Pathways of recent fine-grained sediment transport on the central Portuguese continental margin

Com o intuito de estudar as principais vias de transporte de sedimentos finos recentes na zona central da margem continental Oeste Portuguesa, parâmetros geoquímicos, mineralógicos e granulométricos foram analisados em sedimentos superficiais e em matéria particulada colhida em armadilhas de sedimentos e integrados com observações da hidrodinâmica de fundo. Os parâmetros geoquímicos foram também estudados na coluna de sedimentos depositada nos últimos 150 anos e em sedimentos pré-industriais. Os referidos parâmetros determinados foram: concentrações elementares, isótopos estáveis de Pb, teores em materiais litogénicos, carbonato de cálcio e carbono orgânico. Os canhões de Lisboa-Setúbal e Cascais tiveram especial destaque no presente estudo dado que, até à data, encontram-se menos estudados que o Canhão da Nazaré. Os resultados mostram que a distribuição de sedimentos na zona central da margem ocidental Portuguesa é particionada pelos canhões e que a exportação de sedimentos da plataforma para zonas mais profundas da margem é restringida pelas correntes do talude, excepto onde os canhões funcionam como corredores para o transporte de sedimentos. Enquanto no Canhão de Lisboa-Setúbal, e provavelmente no Canhão de Cascais, o transporte de sedimentos até à zona inferior é limitada, provavelmente apenas despoletado por eventos de elevada energia, no Canhão da Nazaré o transporte ao longo do todo o canhão parece eficiente. As zonas superiores dos canhões de Lisboa-Setúbal e Cascais presentemente actuam como armadilhas de sedimentos finos, aprisionando partículas em suspensão provenientes da plataforma adjacente. A introdução directa de sedimentos provenientes das plumas dos rios Tejo e Sado nas zonas superiores dos canhões parece limitada, contudo a resuspensão dos sedimentos do prodelta do Tejo como resultado de ondas de tempestade e ondas de maré interna permite o transporte de sedimentos para os canhões adjacentes. Na plataforma de Lisboa-Setúbal-Sines foram identificadas as assinaturas geoquímicas e mineralógicas de diferentes fontes de sedimentos finos (e.g. estuários do Tejo e Sado, arribas costeiras, lagoas de St. André e Melides). As concentrações elementares pré-industriais são muito semelhantes nos canhões da Nazaré e Lisboa-Setúbal, mas variados graus de enriquecimento antrópico de metais traço estão presentes nos sedimentos recentes. A mais acentuada influência antrópica na última área referida é consistente com a sua proximidade a áreas densamente povoadas e industrializadas e com input de sedimentos originários dos rios Tejo e Sado, potenciais transportadores de partículas poluentes. A dispersão de Pb atmosférico parece também significativa sendo que toda a zona da plataforma continental adjacente aos canhões de Lisboa-Setúbal e Cascais apresenta-se enriquecida. A principal fonte de Pb antrópico identificada através de isótopos estáveis de Pb é consistente com a assinatura das cinzas de incineradoras. No Canhão de Lisboa a imersão de dragados contaminados parece ser também uma potencial importante fonte de metais traço antropogénicos.

Modeling the Western Iberian margin circulation: present and future

The purpose of this work is to carry out a comprehensive study on the Western Iberian Margin (WIM) circulation my means of numerical modeling, and to postulate what this circulation will be in the future. The adopted approach was the development of a regional ocean model configuration with high resolution, capable of reproducing the largeand small-scale dynamics of the coastal transition zone. Four numerical experiences were carried out according to these objectives: (1) a climatological run, in order to study the system’s seasonal behavior and its mean state; (2) a run forced with real winds and fluxes for period 2001-2011 in order to study the interannual variability of the system; (3) a run forced with mean fields from Global Climate Models (GCMs) for the present, in order to validate GCMs as adequate forcing for regional ocean modeling; (4) a similar run (3) for period 2071-2100, in order to assess possible consequences of a future climate scenario on the hydrography and dynamics of the WIM. Furthermore, two Lagrangian particle studies were carried out: one in order to trace the origin of the upwelled waters along the WIM; the other in order to portrait the patterns of larval dispersal, accumulation and connectivity. The numerical configuration proved to be adequate in the reproduction of the system’s mean state, seasonal characterization and an interannual variability study. There is prevalence of poleward flow at the slope, which coexists with the upwelling jet during summer, although there is evidence of its shifting offshore, and which is associated with the Mediterranean Water flow at deeper levels, suggesting a barotropic character. From the future climate scenario essay, the following conclusions were drawn: there is general warming and freshening of upper level waters; there is still poleward tendency, and despite the upwellingfavorable winds strengthening in summer the respective coastal band becomes more restricted in width and depth. In what concerns larval connectivity and dispersion along the WIM, diel vertical migration was observed to increase recruitment throughout the domain, and while smooth coastlines are better suppliers, there is higher accumulation where the topography is rougher.

