Implementation science

Vol. 11, num. 152, p. 1-7

DOI: 10.1186/s13012-016-0522-3

Date of publication: 2016-11-24

Abstract:

Background: Influenza vaccination coverage remains low among health care workers (HCWs) in many health facilities. This study describes the social network defined by HCWs’ conversations around an influenza vaccination campaign in order to describe the role played by vaccination behavior and other HCW characteristics in the configuration of the links among subjects. Methods This study used cross-sectional data from 235 HCWs interviewed after the 2010/2011 influenza vaccination campaign at the Hospital Clinic of Barcelona (HCB), Spain. The study asked: “Who did you talk to or share some activity with respect to the seasonal vaccination campaign?” Variables studied included sociodemographic characteristics and reported conversations among HCWs during the influenza campaign. Exponential random graph models (ERGM) were used to assess the role of shared characteristics (homophily) and individual characteristics in the social network around the influenza vaccination campaign. Results Links were more likely between HCWs who shared the same professional category (OR 3.13, 95% CI¿=¿2.61–3.75), sex (OR 1.34, 95% CI¿=¿1.09–1.62), age (OR 0.7, 95% CI¿=¿0.63–0.78 per decade of difference), and department (OR 11.35, 95% CI¿=¿8.17–15.64), but not between HCWs who shared the same vaccination behavior (OR 1.02, 95% CI¿=¿0.86–1.22). Older (OR 1.26, 95% CI¿=¿1.14–1.39 per extra decade of HCW) and vaccinated (OR 1.32, 95% CI¿=¿1.09–1.62) HCWs were more likely to be named. Conclusions This study finds that there is no homophily by vaccination status in whom HCWs speak to or interact with about a workplace vaccination promotion campaign. This result highlights the relevance of social network analysis in the planning of health promotion interventions.]]>

Zeitschrift für Naturforschung. Section A, a journal of physical sciences

Vol. 71, num. 10, p. 897-907

DOI: 10.1515/zna-2016-0079

Date of publication: 2016-10-10

Abstract:

Floquet theory provides rigorous foundations for the theory of periodically driven quantum systems. In the case of non-periodic driving, however, the situation is not so well understood. Here, we provide a critical review of the theoretical framework developed for quasi-periodically driven quantum systems. Although the theoretical footing is still under development, we argue that quasi-periodically driven quantum systems can be treated with generalisations of Floquet theory in suitable parameter regimes. Moreover, we provide a generalisation of the Floquet-Magnus expansion and argue that quasi-periodic driving offers a promising route for quantum simulations.]]>

Abstract:

This project belongs to the area of Dynamical Systems and Applications, and it is the natural continuation of projects MTM2006-00478, MTM2009-06973 and MTM2012-31714, focusing on the local study and, mainly, the global study of continuous and discrete dynamical systems using analytical and numerical tools. The Dynamical Systems Group at the UPC is broad and interdisciplinary, combining experienced researchers with young researchers. This high research potential, coupled with a solid theoretical base, makes it possible to cover a wide set of classic and new problems in Dynamical Systems. The goal of the project consists on keep our leadership in the areas of Arnold Diffusion, splitting of separatrices and Astrodynamics, as well as advance in the study of bifurcations, computation of invariant objects and integrability. But we also want to strengthen the application of Dynamical Systems tools to problems in Astrodynamics, Celestial Mechanics, Chemistry and, as was most recently done with great success, in infinite dimensional Dynamical Systems and Neuroscience. In order to obtain numerical results not only in some theoretical problems, like exponentially small splitting of separatrices, but also in applications to Astrodynamics, Celestial Mechanics or Neuroscience, a highly computational approach is necessary, and very often it is only possible through parallel computation (the group owns and maintains a HPC cluster). The group already has a widely recognized expertise and prestige in these fields, and we plan to continue working on them in the following years Finally, it is important to stress that the group seeks a balance between working on issues where it is already expert and internationally recognized, and do it in new and more challenging problems for the group, such as infinite dimensional Dynamical Systems and Neuroscience. Our goals for the next three years are the following: A. Arnold Diffusion A.1. A-priori unstable Systems. A.2. A-priori stable Systems. A.3. Applications. B. Exponentially small phenomena B.1. Splitting of separatrices to low dimensional invariant objects. B.2. Splitting of separatrices in the Hopf-zero singularity. B.3. Using Melnikov potential in the problem of splitting of separatrices. B.4. Billiards next to the boundary. C. Integrability C.1. Planar polinomial vector fields. C.2. Algebraic integrable systems. D. Invariant objects and their bifurcations D.1. Invariant manifold of parabolic objects. D.2. Filippov Systems. D.3.Planar reversible diffeomorphisms. D.4. Planar vector fields. D.5. Quasi- periodic dynamics. D.6. Applications. E. Infinite Dimensional Dynamical Systems. E.1. Growth of Sobolev norms in Hamiltonian PDEs. E.2.Singular problems in PDEs. F. Astrodynamics F.1. Generation of natural and artificial trajectories. F.2. Artificial satellite formation. F.3. Analysis of orbits in the three body problem. G. Neuroscience and Biomedical applications G.1. Dynamics of models for single neurons and neural populations. G.2. Biomedical applications.]]>

