The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the ...The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean.However,an overlooked fact by previous studies is that the loosely defined“TIWs”actually consist of two modes,including the Yanai wave-based TIW on the equator(hereafter eTIW)and the Rossby wave-based TIW off the equator(hereafter vTIW).Hence,the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored.In this study,individual coupling relationships are established for both eTIW and v TIW,including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations,and the relationship between the TIW-induced wind stress perturbation divergence(curl)and the downwind(crosswind)TIW-induced SST gradients.Results show that,due to different distributions of eTIW and vTIW,the coupling strength induced by the eTIW is stronger on the equator,and that by the vTIW is stronger off the equator.The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs.We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models.However,the coupling relationships cannot be well represented in most numerical models.Finally,we confirmed that higher resolution usually corresponds to more accurate simulation.Therefore,the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.展开更多
Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of poros...Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics simulations.Firstly,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental data.The pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock wave.The microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete compaction.Finally,it leads to stress relaxation and velocity homogenization.The shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of density.Besides,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the system.The energy is dissipated mainly through the multiple interactions of the waves under shock.The energy is dissipated mainly by the friction between atoms under non-shock.展开更多
Landslide-generated impulsive waves(LGWs)in reservoir areas can seriously threaten waterway safety as well as hu-man life and properties around the two side slopes.The risk reduction and mitigation of such a hazard re...Landslide-generated impulsive waves(LGWs)in reservoir areas can seriously threaten waterway safety as well as hu-man life and properties around the two side slopes.The risk reduction and mitigation of such a hazard require the accurate prediction of near-field wave characteristics,such as wave amplitude and run-up.However,near-field LGW involves complicated fluid-solid interactions.Furthermore,the wave characteristics are closely related to various aspects,including the geometry and physical features of the slide,river,and body of water.However,the empirical or analytical methods used for rough estimation cannot derive accurate results,especially for deformable landslides,due to their significant geometry changes during the sliding process.In this study,the near-field waves generated by deformable landslides were simulated by smoothed particle hydrodynamics(SPH)based on multi-phase flow.The deformable landslides were generalized as a kind of viscous flow by adopting the Herschel-Bulkley-Papanastasiou(HBP)-based nonNewtonian rheology model.The HBP model is capable of producing deformable landslide dynamics even though the high-speed sliding process is involved.In this study,an idealized experiment case originating from Lituya LGW and a practical case of Gongjiafang LGW were reproduced for verification and demonstration.The simulation results of both cases show satisfactory consistency with the experiment/investigation data in terms of landslide movement and near-field impulsive wave characteristics,thus indicating the applicability and accuracy of the proposed method.Finally,the effects of the HBP model’s rheological parameters on the landslide dynamics and near-field wave characteristics are discussed,providing a parameter calibration method along with sug-gestions for further applications.展开更多
Magnetosonic waves are an important medium for energy transfer in collisionless space plasma.Magnetosonic waves have been widely investigated in the upstream of the bow shock at Mars.These waves are believed to origin...Magnetosonic waves are an important medium for energy transfer in collisionless space plasma.Magnetosonic waves have been widely investigated in the upstream of the bow shock at Mars.These waves are believed to originate from pickup ions or reflected particles.By utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail region.These plasma waves are associated with a significant enhancement of proton and oxygen flux.The excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma escape.Our results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere.展开更多
