ABSTRACT Introduction: The scientific problem starts from a vision of sustainability in developing countries and is summarized in how architectural design may contribute to improve the indoor thermal environment and to reduce energy in the Cuban climate. Objective: to demonstrate that it is posible to reduce the temperature in the inner spaces and so the energetic comsumption due to the use of artificial air conditioning in buildings through a specific architectural design, suitable for the weather, the urban context and the orientation. Methods: It has been structured in three units responding to specific objectives, which reflects the evolution of research techniques and methods, software and measurement equipment, at a lab and natural scales, as well as calibration and validation of simulation with respect to monitoring. Results: The proposed theoretical and methodological base focuses on sustainability of the built environment from the point of view of the developing countries, taking the Cuban case as a reference; they are proposed variables, parameters an indicators to evaluate the influence of urban morphology on the passive and active uses of sun and wind; it is characterized the urban context according to projected shadow; it is demonstrated the need to update the Cuban Standard; it is proposed a procedure for the qualitative evaluation of design solutions in a warm and humid climate, and simulation and monitoring results are calibrated and validated. Conclusions: In order to move towards sustainability in developing countries, it is necessary to satisfy basic needs. Cuban society has demonstrated to be highly resilient, but it should pay more attention to the influence of architectural and urban design on indoor thermal environment and energy consumption.

RESUMEN Introducción: El problema científico parte de una visión de la sustentabilidad en los países en desarrollo y se resume en ¿cómo el diseño arquitectónico puede contribuir a mejorar el ambiente térmico interior y reducir el consumo energético en las condiciones del clima de Cuba? Objetivo: demostrar que es posible reducir la temperatura en los espacios interiores y el consumo energético por climatización artificial en los edificios mediante un diseño arquitectónico específico, adecuado al clima, al contexto urbano y a la orientación. Métodos: Se ha estructurado en 3 unidades que responden a objetivos específicos y reflejan la evolución de los métodos y técnicas de investigación, el uso de software y equipos de medición a escala de laboratorio y natural, así como la calibración y validación de las simulaciones en relación con el monitoreo. Resultados: La base teórico-metodológica propuesta enfoca la sustentabilidad del medio construido desde el punto de vista de los países en desarrollo, tomando el caso cubano como referente; se proponen variables, parámetros e indicadores para evaluar la influencia de la morfología urbana en los usos pasivos y activos del sol y el viento; se caracteriza el contexto urbano según las sombras arrojadas; se demuestra la necesidad de actualizar la NC-2020; se propone un procedimiento para evaluar cualitativamente las soluciones de diseño en clima cálido-húmedo, y se calibran y validan los resultados de la simulación y el monitoreo. En conclusiones para avanzar hacia la sustentabilidad en los países en desarrollo es necesario satisfacer las necesidades básicas. La sociedad cubana ha demostrado ser altamente resiliente, pero debe brindar más atención a la influencia del diseño arquitectónico y urbano en el ambiente térmico interior y el consumo de energía.

ABSTRACT Introduction: Schwannomas are encapsulated tumors that originate in the Schwann cells of the cranial nerves, being the most affected the VIII cranial nerve. The objective of this work is to expose the characteristics of a case with vestibular Schwannoma detected early in the otorhinolaryngology consultation. Clinical case: We present the case of a 44-year-old male patient who went to the otolaryngology clinic with an 8-year history of gait instability, vertigo, progressive hearing loss and tinnitus in the left ear. It was performed physical examination, normal otoscopy, Romberg, Babinski and Unterberger test with lateralization to the left. They were performed audiological and imaging studies, diagnosing vestibular Schwannoma. It is decided conservative treatment. Conclusions: Vestibular schwannoma is a rare tumor with unilateral auditory and vestibular symptoms. The suspicion and confirmation of early diagnosis with elements of the clinical history, contrasting audiological and imaging studies, guarantee the implementation of an individualized therapeutic option that contributes to the patient's quality of life.

