Energy Spectrum Research Articles

Black hole mass estimate in OJ 287 based on the bulk-motion comptonization model

ABSTRACT The multiwavelength outburst activity in the BL Lacertae source OJ 287 has sparked a lot of controversy about whether the source contains one or two black holes (BHs) and what characteristics of this BH binary would be. In this article, we present the results of analysis of the X-ray flaring activity of OJ 287 using the data of Swift/XRT observations. We discovered that the energy spectra in all spectral states can be adequately fit with the XSPEC bulk-motion Comptonization (BMC) model. As a result, we found that the X-ray photon index of the BMC model, $\Gamma$ correlates with the mass accretion rate, $\dot{M}$. We found the photon index $\Gamma$ to increase monotonically with accretion rate $\dot{M}$ from $\Gamma \sim 2$ in the intermediate state (IS) to $\Gamma \sim 2.5$ the high/soft state (HSS) with subsequent saturation at $\Gamma \sim$ 2.6 level at higher luminosities. This type of behaviour of the spectral index is remarkably similar to the pattern observed in a number of established stellar-mass BH candidates. Assuming the universality of the observed pattern of the correlation between the photon index and mass accretion rate and using the well-studied stellar-mass binaries GX 339–4 and XTE J1859–226 to calibrate the model, we estimate a BH mass $\sim 2\times 10^8$ solar masses, which likely pertains to the secondary component of the BH binary in OJ 287.

The Influence of Nano-Silicon Carbide on the Properties of Aluminum Alloy Under Salt Dry–Wet Alternations

In this study, the influence of silicon carbide on an aluminum alloy’s yield tensile strength, ultimate tensile strength, compressive strength, tensile toughness and impact toughness were investigated. Meanwhile, the aluminum alloy specimens were exposed to the dry–wet alternations with a 3% NaCl solution or 3% Na2SO4 solution. Scanning electron microscope (SEM) photos and scanning electron microscopy energy spectra (SEM-EDS) were obtained. The results indicate that the silicon carbide with a mass ratio of 0%~8% of the total mass of the aluminum alloy can increase the yield tensile strength, the ultimate tensile strength, and the compressive strength by rates of 0%~30.4%, 0%~14.1% and 0%~13.1%. However, when the mass ratio of the silicon carbide increased from 8% to 10%, the yield tensile strength, the ultimate tensile strength and the compressive strength decreased by rates of 0%~3.2%, 0%~2.6% and 0%~0.43%. The tensile toughness and the impact toughness decreased when silicon carbide was added, with reduction rates of 0%~15.3% and 0%~12.8%. The NaCl dry–wet alternations led to decreases in the yield tensile strength, the ultimate tensile strength, the compressive strength, the tensile toughness and the impact toughness by rates of 0%~7.3%, 0%~6.7%, 0%~13.9%, 0%~12.7% and 0%~11.2%, respectively. After the Na2SO4 dry–wet alternations, the corresponding decreasing rates were 0%~5.1%, 0%~5.4%, 0%~1.73%, 0%~11.4% and 0%~9.7%. The addition of silicon carbide resulted in a decrease in the effect on the mechanical strength by the NaCl and Na2SO4 dry–wet alternations. The elements carbon, oxygen, magnesium, aluminum and silicon were observed in the aluminum alloy. The structures of the aluminum alloy with 8% silicon carbide were the highest.

