Stationary Nuclei Research Articles

Nonlinear coherent structures of nucleus-acoustic wave excitations in multi-nuclei quantum plasmas with ultra-relativistically degenerate electrons and positrons

The propagation dynamics of the nucleus-acoustic waves (NAW) in a quantum plasma composed of nondegenerate inertial light nuclei, stationary heavy nuclei, and ultra-relativistically degenerate electrons and positrons has been theoretically investigated within the framework of the Boussinesq equation, which is valid for a bi-directional propagation of a small but finite amplitude limit. The N-soliton solution of the Boussinesq equation is derived using Hirota's method. It is found that positive potential structures exist in the sonic and supersonic regimes, whereas negative potential structures are found to be present in the subsonic regime. Pertinent plasma properties are analyzed for one-, two-, and three-soliton solutions in terms of different parameters. In addition to the typical solitary wave solutions, our findings indicate that the nonlinear NAW has breather structures. The three- and four-soliton solutions are used to construct the elastic interaction solutions of the breather–soliton and breather–breather, respectively. The findings are discussed in the context of ultra-relativistic astrophysical plasmas.

Roles of degenerate quantum plasma temperature and stationary heavy nucleus species in nucleus-acoustic shock waves

The warm degenerate plasma model (on the basis of warm degenerate inertialess electron species, warm dissipative inertial light nucleus species, and stationary heavy nucleus species) is considered. The effects of degenerate plasma temperature and stationary heavy nucleus species on the basic features of cylindrical and spherical nucleus-acoustic shock waves propagating in such a warm degenerate plasma system are investigated. The reductive perturbation method (which is valid for small amplitude shock waves) and special stretched co-ordinates (which corresponds to the omission of the dispersion effect, and is appropriate for the monotonic shock waves) are employed. The kinematic viscous force acting in the light nucleus fluid is the only source of dissipation, and is responsible for the formation of monotonic shock waves. It is observed that the basic features of these monotonic shock waves are significantly modified by the effects of degenerate plasma temperature, ultra-relativistically degenerate electron species, and stationary heavy nucleus species. The applications of this new plasma model (defined by generalized Chandrasekhar equation of state which is also valid for finite temperature) in the cold, as well as hot white dwarfs are addressed.

Nonclassical trajectories in head-on collisions

Rutherford scattering is usually described by treating the projectile either classically or as quantum mechanical plane waves. Here we treat them as wave packets and study their head-on collisions with the stationary target nuclei. We simulate the quantum dynamics of this one-dimensional system and study deviations of the average quantum solution from the classical one. These deviations are traced back to the convexity properties of Coulomb potential. Finally, we sketch how these theoretical findings could be tested in experiments looking for the onset of nuclear reactions.

Planar and non-planar nucleus-acoustic solitary waves in warm degenerate multi-nucleus plasmas

A warm degenerate plasma (containing ultra-relativistically or non-relativistically warm degenerate inertia-less electron species, non-relativistically warm degenerate inertial light nucleus species and stationary heavy nucleus species) is considered. The basic features of planar and non-planar solitary structures associated with the degenerate pressure-driven nucleus-acoustic waves propagating in such a warm degenerate plasma system are investigated. The reductive perturbation method, which is valid for small- but finite-amplitude solitary waves, is used. It is found that the effects of non-planar cylindrical and spherical geometries, non- and ultra-relativistically degenerate electron species and the temperature of degenerate electron species significantly modify the basic features (i.e. speed, amplitude and width) of the solitary potential structures associated with degenerate pressure-driven nucleus-acoustic waves. The warm degenerate plasma model under consideration is applicable not only to all cold white dwarfs, but also to many hot white dwarfs, such as DQ white dwarfs, white dwarf H1504+65, white dwarf PG 0948+534, etc.

