Agrobacterium tumefaciens-mediated transformation revealed an alkaline phytoceramidase that is required in pathogenicity of Colletotrichum kahawae to Coffea arabica

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A high genomic variability is found among Hemileia vastatrix pathotypes

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First steps on the resistance profiling of Kawisari coffee hybrid through cytological and gene expression analyses

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Comparative characterization of resistance proteins in Coffea species

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Hysteretic Damping as an Energy Parameter in Gigacycle Fatigue

The mechanical behaviour of materials subjected to dynamic loading is now a classical subject but is still a big challenge. The fatigue limit of the materials, defined as the maximum dynamic load amplitude level for which no fatigue failures occur, has been set for a number of load cycles up to 10E7. Extending this limit with the traditional hardware is a much more difficult technical task due to the length of time needed for the completion of tests, but there is a real industrial concern about this subject due to the growing need to extend the lifecycle of some structures beyond such limits. Therefore, the study of fatigue is being extended to more than 10E7 cycles, typically 10E9 and more, in a new area of studies known as gigacycle fatigue. It is within this framework that the study presented in this paper fits. The approach here presented is based on the fact that the fatigue problem can be understood in terms of the energy available for irreversible process triggering. This energy will be involved in micro-structural irreversible changes in the material before being dissipated as thermal energy. The energy needed to trigger such changes must come from the dynamic loading. In fact, the balance between the energy supplied to and returned by the material is positive and the hysteretic damping factor represents the inelastic fraction of energy balance for each cycle.Final Accepted Versio

Influence of the Wave Form on the Material Response Delay

To model damping effects in structural dynamics, the literature provides a wide range of alternatives. The different models claim different advantages and fields of use where they are useful but, in the end, the compliance of the model with the experimental results, within a given tolerance, is the ultimate criterion for assessing its quality. In the present paper, the behaviour of a simple steel specimen is studied, taking as a focus the time response of the material. Since the harmonic response is well established, the authors propose to submit the specimen to a trapezoidal periodic load and study the behaviour of the response to the load changes. A simple setup was used, using a steel specimen loaded in the linear regime. A carefull test procedure was carried out in order to characterize the dissipation in a quasi-static periodic load. The experimental results show that the response delay to a ramp load depends on the durations of both the previous flat and the ramp itself

Optimal Visual Servoed Guidance Of Outdoor Autonomous Robotic Airships

This paper describes a visual servo control scheme for an outdoor autonomous airship in path following tasks. The visual based guidance takes full authority of the robotic airship and it is based on lines as image features, extracted from an on-board camera. An optimal controller is designed using the dynamic model of the system, which tackles the dynamics of the airship and the dynamics of the vision process. To prevent from losing image features during camera motion, to deal with noisy output measurements and modeling inaccuracies, a Kalman estimator was employed. The approach is validated through simulations using the AURORA project underactuated airship.1779784Bryson, A.E., Ho, Y.C., (1975) Applied Optimal Control, , Halsted Press, Washington D.C., EUADe Paiva, E.C., Bueno, S.S., Gomes, S.B.V., Ramos, J.J.G., Bergerman, M., A control system development environment for AURORA's semi-autonomous robotic airship (1999) Proceedings of the IEEE International Conference on Robotics and Automation, pp. 2328-2335. , Detroit, EUA, MayElfes, A., Bueno, S.S., Bergerman, M., Ramos, J.G., A semi-autonomous robotic airship for environment monitoring missions IEEE International Conference on Robotics and Automation, Leuven, Belgium, May 1998Espiau, B., Chaumette, F., Rives, P., A new approach to visual servoing in robotics (1992) IEEE Transactions on Robotics and Automation, 8 (3), pp. 313-326Gomes, S., Ramos, J.G., Airship dynamic modeling for autonomous operation IEEE International Conference on Robotics and Automation, Leuven, Belgium, May 1998Lewis, F.L., (1986) Optimal Estimation with an Introductory to Stochastic Control Theory, , John Wiley and Sons, IncPissard-Gibollet, R., Rives, P., Applying visual servoing techniques to control a mobile hand-eye system IEEE Int. Conference on Robotics and Automation, Nagoya, Japan, May 1995Rives, P., Borrelly, J., Visual servoing techniques applied to an underwater vehicle IEEE Int. Conf. on Robotics Ans Automation, Albuquerque, USA, April 1997Samson, C., Espiau, B., Le Borges, M., (1990) Robot Control: The Task Function Approach, , Oxford University Press, EUASilveira, G.F., Carvalho, J.R.H., Madrid, M.K., Bueno, S.S., Rives, P., Lateral control of an aerial unmanned robot using visual servoing techniques (2001) Proceedings of the IEEE 2nd Workshop on Robot Motion and Control, pp. 263-268. , Poland, OctoberSilveira, G.F., Carvalho, J.R.H., Madrid, M.K., Bueno, S.S., Rives, P., Towards vision guided navigation of autonomous aerial robots Anais do V Simpósio Brasileiro de Automação Inteligente, Canela/RS, Brasil, November 2001, , Article 1065Silveira, G.F., Carvalho, J.R.H., Shiroma, P.M., Rives, P., Bueno, S.S., Visual servo control of nonholonomic mobile robots (2001) Proceedings of the 16th Brazilian Congress of Mechanical Engineering, 15, pp. 333-341. , Uberlândia/MG, Brasil, NovemberStevens, B.L., Lewis, F.L., (1992) Aircraft Control and Simulation, , John Wiley and Sons, Inc., EUAVan Der Zwaan, S., Bernadino, A., Santos-Victor, J., Vision based station keeping and docking for an aerial blimp Proceedings of the IEEE International Conference on Intelligent Robots and Systems, 2000Zhang, H., Ostrowski, J.P., Visual servoing with dynamics: Control of an unmanned blimp (1999) Proceedings of the IEEE International Conference on Robotics and Automation, pp. 618-623. , Michigan, EUA, Ma

