924 resultados para distribution patterns


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Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

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Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

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Tese de doutoramento, Biologia (Ecologia), Universidade de Lisboa, Faculdade de Ciências, 2014

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Tese de Doutoramento, Física, 17 de Dezembro de 2013, Universidade dos Açores.

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Abiotic factors are considered strong drivers of species distribution and assemblages. Yet these spatial patterns are also influenced by biotic interactions. Accounting for competitors or facilitators may improve both the fit and the predictive power of species distribution models (SDMs). We investigated the influence of a dominant species, Empetrum nigrum ssp. hermaphroditum, on the distribution of 34 subordinate species in the tundra of northern Norway. We related SDM parameters of those subordinate species to their functional traits and their co-occurrence patterns with E. hermaphroditum across three spatial scales. By combining both approaches, we sought to understand whether these species may be limited by competitive interactions and/or benefit from habitat conditions created by the dominant species. The model fit and predictive power increased for most species when the frequency of occurrence of E. hermaphroditum was included in the SDMs as a predictor. The largest increase was found for species that 1) co-occur most of the time with E. hermaphroditum, both at large (i.e. 750 m) and small spatial scale (i.e. 2 m) or co-occur with E. hermaphroditum at large scale but not at small scale and 2) have particularly low or high leaf dry matter content (LDMC). Species that do not co-occur with E. hermaphroditum at the smallest scale are generally palatable herbaceous species with low LDMC, thus showing a weak ability to tolerate resource depletion that is directly or indirectly induced by E. hermaphroditum. Species with high LDMC, showing a better aptitude to face resource depletion and grazing, are often found in the proximity of E. hermaphroditum. Our results are consistent with previous findings that both competition and facilitation structure plant distribution and assemblages in the Arctic tundra. The functional and co-occurrence approaches used were complementary and provided a deeper understanding of the observed patterns by refinement of the pool of potential direct and indirect ecological effects of E. hermaphroditum on the distribution of subordinate species. Our correlative study would benefit being complemented by experimental approaches.

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Segment poses and joint kinematics estimated from skin markers are highly affected by soft tissue artifact (STA) and its rigid motion component (STARM). While four marker-clusters could decrease the STA non-rigid motion during gait activity, other data, such as marker location or STARM patterns, would be crucial to compensate for STA in clinical gait analysis. The present study proposed 1) to devise a comprehensive average map illustrating the spatial distribution of STA for the lower limb during treadmill gait and 2) to analyze STARM from four marker-clusters assigned to areas extracted from spatial distribution. All experiments were realized using a stereophotogrammetric system to track the skin markers and a bi-plane fluoroscopic system to track the knee prosthesis. Computation of the spatial distribution of STA was realized on 19 subjects using 80 markers apposed on the lower limb. Three different areas were extracted from the distribution map of the thigh. The marker displacement reached a maximum of 24.9mm and 15.3mm in the proximal areas of thigh and shank, respectively. STARM was larger on thigh than the shank with RMS error in cluster orientations between 1.2° and 8.1°. The translation RMS errors were also large (3.0mm to 16.2mm). No marker-cluster correctly compensated for STARM. However, the coefficient of multiple correlations exhibited excellent scores between skin and bone kinematics, as well as for STARM between subjects. These correlations highlight dependencies between STARM and the kinematic components. This study provides new insights for modeling STARM for gait activity.

