Inhomogeneous Contributions Research Articles

Direct Evidence for Diverse Source Complexity in Small Earthquakes (Mw 3.3–5.0) Obtained from Near-Source Borehole Seismic Data

Abstract Small earthquakes (Mw <5) may have a similar degree of complexity as large earthquakes. However, their seismic waveforms are strongly distorted during wave propagation, making their complexity challenging to resolve. In many cases, the source parameters of small events are determined based on models that assume their source patterns are simple. In this study, to directly examine the source complexities in small events, we examined high-quality near-source (<8 km) seismic waveforms recorded by two excellent downhole sensors in Japan. The results show that the P waveforms of microearthquakes (Mw <2) are always simple at the sensors and agree well with the synthetic waveforms based on a 1D structure up to 20 Hz. The microearthquake waveforms in this frequency band essentially represent path effects besides the static source effect, suggesting that the contribution of structural inhomogeneity to the observed waveforms is small. Taking advantage of this, we inferred the moment rate functions of 164 Mw 3.3–5.0 events from the shapes of the direct P waves. They showed diversity in their complexity, and even conservatively estimated, 25% of the events had multiple subevents. The results suggest that methods that account for complexity, rather than those that assume a simple source pattern, are required to characterize even small events.

A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution.

We present the development of a versatile apparatus for 6.2eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved μ-ARPES). With a combination of tunable spatial resolution down to ∼11 μm, high energy resolution (∼11meV), near-transform-limited temporal resolution (∼280fs), and tunable 1.55eV pump fluence up to 3 mJ/cm2, this time-resolved μ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved μ-ARPES on a ∼30 μm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.

Frequency-domain hydroelastic stress analysis of floating structures under spatially inhomogeneous wave field

This paper presents a frequency-domain method for the stress analysis of flexible floating structures exposed to a spatially inhomogeneous wave field. A hydroelastic model is developed for the continuous structure, wherein discrete rigid modules are connected by elastic beams with equivalent stiffness. The inhomogeneous wave field is divided into wave regions characterized by constant wave parameters. By assigning distinct wave parameters to modules based on their respective positions, the global hydroelastic equation is established to capture the wave inhomogeneity. To compute the stress, external loads in the hydroelastic equation, comprising hydrodynamic and hydrostatic restoring pressures, as well as inertia forces, are mapped onto the finite element model of the continuous structure, enabling stress calculation by the quasi-static method. Variations in wave directions and heights along the longitudinal direction of the structure are introduced with the aim of exploring the effect of the wave inhomogeneity on the stress. A deliberately flexible barge is constructed to evaluate the stress resulting from global structural vibrations. The results demonstrate a significant contribution of wave inhomogeneity to the stress, particularly during structural resonance frequencies. Moreover, an exclusive phenomenon is observed whereby the inhomogeneous wave field induces stress due to anti-symmetric vibrations under beam sea conditions.

A new perspective on skin-friction contributions in adverse-pressure-gradient turbulent boundary layers

For adverse-pressure-gradient turbulent boundary layers, the study of integral skin-friction contributions still poses significant challenges. Beyond questions related to the integration boundaries and the derivation procedure, which have been thoroughly investigated in the literature, an important issue is how different terms should be aggregated. The nature of these flows, which exhibit significant in-homogeneity in the streamwise direction, usually results in cancellation between several contributions with high absolute values. We propose a formulation of the identity derived by Fukagata et al. (2002), which we obtained from the convective form of the governing equations. A new skin-friction contribution is defined, considering wall-tangential convection and pressure gradient together. This contribution is related to the evolution of the dynamic pressure in the mean flow. The results of the decomposition are examined for a broad range of pressure-gradient conditions and different flow-control strategies. We found that the new formulation of the identity allows to readily identify the different regimes of near-equilibrium conditions and approaching separation. It also provides a more effective description of control effects. A similar aggregation between convection and pressure-gradient terms is also possible for any other decomposition where in-homogeneity contributions are considered explicitly.

