866 resultados para underwater robot localization
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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End users develop more software than any other group of programmers, using software authoring devices such as e-mail filtering editors, by-demonstration macro builders, and spreadsheet environments. Despite this, there has been little research on finding ways to help these programmers with the dependability of their software. We have been addressing this problem in several ways, one of which includes supporting end-user debugging activities through fault localization techniques. This paper presents the results of an empirical study conducted in an end-user programming environment to examine the impact of two separate factors in fault localization techniques that affect technique effectiveness. Our results shed new insights into fault localization techniques for end-user programmers and the factors that affect them, with significant implications for the evaluation of those techniques.
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In this paper, a cross-layer solution for packet size optimization in wireless sensor networks (WSN) is introduced such that the effects of multi-hop routing, the broadcast nature of the physical wireless channel, and the effects of error control techniques are captured. A key result of this paper is that contrary to the conventional wireless networks, in wireless sensor networks, longer packets reduce the collision probability. Consequently, an optimization solution is formalized by using three different objective functions, i.e., packet throughput, energy consumption, and resource utilization. Furthermore, the effects of end-to-end latency and reliability constraints are investigated that may be required by a particular application. As a result, a generic, cross-layer optimization framework is developed to determine the optimal packet size in WSN. This framework is further extended to determine the optimal packet size in underwater and underground sensor networks. From this framework, the optimal packet sizes under various network parameters are determined.
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The elimination of all external incisions is an important step in reducing the invasiveness of surgical procedures. Natural Orifice Translumenal Endoscopic Surgery (NOTES) is an incision-less surgery and provides explicit benefits such as reducing patient trauma and shortening recovery time. However, technological difficulties impede the widespread utilization of the NOTES method. A novel robotic tool has been developed, which makes NOTES procedures feasible by using multiple interchangeable tool tips. The robotic tool has the capability of entering the body cavity through an orifice or a single incision using a flexible articulated positioning mechanism and once inserted is not constrained by incisions, allowing for visualization and manipulations throughout the cavity. Multiple interchangeable tool tips of the robotic device initially consist of three end effectors: a grasper, scissors, and an atraumatic Babcock clamp. The tool changer is capable of selecting and switching between the three tools depending on the surgical task using a miniature mechanism driven by micro-motors. The robotic tool is remotely controlled through a joystick and computer interface. In this thesis, the following aspects of this robotic tool will be detailed. The first-generation robot is designed as a conceptual model for implementing a novel mechanism of switching, advancing, and controlling the tool tips using two micro-motors. It is believed that this mechanism achieves a reduction in cumbersome instrument exchanges and can reduce overall procedure time and the risk of inadvertent tissue trauma during exchanges with a natural orifice approach. Also, placing actuators directly at the surgical site enables the robot to generate sufficient force to operate effectively. Mounting the multifunctional robot on the distal end of an articulating tube provides freedom from restriction on the robot kinematics and helps solve some of the difficulties otherwise faced during surgery using NOTES or related approaches. The second-generation multifunctional robot is then introduced in which the overall size is reduced and two arms provide 2 additional degrees of freedom, resulting in feasibility of insertion through the esophagus and increased dexterity. Improvements are necessary in future iterations of the multifunctional robot; however, the work presented is a proof of concept for NOTES robots capable of abdominal surgical interventions.
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ComN (YrzD) is a small, 98-amino-acid protein recently shown to be involved in the posttranscriptional control of the late competence comE operon in Bacillus subtilis. We show here that ComN localizes to the division site and cell poles in a DivIVA-dependent fashion. Yeast two-hybrid and glutathione S-transferase pulldown experiments showed that ComN interacts directly with DivIVA. ComN is not essential for the polar assembly of the core competence DNA uptake machinery. Nevertheless, polar localization of ComN should play some role in competence acquisition because delocalization of ComN leads to a small reduction in competence efficiency. We found that ComN promotes the accumulation of its target comE mRNA to septal and polar sites. Thus, we speculate that localized translation of ComE proteins may be required for efficient competence development. Our results underscore the versatility of DivIVA as a promoter of the differentiation of bacterial poles and demonstrate that the repertoire of polarly localized molecules in B. subtilis is broad, including a regulator of gene expression and its target mRNA. Moreover, our findings suggest that mRNA localization may play a role in the subcellular organization of bacteria.
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Arthrogryposisrenal dysfunctioncholestasis (ARC) syndrome is a rare autosomal recessive multisystem disorder caused by mutations in vacuolar protein sorting 33 homologue B (VPS33B) and VPS33B interacting protein, apicalbasolateral polarity regulator (VIPAR). Cardinal features of ARC include congenital joint contractures, renal tubular dysfunction, cholestasis, severe failure to thrive, ichthyosis, and a defect in platelet alpha-granule biogenesis. Most patients with ARC do not survive past the first year of life. We report two patients presenting with a mild ARC phenotype, now 5.5 and 3.5 years old. Both patients were compound heterozygotes with the novel VPS33B donor splice-site mutation c.1225+5G>C in common. Immunoblotting and complementary DNA analysis suggest expression of a shorter VPS33B transcript, and cell-based assays show that c.1225+5G>C VPS33B mutant retains some ability to interact with VIPAR (and thus partial wild-type function). This study provides the first evidence of genotypephenotype correlation in ARC and suggests that VPS33B c.1225+5G>C mutation predicts a mild ARC phenotype. We have established an interactive online database for ARC (https://grenada.lumc.nl/LOVD2/ARC) comprising all known variants in VPS33B and VIPAR. Also included in the database are 15 novel pathogenic variants in VPS33B and five in VIPAR. Hum Mutat 33:16561664, 2012. (c) 2012 Wiley Periodicals, Inc.