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The formation of the Sar Cheshmeh porphyry Cu-Mo deposit is related to the culmination of calc-alkaline igneous activity in the Kerman region. The deposit comprises a suite of Late Cenozoic intrusive sub-volcanic and extrusive rocks emplaced into a folded series of Eocene andesitic lavas and pyroclastic sediments. The earliest stage of magmatism was emplacement of a large granodiorite stock about 29 m.y.b.p. This was followed by intrusion of two separate porphyritic bodies at 15 (Sar Cheshrneh porphyry) and 12 m.y.b.p. (Late porphyry) and a series of sub-volcanic dikes between 12 and 9 m.y.b.p. Magmatic activity terminated with multi-phase extrusion of a Pelean dacitic dome complex between 10 and 2.8 m.y.b.p. The country rocks and the earlier porphyritic intrusions are pervasively altered to biotite-rich potassium silicate (metasomatic and hydrothermal) sericite-clay, phyllic and chlorite-clay, argillic assemblages. These grade outwards to an extensive propylitic zone. Within the ore body, the later intra-. and post-mineral dikes only reach the propylitic grade. At least three different sets of quartz veins are present, including a sericite-chlorite-quartz set which locally retrogrades pervasive secondary biotite to sericite. In the hypogene zone, metasomatic and hydrothermal alteration is related to all stages of magmatism but copper mineralization and veining are restricted to a period of 15 to 9 m.y.b.p.related to the early intrusive phases. The copper mineralization and silicate alteration do not fit a simple annular ring model but have been greatly modified by, 1. The existence of an ititial, outer ring, of metasomatic alteration overprinted by an inner.ring of hydrothermal alteration and, 2. later extensive dilating effects of intra- and post-mineral dikes. The hydrothermal clay mineral assemblage in the hypogene zone is illite-chlorite-kaolinite-smectite (beidellite). Preliminary studies indicate that the amount of each of these clays varies vertically and that hydrothermal zonation of clay minerals is possible. However, these minerals alter to illite-kaolinite assemblages in the supergene sulfide zone and to more kaolinite-rich assemblages in the supergene leached zone. Hydrothermal biotite breaks down readily in the supergene zone and is not well preserved in surface outcrops. The distribution of copper minerals in the supergene sulfide enrichment zone is only partly related to rock type being more dependent on topography and the availability of fractures.

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Affiliation: Pascal Michel : Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal

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La présente recherche traite des conflits d’aménagement pouvant être décelés dans les cuisines domiciliaires modernes. L’ajout d’objets mécanisés au rituel alimentaire quotidien a su changer la dynamique du lieu. En effet, l’architecture des cuisines modernes en Occident présente de grandes contradictions. Basées sur des standards architecturaux, les cuisines modulaires ne reflètent pas la variété et l’unicité des aliments auxquels les cuisines sont dédiées. Les cuisines devraient être le miroir de la vivacité naturelle des aliments et des échanges humains que la nourriture génère à travers le plaisir et le partage. Dans l’espoir de proposer des outils afin de rééquilibrer la dynamique de cette pièce, un cadre théorique basé sur les théories architecturales de l’architecte et mathématicien anglais Christopher Alexander a été établi. Supportant la présente recherche, ces théories architecturales s’inspirent de la structure et de la composition des choses de la nature et des monuments anciens afin d’établir des balises d’aménagement simples et équilibrées (qualité de vie, patterns, configuration des événements, configurations de l’espace, ...). Ces théories ont aidé à concevoir une formule d’ateliers participatifs qui visent à outiller les occupants, qui sont très souvent des non-professionnels du domaine de l’architecture et du design. Ces ateliers proposent un cheminement bien encadré qui permet aux participants de retravailler leur espace de cuisine respectif selon leurs goûts et leurs besoins. En fournissant un plan de l’étage où se situe la cuisine, quelques crayons, règles et autres matériel de dessin, les participants ont pour tâche de réaménager leur cuisine en un espace de cuisine idéal. La deuxième étape, qui elle se réalise en équipe avec tous les occupants participants de la demeure, consiste à réduire l’ampleur des changements afin d’arriver à un résultat réaliste. L’enthousiasme noté tout au long de ce processus a ainsi permis de confirmer que les non-professionnels du domaine de l’architecture et du design peuvent développer un intérêt marqué pour l’amélioration de leurs interactions quotidiennes, avec l’espace et entre les occupants, lorsque bien accompagnés dans cette tâche. Grâce aux propos et aux plans recueillis durant les séances d’ateliers participatifs ainsi qu’à l’analyse de ces données, une série d’interprétations ont émergé. Les données ont notamment démontrées l’influence positive de l’utilisation des patterns d’Alexander. L’analyse permet, en outre, de noter les tendances d’aménagement ayant émergé de l’utilisation des patterns dans les espaces de cuisine : définitivement, les cuisines se sont transformées en espace de vie partagé et polyvalent. Finalement, la présente recherche se conclut grâce à une série de recommandations qui traitent de la structure des cuisines, des ateliers participatifs et des patterns. Tout d’abord, l’impact de ces notions sur les espaces retravaillés par les participants est impressionnant. Les espaces sont bien organisés, vastes et, surtout, reflètent les occupants qui y vivent au quotidien. De plus, ayant démontré la facilité d’utilisation et la polyvalence des patterns, il a été jugé que certains aspects devraient être améliorés tels que l’actualisation de certains patterns, le prolongement du processus d’ateliers, le perfectionnement de la méthode et la diffusion des résultats.

