Resumo Objetivo da Investigação: Analisar a vulnerabilidade natural à perda do solo do médio curso da bacia hidrográfica do Rio Apodi Mossoró. Metodologia: Realizou-se a média aritmética das variáveis do meio físico em ambiente SIG. Resultados: O resultado mostrou que a bacia se encontra na classe Medianamente Estável/Vulnerável, com valor médio de 2,04, na escala de 1,0 a 3,0. Cerca de 25% da área apresentou classe considerável entre medianamente vulnerável a vulnerável. Sugere-se que, para essas áreas, sejam criados critérios que limitem o uso e ocupação, tendo como suporte as legislações ambientais em vigor, visando a conservação e/ou restauração dos sistemas naturais ainda existentes. Originalidade/Valor: O artigo apresenta um método visando identificar a vulnerabilidade natural em bacias hidrográficas de regiões semiáridas, tendo como suporte o uso de geotecnologias. A partir desse método, é possível identificar quais condicionantes do meio físico mais influenciam na vulnerabilidade natural, identificando áreas mais propícias à preservação/conservação do ambiente.

Abstract Research Purpose: To analyse the natural vulnerability to soil loss of the middle course of the Apodi Mossoró River watershed/RN. Methodology: The arithmetic mean of the variables of the physical environment was performed in a GIS environment. Findings: The result showed that the basin is in the Moderately Stable/Vulnerable class, with a mean value of 2.04, on a scale of 1.0 to 3.0. About 25% of the area presented considerable class between moderately vulnerable to vulnerable. It is suggested that, for these areas, to create criteria be created that limit the use and occupation, having as support the environmental legislation in force, aiming at the conservation and/or restoration of the natural systems that still exist. Originality/Value: The article presents a method aimed at identifying the natural vulnerability in watersheds of semi-arid regions, supported by the use of geotechnologies. From this method, it is possible to identify which conditioning factors of the physical environment most influence the natural vulnerability, identifying areas more conducive to the preservation/conservation of the environment.

ABSTRACT Mining is a significant driver of soil mobilization, which impacts its physical, chemical, and biological properties. Changes in land-use affect the distribution of organic matter fractions in stable aggregates, a process that is still poorly understood, especially in drastically altered areas. Recovering and monitoring soil quality to ensure the sustainable development of agricultural crops in these areas after mining is challenging. This study aimed to evaluate the influence of agronomic practices in soil rehabilitation in a bauxite-mined area after three years of field experiment installations through an assessment of organic properties in soil and aggregate classes; an attempt was also made at proposing and elaborating a Soil Quality Index (SQI), which encompasses the soil’s physical, chemical, and organic properties. Different combinations of fertilization treatments and ground cover plants intercropping with coffee were evaluated as rehabilitation practices. The results showed that after three years of rehabilitation, when organic (OF), chemical (CF), and OF+CF fertilizers were applied to the areas of coffee intercropped with Brachiaria (B), they provided higher C and N contents to the soil and aggregates classes, as well as the compartments of soil organic matter (SOM). The minimum set of soil quality indicators for reclaimed bauxite-mined areas was composed of organic indicators: labile organic carbon (LOC) and mineral-associated organic matter (C-MOM); chemical indicators including pH and effective cation-exchange capacity (t), and physical indicators such as the bulk density (BD) and stable aggregates index in water (SAIW). The t and pH were the variables most sensitive to the management systems implanted during the rehabilitation of the mined area, and, therefore, were considered the best indicators of soil quality. Brachiaria was the cover plant that contributed most to improving the soil quality of mined bauxite areas by increasing the SQI, especially when fertilized. In general, when applied to the Brachiaria, the OF+CF fertilization presented a SQI of 0.78, differing statistically from that of the natural vegetation (1.00). Fertilizers and cover crops in association with coffee in the bauxite-mined areas improved the physical, chemical, and organic properties of the soil, thus representing a viable option for reconditioning mineral exploration areas. mobilization landuse land use understood challenging bauxitemined classes , (SQI) soils s OF, OF (OF) CF, CF (CF) OFCF B, B (B) SOM. SOM . (SOM) LOC (LOC mineralassociated associated CMOM MOM (C-MOM) cationexchange cation exchange t, (t) BD (BD SAIW. SAIW (SAIW) therefore fertilized general 078 0 78 0.78 1.00. 100 1.00 1 00 (1.00) (SQI (OF (CF (B (SOM (C-MOM (t (SAIW 07 7 0.7 10 1.0 (1.00 0. 1. (1.0 (1. (1 (