RESUMEN Introducción: Los schwannomas son tumores encapsulados que se originan en las células de schwann de los nervios craneales, de los cuales el VIII nervio craneal es el más afectado. El objetivo del trabajo fue exponer las características de un caso con schwannoma vestibular detectado precozmente en la consulta de otorrinolaringología. Caso clínico: Se presenta el caso de un paciente masculino de 44 años que acude a consulta de otorrinolaringología con cuadro de 8 años de evolución con inestabilidad para la marcha, vértigo, hipoacusia progresiva y acúfeno en el oído izquierdo. Al examen físico, otoscopía normal, prueba de Romberg, Babinski y Unterberger con lateralización hacia la izquierda. Se realizan estudios audiológicos y de imágenes, diagnosticándose schwannoma vestibular. Se decide tratamiento conservador. Conclusiones: El schwannoma vestibular es un tumor infrecuente con síntomas auditivos y vestibulares unilaterales. La sospecha y confirmación del diagnóstico precoz con elementos de la historia clínica, estudios audiológicos e imagenológicos contrastados, garantizan implementar una opción terapéutica individualizada que contribuye a la calidad de vida del paciente.

ABSTRACT Introduction: The objective on this investigation was to create for Cuba the mineragenic maps on 1:250000 scale for weathering regolites and the geotectonic structures; also an universal nomenclature for the weathering rocks, the whole country being investigated in 2015-2019 according to project I+D "Mapa Mineragénico de Cuba" Phase I (Code 613490) and Phase II (Code 613740) of the Program of Science, Technology and Innovation of National Interest: Integral characterization of the Geology of Cuba, whose results compose this proposal. Methods: Beginning with the bibliographical search in retrospect up to 1807, continued by geologic, geophysical works, lithologic, petrographic, mineralogical and chemical-analytic for Fe, Ni, Co, Si, Al, Mg, Cr, Mn, Ti, Ba, Cu, Pb, Zn, Sr, Li, Sn, V, Ca, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; 130 mineralogical DRX; 3768 km of itineraries, the taking and documentation of 744 samples and 523 spectrometric measurements of U, Th, K with the spectrometer RS-230 BGO Super-Spec. Results: Two mineragenic maps: that of the weathering and the general one of IRM on scale 1:250000 of Cuba, and universal nomenclature for classification and systematic of the weathering rocks. The geotectonic scenarios and types of weathering regolites were typified and categorized according to their productivity and potentiality in mineral resources (IRM and metal-bearing), as well as litho-tectonic and mineragenic cartographies on scale 1:250000 of Cuba based on the Global Tectonic, results demanded for the Geologic Service of Cuba and useful for diverse objectives and branches of the Economy, Teaching and the Scientific Investigation in the country.

RESUMEN Introducción: El objetivo de la investigación fue resolver para Cuba los mapas mineragénicos a escala 1:250000 de las regolitas de meteorización y de las estructuras geotectónicas, así como un nomenclador universal de las rocas de la meteorización, investigándose todo el país en 2015-2019 según proyecto I+D “Mapa Mineragénico de Cuba”. Fase I (Código 613490) y Fase II (Código 613740) del Programa de Ciencia, Tecnología e Innovación de Interés Nacional: Caracterización Integral de la Geología de Cuba, cuyos resultados componen esta propuesta. Métodos: Se comenzó por la búsqueda bibliográfica con retrospectiva hasta 1807, seguida por trabajos geológicos, geofísicos, litológicos, petrográficos, mineralógicos y químico-analíticos para Fe, Ni, Co, Si, Al, Mg, Cr, Mn, Ti, Ba, Cu, Pb, Zn, Sr, Li, Sn, V, Ca, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; 130 DRX mineralógicas; 3768 km de itinerarios, toma y documentación de 744 muestras y 523 mediciones espectrométricas de U, Th, K con el espectrómetro RS-230 BGO Super-Spec. Resultados: Dos mapas mineragénicos: de la meteorización y general de RMI a escala 1:250000 de Cuba, y un nomenclador universal para clasificación y sistemática de rocas de la meteorización. Se tipificaron y categorizaron los escenarios geotectónicos y tipos de regolitas de meteorización por su productividad y potencialidad en recursos minerales (RMI y metalíferos), aportando cartografías tectónico-litológicas y mineragénicas a escala 1:250000 de Cuba basado en tectónica global, resultados demandados por el Servicio Geológico de Cuba y útiles para diversos objetivos y ramas de la Economía, la Docencia y la Investigación Científica del país.

