980 resultados para fossil


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Cariria orbiculiconiformis gen. nov. et spec. nov., a gymnosperm with gnetoid characters is described from the upper Aptian Crato Formation of the Araripe Basin in northeastern Brazil. Gross-morphology and anatomical details have been studied and characters have been discussed in respect to various seed plants. Several of these characters fit best with those of Gnetales and their putative fossil allies. However, the fossil plant cannot be assigned to any known extinct or extant group of seed plants in their current circumscription. Stem gross-morphology, xylotomical characters and epidermal features indicate a gnetophytic relationship, whereas characters of the reproductive organs are rather distinct from those found in extant taxa. The reproductive unit of the new taxon represents a triple organ consisting of two dichasial ovulate structures and one median pollen-producing structure containing smooth, monosulcate, boat-shaped pollen in-situ. Each ovulate structure consists of two distinct pairs of bracts, a sterile one at the base and a fertile one forming a terminal orbicular capsule. Stiff processes found in the apex of the ovulate structure may represent micropylar tubes of seeds, as seen in the Bennettitales-Erdtmanithecales-Gnetales group. C orbiculiconiformis gen. nov. et spec. nov. was ans herbaceous or semi-shrub-like plant that may have been adapted to the r-strategy in a stressful environment. (C) 2011 Elsevier B.V. All rights reserved.

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International carbon credit markets are based in differences between developing and developed countries greenhouse gases emissions mitigation costs and technological limits faced by developed countries. Potential of energy efficiency measures to reduce fossil fuel usage in Brazilian industrial segments is assessed, and analysis of such potentials singles out those segments and regions more apt to generate carbon credits through Clean Development Mechanism (CDM) projects. Though there are currently few Brazilian CDM projects, their number may be significantly increased, which is a positive outcome. For this purpose, it is crucial that energy conservation programs estimate how CDM may improve their economic competitiveness.

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One of the main aims of this thesis is to design an optimized commercial Photovoltaic (PV) system in Barbados from several variables such as racking type, module type and inverter type based on practicality, technical performance as well as financial returns to the client. Detailed simulations are done in PVSYST and financial models are used to compare different systems and their viability. Once the preeminent system is determined from a financial and performance perspective a detailed design is done using PVSYST and AutoCAD to design the most optimal PV system for the customer. In doing so, suitable engineering drawings are generated which are detailed enough for construction of the system. Detailed cost with quotes from relevant manufacturers, suppliers and estimators become instrumental in determining Balance of System Costs in addition to total project cost. The final simulated system is suggested with a PV capacity of 425kW and an inverter output of 300kW resulting in an array oversizing of 1.42. The PV system has a weighted Performance Ratio of 77 %, a specific yield of 1467 kWh/kWp and a projected annual production of 624 MWh/yr. This system is estimated to offset approximately 28 % of Carlton’s electrical load annually. Over the course of 20 years the PV system is projected to produce electricity at a cost of $0.201USD/kWh which is significantly lower than the $0.35 USD/kWh paid to the utility at the time of writing this thesis. Due to the high cost of electricity on the island, an attractive Feed-In-Tariff is not necessary to warrant the installation of a commercial System which over a lifetime which produces electricity at less than 60% of the cost to the user purchasing electricity from the utility. A simple payback period of 5.4 years, a return on investment of 17 % without incentives, in addition to an estimated diversion of 6840 barrels of oil or 2168 tonnes of CO2 further provides compelling justification for the installation of a commercial Photovoltaic System not only on Carlton A-1 Supermarket, but also island wide as well as regionally where most electricity supplies are from imported fossil fuels.

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Did Neanderthals have language? This issue has been debated back and forth for decades, without resolution. But in recent years new evidence has become available. New fossils and archeological finds cast light on relevant Neanderthal anatomy and behavior. New DNA evidence, both fossil and modern, provides clues both to the relationship between Neanderthals and Homo sapiens, and to the genetics of language. In this paper, I review and evaluate the available evidence. My conclusion is that the preponderance of the evidence supports the presence of some form of language in Neanderthals.

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Objective: For the evaluation of the energetic performance of combined renewable heating systems that supply space heat and domestic hot water for single family houses, dynamic behaviour, component interactions, and control of the system play a crucial role and should be included in test methods. Methods: New dynamic whole system test methods were developed based on “hardware in the loop” concepts. Three similar approaches are described and their differences are discussed. The methods were applied for testing solar thermal systems in combination with fossil fuel boilers (heating oil and natural gas), biomass boilers, and/or heat pumps. Results: All three methods were able to show the performance of combined heating systems under transient operating conditions. The methods often detected unexpected behaviour of the tested system that cannot be detected based on steady state performance tests that are usually applied to single components. Conclusion: Further work will be needed to harmonize the different test methods in order to reach comparable results between the different laboratories. Practice implications: A harmonized approach for whole system tests may lead to new test standards and improve the accuracy of performance prediction as well as reduce the need for field tests.