Line Profiles Research Articles

Method to determine the optimal impedance profile of nonuniform transmission lines used for pulsed power accelerators

Nonuniform transmission lines (NTLs) are widely used in pulsed power accelerators because they provide an efficient way to achieve impedance matching and pulse shaping. Since designing and constructing these accelerators typically demands substantial effort, finding the optimal impedance profile to maximize the power transmission efficiencies of the NTLs is important. In this paper, a convenient numerical method to determine the optimal impedance profile is proposed. First, the output of the NTL with arbitrary parameters is theoretically analyzed under arbitrary input conditions. It was found that only four factors affect the power transmission efficiency: the ratio of output impedance to input impedance, the ratio of input pulse width to the NTL’s one-way transit time, the normalized impedance profile, and the normalized input pulse. Based on these findings, a method designed to minimize the reflected component within the working frequency range is proposed. Using this method, an impedance profile demonstrating superior power transmission efficiency compared to the traditional exponential profile is identified. This work can provide a rapid and effective method to determine the impedance profile of the NTL, undoubtedly benefiting the design process of pulsed power accelerators. Published by the American Physical Society 2024

Dynamic protein-protein interactions of KCNQ1 and KCNE1 measured by EPR line shape analysis

KCNQ1, also known as Kv7.1, is a voltage gated potassium channel that associates with the KCNE protein family. Mutations in this protein has been found to cause a variety of diseases including Long QT syndrome, a type of cardiac arrhythmia where the QT interval observed on an electrocardiogram is longer than normal. This condition is often aggravated during strenuous exercise and can cause fainting spells or sudden death. KCNE1 is an ancillary protein that interacts with KCNQ1 in the membrane at varying molar ratios. This interaction allows for the flow of potassium ions to be modulated to facilitate repolarization of the heart. The interaction between these two proteins has been studied previously with cysteine crosslinking and electrophysiology. In this study, electron paramagnetic resonance (EPR) spectroscopy line shape analysis in tandem with site directed spin labeling (SDSL) was used to observe changes in side chain dynamics as KCNE1 interacts with KCNQ1. KCNE1 was labeled at different sites that were found to interact with KCNQ1 based on previous literature, along with sites outside of that range as a control. Once labeled KCNE1 was incorporated into vesicles, KCNQ1 (helices S1-S6) was titrated into the vesicles. The line shape differences observed upon addition of KCNQ1 are indicative of an interaction between the two proteins. This method provides a first look at the interactions between KCNE1 and KCNQ1 from a dynamics perspective using the full transmembrane portion of KCNQ1.

An Hi-absorption-selected Cold Rotating Disk Galaxy at z ≈ 2.193

We have used the Atacama Large Millimeter/submillimeter Array to map CO(3–2) emission from a galaxy, DLA-B1228g, associated with the high-metallicity damped Lyα absorber at z ≈ 2.1929 toward the QSO PKS B1228–113. At an angular resolution of ≈0.″32 × 0.″24, DLA-B1228g shows extended CO(3–2) emission with a deconvolved size of ≈0.″78 × 0.″18, i.e., a spatial extent of ≈6.4 kpc. We detect extended stellar emission from DLA-B1228g in a Hubble Space Telescope Wide Field Camera 3 F160W image and find that Hα emission is detected in a Very Large Telescope SINFONI image from only one side of the galaxy. While the clumpy nature of the F160W emission and the offset between the kinematic and physical centers of the CO(3–2) emission are consistent with a merger scenario, this appears unlikely due to the lack of strong Hα emission, the symmetric double-peaked CO(3–2) line profile, the high molecular gas depletion timescale, and the similar velocity dispersions in the two halves of the CO(3–2) image. Kinematic modeling reveals that the CO(3–2) emission is consistent with arising from an axisymmetric rotating disk with an exponential profile, a rotation velocity of v rot = 328 ± 7 km s−1, and a velocity dispersion of σ v = 62 ± 7 km s−1. The high value of the ratio v rot/σ v , ≈5.3, implies that DLA-B1228g is a rotation-dominated cold disk galaxy, the second case of a high-z Hi-absorption-selected galaxy identified with a cold rotating disk. We obtain a dynamical mass of M dyn = (1.5 ± 0.1) × 1011 M ⊙, similar to the molecular gas mass of ≈1011 M ⊙ inferred from earlier CO(1–0) studies; this implies that the galaxy is baryon-dominated in its inner regions.

