The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
K Antonelli - One of the best experts on this subject based on the ideXlab platform.
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the Ksi tentacle manipulator
International Conference on Robotics and Automation, 1995Co-Authors: G Immega, K AntonelliAbstract:Robotic tentacles provide an interesting alternative to conventional rigid-link robotic arms; in certain situations, they may even be more capable. Kinetic Sciences Inc. has developed a hybrid electric-pneumatic tentacular robot called the Ksi tentacle manipulator. It has variable compliance, can bend independently in two or more regions, and can extend to more than five times its contracted length. In total, the Tentacle has six degrees of freedom-or seven with the addition of a distal wrist-rotate joint. The Tentacle's unusual kinematics and inherent compliance demand new approaches to control. Three schemes are considered here: joystick-based teleoperation, inverse kinematics-based tendon length control, and machine vision-based fine position control. Under control, the Tentacle has broad potential in many applications, including teleoperated vacuuming and spray washing (for nuclear hot cell decontamination), general materials handling, agricultural harvesting, robotic refueling, and endoscopy.
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ICRA - The Ksi tentacle manipulator
Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995Co-Authors: G Immega, K AntonelliAbstract:Robotic tentacles provide an interesting alternative to conventional rigid-link robotic arms; in certain situations, they may even be more capable. Kinetic Sciences Inc. has developed a hybrid electric-pneumatic tentacular robot called the Ksi tentacle manipulator. It has variable compliance, can bend independently in two or more regions, and can extend to more than five times its contracted length. In total, the Tentacle has six degrees of freedom-or seven with the addition of a distal wrist-rotate joint. The Tentacle's unusual kinematics and inherent compliance demand new approaches to control. Three schemes are considered here: joystick-based teleoperation, inverse kinematics-based tendon length control, and machine vision-based fine position control. Under control, the Tentacle has broad potential in many applications, including teleoperated vacuuming and spray washing (for nuclear hot cell decontamination), general materials handling, agricultural harvesting, robotic refueling, and endoscopy.
Francisco Xavier Ribeiro Do Vale - One of the best experts on this subject based on the ideXlab platform.
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photosynthetic gas exchange in common bean submitted to foliar sprays of potassium silicate sodium molybdate and fungicide and infected with colletotrichum lindemuthianum
Journal of Phytopathology, 2015Co-Authors: Fabricio Avila Rodrigues, Leonora Rodriguez Polanco, Henrique Da Silva Silveira Duarte, Renata Sousa Resende, Francisco Xavier Ribeiro Do ValeAbstract:This study investigated whether foliar sprays of potassium silicate (Ksi), sodium molybdate (NaMo) or a combination of both (Ksi + NaMo), with or without the fungicide azoxystrobin (Azox), could reduce anthracnose symptoms, improve photosynthesis and increase yield. Two 2 × 4 factorial experiments, consisting of untreated or fungicide-treated plants sprayed with Ksi, NaMo or Ksi + NaMo were arranged in a randomized block design with three replications. The treatments were as follows: (i) Ksi; (ii) NaMo; (iii) Ksi + NaMo; (iv) Azox; (v) Azox + Ksi; (vi) Azox + NaMo; (vii) Azox + Ksi + NaMo; and (viii) control (no Ksi, NaMo or Azox). The Ksi, NaMo and Azox treatments were applied at the rates of 35 g/l, 90 g/ha and 120 g ai/ha, respectively. Ksi was applied at 20, 27, 40 and 55 days after sowing (das). NaMo was applied only at 27 das, whereas the fungicide was applied at 27, 40 and 55 das. The plants were inoculated with Colletotrichum lindemuthianum at 23 das. The anthracnose severity was reduced by 64.25% and yield increase by 156.2% in plants sprayed with fungicide compared with non-sprayed ones. The Ksi, NaMo and NaMo + Ksi applications reduced anthracnose severity by 31.8, 16.1 and 37.9%, respectively, while the yield increased by 16.8, 18.9 and 63.9%, respectively. There was no difference between treated and non-treated plants with Ksi with respect to the leaf gas exchange parameters Ci, E and gs. However, A significantly increased by 16.9% in plants treated with Azox. The A was not affected by Ksi or NaMo spray; however, it was significantly increased by 12.5% after spraying with NaMo + Ksi. In conclusion, bean plants treated with Si and Mo were associated with a decrease in anthracnose as well as an enhancement in photosynthesis activity under field conditions.