Nonlinearity

Vol. 26, num. 5, p. 1163-1187

DOI: 10.1088/0951-7715/26/5/1163

Date of publication: 2013-05

Abstract:

In this paper, we study the dynamical properties of a class of ergodic linear skew-products which includes the linear skew-products defined by quasi-periodic Schrodinger operators and their duals, in Aubry sense, when the potential is a trigonometric polynomial. Notably, these linear skew-products preserve an adapted complex-symplectic structure. We prove a Thouless formula relating the sum of the positive Lyapunov exponents and the logarithmic potential associated with the density of states of the corresponding operator. In particular, for quasi-periodic Schrodinger operators and their duals, we prove an identity for the upper Lyapunov exponent of the skew-product and the sum of the positive Lyapunov exponents of their dual, which generalizes the well-known formula for the Almost Mathieu. We illustrate these identities with some numerical illustrations.]]>

PloS one

Vol. 7, num. 7, p. e39496-e39500

DOI: 10.1371/journal.pone.0039496

Date of publication: 2012-07

Abstract:

Published influenza vaccination coverage in health care workers (HCW) are calculated using two sources: self-report and vaccination records. The objective of this study was to determine whether self-report is a good proxy for recorded vaccination in HCW, as the degree of the relationship is not known, and whether vaccine behaviour influences self-reportin]]>

Date of publication: 2011-09

Journal of dynamics and differential equations

Vol. 23, num. 1, p. 61-78

DOI: 10.1007/s10884-010-9199-5

Date of publication: 2011-01-04

Regular and chaotic dynamics

Vol. 16, num. 1-2, p. 62-79

DOI: 10.1134/S1560354710520047

Date of publication: 2011

Abstract:

n this article we investigate numerically the spectrum of some representative examples of discrete one-dimensional Schrödinger operators with quasi-periodic potential in terms of a perturbative constant b and the spectral parameter a. Our examples include the well-known Almost Mathieu model, other trigonometric potentials with a single quasi-periodic frequency and generalisations with two and three frequencies. We computed numerically the rotation number and the Lyapunov exponent to detect open and collapsed gaps, resonance tongues and the measure of the spectrum. We found that the case with one frequency was significantly different from the case of several frequencies because the latter has all gaps collapsed for a sufficiently large value of the perturbative constant and thus the spectrum is a single spectral band with positive Lyapunov exponent. In contrast, in the cases with one frequency considered, gaps are always dense in the spectrum, although some gaps may collapse either for a single value of the perturbative constant or for a range of values. In all cases we found that there is a curve in the (a, b)-plane which separates the regions where the Lyapunov exponent is zero in the spectrum and where it is positive. Along this curve, which is b = 2 in the Almost Mathieu case, the measure of the spectrum is zero.]]>

Date: 2010-07

Abstract:

