Entity

Time filter

Source Type

Krsehir, Turkey

The present study aimed to understand how Anatolian ground squirrels, Spermophilus xanthoprymnus (Bennett, 1835), have responded to global climate changes through the Late Quaternary glacial-interglacial cycles. Accordingly, ecological niche modelling was used, together with molecular phylogeography. Using species occurrence data compiled from field observations and relevant sources and the maximum entropy machine learning algorithm in MAXENT, an ecological niche model was developed to predict the potential geographical distribution of S. xanthoprymnus under reconstructed past (the Last Interglacial, approximately 130000-116000years ago and the Last Glacial Maximum, 21000years ago) and present (1950-2000) bioclimatic conditions. In addition, using cytochrome b mitochondrial DNA sequences deposited in GenBank and the Bayesian skyline plot in BEAST, demographic events (population fluctuations) were further assessed over the history of Anatolian ground squirrels. Combined ecological niche modelling and molecular phylogeography revealed that S. xanthoprymnus, itself also a temperate (mid-latitude) species, has responded to global climate changes through the Late Quaternary glacial-interglacial cycles in a fashion converse to that of most temperate (mid-latitude) species: its range expanded rather than contracted during the glacial periods and contracted rather than expanded during the interglacial periods. In other words, Anatolian ground squirrels have been in refugia during the interglacial periods, suggesting that the classical paradigm of glacial range contraction and interglacial range expansion for temperate species may not be as general as previously assumed. © 2013 The Linnean Society of London. Source


Erdogdu Y.,Ahi Evran University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra and electronic properties of Esculetin (ESC). The FT-IR, FT-Raman and FT-NMR spectra have been recorded and analyzed. The molecular geometry, harmonic vibrational frequencies, chemical shifts, HOMO, LUMO energies and molecular electrostatic potential map of ESC have been calculated by using Density Functional Theory (B3LYP) with 6-311G++(d,p), cc-pVDZ, cc-pVQZ and cc-pVTZ basis sets. © 2013 Elsevier B.V. All rights reserved. Source


A new solid-phase extraction method was developed for trace analysis of cobalt on Duolite XAD-761 resin by using flame atomic absorption spectrometry (FAAS). The optimum experimental conditions for the quantitative sorption of Co(II)-PAR (cobalt chelates with 4-(2-Pyridylazo) resorcinol), pH, effect of sample flow rate, concentration of eluent, sorption capacity of resin and the effect of diverse ions on the preconcentration of analytes have been investigated. The optimum pH values for quantitative sorption of Co (II)-PAR were between 5 and 7.5. Eluted process was performed by 4 mL ethanol. The sorption capacity of resin was determined to be 8.6 mg g-1 for cobalt with a preconcentration factor of 150. In optimized conditions, the detection limit for cobalt ions was found to be 0.36 μg L-1. The accuracy of the proposed procedure was checked by using NIST 1573 a tomato leave as a standard reference material. The achieved results were in good agreement with certified values. The proposed method was applied for the determination of cobalt in different water samples, such as city line, geothermal, river and lake. © 2010 Bentham Science Publishers Ltd. Source


A phylogenetic comparative analysis of geographic variation in body size of an obligately hibernating marmotine species (Anatolian ground squirrels, Spermophilus xanthoprymnus) is presented in relation to environmental variables that pertain to four principal hypotheses (heat conservation, heat dissipation, primary productivity, and seasonality hypotheses). Adult Anatolian ground squirrels (78 males and 90 females) were collected from ten geographic localities in Anatolia for use in morphometric analyses. First, the study tested whether significant variation in body size occurs over the geographic range of S. xanthoprymnus. Then, to understand the possible cause(s) of the observed pattern of geographic variation in body size of Anatolian ground squirrels, four hypotheses were tested, separately and simultaneously, using a phylogenetic comparative method. Overall, food availability (primary productivity hypothesis) and, especially in males, over-winter fasting endurance (seasonality hypothesis) are likely the primary underlying mechanisms generating the observed pattern of increasing body size towards colder, more seasonal environments, with higher summer precipitation and productivity (or a Bergmannian size pattern). © 2010 The Linnean Society of London. Source


Arkan N.,Ahi Evran University
Journal of Physics and Chemistry of Solids | Year: 2013

The elastic, electronic, and phonon properties of the intermetallic compounds Zr3Al and Sc3Al in the L12 structure have been investigated in detail by employing an ab initio pseudopotential method and a linear-response technique within a generalized gradient approximation (GGA) of the density-functional theory (DFT) scheme. The calculated ground-state properties such as lattice constants and bulk modulus agree well with the previous theoretical calculations. The numerical first-principles calculations of the elastic constants have been used to calculate C11, C12, and C44 for Zr 3Al and Sc3Al. The electronic band structures of Zr 3Al and Sc3Al show that at the Fermi level, a major part of the contribution comes from Zr 4d (Sc 3d) states. The phonon-dispersion curves and phonon total and partial density of states based on the linear-response method have been investigated for both materials. Temperature variations of specific heat capacity in the range of 0-500 K are obtained using the quasi-harmonic model. © 2013 Elsevier Ltd. Source

Discover hidden collaborations