Strong Excitation Research Articles

Social Media Emotions and IPO Returns

AbstractI explore how investor emotions on StockTwits and Twitter affect initial public offering (IPO) returns. High pre‐IPO enthusiasm is linked to greater initial returns but eventual long‐term underperformance. IPOs with strong early excitement average a 29.73% initial return, but suffer a −8.22% long‐term industry‐adjusted return, showing a gap between early optimism and later results. Analysis of investor communication reveals that financial language and existing information influence these outcomes. There is a growing caution among frequent IPO investors, likely due to past experiences. Despite this, firms with initial high optimism continue to attract postlaunch interest, contradicting their long‐term underperformance.

Seismic collapse performance assessment of high‐strength steel framed‐tube structures with shear links fabricated using low‐yield‐point steel

SummaryA high‐strength steel framed‐tube structure with shear links fabricated using low‐yield‐point steel (HSSFTS‐LYPSL) was developed in this study to improve the seismic performance and resilience of the conventional steel framed‐tube structure. When this HSSFTS‐LYPSL is subjected to strong earthquake excitation, its shear links undergo significant plastic deformation to dissipate seismic energy while critical components such as the spandrel beams and columns maintain their elasticity. Furthermore, the replacement of damaged links was facilitated by the use of bolted end‐plate connections. This study designed three typical HSSFTS‐LYPSL examples with 20, 30, and 40 stories to investigate the seismic collapse performances of HSSFTS‐LYPSLs at different seismic intensity levels. Three‐dimensional nonlinear finite element analysis models of these example structures were developed using the OpenSEES software, and the accuracy and effectiveness of the modeling approach was validated by comparing its results with those of quasi‐static tests on sub‐structure assemblies. Next, 40 records each of far‐field and pulse‐type near‐field ground motions were selected and applied with an incremental dynamic analysis (IDA) to obtain response curves for the example structures and calculate their collapse fragility curves and collapse margin ratios (CMRs) utilizing a modified collapse fragility model. Finally, based on the collapse fragility and seismic hazard curves, the seismic collapse risk probability curves of the HSSFTS‐LYPSLs were obtained under far‐ and near‐field earthquakes, revealing that at the maximum considered earthquake level, the CMR values ranged from 5.74 to 7.25 and from 4.85 to 6.67, respectively; at the very rare earthquake (VRE) level, the CMR values ranged from 3.83 to 4.85 and from 3.24 to 4.46, respectively. These results demonstrate that HSSFTS‐LYPSLs exhibit sufficient potential for seismic collapse resistance. As pulse‐type near‐field earthquakes had more significant and adverse impacts on the seismic collapse performances of the HSSFTS‐LYPSLs than far‐field earthquakes, the seismic collapse design of an HSSFTS‐LYPSL should particularly consider the influence of near‐field effects. In addition, the seismic hazard function had a greater effect on the structural seismic collapse risk curves than the collapse fragility function, suggesting that seismic collapse risk curves could provide a comprehensive assessment of HSSFTS‐LYPSL seismic collapse performance. Under far‐ and near‐field earthquakes, the annual collapse risk probabilities of the HSSFTS‐LYPSL examples at the VRE level were within 1.18 × 10−5–4.53 × 10−5, which is below the seismic collapse risk threshold recommended by others, indicating that HSSFTS‐LYPSLs can meet the fourth‐level performance objective of “no collapse failure at the VRE level.” However, this study only conducted seismic collapse and risk assessments using example HSSFTS‐LYPSLs; future research will focus on determining the seismic recovery capacities of and developing post‐earthquake repairability methodologies for HSSFTS‐LYPSLs.

The Influence of Soil Deformability on the Seismic Response of 3D Mixed R/C–Steel Buildings

Following effective seismic codes, common buildings are considered to be made of the same material throughout the story distribution and based on an ideal rigid soil. However, in daily construction practice, there are often cases of buildings formed by a bottom part constructed with reinforced concrete (r/c) and a higher steel part, despite this construction type not being recognized by code assumptions. In addition, soil deformability, commonly referred to as the Soil–Structure Interaction (SSI), is widely found to affect the earthquake response of typical residence structures, apart from special structures, though it is not included in the normative design procedure. This work studies the seismic response of in-height mixed 3D models, considering the effect of sustaining deformable ground compared to the common rigid soil hypothesis, which has not been clarified so far in the literature. Two types of soft soil, as well as the rigid soil assumption, acting as a reference point, are considered, while two limit interconnections between the steel part on the concrete part are included in the group analysis. The possible influence of the seismic orientation angle is explored in the analysis set. Selected numerical results of the dynamic nonlinear analyses under strong near-fault ground excitations were plotted through dimensionless parameters to facilitate an objective comparative discussion. The effect of SSI on the nonlinear performance of three-dimensional mixed models is identified, which serves as the primary contribution of this work, making it unique among the numerous research works available globally and pointing to findings that are useful for the enhancement of the seismic rules regarding the design and analysis of code-neglected mixed buildings.

