Non-interacting Component Research Articles

Efficient reliability analysis with a CDA-based dimension-reduction model and polynomial chaos expansion

Polynomial chaos expansion (PCE) is a versatile tool for building a meta-model in various engineering fields. Unfortunately, it is largely affected by the curse of dimensionality and its application for reliability analysis is usually hindered unless high truncated degrees are used. To alleviate this problem, this paper presents a new method based on contribution-degree analysis (CDA), an exact dimension-reduction model (DRM) and polynomial chaos expansion for efficient reliability analysis. First, the original performance function is decomposed as a summation of several component functions including one lower-dimensional interacting component function and several one-dimensional non-interacting component functions via a CDA-based DRM. Then, the full PCE or sparse PCE is employed to reconstruct the lower-dimensional interacting component function instead of the original complicated multi-dimensional performance function, whereas one-dimensional full PCEs are utilized for approximating the non-interacting component functions. In this way, we avoid building a PCE meta-model for the original multivariate performance function, thus the number of unknown coefficients is significantly reduced and the computational burden for reliability analysis is eased accordingly. Pertinent examples including both analytical performance functions and finite-element models are investigated, which demonstrates that the proposed method achieves a good trade-off of efficiency and accuracy for reliability analysis.

Fully relativistic treatment of decaying cold dark matter in N-body simulations

We present N-body simulations in which either all, or a fraction of, the cold dark matter decays non-relativistically to a relativistic, non-interacting dark radiation component. All effects from radiation and general relativity are self-consistently included at the level of linear perturbation theory, and our simulation results therefore match those from linear Einstein-Boltzmann codes such as {\\sc class} in the appropriate large-scale limit. We also find that standard, Newtonian N-body simulations adequately describe the non-linear evolution at smaller scales (k ≳ 0.1 h/Mpc) in this type of model, provided that the mass of the decaying component is modified correctly, and that the background evolution is correctly treated. That is, for studies of small scales, effects from general relativity and radiation can be safely neglected.

Simulations of galaxy cluster collisions with a dark plasma component

Dark plasma is an intriguing form of self-interacting dark matter with an effective fluid-like behavior, which is well motivated by various theoretical particle physics models. We aim to find an explanation for an isolated mass clump in the Abell 520 system, which cannot be explained by traditional models of dark matter, but has been detected in weak lensing observations. We performed N-body smoothed particle hydrodynamics simulations of galaxy cluster collisions with a two component model of dark matter, which is assumed to consist of a predominant non-interacting dark matter component and a 10-40 percent mass fraction of dark plasma. The mass of a possible dark clump was calculated for each simulation in a parameter scan over the underlying model parameters. In two higher resolution simulations shock-waves and Mach cones were observed to form in the dark plasma halos. By choosing suitable simulation parameters, the observed distributions of dark matter in both the Bullet Cluster (1E 0657-558) and Abell 520 (MS 0451.5+0250) can be qualitatively reproduced.

Exotic superfluidity and pairing phenomena in atomic Fermi gases in mixed dimensions

Atomic Fermi gases have been an ideal platform for simulating conventional and engineering exotic physical systems owing to their multiple tunable control parameters. Here we investigate the effects of mixed dimensionality on the superfluid and pairing phenomena of a two-component ultracold atomic Fermi gas with a short-range pairing interaction, while one component is confined on a one-dimensional (1D) optical lattice whereas the other is in a homogeneous 3D continuum. We study the phase diagram and the pseudogap phenomena throughout the entire BCS-BEC crossover, using a pairing fluctuation theory. We find that the effective dimensionality of the non-interacting lattice component can evolve from quasi-3D to quasi-1D, leading to strong Fermi surface mismatch. Upon pairing, the system becomes effectively quasi-two dimensional in the BEC regime. The behavior of Tc bears similarity to that of a regular 3D population imbalanced Fermi gas, but with a more drastic departure from the regular 3D balanced case, featuring both intermediate temperature superfluidity and possible pair density wave ground state. Unlike a simple 1D optical lattice case, Tc in the mixed dimensions has a constant BEC asymptote.

Communication: Kohn-Sham theory for excited states of Coulomb systems.

For obtaining individual excited-state energies and densities of Coulomb electronic systems, by means of an energy stationary principle, it was shown previously that there exists a universal functional of the density, F(Coul)[ϱ], for the kinetic plus electron-electron repulsion part of the total energy. Here, we make knowledge of the existence of F(Coul)[ϱ] practical for calculation by identifying Ts (Coul)[ϱ], the non-interacting kinetic energy component of F(Coul)[ϱ], and by showing that Ts (Coul)[ϱ] may be computed exactly by means of orbitals that are obtained through a set of single-particle Kohn-Sham equations. Constraints for obtaining accurate approximations to the remaining unknown component of F(Coul)[ϱ] are presented.

