Ordinary Resonance Research Articles

Diagnosis and treatment of hidden lesions in "mild" cervical spondylotic myelopathy patients with apparent symptoms.

Patients with apparent symptoms of cervical spondylotic myelopathy (CSM) may only show a mild compressive lesion in ordinary magnetic resonance imaging (MRI). The aim of this study was to investigate the characteristics of CSM patients with “hidden” lesions on kinetic MRI and to determine an effective treatment.Thirty-one patients with obvious spinal cord compression only on kinetic MRI were included in our study. A variety of parameters were calculated from MRI of the cervical spine at different postures. The anterior cervical decompression and fusion (ACDF) procedure were used for treatment of CSM. To evaluate the effect of surgery, a further 31 age- and gender-matched ordinary CSM patients that received ACDF procedures were enrolled as the control group.The diameter of the cervical cord at the narrowest level in extension was significantly lower than that in the neutral posture (P < .01). The percentage of spinal cord compression was 34.6%. The diameter of the cervical canal at the narrowest level in the extension posture was significantly lower than that in the neutral posture (P < .01). The percentage of cervical canal stenosis was 43.6%. The anteroposterior diameter of the cervical canal in the case group was significantly lower than that in the control group (P < .01). However, the recovery rate of the Japanese Orthopaedic Association score at final follow-up was comparable between the case group and the control group (P = .53).Kinetic MRI is useful for the diagnosis of CSM with hidden lesions. ACDF is an effective procedure for treatment of CSM.

The non-ordinary Regge behavior of the K^*_0(800) or kappa -meson versus the ordinary K^*_0(1430)

The Regge trajectory of an elastic resonance can be calculated from dispersion theory, instead of fitted phenomenologically, using only its pole parameters as input. This also provides a correct treatment of resonance widths in Regge trajectories, essential for very wide resonances. In this work we first calculate the K^*_0(1430) Regge trajectory, finding the ordinary almost real and linear behavior, typical of q bar{q} resonances. In contrast, for the K^*_0(800) meson, the resulting Regge trajectory is non-linear and has a much smaller slope than ordinary resonances, being remarkably similar to that of the f_0(500) or sigma meson. The slope of these unusual Regge trajectories seems to scale with the meson masses rather than with scales typical of quark degrees of freedom. We also calculate the range of the interaction responsible for the formation of these resonances. Our results strongly support a non-ordinary, predominantly meson–meson-like, interpretation for the lightest strange and non-strange resonances.

The influence of higher spatial harmonics of atomic polarization on the saturated absorption resonance upon excitation of open dipole transitions by a field of counterpropagating waves

The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with an atomic gas is studied. The experimental observation of this effect was first reported in 2011 in a work by our colleagues at the P.N. Lebedev Physical Institute of the Russian Academy of Sciences (Laboratory of Frequency Standards). The essence of the effect lies in the fact that, on exciting an open dipole transition, another, narrower, resonance of an opposite sign can be observed at the center of the ordinary saturated absorption resonance. A theoretical analysis of this effect has also been performed in this work in terms of a simple spectroscopic model of an atom with two nondegenerate energy levels without taking into account higher spatial harmonics of atomic polarization and polarizations of light waves (scalar model). The present work is devoted to the development of a theory of the formation of a central narrow resonance for the example of a real Fg = 1 → Fe = 1 atomic transition and to the study of its main characteristics (amplitude, width, contrast, and amplitude-to-width ratio). In addition, the theoretical results obtained without taking into account the influence of higher spatial harmonics and with inclusion of the influence of first higher harmonics are compared. This comparison shows that their influence on the parameters of the new nonlinear resonance is strong even in moderately intense light fields (R ~ γ, where R is the Rabi frequency). The results of this study can be of interest for quantum metrology, as well as for many experiments in which the laser-radiation frequency is stabilized by the saturated absorption resonance on open dipole transitions in atoms and molecules.