Dynamics of phase transformations in Si and Ge upon strong excitation with UV femtosecond laser pulses

Femtosecond laser processing of semiconductors has evolved into a mature, high-precision fabrication technique, enabling a wide range of applications. While initially most studies have employed pulses at near infrared wavelengths, the interest in using UV laser pulses is constantly increasing due to the different excitation conditions as a consequence of the much shorter optical penetration depth, leading to an improved resolution. In this context, fundamental studies on the temporal dynamics of phase transformations triggered by such pulses are necessary in order to comprehend and eventually control the complex phase transformation pathways. Here, we report a detailed time-resolved study on the phase transformation dynamics of crystalline silicon and germanium upon irradiation with single 400 nm, 100 fs laser pulses in the moderate and high excitation regime. To this end, we have employed fs-resolved optical microscopy with a probe wavelength of 800 nm to study the reflectivity evolution of the irradiated surface over a temporal window ranging from 100 fs up to 20 ns. At moderate excitation fluence, the data reveals the entire sequence of laser-induced processes, starting from the generation of a free-electron plasma, non-thermal melting, ablation onset and expansion of a semi-transparent ablation layer with sharp interfaces. At excitation with peak fluences more than 30 times the ablation threshold, an anomalous transient high-reflectivity state is observed, which might be indicative of a recoil pressure-induced liquid–liquid phase transition. Moreover, 70 nm-thick amorphous surface layers are formed in both materials after irradiation at moderate fluences. Overall, our results provide relevant information on both, transformation dynamics and final state of both materials for fs-pulse excitation in the near-UV wavelength range.

Speed limits of the laser-induced phase transition in FeRh

We use ultrafast x-ray diffraction and the polar time-resolved magneto-optical Kerr effect to study the laser-induced metamagnetic phase transition in two FeRh films with thicknesses below and above the optical penetration depth. In the thin film, we identify an intrinsic timescale for the light-induced nucleation of ferromagnetic (FM) domains in the antiferromagnetic material of 8ps, which is substantially longer than the time it takes for strain waves to traverse the film. For the inhomogeneously excited thicker film, only the optically excited near-surface part transforms within 8ps. For strong excitations, we observe an additional slow rise of the FM phase, which we experimentally relate to a growth of the FM phase into the depth of the layer by comparing the transient magnetization in frontside and backside excitation geometry. In the lower lying parts of the film, which are only excited via near-equilibrium heat transport, the FM phase emerges significantly slower than 8ps after heating above the transition temperature.

Comparative study of the multiple wavelength lasing of nitrogen ions: the role of vibrational level-dependent photoionization

We report on an optical amplification and energy threshold of the two most prominent emission lines, 391.4 and 427.8 nm, of the cavity-less lasing of nitrogen ions pumped by femtosecond laser pulses. It was found that the two transitions both show optical amplification under a low gas pressure condition, while the 391.4 nm emission is barely amplified under high gas pressure. Moreover, the 427.8 nm emission presents a significant lower pump laser energy threshold and a larger gain factor than the 391.4 nm emission. Numerical simulations based on a three-state coupling model suggest that the smaller ionization Franck–Condon factor from the ground state of N2 to the vibrational level ν = 1 in X2Σ g + state of N2+ favors the formation of population inversion corresponding to the 427.8 nm emission. Meanwhile, the competition between the strong field ionization and excitation induced by the pumping laser requires higher laser intensity to acquire the population inversion for the 391.4 nm radiation, leading to a corresponding larger energy threshold.

Low-noise inverse magnetoelectric magnetic field sensor

In the development of any type of magnetic field sensor based on magnetic films, special consideration must be given to the magnetic layer component. The presented work investigates the use of scalable flux closing magnetostrictive multilayers for inverse magnetoelectric sensors. In such a type of magnetic field sensor, highly sensitive AC and DC field detection relies on strong excitation of the incorporated magnetic layers by piezoelectrically driven cantilever oscillation at mechanical resonances. The provoked periodic flux change is influenced by the magnetic field to be measured and is picked up by a coil, which generates the measured output. The multilayered inverse magnetoelectric sensor is investigated with regard to linearity, noise behavior, and detection limit of DC and AC signals. A significant advancement for inverse magnetoelectric thin film sensors is demonstrated in this study. Using exchange bias stabilized magnetic multilayers with flux closure structures, detection limits are improved by an order of magnitude to less than 8 pT/Hz1/2 at 10 Hz and 18 pT/Hz1/2 at DC.

