Regularization of energy-momentum tensor correlators and parity-odd terms

We discuss the problem of regularizing correlators in conformal field theories. The only way to do it in coordinate space is to interpret them as distributions. Unfortunately except for the simplest cases we do not have tabulated mathematical results. The way out we pursue here is to go to momentum space and use Feynman diagram techniques and their regularization methods. We focus on the energy-momentum tensor correlators and, to gain insight, we compute and regularize 2-point functions in 2d with various techniques both in coordinate space and in momentum space, obtaining the same results. Then we do the same for 2-point functions in 4d. Finally we turn to 3-point function in 4d, and concentrate on the parity-odd part. We derive in particular the regularized trace and divergence of the energy-momentum tensor in a chiral fermion model. We discuss the problems related to the parity-odd trace anomaly.Comment: 40 pages, 1 figure. v2: minor changes and typos correcte

From Strategic Planning to Development Initiatives: a first reflection on the situation of Lisbon and Barcelona

MARQUES, B.P. (2014) From Strategic Planning to Development Initiatives: a first reflection on the situation of Lisbon and Barcelona, in 20th APDR Congress Proceddings, APDR and UÉvora, Évora, pp. 850-857, ISBN 978-989-8780-01-0.Our object of study is a comparative analysis of local development processes on a metropolitan scale and our research focus are “city- regions” (cf. Scott, 1998; cf. Scott et al., 2002), understood as those metropolitan areas whose administrative and institutional boundaries do not always match with their political and economic identity and which are inserted in global processes of social and economic transformation. The main objectives of this work are the following: - Analyze and understand the competitive advantages that local and metropolitan political powers have in relation to Central State in creating favorable conditions for improving enterprises’ productivity and competitiveness; - Analyze new forms of democratic political participation, especially concerning territorial governance, in a global perspective of convergence between State and citizens interests; - Compare two different models of metropolitan organization and discuss its application to the Portuguese reality and, specifically, in Lisbon; - Reflect on the role of public policies and territorial strategic planning as support instruments for regional or local political powers, capable of promoting development in different metropolitan contexts; -Summarize the previously mentioned objectives throughout a comparative analysis between Lisbon and Barcelona metropolitan areas. Traditional planning processes, based on a normative spatial planning, continue to dominate the theories and practices of planning and promoting cities. Furthermore, even in territorial strategic planning, the emphasis is often placed in the realization of major cultural and sports events and the urban renewal of certain parts of cities. In this sense, the perspective that we want to carry out in this work will be more based on the promotion of local economic growth and will focus more on the analysis of strategic planning processes leading to local development initiatives in the fields of education, vocational training and entrepreneurship support, as opposed to a more “traditionalist” analysis of urban renewal and rehabilitation processes, in the perspective of what Peter Karl Kresel called “economic strategic planning” (cf. Kresel, 2007). Indeed, some theoretical approaches to regional and local development favor actions where municipalities interact and form alliances with other territorial actors (cf. Borja and Castells, 1997). Therefore, local political powers have gained considerable “leadership” in terms of economic growth and some authors talk about a “new type” of territorial management, designated by Ascher as “urban entrepreneurship”, by Harvey as “public urban management”, by Le Galès as “urban governing” or “local mercantilism” by Fainstein (cf. Salvador, 2006)

Local Development Initiatives: the case of São Paulo and ABCD Municipalities

MARQUES, B.P. (2008) “Local Development Initiatives: the case of São Paulo and ABCD Municipalities”, in Actas do 14.º Congresso da APDR, Tomar, pp. 253-279, ISBN 978-972-98803-9-1.It was only in 1930’s and, especially, in the 50’s, that São Paulo (and its Metropolitan Region) became the main industrial hub of Brazil. It was the “Plano de Metas” of President Juscelino Kubitschek that led to the introduction of mass manufacturing industries, with emphasis on the automobile industry, located in the southeast industrial periphery of São Paulo known as ABCD and corresponding to the municipalities of Santo André, São Bernardo do Campo, São Caetano do Sul, Diadema, Mauá, Ribeirão Pires and Rio Grande da Serra. São Paulo is the biggest city in Latin America and a “Global City”, nevertheless, it is also the “Metrópole das Desigualdades”, with a chaotic process of urbanization, a largely dilapidated housing and with high levels of poverty and social exclusion. With the oil crises, which occurred in the 70’s, the ABCD starts a process of productive restructuring that has led to some industries leaving the area. However, we believe that the conditions are met for the promotion of territorial development strategies based on local and endogenous factors, throughout measures where the local/regional political power interacts and establishes partnerships with other territorial actors: government, companies, financial institutions, business associations, cooperatives, non-governmental organizations and civic movements

