McCarthy, Shane P; Thakkar, Ajit J
2011-01-28
All-electron correlation energies E(c) are not very well-known for atoms with more than 18 electrons. Hence, coupled-cluster calculations in carefully designed basis sets are combined with fully converged second-order Møller-Plesset perturbation theory (MP2) computations to obtain fairly accurate, nonrelativistic E(c) values for the 12 closed-shell atoms from Ar to Rn. These energies will be useful for the evaluation and parameterization of density functionals. The results show that MP2 overestimates ∣E(c)∣ for heavy atoms. Spin-component scaling of the MP2 correlation energy is used to provide a simple explanation for this overestimation.
NASA Astrophysics Data System (ADS)
Stanke, Monika; Palikot, Ewa; KÈ©dziera, Dariusz; Adamowicz, Ludwik
2016-12-01
An algorithm for calculating the first-order electronic orbit-orbit magnetic interaction correction for an electronic wave function expanded in terms of all-electron explicitly correlated molecular Gaussian (ECG) functions with shifted centers is derived and implemented. The algorithm is tested in calculations concerning the H2 molecule. It is also applied in calculations for LiH and H3+ molecular systems. The implementation completes our work on the leading relativistic correction for ECGs and paves the way for very accurate ECG calculations of ground and excited potential energy surfaces (PESs) of small molecules with two and more nuclei and two and more electrons, such as HeH-, H3+, HeH2, and LiH2+. The PESs will be used to determine rovibrational spectra of the systems.
Ab initio GW quasiparticle energies of small sodium clusters by an all-electron mixed-basis approach
NASA Astrophysics Data System (ADS)
Ishii, Soh; Ohno, Kaoru; Kawazoe, Yoshiyuki; Louie, Steven G.
2001-04-01
A state-of-the-art GW calculation is carried out for small sodium clusters, Na2, Na4, Na6, and Na8. The quasiparticle energies are evaluated by employing an ab initio GW code based on an all-electron mixed-basis approach, which uses both plane waves and atomic orbitals as basis functions. The calculated ionization potential and the electron affinity are in excellent agreement with available experimental data. The exchange and correlation parts to the electron self-energy within the GW approximation are presented from the viewpoint of their size dependence. In addition, the effect of the off-diagonal elements of the self-energy corrections to the local-density-approximation exchange-correlation potential is discussed. Na2 and Na8 have a larger energy gap than Na4 and Na6, consistent with the fact that they are magic number clusters.
NASA Astrophysics Data System (ADS)
Stanke, Monika; Jurkowski, Jacek; Adamowicz, Ludwik
2017-03-01
Algorithms for calculating the quantum electrodynamics Araki–Sucher correction for n-electron explicitly correlated molecular Gaussian functions with shifted centers are derived and implemented. The algorithms are tested in calculations concerning the H2 molecule and applied in ground-state calculations of LiH and {{{H}}}3+ molecules. The implementation will significantly increase the accuracy of the calculations of potential energy surfaces of small diatomic and triatomic molecules and their rovibrational spectra.
NASA Astrophysics Data System (ADS)
Knuth, Franz; Carbogno, Christian; Atalla, Viktor; Blum, Volker; Scheffler, Matthias
2015-05-01
We derive and implement the strain derivatives of the total energy of solids, i.e., the analytic stress tensor components, in an all-electron, numeric atom-centered orbital based density-functional formalism. We account for contributions that arise in the semi-local approximation (LDA/GGA) as well as in the generalized Kohn-Sham case, in which a fraction of exact exchange (hybrid functionals) is included. In this work, we discuss the details of the implementation including the numerical corrections for sparse integrations grids which allow to produce accurate results. We validate the implementation for a variety of test cases by comparing to strain derivatives performed via finite differences. Additionally, we include the detailed definition of the overlapping atom-centered integration formalism used in this work to obtain total energies and their derivatives.
NASA Astrophysics Data System (ADS)
Losilla, S. A.; Sundholm, D.
2012-06-01
A computational scheme to perform accurate numerical calculations of electrostatic potentials and interaction energies for molecular systems has been developed and implemented. Molecular electron and energy densities are divided into overlapping atom-centered atomic contributions and a three-dimensional molecular remainder. The steep nuclear cusps are included in the atom-centered functions making the three-dimensional remainder smooth enough to be accurately represented with a tractable amount of grid points. The one-dimensional radial functions of the atom-centered contributions as well as the three-dimensional remainder are expanded using finite element functions. The electrostatic potential is calculated by integrating the Coulomb potential for each separate density contribution, using our tensorial finite element method for the three-dimensional remainder. We also provide algorithms to compute accurate electron-electron and electron-nuclear interactions numerically using the proposed partitioning. The methods have been tested on all-electron densities of 18 reasonable large molecules containing elements up to Zn. The accuracy of the calculated Coulomb interaction energies is in the range of 10-3 to 10-6 Eh when using an equidistant grid with a step length of 0.05 a0.
NASA Astrophysics Data System (ADS)
Blum, Volker
This talk describes recent advances of a general, efficient, accurate all-electron electronic theory approach based on numeric atom-centered orbitals; emphasis is placed on developments related to materials for energy conversion and their discovery. For total energies and electron band structures, we show that the overall accuracy is on par with the best benchmark quality codes for materials, but scalable to large system sizes (1,000s of atoms) and amenable to both periodic and non-periodic simulations. A recent localized resolution-of-identity approach for the Coulomb operator enables O (N) hybrid functional based descriptions of the electronic structure of non-periodic and periodic systems, shown for supercell sizes up to 1,000 atoms; the same approach yields accurate results for many-body perturbation theory as well. For molecular systems, we also show how many-body perturbation theory for charged and neutral quasiparticle excitation energies can be efficiently yet accurately applied using basis sets of computationally manageable size. Finally, the talk highlights applications to the electronic structure of hybrid organic-inorganic perovskite materials, as well as to graphene-based substrates for possible future transition metal compound based electrocatalyst materials. All methods described here are part of the FHI-aims code. VB gratefully acknowledges contributions by numerous collaborators at Duke University, Fritz Haber Institute Berlin, TU Munich, USTC Hefei, Aalto University, and many others around the globe.
NASA Astrophysics Data System (ADS)
Amador, Davi H. T.; de Oliveira, Heibbe C. B.; Sambrano, Julio R.; Gargano, Ricardo; de Macedo, Luiz Guilherme M.
2016-10-01
A prolapse-free basis set for Eka-Actinium (E121, Z = 121), numerical atomic calculations on E121, spectroscopic constants and accurate analytical form for the potential energy curve of diatomic E121F obtained at 4-component all-electron CCSD(T) level including Gaunt interaction are presented. The results show a strong and polarized bond (≈181 kcal/mol in strength) between E121 and F, the outermost frontier molecular orbitals from E121F should be fairly similar to the ones from AcF and there is no evidence of break of periodic trends. Moreover, the Gaunt interaction, although small, is expected to influence considerably the overall rovibrational spectra.
NASA Astrophysics Data System (ADS)
Malli, Gulzari L.; Siegert, Martin; Turner, David P.
All-electron all-virtual spinor space (AVSS) relativistic second order Møller-Plesset (RMP2), coupled-cluster singles doubles (RCCSD), RCCSD(T) (RCCSD plus the triple excitation correction included perturbationally) calculations are reported for tetrahedral (Td) PbH4 at various bond lengths using our finite contracted universal Gaussian basis set. Our relativistic calculations predict the RMP2, RCCSD, and RCCD(T) molecular correlation energy for PbH4 as -2.2563, -2.1917, and -2.2311 au, respectively. Ours are the first AVSS RMP2, RCCSD, and RCCSD(T) molecular calculations for electron correlation energy of the heavy element molecule PbH4. All-electron AVSS coupled-cluster calculations for the Pb atom are also reported and these were used (in conjunction with the corresponding molecular electron correlation energy calculations for PbH4) to predict atomization energy (Ae) of PbH4 at various levels of coupled-cluster electron correlation. Our predicted atomization energy for PbH4 (at the optimized bond length of 1.749 Å) with our Dirac-Fock, RMP2, RCCSD, and RCCSD(T) calculations is 5.73, 7.27, 11.24, and 11.62 eV, respectively. Neither such relativistic molecular correlation energy nor atomization energy has been reported so far for heavy polyatomic with 86 electrons. Calculation of relativistic molecular correlation energy is no more a nightmare, and bottlenecks are broken for the calculation of relativistic correlation as well as atomization energy for molecules of heavy elements.
Sharkey, Keeper L; Adamowicz, Ludwik
2014-05-07
An algorithm for quantum-mechanical nonrelativistic variational calculations of L = 0 and M = 0 states of atoms with an arbitrary number of s electrons and with three p electrons have been implemented and tested in the calculations of the ground (4)S state of the nitrogen atom. The spatial part of the wave function is expanded in terms of all-electrons explicitly correlated Gaussian functions with the appropriate pre-exponential Cartesian angular factors for states with the L = 0 and M = 0 symmetry. The algorithm includes formulas for calculating the Hamiltonian and overlap matrix elements, as well as formulas for calculating the analytic energy gradient determined with respect to the Gaussian exponential parameters. The gradient is used in the variational optimization of these parameters. The Hamiltonian used in the approach is obtained by rigorously separating the center-of-mass motion from the laboratory-frame all-particle Hamiltonian, and thus it explicitly depends on the finite mass of the nucleus. With that, the mass effect on the total ground-state energy is determined.
Sharkey, Keeper L.; Adamowicz, Ludwik
2014-05-07
An algorithm for quantum-mechanical nonrelativistic variational calculations of L = 0 and M = 0 states of atoms with an arbitrary number of s electrons and with three p electrons have been implemented and tested in the calculations of the ground {sup 4}S state of the nitrogen atom. The spatial part of the wave function is expanded in terms of all-electrons explicitly correlated Gaussian functions with the appropriate pre-exponential Cartesian angular factors for states with the L = 0 and M = 0 symmetry. The algorithm includes formulas for calculating the Hamiltonian and overlap matrix elements, as well as formulas for calculating the analytic energy gradient determined with respect to the Gaussian exponential parameters. The gradient is used in the variational optimization of these parameters. The Hamiltonian used in the approach is obtained by rigorously separating the center-of-mass motion from the laboratory-frame all-particle Hamiltonian, and thus it explicitly depends on the finite mass of the nucleus. With that, the mass effect on the total ground-state energy is determined.
Basis set limit and systematic errors in local-orbital based all-electron DFT
NASA Astrophysics Data System (ADS)
Blum, Volker; Behler, Jörg; Gehrke, Ralf; Reuter, Karsten; Scheffler, Matthias
2006-03-01
With the advent of efficient integration schemes,^1,2 numeric atom-centered orbitals (NAO's) are an attractive basis choice in practical density functional theory (DFT) calculations of nanostructured systems (surfaces, clusters, molecules). Though all-electron, the efficiency of practical implementations promises to be on par with the best plane-wave pseudopotential codes, while having a noticeably higher accuracy if required: Minimal-sized effective tight-binding like calculations and chemically accurate all-electron calculations are both possible within the same framework; non-periodic and periodic systems can be treated on equal footing; and the localized nature of the basis allows in principle for O(N)-like scaling. However, converging an observable with respect to the basis set is less straightforward than with competing systematic basis choices (e.g., plane waves). We here investigate the basis set limit of optimized NAO basis sets in all-electron calculations, using as examples small molecules and clusters (N2, Cu2, Cu4, Cu10). meV-level total energy convergence is possible using <=50 basis functions per atom in all cases. We also find a clear correlation between the errors which arise from underconverged basis sets, and the system geometry (interatomic distance). ^1 B. Delley, J. Chem. Phys. 92, 508 (1990), ^2 J.M. Soler et al., J. Phys.: Condens. Matter 14, 2745 (2002).
Improved Segmented All-Electron Relativistically Contracted Basis Sets for the Lanthanides.
Aravena, Daniel; Neese, Frank; Pantazis, Dimitrios A
2016-03-08
Improved versions of the segmented all-electron relativistically contracted (SARC) basis sets for the lanthanides are presented. The second-generation SARC2 basis sets maintain efficient construction of their predecessors and their individual adaptation to the DKH2 and ZORA Hamiltonians, but feature exponents optimized with a completely new orbital shape fitting procedure and a slightly expanded f space that results in sizable improvement in CASSCF energies and in significantly more accurate prediction of spin-orbit coupling parameters. Additionally, an extended set of polarization/correlation functions is constructed that is appropriate for multireference correlated calculations and new auxiliary basis sets for use in resolution-of-identity (density-fitting) approximations in combination with both DFT and wave function based treatments. Thus, the SARC2 basis sets extend the applicability of the first-generation DFT-oriented basis sets to routine all-electron wave function-based treatments of lanthanide complexes. The new basis sets are benchmarked with respect to excitation energies, radial distribution functions, optimized geometries, orbital eigenvalues, ionization potentials, and spin-orbit coupling parameters of lanthanide systems and are shown to be suitable for the description of magnetic and spectroscopic properties using both DFT and multireference wave function-based methods.
Angular correlations and high energy evolution
Kovner, Alex; Lublinsky, Michael
2011-11-01
We address the question of to what extent JIMWLK evolution is capable of taking into account angular correlations in a high energy hadronic wave function. Our conclusion is that angular (and indeed other) correlations in the wave function cannot be reliably calculated without taking into account Pomeron loops in the evolution. As an example we study numerically the energy evolution of angular correlations between dipole scattering amplitudes in the framework of the large N{sub c} approximation to JIMWLK evolution (the 'projectile dipole model'). Target correlations are introduced via averaging over an (isotropic) ensemble of anisotropic initial conditions. We find that correlations disappear very quickly with rapidity even inside the saturation radius. This is in accordance with our physical picture of JIMWLK evolution. The actual correlations inside the saturation radius in the target QCD wave function, on the other hand, should remain sizable at any rapidity.
NASA Technical Reports Server (NTRS)
Dyall, Kenneth G.
1992-01-01
Relativistic corrections to a number of properties of the Group IV hydrides are calculated using the Dirac-Hartree-Fock method. The use of first-order perturbation theory is sufficient to obtain relativistic corrections for Ge, but the effects of spin-orbit interaction and other higher-order effects begin to show for Sn and become important for Pb. The energy of the reaction XH4 yields XH2 + H2 (X = Si, Ge, Sn, and Pb) is also calculated. The results are compared with relativistic effective core potential calculations, first-order perturbation theory calculations, and limited experimental data.
Angular correlations near the Fermi energy
Fox, D.; Cebra, D.A.; Karn, J.; Parks, C.; Pradhan, A.; Vander Molen, A.; van der Plicht, J.; Westfall, G.D.; Wilson, W.K.; Tickle, R.S.; and others
1988-07-01
Angular correlations between light particles have been studied to probe the extent to which a thermally equilibrated system is formed in heavy ion collisions near the Fermi energy. Single-light-particle inclusive energy spectra and two-particle large-angle correlations were measured for 40 and 50 MeV/nucleon C+C, Ag, and Au. The single-particle inclusive energy spectra are well fit by a three moving source parametrization. Two-particle large-angle correlations are shown to be consistent with emission from a thermally equilibrated source when the effects of momentum conservation are considered. Single-particle inclusive spectra and light-particle correlations at small relative momentum were measured for 35 MeV/nucleon N+Ag. Source radii were extracted from the two-particle correlation functions and were found to be consistent with previous measurements using two-particle correlations and the coalescence model. The temperature of the emitting source was extracted from the relative populations of states using the quantum statistical model and was found to be 4.8/sub -2.4//sup +2.8/ MeV, compared to the 14 MeV temperature extracted from the slopes of the kinetic energy spectra.
Self-consistent GW: All-electron implementation with localized basis functions
NASA Astrophysics Data System (ADS)
Caruso, Fabio; Rinke, Patrick; Ren, Xinguo; Rubio, Angel; Scheffler, Matthias
2013-08-01
This paper describes an all-electron implementation of the self-consistent GW (sc-GW) approach—i.e., based on the solution of the Dyson equation—in an all-electron numeric atom-centered orbital basis set. We cast Hedin's equations into a matrix form that is suitable for numerical calculations by means of (i) the resolution-of-identity technique to handle four-center integrals and (ii) a basis representation for the imaginary-frequency dependence of dynamical operators. In contrast to perturbative G0W0, sc-GW provides a consistent framework for ground- and excited-state properties and facilitates an unbiased assessment of the GW approximation. For excited states, we benchmark sc-GW for five molecules relevant for organic photovoltaic applications: thiophene, benzothiazole, 1,2,5-thiadiazole, naphthalene, and tetrathiafulvalene. At self-consistency, the quasiparticle energies are found to be in good agreement with experiment and, on average, more accurate than G0W0 based on Hartree-Fock or density-functional theory with the Perdew-Burke-Ernzerhof exchange-correlation functional. Based on the Galitskii-Migdal total energy, structural properties are investigated for a set of diatomic molecules. For binding energies, bond lengths, and vibrational frequencies sc-GW and G0W0 achieve a comparable performance, which is, however, not as good as that of exact-exchange plus correlation in the random-phase approximation and its advancement to renormalized second-order perturbation theory. Finally, the improved description of dipole moments for a small set of diatomic molecules demonstrates the quality of the sc-GW ground-state density.
Nondynamical correlation energy in model molecular systems
NASA Astrophysics Data System (ADS)
Chojnacki, Henryk
The hypersurfaces for the deprotonation processes have been studied at the nonempirical level for H3O+, NH+4, PH+4, and H3S+ cations within their correlation consistent basis set. The potential energy curves were calculated and nondynamical correlation energies analyzed. We have found that the restricted Hartree-Fock wavefunction leads to the improper dissociation limit and, in the three latest cases requires multireference description. We conclude that these systems may be treated as a good models for interpretation of the proton transfer mechanism as well as for testing one-determinantal or multireference cases.
Electronic correlation contributions to structural energies
NASA Astrophysics Data System (ADS)
Haydock, Roger
2015-03-01
The recursion method is used to calculate electronic excitation spectra including electron-electron interactions within the Hubbard model. The effects of correlation on structural energies are then obtained from these spectra and applied to stacking faults. http://arxiv.org/abs/1405.2288 Supported by the Richmond F. Snyder Fund and Gifts.
Energy and Angular Correlations of Fission Products
NASA Astrophysics Data System (ADS)
Peters, William; Smith, M. S.; Pain, S. D.; Febbraro, M.; Galindo-Uribarri, A.; Jones, K. L.; Smith, K.; Grzywacz, R.; Temanson, E.; Cizewski, J. A.
2016-09-01
Despite the discovery of fission nearly 80 years ago and its importance to nuclear energy, national security, and astrophysics; there are very few measurements that correlate multiple fission products. A proof-of-principle experiment is underway at Oak Ridge National Lab to measure the energy and angle correlation between prompt fission neutrons, gamma rays, and fragments in time-coincidence. The angular and energy spectrum of the prompt neutrons and /or gamma rays with respect to fragment mass, could reveal new details concerning the energy balance between these products and will be essential for benchmarking advanced fission models. An array of neutron and gamma-ray detectors is positioned opposite dual time-of-flight detectors and a total-energy detector to determine one fragment mass. Preliminary results from a spontaneous 252Cf source will be presented, along with plans for future improvements. Research sponsored in part by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.
Long-range correlation energy calculated from coupled atomic response functions
Ambrosetti, Alberto; Reilly, Anthony M.; Tkatchenko, Alexandre; DiStasio, Robert A.
2014-05-14
An accurate determination of the electron correlation energy is an essential prerequisite for describing the structure, stability, and function in a wide variety of systems. Therefore, the development of efficient approaches for the calculation of the correlation energy (and hence the dispersion energy as well) is essential and such methods can be coupled with many density-functional approximations, local methods for the electron correlation energy, and even interatomic force fields. In this work, we build upon the previously developed many-body dispersion (MBD) framework, which is intimately linked to the random-phase approximation for the correlation energy. We separate the correlation energy into short-range contributions that are modeled by semi-local functionals and long-range contributions that are calculated by mapping the complex all-electron problem onto a set of atomic response functions coupled in the dipole approximation. We propose an effective range-separation of the coupling between the atomic response functions that extends the already broad applicability of the MBD method to non-metallic materials with highly anisotropic responses, such as layered nanostructures. Application to a variety of high-quality benchmark datasets illustrates the accuracy and applicability of the improved MBD approach, which offers the prospect of first-principles modeling of large structurally complex systems with an accurate description of the long-range correlation energy.
New angles on energy correlation functions
NASA Astrophysics Data System (ADS)
Moult, Ian; Necib, Lina; Thaler, Jesse
2016-12-01
Jet substructure observables, designed to identify specific features within jets, play an essential role at the Large Hadron Collider (LHC), both for searching for signals beyond the Standard Model and for testing QCD in extreme phase space regions. In this paper, we systematically study the structure of infrared and collinear safe substructure observables, defining a generalization of the energy correlation functions to probe n-particle correlations within a jet. These generalized correlators provide a flexible basis for constructing new substructure observables optimized for specific purposes. Focusing on three major targets of the jet substructure community — boosted top tagging, boosted W/Z/H tagging, and quark/gluon discrimination — we use power-counting techniques to identify three new series of powerful discriminants: M i , N i , and U i . The M i series is designed for use on groomed jets, providing a novel example of observables with improved discrimination power after the removal of soft radiation. The N i series behave parametrically like the N -subjettiness ratio observables, but are defined without respect to subjet axes, exhibiting improved behavior in the unresolved limit. Finally, the U i series improves quark/gluon discrimination by using higher-point correlators to simultaneously probe multiple emissions within a jet. Taken together, these observables broaden the scope for jet substructure studies at the LHC.
ERP Energy and Cognitive Activity Correlates
NASA Astrophysics Data System (ADS)
Schillaci, Michael Jay; Vendemia, Jennifer M. C.
2014-03-01
We propose a novel analysis approach for high-density event related scalp potential (ERP) data where the integrated channel-power is used to attain an energy density functional state for channel-clusters of neurophysiological significance. The method is applied to data recorded during a two-stimulus, directed lie paradigm and shows that deceptive responses emit between 8% and 10% less power. A time course analysis of these cognitive activity measures over posterior and anterior regions of the cortex suggests that neocortical interactions, reflecting the differing workload demands during executive and semantic processes, take about 50% longer for the case of deception. These results suggest that the proposed method may provide a useful tool for the analysis of ERP correlates of high-order cognitive functioning. We also report on a possible equivalence between the energy functional distribution and near-infrared signatures that have been measured with other modalities.
Correlation Energy of A Model Problem
NASA Astrophysics Data System (ADS)
Campuzano, Mauricio; Fessatidis, Vassilios; Mancini, Jay D.; Bowen, Samuel P.
2006-03-01
The search for new analytic methods of calculating details of the energy spectrum of strongly interacting systems has long been the vocation of both theoretical chemists and physicists. In particular, the accurate calculation of both the ground-state and correlation energies are important in settling issues relating to the exact nature of the ground-state and low-lying excited states. Furthermore there exist a number of physically relevant systems that cannot be treated by perturbation theory or in which other approximation schemes yield completely erroneous results. Exact diagonalization studies are well known to suffer from size effects, while the neglection of correlations in fluctuations in mean-field theories, although calculationally tractable, leave much to be desired. Here we wish to apply a recently developed Generalized Moments Expansion (GMX) [1] to the problem of N coupled one dimensional harmonic oscillators given by the Hamiltonian: H=12∑j=1^N( -d^2dxj^2+2circ % xj^2) +g^2∑ij^Nxij. Comparisons are then made with other methods such as a Lanczos tridiagonalization scheme as well as a Canonical Sequence Method approach. 1] V. Fessatidis, J.D. Mancini, R. Murawski and S.P. Bowen, Phys. Lett. A.
Optical properties of alkali halide crystals from all-electron hybrid TD-DFT calculations
Webster, R. Harrison, N. M.; Bernasconi, L.
2015-06-07
We present a study of the electronic and optical properties of a series of alkali halide crystals AX, with A = Li, Na, K, Rb and X = F, Cl, Br based on a recent implementation of hybrid-exchange time-dependent density functional theory (TD-DFT) (TD-B3LYP) in the all-electron Gaussian basis set code CRYSTAL. We examine, in particular, the impact of basis set size and quality on the prediction of the optical gap and exciton binding energy. The formation of bound excitons by photoexcitation is observed in all the studied systems and this is shown to be correlated to specific features of the Hartree-Fock exchange component of the TD-DFT response kernel. All computed optical gaps and exciton binding energies are however markedly below estimated experimental and, where available, 2-particle Green’s function (GW-Bethe-Salpeter equation, GW-BSE) values. We attribute this reduced exciton binding to the incorrect asymptotics of the B3LYP exchange correlation ground state functional and of the TD-B3LYP response kernel, which lead to a large underestimation of the Coulomb interaction between the excited electron and hole wavefunctions. Considering LiF as an example, we correlate the asymptotic behaviour of the TD-B3LYP kernel to the fraction of Fock exchange admixed in the ground state functional c{sub HF} and show that there exists one value of c{sub HF} (∼0.32) that reproduces at least semi-quantitatively the optical gap of this material.
Optical properties of alkali halide crystals from all-electron hybrid TD-DFT calculations.
Webster, R; Bernasconi, L; Harrison, N M
2015-06-07
We present a study of the electronic and optical properties of a series of alkali halide crystals AX, with A = Li, Na, K, Rb and X = F, Cl, Br based on a recent implementation of hybrid-exchange time-dependent density functional theory (TD-DFT) (TD-B3LYP) in the all-electron Gaussian basis set code CRYSTAL. We examine, in particular, the impact of basis set size and quality on the prediction of the optical gap and exciton binding energy. The formation of bound excitons by photoexcitation is observed in all the studied systems and this is shown to be correlated to specific features of the Hartree-Fock exchange component of the TD-DFT response kernel. All computed optical gaps and exciton binding energies are however markedly below estimated experimental and, where available, 2-particle Green's function (GW-Bethe-Salpeter equation, GW-BSE) values. We attribute this reduced exciton binding to the incorrect asymptotics of the B3LYP exchange correlation ground state functional and of the TD-B3LYP response kernel, which lead to a large underestimation of the Coulomb interaction between the excited electron and hole wavefunctions. Considering LiF as an example, we correlate the asymptotic behaviour of the TD-B3LYP kernel to the fraction of Fock exchange admixed in the ground state functional cHF and show that there exists one value of cHF (∼0.32) that reproduces at least semi-quantitatively the optical gap of this material.
Optical properties of alkali halide crystals from all-electron hybrid TD-DFT calculations
NASA Astrophysics Data System (ADS)
Webster, R.; Bernasconi, L.; Harrison, N. M.
2015-06-01
We present a study of the electronic and optical properties of a series of alkali halide crystals AX, with A = Li, Na, K, Rb and X = F, Cl, Br based on a recent implementation of hybrid-exchange time-dependent density functional theory (TD-DFT) (TD-B3LYP) in the all-electron Gaussian basis set code CRYSTAL. We examine, in particular, the impact of basis set size and quality on the prediction of the optical gap and exciton binding energy. The formation of bound excitons by photoexcitation is observed in all the studied systems and this is shown to be correlated to specific features of the Hartree-Fock exchange component of the TD-DFT response kernel. All computed optical gaps and exciton binding energies are however markedly below estimated experimental and, where available, 2-particle Green's function (GW-Bethe-Salpeter equation, GW-BSE) values. We attribute this reduced exciton binding to the incorrect asymptotics of the B3LYP exchange correlation ground state functional and of the TD-B3LYP response kernel, which lead to a large underestimation of the Coulomb interaction between the excited electron and hole wavefunctions. Considering LiF as an example, we correlate the asymptotic behaviour of the TD-B3LYP kernel to the fraction of Fock exchange admixed in the ground state functional cHF and show that there exists one value of cHF (˜0.32) that reproduces at least semi-quantitatively the optical gap of this material.
Correlation energy of anisotropic quantum dots
Zhao Yan; Loos, Pierre-Francois; Gill, Peter M. W.
2011-09-15
We study the D-dimensional high-density correlation energy E{sub c} of the singlet ground state of two electrons confined by a harmonic potential with Coulombic repulsion. We allow the harmonic potential to be anisotropic and examine the behavior of E{sub c} as a function of the anisotropy {alpha}{sup -1}. In particular, we are interested in the limit where the anisotropy goes to infinity ({alpha}{yields}0) and the electrons are restricted to a lower-dimensional space. We show that tuning the value of {alpha} from 0 to 1 allows a smooth dimensional interpolation and we demonstrate that the usual model, in which a quantum dot is treated as a two-dimensional system, is inappropriate. Finally, we provide a simple function which reproduces the behavior of E{sub c} over the entire range of {alpha}.
NASA Astrophysics Data System (ADS)
McDonagh, James L.; Vincent, Mark A.; Popelier, Paul L. A.
2016-10-01
Here MP2, MP3 and MP4(SDQ) are energy-partitioned for the first time within the Interacting Quantum Atoms (IQA) context, as proof-of-concept for H2, He2 and HF. Energies are decomposed into four primary energy contributions: (i) atomic self-energies, and atomic interaction energies comprising of (ii) Coulomb, (iii) exchange and (iv) dynamic election correlation terms. We generate and partition one- and two-particle density-matrices to obtain all atomic energy components. This work suggests that, in terms of Van der Waals dispersion, the correlation energies represent an atomic stabilisation, by proximity to other atoms, as opposed to direct interactions with other nearby atoms.
Gas-Liquid Correlation of Ionization Energies.
1984-04-01
ions and water. The threshold and reorganization energies of the hydrated electron are calculated from threshold energies of anions and their absorption...hydroxide ions and water. The threshold and reorganization energies of the hydrated electron are calculated from threshold energies of anions and their...threshold energy of the hydrated electron. 2. Free energy of emission and gas-phase ionization Consider the photoelectron emission by an aqueous
Rapid Bacterial Detection via an All-Electronic CMOS Biosensor
Nikkhoo, Nasim; Cumby, Nichole; Gulak, P. Glenn; Maxwell, Karen L.
2016-01-01
The timely and accurate diagnosis of infectious diseases is one of the greatest challenges currently facing modern medicine. The development of innovative techniques for the rapid and accurate identification of bacterial pathogens in point-of-care facilities using low-cost, portable instruments is essential. We have developed a novel all-electronic biosensor that is able to identify bacteria in less than ten minutes. This technology exploits bacteriocins, protein toxins naturally produced by bacteria, as the selective biological detection element. The bacteriocins are integrated with an array of potassium-selective sensors in Complementary Metal Oxide Semiconductor technology to provide an inexpensive bacterial biosensor. An electronic platform connects the CMOS sensor to a computer for processing and real-time visualization. We have used this technology to successfully identify both Gram-positive and Gram-negative bacteria commonly found in human infections. PMID:27618185
NASA Technical Reports Server (NTRS)
Deng, Yue
2014-01-01
Describes solar energy inputs contributing to ionospheric and thermospheric weather processes, including total energy amounts, distributions and the correlation between particle precipitation and Poynting flux.
Electrostatic correlations and the polyelectrolyte self energy.
Shen, Kevin; Wang, Zhen-Gang
2017-02-28
We address the effects of chain connectivity on electrostaticfluctuations in polyelectrolyte solutions using a field-theoretic, renormalizedGaussian fluctuation (RGF) theory. As in simple electrolyte solutions [Z.-G. Wang,Phys. Rev. E 81, 021501 (2010)], the RGF provides a unified theory forelectrostatic fluctuations, accounting for both dielectric and charge correlationeffects in terms of the self-energy. Unlike simple ions, the polyelectrolyte self energydepends intimately on the chain conformation, and our theory naturally provides aself-consistent determination of the response of intramolecular chain structure topolyelectrolyte and salt concentrations. The effects of the chain-conformation on theself-energy and thermodynamics are especially pronounced for flexiblepolyelectrolytes at low polymer and salt concentrations, where application of thewrong chain structure can lead to a drastic misestimation of the electrostaticcorrelations. By capturing the expected scaling behavior of chain size from dilute tosemi-dilute regimes, our theory provides improved estimates of the self energy at lowpolymer concentrations and correctly predicts the eventual N-independenceof the critical temperature and concentration of salt-free solutions of flexiblepolyelectrolytes. We show that the self energy can be interpreted in terms of aninfinite-dilution energy μm,0(el) and a finite concentrationcorrelation correction μ(corr) which tends to cancel out the formerwith increasing concentration.
Electrostatic correlations and the polyelectrolyte self energy
NASA Astrophysics Data System (ADS)
Shen, Kevin; Wang, Zhen-Gang
2017-02-01
We address the effects of chain connectivity on electrostaticfluctuations in polyelectrolyte solutions using a field-theoretic, renormalizedGaussian fluctuation (RGF) theory. As in simple electrolyte solutions [Z.-G. Wang,Phys. Rev. E 81, 021501 (2010)], the RGF provides a unified theory forelectrostatic fluctuations, accounting for both dielectric and charge correlationeffects in terms of the self-energy. Unlike simple ions, the polyelectrolyte self energydepends intimately on the chain conformation, and our theory naturally provides aself-consistent determination of the response of intramolecular chain structure topolyelectrolyte and salt concentrations. The effects of the chain-conformation on theself-energy and thermodynamics are especially pronounced for flexiblepolyelectrolytes at low polymer and salt concentrations, where application of thewrong chain structure can lead to a drastic misestimation of the electrostaticcorrelations. By capturing the expected scaling behavior of chain size from dilute tosemi-dilute regimes, our theory provides improved estimates of the self energy at lowpolymer concentrations and correctly predicts the eventual N-independenceof the critical temperature and concentration of salt-free solutions of flexiblepolyelectrolytes. We show that the self energy can be interpreted in terms of aninfinite-dilution energy μm,0 el and a finite concentrationcorrelation correction μcorr which tends to cancel out the formerwith increasing concentration.
Meson production based on the Thomson energy correlation
Aspden, H.
1986-07-01
Attention is drawn to a remarkable energy correlation which uniquely determines the rest-mass energies of all the intermediate particles in the electron-proton energy spectrum. The correlation formula uses a classical expression formulated by J. J. Thomson, which represents the charge of a particle as confined within a sphere of radius 2e/sup 2//3mc/sup 2/.
Label-free all-electronic biosensing in microfluidic systems
NASA Astrophysics Data System (ADS)
Stanton, Michael A.
Label-free, all-electronic detection techniques offer great promise for advancements in medical and biological analysis. Electrical sensing can be used to measure both interfacial and bulk impedance changes in conducting solutions. Electronic sensors produced using standard microfabrication processes are easily integrated into microfluidic systems. Combined with the sensitivity of radiofrequency electrical measurements, this approach offers significant advantages over competing biological sensing methods. Scalable fabrication methods also provide a means of bypassing the prohibitive costs and infrastructure associated with current technologies. We describe the design, development and use of a radiofrequency reflectometer integrated into a microfluidic system towards the specific detection of biologically relevant materials. We developed a detection protocol based on impedimetric changes caused by the binding of antibody/antigen pairs to the sensing region. Here we report the surface chemistry that forms the necessary capture mechanism. Gold-thiol binding was utilized to create an ordered alkane monolayer on the sensor surface. Exposed functional groups target the N-terminus, affixing a protein to the monolayer. The general applicability of this method lends itself to a wide variety of proteins. To demonstrate specificity, commercially available mouse anti- Streptococcus Pneumoniae monoclonal antibody was used to target the full-length recombinant pneumococcal surface protein A, type 2 strain D39 expressed by Streptococcus Pneumoniae. We demonstrate the RF response of the sensor to both the presence of the surface decoration and bound SPn cells in a 1x phosphate buffered saline solution. The combined microfluidic sensor represents a powerful platform for the analysis and detection of cells and biomolecules.
An analysis of the correlation energy contribution to the interaction energy of inert gas dimers.
Snook, Ian; Per, Manolo C; Russo, Salvy P
2008-10-28
An accurate description of electron correlation is essential for the calculation of interaction energies in cases where dispersion energy is a major component, for example, for the rare gas atoms, physisorption on graphite, and graphene-graphene interactions. Such calculations are computationally demanding using supermolecule methods and the energies calculated lack a simple, physical interpretation. Alternatively density functional theories (DFTs) may be used to give an approximate estimate of the correlation energy. However, the physical nature of this DFT estimate of electron correlation energy is not well understood and, in fact, most current DFT methods do not describe dispersion energy at all. Hence, an analysis of the correlation energy contribution to interaction energies where dispersion energy is important is needed. In order to do this we provide an analysis of the correlation energy contribution to the potential energy curves of He(2), Ne(2), and Ar(2) in terms of the Hartree-Fock (HF) interaction term DeltaE(int) (HF), a dispersion energy term E(disp) and an electron correlation term DeltaE(int) (C). DeltaE(int) (C) includes all other correlation energy effects besides E(disp) and is shown to be repulsive, of a similar short range character to, but of smaller magnitude than DeltaE(int) (HF). This analysis was used to develop a theoretical model which gives a very good estimate of the potential energy wells for He(2), Ne(2), Ar(2), HeNe, HeAr, and NeAr.
Effect of critical dimension variation on SAW correlator energy.
Skinner, Jack L.
2005-04-01
The effect of critical dimension (CD) variation and metallization ratio on the efficiency of energy conversion of a surface acoustic wave (SAW) correlator is examined. We find that a 10% variation in the width of finger electrodes predicts only a 1% decrease in the efficiency of energy conversion. Furthermore, our model predicts that a metallization ratio of 0.74 represents an optimum value for energy extraction from the SAW by the interdigitated transducer (IDT).
Correlated energy transfer between two ultracold atomic species
NASA Astrophysics Data System (ADS)
Krönke, Sven; Knörzer, Johannes; Schmelcher, Peter
2015-05-01
We study a single atom as an open quantum system, which is initially prepared in a coherent state of low energy and oscillates in a one-dimensional harmonic trap through an interacting ensemble of NA bosons, held in a displaced trap [arXiv:1410.8676]. The non-equilibrium quantum dynamics of the total system is simulated by means of an ab-initio method, giving us access to all properties of the open system and its finite environment. In this talk, we focus on unraveling the interplay of energy exchange and correlations between the subsystems, which are coupled in such a spatio-temporally localized manner. We show that an inter-species interaction-induced level splitting accelerates the energy transfer between the atomic species for larger NA, which becomes less complete at the same time. System-environment correlations prove to be significant except for times when the excess energy distribution among the subsystems is highly imbalanced. These correlations result in incoherent energy transfer processes, which accelerate the early energy donation of the single atom. By analyzing correlations between intra-subsystem excitations, certain energy transfer channels are shown to be (dis-)favored depending on the instantaneous direction of transfer.
Correlation energy for elementary bosons: Physics of the singularity
Shiau, Shiue-Yuan; Combescot, Monique; Chang, Yia-Chung
2016-04-15
We propose a compact perturbative approach that reveals the physical origin of the singularity occurring in the density dependence of correlation energy: like fermions, elementary bosons have a singular correlation energy which comes from the accumulation, through Feynman “bubble” diagrams, of the same non-zero momentum transfer excitations from the free particle ground state, that is, the Fermi sea for fermions and the Bose–Einstein condensate for bosons. This understanding paves the way toward deriving the correlation energy of composite bosons like atomic dimers and semiconductor excitons, by suggesting Shiva diagrams that have similarity with Feynman “bubble” diagrams, the previous elementary boson approaches, which hide this physics, being inappropriate to do so.
Angular correlations in gluon production at high energy
Kovner, Alex; Lublinsky, Michael
2011-02-01
We present a general, model independent argument demonstrating that gluons produced in high energy hadronic collision are necessarily correlated in rapidity and also in the emission angle. The strength of the correlation depends on the process and on the structure/model of the colliding particles. In particular we argue that it is strongly affected (and underestimated) by factorized approximations frequently used to quantify the effect.
Correlations of Energy Ratios for Collective Nuclear Bands
NASA Astrophysics Data System (ADS)
Zamfir, N. V.; Bucurescu, D.; Căta-Danil, G.; Ivaşcu, M.; Mărginean, N.
2009-01-01
It is shown that the Mallmann's energy correlations, introduced a long time ago for the ground state bands of the even-even nuclei are, in fact, universal. Various bands in all collective nuclei (even-even, odd-even, and odd-odd) obey the same systematics. This unique, universal behaviour indicates the same spin dependence of the energy of the levels and, consequently, a common structure of all collective bands. Based on the second-order anharmonic vibrator description, parameter-free recurrence relations between energy ratios are deduced. These relations can be used to predict levels of higher spins in various bands.
Correlations of Energy Ratios for Collective Nuclear Bands
NASA Astrophysics Data System (ADS)
Zamfir, N. V.; Bucurescu, D.; Căta-Danil, G.; Ivaşcu, M.; Mărginean, N.
2009-03-01
It is shown that the Mallmann's energy correlations, introduced a long time ago for the ground state bands of the even-even nuclei are, in fact, universal. Various bands in all collective nuclei (even-even, odd-even, and odd-odd) obey the same systematics. This unique, universal behaviour indicates the same spin dependence of the energy of the levels in all bands in all collective nuclei. Based on a second-order anharmonic vibrator description, parameter-free recurrence relations between energy ratios are deduced. These relations can be used to predict levels of higher spins in various bands.
Correlation energy extrapolation by many-body expansion
Boschen, Jeffery S.; Theis, Daniel; Ruedenberg, Klaus; ...
2017-01-09
Accounting for electron correlation is required for high accuracy calculations of molecular energies. The full configuration interaction (CI) approach can fully capture the electron correlation within a given basis, but it does so at a computational expense that is impractical for all but the smallest chemical systems. In this work, a new methodology is presented to approximate configuration interaction calculations at a reduced computational expense and memory requirement, namely, the correlation energy extrapolation by many-body expansion (CEEMBE). This method combines a MBE approximation of the CI energy with an extrapolated correction obtained from CI calculations using subsets of the virtualmore » orbitals. The extrapolation approach is inspired by, and analogous to, the method of correlation energy extrapolation by intrinsic scaling. Benchmark calculations of the new method are performed on diatomic fluorine and ozone. Finally, the method consistently achieves agreement with CI calculations to within a few mhartree and often achieves agreement to within ~1 millihartree or less, while requiring significantly less computational resources.« less
Electronic correlation in magnetic contributions to structural energies
NASA Astrophysics Data System (ADS)
Haydock, Roger
For interacting electrons the density of transitions [see http://arxiv.org/abs/1405.2288] replaces the density of states in calculations of structural energies. Extending previous work on paramagnetic metals, this approach is applied to correlation effects on the structural stability of magnetic transition metals. Supported by the H. V. Snyder Gift to the University of Oregon.
Near-edge structures from first principles all-electron Bethe-Salpeter equation calculations.
Olovsson, W; Tanaka, I; Puschnig, P; Ambrosch-Draxl, C
2009-03-11
We obtain x-ray absorption near-edge structures (XANES) by solving the equation of motion for the two-particle Green's function for the electron-hole pair, the Bethe-Salpeter equation (BSE), within the all-electron full-potential linearized augmented plane wave method (FPLAPW). The excited states are calculated for the Li K-edge in the insulating solids LiF, Li(2)O and Li(2)S, and absorption spectra are compared with independent particle results using the random phase approximation (RPA), as well as supercell calculations using the core-hole approximation within density functional theory (DFT). The binding energies of strongly bound excitations are determined in the materials, and core-exciton wavefunctions are demonstrated for LiF.
Correlation energy per particle from the coupling-constant integration
Colonna, F.; Maynau, D.; Savin, A.
2003-07-01
The adiabatic connection can be used in density functional theory to define the unknown (exchange and) correlation density functional. Using conventional wave-function techniques, accurate estimates of thus defined (exchange and) correlation energy densities can be obtained for specified systems. In this paper, numerical results are presented for the He and the Be atom, as well as the isoelectron Ne ions. A generalized gradient approximation is tested against these results. The comparison shows that the generalized gradient approximation has the ability to detect local features (the shell structure). In one case (Ne{sup 6+}), however, it turns out that the accurate correlation energy per particle is lower than that obtained within the local-density approximation, and thus not properly corrected by the generalized gradient approximation.
Effect of correlations between minima on a complex energy landscape
NASA Astrophysics Data System (ADS)
Pusuluri, Sai Teja; Lang, Alex H.; Mehta, Pankaj; Castillo, Horacio E.
We recently modeled cellular interconvertion dynamics by using an epigenetic landscape model inspired by neural network models. Given an arbitrary set of patterns, the model can be used to construct an energy landscape in which those patterns are the global minima. We study the possible stable states and metastable states of the landscapes thus constructed. We consider three different cases: i) choosing the patterns to be random and independently distributed ii) choosing a set of patterns directly derived from the experimental cellular transcription factor expression data for a representative set of cell types in an organism and iii) choosing randomly generated trees of hierarchically correlated patterns, inspired by biology. For each of the three cases, we study the energy landscapes. In particular we study the basins of attraction of both the stable states and the metastable states, we compute the configurational entropy as a function of energy, and we demonstrate how those results depend on the correlations between the patterns.
GRB physics and cosmology with peak energy-intensity correlations
NASA Astrophysics Data System (ADS)
Sawant, Disha; Amati, Lorenzo
2015-12-01
Gamma Ray Bursts (GRBs) are immensely energetic explosions radiating up to 1054 erg of energy isotropically (Eiso) and they are observed within a wide range of redshift (from ˜ 0.01 up to ˜ 9). Such enormous power and high redshift point at these phenomena being highly favorable to investigate the history and evolution of our universe. The major obstacle in their application as cosmological study-tools is to find a way to standardize the GRBs, for instance similar to SNe Ia. With respect to this goal, the correlation between spectral peak energy (Ep,i) and the "intensity" is a positively useful and investigated criterion. Moreover, it has been demonstrated that, through the Ep,i - Eiso correlation, the current data set of GRBs can already contribute to the independent evidence of the matter density ΩM being ˜ 0.3 for a flat universe scenario. We try to inspect and compare the correlations of Ep,i with different intensity indicators (e.g., radiated energy, average and peak luminosity, bolometric vs. monochromatic quantities, etc.) both in terms of intrinsic dispersion and precise estimation of ΩM. The outcome of such studies are further analyzed in verifying the reliability of the correlations for both GRB physics and their standardization for cosmology.
GRB physics and cosmology with peak energy-intensity correlations
Sawant, Disha; Amati, Lorenzo
2015-12-17
Gamma Ray Bursts (GRBs) are immensely energetic explosions radiating up to 10{sup 54} erg of energy isotropically (E{sub iso}) and they are observed within a wide range of redshift (from ∼ 0.01 up to ∼ 9). Such enormous power and high redshift point at these phenomena being highly favorable to investigate the history and evolution of our universe. The major obstacle in their application as cosmological study-tools is to find a way to standardize the GRBs, for instance similar to SNe Ia. With respect to this goal, the correlation between spectral peak energy (E{sub p,i}) and the “intensity” is a positively useful and investigated criterion. Moreover, it has been demonstrated that, through the E{sub p,i} – E{sub iso} correlation, the current data set of GRBs can already contribute to the independent evidence of the matter density Ω{sub M} being ∼ 0.3 for a flat universe scenario. We try to inspect and compare the correlations of E{sub p,i} with different intensity indicators (e.g., radiated energy, average and peak luminosity, bolometric vs. monochromatic quantities, etc.) both in terms of intrinsic dispersion and precise estimation of Ω{sub M}. The outcome of such studies are further analyzed in verifying the reliability of the correlations for both GRB physics and their standardization for cosmology.
Average local ionization energy generalized to correlated wavefunctions
Ryabinkin, Ilya G.; Staroverov, Viktor N.
2014-08-28
The average local ionization energy function introduced by Politzer and co-workers [Can. J. Chem. 68, 1440 (1990)] as a descriptor of chemical reactivity has a limited utility because it is defined only for one-determinantal self-consistent-field methods such as the Hartree–Fock theory and the Kohn–Sham density-functional scheme. We reinterpret the negative of the average local ionization energy as the average total energy of an electron at a given point and, by rewriting this quantity in terms of reduced density matrices, arrive at its natural generalization to correlated wavefunctions. The generalized average local electron energy turns out to be the diagonal part of the coordinate representation of the generalized Fock operator divided by the electron density; it reduces to the original definition in terms of canonical orbitals and their eigenvalues for one-determinantal wavefunctions. The discussion is illustrated with calculations on selected atoms and molecules at various levels of theory.
Gamma Ray Bursts Spectral-Energy correlations: recent results
NASA Astrophysics Data System (ADS)
Ghirlanda, Giancarlo
2011-02-01
The correlations between the rest frame peak of the νFν spectrum of GRBs (Epeak) and their isotropic energy (Eiso) or luminosity (Liso) could have several implications for the understanding of the GRB prompt emission. These correlations are presently founded on the time-averaged spectral properties of a sample of 95 bursts, with measured redshifts, collected by different instruments in the last 13 years (pre-Fermi). One still open issue is wether these correlations have a physical origin or are due to instrumental selection effects. By studying 10 long and 14 short GRBs detected by Fermi we find that a strong time-resolved correlation between Epeak and the luminosity Liso is present within individual GRBs and that it is consistent with the time-integrated correlation. This result is a direct proof of the existence in both short and long GRBs of a similar physical link between the hardness and the luminosity which is not due to instrumental selection effects. The origin of the Epeak - Liso correlation should be searched in the radiation mechanism of the prompt emission.
Liouville Field Theory and Log-Correlated Random Energy Models
NASA Astrophysics Data System (ADS)
Cao, Xiangyu; Rosso, Alberto; Santachiara, Raoul; Le Doussal, Pierre
2017-03-01
An exact mapping is established between the c ≥25 Liouville field theory (LFT) and the Gibbs measure statistics of a thermal particle in a 2D Gaussian free field plus a logarithmic confining potential. The probability distribution of the position of the minimum of the energy landscape is obtained exactly by combining the conformal bootstrap and one-step replica symmetry-breaking methods. Operator product expansions in the LFT allow us to unveil novel universal behaviors of the log-correlated random energy class. High-precision numerical tests are given.
Liouville Field Theory and Log-Correlated Random Energy Models.
Cao, Xiangyu; Rosso, Alberto; Santachiara, Raoul; Le Doussal, Pierre
2017-03-03
An exact mapping is established between the c≥25 Liouville field theory (LFT) and the Gibbs measure statistics of a thermal particle in a 2D Gaussian free field plus a logarithmic confining potential. The probability distribution of the position of the minimum of the energy landscape is obtained exactly by combining the conformal bootstrap and one-step replica symmetry-breaking methods. Operator product expansions in the LFT allow us to unveil novel universal behaviors of the log-correlated random energy class. High-precision numerical tests are given.
Symmetry energy of nucleonic matter with tensor correlations
NASA Astrophysics Data System (ADS)
Hen, Or; Li, Bao-An; Guo, Wen-Jun; Weinstein, L. B.; Piasetzky, Eli
2015-02-01
The nuclear symmetry energy (Esym(ρ ) ) is a vital ingredient of our understanding of many processes, from heavy-ion collisions to neutron stars structure. While the total nuclear symmetry energy at nuclear saturation density (ρ0) is relatively well determined, its value at supranuclear densities is not. The latter can be better constrained by separately examining its kinetic and potential terms and their density dependencies. The kinetic term of the symmetry energy, Esymkin(ρ0) , equals the difference in the per-nucleon kinetic energy between pure neutron matter (PNM) and symmetric nuclear matter (SNM), often calculated using a simple Fermi gas model. However, experiments show that tensor force induced short-range correlations (SRC) between proton-neutron pairs shift nucleons to high momentum in SNM, where there are equal numbers of neutrons and protons, but have almost no effect in PNM. We present an approximate analytical expression for Esymkin(ρ0) of correlated nucleonic matter. In our model, Esymkin(ρ0) =-10 MeV, which differs significantly from +12.5 MeV for the widely-used free Fermi gas model. This result is consistent with our analysis of recent data on the free proton-to-neutron ratios measured in intermediate energy nucleus-nucleus collisions as well as with microscopic many-body calculations, and previous phenomenological extractions. We then use our calculated Esymkin(ρ ) in combination with the known total symmetry energy and its density dependence at saturation density to constrain the value and density dependence of the potential part and to extrapolate the total symmetry energy to supranuclear densities.
Selection effects on GRB spectral-energy correlations
Nava, Lara; Ghirlanda, Giancarlo; Ghisellini, Gabriele
2009-05-25
Instrumental selection effects can act upon the estimates of the peak energy E{sub peak}{sup obs}, the fluence F and the peak flux P of GRBs. If this were the case, then the correlations involving the corresponding rest frame quantities (i.e. E{sub peak}, E{sub obs} and the peak luminosity L{sub iso}) would be questioned. We estimated, as a function of E{sub peak}{sup obs}, the minimum peak flux necessary to trigger a GRB and the minimum fluence a burst must have to determine the value of E{sub peak}{sup obs} by considering different instruments (BATSE, Swift, BeppoSAX). We find that the latter dominates over the former. We then study the E{sub peak}{sup obs}-fluence (and flux) correlation in the observer plane. GRBs with redshift show well defined E{sub peak}{sup obs}-F and E{sub peak}{sup obs}-P correlations: in this planes the selection effects are present, but do not determine the found correlations. This is not true for Swift GRBs with redshift, for which the spectral analysis threshold does affect their distribution in the observer planes. Extending the sample to GRBs without z, we still find a significant E{sub peak}{sup obs}-F correlation, although with a larger scatter than that defined by GRBs with redshift. We find that 6% are outliers of the Amati correlation. The E{sub peak}{sup obs}-P correlation of GRBs with or without redshift is the same and no outlier is found among bursts without redshift.
Bubin, Sergiy; Adamowicz, Ludwik
2014-01-14
Benchmark variational calculations are performed for the seven lowest 1s{sup 2}2s np ({sup 1}P), n = 2…8, states of the beryllium atom. The calculations explicitly include the effect of finite mass of {sup 9}Be nucleus and account perturbatively for the mass-velocity, Darwin, and spin-spin relativistic corrections. The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. Basis sets of up to 12 500 optimized Gaussians are used. The maximum discrepancy between the calculated nonrelativistic and experimental energies of 1s{sup 2}2s np ({sup 1}P) →1s{sup 2}2s{sup 2} ({sup 1}S) transition is about 12 cm{sup −1}. The inclusion of the relativistic corrections reduces the discrepancy to bellow 0.8 cm{sup −1}.
Video quality assessment based on correlation between spatiotemporal motion energies
NASA Astrophysics Data System (ADS)
Yan, Peng; Mou, Xuanqin
2016-09-01
Video quality assessment (VQA) has been a hot research topic because of rapid increase of huge demand of video communications. From the earliest PSNR metric to advanced models that are perceptual aware, researchers have made great progress in this field by introducing properties of human vision system (HVS) into VQA model design. Among various algorithms that model the property of HVS perceiving motion, the spatiotemporal energy model has been validated to be high consistent with psychophysical experiments. In this paper, we take the spatiotemporal energy model into VQA model design by the following steps. 1) According to the pristine spatiotemporal energy model proposed by Adelson et al, we apply the linear filters, which are oriented in space-time and tuned in spatial frequency, to filter the reference and test videos respectively. The outputs of quadrature pairs of above filters are then squared and summed to give two measures of motion energy, which are named rightward and leftward energy responses, respectively. 2) Based on the pristine model, we calculate summation of the rightward and leftward energy responses as spatiotemporal features to represent perceptual quality information for videos, named total spatiotemporal motion energy maps. 3) The proposed FR-VQA model, named STME, is calculated with statistics based on the pixel-wise correlation between the total spatiotemporal motion energy maps of the reference and distorted videos. The STME model was validated on the LIVE VQA Database by comparing with existing FR-VQA models. Experimental results show that STME performs with excellent prediction accuracy and stays in state-of-the-art VQA models.
All-electron Hybrid Functional Treatment of Oxides using the FLAPW Method
NASA Astrophysics Data System (ADS)
Betzinger, Markus; Schlipf, Martin; Friedrich, Christoph; Ležaić, Marjana; Blügel, Stefan
2010-03-01
Hybrid functionals are a practical approximation for the exchange-correlation (xc) functional of density-functional theory. They combine a local or semi-local xc functional with nonlocal Hartree-Fock (HF) exchange and improve the band gap for semiconductors and insulators as well as the description of localized states. So far, most implementations for periodic systems employ a pseudopotential planewave approach. We present an efficient all-electron implementation in the context of the FLAPW methodology realized in the FLEUR (www.flapw.de) code. We report on the implementation of the PBE0 and HSE functionals where an auxiliary basis is constructed from products of LAPW basis functions and used to calculate the HF potential. The Coulomb matrix^1 then has a sparse form. Spatial and time-reversal symmetry is exploited in restricting the Brillouin zone sum in the nonlocal potential to an irreducible wedge. We give account on the efficiency of our concept and of the convergence of the self-consistency cycle. Finally we present results for a variety of oxides and compare those to results obtained with functionals based on the generalized gradient approximation. [1] Comput. Phys. Comm. 180, 347 (2009)
Correlation between biogas yield and chemical composition of energy crops.
Dandikas, V; Heuwinkel, H; Lichti, F; Drewes, J E; Koch, K
2014-12-01
The scope of this study was to investigate the influence of the chemical composition of energy crops on biogas and methane yield. In total, 41 different plants were analyzed in batch test and their chemical composition was determined. For acid detergent lignin (ADL) content below 10% of total solids, a significant negative correlation for biogas and methane yields (r≈-0.90) was observed. Based on a simple regression analysis, more than 80% of the sample variation can be explained through ADL. Based on a principal component analysis and multiple regression analysis, ADL and hemicellulose are suggested as suitable model variables for biogas yield potential predictions across plant species.
Correlation Energies from the Two-Component Random Phase Approximation.
Kühn, Michael
2014-02-11
The correlation energy within the two-component random phase approximation accounting for spin-orbit effects is derived. The resulting plasmon equation is rewritten-analogously to the scalar relativistic case-in terms of the trace of two Hermitian matrices for (Kramers-restricted) closed-shell systems and then represented as an integral over imaginary frequency using the resolution of the identity approximation. The final expression is implemented in the TURBOMOLE program suite. The code is applied to the computation of equilibrium distances and vibrational frequencies of heavy diatomic molecules. The efficiency is demonstrated by calculation of the relative energies of the Oh-, D4h-, and C5v-symmetric isomers of Pb6. Results within the random phase approximation are obtained based on two-component Kohn-Sham reference-state calculations, using effective-core potentials. These values are finally compared to other two-component and scalar relativistic methods, as well as experimental data.
Famini, George R; Aguiar, Denise; Payne, Marvin A; Rodriquez, Ryan; Wilson, Leland Y
2002-01-01
The theoretical linear solvation energy relationship (TLSER) has been used to correlate and characterize 44 nasal pungency threshold (NPT) values in man with parameters derived from semi-empirical molecular orbital theory. The resulting relationship provides good correlative (R2 > 0.92) and predictive (R2cy > 0.88) capability. In addition, the TLSER parameters are used as a molecular probe to attempt to understand the fundamental properties influencing nasal pungency.
Bytautas, Laimutis; Ruedenberg, Klaus
2008-06-07
A close approximation to the empirical potential energy curve of the neon dimer is obtained by coupled-cluster singles plus doubles plus noniterative triples calculations by using nonaugmented correlation-consistent basis sets without counterpoise corrections and complementing them by three-term extrapolations to the complete basis set limit. The potential energy is resolved into a self-consistent-field Hartree-Fock contribution and a correlation contribution. The latter is shown to decay in the long-range region in accordance with the empirical dispersion expansion.
A density functional for core-valence correlation energy
NASA Astrophysics Data System (ADS)
Ranasinghe, Duminda S.; Frisch, Michael J.; Petersson, George A.
2015-12-01
A density functional, ɛCV-DFT(ρc, ρv), describing the core-valence correlation energy has been constructed as a linear combination of ɛLY Pcorr(ρc), ɛV WN5corr(ρc, ρv), ɛPBEcorr(ρc, ρv), ɛSlaterex(ρc, ρv), ɛHCTHex(ρc, ρv), ɛHFex(ρc, ρv), and F CV -DFT (" separators=" N i , Z i ) , a function of the nuclear charges. This functional, with 6 adjustable parameters, reproduces (±0.27 kcal/mol rms error) a benchmark set of 194 chemical energy changes including 9 electron affinities, 18 ionization potentials, and 167 total atomization energies covering the first- and second-rows of the periodic table. This is almost twice the rms error (±0.16 kcal/mol) obtained with CCSD(T)/MTsmall calculations, but less than half the rms error (±0.65 kcal/mol) obtained with MP2/GTlargeXP calculations, and somewhat smaller than the rms error (±0.39 kcal/mol) obtained with CCSD/MTsmall calculations. The largest positive and negative errors from ɛCV-DFT(ρc, ρv) were 0.88 and -0.75 kcal/mol with the set of 194 core-valence energy changes ranging from +3.76 kcal/mol for the total atomization energy of propyne to -9.05 kcal/mol for the double ionization of Mg. Evaluation of the ɛCV-DFT(ρc, ρv) functional requires less time than a single SCF iteration, and the accuracy is adequate for any model chemistry based on the CCSD(T) level of theory.
