Constrained supersymmetric flipped SU(5) GUT phenomenology

We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, M _in , above the GUT scale, M _GUT. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino χ and the lighter stau [(t)\tilde]₁{\tilde{\tau}_{1}} is sensitive to M _in , as is the relationship between m _χ and the masses of the heavier Higgs bosons A,H. For these reasons, prominent features in generic (m _1/2,m ₀) planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to M _in , as we illustrate for several cases with tan β=10 and 55. However, these features do not necessarily disappear at large M _in , unlike the case in the minimal conventional SU(5) GUT. Our results are relatively insensitive to neutrino masses.     

Crystal structure of stereocomplex of poly(L-lactide) and poly(D-lactide)

An equimolar mixture of poly(L-lactide) and poly(D-lactide) was crystallized into a stereocomplex whose crystal system is triclinic (P1) with cell dimensions: a = 0.916 nm, b = 0.916 nra, c (chain axis) = 0.870 nm, α = 109.2°, β - 109.2°, and γ = 109.8°. In the unit cell, a poly(L-lactide) segment and a poly (D-lactide) segment are contained as a pair and packed laterally in parallel fashion. The L- and D-poly(lactides) in the complex take a 3₁ helical conformation, which is a little extended from a 10₃ helix in the homopolymer crystal with the α-form. Homopolymers are also able to take the 3₁ helical conformation and form the β-form crystal. The 3₁ helix in the homopolymer crystal is less stable than the 10₃ one, and hence the β-form is easily transformed to the α-form by annealing.     

SU(2)L×SU(2)R×U(1) gauge model

We determine here the most general electroweak interaction based on the groupSU(2)_L×SU(2)_R×U(1). When we rotate theZ ₁,Z ₂ basis to theZ,D basis such that the total interaction ofZ with the right-handed current is zero, we obtain an interaction that is free of triangle anomalies. This condition enables us to know the angle through whichZ ₁,Z ₂ basis is to be rotated. We show that the triangle anomaly free interaction obtained by others is contained here as a special case. We also determine the triangle anomaly free weak interaction whenever the neutral (Z,D) bosons are mass eigenstates and show that it reduces to the neutral sector of the standard model whenever g _R ² goes to infinity. The charged sector is also developed here. The most general elements of the masssquared matrix of theZ,D bosons are evaluated. The masses of the left- and right-handed charged bosons are also determined.     

Huygens' Principle,Dirac Operators,and Rational Solutions of the AKNS Hierarchy

We prove that rational solutions of the AKNS hierarchy of the form q=σ/τ and r=ρ/τ, where (σ,τ,ρ) are certain Schur functions, naturally yield Dirac operators of strict Huygens' type, i.e., the support of their fundamental solutions is the surface of the light-cone. This strengthens the connection between the theory of completely integrable systems and Huygens' principle by extending to the Dirac operators and the rational solutions of the AKNS hierarchy a classical result of Lagnese and Stellmacher concerning perturbations of wave operators. Mathematics Subject Classifications (2000) 37K10, 35Qxx, 35B40.     

Comparative study of theSp (2,R) and theSp(6,R) models and an application to theBa chain of isotopes

We investigate the Sp(2, R) model for light and heavy nuclei and compare it to recent applications of the Sp(6, R) model. The same Hamiltonian is used and the basis states will have good angular momentum. We not only confirm that the restricted space of the Sp(6, R) model gives the dominant contribution but also that there is no practical difference from the Sp(6, R) model calculations. The Sp(2, R) model is then applied to the chain of Ba-isotopes which show, according to a recent application of the geometrical model, a dominant prolate behavior with an important γ-unstable component. They represent limiting cases where the Sp(2, R) model can be put to an extreme test. Work supported by CONACyt (No. E120-550/95).     

