scholarly journals Perturbation of the Non-Radial Oscillations of a Gaseous Star by an Axial Rotation, a Tidal Action or a Magnetic Field

1974 ◽  
Vol 59 ◽  
pp. 197-198
Author(s):  
P. Smeyers
Keyword(s):  
Magnetic Field ◽  
Homogeneous Model ◽  
Axial Rotation ◽  
Second Order ◽  
Third Order ◽  
Polytropic Model ◽  
Rotational Perturbation ◽  
Tidal Perturbation ◽  
Approximate Expressions ◽  
Gaseous Star

The study of the linear and adiabatic oscillations of a gaseous star gives rise to an eigenvalue problem for the pulsation σ, if perturbations proportional to eiσt are considered. In the presence of a rotation, a tidal action or a magnetic field, the equations are not separable in spherical coordinates. To get approximate expressions for the influence of these factors on the non-radial oscillations of a star, the author and his collaborators J. Denis and M. Goossens have used a perturbation method (Smeyers and Denis, 1971; Denis, 1972; Goossens, 1972; Denis, 1973). Their procedure corresponds to a generalization of the method proposed by Simon (1969) to study the second order rotational perturbation of the radial oscillations of a star.Two types of perturbations are taken into account: volume perturbations due to the local variations of the equilibrium quantities and to the presence of a supplementary force in the equation of motion (Coriolis force, Lorentz force); surface perturbations related to the distortion of the equilibrium configuration and to the change of the condition at the surface in the presence of a magnetic field. The resulting expressions are accurate up to the second order in the angular velocity in the case of a rotational perturbation, to the third order in the ratio of the mean radius of the primary to the distance of the secondary in the case of a tidal perturbation, and to the second order in the magnetic field in the case of a perturbing magnetic field. These expressions can in principle be applied to any mode.Numerical results have been obtained for a homogeneous model and for a polytropic model n = 3. In particular, the splitting of the frequencies of the fundamental radial mode and of the f-mode belonging to l = 2 and m = 0 has been studied for the critical value of y, in the case of a component of a synchronously rotating binary system.

Bulk Contributions Modulate the Sum-Frequency Generation Spectra of Interfacial Water on Model Sea-Spray Aerosols

2018 ◽  
Author(s):  
Sandeep K. Reddy ◽  
Raphael Thiraux ◽  
Bethany A. Wellen Rudd ◽  
Lu Lin ◽  
Tehseen Adel ◽  
...  
Keyword(s):  
Single Layer ◽  
Sum Frequency Generation ◽  
Second Order ◽  
Interfacial Structure ◽  
Sea Spray ◽  
Third Order ◽  
Systematic Analysis ◽  
Sum Frequency ◽  
Structure Of Water ◽  
Frequency Generation

Vibrational sum-frequency generation (vSFG) spectroscopy is used to determine the molecular structure of water at the interface of palmitic acid monolayers. Both measured and calculated spectra display speci c features due to third-order contributions to the vSFG response which are associated with nite interfacial electric potentials. We demonstrate that theoretical modeling enables to separate the third-order contributions, thus allowing for a systematic analysis of the strictly surface-sensitive, second-order component of the vSFG response. This study provides fundamental, molecular-level insights into the interfacial structure of water in a neutral surfactant system with relevance to single layer bio-membranes and environmentally relevant sea-spray aerosols. These results emphasize the key role that computer simulations can play in interpreting vSFG spectra and revealing microscopic details of water at complex interfaces, which can be difficult to extract from experiments due to the mixing of second-order, surface-sensitive and third-order, bulk-dependent contributions to the vSFG response.

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

Panicle, spikelet, and floret development in orchardgrass (Dactylis glomerata)

1993 ◽  
Vol 71 (4) ◽  
pp. 523-532 ◽  
Author(s):  
Joanna Fraser ◽  
Eric G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Unique Feature ◽  
Dactylis Glomerata ◽  
Bilateral Symmetry ◽  
Second Order ◽  
Third Order ◽  
First Order ◽  
Lateral Branches ◽  
Scanning Electron

The initial stages of panicle, spikelet, and floret development in field-grown 'Kay' orchardgrass were examined using scanning electron microscopy. Spikelets arose from a complex multilevelled sequence of initiation from branch apices. Spikelets developed indirectly in a two-tiered progression: (i) an acropetal and basipetal sequence of first order, second-order, and third-order inflorescence apices, and (ii) an acropetal development within subclusters of higher-order lateral branch inflorescence apices. The panicle had the unique feature of dorsiventrality as well as bilateral symmetry. The basal apex from first-order, second-order, or third-order apices developed on the same side of the main axis as the first-order apex. The two glumes subtending each spikelet primordium developed alternately and acropetally. Development and initiation of florets within spikelets was basipetal within the panicle, basipetal within clusters and subclusters of spikelets on lateral branches, and acropetal within spikelets. Within florets, paleas developed later than lemmas. Key words: Dactylis glomerata, cocksfoot, scanning electron microscopy, development, panicle.

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

scholarly journals Probing the Locally Generated Even and Odd Order Nonlinearity in Y–Ba–Cu–O and Tl–Ba–Ca–Cu–O (2212) Microwave Resonators Around <img src="/images/tex/19586.gif" alt="T_{\rm C}">

2013 ◽  
Vol 23 (3) ◽  
pp. 9000105-9000105 ◽  
Author(s):  
Brooke Jeries ◽  
Sean Cratty ◽  
S Remillard
Keyword(s):  
Meissner Effect ◽  
Second Order ◽  
Intermodulation Distortion ◽  
Coaxial Cable ◽  
Superconducting Resonators ◽  
Third Order ◽  
Odd Order ◽  
Similar Temperature Dependence ◽  
Similar Temperature ◽  
Lower Temperature

Spatial scanning of the synchronously generated second- and third-order intermodulation distortion in superconducting resonators uncovers local nonlinearity hot spots, and possible time reversal symmetry breaking, using a simple probe fashioned from coaxial cable. It is clear that even and odd order nonlinearity in these samples do not share the same physical origins, because their temperature and static magnetic field dependences are quite different. 2nd order intermodulation distortion remains strong in these measurements as the temperature continues to drop belowTCto 77 K even though the 3rd order peaks nearTCand becomes smaller at lower temperature as predicted by the nonlinear Meissner effect. Both YBa2Cu3O7and Tl2Ba2CaCu2O8resonators of the same structure exhibit similar temperature dependence in the second order with second order remaining high at lower temperature. The YBa2Cu3O7sample has lower third-order intermodulation distortion with a pronounced peak atTC.

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