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management of anthracnose in common bean by foliar sprays of potassium silicate sodium molybdate and fungicide
Plant Disease, 2014Co-Authors: Leonora Rodriguez Polanco, Fabricio Avila Rodrigues, Henrique Da Silva Silveira Duarte, E N Moreira, Isaias Severino Cacique, L A Valente, R F Vieira, T J Paula, Francisco Xavier Ribeiro Do ValeAbstract:Polanco, L. R., Rodrigues, F. A., Moreira, E. N., Duarte, H. S. S., Cacique, I. S., Valente, L. A., Vieira, R. F., Paula Junior, T. J., and Vale, F. X. R. 2014. Management of anthracnose in common bean by foliar sprays of potassium silicate, sodium molybdate, and fungicide. Plant Dis. 98:84-89. This study aimed to determine whether foliar sprays of potassium silicate (Ksi), sodium molybdate (NaMo), or a combination of both (Ksi + NaMo), with or without the fungicide azoxystrobin (Azox), could reduce anthracnose symptoms and, consequently increase yield. Two two-by-four factorial experiments, consisting of untreated or fungicide treated, as well as sprays of Ksi, NaMo, Ksi + NaMo, and no spray (control), were arranged in a randomized block design with three replications. Treatments were as follows: treatment 1, Ksi spray; treatment 2, NaMo spray; treatment 3, Ksi + NaMo spray; treatment 4, Azox spray; treatment 5, Azox + Ksi spray; treatment 6, Azox + NaMo spray, treatment 7, Azox + Ksi + NaMo spray; and treatment 8, control (no Ksi, NaMo, or Azox). The Ksi, NaMo, and Azox treatments were sprayed at the rates of 35 g/liter, 90 g/ha, and 120 g a.i./ha, respectively. The Ksi was applied at 20, 27, 40, and 55 days after sowing (das). The NaMo was sprayed only at 27 das whereas the fungicide was sprayed at 27, 40, and 55 das. Plants were inoculated with Colletotrichum lindemuthianum at 23 das. Azox reduced the mean area under disease progress curve (AUDPC) by 63% and mean yield was increased by 150%. Similarly, the mean AUDPC was reduced by 29, 14, and 41% with Ksi, NaMo, and Ksi + NaMo sprays, respectively, while mean yield increased by 13, 20, and 47%, with Ksi, NaMo, or Ksi + NaMo sprays, respectively. The variables leaf area index (LAI), leaf area index duration (LAD), healthy leaf area duration (HAD), and radiation intercepted (RI) were not affected by Ksi spray. The values for the variables LAI, healthy leaf area index (HLAI), LAD, HAD, RI, intercepted radiation of the healthy leaf area, and healthy leaf area absorption were significantly increased as a result of NaMo spray. The results of the present study support the novel possibility of using a foliar spray of Ksi in association with NaMo to decrease anthracnose symptoms in bean plants and, consequently, achieve greater yield.
Eric Struyf - One of the best experts on this subject based on the ideXlab platform.
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Silicon Mobilization in Soils: the Broader Impact of Land Use
Silicon, 2019Co-Authors: Lúcia Barão, Floor Vandevenne, Ricardo Teixeira, Benedicta Ronchi, Dácil Unzué-belmonte, Eric StruyfAbstract:Dissolved Si (DSi) provision from land systems triggers diatom growth and CO_2 sequestration. Soils and ecosystems act as a Si “filter”, transforming DSi originated from mineral weathering into biogenic Si (BSi) after DSi uptake by plants, or into other pedogenic forms of Si (non-BSi). Land use changes the quantity of BSi and non-BSi pools along the soil profile. However, methods used to isolate Si pools include chemical extractions at high temperatures and alkaline environments and therefore are unable to provide information concerning the dissolution potential of BSi and non-BSi pools under normal conditions of temperature and pH. Here, we conducted a batch experiment where forest, pasture and cropland soil samples were mixed with water at 25 °C and pH 7. The soil samples were collected from a temperate land use gradient located in the Belgian Loess Belt. We measured dissolved Si and aluminium (Al) during 80 days. BSi and non-BSi pool contents along the soil profile were known, as they had been established previously through chemical extraction. Results show that BSi and non-BSi enriched samples present distinct Si and Al dissolution curves. While non-BSi pools contribute significantly with immediate availability of Si, BSi pools present an initial slow dissolution. Therefore, croplands that were depleted of phytoliths and had poorly organic horizons display higher concentrations of initial dissolved Si, while pastures and forests, where pedogenic pools dominate only at depths below 40 cm, have more limited initial Si release.
