1,019 research outputs found
Linearization of analytic and non--analytic germs of diffeomorphisms of
We study Siegel's center problem on the linearization of germs of
diffeomorphisms in one variable. In addition of the classical problems of
formal and analytic linearization, we give sufficient conditions for the
linearization to belong to some algebras of ultradifferentiable germs closed
under composition and derivation, including Gevrey classes.
In the analytic case we give a positive answer to a question of J.-C. Yoccoz
on the optimality of the estimates obtained by the classical majorant series
method.
In the ultradifferentiable case we prove that the Brjuno condition is
sufficient for the linearization to belong to the same class of the germ. If
one allows the linearization to be less regular than the germ one finds new
arithmetical conditions, weaker than the Brjuno condition. We briefly discuss
the optimality of our results.Comment: AMS-Latex2e, 11 pages, in press Bulletin Societe Mathematique de
Franc
Clinical significance of epithelial-to-mesenchymal transition in laryngeal carcinoma: Its role in the different subsites
Background: During epithelial-to-mesenchymal transition, cancer cells lose adhesion capacity gaining migratory properties. The role of the process on prognosis has been evaluated in 50 cases of laryngeal carcinoma. Methods: E-cadherin, N-cadherin, ÎČ-catenin, α-catenin, Îł-catenin, caveolin-1, and vimentin immunohistochemical expression were evaluated using a double score based on staining intensity and cellular localization. Results: Cytoplasmic E-cadherin and α/Îł catenin staining were associated with a decrease in survival, cytoplasmic ÎČ-catenin was associated with advanced stage, and N-cadherin and vimentin expression were associated with poor differentiation and tumor relapse. On the basis of cancer cells, epithelial or mesenchymal morphological and immunophenotypic similarity we identified 4 main subgroups correlated with a transition to a more undifferentiated phenotype, which have a different pattern of relapse and survival. Conclusion: The negative prognostic role of epithelial-to-mesenchymal transition has been confirmed and a predictive role in glottic tumors has been suggested, leading us to propose epithelial-to-mesenchymal transition as an additional adverse feature in laryngeal carcinoma
Digital humanities and crowdsourcing: an exploration
publication-status: PublishedâCrowdsourcingâ is a recent and evolving phenomenon, and the term has been broadly adopted to define different shades of public participation and contribution. Cultural institutions are progressively exploring crowdsourcing, and projectsâ related research is increasing. Nonetheless, few studies in the digital humanities have investigated crowdsourcing as a whole. The aim of this paper is to shed light on crowdsourcing practices in the digital humanities, thus providing insights to design new paths of collaboration between cultural organisations and their audiences. A web survey was carried out on 36 crowdsourcing projects promoted by galleries, libraries, archives, museums, and education institutions. A variety of practices emerged from the research. Even though, it seems that there is no âone-solution-fits-allâ for crowdsourcing in the cultural domain, few reflections are presented to support the development of crowdsourcing initiatives.Horizon Digital Economy Research Hu
Noisy continuous--opinion dynamics
We study the Deffuant et al. model for continuous--opinion dynamics under the
influence of noise. In the original version of this model, individuals meet in
random pairwise encounters after which they compromise or not depending of a
confidence parameter. Free will is introduced in the form of noisy
perturbations: individuals are given the opportunity to change their opinion,
with a given probability, to a randomly selected opinion inside the whole
opinion space. We derive the master equation of this process. One of the main
effects of noise is to induce an order-disorder transition. In the disordered
state the opinion distribution tends to be uniform, while for the ordered state
a set of well defined opinion groups are formed, although with some opinion
spread inside them. Using a linear stability analysis we can derive approximate
conditions for the transition between opinion groups and the disordered state.
The master equation analysis is compared with direct Monte-Carlo simulations.
We find that the master equation and the Monte-Carlo simulations do not always
agree due to finite-size induced fluctuations that we analyze in some detail
Noninvasive positive-pressure ventilation in acute respiratory distress syndrome: preliminary results
Emerging structures in social networks guided by opinionsâ exchanges
n this paper, we show that the small world and weak ties phenomena can spontaneously emerge in a social network of interacting agents. This dynamics is simulated in the framework of a simplified model of opinion diffusion in an evolving social network where agents are made to interact, possibly update their beliefs and modify the social relationships according to the opinion exchange
Scaling of the Critical Function for the Standard Map: Some Numerical Results
The behavior of the critical function for the breakdown of the homotopically
non-trivial invariant (KAM) curves for the standard map, as the rotation number
tends to a rational number, is investigated using a version of Greene's residue
criterion. The results are compared to the analogous ones for the radius of
convergence of the Lindstedt series, in which case rigorous theorems have been
proved. The conjectured interpolation of the critical function in terms of the
Bryuno function is discussed.Comment: 26 pages, 3 figures, 13 table
Isolation and genotyping of Acanthamoeba strains from corneal infections in Italy
Acanthamoeba keratitis (AK) is a corneal disease caused by members of a genus of free-living amoebae and is associated predominantly with contact lens (CL) use. This study reports 16 cases of culture-proven AK diagnosed in northern Italy. Genotype identification was carried out with a PCR assay based on sequence analysis of the 18S rRNA gene, and sensitivity and specificity were evaluated in comparison with traditional parasitological techniques. A 405â
bp region of the 18S rRNA gene (ASA.S1) including diagnostic fragment 3 (DF3) was amplified using the genus-specific primers JDP1 and JDP2. Genotype assignment was based on phenetic analysis of the ASA.S1 subset of the nuclear small-subunit rRNA gene sequence excluding the highly variable DF3 region. Phylogenetic analysis was also performed on the sequences obtained. All patients complained of monolateral infection; 11 (68.75%) admitted improper CL disinfection. In 14/16 (87.5â%) subjects, corneal scrapings were stained with calcofluor white and haematoxylin and eosin and, in ten cases (62.5â%), microscopy was positive for Acanthamoeba cysts. In vitro culture on 3â% non-nutrient agar plates was obtained in all cases (100â%), whereas cloning and axenic growth were positive for 14 amoebic stocks (87.5â%). PCR analysis had 100â% sensitivity and specificity compared with in vitro axenic culture, showing positive amplification from 15 isolates. All Acanthamoeba strains belonged to the T4 genotype, the main AK-related genotype worldwide. These results confirmed the importance of a complete diagnostic protocol, including a PCR assay, for the clinical diagnosis of AK on biological samples. Genotyping allowed inclusion of all isolates in the T4 group, thus demonstrating the prevalence of this genotype in northern Italy
Birth and Death in a Continuous Opinion Dynamics Model. The consensus case
We here discuss the process of opinion formation in an open community where
agents are made to interact and consequently update their beliefs. New actors
(birth) are assumed to replace individuals that abandon the community (deaths).
This dynamics is simulated in the framework of a simplified model that accounts
for mutual affinity between agents. A rich phenomenology is presented and
discussed with reference to the original (closed group) setting. Numerical
findings are supported by analytical calculations.Comment: 13 pages, 6 figure
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