Wave Background Research Articles

Comparing Loon Superpressure Balloon Observations of Gravity Waves in the Tropics With Global Storm‐Resolving Models

AbstractSuperpressure balloons, which drift approximately on isopycnal surfaces, get displaced by gravity waves and are thus capable of detecting gravity wave signatures. The project Loon provides superpressure balloon data in the upper troposphere and lower stratosphere from 2011 to 2021. We compare Loon data from the 6 years of best data coverage with output of global storm‐resolving models from the DYnamics of the Atmospheric general circulation Modeled On Non‐hydrostatic Domains winter initiative in the tropics. We study the variance of the vertical velocity and, for the models, the gravity wave momentum flux as function of distance to closest convection. The models show large differences in the variance of the vertical wind velocity, which is crucial for calculating vertical gravity wave momentum fluxes. We find large differences between the models with respect to simulated convection, lateral propagation, and the wave background away from sources. We then sample balloons as models by optimizing the match of vertical wind distributions using a temporal low pass filter. The average distance the balloons travel during the optimum low pass filtering time turns out to correspond approximately to four times the model grid spacing. The functional dependence of the vertical velocity variance on distance to closest convection is similar between the models and the observations sampled as models. The robustness of this result across all models suggests that storm‐resolving models provide a useful resource for machine learning some characteristics of convectively generated gravity waves.

Inverse Cascade Spectrum of Gravity Waves in the Presence of a Condensate: A Direct Numerical Simulation.

During the set of direct numerical simulations of the forced isotropic turbulence of surface gravity waves in the framework of primordial dynamical equations, the universal inverse cascade spectrum was observed. The slope of the spectrum is the same (in the margin of error) for different levels of pumping and nonlinearity as well as dissipation present in the system. In all simulation runs formation of the inverse cascade spectrum was accompanied by the appearance of a strong long wave background (condensate). The observed slope of the spectrum ∼k^{-3.07} is different from the constant wave action flux solution predicted by the wave turbulence theory ∼k^{-23/6}.

Rational soliton solutions in the nonlocal coupled complex modified Korteweg–de Vries equations

Abstract In this article, our work oversees with the nonlocal coupled complex modified Korteweg–de Vries equations (cmKdV), which is a nonlocal generalization for coupled cmKdV equations. The n-fold Darboux transformation (DT) is constructed in the form of determinants for the nonlocal coupled cmKdV equations. Via generalized DT method, we obtain the rational soliton solutions describing M-shaped soliton, W-shaped soliton, and the interactions on the plane wave and periodic background. The results can be useful to study the dynamical behaviors of soliton solutions in nonlocal wave models.

Stochastic Background of Gravitational Waves Generated by Black Hole MACHO Binaries in the Galaxy

Stochastic Background of Gravitational Waves Generated by Black Hole MACHO Binaries in the Galaxy