Subsonic and supersonic nucleus-acoustic solitary waves in thermally degenerate multi-nucleus plasma systems

A new thermally degenerate multi-nucleus plasma system (containing thermally degenerate electron species, non-degenerate warm light nucleus species, and low dense stationary heavy nucleus species) is considered. The basic features of arbitrary amplitude subsonic and supersonic solitary waves associated with thermally degenerate pressure-driven nucleus-acoustic waves in such a plasma system are studied by the pseudo-potential approach. The effects of the stationary heavy nucleus, non- and ultra-relativistically degenerate electron degeneracies, and light nucleus temperature on such arbitrary amplitude subsonic and supersonic solitary waves are also examined. It is found that (i) the presence of the heavy nucleus and Boltzmann distributed electron species supports the existence of subsonic solitary waves and the effects of electron degeneracies and light nucleus temperature reduce the possibility for the formation of these subsonic solitary waves; (ii) the amplitude (width) of these subsonic solitary waves increases (decreases) with the increase in the number density of the heavy nucleus species; (iii) the amplitude of the supersonic solitary waves in the situation of non-relativistically degenerate electron species is much smaller than that of the ultra-relativistically degenerate electron species but is much larger than that of the Boltzmann distributed electron species; (iv) their width in the situation of non-relativistically degenerate electron species is much wider than that of the ultra-relativistically degenerate electron species; and (v) their amplitude (width) decreases (increases) with the increase in the light nucleus temperature. The applications of the results in some degenerate astrophysical plasma systems and non-degenerate space plasma environments are discussed.

Populating high spin states of a compound nucleus with the incomplete fusion mechanism: the effectiveness of heavy projectiles

Using a classical dynamical reaction model, angular momentum (L) values of a compound nucleus due to incomplete fusion (ICF) at energies near and above the Coulomb barrier are studied. In this model, a projectile consisting of two cluster nuclei is fired at a stationary target nucleus. After breakup of the projectile due to Coulombic and nuclear forces, an α-cluster fuses with a 208Pb target, forming an excited 212Po compound nucleus. Results show that all ICF reactions produced higher angular momentum in the compound nucleus compared to a direct beam of α particles at the same incident energy. The highest angular momentum values produced in 212Po for near and above Coulomb barrier energies were obtained using a 20Ne projectile at and , respectively. This produced 25% and 50% L values above the next highest-Z projectile used, 8Be, respectively.

A potential justifying superconductivity and pseudogap formation in high-Tc superconductors

Copper and Iron based high temperature superconductors exhibit d-wave type superconducting gap and order parameter and posses a universal phase diagram. Here a potential is introduced that accounts for high temperature superconductivity, justifies d-wave symmetric behavior, and successfully explains phase diagram’s salient features. This potential is stipulated by principles of special relativity and arises from the difference between the electric potential of moving electrons and the potential of stationary nuclei. In quasi-two-dimensional materials this difference results in an uncompensated angular dependent attraction force in preferred directions of motion and a repulsion force in the perpendicular directions. The attraction force causes d-wave angular dependent superconducting gap and order parameter at high temperatures for d or p orbitals, which are the orbitals involved in Copper and Iron based superconductors. The repulsion force justifies the existence of angular dependent pseudogap and since the attraction and repulsions forces confine electrons to two directions of motion the number of allowed momentum states are reduced resulting in anti-ferromagnetic Mott-insulator behavior. The combination of the attraction and repulsion forces is shown to create charge density waves in these quasi-two-dimensional materials. This potential is able to justify the main features of the universal phase diagram self-consistently.

Nucleus-acoustic solitary waves in white dwarfs

The formation of nucleus-acoustic solitary waves (NASWs), and their basic properties in white dwarfs containing non-relativistically or ultra-relativistically degenerate electrons, non-relativistically degenerate light nuclei, and stationary heavy nuclei have been theoretically investigated. The reductive perturbation method, which is valid for small but finite amplitude NASWs, is used. The NASWs are, in fact, associated with the nucleus acoustic (NA) waves in which the inertia is provided by the light nuclei, and restoring force is provided by the degenerate pressure of electrons. On the other hand, stationary heavy nuclei maintain the background charge neutrality condition. It has been found that the presence of the heavy nuclei significantly modify the basic features (polarity, amplitude, width, and speed) of the NASWs. The basic properties are also found to be significantly modified by the effects of ultra-relativistically degenerate electrons and relative number densities of light and heavy nuclei. The implications of our results in white dwarfs are pinpointed.