Integrated analysis of yield response and early stage biochemical, molecular, and gene expression profiles of pre-breeding rice lines under water deficit stress

Breeding high yielding water-deficit tolerant rice is considered a primary goal for achieving the objectives of the sustainable development goals, 2030. However, evaluating the performance of the pre-breeding-promising parental-lines for water deficit tolerance prior to their incorporation in the breeding program is crucial for the success of the breeding programs. The aim of the current investigation is to assess the performance of a set of pre-breeding lines compared with their parents. To achieve this goal a set of 7 pre-breeding rice lines along with their parents (5 genotypes) were field evaluated under well-irrigated and water-stress conditions. Water stress was applied by flush irrigation every 12 days without keeping standing water after irrigation. Based on the field evaluation results, a pre-breeding line was selected to conduct physiological and expression analysis of drought related genes at the green house. Furthermore, a greenhouse trial was conducted in pots, where the genotypes were grown under well and stress irrigation conditions at seedling stage for physiological analysis and expression profiling of the genotypes. Results indicated that the pre-breeding lines which were high yielding under water shortage stress showed low drought susceptibility index. Those lines exhibited high proline, SOD, TSS content along with low levels of MDA content in their leaves. Moreover, the genotypes grain yield positively correlated with proline, SOD, TSS content in their leaves. The SSR markers RM22, RM525, RM324 and RM3805 were able to discriminate the tolerant parents from the sensitive one. Expression levels of the tested drought responsive genes revealed the upregulation of OsLEA3, OsAPX2, OsNAC1, OSDREB2A, OsDREB1C, OsZIP23, OsP5CS, OsAHL1 and OsCATA genes in response to water deficit stress as compared to their expression under normal irrigated condition. Taken together among the tested pre-breeding lines the RBL112 pre-breeding line is high yielding under water-deficit and could be used as donor for high yielding genes in the breeding for water deficit resistance. This investigation withdraws attention to evaluate the promising pre-breeding lines before their incorporation in the water deficit stress breeding program.

X-Shooting ULLYSES: Massive stars at low metallicity

Context. The winds of massive stars have a significant impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed v∞, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UV spectroscopic survey with the Hubble Space Telescope, we have the opportunity to quantify the wind speeds of massive stars at sub-solar metallicity (in the Large and Small Magellanic Clouds, 0.5 Z⊙ and 0.2 Z⊙, respectively) at an unprecedented scale. Aims. We empirically quantify the wind speeds of a large sample of OB stars, including supergiants, giants, and dwarfs at sub-solar metallicity. Using these measurements, we investigate trends of v∞ with a number of fundamental stellar parameters, namely effective temperature (Teff), metallicity (Z), and surface escape velocity vesc. Methods. We empirically determined v∞ for a sample of 149 OB stars in the Magellanic Clouds either by directly measuring the maximum velocity shift of the absorption component of the C IV λλ1548–1550 line profile, or by fitting synthetic spectra produced using the Sobolev with exact integration method. Stellar parameters were either collected from the literature, obtained using spectral-type calibrations, or predicted from evolutionary models. Results. We find strong trends of v∞ with Teff and vesc when the wind is strong enough to cause a saturated P Cygni profile in C IV λλ1548–1550. We find evidence for a metallicity dependence on the terminal wind speed v∞ ∝ Z0.22±0.03 when we compared our results to previous Galactic studies. Conclusions. Our results suggest that Teff rather than vesc should be used as a straightforward empirical prediction of v∞ and that the observed Z dependence is steeper than suggested by earlier works.

