Estimación de biomasa forestal mediante el uso de imágenes radar.

La importancia de la Biomasa a nivel mundial, ha llevado a que más de 130 países celebren el protocolo de Kioto sobre el cambio climático dictaminando como objetivo la reducción de las emisiones de seis gases de efecto invernadero y tres gases industriales fluorados, así como la incorporación de la fijación del CO2 como un objetivo dentro de los criterios de gestión de bosques. Entre las metodologías no destructivas para estimación de biomasa, aquí desarrolladas se describen tres técnicas que varios autores han propuesto para calcular los valores de biomasa y carbono, tal como el uso de ecuaciones alométricas por medio de la medición de variables dasométricas como el DAP, la aplicación de la teoría de huecos (v.g. DHP, TRAC), y la obtención de biomasa mediante información radar. Las imágenes radar proporcionan una clara ventaja al poder ser adquiridas en cualquier momento del día e independientemente de las condiciones climatológicas. Se han adquirido dos imágenes de sensores diferentes, tal como ALOSPALSAR que trabaja en la banda L y RADARSAT-2 que trabaja en la banda C, se aplica la metodología descrita por Saatchi et al. (2007), desarrollando los algoritmos semiempíricos propuestos para la estimación de biomasa del fuste (Ws) y biomasa de la copa (Wc), obteniendo los coeficientes a partir de información adquirida en campo. ABSTRACT The importance of biomass worldwide has led to more than 130 countries to celebrate the Kyoto Protocol, aimed at reducing emissions of six greenhouse gases and three fluorinated industrial gases, and the incorporation of the fixation of CO2 as an objective within forest management criteria. Among the non-destructive methods for estimating biomass, three techniques were developed. These have been described by some authors, as the use of allometric equations by measuring forest variables such as the DAP, the application of the Gap Theory (e.g. DHP, TRAC), as well as deriving biomass by radar information. The radar images provide a clear advantage since they can be gathered at any time of the day regardless of the weather conditions. For this purpose, two radar products have acquired from different sensors, such as ALOSPALSAR operating on L frequency band and RADARSAT-2 operating on C frequency band. The methodology applied in this work is described in Saatchi et al. (2007), that develop semiempirical algorithms for estimating stem biomass (Ws) and crown biomass (Wc). The corresponding coefficients are determined by means of regression procedures using field information derived from allometric and radiation measurements

Adoption of e-commerce by individuals and digital divide: Evidence from Spain

E-commerce penetration rates are distant among those groups of individuals with the lowest and the highest levels of online shopping adoption. This is an indicator of digital divide, having negative effects in terms of untapped opportunities for people, companies and the whole economy. Key socioeconomic and demographic determinants of adoption of ecommerce are explored, analyzing a dataset of 174,776 observations for the period 2008-2017 in Spain. The empirical analysis is based on a standard neoclassical utility maximization framework. Linear probability model, logistic regression, and Heckman’s sample selection correction model have been used. The results suggest that e-commerce adoption is positively related with being male, having higher levels of education, income and digital skills, being Spanish, and being employed; while being female, older and belonging to a household of two or more members have negative effects. An interaction between digital skills and age has been introduced in the model, where high digital skills seem to have a positive influence, partly counteracting the lower odds for some age groups. Policy recommendations related to demand and supply measures are suggested to foster the adoption of e-commerce

Digital divides across consumers of internet services in Spain using panel data 2007-2019. Narrowing or not?

Digital gaps have the potential to exacerbate the inequalities that exist in society. The main objective of this paper is to study the gaps that occur in the use of internet services by households in Spain during the period 2007-2019 and to become useful in the design of policies addressed to narrow specific digital divides. The data is a panel obtained from the ICT-H Survey on Households of the National Statistics Institute. This paper defines the gaps as the differences in the use of internet services across individual consumers. A selected group of twelve digital services are considered: e-commerce, e-selling, e-tourism, e-learning, e-health, e-banking, e-government, VoIP, chat, email, cloud services, and social networks. The second level digital gaps are analyzed in each service according to six relevant socio-demographic characteristics: gender, age, education, digital skills, population size, and income. A set of graphs show the evolution of the gaps. Gaps are narrowing in most dimensions and specific characteristics, but not in others such as age, education, and digital skills. The gaps reveal the evolution of digitization and in some cases of digital exclusion for specific groups. Specific knowledge about digital gaps is useful for policymakers, since closing the digital divide is an explicit policy goal in this country, as well as in other parts of Europe. Then, a dynamic panel data model was proposed and estimated using Arellano and Bond techniques. A dynamic/network effect was found, as well as other socio-demographic determinants. Finally, the paper contains conclusions, policy recommendations and an agenda for future research. The policy recommendations consist of digital education programs targeted at the most exposed groups such as the elderly, the less well-educated and people with lower digital skills