CP -violating observables in four-body B→ϕ(→KK¯)K*(→Kπ) decays

We analyze the four-body $B\ensuremath{\rightarrow}\ensuremath{\phi}(\ensuremath{\rightarrow}K\overline{K}){K}^{*}(\ensuremath{\rightarrow}K\ensuremath{\pi})$ decays in the perturbative QCD approach, where the invariant mass of the $K\overline{K}$ ($K\ensuremath{\pi}$) system is limited in a window of $\ifmmode\pm\else\textpm\fi{}15\text{ }\text{ }\mathrm{MeV}$ ($\ifmmode\pm\else\textpm\fi{}150\text{ }\text{ }\mathrm{MeV}$) around the nominal $\ensuremath{\phi}({K}^{*}(892))$ mass. In addition to the dominant $P$-wave resonances, two important $S$-wave backgrounds in the selected invariant mass region are also accounted for. Angular momentum conservation allows six helicity amplitudes to contribute, including three $P$ waves, two single $S$ waves, and one double $S$ wave, in the decays under study. We calculated the branching ratio for each component and found sizable $S$-wave contributions, which coincide roughly with the experimental observation. The obtained branching ratios of ${B}^{0(+)}\ensuremath{\rightarrow}\ensuremath{\phi}{K}^{*0(+)}$ are comparable with the previous theoretical predictions and support the experimental measurements, whereas the predicted $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}\ensuremath{\phi}{\overline{K}}^{*0})$ is an order of magnitude smaller than the current world average in its central value. The longitudinal polarizations are predicted to be around 0.7, consistent with previous PQCD results but larger than the world average values. Aside from the direct $CP$ asymmetries, the true and fake triple product asymmetries, originating from the interference between the perpendicular polarization amplitude and other helicity amplitudes, are also calculated in this work. In the special case of the neutral modes, both the direct $CP$ asymmetries and true triple product asymmetries are expected to be zero due to the vanishing weak phase difference. The direct $CP$ asymmetries for the ${B}^{+}$ mode are predicted to be tiny, of order ${10}^{\ensuremath{-}2}$, since the tree contributions are suppressed strongly with respect to the penguin ones. The true triple product asymmetries have shown no significant deviations from zero. In contrast, large fake asymmetries are observed in these decays, indicating the presence of significant final-state interactions. We give the theoretical predictions of the $S$-wave induced triple product asymmetries for the first time, which is consistent with current LHCb data and would be checked with future measurements from Belle and BABAR experiments if the $S$-wave components can be properly taken into account in the angular analysis.

Gravitational waves from first-order phase transitions in Majoron models of neutrino mass

We show how the generation of right-handed neutrino masses in Majoron models may be associated with a first-order phase transition and accompanied by the production of a stochastic background of gravitational waves (GWs). We explore different energy scales with only renormalizable operators in the effective potential. If the phase transition occurs above the electroweak scale, the signal can be tested by future interferometers. We consider two possible energy scales for phase transitions below the electroweak scale. If the phase transition occurs at a GeV, the signal can be tested at LISA and provide a complementary cosmological probe to right-handed neutrino searches at the FASER detector. If the phase transition occurs below 100 keV, we find that the peak of the GW spectrum is two or more orders of magnitude below the putative NANOGrav GW signal at low frequencies, but well within reach of the SKA and THEIA experiments. We show how searches of very low frequency GWs are motivated by solutions to the Hubble tension in which ordinary neutrinos interact with the dark sector. We also present general calculations of the phase transition temperature and Euclidean action that apply beyond Majoron models.

Nonlinear dynamics of a charged particle in a strong non-null knot wave background

In this paper, we study the dynamics of a charged particle interacting with the non-null electromagnetic knot wave background. We analyze the classical system in the Hamilton–Jacobi formalism and find the action, the linear momentum and the trajectory of the particle. Also, we calculate the effective mass and the emitted radiation along the knot wave. Next, we quantize the system in the classical strong knot wave background by using the strong-field QED canonical formalism. We explicitly construct the Furry picture and calculate the Volkov solutions of the Dirac equation. As an application, we discuss the one-photon Compton effect where we determine the general form of the S-matrix. Also, we discuss in detail the first partial amplitudes in the transition matrix in two simple backgrounds and show that there is a pair of states for which these amplitudes are identical.

Analytical matter wave solutions of a (2+1)-dimensional partially nonlocal distributed-coefficient Gross–Pitaevskii equation with a linear potential

A (2+1)-dimensional partially nonlocal distributed-coefficient Gross–Pitaevskii equation with a linear potential and nonlinearity localized in x direction and non-localized in y-direction is considered, and a mapping relationship between a distributed-coefficient equation and a solvable constant-coefficient one is provided. Utilizing this relationship, and via the Darboux transformation and Hirota method, exact analytical matter wave solutions are found. These solutions contain bright and dark multi-soliton solutions, and bright and dark soliton solutions on wave background. We hope that these results would be useful for enriching and understanding matter wave phenomena in the nonlocal media.

Seizure initiation in infantile spasms vs. focal seizures: proposed common cellular mechanisms.