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Background: The urethrovesical anastomosis is a particular challenging step of robot assisted radical prostatectomy (RARP). Failure to achieve a watertight anastomosis is associated with postoperative urinary leak and its consequences, which include paralytic ileus, prolonged catheterization, urinary peritonitis and possibly re-intervention. The bidirectional barbed suture is a new technology that may lead to improve the quality of the urethrovesical anastomosis. Objective: To present our surgical technique of urethrovesical anastomosis, bladder neck reconstruction and posterior reconstruction, using a bidirectional barbed suture. Material and methods: The bladder neck reconstruction, posterior reconstruction and vesicourethral anastomosis were performed using a 2-0 synthetic absorbable bidirectional monofilament barbed suture Results: All cases were finished successfully without major complication or conversion to laparoscopic or open surgery. Conclusion: The authors successfully modified their RARP technique to take advantage of the properties of the bidirectional barbed suture. Comparative studies that evaluate objective outcomes such as leakage rates and operative time are needed to definitely establish the benefits of this device in comparison to the traditional absorbable monofilament. (C) 2011 AEU. Published by Elsevier Espana, S.L. All rights reserved.
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Recently, a nongenomic cytotoxic component of the chemotherapeutic agent tamoxifen (TAM) has been identified that predominantly triggers mitochondrial events. The present study delineates the intracellular fate of TAM and studies its interaction with a spectrum of cell homeostasis modulators primarily relevant to mitochondria. The subcellular localization of TAM was assessed by confocal fluorescence microscopy. The effect of the modulators on TAM cytotoxicity was assessed by standard MTT assays. Our findings show that in estrogen receptor positive MCF7 breast adenocarcinoma cells and DU145 human prostate cancer cells, TAM largely accumulates in the mitochondria and endoplasmic reticulum, but not lysosomes. Our results further demonstrate that in MCF7, but not in DU145 cells, mitochondrial electron transport chain complex I and III inhibitors exacerbate TAM toxicity with an order of potency of myxothiazol = stigmatellin > rotenone > antimycin A, suggesting a cell-specific cytotoxic interplay between mitochondrial complex I and III function and TAM action.
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By combining first-principles electronic structure calculations and existing time-differential gamma-gamma perturbed-angular-correlation experiments we studied the site localization, the local environment, and the electronic structure of Cd impurities in sapphire (alpha-Al2O3) single crystals in different charged states. The ab initio calculations were performed with the full-potential augmented plane wave plus local orbitals method and the projector augmented wave method. Comparing the calculated electric-field-gradient tensor at the Cd nuclei in the alpha-Al2O3 host lattice and the corresponding available experimental values, we have seen that it is equally possible for Cd to replace an Al atom (in a negative charge state) or to be placed in an interstitial site (in a neutral charge state). To finally address the issue of the Cd impurity localization, we performed formation energy calculations. These results have shown that Cd placed in the substitutional Al site, in the negatively charged state, is the most probable configuration.
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Introduction: The objective of the study was to evaluate the ability of large-volume cone-beam computed tomography (CBCT) to detect horizontal root fracture and to test the influence of a metallic post. Methods: Through the examination of 40 teeth by large-volume CBCT (20-cm height and 15-cm diameter cylinder) at 0.2-mm voxel resolution, 2 observers analyzed the samples for the presence and localization of horizontal root fracture. Results: The values of accuracy in the groups that had no metallic post ranged from 33%-68%, whereas for the samples with the metallic post, values showed a wide variation (38%-83%). Intraobserver agreement showed no statistically significant difference between the groups with/without metallic post; both ranged from very weak to weak (kappa, 0.09-0.369). Conclusions: The low accuracy and low intraobserver and interobserver agreement reflect the difficulty in performing an adequate diagnosis of horizontal root fractures through a large-volume CBCT by using a small voxel reconstruction. (J Endod 2012;38:856-859)
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Inspection for corrosion of gas storage spheres at the welding seam lines must be done periodically. Until now this inspection is being done manually and has a high cost associated to it and a high risk of inspection personel injuries. The Brazilian Petroleum Company, Petrobras, is seeking cost reduction and personel safety by the use of autonomous robot technology. This paper presents the development of a robot capable of autonomously follow a welding line and transporting corrosion measurement sensors. The robot uses a pair of sensors each composed of a laser source and a video camera that allows the estimation of the center of the welding line. The mechanical robot uses four magnetic wheels to adhere to the sphere's surface and was constructed in a way that always three wheels are in contact with the sphere's metallic surface which guarantees enough magnetic atraction to hold the robot in the sphere's surface all the time. Additionally, an independently actuated table for attaching the corrosion inspection sensors was included for small position corrections. Tests were conducted at the laboratory and in a real sphere showing the validity of the proposed approach and implementation.
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A semi-autonomous unmanned underwater vehicle (UUV), named LAURS, is being developed at the Laboratory of Sensors and Actuators at the University of Sao Paulo. The vehicle has been designed to provide inspection and intervention capabilities in specific missions of deep water oil fields. In this work, a method of modeling and identification of yaw motion dynamic system model of an open-frame underwater vehicle is presented. Using an on-board low cost magnetic compass sensor the method is based on the utilization of an uncoupled 1-DOF (degree of freedom) dynamic system equation and the application of the integral method which is the classical least squares algorithm applied to the integral form of the dynamic system equations. Experimental trials with the actual vehicle have been performed in a test tank and diving pool. During these experiments, thrusters responsible for yaw motion are driven by sinusoidal voltage signal profiles. An assessment of the feasibility of the method reveals that estimated dynamic system models are more reliable when considering slow and small sinusoidal voltage signal profiles, i.e. with larger periods and with relatively small amplitude and offset.