On the Doublet Flux Ratio of Mg ii Resonance Lines in and Around Galaxies

Observations of metallic doublet emission lines, particularly Mg ii λ λ2796, 2803, provide crucial information for understanding galaxies and their circumgalactic medium. This study explores the effects of resonant scattering on the Mg ii doublet lines and the stellar continuum in spherical and cylindrical geometries. Our findings show that under certain circumstances, resonance scattering can cause an increase in the doublet flux ratio and the escaping flux of the lines beyond what is expected in optically thin spherical media. As expected, the doublet ratio is consistently lower than the intrinsic ratio when the scattering medium is spherically symmetric and dusty. However, if the scattering medium has a disk shape, such as face-on disk galaxies, and is viewed face-on, the doublet ratio is predicted to be higher than 2. It is also shown that doublet ratios as low as those observed in compact star-forming galaxies cannot be explained solely by pure dust attenuation of intrinsic Mg ii emission lines in spherical models unless dust opacity deviates markedly from that expected based on the dust-to-Mg+ gas ratio of our Galaxy. The importance of the continuum-pumped emission lines and expanding media is discussed to understand observational aspects, including doublet flux ratios, which can be lower than 1.5 or higher than 2, as well as symmetric or asymmetric line profiles. It is also discussed that the diffuse warm neutral medium may be an important source of Mg ii emission. These results provide insight into the complexity of the shape and orientation of distant, spatially unresolved galaxies.

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Context. We explore the chemistry of the most abundant C-, O-, S-, and N-bearing species in molecular clouds, in the context of the IRAM 30 m Large Programme Gas phase Elemental abundances in Molecular Clouds (GEMS). Thus far, we have studied the impact of the variations in the temperature, density, cosmic-ray ionisation rate, and incident UV field in a set of abundant molecular species. In addition, the observed molecular abundances might be affected by turbulence which needs to be accounted for in order to have a more accurate description of the chemistry of interstellar filaments. Aims. In this work, we aim to assess the limitations introduced in the observational works when a uniform density is assumed along the line of sight for fitting the observations, developing a very simple numerical model of a turbulent box. We searched for any observational imprints that might provide useful information on the turbulent state of the cloud based on kinematical or chemical tracers. Methods. We performed a magnetohydrodynamical (MHD) simulation in order to reproduce the turbulent steady state of a turbulent box with properties typical of a molecular filament before collapse. We post-processed the results of the MHD simulation with a chemical code to predict molecular abundances, and then post-processed this cube with a radiative transfer code to create synthetic emission maps for a series of rotational transitions observed during the GEMS project. Results. From the kinematical point of view, we find that the relative alignment between the observer and the mean magnetic field direction affect the observed line profiles, obtaining larger line widths for the case when the line of sight is perpendicular to the magnetic field. These differences might be detectable even after convolution with the IRAM 30 m efficiency for a nearby molecular cloud. From the chemical point of view, we find that turbulence produces variations for the predicted abundances, but they are more or less critical depending on the chosen transition and the chemical age. When compared to real observations, the results from the turbulent simulation provides a better fit than when assuming a uniform gas distribution along the line of sight. Conclusions. In the view of our results, we conclude that taking into account turbulence when fitting observations might significantly improve the agreement with model predictions. This is especially important for sulfur bearing species which are very sensitive to the variations of density produced by turbulence at early times (0.1 Myr). The abundance of CO is also quite sensitive to turbulence when considering the evolution beyond a few 0.1 Myr.

An Expanding Accretion Disk and a Warm Disk Wind as Seen in the Spectral Evolution of HBC 722

We present a comprehensive analysis of the post-outburst evolution of the FU Ori object HBC 722 in optical/near-infrared (NIR) photometry and spectroscopy. Using a modified viscous accretion disk model, we fit the outburst epoch spectral energy distribution to determine the physical parameters of the disk, including Ṁacc=10−4.0M⊙ yr−1, R inner = 3.65 R ⊙, i = 79°, and a maximum disk temperature of Tmax=5700 K. We then use a decade of optical/NIR spectra to demonstrate a changing accretion rate drives the visible-range photometric variation, while the NIR shows the outer radius of the active accretion disk expands outward as the outburst progresses. We also identify the major components of the disk system: a plane-parallel disk atmosphere in Keplerian rotation and a two-part warm disk wind that is collimated near the star and wide-angle at larger radii. The wind is traced by classic wind lines, and appears as a narrow, low-velocity, deep absorption component in several atomic lines spanning the visible spectrum and in the CO 2.29 μm band. We compare the wind lines to those computed from wind models for other FU Ori systems and rapidly accreting young stellar disks and find a 4000–6000 K wind can explain the observed line profiles. Fitting the progenitor spectrum, we find M * = 0.2 M ⊙ and Ṁprogenitor=7.8×10−8M⊙yr−1 . Finally, we discuss HBC 722 relative to V960 Mon, another FU Ori object we have previously studied in detail.