High-Q Fano-like resonance based on a symmetric dimer structure and its terahertz sensing application

High quality factor (Q) Fano-like resonance with intense electromagnetic confinement is essential for ultrasensitive refractive index label-free sensors. Ordinarily, planar metamaterials with asymmetric configurations are the main approaches to demonstrate these extremely narrow line-width Fano-like resonances. In this work we present a high-Q Fano-like resonance with a symmetric structure consisting of a bilayer split-ring resonator (SRR) dimer structure with identical SRR array on each layer. We find that the interference between the resonances arising from the top and bottom layers of SRR array could also give rise to Fano-like resonance with more than twenty times enhanced Q -factor (Q = 19.28) comparing to that of a single layer SRR array (Q = 0.8). The figure of merit of this Fano-like resonance (FOM = 1.79) is about ten times larger than that of the ordinary electric dipole resonance (FOM = 0.186) when applied to terahertz sensing. Our symmetric structure opens up a new way to realize the high Q Fano-like resonances, which would facilitate the design of ultrasensitive chemical and biomolecular sensing platform at terahertz frequency.

Exploiting the principle parametric resonance of an electric oscillator for vibratory energy harvesting

Vibratory energy harvesters typically exploit ordinary direct resonances to mechanically amplify environmental inputs before channeling a portion of their energy into an electric load using an electromechanical transduction mechanism. Nonetheless, parametric resonance which has also been recently exploited, but to a lesser extent, holds a key advantage over direct excitations in that, when the level of input excitation exceeds a certain threshold, the amplitude of growth associated with parametric pumping is not limited by the total linear damping present in the system. While all of the previous research studies using parametric resonances for energy harvesting focused on utilizing it as a means of mechanical amplification, this letter demonstrates that vibratory excitations can also be used effectively to induce parametric resonances in the harvesting circuit itself, thereby providing a direct and simple means of electric amplification. A vibratory energy harvester exploiting this phenomenon is proposed in this letter and is shown to produce a maximum of 18 mW root-mean-square power per 1 g of input acceleration.

Monochromatic Tuning of Absorption Strength Based on Angle-Dependent Closed-Ring Resonator-Type Metamaterial Absorber

In this study, almost monochromatic tuning of absorption strength, i.e., tuning the absorption peak level at almost the same frequency, is presented by using an angle-dependent closed-ring resonator (AD-CRR)-type narrowband absorber structure in S -band. With this aim, first an ordinary planar closed-ring resonator (CRR) structure having a ground plane is designed, and then the structure is folded inward by a rotation angle α from $\alpha = 0^{^\circ }$ (i.e., a planar CRR) to $\alpha = 60^{^\circ }$ along the center line, which is parallel to the incident electric field. Both simulation and experimental results agree with the fact that the rotation angle α provides the freedom of tuning the absorption strength of the absorber structure almost monochromatically.

Low dispersion broadband integrated double-slot microring resonators optical buffer

Microring resonator optical buffer is attractive in high-speed optical network system, but ordinary microring resonator use strip waveguide as its basic light guide medium, which cannot provide small footprint, low dispersion and high delay-bandwidth product (DBP) simultaneously. Double-slot waveguide structure was first proposed to construct racetrack-microring resonators. It was found that cascading multiple microrings can increase the delay-bandwidth and lower the dispersion of the resonators by optimizing the structure parameters. Optical buffer cascaded by 8 microrings with flat bandwidth of 20 GHz provided the delay of 150 ps and the dispersion of ~10–7 ps/nm over 1530–1630 nm, and the footprint of each microring was about 51μm2. This study can provide design methods and theoretical basis support for practical application.

Broadband resonant cavity inside a two-dimensional sonic crystal

A rectangular cavity inside a two-dimensional sonic crystal was theoretically and experimentally characterized by examining its response to a cylindrical source emitting narrow-band filtered noise bursts with central frequencies ranging from 2 to 12kHz. A broadband intensity resonance was observed for frequencies within the full band-gap region of the sonic crystal (5.5–6.5kHz). Unlike ordinary resonances, this broadband resonance depends on the reflection properties of the sonic crystal forming the surrounding walls rather than on the geometry of the cavity.

Coupled-mode approach to square-gradient Bragg-reflection resonances in corrugated dielectric waveguides

We demonstrate the appearance of unexpected reflection resonances in corrugated dielectric waveguides. These are due to the curvature of the boundary. The effect is as strong as the ordinary Bragg resonances, and reduces the transmission through our waveguide by 20%. It is thus of high relevance for the design of optimized waveguiding structures. We validate our analytical predictions based on coupled-mode theory by a comparison to numerical simulations.

