261 research outputs found
Deexcitation nuclear gamma-ray line emission from low-energy cosmic rays in the inner Galaxy
Recent observations of high ionization rates of molecular hydrogen in diffuse
interstellar clouds point to a distinct low-energy cosmic-ray component.
Supposing that this component is made of nuclei, two models for the origin of
such particles are explored and low-energy cosmic-ray spectra are calculated
which, added to the standard cosmic ray spectra, produce the observed
ionization rates. The clearest evidence of the presence of such low-energy
nuclei between a few MeV per nucleon and several hundred MeV per nucleon in the
interstellar medium would be a detection of nuclear \gamma-ray line emission in
the range E_ 0.1 - 10 MeV, which is strongly produced in their collisions with
the interstellar gas and dust. Using a recent \gamma-ray cross section
compilation for nuclear collisions, \gamma-ray line emission spectra are
calculated alongside with the high-energy \gamma-ray emission due to {\pi} 0
decay, the latter providing normalization of the absolute fluxes by comparison
with Fermi-LAT observations of the diffuse emission above E \gamma = 0.1 GeV.
Our predicted fluxes of strong nuclear \gamma-ray lines from the inner Galaxy
are well below the detection sensitivies of INTEGRAL, but a detection,
especially of the 4.4-MeV line, seems possible with new-generation \gamma-ray
telescopes based on available technology. We predict also strong \gamma-ray
continuum emission in the 1-8 MeV range, which in a large part of our model
space for low-energy cosmic rays exceeds considerably estimated instrument
sensitivities of future telescopes.Comment: 22 pages, 7 figures, accepted for publication in ApJ; figures 6 and 7
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Spectral Domain Approach Of Multilayered Superconducting Microstrip Line Using a New Set of Edge-Conditioned Basis Functions
A new set of edge-conditioned basis functions is used to determine the dispersion properties of microstrip line. Since An alternative formulation of the spectral domain approach (SDA) method presented for high-temperature superconducting microstrip line Green’s function derivation. The method relies on reflection factor rather than the transverse impedance used in the immittance approach. The inner products is involved in the Galerkin procedure are pole-free. The numerical examples are presented and close agreement is obtained between simulated and published data.A new set of edge-conditioned basis functions is used to determine the dispersion properties of microstrip line. Since An alternative formulation of the spectral domain approach (SDA) method presented for high-temperature superconducting microstrip line Green’s function derivation. The method relies on reflection factor rather than the transverse impedance used in the immittance approach. The inner products is involved in the Galerkin procedure are pole-free. The numerical examples are presented and close agreement is obtained between simulated and published data
Multidisciplinary consulting in neuro-orthopedic pathology: An experience in central hospital of Constantine
SuperpixelGridCut, SuperpixelGridMean and SuperpixelGridMix Data Augmentation
A novel approach of data augmentation based on irregular superpixel
decomposition is proposed. This approach called SuperpixelGridMasks permits to
extend original image datasets that are required by training stages of machine
learning-related analysis architectures towards increasing their performances.
Three variants named SuperpixelGridCut, SuperpixelGridMean and
SuperpixelGridMix are presented. These grid-based methods produce a new style
of image transformations using the dropping and fusing of information.
Extensive experiments using various image classification models and datasets
show that baseline performances can be significantly outperformed using our
methods. The comparative study also shows that our methods can overpass the
performances of other data augmentations. Experimental results obtained over
image recognition datasets of varied natures show the efficiency of these new
methods. SuperpixelGridCut, SuperpixelGridMean and SuperpixelGridMix codes are
publicly available at https://github.com/hammoudiproject/SuperpixelGridMasksComment: The project is available at
https://github.com/hammoudiproject/SuperpixelGridMask
A vision transformer-based framework for knowledge transfer from multi-modal to mono-modal lymphoma subtyping models
Determining lymphoma subtypes is a crucial step for better patients treatment
targeting to potentially increase their survival chances. In this context, the
existing gold standard diagnosis method, which is based on gene expression
technology, is highly expensive and time-consuming making difficult its
accessibility. Although alternative diagnosis methods based on IHC
(immunohistochemistry) technologies exist (recommended by the WHO), they still
suffer from similar limitations and are less accurate. WSI (Whole Slide Image)
analysis by deep learning models showed promising new directions for cancer
diagnosis that would be cheaper and faster than existing alternative methods.