Spectral analysis of three hot subdwarf stars: EC 11481-2303, Feige 110, and PG 0909+276

Context. For the precise spectral analysis of hot stars, advanced stellar-atmosphere models that consider deviations from the local thermodynamic equilibrium are mandatory. This requires accurate atomic data to calculate all transition rates and occupation numbers for atomic levels in the considered model atoms, not only for a few prominent lines exhibited in an observation. The critical evaluation of atomic data is a challenge because it requires precise laboratory measurements. Ultraviolet spectroscopy of hot stars with high resolving power provide such “laboratory” spectra. Aims. We compare observed, isolated lines of the iron group (here calcium to nickel) with our synthetic line profiles to judge the accuracy of the respective oscillator strengths. This will verify them or yield individual correction values to improve the spectral analysis, that is the determination of, for example, effective temperature (Teff) and abundances. Methods. To minimize the error propagation from uncertainties in Teff, surface gravity (𝑔), and abundance determination, we start with a precise reanalysis of three hot subdwarf stars, namely EC 11481-2303, Feige 110, and PG0909+276. Then, we measure the abundances of the iron-group elements individually. Based on identified, isolated lines of these elements, we compare observation and models to measure their deviation in strength (equivalent width). Results. For EC 11481–2303 and Feige 110, we confirmed the previously determined Teff and log 𝑔 values within their error limits. For all three stars, we fine-tuned all metal abundances to achieve the best reproduction of the observation. For more than 450 isolated absorption lines of the iron group, we compared modeled and observed line strengths. Considering the uncertainty of the analysis and evaluation procedure, an upper limit for the uncertainty of the underlying atomic data was established. Conclusions. We selected strong, reliable isolated absorption lines, which we recommend to use as reference lines for abundance determinations in related objects.

Final Moments. II. Observational Properties and Physical Modeling of Circumstellar-material-interacting Type II Supernovae

We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time (δ t < 2 days) spectra show transient, narrow emission lines from shock ionization of confined (r < 1015 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i, He i/ii, C iv, and N iii/iv/v from the CSM persist on a characteristic timescale (t IIn) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early time IIn-like features in addition to 35 “comparison” SNe with no evidence of early time IIn-like features, all with ultraviolet observations. The total sample includes 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both t IIn and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through the matching of peak multiband absolute magnitudes, rise times, t IIn, and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: tIIn≈3.8[Ṁ/ (0.01 M ⊙ yr−1)] days.

Multi-Fano resonances by TCS and resonance-enhanced TES in hybrid photonic crystals for ultracompact sensing

This work introduces a novel hybrid photonic crystal (PC) architecture exploiting topologically multi-Fano resonances employing an inverted π-shape structure filled with a nontrivial PC flanked by M−shaped trivial PCs for ultracompact and high-sensitivity sensing, harnessing their immense potential for miniaturized sensing applications. Topological corner state (TCS) is formed in the structure. Moreover, a waveguide-branch resonator or a resonant ring for the topological edge state (TES) mode is formed to increase the Fano resonance. We demonstrate the existence of engineered quasi-bound multi-Fano resonances within this structure, exhibiting tunable quality factors exceeding 108 (ultrahigh Q) and a remarkable figure of merit (FOM), reaching 2.6×107RIU-1. By precisely controlling the nontrivial PC dimensions, we achieve exquisite control over the resonance’s Q factor and spectral line shape, revealing characteristics of quasi-bound states in the continuum (BICs). This hybrid architecture exhibits exceptional sensitivity to refractive index changes, with tunability ranging from 320 to 392 nm/RIU. Our work paves the way for a new paradigm in sensing, enabling the development of ultracompact on-chip nanophotonic devices with unprecedented sensitivity and control.

