814 resultados para Tectonic settings
Resumo:
Despite the popularity of youth sport programs, little research has examined the psychosocial benefits assumed to stem from involvement. Some studies suggest birthplace influences the development of elite athletes, but little work has examined other influences of community contexts. The purpose of this study was to examine relationships between young athletes’ community size, developmental assets, and sport involvement. Current and recently withdrawn competitive swimmers (N = 181) completed the Developmental Assets Profile (Search Institute, 2004). Athletes from smaller cities had significantly higher developmental asset scores for support, commitment to learning, and boundaries/expectations. Further, community size was a significant predictor of withdrawal. Findings suggest community context should be given additional attention in youth sport literature.
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The purpose of the current dissertation is to identify the features of effective interventions by exploring the experiences of youth with ASD who participate in such interventions, through two intervention studies (Studies 1 and 2) and one interview study (Study 3). Studies 1 and 2 were designed to support the development of social competence of youth with ASD through Structured Play with LEGO TM (Study 1, 12 youths with ASD, ages 7–12) and Minecraft TM (Study 2, 4 youths with ASD, ages 11–13). Over the course of the sessions, the play of the youth developed from parallel play (children playing alone, without interacting) to co-operative play (playing together with shared objectives). The results of Study 2 showed that rates of initiations and levels of engagement increased from the first session to the final session. In Study 3, 12 youths with ASD (ages 10–14) and at least one of their parents were interviewed to explore what children and their parents want from programs designed to improve social competence, which activities and practices were perceived to promote social competence by the participants, and which factors affected their decisions regarding these programs. The adolescents and parents looked for programs that supported social development and emotional wellbeing, but did not always have access to the programs they would have preferred, with factors such as cost and location reducing their options. Three overarching themes emerged through analysis of the three studies: (a) interests of the youth; (b) structure, both through interactions and instruction; and (c) naturalistic settings. Adolescents generally engage more willingly in interventions that incorporate their interests, such as play with Minecraft TM in Study 2. Additionally, Structured Play and structured instruction were crucial components of providing safe and supportive contexts for the development of social competence. Finally, skills learned in naturalistic settings tend to be applied more successfully in everyday situations. The themes are analysed through the lens of Vygotsky’s (1978) perspectives on learning, play, and development. Implications of the results for practitioners and researchers are discussed.
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The anisotropy of magnetic susceptibility (AMS) has been measured with low- and high-field methods, in deformed carbonate rocks along the Morcles nappe shear zone (Helvetic Alps). High-field measurements at room temperature and 77 K enable the separation of the ferrimagnetic, paramagnetic and diamagnetic anisotropy. The ferrimagnetic sub-fabric is generally insignificant in these rocks, contributing less than 10% to the total AMS. AMS results for both the separated diamagnetic and paramagnetic subfabrics are consistent with the regional shear movement in the late-stage formation of the Helvetic nappes, as seen in the Morcles nappe, whose inverted limb indicate shear displacement towards the northwest. The diamagnetic anisotropy correlates well quantitatively with the calculated magnetic anisotropy based on the calcite texture. There is a gradational change in the degree of anisotropy related to the strain gradient along the shear zone. A more complex magnetic fabric, resulting from partial overprinting due to displacement along the Simplon–Rhône fault, is evident at one site near the root zone of the nappe. Partial overprinting of the magnetic fabric appears to have taken place in two locations farther up the shear zone as well. This late phase deformation is associated with recent exhumation of the Mont Blanc and Belledonne external massifs and orogen parallel extension, and is reflected by the AMS. Rocks with bulk susceptibility ∼0 SI, and simple mineral compositions are ideal for low temperature high-field torque, as this method helps to enhance the paramagnetic susceptibility and anisotropy, which may otherwise be masked by the mixed magnetic contributions of the composite magnetic fabric.
