970 resultados para Ostracoda, Fossil.
Resumo:
Leptoconops nosopheris sp. n. (Diptera: Ceratopogonidae) is described from a blood-filled female biting midge in Early Cretaceous Burmese amber. The new species is characterized by a very elongate terminal flagellomere, elongate cerci, and an indistinct spur on the metatibia. This biting midge contained digenetic trypanosomes (Kinetoplastida: Trypanosomatidae) in its alimentary tract and salivary glands. These trypanosomes are described as Paleotrypanosoma burmanicus gen. n., sp. n., which represents the first fossil record of a Trypanosoma generic lineage.
Resumo:
The understanding of sedimentary evolution is intimately related to the knowledge of the exact ages of the sediments. When working on carbonate sediments, age dating is commonly based on paleontological observations and established biozonations, which may prove to be relatively imprecise. Dating by means of strontium isotope ratios in marine bioclasts is the probably best method in order to precisely date carbonate successions, provided that the sample reflects original marine geochemical characteristics. This requires a precise study of the samples including its petrography, SEM and cathodoluminescence observations, stable carbon and oxygen isotope geochemistry and finally the strontium isotope measurement itself. On the Nicoya Peninsula (Northwestern Costa Rica) sediments from the Piedras Blancas Formation, Nambi Formation and Quebrada Pavas Formation were dated by the means of strontium isotope ratios measured in Upper Cretaceous Inoceramus shell fragments. Results have shown average 87Sr/86Sr values of 0.707654 (middle late Campanian) for the Piedras Blancas Formation, 0.707322 (Turonian-Coniacian) for the Nambi Formation and 0.707721 (late Campanian-Maastrichtian) for the Quebrada Pavas Formation. Abundant detrital components in the studied formations constitute a difficulty to strontium isotope dating. In fact, the fossil bearing sediments can easily contaminate the target fossil with strontium mobilized form basalts during diagenesis and thus the obtained strontium isotope ratios may be influenced significantly and so will the obtained ages. The new and more precise age assignments allow for more precision in the chronostratigraphic chart of the sedimentary and tectonic evolution of the Nicoya Peninsula, providing a better insight on the evolution of this region. Meteor Cruise M81 dredged shallow water carbonates from the Hess Rise and Hess Escarpment during March 2010. Several of these shallow water carbonates contain abundant Larger Foraminifera that indicates an Eocene-Oligocene age. In this study the strontium isotope values ranging from 0.707847 to 0.708238 can be interpreted as a Rupelian to Chattian age of these sediments. These platform sediments are placed on seamounts, now located at depths reaching 1600 m. Observation of sedimentologic characteristics of these sediments has helped to resolve apparent discrepancies between fossil and strontium isotope ages. Hence, it is possible to show that the subsidence was active during early Miocene times. On La Désirade (Guadeloupe France), the Neogene to Quaternary carbonate cover has been dated by microfossils and some U/Th-ages. Disagreements subsisted in the paleontological ages of the formations. Strontium isotope ratios ranging from 0.709047 to 0.709076 showed the Limestone Table of La Désirade to range from an Early Pliocene to Late Pliocene/early Pleistocene age. A very late Miocene age (87Sr/86Sr =0.709013) can be determined to the Detrital Offshore Limestone. The flat volcanic basement had to be eroded by wave-action during a long-term stable relative sea-level. Sediments of the Table Limestone on La Désirade show both low-stand and high-stand facies that encroach on the igneous basement, implying deposition during a major phase of subsidence creating accommodation space. Subsidence is followed by tectonic uplift documented by fringing reefs and beach rocks that young from the top of the Table Limestone (180 m) towards the present coastline. Strontium isotope ratios from two different fringing reefs (0.707172 and 0.709145) and from a beach rock (0.709163) allow tentative dating, (125ky, ~ 400ky, 945ky) and indicate an uplift rate of about 5cm/ky for this time period of La Désirade Island. The documented subsidence and uplift history calls for a new model of tectonic evolution of the area.
