Feynman versus Bakamjian-Thomas in Light Front Dynamics

We compare the Bakamjian-Thomas (BT) formulation of relativistic few-body systems with light front field theories that maintain closer contact with Feynman diagrams. We find that Feynman diagrams distinguish Melosh rotations and other kinematical quantities belonging to various composite subsystem frames that correspond to different loop integrals. The BT formalism knows only the rest frame of the whole composite system, where everything is evaluated.Comment: 5 page

Iron Compounds in Brazilian Pre-Columbian Pigments Identified by \u3csup\u3e57\u3c/sup\u3eFe Mossbauer Spectroscopy and X-Ray Powder Diffraction

Mossbauer spectroscopy and X-ray powder diffraction have been used to identify iron compounds in pre-Columbian pigments, probably used for art decorating, collected from the oldest archaeological site of Early Man presently known in American at Sao Raimundo Nonato, in Northeastern Brazil. The iron compounds were identified as being alpha-Fe203 (haematite) with full Morin transition supressed and small particles of alpha-FeOOH (goethite)

Características físicas de cereal matinal elaborado por extrusão enriquecido de frutooligossacarídeo.

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Physical properties of single-crystalline fibers of the colossal-magnetoresistance manganite La0.7Ca0.3MnO3

We have grown high-quality single crystals of the colossal-magnetoresistance (CMR) material La0.7Ca0.3MnO3 by using the laser heated pedestal growth (LHPG) method. Samples were grown as fibers of different diameters, and with lengths of the order of centimeters. Their composition and structure were verified through X-ray diffraction, scanning electron microcopy with EDX (Energy Dispersive X-ray Analysis) and by Rietveld analysis. The quality of the crystalline fibers was confirmed by Laue and EBSD (Electron Backscatter Diffraction) patterns. Rocking curves performed along the fiber axis revealed a half-height width of 0.073 degrees. The CMR behavior was confirmed by electrical resistivity and magnetization measurements as a function of temperature.Comment: 11 pages (including 3 figures); to appear in Appl. Phys. Let

Índice de infestação de frutos de pitangueira por Anastrepha obliqua (Macquart) (Diptera: Tephritidae) no Município de Belém, Pará.

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New country, Brazilian states and host records of the eucalypt shoot psyllid Blastopsylla occidentalis.

O psilídeo das ponteiras do eucalipto, Blastopsylla occidentalis Taylor, 1985 (Hemiptera: Psylloidea) é relatado aqui pela primeira vez para o Burundi, Indonésia (Sumatra), Nicarágua, Filipinas e Iêmen. O registro desta para o Paraguai mostrou ser um erro. Novos registros são dados para os estados brasileiros Bahia, Ceará, Piauí e Rio Grande do Sul. Eucalyptus viminalis é listado pela primeira vez como hospedeiro de B. occidentalis.Nota científica