• Volume 73, Issue 5

November 2009,   pages  799-959

• Travelling wave solutions for a singularly perturbed Burgers–KdV equation

This paper concerns with the existence problem of travelling wave solutions to a singularly perturbed Burgers–KdV equation. For this, we use the dynamical systems approach, specifically, the geometric singular perturbation theory and centre manifold theory. We also numerically show approximations, in particular, for kink-type waves.

• On the discovery of the Greisen–Zatzepin–Kuzmin cut-off

The recent claim of the 5 sigma' observation of the Greisen–Zatzepin–Kuzmin cut-off by the HiRes group based on their nine years data is a significant step towards the eventual solution of one of the most intriguing questions in physics for more than 40 years. Recent results from Pierre Auger Observatory seem to confirm the statement. However, the word significance' is used in the mentioned paper in a sense which is not quite obvious. In the present paper we argue that this claim is a little premature.

• Do the generalized Fock-state wave functions have some relations with classical initial condition?

We examine whether the general type Fock-state wave functions for the harmonic oscillator have some relations with the classical initial condition.

• Intrinsic $g_{K}$ factors of odd-mass 167−179Lu isotopes

In this paper, $g_{K}$-factors of the intrinsic magnetic moments and effective spin gyromagnetic factors ($g_{s}^{\text{eff}}$) of the 167−179Lu isotopes have been studied within the Tamm–Dancoff approximation (TDA) (Kuliev et al, Sov. J. Nucl. Phys. 9, 185 (1969)) by using a realistic potential such as Woods–Saxon potential for the first time. The effects of the spin–spin and spin–isospin interactions on magnetic moments were investigated. The results of the theoretical calculations are compared with the experimental data for related nuclei. The experimental values of $g_{K}$ and $g_{s}^{\text{eff}}$ were computed from the observed magnetic moments (Georg et al, Eur. Phys. J. A3, 225 (1998)) using the spin matrix elements. The theoretical predictions for the g K factors exhibit good agreement with the experimental $g_{K}$ factors with increasing mass number A of the lutetium isotopes. The strongest influence of the neutron–proton spin interaction occurs at $q = −1$. Sufficient agreement between the calculated and the experimental values of $g_{K}$ is obtained for $κ = (45/A)$ MeV and $q = −1$.

• Temperature and angular momentum dependence of the quadrupole deformation in sd-shell

Temperature and angular momentum dependence of the quadrupole deformation is studied in the middle of the sd-shell for 28Si and 27Si isotopes using the spherical shell model approach. The shell model calculations have been performed using the standard universal sd-shell (USD) interaction and the canonical partition function constructed from the calculated eigensolutions. It is shown that the extracted average quadrupole moments show a transitional behaviour as a function of temperature and the infered transitional temperature is shown to vary with angular momentum. The quadrupole deformation of the individual eigenstate is also analysed.

• The neutron–proton pairing and the moments of inertia of the rare earth even–even nuclei

In this study, the possible effect of the neutron–proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even–even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.

• The influence of the nature of soil and plant and pollution on the 238U, 232Th, 222Rn and 220Rn concentrations in various natural honey samples using nuclear track detectors: Impact on the adult consumers

238U and 232Th concentrations as well as 222Rn and 220Rn 𝛼-activities per unit volume were measured in various natural honey samples collected from different regions in Morocco using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). These radionuclides were also measured in soils, plant flowers and nectar solutions corresponding to the honey samples studied. In addition, these radionuclides were measured in different imported honey samples. The measured 238U, 232Th, 222Rn and 220Rn concentrations ranged from $(1.5 \pm 0.1)$ mBq kg-1 to $(10.6 \pm 0.6)$ mBq kg-1, $(1.1 \pm 0.1)$ mBq kg-1 to $(4.2 \pm 0.2)$ mBq kg-1 , $(1.5 \pm 0.1)$ Bq kg-1 to $(10.6 \pm 0.6)$ Bq kg-1 and $(1.1 \pm 0.1)$ Bq kg-1 to $(4.2 \pm 0.2)$ Bq kg-1 for the honey samples studied, respectively. Annual 238U, 232Th and 222Rn intakes by Moroccan adults from the consumption of honey were assessed. The influence of the nature of soil and plant on the 238U and 232Th contents of the studied honey samples was investigated. These measurements were completed by an investigation of the 238U and 232 Th transfer between soils and plant flowers and that between plant flowers and honey, and also by the investigation of the influence of pollution due to different material dusts on 238U, 232Th and 222Rn in the honey samples studied. Committed equivalent doses due to the annual intake of 238U, 232Th and 222Rn were evaluated in the organs of adult members of the Moroccan rural population from the ingestion of the honey samples. The maximum total committed effective dose due to 238U, 232Th and 222Rn from the ingestion of natural honey by the Moroccan rural population was found to be equal to $0.64 \mu$ Sv y-1 .

• Vibrational spectrum of CF4 isotopes in an algebraic model

n this paper the stretching vibrational modes of CF4 isotopes are calculated up to first overtone using the one-dimensional vibron model for the first time. The model Hamiltonian so constructed seems to describe the C–F stretching modes accurately using a relatively small set of well-defined parameters.

