Máquinas para agricultores familiares: ideias, inovações e criações apresentadas na 3ª Mostra de Máquinas e inventos.

bitstream/item/130184/1/EMBRAPA-CLIMA-TEMPERADO-LIVRO-MAQUINAS-PARA-AGRICULTORES-FAMILIARES.pdfPelotas, Embrapa Clima Temperado

X-Ray Scattering at FeCo(001) Surfaces and the Crossover between Ordinary and Normal Transitions

In a recent experiment by Krimmel et al. [PRL 78, 3880 (1997)], the critical behavior of FeCo near a (001) surface was studied by x-ray scattering. Here the experimental data are reanalyzed, taking into account recent theoretical results on order-parameter profiles in the crossover regime between ordinary and normal transitions. Excellent agreement between theoretical expectations and the experimental results is found.Comment: 9 pages, Latex, 1 PostScript figure, to be published in Phys.Rev.

Tecnologias para os sistemas de produção de desenvolvimento sustentável da agricultura familiar: projeto RS Rural.

Princípios orientadores da pesquisa participativa; Atividades de pesquisa e desenvolvimento; Pesquisa em sistema de produção; Produção de base ecológica na Região Arrozeira Sul do RS; Biodiversidade; Validação, transferência e sistematização de tecnologias; Rede de referência; Atividades de intercâmbio e extensão.bitstream/item/107691/1/CPACT-TECN.-PARA-OS-SIST.-DE-PROD.-E-DESENVOL.-SUSTEN.-DA-AGRIC.-FAMI.-05.pd

Absolute Frequency Measurements of the Hg^+ and Ca Optical Clock Transitions with a Femtosecond Laser

The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg^+ and Ca optical standards with respect to the SI second as realized at NIST. We find the transition frequencies to be f_Hg=1 064 721 609 899 143(10) Hz and f_Ca=455 986 240 494 158(26) Hz, respectively. In addition to the unprecedented precision demonstrated here, this work is the precursor to all-optical atomic clocks based on the Hg^+ and Ca standards. Furthermore, when combined with previous measurements, we find no time variations of these atomic frequencies within the uncertainties of |(df_Ca/dt)/f_Ca| < 8 x 10^{-14} yr^{-1}, and |(df_Hg/dt)/f_Hg|< 30 x 10^{-14} yr^{-1}.Comment: 6 pages, including 4 figures. RevTex 4. Submitted to Phys. Rev. Let

Sub-dekahertz ultraviolet spectroscopy of 199Hg+

Using a laser that is frequency-locked to a Fabry-Perot etalon of high finesse and stability, we probe the 5d10 6s 2S_1/2 (F=0) - 5d9 6s 2D_5/2 (F=2) Delta-m_F = 0 electric-quadrupole transition of a single laser-cooled 199Hg+ ion stored in a cryogenic radio-frequency ion trap. We observe Fourier-transform limited linewidths as narrow as 6.7 Hz at 282 nm (1.06 X 10^15 Hz), yielding a line Q = 1.6 X 10^14. We perform a preliminary measurement of the 5d9 6s2 2D_5/2 electric-quadrupole shift due to interaction with the static fields of the trap, and discuss the implications for future trapped-ion optical frequency standards.Comment: 4 pages, 4 figures, submitted for publicatio

Cluster Model of Decagonal Tilings

A relaxed version of Gummelt's covering rules for the aperiodic decagon is considered, which produces certain random-tiling-type structures. These structures are precisely characterized, along with their relationships to various other random tiling ensembles. The relaxed covering rule has a natural realization in terms of a vertex cluster in the Penrose pentagon tiling. Using Monte Carlo simulations, it is shown that the structures obtained by maximizing the density of this cluster are the same as those produced by the corresponding covering rules. The entropy density of the covering ensemble is determined using the entropic sampling algorithm. If the model is extended by an additional coupling between neighboring clusters, perfectly ordered structures are obtained, like those produced by Gummelt's perfect covering rules.Comment: 10 pages, 20 figures, RevTeX; minor changes; to be published in Phys. Rev.

INTOXICAÇÃO AGUDA PELA SAMAMBAIA (Pteridium aquilinum, L. Kuhn), EM BOVINOS DA RAÇA ABERDEEN ANGUS

Os autores descrevem a ocorrência de um surto de intoxicação aguda pela samambaia (Pteridium aquilinum, L. Kuhn), em bovinos da raça Aberdeen angus, criados numa propriedade rural localizada no município de Ortigueira, estado do Paraná. Um total de 14 animais vieram a óbito e a ocorrência do surto reacende a necessidade de encontrar soluções, mesmo que paliativas, para a prevenção de novos episódios. Segundo os autores, a superlotação de animais nos piquetes, tornaram as pastagens cultivadas muito baixas, favorecendo a procura pela samambaia, que mantinha-se mais viçosa e atraente ao consumo, o que possibilitou uma ingestão de grande quantidade em curto espaço de tempo. Acute intoxication by bracken fern (Pteridium aquilinum, L. Kuhn) In Aberdeen angus breed Abstract The present paper gives an account of a herd intoxication caused by the ingestion of bracken fern (Pteridium aquilinum,L. Kuhn) that took place in a farm at the region of Ortigueira, State of Paraná. Fourteen Aberdeen Angus bovines died of acute intoxication caused by the ingestion of large amounts of this toxic plant. Overpopulated and low nutrient quality pastured areas induce the large ingestion of bracken fern. Due to these reasons there is an urgent need for adequate solutions aiming to prevent the occurrence of such episodes