Dynamics and variability of the alongshore flows on the northwestern iberian margin

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Oceanografia), Universidade de Lisboa, Faculdade de Ciências, 2014

Synthesis of the Piacenzian onshore record between the Aveiro and Setubal parallels (Western portuguese margin)

Onshore, the Piacenzianof the Mondego and Lower Tagus Tertiary basins comprises siliciclastic sediments deposited in shallow marine to continental environments. The outcrops of the deposits are relatively widespread in the Aveiro and Seuibal region. A lithostratigraphic synthesis based on the correlation of geological sections, is presented for the two basins. In general, the Piacenzian sediments display a regressive sucession. The Late Tortonian-Zanclean (?) confined drainage pattern changed at the beginning of Piazencian, to fluvial systems draining to the Atlantic, and capturing the drainage of the inner parts of the Hesperic Meseta. The Piacenzian sedimentary sequence post-dates one of the uprising phases during Neogene compression, recorded by a strong regional unconformity. Some local active faulting - as in Lousa, Rio Maior and Senibal- Pinhal Novo - allowed the local thickening of the sedimentary record. Later compressive tectonism continues to generate reverse faulting and diapiric reactivation, affecting those sediments. Currently, the Piacenzian deposits culminates the marginal piedmonts, widely eroded by the Quaternary fluvial dissection.

Continental margin architecture : the palynological signature of glacioeustasy /

Palynomorphs from two siliciclastic margins were examined to gain insights into continental margin architecture. Sea level change is thought to be one of the primary controls on continental margin architecture. Because Late Neogene glacioeustasy has been well studied marine sediments deposited during the Late Neogene were examined to test this concept. Cores from the outer shelf and upper slope were taken from the New Jersey margin in the western North Atlantic Ocean and from the Sunda Shelf margin in the South China Sea. Continental margin architecture is often described in a sequence stratigraphic context. One of the main goals of both coring projects was to test the theoretical sequence stratigraphic models developed by a research group at Exxon (e.g. Wilgus et al., 1988). Palynomorphs provide one of the few methods of inferring continental margin architecture in monotonous, siliciclastic marine sediments where calcareous sediments are rare (e.g. New Jersey margin). In this study theoretical models of the palynological signature expected in sediment packages deposited during the various increments of a glacioeustatic cycle were designed. These models were based on the modem palynomorph trends and taphonomic factors thought to control palynomorph distribution. Both terrestrial (pollen and spores) and marine (dinocysts) palynomorphs were examined. The palynological model was then compared with New Jersey margin and Sunda Shelf margin sediments. The predicted palynological trends provided a means of identifying a complete cycle of glacioeustatic change (Oxygen Isotope Stage 5e to present) in the uppermost 80 meters of sediment on the slope at the New Jersey margin. Sediment availability, not sea meters of sediment on the slope at the New Jersey margin. Sediment availability, not sea level change, is thought to be the major factor controlling margin architecture during the late Pleistocene here at the upper slope. This is likely a function of the glacial scouring of the continents which significantly increases sediment availability during glacial stages. The subaerially exposed continental shelf during the lowstand periods would have been subject to significant amounts of erosion fi:om the proglacial rivers flowing fi-om the southern regions of the ice-sheet. The slope site is non-depositional today and was also non-depositional during the last full interglacial period. The palynomorph data obtained fi-om the South China Sea indicate that the major difference between the New Jersey Margin sites and the Sunda Shelf margin sites is the variation in sediment supply and the rate of sediment accumulation. There was significantly less variation in sediment supply between glacial and interglacial periods and less overall sediment accumulation at the Sunda Shelf margin. The data presented here indicate that under certain conditions the theoretical palynological models allow the identification of individual sequence stratigraphic units and therefore, allow inferences regarding continental margin architecture. The major condition required in this approach is that a complete and reliable database of the contemporaneous palynomorphs be available.