Resumo:
This Technical Report presents a tentative protocol used to assess the viability of powersupply systems. The viability of power-supply systems can be assessed by looking at the production factors (e.g. paid labor, power capacity, fossil-fuels) – needed for the system to operate and maintain itself – in relation to the internal constraints set by the energetic metabolism of societies. In fact, by using this protocol it becomes possible to link assessments of technical coefficients performed at the level of the power-supply systems with assessments of benchmark values performed at the societal level throughout the relevant different sectors. In particular, the example provided here in the case of France for the year 2009 makes it possible to see that in fact nuclear energy is not viable in terms of labor requirements (both direct and indirect inputs) as well as in terms of requirements of power capacity, especially when including reprocessing operations.
Resumo:
There are many factors that influence the day-ahead market bidding strategies of a generation company (GenCo) in the current energy market framework. Environmental policy issues have become more and more important for fossil-fuelled power plants and they have to be considered in their management, giving rise to emission limitations. This work allows to investigate the influence of both the allowances and emission reduction plan, and the incorporation of the derivatives medium-term commitments in the optimal generation bidding strategy to the day-ahead electricity market. Two different technologies have been considered: the coal thermal units, high-emission technology, and the combined cycle gas turbine units, low-emission technology. The Iberian Electricity Market and the Spanish National Emissions and Allocation Plans are the framework to deal with the environmental issues in the day-ahead market bidding strategies. To address emission limitations, some of the standard risk management methodologies developed for financial markets, such as Value-at-Risk (VaR) and Conditional Value-at-Risk (CVaR), have been extended. This study offers to electricity generation utilities a mathematical model to determinate the individual optimal generation bid to the wholesale electricity market, for each one of their generation units that maximizes the long-run profits of the utility abiding by the Iberian Electricity Market rules, the environmental restrictions set by the EU Emission Trading Scheme, as well as the restrictions set by the Spanish National Emissions Reduction Plan. The economic implications for a GenCo of including the environmental restrictions of these National Plans are analyzed and the most remarkable results will be presented.
Resumo:
CO2 emissions induced by human activities are the major cause of climate change; hence, strong environmental policy that limits the growing dependence on fossil fuel is indispensable. Tradable permits and environmental taxes are the usual tools used in CO2 reduction strategies. Such economic tools provide incentives to polluting industries to reduce their emissions through market signals. The aim of this work is to investigate the direct and indirect effects of an environmental tax on Spanish products and services. We apply an environmentally extended input-output (EIO) model to identify CO2 emission intensities of products and services and, accordingly, we estimate the tax proportional to these intensities. The short-term price effects are analyzed using an input-output price model. The effect of tax introduction on consumption prices and its influence on consumers’ welfare are determined. We also quantify the environmental impacts of such taxation in terms of the reduction in CO2 emissions. The results, based on the Spanish economy for the year 2007, show that sectors with relatively poor environmental profile are subjected to high environmental tax rates. And consequently, applying a CO2 tax on these sectors, increases production prices and induces a slight increase in consumer price index and a decrease in private welfare. The revenue from the tax could be used to counter balance the negative effects on social welfare and also to stimulate the increase of renewable energy shares in the most impacting sectors. Finally, our analysis highlights that the environmental and economic goals cannot be met at the same time with the environmental taxation and this shows the necessity of finding other (complementary or alternative) measures to ensure both the economic and ecological efficiencies. Keywords: CO2 emissions; environmental tax; input-output model, effects of environmental taxation.