Resumo:
The major geologic units of the Itremo region in central Madagascar include: (1) upper amphibolite to granulite facies (higher grade) Precambrian rocks, mainly para- and orthogneisses, and migmatites; (2) the newly defined Itremo Nappes, a fold-and-thrust belt containing the Proterozoic Itremo Group sediments, metamorphosed at greenschist to lower amphibolite facies (lower grade) conditions: (3) Middle Neoproterozoic and Late Neoproterozoic-Cambrian intrusives. The stratigraphic succession of the Itremo Group in the eastern part of the Itremo region is, from bottom to top: quartzites, metapelites, metacarbonates and metapelites overlain by metacarbonates. During D1 the Itremo Group sediments were detached from their continental substratum, deformed into a fold-and-thrust nappe (Itremo Nappes), and transported on top of higher grade rocks that are intruded by Middle Neoproterozoic (c. 797–780 Ma) granites and gabbros. A second phase of deformation shortening (D2) affected both the Itremo Sedimentary Nappes and structurally underlying higher-grade rocksunits, and formed large-scale N-S-trending F2 folds. S1 axial plane foliations in Itremo Group sediments are truncated by Late Neoproterozoic-Cambrian granites (c. 570–540 Ma). The age of the formation of the Itremo Nappes is not well constrained: they formed in Neoproterozoic times between 780 and 570 Ma.
Resumo:
The Itremo region in Central Madagascar comprises a deformed metasedimentary sequence (Itremo Group) that has undergone greenschist to lower amphibolite facies metamorphism. During a first phase of deformation (D1) Itremo Group sediments were deformed into a fold-and-thrust belt and transported toward the E to NE on top of migmatitic gneisses rocks of Anatananarivo block. A second phase of deformation (D2) affected both the fold-and-thrust belt and structurally underlying units, and formed large-scale N-S trending folds with steeply dipping axial planes. A Late Neoproterozoic Th–U–Pb XRF monazite age (565±17 Ma) dates the emplacement of a granite that truncates first-phase structures in the Itremo Group, and indicates that the fold-and-thrust belt formed prior to ≈565 Ma. Th–U–Pb electron microprobe dating was applied to elongated monazites that lie within the first-phase foliation of Itremo Group metapelites. The detrital cores of zoned monazites reveal two distinct age populations at ∼2000 and 1700 Ma, the latter age giving a maximum depositional age for the Itremo Group. Statistical analysis of ages determined from the rims of zoned monazites and from unzoned monazites indicates three Late Proterozoic–Early Paleozoic monazite growth events at about 565–540, 500 and 430 Ma. The oldest age population is contemporaneous within error, with the intrusion of the dated granite. The two younger age populations are found both in the Th–U–Pb and Ar–Ar data; together with the perturbation of the Rb–Sr system we interpret both ages as due to alteration related to fluid circulation events, possibly connected to the emplacement of pegmatite fields in Central Madagascar. Syn-D1 tectonic growth of contact metamorphism minerals such as andalusite has been observed locally in metapelites along the margin of Middle Neoproterozoic (≈800 Ma) granites, suggesting that D1 in the Itremo Group is contemporaneous with the intrusion of granites at ≈800 Ma. The N-S trending D2 folds are associated with ≈E-W shortening during the final assembly of Gondwana in Late Neoproterozoic–Early Cambrian times.