Faster photoinduced electron transfer in a diluted mixture than in a neat donor solvent: effect of excited-state H-bonding

In a neat electron-donating solvent (in this case aniline), photoinduced electron transfer (PET) from the solvent to an excited acceptor (e.g. a coumarin fluorophore) may be anticipated to be the most efficient because of the close contact of the acceptor with many donors. Addition of an inert component would most likely retard the PET process by replacing some donors from the neighbourhood of the acceptors. Surprisingly, we found dramatic acceleration of PET (6-10 fold enhancement compared to neat aniline), for coumarin 102 (C102) dissolved in a binary mixture of aniline and an inert solvent (cyclohexane or toluene). The PET induced fluorescence follows an anomalous trend against the mole fraction of aniline (XAN); first quenches up to certain XAN (0.075 for cyclohexane; 0.13 for toluene), thereafter, enhances with increase in XAN. Although the non-interacting component cannot directly participate in the PET process, it may modulate C102-aniline H-bonding association by changing the polarity of the medium or by disrupting the aniline-aniline H-bond. The study clearly illustrates the dominant role of hydrogen bonding in activating the electron transfer rate where standard thermodynamics predicts very weak donor-acceptor interaction.

Modified holographic Ricci dark energy coupled to interacting dark matter and a non-interacting baryonic component

We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component.The estimations of the cosmic parameters with Hubble data lead to an age of the universe of $13.17 {\rm Gyr}$ and show that the MHRDE is free from the cosmic-age problem at low redshift ($0 \leq z \leq 2$) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non interacting baryonic matter forces that the amount of dark energy at $z_{t} \sim {\cal O}(1)$ changes abruptly implying that $\Omega_x (z\simeq 1100) =0.03$, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also obtain that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of $\Omega_x $ at the big bang nucleosynthesis era does not disturb the observed Helium abundance in the universe provided that the bound $\Omega_{x}(z\simeq 10^{10})<0.21$ is hold.

Interacting dark matter and modified holographic Ricci dark energy plus a noninteracting cosmic component

We investigate a spatially flat Friedmann-Robertson-Walker universe that has an interacting dark matter, a modified holographic Ricci dark energy (MHRDE), plus a third, decoupled component that behaves as a radiation term. We consider a nonlinear interaction in the dark component densities and their derivatives up to second order. We apply the $\chi^{2}$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for both MHRDE and holographic Ricci dark energy models. The former is consistent with the bound $\Omega_{x}(z\simeq 1100)<0.1$ reported for the behavior of dark energy at early times while the latter does not fulfill it.

Transport of 125I−, 137Cs+ and 85Sr2+ in granitoidic rock and soil columns

Transport of 125I−, 137Cs+ and 85Sr2+ radionuclides in crushed granitoidic rocks and homogenized soils was studied. Two simple methods for calculation of breakthrough curves in flow column experiments with groundwater as transport medium have been described. The first method, so called non-linear approach, is derived on the assumption of a reversible non-linear sorption isotherm described with Freundlich equation, i.e., with non-constant distribution and retardation coefficients. The second method, so-called linear approach, is applied for reference only, and is based on the assumption of a reversible sorption characterized with linear sorption isotherm, i.e., with constant distribution and retardation coefficients. Both methods model the experimental breakthrough curves with the integrated form of the simple 1-D advection–dispersion equation (ADE) expressed analytically for pulse application of radiotracer to the liquid phase before entering the columns. The integrated form of the ADE equation was modified by the so-called peak position and peak height correction coefficients the advantage of which consists among others in the elimination of the influence of starting concentration. The comparison of both approaches has shown that fitting by means of non-linear approach has given rather reliable values of the transport parameters and calculated dependences, especially in a case of 137Cs system characterized evidently with non-linear type of sorption isotherms. As for 125I−, the sorption capacity of all solid samples studied is nearly on the zero level and 125I− is practically not retarded, and from this point of view it behaves as non-interacting component. In addition, it was found that the modified ADE gives rather better results than the classical one.

Magnetostatic interactions in deep‐sea sediments inferred from first‐order reversal curve diagrams: Implications for relative paleointensity normalization