ABSTRACT Introduction: In order to justify the diplomatic decision of the United States, two scientific articles were published in medical journals that attempt to support the idea that, in Havana, there was an attack aimed at US embassy personnel. Objective: To prove the lack of scientific consistency in two investigations of non-independent case series on the health symptoms of United States diplomats in Havana. Method: A documentary analysis of two publications of case series is carried out. Diagnostic hypotheses are evaluated. Results: There is wide overlap between the two series in terms of shared patients and in contrast there are some differences in the clinical data that exceed what was expected. Conclusions: In both publications the semiographic wealth of symptoms and psychosocial information are wasted. More emphasis is placed on arguments associated with the fetishism of technology expressed in the interpretation of nonspecific findings. The analysis of clinical data allowed us to see that it is a heterogeneous group of people whose health complaints have been brought together by the interaction of other contextual psychosocial factors.

RESUMEN Introducción: Con el propósito de justificar la decisión diplomática de los Estados Unidos, se publicaron dos artículos científicos en revistas médicas que intentan sostener la idea de que en La Habana hubo un ataque dirigido a personal de la embajada estadounidense. Objetivo: Demostrar la falta de rigor científico en dos investigaciones de series de casos no independientes sobre los síntomas de salud de diplomáticos de los Estados Unidos en La Habana. Método: Se realiza un análisis documental de dos publicaciones de series de casos. Se evalúan hipótesis diagnósticas. Resultados: Existe superposición amplia entre las dos series en cuanto a pacientes compartidos y en contraste se presentan algunas diferencias en los datos clínicos que superan lo esperado. Conclusiones: En ambas publicaciones se desaprovecha la riqueza semiográfica de síntomas y la información psicosocial. Se enfatiza más en argumentos asociados al fetichismo de la tecnología expresado en la interpretación de hallazgos inespecíficos. El análisis de datos clínicos permitió ver que se trata de un grupo heterogéneo de personas cuyas quejas de salud han sido reunidas por la interacción de otros factores psicosociales contextuales.

Abstract The city of Chiapa de Corzo located in the center of the state of Chiapas, is located in one of the most active seismic regions of Mexico. Local soil conditions have determined the seismic amplification of the site creating patterns in the damage observed after the occurrence of major earthquakes, such as the one that occurred on October 6thof 1975 that provoked radical changes in the habitants of the city, and the most recent of September 7 of 2017 of Mw 8.2.This paper presents a proposed seismic zoning for regions without studies of environmental vibration through a simplified methodology, which constitutes a variable to evaluate the physical vulnerability by exposure of constructions in cities with homogeneous constructive systems in materials, ages and pathologies. The proposed methodology uses geological parameters, soil and the inclusion of two crucial variables such as flood zones and historical damage by earthquake. According to the results of the algebra of maps were obtained two zones, a higher amplification where 85% of the damage were recorded for both earthquakes. The main inputs were digital cartography, field trips to identify the constructive pathologies of the structures that presented damage and processing through GIS-type software. Finally, the vulnerability was determined by exposure to seismic amplification in each block in the urban area of Chiapa de Corzo, using the amplification regions as a determinant variable to describe vulnerable constructions by exposure. For risk management this technique allows select the houses that must be reinforced, repaired or built with higher safety standards.