Infrared quantum cutting conversion luminescence of Tb(0.7)Yb(3):FOV

The infrared quantum cutting of oxyfluoride nanophase vitroceramics Tb(0.7)Yb(3):FOV has been studied in the present paper. The actual quantum cutting efficiency formula calculated from integral fluorescence intensity is extended to the case of Tb(0.7)Yb(3):FOV. The visible and the infrared fluorescence spectra and their integral fluorescence intensities are measured from static fluorescence experiment. Lifetime curve is measured from dynamic fluorescence experiment. It is found that the total actual quantum cutting efficiency η of the excited ⁵D₄ level is about 93.7%, and that of excited (⁵D₃, ⁵G₆) levels is 93.5%. It is also found that the total theoretical quantum cutting efficiency upper limit η_x%Yb of the 485.5 nm excited <⁵D₄ level is about 121.7%, and that of 378.5 nm excited (⁵D₃, ⁵G₆) levels is 137.2%.     

Microorganisms baroinactivation of germinated mung bean (green gram) seeds

It is possible to describe the pressure degradation of microorganisms as being analogous to thermal inactivation. Equation for baroinactivation is derived from thermal death time (TDT) model D _p = D _pref 10^{(pref-p)/z _p} , where D _pref is decimal reduction time at the reference pressure (min), p _ref is the reference pressure (MPa), z _p is the pressure increase (MPa) required to reduce the D _p value by a factor of 10. This method was used for the calculation of baroinactivation model parameters of the total number of microorganisms of pressurized germinated mung bean (green gram) seeds (Vigna radiata (L.) Wilczek). Microbial contamination of germinated mung bean (green gram) seeds can be effectively decreased by treatment at a high pressure of 400 MPa, time of pressurization 5 min.     

Luminescence quenching of [Ru(bpy)3] by ruthenium(II) tetraphosphite complexes with different phosphite ligands

The luminescence quenching of excited Tris(2,2-bipyridine)ruthenium(II) ions by trans-[RuCl₂{P(OR)₃}₄] complexes with different alkyl chain ligands (R=C₂H₅, C₂H₅Cl, ⁿC₄H₉, ⁱC₃H₇ o-tolyl and ^tC₄H₉) was investigated. None of the acceptor Ru(II) phosphite complexes were luminescent, and the rate constants of the bimolecular system were determined within the range of 1.15 and 0.28×10⁸ M⁻¹ s⁻¹ for R=C₂H₅ and ^tC₄H₉, respectively. The results indicate a direct effect of the alkyl chains in the rate constants, showing a decrease of k_q as a function of increased of the alkyl chains (R) in the ruthenium(II) tetraphosphite complexes. The greater the R group content in the phosphite ligand, the more difficult the electron transfer is.     

Computation and analysis of the dynamic structure factor S(k, ω) for small wave vectors

Molecular dynamics (MD) calculations have been performed for the Lennard-Jones (12-6) potential function using 2048 particles. Using conventional parameters the results may be compared with those for liquid argon.

The dynamic structure factor S(k, ω) has been determined both by Fourier inversion of the intermediate scattering function F(k, t) and from the longitudinal current-current correlation function C _∥(k, t). Particular attention was paid to the recurrence time of the system. The results for S(k, ω) by the two methods agree within 5 per cent for the whole region of small k-vectors considered. Double Fourier inversion of the van Hove function G(r, t) led to insufficiently accurate results for these small k-values. In view of the present data, the MD-results of Levesque et al. [1] for S(k, ω) have only a qualitative character. These latter data appear to contain truncation errors due to incomplete Fourier transformations.

Using a hydrodynamic assumption for F(k, t) we were able to extract the transport coefficients, the velocity of sound and the ratio of the specific heats in the limit of large wave lengths or small k. The velocity of sound was obtained by exploiting the MD generated anomalous dispersion curve of sound waves. Anomalous dispersion was found to set in for kσ ～ 0·25. A sound speed of 880 ms^-1 has been determined which is in excellent agreement with experimental values for liquid argon. The total error for the MD value amounts to about 5 per cent. In contrast, the ratio of the specific heats γ and the transport coefficients D _T and Γ (thermal diffusivity and sound attenuation) were determinable only with an accuracy of 15 per cent due to the need for larger extrapolations. Nevertheless, we found D _T, Γ and γ in agreement with experimental values within 5-10 per cent.     

