SO(3) vs. SU(2) Yang-Mills theory on the lattice: an investigation at non-zero temperature

The adjoint SU(2) lattice gauge theory in 3+1 dimensions with the Wilson plaquette action modified by a Z(2) monopole suppression term is reinvestigated with special emphasis on the existence of a finite-temperature phase transition decoupling from the well-known bulk transitions.Comment: 13 pages, 9 figures. Based on contributions to CONFINEMENT 2003 and Lattice2003(topology). To be published in Proceedings of CONFINEMENT 2003, Tokyo, Japa

SO(3) Yang-Mills theory on the lattice

We numerically investigate the phase structure of pure SO(3) LGT at zero and non-zero temperature in the presence of a Z2 blind monopole chemical potential. The physical meaning of the different phases, a possible symmetry breaking mechanism as well as the existence of an order parameter for the finite temperature phase transition are discussed.Comment: 3 pages, 2 figures LaTeX file. Uses espcrc2 style and amssymb package. Talk given at Lattice2002(nonzerot), Boston. Corrected version with one added referenc

MINISTAR: A Small Spacecraft for GEO Missions

This paper provides the information of the conceptual design of MINISTAR and presents the major features of this small spacecraft, able to support geostationary missions for satellite communications. MINISTAR is a sun pointing satellite, with despun antenna provided with momentum wheels to achieve gyroscopic stiffness along the pitch axis, maintained orthogonal to the geosynchronous orbit. Thrusters supply the attitude stabilization for yaw and roll axes and station keeping maneuvers. An unified propulsion system is adopted, with helium pressurized bipropellant. The system makes use of monomethyhl hydrazine as propellant and nitrogen tetroxide as oxidizer. Large autonomy is provided by the on-board system management. The communications\u27 payload power/mass ranges from 200 W/50 Kg to 600 W/100 Kg allowing payloads with volume of 0.13 m3 and a maximum antenna diameter of 1.8 m. MINISTAR can be launched as co-passenger by ARIANE or TITAN

Fixed twist dynamics of SO(3) gauge theory

We perform a throughout study of 3+1 dim. SO(3) LGT for any fixed-twist background. We concentrate in particular on the physically significant trivial and 1-twist sectors. Introducing a Z(2) monopole chemical potential the 1st order bulk transition is moved down in the strong coupling region and weakened to 2nd order in the 4-dim Ising model universality class. In this extended phase diagram we gain access to a confined phase in every fixed twist sector of the theory. The Pisa disorder operator is employed together with the Polyakov loop to study the confinement-deconfinement transition in each sector. Due to the specific properties of both operators, most results can be used to gain insight in the ergodic theory, where all twist sectors should be summed upon. An explicit mapping of each fixed twist theory to effective positive plaquette models with fixed twisted boundary conditions is applied to better establish their properties in the different phases.Comment: 20 pages, 11 Figures. Minor changes in text and figures, to appear in Eur.Phys.J.

A finite temperature investigation of dual superconductivity in the modified SO(3) lattice gauge theory

We study the SO(3) lattice gauge theory in 3+1 dimensions with the adjoint Wilson action modified by a $\mathbb{Z}_2$ monopole suppression term and by means of the Pisa disorder operator. We find evidence for a finite temperature deconfinement transition driven by the condensation of U(1) magnetic charges. A finite-size scaling test shows consistency with the critical exponents of the 3D Ising model.Comment: 14 pages, 4 figures. Layout changed, figures, text and references added. To appear on Physics Letters

DNA analysis as tool for identification of bacteria in archaeological waterlogged wood

Abstract In this work molecular techniques were applied in order to integrete the results obtained by Optical (OM) and Scanning Electron (SEM) Microscopy, to understanding and assessing the changes in the anatomical structure of archaeological waterlogged wood (Pinus sp.) induced by bacteria colonization. Observation of wooden thin sections revealed by OM showed the presence of black and dark -brown areas (must probably due to sulphur compounds) and mineral concretions. The SEM micrographs revealed a specific cell wall alteration attributable to bacterial activity and abundant pyrite framboids (as single structure or clustered). The presence of sulfur compounds in archaeological waterlogged wood, indicate both long-term burial in anoxic environment and colonization by sulfate-reducing bacteria. Molecular biology investigation was performed through ad hoc protocols by direct DNA extraction from wood samples and in vitro amplification of bacteria DNA target sequence (16S, ITS regions-r RNA). The results reveal and identify bacterial genus as Pseudomonas, Cellulomonas, Xanthomonas and Bacillus that, as reported in the related scientific literature, are the most common cellulosolytic and ligninolytic bacteria. Moreover were also revealed the presence of Marinobacter sp. and Desulforudis audaxviator, respectively iron- oxidizing and sulfate- reducing bacteria. The investigation protocol set up in this work can be applied to a range of wooden artifacts of archaeological findings for both identification of bacteria colonization shed some light on the degradation phenomena, indispensable for correct conservation and restoration strategies