963 resultados para Quaternary
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Proceedings of the 1" R.C.A.N.S. Congress, Lisboa, October 1992
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Proceedings of tile 1" R.C.A.N.S. Congress, Lisboa, October 1992
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The main goal of the present work is the use of mineralogical data corresponding to sediment fine fractions (silt and clay) of Quaternary littoral deposits for the definition of a more detailed vertical zonography and to discriminate the most significant morphoclimatic changes concerned with sediment source areas and sediment deposition areas. The analysis of the available mineralogical data reveals a vertical evolution of the mineral composition. The following aspects deserve particular reference: 1) fine fractions (<38 nm) are composed of quartz and phyllosilicates associated to feldspars, prevailing over other minerals; however in certain sections iron hydroxides and evaporitic minerals occur in significant amounts; 2) clay fractions (<2 nm) show a general prevalence of illite associated with kaolinite and oscillations, in relative terms, of kaolinite and illite contents. Qualitative and quantitative lateral and vertical variations of clay and non clay minerals allow the discrimination of sedimentary sequences and the establishment of the ritmicity and periodicity of the morphoclimatic Quaternary episodes that occurred in the Cortegaça and Maceda beaches. To each one of the sedimentary sequences corresponds, in a first stage, a littoral environment that increasingly became more continental. Climate would be mild to cold, sometimes with humidity - aridity oscillations. Warmer and moister episodes alternated with cooler and dryer ones.
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The sub-fossil fauna from the Late Quaternary marine deposits of Santa Maria is made of more than 50 species of gastropods and bivalves, 19 of them collected recently and for the first time in the northern coast of the island (Lagoinhas Bay). The sub-fossil shells are found in deposits of beach sands, situated 2-3 meters above the present low tide. The carbonated sands from the basal part of the succession yield an autochthonous association of borers dominated by the bivalve Myoforceps aristata (Dillwin, 1817). Upwards, the marine sands contain concentrations of beach drift shells, including well-preserved supratidal and intertidal gastropods, among them a large number of Rissoidae. The bivalve fauna is dominated by disarticulated valves of Ervilia castanea (Montagu, 1803), a small infaunal coloniser of mobile sandy substrates. The composition of the fauna is made essentially of West European species, many of them common to the West Coast of Portugal. However, a few "warm guests" with West African or Caribbean affinities were also found, suggesting a close relation with some of the "Tyrrhenian" warm associations found in the Western Mediterranean.
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During a recent field work on the southern coast of the island of Santa Maria (Azores) a bulk sample of 37 shells and 25 fragments of Leptaxis vetusta was assembled from Late Pleistocene and Holocene slope deposits outcropping in the area. These specimens are the first of this rare subfossil species to be mentioned since the original descriptions of Arthur Morelet and Henri Drouet (1857). The purposes of our paper are a systematic and biometric description of L. vestuta. For the first time, the original type: locality was localized with accuracy over the southern downslopes of Pico do Facho, between Figueiral and Prainha. The subfossil specimens were collected in slope deposits and detritic fans, overlying a fossiliferous marine deposit situated over the 2-3 m abrasion platform of Praia and Prainha bay. The age and factors associated to the extinction of this species are discussed, including the destruction of the original laurel cover and the colonization by Otala lactea (Muller, 1774), a continental helicid introduced and widespread in Santa Maria.
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INTRODUCTION : In this study, clinical-laboratory and epidemiological characteristics are described for a group of 700 individuals with HIV (human immunodeficiency virus)/AIDS (acquired immunodeficiency syndrome) in the ART (antiretroviral therapy) era at a teaching hospital that provides a quaternary level of care, with an emphasis on opportunistic infections (OIs), co-infections and immune profile. METHODS : A retrospective cross-sectional study of AIDS cases was conducted from 1998 to 2008 by reviewing medical records from the Base Hospital/FUNFARME (Fundação Faculdade Regional de Medicina), São José do Rio Preto, São Paulo, Brazil. RESULTS: The individuals were 14 to 75 years of age, and 458 were males. Heterosexuals accounted for 31.1% of all patients. Eighty-three percent were on ART, and 33.8% of those presented difficulties with treatment adherence. OIs were analyzed from medical records, and Pneumocystis jiroveci pneumonia was the most prevalent, regardless of the LTCD4+ (TCD4+ Lymphocytes) levels. Individuals whose viral loads were ≥10,000 showed a 90% greater chance of neurotoxoplasmosis. For P. jiroveci pneumonia, neurotoxoplasmosis, esophageal candidiasis, pulmonary tuberculosis and neurocryptococcosis, the chances of infection were higher among patients with LTCD4+ levels below 200 cells/mm3. HIV/hepatitis C virus (HCV) and HIV/hepatitis B virus (HBV) co-infections were significantly associated with death. CONCLUSIONS : OIs remain frequent in the ART era even in populations where the access to medical care is considered satisfactory.