Neuron-astrocyte interactions are vital for the brain’s connectome.Understanding astrocyte activities is crucial for comprehending the complex neural network,particularly the population-level functions of neurons in ...Neuron-astrocyte interactions are vital for the brain’s connectome.Understanding astrocyte activities is crucial for comprehending the complex neural network,particularly the population-level functions of neurons in different cortical states and associated behaviors in mammals.Studies on animal sleep and wakefulness have revealed distinct cortical synchrony patterns between neurons.Astrocytes,outnumbering neurons by nearly fivefold,support and regulate neuronal and synaptic function.Recent research on astrocyte activation during cortical state transitions has emphasized the influence of norepinephrine as a neurotransmitter and calcium waves as key components of ion channel signaling.This summary focuses on a few recent studies investigating astrocyte-neuron interactions in mouse models during sleep,wakefulness,and arousal levels,exploring the involvement of noradrenaline signaling,ion channels,and glutamatergic signaling in different cortical states.These findings highlight the significant impact of astrocytes on large-scale neuronal networks,influencing brain activity and responsiveness.Targeting astrocytic signaling pathways shows promise for treating sleep disorders and arousal dysregulation.More research is needed to understand astrocytic calcium signaling in different brain regions and its implications for dysregulated brain states,requiring future human studies to comprehensively investigate neuron-astrocyte interactions and pave the way for therapeutic interventions in sleep-and arousal-related disorders.展开更多
The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distributio...The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented.In the domain of kinetic model,the twisted IA waves are characterized by Laguerre-Gaussian(LG) solutions,where plasma distribution function and electric field are decomposed into axial and azimuthal components.The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures.The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.展开更多
The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent ...The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent initial value, which would permit in certain models classical coherent initial gravitational wave states. Furthermore, several arguments pro and con as to if or not initial relic GW should be high frequency will be presented, with the reason given why earlier string models did NOT favor low frequency relic GW from the big bang. What is observed is that large higher dimensions above our 4 Dimensional space time, if recipients of matter-energy from collapse and re birth of the universe are enough to insure low relic GW. The existence of higher dimensions, in itself if the additional dimensions are small and compact will have no capacity to lower the frequency limit values of relic GW, as predicted by Giovannini, et al. in 1995.展开更多
As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport significantly.Hence,it is of significance to describe the characteris...As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport significantly.Hence,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary layer.In this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary layer.Then,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel function.Consequently,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable transformation.The analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.展开更多
This study aims to investigate characteristics of continental shelf wave(CSW)on the northwestern continental shelf of the South China Sea(SCS)induced by winter storms in 2021.Mooring and cruise observations,tidal gaug...This study aims to investigate characteristics of continental shelf wave(CSW)on the northwestern continental shelf of the South China Sea(SCS)induced by winter storms in 2021.Mooring and cruise observations,tidal gauge data at stations Hong Kong,Zhapo and Qinglan and sea surface wind data from January 1 to February 28,2021 are used to examine the relationship between along-shelf wind and sea level fluctuation.Two events of CSWs driven by the along-shelf sea surface wind are detected from wavelet spectra of tidal gauge data.The signals are triply peaked at periods of 56 h,94 h and 180 h,propagating along the coast with phase speed ranging from 6.9 m/s to18.9 m/s.The dispersion relation shows their property of the Kelvin mode of CSW.We develop a simple method to estimate amplitude of sea surface fluctuation by along-shelf wind.The results are comparable with the observation data,suggesting it is effective.The mode 2 CSWs fits very well with the mooring current velocity data.The results from rare current help to understand wave-current interaction in the northwestern SCS.展开更多
The recently observed gravitational wave background is explained in terms of the quantum modification of the general relativity (Qmoger). Some UFO, FRB and supernova flares also can be explained in terms of Qmoger.
