Showing papers in "Canadian Journal of Physics in 2009"
TL;DR: In this article, it was shown that near the Planck scale, the Heisenberg uncertainty principle should be replaced by the generalized uncertainty principle (GUP) in quantum gravity.
Abstract: Various theories of quantum gravity argue that near the Planck scale, the Heisenberg uncertainty principle should be replaced by the so called generalized uncertainty principle (GUP). We show that ...
237 citations
TL;DR: In this article, the contribution of buoyancy along with viscous dissipation on the convective transport in the boundary-layer region is analyzed in opposing and assisting flow situations, and a parametric study of the mixed convection parameter ξ, the micropolar parameter Δ, the Eckert number Ec, the parameter of temperature distribution n, and Prandtl number Pr is conducted.
Abstract: Micropolar boundary-layer flow and heat transfer characteristics associated with a heated exponential stretching continuous sheet being cooled by a mixed convection flow are examined. The relevant heat transfer mechanisms are of interest in a wide variety of practical applications such as hot rolling, continuous casting, extrusion, and drawing. The wall temperature and stretching velocity are assumed to vary according to specific exponential forms. The contributions of buoyancy along with viscous dissipation on the convective transport in the boundary-layer region is analyzed in the opposing and assisting flow situations. Local similarity solutions are obtained for the boundary-layer equations governing the problem. A parametric study of the mixed convection parameter ξ, the micropolar parameter Δ, the Eckert number Ec, the parameter of temperature distribution n, and Prandtl number Pr is conducted and a representative set of numerical results for the velocity, angular velocity, temperature profiles, loca...
139 citations
TL;DR: In this article, the search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ √ n/mp) was studied.
Abstract: The search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ = me/mp) i...
59 citations
TL;DR: In this paper, variable viscosity and variable thermal conductivity of an electrically conducting non-Newtonian power-law fluid with variable flow and heat transfer were studied.
Abstract: The present paper is concerned with the study of variable viscosity and variable thermal conductivity on the flow and heat transfer of an electrically conducting non-Newtonian power-law fluid withi...
59 citations
TL;DR: In this paper, the potential plateaus of the coexisting phase regions, obtained using the projector augmented wave (PAW) method, have an average absolute error of 31 mV with respect to experiment.
Abstract: An investigation of Li–Si alloys using density functional theory is presented. Various calculation methods and pseudopotentials are analyzed to best reproduce the potential versus composition curve of a Li/LixSi electrochemical cell at high temperature using the experimentally observed Li–Si phases. Total energy calculations, structural optimizations, and bulk modulus estimations were completed for the Si, Li12Si7, Li7Si3, Li13Si4, Li15Si4, Li22Si5, and Li phases. The potential plateaus of the co-existing phase regions, obtained using the projector augmented wave (PAW) method, have an average absolute error of 31 mV with respect to experiment. The Li7Si3 and Li15Si4 compositions are discussed and the Li15Si4 phase is found to have a lower bulk modulus relative to the other phases.
58 citations
TL;DR: In this article, the exact solutions of the DKP oscillator for spin-0 particles have been studied in noncommutative phase space, and the results show that due to the non-commutativity effect, the energy spectrum of the KDP oscillators is no longer degenerate.
Abstract: The exact solutions of the Duffin–Kemmer–Petiau (DKP) oscillator for spin-0 particles have been studied in noncommutative phase space. The results show that due to the noncommutative effect, the energy spectrum of the DKP oscillator for spin-0 particles is no longer degenerate. In addition, we obtain the nonrelativistic limit of the energy spectrum.
50 citations
TL;DR: In this article, 39 high-resolution spectra of pure and air-broadened CO2 recorded at temperatures between 215 and 294 K were analyzed using a multispectrum nonlinear least-squares technique.
Abstract: In this study, 39 high-resolution spectra of pure and air-broadened CO2 recorded at temperatures between 215 and 294 K were analyzed using a multispectrum nonlinear least-squares technique to deter...
47 citations
TL;DR: In this paper, a Korteweg-de vries equation was derived for the ion acoustic wave in a weakly relativistic magnetized electron-positron-ion warm plasma.