Resumen La ciudad de Chiapa de Corzo ubicada en el centro del estado de Chiapas se encuentra en una de las regiones sísmicas más activas de México. Las condiciones locales del suelo han determinado la amplificación sísmica del lugar creando patrones en los daños observados tras la ocurrencia de sismos importantes, como el sucedido el 06 de octubre de 1975 que provocó cambios radicales en los habitantes de la ciudad, y el más reciente del 07 de septiembre de 2017, de magnitud 8.2 Mw. En este trabajo se presenta una propuesta de zonificación sísmica para regiones donde no existen estudios de vibración ambiental a través de una metodología simplificada, la cual constituye una herramienta para evaluar la vulnerabilidad física por exposición de las construcciones en ciudades con sistemas constructivos homogéneos en materiales, edades y patologías. La metodología propuesta emplea parámetros geológicos, edafológicos y la inclusión de dos variables cruciales como son las zonas inundables y los daños históricos por sismo. De acuerdo con los resultados del álgebra de mapas se obtuvieron dos zonas, una de mayor amplificación en donde se registraron el 85% de los daños para ambos sismos. Los insumos principales fueron cartografía digital, recorridos en campo para identificar las características constructivas de las estructuras que presentaban daños y procesamiento a través de software tipo SIG. Finalmente se determinó la vulnerabilidad por exposición a la amplificación sísmica en cada manzana en la zona urbana de Chiapa de Corzo, utilizando las regiones de amplificación como una variable determinante para denominar las construcciones vulnerables por exposición. Para gestión de riesgo esta técnica permite seleccionar las viviendas que deben ser reforzadas, reparadas o construidas con estándares de seguridad más altos.

Background: The Chilean allocation system for liver transplantation (LT) uses the MELD/PELD score to prioritize candidates on the waiting list. Aim: To assess if the Chilean allocation system for LT is equitable for pediatric candidates compared to their adult counterparts. Material and Methods: We used the Public Health Institute's registry between October 2011 and December 2017. We analyzed candidates with chronic hepatic diseases listed for LT. The primary outcome was the cadaveric liver transplantation (CLT) rate. Secondary outcomes were death or disease progression in the waiting list and living donor liver transplant (LDLT) rate. Results: We analyzed 122 pediatric and 735 adult candidates. Forty one percent of pediatric candidates obtained a CLT compared to 48% of adults (p = NS). Among patients aged under two years of age, the access to CLT on the waiting list there was 28% of CLT, compared to 48% in adults (p = 0.001). Fifty-seven percent of candidates aged under two years were listed for cholestatic diseases, obtaining a CLT in 18% and requiring a LDLT in 49%. The median time in the waiting list for CLT was 5.9 months in pediatric candidates and 5.1 in adults, while the median time to death in the waiting list was 2.8 and 5.6 months, respectively. The mortality rate at one year in candidates under two years old was 38.1% compared to 32.5% in adults. Conclusions: Pediatric candidates with chronic liver diseases, especially under two years of age, have greater access difficulties to CLT than adults. Half of the pediatric candidates die on the waiting list before three months. The mortality among candidates under two years of age in the waiting list is excessively high.

RESUMEN Las variaciones locales del tipo de suelo y la topografía en menor medida, determinan la amplificación sísmica y han establecido un patrón en los daños observados durante grandes terremotos, como el que se produjo el 06 de octubre de 1975 y el 07 de septiembre de 2017Mw 8.2, siendo el más importante en la historia sísmica del último siglo en la región. Con estas bases se realiza un análisis para identificar la participación del espesor de sedimentos en la amplificación sísmica en la zona urbana de Chiapa de Corzo, Chiapas. Para obtener el espesor en el área de estudio se utilizaron los períodos fundamentales de vibración del suelo obtenidos por Salgado et al. (2004), que varían entre 0.14 s y 0.39 s. Además, a través del modelo utilizado por Newmark y Rosenbleuth (1976), se determinó la variación de los espesores de sedimentos que conducen el efecto de sitio en la zona, para lo cual se considera una velocidad media de onda de corte de 150 m/s. Finalmente, mediante el uso de software tipo GIS, se elaboró un mapa que representa los espesores de sedimentos en la ciudad de Chiapa de Corzo, que oscilan entre 7.12 m y 14.62 m y se hizo una correlación espacial con los daños históricos por sismo en la ciudad.

ABSTRACT Local variations in soil type and (to a lesser extent) topography determine seismic amplification, thereby establishing spatial patterns in the damages caused by large earthquakes, such as the two that occurred in Chiapas, Mexico on 6 October 1975 and 7 September 2017. The latter, of Mw 8.2, was the region's strongest during the last 100 years. Based upon damage patterns, an analysis was made to identify the effects of sediment thickness and type upon seismic amplification in the urban zone of Chiapa de Corzo, Chiapas. Salgado et al, (2004) had shown that the fundamental periods of soil vibration in the city vary from0.14 s to0.39 s. From those periods, and using the model presented in Newmark and Rosenbleuth (1976), with an average shear-wave velocity of150 m/s, the variation of the sediment thicknesses that cause site effects in the area was determined. The thicknesses ranged between 7.12 and 14.6 m. Finally, through the use of a map prepared with GIS software, a spatial correlation was made with the historical earthquake damage recorded within the city.