Optical remote sensing has been widely used to study internal solitary waves(ISWs).Wind speed has an important effect on ISW imaging of optical remote sensing.The light and dark bands of ISWs cannot be observed by opt...Optical remote sensing has been widely used to study internal solitary waves(ISWs).Wind speed has an important effect on ISW imaging of optical remote sensing.The light and dark bands of ISWs cannot be observed by optical remote sensing when the wind is too strong.The relationship between the characteristics of ISWs bands in optical remote sensing images and the wind speed is still unclear.The influence of wind speeds on the characteristics of the ISWs bands is investigated based on the physical simulation experiments with the wind speeds of 1.6,3.1,3.5,3.8,and 3.9 m/s.The experimental results show that when the wind speed is 3.9 m/s,the ISWs bands cannot be observed in optical remote sensing images with the stratification of h_(1)∶h_(2)=7∶58,ρ_(1)∶ρ_(2)=1∶1.04.When the wind speeds are 3.1,3.5,and 3.8 m/s,which is lower than 3.9 m/s,the ISWs bands can be obtained in the simulated optical remote sensing image.The location of the band’s dark and light extremum and the band’s peak-to-peak spacing are almost not affected by wind speed.More-significant wind speeds can cause a greater gray difference of the light-dark bands.This provided a scientific basis for further understanding of ISW optical remote sensing imaging.展开更多
The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the...The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.展开更多
We derive the potential energy of gravity waves(GWs)in the upper troposphere and stratosphere at 45°S-45°N from December 2019 to November 2022 by using temperature profiles retrieved from the Constellation O...We derive the potential energy of gravity waves(GWs)in the upper troposphere and stratosphere at 45°S-45°N from December 2019 to November 2022 by using temperature profiles retrieved from the Constellation Observing System for Meteorology,Ionosphere,and Climate-2(COSMIC-2)satellite.Owing to the dense sampling of COSMIC-2,in addition to the strong peaks of gravity wave potential energy(GWPE)above the Andes and Tibetan Plateau,we found weak peaks above the Rocky,Atlas,Caucasus,and Tianshan Mountains.The land-sea contrast is responsible for the longitudinal variations of the GWPE in the lower and upper stratosphere.At 40°N/S,the peaks were mainly above the topographic regions during the winter.At 20°N/S,the peaks were a slight distance away from the topographic regions and might be the combined effect of nontopographic GWs and mountain waves.Near the Equator,the peaks were mainly above the regions with the lowest sea level altitude and may have resulted from convection.Our results indicate that even above the local regions with lower sea level altitudes compared with the Andes and Tibetan Plateau,the GWPE also exhibits fine structures in geographic distributions.We found that dissipation layers above the tropopause jet provide the body force to generate secondary waves in the upper stratosphere,especially during the winter months of each hemisphere and at latitudes of greater than 20°N/S.展开更多
Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms an...Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.展开更多
A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the m...A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the magnetosheaths of the Earth and other planets in the solar system,yet the understanding of mirror mode waves on extraterrestrial planets is not as comprehensive as that on the Earth.Using magnetic field data collected by the Cassini spacecraft,we found peak and dip types according to the magnetic morphology(i.e.,structures with higher or lower magnetic strengths than the background field).Moreover,mirror mode waves and electromagnetic ion cyclotron waves were found one after the other,implying that the two wave modes may evolve into one another in the Kronian magnetosheath.The results indicate that many fundamental plasma processes associated with the mirror mode structure exist in the Kronian magnetosheath.The energy conversion in Saturn’s magnetosheath may provide key insights that will aid in understanding giant planetary magnetospheric processes.展开更多
There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are fe...There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are few studies on the distribution characteristics of plateau explosion shock waves,and there is still a lack of complete analysis and evaluation methods.This paper compares and analyzes shock wave overpressure data at different altitudes,obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude.The data analysis results show that at the same TNT equivalent and the same distance from the measuring point,the shock wave overpressure at high altitude is lower than that at low altitude.With the increase in the explosion center distance of the measuring point,the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes,and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance.The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%.Therefore,this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.展开更多
The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundam...The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.展开更多
It is essential to assess the evolution of soil fabric as it has an important role in the mechanical responses of soils during complex loading conditions.This contribution carries out the physical experiments using th...It is essential to assess the evolution of soil fabric as it has an important role in the mechanical responses of soils during complex loading conditions.This contribution carries out the physical experiments using three granular materials in the laboratory.The variations of compression and shear wave velocities(Vp and Vs)are investigated during load-unload cycles under dry and drained conditions.Supplementary discrete element method(DEM)simulations are performed to understand the evolution of soil fabric during the equivalent load-unload cycles using spherical particles.Vp and Vs are not always reversible even though the stress state regains its isotropic condition after unload,indicating that Vp and Vs are governed by not only the stress state but also the fabric change.The variations of Vp/Vs are density-and stress-dependent;a higher level of stress ratio(s01/s03)threshold is observed for denser packings to trigger a significant change in wave velocity ratio(Vp/Vs)for experimental results using spherical glass beads and simulation data using spherical particles.Considering the particle shape,a higher s01/s03 threshold is found for more angular particles than rounded particles.The DEM result reveals that Vp/Vs of spherical particles can be correlated linearly with the evolution of fabric ratio(Fver/Fhor)during loadunload in a pre-peak range under dry and drained conditions.展开更多
