Large-scale Configuration Research Articles

A prematuration approach to equine IVM: considering cumulus morphology, seasonality, follicle of origin, gap junction coupling and large-scale chromatin configuration in the germinal vesicle.

Several studies report that a two-step culture where mammalian oocytes are first kept under meiosis-arresting conditions (prematuration) followed by IVM is beneficial to embryo development. The most promising results were obtained by stratifying the oocyte population using morphological criteria and allocating them to different culture conditions to best meet their metabolic needs. In this study, horse oocytes were characterised to identify subpopulations that may benefit from prematuration. We investigated gap-junction (GJ) coupling, large-scale chromatin configuration and meiotic competence in compact and expanded cumulus-oocyte complexes (COCs) according to follicle size (<1, 1-2, >2cm) and season. Then we tested the effect of cilostamide-based prematuration in compact COCs collected from follicles <1 and 1-2cm in diameter on embryo development. Meiotic competence was not affected by prematuration, whereas COCs from follicles 1-2cm in diameter yielded embryos with a higher number of cells per blastocyst than oocytes that underwent direct IVM (P<0.01, unpaired Mann-Whitney test), suggesting improved developmental competence. Oocytes collected from follicles <1cm in diameter were not affected by prematuration. This study represents an extensive characterisation of the functional properties of immature horse oocytes and is the first report of the effects of cilostamide-based prematuration in horse oocyte IVM on embryo development.

A New Wide-Area Protection Scheme for Single- and Double-Circuit Lines Using 3-D-Phase Surface

The modern power system and complex interconnected smart grid have many parallel transmission lines to increase reliability and security. The current complexity of the large-scale power system configuration has led to cause difficult situations for the relay engineers for system coordination and operating time of the distance relays. A new centralized wide-area monitoring system is used for parallel and single lines protection. A new wide-area main protection system based on phasor measurement units “PMUs” is deployed on a real interconnected large-scale power grid. The main concept of the idea is based on describing by ${\text{differential}}\;{\text{equations}}$ the dynamic operation of the transmission lines during the fault. The differential equations can be solved through paths movement in a ${\text{phase}}\;{\text{diagram}}$ . The time is added as a third axis to the ${\text{phase}}\;{\text{diagram}}$ to enhance the performance in three-dimensional (3D)–Phase Surface. The solution curves corresponding to paths are represented graphically in $3{\text{D}} - {\text{Phase}}\;{\text{Surface}}$ . The ${\text{solution}}\;{\text{curves}}$ can move closely or widely separate from the ${\text{equilibrium}}\;{\text{point}}$ indicating the case of the transmission lines as being faulted or not. The fault on the lines can be precisely recognized using this concept. The simulation of the interconnected system network using ${\text{MATLAB}}/{\text{SIMULINK}}$ is used. The relay showed for the first time a solution for the parallel transmission-lines problems in a wide area.

Theoretical study of 4p5nln'l'LSJstates of Sr ion excited by electron impact on Sr atom

Calculations of energy levels and electron-impact excitation cross sections of the Auger autoionizing states 4p5nln'l'(nl= 4d, 5s, 5p; n'l'= 4d, 5s, 5p, 5d, 6s, 6p, 6d, 7s, 7p) of Sr ion were performed. A large-scale configuration interaction method on the basis of the solutions of Dirac–Fock–Slater equations was used. The cross sections of electron-impact simultaneous ionization and excitation, and Auger decay of the electron-impact excited states of Sr atom to the 4p-core excited autoionizing states of Sr ion were calculated for the first time and used to estimate the intensity of ejected electron lines. Tentative identification of the Auger electron lines of Sr ion registered in a number of experiments is presented.

Relativistic large scale CI calculations of energies, transition rates and lifetimes in Ca-like ions between Co VIII and Zn XI

Energies, E1, E2 and M1 transition rates and lifetimes are reported for the lowest 134 fine-structure levels of the 3p63d2, 3p63d4s, 3p53d3 and 3p63d4p configurations in all Ca-like ions between Co VIII and Zn XI. The calculations have been performed using the multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction (RCI) methods. Important core–valance and core–core electron correlation effects are systematically accounted with large scale configuration interaction expansion. The Breit interaction and leading quantum-electrodynamical (QED) contributions such as the vacuum polarization and self-energy corrections are also included in the RCI calculations. The results are compared with the compiled data from the NIST ASD and other calculations to evaluate the accuracy of the present calculations. Our results have good agreement with previous relativistic many-body perturbation theory (RMBPT) calculations and the data from the NIST ASD, except for Zn XI. Present calculations provide some missing data, especially for Cu X and Zn XI, in the NIST ASD.