Abstract: A theoretical investigation was made for the ion acoustic wave in a weakly relativistic magnetized electron-positron-ion warm plasma. A Korteweg-de vries equation (KdV) is derived by using a standard reductive perturbation method. It is found that the presence of ion temperature (σ), ratios of positron-to-electron density (β), electron-to-positron temperature (α), and relativistic factor (Ur) significantly modify solitonic behavior. The authors observed that these parameters considerably change the amplitude and width of the solitary wave.
38 citations
TL;DR: In this paper, H2O pressure-broadened halfwidths were obtained for 182 lines of CO2 in the 2250-2390 cm-1 region using Bruker IFS-125HR at the Jet Propulsion Laboratory.
Abstract: To support remote sensing of carbon dioxide in the troposphere, H2O pressure-broadened half-widths were obtained for 182 lines of CO2 in the 2250–2390 cm–1 region. For this, six spectra of CO2 were recorded at 0.003 89 cm–1 resolution using a Bruker IFS-125HR at the Jet Propulsion Laboratory. The absorption cell length was 6.14 cm, and the water pressures ranged from 20.1 to 26.5 torr (1 torr = 133.322 4 Pa) near room temperatures. Partial pressures of the species in the mixtures were determined by measuring selected line intensities in the v3 band of CO2 and the v2 band of H2O. Sample temperatures were validated by deriving rotational temperature from the v3 and v2 + v3 – v2 intensities of 12CO2 and those of CO (1–0). Positions, intensities, and half-widths were retrieved spectrum by spectrum using a nonlinear least-squares line-fitting algorithm, employing a standard Voigt line shape profile and an instrumental line shape consisting of a sinc function with aperture correction. Half-widths obtained for b...
37 citations
TL;DR: This paper examined the effects of computer-based Interactive Lecture Experiments (ILEs) in a large introductory physics course on student academic achievement and attitudes towards physics and found that ILEs build on interactive lecture demonstrations by requiring students to analyze data during and after lecture demonstrations.
Abstract: This paper examines the effects of computer-based Interactive Lecture Experiments (ILEs) in a large introductory physics course on student academic achievement and attitudes towards physics. ILEs build on interactive lecture demonstrations by requiring students to analyze data during and after lecture demonstrations. Academic achievement was measured using the Force Concept Inventory (FCI) and final examinations' grades; and student attitudes were measured using a Colorado Learning Attitudes about Science Survey (CLASS). FCI results showed a general positive shift (about average for an interactive course) but could not detect improvements in student understanding of specific topics addressed by ILEs. However, open-ended questions on the final exam showed differences between sections on topics that were addressed by ILEs. Attitude survey results showed a negative shift in student attitudes over the semester, which is a typical result for an introductory physics course. This finding suggests that ILE pedago...
35 citations
TL;DR: In this article, an effective master equation and quantum trajectory equation for multiple qubits in a single resonator and in the large resonator decay limit were derived for homodyne measurem...
Abstract: In this paper we derive an effective master equation and quantum trajectory equation for multiple qubits in a single resonator and in the large resonator decay limit. We show that homodyne measurem...
TL;DR: In this paper, the Hirota bilinear method is applied to show that coupled KdV and coupled KP equations are completely integrable, and multiple singular-soliton solutions are derived for each system.
Abstract: In this work we study two systems of coupled KdV and coupled KP equations. The Hirota bilinear method is applied to show that these two systems are completely integrable. Multiple-soliton solutions and multiple singular-soliton solutions are derived for each system. The resonance phenomenon is examined as well.
TL;DR: In this paper, it was shown that the solutions of the Duffin-Kemmer-Petiau equation for a pseudoscalar potential step in (1+1) dimensions by Abdelmalek Boumali has a number of misconceptions.
Abstract: It is shown that the paper Solutions of the Duffin–Kemmer–Petiau equation for a pseudoscalar potential step in (1+1) dimensions by Abdelmalek Boumali has a number of misconceptions.
