Estimativa do custo de produção de café agroecológico no Município de Alto Paraíso - Rondônia.

Considerando a necessidade de se gerar informações socioeconômicas que contribuam para o delineamento de agroecossistemas sustentáveis, objetivo deste trabalho é a determinação do custo de produção do café robusta em sistema agroecológico no Município de Alto Paraíso, Rondônia. Pretende-se ainda determinar a renda auferida por uma unidade de produção típica do sistema café-mel-madeira.bitstream/item/24715/1/cot317-cafeagroecologico.pd

Main steps of the Ossa Morena tectono-stratigraphic evolution, in Portugal

[Resumo] Na parte portuguesa da Zona de Ossa Morena sao identificados vários sectores com estratigrafia e estrutura diferenciadas, os quais constituem, na sua maioria, prolongamentos dos correspondentes domínios tectono-estratigráficos reconhecidos em Espanha. De norte para sul identificam-se os seguintes sectores: Faixa Blastomilonítica, Alter do Chao-Elvas, Estremoz-Barrancos (onde se diferencia o Anticlinal de Estremoz), Montemor-Ficalho (com individualizaftlo do Sinclinal de Cabrela) e o Maci~o de Beja (com o sub-sector Santa Suzana-Odivelas). Das sequencias estratigráficas e dos episódios vulcanicos intercalados é possível reconstruir os trag->s gerais da evolu~ao da 20M, em Portugal. O soco proterozóico, constituído por séries metamórficas de grau elevado a baixo, reflecte a constru~ao de urna margem passiva durante o Rifeano , que passou a urna margem activa, com subduc~ao, responsável pela Orogenia Cadomiana, durante o Vendiano. Após o arrasamento desta Cadeia Orogénica instalou-se extensa plataforma carbonatada, no Cambrico inferior, que durante o Marianiano entrou em distensao, de que resultaram várias bacias, onde localmente se gerou vulcanismo básico toleítico, que rapidamente se colmataram devido a regressao marinha generalizada. A partir do Cambrico médio reiniciou-se a distensao, que provocou o aparecimento de novas bacias sedimentares, onde se desenvolveu imponante vulcannismo básico alcalino, localmente peralcalino. Desta distensao terá resultado a rota~ao e subida de alguns blocos, o que provocou a carsifica~ao das séries carbonatadas. Sobre os sedimentos e vulcanitos do Cambrico médio depositaram-se conglomerados e arenitos de base do Ordovícico, o que indica importante lacuna no Cambrico superior. A sedimenta~ao ordovícica é predominantemente constituída por sedimentos finos, associados localmente a vulcanismo básico alcalino. Nas zonas elevadas poder-se-a ter desenvolvido vulcanismo bimodal, parcialmente peralcalino, o que mais urna vez indica a continua~ao'da distensao crustal. No topo da sequencia ordovícica ocorre extensa barra arenítica (Form'a~a:o de Colorada) sobre a qual, em transi~ao para os sedimentos silúricos, se disp5e un conglomerado poligénico, que materializa período erosivo (de origem glaciar?). Durante o Silúrico as bacias sedimentares tornaram-se euxínicas (e mais profundas a sul?) e na passagem para o Devónico predominou a sedimenta~ao terrígena e carbonatada, com características litorais. No Devónico médio deu-se o levantamento, mais ou menos generalizado, da ZOM, provocado pela actua~ao da zona de subduc~ao que se desenvolvia a sudoeste. No Devónico superior e Carbónico inferior deu-se a colisao entre as ZDnas de Ossa Morena e Sul Portuguesa, tendo ocorrido, provavelmente, obduc~ao a sudeste e subduc~o a noroeste (com gera~ao de vulcanismo orogénico). Desta colisao resultou a migra~ao de onda orogenica para nordeste a qual é responsavel pela forma~ao de bacias «pull-apart», sucessivamente mais jovens para nordeste. Da reactiva~aoda antiga zona de subdu~ao, no Namuriano-Vestfaliano inferior, agora em regime intra-continental, resultou a deforma~ao transpressiva generalizada da ZOM e da ZDna Sul Portuguesa.[Abstract] In the portuguese pan of the Ossa Morena ZDne several sectors with distinct stratigraphy and structure are identified. They represent the continuation to Portugal of well established tectono-stratigraphic domains in Spain. From north to south the following sectors are recognized: Blastomilonitic Belt, Alter do Chao-Elvas, Estremoz-Barrancos (in which the Estremoz Anticline is differentiated), Montemor-Ficalho (with the Cabrela Syncline) and Beja Massif (where the Santa Suzana-Odivelas sub-sector is outlined). The stratigraphic sequences and interbedded volcanics of the distinct sectors allow the visualization of the main steps of the OMZ tectono-stratigraphic evolution. The high to low grade metamorphic sequences of the Proterozoic basement reflect the construction of a passive margin during the Riphean, and the inversion to an active margin during the Vendian, which led to the development of the Cadomian Orogeny. After the erosion of this chain, in late Proterozoic time, a large lower Cambrian carbonate platform was build up all over the entire area. Distensive tectonism during the Marianian generated tholeitic basic volcanics and several sedimentary depocenters, which were rapidly filled up with sediments, due to a low middle Cambrian marine regression. During the middle Cambrian the distensive tectonism was renewed and, again, this led to the development of sedimentary basins (two in the portuguese part) filled up with terrigenous sediments, alcaline basalts and minor peralcaline volcanics. Tectonic blocks generated during this distension were rotated and uplifted leading to the karstification of the lower Cambrian carbonates. Lower Ordovician conglomerates and associated Fe /Mn rich sandstones Iy unconformable on the middle Cambrian sediments, indicating so an upper Cambrian gap, probably related to sardic distensive tectonism. The ordovician sediments are usually fine grained and, in places, have interbed alcaline basalts towards its base. On the uplifed blocks bimodal volcanism (partially peralcaline) took probably place, once again indicating the continuation of the crustal distension. At the top of the ordovician sediments occurs an extensive shallow water sandstone unit (Colorada Formation) which is overlain, in many places, by a metric thick poligenic conglomerate. This may represent an erosive period (related to the upper Ordovician-lower Silurian glaciation known in other parts of Iberia?). During the Silurian sedimentation was mostly euxinic and condensed in the nonhern areas, and possibly more deep in the southern ones. Shallow water terrigenous and carbonate sediments dominate in early Devonian times. During the middle Devonian generalized uplifting of the OMZ took place as a consequence of subduction movements in the south. Upper Devonian and lower Carboniferous were times of oblique collision between the OMZ and the South Ponuguese Zone, characterized by obduction in the SE and subduction (with associated orogenic volcanics) in the NW. These collisional events are responsible for the northeastward mi~ratio1). of the oro~enicwave, to which pull apan tensionallacustrine, fluvio-marine and marine basins may be related. The reactivatian of the former Benioff Zone, in an intracontinental regime, during the Namurian-lower Westfalian time, caused the widespread transpresive tectonism which affected the OMZ (and alsa the South Portuguese Zone)