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An attempt is made to determine the relative power distribution in a step-index parabolic cylindrical waveguide (PCW) with high deformation across the direction of propagation. The guide is assumed to be made of silica. The scalar field approximation is employed for the analysis under which a vanishing refractive-index (RI) difference in the waveguide materials is considered. Further, no approximation for folds- is used in the analytical treatment. Due to the geometry of such waceguides, PCWs lose the well-defined modal discreteness, and a kind of mode bunching is observed instead, which becomes much more prominent in PCWs with high bends. However, with the increase in cross-sectional size, the mode-bunching tendency is slightly reduced. The general expressions for power in the guiding and nonguiding sections are obtained, and the fractional power patterns in all of the sections are presented for PCWs of various cross-sectional dimensions. It is observed that the confinement of power in the core section is increased for PCWs of larger cross-sectional size. Moreover, a fairly uniform distribution of power is seen over the modes having intermediate values of propagation constants

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This doctoral thesis addresses the growing concern about the significant changes in the climatic and weather patterns due to the aerosol loading that have taken place in the Indo Gangetic Plain(IGP)which includes most of the Northern Indian region. The study region comprises of major industrial cities in India (New Delhi, Kanpur, Allahabad, Jamshedpur and Kolkata). Northern and central parts of India are one of the most thickly populated areas in the world and have the most intensely farmed areas. Rapid increase in population and urbanization has resulted in an abrupt increase in aerosol concentrations in recent years. The IGP has a major source of coal; therefore most of the industries including numerous thermal power plants that run on coal are located around this region. They inject copious amount of aerosols into the atmosphere. Moreover, the transport of dust aerosols from arid locations is prevalent during the dry months which increase the aerosol loading in theatmosphere. The topography of the place is also ideal for the congregation of aerosols. It is bounded by the Himalayas in the north, Thar Desert in the west, the Vindhyan range in the south and Brahmaputra ridge in the east. During the non‐monsoon months (October to May) the weather in the location is dry with very little rainfall. Surface winds are weak during most of the time in this dry season. The aerosols that reach the location by means of long distance transport and from regional sources get accumulated under these favourable conditions. The increase in aerosol concentration due to the complex combination of aerosol transport and anthropogenic factors mixed with the contribution from the natural sources alters the optical properties and the life time of clouds in the region. The associated perturbations in radiative balance have a significant impact on the meteorological parameters and this in turn determines the precipitation forming process. Therefore, any change in weather which disturbs the normal hydrological pattern is alarming in the socio‐economic point of view. Hence, the main focus of this work is to determine the variation in transport and distribution of aerosols in the region and to understand the interaction of these aerosols with meteorological parameters and cloud properties.

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Els sistemes aquàtics continental representen un dels ecosistemes més amenaçats a nivell mundial, com a conseqüència de l'ús intensiu quel'home en fa. La conca del Guadiana no està lliure d'aquestes pressions antròpiques. Les grans infraestructures hidràuliques i l'escorrentia provinent de l'agricultura són només exemples dels greus problemes que pateix la conca. Aquests problemes es fan especialment palesos en la zona alta de la conca, on l'escassetat d'aigua no fa més que agreujar el problema.Tot això ha generat la necessitat urgent d'avaluar l'estat de conservació d'aquests ecosistemes aquàtics continentals, poder determinar la mesura i la magnitud de les pertorbacions que els estan afectant i així proposar mesures de gestió destinades a restaurar-ne la integritat ecològica. El principal objectiu que presenta aquest és determinar els patrons de distribució de les comunitats de algals (amb una menció especial en el grup de les diatomees) i de les seves causes en la conca del Guadiana i associades, amb la finalitat d'establir i proposar eines que permetin avaluar l'estat de conservació de les masses d'aigua d'aquestes conques.

