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Articles 61 - 90 of 175
Full-Text Articles in Physical Sciences and Mathematics
Properties Of Ag-Doped Bi_{(1.6)}Pb_{(0.4)}Sr_2ca_3cu_{(4-X)}Ag_Xo_Y (2234) Oxides Prepared By S.S.R. Method, Süleyman Bolat, E. Yanmaz, H. Cömert
Properties Of Ag-Doped Bi_{(1.6)}Pb_{(0.4)}Sr_2ca_3cu_{(4-X)}Ag_Xo_Y (2234) Oxides Prepared By S.S.R. Method, Süleyman Bolat, E. Yanmaz, H. Cömert
Turkish Journal of Physics
The effect of Ag-doping Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$Ca$_{3}$Cu$_{4-x}$Ag$_{x}$O$_{y}$ compounds (x=0.0-1.0), prepared by conventional Solid-State-Reaction (SSR) technique, was studied using x-ray diffraction (XRD) and electrical resistivity. The high-T$_{c}$ fraction of the 2223 phase, formed from the nominal composition of 2234, decreases with increasing Ag content. From lattice parameter calculations it follows that Ag-doping the unit cell phase of (Bi,Pb)$_{2}$Sr$_{2}$Ca$_{2}$Cu$_{3}$O$_{y}$ is limited to the value of x$\leq$0.1. The zero resistance critical temperature (T$_{c,zero}$) was determined from the resistivity curves for all samples. The value of T$_{c,zero}$ decreases slightly to 106 K for x$\leq$0.4 and when the nominal silver content increases up to x=0.7 or more …
The Interaction Of The Dipole Moment Of The Water Molecule With The Interface States Of The Cuprous Oxide/Cupric Oxide Junction, Necmi̇ Seri̇n, Tülay Seri̇n, Basri̇ Ünal
The Interaction Of The Dipole Moment Of The Water Molecule With The Interface States Of The Cuprous Oxide/Cupric Oxide Junction, Necmi̇ Seri̇n, Tülay Seri̇n, Basri̇ Ünal
Turkish Journal of Physics
An Au/CuO/Cu$_{2}$O/Cu sandwich structure has been obtained by growing successive Cu$_{2}$O and CuO layers on a Cu sheet. A gold metal contact was formed CuO side at pressure of $1\times10^{-6}$ Torr. Current-voltage characteristics and capacitance of the system were seen to change over a great extent due to the presence of humidity. The effect of the humidity on Au/CuO/Cu$_{2}$O/Cu is explored through the effect of water's dipole moment.
Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov
Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov
Turkish Journal of Physics
2--Dim quantum Poincar\'e Group $E_q(1,1)$ at roots of unity, its dual $U_q(e(1,1))$ and some of its homogeneous spaces are introduced. Invariant integrals on $E_q(1,1)$ and its invariant discrete subgroup $E(1,1\mid p)$ are constructed. $*$--Representations of the quantum algebra $U_q(e(1,1))$ constructed in the homogeneous space $SO(1,1\mid p)$ are integrated to the pseudo--unitary representations of $E_q(1,1)$ by means of the universal $T$--matrix. $U_q(e(1,1))$ is realized on the quantum plane $E_q^{(1,1)}$ and the eigenfunctions of the complete set of observables are obtained in the angular momentum and momentum basis. The matrix elements of the pseudo--unitary irreducible representations are given in terms of the …
Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi
Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi
Turkish Journal of Physics
After review the 2D Yang--Mills theories (YM$_2$) and its large--$N$ behaviour, the Generalized 2D Yang--Mills theories (gYM$_2$) and their partition functions on a general two--dimensional Riemann surface are discussed.The large--$N$ behaviour of these models is studied in weak regime, and in strong regime, we restrict ourselves to $\phi^4$ gYM$_2$. We show that this model has a third order phase transition, similar to ordinary YM$_2$ theory.
Noncommutativity In String Theory And Large Extra Dimensions, Farhad Ardalan
Noncommutativity In String Theory And Large Extra Dimensions, Farhad Ardalan
Turkish Journal of Physics
Noncommutativity of space coordinates of string theory are reviewed and are related to the large extra dimension solution of the hierarchy problem.
Kerr Spinning Particle, A. Burinskii
Kerr Spinning Particle, A. Burinskii
Turkish Journal of Physics
We give a brief review of the problems connected with the model of spinning particle based on the Kerr geometry. We consider peculiarities of the Kerr rotating black hole solution in gravity, supergravity and low energy string theory. A non-trivial supergeneralization of the Kerr-Newman solution to broken N=2 supergravity is considered. \par The problem of source of the Kerr geometry is discussed, and we consider some arguments in favor of the supersymmetric Fermi-ball model for the Kerr source based on the Witten $U(1)\times U(\tilde 1)$ field model for superconducting strings.
Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇
Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇
Turkish Journal of Physics
Using the ground state candidates for Hydrophobic-Polar lattice model on a two dimensional square lattice, we exactly enumerate the native states of proteins with length up to 20 for a wide range of energy parameters. We find the reduced set of contact maps, ground state candidates, perfectly stable sequences and designability of configurations.
The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel
The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel
Turkish Journal of Physics
A generic model of a random polypeptide chain, with discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues, reproduces the energy probability distribution of real proteins over a very large range of energies. We show that this system with harmonic interactions, under dissipative dynamics driven by random noise, leads to a distribution of energy states obeying a modified one-dimensional Ornstein-Uhlenbeck process with reflecting boundary conditions, and giving rise to distributions of the Wigner or inverse Gaussian form. A continuum approximation leads to a path integral formulation of the problem. PACS 5.65+b,5.70Ln,87.17.Aa
Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt
Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt
Turkish Journal of Physics
The general solution of $SL(2,{\bf R})/U(1)$ WZNW theory is constructed by a gauge invariant reduction. This is done within both Lagrangian and Hamiltonian frameworks.
Canonical Quantisation Of The Sl(2,R)/ U(1) Gauged Wznw Black Hole Model, Christopher Ford, George Jorjadze, Gerhard Weigt
Canonical Quantisation Of The Sl(2,R)/ U(1) Gauged Wznw Black Hole Model, Christopher Ford, George Jorjadze, Gerhard Weigt
Turkish Journal of Physics
Gauged WZNW models are integrable conformal field theories with non-local canonical free-field transformations. Canonical quantisation requires quantum deformations.
Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour
Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour
Turkish Journal of Physics
A multi-species generalization of the asymmetric simple exclusion process (ASEP) is studied in ordered sequential and sub-lattice parallel updating schemes. In this model, particles hop with their own specific probabilities to their rightmost empty site and fast particles overtake slow ones with a definite probability. Using Matrix Product Ansatz (MPA), we obtain the relevant algebra, and study the uncorrelated stationary state of the model both for an open system and on a ring. A complete comparison between the physical results in these updates and those of random sequential introduced in [20,21] is made.
Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca
Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca
Turkish Journal of Physics
The nature of $SO(3)$ breaking into its closed subgroups and the emergence of nonabelian cosmic strings are discussed. Relevance to GUT breaking and thereby to cosmology is pointed out. Classification of cosmic strings are associated with the affine ADE Lie algebras.
Spinors And Positive Mass, Malcolm Ludvigsen
Spinors And Positive Mass, Malcolm Ludvigsen
Turkish Journal of Physics
As an example of how spinor methods can be applied to the positive-mass theorem, a simple, spinor-based proof of the theorem is presented for the case of a single black hole. Generalisations of the theorem are also discussed.
Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh
Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh
Turkish Journal of Physics
A two-component formulation of the Klein-Gordon equation is used to investigate the cyclic and noncyclic adiabatic geometric phases due to spatially homogeneous (Bianchi) cosmological models. It is shown that no adiabatic geometric phases arise for Bianchi type I models. For general Bianchi type IX models the problem of the adiabatic geometric phase is shown to be equivalent to the one for nuclear quadrupole interactions of a spin. For these models nontrivial non-Abelian adiabatic geometrical phases may occur in general.
From Antibracket To Equivariant Characteristic Classes, Armen Nersessian
From Antibracket To Equivariant Characteristic Classes, Armen Nersessian
Turkish Journal of Physics
We equip the exterior algebra of Riemann manifold by the odd symplectic structure. Then, by its use we construct the equivariant even (pre)symplectic structure, whose Poincare - Cartan invariants of the second structure define the equivariant Euler classes of the surfaces.
Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky
Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky
Turkish Journal of Physics
The dynamics of closed scalar field FRW cosmological models is studied for several types of exponentially and more than exponentially steep potentials. The parameters of scalar field potentials which allow a chaotic behaviour are found from numerical investigations. It is argued that analytical studies of equation of motion at the Euclidean boundary can provide an important information about the properties of chaotic dynamics. Several types of transition from chaotic to regular dynamics are described.
Skyrmions From Harmonic Maps, Wojtek Zakrzewski
Skyrmions From Harmonic Maps, Wojtek Zakrzewski
Turkish Journal of Physics
We describe some relations between solitonic solutions of various models in different dimensions. We present some examples and then concentrate on some of our recent work (performed in collaboration with Ioannidou and Piette) \cite{IPZ} \cite{us2} which shows how some harmonic maps from $S^2$ to $CP^{N-1}$ can be used to find nontrivial spherically symmetric static solutions of the $SU(N)$ Skyrme model in 3 dimensions and to generate some of its low energy field configurations.