Strong reflection and periodic resonant transmission of helical edge states in topological-insulator stub-like resonators

The helical edge states of two-dimensional topological insulators (TIs) experience appreciable quantum mechanical scattering in narrow channels when the width changes abruptly. The interference of the geometry scattering in narrow-wide-narrow waveguide structures is shown to give rise to the strong suppression of transmission when the incident energy is barely above the propagation threshold. Periodic resonant transmission takes place in this high reflection regime while the length of the wide section is varied. The resonance condition is governed by the transverse confinement in the wide section, where the form of quantization is manifested to differ for the two orthogonal directions. The confined energy levels in TI quantum dots are derived based on this observation. In addition, the off-diagonal spin-orbit term is found to produce an anomalous resonance state, which merges with the bottom ordinary resonance state to annihilate.

A perforated microring resonator for optical sensing applications

In this paper, we present numerical simulations of a refractive index sensor based on a perforated optical microring resonator. We show that the introduction of subwavelength perforations in the microring resonator increases the light–matter interaction and the sensitivity of the microring resonator. Here, the sensor performance is analyzed in two sensing schemes: bulk sensing and dielectric particle sensing. In both applications the perforated microring resonator sensor outperforms an ordinary microring resonator sensor and also maintains a high quality factor. The simulations were performed using finite-difference time domain and finite-element methods.

Air-band optical resonators in one-dimensional Si photonic crystal waveguides for biosensing applications

Optical cavities using air-band states in Si photonic crystals (PhCs) are proposed as biosensors. Since the light in the air band of PhCs is preferably located at the lower-index cladding rather than the inside of higher-index Si, interactions are enhanced between the light and the target molecules in the cladding, being effective for the sensitive detections. Such an air-band PhC is used as an optical cavity, which is surrounded with another PhC as the photonic-bandgap mirrors. Simulations are performed for air-band resonators in one-dimensional (1D) PhC of arrayed holes in a Si channel waveguide, in order to analyze a figure of sensing, i.e., red shifts in the resonance wavelengths induced by the presence of target molecules. The S value, the amount of red shift caused by the unit change in the cladding index, can be as large as 200 nm/RIU, which is 2 times larger than those for ordinary 1D-PhC resonators. Fabricated devices successfully show the resonance peaks, whose wavelengths and quality factors agree well with theoretical ones. These results suggest that the air-band resonators are promising for high-performance biosensors.

Observation of a new type of magnetic excitations in NdFe3(BO3)4 ferroborate

AFMR spectra of single crystal NdFe3(BO3)4 are studied over frequencies of 15–32.2 GHz and temperatures of 2.17–10 K in fields H &amp;lt; Hsf. The presence of an incommensurate magnetic structure in these parameter ranges is found to lead to significant changes in the resonance properties of the system. The frequencies of the ordinary resonance remain finite up to the spin-flop transition field Hsf and an additional branch of excitations with unusual hysteresis properties appears. The frequency-field and frequency-temperature dependences for this branch are determined within the above ranges of these parameters.

Impulse and Resonant Response in Systems Showing Secular and Leaky Excitations

A model consisting of a string embedded in an elastic medium and terminated by a harmonic oscillator has been studied in the frequency and time domains to elucidate the physical e ects of supersonic and subsonic leaky waves as well as that of true surface waves. A supersonic leaky wave manifests itself by a resonant maximum of the local density of states within the band of bulk waves and by an anomalous dispersion of the real part of the frequency dependent response function. The time domain impulse response then contains mainly resonant contribution from the poles of the response function in analogy to ordinary resonances. True surface waves show generally analogous behaviour. Here, however, the phenomenon is governed by dissipation mechanisms di erent from the radiation into the bulk. An important di erence is that the impulse response contains equilibrated contributions due to the poles and due to the stop frequency gap in the case of true surface waves. The main manifestation of a subsonic leaky wave, i.e. a surface resonance with the frequency situated in the stop gap, is a sharp peak of the real part of the frequency-dependent response function just at the bottom of the bulk waves band. This is in certain analogy with a large reactive power in electric circuits. A strong destructive interference of the resonant part of the impulse response with the part due to the gap makes the time domain response fast attenuated.

