Improvement of the hot QCD pressure by the minimal sensitivity criterion

The principles of minimal sensitivity (PMS) criterion is applied to the perturbative free energy density, or pressure, of hot QCD, which include the $\sim g_s^6 \ln g_s$ and part of the $\sim g_s^6$ terms. Applications are made separately to the short- and long-distance parts of the pressure. Comparison with the lattice results, at low temperatures, shows that the resultant `` optimal'' approximants are substantially improved when compared to the $\bar{MS}$ results. In particular, for the realistic case of three quark flavors, the `` optimal'' approximants are comparable with the lattice results.Comment: 14 pages, 9 figures, LaTe

O mutualismo como forma de gestão de risco na agricultura.

A agricultura é, notadamente, uma atividade que apresenta grau elevado de risco. Fenômenos climáticos extremos, por exemplo, podem afetar, de forma negativa, a produtividade e a rentabilidade do setor. Para protegerem-se desse risco os produtores utilizam mecanismos que buscam mitigá-lo, dos quais o mutualismo é uma das formas mais antigas. Este artigo enfoca, de maneira analítica, as principais iniciativas dos produtores de criar, por meio de suas cooperativas, sociedades mútuas que os assegurem contra eventos aleatórios adversos

Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory

The group theory framework developed by Fukutome for a systematic analysis of the various broken symmetry types of Hartree-Fock solutions exhibiting spin structures is here extended to the general many body context using spinor-Green function formalism for describing magnetic systems. Consequences of this theory are discussed for examining the magnetism of itinerant electrons in nanometric systems of current interest as well as bulk systems where a vector spin-density form is required, by specializing our work to spin-density-functional formalism. We also formulate the linear response theory for such a system and compare and contrast them with the recent results obtained for localized electron systems. The various phenomenological treatments of itinerant magnetic systems are here unified in this group-theoretical description.Comment: 17 page

Search for magnetic monopoles using proportional counters filled with helium gas

Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level