Rocas volcánicas de las series Inferior y Media del Grupo El Cobre en la Sierra Maestra (Cuba Oriental): volcanismo generado en un arco de islas tholeiítico

Las características geoquímicas (elementos mayores y trazas) de las rocas analizadas son similares a las del arco volcánico de Ke rmadec en Pa c í fico SW. Por último, los bajos contenidos en REE, el patrón de REE con morfología plana, así como los bajos contenidos en elementos incompatibles (K, Rb, Zr, Th) son similares a los de las series tipo IAT presentes en el arco volcánico del Caribe. Estos nuevos datos sobre el volcanismo del Paleógeno de la Sierra Maestra sugieren que los modelos de placas tectónicas que han sido propuestos para explicar el origen del arco volcánico de Sierra Maestra deben ser revisados.

Estudi microtermomètric dels filons de quars de les Esquerdes de Rojà, Massís del Canigó, Pirineu Oriental

Els materials pre-hercinians i el granit de Costabona estan travessats per un conjunt de filons de quars de fins a 15 km de longitud, coneguts com a 'Esquerdes de Roja'. Aquests filons estan localment afectats per un sistema de bandes milonítiques i per un altre posterior de fractures. A partir de l'anilisi microtermometrica de les inclusions fluides primàries en quars, ha estat obtinguda una temperatura de formació de l'ordre de + 280 C per la major part del quars, i una temperatura de + 250 C per als monocristalls que omplen esquerdes i cavitats. Els filons s'haurien format a partir de solucions mineralitzants que contenien ~ a + C, a++, K+ i, en menor proporció, ~ g + + .fins una salinitat total de l'ordre del 20/@ en pes de la Na CI.

Ophiolite-related ultramafic rocks (Serpentinites) in the Caribbean region: a review of their occurrence, composition, origin, emplacements and Ni-Laterite soil formation

Ultramafic rocks, mainly serpentinized peridotites of mantle origin, are mostly associated with the ophiolites of Mesozoic age that occur in belts along three of the margins of the Caribbean plate. The most extensive exposures are in Cuba. The ultramafic-mafic association (ophiolites) were formed and emplaced in several different tectonic environments. Mineralogical studies of the ultramafic rocks and the chemistry of the associated mafic rocks indicate that most of the ultramafic-mafic associations in both the northern and southern margins of the plate were formed in arc-related environments. There is little mantle peridotite exposed in the ophiolitic associations of the west coast of Central America, in the south Caribbean in Curacao and in the Andean belts in Colombia. In these occurrences the chemistry and age of the mafic rocks indicates that this association is mainly part of the 89 Ma Caribbean plateau province. The age of the mantle peridotites and associated ophiolites is probably mainly late Jurassic or Early Cretaceous. Emplacement of the ophiolites possibly began in the Early Cretaceous in Hispaniola and Puerto Rico, but most emplacement took place in the Late Cretaceous to Eocene (e.g. Cuba). Along the northern South America plate margin, in the Caribbean mountain belt, emplacement was by major thrusting and probably was not completed until the Oligocene or even the early Miocene. Caribbean mantle peridotites, before serpentinization, were mainly harzburgites, but dunites and lherzolites are also present. In detail, the mineralogical and chemical composition varies even within one ultramafic body, reflecting melting processes and peridotite/melt interaction in the upper mantle. At least for the northern Caribbean, uplift (postemplacement tectonics) exposed the ultramafic massifs as a land surface to effective laterization in the beginning of the Miocene. Tectonic factors, determining the uplift, exposing the peridotites to weathering varied. In the northern Caribbean, in Guatemala, Jamaica, and Hispaniola, uplift occurred as a result of transpresional movement along pre-existing major faults. In Cuba, uplift occurred on a regional scale, determined by isostatic adjustment. In the south Caribbean, uplift of the Cordillera de la Costa and Serrania del Interior exposing the peridotites, also appears to be related to strike-slip movement along the El Pilar fault system. In the Caribbean, Ni-laterite deposits are currently being mined in the central Dominican Republic, eastern Cuba, northern Venezuela and northwest Colombia. Although apparently formed over ultramafic rocks of similar composition and under similar climatic conditions, the composition of the lateritic soils varies. Factors that probably determined these differences in laterite composition are geomorphology, topography, drainage and tectonics. According to the mineralogy of principal ore-bearing phases, Dominican Ni-laterite deposits are classified as the hydrous silicate-type. The main Ni-bearing minerals are hydrated Mg-Ni silicates (serpentine and ¿garnierite¿) occurring deeper in the profile (saprolite horizon). In contrast, in the deposits of eastern Cuba, the Ni and Cooccurs mainly in the limonite zone composed of Fe hydroxides and oxides as the dominant mineralogy in the upper part of the profile, and are classified as the oxide-type.

Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization

The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis) to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation. C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun.

Risk factors of stroke mortality in the African region: a cohort study

Background: Population-based cohort studies of risk factors of stroke are scarce in developing countries and none has been done in the African region. We conducted a longitudinal study in the Seychelles (Indian Ocean, east of Kenya), a middle-income island state where the majority of the population is of African descent. Such data in Africa are important for international comparison and for advocacy in the region. Methods: Three examination surveys of cardiovascular risk factors were performed in independent samples representative of the general population aged 25-64 in 1989, 1994 and 2004 (n=1081, 1067, and 1255, respectively). Baseline risk factors data were linked with cause-specific mortality from vital statistics up to May 2007 (all deaths are medically certified in the Seychelles and kept in an electronic database). We considered stroke (any type) as a cause of death if the diagnosis was reported in any of the 4 fields in the death certificates for underlying and concomitant causes of death. Results. Among the 2479 persons aged 35-64 at baseline, 280 died including 56 with stroke during follow up (maximum: 18.2 years; mean: 10.2 years). In this age range, age-adjusted mortality rates (/100'000/year) were 969 for all cause and 187 for stroke; age-adjusted prevalence of high blood pressure (≥140/90 mmHg) was 48%. In multivariate Cox survival time regression, stroke mortality was increased by 18% and 35% for a 10-mmHg increase in systolic, respectively diastolic BP (p<0.001). Stroke mortality was also associated with age, smoking ≥5 cigarettes vs. no smoking (HR: 2.4; 95% CI: 1.2-4.8) and diabetes (HR: 1.9; 1.02-3.6) but not with sex, LDL-cholesterol intake, alcohol intake and professional occupation. Conclusion. This first population-based cohort study in the African region demonstrates high mortality rates from stroke in middle-aged adults and confirms associations with high BP and other risk factors. This emphasizes the importance of reducing BP and other modifiable risk factors in high risk individuals and in the general population as a main strategy to reduce the burden of stroke.

Cardiovascular risk factor profiles and their social gradient from adolescence to age 74 in a Swiss region.

BACKGROUND: Few European studies have investigated how cardiovascular risk factors (CRF) in adults relate to those observed in younger generations. OBJECTIVE: To explore this issue in a Swiss region using two population health surveys of 3636 adolescents ages 9-19 years and 3299 adults ages 25-74 years. METHODS: Age patterns of continuous CRF were estimated by robust locally weighted regression and those of high-risk groups were calculated using adult criteria with appropriate adjustment for children. RESULTS: Gender differences in height, weight, blood pressure, and HDL cholesterol observed in adults were found to emerge in adolescents. Overweight, affecting 10-12% of adolescents, was increasing steeply in young adults (three times among males and twice among females) in parallel with inactivity. Median age at smoking initiation was decreasing rapidly from 18 to 20 years in young adults to 15 in adolescents. A statistically significant social gradient in disfavor of the lower education level was observed for overweight in all age groups of women above 16 (odds ratios (ORs) 2.4 to 3.3, P < 0.01), for inactivity in adult males (ORs 1.6 to 2.0, P < 0.05), and for regular smoking in older adolescents (OR 1.9 for males, 2.7 for females, P < 0.005), but not for elevated blood pressure. CONCLUSION: Discontinuities in the cross-sectional age patterns of CRF indicated the emergence of a social gradient and the need for preventive actions against the early adoption of persistent unhealthy behaviors, to which low-educated girls and women are particularly exposed.

