146 research outputs found
Forest fire severity estimation based on the LiDAR-PNOA data and the values of the Composite Burn Index
Revista oficial de la Asociación Española de Teledetección[EN] Mediterranean pine forests in Spain experience wildland fire events with different frequencies, intensities, and severities. An estimation of the fire severity as accurate as possible is required by forest managers to decide which strategy is most appropriate to mitigate the effect of fire. The aim of this research is to estimate the post-fire severity, relating a pool of independent variables derived from the LiDAR (Light Detection And Ranging) points clouds delivered by the National Plan for Aerial Orthophotography (PNOA) to field data based on Composite Burn Index collected in four fires located in Aragón (Spain). Logistic regression models were developed and statistically tested and validated to map fire severity with up to 85.5% accuracy. The canopy relief ratio and the percentage of all returns above one meter height were the most significant variables. In addition, the obtained results are compared to different spectral indices derived from Landsat Thematic Mapper.[ES] Los pinares mediterráneos españoles se ven afectados por incendios forestales con diferente frecuencia, intensidad y severidad. Para su valoración, hay que recurrir a estimaciones lo más precisas posibles de la severidad, la cual podrá ayudar a los gestores del bosque a decidir qué estrategia es más adecuada para mitigar el efecto del fuego. El objetivo de esta investigación es la estimación de la severidad post-incendio, relacionando un conjunto de variables independientes derivadas de las nubes de puntos del vuelo LiDAR (Light Detection And Ranging) del Plan Nacional de Ortofotografía Aérea (PNOA), con datos de campo basados en el índice CBI (Composite Burn Index) y recogidos en cuatro incendios localizados en Aragón. Se ha ajustado un modelo de regresión logística, que tras la validación, ha reportado una precisión del 85,5%, siendo las variables “canopy relief ratio” y el porcentaje de puntos por encima de 1 m de altura sobre el terreno, las incluidas en dicho modelo. Por otro lado, se ha realizado una comparativa de los resultados con índices espectrales derivados de imágenes Landsat Thematic Mapper.Estos trabajos han sido financiados por la beca pre-doctoral (FPI BOA 30, 11/02/2011) del Gobierno de Aragón y el proyecto CGL2014-57013-C2-2-R, y han contado con la ayuda de Francisco Palú, Marco Lorenzo y Emilio Pérez-Aguilar del Servicio Provincial de Agricultura, Ganadería y Medio Ambiente del Gobierno de Aragón. Los au-tores agradecen al Centro Nacional de Información Geográfica y al Centro de Información Territorial de Aragón por proporcionar los datos LiDAR-PNOA y al CENAD “San Gregorio” por facilitar el acceso a las parcelas de campo.Montealegre, AL.; Lamelas, MT.; Tanase, MA.; De La Riva, J. (2017). Estimación de la severidad en incendios forestales a partir de datos LiDAR-PNOA y valores de Composite Burn Index. Revista de Teledetección. (49):1-16. https://doi.org/10.4995/raet.2017.7371SWORD1164
Radiación solar en la provincia de Tucumán: una comparación entre valores estimados por satélite y medidos por una red solarimétrica
El modelo GL/CPTEC de estimación de radiación solar utiliza imágenes del satélite GOES (canal VIS) para América del Sur, procesándolas en régimen operacional. Los valores estimados para el área del Noroeste Argentino fueron comparados con medidas realizadas en 17 estaciones de la red de estaciones automáticas de la Estación Experimental Agroindustrial Obispo Colombres (EEAOC). Los valores diarios de GL en el trimestre octubre-diciembre de 2010 presentan elevada linealidad (R2>0,93) al comparar con mediciones de la red. En general, promedios trimestrales difieren en menos de 4% en la llanura tucumana y en la región montañosa, y en 4-7% en la región del pedemonte, cercana a la cadena del Aconquija. La desviación estándar de valores diarios en torno del desvío sistemático es de 20-35 W.m-2. Los campos de radiación mensual permiten discernir variaciones espaciales significativas en escala de algunas decenas de kilómetros. Son analizadas algunas fuentes de error y métodos de perfeccionamiento.Model GL/CPTEC assesses solar irradiance using GOES-VIS imagery for South America, being run in a operational scheme. Resultant GL values for Argentine Northwest region were compared with measurements at 17 automatic stations operated by Estación Experimental Agroindustrial Obispo Colombres. Daily GL values during three-month period October-December 2010 exhibit high linearity (R2>0.93) when compared with EEAOC network. Three-month mean values differ fom EEAOC means by less than 4% over eastern Tucumán and by 4-7% nearby mountainous Aconquija slope. Standard deviation of daily values around mean deviation is about 20-35 W.m-2. Monthly mean fields allow discern for space variability meaningful in a several ten-kilometers scale. Some error sources and quality improvements are analyzed.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES
Gains and losses in ecosystem services and disservices after converting native forest to agricultural land on an oceanic island
