994 resultados para Ones de gravetat
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Mestrado em Gestão e Empreendedorismo
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From a paleontological point of view previous determinations for some specimens as Tetralophodon longirostris can be confirmed from Azambujeira (upper level), Valverde and Vale de Matança. A so far undescribed and rare D3 (from Azambujeira, middle level) has been studied. For the first time in Portugal a Gomphotherium angustidens transitional to «Tetralophodon» grandincisivus is reported (from Portas do Sol). Teeth from Lisbon formerly reported (in part) to T. longirostris are now ascribed to G. angustidens. The presence of T. longirostris at Vale de Matança excludes a Pliocene age for Marateca Formation. This and some other evidence clearly points out towards an early Vallesian age. G. angustidens transitional to T. grandincisivus found at Portas do Sol is enough to ascribe this locality to the latest Middle Miocene or earliest Upper Miocene. Therefore it is possible to correlate overlying Santarém limestones to the Vallesian Cartaxo and Almoster ones which are better dated.
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A new locality rich in plant leaf impressions has been found in the northwestern part of Sado basin at Vale de Coelheiros (Grândola, Portugal). 1 The study of the material so far collected allowed us to identify: Salix lavateri BRAUN, 1851; Myrica sp., Zelkova zelkovaefolia (UNGER, 1843) BUZEK & KOTLABA, 1963 and Acer tricuspidatum BRONN, 1838. This association is closely comparable with other ones from several localities in Tagus basin, specially with Vallesian ones. Comparisons and biostratigraphical correlations are established.
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Glauconite K-Ar ages (6.88±0.4; 7.03±0.4 MY) confirm earlier reports to Upper Tortonian of silt beds near Morgadinho, Luz de Tavira and Tavira. Taking stratigraphical position and age into account it is possible now to correlate these beds with similar ones at Quelfes and Cacela (Formação de Cacela, lower member, ascribed to the upper part of N16 or to NI7 Blow's zone, Globorotalia humerosa - G. dutertrei; Tortonian to Messinian, according to the ostracod fauna). Limit between the above quoted zones is thus placed at about 7 MY. New K-Ar ages greatly improve the knowledge about Upper Miocene in eastern Algarve, and on regional tectonic evolution. This is particulary so in what concerns an intra-Tortonian phase.
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In the southern part of Tagus basin, North of paleozoic rocks of Valverde-Senhor das Chagas (near Alcácer do Sal) horst, a marine transgression has been recognized, Upper Serravallian, and maybe Lower Tortonian in age. There are no earlier marine deposits, and no younger ones are known either. Paleozoic behaved as a barrier separating two basins, distinct at least since Middle Miocene until Upper Pleistocene. Until now, both were regarded as a single entity, the so-called «Sado basin» Southwards (Alvalade basin) there has been a single transgression. It was assummed that it was the same one as the former. Indeed it is not definitely so. Later transgression accounts for Esbarrondadoiro Formation, whose deposits have been ascribed to Tortonian or even to Middle Miocene. However they are Upper Messinian to Lower Zanclean. Esbarrondadoiro Formation is younger than Lower Member of Cacela Formation in Algarve and, with even stronger reason, than the upper-most well dated marine levels in Tagus basin. Age of Miocene units dealt with here has been based on small mammals found in marine sands.
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Improved bromoform concentration as developped at CEPUNL allowed better recovery of small mammals'teeth. At Universidade Católica and Avenida do Uruguay 19 taxa (and a further one with doubt) were recognized. Some are new for the level and for Tagus basin: Lagopsis cadeoti and Melissiodon dominans (1st reference for the genus); Glirudinus modestus (formerly under another name); Armantomys (1st reference for this level); Peridyromys murinus (referred before under another name); Microdyromys legidensis (1st ref. of gen. and sp. for this level); and Heteroxerus rubricati, formerly reported to other species of the same genus. Both localities share the same position viz marine levels under and above. This allows us to correlate them with NS or N6 Blow's zones. Both are distinctly younger-than glauconite in underlying beds about 21 MY old (K-Ar). Small mammals point out to MN3a Neogene subunit. Fauna is much alike Lower Burdigalian ones in Spain, France, Germany and Austria. Terrestrial, maybe steppe forms predominate. Land environment was open, with scant plant cover but not devoid of trees. Peridyromys murinus numerical importance and other data suggest a not so warm climate in correspondance to a minimum temperature event. This is corroborated by associated marine fish fauna entirely without warm water stenotherm species, and by paleobotanical/palynological data. Results are in close agreement with Central Northern Spain. The localities studied here are even more interesting as direct correlations between marine and continental stratigraphical scales are possible.
