1,965 research outputs found

    Mapa pedológico como auxílio para o uso de terras para construção civil em planície costeira.

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    Nas últimas décadas a pressão imobiliária nas áreas litorânea e próximas às praias revela-se um problema no Brasil. São inúmeros os casos de degradação ambiental em áreas litorâneas oriundas da expansão imobiliária sem planejamento e sem estudos de impactos ambientais e geotécnicos. Os resultados desta pesquisa mostram que mapas pedológicos são de grande valia como material auxiliar à classificação de terras para a construção civil, levando-se em consideração aspectos geotécnicos e ambientais

    Contenido de Cadmio y Plomo en tejido de Hígado y Riñón en el Jote de Cabeza Colorada Cathartes aura (Linneo, 1758) de Chañaral, Desierto de Atacama, Chile

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    Indexación: Web of Science; ScieloThe Atacama region, Chile, presents one of the highest levels of mining exploitation of the country, which leads to high levels of contamination from mine tailings and other related environmental liabilities. One of the most complex situations occurred in the Chañaral city, north of Chile, where for over 50 years mine tailings were dumped on the coast, causing severe damage in the ecosystem. To evaluate the effects on terrestrial biota, we analyzed the concentration of cadmium and lead in tissues of Turkey Vulture (Cathartes aura). The results indicate that accumulation of cadmium in kidney was 10.31 μg/g (SD 8.00, range 0.27 to 20.73 μg/g) while in the liver was 5.24 μg/g (SD 8.00, range 0.49 to 19.70). There values are very high when compared to data for other birds with similar ecological role. In relation to the lead, concentration in liver was 0.86 μg/g (SD 2.03, range 0.15 - 7.90), while in kidney was 1.05 μg/g (DS 2.54, range 0.044 to 9.86), values considered within the normal range. It is interesting to analyze from the perspective of the availability of these metals in the mining tailings, where lead (1.57 to 21.2 μg/g) presented higher levels than cadmium (0.061 to 1.085 μg/g). The difference between organs may be related to the role of metallothionein. We discuss the role of Turkey Vulture as a bioindicator of environmental liabilities.La Región de Atacama, Chile, presenta uno de los mayores niveles de explotación minera del país, el cual a su vez genera altos niveles de contaminación por relaves mineros y otros pasivos ambientales relacionados. Una de las más complejas situaciones ocurrió en la ciudad de Chañaral, norte de Chile, donde fueron liberados relaves mineros a sus costas por sobre 50 años, causando graves daños en el ecosistema. Para evaluar los efectos en la biota terrestre, nosotros analizamos la concentración de Cadmio y Plomo en tejidos del Jote de Cabeza Colorada (Cathartes aura). Los resultados indican que la acumulación de Cadmio en el Riñón fue 10,31 μg/g (DS 8,00, rango 0,27 a 20,73 μg/g) mientras en el Hígado fue 5,24 μg/g (DS 8,00, rango 0,49 a 19,70). Estos valores son muy altos si se compara con datos de otras aves de similar rol ecológico. En relación al Plomo, la concentración en Hígado fue de 0,86 μg/g (DS 2,03, rango 0,15 a 7,90), mientras que en Riñón fue de 1,05 μg/g (DS 2,54, rango 0,044 a 9,86), valores considerados dentro del rango normal. Estos resultados son interesantes de analizar desde la perspectiva de la disponibilidad de estos metales en el relave minero, donde el Plomo (1,57 a 21,2 μg/g) presentó mayores niveles que el Cadmio (0,061 a 1,085 μg/g). La diferencia entre órganos puede ser relacionado al rol de las metalotioneinas. Discutimos el rol del Jote de Cabeza Colorada como bioindicador de contaminaciones ambientales.http://ref.scielo.org/86hcb

    Simulation of Suspensions, Torsion Bars, and Fifth Wheel for Semitrailers Using Finite Elements

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    The objective of this paper is the simulation of some different types of elements for semitrailers, like the suspension, both mechanical with springs and pneumatic with a spring anddiapresses; other parts like the wheels, the torsion bars, the fifth wheel and the suspension of the tractor unit have also been simulated. Then, the numerical simplified FE model of these elements that allows simulating the real behavior of the suspension to apply adequately the boundary conditions of a heavy vehicle has been obtained for a structural simulation using numerical tools with a good accuracy of the local and global behavior of the vehicle

    Convergence in light capture efficiencies among tropical forest understory plants with contrasting crown architectures: a case of morphological compensation