Contribución por grupos de edad a la mortalidad esperada por COVID-19 en Argentina y Colombia

Introducción.- Este estudio tuvo como objetivo explorar la serie de posibles heterogeneidades que subyacen a la aparente similitud en ciertos indicadores no refinados de mortalidad por COVID-19 -como las tasas brutas de mortalidad o las muertes por millón de habitantes- en Argentina y Colombia. Se realizó un estudio en el que se utilizaron datos agregados de los informes diarios de vigilancia epidemiológica proporcionados por los ministerios de salud de Argentina y de Colombia, para explorar diferenciales en el nivel poblacional mediante el uso de técnicas clásicas de estandarización demográfica. Resultados.- Se detectó que el impacto de la mortalidad y la letalidad de casos es mayor en Colombia, debido a que tiene una estructura poblacional y de casos positivos de menor edad que Argentina. En especial, la mayoría de las diferencias entre países puede explicarse por ciertos grupos de edad. Discusión.- El hallazgo principal ha sido que la gran mayoría de las defunciones esperadas en Argentina y Colombia ocurrió en los grupos de 50 y de 80 años, lo que implica que el riesgo real de muerte para la población colombiana puede ser mayor que el observado para dichos grupos etarios

Aplicación de modelos geoestadísticos para definir la variabilidad de un perfil del suelo

El análisis geoestadisticos es utilizado para visualizar y graficar la distribución espacial de varias propiedades del suelo. En este contexto, los objetivos fueron: Describir varias propiedades fisicoquímicas del suelo de dos perfiles en una finca bananera; para luego estimar el mejor método de interpolación, y mediante gráficas interpretar la variabilidad espacial. Se construyó dos calicatas de 2,50 m de ancho por 0,70 m de profundidad ubicadas diagonal a una planta de banano a distancia de 40 cm. En cada perfil se colocó una malla de 2 m de largo por 0.6 m de ancho con cuadrículas de 20× 20 cm, de donde se tomó muestras para análisis de suelo. El análisis geoestadístico se realizó en ArcGis versión 10.3. Para mostrar la distribución de los datos del perfil, se utilizó el método de interpolación kriging. Los modelos de semivariograma de tipo empíricos usados fueron: lineal, esférico, circular y gaussiano. Se identificó áreas con diferente variabilidad en su dirección concentración de datos en función de la distancia. El modelo de interpolación esférico fue más preciso. Los mapas mantuvieron la continuidad de los valores en profundidad, aspecto que permitió caracterizar los dos perfiles de suelo, al ser comprado con la estadística descriptiva. Palabras clave: Sistema de información geográfico, Krigrien, semivariograma, error cuadrático medio.   ABSTRACT Geostatistical analysis is used to visualize and graph the spatial distribution of various soil properties. In this context, the objectives were: to describe several physicochemical properties of the soil of two profiles in a banana farm; then to estimate the best interpolation method, and through graphs to interpret the spatial variability. Two 2.50 m wide by 0.70 m deep pits were constructed diagonally to a banana plant at a distance of 40 cm. A 2 m long by 0.6 m wide mesh with 20 x 20 cm squares was placed in each profile, from which samples were taken for soil analysis. The geostatistical analysis was performed in ArcGis version 10.3. To show the distribution of the profile data, the kriging interpolation method was used. The empirical semivariogram models used were: linear, spherical, circular and Gaussian. Areas with different variability in their direction and data concentration as a function of distance were identified. The spherical interpolation model was more accurate. The maps maintained continuity of the values in depth, an aspect that allowed the characterization of the two soil profiles, when bought with the descriptive statistics. Keywords: Geographic information system, Krigrien, semivariogram, mean square error