Yahoo! : the end of the banner years

Yahoo! was in the late nineties the most profitable and successful internet company on the web. However, after the burst of the dotcom bubble, its competitive position changed dramatically as the banner advertising format, the center of its advertising-based business model, entered in decline. This dissertation uses dynamic capabilities to explain the failure of Yahoo! to respond to that change in the environment. For that purpose, we develop and analyze in detail a teaching case covering Yahoo!’s history from 1994 to 2007. As we succeed to explain the failure of Yahoo! as caused by a low level of dynamic capabilities, we conclude that the company had a low propensity to sense opportunities and threats, to make timely decisions and to make market-oriented decisions. We further identify problems in Yahoo!’s propensity to change its resource base that we classify as medium-low. Its low level of dynamic capabilities led Yahoo! to ignore the potential of search as a business and the emergence of keywords advertising as the dominant format of online advertising. Yahoo! reacted late and failed to transform its resource base in an effective manner to respond to those changes. These events still impact Yahoo!’s performance today

Caraterização termomecânica de adesivos estruturais a altas temperaturas

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáOs adesivos estruturais são amplamente utilizados na indústria civil, aeroespacial, automotiva, e outras aplicações de engenharia, devido à sua capacidade de unir materiais com propriedades distintas e proporcionar uma distribuição uniforme de tensões. No entanto, o desempenho desses adesivos pode ser severamente afetado em ambientes de alta temperatura, que pode afetar significativamente as propriedades mecânicas dos adesivos. Este trabalho tem como objetivo principal investigar o comportamento de adesivos estruturais, tolueno diisocianato (TDI) e do metileno difenil isocianato (MDI) quando expostos a altas temperaturas, aquecendo da temperatura ambiente até a degradação do adesivo. Foi realizado uma análise térmica utilizando um Analisador termomecânico - TMA 7100, por meio de testes de compressão e flexão, aplicando uma carga constante de valor mínimo a fim de apenas estar em contato com a amostra e registrar seu deslocamento, e uma variação de temperatura desde a temperatura ambiente até 400ºC. Análise mecânica dinâmica (DMA) foi realizada no mesmo equipamento com teste de compressão, alterando as condições de teste. A carga aplicada tem uma função senoidal com amplitude de 75mN, primeiro com as mesmas condições de aquecimento e posteriormente mantendo a temperatura constante em 100 e 200ºC durante o processo. Cada teste foi realizado em triplicata, para os dois tipos de adesivos. Os resultados obtidos através do TMA com os valores de transição vítrea () e temperatura de penetração (), em torno de 278ºC para o MDI e de 220ºC para o TDI, indicaram uma melhor resistência a altas temperaturas para o adesivo de MDI. Os resultados do DMA, por meio do módulo de elasticidade a 100ºC de 9,56 MPa para MDI e 0,98 MPa para TDI e, para 200ºC, 8,54 e 2,94 MPa para o MDI e TDI respectivamente. Esses valores indicam que o MDI é um material mais rígido em comparação ao TDI.Structural adhesives are widely used in civil, aerospace, automotive, and other engineering applications due to their ability to bond materials with distinct properties and provide evenly stress distribution. However, the performance of these adhesives can be severely affected in high temperature environments, which can significantly affect the adhesives' mechanical properties. The main purpose of this work is to investigate the behavior of structural adhesives, toluene diisocyanate (TDI) and methylene diphenyl isocyanate (MDI) when exposed to high temperatures, heating from room temperature to adhesive degradation. A thermal analysis was performed using a Thermomechanical analysis - TMA 7100, by means of compression and bending tests, applying a constant load of minimum value in order to only be in contact with the sample and register its displacement, and a temperature variation from room temperature up to 400ºC. Dynamic mechanical analysis (DMA) was performed in the same equipment with compression test, changing the test conditions. The applied load has a sine function with amplitude of 75mN, first with same of heating conditions and posteriorly keep a constant temperature of 100 and 200ºC during process. Each test was performed in triplicate for both adhesive types. The results obtained through TMA with the glass transition point () and penetration temperature () values, around 278ºC to MDI and 220ºC to TDI, indicated better high temperature resistance for the MDI adhesive. The DMA results, through modulus of elasticity at 100ºC of 9,56 MPa for MDI and 0,98 MPa for TDI, at 200ºC, 8,54 and 2,94 MPa for MDI and TDI respectively. These values indicate that MDI is a stiffer material compared to TDI