Margin requirements and volatility : evidence from Canadian stocks

Margin policy is used by regulators for the purpose of inhibiting exceSSIve volatility and stabilizing the stock market in the long run. The effect of this policy on the stock market is widely tested empirically. However, most prior studies are limited in the sense that they investigate the margin requirement for the overall stock market rather than for individual stocks, and the time periods examined are confined to the pre-1974 period as no change in the margin requirement occurred post-1974 in the U.S. This thesis intends to address the above limitations by providing a direct examination of the effect of margin requirement on return, volume, and volatility of individual companies and by using more recent data in the Canadian stock market. Using the methodologies of variance ratio test and event study with conditional volatility (EGARCH) model, we find no convincing evidence that change in margin requirement affects subsequent stock return volatility. We also find similar results for returns and trading volume. These empirical findings lead us to conclude that the use of margin policy by regulators fails to achieve the goal of inhibiting speculating activities and stabilizing volatility.

Modified Large Margin Nearest Neighbor Metric Learning for Regression

The main objective of this letter is to formulate a new approach of learning a Mahalanobis distance metric for nearest neighbor regression from a training sample set. We propose a modified version of the large margin nearest neighbor metric learning method to deal with regression problems. As an application, the prediction of post-operative trunk 3-D shapes in scoliosis surgery using nearest neighbor regression is described. Accuracy of the proposed method is quantitatively evaluated through experiments on real medical data.

Moving from Margin to Mainstream

School of Management Studies,Cochin University of Science and Technology

Dynamics of Rifting Along the Southwest Continental margin of India Through Coherence and Process oriented Analysis of Gravity Data

Department of Marine Geology and Geophysics,Cochin University of Science and Technology

Macrobenthosof the cotinental margin(200-1000 m) of South Eastern Arabian Sea with special reference to Polychaetes

This thesis Entitled macrobenthos of the continental margin (200-1000m) of south eastern arabian sea with special reference to polychaetes. The continental margins are geologically complex and hydrodynamically active regions of the ocean, where vital biogeochemical processes take place from a global perspective. The Eastern Arabian Sea is one of the most productive regions of the world, and as a result, vast amount of organic matter is supplied to the sub surface waters and sea bed of the Arabian Sea. In this study, data on faunal abundance, standing crop and faunal composition, together with sedimentary and environmental parameters were collected from three depths (200m, 500m & 1000m) in nine bathymetric transects along the South Eastern Arabian Sea (from Cape Comorin to Karwar) during three surveys. In the present study, five textural classes of sediments were identified from the SEAS margin, viz. sand, silty sand, sandy silt, clayey silt and admixture of sand, silt and clay. The composition of sand was higher in the southern region and decreased progressively towards the north. On the shelf edge and upper slope regions in the south (Cape to Kollam) in particular, sandy sediments dominated .

Uncover the Concealed Link: Gender & Ethnicity-Divided Local Knowledge on the Agro-Ecosystem of a Forest Margin