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Mestrado em Controlo de Gestão e dos Negócios
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Miocene catfishes from Lisbon are dealt with. Two distinct sets of pectoral and dorsal pterygiophores are described. That from the Langhian V-b is referred to Arius sp. probably close to A. heudeloti. Another ser from the uppermost Burdigalian V-a may be ascribed to a bagrid, cf. Chrysichthys sp., identified for the first time in this region. The catfish and Lates association is sctrikingly similar to African, nilotic or sudanian ones as far as freshwaters are concerned. In marine, coastal environments, stenotherm warm-water forms (Polynemids, large barracudas and several sharks) indicate, as a model, faunas like chose from Cape Verde to northern Angola. There is some gradation for brackish waters (fig. 1). Catfishes and Lates probably migrated into the Iberian Peninsule in the lower Miocene. They are unknown after Langhian V-b except for a reappearance of Arius in the middle Tortonian VII-b. Decreasing temperatures and aridity account for local extinction at least in freshwaters. Expansion of these fishes have been made easier owing to the displacement of land masses chat narrowed or closed the marine waterway between Europe and Africa. Salinity tolerance is not necessarily the sole explanation for migration. Catfishes plus Lates associations colonized inland waters from both sides of the Paleomediterranean. Local extinction may have weighed more in the development of modern distribution patterns than migration.
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Beaver only had been found in Portugal in a Chalcolithic locality, the Vila Nova de S. Pedro castrum. It has now been identified in the Upper Paleolithic (Solutrean) from Gruta do Caldeirão, near Tomar. The species has been found recently at «Gruta do Almonda»; 4 teeth were collected in bed C, older than a Solutrean sequence (see Anexo for details). The species seems to have been rare, as it was also the case with portuguese Miocene Castoridae Enroxenomys minutus and Chalicomys jaegeri. If account is taken of the presence in the Middle Ages until Castille of words meaning beaver (relared to the popular latin Fiber/Biber), it is obvious that these animais still existed then. Such nouns were largely predominant over rhe rather erudite latin (greek deríved) words as Castor,-óris and derived ones, as it could be expected. This allowed us to recognize that veiro should be the corresponding word with Fiber affinities in archaic portuguese. It was previously supposed to mean only expensive furs then imported into Portugal. Indeed it was also a zoonym. Anywày, beaver should be scarce by XIIIth century since it is not included in the quite detailed price list imposed by the «Lei da Almotaçaria» from December 26, 1253 (see Quadro II). Toponyms in veiro and derived words (fig. 2; Quadro III) (plural, feminines, diminutives, inhabited places) give a resrrictive view of rhe Middle Age distribution. Some of them are certainly older than Portugal itself (firsr half of XIlth cenrury); others existed by the XIVth century bur were probably older. Some rare toponyms seem to be derived from the erudite latin Castor,-óris. Nothing suggests that these words were still in use as zoonyms during the Middle Ages. All toponyms are located in regions near rivers and other freshwaters ecologically suitable for beavers, so we can approximately retrace its former, Middle Age disrribution in Portugal (fig. 2; Quadro III). Most of them are locared in the Center-West and Northwest of Portugal, with a suitable c1imate (rainfall in general over 800 mílimerers per year); the only sure geographical exception is Veiros, in Alto Alentejo province, in a region with comparable precipitations and less dry climate conditions than mosr of the territories South of rhe Tagus. There are less and less of these toponyms towards rhe South and the inner part of the country, and they are enrirely lacking in all drier regions from Trás-os-Montes, Beira, Alentejo beyond Tagus' basin, and in Algarve. Nothing suggests beavers lived there, No post-medieval toponym is known, nor any reference after middle XVth century. No such locality was at, or close by to, any frontier. Hence the hypothesis of veiro (et al.} as meaning but points where expensive furs (supposedly known as veiros in general but without c1early saying from what animal they were obrained from) is to be discarded. During the Middle Ages, beaver discriburion concerned all the main river basins from Minho to Tagus ones. Quite rarefied in rhe XIIIth, the beavers may have disappeared from Portugal during the XVth century. Ecological requiremenrs restricted their former distriburion. Vulnerability to natural causes (i.e., severe drought) and to human pressure may have accounted heavily for this species' extinction. Last (1446) reference for Portugal known to us suggests the species was by then almost extinct.