NASA Astrophysics Data System (ADS)
Anno, Tosinobu; Teruya, Hirohide
1989-10-01
Relativistic effect Erel upon the total electronic energy of an atom is discussed with particular reference to obtaining the nonrelativistic total energy Eexact from the experimental total energy. Numerical values of this effect obtained by various authors by different nonempirical methods are compared for neutral atoms of rare-gas elements. It is shown that methods either of a Hartree-Fock-type or of a Dirac-Hartree-Fock-type give much the same Erel value for He through Ar. It is pointed out that Erel calculated with Hartree-Fock wave functions is not adequate for use in obtaining Eexact from the experimental total energy and that the Erel value calculated with wave functions including electron correlation should work well, although an actual demonstration can be done only for two-electron systems for lack of data. A semiempirical formula is therefore proposed, which is useful for least-squares fit of experimental total energies of isoelectronic series of atoms to extract nonrelativistic total energies along with the relativistic effect. From nonrelativistic energies thus derived, semiempirical values of correlation energies of atoms are obtained. The results thus obtained are in reasonable agreement with correlation energies derived by Clementi along somewhat different lines. The power series expansion in Z of the fitted formula for the He series shows that numerical values of expansion coefficients agree reasonably well with the corresponding values obtained by accurate relativistic and nonrelativistic Z expansion-type calculations.
NASA Astrophysics Data System (ADS)
Yao, Y. X.; Liu, C.; Liu, J.; Lu, W. C.; Wang, C. Z.; Ho, K. M.
2013-03-01
The recently introduced correlation matrix renormalization approximation (CMRA) was further developed by adopting a completely factorizable form for the renormalization z-factors, which assumes the validity of the Wick's theorem with respect to Gutzwiller wave function. This approximation (CMR-II) shows better dissociation behavior than the original one (CMR-I) based on the straightforward generalization of the Gutzwiller approximation to two-body interactions. We further improved the performance of CMRA by redefining the z-factors as a function of f(z) in CMR-II, which we call CMR-III. We obtained an analytical expression of f(z) by enforcing the equality in energy functional between CMR-III and full configuration interaction for the benchmark minimal basis H2. We show that CMR-III yields quite good binding energies and dissociation behaviors for various hydrogen clusters with converged basis set. Finally, we apply CMR-III to hydrogen crystal phases and compare the results with quantum Monte Carlo. Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. Ames Laboratory is operated for the U.S. DOE by Iowa State University under Contract No. DE-AC02-07CH11358.
Gradient corrections to the exchange-correlation free energy
Sjostrom, Travis; Daligault, Jerome
2014-10-07
We develop the first-order gradient correction to the exchange-correlation free energy of the homogeneous electron gas for use in finite-temperature density functional calculations. Based on this, we propose and implement a simple temperature-dependent extension for functionals beyond the local density approximation. These finite-temperature functionals show improvement over zero-temperature functionals, as compared to path-integral Monte Carlo calculations for deuterium equations of state, and perform without computational cost increase compared to zero-temperature functionals and so should be used for finite-temperature calculations. Furthermore, while the present functionals are valid at all temperatures including zero, non-negligible difference with zero-temperature functionals begins at temperatures above 10 000 K.
Gradient corrections to the exchange-correlation free energy
Sjostrom, Travis; Daligault, Jerome
2014-10-07
We develop the first-order gradient correction to the exchange-correlation free energy of the homogeneous electron gas for use in finite-temperature density functional calculations. Based on this, we propose and implement a simple temperature-dependent extension for functionals beyond the local density approximation. These finite-temperature functionals show improvement over zero-temperature functionals, as compared to path-integral Monte Carlo calculations for deuterium equations of state, and perform without computational cost increase compared to zero-temperature functionals and so should be used for finite-temperature calculations. Furthermore, while the present functionals are valid at all temperatures including zero, non-negligible difference with zero-temperature functionals begins at temperatures abovemore » 10 000 K.« less
Low-energy Model for Strongly Correlated Oxides
NASA Astrophysics Data System (ADS)
Liu, Shiu
We provide a detailed derivation of the low-energy model for site-diluted strongly correlated oxides, an example being Zn-diluted La2CuO 4, in the limit of low doping together with a study of the ground-state properties of that model. The generally complicated Hamiltonian on the energy scale of the most relevant atomic orbitals is systematically downfolded to an effective model containing only spin-spin interactions using several techniques. In our study, beginning with the site-diluted three-band Hubbard model for La2ZnxCu(1- x)O4, we first determine the hybridized electronic states of CuO4 and ZnO4 plaquettes within the CuO2 planes utilizing Wannier-orthogonalization of oxygen orbitals and cell-perturbation of the Hamiltonian of each plaquett. Qualitatively, we find that the hybridization of zinc and oxygen orbitals can result in an impurity state with the energy epsilon, which is lower than the effective Hubbard gap U. Then we apply canonical transformation in the limit of the effective hopping integral t << epsilon, U, to obtain the low-energy, spin-only Hamiltonian, which includes terms of the order t2/U, t4/epsilon3, and t 4/Uepsilon2. In other words, besides the usual diluted nearest-neighbor superexchange J-terms of order t2/U, the low-energy model contains impurity-mediated, further-neighbor frustrating interactions among the Cu spins surrounding Zn-sites in an otherwise unfrustrated antiferromagnetic background. These terms, denoted as J'Zn and J''Zn , are of order t4/epsilon3 and can be substantial when epsilon ˜ U/2, the latter value corresponding to the realistic CuO2 parameters. The other further-neighbor Cu spin interactions are of order t 4/U3, which are neglected in both pure and diluted systems, because they are much lesser than J'Zn and J''Zn and independent of impurity concentration. In order to verify this spin-only model, we subsequently apply the T-matrix approach to study the effect of impurities on the antiferromagnetic order parameter
NASA Astrophysics Data System (ADS)
Kurth, Stefan; Perdew, John P.
1999-04-01
Since long-range electron-electron correlation is treated properly in the random phase approximation (RPA), we define short-range correlation as the correction to the RPA. The effects of short-range correlation are investigated here in the local spin density (LSD) approximation and the generalized gradient approximation (GGA). Results are presented for atoms, molecules, and jellium surfaces. It is found that (1) short-range correlation energies are less sensitive to the inclusion of density gradients than are full correlation energies, and (2) short-range correlation makes a surprisingly small contribution to surface and molecular atomization energies. In order to improve the accuracy of electronic-structure calculations, we therefore combine a GGA treatment of short-range correlation with a full RPA treatment of the exchange-correlation energy. This approach leads to jellium surface energies close to those of the LSD approximation for exchange and correlation together (but not for each separately).
The role of correlation in the ground state energy of confined helium atom
Aquino, N.
2014-01-14
We analyze the ground state energy of helium atom confined by spherical impenetrable walls, and the role of the correlation energy in the total energy. The confinement of an atom in a cavity is one way in which we can model the effect of the external pressure on an atom. The calculations of energy of the system are carried out by the variational method. We find that the correlation energy remains almost constant for a range values of size of the boxes analyzed.
Electron-electron correlations in square-well quantum dots: direct energy minimization approach.
Goto, Hidekazu; Hirose, Kikuji
2011-04-01
Electron-electron correlations in two-dimensional square-well quantum dots are investigated using the direct energy minimization scheme. Searches for groundstate charges and spin configurations are performed with varying the sizes of dots and the number of electrons. For a two-electron system, a standout difference between the configurations with and without counting correlation energy is demonstrated. The emergence and melting of Wigner-molecule-like structures arising from the interplay between the kinetic energy and Coulombic interaction energy are described. Electron-electron correlation energies and addition energy spectra are calculated, and special electron numbers related to peculiar effects of the square well are extracted.
Ameri, Shideh Kabiri; Singh, Pramod K; Dokmeci, Mehmet R; Khademhosseini, Ali; Xu, Qiaobing; Sonkusale, Sameer R
2014-04-15
We present a portable lab-on-chip device for high-throughput trapping and lysis of single cells with in-situ impedance monitoring in an all-electronic approach. The lab-on-chip device consists of microwell arrays between transparent conducting electrodes within a microfluidic channel to deliver and extract cells using alternating current (AC) dielectrophoresis. Cells are lysed with high efficiency using direct current (DC) electric fields between the electrodes. Results are presented for trapping and lysis of human red blood cells. Impedance spectroscopy is used to estimate the percentage of filled wells with cells and to monitor lysis. The results show impedance between electrodes decreases with increase in the percentage of filled wells with cells and drops to a minimum after lysis. Impedance monitoring provides a reasonably accurate measurement of cell trapping and lysis. Utilizing an all-electronic approach eliminates the need for bulky optical components and cameras for monitoring.
NASA Astrophysics Data System (ADS)
Rury, Aaron S.; Mansour, Kamjou; Yu, Nan
2015-07-01
This study examines the capability to significantly suppress the frequency noise of a semiconductor distributed feedback diode laser using a universally applicable approach: a combination of a high-Q crystalline whispering gallery mode microresonator reference and the Pound-Drever-Hall locking scheme using an all-electronic servo loop. An out-of-loop delayed self-heterodyne measurement system demonstrates the ability of this approach to reduce a test laser's absolute line width by nearly a factor of 100. In addition, in-loop characterization of the laser stabilized using this method demonstrates a 1-kHz residual line width with reference to the resonator frequency. Based on these results, we propose that utilization of an all-electronic loop combined with the use of the wide transparency window of crystalline materials enable this approach to be readily applicable to diode lasers emitting in other regions of the electromagnetic spectrum, especially in the UV and mid-IR.
On the accuracy of second-order Møller-Plesset correlation energies
NASA Astrophysics Data System (ADS)
Flores, J. R.
1997-05-01
Accurate second-order Møller-Plesset correlation energies are computed and compared with several semi-empirical estimates of the total correlation energies including those provided by Clementi, Anno and Teruya, and the recent results of Davidson, Froese and co-workers, for atoms with ten, twelve and eighteen electrons. Somewhat surprisingly, the MP2 correlation energies present what is considered to be in good agreement with the newest estimates, especially when the behaviour with the nuclear charge is examined.
Lacey, R.A.; Elmaani, A.; Lauret, J.; Li, T.; Bauer, W.; Craig, D.; Cronqvist, M.; Gualtieri, E.; Hannuschke, S.; Reposeur, T.; Vander Molen, A.; Westfall, G.D.; Wilson, W.K.; Winfield, J.S.; Yee, J.; Yennello, S.; Nadasen, A.; Tickle, R.S.; Norbeck, E. National Superconducting Cyclotron Laboratory Department of Physics, Michigan State University, East Lansing, Michigan 48824-1321 Department of Physics, University of Michigan at Dearborn, Dearborn, Michigan 48128 Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 Department of Physics, University of Iowa, Iowa City, Iowa 52242 )
1993-03-01
Multifragment azimuthal correlation functions have been measured as a function of beam energy and impact parameter for the Ar+Sc system ([ital E]/[ital A]=35 to 115 MeV). The observed azimuthal correlation functions---which do not require corrections for dispersion of the reaction plane---exhibit strong asymmetries which are dependent on impact parameter and beam energy. Rotational collective motion and flow seem to dominate the correlation functions at low beam energies. It is proposed that multifragment azimuthal correlation functions can provide a useful probe for intermediate energy heavy ion reaction dynamics.
Correlations in intermediate energy two-proton removal reactions.
Wimmer, K; Bazin, D; Gade, A; Tostevin, J A; Baugher, T; Chajecki, Z; Coupland, D; Famiano, M A; Ghosh, T K; Grinyer, G F; Hodges, R; Howard, M E; Kilburn, M; Lynch, W G; Manning, B; Meierbachtol, K; Quarterman, P; Ratkiewicz, A; Sanetullaev, A; Simpson, E C; Stroberg, S R; Tsang, M B; Weisshaar, D; Winkelbauer, J; Winkler, R; Youngs, M
2012-11-16
We report final-state-exclusive measurements of the light charged fragments in coincidence with (26)Ne residual nuclei following the direct two-proton removal from a neutron-rich (28)Mg secondary beam. A Dalitz-plot analysis and comparisons with simulations show that a majority of the triple-coincidence events with two protons display phase-space correlations consistent with the (two-body) kinematics of a spatially correlated pair-removal mechanism. The fraction of such correlated events, 56(12)%, is consistent with the fraction of the calculated cross section, 64%, arising from spin S=0 two-proton configurations in the entrance-channel (shell-model) (28)Mg ground state wave function. This result promises access to an additional and more specific probe of the spin and spatial correlations of valence nucleon pairs in exotic nuclei produced as fast secondary beams.
NASA Astrophysics Data System (ADS)
Krieger, J. B.; Chen, Jiqiang; Iafrate, G. J.; Savin, A.
1998-03-01
We have obtained an analytic approximation to E_c(r_g, ζ,G) where G is an energy gap separating the occupied and unoccupied states of a homogeneous electron gas for ζ=3D0 and ξ=3D1. When G=3D0, E_c(r_g, ζ) reduces to the usual LSD result. This functional is employed in calculating correlation energies for unpolarized atoms and ions for Z <= 18 by taking G[n]=3D1/8|nabla ln n|^2, which reduces to the ionization energy in the large r limit in an exact Kohn-Sham (KS) theory. The resulting functional is self-interaction-corrected employing a method which is invariant under a unitary transformation. We find that the application of this approach to the calculation of the Ec functional reduces the error in the LSD result by more than 95%. When the value of G is approximately corrected to include the effect of higher lying unoccupied localized states, the resulting values of Ec are within a few percent of the exact results.
NMR shieldings from density functional perturbation theory: GIPAW versus all-electron calculations
NASA Astrophysics Data System (ADS)
de Wijs, G. A.; Laskowski, R.; Blaha, P.; Havenith, R. W. A.; Kresse, G.; Marsman, M.
2017-02-01
We present a benchmark of the density functional linear response calculation of NMR shieldings within the gauge-including projector-augmented-wave method against all-electron augmented-plane-wave+local-orbital and uncontracted Gaussian basis set results for NMR shieldings in molecular and solid state systems. In general, excellent agreement between the aforementioned methods is obtained. Scalar relativistic effects are shown to be quite large for nuclei in molecules in the deshielded limit. The small component makes up a substantial part of the relativistic corrections.
Future directions for probing two and three nucleon short-range correlations at high energies
Frankfurt, Leonid; Sargsian, Misak; Strikman, Mark
2008-10-13
We summarize recent progress in the studies of the short-rang correlations (SRC) in nuclei in high energy electron and hadron nucleus scattering and suggest directions for the future high energy studies aimed at establishing detailed structure of two-nucleon SRCs, revealing structure of three nucleon SRC correlations and discovering non-nucleonic degrees of freedom in nuclei.
Energy dissipation from a correlated system driven out of equilibrium
NASA Astrophysics Data System (ADS)
Rameau, J. D.; Freutel, S.; Kemper, A. F.; Sentef, M. A.; Freericks, J. K.; Avigo, I.; Ligges, M.; Rettig, L.; Yoshida, Y.; Eisaki, H.; Schneeloch, J.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Johnson, P. D.; Bovensiepen, U.
2016-12-01
In complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can be used to separate electron-boson interactions from electron-electron interactions. We demonstrate a quantitative analysis of a well-defined electron-boson interaction in the unoccupied spectrum of the cuprate Bi2Sr2CaCu2O8+x characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments.
Energy dissipation from a correlated system driven out of equilibrium
Rameau, J. D.; Freutel, S.; Kemper, A. F.; Sentef, M. A.; Freericks, J. K.; Avigo, I.; Ligges, M.; Rettig, L.; Yoshida, Y.; Eisaki, H.; Schneeloch, J.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Johnson, P. D.; Bovensiepen, U.
2016-12-20
We report that in complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can be used to separate electron–boson interactions from electron–electron interactions. In conclusion, we demonstrate a quantitative analysis of a well-defined electron–boson interaction in the unoccupied spectrum of the cuprate Bi_{2}Sr_{2}CaCu_{2}O_{8+x} characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments.
Energy dissipation from a correlated system driven out of equilibrium
Rameau, J. D.; Freutel, S.; Kemper, A. F.; ...
2016-12-20
We report that in complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can bemore » used to separate electron–boson interactions from electron–electron interactions. In conclusion, we demonstrate a quantitative analysis of a well-defined electron–boson interaction in the unoccupied spectrum of the cuprate Bi2Sr2CaCu2O8+x characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments.« less
Energy dissipation from a correlated system driven out of equilibrium
Rameau, J. D.; Freutel, S.; Kemper, A. F.; Sentef, M. A.; Freericks, J. K.; Avigo, I.; Ligges, M.; Rettig, L.; Yoshida, Y.; Eisaki, H.; Schneeloch, J.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Johnson, P. D.; Bovensiepen, U.
2016-01-01
In complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can be used to separate electron–boson interactions from electron–electron interactions. We demonstrate a quantitative analysis of a well-defined electron–boson interaction in the unoccupied spectrum of the cuprate Bi2Sr2CaCu2O8+x characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments. PMID:27996009
Delayed correlation between turbulent energy injection and dissipation.
Pearson, Bruce R; Yousef, Tarek A; Haugen, Nils Erland L; Brandenburg, Axel; Krogstad, Per-Age
2004-11-01
The dimensionless kinetic energy dissipation rate C(epsilon) is estimated from numerical simulations of statistically stationary isotropic box turbulence that is slightly compressible. The Taylor microscale Reynolds number (Re(lambda)) range is 20< or approximately equal to Re(lambda) < or approximately equal to 220 and the statistical stationarity is achieved with a random phase forcing method. The strong Re(lambda) dependence of C(epsilon) abates when Re(lambda) approximately 100 after which C(epsilon) slowly approaches approximately 0.5, a value slightly different from previously reported simulations but in good agreement with experimental results. If C(epsilon) is estimated at a specific time step from the time series of the quantities involved it is necessary to account for the time lag between energy injection and energy dissipation. Also, the resulting value can differ from the ensemble averaged value by up to +/-30%. This may explain the spread in results from previously published estimates of C(epsilon).
NASA Astrophysics Data System (ADS)
Ishida, Toyokazu
2008-09-01
In this study, we investigated the electronic character of protein environment in enzymatic processes by performing all-electron QM calculations based on the fragment molecular orbital (FMO) method. By introducing a new computational strategy combining all-electron QM analysis with ab initio QM/MM modeling, we investigated the details of molecular interaction energy between a reactive substrate and amino acid residues at a catalytic site. For a practical application, we selected the chorismate mutase catalyzed reaction as an example. Because the computational time required to perform all-electron QM reaction path searches was very large, we employed the ab initio QM/MM modeling technique to construct reliable reaction profiles and performed all-electron FMO calculations for the selected geometries. The main focus of the paper is to analyze the details of electrostatic stabilization, which is considered to be the major feature of enzymatic catalyses, and to clarify how the electronic structure of proteins is polarized in response to the change in electron distribution of the substrate. By performing interaction energy decomposition analysis from a quantum chemical viewpoint, we clarified the relationship between the location of amino acid residues on the protein domain and the degree of electronic polarization of each residue. In particular, in the enzymatic transition state, Arg7, Glu78, and Arg90 are highly polarized in response to the delocalized electronic character of the substrate, and as a result, a large amount of electrostatic stabilization energy is stored in the molecular interaction between the enzyme and the substrate and supplied for transition state stabilization.
Ishida, Toyokazu
2008-09-28
In this study, we investigated the electronic character of protein environment in enzymatic processes by performing all-electron QM calculations based on the fragment molecular orbital (FMO) method. By introducing a new computational strategy combining all-electron QM analysis with ab initio QM/MM modeling, we investigated the details of molecular interaction energy between a reactive substrate and amino acid residues at a catalytic site. For a practical application, we selected the chorismate mutase catalyzed reaction as an example. Because the computational time required to perform all-electron QM reaction path searches was very large, we employed the ab initio QM/MM modeling technique to construct reliable reaction profiles and performed all-electron FMO calculations for the selected geometries. The main focus of the paper is to analyze the details of electrostatic stabilization, which is considered to be the major feature of enzymatic catalyses, and to clarify how the electronic structure of proteins is polarized in response to the change in electron distribution of the substrate. By performing interaction energy decomposition analysis from a quantum chemical viewpoint, we clarified the relationship between the location of amino acid residues on the protein domain and the degree of electronic polarization of each residue. In particular, in the enzymatic transition state, Arg7, Glu78, and Arg90 are highly polarized in response to the delocalized electronic character of the substrate, and as a result, a large amount of electrostatic stabilization energy is stored in the molecular interaction between the enzyme and the substrate and supplied for transition state stabilization.
Patchkovskii, Serguei
2006-02-28
Potential energy surfaces for all Born-Oppenheimer electronic states of IBr molecule correlating to the neutral (2)P ((2)P(3/2) and (2)P(1/2)) iodine and bromine are calculated for the first time. Electric dipole and polarizability curves (static and transition) are also determined. Calculations include scalar and spin-orbit relativistic effects within all-electron Douglas-Kroll two-component Hamiltonian. Electron correlation is treated with quasi-degenerate multi-reference second-order perturbation theory. Seven adiabatic electronic states (X (1)Sigma(+), A'(3)Pi(2), A (3)Pi(1), 1 (3)Pi(0-), B (3)Pi(0+), B'(3)Sigma, and 2 (3)Pi(0+)) exhibit significant covalent bonding, and can support vibrational states. Calculated spectroscopic parameters agree with experiment to better than 1000 cm(-1) (T(e)), 10 cm(-1) (omega(e)), and 0.05 Angstrom (r(e)). A new 1 (3)Pi(0-) state correlating to ground-state atoms is predicted at T(e) approximately 14 000 cm(-1), omega(e) approximately 80 cm(-1), and r(e) approximately 3.0 Angstrom. The second new state (2 (3)Pi(0+)) correlates to excited iodine atom, with T(e) approximately 20 000 cm(-1), omega(e) approximately 115 cm(-1), and r(e) approximately 3.3 Angstrom. Non-adiabatic coupling parameters are calculated for the four avoided crossings, which arise due to electronic spin-orbit interaction. Estimated parameters of the B (3)Pi(0+)/B'(3)Sigma crossing (R(c) approximately 3.32 Angstrom; V approximately 120 cm(-1)) agree with experimental values. The previously unsuspected 2 (3)Pi(0-)/1 (1)Sigma(-) crossing of two repulsive surfaces provides a new collisional deactivation channel for Br* atoms at relative velocities above 1000 m s(-1). Several repulsive states (including 1 (1)Pi(1) and 2 (3)Pi(1)) intersect the B/B' system near the avoided crossing point, and may affect dynamics of IBr in strong laser fields.
All-electron Kohn-Sham density functional theory on hierarchic finite element spaces
NASA Astrophysics Data System (ADS)
Schauer, Volker; Linder, Christian
2013-10-01
In this work, a real space formulation of the Kohn-Sham equations is developed, making use of the hierarchy of finite element spaces from different polynomial order. The focus is laid on all-electron calculations, having the highest requirement onto the basis set, which must be able to represent the orthogonal eigenfunctions as well as the electrostatic potential. A careful numerical analysis is performed, which points out the numerical intricacies originating from the singularity of the nuclei and the necessity for approximations in the numerical setting, with the ambition to enable solutions within a predefined accuracy. In this context the influence of counter-charges in the Poisson equation, the requirement of a finite domain size, numerical quadratures and the mesh refinement are examined as well as the representation of the electrostatic potential in a high order finite element space. The performance and accuracy of the method is demonstrated in computations on noble gases. In addition the finite element basis proves its flexibility in the calculation of the bond-length as well as the dipole moment of the carbon monoxide molecule.
Large-scale All-electron Density Functional Theory Calculations using Enriched Finite Element Method
NASA Astrophysics Data System (ADS)
Kanungo, Bikash; Gavini, Vikram
We present a computationally efficient method to perform large-scale all-electron density functional theory calculations by enriching the Lagrange polynomial basis in classical finite element (FE) discretization with atom-centered numerical basis functions, which are obtained from the solutions of the Kohn-Sham (KS) problem for single atoms. We term these atom-centered numerical basis functions as enrichment functions. The integrals involved in the construction of the discrete KS Hamiltonian and overlap matrix are computed using an adaptive quadrature grid based on gradients in the enrichment functions. Further, we propose an efficient scheme to invert the overlap matrix by exploiting its LDL factorization and employing spectral finite elements along with Gauss-Lobatto quadrature rules. Finally, we use a Chebyshev polynomial based acceleration technique to compute the occupied eigenspace in each self-consistent iteration. We demonstrate the accuracy, efficiency and scalability of the proposed method on various metallic and insulating benchmark systems, with systems ranging in the order of 10,000 electrons. We observe a 50-100 fold reduction in the overall computational time when compared to classical FE calculations while being commensurate with the desired chemical accuracy. We acknowledge the support of NSF (Grant No. 1053145) and ARO (Grant No. W911NF-15-1-0158) in conducting this work.
All-electron Kohn–Sham density functional theory on hierarchic finite element spaces
Schauer, Volker; Linder, Christian
2013-10-01
In this work, a real space formulation of the Kohn–Sham equations is developed, making use of the hierarchy of finite element spaces from different polynomial order. The focus is laid on all-electron calculations, having the highest requirement onto the basis set, which must be able to represent the orthogonal eigenfunctions as well as the electrostatic potential. A careful numerical analysis is performed, which points out the numerical intricacies originating from the singularity of the nuclei and the necessity for approximations in the numerical setting, with the ambition to enable solutions within a predefined accuracy. In this context the influence of counter-charges in the Poisson equation, the requirement of a finite domain size, numerical quadratures and the mesh refinement are examined as well as the representation of the electrostatic potential in a high order finite element space. The performance and accuracy of the method is demonstrated in computations on noble gases. In addition the finite element basis proves its flexibility in the calculation of the bond-length as well as the dipole moment of the carbon monoxide molecule.
Object-oriented Development of an All-electron Gaussian Basis DFT Code for Periodic Systems
NASA Astrophysics Data System (ADS)
Alford, John
2005-03-01
We report on the construction of an all-electron Gaussian-basis DFT code for systems periodic in one, two, and three dimensions. This is in part a reimplementation of algorithms in the serial code, GTOFF, which has been successfully applied to the study of crystalline solids, surfaces, and ultra-thin films. The current development is being carried out in an object-oriented parallel framework using C++ and MPI. Some rather special aspects of this code are the use of density fitting methodologies and the implementation of a generalized Ewald technique to do lattice summations of Coulomb integrals, which is typically more accurate than multipole methods. Important modules that have already been created will be described, for example, a flexible input parser and storage class that can parse and store generically tagged data (e.g. XML), an easy to use processor communication mechanism, and the integrals package. Though C++ is generally inferior to F77 in terms of optimization, we show that careful redesigning has allowed us to make up the run-time performance difference in the new code. Timing comparisons and scalability features will be presented. The purpose of this reconstruction is to facilitate the inclusion of new physics. Our goal is to study orbital currents using modified gaussian bases and external magnetic field effects in the weak and ultra-strong ( ˜10^5 T) field regimes. This work is supported by NSF-ITR DMR-0218957.
Predicting Pt-195 NMR chemical shift using new relativistic all-electron basis set.
Paschoal, D; Guerra, C Fonseca; de Oliveira, M A L; Ramalho, T C; Dos Santos, H F
2016-10-05
Predicting NMR properties is a valuable tool to assist the experimentalists in the characterization of molecular structure. For heavy metals, such as Pt-195, only a few computational protocols are available. In the present contribution, all-electron Gaussian basis sets, suitable to calculate the Pt-195 NMR chemical shift, are presented for Pt and all elements commonly found as Pt-ligands. The new basis sets identified as NMR-DKH were partially contracted as a triple-zeta doubly polarized scheme with all coefficients obtained from a Douglas-Kroll-Hess (DKH) second-order scalar relativistic calculation. The Pt-195 chemical shift was predicted through empirical models fitted to reproduce experimental data for a set of 183 Pt(II) complexes which NMR sign ranges from -1000 to -6000 ppm. Furthermore, the models were validated using a new set of 75 Pt(II) complexes, not included in the descriptive set. The models were constructed using non-relativistic Hamiltonian at density functional theory (DFT-PBEPBE) level with NMR-DKH basis set for all atoms. For the best model, the mean absolute deviation (MAD) and the mean relative deviation (MRD) were 150 ppm and 6%, respectively, for the validation set (75 Pt-complexes) and 168 ppm (MAD) and 5% (MRD) for all 258 Pt(II) complexes. These results were comparable with relativistic DFT calculation, 200 ppm (MAD) and 6% (MRD). © 2016 Wiley Periodicals, Inc.
Gong, Jian; Kim, Chang-Jin C J
2008-06-01
Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabrication and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1 : x (x < 1) mixing, in comparison to the previously considered n : m mixing (i.e., n and m unit droplets).
Gong, Jian; Kim, Chang-Jin “CJ”
2009-01-01
Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabricaion and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1:x (x < 1) mixing, in comparison to the previously considered n:m mixing (i.e., n and m unit droplets). PMID:18497909
Angular and Long Range Rapidity Correlations in Particle Production at High Energy
NASA Astrophysics Data System (ADS)
Kovner, Alex; Lublinsky, Michael
2013-01-01
We discuss the general mechanism leading to long-range rapidity and angular correlations produced in high energy collisions (the "ridge"). This effect naturally appears in the high energy QCD and is strongly sensitive to physics of the gluon saturation. We comment on various recent practical realizations of the main idea, paying special attention to Nc counting and stress the relevance of Pomeron loops.
Energy-Based Design Methodology for Air Vehicle Systems: Aerodynamic Correlation Study
2005-03-01
ENERGY -BASED DESIGN METHODOLOGY FOR AIR VEHICLE SYSTEMS : AERODYNAMIC CORRELATION STUDY AFOSR: FA9550-64-"t/Dr. John Schmisseur AFOSR-NA C>(4-1-0- I...drag estimation and vehicle-level utilization of energy . The exergy utilization of a wing in a steady, low subsonic, three-dimensional, viscous flow...5a. CONTRACT NUMBER Energy -Based Design Methodology For Air Vehicle 5b. GRANT NUMBER Systems : Aerodynamic Correlation Study FA9550,-64 (9 4-1-- !(1 5c
An optimal energy estimator to reduce correlated noise for the EXO-200 light readout
NASA Astrophysics Data System (ADS)
Davis, C. G.; Hall, C.; Albert, J. B.; Barbeau, P. S.; Beck, D.; Belov, V.; Breidenbach, M.; Brunner, T.; Burenkov, A.; Cao, G. F.; Cen, W. R.; Chambers, C.; Cleveland, B.; Coon, M.; Craycraft, A.; Daniels, T.; Danilov, M.; Daugherty, S. J.; Davis, J.; Delaquis, S.; Der Mesrobian-Kabakian, A.; DeVoe, R.; Didberidze, T.; Dilling, J.; Dolgolenko, A.; Dolinski, M. J.; Dunford, M.; Fairbank, W., Jr.; Farine, J.; Feldmeier, W.; Feyzbakhsh, S.; Fierlinger, P.; Fudenberg, D.; Gornea, R.; Graham, K.; Gratta, G.; Hughes, M.; Jewell, M. J.; Johnson, A.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Licciardi, C.; Lin, Y. H.; Ling, J.; MacLellan, R.; Marino, M. G.; Mong, B.; Moore, D.; Njoya, O.; Nelson, R.; Odian, A.; Ostrovskiy, I.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Retière, F.; Rowson, P. C.; Russell, J. J.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Tsang, R.; Twelker, K.; Vuilleumier, J.-L.; Waite, A.; Walton, J.; Walton, T.; Weber, M.; Wen, L. J.; Wichoski, U.; Wood, J.; Yang, L.; Yen, Y.-R.; Zeldovich, O. Ya.
2016-07-01
The energy resolution of the EXO-200 detector is limited by electronics noise in the measurement of the scintillation response. Here we present a new technique to extract optimal scintillation energy measurements for signals split across multiple channels in the presence of correlated noise. The implementation of these techniques improves the energy resolution of the detector at the neutrinoless double beta decay Q-value from [1.9641 ± 0.0039]% to [1.5820 ± 0.0044]%.
Mussard, Bastien; Rocca, Dario; Jansen, Georg; Ángyán, János G
2016-05-10
Starting from the general expression for the ground state correlation energy in the adiabatic-connection fluctuation-dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this famework, the ACFDT analog of the second order screened exchange (SOSEX) approximation leads to a logarithmic formula for the correlation energy similar to the direct RPA expression. Alternatively, the contribution of the exchange can be included in the kernel used to evaluate the response functions. In this case, the use of an approximate kernel is crucial to simplify the formalism and to obtain a correlation energy in logarithmic form. Technical details of the implementation of these methods are discussed, and it is shown that one can take advantage of density fitting or Cholesky decomposition techniques to improve the computational efficiency; a discussion on the numerical quadrature made on the frequency variable is also provided. A series of test calculations on atomic correlation energies and molecular reaction energies shows that exchange effects are instrumental for improvement over direct RPA results.
Dong Jianmin; Zuo Wei; Scheid, Werner
2011-07-01
A formula for the relationship between the {alpha}-decay energies (Q values) of superheavy nuclei (SHN) is presented, which is composed of the effects of Coulomb energy and symmetry energy. It can be employed not only to validate the experimental observations and measurements to a large extent, but also to predict the Q values of heaviest SHN with a high accuracy generally which will be very useful for future experiments. Furthermore, the shell closures in superheavy region and the effect of the symmetry energy on the stability of SHN against {alpha} decay are discussed with the help of this formula.
Spectrum-splitting approach for Fermi-operator expansion in all-electron Kohn-Sham DFT calculations
NASA Astrophysics Data System (ADS)
Motamarri, Phani; Gavini, Vikram; Bhattacharya, Kaushik; Ortiz, Michael
2017-01-01
We present a spectrum-splitting approach to conduct all-electron Kohn-Sham density functional theory (DFT) calculations by employing Fermi-operator expansion of the Kohn-Sham Hamiltonian. The proposed approach splits the subspace containing the occupied eigenspace into a core subspace, spanned by the core eigenfunctions, and its complement, the valence subspace, and thereby enables an efficient computation of the Fermi-operator expansion by reducing the expansion to the valence-subspace projected Kohn-Sham Hamiltonian. The key ideas used in our approach are as follows: (i) employ Chebyshev filtering to compute a subspace containing the occupied states followed by a localization procedure to generate nonorthogonal localized functions spanning the Chebyshev-filtered subspace; (ii) compute the Kohn-Sham Hamiltonian projected onto the valence subspace; (iii) employ Fermi-operator expansion in terms of the valence-subspace projected Hamiltonian to compute the density matrix, electron density, and band energy. We demonstrate the accuracy and performance of the method on benchmark materials systems involving silicon nanoclusters up to 1330 electrons, a single gold atom, and a six-atom gold nanocluster. The benchmark studies on silicon nanoclusters revealed a staggering fivefold reduction in the Fermi-operator expansion polynomial degree by using the spectrum-splitting approach for accuracies in the ground-state energies of ˜10-4Ha/atom with respect to reference calculations. Further, numerical investigations on gold suggest that spectrum splitting is indispensable to achieve meaningful accuracies, while employing Fermi-operator expansion.
Viñes, Francesc; Illas, Francesc
2017-03-30
The atomic and electronic structure of stoichiometric and reduced ZnO wurtzite has been studied using a periodic relativistic all electron hybrid density functional (PBE0) approach and numeric atom-centered orbital basis set with quality equivalent to aug-cc-pVDZ. To assess the importance of relativistic effects, calculations were carried out without and with explicit inclusion of relativistic effects through the zero order regular approximation. The calculated band gap is ∼0.2 eV smaller than experiment, close to previous PBE0 results including relativistic calculation through the pseudopotential and ∼0.25 eV smaller than equivalent nonrelativistic all electron PBE0 calculations indicating possible sources of error in nonrelativistic all electron density functional calculations for systems containing elements with relatively high atomic number. The oxygen vacancy formation energy converges rather fast with the supercell size, the predicted value agrees with previously hybrid density functional calculations and analysis of the electronic structure evidences the presence of localized electrons at the vacancy site with a concomitant well localized peak in the density of states ∼0.5 eV above the top of the valence band and a significant relaxation of the Zn atoms near to the oxygen vacancy. Finally, present work shows that accurate results can be obtained in systems involving large supercells containing up to ∼450 atoms using a numeric atomic-centered orbital basis set within a full all electron description including scalar relativistic effects at an affordable cost. © 2017 Wiley Periodicals, Inc.
NASA Astrophysics Data System (ADS)
Gulans, Andris; Kontur, Stefan; Meisenbichler, Christian; Nabok, Dmitrii; Pavone, Pasquale; Rigamonti, Santiago; Sagmeister, Stephan; Werner, Ute; Draxl, Claudia
2014-09-01
Linearized augmented planewave methods are known as the most precise numerical schemes for solving the Kohn-Sham equations of density-functional theory (DFT). In this review, we describe how this method is realized in the all-electron full-potential computer package, exciting. We emphasize the variety of different related basis sets, subsumed as (linearized) augmented planewave plus local orbital methods, discussing their pros and cons and we show that extremely high accuracy (microhartrees) can be achieved if the basis is chosen carefully. As the name of the code suggests, exciting is not restricted to ground-state calculations, but has a major focus on excited-state properties. It includes time-dependent DFT in the linear-response regime with various static and dynamical exchange-correlation kernels. These are preferably used to compute optical and electron-loss spectra for metals, molecules and semiconductors with weak electron-hole interactions. exciting makes use of many-body perturbation theory for charged and neutral excitations. To obtain the quasi-particle band structure, the GW approach is implemented in the single-shot approximation, known as G0W0. Optical absorption spectra for valence and core excitations are handled by the solution of the Bethe-Salpeter equation, which allows for the description of strongly bound excitons. Besides these aspects concerning methodology, we demonstrate the broad range of possible applications by prototypical examples, comprising elastic properties, phonons, thermal-expansion coefficients, dielectric tensors and loss functions, magneto-optical Kerr effect, core-level spectra and more.
Gulans, Andris; Kontur, Stefan; Meisenbichler, Christian; Nabok, Dmitrii; Pavone, Pasquale; Rigamonti, Santiago; Sagmeister, Stephan; Werner, Ute; Draxl, Claudia
2014-09-10
Linearized augmented planewave methods are known as the most precise numerical schemes for solving the Kohn-Sham equations of density-functional theory (DFT). In this review, we describe how this method is realized in the all-electron full-potential computer package, exciting. We emphasize the variety of different related basis sets, subsumed as (linearized) augmented planewave plus local orbital methods, discussing their pros and cons and we show that extremely high accuracy (microhartrees) can be achieved if the basis is chosen carefully. As the name of the code suggests, exciting is not restricted to ground-state calculations, but has a major focus on excited-state properties. It includes time-dependent DFT in the linear-response regime with various static and dynamical exchange-correlation kernels. These are preferably used to compute optical and electron-loss spectra for metals, molecules and semiconductors with weak electron-hole interactions. exciting makes use of many-body perturbation theory for charged and neutral excitations. To obtain the quasi-particle band structure, the GW approach is implemented in the single-shot approximation, known as G(0)W(0). Optical absorption spectra for valence and core excitations are handled by the solution of the Bethe-Salpeter equation, which allows for the description of strongly bound excitons. Besides these aspects concerning methodology, we demonstrate the broad range of possible applications by prototypical examples, comprising elastic properties, phonons, thermal-expansion coefficients, dielectric tensors and loss functions, magneto-optical Kerr effect, core-level spectra and more.
Density-Functional Theory Studies of Correlation Energy Effects at Metallic Surfaces.
NASA Astrophysics Data System (ADS)
Mohammed, Abdel-Raouf Eid
In this thesis we study the effects of correlation in the inhomogeneous electron gas at metallic surfaces. These studies are performed within the context of density-functional theory (DFT). Using accurate representations of the electronic density profile, we have estimated variationally the surface correlation energy of jellium metal. The accuracy of these estimates is founded in the assumption that the exchange -correlation energy functional of the density is approximated accurately by the wave-vector analysis method, and by the fact that the non-local exchange energy contributions are treated exactly. In contrast to the previously accepted conclusion that for surfaces correlation effects are as significant as exchange, our results indicate the ratio of these energies to lie between 34% - 97% over the metallic density range, the smaller ratios corresponding to the higher density metals. In this work we have also examined the local density (LDA) and gradient expansion approximations (GEA) (to O((DEL)('2))) for the correlation energy. We have demonstrated for realistic metal surface densities the cancellation of the errors in the LDA for exchange and correlation, and shown that the density profiles at surfaces would have to be unphysically slowly varying for the correlation energy GEA to converge. We have also studied the effects of correlation at surfaces by screening the exchange, and observe that the surface exchange energy for screened-Coulomb interaction decreases as the screening length is reduced. Thus, the more short-ranged the interaction, the easier it is to split the crystal in two. In addition we have derived the DFT first gradient correction coefficient in the GEA for the screened-Coulomb exchange energy, and shown it to be the same as that obtained within Hartree -Fock theory (HFT) for finite screening. This coefficient reduces to the DFT bare-Coulomb interaction value in the limit of no screening in which limit the HFT coefficient is singular. The GEA
Energy and daylighting: A correlation between quality of light and energy consciousness
Krug, N.
1997-12-31
Energy and Daylighting, an advanced topics graduate/professional elective has been established to help the student develop a deeper understanding of Architectural Daylighting, Energy Conserving Design, and Material/Construction/Methods through direct application. After a brief survey of the principles and applications of current and developing attitudes and techniques in energy conservation and natural lighting strategies is conducted (in order to build upon previous courses), an extensive exercise follows which allows the student the opportunity for direct applications. Both computer modeling/analysis and physical modeling (light box simulation with photographic documentation) are employed to focus attention on the interrelationships between natural lighting and passive energy conserving design--all within the context of establishing environmental (interior) quality and (exterior) design direction. As a result, students broaden their understanding of natural light and energy conservation as design tools; the importance of environmental responsibility, both built and natural environments; and using computer analysis as a design tool. This presentation centers around the activities and results obtained from explorations into Energy and Daylighting. Discussion will highlight the course objectives, the methodology involved in the studies, specific requirements and means of evaluation, a slide show of befores and afters (results), and a retrospective look at the course`s value, as well as future directions and implications.
Information Content of the Low-Energy Electric Dipole Strength: Correlation Analysis
Reinhard, P.-G.; Nazarewicz, Witold
2013-01-01
Background: Recent experiments on the electric dipole (E1) polarizability in heavy nuclei have stimulated theoretical interest in the low-energy electric dipole strength, both isovector and isoscalar. Purpose: We study the information content carried by the electric dipole strength with respect to isovector and isoscalar indicators characterizing bulk nuclear matter and finite nuclei. To separate isoscalar and isovector modes, and low-energy strength and giant resonances, we analyze the E1 strength as a function of the excitation energy E and momentum transfer q. Methods: We use the self-consistent nuclear density functional theory with Skyrme energy density functionals, augmented by the random phase approximation, to compute the E1 strength and covariance analysis to assess correlations between observables. Calculations are performed for the spherical, doubly magic nuclei 208Pb and 132Sn. Results: We demonstrate that E1 transition densities in the low-energy region below the giant dipole resonance exhibit appreciable state dependence and multinodal structures, which are fingerprints of weak collectivity. The correlation between the accumulated low-energy strength and the symmetry energy is weak, and dramatically depends on the energy cutoff assumed. On the other hand, a strong correlation is predicted between isovector indicators and the accumulated isovector strength at E around 20 MeV and momentum transfer q 0.65 fm 1. Conclusions: Momentum- and coordinate-space patterns of the low-energy dipole modes indicate a strong fragmentation into individual particle-hole excitations. The global measure of low-energy dipole strength correlates poorly with the nuclear symmetry energy and other isovector characteristics. Consequently, our results do not support the suggestion that there exists a collective pygmy dipole resonance, which is a strong indicator of nuclear isovector properties. By considering nonzero values of momentum transfer, one can isolate individual
Searching for squeezed particle-antiparticle correlations in high-energy heavy-ion collisions
Padula, Sandra S.; Socolowski, O. Jr.
2010-09-15
Squeezed correlations of particle-antiparticle pairs were predicted to exist if the hadron masses were modified in the hot and dense medium formed in high-energy heavy-ion collisions. Although well-established theoretically, they have not yet been observed experimentally. We suggest here a clear method to search for such a signal by analyzing the squeezed correlation functions in terms of measurable quantities. We illustrate this suggestion for simulated {phi}{phi} pairs at the Relativistic Heavy Ion Collider (RHIC) energies.
Impact of nonlocal correlations over different energy scales: A dynamical vertex approximation study
NASA Astrophysics Data System (ADS)
Rohringer, G.; Toschi, A.
2016-09-01
In this paper, we investigate how nonlocal correlations affect, selectively, the physics of correlated electrons over different energy scales, from the Fermi level to the band edges. This goal is achieved by applying a diagrammatic extension of dynamical mean field theory (DMFT), the dynamical vertex approximation (D Γ A ), to study several spectral and thermodynamic properties of the unfrustrated Hubbard model in two and three dimensions. Specifically, we focus first on the low-energy regime by computing the electronic scattering rate and the quasiparticle mass renormalization for decreasing temperatures at a fixed interaction strength. This way, we obtain a precise characterization of the several steps through which the Fermi-liquid physics is progressively destroyed by nonlocal correlations. Our study is then extended to a broader energy range, by analyzing the temperature behavior of the kinetic and potential energy, as well as of the corresponding energy distribution functions. Our findings allow us to identify a smooth but definite evolution of the nature of nonlocal correlations by increasing interaction: They either increase or decrease the kinetic energy w.r.t. DMFT depending on the interaction strength being weak or strong, respectively. This reflects the corresponding evolution of the ground state from a nesting-driven (Slater) to a superexchange-driven (Heisenberg) antiferromagnet (AF), whose fingerprints are, thus, recognizable in the spatial correlations of the paramagnetic phase. Finally, a critical analysis of our numerical results of the potential energy at the largest interaction allows us to identify possible procedures to improve the ladder-based algorithms adopted in the dynamical vertex approximation.
Correlation between surface free energy and anchoring energy of 6CHBT on polyimide surface
NASA Astrophysics Data System (ADS)
Borycki, Jerzy; Okulska-Bozek, Malgorzata; Kedzierski, Jerzy; Kojdecki, Marek A.
2002-06-01
Polyimides were prepared in the classical two-step method via poly(amic acids). Poly(amic acids) were obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'- (hexafluoroisopropylidene)diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA), 3,3',4,4'- diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'- oxydiphthalic anhydride (ODPA) and amines 4,4'-oxydianiline (ODA), 1,3-phenylenediamine (MPD), 1,4-phenylenediamine (PPD), 4,4'-diaminodiphenylmethane (MDA), 4,4'- ethylenedianiline (DAB), 2,4,6-trimethyl-1,3- phenylenediamine (TMPD), 4-methyl-1,3-phenylenediamine (MMPD) and 2,3,5,6-tetramethyl-1,4-phenylenediamine (DAD) in dimethylformamide. The indium tin oxide (ITO)-glass plates were spin-coated with the poly(amic acids) solutions and dried. A thermal imidization process was then carried out at 250 degree(s)C for 4 h. In this study the anchoring energies of 6CHBT molecules were evaluated on rubbing aligning layers of PI films. The polar anchoring energy coefficient was determined by wedge cell method. The surface free energy and its components of polyimide layers were determined by measuring the contact angles of water, ethylene glycol, formamide and diiodomethane drops on the rubbing polymer surfaces. The Lifshitz-van der Waals and acidic-basic components of surface free energies were found from van Oss equation.
NASA Astrophysics Data System (ADS)
Boettger, Jonathan C.; Ray, Asok K.
2000-07-01
The fluorite structure light-actinide dioxides, uranium dioxide and plutonium dioxide, are both known to be prototypical Mott-Hubbard insulators, with band gaps produced by strong Coulomb correlation effects that are not adequately accounted for in traditional density functional theory (DFT) calculations. Indeed, DFT electronic structure calculations for these two actinide dioxides have been shown to incorrectly predict metallic behavior. The highly-correlated electron effects exhibited by the actinide dioxides, combined with the large relativistic effects (including spin-orbit coupling) expected for any actinide compound, provide an extreme challenge for electronic structure theorists. For this reason, few fully-self-consistent DFT calculations have been carried out for the actinide dioxides, in general, and only one for plutonium dioxide. In that calculation, the troublesome 5f electrons were treated as core electrons, and spin-orbit coupling was ignored.
NASA Astrophysics Data System (ADS)
Ishida, Toyokazu
2008-09-01
To further understand the catalytic role of the protein environment in the enzymatic process, the author has analyzed the reaction mechanism of the Claisen rearrangement of Bacillus subtilis chorismate mutase (BsCM). By introducing a new computational strategy that combines all-electron QM calculations with ab initio QM/MM modelings, it was possible to simulate the molecular interactions between the substrate and the protein environment. The electrostatic nature of the transition state stabilization was characterized by performing all-electron QM calculations based on the fragment molecular orbital technique for the entire enzyme.
Ishida, Toyokazu
2008-09-17
To further understand the catalytic role of the protein environment in the enzymatic process, the author has analyzed the reaction mechanism of the Claisen rearrangement of Bacillus subtilis chorismate mutase (BsCM). By introducing a new computational strategy that combines all-electron QM calculations with ab initio QM/MM modelings, it was possible to simulate the molecular interactions between the substrate and the protein environment. The electrostatic nature of the transition state stabilization was characterized by performing all-electron QM calculations based on the fragment molecular orbital technique for the entire enzyme.
Moharana, Reetanjali; Razzaque, Soebur E-mail: srazzaque@uj.ac.za
2015-08-01
Cosmic neutrino events detected by the IceCube Neutrino Observatory with energy 0∼> 3 TeV have poor angular resolutions to reveal their origin. Ultrahigh-energy cosmic rays (UHECRs), with better angular resolutions at 0>6 EeV energies, can be used to check if the same astrophysical sources are responsible for producing both neutrinos and UHECRs. We test this hypothesis, with statistical methods which emphasize invariant quantities, by using data from the Pierre Auger Observatory, Telescope Array and past cosmic-ray experiments. We find that the arrival directions of the cosmic neutrinos are correlated with 0≥ 10 EeV UHECR arrival directions at confidence level ≈ 90%. The strength of the correlation decreases with decreasing UHECR energy and no correlation exists at energy 0∼ 6 EeV . A search in astrophysical databases within 3{sup o} of the arrival directions of UHECRs with energy 0≥ 10 EeV, that are correlated with the IceCube cosmic neutrinos, resulted in 18 sources from the Swift-BAT X-ray catalog with redshift z≤ 0.06. We also found 3 objects in the Kühr catalog of radio sources using the same criteria. The sources are dominantly Seyfert galaxies with Cygnus A being the most prominent member. We calculate the required neutrino and UHECR fluxes to produce the observed correlated events, and estimate the corresponding neutrino luminosity (25 TeV–2.2 PeV) and cosmic-ray luminosity (500 TeV–180 EeV), assuming the sources are the ones we found in the Swift-BAT and Kühr catalogs. We compare these luminosities with the X-ray luminosity of the corresponding sources and discuss possibilities of accelerating protons to 0∼> 10 EeV and produce neutrinos in these sources.
van Aggelen, Helen; Yang, Yang; Yang, Weitao
2014-05-14
Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in H2(+) and other single-bond systems. It gives surprisingly good non-bonded interaction energies--competitive with the ph-RPA--with the correct R(-6) asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.
Lorentz factor - Beaming corrected energy/luminosity correlations and GRB central engine models
NASA Astrophysics Data System (ADS)
Yi, Shuang-Xi; Lei, Wei-Hua; Zhang, Bing; Dai, Zi-Gao; Wu, Xue-Feng; Liang, En-Wei
2017-03-01
We work on a GRB sample whose initial Lorentz factors (Γ0) are constrained by the afterglow onset method and the jet opening angles (θj) are determined by the jet break time. We confirm the Γ0-Eγ,iso correlation by Liang et al. (2010), and the Γ0-Lγ,iso correlation by Lü et al. (2012). Furthermore, we find correlations between Γ0 and the beaming corrected γ-ray energy (Eγ) and mean γ-ray luminosity (Lγ). By also including the kinetic energy of the afterglow, we find rough correlations (with larger scatter) between Γ0 and the total (γ-ray plus kinetic) energy and the total mean luminosity, both for isotropic values and beaming corrected values: these correlations allow us to test the data with GRB central engine models. Limiting our sample to the GRBs that likely have a black hole central engine, we compare the data with theoretical predictions of two types of jet launching mechanisms from BHs, i.e. the non-magnetized ν ν bar -annihilation mechanism, and the strongly magnetized Blandford-Znajek (BZ) mechanism. We find that the data are more consistent with the latter mechanism, and discuss the implications of our findings for GRB jet composition.
Artacho, Paulina; Saravia, Julia; Ferrandière, Beatriz Decencière; Perret, Samuel; Le Galliard, Jean-François
2015-09-01
Phenotypic selection is widely accepted as the primary cause of adaptive evolution in natural populations, but selection on complex functional properties linking physiology, behavior, and morphology has been rarely quantified. In ectotherms, correlational selection on thermal physiology, thermoregulatory behavior, and energy metabolism is of special interest because of their potential coadaptation. We quantified phenotypic selection on thermal sensitivity of locomotor performance (sprint speed), thermal preferences, and resting metabolic rate in captive populations of an ectothermic vertebrate, the common lizard, Zootoca vivipara. No correlational selection between thermal sensitivity of performance, thermoregulatory behavior, and energy metabolism was found. A combination of high body mass and resting metabolic rate was positively correlated with survival and negatively correlated with fecundity. Thus, different mechanisms underlie selection on metabolism in lizards with small body mass than in lizards with high body mass. In addition, lizards that selected the near average preferred body temperature grew faster that their congeners. This is one of the few studies that quantifies significant correlational selection on a proxy of energy expenditure and stabilizing selection on thermoregulatory behavior.
Artacho, Paulina; Saravia, Julia; Ferrandière, Beatriz Decencière; Perret, Samuel; Le Galliard, Jean-François
2015-01-01
Phenotypic selection is widely accepted as the primary cause of adaptive evolution in natural populations, but selection on complex functional properties linking physiology, behavior, and morphology has been rarely quantified. In ectotherms, correlational selection on thermal physiology, thermoregulatory behavior, and energy metabolism is of special interest because of their potential coadaptation. We quantified phenotypic selection on thermal sensitivity of locomotor performance (sprint speed), thermal preferences, and resting metabolic rate in captive populations of an ectothermic vertebrate, the common lizard, Zootoca vivipara. No correlational selection between thermal sensitivity of performance, thermoregulatory behavior, and energy metabolism was found. A combination of high body mass and resting metabolic rate was positively correlated with survival and negatively correlated with fecundity. Thus, different mechanisms underlie selection on metabolism in lizards with small body mass than in lizards with high body mass. In addition, lizards that selected the near average preferred body temperature grew faster that their congeners. This is one of the few studies that quantifies significant correlational selection on a proxy of energy expenditure and stabilizing selection on thermoregulatory behavior. PMID:26380689
Bubin, Sergiy; Sharkey, Keeper L.; Adamowicz, Ludwik
2013-04-28
Very accurate variational nonrelativistic finite-nuclear-mass calculations employing all-electron explicitly correlated Gaussian basis functions are carried out for six Rydberg {sup 2}D states (1s{sup 2}nd, n= 6, Horizontal-Ellipsis , 11) of the {sup 7}Li and {sup 6}Li isotopes. The exponential parameters of the Gaussian functions are optimized using the variational method with the aid of the analytical energy gradient determined with respect to these parameters. The experimental results for the lower states (n= 3, Horizontal-Ellipsis , 6) and the calculated results for the higher states (n= 7, Horizontal-Ellipsis , 11) fitted with quantum-defect-like formulas are used to predict the energies of {sup 2}D 1s{sup 2}nd states for {sup 7}Li and {sup 6}Li with n up to 30.
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
Collaboration, The Pierre auger
2007-12-01
Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the highest energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [1]. The correlation has maximum significance for cosmic rays with energy greater than {approx} 6 x 10{sup 19} eV and AGN at a distance less than {approx} 75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest energies originate from extra-galactic sources close enough so that their flux is not significantly attenuated by interaction with the cosmic background radiation (the Greisen-Zatsepin-Kuzmin effect). The angular scale of the correlation observed is a few degrees, which suggests a predominantly light composition unless the magnetic fields are very weak outside the thin disk of our galaxy. Our present data do not identify AGN as the sources of cosmic rays unambiguously, and other candidate sources which are distributed as nearby AGN are not ruled out. We discuss the prospect of unequivocal identification of individual sources of the highest-energy cosmic rays within a few years of continued operation of the Pierre Auger Observatory.
Suppression of back-to-back particle-antiparticle correlations in high-energy nuclear collisions
Knoll, Joern
2011-04-15
Analytical formulas are presented which provide quantitative estimates for the suppression of the anticipated back-to-back particle-antiparticle correlations in high-energy nuclear collisions, due to both the finite duration of the transition dynamics and the continuous freeze-out. They show that the effect is unlikely to be observed.
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
NASA Astrophysics Data System (ADS)
Pierre Auger Collaboration; Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Argirò, S.; Arisaka, K.; Armengaud, E.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Atulugama, B. S.; Aublin, J.; Ave, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Barbosa, A. F.; Barnhill, D.; Barroso, S. L. C.; Bauleo, P.; Beatty, J. J.; Beau, T.; Becker, B. R.; Becker, K. H.; Bellido, J. A.; Benzvi, S.; Berat, C.; Bergmann, T.; Bernardini, P.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blasi, P.; Bleve, C.; Blümer, H.; Boháčová, M.; Bonifazi, C.; Bonino, R.; Brack, J.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Cai, B.; Camin, D. V.; Caramete, L.; Caruso, R.; Carvalho, W.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chye, J.; Clay, R. W.; Colombo, E.; Conceição, R.; Connolly, B.; Contreras, F.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Donato, C.; de Jong, S. J.; de La Vega, G.; de Mello, W. J. M.; de Mello Neto, J. R. T.; de Mitri, I.; de Souza, V.; Del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz, J. C.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dornic, D.; Dorofeev, A.; Dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Duvernois, M. A.; Engel, R.; Epele, L.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; San Luis, P. Facal; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrer, F.; Ferry, S.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fracchiolla, C. E.; Fulgione, W.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Geenen, H.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Herrero, R.; Gonçalves, P.; Gonçalves Do Amaral, M.; Gonzalez, D.; Gonzalez, J. G.; González, M.; Góra, D.; Gorgi, A.; Gouffon, P.; Grassi, V.; Grillo, A. F.; Grunfeld, C.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Hamilton, J. C.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hauschildt, T.; Healy, M. D.; Hebbeker, T.; Hebrero, G.; Heck, D.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J.; Horneffer, A.; Horvat, M.; Hrabovský, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kégl, B.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Krieger, A.; Krömer, O.; Kuempel, D.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lebrun, D.; Lebrun, P.; Lee, J.; de Oliveira, M. A. Leigui; Letessier-Selvon, A.; Leuthold, M.; Lhenry-Yvon, I.; López, R.; Lopez Agüera, A.; Lozano Bahilo, J.; García, R. Luna; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mancarella, G.; Manceñido, M. E.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Falcon, H. R. Marquez; Martello, D.; Martínez, J.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McCauley, T.; McEwen, M.; McNeil, R. R.; Medina, M. C.; Medina-Tanco, G.; Meli, A.; Melo, D.; Menichetti, E.; Menschikov, A.; Meurer, Chr.; Meyhandan, R.; Micheletti, M. I.; Miele, G.; Miller, W.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Morris, C.; Mostafá, M.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Newman-Holmes, C.; Newton, D.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Ohnuki, T.; Olinto, A.; Olmos-Gilbaja, V. M.; Ortiz, M.; Ortolani, F.; Ostapchenko, S.; Otero, L.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Pastor, S.; Patel, M.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; PȩKala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petrera, S.; Petrinca, P.; Petrov, Y.; Pichel, A.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pinto, T.; Pirronello, V.; Pisanti, O.; Platino, M.; Pochon, J.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Redondo, A.; Reucroft, S.; Revenu, B.; Rezende, F. A. S.; Ridky, J.; Riggi, S.; Risse, M.; Rivière, C.; Rizi, V.; Roberts, M.; Robledo, C.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Roth, M.; Rouillé-D'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scherini, V.; Schieler, H.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schovánek, P.; Schüssler, F.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Semikoz, D.; Settimo, M.; Shellard, R. C.; Sidelnik, I.; Siffert, B. B.; Sigl, G.; de Grande, N. Smetniansky; Smiałkowski, A.; Šmída, R.; Smith, A. G. K.; Smith, B. E.; Snow, G. R.; Sokolsky, P.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Takahashi, J.; Tamashiro, A.; Tamburro, A.; Taşcău, O.; Tcaciuc, R.; Thao, N. T.; Thomas, D.; Ticona, R.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Peixoto, C. J. Todero; Tomé, B.; Tonachini, A.; Torres, I.; Travnicek, P.; Tripathi, A.; Tristram, G.; Tscherniakhovski, D.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Galicia, J. F. Valdés; Valiño, I.; Valore, L.; van den Berg, A. M.; van Elewyck, V.; Vázquez, R. A.; Veberič, D.; Veiga, A.; Velarde, A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Warner, D.; Watson, A. A.; Westerhoff, S.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Wileman, C.; Winnick, M. G.; Wu, H.; Wundheiler, B.; Yamamoto, T.; Younk, P.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zech, A.; Zepeda, A.; Ziolkowski, M.