Resumo:
The family Acrochordiceratidae Arthaber, 1911 ranges in age from latest Spathian to the middle/late Anisian boundary, and it represents a major component of ammonoid faunas during that time. The middle Anisian genus Acrochordiceras Hyatt, 1877 is the most widespread taxon of the family and occurs abundantly worldwide within the low paleolatitude belt. However, there is a profusion of species names available for Acrochordiceras. This excessive diversity at the species level essentially results from the fact that sufficiently large samples were not available, thus leading to a typological approach to its taxonomy. Based on new extensive collections obtained from the Anisian (Middle Triassic) Fossil Hill Member (Star Peak Group, north-west Nevada) for which a high resolution biostratigraphic frame is available, the taxonomy and biostratigraphy of the genus Acrochordiceras Hyatt, 1877 is herein revised with respect to its intra-specific variation. Morphological and biometric studies (c. 550 bedrock-controlled specimens were measured) show that only one species occurs in each stratigraphic level. Continuous ranges of intra-specific variation of studied specimens enable us to synonymize Haydenites Diener, 1907, Silesiacrochordiceras Diener, 1916 and Epacrochordiceras Spath, 1934 with Acrochordiceras Hyatt, 1877. Three stratigraphically successive species are herein recognized in the low paleolatitude middle Anisian faunas from Nevada: A. hatschekii (Diener, 1907), A. hyatti Meek, 1877 and A. carolinae Mojsisovics, 1882. Moreover, an assessment of intra-specific variation of the adult size range does not support recognition of a dimorphic pair (Acrochordiceras and Epacrochordiceras) as previously suggested by other workers (Epacrochordiceras is the compressed and weakly ornamented end-member variant of Acrochordiceras). The successive middle Anisian species of Acrochordiceras form an anagenetic lineage characterized by increasing involution, adult size and intra-specific variation. This taxonomic revision based on new bedrock-controlled collections is thus an important prerequisite before studying the evolution of the group.
Resumo:
L’estudi analitza detalladament les energies que s’utilitzen actualment a la població d’Alinyà (Lleida, Catalunya, Espanya). Les energies més utilitzades amb fins calorífics provenen d’energies fòssils (95,3%). Aquest tipus d’energia, des de un punt de vista econòmic, és inviable donat l’augment continuat dels preus d’aquest tipus de combustibles. A més a més el petroli ha arribat al peak oil. Tenint en compte la delicada situació que viuen actualment els combustibles fòssils, en particular el petroli, fa pensar que el futur està encaminat a produir energia a partir d’altres fonts. Una bona opció és començar a utilitzar biomassa com a font energètica. La zona d’estudi presenta un stock de biomassa 8,4 vegades superior a la que es necessitaria a Alinyà per produir calor i ACS a totes les llars. Per això, en aquest estudi, s’estimen possibles escenaris on es podria aplicar la biomassa que es produeix a la Vall d’Alinyà. S’estima que les calderes individuals serien l’escenari més viable, ja que tècnicament són eficients i s’adeqüen a les característiques de les llars d’aquesta població. Posteriorment, es realitza un estudi de les emissions de CO2 i s’observa que, si s’utilitzés biomassa com a font energètica a Alinyà ,es reduirien 11,3 vegades (91,11%) les emissions de CO2.
Resumo:
We sequenced 2167 base pairs (bp) of mitochondrial DNA cytochrome b and 16S, and 1390 bp of nuclear genes BRCA1 and ApoB in shrews taxa (Eulipotyphla, family Soricidae). The aim was to study the relationships at higher taxonomic levels within this family, and in particular the position of difficult clades such as Anourosorex and Myosorex. The data confirmed two monophyletic subfamilies, Soricinae and Crocidurinae. In the former, the tribes Anourosoricini, Blarinini, Nectogalini, Notiosoricini, and Soricini were supported. The latter was formed by the tribes Myosoricini and Crocidurini. The genus Suncus appeared to be paraphyletic and included Sylvisorex. We further suggest a biogeographical hypothesis, which shows that North America was colonized by three independent lineages of Soricinae during middle Miocene. Our hypothesis is congruent with the first fossil records for these taxa. Using molecular dating, the first exchanges between Africa and Eurasia occurred during the middle Miocene. The last one took place in the Late Miocene, with the dispersion of the genus Crocidura through the old world.
