Semiautomatic epicardial fat segmentation based on fuzzy c-means clustering and geometric ellipse fitting

Automatic segmentation of particular heart parts plays an important role in recognition tasks, which is utilized for diagnosis and treatment. One particularly important application is segmentation of epicardial fat (surrounds the heart), which is shown by various studies to indicate risk level for developing various cardiovascular diseases as well as to predict progression of certain diseases. Quantification of epicardial fat from CT images requires advance image segmentation methods. The problem of the state-of-the-art methods for epicardial fat segmentation is their high dependency on user interaction, resulting in low reproducibility of studies and time-consuming analysis. We propose in this paper a novel semiautomatic approach for segmentation and quantification of epicardial fat from 3D CT images. Our method is a semisupervised slice-by-slice segmentation approach based on local adaptive morphology and fuzzy c-means clustering. Additionally, we use a geometric ellipse prior to filter out undesired parts of the target cluster. The validation of the proposed methodology shows good correspondence between the segmentation results and the manual segmentation performed by physicians

Isotope Effects in Molecule Assisted Recombination and Dissociation in Divertor Plasmas

A burning fusion plasma will necessarily contain a mixture of D and T iso-topes, in the atomic, molecular and ionised components. It is demonstrated that molecule assisted recombination (MAR) and dissociation (MAD) mech-anisms expected to be strong in typical low-temperature hydrogenic diver-tor plasmas exhibit a kinetic isotope effect. The effect originates from the mass dependence of rate coeffcients of dissociative electron attachment and atomic-to-molecular ion conversion reactions, that are common precursors for MAR and MAD mechanisms. MAR favours a faster recombbination of the lighter ion with plasma electrons, while MAD favours a faster dissociation of the lighter molecule. The effect is cumulative, and during the ion residence time in the divertor it may produce significant differences in the recombined electron-ion pairs of the two isotopes, and in the amounts of dissociation products of the two isotopic molecules. For example a factor of 3 - 9 in MAR, and 22 - 400 in MAD in the concentrations of recombination and dissociation products results, for T = 3 eV, n$_{e}$ = 3 $\cdot$ 10$^{14}$ cm$^{-3}$ and [H$_{2}$]:[D$_{2}$]:[HD] in the range 1:1:0 - 1:1:2. Some implications of MAR and MAD isotope effects for divertor plasma physics are discussed

Alignment of H(2p) in collisions of protons and antiprotons with hydrogen atoms with screened Coulomb interaction

The effects of screened Coulomb interaction on the alignment of H(2p) state produced in collisions of hydrogen atoms with protons and antiprotons are investigated in the energy range 1–200 keV by using the two-center atomic orbital close-coupling (TC-AOCC) method. It is shown that the decrease of the binding energy of hydrogen nl-states and the reduction of the number of bound states with increasing the strength of the screening affect significantly the alignment degree and its energy dependence. In the case of antiproton-H collision the difference between the alignments with screened and unscreened Coulomb potential increases with increasing the strength of the screening in the entire energy range above 2 keV/u, while in the case of proton-H collision it does so only in the energy range 5–25 keV/u

Electron capture and excitation in H

The processes of state-selective electron capture and excitation in proton collisions with Li+(1s2 1S) and Li+(1s2s 1,3S) ions are studied by using the two-center atomic orbital close-coupling (TC-AOCC) methods in the energy range 2.5–800 keV. The interaction of the active electron with the Li2+ ion core is represented by model potentials that reproduce the energies of excited singlet and triplet states of Li+ with accuracy better than 2%. The expansion basis in the coupled state calculations includes all states with n ≤ 8 (in total 120 states) centered on each of the colliding centers. Total and state-selective electron capture and excitation cross sections to final states with n ≤ 4 are presented. The physical mechanisms involved in the dynamics of considered processes are discussed in detail. The reported cross sections should be useful in the kinetic modeling and diagnostics of fusion reactor plasmas with liquid lithium divertors

Electron capture, excitation and ionization processes in He

Electron capture, excitation and ionization processes in He2+–H collisions taking place in quantum plasmas are studied by employing the two-center atomic orbital close coupling (TC-AOCC) method. The Debye-Hückel-cosine (DHC) potential is used to describe the plasma screening effects on the Coulomb interaction between charged particles. The properties of eigenenergies of hydrogen-like atom with DHC potential are investigated as function of the screening length of the potential. It is found that the binding energies of nl states decrease with decreasing the screening length of the potential. The dynamics of excitation, electron capture and ionization processes in He2+–H collision system is investigated when the screening length of the potential varies for a wide collision energy range. The TC-AOCC cross sections are compared with those for the pure Coulomb potential and, for the total electron capture, with the results of classical trajectory Monte Carlo method

Collision processes of hydrocarbon species in hydrogen plasmas 3: The silane family

Cross sections are provided for most important collision processes of the Silicon-Hydrides from the "Silane-family": SiH$_{y}$ (y = 1 - 4) molecules and their ions SiH$^{+}_{y}$, with (plasma) electrons and protons. The processes include: electron impact ionization and dissociation of SiH$_{y}$, dissociative excitation, ionization and recombination of SiH$^{+}_{y}$ ions wich electrons, and charge - and atom - exchange in proton collisions with SiH$_{y}$. All important channels of dissociative processes are considered. Information is also provided an the energetics (reactants/products energy loss / gain) of each individual reaction channel. Total and partial cross sections are presented in compact analytic forms. The critical assessment of data, derivation of new data and presentation of results follow closely the concepts of the recently published related databases for Carbon-Hydrides, namely for the Methane family [1, 2], and for the Ethane- and the Propane families [3], respectively

Cross sections for electron capture and excitation in proton collisions with the metastable Be(2s2p

The two-center atomic orbital close-coupling method is employed to study electron capture and excitation processes in proton collisions with the metastable Be(1s2s2p P) atom. The interaction of the active electron with the Be ion core is represented by a model potential reproducing accurately (to within 3.5%) the energies of triplet excited states Be(1s2snl L) (at least up to n = 7). The excitation and state-selective electron capture cross sections up to the n = 5 shells of both centers are calculated in the energy range 1–200 keV/u using an expansion basis involving all the states with n ≤ 7 on H and all triplet states with n ≤ 7 on Be, augmented with a number of pseudostates. In the energy region below ~10 keV/u, the cross sections of both processes exhibit oscillatory structures, resulting from the multistate coupling accounted for in the dynamical model. It has been found that the magnitude of excitation cross sections above ~10 keV/u is dominated by the multipole interactions, while below this energy the excitation process proceeds through intermediate electron capture states

Collision processes of hydrocarbon species in hydrogen plasmas I : the methane family

Cross sections and rate coefficients are provided for collision processes of CH$_{y}$ and CH$^{+}_{y}$ (1$\le$y$\le$4) hydrocarbon species with electrons and protons in a wide range of collision energy and temperature. The considered processes include: electron impact ionisation and dissociation of CH$_{y}$, dissociative excitation, ionisation and recombination of CH$^{+}_{y}$ wich electrons, and charge- and atom exchange in proton collisions with CH$_{y}$. In dissociative processes all important reaction channels are considered separately. Information is also provided about the energetics for each individual reaction channel. The cross sections and rate coefficients are represented in analytic fit forms

Dissociative electron attachment to H 2 molecules involving the 2 Σ g + resonant Rydberg electronic state

n/