Double Resonance Effect Research Articles

Particle-in-cell simulations of electron–positron cyclotron maser forming pulsar radio zebras

Context. The microwave radio dynamic spectra of the Crab pulsar interpulse contain fine structures represented via narrowband quasiharmonic stripes. The pattern significantly constrains any potential emission mechanism. Similar to the zebra patterns observed, for example, in type IV solar radio bursts or decameter and kilometer Jupiter radio emission, the double plasma resonance (DPR) effect of the cyclotron maser instability may allow for interpretion of observations of pulsar radio zebras. Aims. We provide insight at kinetic microscales of the zebra structures in pulsar radio emissions originating close to or beyond the light cylinder. Methods. We present electromagnetic relativistic particle-in-cell (PIC) simulations of the electron–positron cyclotron maser for cyclotron frequency smaller than the plasma frequency. In four distinct simulation cycles, we focused on the effects of varying the plasma parameters on the instability growth rate and saturation energy. The physical parameters were the ratio between the plasma and cyclotron frequency, the density ratio of the “hot” loss-cone to the “cold” background plasma, the loss-cone characteristic velocity, and comparison with electron–proton plasma. Results. In contrast to the results obtained from electron–proton plasma simulations (for example, in solar system plasmas), we find that the pulsar electron–positron maser instability does not generate distinguishable X and Z modes. On the contrary, a singular electromagnetic XZ mode was generated in all studied configurations close to or above the plasma frequency. The highest instability growth rates were obtained for the simulations with integer plasma-to-cyclotron frequency ratios. The instability is most efficient for plasma with characteristic loss-cone velocity in the range vth = 0.2 − 0.3c. For low density ratios, the highest peak of the XZ mode is at double the frequency of the highest peak of the Bernstein modes, indicating that the radio emission is produced by a coalescence of two Bernstein modes with the same frequency and opposite wave numbers. Our estimate of the radiative flux generated from the simulation is up to ∼30 mJy from an area of 100 km2 for an observer at 1 kpc distance without the inclusion of relativistic beaming effects, which may account for multiple orders of magnitude.

Polarization dependence of intensities Raman peaks in twisted graphene bilayer

The polarization dependence of the Raman 2D peak intensity and the polarization independence of the G Raman peak intensity have already been established in single-layer and AB-stacked bilayer graphene. Nevertheless, this study has not been conducted for twisted bilayers. In this study, we investigate the polarization properties of Raman peaks in three distinct twisted bilayer graphene samples, each exhibiting unique characteristics: G peak resonance, the presence of R′ peaks, and D-like peaks, respectively. Our analysis reveals anisotropic behavior in the G peak only under resonance enhancement conditions and consistent polarization-dependent behavior in the 2D peak across all twisted bilayers. Furthermore, we observe a pronounced symmetric and asymmetric polarization dependence in the intensity of R′ and D-like peaks, respectively. These observations have been attributed to the strong coupling between the two layers resulting from the resonance between the van Hove singularities, which affects the behavior of the G peak, and to a double resonance effect that enhances the coupling between the nodal structure and the electron–phonon anisotropy in the intravalley and intervalley regions for R′ and D-like peaks, respectively. These findings contribute to the advancement of our understanding of twisted bilayer systems and offer opportunities for exploring more profound studies.

Double resonance between corner states in distinct higher-order topological phases

Recent studies have shown that higher-order topologies in photonic systems lead to a robust enhancement of light–matter interactions. Moreover, higher-order topological phases have been extended to systems even without a band gap, as in Dirac semimetals. In this work, we propose a procedure to simultaneously generate two distinctive higher-order topological phases with corner states that allow a double resonant effect. This double resonance effect between the higher-order topological phases, was obtained from the design of a photonic structure with the ability to generate a higher-order topological (HOTI) insulator phase in the first bands and a higher-order Dirac half-metal phase (HODSM). Subsequently, using the corner states in both topological phases, we tuned the frequencies of both corner states such that they were separated in frequency by a second harmonic. This idea allowed us to obtain a double resonance effect with ultra-high overlap factors, and a considerable improvement in the nonlinear conversion efficiency. These results show the possibility of producing a second-harmonic generation with unprecedented conversion efficiencies in topological systems with simultaneous HOTI and HODSM phases. Furthermore, since the corner state in the HODSM phase presents an algebraic 1/r decay, our topological system can be helpful in experiments about the generation of nonlinear Dirac-ligh–matter interactions.

