7,356 research outputs found

    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 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), 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

    Operational determination of multi-qubit entanglement classes via tuning of local operations

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    We present a physical setup with which it is possible to produce arbitrary symmetric long-lived multiqubit entangled states in the internal ground levels of photon emitters, including the paradigmatic GHZ and W states. In the case of three emitters, where each tripartite entangled state belongs to one of two well-defined entanglement classes, we prove a one-to-one correspondence between well-defined sets of experimental parameters, i.e., locally tunable polarizer orientations, and multiqubit entanglement classes inside the symmetric subspace.Comment: Improved version. Accepted in Physical Review Letter

    Generation of Symmetric Dicke States of Remote Qubits with Linear Optics

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    We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states.Comment: New version, a few modifications and a new figure, accepted in Physical Review Letter

    Generation of Total Angular Momentum Eigenstates in Remote Qubits

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    We propose a scheme enabling the universal coupling of angular momentum of NN remote noninteracting qubits using linear optical tools only. Our system consists of NN single-photon emitters in a Λ\Lambda-configuration that are entangled among their long-lived ground-state qubits through suitably designed measurements of the emitted photons. In this manner, we present an experimentally feasible algorithm that is able to generate any of the 2N2^N symmetric and nonsymmetric total angular momentum eigenstates spanning the Hilbert space of the NN-qubit compound.Comment: 5 pages, 4 figures, improved presentation. Accepted in Physical Review

    Biomethane as alternative fuel for the EU road sector: analysis of existing and planned infrastructure

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    The views expressed here are purely those of the authors and may not, under any circumstances, be regarded as an official position of the European Commission

    A versatile source of polarization-entangled photons

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    We propose a method for the generation of a large variety of entangled states, encoded in the polarization degrees of freedom of N photons, within the same experimental setup. Starting with uncorrelated photons, emitted from N arbitrary single photon sources, and using linear optical tools only, we demonstrate the creation of all symmetric states, e.g., GHZ- and W-states, as well as all symmetric and non-symmetric total angular momentum eigenstates of the N qubit compound.Comment: 4 pages, 3 figure

    Liver Transplantation in Older Patients

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    To the Editor: The impact of liver transplantation on public health policy has not been delineated, partly because of uncertainty about the upper age limit for candidacy. We have compared the outlook in 363 adult recipients of livers who were less than 50 years old (mean +SD, 35.8+8.5) and 92 recipients who were 50 to 77 years old (mean +SD, 55.7+4.8). Cyclosporine and steroids1,2 were used for immunosuppression, and monoclonal antilymphocyte globulin3 and azathioprine were added as needed. The techniques of liver transplantation4 were not influenced by the age of the patient. The indications for transplantation are shown in Figure 1…., No extract is available for articles shorter than 400 words. © 1987, Massachusetts Medical Society. All rights reserved

    Sex Hormone-Related Functions in Regenerating Male Rat Liver

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    Sex hormone receptors were quantitated in normal male rat liver and in regenerating liver at several different times after partial (70%) hepatectomy. Both estrogen and androgen receptor content were altered dramatically by partial hepatectomy. Total hepatic content and nuclear retention of estrogen receptors increased, with the zenith evident 2 days after partial hepatectomy, corresponding to the zenith of mitotic index. Serum estradiol increased after 1 day, and reached a maximum at 3 days after surgery. In contrast, total and nuclear androgen receptor content demonstrated a massive decline at 1, 2, and 3 days after resection. Serum testosterone displayed a parallel decline. In addition, hepatic content of two androgen-responsive proteins was reduced to 15% and 13% of normal values during this period. The activity of these various proteins during regeneration of male rat liver is comparable to that observed in the liver of normal female rats. Taken together, these results indicate that partial hepatectomy induces a feminization of certain sexually dimorphic aspects of liver function in male rats. Furthermore, these data provide evidence that estrogens, but not androgens, may have an important role in the process of liver regeneration. © 1986, American Gastroenterological Association. All rights reserved
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