Remarks on a recent article of Ch. Obcemea and E. Brändas on the theory of subdynamics

In a recent paper on the theory of subdynamics, Ch. Obcemea and E. Brändas (Ann. Phys (N.Y.)151 (1983), 383–430) claimed to correct a recently published result (M. Courbage, J. Math. Phys.23 (1982), 646, 652). It is shown that this criticism is unfounded. Some additional remarks are made.     

Reply to “on one of the ways of application of the lattice-gas model to describe the kinetics of desorption” by V.P. Zhdanov

Zhdanov's criticism on the applicability of our desorption rate which is proportional to the factor θ/(1−θ), where θ is the surface coverage, is shown to be irrelevant. To be precise, the difference between our and former conventional transition state theory is clarified. Also, the differences between our model and the precursor model are stressed, although these two models result in a similar desorption rate.     

Corresponding member of the Russian Academy of Sciences M.G. Meshcheryakov (1910–1994) on the centennial of his birth

Chronicles

Corresponding member of the Russian Academy of Sciences M.G. Meshcheryakov (1910–1994) on the centennial of his birth     

A remark on the axisymmetric Chen et al. solution of the Poincaré gauge theory

Recently the search for exact solutions of the Poincaré gauge theory of gravity was highlighted by the independent discovery of two Kerr-type solutions with dynamic torsion. Some properties of these axisymmetric solutions, found by Chen et al. and by McCrea et al., are compared and put into proper perspective. In particular we show that the Chen et al., solution, in marked contrast to the more general McCrea et al. solution, belongs to a class of quadratic Poincaé gauge lagrangians of a highly degenerate nature, which admits non-unique solutions already in the limit of spherical symmetry.     

Influence of final-state interaction on incoherent pion photoproduction on the deuteron in the region of the Δ-resonance

The influence of final-state NN and πN rescattering in incoherent pion photoproduction on the deuteron has been investigated. For the elementary photoproduction operator an effective Lagrangian model is used which describes well the elementary reaction. The interactions in the final two-body subsystems are taken in separable form. While NN rescattering shows quite a significant effect, particularly strong for neutral pion production, πN rescattering is almost negligible. Inclusion of such effects leads to an improved and quite satisfactory agreement with experiment. Received: 12 August 2002 / Accepted: 11 September 2002 / Published online: 17 January 2003 RID="a" ID="a"Present address: Physics Department, Faculty of Science, South Valley University, Sohag, Egypt. RID="b" ID="b"e-mail: arenhoev@kph.uni-mainz.de Communicated by V. Vento     

A theoretical spectroscopic study of single ammonia molecules adsorbed on the surface of fcc-type argon clusters. Surface effects on the ν 2 vibration-inversion mode

Ammonia monomers have been adsorbed on argon clusters at low temperature K by Rohmund and Huisken [#!frfh97!#] using the pick-up technique. They measured the spectrum of the NH₃ molecules in the region of the umbrella mode. Two broad bands centered around 970 and 1000 cm^-1 with finer details were observed. The authors attempted to interpret the obtained spectrum on the basis of the free rotation motions of the molecules. In this paper semi-empirical atom-atom potential energy calculations are performed for the ammonia monomer adsorbed on a rigid face-centered-cubic (fcc)-type surface of the argon cluster. In the equilibrium position of the rigid molecule on the cluster surface the orientational potential energy surface exhibits two quasi-equivalent minima separated by a potential barrier of about 100 cm^-1. The symmetry of the molecular vibration-inversion double-well potential is destroyed; the inversion motion is then forbidden in the ground state. On the basis of the two adsorption orientations, the vibrational frequency shifts are calculated and the obtained infrared bar-spectrum agrees with the experimental one. Received 6 April 1999 and Received in final form 19 July 1999     

Reply to the Comment by A.W. Thomas et al. on “The role of the orbital angular momentum in the proton spin”

The orbital angular momenta L^u and L^d of up- and down-quarks in the proton are estimated as functions of the energy scale as model independently as possible on the basis of Ji's angular-momentum sum rule. This analysis indicates that L ^u - L ^d is large and negative even at the low energy scale of nonperturbative QCD, in contrast to Thomas' similar analysis based on the refined cloudy bag model. We pursuit the origin of this apparent discrepancy and suggest that it may have a connection with the fundamental question of how to define quark orbital angular momenta in QCD.     

