Возможность управления динамикой и структурой магнитного солитона в трехслойной ферромагнитной структуре

The generation and excitation of a magnetic soliton in a three-layer ferromagnet by constant magnetic fields and fields of variable frequency and small amplitude in the presence of dissipation in the system are considered. The analysis of the solutions of the equation of motion in an alternating field shows the possibility of increasing the amplitude of the magnetic soliton over time under certain conditions. The resonant effect is also affected by the geometric parameters of the thin layer: at a large layer width, the translational mode of the soliton oscillations is also excited.

Computational and Spectroscopic Studies of Carbon Disulfide

The vibrational spectroscopy of CS2 has been investigated many times in all three phases. However, there is still some ambiguity about the location of two of the modes in the solid state. The aim of this work was to locate all of the modes by inelastic neutron scattering (INS) spectroscopy, (which has no selection rules), and to use periodic density functional theory to provide a complete and unambiguous assignment of all the modes in the solid state. A comparison of the observed and calculated INS spectra shows generally good agreement. All four of the ν2 bending mode components are calculated to fall within 14 cm−1. Inspection of the spectrum shows that there are no bands close to the intense feature at 390 cm−1 (assigned to ν2); this very strongly indicates that the Au mode is within the envelope of the 390 cm−1 band. Based on a simulation of the band shape of the 390 cm−1 feature, the most likely position of the optically forbidden component of the ν2 bending mode is 393 ± 2 cm−1. The calculations show that the optically inactive Au translational mode is strongly dispersed, so it does not result in a single feature in the INS spectrum.

The effect of impurities on striped phases

We study the effect of algebraically localized impurities on striped phases in one spatial dimension. We therefore develop a functional-analytic framework that allows us to cast the perturbation problem as a regular Fredholm problem despite the presence of the essential spectrum, caused by the soft translational mode. Our results establish the selection of jumps in wavenumber and phase, depending on the location of the impurity and the average wavenumber in the system. We also show that, for select locations, the jump in the wavenumber vanishes.

Sky-Birds & Dead Trees On Two Images in Edmond Jabès

Chapter 2 concerns two recurrent images from Edmond Jabès’s late works, Un étranger avec, sous le bras, un livre de petit format (1989) and Le livre de l’hospitalité (1991). While Jabès is well known within French literary circles, analyses of his early Cairene work— and to an even lesser extent the formative roles of orality and aurality from his pre- Parisian period—are few and thin. I first contextualize the figure of the Egyptian poet in relation to the history of Jabès scholarship, and then build on Tengour’s translational poetics of the classical Arabic literary archive in order to unravel a different, sublimated translational mode that links many of Jabès’s later books. In his late and final works, which he composed while living in Paris, Jabès’s poetic imaginary reprises word for word the tropes of early Arabic verse. When read together and in relation to the same archival corpus, Tengour and Jabès represent contrasting translational and intertextual modes for comparative poetic and translingual compositions in French. Through his aphasic refuge in French monolingualism following his exile from Cairo, and his late re/discovery of classical Arabic poetry in Paris, Jabès’s sublimated recourse to early Arabic verse retraces and performs the history of the old literary forms beneath a French language surface.

Medical Research by the Medical Colleges in India

ABSTRACT Background: Research conducted in medical colleges in India is often considered to be of poor quality. The study was done to assess the cause for such occurrence. Materials and Methods: Papers published in indexed journals between 1985 to 2017 were reviewed and the data was synthesized. Results: Poor infrastructure, heavy patient load, restricted number of faculties who had limited exposure to research methodologies, private practice, lack of incentive to do good quality research, poor mentoring, lack of research tradition, research fund, ancillary infrastructures, and copy cat research were found to be some of the reasons. Discussions and Solutions: Teachers education, provision of better infrastructure and funding, short term fellowships at both undergraduate and postgraduate levels, proper assessment for promotion of teachers, training in research methodology, multicentric research, R & D research bases in medical colleges, looking for solutions for day-to-day challenges through operational and translational mode are some of the solutions. Training from undergraduate levels on elements of research needed to be encouraged.

Transient birefringence of liquids induced by terahertz electric-field torque on permanent molecular dipoles

Collective low-frequency molecular motions have large impact on chemical reactions and structural relaxation in liquids. So far, these modes have mostly been accessed indirectly by off-resonant optical pulses. Here, we provide evidence that intense terahertz (THz) pulses can resonantly excite reorientational-librational modes of aprotic and strongly polar liquids through coupling to the permanent molecular dipole moments. We observe a significantly enhanced response because the transient optical birefringence is up to an order of magnitude higher than obtained with optical excitation. Frequency-dependent measurements and a simple analytical model indicate that the enhancement arises from resonantly driven librations and their coupling to reorientational motion, assisted by the pump field and/or a cage translational mode. Our results open up the path to applications such as efficient molecular alignment, enhanced transient Kerr signals and systematic resonant nonlinear THz spectroscopy of the coupling between intermolecular modes in liquids.

Three-Dimensional Modeling and Structured Vibration Modes of Two-Stage Helical Planetary Gears Used in Cranes

The dynamic investigation of helical planetary gears plays an important role in structure design as the vibration and noise are perceived negatively to the transmission quality. With consideration of the axial deformations of members, the gyroscopic effects, the time-variant meshing stiffness, and the coupling amongst stages, a three-dimensional dynamic model of the two-stage helical planetary gears is established by using of the lumped-parameter method in this paper. The model is applicable to variant number of planets in two stages, different planet phasing, and spacing configurations. Numerical simulation is conducted to detect the structured vibration modes of the equally spaced systems. Furthermore, the unique properties of these vibration modes are mathematically proved. Results show that the vibration modes of the two-stage helical planetary gears can be categorized as five classes: the rigid body mode, the axial translational-rotational mode, the radical translational mode, and the 1st-stage and the 2nd-stage planet mode.

Interactions enhance the acoustic streaming around flattened microfluidic bubbles

The vibration of bubbles can produce intense microstreaming when excited by ultrasound near resonance. In order to study freely oscillating bubbles in steady conditions, we have confined bubbles between the two walls of a silicone microchannel and anchored them on micropits. We were thus able to analyse the microstreaming flow generated around an isolated bubble or a pair of interacting bubbles. In the case of an isolated bubble, a short-range microstreaming occurs in the channel gap, with additional in-plane vortices at high amplitude when Faraday waves are excited on the bubble periphery. For a pair of bubbles, we have observed long-range microstreaming and large recirculations describing a ‘butterfly’ pattern. We propose a model based on secondary acoustic Bjerknes forces mediated by Rayleigh waves on the silicone walls. These forces lead to attraction or repulsion of bubbles and thus to the excitation of a translational mode in addition to the breathing mode of the bubble. The mixed-mode streaming induced by the interaction of these two modes is shown to generate fountain or anti-fountain vortex pairs, depending on the relative distance between the bubbles.