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Aquesta tesi tracta la jerarquia i l'heterogeneïtat dels sistemes fluvials que afecten l'estructura de les comunitats bentòniques de diatomees. A nivell regional, es van buscar diferents grups de punts i les seves espècies indicadores, es va estudiar la resposta de les comunitats de diatomees als gradients ambientals, es va avaluar la utilitat de diferents índexs de diatomees i es va buscar el millor sistema de classificació per a condicions de referència. A nivell de conca, es volien definir els factors que determinen la distribució longitudinal de la diversitat de les comunitats de diatomees. Finalment, a nivell d'hàbitat es van determinar quins factors afecten les algues i els cianobacteris a aquesta escala i es va examinar la contribució relativa de l'ambient i l'espai en la distribució de la biomassa i composició d'algues i cianobacteris. Per tant, els diferents capítols d'aquesta tesi han estat desenvolupats seguint aquest esquema.

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1. The spatial and temporal abundance of the aphid Euceraphis betulae was investigated in relation to heterogeneity in host plant ( Betula pendula) vigour and pathogenic stress. The performance of aphids feeding on vigorous and stressed foliage was also examined. 2. The plant stress and plant vigour hypotheses have been suggested as opposing ways in which foliage quality influences herbivore abundance. In many plants, however, vigorous growing foliage co-exists with stressed or damaged foliage. 3. There was a negative correlation between branch growth ( vigour) and branch stress ( leaf chlorosis), with the most vigorous branches displaying little or no stress, and the most stressed branches achieving poor growth. There was a similar negative correlation between vigour and stress at the level of individual trees, which themselves represented a continuum in quality. 4. At the beginning of the season, E. betulae were intermittently more abundant on vigorous branches than on branches destined to become stressed, but aphids became significantly more abundant on stressed branches later in the season, when symptoms of stress became apparent. Similar patterns of aphid abundance were seen on vigorous and stressed trees in the following year. 5. Euceraphis betulae performance was generally enhanced when feeding on naturally stressed B. pendula leaves, but there was some evidence for elevated potential reproduction when feeding on vigorous leaves too. 6. Overall, plant stress probably influences E. betulae distribution more than plant vigour, but the temporal and spatial variability in plant quality suggests that plant vigour could play a role in aphid distribution early in the season.

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1Urban areas are predicted to grow significantly in the foreseeable future because of increasing human population growth. Predicting the impact of urban development and expansion on mammal populations is of considerable interest due to possible effects on biodiversity and human-wildlife conflict. 2The British government has recently announced a substantial housing programme to meet the demands of its growing population and changing socio-economic profile. This is likely to result in the construction of high-density, low-cost housing with small residential gardens. To assess the potential effects of this programme, we analysed the factors affecting the current pattern of use of residential gardens by a range of mammal species using a questionnaire distributed in wildlife and gardening magazines and via The Mammal Society. 3Twenty-two species/species groups were recorded. However, the pattern of garden use by individual species was limited, with only six species/species groups (bats, red fox Vulpes vulpes, grey squirrel Sciurus carolinensis, hedgehog Erinaceus europaeus, mice, voles) recorded as frequent visitors to > 20% of gardens in the survey. 4There was a high degree of association between the variables recorded in the study, such that it was difficult to quantify the effects of individual variables. However, all species/species groups appeared to be negatively affected by the increased fragmentation and reduced proximity of natural and semi-natural habitats, decreasing garden size and garden structure, but to differing degrees. Patterns of garden use were most clearly affected by house location (city, town, village, rural), with garden use declining with increasing urbanization for the majority of species/species groups, except red foxes and grey squirrels. Increasing urbanization is likely to be related to a wide range of interrelated factors, any or all of which may affect a range of mammal species. 5Overall, the probable effects of the planned housing development programme in Britain are not likely to be beneficial to mammal populations, although the pattern of use examined in this study may represent patterns of habitat selection by species rather than differences in distribution or abundance. Consequently, additional data are required on the factors affecting the density of species within urban environments.