Mapping the train model for earthquakes onto the stochastic sandpile model

We perform a computational study of a variant of the ``train'' model for earthquakes [PRA 46, 6288 (1992)], where we assume a static friction that is a stochastic function of position rather than being velocity dependent. The model consists of an array of blocks coupled by springs, with the forces between neighbouring blocks balanced by static friction. We calculate the probability, P(s), of the occurrence of avalanches with a size s or greater, finding that our results are consistent with the phenomenology and also with previous models which exhibit a power law over a wide range. We show that the train model may be mapped onto a stochastic sandpile model and study a variant of the latter for non-spherical grains. We show that, in this case, the model has critical behaviour only for grains with large aspect ratio, as was already shown in experiments with real ricepiles. We also demonstrate a way to introduce randomness in a physically motivated manner into the model.Comment: 14 pages and 6 figures. Accepted in European Physical Journal

Simulations of a mortality plateau in the sexual Penna model for biological ageing

The Penna model is a strategy to simulate the genetic dynamics of age-structured populations, in which the individuals genomes are represented by bit-strings. It provides a simple metaphor for the evolutionary process in terms of the mutation accumulation theory. In its original version, an individual dies due to inherited diseases when its current number of accumulated mutations, n, reaches a threshold value, T. Since the number of accumulated diseases increases with age, the probability to die is zero for very young ages (n = T). Here, instead of using a step function to determine the genetic death age, we test several other functions that may or may not slightly increase the death probability at young ages (n < T), but that decreases this probability at old ones. Our purpose is to study the oldest old effect, that is, a plateau in the mortality curves at advanced ages. Imposing certain conditions, it has been possible to obtain a clear plateau using the Penna model. However, a more realistic one appears when a modified version, that keeps the population size fixed without fluctuations, is used. We also find a relation between the birth rate, the age-structure of the population and the death probability.Comment: submitted to Phys. Rev.

A comparative study for the pair-creation contact process using series expansions

A comparative study between two distinct perturbative series expansions for the pair-creation contact process is presented. In contrast to the ordinary contact process, whose supercritical series expansions provide accurate estimates for its critical behavior, the supercritical approach does not work properly when applied to the pair-creation process. To circumvent this problem a procedure is introduced in which one-site creation is added to the pair-creation. An alternative method is the generation of subcritical series expansions which works even for the case of the pure pair-creation process. Differently from the supercritical case, the subcritical series yields estimates that are compatible with numerical simulations