Non-spherical Distribution Research Articles

Massive star cluster formation

Two main mechanisms have classically been proposed for the formation of runaway stars. In the binary supernova scenario (BSS), a massive star in a binary explodes as a supernova, ejecting its companion. In the dynamical ejection scenario, a star is ejected during a strong dynamical encounter between multiple stars. We propose a third mechanism for the formation of runaway stars: the subcluster ejection scenario (SCES), where a subset of stars from an infalling subcluster is ejected out of the cluster via a tidal interaction with the contracting gravitational potential of the assembling cluster. We demonstrate the SCES in a star-by-star simulation of the formation of a young massive cluster from a 106 M⊙ gas cloud using the TORCH framework. This star cluster forms hierarchically through a sequence of subcluster mergers determined by the initial turbulent, spherical conditions of the gas. We find that these mergers drive the formation of runaway stars in our model. Late-forming subclusters fall into the central potential, where they are tidally disrupted, forming tidal tails of runaway stars that are distributed highly anisotropically. Runaways formed in the same SCES have similar ages, velocities, and ejection directions. Surveying observations, we identify several SCES candidate groups with anisotropic ejection directions. The SCES is capable of producing runaway binaries: two wide dynamical binaries in infalling subclusters were tightened through ejection. This allows for another velocity kick via subsequent via a subsequent BSS ejection. An SCES-BSS ejection is a possible avenue for the creation of hypervelocity stars unbound to the Galaxy. The SCES occurs when subcluster formation is resolved. We expect nonspherical initial gas distributions to increase the number of calculated runaway stars, bringing it closer to observed values. The observation of groups of runaway stars formed via the SCES can thus reveal the assembly history of their natal clusters.

A connection between the Darwin term and a nonspherical charge distribution

A derivation of the Darwin term is given based on assuming a nonspherical charge distribution. The total translational energy of the system is obtained for a static electric field, and the corresponding quantum equation is found to contain the Darwin term under certain conditions.

Influence of Rolling Resistance and Particle Size Distribution in the Simulation of Sand Infiltration into the Static Gravel Bed

Fine sediment infiltration and subsequent clogging in a gravel bed affect several fluvial, ecological, and biological processes, resulting in the degradation of the river ecosystem. Despite many experimental and a few numerical studies, the process is yet to be entirely understood. We employed a pure Lagrangian framework, called the Discrete Element Method (DEM), to numerically investigate the infiltration process. Special attention is given to tackling the issue of non-spherical and irregular particle shapes and particle size distributions (PSDs) in numerical simulations. Due to computational limitations, these aspects were either not considered or simplified in previous numerical studies. We implicitly included non-spherical and irregular shape effects through rolling resistance models, which do not cause excessive computational overhead. Our study shows that rolling resistance models greatly influence packing and fine sediment infiltration. However, they may also lead to unphysical particle behavior; thus, they should be carefully used in numerical simulations. Oversimplified PSDs do not mirror natural systems, and full PSDs pose computational challenges. Sufficient grain classes are needed to mimic the non-homogeneity and poly-dispersity found in natural fluvial sediments. The infiltrating characteristics of sand concerning PSD and shape effects are linked to size ratio D15,Gravel/D85,Sand, assuring physical and realistic modeling of the infiltration process.

Energy density source levels of underwater explosive charges

This paper presents experimental measurements of energy density source levels of small explosive charges for high frequencies to 18 kHz. The experiments were carried out using Signals Underwater Sound (SUS) charges deployed at a deep water site in a coastal fiord north of Vancouver BC. The waveform of an underwater explosion is characterized by a high intensity shock wave signal followed by a series of bubble pulses of decreasing intensity. The bubble pulses dominate the SUS energy density spectrum at frequencies below 1 kHz, but at higher frequencies the spectrum is dominated by the characteristics of the decay envelope of the shock wave signal. The explosive material in SUS charges is packed in a thin cylindrical cavity, resulting in a non-uniform decay envelope with secondary pulses when detonated, and a non-spherical distribution of the radiated sound. The impact of the cylindrical charge shape on energy density source level was investigated experimentally. Data were recorded for SUS deployments that generated in-line and broadside sound propagation to the receiver with respect to the axis of the cylindrical charge. Experimental measurements indicate significant differences in the high frequency SUS energy density spectrum depending upon the SUS and receiver geometry.