Suppression of Coronal Mass Ejections in Active Stars by an Overlying Large-scale Magnetic Field: A Numerical Study

Abstract We present results from a set of numerical simulations aimed at exploring the mechanism of coronal mass ejection (CME) suppression in active stars by an overlying large-scale magnetic field. We use a state-of-the-art 3D magnetohydrodynamic code that considers a self-consistent coupling between an Alfvén wave-driven stellar wind solution, and a first-principles CME model based on the eruption of a flux rope anchored to a mixed-polarity region. By replicating the driving conditions used in simulations of strong solar CMEs, we show that a large-scale dipolar magnetic field of 75 G is able to fully confine eruptions within the stellar corona. Our simulations also consider CMEs exceeding the magnetic energy used in solar studies, which are able to escape the large-scale magnetic field confinement. The analysis includes a qualitative and quantitative description of the simulated CMEs and their dynamics, which reveals a drastic reduction of the radial speed caused by the overlying magnetic field. With the aid of recent observational studies, we place our numerical results in the context of solar and stellar flaring events. In this way, we find that this particular large-scale magnetic field configuration establishes a suppression threshold around ∼3 × 1032 erg in the CME kinetic energy. Extending the solar flare-CME relations to other stars, such CME kinetic energies could be typically achieved during erupting flaring events with total energies larger than 6 × 1032 erg (GOES class ∼X70).

Shell model description of heavy nuclei and abnormal collective motions

In this contribution I present systematic calculations on the spectroscopy and electromagnetic transition properties of intermediate-mass and heavy nuclei around 100Sn and 208Pb. We employed the large-scale configuration interaction shell model approach with realistic interactions. Those nuclei are the longest isotopic chains that can be studied by the nuclear shell model. I will show that the yrast spectra of Te isotopes show a vibrational-like equally spaced pattern but the few known E2 transitions show rotational-like behaviour. These kinds of abnormal collective behaviors cannot be reproduced by standard collective models and provide excellent background to study the competition of single-particle and various collective degrees of freedom. Moreover, the calculated B(E2) values for neutron-deficient and heavier Te isotopes show contrasting different behaviours along the yrast line, which may be related to the enhanced neutron-proton correlation when approaching N=50. The deviations between theory and experiment concerning the energies and E2 transition properties of low-lying 0+ and 2+ excited states and isomeric states in those nuclei may provide a constraint on our understanding of nuclear deformation and intruder configuration in that region.

First principles electron-correlated calculations of optical absorption in magnesium clusters

In this paper, we report large-scale configuration interaction (CI) calculations of linear optical absorption spectra of various isomers of magnesium clusters Mg$_{n}$ (n=2--5), corresponding to valence transitions. Geometry optimization of several low-lying isomers of each cluster was carried out using coupled-cluster singles doubles (CCSD) approach, and these geometries were subsequently employed to perform ground and excited state calculations using either the full-CI (FCI) or the multi-reference singles-doubles configuration interaction (MRSDCI) approach, within the frozen-core approximation. Our calculated photoabsorption spectrum of magnesium dimer (Mg$_{2}$) isomer is in excellent agreement with the experiments both for peak positions, and intensities. Owing to the sufficiently inclusive electron-correlation effects, these results can serve as benchmarks against which future experiments, as well as calculations performed using other theoretical approaches, can be tested.

Accelerating nuclear configuration interaction calculations through a preconditioned block iterative eigensolver

We describe a number of recently developed techniques for improving the performance of large-scale nuclear configuration interaction calculations on high performance parallel computers. We show the benefit of using a preconditioned block iterative method to replace the Lanczos algorithm that has traditionally been used to perform this type of computation. The rapid convergence of the block iterative method is achieved by a proper choice of starting guesses of the eigenvectors and the construction of an effective preconditioner. These acceleration techniques take advantage of special structure of the nuclear configuration interaction problem which we discuss in detail. The use of a block method also allows us to improve the concurrency of the computation, and take advantage of the memory hierarchy of modern microprocessors to increase the arithmetic intensity of the computation relative to data movement. We also discuss the implementation details that are critical to achieving high performance on massively parallel multi-core supercomputers, and demonstrate that the new block iterative solver is two to three times faster than the Lanczos based algorithm for problems of moderate sizes on a Cray XC30 system.