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El objetivo de este trabajo es caracterizar la respuesta de P. putida frente a condiciones ambientales adversas dadas por la presencia del detergente catiónico tetradeciltrimetilamonio (TDTMA). El objetivo final que se persigue es el de utilizar este microorganismo como vehículo en procesos de biorremediación. El proyecto comprende aspectos relacionados con la degradación y con la respuesta adaptativa que le permiten a P. putida tolerar altas concentraciones del biocida. La degradación de TDTMA por P. putida involucra una actividad monooxigenasa, que produce trimetilamina (TMA) y tetradecilalcanal. Parte de la TMA producida es demetilada, por una TMAdehidrogenasa (TMADH), e utilizada por la bacteria como fuente de nitrógeno y parte es acumulada intracelularmente, inhibiendo el crecimiento bacteriano. Considerando la importancia de las oxigenasas y dehidrogenasas en la transformación química de compuestos recalcitrantes, se identificarán los genes responsables de la actividad monooxigenasa y de la TMADH, se caracterizarán las enzimas, lo que permitirá conocer, además, datos evolutivos de las mismas. Teniendo en cuenta que la acumulación intracelular TMA conduce a la degradación parcial del detergente, efecto contrarrestado por la adición de aluminio (Al), se investigarán si otros factores nutricionales participan en el control de la degradación de TDMA por P. putida. Se investigará si el regulador global NtrC, que se activa en respuesta a limitación de nitrógeno, participa en el metabolismo de TDTMA. Se prevé construir mutantes en los genes que codifican para monoxigenasa y TMADH y analizar la respuesta de estas cepas frente al estrés ocasionado por TDTMA y Al. En este proyecto se postula además que los cambios a nivel de fosfolípidos (PL) de membrana son una estrategia de P. putida para sobrevivir en presencia del TDTMA. Para concluir si fosfatidilglicerol es el principal responsable de la adaptación de P. putida frente al estrés ocasionado por TDTMA, se pretenden obtener mutantes afectadas en la biosíntesis de novo de PL, particularmente en cardiolipina sintasa. Paralelamente se estudiará si fosfolipasa D participa en la respuesta, lo que permitirá asignar un rol a esta enzima en procesos de señalización análogos a los que ocurren en organismos eucariotas. En presencia de TDTMA y Al, P. putida responde aumentando el contenido de fosfatidilcolina y posiblemente este PL actúe como un reservorio temporario del ión. Identificar en P. putida los genes que codifican para las enzimas responsables de su biosíntesis, particularmente fosfatidilcolina sintasa y/o fosfolípido N-metiltranferasa, conducirá a conocer el mecanismo por el cual fosfatidilcolina estaría involucrada en la respuesta a Al.
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no.6 (1979)
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We used mitochondrial cyt b sequences to investigate the phylogenetic relationships of Crocidura russula (sensu lato) populations across the Strait of Gibraltar, western Europe, Maghreb, and the Mediterranean and Atlantic islands. This revealed very low genetic divergence between European and Moroccan populations. The application of a molecular clock previously calibrated for shrews suggested that the separation of European from Moroccan lineages occurred less than 60 000 bp, which is at least 5 million years (Myr) after the reopening of the Strait of Gibraltar. This means that an overwater dispersal event was responsible for the observed phylogeographical structure. In contrast, genetic analyses revealed that Moroccan populations were highly distinct from Tunisian ones. According to the molecular clock, these populations separated about 2.2 million years ago (Ma), a time marked by sharp alternations of dry and humid climates in the Maghreb. The populations of the Mediterranean islands Ibiza, Pantelleria, and Sardinia were founded from Tunisian populations by overwater dispersal. In conclusion, overwater dispersal across the Strait of Gibraltar, probably assisted by humans, is possible for small terrestrial vertebrates. Moreover, as in Europe, Quaternary climatic fluctuations had a major effect on the phylogeographical structure of the Maghreb biota.
