Analytical Results for Abelian Projection

Analytic methods for Abelian projection are developed, and a number of results related to string tension measurements are obtained. It is proven that even without gauge fixing, Abelian projection yields string tensions of the underlying non-Abelian theory. Strong arguments are given for similar results in the case where gauge fixing is employed. The subgroup used for projection need only contain the center of the gauge group, and need not be Abelian. While gauge fixing is shown to be in principle unnecessary for the success of Abelian projection, it is computationally advantageous for the same reasons that improved operators, e.g., the use of fat links, are advantageous in Wilson loop measurements.Comment: LATTICE98(confine), 3 pages, 1 eps figur

Relationships between body symmetry during weight-bearing and functional reach among chronic hemiparetic patients

Contextualização: O controle postural está freqüentemente prejudicado nas condições de hemiparesias. Quando na posição em pé, sujeitos hemiparéticos oscilam mais do que sujeitos sem hemicorpo afetado, adotando posturas assimétricas com maior descarga de peso na perna não afetada. Objetivo: Analisar o alcance funcional e a dependência por dispositivo de apoio em hemiparéticos crônicos, verificando correlações entre deslocamentos de alcance funcional e valores de simetria de descarga de peso durante a posição em pé. Métodos: Quatorze hemiparéticos classificados em dependentes ou independentes de dispositivo de apoio foram incluídos nos procedimentos experimentais para registro de deslocamento de alcance funcional e valores de simetria. Resultados: Nenhuma diferença significativa foi obtida entre os dependentes e os independentes de dispositivo de apoio para todas as variáveis. Porém, quando a descarga de peso ocorreu no lado não afetado, os mais altos deslocamentos foram significativamente correlacionados com os hemiparéticos mais assimétricos. Conclusão: A simetria não favorece o alcance funcional nem a independência de dispositivo de apoio em hemiparéticos.Background: Postural control is often impaired in hemiparetic patients. During upright stance, hemiparetic subjects sway more than subjects with an unaffected hemibody, and they assume asymmetrical postures to place less weight on the affected side. Objective: To analyze functional reach and dependence on support devices among people with chronic hemiparesis and to investigate the relationships between displacements of functional reach and weight-bearing symmetry during upright stance. Methods: Fourteen participants with hemiparesis, classifed as dependent on support devices or independent from them, were included in experimental procedures to record functional reach displacements and symmetry values. Results: No signifcant differences were found between the dependent and independent participants for any variable. However, when weight-bearing occurred on the unaffected side, the greatest displacements were signifcantly correlated with the most asymmetrical hemiparetic participants. Conclusion: Symmetry did not contribute to functional reach or independence from support devices among participants with hemiparesis

Soft Covariant Gauges on the Lattice

We present an exploratory study of a one-parameter family of covariant, non-perturbative lattice gauge-fixing conditions, that can be implemented through a simple Monte Carlo algorithm. We demonstrate that at the numerical level the procedure is feasible, and as a first application we examine the gauge dependence of the gluon propagator.Comment: 11 pages, Latex, epsf.sty included + 5 PostScript picture

Theory of Abelian Projection

Analytic methods for Abelian projection are developed. A number of results are obtained related to string tension measurements. It is proven that even without gauge fixing, abelian projection yields string tensions of the underlying non-Abelian theory. Strong arguments are given for similar results in the case where gauge fixing is employed. The methods used emphasize that the projected theory is derived from the underlying non-Abelian theory rather than vice versa. In general, the choice of subgroup used for projection is not very important, and need not be Abelian. While gauge fixing is shown to be in principle unnecessary for the success of Abelian projection, it is computationally advantageous for the same reasons that improved operators, e.g., the use of fat links, are advantageous in Wilson loop measurements. Two other issues, Casimir scaling and the conflict between projection and critical universality, are also discussed.Comment: Minor corrections, new section added, 14 pages, 3 figures, RevTe

Nonperturbative Gauge Fixing and Perturbation Theory

We compare the gauge-fixing approach proposed by Jona-Lasinio and Parrinello, and by Zwanziger (JPLZ) with the standard Fadeev-Popov procedure, and demonstrate perturbative equality of gauge-invariant quantities, up to irrelevant terms induced by the cutoff. We also show how a set of local, renormalizable Feynman rules can be constructed for the JPLZ procedure.Comment: 9 pages, latex, version to appear in Phys. Rev.

