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81	Micropayments through cryptocurrency mining Tigerström, Viktor January 2016 (has links) The monetary policies of states and systems built upon them do not naturally allow transactions of a very small value, as the transaction costs exceeds the actual value of the transaction. These types of transactions are called micropayments. This is problematic as it removes the possibility to monetize content that has a valuation that is so low that the costs of the transaction exceeds the value of the content. In this thesis we aim to create a system that allows micropayments to monetize low value content. We do so by developing a design theory based on Gregor and Jones conceptual model for design theories within Information Systems research. The system that we develop will use the end users computational power to generate a value, by running a cryptocurrency miner. We present the background knowledge required to fully understand the presented design theory. Within the design theory, we present a theoretical framework to base systems on that enables micropayments through cryptocurrency mining. We also present a developed proof of work prototype that proves the validity of the theoretical framework. Lastly we discuss our design theory. We conclude that the design theory enables transactions of a very low value, such as 0,0001 \$ cents. Transactions of such small value is not possible with systems built upon states monetary policies. We also conclude that the proposed design theory can be further developed to function independently of cryptocurrency mining. Instead the value for the transaction could be generated through solving complicated problems if institutions are willing to pay for computational power to solve them. cryptocurrency blockchain proof of work bitcoin cryptography crypto currency monero bitcoin mining crypto currency mining cryptocurrency mining micropayment microtransaction micro payment micro transaction block chain blockchain technology block chain technology stratum Information Systems
82	Urychlení těžby Bitcoinů / Bitcoin Mining Acceleration Novotný, Jan January 2014 (has links) This master's thesis deals with virtual currency called Bitcoin. It describes the functioning of the currency of technical perspective especially the implementation of the transaction, the way of its validation and ensuring the integrity by using cryptographic functions. Furthermore, it describes the principle of the Bitcoin creation, particularly mining method called pooled mining. The thesis also describes the communication protocols and design of architecture to acceleration of the bitcoin mining. Finally, there are described tests, assessment and proposals for the continuation of work.
83	Comprendre l’imperméabilité cutanée : étude spectroscopique de mélanges modèles de la phase lipidique du stratum corneum Paz Ramos, Adrian 03 1900 (has links) No description available. stratum corneum membranes modèles comportement de phase lipides peau acides gras à très longue chaîne phospholipides model membranes phase behavior lipids skin very-long chain fatty acids phospholipids.
84	Produire la ville avec les Chinois en Afrique : l'impact des pratiques chinoises d'urbanisme dans les trajectoires urbaines africaines / China and the Making of African Cities : the impact of Chinese urban development practices on Africa’s path of urbanization Bénazéraf, David 19 December 2014 (has links) À travers des projets d’une échelle inégalée, les acteurs chinois contribuent à la transformation des villes africaines. Le développement urbain constitue un secteur émergent des relations sino-africaines.Combinant aide publique et capitaux privés, plusieurs catégories d’acteurs – instituts d’urbanisme, entreprises de construction, promoteurs privés – y conçoivent et construisent des projets de nature variée à différentes échelles : routes urbaines, résidences de logements, villes satellites,zones économiques spéciales conçues comme des villes nouvelles. Les productions urbaines chinoises en Afrique accélèrent la métropolisation des plus grandes villes du continent et densifient leurs espaces périurbains : elles contribuent à la formation d’une nouvelle strate urbaine. Les projets chinois accompagnent l’émergence des classes moyennes africaines en facilitant l’accession à un meilleur confort de vie. Parallèlement, l’exportation de pratiques chinoises d’urbanisme véhicule une image de réussite et participe au renforcement de la puissance chinoise. / Urban development has become a growing sector within China-Africa relations. The Chinese contribute to the urbanization process in Africa. By combining development aid and business, a number of Chinese stakeholders – urban planning and design institutes, construction firms, and real estate developers – design and build there, on various scales, a great variety of projects such as urban roads, housing estates, satellite-towns, special economic zones planned as new cities. Chinese urban development projects in Africa have sped up the metropolization processin the largest African cities by making suburban areas denser and denser. This has contributed to the development of a new urban stratum in Africa. Chinese projects have been boosting the rise of the African urban middle class by facilitating access to better standards of living. At the same time, the export of Chinese urban development practices conveys an image of success andallows China to strengthen its soft power. / 中国对非洲城市发展的贡献: 中国城市规划式对非洲城市化的影响城市发展已成为中非合作越来越重要的行业。中国对非洲城市化进程作出了贡献。众多中国城市建设专业机构(城市规划设计研究院，施工企业，房地产开发商)在非洲设计和建造各类的城市发展项目: 城市道路、住宅区、卫星城市和经济特区。中国在非洲城市发展项目对加快特大城市的大都市化和密集化作出了贡献。这些项目已经推动一些非洲城市开始产生新的城市阶层。在非洲的中国项目推动非洲中产阶层的崛起，帮助他们方便获得更好的生活条件。同时，中国城市规划设计的走出去传达中国城市发展的成功形象，有利于中国加强自己的软实力。关键词：中非合作，城市发展，城市发展实践，大都市化，城市阶层，房地产，全球化，软实力，援助，新兴国家和发展中国家。 Chine-Afrique Développement urbain Pratiques d’urbanisme Métropolisation Strates urbaines Immobilier Mondialisation Soft power Aide au développement Pays émergents et en développement China-Africa Urban development Urban development practices Metropolization Urban stratum Real estate Globalization Soft power Development aid Emerging and developing countries 中非合作城市发展城市发展实践大都市化城市阶层房地产全球化软实力援助新兴国家和发展中国家 711 307.76 337.6