Características sedimentológicas de la terminación del ciclo marino del Eoceno superior en el sector oriental de la Depresión del Ebro (Catalunya, N.E. de Espaiia)

Durante el 'Biarritziense' superior y el Priaboniense, la sedimentación en el Eoceno autóctono de Catalunya, adquiere caracteres deltaicos acumulándose los sedimentos en forma de lóbulos deltaicos que translapan sucesivamente y progradan hacia el interior de la cuenca. Cuando los canales distributarios que originan a estos lóbulos son abandonados, se produce un retrabajamiento de sus materiales por la acción marina (oleaje y posiblemente mareas). Es en este episodio cuando, sobre la morfologia dcltaica heredada, se desarrollaron con mucha frecuencia arrecifes de corales y algas rojas que murieron al depositarse sobre ellos los materiales silicoclasticos procedentes de la progradación de un nuevo lóbulo deltacio. Una excepción la constituye el arrecife de Sant Bartomeu del Grau, resultante de la superposición de dos periodos de crecimiento arrecifal, cuya muerte guarda relación, en cada caso, con las primeras etapas de sedimentación evaporitica de la Cuenca evaporitica central catalana. El mecanismo de cierre para este extremo de la cuenca evaporitica se interpreta originado por el estrangulamiento de la misma por la acción de los lóbulos deltaicos procedentes de los bordes Sur y Norte de la cuenca. El estudio cronoestratigráfico efectuado corrobora al modelo paleogeográfico que se expone, el cual, presupone una conexión «mediterránea» por el Emporda durante el Priaboniense.

Ammonia volatilization in no-till system in the south-central region of the State of Paraná, Brazil

Ammonia (NH3) volatilization can reduce the efficiency of urea applied to the surface of no-till (NT) soils. Thus, the objectives of this study were to evaluate the magnitude of NH3 losses from surface-applied urea and to determine if this loss justifies the urea incorporation in soil or its substitution for other N sources under the subtropical climatic conditions of South-Central region of Paraná State, Brazil. The experiment, performed over four harvesting seasons in a clayey Hapludox followed a randomized block design with four replicates. A single dose of N (150 kg ha-1) to V5 growth stage of corn cultivated under NT system was applied and seven treatments were evaluated, including surface-applied urea, ammonium sulfate, ammonium nitrate, urea with urease inhibitor, controlled-release N source, a liquid N source, incorporated urea, and a control treatment with no N application. Ammonia volatilization was evaluated for 20 days after N application using a semi-open static system. The average cumulative NH3 loss due to the superficial application of urea was low (12.5 % of the applied N) compared to the losses observed in warmer regions of Southeastern Brazil (greater than 50 %). The greatest NH3 losses were observed in dry years (up to 25.4 % of the applied N), and losses decreased exponentially as the amount of rainfall after N application increased. Incorporated urea and alternative N sources, with the exception of controlled-release N source, decreased NH3 volatilization in comparison with surface-applied urea. Urea incorporation is advantageous for the reduction of NH3 volatilization; however, other aspects as its low operating efficiency should be considered before this practice is adopted. In the South-Central region of Paraná, the low NH3 losses from the surface-applied urea in NT system due to wet springs and mild temperatures do not justify its replacement for other N sources.

Sintesis litoestratigráfica del Paléogeno del borde oriental de la depresión del Ebro

En esta nota se estudian las unidades litoestratigráficas recictiterriente propuestas para el Paleógeno de la Cordillera Prelitoral Catalana y las correlaciones litológicas a lo largo de la rnistna con referencias de los nombres locales clásicamente eriiplrados.

Temporal variability of soil water content under different surface conditions in the semiarid region of the Pernambuco state

Rainfall in the semiarid region of Pernambuco is characterized by irregular distribution in time and space, which significantly hinders the rainfed agriculture in the region. This work aims to evaluate the temporal profile of soil moisture in the semiarid region of the Pernambuco State (Brazil) and the effect of different soil surface conditions on soil water content variation and the yield of rainfed beans. To monitor soil water content, five plots 4.5 m wide by 11 m long were installed in a Yellow Argisol (Ultisol). The following treatments were adopted in the experimental plots: natural vegetation, bean intercropped with cactus, beans planted down the slope, beans planted along contour lines with mulch and rock barriers, and bare soil. In each plot, eight PVC access tubes were installed for monitoring the soil water content profile at depths of 0.20 and 0.40 m using a neutron probe device. The surface condition significantly influenced the soil water content variation, both in the dry and rainy seasons. The use of mulch, associated with rock barriers, provided higher soil water content levels than the other treatments and increased the rainfed beans production.

