7,130 research outputs found

    Space Applications of Automation, Robotics and Machine Intelligence Systems (ARAMIS), phase 2. Volume 1: Telepresence technology base development

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    The field of telepresence is defined, and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA's plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies over the next decade are included. Several space projects are examined in detail to determine what capabilities are required of a telepresence system in order to accomplish various tasks, such as servicing and assembly. The key operational and technological areas are identified, conclusions and recommendations are made for further research, and an example developmental program is presented, leading to an operational telepresence servicer

    Space applications of Automation, Robotics And Machine Intelligence Systems (ARAMIS). Volume 3, phase 2: Executive summary

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    The field of telepresence is defined, and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA's plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies are included. Several space projects are examined in detail to determine what capabilities are required of a telepresence system in order to accomplish various tasks, such as servicing and assembly. The key operational and technological areas are identified, conclusions and recommendations are made for further research, and an example developmental program leading to an operational telepresence servicer is presented

    Space Applications of Automation, Robotics and Machine Intelligence Systems (ARAMIS), phase 2. Volume 2: Telepresence project applications

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    The field of telepresence is defined and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA' plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies over the next decade are included

    Study in optimization of microcircuit design Final report

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    Optimization of microcircuit reliabilit

    Understanding Link Dynamics in Wireless Sensor Networks with Dynamically Steerable Directional Antennas

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    Abstract. By radiating the power in the direction of choice, electronicallyswitched directional (ESD) antennas can reduce network contention and avoid packet loss. There exists some ESD antennas for wireless sensor networks, but so far researchers have mainly evaluated their directionality. There are no studies regarding the link dynamics of ESD antennas, in particular not for indoor deployments and other scenarios where nodes are not necessarily in line of sight. Our long-term experiments confirm that previous findings that have demonstrated the dependence of angleof-arrival on channel frequency also hold for directional transmissions with ESD antennas. This is important for the design of protocols for wireless sensor networks with ESD antennas: the best antenna direction, i.e., the direction that leads to the highest packet reception rate and signal strength at the receiver, is not stable but varies over time and with the selected IEEE 802.15.4 channel. As this requires protocols to incorporate some form of adaptation, we present an intentionally simple and yet efficient mechanism for selecting the best antenna direction at run-time with an energy overhead below 2 % compared to standard omni-directional transmissions.

    Unveiling Photodeactivation Pathways for a New Iridium(III) Cyclometalated Complex

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    We report the synthesis and characterization of a neutral heteroleptic IrIII complex bearing 6-fluoro-2-phenylbenzo[d]thiazole as cyclometalating ligand and (Z)-6-(9H-carbazol-9-yl)-5-hydroxy-2,2-dimethylhex-4-en-3-one as ancillary ligand. The photodeactivation mechanisms have been elucidated through extensive density functional theory (DFT) calculations. The active role of metal-centered (3MC) triplet excited states in the nonradiative deactivation pathways is, for first time, confirmed in such complexes

    Budd-Chiari syndrome recurring in a transplanted liver

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    A patient with Budd-Chiari syndrome who underwent orthotopic liver transplantation and developed recurrent disease is described. The immediate postoperative period was complicated by multiple thrombotic episodes, followed by a period of apparent remission associated with the initiation of coumadin and persantine therapy. After discontinuation of such antithrombotic therapy in order to biopsy the liver, the patient experienced another series of clinically overt vascular thromboses and ultimately died of sepsis 15 mo posttransplantation after a prolonged and complicated terminal hospital course. At autopsy, recurrent Budd-Chiari syndrome as well as thromboses in numerous other organs was demonstrated. © 1983

    Incidence of Arrhythmias and Myocardial Ischaemia During Haemodialysis and Haemofiltration

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    Thirty-two patients (10 male, 22 female; age 37-82 years) undergoing maintenance haemodialysis or haemofiltration were studied by means of Holter device capable of simultaneously analysing rhythm and ST changes in three leads. Twenty-five patients were on haemodialysis, seven on haemofiltration, mean duration of haemodialysis/haemofiltration being 3.4±3 years. Incidence of ventricular tachycardia was low, being detected only in 1 of 32 patients. Ventricular premature beats in excess of 10/h during a period of 2 h were found in 8 of 32 patients and 100 supraventricular premature beats for 2 h or more in 4 of 32 patients. Both ventricular premature beats and supraventricular premature beats were most frequently recorded during the last hour of haemodialysis/haemofiltration. ECG signs of ischaemia were detected in eight patients, four of whom were asymptomatic. Ischaemia also occurred predominantly during the last hour of haemodialysis/haemofiltration. Two symptomatic patients displayed neither arrhythmias nor ST-changes while being monitored. The study shows that silent ischaemia and arrhythmias in patients under going chronic haemodialysis/haemofiltration may not be infrequent. Recognition of these events could be of importance in the management of these patient

    The effect of different types of hepatic injury on the estrogen and androgen receptor activity of liver

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    Mammalian liver contains receptors for both estrogens and androgens. Hepatic regeneration after partial hepatectomy in male rats is associated with a loss of certain male-specific hepatic characteristics. In this study we investigated the effects of lesser forms of hepatic injury on the levels of estrogen and androgen receptor activity in the liver. Adult male rats were subjected to portacaval shunt, partial portal vein ligation, hepatic artery ligation, or two-thirds partial hepatectomy. Another group of animals was treated with cyclosporine. At the time of sacrifice the livers were removed and used to determine the estrogen and androgen receptor activity in the hepatic cytosol. A significant reduction (p < 0.05) in the hepatic cytosolic androgen receptor activity and a slight increase in the estrogen receptor activity occurred following total portosystemic shunting. Partial ligation of the portal vein, which produces a lesser degree of portosystemic shunting, had no effect on the levels of the estrogen and androgen receptor activity present within hepatic cytosol. Cyclosporine-treated animals had significantly greater (p < 0.01) levels of estrogen receptor activity in the hepatic cytosol compared to vehicle-treated control animals. Levels of estrogen and androgen receptor activity within the hepatic cytosol remained unchanged after ligation of the hepatic artery. The reduction in the cytosolic estrogen and androgen receptor activity in the liver after partial hepatectomy was confirmed. In summary, certain types of hepatic injury are associated with profound changes in the estrogen and androgen receptor content within the liver. © 1989 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
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