961 resultados para Paix d’Apamée, 188 av. J.-C.


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The respiratory chain is found in the inner mitochondrial membrane of higher organisms and in the plasma membrane of many bacteria. It consists of several membrane-spanning enzymes, which conserve the energy that is liberated from the degradation of food molecules as an electrochemical proton gradient across the membrane. The proton gradient can later be utilized by the cell for different energy requiring processes, e.g. ATP production, cellular motion or active transport of ions. The difference in proton concentration between the two sides of the membrane is a result of the translocation of protons by the enzymes of the respiratory chain, from the negatively charged (N-side) to the positively charged side (P-side) of the lipid bilayer, against the proton concentration gradient. The endergonic proton transfer is driven by the flow of electrons through the enzymes of the respiratory chain, from low redox-potential electron donors to acceptors of higher potential, and ultimately to oxygen. Cytochrome c oxidase is the last enzyme in the respiratory chain and catalyzes the reduction of dioxygen to water. The redox reaction is coupled to proton transport across the membrane by a yet unresolved mechanism. Cytochrome c oxidase has two proton-conducting pathways through which protons are taken up to the interior part of the enzyme from the N-side of the membrane. The K-pathway transfers merely substrate protons, which are consumed in the process of water formation at the catalytic site. The D-pathway transfers both substrate protons and protons that are pumped to the P-side of the membrane. This thesis focuses on the role of two conserved amino acids in proton translocation by cytochrome c oxidase, glutamate 278 and tryptophan 164. Glu278 is located at the end of the D-pathway and is thought to constitute the branching point for substrate and pumped protons. In this work, it was shown that although Glu278 has an important role in the proton transfer mechanism, its presence is not an obligatory requirement. Alternative structural solutions in the area around Glu278, much like the ones present in some distantly related heme-copper oxidases, could in the absence of Glu278 support the formation of a long hydrogen-bonded water chain through which proton transfer from the D-pathway to the catalytic site is possible. The other studied amino acid, Trp164, is hydrogen bonded to the ∆-propionate of heme a3 of the catalytic site. Mutation of this amino acid showed that it may be involved in regulation of proton access to a proton acceptor, a pump site, from which the proton later is expelled to the P-side of the membrane. The ion pair that is formed by the ∆-propionate of heme a3 and arginine 473 is likely to form a gate-like structure, which regulates proton mobility to the P-side of the membrane. The same gate may also be part of an exit path through which water molecules produced at the catalytically active site are removed towards the external side of the membrane. Time-resolved optical and electrometrical experiments with the Trp164 to phenylalanine mutant revealed a so far undetected step in the proton pumping mechanism. During the A to PR transition of the catalytic cycle, a proton is transferred from Glu278 to the pump site, located somewhere in the vicinity of the ∆-propionate of heme a3. A mechanism for proton pumping by cytochrome c oxidase is proposed on the basis of the presented results and the mechanism is discussed in relation to some relevant experimental data. A common proton pumping mechanism for all members of the heme-copper oxidase family is moreover considered.

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WM-data tillhandahåller en lösning för mobil arbetsorderhantering. Lösningen innehåller planeringsverktyg med ärenden, personal och karta och möjlighet att leverera arbetsorder till fältpersonal. Den innehåller dessutom handhållna mobilenheter, vilka fältpersonalen använder för att ta emot aktuella arbetsorder.Vissa kunder önskar ytterligare en modul i denna mobila lösning. Den nya modulen skall användas för att kontinuerligt rapportera in genomförda åtgärder i snöröjningssammanhang.Detta examensarbete går ut på att utveckla den här modulen för att registrera snöröjning respektive sandning. Applikationen exekveras på en PDA, en så kallad Pocket PC med Windows Mobile 5.0. Anledningen till att just Windows Mobile 5.0 skall användas är att detta operativsystem har inbyggt stöd för GPS-positionering. Ett önskemål av WM-data var att detta inbyggda stöd skulle undersökas, rapporteras och användas i applikationen.Resultatet blev en applikation där man via en Pocket PC kontinuerligt sparar undan fordons GPS-position, arbetsåtgärd samt tidpunkterna när GPS-positionerna togs. Denna information är sedan anpassad för att kunna skickas vidare via GPRS till en befintlig databasserver under vissa tidsintervaller.Applikationen utvecklades med hjälp av programmeringsspråket C Sharp (C#) i Visual Studio 2005.

