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Articles 1111 - 1140 of 1382
Full-Text Articles in Physical Sciences and Mathematics
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.
On The Duality Of Quantum Liouville Field Theory, L. O'Raifeartaigh, J. M. Pawlowski, V. V. Sreedhar
On The Duality Of Quantum Liouville Field Theory, L. O'Raifeartaigh, J. M. Pawlowski, V. V. Sreedhar
Turkish Journal of Physics
It has been found empirically that the Virasoro centre and 3-point functions of quantum Liouville field theory with potential $e^{2b\phi(x)}$ and external primary fields exp($\alpha\phi(x)$) are invariant with respect to the duality transformations $\hbar \alpha\rightarrow q-\alpha$ where $q=b^{-1}+b$. The steps leading to this result (via the Virasoro algebra and 3-point functions) are reviewed in the path-integral formalism. The duality stems from the fact that the quantum relationship between the $\alpha$ and the conformal weights $\Delta_\alpha$ is two-to-one. As a result the quantum Liouville potential may actually contain two exponentials (with related parameters). It is shown that in the two-exponential theory …
Gauge Transformations In General Relativity - A Report, L. C. Shepley, J. M. Pons, D. C. Salisbury
Gauge Transformations In General Relativity - A Report, L. C. Shepley, J. M. Pons, D. C. Salisbury
Turkish Journal of Physics
We take as our basic principle that the Lagrangian and the Hamiltonian formulations of general relativity should be equivalent. It is then possible to choose the gauge transformations so as to be projectable under the Legendre map from configuration-velocity space (the tangent bundle) to phase space (the cotangent bundle). This projectability requirement then implies that gauge transformations in general relativity (we study in particular spacetimes with a Yang-Mills field) must depend in a specific way on the lapse and shift of the metric. This talk outlines the arguments and presents some of the results of the application of these principles.
Coherent States For The Hydrogen Atom, Nuri̇ Ünal
Coherent States For The Hydrogen Atom, Nuri̇ Ünal
Turkish Journal of Physics
We obtained the coherent states for the hydrogen atom by transforming the problem onto the four oscillators in the parametric time at the classical level and quantizing these oscillators. We showed that for the coherent states the mean values of the physical position of the electron satisfy the Keplerian ellipsis and the dispersions of them oscillate in the parametric time.
Parameterized Absolute Parallelism: A Geometry For Physical Applications, Mamdouh Ishaac Wanas
Parameterized Absolute Parallelism: A Geometry For Physical Applications, Mamdouh Ishaac Wanas
Turkish Journal of Physics
Absolute parallelism (AP) geometry is frequently used for physical applications. Although it is wider than the Riemannian geometry, it has two main defects. The first is that its path equation does not represent physical trajectories of any test particle. The second is the identical vanishing of its curvature tensor. The present work shows that parameterizing this geometry would solve the two problems. Furthermore, the resulting parameterized (AP)-structure is more general than both the conventional (AP)-structure and the Riemannian structure. Also, it is shown that it can be reduced to one or the other, of these two geometric structures, in some …
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.
Time Evolution Of Fast Particles During Decay Of Hadronic Systems, Mohamed Tarek Hussein, Nabila Mohamed Hassan, Nagla El-Harby
Time Evolution Of Fast Particles During Decay Of Hadronic Systems, Mohamed Tarek Hussein, Nabila Mohamed Hassan, Nagla El-Harby
Turkish Journal of Physics
A phenomenological model is presented based on the formation of a nuclear thermodynamic system during the collision of intermediate and high energy heavy ions. The formulation and the dynamic picture are determined by solving the Vlasov equation. The solution is dressed in the form of a power series the first term of which being the equilibrium distribution in phase space. The rest, are time dependent perturbation terms due to the multiple strong interactions inside the system. The temperature gradient and the derivatives of the phase function are calculated. The time dependence of the angular emission of the produced particles is …
The Radius Cutoff For Relativistic Clusters, M. Hafizi
The Radius Cutoff For Relativistic Clusters, M. Hafizi
Turkish Journal of Physics
In this work we consider an isothermic relativistic kinetic gas under relativistic conditions, as a model for high center density galaxies. We apply the radius cutoff of the Emden type, in order to remove infinities. Numerically we find some theoretical configurations with very high values of masses concentrated in small volumes. Profiles of some thermodynamic quantities such as density, presure, will be independent from the choice of radius cutoff, whereas temperature and gravitational potential depend essentially on the cutoff value.