Polarization Charge Distribution in Gapped Graphene

We study the distribution of vacuum polarization charge induced by a Coulomb impurity in massive graphene. By analytically computing the polarization function, we show that the charge density is distributed in space in a non-trivial fashion, and on a characteristic length-scale set by the effective Compton wavelength. The density crosses over from a logarithmic behavior below this scale, to a power law variation above it. Our results in the continuum limit are confirmed by explicit diagonalization of the corresponding tight-binding model on a finite-size lattice. Electron-electron interaction effects are also discussed.Comment: 6 pages, 4 figures; expanded versio

Multiscale Fractal Descriptors Applied to Nanoscale Images

This work proposes the application of fractal descriptors to the analysis of nanoscale materials under different experimental conditions. We obtain descriptors for images from the sample applying a multiscale transform to the calculation of fractal dimension of a surface map of such image. Particularly, we have used the}Bouligand-Minkowski fractal dimension. We applied these descriptors to discriminate between two titanium oxide films prepared under different experimental conditions. Results demonstrate the discrimination power of proposed descriptors in such kind of application

Raman laser spectroscopy of Wannier Stark states

Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow 1D vertical lattice. For long enough laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atoms external degrees of freedom

Colagem e propriedades mecânicas da madeira de pinheiro tratada termicamente

O tratamento térmico da madeira permite diminuir a higroscopicidade da madeira, melhorando a sua estabilidade dimensional e a resistência a vários tipos de biodegradação. Utilizando este tratamento é possível atribuir um maior valor acrescentado, permitindo a madeiras menos nobres a sua utilização no exterior, sem a utilização de qualquer químico. O tratamento térmico da madeira de pinheiro (Pinus pinaster) foi feito na ausência de oxigénio numa autoclave com uma mistura de ar sobreaquecido e saturado durante 2, 4, 6, 8 e 12 horas à temperatura de 200 ºC. Determinou-se a resistência à colagem, a molhabilidade e a dureza nas secções tangencial e radial, o módulo de elasticidade e a tensão de rotura por flexão estática. A resistência à colagem, utilizando uma cola de acetato de polivinil (PVA) foi determinada de acordo com a norma DS/CEN/TS 13354. Determinou-se a molhabilidade da madeira pelo método do ângulo de contacto usando um goniómetro. A dureza foi medida de acordo com a norma ISO 3350 (1975). O módulo de elasticidade e a tensão de rotura à flexão foram determinados através de um ensaio a três pontos. Verificou-se que a resistência à colagem diminuiu com a intensidade do tratamento térmico. Foi possível obter uma relação aproximadamente linear (R2=0,81) entre a resistência à colagem e a perda de massa devido ao tratamento térmico. Ao mesmo tempo observou-se uma diminuição da molhabilidade da superfície da madeira o que contribui para uma diminuição da resistência à colagem. Em relação às propriedades mecânicas o MOE praticamente não foi afectado enquanto a tensão de rotura diminuiu com a intensidade do tratamento atingindo cerca de menos 30%. A dureza da madeira tratada também diminuiu quer na secção tangencial, quer na radial atingindo uma redução máxima de cerca de 30%