85	Methodological investigations on vegetation typology and phytogeography of rain forests of tropical Africa Senterre, Bruno B.M.L. 17 June 2005 (has links) I. An original methodological discussion is proposed on the problem of the typology of tropical rain forest’s plant communities, based on the study of forest types across gradients of continentality and elevation, within Atlantic central Africa. These investigations were based on the statement that the main problems in forest typology are related to the non-zonal or zonal character of the different vegetation types and to non considering the relations and differences between forest strata. II. Field data consisted in phytosociological homogeneous sample plots localized within different recognized phytogeographical entities, in a region of tropical Africa where these entities are known to be well conserved. A total of 37 such plots were inventoried in the region extending from the littoral forests of Ndoté, Equatorial Guinea, which are wet evergreen forests, to the continental forests of the Dja, Cameroon, known as evergreen seasonal forests. The studied region also included the oriental Atlantic forests of Equatorial Guinea, known as moist evergreen forests or caesalp forests. In various parts of this continentality gradient, some plots were localized within climax non-zonal formations, namely the submontane rain forests. The emphasis was put on the vegetation of the Monte Alén National Park. The sampling methodology was willing to be as "complete ", including all strata, "quantitative ", enumerating all individuals, and "representative ", within each stratum, as possible. These multi-layers plots were realised using nested sub-plots, with a sampling size of 100 individuals for every ligneous stratum recognized (dominant trees, dominated trees and shrubs) and a sampling size of 200m² for the herbaceous and suffrutex stratum. Forest types were defined independently for each stratum and the differences were analysed. A method was proposed for the simultaneous analysis of all floristic data, converting and standardizing the values from ligneous strata, on the one hand, and from understorey strata, on the other hand. III. Ten forest types were described using IndVal and discussed in the general context of the guineo-congolian region, from a syntaxonomic view point (agglomerative classification) and from a phytogeographical view point (divisive classification). Homologies between these two approaches are described. The proposed phytogeographical system is based on an "open " conception of hierarchical classifications, combining advantages of agglomerative and divisive classifications. In concrete terms, the non-zonal criteria, for example the submontane variants, are categorised separately and in analogy with the zonal criteria, related to the usual phytochoria. Analysis of ecological relationships for the 10 communities showed that the main variables related to the floristic variability in our mainland rain forests are elevation, rainfall, hygrometry (estimated using bryophytes cover levels) and distance to the ocean. The two extremes on the vertical microclimatic gradient, dominant trees stratum and herbaceous stratum, give similar typologies, however canonical analysis showed that for the herbaceous layer, non-zonal variables (hygrometry and elevation) were gaining more importance when the influence of the two zonal variables was attenuated. In every case, spatial autocorrelation was less important than the environment in explaining floristic variability but its role increased in the spatial arrangement of understorey species, whose dispersal capacity is generally lower than canopy trees. The phytosociological, phytogeographical and ecological description of forest types is accompanied by a physiognomical description using biological types spectrum, as well as architectural models, leaf sizes, etc. With regard to diversity, we have demonstrated that species richness was higher from upper to lower strata because of the accumulation in lower strata of species from various strata. On the other hand, the proper stratum diversity, i.e. the structural set, decreased from dominant trees to shrubs. The proper diversity of the herb layer showed relatively high figures mainly due to the higher individual density in relation to the existence of microstrata. Within the 37 sample plots, 1,050 taxa have been identified to species or morpho-species levels, for a total of 25,750 individuals. These taxa represent 442 genus among 104 families. The richest forest type is found on the foothills of the Niefang range, on the windward side. This forest type is also characterised by a high number of oligotypic genus and by species belonging to functional