Abstract In the present study, the approximate fractal morphometry of spherical-type essential oil microemulsions was performed. The geometric fractal characterization was carried out by a recently published continuous half-fractal model which allowed to model microemulsions as systems in their stable thermodynamic equilibrium phase with high degree of homogeneity. Regarding the characteristic of high homogeneity an equation was developed to roughly describe the volume fractal dimension and the fractal volume of two special cases elaborated from Rosmarinus officinalis and Melaleuca alternifolia previously investigated. In addition, referring to the characteristic of high homogeneity, it was possible to approximate the fractal dimension of area and the fractal area for each microemulsion. Our numerical estimates showed coherence with the principles of Hausdorff-Besicovitch geometry and with the experimental evidence about the physical dimension as a non- integer dimension.

Resumen Introducción: El Alzheimer es la forma más común de demencia y una de las primeras causas de discapacidad. Objetivo: Describir si en pacientes con Alzheimer el acompañamiento familiar, en comparación con el abandono, ralentiza la evolución de esta enfermedad. Metodología: Revisión integrativa. Se seleccionaron artículos de los últimos cinco años, en idioma inglés, español y portugués, disponibles en las bases de datos PubMed, EBSCO HOST, Scielo, Clinicalkey, Google Académico; se utilizaron los términos MeSH y DeCS: Alzheimer, Continuity of Patient Care, family, Psychosocial Support Systems, junto con los operadores booleanos AND y OR. Se efectuó lectura crítica con las escalas STROBE y AMSTAR, y se clasificó el nivel de evidencia y grado de recomendación. Resultados: El diario vivir del cuidador evidencia sobrecarga física y psicológica que llevan a desistir del cuidado de los adultos que padecen Alzheimer. Conclusión: Una red de apoyo estable garantiza mejores cuidados y educación que ralentizan la enfermedad.

Abstract Introduction: Alzheimer is the most common form of dementia and one of the first causes of disability. Objective: To describe if in patients with Alzheimer’s disease the family accompaniment, compared to the abandonment, slows the evolution of this disease. Methodology: Integrative review. Selected articles from the last five years, in English, Spanish and Portuguese, available in the PubMed, EBSCO HOST, Scielo, Clinicalkey, Google academic databases, using the terms MeSH and DeCS: Alzheimer, Continuity of Patient Care, family, Psychosocial Support Systems, along with Boolean operators “AND” and “OR”. A critical reading was made with the STROBE and AMSTAR scales, and the level of evidence and degree of recommendation were classified. Results: The daily life of the caregiver shows physical and psychological overload that leads to giving up the care of adults suffering from Alzheimer. Conclusion: A stable support network ensures better care and education that slows the disease.

Abstract In the Agro-ecological Center “Las Cañadas” located in Huatusco, Veracruz, the agro-ecological management of production systems has been implemented for approximately 20 years, as an alternative to the negative effects caused by conventional agriculture; however, the beneficial effect and the magnitude with which each of these systems has contributed to the restoration of soil quality since its implementation is unknown. In the present work, the current state of the quality of the soil of the different agroecological production systems, as well as of the natural forest through its chemical and physical properties and the diagnosis of the state of soil fertility for crop production, were assessed. Composite soil samples were taken from the ten production systems, as well as from two areas of restored and natural vegetation, to determine their chemical and physical properties, the local inputs used in the fertilizer of the crops were also chemically characterized. In general, ecological production systems; through the addition of local organic matter, minimal tillage of the soil and complementary additions of inputs have contributed to the regeneration of the natural quality of the soil in its chemical properties, but the recycling of nutrients from local inputs is insufficient to cover the nutritional needs of crops for optimal production. Agroecological management has also contributed to the fact that physical properties such as microporosity, usable humidity and stable aggregates have managed to reach the original level in the soil.

