Theoretical study of the mechanisms of fatigue in photomultipliers, phase 2 Final report

Fatigue testing of photomultipliers with gallium phosphide dynode

Distributed Services with Foreseen and Unforeseen Tasks: The Mobile Re-allocation Problem

In this paper we deal with a common problem found in the operations of security and preventive/corrective maintenance services: that of routing a number of mobile resources to serve foreseen and unforeseen tasks during a shift. We define the (Mobile Re-Allocation Problem) MRAP as the problem of devising a routing strategy to maximize the expected weighted number of tasks served on time. For obtaining a solution to the MRAP, we propose to solve successively a multi-objective optimization problem called the stochastic Team Orienteering Problem with Multiple Time Windows (s-TOP-MTW) so as to consider information about known tasks and the arrival process of new unforeseen tasks. Solving successively the s-TOP-MTW we find that considering information about the arrival process of new unforeseen tasks may aid in maximizing the expected proportion of tasks accomplished on time.location;reliability;routing;distributed services

Distributed Services with Foreseen and Unforeseen Tasks: The Mobile Re-allocation Problem

In this paper we deal with a common problem found in the operations of security and preventive/corrective maintenance services: that of routing a number of mobile resources to serve foreseen and unforeseen tasks during a shift. We define the (Mobile Re-Allocation Problem) MRAP as the problem of devising a routing strategy to maximize the expected weighted number of tasks served on time. For obtaining a solution to the MRAP, we propose to solve successively a multi-objective optimization problem called the stochastic Team Orienteering Problem with Multiple Time Windows (s-TOP-MTW) so as to consider information about known tasks and the arrival process of new unforeseen tasks. Solving successively the s-TOP-MTW we find that considering information about the arrival process of new unforeseen tasks may aid in maximizing the expected proportion of tasks accomplished on time

Testing fixed points in the 2D O(3) non-linear sigma model

Using high statistic numerical results we investigate the properties of the O(3) non-linear 2D sigma-model. Our main concern is the detection of an hypothetical Kosterlitz-Thouless-like (KT) phase transition which would contradict the asymptotic freedom scenario. Our results do not support such a KT-like phase transition.Comment: Latex, 7 pgs, 4 eps-figures. Added more analysis on the KT-transition. 4-loop beta function contains corrections from D.-S.Shin (hep-lat/9810025). In a note-added we comment on the consequences of these corrections on our previous reference [16

Critical properties of Ising model on Sierpinski fractals. A finite size scaling analysis approach

The present paper focuses on the order-disorder transition of an Ising model on a self-similar lattice. We present a detailed numerical study, based on the Monte Carlo method in conjunction with the finite size scaling method, of the critical properties of the Ising model on some two dimensional deterministic fractal lattices with different Hausdorff dimensions. Those with finite ramification order do not display ordered phases at any finite temperature, whereas the lattices with infinite connectivity show genuine critical behavior. In particular we considered two Sierpinski carpets constructed using different generators and characterized by Hausdorff dimensions d_H=log 8/log 3 = 1.8927.. and d_H=log 12/log 4 = 1.7924.., respectively. The data show in a clear way the existence of an order-disorder transition at finite temperature in both Sierpinski carpets. By performing several Monte Carlo simulations at different temperatures and on lattices of increasing size in conjunction with a finite size scaling analysis, we were able to determine numerically the critical exponents in each case and to provide an estimate of their errors. Finally we considered the hyperscaling relation and found indications that it holds, if one assumes that the relevant dimension in this case is the Hausdorff dimension of the lattice.Comment: 21 pages, 7 figures; a new section has been added with results for a second fractal; there are other minor change

Caracterização da resposta à toxina Cry1Ac em populações de Noctuídeos pragas da soja no Brasil.