Understanding magnetostatic interactions in sediments is important for paleomagnetism and rock magnetism. Magnetostatic interactions are known to affect significantly the efficiency of anhysteretic remanent magnetization (ARM) acquisition, and hence the ratio of ARM susceptibility (χARM) to saturation isothermal remanent magnetization (SIRM), a magnetic grain‐size proxy widely used for environmental applications, can be controlled by magnetostatic interactions. Relative paleointensity estimations may also be influenced by magnetostatic interactions because ARM is often used as a normalizer to correct for the difference in magnetizability of sediments. In this study, characterization of magnetic grains in deep‐sea sediments from the North Pacific Ocean was conducted using first‐order reversal curve (FORC) diagrams and IRM acquisition curves. The FORC diagrams indicate that the magnetic grains consist mainly of a noninteracting single‐domain (SD) component and an interacting SD component, and additionally of a multidomain (MD) component. The relative abundances of these components were semiquantitatively estimated by curve fitting of cross sections along a line parallel to the axis of local interaction fields (Hu) and through a peak in the coercivity (Hc). Three components were fitted assuming a Gaussian distribution of interaction fields (Hu). The IRM acquisition curves can be described by two dominant components assuming a log‐Gaussian distribution. The mean coercivities of the two components are ∼40 and ∼100 mT, respectively. It is estimated that the former component is carried by biogenic magnetite, and roughly corresponds to the noninteracting SD component derived from the FORC diagrams, and that the latter component is carried by eolian maghemite, corresponding to the interacting SD component. The χARM/SIRM ratio decreases with increasing concentration of the interacting SD component. This implies that the χARM/SIRM ratio is significantly affected by magnetostatic interactions and that it does not necessarily reflect magnetic grain size. The effect of magnetostatic interactions on natural remanent magnetization acquisition in sediments is not well understood, but if it is similarly sensitive to the SIRM, normalization by ARM in relative paleointensity estimations would overcompensate for the concentration of magnetic grains and cause the significant coherence between the normalized intensity and the normalizer that has been reported in the literature.

Photophysical, photochemical, and electrochemical properties of dendrimers with a dimethoxybenzil core

Three dendrimers consisting of a dimethoxybenzil core and branches that contain two (G0), four (G1), and eight (G2) naphthalene units at the periphery and zero (G0), two (G1), and six (G2) dimethoxybenzene units in the branches have been synthesized and their photophysical, photochemical, and electrochemical properties have been investigated. For comparison purposes, the properties of dimethoxybenzil (MB) and of a dendron containing four naphthalene and three dimethoxybenzene units (D2) have also been studied. The properties of the dendrimers in the ground state (absorption spectra and electrochemical behavior) are those expected for their noninteracting component units. The excited state properties, however, are substantially controlled by electronic interactions between the dimethoxybenzil core and the naphthalene units contained in the branches. In dichloromethane–chloroform 1 : 1 (v/v) solution at 298 K, energy transfer from the lowest excited state (S1) of the naphthalene units to the lower lying S1 excited state of the dimethoxybenzil core takes place with high efficiency. In a rigid matrix at 77 K, selective excitation of the dimethoxybenzil chromophore yields an emission band that exhibits a spectral evolution: in the millisecond time scale it shows a spectral profile very similar to the dimethoxybenzil phosphorescence, whereas in the second time scale it is very similar to the naphthalene-type phosphorescence. Energy transfer from the T1 excited state of the dimethoxybenzil core to the T1 excited state of the naphthalene units takes place at 77 K, but not at 298 K, because the T1 excited state of the dimethoxybenzil core moves to energy lower than that of the naphthalene chromophore. The photochemical results show that the dimethoxybenzil core maintains its intrinsic photoreactivity toward dioxygen, and that on increasing dendrimer generation a photoreaction between core and branches predominates.

Decomposition of ESR Spectra Using MALDI-TOF Mass Spectrometry

ESR (or EPR) spectroscopy on spin-labeled site-directed cysteine mutants is ideally suited for structural studies of membrane proteins due to its high sensitivity and its low demands with respect to sample purity and preparation. Many features can be inferred from the spectral line shape of an ESR spectrum, but the analysis of ESR spectra is complicated when multiple sites with different line shapes are present. Here, we present a method to decompose the spectrum of a doubly labeled peptide that is composed of a singly labeled, noninteracting component and a doubly labeled, dipolar-broadened component using a combination of optical and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The effect on the interspin distance calculation based on the dipolar broadening is quantified and discussed.

Comparison of Electron Paramagnetic Resonance Methods to Determine Distances between Spin Labels on Human Carbonic Anhydrase II

Four doubly spin-labeled variants of human carbonic anhydrase II and corresponding singly labeled variants were prepared by site-directed spin labeling. The distances between the spin labels were obtained from continuous-wave electron paramagnetic resonance spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of line-shape broadening, and computer simulation of line-shape changes. Distances also were determined by four-pulse double electron-electron resonance. For each variant, at least two methods were applicable and reasonable agreement between methods was obtained. Distances ranged from 7 to 24 Å. The doubly spin-labeled samples contained some singly labeled protein due to incomplete labeling. The sensitivity of each of the distance determination methods to the non-interacting component was compared.

