We develop the theory of parton distributions f(_a)(π, k(^t2), μ(^2), unintegrated with respect to transverse momentum k(_t), from a phenomenological standpoint. In particular, we demonstrate a convenient approximation in which the unintegrated functions are obtained by explicitly performing the last step of parton evolution in perturbative QCD, with single-scale functions a(π, Q(^2) as input. Results are presented in the context of DGLAP and combined BFKL-DGLAP evolution, but with angular ordering imposed in the last step of the evolution. We illustrate the application of these unintegrated distributions to predict cross sections for physical processes at lepton-hadron and hadron-hadron colliders. The use of partons with incoming transverse momentum, based on k(_t)-factorisation, is intended to replace phenomenological "smearing" in the perturbative region k(_t) > k(_o) (k(_o) ≈ 1 GeV), and enables the full kinematics of a process to be included even at leading order. We apply our framework to deep inelastic scattering and the fitting of F(_2)(π, Q(^2), to the transverse momentum spectra of prompt photons in hadroproduction and in photoproduction, and to the topical problem of bb production at HERA. Finally, we address the issue of parton-parton recombination (shadowing) at very low values of π, building on recent work by Kovchegov and others to make predictions for the likely magnitude of shadowing effects at the LHC.

Submitted by Maria Eneide de Souza Araujo (mearaujo@ipen.br) on 2017-03-10T12:19:37Z No. of bitstreams: 1 22065.pdf: 2518783 bytes, checksum: e0f2e9eb82a52ecd6b57db50dcdac3fb (MD5) / Made available in DSpace on 2017-03-10T12:19:37Z (GMT). No. of bitstreams: 1 22065.pdf: 2518783 bytes, checksum: e0f2e9eb82a52ecd6b57db50dcdac3fb (MD5) / Muitos estudos têm sido realizados para determinar elementos essenciais nos alimentos, dentre eles o vinho, devido aos seus importantes papéis nutricionais em funções do corpo humano. Estudos apontam que o consumo diário e moderado de vinho contribui de forma significativa para as necessidades dos elementos essenciais para o corpo humano, tais como Ca, Co, Cr, Fe, K, Mg, Mn, Zn, V, entre outros, bem como traz benefícios para a saúde como a prevenção de inúmeras doenças e maior expectativa de vida, relacionados em particular com a ingestão de antioxidantes como os compostos polifenólicos. Por outro lado, outros elementos são bons indicadores da origem do vinho e as suas concentrações podem ser utilizadas como critério para garantir a autenticidade e a qualidade do vinho, bem como avaliar se os limites de tolerância estabelecidos pela lei foram respeitados durante todo o processo de produção. Todavia, embora a indústria do vinho no Brasil esteja entre as 15 maiores do mundo, ainda são poucos os estudos analíticos dos elementos no vinho se comparado a outros grandes produtores. Neste sentido este estudo teve como objetivo avaliar alguns procedimentos para preparação de amostras de vinho para determinar elementos essenciais por Análise por Ativação Neutrônica Instrumental (INAA) e comparar os resultados com a técnica de Espectrometria de Emissão Atômica por Plasma de Argônio Acoplado Indutivamente (ICP OES). Três procedimentos de preparação da amostra foram estudados: liofilização, evaporação e calcinação. Os parâmetros estudados foram precisão, exatidão e limite de detecção. Foram aplicados testes estatísticos de ANOVA e Tukey Kramer para verificar as diferenças estatísticas entre as médias obtidas pelos três procedimentos de preparação do vinho para INAA com as médias obtidas por ICP OES. Foi observado que cerca de 60% dos resultados obtidos por liofilização foram concordantes com aqueles obtidos por ICP OES. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Granular soils with different sizes and shapes are often used in many civil engineering structures. In different contexts, several researchers have emphasized that shape of particles play a pivotal role in influencing several engineering properties such as maximum and minimum packing densities, shear strength, permeability and compressibility. However, the complexities involved in obtaining the geometrical parameters necessary to adequately compute particle shape have hampered the clear understanding of the contribution of particle shape to such properties. Researchers have attempted to characterize the shape of the particles by many conventional and advanced image based methods in the past. However, these methods suffer from many criticisms; conventional methods of shape characterization include ocular inspection of particles based on visual reference charts, which are more prone to user dependent interpretations. The recently developed image based methods deviate from the conventional and most well accepted definitions formulated by researchers in the past due to the difficulties involved in automating them. The aim of this thesis is to address this shortcoming by developing a robust methodology for accurate and precise determination of particle shape in accordance with the most widely accepted formulae in literature, which can replace the existing methods based on manual measurements, approximate visual charts and non-robust imaging techniques. For this purpose, several computational algorithms are written and implemented in MATLAB and operations are performed on particle images. These methods are developed to precisely characterize the particles shape parameters observed at three levels of scales, which are adequate for complete shape characterization. According to Barrett (1980) the particle shape features can be observed independently at three different scales, viz. macro-scale, meso-scale and micro-scale, the shape parameters such as form, roundness and surface texture falls into these three scales respectively. The macro-scale component of form (sphericity) is quantified as per the formula used in the visual chart proposed by Krumbein & Sloss (1951). In light of its continuing popularity and wide usage, the roundness concept proposed by Wadell (1932) is chosen to be the appropriate parameter for meso-scale shape representation. The micro-scale component of surface texture or roughness is measured by the conventional and widely used root mean square definition, by incorporating the use of digital filtering techniques. The distinct concept of angularity as proposed by Lees (1964) is used for effective shape representation of crushed particles. Kinematic behaviour of particles such as sliding, rolling and interlocking are dependent on the geometrical features observed at meso-scale present along their boundaries, which consequently govern the material strength and deformation characteristics. Based on precise identification of such features (concavo-convex regions along particle boundary), a new classification chart is proposed in this thesis to comprehend the kinematics of particles. The effects of critical parameters such as scale, resolution and user defined cutoff values on the quantification of shape parameters are analyzed and eliminated. The proposed methodology is compared with standard visual charts provided by earlier researchers and is demonstrated on real soil particles falling across a wide range of sizes and shapes. Finally, the role of particle shape in governing packing behaviour of aggregates is quantified based on the precise particle shape characterization.

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