2008-04-01
Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the highest-energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [Pierre Auger Collaboration, Science 318 (2007) 938]. The correlation has maximum significance for cosmic rays with energy greater than ˜6 × 1019 eV and AGN at a distance less than ˜75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest-energies originate from extra-galactic sources close enough so that their flux is not significantly attenuated by interaction with the cosmic background radiation (the Greisen Zatsepin Kuz’min effect). The angular scale of the correlation observed is a few degrees, which suggests a predominantly light composition unless the magnetic fields are very weak outside the thin disk of our galaxy. Our present data do not identify AGN as the sources of cosmic rays unambiguously, and other candidate sources which are distributed as nearby AGN are not ruled out. We discuss the prospect of unequivocal identification of individual sources of the highest-energy cosmic rays within a few years of continued operation of the Pierre Auger Observatory.
NASA Astrophysics Data System (ADS)
Kanungo, Bikash; Gavini, Vikram
2017-01-01
We present a computationally efficient approach to perform large-scale all-electron density functional theory calculations by enriching the classical finite element basis with compactly supported atom-centered numerical basis functions that are constructed from the solution of the Kohn-Sham (KS) problem for single atoms. We term these numerical basis functions as enrichment functions, and the resultant basis as the enriched finite element basis. The compact support for the enrichment functions is obtained by using smooth cutoff functions, which enhances the conditioning and maintains the locality of the enriched finite element basis. The integrals involved in the evaluation of the discrete KS Hamiltonian and overlap matrix in the enriched finite element basis are computed using an adaptive quadrature grid that is constructed based on the characteristics of enrichment functions. Further, we propose an efficient scheme to invert the overlap matrix by using a blockwise matrix inversion in conjunction with special reduced-order quadrature rules, which is required to transform the discrete Kohn-Sham problem to a standard eigenvalue problem. Finally, we solve the resulting standard eigenvalue problem, in each self-consistent field iteration, by using a Chebyshev polynomial based filtering technique to compute the relevant eigenspectrum. We demonstrate the accuracy, efficiency, and parallel scalability of the proposed method on semiconducting and heavy-metallic systems of various sizes, with the largest system containing 8694 electrons. We obtain accuracies in the ground-state energies that are ˜1 mHa with reference ground-state energies employing classical finite element as well as Gaussian basis sets. Using the proposed formulation based on enriched finite element basis, for accuracies commensurate with chemical accuracy, we observe a staggering 50 -300 -fold reduction in the overall computational time when compared to classical finite element basis. Further, we find a
NASA Astrophysics Data System (ADS)
Ding, Xiaobin; Sun, Rui; Koike, Fumihiro; Kato, Daiji; Murakami, Izumi; Sakaue, Hiroyuki A.; Dong, Chenzhong
2017-03-01
The electron correlation effects and Breit interaction as well as Quantum Electro-Dynamics (QED) effects were expected to have important contribution to the energy level and transition properties of heavy highly charged ions. The ground states [Ne]3 s 23 p 63 d 2 and first excited states [Ne]3 s 23 p 53 d 3 of W54+ ion have been studied by using Multi-Configuration Dirac-Fock method with the implementation of Grasp2K package. A restricted active space method was employed to investigate the correlation contribution from different models. The Breit interaction and QED effects were taken into account in the relativistic configuration interaction calculation with the converged wavefunction. It is found that the correlation contribution from 3 s and 3 p orbital have important contribution to the energy level, transition wavelength and probability of the ground and the first excited state of W54+ ion.
Quantum Transfer Energy and Nonlocal Correlation in a Dimer with Time-Dependent Coupling Effect
NASA Astrophysics Data System (ADS)
El-Shishtawy, Reda M.; Berrada, K.; Haddon, Robert C.; Al-Hadeethi, Yas F.; Al-Heniti, Saleh H.; Raffah, Bahaaudin M.
2017-02-01
The presence of coherence phenomenon due to the interference of probability amplitude terms, is one of the most important features of quantum mechanics theory. Recent experiments show the presence of quantum processes whose coherence provided over suddenly large interval-time. In particular, photosynthetic mechanisms in light-harvesting complexes provide oscillatory behaviors in quantum mechanics due to quantum coherence. In this work, we investigate the coherent quantum transfer energy for a single-excitation and nonlocal correlation in a dimer system modelled by a two-level atom system with and without time-dependent coupling effect. We analyze and explore the required conditions that are feasible with real experimental realization for optimal transfer of quantum energy and generation of nonlocal quantum correlation. We show that the enhancement of the probability for a single-excitation transfer energy is greatly benefits from the combination of the energy detuning and time-dependent coupling effect. We investigate the presence of quantum correlations in the dimer using the entanglement of formation. We also find that the entanglement between the donor and acceptor is very sensitive to the physical parameters and it can be generated during the coherent energy transfer. On the other hand, we study the dynamical behavior of the quantum variance when performing a measurement on an observable of the density matrix operator. Finally, an interesting relationship between the transfer probability, entanglement and quantum variance is explored during the time evolution in terms of the physical parameters.
All-electron G W +Bethe-Salpeter calculations on small molecules
NASA Astrophysics Data System (ADS)
Hirose, Daichi; Noguchi, Yoshifumi; Sugino, Osamu
2015-05-01
Accuracy of the first-principles G W +Bethe-Salpeter equation (BSE) method is examined for low-energy excited states of small molecules. The standard formalism, which is based on the one-shot G W approximation and the Tamm-Dancoff approximation (TDA), is found to underestimate the optical gap of N2, CO, H2O ,C2H4 , and CH2O by about 1 eV. Possible origins are investigated separately for the effect of TDA and for the approximate schemes of the self-energy operator, which are known to cause overbinding of the electron-hole pair and overscreening of the interaction. By applying the known correction formula, we find the amount of the correction is too small to overcome the underestimated excitation energy. This result indicates a need for fundamental revision of the G W +BSE method rather than adjustment of the standard one. We expect that this study makes the problems in the current G W +BSE formalism clearer and provides useful information for further intrinsic development beyond the current framework.
Angular correlation between IceCube high-energy starting events and starburst sources
NASA Astrophysics Data System (ADS)
Moharana, Reetanjali; Razzaque, Soebur
2016-12-01
Starburst galaxies and star-forming regions in the Milkyway, with high rate of supernova activities, are candidate sources of high-energy neutrinos. Using a gamma-ray selected sample of these sources we perform statistical analysis of their angular correlation with the four-year sample of high-energy starting events (HESE), detected by the IceCube Neutrino Observatory. We find that the two samples (starburst galaxies and local star-forming regions) are correlated with cosmic neutrinos at ~ (2-3)σ (pre-trial) significance level, when the full HESE sample with deposited energy gtrsim 20 TeV is considered. However when we consider the HESE sample with deposited energy gtrsim 60 TeV, which is almost free of atmospheric neutrino and muon backgrounds, the significance of correlation decreased drastically. We perform a similar study for Galactic sources in the 2nd Catalog of Hard Fermi-LAT Sources (2FHL, >50 GeV) catalog as well, obtaining ~ (2-3)σ (pre-trial) correlation, however the significance of correlation increases with higher cutoff energy in the HESE sample for this case. We also fit available gamma-ray data from these sources using a pp interaction model and calculate expected neutrino fluxes. We find that the expected neutrino fluxes for most of the sources are at least an order of magnitude lower than the fluxes required to produce the HESE neutrinos from these sources. This puts the starburst sources being the origin of the IceCube HESE neutrinos in question.
NASA Astrophysics Data System (ADS)
Wu, Jianlan; Liu, Fan; Shen, Young; Cao, Jianshu; Silbey, Robert J.
2010-10-01
Understanding the mechanisms of efficient and robust energy transfer in light-harvesting systems provides new insights for the optimal design of artificial systems. In this paper, we use the Fenna-Matthews-Olson (FMO) protein complex and phycocyanin 645 (PC 645) to explore the general dependence on physical parameters that help maximize the efficiency and maintain its stability. With the Haken-Strobl model, the maximal energy transfer efficiency (ETE) is achieved under an intermediate optimal value of dephasing rate. To avoid the infinite temperature assumption in the Haken-Strobl model and the failure of the Redfield equation in predicting the Forster rate behavior, we use the generalized Bloch-Redfield (GBR) equation approach to correctly describe dissipative exciton dynamics, and we find that maximal ETE can be achieved under various physical conditions, including temperature, reorganization energy and spatial-temporal correlations in noise. We also identify regimes of reorganization energy where the ETE changes monotonically with temperature or spatial correlation and therefore cannot be optimized with respect to these two variables.
Recent improvements in size effects correlations for DBTT and upper shelf energy of ferritic steels
Kumar, A.S.; Louden, B.S. ); Garner, F.A.; Hamilton, M.L. )
1992-01-01
Currently available correlations for the effects of specimen size on the USE were developed for relatively ductile steels and will not serve as well when the steels become embrittled. Size effects correlations were developed recently for the impact properties of less ductile HT9 to be applied to other initially more ductile steels as they lose their ductility during irradiation. These new correlations successfully predict the ductile brittle transition temperature (DBTT) and the upper shelf energy (USE) of full size Charpy specimens based on subsize specimen data. The new DBTT and the USE correlations were tested against published experimental data on other ferritic steels and shown to perform successfully at lower USE particularly when both precracked and notched only specimens were employed.
Deliens, Tom; Clarys, Peter; De Bourdeaudhuij, Ilse; Deforche, Benedicte
2015-01-01
This study assessed personal and environmental correlates of Belgian university students’ soft and energy drink consumption and investigated whether these associations were moderated by gender or residency. Four hundred twenty-five university students completed a self-reported on-line questionnaire assessing socio-demographics, health status, soft and energy drink consumption, as well as personal and environmental factors related to soft and energy drink consumption. Multiple linear regression analyses were conducted. Students believing soft drink intake should be minimized (individual subjective norm), finding it less difficult to avoid soft drinks (perceived behavioral control), being convinced they could avoid soft drinks in different situations (self-efficacy), having family and friends who rarely consume soft drinks (modelling), and having stricter family rules about soft drink intake were less likely to consume soft drinks. Students showing stronger behavioral control, having stricter family rules about energy drink intake, and reporting lower energy drink availability were less likely to consume energy drinks. Gender and residency moderated several associations between psychosocial constructs and consumption. Future research should investigate whether interventions focusing on the above personal and environmental correlates can indeed improve university students’ beverage choices. PMID:26258790
Deliens, Tom; Clarys, Peter; De Bourdeaudhuij, Ilse; Deforche, Benedicte
2015-08-06
This study assessed personal and environmental correlates of Belgian university students' soft and energy drink consumption and investigated whether these associations were moderated by gender or residency. Four hundred twenty-five university students completed a self-reported on-line questionnaire assessing socio-demographics, health status, soft and energy drink consumption, as well as personal and environmental factors related to soft and energy drink consumption. Multiple linear regression analyses were conducted. Students believing soft drink intake should be minimized (individual subjective norm), finding it less difficult to avoid soft drinks (perceived behavioral control), being convinced they could avoid soft drinks in different situations (self-efficacy), having family and friends who rarely consume soft drinks (modelling), and having stricter family rules about soft drink intake were less likely to consume soft drinks. Students showing stronger behavioral control, having stricter family rules about energy drink intake, and reporting lower energy drink availability were less likely to consume energy drinks. Gender and residency moderated several associations between psychosocial constructs and consumption. Future research should investigate whether interventions focusing on the above personal and environmental correlates can indeed improve university students' beverage choices.
Farsightedness of the Correlation Energy in Polarizable Non-Metallic Nanostructures
NASA Astrophysics Data System (ADS)
Ambrosetti, Alberto; Ferri, Nicola; Distasio, Robert, Jr.; Tkatchenko, Alexandre
2015-03-01
The success of semi-local approaches to the electron correlation energy is commonly attributed to the relative nearsightedness of the electronic matter-a powerful concept introduced by Walter Kohn. However, recent theoretical and experimental evidence indicates that electron correlation can be characterized by strong ``action at a distance'', especially in low-dimensional polarizable nanomaterials. Here we systematically analyze the influence of relevant properties, namely dimensionality, topology and polarizability, on the convergence and power laws governing the correlation energy. Using an accurate model system of coupled quantum harmonic oscillators we find that many-body effects can induce collective and strongly delocalized charge-fluctuation modes. These modes are ultimately responsible for a marked non-locality of the response, and an unconventional power-law decay of the dispersion interaction, which significantly deviates from the asymptotic predictions of finite-order perturbative theories. Notably, the degree of farsightedness of the correlation energy could possibly be tuned, opening the way to an appropriate control of the interaction in complex polarizable nanostructures.
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; ...
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this report, we present a theoretical formalism to demonstrate themore » slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. In conclusion, we also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions« less
Elliott, Kyle H; Welcker, Jorg; Gaston, Anthony J; Hatch, Scott A; Palace, Vince; Hare, James F; Speakman, John R; Anderson, W Gary
2013-06-15
Thyroid hormones affect in vitro metabolic intensity, increase basal metabolic rate (BMR) in the lab, and are sometimes correlated with basal and/or resting metabolic rate (RMR) in a field environment. Given the difficulty of measuring metabolic rate in the field-and the likelihood that capture and long-term restraint necessary to measure metabolic rate in the field jeopardizes other measurements-we examined the possibility that circulating thyroid hormone levels were correlated with RMR in two free-ranging bird species with high levels of energy expenditure (the black-legged kittiwake, Rissa tridactyla, and thick-billed murre, Uria lomvia). Because BMR and daily energy expenditure (DEE) are purported to be linked, we also tested for a correlation between thyroid hormones and DEE. We examined the relationships between free and bound levels of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) with DEE and with 4-hour long measurements of post-absorptive and thermoneutral resting metabolism (resting metabolic rate; RMR). RMR but not DEE increased with T3 in both species; both metabolic rates were independent of T4. T3 and T4 were not correlated with one another. DEE correlated with body mass in kittiwakes but not in murres, presumably owing to the larger coefficient of variation in body mass during chick rearing for the more sexually dimorphic kittiwakes. We suggest T3 provides a good proxy for resting metabolism but not DEE in these seabird species.
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R.
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.
Dong, Hui; Lewis, Nicholas H C; Oliver, Thomas A A; Fleming, Graham R
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.
Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R.
2015-05-07
Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this report, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. In conclusion, we also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions
Discovery of an Io-correlated energy source for Io's hot plasma torus
NASA Technical Reports Server (NTRS)
Sandel, B. R.; Broadfoot, A. L.
1982-01-01
Energy flowing into Io's hot plasma torus from a local-time correlated source and from an Io-related source are discussed, and a correlation of the brightness of the ansae of the torus with the apparent orbital phase of Io is reported. It is shown that the energy flows cause an azimuthal modulation of the brightness of the torus that is correlated with the position of Io, and the plasma downstream from Io is shown to be brighter in S III 685-A emission, which indicates a higher electron temperature. Differences in electron temperature inferred from spectral analyses account for all observed differences in brightness, implying that no change in the composition or density of the hot plasma occurs. The mechanism regulating the Io-related source is clearly distinct from the mechanism driving the local time source, although both draw on the same pool of energy, and the combination of the two sources is easily capable of supplying all the energy radiated by the torus.
Discovery of an Io-correlated energy source for Io's hot plasma torus
NASA Astrophysics Data System (ADS)
Sandel, B. R.; Broadfoot, A. L.
1982-04-01
Energy flowing into Io's hot plasma torus from a local-time correlated source and from an Io-related source are discussed, and a correlation of the brightness of the ansae of the torus with the apparent orbital phase of Io is reported. It is shown that the energy flows cause an azimuthal modulation of the brightness of the torus that is correlated with the position of Io, and the plasma downstream from Io is shown to be brighter in S III 685-A emission, which indicates a higher electron temperature. Differences in electron temperature inferred from spectral analyses account for all observed differences in brightness, implying that no change in the composition or density of the hot plasma occurs. The mechanism regulating the Io-related source is clearly distinct from the mechanism driving the local time source, although both draw on the same pool of energy, and the combination of the two sources is easily capable of supplying all the energy radiated by the torus.
System, energy, and flavor dependence of jets through di-hadron correlations in heavy ion collisions
NASA Astrophysics Data System (ADS)
Nattrass, Christine
QCD predicts a phase transition in nuclear matter at high energy densities. This matter, called a Quark Gluon Plasma (QGP), should have very different properties from normal nuclear matter due to its high temperature and density. The Relativistic Heavy Ion Collider (RHIC) was built to study the QGP. Jets can act as a calibrated probe to examine the QGP, however, reconstruction of jets in a heavy ion environment is difficult. Therefore jets have been studied in heavy ion collisions by investigating the spatial correlations between two intermediate to high-pT hadrons in an event. Previous studies have shown that the near-side di-hadron correlation peak can be decomposed into two components, a jet-like correlation and the Ridge. The jet-like correlation is narrow in both azimuth and pseudorapidity, while the Ridge is narrow in azimuth but independent of pseudorapidity within STAR's acceptance. STAR's data from Cu+Cu and Au+Au collisions at sNN = 62 GeV and sNN = 200 GeV allow comparative studies of these components in different systems and at different energies. Data on correlations with both identified trigger particles and identified associated particles are presented, including the first studies of identified particle correlations in Cu+Cu and the energy dependence of these correlations. The yields are studied as a function of collision centrality, transverse momentum of the trigger particle, transverse momentum of the associated particle, and trigger and associated particle type. The data in this thesis indicate that the jet-like correlation component in heavy ion collisions is dominantly produced by vacuum fragmentation of hard scattered partons. The Ridge component is not present in p+p or d+Au collisions. The Ridge yield is consistent between systems for the same Npart and has properties similar to the bulk. Theoretical mechanisms for the production of the Ridge include parton recombination, collisional energy loss in the medium (momentum kicks), and gluon
NASA Astrophysics Data System (ADS)
Yucesoy, Burcu; Machta, Jonathan; Katzgraber, Helmut G.
2013-01-01
We present the results of a large-scale numerical study of the equilibrium three-dimensional Edwards-Anderson Ising spin glass with Gaussian disorder. Using parallel tempering (replica exchange) Monte Carlo we measure various static, as well as dynamical quantities, such as the autocorrelation times and round-trip times for the parallel tempering Monte Carlo method. The correlation between static and dynamic observables for 5000 disorder realizations and up to 1000 spins down to temperatures at 20% of the critical temperature is examined. Our results show that autocorrelation times are directly correlated with the roughness of the free-energy landscape.
Wave energy level and geographic setting correlate with Florida beach water quality.
Feng, Zhixuan; Reniers, Ad; Haus, Brian K; Solo-Gabriele, Helena M; Kelly, Elizabeth A
2016-03-15
Many recreational beaches suffer from elevated levels of microorganisms, resulting in beach advisories and closures due to lack of compliance with Environmental Protection Agency guidelines. We conducted the first statewide beach water quality assessment by analyzing decadal records of fecal indicator bacteria (enterococci and fecal coliform) levels at 262 Florida beaches. The objectives were to depict synoptic patterns of beach water quality exceedance along the entire Florida shoreline and to evaluate their relationships with wave condition and geographic location. Percent exceedances based on enterococci and fecal coliform were negatively correlated with both long-term mean wave energy and beach slope. Also, Gulf of Mexico beaches exceeded the thresholds significantly more than Atlantic Ocean ones, perhaps partially due to the lower wave energy. A possible linkage between wave energy level and water quality is beach sand, a pervasive nonpoint source that tends to harbor more bacteria in the low-wave-energy environment.
Correlating ion energies and CF2 surface production during fluorocarbon plasma processing of silicon
NASA Astrophysics Data System (ADS)
Martin, Ina T.; Zhou, Jie; Fisher, Ellen R.
2006-07-01
Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C3F8 and C4F8 plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29to92eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resulted in increased ion intensities and mean ion energies. Most significantly, a comparison to CF2 surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF2 surface production in these systems.
NASA Astrophysics Data System (ADS)
Murumkar, A. R.; Gupta, S.; Kaurwar, A.; Satankar, R. K.; Mounish, N. K.; Pitta, D. S.; Virat, J.; Kumar, G.; Hatte, S.; Tripathi, R. S.; Shedekar, V.; George, K. J.; Plappally, A. K.
2015-12-01
In India, the present value of water, both potable and not potable, bears no relation to the energy of water production. However, electrical energy spent on ground water extraction alone is equivalent to the nation's hydroelectric capacity of 40.1 GWh. Likewise, desalinating 1m3 water of the Bay of Bengal would save three times the energy for potable ground water extraction along the coast of the Bay. It is estimated that every second woman in rural India expends 0.98 kWhe/m3/d for bringing water for household needs. Yet, the water-energy nexus remains to be a topic which is gravely ignored. This is largely caused by factors such as lack of awareness, defective public policies, and intrusive cultural practices. Furthermore, there are instances of unceasing dereliction towards water management and maintenance of the sparsely distributed water and waste water treatment plants across the country. This pollutes the local water across India apart from other geogenic impurities. Additionally, product aesthetics and deceptive advertisements take advantage of the abulia generated by users' ignorance of technical specifications of water technologies and processes in mismanagement of water use. Accordingly, urban residents are tempted to expend on energy intensive water technologies at end use. This worsens the water-energy equation at urban households. Cooking procedures play a significant role in determining the energy expended on water at households. The paper also evaluates total energy expense involved in cultivating some major Kharif and Rabi crops. Manual and traditional agricultural practices are more prominent than mechanized and novel agricultural techniques. The specific energy consumption estimate for different water technologies will help optimize energy expended on water in its life cycles. The implication of the present study of water-energy correlation will help plan and extend water management infrastructure at different locations across India.
Stress formulation in the all-electron full-potential linearized augmented plane wave method
NASA Astrophysics Data System (ADS)
Nagasako, Naoyuki; Oguchi, Tamio
2012-02-01
Stress formulation in the linearlized augmented plane wave (LAPW) method has been proposed in 2002 [1] as an extension of the force formulation in the LAPW method [2]. However, pressure calculations only for Al and Si were reported in Ref.[1] and even now stress calculations have not yet been fully established in the LAPW method. In order to make it possible to efficiently relax lattice shape and atomic positions simultaneously and to precisely evaluate the elastic constants in the LAPW method, we reformulate stress formula in the LAPW method with the Soler-Williams representation [3]. Validity of the formulation is tested by comparing the pressure obtained as the trace of stress tensor with that estimated from total energies for a wide variety of material systems. Results show that pressure is estimated within the accuracy of less than 0.1 GPa. Calculations of the shear elastic constant show that the shear components of the stress tensor are also precisely computed with the present formulation [4].[4pt] [1] T. Thonhauser et al., Solid State Commun. 124, 275 (2002).[0pt] [2] R. Yu et al., Phys. Rev. B 43, 6411 (1991).[0pt] [3] J. M. Soler and A. R. Williams, Phys. Rev. B 40, 1560 (1989).[0pt] [4] N. Nagasako and T. Oguchi, J. Phys. Soc. Jpn. 80, 024701 (2011).
All-electron GW quasiparticle band structures of group 14 nitride compounds
NASA Astrophysics Data System (ADS)
Chu, Iek-Heng; Kozhevnikov, Anton; Schulthess, Thomas C.; Cheng, Hai-Ping
2014-07-01
We have investigated the group 14 nitrides (M3N4) in the spinel phase (γ-M3N4 with M = C, Si, Ge, and Sn) and β phase (β-M3N4 with M = Si, Ge, and Sn) using density functional theory with the local density approximation and the GW approximation. The Kohn-Sham energies of these systems have been first calculated within the framework of full-potential linearized augmented plane waves (LAPW) and then corrected using single-shot G0W0 calculations, which we have implemented in the modified version of the Elk full-potential LAPW code. Direct band gaps at the Γ point have been found for spinel-type nitrides γ-M3N4 with M = Si, Ge, and Sn. The corresponding GW-corrected band gaps agree with experiment. We have also found that the GW calculations with and without the plasmon-pole approximation give very similar results, even when the system contains semi-core d electrons. These spinel-type nitrides are novel materials for potential optoelectronic applications because of their direct and tunable band gaps.
All-electron GW quasiparticle band structures of group 14 nitride compounds
Chu, Iek-Heng; Cheng, Hai-Ping; Kozhevnikov, Anton; Schulthess, Thomas C.
2014-07-28
We have investigated the group 14 nitrides (M{sub 3}N{sub 4}) in the spinel phase (γ-M{sub 3}N{sub 4} with M = C, Si, Ge, and Sn) and β phase (β-M{sub 3}N{sub 4} with M = Si, Ge, and Sn) using density functional theory with the local density approximation and the GW approximation. The Kohn-Sham energies of these systems have been first calculated within the framework of full-potential linearized augmented plane waves (LAPW) and then corrected using single-shot G{sub 0}W{sub 0} calculations, which we have implemented in the modified version of the Elk full-potential LAPW code. Direct band gaps at the Γ point have been found for spinel-type nitrides γ-M{sub 3}N{sub 4} with M = Si, Ge, and Sn. The corresponding GW-corrected band gaps agree with experiment. We have also found that the GW calculations with and without the plasmon-pole approximation give very similar results, even when the system contains semi-core d electrons. These spinel-type nitrides are novel materials for potential optoelectronic applications because of their direct and tunable band gaps.
Gozem, Samer; Huntress, Mark; Schapiro, Igor; Lindh, Roland; Granovsky, Alexander A; Angeli, Celestino; Olivucci, Massimo
2012-11-13
The ground state potential energy surface of the retinal chromophore of visual pigments (e.g., bovine rhodopsin) features a low-lying conical intersection surrounded by regions with variable charge-transfer and diradical electronic structures. This implies that dynamic electron correlation may have a large effect on the shape of the force fields driving its reactivity. To investigate this effect, we focus on mapping the potential energy for three paths located along the ground state CASSCF potential energy surface of the penta-2,4-dieniminium cation taken as a minimal model of the retinal chromophore. The first path spans the bond length alternation coordinate and intercepts a conical intersection point. The other two are minimum energy paths along two distinct but kinetically competitive thermal isomerization coordinates. We show that the effect of introducing the missing dynamic electron correlation variationally (with MRCISD) and perturbatively (with the CASPT2, NEVPT2, and XMCQDPT2 methods) leads, invariably, to a stabilization of the regions with charge transfer character and to a significant reshaping of the reference CASSCF potential energy surface and suggesting a change in the dominating isomerization mechanism. The possible impact of such a correction on the photoisomerization of the retinal chromophore is discussed.
NASA Astrophysics Data System (ADS)
Cornaton, Yann; Stoyanova, Alexandrina; Jensen, Hans Jørgen Aa.; Fromager, Emmanuel
2013-08-01
An alternative separation of short-range exchange and correlation energies is used in the framework of second-order range-separated density-functional perturbation theory. This alternative separation was initially proposed by Toulouse [Theor. Chem. Acc.TCACFW1432-881X10.1007/s00214-005-0688-2 114, 305 (2005)] and relies on a long-range-interacting wave function instead of the noninteracting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hybrid (RSDH) type of functional, RSDHf, where “f” stands for “full-range integrals” as the regular full-range interaction appears explicitly in the energy expression when expanded in perturbation theory. In contrast to the usual RSDH functionals, RSDHf describes the coupling between long- and short-range correlations as an orbital-dependent contribution. Calculations on the first four noble-gas dimers show that this coupling has a significant effect on the potential energy curves in the equilibrium region, improving the accuracy of binding energies and equilibrium bond distances when second-order perturbation theory is appropriate.
NASA Astrophysics Data System (ADS)
Fantz, U.; Friedl, R.; Briefi, S.
2015-05-01
The visual properties of a large plasmoid rising from a water container into the air for up to 450 ms are brought into correlation with the total energy dissipated into the system, and, in particular, with the energy used for plasma generation. The latter parameters are deduced from the time-resolved discharge current and voltage of the capacitor bank which is used as energy supply. By varying the experimental parameters, the energy dissipated to the system varies between 5 kJ and 30 kJ from which 10% to 30% is transferred to the plasma. Clear correlations are obtained for the size of the plasmoid changing from 15 cm to 35 cm in width, the ascent velocity ranging from 1 m/s to 2 m/s, and the rising height for which up to 85 cm is measured. For the relation of the autonomous phase with the energy transferred to the plasma, two trends are observed: 450 ms duration is achieved in maximum with the present setup being almost independent on the electrode gap, the voltage-on time, the water conductivity, or the type of salt dissolved in the water. On the other hand, an almost linear dependence is obtained by changing the capacitance.
Millis, Richard M; Austin, Rachel E; Hatcher, Mark D; Bond, Vernon; Goring, Kim L
2011-01-01
We studied healthy males challenged with a 900 Cal test beverage and correlated EE with the raw (ms(2)) and normalized units (nu) of total power (TP), low frequency/high frequency (LF/HF) and VLF spectral power of heart rate variability (HRV). The correlations were evaluated during 20 min of normal breathing (NB, control) and 20 min of paced breathing (PB) at 12 breaths·min(-1) (0.2 Hz). EE was not significantly correlated with any of the HRV variables before the metabolic challenge. After the challenge, EE was positively correlated with LF/HF and with VLF; VLF was also positively correlated with LF/HF during both NB and PB. These findings suggest that EE may be a correlate of LF/HF and of VLF spectral power of HRV in healthy adolescent/young adult males. The association of lower resting energy expenditure with lower amounts of VLF spectral power may occur in individuals with predilections for obese phenotypes.
Energy deposition of heavy ions in the regime of strong beam-plasma correlations.
Gericke, D O; Schlanges, M
2003-03-01
The energy loss of highly charged ions in dense plasmas is investigated. The applied model includes strong beam-plasma correlation via a quantum T-matrix treatment of the cross sections. Dynamic screening effects are modeled by using a Debye-like potential with a velocity dependent screening length that guarantees the known low and high beam velocity limits. It is shown that this phenomenological model is in good agreement with simulation data up to very high beam-plasma coupling. An analysis of the stopping process shows considerably longer ranges and a less localized energy deposition if strong coupling is treated properly.
Correlation of the highest energy cosmic rays with nearby extragalactic objects
Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez, C.; Alvarez-Muniz, J.; Ambrosio, M.; /Balseiro Inst., San Carlos de Bariloche /Buenos Aires, CONICET /CNEA, Buenos Aires /Pierre Auger Observ. /La Plata U. /Natl. Tech. U., San Rafael /Adelaide U. /Catholic U. of Bolivia, La Paz /Bolivia U. /Rio de Janeiro, CBPF /Sao Paulo U.
2007-11-01
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrate that there is a correlation between the arrival directions of cosmic rays with energy above {approx} 6 x 10{sup 19} eV and the positions of active galactic nuclei (AGN) lying within {approx} 75 Mpc. We reject the hypothesis of an isotropic distribution of these cosmic rays at over 99% confidence level from a prescribed a priori test. The correlation we observe is compatible with the hypothesis that the highest energy particles originate from nearby extragalactic sources whose flux has not been significantly reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.
Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects
NASA Astrophysics Data System (ADS)
Pierre Auger Collaboration; Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez, C.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Argirò, S.; Arisaka, K.; Armengaud, E.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Atulugama, B. S.; Aublin, J.; Ave, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Barbosa, A. F.; Barnhill, D.; Barroso, S. L. C.; Bauleo, P.; Beatty, J.; Beau, T.; Becker, B. R.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bergmann, T.; Bernardini, P.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blasi, P.; Bleve, C.; Blümer, H.; Bohácová, M.; Bonifazi, C.; Bonino, R.; Boratav, M.; Brack, J.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Busca, N. G.; Caballero-Mora, K. S.; Cai, B.; Camin, D. V.; Caruso, R.; Carvalho, W.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazón-Boado, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chye, J.; Clark, P. D. J.; Clay, R. W.; Colombo, E.; Conceição, R.; Connolly, B.; Contreras, F.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Cronin, J.; Dagoret-Campagne, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; Di Giulio, C.; Diaz, J. C.; Dobrigkeit, C.; D'Olivo, J. C.; Dornic, D.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; DuVernois, M. A.; Engel, R.; Epele, L.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fernández, A.; Ferrer, F.; Ferry, S.; Fick, B.; Filevich, A.; Filipcic, A.; Fleck, I.; Fonte, R.; Fracchiolla, C. E.; Fulgione, W.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Geenen, H.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Herrero, R.; Gonçalves, P.; Gonçalves do Amaral, M.; Gonzalez, D.; Gonzalez, J. G.; González, M.; Góra, D.; Gorgi, A.; Gouffon, P.; Grassi, V.; Grillo, A.; Grunfeld, C.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Hamilton, J. C.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hauschildt, T.; Healy, M. D.; Hebbeker, T.; Heck, D.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J.; Horneffer, A.; Horvat, M.; Hrabovsky, M.; Huege, T.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Kaducak, M.; Kampert, K. H.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Kopmann, A.; Krieger, A.; Krömer, O.; Kümpel, D.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lebrun, D.; Le Brun, P.; Lee, J.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Leuthold, M.; Lhenry-Yvon, I.; López, R.; Lopez Agüera, A.; Lozano Bahilo, J.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Malek, M.; Mancarella, G.; Manceñido, M. E.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Martello, D.; Martínez, J.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McCauley, T.; McEwen, M.; McNeil, R. R.; Medina, M. C.; Medina-Tanco, G.; Meli, A.; Melo, D.; Menichetti, E.; Menschikov, A.; Meurer, Chr.; Meyhandan, R.; Micheletti, M. I.; Miele, G.; Miller, W.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafá, M.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Nellen, L.; Newman-Holmes, C.; Newton, D.; Nguyen Thi, T.; Nierstenhöfer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Oehlschläger, J.; Ohnuki, T.; Olinto, A.; Olmos-Gilbaja, V. M.; Ortiz, M.; Ostapchenko, S.; Otero, L.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Pastor, S.; Patel, M.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Pçkala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petrera, S.; Petrinca, P.; Petrov, Y.; Ngoc, DiepPham; Ngoc, DongPham; Pham Thi, T. N.; Pichel, A.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pinto, T.; Pirronello, V.; Pisanti, O.; Platino, M.; Pochon, J.; Porter, T. A.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Reucroft, S.; Revenu, B.; Rezende, F. A. S.; Rídky, J.; Riggi, S.; Risse, M.; Rivière, C.; Rizi, V.; Roberts, M.; Robledo, C.; Rodriguez, G.; Rodríguez Frías, D.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Ros, G.; Rosado, J.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scherini, V.; Schieler, H.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schovánek, P.; Schüssler, F.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Semikoz, D.; Settimo, M.; Shellard, R. C.; Sidelnik, I.; Siffert, B. B.; Sigl, G.; Smetniansky De Grande, N.; Smialkowski, A.; Smída, R.; Smith, A. G. K.; Smith, B. E.; Snow, G. R.; Sokolsky, P.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Takahashi, J.; Tamashiro, A.; Tamburro, A.; Tascau, O.; Tcaciuc, R.; Thomas, D.; Ticona, R.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Torresi, D.; Travnicek, P.; Tripathi, A.; Tristram, G.; Tscherniakhovski, D.; Tueros, M.; Tunnicliffe, V.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; van Elewyck, V.; Vázquez, R. A.; Veberic, D.; Veiga, A.; Velarde, A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Waldenmaier, T.; Walker, P.; Warner, D.; Watson, A. A.; Westerhoff, S.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Wileman, C.; Winnick, M. G.; Wu, H.; Wundheiler, B.; Xu, J.; Yamamoto, T.; Younk, P.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zech, A.; Zepeda, A.; Ziolkowski, M.
2007-11-01
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 × 1019 electron volts and the positions of active galactic nuclei (AGN) lying within ~75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.
Correlation of the highest-energy cosmic rays with nearby extragalactic objects.
Abraham, J; Abreu, P; Aglietta, M; Aguirre, C; Allard, D; Allekotte, I; Allen, J; Allison, P; Alvarez, C; Alvarez-Muñiz, J; Ambrosio, M; Anchordoqui, L; Andringa, S; Anzalone, A; Aramo, C; Argirò, S; Arisaka, K; Armengaud, E; Arneodo, F; Arqueros, F; Asch, T; Asorey, H; Assis, P; Atulugama, B S; Aublin, J; Ave, M; Avila, G; Bäcker, T; Badagnani, D; Barbosa, A F; Barnhill, D; Barroso, S L C; Bauleo, P; Beatty, J; Beau, T; Becker, B R; Becker, K H; Bellido, J A; Benzvi, S; Berat, C; Bergmann, T; Bernardini, P; Bertou, X; Biermann, P L; Billoir, P; Blanch-Bigas, O; Blanco, F; Blasi, P; Bleve, C; Blümer, H; Bohácová, M; Bonifazi, C; Bonino, R; Boratav, M; Brack, J; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Busca, N G; Caballero-Mora, K S; Cai, B; Camin, D V; Caruso, R; Carvalho, W; Castellina, A; Catalano, O; Cataldi, G; Cazón-Boado, L; Cester, R; Chauvin, J; Chiavassa, A; Chinellato, J A; Chou, A; Chye, J; Clark, P D J; Clay, R W; Colombo, E; Conceição, R; Connolly, B; Contreras, F; Coppens, J; Cordier, A; Cotti, U; Coutu, S; Covault, C E; Creusot, A; Cronin, J; Dagoret-Campagne, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Donato, C; de Jong, S J; De La Vega, G; de Mello Junior, W J M; de Mello Neto, J R T; De Mitri, I; de Souza, V; Del Peral, L; Deligny, O; Selva, A Della; Fratte, C Delle; Dembinski, H; Di Giulio, C; Diaz, J C; Dobrigkeit, C; D'Olivo, J C; Dornic, D; Dorofeev, A; Dos Anjos, J C; Dova, M T; D'Urso, D; Duvernois, M A; Engel, R; Epele, L; Erdmann, M; Escobar, C O; Etchegoyen, A; Facal San Luis, P; Falcke, H; Farrar, G; Fauth, A C; Fazzini, N; Fernández, A; Ferrer, F; Ferry, S; Fick, B; Filevich, A; Filipcic, A; Fleck, I; Fonte, R; Fracchiolla, C E; Fulgione, W; García, B; García Gámez, D; Garcia-Pinto, D; Garrido, X; Geenen, H; Gelmini, G; Gemmeke, H; Ghia, P L; Giller, M; Glass, H; Gold, M S; Golup, G; Albarracin, F Gomez; Berisso, M Gómez; Herrero, R Gómez; Gonçalves, P; Gonçalves do Amaral, M; Gonzalez, D; Gonzalez, J G; González, M; Góra, D; Gorgi, A; Gouffon, P; Grassi, V; Grillo, A; Grunfeld, C; Guardincerri, Y; Guarino, F; Guedes, G P; Gutiérrez, J; Hague, J D; Hamilton, J C; Hansen, P; Harari, D; Harmsma, S; Harton, J L; Haungs, A; Hauschildt, T; Healy, M D; Hebbeker, T; Heck, D; Hojvat, C; Holmes, V C; Homola, P; Hörandel, J; Horneffer, A; Horvat, M; Hrabovsky, M; Huege, T; Iarlori, M; Insolia, A; Ionita, F; Italiano, A; Kaducak, M; Kampert, K H; Keilhauer, B; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapik, R; Knapp, J; Koang, D-H; Kopmann, A; Krieger, A; Krömer, O; Kümpel, D; Kunka, N; Kusenko, A; La Rosa, G; Lachaud, C; Lago, B L; Lebrun, D; Lebrun, P; Lee, J; Leigui de Oliveira, M A; Letessier-Selvon, A; Leuthold, M; Lhenry-Yvon, I; López, R; Lopez Agüera, A; Lozano Bahilo, J; Maccarone, M C; Macolino, C; Maldera, S; Malek, M; Mancarella, G; Manceñido, M E; Mandat, D; Mantsch, P; Mariazzi, A G; Maris, I C; Martello, D; Martínez, J; Martínez Bravo, O; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurizio, D; Mazur, P O; McCauley, T; McEwen, M; McNeil, R R; Medina, M C; Medina-Tanco, G; Meli, A; Melo, D; Menichetti, E; Menschikov, A; Meurer, Chr; Meyhandan, R; Micheletti, M I; Miele, G; Miller, W; Mollerach, S; Monasor, M; Monnier Ragaigne, D; Montanet, F; Morales, B; Morello, C; Moreno, E; Moreno, J C; Morris, C; Mostafá, M; Muller, M A; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Nellen, L; Newman-Holmes, C; Newton, D; Thi, T Nguyen; Nierstenhöfer, N; Nitz, D; Nosek, D; Nozka, L; Oehlschläger, J; Ohnuki, T; Olinto, A; Olmos-Gilbaja, V M; Ortiz, M; Ostapchenko, S; Otero, L; Pakk Selmi-Dei, D; Palatka, M; Pallotta, J; Parente, G; Parizot, E; Parlati, S; Pastor, S; Patel, M; Paul, T; Pavlidou, V; Payet, K; Pech, M; Pekala, J; Pelayo, R; Pepe, I M; Perrone, L; Petrera, S; Petrinca, P; Petrov, Y; Ngoc, Dieppham; Ngoc, Dongpham; Pham Thi, T N; Pichel, A; Piegaia, R; Pierog, T; Pimenta, M; Pinto, T; Pirronello, V; Pisanti, O; Platino, M; Pochon, J; Porter, T A; Privitera, P; Prouza, M; Quel, E J; Rautenberg, J; Reucroft, S; Revenu, B; Rezende, F A S; Rídky, J; Riggi, S; Risse, M; Rivière, C; Rizi, V; Roberts, M; Robledo, C; Rodriguez, G; Rodríguez Frías, D; Rodriguez Martino, J; Rodriguez Rojo, J; Rodriguez-Cabo, I; Ros, G; Rosado, J; Roth, M; Rouillé-d'Orfeuil, B; Roulet, E; Rovero, A C; Salamida, F; Salazar, H; Salina, G; Sánchez, F; Santander, M; Santo, C E; Santos, E M; Sarazin, F; Sarkar, S; Sato, R; Scherini, V; Schieler, H; Schmidt, F; Schmidt, T; Scholten, O; Schovánek, P; Schüssler, F; Sciutto, S J; Scuderi, M; Segreto, A; Semikoz, D; Settimo, M; Shellard, R C; Sidelnik, I; Siffert, B B; Sigl, G; De Grande, N Smetniansky; Smialkowski, A; Smída, R; Smith, A G K; Smith, B E; Snow, G R; Sokolsky, P; Sommers, P; Sorokin, J; Spinka, H
2007-11-09
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.
Diagnosing collisionless energy transfer using field-particle correlations: Vlasov-Poisson plasmas
NASA Astrophysics Data System (ADS)
Howes, Gregory G.; Klein, Kristopher G.; Li, Tak Chu
2017-02-01
Turbulence plays a key role in the conversion of the energy of large-scale fields and flows to plasma heat, impacting the macroscopic evolution of the heliosphere and other astrophysical plasma systems. Although we have long been able to make direct spacecraft measurements of all aspects of the electromagnetic field and plasma fluctuations in near-Earth space, our understanding of the physical mechanisms responsible for the damping of the turbulent fluctuations in heliospheric plasmas remains incomplete. Here we propose an innovative field-particle correlation technique that can be used to measure directly the secular energy transfer from fields to particles associated with collisionless damping of the turbulent fluctuations. Furthermore, this novel procedure yields information about the collisionless energy transfer as a function of particle velocity, providing vital new information that can help to identify the dominant collisionless mechanism governing the damping of the turbulent fluctuations. Kinetic plasma theory is used to devise the appropriate correlation to diagnose Landau damping, and the field-particle correlation technique is thoroughly illustrated using the simplified case of the Landau damping of Langmuir waves in a 1D-1V (one dimension in physical space and one dimension in velocity space) Vlasov-Poisson plasma. Generalizations necessary to apply the field-particle correlation technique to diagnose the collisionless damping of turbulent fluctuations in the solar wind are discussed, highlighting several caveats. This novel field-particle correlation technique is intended to be used as a primary analysis tool for measurements from current, upcoming and proposed spacecraft missions that are focused on the kinetic microphysics of weakly collisional heliospheric plasmas, including the Magnetospheric Multiscale (MMS), Solar Probe Plus, Solar Orbiter and Turbulence Heating ObserveR (THOR) missions.
Karsch, F.; Kojo, T.; Mukherjee, S.; Stephanov, M.; Xu, N.
2011-10-27
Most of our visible universe is made up of hadronic matter. Quantum Chromodynamics (QCD) is the theory of strong interaction that describes the hadronic matter. However, QCD predicts that at high enough temperatures and/or densities ordinary hadronic matter ceases to exist and a new form of matter is created, the so-called Quark Gluon Plasma (QGP). Non-perturbative lattice QCD simulations shows that for high temperature and small densities the transition from the hadronic to the QCD matter is not an actual phase transition, rather it takes place via a rapid crossover. On the other hand, it is generally believed that at zero temperature and high densities such a transition is an actual first order phase transition. Thus, in the temperature-density phase diagram of QCD, the first order phase transition line emanating from the zero temperature high density region ends at some higher temperature where the transition becomes a crossover. The point at which the first order transition line turns into a crossover is a second order phase transition point belonging to three dimensional Ising universality class. This point is known as the QCD Critical End Point (CEP). For the last couple of years the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been performing experiments at lower energies in search of the elusive QCD CEP. In general critical behaviors are manifested through appearance of long range correlations and increasing fluctuations associated with the presence of mass-less modes in the vicinity of a second order phase transition. Experimental signatures of the CEP are likely to be found in observables related to fluctuations and correlations. Thus, one of the major focuses of the RHIC low energy scan program is to measure various experimental observables connected to fluctuations and correlations. On the other hand, with the start of the RHIC low energy scan program, a flurry of activities are taking place to provide solid theoretical
NASA Astrophysics Data System (ADS)
Gerrit Holzmann, Wolf
2002-10-01
Jet-production is predicted to play an important role in Heavy Ion Collisions at RHIC energies [1]. The identification and study of such jets can provide important insights on possible QGP formation at RHIC. Jet-topologies can lead to significant clustering of particles in phase space and hence, to significant enhancement in multi-particle correlations. Such correlations have been measured with the PHENIX detector. Multi-particle correlations obtained for charged hadrons in Au + Au collisions (sqrt(s) = 200 GeV/c) will be presented and compared to model predictions. Results will be shown for a broad range of pT and centrality selections. [1] M. Gyulassy and X.-N. Wang, Nucl. Phys. B420, 583 (1994) X.-N. Wang, M. Gyulassy and M. Pluemer, Phys. Rev. D 51, 3436 (1995)
On The Origin Of High Energy Correlations in Gamma-ray Bursts
Kocevski, Daniel
2012-04-03
I investigate the origin of the observed correlation between a gamma-ray burst's {nu}F{sub {nu}} spectral peak E{sub pk} and its isotropic equivalent energy E{sub iso} through the use of a population synthesis code to model the prompt gamma-ray emission from GRBs. By using prescriptions for the distribution of prompt spectral parameters as well as the population's luminosity function and co-moving rate density, I generate a simulated population of GRBs and examine how bursts of varying spectral properties and redshift would appear to a gamma-ray detector here on Earth. I find that a strong observed correlation can be produced between the source frame Epk and Eiso for the detected population despite the existence of only a weak and broad correlation in the original simulated population. The energy dependance of a gamma-ray detector's flux-limited detection threshold acts to produce a correlation between the source frame E{sub pk} and E{sub iso} for low luminosity GRBs, producing the left boundary of the observed correlation. Conversely, very luminous GRBs are found at higher redshifts than their low luminosity counterparts due to the standard Malquest bias, causing bursts in the low E{sub pk}, high E{sub iso} regime to go undetected because their E{sub pk} values would be redshifted to energies at which most gamma-ray detectors become less sensitive. I argue that it is this previously unexamined effect which produces the right boundary of the observed correlation. Therefore, the origin of the observed correlation is a complex combination of the instrument's detection threshold, the intrinsic cutoff in the GRB luminosity function, and the broad range of redshifts over which GRBs are detected. Although the GRB model presented here is a very simplified representation of the complex nature of GRBs, these simulations serve to demonstrate how selection effects caused by a combination of instrumental sensitivity and the cosmological nature of an astrophysical population
Peterson, K.A. ); Dunning, T.H. Jr. )
1995-02-01
The hydrogen bond energy and geometry of the HF dimer have been investigated using the series of correlation consistent basis sets from aug-cc-pVDZ to aug-cc-pVQZ and several theoretical methods including Moller--Plesset perturbation and coupled cluster theories. Estimates of the complete basis set (CBS) limit have been derived for the binding energy of (HF)[sub 2] at each level of theory by utilizing the regular convergence characteristics of the correlation consistent basis sets. CBS limit hydrogen bond energies of 3.72, 4.53, 4.55, and 4.60 kcal/mol are estimated at the SCF, MP2, MP4, and CCSD(T) levels of theory, respectively. CBS limits for the intermolecular F--F distance are estimated to be 2.82, 2.74, 2.73, and 2.73 A, respectively, for the same correlation methods. The effects of basis set superposition error (BSSE) on both the binding energies and structures have also been investigated for each basis set using the standard function counterpoise (CP) method. While BSSE has a negligible effect on the intramolecular geometries, the CP-corrected F--F distance and binding energy differ significantly from the uncorrected values for the aug-cc-pVDZ basis set; these differences decrease regularly with increasing basis set size, yielding the same limits in the CBS limit. Best estimates for the equilibrium properties of the HF dimer from CCSD(T) calculations are [ital D][sub [ital e
Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au +Au Collisions at RHIC
NASA Astrophysics Data System (ADS)
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration
2016-03-01
We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au +Au collisions for energies ranging from √{sN N }=7.7 to 200 GeV. The third harmonic v32{2 }=⟨cos 3 (ϕ1-ϕ2)⟩ , where ϕ1-ϕ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δ η =η1-η2 . Nonzero v32{2 } is directly related to the previously observed large-Δ η narrow-Δ ϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v32{2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v32{2 } is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v32{2 } for central collisions shows a minimum near √{sN N }=20 GeV .
NASA Astrophysics Data System (ADS)
Rezania, Hamed; Abdi, Ameneh
2017-04-01
We study the behaviors of both Hartree and correlation energies of undoped gapped armchair graphene nanoribbon using random phase approximation in the context of Hubbard model Hamiltonian. Specially, the effects of spin polarization and gap parameter on electron density dependence of Hartree and correlation energies of armchair graphene nanoribbon has been addressed. Our results show the variation of gap parameter leads to considerable effect on correlation and Hartree energy behavior of spin unpolarized gapped graphene in the middle electron density region. However local Hubbard interaction parameter affects the behaviors of Hartree and correlation energy on the whole range of electron density in zero magnetization case. We also show that a considerable reduction has been observed for density dependence of Hartree and correlation energies of spin polarized gapped graphene nanoribbon.
Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission
Lestone, J.P.
2016-01-15
A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of {sup 235}U and from spontaneous fission of {sup 252}Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.
Liu, Kexi; Lei, Yinkai; Wang, Guofeng
2013-11-28
Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O{sub 2} adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N{sub 4} chelation, as well as the molecular and electronic structures for the O{sub 2} adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O{sub 2} on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d{sub z{sup 2}}, d{sub xy}, d{sub xz}, and d{sub yz}) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O{sub 2} adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.
Liu, Kexi; Lei, Yinkai; Wang, Guofeng
2013-11-28
Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d(z(2)), d(xy), d(xz), and d(yz)) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.
Monte Carlo approach for hadron azimuthal correlations in high energy proton and nuclear collisions
NASA Astrophysics Data System (ADS)
Ayala, Alejandro; Dominguez, Isabel; Jalilian-Marian, Jamal; Magnin, J.; Tejeda-Yeomans, Maria Elena
2012-09-01
We use a Monte Carlo approach to study hadron azimuthal angular correlations in high-energy proton-proton and central nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider energies at midrapidity. We build a hadron event generator that incorporates the production of 2→2 and 2→3 parton processes and their evolution into hadron states. For nucleus-nucleus collisions we include the effect of parton energy loss in the quark-gluon plasma using a modified fragmentation function approach. In the presence of the medium, for the case when three partons are produced in the hard scattering, we analyze the Monte Carlo sample in parton and hadron momentum bins to reconstruct the angular correlations. We characterize this sample by the number of partons that are able to hadronize by fragmentation within the selected bins. In the nuclear environment the model allows hadronization by fragmentation only for partons with momentum above a threshold pTthresh=2.4 GeV. We argue that one should treat properly the effect of those partons with momentum below the threshold, because their interaction with the medium may lead to showers of low-momentum hadrons along the direction of motion of the original partons as the medium becomes diluted.
Gauthier, Charles; Campbell, Peter G C; Couture, Patrice
2011-09-01
Enzymes representing a variety of metabolic pathways were examined in yellow perch (Perca flavescens) collected from a metal-contaminated region (Rouyn-Noranda, Québec, Canada) to determine which were most closely related to fish condition factor, pyloric caeca weight, and visceral lipid accumulation, as well to seek a better understanding of the influence of metal contamination on the physiology and biometrics of perch. Compared to laboratory fish, wild perch were under important energy restrictions. The condition factor of wild fish was correlated with indicators of aerobic metabolism (citrate synthase, cytochrome C oxidase), protein anabolism (nucleoside diphosphokinase), and indicators of lipid accumulation (glucose-6-phosphate dehydrogenase, visceral lipid index). Pyloric caeca weights were well correlated with indicators of protein anabolism, but only when both seasons were examined together, possibly indicating a lag in the response of enzymes to changes in diet. The addition of contaminant stress to existing energy restrictions led to changes in the relationships between enzymes and biometrics, reducing the predictive power of the models for perch in contaminated lakes. The present study broadens our knowledge of the impact of metal contamination on energy accumulation and tissue metabolic capacities in wild perch.
LORENTZ-FACTOR-ISOTROPIC-LUMINOSITY/ENERGY CORRELATIONS OF GAMMA-RAY BURSTS AND THEIR INTERPRETATION
Lue Jing; Zou Yuanchuan; Lei Weihua; Wu Qingwen; Wang Dingxiong; Zhang Bing; Lue Houjun; Liang Enwei E-mail: leiwh@hust.edu.cn
2012-05-20
The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta ({Gamma}{sub 0}) is a key parameter to understanding GRB physics. Liang et al. have discovered a correlation between {Gamma}{sub 0} and isotropic {gamma}-ray energy: {Gamma}{sub 0}{proportional_to}E{sup 0.25}{sub {gamma},iso,52}. By including more GRBs with updated data and more methods to derive {Gamma}{sub 0}, we confirm this correlation and obtain {Gamma}{sub 0} {approx_equal} 91E{sup 0.29}{sub {gamma},iso,52}. Evaluating the mean isotropic {gamma}-ray luminosities L{sub {gamma},iso} of the GRBs in the same sample, we discover an even tighter correlation {Gamma}{sub 0} {approx_equal} 249L{sup 0.30}{sub {gamma},iso,52}. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive {Gamma}{sub 0}{proportional_to}L{sup 0.22}{sub {gamma},iso}, which is consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.
Energy-dependent correlations in the S-matrix of chaotic systems
NASA Astrophysics Data System (ADS)
Novaes, Marcel
2016-12-01
The M-dimensional unitary matrix S(E), which describes scattering of waves, is a strongly fluctuating function of the energy for complex systems such as ballistic cavities, whose geometry induces chaotic ray dynamics. Its statistical behaviour can be expressed by means of correlation functions of the kind <" separators=" S i j ( E + ɛ ) Sp q † ( E - ɛ ) > , which have been much studied within the random matrix approach. In this work, we consider correlations involving an arbitrary number of matrix elements and express them as infinite series in 1/M, whose coefficients are rational functions of ɛ. From a mathematical point of view, this may be seen as a generalization of the Weingarten functions of circular ensembles.
Exact Asymptotics of the Freezing Transition of a Logarithmically Correlated Random Energy Model
NASA Astrophysics Data System (ADS)
Webb, Christian
2011-12-01
We consider a logarithmically correlated random energy model, namely a model for directed polymers on a Cayley tree, which was introduced by Derrida and Spohn. We prove asymptotic properties of a generating function of the partition function of the model by studying a discrete time analogy of the KPP-equation—thus translating Bramson's work on the KPP-equation into a discrete time case. We also discuss connections to extreme value statistics of a branching random walk and a rescaled multiplicative cascade measure beyond the critical point.
Takahashi, Y.
2003-06-08
This report describes the research work performed under the support of the DOE research grant E-FG02-97ER4108. The work is composed of three parts: (1) Visual analysis and quality control of the Micro Vertex Detector (MVD) of the PHENIX experiments carried out of Brookhaven National Laboratory. (2) Continuation of the data analysis of the EMU05/09/16 experiments for the study of the inclusive particle production spectra and multi-particle correlation. (3) Exploration of a new statistical means to study very high-multiplicity of nuclear-particle ensembles and its perspectives to apply to the higher energy experiments.
Damage correlations in semiconductor devices exposed to gamma and high energy swift heavy ions
NASA Astrophysics Data System (ADS)
Pushpa, N.; Prakash, A. P. Gnana
2015-05-01
NPN rf power transistors and N-channel depletion MOSFETs are irradiated by different high energy swift heavy ions and 60Co gamma radiation in the dose range of 100 krad to 100 Mrad. The damage created by different heavy ions and 60Co gamma radiation in NPN rf power transistors and N-channel depletion MOSFETs have been correlated and studied in the same dose range. The recoveries in the electrical characteristics of different swift heavy ions and 60Co gamma irradiated devices have been studied after annihilation.
Doria, A; Gallerano, G P; Giovenale, E; Messina, G; Spassovsky, I
2004-12-31
We report the first observation of enhanced coherent emission of terahertz radiation in a compact free electron laser. A radio-frequency (rf) modulated electron beam is passed through a magnetic undulator emitting coherent radiation at harmonics of the rf with a phase which depends on the electron drift velocity. A proper correlation between the energy and phase distributions of the electrons in the bunch has been exploited to lock in phase the radiated field, resulting in over 1 order of magnitude enhancement of the coherent emission.
Damage correlations in semiconductor devices exposed to gamma and high energy swift heavy ions
Pushpa, N.; Prakash, A. P. Gnana
2015-05-15
NPN rf power transistors and N-channel depletion MOSFETs are irradiated by different high energy swift heavy ions and {sup 60}Co gamma radiation in the dose range of 100 krad to 100 Mrad. The damage created by different heavy ions and {sup 60}Co gamma radiation in NPN rf power transistors and N-channel depletion MOSFETs have been correlated and studied in the same dose range. The recoveries in the electrical characteristics of different swift heavy ions and {sup 60}Co gamma irradiated devices have been studied after annihilation.