Habitat conversion to agricultural land is one of the main threats to terrestrial biodiversity and can affect ecosystem processes and cause changes in ecosystem services (ESs) and disservices (EDs). Yet, studies often rely only on the abundance and diversity of the service providers; the effects on ecological processes of habitat conversion are rarely directly monitored. In this study, we used the sentinel approach to evaluate how habitat conversion from native forest to agricultural land affected ESs and EDs on an oceanic island. We quantified herbivory on lettuce plants, invertebrate and vertebrate predation rates on artificial caterpillars, pollination on strawberry plants, seed predation on wheat and mustard seeds, and leaf decomposition rates in native forests, maize fields and pastures on Terceira Island, Azores (Portugal). Herbivory, invertebrate predation rates, and pollination service were not significantly different between habitats. Vertebrate predation rates in native forests (mean 6.1% d⁻¹) were significantly higher than that in pastures (0.3% d⁻¹), or high-elevation maize fields (0.5% d⁻¹), and marginally higher than in low-elevation maize fields (2.2% d⁻¹). Overall seed predation after 48 h was significantly higher on wheat (mean 16.8%) than mustard seeds (5.6%). High-elevation maize fields also had higher seed predation (27.8%) than low-elevation ones (0.6%) or pastures (3.6%), but did not differ from the native forest (12.9%). Decomposition after 90 days was highest in pastures (78.4% and 45.9%, for tea and rooibos, respectively); although no significant differences between habitats were detected, except for low-elevation maize fields (64.4% and 33.6%). Conversion from native forest to cultivated land did not cause a clear decrease in the intensity of the studied ESs/EDs except for vertebrate predation. Using direct monitoring tools to simultaneously and consistently quantify multiple ecological processes is not only possible but needed, as ecological processes can respond differently to landscape changes.This work was financed by FEDER (European Regional Development Fund) in 85% and by Azorean public funds by 15% through Operational Program Azores 2020, under the project AGRO-ECOSERVICES (ACORES01-0145-FEDER-000073).info:eu-repo/semantics/publishedVersio
The Impact of Donor Risk Index, Recipients’ and Operative Characteristics on Post Liver Transplant One-Year Graft Failure: A Cohort Analysis
Background and Aims: The donor risk index (DRI) quantifies donor-related characteristics potentially associated with increased risk of early graft failure. We aimed to assess the impact of the DRI, recipient and perioperative factors on post liver transplant (LT) outcomes. Methods: This was a singlecenter retrospective cohort study including all adult (≥18 years) patients who underwent LT from 01/2019 to 12/2019 at Curry Cabral Hospital, Lisbon, Portugal. Primary endpoint was 1-year graft failure post LT. Associations were studied with logistic regression. Results: A total of 131 cadaveric donor LT procedures were performed in 116 recipients. Recipients’ median (IQR) age was 57 (47–64) years and 101/131 (77.1%) were males. Cirrhosis was the underlying etiology in 95/131 (81.2%) transplants. Based on 8 predefined donors’ characteristics, median (IQR) DRI was 1.96 (1.67–2.16). Following adjustment for MELDNa score pre LT and SOFA score (adjusted odds ratio [aOR], 95% confidence interval [CI] = 0.91 [0.56–1.47]) or lactate (aOR [95% CI] = 2.76 [0.71–10.7]) upon intensive care unit (ICU) admission post LT, DRI was not associated with 1-year graft failure. However, higher SOFA
score (aOR [95% CI] = 1.20 [1.05–1.37]) or lactate (aOR [95% CI] = 1.27 [1.10–1.46]) upon ICU admission post LT were independently associated with higher odds of 1-year graft failure. Conclusions: In a recent cohort of patients who underwent LT, DRI, despite being high, was not associated with 1-year graft failure, but SOFA score or lactate upon ICU admission post LT were.info:eu-repo/semantics/publishedVersio
From Linear to Nonlinear Response in Spin Glasses: Importance of Mean-Field-Theory Predictions
Deviations from spin-glass linear response in a single crystal Cu:Mn 1.5 at %
are studied for a wide range of changes in magnetic field, . Three
quantities, the difference , the effective waiting time,
, and the difference are examined in our
analysis. Three regimes of spin-glass behavior are observed as
increases. Lines in the plane, corresponding to ``weak'' and
``strong'' violations of linear response under a change in magnetic field, are
shown to have the same functional form as the de Almeida-Thouless critical
line. Our results demonstrate the existence of a fundamental link between
static and dynamic properties of spin glasses, predicted by the mean-field
theory of aging phenomena.Comment: 9 pages, 10 figure
Survival after Resection of Multiple Tumor Foci of Intrahepatic Cholangiocarcinoma
Background: Multiple tumor foci of intrahepatic cholangiocarcinoma (ICC) are often considered a contra-indication for resection. We sought to define long-term outcomes after resection of ICC in patients with multiple foci.