Selective photoconductivity induced in PbTe(Ga) by a local phonon mode

Selective photoconductivity at frequency ω=155 cm⁻ was discovered in PbTe(Ga) narrow-gap semiconductors at liquid-nitrogen temperatures. The corresponding energy is much lower than all characteristic energies of the electronic spectrum of the semiconductor. The effect is attributed to optical excitation of a local vibrational mode of an impurity center leading to delocalization of the electrons. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 5, 342–346 (10 March 1996)     

Theory of gyro devices with thin electron beams (large-orbit gyrotrons)

It is shown for a precisely aligned electron beam of small thickness in a large-orbit gyrotron that high cyclotron harmonics (up to s⩽5) can be selectively excited with an electronic efficiency that is acceptable for some applications (1–10%). When the quality of the electron beam is high, the selective properties are maintained even for modes with high radial indices, raising hopes that this method can be used to obtain coherent radiation not only in the millimeter but also in the entire submillimeter wavelength range. A method for taking into account the space-charge effects is developed, and it is shown that the corresponding effects can be important at relatively small values of the electron pitch factor. The results of the analysis and preliminary experiments reveal the possibility of creating high-power compact sources of submillimeter radiation for the spectroscopy of various media, the diagnostics of dense plasmas, and some other applications. Fiz. Tekh. Poluprovodn. 68, 91–98 (October 1998)     

Radiation chemistry of tris(acetylacetonato) cobalt(iii) in aqueous solutions

Abstract

On radiolysis tris(acetylacetonato) cobalt(III) in aqueous solutions is found to get reduced by reaction with (1) hydrated electrons, (2) H atoms, (3) OH radicals and (4) C₂H₂OH radicals. The bimolecular rate constants for the first three reactions, determined by competition kinetics are: 4 × 10¹⁰, 2.3 × 10⁹ and 4.7 × 10⁹ M^?1sec^?1 respectively. Absorption spectra of the irradiated solutions indicate the formation of bis(acetylacetonato) cobalt(II) from reaction (1), but not from (3). The total cobaltous yield in air-free solutions is given byG(Co⁺⁺) = 5.6 and 6.5 at pH 6.5 and 1 respectively. It appears that G_eaq- ∽ _H ⁺ G_oH ∽ 2.8 in neutral solutions. Considerations of material balance for the primary yields of radiolysis of water suggest the possibility that the so-called independent H-atoms in neutral solutions are probably excited water molecules or ion-pairs.     

Internal friction in directed-crystallization (Cu-Sn)-Nb alloys

The distinctive features of the low-frequency internal friction Q ⁻¹(T) of (Cu-Sn)-Nb composites at high temperatures (up to 400°C) are investigated for strains in the range 10⁻⁵–10⁻⁴. Considerable hysteresis of Q ⁻¹(T) in the heating-cooling cycle is recorded, including the presence of a minimum at ∼175°C when the sample is heated to 400°C and two peaks P ₂ (at 280°C) and P ₁ (at ∼100°C) when the sample is cooled from 400°C. The activation energy of the anomalous internal friction background (up to 175°C), the oxygen diffusion parameters, and the oxygen concentration in the niobium fibers (all of which govern the peak P ₂) are calculated, and the value and temperature dependence of the yield point of the bronze matrix (which govern the peak P ₁) are estimated. Zh. Tekh. Fiz. 68, 114–117 (November 1998)     

The Asymptotic Limits of Zero Modes of Massless Dirac Operators

Asymptotic behaviors of zero modes of the massless Dirac operator H = α · D + Q(x) are discussed, where α = (α₁, α₂, α₃) is the triple of 4 × 4 Dirac matrices, , and Q(x) = (q _jk (x)) is a 4 × 4 Hermitian matrix-valued function with | q _jk (x) | ≤ C 〈x〉^−ρ, ρ > 1. We shall show that for every zero mode f, the asymptotic limit of |x|² f (x) as |x| → + ∞ exists. The limit is expressed in terms of the Dirac matrices and an integral of Q(x) f (x).      

Quantum chemical studies on (ZnO)n/(NiO)n heterostructured nanoclusters

The structural stability and electronic properties of (ZnO)_n, (NiO)_n, (ZnO)_n/(NiO)_n for n = (1 to 4) and 3D structures were studied using density functional theory. The geometrical optimisation of clusters implies that when the atoms in the cluster increase it leads to an increase in its stability. The stability drastically increases for the heterostructure of (ZnO)_n/(NiO)_n. The dipole moment of the clusters depends on the geometry of the cluster and it is found to be minimum for heterostructures representing more neutralised clusters. HOMO-LUMO energies, ionisation potential, electron affinity, chemical hardness, binding energies and vibrational analysis of different clusters are calculated and reported. The adsorption of CO on the different sites of nanoclusters are studied and discussed.     

