Far-from-equilibrium initial conditions probed by a nonlocal observable

Using the gauge/gravity duality, we investigate the evolution of an out-of-equilibrium strongly-coupled plasma from the viewpoint of the two-point function of scalar gauge-invariant operators with large conformal dimension. This system is out of equilibrium due to the presence of anisotropy and/or a massive scalar field. Considering various functions for the initial anisotropy and scalar field, we conclude that the effect of the anisotropy on the evolution of the two-point function is considerably more than the effect of the scalar field. We also show that the ordering of the equilibration time of the one-point function for the non-probe scalar field and the correlation function between two points with a fixed separation can be reversed by changing the initial configuration of the plasma, when the system is out of the equilibrium due to the presence of at least two different sources like our problem. In addition, we find the equilibration time of the two-point function to be linearly increasing with respect to the separation of the two points with a fixed slope, regardless of the initial configuration that we start with. Finally we observe that, for larger separations the geodesic connecting two points on the boundary crosses the event horizon after it has reached its final equilibrium value, meaning that the two-point function can probe behind the event horizon

THE UTILIZATION OF THORIUM-232 IN ADVANCED PWR – FROM SMALL TO BIG REACTORS

Since the beginning of Nuclear Energy Development, thorium was considered as a potential fuel, mainly due to the potential to produce fissile 233U. Several Th/U fuel cycles, using thermal and fast reactors were proposed and are still under investigation. However, the technical feasibility to use thorium was made in PWR; the USA PWR Indian Point Reactor was the first to utilize a core load with (Th0-0.9./U1-0.1)O2, with highly enriched U (93 w/0), achieving a maximum burn up of 32 MWD/kg HM. Also the last core of the Shipping port PWR (shutdown in 1982) was ThO2 and (Th/U)O2, operating as a Light Water Breeder Reactor (Seed- Blanket Concept) during 1200 effective full power days of operation (60 MWD/kg HM). More recently, many researchers turned their attention to Th fuel cycles in PWRs aiming at reducing the generation of minor actinide waste, at improving the nuclear power sustainability and at better fuel utilization. These studies were interested in assessing the feasibility of using 233U-Th fuels in PWR without worrying about how to obtain the initial 233U fuel load or the transition from an uranium to a thorium core in the current nuclear power plants. In this paper a review of the recent initiatives to utilize mixed oxide of U-Th in PWR is going to be provided, with an emphasis in two types of Advanced Reactors, the first a Small Modular Reactor (SMR); and the second a Generation III Advanced PWR (APWR). For the SMR, we use as criteria the fact that the core is designed to stand for a complete cycle, without the need to be refueled, but they need to be strongly poisoned at the beginning of life. So, since thorium can be used as a poison and a fertile fuel it could be a good option to be used as mixed oxide with uranium, and so we could reduce the burnable poison and have an extended burnup cycle. For the APWR, we use as criterion that the transition from the current UO2 APWR core to one with mixed U/Th fuels should be such that minimum changes occur on its current core design and operational parameters. Thus, one could consider the following requirements in this study: produce important amounts of 233U (maximization) for future 233U/Th cores; keep the current fuel assembly geometry, i.e., fuel rod diameter and pitch and meet the current thermal-hydraulic limits such as maximum center line fuel rod temperature and maximum linear power density; keep the current fuel cycle length of 18 months. As case studies, for the SMR, we used the Korean SMART reactor (the first integrated PWR to receive design certification), and for the APWR we used the Westinghouse AP 1000, due to its commercial success, with units being constructed in the USA and China. For both reactors we used a parametric study using homogeneous and heterogeneous fuel assemblies keeping the same geometry as the original UO2 core, and just changing the pellet material for (U-Th) O2. All the calculations were made by Monte Carlo codes. The results for both reactors show the feasibility to utilize thorium and satisfying the criterium imposed, even with advantages such as an extended discharge burn up, reducing the burn up poison, and a lower linear power density. As conclusion, we notice that the utilization of thorium in small or big PWR could be done successfully, without needing any changes in the current Nuclear Power Plants

Nonlinear Excitations in Strongly-Coupled Fermi-Dirac Plasmas

In this paper we use the conventional quantum hydrodynamics (QHD) model in combination with the Sagdeev pseudopotential method to explore the effects of Thomas-Fermi nonuniform electron distribution, Coulomb interactions, electron exchange and ion correlation on the large-amplitude nonlinear soliton dynamics in Fermi-Dirac plasmas. It is found that in the presence of strong interactions significant differences in nonlinear wave dynamics of Fermi-Dirac plasmas in the two distinct regimes of nonrelativistic and relativistic degeneracies exist. Furthermore, it is remarked that first-order corrections due to such interactions (which are proportional to the fine-structure constant) are significant on soliton dynamics in nonrelativistic plasma degeneracy regime rather than relativistic one. In the relativistic degeneracy regime, however, these effects become less important and the electron quantum-tunneling and Pauli-exclusion dominate the nonlinear wave dynamics. Hence, application of non-interacting Fermi-Dirac QHD model to study the nonlinear wave dynamics in quantum plasmas such as compact stars is most appropriate for the relativistic degeneracy regime