DISTRIBUIÇÃO ESPACIAL DE ATRIBUTOS DO SOLO NA REGIÃO DE EL ORO, EQUADOR

The mathematical modeling to semivariogram, moderated by geostatistics, is a tool capable of contributing to sustainable research. The need for soil studies in the province of El Oro, Ecuador, made it possible to carry out this study and generate information through analysis of variability and establishment of spatial dependence structure and linear correlation of some soil attributes, in order to assist in the planning of activities in six cities. In all of them, initial descriptive analysis, geostatistics and simple linear correlation matrix were performed based on a mesh with 368 sample points. Only pH and sand presented a high coefficient of variation (22.02% and 25.42%), all other attributes presented very high variation. Most semivariograms were fitted to the spherical model; the highest range was indicated by magnesium (41,500 m) and the lowest by copper (7,740 m). The number of pairs in the first LAG showed influence on the range and on the ADE for Zinc content. The Mg pair versus base sum was the highest linear correlation among all attributes analyzed. The pH was highlighted as an intermediary and influencer of other attributes of the soil.A modelagem matemática ao semivariograma, moderado pela geoestatística, é uma ferramenta capaz de contribuir para pesquisas sustentáveis. A necessidade de estudos de solo na provincia de El Oro, Equador, possibilitou relizar esse estudo e gerar informações por meio da análise de variabilidade e estabelecimento da estrutura de dependência espacial e correlação linear de alguns atributos do solo, a fim de auxiliar no planejamento de atividades agrícolas em seis cidades. Em todas elas foram realizadas análise descritiva inicial, geoestatística e matriz de correlação linear simples com base em uma malha com 368 pontos amostrais. Apenas o pH e areia apresentaram coeficiente de variação alta (22,02% e 25,42%), todos os outros atributos apresentaram variação muito alta. A maioria dos semivariogramas foram ajustados ao modelo esférico; o maior alcance foi indicado pelo magnésio (41.500 m) e o menor pelo cobre (7.740 m). O número de pares no primeiro LAG mostrou influência no alcance e no ADE para o teor de Zinco. O par Mg versus soma de bases foi a maior correlação linear dentre todos os atributos analisados. O pH se destacou como intermediador e influenciador de outros atributos do solo

ESTUDIO DE LAS CONCENTRACIONES DE NITRÓGENO Y FÓSFORO EN AGUAS DEL EMBALSE DE LA COPA. TOCA - BOYACÁ

This study presents the concentrations of nitrogen and phosphorus in the tributaries of the waterbody and in the La Copa reservoir in the municipality of Toca, Boyacá. The possible causes of theincrease of nutrients in the water are described and the effect of this increase on the quality andavailability of the water source studied is established. It is defined if the reservoir, in general, hasself-purification capacity, based on the analysis of its tributaries and effluent. The methodology used was based on field work that made it possibleto identify the strategic points for taking water samples. These wereanalyzed at the Environmental Analysis Laboratory of the Universidadde Boyacá, using the techniques established in the Standard Methodsfor the Examination of Water and Wastewater.From the results, the trophic state of the reservoir was identified. Thecontributions of nitrogen and phosphorus from the tributaries causethe reservoir to be in a process of eutrophication; a high percentageof these nutrients are retained in the reservoir sediments, a matrixthat acts as a buffer. For future research, it is possible to implementmonitoring and modeling activities that will allow us to know moreprecisely the behavior of these nutrients, as a management tool forthe lentic body, in the search for environmental decision making regardingits potential and possible uses.Este estudio presenta las concentraciones de nitrógeno y fósforo en los afluentes del cuerpo de agua y en el embalse de La Copa delmunicipio de Toca, Boyacá. Se describen las posibles causas del aumento de nutrientes en el agua y se establece la afectación deese incremento en la calidad y disponibilidad de la fuente de agua estudiada. Se define si el embalse, de manera general, tiene capacidad de autodepuración, partiendo del análisis de sus afluentes y efluente. La metodología empleada se soportó en un trabajo de campo que permitió reconocer los puntos estratégicos para la toma de muestras de agua. Estas fueron analizadas en el Laboratorio de Análisis Ambiental de la Universidad de Boyacá, mediante las técnicas establecidas en el Standard Methods for the Examination of Water and Wastewater.A partir de los resultados, se identificó el estado trófico del embalse. Las contribuciones de nitrógeno y fósforo por parte de los afluentes hacen que el embalse se encuentre en proceso de eutrofización; un alto porcentaje de estos nutrientes se quedan retenidos en los sedimentos del embalse, matriz que cumple el papel de amortiguador. Para futuros trabajos de investigación es posible implementar actividades de seguimiento y modelación que permitan conocer con más precisión el comportamiento de estos nutrientes, como herramienta de gestión del cuerpo léntico, en la búsqueda de toma de decisiones ambientales frente a su potencial y usos posibles

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe

The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library

Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data

The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra

This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17)