Correlations between Energy and Displacement Demands for Performance-Based Seismic Engineering
NASA Astrophysics Data System (ADS)
Mollaioli, Fabrizio; Bruno, Silvia; Decanini, Luis; Saragoni, Rodolfo
2011-01-01
The development of a scientific framework for performance-based seismic engineering requires, among other steps, the evaluation of ground motion intensity measures at a site and the characterization of their relationship with suitable engineering demand parameters (EDPs) which describe the performance of a structure. In order to be able to predict the damage resulting from earthquake ground motions in a structural system, it is first necessary to properly identify ground motion parameters that are well correlated with structural response and, in turn, with damage. Since structural damage during an earthquake ground motion may be due to excessive deformation or to cumulative cyclic damage, reliable methods for estimating displacement demands on structures are needed. Even though the seismic performance is directly related to the global and local deformations of the structure, energy-based methodologies appear more helpful in concept, as they permit a rational assessment of the energy absorption and dissipation mechanisms that can be effectively accomplished to balance the energy imparted to the structure. Moreover, energy-based parameters are directly related to cycles of response of the structure and, therefore, they can implicitly capture the effect of ground motion duration, which is ignored by conventional spectral parameters. Therefore, the identification of reliable relationships between energy and displacement demands represents a fundamental issue in both the development of more reliable seismic code provisions and the evaluation of seismic vulnerability aimed at the upgrading of existing hazardous facilities. As these two aspects could become consistently integrated within a performance-based seismic design methodology, understanding how input and dissipated energy are correlated with displacement demands emerges as a decisive prerequisite. The aim of the present study is the establishment of functional relationships between input and dissipated energy
NASA Astrophysics Data System (ADS)
Pérez-Jordá, José M.; San-Fabián, Emilio; Moscardó, Federico
1992-04-01
The Kohn-Sham energy with exact exchange [using the exact Hartree-Fock (HF) exchange but an approximate correlation-energy functional] may be computed very accurately by adding the correlation obtained from the HF density to the total HF energy. Three density functionals are used: local spin density (LSD), LSD with self-interaction correction, and LSD with generalized gradient correction. This scheme has been extended (Lie-Clementi, Colle-Salvetti, and Moscardo-San-Fabian) to be used with general-valence-bond (GVB) energies and wave functions, so that the extra correlation included in the GVB energy is not counted again. The effect of all these approximate correlations on HF or GVB spectroscopic constants (Re,ωe, and De) is studied. Approximate relations showing how correlation affects them are derived, and may be summarized as follows: (1) the effect on Re and ωe depends only on the correlation derivative at Re, and (2) the effect on De depends mainly on the correlation difference between quasidissociated and equilibrium geometries. A consequence is that all the correlation corrections tested here give larger ωe and De and shorter Re than the uncorrected HF or GVB values. This trend is correct for De for both HF and GVB. For Re and ωe, it is correct in most cases for GVB, but it often fails for the HF cases. A comparison is made with Kohn-Sham calculations with both exchange and correlation approximated. As a final conclusion, it is found that, within the present scheme, a qualitatively correct HF or GVB potential-energy curve, together with a correlation-energy approximation with correct dissociation behavior, is crucial for obtaining good estimates of spectroscopic constants.
Rasi-Caldogno, Franca; De Michelis, Maria I.
1978-01-01
The influence of O2 availability on the rate of protein synthesis, the levels of RNA and of adenylates, and the value of the energy charge in squash (Cucurbita maxima) cotyledons isolated from seeds germinated for 15 or 28 hours at different O2 concentration (3% or 20% O2) has been investigated. The rate of protein synthesis is five times lower in cotyledons maintained in 3% O2 than in those maintained in 20% O2. Also net RNA synthesis is almost blocked in 3% O2, while in 20% O2 it proceeds almost linearly for 48 hours. The different RNA contents cannot explain the different rates of protein synthesis. The results of shift experiments (cotyledons shifted from 20% to 3% O2 or vice versa) show that the rate of protein synthesis is strictly correlated with actual O2 availability and is largely independent of the one in the previous period. O2 controls the development of the adenylate pool and particularly the increase of ATP level. Thus, both the adenylate pool and the values of the energy charge ratio are lower in cotyledons grown in 3% than in 20% O2. The shifts of O2 availability induce rapid changes of ATP, ADP, and AMP levels and thus of the values of the energy charge, which are about 0.7 at 3% O2 and higher than 0.8 at 20% O2, independent of previous O2 availability. The rate of protein synthesis appears to be largely independent of the levels of the single nucleotides and better correlated to the energy charge values. PMID:16660244
Nemmen, Rodrigo S.; Bonatto, Charles; Storchi-Bergmann, Thaisa
2010-10-10
We analyze the correlation of the positions of {gamma}-ray sources in the Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) and the First LAT Active Galactic Nuclei (AGNs) Catalog (1LAC) with the arrival directions of ultra-high-energy cosmic rays (UHECRs) observed with the Pierre Auger Observatory, in order to investigate the origin of UHECRs. We find that Galactic sources and blazars identified in the 1FGL are not significantly correlated with UHECRs, while the 1LAC sources display a mild correlation (2.6{sigma} level) on an {approx}2.{sup 0}4 angular scale. When selecting only the 1LAC AGNs closer than 200 Mpc, we find a strong association (5.4{sigma}) between their positions and the directions of UHECRs on an {approx}17{sup 0} angular scale; the probability of the observed configuration being due to an isotropic flux of cosmic rays is 5 x 10{sup -8}. There is also a 5{sigma} correlation with nearby 1LAC sources on a 6.{sup 0}5 scale. We identify seven '{gamma}-ray loud' AGNs which are associated with UHECRs within {approx}17{sup 0} and are likely candidates for the production sites of UHECRs: Centaurus A, NGC 4945, ESO 323-G77, 4C+04.77, NGC 1218, RX J0008.0+1450, and NGC 253. We interpret these results as providing additional support to the hypothesis of the origin of UHECRs in nearby extragalactic objects. As the angular scales of the correlations are large, we discuss the possibility that intervening magnetic fields might be considerably deflecting the trajectories of the particles on their way to Earth.
Highly correlated systems. Excitation energies of first row transition metals Sc-Cu
NASA Astrophysics Data System (ADS)
Raghavachari, Krishnan; Trucks, Gary W.
1989-07-01
The low-lying dns2→dn+1s1 excitation energies of the first row transition metal atoms Sc-Cu are calculated using fourth-order M≂ller-Plesset perturbation theory (MP4) as well as quadratic configuration interaction (QCI) techniques with large spd and spdf basis sets. The MP4 method performs well for Sc-Mn but fails dramatically for Fe-Cu. In contrast, the QCI technique performs uniformly for all excitation energies with a mean deviation from experiment of only 0.14 eV after including relativistic corrections. f functions contribute 0.1-0.4 eV to the excitation energies for these systems. The highly correlated d10 state of the Ni atom is also considered in detail. The QCI technique obtains the d9s1→d10 splitting of the Ni atom with an error of only 0.13 eV. The results show that single-configuration Hartree-Fock based methods can be successful in calculating excitation energies of transition metal atoms.
Highly correlated systems. Excitation energies of first row transition metals Sc--Cu
Raghavachari, K.; Trucks, G. W.
1989-07-15
The low-lying /ital d//sup /ital n/s//sup 2//r arrow//ital d//sup /ital n/+1//ital s//sup 1/ excitation energies of the first row transition metal atoms Sc--Cu are calculated using fourth-order M/congruent/ller--Plesset perturbation theory (MP4) as well as quadratic configuration interaction (QCI) techniques with large /ital spd/ and /ital spdf/ basis sets. The MP4 method performs well for Sc--Mn but fails dramatically for Fe--Cu. In contrast, the QCI technique performs uniformly for all excitation energies with a mean deviation from experiment of only 0.14 eV after including relativistic corrections. /ital f/ functions contribute 0.1--0.4 eV to the excitation energies for these systems. The highly correlated /ital d//sup 10/ state of the Ni atom is also considered in detail. The QCI technique obtains the /ital d//sup 9//ital s1//r arrow//ital d10/ splitting of the Ni atom with an error of only 0.13 eV. The results show that single-configuration Hartree--Fock based methods can be successful in calculating excitation energies of transition metal atoms.
NASA Astrophysics Data System (ADS)
Huo, Pengfei; Coker, David F.
2012-03-01
Two-dimensional photon-echo experiments indicate that excitation energy transfer between chromophores near the reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides occurs coherently with decoherence times of hundreds of femtoseconds, comparable to the energy transfer time scale in these systems. The original explanation of this observation suggested that correlated fluctuations in chromophore excitation energies, driven by large scale protein motions could result in long lived coherent energy transfer dynamics. However, no significant site energy correlation has been found in recent molecular dynamics simulations of several model light harvesting systems. Instead, there is evidence of correlated fluctuations in site energy-electronic coupling and electronic coupling-electronic coupling. The roles of these different types of correlations in excitation energy transfer dynamics are not yet thoroughly understood, though the effects of site energy correlations have been well studied. In this paper, we introduce several general models that can realistically describe the effects of various types of correlated fluctuations in chromophore properties and systematically study the behavior of these models using general methods for treating dissipative quantum dynamics in complex multi-chromophore systems. The effects of correlation between site energy and inter-site electronic couplings are explored in a two state model of excitation energy transfer between the accessory bacteriochlorophyll and bacteriopheophytin in a reaction center system and we find that these types of correlated fluctuations can enhance or suppress coherence and transfer rate simultaneously. In contrast, models for correlated fluctuations in chromophore excitation energies show enhanced coherent dynamics but necessarily show decrease in excitation energy transfer rate accompanying such coherence enhancement. Finally, for a three state model of the Fenna-Matthews-Olsen light
Explicit correlation treatment of the potential energy surface of CO2 dimer.
Kalugina, Yulia N; Buryak, Ilya A; Ajili, Yosra; Vigasin, Andrei A; Jaidane, Nejm Eddine; Hochlaf, Majdi
2014-06-21
We present an extensive study of the four-dimensional potential energy surface (4D-PES) of the carbon dioxide dimer, (CO2)2. This PES is developed over the set of intermolecular coordinates. The electronic computations are carried out at the explicitly correlated coupled cluster method with single, double, and perturbative triple excitations [CCSD(T)-F12] level of theory in connection with the augmented correlation-consistent aug-cc-pVTZ basis set. An analytic representation of the 4D-PES is derived. Our extensive calculations confirm that "Slipped Parallel" is the most stable form and that the T-shaped structure corresponds to a transition state. Later on, this PES is employed for the calculations of the vibrational energy levels of the dimer. Moreover, the temperature dependence of the dimer second virial coefficient and of the first spectral moment of rototranslational collision-induced absorption spectrum is derived. For both quantities, a good agreement is found between our values and the experimental data for a wide range of temperatures. This attests to the high quality of our PES. Generally, our PES and results can be used for modeling CO2 supercritical fluidity and examination of its role in planetary atmospheres. It can be also incorporated into dynamical computations of CO2 capture and sequestration. This allows deep understanding, at the microscopic level, of these processes.
Explicit correlation treatment of the potential energy surface of CO{sub 2} dimer
Kalugina, Yulia N.; Buryak, Ilya A.; Ajili, Yosra; Vigasin, Andrei A.; Jaidane, Nejm Eddine; Hochlaf, Majdi
2014-06-21
We present an extensive study of the four-dimensional potential energy surface (4D-PES) of the carbon dioxide dimer, (CO{sub 2}){sub 2}. This PES is developed over the set of intermolecular coordinates. The electronic computations are carried out at the explicitly correlated coupled cluster method with single, double, and perturbative triple excitations [CCSD(T)-F12] level of theory in connection with the augmented correlation-consistent aug-cc-pVTZ basis set. An analytic representation of the 4D-PES is derived. Our extensive calculations confirm that “Slipped Parallel” is the most stable form and that the T-shaped structure corresponds to a transition state. Later on, this PES is employed for the calculations of the vibrational energy levels of the dimer. Moreover, the temperature dependence of the dimer second virial coefficient and of the first spectral moment of rototranslational collision-induced absorption spectrum is derived. For both quantities, a good agreement is found between our values and the experimental data for a wide range of temperatures. This attests to the high quality of our PES. Generally, our PES and results can be used for modeling CO{sub 2} supercritical fluidity and examination of its role in planetary atmospheres. It can be also incorporated into dynamical computations of CO{sub 2} capture and sequestration. This allows deep understanding, at the microscopic level, of these processes.
Explicit correlation treatment of the potential energy surface of CO2 dimer
NASA Astrophysics Data System (ADS)
Kalugina, Yulia N.; Buryak, Ilya A.; Ajili, Yosra; Vigasin, Andrei A.; Jaidane, Nejm Eddine; Hochlaf, Majdi
2014-06-01
We present an extensive study of the four-dimensional potential energy surface (4D-PES) of the carbon dioxide dimer, (CO2)2. This PES is developed over the set of intermolecular coordinates. The electronic computations are carried out at the explicitly correlated coupled cluster method with single, double, and perturbative triple excitations [CCSD(T)-F12] level of theory in connection with the augmented correlation-consistent aug-cc-pVTZ basis set. An analytic representation of the 4D-PES is derived. Our extensive calculations confirm that "Slipped Parallel" is the most stable form and that the T-shaped structure corresponds to a transition state. Later on, this PES is employed for the calculations of the vibrational energy levels of the dimer. Moreover, the temperature dependence of the dimer second virial coefficient and of the first spectral moment of rototranslational collision-induced absorption spectrum is derived. For both quantities, a good agreement is found between our values and the experimental data for a wide range of temperatures. This attests to the high quality of our PES. Generally, our PES and results can be used for modeling CO2 supercritical fluidity and examination of its role in planetary atmospheres. It can be also incorporated into dynamical computations of CO2 capture and sequestration. This allows deep understanding, at the microscopic level, of these processes.
NASA Astrophysics Data System (ADS)
Lutz, Jesse J.; Piecuch, Piotr
2008-04-01
The recently proposed potential energy surface (PES) extrapolation scheme, which predicts smooth molecular PESs corresponding to larger basis sets from the relatively inexpensive calculations using smaller basis sets by scaling electron correlation energies [A.J.C. Varandas and P. Piecuch, Chem. Phys. Lett. 430,448 (2006)], is applied to the PESs associated with the conrotatory and disrotatory isomerization pathways of bicyclo[l.l.0]butane to buta-l,3-diene. The relevant electronic structure calculations are performed using the completely renormalized coupled-cluster method with singly and doubly excited clusters, and a non-iterative treatment of connected triply excited clusters, termed CR-CC(2,3). A comparison with the explicit CR-CC(2,3) calculations using the large correlation-consistent basis set of the cc-pVQZ quality shows that the cc-pVQZ PESs obtained by the extrapolation from the smaller basis set calculations employing the cc-pVDZ and cc-pVTZ basis sets are practically identical, to within fractions of a millihartree, to the true cc-pVQZ PESs. It is also demonstrated that one can use a similar extrapolation procedure to accurately predict the complete basis set (CBS) limits of the calculated PESs from the results of smaller basis set calculations at a fraction of the effort required by the conventional point-wise CBS extrapolations.
NASA Astrophysics Data System (ADS)
Lutz, Jesse J.; Piecuch, Piotr
2008-04-01
The recently proposed potential energy surface (PES) extrapolation scheme, which predicts smooth molecular PESs corresponding to larger basis sets from the relatively inexpensive calculations using smaller basis sets by scaling electron correlation energies [A. J. C. Varandas and P. Piecuch, Chem. Phys. Lett. 430, 448 (2006)], is applied to the PESs associated with the conrotatory and disrotatory isomerization pathways of bicyclo[1.1.0]butane to buta-1,3-diene. The relevant electronic structure calculations are performed using the completely renormalized coupled-cluster method with singly and doubly excited clusters and a noniterative treatment of connected triply excited clusters, termed CR-CC(2,3), which is known to provide a highly accurate description of chemical reaction profiles involving biradical transition states and intermediates. A comparison with the explicit CR-CC(2,3) calculations using the large correlation-consistent basis set of the cc-pVQZ quality shows that the cc-pVQZ PESs obtained by the extrapolation from the smaller basis set calculations employing the cc-pVDZ and cc-pVTZ basis sets are practically identical, to within fractions of a millihartree, to the true cc-pVQZ PESs. It is also demonstrated that one can use a similar extrapolation procedure to accurately predict the complete basis set (CBS) limits of the calculated PESs from the results of smaller basis set calculations at a fraction of the effort required by the conventional pointwise CBS extrapolations.
Lyons, G N; Halsey, L G; Pope, E C; Eddington, J D; Houghton, J D R
2013-10-01
How animals manage time and expend energy has implications for survivorship. Being able to measure key metabolic costs of animals under natural conditions is therefore an important tool in behavioral ecology. One method for estimating activity-specific metabolic rate is via derived measures of acceleration, often 'overall dynamic body acceleration' (ODBA), recorded by an instrumented acceleration logger. ODBA has been shown to correlate well with rate of oxygen consumption (V˙o2) in a range of species during activity in the laboratory. This study devised a method for attaching acceleration loggers to decapod crustaceans and then correlated ODBA against concurrent respirometry readings to assess accelerometry as a proxy for activity-specific energy expenditure in a model species, the American lobster Homarus americanus. Where the instrumented animals exhibited a sufficient range of activity levels, positive linear relationships were found between V˙o2 and ODBA over 20min periods at a range of ambient temperatures (6, 13 and 20°C). Mixed effect linear models based on these data and morphometrics provided reasonably strong predictive power for estimating activity-specific V˙o2 from ODBA. These V˙o2-ODBA calibrations demonstrate the potential of accelerometry as an effective predictor of behavior-specific metabolic rate of crustaceans in the wild during periods of activity.
Correlation of Thermally Induced Pores with Microstructural Features Using High Energy X-rays
NASA Astrophysics Data System (ADS)
Menasche, David B.; Shade, Paul A.; Lind, Jonathan; Li, Shiu Fai; Bernier, Joel V.; Kenesei, Peter; Schuren, Jay C.; Suter, Robert M.
2016-11-01
Combined application of a near-field High Energy Diffraction Microscopy measurement of crystal lattice orientation fields and a tomographic measurement of pore distributions in a sintered nickel-based superalloy sample allows pore locations to be correlated with microstructural features. Measurements were carried out at the Advanced Photon Source beamline 1-ID using an X-ray energy of 65 keV for each of the measurement modes. The nickel superalloy sample was prepared in such a way as to generate significant thermally induced porosity. A three-dimensionally resolved orientation map is directly overlaid with the tomographically determined pore map through a careful registration procedure. The data are shown to reliably reproduce the expected correlations between specific microstructural features (triple lines and quadruple nodes) and pore positions. With the statistics afforded by the 3D data set, we conclude that within statistical limits, pore formation does not depend on the relative orientations of the grains. The experimental procedures and analysis tools illustrated are being applied to a variety of materials problems in which local heterogeneities can affect materials properties.
Resummation of threshold, low- and high-energy expansions for heavy-quark correlators
Greynat, David; Peris, Santiago
2010-08-01
With the help of the Mellin-Barnes transform, we show how to simultaneously resum the expansion of a heavy-quark correlator around q{sup 2}=0 (low-energy), q{sup 2}=4m{sup 2} (threshold, where m is the quark mass), and q{sup 2}{yields}-{infinity} (high-energy) in a systematic way. We exemplify the method for the perturbative vector correlator at O({alpha}{sub s}{sup 2}) and O({alpha}{sub s}{sup 3}). We show that the coefficients, {Omega}(n), of the Taylor expansion of the vacuum polarization function in terms of the conformal variable {omega} admit, for large n, an expansion in powers of 1/n (up to logarithms of n) that we can calculate exactly. This large-n expansion has a sign-alternating component given by the logarithms of the operator-product expansion, and a fixed-sign component given by the logarithms of the threshold expansion in the external momentum q{sup 2}.
Squeezed K{sup +}K{sup -} correlations in high energy heavy ion collisions
Dudek, Danuce M.; Padula, Sandra S.
2010-09-15
The hot and dense medium formed in high energy heavy ion collisions may modify some hadronic properties. In particular, if hadron masses are shifted in-medium, it was demonstrated that this could lead to back-to-back squeezed correlations (BBC) of particle-antiparticle pairs. Although well-established theoretically, the squeezed correlations have not yet been discovered experimentally. A method has been suggested for the empirical search of this effect, which was previously illustrated for {phi}{phi} pairs. We apply here the formalism and the suggested method to the case of K{sup +}K{sup -} pairs, since they may be easier to identify experimentally. The time distribution of the emission process plays a crucial role in the survival of the BBC's. We analyze the cases where the emission is supposed to occur suddenly or via a Lorentzian distribution, and compare with the case of a Levy distribution in time. Effects of squeezing on the correlation function of identical particles are also analyzed.
Bharadwaj, Atul S; Singh, Swarn L; Singh, Yashwant
2013-08-01
A free-energy functional for a crystal that contains both the symmetry-conserved and symmetry-broken parts of the direct pair-correlation function has been used to investigate the crystallization of fluids in three dimensions. The symmetry-broken part of the direct pair-correlation function has been calculated using a series in ascending powers of the order parameters and which contains three- and higher-body direct correlation functions of the isotropic phase. It is shown that a very accurate description of freezing transitions for a wide class of potentials is found by considering the first two terms of this series. The results found for freezing parameters including the structure of the frozen phase for fluids interacting via the inverse power potential u(r)=ε(σ/r)(n) for n ranging from 4 to ∞ are in very good agreement with simulation results. It is found that for n>6.5 the fluid freezes into a face-centered cubic (fcc) structure while for n≤6 the body-centered cubic (bcc) structure is preferred. The fluid-bcc-fcc triple point is found to be at 1/n=0.158, which is in good agreement with simulation result.
Pressure-energy correlations in liquids. V. Isomorphs in generalized Lennard-Jones systems.
Schrøder, Thomas B; Gnan, Nicoletta; Pedersen, Ulf R; Bailey, Nicholas P; Dyre, Jeppe C
2011-04-28
This series of papers is devoted to identifying and explaining the properties of strongly correlating liquids, i.e., liquids with more than 90% correlation between their virial W and potential energy U fluctuations in the NVT ensemble. Paper IV [N. Gnan et al., J. Chem. Phys. 131, 234504 (2009)] showed that strongly correlating liquids have "isomorphs," which are curves in the phase diagram along which structure, dynamics, and some thermodynamic properties are invariant in reduced units. In the present paper, using the fact that reduced-unit radial distribution functions are isomorph invariant, we derive an expression for the shapes of isomorphs in the WU phase diagram of generalized Lennard-Jones systems of one or more types of particles. The isomorph shape depends only on the Lennard-Jones exponents; thus all isomorphs of standard Lennard-Jones systems (with exponents 12 and 6) can be scaled onto a single curve. Two applications are given. One tests the prediction that the solid-liquid coexistence curve follows an isomorph by comparing to recent simulations by Ahmed and Sadus [J. Chem. Phys. 131, 174504 (2009)]. Excellent agreement is found on the liquid side of the coexistence curve, whereas the agreement is less convincing on the solid side. A second application is the derivation of an approximate equation of state for generalized Lennard-Jones systems by combining the isomorph theory with the Rosenfeld-Tarazona expression for the temperature dependence of the potential energy on isochores. It is shown that the new equation of state agrees well with simulations.
Core-core and core-valence correlation energy atomic and molecular benchmarks for Li through Ar
Ranasinghe, Duminda S.; Frisch, Michael J.; Petersson, George A.
2015-12-07
We have established benchmark core-core, core-valence, and valence-valence absolute coupled-cluster single double (triple) correlation energies (±0.1%) for 210 species covering the first- and second-rows of the periodic table. These species provide 194 energy differences (±0.03 mE{sub h}) including ionization potentials, electron affinities, and total atomization energies. These results can be used for calibration of less expensive methodologies for practical routine determination of core-core and core-valence correlation energies.
Perichart-Perera, Otilia; Balas-Nakash, Margie; Rodríguez-Cano, Ameyalli; Muñoz-Manrique, Cinthya; Monge-Urrea, Adriana; Vadillo-Ortega, Felipe
2010-02-01
Dietary and lifestyle changes in Mexico have been linked to an increase in chronic diseases such as obesity and cardiovascular disease. Important dietary changes such as an increase in the consumption of energy-dense foods (high in oils, animal or processed fats, and sugars) have been recently reported. The objective of this study was to identify how key dietary energy sources correlated with other indexes of cardiovascular disease in a Mexican school-age population. From 2004 to 2006, a convenience sample (n=228) of 9- to 13-year-olds, 48.2% girls and 51.8% boys, from three public urban schools were included. Anthropometric, blood pressure, and dietary assessment (two multiple pass 24-hour recalls) were done. More than half of children did not meet the fruit and vegetable recommended intake. High-fat dairy foods (14% of total energy intake), refined carbohydrates (13.5%), red/processed meat (8.5%), added sugars/desserts (7%), corn tortilla (6.5%), and soft drinks/sweetened beverages (5%) were the highest dietary energy sources consumed. In a subgroup of children (n=185), a fasting blood sample was collected for biochemical analysis. A positive association was observed between glucose and diastolic blood pressure with the intake of soft drinks/sweetened beverages, insulin concentrations and the intake of white bread, and triglyceride concentrations with the intake of added fats. Unhealthful dietary energy sources are frequently consumed by these children. Culturally competent nutrition counseling should be offered to Mexican-American children and their families with a significant risk of cardiovascular disease. Efforts should be made to design and implement nutrition education and health promotion strategies in schools.
Inelastic cross sections for low-energy electrons in liquid water: exchange and correlation effects.
Emfietzoglou, Dimitris; Kyriakou, Ioanna; Garcia-Molina, Rafael; Abril, Isabel; Nikjoo, Hooshang
2013-11-01
Low-energy electrons play a prominent role in radiation therapy and biology as they are the largest contributor to the absorbed dose. However, no tractable theory exists to describe the interaction of low-energy electrons with condensed media. This article presents a new approach to include exchange and correlation (XC) effects in inelastic electron scattering at low energies (below ∼10 keV) in the context of the dielectric theory. Specifically, an optical-data model of the dielectric response function of liquid water is developed that goes beyond the random phase approximation (RPA) by accounting for XC effects using the concept of the many-body local-field correction (LFC). It is shown that the experimental energy-loss-function of liquid water can be reproduced by including into the RPA dispersion relations XC effects (up to second order) calculated in the time-dependent local-density approximation with the addition of phonon-induced broadening in N. D. Mermin's relaxation-time approximation. Additional XC effects related to the incident and/or struck electrons are included by means of the vertex correction calculated by a modified Hubbard formula for the exchange-only LFC. Within the first Born approximation, the present XC corrections cause a significantly larger reduction (∼10-50%) to the inelastic cross section compared to the commonly used Mott and Ochkur approximations, while also yielding much better agreement with the recent experimental data for amorphous ice. The current work offers a manageable, yet rigorous, approach for including non-Born effects in the calculation of inelastic cross sections for low-energy electrons in liquid water, which due to its generality, can be easily extended to other condensed media.
NASA Astrophysics Data System (ADS)
Deur, Killian; Mazouin, Laurent; Fromager, Emmanuel
2017-01-01
Ensemble density functional theory (eDFT) is an exact time-independent alternative to time-dependent DFT (TD-DFT) for the calculation of excitation energies. Despite its formal simplicity and advantages in contrast to TD-DFT (multiple excitations, for example, can be easily taken into account in an ensemble), eDFT is not standard, which is essentially due to the lack of reliable approximate exchange-correlation (x c ) functionals for ensembles. Following Smith et al. [Phys. Rev. B 93, 245131 (2016), 10.1103/PhysRevB.93.245131], we propose in this work to construct an exact eDFT for the nontrivial asymmetric Hubbard dimer, thus providing more insight into the weight dependence of the ensemble x c energy in various correlation regimes. For that purpose, an exact analytical expression for the weight-dependent ensemble exchange energy has been derived. The complementary exact ensemble correlation energy has been computed by means of Legendre-Fenchel transforms. Interesting features like discontinuities in the ensemble x c potential in the strongly correlated limit have been rationalized by means of a generalized adiabatic connection formalism. Finally, functional-driven errors induced by ground-state density-functional approximations have been studied. In the strictly symmetric case or in the weakly correlated regime, combining ensemble exact exchange with ground-state correlation functionals gives better ensemble energies than when calculated with the ground-state exchange-correlation functional. However, when approaching the asymmetric equiensemble in the strongly correlated regime, the former approximation leads to highly curved ensemble energies with negative slope which is unphysical. Using both ground-state exchange and correlation functionals gives much better results in that case. In fact, exact ensemble energies are almost recovered in some density domains. The analysis of density-driven errors is left for future work.
Noguchi, Yoshifumi; Ohno, Kaoru
2010-04-15
The optical absorption spectra of sodium clusters (Na{sub 2n}, n{<=} 4) are calculated by using an all-electron first-principles GW+Bethe-Salpeter method with the mixed-basis approach within the Tamm-Dancoff approximation. In these small systems, the excitonic effect strongly affects the optical properties due to the confinement of exciton in the small system size. The present state-of-the-art method treats the electron-hole two-particle Green's function by incorporating the ladder diagrams up to the infinite order and therefore takes into account the excitonic effect in a good approximation. We check the accuracy of the present method by comparing the resulting spectra with experiments. In addition, the effect of delocalization in particular in the lowest unoccupied molecular orbital in the GW quasiparticle wave function is also discussed by rediagonalizing the Dyson equation.
Calculation of smooth potential energy surfaces using local electron correlation methods
NASA Astrophysics Data System (ADS)
Mata, Ricardo A.; Werner, Hans-Joachim
2006-11-01
The geometry dependence of excitation domains in local correlation methods can lead to noncontinuous potential energy surfaces. We propose a simple domain merging procedure which eliminates this problem in many situations. The method is applied to heterolytic bond dissociations of ketene and propadienone, to SN2 reactions of Cl- with alkylchlorides, and in a quantum mechanical/molecular mechanical study of the chorismate mutase enzyme. It is demonstrated that smooth potentials are obtained in all cases. Furthermore, basis set superposition error effects are reduced in local calculations, and it is found that this leads to better basis set convergence when computing barrier heights or weak interactions. When the electronic structure strongly changes between reactants or products and the transition state, the domain merging procedure leads to a balanced description of all structures and accurate barrier heights.
Calculation of smooth potential energy surfaces using local electron correlation methods
Mata, Ricardo A.; Werner, Hans-Joachim
2006-11-14
The geometry dependence of excitation domains in local correlation methods can lead to noncontinuous potential energy surfaces. We propose a simple domain merging procedure which eliminates this problem in many situations. The method is applied to heterolytic bond dissociations of ketene and propadienone, to SN2 reactions of Cl{sup -} with alkylchlorides, and in a quantum mechanical/molecular mechanical study of the chorismate mutase enzyme. It is demonstrated that smooth potentials are obtained in all cases. Furthermore, basis set superposition error effects are reduced in local calculations, and it is found that this leads to better basis set convergence when computing barrier heights or weak interactions. When the electronic structure strongly changes between reactants or products and the transition state, the domain merging procedure leads to a balanced description of all structures and accurate barrier heights.
NASA Astrophysics Data System (ADS)
Rojas, Laura; Ruette, Fernando; Peraza, Alexander; Castellano, Olga; Soscún, Humberto
2015-04-01
Interaction energies (Eint) were evaluated for n-alkanes dimers (C1-C10) using DFT-D, different functionals, and several basis sets. In addition, calculations were also carried out with DFTB-LD and MM3 and OPLS-AA force fields. Results show linear correlations of Eint with respect to those obtained from literature at high levels of theory (MP2 and CCSD(T)). Relationships between Eint and experimental heats of vaporization (ΔHv) and critical temperatures (Tc) were obtained with MP2, DFT-D, MM and DFTB-LD. This leads to good extrapolations for hairpin-hexadecane using MM3 and DFTB-LD for ΔHv and Tc, respectively. Dispersion in DFT is discussed.
Correlated electric field and low-energy electron measurements in the low-altitude polar cusp
NASA Technical Reports Server (NTRS)
Kintner, P. M.; Ackerson, K. L.; Gurnett, D. A.; Frank, L. A.
1978-01-01
Correlated electric field and low-energy electron measurements are presented for two passes of Hawkeye 1 through the south polar cusp at 2000-km altitude during local morning. In one case the electric field reversal coincides with the boundary of detectable 5.2keV electron intensities and the equatorward boundary of the cusp. In the other case the electric field reversal and the 5.2 keV electron trapping boundary coincide, but the equatorward edge of the cusp as determined from the presence of 180 eV electron intensities is 5 degrees invariant latitude equatorward of the electric field reversal. It is concluded that in the second case, electron intensities associated with the polar cusp populate closed dayside field lines, and hence the corresponding equatorward edge of these electron intensities is not always an indicator of the boundary between closed dayside field lines and polar cap field lines.
Correlation measurements in nuclear {beta}-decay using traps and polarized low energy beams
Naviliat-Cuncic, Oscar
2013-05-06
Precision measurements in nuclear {beta}-decay provide sensitive means to test discrete symmetries in the weak interaction and to determine some of the fundamental constants in semi-leptonic decays, like the coupling of the lightest quarks to charged weak bosons. The main motivation of such measurements is to find deviations from Standard Model predictions as possible indications of new physics. In this contribution I will focus on two topics related to precision measurements in nuclear {beta}-decay: i) the determination of the V{sub ud} element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix from nuclear mirror transitions and ii) the search for exotic scalar or tensor contributions from {beta}{nu} angular correlations. The purpose is to underline the role being played by experimental techniques based on the confinement of radioactive species with atom and ion traps as well as the plans to use low energy polarized beams.
Abrecht, David G; Schwantes, Jon M
2015-03-03
This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the initial source of the radionuclides to the environment to be from active reactors rather than the spent fuel pool. Linear correlations of the form In χ = −α ((ΔGrxn°(TC))/(RTC)) + β were obtained between the deposited concentrations, and the reduction potentials of the fission product oxide species using multiple reduction schemes to calculate ΔG°rxn (TC). These models allowed an estimate of the upper bound for the reactor temperatures of TC between 2015 and 2060 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products 90Sr, 121mSn, 147Pm, 144Ce, 152Eu, 154Eu, 155Eu, and 151Sm through atmospheric venting during the first month following the accident were obtained, indicating that large quantities of 90Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.
Optimal composition of atomic orbital basis sets for recovering static correlation energies.
Wallace, Andrew J; Crittenden, Deborah L
2014-03-20
Static correlation energies (Estat) are calculated in a range of basis sets for a chemically diverse collection of atoms and molecules. The reliability of a basis set in capturing Estat is assessed according to the following: mean and maximum absolute deviations from near-exact Estat estimates, monotonic convergence to the complete basis set limit, and ability to capture Estat accurately independent of changes in geometry, molecular size, and electronic configuration. Within the polarization and correlation-consistent basis set series, triple-ζ basis sets are the smallest that can reliably capture Estat. The cc-pVTZ basis set performs particularly well, recovering Estat to chemical accuracy for all atoms and molecules in our data set. A series of customized basis sets are constructed by stripping polarization functions from, and swapping polarization functions among, existing basis sets. Basis sets without polarization functions are incapable of accurately recovering Estat. Basis sets with a near-complete set of s, p, and d functions can approach chemical accuracy in maximum absolute error. However, this may be achieved at lower computational cost by using a well balanced triple-ζ basis set including f functions, along with a smaller number of s, p, and d functions. Recommended basis sets for calculating Estat with increasing accuracy at increasing computational cost are 6-311G(2d,2p), cc-pVTZ, and cc-pVQZ stripped of g functions.
Borexino's search for low-energy neutrino and antineutrino signals correlated with gamma-ray bursts
NASA Astrophysics Data System (ADS)
Agostini, M.; Altenmüller, K.; Appel, S.; Atroshchenko, V.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Carlini, M.; Cavalcante, P.; Chepurnov, A.; Choi, K.; D'Angelo, D.; Davini, S.; de Kerret, H.; Derbin, A.; Di Noto, L.; Drachnev, I.; Etenko, A.; Fomenko, K.; Franco, D.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Gromov, M.; Hagner, C.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jany, A.; Jedrzejczak, K.; Jeschke, D.; Kobychev, V.; Korablev, D.; Korga, G.; Kryn, D.; Laubenstein, M.; Lehnert, B.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Machulin, I.; Manecki, S.; Maneschg, W.; Manuzio, G.; Marcocci, S.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Montuschi, M.; Mosteiro, P.; Muratova, V.; Neumair, B.; Oberauer, L.; Obolensky, M.; Ortica, F.; Pallavicini, M.; Papp, L.; Pocar, A.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Semenov, D.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Unzhakov, E.; Vishneva, A.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Winter, J.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.
2017-01-01
A search for neutrino and antineutrino events correlated with 2350 gamma-ray bursts (GRBs) is performed with Borexino data collected between December 2007 and November 2015. No statistically significant excess over background is observed. We look for electron antineutrinos (νbare) that inverse beta decay on protons with energies from 1.8 MeV to 15 MeV and set the best limit on the neutrino fluence from GRBs below 8 MeV. The signals from neutrinos and antineutrinos from GRBs that scatter on electrons are also searched for, a detection channel made possible by the particularly radio-pure scintillator of Borexino. We obtain currently the best limits on the neutrino fluence of all flavors and species below 7 MeV. Finally, time correlations between GRBs and bursts of events are investigated. Our analysis combines two semi-independent data acquisition systems for the first time: the primary Borexino readout optimized for solar neutrino physics up to a few MeV, and a fast waveform digitizer system tuned for events above 1 MeV.
Abrecht, David G.; Schwantes, Jon M.
2015-03-03
This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes, et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the source of the radionuclides to be from active reactors rather than the spent fuel pool. Linear correlations of the form ln χ = -α (ΔG_{rxn}°(T_{C}))/(RT_{C})+β were obtained between the deposited concentration and the reduction potential of the fission product oxide species using multiple reduction schemes to calculate ΔG°_{rxn}(T_{C}). These models allowed an estimate of the upper bound for the reactor temperatures of T_{C} between 2130 K and 2220 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products ^{90}Sr, ^{121m}Sn, ^{147}Pm, ^{144}Ce, ^{152}Eu, ^{154}Eu, ^{155}Eu, ^{151}Sm through atmospheric venting and releases during the first month following the accident were performed, and indicate large quantities of ^{90}Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.
Unified Green's function retrieval by cross-correlation; connection with energy principles.
Snieder, Roel; Wapenaar, Kees; Wegler, Ulrich
2007-03-01
It has been shown theoretically and observationally that the Green's function for acoustic and elastic waves can be retrieved by cross-correlating fluctuations recorded at two locations. We extend the concept of the extraction of the Green's function to a wide class of scalar linear systems. For systems that are not invariant under time reversal, the fluctuations must be excited by volume sources in order to satisfy the energy balance (equipartitioning) that is needed to extract the Green's function. The general theory for retrieving the Green's function is illustrated with examples that include the diffusion equation, Schrödinger's equation, a vibrating string, the acoustic wave equation, a vibrating beam, and the advection equation. Examples are also shown of situations where the Green's function cannot be extracted from ambient fluctuations. The general theory opens up new applications for the extraction of the Green's function from field correlations that include flow in porous media, quantum mechanics, and the extraction of the response of mechanical structures such as bridges.
Sirianni, Dominic A; Burns, Lori A; Sherrill, C David
2017-01-10
The reliability of explicitly correlated methods for providing benchmark-quality noncovalent interaction energies was tested at various levels of theory and compared to estimates of the complete basis set (CBS) limit. For all systems of the A24 test set, computations were performed using both aug-cc-pVXZ (aXZ; X = D, T, Q, 5) basis sets and specialized cc-pVXZ-F12 (XZ-F12; X = D, T, Q, 5) basis sets paired with explicitly correlated coupled cluster singles and doubles [CCSD-F12n (n = a, b, c)] with triple excitations treated by the canonical perturbative method and scaled to compensate for their lack of explicit correlation [(T**)]. Results show that aXZ basis sets produce smaller errors versus the CBS limit than XZ-F12 basis sets. The F12b ansatz results in the lowest average errors for aTZ and larger basis sets, while F12a is best for double-ζ basis sets. When using aXZ basis sets (X ≥ 3), convergence is achieved from above for F12b and F12c ansatzë and from below for F12a. The CCSD(T**)-F12b/aXZ approach converges quicker with respect to basis than any other combination, although the performance of CCSD(T**)-F12c/aXZ is very similar. Both CCSD(T**)-F12b/aTZ and focal point schemes employing density-fitted, frozen natural orbital [DF-FNO] CCSD(T)/aTZ exhibit similar accuracy and computational cost, and both are much more computationally efficient than large-basis conventional CCSD(T) computations of similar accuracy.
NASA Astrophysics Data System (ADS)
Ning, Shuang; Bian, Xiufang; Ren, Zhenfeng
2010-09-01
Activation energy is obtained from temperature dependence of viscosities by means of a fitting to the Arrhenius equation for liquid alloys of Cu-Sb, Cu-Te, Cu-Sn and Cu-Ag systems. We found that the changing trend of activation energy curves with concentration is similar to that of liquidus in the phase diagrams. Moreover, a maximum value of activation energy is in the composition range of the intermetallic phases and a minimum value of activation energy is located at the eutectic point. The correlation between the activation energy and the phase diagrams has been further discussed.
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Abreu, P.; Aglietta, M.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; /Wisconsin U., Milwaukee /Lisbon, IST
2010-06-01
Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuzmin energy threshold, 6 x 10{sup 19} eV. The anisotropy was measured by the fraction of arrival directions that are less than 3.1{sup o} from the position of an active galactic nucleus within 75 Mpc (using the Veron-Cetty and Veron 12th catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (38{sub -6}{sup +7})%, compared with 21% expected for isotropic cosmic rays. This is down from the early estimate of (69{sub -13}{sup +11})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
NASA Astrophysics Data System (ADS)
Abreu, P.; Aglietta, M.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; Berat, C.; Bergmann, T.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Colombo, E.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; Deligny, O.; Della Selva, A.; Dembinski, H.; Denkiewicz, A.; Di Giulio, C.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fröhlich, U.; Fuchs, B.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Gascon, A.; Gelmini, G.; Gemmeke, H.; Gesterling, K.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Góra, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hague, J. D.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Hrabovský, M.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kadija, K.; Kaducak, M.; Kampert, K. H.; Karhan, P.; Karova, T.; Kasper, P.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Mičanović, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafá, M.; Mueller, S.; Muller, M. A.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Parrisius, J.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Peķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Phan, N.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rivière, C.; Rizi, V.; Robledo, C.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schroeder, F.; Schulte, S.; Schüssler, F.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Stapleton, J.; Stasielak, J.; Stephan, M.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Tamashiro, A.; Tapia, A.; Tarutina, T.; Taşcău, O.; Tcaciuc, R.; Tcherniakhovski, D.; Tegolo, D.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tiwari, D. K.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Warner, D.; Watson, A. A.; Weidenhaupt, K.; Weindl, A.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Winders, L.; Winnick, M. G.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Ziolkowski, M.; Pierre Auger Collaboration
Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, 6 × 10 19 eV. The anisotropy was measured by the fraction of arrival directions that are less than 3.1° from the position of an active galactic nucleus within 75 Mpc (using the Véron-Cetty and Véron 12th catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is 38-6+7%, compared with 21% expected for isotropic cosmic rays. This is down from the early estimate of 69-13+11%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.
Climatic correlates of tree mortality in water- and energy-limited forests
Das, Adrian J.; Stephenson, Nathan L.; Flint, Alan; Das, Tapash; van Mantgem, Phillip J.
2013-01-01
Recent increases in tree mortality rates across the western USA are correlated with increasing temperatures, but mechanisms remain unresolved. Specifically, increasing mortality could predominantly be a consequence of temperature-induced increases in either (1) drought stress, or (2) the effectiveness of tree-killing insects and pathogens. Using long-term data from California’s Sierra Nevada mountain range, we found that in water-limited (low-elevation) forests mortality was unambiguously best modeled by climatic water deficit, consistent with the first mechanism. In energy-limited (high-elevation) forests deficit models were only equivocally better than temperature models, suggesting that the second mechanism is increasingly important in these forests. We could not distinguish between models predicting mortality using absolute versus relative changes in water deficit, and these two model types led to different forecasts of mortality vulnerability under future climate scenarios. Our results provide evidence for differing climatic controls of tree mortality in water- and energy-limited forests, while highlighting the need for an improved understanding of tree mortality processes.
Climatic correlates of tree mortality in water- and energy-limited forests.
Das, Adrian J; Stephenson, Nathan L; Flint, Alan; Das, Tapash; van Mantgem, Phillip J
2013-01-01
Recent increases in tree mortality rates across the western USA are correlated with increasing temperatures, but mechanisms remain unresolved. Specifically, increasing mortality could predominantly be a consequence of temperature-induced increases in either (1) drought stress, or (2) the effectiveness of tree-killing insects and pathogens. Using long-term data from California's Sierra Nevada mountain range, we found that in water-limited (low-elevation) forests mortality was unambiguously best modeled by climatic water deficit, consistent with the first mechanism. In energy-limited (high-elevation) forests deficit models were only equivocally better than temperature models, suggesting that the second mechanism is increasingly important in these forests. We could not distinguish between models predicting mortality using absolute versus relative changes in water deficit, and these two model types led to different forecasts of mortality vulnerability under future climate scenarios. Our results provide evidence for differing climatic controls of tree mortality in water- and energy-limited forests, while highlighting the need for an improved understanding of tree mortality processes.
Climatic Correlates of Tree Mortality in Water- and Energy-Limited Forests
Das, Adrian J.; Stephenson, Nathan L.; Flint, Alan; Das, Tapash; van Mantgem, Phillip J.
2013-01-01
Recent increases in tree mortality rates across the western USA are correlated with increasing temperatures, but mechanisms remain unresolved. Specifically, increasing mortality could predominantly be a consequence of temperature-induced increases in either (1) drought stress, or (2) the effectiveness of tree-killing insects and pathogens. Using long-term data from California’s Sierra Nevada mountain range, we found that in water-limited (low-elevation) forests mortality was unambiguously best modeled by climatic water deficit, consistent with the first mechanism. In energy-limited (high-elevation) forests deficit models were only equivocally better than temperature models, suggesting that the second mechanism is increasingly important in these forests. We could not distinguish between models predicting mortality using absolute versus relative changes in water deficit, and these two model types led to different forecasts of mortality vulnerability under future climate scenarios. Our results provide evidence for differing climatic controls of tree mortality in water- and energy-limited forests, while highlighting the need for an improved understanding of tree mortality processes. PMID:23936118
Mourik, Van Tonja; Wilson, Angela K.; Dunning, Thomas H.
1999-02-20
The potential energy curves of the rare gas dimers He2, Ne2, and Ar2 have been computed using correlation consistent basis sets ranging from singly augmented aug-cc-pVDZ sets through triply augmented t-aug-cc-pV6Z sets, with the augmented sextuple basis sets being reported herein. Several methods for including electron correlation were investigated, namely Moller Plesset perturbation theory (MP2, MP3 and MP4) and coupled cluster theory [CCSD and CCSD(T)].
Ishida, Toyokazu; Fedorov, Dmitri G; Kitaura, Kazuo
2006-01-26
To elucidate the catalytic power of enzymes, we analyzed the reaction profile of Claisen rearrangement of Bacillus subtilis chorismate mutase (BsCM) by all electron quantum chemical calculations using the fragment molecular orbital (FMO) method. To the best of our knowledge, this is the first report of ab initio-based quantum chemical calculations of the entire enzyme system, where we provide a detailed analysis of the catalytic factors that accomplish transition-state stabilization (TSS). FMO calculations deliver an ab initio-level estimate of the intermolecular interaction between the substrate and the amino acid residues of the enzyme. To clarify the catalytic role of Arg90, we calculated the reaction profile of the wild-type BsCM as well as Lys90 and Cit90 mutant BsCMs. Structural refinement and the reaction path determination were performed at the ab initio QM/MM level, and FMO calculations were applied to the QM/MM refined structures. Comparison between three types of reactions established two collective catalytic factors in the BsCM reaction: (1) the hydrogen bonds connecting the Glu78-Arg90-substrate cooperatively control the stability of TS relative to the ES complex and (2) the positive charge on Arg90 polarizes the substrate in the TS region to gain more electrostatic stabilization.
NASA Astrophysics Data System (ADS)
Li, Jun; Williamson, Andrew
2005-03-01
Recent experimentsootnotetextY. Wu, et.al., Nature 430, 61 (2004); and references therein invoke Si nanowires as promising materials for nanoscale electronic and optical devices. We carried out electronic structure calculations of silicon chains and nanowires, by using both the full-potential linearized augmented plane wave (FLAPW) methodootnotetextE.Wimmer, H.Krakauer, M.Weinert, AJ Freeman, PRB 24, 864 (1981) and the pseudopotential plane wave method. We studied two sets of H-terminated one nanometer silicon wires, one oriented along (001) and the other along(111); both show direct band gaps, with the (111) oriented wires showing a smaller gap (˜2.1 eV) than (001) (˜2.5 eV). This trend differs from that reported in the literature ootnotetextF. Buda, et.al., PRL 69, 1272 (1992); A. M. Saitta, et.al., PRB 53, 1446 (1996), but it is the same in both our all-electron and well converged pseudopotential calculations. We also found that structural relaxations induce different effects on the band structure of differently oriented wires; the band gap change is nearly 0.2 eV between the ideal and relaxed models for (001) while it is negligible for (111) wires.
NASA Astrophysics Data System (ADS)
Yang, Jia-Yue; Yue, Sheng-Ying; Hu, Ming
2016-12-01
Considerable discussions have occurred about the critical role played by free electrons in the transport of heat in pure metals. In principle, any environment that can influence the dynamical behaviors of electrons would have impact on electronic thermal conductivity (κel) of metals. Over the past decades, significant progress and comprehensive understanding have been gained from theoretical, as well as experimental, investigations by taking into account the effects of various conditions, typically temperature, impurities, strain, dimensionality, interface, etc. However, the effect of external magnetic field has received less attention. In this paper, the magnetic-field dependence of electron-phonon scattering, the electron's lifetime, and κel of representative metals (Al, Ni, and Nb) are investigated within the framework of all-electron spin-density functional theory. For Al and Ni, the induced magnetization vector field and difference in electron density under external magnetic-field aggregate toward the center of unit cell, leading to the enhanced electron-phonon scattering, the damped electron's lifetime, and thus the reduced κel. On the contrary, for Nb with strong intrinsic electron-phonon interaction, the electron's lifetime and κel slightly increase as external magnetic field is enhanced. This is mainly attributed to the separately distributed magnetization vector field and difference in electron density along the corner of unit cell. This paper sheds light on the origin of influence of external magnetic field on κel for pure metals and offers a new route for robust manipulation of electronic thermal transport via applying external magnetic field.
NASA Astrophysics Data System (ADS)
Egan, C. K.; Scuffham, J. W.; Veale, M. C.; Wilson, M. D.; Seller, P.; Cernik, R. J.
2017-01-01
We describe the implementation of a reliable, robust and flexible gain correction and energy calibration algorithm for pixelated spectroscopic x-ray detectors. This algorithm uses a data processing method known as correlation optimised warping which aligns shifted datasets by means of a segmental linear stretching and compression of the spectral data in order to best correlate with a reference spectrum. We found the algorithm to be very robust against low-count spectroscopy, and was reliable in a range of different spectroscopic applications. Analysis of the integrated spectrum over all pixels for a Cerium K-alpha x-ray emission (at 34.72 keV) yielded a peak width of 2.45 keV before alignment and 1.11 keV after alignment. This compares favourably with the best in class pixel peak width of 0.76 keV and the mean peak width for all pixels of 1.00 keV. We also found the algorithm to be more user friendly than other peak-search algorithms because there is less external input. A key advantage of this algorithm is that it requires no prior knowledge of the input spectral characteristics, shape or quality of the data. This therefore lends itself to being useful for in-line processing and potentially removes the need for a separate calibration standard (e.g. a radioactive source). This algorithm can be used for any system that simultaneously collects large numbers of spectral data—including multi-element detectors.
Ion Beam Analysis Of Silicon-Based Surfaces And Correlation With Surface Energy Measurements
Xing Qian; Herbots, N.; Hart, M.; Bradley, J. D.; Wilkens, B. J.; Sell, D. A.; Culbertson, R. J.; Whaley, S. D.; Sell, Clive H.; Kwong, Henry Mark Jr.
2011-06-01
The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain hydrophobic or hydrophilic behavior of silicone, silicates, and silicon surfaces. Surface defects such as dangling bonds, surface free energy including Lewis acid-base and Lifshitz-van der Waals components are discussed. Water nucleation and condensation is further explained by surface topography. Tapping mode atomic force microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces. The correlation of the above two characteristics describes the behavior of water condensation at Si-based surfaces. Surface root mean square roughness increasing from several A ring to several nm is found to provide nucleation sites that expedite water condensation visibly for silica and silicone. Hydrophilic surfaces have a condensation pattern that forms puddles of water while hydrophobic surfaces form water beads. Polymer adsorption on these surfaces alters the water affinity as well as the surface topography, and therefore controls condensation on Si-based surfaces including silicone intraocular lens (IOL). The polymer film is characterized by Rutherford backscattering spectrometry (RBS) in conjunction with 4.265 MeV {sup 12}C({alpha}, {alpha}){sup 12}C, 3.045 MeV {sup 16}O({alpha},{alpha}){sup 16}O nuclear resonance scattering (NRS), and 2.8 MeV elastic recoil detection (ERD) of hydrogen for high resolution composition and areal density measurements. The areal density of hydroxypropyl methylcellulose (HPMC) film ranges from 10{sup 18} atom/cm{sup 2} to 10{sup 19} atom/cm{sup 2} gives the silica or silicone surface a roughness of several A ring and a wavelength of 0.16{+-}0.02 {mu}m, and prevents fogging by forming a complete wetting layer during water condensation.
Stannard, D.I.; Rosenberry, D.O.
1991-01-01
Concurrent short-term measurements of evaporation from a shallow lake, using eddy correlation and energy budget methods, indicate that sensible and latent heat flux between lake and atmosphere, and energy storage in the lake, may vary considerably across the lake. Measuring net radiation with a net radiometer on the lake appeared to be more accurate than measuring incoming radiation nearby and modeling outgoing radiation. Short-term agreement between the two evaporation measurements was obtained by using an energy storage term that was weighted to account for the area-of-influence of the eddy correlation sensors. Relatively short bursts of evaporation were indicated by the eddy correlation sensors shortly after midnight on two of three occasions. ?? 1991.
Kaweeteerawat, Chitrada; Ivask, Angela; Liu, Rong; Zhang, Haiyuan; Chang, Chong Hyun; Low-Kam, Cecile; Fischer, Heidi; Ji, Zhaoxia; Pokhrel, Suman; Cohen, Yoram; Telesca, Donatello; Zink, Jeffrey; Mädler, Lutz; Holden, Patricia A; Nel, Andre; Godwin, Hilary
2015-01-20
Metal oxide nanoparticles (MOx NPs) are used for a host of applications, such as electronics, cosmetics, construction, and medicine, and as a result, the safety of these materials to humans and the environment is of considerable interest. A prior study of 24 MOx NPs in mammalian cells revealed that some of these materials show hazard potential. Here, we report the growth inhibitory effects of the same series of MOx NPs in the bacterium Escherichia coli and show that toxicity trends observed in E. coli parallel those seen previously in mammalian cells. Of the 24 materials studied, only ZnO, CuO, CoO, Mn2O3, Co3O4, Ni2O3, and Cr2O3 were found to exert significant growth inhibitory effects; these effects were found to relate to membrane damage and oxidative stress responses in minimal trophic media. A correlation of the toxicological data with physicochemical parameters of MOx NPs revealed that the probability of a MOx NP being toxic increases as the hydration enthalpy becomes less negative and as the conduction band energy approaches those of biological molecules. These observations are consistent with prior results observed in mammalian cells, revealing that mechanisms of toxicity of MOx NPs are consistent across two very different taxa. These results suggest that studying nanotoxicity in E. coli may help to predict toxicity patterns in higher organisms.
NASA Astrophysics Data System (ADS)
Krause, Katharina; Klopper, Wim
2013-11-01
Within the framework of density-functional theory, the correlation energy is computed in the random-phase approximation (RPA) using spinors obtained from a two-component relativistic Kohn-Sham calculation accounting for spin-orbit interactions. Ring-coupled-cluster equations are solved to obtain the two-component RPA correlation energy. Results are presented for the hydrides of the halogens Br, I, and At as well as of the coinage metals Cu, Ag, and Au, based on two-component relativistic exact-decoupling Kohn-Sham calculations.
Krause, Katharina; Klopper, Wim
2013-11-21
Within the framework of density-functional theory, the correlation energy is computed in the random-phase approximation (RPA) using spinors obtained from a two-component relativistic Kohn–Sham calculation accounting for spin–orbit interactions. Ring-coupled-cluster equations are solved to obtain the two-component RPA correlation energy. Results are presented for the hydrides of the halogens Br, I, and At as well as of the coinage metals Cu, Ag, and Au, based on two-component relativistic exact-decoupling Kohn–Sham calculations.
NASA Astrophysics Data System (ADS)
Konstantaras, Anthony; Katsifarakis, Emmanouil; Artzouxaltzis, Xristos; Makris, John; Vallianatos, Filippos; Varley, Martin
2010-05-01
This paper is a preliminary investigation of the possible correlation of temporal and energy release patterns of seismic activity involving the preparation processes of consecutive sizeable seismic events [1,2]. The background idea is that during periods of low-level seismic activity, stress processes in the crust accumulate energy at the seismogenic area whilst larger seismic events act as a decongesting mechanism releasing considerable energy [3,4]. A dynamic algorithm is being developed aiming to identify and cluster pre- and post- seismic events to the main earthquake following on research carried out by Zubkov [5] and Dobrovolsky [6,7]. This clustering technique along with energy release equations dependent on Richter's scale [8,9] allow for an estimate to be drawn regarding the amount of the energy being released by the seismic sequence. The above approach is being implemented as a monitoring tool to investigate the behaviour of the underlying energy management system by introducing this information to various neural [10,11] and soft computing models [1,12,13,14]. The incorporation of intelligent systems aims towards the detection and simulation of the possible relationship between energy release patterns and time-intervals among consecutive sizeable earthquakes [1,15]. Anticipated successful training of the imported intelligent systems may result in a real-time, on-line processing methodology [1,16] capable to dynamically approximate the time-interval between the latest and the next forthcoming sizeable seismic event by monitoring the energy release process in a specific seismogenic area. Indexing terms: pattern recognition, long-term earthquake precursors, neural networks, soft computing, earthquake occurrence intervals References [1] Konstantaras A., Vallianatos F., Varley M.R. and Makris J. P.: ‘Soft computing modelling of seismicity in the southern Hellenic arc', IEEE Geoscience and Remote Sensing Letters, vol. 5 (3), pp. 323-327, 2008 [2] Eneva M. and
Yaddanapudi, S; Cai, B; Sun, B; Noel, C; Goddu, S; Mutic, S
2015-06-15
Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful for measuring several parameters of interest in linear accelerator (linac) quality assurance (QA). The purpose of this project was to evaluate the feasibility of using EPIDs for determining linac photon beam energies. Methods: Two non-clinical Varian TrueBeam linacs (Varian Medical Systems, Palo Alto, CA) with 6MV and 10MV photon beams were used to perform the measurements. The linacs were equipped with an amorphous silicon based EPIDs (aSi1000) that were used for the measurements. We compared the use of flatness versus percent depth dose (PDD) for predicting changes in linac photon beam energy. PDD was measured in 1D water tank (Sun Nuclear Corporation, Melbourne FL) and the profiles were measured using 2D ion-chamber array (IC-Profiler, Sun Nuclear) and the EPID. Energy changes were accomplished by varying the bending magnet current (BMC). The evaluated energies conformed with the AAPM TG142 tolerance of ±1% change in PDD. Results: BMC changes correlating with a ±1% change in PDD corresponded with a change in flatness of ∼1% to 2% from baseline values on the EPID. IC Profiler flatness values had the same correlation. We observed a similar trend for the 10MV beam energy changes. Our measurements indicated a strong correlation between changes in linac photon beam energy and changes in flatness. For all machines and energies, beam energy changes produced change in the uniformity (AAPM TG-142), varying from ∼1% to 2.5%. Conclusions: EPID image analysis of beam profiles can be used to determine linac photon beam energy changes. Flatness-based metrics or uniformity as defined by AAPM TG-142 were found to be more sensitive to linac photon beam energy changes than PDD. Research funding provided by Varian Medical Systems. Dr. Sasa Mutic receives compensation for providing patient safety training services from Varian Medical Systems, the sponsor of this study.
Mori, Toshifumi; Nakano, Katsuhiro; Kato, Shigeki
2010-08-14
The minimum energy conical intersection (MECI) optimization method with taking account of the dynamic electron correlation effect [T. Mori and S. Kato, Chem. Phys. Lett. 476, 97 (2009)] is extended to locate the MECI of nonequilibrium free energy surfaces in solution. A multistate electronic perturbation theory is introduced into the nonequilibrium free energy formula, which is defined as a function of solute and solvation coordinates. The analytical free energy gradient and interstate coupling vectors are derived, and are applied to locate MECIs in solution. The present method is applied to study the cis-trans photoisomerization reaction of a protonated Schiff base molecule (PSB3) in methanol (MeOH) solution. It is found that the effect of dynamic electron correlation largely lowers the energy of S{sub 1} state. We also show that the solvation effect strongly stabilizes the MECI obtained by twisting the terminal C=N bond to become accessible in MeOH solution, whereas the conical intersection is found to be unstable in gas phase. The present study indicates that both electron correlation and solvation effects are important in the photoisomerization reaction of PSB3. The effect of counterion is also examined, and seems to be rather small in solution. The structures of free energy surfaces around MECIs are also discussed.