Doubly heavy tetraquark bound and resonant states

We calculate the energy spectrum of the S-wave doubly heavy tetraquark systems, including the QQ(′)q¯q¯, QQ(′)s¯q¯, and QQ(′)s¯s¯ (Q(′)=b, c and q=u, d) systems within the constituent quark model. We use the complex scaling method to obtain bound states and resonant states simultaneously, and the Gaussian expansion method to solve the complex-scaled four-body Schrödinger equation. With a novel definition of the root-mean-square radii, we are able to distinguish between meson molecules and compact tetraquark states. The compact tetraquarks are further classified into three different types with distinct spatial configurations: compact even tetraquarks, compact diquark-antidiquark tetraquarks, and compact diquark-centered tetraquarks. In the I(JP)=0(1+) QQq¯q¯ system, there exists the D*D molecular bound state with a binding energy of −14 MeV, which is the candidate for Tcc(3875)+. The shallow B¯*B¯ molecular bound state is the bottom analog of Tcc(3875)+. Moreover, we identify two resonant states near the D*D* and B¯*B¯* thresholds. In the JP=1+ bbq¯q¯(I=0) and bbs¯q¯ systems, we obtain deeply bound states with a compact diquark-centered tetraquark configuration and a dominant χ3¯c⊗3c component, along with resonant states with similar configurations as their radial excitations. These states are the QCD analog of the helium atom. We also obtain some other bound states and resonant states with “QCD hydrogen molecule” configurations. Moreover, we investigate the heavy quark mass dependence of the I(JP)=0(1+) QQq¯q¯ bound states. We strongly urge the experimental search for the predicted states. Published by the American Physical Society 2024

Entanglement Hamiltonian and effective temperature of non-Hermitian quantum spin ladders

Quantum entanglement plays a crucial role not only in understanding Hermitian many-body systems but also in offering valuable insights into non-Hermitian quantum systems. In this paper, we analytically investigate the entanglement Hamiltonian and entanglement energy spectrum of a non-Hermitian spin ladder using perturbation theory in the biorthogonal basis. Specifically, we examine the entanglement properties between coupled non-Hermitian quantum spin chains. In the strong coupling limit (J_\mathrm{rung}\gg1Jrung≫1), first-order perturbation theory reveals that the entanglement Hamiltonian closely resembles the single-chain Hamiltonian with renormalized coupling strengths, allowing for the definition of an ad hoc temperature. Our findings provide new insights into quantum entanglement in non-Hermitian systems and offer a foundation for developing novel approaches for studying finite temperature properties in non-Hermitian quantum many-body systems.

Quantitative multi-energy CT in oncology: State of the art and future directions

Multi-energy computed tomography (CT) involves acquisition of two or more CT measurements with distinct energy spectra. Using the differential attenuation of tissues and materials at different X-ray energies, multi-energy CT allows distinction of tissues and materials. Multi-energy technology encompasses different types of CT systems, such as dual-energy CT and photon-counting CT, that can use information from the energy and type of material present in acquired images to create multiple datasets. These scanners have overcome many of the limitations of conventional CT, making it possible to improve the diagnostic performance of CT and expand its use to new applications through better tissue characterization and multiple quantitative parameters. Quantitative imaging biomarkers based on multi-energy CT have enormous potential in oncologic imaging, from the diagnosis and characterization of tumor phenotypes to the evaluation of the response to treatment. Nevertheless, implementing these techniques in clinical practice remains challenging. This article reviews the basic principles underlying multi-energy CT and the most recent technical developments in these systems together with their advantages and limitations to establish the value of quantitative imaging derived from multi-energy CT in the field of oncology.

Short-term treatment response assessment in non-surgical treatment of advanced non-small cell lung cancer based on radiomics of dual-energy CT

PurposeTo build and evaluate a pre-treatment dual-energy CT(DECT)-based clinical-radiomics nomogram for individualized prediction of short-term treatment response to non-surgical treatment in advanced non-small cell lung cancer (NSCLC). MethodsPre-treatment DECT images were retrospectively collected from 98 pathologically confirmed NSCLC with clinical stage III or IV. Short-term treatment response was determined with follow-up CT of 4–6 courses of treatment. Quantitative radiomics metrics of the lesion were extracted from dual-energy mixed images at venous phase. Least absolute shrinkage and selection operator and correlation analysis were used to select the most relevant radiomics features. Radiomics model, clinical model and clinical-radiomics model were established by multivariate logistic regression. The model with the best prediction performance was visualized as a nomogram, and the consistency between the probability of the actual occurrence of the outcome and the probability predicted by the model was measured by calibration curves. ResultsClinical stage, difference in electron density in arteriovenous phase, difference in slope of energy spectrum in arteriovenous phase, and slope of energy spectrum in venous phase of the tumor were significant clinical predictors of therapy response (P < 0.05). The clinical-radiomics model showed a higher predictive capability (AUC: 0.87 and 0.85 in training and validation sets, respectively) than the radiomics models and the clinical model. The clinical-radiomics nomogram integrating the DECT radiomics signature with clinical stage and spectrum parameters showed good calibration and discrimination. ConclusionThe clinical-radiomics nomogram based on pre-treatment DECT showed good performance in predicting clinical response to non-surgical therapy in NSCLC.