Transdiagnostic treatment of co-occurrence of anxiety and depressive disorders based on repetitive negative thinking: A case series

Objective: The transdiagnostic cognitive behavioral treatments for treating the coexistence of anxiety and mood disorders received useful empirical supports in the recent years. However, these treatments still have moderate efficacy. Following the improvements and developments in transdiagnostic protocols and considering the importance of repetitive negative thinking as a core transdiagnostic factor in emotional disorders, this study examined a new form of transdiagnostic treatment based on Repetitive Negative Thinking (TTRNT) of co-occurrence of anxiety and depressive disorders. Methods: Treatment efficacy was assessed using single case series with multiple baselines. Three patients meeting the criteria for co-occurrence of anxiety and depressive disorders were selected using the Anxiety Disorders Interview Schedule for DSM-IV. The patients were treated individually for 12 weekly sessions. Participants completed the standardized outcome measures during the baseline, treatment and one-month follow-up. Results: At post-treatment, all participants showed significant clinical changes on a range of standardized outcome measures, and these gains were largely maintained through the one-month follow-up both in the principle and co-principal diagnosis. Conclusions: Although the results of this preliminary investigation indicated that TTRNT could be a time effective and efficient treatment for individuals with co-occurrence of anxiety and depressive disorders, further controlled clinical trials are necessary to examine this new treatment approach

Quantum collapse in ground-state Fermi-Dirac-Landau plasmas

It is revealed that in a relativistically degenerate dense highly-magnetized electron-ion plasma the effective quantum-potential due to the total quantum-force acting on fermions may cancel-out causing a quantum transverse collapse in the ground-state Fermi-Dirac-Landau (GSFDL) plasma. The condition for the plasma transverse collapse is found to be restricted to the minimum relativistic degeneracy parameter and minimum impressed magnetic field strength values satisfied for many superdense astrophysical objects such as white dwarfs and neutron stars. In such plasmas, the magnetization pressure is shown to cancel the lateral electron degeneracy pressure counteracting the existing gravitational pressure. Furthermore, using the Sagdeev pseudopotential method in the framework of quantum magnetohydrodynamics (QMHD) model including spin magnetization it is confirmed that the quantum pressure due to spin-orbit polarization and the electron relativistic degeneracy has significant effects on the existence criteria and the propagation of localized magnetosonic density excitations in GSFDL plasmas. Current findings can have important implications for the density excitations mechanism and gravitational collapse of the highly magnetized astrophysical relativistically dense objects such as white-dwarfs, neutron stars, magnetars and pulsars.Comment: To be Published in Journal Physics of Plasma

Orbital Ferromagnetism and Quantum Collapse in Stellar Plasmas

The possibility of quantum collapse and characteristics of nonlinear localized excitations is examined in dense stars with Landau orbital ferromagnetism in the framework of conventional quantum magnetohydrodynamics (QMHD) model including Bohm force and spin-orbit polarization effects. Employing the concepts of effective potential and Sagdeev pseudopotential, it is confirmed that the quantum collapse and Landau orbital ferromagnetism concepts are consistent with the magnetic field and mass-density range present in some white dwarf stars. Furthermore, the value of ferromagnetic-field found in this work is about the same order of magnitude as the values calculated earlier. It is revealed that the magnetosonic nonlinear propagations can behave much differently in the two distinct non-relativistic and relativistic degeneracy regimes in a ferromagnetic dense astrophysical object. Current findings should help to understand the origin of the most important mechanisms such as gravitational collapse and the high magnetic field present in many compact stars.Comment: To appear in journal Physics of Plasma

Orbital Ferromagnetism and the Chandrasekhar Mass-Limit

In this paper, using both quantum magnetohydrodynamic (MHD) and magnetohydrostatic (MHS) models of a relativistically degenerate magnetic compact star, the fundamental role of Landau orbital ferromagnetism (LOFER) on the magneto-gravitational stability of such star is revealed. It is shown that the previously suggested magnetic equation of state for LOFER with some generalization of form $B=\beta \rho^{2s/3}$ only within the range $0\leq s\leq 1$ and $0\leq \beta< \sqrt{2\pi}$ leads to magneto-gravitational stability with distinct critical value $\beta_{cr}=\sqrt{2\pi}$ governing the magnetohydrostatic stability of the compact star. Furthermore, the value of the parameters $s$ and $\beta$ is shown to fundamentally control both the quantum and Chandrasekhar gravitational collapse mechanisms and the previously discovered mass-limit on white dwarfs. Current findings can help to understand the origin of magnetism and its inevitable role on the stability of the relativistically degenerate super-dense magnetized matter encountered in many white-dwarfs and neutron stars