This research is a study about knowledge interface that aims to analyse knowledge discontinuities, the dynamic and emergent characters of struggles and interactions within gender system and ethnicity differences. The cacao boom phenomenon in Central Sulawesi is the main context for a changing of social relations of production, especially when the mode of production has shifted or is still underway from subsistence to petty commodity production. This agrarian change is not only about a change of relationship and practice, but, as my previous research has shown, also about the shift of knowledge domination, because knowledge construes social practice in a dialectical process. Agroecological knowledge is accumulated through interaction, practice and experience. At the same time the knowledge gained from new practices and experiences changes mode of interaction, so such processes provide the arena where an interface of knowledge is manifested. In the process of agro-ecological knowledge interface, gender and ethnic group interactions materialise in the decision-making of production and resource allocation at the household and community level. At this point, power/knowledge is interplayed to gain authority in decision-making. When authority dominates, power encounters resistance, whereas the dominant power and its resistance are aimed to ensure socio-economic security. Eventually, the process of struggle can be identified through the pattern of resource utilisation as a realisation of production decision-making. Such processes are varied from one community to another, and therefore, it shows uniqueness and commonalities, especially when it is placed in a context of shifting mode of production. The focus is placed on actors: men and women in their institutional and cultural setting, including the role of development agents. The inquiry is informed by 4 major questions: 1) How do women and men acquire, disseminate, and utilise their agro ecological knowledge, specifically in rice farming as a subsistence commodity, as well as in cacao farming as a petty commodity? How and why do such mechanisms construct different knowledge domains between two genders? How does the knowledge mechanism apply in different ethnics? What are the implications for gender and ethnicity based relation of production? ; 2) Using the concept of valued knowledge in a shifting mode of production context: is there any knowledge that dominates others? How does the process of domination occur and why? Is there any form of struggle, strategies, negotiation, and compromise over this domination? How do these processes take place at a household as well as community level? How does it relate to production decision-making? ; 3) Putting the previous questions in two communities with a different point of arrival on a path of agricultural commercialisation, how do the processes of struggle vary? What are the bases of the commonalities and peculiarities in both communities?; 4) How the decisions of production affect rice field - cacao plantation - forest utilisation in the two villages? How does that triangle of resource use reflect the constellation of local knowledge in those two communities? What is the implication of this knowledge constellation for the cacao-rice-forest agroecosystem in the forest margin area? Employing a qualitative approach as the main method of inquiry, indepth and dialogic interviews, participant observer role, and document review are used to gather information. A small survey and children’s writing competition are supplementary to this data collection method. The later two methods are aimed to give wider information on household decision making and perception toward the forest. It was found that local knowledge, particularly knowledge pertaining to rice-forest-cacao agroecology is divided according to gender and ethnicity. This constellation places a process of decision-making as ‘the arena of interface’ between feminine and masculine knowledge, as well as between dominant and less dominant ethnic groups. Transition from subsistence to a commercial mode of production is a context that frames a process where knowledge about cacao commodity is valued higher than rice. Market mechanism, as an external power, defines valued knowledge. Valued knowledge defines the dominant knowledge holder, and decision. Therefore, cacao cultivation becomes a dominant practice. Its existence sacrifices the presence of rice field and the forest. Knowledge about rice production and forest ecosystem exist, but is less valued. So it is unable to challenge the domination of cacao. Various forms of struggles - within gender an ethnicity context - to resist cacao domination are an expression of unequal knowledge possession. Knowledge inequality implies to unequal access to withdraw benefit from market valued crop. When unequal knowledge fails to construct a negotiated field or struggles fail to reveal ‘marginal’ decision, e.g. intensification instead of cacao expansion to the forest, interface only produces divergence. Gender and ethnicity divided knowledge is unabridged, since negotiation is unable to produce new knowledge that accommodates both interests. Rice is loaded by ecological interest to conserve the forest, while cacao is driven by economic interest to increase welfare status. The implication of this unmediated dominant knowledge of cacao production is the construction of access; access to the forest, mainly to withdraw its economic benefit by eliminating its ecological benefit. Then, access to cacao as the social relationship of production to acquire cacao knowledge; lastly, access to defend sustainable benefit from cacao by expansion. ‘Socio-economic Security’ is defined by Access. The convergence of rice and cacao knowledge, however, should be made possible across gender and ethnicity, not only for the sake of forest conservation as the insurance of ecological security, but also for community’s socio-economic security. The convergence might be found in a range of alternative ways to conduct cacao sustainable production, from agroforestry system to intensification.

A Note on the Generalization Performance of Kernel Classifiers with Margin

We present distribution independent bounds on the generalization misclassification performance of a family of kernel classifiers with margin. Support Vector Machine classifiers (SVM) stem out of this class of machines. The bounds are derived through computations of the $V_gamma$ dimension of a family of loss functions where the SVM one belongs to. Bounds that use functions of margin distributions (i.e. functions of the slack variables of SVM) are derived.

Parametric pension reform and the intensive margin of labor supply, evidence from Colombia

We analyze the effect of a parametric reform of the fully-funded pension regime in Colombia on the intensive margin of the labor supply. We take advantage of a threshold defined by law in order to identify the causal effect using a regression discontinuity design. We find that a pension system that increases retirement age and the minimum weeks during which workers must contribute to claim pension benefits causes an increase of around 2 hours on the number of weekly worked hours; this corresponds to 4% of the average number of weekly worked hours or around 14% of a standard deviation of weekly worked hours. The effect is robust to different specifications, polynomial orders and sample sizes.

Bt-cotton boosts the gross margin of small-scale cotton producers in South Africa

This paper explores some of the issues involved in the Genetic Modification (GM) debate by focusing on one crop that has been modified for pest resistance, cotton (Gossypium hirsutum), and commercially released to small-scale farmers in the Makhathini Flats, KwaZulu Natal, the Republic of South Africa. This was the first commercial release of a GM variety (Bt-cotton) in Sub-Saharan Africa, and thus provides valuable and timely insights into some of the potential advantages and disadvantages of the technology for small-scale farmers in Africa. Even though there are wider concerns regarding the vulnerability of small-scale farmers in the area, the survey results suggest that Bt-cotton generated higher yields and gross margins than non-Bt-cotton. In addition, Bt-cotton significantly reduced the use of pesticide with consequent potential benefits to human health and the environment.