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

Evidence for a Very Large-Scale Fractal Structure in the Universe from Cobe Measurements

In this work, we analyse the temperature fluctuations of the cosmic microwave background radiation observed by COBE and show that the distribution can be fitted by a fractal distribution with a fractal dimension $D= 1.43 \pm 0.07$. This value is in close agreement with the fractal dimension obtained by Coleman and Pietronero (1992) and Luo and Schramm (1992) from galaxy-galaxy and cluster-cluster correlations up to $\sim 100 h^{-1} Mpc$. The fact that the observed temperature fluctuations correspond to scales much larger than $100 h^{-1} Mpc$ and are signatures of the primordial density fluctuations at the recombination layer suggests that the structure of the matter at the early universe was already fractal and thus non-homogeneous on those scales. This result may have important consequences for the theoretical framework that describes the universe.Comment: 11 pages, postscript file, 2 figures available upon request. To appear in ApJ Letter

Efeito da aplicação do efluente da agroindústria do dendê sobre características químicas de um latossolo amarelo álico, textura média.

bitstream/item/48925/1/Boletim-PD-11-AMAZ-ORIENTAL.pd

Experimental Investigation of the Dip Effect in Rectangular Channel

Two different data sets (LDA, propeller) were used to observe the occurrence of the dip effectin rectangular open channel flow for aspect ratios 1.5  B/H  12. The measured andcalculated velocity distributions are compared and three different situations are detected,depending on the magnitude of the aspect ratio (B/H). When B/H  5 no dip effect wasobserved and the measured distributions along the cross section were in very good agreementalong whole depth with the distributions as calculated by the entropy equation. When B/H < 2the calculated distributions diverge from the measured ones for all vertical lines along thecross section due to the effects of free surface and sidewall. The dip effect for 2≤ B/H <5 overthe cross section is found only for verticals near the sidewall, where equation applicability isrestricted. Herein, empirical correction for the entropy velocity distribution is proposed toaccount for dip effect. For validation propeller measurements were used. Relative velocityerrors by adjusted equation were found to be only 32% of that by the original entropyequation for the near-surface (z/H  0.75) region

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)

Avanços no conhecimento da diversidade de mosca-das-frutas (Diptera: Tephritidae) no município de Belém, PA.

A preocupação com a qualidade sanitária dos produtos na fruticultura tem sido fator primordial, já que muitos frutos são consumidos ?in natura?. Esta pesquisa objetivou avaliar os avanços no conhecimento da diversidade de moscas-das-frutas (Diptera: Tephritidae) e seus hospedeiros no município de Belém, Pará. Entre outubro de 2007 e junho de 2008 foram realizadas coletas de frutos em diferentes locais da base física da Embrapa Amazônia Oriental. Frutos coletados foram quantificados, pesados e processados em bandejas plásticas contendo areia esterilizada para obtenção de pupários e adultos de moscas-das-frutas e seus parasitóides. Das 27 amostras coletadas, 62,96% apresentaram-se infestadas por mosca-das-frutas e somente cinco espécies vegetais não foram infestadas. O maior índice de infestação (28,13 pupários/kg de frutos) foi constatado no hospedeiro abiu (Pouteria caimito). A espécie de moscas-das-frutas Anastrepha obliqua Macquart é a que possui maior número de hospedeiros no município de Belém, PA.PIBIC-2011