0000000000357982
AUTHOR
Francisco Morillas
Attractors for non-autonomous retarded lattice dynamical systems
AbstractIn this paperwe study a non-autonomous lattice dynamical system with delay. Under rather general growth and dissipative conditions on the nonlinear term,we define a non-autonomous dynamical system and prove the existence of a pullback attractor for such system as well. Both multivalued and single-valued cases are considered.
Procedures for Antibiotic Residues in Bovine Muscle Tissues
Abstract Acetonitrile extraction followed by primary-secondary amine dispersive SPE cleanup QuEChERS (quick, easy, cheap, effective, rugged, and safe), was compared to pressurized liquid extraction (PLE) using water at 70°C for 10 min at 1500 psi for the determination of 16 veterinary drugs in bovine muscle tissues by LC/MS/MS. PLE was significantly more effective for the extraction of veterinary drugs (ranging from 69 to 103% with RSD ≤ 18%) than QuEChERS (ranging from 19 to 89% with RSD ≤ 19%). Linearity of the calibration curves was obtained over the range considered (from 10 μg/kg or LOQ to 1000, μg/kg) with r2 ≥ 0.99 for all the analytes by both methods. Although an internal standard w…
Random attractors for stochastic lattice systems with non-Lipschitz nonlinearity
In this article, we study the asymptotic behaviour of solutions of a first-order stochastic lattice dynamical system with an additive noise. We do not assume any Lipschitz condition on the nonlinear term, just a continuity assumption together with growth and dissipative conditions so that uniqueness of the Cauchy problem fails to be true. Using the theory of multi-valued random dynamical systems, we prove the existence of a random compact global attractor.
ATTRACTORS FOR A LATTICE DYNAMICAL SYSTEM GENERATED BY NON-NEWTONIAN FLUIDS MODELING SUSPENSIONS
In this paper we consider a lattice dynamical system generated by a parabolic equation modeling suspension flows. We prove the existence of a global compact connected attractor for this system and the upper semicontinuity of this attractor with respect to finite-dimensional approximations. Also, we obtain a sequence of approximating discrete dynamical systems by the implementation of the implicit Euler method, proving the existence and the upper semicontinuous convergence of their global attractors.
On a Retarded Nonlocal Ordinary Differential System with Discrete Diffusion Modeling Life Tables
In this paper, we consider a system of ordinary differential equations with non-local discrete diffusion and finite delay and with either a finite or an infinite number of equations. We prove several properties of solutions such as comparison, stability and symmetry. We create a numerical simulation showing that this model can be appropriate to model dynamical life tables in actuarial or demographic sciences. In this way, some indicators of goodness and smoothness are improved when comparing with classical techniques.
The Level of Mortality in Insured Populations
In the actuarial field, life tables are used in reserving and pricing processes. They are commonly built from aggregate data and incorporate margins as a prudent measure to ensure the insurance company’s viability. Solvency II requires insurance companies to calculate technical provisions using best-estimate assumptions for future experience (mortality, expenses, lapses, etc) to separate (i) the risk-free component from (ii) adverse deviation of claims. Nowadays, however, the methods used by insurance companies (in most countries, included Spain) do not guarantee that these components can be separated. Many companies build their own tables from general insured population life tables, assumi…
Introducing migratory flows in life table construction
The purpose of life tables is to describe the mortality behav iour of particular groups. The construction of general life tables is based on death statis tics and census figures of resident populations under the hypothesis of closed demographic sys tem. Among other assumptions, this hypothesis implicitly assumes that entries (immigrants) a nd exits (emigrants) of the population are usually not significant (being almost of the same magnitu de for each age compensating each other). This paper theoretically extends the classical sol ution to open demographic systems and studies the impact of this hypothesis in constructing a life table. In particular, using the data of residential variations m…
Attractors of stochastic lattice dynamical systems with a multiplicative noise and non-Lipschitz nonlinearities
AbstractIn this paper we study the asymptotic behavior of solutions of a first-order stochastic lattice dynamical system with a multiplicative noise.We do not assume any Lipschitz condition on the nonlinear term, just a continuity assumption together with growth and dissipative conditions, so that uniqueness of the Cauchy problem fails to be true.Using the theory of multi-valued random dynamical systems we prove the existence of a random compact global attractor.