Infantile spasms (IS) and seizures with focal onset have different clinical expressions, even when electroencephalography (EEG) associated with IS has some degree of focality. Oddly, identical pathology (with, however, age-dependent expression) can lead to IS in one patient vs. focal seizures in another or even in the same, albeit older, patient. We therefore investigated whether the cellular mechanisms underlying seizure initiation are similar in the two instances: spasms vs. focal. We noted that in-common EEG features can include (i) a background of waves at alpha to delta frequencies; (ii) a period of flattening, lasting about a second or more - the electrodecrement (ED); and (iii) often an interval of very fast oscillations (VFO; ~70 Hz or faster) preceding, or at the beginning of, the ED. With IS, VFO temporally coincides with the motor spasm. What is different between the two conditions is this: with IS, the ED reverts to recurring slow waves, as occurring before the ED, whereas with focal seizures the ED instead evolves into an electrographic seizure, containing high-amplitude synchronized bursts, having superimposed VFO. We used in vitro data to help understand these patterns, as such data suggest cellular mechanisms for delta waves, for VFO, for seizure-related burst complexes containing VFO, and, more recently, for the ED. We propose a unifying mechanistic hypothesis - emphasizing the importance of brain pH - to explain the commonalities and differences of EEG signals in IS versus focal seizures.

Response of the western North Pacific subtropical ocean to the slow-moving super typhoon Nanmadol

Based on in-situ observation, satellite and reanalysis data, responses of the western North Pacific subtropical ocean (WNPSO) to the slow-moving category 5 super typhoon Nanmadol in 2011 are analyzed. The dynamical response is dominated by near-inertial currents and Ekman currents with maximum amplitude of 0.39 m/s and 0.15 m/s, respectively. The near-inertial currents concentrated around 100 m below the sea surface and had an e-folding timescale of 4 days. The near-inertial energy propagated both upward and downward, and the vertical phase speed and wavelength were estimated to be 5 m/h and 175 m, respectively. The frequency of the near-inertial currents was blue-shifted near the surface and red-shifted in ocean interior which may relate to wave propagation and/or background vorticity. The resultant surface cooling reaches −4.35°C and happens when translation speed of Nanmadol is smaller than 3.0 m/s. When Nanmadol reaches super typhoon intensity, the cooling is less than 3.0°C suggesting that the typhoon translation speed plays important roles as well as typhoon intensity in surface cooling. Upwelling induced by the slow-moving typhoon wind leads to typhoon track confined cooling area and the right-hand bias of cooling is slight. The mixed layer cooling and thermocline warming are induced by wind-generated upwelling and vertical entrainment. Vertical entrainment also led to mixed layer salinity increase and thermocline salinity decrease, however, mixed layer salinity decrease occurs at certain stations as well. Our results suggest that typhoon translation speed is a vital factor responsible for the oceanic thermohaline and dynamical responses, and the small Mach number (slow typhoon translation speed) facilitate development of Ekman current and upwelling.

Chinese Immigrants and Underground Lotteries in South Africa: Negotiating Spaces at the Cusp of a Racial–Capitalist Order

This article reviews the history of an illegal Chinese-run numbers game or lottery in South Africa. Structurally very similar to games played by Chinese immigrants in the USA, fahfee operations (or banks) provided an illicit accumulation strategy, which allowed entrepreneurial Chinese immigrants to survive at the margins of a discriminatory racial–capitalist order, and to use these enterprises as a platform to enter the mainstream white economy. Fahfee was a tactic through which the subordinate were able to contest and negotiate the repressive strategies of the socio-political elite. The discussion of fahfee is set against the background of successive waves of Chinese immigration to South Africa, from the slaves and convict labour imported by the Dutch East India Company in the 17th century to more recent immigration from Taiwan and the Peoples Republic of China. The article draws on a wide variety of historical material, the literature on both gambling and Chinese migration, and interviews with contemporary fahfee bankers.