Methods: Patients who underwent resection for ICC between 1990 and 2017 were identified from 12 major HPB centers. Outcomes of patients with solitary lesions, multiple lesions (ML), and oligometastases (OM) were compared. OM were defined as extrahepatic metastases spread to a single organ.
Results: One thousand thirteen patients underwent resection of ICC. On final pathology, 185 patients (18.4%) had ML and 27 (2.7%) had OM. Median survival of patients with a solitary tumor was 43.2 months, while the median survival of patients with 2 tumors was 21.2 months; the median survival of patients with 3 or more tumors was 15.3 months (p < 0.001). Five-year survival was 43.3%, 28.0%, and 8.6%, respectively. The median survival of patients without OM was 37.8 months versus 14.9 months among patients with OM (p < 0.001); estimated 5-year survival was 39.3% and 10.6%, respectively. In multivariable analysis, the presence of two lesions was not an independent poor prognostic factor for OS (HR 1.19; 95%CI 0.90-1.57; p = 0.229). However, the presence of three or more tumors was an independent poor prognostic factor for OS (HR 1.97; 95%CI 1.48-2.64; p < 0.001).
Conclusion: Resection of multiple liver tumors for patients with ICC did not preclude 5-year survival: in particular, estimated 5-year OS for resection of two tumors was 28.0%.info:eu-repo/semantics/publishedVersio
Polymorphisms in the BER and NER pathways and their influence on survival and toxicity in never-smokers with lung cancer
Polymorphisms in DNA repair pathways may play a relevant role in lung cancer survival in never-smokers. Furthermore, they could be implicated in the response to chemotherapy and toxicity of platinum agents. The aim of this study was to evaluate the influence of various genetic polymorphisms in the BER and NER DNA repair pathways on survival and toxicity in never-smoker LC patients. The study included never-smokers LC cases diagnosed from 2011 through 2019, belonging to the Lung Cancer Research In Never Smokers study. A total of 356 never-smokers cases participated (79% women; 83% adenocarcinoma and 65% stage IV). Survival at 3 and 5 years from diagnosis was not associated with genetic polymorphisms, except in the subgroup of patients who received radiotherapy or chemo-radiotherapy, and presented with ERCC1 rs3212986 polymorphism. There was greater toxicity in those presenting OGG1 rs1052133 (CG) and ERCC1 rs11615 polymorphisms among patients treated with radiotherapy or chemo-radiotherapy, respectively. In general, polymorphisms in the BER and NER pathways do not seem to play a relevant role in survival and response to treatment among never-smoker LC patients
Predicting Function Delay with a Machine Learning Model: Improve the Long-term Survival of Pancreatic Grafts
The impact of delayed graft function on outcomes following various solid organ transplants is well documented
and addressed in the literature. Delayed graft function following various solid organ transplants is associated with both short- and long-term graft survival issues. In a retrospective cohort study including 106 patients we evaluated whether pancreas graft survival differs according to moment of insulin therapy following simultaneous pancreaskidney transplant. As a result, we aimed to identify possible risk factors and build a machine-learning-based model that predicts the likelihood of dysfunction following SPK transplant patients based on day zero data after transplant, allowing to enhance pancreatic graft survival. Feature selection by Relief algorithm yielded donor features, age, cause of death, hemoglobin, gender, ventilation days, days in ICU, length of cardiac respiratory arrest and recipient features, gender, long-term insulin, dialysis type, time of diabetes mellitus, vPRA pre-Tx, number of HLA-A mismatches and PRDI, all contributed to the models' strength.info:eu-repo/semantics/publishedVersio
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