Resumen En el Centro Agroecológico ‘Las Cañadas’ localizado en Huatusco, Veracruz, se implementó el manejo agroecológico de los sistemas de producción desde hace aproximadamente 20 años, como alternativa a los efectos negativos ocasionados por la agricultura convencional; sin embargo, se desconoce el efecto benéfico y la magnitud con la que cada uno de estos sistemas ha contribuido en la restauración de la calidad del suelo desde su implementación. En el presente trabajo se valoró el estado actual de la calidad del suelo de los diferentes sistemas agroecológicos de producción, así como del bosque natural a través de sus propiedades químicas y físicas y diagnosticar el estado de la fertilidad del suelo para la producción de cultivos. Se tomaron muestras compuestas de suelo de los diez sistemas de producción, así como de dos áreas de vegetación restaurada y natural, para determinar sus propiedades químicas y físicas, los insumos locales utilizados en el abonado de los cultivos también fueron caracterizados químicamente. En general, los sistemas ecológicos de producción; a través, de la adición de materia orgánica local, labranza mínima del suelo y adiciones complementarias de insumos han contribuido a la regeneración de la calidad natural del suelo en sus propiedades químicas, pero, el reciclaje de nutrientes a partir de los insumos locales es insuficiente para cubrir las necesidades nutrimentales de los cultivos para una óptima producción. El manejo agroecológico también ha contribuido a que propiedades físicas como microporosidad, humedad aprovechable y agregados estables hayan logrado alcanzar el nivel original en el suelo.

RESUMEN En Nariño, Colombia, el cambio de uso del suelo ha generado problemas de erosión, compactación, pérdida de la capa fértil del suelo, entre otros, siendo necesario buscar alternativas que minimicen estos impactos. El estudio se realizó con el objetivo de evaluar algunas de las propiedades físicas del suelo en un sistema agroforestal con Morella pubescens (Humb. & Bonpl. ex Willd.) Wilbur, en asocio con Smallanthus sonchifolius Poepp.) H.Rob, en la Granja Experimental Botana, municipio de Pasto, donde se analizó la densidad aparente, densidad real, porosidad total, distribución de agregados y estabilidad estructural del suelo. Los datos se obtuvieron en dos fases; fase 1 (f1) y fase 2 (f2) antes y después de la implementación del sistema agroforestal, respectivamente. Se utilizó un diseño de bloques completos al azar con tres tratamientos y tres repeticiones. Los tratamientos correspondieron a densidades de siembra T1: S. sonchifolius sembrado a 1x1m, T2:0.8x0.8m y T3:0.5x0.5m. M. pubescens fue establecido a 4 x 4m entre plántulas y a 9m entre líneas de M. pubescens y el testigo. Se presentaron diferencias estadísticas significativas entre f1 (testigo) y f2 (tratamientos), para las propiedades estabilidad estructural y distribución de agregados. El suelo sufrió un cambio en la estabilidad estructural pasando de ligeramente estable (0.97 D.P.M) en f1 a moderadamente estable (2.53 D.P.M), en f2. La distribución de agregados pasó de un 60% en f1 a un 70.3% en la f2. El manejo de sistemas agroforestales puede contribuir a mediano y largo plazo en la mejora de la estructura del suelo mediante la incorporación del material vegetal del componente arbóreo, la aplicación de una labranza mínima y la adición de materia orgánica.

ABSTRACT In Nariño, Colombia, land use has generated some problems such as erosion, compaction, lack of fertility, among others, so it is necessary to search for alternatives to mitigate these impacts. The objective of this study was to evaluate some physical properties of the soil in an agroforest system with Morella pubescens (Humb. & Bonpl. ex Willd.) Wilbur with Smallanthus sonchifolius (Poepp.) H.Rob, in the experimental farm of Botana, in the city of Pasto, Nariño, where the bulk density, real density, total porosity, structural stability properties and distribution of aggregates were analyzed. The datas were obtained in two phases: f1 and f2 before and after agroforestry system implementation, respectively. A randomized complete block design with three treatments and three replications were used. The treatments corresponded to plant densities, T1: S sonchifoliuos, sowed to 1x1m, T2:0.8x0.8m y T3:0.5x0.5m, with three replications. M pusescens was stablished to 4x4m between plants and 9 m between rows and the control (f1). The statistics have differences between f1 (control) and f2 (treatments), to the structural stability properties and distribution of aggregates. The ground suffered a structural stability change to stable lightly (0.97 D.P.M) in f1 to a stable moderate (2.53 D.P.M), in f2. The distribution of aggregates passed to 60% in f1 to 70.3% in f2, with a media aggregation status. The different agroforest systems management could help, in the long term, by improving the structure of the ground through the vegetal material of arboreal component, the application of a minimum farming and the addition of organic matter.