PRLDPC: A Heuristics Prototype Reduction Method Based on Supervised Local Density Clustering for Instance-Based Classifiers

The prototype reduction (PR) methods, as an important data pre-processing task, can improve instance-based classifiers by removing noise and/or redundant samples. Recently, a series of PR methods with different heuristic strategies have been developed. Among them, clustering-based PR methods have shown competitive performance. Yet, they still suffer from the following issues: (a) most methods heavily rely on parameters; (b) most fail to remove suspicious noisy samples from the training set; (c) almost all fail to handle manifold data with nonspherical distributions effectively; (d) some have a relatively high time complexity. To advance the state of the art of clustering-based PR methods by overcoming the above issues, a novel heuristics PR method based on supervised local density peaks clustering (PRLDPC) is proposed. The main ideas of PRLDPC are concluded as follows: (a) a supervised local density peaks clustering (SLDPC) is first proposed to divide the training set into homogeneous and heterogeneous sub-clusters; (b) SLDPC-based edition method is second proposed to identify and remove noisy samples from heterogeneous sub-clusters; (c) an SLDPC-based condensing method is third proposed to obtain reduced samples from homogeneous sub-clusters and pruned heterogeneous sub-clusters. Intensive experiments have proven that (a) PRLDPC can outperform six state-of-the-art PR methods on extensive UCI and Kaggle data sets in weighing the reduction rate and classification accuracy of three instance-based classifiers; (b) PRLDPC is relatively fast and has a relatively low time complexity [Formula: see text].

Electromagnetic properties of the Σc(2800)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma _{c}(2800)^+$$\\end{document} and Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states via light-cone QCD

The Σc(2800)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma _{c}(2800)^+$$\\end{document} and Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states are among the most interesting and intriguing particles whose internal structures have not yet been elucidated. Inspired by this, the magnetic dipole moments of the Σc(2800)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma _{c}(2800)^+$$\\end{document} and Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states with quantum numbers JP=12-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J^P = \\frac{1}{2}^-$$\\end{document} and JP=32-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J^P = \\frac{3}{2}^-$$\\end{document}, respectively, are analyzed in the framework of QCD light-cone sum rules, assuming that they have a molecule composed of a nucleon and a D(∗)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D^{(*)}$$\\end{document} meson. The magnetic dipole moments are obtained as μΣc+=0.26±0.05μN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu _{\\Sigma _c^{+}}=0.26 \\pm 0.05~\\mu _N$$\\end{document} and μΛc+=-0.31±0.04μN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu _{\\Lambda _c^{+}}=-0.31 \\pm 0.04~\\mu _N$$\\end{document}. The magnetic dipole moment is the leading-order response of a bound system to a weak external magnetic field. It therefore offers an excellent platform to explore the inner organization of hadrons governed by the quark-gluon dynamics of QCD. Comparison of the findings of this analysis with future experimental results on the magnetic dipole moments of the Σc(2800)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma _{c}(2800)^+$$\\end{document} and Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states may shed light on the nature and internal organization of these states. The electric quadrupole and magnetic octupole moments of the Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states have also been calculated, and these values are determined to be QΛc+=(0.65±0.25)×10-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {Q}}_{\\Lambda _c^+} = (0.65 \\pm 0.25) \ imes 10^{-3}$$\\end{document} fm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^2$$\\end{document} and OΛc+=-(0.38±0.10)×10-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal {O}}_{\\Lambda _c^+} = -(0.38 \\pm 0.10) \ imes 10^{-3}$$\\end{document} fm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}, respectively. The values of the electric quadrupole and magnetic octupole moments show a non-spherical charge distribution. We hope that our estimates of the electromagnetic properties of the Σc(2800)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Sigma _{c}(2800)^+$$\\end{document} and Λc(2940)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _c(2940)^+$$\\end{document} states, together with the results of other theoretical studies of the spectroscopic parameters of these states, will be useful for their search in future experiments and will help us to define the exact internal structures of these states.