NASA Astrophysics Data System (ADS)
Alam, N.; Agrawal, B. K.; Fortin, M.; Pais, H.; Providência, C.; Raduta, Ad. R.; Sulaksono, A.
2016-11-01
We examine the correlations of neutron star radii with the nuclear matter incompressibility, symmetry energy, and their slopes, which are the key parameters of the equation of state (EoS) of asymmetric nuclear matter. The neutron star radii and the EoS parameters are evaluated using a representative set of 24 Skyrme-type effective forces and 18 relativistic mean field models, and two microscopic calculations, all describing 2 M⊙ neutron stars. Unified EoSs for the inner-crust-core region have been built for all the phenomenological models, both relativistic and nonrelativistic. Our investigation shows the existence of a strong correlation of the neutron star radii with the linear combination of the slopes of the nuclear matter incompressibility and the symmetry energy coefficients at the saturation density. Such correlations are found to be almost independent of the neutron star mass in the range 0.6 -1.8 M⊙ . This correlation can be linked to the empirical relation existing between the star radius and the pressure at a nucleonic density between one and two times saturation density, and the dependence of the pressure on the nuclear matter incompressibility, its slope, and the symmetry energy slope. The slopes of the nuclear matter incompressibility and the symmetry energy coefficients as estimated from the finite nuclei data yield the radius of a 1.4 M⊙ neutron star in the range 11.09 -12.86 km.
NASA Astrophysics Data System (ADS)
Rohrmoser, M.; Gossiaux, P.-B.; Gousset, T.; Aichelin, J.
2017-01-01
Two-particle correlations obtained from parton showers that pass the hot and dense medium of the quark gluon plasma (QGP) can be used as an alternative observable, in addition to the combination of the nuclear modification factor RAA and the elliptic flow v 2, to study the mechanisms of in-medium heavy quark energy-loss. In particular, angular correlations represent a promising tool to distinguish between energy loss due to collisional and radiative interactions of jet and medium particles. To this end, parton cascades were created in Monte-Carlo simulations, where individual particles can undergo both parton splitting as well as an effective jet-medium interaction. A first model simulates the effects of induced radiations on parton cascades. Its consequences on angular correlations of partons within jets were studied in detail, with particular focus on angular broadening. The results can be compared to a second model that effectively describes elastic scatterings of jet and medium particles.
Searches for correlation between UHECR events and high-energy gammaray Fermi-LAT data
NASA Astrophysics Data System (ADS)
Mirabal, Nestor; Alvarez, Ezequiel; Cuoco, Alessandro; Zaharijas, Gabrijela; Fermi Collaboration
2017-01-01
The sources responsible for ultra high-energy cosmic rays (UHECRs) continue to be one of the most intriguing mysteries in astrophysics.We present a comprehensive search for correlations between high-energy (>= 1 GeV) gamma-ray events from the Fermi Large Area Telescope (LAT) and UHECRs (>= 60 EeV) detected by the Telescope Array and the Pierre Auger Observatory. We perform two separate searches. First, we conduct a standard cross-correlation analysis between the arrival directions of UHECRs and gamma-ray sources in the Second Catalog of Hard Fermi-LAT sources (2FHL). Second,we search for a possible correlation between UHECR directions and unresolved Fermi-LAT gamma-ray emission. We report our findings and their implications in the search for the origin of UHECRs.
Searches for correlation between UHECR events and high-energy gamma-ray Fermi-LAT data
NASA Astrophysics Data System (ADS)
Álvarez, Ezequiel; Cuoco, Alessandro; Mirabal, Nestor; Zaharijas, Gabrijela
2016-12-01
The astrophysical sources responsible for ultra high-energy cosmic rays (UHECRs) continue to be one of the most intriguing mysteries in astrophysics. We present a comprehensive search for correlations between high-energy (gtrsim 1 GeV) gamma-ray events from the Fermi Large Area Telescope (LAT) and UHECRs (gtrsim 60 EeV) detected by the Telescope Array and the Pierre Auger Observatory. We perform two separate searches. First, we conduct a standard cross-correlation analysis between the arrival directions of 148 UHECRs and 360 gamma-ray sources in the Second Catalog of Hard Fermi-LAT sources (2FHL). Second, we search for a possible correlation between UHECR directions and unresolved Fermi-LAT gamma-ray emission. For the latter, we use three different methods: a stacking technique with both a model-dependent and model-independent background estimate, and a cross-correlation function analysis. We also test for statistically significant excesses in gamma rays from signal regions centered on Cen A and the Telescope Array hotspot. No significant correlation is found in any of the analyses performed, except a weak (lesssim 2σ) hint of signal with the correlation function method on scales ~ 1°. Upper limits on the flux of possible power-law gamma-ray sources of UHECRs are derived.
The Effect of Core Correlation on the MP2 Hydration Free Energies of Li(+), Na(+), and K(.).
Li, Jicun; Wang, Feng
2016-09-01
Simple nonpolarizable molecular mechanics potentials were developed for Li(+), Na(+), and K(+) with the adaptive force matching (AFM) method using the second order Møller-Plesset perturbation theory (MP2) with the frozen core approximation as reference. The effects of different choices of core orbitals and basis sets in the MP2 calculations were investigated for Na(+) and Li(+). For Na(+), correlating the 2s2p electrons in MP2 changes its hydration free energy by 18 kJ/mol, which is surprisingly large, constituting to about 5% of the intrinsic hydration free energy of the ion. Whereas correlating the 2s2p electrons with the aug-cc-pCVTZ basis set leads to the best agreement with experiments, with the aug-cc-pVTZ basis set, a better hydration free energy will be obtained if the 2s2p are kept as frozen core orbitals. Even with nonpolarizable energy expressions, the AFM derived ion potentials predict the experimental hydration free energies of the various salts within 2% of experimental values, suggesting the robustness of the fitting procedure. However, the 2% agreement can only be achieved if the core correlation is modeled appropriately in the MP2 reference calculations.
Damasceno, M.V.; Pasqua, L.A.; Lima-Silva, A.E.; Bertuzzi, R.
2015-01-01
This study aimed to verify the association between the contribution of energy systems during an incremental exercise test (IET), pacing, and performance during a 10-km running time trial. Thirteen male recreational runners completed an incremental exercise test on a treadmill to determine the respiratory compensation point (RCP), maximal oxygen uptake (V˙O2max), peak treadmill speed (PTS), and energy systems contribution; and a 10-km running time trial (T10-km) to determine endurance performance. The fractions of the aerobic (WAER) and glycolytic (WGLYCOL) contributions were calculated for each stage based on the oxygen uptake and the oxygen energy equivalents derived by blood lactate accumulation, respectively. Total metabolic demand (WTOTAL) was the sum of these two energy systems. Endurance performance during the T10-km was moderately correlated with RCP, V˙O2maxand PTS (P<@0.05), and moderate-to-highly correlated with WAER, WGLYCOL, and WTOTAL (P<0.05). In addition, WAER, WGLYCOL, and WTOTAL were also significantly correlated with running speed in the middle (P<0.01) and final (P<0.01) sections of the T10-km. These findings suggest that the assessment of energy contribution during IET is potentially useful as an alternative variable in the evaluation of endurance runners, especially because of its relationship with specific parts of a long-distance race. PMID:26397970
NASA Astrophysics Data System (ADS)
Stoyanova, Alexandrina; Teale, Andrew M.; Toulouse, Julien; Helgaker, Trygve; Fromager, Emmanuel
2013-10-01
The alternative separation of exchange and correlation energies proposed by Toulouse et al. [Theor. Chem. Acc. 114, 305 (2005)] is explored in the context of multi-configuration range-separated density-functional theory. The new decomposition of the short-range exchange-correlation energy relies on the auxiliary long-range interacting wavefunction rather than the Kohn-Sham (KS) determinant. The advantage, relative to the traditional KS decomposition, is that the wavefunction part of the energy is now computed with the regular (fully interacting) Hamiltonian. One potential drawback is that, because of double counting, the wavefunction used to compute the energy cannot be obtained by minimizing the energy expression with respect to the wavefunction parameters. The problem is overcome by using short-range optimized effective potentials (OEPs). The resulting combination of OEP techniques with wavefunction theory has been investigated in this work, at the Hartree-Fock (HF) and multi-configuration self-consistent-field (MCSCF) levels. In the HF case, an analytical expression for the energy gradient has been derived and implemented. Calculations have been performed within the short-range local density approximation on H2, N2, Li2, and H2O. Significant improvements in binding energies are obtained with the new decomposition of the short-range energy. The importance of optimizing the short-range OEP at the MCSCF level when static correlation becomes significant has also been demonstrated for H2, using a finite-difference gradient. The implementation of the analytical gradient for MCSCF wavefunctions is currently in progress.
Bose-Einstein Correlation of High Energy Heavy Ion Collisions at CERN SPS
NASA Astrophysics Data System (ADS)
Lee, Yuk Yan
An experimental study was conducted at CERN, the European Organization for Nuclear Research, using the focussing spectrometer of the Experiment NA44 collaboration. Single particle spectra and two or three particle correlations for pi^+/-, K ^+/- and p^+/- were studied, for collisions of 450 Acdot GeV proton and 200 AcdotGeV S^{32} incident on Pb ^{208}, Be^9 and S^{32} targets. Results of pi^+pi^+ correlations from S + Pb collisions, pi ^-pi^- correlations from S + Pb collisions and pi^+pi^+ correlations from p + Pb collisions are presented in this thesis. Data have been fitted to a few different parameterizations. The two-pion correlation results are then compared with the kaon correlation results and other experiments' two-pion correlation results. The pion source radii are found to be larger than the kaon source radii and the pion correlation results are consistent with the results from other experiments. There is also very good agreement between our data and the Monte Carlo simulation results with RQMD.
Quest for band renormalization and self-energy in correlated f-electron systems
Durakiewicx, Tomasz
2009-01-01
Coexisting energy scales are observed in f-electron materials. Information about some of the low-energy scales is imprinted in the electron self-energy which can be measured by angle-resolved photoemission (ARPES). Such measurements in d-electron materials over the last decade were based on high energy- and momentum-resolution ARPES techniques used to extract the self-energy information from measured spectra. Simultaneously, many-body theoretical approaches have been developed to find a link between self-energy and many-body interactions. Here we show the transcription of such methods from d-electrons to f-electrons by presenting the first example of low energy scales in f-electron material USb{sub 2}, measured with synchrotron-based ARPES. Proposed approach will help in answering the fundamental questions about the complex nature of the heavy fermion state.
Moritz, B.; Schmitt, F.; Meevasana, W.; Johnston, S.; Motoyama, E.M.; Greven, M.; Lu, D.H.; Kim, C.; Scalettar, R.T.; Shen, Z.-X.; Devereaux, T.P.; /SLAC, SIMES
2010-02-15
Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). This paper demonstrates, using a combination of new ARPES measurements and quantum Monte Carlo simulations, that the HEA is not simply the byproduct of matrix element effects, but rather represents a cross-over from a quasi-particle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character, in both hole- and electron-doped cuprates. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying both hole and electron doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram.
Sheng, WC; Zhuang, ZB; Gao, MR; Zheng, J; Chen, JGG; Yan, YS
2015-01-08
The hydrogen oxidation/evolution reactions are two of the most fundamental reactions in distributed renewable electrochemical energy conversion and storage systems. The identification of the reaction descriptor is therefore of critical importance for the rational catalyst design and development. Here we report the correlation between hydrogen oxidation/evolution activity and experimentally measured hydrogen binding energy for polycrystalline platinum examined in several buffer solutions in a wide range of electrolyte pH from 0 to 13. The hydrogen oxidation/evolution activity obtained using the rotating disk electrode method is found to decrease with the pH, while the hydrogen binding energy, obtained from cyclic voltammograms, linearly increases with the pH. Correlating the hydrogen oxidation/evolution activity to the hydrogen binding energy renders a monotonic decreasing hydrogen oxidation/evolution activity with the hydrogen binding energy, strongly supporting the hypothesis that hydrogen binding energy is the sole reaction descriptor for the hydrogen oxidation/evolution activity on monometallic platinum.
Borgoo, Alex; Teale, Andrew M; Tozer, David J
2012-01-21
Correlated electron densities, experimental ionisation potentials, and experimental electron affinities are used to investigate the homogeneity of the exchange-correlation and non-interacting kinetic energy functionals of Kohn-Sham density functional theory under density scaling. Results are presented for atoms and small molecules, paying attention to the influence of the integer discontinuity and the choice of the electron affinity. For the exchange-correlation functional, effective homogeneities are highly system-dependent on either side of the integer discontinuity. By contrast, the average homogeneity-associated with the potential that averages over the discontinuity-is generally close to 4/3 when the discontinuity is computed using positive affinities for systems that do bind an excess electron and negative affinities for those that do not. The proximity to 4/3 becomes increasingly pronounced with increasing atomic number. Evaluating the discontinuity using a zero affinity in systems that do not bind an excess electron instead leads to effective homogeneities on the electron abundant side that are close to 4/3. For the non-interacting kinetic energy functional, the effective homogeneities are less system-dependent and the effect of the integer discontinuity is less pronounced. Average values are uniformly below 5/3. The study provides information that may aid the development of improved exchange-correlation and non-interacting kinetic energy functionals.
NASA Astrophysics Data System (ADS)
Freire, José A.
2005-09-01
We analyze a master equation model for the time-of-flight experiment in an organic material where the internal transport is due to thermally activated hops between localized molecular orbitals. An expression for the transit time of a photocreated carrier across a finite one-dimensional sample is obtained in terms of the orbital energies and the microscopic hopping rates. Two forms of hopping rates commonly used in the literature are considered, the Miller-Abrahams rate and the small-polaron or Marcus rate. The average of the transit time expression with respect to an arbitrary, correlated, Gaussian distribution of molecular orbital energies is obtained exactly for both forms of rates. We use this averaged expression to investigate how different forms of energetic correlations and of hopping rates leave their imprint on the field dependence of the mobility. We find that a Poole-Frenkel field dependence of the mobility at low fields is obtained both with a power-law and with an exponential correlation, moreover, the factor γ in μ˜exp(γE) is obtained and we find that its temperature dependence does not distinguish between the two forms of energetic correlation. The form of the hopping rate only manifests itself in the mobility at fields above a certain critical field whose expression for an arbitrary form of correlation is explicitly obtained.
NASA Technical Reports Server (NTRS)
Simon, F. F.; Miller, D. R.
1975-01-01
A generalized collector performance correlation was derived and shown by experimental verification to be of the proper form to account for the majority of the variable conditions encountered both in outdoor and in indoor collector tests. This correlation permits a determination of collector parameters which are essentially nonvarying under conditions which do vary randomly (outdoors) or conditions which vary in a controlled manner (indoors - simulator). It was shown that correlation of the experimental performance of collectors allows the following: (1) comparisons of different collector designs; (2) collector performance prediction under conditions that differ from the conditions of the test program; and (3) monitoring performance degradation effects.
Wood, D.R.
1987-10-01
We have studied the energy-energy correlation in e/sup +/e/sup -/ annihilation into hadrons at ..sqrt..s = 29 GeV using the Mark II detector at PEP. We find to O(..cap alpha../sub s//sup 2/) that ..cap alpha../sub s/ = 0.158 +- .003 +- .008 if hadronization is described by string fragmentation. Independent fragmentation schemes give ..cap alpha../sub s/ = .10 - .14, and give poor agreement with the data. A leading-log shower fragmentation model is found to describe the data well.
NASA Astrophysics Data System (ADS)
Constantin, Lucian A.; Terentjevs, Aleksandrs; Della Sala, Fabio; Fabiano, Eduardo
2015-01-01
We propose a simple gradient-dependent bound for the exchange-correlation energy (sLL), based on the recent nonlocal bound derived by Lewin and Lieb. We show that sLL is equivalent to the original Lieb-Oxford bound in rapidly varying density cases, but it is tighter for slowly varying density systems. To show the utility of the sLL bound we apply it to the construction of simple semilocal and nonlocal exchange and correlation functionals. In both cases improved results, with respect to the use of Lieb-Oxford bound, are obtained, showing the power of the sLL bound.
NASA Technical Reports Server (NTRS)
Weatherford, C. A.; Brown, F. B.; Temkin, A.
1987-01-01
In a recent calculation, an exact exchange method was developed for use in the partial-differential-equation approach to electron-molecule scattering and was applied to e-N2 scattering in the fixed-nuclei approximation with an adiabatic polarization potential at low energies (0-10 eV). Integrated elastic cross sections were calculated and found to be lower than experiment at energies both below and above the Pi(g) resonance. It was speculated at that time that improved experimental agreement could be obtained if a correlated target representation were used in place of the uncorrelated one. The present paper implements this suggestion and demonstrates the improved agreement. These calculations are also extended to higher energies (0-30 eV) so asd to include the Sigma(u) resonance. Some discrepancies among the experiments and between experiment and the various calculations at very low energy are noted.
NASA Astrophysics Data System (ADS)
Koehn, Christoph; Ebert, Ute
2015-04-01
Thunderstorms can emit high-energy particles, photons with energies of up to at least 40 MeV, leptons (electrons, positrons) and hadrons (neutrons and protons) with energies of tens of MeV. Some of these events have been correlated with negative lightning leaders propagating upwards in the cloud. For particular lightning events we show that photons, leptons and hadrons can reach ground altitude as well as satellite altitude, and we present the number as well as the spatial and energy distribution of photons, leptons and hadrons. We have reviewed the latest literature on cross sections for collisions of photons, leptons and hadrons with air molecules and have implemented them in our Monte Carlo code. We initialize a photon beam with the characteristic energy distribution of a TGF at thunderstorm altitude and we use the Monte Carlo model to trace these photons; we include the production of secondary electrons through photoionization, Compton scattering and pair production, the production of positrons through pair production as well as the production of neutrons and protons through photonuclear processes. Subsequently we calculate the motion and energy dissipation of these leptons and hadrons with the feedback of electrons and positrons producing new photons through Bremsstrahlung and through positron annihilation at shell electrons. Additionally we provide analytic estimates for the energy losses of photons, leptons and hadrons in the energy range between 0.03 eV and 100 MeV based on the relevant cross sections. We provide the spectral analysis of how many photons, leptons and hadrons will reach ground or satellite altitude and what their energies are, depending on the initial photon energy. This is of particular interest because of campaigns measuring fluxes of all these species at 0 and 500 km altitude without knowing the actual energies of initial electrons converting into photons within a thundercloud.
Zuo, Chun S; Lin, Pan; Vitaliano, Gordana; Wang, Kristina; Villafuerte, Rosemond; Lukas, Scott E
2015-01-01
Impaired brain energy metabolism is among the leading hypotheses in the pathogenesis of affective disorders and linking energy phosphates with states of tissue-function activity is a novel and non-invasive approach to differentiate healthy from unhealthy states. Resting state functional MRI (fMRI) has been established as an important tool for mapping cerebral regional activity and phosphorous chemical shift imaging ((31)P CSI) has been applied to measure levels of energy phosphates and phospholipids non-invasively in order to gain insight into the possible etiology of affective disorders. This is an initial attempt to identify the existence of a correlation between regional energy phosphates and connectivity at nodes of the posterior default mode network (DMN). Resting state fMRI in conjunction with (31)P 2D CSI was applied to 11 healthy controls and 11 depressed patients at 3 T. We found that differences between the two groups exist in correlation of lateral posterior parietal cortex functional connectivity and regional Pi/PCr. Results of this study indicate that resting-state-fMRI-guided (31)P CSI can provide new insight into depression via regional energy phosphates and functional connectivity.
NASA Astrophysics Data System (ADS)
Heltsley, Brian Keith
This work describes measurements of the total cross section and the energy-energy correlation cross section for hadronic events produced in electron-positron annihilation at a center-of-mass energy of 29 GeV. The performance of the MAC detector at PEP, featuring total absorption calorimetry and charged particle tracking over nearly the full solid angle, is examined and found to meet the original design requirements. The unique and optimal features of MAC are fully exploited to reduce the systematics involved in both measurements, resulting in significant quantitative tests of the theory of quantum chromodynamics. Special attention is focussed on radiative corrections to the total cross section, which constitute a critical component of the acceptance determination, and for the first time the effects of higher order than (alpha)('3) QED processes are included. The total cross section measurement yields R = 3.91 with a total error of (+OR-)2.7%, an accuracy not previously attained by other experiments. For the energy-energy correlation cross section, the consequences of combining pure quantum chromodynamics with contrasting fragmentation models are explored and compared with the data, and result in different values for the strong coupling constant, (alpha)(,s) (TURNEQ) 0.13 (+OR-) 0.02 for incoherent jet formation and 0.24 (+OR-) 0.04 in the string model.
A complete sample of bright Swift long gamma-ray bursts: testing the spectral-energy correlations
NASA Astrophysics Data System (ADS)
Nava, L.; Salvaterra, R.; Ghirlanda, G.; Ghisellini, G.; Campana, S.; Covino, S.; Cusumano, G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Melandri, A.; Sbarufatti, B.; Vergani, S. D.; Tagliaferri, G.
2012-04-01
We use a nearly complete sample of gamma-ray bursts (GRBs) detected by the Swift satellite to study the correlations between the spectral peak energy Epeak of the prompt emission, the isotropic energetics Eiso and the isotropic luminosity Liso. This GRB sample is characterized by a high level of completeness in redshift (90 per cent). This allows us to probe in an unbiased way the issue related to the physical origin of these correlations against selection effects. We find that one burst, GRB 061021, is an outlier to the Epeak-Eiso correlation. Despite this case, we find strong Epeak-Eiso and Epeak-Liso correlations for the bursts of the complete sample. Their slopes, normalizations and dispersions are consistent with those found with the whole sample of bursts with measured redshift and Epeak. This means that the biases present in the total sample commonly used to study these correlations do not affect their properties. Finally, we also find no evolution with redshift of the Epeak-Eiso and Epeak-Liso correlations.
Grassani, Davide; Simbula, Angelica; Pirotta, Stefano; Galli, Matteo; Menotti, Matteo; Harris, Nicholas C; Baehr-Jones, Tom; Hochberg, Michael; Galland, Christophe; Liscidini, Marco; Bajoni, Daniele
2016-04-01
Compact silicon integrated devices, such as micro-ring resonators, have recently been demonstrated as efficient sources of quantum correlated photon pairs. The mass production of integrated devices demands the implementation of fast and reliable techniques to monitor the device performances. In the case of time-energy correlations, this is particularly challenging, as it requires high spectral resolution that is not currently achievable in coincidence measurements. Here we reconstruct the joint spectral density of photons pairs generated by spontaneous four-wave mixing in a silicon ring resonator by studying the corresponding stimulated process, namely stimulated four wave mixing. We show that this approach, featuring high spectral resolution and short measurement times, allows one to discriminate between nearly-uncorrelated and highly-correlated photon pairs.
Grassani, Davide; Simbula, Angelica; Pirotta, Stefano; Galli, Matteo; Menotti, Matteo; Harris, Nicholas C.; Baehr-Jones, Tom; Hochberg, Michael; Galland, Christophe; Liscidini, Marco; Bajoni, Daniele
2016-01-01
Compact silicon integrated devices, such as micro-ring resonators, have recently been demonstrated as efficient sources of quantum correlated photon pairs. The mass production of integrated devices demands the implementation of fast and reliable techniques to monitor the device performances. In the case of time-energy correlations, this is particularly challenging, as it requires high spectral resolution that is not currently achievable in coincidence measurements. Here we reconstruct the joint spectral density of photons pairs generated by spontaneous four-wave mixing in a silicon ring resonator by studying the corresponding stimulated process, namely stimulated four wave mixing. We show that this approach, featuring high spectral resolution and short measurement times, allows one to discriminate between nearly-uncorrelated and highly-correlated photon pairs. PMID:27032688
Hikosaka, Y.; Soejima, K.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Andric, L.; Shigemasa, E.; Suzuki, I. H.; Nakano, M.; Ito, K.
2011-09-09
The direct observation of triple photoionization involving one inner shell and two valence electrons is reported. The energy distribution of the three photoelectrons emitted from Ne is obtained using a very efficient multielectron coincidence method using the magnetic bottle electron spectroscopic technique. A predominance of the direct path to triple photoionization for the formation of Ne{sup 3+} in the 1s2s{sup 2}2p{sup 4} configuration is observed. It is demonstrated that the energy distribution evolves with photon energy and indicates a significant difference with triple photoionization involving only valence electrons.
NASA Astrophysics Data System (ADS)
Jo, Yun-A.; Chang, Heon-Young
2016-12-01
An analysis of light curves and spectra of observed gamma-ray bursts in gamma-ray ranges is frequently demanded because the prompt emission contains immediate details regarding the central engine of gamma-ray bursts (GRBs). We have revisited the relationship between the collimation-corrected peak luminosity and the spectral lag, investigating the lag-luminosity relationships in great detail by focusing on spectral lags resulting from all possible combinations of channels. Firstly, we compiled the opening angle data and demonstrated that the distribution of opening angles of 205 long GRBs is represented by a double Gaussian function having maxima at 0.1 and 0.3 radians. We confirmed that the peak luminosity and the spectral lag are anti-correlated, both in the observer frame and in the source frame. We found that, in agreement with our previous conclusion, the correlation coefficient improves significantly in the source frame. It should be noted that spectral lags involving channel 2 (25-50 keV) yield high correlation coefficients, where Swift/Burst Alert Telescope (BAT) has four energy channels (channel 1: 15-25 keV, channel 2: 25-50 keV, channel 3: 50-100 keV, channel 4: 100-200 keV). We also found that peak luminosity is positively correlated with peak energy.
NASA Astrophysics Data System (ADS)
Salas, L. D.; Arce, J. C.
2017-02-01
For the S states of two-electron atoms, we introduce an exact and unique factorization of the internal eigenfunction in terms of a marginal amplitude, which depends functionally on the electron-nucleus distances r1 and r2, and a conditional amplitude, which depends functionally on the interelectronic distance r12 and parametrically on r1 and r2. Applying the variational principle, we derive pseudoeigenvalue equations for these two amplitudes, which cast the internal Schrödinger equation in a form akin to the Born-Oppenheimer separation of nuclear and electronic degrees of freedom in molecules. The marginal equation involves an effective radial Hamiltonian, which contains a nonadiabatic potential energy surface that takes into account all interparticle correlations in an averaged way, and whose unique eigenvalue is the internal energy. At each point (r1,r2) , such surface is, in turn, the unique eigenvalue in the conditional equation. Employing the ground state of He as prototype, we show that the nonadiabatic potential energy surface affords a molecularlike interpretation of the structure of the atom, and aids in the analysis of energetic and spatial aspects of the Coulomb correlation, in particular correlation-induced symmetry breaking and quantum phase transition.
NASA Astrophysics Data System (ADS)
Lu-Lu, Zhang; Yu-Zhi, Song; Shou-Bao, Gao; Yuan, Zhang; Qing-Tian, Meng
2016-05-01
A globally accurate single-sheeted double many-body expansion potential energy surface is reported for the first excited state of HS2 by fitting the accurate ab initio energies, which are calculated at the multireference configuration interaction level with the aug-cc-pVQZ basis set. By using the double many-body expansion-scaled external correlation method, such calculated ab initio energies are then slightly corrected by scaling their dynamical correlation. A grid of 2767 ab initio energies is used in the least-square fitting procedure with the total root-mean square deviation being 1.406 kcal·mol-1. The topographical features of the HS2(A2A‧) global potential energy surface are examined in detail. The attributes of the stationary points are presented and compared with the corresponding ab initio results as well as experimental and other theoretical data, showing good agreement. The resulting potential energy surface of HS2(A2A‧) can be used as a building block for constructing the global potential energy surfaces of larger S/H molecular systems and recommended for dynamic studies on the title molecular system. Project supported by the National Natural Science Foundation of China (Grant No. 11304185), the Taishan Scholar Project of Shandong Province, China, the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2014AM022), the Shandong Province Higher Educational Science and Technology Program, China (Grant No. J15LJ03), the China Postdoctoral Science Foundation (Grant No. 2014M561957), and the Post-doctoral Innovation Project of Shandong Province, China (Grant No. 201402013).
From Correlations to Causes: Transient Energy Injection into the Polar Thermosphere
NASA Astrophysics Data System (ADS)
Carlson, H. C.; Aruliah, A. L.; Skjaeveland, A.; Moen, J. I.
2014-12-01
We report data analysis, modeling, and theory leading to expectation of frequent and significant energy deposition transients in the dayside half of the polar cap. Magnetic reconnection signatures accompany them. Satellite-drag/density enhancements of 20-100% are commonly seen by CHAMP (Luhr et al, 2004). We calculate these to correspond to transient energy deposition rates at the feet of freshly reconnected open flux tubes, equaling 5-30 times solar EUV rates above 150 km altitude. That these density enhancements are observed all seasons, darkness or sunlight, IMF north or south (Kervalishvili and Luhr, 2013), is powerful evidence for ubiquitous and substantial dayside polar cap energy injection. Frictional drag heating is closest to the physical cause (Strangeway, 2011); we find response times ~ ¼ hour above 200 km. Altitude is key, Poynting flux measurements without coincident electron density profiles, can yield order of magnitude energy deposition rate errors (Richmond, 2010, Carlson et al, 2012).
Correlation of high energy muons with primary composition in extensive air shower
NASA Technical Reports Server (NTRS)
Chou, C.; Higashi, S.; Hiraoka, N.; Ozaki, S.; Sato, T.; Suwada, T.; Takahasi, T.; Umeda, H.
1985-01-01
An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed.
Accurate heat of formation for fully hydrided LaNi5 via the all-electron FLAPW approach
NASA Astrophysics Data System (ADS)
Zhao, Yu-Jun; Freeman, A. J.
2003-03-01
It is known that the theoretical/computational determination of the heat of formation for La_2Ni_10H_14, Δ H_f, is overestimated theoretically by 50% or more when a pseudopotential approach is employed.(Tatsumi et al), PRB 64, 184105(2001) Does this signify a failure of first-principles total energy calculations? Here, we employ the full-potential linearized augmented plane wave (FLAPW) method(Wimmer, Krakauer, Weinert, and Freeman, PRB 24), 864 (1981). within both the generalized gradient approximation (GGA) and the localized density approximation (LDA), with a highly precise treatment of the total energy of H2 molecule due to its critical role in the calculation of Δ H_f. The calculated Δ Hf (-31.1 KJ/mol-H_2) and geometry structure within GGA are in excellent agreement with experiment ( ˜ -32 KJ/mol-H_2). While LDA calculations underestimate the volume of LaNi5 by 10.4%, the final value of Δ Hf (-31.2 KJ/mol-H_2) is also in excellent agreement with experiment. These results show the success rather than failure of first-principles calculations. The electronic properties indicate that charge transfer from the interstitial region to the H atoms stabilizes the fully hydrided LaNi_5.
Heltsley, B.K.
1984-07-01
Direct photon production in hadronic events from e/sup +/e/sup -/ ..-->.. hadrons has been studied at ..sqrt..s=29 GeV using the MAC detector at PEP. Both the charge asymmetry in the final state jets and total yield have been used to determine values of quark charges, which are in good agreement with the predictions of the fractionally charged quark-parton model. Limits have been established for anomalous sources of direct photons. Measurements of the total cross section and energy-energy correlations for e/sup +/e/sup -/ ..-->.. hadrons at ..sqrt..s=29 GeV with the MAC detector are presented. Two complementary event selections for the precision R measurement are described, one accepting events over nearly the entire 4..pi.. solid angle (minimizing extrapolation to unseen phase space), and the other restricted to wide angles (reducing two-photon backgrounds). The two methods agree, yield R = 3.93 +- 0.10 (which includes the effects of higher order radiative corrections), and given ..cap alpha../sub s/ = 0.19 +- 0.07, independent of fragmentation. The asymmetry in the energy-energy correlation cross section yields different results for ..cap alpha../sub s/ in different models, 0.185 in the string model and from 0.105 to 0.140 for incoherent jet formation, depending on the gluon fragmentation and momentum conservation algorithms. The string fragmentation model provides a satisfactory description of the measured correlation cross section, whereas incoherent jet fragmentation does not. 35 references.
Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...
2016-03-18
In this paper, we present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au + Au collisions for energies ranging from √sNN = 7.7 to 200 GeV. The third harmonic vmore » $$2\\atop{3}$${ 2 } = , where Φ1 - Φ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη = η1-η2 . Nonzero v$$2\\atop{3}$${ 2 } is directly related to the previously observed large- Δη narrow- ΔΦ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v$$2\\atop{3}$${ 2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v$$2\\atop{3}$${ 2 } is consistent with zero. Finally, when scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v$$2\\atop{3}$${ 2 } for central collisions shows a minimum near √sNN = 20 GeV .« less
Tsai, Ming-Hui; Huang, Yueh-Min
2014-11-18
Wireless sensor networks (WSNs) have emerged as a promising solution for various applications due to their low cost and easy deployment. Typically, their limited power capability, i.e., battery powered, make WSNs encounter the challenge of extension of network lifetime. Many hierarchical protocols show better ability of energy efficiency in the literature. Besides, data reduction based on the correlation of sensed readings can efficiently reduce the amount of required transmissions. Therefore, we use a sub-clustering procedure based on spatial data correlation to further separate the hierarchical (clustered) architecture of a WSN. The proposed algorithm (2TC-cor) is composed of two procedures: the prediction model construction procedure and the sub-clustering procedure. The energy conservation benefits by the reduced transmissions, which are dependent on the prediction model. Also, the energy can be further conserved because of the representative mechanism of sub-clustering. As presented by simulation results, it shows that 2TC-cor can effectively conserve energy and monitor accurately the environment within an acceptable level.
Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC.
Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, E C; Attri, A; Averichev, G S; Bai, X; Bairathi, V; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandenburg, J D; Brandin, A V; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chatterjee, A; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A I; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Horvat, S; Huang, T; Huang, X; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jentsch, A; Jia, J; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikoła, D P; Kisel, I; Kisiel, A; Kochenda, L; Koetke, D D; Kosarzewski, L K; Kraishan, A F; Kravtsov, P; Krueger, K; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, X; Li, C; Li, X; Li, Y; Li, W; Lin, T; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, R; Ma, G L; Ma, Y G; Ma, L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Matis, H S; McDonald, D; McKinzie, S; Meehan, K; Mei, J C; Minaev, N G; Mioduszewski, S; Mishra, D; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Niida, T; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V A; Olvitt, D; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Pile, P; Pluta, J; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, A; Sharma, B; Sharma, M K; Shen, W Q; Shi, Z; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Singha, S; Skoby, M J; Smirnov, N; Smirnov, D; Solyst, W; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B; Sun, Z; Sun, X M; Sun, Y; Surrow, B; Svirida, D N; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A; Thäder, J; Thomas, J H; Timmins, A R; Tlusty, D; Todoroki, T; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbæk, F; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, G; Wang, J S; Wang, H; Wang, Y; Wang, Y; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xiao, Z G; Xie, W; Xie, G; Xin, K; Xu, Y F; Xu, Q H; Xu, N; Xu, H; Xu, Z; Xu, J; Yang, S; Yang, Y; Yang, Y; Yang, C; Yang, Y; Yang, Q; Ye, Z; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, Y; Zhang, J; Zhang, J; Zhang, S; Zhang, S; Zhang, Z; Zhang, J B; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M
2016-03-18
We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from sqrt[s_{NN}]=7.7 to 200 GeV. The third harmonic v_{3}^{2}{2}=⟨cos3(ϕ_{1}-ϕ_{2})⟩, where ϕ_{1}-ϕ_{2} is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη=η_{1}-η_{2}. Nonzero v_{3}^{2}{2} is directly related to the previously observed large-Δη narrow-Δϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v_{3}^{2}{2} persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v_{3}^{2}{2} is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v_{3}^{2}{2} for central collisions shows a minimum near sqrt[s_{NN}]=20 GeV.
Martinez-Casado, Ruth; Mallia, Giuseppe; Harrison, Nicholas M
2011-04-21
A practical and efficient method for exploiting second order Rayleigh-Schrödinger perturbation theory to approximate the correlation energy contribution to the London dispersion interaction is presented. The correlation energy is estimated as the Møller-Plesset contribution computed using single particle orbitals from hybrid exchange density functional theory as the reference state.
NASA Astrophysics Data System (ADS)
DiLabio, Gino A.; Christiansen, Phillip A.
1998-05-01
The spin-orbit energy contributions to the ground state potential energy curves for the main group hydrides, TIH through AtH are estimated by differencing multireference, single promotion, configuration interaction (MRS-CI) energies with and without the spin-orbit operator. The spin-orbit contributions are then summed into the energies determined at the λ-s MRSD-CI level (both single and double promotions). The agreement between the resultant curves and those obtained using intermediate coupling MRSD-CI is within 1.2 kcal/mol over a range of internuclear separations. This suggests that, contrary to previous arguments, spin-orbit coupling and correlation energies are very nearly separable for the main group hydride ground states. Furthermore, the computational effort expended by this separate evaluation is up to 12 times less than that for a comparable intermediate coupling CI. The analysis of some properties of these hydrides indicates that bond length shifts due to spin-orbit coupling are small (0.03 Å) while harmonic vibrational frequencies decrease by up to 9%. Dissociation energies are predicted to change considerably in the presence of the operator in agreement with previous findings.
CAP,JEROME S.; TRACEY,BRIAN
1999-11-15
Aerospace payloads, such as satellites, are subjected to vibroacoustic excitation during launch. Sandia's MTI satellite has recently been certified to this environment using a combination of base input random vibration and reverberant acoustic noise. The initial choices for the acoustic and random vibration test specifications were obtained from the launch vehicle Interface Control Document (ICD). In order to tailor the random vibration levels for the laboratory certification testing, it was necessary to determine whether vibration energy was flowing across the launch vehicle interface from the satellite to the launch vehicle or the other direction. For frequencies below 120 Hz this issue was addressed using response limiting techniques based on results from the Coupled Loads Analysis (CLA). However, since the CLA Finite Element Analysis FEA model was only correlated for frequencies below 120 Hz, Statistical Energy Analysis (SEA) was considered to be a better choice for predicting the direction of the energy flow for frequencies above 120 Hz. The existing SEA model of the launch vehicle had been developed using the VibroAcoustic Payload Environment Prediction System (VAPEPS) computer code [1]. Therefore, the satellite would have to be modeled using VAPEPS as well. As is the case for any computational model, the confidence in its predictive capability increases if one can correlate a sample prediction against experimental data. Fortunately, Sandia had the ideal data set for correlating an SEA model of the MTI satellite--the measured response of a realistic assembly to a reverberant acoustic test that was performed during MTI's qualification test series. The first part of this paper will briefly describe the VAPEPS modeling effort and present the results of the correlation study for the VAPEPS model. The second part of this paper will present the results from a study that used a commercial SEA software package [2] to study the effects of in-plane modes and to
NASA Astrophysics Data System (ADS)
Mrozik, Michael K.; Pitzer, Russell M.; Bursten, Bruce E.
2010-06-01
Since the identification of f-orbital contribution to the bonding in PaO+, investigations into Pa cations have hoped to characterize as many of the electronic states possible.1 Electronic states of the Pan+ (n=0-4) ions have been investigated using multi-reference spin-orbit configuration interaction (MR-SOCI). Initial investigations using Dunning style correlation consistent double-{ζ} basis sets are re-examined with a larger triple-{ζ} basis, with the hope of supporting the order of electronic states. Calculations using Hartree-Fock and CI calculations on the neutral atom did not produce the known order of states. A case study was deemed necessary on similar electron configurations present in the low energy states of Pa2+ more specifically those generated from the 5f26d1 and 5f16d2 configurations. Comparison in the Pa2+ ion is complicated by the lack of experimental results, but the states are presumed to be similar sequence as those in the neutral atom, with the addition of two electrons in the 7s shell. In evaluating the impact of inclusion of the outer core, calculations including valence-outer core correlation were completed for the 5d, 6s, and 6p shells of the Pa2+ ion. The magnitude of these individual shell correlation calculations will allow for identification of the energy level shifts associated with even and odd configurations, better describing the energy order in both the Pa2+ ion case study and for the neutral Pa atom. Upon completion of this aspect of the Pa neutral atom study, the knowledge of the energy levels in the Pan+ (n=0-4) family of ions will be greatly expanded, and may yield a model for future studies of atomic actinide systems. Gibson {et al.} Organometallics 2007, 26, 3947-3956.
Long range rapidity correlations and jet production in high energy nuclear collisions
STAR Collaboration; Abelev, Betty
2010-07-05
The STAR Collaboration at RHIC presents a systematic study of high transverse momentum charged di-hadron correlations at small azimuthal pair separation {Delta}{phi}, in d+Au and central Au+Au collisions at {radical}s{sub NN} = 200 GeV. Significant correlated yield for pairs with large longitudinal separation {Delta}{eta} is observed in central Au+Au, in contrast to d+Au collisions. The associated yield distribution in {Delta}{eta} x {delta}{phi} can be decomposed into a narrow jet-like peak at small angular separation which has a similar shape to that found in d+Au collisions, and a component which is narrow in {Delta}{phi} and depends only weakly on {Delta}{eta}, the 'ridge'. Using two systematically independent analyses, finite ridge yield is found to persist for trigger p{sub t} > 6 GeV/c, indicating that it is correlated with jet production. The transverse momentum spectrum of hadrons comprising the ridge is found to be similar to that of bulk particle production in the measured range (2 < p{sub t} < 4 GeV/c).
NASA Astrophysics Data System (ADS)
Holzmann, Wolf
2002-04-01
In a recent publication [1], the PHENIX collaboration has reported on the transverse momentum spectra for charged hadrons and for neutral pions in the range 1 < pT < 5 GeV/c. The spectra from peripheral nuclear collisions were found to be consistent with a simple scaling of the spectra from p+p collisions by the average number of nucleon-nucleon binary collisions. In contrast, the spectra from central collisions appeared to be significantly suppressed when compared to that from peripheral collisions as well as to the scaled p+p expectation. These observations have been interpreted as an important signature for jet quenching( [1],[2]) in central Au + Au collisions at RHIC. Significant jet production should also lead to discernable multi-particle correlations. Thus, the study of such correlations and their possible modification due to quenching, offers a promising opportunity for the investigation and study of QGP formation at RHIC. The multiparticle correlation analysis technique will be presented in conjunction with possible results for Au + Au data (sqrt(s) = 200GeV/c) obtained with the PHENIX detector at RHIC [1] Adcox et al., Phys. Rev. Lett. 88, 022301 (2001) [2] M. Gyulassy and X.-N. Wang, Nucl. Phys. B420, 583 (1994)X.-N. Wang, M.Gyulassy and M. Pluemer, Phys. Rev. D 51, 3436 (1995)
The multiplicity and the spectra of secondaries correlated with the leading particle energy
NASA Technical Reports Server (NTRS)
Kruglov, N. A.; Proskuryakov, A. S.; Sarycheva, L. I.; Smirnova, L. N.
1985-01-01
The spectra of leading particles of different nature in pp-collisions at E sub 0 = 33 GeV are obtained. The multiplicities and the spectra of secondaries, mesons, gamma-quanta, lambda and lambda-hyperons and protons for different leading particle energy ranges are determined.
NASA Astrophysics Data System (ADS)
Werner, Hans-Joachim
2016-11-01
The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.
Werner, Hans-Joachim
2016-11-28
The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.
NASA Astrophysics Data System (ADS)
Khan, Suffian; Johnson, Duane
2010-03-01
To perform electronic-structure calculations for inherently large systems, such as a quantum dots with heterogeneous interfaces, we must perform the calculations over very large unit cells (10^4 to 10^8 atoms). KKR methods typically solve for G by direct inversion G-1, with known analytic form. Using a screened, k-space hybrid KKR, we solve Dyson's equation for the Green's function using a reference state via G = Gref [ I - (t - tref) Gref]-1, scattering matrices t and tref are known and the non-Hermitian tensor Gref is chosen for convenience and sparsity [1]. The approach is O(N) for bandgap materials, whereas it is O(N^2) for metals but with a potentially large prefactor. We use Krylov-space solvers to reduce storage and exploit known symmetries. Parallel iterative and energy contour solves are made also. We explore the numerical efficiency and scaling versus atoms per unit cells. [1] Smirnov and Johnson, Comp! ^1Phys. Comm. 148, 74-80 (2002).
NASA Astrophysics Data System (ADS)
Khan, Suffian; Alam, Aftab; Johnson, Duane
2009-03-01
To perform electronic-structure calculations for inherently large systems, such as a quantum dots or interfaces like domain walls, we must perform the calculations over very large unit cells (10^4 to 10^8 atoms). For the inverse Green's function G-1, KKR methods typically solve for G by direct inversion. Using a screened, k-space hybrid KKR, we solve Dyson's equation for the Green's function using a reference state via G = Gref [ I - (t - tref) Gref]-1, scattering matrices t and tref are known and the non-Hermitian tensor Gref is chosen for convenience and sparsity [1]. The approach is O(N) for bandgap materials, whereas it is O(N^2) for metals but with a potentially large prefactor. Based upon Sparse Approximate Inverse (or SPAI) technique [2], we generalize the algorithm for complex, non-Hermitian matrices, then use the method as a preconditioner for the inversion to reduce the iteration counts (hence, reduce the prefactor) of the iterative Krylov-space inverses, such as TFQMR, to address large-scale metallic systems. Parallel iterative and energy contour solves are made also. We explore the numerical efficiency and scaling versus atoms per unit cells. [1] Smirnov and Johnson, Comp. Phys. Comm. 148, 74-80 (2002). [2] Grote and Huckle, SIAM J. Sci. Comput. 18, 8
Multicontextual correlates of energy-dense, nutrient-poor snack food consumption by adolescents.
Larson, Nicole; Miller, Jonathan M; Eisenberg, Marla E; Watts, Allison W; Story, Mary; Neumark-Sztainer, Dianne
2017-05-01
Frequent consumption of energy-dense, nutrient-poor snack foods is an eating behavior of public health concern. This study was designed to inform strategies for reducing adolescent intake of energy-dense snack foods by identifying individual and environmental influences. Surveys were completed in 2009-2010 by 2540 adolescents (54% females, mean age = 14.5 ± 2.0, 80% nonwhite) in Minneapolis-St. Paul, Minnesota schools. Daily servings of energy-dense snack food was assessed using a food frequency questionnaire that asked about consumption of 21 common snack food items, such as potato chips, cookies, and candy. Data representing characteristics of adolescents' environments were collected from parents/caregivers, friends, school personnel, Geographic Information System sources, and a content analysis of favorite television shows. Linear regression was used to examine relationships between each individual or environmental characteristic and snack food consumption in separate models and also to examine relationships in a model including all of the characteristics simultaneously. The factors found to be significantly associated with higher energy-dense snack food intake represented individual attitudes/behaviors (e.g., snacking while watching television) and characteristics of home/family (e.g., home unhealthy food availability), peer (friends' energy-dense snack food consumption), and school (e.g., student snack consumption norms) environments. In total, 25.5% of the variance in adolescents' energy-dense snack food consumption was explained when factors from within each context were examined together. The results suggest that the design of interventions targeting improvement in the dietary quality of adolescents' snack food choices should address relevant individual factors (e.g., eating while watching television) along with characteristics of their home/family (e.g., limiting the availability of unhealthy foods), peer (e.g., guiding the efforts of a peer leader in
NASA Astrophysics Data System (ADS)
Garg, Prakhar
2016-12-01
The RHIC Beam Energy Scan focuses on mapping the QCD phase diagram and pinpointing the location of a possible critical end point. Bose-Einstein correlations and event-by-event fluctuations of conserved quantities, measured as a function of centrality and collision energy, are promising tools in these studies. Recent lattice QCD and statistical thermal model calculations predict that higher-order cumulants of the fluctuations are sensitive indicators of the phase transition. Products of these cumulants can be used to extract the freeze-out parameters [A. Bazavov et al., Phys. Rev. Lett. 109, 192302 (2012)] and to locate the critical point [M. A. Stephanov, K. Rajagopal and E. V. Shuryak, Phys. Rev. D 60, 114028 (1999)]. Two-pion interferometry measurements are predicted to be sensitive to potential softening of the equation of state and prolonged emission duration close to the critical point [S. Pratt, Phys. Rev. Lett. 53, 1219 (1984)]. We present recent PHENIX results on fluctuations of net-charge using high-order cumulants and their products in Au+Au collisions at √{sNN} = 7.7- 200 GeV, and measurement of two-pion correlation functions and emission-source radii in Cu+Cu and Au+Au collisions at several beam energies. The extracted source radii are compared to previous measurements at RHIC and LHC in order to study energy dependence of the specific quantities sensitive to expansion velocity and emission duration. Implications for the search of a critical point and baryon chemical potentials at various collision energies are discussed.
NASA Astrophysics Data System (ADS)
Kovalenko, Vladimir
2017-03-01
Long-range multiplicity correlations in intervals separated in pseudorapidity and azimuth are studied in the framework of string fusion approach. We applied a Monte Carlo model, in which the string configurations in the transverse plane and rapidity are simulating event-by-event. The string interaction is realized in the lattice string fusion approach with introduction of a grid in the transverse plane. We assumed that the azimuthal anisotropy of particle production is caused by parton energy loss traveling trough the media formed by clusters of fused strings : Δpt/Δx = -α(pt √η)2/3, where η is a string density. In the cellular approach the Bresenham's line algorithm has been applied. It is obtained that in AA collisions, the parton energy loss seems to play considerable role, in particular, by providing large contribution to the correlation of mean transverse momentum with multiplicity. The developed approach provides non-zero values flows in p-Pb collisions at LHC energies and produces the pattern similar to the one of the experimental di-hadron analysis.
Correlation of Resonance Charge Exchange Cross-Section Data in the Low-Energy Range
NASA Technical Reports Server (NTRS)
Sheldon, John W.
1962-01-01
During the course of a literature survey concerning resonance charge exchange, an unusual degree of agreement was noted between an extrapolation of the data reported by Kushnir, Palyukh, and Sena and the data reported by Ziegler. The data of Kushnir et al. are for ion-atom relative energies from 10 to 1000 ev, while the data of Ziegler are for a relative energy of about 1 ev. Extrapolation of the data of Kushnir et al. was made in accordance with Holstein's theory, 3 which is a combination of time-dependent perturbation methods and classical orbit theory. The results of this theory may be discussed in terms of a critical impact parameter b(sub c).
Hadron Correlations at Energies from GeV to TeV
NASA Astrophysics Data System (ADS)
Kittel, W.
One of the central issues in High Energy Physics is the close interchange between Theory and Experiment. Ever since I know Andrzej Bia{\\l}as, I know him as one of the theorists most interested in experimental data. This has naturally led to continuous fruitful contacts. Even though we have been working somehow together since about 1968, we so far have only one single publication in common. This was back in 1969 and it was on means to efficiently study what we then called (exclusive) Multihadron Final States. At that time this meant 3- or at best 4-particle final states of two-hadron collisions at cms energies of some 4 GeV (not TeV!). The field of multiparticle dynamics was in fact the domain of Polish high-energy physicists. The first of a very successful (and still lasting) series of annual International Symposia on Multiparticle Dynamics was organized in Paris in 1970, but essentially by Polish physicists. Andrzej himself was not attending, but it was he who organized the third in these series in (of course) Zakopane. Since heavy ion-collisions, another field of major interest for Andrzej, will be covered by others, I here will restrict myself mainly to the collisions of two elementary particles.
NASA Astrophysics Data System (ADS)
Kovalenko, V. N.
2013-10-01
The soft part of proton-proton interaction is considered within a phenomenological model that involves the formation of color strings. Under the assumption that an elementary collision is associated with the interaction of two color dipoles, the total inelastic cross section and the multiplicity of charged particles are estimated in order to fix model parameters. Particular attention is given to modeling of exclusive parton distributions with allowance for the energy-conservation law and for fixing the center of mass, which are necessary for describing correlations. An algorithm that describes the fusion of strings in the transverse plane and which takes into account their finite rapidity width is developed. The influence of string-fusion effects on long-range correlations is found within this mechanism.
NASA Astrophysics Data System (ADS)
Corradi, Lorenzo
2015-10-01
Excitation functions of one- and two-neutron transfer channels have been measured for the 96Zr+40Ca and 116Sn+60Ni systems at bombarding energies ranging from the Coulomb barrier to ˜25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.
Sharpening Low-Energy, Standard-Model Tests via Correlation Coefficients in Neutron {beta} Decay
Gardner, S.; Zhang, C.
2001-06-18
The correlation coefficients a , A , and B in neutron {beta} decay are proportional to the ratio of the axial-vector-to-vector weak coupling constants, g{sub A}/g{sub V} , to leading recoil order. With the advent of the next generation of neutron-decay experiments, the recoil-order corrections to these expressions become experimentally accessible, admitting a plurality of standard model (SM) tests. The measurement of both a and A , e.g., allows one to test the conserved-vector-current (CVC) hypothesis and to search for second-class currents (SCC) independently. The anticipated precision of these measurements suggests that the bounds on CVC violation and SCC from studies of nuclear {beta} decay can be qualitatively bettered.
NASA Astrophysics Data System (ADS)
Lutz, Oliver M. D.; Rode, Bernd M.; Bonn, Günther K.; Huck, Christian W.
2014-10-01
This paper discusses the quality and feasibility of highly correlated ab initio techniques in a vibrational self-consistent field (VSCF) approach using acetonitrile as a model system. The topical renormalized coupled-cluster technique exploiting the similarity-transformed Hamiltonian's left eigenstates (i.e. CR-CC(2,3)) is investigated alongside the well-known Hartree-Fock (HF), Møller-Plesset second-order perturbation theory (MP2) and coupled cluster (CCSD(T)) methods. The inclusion of mode triple interactions is discussed and it is found that the use of an effective core potential (ECP) serves as a viable compromise during the highly demanding task of computing such contributions, thus enabling a grid-based evaluation of three mode interaction terms with coupled cluster techniques also for larger molecules. In this context, a previously proposed reduced coupling scheme [1] is investigated, confirming the applicability of this technique to a system exhibiting a rather complex electronic structure. A combination of Ahlrichs' triple-ζ valence polarized (TZVP) basis set with Dunning's set of core-valence correlation functions is found to deliver results in good agreement with experiment while being computationally very feasible. Since CH3CN exhibits four degenerate vibrational degrees of freedom, it serves as an ideal model system for critically assessing the qualities of the degenerate second-order perturbation theory corrected (DPT2) VSCF technique. Besides fundamental vibrations, a thorough investigation of overtone transitions and combination bands is conducted by means of comparing the results to both available and newly recorded experimental data.
NASA Astrophysics Data System (ADS)
Piskur, J.; Borg, L.; Stupnik, A.; Leisch, M.; Ernst, W. E.; Holst, B.
2008-05-01
In this paper the correlation between the kinetic energy of helium atoms and the probability of field ionization is investigated by exploiting the narrow velocity distribution of supersonic molecular beams. Field ionization measurements were carried out on supersonic helium beams at 298 K and 95 K corresponding to energies of about 65 meV and 20 meV, respectively, for the individual atoms. The field ionization was performed with a tungsten tip, radius of curvature 12 nm, kept at room temperature. The ionization probability was found to increase by about a factor 10 when the beam was cooled from 298 K to 95 K. The results presented in this paper are of importance for improving the understanding of field ionization and for the development of a new detector for helium and other molecular beams.
Rezaee, Mohammad Hunting, Darel J.; Sanche, Léon
2014-07-15
Purpose: The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods: Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by{sup 125}I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results: For a single decay of{sup 125}I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm{sup 3} volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions: Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should
Doi, Takahiro; Fujita, Ichiro
2014-01-01
Three-dimensional visual perception requires correct matching of images projected to the left and right eyes. The matching process is faced with an ambiguity: part of one eye's image can be matched to multiple parts of the other eye's image. This stereo correspondence problem is complicated for random-dot stereograms (RDSs), because dots with an identical appearance produce numerous potential matches. Despite such complexity, human subjects can perceive a coherent depth structure. A coherent solution to the correspondence problem does not exist for anticorrelated RDSs (aRDSs), in which luminance contrast is reversed in one eye. Neurons in the visual cortex reduce disparity selectivity for aRDSs progressively along the visual processing hierarchy. A disparity-energy model followed by threshold nonlinearity (threshold energy model) can account for this reduction, providing a possible mechanism for the neural matching process. However, the essential computation underlying the threshold energy model is not clear. Here, we propose that a nonlinear modification of cross-correlation, which we term “cross-matching,” represents the essence of the threshold energy model. We placed half-wave rectification within the cross-correlation of the left-eye and right-eye images. The disparity tuning derived from cross-matching was attenuated for aRDSs. We simulated a psychometric curve as a function of graded anticorrelation (graded mixture of aRDS and normal RDS); this simulated curve reproduced the match-based psychometric function observed in human near/far discrimination. The dot density was 25% for both simulation and observation. We predicted that as the dot density increased, the performance for aRDSs should decrease below chance (i.e., reversed depth), and the level of anticorrelation that nullifies depth perception should also decrease. We suggest that cross-matching serves as a simple computation underlying the match-based disparity signals in stereoscopic depth
Doi, Takahiro; Fujita, Ichiro
2014-01-01
Three-dimensional visual perception requires correct matching of images projected to the left and right eyes. The matching process is faced with an ambiguity: part of one eye's image can be matched to multiple parts of the other eye's image. This stereo correspondence problem is complicated for random-dot stereograms (RDSs), because dots with an identical appearance produce numerous potential matches. Despite such complexity, human subjects can perceive a coherent depth structure. A coherent solution to the correspondence problem does not exist for anticorrelated RDSs (aRDSs), in which luminance contrast is reversed in one eye. Neurons in the visual cortex reduce disparity selectivity for aRDSs progressively along the visual processing hierarchy. A disparity-energy model followed by threshold nonlinearity (threshold energy model) can account for this reduction, providing a possible mechanism for the neural matching process. However, the essential computation underlying the threshold energy model is not clear. Here, we propose that a nonlinear modification of cross-correlation, which we term "cross-matching," represents the essence of the threshold energy model. We placed half-wave rectification within the cross-correlation of the left-eye and right-eye images. The disparity tuning derived from cross-matching was attenuated for aRDSs. We simulated a psychometric curve as a function of graded anticorrelation (graded mixture of aRDS and normal RDS); this simulated curve reproduced the match-based psychometric function observed in human near/far discrimination. The dot density was 25% for both simulation and observation. We predicted that as the dot density increased, the performance for aRDSs should decrease below chance (i.e., reversed depth), and the level of anticorrelation that nullifies depth perception should also decrease. We suggest that cross-matching serves as a simple computation underlying the match-based disparity signals in stereoscopic depth perception.
Intralayer doping effects on the high-energy magnetic correlations in NaFeAs
Pelliciari, Jonathan; Huang, Yaobo; Das, Tanmoy; Dantz, Marcus; Bisogni, Valentina; Velasco, Paul Olalde; Strocov, Vladimir N.; Xing, Lingyi; Wang, Xiancheng; Jin, Changqing; Schmitt, Thorsten
2016-04-26
We used resonant inelastic x-ray scattering (RIXS) and dynamical susceptibility calculations to study the magnetic excitations in NaFe_{1$-$x}Co_{x}As ( x=0 , 0.03, and 0.08). Despite a relatively low ordered magnetic moment, collective magnetic modes are observed in parent compounds (x=0) and persist in optimally (x= 0.03) and overdoped (x = 0.08) samples. Their magnetic bandwidths are unaffected by doping within the range investigated. High-energy magnetic excitations in iron pnictides are robust against doping and present irrespectively of the ordered magnetic moment. Nonetheless, Co doping slightly reduces the overall magnetic spectral weight, differently from previous studies on hole-doped BaFe_{2}As_{2} , where it was observed constant. Finally, we demonstrate that the doping evolution of magnetic modes is different for the dopants being inside or outside the Fe-As layer.
Time correlations between low and high energy gamma rays from discrete sources
NASA Technical Reports Server (NTRS)
Ellsworth, R. W.
1995-01-01
Activities covered the following areas: (1) continuing analysis of the Cygnus Experiment data on the shadowing of cosmic rays by the moon and sun, which led to a direct confirmation of the angular resolution of the CYGNUS EAS array; and (2) development of analysis methods for the daily search overlapping with EGRET targets. To date, no steady emission of ultrahigh energy (UHE) gamma rays from any source has been detected by the Cygnus Experiment, but some evidence for sporadic emission had been found. Upper limits on steady fluxes from 49 sources in the northern hemisphere have been published. In addition, a daily search of 51 possible sources over the interval April 1986 to June 1992 found no evidence for emission. From these source lists, four candidates were selected for comparison with EGRET data.