This article presents the generation of Orbital AngularMomentum(OAM)vortex waves with mode 1 using Uniform Circular Array(UCA)antenna.Two different designs,namely,UCA-1(4-element array antenna)and UCA-2(8-element arra...This article presents the generation of Orbital AngularMomentum(OAM)vortex waves with mode 1 using Uniform Circular Array(UCA)antenna.Two different designs,namely,UCA-1(4-element array antenna)and UCA-2(8-element array antenna),were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz(5G mid-band).The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique.The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value.The generated OAM waves were confirmed by measuring the null in the bore sight of their 2D radiation patterns,simulated phase distribution and intensity distribution.The measurement results agree well with the simulation results.Moreover,a detailed mode purity analysis of the generated OAM waves was carried out considering different factors.The investigation found that the greater the number of elements,the higher the purity of the generated OAM wave.Compared with other previous works,the proposed antenna design of this paper is very simple to design and fabricate.In addition,the proposed antennas are compact in design even at lower frequency band with very wide bandwidth to meet the requirements of 5G mid-band applications.展开更多
基金Supported by the National Natural Science Foundation of China(No.41976012)the Key Research Program of Laoshan Laboratory(LSL)(No.LSKJ 202202502)the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(No.XDB 42000000)。
文摘The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean.However,an overlooked fact by previous studies is that the loosely defined“TIWs”actually consist of two modes,including the Yanai wave-based TIW on the equator(hereafter eTIW)and the Rossby wave-based TIW off the equator(hereafter vTIW).Hence,the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored.In this study,individual coupling relationships are established for both eTIW and v TIW,including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations,and the relationship between the TIW-induced wind stress perturbation divergence(curl)and the downwind(crosswind)TIW-induced SST gradients.Results show that,due to different distributions of eTIW and vTIW,the coupling strength induced by the eTIW is stronger on the equator,and that by the vTIW is stronger off the equator.The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs.We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models.However,the coupling relationships cannot be well represented in most numerical models.Finally,we confirmed that higher resolution usually corresponds to more accurate simulation.Therefore,the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.
基金financial support from National Natural Science Foundation of China(Grant No.12172325)。
文摘Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics simulations.Firstly,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental data.The pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock wave.The microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete compaction.Finally,it leads to stress relaxation and velocity homogenization.The shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of density.Besides,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the system.The energy is dissipated mainly through the multiple interactions of the waves under shock.The energy is dissipated mainly by the friction between atoms under non-shock.
基金support from the National Natural Sciences Foundation of China(Nos.42177159,42077277,41877253)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUG2106304).
文摘Landslide-generated impulsive waves(LGWs)in reservoir areas can seriously threaten waterway safety as well as hu-man life and properties around the two side slopes.The risk reduction and mitigation of such a hazard require the accurate prediction of near-field wave characteristics,such as wave amplitude and run-up.However,near-field LGW involves complicated fluid-solid interactions.Furthermore,the wave characteristics are closely related to various aspects,including the geometry and physical features of the slide,river,and body of water.However,the empirical or analytical methods used for rough estimation cannot derive accurate results,especially for deformable landslides,due to their significant geometry changes during the sliding process.In this study,the near-field waves generated by deformable landslides were simulated by smoothed particle hydrodynamics(SPH)based on multi-phase flow.The deformable landslides were generalized as a kind of viscous flow by adopting the Herschel-Bulkley-Papanastasiou(HBP)-based nonNewtonian rheology model.The HBP model is capable of producing deformable landslide dynamics even though the high-speed sliding process is involved.In this study,an idealized experiment case originating from Lituya LGW and a practical case of Gongjiafang LGW were reproduced for verification and demonstration.The simulation results of both cases show satisfactory consistency with the experiment/investigation data in terms of landslide movement and near-field impulsive wave characteristics,thus indicating the applicability and accuracy of the proposed method.Finally,the effects of the HBP model’s rheological parameters on the landslide dynamics and near-field wave characteristics are discussed,providing a parameter calibration method along with sug-gestions for further applications.
基金the National Natural Science Foundation of China(42030101,42204158)Shanghai Pujiang Program(No.21PJD078)+1 种基金Shanghai Science and Technology Innovation Action Plan(No.21DZ1206100)the Fundamental Research Funds for the Central Universities.