Magnetic and quadrupole moments of the , , and states in the diquark-antidiquark picture

The magnetic and quadrupole moments of the , , and states are calculated within the QCD light-cone sum rules. The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states. The magnetic moments are acquired as , , and for the , , and states, respectively. The magnetic moments evaluated for the , , and states are sufficiently large to be experimentally measurable. The magnetic moment is an excellent platform for studying the internal structure of hadrons governed by the quark-gluon dynamics of QCD because it is the leading-order response of a bound system to a weak external magnetic field. The quadrupole moment results are , , and for the , , and states, respectively. We obtain a non-zero, but small, value for the quadrupole moments of the states, which indicates a non-spherical charge distribution. The nature and internal structure of these states can be elucidated by comparing future experimental data on the magnetic and quadrupole moments of the , , and states with the results of the present study.

The Bosons of the Conventional Superconductors

For the conventional superconductors it will be shown that not only the superconducting energy gap, Egap(T=0), and the critical field, Bc(T=0), but also the London penetration depth, λL(T=0), scale in a reasonable approximation with the superconducting transition temperature, TSC, as ~TSC, ~TSC2 and ~T-1/2, respectively. From these scaling relations the conclusion obtained earlier, using a completely different method, is confirmed that the London penetration depth corresponds to the diameter of the Cooper-pairs. As a consequence, only one layer of Cooper pairs is sufficient to shield an external magnetic field completely. The large diamagnetism of the superconductors is caused by the large orbital area of the Cooper-pairs. From the fact that, in the zero-field ground state, the temperature dependence of the superconducting heat capacity is given above and below TSC by power functions of absolute temperature it follows that the only critical point is T=0. The superconducting transitions of the element superconductors, therefore, are all within the critical range at T=0. As a consequence, above and below TSC there is short-range order only. As we know from Renormalization Group (RG) theory, in the critical range the dynamics is the dynamics of a boson field, exclusively. Evidently, the Cooper-pairs have to be considered as the short-range ordered units created by this boson field. It is reasonable to assume that the relevant bosons in the superconducting state are identical with the bosons giving rise to the universal linear-in-T electronic heat capacity above TSC. Plausibility arguments will be given that these bosons must be electric quadrupole radiation generated by the non-spherical charge distributions in the soft zones between the metal atoms. The radiation field emitted by an electric quadrupole can be assumed to be essentially curled or circular. In the ordered state below TSC, the bosons are condensed in resonating spherical modes which encapsulate the two Cooper-pair electrons and shield their charge perfectly.

On the origins of spontaneous spherical symmetry-breaking in open-shell atoms through polymer self-consistent field theory.

An alternative approach to density functional theory based on self-consistent field theory for ring polymers is applied to neutral atoms hydrogen to neon in their ground-states. The spontaneous emergence of an atomic shell structure and spherical symmetry-breaking of the total electron density are predicted by the model using the ideas of polymer excluded-volume between pairs of electrons to enforce the Pauli-exclusion principle and an exact electron self-interaction correction. The Pauli potential is approximated by neglecting inter-atomic correlations along with other types of correlations, and comparisons to Hartree-Fock theory are made, which also ignores correlations. The model shows excellent agreement with Hartree-Fock theory to within the standards of orbital-free density functional theory for the atomic binding energies and density profiles of the first six elements, providing exact matches for the elements hydrogen and helium. The predicted shell structure starts to deviate significantly past the element neon, and spherical symmetry-breaking is first predicted to occur at carbon instead of boron. The self-consistent field theory energy functional that describes the model is decomposed into thermodynamic components to trace the origin of spherical symmetry-breaking. It is found to arise from the electron density approaching closer to the nucleus in non-spherical distributions, which lowers the energy despite resulting in frustration between the quantum kinetic energy, electron-electron interaction, and the Pauli exclusion interaction. The symmetry-breaking effect is found to have a minimal impact on the binding energies, which suggests that the spherical-averaging approximation used in previous work is physically reasonable when investigating atomic systems. The pair density contour plots display behavior similar to polymer macro-phase separation, where individual electron pairs occupy single lobe structures that together form a dumbbell shape analogous to the 2p orbital shape. It is further shown that the predicted densities satisfy known constraints and produce the same total electronic density profile that is predicted by other formulations of quantum mechanics.