Resumo:
A aquest estudi s'ha analitzat si és viable l'autosuficiència energètica en base a un estudi pilot al nucli rural d'Alinyà aprofitant els recursos naturals de la zona. S'ha realitzat un estudi del consum energètic de la població i s'ha comparat amb el potencial de producció energètica dels recursos renovables locals incloent energia provinent de la biomassa i aprofitada en calderes individuals per a cada habitatge, energia solar en teulades i energia hidroelèctrica a partir de centrals minihidràuliques restaurades ja existents. També s’ha realitzat un anàlisi per detectar possibles factors d’ineficiència energètica i a partir d’aquí, proposar una sèrie de mesures per corregir aquesta. S'han comptabilitzat les emissions de CO2 derivades del consum energètic i les proporcions que representa cada tipus de font energètica sobre el total del nucli. També s'ha establert una comparativa del consum mitjà per habitant i any entre la població i Catalunya; el consum a Alinyà és d'1,46 Tep's, mentre que el de Catalunya és d'1,7 Tep's, el nostre estudi no contempla la mobilitat, si se li resta aquest vector a la mitjana de Catalunya veiem que és de 0,9 Tep's, per tant, hi observem un major consum energètic. El 76% del consum d'Alinyà prové dels combustibles fòssils, concretament del gasoil, el nucli té una forta dependència respecte a aquesta energia, que a més a més representa el 86% (56T CO2 eq.) de les emissions totals de CO2. Per finalitzar, s'ha demostrat que és possible assolir l'autosuficiència energètica mitjançant l'implantació d'una combinació d'estratègies, viables en tots els aspectes; tant tècnics com socioeconòmics. Abastint el poble d'energia a un menor cost econòmic i amb un estil de vida més respectuós amb el medi ambient.
Resumo:
El present projecte s'ha dut a terme a l'American Museum of Natural History (AMNH, New York) entre el 31 de Desembre de 2010 i el 30 de Desembre de 2012. L'objectiu del projecte era elucidar la història evolutiva de la mà humana: traçar els canvis evolutius en la seva forma i proporcions que van propiciar la seva estructura moderna que permet als humans manipular amb precisió. El treball realitzat ha inclòs recol•lecció de dades i anàlisis, redacció de resultats i formació en mètodes analítics específics. Durant aquest temps, l'autor a completat la seva de base de dades existent en mesures lineals de la mà a hominoides. També s'han agafat dades del peu; d'aquesta forma ara mateix es compta amb una base de dades amb més de 500 individus, amb més de 200 mesures per cada un. També s'han agafat dades en tres imensions utilitzant un làser escàner. S'han après tècniques de morfometria geomètrica 3D directament dels pioners al camp a l'AMNH. Com a resultat d'aquesta feina s'han produït 10 resums (publicats a congressos internacionals) i 9 manuscrits (molts d'ells ja publicats a revistes internacionals) amb resultats de gran rellevància: La mà humana posseeix unes proporcions relativament primitives, que són més similars a les proporciones que tenien els hominoides fòssils del Miocè que no pas a la dels grans antropomorfs actuals. Els darrers tenen unes mans allargades amb un polzes molt curts que reflexen l'ús de la mà com a eina de suspensió sota les branques. En canvi, els hominoides del Miocè tenien unes mans relativament curtes amb un polze llarg que feien servir per estabilitzar el seu pes quan caminaven per sobre de les branques. Una vegada els primers homínids van aparèixer al final del Miocè (fa uns 6 Ma) i van començar a fer servir el bipedisme com a mitjà més comú de locomoció, les seves mans van ser "alliberades" de les seves funcions locomotores. La selecció natural—ara només treballant en la manipulació—va convertir les proporcions ja existents de la mà d'aquests primats en l'òrgan manipulatori que representa la mà humana avui dia.