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New radiocarbon measurements were obtained from middle and upper Paleolithic sites currently under research by the CEPUNL, in well defined stratigraphical situations. With other dates, they yield an approximative chronological global view. Measurement distribution in function of time does not seem to be an hazardous one. In the actual status of our knowledge, this distribution seems to fit in some assemblages: (a) 14000 to 15000 BP, Solutrean; (b) about 20 000 BP, Solutrean; (c) circa 25 000 BP, already Solutrean, and slightly older than 26 000 BP, still Mousterian; (d) between 29 000 and 31 000 BP, Mousterian. The persistance of Mousterian much later than its acknowledged upper limit at about 34 000 BP (and hence the survival of its neanderthalian authors) is demonstrated. For the first time it has been possible to ascertain the upper time limit of the marine 5-8 metres raised beach (Tyrrhenian III) at Serra da Arrábida, and also the age of archaeological sites without stone artifacts, or with uncharacteristic ones. The obtained measurements allow US to correlate localities and sedimentary units with last glaciation events. There seems to have been a distinct correlation between cave and shelter human occupation and events marked by the worsening of climate.
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Since its official public release, Android has captured the interest from companies, developers and the general audience. From that time up to now, this software platform has been constantly improved either in terms of features or supported hardware and, at the same time, extended to new types of devices different from the originally intended mobile ones. However, there is a feature that has not been explored yet - its real-time capabilities. This paper intends to explore this gap and provide a basis for discussion on the suitability of Android in order to be used in Open Real-Time environments. By analysing the software platform, with the main focus on the virtual machine and its underlying operating system environments, we are able to point out its current limitations and, therefore, provide a hint on different perspectives of directions in order to make Android suitable for these environments. It is our position that Android may provide a suitable architecture for real-time embedded systems, but the real-time community should address its limitations in a joint effort at all of the platform layers.
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Mobile applications are becoming increasingly more complex and making heavier demands on local system resources. Moreover, mobile systems are nowadays more open, allowing users to add more and more applications, including third-party developed ones. In this perspective, it is increasingly expected that users will want to execute in their devices applications which supersede currently available resources. It is therefore important to provide frameworks which allow applications to benefit from resources available on other nodes, capable of migrating some or all of its services to other nodes, depending on the user needs. These requirements are even more stringent when users want to execute Quality of Service (QoS) aware applications, such as voice or video. The required resources to guarantee the QoS levels demanded by an application can vary with time, and consequently, applications should be able to reconfigure themselves. This paper proposes a QoS-aware service-based framework able to support distributed, migration-capable, QoS-enabled applications on top of the Android Operating system.
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The aim of this report is to highlight the importance of foresight exercises as a necessary tool to help the decision makers, allowing through projections and identification of the main trends, the identification of the key variables of the process and which ones may have more influence in the process of evolution of societies. It will be presented some examples of prospective methods and also scenarios construction. One example is the European project WORKS (Work organization restructuring in the knowledge society) that pretend to built a set of scenarios about the possible evolution of work in Europe in a short, medium and long term, stressing the key variables that may have an important role in the process and their interconnections. Another exemple is the report ‘Future skill needs in Europe’ prepared in 2008 by Cedefop, that presents data about the future development of employment by industry, occupation and qualification by 2015.
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Dissertação apresentada na Universidade do Minho com vista à obtenção do grau de Doutor em Tecnologias e Sistemas de Informação (Engenharia e Gestão de Sistemas de Informação)
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Dissertação para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Vias de Comunicação e Transportes