875 resultados para Superlinear and Semi–Superlinear Convergence
Resumo:
Since the 1990s, and especially since the early 2000s, passionate controversies (Göle 2014) have emerged around the new visibility of Islam in the public sphere across Europe. These controversies, which crystallized in the headscarf debate, seem even more disturbing given that women who wear it are often young, urban and educated: that is to say, "modern" (Göle 1997, 2011). Indeed, these young women wearing the hijab seem to disrupt the narrative of Western modernity, including the decline in religious practice (Hervieu-Léger 2006) or the narration of the process of secularization in Europe. It is in the context of these controversies that Islam is built imaginatively as a "public problem" that has to be "solved" (Behloul 2012). Thus, this social construction of the Muslim other has nurtured an assessment of the failure of multiculturalism in some European countries and a process of convergence around a single model of civic integration in Europe (Behloul 2012, Joppke 2004, 2010).
Resumo:
This article contributes to the ongoing debate on the economic deter- minants of fertility behavior by addressing the role of job insecurity in couples' intentions concerning parenthood and its timing. It starts from the hypothesis that cultural values moderate individuals' reactions to job insecurity and the way it is related to family formation. With a systematic thematic content analysis of a set of semi-structured interviews with childless men and women around the age of 30 in eastern and western Germany, we are able to show that there are substantial dif- ferences in the consequences of job insecurity on intentions to have a first child. In western Germany, a relatively secure job career is expected to precede family formation, and this sequence of transitions is rather rigid, whereas in eastern Germany job security and family formation are thought of and practiced as parallel investments. We suggest that the lack of convergence in family formation patterns between eastern and western Germany after the unification of the country in 1990 is partially related to different attitudes toward job insecurity in the two contexts.
Resumo:
OBJECTIVE:: The study of HIV-1 rapid progressors has been limited to specific case reports. Nevertheless, identification and characterization of the viral and host factors involved in rapid progression are crucial when attempting to uncover the correlates of rapid disease outcome. DESIGN:: We carried out comparative functional analyses in rapid progressors (n = 46) and standard progressors (n = 46) early after HIV-1 seroconversion (≤1 year). The viral traits tested were viral replicative capacity, co-receptor usage, and genomic variation. Host CD8 T-cell responses, humoral activity, and HLA immunogenetic markers were also determined. RESULTS:: Our data demonstrate an unusual convergence of highly pathogenic HIV-1 strains in rapid progressors. Compared with standard progressors, rapid progressor viral strains show higher in-vitro replicative capacity (81.5 vs. 67.9%; P = 0.025) and greater X4/DM co-receptor usage (26.3 vs. 2.8%; P = 0.006) in early infection. Limited or absent functional HIV-1 CD8 T-cell responses and neutralizing activity were measured in rapid progressors. Moreover, the increase in common HLA allele-restricted CD8 T-cell escape mutations in rapid progressors acts as a signature of uncontrolled HIV-1 replication and early impairment of adaptive cellular responses. CONCLUSION:: Our data support a dominant role for viral factors in rapid progressors. Robust HIV-1 replication and intrinsic viral properties limit host adaptive immune responses, thus driving rapid disease progression.
Resumo:
Peroxisome proliferator-activated receptor (PPARs) are members of the nuclear receptor superfamily. For transcriptional activation of their target genes, PPARs heterodimerize with the retinoid-X receptor (RXR). The convergence of the PPAR and RXR signaling pathways has been shown to have an important function in lipid metabolism. The promoter of the gene encoding the acyl-coenzyme-A oxidase (ACO), the rate-limiting enzyme in peroxisomal beta-oxidation of fatty acids, is a target site of PPAR action. In this study, we examined the role and the contribution of both cis-and trans-acting factors in the transcriptional regulation of this gene using transient transfections in insect cells. We identified several functional cis-acting elements present in the promoter of the ACO gene and established that PPAR-dependent as well as PPAR-independent mechanisms can activate the ACO promoter in these cells. We show that the PPAR/RXR heterodimer exerts its effect through two response elements within the ACO promoter, in synergy with the transcription factor Sp1 via five Sp1-binding sites. Furthermore, this functional interaction also occurs when Sp1 is co-expressed with PPAR or RXR alone, indicating that activation can occur independently of PPAR/RXR heterodimers.