Effect of Chemical Inhomogeneity on the Dielectric and Impedance Behaviors of Bismuth Sodium Titanate Based Relaxors

Different levels of Nb2O5 substitution in 0.66(Bi0.5Na0.5)TiO3−0.06BaTiO3−0.28(Bi0.2Sr0.7)TiO3 (BS-xNb) lead-free relaxors were prepared to investigate the effect of chemical heterogeneity on the dielectric and impedance behaviors. X-ray diffraction reveals that the secondary phase gradually increases in number and intensity as the dopant increases. The substitution of less Nb5+ for Ti4+ leads to reduced electronic conductivity and dielectric loss, which is attributed to the inhibition of oxygen vacancies and associated electron. It is found that more valence electron defects are generated to cause charge leakage by introducing excess Nb2O5. Moreover, the addition of Nb2O5 doping enhances the disorder and facilitates the transition of the nonergodic to ergodic relaxor phase. The ferroelectric ergodic long-range order is further disrupted and promotes the formation of local defect fields and high-temperature polar nanoregions. These effects enhance the relaxation behavior with decreased remnant polarization and form a broadly flat dielectric platform. Meanwhile, BS-2Nb exhibits attractively high recoverable energy storage density and efficiency at a relatively low electric field with stability against frequency and temperature. Combined with the complex impedance characteristics, the leakage contribution of the chemical inhomogeneity introduced by excess Nb2O5 is presented, demonstrating the significance of regulating the dielectric performance of bismuth sodium titanate-based relaxors.

Turbulent secondary flows in low aspect ratio open-channels over heterogeneous surfaces: Anisotropy in forces

Studies of turbulent flows over heterogeneous surfaces revealed elevated turbulent kinetic energy and Reynolds shear stress in low-momentum-path regions. These regions induce large-scale multi-cellular secondary flows. The aim of the current study is to analyze the influence of these regions on drag, lift, and lateral forces acting on spherical particles at different exposure levels, thereby addressing the hitherto unknown contribution of the spanwise inhomogeneities. For this reason, numerical simulations of turbulent open-channel flow with varying aspect ratio (AR=1,3,5) over single-sized spherical particles with diameter D were studied. Ensemble-averaged cross-flow velocity vectors showed large-scale secondary flows to penetrate in-between the spherical particles, therefore stretching over the entire flow depth. Their magnitude above 0.8D was observed to range between 12.9%and14.9% of U. Strong tertiary vortices in the vicinity of the lateral walls were identified by analysis of swirl strength. Triple decomposition of streamwise velocity fluctuations showed strong backflow at the trailing edge of the spherical particles in high-momentum-path (HMP) regions. Furthermore, it was found that drag forces are higher in HMPs, which is attributed to the larger streamwise pressure gradient.

Magnetic energy dissipative factors of spin-coated Y[formula omitted]Fe[formula omitted]O12 thin films

Y3Fe5O12 (YIG) is a ferrimagnetic insulator that shows significant potential in various applications such as spin pumping and optical devices. In the case of YIG, the uncompensated antiferromagnetic coupled Fe3＋ ions originate the ferrimagnetic ordering. A homogeneous YIG thin film with lower Gilbert damping constant is essential for its industrial applications. Therefore, the YIG’s intrinsic and extrinsic magnetic energy dissipative factors are crucial to explore. Here, we report the growth of uniform polycrystalline YIG thin films on thermally oxidized Si (100) substrates. X-ray diffraction confirms the single-phase formation of YIG. Surface morphology and thickness on thin films are studied using scanning electron microscopy. X-ray photoemission is used to probe the valence state of constituent elements of the ferrimagnetic thin films with saturation magnetization 3.11 μB/f.u. The lowest Gilbert damping constant (α) = 4.754 × 10−3 with an inhomogeneous contribution to the linewidth of 5.04 mT is observed due to extrinsic inhomogeneous growth of the deposited films.