Monochromatization of Electron Beams with Spatially and Temporally Modulated Optical Fields.

Inelastic interaction between coherent light with constant frequency and free electrons enables periodic phase modulation of electron wave packets leading to periodic sidebands in the electron energy spectra. In this Letter, we propose a generalization of the interaction by considering linearly chirped electron wave packets interacting with chirped optical fields. We theoretically demonstrate that when matching the chirp parameters of the electron and light waves, the interaction leads to partial monochromatization of the electron spectra in one of the energy sidebands. Depending on the coherence time of the electrons, the electron spectrum may be narrowed down by a factor of 5 times with 26% of the electron distribution in the monochromatized energy band. This approach will improve the spectral resolution and reduce color aberrations in ultrafast imaging experiments with free electrons.

Effect of an incoming Gaussian wave packet on underlying turbulence

We present a simulation-based study of the effect of a passing wave packet on underlying fully developed turbulence. We propose a novel wave-phase-resolved simulation method inspired by Helmholtz decomposition to directly couple the turbulence simulation with instantaneous wave orbital motions without wave-phase averaging. We also introduce a boundary condition treatment for the turbulence at the wave surface, which allows the turbulence simulation to be conducted in a rectangular domain while retaining the wave-phase effect. The results obtained from the proposed method reveal considerable variations in turbulence statistics, including the enstrophy and Reynolds normal stresses, during wave packet passage. Most changes occur rapidly when the narrow bandwidth around the wave packet core passes. Further analyses of the energy spectra indicate that the enhancement of turbulence occurs across a wide range of scales, with the near-surface small-scale motions experiencing the most significant intensification. Meanwhile, large-scale motions with scales comparable to the boundary layer depth are also enhanced. The mechanisms underlying the Reynolds normal stress variation at different length scales are related to the energy transfer from the wave orbital straining to turbulence through production, the pressure–strain effect, the pressure diffusion and the wave advection. By assessing the turbulence statistics and dynamics impacted by a wave packet in detail, this study provides an improved understanding of the response of a developed turbulent flow to a transient wave field. The proposed simulation method also proves to be a promising phase-resolved approach for efficiently modelling the wave effect on turbulence.

Finite beaming effect on QED cascades

The quantum electrodynamic (QED) theory predicts the photon emission and pair creation involved in QED cascades occur mainly in a forward cone with finite angular spread Δθ∼1/γi along the momenta of incoming particles. This finite beaming effect has been assumed to be negligible because of the particles' ultra-relativistic Lorentz factor γi≫1 in laser-driven QED cascades. We develop an energy- and angularly resolved particle-tracking code, resolving both the energy spectra and the momentum profile of the outgoing particles in each QED event, which improves substantially the agreement between the simulation and exact QED results. We investigate QED cascades driven by two counter-propagating circularly polarized laser pulses, and show that the narrow beaming could be accumulated to effectively suppress the long-term growth of cascades, even though it can hardly affect the early formation of cascades. For QED cascades longer than 10 laser cycles, the finite beaming effect could decrease the final pair yield, especially at ultrahigh intensities ξ>600, by more than 10%.