Linear Nuclear Acoustic Waves in Degenerate Quantum Plasma

A rigorous theoretical investigation has been made on the linear propagation of electrostatic perturbation modes of degenerate pressure driven modified nucleus-acoustic (DPDMNA) ‘waves in a degenerate quantum plasma (DQP) system. It contains cold inertia-less degenerate electron species (DES), cold inertial non-degenerate light nucleus species (LNS) and stationary heavy nucleus species (HNS) which maintains the quasi-neutrality condition at equilibrium only. The mass density of the cold LNS provides the inertia and the cold inertia-less cold LNS provides the inertia and the cold inertia-less DES gives rise to the restoring force. The reductive perturbation method has been used for the study of nonlinear propagation of the DPDMNA waves. The basic features of linear waves are supervised in a theoretical manner. It has been observed that the phase speed of DPDMNA waves changes with the change of charge density of the stationary HNS for both non-relativistic and ultra-relativistic DES; The NA waves with their dispersion properties which are consequential in various astrophysical and laboratory plasmas, have been broadly considered.
 GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 5(1), Dec 2018 P 20-23

Nucleus-acoustic shock waves in white dwarfs

The nucleus-acoustic shock waves (NASWs) propagating in a white dwarf plasma system, which contain non-relativistically or ultrarelativistically degenerate electrons, non-relativistically degenerate, viscous fluid of light nuclei, and immobile nuclei of heavy elements, have been theoretically investigated. We have used the reductive perturbation method, which is valid for small but finite-amplitude NASWs to derive the Burgers equation. The NASWs are, in fact, associated with the nucleus-acoustic (NA) waves in which the inertia is provided by the light nuclei, and restoring force is provided by the degenerate pressure of electrons. On the other hand, the stationary heavy nuclei participate only in maintaining the background charge neutrality condition at equilibrium. It is found that the viscous force acting in the fluid of light nuclei is a source of dissipation, and is responsible for the formation of NASWs. It is also observed that the basic features (polarity, amplitude, width, etc.) of the NASWs are significantly modified by the presence of heavy nuclei, and that NASWs are formed with either positive or negative potential depending on the values of the charge density of the heavy nuclei. The basic properties are also found to be significantly modified by the effects of ultrarelativistically degenerate electrons. The implications of our results in white dwarfs are briefly discussed.

Robustness of expression pattern formation due to dynamic equilibrium in gap gene system of an early Drosophila embryo

The first manifestation of a segmentation pattern in the early Drosophila development is the formation of expression domains of genes belonging to the gap class. In our previous research the phenomenon of the gap system’s robustness, exhibited as the ability to reduce highly variable gene expression in the course of development, was explained as a result of gene cross-regulation. In this paper we formulate the rigorous robustness conditions using the inherent properties of gap gene family.We propose an approach based on the observation that for the formation of a pattern with well-established domain borders it is necessary that there exist a stationary nucleus in which the gene expression level is almost constant in time. The dynamics of gap gene expression is described by a gene circuit model that correctly reproduces the observed principles of the border positioning.We take an advantage of the fact that the system behavior in a stationary nucleus is described by an algebraic equation and hence can be easily handled analytically. This enables us to explicitly characterize the gene cross-regulation properties guaranteeing the system robustness through the spatial behavior of the patterning system along the main embryo axis. In particular, it is proved that if the total regulatory action of all the genes acting in the border formation area changes synchronously with the initial gene gradient, the system will filtrate the initial positioning error and action of highly variable external input factors.We will now show how this approach can be applied as an instrument for the analysis of the robustness mechanism and revealing new biological findings.

Arbitrary amplitude nucleus-acoustic solitons in multi-ion quantum plasmas with relativistically degenerate electrons

A three component degenerate relativistic quantum plasma (consisting of relativistically degenerate electrons, nondegenerate inertial light nuclei, and stationary heavy nuclei) is considered to model the linear wave and also the electrostatic solitary waves in the light nuclei-scale length. A well-known normal mode analysis is employed to investigate the linear wave properties. A mechanical-motion analog (Sagdeev-type) pseudo-potential approach, which reveals the existence of large amplitude solitary excitations, is adopted to study the nonlinear wave properties. Only the positive potential solitary excitations are found to exist in the plasma medium under consideration. The basic properties of the arbitrary amplitude electrostatic acoustic modes in the light nuclei-scale length and their existence domain in terms of soliton speed (Mach number) are examined. The modifications of solitary wave characteristics and their existence domain with the variation of different key plasma configuration parameters (e.g., electrons degeneracy parameter, inertial light nuclei number density, and degenerate electron number density) are also analyzed. Our results, which may be helpful to explain the basic features of the nonlinear wave propagation in multi-component degenerate quantum plasmas, in connection with astrophysical compact objects (e.g., white dwarfs) are briefly discussed.

