1,721,216 research outputs found
A phenomenological operator description of interactions between populations with applications to migration
No full textWe adopt an operatorial method based on the so–called creation, annihilation and
number operators in the description of different systems in which two populations
interact and move in a two–dimensional region. In particular, we discuss diffusion
processes modeled by a quadratic hamiltonian. This general procedure will
be adopted, in particular, in the description of migration phenomena. With respect
to our previous analogous results, we use here fermionic operators since they
automatically implement an upper bound for the population densities
Quantum Modeling of Love Affairs
No full textWe adopt the so-called number representation, originally used in quantum me- chanics and recently considered in the description of stock markets, in the analysis of the dynamics of love relation. We present a simple model, involv- ing two actors (Alice and Bob), and we consider either a linear model or a nonlinear model
An Operator--like Description of Love Affairs
No full textWe adopt the so--called \emph{occupation number representation}, originally used in
quantum mechanics and recently
considered in the description of stock markets, in the analysis of
the dynamics of love relations. We start with a simple model,
involving two actors (Alice and Bob): in the linear case we obtain periodic dynamics,
whereas in the nonlinear regime either periodic or quasiperiodic solutions are found.
Then we extend the model to a love triangle involving Alice, Bob and a third actress,
Carla. Interesting features appear, and in particular we find analytical conditions for the linear model of love triangle to have periodic or quasiperiodic solutions. Numerical solutions are exhibited in the nonlinear case
Dynamics of closed ecosystems described by operators
No full textWe adopt the so-called occupation number representation, originally used in quantum mechanics and recently adopted in the description of several classical systems, in the analysis of the dynamics of some models of closed ecosystems. In particular, we discuss two linear models, for which the solution can be found analytically, and a nonlinear system, for which we produce numerical results. We also discuss how a dissipative effect could be effectively implemented in the model
Cinnamomum Oliveri F. M. Bailey Leaf Solvent Extractions Inhibit the Growth of a Panel of Pathogenic Bacteria
No full textIntroduction: Cinnamomum oliveri F. M. Bailey is a rain forest tree native to Australia. Decoctions, infusions and essential oils produced from the leaves were used traditionally to treat a variety of bacterial diseases. Despite this, C. oliveri leaf extractions have not been rigorously examined for antibacterial properties against many pathogens. Methods: The antimicrobial activity of C. oliveri leaf extractions was investigated by disc diffusion and growth time course assays against a panel of pathogenic bacteria. The growth inhibitory activity was quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: C. oliveri leaf solvent extractions inhibited the growth of a wide range of bacterial species. Growth of both gram positive and gram negative bacteria was inhibited by the C. oliveri leaf extracts to approximately the same extent. The methanolic extracts were generally most potent growth inhibitors. The methanolic, aqueous and ethyl acetate C. oliveri leaf extracts were particularly potent inhibitors of P. mirabilis growth, with MIC values as low as 127 μg/mL (methanolic extract). A. coli, K. pneumoniae and B. cereus were also particularly susceptible to the methanolic, aqueous and ethyl acetate extracts, with MIC values generally substantially <1000 μg/ mL. The antibacterial activity of the methanolic C. oliveri leaf extract was further investigated by growth time course assays which showed significant growth inhibition in cultures of E. coli, K. pneumoniae and P. mirabilis within 1 h of exposure. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for internal use as well as for topical uses. Conclusions: The lack of toxicity of the C. oliveri leaf extracts and their growth inhibitory bioactivity against a panel of pathogenic bacteria partially validate the traditional usage of these species to treat bacterial diseases and indicate their potential in the development of antiseptic agents.Full Tex
A particle-mesh numerical method for advection-reaction-diffusion equations with applications to plankton modeling.
No full textWe present a new method for the numerical solution of advection-reaction-diffusion equations. The method is lagrangian for the advection-reaction part, and uses an auxiliary eulerian grid for the diffusive operator. We discuss the application of the method to the modelling of planktonic populations
Population Dynamics in Large Domains
No full textThis chapter uses our operator-based approach adopting truncated bosonic operators to analyze the population dynamics in a confined 2D region with a complex topology. The Hamiltonian operator that encompasses the interactions and mechanisms among the populations, is built (also) in terms of the density and of the transport operators. The time evolution is determined by the Schrödinger equation, and the population densities are computed from the normalized expected values of the density operators. Our approach proves to be efficient for large domains, addressing the computational challenges often encountered in Hamiltonian approaches using fermionic ladder operators
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