Tbilisi, Georgia
Tbilisi, Georgia

The Georgian National Academy of science is a main learned society of the Georgia. It was named Georgian SSR Academy of science until November 1990. The Academy coordinates scientific research in Georgia and develops relationship with the academies and scientific centers of foreign countries. Wikipedia.


Time filter

Source Type

Inagaki T.,Hiroshima University | Kimura D.,Hiroshima University | Kohyama H.,Chung Yuan Christian University | Kvinikhidze A.,Georgian Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

Regularization dependence of the Nambu-Jona-Lasinio model leaves room for improvement. To help in choosing a suitable regularization scheme, we investigate the phase diagram on the temperature-chemical potential plane in the Nambu-Jona-Lasinio model with the dimensional regularization. While the structure of the resulting diagram shows resemblance to the one in the frequently used cutoff regularization, some results of our study indicate a striking difference between these regularizations. Diagrams in the dimensional regularization always indicate the first-order phase transition at high chemical potential, while the first-order transition does not occur in the cutoff method for some parameter sets. © 2012 American Physical Society.


Inagaki T.,Hiroshima University | Kimura D.,Hiroshima University | Kohyama H.,Chung Yuan Christian University | Kvinikhidze A.,Georgian Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The nonet meson properties are studied in the Nambu-Jona-Lasinio model at finite temperature and chemical potential using dimensional regularization. This study leads to the reasonable description which is mainly similar to one obtained in the model with the cutoff regularization. However, remarkable differences between the two regularizations are observed in the behavior of the chiral phase transition at finite chemical potential. © 2012 American Physical Society.


Vorotyntsev L.K.,Georgian Academy of Sciences
Contemporary Engineering Sciences | Year: 2016

Rotors instability is one of the most serious problems of modern engineering. There are many approaches for solution of the problem which is especially important for high-speed machinery. A known model of piece-wise linear system of oscillator supported by bearings having clearances is chosen for analytical consideration of a rotor motion and its stability. Since the procedure of prediction of the dynamical stability of investigated motions near harmonic oscillations is based on analysis of the first derivative of restoring force it is convenient to represent the derivative as expansion of Fourier series. Two cases of symmetry and asymmetry of acting external force are studied and compared. Approximate equations for computing and plotting maps of instability zones are found. The existence of a difference in principle between both considered cases is resulted from different types of expansions of Fourier series. Hence, it follows that if in a symmetric case the main (first) instability zone of the motion, supposed close to harmonic, coincides with the region of the primary resonance, asymmetry of restoring force shifts the first instability zone to the right direction. © 2016 Lev K. Vorotyntsev.


Gil A.,Siedlce University Of Natural Sciences And Humanities | Alania M.V.,Siedlce University Of Natural Sciences And Humanities | Alania M.V.,Georgian Academy of Sciences
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2011

We study temporal changes of the rigidity (R) spectrum of the harmonics of the 27-day variation of the galactic cosmic ray (GCR) intensity using neutron monitors (NM) data for the period 1965-2002. We show that the rigidity spectrum of the third harmonic (9 days) of the 27-day variation of the GCR intensity changes in a similar way as the spectra of the first and second harmonics, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. The average size of the vicinity of the corotating interaction regions, causing the 27-day variation of the GCR intensity, is less in the minimum epochs than in the maximum epochs of solar activity. A vicinity of the corotating interaction regions of larger size involves in modulation higher rigidity particles of GCR than the vicinity of smaller size; thus, this statement can be considered as one of the reasons leading to the hardening of the rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity in maximum epochs compared with minimum epochs of solar activity.We also show that the temporal changes of the power rigidity spectrum of the third harmonic of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity.We found a recurrence in the temporal changes of the amplitudes of the first harmonic of the 27-day variation of the GCR intensity and in some parameters of solar activity and solar wind. © 2010 Elsevier Ltd.


Blankleider B.,Flinders University | Kvinikhidze A.N.,Georgian Academy of Sciences | Silagadze Z.K.,Novosibirsk State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We construct the gauge invariant three-photon decay amplitude of particle-antiparticle bound states modeled by the Dyson-Schwinger and Bethe-Salpeter equations. Application to the quark-antiquark (qq¯) bound states is emphasized. An essential aspect of our formulation is that it applies to any underlying quantum field theoretic model of the qq¯ system, and not just to models, like exact QCD, where the quark self-energy Σ couples to the electromagnetic field solely via dressed quark propagators. In this way, applications to effective field theories and other QCD motivated models are envisioned. The three-photon decay amplitude is constructed by attaching currents to all possible places in the Feynman diagrams contributing to the dressed quark propagator. The gauge invariance of our construction is thus a direct consequence of respecting the underlying structure of the quantum field theory determining the dynamics. In the resultant expression for the three-photon decay amplitude, all the basic ingredients consisting of the bound-state wave function, the final-state interaction qq¯ t matrix, the dressed quark propagator, and dressed quark currents, are determined by a universal Bethe-Salpeter kernel. © 2015 American Physical Society.


Sanadze G.A.,Georgian Academy of Sciences
Russian Journal of Plant Physiology | Year: 2010

Various aspects in photobiosynthesis of isoprene and its release from leaves into the environment are presently well known. The release of isoprene from the cell can be regarded as dissipation of excess energy (entropy). The systemic release of metabolites into the external medium should be considered as a result of cell excretory activity, one of the most important functions of living systems. Energy dissipation terminates the sustained passage of thermodynamic flows and regulates the overall stability of cell stationary condition. These issues are considered in this review from the standpoint of contemporary thermodynamics. It is concluded that the excretory capacity of living cell is based on thermodynamic dissipation of entropy during irreversible processes that provide for stability and sustainable development of the living organism. © Pleiades Publishing, Ltd., 2010.