Magnetic quantum oscillations in the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br

The interlayer magnetoresistance of the organic superconductor κ-(BEDT-TTF)₂Cu[N(CN)₂)Br is measured at ambient pressure and under pressures of up to 12.5 kbar. In addition to the slow Shubnikov-de Haas oscillations with a frequency of ≃150 T observed at P⩾5 kbar, rapid oscillations attributed to the magnetic breakdown orbit enveloping an area equal to 100% of the area of the Brillouin zone are found to emerge above B=20 T. The latter oscillations are observed at ambient pressure as well as under pressures of up to 9 kbar. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 3, 190–194 (10 August 1997) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Molecular Packing in Crystalline Domains of Unsymmetrical Poly(benzoxazole-imide): Investigation using Modeling of a Model Compound

To probe the molecular packing in crystalline domains of an unsymmetrical poly(benzoxazole-imide) (BPDA-BOA) introduced alternating phenylbenzoxazole and bisphthalimide units via the two-step polymerization of 5-amino-2-(4- aminophenyl)benzoxazole (BOA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), the crystal structure of its model compound, 5-phthalimido-2-(4-phthalimidophenyl)benzoxazole (PA-BOA), was investigated using powder wide-angle X-ray diffraction (WAXD) combined with molecular modeling using a Materials Studio program. Powder WAXD pattern of the model compound can be well indexed in terms of amonoclinic unit cell with parameters of a = 12.005 Å, b = 3.837 Å, c = 23.562 Å, β = 96.711°. There are two molecules in the unit cell with the space group of P2 (3). Based on the crystal structure of the model compound powders and the WAXD analysis of poly(benzoxazole-imide) film, it can be concluded that the projection of the monomer repeat length of the poly(benzoxazole-imide) chains in the chain directionis around 19.0 Å, and the interchain side-by-side distance and face-to-face distance between the centroids of two neighboring BPDA-BOA chains are around 6.10 and 4.01 Å, respectively. The difference of molecular packing between the poly(benzoxazole-imide) chains in their crystalline domains and the model compounds in their crystals are also presented. Both the side-by-side and face-to-face π-π stacking distances between two neighboring polymer chains in the poly(benzoxazole-imide) crystalline domains are significantly larger than the corresponding values between two neighboring molecules in the model compound crystals due to a more kinked and twisted conformation.     

Atomic and electronic structures of GaAs (001) surface

The atomic and electronic structures of α, β, β₂, and ζ reconstructions for the Ga-terminated GaAs (001)-(4×2) surface are investigated in the framework of the pseudopotential approach. Total, surface, and local densities of electron states, electron-energy spectra, and relative surface energies of the structures under consideration are calculated. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 44–52, October, 2006.     

Noncommutative Dynamics of Random Operators

We continue our program of unifying general relativity and quantum mechanics in terms of a noncommutative algebra А on a transformation groupoid Γ = E × G where E is the total space of a principal fibre bundle over spacetime, and G a suitable group acting on Γ . We show that every a ∊ А defines a random operator, and we study the dynamics of such operators. In the noncommutative regime, there is no usual time but, on the strength of the Tomita–Takesaki theorem, there exists a one-parameter group of automorphisms of the algebra А which can be used to define a state dependent dynamics; i.e., the pair (А, ϕ), where ϕ is a state on А, is a “dynamic object.” Only if certain additional conditions are satisfied, the Connes–Nikodym–Radon theorem can be applied and the dependence on ϕ disappears. In these cases, the usual unitary quantum mechanical evolution is recovered. We also notice that the same pair (А, ϕ) defines the so-called free probability calculus, as developed by Voiculescu and others, with the state ϕ playing the role of the noncommutative probability measure. This shows that in the noncommutative regime dynamics and probability are unified. This also explains probabilistic properties of the usual quantum mechanics.