Time filter

Source Type

Agadjanov D.,University of Bonn | Agadjanov D.,Georgian University of St. Andrew | Meissner U.-G.,University of Bonn | Meissner U.-G.,Jülich Research Center | Rusetsky A.,University of Bonn
Journal of High Energy Physics | Year: 2014

The possibility of imposing partially twisted boundary conditions is investigated for the scalar sector of lattice QCD. According to the commonly shared belief, the presence of quark-antiquark annihilation diagrams in the intermediate state generally hinders the use of the partial twisting. Using effective field theory techniques in a finite volume, and studying the scalar sector of QCD with total isospin I = 1, we however demonstrate that partial twisting can still be performed, despite the fact that annihilation diagrams are present. The reason for this are delicate cancellations, which emerge due to the graded symmetry in partially quenched QCD with valence, sea and ghost quarks. The modified Lüscher equation in case of partial twisting is given. © 2014 The Author(s).


PubMed | Phenomenex Inc., Tbilisi State University and Georgian University of St. Andrew
Type: Journal Article | Journal: Journal of separation science | Year: 2016

The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination.


Kachakhidze M.K.,Georgian University of St. Andrew | Kereselidze Z.A.,Nodia Institute of Geophysics | Kachakhidze N.K.,Georgian University of St. Andrew | Ramishvili G.T.,Ilia State University | Kukhianidze V.J.,Ilia State University
Natural Hazards and Earth System Science | Year: 2012

The present paper deals with an attempt to check the theoretical model of self-generated seismo-electromagnetic oscillations of LAI system on the basis of retrospective data. Application of the offered simple model enables one to explain qualitatively the mechanism of VLF electromagnetic emission initiated in the process of an earthquake preparation. Besides, the model enables us to associate telluric character geoelectric and geomagnetic perturbations incited by rock polarization and self-generated electromagnetic oscillations of lithosphere-atmosphere system. L'Aquila earthquake taken as an example to isolate reliably the Earth VLF emission from the magnetospheric electromagnetic emission of the same frequency range, MHD criterion is offered together with geomagnetic activity indexes. On the basis of the considered three earthquakes, according to the opinion of authors the model of self-generated seismo-electromagnetic oscillations of the LAI system will enable us to approach the problem of resolution of earthquake prediction with certain accuracy. © Author(s) 2012. CC Attribution 3.0 License.


Lomidze I.,Georgian University of St. Andrew | Lomidze T.,Tbilisi State University
10th International Multidisciplinary Scientific Geoconference and EXPO - Modern Management of Mine Producing, Geology and Environmental Protection, SGEM 2010 | Year: 2010

Starting from the recently proposed hypothesis [1] on the Moon formation from the ejection of terrestrial mantle material in a heat-propelled jet, triggered by a run-away natural georeactor at Earth's core-mantle boundary, we estimate the energy losses in the Earth-Moon system, develop dynamics of this process and compare produced value of the heat with known estimations for heat produced by heavy radionuclides fusion in the Earth body. We conclude that the values of heat produced in these two processes are comparable in long-time scale, rather than in short-time scale. Therefore these differences should be taken into account when considering the early evolution of the Earth. We propose a possible direct test of the hypothesis proposed in [1].


Gordeziani D.,Tbilisi State University | Davitashvili T.,Tbilisi State University | Meladze H.,Georgian University of St. Andrew
CSIT 2015 - 10th International Conference on Computer Science and Information Technologies | Year: 2015

The present work is devoted to the statement and analysis of one nonlocal contact problem for Poisson's equation in two-dimensional domain. For numerical solution the iteration process is constructed, which allows one to reduce the solution of the initial problem to the solution of a sequence of classical Dirichlet problems. The algorithm is suitable for parallel realization. The specific problem is considered as example and solved numerically by using Wolfram Mathematica. © 2015 IEEE.


Agadjanov D.,University of Bonn | Agadjanov D.,Georgian University of St. Andrew | Guo F.-K.,University of Bonn | Rios G.,University of Bonn | Rusetsky A.,University of Bonn
Journal of High Energy Physics | Year: 2015

Abstract: We propose a method to study the nature of exotic hadrons by determining the wave function renormalization constant Z from lattice simulations. It is shown that, instead of studying the volume-dependence of the spectrum, one may investigate the dependence of the spectrum on the twisting angle, imposing twisted boundary conditions on the fermion fields on the lattice. In certain cases, e.g., the case of the DK bound state which is addressed in detail, it is demonstrated that the partial twisting is equivalent to the full twisting up to exponentially small corrections. © 2015, The Author(s).


