872 research outputs found

    On Multiobjective Evolution Model

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    Self-Organized Criticality (SOC) phenomena could have a significant effect on the dynamics of ecosystems. The Bak-Sneppen (BS) model is a simple and robust model of biological evolution that exhibits punctuated equilibrium behavior. Here we will introduce random version of BS model. Also we generalize the single objective BS model to a multiobjective one.Comment: 6 pages, 5 figure

    A comparative study of two key algorithms in multiple objective linear programming

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    Multiple objective linear programming problems are solved with a variety of algorithms. While these algorithms vary in philosophy and outlook, most of them fall into two broad categories: those that are decision space-based and those that are objective space-based. This paper reports the outcome of a computational investigation of two key representative algorithms, one of each category, namely the parametric simplex algorithm which is a prominent representative of the former and the primal variant of Bensons Outer-approximation algorithm which is a prominent representative of the latter. The paper includes a procedure to compute the most preferred nondominated point which is an important feature in the implementation of these algorithms and their comparison. Computational and comparative results on problem instances ranging from small to medium and large are provided

    An international proficiency test to detect, identify and quantify ricin in complex matrices

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    While natural intoxications with seeds of Ricinus communis have long been known, the toxic protein ricin contained in the seeds is of major concern due to its history of criminal, terrorist and military use. In order to harmonize detection capabilities in expert laboratories an international proficiency test was organized that aimed at identifying good analytical practices (qualitative measurements) and determining a consensus concentration on a highly pure ricin reference material (quantitative measurements). Sample materials included highly pure ricin as well as the related R. communis agglutinin spiked into buffer, milk and meat extract; additionally, an organic fertilizer naturally contaminated with R. communis shred was investigated in the proficiency test. The qualitative results showed that either a suitable combination of immunological, MS-based and functional approaches or sophisticated MS-based approaches alone successfully allowed to detect and identify ricin in all samples. In terms of quantification, it was possible to determine a consensus concentration for the highly pure ricin reference material. The results provide a basis for further steps in quality assurance and improve biopreparedness in expert laboratories worldwide.JRC.D.2-Standards for Innovation and sustainable Developmen

    Analysis of the Lepton Mixing Matrix in the Two Higgs Doublet Model

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    In the theoretical framework of Two Higgs Doublet Model (2HDM) plus three right-handed neutrinos we consider a universal treatment for the mass matrices, aside from that the active neutrinos acquire their small mass through the type-I seesaw mechanism. Then, as long as a matrix with four-zero texture is used to represent the right-handed neutrinos and Yukawa matrices, we obtain a unified treatment where all fermion mass matrices have four-zero texture. We obtain analytical and explicit expressions for the lepton flavour mixing matrix PMNS in terms of fermion masses and parameters associated with the 2HDM-III. Further, we compare these expressions of the PMNS matrix with the most up to date values of masses and mixing in the lepton sector, via a likelihood test. We find that the analytical expressions that we derived reproduce remarkably well the most recent experimental data of neutrino oscillations

    Managing the Knowledge Creation Process of Large-Scale Evaluation Campaigns

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    Περιέχει το πλήρες κείμενοThis paper discusses the evolution of large-scale evaluation campaigns and the corresponding evaluation infrastructures needed to carry them out. We present the next challenges for these initiatives and show how digital library systems can play a relevant role in supporting the research conducted in these fora by acting as virtual research environments

    Standstill Electric Charge Generates Magnetostatic Field Under Born-Infeld Electrodynamics

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    The Abelian Born-Infeld classical non-linear electrodynamic has been used to investigate the electric and magnetostatic fields generated by a point-like electrical charge at rest in an inertial frame. The results show a rich internal structure for the charge. Analytical solutions have also been found. Such findings have been interpreted in terms of vacuum polarization and magnetic-like charges produced by the very high strengths of the electric field considered. Apparently non-linearity is to be accounted for the emergence of an anomalous magnetostatic field suggesting a possible connection to that created by a magnetic dipole composed of two mognetic charges with opposite signals. Consistently in situations where the Born-Infeld field strength parameter is free to become infinite, Maxwell`s regime takes over, the magnetic sector vanishes and the electric field assumes a Coulomb behavior with no trace of a magnetic component. The connection to other monopole solutions, like Dirac`s, t' Hooft`s or Poliakov`s types, are also discussed. Finally some speculative remarks are presented in an attempt to explain such fields.Comment: 11 pages, 3 figures. In this version is update a permanent address of the author L.P.G. De Assis and information on submission publication. Submetted to International Journal of Theoretical Physic
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