Calculating absorption and fluorescence spectra for chromophores in solution with ensemble Franck-Condon methods.

Accurately modeling absorption and fluorescence spectra for molecules in solution poses a challenge due to the need to incorporate both vibronic and environmental effects, as well as the necessity of accurate excited state electronic structure calculations. Nuclear ensemble approaches capture explicit environmental effects, Franck-Condon methods capture vibronic effects, and recently introduced ensemble-Franck-Condon approaches combine the advantages of both methods. In this study, we present and analyze simulated absorption and fluorescence spectra generated with combined ensemble-Franck-Condon approaches for three chromophore-solvent systems and compare them to standard ensemble and Franck-Condon spectra, as well as to the experiment. Employing configurations obtained from ground and excited state abinitio molecular dynamics, three combined ensemble-Franck-Condon approaches are directly compared to each other to assess the accuracy and relative computational time. We find that the approach employing an average finite-temperature Franck-Condon line shape generates spectra nearly identical to the direct summation of an ensemble of Franck-Condon spectra at one-fourth of the computational cost. We analyze how the spectral simulation method, as well as the level of electronic structure theory, affects spectral line shapes and associated Stokes shifts for 7-nitrobenz-2-oxa-1,3-diazol-4-yl and Nile red in dimethyl sulfoxide and 7-methoxy coumarin-4-acetic acid in methanol. For the first time, our studies show the capability of combined ensemble-Franck-Condon methods for both absorption and fluorescence spectroscopy and provide a powerful tool for simulating linear optical spectra.

Magnetic Fields beneath Active Region Coronal Loops

We examine the hypothesis that multipolar magnetic fields advected by photospheric granules can contribute to heating the active chromosphere and corona. On 2020 September 28 the Gregor Infrared Spectrograph (GRIS) and HiFI+ instruments at the GREGOR telescope obtained data of NOAA 12773. We analyze Stokes profiles of spectral lines of Si i and He i, to study magnetic fields from the photosphere to the upper chromosphere. Magnetogram and EUV data from the Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly instruments on the Solar Dynamics Observatory spacecraft are coaligned and studied in relation to the GRIS data. At coronal loop footpoints, minor polarity fields comprise just 0.2% and 0.02% of the flux measured over the 40″ × 60″ area observed in the photosphere and upper chromosphere, centered 320″ from the disk center. Significantly, the minority fields are situated ≳12″ from bright footpoints. We use physical arguments to show that any unresolved minority flux cannot reach coronal footpoints adjacent to the upper chromosphere. Even if it did, the most optimistic estimate of the energy released through chromospheric reconnection is barely sufficient to account for the coronal energy losses. Further, dynamical changes accompanying reconnection between uni- and multipolar fields are seen neither in the He i data nor in narrowband movies of the Hα line core. We conclude that the hypothesis must be rejected. Bright chromospheric, transition region, and coronal loop plasmas must be heated by mechanisms involving unipolar fields.

The Expression Profiles of lncRNAs Are Associated with Neoadjuvant Chemotherapy Resistance in Locally Advanced, Luminal B-Type Breast Cancer.

