Uppermost Miocene Lamniform Selachians (Pisces) from the Alvalade basin (Portugal)

This paper deals with Lamniform teeth collected in deposits from the Esbarrondadoiro Formation, Alvalade Basin in Southern Portugal. The following genera were recognized: Carcharias, Pseudocarcharias, Alopias, Isurus and Carcharocles. The species Carcharias acutissima is by far the most predominant, all other taxa being rare or very rare. This situation points to neritic, tropical to subtropical, rather shallow waters not far away from the coast. This is corroborated by the rarity of the associated, mainly pelagic, taxa. The ratio between C. acutissima and the remaining Lamniforms as a whole is markedly uneven between Esbarrondadoiro and the localities of Santa Margarida and Vale de Zebro. This suggests quite different environmental conditions, a matter that will require a more thorough examination taking into account all palaeontologic and geologic data

Inequivalent Z2nZ_2^n-graded brackets, nn-bit parastatistics and statistical transmutations of supersymmetric quantum mechanics

Given an associative ring of $Z_2^n$-graded operators, the number of inequivalent brackets of Lie-type which are compatible with the grading and satisfy graded Jacobi identities is $b_n= n+\lfloor n/2\rfloor+1$. This follows from the Rittenberg-Wyler and Scheunert analysis of "color" Lie (super)algebras which is revisited here in terms of Boolean logic gates. The inequivalent brackets, recovered from $Z_2^n\times Z_2^n\rightarrow Z_2$ mappings, are defined by consistent sets of commutators/anticommutators describing particles accommodated into an $n$-bit parastatistics (ordinary bosons/fermions correspond to $1$ bit). Depending on the given graded Lie (super)algebra, its graded sectors can fall into different classes of equivalence expressing different types of (para)bosons and/or (para)fermions. As a first application we construct $Z_2^2$ and $Z_2^3$-graded quantum Hamiltonians which respectively admit $b_2=4$ and $b_3=5$ inequivalent multiparticle quantizations (the inequivalent parastatistics are discriminated by measuring the eigenvalues of certain observables in some given states). As a main physical application we prove that the $N$-extended, $1D$ supersymmetric and superconformal quantum mechanics, for $N=1,2,4,8$, are respectively described by $s_{N}=2,6,10,14$ alternative formulations based on the inequivalent graded Lie (super)algebras. These numbers correspond to all possible "statistical transmutations" of a given set of supercharges which, for ${N}=1,2,4,8$, are accommodated into a $Z_2^n$-grading with $n=1,2,3,4$ (the identification is $N= 2^{n-1}$). In the simplest ${N}=2$ setting (the $2$-particle sector of the de DFF deformed oscillator with $sl(2|1)$ spectrum-generating superalgebra), the $Z_2^2$-graded parastatistics imply a degeneration of the energy levels which cannot be reproduced by ordinary bosons/fermions statistics.Comment: 57 pages, 16 figure

Consequences of transformation of native Cerrado in pasture land on the porosity of a clayey-sand red latosol

In the Brazilian savannah (Cerrados area), about 60 % of the surface area is used as pasture land and 30 % of the latter is cultivated pasture. Many studies have reported that pastures degrade quickly and degradation would be more intense when the soil was tilled prior pasture sowing. Pasture degradation (decrease in the pasture quality and yield, weed invasion) would be partly a consequence of the soil structure evolution (Balbino & Di Stefano, 1999). Origin of pasture degradation is still under discussion and analysis of the literature showed that there is a lack of quantitative data. The aim of this study is to perform a detailed analysis of the porosity in a low productivity cultivated pasture and to compare the results with the porosity of a similar soil still under native vegetation (Cerradão, i.e. Scierophylous forest)

Study of storage sunrise "Solo" papaya fruit under controlled atmosphere.

The effécts of controlled atmophere (CA) on keeping quality of stored 'Solo' papaya (Carica Papaya L. ) fiuit was studied

Change in the hydraulic properties of a Brazilian clay Ferralsol on clearing for pasture.