Multistability and Torus Reconstruction in a DC–DC Converter With Multilevel Control

By virtue of their limited size and relatively low costs, multilevel dc-dc converters have come to play an important role in modern industrial power supply systems. When operating in a regime of high corrector gain, such converters can display a variety of new dynamic phenomena associated with the appearance of additional oscillatory modes. Starting in a state where four pairs of stable and unstable period-6 cycles coexist with the basic period-1 cycle, the paper describes a sequence of smooth and nonsmooth bifurcations through which the cycles and their basins of attraction transform as the output voltage is increased. The paper also describes the birth of a multilayered resonance torus through a transverse pitchfork bifurcation of the saddle cycle on an ordinary resonance torus.

Midlatitude propagation of VLF to MF waves through nighttime ionosphere above powerful VLF transmitters

AbstractMidlatitude nighttime observations made by the DEMETER satellite in the very low frequency (VLF) to medium frequency (MF) bands (3 kHz to 3 MHz) have demonstrated the propagation of radio waves from the bottom of ionosphere up to the satellite altitude (~700 km). Propagation characteristics derived from the magneto‐ionic theory [Budden, ] are used to explain the absence of wave observations between ~1 and 2 MHz. Under hypotheses made for the Appleton and Hartree (or Appleton and Lassen) formula, studies of the vertical variations of the real and imaginary parts of the refractive index are performed to point out modifications in the propagation characteristics of the waves: (i) at the crossing of the plasma cutoffs regions, (ii) at the crossing of the ordinary and extraordinary mode resonance regions, and (iii) in the region where the product of the collision frequency (ν) and the electronic density (Ne) is maximum. It is shown that enhancements in the collision frequencies, produced by powerful VLF transmitters in the region where the product of ν and Ne is maximum, open the half angle of the MF wave transmission cones and increase the power densities of those waves at the DEMETER altitude.

Through-bond instability in polyphenol tautomers

Unusual instability of keto tautomers in polyphenols is theoretically analyzed. Apart from ordinary resonance energy and bond energy, it is shown that there should be additional keto instability originated from through-bond interactions between the true and pseudo π orbitals. The interactions are characteristic of non-bonding like amplitude pattern in the frontier π orbitals. The magnitude of instability is estimated to be 4kcal/mol per carbonyl group by modern DFT calculations and experimental results.

Semiconductor laser with a birefringent external cavity for information systems with wavelength division multiplexing

The spectrum of a semiconductor laser with a birefringent external Gires–Tournois cavity is studied. The generation of two main laser modes corresponding to the ordinary and extraordinary wave resonances is found. It is shown that the radiation spectrum is controlled with a high energy efficiency without losses for spectral filtration. The possibility of using two-mode lasing in optical communication systems with wavelength division multiplexing is shown.

A study of resonance structures with different frequency scales in the spectrum of background extremely low-frequency noise at middle latitudes

Using the data of continuous monitoring of low-frequency background noise at the station “Novaya Zhizn” (Nizhny Novgorod Province, Russia) for 2006–2010, we studied a new spectral structure appearing in quasi-harmonic oscillations of the noise intensity with frequency scales a factor of 3 to 4 smaller than the scales of an ordinary spectral resonance structure. The features of the fine spectral structure were studied, i.e., frequency of occurrence, diurnal dynamics, and the frequency bandwidth. The features of an ordinary resonance structure were also studied in the “fine structure” appearance and the transition solar-activity periods (2010–2011). Using the calculations of the low-frequency magnetic fields propagating in a spherically horizontally inhomogeneous Earth–ionosphere waveguide, we analyzed the possible influence of the nonlocal ionospheric properties on the magnetic-component spectra in the range 0.1–20 Hz. It is shown that the influence of the nonlocal ionospheric properties on the extremely low-frequency spectra can be observed in the presence of an ionospheric horizontal inhomogeneity due to different shapes of the ionospheric-parameter profiles along the radio-wave propagation path.

An improved criterion for Kapitza's pendulum stability

An enhanced and more exact criterion for dynamic stabilization of the parametrically driven inverted pendulum is obtained: the boundaries of stability are determined with greater precision and are valid in a wider region of the system parameters than previous results. The lower boundary of stability is associated with the phenomenon of subharmonic resonances in this system. The relationship of the upper limit of dynamic stabilization of the inverted pendulum with ordinary parametric resonance (i.e. with destabilization of the lower equilibrium position) is established. Computer simulation of the physical system aids the analytical investigation and proves the theoretical results.