Denudation history of the Bocaina Plateau, Serra do Mar, southeastern Brazil: Relationships to Gondwana breakup and passive margin development

The Bocaina Plateau, which is situated on the eastern flank of the continental rift of southeastern Brazil, is the highest part of the Serra do Mar. Topographic relief in this area is suggested to be closely related to its complex tectono-magmatic evolution since the breakup of Western Gondwana and opening of the South Atlantic Ocean. Apatite fission track ages and track length distributions from 27 basement outcrops were determined to assess these hypotheses and reconstruct the denudation history of the Bocaina Plateau. The ages range between 303 +/- 32 and 46 +/- 5 Ma, and are significantly younger than the stratigraphic ages. Mean track lengths vary from 13.44 +/- 1.51 to 11.1 +/- 1.48 mu m, with standard deviations between 1.16 and 1.83 mu m. Contrasting ages within a single plateau and similar ages at different altitudes indicate a complex regional tectonothermal evolution. The thermal histories inferred from these data imply three periods of accelerated cooling related to the Early Cretaceous continental breakup, Early Cretaceous alkaline magmatism, and the Paleogene evolution of the continental rift of southeastern Brazil. The oldest fission track ages (>200 Ma) were obtained in the Serra do Mar region, suggesting that these areas were a long-lived source of sediments for the Parana, Bauru, and Santos basins. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Nd and Pb isotope signatures on the Southeastern South American upper margin: Implications for sediment transport and source rocks

Neodymium and lead isotope values in sediment samples were used to interpret sediment transport and source rocks on the Southeastern South American upper margin. The sediments of the Argentinian margin exhibit an average epsilon(Nd) value of -1.9, indicating the influence of the Andean rocks as sediment sources. Sediments from the Rio de La Plata estuary show an average epsilon(Nd) value of -9.6 which is similar to that of the Southern Brazilian Upper Margin. Finally, sediments of Southeastern Brazil, which are associated with the transport of the Brazil Current exhibit an average epsilon(Nd) of -13.0. The Pb isotope signatures also confirm the differentiation of source rocks in the sedimentation of the study area. In addition, Pb isotopes helped to establish the extent of the influence of the Rio de La Plata on the sedimentation of the Southern Brazilian margin. In terms of Pb isotopes the sediments from the Rio de La Plata estuary and Southern Brazil are more radiogenic than those of Southeastem Brazil and the Argentinian margin. (c) 2007 Elsevier B.V. All rights reserved.

Quaternary tectonics in a passive margin: Marajo Island, northern Brazil

Marajo Island is located in a passive continental margin that evolved from rifting associated with the opening of the Equatorial South Atlantic Ocean in the Late Jurassic/Early Cretaceous period. This study, based on remote sensing integrated with sedimentology, as well as subsurface and seismographic data available from the literature, allows discussion of the significance of tectonics during the Quaternary history of marginal basins. Results show that eastern Marajo Island contains channels with evidence of tectonic control. Mapping of straight channels defined four main groups of lineaments (i.e. NNE-SSW, NE-SW, NW-SE and E-W) that parallel main normal and strike-slip fault zones recorded for the Amazon region. Additionally, sedimentological studies of late Quaternary and Holocene deposits indicate numerous ductile and brittle structures within stratigraphic horizons bounded by undeformed strata, related to seismogenic deformation during or shortly after sediment deposition. This conclusion is consistent with subsurface Bouguer mapping suggestive of eastern Marajo Island being still part of the Marajo graben system, where important fault reactivation is recorded up to the Quaternary. Together with the recognition of several phases of fault reactivation, these data suggest that faults developed in association with rift basins might remain active in passive margins, imposing important control on development of depositional systems. Copyright (C) 2007 John Wiley & Sons, Ltd.

Lower bounds for stability margin of n-dimensional discrete systems

This paper derives lower bounds for the stability margin of n-dimensional discrete systems in the Roesser’s state space setting. The lower bounds for stability margin are derived based on the MacLaurine series expansion. Numerical examples are given to illustrate the results.

The trading dynamics of close-substitute futures markets : evidence of margin policy spillover effects

Volatility spillover is well documented among closely related securities. I investigate the relationship between margin policy and trading dynamics of the Nikkei 225 index futures markets of Osaka Securities Exchange (OSE) and Singapore Exchange (SGX). I find that OSE’s margin policy influences trading dynamics across both markets, although it is the less liquid SGX market that performs price discovery. This suggests that policy markers of close substitute markets should coordinate, or at least communicate policy intentions due to policy spillover. SGX’s market design facilitates price discovery, suggesting that a microstructure framework capable of overcoming the liquidity entry barrier is of interest to any futures exchange contemplating contract proliferation.