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La epigrafía latina nos ha legado el recuerdo de doce docentes y un grupo de maestros de escuela en Hispania. Los diferentes textos, la mayoría de carácter funerario y procedente del ámbito urbano, nos aportan información acerca de las funciones que estos profesionales desempeñaron en la sociedad hispana, así como del contexto socio-jurídico del que provenían. En este sentido, la pieza más valiosa es la inscripción dedicada a un gramático llamado L. Memmius Probus en la antigua Tritium Magallum, gracias a la cual conocemos las circunstancias concretas en las que trabajó este educador.

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Adult-type hypolactasia (primary lactose malabsorption, lactase non-persistence) is the most common enzyme deficiency worldwide, and manifests with symptoms of lactose intolerance such as abdominal pain, gas formation and diarrhea. In humans with adult-type hypolactasia, lactase activity is high at birth, but declines during childhood to about one-tenth of the activity at birth. In 2002, a one base polymorphism C/T-13910, located 14 kilobases from the starting codon of the lactase-phlorizin hydrolase (LPH) gene was observed to be associated with the persistence of lactase activity. The T-13910 allele (C/T-13910 and T/T-13910 genotypes) associates with persistence of lactase activity throughout life, whereas the C/C-13910 genotype associates with adult-type hypolactasia. In this thesis work, the timing and mechanism of decline of lactase enzyme activity during development was studied using the C/T-13910 polymorphism as a molecular marker. We observed an excellent correlation between low lactase activity and the C/C-13910 genotype in all subjects > 12 years of age, irrespective their ethnicity. In children of African origin, the lactase activity declined somewhat earlier than among Finnish children. Furthermore, we observed an increasing imbalance in the relative lactase mRNA expression from the C-13910 and T-13910 alleles in Finnish children beginning from five years of age. The genetic test for adult-type hypolactasia showed a sensitivity of 93% and a specificity of 100% in the Finnish children and adolescents > 12 years of age. The relation of milk consumption and the milk-related abdominal complaints to the C/T-13910 genotypes associated with lactase persistence/non-persistence was studied by a questionnaire-based approach in > 2100 Finns. Both Finnish children and adults with the C/C-13910 genotype consumed significantly less dairy products compared to those with the C/T-13910 and T/T-13910 genotypes. Flatulence was the only of the abdominal symptoms of lactose intolerance that subjects with the C/C-13910 genotype reported significantly more often than those with the C/T-13910 and T/T-13910 genotypes. A minor proportion (<10%) of subjects with the C/C-13910 genotype, nevertheless, reported drinking milk without any symptoms afterwards. There was no association between cow's milk allergy starting as a newborn and adult-type hypolactasia. In an association study an increased risk of colorectal cancer was observed among those with molecular diagnosis of adult-type hypolactasia. It warrants further studies to clarify whether the increased risk observed in the Finnish population is associated with lactose or decreased intake of dairy products in these subjects.