文摘Magnetosonic waves are an important medium for energy transfer in collisionless space plasma.Magnetosonic waves have been widely investigated in the upstream of the bow shock at Mars.These waves are believed to originate from pickup ions or reflected particles.By utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail region.These plasma waves are associated with a significant enhancement of proton and oxygen flux.The excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma escape.Our results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere.
基金supported by the Corbett Estate Fund(62285-531021-41800,to EW)the Helen Vosburg McCrillus Plummer and Robert Edward Lee Plummer,Jr.Chair Fund(to JHH).
文摘Neuron-astrocyte interactions are vital for the brain’s connectome.Understanding astrocyte activities is crucial for comprehending the complex neural network,particularly the population-level functions of neurons in different cortical states and associated behaviors in mammals.Studies on animal sleep and wakefulness have revealed distinct cortical synchrony patterns between neurons.Astrocytes,outnumbering neurons by nearly fivefold,support and regulate neuronal and synaptic function.Recent research on astrocyte activation during cortical state transitions has emphasized the influence of norepinephrine as a neurotransmitter and calcium waves as key components of ion channel signaling.This summary focuses on a few recent studies investigating astrocyte-neuron interactions in mouse models during sleep,wakefulness,and arousal levels,exploring the involvement of noradrenaline signaling,ion channels,and glutamatergic signaling in different cortical states.These findings highlight the significant impact of astrocytes on large-scale neuronal networks,influencing brain activity and responsiveness.Targeting astrocytic signaling pathways shows promise for treating sleep disorders and arousal dysregulation.More research is needed to understand astrocytic calcium signaling in different brain regions and its implications for dysregulated brain states,requiring future human studies to comprehensively investigate neuron-astrocyte interactions and pave the way for therapeutic interventions in sleep-and arousal-related disorders.
文摘The ion-acoustic(IA) mode exhibiting various orbital angular momentum(OAM) states is examined in a plasma with drifting electrons.The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented.In the domain of kinetic model,the twisted IA waves are characterized by Laguerre-Gaussian(LG) solutions,where plasma distribution function and electric field are decomposed into axial and azimuthal components.The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures.The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.
文摘The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent initial value, which would permit in certain models classical coherent initial gravitational wave states. Furthermore, several arguments pro and con as to if or not initial relic GW should be high frequency will be presented, with the reason given why earlier string models did NOT favor low frequency relic GW from the big bang. What is observed is that large higher dimensions above our 4 Dimensional space time, if recipients of matter-energy from collapse and re birth of the universe are enough to insure low relic GW. The existence of higher dimensions, in itself if the additional dimensions are small and compact will have no capacity to lower the frequency limit values of relic GW, as predicted by Giovannini, et al. in 1995.
基金Project supported by the National Key R&D Program of China(No.2022YFC3204303)the National Natural Science Foundation of China(Nos.12202503,12132018,and 52394254)。
文摘As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport significantly.Hence,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary layer.In this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary layer.Then,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel function.Consequently,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable transformation.The analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.
基金The National Key R&D Program of China under contract No.2022YFC3104805the National Natural Science Foundation of China under contract Nos 42276019,41706025 and 41976200+4 种基金the Innovation Team Plan for Universities in Guangdong Province under contract No.2019KCXTF021the First-class Discipline Plan of Guangdong Province under contract Nos 080503032101and 231420003the Program for Scientific Research Start-up Funds of Guangdong Ocean University under contract No.060302032106the Open Fund Project of Key Laboratory of Marine Environmental Information Technology(2019)Ministry of Natural Resources。
文摘This study aims to investigate characteristics of continental shelf wave(CSW)on the northwestern continental shelf of the South China Sea(SCS)induced by winter storms in 2021.Mooring and cruise observations,tidal gauge data at stations Hong Kong,Zhapo and Qinglan and sea surface wind data from January 1 to February 28,2021 are used to examine the relationship between along-shelf wind and sea level fluctuation.Two events of CSWs driven by the along-shelf sea surface wind are detected from wavelet spectra of tidal gauge data.The signals are triply peaked at periods of 56 h,94 h and 180 h,propagating along the coast with phase speed ranging from 6.9 m/s to18.9 m/s.The dispersion relation shows their property of the Kelvin mode of CSW.We develop a simple method to estimate amplitude of sea surface fluctuation by along-shelf wind.The results are comparable with the observation data,suggesting it is effective.The mode 2 CSWs fits very well with the mooring current velocity data.The results from rare current help to understand wave-current interaction in the northwestern SCS.
