas de la estructura del suelo, las características de las microondas y la cobertura del suelo. Por esto, en este trabajo se propone desarrollar un modelo de regresión lineal múltiple para estimar HS en zonas de llanura combinando datos de la misión satelital TerraSAR-X y datos de una estación meteorológica. La modelación propuesta involucra las variables hidrológicas que caracterizan las zonas de llanura, donde los movimientos verticales de agua en el suelo predominan sobre el escurrimiento horizontal. Los resultados obtenidos muestran que la retrodispersión, la precipitación y la hu-medad relativa del aire son las variables explicativas de HS. El modelo obtenido arrojó un RMSE de 5,4 y un R2 de 0,6.García, G.; Brogioni, M.; Venturini, V.; Rodriguez, L.; Fontanelli, G.; Walker, E.; Graciani, S.... (2016). Soil moisture estimation using multi linear regression with terraSAR-X data. Revista de Teledetección. (46):73-81. doi:10.4995/raet.2016.4024.SWORD73814

A fatal case of recurrent amiodarone-induced thyrotoxicosis after percutaneous tracheotomy: a case report

<p>Abstract</p> <p>Background</p> <p>Amiodarone is a widely used antiarrythmic drug, which may produce secondary effects on the thyroid. In 14–18% of amiodarone-treated patients, there is overt thyroid dysfunction, usually in the form of amiodarone-induced thyrotoxicosis, which can be difficult to manage with standard medical treatment.</p> <p>Case presentation</p> <p>Presented is the case of a 65-year-old man, under chronic treatment of atrial fibrillation with amiodarone, who was admitted to the Intensive Care Unit with acute cardio-respiratory failure and fever. He was recently hospitalized with respiratory distress, attributed to amiodarone-induced pulmonary fibrosis. Clinical and laboratory investigation revealed thyrotoxicosis due to amiodarone treatment. He was begun on thionamide, prednisone and beta-blockers. After a short term improvement of his clinical status the patient underwent percutaneous tracheotomy due to weaning failure from mechanical ventilation, which led to the development of recurrent thyrotoxicosis, unresponsive to medical treatment. Finally, the patient developed multiple organ failure and died, seven days later.</p> <p>Conclusion</p> <p>We suggest that percutaneous tracheotomy could precipitate a thyrotoxic crisis, particularly in non-euthyroid patients suffering from concurrent severe illness and should be performed only in parallel with emergency thyroid surgery, when indicated.</p

Ice Sheet and Sea Ice Ultrawideband Microwave radiometric Airborne eXperiment (ISSIUMAX) in Antarctica: first results from Terra Nova Bay

An airborne microwave wide-band radiometer (500–2000 MHz) was operated for the first time in Antarctica to better understand the emission properties of sea ice, outlet glaciers and the interior ice sheet from Terra Nova Bay to Dome C. The different glaciological regimes were revealed to exhibit unique spectral signatures in this portion of the microwave spectrum. Generally, the brightness temperatures over a vertically homogeneous ice sheet are warmest at the lowest frequencies, consistent with models that predict that those channels sensed the deeper, warmer parts of the ice sheet. Vertical heterogeneities in the ice property profiles can alter this basic interpretation of the signal. Spectra along the lengths of outlet glaciers were modulated by the deposition and erosion of snow, driven by strong katabatic winds. Similar to previous experiments in Greenland, the brightness temperatures across the frequency band were low in crevasse areas. Variations in brightness temperature were consistent with spatial changes in sea ice type identified in satellite imagery and in situ ground-penetrating radar data. The results contribute to a better understanding of the utility of microwave wide-band radiometry for cryospheric studies and also advance knowledge of the important physics underlying existing L-band radiometers operating in space.</p

Understanding the molecular determinants driving the immunological specificity of the protective pilus 2a backbone protein of Group B Streptococcus

The pilus 2a backbone protein (BP-2a) is one of the most structurally and functionally characterized components of a potential vaccine formulation against Group B Streptococcus. It is characterized by six main immunologically distinct allelic variants, each inducing variant-specific protection. To investigate the molecular determinants driving the variant immunogenic specificity of BP-2a, in terms of single residue contributions, we generated six monoclonal antibodies against a specific protein variant based on their capability to recognize the polymerized pili structure on the bacterial surface. Three mAbs were also able to induce complement-dependent opsonophagocytosis killing of live GBS and target the same linear epitope present in the structurally defined and immunodominant domain D3 of the protein. Molecular docking between the modelled scFv antibody sequences and the BP-2a crystal structure revealed the potential role at the binding interface of some non-conserved antigen residues. Mutagenesis analysis confirmed the necessity of a perfect balance between charges, size and polarity at the binding interface to obtain specific binding of mAbs to the protein antigen for a neutralizing response