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Ammonium salt derivatives of natural allylphenols were synthesized with the purpose of obtaining potential peripheral analgesics. These drugs, by virtue of their physicochemical properties, would not be able to cross the blood brain barrier. Their inability to enter into the central nervous system (CNS) should prevent several adverse effects observed with classical opiate analgesics (Ferreira et al., 1984). Eugenol (1) O-methyleugenol (5) and safrole (9) were submitted to nitration, reduction and permethylation, leading to the ammonium salts 4, 8 and 12. Another strategy applied to eugenol (1), consisting in its conversion to a glycidic ether (13), opening the epoxide ring with secondary amines and methylation, led to the ammonium salts 16 and 17. All these ammonium salts showed significant peripheral analgesic action, in modified version of the Randall-Sellito test (Ferreira et al. 1978), at non-lethal doses. The ammonium salt 8 showed an activity comparable to that of methylnalorphinium, the prototype of an ideal peripheral analgesic (Ferreira et al., 1984).
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The location and timing of domestication of the olive tree, a key crop in Early Mediterranean societies, remain hotly debated. Here, we unravel the history of wild olives (oleasters), and then infer the primary origins of the domesticated olive. Phylogeography and Bayesian molecular dating analyses based on plastid genome profiling of 1263 oleasters and 534 cultivated genotypes reveal three main lineages of pre-Quaternary origin. Regional hotspots of plastid diversity, species distribution modelling and macrofossils support the existence of three long-term refugia; namely the Near East (including Cyprus), the Aegean area and the Strait of Gibraltar. These ancestral wild gene pools have provided the essential foundations for cultivated olive breeding. Comparison of the geographical pattern of plastid diversity between wild and cultivated olives indicates the cradle of first domestication in the northern Levant followed by dispersals across the Mediterranean basin in parallel with the expansion of civilizations and human exchanges in this part of the world.
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A high-resolution three-dimensional (3-D) seismic reflection survey was conducted in Lake Geneva, near the city of Lausanne, Switzerland, as part of a project for developing such seismic techniques. Using a single 48-channel streamer, the 3-D site with an area of 1200 m x 600 m was surveyed in 10 days. A variety of complex geologic structures (e.g. thrusts, folds, channel-fill) up to similar to150 m below the water bottom were obtained with a 15 in.(3) water gun. The 3-D data allowed the construction of an accurate velocity model and the distinction of five major seismic facies within the Lower Freshwater Molasse (Aquitanian) and the Quaternary sedimentary units. Additionally, the Plateau Molasse (PM) and Subalpine Molasse (SM) erosional surface, "La Paudeze" thrust fault (PM-SM boundary) and the thickness of Quaternary sediments were accurately delineated in 3-D.
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Quaternary prevention aims to protect the patient or population against overmedicalisation. Quaternary prevention influences all the activities of family medicine by questioning the utility of primary prevention and early diagnosis, identifying the risks of creating new pathological entities and practicing a maximalist medicine. Family doctors can support quaternary prevention by focusing on their patients' priorities and the local resources of an efficient health system.
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The fate of European arctic-alpine species during Pleistocene climatic oscillations still remains debated. Did these cold-adapted species invade much of the continental steppe or did they remain restricted to warmer slopes of inner mountain massifs? To examine this question, we investigated the phylogeography of Gentiana nivalis, a typical European arctic-alpine plant species. Genome fingerprinting analyses revealed that four genetic pools are actually unevenly distributed across the continent. One cluster covers almost all mountain massifs as well as northern areas, and thus coincides with a scenario of past distribution covering a large part of the European glacial steppe. In contrast, the three other lineages are strongly restricted spatially to western, central, and eastern Alps, respectively, thus arguing towards a scenario of in situ glacial survival. The coexistence of lineages with such contrasting demographic histories in Europe challenges our classical view of refugia and corroborates several hypotheses of biogeographers from the twentieth century.