Abstract In different parts of the world, family is considered the main responsible for ensuring children the full enjoyment of their rights; also, family is recognized as the central core for children’s development. Even so, in exceptional situations, children need to be separated from their biological family. In those cases, alternative care is required. This study investigates two different types of alternative care: institutional care and family foster care. The aim of this paper is to review the existing literature on child development of children in those types of alternative care. The review was done through different scientific data base: Science Direct, SciELO, Redalyc, PubMed, DialNet y Academic Google, and using the following key words: “desarrollo infantile”, “familias de acogida temporal”, “institucionalización”, “child development”, “temporary family foster care”, “residential care”. With reference to the studies about temporary family foster care, the ones considered were those that made reference to family systems that took temporary care of a child until their judicial situation was solved. These were external families that have no bonds with the child. Those studies in which the families were pre-adoptive ones were not considered. Fifty-eight articles, published in the last seventeen years (from 2000 to 2017), were chosen. From this total, nineteen correspond to systematic revisions, four are reports from children organizations, while the remaining thirty-five correspond to empiric studies. The results of this paper are organized in two different sections: the first one makes reference to the conditions of life at an institution and the child development under these conditions, whereas the second one makes reference to temporary family foster care programs and the child development after the inclusion in these programs. As regards the first section, it is concluded that the institutional care shows the lack of an exclusive and stable affect figure, being the children exposed to unstable rotating caregivers with consistent bond disruption. These caregivers are described as unavailable to the children with minimal emotional and physical contact. Furthermore, the caregivers show lack of empathy and little responsiveness to child’s individual needs resulting in chronic emotional deprivation. At the same time, the above mentioned is closely related to the delays or difficulties that the development of these institutionalized children show in different areas: cognitive, intellectual, academic, socio-affective, emotional, physical-motor, cerebral and neurological. In the second section of the paper, the results of the studies on children development in temporary family foster care are described and the countries where evidence on these programs was found are presented. They show that there are significant and beneficial physical, emotional, socio-affective, behavioral, cognitive and intellectual changes in the development of institutionalized children after they enter temporary family foster care. Moreover, the development of children living in alternative care differs significantly from the one of those living with family foster care. The results also specify the characteristics that a temporary family foster care must have in order to facilitate the child’s development. It is concluded that children in institutional care show delays and maladaptation in various domains of development. Besides, the longer the child is institutionalized, the more his behavior is affected. The authors believe that these institutions are not the right places to raise children during a long period of time and they propose the need to prioritize temporary family foster care. The results underline the importance of family foster care programs as an alternative that could improve children´s development. Nevertheless, institutional care is still the predominant alternative worldwide for children without parental care. Finally, this systematic review aims to be a starting point for future research. The aspects that need to be deepen are highlighted.

Resumen El objetivo del presente trabajo fue realizar una revisión bibliográfica sobre el desarrollo de los niños y niñas bajo cuidados alternativos institucionales y de familias de acogida temporal. Se realizó en diversas bases de datos científicas: Science Direct, SciELO, Redalyc, PubMed, DialNet y Google Académico, utilizando las siguientes palabras claves: “desarrollo infantil”, “familias de acogida temporal”, “institucionalización”, “child development”, “temporary family foster care”, “residential care”. Fueron seleccionados 58 artículos, publicados en revistas científicas de los últimos 17 años (período 2000-2017). Se incluye una síntesis de sus resultados organizando a la misma en dos apartados: en el primero se hace referencia a las condiciones de vida en el ámbito institucional y al desarrollo infantil en dichas condiciones, y en el segundo, a los programas de familia de acogida temporal y al desarrollo tras la inclusión en estos programas. Se destacan los aspectos que restan profundizar.