Measuring stochastic gravitational-wave energy beyond general relativity

Gravity theories beyond general relativity (GR) can change the properties of gravitational waves: their polarizations, dispersion, speed, and, importantly, energy content are all heavily theory- dependent. All these corrections can potentially be probed by measuring the stochastic gravitational- wave background. However, most existing treatments of this background beyond GR overlook modifications to the energy carried by gravitational waves, or rely on GR assumptions that are invalid in other theories. This may lead to mistranslation between the observable cross-correlation of detector outputs and gravitational-wave energy density, and thus to errors when deriving observational constraints on theories. In this article, we lay out a generic formalism for stochastic gravitational- wave searches, applicable to a large family of theories beyond GR. We explicitly state the (often tacit) assumptions that go into these searches, evaluating their generic applicability, or lack thereof. Examples of problematic assumptions are: statistical independence of linear polarization amplitudes; which polarizations satisfy equipartition; and which polarizations have well-defined phase velocities. We also show how to correctly infer the value of the stochastic energy density in the context of any given theory. We demonstrate with specific theories in which some of the traditional assumptions break down: Chern-Simons gravity, scalar-tensor theory, and Fierz-Pauli massive gravity. In each theory, we show how to properly include the beyond-GR corrections, and how to interpret observational results.

Mathematical Modeling of Rogue Waves: A Survey of Recent and Emerging Mathematical Methods and Solutions

Anomalous waves and rogue events are closely associated with irregularities and unexpected events occurring at various levels of physics, such as in optics, in oceans and in the atmosphere. Mathematical modeling of rogue waves is a highly active field of research, which has evolved over the last few decades into a specialized part of mathematical physics. The applications of the mathematical models for rogue events is directly relevant to technology development for the prediction of rogue ocean waves and for signal processing in quantum units. In this survey, a comprehensive perspective of the most recent developments of methods for representing rogue waves is given, along with discussion of the devised forms and solutions. The standard nonlinear Schrödinger equation, the Hirota equation, the MMT equation and other models are discussed and their properties highlighted. This survey shows that the most recent advancement in modeling rogue waves give models that can be used to establish methods for the prediction of rogue waves in open seas, which is important for the safety and activity of marine vessels and installations. The study further puts emphasis on the difference between the methods and how the resulting models form the basis for representing rogue waves in various forms, solitary or with a wave background. This review has also a pedagogic component directed towards students and interested non-experts and forms a complete survey of the most conventional and emerging methods published until recently.

A Pulsar Time Scale Based on Parkes Observations in 1995–2010

Timing of highly stable millisecond pulsars provides the possibility of independently verifying terrestrial time scales on intervals longer than a year. An ensemble pulsar time scale is constructed based on pulsar timing data obtained on the 64-m Parkes telescope (Australia) in 1995--2010. Optimal Wiener filters were applied to enhance the accuracy of the ensemble time scale. The run of the time--scale difference PT$_{ens}$ $-$ TT(BIPM2011) does not exceed $0.8 {\pm} 0.4$ $\mu s$ over the entire studied time interval. The fractional instability of the difference $_{ens}$ $-$ TT(BIPM2011) over 15 years is ${\sigma_z} = (0.6\pm 1.6){\cdot}10^{-15}$, which corresponds to an upper limit for the energy density of the gravitational--wave background ${\Omega_g}h^2 {\sim} 10^{-10}$ and variations in the gravitational potential ${\sim} 10^{-15}$ Hz at the frequency $2{\cdot}10^{-9}$.

The Charge Structures of Aether and Substance

The hypothesis of the charge structures matter serves as the basis for defining the inner energies of “rest” an electron: Ee=αc/(2πRe)[s﹣1]; a neutrino: En=Eeα3; a proton: Ep=Ee(α-2-3α-1). “Relict” radiation is regarded as the wave background is caused by charges oscillations of the aether. Charge pair known as a neutrino is the elementary structure of the aether and participant of the energy and charges exchange reactions between the ethereal and in-ert structures. The internal spin dynamics of the charge structures of particles creates their inertness. The electron mass of “rest” is defined as the time density on its shell that forms the space-time unity: Me=α/(2πRec)[s/m2]. Factors of randomness and periodicity in the radioactivity phenomenon are explained. The ethereal concept of the antiparticles origin is proposed.

