Paleoenvironmental and archeological significance of alluvial placers of the Brazilian Amazon

The gold and tin-bearing alluvial placers of the Brazilian Amazon high terrains constitute a remarkable record of the environmental changes which occurred in the region during the Quaternary. The deposits are typically immature, and have been formed by mass movements under semi-arid climate. They are clearly older than the last rain forest spreading, and may be attributed to cyclic episodes which have been correlated to the Pleistocene glaciations. These interpretations are highlighted by the discovery of abundant polished stone artifacts which have been preserved within Pleistocene deposits. The archeological record allows the demarcation of an important cultural tradition, widely disseminated in the Brazilian Amazon, and gives a starting point to review our present knowledge of the Amazonian Prehistory - still centered in studies on the Várzea" region, of Holocene age. This means that the human establishment in the Amazon is much older than formerly believed

Organic carbon accumulation in coastal zones since the last glacial maximum? A clue for varying atmospheric CO2 levels?

It is a generally accepted concept that the carbon storage within the principal earth surface reservoirs varies in a multitude of time scales. The shallow water continental margins belong to the most fertile areas in terms of organic carbon (OC) production and are also very effective carbon traps

Sistemas silvipastoris na Amazônia Oriental.

A problemática das pastagens. Os sistemas silvipastoris (SSP). O papel da árvore. Interação árvore - pastagem. Componente animal. Sistemas silvipastoris praticados na Amazônia Oriental. Avaliação de sistemas silvipastoris. Adoção de sistemas silvipastoris.bitstream/item/63268/1/Oriental-Doc56.pd

Mesophilic and thermophilic biotreatment of BTEX-polluted air in reactors

This study compares the removal of a mixture of benzene, toluene, ethylbenzene, and all three xylene isomers (BTEX) in mesophilic and thermophilic (50°C) bioreactors. In the mesophilic reactor fungi became dominant after long-term operation, while bacteria dominated in the thermophilic unit. Microbial acclimation was achieved by exposing the biofilters to initial BTEX loads of 2–15 g m−3 h−1, at an empty bed residence time of 96 s. After adaptation, the elimination capacities ranged from 3 to 188 g m−3 h−1, depending on the inlet load, for the mesophilic biofilter with removal efficiencies reaching 96%. On the other hand, in the thermophilic reactor the average removal efficiency was 83% with a maximum elimination capacity of 218 g m−3 h−1. There was a clear positive relationship between temperature gradients as well as CO2 production and elimination capacities across the biofilters. The gas phase was sampled at different depths along the reactors observing that the percentage pollutant removal in each section was strongly dependant on the load applied. The fate of individual alkylbenzene compounds was checked, showing the unusually high biodegradation rate of benzene at high loads under thermophilic conditions (100%) compared to its very low removal in the mesophilic reactor at such load (<10%). Such difference was less pronounced for the other pollutants. After 210 days of operation, the dry biomass content for the mesophilic and thermophilic reactors were 0.300 and 0.114 g g−1support, respectively, reaching higher removals under thermophilic conditions with a lower biomass accumulation, that is, lower pressure drop

The material sources and processes during the infilling of estuaries in Algarve (South Portugal)

The actual estuary that occupies the Boina-Arade paleovalley accommodated the Holocene sedimentary sequence whose thickness does not exceed 35 m in the deepest zones, as registered from geotechnical borehole data. We present here the results of partial analyses of two continuous cores which cross the Holocene sequence until the Pre-Quaternary substratum. In the P5 core (Boina river), the sedimentary column, which spans 20 m accumulated during ca 8500 years

Shore Platforms in the Algarve (South Portugal) Rocky Coast, an Inheritance of the Last Interglacial Stage?

Shore platforms, notches, and marine caves are common yet distinctive morphological features along the southern coast of Portugal. The central Algarve rocky coast has provided a favorable setting in which to understand the processes contributing to shore platform development. This is because the morphology and characteristics of the features vary along the coast, as do several factors implicated in their development such as wave climate (including wave direction and frequency), seabed morphology and depth, bedrock lithology, karstification and geological structure

Public debt, economic growth, and inflation in African economies

We analyse the relationship between public debt, economic growth and inflation in a group of 52 African economies between 1950 and 2012. The results indicate that the limits of public debt are negatively related to economic growth and exhibit, from a given level of debt, an inverted U behaviour regarding the relationship between economic growth and public debt. Briefly, the high levels of public debt are coincident with reduced rates of economic growth and rising levels of inflation. Our results for three specific geographical areas resemble those of the overall analysis, despite some differences. In North African countries, the growth rates of the GDP and inflation also show an inverted U behaviour as the ratio of public debt/GDP increases. The highest rate of economic growth is recorded when the ratio public debt/GDP is below 30% of GDP and corresponds to an average inflation rate of 5.33%. Identical behaviour of the GDP growth rates and inflation also appears in Sub-Saharan countries until the third interval (60-90%). However, the highest growth rate of the GDP and GDP per capita is registered when the public debt/GDP ratio is in the second interval (30-60%). For SADC countries, the highest average rate of economic growth (6.8%) is similar to North African countries, when the ratio public debt/GDP is below 30% of GDP, with an average inflation rate of 11%. A number of robustness analyses were performed and the great majority of them confirm the general analysis.info:eu-repo/semantics/acceptedVersio

“In vitro” comparative experimental study of antimicrobial action of mouth washing products

Regular use of mouth rinses modifies the oral habitat, since bacterial populations are submitted to a high selective pressure during the treatment exercised by the active presence of the disinfectant. Mostly mouth rinses are based on the antibacterial effect of Chlorhexidine, Triclosan, essential oils and other antibacterials although other pharmaceutical characteristics can also affect their effectiveness. In this paper we compare “in vitro” the antibacterial effect of different oral rinsing solutions. Minimal Inhibitory Concentrations (MIC) and Minimal Bactericidal Concentrations (MBC) were determined as well as the kinetics of bacterial death in the presence of letal concentrations of the mouth rinses. MIC values expressed as Maximal Inhibitory Dilution (MID) of the mouth rinse ranged from 1 to 1/2048 depending on the microorganism and product, whereas Minimal Biocidal Concentration (MBC), expressed as Maximal Biocidal Dilution (MBD) ranged from 1 to 1/1024, being in general one dilution less than MIC. Maximal Biocidal Dilution is a good tool to measure the actual efficiency of mouth washing solutions. However, kinetics of death seems to be better in our work killing curves demonstrate that bacterial populations are mostly eliminated during the first minute after the contact of bacterial suspension and the mouth-washing solution. In all tested bacterial species mouth-washing solutions tested were able to reduce until suspension treated except 1 and 5