11-interval PFG pulse sequence for improved measurement of fast velocities of fluids with high diffusivity in systems with short T2*

Magnetic resonance (MR) was used to measure SF6 gas velocities in beds filled with particles of 1.1 mm and 0.5 mm in diameter. Four pulse sequences were tested: a traditional spin echo pulse sequence, the 9-interval and 13-interval pulse sequence of Cotts et al. (1989) and a newly developed 11-interval pulse sequence. All pulse sequences measured gas velocity accurately in the region above the particles at the highest velocities that could be achieved (up to 0.1 m s-1). The spin echo pulse sequence was unable to measure gas velocity accurately in the bed of particles, due to effects of background gradients, diffusivity and acceleration in flow around particles. The 9- and 13-interval pulse sequence measured gas velocity accurately at low flow rates through the particles (expected velocity < 0.06 m s-1), but could not measure velocity accurately at higher flow rates. The newly developed 11-interval pulse sequence was more accurate than the 9- and 13-interval pulse sequences at higher flow rates, but for velocities in excess of 0.1 m s-1 the measured velocity was lower than the expected velocity. The increased accuracy arose from the smaller echo time that the new pulse sequence enabled, reducing selective attenuation of signal from faster moving nuclei

Isolamento e identificação da microbiota periodontal de cães da raça Pastor Alemão Isolate and identify of periodontal microbiota of German Shepherd dogs

A microbiota indígena gengival de cães não está totalmente descrita, sendo sua identificação uma etapa importante no estabelecimento da etiopatogenia e terapia da doença periodontal. O objetivo deste trabalho foi isolar e identificar a microbiota periodontal de cães da raça Pastor Alemão, considerando sítios saudáveis e com doença periodontal. Foram utilizados 29 cães, com idade variando de três a seis anos, sendo analisados espécimes clínicos de sítios periodontais saudáveis de 12 cães e sítios com periodontite de outros 17. Foram isoladas 672 amostras microbianas, com predomínio dos gêneros Pasteurella, Staphylococcus, Porphyromonas e Fusobacterium. A microbiota dos sítios saudáveis equiparou-se à dos sítios doentes, tratando-se de uma microbiota indígena. A microbiota dos sítios doentes apresentou-se aumentada em relação a dos sítios saudáveis, indicando mudança do ambiente do sítio periodontal.<br>The indigenous gingival microbiota of dogs is not totally described, although such identification is an important step to establish the etiopathogenesis and adequate therapy for the periodontal disease. The aims of this study were to isolate and identify the periodontal microbiota of German Shepherd dogs from healthy and with periodontal desease sites. Twenty nine German Shepherd dogs from three to six years of age were used in this study. Clinical specimens were analysed from healthy periodontal sites of 12 dogs and sites presenting gingivitis of 17 dogs. A total amount of 672 microbial samples, were isolated where the predominant genera were Pasteurella spp., Staphylococcus spp., Porphyromonas spp. and Fusobacterium spp. The microbiological population of the affected sites was similar to the healthy sites, consisting on an indigenous microbiota. The microbiota on the affecteded sites was higher in number than on the healthy sites, showing change in the environment of the periodontal sites