Intralayer doping effects on the high-energy magnetic correlations in NaFeAs
Pelliciari, Jonathan; Huang, Yaobo; Das, Tanmoy; ...
2016-04-26
We used resonant inelastic x-ray scattering (RIXS) and dynamical susceptibility calculations to study the magnetic excitations in NaFe1$-$xCoxAs ( x=0 , 0.03, and 0.08). Despite a relatively low ordered magnetic moment, collective magnetic modes are observed in parent compounds (x=0) and persist in optimally (x= 0.03) and overdoped (x = 0.08) samples. Their magnetic bandwidths are unaffected by doping within the range investigated. High-energy magnetic excitations in iron pnictides are robust against doping and present irrespectively of the ordered magnetic moment. Nonetheless, Co doping slightly reduces the overall magnetic spectral weight, differently from previous studies on hole-doped BaFe2As2 , wheremore » it was observed constant. Finally, we demonstrate that the doping evolution of magnetic modes is different for the dopants being inside or outside the Fe-As layer.« less
Pion and kaon correlations in high energy heavy-ion collisions
Wolf, K.L.; Wolf, K.L.
1996-12-31
Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An upgraded multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization. 35 refs., 15 figs., 5 tabs.
Pion correlations and calorimeter design for high energy heavy ion collisions. Progress report
Wolf, K.L.
1997-04-01
Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An updated multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au + Au reaction, taken with full event characterization.
Hepatic energy metabolism correlated with pathology score in rats chronically fed ethanol
Takahasi, H.; Geoffrion, Y.; Butler, K.W.; French, S.W. )
1989-02-09
We repeatedly measured in vivo levels of hepatic phosphorylated metabolites in alcohol-fed rats using non-invasive 31P MRS to evaluate their relation to the severity of the pathologic changes of alcoholic liver disease (ALD). Five pairs of Wister rats were pair-fed with a liquid diet plus ethanol or an isocaloric amount of dextrose via an implanted intragastric tube for up to 6 months (mo). For MRS, the rats were sedated, air was provided by a face mask, and the diet was infused to maintain high blood alcohol levels. {sup 31}P MRS spectra were obtained using a CYCLOPS pulse-acquire sequence, 200 scans, and a 2s recycle delay. The inorganic phosphate (Pi)/ATP peak area ratio was found to be consistently higher in the alcohol-fed rats (E) compared to the pair-fed controls (C). The sugar phosphate/ATP ratio tended to be higher in E when compared to C. Cytosolic pH measured by the chemical shift of the Pi peak showed no significant differences between E and C. The monthly liver biopsies from E showed more severe steatosis, necrosis, and fibrosis with time of feeding and the Pi/ATP ratio was positively correlated with the scored histological changes. These results suggest that a low hepatic energetic state is associated with the progression of ALD pathology.
Correlation of energy disorder and open-circuit voltage in hybrid perovskite solar cells
Shao, Yuchuan; Yuan, Yongbo; Huang, Jinsong
2016-01-11
Organometal trihalide perovskites have been demonstrated as excellent light absorbers for high efficiency photovoltaic applications. Previous approaches to increasing the solar cell efficiency have focussed on optimisation of the grain morphology of perovskite thin films. Here, we show that the structural order of the electron-transport layers also has a significant impact on solar cell performance. We demonstrate that the power conversion efficiency of CH3NH3PbI3 planar-heterojunction photovoltaic cells increases from 17.1% to 19.4% when the energy disorder in the fullerene electron-transport layer is reduced by a simple solvent annealing process. The increase in efficiency is the result of the enhancement inmore » open-circuit voltage from 1.04 V to 1.13 V without sacrificing the short-circuit current and fill factor. Finally, these results shed light on the origin of open-circuit voltage in perovskite solar cells, and provide a new path to further increase their efficiency« less
Correlation of energy disorder and open-circuit voltage in hybrid perovskite solar cells
Shao, Yuchuan; Yuan, Yongbo; Huang, Jinsong
2016-01-11
Organometal trihalide perovskites have been demonstrated as excellent light absorbers for high efficiency photovoltaic applications. Previous approaches to increasing the solar cell efficiency have focussed on optimisation of the grain morphology of perovskite thin films. Here, we show that the structural order of the electron-transport layers also has a significant impact on solar cell performance. We demonstrate that the power conversion efficiency of CH_{3}NH_{3}PbI_{3} planar-heterojunction photovoltaic cells increases from 17.1% to 19.4% when the energy disorder in the fullerene electron-transport layer is reduced by a simple solvent annealing process. The increase in efficiency is the result of the enhancement in open-circuit voltage from 1.04 V to 1.13 V without sacrificing the short-circuit current and fill factor. Finally, these results shed light on the origin of open-circuit voltage in perovskite solar cells, and provide a new path to further increase their efficiency
Correlation of energy disorder and open-circuit voltage in hybrid perovskite solar cells
Shao, Yuchuan; Yuan, Yongbo; Huang, Jinsong
2016-01-11
Organometal trihalide perovskites have been demonstrated as excellent light absorbers for high efficiency photovoltaic applications. Previous approaches to increasing the solar cell efficiency have focussed on optimisation of the grain morphology of perovskite thin films. Here, we show that the structural order of the electron-transport layers also has a significant impact on solar cell performance. We demonstrate that the power conversion efficiency of CH3NH3PbI3 planar-heterojunction photovoltaic cells increases from 17.1% to 19.4% when the energy disorder in the fullerene electron-transport layer is reduced by a simple solvent annealing process. The increase in efficiency is the result of the enhancement inmore » open-circuit voltage from 1.04 V to 1.13 V without sacrificing the short-circuit current and fill factor. Lastly, these results shed light on the origin of open-circuit voltage in perovskite solar cells, and provide a new path to further increase their efficiency.« less
Highly correlated systems. Ionization energies of first row transition metals Sc--Zn
Raghavachari, K.; Trucks, G. W.
1989-08-15
The low-lying ionization potentials of the first row transition metal atoms Sc--Zn are calculated using fourth-order Moller--Plesset perturbation theory (MP4) and quadratic configuration interaction (QCI) techniques with large /ital spd/ and /ital spdf/ basis sets. Two ionic states have been considered for each atom yielding a total of 20 different ionization processes which we have included in this study. For Sc/sup +/--Cu/sup +/, the ionic states considered have /ital d//sup /ital n/s//sup 1/ and /ital d//sup /ital n/+1/ orbital occupations and for Zn/sup +/, the /ital d//sup 10//ital s1/ and /ital d//sup 9//ital s2/ states were studied. The MP4 method accurately reproduces the ionization potentials of Sc--Fe, but is found to be inadequate for Co--Zn. In contrast, the QCI technique performs uniformly for all ionization energies with a mean deviation from experiment of only 0.13 eV (with the /ital spdf/ basis set) after inclusion of relativistic corrections.
Correlation of energy disorder and open-circuit voltage in hybrid perovskite solar cells
Shao, Yuchuan; Yuan, Yongbo; Huang, Jinsong
2016-01-11
Organometal trihalide perovskites have been demonstrated as excellent light absorbers for high efficiency photovoltaic applications. Previous approaches to increasing the solar cell efficiency have focussed on optimisation of the grain morphology of perovskite thin films. Here, we show that the structural order of the electron-transport layers also has a significant impact on solar cell performance. We demonstrate that the power conversion efficiency of CH_{3}NH_{3}PbI_{3} planar-heterojunction photovoltaic cells increases from 17.1% to 19.4% when the energy disorder in the fullerene electron-transport layer is reduced by a simple solvent annealing process. The increase in efficiency is the result of the enhancement in open-circuit voltage from 1.04 V to 1.13 V without sacrificing the short-circuit current and fill factor. Lastly, these results shed light on the origin of open-circuit voltage in perovskite solar cells, and provide a new path to further increase their efficiency.
NASA Astrophysics Data System (ADS)
Kelly, Kathleen M.
Several factors are critical in determining if a wind farm has a high probability of success. These factors include wind energy potential or wind class, sales price, cost of the wind energy generated, market for selling the wind, capacity factor or efficiency of the turbines, capital investment cost, debt and financing, and governmental factors such as taxes and incentives. This research studied the critical factors of thirty-three land based wind farms in the United States with over 20 mega-watts (MW) of capacity that have become operational since 1999. The goal was to develop a simple yet effective decision model using the critical factors to predict an internal rate of return (IRR) and the impact of having a tax credit to supplement the revenue stream. The study found that there are five critical factors that are significantly correlated with the internal rate of return (IRR) of a wind farm project. The critical factors are wind potential or wind class, cost of the wind energy generated, capacity factor or efficiency of the wind turbines, cost of capital investment, and the existence of a federal production tax credit (PTC). The decision model was built using actual wind farm data and industry standards whereby a score from zero to one hundred was coded for each of values except for the production tax credit. Since all the projects qualified for the production tax credit prior to their start up, it was no longer a variable. However, without the presence of this tax credit, the data imply that the projects would not be profitable within the first ten to fifteen years of operation. The scores for each of the categories were totaled and regressed against a calculated internal rate of return. There was ninety-seven percent correlation which was supported by simulation analysis. While this model is not intended to supplant rigorous accounting and financial study, it will help quickly determine if a site has potential and save many hours of analytical work.
Avery, R.E.
1989-01-13
Measurements of two- and three-particle correlations between like-sign pions produced in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy are presented. The analysis is based on data taken during the period 1982--1986 using the TPC/2..gamma.. detector at PEP. Two-particle correlations are studied as a function of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of q/sub 0/, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the energy difference, q/sub 0/, is substantial. This observation provides evidence that the Bose-Einstein correlations are best described by a model that correctly accounts for the relativistic motion of the particle sources. Three-pion correlations are measured both by using a standard three-pion correlation function, and also by using a correlation function for which the correlations between the pairs of pions within the triplet have been subtracted. The observation of three-pion correlations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference. 56 refs.
Dual-energy micro-CT imaging of pulmonary airway obstruction: correlation with micro-SPECT
NASA Astrophysics Data System (ADS)
Badea, C. T.; Befera, N.; Clark, D.; Qi, Y.; Johnson, G. A.
2014-03-01
To match recent clinical dual energy (DE) CT studies focusing on the lung, similar developments for DE micro-CT of the rodent lung are required. Our group has been actively engaged in designing pulmonary gating techniques for micro- CT, and has also introduced the first DE micro-CT imaging method of the rodent lung. The aim of this study was to assess the feasibility of DE micro-CT imaging for the evaluation of airway obstruction in mice, and to compare the method with micro single photon emission computed tomography (micro-SPECT) using technetium-99m labeled macroaggregated albumin (99mTc-MAA). The results suggest that the induced pulmonary airway obstruction causes either atelectasis, or air-trapping similar to asthma or chronic bronchitis. Atelectasis could only be detected at early time points in DE micro-CT images, and is associated with a large increase in blood fraction and decrease in air fraction. Air trapping had an opposite effect with larger air fraction and decreased blood fraction shown by DE micro-CT. The decrease in perfusion to the hypoventilated lung (hypoxic vasoconstriction) is also seen in micro-SPECT. The proposed DE micro-CT technique for imaging localized airway obstruction performed well in our evaluation, and provides a higher resolution compared to micro-SPECT. Both DE micro-CT and micro-SPECT provide critical, quantitative lung biomarkers for image-based anatomical and functional information in the small animal. The methods are readily linked to clinical methods allowing direct comparison of preclinical and clinical results.
Yang, Mino
2014-04-14
Förster theory for the survival probability of excited chromophores is generalized to include the effects of excluded volume and orientation correlation in the molecular distribution. An analytical expression for survival probability was derived and written in terms of a few simple elementary functions. Because of the excluded volume, the survival probability exhibits exponential decay at early times and stretched exponential decay at later times. Experimental schemes to determine the size of the molecular excluded volume are suggested. With the present generalization of theory, we analyzed vibrational resonance energy transfer kinetics in neat water. Excluded volume effects prove to be important and slow down the kinetics at early times. The majority of intermolecular resonance energy transfer was found to occur with exponential kinetics, as opposed to the stretched exponential behavior predicted by Förster theory. Quantum yields of intra-molecular vibrational relaxation, intra-, and intermolecular energy transfer were calculated to be 0.413, 0.167, and 0.420, respectively.
NASA Technical Reports Server (NTRS)
Klochkov, D.; Doroshenko, V.; Santangelo, A.; Staubert, R.; Ferrigno, C.; Kretschmar, P.; Caballero, I.; Wilms, J.; Kreykenbohm, I.; Pottschmidt, I.; Rothschild, R. E.; Pilhlhofer, G.
2012-01-01
Context. X-ray spectra of many accreting pulsars exhibit significant variations as a function of flux and thus of mass accretion rate. In some of these pulsars, the centroid energy of the cyclotron line(s), which characterizes the magnetic field strength at the site of the X-ray emission, has been found to vary systematically with flux. Aims. GX304-1 is a recently established cyclotron line source with a line energy around 50 keV. Since 2009, the pulsar shows regular outbursts with the peak flux exceeding one Crab. We analyze the INTEGRAL observations of the source during its outburst in January-February 2012. Methods. The observations covered almost the entire outburst, allowing us to measure the source's broad-band X-my spectrum at different flux levels. We report on the variations in the spectral parameters with luminosity and focus on the variations in the cyclotron line. Results. The centroid energy of the line is found to be positively correlated with the luminosity. We interpret this result as a manifestation of the local sub-Eddington (sub-critical) accretion regime operating in the source.
NASA Astrophysics Data System (ADS)
Crespillo, M. L.; Agulló-López, F.; Zucchiatti, A.
2017-03-01
An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO3 crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.
Mani, B. K.; Angom, D.; Latha, K. V. P.
2009-12-15
We have carried out a detailed and systematic study of the correlation energies of inert gas atoms Ne, Ar, Kr, and Xe using relativistic many-body perturbation theory and relativistic coupled-cluster theory. In the relativistic coupled-cluster calculations, we implement perturbative triples and include these in the correlation energy calculations. We then calculate the dipole polarizability of the ground states using perturbed coupled-cluster theory.
NASA Astrophysics Data System (ADS)
Rangel, T.; Caliste, D.; Genovese, L.; Torrent, M.
2016-11-01
We present a Projector Augmented-Wave (PAW) method based on a wavelet basis set. We implemented our wavelet-PAW method as a PAW library in the ABINIT package [http://www.abinit.org] and into BigDFT [http://www.bigdft.org]. We test our implementation in prototypical systems to illustrate the potential usage of our code. By using the wavelet-PAW method, we can simulate charged and special boundary condition systems with frozen-core all-electron precision. Furthermore, our work paves the way to large-scale and potentially order- N simulations within a PAW method.
Azagba, Sunday; Langille, Don
2013-01-01
Background An emerging body of research has reported high consumption of alcohol mixed with energy drinks among young adults, particularly college students. However, little is known about adolescents’ consumption of these drinks. The purpose of this study was to determine the prevalence of consumption of alcohol mixed with energy drinks and to examine its correlates among Canadian high school students. Methods We used a nationally representative sample of 36 155 Canadian students in grades 7 to 12 who participated in the 2010/2011 Youth Smoking Survey. Results About 20% of Canadian high school students reported consuming alcohol mixed with energy drinks in the last year, with considerable variation across provinces. Multivariate logistic regression analyses showed that the odds of consumption of these drinks were higher among students in lower grades (grades 7 and 8) and among students who identified their ethnicity as black or “other.” Consumption of alcohol mixed with energy drinks was positively associated with substance use (current smoking [adjusted odds ratio (OR) 1.52, 95% confidence interval (CI) 1.19–1.95], past-year heavy drinking [adjusted OR 3.41, 95% CI 2.84–4.09] and marijuana use [adjusted OR 2.29, 95% CI 1.90–2.76]), absence from school, participation in school team sports and having more weekly spending money. Students who felt more connected to school and had an academic average of 70% or higher were less likely to consume alcohol mixed with energy drinks. Interpretation The consumption of alcohol mixed with energy drinks is an emerging public health concern. Consumption of these drinks is substantial among Canadian high school students and can lead to many potential harms, both acute (e.g., injury) and long term (e.g., increased alcohol dependence). Our findings highlight the need for further research into the long-term effects of consumption of alcohol mixed with energy drinks among young people, as well as the development of
Gutsev, G L; Weatherford, C W; Belay, K G; Ramachandran, B R; Jena, P
2013-04-28
The electronic and geometrical structures of the M12 and M13 clusters where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn along with their singly negatively and positively charged ions are studied using all-electron density functional theory within the generalized gradient approximation. The geometries corresponding to the lowest total energy states of singly and negatively charged ions of V13, Mn12, Co12, Ni13, Cu13, Zn12, and Zn13 are found to be different from the geometries of the corresponding neutral parents. The computed ionization energies of the neutrals, vertical electron detachment energies from the anions, and energies required to remove a single atom from the M13 and M13(+) clusters are in good agreement with experiment. The change in a total spin magnetic moment of the cation or anion with respect to a total spin magnetic moment of the corresponding neutral is consistent with the one-electron model in most cases, i.e., they differ by ±1.0 μ(B). Exceptions are found only for Sc12(-), Ti12(+), Mn12(-), Mn12(+), Fe12(-), Fe13(+), and Co12(+).
Li, Meimei; Almer, Jonathan D.; Yang, Yong; Tan, Lizhen
2016-01-01
This report provides a summary of research activities on understanding microstructure – property correlation in reactor materials using in situ high-energy X-rays. The report is a Level 2 deliverable in FY16 (M2CA-13-IL-AN_-0403-0111), under the Work Package CA-13-IL-AN_- 0403-01, “Microstructure-Property Correlation in Reactor Materials using in situ High Energy Xrays”, as part of the DOE-NE NEET Program. The objective of this project is to demonstrate the application of in situ high energy X-ray measurements of nuclear reactor materials under thermal-mechanical loading, to understand their microstructure-property relationships. The gained knowledge is expected to enable accurate predictions of mechanical performance of these materials subjected to extreme environments, and to further facilitate development of advanced reactor materials. The report provides detailed description of the in situ X-ray Radiated Materials (iRadMat) apparatus designed to interface with a servo-hydraulic load frame at beamline 1-ID at the Advanced Photon Source. This new capability allows in situ studies of radioactive specimens subject to thermal-mechanical loading using a suite of high-energy X-ray scattering and imaging techniques. We conducted several case studies using the iRadMat to obtain a better understanding of deformation and fracture mechanisms of irradiated materials. In situ X-ray measurements on neutron-irradiated pure metal and model alloy and several representative reactor materials, e.g. pure Fe, Fe-9Cr model alloy, 316 SS, HT-UPS, and duplex cast austenitic stainless steels (CASS) CF-8 were performed under tensile loading at temperatures of 20-400°C in vacuum. A combination of wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and imaging techniques were utilized to interrogate microstructure at different length scales in real time while the specimen was subject to thermal-mechanical loading. In addition, in situ X-ray studies were
NASA Astrophysics Data System (ADS)
Appannababu, S.; Cinausero, M.; Marchi, T.; Gramegna, F.; Prete, G.; Bermudez, J.; Fabris, D.; Collazuol, G.; Saxena, A.; Nayak, B. K.; Kailas, S.; Bruno, M.; Morelli, L.; Gelli, N.; Piantelli, S.; Pasquali, G.; Barlini, S.; Valdré, S.; Vardaci, E.; Sajo-Bohus, L.; Degerlier, M.; Jhingan, A.; Behera, B. R.; Kravchuk, V. L.
2016-10-01
The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction +208Pb 50Ti at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf (Z =104 ) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of 4.5 ×10-20 s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of 258Rf. The extrapolated value of 4.7 ±1.4 is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with Z =116 and Z =124 .
Correlated blinking via time dependent energy transfer in single CdSe quantum dot-dye nanoassemblies
NASA Astrophysics Data System (ADS)
Gerlach, Frank; Täuber, Daniela; von Borczyskowski, Christian
2013-05-01
Optical confocal spectroscopy on self-assembled single nanoassemblies from CdSe/ZnS quantum dots (QD) and perylene diimide dye molecules demonstrates efficient Förster resonance energy transfer (FRET). Intramolecular dynamics of the flexible dye molecule change the FRET efficiency in course of the detection period of several minutes. This can be followed by correlated observations of luminescence intensities and related spectral shifts of both constituents. Contrary to several experiments on similar assemblies, the FRET efficiencies are by almost one order of magnitude larger in the non-polar liquid solvent TEHOS as compared e.g. to toluene. Experimental and theoretically expected efficiencies are in close agreement with each other.
NASA Astrophysics Data System (ADS)
Mackowiak-Pawlowska, Maja
2016-12-01
The aim of the NA61/SHINE strong interaction program is to explore the phase diagram of strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of strongly interacting matter. These goals are pursued by performing a beam momentum (13A - 158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La) scan. This contribution presents results on transverse momentum and multiplicity fluctuations from the Be+Be and p+p energy scan. Also, results on two-particle correlations in pseudorapidity and azimuthal angle obtained in p+p interactions will be shown. The influence of conservation laws and resonance decays on multiplicity and chemical fluctuations of identified particles in p+p interactions will be discussed. Obtained results will be compared with data from other experiments and with model predictions.
Chilingarian, A.; Daryan, A.; Arakelyan, K.; Hovhannisyan, A.; Mailyan, B.; Melkumyan, L.; Hovsepyan, G.; Chilingaryan, S.; Reymers, A.; Vanyan, L.
2010-08-15
The Aragats Space Environmental Center facilities continuously measure fluxes of neutral and charged secondary cosmic ray incidents on the Earth's surface. Since 2003 in the 1-minute time series we have detected more than 100 enhancements in the electron, gamma ray, and neutron fluxes correlated with thunderstorm activities. During the periods of the count rate enhancements, lasting tens of minutes, millions of additional particles were detected. Based on the largest particle event of September 19, 2009, we show that our measurements support the existence of long-lasting particle multiplication and acceleration mechanisms in the thunderstorm atmosphere. For the first time we present the energy spectra of electrons and gamma rays from the particle avalanches produced in the thunderstorm atmosphere, reaching the Earth's surface.
NASA Astrophysics Data System (ADS)
Havu, Vile; Blum, Volker; Scheffler, Matthias
2007-03-01
Numeric atom-centered local orbitals (NAO) are efficient basis sets for all-electron electronic structure theory. The locality of NAO's can be exploited to render (in principle) all operations of the self-consistency cycle O(N). This is straightforward for 3D integrals using domain decomposition into spatially close subsets of integration points, enabling critical computational savings that are effective from ˜tens of atoms (no significant overhead for smaller systems) and make large systems (100s of atoms) computationally feasible. Using a new all-electron NAO-based code,^1 we investigate the quantitative impact of exploiting this locality on two distinct classes of systems: Large light-element molecules [Alanine-based polypeptide chains (Ala)n], and compact transition metal clusters. Strict NAO locality is achieved by imposing a cutoff potential with an onset radius rc, and exploited by appropriately shaped integration domains (subsets of integration points). Conventional tight rc<= 3å have no measurable accuracy impact in (Ala)n, but introduce inaccuracies of 20-30 meV/atom in Cun. The domain shape impacts the computational effort by only 10-20 % for reasonable rc. ^1 V. Blum, R. Gehrke, P. Havu, V. Havu, M. Scheffler, The FHI Ab Initio Molecular Simulations (aims) Project, Fritz-Haber-Institut, Berlin (2006).
NASA Astrophysics Data System (ADS)
Dadykin, V. L.; Zatsepin, G. T.; Korol'Kova, E. V.; Korchagin, P. V.; Kudriavtsev, V. A.
1991-04-01
Observation data obtained by the LSD underground detector near Mont Blanc over the period February 10 - July 1, 1987, are analyzed for possible time correlations between all events with an energy over 5 MeV detected during this period. Nine pairs of correlated pulses (muons and low-energy pulses with a time interval of 2 s) are identified during the period from 5:42 to 10:13 UT on February 23, 1987 (i.e., around the time of the optical burst CH 1987A). The result indicates a possible relation between the time correlation of the pulses and the burst.
NASA Astrophysics Data System (ADS)
Wang, Jeen-Hwa
2013-12-01
The correlation of the scaled energy, ê = E s/ M 0, versus earthquake magnitude, M s, is studied based on two models: (1) Model 1 based on the use of the time function of the average displacements, with a ω -2 source spectrum, across a fault plane; and (2) Model 2 based on the use of the time function of the average displacements, with a ω -3 source spectrum, across a fault plane. For the second model, there are two cases: (a) As τ ≒ T, where τ is the rise time and T the rupture time, lg( ê) ~ - M s; and (b) As τ ≪ T, lg( ê) ~ -(1/2) M s. The second model leads to a negative value of ê. This means that Model 2 cannot work for studying the present problem. The results obtained from Model 1 suggest that the source model is a factor, yet not a unique one, in controlling the correlation of ê versus M s.
Sheng, WC; Myint, M; Chen, JGG; Yan, YS
2013-05-01
The slow reaction kinetics of the hydrogen evolution and oxidation reactions (HER/HOR) on platinum in alkaline electrolytes hinders the development of alkaline electrolysers, solar hydrogen cells and alkaline fuel cells. A fundamental understanding of the exchange current density of the HER/HOR in alkaline media is critical for the search and design of highly active electrocatalysts. By studying the HER on a series of monometallic surfaces, we demonstrate that the HER exchange current density in alkaline solutions can be correlated with the calculated hydrogen binding energy (HBE) on the metal surfaces via a volcano type of relationship. The HER activity varies by several orders of magnitude from Pt at the peak of the plot to W and Au located on the bottom of each side of the plot, similar to the observation in acids. Such a correlation suggests that the HBE can be used as a descriptor for identifying electrocatalysts for HER/HOR in alkaline media, and that the HER exchange current density can be tuned by modifying the surface chemical properties.
Michel, Kathryn E; Anderson, Wendy; Cupp, Carolyn; Laflamme, Dorothy P
2011-10-01
Body condition scoring (BCS) systems primarily assess body fat. Both overweight and underweight animals may have loss of lean tissue that may not be noted using standard BCS systems. Catabolism of lean tissue can occur rapidly, may account for a disproportionate amount of body mass loss in sick cats and can have deleterious consequences for outcome. Therefore, along with evaluation of body fat, patients should undergo evaluation of muscle mass. The aims of the present study were first to evaluate the repeatability and reproducibility of a 4-point feline muscle mass scoring (MMS) system and second to assess the convergent validity of MMS by dual-energy X-ray absorptiometry (DXA). MMS was as follows: 3, normal muscle mass; 2, slight wasting; 1, moderate wasting; 0, severe wasting. For the first aim, forty-four cats were selected for evaluation based on age and BCS, and for the second aim, thirty-three cats were selected based on age, BCS and MMS. Cats were scored by ten different evaluators on three separate occasions. Body composition was determined by DXA. Inter- and intra-rater agreement were assessed using kappa analysis. Correlation between MMS and BCS, age, percentage lean body mass and lean body mass (LBM) was determined using Spearman's rank-order correlation. The MMS showed moderate inter-rater agreement in cats that scored normal or severely wasted (κ = 0.48-0.53). Intra-rater agreement was substantial (κ = 0.71-0.73). The MMS was significantly correlated with BCS (r 0.76, P < 0.0001), age (r - 0.75, P < 0.0001), LBM (g) (r 0.62, P < 0.0001) and percentage LBM (r - 0.49, P < 0.0035). Additional investigation is needed to determine whether the MMS can be refined and to assess its clinical applicability.
Energy selection is not correlated in the Qx and Qy bands of a Mg-porphyrin embedded in a protein.
Suisalu, A; Mauring, K; Kikas, J; Herenyi, L; Fidy, J
2001-01-01
The Qx-Qy splitting observed in the fluorescence excitation spectra of Mg-mesoporphyrin-IX substituted horseradish peroxidase (MgMP-HRP) and of its complex with naphthohydroxamic acid (NHA) was studied by spectral hole burning techniques. The width of a hole directly burnt in the Qy band and that of a satellite hole indirectly produced in Qy as a result of hole burning in Qx was compared. We also studied the dependence of the satellite hole in the Qy band on the burning frequency used in the Qx band. Both the directly and indirectly burnt holes were very broad in the (higher energy) Qy band. The width of the satellite hole in the Qy band was equal to the entire width of the inhomogeneously broadened band, independently from the position of hole burning in Qx. This is indicative of a clear lack of correlation between the electronic transition energies of the Qx and Qy bands. A photoproduct was produced by laser irradiation of the MgMP-HRP/NHA complex and was identified as a species with lowered Q-splitting. Conversion of the photoproduct could be achieved by thermal activation measured in temperature-cycling experiments, with a characteristic temperature of 25 K. We attribute the phototransformation to a conformational change of MgMP. PMID:11159420
Fu, Liangliang; Xu, Yueyuan; Hou, Ye; Qi, Xiaolong; Zhou, Lian; Liu, Huiying; Luan, Yu; Jing, Lu; Miao, Yuanxin; Zhao, Shuhong; Liu, Huazhen; Li, Xinyun
2017-03-27
Feed efficiency (FE) is a highly important economic trait in pig production. Investigating the molecular mechanisms of FE is essential for trait improvement. In this study, the skeletal muscle proteome of high-FE and low-FE pigs were investigated by the iTRAQ approach. A total of 1780 proteins were identified, among which 124 proteins were differentially expressed between the high- and low-FE pigs, with 74 up-regulated and 50 down-regulated in the high-FE pigs. Ten randomly selected differentially expressed proteins (DEPs) were validated by Western blotting and quantitative PCR (qPCR). Gene ontology (GO) analysis showed that all the 25 DEPs located in mitochondria were down-regulated in the high-FE pigs. Furthermore, the glucose-pyruvate-tricarboxylic acid (TCA)-oxidative phosphorylation energy metabolism signaling pathway was found to differ between high- and low-FE pigs. The key enzymes involved in the conversion of glucose to pyruvate were up-regulated in the high-FE pigs. Thus, our results suggested mitochondrial energy metabolism in the skeletal muscle tissue was negatively correlated with FE in pigs, and glucose utilization to generate ATP was more efficient in the skeletal muscle tissue of high-FE pigs. This study offered new targets and pathways for improvement of FE in pigs.
Kovalenko, V. N.; Vechernin, V. V.
2016-01-22
The ultrarelativistic collisions of heavy and light ions in the center-of-mass energy range from a few up to a hundred GeV per nucleon have been considered in string fusion approach. A Monte Carlo model of proton-proton, proton-nucleus, and nucleus-nucleus collisions has been developed, which takes into account both the string fusion and the finite rapidity length of strings, implementing the hadronic scattering through the interaction of color dipoles. It well describes the proton-nucleus and nucleus-nucleus collisions at the partonic level without using Glauber model of nuclear collisions. All parameters are fixed using experimental data on inelastic cross section and multiplicity. In the framework of the model, we performed a beam energy and system size scan and studied the behaviour of n-n, pt-n and pt-pt long-range correlation coefficients. The detailed modeling of the event by event charged particles production allowed to provide predictions in the conditions close to the experimental ones allowing a direct comparison to the data.
Fu, Liangliang; Xu, Yueyuan; Hou, Ye; Qi, Xiaolong; Zhou, Lian; Liu, Huiying; Luan, Yu; Jing, Lu; Miao, Yuanxin; Zhao, Shuhong; Liu, Huazhen; Li, Xinyun
2017-01-01
Feed efficiency (FE) is a highly important economic trait in pig production. Investigating the molecular mechanisms of FE is essential for trait improvement. In this study, the skeletal muscle proteome of high-FE and low-FE pigs were investigated by the iTRAQ approach. A total of 1780 proteins were identified, among which 124 proteins were differentially expressed between the high- and low-FE pigs, with 74 up-regulated and 50 down-regulated in the high-FE pigs. Ten randomly selected differentially expressed proteins (DEPs) were validated by Western blotting and quantitative PCR (qPCR). Gene ontology (GO) analysis showed that all the 25 DEPs located in mitochondria were down-regulated in the high-FE pigs. Furthermore, the glucose-pyruvate-tricarboxylic acid (TCA)-oxidative phosphorylation energy metabolism signaling pathway was found to differ between high- and low-FE pigs. The key enzymes involved in the conversion of glucose to pyruvate were up-regulated in the high-FE pigs. Thus, our results suggested mitochondrial energy metabolism in the skeletal muscle tissue was negatively correlated with FE in pigs, and glucose utilization to generate ATP was more efficient in the skeletal muscle tissue of high-FE pigs. This study offered new targets and pathways for improvement of FE in pigs. PMID:28345649
NASA Astrophysics Data System (ADS)
Werth, S. P.; Frasier, S. J.
2015-12-01
Wind energy is one of the fastest-growing segments of the world energy market, offering a clean and abundant source of electricity. However, wind energy facilities can have detrimental effects on wildlife, especially birds and bats. Monitoring systems based on marine navigation radar are often used to quantify migration near potential wind sites, but the ability to reliably distinguish between bats and different varieties of birds has not been practically achieved. This classification capability would enable wind site selection that protects more vulnerable species, such as bats and raptors. Flight behavior, such as wing beat frequency, changes in speed, or changes in orientation, are known to vary by species [1]. The ability to extract these properties from radar data could ultimately enable a species based classification scheme. In this work, we analyze the relationship between radar measurements and bird flight behavior in echoes from avifauna. During the 2014 fall migration season, the UMass dual polarized weather radar was used to collect low elevation observations of migrating birds as they traversed through a fixed antenna beam. The radar was run during the night time, in clear-air conditions. Data was coherently integrated, and detections of biological targets exceeding an SNR threshold were extracted. Detections without some dominant frequency content (i.e. clear periodicity, potentially the wing beat frequency) were removed from the sample in order to isolate observations suspected to contain a single species or bird. For the remaining detections, measurements including the polarimetric products and the Doppler spectrum were extracted at each time step over the duration of the observation. The periodic and time changing nature of some of these different measurements was found to have a strong correlation with flight behavior (i.e. flapping vs. gliding behavior). Assumptions about flight behavior and orientation were corroborated through scattering
Bel-Serrat, Silvia; Julián-Almárcegui, Cristina; González-Gross, Marcela; Mouratidou, Theodora; Börnhorst, Claudia; Grammatikaki, Evangelia; Kersting, Mathilde; Cuenca-García, Magdalena; Gottrand, Frederic; Molnár, Dénes; Hallström, Lena; Dallongeville, Jean; Plada, Maria; Roccaldo, Romana; Widhalm, Kurt; Moreno, Luis A; Manios, Yannis; De Henauw, Stefaan; Leclercq, Catherine; Vandevijvere, Stefanie; Lioret, Sandrine; Gutin, Bernard; Huybrechts, Inge
2016-04-01
This study examined the correlates of dietary energy under-reporting (UR) and over-reporting (OV) in European adolescents. Two self-administered computerised 24-h dietary recalls and physical activity data using accelerometry were collected from 1512 adolescents aged 12·5-17·5 years from eight European countries. Objective measurements of height and weight were obtained. BMI was categorised according to Cole/International Obesity Task Force (IOTF) cut-off points. Diet-related attitudes were assessed via self-administered questionnaires. Reported energy intake (EI) was compared with predicted total energy expenditure to identify UR and OV using individual physical activity objective measures. Associations between misreporting and covariates were examined by multilevel logistic regression analyses. Among all, 33·3 % of the adolescents were UR and 15·6 % were OV when considering mean EI. Overweight (OR 3·25; 95 % CI 2·01, 5·27) and obese (OR 4·31; 95 % CI 1·92, 9·65) adolescents had higher odds for UR, whereas underweight individuals were more likely to over-report (OR 1·67; 95 % CI 1·01, 2·76). Being content with their own figures (OR 0·61; 95 % CI 0·41, 0·89) decreased the odds for UR, whereas frequently skipping breakfast (OR 2·14; 95 % CI 1·53, 2·99) was linked with higher odds for UR. Those being worried about gaining weight (OR 0·55; 95 % CI 0·33, 0·92) were less likely to OV. Weight status and psychosocial weight-related factors were found to be the major correlates of misreporting. Misreporting may reflect socially desirable answers and low ability to report own dietary intakes, but also may reflect real under-eating in an attempt to lose weight or real over-eating to reflect higher intakes due to growth spurts. Factors influencing misreporting should be identified in youths to clarify or better understand diet-disease associations.
Correlating low-energy electron microscopy and micro-Raman imaging of epitaxial graphene on SiC
NASA Astrophysics Data System (ADS)
Cheng, Guangjun; Calizo, Irene; Meade, Patrick; He, Guowei; Real, M. A.; Elmquist, R. E.; Feenstra, R. M.; Hight Walker, A. R.
2013-03-01
Several techniques exist for determining the number of graphene layers grown on SiC such as low-energy electron microscopy (LEEM) and Raman spectroscopy. The method which is arguably the most definitive for SiC-grown graphene isLEEM. Low-energy (0 - 10 eV) electrons interfere with the graphene layers, yielding minima in the electron reflectivity vs. energy curve that can be used to determine the layer number.1 LEEM also provides the means of collecting selected-area diffraction on ?m-size surface regions (micro-LEED), giving access to further useful structural information. While Raman spectroscopy is also commonly used to determine graphene layer number on SiC substrates; such measurements have no definitive calibration for large-area graphene on SiC, unlike the case of exfoliated graphene on SiO2. In this talk, results of correlated LEEM/micro-Raman imaging of large-area, mono and multilayer graphene samples are presented. These initial findings show that LEEM can show the contrast between terrace regions and step edges at particular areas of monolayer-graphene surfaces. Micro-Raman imaging of these same locations show Raman shifts in the G' (2D) band. The influence of heterogeneities on electrical behavior of graphene will be discussed. Comparative studies of multilayer graphene are in progress, and will also be reported. 1. H. Hibino, et al., Phys. Rev. B 77, 075413 (2008). 2. L. I. Johansson, et al., Phys. Rev. B 84, 125405 (2011).
NASA Technical Reports Server (NTRS)
Dyall, Kenneth G.
1993-01-01
Dirac-Hartree-Fock calculations have been carried out on the ground states of the group IV monoxides GeO, SnO and PbO. Geometries, dipole moments and infrared data are presented. For comparison, nonrelativistic, first-order perturbation and relativistic effective core potential calculations have also been carried out. Where appropriate the results are compared with the experimental data and previous calculations. Spin-orbit effects are of great importance for PbO, where first-order perturbation theory including only the mass-velocity and Darwin terms is inadequate to predict the relativistic corrections to the properties. The relativistic effective core potential results show a larger deviation from the all-electron values than for the hydrides, and confirm the conclusions drawn on the basis of the hydride calculations.
NASA Astrophysics Data System (ADS)
Klüppelberg, Daniel A.; Betzinger, Markus; Blügel, Stefan
2015-01-01
We analyze the accuracy of the atomic force within the all-electron full-potential linearized augmented plane-wave (FLAPW) method using the force formalism of Yu et al. [Phys. Rev. B 43, 6411 (1991), 10.1103/PhysRevB.43.6411]. A refinement of this formalism is presented that explicitly takes into account the tail of high-lying core states leaking out of the muffin-tin sphere and considers the small discontinuities of LAPW wave function, density, and potential at the muffin-tin sphere boundaries. For MgO and EuTiO3 it is demonstrated that these amendments substantially improve the acoustic sum rule and the symmetry of the force constant matrix. Sum rule and symmetry are realized with an accuracy of μ Htr /aB .
NASA Technical Reports Server (NTRS)
Dyall, Kenneth G.
1991-01-01
Dirac-Hartree-Fock calculations have been carried out on the ground states of the group IV monoxides GeO, SnO and PbO. Geometries, dipole moments and infrared data are presented. For comparison, nonrelativistic, first-order perturbation and relativistic effective core potential calculations have also been carried out. Where appropriate the results are compared with the experimental data and previous calculations. Spin-orbit effects are of great importance for PbO, where first-order perturbation theory including only the mass-velocity and Darwin terms is inadequate to predict the relativistic corrections to the properties. The relativistic effective core potential results show a larger deviation from the all-electron values than for the hydrides, and confirm the conclusions drawn on the basis of the hydride calculations.
NASA Astrophysics Data System (ADS)
Sandratskii, L. M.
2015-10-01
We report the first-principles study of the correlated behavior of the magnetic anisotropy energy (MAE) and orbital moment anisotropy (OMA) as the functions of the thickness N of the Fe film. The work is motivated by recent experimental studies combining photoemission, x-ray magnetic circular dichroism, and magnetic anisotropy measurements. In agreement with experiment, the correlated oscillations of MAE (N ) and OMA (N ) are obtained that have their origin in the formation of the 3d quantum well states (QWS) confined in the films. The main contribution to the oscillation amplitude comes from the surface layer. This is an interesting feature of the phenomenon consisting in the peculiar dependence of the physical quantities on the thickness of the film. We demonstrate that the band structure of the bulk Fe does not reflect adequately the properties of the 3d QWS in thin films and, therefore, does not provide the basis for understanding the oscillations of MAE (N ) and OMA (N ) . A detailed point-by-point analysis in the two-dimensional (2D) Brillouin zone (BZ) of the film shows that the contribution of the Γ point, contrary to a rather common expectation, does not play an important role in the formation of the oscillations. Instead, the most important contributions come from a broad region of the 2D BZ distant from the center of the BZ. Combining symmetry arguments and direct calculations we show that orbital moments of the electronic states possess nonzero transverse components orthogonal to the direction of the spin magnetization. The account for this feature is crucial in the point-by-point analysis of the OMA. On the basis of the calculations for noncollinear spin configurations we suggest interpretations of two interesting experimental findings: fast temperature decay of the oscillation amplitude in MAE (N ) and unexpectedly strong spin mixing of the initial states of the photoemission process.
Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Bouvier, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R.; Benbow, W.; Byrum, K.; Cesarini, A.; Connolly, M. P.; Ciupik, L.; Collins-Hughes, E.; Cui, W.; Duke, C.; Dumm, J.; Falcone, A.; Federici, S. E-mail: mccann@kicp.uchicago.edu; and others
2012-12-01
We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays (E {sub {gamma}} > 150 GeV) and giant radio pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15,366 GRPs were recorded during 11.6 hr of simultaneous observations, which were made across four nights in 2008 December and in 2009 November and December. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. In total, eight different time windows with durations ranging from 0.033 ms to 72 s were positioned at three different locations relative to the GRP to search for enhanced gamma-ray emission which lagged, led, or was concurrent with, the GRP event. Furthermore, we performed separate searches on main pulse GRPs and interpulse GRPs and on the most energetic GRPs in our data sample. No significant enhancement of pulsed VHE emission was found in any of the preformed searches. We set upper limits of 5-10 times the average VHE flux of the Crab pulsar on the flux simultaneous with interpulse GRPs on single-rotation-period timescales. On {approx}8 s timescales around interpulse GRPs, we set an upper limit of 2-3 times the average VHE flux. Within the framework of recent models for pulsed VHE emission from the Crab pulsar, the expected VHE-GRP emission correlations are below the derived limits.
NASA Technical Reports Server (NTRS)
Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bouvier, A.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cesarini, A.; Ciupik, L.; Collins-Hughes, E.; Connolly, M. P.; Cui, W.; Dickherber, R.; Duke, C.; Dumm, J.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Finnegan, G.; Fortson, L.; Perkins, J. S.
2012-01-01
We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays ( E(sub Gamma) > 150 GeV) and giant radio pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15,366 GRPs were recorded during 11.6 hr of simultaneous observations, which were made across four nights in 2008 December and in 2009 November and December. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. In total, eight different time windows with durations ranging from 0.033 ms to 72 s were positioned at three different locations relative to the GRP to search for enhanced gamma-ray emission which lagged, led, or was concurrent with, the GRP event. Furthermore, we performed separate searches on main pulse GRPs and interpulse GRPs and on the most energetic GRPs in our data sample. No significant enhancement of pulsed VHE emission was found in any of the preformed searches. We set upper limits of 5-10 times the average VHE flux of the Crab pulsar on the flux simultaneous with interpulse GRPs on single-rotation-period timescales. On approx. 8 s timescales around interpulse GRPs, we set an upper limit of 2-3 times the average VHE flux. Within the framework of recent models for pulsed VHE emission from the Crab pulsar, the expected VHE-GRP emission correlations are below the derived limits.
Kepp, Kasper P
2011-10-01
Porphyrins are much studied due to their biochemical relevance and many applications. The density functional TPSSh has previously accurately described the energy of close-lying electronic states of transition metal systems such as porphyrins. However, a recent study questioned this conclusion based on calculations of five iron(III) porphines. Here, we compute the geometries of 80 different electronic configurations and the free energies of the most stable configurations with the functionals TPSSh, TPSS, and B3LYP. Zero-point energies and entropy favor high-spin by ~4kJ/mol and 0-10kJ/mol, respectively. When these effects are included, and all electronic configurations are evaluated, TPSSh correctly predicts the spin of all the four difficult phenylporphine cases and is within the lower bound of uncertainty of any known theoretical method for the fifth, iron(III) chloroporphine. Dispersion computed with DFT-D3 favors low-spin by 3-53kJ/mol (TPSSh) or 4-15kJ/mol (B3LYP) due to the attractive r(-6) term and the shorter distances in low-spin. The very large and diverse corrections from TPSS and TPSSh seem less consistent with the similarity of the systems than when calculated from B3LYP. If the functional-specific corrections are used, B3LYP and TPSSh are of equal accuracy, and TPSS is much worse, whereas if the physically reasonable B3LYP-computed dispersion effect is used for all functionals, TPSSh is accurate for all systems. B3LYP is significantly more accurate when dispersion is added, confirming previous results.
Johnson, Barry C.; Métifiot, Mathieu; Pommier, Yves
2012-01-01
The design of novel integrase (IN) inhibitors has been aided by recent crystal structures revealing the binding mode of these compounds with a full-length prototype foamy virus (PFV) IN and synthetic viral DNA ends. Earlier docking studies relied on incomplete structures and did not include the contribution of the viral DNA to inhibitor binding. Using the structure of PFV IN as the starting point, we generated a model of the corresponding HIV-1 complex and developed a molecular dynamics (MD)-based approach that correlates with the in vitro activities of novel compounds. Four well-characterized compounds (raltegravir, elvitegravir, MK-0536, and dolutegravir) were used as a training set, and the data for their in vitro activity against the Y143R, N155H, and G140S/Q148H mutants were used in addition to the wild-type (WT) IN data. Three additional compounds were docked into the IN-DNA complex model and subjected to MD simulations. All three gave interaction potentials within 1 standard deviation of values estimated from the training set, and the most active compound was identified. Additional MD analysis of the raltegravir- and dolutegravir-bound complexes gave internal and interaction energy values that closely match the experimental binding energy of a compound related to raltegravir that has similar activity. These approaches can be used to gain a deeper understanding of the interactions of the inhibitors with the HIV-1 intasome and to identify promising scaffolds for novel integrase inhibitors, in particular, compounds that retain activity against a range of drug-resistant mutants, making it possible to streamline synthesis and testing. PMID:22037850
NASA Astrophysics Data System (ADS)
Duguet, T.; Bender, M.; Ebran, J.-P.; Lesinski, T.; Somà, V.
2015-12-01
This programmatic paper lays down the possibility to reconcile the necessity to resum many-body correlations into the energy kernel with the fact that safe multi-reference energy density functional (EDF) calculations cannot be achieved whenever the Pauli principle is not enforced, as is for example the case when many-body correlations are parametrized under the form of empirical density dependencies. Our proposal is to exploit a newly developed ab initio many-body formalism to guide the construction of safe, explicitly correlated and systematically improvable parametrizations of the off-diagonal energy and norm kernels that lie at the heart of the nuclear EDF method. The many-body formalism of interest relies on the concepts of symmetry breaking and restoration that have made the fortune of the nuclear EDF method and is, as such, amenable to this guidance. After elaborating on our proposal, we briefly outline the project we plan to execute in the years to come.
NASA Astrophysics Data System (ADS)
Pervukhina, Marina; Kuwahara, Yasuto
2008-01-01
Electrical conductivity and seismic velocity are studied for plausible pore geometries in the Earth's interior for reliable quantitative analysis of experimental data such as seismic tomography and magnetotelluric explorations. Electrical conductivity of a two-phase system with equilibrium, interfacial energy-controlled phase geometry is calculated for the dihedral angles θ = 40°-100° that are typical for rock-aqueous fluid and θ = 20°-60° for rock-melt systems of lower crust and upper mantle for the case of tetrakaidecahedral grains. Electrical conductivity vs. seismic velocity correlations are acquired by combining of the simulated electrical conductivities with the seismic velocity calculated with the help of equilibrium geometry model Takei [Takei, Y., Effect of pore geometry on VP/ VS: From equilibrium geometry to crack. J. Geophys. Res. 107 (2002): 10.1029/2001JB000522.] for the same pore geometries. The results show that electrical conductivity gradually decreases reaching zero when seismic velocities reach seismic velocities of intact rock for rock-melt systems, while for rock-aqueous fluid systems with θ ≥ 60° conductivity drops to zero at velocities up to 10% smaller. This can explain the seeming discrepancy of the low seismic velocity region, attributed to the high fluid fraction, and the low electrical conductivity of the same region, which is sometimes faced at collocated electromagnetic and seismic experiments.
NASA Astrophysics Data System (ADS)
Chu, Iek-Heng; Trinastic, Jonathan P.; Wang, Yun-Peng; Eguiluz, Adolfo G.; Kozhevnikov, Anton; Schulthess, Thomas C.; Cheng, Hai-Ping
2016-03-01
The G W approximation is a well-known method to improve electronic structure predictions calculated within density functional theory. In this work, we have implemented a computationally efficient G W approach that calculates central properties within the Matsubara-time domain using the modified version of elk, the full-potential linearized augmented plane wave (FP-LAPW) package. Continuous-pole expansion (CPE), a recently proposed analytic continuation method, has been incorporated and compared to the widely used Padé approximation. Full crystal symmetry has been employed for computational speedup. We have applied our approach to 18 well-studied semiconductors/insulators that cover a wide range of band gaps computed at the levels of single-shot G0W0 , partially self-consistent G W0 , and fully self-consistent G W (full-G W ), in conjunction with the diagonal approximation. Our calculations show that G0W0 leads to band gaps that agree well with experiment for the case of simple s -p electron systems, whereas full-G W is required for improving the band gaps in 3 d electron systems. In addition, G W0 almost always predicts larger band gap values compared to full-G W , likely due to the substantial underestimation of screening effects as well as the diagonal approximation. Both the CPE method and Padé approximation lead to similar band gaps for most systems except strontium titantate, suggesting that further investigation into the latter approximation is necessary for strongly correlated systems. Moreover, the calculated cation d band energies suggest that both full-G W and G W0 lead to results in good agreement with experiment. Our computed band gaps serve as important benchmarks for the accuracy of the Matsubara-time G W approach.
Cho, Chul-Woong; Yun, Yeoung-Sang
2016-06-01
In silico prediction model for toxicological effects of ionic liquids (ILs) is useful to understand ILs' toxicological interactions and to design environmentally benign IL structures. Actually, it is essential since the types of ILs are extremely numerous. Accordingly, prediction models were developed in this study. For the modelling, well-defined linear free energy relationship (LFER) descriptors - i.e. excess molar refraction (E), dipolarity/polarizability (S), H-bonding acidity (A), H-bonding basicity (B), McGowan volume (V), cation interaction (J(+)) and anion interaction (J(-)) - were in silico calculated using density functional theory and conductor-like screening model. These descriptors were then correlated with the toxicological values of ILs to Daphnia magna. First, a model established by Hoover et al. (2007) using measured LFER descriptors of 97 neutral compounds was applied to the prediction of ILs' toxicity. As expected, the model by Hoover et al. (2007) needs to be amended for ILs. To that end, the difference in toxicological interactions between neutral compounds and ILs was addressed by additional single J(+) or five LFER descriptors of cation i.e. Ec, Sc, Bc, Vc, and J(+). Secondly, a prediction model for only ILs was developed by using the three LFER descriptors Ec, Bc, and J(+). The model had a reasonable predictability and robustness of R(2) = 0.880 for the training set, 0.848 for the test set, and 0.867 for the overall set. The established models can be used to design environmentally benign IL structures and to reduce labour, danger, time, and materials compared to the experiment-based study.
ERIC Educational Resources Information Center
Online-Offline, 1998
1998-01-01
This issue focuses on the theme of "Energy," and describes several educational resources (Web sites, CD-ROMs and software, videos, books, activities, and other resources). Sidebars offer features on alternative energy, animal energy, internal combustion engines, and energy from food. Subthemes include harnessing energy, human energy, and…
NASA Astrophysics Data System (ADS)
Abu-Zayyad, T.; Aida, R.; Allen, M.; Anderson, R.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, E. J.; Cho, W. R.; Fujii, H.; Fujii, T.; Fukuda, T.; Fukushima, M.; Hanlon, W.; Hayashi, K.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Hiyama, K.; Honda, K.; Iguchi, T.; Ikeda, D.; Ikuta, K.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Iwamoto, S.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kanbe, T.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, H. K.; Kim, J. H.; Kim, J. H.; Kitamoto, K.; Kitamura, S.; Kitamura, Y.; Kobayashi, K.; Kobayashi, Y.; Kondo, Y.; Kuramoto, K.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lim, S. I.; Lundquist, J. P.; Machida, S.; Martens, K.; Matsuda, T.; Matsuura, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Miyata, K.; Murano, Y.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nam, S. W.; Nonaka, T.; Ogio, S.; Ohnishi, M.; Ohoka, H.; Oki, K.; Oku, D.; Okuda, T.; Ono, M.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Roh, S. Y.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Sampson, A. L.; Scott, L. M.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Shin, J. I.; Shirahama, T.; Smith, J. D.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T.; Suzuki, S.; Takahashi, Y.; Takeda, M.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Tsuyuguchi, Y.; Uchihori, Y.; Udo, S.; Ukai, H.; Urban, F.; Vasiloff, G.; Wada, Y.; Wong, T.; Yamakawa, Y.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zhou, X.; Zollinger, R.; Zundel, Z.
2013-11-01
We search for correlations between the positions of extragalactic objects and the arrival directions of ultra-high energy cosmic rays (UHECRs) with primary energy E >= 40 EeV as observed by the surface detector array of the Telescope Array (TA) experiment during the first 40 months of operation. We examine several public astronomical object catalogs, including the Veron-Cetty and Veron catalog of active galactic nuclei. We count the number of TA events correlated with objects in each catalog as a function of three parameters: the maximum angular separation between a TA event and an object, the minimum energy of the events, and the maximum redshift of the objects. We determine the combination of these parameters that maximizes the correlations, and we calculate the probability of having the same levels of correlations from an isotropic distribution of UHECR arrival directions. No statistically significant correlations are found when penalties for scanning over the above parameters and for searching in several catalogs are taken into account.
TiCl, TiH and TiH+ Bond Energies, a Test of a Correlation Consistent Ti Basis Set
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)
1999-01-01
Correlation consistent basis sets are developed for Ti atom. The polarization functions are optimized for the average of the 3F and 5F states. One series of correlation consistent basis sets is for 3d and 4s correlation, while the second series includes 3s and 3p correlation as well as 3d and 4s correlation. These basis sets are tested using the Ti 3F-5F separation and the dissociation energies of TiCl X4Phi, TiH X4Phi, and TiH(+) X3Phi. The CCSD(T) complete basis set limit values are determined by extrapolation. The Douglas Kroll approach is used to compute the scalar relativistic effect. Spin-orbit effects are taken from experiment and/or computed at the CASSCF level. The Ti 3F-5F separation is in excellent agreement with experiment, while the TiCl, TiH, and TiH(+) bond energies are in good agreement with experiment. Extrapolation with the valence basis set is consistent with other atoms, while including 3s and 3p correlation appears to make extrapolation.
Li, Y Q; Varandas, A J C
2010-09-16
An accurate single-sheeted double many-body expansion potential energy surface is reported for the title system which is suitable for dynamics and kinetics studies of the reactions of N(2D) + H2(X1Sigmag+) NH(a1Delta) + H(2S) and their isotopomeric variants. It is obtained by fitting ab initio energies calculated at the multireference configuration interaction level with the aug-cc-pVQZ basis set, after slightly correcting semiempirically the dynamical correlation using the double many-body expansion-scaled external correlation method. The function so obtained is compared in detail with a potential energy surface of the same family obtained by extrapolating the calculated raw energies to the complete basis set limit. The topographical features of the novel global potential energy surface are examined in detail and found to be in general good agreement with those calculated directly from the raw ab initio energies, as well as previous calculations available in the literature. The novel function has been built so as to become degenerate at linear geometries with the ground-state potential energy surface of A'' symmetry reported by our group, where both form a Renner-Teller pair.
Rocca, Dario
2014-05-14
A new ab initio approach is introduced to compute the correlation energy within the adiabatic connection fluctuation dissipation theorem in the random phase approximation. First, an optimally small basis set to represent the response functions is obtained by diagonalizing an approximate dielectric matrix containing the kinetic energy contribution only. Then, the Lanczos algorithm is used to compute the full dynamical dielectric matrix and the correlation energy. The convergence issues with respect to the number of empty states or the dimension of the basis set are avoided and the dynamical effects are easily kept into account. To demonstrate the accuracy and efficiency of this approach the binding curves for three different configurations of the benzene dimer are computed: T-shaped, sandwich, and slipped parallel.
Mizutani, U; Inukai, M; Sato, H; Zijlstra, E S; Lin, Q
2014-05-16
There are three key electronic parameters in elucidating the physics behind the Hume–Rothery electron concentration rule: the square of the Fermi diameter (2kF)2, the square of the critical reciprocal lattice vector and the electron concentration parameter or the number of itinerant electrons per atom e/a. We have reliably determined these three parameters for 10 Rhombic Triacontahedron-type 2/1–2/1–2/1 (N = 680) and 1/1–1/1–1/1 (N = 160–162) approximants by making full use of the full-potential linearized augmented plane wave-Fourier band calculations based on all-electron density-functional theory. We revealed that the 2/1–2/1–2/1 approximants Al13Mg27Zn45 and Na27Au27Ga31 belong to two different sub-groups classified in terms of equal to 126 and 109 and could explain why they take different e/a values of 2.13 and 1.76, respectively. Among eight 1/1–1/1–1/1 approximants Al3Mg4Zn3, Al9Mg8Ag3, Al21Li13Cu6, Ga21Li13Cu6, Na26Au24Ga30, Na26Au37Ge18, Na26Au37Sn18 and Na26Cd40Pb6, the first two, the second two and the last four compounds were classified into three sub-groups with = 50, 46 and 42; and were claimed to obey the e/a = 2.30, 2.10–2.15 and 1.70–1.80 rules, respectively.
NASA Astrophysics Data System (ADS)
Mizutani, U.; Inukai, M.; Sato, H.; Zijlstra, E. S.; Lin, Q.
2014-08-01
There are three key electronic parameters in elucidating the physics behind the Hume-Rothery electron concentration rule: the square of the Fermi diameter (2kF)2, the square of the critical reciprocal lattice vector ? and the electron concentration parameter or the number of itinerant electrons per atom e/a. We have reliably determined these three parameters for 10 Rhombic Triacontahedron-type 2/1-2/1-2/1 (N = 680) and 1/1-1/1-1/1 (N = 160-162) approximants by making full use of the full-potential linearized augmented plane wave-Fourier band calculations based on all-electron density-functional theory. We revealed that the 2/1-2/1-2/1 approximants Al13Mg27Zn45 and Na27Au27Ga31 belong to two different sub-groups classified in terms of ? equal to 126 and 109 and could explain why they take different e/a values of 2.13 and 1.76, respectively. Among eight 1/1-1/1-1/1 approximants Al3Mg4Zn3, Al9Mg8Ag3, Al21Li13Cu6, Ga21Li13Cu6, Na26Au24Ga30, Na26Au37Ge18, Na26Au37Sn18 and Na26Cd40Pb6, the first two, the second two and the last four compounds were classified into three sub-groups with ? = 50, 46 and 42; and were claimed to obey the e/a = 2.30, 2.10-2.15 and 1.70-1.80 rules, respectively.
NASA Astrophysics Data System (ADS)
Ibragimov, Ranis N.
2016-12-01
The nonlinear Euler equations are used to model two-dimensional atmosphere dynamics in a thin rotating spherical shell. The energy balance is deduced on the basis of two classes of functorially independent invariant solutions associated with the model. It it shown that the energy balance is exactly the conservation law for one class of the solutions whereas the second class of invariant solutions provides and asymptotic convergence of the energy balance to the conservation law.