Insights on the role of local site effects on damage distribution in the Izmir metropolitan area induced by the October 30, 2020 Samos earthquake

On the 30th of October 2020, a 6.6 magnitude earthquake occurred 14 km north of Samos Island, causing 119 casualties (117 in Izmir, Türkiye, and 2 in Samos, Greece) and significant damage in the 3rd biggest city of Türkiye, Izmir. Although the city is roughly 70 km far away from the epicenter, the damage was significant and concentrated in the city center settled on alluviums. This paper aims to analyze the distribution of damage in Izmir province, by crosschecking the recorded motions, the subsoil conditions and the evidence of damage as collected by an ad-hoc on-site reconnaissance. The intrinsic behavior of the Samos earthquake was investigated by employing three different ground-motion prediction equations. The results of the analyses revealed that site effects play a significant role in the amplification of ground motions, and valley effects are responsible for the concentration of damage. The damage in buildings was classified in terms of the intensity and structural typologies for the 30 districts of Izmir metropolitan area. In-depth analysis of the distribution of damages revealed that the earthquake caused damage all over the boundaries of Izmir province, and the concentration of damage in Bornova and Karşıyaka districts has a clear correlation with double resonance effects.

Double resonant tunable second harmonic generation in two-dimensional layered materials through band nesting

We proposed a mechanism to generate giant anisotropic second harmonic nonlinear response via double resonance effect, achieved through band nesting via electronic band-structure engineering. The ideal band setup would be a triplet of nested bands separated by the fundamental resonance energy $\ensuremath{\hbar}\ensuremath{\omega}$. We demonstrate theoretically that the proposed phenomenon can be realized in bilayer SnS by band tuning with perpendicular electrical bias, which maximizes the second harmonic susceptibility by several orders of magnitude. Moreover, the tunability of the polarization anisotropy can be useful for realizing novel polarization-sensitive devices.

Soil-building resonance effect in the urban area of Villa d’Agri (Southern Italy)

This study aims to evaluate the possible occurrence during seismic shaking of interaction effects between the shallow subsoil and the overlying buildings of the Villa d’Agri town (Southern Italy). From the geological and building heritage points of view, the investigated area represents a typical town along the Apennines chain and therefore the obtained results could be easily exported to similar urban areas. A total of 239 single-station seismic ambient noise measurements were thus performed, 154 on the urban soils and 85 within buildings. Both subsets of measurements were planned to cover the main outcropping lithologies and building typologies. By means of the Horizontal-to-Vertical Noise Spectral Ratio technique, isofrequency and isoamplitude maps have been reconstructed for the whole area. The results evaluated on the 65 tested buildings allowed to infer the empirical relationship between the first vibrational period, T(s), and their height, H(m). Using this relationship and available information on the height of each building, the first vibrational frequency was estimated for 659 buildings belonging to the urban area of Villa d'Agri. Finally, in order to assess the possible occurrence of the double resonance phenomenon, we compared the main frequency of each building with that interpolated for the underlying foundation soil. The results show that the probability of being affected by the double resonance effect is very high only for a couple of buildings, high for about 16% of the buildings, moderate for the 23% and practically null for most buildings (60%).

