999 resultados para work zone
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Numerous measurements by XRD of the Scherrer width at half-peak height (001 reflection of illite), coupled with analyses of clay-size assemblages, provide evidence for strong variations in the conditions of low temperature metamorphism in the Tethyan Himalaya metasediments between the Spiti river and the Tso Morari. Three sectors can be distinguished along the Spiti river-Tso Morari transect. In the SW, the Takling and Parang La area is characterised by a metamorphism around anchizone-epizone boundary conditions. Further north, in the Dutung area, the metamorphic grade abruptly decreases to weak diagenesis, with the presence of mixed-layered clay phases. At the end of the profile towards the NE, a progressive metamorphic increase up to greenschist facies is recorded, marked by the appearance of biotite and chloritoid. The combination of these data with the structural. observations permits to propose that a nappe stack has been crosscut by the younger Dutung-Thaktote extensional fault zone (DTFZ). The change in metamorphism across this zone helps to assess the displacements which occurred during synorogenic extension. In the SW and NE parts of the studied transect, a burial of 12 km has been estimated, assuming a geothermal gradient of 25 degrees C/km. In the SW part, this burial is due to the juxtaposition of the Shikar Beh and Mata nappes and in the NE part, solely to burial beneath the Mata nappe. In the central part of the profile, the effect of the DTFZ is to bring down diagenetic sediments in-between the two aforesaid metamorphic zones. The offset along the Dutung-Thaktote normal faults is estimated at 16 km.
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With the aim of understanding the mechanisms that control the metamorphic transition from the CH4- to the H2O-(CO2)-dominated fluid zone in the Helvetic domain of the Central Alps of Switzerland, fluid inclusions in quartz, illite ``crystallinity'' index, vitrinite reflectance, and the stable isotope compositions of vein and whole rock minerals and fluids trapped in quartz were investigated along four cross-sections. Increasing temperature during prograde metamorphism led to the formation of dry gas by hydrocarbon cracking in the CH4-zone. Fluid immiscibility in the H2O-CH4-(CO2)-NaCl system resulted in cogenetic, CH4- and H2O-dominated fluid inclusions. In the CH4-zone, fluids were trapped at temperatures <= 270 +/- 5 degrees C. The end of the CH4-zone is markedby a sudden increase of CO2 content in the gas phase of fluid inclusions. At temperatures > 270 +/- 5 degrees C, in the H2O-zone, the total amount of volatiles within the fluid decreased below 1 mol% with no immiscibility. This resulted m total homogenization temperatures of H2O-(CO2-CH4)-NaCl inclusions below 180 degrees C. Hydrogen isotope compositions of methane in fluid inclusion have delta D values of less than -100 parts per thousand in the CH4-zone, typical for an origin through cracking of higher hydrocarbons, but where the methane has not equilibrated with the pore water. delta D values of fluid inclusion water are around -40 parts per thousand., in isotopic equilibrium with phyllosilicates of the whole rocks. Within the CH4 to H2O(CO2) transition zone, delta D(H2O) values in fluid inclusions decrease to -130 parts per thousand interpreted to reflect the contribution of deuterium depleted water from methane oxidation. In the H2O-zone, delta D(H2O) values increase again towards an average of -30 parts per thousand which is again consistent with isotopic equilibrium with host-rock phyllosilicates. delta C-13 values of methane in fluid inclusions from the CH4-zone are around -27 parts per thousand in isotopic equilibrium with calcite in veins and whole rocks. The delta C-13(CH4) values decrease to less than -35 parts per thousand at the transition to the H2O-zone and are no longer in equilibrium with the carbonates in the whole rocks. delta C-13 values of CO, are variable but too low to be in equilibrium with the wall rock fluids, compatible with a contribution of CO2 from closed system oxidation of methane. Differences in isotopic composition between host-rock and Alpine fissure carbonate are generally small, suggesting that the amount of CO2 produced by oxidation of methane was small compared to the C-budget in the rocks and local pore fluids were buffered by the wall rocks during precipitation of calcite within the fissures. (c) 2006 Elsevier B.V. All rights reserved.
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The Pesticide Poisoning Surveillance Program within the Division of ADPER & EH monitors, collects, and analyzes pesticide poisonings to determine the extent to which Iowans are being affected by pesticide exposure. The information gathered by this program is disseminated to governmental agencies, the public, and health care professionals. In addition, IDPH is required to submit its findings annually to the Iowa Department of Agriculture and Land Stewardship (IDALS).
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This document is about the different ways Mercury can poison a person and the exposure in Iowa.