NASA Astrophysics Data System (ADS)
Shabbir, A.; Verdoolaege, G.; Hornung, G.; Kardaun, O. J. W. F.; Zohm, H.; Contributors, JET
2017-03-01
Several important ELM control techniques are in large part motivated by the empirically observed inverse relationship between average ELM energy loss and ELM frequency in a plasma. However, to ensure a reliable effect on the energy released by the ELMs, it is important that this relation is verified for individual ELM events. Therefore, in this work the relation between ELM energy loss ≤ft({{W}\\text{ELM}}\\right) and waiting time ≤ft(Δ {{t}\\text{ELM}}\\right) is investigated for individual ELMs in a set of ITER-like wall plasmas in JET. A comparison is made with the results from a set of carbon-wall and nitrogen-seeded ITER-like wall JET plasmas. It is found that the correlation between W ELM and Δ {{t}\\text{ELM}} for individual ELMs varies from strongly positive to zero. Furthermore, the effect of the extended collapse phase often accompanying ELMs from unseeded JET ILW plasmas and referred to as the slow transport event (STE) is studied on the distribution of ELM durations, and on the correlation between W ELM and Δ {{t}\\text{ELM}} . A high correlation between W ELM and Δ {{t}\\text{ELM}} , comparable to CW plasmas is only found in nitrogen-seeded ILW plasmas. Finally, a regression analysis is performed using plasma engineering parameters as predictors for determining the region of the plasma operational space with a high correlation between W ELM and Δ {{t}\\text{ELM}} .
NASA Technical Reports Server (NTRS)
Akasofu, S.-I.
1979-01-01
Akasofu (1979) has reported that the interplanetary parameter epsilon correlates reasonably well with the magnetospheric substorm index AE; in the first approximation, epsilon represents the solar wind coupled to the magnetosphere. The correlation between the interplanetary parameter, the auroral electrojet index and the ring current index is examined for three magnetic storms. It is shown that when the interplanetary parameter exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, producing an abnormal growth of the ring current index.
NASA Technical Reports Server (NTRS)
Den Hartog, G.; Neumann, H. H.; King, K. M.; Chipanshi, A. C.
1994-01-01
Fluxes of heat and water vapor were measured on a 20-m tower at Kinosheo Lake in the Hudson Bay lowlands using eddy correlation and Bowen ratio energy balance techniques. The study period was June 25 to July 28, 1990. Measurements were made over a peat bog consisting of a mixture of sphagnum moss and lichen hummocks and black pools. About 200 m west of the tower were several shallow ponds. The hummocks had a dry, insulating surface and were underlain by an ice layer near 50 cm depth until mid-July. At the beginning of the period the black pools were covered with water, and although the free water gradually disappeared over the study period, they remained saturated to the end of July. The depth of peat near the tower was about 3 m. Despite the ice layer under the hummocks, their daytime surface temperatures were high, near 35 C, and after the middle of July, above 40 C. Inspection of temperature, precipitation, and radiation data showed that the midsummer period of 1990 was warmer, drier, and sunnier than usual at Moosonee and so by influence at Lake Kinosheo. When all the data were combined to yield average diurnal energy balance components, the eddy correlation fluxes accounted for 90% of the available energy. Latent heat flux averaged 46% of the total available energy and the sensible heat flux averaged 34%. Daytime Bowen ratios were near 1 for the experimental period, suggesting that the bog behaved more like a dryland than a wetland. Eddy correlation measurements of sensible heat and latent heat flux were less than those measured using the Bowen ratio energy balance technique, the average ratios being 0.81 and 0.86 respectively. These differences were possibly due to the difficulty in measuring energy balance components of net radiation and ground heat flux over the mosaic surface.
NASA Astrophysics Data System (ADS)
Pais, H.; Sulaksono, A.; Agrawal, B. K.; Providência, C.
2016-04-01
The correlations of the crust-core transition density and pressure in neutron stars with the slope of the symmetry energy and the neutron skin thickness are investigated, using different families of relativistic mean-field parametrizations with constant couplings and nonlinear terms mixing the σ - , ω - , and ρ -meson fields. It is shown that the modification of the density dependence of the symmetry energy, involving the σ or the ω meson, gives rise to different behaviors: the effect of the ω meson may also be reproduced within nonrelativistic phenomenological models, while the effect of the σ meson is essentially relativistic. Depending on the parametrization with σ -ρ or ω -ρ mixing terms, different values of the slope of the symmetry energy at saturation must be considered in order to obtain a neutron matter equation of state compatible with results from chiral effective field theory. This difference leads to different pressures at the crust-core transition density. A linear correlation between the transition density and the symmetry energy slope or the neutron skin thickness of the 208Pb nucleus is obtained, only when the ω meson is used to describe the density dependence of the symmetry energy. A comparison is made between the crust-core transition properties of neutron stars obtained by three different methods, the relativistic random phase approximation (RRPA), the Vlasov equation, and thermodynamical method. It is shown that the RRPA and the Vlasov methods predict similar transition densities for p n e β -equilibrium stellar matter.
NASA Astrophysics Data System (ADS)
Dadykin, V. L.; Khalchukov, F. F.; Korchagin, P. V.; Korolkova, E. V.; Kudryavtsev, V. A.; Mal'Gin, A. S.; Ryasny, V. G.; Ryazhskaya, O. G.; Yakushev, V. F.; Zatsepin, G. T.; Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.; Fulgione, W.; Galeotti, P.; Saavedra, O.; Trinchero, G.; Vernetto, S.
The authors have analysed the data of LSD from February 10, 1987, to March 7, 1987, in order to search for autocorrelations between all pulses detected by LSD with energy higher than 5 MeV like those that occurred at ≡3:00 UT on February 23, 1987, between the pulses detected by three neutrino telescopes and two gravitational wave antennae. The authors have found 9 pairs of correlated pulses (muon + low energy pulse) from 5:42 UT to 10:13 UT on February 23, 1987.
Ou, Iwa; Yamada, Yoshiyuki; Yano, Takatomi; Mori, Takaaki; Kayano, Tsubasa; Sakuda, Makoto; Kimura, Atsushi; Harada, Hideo
2014-05-02
We conducted an experiment using the JPARC-ANNRI spectrometer to measure the energy, multiplicity and correlation of γ-rays from the neutron capture of natural gadolinium. We incorporated the GEANT4 Monte Carlo (MC) simulation into the detector, and compared the data with the results of the MC simulation. We report our data analysis and compare our data with those obtained by the MC simulation.
Jing, Linhong; Nash, John J.
2009-01-01
The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer (FT – ICR). Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropanol, were measured for twenty-three structurally different, positively-charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for three of the aryl radicals with isopropanol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of several different hydrogen-atom donors with a few selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X – H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of twenty-nine different aryl radicals and eighteen different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state as the energy difference between the neutral and ionic reactants decreases. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be “tuned” by structural changes that influence either
NASA Astrophysics Data System (ADS)
Huang, Shengzhi; Huang, Qiang; Leng, Guoyong; Zhao, Menglong; Meng, Erhao
2017-03-01
It is of importance to investigate watershed water-energy balance variations and to explore their correlations with vegetation and soil moisture dynamics, which helps better understand the interplays between underlying surface dynamics and the terrestrial water cycle. The heuristic segmentation method was adopted to identify change points in the parameter ω series in Fu's equation belonging to the Budyko framework in the Wei River Basin (WRB) and its sub-basins aiming to examine the validity of stationary assumptions. Additionally, the cross wavelet analysis was applied to explore the correlations between vegetation and soil moisture dynamics and ω variations. Results indicated that (1) the ω variations in the WRB are significant, with some change points identified except for the sub-basin above Zhangjiashan, implying that the stationarity of ω series in the WRB is invalid except for the sub-basin above Zhangjiashan; (2) the correlations between soil moisture series and ω series are weaker than those between Normalized Difference Vegetation Index (NDVI) series and ω series; (3) vegetation dynamics show significantly negative correlations with ω variations in 1983-2003 with a 4-8 year signal in the whole WRB, and both vegetation and soil moisture dynamics exert strong impacts on the parameter ω changes. This study helps understanding the interactions between underlying land surface dynamics and watershed water-energy balance.
NASA Astrophysics Data System (ADS)
Vysotskii, V. I.; Vysotskyy, M. V.
2014-04-01
The features of the formation of correlated coherent states of a particle in a parabolic potential well at its monotonic deformation (expansion or compression) in finite limits have been considered in the presence of dissipation and a stochastic force. It has been shown that, in both deformation regimes, a correlated coherent state is rapidly formed with a large correlation coefficient | r| → 1, which corresponds at a low energy of the particle to a very significant (by a factor of 1050-10100 or larger) increase in the transparency of the potential barrier at its interaction with atoms (nuclei) forming the "walls" of the potential well or other atoms located in the same well. The efficiency of the formation of correlated coherent states, as well as | r|, increases with an increase in the deformation interval and with a decrease in the deformation time. The presence of the stochastic force acting on the particle can significantly reduce the maximum | r| value and result in the fast relaxation of correlated coherent states with | r| → 0. The effect of dissipation in real systems is weaker than the action of the stochastic force. It has been shown that the formation of correlated coherent states at the fast expansion of the well can underlie the mechanism of nuclear reactions at a low energy, e.g., in microcracks developing in the bulk of metal hydrides loaded with hydrogen or deuterium, as well as in a low-pressure plasma in a variable magnetic field in which the motion of ions is similar to a harmonic oscillator with a variable frequency.
Bojarski, P; Kawski, A
1993-06-01
The correlation effect in two-component systems of different viscosities was analyzed based on a concentration depolarization experiment. The inclusion of a correlation effect was found to be fully justified only in systems for which the localization time, τl, is considerably shorter than that of the rotational relaxation, τrot. On the grounds of an approximate analysis, taking into account the competition between the concentration and the rotational depolarization, it was possible to explain the concentration changes in the emission anisotropy in the systems investigated.
NASA Astrophysics Data System (ADS)
Qiu, H.-J.; Xu, Hai-Tao; Liu, Li; Wang, Yu
2014-12-01
Nanoporous metals produced by dealloying have shown great promise in many areas such as catalysis/electrocatalysis, energy conversion/storage, sensing/biosensing, actuation, and surface-enhanced Raman scattering. Particularly, nanoscale metal ligaments with high electronic conductivity, tunable size and rich surface chemistry make nanoporous metals very promising as catalysts/electrocatalysts for energy conversion applications such as fuel cells and also as versatile three-dimensional substrates for energy-storage in supercapacitors and lithium ion batteries. In this review, we focus on the recent developments of dealloyed nanoporous metals in both catalysis/electrocatalysis and energy storage. In particular, based on the state-of-the-art electron microscopy characterization, we explain the atomic origin of the high catalytic activity of nanoporous gold. We also highlight the recent advances in rationally designing nanoporous metal-based composites and hierarchical structures for enhanced energy storage. Finally, we conclude with some outlook and perspectives with respect to future research on dealloyed nanoporous metals in catalysis- and energy-related applications.
Qiu, H-J; Xu, Hai-Tao; Liu, Li; Wang, Yu
2015-01-14
Nanoporous metals produced by dealloying have shown great promise in many areas such as catalysis/electrocatalysis, energy conversion/storage, sensing/biosensing, actuation, and surface-enhanced Raman scattering. Particularly, nanoscale metal ligaments with high electronic conductivity, tunable size and rich surface chemistry make nanoporous metals very promising as catalysts/electrocatalysts for energy conversion applications such as fuel cells and also as versatile three-dimensional substrates for energy-storage in supercapacitors and lithium ion batteries. In this review, we focus on the recent developments of dealloyed nanoporous metals in both catalysis/electrocatalysis and energy storage. In particular, based on the state-of-the-art electron microscopy characterization, we explain the atomic origin of the high catalytic activity of nanoporous gold. We also highlight the recent advances in rationally designing nanoporous metal-based composites and hierarchical structures for enhanced energy storage. Finally, we conclude with some outlook and perspectives with respect to future research on dealloyed nanoporous metals in catalysis- and energy-related applications.
NASA Technical Reports Server (NTRS)
Wise, P H; Serijan, K T; Goodman, I A
1951-01-01
As part of a program to study the correlation between molecular structure and physical properties of high-density hydrocarbons, the net heats of combustion, melting points, boiling points, densities, and kinematic viscosities of some hydrocarbons in the 2-n-alkylbiphenyl, 1,1-diphenylalkane, diphenylalkane, 1,1-dicyclohexylalkane, and dicyclohexylalkane series are presented.
Carraway, K L; Koland, J G; Cerione, R A
1989-05-25
Fluorescence resonance energy transfer between epidermal growth factor (EGF) molecules, labeled with fluorescent reporter groups, was used as a monitor for EGF receptor-receptor interactions in plasma membranes isolated from human epidermoid A431 cells. Epidermal growth factor molecules labeled at the amino terminus with fluorescein isothiocyanate served as donor molecules in these energy transfer measurements, while EGF molecules labeled with eosin isothiocyanate at the amino terminus served as the energy acceptors. Both of these derivatives were shown to be active in binding to membrane receptors and in the activation of the endogenous receptor/tyrosine kinase activity. We found that membranes in the absence of added metal ion activators showed relatively little energy transfer (approximately 10% donor quenching) between the labeled growth factors. However, divalent metal ion activators of the EGF receptor/tyrosine kinase caused a significant increase in the extent of energy transfer between the labeled EGF molecules. Specifically, in the presence of 20 mM MgCl2, the extent of quenching of the donor fluorescence increased to 25% (from 10% in the absence of metal), while in the presence of 4 mM MnCl2, the extent of energy transfer was increased still further to 40-50%. The addition of an excess of EDTA resulted in the reversal of the observed energy transfer to basal levels. The increased energy transfer in the presence of these divalent cations correlated well with the ability of these metals to stimulate the EGF receptor/tyrosine kinase activity. However, the extent of receptor-receptor interactions measured by energy transfer was independent of receptor autophosphorylation. Overall, these results suggest that conditions under which the EGF receptor is primed to be active as a tyrosine kinase, within a lipid milieu, result in an increased aggregation of the receptor.
Słupski, R; Jankowski, K; Flores, J R
2016-09-14
Accurate Møller-Plesset (MP2) correlation energies calculated by means of the variational-perturbation and the finite-element methods are presented for several members of the Cu(+) isoelectronic series (N = 28), which represent closed-shell systems containing for the first time the 3d(10)-electron configuration and, consequently, closed M-shell. Total MP2 energies as well as their inner- and inter-shell components are reported for Cu(+), Zn(2+), Ge(4+), Kr(8+), Sr(10+), and Cd(20+). We found that for these ions the Z-dependence of the total MP2 energies is significantly weaker than for the members of the Ar-like series. The origin of this fact is rationalized by a detailed analysis performed at the levels of the shell- and inter-shell contributions to the MP2 energies. To get, for the first time, more general information about the (N, Z) characteristics of the MP2 energies for closed-shell atomic systems, we compare the Z-dependence of the Cu(+)-like systems with the MP2 energies calculated for other isoelectronic series. The weak Z-dependence is found for the He-, Ne-, and Cu(+)-like series, which consist of atoms having perfectly closed-shell K-, KL-, and KLM-electronic structures, respectively. In turn, for the Be-, Mg-, and Ar-series, the Z-dependence is considerably stronger.
NASA Astrophysics Data System (ADS)
Tsuzuki, Seiji; Honda, Kazumasa; Uchimaru, Tadafumi; Mikami, Masuhiro
2005-04-01
The intermolecular interaction energy of the toluene dimer has been calculated with the ARS-F model (a model chemistry for the evaluation of intermolecular interaction energy between ARomatic Systems using Feller's method), which was formerly called as the AIMI model III. The CCSD(T) (coupled cluster calculations with single and double substitutions with noniterative triple excitations) interaction energy at the basis set limit has been estimated from the second-order Møller-Plesset perturbation interaction energy at the basis set limit obtained by Feller's method and the CCSD(T) correction term obtained using a medium-size basis set. The cross (C2) dimer has the largest (most negative) interaction energy (-4.08kcal/mol). The antiparallel (C2h) and parallel (CS) dimers (-3.77 and -3.41kcal/mol, respectively) are slightly less stable. The dispersion interaction is found to be the major source of attraction in the toluene dimer. The dispersion interaction mainly determines the relative stability of the stacked three dimers. The electrostatic interaction of the stacked three dimers is repulsive. Although the T-shaped and slipped-parallel benzene dimers are nearly isoenergetic, the stacked toluene dimers are substantially more stable than the T-shaped toluene dimer (-2.62kcal/mol). The large dispersion interaction in the stacked toluene dimers is the cause of their enhanced stability.
Jing, Linhong; Nash, John J; Kenttämaa, Hilkka I
2008-12-31
The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropyl alcohol, were measured for 23 structurally different, positively charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for the reaction of three of the aryl radicals with isopropyl alcohol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of 15 different hydrogen-atom donors with two selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X-H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of 29 different aryl radicals and 18 different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be "tuned" by structural changes that influence either the vertical EA of the aryl radical or the vertical IE of the hydrogen atom donor.
NASA Astrophysics Data System (ADS)
Kalin, M.; Polajnar, M.
2014-02-01
The importance of wetting is becoming increasingly obvious and its control is inevitable in many engineering applications, including tribology and interface nanotechnology. However, the relations between the key parameters affecting surface-liquid wetting behaviour under realistic conditions are not very well understood, especially for typical engineering materials and lubricants (oils), often leading to exceptions and contradictions, which impede their use in engineering models and theories, and so the possible optimisation of the interfaces of engineering systems. In this paper we present the correlations between the contact angle, the spreading, the surface tension and the surface energy of fourteen frequently used engineering materials belonging to four different classes of materials (steel, DLC coatings, ceramics, and polymers) wetted with four different liquids: three oils (a non-polar synthetic oil of two different viscosities and a polar natural-based oil) and water. The results represent systematically and consistently obtained data about the wetting-relevant parameters of the selected materials and lubricants and numerous correlations between them. However, the most striking result suggests that the spreading parameter correlates very linearly with the surface energy for all the materials and liquids studied, in both the adhesion-wetting and spreading-wetting regimes. The experimentally determined spreading vs. surface energy correlation functions that appear generally valid for a broad range of properties of the materials and oils can thus be applied as an engineering tool to tailor and design the required/desired wetting performance and nature of the solid-liquid interfaces. The spreading parameter SP - in contrast to the contact angle - was found to be a reliable and relevant parameter for describing the wetting of oils with selected engineering materials.
Buchta, D.; Stienkemeier, F.; Mudrich, M.; Krishnan, S. R.; Moshammer, R.; Brauer, N. B.; Drabbels, M.; O’Keeffe, P.; Coreno, M.; Devetta, M.; Di Fraia, M.; Callegari, C.; Richter, R.; Prince, K. C.; Ullrich, J.
2013-08-28
The ionization dynamics of pure He nanodroplets irradiated by Extreme ultraviolet radiation is studied using Velocity-Map Imaging PhotoElectron-PhotoIon COincidence spectroscopy. We present photoelectron energy spectra and angular distributions measured in coincidence with the most abundant ions He{sup +}, He{sub 2}{sup +}, and He{sub 3}{sup +}. Surprisingly, below the autoionization threshold of He droplets, we find indications for multiple excitation and subsequent ionization of the droplets by a Penning-like process. At high photon energies we observe inelastic collisions of photoelectrons with the surrounding He atoms in the droplets.
Vysotskii, V. I. Vysotskyy, M. V.
2015-02-15
A method for the formation of correlated coherent states of low-energy particles in a parabolic potential well owing to the full-scale low-frequency modulation ω(t) = ω{sub 0}sinΩt of the parameters of this well has been considered. It has been shown that such a modulation in the absence of a stochastic force acting on a particle results in the fast formation of correlated coherent states and in an increase in the correlation coefficient and transparency of the potential barrier to the limiting values vertical bar r(t) vertical bar {sub max} → 1 and D → 1. The presence of the stochastic force significantly affects the evolution of correlated coherent states, decreasing the rate of an increase in the correlation coefficient vertical bar r(t) vertical bar {sub max} (at Ω ≤ 10{sup −4}ω{sub 0}) and limiting it at the level vertical bar r(∞) vertical bar {sub max} < 1 (at Ω = (0.001–0.1)ω{sub 0}); vertical bar r(∞) vertical bar {sub max} increases with a decrease in the frequency of modulation and decreases with an increase in the intensity of the stochastic force. It has been shown that, at a realistic relation between the parameters, low-frequency modulation can ensure such vertical bar r vertical bar {sub max} value that the transparency of the potential barrier for low-energy particles increases by a factor of 10{sup 50}–10{sup 100} or larger. The mechanism of the formation of correlated coherent states for charged particles in a gas or a low-pressure plasma placed in a low-frequency magnetic field has been considered. We have determined the relation between the magnetic field strength and modulation frequency, as well as the relation between the temperature and density of the gas (plasma), at which the method under consideration can be used to optimize nuclear reactions at low energies.
2003-01-01
Canada, Britain, and Spain. We found that the energy industry is not in crisis ; however, U.S. government policies, laws, dollars, and even public...CEIMAT (Centro de Investagaciones Energeticas , Medioambeintales y Tecnologicas) Research and development Page 3 of 28ENERGY 8/10/04http://www.ndu.edu...procurement or storage of standard, common use fuels. NATURAL GAS Natural gas, abundant globally and domestically, offers energy versatility among
Chakraborty, Subrata; Vijay, Amrendra
2016-04-14
Using a second-quantized many-electron Hamiltonian, we obtain (a) an effective Hamiltonian suitable for materials whose electronic properties are governed by a set of strongly correlated bands in a narrow energy range and (b) an effective spin-only Hamiltonian for magnetic materials. The present Hamiltonians faithfully include phonon and spin-related interactions as well as the external fields to study the electromagnetic response properties of complex materials and they, in appropriate limits, reduce to the model Hamiltonians due to Hubbard and Heisenberg. With the Hamiltonian for narrow-band strongly correlated materials, we show that the spin-orbit interaction provides a mechanism for metal-insulator transition, which is distinct from the Mott-Hubbard (driven by the electron correlation) and the Anderson mechanism (driven by the disorder). Next, with the spin-only Hamiltonian, we demonstrate the spin-orbit interaction to be a reason for the existence of antiferromagnetic phase in materials which are characterized by a positive isotropic spin-exchange energy. This is distinct from the Néel-VanVleck-Anderson paradigm which posits a negative spin-exchange for the existence of antiferromagnetism. We also find that the Néel temperature increases as the absolute value of the spin-orbit coupling increases.
NASA Astrophysics Data System (ADS)
Gotsman, E.; Levin, E.; Maor, U.
2016-11-01
In the framework of our model of soft interactions at high energy based on the CGC/saturation approach, we show that Bose-Einstein correlations of identical gluons lead to large values of v_n. We demonstrate how three dimensional scales of high energy interactions, hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of v_n. Our calculation shows that the structure of the `dressed' Pomeron leads to values of v_n which are close to experimental values for proton-proton scattering, 20 % smaller than the observed values for proton-lead collisions and close to lead-lead collisions for 0-10 % centrality. Bearing this result in mind, we conclude that it is premature to consider that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark-gluon plasma.
NASA Astrophysics Data System (ADS)
McCarty, J.; Clark, A. J.; Copperman, J.; Guenza, M. G.
2014-05-01
Structural and thermodynamic consistency of coarse-graining models across multiple length scales is essential for the predictive role of multi-scale modeling and molecular dynamic simulations that use mesoscale descriptions. Our approach is a coarse-grained model based on integral equation theory, which can represent polymer chains at variable levels of chemical details. The model is analytical and depends on molecular and thermodynamic parameters of the system under study, as well as on the direct correlation function in the k → 0 limit, c0. A numerical solution to the PRISM integral equations is used to determine c0, by adjusting the value of the effective hard sphere diameter, dHS, to agree with the predicted equation of state. This single quantity parameterizes the coarse-grained potential, which is used to perform mesoscale simulations that are directly compared with atomistic-level simulations of the same system. We test our coarse-graining formalism by comparing structural correlations, isothermal compressibility, equation of state, Helmholtz and Gibbs free energies, and potential energy and entropy using both united atom and coarse-grained descriptions. We find quantitative agreement between the analytical formalism for the thermodynamic properties, and the results of Molecular Dynamics simulations, independent of the chosen level of representation. In the mesoscale description, the potential energy of the soft-particle interaction becomes a free energy in the coarse-grained coordinates which preserves the excess free energy from an ideal gas across all levels of description. The structural consistency between the united-atom and mesoscale descriptions means the relative entropy between descriptions has been minimized without any variational optimization parameters. The approach is general and applicable to any polymeric system in different thermodynamic conditions.
McCarty, J.; Clark, A. J.; Copperman, J.; Guenza, M. G.
2014-05-28
Structural and thermodynamic consistency of coarse-graining models across multiple length scales is essential for the predictive role of multi-scale modeling and molecular dynamic simulations that use mesoscale descriptions. Our approach is a coarse-grained model based on integral equation theory, which can represent polymer chains at variable levels of chemical details. The model is analytical and depends on molecular and thermodynamic parameters of the system under study, as well as on the direct correlation function in the k → 0 limit, c{sub 0}. A numerical solution to the PRISM integral equations is used to determine c{sub 0}, by adjusting the value of the effective hard sphere diameter, d{sub HS}, to agree with the predicted equation of state. This single quantity parameterizes the coarse-grained potential, which is used to perform mesoscale simulations that are directly compared with atomistic-level simulations of the same system. We test our coarse-graining formalism by comparing structural correlations, isothermal compressibility, equation of state, Helmholtz and Gibbs free energies, and potential energy and entropy using both united atom and coarse-grained descriptions. We find quantitative agreement between the analytical formalism for the thermodynamic properties, and the results of Molecular Dynamics simulations, independent of the chosen level of representation. In the mesoscale description, the potential energy of the soft-particle interaction becomes a free energy in the coarse-grained coordinates which preserves the excess free energy from an ideal gas across all levels of description. The structural consistency between the united-atom and mesoscale descriptions means the relative entropy between descriptions has been minimized without any variational optimization parameters. The approach is general and applicable to any polymeric system in different thermodynamic conditions.
Vallinotto, Alberto; Viel, Matteo; Das, Sudeep; Spergel, David N.
2009-10-01
We expect a detectable correlation between two seemingly unrelated quantities: the four point function of the cosmic microwave background (CMB) and the amplitude of flux decrements in quasar (QSO) spectra. The amplitude of CMB convergence in a given direction measures the projected surface density of matter. Measurements of QSO flux decrements trace the small-scale distribution of gas along a given line-of-sight. While the cross-correlation between these two measurements is small for a single line-of-sight, upcoming large surveys should enable its detection. This paper presents analytical estimates for the signal to noise (S/N) for measurements of the cross-correlation between the flux decrement and the convergence, {delta}F{kappa}, and for measurements of the cross-correlation between the variance in flux decrement and the convergence, <({delta}F){sup 2}{kappa}>. For the ongoing BOSS (SDSS III) and Planck surveys, we estimate an S/N of 30 and 9.6 for these two correlations. For the proposed BigBOSS and ACTPOL surveys, we estimate an S/N of 130 and 50 respectively. Since <({delta}F){sup 2}{kappa}> {proportional_to} {delta}{sub s}{sup 4}, the amplitude of these cross-correlations can potentially be used to measure the amplitude of {delta}{sub 8} at z {approx} 2 to 2.5% with BOSS and Planck and even better with future data sets. These measurements have the potential to test alternative theories for dark energy and to constrain the mass of the neutrino. The large potential signal estimated in our analytical calculations motivate tests with non-linear hydrodynamical simulations and analyses of upcoming data sets.
NASA Astrophysics Data System (ADS)
Redondo-Cubero, A.; Galiana, B.; Lorenz, K.; Palomares, FJ; Bahena, D.; Ballesteros, C.; Hernandez-Calderón, I.; Vázquez, L.
2016-11-01
We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the ion species on the pattern ordering and properties. For the higher ordered patterns produced by Xe+ ions, the pattern wavelength depends linearly on the ion energy. The dot nanostructures are silicide-rich as assessed by x-ray photoelectron spectroscopy (XPS) and emerge in height due to their lower sputtering yield, as observed by electron microscopy. Remarkably, a long wavelength corrugation is observed on the surface which is correlated with both the Mo content and the dot pattern properties. Thus, as assessed by electron microscopy, the protrusions are Mo-rich with higher and more spaced dots on their surface whereas the valleys are Mo-poor with smaller dots that are closer to each other. These findings indicate that there is a correlation between the local metal content of the surface and the nanodot pattern properties both at the nanodot and the large corrugation scales. These results contribute to advancing the understanding of this interesting nanofabrication method and aid in developing a comprehensive theory of nanodot pattern formation and evolution.
NASA Astrophysics Data System (ADS)
Dixit, Anant; Ángyán, János G.; Rocca, Dario
2016-09-01
A new formalism was recently proposed to improve random phase approximation (RPA) correlation energies by including approximate exchange effects [B. Mussard et al., J. Chem. Theory Comput. 12, 2191 (2016)]. Within this framework, by keeping only the electron-hole contributions to the exchange kernel, two approximations can be obtained: An adiabatic connection analog of the second order screened exchange (AC-SOSEX) and an approximate electron-hole time-dependent Hartree-Fock (eh-TDHF). Here we show how this formalism is suitable for an efficient implementation within the plane-wave basis set. The response functions involved in the AC-SOSEX and eh-TDHF equations can indeed be compactly represented by an auxiliary basis set obtained from the diagonalization of an approximate dielectric matrix. Additionally, the explicit calculation of unoccupied states can be avoided by using density functional perturbation theory techniques and the matrix elements of dynamical response functions can be efficiently computed by applying the Lanczos algorithm. As shown by several applications to reaction energies and weakly bound dimers, the inclusion of the electron-hole kernel significantly improves the accuracy of ground-state correlation energies with respect to RPA and semi-local functionals.
Redondo-Cubero, A; Galiana, B; Lorenz, K; Palomares, F J; Bahena, D; Ballesteros, C; Hernandez-Calderón, I; Vázquez, L
2016-11-04
We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the ion species on the pattern ordering and properties. For the higher ordered patterns produced by Xe(+) ions, the pattern wavelength depends linearly on the ion energy. The dot nanostructures are silicide-rich as assessed by x-ray photoelectron spectroscopy (XPS) and emerge in height due to their lower sputtering yield, as observed by electron microscopy. Remarkably, a long wavelength corrugation is observed on the surface which is correlated with both the Mo content and the dot pattern properties. Thus, as assessed by electron microscopy, the protrusions are Mo-rich with higher and more spaced dots on their surface whereas the valleys are Mo-poor with smaller dots that are closer to each other. These findings indicate that there is a correlation between the local metal content of the surface and the nanodot pattern properties both at the nanodot and the large corrugation scales. These results contribute to advancing the understanding of this interesting nanofabrication method and aid in developing a comprehensive theory of nanodot pattern formation and evolution.
Momeni, Mohammad R; Brown, Alex
2015-06-09
The vertical excitation energies of 17 boron-dipyrromethene (BODIPY) core structures with a variety of substituents and ring sizes are benchmarked using time-dependent density functional theory (TD-DFT) with nine different functionals combined with the cc-pVTZ basis set. When compared to experimental measurements, all functionals provide mean absolute errors (mean AEs) greater than 0.3 eV, larger than the 0.1-0.3 eV differences typically expected from TD-DFT. Due to the high linear correlation of TD-DFT results with experiment, most functionals can be used to predict excitation energies if corrected empirically. Using the CAM-B3LYP functional, 0-0 transition energies are determined, and while the absolute difference is improved (mean AE = 0.478 eV compared to 0.579 eV), the correlation diminishes substantially (R(2) = 0.961 to 0.862). Two very recently introduced charge transfer (CT) indices, q(CT) and d(CT), and electron density difference (EDD) plots demonstrate that CT does not play a significant role for most of the BODIPYs examined and, thus, cannot be the source of error in TD-DFT. To assess TD-DFT methods, vertical excitation energies are determined utilizing TD-HF, configuration interaction CIS and CIS(D), equation of motion EOM-CCSD, SAC-CI, and Laplace-transform based local coupled-cluster singles and approximate doubles LCC2* methods. Moreover, multireference CASSCF and CASPT2 vertical excitation energies were also obtained for all species (except CASPT2 was not feasible for the four largest systems). The SAC-CI/cc-pVDZ, LCC2*/cc-pVDZ, and CASPT2/cc-pVDZ approaches are shown to have the smallest mean AEs of 0.154, 0.109, and 0.100 eV, respectively; the utility of the LCC2* approach is demonstrated for eight extended BODIPYs and aza-BODIPYs. We found that the problems with TD-DFT arise from difficulties in dealing with the differential electron correlation (as assessed by comparing CCS, CC2, LR-CCSD, CCSDR(T), and CCSDR(3) vertical excitation energies for
NASA Astrophysics Data System (ADS)
Pavošević, Fabijan; Pinski, Peter; Riplinger, Christoph; Neese, Frank; Valeev, Edward F.
2016-04-01
We present a formulation of the explicitly correlated second-order Møller-Plesset (MP2-F12) energy in which all nontrivial post-mean-field steps are formulated with linear computational complexity in system size. The two key ideas are the use of pair-natural orbitals for compact representation of wave function amplitudes and the use of domain approximation to impose the block sparsity. This development utilizes the concepts for sparse representation of tensors described in the context of the domain based local pair-natural orbital-MP2 (DLPNO-MP2) method by us recently [Pinski et al., J. Chem. Phys. 143, 034108 (2015)]. Novel developments reported here include the use of domains not only for the projected atomic orbitals, but also for the complementary auxiliary basis set (CABS) used to approximate the three- and four-electron integrals of the F12 theory, and a simplification of the standard B intermediate of the F12 theory that avoids computation of four-index two-electron integrals that involve two CABS indices. For quasi-1-dimensional systems (n-alkanes), the O (" separators="N ) DLPNO-MP2-F12 method becomes less expensive than the conventional O (" separators="N5 ) MP2-F12 for n between 10 and 15, for double- and triple-zeta basis sets; for the largest alkane, C200H402, in def2-TZVP basis, the observed computational complexity is N˜1.6, largely due to the cubic cost of computing the mean-field operators. The method reproduces the canonical MP2-F12 energy with high precision: 99.9% of the canonical correlation energy is recovered with the default truncation parameters. Although its cost is significantly higher than that of DLPNO-MP2 method, the cost increase is compensated by the great reduction of the basis set error due to explicit correlation.
NASA Astrophysics Data System (ADS)
Adare, Andrew M.
Quantum Chromodynamics (QCD) stands as a cornerstone of the standard model and describes interactions occurring at nuclear length scales with the distinctive concepts of color charge, asymptotic freedom, and confinement. As a consequence of these features, a nuclear phase composed of quarks and gluons rather than their composites is predicted to exist at extremely high temperatures and densities, which are nevertheless achievable in the lab through relativistic nuclear collisions. The experimental observation of this strongly-coupled quark gluon plasma (sQGP) phase of matter is of fundamental scientific interest for reasons including its presence in the early stages of the universe. Much information about the density of the sQGP, the nature of its coupling, and its transport properties can be inferred through the energy loss of fast partons generated by hard scattering processes in situ concurrently with the sQGP. These strongly-interacting particles radiate and scatter in their passage through the material before fragmenting into jets of observed color-neutral hadrons, and measurements of the correlated hadron production over a large event sample provide clues about the nature of partonic energy loss and its deposition into the hot nuclear material. In this analysis, azimuthal correlations between neutral pions at moderate to high transverse momentum (pT = 4-12 GeV/c) and associated unidentified charged hadrons (pT = 0.5-7 GeV/c) are presented in Au+Au and p+p collisions at sNN = 200 GeV. Interpretation of the correlations is simplified by the exclusive use of pi0 trigger particles, which reduces potential influences of recombination effects compared to unidentified dihadron correlations. In central Au+Au collisions, an alteration is observed in comparison to a p+p reference as partner pT increases. In the direction opposing moderate-momentum leading pi0s (4 < pT < 7 GeV/c), a medium-modified shape and enhanced yield evolves toward a suppressed but unmodified jet
Czarnecki, John B.; Stannard, David I.
1997-01-01
Franklin Lake playa is one of the principal discharge areas of the ground-water-flow system associated with Yucca Mountain, Nevada, the potential site of a high-level nuclear-waste repository. By using the energy-budget eddy-correlation technique, measurements made between June 1983 and April 1984 to estimate evapotranspiration were found to range from 0.1 centimeter per day during winter months to about 0.3 centimeter per day during summer months; the annual average was 0.16 centimeter per day. These estimates were compared with evapotranspiration estimates calculated from six other methods.
Hübsch, P; Schneider, B; Seidl, G; Kalchhauser, G; Klaushofer, K; Popovic, R
1991-07-01
The bone mineral density measurements of three different instruments at the femoral head were compared using 12 cadaver specimens. Two of these instruments were operated by x-rays (dual energy x-ray absorptiometry = DEXA), whereas one system was based on a gadolinium source (dual photon absorptiometry = DPA). Although excellent correlation between the measurements was obtained (r greater than 0,9), the measurements of one of the DEXA-instruments were significantly higher than the measurements of the two other systems. We conclude that a comparison of bone mineral density measurements obtained on different densitometry instruments may pose problems. Follow-up examinations should be done on one single densitometry unit.
Wu, Y.Q; Tang, W.; Kramer, M.J.; Dennis, K.W.; Oster, N.; McCallum, R.W.; Anderson, I.E.
2009-07-24
The devitrification behavior of nanocrystalline MRE{sub 2}(Fe,Co){sub 14}B+ZrC (MRE = Nd+Y+Dy) was studied using differential scanning calorimetry (DSC), synchrotron high temperature x-ray diffraction, and analytical transmission electron microscopy (TEM) techniques. Alloy ribbons were melt spun at 25 m/s to obtain an amorphous structure. Optimum hard magnetic properties (B{sub r} = 7.2 kG, H{sub c} = 12.7 kOe and (BH){sub max} = 10.8 MG Oe) were obtained in ribbons annealed at 750 C for 15 min. A reduced annealing temperature of 638 C and holding time from 0 to 11 min were chosen based on DSC analysis. Large changes in both microstructure and hard magnetic properties were found in a narrow window of annealing time, 4.5-6 min, resulting in a dramatic increase in energy product, remanence and coercivity: 0.96 MG Oe, 5.2 kG, 2.7 kOe to 5.7 MG Oe, 7.2 kG, 8.5 kOe for (BH){sub max}, B{sub r} and H{sub c}, respectively. Energy dispersive x-ray spectroscopy and energy filtered TEM analyses indicate that Zr- and C-rich particles ({approx} 5 nm) and thin grain boundary layers (1-2 nm thick) are formed surrounding 2-14-1 hard phase grains when the annealing time is over 6 min. Further annealing resulted in a more distinct hard phase surrounded by a nonmagnetic grain boundary phase {approx} 1 nm in thickness. The thin grain boundary layer phase starts to disappear with annealing time over 11 min. The partitioning behavior of various elements at different annealing conditions appears to be associated with significant changes in magnetic properties, leading to an improved optimum microstructure.
Fontana, Roberta; Della Torre, Sara
2016-02-11
In female mammals, mechanisms have been developed, throughout evolution, to integrate environmental, nutritional and hormonal cues in order to guarantee reproduction in favorable energetic conditions and to inhibit it in case of food scarcity. This metabolic strategy could be an advantage in nutritionally poor environments, but nowadays is affecting women's health. The unlimited availability of nutrients, in association with reduced energy expenditure, leads to alterations in many metabolic pathways and to impairments in the finely tuned inter-relation between energy metabolism and reproduction, thereby affecting female fertility. Many energetic states could influence female reproductive health being under- and over-weight, obesity and strenuous physical activity are all conditions that alter the profiles of specific hormones, such as insulin and adipokines, thus impairing women fertility. Furthermore, specific classes of nutrients might affect female fertility by acting on particular signaling pathways. Dietary fatty acids, carbohydrates, proteins and food-associated components (such as endocrine disruptors) have per se physiological activities and their unbalanced intake, both in quantitative and qualitative terms, might impair metabolic homeostasis and fertility in premenopausal women. Even though we are far from identifying a "fertility diet", lifestyle and dietary interventions might represent a promising and invaluable strategy to manage infertility in premenopausal women.
Fontana, Roberta; Della Torre, Sara
2016-01-01
In female mammals, mechanisms have been developed, throughout evolution, to integrate environmental, nutritional and hormonal cues in order to guarantee reproduction in favorable energetic conditions and to inhibit it in case of food scarcity. This metabolic strategy could be an advantage in nutritionally poor environments, but nowadays is affecting women’s health. The unlimited availability of nutrients, in association with reduced energy expenditure, leads to alterations in many metabolic pathways and to impairments in the finely tuned inter-relation between energy metabolism and reproduction, thereby affecting female fertility. Many energetic states could influence female reproductive health being under- and over-weight, obesity and strenuous physical activity are all conditions that alter the profiles of specific hormones, such as insulin and adipokines, thus impairing women fertility. Furthermore, specific classes of nutrients might affect female fertility by acting on particular signaling pathways. Dietary fatty acids, carbohydrates, proteins and food-associated components (such as endocrine disruptors) have per se physiological activities and their unbalanced intake, both in quantitative and qualitative terms, might impair metabolic homeostasis and fertility in premenopausal women. Even though we are far from identifying a “fertility diet”, lifestyle and dietary interventions might represent a promising and invaluable strategy to manage infertility in premenopausal women. PMID:26875986
Hartmann, Lisa; Drewe-Boß, Philipp; Wießner, Theresa; Wagner, Gabriele; Geue, Sascha; Lee, Hsin-Chieh; Obermüller, Dominik M; Kahles, André; Behr, Jonas; Sinz, Fabian H; Rätsch, Gunnar; Wachter, Andreas
2016-11-01
Plants use light as source of energy and information to detect diurnal rhythms and seasonal changes. Sensing changing light conditions is critical to adjust plant metabolism and to initiate developmental transitions. Here, we analyzed transcriptome-wide alterations in gene expression and alternative splicing (AS) of etiolated seedlings undergoing photomorphogenesis upon exposure to blue, red, or white light. Our analysis revealed massive transcriptome reprogramming as reflected by differential expression of ∼20% of all genes and changes in several hundred AS events. For more than 60% of all regulated AS events, light promoted the production of a presumably protein-coding variant at the expense of an mRNA with nonsense-mediated decay-triggering features. Accordingly, AS of the putative splicing factor REDUCED RED-LIGHT RESPONSES IN CRY1CRY2 BACKGROUND1, previously identified as a red light signaling component, was shifted to the functional variant under light. Downstream analyses of candidate AS events pointed at a role of photoreceptor signaling only in monochromatic but not in white light. Furthermore, we demonstrated similar AS changes upon light exposure and exogenous sugar supply, with a critical involvement of kinase signaling. We propose that AS is an integration point of signaling pathways that sense and transmit information regarding the energy availability in plants.
Kraisler, Eli; Makov, Guy; Kelson, Itzhak
2010-10-15
The total energies and the spin states for atoms and their first ions with Z=1-86 are calculated within the the local spin-density approximation (LSDA) and the generalized-gradient approximation (GGA) to the exchange-correlation (xc) energy in density-functional theory. Atoms and ions for which the ground-state density is not pure-state v-representable are treated as ensemble v-representable with fractional occupations of the Kohn-Sham system. A recently developed algorithm which searches over ensemble v-representable densities [E. Kraisler et al., Phys. Rev. A 80, 032115 (2009)] is employed in calculations. It is found that for many atoms, the ionization energies obtained with the GGA are only modestly improved with respect to experimental data, as compared to the LSDA. However, even in those groups of atoms where the improvement is systematic, there remains a non-negligible difference with respect to the experiment. The ab initio electronic configuration in the Kohn-Sham reference system does not always equal the configuration obtained from the spectroscopic term within the independent-electron approximation. It was shown that use of the latter configuration can prevent the energy-minimization process from converging to the global minimum, e.g., in lanthanides. The spin values calculated ab initio fit the experiment for most atoms and are almost unaffected by the choice of the xc functional. Among the systems with incorrectly obtained spin, there exist some cases (e.g., V, Pt) for which the result is found to be stable with respect to small variations in the xc approximation. These findings suggest a necessity for a significant modification of the exchange-correlation functional, probably of a nonlocal nature, to accurately describe such systems.
Fokas, Alexander S; Cole, Daniel J; Chin, Alex W
2014-12-01
The trimeric Fenna-Mathews-Olson (FMO) complex of green sulphur bacteria is a well-studied example of a photosynthetic pigment-protein complex, in which the electronic properties of the pigments are modified by the protein environment to promote efficient excitonic energy transfer from antenna complexes to the reaction centres. By a range of simulation methods, many of the electronic properties of the FMO complex can be extracted from knowledge of the static crystal structure. However, the recent observation and analysis of long-lasting quantum dynamics in the FMO complex point to protein dynamics as a key factor in protecting and generating quantum coherence under laboratory conditions. While fast inter- and intra-molecular vibrations have been investigated extensively, the slow, conformational dynamics which effectively determine the optical inhomogeneous broadening of experimental ensembles has received less attention. The following study employs constrained geometric dynamics to study the flexibility in the protein network by efficiently generating the accessible conformational states from the published crystal structure. Statistical and principle component analyses reveal highly correlated low frequency motions between functionally relevant elements, including strong correlations between pigments that are excitonically coupled. Our analysis reveals a hierarchy of structural interactions which enforce these correlated motions, from the level of monomer-monomer interfaces right down to the α-helices, β-sheets and pigments. In addition to inducing strong spatial correlations across the conformational ensemble, we find that the overall rigidity of the FMO complex is exceptionally high. We suggest that these observations support the idea of highly correlated inhomogeneous disorder of the electronic excited states, which is further supported by the remarkably low variance (typically <5%) of the excitonic couplings of the conformational ensemble.
Mitin, Alexander V; van Wüllen, Christoph
2006-02-14
A two-component quasirelativistic Hamiltonian based on spin-dependent effective core potentials is used to calculate ionization energies and electron affinities of the heavy halogen atom bromine through the superheavy element 117 (eka-astatine) as well as spectroscopic constants of the homonuclear dimers of these atoms. We describe a two-component Hartree-Fock and density-functional program that treats spin-orbit coupling self-consistently within the orbital optimization procedure. A comparison with results from high-order Douglas-Kroll calculations--for the superheavy systems also with zeroth-order regular approximation and four-component Dirac results--demonstrates the validity of the pseudopotential approximation. The density-functional (but not the Hartree-Fock) results show very satisfactory agreement with theoretical coupled cluster as well as experimental data where available, such that the theoretical results can serve as an estimate for the hitherto unknown properties of astatine, element 117, and their dimers.
Bonente, Giulia; Passarini, Francesca; Cazzaniga, Stefano; Mancone, Carmine; Buia, Maria Cristina; Tripodi, Marco; Bassi, Roberto; Caffarri, Stefano
2008-01-01
To avoid photodamage, photosynthetic organisms have developed mechanisms to evade or dissipate excess energy. Lumen overacidification caused by light-induced electron transport triggers quenching of excited chlorophylls and dissipation of excess energy into heat. In higher plants participation of the PsbS protein as the sensor of low lumenal pH was clearly demonstrated. Although light-dependent energy quenching is a property of all photosynthetic organisms, large differences in amplitude and kinetics can be observed thus raising the question whether a single common mechanism is in action. We performed a detailed study of PsbS expression/accumulation in Chlamydomonas reinhardtii and investigated its accumulation in other algae and plants. We showed that PsbS cannot be detected in Chlamydomonas under a wide range of growth conditions. Overexpression of the endogenous psbs gene showed that the corresponding protein could not be addressed to the thylakoid membranes. Survey of different unicellular green algae showed no accumulation of anti-PsbS reactive proteins differently from multicellular species. Nevertheless, some unicellular species exhibit high energy quenching activity, suggesting that a PsbS-independent mechanism is activated. By correlating growth habitat and PsbS accumulation in different species, we suggest that during the evolution the light environment has been a determinant factor for the conservation/loss of the PsbS function.
NASA Technical Reports Server (NTRS)
Chiao, Raymond Y.; Kwiat, Paul G.; Steinberg, Aephraim M.
1992-01-01
The energy-time uncertainty principle is on a different footing than the momentum position uncertainty principle: in contrast to position, time is a c-number parameter, and not an operator. As Aharonov and Bohm have pointed out, this leads to different interpretations of the two uncertainty principles. In particular, one must distinguish between an inner and an outer time in the definition of the spread in time, delta t. It is the inner time which enters the energy-time uncertainty principle. We have checked this by means of a correlated two-photon light source in which the individual energies of the two photons are broad in spectra, but in which their sum is sharp. In other words, the pair of photons is in an entangled state of energy. By passing one member of the photon pair through a filter with width delta E, it is observed that the other member's wave packet collapses upon coincidence detection to a duration delta t, such that delta E(delta t) is approximately equal to planks constant/2 pi, where this duration delta t is an inner time, in the sense of Aharonov and Bohm. We have measured delta t by means of a Michelson interferometer by monitoring the visibility of the fringes seen in coincidence detection. This is a nonlocal effect, in the sense that the two photons are far away from each other when the collapse occurs. We have excluded classical-wave explanations of this effect by means of triple coincidence measurements in conjunction with a beam splitter which follows the Michelson interferometer. Since Bell's inequalities are known to be violated, we believe that it is also incorrect to interpret this experimental outcome as if energy were a local hidden variable, i.e., as if each photon, viewed as a particle, possessed some definite but unknown energy before its detection.
Zdziennicka, Anna; Szymczyk, Katarzyna; Jańczuk, Bronisław
2009-12-15
The measurements of the advancing contact angle for water, glycerol, diiodomethane and aqueous solutions of Triton X-100 (TX-100), Triton X-165 (TX-165), sodium dodecyl sulfate (SDDS), sodium hexadecyl sulfonate (SHDS), cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPyB) on quartz surface were carried out. On the basis of the contact angles values obtained for water, glycerol and diiodomethane the values of the Lifshitz-van der Waals component and electron-acceptor and electron-donor parameters of the acid-base component of the surface free energy of quartz were determined. The determined components and parameters of the quartz surface free energy were used for interpretation of the influence of nonionic, anionic and cationic surfactants on the wettability of the quartz. From obtained results it was appeared that the wettability of quartz by nonionic and anionic surfactants practically does not depend on the surfactants concentration in the range corresponding to their unsaturated monolayer at water-air interface and that there is linear dependence between adhesional and surface tension of aqueous solution of these surfactants. This dependence for TX-100, TX-165, SDDS and SHDS can be expressed by lines which slopes are positive. This slope and components of quartz surface free energy indicate that the interaction between the water molecules and quartz surface might be stronger than those between the quartz and surfactants molecules. So, the surface excess of surfactants concentration at the quartz-water interface is probably negative, and the possibility of surfactants to adsorb at the quartz/water film-water interface is higher than at the quartz-water interface. This conclusion is confirmed by the values of the adhesion work of "pure" surfactants, aqueous solutions of surfactants and water to quartz surface. In the case of the cationic surfactants the relationship between adhesional and surface tension is more complicated than that for
Qi, Helena W; Leverentz, Hannah R; Truhlar, Donald G
2013-05-30
This work presents a new fragment method, the electrostatically embedded many-body expansion of the nonlocal energy (EE-MB-NE), and shows that it, along with the previously proposed electrostatically embedded many-body expansion of the correlation energy (EE-MB-CE), produces accurate results for large systems at the level of CCSD(T) coupled cluster theory. We primarily study water 16-mers, but we also test the EE-MB-CE method on water hexamers. We analyze the distributions of two-body and three-body terms to show why the many-body expansion of the electrostatically embedded correlation energy converges faster than the many-body expansion of the entire electrostatically embedded interaction potential. The average magnitude of the dimer contributions to the pairwise additive (PA) term of the correlation energy (which neglects cooperative effects) is only one-half of that of the average dimer contribution to the PA term of the expansion of the total energy; this explains why the mean unsigned error (MUE) of the EE-PA-CE approximation is only one-half of that of the EE-PA approximation. Similarly, the average magnitude of the trimer contributions to the three-body (3B) term of the EE-3B-CE approximation is only one-fourth of that of the EE-3B approximation, and the MUE of the EE-3B-CE approximation is one-fourth that of the EE-3B approximation. Finally, we test the efficacy of two- and three-body density functional corrections. One such density functional correction method, the new EE-PA-NE method, with the OLYP or the OHLYP density functional (where the OHLYP functional is the OptX exchange functional combined with the LYP correlation functional multiplied by 0.5), has the best performance-to-price ratio of any method whose computational cost scales as the third power of the number of monomers and is competitive in accuracy in the tests presented here with even the electrostatically embedded three-body approximation.
Carnall, W.T.; Beitz, J.V.; Crosswhite, H.
1984-03-15
The solution absorption spectrum of Bk/sup 3 +/(aquo) was measured and the observed band structure interpreted in terms of a free-ion energy level model. The band intensities were successfully analyzed using the Judd--Ofelt theory for transitions within the f/sup tsN/ configuration. Parameters of the theory were then used to compute fluorescence branching ratios from most probable fluorescing states, and an experimental search was successful in yielding evidence for a transition from one excited state to the ground state in D/sub 2/O solvent. Absorption bands attributed to f ..-->.. d transitions were observed and an interpretation of the electronic structure is presented. Band intensities were compared to those observed for Tb/sup 3 +/(aquo).
Wolf, K.L.
1996-12-31
Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An upgraded multiple-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-ion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization.
NASA Technical Reports Server (NTRS)
Coyne, Lelia M.; Banin, Amos; Carle, Glenn; Orenberg, James; Scattergood, Thomas
1989-01-01
A number of questions concerning the surface mineralogy and the history of water on Mars remain unresolved using the Viking analyses and Earth-based telescopic data. Identification and quantitation of iron-bearing clays on Mars would elucidate these outstanding issues. Near infrared correlation analysis, a method typically applied to qualitative and quantitative analysis of individual constituents of multicomponent mixtures, is adapted here to selection of distinctive features of a small, highly homologous series of Fe/Ca-exchanged montmorillonites and several kalinites. Independently determined measures of surface iron, relative humidity and stored electronic energy were used as constituent data for linear regression of the constituent vs. reflectance data throughout the spectral region 0.68 to 2.5 micrometers. High correlations were found in appropriate regions for all three constituents, though that with stored energy is still considered tenuous. Quantitation was improved using 1st and 2nd derivative spectra. High resolution data over a broad spectral range would be required to quantitatively identify iron-bearing clays by remotely sensed reflectance.
Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio
2013-01-01
Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871
NASA Astrophysics Data System (ADS)
Runge, Keith; Deymier, Pierre
2013-03-01
Recent progress in orbital-free Density Functional Theory (OF-DFT), particularly with regard to temperature dependent functionals, has promise for the simulation of warm dense matter (WDM) systems. WDM includes systems with densities of an order of magnitude beyond ambient or more and temperatures measured in kilokelvin. A challenge for the development of temperature dependent OF-DFT functionals is the lack of benchmark information with temperature and pressure dependence on simple models under WDM conditions. We present an approach to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Electrons are described as harmonic necklaces within the discrete path integral representation while quantum exchange takes the form of cross linking between electron necklaces. A molecular dynamics algorithm is used to sample phase space and the fermion sign problem is addressed by restricting the density matrix to positive values. The temperature dependence of kinetic energies for the strongly coupled electron plasma is presented for a number of Wigner-Seitz radii in terms of a fourth order Sommerfeld expansion. Supported by US DoE Grant DE-SC0002139
NASA Astrophysics Data System (ADS)
Chen, Jiqiang; Krieger, J. B.; Li, Yan; Iafrate, G. J.
1996-11-01
We have investigated the accuracy of the local-spin-density approximation with orbital-density-dependent self-interaction correction (LSDSIC) as proposed by Perdew and Zunger within a Kohn-Sham approach in which electrons with a given spin projection all move in a single optimized effective potential (OEP). We have also studied the accuracy of the Krieger-Li-Iafrate (KLI) approximation to the OEP for the same energy functional in order to assess its applicability to systems in which the integral equation for the OEP cannot be reduced to a one-dimensional problem, e.g., molecules. Self-consistent Kohn-Sham LSDSIC calculations have been performed for atoms with atomic number Z=1-20 in the exchange-only case for the total energy, the highest-occupied orbital energy ɛm, and the expectation value of r2. In addition, the structure of the resulting exchange potential is examined and compared with the exact exchange-only density-functional theory (OEP method with Hartree-Fock exchange-energy functional) results. Furthermore, we display ɛm, the ionization potential I, and the electron affinity A when both exchange and correlation energy effects are included. Finally, we also consider the results of evaluating the LSDSIC energy functional by employing the exact (in the central-field approximation) single particle orbitals as proposed by Harrison. We find that the LSDSIC energy functional generally leads to calculated values that are superior to those provided by the LSD approximation and that the KLI approximation yields results in excellent agreement with the corresponding exact OEP results for this energy functional. In particular, quantities strongly related to the behavior of the valence electrons are nearly identical in both the OEP and KLI calculations, i.e., the difference between the
NASA Technical Reports Server (NTRS)
Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.
2013-01-01
Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.
NASA Astrophysics Data System (ADS)
Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.
2013-11-01
extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.
ERIC Educational Resources Information Center
Shanebrook, J. Richard
This document describes a course designed to acquaint students with the many societal and technological problems facing the United States and the world due to the increasing demand for energy. The course begins with a writing assignment that involves readings on the environmental philosophy of Native Americans and the Chernobyl catastrophe.…
NASA Technical Reports Server (NTRS)
Schlosser, H.
1981-01-01
The self consistent calculation of the electronic energy levels of noble gas pseudomolecules formed when a metal surface is bombarded by noble gas ions is discussed along with the construction of energy level correlation diagrams as a function of interatomic spacing. The self consistent field x alpha scattered wave (SCF-Xalpha-SW) method is utilized. Preliminary results on the Ne-Mg system are given. An interactive x alpha programming system, implemented on the LeRC IBM 370 computer, is described in detail. This automated system makes use of special PROCDEFS (procedure definitions) to minimize the data to be entered manually at a remote terminal. Listings of the special PROCDEFS and of typical input data are given.
Correlation-corrected energy bands of YBa{sub 2}Cu{sub 3}O{sub 7}: A mutually consistent treatment
Wechsler, D.; Ladik, J.
1997-04-01
The band structures and density of states (DOS) of important subunits (Cu-O planes and chains, both including apical oxygens) in YBa{sub 2}Cu{sub 3}O{sub 7} were computed. As a first step we employed an {ital ab initio} Hartree-Fock (HF) crystal-orbital method to both subunits in a mutually consistent way embedding them also in a partially self-consistent Madelung potential of the 3D crystal. Afterwards the bands were corrected for correlation by a Green{close_quote}s-function method in second order of the Mo/ller-Plesset many-body perturbation theory. The main purpose of these rather large-scale calculations was to obtain reliable unfilled energy bands to be used in subsequent exciton bands calculations. This will make it possible to look more thoroughly at the proposed excitonic (polarization) mechanism of high-T{sub c} superconductivity. A comparison with calculations based on a local-density-functional (LDF) approximation showed good agreement to our approach in the valence-band energy region above {minus}8 eV while the LDF results agree well with experimental photoelectron spectra. In contrast to the LDF methods, we detected between {minus}8 and {minus}12 eV flat Cu3d energy bands, which correspond to satellite structures observed by experiment. {copyright} {ital 1997} {ital The American Physical Society}
Ivanov, Sergei D. Grant, Ian M.; Marx, Dominik
2015-09-28
With the goal of computing quantum free energy landscapes of reactive (bio)chemical systems in multi-dimensional space, we combine the metadynamics technique for sampling potential energy surfaces with the ab initio path integral approach to treating nuclear quantum motion. This unified method is applied to the double proton transfer process in the formic acid dimer (FAD), in order to study the nuclear quantum effects at finite temperatures without imposing a one-dimensional reaction coordinate or reducing the dimensionality. Importantly, the ab initio path integral metadynamics technique allows one to treat the hydrogen bonds and concomitant proton transfers in FAD strictly independently and thus provides direct access to the much discussed issue of whether the double proton transfer proceeds via a stepwise or concerted mechanism. The quantum free energy landscape we compute for this H-bonded molecular complex reveals that the two protons move in a concerted fashion from initial to product state, yet world-line analysis of the quantum correlations demonstrates that the protons are as quantum-uncorrelated at the transition state as they are when close to the equilibrium structure.