Assisted ultrasonic wave of vanillin derivatives synthesis and antioxidant activity using DPPH method

In recent years, the need for compounds with antioxidant activities have expanded. Generally, the natures of these compounds involve the presence of conjugated double bonds, phenolic groups, and resonance effects on the structure. One of the compounds with the phenolic group is vanillin. It can be modified into the derivative of 1,8-dioxo-octahydroxantene compound due to its aldehyde content. Meanwhile, 1,8-dioxo-octahydroxantene compound has two 2- cyclohexenone rings bound in the pyran ring and one phenolic group, expected to carry more excellent antioxidant activity than vanillin. The 9-(4-hydroxy-3-methoxyphenyl)-3,4,5,6,7,9- hexahydro -1H-xantene-1,8(2H)-dione (Compound 1) was synthesized from 1,3- cyclohexanedione and vanillin through Knoevenagel's condensation reaction aided with an acid catalyst with a single reaction phase. Besides, green chemistry was adopted in this study using environmentally friendly catalysts from lime juice and ultrasonic wave. The synthesized compounds' structure was confirmed through the spectrophotometer IR, GC-MS, and 1H-NMR spectrometer, while its antioxidant activity was tested using the DPPH method. The reaction occurred with and without lime juice catalyst, producing yields of 6.65% and 70.58%, respectively. The results of the antioxidant activity test suggest that Compound 1 carries substantially robust antioxidant activities, with IC50 of 0.99 ppm.

Analysis of the robustness and dynamics of spin-locking preparations for the detection of oscillatory magnetic fields

Extracting quantitative information of neuronal signals by non-invasive imaging is an outstanding challenge for understanding brain function and pathology. However, state-of-the-art techniques offer low sensitivity to deep electrical sources. Stimulus induced rotary saturation is a recently proposed magnetic resonance imaging sequence that detects oscillatory magnetic fields using a spin-lock preparation. Phantom experiments and simulations proved its efficiency and sensitivity, but the susceptibility of the method to field inhomogeneities is still not well understood. In this study, we simulated and analyzed the dynamic of three spin-lock preparations and their response to field inhomogeneities in the presence of a resonant oscillating field. We show that the composite spin-lock preparation is more robust against field variations within the double resonance effect. In addition, we tested the capability of the chosen composite spin-lock preparation to recover information about the spectral components of a composite signal. This study sets the bases to move one step further towards the clinical application of MR-based neuronal current imaging.

Double stochastic energetic resonance of underdamped two-scale bistable system

Multistable structures have abundant nonlinear characteristics, a multi-level system with large-scale and small-scale bistable structures is constructed, and its dynamic characteristic is discussed. Based on the complete Langevin equation with an inertial term and a variable damping term, the relationship between the Kramers escape rate and the damping coefficient is deduced and the approximate analytical expression of the output response in the underdamped state is established. From the view of the energy, the mechanism of double resonance and resonance effect enhancement induced by damping is further revealed with the energy dissipation caused by damping as the core. The physical quantity work is introduced to measure the strength of the resonance effect. The results of theoretical analysis and numerical simulation indicate that as the damping coefficient decreases into the underdamping or even the weak damping scope, the double stochastic resonance phenomenon induced by noise still exists. The strongest resonance effect can be obtained with the optimal damping value.

Photonic crystal meso-cavity with double resonance for second-harmonic generation

In this work, we study a composite zinc oxide photonic crystal (PhC) that includes a meso-cavity coupled to a PhC L3 microcavity to obtain a double resonance effect and second-harmonic generation (SHG) conversion efficiency as high as 468 W−1. This exceptional conversion efficiency was attributed to the high quality-factors Q found in the fundamental and second-harmonic (SH) modes whose values were of the order of 105 and 106, respectively. Since the L3 microcavity plays a relevant role in the SHG of the composite PhC, we performed a calculation of its photonic band structure to observe the induced modes in its bandgap. Furthermore, we also found that the resonant mode adjusted to the frequency of the SH exhibits high Purcell factors of the order of 105. Hence, in a semiconductor material, it can be easily enhanced the light emission at the SH frequency using an adequate driving fundamental frequency light beam. These results can stimulate the engineering of photonic nanostructures in semiconductor materials to achieve highly efficient non-linear effects with applications in cavity quantum electrodynamics.