Grain boundary segregation spectrum in basal-textured Mg alloys: From solute decoration to structural transition

Mg alloys are promising lightweight structural materials due to their low density and excellent mechanical properties. However, their limited formability and ductility necessitate improvements in these properties, specifically through texture modification via grain boundary segregation. While significant efforts have been made, the segregation behavior in Mg polycrystals, particularly with basal texture, remains largely unexplored. In this study, we performed atomistic simulations to investigate grain boundary segregation in dilute and concentrated solid solution Mg–Al alloys. We computed the segregation energy spectrum of basal-textured Mg polycrystals, highlighting the contribution from specific grain boundary sites, such as junctions, and identified a newly discovered bimodal distribution which is distinct compared to the conventional skew-normal distribution found in randomly-oriented polycrystals. Using a hybrid molecular dynamics/Monte Carlo approach, we simulated segregation behavior at finite temperatures, identifying grain boundary structural transitions, particularly the varied fraction and morphology of topologically close-packed grain boundary phases when changing thermodynamic variables. The outcomes of this study offer crucial insights into basal-textured grain boundary segregation and phase formation, which can be extended to other relevant Mg alloys containing topologically close-packed intermetallics.

Strong CP problem in the quantum rotor

Recent studies have claimed that the strong CP problem does not occur in QCD, proposing a new order of limits in volume and topological sectors when studying observables on the lattice. In order to shed light on this issue, we study the effect of the topological θ-term on a simple quantum mechanical rotor that allows a lattice description. The topological susceptibility and the θ-dependence of the energy spectrum are both computed using local lattice correlation functions. The sign problem is overcome by considering Taylor expansions in θ, exploiting automatic differentiation methods for Monte Carlo processes. Our findings confirm the conventional wisdom on the strong CP problem. Published by the American Physical Society 2024

Theoretical Study of Position-Dependent Mass Particle in Cosmic String Space-Time and External Magnetic Field

In this work, we discuss the case of a non-relativistic quantum particle in the cosmic string space-time under the influence of the presence of external magnetic and exponential potential. It’s shown with the help of the Laplace transform method the second-order differential equation of the Schrodinger equation is solvable where it is reduced to a first-order differential equation. We obtain the eigenfunction and the non-relativistic energy spectrum. In addition, these results may be useful in the future study of thermodynamic, optic, and magnetic properties of the atomic interaction of a system particle. Keywords: Schrodinger equation; Laplace transform method; Position dependent mass; External magnetic field; Cosmic string

The impact of electrical stimulation on NaCl diffusion in tenderloin and the quality of dry-cured loin during the marination process

The effects of electrical stimulation (ES) during the post-processing stage on NaCl diffusion, microstructure, and overall quality in the dry curing of pork tenderloin were investigated. ES treatment significantly increased the salt content in pork tenderloin, with the A2ES group (ES applied after 2 h of curing) showing a 28.32 % increase compared to the control group. Energy spectrum analysis revealed that NaCl distribution in the meat tissue was most concentrated following ES treatment. Binarized images of NaCl permeation in pork loin clearly demonstrated that ES enhanced NaCl permeation. Additionally, microscopic analysis showed that ES caused cell disintegration, and the combined effect of ES and NaCl damaged muscle tissue. The results indicate that ES enhanced NaCl diffusion and shortened the curing time, while improving meat tenderness and reducing bitter and astringent flavors. This study offers new insights and techniques to accelerate the marination process of meat products.

Thermal chemistry of Anti-de-Sitter black holes in Kalb-Ramond gravity

In this paper, we investigate the thermodynamic properties and emission energy of Anti-de-Sitter (AdS) black holes within the framework of Kalb-Ramond gravity. By analyzing the modified Einstein equations with the inclusion of the antisymmetric Kalb-Ramond tensor field, we explore the changes in key thermodynamic quantities such as temperature, entropy, and specific heat, alongside the emission energy spectrum associated with Hawking radiation. The study reveals novel thermal behaviors and energy emission patterns compared to standard AdS black holes, particularly highlighting the influence of the Kalb-Ramond field on black hole stability and phase transitions. Furthermore, we examine the role of the Kalb-Ramond field in modifying the emission energy. Our findings provide deeper insights into black hole thermodynamics, the emission process, and the broader role of antisymmetric fields in gravitational physics. Different paths for test particles near black holes are determined by their distance from the innermost stable circular orbit, which plays a crucial role in this study. The unique behavior of particles impacted by mass and rotational momentum is highlighted by the fact that particles within the innermost stable circular orbits tend to converge toward the singularity, but particles outside tend to diverge toward infinity.