Study of growth and broadband FMR spectroscopy in PLD grown Y3Fe5O12/Gd3Ga5O12 thin films

We report the structural and magnetization dynamics of pulsed laser ablated Y3Fe5O12 (YIG) thin films grown on gadolinium gallium garnet (GGG[110]) substrate. The co-planar waveguide ferromagnetic resonance measurement was performed to study the thickness and inhomogeneity effect on damping constant. We also estimated the effective demagnetization () value which was lower than that of single-crystalline bulk YIG. A detailed line width analysis revealed the significant two-magnon scattering and inhomogeneity contribution to damping which varied for different thickness films. The Gilbert damping constant (α) of the grown film was found to be lowest in the case of 100 nm film (≈3 × 10−4), and the corresponding inhomogeneous broadening (ΔH O) was recorded to be 77 Oe. Further angular measurements on 100 nm thin film revealed the presence of strong uniaxial magnetic anisotropy field of 735 Oe at 10 GHz RF frequency.

Designing of semiconductive cotton fabrics based on poly (propynyl benzo thiazolone) with UV protection and antibacterial properties

Our research aimed to prepare semiconductive textile with multifunction activity such as hydrophobicity, antibacterial, and UV protection. Herein, propynyl benzo thiazolone (TH) and its polymer (PTH) were as-synthesized and investigated by FT-IR analysis. Further, the cotton fabrics were grafted in situ with each poly (propynyl benzo thiazolone) and with the as-synthesized hydrogel based on gelatin/PTH (PTH-G-T). The PTH-T and PTH-G-T were investigated by (FT-IR), (SEM), UV protection (UPF), and contact angle, and further, their electrical properties were studied by impedance spectroscopy, and dc conductivity of PTH, PTH-T, and PTH-T-G obtained at low frequency exhibited good conductivity upto 10-4 S cm−1, 4.5x10-8 and 1.7x10-7 S cm−1, respectively. An equivalent circuit model was used to investigate the impedance spectra of PTH-T and PTH-G-T samples. The impedance could be split into two components. One component was identified as an inhomogeneity contribution, while the other was recognized as an intrinsic conduction component that exhibited characteristic semiconductor behavior. Various conduction experiments and theories are used to explain the results. Besides, they have good antibacterial and excellent UV protection. The outcomes assured the ability usage of the treated cotton fabrics in health monitoring apparel.

Spectroscopy of Alkali Atoms in Solid Matrices of Rare Gases: Experimental Results and Theoretical Analysis

We present an experimental and theoretical investigation of the spectroscopy of dilute alkali atoms in a solid matrix of inert gases at cryogenic temperatures, specifically Rubidium atoms in a solid Argon or Neon matrix, and related aspects of the interaction energies between the alkali atoms and the atoms of the solid matrix. The system considered is relevant for matrix isolation spectroscopy, and it is at the basis of a recently proposed detector of cosmological axions, exploiting magnetic-type transitions between Zeeman sublevels of alkali atoms in a magnetic field, tuned to the axion mass, assumed in the meV range. Axions are one of the supposed constituents of the dark matter (DM) of the Universe. This kind of spectroscopy could be also relevant for the experimental search of new physics beyond the Standard Model, in particular the search of violations of time-reversal or parity-charge-conjugation (CP) symmetry. In order to efficiently resolve the axion-induced transition in alkali-doped solid matrices, it is necessary to reduce as much as possible the spectral linewidth of the electronic transitions involved. The theoretical investigation presented in this paper aims to estimate the order of magnitude of the inhomogeneous contribution to the linewidth due to the alkali–matrix interactions (Coulomb/exchange and dispersion), and to compare the theoretical results with our experimental measurements of spectra of dilute Rubidium atoms in Argon and Neon solid matrix. The comparison of the expected or measured spectral linewidths will be important for selecting the most appropriate combination of alkali atoms and matrix inert elements to be used in the proposed axion detection scheme. It is finally suggested that dilute Lithium atoms diffused in a cold parahydrogen solid matrix could be, overall, a good system upon which the proposed detector could be based.

