5,798 research outputs found

    Management system requirements for wireless systems beyond 3G

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    This paper presents a comprehensive description of various management system requirements for systems beyond 3G, which have been identified as a result of the Software Based Systems activities within the Mobile VCE Core 2 program. Specific requirements for systems beyond 3G are discussed and potential technologies to address them proposed. The analysis has been carried out from network, service and security viewpoints

    Aggregates of two-dimensional vesicles: Rouleaux and sheets

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    Using both numerical and variational minimization of the bending and adhesion energy of two-dimensional lipid vesicles, we study their aggregation, and we find that the stable aggregates include an infinite number of vesicles and that they arrange either in a columnar or in a sheet-like structure. We calculate the stability diagram and we discuss the modes of transformation between the two types of aggregates, showing that they include disintegration as well as intercalation.Comment: 4 figure

    Exobiology in Earth orbit: The results of science workshops held at NASA, Ames Research Center

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    The Workshops on Exobiology in Earth Orbit were held to explore concepts for orbital experiments of exobiological interest and make recommendations on which classes of experiments should be carried out. Various observational and experimental opportunities in Earth orbit are described including those associated with the Space Shuttle laboratories, spacecraft deployed from the Space Shuttle and expendable launch vehicles, the Space Station, and lunar bases. Specific science issues and technology needs are summarized. Finally, a list of recommended experiments in the areas of observational exobiology, cosmic dust collection, and in situ experiments is presented

    Mediatization of Emotion on Social Media: Forms and Norms in Digital Mourning Practices

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    This article provides the theoretical background for this Special Issue which explores the mediatization of emotion on social media as attested in different digital mourning practices. The overview discusses the affective and emotional turn alongside the mediatic turn in relation to key trends and foci in the study of affect/emotion. Our discussion points to a shift in conceptualizations of affect/emotion from mediated to mediatized practice, embedded in other social practices and subject to media and social media logics, affordances, and frames, which are worthy of empirical investigation. The article also presents key insights offered in the four articles of this Special Issue and foregrounds current and future directions in the study of mediatization, emotional sharing, and digital mourning practices

    Voltage-controlled electron tunnelling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell

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    We perform high-resolution photocurrent (PC) spectroscopy to investigate resonantly the neutral exciton ground-state (X0) in a single InAs/GaAs self-assembled quantum dot (QD) embedded in the intrinsic region of an n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which was formed from a Si delta-doped GaAs layer. Using such a device, a single-QD PC spectrum of X0 is measured by sweeping the bias-dependent X0 transition energy through that of a fixed narrow-bandwidth laser via the quantum-confined Stark effect (QCSE). By repeating such a measurement for a series of laser energies, a precise relationship between the X0 transition energy and bias voltage is then obtained. Taking into account power broadening of the X0 absorption peak, this allows for high-resolution measurements of the X0 homogeneous linewidth and, hence, the electron tunnelling rate. The electron tunnelling rate is measured as a function of the vertical electric field and described accurately by a theoretical model, yielding information about the electron confinement energy and QD height. We demonstrate that our devices can operate as 2DEG-based QD photovoltaic cells and conclude by proposing two optical spintronic devices that are now feasible.Comment: 34 pages, 11 figure

    Non-linear photonic crystals as a source of entangled photons

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    Non-linear photonic crystals can be used to provide phase-matching for frequency conversion in optically isotropic materials. The phase-matching mechanism proposed here is a combination of form birefringence and phase velocity dispersion in a periodic structure. Since the phase-matching relies on the geometry of the photonic crystal, it becomes possible to use highly non-linear materials. This is illustrated considering a one-dimensional periodic Al0.4_{0.4}Ga0.6_{0.6}As / air structure for the generation of 1.5 ÎĽ\mum light. We show that phase-matching conditions used in schemes to create entangled photon pairs can be achieved in photonic crystals.Comment: 4 pages, 3 figure

    Endoscopic ultrasound sedation in the United Kingdom: Is life without propofol tolerable?

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    There is compelling evidence to support the quality, cost effectiveness and safety profile of non-anesthesiologist-administered propofol for endoscopic ultrasound (EUS). However in the United Kingdom, it is recommended that the administration and monitoring of propofol sedation for endoscopic procedures should be the responsibility of a dedicated and appropriately trained anaesthetist only. The majority of United Kingdom EUS procedures are performed with opiate and benzodiazepine sedation rather than anaesthetist led propofol lists due to anaesthetist resource availability. We sought to prospectively determine the tolerability and safety of EUS with benzodiazepine and opiate sedation in single United Kingdom centre. Two hundred consecutive patients undergoing either EUS or oesophago-gastroduodenoscopy (OGD) with conscious sedation were prospectively recruited with a 1:1 enrolment ratio. Patients completed questionnaires pre and post procedure detailing anticipated and actual pain experienced on a 1-10 visual analogue scale. Demographics, procedure duration, sedation doses and willingness to repeat the procedure were also recorded. EUS procedures lasted significantly longer than OGDs (15 min vs 6 min, P < 0.0001), however, there was no difference in anticipated pain scores between the groups (EUS 3.37/10 vs OGD 3.47/10, P = 0.46). Pain scores indicated EUS was better tolerated than OGD (1.16/10 vs 1.88/10, P = 0.03) although higher doses of sedation were used for EUS procedures. There were no complications identified in either group. We feel our study demonstrates that the tolerability of EUS with opiate and benzodiazepine sedation is acceptable

    Engineering New Approaches to Cancer Vaccines

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    available in PMC 2016 August 01Recently, a number of promising approaches have been developed using synthetic chemistry, materials science, and bioengineering-based strategies to address challenges in the design of more effective cancer vaccines. At the stage of initial priming, potency can be improved by maximizing vaccine delivery to lymph nodes. Because lymphatic uptake from peripheral tissues is strongly size dependent, antigens and adjuvants packaged into optimally sized nanoparticles access the lymph node with much greater efficiency than unformulated vaccines. Once primed, T cells must home to the tumor site. Because T cells acquire the necessary surface receptors in the local lymph node draining the tissue of interest, vaccines must be engineered that reach organs, such as the lung and gut, which are common sites of tumor lesions but inaccessible by traditional vaccination routes. Particulate vaccine carriers can improve antigen exposure in these organs, resulting in greater lymphocyte priming. Immunomodulatory agents can also be injected directly into the tumor site to stimulate a systemic response capable of clearing even distal lesions; materials have been designed that entrap or slowly release immunomodulators at the tumor site, reducing systemic exposure and improving therapeutic efficacy. Finally, lessons learned from the design of biomaterial-based scaffolds in regenerative medicine have led to the development of implantable vaccines that recruit and activate antigen-presenting cells to drive antitumor immunity. Overall, these engineering strategies represent an expanding toolkit to create safe and effective cancer vaccines.United States. National Institutes of Health (CA174795)United States. National Institutes of Health (CA172164

    Realisation of Hardy's Thought Experiment

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    We present an experimental realisation of Hardy's thought experiment [Phys. Rev. Lett. {\bf 68}, 2981 (1992)], using photons. The experiment consists of a pair of Mach-Zehnder interferometers that interact through photon bunching at a beam splitter. A striking contradiction is created between the predictions of quantum mechanics and local hidden variable based theories. The contradiction relies on non-maximally entangled position states of two particles.Comment: 5 page
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