Empirical Study on the Volatility of the Hang-Seng Index

We study the statistical properties of volatility of price fluctuation for the Hang-Seng index in the Hong Kong stock market, they are measured by locally averaging over a time window T, the absolute value of price change over a short time interval Δt. The data include minute-by-minute records of the Hang-Seng index from 3 January 1994 to 28 May 1997. We find that the cumulative distribution of the volatility is consistent with the asymptotic power-law behaviour, characterized by the power exponent μ= 2.12 ± 0.04, different from that found in the previous studies as μ≈3. The volatility distribution remains the same asymptotic power-law behaviour for the time scales from T = 10 rain to T - 80 rain. Furthermore, we investigate the volatility correlations by using the power spectrum analysis and detrended fluctuation analysis. Both the methods show a long-range power-law decay with the exponent α=0.636±0.002.     

Effects of the spin–orbit coupling on the vacancy-induced magnetism on the honeycomb lattice

The local magnetism induced by vacancies in the presence of the spin–orbit interaction is investigated based on the half-filled Kane–Mele–Hubbard model on the honeycomb lattice. Using a self-consistent mean-field theory, we find that the spin–orbit coupling will enhance the localization of the spin moments near a single vacancy. We further study the magnetic structures along the zigzag edges formed by a chain of vacancies. We find that the spin–orbit coupling tends to suppress the counter-polarized ferrimagnetic order on the upper and lower edges, because of the open of the spin–orbit gap. As a result, in the case of the balance number of sublattices, it will suppress completely this kind of ferrimagnetic order. But, for the imbalance case, a ferrimagnetic order along both edges exists because additional zero modes will not be affected by the spin–orbit coupling.     

Kinetic mechanisms of the uptake of atmospheric gases on the surface of sea salts. ClNO3 uptake on MgCl2 · 6H2O/NaCl

The uptake coefficients γ of chlorine nitrate on MgCl₂ · 6H₂O crystallites and a MgCl₂ · 6H₂O-NaCl mixture deposited from an aqueous solution are measured using a flow reactor with a movable salt-substrate-coated insert equipped in combination with a mass spectrometer at 295–428 K, [ClNO₃] = (0.2?12) × 10¹² cm^?3, and [H₂O] = 1.0 × 10¹² ? 4.3 × 10¹⁵ cm^?3. Immediately after the exposure of the salt substrate to a ClNO₃ flow, γ(t) decreases exponentially with time, γ(t) = γ₀ × exp(?t/τ) + γ _s , to a steady-state level, γ _s , which depends on the temperature and the ClNO₃ and H₂O concentrations. The main gas-phase product is Cl₂, HOCl appears only when water vapor is admitted into the reactor. The coefficient of steady-state uptake on wetted MgCl₂ · 6H₂O at 295 K can be described by the approximation γ = a + b [H₂O] with a = 3.5 × 10^?3 cm³ and b = 3.2 × 10^?18 cm³. The mechanism of the uptake of ClNO₃ on MgCl₂ · 6H₂O is discussed. The experimental data are treated within the framework of a steady-state uptake model to estimate the heat of adsorption of ClNO₃ on MgCl₂ · 6H₂O (Q _ad = 62 kJ/mol) and the activation energy of the bimolecular heterogeneous reaction ClNO₃ + Z _s = 2Cl₂ + Mg(NO₃)₂ · 6H₂O (E _a = 21.8 kJ/mol; Z _s denotes a ClNO₃-MgCl₂ · 6H₂O surface complex). When the MgCl₂ · 6H₂O: NaCl is varied from 0 to ～3 wt %, the steady-state uptake coefficient changes from the value corresponding to uptake on pure NaCl to that characteristic of uptake on pure MgCl₂ · 6H₂O.     

