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Full-Text Articles in Physical Sciences and Mathematics
Photoluminescence Of 1-D Copper(I) Cyanide Chains: A Theoretical Description, Craig A. Bayse, Timothy P. Brewster, Robert D. Pike
Photoluminescence Of 1-D Copper(I) Cyanide Chains: A Theoretical Description, Craig A. Bayse, Timothy P. Brewster, Robert D. Pike
Arts & Sciences Articles
Solid copper(I) cyanide occurs as extended one-dimensional chains with interesting photophysical properties. To explain the observed luminescence spectroscopy of CuCN, we report a series of computational studies using short bare and potassium-capped [Cun(CN)n+1] − (n = 1, 2, 3, 4, 5, and 7) chains as CuCN models. On the basis of TD-DFT calculations of these model chains, the excitation transitions in the UV spectrum are assigned as Laporte-allowed π−π transitions from MOs with Cu 3dπ and CN π character to empty MOs with Cu 4p and CN π* character. Transitions between the HOMO (3dz …
Oscillation Regularity In Noise-Driven Excitable Systems With Multi-Time-Scale Adaptation, William H. Nesse, Christopher A. Del Negro, Paul C. Bressloff
Oscillation Regularity In Noise-Driven Excitable Systems With Multi-Time-Scale Adaptation, William H. Nesse, Christopher A. Del Negro, Paul C. Bressloff
Arts & Sciences Articles
We investigate oscillation regularity of a noise-driven system modeled with a slow after-hyperpolarizing adaptation current (AHP) composed of multiple-exponential relaxation time scales. Sufficiently separated slow and fast AHP time scales (biphasic decay) cause a peak in oscillation irregularity for intermediate input currents I, with relatively regular oscillations for small and large currents. An analytic formulation of the system as a stochastic escape problem establishes that the phenomena is distinct from standard forms of coherence resonance. Our results explain data on the oscillation regularity of the pre-Bötzinger complex, a neural oscillator responsible for inspiratory breathing rhythm generation in mammals.
Parametric Model Discrimination For Heavily Censored Survival Data, Lawrence Leemis, A. D. Block
Parametric Model Discrimination For Heavily Censored Survival Data, Lawrence Leemis, A. D. Block
Arts & Sciences Articles
Simultaneous discrimination among various parametric lifetime models is an important step in the parametric analysis of survival data. We consider a plot of the skewness versus the coefficient of variation for the purpose of discriminating among parametric survival models. We extend the method of Cox & Oakes from complete to censored data by developing an algorithm based on a competing risks model and kernel function estimation. A by-product of this algorithm is a nonparametric survival function estimate.
Semiclassical Theory Of The Structure Of The Hydrogen Spectrum In Near-Perpendicular Electric And Magnetic Fields: Derivations And Formulas For Einstein-Brillouin-Keller-Maslov Quantization And Description Of Monodromy, Christopher Robert Schleif, John B. Delos
Semiclassical Theory Of The Structure Of The Hydrogen Spectrum In Near-Perpendicular Electric And Magnetic Fields: Derivations And Formulas For Einstein-Brillouin-Keller-Maslov Quantization And Description Of Monodromy, Christopher Robert Schleif, John B. Delos
Arts & Sciences Articles
In a previous paper [Schleif and Delos, Phys. Rev. A 76, 013404 (2007)] we described the spectrum of hydrogen atoms in near-perpendicular electric and magnetic fields. We displayed a number of previously unrecognized structures in the spectrum, most of which are connected with a classical phenomenon called “nontrivial monodromy of action and angle variables in a Hamiltonian system,” or simply “monodromy.” In that paper, we presented only the results, giving predictions of what to look for in various ranges of electric and magnetic fields. Here we present the underlying theory. Starting from Kepler action and angle variables, we give a …
Bis{L-2,20-[1,10-(Ethane-1,2-Diyldinitrilo)- Diethylidyne]Diphenolato}Bis[(Benzoatojo)Manganese(Iii)] Dihydrate, V. S. Thampidas, T. Radhakrishnan, Robert D. Pike
Bis{L-2,20-[1,10-(Ethane-1,2-Diyldinitrilo)- Diethylidyne]Diphenolato}Bis[(Benzoatojo)Manganese(Iii)] Dihydrate, V. S. Thampidas, T. Radhakrishnan, Robert D. Pike
Arts & Sciences Articles
The title compound, [Mn2(C18H18N2O2)2Cl2], was synthesized by the reaction between manganese(II) o-chlorobenzoate and the Schiff base generated in situ by the condensation of ethane-1,2-diamine and o-hydroxyacetophenone. The centrosymmetric dimer contains two Jahn-Teller-distorted manganese(III) ions, each in an octahedral geometry, connected through two phenoxy bridges from two ligands.