Resumo:
Estudi realitzat a partir d’una estada al Kimmel Center for Archaeological Research, Israel, entre 2010 i 2012. Els fitòlits són un dels components principals dels sediments arqueològics. Són relativament estables i menys propensos a la degradació biològica que altres restes vegetals, però també poden ser afectats per la diagènesis. Per entendre com la diagènesis afecta als fitòlits hem desenvolupat una aproximació experimental utilitzant solucions alcalines per determinar l’estabilitat individual de fitòlits fòssils i moderns. L’experimentació ha estat completada amb un estudi de camp a Izbet Sartah. Els resultats mostren com la diagènesis canvia la composició dels conjunts de fitòlits, i per tant afecta la interpretació arqueològica. Conseqüentment, hem desenvolupat un mètode per determinar l’estat de preservació dels fitòlits en els jaciments arqueològics. L’experimentació mostra com els fitòlits moderns són més solubles que els fitòlits fòssils. Tant els fitòlits fòssils com els moderns són menys estables si són cremats. No totes les morfologies es preserven igual, indicant així que hi ha unes morfologies més estables que unes altres. Els fitòlits amb decoracions delicades, especialment aquells formats a la inflorescència de gramínies, són més propensos a la dissolució que els de les fulles. L’avaluació de l’estat de preservació dels fitòlits en jaciments arqueològics es pot realitzar utilitzant un conjunt de tècniques com ara: l’Index de Variació de Fitòlits, el mètode de dissolució ràpida, la identificació de morfologies delicades i la utilització del FTIR. Proposem que la diagènesis dels fitòlits depèn directament de la quantitat inicial de fitòlits en els sediments, la velocitat de sedimentació, i la presència o absència de fitòlits i plantes modernes en l’àrea estudiada. Els resultats d’aquesta investigació han estat publicats en dos articles afegits al final de l’informe (Cabanes et al., 2011 i Cabanes et al., in press), presentats en congressos internacionals i utilitzats indirectament en altres investigacions.
Resumo:
Shrews of the genus Sorex are characterized by a Holarctic distribution, and relationships among extant taxa have never been fully resolved. Phylogenies have been proposed based on morphological, karyological, and biochemical comparisons, but these analyses often produced controversial and contradictory results. Phylogenetic analyses of partial mitochondrial cytochrome b gene sequences (1011 bp) were used to examine the relationships among 27 Sorex species. The molecular data suggest that Sorex comprises two major monophyletic lineages, one restricted mostly to the New World and one with a primarily Palearctic distribution. Furthermore, several sister-species relationships are revealed by the analysis. Based on the split between the Soricinae and Crocidurinae subfamilies, we used a 95% confidence interval for both the calibration of a molecular clock and the subsequent calculation of major diversification events within the genus Sorex. Our analysis does not support an unambiguous acceleration of the molecular clock in shrews, the estimated rate being similar to other estimates of mammalian mitochondrial clocks. In addition, the data presented here indicate that estimates from the fossil record greatly underestimate divergence dates among Sorex taxa.
Resumo:
A elevada dependência dos combustíveis fósseis é uma das principais dificuldades sentidas no actual sistema energético de Cabo Verde. O preço dos combustíveis constitui um peso significativo, representando cerca de 70%, da estrutura de custos do preço de energia eléctrica. Com este trabalho, pretende-se analisar o impacto das energias renováveis no sistema energético e na economia de Cabo Verde, destacando a sua contribuição para a formação do PIB, no Preço, na Balança de Pagamentos, no Emprego, e no Serviço da Dívida, e estabelecer uma comparação com as ilhas da Macaronésia, em particular a Região Autónoma dos Açores. Contribuindo assim, para a discussão que poderá demonstrar que o potencial de renováveis por explorar, trará benefícios económicos para o país, pois a expectativa é superar os 50% de taxa de penetração de Energias Renováveis na produção de electricidade em Cabo Verde até 2020. Prevê-se que o consumo de electricidade que em 2010 era de 335 MWh, duplique até o ano de 2020, atingindo os 670 GWh. Segundo estudos efectuados, o país possui um potencial estimado de 2.600 MW de Energias Renováveis, tendo sido analisados mais de 650 MW em projectos concretos com custos de produção possivelmente inferiores aos dos combustíveis fósseis. Cabo Verde goza de boas condições para o aproveitamento de Energias Renováveis, mas a contribuição desse potencial, sobretudo eólica e solar, continuam muito limitado, pelo que o país deverá apostar no incremento da utilização dessas formas de energia para reduzir a dependência externa em matéria de energia. The high dependence on fossil fuels is one of the main difficulties in the current energy system in Cape Verde. The price of fuel is a significant, accounting for about 70%, and the cost structure of the price of electricity. With this work, seeks to analyze the impact of renewable energy in the energy system and the economy of Cape Verde, highlighting their contribution to the formation of BIP, in the Balance of Payments, in Employment, and the Service of Debt, and to draw a comparison with the islands of Macaronésia, in particular the Autonomous Region of Azores. Thus contributing to the discussion that may show that the potential of renewable energy by exploring will bring economic benefits to the country, because the expectation is to exceed the 50% penetration rate of Renewable Energy in the production of electricity in Cape Verde until 2020. It is estimated that the consumption of electricity in 2010 was 335 MWh, will double by the year 2020, reaching the 670 GWh. According to studies carried out, the country has an estimated potential of 2,600 MW of Renewable Energy, having been analyzed more than 650 MW in concrete projects with production costs possibly less than the fossil fuels. Cape Verde enjoys good conditions for the use of renewable energy, but the contribution of this potential, especially wind and solar, are still very limited, so that the country should invest in increasing the use of these forms of energy to reduce the dependence on foreign sources of energy.