Coherent Raman Scattering Spectral Shapes in a Strong Excitation Regime (Model Calculations)

Coherent Raman Scattering Spectral Shapes in a Strong Excitation Regime (Model Calculations)

Distinguishing criminal offenses committed in a state of great emotional distress from related corpus delicti of criminal offenses

The article examines the positions of scholars, as well as the provisions of current legislation and the draft Criminal Code of Ukraine in terms of distinguishing criminal offenses committed in a state of great emotional distress from related corpus delicti of criminal offenses.
 The author analyzes judicial and law enforcement practice for premeditated murder in a state of great emotional distress, by a mother of her newborn child, and in case of exceeding the limits of necessary defense or in case of exceeding the measures necessary to detain the person who committed the criminal offense.
 The author defines theoretical approaches to the qualification of acts committed in a state of great emotional distress and the position, taking into account the case law, on the distinguishing criminal offenses committed in a state of great emotional distress from related corpus delicti of criminal offenses. It is substantiated that for the correct qualification of crimes committed in a state of strong mental excitement, it is necessary to establish not only the features of the corresponding crimes, but also to distinguish them from the related corpus delicti of crimes, since the type and degree of responsibility of the person for the committed criminal offense, as well as the degree, depend on this punishment, which is imposed in case of finding a person guilty of committing a criminal offense.

Optional features of the objective side in crimes against life and health under the legislation of some countries of the Romano-Germanic legal family (using the example of Germany and France)

The need for an integrated approach to the study of optional by nature signs of the objective side and their role in crimes against life and health requires turning to the experience of foreign countries. In this connection, the work examines some features of the construction of optional signs of the objective side in the above-mentioned criminal offenses in the criminal legislation of Germany and France. The conducted comparative research made it possible to see ways of improvement and vectors of development of criminal law policy, the implementation of which is carried out precisely by the correction of the criminal law. Based on the results of the work, the author indicates that legislators in Germany and France, unlike in Russia, do not attach serious importance to optional signs of the objective side when constructing crimes against life and health. At the same time, certain features in the regulation of optional signs of the objective side in crimes against life and health, which are not characteristic of domestic law, are still refined. For example, in Germany, in relation to murder in a state of passion, not only the determinants of the occurrence of a state of strong emotional excitement, but also the pre-criminal behavior of the subject of the crime are taken into account. It is also noted that the German Criminal Code regulates liability for participation in a fight; it regulates liability for abortion that occurs outside the established period of pregnancy at which it is possible. In addition, it was revealed that the French Criminal Code criminalizes hiring to commit murder if the mercenary did not plan to commit a criminal act. In conclusion, the author of the work suggests ways to improve domestic legislation taking into account the studied foreign experience.

Laser‐Induced Real‐Space Topology Control of Spin Wave Resonances

AbstractFemtosecond laser excitation of materials exhibiting magnetic spin textures promises advanced magnetic control via the generation of non‐equilibrium spin dynamics. Ferrimagnetic [Fe(0.35 nm)/Gd(0.40 nm)]160 multilayers are used to explore this approach, as they host a rich diversity of magnetic textures from stripe domains at low magnetic fields, a dense bubble/skyrmion lattice at intermediate fields, and a single domain state for high magnetic fields. Using femtosecond magneto‐optics, distinct coherent spin wave dynamics are observed in this material in response to a weak laser excitation, enabling an unambiguous identification of the different magnetic spin textures. Moreover, employing strong laser excitation, versatile control of the coherent spin dynamics via non‐equilibrium transformation of magnetic spin textures becomes possible by both creating and annihilating bubbles/skyrmions. Micromagnetic simulations and Lorentz transmission electron microscopy with in situ optical excitation corroborate these findings.