Problems in Lattice Gauge Fixing

We review many topics and results about numeric gauge fixing in lattice QCD.Comment: 47 pages, 16 eps figures. Review article sent to IJMP

Activity and Process Stability of Purified Green Pepper (Capsicum annuum) Pectin Methylesterase

Pectin methylesterase (PME) from green bell peppers (Capsicum annuum) was extracted and purified by affinity chromatography on a CNBr-Sepharose-PMEI column. A single protein peak with pectin methylesterase activity was observed. For the pepper PME, a biochemical characterization in terms of molar mass (MM), isoelectric points (pI), and kinetic parameters for activity and thermostability was performed. The optimum pH for PME activity at 22 °C was 7.5, and its optimum temperature at neutral pH was between 52.5 and 55.0 °C. The purified pepper PME required the presence of 0.13 M NaCl for optimum activity. Isothermal inactivation of purified pepper PME in 20 mM Tris buffer (pH 7.5) could be described by a fractional conversion model for lower temperatures (55?57 °C) and a biphasic model for higher temperatures (58?70 °C). The enzyme showed a stable behavior toward high-pressure/temperature treatments. Keywords: Capsicum annuum; pepper; pectin methylesterase; purification; characterization; thermal and high-pressure stabilit

Dual Superconductor Scenario of Confinement: A Systematic Study of Gribov Copy Effects

We perform a study of the effects from maximal abelian gauge Gribov copies in the context of the dual superconductor scenario of confinement, on the basis of a novel approach for estimation of systematic uncertainties from incomplete gauge fixing. We present numerical results, in SU(2) lattice gauge theory, using the overrelaxed simulated annealing gauge fixing algorithm. We find abelian and non-abelian string tensions to differ significantly, their ratio being 0.92(4) at BETA = 2.5115. An approximate factorization of the abelian potential into monopole and photon contributions has been confirmed, the former giving rise to the abelian string tension.Comment: 35 pages uucompressed LaTeX with 10 encapsuled postscript figure

Low Sugar Is Not Always Good: Impact of Specific O-Glycan Defects on Tip Growth in Arabidopsis

Mutants of the O-glycosylation pathway of extensins as well as molecular dynamics simulations uncover the effects of the O-glycosylation machinery on root hair tip growth

O Acadêmico João Ubaldo Ribeiro, a Administração, a Ciência e a Política

Não posso iniciar meus comentários sobre o texto sem lembrar que João Ubaldo foi meu colega, entre outros brasileiros, no curso de Mestrado em Administração Pública da University of Southern California (USC), localizada em Los Angeles, California, nos idos de 1963-65. Um bom colega. Acho que nenhum de nós suspeitava que João Ubaldo seria um escritor famoso. Sabíamos ser ele um jornalista, porque assim se declarava, e que estava cursando o mestrado para ser professor de uma universidade brasileira, como todos nós. Mas havia um diferencial, pelo menos. Enquanto todos nós, ou quase todos, estávamos ainda engatinhando no domínio da língua inglesa, João Ubaldo já a dominava perfeitamente. Era capaz de imitar o sotaque de várias regiões dos Estados Unidos ou da Inglaterra, herança de uma educação atenta e rigorosa. Isso nos espantava e nos provocava admiração. O que hoje não é de surpreender, pois que seus livros Sargento Getúlio e Viva o Povo Brasileiro foram publicados com versão em inglês do próprio João Ubaldo