Using Parametric Bootstrap to Introduce and Manage Uncertainty: Replicated Loaded Insurance Life Tables
Insurance companies develop loaded life tables to protect themselves against deviations, for example, in the number of expected deaths or in the (residual) expectation of life of their insured. In ...
On the connectedness of the attainability set for lattice dynamical systems
We prove the Kneser property (i.e. the connectedness and compactness of the attainability set at any time) for lattice dynamical systems in which we do not know whether the property of uniqueness of the Cauchy problem holds or not. Using this property, we can check that the global attractor of the multivalued semiflow generated by such system is connected.
Random resampling numerical simulations applied to a SEIR compartmental model
AbstractIn this paper, we apply resampling techniques to a modified compartmental SEIR model which takes into account the existence of undetected infected people in an epidemic. In particular, we implement numerical simulations for the evolution of the first wave of the COVID-19 pandemic in Spain in 2020. We show, by using suitable measures of goodness, that the point estimates obtained by the bootstrap samples improve the ones of the original data. For example, the relative error of detected currently infected people is equal to 0.061 for the initial estimates, while it is reduced to 0.0538 for the mean over all bootstrap estimated series.
Corporate board and default risk of financial firms
This paper analyses the impact of corporate board structure on default risk of European banking firms. We focus on four core aspects of boards that have been addressed in Directive 2013/36/ EU to strengthen the corporate governance of banks: the size of boards, their independence, the participation of female directors and CEO duality. We employ panel data analysis to study the 109 European listed banks between 2002 and 2019. Default risk is estimated by Merton’s (1974) distance to default. We take into account the presence of unobservable heterogeneity, simultaneity and dynamic endogeneity and estimate the model using the dynamic difference and dynamic system GMM methodologies. The results …
Higher education and the development of competencies for innovation in the workplace
PurposeThis paper aims to analyze the production function nexus between higher education practice and the development of innovation‐related competencies by university graduates in Spain. The research hypothesis is the presence of statistically significant relationships between the development of innovational competencies and the modes of teaching and learning used in higher education practice.Design/methodology/approachThe relationships are modeled through a set of stochastic frontier and variance component equations with the development of each competency as the dependent variable. The main explanatory variables capture the prevalence of diverse teaching/learning modes and the behavior of …
Assessing implicit hypotheses in life table construction
AbstractMortality figures are of capital importance for policy-making and public planning, as in forecasting financial provisions in public pension systems. General population life tables are constructed from aggregated statistics, an issue that usually entails adopting some (implicit) assumptions in their construction, such as the hypothesis of closed demographic system or the hypotheses of uniform distributions of death counts (and migration events) by age and calendar year. As microdata have become more abundant and reliable, these hypotheses could be assessed and more assumption-free estimators employed. Using a real database from Spain, we show that the above hypotheses are not appropr…
On the Kneser property for reaction–diffusion equations in some unbounded domains with an -valued non-autonomous forcing term
Abstract In this paper, we prove the Kneser property for a reaction–diffusion equation on an unbounded domain satisfying the Poincare inequality with an external force taking values in the space H − 1 . Using this property of solutions we check also the connectedness of the associated global pullback attractor. We study also similar properties for systems of reaction–diffusion equations in which the domain is the whole R N . Finally, the results are applied to a generalized logistic equation.
On the Kneser property for reaction–diffusion systems on unbounded domains
Abstract We prove the Kneser property (i.e. the connectedness and compactness of the attainability set at any time) for reaction–diffusion systems on unbounded domains in which we do not know whether the property of uniqueness of the Cauchy problem holds or not. Using this property we obtain that the global attractor of such systems is connected. Finally, these results are applied to the complex Ginzburg–Landau equation.