Open Access Published by De Gruyter Open Access

Volume 4 Issue 3

September 2006

Issue of Open Physics

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Open Access September 1, 2006

Rapidly rotating Bose-Einstein condensates in anharmonic confinement

Li-Hua Lu, You-Quan Li

Page range: 299-309

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Abstract

We study a rapidly rotating Bose-Einstein condensate in anharmonic confinement and find that many properties, such as the critical rotating frequency and phase diagram, are different from those in a harmonic trap. We investigate the phase transitions between various vortex lattices and find that a hole emerges in the center of the cloud when the rotating frequency Θ reaches Θh but it becomes invisible when Θ > 1.0842ω ⊥.

Open Access September 1, 2006

Ge diffusion on Si surfaces

Andrey Dolbak, Boris Olshanetsky

Page range: 310-317

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Abstract

Ge diffusion on Si(100), (111), and (110) surfaces has been studied by Auger electron spectroscopy and low energy electron diffraction in the temperature range from 600 to 800 °C. Surface diffusion coefficients versus temperature have been measured.

Open Access September 1, 2006

Shape-invariant hypergeometric type operators with application to quantum mechanics

Nicolae Cotfas

Page range: 318-330

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Abstract

A hypergeometric type equation satisfying certain conditions defines either a finite or an infinite system of orthogonal polynomials. The associated special functions are eigenfunctions of some shape-invariant operators. These operators can be analysed together and the mathematical formalism we use can be extended in order to define other shape-invariant operators. All the shape-invariant operators considered are directly related to Schrödinger-type equations.

Open Access September 1, 2006

Simulating a perpendicular exchange-biased structure with a partially covering nonmagnetic insertion at the FM/AFM interface

Tomasz Błlachowicz

Page range: 331-340

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Abstract

The existence of minority spins, opposite to the perpendicular exchange bias, and majority spins aligned with this bias, and the dependence of the perpendicular exchange-bias field on the imprint effect, caused by the partially covering spacer at the ferromagnetic/antiferromagnetic (FM/AFM) interface, have been studied using Ising-type simulations. The present investigation suggests that the main factors influencing this phenomenon were dependent on the FM/AFM interface morphology, the balance between FM/AFM coupling and the FM-spins coupling, and the numerical balance between minority and majority spins. It was also determined that the imprint phenomenon can be used to enhance the perpendicular exchange-bias for small partial insertions at the FM/AFM interface.

Open Access September 1, 2006

Development of temporal spectroscopic properties for Xerogel matrices doped with Rhodamine 6G dye

Abbas Al-Wattar, Baha Chiad, Wesam Twej, Sarmed Al-Awadi

Page range: 341-348

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Abstract

The solid host of a laser dye modifies its spectroscopic properties with respect to its liquid host. During the Sol-Gel process the dye molecules suffer from changing their environment. Two parameters affect this matter, the change in the concentration due to the evaporation of the solvent (drying) and the caging of dye molecules inside the pores or attachment to the silica network. Rhodamine 6G absorption and fluorescence spectra with different concentrations, during Sol-Gel time processing, have been studied. Both, absorption and fluorescence spectra of the dye in the solid host, for different concentrations, show a blue-shift relative to its liquid phase.

Open Access September 1, 2006

Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction

Kamil Walczak

Page range: 349-362

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Abstract

Here we present the calculations of incoherent current flowing through the two-site molecular device as well as the DNA-based junction within the rate-equation approach. Selected phenomena of interest are discussed in detail. The structural asymmetry of a two-site molecule results in a rectification effect, which can be neutralized by an asymmetric voltage drop at the molecule-metal contacts due to coupling asymmetry. The results received for the poly(dG)-poly(dC) DNA molecule reveal the coupling-and temperature-independent saturation effect of the current at high voltages, establishing for short chains the inverse square distance dependence. Additionally we document the conductance peak shifting in the direction of higher voltages due to a temperature decrease.

Open Access September 1, 2006

Lévy-statistics for partially equilibrated systems

Athanasios Petridis

Page range: 363-368

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Abstract

We examine deviations from Boltzmann-Gibbs statistics for a certain class of partially equilibrated systems of finite size. We find that such systems are characterized by the Lévy distribution whose non-extensivity parameter is related to the number of internally equilibrated subsystems and to correlations among them. This concept is applicable to relativistic heavy ion collisions.