types indicators of glacial refuges. These functional types are defined on the basis of the dispersal capacity and on kind of stand needed for effective germination. We formulated the hypothesis that this kind of "foothills refuge ", characterised by his zonal nature, could have been one of the rare refuges for species from mainland rain forests, while montane and fluvial refuges would mainly have preserved species from non-zonal forest types: (sub)montane and riverine. Based on indicator species of submontane forests, a potential distribution map of this forest type has been realised at the Atlantic central African scale. More than 400 submontane forest localities have been mapped. These forests begin at 400m of altitude near the ocean, and progressively at higher altitude for increasing distance to the ocean. Many lowland localities also comprised submontane species, which could indicate the existence of ecological transgressions. These transgressions would allow migratory tracks for submontane species between isolated mountain ranges, not only during glacial periods, through heights at the northern and southern borders of the congo basin, but also contemporarily through the lowland riverine forest network, in the centre of this basin. Finally, a special attention has been attributed to littoral forests and to some cases of choroecological transgressions, coupled to the ecological equalization phenomenon. plant diversity foothills refuge glacial refuge environmental stability conservation rarefaction curves individuals-area curves species-area curves compensations écologiques Guinée Equatoriale Monte Alén Monts de Cristal Réserve de Ndoté rainforest transgression Monte Alén Cristal mountains strate forestière sous-bois ensemble structural groupe écologique modèles architecturaux guilde types fonctionnels synusie genres monotypiques genres paucispecifiques diversité végétale courbes aire-espèces courbes individus-espèces courbes de raréfaction courbes aire-constance aire minimale morpho-espèces pléistocène constancy-area curves minimal area structural ensemble understorey ecological group synusia oligotypic genus Réserve de Biosphère du Dja Cameroun Quaternaire glaciation refuge glaciaire refuge de pied de massifs montagneux stabilité environnementale conservation transgression forestière phytosociology plant community phytogeography open classification non-zonal nested plots forest types IndVal morphospecies pleistocene littoral forest rain forest afromontane submontane altitudinal belt glaciation Quaternary Equatorial Guinea ecological equalization continentality continentalité étage d’altitude forêt littorale forêt dense humide afromontagnard submontagnard IndVal types forestiers phytosociologie phytogéographie classification ouverte azonal relevés emboîtés multistrates monotypic genus architectural model guild plant functional type Ndoté Reserve Cameroon Dja Biosphere Reserve forest stratum forest layer understory
86	Recherches méthodologiques pour la typologie de la végétation et la phytogéographie des forêts denses d'Afrique tropicale Senterre, Bruno 17 June 2005 (has links) I. An original methodological discussion is proposed on the problem of the typology of tropical rain forest’s plant communities, based on the study of forest types across gradients of continentality and elevation, within Atlantic central Africa. These investigations were based on the statement that the main problems in forest typology are related to the non-zonal or zonal character of the different vegetation types and to non considering the relations and differences between forest strata.<p><p>II. Field data consisted in phytosociological homogeneous sample plots localized within different recognized phytogeographical entities, in a region of tropical Africa where these entities are known to be well conserved. A total of 37 such plots were inventoried in the region extending from the littoral forests of Ndoté, Equatorial Guinea, which are wet evergreen forests, to the continental forests of the Dja, Cameroon, known as evergreen seasonal forests. The studied region also included the oriental Atlantic forests of Equatorial Guinea, known as moist evergreen forests or caesalp forests. In various parts of this continentality gradient, some plots were localized within climax non-zonal formations, namely the submontane rain forests. The emphasis was put on the vegetation of the Monte Alén National Park.<p><p>The sampling methodology was willing to be as "complete ", including all strata, "quantitative ", enumerating all individuals, and "representative ", within each stratum, as possible. These multi-layers plots were realised using nested sub-plots, with a sampling size of 100 individuals for every ligneous stratum recognized (dominant trees, dominated trees and shrubs) and a sampling size of 200m² for the herbaceous and suffrutex stratum.<p><p>Forest types were defined independently for each stratum and the differences were analysed. A method was proposed for the simultaneous analysis of all floristic data, converting and standardizing the values from ligneous strata, on the one hand, and from understorey strata, on the other hand.