Spectral CT-based nomogram for preoperative prediction of Lauren classification in locally advanced gastric cancer: a prospective study.

To develop a nomogram based on clinical features and spectral quantitative parameters to preoperatively predict the Lauren classification for locally advanced gastric cancer (LAGC). Patients diagnosed with LAGC by postoperative pathology who underwent abdominal triple-phase enhanced spectral computed tomography (CT) were prospectively enrolled in this study between June 2023 and December 2023. All the patients were categorized into intestinal- and diffuse-type groups according to the Lauren classification. Traditional characteristics, including demographic information, serum tumor markers, gastroscopic pathology, and image semantic features, were collected. Spectral quantitative parameters, including iodine concentration (IC), effective atomic number (Zeff), and slope of the energy spectrum curve from 40 keV to 70 keV (λ), were measured three times for each patient by two blinded radiologists in arterial/venous/delayed phases (AP/VP/DP). Differences in traditional features and spectral quantitative parameters between the two groups were compared using univariable analysis. Independent predictors of the Lauren classification of LAGC were screened using multivariable logistic regression analysis. Receiver operating characteristic (ROC) curve analysis was used to assess the discriminating capability. Ultimately, the nomogram, including clinical features and spectral CT quantitative parameters, was developed. Gender, nIC in AP (APnIC), and λ in DP (λd) were independent predictors for Lauren classification. The nomogram based on these indicators produced the best performance with an area under the curve of 0.841 (95% confidence interval: 0.749-0.932), specificity of 85.3%, accuracy of 76.4%, and sensitivity of 68.4%. The nomogram based on clinical features and spectral CT quantitative parameters exhibits great potential in the preoperative and non-invasive assessment of Lauren classification for LAGC. Question Can the proposed nomogram, integrating clinical features and spectral quantitative parameters, preoperatively predict the Lauren classification in locally advanced gastric cancer (LAGC)? Findings The nomogram, based on gender, arterial phase normalized iodine concentration, and slope of the energy spectrum curve in the delayed phase showed satisfactory predictive ability. Clinical relevance The established nomogram could contribute to guiding individualized treatment strategies and risk stratification in patients by predicting the Lauren classification for LAGC before surgery.

Exploring wobbling motion in triaxial even-even nuclei

The potential presence of wobbling motions in even-even nuclei 112Ru, 114Pd, 150Nd, and 188Os are explored by the five-dimensional collective Hamiltonian based on the relativistic density functional theory (5DCH-RDFT). The theoretical results successfully reproduce experimental energy spectra and electromagnetic transition probabilities. Analyses of the potential energy surfaces and probability density distributions in the (β,γ) deformation plane as well as the quadrupole asymmetry parameter 〈cos⁡3δ〉 reveal that 150Nd shows near-axial symmetry in contrast to the triaxial deformation in 112Ru, 114Pd, and 188Os. Additionally, spin coherent state (SCS) map is introduced for the first time to the 5DCH framework to visualize the geometry of angular momentum. It is revealed that the wobbling mode, characterized by oscillations of total angular momentum J about the medium axis, is present in 112Ru but absent in 150Nd.

On the two-dimensional harmonic oscillator with an electric field confined to a circular box

Abstract We revisit the quantum-mechanical two-dimensional harmonic oscillator with an electric field confined to a circular box of impenetrable walls. In order to obtain the energy spectrum we resort to the Rayleigh-Ritz method with polynomial and Gaussian basis sets. We compare present results with those derived recently by other authors. We discuss the limits of large and small box radius and also do some calculations with perturbation theory.&amp;#xD;