A global approach to perform large-scale configuration–interaction calculations

We present a global approach that allows one to tackle cumbersome configuration–interaction calculations. The method is based on the use of approximate configuration-averaged Hamiltonian matrix elements that can be expressed in compact form as a combination of Slater integrals. With some assumptions, we show that the Hamiltonian matrix to be diagonalized may be reduced to a size equivalent to the number of configurations in the basis set. The approach can be used to estimate shifts of configuration average energies and changes in the total strength of transition arrays. The method is also well suited to work out roughly difficult configuration–interaction calculations, to determine the minimal set of interacting configurations to be used in actual fine-structure calculations.

Disentangling the Complex Vibrational Spectrum of the Protonated Water Trimer, H+(H2O)3, with Two-Color IR-IR Photodissociation of the Bare Ion and Anharmonic VSCF/VCI Theory.

Vibrational spectroscopy of the protonated water trimer provides a stringent constraint on the details of the potential energy surface (PES) and vibrational dynamics governing excess proton motion far from equilibrium. Here we report the linear spectrum of the cold, bare H+(H2O)3 ion using a two-color, IR-IR photofragmentation technique and follow the evolution of the bands with increasing ion trap temperature. The key low-energy features are insensitive to both D2 tagging and internal energy. The D2-tagged D+(D2O)3 spectrum is reported for the first time, and the isotope dependence of the band pattern is surprisingly complex. These spectra are reproduced by large-scale vibrational configuration interaction calculations based on a new full-dimensional PES, which treat the anharmonic effects arising from large amplitude motion. The results indicate such extensive mode mixing in both isotopologues that one should be cautious about assigning even the strongest features to particular motions, especially for the absorptions that occur close to the intramolecular bending mode of the water molecule.

Higher-order perturbative relativistic calculations for few-electron atoms and ions

An effective computational method is developed for electronic-structure calculations in few-electron atoms and ions on the basis of the Dirac-Coulomb-Breit Hamiltonian. The recursive formulation of the perturbation theory provides an efficient access to the higher-order contributions of the interelectronic interaction. Application of the presented approach to the binding energies of lithiumlike and boronlike systems is demonstrated. The results obtained are in agreement with the large-scale configuration interaction Dirac-Fock-Sturm method and other all-order calculations.

Effects of magnetic field topology in black hole-neutron star mergers: Long-term simulations

We report long-term simulations of black hole-neutron star binary mergers where the neutron star possesses an asymmetric magnetic field dipole. Focusing on the scenario where the neutron star is tidally disrupted by the black hole, we track the evolution of the binary up to $\approx 100$ms after the merger. We uncover more than one episode of thermally driven winds being launched along a funnel wall in all these cases beginning from $\approx 25$ms after the merger. On the other hand, we are unable to conclude presently whether the amount of ejected mass increases with the \it{degree} of asymmetry. A large-scale magnetic field configuration in the poloidal direction is formed along the funnel wall accompanied by the generation of a large Poynting flux. The magnetic field in the accretion disk around the black hole remnant is amplified by the nonaxisymmetric magnetorotational instability (MRI). The MRI growth is estimated to be in the ideal magnetohydrodynamics (MHD) regime and thus would be free from significant effects induced by potential neutrino radiation. However, the asymmetry in the magnetic field leads to increased turbulence, which causes the vertical magnetic field in the accretion disk to grow largely in a nonlinear manner.

Simulations of the magnetospheres of accreting millisecond pulsars

Accreting pulsars power relativistic jets and display a complex spin phenomenology. These behaviours may be closely related to the large-scale configuration of the star's magnetic field, shaped by its interaction with the surrounding accretion disc. Here, we present the first relativistic simulations of the interaction of a pulsar magnetosphere with an accretion flow. Our axisymmetric simulations treat the magnetospheric, or coronal, regions using a resistive extension of force-free electrodynamics. The magnetic field is also evolved inside the disc, which is a defined volume with a specified velocity field and conductivity profile, found using an α-disc model. We study a range of disc α-parameters, thicknesses, magnetic Prandtl numbers and inner truncation radii. We find that a large fraction of the magnetic flux in the pulsar's closed zone is opened by the intrusion of the disc, leading to an enhancement of the power extracted by the pulsar wind and the spin-down torque applied to the pulsar. In our simulations, most of the spin-down contribution to the stellar torque acts on open field lines. The efficiency of field-line opening is high in the simulations’ long-term quasi-steady states, which implies that a millisecond pulsar's electromagnetic wind could be strong enough to power the observed neutron-star radio jets, and may significantly affect the pulsar's spin evolution.