• Vibrational analysis of Fourier transform spectrum of the $A^{3} \Pi_{0} –X^{1} \sum^{+}$ and $B^{3} \Pi^{1} –X^{1} \sum^{+}$ transitions of indium monobromide

The emission spectrum of InBr molecule has been recorded in the region 350–400 nm on BOMEM DA8 Fourier transform spectrometer at an apodized resolution of 0.06 cm-1 using microwave excitation technique. About 61 violet degraded and single headed bands have been recorded and are classified into two band systems, viz. $A^{3} \Pi_{0} –X^{1} \sum^{+}$ and $B^{3} \Pi_{1} –X^{1} \sum^{+}$. A few new bands have been observed and are fitted in the vibrational schemes of the two systems. Revised vibrational constants have been determined. The vibrational assignments have been confirmed by observing isotope effect due to InBr81 in the 30 bands of the $A^{3} \Pi_{0} –X^{1} \sum^{+}$ system and 19 bands of the $B^{3} \Pi_{1} –X^{1} \sum^{+}$ system. The analysis is further supported by calculating the Franck–Condon factor for InBr79 and InBr81 molecules. The following vibrational constants (in cm-1) have been determined from the analysis:

$$\begin{array}{llll}\text{A}^{3}\Pi_{0}-\text{X}^{1}\Sigma^{+} &amp; \text{system} &amp; v_{00}=26599.1 &amp; \omega'_{\text{e}} = 226.42, \ \omega'_{\text{e}}x'_{\text{e}}=1.24\text{~cm}^{-1},\\ &amp; &amp; &amp; \omega''_{\text{e}} = 221.19, \ \omega''_{\text{e}}x''_{\text{e}}=0.528\text{~cm}^{-1}.\\\text{B}^{3}\Pi_{1}-\text{X}^{1}\Sigma^{+} &amp; \text{system} &amp; v_{00}=27380.52 &amp; \omega'_{\text{e}}=223.086, \ \omega'_{\text{e}}x'_{\text{e}}=1.446\text{~cm}^{-1},\\ &amp; &amp; &amp; \omega''_{\text{e}}=221.19, \ \omega''_{\text{e}}x''_{\text{e}}=0.528\text{~cm}^{-1}. \end{array}$$

• Method of implementing frequency-encoded NOT, OR and NOR logic operations using lithium niobate waveguide and reflecting semiconductor optical amplifiers

Optics has already proved its strong potentiality for the conduction of parallel logic, arithmetic and algebraic operations. In the last few decades several all-optical data processors were proposed. To implement these processors different data encoding/decoding techniques have been reported. In this context, polarization encoding technique, intensity-based encoding technique, tristate and quaternary logic operation, multivalued logic operations, symbolic substitution techniques etc. may be mentioned. Very recently, frequency encoding/decoding technique has drawn interest from the scientific community. Frequency is the fundamental character of any signal; and it remains unaltered in reflection, refraction, absorption etc. during the propagation and transmission of the signal. This is the most important advantage of frequency encoding technique over the conventional encoding techniques. In this communication the authors propose a new scheme for implementing NOT, OR and NOR logic operations. For this purpose co-propagating beams having different frequencies in C-band (1535–1560 nm) have been used for generating cascaded sum and difference frequency, exploiting the nonlinear response character of periodically poled LiNbO3 waveguide. The cross-gain modulation property of the semiconductor optical amplifier (SOA) and the wavelength conversion property of the reflecting semiconductor optical amplifiers (RSOA) are exploited here to implement the desired optical logic and arithmetic operations.

• Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions

The Korteweg–de Vries–Burgers (KdV–Burgers) equation and modified Korteweg–de Vries–Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.

• Stacking faults and microstructural parameters in non-mulberry silk fibres

We have analysed the broadening of X-ray reflections observed in non-mulberry silk fibres in terms of stacking faults and microstructural parameters using a single-order method and have, with these parameters, developed, for the first time, a procedure to compute the whole pattern of these silk fibres. The essential deviations in the values of microstructural parameters obtained from line profile and whole pattern fitting procedures are discussed in this paper.

• Zero-field splitting and local structure for V2+ ions in CsMgX$_{3} (X=Cl, Br, I)$ crystals

The zero-field splitting and local structure for V2+ ions in CsMgX3 $(X = Cl, Br, I)$ crystals are theoretically investigated using complete diagonalization method (CDM) for a $3d^{3}$ ion in trigonal symmetry. Spin–spin (SS) and spin–other-orbit (SOO) interactions are taken into account in addition to the general spin–orbit (SO) interaction. On this basis, using ligand ion displacement model, we find that the ligand ions move away from $C_{3}$-axis, and therefore the local angles in the $V^{2+}$ centres are larger than the angles in the hosts. The results show good agreement with the observed values.

• Growth and high pressure studies of zirconium sulphoselenide single crystals

Transition metal trichalcogenides are well suited for extreme pressure lubrication. These materials being semiconducting and of layered structure may undergo structural and electronic transition under pressure. In this paper authors reported the details about synthesis and characterization of zirconium sulphoselenide single crystals. The chemical vapour transport technique was used for the growth of zirconium sulphoselenide single crystals. The energy dispersive analysis by X-ray (EDAX) gave the confirmation about the stoichiometry of the as-grown crystals and other structural characterizations were accomplished by X-ray diffraction (XRD) study. The variation of electrical resistance was monitored in a Bridgman opposed anvil set-up up to 8 GPa pressure to identify the occurrence of any structural transition. These crystals do not possess any structural transitions upto the pressure limit examined.

• The degree distribution of fixed act-size collaboration networks

In this paper, we investigate a special evolving model of collaboration net-works, where the act-size is fixed. Based on the first-passage probability of Markov chain theory, this paper provides a rigorous proof for the existence of a limiting degree distribution of this model and proves that the degree distribution obeys the power-law form with the exponent adjustable between 2 and 3.

• # Pramana – Journal of Physics

Current Issue
Volume 93 | Issue 5
November 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019