Is a single late SPECT/CT based kidney 177Lu-dosimetry superior to hybrid dosimetry with sequential multiple time-point whole-body planar scans in combination with an early SPECT/CT?

PurposeThe aim is to assess the impact of different imaging-protocols on image-based kidney dosimetry in 177Lu labelled peptide receptor radiotherapies. MethodsKidney data of five [177Lu]Lu-OPS201 injected pigs and a 3D printed phantom were used for comparing the absorbed doses and time-integrated activity coefficients calculated based on the following imaging-protocols: A-) multiple time-point SPECT/CTs, B-) multiple time-point planar scans in combination with one SPECT/CT, C-) single time-point SPECT/CT. In addition, the influence of late scan time-points on kidney dosimetry was investigated by sequentially eliminating scan data at > 100 h from the pig/phantom datasets for imaging-protocols A and B. ResultsCompared to imaging-protocol A, absorbed doses based on imaging-protocols B and C (scans at > 24 h post-injection) were always lower (differences > 34%). The best agreement in absorbed dose was achieved by imaging-protocol C at ∼ 100 h post-injection (difference: 4%). Regarding the phantom/pig experiments, eliminating scan data at > 100 h post-injection increased the time-integrated activity coefficients calculated based on imaging-protocols A and B by up to 83%. ConclusionWhile imaging-protocol A is accurate if scans at >∼100 h are included, it is time-consuming. In addition to being time-consuming, imaging-protocol B shows high differences associated with organ-count overlay, a lack of accuracy concerning the geometric mean based 2D attenuation correction, and 2D background subtraction due to the inhomogeneous and time-varying background contributions. Our findings indicate that dosimetry based on imaging-protocol C, if appropriately performed, provides similar kidney absorbed doses compared to imaging-protocol A, while only a single scan time-point is necessary.

Homogeneous Optical Line Widths in Hybrid Ruddlesden–Popper Metal Halides Can Only Be Measured Using Nonlinear Spectroscopy

The homogeneous photoluminescence spectral linewidth in semiconductors carries a wealth of information on the coupling of primary photoexcitations with their dynamic environment as well as between multi-particles. In the limit in which inhomogeneous broadening dominates the total optical linewidths, the inhomogeneous and homogeneous contributions can be rigorously separated by temperature-dependent %linear spectral measurements such as steady-state photoluminescence spectroscopy. This is possible because the only temperature-dependent phenomenon is optical dephasing, which defines the homogeneous linewidth, since this process is mediated by scattering with phonons. However, if the homogeneous and inhomogeneous linewidths are comparable, as is the case in hybrid Ruddlesden-Popper metal halides, the temperature dependence of linear spectral measurement \emph{cannot} separate rigorously the homogeneous and inhomogeneous contributions to the total linewidth because the lineshape does \emph{not} contain purely Lorentzian components that can be isolated by varying the temperature. Furthermore, the inhomogeneous contribution to the steady-state photoluminescence lineshape is not necessarily temperature independent if driven by diffusion-limited processes, particularly if measured by photoluminescence. Nonlinear coherent optical spectroscopies, on the other hand, do permit separation of homogeneous and inhomogeneous line broadening contributions in all regimes of inhomogeneity. Consequently, these offer insights into the nature of many-body interactions that are entirely inaccessible to temperature-dependent linear spectroscopies. When applied to Ruddlesden-Popper metal halides, these techniques have indeed enabled us to quantitatively assess the exciton-phonon and exciton-exciton scattering mechanisms.

Transition of a binary solution into an inhomogeneous phase

ABSTRACT The thermodynamics of phase transitions of binary solutions into spatially inhomogeneous one-dimensional states is studied theoretically by taking into account nonlinear effects. It is shown that below the spinodal decomposition temperature there first occurs a phase stratification, and at a lower temperature, after reaching the maximum possible stratification, there occurs a second-order transition into the phase with concentration waves. The contribution of inhomogeneity to the entropy and heat capacity of phases is calculated and the phase diagram in the coordinates temperature – average concentration is constructed.

