957 resultados para Acer palaeosaccharinum


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25 datasets (13 fossil leaf and pollen assemblages, 12 quantitative palaeoclimatic datasets) are provided in order to analyse Early Miocene palaeoclimate in Kazakhstan. The rich fossil record in Kazakhstan documents that during the Oligocene and Early Miocene this area in Central Eurasia was densely forested with warm-temperate deciduous trees and shrubs of the so-called "Turgayan flora". 29 fossil floras from 13 localities have been selected for a quantitative analysis of the Aquitanian (early Early Miocene) climate situation in Kazakhstan. The assessed mean annual temperatures generally place around 15 °C, while values of mean annual precipitation are of about 1000 mm. In combination with several other climate parameters estimated (temperatures of warmest and coldest months, precipitation rates of wettest, driest and warmest months), these data reflect uniform climatic conditions over several thousands of square kilometres. Data of temperature parameters show slight spatial differentiations, with generally cooler mean annual temperatures and higher seasonality (i.e. warmer summers and colder winters) in the north-eastern part of the study area compared with the south-western area around Lake Aral. As compared with palaeoclimate estimates for the European and East Asian Aquitanian, the central part of the Eurasian continent reveals evident signals of higher seasonality and slightly increased continentality.

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The effect of increasing population density on the formation of pits, their size and spatial distribution, and on levels of mortality was examined in the antlion Myrmeleon acer Walker. Antlions were kept at densities ranging from 0.4 to 12.8 individuals per 100 cm(2). The distribution of pits was regular or uniform across all densities, but antlions constructed proportionally fewer and smaller pits as density increased. Mortality through cannibalism was very low and only occurred at densities greater than five individuals per 100 cm(2). Antlions in artificially crowded situations frequently relocated their pits and when more space became available, individuals became more dispersed with time. Redistribution of this species results from active avoidance of other antlions and sand throwing associated with pit construction and maintenance, rather than any attempt to optimise prey capture per se.

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In the last years, a rising trend of pollen allergies in urban areas has been attributed to atmospheric pollution. In this work, we investigated the effects of SO2 and NO2 on the protein content, allergenicity, and germination rate of Acer negundo pollen. A novel environmental chamber was assembled to exposure pollen samples with SO2 or NO2 at two different levels: just below and two times the atmospheric hour-limit value acceptable for human health protection in Europe. Results showed that protein content was lower in SO2- exposed pollen samples and slightly higher in NO2-exposed pollen compared to the control sample. No different polypeptide profiles were revealed by SDSPAGE between exposed and nonexposed pollen, but the immunodetection assays indicated higher IgE recognition by all sera of sensitized patients to Acer negundo pollen extracts in all exposed samples in comparison to the nonexposed samples. A decrease in the germination rate of exposed in contrast to nonexposed pollen was verified, which was more pronounced for NO2-exposed samples. Our results indicated that in urban areas, concentrations of SO2 and NO2 below the limits established for human protection can indirectly aggravate pollen allergy on predisposed individuals and affect plant reproduction.

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Esta investigación representa una contribución a la literatura sobre el análisis retrospectivo de las fusiones. Su principal objetivo es la evaluación del impacto de la fusión entre Acer y Gateway, concretada a mediados de octubre de 2007 y que permitió a estas dos firmas convertirse en el tercer proveedor mundial de ordenadores personales. En particular, se examinan los efectos que durante el período previo e inmediatamente posterior a la fusión se produjeron sobre los precios de los productos. Para ello, se aplica el método de diferencias-endiferencias, utilizando como grupo de control el conjunto de mercados americanos con mayor volumen de ventas en los previamente las empresas fusionadas no competían. Los resultados obtenidos apuntan a la existencia de un comportamiento anticompetitivo que se habría manifestado en Norteamérica antes de que la fusión se completara. Palabras clave: fusión, ordenadores personales, canibalización, diferencias-endiferencias, análisis retrospectivo. JEL: L13, L41, L42, L81.

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El present projecte està enfocat en la mecanització de micro-canals, on la fabricació anivell micro s’entén per a mecanitzacions de menys de 1 mil•límetre, mitjançantl’electroerosió i s’emmarca dins el grup de recerca en enginyeria del producte procés iproducció (GREP) de la universitat de Girona. Avui en dia la biomedicina és un sectorque està creixent i representa una gran oportunitat per a aquest tipus de mecanitzat, jaque alguns productes són de mida micromètrica i es necessita una alternativa almecanitzat tradicional per tal d’abaratir costos, guanyar precisió i qualitat superficial.La mecanització de micro-canals, geometria utilitzada en aquest sector, de granprecisió i elevat acabat superficial són requisits necessaris per donar respostes a lesnecessitats d’aquest camp. L’acer inoxidable 316L és un material molt utilitzat enbiomedicina gràcies a la seva biocompatibilitat. Exemples de la seva aplicació podenser els implants, les pròtesis, utensilis mèdics, etc

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LLIBRE DE CÁLCUL AMB EL PROGRAMA EXCELL PER REALITZAR EL DIMENSIONAT AUTOMÀTIC I LA OPTIMITZACIÓ DE NAUS INDUSTRIALS D’HACER. PERMET FER EL DIMENSIONAT D’ELEMENTS COM LES CORRETGES I PÒRTICS D’ANIMA PLENA. UTILITZA EL CÀLCUL MATRICIAL PER A REALITZAR ANÀLISIS TANT DE PRIMER COM DE SEGON ORDRE I PERMET COMPARAR DIFERENTS CONFIGURACIONS PER OBTENIR LA MÉS APROPIADA EN CADA CAS.

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Tesis (Maestría en Ciencias Biológicas con Especialidad en Entomología Médica) UANL

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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