TL;DR: In this paper, the authors consider the possibility of realizing inflation in nonlocal field theories containing infinitely many derivatives and examine the inflationary dynamics and phenomenology of such theories, showing that nonlocal inflation can proceed even when the potential is naively too steep and generically predicts large nonGaussianity in the cosmic microwave background.
Abstract: We consider the possibility of realizing inflation in nonlocal field theories containing infinitely many derivatives. Such constructions arise naturally in string field theory and also in a number of toy models, such as the p-adic string. After reviewing the complications (ghosts and instabilities) that arise when working with high-derivative theories, we discuss the the initial value problem and perturbative stability of theories with infinitely many derivatives. Next, we examine the inflationary dynamics and phenomenology of such theories. Nonlocal inflation can proceed even when the potential is naively too steep and generically predicts large non-Gaussianity in the cosmic microwave background.
TL;DR: In this paper, a few properties of the nonminimal vector interactions in the Duffin-Kemmer-Petiau theory are revised, and it is shown that the space component plays a crucial role in non-linear vector interactions.
Abstract: A few properties of the nonminimal vector interactions in the Duffin–Kemmer–Petiau theory are revised. In particular, it is shown that the space component of the nonminimal vector interaction plays...
TL;DR: In this paper, peristaltic transport of a Carreau fluid in an asymmetric channel is studied theoretically under zero Reynolds number and longwavelength approximation for both slip and no-slip flow.
Abstract: In this paper, peristaltic transport of a Carreau fluid in an asymmetric channel is studied theoretically under zero Reynolds number and long-wavelength approximation for both slip and no-slip flow...
TL;DR: The two optically forbidden lines of atomic oxygen, O(1S−1D) at 557.7 and O( 1S−3P) at 297.2, serve as important diagnostics in atmospheric, planetary, and cometary studies as discussed by the authors.
Abstract: The two optically forbidden lines of atomic oxygen, O(1S–1D) at 557.7 nm and O(1S–3P) at 297.2 nm, serve as important diagnostics in atmospheric, planetary, and cometary studies. Originating from the same upper state, the emission brightness ratio, B(557.7)/B(297.2), must necessarily be constant. The reported emission ratio of these two lines from both theoretical and experimental investigations varies by approximately a factor of two. These two emissions are observed simultaneously in auroral spectra by the OSIRIS spectrograph on the Odin spacecraft, offering another opportunity to perform the ratio measurement. Because of the considerable wavelength separation between these two atomic lines, precise instrumental relative response calibrations can be problematic. To maintain accurate on-orbit spectral calibrations, an atmospheric radiation model with multiple Rayleigh scatter is employed to constantly track instrumental response. An example of a calibrated single bright auroral spectrum over the full OSI...
TL;DR: In this article, an accurate knowledge of the electronic properties of dipolar molecules is used for obtaining ultracold samples, which is a current challenge in the field of molecular physics.
Abstract: Obtaining ultracold samples of dipolar molecules is a current challenge, which requires an accurate knowledge of their electronic properties to guide the ongoing experiments. Alkali hydride molecul...
TL;DR: In this paper, the Klein-Gordon equation in the presence of a spatially one-dimensional Hulthen potential is solved exactly and the scattering solutions are obtained in terms of hypergeometric functions.
Abstract: The Klein–Gordon equation in the presence of a spatially one-dimensional Hulthen potential is solved exactly and the scattering solutions are obtained in terms of hypergeometric functions. The transmission coefficient is derived by the matching conditions on the wave functions and the conditions for the existence of transmission resonances are investigated. It is shown how the zero-reflection condition depends on the shape of the potential.
TL;DR: A review of measurements involving the K-shell (np → 1s) transitions of hydrogen-like ions is given in this paper, which indicates an apparent bias toward wanting to agree with calculations.
