Multiobjective Local Search Techniques for Evolutionary Polygonal Approximation

Proceedings of: 10th International Symposium on Distributed Computing and Artificial Intelligence . University of Salamanca (DCAI 2013). Salamanca, Spain, Spain, May 22-24, 2013.Polygonal approximation is based on the division of a closed curve into a set of segments. This problem has been traditionally approached as a single-objective optimization issue where the representation error was minimized according to a set of restrictions and parameters. When these approaches try to be subsumed into more recent multi-objective ones, a number of issues arise. Current work successfully adapts two of these traditional approaches and introduces them as initialization procedures for a MOEA approach to polygonal approximation, being the results, both for initial and final fronts, analyzed according to their statistical significance over a set of traditional curves from the domain.This work was supported in part by Projects MEyC TEC2012-37832-C02-01, MEyC TEC2011-28626-C02-02 and CAM CONTEXTS (S2009/TIC-1485).Publicad

First-principles study of (BiScO3){1-x}-(PbTiO3){x} piezoelectric alloys

We report a first-principles study of a class of (BiScO3)_{1-x}-(PbTiO3)_x (BS-PT) alloys recently proposed by Eitel et al. as promising materials for piezoelectric actuator applications. We show that (i) BS-PT displays very large structural distortions and polarizations at the morphotropic phase boundary (MPB) (we obtain a c/a of ~1.05-1.08 and P_tet of ~1.1 C/m^2); (ii) the ferroelectric and piezoelectric properties of BS-PT are dominated by the onset of hybridization between Bi/Pb-6p and O-2p orbitals, a mechanism that is enhanced upon substitution of Pb by Bi; and (iii) the piezoelectric responses of BS-PT and Pb(Zr_{1-x}Ti_x)O3 (PZT) at the MPB are comparable, at least as far as the computed values of the piezoelectric coefficient d_15 are concerned. While our results are generally consistent with experiment, they also suggest that certain intrinsic properties of BS-PT may be even better than has been indicated by experiments to date. We also discuss results for PZT that demonstrate the prominent role played by Pb displacements in its piezoelectric properties.Comment: 6 pages, with 3 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/ji_bi/index.htm

Measures on Banach Manifolds and Supersymmetric Quantum Field Theory

We show how to construct measures on Banach manifolds associated to supersymmetric quantum field theories. These measures are mathematically well-defined objects inspired by the formal path integrals appearing in the physics literature on quantum field theory. We give three concrete examples of our construction. The first example is a family $\mu_P^{s,t}$ of measures on a space of functions on the two-torus, parametrized by a polynomial $P$ (the Wess-Zumino-Landau-Ginzburg model). The second is a family \mu_\cG^{s,t} of measures on a space \cG of maps from $\P^1$ to a Lie group (the Wess-Zumino-Novikov-Witten model). Finally we study a family $\mu_{M,G}^{s,t}$ of measures on the product of a space of connection s on the trivial principal bundle with structure group $G$ on a three-dimensional manifold $M$ with a space of \fg-valued three-forms on $M.$ We show that these measures are positive, and that the measures \mu_\cG^{s,t} are Borel probability measures. As an application we show that formulas arising from expectations in the measures \mu_\cG^{s,1} reproduce formulas discovered by Frenkel and Zhu in the theory of vertex operator algebras. We conjecture that a similar computation for the measures $\mu_{M,SU(2)}^{s,t},$ where $M$ is a homology three-sphere, will yield the Casson invariant of $M.$Comment: Minor correction

Global Sourcing of IT Services and Information Security: Prudence before Playing

This paper calls for awareness of the risks in global sourcing of IT and IT-enabled services. It calls for appropriate assessment and mitigation of these risks. The authors identify ways in which global sourcing (often called offshoring) increases information security exposures and strategies for managing such risks

First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

We show that a simple first-principles correction based on the difference between the singlet-triplet CO excitation energy values obtained by DFT and high-level quantum chemistry methods yields accurate CO adsorption properties on a variety of metal surfaces. We demonstrate a linear relationship between the CO adsorption energy and the CO singlet-triplet splitting, similar to the linear dependence of CO adsorption energy on the energy of the CO 2$\pi$* orbital found recently {[Kresse {\em et al.}, Physical Review B {\bf 68}, 073401 (2003)]}. Converged DFT calculations underestimate the CO singlet-triplet excitation energy $\Delta E_{\rm S-T}$, whereas coupled-cluster and CI calculations reproduce the experimental $\Delta E_{\rm S-T}$. The dependence of $E_{\rm chem}$ on $\Delta E_{\rm S-T}$ is used to extrapolate $E_{\rm chem}$ for the top, bridge and hollow sites for the (100) and (111) surfaces of Pt, Rh, Pd and Cu to the values that correspond to the coupled-cluster and CI $\Delta E_{\rm S-T}$ value. The correction reproduces experimental adsorption site preference for all cases and obtains $E_{\rm chem}$ in excellent agreement with experimental results.Comment: Table sent as table1.eps. 3 figure