Open Access September 1, 2006

Radial distribution of hydrogen atoms in H 2 plasma

Slavoljub Mijović, Mira Vučeljić

Page range: 369-379

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Abstract

The radial intensities of the H α and H 2 Fulcher α (d 3Πu − a 3Σg) system spectral lines were used to obtain the radial distribution of hydrogen atoms in H 2 plasma discharge. We have obtained new equations in order to describe the distribution of atoms in molecule discharges. Abel’s integral equation has been solved by Tikhonov’s regularization procedure. Model functions have been introduced to examine the limitations in the applicability of this method. An estimation of the degree of dissociation in the radial direction has been obtained.

Open Access September 1, 2006

Quantum states with Space-like energy-momentum

Dan Solomon

Page range: 380-392

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Abstract

A common assumption in quantum field theory is that the energy-momentum 4-vector of any quantum state must be time-like. It will be proven that this is not the case for a Dirac-Maxwell field. In this case quantum states can be shown to exist whose energy-momentum is space-like.

Open Access September 1, 2006

Small damping approach in Fermi-liquid theory

Volodymyr Kolomietz, Sergiy Lukyanov, Shalom Shlomo

Page range: 393-404

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Abstract

The validity of the small damping approximation (SDA) for the quasi-classical description of the averaged properties of nuclei at high temperatures is studied within the framework of collisional kinetic theory. The isoscalar collective quadrupole vibrations in hot nuclei are considered. We show that the extension of the SDA, by accounting for the damping of the distribution function δ f in the collision integral, reduces the rate of variation of distortion effects of the Fermi surface with temperature. The damping of the δ f in the collision integral increases the collisional width of the giant quadrupole resonance (GQR) significantly for small enough values of the relaxation time. The temperature dependence of the eigenenergy of the GQR becomes much weaker than in the corresponding SDA case.

Open Access September 1, 2006

A virtual instrumentation based protocol for the automated implementation of the inner field compensation method

Loredana Mereuta, Tudor Luchian

Page range: 405-416

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Abstract

One influential parameter which mediates interactions between many types of molecules and biological membranes stems from the lumped contributions of the transmembrane potential, dipole potential and the difference in the surface potentials on both sides of a membrane. With relevance to cell physiology, such electrical features of a biomembrane are prone to undergoing changes as a result of interactions with the aqueous surrounding. Among the most useful tools devoted to exploring changes of electrical parameters of a lipid membrane induced by certain extracellular ions, lipid composition, and embedded membrane peptides and proteins, are spectroscopic imaging and the inner field compensation (IFC) method. In this work we layout the principles of a fully computerized version of the IFC method, which makes it more readily available to users. As a direct application, we deployed this improved version of the IFC method to time-resolve changes induced by alamethicin monomers upon membrane dipole potential, following their aggregation within an artificial lipid membrane. Intriguingly, even prior crossing the membrane core, the membrane-bound alamethicin monomers are shown to significantly increase the dipole potential of the monolayer they reside in. Such data further emphasize the yet less-explored interplay between membrane-based protein and peptides, and the membrane dipole potential.

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Open Physics is a peer-reviewed, open access, electronic journal devoted to the publication of fundamental research results in all fields of physics. The journal provides the readers with free, instant, and permanent access to all content worldwide; and the authors with extensive promotion of published articles, long-time preservation, language-correction services, no space constraints and immediate publication.
Open Physics is listed inter alia by Clarivate Analytics (formerly Thomson Reuters) - Current Contents/Physical, Chemical and Earth Sciences, JCR and SCIE. Our standard policy requires each paper to be reviewed by at least two Referees and the peer-review process is single-blind.

Special / Topical Issues:

Special Issue on Predicting Patern Alterations in Nature
Guest Editors:
Prof. Abdon Atangana, University of the Free State, South (Lead Guest Editor)
Prof. Dr. Emile Franc Goufo, University of South Africa
Prof. Dr Seda İğret Araz, Siirt University, Turkey

The journal publishes research and review articles, rapid and short communications, comments and replies that cover the following areas of physical sciences:

Acoustics
Astrophysics,
Atomic and Molecular Physics,
Biological and Medical Physics,
Complex Networks, Socio- and Econophysics,
Computational Physics,
Condensed Matter Physics,
Cosmology and Gravitation,
Fluid Mechanics,
Geophysics,
Nanophysics,
Optics and Lasers,
Particle and Nuclear Physics,
Plasma Physics,
Statistical and Nonlinear Physics,
Surface Physics,
Theoretical and Mathematical Physics.

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