lncRNAs are noncoding transcripts with tissue and cancer specificity. Particularly, in breast cancer, lncRNAs exhibit subtype-specific expression; they are particularly upregulated in luminal tumors. However, no gene signature-based laboratory tests have been developed for luminal breast cancer identification or the differential diagnosis of luminal tumors, since no luminal A- or B-specific genes have been identified. Particularly, luminal B patients are of clinical interest, since they have the most variable response to neoadjuvant treatment; thus, it is necessary to develop diagnostic and predictive biomarkers for these patients to optimize treatment decision-making and improve treatment quality. In this study, we analyzed the lncRNA expression profiles of breast cancer cell lines and patient tumor samples from RNA-Seq data to identify an lncRNA signature specific for luminal phenotypes. We identified an lncRNA signature consisting of LINC01016, GATA3-AS1, MAPT-IT1, and DSCAM-AS1 that exhibits luminal subtype-specific expression; among these lncRNAs, GATA3-AS1 is associated with the presence of residual disease (Wilcoxon test, p < 0.05), which is related to neoadjuvant chemotherapy resistance in luminal B breast cancer patients. Furthermore, analysis of GATA3-AS1 expression using RNA in situ hybridization (RNA ISH) demonstrated that this lncRNA is detectable in histological slides. Similar to estrogen receptors and Ki67, both commonly detected biomarkers, GATA3-AS1 proves to be a suitable predictive biomarker for clinical application in breast cancer laboratory tests.

Abundances of neutron-capture elements in selected solar-type stars

The primary objective of this study is to accurately determine the abundances of Cu, Sr, Y, Zr, Ba, La, and Ce in selected solar-type stars. This will allow us to establish observational abundance--metallicity and abundance--age relations and to explore the reasons for the excess of Ba compared to other $s$-elements in younger solar-type stars. The chosen $s$-process elements are critical diagnostics for understanding the chemical evolution of our Galaxy. We analysed HARPS spectra with a high resolution ($R$ = 115\,000) and high signal-to-noise ratio (close to 100) of main-sequence solar-type FGK stars with metallicities from $-0.15$ to +0.35 dex and ages from 2 to 14 Gyr using one-dimensional (1D) local thermodynamic equilibrium (LTE) synthesis and MARCS atmospheric models. In the procedure of fitting synthetic to observed line profiles, the free parameters included abundance and microturbulent and macroturbulent velocity. The macroturbulent velocity can substantially compensate for non-local thermodynamic equilibrium (NLTE) effects in the line core. The resulting elemental abundance X/H increases with metallicity and age for solar-type stars. The ratio of the abundances of $s$-process elements s/Fe increases with decreasing metallicity and age, while the Cu/Fe ratio increases with both metallicity and age. These observed trends agree well with published observational data and with predictions from Galactic chemical evolution (GCE) models. A small Ba/Fe enhancement of 0.08 ± 0.08 dex has been detected in seven younger stars with an average age of $2.8 0.6$ Gyr. Compared to the abundances of other $s$-process elements Ba/Fe is 0.07 and 0.08 dex higher than La and Ce on average, respectively. Furthermore, we find that the Ba/Fe ratio increases with increasing chromospheric activity. The average Ba/Fe for the three most active stars is $0.15 0.10$ dex higher than that of the other stars. Chromospheric activity, characterised by stronger magnetic fields found in active regions such as pores, spots, plages, and networks, can significantly alter the physical conditions in the formation layers of the Ba lines. Our primary conclusion is that to account for the observed excess of Ba/Fe abundance in younger stars, it is essential to use more complex atmospheric models that incorporate magnetic structures.

Full quantum calculations of the line shape for H2O perturbed by Ar at temperatures from 20 to 300 K.

This work theoretically studied the spectral line shape of H2O perturbed by Ar in the temperature range of 20-300K for the pure rotational lines below 360cm-1, as well as three lines (31, 2 ← 44, 1, 54, 2 ← 41, 3, and 73, 5 ← 60, 6) in the v2 band. In order to perform precise dynamical calculations at low collision energies, a full-dimensional long-range potential energy surface was constructed for the H2O-Ar system for the first time to correct the long range of our newly developed intermolecular potential energy surface. Subsequently, the six line-shape parameters (pressure-broadening and -shifting parameters, their speed dependencies, and the complex Dicke parameters) were determined from the generalized spectroscopic cross section by the full quantum time-independent close-coupling approach on this new potential energy surface. Our theoretical results are in good agreement with the available experimental observations. Furthermore, the influence of the speed-dependence and Dicke narrowing effects on the line contour was revealed by comparing the differences among the Hartmann-Tran, quadratic-speed-dependent Voigt, and Voigt profiles. The temperature dependence of each line-shape parameter was further parameterized using the triplet-power-law for three pure rotational 61, 6 ← 52, 3, 41, 4 ← 32, 1, and 31, 3 ← 22, 0 lines. These line-shape parameters will provide a comprehensive set of theoretical references for subsequent experimental measurements.