Homocysteinemia as a risk factor in early cerebrovascular disease

PURPOSE: To determine whether hyperhomocysteinemia represents a risk factor of early thrombotic cerebrovascular disease. METHOD: In a group of patients under 55 years of age (n = 33, 19 males) which had suffered a stroke from 3 months to 1 year before the study, defined by clinical criteria and presence of cerebral infarction confirmed by tomography, without history or predisposition to embolic disease. The patients were matched with a group of normal controls of checkup program, in terms of age, and sex. Patients and controls with a history of alcoholism, clinical or laboratory signs of renal or hepatic insufficiency or with a history of recent ingestion of Group B vitamins were excluded since these conditions would influence homocysteinemia levels. We measured the plasmatic basal homocysteinemia of patients and controls (HC) and 6 hours later a methionine overload of 0.1 g/Kg body weight (LOAD HC). RESULTS: Patients; Controls; Signific.; Age 46.0 +/- 7.7; 45.9 +/- 7.8; NS; Basal HC. 10.1 +/- 3.4; 8.5 +/- 1.7; p < 0.05; Load HC 28.0 +/- 7.6; 22.7 +/- 5.5; p < 0.01. CONCLUSION: In this study hyperhomocysteinemia appears as a risk factor for thrombotic cerebrovascular disease before the age of 55;-The measurement of homocysteinemia after the methionine loading test was more discriminative than the basal measurement;-A larger number of patients and controls will be necessary to establish the relative importance of homocysteinemia among other vascular risk factors in cerebrovascular disease.publishersversionpublishe

Expression profiling of genes involved in the biotrophic colonisation of Coffea arabica leaves by Hemileia vastatrix

Coffee Leaf Rust, caused by Hemileia vastatrix, is the most important disease of Arabica coffee (Coffea arabica), which prompts studies aimed at understanding the genetic basis of this pathogen as well as its complex interaction with the host. In this work, 11 genes, putatively involved in signalling, establishment and maintenance of biotrophy (transport and metabolism), were characterised, and their expression profiles during host infection were assessed by RT-qPCR in three compatible coffee-rust interactions comprising two different rust races. The profiles of two chitin deacetylases (CD) and a heterotrimeric G-protein alpha subunit transcripts suggest that these enzymes are involved in host-pathogen recognition and establishment of biotrophy at early stages of infection, and the late expression of the CD1 gene was also recorded. Different expression profiles were observed for a MAP kinase gene between the two rust races, suggesting that this gene may be involved in the differentiation of infection structures in a race-specific pattern. Two amino acid transporters, an invertase, a hexose transporter and a mannitol dehydrogenase presented expression profiles similar to those reported in other rust fungi, indicating a fairly conserved genetic programme related to host infection in rust fungi. The strong upregulation of a Uromyces fabae rust transferred protein 1 orthologous gene was observed in H. vastatrix in planta structures, suggesting that this gene may also play a role during the establishment and the maintenance of biotrophy in coffee leaves. Overall, our results provide valuable insights to the current understanding of the biotrophic interaction between H. vastatrix - C. arabica at the molecular level and will contribute to a reasoned and sustainable use of resistant genotypes