Static And Dynamical Manifestations Of Hamiltonian Monodromy, John B. Delos, Christopher Robert Schleif, G. Dhont
Static And Dynamical Manifestations Of Hamiltonian Monodromy, John B. Delos, Christopher Robert Schleif, G. Dhont
Arts & Sciences Articles
The word 'monodromy' means 'once around a course', and it refers to changes that might occur when a system goes around some closed loop [1]. We discuss here a phenomenon whose proper name is 'nontrivial monodromy of action and angle variables in a Hamiltonian system'; for the obvious reason, we just call it 'Hamiltonian monodromy'. In this paper we describe two manifestations of Hamiltonian monodromy: a manifestation in a time-dependent classical system, and a manifestation in a stationary quantum system. Then we give a brief description of the mathematical theory, and finally close with a short survey of previous work …
Crystal Structure Of Di-Iso-Butylammonium Thiolactatotriphenylstannate, Olaniran Atchade, Xueqing Song, Robert Pike, George Eng
Crystal Structure Of Di-Iso-Butylammonium Thiolactatotriphenylstannate, Olaniran Atchade, Xueqing Song, Robert Pike, George Eng
Arts & Sciences Articles
The title compounds, [(iso-C4H9)2NH2][SnPh3(O2CCH(CH3)S)], crystallized in a monoclinic space group P21/n with the following cell parameters: a = 9.8537(2)Å, b = 16.7775(3)Å, c = 17.5845(3)Å, β = 103.7740(10)°, V = 2823.48(9)Å3, Z = 4 and Dx = 1.375 Mg m-3. The structure was refined to a final R value of 0.0222 for 5042 reflections [I > 2σ(I)]. The structure of the complex is ionic consisting of an anionic triphenyltin moiety and a cationic di-iso-butylammonium portion. In addition, a hydrogen bonding network between the cations and anions was observed.
Aqua {2,2-[Ethane-1,2-Diylbis(Nitrilomethylidyne)]Diphenolato}(3-Nitrobenzoato)Manganese(Iii), V. S. Thampidas, T. Radhakrishnan, Robert D. Pike
Aqua {2,2-[Ethane-1,2-Diylbis(Nitrilomethylidyne)]Diphenolato}(3-Nitrobenzoato)Manganese(Iii), V. S. Thampidas, T. Radhakrishnan, Robert D. Pike
Arts & Sciences Articles
The title compound, [Mn(C16H14N2O2)(C7H4NO4)(H2O)], is a Jahn-Teller-distorted manganese(III) monomer with an octahedral geometry. The tetradentate Schiff base accommodates the MnIII ion at the centre of a nearly planar square. The axial positions are occupied by a monodentate carboxylate group and a water molecule. Adjacent monomers interact through hydrogen bonding between the noncoordinated C=O group of the carboxylate and the coordinated water molecule to produce chains extending parallel to the b axis.
2,2,3,30-Tetraphenyl-7,70-Biquinoxaline, Eric E. Dueno, Ricky J. Paul, Ralph N. Salvatore, Robert D. Pike
2,2,3,30-Tetraphenyl-7,70-Biquinoxaline, Eric E. Dueno, Ricky J. Paul, Ralph N. Salvatore, Robert D. Pike
Arts & Sciences Articles
In the crystal structure of the title compound, C40H26N4, molecules reside on crystallographic centers of inversion and are linked via C-HN interactions about inversion centers into one-dimensional chains: longer C-H(arene) interactions complete the intermolecular interactions.
Poly[L-2-Aminopyrazine-J2 N1 :N4 - L-Cyanido-Copper(I)]: A Three-Dimensional Network From Laboratory Powder Diffraction Data, Silvina Pagola, Robert D. Pike, Kathryn Dekrafft, Tristan A. Tronic
Poly[L-2-Aminopyrazine-J2 N1 :N4 - L-Cyanido-Copper(I)]: A Three-Dimensional Network From Laboratory Powder Diffraction Data, Silvina Pagola, Robert D. Pike, Kathryn Dekrafft, Tristan A. Tronic
Arts & Sciences Articles
In the title compound, [Cu(CN)(C4H5N3)]n or [Cu(-CN)(-PyzNH2)]n (PyzNH2 is 2-aminopyrazine), the CuI center is tetrahedrally coordinated by two cyanide and two PyzNH2 ligands. The CuI-cyano links give rise to [Cu-CN] chains running along the c axis, which are bridged by bidentate PyzNH2 ligands. The three-dimensional framework can be described as being formed by two interpenetrated three-dimensional honeycomb-like networks, both made of 26-membered rings of composition [Cu6(-CN)2(-PyzNH2)4].