Electromagnetic form factors of the Bc-like tetraquarks: Molecular and diquark-antidiquark pictures

In this study, we use the molecular and diquark-antidiquark tetraquark pictures to investigate magnetic and quadrupole moments of the Bc-like ground state tetraquarks with the QCD light-cone sum rules with quantum numbers JP=1+. In the numerical analysis, to obtain the magnetic and quadrupole moments of Bc-like tetraquark states molecular and diquark-antidiquark forms of interpolating currents, and photon distribution amplitudes have been used. The magnetic moments are acquired as μZucu¯b¯Mol=1.18−0.40+0.52μN, μZucu¯b¯Di=3.05−0.95+1.19μN, μZdcd¯b¯Mol=0.32−0.10+0.18μN, and μZdcd¯b¯Di=2.38−0.75+0.95μN. The hadrons' magnetic and quadrupole moments are another fundamental observable as their mass, which provides information on the underlying quark structure and dynamics. The results obtained in both pictures are quite different from each other. Any experimental measurement of the magnetic moments can provide an understanding of the internal structure of these states. We get nonzero but small values for the quadrupole moments of Bc-like tetraquark states showing non-spherical charge distributions. Hopefully, the examinations given in this study will be helpful to an experimental search of them, which will be an interesting research subject.

First-principles calculations to investigate mechanical, electronic, optical, and thermodynamic properties of Zr-based ternary compounds

In the present work, a computationally efficient and accurate methodology based on density functional theory is adopted to expound the structural characteristics, elastic, electronic, optical, and thermodynamic properties of zirconium (Zr)-boron (B)-Iridium (Ir) ternary compounds. The current calculated results reveal that Zr–B–Ir ternary compounds except for the Zr4B15Ir12 are dynamically stable phases at 0 K owing to their positive phonon dispersions. Additionally, C–Zr2BIr6 exhibits the best thermodynamic stability due to its lowest formation enthalpy of −0.974 eV/atom in all calculated Zr–B–Ir compounds. C–Zr2BIr6 phase has the maximum bulk and Young's modulus (E) of 151.18 and 382.51 GPa, showing it has a good stiffness due to its higher E. In addition, the elastic anisotropies of the Zr–B–Ir system are complied with the following order: ZrB4Ir3 > T-Zr2BIr6 > Zr4B15Ir12 > C–Zr2BIr6. The non-spherical distribution of electrons for the C–Zr2BIr6 compound plays a blocking role in preventing the deformation, which is beneficial to enhance the comprehensive properties. The B–Ir bond has the shortest length compared to other bond types, resulting in a higher modulus. Lastly, T-Zr2BIr6 has a better storage optical property due to its larger optical conductivity and energy loss function.

