The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Teruo Shimmen - One of the best experts on this subject based on the ideXlab platform.
-
rhizoid differentiation in spirogyra Position Sensing by terminal cells
Plant and Cell Physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:;Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd 3+ or decrease in extracellular Ca 2+ resulted in inhibition of all
-
Rhizoid differentiation in Spirogyra: Position Sensing by terminal cells.
Plant & cell physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in Position Sensing by terminal cells.
Naoko Inoue - One of the best experts on this subject based on the ideXlab platform.
-
rhizoid differentiation in spirogyra Position Sensing by terminal cells
Plant and Cell Physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:;Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd 3+ or decrease in extracellular Ca 2+ resulted in inhibition of all
-
Rhizoid differentiation in Spirogyra: Position Sensing by terminal cells.
Plant & cell physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in Position Sensing by terminal cells.
Yoko Nagata - One of the best experts on this subject based on the ideXlab platform.
-
rhizoid differentiation in spirogyra Position Sensing by terminal cells
Plant and Cell Physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:;Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd 3+ or decrease in extracellular Ca 2+ resulted in inhibition of all
-
Rhizoid differentiation in Spirogyra: Position Sensing by terminal cells.
Plant & cell physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in Position Sensing by terminal cells.
Shinya Yamada - One of the best experts on this subject based on the ideXlab platform.
-
rhizoid differentiation in spirogyra Position Sensing by terminal cells
Plant and Cell Physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:;Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd 3+ or decrease in extracellular Ca 2+ resulted in inhibition of all
-
Rhizoid differentiation in Spirogyra: Position Sensing by terminal cells.
Plant & cell physiology, 2002Co-Authors: Naoko Inoue, Yoko Nagata, Shinya Yamada, Teruo ShimmenAbstract:Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal Position in a filament. In the present study, we have analyzed the mechanism for Position Sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal Position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in Position Sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in Position Sensing by terminal cells.
Stéphane Viollet - One of the best experts on this subject based on the ideXlab platform.
-
Hyperacute Edge and Bar Detection in a Bioinspired Optical Position Sensing Device
IEEE ASME Transactions on Mechatronics, 2014Co-Authors: Raphael JUSTON, Lubin Kerhuel, Nicolas Franceschini, Stéphane ViolletAbstract:We present an improved bioinspired optical Position Sensing device, in which insect-based retinal microscanning movements are used to detect and locate contrasting objects such as edges or bars. The active microvibrations imposed upon the retina endow the sensor with hyperacuity. For the sake of clarity, this is demonstrated here for a two-pixel sensor, but the same principle could be applied to all pairs of neighboring photosensors in a focal plane array. The sensor is able to detect an edge or a bar present within its small field of view (4 degrees) and locate it with a resolution (0.025 degrees) 160-fold finer than the static resolution imposed by the pixel spacing. The sensor features the novel ability to establish whether it is actually facing an edge or a bar, based on the phase difference between the sinusoidally modulated signals of its two photoreceptors. The visual processing algorithm involves simple linear filtering and purely arithmetic operations requiring few computational resources. The complete theoretical framework is presented here, including an analytical model for the microscanning sensor. This high-performance, low-cost angular Position Sensing device could have many applications in fields such as metrology, astronomy, robotics, automotive design, and aerospace.
-
A tiny lensless Position Sensing device for the tracking of active markers
2013Co-Authors: Thibaut Raharijaona, Raphael JUSTON, Paul Mignon, Stéphane ViolletAbstract:Active markers tracking is performed using an innovative insect-based visual sensor. Without any optics and a field-of-view of about 60°, our novel miniature visual sensor is able to locate flickering markers (LEDs) with accuracy much greater than the one dictated by the pixel pitch. With a size of only 1cm3 and a mass of only 0.33g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. This small cubic Position Sensing device is composed of only three photosensors placed on each side of the cube, making this sensor very cheap and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at high frequency (>1kHz) with a precision of only few degrees. The simplicity, small size, low mass, and low power consumption of this optical sensor make it suitable for many applications in the field of cooperative flight of unmanned aerial vehicles, swarm robotics and more generally robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative Position between the sensor and the infrared markers.
