Analysis of false waves in numerical sea simulations

[EN] It is common practice to consider the random sea waves as a succession of discrete waves characterized by individual amplitudes and periods. The zero-up-crossing criterion for discretizing waves, as well as other criteria proposed by different authors, has been found to isolate some discrete waves that do not correspond to physical waves. These false waves alter the wave statistics of random sea waves. A new orbital criterion is proposed to avoid this problem. The orbital criterion has been shown to be consistent and robust with respect to the zero-up-crossing criterion. Furthermore, the new criterion produces a distribution of wave heights in better agreement with the Rayleigh distribution. The mean period of the discrete waves corresponding to the orbital criterion is proved to be T01, while the mean period of the zero-up-crossing waves is T02. A formula relating the Longuet-Higgins spectral bandwidth nu with the relative number of false waves is given.Gimenez Valentin, MH.; Sánchez Carratalá, CR.; Medina, JR. (1994). Analysis of false waves in numerical sea simulations. Ocean Engineering. 21(8):751-764. doi:10.1016/0029-8018(94)90050-7S75176421

Light quenched hadron spectrum and decay constants on different lattices

In this paper we study O(2000) (quenched) lattice configurations from the APE collaboration, for different lattice volumes and for 6.0 less than or equal to beta less than or equal to 6.4 using both the Wilson and the SW-Clover fermion actions, We determine the light hadronic spectrum and meson decay constants and study the mesonic dispersion relation. We extract the hadronic variable J and the strange quark mass in the continuum at the next-to-leading order obtaining m(s)()(mu = 2 GeV) = 122 +/- 20 MeV. A study is made of their dependence on lattice spacing, We implement a newly developed technique to extract the inverse lattice spacing using data at the simulated values of the quark mass (i.e. at masses around the strange quark mass)

QCD moment sum rules for Coulomb systems: the charm and bottom quark masses

In this work the charm and bottom quark masses are determined from QCD moment sum rules for the charmonium and upsilon systems. To illustrate the special character of these sum rules when applied to Coulomb systems we first set up and study the behaviour of the sum rules in quantum mechanics. In our analysis we include both the results from nonrelativistic QCD and perturbation theory at next-next-to-leading order. The moments are evaluated at different values of q^2 which correspond to different relative influence among the theoretical contributions. In the numerical analysis we obtain the masses by choosing central values for all input parameters. The error is estimated from a variation of these parameters. First, the analysis is performed in the pole mass scheme. Second, we employ the potential-subtracted mass in intermediate steps of the calculation to then infer the quark masses in the MS-scheme. Our final results for the pole- and MS-masses are: M_c = 1.75 \pm 0.15 GeV, m_c(m_c) = 1.19 \pm 0.11 GeV, M_b = 4.98 \pm 0.125 GeV and m_b(m_b) = 4.24 \pm 0.10 GeV.Comment: 55 pages, 12 figures. References added, discussions extended. To appear in Phys. Rev.

Interclass GPCR heteromerization affects localization and trafficking

Membrane trafficking processes regulate G protein-coupled receptor (GPCR) activity. Although class A GPCRs are capable of activating G proteins in a monomeric form, they can also potentially assemble into functional GPCR heteromers. Here, we showed that the class A serotonin 5-HT receptors (5-HTRs) affected the localization and trafficking of class C metabotropic glutamate receptor 2 (mGluR2) through a mechanism that required their assembly as heteromers in mammalian cells. In the absence of agonists, 5-HTR was primarily localized within intracellular compartments, and coexpression of 5-HTR with mGluR2 increased the intracellular distribution of the otherwise plasma membrane-localized mGluR2. Agonists for either 5-HTR or mGluR2 differentially affected trafficking through Rab5-positive endosomes in cells expressing each component of the 5-HTR-mGluR2 hetero-complex alone, or together. In addition, overnight pharmacological 5-HTR blockade with clozapine, but not with M100907, decreased mGluR2 density through a mechanism that involved heteromerization between 5-HTR and mGluR2. Using TAT-tagged peptides and chimeric constructs that are unable to form the interclass 5-HTR-mGluR2 complex, we demonstrated that heteromerization was necessary for the 5-HTR-dependent effects on mGluR2 subcellular distribution. The expression of 5-HTR also augmented intracellular localization of mGluR2 in mouse frontal cortex pyramidal neurons. Together, our data suggest that GPCR heteromerization may itself represent a mechanism of receptor trafficking and sorting

Continuidade espacial da condutividade hidráulica saturada do solo na bacia hidrográfica do Alto Rio Grande, MG

A distribuição espacial da condutividade hidráulica saturada (k0) é essencial para estudos relacionados a erosão do solo e escoamento superficial. Este trabalho objetivou estudar a continuidade espacial do atributo hidrológico do solo k o na Bacia Hidrográfica do Alto Rio Grande, MG, e realizar seu mapeamento por meio de técnicas geoestatísticas, utilizando dados sem e com transformação logarítmica. Os modelos de semivariograma esférico e exponencial foram ajustados ao semivariograma experimental pelo método dos Mínimos Quadrados Ordinários (MQO) e Mínimos Quadrados Ponderados (MQP). Técnicas de validação cruzada e preditiva foram aplicadas para a escolha do melhor modelo. Os resultados indicaram que, ao se trabalhar com o logaritmo dos dados de k o, houve redução de pontos discrepantes e de anisotropia, entretanto os valores mais elevados de grau de dependência espacial foram observados nos dados sem transformação. O ajuste do modelo esférico, por meio do método MQO, foi o que produziu melhor desempenho na modelagem da continuidade espacial de k0. Os mapas gerados a partir dos dados sem e com transformação logarítmica não apresentaram o mesmo comportamento na distribuição espacial dos valores, e o mapa dos dados na forma transformada teve o melhor detalhamento da distribuição espacial