Summary: The cocoa provides significant levels of carbon (C) and nitrogen (N) by the leaf litter; the change of agronomic management causes variation in the contents of these elements in the soil. The objective was to evaluate the variations of the isotopes of δ13C and δ15N between two types of cocoa (CCN51 and Nacional), located in three soil orders in the province of El Oro, Ecuador. Thirty soil samples of 0.30 m deep and 25 samples of leaf litter were taken and the abundance of the isotopes of δ13C and δ15N were analyzed. The data were analyzed including two factors, cocoa types (CCN51 and National) and order of soils (Alfisol, Entisol and Inceptisol). The results showed that the ranges of the isotope of δ13C in soil were -23.81% (CCN51, Entisol) to -26.46% (National, Entisol) and in leaf litter -27.21% (CCN51, Alfisol) to -29.86% (National, Inceptisol). The ranges of the isotope of δ15N in soil were of 7.96% (National, Entisol) and 10.48% (National, Alfisol) and in leaf litter of 4.85% (National, Entisol) to 8.38% (CCN51, Alfisol). The averages of the δ13C in the soil were plants type C3. The values of δ15N in litter and soil was an indicator of low incidence of fertilizers nitrogenous origin inorganic in National and high mineralization of N in CCN51.

Resumen: El cacao aporta niveles significativos de carbono (C) y nitrógeno(N) por las hojarascas; el cambio de manejo agronómico ocasiona variación en los contenidos de estos elementos en el suelo. El objetivo fue evaluar las variaciones de los isotopos de δ13C y δ15N, entre dos tipos de cacao (CCN51 y Nacional), localizados en tres órdenes de suelo en la provincia de El Oro, Ecuador. Se tomaron 30 muestras de suelo a 0.30 m de profundidad y 25 muestras de hojarasca y se analizó la abundancia de los isótopos de δ13C y δ15N. Los datos se analizaron considerando dos factores, tipos de cacao (CCN51 y Nacional) y orden de suelos (Alfisol, Entisol e Inceptisol). Los resultados muestran que los rangos del isotopo de δ13C en suelo fueron de -23.81% (CCN51, Entisol) a -26.46% (Nacional, Entisol) y en hojarasca de -27.21% (CCN51, Alf isol) a -29.86% (Nacional, Inceptisol). Los rangos del isotopo de δ15N en suelo fueron de 7.96% (Nacional, Entisol) y 10.48% (Nacional, Alfisol) y en hojarasca de 4.85% (Nacional, Entisol) a 8.38% (CCN51, Alfisol). Los promedios del δ13C en el suelo correspondieron a plantas tipo C3. Los valores de δ15N en suelo y hojarasca fue un indicador de baja incidencia de fertilizantes nitrogenados de origen inorgánico en Nacional y de alta mineralización alta del N en CCN51.

Abstract: The present article shows a dynamic analysis of the behavior experienced on the educative pico-satellite CanSat. The structure model was analyzed through the theory of the Finite Element, for the study of the structure we used the ANSYS platform, which allowed us to predict the answer of the structure during its launching, as well as the CanSat drop. We determined the first 15 modal forms and their natural corresponding frequencies. The analysis was performed considering the acceleration force of 30 g, on a vertical direction. We analyzed the concentration states of stress, defect and the values of natural frequencies. On this work, we discuss the results obtained in the structure configuration when this is transported by a hexacopter drone with a motor operation frequency of 480 Hz.

