Curvature Inheritance Symmetry In Riemannian Spaces with Applications to String Cloud and String Fluids

We study, in this paper, curvature inheritance symmetry (CI), $\pounds_{\xi}R_{bcd}^{a}=2\alpha R_{bcd}^{a}$, where $\alpha$ is a scalar function, for string cloud and string fluid in the context of general relativity. Also, we have obtained some result when a proper CI (i.e., $\alpha \neq 0$) is also a conformal Killing vector.Comment: 14 pages, Latex, no figures, to appear in the International Journal of Modern Physics D (IJMPD), Vol.8, No.5(Oct.,1999

First-principles investigation of superconductivity in the body-centred tetragonal LaRu2P2

© 2016 Informa UK Limited, trading as Taylor & Francis Group.We have investigated the ground state and electronic properties of LaRu2P2 in the ThCr2Si2 structure using a generalised gradient approximation of the density functional theory and the ab initio pseudopotential method. We find that the calculated electronic properties of LaRu2P2 exhibit three-dimensional rather than two-dimensional characteristics in spite of the apparent two dimensionality in its atomic structure. An interesting feature of the phonon dispersion curves is the phonon anomaly in the lowest transverse acoustic branch as well as the longitudinal acoustic branch. We have shown that these phonon anomalies give rise to large electron-phonon interaction, as is evident from the calculated Eliashberg spectral function α2) F(ω) By integrating this spectral function, the value of average electron-phonon coupling parameter is calculated to be 0.85, from which the superconducting critical temperature is estimated to be 3.74 K, in gratifying accord with its experimental value of 4.0 K.This work was supported by the Scientific and Technical Research Council of Turkey (TÜB˙ITAK) [project number MFAG-114F192]

Spotlight mode SAR image reconstruction by compressed sensing [Sikiştirilmiş algilama kullanilarak nokta ki̇pli̇ SAR goruntu oluşturulmasi]

In this work, LASSO formulation, which is one of the comppessed sensing techniques, is used as a method of SAR image reconstruction. Simulations on the real SAR images are performed in order to analyze the effect of the τ parameter in LASSO formulation to the formed SAR imagery. Formed images are compared. A parameter, derived from signal to noise ratio and cross correlation, is suggested to robustly select the sparsity limit parameter τ. © 2011 IEEE

SAR image reconstruction by EMMP algorithm [EMMP algori̇tmasi kullanilarak SAR görüntü oluşturulmasi]

In this work, EMMP algorithm is used to solve the SAR image reconstruction problem which is modelled in the compressed sensing context. It is found that the sparsity parameter of the target region is an important parameter determining the quality of the output image. The proposed method is applied to the real SAR data and provided high quality outputs. © 2012 IEEE

Adaptive decision fusion based cooperative spectrum sensing for cognitive radio systems [Akilli radyo sistemleri i̇çin uyarlanir veri birleştirme tabanli i̇şbirlikli spektrum algilama yöntemi]

In this paper, an online Adaptive Decision Fusion (ADF) framework is proposed for the central spectrum awareness engine of a spectrum sensor network in Cognitive Radio (CR) systems. Online learning approaches are powerful tools for problems where drifts in concepts take place. Cooperative spectrum sensing in cognitive radio networks is such a problem where channel characteristics and utilization patterns change frequently. The importance of this problem stems from the requirement that secondary users must adjust their frequency utilization strategies in such a way that the communication performance of the primary users would not be degraded by any means. In the proposed framework, sensing values from several sensor nodes are fused together by weighted linear combination at the central spectrum awareness engine. The weights are updated on-line according to an active fusion method based on performing orthogonal projections onto convex sets describing power reading values from each sensor. The proposed adaptive fusion strategy for cooperative spectrum sensing can operate independent from the channel type between the primary user and secondary users. Results of simulations and experiments for the proposed method conducted in laboratory are also presented. © 2011 IEEE

The role of Tc-99m (V) DMSA scintigraphy in the evaluation of superscan on bone scintigraphy

Purpose: This study evaluated the biodistribution of Tc-99m (V) DMSA in patients with superscans on bone imaging and defined its role in differentiating the underlying cause. Methods: Nine patients (five with metastatic and four with metabolic bone disease) with classical superscans were entered into the study. All patients had the necessary radiologic and biochemical studies and a final diagnosis was reached accordingly. Tc-99m (V) DMSA scintigraphy was performed 1 week after Tc-99m MDP whole-body bone imaging. Results: In four of five patients with widespread skeletal metastases, Tc-99m (V) DMSA scan showed diffusely increased bone uptake. In the remaining patient, the Tc-99m (V) DMSA scan showed a normal distribution pattern. All patients with metabolic bone disease had increased bone uptake on Tc-99m (V) DMSA scans. Conclusion: Tc-99m (V) DMSA shows increased bone uptake in patients having a superscan appearance in metastatic or metabolic bone disease. Tc-99m (V) DMSA imaging may play a role in the evaluation of patients with equivocal bone scan findings for a superscan