High-repetition-rate injection-seeded terahertz-wave parametric generation pumped by a 1.5 μm sub-nanosecond laser

Injection-seeded terahertz (THz)-wave parametric generation (is-TPG) using a nonlinear optical crystal of MgO-doped lithium niobate (MgO:LiNbO3) has made it possible to obtain THz waves with high peak powers and narrow linewidths. To achieve stable THz-wave generation from the MgO:LiNbO3 crystal under strong excitation, the photorefractive effect in the MgO:LiNbO3 crystal would be crucial, which could be eliminated by using a longer pump wavelength than the conventional 1-μm spectral band. Here, we propose to use a 1.5-μm near-infrared (NIR), high-repetition-rate, sub-nanosecond laser source based on a unique Er,Yb:glass planar waveguide amplifier (PWA) as the pump source for the is-TPG using the MgO:LiNbO3 crystal. At a repetition rate of 25 kHz, the frequency tunability from 1.3 to 2.5 THz was obtained with a maximum THz-wave average output power of 0.14 mW at 1.77 THz.

Seismic isolation technology of shallow buried large section utility tunnel with soft soils in seismically vulnerable area

Shallow utility tunnels with exceptionally large cross-sections in weak soil can face significantly more severe seismic risks compared to conventional deep tunnels in seismic hazard areas. This study investigates the seismic response and isolation technologies applied to a large section utility tunnel with 4 compartments in one layer, employing seismic simulations. The engineering context, dynamic motions, and measuring points of the numerical simulation were introduced. Subsequently, the finite element method was employed to explore the seismic behaviors of the large section utility tunnel when subjected to strong earthquake excitations under four conditions. The study explored and comparatively evaluated the seismic isolation effectiveness of three proposed schemes: the grouting scheme, the buffer layer, and the assembly of three-quarters buffer layer, cushion and grouting. The analysis included various indexes such as the deformation, the principal and shear stress, and the safety factor. The finding reveals that the assembly seismic scheme exhibits the most significant seismic effect (95.39%), followed by the buffer layer (38.82%), and the grouting scheme (25.66%). The assembly seismic scheme is recommended for the seismic design in the current large-section utility tunnels. These conclusions provide valuable scientific guidance for the seismic design of large-section utility tunnels, aiding in enhancing earthquake resilience.

Analysis of the optimal target node to reduce seizure-like discharge in networks

Network approaches have been widely accepted to guide surgical strategy and predict outcome for epilepsy treatment. This study starts with a single oscillator to explore brain activity, using a phenomenological model capable of describing healthy and epileptic states. The ictal number of seizures decreases or remains unchanged with increasing the speed of oscillator excitability and in each seizure, there is an increasing tendency for ictal duration with respect to the speed. The underlying reason is that the strong excitability speed is conducive to reduce transition behaviors between two attractor basins. Moreover, the selection of the optimal removal node is estimated by an indicator proposed in this study. Results show that when the indicator is less than the threshold, removing the driving node is more possible to reduce seizures significantly, while the indicator exceeds the threshold, the epileptic node could be the removal one. Furthermore, the driving node is such a potential target that stimulating it is obviously effective in suppressing seizure-like activity compared to other nodes, and the propensity of seizures can be reduced 60% with the increased stimulus strength. Our results could provide new therapeutic ideas for epilepsy surgery and neuromodulation.

Excitation and ionization of OCS molecules in strong UV and NIR laser fields

Abstract Rydberg state excitation (RSE) is a highly non-linear physical phenomenon that is induced by the ionization of atoms or molecules in strong femtosecond laser fields. Here we observe that both parent and fragments (S, C, OC) of the tri-atomic molecule carbonyl sulfide (OCS) can survive strong 800 nm or 400 nm laser fields in high Rydberg states. The dependence of parent and fragment RSE yields on laser intensity and ellipticity is investigated in both laser fields, and the results are compared with those for strong-field ionization. Distinctly different tendencies for laser intensity and ellipticity are observed for fragment RSE compared with the corresponding ions. The mechanisms of RSE and strong-field ionization of OCS molecules in different laser fields are discussed based on the experimental results. Our study sheds some light on the strong-field excitation and ionization of molecules irradiated by femtosecond NIR and UV laser fields.

Theoretical and experimental study of a bi-stable piezoelectric energy harvester under hybrid galloping and band-limited random excitations

In the practical environment, it is very common for the simultaneous occurrence of base excitation and crosswind. Scavenging the combined energy of vibration and wind with a single energy harvesting structure is fascinating. For this purpose, the effects of the wind speed and random excitation level are investigated with the stochastic averaging method (SAM) based on the energy envelope. The results of the analytical prediction are verified with the Monte-Carlo method (MCM). The numerical simulation shows that the introduction of wind can reduce the critical excitation level for triggering an inter-well jump and make a bi-stable energy harvester (BEH) realize the performance enhancement for a weak base excitation. However, as the strength of the wind increases to a particular level, the influence of the random base excitation on the dynamic responses is weakened, and the system exhibits a periodic galloping response. A comparison between a BEH and a linear energy harvester (LEH) indicates that the BEH demonstrates inferior performance for high-speed wind. Relevant experiments are conducted to investigate the validity of the theoretical prediction and numerical simulation. The experimental findings also show that strong random excitation is favorable for the BEH in the range of low wind speeds. However, as the speed of the incoming wind is up to a particular level, the disadvantage of the BEH becomes clear and evident.

