411 research outputs found
Results and questions on a nonlinear approximation approach for solving high-dimensional partial differential equations
We investigate mathematically a nonlinear approximation type approach
recently introduced in [A. Ammar et al., J. Non-Newtonian Fluid Mech., 2006] to
solve high dimensional partial differential equations. We show the link between
the approach and the greedy algorithms of approximation theory studied e.g. in
[R.A. DeVore and V.N. Temlyakov, Adv. Comput. Math., 1996]. On the prototypical
case of the Poisson equation, we show that a variational version of the
approach, based on minimization of energies, converges. On the other hand, we
show various theoretical and numerical difficulties arising with the non
variational version of the approach, consisting of simply solving the first
order optimality equations of the problem. Several unsolved issues are
indicated in order to motivate further research
Pratiques résidentielles et impact sur les dynamiques et la segmentation de grandes métropoles : étude des formes de mobilité spatiale des populations de Bogota et de Delhi : rapport intermédiaire n°4
Measurement of the neutron electric dipole moment by crystal diffraction
An experiment using a prototype setup to search for the neutron electric
dipole moment by measuring spin-rotation in a non-centrosymmetric crystal
(quartz) was carried out to investigate statistical sensitivity and systematic
effects of the method. It has been demonstrated that the concept of the method
works. The preliminary result of the experiment is ecm. The experiment showed that an accuracy of ecm can be obtained in 100 days data taking, using available
quartz crystals and neutron beams.Comment: 13 pages, 4 figure
About the origin of low wafer performance and crystal defect generation on seed-cast growth of industrial mono-like silicon ingots
The era of the seed-cast grown monocrystalline-based silicon ingots is coming. Mono-like, pseudomono or quasimono wafers are product labels that can be nowadays found in the market, as a critical innovation for the photovoltaic industry. They integrate some of the most favorable features of the conventional silicon substrates for solar cells, so far, such as the high solar cell efficiency offered by the monocrystalline Czochralski-Si (Cz-Si) wafers and the lower cost, high productivity and full square-shape that characterize the well-known multicrystalline casting growth method. Nevertheless, this innovative crystal growth approach still faces a number of mass scale problems that need to be resolved, in order to gain a deep, 100% reliable and worldwide market: (i) extended defects formation during the growth process; (ii) optimization of the seed recycling; and (iii) parts of the ingots giving low solar cells performance, which directly affect the production costs and yield of this approach. Therefore, this paper presents a series of casting crystal growth experiments and characterization studies from ingots, wafers and cells manufactured in an industrial approach, showing the main sources of crystal defect formation, impurity enrichment and potential consequences at solar cell level. The previously mentioned technological drawbacks are directly addressed, proposing industrial actions to pave the way of this new wafer technology to high efficiency solar cells
IL-7 abrogates memory T regulatory cell functions by modulation of CD39/ATP axis in vitro and in vivo in HIV infected and non-infected patients
Discovery of a faint optical jet in 3C 120
We report the detection of an optical jet in the nearby Seyfert 1 radio
galaxy 3C 120. The optical jet coincides with the well-known radio jet and
emits continuum radiation (B,V',I) with a radio-to-optical spectral index of
0.65. There are no clear optical counterparts to the radio knots, although the
optical condensation A of the galaxy, which includes the bright 4" radio knot,
is found to be 12 % polarized with the electric field vectors perpendicular to
the jet. These findings indicate that 3C 120 contains the 6th known
extragalactic optical synchrotron jet, quite similar in its properties to the
jet of PKS 0521-36. The outer parts of the jet is the faintest known optical
jet and was discovered as the result of a dedicated effort to detect it. It is
therefore possible that more optical jets can be discovered in systematic
searches by combining deep imaging in the optical or near-IR with careful
galaxy subtraction methods
A study of general practitioners' perspectives on electronic medical records systems in NHS Scotland
<b>Background</b> Primary care doctors in NHSScotland have been using electronic medical records within their practices routinely for many years. The Scottish Health Executive eHealth strategy (2008-2011) has recently brought radical changes to the primary care computing landscape in Scotland: an information system (GPASS) which was provided free-of-charge by NHSScotland to a majority of GP practices has now been replaced by systems provided by two approved commercial providers. The transition to new electronic medical records had to be completed nationally across all health-boards by March 2012. <p></p><b>
Methods</b> We carried out 25 in-depth semi-structured interviews with primary care doctors to elucidate GPs' perspectives on their practice information systems and collect more general information on management processes in the patient surgical pathway in NHSScotland. We undertook a thematic analysis of interviewees' responses, using Normalisation Process Theory as the underpinning conceptual framework. <p></p>
<b>Results</b> The majority of GPs' interviewed considered that electronic medical records are an integral and essential element of their work during the consultation, playing a key role in facilitating integrated and continuity of care for patients and making clinical information more accessible. However, GPs expressed a number of reservations about various system functionalities - for example: in relation to usability, system navigation and information visualisation.
<b>Conclusion </b>Our study highlights that while electronic information systems are perceived as having important benefits, there remains substantial scope to improve GPs' interaction and overall satisfaction with these systems. Iterative user-centred improvements combined with additional training in the use of technology would promote an increased understanding, familiarity and command of the range of functionalities of electronic medical records among primary care doctors
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