A soja geneticamente modificada resistente a insetos e tolerante ao glifosato (MON 87701 × MON 89788), contendo o gene Cry1Ac, tem como principais alvos as lagartas desfolhadoras Pseudoplusia includens (Walker) e Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae). Em algumas regiões, Rachiplusia nu (Guenée) também pode ser uma importante praga, como no Rio Grande do Sul e sul do Paraná. Portanto, estudos sobre a variabilidade espacial e temporal de respostas à toxina Cry1Ac de populações destas espécies são essenciais para a realização de monitoramento da suscetibilidade, contribuindo para o futuro manejo da resistência. Populações de P. includens (n= 14) e A. gemmatalis (n= 7) foram coletadas nas safras 2008/09 a 2010/11, e uma população de R. nu foi coletada em Bento Gonçalves, RS. As populações foram provenientes de regiões representativas da cultura de soja no Brasil (BA, MT, GO, SP, PR e RS). Bioensaios realizados com a toxina purificada indicaram variações na suscetibilidade de 2,5 vezes nas populações de P. includens e três vezes nas populações de A. gemmatalis. As CL50 determinadas para P. includens variaram de 0,81 a 2,01 μg.mL-1 de dieta, enquanto que para A. gemmatalis as variações foram de 0,03 a 0,09 μg.mL-1 para as populações de campo. O valor da CL50 para R. nu foi de 0,70 ?g.mL-1 de dieta. Para a população de A. gemmatalis adaptada às condições de laboratório, a CL50 foi de 0,21 μg.mL-1 de dieta, maior que os valores observados nos bioensaios com as populações de campo. Indicando menor suscetibilidade, devido provavelmente a maior adaptação à dieta ou às condições de laboratório, após 199 gerações. As espécies ordenadas de menor a maior tolerância foram A. gemmatalis, R. nu e P. includens. Os resultados obtidos permitiram o inicio dos estudos de validação para monitoramento futuro das possíveis alterações de suscetibilidade à toxina Cry1Ac. 0,70 ?g.mL-

QCD chiral Lagrangian on the lattice, strong coupling expansion and Ward identities with Wilson fermions

We discuss a general strategy to compute the coefficients of the QCD chiral Lagrangian using lattice QCD with Wilson fermions. This procedure requires the introduction of a lattice chiral Lagrangian as an intermediate step in the calculation. The QCD chiral Lagrangian is then obtained by expanding the lattice effective theory in increasing powers of the lattice spacing and the external momenta. In order to investigate the consequences of the chiral symmetry breaking induced by the Wilson term, we study the lattice chiral Lagrangian at the leading order of the strong coupling and large $N$ expansion. We show that the effects of the Wilson term can be conveniently taken into account, in the lattice effective theory, by a suitable renormalization procedure. In particular, we show that, at the leading order of the strong coupling and large N expansion, the chiral symmetry is exactly recovered on the lattice provided that the bare quark mass and the lattice operators are properly renormalized.Comment: 45 pages, no figures. Latex fil

The Coulomb law in the pure gauge U(1) theory on a lattice

We study the heavy charge potential in the Coulomb phase of pure gauge compact U(1) theory on the lattice. We calculate the static potential $V_W(T,{\vec R})$ from Wilson loops on a $16^3 \times 32$ lattice and compare with the predictions of lattice perturbation theory. We investigate finite size effects and, in particular, the importance of non-Coulomb contributions to the potential. We also comment on the existence of a maximal coupling in the Coulomb phase of pure gauge U(1) theory.Comment: 14 pages. LaTeX file and 3 postscript figure

Lattice QCD at the physical point: Simulation and analysis details

We give details of our precise determination of the light quark masses m_{ud}=(m_u+m_d)/2 and m_s in 2+1 flavor QCD, with simulated pion masses down to 120 MeV, at five lattice spacings, and in large volumes. The details concern the action and algorithm employed, the HMC force with HEX smeared clover fermions, the choice of the scale setting procedure and of the input masses. After an overview of the simulation parameters, extensive checks of algorithmic stability, autocorrelation and (practical) ergodicity are reported. To corroborate the good scaling properties of our action, explicit tests of the scaling of hadron masses in N_f=3 QCD are carried out. Details of how we control finite volume effects through dedicated finite volume scaling runs are reported. To check consistency with SU(2) Chiral Perturbation Theory the behavior of M_\pi^2/m_{ud} and F_\pi as a function of m_{ud} is investigated. Details of how we use the RI/MOM procedure with a separate continuum limit of the running of the scalar density R_S(\mu,\mu') are given. This procedure is shown to reproduce the known value of r_0m_s in quenched QCD. Input from dispersion theory is used to split our value of m_{ud} into separate values of m_u and m_d. Finally, our procedure to quantify both systematic and statistical uncertainties is discussed.Comment: 45 page