Inversion Model of Nonspherical Aerosol Particle Size Distribution Based on Tikhonov’s Regularization With the PSO-GA Algorithm

Inversion Model of Nonspherical Aerosol Particle Size Distribution Based on Tikhonov’s Regularization With the PSO-GA Algorithm

Electromagnetic properties of doubly heavy pentaquark states

Motivated by the latest discovery of doubly charmed tetraquark \(T^+_{cc}\) by LHCb collaboration, we have studied the magnetic moments of the possible doubly heavy pentaquark states with quantum numbers \(J^P = 1/2^-\) and \(J^P = 3/2^-\) within the light-cone sum rules method. In the analysis, these possible pentaquark states are considered in diquark–diquark–antiquark structure. The magnetic moments of hadrons encode helpful details about the distributions of the charge and magnetization inside the hadrons, which help us to figure out their geometric configurations. As a by-product, the electric quadrupole and magnetic octupole moments of the spin − 3/2 doubly heavy pentaquark states are also extracted. These values show a non-spherical charge distribution. It will be interesting and useful to examine the magnetic moments of these possible doubly heavy pentaquark states with different theoretical approaches.

Electromagnetic properties of the $$ D \bar{D}^* K$$ molecular hexaquark state

We systematically study the electromagnetic properties of multiquark states. In this study, inspired by the recent series of studies that showed the likely existence of a $$ D \bar{D}^* K$$ state, we examine the magnetic moment of $$ D \bar{D}^* K$$ hexaquark state in three-meson molecular structure, as well as having isospin and spin-parity quantum numbers $$I(J^P) =3/2(1^-)$$ via light-cone sum rules. The magnetic moment obtained for the $$ D \bar{D}^* K$$ molecular hexaquark state is quite large due to the double electric charge, and its magnitude indicates that it is accessible in future experiments. As a byproduct, the quadrupole moment of the $$ D \bar{D}^* K$$ molecular hexaquark state is also extracted. This value indicates a non-spherical charge distribution. The magnetic moments of hadrons contains valuable knowledge on the distributions of charge and magnetization their inside, which can be used to better understand their geometric shape and quark-gluon organizations. The results given in this study constitute an estimate of the magnetic moment of this $$D \bar{D}^* K$$ state and should serve as an inspiration to conduct experimental examinations of this state.

A Graph Adaptive Density Peaks Clustering algorithm for automatic centroid selection and effective aggregation

As a clustering approach based on density, Density Peaks Clustering algorithm (DPC) has conspicuous superiorities in searching and finding density peaks. Nevertheless, DPC has obvious deficiencies in centroid selection and aggregation process affected by differences in data shape and density distribution, which can easily cause problems in centroid selection and trigger domino effect. Therefore, a Graph Adaptive Density Peaks Clustering algorithm based on Graph Theory (called GADPC) is proposed to automatically select centroid and aggregate more effectively. The improvement of GADPC can be subdivided into the two steps. First, the clustering centroids are automatically selected based on the turning angle θ and the graph connectivity of centroids. Second, the remaining points are aggregated towards the corresponding clustering centroid. According to the improved principle, they belong to the closer point which has stronger graph connectivity and higher density. Theoretical analyses and experimental data indicate that GADPC, compared with DBSCAN, K-means and DPC, is more feasible and effective in processing some data sets with varying density and non-spherical distribution such as Jain and Spiral.