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The geologic structures and metamorphic zonation of the northwestern Indian Himalaya contrast significantly with those in the central and eastern parts of the range, where the high-grade metamorphic rocks of the High Himalayan Crystalline (HHC) thrust southward over the weakly metamorphosed sediments of the Lesser Himalaya along the Main Central Thrust (MCT). Indeed, the hanging wall of the MCT in the NW Himalaya mainly consists of the greenschist facies metasediments of the Chamba zone, whereas HHC high-grade rocks are exposed more internally in the range as a large-scale dome called the Gianbul dome. This Gianbul dome is bounded by two oppositely directed shear zones, the NE-dipping Zanskar Shear Zone (ZSZ) on the northern flank and the SW-dipping Miyar Shear Zone (MSZ) on the southern limb. Current models for the emplacement of the HHC in NW India as a dome structure differ mainly in terms of the roles played by both the ZSZ and the MSZ during the tectonothermal evolution of the HHC. In both the channel flow model and wedge extrusion model, the ZSZ acts as a backstop normal fault along which the high-grade metamorphic rocks of the HHC of Zanskar are exhumed. In contrast, the recently proposed tectonic wedging model argues that the ZSZ and the MSZ correspond to one single detachment system that operates as a subhorizontal backthrust off of the MCT. Thus, the kinematic evolution of the two shear zones, the ZSZ and the MSZ, and their structural, metamorphic and chronological relations appear to be diagnostic features for discriminating the different models. In this paper, structural, metamorphic and geochronological data demonstrate that the MSZ and the ZSZ experienced two distinct kinematic evolutions. As such, the data presented in this paper rule out the hypothesis that the MSZ and the ZSZ constitute one single detachment system, as postulated by the tectonic wedging model. Structural, metamorphic and geochronological data are used to present an alternative tectonic model for the large-scale doming in the NW Indian Himalaya involving early NE-directed tectonics, weakness in the upper crust, reduced erosion at the orogenic front and rapid exhumation along both the ZSZ and the MSZ.
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The objective of this work was to evaluate the effect of eucalyptus biochar on the transpiration rate of upland rice 'BRSMG Curinga' as an alternative means to decrease the effect of water stress on plant growth and development. Two-pot experiments were carried out using a completely randomized block design, in a split-plot arrangement, with six replicates. Main plots were water stress (WS) and no-water stress (NWS), and the subplots were biochar doses at 0, 6, 12 and 24% in growing medium (sand). Total transpirable soil water (TTSW), the p factor - defined as the average fraction of TTSW which can be depleted from the root zone before water stress limits growth -, and the normalized transpiration rate (NTR) were determined. Biochar addition increased TTSW and the p factor, and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor) of the growing medium, up to 12% maximum concentration, delaying the point where transpiration declines and affects yield.
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Understanding the emplacement and growth of intrusive bodies in terms of mechanism, duration, ther¬mal evolution and rates are fundamental aspects of crustal evolution. Recent studies show that many plutons grow in several Ma by in situ accretion of discrete magma pulses, which constitute small-scale magmatic reservoirs. The residence time of magmas, and hence their capacities to interact and differentiate, are con¬trolled by the local thermal environment. The latter is highly dependant on 1) the emplacement depth, 2) the magmas and country rock composition, 3) the country rock thermal conductivity, 4) the rate of magma injection and 5) the geometry of the intrusion. In shallow level plutons, where magmas solidify quickly, evi¬dence for magma mixing and/or differentiation processes is considered by many authors to be inherited from deeper levels. This work shows however that in-situ differentiation and magma interactions occurred within basaltic and felsic sills at shallow depth (0.3 GPa) in the St-Jean-du-Doigt (SJDD) bimodal intrusion, France. This intrusion emplaced ca. 347 Ma ago (IDTIMS U/Pb on zircon) in the Precambrian crust of the Armori- can massif and preserves remarkable sill-like emplacement processes of bimodal mafic-felsic magmas. Field evidence coupled to high precision zircon U-Pb dating document progressive thermal maturation within the incrementally built ioppolith. Early m-thick mafic sills (eastern part) form the roof of the intrusion and are homogeneous and fine-grained with planar contacts with neighboring felsic sills; within a minimal 0.8 Ma time span, the system gets warmer (western part). Sills are emplaced by under-accretion under the old east¬ern part, interact and mingle. A striking feature of this younger, warmer part is in-situ differentiation of the mafic sills in the top 40 cm of the layer, which suggests liquids survival in the shallow crust. Rheological and thermal models were performed in order to determine the parameters required to allow this observed in- situ differentiation-accumulation processes. Strong constraints such as total emplacement durations (ca. 0.8 Ma, TIMS date) and pluton thickness (1.5 Km, gravity model) allow a quantitative estimation of the various parameters required (injection rates, incubation time,...). The results show that in-situ differentiation may be achieved in less than 10 years at such shallow depth, provided that: (1) The differentiating sills are injected beneath consolidated, yet still warm basalt sills, which act as low conductive insulating screens (eastern part formation in the SJDD intrusion). The latter are emplaced in a very short time (800 years) at high injection rate (0.5 m/y) in order to create a "hot zone" in the shallow crust (incubation time). This implies that nearly 1/3 of the pluton (400m) is emplaced by a subsequent and sustained magmatic activity occurring on a short time scale at the very beginning of the system. (2) Once incubation time is achieved, the calculations show that a small hot zone