1,234 research outputs found
Projection distortion analysis for flattened image mosaicing from straight uniform generalized cylinders
This paper presents a new approach for reconstructing images mapped or painted on straight uniform generalized cylinders (SUGC). A set of monocular images is taken from different viewpoints in order to be mosaiced and to represent the entire scene in detail. The expressions of the SUGC's projection axis are derived from two cross-sections projected onto the image plane. Based on these axes we derive the SUGC localization in the camera coordinate system. We explain how we can find a virtual image representation when the intersection of the two axes is matched to the image center. We analyze the perspective distortions when flattening a scene which is mapped on a SUGC. We evaluate the lower and the upper bounds of the necessary number of views in order to represent the entire scene from a SUGC, by considering the distortions produced by perspective projection. A region matching based mosaicing method is proposed to be applied on the flattened images in order to obtain the complete scene. The mosaiced scene is visualized on a new synthetic surface by a mapping procedure. The proposed algorithm is used for the representation of mural paintings located on SUGCs with closed cross-sections (circles for columns), or opened cross-sections (ellipses or parabolas for vaults). (C) 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved
Extraction of ellagitannins from oak wood of model casks
Eight experimental model casks were constructed using wood from four oak trees and filled with a 12 % ethanol solution for 200 days. The concentration of ellagitannins was subsequently measured in the solutions and in the inner and outer faces of the cask wood. Only a low proportion of the total ellagitannins was extracted from the wood, and this proportion varied significantly between both different casks and between the eight ellagitannins measured. The two most abundant ellagitannins, castalagin and vescalagin, were the least easily extracted. The concentration of ellagitannins was much lower in the solutions than expected from calculations based on the difference between the inner and outer faces of the wood. This degradation of ellagitannins occurs subsequent to their extraction into solution
Coupling MOAO with Integral Field Spectroscopy: specifications for the VLT and the E-ELT
[Abridged] We have developed an end-to-end simulation to specify the science
requirements of a MOAO-fed integral field spectrograph on either an 8m or 42m
telescope. Our simulations re-scales observations of local galaxies or results
from numerical simulations of disk or interacting galaxies. For the current
analysis, we limit ourselves to a local disk galaxy which exhibits simple
rotation and a simulation of a merger. We have attempted to generalize our
results by introducing the simple concepts of "PSF contrast" which is the
amount of light polluting adjacent spectra which we find drives the smallest EE
at a given spatial scale. The choice of the spatial sampling is driven by the
"scale-coupling", i.e., the relationship between the IFU pixel scale and the
size of the features that need to be recovered by 3D spectroscopy in order to
understand the nature of the galaxy and its substructure. Because the dynamical
nature of galaxies are mostly reflected in their large-scale motions, a
relatively coarse spatial resolution is enough to distinguish between a
rotating disk and a major merger. Although we used a limited number of
morpho-kinematic cases, our simulations suggest that, on a 42m telescope, the
choice of an IFU pixel scale of 50-75 mas seems to be sufficient. Such a coarse
sampling has the benefit of lowering the exposure time to reach a specific
signal-to-noise as well as relaxing the performance of the MOAO system. On the
other hand, recovering the full 2D-kinematics of z~4 galaxies requires high
signal-to-noise and at least an EE of 34% in 150 mas (2 pixels of 75 mas).
