5,605 research outputs found
Management system requirements for wireless systems beyond 3G
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
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
Mortality associated with avian reovirus infection in a free-living magpie (Pica pica) in Great Britain
Avian reoviruses (ARVs) cause a range of disease presentations in domestic, captive and free-living bird species. ARVs have been reported as a cause of significant disease and mortality in free-living corvid species in North America and continental Europe. Until this report, there have been no confirmed cases of ARV-associated disease in British wild birds
Mediatization of Emotion on Social Media: Forms and Norms in Digital Mourning Practices
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
Non-linear photonic crystals as a source of entangled photons
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 AlGaAs / air structure for the generation of 1.5
m 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?
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
Voltage-controlled electron tunnelling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell
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
- …