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Increased anthropogenic loading of nitrogen (N) and phosphorus (P) has led to an eutrophication problem in the Baltic Sea, and the spring bloom is a key component in the biological uptake of increased nutrient concentrations. The spring bloom in the Baltic Sea is dominated by both diatoms and dinoflagellates. However, the sedimentation of these groups is different: diatoms tend to sink to the sea floor at the end of the bloom, while dinoflagellates to a large degree are been remineralized in the euphotic zone. Understanding phytoplankton competition and species specific ecological strategies is thus of importance for assessing indirect effects of phytoplankton community composition on eutrophication problems. The main objective of this thesis was to describe some basic physiological and ecological characteristics of the main cold-water diatoms and dinoflagellates in the Baltic Sea. This was achieved by specific studies of: (1) seasonal vertical positioning, (2) dinoflagellate life cycle, (3) mixotrophy, (4) primary production, respiration and growth and (5) diatom silicate uptake, using cultures of common cold-water diatoms: Chaetoceros wighamii, C. gracilis, Pauliella taeniata, Thalassiosira baltica, T. levanderi, Melosira arctica, Diatoma tenuis, Nitzschia frigida, and dinoflagellates: Peridiniella catenata, Woloszynskia halophila and Scrippsiella hangoei. The diatoms had higher primary production capacity and lower respiration rate compared with the dinoflagellates. This difference was reflected in the maximum growth rate, which for the examined diatoms range from 0.6 to 1.2 divisions d-1, compared with 0.2 to 0.3 divisions d-1 for the dinoflagellates. Among diatoms there were species specific differences in light utilization and uptake of silicate, and C. wighamii had the highest carbon assimilation capacity and maximum silicate uptake. The physiological properties of diatoms and dinoflagellates were used in a model of the onset of the spring bloom: for the diatoms the model could predict the initiation of the spring bloom; S. hangoei, on the other hand, could not compete successfully and did not obtain positive growth in the model. The other dinoflagellates did not have higher growth rates or carbon assimilation rates and would thus probably not perform better than S. hangoei in the model. The dinoflagellates do, however, have competitive advantages that were not included in the model: motility and mixotrophy. Previous investigations has revealed that the chain-forming P. catenata performs diurnal vertical migration (DVM), and the results presented here suggest that active positioning in the water column, in addition to DVM, is a key element in this species' life strategy. There was indication of mixotrophy in S. hangoei, as it produced and excreted the enzyme leucine aminopeptidase (LAP). Moreover, there was indirect evidence that W. halophila obtains carbon from other sources than photosynthesis when comparing increase in cell numbers with in situ carbon assimilation rates. The results indicate that mixotrophy is a part of the strategy of vernal dinoflagellates in the Baltic Sea. There were also indications that the seeding of the spring bloom is very important for the dinoflagellates to succeed. In mesocosm experiments dinoflagellates could not compete with diatoms when their initial numbers were low. In conclusion, this thesis has provided new information about the basic physiological and ecological properties of the main cold-water phytoplankton in the Baltic Sea. The main phytoplankton groups, diatoms and dinoflagellates, have different physiological properties, which clearly separate their life strategies. The information presented here could serve as further steps towards better prognostic models of the effects of eutrophication in the Baltic Sea.

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Traducido por Iñaki Villoslada Fernández

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A presente tese investiga as poéticas do trágico nas obras teatrais de Eurípides (Grécia, c. 484 406 a.C.), Johann Wolfgang von Goethe (Alemanha, 1749 1832) e Federico García Lorca (Espanha, 1898 1936) e defende que, nos três autores, as concepções estéticas do trágico se constituem principalmente sobre a representação poética do filicídio materno. A antinomia trágica engendrada, metaforicamente, no assassinato da criança pelas mãos daquela que lhe deu a vida é tema de Medeia (431 a.C.), Tragédia de Margarida (1790) e Yerma (1934), obras fundamentais para compreender a visada trágica dos três poetas aqui, em respectivo, estudados. O conflito com o sagrado e com a razão, ao apontar para a afirmação trágica do corpo e do feminino, frequenta as três obras. O paralelismo entre as dimensões política e estética é, por conseguinte, patente nos três dramas, ao mesmo tempo em que cada um dos autores, com contexto e assinatura próprios, configura uma ideia estética acerca do trágico inteiramente singular. O diálogo entre literatura e filosofia, ou entre intuição e conceito, atravessa, nesta tese, a leitura do trágico na metáfora do filicídio. Sob tal perspectiva, a Medeia de Eurípides impõe-se no centro do debate entre socráticos e sofistas, e aborda temas, como o domínio das paixões sobre a razão, que também aliciaram autores como Platão, Aristóteles e Nietzsche. A Gretchentragödie, de Goethe, apresenta-se, por sua vez, como obra poética aonde convergem as mais calorosas discussões estéticas do moderno pensamento alemão, como as questões do sublime (Kant, Schiller) e da vontade (Schopenhauer). Yerma, de García Lorca, será também uma obra de convergência filosófica, expressando a nueva manera espiritualista que marca a última fase da produção lorquiana: a perspectiva trágica de Nietzsche, na afirmação do corpo como grande razão, assim como o diálogo de Lorca com o pensamento de Miguel de Unamuno sobre El sentimiento trágico de la vida, caracteriza uma espécie de tragédia às avessas, que nega o sagrado e afirma o trágico como síntese libertária do eu, do corpo e do feminino

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The current global environment and the general increase in the spread and use of Information Technology and Communication (ICT) by companies and consumers, make the use of these technologies as essential to confront the growing competition in the market. Focused on this sector, in this research we analyze the use of electronic commerce, as through websites as through electronic markets, and the use of social networking tools as enablers of business. For this aim, we conducted a comparative analysis between the Andalusian olive oil cooperatives and other legal forms which are present in the sector.

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[La république (français). 1791]