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BACKGROUND The Kato-Katz technique is recommended for the diagnosis of helminth infections in epidemiological surveys, drug efficacy studies and monitoring of control interventions. We assessed the comparability of the average amount of faeces generated by three Kato-Katz templates included in test kits from two different providers. METHODS Nine hundred Kato-Katz thick smear preparations were done; 300 per kit. Empty slides, slides plus Kato-Katz template filled with stool and slides plus stool after careful removal of the template were weighed to the nearest 0.1 mg. The average amount of stool that was generated on the slide was calculated for each template, stratified by standard categories of stool consistency (i.e. mushy, soft, sausage-shaped, hard and clumpy). RESULTS The average amount of stool generated on slides was 40.7 mg (95 % confidence interval (CI): 40.0-41.4 mg), 40.3 mg (95 % CI: 39.7-40.9 mg) and 42.8 mg (95 % CI: 42.2-43.3 mg) for the standard Vestergaard Frandsen template, and two different templates from the Chinese Center for Disease Control and Prevention (China CDC), respectively. Mushy stool resulted in considerably lower average weights when the Vestergaard Frandsen (37.0 mg; 95 % CI: 34.9-39.0 mg) or new China CDC templates (37.4 mg; 95 % CI: 35.9-38.9 mg) were used, compared to the old China CDC template (42.2 mg; 95 % CI: 40.7-43.7 mg) and compared to other stool consistency categories. CONCLUSION The average amount of stool generated by three specific Kato-Katz templates was similar (40.3-42.8 mg). Since the multiplication factor is somewhat arbitrary and small changes only have little effect on infection intensity categories, it is suggested that the standard multiplication factor of 24 should be kept for the calculation of eggs per gram of faeces for all investigated templates.
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Bulk sediment accumulation rates and carbonate and carbonate-free accumulation rates corrected for tectonic tilting have been calculated for Leg 78A sediments. These rates are uniformly low, ranging from 0.1 to 6.8 g/(cm**2 x 10**3 yr.), reflecting the pelagic-hemipelagic nature of all the sediments drilled in the northern Lesser Antilles forearc. Rates calculated for Sites 541 and 542 [0.6-6.8 g/(cm**2 x 10**3 yr.)], located on the lower slope of the accretionary prism, are significantly greater than the Neogene rates calculated for oceanic reference Site 543 [0.1-2.4 g/(cm**2 x 10**3)]. This difference could be the result of (1) tectonic thickening of accretionary prism sediments due to folding, small-scale faulting, and layer-parallel shortening; (2) deposition in shallower water farther above the CCD (carbonate compensation depth) resulting in preservation of a greater percentage of calcareous microfossils; or (3) a greater percentage of foraminiferal sediment gravity flows. Terrigenous turbidites are not documented in the Leg 78A area because of (1) great distance from South American sources; (2) damming effects of east-west trending tectonic elements; and (3) location on the Tiburon Rise (Site 543). This lack of terrigenous material, characteristic of intraoceanic convergent margins, suggests that published sedimentation models for active continental convergent margins with abundant terrigenous influxes are not applicable to intraoceanic convergent margin settings.
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Cape Roberts Project drillcore 1 was obtained from Roberts Ridge, a sea-floor high located at 77°S, 16 km offshore from Cape Roberts in western McMurdo Sound, Antarctica. The recovered core is about 147 m long with the upper 43.15 metres below the sea floor (revised figure) being dated as Quarternary and the older part of the sequence being Miocene. The core includes nine facies: sandy diamict, muddy diamict, gravel/conglomerate, mud(stone), clay(stone) and carbonate. These facies occure in associations that are repeated in particulare sequences throughout the core, and are interpreted as representing different depositional environments through time. Seven lithofacies associations are interpreted as representing offshore shelf, ice protected/below wave-base; prodeltaic/offshore shelf; delta front/sandy shelf; ice system; subglacial till/rainout diamict/debris flow diamicts singly or in combination; and a carbonate-rich shelf bank. The facies associations are used to infer that the Quaternary section represents deposition on a polar shelf with perhaps two or three glacial fluctuations. The Quaternary carbonate unit indicates a period of ice sheet retreat, but local glacial activity may have increased with an increase in costal precipitation. The Miocene section represents polythermal glacial systems. The older Miocene section is glacially dominated whereas the younger section is much less so. The glacially dominated section may provide evidence for a major glacial advance thar resulted un a low stand of global eustatic sea level at that time. After the low stand, eustatic sea level was gradually rising during deposition of the younger section dominated more by non-glacial processes.