Cretaceous sedimentation in the outer Eastern Carpathians: Implications for the facies model reconstruction of the Moldavide Basin

The mid Cretaceous is characterized by high eustatic sea-levels with widespread oxic conditions that made possible the occurrence of globally correlated Oceanic Red Beds. However, very often, these eustatic signals have been overprinted by local tectonics, which in turn resulted in Lower Cretaceous closed and anoxic basins, as in the Eastern Carpathians. There, the black shale to red bed transition occurs in the latest Albian up to the early Cenomanian. Although earlier studies discussed the large-scale basin configuration, no detailed petrography and sedimentology study has been performed in the Eastern Carpathians. This paper describes the Hauterivian to Turonian lithofacies and interprets the depositional settings based on their sedimentological features. The studied sections crop out only in tectonic half windows of the Eastern Carpathians, part of the Vrancea Nappe. The lithofacies comprises black shales interbedded with siderites and sandstones, calcarenites, marls, radiolarites and red shales. The siliciclastic muddy lithofacies in general reflects accumulation by suspension settling of pelagites and hemipelagites in anoxic (black shale) to dysoxic (dark gray and gray to green shales) and oxic (red shales) conditions. The radiolarites alternate with siliceous shales and are considered as evidence of climate changes. The sandstones represent mostly low and high-density turbidite currents in deep-marine lobes, as well as channel/levee systems. The source area is an eastern one, e.g., the Eastern Carpathians Foreland, given the abundance of low grade metamorphic clasts. The Hauterivian – lower Albian sediments are interpreted as deep-marine, linear and multiple sourced mud dominated systems deposited in a mainly anoxic to dysoxic basin. The anoxic conditions existed in the early to late Albian, but sedimentation changed to a higher energy mud/sand-dominated submarine channels and levees. This coarsening upwards tendency is interpreted as the effect of the Aptian to Albian compressional tectonics of the Carpathians. The deepening of the Moldavide Basin from the Cenomanian is most probably linked to a significant sea-level rise.

Effect of Alloying Elements on Nano-ordered Wear Property of Magnesium Alloys

The effect of alloying elements on nano-ordered wear properties was investigated using fine-grained pure magnesium and several types of 0.3 at. pct X (X = Ag, Al, Ca, Li, Mn, Y, and Zn) binary alloys. They had an average grain size of 3 to 5 μm and a basal texture due to their production by the extrusion process. The specific wear rate was influenced by the alloying element; the Mg-Ca and Mg-Mn alloys showed the best and worst wear property, respectively, among the present alloying elements, which was the same trend as that for indentation hardness. Deformed microstructural observations revealed no formation of deformation twins, because of the high activation of grain boundary-induced plasticity. On the contrary, according to scratched surface observations, when grain boundary sliding partially contributed to deformation, these alloys had large specific wear rates. These results revealed that the wear property of magnesium alloys was closely related to the plastic deformation mechanism. The prevention of grain boundary sliding is important to improve the wear property, which is the same as that of a large-scale wearing configuration. One of the influential factors is the change in the lattice parameter with the chemical composition, i.e., ∂(c/a)/∂C. An alloying element that has a large value of ∂(c/a)/∂C effectively enhances the wear property.

Position of the nucleus in mouse germinal vesicle–stage oocytes with different chromatin configurations

The mammalian germinal vesicle–stage (GV) oocytes are divided into two major types, NSN (non-surrounded nucleolus) and SN (surrounded nucleolus), and at least one intermediate type, pSN (partly surrounded nucleolus), based on large-scale chromatin configuration. In mice, the SN oocytes are considered to be the most meiotically competent, which explains active study of their phenotypic characteristics necessary for improvement of human reproductive technologies. One of such characteristics is the position of the GV (nucleus) relative to the center of the oocyte. However, the current data on this issue are contradictory and even completely absent for pSN oocytes. In this work, we have studied the GV position in 187 mouse GV oocytes belonging to NSN, SN, and pSN types using different approaches known from the literature. Our results suggest that (1) the most abundant in all examined types of oocytes are central GVs (43– 66%) and the least abundant are peripheral GVs (12–39%); the pSN oocytes are closer to SN oocytes rather than to NSN oocytes according to the GV position; (3) the position of the nucleus in mouse GV oocytes is an ambiguous marker of large-scale chromatin configuration and, correspondingly, maturation competence of the oocyte; (4) the diversity of the GV position in NSN, SN, and pSN oocytes most likely reflects the ability of GVs to migrate; and (5) assessment of the GV position according to three variants (central, peripheral, and intermediate) is more informative as compared with two variants (central and peripheral).