The Decay Of A Black Hole As A Quantum Dissipative Process, Carl Wolf
The Decay Of A Black Hole As A Quantum Dissipative Process, Carl Wolf
Turkish Journal of Physics
By considering the decay of a black hole as a result of the interaction of a quantum system with a dissipative vacuum, or in terms of string theory, the interaction of localized string modes with non-local string modes, we demonstrate how the single parameter representing dissipation can be calculated in terms of known fundamental constants. In view of the uncertainty embodied in all the present theories of black hole decay it is suggested that the approach of this note might provide fresh insight to the problem of black hole decay. P.A.C.S.: 98.80-Dr Cosmology
Associations Of X-Ray Binaries With Open Clusters And Supernova Remnants, Eni̇s Tuncer, H. Guseinov, Ü. Kiziloğlu, A. O. Allakhverdiev
Associations Of X-Ray Binaries With Open Clusters And Supernova Remnants, Eni̇s Tuncer, H. Guseinov, Ü. Kiziloğlu, A. O. Allakhverdiev
Turkish Journal of Physics
Searching for X-ray binaries projected on open clusters (OCs) and supernova remnants (SNRs), associations of X-ray binaries with OCs and SNRs in the Galaxy are discussed. Three of the high mass X-ray binaries (HMXBs) and four of the low mass X-ray binaries (LMXBs) are projected on open clusters. Five of HMXBs and six of LMXBs are projected on SNRs. The number of the HMXB projections are less than the LMXBs, which is not expected and is surprising since the objects in this study, except the LMXBs, are all young objects. Such associations help us improve distance and age estimates of …
A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson
A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson
Turkish Journal of Physics
A glancing incidence EXAFS experiment has been carried out with evaporated silver films on glass substrates. Prior to EXAFS data collection, a reflectivity curve was performed from which the critical angle for total external reflection of x-rays from surface were determined. The analysed EXAFS data revealed that there is a reduction in the coordination number and an increase in Debye-Waller factor compared to bulk values. These changes were explained in terms of grain size effect and the surface effects of the silver film.
The Effect Of Potassium Doping On Resistive Transitions And Transport Critical Current Of Bulk Ybco High-Tc Superconductors, S. Çelebi̇, A. Öztürk, İ. Karaca, U. Kölemen
The Effect Of Potassium Doping On Resistive Transitions And Transport Critical Current Of Bulk Ybco High-Tc Superconductors, S. Çelebi̇, A. Öztürk, İ. Karaca, U. Kölemen
Turkish Journal of Physics
We report on observations of the effect of potassium in YBCO (123) high temperature superconductors with nominal composition Y\( _{1-0,2x} \) Ba\( _{2-0.2x} \) K\( _{x} \) Cu\( _{3} \) O\( _{y} \). The electrical resistivity measurements show that the critical temperature T$_{c} \) (R=0) shifted slightly to lower temparature due to the K doping process. This process also decreases the transport critical current density and the activation energy for thermally activated flux flow. The magnetic field dependence of \( j_{c} \) was measured at 77 K after zero field cooling (ZFC) when the applied magnetic field is impressed (ZFCV) …
Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan
Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan
Turkish Journal of Physics
Properties of internal photoemission in a PtSi-Si Schottky junction have been studied. The traditional Fowler plot of a detector's photoyield is found to be nonlinear for values close to the barrier height of the junction. It is shown that the model that takes all scattering mechanisms into account provides a successful description for the experimental results. It is also shown that the photoemission spectrum is independent of temperature in agreement with this model. The properties of detector's ambient influence the photoemission spectrum for wavelength of 3 $\mu$m or less. A strong loss in the detector's response is observed at around …
^{87}Rb Nmr Relaxation And Vortex Dynamics In Rb_3c_{60}, Fügen Tabak, Maurizio Corti̇
^{87}Rb Nmr Relaxation And Vortex Dynamics In Rb_3c_{60}, Fügen Tabak, Maurizio Corti̇
Turkish Journal of Physics
^{87}Rb NMR relaxation measurements in superconducting fullerene Rb_{3}C_{60} for various values of the external field are reported. In the normal state the results are in agreement with T_{1}T= Constant. Below T_{c}, while no evidence of Hebel-Slichter peak is present in temperature dependence of T_{1}^{-1} , maxima are observed in \( T_{2}^{-1} at T=22K characteristic of vortex field fluctuation. T_{1} shows an anomalous field dependence not yet explained.
Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak
Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak
Turkish Journal of Physics
The second order contribution for the relativistic scattering of massless spin-$\frac{1}{2}$ particles from an infinitely long solenoid, in the context of covariant perturbation theory, is calculated and shown to vanish. Thus, Born approximation is consistent for this case as well.