Lattice instabilities of PbZrO3/PbTiO3 [1:1] superlattices from first principles

Ab initio phonon calculations for the nonpolar reference structures of the (001), (110), and (111) PbZrO_3/PbTiO_3 [1:1] superlattices are presented. The unstable polar modes in the tetragonal (001) and (110) structures are confined in either the Ti- or the Zr-centered layers and display two-mode behavior, while in the cubic (111) case one-mode behavior is observed. Instabilities with pure oxygen character are observed in all three structures. The implications for the ferroelectric behavior and related properties are discussed.Comment: 12 pages, 2 figures, 7 tables, submitted to PR

A Geometric Formulation of Quantum Stress Fields

We present a derivation of the stress field for an interacting quantum system within the framework of local density functional theory. The formulation is geometric in nature and exploits the relationship between the strain tensor field and Riemannian metric tensor field. Within this formulation, we demonstrate that the stress field is unique up to a single ambiguous parameter. The ambiguity is due to the non-unique dependence of the kinetic energy on the metric tensor. To illustrate this formalism, we compute the pressure field for two phases of solid molecular hydrogen. Furthermore, we demonstrate that qualitative results obtained by interpreting the hydrogen pressure field are not influenced by the presence of the kinetic ambiguity.Comment: 22 pages, 2 figures. Submitted to Physical Review B. This paper supersedes cond-mat/000627

IL-2 limits IL-12 enhanced lymphocyte proliferation during \u3ci\u3eLeishmania amazonensis\u3c/i\u3e infection

C3H mice infected with Leishmania amazonensis develop persistent, localized lesions with high parasite loads. During infection, memory/effector CD44hiCD4+ T cells proliferate and produce IL-2, but do not polarize to a known effector phenotype. Previous studies have demonstrated IL-12 is insufficient to skew these antigen-responsive T cells to a functional Th1 response. To determine the mechanism of this IL-12 unresponsiveness, we used an in vitro assay of repeated antigen activation. Memory/effector CD44hiCD4+ T cells did not increase proliferation in response to either IL-2 or IL-12, although these cytokines upregulated CD25 expression. Neutralization of IL-2 enhanced CD4+ T cell proliferation in response to IL-12. This cross-regulation of IL-12 responsiveness by IL-2 was confirmed in vivo by treatment with anti-IL-2 antibodies and IL-12 during antigen challenge of previously infected mice. These results suggest that during chronic infection with L. amazonensis, IL-2 plays a dominant, immunosuppressive role independent of identifiable conventional Treg cells

MicroRNAs in bovine milk exosomes are bioavailable in humans but do not elicit a robust pro-inflammatory cytokine response

Background: Bovine milk exosomes are studied for their roles as bioactive food compounds and as vehicles for drug delivery. Both lines of investigation converge on immune function, e.g., immune regulation by absorption of microRNAs encapsulated in milk exosomes across species boundaries, and the possibility of exosomes and their cargos triggering an immune response if used in drug delivery. This study assessed the bioavailability of immune-related microRNAs from bovine milk and changes in plasma cytokine concentrations after milk consumption in humans, and the secretion of cytokines by human peripheral blood mononuclear cells (PBMCs) cultured with milk exosomes transfected with immune-relevant microRNAs. Results: Human plasma samples were collected before and at timed intervals after a milk meal and analyzed for concentrations of six immune-relevant microRNAs and nine cytokines. The peak plasma concentrations of miR-15b-5p, miR- 21-5p, miR-106b-5p, and miR-223-3p were 60 ± 9.80% to 162 ± 31.80% higher after milk consumption (Ct values 23 ± 1.2 to 26 ± 1.1 cycles) compared to baseline values (P \u3c 0.05). Plasma concentrations of TNF-alpha were not significantly different before versus after milk consumption; eight other cytokines were below detection limit. PBMCs were collected before and six hours after milk consumption and cultured with or without concanavalin A (ConA). TNF-alpha, IL-1β, IL-6 and IL-10 were detectable in culture media, but concentrations did not depend on milk consumption prior to PBMC isolation (P \u3e 0.05). When PBMC cultures from fasted subjects were supplemented with milk exosomes that had been transfected with immune-relevant microRNAs, the concentrations of IL-1β, IL-6, IL-10 and TNF-alpha were 29 ± 12% to 220 ± 33% higher than controls cultured with non-transfected exosomes (P \u3c 0.05), but cytokine concentrations were not different compared with control exosomes transfected with scrambled microRNA (P \u3e 0.05). Conclusions: MicroRNAs in bovine milk exosomes are bioavailable. Milk exosomes do not elicit an increase of plasma cytokines following oral administration