Gabrichidze G.K.,Georgian Academy of Sciences
Vulnerability, Uncertainty, and Risk: Quantification, Mitigation, and Management - Proceedings of the 2nd International Conference on Vulnerability and Risk Analysis and Management, ICVRAM 2014 and the 6th International Symposium on Uncertainty Modeling and Analysis, ISUMA 2014 | Year: 2014

The aim of this paper is to illustrate that the existing ideology of aseismic design cannot provide the reliable prognosis of the levels of damages to buildings in future. If the mankind does not realize the necessity to reduce the level of risk contained in the current ideology of aseismic design, the number of seismically instable buildings will increase even more in the XXI century. The only way of reducing the risk associated with the ideology of aseismic design appears to be the requirement for the undamaged structural behavior of building. The requirement for the undamaged structural behavior of building is something like a threshold (a level), the raising of which increases the reliability of constructions planned to be built in seismically active regions and, on the contrary, its lowering increases the uncertainties and makes the behavior unpredictable. The modern global tendencies of aseismic design are to lower this level as much as possible and to make the constructions cheaper. According to the opinion of the present writer though the level, on the contrary, should be raised, in order to keep off the chaos. © 2014 American Society of Civil Engineers.


Alania M.V.,Siedlce University Of Natural Sciences And Humanities | Alania M.V.,Georgian Academy of Sciences | Modzelewska R.,Siedlce University Of Natural Sciences And Humanities | Wawrzynczak A.,Siedlce University Of Natural Sciences And Humanities
Solar Physics | Year: 2011

We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the solar wind velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of 23 November 2007 - 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent solar wind velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwell's equations with a heliolongitudinally dependent 27-day variation of the solar wind velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter ζ (with a correlation coefficient of -0.91±0.05), which is proportional to the product of the solar wind velocity V and the strength of the interplanetary magnetic field B (ζ~VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect. © 2011 Springer Science+Business Media B.V.


Wawrzynczak A.,Siedlce University Of Natural Sciences And Humanities | Alania M.V.,Siedlce University Of Natural Sciences And Humanities | Alania M.V.,Georgian Academy of Sciences
Advances in Space Research | Year: 2010

We study the Forbush decrease of the galactic cosmic ray intensity observed in 9-25 September 2005 using the experimental data and a newly developed time-dependent three dimensional modeling. We analyze neutron monitors and muon telescopes, and the interplanetary magnetic field data. We demonstrate a clear relationship between the rigidity (R) spectrum exponent (γ) of the Forbush decrease and the exponent (ν) of the power spectral density of the components of the interplanetary magnetic field in the frequency range of ∼ 10-6-10-5 Hz. We confirm that an inclusion of the time-dependent changes of the exponent ν makes the newly developed nonstationary three dimensional model of the Forbush decrease compatible with the experimental data. Also, we show that the changes of the rigidity spectrum exponent γ does not depend on the level of convection of the galactic cosmic rays stream by solar wind; depending on the changes of the exponent ν, i.e. on the state of the turbulence of the interplanetary magnetic field. © 2009 COSPAR.


News Article | March 10, 2016
Site: news.yahoo.com

David Lordkipanidze of the Georgian Academy of Sciences shows a 1.75-million-year-old skull and jawbone excavated near the town of Dmanisi, some 85 kms south west of Tbilisi, Georgia, in this July 8, 2002 file photo. REUTERS/David Mdzinarishvili/Files More WASHINGTON (Reuters) - A study in which people chewed on pieces of raw goat meat and vegetables smacked with a rock is shedding light on how changes long ago in the way our ancestors dined paved the way for physiological advances that helped make us who were are today. Scientists said on Wednesday the advent of meat-eating combined with the use of simple tone tools to make food easier to consume meant that members of the human lineage about 2.5 million years ago all of a sudden had less need for chewing. Without needing to spend much of the day chewing food as chimpanzees do, our ancestors underwent significant evolutionary changes, acquiring smaller teeth, jaws and chewing muscles while losing the snout possessed by their predecessors. "Shortening the snout might have been beneficial for producing articulate speech, for having a more balanced head, especially useful when running, or perhaps for other reasons," Harvard University evolutionary anthropologist Daniel Lieberman said. The changes also may have enabled the development of larger brains in early human species like Homo erectus compared to earlier members of the human lineage like Australopithecus, who combined ape-like and human-like traits. Meat compared to plants added a calorically dense food to the diet of these early humans as their brains and bodies got bigger. The researchers conducted experiments measuring how much chewing effort was expended in eating the type of diet our ancestors are thought to have had. Cooking was not commonplace until roughly 500,000 years ago. Study volunteers chewed on tough raw goat meat, selected to mimic wild game, and three root vegetables: beets, carrots and yams. Electrodes were placed on their faces to measure chewing activity. Harvard evolutionary anthropologist Katherine Zink, the study's lead author, said the amount of chewing declined markedly when the food was processed with the type of basic stone tools used at the time: slicing the meat into smaller pieces and pounding the vegetables six times. The number of chews dropped by 17 percent and the chewing force by 20 percent while the volunteers were able to swallow meat bits that were about 41 percent smaller and thus more digestible. Lieberman served as a test subject before the volunteers stepped in. "I can tell you that eating raw goat is not pleasant. It's a little on the gross side," Lieberman said. "It's really amazingly like chewing gum." Lieberman said unlike carnivores, whose teeth are tailor-made for slicing meat, human teeth are "really designed like mortars and pestles, for crushing." The research was published in the journal Nature.

Loading Georgian Academy of Sciences collaborators
Loading Georgian Academy of Sciences collaborators