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Tracing silicon cycling in the Okavango Delta, a sub-tropical flood-pulse wetland using silicon isotopes
Geochimica et Cosmochimica Acta, 2014Co-Authors: Patrick J. Frings, Eric Struyf, Christina De La Rocha, Dimitri Van Pelt, Jonas Schoelynck, Mike Murray Hudson, Mangaliso J. Gondwe, Piotr Wolski, Keotsheple Mosimane, William GrayAbstract:Chemical weathering of silicate minerals releases elements into solution whereas the neoformation of secondary minerals works in the opposite direction, potentially confounding estimates of silicate weathering rates. Silicon isotopes (δ30Si) may be a useful tool to investigate these processes. Here, we present 82 δ30Si measurements from surface waters, pore waters, biogenic silica (BSi), clays, sand and vegetation from the Okavango Delta, Botswana, a freshwater sub-tropical, flood-pulse wetland. Hydrologically, the Okavango is dominated by evapotranspiration water losses to the atmosphere. It receives an annual pulse of water that inundates seasonal floodplains, while river baseflow is sufficient to maintain a permanent floodplain. δ30Si in dissolved silica (DSi) in surface waters along a 300km transect at near-peak flood show a limited range (0.36-1.19‰), implying the Delta is well buffered by a balance of processes adding and removing DSi from the surface water. A key control on DSi concentrations is the uptake, production of BSi and recycling of Si by aquatic vegetation, although the net isotopic effect is necessarily small since all BSi re-dissolves on short timescales. In the sediments, BSi δ30Si (n=30) ranges from -1.49‰ to +0.31‰ and during dissolution, residual BSi tends towards higher δ30Si. The data permit a field-based estimate of the fractionation associated with BSi dissolution, ε30 BSi-DSi=-0.26‰, though it is unclear if this is an artefact of the process of dissolution. Clay δ30Si ranges from -0.97‰ to +0.10‰, (n=15, mean=-0.31‰) and include the highest values yet published, which we speculate may be due to an equilibrium isotope effect during diagenetic transformation of BSi. Two key trends in surface water DSi δ30Si merit further examination: declining δ30Si in an area roughly corresponding to the permanent floodplains despite net DSi removal, and increasing δ30Si in the area corresponding to the seasonal floodplains. We infer that evaporative enrichment of surface waters creates two contrasting regimes. Chemical weathering of low δ30Si phases releases low δ30Si DSi in the relatively dilute waters of the permanent floodplains, whereas silicon removal via clay formation or vegetation uptake is the dominant process in the more enriched, seasonal floodplains.
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Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration
Biogeochemistry, 2014Co-Authors: Patrick J. Frings, Wim Clymans, Torben L Lauridsen, Eric Struyf, Erik Jeppesen, Daniel J ConleyAbstract:Weathering of silicate minerals releases dissolved silicate (DSi) to the soil-vegetation system. Accumulation and recycling of this DSi by terrestrial ecosystems creates a pool of reactive Si on the continents that buffers DSi export to the ocean. Human perturbations to the functioning of the buffer have been a recent research focus, yet a common assumption is that the continental Si cycle is at steady-state. However, we have no good idea of the timescales of ecosystem Si pool equilibration with their environments. A review of modelling and geochemical considerations suggests the modern continental Si cycle is in fact characterised in the long-term by an active accumulation of reactive Si, at least partially attributable to lakes and reservoirs. These lentic systems accumulate Si via biological conversion of DSi to biogenic silica (BSi). An analysis of new and published data for nearly 700 systems is presented to assess their contribution to the accumulating continental pool. Surface sediment BSi concentrations ( n = 692) vary between zero and >60 % SiO_2 by weight, apparently independently of lake size, location or water chemistry. Using sediment core BSi accumulation rates ( n = 109), still no relationships are found with lake or catchment parameters. However, issues associated with single-core accumulation rates should in any case preclude their use in elemental accumulation calculations. Based on lake/reservoir mass-balances ( n = 34), our best global-scale estimate of combined lake and reservoir Si retention is 1.53 TMol year^−1, or 21–27 % of river DSi export. Again, no scalable relationships are apparent, suggesting Si retention is a complex process that varies from catchment to catchment. The lake Si sink has implications for estimation of weathering flux generation from river chemistry. The size of the total continental Si pool is poorly constrained, as is its accumulation rate, but lakes clearly contribute substantially. A corollary to this emerging understanding is that the flux and isotopic composition of DSi delivered to the ocean has likely varied over time, partly mediated by a fluctuating continental pool, including in lakes.