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    10 páginas, 5 figuras y 4 tablasLeaf and crown characteristics were examined for 24 tree and herbaceous species of contrasting architectures from the understory of a lowland rainforest. Light-capture efficiency was estimated for the crowns of the different species with a three-dimensional geometric modeling program. Causal relationships among traits affecting light absorption at two hierarchical levels (leaf and whole crown) were quantified using path analysis. Light-capture and foliage display efficiency were found to be very similar among the 24 species studied, with most converging on a narrow range of light absorption efficiencies (ratio of absorbed vs. available light of 0.60– 0.75). Exceptionally low values were found for the climber vines and, to a lesser extent, for the Bromeliad Aechmea magdalenae. Differences in photosynthetic photon flux density (PFD) absorbed per unit leaf area by individual plants were mostly determined by site to site variation in PFD and not by the differences in crown architecture among individuals or species. Leaf angle, and to a lesser extent also supporting biomass, specific leaf area, and internode length, had a significant effect on foliage display efficiency. Potential constraints on light capture such as the phyllotactic pattern were generally offset by other compensatory adjustments of crown structure such as internode length, arching stems, and plagiotropy. The variety of shoot morphologies capable of efficiently capturing light in tropical forest understories is greater than initially thought, extending over species with very different phyllotactic patterns, crown architectures, leaf sizes, and morphologies.This research was supported by Mellon foundation/ Smithsonian Institution fellowships to FV and RWP, NSF Grant IBN 96-04424. Manuscript preparation was supported by a train and mobility grant given to FV by the Spanish Ministry of Education, Culture and Sports and a Professional Development Grant to JBS from the California State University.The authors thank Eduardo Sierra for help with the identification of the individuals studied, to Eloisa Lasso for help with data collection, and to Lourens Poorter for fitting criticisms. This research was supported by Mellon foundation/ Smithsonian Institution fellowships to FV and RWP, NSF Grant IBN 96-04424.Peer reviewe

    Spatial variability of soil physical attributes in Machadinho d Oeste (Ro), Amazon Basin.

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    The aim of this paper was to understand the spatial variability of soil physical attributes within the superficial layer (0-10 cm) in an area of agricultural colonization in Machadinho d?Oeste (RO). The attributes analyzed were real density, clay, silt, coarse sand, and fine sand contents. In September, 2004, 76 samples were collected through an irregular sampling strategy, based on soil and topographic features. Oxisols and Ultisols are the predominant soil types in the area. The clay content ranged from 2 to 67%, silt from 2 to 63%, coarse sand from 4 to 78%, fine sand from 6 to 45%, and real density from 2.08 to 2.60 (g cm-3). Some of the high contents of silt can be due to resistant aggregates of the clay fraction, as the adopted methodology did not separate clay grains. The majority of attributes presented coefficients of variation higher than 40%, except for real density. Real density is highly correlated with the coarse sand fraction (r = 0,94) and with the sum of the clay and silt fractions (r = -0,86). Geostatistics was used to understand the spatial variability of such attributes, through the analysis of semivariograms, kriging, and isoline maps. Despite statistical distances among the samples, the spatial dependence ratio (RD) was classified as moderate and strong. The spherical model had good adjustment for the studied attributes. Similarities were found for the spatial behavior of some attributes, such as clay, coarse sand, and real density. The lowest range values were for clay, silt, and coarse sand (i.e., around 10,000 m). For fine sand and real density, the range was between 15,000 and 16,000 m. Kriging techniques were suitable to depict the space distribution of the studied attributes. Soils with clay contents higher than 30% are predominant in the area, followed by soils with loam texture

    Comparative assessment of biologics in treatment of psoriasis: drug design and clinical effectiveness of ustekinumab

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    The development of psoriasis and psoriatic arthritis is a multistep process that leads to chronic or recurrent inflammation. Recent studies have suggested the importance of T helper (TH)1 and TH17 cells, accessory cells, and proinflammatory cytokines in the pathogenesis of the enthesis, synovium, and skin involvement in psoriasis in the presence of susceptibility genes that remain quiescent until triggered. Biologics, such as soluble CTLA-4 immunoglobulin, tumor necrosis factor (TNF) inhibitors, and ustekinumab, inhibit T cell activation which eventually leads to further stimulation of the interleukin 12, 17, and 23 axis, TNF-α, and lymphotoxin-α. Treatment with TNF-α blockers has been effective in refractory psoriasis and psoriatic arthritis, but there is still a subgroup of patients who do not respond to TNF inhibitors and, paradoxically, when treated, may develop TNF-induced psoriasis. Ustekinumab, because of its different mechanism of action at the level of the interleukin 12, 17, and 23 pathways, is an alternative treatment for this group of patients

    C/NOFS Satellite Electric Field and Plasma Density Observations of Plasma Instabilities Below the Equatorial F-Peak -- Evidence for Approximately 500 km-Scale Spread-F "Precursor" Waves Driven by Zonal Shear Flow and km-Scale, Narrow-Banded Irregularities

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    As solar activity has increased, the ionosphere F-peak has been elevated on numerous occasions above the C/NOFS satellite perigee of 400km. In particular, during the month of April, 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set (to our knowledge): The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second new result (for C/NOFS) is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is below the F -peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field component of these waves is strongest in the zonal direction. These waves are strongly correlated with simultaneous observations of plasma density oscillations and appear both with, and without, evidence of larger-scale spread-F depletions. These km-scale, quasi-coherent waves strongly resemble the bottomside, sinusoidal irregularities reported in the Atmosphere Explorer satellite data set by Valladares et al. [JGR, 88, 8025, 1983]. We interpret these new observations in terms of fundamental plasma instabilities associated with the unstable, nighttime equatorial ionosphere
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