Recent results on Charm Physics from Fermilab

New high statistics, high resolution fixed target experiments producing $10^5$ - $10^6$ fully reconstructed charm particles are allowing a detailed study of the charm sector. Recent results on charm quark production from Fermilab fixed target experiments E791, SELEX and FOCUS are presented.Comment: 27 pages, corrected some typographical errors. To appear Proc. VII Mexican Workshop of Particles and Field, Merida Yuc. M\'ex., Nov. 199

Asymmetry studies in Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ production

We present a study on hyperon/anti-hyperon production asymmetries in the framework of the recombination model. The production asymmetries for Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ are studied as a function of x_F. Predictions of the model are compared to preliminary data on hyperon/anti-hyperon production asymmetries in 500 GeV/c pi- p interactions from the Fermilab E791 experiment. The model predicts a growing asymmetry with the number of valence quarks shared by the target and the produced hyperons in the x_F < 0 region. In the positive x_F region, the model predicts constant asymmetries for Lambda 0/Lambda 0-bar and Omega-/Omega+ production and a growing asymmetry with x_F for Xi-/Xi+. We found a qualitatively good agreement between the model predictions and data, showing that recombination is a competitive mechanism in the hadronization process.Comment: One reference correcte

On the intrinsic charm and the recombination mechanisms in charm hadron production

We study $\Lambda_c^\pm$ production in $pN$ and $\pi^-N$ interactions. Recent experimental data from the SELEX and E791 Collaborations at FNAL provide important information on the production mechanism of charm hadrons. In particular, the production of the $\Lambda_c$ baryon provides a good test of the intrinsic charm and the recombination mechanisms, which have been proposed to explain the so called leading particle effects.Comment: 11 pages, two figures (postscript), late

The Charm of the Proton and the Λc+\Lambda _c^{+} Production

We propose a two component model for charmed baryon production in $pp$ collisions consisting of the conventional parton fusion mechanism and fragmentation plus quarks recombination in which a $ud$ valence diquark from the proton recombines with a $c$-sea quark to produce a $\Lambda_c^+$. Our two-component model is compared with the intrinsic charm two-component model and experimental data.Comment: 6 pages, LaTex, 2 figures included, aipproc.sty included. Talk presented at Simposio Latino Americano de Fisica de Altas Energias, Merida, Mexico, November 199

Comparação entre tração motorizada e animal.

Avaliação do desempenhop técnico e econômico da tração animal motomecanizada na propriedade agrícola.bitstream/item/137381/1/ID-31043.pdfApostila do Curso de Atualização Técnica para Engenheiro para Engenheiros Agrônomos do Banco do Brasil, Petrolina

Implementos e métodos de preparo do solo agrícola.

bitstream/item/136345/1/ID-31075.pdfApostila do Curso de Capacitação sobre Manejo e Melhoramento do Solo com ênfase em Métodos de Preparo Efetivo do Solo, 1997, Ibadan, Nigéria

Barrador de sulcos a tracao animal: construcao e uso.

O trabalho teve por objetivo desenvolver o implemento barrador de sulcos a tração animal, sua construção e uso. Trata-se de uma tecnologia capaz de reduzir o escoamento superficial da água de chuva ou de irrigação, promovendo, assim, uma maior infiltração e favorecendo um melhor aproveitamento do sistema solo-água- planta