<p><p>III. Ten forest types were described using IndVal and discussed in the general context of the guineo-congolian region, from a syntaxonomic view point (agglomerative classification) and from a phytogeographical view point (divisive classification). Homologies between these two approaches are described. The proposed phytogeographical system is based on an "open " conception of hierarchical classifications, combining advantages of agglomerative and divisive classifications. In concrete terms, the non-zonal criteria, for example the submontane variants, are categorised separately and in analogy with the zonal criteria, related to the usual phytochoria.<p><p>Analysis of ecological relationships for the 10 communities showed that the main variables related to the floristic variability in our mainland rain forests are elevation, rainfall, hygrometry (estimated using bryophytes cover levels) and distance to the ocean. The two extremes on the vertical microclimatic gradient, dominant trees stratum and herbaceous stratum, give similar typologies, however canonical analysis showed that for the herbaceous layer, non-zonal variables (hygrometry and elevation) were gaining more importance when the influence of the two zonal variables was attenuated. In every case, spatial autocorrelation was less important than the environment in explaining floristic variability but its role increased in the spatial arrangement of understorey species, whose dispersal capacity is generally lower than canopy trees. The phytosociological, phytogeographical and ecological description of forest types is accompanied by a physiognomical description using biological types spectrum, as well as architectural models, leaf sizes, etc.<p><p>With regard to diversity, we have demonstrated that species richness was higher from upper to lower strata because of the accumulation in lower strata of species from various strata. On the other hand, the proper stratum diversity, i.e. the structural set, decreased from dominant trees to shrubs. The proper diversity of the herb layer showed relatively high figures mainly due to the higher individual density in relation to the existence of microstrata. Within the 37 sample plots, 1,050 taxa have been identified to species or morpho-species levels, for a total of 25,750 individuals. These taxa represent 442 genus among 104 families. The richest forest type is found on the foothills of the Niefang range, on the windward side. This forest type is also characterised by a high number of oligotypic genus and by species belonging to functional types indicators of glacial refuges. These functional types are defined on the basis of the dispersal capacity and on kind of stand needed for effective germination. We formulated the hypothesis that this kind of "foothills refuge ", characterised by his zonal nature, could have been one of the rare refuges for species from mainland rain forests, while montane and fluvial refuges would mainly have preserved species from non-zonal forest types: (sub)montane and riverine.<p><p>Based on indicator species of submontane forests, a potential distribution map of this forest type has been realised at the Atlantic central African scale. More than 400 submontane forest localities have been mapped. These forests begin at 400m of altitude near the ocean, and progressively at higher altitude for increasing distance to the ocean. Many lowland localities also comprised submontane species, which could indicate the existence of ecological transgressions. These transgressions would allow migratory tracks for submontane species between isolated mountain ranges, not only during glacial periods, through heights at the northern and southern borders of the congo basin, but also contemporarily through the lowland riverine forest network, in the centre of this basin. Finally, a special attention has been attributed to littoral forests and to some cases of choroecological transgressions, coupled to the ecological equalization phenomenon.<p> / Doctorat en sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished Sciences exactes et naturelles Agronomie générale Phytogeography -- Africa, Sub-Saharan Forest surveys -- Africa, Sub-Saharan Phytogéographie -- Afrique noire Inventaires forestiers -- Afrique noire submontane afromontane rain forest littoral forest pleistocene morphospecies IndVal forest types nested plots non-zonal open classification phytogeography plant community phytosociology transgression forestière conservation stabilité environnementale refuge de pied de massifs montagneux refuge glaciaire glaciation Quaternaire Cameroun Réserve de Biosphère du Dja oligotypic genus synusia ecological group understorey structural ensemble minimal area constancy-area curves pléistocène morpho-espèces aire minimale courbes aire-constance courbes de raréfaction courbes individus-espèces courbes aire-espèces diversité végétale genres paucispecifiques genres monotypiques synusie types fonctionnels guilde modèles architecturaux groupe écologique ensemble structural sous-bois strate forestière Cristal mountains Monte Alén rainforest transgression Réserve de Ndoté Monts de Cristal Guinée Equatoriale compensations écologiques species-area curves individuals-area curves rarefaction curves environmental stability glacial refuge foothills refuge plant diversity altitudinal belt Quaternary Equatorial Guinea ecological equalization continentality continentalité étage d’altitude forêt littorale forêt dense humide afromontagnard submontagnard types forestiers phytosociologie phytogéographie classification ouverte azonal relevés emboîtés multistrates monotypic genus architectural model guild plant functional type Ndoté Reserve Cameroon Dja Biosphere Reserve forest stratum forest layer understory

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