Resumo:
First: A continuous-time version of Kyle's model (Kyle 1985), known as the Back's model (Back 1992), of asset pricing with asymmetric information, is studied. A larger class of price processes and of noise traders' processes are studied. The price process, as in Kyle's model, is allowed to depend on the path of the market order. The process of the noise traders' is an inhomogeneous Lévy process. Solutions are found by the Hamilton-Jacobi-Bellman equations. With the insider being risk-neutral, the price pressure is constant, and there is no equilibirium in the presence of jumps. If the insider is risk-averse, there is no equilibirium in the presence of either jumps or drifts. Also, it is analised when the release time is unknown. A general relation is established between the problem of finding an equilibrium and of enlargement of filtrations. Random announcement time is random is also considered. In such a case the market is not fully efficient and there exists equilibrium if the sensitivity of prices with respect to the global demand is time decreasing according with the distribution of the random time. Second: Power variations. it is considered, the asymptotic behavior of the power variation of processes of the form _integral_0^t u(s-)dS(s), where S_ is an alpha-stable process with index of stability 0&alpha&2 and the integral is an Itô integral. Stable convergence of corresponding fluctuations is established. These results provide statistical tools to infer the process u from discrete observations. Third: A bond market is studied where short rates r(t) evolve as an integral of g(t-s)sigma(s) with respect to W(ds), where g and sigma are deterministic and W is the stochastic Wiener measure. Processes of this type are particular cases of ambit processes. These processes are in general not of the semimartingale kind.
Resumo:
Malgrat els esforços de la UE en la promoció de la democràcia i un compromís comú per la democràcia i els drets humans al EMP, no hi ha signes de convergència cap al model liberal democràtic propugnat per la UE. No obstant això, l'abast i la intensitat de la cooperació multilateral, transnacional i bilateral han augmentat constantment en tota la regió des de mitjans de 1990. La cooperació en el camp de la promoció de la democràcia es caracteritza per la forta dinàmica de normativa sectorial, i la diferenciació geogràfica, però està clarament situada en un marc regional i altament estandarditzat. Si bé la convergència política o la política sembla poc probable en el curt o mitjà termini, democràcia i drets humans estan fermament establerts en una agenda regional comú
Resumo:
The publishing industry is at a turning point. Facing the first major disruptive innovation in five centuries, its long-established structure and business model are at stake. Building on literature based on the pitfalls for incumbents, we interviewed key executives from the major publishers in Brazil to understand their perspective. We find that not only are they facing those pitfalls, but we also propose a new one, The Industry View Trap, concerning challenges created by convergence, the difficulty to deal with changes in the ecosystem and the fact that the very definition of the industry you're part of might have changed.
Resumo:
The information and communication technologies (ICT) sectors are in a process of technological convergence. Determinant factors in this process are the liberalisation of the telecommunications markets and technological change. Many firms are engaged in a process of mergers and alliances to position themselves in this new framework. Technological and demand uncertainties are very important. Our objective in this paper is to study the economic determinants of the strategies of the firms. With this aim, we review some key technological and demand aspects. We shed some light on the strategic motivations of the firms by establishing a parallel with the evolution of the retailing sector
Resumo:
The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome is a multiprotein complex that activates caspase 1, leading to the processing and secretion of the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and IL-18. The NLRP3 inflammasome is activated by a wide range of danger signals that derive not only from microorganisms but also from metabolic dysregulation. It is unclear how these highly varied stress signals can be detected by a single inflammasome. In this Opinion article, we review the different signalling pathways that have been proposed to engage the NLRP3 inflammasome and suggest a model in which one of the crucial elements for NLRP3 activation is the generation of reactive oxygen species (ROS).
Resumo:
Selected configuration interaction (SCI) for atomic and molecular electronic structure calculations is reformulated in a general framework encompassing all CI methods. The linked cluster expansion is used as an intermediate device to approximate CI coefficients BK of disconnected configurations (those that can be expressed as products of combinations of singly and doubly excited ones) in terms of CI coefficients of lower-excited configurations where each K is a linear combination of configuration-state-functions (CSFs) over all degenerate elements of K. Disconnected configurations up to sextuply excited ones are selected by Brown's energy formula, ΔEK=(E-HKK)BK2/(1-BK2), with BK determined from coefficients of singly and doubly excited configurations. The truncation energy error from disconnected configurations, Δdis, is approximated by the sum of ΔEKS of all discarded Ks. The remaining (connected) configurations are selected by thresholds based on natural orbital concepts. Given a model CI space M, a usual upper bound ES is computed by CI in a selected space S, and EM=E S+ΔEdis+δE, where δE is a residual error which can be calculated by well-defined sensitivity analyses. An SCI calculation on Ne ground state featuring 1077 orbitals is presented. Convergence to within near spectroscopic accuracy (0.5 cm-1) is achieved in a model space M of 1.4× 109 CSFs (1.1 × 1012 determinants) containing up to quadruply excited CSFs. Accurate energy contributions of quintuples and sextuples in a model space of 6.5 × 1012 CSFs are obtained. The impact of SCI on various orbital methods is discussed. Since ΔEdis can readily be calculated for very large basis sets without the need of a CI calculation, it can be used to estimate the orbital basis incompleteness error. A method for precise and efficient evaluation of ES is taken up in a companion paper