Large-scale configuration interaction description of the structure of nuclei around 100Sn and 208Pb

In this contribution I would like to discuss briefly the recent developments of the nuclear configuration interaction shell model approach. As examples, we apply the model to calculate the structure and decay properties of low-lying states in neutron-deficient nuclei around 100Sn and 208Pb that are of great experimental and theoretical interests.

ELECTRON ACCELERATION AT A CORONAL SHOCK PROPAGATING THROUGH A LARGE-SCALE STREAMER-LIKE MAGNETIC FIELD

ABSTRACT Using a test-particle simulation, we investigate the effect of large-scale coronal magnetic fields on electron acceleration at an outward-propagating coronal shock with a circular front. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featuring a partially open magnetic field and a current sheet at the equator atop the closed region. We show that the large-scale shock-field configuration, especially the relative curvature of the shock and the magnetic field line across which the shock is sweeping, plays an important role in the efficiency of electron acceleration. At low shock altitudes, when the shock curvature is larger than that of the magnetic field lines, the electrons are mainly accelerated at the shock flanks; at higher altitudes, when the shock curvature is smaller, the electrons are mainly accelerated at the shock nose around the top of closed field lines. The above process reveals the shift of the efficient electron acceleration region along the shock front during its propagation. We also find that, in general, the electron acceleration at the shock flank is not as efficient as that at the top of the closed field because a collapsing magnetic trap can be formed at the top. In addition, we find that the energy spectra of electrons are power-law-like, first hardening then softening with the spectral index varying in a range of −3 to −6. Physical interpretations of the results and implications for the study of solar radio bursts are discussed.

Data on morphology, large-scale chromatin configuration and the occurrence of proteins and rRNA in nucleolus-like bodies of fully-grown mouse oocytes in different fixatives.

Here we provide data on accessibility of nucleolus-like bodies (NLBs) of fully-grown (GV) mouse oocytes to fluorescence in situ hybridization (FISH) probes and anti-nucleolar antibodies as well as on oocyte general morphology and large scale chromatin configuration, which relate to the research article “High-resolution microscopy of active ribosomal genes and key members of the rRNA processing machinery inside nucleolus-like bodies of fully-grown mouse oocytes” (Shishova et al., 2015 [1]). Experimental factors include: a cross-linking reagent formaldehyde and two denaturing fixatives, such as 70% ethanol and a mixture of absolute methanol and glacial acetic acid (3:1, v/v).

MICROWAVE IMAGING OF A HOT FLUX ROPE STRUCTURE DURING THE PRE-IMPULSIVE STAGE OF AN ERUPTIVE M7.7 SOLAR FLARE

ABSTRACT Corona structures and processes during the pre-impulsive stage of solar eruption are crucial to understanding the physics leading to the subsequent explosive energy release. Here we present the first microwave imaging study of a hot flux rope structure during the pre-impulsive stage of an eruptive M7.7 solar flare, with the Nobeyama Radioheliograph at 17 GHz. The flux rope is also observed by the SDO/AIA in its hot passbands of 94 and 131 Å. In the microwave data, it is revealed as an overall arcade-like structure consisting of several intensity enhancements bridged by generally weak emissions, with brightness temperatures (T B) varying from ∼10,000 K to ∼20,000 K. Locations of microwave intensity enhancements along the structure remain relatively fixed at certain specific parts of the flux rope, indicating that the distribution of emitting electrons is affected by the large-scale magnetic configuration of the twisted flux rope. Wavelet analysis shows a pronounced 2 minute period of the microwave T B variation during the pre-impulsive stage of interest. The period agrees well with that reported for AIA sunward-contracting loops and upward ejective plasmoids (suggested to be reconnection outflows). This suggests that both periodicities are controlled by the same reconnection process that takes place intermittently at a 2 minute timescale. We infer that at least a part of the emission is excited by non-thermal energetic electrons via the gyro-synchrotron mechanism. The study demonstrates the potential of microwave imaging in exploring the flux rope magnetic geometry and relevant reconnection process during the onset of solar eruption.