32 ref. doi: 10.1016/j.geoderma.2003.08.017Ferralsols under native vegetation have a weak to moderate macrostructure and a well-developed microstructure corresponding to subrounded microaggregates that are usually 80 to 300 μm in size. The aim of this study was to analyze how the hydraulic properties of a clay Ferralsol were affected by a change of structure when the native vegetation is cleared for pasture. We studied the macrostructure in the field and microstructure in scanning electron microscopy. The water retention properties were determined by using pressure cell equipment. We determined the saturated hydraulic conductivity, Ks, by applying a constant hydraulic head to saturated core samples, and the unsaturated hydraulic conductivity, K(Ψ), by applying the evaporation method to undisturbed core samples. Results showed a significant decrease in the water retained at −1 and −10 hPa from 0- to 40-cm-depth when the native vegetation is cleared for pasture. That decrease in the water retained was related to a smaller development of microaggregation and greater proportion of microaggregates in close packing. For smaller water potential, there was no difference of water retained at every depth between native vegetation and pasture. Pedotransfer functions established earlier for Brazilian Ferralsols and using clay content as single predictor gave pretty good results but the precision of the estimation decreased when the water potential increased. This decrease in the precision was related to the lack of predictor taking structure into account. Ks and K(Ψ) showed an upward trend with depth under native vegetation and pasture. Except at 0–7-cm depth between the Brachiaria clumps in the pasture where smaller Ks and K(Ψ) than at the other depth was recorded whatever land use, we did not record any significant difference of Ks and K(Ψ) at every depth between native vegetation and pasture. The upward trend shown by the hydraulic conductivity with depth was related to the increase in the development of microaggregation with depth

Resistência mecânica do solo à penetração afetada pela presença de braquiária em sistemas de rotação de culturas.

Este trabalho teve por objetivo avaliar o efeito da braquiária em sistemas de rotação de culturas em plantio direto na resistência mecânica do solo à penetração

The Cristo Rei section (Lower Miocene). Distal fluviatile environments in a marine series, plants, vertebrates and other evidence, age

The section at Cristo Rei shows sandy beds with intercalated clayey lenses (IVb division from the Lisbon Miocene series) that correspond to a major regression event dated from between ca. 17.6 and 17 Ma. They also correspond to a distal position (relatively to the typical fluviatile facies in Lisbon), nearer the basin's axis. Geologic data and paleontological analysis (plant fossils, fishes, crocodilians, land mammals) allow the reconstruction of environments that were represented in the concerned area: estuary with channels and ox-bows; upstream, areas occupied by brackish waters where Gryphaea griphoides banks developped; still farther upstream, freshwaters sided by humid forests and low mountain subtropical forests under warm temperate and rainy conditions, as well as not far away, seasonally dry environments (low density tree or shrub cover, or steppe)

Mineral content in semiarid grassland systems affected by community structure and soil characteristics

This work was supported by the European Union project nº 8001-CT90-0021.Mineral element concentrations in plants and their relationships with botanical composition and soil characteristics were analyzed over two consecutive years in herbage samples from semiarid grassland systems (central-western Spain) affected by a topographic gradient. There were not significant differences in the mineral concentration of the plant community between sampling years suggesting that factors other than those related to interannual climatic variation are more important in determining the mineral concentration of plant community in semiarid grasslands. A significant effect of slope position on aboveground biomass production, soil characteristics and plant tissue nutrient contents was found. As compared to the upper and middle zones, the lower zones of slope showed greater aboveground biomass production, a lower proportion of forbs, a higher proportion of grasses, higher concentrations of N, Ca, Mg and Na in botanical groups, and lower concentrations of P and K in botanical components. Stepwise multiple regression analysis showed that most of the variation in N, P, K, Ca, and Mg concentrations in the plant community along the slope can be explained by botanical composition and its specific mineral content. Several soil properties (organic matter, total N, total C, coarse sand) proved to be significantly correlated with the N, Ca, Mg, and Na concentrations of grasses, legumes and forbs, indicating an increase in plant tissue concentrations with increasing eutrophic status in soil from the upper to the lower zones of the slope. The P and K concentrations of legumes and forbs varied according to the phosphorus or potassium contents in soil, which decreased from the upper and middle to the lower zones. The results showed that the mineral concentrations of botanical components were dependent on soil characteristics in different ways.Peer reviewe