Resumo:
To obtain a state-of-the-art benchmark potential energy surface (PES) for the archetypal oxidative addition of the methane C-H bond to the palladium atom, we have explored this PES using a hierarchical series of ab initio methods (Hartree-Fock, second-order Møller-Plesset perturbation theory, fourth-order Møller-Plesset perturbation theory with single, double and quadruple excitations, coupled cluster theory with single and double excitations (CCSD), and with triple excitations treated perturbatively [CCSD(T)]) and hybrid density functional theory using the B3LYP functional, in combination with a hierarchical series of ten Gaussian-type basis sets, up to g polarization. Relativistic effects are taken into account either through a relativistic effective core potential for palladium or through a full four-component all-electron approach. Counterpoise corrected relative energies of stationary points are converged to within 0.1-0.2 kcal/mol as a function of the basis-set size. Our best estimate of kinetic and thermodynamic parameters is -8.1 (-8.3) kcal/mol for the formation of the reactant complex, 5.8 (3.1) kcal/mol for the activation energy relative to the separate reactants, and 0.8 (-1.2) kcal/mol for the reaction energy (zero-point vibrational energy-corrected values in parentheses). This agrees well with available experimental data. Our work highlights the importance of sufficient higher angular momentum polarization functions, f and g, for correctly describing metal-d-electron correlation and, thus, for obtaining reliable relative energies. We show that standard basis sets, such as LANL2DZ+ 1f for palladium, are not sufficiently polarized for this purpose and lead to erroneous CCSD(T) results. B3LYP is associated with smaller basis set superposition errors and shows faster convergence with basis-set size but yields relative energies (in particular, a reaction barrier) that are ca. 3.5 kcal/mol higher than the corresponding CCSD(T) values
Resumo:
Initial convergence of the perturbation series expansion for vibrational nonlinear optical (NLO) properties was analyzed. The zero-point vibrational average (ZPVA) was obtained through first-order in mechanical plus electrical anharmonicity. Results indicated that higher-order terms in electrical and mechanical anharmonicity can make substantial contributions to the pure vibrational polarizibility of typical NLO molecules
Resumo:
The article presents and discusses estimates of social and economic indicators for Italy’s regions in benchmark years roughly from Unification to the present day: life expectancy, education, GDP per capita at purchasing power parity, and the new Human Development Index (HDI). A broad interpretative hypothesis, based on the distinction between passive and active modernization, is proposed to account for the evolution of regional imbalances over the long-run. In the lack of active modernization, Southern Italy converged thanks to passive modernization, i.e., State intervention: however, this was more effective in life expectancy, less successful in education, expensive and as a whole ineffective in GDP. As a consequence, convergence in the HDI occurred from the late XIX century to the 1970s, but came to a sudden halt in the last decades of the XX century.
Resumo:
In this paper we attempt to describe the general picture reasons behind the world population explosion during the 20th century. In general we comment that if, according to some, at the end of the 20th century there were too many people, this was has a consequence of scientific innovation, circulation of information, and economic growth, leading to a dramatic improvement in life expectancies. Nevertheless, a crucial variable shaping differences in demographic growth is fertility. In this paper we identify as important exogenous variables affecting fertility female education levels, infant mortality, and racial identity and diversity. It is estimated that three additional years of schooling for mothers leads on average (at the world level ) to one child less per couple. Even if we can identify a worldwide trend towards convergence in demographic trends, the African case needs to be given more attention, not only because of its different demographic patterns, but also because this is the continent where the worldwide movement towards a higher quality of life has not yet been achieved for an important share of the world's population.
Resumo:
Evidence of multisensory interactions within low-level cortices and at early post-stimulus latencies has prompted a paradigm shift in conceptualizations of sensory organization. However, the mechanisms of these interactions and their link to behavior remain largely unknown. One behaviorally salient stimulus is a rapidly approaching (looming) object, which can indicate potential threats. Based on findings from humans and nonhuman primates suggesting there to be selective multisensory (auditory-visual) integration of looming signals, we tested whether looming sounds would selectively modulate the excitability of visual cortex. We combined transcranial magnetic stimulation (TMS) over the occipital pole and psychophysics for "neurometric" and psychometric assays of changes in low-level visual cortex excitability (i.e., phosphene induction) and perception, respectively. Across three experiments we show that structured looming sounds considerably enhance visual cortex excitability relative to other sound categories and white-noise controls. The time course of this effect showed that modulation of visual cortex excitability started to differ between looming and stationary sounds for sound portions of very short duration (80 ms) that were significantly below (by 35 ms) perceptual discrimination threshold. Visual perceptions are thus rapidly and efficiently boosted by sounds through early, preperceptual and stimulus-selective modulation of neuronal excitability within low-level visual cortex.