Double Fano resonance based on Fabry-Perot mode and asymmetric waveguide mode

Fano resonance effect has potential applications in many nanophotonics devices, Such as switch, sensor, and modulators. To realize double Fano resonance effect, in this paper, we present a novel coupling mechanism in a multi-layer metamaterial structure. The structure consists of periodic TiO2 grating covered with MgF2-TiO2-Ag multilayer with a MgF2 substrate. Results show that one of the two Fano resonance is caused by the interference between a broad Fabry-Perot (FP) mode and a dark waveguide mode (WG), and the other Fano resonance is caused by the asymmetric waveguide mode of the MgF2-TiO2-Ag layer. The effect of structural parameters on transmission is also studied, the field distribution of the proposed nanostructure is presented to illustrate the mechanism. We achieve a refractive index sensitivity of 73.5 nm/RIU, and temperature sensitivity of 0.0915nm/°C, the ultra-narrow transmission bandwidth leads to the high FOM*. The results will pave the way towards the design of double band Fano resonance, which may have potential application in high signal-to-noise ratio measurement, plasmonic modulator and refractive index sensor or temperature sensor.

Vibrational resonance in a neuron-astrocyte coupled model.

Recent findings have revealed that not only neurons but also astrocytes, a special type of glial cells, are major players of neuronal information processing. It is now widely accepted that they contribute to the regulation of their microenvironment by cross-talking with neurons via gliotransmitters. In this context, we here study the phenomenon of vibrational resonance in neurons by considering their interaction with astrocytes. Our analysis of a neuron-astrocyte pair reveals that intracellular dynamics of astrocytes can induce a double vibrational resonance effect in the weak signal detection performance of a neuron, exhibiting two distinct wells centred at different high-frequency driving amplitudes. We also identify the underlying mechanism of this behaviour, showing that the interaction of widely separated time scales of neurons, astrocytes and driving signals is the key factor for the emergence and control of double vibrational resonance. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 2)'.

PIC Simulation of Double Plasma Resonance and Zebra Pattern of Solar Radio Bursts

Abstract The latest study has reported that plasma emission can be generated by energetic electrons of Dory–Guest–Harris distribution via the electron cyclotron maser instability (ECMI) in plasmas characterized by a large ratio of plasma oscillation frequency to electron gyro-frequency (ω pe /Ω ce ). In our study, on the basis of the ECMI-plasma emission mechanism, we examine the double plasma resonance (DPR) effect and the corresponding plasma emission at both harmonic (H) and fundamental (F) bands using particle-in-cell simulations with various ω pe /Ω ce . This allows us to directly simulate the feature of the zebra pattern (ZP) observed in solar radio bursts for the first time. We find that (1) the simulations reproduce the DPR effect nicely for the upper hybrid and Z modes, as seen from their variation of intensity and linear growth rate with ω pe /Ω ce , (2) the intensity of the H emission is stronger than that of the F emission by ∼2 orders of magnitude and varies periodically with increasing ω pe /Ω ce , while the F emission is too weak to be significant (therefore, we suggest that it is the H emission accounting for solar ZPs), (3) the peak-valley contrast of the total intensity of H is ∼4, and the peak lies around integer values of ω pe /Ω ce (=10 and 11) for the present parameter setup. We also evaluate the effect of energy of energetic electrons on the characteristics of ECMI-excited waves and plasma radiation. The study provides novel insight on the physical origin of ZPs of solar radio bursts.