Resumen: El presente artículo muestra un análisis dinámico del comportamiento que experimenta la estructura de un pico-satélite educativo CanSat. El modelo de la estructura se analizó por medio de la teoría del elemento finito, para el estudio de la estructura se utilizó la plataforma de ANSYS, la cual, permitió predecir la respuesta de la estructura durante el lanzamiento, así como el descenso del CanSat. Se determinaron las primeras 15 formas modales y sus frecuencias naturales correspondientes. Los análisis se realizaron considerando fuerzas de aceleración de 30 g, en la dirección vertical. Se analizaron los estados de concentración de esfuerzos, deformaciones y los valores de las frecuencias naturales. En el trabajo se discuten los resultados obtenidos de la configuración estructural cuando es transportada en ascenso por un dron hexacoptero con una frecuencia de operación de los motores de 480Hz.

With the objective of updating the criteria on agrarian sustainability of it is proposed the adaptation of a method from 3 labor frameworks for measuring agricultural systems sustainability. It was established a systematic review of the scientific information, with an assessment instrument (surveys) or type of sample (soil, water or biomass) to be taken from agricultural systems. The criteria are structured at the farm level, where the soil resource, water management, diversity of production, education and training are considered to be of higher incidence in the sustainability, producing indicators approved by a panel of experts whose contribution is validated with the coefficient alpha of Cronbach. Weight assignment to the indicators is contributed according to the scientific literature, it continues with the linear normalization of 0 to 1; In addition an analysis of main components is proposed to reduce indicators and to perform radial graphs for its examination by domains and criteria with the purpose of improving its qualification in the future.

Con el objetivo de actualizar los criterios sobre la sostenibilidad agraria se propone la adaptación un método a partir de tres marcos de trabajo para la medición de la sostenibilidad de sistemas agrarios. Se estableció una revisión sistemática de la información científica, con el instrumento de evaluación (encuestas) o tipo de muestra (suelo, agua o biomasa) a tomar de los sistemas agrarios. Los criterios se estructuran a nivel de finca, donde el recurso suelo, manejo del agua, diversidad de la producción, educación y capacitación se consideran de mayor incidencia en la sostenibilidad, se generan indicadores aprobados por un panel de expertos cuyo aporte es validado con el coeficiente de Alpha de Cronbach. Se aporta la asignación de pesos a los indicadores en función de la literatura científica, prosigue con la normalización lineal de 0 a 1; además se propone un análisis de componentes principales para reducir indicadores y realizar gráficos radiales para su examen por dominios y criterios con la finalidad de mejorar su calificación en el futuro.

ABSTRACT Soil sampling is an important stage of digital soil mapping. The objective of this study was to characterize the spatial design of soil sampling using soil apparent electrical conductivity (ECa) and its optimized spatial sampling. For the characterization, it was used the Spatial Simulated Annealing (SSA) technique, incorporated on the software SANOS 0.1, and the method of response surface sampling design on the software ESAP 2.35. The ECa was measured at 1,887 points in an area of 6 ha located in the northwestern region of Spain. The EM38-DD equipment (Geonics Limited 2005) was used at 2 depths: vertical dipole (1.5 m effective measurement depth) and horizontal dipole (0.75 m effective measurement depth). Semivariogram showed trend for ECa in vertical dipole (ECa-V) and ECa in horizontal dipole (ECa-H). Software SANOS 0.1 and ESAP 2.35 were used to obtain the 40-point sampling scheme, using the 2 schemes (SANOS and ESAP). ECa-V estimation values at the 1,887 points were calculated with residual ordinary kriging. The sampling scheme obtained from ESAP was better than with SANOS.

Resumo O objetivo deste trabalho foi avaliar os horizontes diagnósticos superficiais e quantificar os valores de δ13C em perfis de Cambissolos localizados em regiões de elevada altitude, em Santa Catarina, bem como propor a utilização complementar desse atributo no Sistema Brasileiro de Classificação de Solos (SiBCS). Foram realizadas coletas de amostras de horizontes superficiais de 24 perfis modais para a caracterização de atributos físicos e químicos. Para a determinação do δ13C, as coletas foram feitas nas camadas de 0,0-0,10, 0,10-0,20, 0,20-0,30, 0,30-0,40, 0,40-0,50, 0,50-0,60, 0,60-0,80 e 0,80-1,00 m. Predominaram os Cambissolos Háplicos com horizonte diagnóstico superficial A moderado e elevados teores de carbono orgânico total (COT). Os elevados valores de COT, no entanto, frequentemente não foram suficientes para classificação dos horizontes superficiais como A húmico, em razão de sua pequena espessura. Nos solos classificados como A húmico, os valores de δ13C revelaram pequena alteração na assinatura isotópica, indício de manutenção da vegetação; enquanto nos solos com A moderado observaram-se alterações decorrentes do cultivo. Sugere-se o uso de δ13C como atributo complementar para o SiBCS, e que o atributo profundidade seja desconsiderado, para fins de classificação, no caso de: alterações no uso do solo em áreas com declividade superior a 8%, solos rasos e pouco profundos, textura argilosa a muito argilosa e teores de COT superiores a 3%.