Degenerate pressure driven modified nucleus-acoustic waves in degenerate plasmas

The existence of degenerate pressure driven modified nucleus-acoustic (DPDMNA) waves propagating in a cold degenerate quantum plasma (DQP) system [containing cold inertialess degenerate electron species (DES), cold inertial non-degenerate light nucleus species (LNS), and stationary heavy nucleus species (HNS)] is predicted for the first time. The DPDMNA waves (in which the mass density of the cold LNS provides the inertia and the cold inertialess DES gives rise to the restoring force) are new since they completely disappear if the degenerate pressure of the cold DES is neglected. It is found that the phase speed (Vp) of the DPDMNA waves decreases with the rise of the charge number density of the stationary HNS for both non-relativistic and ultra-relativistic DES, and that the ultra-relativistic DES does not have any effect on Vp when β = 1, where β = Λc/Λe with Λe=ne0−1/3 being the average inter-electron distance in the DQP system and Λc being the constant (∼10−10 cm) for the DES. However, the ultra-relativistic DES does have quite a significant effect on Vp for β ≫ 1 and β ≪ 1, and the ultra-relativistic effect significantly enhances (reduces) Vp for β ≫ 1 (β ≪ 1). The DPDMNA waves and their dispersion properties are expected to be useful in understanding the basic features of the electrostatic perturbation mode in space and laboratory DQP systems.

THE CHARACTERISTICS OF ELECTRON-NUCLEAR MODEL IN THE DEGENERATE DWARFS THEORY. EQUATION OF STATE

Within the microscopic theory the ground state energy of spatially homogeneous degenerate relativistic subsystem of electrons in the field of stationary nuclei of l-th sorts with charges z1, . . . , zl was calculated. In the two- and three-particle electron correlations approximation the contributions of Coulomb interactions to the equation of model state at low temperatures was analyzed.

Envelope solitons in three-component degenerate relativistic quantum plasmas

The criteria for the formation of envelope solitons and their basic features in a three-component degenerate relativistic quantum plasma (DRQP) system (containing relativistically degenerate electrons, non-degenerate inertial light nuclei, and stationary heavy nuclei) are theoretically investigated. The nonlinear Schrödinger equation is derived by employing the multi-scale perturbation technique. The envelope solitons are found to be associated with the modified ion-acoustic waves in which the inertia (restoring force) is provided by the mass density of light nuclei (degenerate pressure of cold electrons). The basic features of these envelope solitons, which are found to formed in such a DRQP system, and their modulational instability criteria (on the basis of the plasma parameters associated with the degenerate pressure of electrons, number densities of degenerate electrons, inertial light nuclei, and stationary heavy nuclei) are identified. The numerical simulations are also performed to confirm the stability of the envelope solitons predicted here by analytical analysis.

Understanding Nonradiative Recombination through Defect-Induced Conical Intersections.

Defects are known to introduce pathways for the nonradiative recombination of electronic excitations in semiconductors, but implicating a specific defect as a nonradiative center remains challenging for both experiment and theory. In this Perspective, we present recent progress toward this goal involving the identification and characterization of defect-induced conical intersections (DICIs), points of degeneracy between the ground and first excited electronic states of semiconductor materials that arise from the deformation of specific defects. Analysis of DICIs does not require the assumption of weak correlation between the electron and hole nor of stationary nuclei. It is demonstrated that in some cases an energetically accessible DICI is present even when no midgap state is predicted by single-particle theories (e.g., density functional theory). We review recent theoretical and computational developments that enable the location of DICIs in semiconductor nanomaterials and present insights into the photoluminescence of silicon nanocrystals gleaned from DICIs.