Hovering Flight of a Robotic Hummingbird: Dynamic Observer and Flight Tests

The paper reports on flight tests at hovering of the COLIBRI robot. After a short review of the control model and the stabilization strategy, two different approaches are considered for the attitude reconstruction from the MEMS Inertial Measurement Unit (IMU): the complementary filter and the full-state dynamic observer, implemented in a specially designed flight control board. It is shown that both strategies provide adequate stabilization at hovering in spite of the strong vibration excitation resulting from the flapping of the wings. Moreover, it is shown that the residual wandering due to noise, robot imperfection, etc., can be significantly reduced by a cascade control loop based on the axial and lateral velocities reconstructed by the full-state observer. Experiments show that this approach based on onboard measurements allows for a station keeping as good as that obtained with velocities reconstructed from an external tracking system. The paper also reports endurance tests conducted with two different robot configurations; the maximum flight time observed is 4 min 30 s.

Tesla-class single-cycle terahertz magnetic field pulses generated with a spiral-shaped metal microstructure

Abstract We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with near-infrared light. The determined magnetic field strength and field-enhancement spectrum are consistent with the theoretical predictions. This first report of the detection of the magnetic field of a Tesla-class picosecond pulse by magneto-optical sampling is expected to be useful in research on the control of magnetization in spintronic devices.

Separation of Oral Cooling and Warming Requires TRPM8.

Cooling sensations arise inside the mouth during ingestive and homeostasis behaviors. Oral presence of cooling temperature engages the cold and menthol receptor TRPM8 (transient receptor potential melastatin 8) on trigeminal afferents. Yet, how TRPM8 influences brain and behavioral responses to oral temperature is undefined. Here we used in vivo neurophysiology to record action potentials stimulated by cooling and warming of oral tissues from trigeminal nucleus caudalis neurons in female and male wild-type and TRPM8 gene deficient mice. Using these lines, we also measured orobehavioral licking responses to cool and warm water in a novel, temperature-controlled fluid choice test. Capture of antidromic electrophysiological responses to thalamic stimulation identified that wild-type central trigeminal neurons showed diverse responses to oral cooling. Some neurons displayed relatively strong excitation to cold <10°C (COLD neurons) while others responded to only a segment of mild cool temperatures below 30°C (COOL neurons). Notably, TRPM8 deficient mice retained COLD-type but lacked COOL cells. This deficit impaired population responses to mild cooling temperatures below 30°C and allowed warmth-like (≥35°C) neural activity to pervade the normally innocuous cool temperature range, predicting TRPM8 deficient mice would show anomalously similar orobehavioral responses to warm and cool temperatures. Accordingly, TRPM8 deficient mice avoided both warm (35°C) and mild cool (≤30°C) water and sought colder temperatures in fluid licking tests, whereas control mice avoided warm but were indifferent to mild cool and colder water. Results imply TRPM8 input separates cool from warm temperature sensing and suggest other thermoreceptors also participate in oral cooling sensation.

Ultrafast hot-carrier dynamics in ultrathin monocrystalline gold

Applications in photodetection, photochemistry, and active metamaterials and metasurfaces require fundamental understanding of ultrafast nonthermal and thermal electron processes in metallic nanosystems. Significant progress has been recently achieved in synthesis and investigation of low-loss monocrystalline gold, opening up opportunities for its use in ultrathin nanophotonic architectures. Here, we reveal fundamental differences in hot-electron thermalisation dynamics between monocrystalline and polycrystalline ultrathin (down to 10 nm thickness) gold films. Comparison of weak and strong excitation regimes showcases a counterintuitive unique interplay between thermalised and non-thermalised electron dynamics in mesoscopic gold with the important influence of the X-point interband transitions on the intraband electron relaxation. We also experimentally demonstrate the effect of hot-electron transfer into a substrate and the substrate thermal properties on electron-electron and electron-phonon scattering in ultrathin films. The hot-electron injection efficiency from monocrystalline gold into TiO2, approaching 9% is measured, close to the theoretical limit. These experimental and modelling results reveal the important role of crystallinity and interfaces on the microscopic electronic processes important in numerous applications.