is created at the base of the sill pile, where new injections stay above their solidus T°C and may interact and differentiate. Extraction of differentiated residual liquids might eventually take place and mix with newly injected magma as documented in active syn-emplacement shear-zones within the "warm" part of the pluton. (3) Finally, the model show that in order to maintain a permanent hot zone at shallow level, injection rate must be of 0.03 m/y with injection of 5m thick basaltic sills eveiy 130yr, imply¬ing formation of a 15 km thick pluton. As this thickness is in contradiction with the one calculated for SJDD (1.5 Km) and exceed much the average thickness observed for many shallow level plutons, I infer that there is no permanent hot zone (or magma chambers) at such shallow level. I rather propose formation of small, ephemeral (10-15yr) reservoirs, which represent only small portions of the final size of the pluton. Thermal calculations show that, in the case of SJDD, 5m thick basaltic sills emplaced every 1500 y, allow formation of such ephemeral reservoirs. The latter are formed by several sills, which are in a mushy state and may interact and differentiate during a short time.The mineralogical, chemical and isotopic data presented in this study suggest a signature intermediate be¬tween E-MORB- and arc-like for the SJDD mafic sills and feeder dykes. The mantle source involved produced hydrated magmas and may be astenosphere modified by "arc-type" components, probably related to a sub¬ducting slab. Combined fluid mobile/immobile trace elements and Sr-Nd isotopes suggest that such subduc¬tion components are mainly fluids derived from altered oceanic crust with minor effect from the subducted sediments. Close match between the SJDD compositions and BABB may point to a continental back-arc setting with little crustal contamination. If so, the SjDD intrusion is a major witness of an extensional tectonic regime during the Early-Carboniferous, linked to the subduction of the Rheno-Hercynian Ocean beneath the Variscan terranes. Also of interest is the unusual association of cogenetic (same isotopic compositions) K-feldspar A- type granite and albite-granite. A-type granites may form by magma mixing between the mafic magma and crustal melts. Alternatively, they might derive from the melting of a biotite-bearing quartz-feldspathic crustal protolith triggered by early mafic injections at low crustal levels. Albite-granite may form by plagioclase cu¬mulate remelting issued from A-type magma differentiation.
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We analyse the impact of working and contractual conditions, particularly exposure to job risks, on the probability of acquiring a permanent disability, controlling for other personal and firm characteristics. We postulate a model in which this impact is mediated by the choice of occupation, with a level of risk associated with it. We assume this choice is endogenous, and that it depends on preferences and opportunities in the labour market, both of which may differ between immigrants and natives. To test this hypothesis we apply a bivariate probit model to data for 2006 from the Continuous Sample of Working Lives provided by the Spanish Social Security system, containing records for over a million workers. We find that risk exposure increases the probability of permanent disability arising from any cause - by almost 5%.
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The objective of this work was to evaluate sampling density on the prediction accuracy of soil orders, with high spatial resolution, in a viticultural zone of Serra Gaúcha, Southern Brazil. A digital elevation model (DEM), a cartographic base, a conventional soil map, and the Idrisi software were used. Seven predictor variables were calculated and read along with soil classes in randomly distributed points, with sampling densities of 0.5, 1, 1.5, 2, and 4 points per hectare. Data were used to train a decision tree (Gini) and three artificial neural networks: adaptive resonance theory, fuzzy ARTMap; self‑organizing map, SOM; and multi‑layer perceptron, MLP. Estimated maps were compared with the conventional soil map to calculate omission and commission errors, overall accuracy, and quantity and allocation disagreement. The decision tree was less sensitive to sampling density and had the highest accuracy and consistence. The SOM was the less sensitive and most consistent network. The MLP had a critical minimum and showed high inconsistency, whereas fuzzy ARTMap was more sensitive and less accurate. Results indicate that sampling densities used in conventional soil surveys can serve as a reference to predict soil orders in Serra Gaúcha.
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According to Ray Harryhausen, a special effects expert in the film industry, "Gustave Doré would have made a great director of photography . . . He saw things from the point of view of the camera." Doré's work has had a permanent impact on the imaginative realm of film since its very early days. In return, the silver screen has etched Doré into the 20th century imagination. Almost every film about the Bible since The Life and Passion of Jesus Christ produced by Pathé in 1902 refers to his illustrations, and every film adaptation of Dante or Don Quixote has used him as a model, from Georg Wilhelm Pabst and Orson Welles to Terry Gilliam. All films dealing with life in London in the Victorian era by directors ranging from David Lean, to Roman Polanski and Tim Burton draw on the visions in London: a pilgrimage for their sets. A large number of dream fantastical or phantasmagorical scenes take their inspiration from Doré's graphic world, beginning with Georges Méliès' A Trip to the Moon in 1902. In the realm of cartoons and animation, Walt Disney owes a huge debt to Doré. Doré primal forests, from Atala in particular, were also used in the various versions of King Kong from 1933 to the 2005 film by Peter Jackson, who had already drawn on Doré for The Lord of the Rings. Jean Cocteau was also indebted to the illustrations for Perrault's Fairy Tales for his Beauty and the Beast (1945), as was George Lucas for the character Chewbacca in Star Wars (1977) and even the Harry Potter film series. Through his influence on film history, Doré shaped the mass culture imagination.