-
The VODKA sensor: a bio-inspired hyperacute optical Position Sensing device
IEEE Sensors Journal, 2012Co-Authors: Lubin Kerhuel, Stéphane Viollet, Nicolas FranceschiniAbstract:We have designed and built a simple optical sensor called Vibrating Optical Device for the Kontrol of Autonomous robots (VODKA), that was inspired by the "tremor" eye movements observed in many vertebrate and invertebrate animals. In the initial version presented here, the sensor relies on the repetitive micro-translation of a pair of photoreceptors set behind a small lens, and on the processing designed to locate a target from the two photoreceptor signals. The VODKA sensor, in which retinal micro-scanning movements are performed via a small piezo-bender actuator driven at a frequency of 40Hz, was found to be able to locate a contrasting edge with an outstandingly high resolution 900-fold greater than its static resolution (which is constrained by the interreceptor angle), regardless of the scanning law imposed on the retina. Hyperacuity is thus obtained at a very low cost, thus opening new vistas for the accurate visuo-motor control of robotic platforms. As an example, the sensor was mounted onto a miniature aerial robot that became able to track a moving target accurately by exploiting the robot's uncontrolled random vibrations as the source of its ocular microscanning movement. The simplicity, small size, low mass and low power consumption of this optical sensor make it highly suitable for many applications in the fields of metrology, astronomy, robotics, automotive, and aerospace engineering. The basic operating principle may also shed new light on the whys and wherefores of the tremor eye movements occurring in both animals and humans.
-
A miniature bio-inspired Position Sensing device for the control of micro-aerial robots
IEEE International Conference on Intelligent Robots and Systems, 2012Co-Authors: Raphael JUSTON, Stéphane ViolletAbstract:Here we present an example of a novel bio-inspired active vision system with a vibrating eye that can rotate freely by means of a miniature rotary piezo motor. Active micro-vibrations were applied to the eye by using an innovative micro-mechanism based on a tiny stepper motor. The hyperacuity of this inexpensive Position-Sensing device, which results from the active micro-vibrations, makes it capable of measuring the angular Position of a contrasting edge. Among the many miniature rotary actuators available, piezomotors are often used when small size, low mass, great accuracy and high dynamics are required. The newly off-the-shelf miniature ultrasonic piezomotor presented in this study along with its Position servo control system is supplied ready-integrated into a printed circuit board (PCB). The PCB Piezomotor (or PCBMotor) has many advantages, such as high torque (it requires no reducer), fast dynamics (the mechanical time constant is 3 ms), a low mass (1 gram) and a compact size (it is only 20 mm in diameter and 2.6 mm thick). The results of the tests conducted show that the performances of the PCBmotor connected to a custom-made miniature electronic driver make it a good alternative to the actuators classically used in robotic applications. In addition we present a simple visual processing, implemented onto a tiny microcontroller, composed of simple linear filtering and arithmetic operations. We show that our visual scanning sensor is a genuine Position Sensing device able to measure the relative angular Position of a visual object with only two pixels and very few computational resources.
-
IROS - A miniature bio-inspired Position Sensing device for the control of micro-aerial robots
2012 IEEE RSJ International Conference on Intelligent Robots and Systems, 2012Co-Authors: Raphael JUSTON, Stéphane ViolletAbstract:Here we present an example of a novel bio-inspired active vision system with a vibrating eye that can rotate freely by means of a miniature rotary piezo motor. Active micro-vibrations were applied to the eye by using an innovative micro-mechanism based on a tiny stepper motor. The hyperacuity of this inexpensive Position-Sensing device, which results from the active micro-vibrations, makes it capable of measuring the angular Position of a contrasting edge. Among the many miniature rotary actuators available, piezomotors are often used when small size, low mass, great accuracy and high dynamics are required. The newly off-the-shelf miniature ultrasonic piezomotor presented in this study along with its Position servo control system is supplied ready-integrated into a printed circuit board (PCB). The PCB Piezomotor (or PCBMotor) has many advantages, such as high torque (it requires no reducer), fast dynamics (the mechanical time constant is 3ms), a low mass (1gram) and a compact size (it is only 20mm in diameter and 2.6mm thick). The results of the tests conducted show that the performances of the PCBmotor connected to a custom-made miniature electronic driver make it a good alternative to the actuators classically used in robotic applications. In addition we present a simple visual processing, implemented onto a tiny microcontroller, composed of simple linear filtering and arithmetic operations. We show that our visual scanning sensor is a genuine Position Sensing device able to measure the relative angular Position of a visual object with only two pixels and very few computational resources.