Abstract. In this paper we investigate numerically the spectrum of some representative examples of discrete one-dimensional Schr¨odinger operators with quasi-periodic potential in terms of a perturbative constant b and the spectral parameter a. Our examples include the well-known Almost Mathieu model, other trigonometric potentials with a single quasi-periodic frequency and generalisations with two and three frequencies. We computed numerically the rotation number and the Lyapunov exponent to detect open and collapsed gaps, resonance tongues and the measure of the spectrum. We found that the case with one frequency was significantly different from the case of several frequencies because the latter has all gaps collapsed for a sufficiently large value of the perturbative constant and thus the spectrum is a single spectral band with positive Lyapunov exponent. In contrast, in the cases with one frequency considered, gaps are always dense in the spectrum, although some gaps may collapse either for a single value of the perturbative constant or for a range of values. In all cases we found that there is a curve in the (a, b)-plane which separates the regions where the Lyapunov exponent is zero in the spectrum and where it is positive. Along this curve, which is b = 2 in the Almost Mathieu case, the measure of the spectrum is zero.]]>

Date: 2010-07

Abstract:

In this paper we investigate numerically the following Hill’s equation x00 + (a + bq(t))x = 0 where q(t) = cos t + cosp2t + cosp3t is a quasiperiodic forcing with three rationally independent frequencies. It appears,also, as the eigenvalue equation of a Schr¨odinger operator with quasi-periodic potential. Massive numerical computations were performed for the rotation number and the Lyapunov exponent in order to detect open and collapsed gaps, resonance tongues. Our results show that the quasi-periodic case with three independent frequencies is very different not only from the periodic analogs, but also from the case of two frequencies. Indeed, for large values of b the spectrum contains open intervals at the bottom. From a dynamical point of view we numerically give evidence of the existence of open intervals of a, for large b where the system is nonuniformly hyperbolic: the system does not have an exponential dichotomy but the Lyapunov exponent is positive. In contrast with the region with zero Lyapunov exponents, both the rotation number and the Lyapunov exponent do not seem to have square root behavior at endpoints of gaps. The rate of convergence to the rotation number and the Lyapunov exponent in the nonuniformly hyperbolic case is also seen to be different from the reducible case.]]>

Date of publication: 2009-02

Vol. 15, num. 3

XI Trobada de la Societat Catalana de Matemàtiques

Presentation's date: 2008-06-06

Conference on Stability and Instability in Mechanical Sysyems: Recent Progress and Mathematical Theory

NoLineal 2008

p. 164

International Symposium: The Frontiers of Mathematics

Presentation's date: 2007-06-07

Workshop on Dynamics of Nonlinear Waves

Presentation's date: 2007-04-24

Workshop on Strange Nonchaotic Attractors

Presentation's date: 2007-03-28

I Iberian Mathematical Meeting

Presentation's date: 2007-02-09

Communications in mathematical physics

Vol. 267, num. 3, p. 481-524

Date of publication: 2006-11

Chaos : an interdisciplinary journal of nonlinear science

Vol. 16, num. 3, p. 127-134

Date of publication: 2006-09

Ergodic theory and dynamical systems

Vol. 26, num. 2, p. 481-524

Date of publication: 2006-04

Date of publication: 2006-04

Boletín de la Sociedad Española de Matemática Aplicada

Vol. 34, p. 118-123

Date of publication: 2006-03

Nonlinearity

Vol. 19, num. 2, p. 355-376

Date of publication: 2006-02

Oberwolfach reports

Vol. 2, num. 4

Date of publication: 2005-11

Congreso de Ecuaciones Diferenciales y Aplicaciones / Congreso de Matemática Aplicada

Presentation's date: 2005-09-19

Newsletter of the European Mathematical Society

Vol. 57, p. 165-188

Date of publication: 2005-09

Date of publication: 2005-04

Date: 2005-03

Congreso MAT.ES (RSME-SCM-SEIO-SEMA)

Presentation's date: 2005-02-01

Curs Einstein (2004-2005)

p. 1-16

Congreso de Ecuaciones Diferenciales y Aplicaciones / Congreso de Matemática Aplicada

p. 118-123

Congreso de Ecuaciones Diferenciales y Aplicaciones / Congreso de Matemática Aplicada

p. 41

Dynamics of Cocycles and One-Dimensional Spectral Theory

p. 2937-2939

Journée Dynamique de l'Institut de Mathématiques de Jussieu

Presentation's date: 2004-12-03

Nonlinear Dynamics, Ergodic Theory and Renormalization

Presentation's date: 2004-09-20

Spectral Theory of Schrodinger Operators

Presentation's date: 2004-07-26

110th Annual Meeting of the American Mathematical Society

Presentation's date: 2004-01-07