Kinematics, structure and abundances of supernova remnant 0540-69.3

Aims. Our goal is to investigate the structure, elemental abundances, physical conditions, and the immediate surroundings of supernova remnant 0540-69.3 in the Large Magellanic Cloud. Methods. Imaging in [O III] and spectroscopic studies through various slits were carried out using European Souther Observatory’s Very Large and New Technology Telescopes. Densities, temperatures, and abundances were estimated applying nebular analysis for various parts of the remnant. Results. Several new spectral lines are identified, both from ejecta embedded in the pulsar-wind nebula, and in interstellar clouds shocked by the supernova blast wave. For the filaments in the pulsar-wind nebula, all lines are redshifted by 440 ± 80 km s−1 with respect to the rest frame of the host galaxy, and a 3D representation of the [O III] emission displays a symmetry axis of ring-like structures which could indicate that the pulsar shares the same general redshift as the central supernova ejecta. We note that [O II], [S II], [Ar III], and Hβ share a common more compact structure than [O III], and possibly [Ne III]. The average [O III] temperature for the filaments in the pulsar-wind nebula is 23 500 ± 1800 K, and the electron density derived from [S II] is typically ∼ 103 cm−3. By mass, the relative elemental abundances of the shocked ejecta in the pulsar-wind nebula are O : Ne : S : Ar ≈ 1 : 0.07 : 0.10 : 0.02, consistent with explosion models of 13 − 20 M⊙ progenitors, and similar to that of SN 1987A, as is also the explosive mixing of hydrogen and helium into the center. From Hβ and He Iλ5876, the mass ratio of He/H in the center is estimated to be in excess of ∼0.8. The rapid cooling of the shocked ejecta could potentially cause variations in the relative abundances if the ejecta are not fully microscopically mixed, and this is highlighted for S/O for the period 1989–2006. Also, [O III] is seen in presumably freely coasting photoionized ejecta outside the pulsar-wind nebula at inferred velocities out to well above 2000 km s−1, and in projection, [O III] is seen out to ∼10″ from the pulsar. This was used to estimate that the pulsar age is ≈1200 years. The freely coasting [O III]-emitting ejecta have a strictly nonspherical distribution, and their mass is estimated to be ∼0.12 M⊙. A possible outer boundary of oxygen-rich ejecta is seen in [O II] λλ3726,3729 at ∼2000 − 2100 km s−1. Four filaments of a shocked interstellar medium are identified, and there is a wide range in the degree of ionization of iron, from Fe+ to Fe13+. One filament belongs to a region also observed in X-rays, and another one has a redshift of 85 ± 30 km s−1 relative to the host. From this we estimate that the electron density of the [O III]-emitting gas is ∼ 103 cm−3, and that the line of the most highly ionized ion, [Fe XIV] λ5303, comes from an evaporation zone in connection with the radiatively cooled gas emitting, for example, [O III], and not from immediately behind the blast wave. We do not find evidence for nitrogen-enriched ejecta in the southwestern part of the remnant, as was previously suggested. Emission in this region is instead from a severely reddened H II-region.

Prediction of heptagonal bipyramidal nonacoordination in highly viable [OB-M\xa9B7O7-BO]\u2212 (M\u2009=\u2009Fe, Ru, Os) complexes

Non-spherical distributions of ligand atoms in coordination complexes are generally unfavorable due to higher repulsion than for spherical distributions. To the best of our knowledge, non-spherical heptagonal bipyramidal nonacoordination is hitherto unreported, because of extremely high repulsion among seven equatorial ligand atoms. Herein, we report the computational prediction of such nonacoordination, which is constructed by the synergetic coordination of an equatorial hepta-dentate centripetal ligand (B7O7) and two axial mono-dentate ligands (-BO) in the gear-like mono-anionic complexes [OB-M©B7O7-BO]– (M = Fe, Ru, Os). The high repulsion among seven equatorial ligand B atoms has been compensated by the strong B–O bonding. These complexes are the dynamically stable (up to 1500 K) global energy minima with the HOMO-LUMO gaps of 7.15 to 7.42 eV and first vertical detachment energies of 6.14 to 6.66 eV (being very high for anions), suggesting their high probability for experimental realization in both gas-phase and condensed phases. The high stability stems geometrically from the surrounded outer-shell oxygen atoms and electronically from meeting the 18e rule as well as possessing the σ + π + δ triple aromaticity. Remarkably, the ligand-metal interactions are governed not by the familiar donation and backdonation interactions, but by the electrostatic interactions and electron-sharing bonding.