The design and research of the shared kitchen system in the hospital

The shared economy has been developing rapidly with low cost, low consumption and high environmental efficiency features under the background of internet waves. The shared economy model has emerged in housing, catering, and travel. As people look forward to high quality of life and their social interaction need, the shared kitchen platform arises at the right moment. This paper takes the shared kitchen as an example, focusing on the patients and their caregivers, the existing shared kitchens and its service platform as well as the space system design and human-computer interaction of the shared kitchen have been investigated and analysized. Taking the "high efficiency, the intelligence and the humanization" as the design principles, we are committed to exploring new directions for modular kitchen design under the background of shared economy.

SAR imaging simulation of ship-generated internal wave wake in stratified ocean

Simulation of synthetic aperture radar (SAR) imaging of ship-generated internal wave wake in stratified ocean is conducted through the combination of scattering and modulation effects under the background of wind waves. With the derived surface velocity of internal wave wake from the velocity potential, a reconstruction of the wave elevation is implemented by means of the frequency decomposition technique. Based on the hydrodynamic model, the facet scattering model is presented for the fully polarimetric backscattering and the velocity bunching imaging model is applied to the SAR image simulation of surface waves with an embedded internal wave wake. Numerical simulations show that the wave patterns of internal wave wake, which modulates the distribution of Bragg waves on sea surface, are closely dependent on ship speed. And the conditions are classified for a good visibility of internal wave wake in SAR image. Besides, the great agreement with measurement strongly verifies the validity of the simulation.

Effects of gravitational waves on the polarization of pulsars

The polarization of electromagnetic waves in the presence of a gravitational wave is analyzed. The rotation of the polarization angle and the Stokes parameters are deduced. A possible application to the detection of stochastic background of gravitational waves is proposed as a complement to the pulsar timing method.

Profile stochasticity in PSR J1909−3744

We extend the recently introduced Bayesian framework `Generative Pulsar Timing Analysis' to incorporate both pulse jitter (high frequency variation in the arrival time of the pulse) and epoch to epoch stochasticity in the shape of the pulse profile. This framework allows for a full timing analysis to be performed on the folded profile data, rather than the site arrival times as is typical in most timing studies. We apply this extended framework both to simulations, and to an 11 yr, 10 cm data set for PSR J1909$-$3744. Using simulations, we show that temporal profile variation can induce timing noise in the residuals that when performing a standard timing analysis is highly covariant with the signal expected from a gravitational wave (GW) background. When working in the profile domain, these variations are de-correlated from the expected GW signal, resulting in significant improvement in the obtained upper limits. Using the PSR J1909$-$3744 data set from the Parkes Pulsar Timing Array project, we find significant evidence for systematic high-frequency profile variation resulting from non-Gaussian noise in the oldest observing system, but no evidence for either detectable pulse jitter, or low-frequency profile shape variation. Using our profile domain framework we therefore obtain upper limits on a red noise process with a spectral index of $\gamma = 13/3$ of $1\times10^{-15}$, consistent with previously published limits.

Review of the possible role of self-ordering scalar fields in production of a stochastic background of gravitational waves

A primordial gravitational wave background is a hallmark of inflationary cosmology. The recent announcement made by the BICEP2 collaboration of a possible measurement of B-mode polarization of the CMB on degree scales has produced an abundance of ideas and speculations on how such a signal constrains the inflationary paradigm, or possible alternative mechanisms of gravitational wave production. Here the possibility of a contribution to the gravitational wave background from the relaxation of a scalar field after a global phase transition is reviewed. The general contribution to the overall power is shown, and it is then demonstrated that if the BICEP2 result were to hold, this mechanism could at best produce a very small fraction of the measured tensor power.