9,632 research outputs found

    On the formation of ephippia in some Cladocera (Crustacea) [Translation from: Zoologicheskie Zhurnal 61, 1425-1427, 1982]

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    The determination of relative connections between families and genera of Cladocera, necessary for the construction of their natural systems, must be based on various criteria, among them on the structure of the ephippia. Of particular interest is the study of the process of formation and structure of the ephippium in Macrothricidae, different representatives of which differ significantly among themselves according to this criterion. In this article are presented the results of an investigation of the features of formation of the ephippium in seven species of Macrothricidae and in the moinid Moina weismanni Ishikawa (Moinidae)

    Rotational ordering and symmetry breaking in the triangular antiferromagnetic Heisenberg lattice

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    Finite system calculations suggest a rotational ordering in the ground state of the triangular antiferromagnetic Heisenberg lattice. This rotational ordering may result in a rotational symmetry breaking for quantum-spin systems, which does not show a net sublattice magnetization

    The consideration of surrogate model accuracy in single-objective electromagnetic design optimization

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    The computational cost of evaluating the objective function in electromagnetic optimal design problems necessitates the use of cost-effective techniques. This paper describes how one popular technique, surrogate modelling, has been used in the single-objective optimization of electromagnetic devices. Three different types of surrogate model are considered, namely polynomial approximation, artificial neural networks and kriging. The importance of considering surrogate model accuracy is emphasised, and techniques used to improve accuracy for each type of model are discussed. Developments in this area outside the field of electromagnetic design optimization are also mentioned. It is concluded that surrogate model accuracy is an important factor which should be considered during an optimization search, and that developments have been made elsewhere in this area which are yet to be implemented in electromagnetic design optimization

    Scalarizing cost-effective multiobjective optimization algorithms made possible with kriging

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    The use of kriging in cost-effective single-objective optimization is well established, and a wide variety of different criteria now exist for selecting design vectors to evaluate in the search for the global minimum. Additionly, a large number of methods exist for transforming a multi-objective optimization problem to a single-objective problem. With these two facts in mind, this paper discusses the range of kriging assisted algorithms which are possible (and which remain to be explored) for cost-effective multi-objective optimization

    Rapid reversion from monomer to dimer regenerates the ultraviolet-B photoreceptor UV RESISTANCE LOCUS8 in intact arabidopsis plants

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    Arabidopsis (Arabidopsis thaliana) UV RESISTANCE LOCUS8 (UVR8) is a photoreceptor that specifically mediates photomorphogenic responses to ultraviolet (UV)-B in plants. UV-B photoreception induces the conversion of the UVR8 dimer into a monomer that interacts with the CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) protein to regulate gene expression. However, it is not known how the dimeric photoreceptor is regenerated in plants. Here, we show, by using inhibitors of protein synthesis and degradation via the proteasome, that the UVR8 dimer is not regenerated by rapid de novo synthesis following destruction of the monomer. Rather, regeneration occurs by reversion from the monomer to the dimer. However, regeneration of dimeric UVR8 in darkness following UV-B exposure occurs much more rapidly in vivo than in vitro with illuminated plant extracts or purified UVR8, indicating that rapid regeneration requires intact cells. Rapid dimer regeneration in vivo requires protein synthesis, the presence of a carboxyl-terminal 27-amino acid region of UVR8, and the presence of COP1, which is known to interact with the carboxyl-terminal region. However, none of these factors can account fully for the difference in regeneration kinetics in vivo and in vitro, indicating that additional proteins or processes are involved in UVR8 dimer regeneration in vivo

    Balancing Exploration and Exploitation using Kriging Surrogate Models in Electromagnetic Design Optimization

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    The balance between exploration and exploitation is an important issue when attempting to find the global minimum of an objective function. This paper describes how this balance may be carefully controlled when using Kriging surrogate models to approximate the objective function

    A thermodynamic approximation of the ground state of antiferromagnetic heisenberg spin−1/2 lattices

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    The exact ground state of finite Heisenberg spin−1/2 lattices isstudied. The coefficients of the so-called Ising configurations contributing to the ground state are approximated by Boltzmann-like expressions. These expressions contain a parameter that may be related to an inverse temperature

    Applied genetics of tilapias

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    This paper reviews the successes and failures of genetic experiments on tilapias and points to various characteristics of tilapias, which require improvement for increased yields.Tilapia culture, Genetics, Aquaculture techniques Tilapia, Sarotherodon
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