Ropivacaine 0.2% may be an alternative to 0.5% lidocaine for intravenous regional anesthesia in the outpatient surgical setting. Longer-lasting analgesia in the immediate postoperative period may be due to a more profound and prolonged tissue binding effect of ropivacaine.

Puccinia coronata avenae, Puccinia gram inis tritici, L ipoxygenase, Elicitor, H ypersensitive R eac tionThe hypersensitive reaction in incom patible wheat-rust interactions is characterized by an increase in lipoxygenase activity detectable as early as 28 h after penetration o f the pathogen. In contrast, lipoxygenase activity in the com patible interaction did not increase until the onset o f sporulation.Lipoxygenase activity also increased follow ing treatm ent o f wheat leaves with an elicitor frac tion from germ tubes o f Puccinia gram inis tritici. In trod u ctionH ost cell necrosis is recognized as one of the most prom inent defense mechanisms against biotrophic parasites such as the rust fungi. Light and electron microscopic studies have dem onstrated that in some incom patible interactions rapid localized host cell death accom panies this type of response to the inva sion of an avirulent pathogen [1][2][3][4].A lterations in m em brane structure resulting in leakage of electrolytes and serious disorder to cellu lar control mechanisms would be expected to occur concom itantly with cell death [see review 5]. M em brane disorganization may result from lipoxygenasecatalyzed peroxidation of membrane lipids; this in cludes the peroxidation of the ds,ds-l,4 -p en tad ien e systems commonly found in unsaturated fatty acids to the corresponding conjugated hydroperoxides. We therefore investigated the activity of lipoxygen ase in susceptible and resistant wheat cultivars inocu lated with Puccinia graminis tritici or, alternatively, with a nonpathogenic organism, Puccini coronata avenae. In addition, results are presented concerning the effect of an elicitor fraction isolated from germ tubes of w heat stem rust uredospores on the activity of lipoxygenase. A bbreviation s: Pgt, Puccinia gram inis tritici; Pea, Puccinia coronata avenae. Reprint requests to Prof. Dr. H. J. Grambow. Verlag der Zeitschrift für Naturforschung, D -7400 Tübingen 0 3 4 1 -0 3 8 2 /8 6 /0 5 0 0 -0 5 5 9 $ 01.30/0 M aterials and M eth o d s H ost and pathogenW heat plants were grown in a growth cham ber at 20 °C, 50-60% relative humidity, 16 h light regime and 15 klux. Primary leaves of 7 day-old plants were inoculated with uredospores or treated with elicitor. The following wheat cultivars were used throughout the experiments; cv. M arquis, which is susceptible to Puccinia gram inis tritici (Pgt), race 32, and which exhibits hypersensitivity to the non-pathogen Puc cinia coronata avenae (Pea); the corresponding, nearly isogenic line of cv. M arquis which carries the Sr5 gene for resistance against Pgt; cv. 417/65 which is highly resistant to Pgt, race 32.U redospores of Pgt, race 32, were collected from infected leaves of wheat cv. Little Club, and stored either at 4 °C for a few days or frozen in liquid nitro gen at -192 °C where they m aintained their infectivity over long periods. U redospores of Pea were col lected from oat cv. Pc40 and stored under the same conditions as Pgt.Plants were infected by spraying them with a sus pension of ur...

It is well known that many nonlinear phenomena such as bifurcations and chaotic behavior occur in DC-DC converters mainly due to the switching action among all the different topologies of the circuit. Such behavior has been described with detail numerically, and also mathematical reasoning has been provided. In this paper we focuss on the experimental side of a DC-DC Buck converter controlled with two different strategies: classical Pulse Width Modulation (PWM) with a ramp and a more recently described Zero Average Dynamics (ZAD). We show some nonsmooth events and we explain with detail the experimental setups. In one of them, we use a FPGA card to obtain on-line results. In the other we use Virtual InstrumenPartially funded by SICONOS. tation to generate an experimental two-dimensional bifurcation diagram, which will be compared to the numerical data. After the data acquisition of the system state variables some elaborated post-processing must be made. This is done through LabView. Although the main application of these results is centered in avoiding non-periodic or high-amplitude periodic behavior, they can also be applied to reducing the generated electromagnetic interference and to the information transmission.

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