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 …
Positron Annihilation And Xrd Studies On Deformed Al-Alloys With Low Concentration Of Mg, Emad A. Badawi, M. A. Abdel-Rahman, S. A. Mahmoud, A. A. Ramadan
Positron Annihilation And Xrd Studies On Deformed Al-Alloys With Low Concentration Of Mg, Emad A. Badawi, M. A. Abdel-Rahman, S. A. Mahmoud, A. A. Ramadan
Turkish Journal of Physics
Positron behaviour at grain boundaries is characterized by their bulk diffusibility D, their bulk free lifetime $\tau_f$ and their trapped lifetime $\tau_t$ ($\tau_t > \tau_f).$ Al-Mgx samples (x = 0-1.4 at \%) have been homogenized at 573 K for 12 hours. The mean lifetime, as (indirectly) measured at various concentrations, show a good fitting with Sigmodel giving $\tau_t$ = 180.664 ps and $\tau_{f}$ = 163.9 ps. The mean lifetime was found to vary exponentially with the degree of deformation. The XRD study showed that preferred orientation occurred at degrees of deformation $>$ 32 \%, whereas the peak intensity then increases …
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.
Ferromagnetic Transitions In Ni-Mn Alloys, F. Boakye, R. K. Nkum
Ferromagnetic Transitions In Ni-Mn Alloys, F. Boakye, R. K. Nkum
Turkish Journal of Physics
Ferromagnetic transitions in nickel and nickel-manganese alloys have been studied using resistivity-temperature measurements from 800 to 77 K. The results establish the transition temperature of nickel as 610 K and the transition temperature is shifted to lower values as the concentration of Mn in the alloy is increased. Analysis of the resistivity results near the ordering temperature \( (T
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) …
^{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.
Topological Unitarity Identities In The Theory Of Scalar Charged Particles Interacting Through A Pure C-S Gauge Field, Müge Boz, V. Ya Fainberg
Topological Unitarity Identities In The Theory Of Scalar Charged Particles Interacting Through A Pure C-S Gauge Field, Müge Boz, V. Ya Fainberg
Turkish Journal of Physics
Starting from the theory of relativistic scalar charged particles interacting via C-S field, it is verified that the gauge invariant sum of the imaginary parts of all Feynman diagrams with C-S photon lines on the mass shell vanish.
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.
Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven
Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven
Turkish Journal of Physics
The fragmentation mechanism of the super heated Ni4 cluster is studied by employing the microcanonical molecular dynamics simulations and an empirical model potential. Ni$_{4}$ cluster is heated up above the bulk Ni evaporation point temperature and then classical trajectory analysis as well as RRK theory are used to calculate survival probability, evaporation rate, average kinetic energy release and dissociation energy.
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 …
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.
Characterization Of Phenanthrene Single Crystals, M. Tariq Bhatti, Anwar Manzoor Rana, Mazhar Ali, Gul N. Shahid, M. Saleh
Characterization Of Phenanthrene Single Crystals, M. Tariq Bhatti, Anwar Manzoor Rana, Mazhar Ali, Gul N. Shahid, M. Saleh
Turkish Journal of Physics
Single crystals of phenanthrene were successfully grown from melt using Bridgeman Crystal Growth System Type 365. The starting material was purified by sublimation and zone refining techniques in specially designed crystal growth tubes. Phenanthrene single crystals grow with the plane of maximum growth corresponding to the ab-crystallographic plane, and cleave readily in this plane. The optical absorption spectra of phenanthrene single crystals and phenanthrene crystals dissolved in benzene, alcohol and acetone solutions were studied in the wavelength range (200 - 400 nm). The optical excitations i.e., \( \pi - \pi^{*} \) transitions, are attributed to the weak and strong optical …
Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye
Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye
Turkish Journal of Physics
Antiferromagnetic transition in $\alpha$-Mn-Fe alloys has been studied using resistivity-temperature measurements from 300 to 1.5 K. The results indicate that the transition temperature $T_N$ of the samples studied increases with increasing Fe concentration. This suggests that the N\'{e}el temperature is affected by Fe. Also, Fe plays a significant role in the local disorder on the magnetic moment of the ions in the complex manganese structure.
Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan
Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan
Turkish Journal of Physics
The radioluminescent proporties of silver-doped cadmium sulphide, CdS(Ag), crystals excited by 5.5 MeV $ \alpha $-particles from an $ ^{241}$Am radioactive source have been investigated. The emission spectra, decay profiles and thermal quenching curves were obtained accurately at temperatures between 80 K and 300 K. Two main radioluminescent emission bands centered at about 5760 \AA\ and 5940 \AA\ were observed. Their decay curves were found to be fast and nonexponential. From the thermal quenching of radioluminescence, the activation energies of centers responsible for these emissions were determined. The results are interpreted as the radioluminescence is possibly due to donor-acceptor pair …
Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab
Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab
Turkish Journal of Physics
Spinel nickel manganite has been synthesized using ceramic technique, from (2MnO$_{2}$+NiO) mixture reduced using LiAlH$_{4}$. Powder X-ray diffractometry (XRD) indicates the formation of cubic spinel (a=8.33 A^o), while IR absorption spectral features are rather broad, though similar to those of spinel. The d.c. electrical conductivity of the ceramic is much smaller than that reported for NiMn$_{2}$O$_{4}$. Even though the band gap remains the same, when the sintering temperature is increased from 950^oC to 1100 ^oC, all other changes are insignificant except that the porosity and particle size nearly halve. The characteristics of the system are discussed in terms of `lithiation'.
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 …
Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik
Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik
Turkish Journal of Physics
The normal reflectance of single crystal Si was measured at 0.5 5.6 eV range by unpolarized light. Optical parameters of Si were determined from this reflectance data by using two different methods: oscillator fit procedure and Kramers-Kronig analysis. The refractive index, extinction coefficient and the real and imaginary parts of complex dielectric constant obtained by these two methods were compared. A good agreement was found between two methods. Furthermore, the optical parameters so obtained seem to be in a satisfactory agreement with the literature.
Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak
Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak
Turkish Journal of Physics
In this study, the Kajiwara model has been applied to Cu-14.8at.\%Sn alloy with good agreement with experimental results. For this alloy, the austenite phase has a body centered cubic (bcc) lattice and the martensite phase has a monoclinic 9R superlattice. Using the lattice parameters of both phases, the calculated habit plane indices, magnitude of the lattice invariant shear and orientation relationships, have been compared with the observed results for this alloy.
A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten
A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten
Turkish Journal of Physics
Product operator formalism is widely used for analytical description of multiple-pulse NMR experiments for weakly coupled spin systems. 3D J-resolved NMR spectroscopy is widely used in order to resolve the chemical shift along one axis and spin-spin coupling parameters along the two other axis. In this study, product operator theory is used for analytical description of heteronuclear 3D J-resolved NMR spectroscopy for the \( IS_nK_m (I=1/2, S=1/2, K=1/2; n=1,2, m=1,2,3) \) spin system.
The Extended Hybrid Model For Optical Phonon Confinement, C. R. Bennett, B. K. Ridley, N. A. Zakhleniuk, M. Babiker
The Extended Hybrid Model For Optical Phonon Confinement, C. R. Bennett, B. K. Ridley, N. A. Zakhleniuk, M. Babiker
Turkish Journal of Physics
The theory of optical phonons and their confinement in heterostructures is reviewed with analogies made to the theory of acoustic phonons. The dielectric continuum (DC) model is obtained when bulk dispersion is ignored and the hybrid model is found when dispersion is included. The issue of boundary conditions is investigated and the solutions are shown with comparisons made using electron-phonon scattering.
Experimental Determination Of \Beta And \Gamma Critical Exponents In The Sol-Gel Phase Transition By Using Steady-State Fluorescence Technique, Y. Yilmaz, Ö. Pekcan
Experimental Determination Of \Beta And \Gamma Critical Exponents In The Sol-Gel Phase Transition By Using Steady-State Fluorescence Technique, Y. Yilmaz, Ö. Pekcan
Turkish Journal of Physics
The gelation of methyl methacrylate and ethylene glycol dimethacrylate was studied using the steady-state fluorescence technique. Samples with various crosslinker densities were prepared and sol-gel phase transitions were observed at various temperatures. Percolation theory was employed to interpret the results. For all samples the gel fraction and the average cluster size exponents, \beta and \gamma, were measured and found to be around 0.42 and 1.7 respectively. These values show excellent agreement with theoretical and simulation results.