Interaction Between Cesium Chloride Molecules And Metal Atoms Under Coadsorption On A Single Graphite Layer On Iridium, N. M. Nasrullaev
Interaction Between Cesium Chloride Molecules And Metal Atoms Under Coadsorption On A Single Graphite Layer On Iridium, N. M. Nasrullaev
Turkish Journal of Physics
Using the method of continuos flow to investigate the kinetics of reaction between atoms and molecules, the efficiency of substitution reactions (K, Na, Li)+ CsCl is shown to decrease. The efficiency is found to strongly depend on temperature tending to saturation with decreasing temperature. This fact is in accordance with Bonzel's concept.
The Effect Of Various Experimental Parameters On Glow Peaks And Trapping Parameters Of Caf_2:Dy (Tld-200) Crystals, A. Necmeddi̇n Yazici, M. Yakup Hacii̇brahi̇moğlu, Meti̇n Bedi̇r
The Effect Of Various Experimental Parameters On Glow Peaks And Trapping Parameters Of Caf_2:Dy (Tld-200) Crystals, A. Necmeddi̇n Yazici, M. Yakup Hacii̇brahi̇moğlu, Meti̇n Bedi̇r
Turkish Journal of Physics
In the present study, thermoluminescence glow curves of CaF$_{2}$:Dy (TLD-200) crystals have been investigated in detail between the temperature region 300-550 K. The number of peaks and their trapping parameters (E, s and b) have been determined using the computerized glow curve fitting, peak shape and isothermal decay methods. In addition, the effect of storage times at room temperature, dose levels and heating rates on the trapping parameters have been investigated in detail by using computerized glow curve deconvolution method (CGCD) using first and general order kinetic equations.
Optical Properties Of Zns Thin Films, M. Y. Nadeem, Waqas Ahmed
Optical Properties Of Zns Thin Films, M. Y. Nadeem, Waqas Ahmed
Turkish Journal of Physics
Zinc sulfide (ZnS) thin films of different thickness were deposited on Corning 7059 glass substrate at room temperature and high vacuum using resistive heating technique. The film properties investigated include their absorbance / transmittance / reflectance spectra, band gap, refractive index, extinction coefficient, optical conductivity, complex dielectric constant and thickness. The films were found to exhibit high transmittance (60-99\%), low absorbance and low reflectance in the visible / near infrared region up to 1100 nm. However, the absorbance of the films was found to be high in the ultra violet region with peak around 360 nm. The thickness (using quartz …
Thermal Stability Of Fe_{85.5}B_{14.5} Metallic Glass, Asghari Maqsood, Ashfaq Ahmad
Thermal Stability Of Fe_{85.5}B_{14.5} Metallic Glass, Asghari Maqsood, Ashfaq Ahmad
Turkish Journal of Physics
The thermal stability and crystallization behaviour of metallic glass Fe\( _{85.5} \)B\( _{14.5} \) were investigated by Dynamic Temperature Resistivity Measurement (DTRM) technique from room temperature to 1050K in forward and reverse mode at a heating rate of 40 K/hr. The slope of Resistivity-Temperature-Curve (RTC) changes sign and magnitude at the temperature where the transition takes place. Differential Thermal Analysis (DTA) was carried out at the heating rates of 10, 20, 30 \& 40 K/min. A comparison of the results of DTRM and DTA measurements shows that crystallization in this alloy is two-stage process. Activation energy for two crystallization steps …
The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali
The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali
Turkish Journal of Physics
The magnetic properties and redetermination of crystal structure of copper(II) acetate monohydrate have been studied. The copper(II) centers are separated by 2.617(1) \AA \ and antiferromagnetically coupled (-2J = 292.2 cm$^{-1}$), which follows from temperature-dependent magnetic susceptibility measurements in the temperature range 4.2 to 300 K. The magnetic moment at 300 K is about 2.1 Bohr magnetons while 0.1 Bohr magnetons at 4.2 K. The magnetic susceptibility is at a maximum near 250 K and decreases rapidly as the temperature is lowered to liquid helium temperature.
Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki
Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki
Turkish Journal of Physics
Junctions were fabricated in vacuum of about $10^{-5}$ Torr by thermal evaporation of Sb or Bi onto chemically etched $p$-type silicon (100) substrates. The electrical properties were studied by current voltage (I-V) measurements. Some of the Sb and Bi junctions were heated-treated for $\frac{1}{2}$ hr at 200 and 150^oC, respectively. The barrier height (BH) was equal to 0.64 eV for both as-deposited and heat-treated Sb junctions, while it was 0.56 and 0.74 eV for as-deposited and heat-treated Bi Junctions, respectively. These observatimons indicate that for Sb junctions, annealing at a temperature of 200^oC resulted only in partial elimination of any …