In this work, we propose a vision transformer-based framework for
distinguishing DLBCL (Diffuse Large B-Cell Lymphoma) cancer subtypes from
high-resolution WSIs. To this end, we propose a multi-modal architecture to
train a classifier model from various WSI modalities. We then exploit this
model through a knowledge distillation mechanism for efficiently driving the
learning of a mono-modal classifier. Our experimental study conducted on a
dataset of 157 patients shows the promising performance of our mono-modal
classification model, outperforming six recent methods from the
state-of-the-art dedicated for cancer classification. Moreover, the power-law
curve, estimated on our experimental data, shows that our classification model
requires a reasonable number of additional patients for its training to
potentially reach identical diagnosis accuracy as IHC technologies
Learning Boundary Edges for 3D-Mesh Segmentation
International audienceThis paper presents a 3D-mesh segmentation algorithm based on a learning approach. A large database of manually segmented 3D-meshes is used to learn a boundary edge function. The function is learned using a classifier which automatically selects from a pool of geometric features the most relevant ones to detect candidate boundary edges. We propose a processing pipeline that produces smooth closed boundaries using this edge function. This pipeline successively selects a set of candidate boundary contours, closes them and optimizes them using a snake movement. Our algorithm was evaluated quantitatively using two different segmentation benchmarks and was shown to outperform most recent algorithms from the state-of-the-art
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Intensifying chitin hydrolysis by adjunct treatments – an overview
Chitin is, after cellulose, the most abundant organic natural polysaccharide on Earth, being synthesized as a dominant component in the exoskeletons of crustaceans, among other sources. In the processing of seafood for human consumption, between 40 and 50% of the total raw material mass is wasted, causing a significant problem for the environment due to its slow degradation. Efforts to find uses for chitin derivatives, particularly their oligomers, have intensified since these chemicals are highly functional and offer a wide range of applications, especially as antimicrobial agent. As a consequence, some adjunct treatments, either chemical or physical in nature, have been employed to assist acid and enzymatic hydrolysis. This work provides a detailed review of the methods employed to intensify the formation of chitin oligomers, particularly focusing on the adjunct treatments used (microwave, ultrasonication, steam explosion and gamma irradiation), and evaluate the yield and characteristics of the oligomers formed. Adjunct treatments are more suitable for enzymatic hydrolysis since these treatments modify the chitin structure, and enhance the hydrolysis rate and yield of the oligomers, under milder reaction conditions. For future research, it would be worth trying pre-treatments like the application of high-pressure to chitin in order to lower its crystallinity
Analyse et gestion de l’occupation de places de stationnement par vision artificielle
Cet article présente un système de surveillance basé sur la vision pour le développement de services de gestion de places de parking. Le système présenté est un système adaptable pour l'analyse de places de stationnement dans des parkings de différentes configurations. Dans ce but, des expérimentations ont été menées sous différentes prises de vue en utilisant une caméra connectée à une station de travail mobile. Les résultats obtenus montrent la faisabilité du système dans l'analyse et dans la gestion des emplacements de parking avec des véhicules
Gamma ray production cross sections in proton induced reactions on natural Mg, Si and Fe targets over the proton energy range 30 up to 66 MeV
Gamma-ray excitation functions have been measured for 30, 42, 54 and 66 MeV
proton beams accelerated onto C + O (Mylar), Mg, Si, and Fe targets of
astrophysical interest at the separate-sector cyclotron of iThemba LABS in
Somerset West (Cape Town, South Africa). A large solid angle, high energy
resolution detection system of the Eurogam type was used to record Gamma-ray
energy spectra. Derived preliminary results of Gamma-ray line production cross
sections for the Mg, Si and Fe target nuclei are reported and discussed. The
current cross section data for known, intense Gamma-ray lines from these nuclei
consistently extend to higher proton energies previous experimental data
measured up to Ep ~ 25 MeV at the Orsay and Washington tandem accelerators.
Data for new Gamma-ray lines observed for the first time in this work are also
reported.Comment: 11 pages, 6 figures. IOP Institute of Physics Conference Nuclear
Physics in Astrophysics VII, 28th EPF Nuclear Physics Divisional Conference,
May 18-22 2015, York, U
Novel Correlations between Spectroscopic and Morphological Properties of Activated Carbons from Waste Coffee Grounds
Massive quantities of spent coffee grounds (SCGs) are generated by users around the world.
Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM, 13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data
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