Abstract Several studies have demonstrated that sugar-based nanocarriers are recommended to develop drug delivery systems since they are biocompatible and biodegradable and might improve the therapeutic index of currently used drugs by reducing their toxicity and enhancing their bioavailability. Therewith, this work studied the processing conditions to formation of a sugar-based nanocarrier denominated polymeric colloidal nanocarriers (PCN). It reports the impact of emulsifiers types and concentration, salt concentration and copolymers addition on physical stability and particle size distribution of a maltodextin-based PCN. In order to define the most stable formulation to produce the maltodextrin nanocarriers, 13 PCN formulations were evaluated in respect to kinetic stability, particle size distribution and morphology. The results demonstrated that to have a stable sugar-based PCN in silicone for at least 3 days, it is necessary to work with Poloxamer 188 as a copolymer, SF 1540 surfactant in a concentration proportional to the solid content and a salt concentration of 0.4 %.

Electric dipole moment (EDM) required for the relative motion of carbon nanotube (CNT) walls in nanoelectromechanical systems (NEMS) such as actuators and oscillators is studied by functionalization. Pristine (5,0) zigzag carbon nanotube with little inherent electric dipole moment (ì) were deformed by adding three -OH functional groups to its end rims. The properties of eight yielded isomers are studied. The Gibbs free energy calculations demonstrate that the eight structures are more stable than pristine CNT. The induced deformation resulted in charge imbalances which developed large electric dipole moments for each case. The values of dipole moments produced for all cases are calculated. The bandgap energy, conductivity, density of state (DOS) and IR spectra of these structures are also computed and analyzed. The study revealed that the location of the -OH positioning (site selectivity) which gives rise to different degrees of deformation has a significant impact on all of the above parameters, especially the magnitude and direction of the electric dipole moment. The functionalization produced large ì of about 6.9 D for 60 carbon atoms nanotube which is higher than in the previous study. Applying an external electric field to the isomers causes the CNTs with large dipole moments to either get attracted or repelled and hence physical movement or oscillation of the nanotube occurs. The frequency of this oscillation is in gigahertz scale.

RESUMO Esse estudo avaliou a influência dos sistemas agroflorestais e da agricultura tradicional sobre os atributos físicos e biológicos do solo, utilizando como referência uma área de floresta nativa em Paraty, RJ. Foram analisados os teores do carbono orgânico total do solo e suas frações oxidáveis, a estabilidade dos agregados, além da atividade e os teores de carbono e nitrogênio da biomassa microbiana do solo, na camada de 0-5 cm, em duas épocas (seca e chuvosa) distintas. Os sistemas agroflorestais e a agricultura tradicional mantêm níveis elevados de carbono orgânico total e seu armazenamento em frações mais estáveis. Quando comparados à área de Floresta, esses sistemas proporcionam as mesmas condições para a agregação do solo. A biomassa microbiana foi mais responsiva as variações de manejo e sazonalidade. A implantação de sistemas agroflorestais contribui para a formação de uma matriz agrícola mais diversificada, promovendo melhorias na qualidade do solo e conexão com os remanescentes florestais próximos.

ABSTRACT In the present study, we evaluated the influence of agroforestry systems and traditional agriculture on the physical attributes and biologicals of soil, using as reference a native forest area in Paraty, RJ. Levels of total soil organic carbon, as well as oxidizable fractions and aggregate stability, were analyzed, in addition to the activity and carbon and nitrogen content in the soil microbial biomass, in the 0-5 cm layer, in two distinct seasons (dry and rainy seasons). The agroforestry systems and traditional agriculture maintain high levels of total organic carbon and its storage in more stable fractions. These systems provide the same conditions as those of the forest area for the aggregation of the soil. The microbial biomass was more responsive to variations in management and seasonality. The deployment of agroforestry systems contributes to the formation of a more diversified agricultural matrix, promoting improvements in the soil quality and connection with the remaining adjacent forest.