Judging phase purity of hematite (α-Fe2O3) nanoparticles through structural and magnetic studies

The effect of post-growth annealing on the phase transformation leading to phase pure hematite (α-Fe2O3) nanoparticles is reported in this work. Co-precipitation technique was used to synthesise iron oxide nanoparticles by adjusting the pH of the solution. The xerogel was dried at 80 °C and the obtained powder was calcined in the temperature range 400–800 °C for 3 h. in air. Annealing temperature was prefixed on the basis of the thermal degradation pattern of the starting precursor. X-ray diffraction (XRD) study endorsed the presence of mixed phases FeO, FeO2 and α-Fe2O3 in the as-prepared sample. On annealing, the minor phases transform gradually to α-Fe2O3, as confirmed through thermal studies. Performed Rietveld analysis confirms the presence of impurity phases in samples annealed at low temperature. Phase pure sample crystallizes in the rhombohedral corundum structure (space group, R-3c) with a = 5.04044 Å, c = 13.7628 Å and c/a = 2.73048. FT-Raman spectral investigations allowed for a clear assignment of the α-Fe2O3 phase. Chemical analysis advocated the only presence of Fe3+ ions that octahedrally coordinated with hexagonally close packed O2- ions that constitute corundum structure. Electron microscopy (TEM) images proved the non-spherical particle distribution in the range 80–100 nm with mean particle size of 93 nm. Structural phase transition with annealing temperature was further confirmed through the fluctuations in the magnetic structure. In analogues to XRD, magnetic study also served as a judging tool to identify purity and the presence of mixed phases in hematite.

Magnetic dipole moments of the hidden-charm pentaquark states: P_c(4440), P_c(4457) and P_{cs}(4459)

In this work, we employ the light-cone QCD sum rule to calculate the magnetic dipole moments of the P_c(4440), P_c(4457) and P_{cs}(4459) pentaquark states by considering them as the diquark–diquark–antiquark and molecular pictures with quantum numbers J^P = frac{3}{2}^-, J^P = frac{1}{2}^- and J^P = frac{1}{2}^-, respectively. In the analyses, we use the diquark–diquark–antiquark and molecular form of interpolating currents, and photon distribution amplitudes to obtain the magnetic dipole moment of pentaquark states. Theoretical examinations on magnetic dipole moments of the hidden-charm pentaquark states, are essential as their results can help us better figure out their substructure and the dynamics of the QCD as the theory of the strong interaction. As a by product, we extract the electric quadrupole and magnetic octupole moments of the P_c(4440) pentaquark. These values show a non-spherical charge distribution.

Wind mass transfer in S-type symbiotic binaries

Context. The structure of the wind from the cool giants in symbiotic binaries carries important information for understanding the wind mass transfer to their white dwarf companions, its fuelling, and thus the path towards different phases of symbiotic-star evolution. Aims. In this paper, we indicate a non-spherical distribution of the neutral wind zone around the red giant (RG) in the symbiotic binary star, EG And. We concentrate in particular on the wind focusing towards the orbital plane and its asymmetry alongside the orbital motion of the RG. Methods. We achieved this aim by analysing the periodic orbital variations of fluxes and radial velocities of individual components of the Hα and [O III] λ5007 lines observed on our high-cadence medium (R ∼ 11 000) and high-resolution (R ∼ 38 000) spectra. Results. The asymmetric shaping of the neutral wind zone at the near-orbital-plane region is indicated by: (i) the asymmetric course of the Hα core emission fluxes along the orbit; (ii) the presence of their secondary maximum around the orbital phase φ = 0.1, which is possibly caused by the refraction effect; and (iii) the properties of the Hα broad wing emission originating by Raman scattering on H0 atoms. The wind is substantially compressed from polar directions to the orbital plane as constrained by the location of the [O III] λ5007 line emission zones in the vicinity of the RG at/around its poles. The corresponding mass-loss rate from the polar regions of ≲10−8 M⊙ yr−1 is a factor of ≳10 lower than the average rate of ≈10−7 M⊙ yr−1 derived from nebular emission of the ionised wind from the RG. Furthermore, it is two orders of magnitude lower than that measured in the near-orbital-plane region from Rayleigh scattering. Conclusions. The startling properties of the nebular [O III] λ5007 line in EG And provides an independent indication of the wind focusing towards the orbital plane – the key to understanding the efficient wind mass transfer in symbiotic binary stars.