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Emerging understanding of the ecosystem silica filter
Biogeochemistry, 2012Co-Authors: Eric Struyf, Daniel J ConleyAbstract:The annual fixation of dissolved Si (DSi) into terrestrial vegetation has been estimated to range from 60 to 200 Tmole, or 10–40 times more than the yearly export of DSi and biogenic Si (BSi) from the terrestrial geobiosphere to the coastal zone. Ecosystems form a large filter between primary mobilization of DSi from silicate weathering and its eventual export to the oceans, and a large reservoir of BSi accumulates in aquatic and terrestrial ecosystems. Although a number of synthesis activities within the last decade have discussed biological transformations in the terrestrial Si cycle, the timescales at which BSi is stored and recycled within ecosystems, BSi persistence and reactivity throughout soil profiles, the dependence of the BSi storage and recycling on ecological processes, the feedbacks to hydrology, the interaction with man’s activities and ultimately the global relevance in Si budgets are poorly constrained. Here we discuss 5 key controls on the ability of ecosystems to filter and control the export of DSi: ecosystem biodiversity, BSi dissolution rates and reactivity, hydrology, interaction with the geosphere and anthropogenic impacts. These controls need to be further studied to better quantify the global and local importance of the terrestrial biogeochemical Si cycle and specifically the BSi reservoir in ecosystems.
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a trade off between dissolved and amorphous silica transport during peak flow events scheldt river basin belgium impacts of precipitation intensity on terrestrial si dynamics in strongly cultivated catchments
Biogeochemistry, 2011Co-Authors: Adriaan Smis, Wim Clymans, Eric Struyf, Stefan Van Damme, Bas Van Wesemael, Elisabeth Frot, Floor Vandevenne, Thomas Van Hoestenberghe, Gerard Govers, Patrick MeireAbstract:Amorphous, biogenic Si (ASi) is stored in large amounts in terrestrial ecosystems. The study of terrestrial ASi mobilization remains in the pioneer research stage: most Si budget studies have not included the biogenic amorphous Si stock and fluxes. This hampers our ability to accurately quantify terrestrial mobilization of Si, which is—through ocean carbon burial and CO2 uptake during terrestrial Si weathering—intricately linked to global carbon budgets. We studied detailed concentration and load patterns of dissolved (DSi) and ASi during several high-discharge events in eight first-order river basins. Based on high frequency discharge measurements and concurrent analysis of ASi and DSi concentrations at base flow and during intense precipitation events, we were able to attribute a percentage of yearly ASi and DSi fluxes to both base flow and precipitation event related surface run-off. Our results show ASi and DSi concentrations in upstream river basins to be intricately linked to each other and to discharge, and ASi transport constitutes an important part to the total transport of Si even through first-order river basins (up to 40%). Based on our observations, increased occurrence of peak-discharge events with global climatic changes, and lowered importance of base flow, will coincide with drastic changes in ASi and DSi dynamics in the river continuum. Our work clearly shows ASi dynamics should be incorporated in global Si budgets now, even in low-order small river basins.
Daniel J Conley - One of the best experts on this subject based on the ideXlab platform.
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Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration
Biogeochemistry, 2014Co-Authors: Patrick J. Frings, Wim Clymans, Torben L Lauridsen, Eric Struyf, Erik Jeppesen, Daniel J ConleyAbstract:Weathering of silicate minerals releases dissolved silicate (DSi) to the soil-vegetation system. Accumulation and recycling of this DSi by terrestrial ecosystems creates a pool of reactive Si on the continents that buffers DSi export to the ocean. Human perturbations to the functioning of the buffer have been a recent research focus, yet a common assumption is that the continental Si cycle is at steady-state. However, we have no good idea of the timescales of ecosystem Si pool equilibration with their environments. A review of modelling and geochemical considerations suggests the modern continental Si cycle is in fact characterised in the long-term by an active accumulation of reactive Si, at least partially attributable to lakes and reservoirs. These lentic systems accumulate Si via biological conversion of DSi to biogenic silica (BSi). An analysis of new and published data for nearly 700 systems is presented to assess their contribution to the accumulating continental pool. Surface sediment BSi concentrations ( n = 692) vary between zero and >60 % SiO_2 by weight, apparently independently of lake size, location or water chemistry. Using sediment core BSi accumulation rates ( n = 109), still no relationships are found with lake or catchment parameters. However, issues associated with single-core accumulation rates should in any case preclude their use in elemental accumulation calculations. Based on lake/reservoir mass-balances ( n = 34), our best global-scale estimate of combined lake and reservoir Si retention is 1.53 TMol year^−1, or 21–27 % of river DSi export. Again, no scalable relationships are apparent, suggesting Si retention is a complex process that varies from catchment to catchment. The lake Si sink has implications for estimation of weathering flux generation from river chemistry. The size of the total continental Si pool is poorly constrained, as is its accumulation rate, but lakes clearly contribute substantially. A corollary to this emerging understanding is that the flux and isotopic composition of DSi delivered to the ocean has likely varied over time, partly mediated by a fluctuating continental pool, including in lakes.