Underground coal gasification (UCG) is the conversion of coal in situ into a usable synthetic gas. One of the major environmental concerns with UCG is the possibility of groundwater from the coal seam aquifer contaminating the shallow aquifers via hydraulic connections. The coal seam aquifers are usually confined aquifers but can have hydraulic connections to the shallow aquifers due to faults/fractures or any man-made connections, including boreholes. The aim of this paper is to study groundwater hydraulic connections across various aquifers at the UCG site at Majuba, using hydrochemistry and stable isotope (6(18)O and 6²H) tools. Physical and chemical processes such as diffusion and condensation generate isotopic differentiation in natural waters that can be used to deduce the origins of different waters, and in groundwater the spatial isotopic distribution can be used to deduce hydraulic connections between different aquifers. The Majuba UCG site consists of shallow, intermediate, and saline deep aquifer systems at a depth of 70 m, 180 m, and 300 m respectively. Samples were taken from each aquifer system together with supplementary samples from an on-site water storage dam. The analyses of isotopic compositions led to the determination of the possible sources of each sample. The deep aquifer is represented by an isotopic signature that is depleted in heavy isotopes with average values of -41.7% and -7.02% for 8(18)O and 6²H respectively, while the shallow aquifer is enriched with corresponding average values of -19.9% and -3.3%. Hydrochemical data also showed different water types: a sodium chloride type in the deep aquifer and a sodium bicarbonate water in the shallow aquifer. The results indicate that the shallow aquifer and the deep aquifer are not hydraulically connected, and therefore it is unlikely that groundwater from the gasification zone would contaminate the shallow aquifer.

ABSTRACT: Soil organic matter (SOM), which influences chemical, physical and biological soil attributes, is the main form of C found in the soil which can also be used as a soil sustainability index. The aim of this study was to use the quantity and quality of SOM as an indicator to determine the sustainability of different land uses (native vegetation, secondary vegetation, fruit orchards, horticultural areas, degraded pasture, improved pasture, and fields with annual crops) in the eastern Amazon. Improved pasture had higher soil C stock than the other land uses and was similar to the native vegetation, and also presented the highest quantity of C in a stable form in the soil (fraction < 53 μm). According to the C management index, improved pasture is the most similar in use to native vegetation. Changes in land use reduced the soil microbial C content, although the more conservationist systems (fruit orchards, secondary vegetation, and improved pasture) had contents similar to those of the native vegetation. The highest soil microbial quotients were found in fruit orchards and horticultural areas. Well-managed pastures were effective in accumulating C as stable forms in the soil, which demonstrates the sustainability of this land use in the region studied.

The objective of the study was to evaluate the conversion of a grassland area into a forage and a polycrop area with the application of agroecological methods, through different soil biological, physical and chemical variables, in a farm with animal husbandry-agriculture integration in the Cangrejeras locality Artemisa province, Cuba. The total macrofauna and mesofauna; functional groups of epigeal, anecic and endogeal species of the macrofauna; oribatids, uropodines and gamasines of the mesofauna; underground phytomass; hydrosoluble carbon content; microbial biomass; activity of the dehydrogenase and acid phosphatase enzymes; total organic carbon; percentage of stable aggregates and apparent soil density, were studied. The relation among the variables and their contribution to the grassland conversion were explored by the principal component analysis. From the 16 evaluated variables, only nine (epigeal and endogeal macrofauna, oribatid and uropodine mesofauna, total organic carbon and hydrosoluble carbon, acid phosphatase enzyme, percentage of aggregates and apparent soil density) were recommended for the integral analysis of soil quality and of the impact of the land use change. The integrated analysis of all the variables, according to their correlations and the system arrangement, showed that the conversion from grassland to forage was a favorable agroecological practice for the conservation of soil quality and sustainable soil use; while crop sowing and rotation (polycropping) affected quality.

El estudio tuvo como objetivo evaluar la conversión de un pastizal a un área de forraje y otra de policultivo con la aplicación de métodos agroecológicos, mediante diferentes variables biológicas, físicas y químicas del suelo, en una finca con integración ganadería-agricultura en la localidad de Cangrejeras provincia Artemisa, Cuba. Se estudió la macrofauna y la mesofauna total; los grupos funcionales de epígeos, anécicos y endógeos de la macrofauna; los oribátidos, uropodinos y gamasinos de la mesofauna; la fitomasa subterránea; el contenido de carbono hidrosoluble; la biomasa microbiana; la actividad de las enzimas deshidrogenasa y fosfatasa ácida; el carbono orgánico total; el porcentaje de agregados estables y la densidad aparente del suelo. La relación entre las variables y su contribución a la conversión del pastizal fueron exploradas por el análisis de componentes principales. De las 16 variables evaluadas, solo nueve (macrofauna de epígeos y endógeos, mesofauna de oribátidos y uropodinos, carbono orgánico total y carbono hidrosoluble, enzima fosfatasa ácida, porcentaje de agregados y densidad aparente del suelo) fueron recomendadas para el análisis integral de la calidad del suelo y del impacto del cambio de uso de la tierra. El análisis integrado de todas las variables, de acuerdo a sus correlaciones y al ordenamiento de los sistemas, mostró que la conversión de pastizal a forraje resultó una práctica agroecológica favorable para la conservación de la calidad y el uso sostenible del suelo; mientras que la siembra de cultivos y su rotación (policultivo) afectaron la calidad.