Teachers' work and professional identity: living a contradiction on the margin

Currently in Victoria, the Government is spending millions of dollars on the implementation of literacy intervention programs in State Schools. This narrative explores an English teacher's experiences as she implemented a literacy intervention program at her school, where she was confronted by questions about its value, nature and purpose, as well as challenges to her professional identity.

Invertebrate diversity of the unexplored marine western margin of Australia: taxonomy and implications for global biodiversity

However derived, predictions of global marine species diversity rely on existing real data. All methods, whether based on past rates of species descriptions, on expert opinion, on the fraction of undescribed species in samples collected, or on ratios between taxa in the taxonomic hierarchy, suffer the same limitation. Here we show that infaunal macrofauna (crustaceans and polychaetes) of the lower bathyal depth range are underrepresented among available data and documented results from Australia. The crustacean and polychaete fauna (only partially identified) of the bathyal continental margin of Western Australia comprised 805 species, representing a largely novel and endemic fauna. Overall, 94.6% of crustacean species were undescribed, while 72% of polychaete species were new to the Australian fauna, including all tanaidaceans, amphipods, and cumaceans, as well as most isopods. Most species were rare, and the species accumulation rate showed no sign of reaching an asymptote with increasing area sampled. Similar data are likely for the largely unexplored bathyal regions. This leads us to conclude that the numbers upon which extrapolations to larger areas are based are too low to provide confidence. The Southern Australian and Indo-West Pacific deep-sea regions contribute significantly to global species diversity. These regions and bathyal and abyssal habitats generally are extensive, but are so-far poorly sampled. They appear to be dominated by taxonomically poorly worked and species-rich taxa with limited distributions. The combination of high species richness among infaunal taxa-compared to better known taxa with larger individuals, higher endemism than presently acknowledged because of the presence of cryptic species, the low proportion of described species in these taxa, and the vast extent of unexplored bathyal and abyssal environments-will lead to further accumulation of new species as more and more deep sea regions are explored. It remains to be tested whether ratios of 10 or more undescribed to described species, found in this study for the dominant taxa and for the deep Southern Ocean and the Indo-West Pacific, are replicable in other areas. Our data and similar figures from other remote regions, and the lack of faunal overlap, suggest that Appeltans et al.'s (Current Biology 22:1-14, 2012) estimate that between one-third and two-thirds of the world's marine fauna is undescribed is low, and that Mora et al.'s (PLoS Biol 9(8):e1001127. doi:10.1371/journal.pbio.1001127, 2011) of 91% is more probable. We conclude that estimates of global species, however made, are based on limited data. © 2014 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg.

Benefits of education at the intensive margin: childhood academic performance and adult outcomes among American immigrants

Using the Children of the Immigrants Longitudinal Study (CILS), we examine the associationbetween education at the intensive margin and twenty pecuniary and non-pecuniary adultoutcomes among first- and second-generation American immigrant youth. Education at theintensive margin is measured by two widely used standardized math and reading test scores,national percentile rankings on these tests and cumulative grade point average (GPA) in bothmiddle and high school. Our findings provide evidence that the academic achievement ofimmigrant children in early adolescence is an accurate predictor of later life outcomes. Wealso examine a novel hypothesis that relative academic performance of immigrant children inhigh school compared to middle school, which could be an indicator of change in adolescentaspirations and motivation as well as the degree of adaptation and assimilation to the hostcountry, has an effect on their adult outcomes even after controlling for the levels ofacademic performance in middle and high school. The results suggest that an improvementin GPA from middle school to high school is associated with favorable adult outcomes.Several sensitivity tests confirm the robustness of main findings.

Vertical distribution of benthic invertebrate larvae during an upwelling event along a transect off the tropical Brazilian continental margin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Real power losses reduction and loading margin improvement via continuation method

This letter presents an alternative approach for reducing the total real power losses by using a continuation method. Results for two simple test systems and for the IEEE 57-bus system show that this procedure results in larger voltage stability margin. Besides, the reduction of real power losses obtained with this procedure leads to significant money savings and, simultaneously, to voltage profile improvement. Comparison between the solution of an optimal power flow and the proposed method shows that the latter can provide near optimal results and so, it can be a reasonable alternative to power system voltage stability enhancement.

Marginal and Internal Discrepancies Related to Margin Design of Ceramic Crowns Fabricated by a CAD/CAM System

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)