Resumo:
Directed evolution of life through millions of years, such as increasing adult body size, is one of the most intriguing patterns displayed by fossil lineages. Processes and causes of such evolutionary trends are still poorly understood. Ammonoids (externally shelled marine cephalopods) are well known to have experienced repetitive morphological evolutionary trends of their adult size, shell geometry and ornamentation. This study analyses the evolutionary trends of the family Acrochordiceratidae Arthaber, 1911 from the Early to Middle Triassic (251228 Ma). Exceptionally large and bed-rock-controlled collections of this ammonoid family were obtained from strata of Anisian age (Middle Triassic) in north-west Nevada and north-east British Columbia. They enable quantitative and statistical analyses of its morphological evolutionary trends. This study demonstrates that the monophyletic clade Acrochordiceratidae underwent the classical evolute to involute evolutionary trend (i.e. increasing coiling of the shell), an increase in its shell adult size (conch diameter) and an increase in the indentation of its shell suture shape. These evolutionary trends are statistically robust and seem more or less gradual. Furthermore, they are nonrandom with the sustained shift in the mean, the minimum and the maximum of studied shell characters. These results can be classically interpreted as being constrained by the persistence and common selection pressure on this mostly anagenetic lineage characterized by relatively moderate evolutionary rates. Increasing involution of ammonites is traditionally interpreted by increasing adaptation mostly in terms of improved hydrodynamics. However, this trend in ammonoid geometry can also be explained as a case of Copes rule (increasing adult body size) instead of functional explanation of coiling, because both shell diameter and shell involution are two possible paths for ammonoids to accommodate size increase.
Resumo:
Strepsirhines comprise 10 living or recently extinct families, ≥50% of extant primate families. Their phylogenetic relationships have been intensively studied, but common topologies have only recently emerged; e.g. all recent reconstructions link the Lepilemuridae and Cheirogaleidae. The position of the indriids, however, remains uncertain, and molecular studies have placed them as the sister to every clade except Daubentonia, the preferred sister group of morphologists. The node subtending Afro-Asian lorisids has been similarly elusive. We probed these phylogenetic inconsistencies using a test data set including 20 strepsirhine taxa and 2 outgroups represented by 3,543 mtDNA base pairs, and 43 selected morphological characters, subjecting the data to maximum parsimony, maximum likelihood and Bayesian inference analyses, and reconstructing topology and node ages jointly from the molecular data using relaxed molecular clock analyses. Our permutations yielded compatible but not identical evolutionary histories, and currently popular techniques seem unable to deal adequately with morphological data. We investigated the influence of morphological characters on tree topologies, and examined the effect of taxon sampling in two experiments: (1) we removed the molecular data only for 5 endangered Malagasy taxa to simulate 'extinction leaving a fossil record'; (2) we removed both the sequence and morphological data for these taxa. Topologies were affected more by the inclusion of morphological data only, indicating that palaeontological studies that involve inserting a partial morphological data set into a combined data matrix of extant species should be interpreted with caution. The gap of approximately 10 million years between the daubentoniid divergence and those of the other Malagasy families deserves more study. The apparently contemporaneous divergence of African and non-daubentoniid Malagasy families 40-30 million years ago may be related to regional plume-induced uplift followed by a global period of cooling and drying. © 2013 S. Karger AG, Basel.