Los sistemas lacustres del Eoceno superior y Oligoceno del sector oriental de la Cuenca del Ebro

El relleno sedimentari de edad Priaboniense superior-Chattiense dcl sector oriental de la cuencade antepaís del Ebro puede subdividirse en cinco secuencias deposicionales, definidas en base a 1os principales cambios paleogeográficos que afectaron alos sistemas aluviales y lacustres en la región. Tanto el desarrollo de estructuras tectónicas superficiales como 1os procesos de ajuste isostático regional son considerados como 1os principales factores de control de esta evolución sedimentaria. Los cinco sistemas lacustres reconocidos (La Noguera, L'Anoia, Segarra, L'Urgell y Los Monegros) muestran unas caracteristicas de extensión areal y desarrollo de facies fuertemente controladas por su situación respecto a las zonas de máxima subsidencia. Las tendencias megasecuenciales de cambio o de alternancia de deposición evaporítica y carbonatada, son atribuidas aquí tanto a posibles cambios climáticos como a cambios en la composición del área fuente. Estos fueron inducidos por la evolución tectónica de los margenes de la cuenca.

Diffusion tensor imaging shows structural remodeling of stroke mirror region: results from a pilot study.

Background: The role of the non-injured hemisphere in stroke recovery is poorly understood. In this pilot study, we sought to explore the presence of structural changes detectable by diffusion tensor imaging (DTI) in the contralesional hemispheres of patients who recovered well from ischemic stroke. Methods: We analyzed serial DTI data from 16 stroke patients who had moderate initial neurological deficits (NIHSS scores 3-12) and good functional outcome at 3-6 months (NIHSS score 0 or modified Rankin Score ≤1). We segmented the brain tissue in gray and white matter (GM and WM) and measured the apparent diffusion coefficient (ADC) and fractional anisotropy in the infarct, in the contralesional infarct mirror region as well as in concentrically expanding regions around them. Results: We found that GM and WM ADC significantly increased in the infarct region (p < 0.01) from acute to chronic time points, whereas in the infarct mirror region, GM and WM ADC increased (p < 0.01) and WM fractional anisotropy decreased (p < 0.05). No significant changes were detected in other regions. Conclusion: DTI-based metrics are sensitive to regional structural changes in the contralesional hemisphere during stroke recovery. Prospective studies in larger cohorts with varying levels of recovery are needed to confirm our findings.

Structural changes in latosols of the cerrado region: I - relationships between soil physical properties and least limiting water range

The agricultural potential of Latosols of the Brazilian Cerrado region is high, but when intensively cultivated under inappropriate management systems, the porosity can be seriously reduced, leading to rapid soil degradation. Consequently, accelerated erosion and sedimentation of springs and creeks have been observed. Therefore, the objective of this study was to evaluate structural changes of Latosols in Rio Verde, Goiás, based on the Least Limiting Water Range (LLWR), and relationships between LLWR and other physical properties. Soil samples were collected from the B horizons of five oxidic Latosols representing the textural variability of the Latosols of the Cerrado biome. LLWR and other soil physical properties were determined at various soil compaction degrees induced by uniaxial compression. Soil compaction caused effects varying from enhanced plant growth due to higher water retention, to severe restriction of edaphic functions. Also, inverse relationships were observed between clay content and bulk density values (Bd) under different structural conditions. Bd values corresponding to critical soil macroporosity (BdcMAC) were more restrictive to a sustainable use of the studied Latosols than the critical Bd corresponding to LLWR (BdcLLWR). The high tolerable compression potential of these oxidic Latosols was related to the high aeration porosity associated to the granular structure.

Structural changes in latosols of the cerrado region: II - soil compressive behavior and modeling of additional compaction

Currently in Brazil, as in other parts of the world, the concern is great with the increase of degraded agricultural soil, which is mostly related to the occurrence of soil compaction. Although soil texture is recognized as a very important component in the soil compressive behaviors, there are few studies that quantify its influence on the structural changes of Latosols in the Brazilian Cerrado region. This study aimed to evaluate structural changes and the compressive behavior of Latosols in Rio Verde, Goiás, through the modeling of additional soil compaction. The study was carried out using five Latosols with very different textures, under different soil compaction levels. Water retention and soil compression curves, and bearing capacity models were determined from undisturbed samples collected on the B horizons. Results indicated that clayey and very clayey Latosols were more susceptible to compression than medium-textured soils. Soil compression curves at density values associate with edaphic functions were used to determine the beneficial pressure (σ b) , i.e., pressure with optimal water retention, and critical pressure (σcrMAC), i.e., pressure with macroporosity below critical levels. These pressure values were higher than the preconsolidation pressure (σp), and therefore characterized as additional compaction. Based on the compressive behavior of these Latosols, it can be concluded that the combined preconsolidation pressure, beneficial pressure and critical pressure allow a better understanding of compression processes of Latosols.