Finally, we carried out a similar study at z=1.6 with a MOAO-fed spectrograph
for an 8m, and find that at least an EE of 30% at 0.25 arcsec spatial sampling
is required to understand the nature of disks and mergers.Comment: 17 pages, 20 figures, accepted for publication in the MNRA
Electron emission at very low electron impact energy: experimental and Monte-Carlo results
The behaviour of electron emission under electron impact at very low energy
is of great importance in many applications such as high energy physics,
satellites, nuclear reactors, etc. However the question of the total electron
reflectivity is still in discussion. Our experimental and theoretical studies
show that the total reflectivity at very low energy is far from being an
obvious fact. Moreover, our results show that the yield is close to zero and
not equal to one for low energy incident electron.Comment: 3 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop
on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba,
Italy; CERN Yellow Report CERN-2013-002, pp.137-13
Raman G and D band in strongly photoexcited carbon nanotubes
We observe clear differences in the spectral shift of the Raman D and G bands when heating double wall carbon nanotubes through intense photon irradiation and by varying the temperature in a thermostat. These spectral differences are attributed to modifications of the defect induced double-resonance Raman process, and are consistent with Stokes–anti-Stokes anomalies observed for single and double wall carbon nanotubes, not present in graphite. We find that the Raman intensity for double wall carbon nanotubes increases superlinearly in the red spectral region and sublinearly in the UV spectral region
Raman G band in double-wall carbon nanotubes combining p doping and high pressure
We use sulfuric acid as pressure medium to extrapolate the G-band position of the inner and outer tubes of double-wall carbon nanotubes. Keeping the G-band position of the inner and outer tubes constant, we can determine the fraction of double-wall and single-wall tubes in samples containing a mixture of the two. A-band-related electronic interwall interaction at 1560 cm−1 is observed, which is associated with the outer tube walls. This band is observed to shift with pressure at the same rate as the G band of outer tubes and is not suppressed with chemical doping. Differences in the interwall interaction is discussed for double-wall carbon nanotubes grown by the catalytic chemical-vapor method and double-wall carbon nanotubes obtained through
transformation of peapods
Update on the ICUD-SIU consultation on multi-parametric magnetic resonance imaging in localised prostate cancer
Introduction: Prostate cancer (PCa) imaging is a rapidly evolving field. Dramatic improvements in prostate MRI during the last decade will probably change the accuracy of diagnosis. This chapter reviews recent current evidence about MRI diagnostic performance and impact on PCa management. Materials and methods: The International Consultation on Urological Diseases nominated a committee to review the literature on prostate MRI. A search of the PubMed database was conducted to identify articles focussed on MP-MRI detection and staging protocols, reporting and scoring systems, the role of MP-MRI in diagnosing PCa prior to biopsy, in active surveillance, in focal therapy and in detecting local recurrence after treatment. Results: Differences in opinion were reported in the use of the strength of magnets [1.5 Tesla (T) vs. 3T] and coils. More agreement was found regarding the choice of pulse sequences; diffusion-weighted MRI (DW-MRI), dynamic contrast-enhanced MRI (DCE MRI), and/or MR spectroscopy imaging (MRSI) are recommended in addition to conventional T2-weighted anatomical sequences. In 2015, the Prostate Imaging Reporting and Data System (PI-RADS version 2) was described to standardize image acquisition and interpretation. MP-MRI improves detection of clinically significant PCa (csPCa) in the repeat biopsy setting or before the confirmatory biopsy in patients considering active surveillance. It is useful to guide focal treatment and to detect local recurrences after treatment. Its role in biopsy-naive patients or during the course of active surveillance remains debated. Conclusion: MP-MRI is increasingly used to improve detection of csPCa and for the selection of a suitable therapeutic approach
Remote sensing techniques in the mapping of vegetation and their application to runoff evolution in burnt areas
South of experimental forested catchments named "Réal Collo- brier" was destroyed by fire in August 1990. Partially or entirely bumt catchments became an interesting field to study links between vegetation and runoff. An experimental program was built on two axis : - use of remote sensing techniques to map limits of bumt areas and recovery of vegetation, year after year.- link between vegetation and runoff. The first investigations were done on two bumt catchments (Rimbaud and Meffrey), using a runoff model fitted with data before fire. This model has permitted to compare new data (observed after fire) with the ones we would have observed without fire, for the months just after fire (1990, direct effect of fire) and the year after (1991, effect of vegetation recovery
Quality Assessment of Oenological Tannins Utilising Global Selectivity Chemical Sensors Array (“Electronic Tongue”)
Oenological tannin is a common name for food additives containing tannins utilised in winemaking practices. The maintaste feature of oenological tannin is the taste sensation of astringency and bitterness. In the present paper, samples ofvarious oenological tannins (oak, chestnut, gall, tara, querbacho, grape seed and grape skin tannins) were analysed bymeans of a tasting panel, measuring the flavour attributes bitterness, astringency, body, duration of flavour and similaritywith wine tannins, and using the array of global selectivity chemical sensors (electronic tongue) “α-ASTREE” Liquid andTaste Analyzer (Alpha M.O.S., Toulouse, France). Principal component analysis of the electronic tongue outputs appliedfor different tannin solutions provides good discrimination according to their chemical nature. Consequently, three mainclasses of oenological tannins, namely gallotannins, ellagitannins and condensed tannins, could be identified and separated.The global output of the electronic tongue is quite responsive to changes in the bitterness and astringency of model quinineand alum solutions and, once calibrated (correlation coefficients of 0.976 (p<0.001) and 0.996 (p<0.001) respectively) couldquantify their concentrations with good precision. The electronic tongue output was found to be correlated with the flavourattributes of oenological tannins. The best correlation was observed for bitterness. This fact could be explained by moreconstant calibration and lesser influence of any interfering factors on this attribute
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