Coordination and Governance: The case of Cooperatives versus IOFs

Agribusiness,

An immune system based genetic algorithm using permutation-based dualism for dynamic traveling salesman problems

Copyright @ Springer-Verlag Berlin Heidelberg 2009.In recent years, optimization in dynamic environments has attracted a growing interest from the genetic algorithm community due to the importance and practicability in real world applications. This paper proposes a new genetic algorithm, based on the inspiration from biological immune systems, to address dynamic traveling salesman problems. Within the proposed algorithm, a permutation-based dualism is introduced in the course of clone process to promote the population diversity. In addition, a memory-based vaccination scheme is presented to further improve its tracking ability in dynamic environments. The experimental results show that the proposed diversification and memory enhancement methods can greatly improve the adaptability of genetic algorithms for dynamic traveling salesman problems.This work was supported by the Key Program of National Natural Science Foundation (NNSF) of China under Grant No. 70431003 and Grant No. 70671020, the Science Fund for Creative Research Group of NNSF of China under GrantNo. 60521003, the National Science and Technology Support Plan of China under Grant No. 2006BAH02A09 and the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant No. EP/E060722/1

Constant curvature solutions of Grassmannian sigma models: (1) Holomorphic solutions

We present a general formula for the Gaussian curvature of curved holomorphic 2-spheres in Grassmannian manifolds G(m, n). We then show how to construct such solutions with constant curvature. We also make some relevant conjectures for the admissible constant curvatures in G(m, n) and give some explicit expressions, in particular, for G(2, 4) and G(2, 5).Comment: 14 page

A simple derivation of level spacing of quasinormal frequencies for a black hole with a deficit solid angle and quintessence-like matter

In this paper, we investigate analytically the level space of the imaginary part of quasinormal frequencies for a black hole with a deficit solid angle and quintessence-like matter by the Padmanabhan's method \cite{Padmanabhan}. Padmanabhan presented a method to study analytically the imaginary part of quasinormal frequencies for a class of spherically symmetric spacetimes including Schwarzschild-de Sitter black holes which has an evenly spaced structure. The results show that the level space of scalar and gravitational quasinormal frequencies for this kind of black holes only depend on the surface gravity of black-hole horizon in the range of -1 < w < -1/3, respectively . We also extend the range of $w$ to $w \leq -1$, the results of which are similar to that in -1 < w < -1/3 case. Particularly, a black hole with a deficit solid angle in accelerating universe will be a Schwarzschild-de Sitter black hole, fixing $w = -1$ and $\epsilon^2 = 0$. And a black hole with a deficit solid angle in the accelerating universe will be a Schwarzschild black hole,when $\rho_0 = 0$ and $\epsilon^2 = 0$. In this paper, $w$ is the parameter of state equation, $\epsilon^2$ is a parameter relating to a deficit solid angle and $\rho_0$ is the density of static spherically symmetrical quintessence-like matter at $r = 1$.Comment: 6 pages, Accepted for publication in Astrophysics & Space Scienc

Surface structure and solidification morphology of aluminum nanoclusters

Classical molecular dynamics simulation with embedded atom method potential had been performed to investigate the surface structure and solidification morphology of aluminum nanoclusters Aln (n = 256, 604, 1220 and 2048). It is found that Al cluster surfaces are comprised of (111) and (001) crystal planes. (110) crystal plane is not found on Al cluster surfaces in our simulation. On the surfaces of smaller Al clusters (n = 256 and 604), (111) crystal planes are dominant. On larger Al clusters (n = 1220 and 2048), (111) planes are still dominant but (001) planes can not be neglected. Atomic density on cluster (111)/(001) surface is smaller/larger than the corresponding value on bulk surface. Computational analysis on total surface area and surface energies indicates that the total surface energy of an ideal Al nanocluster has the minimum value when (001) planes occupy 25% of the total surface area. We predict that a melted Al cluster will be a truncated octahedron after equilibrium solidification.Comment: 22 pages, 6 figures, 34 reference

Supersymmetric Electroweak Corrections to Charged Higgs Boson Production in Association with a Top Quark at Hadron Colliders

We calculate the $O(\alpha_{ew}m_{t(b)}^{2}/m_{W}^{2})$ and $O(\alpha_{ew} m_{t(b)}^4/m_W^4)$ supersymmetric electroweak corrections to the cross section for the charged Higgs boson production in association with a top quark at the Tevatron and the LHC. These corrections arise from the quantum effects which are induced by potentially large Yukawa couplings from the Higgs sector and the chargino-top(bottom)-sbottom(stop) couplings, neutralino-top(bottom)-stop(sbottom) couplings and charged Higgs-stop-sbottom couplings. They can decrease or increase the cross section depending on $\tan\beta$ but are not very sensitive to the mass of the charged Higgs boson for high $\tan\beta$. At low $\tan\beta(=2)$ the corrections decrease the total cross sections significantly, which exceed -12% for $m_{H^{\pm}}$ below $300GeV$ at both the Tevatron and the LHC, but for $m_{H^{\pm}}>300GeV$ the corrections can become very small at the LHC. For high $\tan\beta(=10,30)$ these corrections can decrease or increase the total cross sections, and the magnitude of the corrections are at most a few percent at both the Tevatron and the LHC.Comment: 28 pages including 4 eps figure

First Report of Alternaria Black Spot Disease Caused by Alternaria alternata on the Invasive Weed Solanum rostratum in Xinjiang, China

Solanum rostratum is a noxious weed, native to Mexico and the USA, which has invaded Liaoning, Jilin, Hebei, Inner Mongolia, Shanxi, Xinjiang and Beijing, China (Eminniya et al., 2013). In August 2015, foliar symptoms of yellowish to black spots were observed on plants of S. rostratum nearby an agricultural plantation in Changji, Xinjiang. The following year, about 17% of the 206 plants surveyed on about 0.2 ha of deserted farmland were infected from July-September (at 19-35°C under 29-97% RH)