Vacuum pyrolysis of commingled plastics containing PVC I. Kinetic study

Thermal decomposition of commingled plastics comprising high and low density polyethylene, polystyrene, polypropylene and poly(vinyl chloride) was investigated under vacuum conditions by dynamic thermogravimetric analysis in the temperature range of 25–600°C. The mixtures were representative of the major polymeric materials found in a municipal plastic waste (MPW) stream. The study focused on the role of each polymer in the stabilization or destabilization of other interacting plastics, as well as the fate of chlorine produced from PVC. First, the decomposition of each single plastic was investigated. Then the binary combination of all above polymers and finally the multicomponent mixture similar to a MPW sample were studied. Two approaches have been applied to study the interaction between components in the commingled plastics. The first approach involved a comparison of the experimental curve of the decomposition of the mixture with a calculated non-interacting component decomposition curve based on the behavior of the individual polymers. The second approach involved a comparison of the kinetic parameters of each plastic in the mixture as determined by two different methods: (1) fitting the single polymer decomposition curve and (2) fitting the peak corresponding to the pyrolysis of one particular polymer on the mixture pyrolysis curve. The results obtained indicate that some interactions occurred during MPW pyrolysis, mainly at high temperatures (>375°C). PS and PVC appear to be the plastics responsible for the interactions through their intermediate pyrolysis products. The chlorine from PVC in the mixture is released almost completely before 375°C, when the conversion of the MPW to pyrolysis products has reached ca. 13%.

微小系の熱力学とその応用

Small system thermodynamics is briefly discussed in relation to statistical mechanics and applied to solutions of noninteracting multi component micelles and vesicles. It is shown that the Gibbs-Duhem equation does not hold for the lipid membranes of vesicles as well as for micelles. Polydispersity of micelles and thermal fluctuations of the extensive thermodynamic functions are discussed, and equations of temperature and pressure dependencies of solubilities of surfactants in water are derived.

Subunit interaction of rabbit muscle phosphofructokinase: effects of purification procedures

Structural, physical, and kinetic properties of rabbit muscle phosphofructokinase (PFK) purified by three different procedures were monitored in order to determine the effect of various purification procedures on the dynamics of subunit interaction. PFK was purified by three commonly used procedures: (1) differential heat precipitation [Kemp, R. G. (1972) Methods Enzymol. 42, 71-77], (2) differential heat and alcohol precipitation [Ling, R. H., Marcus, F., & Lardy, H. A. (1965) J. Biol. Chem. 240, 1893-1899], and (3) differential salt fractionation [Hesterberg, L. K., & Lee, J. C. (1980) Biochemistry 19, 2030-2039]. The physical, kinetic, and structural properties of these three preparations show that these proteins are not identical. Sedimentation velocity studies show that PFK purified by method 3 self-associates rapidly and that the system is thermodynamically homogeneous. The presence of an inactive or noninteracting component is not observed within an 8-h time limit. In contrast, PFK purified by method 1 or 2 is heterogeneous. In these preparations, a slowly sedimenting, noninteracting, inactive form of PFK is present. The remaining active protein is not stable but continuously converts to an inactive form. Active PFK can be fractionated from this inactive form by sedimentation. This active fraction behaves as a thermodynamically homogeneous system, and the subunits undergo rapid association-dissociation in a manner similar to PFK purified by method 3. Kinetic studies on these three preparations show that the inclusion of a heat and/or alcohol step in the purification procedure yields an enzyme that is less stable, has a lower specific activity, requires DTT for full activation, and is more susceptible to inhibition by ATP.(ABSTRACT TRUNCATED AT 250 WORDS)

Locally rotationally symmetric cosmological model containing a nonrotationally symmetric electromagnetic field

The Einstein-Maxwell equations are integrated for a locally rotationally symmetric, Bianchi type-V spacetime containing a source-free, null, electromagnetic field. Solutions are also given for an added, noninteracting component with equation of state $P=\ensuremath{\rho}$. A striking feature of the models is that the rotational symmetry of the spatially homogeneous geometry is not shared by the electromagnetic field. Field components orthogonal to the symmetry axis define preferred directions, breaking rotational symmetry. The effects of matter and the electromagnetic field on the singularity structure are also examined. It is found that although the ratio of electromagnetic energy density to mass energy density approaches zero as the singularity is approached, the electromagnetic field influences the nature of the singularity.

INDO-UHF-CI Calculations of the Electronic Structure of Formaldehyde–Hydrogen Systems

Abstract The electronic structures were calculated for the ground and several excited states of systems composed of a formaldehyde molecule and a hydrogen atom at various relative positions by means of an INDO-UHF-CI method, in order to elucidate the hydrogen-abstracting process of excited carbonyl compounds. The results were presented and discussed by means of the adiabatic potential energy curves, by means of configuration analysis using the various states of the non-interacting component species as reference, and by means of electron-density maps. The results showed in a concrete way that the process may proceed through an intermediate charge-transfer state, and the electron-density maps had features suggesting an attractive force acting on the positively charged hydrogen atom.