Why do animals have so many receptors? The role of multiple chemosensors in animal perception.
(25/1601)
Many animals have an abundance and diverse assortment of peripheral sensors, both across and within sensory modalities. Multiple sensors offer many functional advantages to an animal's ability to perceive and respond to environmental signals. Advantages include extending the ability to detect and determine the spatial distribution of stimuli, improving the range and accuracy of discrimination among stimuli of different types and intensities, increasing behavioral sensitivity to stimuli, ensuring continued sensory capabilities when the probability of damage or other loss of function to some sensors is high, maintaining sensory function over the entire sensory surface during development and growth, and increasing the richness of behavioral output to sensory stimulation. In this paper, we use the crustacean chemosensory system as the primary example to discuss these functions of multiple sensors. These principles may be applicable to the function of autonomous robots and should be considered in their design. (+info)
Landing strategies in honeybees, and possible applications to autonomous airborne vehicles.
(26/1601)
Insects, being perhaps more reliant on image motion cues than mammals or higher vertebrates, are proving to be an excellent organism in which to investigate how information on optic flow is exploited to guide locomotion and navigation. This paper describes one example, illustrating how bees perform grazing landings on a flat surface. A smooth landing is achieved by a surprisingly simple and elegant strategy: image velocity is held constant as the surface is approached, thus automatically ensuring that flight speed is close to zero at touchdown. No explicit knowledge of flight speed or height above the ground is necessary. The feasibility of this landing strategy is tested by implementation in a robotic gantry, and its applicability to autonomous airborne vehicles is discussed. (+info)
Plume-tracking robots: a new application of chemical sensors.
(27/1601)
Many animals have the ability to search for odor sources by tracking their plumes. Some of the key features of this search behavior have been successfully transferred to robot platforms, although the capabilities of animals are still beyond the current level of sensor technologies. The examples described in this paper are (1) incorporating into a wheeled robot the upwind surges and casting used by moths in tracking pheromone plumes, (2) extracting useful information from the response patterns of a chemical sensor array patterned after the spatially distributed chemoreceptors of some animals, and (3) mimicking the fanning behavior of silkworm moths to enhance the reception of chemical signals by drawing molecules from one direction. The achievements so far and current efforts are reviewed to illustrate the steps to be taken toward future development of this technology. (+info)
Sensory architectures for biologically inspired autonomous robotics.
(28/1601)
Engineers have a lot to gain from studying biology. The study of biological neural systems alone provides numerous examples of computational systems that are far more complex than any man-made system and perform real-time sensory and motor tasks in a manner that humbles the most advanced artificial systems. Despite the evolutionary genesis of these systems and the vast apparent differences between species, there are common design strategies employed by biological systems that span taxa, and engineers would do well to emulate these strategies. However, biologically-inspired computational architectures, which are continuous-time and parallel in nature, do not map well onto conventional processors, which are discrete-time and serial in operation. Rather, an implementation technology that is capable of directly realizing the layered parallel structure and nonlinear elements employed by neurobiology is required for power- and space-efficient implementation. Custom neuromorphic hardware meets these criteria and yields low-power dedicated sensory systems that are small, light, and ideal for autonomous robot applications. As examples of how this technology is applied, this article describes both a low-level neuromorphic hardware emulation of an elementary visual motion detector, and a large-scale, system-level spatial motion integration system. (+info)
Prospective clinical trial of robotically assisted endoscopic coronary grafting with 1-year follow-up.
(29/1601)
OBJECTIVE: To follow up in prospective fashion patients with coronary artery anastomoses completed endoscopically with robotic assistance. The robotic system was evaluated for safety and its effectiveness in completing microsurgical coronary anastomoses. SUMMARY BACKGROUND DATA: Recently there has been an interest in using robotics and computers to enhance the surgeon's ability to perform endoscopic cardiac surgery. This interest has stemmed from the rapid advancement of technology and the desire to make cardiac surgery less invasive. Using traditional endoscopic instruments, it has not been possible to perform coronary surgery. METHODS: Nineteen patients underwent robotically assisted endoscopic coronary artery bypass grafting of the left internal thoracic artery (LITA) to the left anterior descending artery (LAD). Two robotic instruments and one endoscopic camera were placed through three 5-mm ports. A robotic system was used to construct the LITA-LAD anastomosis. All other required grafts were completed by conventional techniques. RESULTS: Seventeen LITA-LAD grafts (89%) had adequate intraoperative flow. The mean LITA-LAD graft flow was 38.5 +/- 5 mL/min. At 8 weeks, LITA-LAD grafts were assessed by angiography and showed 100% patency with thrombolysis in myocardial infarction (TIMI) I flow. At a mean follow-up of 17 +/- 4.2 months, all patients were NYHA class I and there were no adverse cardiac events. CONCLUSIONS: The results from the first prospective clinical trial of robotically assisted endoscopic coronary bypass surgery in the United States showed favorable short-term outcomes with no adverse events. Robotic assistance is an enabling technology allowing the performance of endoscopic coronary anastomoses. (+info)
Detection of herpes simplex virus DNA in genital and dermal specimens by LightCycler PCR after extraction using the IsoQuick, MagNA Pure, and BioRobot 9604 methods.