Ag/γ-AgI/Bi2O2CO3/Bi S-scheme heterojunction with enhanced photocatalyst performance

The metal defect engineering is the crux to accomplish the goal of local electronic regulation, which is an important factor for visible light to drive photocatalyst performance. In this paper, the solvothermal-precipitation method was used to reduce Bi in situ via the reducer glucose to construct Ag-AgI/Bi-Bi2O2CO3-OVs heterojunction. The Ag-AgI/Bi-Bi2O2CO3-OVs composite photocatalyst has excellent photoresponse ability and fast charge carrier separation. In addition, the powerful S-scheme heterojunction retains the original redox capability of the components. The unique lawn-like structure exhibits favorable surface scattering and reflection, which promotes efficient separation of photoinduced charge carriers. Especially, 30% Ag-AgI/Bi-Bi2O2CO3-OVs exhibits brilliant photocatalytic performance for the degradation of tetracycline, which is 4.85 times and 1.15 times higher than the original Bi2O2CO3 and AgI, respectively. The enhanced photocatalytic activity mainly attributes to the presence of oxygen vacancies, the sensitization of Ag-AgI, the double surface plasmon resonance (SPR) effect, and the heterogeneous interface due to the improved morphology, which effectively inhibits the recombination of electron-hole pairs. This work provides a new perspective for the reasonable construction and simple synthesis of high-performance Bi-based semiconductor photocatalysts.

Origin of the zebra structure in the Jovian decameter radio emission

Context.We discuss the origin of quasi-harmonic emission bands that have been observed in the dynamic spectra of the Jovian decameter emission.Aims.We aim to show that the interpretation of the observed structure can be based on the effect of double plasma resonance (DPR) at ion cyclotron harmonics.Methods.According to the proposed model, in the extended source in the upper ionosphere of Jupiter, where the DPR condition is satisfied for one of the ion cyclotron frequency harmonics, the ion cyclotron waves are effectively excited at the frequency of the lower hybrid resonance. The observed electromagnetic radiation with a quasi-harmonic structure arises due to scattering of ion cyclotron waves by supra-thermal electrons.Results.Based on the VIP4 magnetic field model, we determine the longitudes at which the source of the considered radiation can be located. The obtained estimates of the plasma density and its height distribution in the source, as well as the energies of emitting ions and scattering electrons provide information about the plasma parameters in the upper ionosphere of Jupiter. Furthermore, these estimates are in good agreement with the observational data.

Origin of quasi-harmonic emission bands with fine structure in the dynamic spectra of high-frequency interpulses of the Crab pulsar

ABSTRACT We study the origin of quasi-harmonic emission bands with fine structure observed in the dynamic radiation spectra of high-frequency interpulses. The possible explanation of observed structure is based on the effect of double plasma resonance (DPR) at electron cyclotron harmonics realized in the magnetosphere of pulsar in a local radio emission source filled with non-relativistic plasma. The model of the source consists of neutral current sheet with a transverse magnetic field where plasma waves are generated due to DPR effect. It is shown that the emergence of emission bands and their frequency spacing are due to the inhomogeneity of the plasma and magnetic field along the current sheet, and their fine structure is due to the inhomogeneity of the current sheet in the direction orthogonal to it. Each quasi-harmonic emission band represents a system of elements of fine features of radiation that is generated by suprathermal electrons under DPR conditions. The observed upward drift of quasi-harmonic emission bands is due to the displacement of suprathermal electrons across the current sheet and an increase in the DPR frequencies with distance from the central plane of the layer.

Evaluation of soil-building resonance effect in the urban area of the city of Matera (Italy)

This study discusses the effect of buildings vibrations in the urban field in the context of local seismic response studies in order to evaluate the possible occurrence of double resonance effects during strong-motions. The aim is to recognise the interaction effect between near surface geology and all overlying buildings in the urban area of the city of Matera (southern Italy). Single station seismic ambient noise measurements (230) were performed on the main lythologies (134) and on the principal building typologies (96). Soil and building measurements allowed estimating the main frequencies and relative amplitudes of the soil fundamental peaks as well as the first vibrational frequency of buildings. The period-height linear relationship, derived by experimental results, made it possible estimating the fundamental frequency for all the Matera's buildings. Having also estimated the frequencies at each point of the urban soil it was thus possible to obtain a soil-building resonance map in the linear elastic domain. Matera represents an important case study because the first vibration frequency for most of the buildings is quite close to those of the foundation soils. About 21% of buildings show high probability of occurrence of soil-building resonance effect, about 63% of the buildings are characterised by a medium resonance level, while about 16% are at zero or very low level. The proposed approach makes it also possible to identify the areas of the city characterised by these different probabilities of resonance levels.

