Search results for "ground"
showing 10 items of 2432 documents
Background subtraction and peak search from threefold gamma event data
1990
Abstract A method for subtracting background from triple-coincidence γ events is presented. In our data set it was used to remove 40% of the noise without affecting photopeaks with intensity of >18 counts. An example of performance of Ward's clustering algorithm applied to three-dimensional photopeak searching is also presented. Several standard clustering algorithms were found to be applicable only to background-subtracted data.
Exudate-based diabetic macular edema detection in fundus images using publicly available datasets
2010
International audience; Diabetic macular edema (DME) is a common vision threatening complication of diabetic retinopathy. In a large scale screening environment DME can be assessed by detecting exudates (a type of bright lesions) in fundus images. In this work, we introduce a new methodology for diagnosis of DME using a novel set of features based on colour, wavelet decomposition and automatic lesion segmentation. These features are employed to train a classifier able to automatically diagnose DME through the presence of exudation. We present a new publicly available dataset with ground-truth data containing 169 patients from various ethnic groups and levels of DME. This and other two publi…
Revelation of aroma potential of grape pomace and spent coffee ground by the use of microbial glycosidases.
2021
The food industry is evolving and tends to reduce its environmental impact, to control its waste and to valorise all of its production. Grapes and coffee are among the main agricultural products in the world and not all of the byproducts resulting from their processing are still valued today. New ways of valorisation are seeked in order to limit production losses. Yet, these byproducts are rich in glycosides, the amount of which may be from two to five times greater than that of the free volatile compounds. Grape pomace and spent coffee ground could be used to naturally produce volatile compounds from their glycosides. These volatile compounds could be useful in the production of cosmetics,…
Charge distribution and optical properties of and F centres in crystals
1997
Results of quantum chemical calculations for the and F centres in cubic and orthorhombic phases of a perovskite ferroelectric are presented and analysed in the light of existing experimental literature. It is shown that one (two) electrons of the and F centres, respectively, are considerably delocalized, even in the ground state of defects, over the two Nb atoms nearest to the O vacancy, and other close atoms. They resemble more electron defects in partly covalent crystals (the so-called centre) than F-type centres in ionic MgO crystals. We predict two or three absorption bands (depending on the crystalline phase) for each of the defects. The calculated absorption energies for the centre ar…
High nuclearity mixed-valence magnetic clusters: theoretical study of the spin coupling in the C602− fulleride ion
1998
Abstract The problem of delocalization of a pair of electrons over the fullerene C 60 is considered, with the aim of elucidating the nature of the ground spin state, as well as the structure of the low-lying energy levels in this mixed-valence molecule C 60 2− . A model that considers the Coulomb interactions between the two extra electrons, as well as the two single-electron transfer processes involved in the electron delocalization, is developed. The influence of these electronic parameters on the spectrum of the low-lying energy levels is discussed. We find that the ground state is always a spin singlet, whatever the relative values of these parameters are.
Phase diagram of the quarter-filled extended Hubbard model on a two-leg ladder
2000
We investigate the ground-state phase diagram of the quarter-filled Hubbard ladder with nearest-neighbor Coulomb repulsion V using the Density Matrix Renormalization Group technique. The ground-state is homogeneous at small V, a ``checkerboard'' charge--ordered insulator at large V and not too small on-site Coulomb repulsion U, and is phase-separated for moderate or large V and small U. The zero-temperature transition between the homogeneous and the charge-ordered phase is found to be second order. In both the homogeneous and the charge-ordered phases the existence of a spin gap mainly depends on the ratio of interchain to intrachain hopping. In the second part of the paper, we construct an…
Stripe formation in doped Hubbard ladders
2004
We investigate the formation of stripes in $7\chunks \times 6$ Hubbard ladders with $4\chunks$ holes doped away from half filling using the density-matrix renormalization group (DMRG) method. A parallelized code allows us to keep enough density-matrix eigenstates (up to $m=8000$) and to study sufficiently large systems (with up to $7\chunks = 21$ rungs) to extrapolate the stripe amplitude to the limits of vanishing DMRG truncation error and infinitely long ladders. Our work gives strong evidence that stripes exist in the ground state for strong coupling ($U=12t$) but that the structures found in the hole density at weaker coupling ($U=3t$) are an artifact of the DMRG approach.
GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences
2018
The LIGO Scientific and Virgo Collaborations have announced the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star background will add to the background from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude $\Omega_{\rm…
Solutions for the Design and Increasing of Efficiency of Viscous Dampers
2016
In last decades many strategies for seismic vulnerability mitigation of structures have been studied and experimented; in particular energy dissipation by external devices assumes a great importance for the relative simplicity and efficacy. Among all possible approaches the use of fluid viscous dampers are very interesting, because of their velocity-dependent behaviour and relatively low costs. Application on buildings requires a specific study under seismic excitation and a particular attention on structural details. Nevertheless seismic codes give only general information and in most case the design of a such protection systems results difficult; this problem is relevant also in Italy whe…
Towards Dialogic Teaching in Science: Challenging Classroom Realities through Teacher Education.
2013
Lehesvuori, Sami Towards Dialogic Teaching in Science: Challenging Classroom Realities through Teacher Education Jyvaskyla: University of Jyvaskyla, 2013, 87 p. (Jyvaskyla Studies in Education, Psychology and Social Research ISSN 0075-4625; 465) ISBN 978-951-39-5151-1 (nid.) ISBN 978-951-39-5152-8 (PDF) Diss. Finnish summary The aim of this study was to explore dialogic teaching in school classroom and teacher education contexts. Despite moves towards more socially-oriented and student-centred curricula, science classroom communication remains prevailingly authoritative and monologic. In order to address the dialogic gap existing in the field, within this study an intervention was developed…