Abstract: A review is given of measurements involving the K-shell (np → 1s) transitions of hydrogenlike ions. In many experiments carried out, for example, on electron-beam ion traps and tokamaks, the calculated energies of the Lyman-series lines are utilized as calibration standards for measuring the energies of lines from more complex ions. Examples given include measurements of the transition energies of L-shell lines in neonlike ions. The Lyman lines of low-Z ions are also used as a bootstrap for measuring the contributions of quantum electrodynamics (QED) in very high-Z ions, such as U81+ and U89+. The lowest energy member of the Lyman series, Lyman-α, is commonly the target of absolute-energy measurements so as to test the reliability of the calculations of atomic structure in general and of the 1s QED terms in particular. A review of 42 measurements of 1s QED measurements indicates an apparent bias toward wanting to agree with calculations.PACS Nos.: 32.30.Rj, 31.30.Jv, 12.20.–m
TL;DR: Cascading gravity as discussed by the authors is an explicit realization of the idea of degravitation, where gravity behaves as a high-pass filter, and it relies on the presence of at least two infinite extra dimensions while our world is confined on a fourdimensional brane.
Abstract: Cascading gravity is an explicit realization of the idea of degravitation, where gravity behaves as a high-pass filter. This could explain why a large cosmological constant does not backreact as much as anticipated from standard General Relativity. The model relies on the presence of at least two infinite extra dimensions while our world is confined on a four-dimensional brane. Gravity is then four-dimensional at short distances and becomes weaker and weaker at larger distances.
TL;DR: In this article, depth-dependent composition changes were investigated as guides to monitor the selenization kinetics in a ZnS sprayed thin film, and the spectral analysis was carried out in the region from 400 to 1800 nm.
Abstract: In this study, ZnSSe epilayers were grown on (111) ZnS sprayed thin films. The spectral analysis was carried out in the region from 400 to 1800 nm. Analyses of the transmittance and (or) reflectance spectra indicate a decrease of the band gap energy value Eg with selenization. As the selenization process changes the structure and property of prepared materials and therefore has a direct effect on their physical properties, one of the concerns of this paper is to investigate the depth-dependent composition changes as guides to monitoring the selenization kinetics. Photothermal, atomic force microscopy (AFM), and X-ray diffraction (XRD) investigations have also been carried out.
TL;DR: In this article, high-resolution lines in the CO2 fundamental band of the rovibrational spectrum of He2-CO2 have been observed using a tunable infrared laser to probe a pulsed supersonic jet expansion.
Abstract: Additional high-resolution lines in the ν3 CO2 fundamental band of the rovibrational spectrum of He2-CO2 have been observed using a tunable infrared laser to probe a pulsed supersonic jet expansion. The ro-vibrational spectrum was calculated using Euler angles and five vibrational coordinates that specify the positions of the He atoms with respect to the CO2 molecule, a product basis, and a Lanczos eigensolver. Rotational states with J = 0, 1, 2, and 3 associated with the vibrational ground state and different states (νt) of the torsional motion of the two He atoms about the CO2 axis are identified and assigned. The assignment is consistent with having different principle axis orientiations in νt = 0 and νt = 1 states. Δνt = 1 infrared transistions are forbidden due to the symmetry of CO2, but Δνt = 1 microwave transistions are possible. Theoretical line positions and intensities are predicted. Good agreement between experiment and theory was obtained. The calculated energy levels and intensities were cru...
TL;DR: In this article, a rotationally-resolved vibrational spectra of three bands related to the lowest frequency vibration of the five-membered heterocycle pyrrole (C4H4NH) have been recorded using infrared light from the Canadian Light Source synchrotron as the source.
Abstract: Rotationally-resolved vibrational spectra of three bands related to the lowest frequency vibration of the five-membered heterocycle pyrrole (c-C4H4NH) have been recorded using infrared light from the Canadian Light Source synchrotron as the source. The N-H out-of-plane wagging fundamental band ν16 (474.6 cm–1) was recorded with 0.001 cm–1 resolution along with the first hot band 2ν16–ν16 (488.1 cm–1). Both are governed by c-type selection rules. The first overtone 2ν16 (962.7 cm–1) was recorded with 0.0013 cm–1 resolution and has a-type rotational structure. A total of 9103 lines were assigned and included in a simultaneous fit of all three bands. The band origins and excited state rotational parameters were well-determined using Watson’s S-reduced Hamiltonian, Ir representation as seen by the low rms error of the global fit: 0.000 172 cm–1.