On the Coulomb effect in laser-assisted proton scattering by a stationary atomic nucleus

In the framework of the first Born approximation, we investigate the scenario where in addition to a laser field, a nuclear Coulomb field is also present to affect a proton. We work in the approximation in which the proton is considered to be a structureless spin 1/2 Dirac particle with a mass mp. Furthermore, in the laboratory system, the fixed nucleus is treated as a point-like Coulomb potential. In the presence of a laser field, and taking into account the Coulomb effect, the proton will be described by distorted Dirac–Volkov wave functions. The introduction of the Coulomb effect to both the incident and scattered proton will enhance the relativistic differential cross sections (RDCSs). Regarding the physical picture, it is found that for the various kinetic energies of the incident proton, the Coulomb effect can be neglected at high kinetic energies in this particular geometry. Therefore, Dirac–Volkov states are largely sufficient to describe the laser-dressed protons. The behavior of the various RDCSs versus the atomic number Z is also presented.

Analisis Time Repetition (TR) dan Flip Angle (FA) terhadap Informasi Anatomi pada Pemeriksaan 3D TOF MRA Brain dengan MRI 1.5 Tesla

Background: In brain MR angiography examination, there are many clinical situations where the radiologist want to optimal suppression of stasionary nuclei. So stationary nuclei and flowing nuclei will produce a good contrast. One of the most commonly used method brain MR angiography o is a 3D TOF because it can show the blood vessels by hyperintens with more hypointens of background. Parameters TR and flip angle is one of the parameters that will determine a stationary nuclei experiencing well suppression and the flowing nuclei will still generate a signal that more hyperintens. The purpose of this study is to determine the influence of time repetition and flip angle of the anatomical information of 3D TOF brain MRA examination, and also to determine value the time repetition and flip angle best to display anatomical information of 3D TOF brain MRA examination.Methods: This research is an experimental approach to the pre-experimental research design and post-test only research design. This research was conducted in Bintaro Premier Hospital. The data in the form of 54 3D TOF brain MRA images of 6 volunteers with nine variations time repetitions and flip angle. Assessment anatomical information performed by the two respondents. The data analysis by testing the influence is multiple linear regression to determine the value of time repetition and flip angle optimal use Friedman mean rank test.Result: The result showed that there is the influence of time repetition and flip angle of the anatomical information on 3D TOF brain MRA examination with a significance value p 0.001 (p 0.05). The time repetition 30 ms and flip angle 30o is and optimal value for anatomical information showing 3D TOF brain MRA examination. Application of time repetition 30 ms and flip angle 30o can be properly saturate or suppression the stationary nuclei so that is displays excellent contrast between the nuclei. Conclution: There are influence of time repetition and flip angle to anatomical information of 3D TOF brain MRA examination with a significance value of p 0.001 (p 0.05). The time repetition 30 ms and a flip angle of 30o is an optimal value for anatomical information showing 3D TOF brain MRA examination.

Dynamics of condensate formation in stochastic transport with pair-factorized steady states: Nucleation and coarsening time scales.

Driven diffusive systems such as the zero-range process (ZRP) and the pair-factorized steady states (PFSS) stochastic transport process are versatile tools that lend themselves to the study of transport phenomena on a generic level. While their mathematical structure is simple enough to allow significant analytical treatment, they offer a variety of interesting phenomena. With appropriate dynamics, the ZRP and PFSS models feature a condensation transition where, for a supercritical density, the translational symmetry breaks spontaneously and excess particles form a single-site or spatially extended condensate, respectively. In this paper we numerically study the typical time scales of the two stages of this condensation process: Nucleation and coarsening. Nucleation is the first stage of condensation where the bulk system relaxes to its stationary distribution and droplet nuclei form in the system. These droplets then gradually grow or evaporate in the coarsening regime to coalesce in a single condensate when the system finally relaxes to the stationary state. We use the ZRP condensation model to discuss the choice of the estimation method for the nucleation time scale and present scaling exponents for the ZRP and PFSS condensation models with respect to the choice of the typical droplet nuclei mass. We then proceed to present scaling exponents in the coarsening regime of the ZRP for partially asymmetric dynamics and the PFSS model for symmetric and asymmetric dynamics.

Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements

The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.