Search results for "Theorie"
showing 10 items of 354 documents
Non-perturbative renormalization of static-light four-fermion operators in quenched lattice QCD
2007
We perform a non-perturbative study of the scale-dependent renormalization factors of a multiplicatively renormalizable basis of $\Delta{B}=2$ parity-odd four-fermion operators in quenched lattice QCD. Heavy quarks are treated in the static approximation with various lattice discretizations of the static action. Light quarks are described by non-perturbatively ${\rm O}(a)$ improved Wilson-type fermions. The renormalization group running is computed for a family of Schroedinger functional (SF) schemes through finite volume techniques in the continuum limit. We compute non-perturbatively the relation between the renormalization group invariant operators and their counterparts renormalized in …
Hyperboloidal slicing approach to quasinormal mode expansions: The Reissner-Nordström case
2018
We study quasi-normal modes of black holes, with a focus on resonant (or quasi-normal mode) expansions, in a geometric frame based on the use of conformal compactifications together with hyperboloidal foliations of spacetime. Specifically, this work extends the previous study of Schwarzschild in this geometric approach to spherically symmetric asymptotically flat black hole spacetimes, in particular Reissner-Nordstr\"om. The discussion involves, first, the non-trivial technical developments needed to address the choice of appropriate hyperboloidal slices in the extended setting as well as the generalization of the algorithm determining the coefficients in the expansion of the solution in te…
General interpolation scheme for thermal fluctuations in superconductors
2006
We present a general interpolation theory for the phenomenological effects of thermal fluctuations in superconductors. Fluctuations are described by a simple gauge invariant extension of the gaussian effective potential for the Ginzburg-Landau static model. The approach is shown to be a genuine variational method, and to be stationary for infinitesimal gauge variations around the Landau gauge. Correlation and penetration lengths are shown to depart from the mean field behaviour in a more or less wide range of temperature below the critical regime, depending on the class of material considered. The method is quite general and yields a very good interpolation of the experimental data for very…
Advanced models for nonlocal magneto-electro-elastic multilayered plates based on Reissner mixed variational theorem
2019
In the present work, nonlocal layer-wise models for the analysis of magneto-electro-elastic multilayered plates are formulated. An Eringen non-local continuum behaviour is assumed for the layers material; in particular, as usual in plate theories, partial in-plane nonlocality is assumed whereas local constitutive behaviour is considered in the thickness direction. The proposed plate theories are obtained via the Reissner Mixed Variational Theorem, assuming the generalized displacements and generalized out-of-plane stresses as primary variables, and expressing them as through-the-thickness expansions of suitably selected functions, considering the expansion order as a free parameter. In the …
Light majoron cold dark matter from topological defects and the formation of boson stars
2019
We show that for a relatively light majoron ($\ll 100 $ eV) non-thermal production from topological defects is an efficient production mechanism. Taking the type I seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. The latter is consistent with the scale of unification. Possible direct detection of light majorons with future experiments such as PTOLEMY and the formation of boson stars from the majoron dark matter are also discussed.
SEA presidential address: Group connectivity and cooperation
2011
A model-free methodology is used for the first time to estimate a daily volatility index (VIBEX-NEW) for the Spanish financial market.We use a public data set of daily option prices to compute this index and showthat daily changes in VIBEXNEW display a negative, tight contemporaneous relationship with IBEX daily returns, contrary to other common volatility indicators, as an implied volatility indicator or a GARCH(1,1) conditional volatility model. This relationship is approximately symmetric to the sign on VIBEX-NEW changes and asymmetric to the IBEX-35 returns sign, which make it clearly a suitable volatility index for the Spanish stock market. We also examine the relationship between curr…
Street Names through Sociological Lenses. Part I: Functionalism and Conflict Theory
2020
Abstract Street names are mundane spatial markers that besides providing a sense of orientation inscribe onto the landscape the ideological ethos and political symbols of hegemonic discourses. This review article takes stock of the existing scholarship done on the politics of street naming practices in human (political, cultural, and social) geography and rethinks these insights from sociological perspectives. Drawing on Randall Collins’ taxonomy of sociological theory, the paper interprets urban street nomenclatures along functionalist, conflictualist, constructionist, and utilitarian lines. The analysis is delivered in two installments: Part I addresses urban nomenclatures from functional…
The Rocky Road towards Professional Autonomy : The Estonian Journalists’ Organization in the Political Turmoil of the 20th Century
2017
This article attempts to explain the relationships between journalists, politics and the state from the perspective of collective autonomy, that of the professional organization of journalists. The case of Estonian Journalists’ Union demonstrates the complexity and historical contingency of professional autonomy of journalism. The development of the Estonian journalists’ organization occurred as a sequence of transformations from the Estonian Journalists’ Association to the Estonian Journalists’ Union to the Soviet type journalists’ union, and lastly to an independent trade union. This sequence was disrupted by several fatal breakdowns that changed not only the character of the association,…
A review of the neurobiological basis of dyslexia in the adult population
2017
Introduction: Adult dyslexia affects about 4% of the population. However, studies on the neurobiological basis of dyslexia in adulthood are scarce compared to paediatric studies. Aim: This review investigates the neurobiological basis of dyslexia in adulthood. Development: Using PsycINFO, a database of psychology abstracts, we identified 11 studies on genetics, 9 neurostructural studies, 13 neurofunctional studies and 24 neurophysiological studies. Results from the review show that dyslexia is highly heritable and displays polygenic transmission. Likewise, adult neuroimaging studies found structural, functional, and physiological changes in the parieto-occipital and occipito-temporal region…
Localizing the politics of privacy in communication and media research
2020
While previous communication and media research has largely focused on either studying privacy as personal boundary management or made efforts to investigate the structural (legal or economic) condition of privacy, we observe an emergent body of research on the political underpinnings of privacy linking both aspects. A pronounced understanding of the politics of privacy is however lacking. In this contribution, we set out to push this forward by mapping four communication and media perspectives on the political implications of privacy. In order to do so, we recur on Barry’s (2002) distinction of the political and the politics and outline linkages between individual and structural dimensions…