(30/1601)
We evaluated two automated systems, MagNA Pure (Roche Molecular Biochemicals, Indianapolis, Ind.) and BioRobot 9604 (Qiagen, Inc., Chatsworth, Calif.) as effective replacements for the manual IsoQuick method (Orca Research, Inc., Bothell, Wash.) for extraction of herpes simplex virus (HSV) DNA from dermal and genital tract specimens prior to analysis by LightCycler PCR. Of 198 specimens (152 genital, 46 dermal), 92 (46.2%) were positive for HSV DNA by LightCycler PCR after automated extraction of specimens with either the MagNA Pure or BioRobot 9604 instrument. The manual IsoQuick method yielded HSV DNA (total n = 95) from three additional specimens that were negative by the automated method (P = 0.25, sign test). Although the mean numbers of LightCycler PCR cycles required to reach positivity differed statistically significantly among all three of the methods of extraction, the estimated means differed by no more than 1.5 cycles (P < 0.05). Seventy (76%) of the 92 specimens that were LightCycler PCR positive by all three extraction methods were also positive by shell vial cell culture assay. HSV DNA was detected by a lower LightCycler PCR cycle number (26.1 cycles) in specimens culture positive for the virus than in culture-negative samples (33.3 cycles) (P < 0.0001). The manual IsoQuick and automated MagNA Pure and BioRobot 9604 methods provide standardized, reproducible extraction of HSV DNA for LightCycler PCR. The decision to implement a manual versus an automated procedure depends on factors such as costs related to the number of specimens processed rather than on the minimal differences in the technical efficiency of extraction of nucleic acids among these methods. (+info)
Telerobotic laparoscopic cholecystectomy: initial clinical experience with 25 patients.
(31/1601)
OBJECTIVE: To determine the safety and feasibility of performing telerobotic laparoscopic cholecystectomies. This will serve as a preliminary step toward the integration of computer-rendered three-dimensional preoperative imaging studies of anatomy and pathology onto the patient's own anatomy during surgery. SUMMARY BACKGROUND DATA: Computer-assisted surgery (CAS) increases the surgeon's dexterity and precision during minimally invasive surgery, especially when using microinstruments. Clinical trials have shown the improved microsurgical precision afforded by CAS in the minimally invasive setting in cardiac and gynecologic surgery. Future applications would allow integration of preoperative data and augmented-reality simulation onto the actual procedure. METHODS: Beginning in September 1999, CAS was used to perform cholecystectomies on 25 patients at a single medical center in this nonrandomized, prospective study. The operations were performed by one of two surgeons who had previous laboratory experience using the computer interface. The entire dissection was performed by the surgeon, who remained at a distance from the patient but in the same operating room. The operation was evaluated according to time of dissection, time of assembly/disassembly of robot, complications, immediate postoperative course, and short-term follow-up. RESULTS: Twenty of the 25 patients had symptomatic cholelithiasis, 1 had a gallbladder polyp, and 4 had acute cholecystitis. Twenty-four of the 25 laparoscopic cholecystectomies were successfully completed by CAS. There was one conversion to conventional laparoscopic cholecystectomy. Set-up and takedown of the robotic arms took a median of 18 minutes. The median operative time for dissection and the overall operative time were 25 and 108 minutes, respectively. There were no intraoperative complications. There was one postoperative complication of a suspected pulmonary embolus, which was treated with anticoagulation. All patients were tolerating diet at discharge. CONCLUSIONS: Laparoscopic cholecystectomy performed by CAS is safe and feasible, with operative times and patient recovery similar to those of conventional laparoscopy. At present, CAS cholecystectomy offers no obvious advantages to patients, but the potential advantages of CAS lie in its ability to convert the surgical act into digitized data. This digitized format can then interface with other forms of digitized data, such as pre- or intraoperative imaging studies, or be transmitted over a distance. This has the potential to revolutionize the way surgery is performed. (+info)
Efficacy of navigation in skull base surgery using composite computer graphics of magnetic resonance and computed tomography images.
(32/1601)
The efficacy of a neurosurgical navigation system using three-dimensional composite computer graphics (CGs) of magnetic resonance (MR) and computed tomography (CT) images was evaluated in skull base surgery. Three-point transformation was used for integration of MR and CT images. MR and CT image data were obtained with three skin markers placed on the patient's scalp. Volume-rendering manipulations of the data produced three-dimensional CGs of the scalp, brain, and lesions from the MR images, and the scalp and skull from the CT. Composite CGs of the scalp, skull, brain, and lesion were created by registering the three markers on the three-dimensional rendered scalp images obtained from MR imaging and CT in the system. This system was used for 14 patients with skull base lesions. Three-point transformation using three-dimensional CGs was easily performed for multimodal registration. Simulation of surgical procedures on composite CGs aided in comprehension of the skull base anatomy and selection of the optimal approaches. Intraoperative navigation aided in determination of actual spatial position in the skull base and the optimal trajectory to the tumor during surgical procedures. (+info)