Review: recent progress in metal-less metasurfaces and metamaterials

Plasmonic metamaterials (MMs) are based on light coupling to metal free electrons, which inherently accompanied with severe dissipation losses that usually limit device performance. Furthermore, the complexity in designing 3D plasmonic MMs have left them far beyond from being realized in the real market for on-chip nanophotonic applications. Dielectric MMs have alternatively served as an ultimate solution to tackle the low efficiency problem of metal-based MMs. In this review paper, we present optically thin dielectric-based metasurfaces (DMs) that allow for phase and polarization manipulation of light. DMs are essentially based on excitation of double Mie resonance effect, which inherits DMs the ability to modulate light with 2π phase modulation, thus, serving in variety of applications including metalens, beam steering, holograms and optical chirality. Two main classes of DMs are mainly covered which are: Huygens’s metaurfaces and Geometric phase metasurfaces. We first introduce the underlying physics of DMs and propose applications that have been realized with high efficiencies. In the second part, we demonstrate another class of MMs which is semiconductor based hyperbolic metamaterial (HMM). Semiconductor based HMM has two main advantages which are: their ease of fabrication in analogy with DMs and their ability to operate in the mid IR range. We outline HMMs’ applications including thermal harvesting, focusing and mid IR absorption. Finally, we overview the current challenges and future goals for the field of dielectric MMs in order to be realized for real market application.

Site effects in Mexico City basin: Past and present

Due to the unique subsoil conditions prevailing in the Mexico City basin, seismic risk has been strongly correlated to site effects. Thus, during the Mw 8.1 09/19/1985 subduction fault earthquake, and its strong aftershock Mw 7.5 09/21/1985, extensive damage was observed in the area, along with the loss of thousands of lives, despite these events had an epicentral distance of around 430 km from Mexico City. The observed damage was mostly due to site affects originated by the high plastiCity clay deposits found in the basin, which lead to large amplifications, and duration elongation of the ground motions coming from the epicenter. In addition, a frequency content modification occurs, which in turn, leads to a double resonance effect between the incoming ground motions, soil deposits, and the damaged buildings. Exactly 32 years after this devastating event, the Mw 7.1 09/19/2017 normal fault earthquake, reminded us of the importance of accounting for site effects, and most importantly the need to carry out a proper characterization of basin geometry, soil profile configuration, hydraulic conditions, and maintenance-structure periodic assessments of the building stock in Mexico City. This is required to reduce uncertainties of seismic vulnerability studies for extreme-event seismic hazard scenarios. In this paper, the role of site response and seismic soil-structure interaction as key factors responsible of the observed damage in the City is revisited, through series of 3D finite difference models of typical structure-foundation-soil typologies found at the areas where most of the damage was observed, highlighting its clear impact in the final damage distribution observed around the City.

CP violation induced by the double resonance for pure annihilation decay process in perturbative QCD

In a perturbative QCD approach we study the direct CP violation in the pure annihilation decay process of bar{B}^0_{s}rightarrow pi ^+pi ^-pi ^+pi ^- induced by the rho and omega double resonance effect. Generally, the CP violation is small in the pure annihilation type decay process. However, we find that the CP violation can be enhanced by double rho –omega interference when the invariant masses of the pi ^+pi ^- pairs are in the vicinity of the omega resonance. For the decay process of bar{B}^0_{s}rightarrow pi ^+pi ^-pi ^+pi ^-, the CP violation can reach A_{CP}(bar{B}^0_{s}rightarrow pi ^+pi ^-pi ^+pi ^-)=27.20^{+0.05+0.28+7.13}_{-0.15-0.31-6.11}%.