Quantum gravitational corrections to the stress-energy tensor around the rotating BTZ black hole

Modes emerging out of a collapsing black hole are red-shifted to such an extent that Hawking radiation at future null infinity consists of modes that have energies beyond the Planck scale at past null infinity. This indicates that physics at the Planck scale may modify the spectrum of Hawking radiation and the associated stress-energy tensor of the quantum field. Recently, it has been shown that, the T-duality symmetry of string fluctuations along compact extra dimensions leads to a modification of the standard propagator of point particles in quantum field theory. At low energies (when compared to the string scale), the modified propagator is found to behave as though the spacetime possesses a minimal length, say, \lp, which we shall assume to be of the order of the Planck length. We utilize the duality approach to evaluate the modified propagator around the rotating Banados-Teitelboim-Zanelli black hole and show that the propagator is finite in the coincident limit. We compute the stress-energy tensor associated with the modified Green's function and illustrate graphically that the quantum gravitational corrections turn out to be negligibly small. We conclude by briefly commenting on the results we have obtained.Comment: v1. 7 pages, 2 figures; v2. 11 pages, 4 figures, discussion extended to the case of the rotating BTZ black hole, figures improve

The thermodynamic structure of Einstein tensor

We analyze the generic structure of Einstein tensor projected onto a 2-D spacelike surface S defined by unit timelike and spacelike vectors u_i and n_i respectively, which describe an accelerated observer (see text). Assuming that flow along u_i defines an approximate Killing vector X_i, we then show that near the corresponding Rindler horizon, the flux j_a=G_ab X^b along the ingoing null geodesics k_i normalised to have unit Killing energy, given by j . k, has a natural thermodynamic interpretation. Moreover, change in cross-sectional area of the k_i congruence yields the required change in area of S under virtual displacements \emph{normal} to it. The main aim of this note is to clearly demonstrate how, and why, the content of Einstein equations under such horizon deformations, originally pointed out by Padmanabhan, is essentially different from the result of Jacobson, who employed the so called Clausius relation in an attempt to derive Einstein equations from such a Clausius relation. More specifically, we show how a \emph{very specific geometric term} [reminiscent of Hawking's quasi-local expression for energy of spheres] corresponding to change in \emph{gravitational energy} arises inevitably in the first law: dE_G/d{\lambda} \alpha \int_{H} dA R_(2) (see text) -- the contribution of this purely geometric term would be missed in attempts to obtain area (and hence entropy) change by integrating the Raychaudhuri equation.Comment: added comments and references; matches final version accepted in Phys. Rev.

Synthesis and Characterization of Biomass and Clay Mineral Based Adsorbents for the Removal of Cationic Dye and Metal Ion from Wastewater by Adsorption

Biomass pine cone (Pinus. Radiate) and eucalyptus bark (Sheathiana) based biochar were synthesized through a slow pyrolysis method. Biomass based biochar and kaolin adsorbents were characterized and their adsorptive effectiveness in the removal of methylene blue dye and nickel metal ions were studied. Also, the mechanism of adsorption and identification of various process parameters and their optimum values have been explored here under batch and continuous column adsorption study

Line Current Harmonic Reduction in AC-DC PWM Converter Using Genetic Algorithm

In this paper, AC/DC converters are widely used to get regulated power supply for battery charging and DC motor speed control. SCR converters are preferred in the field of High voltage DC energy transmission, superconductor magnetic energy storage, etc. However these converters have low power factor and also result in higher order harmonics.This paper proposes the application of Genetic algorithms (GAs) to find the switching angles for line current harmonic reduction in AC/DC type converter. Harmonic reduction is redrafted as an optimization problem and GA is applied.The harmonic elimination methods used in AC/DC converters are similar to those employed in PWM inverters or in AC choppers. The solution is obtained using genetic algorithm tool in MATLAB. The dual objectives of harmonic elimination and output voltage regulation are reframed as an optimization task and the switching instances are identified through the steps of GA

Fast lightweight block cipher design with involution substitution permutation network (SPN) structure

In the present paper, a new cryptographic lightweight algorithm has been developed for the internet of things (IoT) applications. The submitted cipher designed with the involution Substitution Permutation Network SPN structure. The involution structure means that the same encryption algorithm is used in the decryption process except the ciphering key algorithm is applied in reverse order. The introduced algorithm encrypts the data with a block size of 128-bit 192-bit or 256-bit, which iterative with 10, 12 and 14-rounds respectively similar to the AES cipher. The design aspect supports an elegant structure with a secure involution round transformation. The main round is built without S-Box stage instead that it uses the on-fly immediate computing stage and the involution of mathematical invertible affine equations. The proposed cipher is adopted to work in a restricted environment and with limited resources pertaining to embedded devices. The proposed cipher introduces an accepted security level and reasonable gate equivalent (GE) estimation with fast implementation

Evaluating Performance Competencies in the Royal Saudi Air Force Engineering Directorate and Squadrons

The effectiveness of tasks performed by the directorate of aeronautical engineering and squadrons in RSAF directly impacts flight safety, which in turn influences the organization either positively or negatively. Therefore, improving engineers\u27 competencies will improve the overall performance of the organization. The study refined and reconstructed a model, namely a T-shape competency model, to assess the engineers\u27 competencies which revealed some management and competency-related deficiencies and concluded with managerial recommendations

A longitudinal study of the concerns of students becoming science teachers in the Yemen Arab Republic

The process of becoming a teacher is an area of a great deal of research. Different researchers have focused on different parts of the process. This study examines the concerns and their development for a group of Yemeni student-teachers as they become science teachers. After discussing the context of teacher training in the Yemen Arab Republic, the different arguments put forward by researchers who investigated the process of becoming a teacher, were examined. The field work was conducted in the Yemen between March 1983 and January 1985. Two different interview schedules with open-ended questions were used: one was general and the focus of the another was teaching-a-lesson. The former was conducted at three different occasions: during the second term of the third year i.e. before teaching practice, during the second term of the fourth year i.e. after teaching practice, and during the first few months of the first year of teaching. The latter was conducted during teaching practice and during the first few months of the first year of teaching. Both interviews were conducted for thirty-one Yemeni student-teachers at Sana'a University as they become science teachers. A further interview was conducted for the Faculty of Education staff to know their reactions to their students' views of their training. The concerns' development of the group and some individuals was followed, and the relationship of the findings of this research to the different theoretical arguments was considered. The research shows the stability and change of student teachers' concerns as they become science teachers in the Yemen. In examining this phenomenon the research points out the importance of: the kind of concern investigated, when they are investigated, and the situational and the personal factors which all have bearing on the process of concerns' development during the process of becoming a teacher

Description of a new moss frog from the south-western Cape (Anura: Ranidae: Arthroleptella)

A new species of moss frog, genus Arthroleptella, is described from the Kleinrivier mountains of the south-western Cape. It is morphologically indistinguishable from the other three species in the area. The four Cape species are allopatric, each has a unique male advertisement call, and preliminary molecular data shows consistent differences

Study of Nonlinear Refraction and Nonlinear Absorption Coefficients of Different CdS Film Thickness by diode laser

In the present work, different thicknesses of CdS film were prepared by chemical bath deposition. Z-Scan technique was used to study the nonlinear refractive index and nonlinear absorption coefficients. Linear optical testing were done such as transmission test, and thickness of films were done by the interference fringes (Michelson interferometer). Z-scan experiment was performed at 650nm using CW diode laser and at 532nm wavelength. The results show the effect of self-focusing and defocusing that corresponds with nonlinear refraction n2. The effect of two-photon absorption was also studied, which correspond to the nonlinear absorption coefficient B