Abstract The objective of this work was to evaluate superficial diagnostic horizons and to quantify δ13C in Inceptisol profiles on the highlands of the state of Santa Catarina, Brazil, as well as to propose the complementary use of this attribute in the Brazilian System of Soil Classification (SiBCS). Samples of superficial horizons were collected to characterize physical and chemical attributes of 24 modal profiles. For the evaluation of δ13C, the samples were taken at the layers of 0.0-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, 0.50-0.60, 0.60-0.80, and 0.80-1.00 m. Haplic Inceptisols with moderate A superficial diagnostic horizon and high total organic carbon (TOC) content predominated. The high TOC values, however, were often not enough to classify the superficial horizon as humic A, due to its small thickness. In soils with humic A, δ13C values revealed little alteration in the isotopic signature, which indicates vegetation maintenance; whereas in the soils with moderate A, alterations occurred due to cultivation. The use of δ13C to complement the SiBCS is suggested, and depth should be disregarded for classification in the case of: changes in land use in areas with slopes above 8%, shallow or small-depth soils, clayey to very clayey texture, and TOC contents above 3%.

RESUMO Conversões da cobertura vegetal decorrentes do manejo podem alterar o estoque de carbono e a abundância natural de 13C. Objetivou-se avaliar o estoque de C e a abundância natural de 13C em áreas de sucessão de floresta (F) e pastagem (P), com diferentes tempos de uso, na Floresta Atlântica no Estado de Santa Catarina. Sete sucessões de uso entre F e P foram definidas por fotografias aéreas tomadas em 1957, 1978 e 2008, entrevistas com moradores e escolha de áreas com florestas em estádio médio de regeneração. As sucessões foram identificadas como FFP, FPF, FFP, FPP, PFF, PPF, PPP, em que a primeira letra se refere ao uso observado em 1957; a segunda, em 1978; e a terceira, em 2008. Foram coletadas amostras de solo nas camadas de 0,00-0,10; 0,10-0,20; 0,20-0,30; 0,30-0,40; 0,40-0,50; 0,50-0,60; 0,60-0,80 e 0,80-1,00 m. Quantificaram-se os teores de carbono orgânico total (COT), abundância de C (δ13C), densidade do solo (Ds) e estoque de carbono (ECOT). A conversão de F em P proporcionou aumento da Ds e reduções nos teores de COT e no ECOT do solo. O maior valor de ECOT ocorreu nas áreas atualmente ocupadas por florestas, mesmo tendo sido utilizadas como pasto anteriormente. Áreas de floresta secundária tenderam, em relação aos teores de COT, a um novo equilíbrio, dado que foram verificados teores de COT superiores aos quantificados em áreas de floresta primária. As áreas de floresta e pastagem, com diferentes idades de uso e nas diferentes profundidades de solo avaliadas, evidenciaram respostas na δ13C, resultando em diferentes assinaturas isotópicas, confirmando a mudança de uso de plantas C3 para C4. Em pastagens com 50 anos de uso, na camada de 0,00-0,10 m, 66 % do COT do solo ainda é derivado da floresta original. A análise de componentes principais (ACP) indicou que o COT foi o atributo que melhor discriminou as alterações em razão do uso da terra, nas diferentes camadas de solo.