Resumo:
The Cretaceous Equatorial Atlantic Gateway between the Central and South Atlantic basins is of interest not only for paleoceanographic and paleoclimatic studies, but also because it provided particularly favourable conditions for the accumulation and preservation of organic-rich sediments. Deposition of carbonaceous sediments along the Côte d'Ivoire-Ghana Transform Margin (Ocean Drilling Program Leg 159) was intimately linked to the plate tectonic and paleoceanographic evolution of this gateway. Notably, the formation of a marginal basement ridge on the southeastern border of the transform margin provided an efficient shelter of the landward Deep Ivorian Basin against erosive and potentially oxidizing currents. Different subsidence histories across the transform margin were responsible for the development of distinct depositional settings on the crest and on both sides of the basement ridge. Whereas the southern, oceanward flank of the basement ridge was characterized by rapid, continuous deepening since last Albian-early Cenomanian, marine sedimentation on the northern, landward flank was interrupted by a period of uplift and erosion in the late Albian, and rapid subsidence started after the early Coniacian. Organic-rich sediments occur throughout almost the entire Cretaceous section, but hydrogen-rich marine black shales were exclusively recovered from core sections above an uplift-related unconformity. These black shales formed when separation of Africa and South America was sufficient to allow permanent oceanic midwater exchange after the late Albian. Four periods of black shale accumulation are recovered, some of them are correlated with the global oceanic anoxic events: in the last Albian-earliest Cenomanian, at the Cenomanian-Turronian boundary, during the middle Coniacian-early Campanian, and in the mid-Maastrichtian. These periods were characterized by increasing carbon flux to the seafloor, induced by enhanced palaeoproductivity and intensified supply of terrestrial organic matter. Black shale depostion appears to be intimately linked to periods of rising or maximum eustatic sea level and to the expansion of the oxygen minimum zone, as indicated by foraminiferal biofacies. Intervals between black shales units, in contrast, indicate a shrinking oxygen minimum zone and enhanced detrital flux rates, probably related to lowering sea level. Upper Cretaceous detritral limestones with high porosities may provide excellent hydrocarbon reservoirs, alsthough their areal extent appears to be limited. Palaeogene porcellanites, capped by Neogene pelagic marls and clays, extend over a wider area and max provide another target for hydrocarbon exploration.
Resumo:
PURPOSE To evaluate image contrast and color setting on assessment of retinal structures and morphology in spectral-domain optical coherence tomography. METHODS Two hundred and forty-eight Spectralis spectral-domain optical coherence tomography B-scans of 62 patients were analyzed by 4 readers. B-scans were extracted in 4 settings: W + N = white background with black image at normal contrast 9; W + H = white background with black image at maximum contrast 16; B + N = black background with white image at normal contrast 12; B + H = black background with white image at maximum contrast 16. Readers analyzed the images to identify morphologic features. Interreader correlation was calculated. Differences between Fleiss-kappa correlation coefficients were examined using bootstrap method. Any setting with significantly higher correlation coefficient was deemed superior for evaluating specific features. RESULTS Correlation coefficients differed among settings. No single setting was superior for all respective spectral-domain optical coherence tomography parameters (P = 0.3773). Some variables showed no differences among settings. Hard exudates and subretinal fluid were best seen with B + H (κ = 0.46, P = 0.0237 and κ = 0.78, P = 0.002). Microaneurysms were best seen with W + N (κ = 0.56, P = 0.025). Vitreomacular interface, enhanced transmission signal, and epiretinal membrane were best identified using all color/contrast settings together (κ = 0.44, P = 0.042, κ = 0.57, P = 0.01, and κ = 0.62, P ≤ 0.0001). CONCLUSION Contrast and background affect the evaluation of retinal structures on spectral-domain optical coherence tomography images. No single setting was superior for all features, though certain changes were best seen with specific settings.