TL;DR: In this paper, the transformation properties of ELKO spinors under charge conjugation, parity, and time reversal were investigated, and it was shown that they are not eigenspinors of the helicity operator and satisfy the same (anti)commutation relations as Dirac spinors.
Abstract: We review the transformation properties of ELKO spinors (Eigenspinoren des Ladungskonjugationsoperators) under charge conjugation, parity, and time reversal. Our calculations confirm that ELKO spinors are not eigenspinors of the helicity operator and satisfy \mathop {\left( {CPT} \right)}
olimits^2 = - \dsi which identifies them as a representation of a nonstandard Wigner class. However, we find that ELKO spinors transform symmetrically under parity instead of the previously assumed asymmetry. Furthermore, we demonstrate that ELKO spinors transform asymmetrically under time reversal, which is opposite to the previously reported symmetric behaviour. These changes affect the (anti)commutation relations that are satisfied by the operators acting on ELKO spinors. We are also able to show that ELKO spinors actually satisfy the same (anti)commutation relations as Dirac spinors, even though they belong to two different representations.
TL;DR: The visible and near infrared spectrum produced by the NO + O → NO2 + hv chemiluminescent reaction has been detected in the upper mesospheric dark polar regions by OSIRIS on the Odin spacecraft as mentioned in this paper.
Abstract: The visible and near infrared continuum spectrum produced by the NO + O → NO2 + hv chemiluminescent reaction has been detected in the upper mesospheric dark polar regions by OSIRIS on the Odin spacecraft. Averaged observed NO2 emission spectral shapes are obtained by spectrally resolving the NO + O continuum from the blended strong upper mesospheric OH vibration–rotation airglow bands. The observed continuum spectral shape when compared with laboratory measurements is shifted to lower wavelengths by approximately 20 nm in the steeply sloped 400 to 500 nm region. The observed laboratory continuum spectral shape for upper mesospheric ambient pressure is presented for reference over the 400 to 800 nm region. An example of an NO2 continuum volume emission-rate altitude profile derived from a single OSIRIS limb scan is also included. Limb radiances up to 3 × 109 photons cm–2 nm–1 s–1 are observed at the peak of the NO2 continuum corresponding to total volume emission rates of approximately 2 × 104 photons cm–3...
TL;DR: In this paper, a one-dimensional model of the generalized magneto-viscoelasticity with two relaxation times in a perfect conducting medium is established, where the state space approach is adopted for the solution of one-dimensions problems for any set of boundary conditions.
Abstract: A one-dimensional model of the two-temperature generalized magneto-viscoelasticity with two relaxation times in a perfect conducting medium is established. The state space approach is adopted for the solution of one-dimensional problems for any set of boundary conditions. The resulting formulation together with the Laplace transform techniques are applied to a specific problem of a half-space subjected to thermal shock and traction-free surface. The inversion of the Laplace transforms is carried out using a numerical approach. Numerical results are given and illustrated graphically for the problem. Some comparisons have been shown in figures to estimate the effects of the temperature discrepancy and the applied magnetic field.
TL;DR: In this article, the B-spline basis set method was applied to determine the rovibrational eigenspectrum of diatomic molecules, and particular attention was paid to a challenging numerical task of an accurate and effici...
Abstract: The B-spline basis-set method is applied to determining the rovibrational eigenspectrum of diatomic molecules. Particular attention is paid to a challenging numerical task of an accurate and effici...
Abstract: A brief review of the search for variation of the fine-structure constant in quasar absorption spectra is presented. Special consideration is given to the role of atomic calculations in the analysi...
TL;DR: In this article, many-electron quantum electrodynamic (QED) effects for the 4s2 1S0−4s4p 1P1 transition in high-Z Zn-like ions with Z = 70, 74, 76, 79, 82, 83, 90, and 92 were analyzed.
Abstract: We report calculations of many-electron quantum electrodynamic (QED) effects for the 4s2 1S0–4s4p 1P1 transition in high-Z Zn-like ions with Z = 70, 74, 76, 79, 82, 83, 90, and 92. When combined wi...