Proceedings to the 7th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA)

Proceedings to the 7th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA)

Anisotropic Cahn-Hilliard free energy and interfacial energies for binary alloys with pairwise interactions

The original Cahn-Hilliard derivation of the contribution of compositional inhomogeneity to the free energy of a binary alloy with pairwise interactions is extended to include higher-order inhomogeneity terms. For alloys on a cubic lattice, the coefficient of the first inhomogeneity is a second-rank tensor and reduces to a scalar, but it is shown that the second order and the third order inhomogeneity terms are weighted by fourth-rank and sixth-rank tensors, thus resulting in anisotropic contributions. Furthermore, each interaction shell generates a unique set of inhomogeneity coefficients that is determined by the set of vectors connecting an atom to its neighbors on that shell. These coefficients are calculated for fcc and bcc alloys with interactions up fourth nearest neighbors. Phase field simulations based on these extended Cahn-Hilliard free energies are performed to measure interface free energies along specific crystallographic directions as a function of temperature, and to obtain the equilibrium shape of precipitates. Interface free energies, and the resulting anisotropies, are compared to those obtained by discrete models and Monte Carlo simulations.

Inhomogeneous crust-mantle interaction and Triassic tectonic escape of a Proterozoic microplate: A tale of the Bikou Terrane

Compressional stress in collisional orogenic belts open a free boundary for the lateral extrusion of rigid blocks. Here we trace the history of tectonic escape of a Proterozoic microplate and the associated inhomogeneous crust-mantle processes from magmatic records in the Bikou Terrane, which is the largest microblock located among the North China Block, South China Block and Songpan-Ganzi Orogenic Belt. Zircon U-Pb geochronology indicates that the Triassic granitoid intrusions in the Bikou Terrane emplaced at 220–210 Ma. Petrographical, whole-rock geochemical and isotopical features suggest that the granitoids derived from the partial melting of lower crust, with inhomogeneous contribution of mafic magma derived from partial melting of subcontinental lithospheric mantle. Compared with the Yangba pluton in northeastern Bikou Terrane, the five intrusions in the southwestern Bikou Terrane display relatively lower REE concentrations, more negative Eu anomalies (δEu = 0.24–0.93), and lower Nb/Ta and Zr/Hf ratios with the values of 14–20 and 37–45. Furthermore, they display higher (87Sr/86Sr) i from 0.7050 to 0.7075 and lower εNd(t) from −9.4 to −4.7. These features imply that the granitic intrusions in southwestern Bikou Terrane were primary derived from the partial melting of the lower crust with lesser input of mantle materials than the Yangba pluton, indicating inhomogeneous crust-mantle interaction in the Bikou Terrane. We calculated the Moho depth of northeast and southwest Bikou Terrane as ~60 km and ~ 40–50 km, respectively. We propose that the Bikou Terrane escaped southwestward in Late Triassic following a transition in the stress regime of compression from NE-SW to NW-SE, in addition to the slab break-off from east to west. The lateral extrusion resulted in the inhomogenous crust-mantle interaction.

Ultra-high-resolution software-defined photonic terahertz spectroscopy

A novel technique for high-resolution 1.5 µ m photonics-enabled terahertz (THz) spectroscopy using software control of the illumination spectral line shape (SLS) is presented. The technique enhances the performance of a continuous-wave THz spectrometer to reveal previously inaccessible details of closely spaced spectral peaks. We demonstrate the technique by performing spectroscopy on L i Y F 4 : H o 3 + , a material of interest for quantum science and technology, where we discriminate between inhomogeneous Gaussian and homogeneous Lorentzian contributions to absorption lines near 0.2 THz. Ultra-high-resolution ( < 100 H z full-width at half maximum) frequency-domain spectroscopy with quality factor Q > 2 × 10 9 is achieved using an exact frequency spacing comb source in the optical communications band, with a custom uni-traveling-carrier photodiode mixer and coherent down-conversion detection. Software-defined time-domain modulation of one of the comb lines is demonstrated and used to resolve the sample SLS and to obtain a magnetic field-free readout of the electronuclear spectrum for the H o 3 + ions in L i Y F 4 : H o 3 + . In particular, homogeneous and inhomogeneous contributions to the spectrum are readily separated. The experiment reveals previously unmeasured information regarding the hyperfine structure of the first excited state in the 5 I 8 manifold complementing the results reported in Phys. Rev. B 94, 205132 (2016)PRBMDO0163-182910.1103/PhysRevB.94.205132.