文摘The recently observed gravitational wave background is explained in terms of the quantum modification of the general relativity (Qmoger). Some UFO, FRB and supernova flares also can be explained in terms of Qmoger.
基金Supported by the National Natural Science Foundation of China(Nos.61871353,42006164)。
文摘Optical remote sensing has been widely used to study internal solitary waves(ISWs).Wind speed has an important effect on ISW imaging of optical remote sensing.The light and dark bands of ISWs cannot be observed by optical remote sensing when the wind is too strong.The relationship between the characteristics of ISWs bands in optical remote sensing images and the wind speed is still unclear.The influence of wind speeds on the characteristics of the ISWs bands is investigated based on the physical simulation experiments with the wind speeds of 1.6,3.1,3.5,3.8,and 3.9 m/s.The experimental results show that when the wind speed is 3.9 m/s,the ISWs bands cannot be observed in optical remote sensing images with the stratification of h_(1)∶h_(2)=7∶58,ρ_(1)∶ρ_(2)=1∶1.04.When the wind speeds are 3.1,3.5,and 3.8 m/s,which is lower than 3.9 m/s,the ISWs bands can be obtained in the simulated optical remote sensing image.The location of the band’s dark and light extremum and the band’s peak-to-peak spacing are almost not affected by wind speed.More-significant wind speeds can cause a greater gray difference of the light-dark bands.This provided a scientific basis for further understanding of ISW optical remote sensing imaging.
基金Supported by the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2023JJ10053)the National Natural Science Foundation of China(No.42276205)。
文摘The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.
基金the National Natural Science Foundation of China(Grant Nos.41831073,42174196,and 42374205)the Project of Stable Support for Youth Team in Basic Research Field,Chinese Academy of Sciences(CAS+4 种基金Grant No.YSBR-018)the Informatization Plan of CAS(Grant No.CAS-WX2021PY-0101)the Youth Cross Team Scientific Research project of the Chinese Academy of Sciences(Grant No.JCTD-2021-10)the Open Research Project of Large Research Infrastructures of CAS titled“Study on the Interaction Between Low-/Mid-Latitude Atmosphere and Ionosphere Based on the Chinese Meridian Project.”This work was also supported in part by the Specialized Research Fund and the Open Research Program of the State Key Laboratory of Space Weather.
文摘We derive the potential energy of gravity waves(GWs)in the upper troposphere and stratosphere at 45°S-45°N from December 2019 to November 2022 by using temperature profiles retrieved from the Constellation Observing System for Meteorology,Ionosphere,and Climate-2(COSMIC-2)satellite.Owing to the dense sampling of COSMIC-2,in addition to the strong peaks of gravity wave potential energy(GWPE)above the Andes and Tibetan Plateau,we found weak peaks above the Rocky,Atlas,Caucasus,and Tianshan Mountains.The land-sea contrast is responsible for the longitudinal variations of the GWPE in the lower and upper stratosphere.At 40°N/S,the peaks were mainly above the topographic regions during the winter.At 20°N/S,the peaks were a slight distance away from the topographic regions and might be the combined effect of nontopographic GWs and mountain waves.Near the Equator,the peaks were mainly above the regions with the lowest sea level altitude and may have resulted from convection.Our results indicate that even above the local regions with lower sea level altitudes compared with the Andes and Tibetan Plateau,the GWPE also exhibits fine structures in geographic distributions.We found that dissipation layers above the tropopause jet provide the body force to generate secondary waves in the upper stratosphere,especially during the winter months of each hemisphere and at latitudes of greater than 20°N/S.
文摘Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.
基金Z.Y.acknowledges the National Natural Science Foundation of China(Grant No.42074211)the Key Research Program of the Institute of Geology&Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-201904).