Influence of annealing on the structure of nanoporous oxide films on the surface of titanium‒aluminum powder alloy

Oxide films obtained during anodization of Ti?40% Al sintered powder samples in fluorine-containing electrolytes are investigated. With scanning electron microscopy and X-ray phase analysis, it is demonstrated that an X-ray amorphous nanoporous anodic oxide film is formed on the surface of the powder microparticles under optimal anodization conditions. After annealing at T = 1093 K in air and vacuum (10^?2 Pa), the oxide films are revealed to crystallize with its regular porous structure retained. The composition of the polycrystalline anodic-oxide films annealed in air is a mixture involving TiO₂ (anatase and rutile) and α- and γ-Al₂O₃ phases and Ti₂O₃ and Al₂TiO₅ traces. The vacuum annealing process makes it possible to identify TiO₂, in which anatase is the main phase, α- and γ-Al₂O₃, and Ti₂O₃ and TiO traces. However, rutile is not revealed. The presented results indicate that the application of the anodic nanostructuring of Ti?40% Al powders is promising for the obtainment of new photocatalytic active nanomaterials.     

Comment on “On the Barut-Vigier model of the hydrogen atom” by Samsonenko et al.

Contrary to the claim of Samsonenko, Tahti and Ndahayo [Phys. Lett. A 220 (1996) 297], it is found that the ground state energy for a hydrogen atom in the Barut-Vigier potential is E = 13.6 eV.     

The effect of γ radiation on the determination of the antineutrino angular distribution from experiments on the β decay of polarized neutrons

In experiments on the β decay of polarized neutrons where only the electron and proton momentum distributions are observed and the γ radiation is not registered, the asymmetry factor B of the antineutrino angular distribution cannot be obtained rigorously — the value of B is only estimated on the average by taking into consideration the expectation (mean) value 〈B〉 and the rms deviation ΔB. The resulting unavoidable ambiguities in the determination of B amount to several percent, which is significant for the present-day experimental attempts to obtain B to very high precision ∼(0.1–1)%. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 10, 681–685 (25 May 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Influence of the Investor’s Behavior on the Complexity of the Stock Market

One of the pillars of the finance theory is the efficient-market hypothesis, which is used to analyze the stock market. However, in recent years, this hypothesis has been questioned by a number of studies showing evidence of unusual behaviors in the returns of financial assets (“anomalies”) caused by behavioral aspects of the economic agents. Therefore, it is time to initiate a debate about the efficient-market hypothesis and the “behavioral finances.” We here introduce a cellular automaton model to study the stock market complexity, considering different behaviors of the economical agents. From the analysis of the stationary standard of investment observed in the simulations and the Hurst exponents obtained for the term series of stock index, we draw conclusions concerning the complexity of the model compared to real markets. We also investigate which conditions of the investors are able to influence the efficient market hypothesis statements.     

Origin of the E.S.R. hyperfine anisotropy and the cos2 θ rule of the β-fluorine couplings

The origin of the hyperfine couplings of β-fluorine nuclei in free radicals has been studied using the hyperfine tensors determined for and in single crystals. The direction of the maximum principal element of the β-fluorine coupling tensor in was found to be very close to the direction of the maximum overlap of the fluorine 2p π orbital with the half-filled carbon 2p π orbital. This means that the spin density in the fluorine 2p π orbital is mainly due to the direct overlap with the carbon 2p π orbital and the contributions from the hyperconjugation and the spin polarization mechanisms are less important. The cos²θ rule, B ₀ + B cos²θ, for the β-fluorine coupling tensor was also derived from the conformational dependence of the overlap integral. Using the ratio of B/B ₀ calculated from the overlap integral together with the observed hyperfine tensor for , the absolute values of B ₂ and B were determined and results were applied to the β-fluorine coupling tensor of the rotating CF₃ group in . The calculated tensor is in very good agreement with the one observed.