ABSTRACT Conversions of plant cover resulting from management practices may alter carbon storage and the natural abundance of 13C. The aim of this study was to evaluate C stocks and natural abundance of C (δ13C) in areas of forest (F) and pasture (P) sequences with different times of usage in an Atlantic Forest area, Santa Catarina, Brazil. Seven usage sequences of forest (F) and pasture (P) were defined through aerial photographs taken in 1957, 1978, and 2008; through interviews with residents; and through choice of areas with forests in an intermediate stage of regeneration. The sequences were identified as FFP, FPF, FFP, FPP, PFF, PPF, and PPF; in which the letters F or P refer to the usage observed in the years 1957, 1978, and 2008, respectively. Soil was sampled at the depths of 0.00-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, 0.50-0.60, 0.60-0.80, and 0.80-1.00 m. Natural abundance of soil 13C (δ13C), total organic carbon (TOC), bulk density (BD), and carbon stock (CST) were quantified. Conversion of forest to pasture led to an increase in BD and reduction in TOC and CST in the soil. The highest CST value was observed in areas currently occupied by forest, even when previously used as pasture. The TOC in the areas with secondary forest showed a tendency toward new equilibrium, since TOC values were higher than those observed in primary forest areas. The forest and pasture areas showed variation in the isotopic signatures of δ13C in the different land use times and soil depths, confirming the shift in cultivation from C3 to C4 plants. In pasture areas with 50 years of use, at the 0.00-0.10 m depth, 66 % of soil TOC is still derived from the original forest. Principal component analysis (PCA) indicated that TOC was the property that best discriminated the changes related to land use in the different soil depths.

A estimativa de perdas de solo é fundamental para o planejamento conservacionista. Com essa finalidade, destaca-se no Brasil o uso da Equação Universal de Perdas de Solo (USLE), para cuja utilização há escassez de dados obtidos de acordo com o método-padrão desse modelo. Entre os fatores que compõem a USLE, a erodibilidade do solo (fator K) é de difícil obtenção em razão da necessidade de conduzir experimentos em campo por longo tempo sob chuva natural. Com o objetivo de quantificar a erodibilidade do solo em um Cambissolo Húmico em Lages, SC, utilizando-se do método-padrão da USLE, quantificaram-se a erosividade (EI30) das chuvas naturais e as respectivas perdas de solo durante o período de 1993 a 2012. A erodibilidade foi determinada pelo quociente entre essas variáveis e pela regressão linear simples dessas. O valor de erodibilidade anual estimado pelo quociente e pela regressão linear simples entre as perdas de solo e as erosividades foi respectivamente de 0,0175 e 0,0172 Mg ha h ha-1 MJ-1 mm-1. A erodibilidade nos períodos de primavera-verão e outono-inverno apresentou pequenas variações em relação à média anual. A erodibilidade mensal variou de 0,0083 Mg ha h ha-1 MJ-1 mm-1 no mês de dezembro a 0,0241 Mg ha h ha-1 MJ-1 mm-1, no mês de abril. Ao longo do período de tempo avaliado, a erodibilidade anual evidenciou maior incremento nos anos iniciais e menor incremento nos anos finais.

Estimation of soil loss is critical to conservation planning. To make that estimation, use of the Universal Soil Loss Equation (USLE) is prominent in Brazil. For use of the USLE, there is a shortage of data obtained according to the standard method of this model. Among the factors that compose the USLE, soil erodibility (K factor) is difficult to obtain due to the need to conduct experiments in the field for a long time under natural rainfall. Aiming to quantify soil erodibility in a Humic Inceptisol in Lages, Santa Catarina, Brazil, with the use of the standard method of USLE, we quantified the erosivity (EI30) of natural rainfall and respective soil loss for the period 1993-2012. Erodibility was determined by the ratio between these variables and by simple linear regression of the same variables. Annual erodibility values, estimated by the ratio and by simple linear regression between soil loss and erosivity, were 0.0175 and 0.0172 Mg ha h ha-1 MJ-1 mm-1, respectively. The erodibility in spring-summer and autumn-winter showed small variations in relation to the annual average. The monthly erodibility ranged from 0.0083 Mg ha h ha-1 MJ-1 mm-1 in December to 0.0241 Mg ha h ha-1 MJ-1 mm-1 in April. Throughout the time period evaluated, annual erodibility exhibited a greater increase in the initial years and a smaller increase in the final years.