Kachakhidze M.K.,Georgian University of St. Andrew | Kachakhidze N.K.,Georgian University of St. Andrew | Kaladze T.D.,Tbilisi State University
Physics and Chemistry of the Earth | Year: 2015

Recent satellite and ground-based observations prove that during the formative period of earthquakes VLF/LF and ULF electromagnetic emissions are observed in seismogenic areas. This work offers an original model of self-generated electromagnetic oscillations of local segments of the lithospheric origins of the emissions. In the paper, the seismogenic area is considered to be an oscillatory-distributed system. This model simplifies physical analyses of the nonlinear effects and qualitatively explains the mechanisms that generate very low frequency electromagnetic waves in the period prior to an earthquake. © 2015 Elsevier Ltd.


PubMed | Georgian University of St. Andrew
Type: | Journal: Georgian medical news | Year: 2016

In the present study, the possible beneficial effect of memantine on the Okadaic Acid (OA) induced spatial short-term memory impairment was examined in spatial alternation task, and the neuroprotective potential of memantine on OA-induced structural changes in the hippocampus was evaluated by Nissl staining. OA was dissolved in artificial cerebrospinal fluid (aCSF) and injected intracerebroventriculary (ICV) 200 ng in a volume of 10 l bilaterally. Vehicle control received aCSF ICV bilaterally. Control and OA injected rats were divided into 2 subgroups injected i.p. with saline or memantine (5 mg/kg). Memantine or saline were given daily for 13 days starting from the day of OA injection. Behavioral study showed that bilateral ICV microinjection of OA induced impairment in spatial short-term memory. Nissl staining in the present study showed that the ICV microinjection of OA significantly decreased the number of surviving pyramidal neurons in the CA1 region of the hippocampus. Chronic administration of memantine effectively attenuated OA induced spatial short-term memory impairment and the OA-induced neuropathological changes in the hippocampus. Therefore, ICV injection of OA can be used as an experimental model to study mechanisms of neurodegeneration and define novel therapeutics targets for AD pathology.


PubMed | Georgian University of St. Andrew
Type: | Journal: Georgian medical news | Year: 2016

The present study investigated spatial working memory assessed in spontaneous alternation (SA) task and hippocampal glutamate and GABA release prior to, during, and after SA test in sham-operated and electrolytic medial septal (MS) lesioned rats. Also, have been investigated the effects of MS lesion on KCl-stimulated release of glutamate and GABA in the hippocampus. Behavioral study showed that electrolytic lesion of MS significantly impaired SA performance. Although both groups of animals had an insignificant rise in their respective hippocampal glutamate efflux during the SA, the rise of MS lesioned animals was blunted when compared with control animals. Hippocampal GABA levels did not change during behavioral testing in both groups. Most of control animals showed increase in KCl-stimulated glutamate release. By contrast, only one MS lesioned rat showed increase in glutamate release in response to KCl stimulation. Most of control and MS lesioned rats were non-responders in GABA release in response to KCl stimulation. Decreased glutamate release (upon stimulation) in the MS lesioned rats may contribute to spatial working memory impairment in these animals. We propose that SA testing coupled with in vivo microdialysis sampling represents a suitable approach to revealing the neurochemical correlates of hippocampal-dependent memory function, and thus could be a useful tool for better understanding of the neurochemical basis of cognitive decline associated with various disorders and neurodegenerative diseases.


PubMed | Georgian University of St. Andrew
Type: | Journal: Georgian medical news | Year: 2016

In the present study, we evaluated and compared effect of intracerebroventricular (ICV) and intrahippocampal bilateral microinjection of okadaic acid (OA) on spatial memory function assessed in one day water maze paradigm and hippocampal structure in rats. Rats were divided in following groups: Control(icv) - rats injected with ICV and aCSF; Control(hipp) - rats injected intrahippocampally with aCSF; OAicv - rats injected with ICV and OA; OAhipp - rats injected intrahippocampally with OA. Nissl staining of hippocampal sections showed that the pyramidal cell loss in OAhipp group is significantly higher than that in the OAicv. The results of behavioral experiments showed that ICV or intrahippocampal bilateral microinjection of OA did not affect learning process and short-term spatial memory but induced impairment in spatial long-term memory assessed in probe test performance 24 h after training. OA-induced spatial memory impairment may be attributed to the hippocampal cell death. Based on these results OA induced memory deficit and hippocampal cell loss in rat may be considered as a potential animal model for preclinical evaluation of antidementic drug activity.

Loading Georgian University of St. Andrew collaborators
Loading Georgian University of St. Andrew collaborators