Dielectric Relaxation Mechanism in High-Pressure Synthesized BiCr0.5Mn0.5O3

The compound BiCr0.5Mn0.5O3, synthesized at high pressure and high temperature, shows a giant dielectric constant over a wide range of temperatures. Two relaxation processes are observed commencing around 200 K and 300 K. The low-temperature relaxation process is attributed to Maxwell–Wagner polarization at the grain boundary, whereas the second relaxation is attributed to the electrode polarization effect. Impedance spectroscopy reveals that the oxide is electrically inhomogeneous and dominant contribution arises from semiconducting grains and insulating grain boundary below room temperature. Above room temperature, the electrode polarization effect also contributes to the observed giant dielectric constant.

Reduced Inhomogeneous Broadening in Hexagonal Boron Nitride-Encapsulated MoTe2 Monolayers by Thermal Treatment

In this study, we systematically investigate the photoluminescence (PL) spectral changes caused by thermal treatment of hexagonal boron nitride (hBN)-encapsulated MoTe2 monolayers fabricated by standard dry transfer using polydimethylsiloxane. A strong trion peak is noticeable in the PL spectrum at 20 K of the hBN-encapsulated MoTe2 monolayers, indicating that the excess carriers in 1L-MoTe2 have a high density. Following thermal treatment, a strong and sharp neutral exciton peak appears in the PL spectra at low temperatures, owing to the reduction in both the trion peak intensity and inhomogeneous contribution to the exciton PL linewidth. For hBN-encapsulated MoTe2 monolayers, defect-bound exciton peak intensity is not enhanced even after the thermal treatment in contrast to SiO2-supported MoTe2 monolayers because the top hBN acts as a capping layer for the prevention of the desorption of Te atoms. It is demonstrated that the thermal treatment of hBN-encapsulated samples simultaneously enables the suppression of the crystal defect formation and the removal of the residues at the heterointerfaces, which lead to charge transfer to MoTe2.

Deep learning using a biophysical model for robust and accelerated reconstruction of quantitative, artifact-free and denoised images.

To introduce a novel deep learning method for Robust and Accelerated Reconstruction (RoAR) of quantitative and B0-inhomogeneity-corrected maps from multi-gradient recalled echo (mGRE) MRI data. RoAR trains a convolutional neural network (CNN) to generate quantitative maps free from field inhomogeneity artifacts by adopting a self-supervised learning strategy given (a) mGRE magnitude images, (b) the biophysical model describing mGRE signal decay, and (c) preliminary-evaluated F-function accounting for contribution of macroscopic B0 field inhomogeneities. Importantly, no ground-truth images are required and F-function is only needed during RoAR training but not application. We show that RoAR preserves all features of maps while offering significant improvements over existing methods in computation speed (seconds vs. hours) and reduced sensitivity to noise. Even for data with SNR = 5 RoAR produced maps with accuracy of 22% while voxel-wise analysis accuracy was 47%. For SNR = 10 the RoAR accuracy increased to 17% vs. 24% for direct voxel-wise analysis. RoAR is trained to recognize the macroscopic magnetic field inhomogeneities directly from the input magnitude-only mGRE data and eliminate their effect on measurements. RoAR training is based on the biophysical model and does not require ground-truth maps. Since RoAR utilizes signal information not just from individual voxels but also accounts for spatial patterns of the signals in the images, it reduces the sensitivity of maps to the noise in the data. These features plus high computational speed provide significant benefits for the potential usage of RoAR in clinical settings.