126 research outputs found
Absorption mechanisms in photon induced two-body knockout
Calculations have been performed for the O(,pn) and the
O(,pp) reaction in the photon-energy range = 60-300
MeV. Besides the contribution from the more common photoabsorption on the
pionic degrees of freedom, we have investigated the influence of heavier meson
exchange () and intermediate creation with
and exchange. Whereas the meson is found to set the main trends,
the meson is found not to be discardable in a theoretical description of
the (,pn) reaction. The incorporation of an energy dependence and a
decay width in the propagator is observed to be essential in order to
arrive at a more realistic description of (,NN) reactions at higher
photon energies.Comment: 10 pages, 5 figures in seperate postscript file, Submitted to Phys.
Lett. B. - INW9306I
Multimodal-based Diversified Summarization in Social Image Retrieval
In this paper, we describe our approach and its results for the MediaEval 2015 Retrieving Diverse Social Images task. The main strength of the proposed approach is its flexibility that permits to filter out irrelevant images, and to obtain a reli- able set of diverse and relevant images. This is done by first clustering similar images according to their textual descrip- tions and their visual content, and then extracting images from different clusters according to a measure of user’s cred- ibility. Experimental results shown that it is stable and has little fluctuation in both single-concept and multi-concept queries
Benchmarking van der Waals Density Functionals with Experimental Data: Potential Energy Curves for H2 Molecules on Cu(111), (100), and (110) Surfaces
Detailed physisorption data from experiment for the H_2 molecule on low-index
Cu surfaces challenge theory. Recently, density-functional theory (DFT) has
been developed to account for nonlocal correlation effects, including van der
Waals (dispersion) forces. We show that the functional vdW-DF2 gives a
potential-energy curve, potential-well energy levels, and difference in lateral
corrugation promisingly close to the results obtained by resonant elastic
backscattering-diffraction experiments. The backscattering barrier is found
selective for choice of exchange-functional approximation. Further, the DFT-D3
and TS-vdW corrections to traditional DFT formulations are also benchmarked,
and deviations are analyzed.Comment: 15 pages, 9 figure
Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei
The polarization degrees of freedom in photoinduced two-nucleon knockout from
finite nuclei are studied. It is pointed out that they open good perspectives
to study the dynamics of dinucleons in the medium in detail. The ()
and () angular cross sections, photon asymmetries and outgoing
nucleon polarizations are calculated for the target nuclei O and
C and photonenergies ranging from 100 up to 500 MeV. It is investigated
to which degree the two-nucleon emission reaction is dominated by
photoabsorption on proton-neutron and proton-proton
pairs in the nuclear medium. The calculations demonstrate that dominance of
wave photoabsorption in the () channel does not necessarily imply
that the reaction mechanism is similar to what is observed in deuteron
photodisintegration.Comment: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS forma
Overview of ImageCLEF 2017: Information extraction from images
This paper presents an overview of the ImageCLEF 2017 evaluation campaign, an event that was organized as part of the CLEF (Conference and Labs of the Evaluation Forum) labs 2017. ImageCLEF is an ongoing initiative (started in 2003) that promotes the evaluation of technologies for annotation, indexing and retrieval for providing information access to collections of images in various usage scenarios and domains. In 2017, the 15th edition of ImageCLEF, three main tasks were proposed and one pilot task: (1) a LifeLog task about searching in LifeLog data, so videos, images and other sources; (2) a caption prediction task that aims at predicting the caption of a figure from the biomedical literature based on the figure alone; (3) a tuberculosis task that aims at detecting the tuberculosis type from CT (Computed Tomography) volumes of the lung and also the drug resistance of the tuberculosis; and (4) a remote sensing pilot task that aims at predicting population density based on satellite images. The strong participation of over 150 research groups registering for the four tasks and 27 groups submitting results shows the interest in this benchmarking campaign despite the fact that all four tasks were new and had to create their own community
Weak Localization Effect in Superconductors by Radiation Damage
Large reductions of the superconducting transition temperature and
the accompanying loss of the thermal electrical resistivity (electron-phonon
interaction) due to radiation damage have been observed for several A15
compounds, Chevrel phase and Ternary superconductors, and in
the high fluence regime. We examine these behaviors based on the recent theory
of weak localization effect in superconductors. We find a good fitting to the
experimental data. In particular, weak localization correction to the
phonon-mediated interaction is derived from the density correlation function.
It is shown that weak localization has a strong influence on both the
phonon-mediated interaction and the electron-phonon interaction, which leads to
the universal correlation of and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information,
Plesse see http://www.fen.bilkent.edu.tr/~yjki
Dynamic control of proinflammatory cytokines Il-1β and Tnf-α by macrophages in zebrafish spinal cord regeneration
Spinal cord injury leads to a massive response of innate immune cells in non-regenerating mammals, but also in successfully regenerating zebrafish. However, the role of the immune response in successful regeneration is poorly defined. Here we show that inhibiting inflammation reduces and promoting it accelerates axonal regeneration in spinal-lesioned zebrafish larvae. Mutant analyses show that peripheral macrophages, but not neutrophils or microglia, are necessary for repair. Macrophage-less irf8 mutants show prolonged inflammation with elevated levels of Tnf-α and Il-1β. Inhibiting Tnf-α does not rescue axonal growth in irf8 mutants, but impairs it in wildtype animals, indicating a pro-regenerative role of Tnf-α. In contrast, decreasing Il-1β levels or number of Il-1β+ neutrophils rescue functional regeneration in irf8 mutants. However, during early regeneration, interference with Il-1β function impairs regeneration in irf8 and wildtype animals. Hence, inflammation is dynamically controlled by macrophages to promote functional spinal cord regeneration in zebrafish
Setting benchmarks for modelling gas–surface interactions using coherent control of rotational orientation states
A fundamental and predictive understanding of molecule-surface interactions is challenging to obtain. Here the authors report an experimental technique allowing direct measurement of the scattering matrix, which reports on the coherent evolution of quantum states of a molecule scattering from a surface
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