Ivanov, Sergei D; Grant, Ian M; Marx, Dominik
2015-09-28
With the goal of computing quantum free energy landscapes of reactive (bio)chemical systems in multi-dimensional space, we combine the metadynamics technique for sampling potential energy surfaces with the ab initio path integral approach to treating nuclear quantum motion. This unified method is applied to the double proton transfer process in the formic acid dimer (FAD), in order to study the nuclear quantum effects at finite temperatures without imposing a one-dimensional reaction coordinate or reducing the dimensionality. Importantly, the ab initio path integral metadynamics technique allows one to treat the hydrogen bonds and concomitant proton transfers in FAD strictly independently and thus provides direct access to the much discussed issue of whether the double proton transfer proceeds via a stepwise or concerted mechanism. The quantum free energy landscape we compute for this H-bonded molecular complex reveals that the two protons move in a concerted fashion from initial to product state, yet world-line analysis of the quantum correlations demonstrates that the protons are as quantum-uncorrelated at the transition state as they are when close to the equilibrium structure.
Wang Tao; Gu Qiusheng; Huang Jiasheng; Fang Guanwen; Fazio, G. G.; Faber, S. M.; McGrath, Elizabeth J.; Kocevski, Dale; Yan Haojing; Dekel, Avishai; Guo Yicheng; Ferguson, Henry C.; Grogin, Norman; Lotz, Jennifer M.; Lucas, Ray A.; Koekemoer, A. M.; Weiner, Benjamin; Hathi, Nimish P.; Kong Xu
2012-06-20
We present a study on spectral energy distributions, morphologies, and star formation for an IRAC-selected extremely red object sample in the GOODS Chandra Deep Field-South. This work was enabled by new HST/WFC3 near-IR imaging from the CANDELS survey as well as the deepest available X-ray data from Chandra 4 Ms observations. This sample consists of 133 objects with the 3.6 {mu}m limiting magnitude of [3.6] = 21.5 and is approximately complete for galaxies with M{sub *} > 10{sup 11} M{sub Sun} at 1.5 {<=} z {<=} 2.5. We classify this sample into two types, quiescent and star-forming galaxies (SFGs), in the observed infrared color-color ([3.6]-[24] versus K - [3.6]) diagram. The further morphological study of this sample shows a consistent result with the observed color classification. The classified quiescent galaxies are bulge dominated and SFGs in the sample have disk or irregular morphologies. Our observed infrared color classification is also consistent with the rest-frame color (U - V versus V - J) classification. We also found that quiescent and SFGs are well separated in the nonparametric morphology parameter (Gini versus M{sub 20}) diagram measuring their concentration and clumpiness: quiescent galaxies have a Gini coefficient higher than 0.58 and SFGs have a Gini coefficient lower than 0.58. We argue that the star formation quenching process must lead to or be accompanied by the increasing galaxy concentration. One prominent morphological feature of this sample is that disks are commonly seen in this massive galaxy sample at 1.5 {<=} z {<=} 2.5: 30% of quiescent galaxies and 70% of SFGs with M{sub *} > 10{sup 11} M{sub Sun} have disks in their rest-frame optical morphologies. The prevalence of these extended, relatively undisturbed disks challenges the merging scenario as the main mode of massive galaxy formation.
Fang, Ke; Fujii, Toshihiro; Linden, Tim; Olinto, Angela V.
2014-10-20
The Telescope Array (TA) has observed a statistically significant excess in cosmic rays with energies above 57 EeV in a region of approximately 1150 deg{sup 2} centered on coordinates R.A. = 146.7, decl. = 43.2. We note that the location of this excess correlates with 2 of the 28 extraterrestrial neutrinos recently observed by IceCube. The overlap between the two IceCube neutrinos and the TA excess is statistically significant at the 2σ level. Furthermore, the spectrum and intensity of the IceCube neutrinos is consistent with a single source which would also produce the TA excess. Finally, we discuss possible source classes with the correct characteristics to explain the cosmic-ray and neutrino fluxes with a single source.
NASA Astrophysics Data System (ADS)
Shepherd, James J.; Henderson, Thomas M.; Scuseria, Gustavo E.
2016-03-01
Over the past few years, pair coupled cluster doubles (pCCD) has shown promise for the description of strong correlation. This promise is related to its apparent ability to match results from doubly occupied configuration interaction (DOCI), even though the latter method has exponential computational cost. Here, by modifying the full configuration interaction quantum Monte Carlo algorithm to sample only the seniority zero sector of Hilbert space, we show that the DOCI and pCCD energies are in agreement for a variety of 2D Hubbard models, including for systems well out of reach for conventional configuration interaction algorithms. Our calculations are aided by the sign problem being much reduced in the seniority zero space compared with the full space. We present evidence for this and then discuss the sign problem in terms of the wave function of the system which appears to have a simplified sign structure.
Arora, Priya; Moudgil, R. K.; Bhukal, Nisha
2015-05-15
Static density-density correlation function has been calculated for a spin-polarized two-dimensional quantum electron fluid by including the first-order exchange and self-energy corrections to the random-phase approximation (RPA). This is achieved by determining these corrections to the RPA linear density-density response function, obtained by solving the equation of motion for the single-particle Green’s function. Resulting infinite hierarchy of equations (involving higher-order Green’s functions) is truncated by factorizing the two-particle Green’s function as a product of the single-particle Green’s function and one-particle distribution function. Numerical results of correlation function are compared directly against the quantum Monte Carlo simulation data due to Tanatar and Ceperley for different coupling parameter (r{sub s}) values. We find almost exact agreement for r{sub s}=1, with a noticeable improvement over the RPA. Its quality, however, deteriorates with increasing r{sub s}, but correction to RPA is quite significant.
Energy levels of terbium(III) in the elpasolite Cs2NaTbBr6. II. A correlation crystal field analysis
NASA Astrophysics Data System (ADS)
McCaw, C. S.; Denning, R. G.
A set of more than 100 electronic energy levels in Cs2NaTbBr6, extending from the ground state to 5H4, is used to test different models of the correlation crystal field (CCF). These are based on Judd's orthogonal g(k)iQ two-electron operators, and more specifically on contributions due to spin-correlation, or ligand polarization. Similar data from Cs2NaTbCl6 and Cs2NaTbF6 has also been analysed. Only fourth-rank operators make clear improvements to the quality of the fit in deviant multiplets. Empirically the g7(4) and g9(4) operators are found to be the most effective. Although fourth-rank operators achieve modest success in correcting the calculated spread of the multiplets, no single operator has a significant impact on the shortcomings of the one-body crystal field. This result is discussed in terms of the limitations of an effective-operator Hamiltonian.
Guo, Wei; Sneed, Brian T.; Zhou, Lin; Tang, Wei; Kramer, Matthew J.; Cullen, David A.; Poplawsky, Jonathan D.
2016-12-21
Alnico alloys have long been used as strong permanent magnets because of their ferromagnetism and high coercivity. Understanding their structural details allows for better prediction of the resulting magnetic properties. However, quantitative three-dimensional characterization of the phase separation in these alloys is still challenged by the spatial quantification of nanoscale phases. Herein, we apply a dual tomography approach, where correlative scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopic (EDS) tomography and atom probe tomography (APT) are used to investigate the initial phase separation process of an alnico 8 alloy upon non-magnetic annealing. STEM-EDS tomography provides information on the morphology and volume fractions of Fe–Co-rich and Νi–Al-rich phases after spinodal decomposition in addition to quantitative information of the composition of a nanoscale volume. Subsequent analysis of a portion of the same specimen by APT offers quantitative chemical information of each phase at the sub-nanometer scale. Furthermore, APT reveals small, 2–4 nm Fe-rich
Guo, Wei; Sneed, Brian T.; Zhou, Lin; ...
2016-12-21
Alnico alloys have long been used as strong permanent magnets because of their ferromagnetism and high coercivity. Understanding their structural details allows for better prediction of the resulting magnetic properties. However, quantitative three-dimensional characterization of the phase separation in these alloys is still challenged by the spatial quantification of nanoscale phases. Herein, we apply a dual tomography approach, where correlative scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopic (EDS) tomography and atom probe tomography (APT) are used to investigate the initial phase separation process of an alnico 8 alloy upon non-magnetic annealing. STEM-EDS tomography provides information on the morphology andmore » volume fractions of Fe–Co-rich and Νi–Al-rich phases after spinodal decomposition in addition to quantitative information of the composition of a nanoscale volume. Subsequent analysis of a portion of the same specimen by APT offers quantitative chemical information of each phase at the sub-nanometer scale. Furthermore, APT reveals small, 2–4 nm Fe-rich α1 phases that are nucleated in the Ni-rich α2 matrix. From this information, we show that phase separation of the alnico 8 alloy consists of both spinodal decomposition and nucleation and growth processes. Lastly, we discuss the complementary benefits and challenges associated with correlative STEM-EDS and APT.« less
Takahashi, Yoshiyuki
1997-12-12
This report describes the research results of the study of high energy heavy-ion interactions and multi-cluster correlations at the University of Alabama in Huntsville (UAH). This study has been performed as the CERN experiments, EMU05, EMU09 and EMU16, and a part of the RHIC PHENIX and its MVD Collaboration work. Physics objectives and methods are described in chapters 1, 2, 3 and Appendices A1 and A2. The experimental set-up, measurements, an the data analyses at UAH are described in chapters 4 through 10 and Appendices. The UAH research was a quest for high density state of nuclear matter, in terms of finding analysis methods of multi-isospin correlations. The present work emphasized a study of the fluctuation of the particle density, discriminating the isospin for exploring the Disoriented Chiral Condensate (DCC). The analysis methods developed are: (1) Chi-square density test; (2) Run-test; (3) G-test; (4) Fourier analysis; and (5) Lomb`s Periodogram. The application of these methods for central collision events in 2,000 GeV/n S + Pb and 167 GeV/n Pb + Pb produced interesting DCC correlations for a few events. However, further investigation of fluctuations with Monte Carlo method guided them to understand various hidden degree of freedoms in such analyses. The results of the analysis of the experimental data in comparison with the Monte Carlo data did not support the DCC process as compelling. The developed methods evolved for a plan to investigate the DCC in the PHENIX. The study has obtained several mathematical analysis methods from the CERN EMU05/16 experiments for a possible use in RHIC experiments.
NASA Astrophysics Data System (ADS)
Witek, M.; Kang, T. S.; van der Lee, S.
2015-12-01
We have collected three-component data from 122 Korean accelerometer stations for the month of December in 2014. We apply similar techniques described by Zha et al. (2013) to retrieve accurate station orientation angles, in order to rotate the horizontal component data into the radial and transverse frame of reference, and for subsequent measurement of Love wave group velocity dispersion. We simultaneously normalize all three components of a daily noise record via the frequency-time normalization (FTN) method. Each component is divided by the average signal envelope in an effort to retain relative amplitude information between all three components. Station orientations are found by a grid search for the orientation azimuth which maximizes the coherency between the radial-vertical cross-correlation and the Hilbert transformed vertical-vertical cross-correlation. After measuring orientation angles, we cross-correlate and rotate the data. Typically, the group velocity dispersion curves are measured using the frequency time analysis technique (FTAN), effectively producing spectrograms with significant uncertainty in the time-frequency plane. The spectrogram approach retains only the amplitude information of the short-time Fourier transform (STFT). However, Kodera et al (1976) show that by taking into account the phase information, the concepts of instantaneous frequency and group-time delay can be used to compute the first moment of the signal power in the frequency and time domains. During energy reassignment, the signal power calculated using the STFT at a point (t0,f0t_0, f_0) is reassigned to the location of the first moment (t^g,f^ihat{t}_g,hat{f}_i), where t^ghat{t}_g is the group-time delay and f^ihat{f}_i is the instantaneous frequency. We apply the method of energy reassignment to produce precise Rayleigh and Love wave group velocity measurements in the frequency range 0.1 - 1.0 Hz. Tests on synthetic data show more accurate retrieval of group velocities at
NASA Astrophysics Data System (ADS)
Constantin, Paul
Two particle azimuthal correlation functions measured in pp and AuAu collisions at sNN = 200 GeV at midrapidity with the central arms of the PHENIX detector are analyzed in order to extract the properties of hadronic jets produced in QCD vacuum and highly excited QCD media, like the jet shape parameters jT and kT, the jet conditional yields (number of associated hadrons per high pT trigger hadron) and the jet fragmentation function. The analysis of pp data starts with the measurement of the vacuum fragmentation function from which the pT dependence of the mean fragmentation momentum fraction
NASA Astrophysics Data System (ADS)
Shastry, B. Sriram; Perepelitsky, Edward
2016-07-01
We present the results for the low-energy properties of the infinite-dimensional t -J model with J =0 , using O (λ2) equations of the extremely correlated Fermi liquid formalism. The parameter λ ∈[0 ,1 ] is analogous to the inverse spin parameter 1 /(2 S ) in quantum magnets. The present analytical scheme allows us to approach the physically most interesting regime near the Mott insulating state n ≲1 . It overcomes the limitation to low densities n ≲0.7 of earlier calculations, by employing a variant of the skeleton graph expansion, and a high-frequency cutoff that is essential for maintaining the known high-T entropy. The resulting quasiparticle weight Z , the low ω ,T self-energy, and the resistivity are reported. These are quite close at all densities to the exact numerical results of the U =∞ Hubbard model, obtained using the dynamical mean field theory. The present calculation offers the advantage of generalizing to finite T rather easily, and allows the visualization of the loss of coherence of Fermi liquid quasiparticles by raising T . The present scheme is generalizable to finite dimensions and a nonvanishing J .
Sancho-García, J C; Pérez-Jiménez, A J
2008-10-16
The current research on molecular-based devices built with highly unsaturated molecules is largely assisted by computational techniques. These modern computational tools are intended to serve (i) to understand the relation between the mechanism of charge transport and the chemical composition of the semiconductors and (ii) to perform the molecular engineering needed to design new and more efficient organic materials. We have studied the case of a rod-shaped conjugated molecule widely used in molecular electronics. The results of multireference perturbation theory up to second order (MRMP2) and complete active space self-consistent field calculations (CASSCF) are compared with the results provided by energy density functionals. Motivated by the diverse accuracy of the results depending on the theoretical method selected, we have systematically studied the physical origin of the discrepancies. We find that a subtle interplay between correlation effects and the self-interaction energy mainly governs the results, which makes it thus difficult to anticipate the quality of a method without knowing in advance its dependence on both effects. We thus encourage careful testing of computational methods for the rational design and understanding of conjugated materials for charge conduits.
Tobaruela, Almudena; Rojo, Francisco Javier; García Paez, José María; Bourges, Jean Yves; Herrero, Eduardo Jorge; Millán, Isabel; Alvarez, Lourdes; Cordon, Ángeles; Guinea, Gustavo V
2016-08-01
The aim of this study was to evaluate the variation of hardness with fatigue in calf pericardium, a biomaterial commonly used in bioprosthetic heart valves, and its relationship with the energy dissipated during the first fatigue cycle that has been shown to be a predictor of fatigue-life (García Páez et al., 2006, 2007; Rojo et al., 2010). Fatigue tests were performed in vitro on 24 pericardium specimens cut in a root-to-apex direction. The specimens were subjected to a maximum stress of 1MPa in blocks of 10, 25, 50, 100, 250, 500, 1000 and 1500 cycles. By means of a modified Shore A hardness test procedure, the hardness of the specimen was measured before and after fatigue tests. Results showed a significant correlation of such hardness with fatigue performance and with the energy dissipated in the first cycle of fatigue, a predictor of pericardium durability. The study showed indentation hardness as a simple and reliable indicator of mechanical performance, one which could be easily implemented in improving tissue selection.
NASA Astrophysics Data System (ADS)
Cai, Bao-Jun; Li, Bao-An
2016-01-01
It is well known that short-range nucleon-nucleon correlations (SRC) from the tensor components and/or the repulsive core of nuclear forces lead to a high- (low-)momentum tail (depletion) in the single-nucleon momentum distribution above (below) the nucleon Fermi surface in cold nucleonic matter. Significant progress was made recently in constraining the isospin-dependent parameters characterizing the SRC-modified single-nucleon momentum distribution in neutron-rich nucleonic matter using both experimental data and microscopic model calculations. Using the constrained single-nucleon momentum distribution in a nonlinear relativistic mean field (RMF) model, we study the equation of state (EOS) of asymmetric nucleonic matter (ANM), especially the density dependence of nuclear symmetry energy Esym(ρ ) . First, as a test of the model, the average nucleon kinetic energy extracted recently from electron-nucleus scattering experiments using a neutron-proton dominance model is well reproduced by the RMF model incorporating effects of the SRC-induced high-momentum nucleons, while it is significantly under predicted by the RMF model using a step function for the single-nucleon momentum distribution as in free Fermi gas (FFG) models. Second, consistent with earlier findings within nonrelativistic models, the kinetic symmetry energy of quasinucleons is found to be Esymkin(ρ0) =-16.94 ±13.66 MeV which is dramatically different from the prediction of Esymkin(ρ0) ≈12.5 MeV by FFG models at nuclear matter saturation density ρ0=0.16 fm-3 . Third, comparing the RMF calculations with and without the high-momentum nucleons using two sets of model parameters both reproducing identically all empirical constraints on the EOS of symmetric nuclear matter (SNM) and the symmetry energy of ANM at ρ0, the SRC-modified single-nucleon momentum distribution is found to make the Esym(ρ ) more concave around ρ0 by softening it significantly at both subsaturation and suprasaturation
IceCube Collaboration; Pierre Auger Collaboration; Telescope Array Collaboration
2016-01-01
This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.
Aartsen, M. G.
2016-01-20
This study presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECRmore » magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.« less
Aartsen, M. G.
2016-01-20
This study presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.
Gautam, R K; Thakur, R
2009-09-01
The paper aims to draw out biosocial correlates of nutrition through body mass index (BMI) and chronic energy deficiency (CED). The findings are based on cross-sectional data of 446 women aged 18-60 years from six different endogamous groups of two ecological zones. The mean age of studied women varied from 31 to 36 years. The mean age at menarche was found to be 14.50±1.32 years. Similarly mean age at menopause was found to be 46.22±4.00 years. The mean of reproductive life span varied from 27 to 35 years. Average number of pregnancies per women was 4.44±2.52, average foetal loss was 0.11, children surviving per women was 3.61, whereas average child loss per women was found to be 0.62 and average family size was 9.51. Variations in mean BMI kg/m2 between populations ranged between 18.56 and 20.71. Prevalence of CED was highest among the Brahmin women of Uttarakhand (58.3%) followed by Ahirwar of Madhya Pradesh (47.1%). Incidence of CED was found lowest among Brahmin women of Madhya Pradesh (24.0%). Linear regression coefficient (b ± standard error) of BMI on Cormic Index for these women was 33.1 ± 8.1 (t=4.0, p=0.001), and correlation coefficient (R) was 0.189. Out of 6 anthropometric variables considered for regression analysis, 5, namely weight, hip circumference, waist circumference, mid arm circumference and sitting height showed significant correlations with BMI. Significant differences in sitting height and Cormic Index of women from the hills and plains indicate the role of ecology in shaping its habitants. Out of 9 demographic variables, only age of respondent and family size were found to have a significant impact on low BMI status. The present study postulates that the nutritional status of women has improved over the last decades.
Weyers, Amanda M; Chatterjee, Ruchira; Milikisiyants, Sergey; Lakshmi, K V
2009-11-19
Quinones are widely used electron transport cofactors in photosynthetic reaction centers. Previous studies have suggested that the structure of the quinone cofactors and the protein interactions or "smart" matrix effects from the surrounding environment govern the redox potential and hence the function of quinones in photosynthesis. In the present study, a series of 1,4-benzoquinone models are examined via differential pulse voltammetry to provide relative redox potentials. In parallel, CW and pulsed EPR methods are used to directly determine the electronic properties of each benzoquinone in aprotic and protic environments. The shifts in the redox potential of the quinones are found to be dependent on the nature of the substituent group and the number of substituent groups on the quinone molecule. Further, we establish a direct correlation between the nature of the substituent group and the change in electronic properties of the benzosemiquinone by analysis of the isotropic and anisotropic components of the electron-nuclear hyperfine interactions observed by CW and pulsed EPR studies, respectively. Examination of an extensive library of model quinones in both aprotic and protic solvents indicates that hydrogen-bonding interactions consistently accentuate the effects of the substituent groups of the benzoquinones. This study provides direct support for the tuning and control of quinone cofactors in biological solar energy transduction through interactions with the surrounding protein matrix.
NASA Astrophysics Data System (ADS)
Ismail, M.; Adel, A.
2014-12-01
The preformation probability of an α cluster inside radioactive parent nuclei is investigated. The calculations are employed in the framework of the density-dependent cluster model for both even-even and odd-A isotopes with 74 ≤Z ≤83 . A realistic density-dependent nucleon-nucleon (N N ) interaction with a finite-range exchange part is used to calculate the microscopic α -nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the α and daughter nuclei has been included in the folding model through the finite-range exchange part of the N N interaction. The calculated potential is then implemented to find both the assault frequency and the penetration probability of the α particle by means of the Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. We investigated the correlation between the α -particle preformation probability, Sα, and the energy levels of the parent nucleus for α emitters with atomic number 74 ≤Z ≤83 . Based on the similarity in the behavior of Sα with the neutron number for two nuclei, we try to predict or confirm the unknown or doubted nuclear spins and parities in this mass region.
Abdurakhmanov, U. U. Gulamov, K. G.; Zhokhova, S. I.; Navotny, V. Sh.
2010-01-15
Inter- and intragroup azimuthal correlations of target and projectile fragments and of shower particles in the interactions between gold nuclei of energy 10.6 GeV per nucleon and silver and bromine nuclei of a track emulsion are studied at intermediate values of the impact parameter. The asymmetry index {beta}'{sub 1} and the collinearity index {beta}'{sub 2} of groups' asymmetry vectors are used to study azimuthal correlations between two and three groups of particles. The interplay of effects of intra- and intergroup azimuthal particle correlations is investigated.
Small Al clusters. I - The effect of basis set and correlation on the geometry of small Al clusters
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.
1987-01-01
A detailed study is presented of the basis set requirements and effects of correlation on the geometry and structure of small Al(n) clusters n = 2, 4, and 13. An effective core potential (ECP) is developed from the Huzinaga basis which accurately reproduces the all-electron results. It is found that depolarization functions are very important in computing the bond length, and that the bond contraction obtained is about as large for a 13-atom cluster as for the Al(4) rhombus structure. With d functions on each center in Al(13), a bond distance shorter than the bulk is obtained, as expected. The inclusion of correlation in Al(4) is found to be less important than the addition of polarization functions for determining the bond length, but increases substantially the calculated atomization energy. These calibration calculations allow an accurate treatment for Al(n) clusters to be designed.
NASA Astrophysics Data System (ADS)
Weigand, Anna; Cao, Xiaoyan; Vallet, Valérie; Flament, Jean-Pierre; Dolg, Michael
2009-07-01
In order to assess the accuracy of a recently adjusted relativistic energy-consistent small-core pseudopotential for uranium, the U5+ (5f1 subconfiguration) spin-orbit splitting as well as the fine structure of the U4+ (5f2 subconfiguration) spectrum have been calculated. The pseudopotential has been adjusted to four-component all-electron data, i.e., at the multiconfiguration Dirac-Hartree-Fock level using the Dirac-Coulomb Hamiltonian with a Fermi nucleus charge distribution and perturbatively including the Breit interaction. Its performance in a dressed effective Hamiltonian spin-orbit configuration interaction framework is compared to that of an older scalar-relativistic Wood-Boring adjusted pseudopotential, supplemented by a valence spin-orbit term, as well as to all-electron calculations using the Douglas-Kroll-Hess Hamiltonian. Electron correlation is accounted for by the multireference configuration interaction method with and without the Davidson correction and with different frozen-orbital spaces. Our best calculations show satisfactory agreement with experimental data; i.e., the mean absolute (relative) deviations amount to 183 (2.4%) and 948 cm-1 (5.1%) for the U5+ and the U4+ fine-structure energy levels, respectively. Even better agreement, comparable to the one for rigorous highly correlated four-component all-electron data, is obtained in intermediate Hamiltonian Fock-space coupled-cluster calculations applying the new pseudopotential.
Optomechanical Quantum Correlation Thermometry
NASA Astrophysics Data System (ADS)
Purdy, T. P.; Grutter, K. E.; Davanco, M. I.; Srinivasan, K.; Taylor, J. M.
We present an optomechanical approach for producing accurate thermometry over a wide temperature range using quantum Brownian motion. Optical measurements induce quantum correlations in an optomechanical system when quantum-limited intensity fluctuations of a probe laser drive mechanical motion. The size of the correlations in the weak probe limit are dictated by the scale of individual phonons. We have recently measured optomechanical quantum correlations in the cross correlation spectrum between the amplitude and phase fluctuations of a single probe laser interacting with a silicon nitride optomechanical crystal. These correlations are independent of thermally-induced Brownian motion. However, Brownian motion does simultaneously produce much larger correlation signals between other optical quadratures. A comparison of the size of thermally-induced correlations to quantum correlations allows us to absolutely calibrate Brownian motion thermometry to the mechanical energy quantization scale.
Martz, Meghan E.; Patrick, Megan E.; Schulenberg, John E.
2015-01-01
Purpose The consumption of alcohol mixed with energy drinks (AmED) is a risky drinking behavior, most commonly studied using college samples. We know little about rates of AmED use and its associations with other risk behaviors, including unsafe driving, among high school students. This study examined the prevalence and correlates of AmED use among high school seniors in the United States. Methods Nationally representative analytic samples included 6,498 12th-grade students who completed Monitoring the Future surveys in 2012 and 2013. Focal measures included AmED use, sociodemographic characteristics, academic and social factors, other substance use, and unsafe driving (i.e., tickets/warnings and accidents) following alcohol consumption. Results Approximately one in four students (24.8%) reported AmED use during the past 12 months. Rates of AmED use were highest among males and White students. Using multivariable logistic regression models controlling for sociodemographic characteristics, results indicate that students who cut class, spent more evenings out for fun and recreation, and reported binge drinking, marijuana use, and illicit drug use had a greater likelihood of AmED use. AmED use was also associated with greater odds of alcohol-related unsafe driving, even after controlling for sociodemographic, academic, and social factors, and other substance use. Conclusions AmED use among 12th-grade students is common and associated with certain sociodemographic, academic, social, and substance use factors. AmED use is also related to alcohol-related unsafe driving, which is a serious public health concern. PMID:25907654
NASA Astrophysics Data System (ADS)
Zheng, Jianghui; Cheng, Qijin; Zheng, Cheng; Chen, Guo; Shi, Feng; Chen, Chao
2015-08-01
NaBa0.97-xBO3 0.03Dy3+, xEu3+(0 ≤ x ≤ 0.09) single-phase white phosphors with tunable correlated color temperature (CCT) were synthesized using a conventional solid state reaction method. The phase structure and luminescence properties of the as-prepared samples were investigated. The Dy3+, Eu3+ doped and Dy3+/Eu3+ co-doped NaBaBO3 phosphors excited by 361 nm show two blue and yellow emissions corresponding to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions and two red emissions due to the 5D0 → 4FJ (J = 1, 2) transitions of Eu3+ ions. Under 361-nm light excitation, the NaBa0.97-xBO3 0.03 Dy3+, xEu3+(0 ≤ x ≤ 0.09) phosphors feature a white light emitting property. Through the Commission Internationale de L'Eclairage (CIE) chromaticity analysis and CCT calculation, the CIE chromaticity coordinates of the emission light are all located in the white region and can be tuned from bluish white light to reddish white light when the Eu3+ concentration increases, and the CCT values of the obtained samples can vary from 5514.31 K to 8269.42 K. Furthermore, the energy transfer phenomenon from Dy3+ ions to Eu3+ ions in Dy3+/Eu3+ co-doped samples was also investigated. The results indicated that, through tuning the Eu3+ concentration of the NaBaBO3:Dy3+/Eu3+ phosphors, the NaBaBO3-based phosphor can act as a potential single-phase white emitting phosphor for the application in the near-ultraviolet (NUV) white light emitting diodes.
Lamiel-Garcia, Oriol; Ko, Kyoung Chul; Lee, Jin Yong; Bromley, Stefan T; Illas, Francesc
2017-03-10
All electron relativistic density functional theory (DFT) based calculations using numerical atom-centered orbitals have been carried out to explore the relative stability, atomic, and electronic structure of a series of stoichiometric TiO2 anatase nanoparticles explicitly containing up to 1365 atoms as a function of size and morphology. The nanoparticles under scrutiny exhibit octahedral or truncated octahedral structures and span the 1-6 nm diameter size range. Initial structures were obtained using the Wulff construction, thus exhibiting the most stable (101) and (001) anatase surfaces. Final structures were obtained from geometry optimization with full relaxation of all structural parameters using both generalized gradient approximation (GGA) and hybrid density functionals. Results show that, for nanoparticles of a similar size, octahedral and truncated octahedral morphologies have comparable energetic stabilities. The electronic structure properties exhibit a clear trend converging to the bulk values as the size of the nanoparticles increases but with a marked influence of the density functional employed. Our results suggest that electronic structure properties, and hence reactivity, for the largest anatase nanoparticles considered in this study will be similar to those exhibited by even larger mesoscale particles or by bulk systems. Finally, we present compelling evidence that anatase nanoparticles become effectively bulklike when reaching a size of ∼20 nm diameter.
NASA Astrophysics Data System (ADS)
Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Benacek, P.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kostarakis, P.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molñar, L.; Montaño Zetina, L.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Pereira da Costa, H.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shahzad, M. I.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; de Souza, R. D.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yang, H.; Yang, P.; Yano, S.; Yasin, Z.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration
2016-05-01
Three- and four-pion Bose-Einstein correlations are presented in p p ,p -Pb, and Pb-Pb collisions at the LHC. We compare our measured four-pion correlations to the expectation derived from two- and three-pion measurements. Such a comparison provides a method to search for coherent pion emission. We also present mixed-charge correlations in order to demonstrate the effectiveness of several analysis procedures such as Coulomb corrections. Same-charge four-pion correlations in p p and p -Pb appear consistent with the expectations from three-pion measurements. However, the presence of non-negligible background correlations in both systems prevent a conclusive statement. In Pb-Pb collisions, we observe a significant suppression of three- and four-pion Bose-Einstein correlations compared to expectations from two-pion measurements. There appears to be no centrality dependence of the suppression within the 0%-50% centrality interval. The origin of the suppression is not clear. However, by postulating either coherent pion emission or large multibody Coulomb effects, the suppression may be explained.
Morrison, Robert C.
2015-01-07
Accurate densities were determined from configuration interaction wave functions for atoms and ions of Li, Be, and B with up to four electrons. Exchange-correlation potentials, V{sub xc}(r), and functional derivatives of the noninteracting kinetic energy, δK[ρ]/δρ(r), obtained from these densities were used to examine their discontinuities as the number of electrons N increases across integer boundaries for N = 1, N = 2, and N = 3. These numerical results are consistent with conclusions that the discontinuities are characterized by a jump in the chemical potential while the shape of V{sub xc}(r) varies continuously as an integer boundary is crossed. The discontinuity of the V{sub xc}(r) is positive, depends on the ionization potential, electron affinity, and orbital energy differences, and the discontinuity in δK[ρ]/δρ(r) depends on the difference between the energies of the highest occupied and lowest unoccupied orbitals. The noninteracting kinetic energy and the exchange correlation energy have been computed for integer and noninteger values of N between 1 and 4.
Morrison, Robert C
2015-01-07
Accurate densities were determined from configuration interaction wave functions for atoms and ions of Li, Be, and B with up to four electrons. Exchange-correlation potentials, Vxc(r), and functional derivatives of the noninteracting kinetic energy, δK[ρ]/δρ(r), obtained from these densities were used to examine their discontinuities as the number of electrons N increases across integer boundaries for N = 1, N = 2, and N = 3. These numerical results are consistent with conclusions that the discontinuities are characterized by a jump in the chemical potential while the shape of Vxc(r) varies continuously as an integer boundary is crossed. The discontinuity of the Vxc(r) is positive, depends on the ionization potential, electron affinity, and orbital energy differences, and the discontinuity in δK[ρ]/δρ(r) depends on the difference between the energies of the highest occupied and lowest unoccupied orbitals. The noninteracting kinetic energy and the exchange correlation energy have been computed for integer and noninteger values of N between 1 and 4.
Dean, M. P. M.; Cao, Y.; Liu, X.; Wall, S.; Zhu, D.; Mankowsky, R.; Thampy, V.; Chen, X. M.; Vale, J. G.; Casa, D.; Kim, Jungho; Said, A. H.; Juhas, P.; Alonso-Mori, R.; Glownia, J. M.; Robert, A.; Robinson, J.; Sikorski, M.; Song, S.; Kozina, M.; Lemke, H.; Patthey, L.; Owada, S.; Katayama, T.; Yabashi, M.; Tanaka, Yoshikazu; Togashi, T.; Liu, J.; Rayan Serrao, C.; Kim, B. J.; Huber, L.; Chang, C. -L.; McMorrow, D. F.; Forst, M.; Hill, J. P.
2016-05-09
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity^{1, 2, 3, 4}. Recently, photo-excitation has been used to induce similarly exotic states transiently^{5, 6, 7}. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr_{2}IrO_{4}. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. In conclusion, the marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.
Dean, M. P. M.; Cao, Y.; Liu, X.; ...
2016-05-09
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity1, 2, 3, 4. Recently, photo-excitation has been used to induce similarly exotic states transiently5, 6, 7. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation,more » exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. In conclusion, the marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.« less
Dean, M P M; Cao, Y; Liu, X; Wall, S; Zhu, D; Mankowsky, R; Thampy, V; Chen, X M; Vale, J G; Casa, D; Kim, Jungho; Said, A H; Juhas, P; Alonso-Mori, R; Glownia, J M; Robert, A; Robinson, J; Sikorski, M; Song, S; Kozina, M; Lemke, H; Patthey, L; Owada, S; Katayama, T; Yabashi, M; Tanaka, Yoshikazu; Togashi, T; Liu, J; Rayan Serrao, C; Kim, B J; Huber, L; Chang, C-L; McMorrow, D F; Först, M; Hill, J P
2016-06-01
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity. Recently, photo-excitation has been used to induce similarly exotic states transiently. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. The marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.
NASA Astrophysics Data System (ADS)
Dean, M. P. M.; Cao, Y.; Liu, X.; Wall, S.; Zhu, D.; Mankowsky, R.; Thampy, V.; Chen, X. M.; Vale, J. G.; Casa, D.; Kim, Jungho; Said, A. H.; Juhas, P.; Alonso-Mori, R.; Glownia, J. M.; Robert, A.; Robinson, J.; Sikorski, M.; Song, S.; Kozina, M.; Lemke, H.; Patthey, L.; Owada, S.; Katayama, T.; Yabashi, M.; Tanaka, Yoshikazu; Togashi, T.; Liu, J.; Rayan Serrao, C.; Kim, B. J.; Huber, L.; Chang, C.-L.; McMorrow, D. F.; Först, M.; Hill, J. P.
2016-06-01
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity. Recently, photo-excitation has been used to induce similarly exotic states transiently. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. The marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.
Accurate nonrelativistic ground-state energies of 3d transition metal atoms
Scemama, A.; Applencourt, T.; Giner, E.; Caffarel, M.
2014-12-28
We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including the most prominent determinants of the full configuration interaction expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. To the best of our knowledge, the FN-DMC/(CIPSI nodes) ground-state energies presented here are the lowest variational total energies reported so far. They differ from the recently recommended non-variational values of McCarthy and Thakkar [J. Chem. Phys. 136, 054107 (2012)] only by a few percents of the correlation energy. Thanks to the variational property of FN-DMC total energies, our results provide exact lower bounds for the absolute value of all-electron correlation energies, |E{sub c}|.
Conforti, Patrick F.; Prasad, Manish; Garrison, Barbara J.
2008-05-15
The energetics initiating ablation in poly(methyl methacrylate) (PMMA) are studied using molecular dynamics (MD) simulation. The critical energy to initiate ablation in PMMA following the absorption of photons is investigated for two penetration depths along a range of fluences using a coarse-grained, hybrid Monte Carlo-MD scheme. Both heating and direct bond scission are simulated separately after photon absorption with additional transformation of material occurring via chemical reactions following the photochemical bond cleavage. For a given type of absorption and reaction channel, a critical energy can well describe the amount of energy required to initiate ablation. The simulations show a decrease in the critical energy when a greater amount of photochemistry is introduced in the system. The simulations complement experimental studies and elucidate how enhanced photochemistry lowers ablation thresholds in polymer substrates.
NASA Technical Reports Server (NTRS)
Cotariu, Steven S.
1991-01-01
Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.
2016-03-18
In this paper, we present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au + Au collisions for energies ranging from √sNN = 7.7 to 200 GeV. The third harmonic v$2\\atop{3}${ 2 } =
Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing
2016-03-23
Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.
NASA Astrophysics Data System (ADS)
Sordillo, Laura A.; Sordillo, Peter P.; Budansky, Yury; Pu, Yang; Alfano, Robert R.
2014-12-01
The correlation between histologic grade, an increasingly important measure of prognosis for patients with breast cancer, and tryptophan levels from tissues of 15 breast carcinoma patients was investigated. Changes in the relative content of key native organic biomolecule tryptophan were seen from the fluorescence spectra of cancerous and paired normal tissues with excitation wavelengths of 280 and 300 nm. Due to a large spectral overlap and matching excitation-emission spectra, fluorescence resonance energy transfer from tryptophan-donor to reduced nicotinamide adenine dinucleotides-acceptor was noted. We used the ratios of fluorescence intensities at their spectral emission peaks, or spectral fingerprint peaks, at 340, 440, and 460 nm. Higher ratios correlated strongly with high histologic grade, while lower-grade tumors had low ratios. Large tumor size also correlated with high ratios, while the number of lymph node metastases, a major factor in staging, was not correlated with tryptophan levels. High histologic grade correlates strongly with increased content of tryptophan in breast cancer tissues and suggests that measurement of tryptophan content may be useful as a part of the evaluation of these patients.
Geremew, Kumlachew; Gedefaw, Molla; Dagnew, Zewdu; Jara, Dube
2014-01-01
Background. Traditional biomass has been the major source of cooking energy for major segment of Ethiopian population for thousands of years. Cognizant of this energy poverty, the Government of Ethiopia has been spending huge sum of money to increase hydroelectric power generating stations. Objective. To assess current levels and correlates of traditional cooking energy sources utilization. Methods. A community based cross-sectional study was conducted employing both quantitative and qualitative approaches on systematically selected 423 households for quantitative and purposively selected 20 people for qualitative parts. SPSS version 16 for windows was used to analyze the quantitative data. Logistic regression was fitted to assess possible associations and its strength was measured using odds ratio at 95% CI. Qualitative data were analyzed thematically. Result. The study indicated that 95% of households still use traditional biomass for cooking. Those who were less knowledgeable about negative health and environmental effects of traditional cooking energy sources were seven and six times more likely to utilize them compared with those who were knowledgeable (AOR (95% CI) = 7.56 (1.635, 34.926), AOR (95% CI) = 6.68 (1.80, 24.385), resp.). The most outstanding finding of this study was that people use traditional energy for cooking mainly due to lack of the knowledge and their beliefs about food prepared using traditional energy. That means “…people still believe that food cooked with charcoal is believed to taste delicious than cooked with other means.” Conclusion. The majority of households use traditional biomass for cooking due to lack of knowledge and belief. Therefore, mechanisms should be designed to promote electric energy and to teach the public about health effects of traditional cooking energy source. PMID:24895591
NASA Technical Reports Server (NTRS)
Vlahopoulos, Nickolas
2005-01-01
The Energy Finite Element Analysis (EFEA) is a finite element based computational method for high frequency vibration and acoustic analysis. The EFEA solves with finite elements governing differential equations for energy variables. These equations are developed from wave equations. Recently, an EFEA method for computing high frequency vibration of structures either in vacuum or in contact with a dense fluid has been presented. The presence of fluid loading has been considered through added mass and radiation damping. The EFEA developments were validated by comparing EFEA results to solutions obtained by very dense conventional finite element models and solutions from classical techniques such as statistical energy analysis (SEA) and the modal decomposition method for bodies of revolution. EFEA results have also been compared favorably with test data for the vibration and the radiated noise generated by a large scale submersible vehicle. The primary variable in EFEA is defined as the time averaged over a period and space averaged over a wavelength energy density. A joint matrix computed from the power transmission coefficients is utilized for coupling the energy density variables across any discontinuities, such as change of plate thickness, plate/stiffener junctions etc. When considering the high frequency vibration of a periodically stiffened plate or cylinder, the flexural wavelength is smaller than the interval length between two periodic stiffeners, therefore the stiffener stiffness can not be smeared by computing an equivalent rigidity for the plate or cylinder. The periodic stiffeners must be regarded as coupling components between periodic units. In this paper, Periodic Structure (PS) theory is utilized for computing the coupling joint matrix and for accounting for the periodicity characteristics.
Fontaine, G; Aldakar, M; Iwa, T; Grosgogeat, Y
1990-10-01
Using the same methods as for the measurement of electrical parameters by means of an oscilloscope with a wave shape calculator to determine at all points the energy and impedance values, as well as high speed cinematography, the analysis of the behavior of these parameters for shocks with energies close to those used in clinical medicine can be carried out. It shows namely an important decrease in the impedance at the current peak due to an important ionization of the fulguration bubble. It underlines the different behavior of the anode and cathode bubbles, in relation with the size of the bubbles obtained thanks to rapid cinematography. Comparative measurements concerning the polarity, the size of the indifferent electrode, the medium used in vitro and in vivo have supplied the elements to enable the precise determination of the adequate electrical parameters for the good use of fulguration.
Hafez, Ahmed M; Salem, Noha M; Allam, Nageh K
2014-09-14
We report on the first principles calculation of the electronic, structural and optical properties of BaTaO2N, using density functional theory (DFT) and finite difference time domain (FDTD) methods. Band structure calculations were performed to calculate the direct and indirect bandgaps of the material. Density of states and Mulliken charge analysis as well as the electronic contour maps were established to determine the type of bonding and hybridization between the various electronic states. The dielectric constant, reflectivity, absorption, optical conductivity and energy-loss function were also calculated. Moreover, FDTD was used to investigate the optical properties of a larger and more reliable structure of BaTaO2N powder in good agreement with the reported experimental parameters. The calculated electronic, structural and optical properties showed the potential of BaTaO2N for solar energy conversion and optoelectronic applications.
Liu, L.; Magini, M.
1997-09-01
Phase transformations of Mo{sub 33}Si{sub 66} powder mixture under different milling conditions have been systematically investigated by x-ray diffraction, scanning and transmission electron microscopy. The effect of the milling conditions on the Mo/Si solid state reactions (SSR) has been examined in detail. The energy transfer from the milling tools to the powder under processing has been quantified by an already assessed collision model. It has been found that the higher energetic input favors the formation of the room temperature stable phase {alpha}MoSi{sub 2}, while the lower energetic input promotes the formation of the metastable phase {beta}MoSi{sub 2}. In addition, if the energy transfer is high enough, the Mo/Si reaction proceeds in a form of self-propagating high temperature synthesis (SHS). Thermodynamics and kinetics aspects related to the different SSRs have been discussed. {copyright} {ital 1997 Materials Research Society.}
Roig, Andres I.; Hight, Suzie K.; Minna, John D.; Shay, Jerry W.; Rusek, Adam; Story, Michael D.
2012-01-01
Purpose The DNA double-strand break (DSB) damage response induced by high energy charged particles on lung fibroblast cells embedded in a 3-dimensional (3-D) collagen tissue equivalents was investigated using antibodies to the DNA damage response proteins gamma-histone 2AX (γ-H2AX) and phosphorylated DNA-PKcs (p-DNA-PKcs). Materials and methods 3-D tissue equivalents were irradiated in positions across the linear distribution of the Bragg curve profiles of 307.7 MeV/nucleon, 556.9 MeV/nucleon, or 967.0 MeV/nucleon 56Fe ions at a dose of 0.30 Gy. Results Patterns of discrete DNA damage streaks across nuclei or saturated nuclear damage were observed, with saturated nuclear damage being more predominant as samples were positioned closer to the physical Bragg peak. Quantification of the DNA damage signal intensities at each distance for each of the examined energies revealed a biological Bragg curve profile with a pattern of DNA damage intensity similar to the physical Bragg curve for the particular energy. Deconvolution microscopy of nuclei with streaked or saturated nuclear damage pattern revealed more details of the damage, with evidence of double-strand breaks radially distributed from the main particle track as well as multiple discrete tracks within saturated damage nuclei. Conclusions These 3-D culture systems can be used as a biological substrate to better understand the interaction of heavy charged particles of different energies with tissue and could serve as a basis to model space-radiation-induced cancer initiation and progression. PMID:20201648
Chatrchyan, Serguei; et al.
2011-07-01
First measurements of dihadron correlations for charged particles are presented for central PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV over a broad range in relative pseudorapidity, Delta(eta), and the full range of relative azimuthal angle, Delta(phi). The data were collected with the CMS detector, at the LHC. A broadening of the away-side (Delta(phi) approximately pi) azimuthal correlation is observed at all Delta(eta), as compared to the measurements in pp collisions. Furthermore, long-range dihadron correlations in Delta(eta) are observed for particles with similar phi values. This phenomenon, also known as the "ridge", persists up to at least |Delta(eta)| = 4. For particles with transverse momenta (pt) of 2-4 GeV/c, the ridge is found to be most prominent when these particles are correlated with particles of pt = 2-6 GeV/c, and to be much reduced when paired with particles of pt = 10-12 GeV/c.
Adare, A; Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Al-Jamel, A; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Asai, J; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baksay, G; Baksay, L; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bickley, A A; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Campbell, S; Chai, J-S; Chand, P; Chang, B S; Chang, W C; Charvet, J-L; Chernichenko, S; Chiba, J; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Chujo, T; Chung, P; Churyn, A; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Constantin, P; Csanád, M; Csörgo, T; Cussonneau, J P; Dahms, T; Das, K; David, G; Deák, F; Deaton, M B; Dehmelt, K; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Dion, A; Donadelli, M; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Ellinghaus, F; Emam, W S; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Eyser, K O; Fields, D E; Finck, C; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Forestier, B; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fung, S-Y; Fusayasu, T; Gadrat, S; Garishvili, I; Gastineau, F; Germain, M; Glenn, A; Gong, H; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-A; Hachiya, T; Hadj Henni, A; Haegemann, C; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Han, R; Hansen, A G; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; Heffner, M; Hemmick, T K; Hester, T; Heuser, J M; He, X; Hidas, P; Hiejima, H; Hill, J C; Hobbs, R; Hohlmann, M; Holmes, M; Holzmann, W; Homma, K; Hong, B; Hoover, A; Horaguchi, T; Hornback, D; Hur, M G; Ichihara, T; Ikonnikov, V V; Imai, K; Inaba, M; Inoue, Y; Inuzuka, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kaneta, M; Kang, J H; Kanou, H; Katou, K; Kawabata, T; Kawagishi, T; Kawall, D; Kazantsev, A V; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, E; Kim, G-B; Kim, H J; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klay, J; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Kohara, R; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kroon, P J; Kubart, J; Kuberg, C H; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y-S; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Lee, T; Leitch, M J; Leite, M A L; Lenzi, B; Lim, H; Liska, T; Litvinenko, A; Liu, M X; Li, X; Li, X H; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mao, Y; Martinez, G; Masek, L; Masui, H; Matathias, F; Matsumoto, T; McCain, M C; McCumber, M; McGaughey, P L; Miake, Y; Mikes, P; Miki, K; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mishra, M; Mitchell, J T; Mitrovski, M; Mohanty, A K; Morreale, A; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Oda, S X; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, H; Okada, K; Oka, M; Omiwade, O O; Oskarsson, A; Otterlund, I; Ouchida, M; Oyama, K; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Penev, V; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pierson, A; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qualls, J M; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Sakata, H; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Seele, J; Seidl, R; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shevel, A; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Slunecka, M; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Toia, A; Tojo, J; Tomásek, L; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Uam, T J; Vale, C; Valle, H; vanHecke, H W; Velkovska, J; Velkovsky, M; Vertesi, R; Veszprémi, V; Vinogradov, A A; Virius, M; Volkov, M A; Vrba, V; Vznuzdaev, E; Wagner, M; Walker, D; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Wohn, F K; Woody, C L; Wysocki, M; Xie, W; Yamaguchi, Y L; Yanovich, A; Yasin, Z; Ying, J; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zhou, S; Zimányi, J; Zolin, L; Zong, X
2007-06-08
We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at square root sNN=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
NASA Astrophysics Data System (ADS)
Roberts, Peter M.
The purpose of this study was to examine white noise effects of U.S. crude oil spot prices on the stock prices of a green energy company. Epistemological, Phenomenological, Axiological and Ontological assumptions of Green Energy Management (GEM) Theory were utilized for selecting Air Products and Chemicals Inc. (APD) as the case study. Exxon Mobil (XOM) was used as a control for triangulation purposes. The period of time examined was between January of 1999 and December of 2008. Monthly stock prices for APD and XOM for the ten year period of time were collected from the New York Stock Exchange. Monthly U.S. crude oil spot prices for the ten year period of time were collected from the US Energy Information Administration. The data was entered into SPSS 17.0 software in order to conduct cross-correlation analysis. The six cross-correlation assumptions were satisfied in order to conduct a Cross-correlation Mirror Test (CCMT). The CCMT established the lag time direction and verified that U.S. crude oil spot prices serve as white noise for stock prices of APD and XOM. The Theory of Relative Weakness was employed in order to analyze the results. A 2 year period of time between December, 2006 and December, 2008 was examined. The correlation coefficient r = - .155 indicates that U.S. crude oil spot prices lead APD stock prices by 4 months. During the same 2 year period of time, U.S. crude oil spot prices lead XOM stock prices by 4 months at r = -.283. XOM stock prices and APD stock prices were positively correlated with 0 lag in time with a positive r = .566. The 4 month cycle was an exact match between APD stock prices, XOM stock prices and U.S. crude oil spot prices. The 4 month cycle was due to the random price fluctuation of U.S. crude oil spot prices that obscured the true stock prices of APD and XOM for the 2 year period of time.
Siderius, Daniel W; Gelb, Lev D
2009-08-28
Using both molecular simulation and theory, we examine fluid-phase thermodynamic and structural properties of on-lattice hard-sphere fluids. Our purpose in this work is to provide reference data for on-lattice density functional theories [D. W. Siderius and L. D. Gelb, Langmuir 25, 1296 (2009)] and related perturbation theories. In this model, hard spheres are located at sites on a finely discretized cubic lattice where the spacing between lattice sites is between one-tenth and one-third the hard-sphere diameter. We calculate exactly the second, third, and fourth virial coefficients as functions of the lattice spacing. Via Monte Carlo simulation, we measure the excess chemical potential as a function of density for several lattice spacings. These results are then parametrized with a convenient functional form and can immediately be used in on-lattice density functional theories. Of particular interest is to identify those lattice spacings that yield properties similar to those of the off-lattice fluid. We find that the properties of the on-lattice fluid are strongly dependent on lattice spacing, generally approaching those of the off-lattice fluid with increasing lattice resolution, but not smoothly. These observations are consistent with results for larger lattice spacings [A. Z. Panagiotopoulos, J. Chem. Phys. 123, 104504 (2005)]. Certain lattice spacings are found to yield fluid properties in particularly good agreement with the off-lattice fluid. We also find that the agreement of many different on- and off-lattice hard-sphere fluid properties is predicted quite well by that of the virial coefficients, suggesting that they may be used to identify favorable lattice spacings. The direct correlation function at a few lattice spacings and a single density is obtained from simulation. The on-lattice fluid is structurally anisotropic, exhibiting spherical asymmetry in correlation functions. Interestingly, the anisotropies are properly captured in the Percus
Ramdhave, Anup S; Ojha, Shreesh; Nandave, Mukesh
2017-01-01
Emerging evidence suggests that, dysregulation of fatty acid synthase (FASN) and insulin-like growth factor-1 (IGF-1) could play a vital role in pathology of various diseases. Our aim was to determine the changes in FASN and IGF-1 levels concomitant to long term feeding of HFD in either sex. Male and female mice were fed either HFD or LFD for a period of 16 weeks. During this period, physiological, biochemical, and histological parameters were evaluated. Mice fed with HFD showed a significant gain in body weight, body mass index, energy intake, and abdominal circumference. These changes were accompanied by compromised glucose and insulin tolerance, hyperinsulinemia, dyslipidemia, elevated plasma IL-6, and TNF-α concentration. Histologically, hepatocytes showed an elevated fat accumulation, appended by an increase in plasma activities of liver enzymes. Pancreas showed upsurge in number of β-cells with subsequent increase in size of islet implying its compromised state. While the kidney showed mild tubulointerstitial fibrosis indicating initiation of kidney impairment. These metabolic perturbations were related to the energy intake which was higher in males as compared to females. This led to a proportional rise in plasma as well as liver FASN and IGF-1 in HFD fed mice. Within both sexes, mice fed with HFD developed features of non-alcoholic steatohepatitis (NASH), hyperinsulinemia, dyslipidemia, impaired glucose and insulin tolerance but the magnitude of these abnormalities was found to be less in female mice. This variation in magnitude could be attributed to the difference in energy intake and ultimately its effect on FASN and IGF-1 levels. PMID:28386316
Gazder, Azdiar A; Al-Harbi, Fayez; Spanke, Hendrik Th; Mitchell, David R G; Pereloma, Elena V
2014-12-01
Using a combination of electron back-scattering diffraction and energy dispersive X-ray spectroscopy data, a segmentation procedure was developed to comprehensively distinguish austenite, martensite, polygonal ferrite, ferrite in granular bainite and bainitic ferrite laths in a thermo-mechanically processed low-Si, high-Al transformation-induced plasticity steel. The efficacy of the ferrite morphologies segmentation procedure was verified by transmission electron microscopy. The variation in carbon content between the ferrite in granular bainite and bainitic ferrite laths was explained on the basis of carbon partitioning during their growth.
NASA Astrophysics Data System (ADS)
Tsyganov, Yu. S.
2015-07-01
A new real-time PC based algorithm and a compact C++ code to operate in a real-time mode with a 48 × 128 strip double side position sensitive large area silicon radiation detector Micron Semiconductors (UK) are developed and tested. Namely with this new approach it has become possible to provide the quick extraction of EVR-alpha correlated sequences in heavy ion induced complete fusion nuclear reactions. Specific attention is paid to the application of new CAMAC 4 M modules for charge particle position measurement during long-term experiments aimed to the synthesis of new superheavy nuclei. Some attention is paid to the different (combined) algorithm scenario to search for ER-alpha and alpha-alpha chains.
Wang, Yi; Wu, Dapeng; Fu, Li-Min; Ai, Xi-Cheng; Xu, Dongsheng; Zhang, Jian-Ping
2015-07-20
The energy and spatial distribution of intragap trap states of the TiO2 photoanode of dye-sensitized solar cells and their impact on charge recombination were investigated by means of time-resolved charge extraction (TRCE) and transient photovoltage (TPV). The photoanodes were built from TiO2 nanospheroids with different aspect ratios, and the TRCE results allowed differentiation of two different types of trap states, that is, deep and shallow ones at the surface and in the bulk of the TiO2 particles, respectively. These trap states exhibit distinctly different characteristic energy with only a slight variation in the particle size, as derived from the results of the density of states. Analyses of the size-dependent TPV kinetics revealed that in a moderate photovoltage regime of about 375-625 mV, the dynamics of electron recombination are dominated by shallow trap states in the bulk, which can be well accounted for by the mechanism of multiple-trap-limited charge transport.
Galvão, B R L; Varandas, A J C
2009-12-31
A new global potential energy surface is reported for the (4)A'' ground electronic state of the N(3) system from double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. It shows three equivalent metastable potential wells for C(2v) geometries that are separated from the three N((4)S) + N(2) asymptotes by energy barriers as predicted from previous ab initio work. The potential well and barrier height now predicted lie 42.9 and 45.9 kcal mol(-1) above the atom-diatom dissociation limit, respectively, being about 1 kcal mol(-1) lower than previous theoretical estimates. The ab initio calculations here reported predict also a (4)B(1)/(4)A(2) conical intersection and reveal a new minimum with D(3h) symmetry that lies 147 kcal mol(-1) above the atom-diatom asymptote. All major topographical features of the potential energy surface are accurately described by the DMBE function, including the weakly bound van der Waals minima at large atom-diatom separations.
NASA Astrophysics Data System (ADS)
Udhayabanu, V.; Ravi, K. R.; Murty, B. S.
2016-10-01
In the present study, Fe-10 vol pct Al2O3 in situ nanocomposite has been derived by high-energy ball milling of Fe2O3-Fe-Al powder mixture followed by the consolidation using spark plasma sintering (SPS). The consolidated nanocomposite has bimodal-grained structure consisting of nanometer- and submicron-sized Fe grains along with nanometer-sized Al2O3, and Fe3O4 particles. The mechanical property analysis reveals that compressive yield strength of Fe-10 vol pct Al2O3 nanocomposite is 2100 MPa which is nearly two times higher than that of monolithic Fe processed by Mechanical Milling and SPS. The strengthening contributions obtained from matrix, grain size, and particles in the synthesized nanocomposite have been calculated theoretically, and are found to be matching well with the experimental strength levels.
NASA Technical Reports Server (NTRS)
Lynch, Gillian C.; Steckler, Rozeanne; Varandas, Antonio J. C.; Truhlar, Donald G.; Schwenke, David W.
1991-01-01
New ab initio results and a double many-body expansion formalism have been used to parameterize a new FH2 potential energy surface with improved properties near the saddle point and in the region of long-range attraction. The functional form of the new surface includes dispersion forces by a double many-body expansion. Stationary point properties for the new surface are calculated along with the product-valley barrier maxima of vibrationally adiabatic potential curves for F + H2 - HF(nu-prime = 3) + H, F + HD - HF(nu-prime = 3) + D, and F + D2 - DF(nu-prime = 4) + D. The new surface should prove useful for studying the effect on dynamics of a low, early barrier with a wide, flat bend potential.
NASA Astrophysics Data System (ADS)
Karton, Amir; Martin, Jan M. L.
2012-10-01
Accurate isomerization energies are obtained for a set of 45 C8H8 isomers by means of the high-level, ab initio W1-F12 thermochemical protocol. The 45 isomers involve a range of hydrocarbon functional groups, including (linear and cyclic) polyacetylene, polyyne, and cumulene moieties, as well as aromatic, anti-aromatic, and highly-strained rings. Performance of a variety of DFT functionals for the isomerization energies is evaluated. This proves to be a challenging test: only six of the 56 tested functionals attain root mean square deviations (RMSDs) below 3 kcal mol-1 (the performance of MP2), namely: 2.9 (B972-D), 2.8 (PW6B95), 2.7 (B3PW91-D), 2.2 (PWPB95-D3), 2.1 (ωB97X-D), and 1.2 (DSD-PBEP86) kcal mol-1. Isomers involving highly-strained fused rings or long cumulenic chains provide a 'torture test' for most functionals. Finally, we evaluate the performance of composite procedures (e.g. G4, G4(MP2), CBS-QB3, and CBS-APNO), as well as that of standard ab initio procedures (e.g. MP2, SCS-MP2, MP4, CCSD, and SCS-CCSD). Both connected triples and post-MP4 singles and doubles are important for accurate results. SCS-MP2 actually outperforms MP4(SDQ) for this problem, while SCS-MP3 yields similar performance as CCSD and slightly bests MP4. All the tested empirical composite procedures show excellent performance with RMSDs below 1 kcal mol-1.
Coates, Christopher S; Ziegler, Jessica; Manz, Katherine; Good, Jacob; Kang, Bernard; Milikisiyants, Sergey; Chatterjee, Ruchira; Hao, Sijie; Golbeck, John H; Lakshmi, K V
2013-06-20
Quinones function as electron transport cofactors in photosynthesis and cellular respiration. The versatility and functional diversity of quinones is primarily due to the diverse midpoint potentials that are tuned by the substituent effects and interactions with surrounding amino acid residues in the binding site in the protein. In the present study, a library of substituted 1,4-naphthoquinones are analyzed by cyclic voltammetry in both protic and aprotic solvents to determine effects of substituent groups and hydrogen bonds on the midpoint potential. We use continuous-wave electron paramagnetic resonance (EPR) spectroscopy to determine the influence of substituent groups on the electronic properties of the 1,4-naphthoquinone models in an aprotic solvent. The results establish a correlation between the presence of substituent group(s) and the modification of electronic properties and a corresponding shift in the midpoint potential of the naphthoquinone models. Further, we use pulsed EPR spectroscopy to determine the effect of substituent groups on the strength and planarity of the hydrogen bonds of naphthoquinone models in a protic solvent. This study provides support for the tuning of the electronic properties of quinone cofactors by the influence of substituent groups and hydrogen bonding interactions.