Vários sistemas de interesse físico e biológico podem ser descritos como osciladores auto-sustentados, que mantém seu comportamento oscilatório por meio de um aporte de energia. Do ponto de vista dinâmico, o comportamento de tais sistemas pode ser descrito por meio de um ciclo limite estável no espaço de fase, e o movimento sobre ele é parametrizado por uma fase com uma dada frequência natural. Neste trabalho investigamos o forçamento externo periódico no tempo deste tipo de sistema, destacando os fenômenos de sincronização de frequências, travamento de fase e sincronização generalizada. Um mapa unidimensional é obtido para estender o tratamento matemático geral, que supõe forçamento débil, para o caso de forçamento intenso.

Several systems of physical and biological interest can be described as self-sustained oscillators, which keep their oscillatory behavior using an external energy supply. From the dynamical point of view, the behavior of such systems can be described by means of a stable limit cycle in phase space, on which the motion can be parameterized by a phase with a given natural frequency. In this work we investigate the time-periodic external forcing acting on this kind of system, emphasizing frequency synchronization, phase locking and generalized synchronization. A one-dimensional mapping is obtained in order to extend the general mathematical treatment - which supposes weak forcing - for the case of strong forcing.

Abstract An understanding of wood physical properties and the interrelationships that govern them is required for efficient utilization of timber tree species. Guazuma crinita is a fast-growing timber tree of agroforestry systems in the Peruvian Amazon. The aim of this study was to assess variation in wood physical properties within the G. crinita stem. Wood samples were obtained from the base, middle and top of the stem of 12 randomly selected eight-year-old trees from six provenances in order to determine wood moisture content, density, specific gravity, radial, tangential and volumetric shrinkage and the coefficient of anisotropy. Pearson correlations between physical properties were also determined. The highest basic density was 459 kg/m3 from Tournavista provenance. Mean basic density and specific gravity were 430 kg/m3 and 0.45 respectively. There was statistically significant variation (p ≤ 0.05), due to stem level within the trees. The moderate values of density and anisotropy coefficient (1.56) suggest that G. crinita is a stable wood; these are important advantages in terms of costs of the processes of transport and transformation. Given the variation found in the limited tree samples of this study, we recommend further analysis with larger samples from different provenances and planting zones.

Resumen El entendimiento de las propiedades físicas de la madera y de las interrelaciones que las gobiernan es necesario para el uso eficiente de las especies maderables. Guazuma crinita es una especie arbórea de rápido crecimiento en sistemas agroforestales del Amazonas peruano. El objetivo de este estudio fue determinar la variación de las propiedades físicas de la madera en el fuste de árboles G. crinita. Las muestras de madera fueron obtenidas de la base, parte media y parte superior del tronco de 12 árboles de ocho años de edad aleatoriamente seleccionados, de seis lugares de procedencia. Con ellas se determinó: contenido de humedad, densidad, densidad relativa, contracciones radial, tangencial y volumétrica y coeficiente de anisotropía; se determinaron también las correlaciones de Pearson entre las propiedades físicas. La densidad básica mayor fue 459 kg/m3, de la procedencia de Tournavista. Las densidades básica y relativa promedio fueron 430 kg/m3 y 0.45, respectivamente. Se encontró variación estadísticamente significativa (p ≤ 0.05) entre alturas en el fuste. La madera moderadamente densa y el coeficiente de anisotropía (1.56) sugieren que G. Crinita es una madera estable, lo que representa importantes ventajas en términos de costos por transporte y proceso de transformación. Debido a la variación encontrada en las limitadas muestras de árboles de este estudio, se recomienda la realización de más análisis con mayores muestras y de diferentes sitios y plantaciones.