文摘A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the magnetosheaths of the Earth and other planets in the solar system,yet the understanding of mirror mode waves on extraterrestrial planets is not as comprehensive as that on the Earth.Using magnetic field data collected by the Cassini spacecraft,we found peak and dip types according to the magnetic morphology(i.e.,structures with higher or lower magnetic strengths than the background field).Moreover,mirror mode waves and electromagnetic ion cyclotron waves were found one after the other,implying that the two wave modes may evolve into one another in the Kronian magnetosheath.The results indicate that many fundamental plasma processes associated with the mirror mode structure exist in the Kronian magnetosheath.The energy conversion in Saturn’s magnetosheath may provide key insights that will aid in understanding giant planetary magnetospheric processes.
文摘There are great differences in the distribution characteristics of shock waves produced by ammunition explosions at different altitudes.At present,there are many studies on plain explosion shock waves,but there are few studies on the distribution characteristics of plateau explosion shock waves,and there is still a lack of complete analysis and evaluation methods.This paper compares and analyzes shock wave overpressure data at different altitudes,obtains the attenuation effect of different altitudes on the shock wave propagation process and proposes a calculation formula for shock wave overpressure considering the effect of altitude.The data analysis results show that at the same TNT equivalent and the same distance from the measuring point,the shock wave overpressure at high altitude is lower than that at low altitude.With the increase in the explosion center distance of the measuring point,the peak attenuation rate of the shock wave overpressure at high altitudes is smaller than that at low altitudes,and the peak attenuation rate of the shock wave overpressure at high altitudes gradually intensifies with increasing proportional distance.The average error between the shock wave overpressure and measured shock wave overpressure in a high-altitude environment obtained by using the above calculation formula is 11.1389%.Therefore,this method can effectively predict explosion shock wave overpressure in plateau environments and provides an effective calculation method for practical engineering tests.
基金supported by the National Natural Science Foundation of China(42222408,41931073)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021027)supported by the Key Research Program of the Institute of Geology&Geophysics,Chinese Academy of Sciences(grant IGGCAS-201904).
文摘The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.
文摘It is essential to assess the evolution of soil fabric as it has an important role in the mechanical responses of soils during complex loading conditions.This contribution carries out the physical experiments using three granular materials in the laboratory.The variations of compression and shear wave velocities(Vp and Vs)are investigated during load-unload cycles under dry and drained conditions.Supplementary discrete element method(DEM)simulations are performed to understand the evolution of soil fabric during the equivalent load-unload cycles using spherical particles.Vp and Vs are not always reversible even though the stress state regains its isotropic condition after unload,indicating that Vp and Vs are governed by not only the stress state but also the fabric change.The variations of Vp/Vs are density-and stress-dependent;a higher level of stress ratio(s01/s03)threshold is observed for denser packings to trigger a significant change in wave velocity ratio(Vp/Vs)for experimental results using spherical glass beads and simulation data using spherical particles.Considering the particle shape,a higher s01/s03 threshold is found for more angular particles than rounded particles.The DEM result reveals that Vp/Vs of spherical particles can be correlated linearly with the evolution of fabric ratio(Fver/Fhor)during loadunload in a pre-peak range under dry and drained conditions.
基金supported by Ministry of Higher Education through the FundamentalResearch Grant Scheme(FRGS)under a grant number of FRGS/1/2020/ICT09/UNIMAP/02/2.
文摘This article presents the generation of Orbital AngularMomentum(OAM)vortex waves with mode 1 using Uniform Circular Array(UCA)antenna.Two different designs,namely,UCA-1(4-element array antenna)and UCA-2(8-element array antenna),were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz(5G mid-band).The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique.The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value.The generated OAM waves were confirmed by measuring the null in the bore sight of their 2D radiation patterns,simulated phase distribution and intensity distribution.The measurement results agree well with the simulation results.Moreover,a detailed mode purity analysis of the generated OAM waves was carried out considering different factors.The investigation found that the greater the number of elements,the higher the purity of the generated OAM wave.Compared with other previous works,the proposed antenna design of this paper is very simple to design and fabricate.In addition,the proposed antennas are compact in design even at lower frequency band with very wide bandwidth to meet the requirements of 5G mid-band applications.