891 research outputs found
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Characterisation of extraterrestrial samples by Raman and Electron microprobes
Casimir effect in 2+1 dimensional noncommutative theories
We study the Dirichlet Casimir effect for a complex scalar field on two
noncommutative spatial coordinates plus a commutative time. To that end, we
introduce Dirichlet-like boundary conditions on a curve contained in the
spatial plane, in such a way that the correct commutative limit can be reached.
We evaluate the resulting Casimir energy for two different curves: (a) Two
parallel lines separated by a distance , and (b) a circle of radius . In
the first case, the resulting Casimir energy agrees exactly with the one
corresponding to the commutative case, regardless of the values of and of
the noncommutativity scale , while for the latter the commutative
behaviour is only recovered when . Outside of that regime,
the dependence of the energy with is substantially changed due to
noncommutative corrections, becoming regular for .Comment: 12 pages, 3 figure
Representation of the Lagrange reconstructing polynomial by combination of substencils
The Lagrange reconstructing polynomial [Shu C.W.: {\em SIAM Rev.} {\bf 51}
(2009) 82--126] of a function on a given set of equidistant (\Delta
x=\const) points
is defined [Gerolymos G.A.: {\em J. Approx. Theory} {\bf 163} (2011) 267--305]
as the polynomial whose sliding (with ) averages on are equal to the Lagrange interpolating polynomial
of on the same stencil. We first study the fundamental functions of
Lagrange reconstruction, show that these polynomials have only real and
distinct roots, which are never located at the cell-interfaces (half-points)
(), and obtain several identities.
Using these identities, by analogy to the recursive Neville-Aitken-like
algorithm applied to the Lagrange interpolating polynomial, we show that there
exists a unique representation of the Lagrange reconstructing polynomial on
as a combination of the Lagrange reconstructing
polynomials on the substencils
(), with weights
which are rational
functions of () [Liu Y.Y., Shu C.W., Zhang M.P.: {\em
Acta Math. Appl. Sinica} {\bf 25} (2009) 503--538], and give an analytical
recursive expression of the weight-functions. We then use the analytical
expression of the weight-functions
to obtain a formal proof
of convexity (positivity of the weight-functions) in the neighborhood of
, under the condition that all of the substencils contain
either point or point (or both).Comment: final corrected version; in print J. Comp. Appl. Mat
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Laboratory capture, isolation and analysis of microparticles in aerogel: Preparation for the return of Stardust
We present observations from the laboratory capture of particles in aerogel. The paper focuses on a possible extraction technique and the bulk mineral characterization of the captured material using non-destructive analytical techniques
A novel HIV vaccine adjuvanted by IC31 induces robust and persistent humoral and cellular immunity.
The HIV vaccine strategy that, to date, generated immune protection consisted of a prime-boost regimen using a canarypox vector and an HIV envelope protein with alum, as shown in the RV144 trial. Since the efficacy was weak, and previous HIV vaccine trials designed to generate antibody responses failed, we hypothesized that generation of T cell responses would result in improved protection. Thus, we tested the immunogenicity of a similar envelope-based vaccine using a mouse model, with two modifications: a clade C CN54gp140 HIV envelope protein was adjuvanted by the TLR9 agonist IC31®, and the viral vector was the vaccinia strain NYVAC-CN54 expressing HIV envelope gp120. The use of IC31® facilitated immunoglobulin isotype switching, leading to the production of Env-specific IgG2a, as compared to protein with alum alone. Boosting with NYVAC-CN54 resulted in the generation of more robust Th1 T cell responses. Moreover, gp140 prime with IC31® and alum followed by NYVAC-CN54 boost resulted in the formation and persistence of central and effector memory populations in the spleen and an effector memory population in the gut. Our data suggest that this regimen is promising and could improve the protection rate by eliciting strong and long-lasting humoral and cellular immune responses
Approximation error of the Lagrange reconstructing polynomial
The reconstruction approach [Shu C.W.: {\em SIAM Rev.} {\bf 51} (2009)
82--126] for the numerical approximation of is based on the
construction of a dual function whose sliding averages over the interval
are equal to (assuming
an homogeneous grid of cell-size ). We study the deconvolution
problem [Harten A., Engquist B., Osher S., Chakravarthy S.R.: {\em J. Comp.
Phys.} {\bf 71} (1987) 231--303] which relates the Taylor polynomials of
and , and obtain its explicit solution, by introducing rational numbers
defined by a recurrence relation, or determined by their generating
function, , related with the reconstruction pair of . We
then apply these results to the specific case of Lagrange-interpolation-based
polynomial reconstruction, and determine explicitly the approximation error of
the Lagrange reconstructing polynomial (whose sliding averages are equal to the
Lagrange interpolating polynomial) on an arbitrary stencil defined on a
homogeneous grid.Comment: 31 pages, 1 table; revised version to appear in J. Approx. Theor
Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares
The extreme ultraviolet portion of the solar spectrum contains a wealth of
diagnostic tools for probing the lower solar atmosphere in response to an
injection of energy, particularly during the impulsive phase of solar flares.
These include temperature and density sensitive line ratios, Doppler shifted
emission lines and nonthermal broadening, abundance measurements, differential
emission measure profiles, and continuum temperatures and energetics, among
others. In this paper I shall review some of the advances made in recent years
using these techniques, focusing primarily on studies that have utilized data
from Hinode/EIS and SDO/EVE, while also providing some historical background
and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the
Topical Issue on Solar and Stellar Flare
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Microcraters in aluminum foils exposed by Stardust
We will present preliminary results on the nature and size frequency distribution of microcraters that formed in aluminum foils during the flyby of comet Wild 2 by the Stardust spacecraft
Clinical utility of vinblastine therapeutic drug monitoring for the treatment of infantile myofibroma patients:A case series
Infantile myofibroma is a rare, benign tumour of infancy typically managed surgically. In a minority of cases, more aggressive disease is seen and chemotherapy with vinblastine and methotrexate may be used, although evidence for this is limited. Chemotherapy dosing in infants is challenging, and vinblastine disposition in infants is unknown. We describe the use of vinblastine therapeutic drug monitoring in four cases of infantile myofibroma. Marked inter- and intrapatient variability was observed, highlighting the poorly understood pharmacokinetics of vinblastine in children, the challenges inherent in treating neonates, and the role of adaptive dosing in optimising drug exposure in challenging situations.</p
The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory
The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by
four institutions in Spain that flew on board the Sunrise balloon-borne
telesocope in June 2009 for almost six days over the Arctic Circle. As a
polarimeter IMaX uses fast polarization modulation (based on the use of two
liquid crystal retarders), real-time image accumulation, and dual beam
polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the
instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to
achieve a spectral resolution of 85 mAA. IMaX uses the high Zeeman sensitive
line of Fe I at 5250.2 AA and observes all four Stokes parameters at various
points inside the spectral line. This allows vector magnetograms, Dopplergrams,
and intensity frames to be produced that, after reconstruction, reach spatial
resolutions in the 0.15-0.18 arcsec range over a 50x50 arcsec FOV. Time
cadences vary between ten and 33 seconds, although the shortest one only
includes longitudinal polarimetry. The spectral line is sampled in various ways
depending on the applied observing mode, from just two points inside the line
to 11 of them. All observing modes include one extra wavelength point in the
nearby continuum. Gauss equivalent sensitivities are four Gauss for
longitudinal fields and 80 Gauss for transverse fields per wavelength sample.
The LOS velocities are estimated with statistical errors of the order of 5-40
m/s. The design, calibration and integration phases of the instrument, together
with the implemented data reduction scheme are described in some detail.Comment: 17 figure
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