Spectral Signatures of Nontrivial Topology in a Superconducting Circuit

Topology, like symmetry, is a fundamental concept in understanding general properties of physical systems. In condensed matter, nontrivial topology may manifest itself as singular features in the energy spectrum or the quantization of electrical properties such as conductance and magnetic flux. Using microwave spectroscopy, we determine that a superconducting circuit with three Josephson tunnel junctions in parallel can possess degeneracies indicative of nontrivial topology. We identify three topological invariants, one of which is related to a hidden quantum mechanical supersymmetry. Measurements show that devices fabricated in different topological regimes fall on a simple phase diagram, which should be robust to junction imperfections and geometric inductance. Josephson tunnel junction circuits, which are readily fabricated with conventional microlithography techniques, allow access to a wide range of topological systems that may have no condensed matter analog. Notable spectral features of these circuits, such as degeneracies and flat bands, may find use in quantum information, sensing, and metrology. Published by the American Physical Society 2024

Sources and Radiations of the Fermi Bubbles

Two enigmatic gamma-ray features in the galactic central region, known as Fermi Bubbles (FBs), were found from Fermi-LAT data. An energy release, (e.g., by tidal disruption events in the Galactic Center, GC), generates a cavity with a shock that expands into the local ambient medium of the galactic halo. A decade or so ago, a phenomenological model of the FBs was suggested as a result of routine star disruptions by the supermassive black hole in the GC which might provide enough energy for large-scale structures, like the FBs. In 2020, analytical and numerical models of the FBs as a process of routine tidal disruption of stars near the GC were developed; these disruption events can provide enough cumulative energy to form and maintain large-scale structures like the FBs. The disruption events are expected to be 10−4∼10−5yr−1, providing an average power of energy release from the GC into the halo of E˙∼3×1041 erg s−1, which is needed to support the FBs. Analysis of the evolution of superbubbles in exponentially stratified disks concluded that the FB envelope would be destroyed by the Rayleigh–Taylor (RT) instabilities at late stages. The shell is composed of swept-up gas of the bubble, whose thickness is much thinner in comparison to the size of the envelope. We assume that hydrodynamic turbulence is excited in the FB envelope by the RT instability. In this case, the universal energy spectrum of turbulence may be developed in the inertial range of wavenumbers of fluctuations (the Kolmogorov–Obukhov spectrum). From our model we suppose the power of the FBs is transformed partly into the energy of hydrodynamic turbulence in the envelope. If so, hydrodynamic turbulence may generate MHD fluctuations, which accelerate cosmic rays there and generate gamma-ray and radio emission from the FBs. We hope that this model may interpret the observed nonthermal emission from the bubbles.

Energy characteristics of the gridless ion sources beams

One of the most commonly used tools in ion-plasma technology is the End Hall ion source, which is used, in particular, for etching and other processes. The ability to operate on almost any gas, a highly divergent beam and the generated ions energy range up to several hundred electronvolts determine the wide possibilities of using End Hall ion sources in science and production. There are two main design schemes of such sources which are most actively used – with a floating and with an anode potential of the discharge chamber rear wall. The ion beam energy characteristics of the sources with a floating potential of the rear wall have been extensively studied by various research teams, but there is currently no comparable data available for sources with an anode potential, making it difficult to develop processes based on these ion sources. This study aims to investigate the energy characteristics of ions emitted from End Hall sources following these two design approaches. The ion beams were examined via a retarding potential analyzer. Measurements were conducted on argon at various discharge voltage and current settings for each source. One design included a floating potential of the discharge chamber rear wall, whereas the other design had an anode potential. The geometrical dimensions of the discharge chambers and the magnetic field intensities were identical for both configurations tested. Based on the ion beam retarding curves, corresponding ion energy distributions were determined. It was observed that for End Hall source with an anode potential of the discharge chamber rear wall an approximately continuous spectrum of ion energies was typical, whereas there was a clearly expressed peak in the energy distribution of the traditional configuration ion source beam. The mean ion energy in beam of the source with an anode potential of the discharge chamber rear wall was lower than that of the source with a floating potential, as confirmed by lower etch rates observed during control sputtering of stainless steel samples. These results can be used to develop technological procedures utilizing End Hall ion sources designed according to different configurations.