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Emerging understanding of the ecosystem silica filter
Biogeochemistry, 2012Co-Authors: Eric Struyf, Daniel J ConleyAbstract:The annual fixation of dissolved Si (DSi) into terrestrial vegetation has been estimated to range from 60 to 200 Tmole, or 10–40 times more than the yearly export of DSi and biogenic Si (BSi) from the terrestrial geobiosphere to the coastal zone. Ecosystems form a large filter between primary mobilization of DSi from silicate weathering and its eventual export to the oceans, and a large reservoir of BSi accumulates in aquatic and terrestrial ecosystems. Although a number of synthesis activities within the last decade have discussed biological transformations in the terrestrial Si cycle, the timescales at which BSi is stored and recycled within ecosystems, BSi persistence and reactivity throughout soil profiles, the dependence of the BSi storage and recycling on ecological processes, the feedbacks to hydrology, the interaction with man’s activities and ultimately the global relevance in Si budgets are poorly constrained. Here we discuss 5 key controls on the ability of ecosystems to filter and control the export of DSi: ecosystem biodiversity, BSi dissolution rates and reactivity, hydrology, interaction with the geosphere and anthropogenic impacts. These controls need to be further studied to better quantify the global and local importance of the terrestrial biogeochemical Si cycle and specifically the BSi reservoir in ecosystems.
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riverine contribution of biogenic silica to the oceanic silica budget
Limnology and Oceanography, 1997Co-Authors: Daniel J ConleyAbstract:Biological uptake of dissolved silicate (DSi) and formation of biogenic silica (BSi) during diatom growth modifies the form of Si carried from the continents to the world ocean. Significant concentrations of BSi, averaging 28.0 μmol L -1 , are found in all sizes of rivers. The global contribution of BSi carried by rivers was estimated as 1.05 ± 0.20 Tmol Si year -1 . Combined with the global mean riverine DSi concentration of 150 μmol liter -1 , 16% of the gross riverine Si load is delivered to the world ocean as BSi. Most of this BSi would be remobilized by dissolution in marine environments. These results demonstrate that the contribution of biogenic silica carried in suspension by rivers is an important component in the world ocean Si budget that has not been recognized previously.
G Immega - One of the best experts on this subject based on the ideXlab platform.
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the Ksi tentacle manipulator
International Conference on Robotics and Automation, 1995Co-Authors: G Immega, K AntonelliAbstract:Robotic tentacles provide an interesting alternative to conventional rigid-link robotic arms; in certain situations, they may even be more capable. Kinetic Sciences Inc. has developed a hybrid electric-pneumatic tentacular robot called the Ksi tentacle manipulator. It has variable compliance, can bend independently in two or more regions, and can extend to more than five times its contracted length. In total, the Tentacle has six degrees of freedom-or seven with the addition of a distal wrist-rotate joint. The Tentacle's unusual kinematics and inherent compliance demand new approaches to control. Three schemes are considered here: joystick-based teleoperation, inverse kinematics-based tendon length control, and machine vision-based fine position control. Under control, the Tentacle has broad potential in many applications, including teleoperated vacuuming and spray washing (for nuclear hot cell decontamination), general materials handling, agricultural harvesting, robotic refueling, and endoscopy.
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ICRA - The Ksi tentacle manipulator
Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995Co-Authors: G Immega, K AntonelliAbstract:Robotic tentacles provide an interesting alternative to conventional rigid-link robotic arms; in certain situations, they may even be more capable. Kinetic Sciences Inc. has developed a hybrid electric-pneumatic tentacular robot called the Ksi tentacle manipulator. It has variable compliance, can bend independently in two or more regions, and can extend to more than five times its contracted length. In total, the Tentacle has six degrees of freedom-or seven with the addition of a distal wrist-rotate joint. The Tentacle's unusual kinematics and inherent compliance demand new approaches to control. Three schemes are considered here: joystick-based teleoperation, inverse kinematics-based tendon length control, and machine vision-based fine position control. Under control, the Tentacle has broad potential in many applications, including teleoperated vacuuming and spray washing (for nuclear hot cell decontamination), general materials handling, agricultural harvesting, robotic refueling, and endoscopy.
