Asvarov A.I.,Azerbaijan Academy of Sciences
Astronomy and Astrophysics | Year: 2014
The size distribution of supernova remnants (SNRs) can help to clarify the various aspects of their evolution and interaction with the interstellar medium (ISM). Since the observed samples of SNRs are a collection of objects with very different ages and origin that evolve in different conditions of the ISM, statistical Monte Carlo methods can be used to model their statistical distributions. Based on very general assumptions on the evolution, we have modeled samples of SNRs at various initial and environmental conditions, which were then compared with observed collections of SNRs. In the evolution of SNRs the pressure of the ISM is taken into account, which determines their maximum sizes and lifetimes. When comparing the modeled and observed distributions, it is very important to have homogeneous observational data free from selection effects. We found that a recently published collection of SNRs in M33 satisfies this requirement if we select the X-ray SNRs with hardness ratios in a limited range of values. An excellent agreement between distributions of this subset of SNRs and the subset of modeled SNRs was reached for a volume filling-factor of the warm phase of the ISM (partly ionized gas with nH ~ 0.2-0.5 cm-3; T ~ 8000-10 000 K) in M33 of ~90%. The statistical distributions constructed in this way, which reproduce practically all the statistical properties of observed SNRs, allowed us to obtain one of the important parameters of M33: the birthrate is one SNR every 140-150 yr, and the total number of SNRs with a shock Mach number Ms = 2 is larger than ~1000. © 2014 ESO.
Aliyev J.A.,Research Institute of Crop Husbandry |
Aliyev J.A.,Azerbaijan Academy of Sciences
Physiologia Plantarum | Year: 2012
The results of the numerous measurements obtained during the last 40 years on gas exchange rate, photosynthetic carbon metabolism by exposition in 14CO 2 and activities of primary carbon fixation enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC/O), in various wheat and soybean genotypes grown over a wide area in the field and contrasting in photosynthetic traits and productivity are presented in this article. It was established that high productive wheat genotypes (7-9 t ha -1) with the optimal architectonics possess higher rate of CO 2 assimilation during the leaf ontogenesis. Along with the high rate of photosynthesis, high values of photorespiration are characteristic for the high productive genotypes. Genotypes with moderate (4-5 t ha -1) and low (3 t ha -1) grain yield are characterized by relatively low rates of both CO 2 assimilation and photorespiration. A value of photorespiration constitutes 28-35% of photosynthetic rate in contrasting genotypes. The activities of RuBPC and RuBPO were changing in a similar way in the course of the flag leaf and ear elements development. High productive genotypes are also characterized by a higher rate of biosynthesis and total value of glycine-serine and a higher photosynthetic rate. Therefore, contrary to conception arisen during many years on the wastefulness of photorespiration, taking into account the versatile investigations on different aspects of photorespiration, it was proved that photorespiration is one of the evolutionarily developed vital metabolic processes in plants and the attempts to reduce this process with the purpose of increasing the crop productivity are inconsistent. © 2012 Physiologia Plantarum.
Huseynova I.M.,Azerbaijan Academy of Sciences
Biochimica et Biophysica Acta - Bioenergetics | Year: 2012
Two durum (Triticum durum L.), Barakatli-95 and Garagylchyg-2; and two bread (Triticum aestivum L.) wheat cultivars, Azamatli-95 and Giymatli-2/17 with different sensitivities to drought were grown in the field on a wide area under normal irrigation and severe water deficit. Drought caused a more pronounced inhibition in photosynthetic parameters in the more sensitive cvs Garagylchyg-2 and Giymatli-2/17 compared with the tolerant cvs Barakatli-95 and Azamatli-95. Upon dehydration, a decline in total chlorophyll and relative water content was evident in all cultivars, especially in later periods of ontogenesis. Potential quantum yield of PS II (Fv/Fm ratio) in cv Azamatli-95 was maximal during stalk emergency stage at the beginning of drought. This parameter increased in cv Garagylchyg-2, while in tolerant cultivar Barakatli-95 significant changes were not observed. Contrary to other wheat genotypes in Giymatli-2/17 drought caused a decrease in PS II quantum yield. Drought-tolerant cultivars showed a significant increase in CAT activity as compared to control plants. In durum wheat cultivars maximal activity of CAT was observed at the milk ripeness and in bread wheat cultivars at the end of flowering. APX activity also increased in drought-treated leaves: in tolerant wheat genotypes maximal activity occurred at the end of flowering, in sensitive ones at the end of ear formation. GR activity increased in the tolerant cultivars under drought stress at all stages of ontogenesis. SOD activity significantly decreased in sensitive cultivars and remained at the control level or increased in resistant ones. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. © 2011 Elsevier B.V. All rights reserved.
Kelbaliyev G.I.,Azerbaijan Academy of Sciences
Theoretical Foundations of Chemical Engineering | Year: 2011
This article, which is largely a review, deals with the drag force and drag coefficient for rigid spherical and deformable particles in ordinary and non-Newtonian fluids. The most important theoretical formulas for small Reynolds numbers of Re ≪ 1 and semiempirical formulas for the drag coefficient in a wide Re range up to 106 are presented. The deformation of drops and bubbles and its effect on the drag coefficient are considered. © Pleiades Publishing, Ltd., 2011.
Aliguliyev R.M.,Azerbaijan Academy of Sciences
Computational Intelligence | Year: 2010
Multi-document summarization is a process of automatic creation of a compressed version of a given collection of documents that provides useful information to users. In this article we propose a generic multi-document summarization method based on sentence clustering. We introduce five clustering methods, which optimize various aspects of intra-cluster similarity, inter-cluster dissimilarity and their combinations. To solve the clustering problem a modification of discrete particle swarm optimization algorithm has been proposed. The experimental results on open benchmark data sets from DUC2005 and DUC2007 show that our method significantly outperforms the baseline methods for multi-document summarization. © 2010 Wiley Periodicals, Inc.