Evidence of a distinct collective mode in Kagome superconductors

The collective modes of the superconducting order parameter fluctuation can provide key insights into the nature of the superconductor. Recently, a family of superconductors has emerged in non-magnetic kagome materials AV3Sb5 (A = K, Rb, Cs), exhibiting fertile emergent phenomenology. However, the collective behaviors of Cooper pairs have not been studied. Here, we report a distinct collective mode in CsV3-xTaxSb5 using scanning tunneling microscope/spectroscopy. The spectral line-shape is well-described by one isotropic and one anisotropic superconducting gap, and a bosonic mode due to electron-mode coupling. With increasing x, the two gaps move closer in energy, merge into two isotropic gaps of equal amplitude, and then increase synchronously. The mode energy decreases monotonically to well below 2Δ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{2}}{{\\Delta }}$$\\end{document} and survives even after the charge density wave order is suppressed. We propose the interpretation of this collective mode as Leggett mode between different superconducting components or the Bardasis-Schrieffer mode due to a subleading superconducting component.

Clinical applicability of Linac-integrated CBCT based NIPAM 3D dosimetry: a dual-institutional investigation

Objective. To develop and benchmark a novel 3D dose verification technique consisting of polymer gel dosimetry (PGD) with cone-beam-CT (CBCT) readout through a two-institution study. The technique has potential for wide and robust applicability through reliance on CBCT readout. Approach. Three treatment plans (3-field, TG119-C-shape spine, 4-target SRS) were created by two independent institutions (Institutions A and B). A Varian Truebeam linear accelerator was used to deliver the plans to NIPAM polymer gel dosimeters produced at both institutions using an identical approach. For readout, a slow CBCT scan mode was used to acquire pre- and post-irradiation images of the gel (1 mm slice thickness). Independent gel analysis tools were used to process the PGD images (A: VistaAce software, B: in-house MATLAB code). Comparing planned and measured doses, the analysis involved a combination of 1D line profiles, 2D contour plots, and 3D global gamma maps (criteria ranging between 2%1 mm and 5%2 mm, with a 10% dose threshold). Main results. For all gamma criteria tested, the 3D gamma pass rates were all above 90% for 3-field and 88% for the SRS plan. For the C-shape spine plan, we benchmarked our 2% 2 mm result against previously published work using film analysis (93.4%). For 2%2 mm, 99.4% (Institution A data), and 89.7% (Institution B data) were obtained based on VistaAce software analysis, 83.7% (Institution A data), and 82.9% (Institution B data) based on MATLAB. Significance. The benchmark data demonstrate that when two institutions follow the same rigorous procedures gamma passing rates up to 99%, for 2%2 mm criteria can be achieved for substantively different treatment plans. The use of different software and calibration techniques may have contributed to the variation in the 3D gamma results. By sharing the data across institutions, we observe the gamma passing rate is more consistent within each pipeline, indicating the need for standardized analysis methods.

Inferring the iron K emissivity profiles of accretion discs irradiated by extended coronae

ABSTRACT One of the most promising methods to measure the spin of an accreting black hole is fitting the broad iron K$\alpha$ line in the X-ray spectrum. The line profile also depends on the geometry of the hard X-ray emitting corona. To put constraints on the black hole spin and corona geometry, it is essential to understand how do they affect the iron K$\alpha$ line emissivity profile. In this work, we present calculations of the illumination and the iron K$\alpha$ emissivity profiles performed with the Monte Carlo GR radiative transfer code monk. We focus on distinction between the illumination and emissivity profiles, which is in most previous studies neglected. We show that especially for the case of black hole X-ray binaries (BHXRBs), the difference is very large. For active galactic nuclei (AGNs), the emissivity profile has a more similar shape as the illumination profile, but it is notably steeper in the innermost region within a few gravitational radii. We find out that the different behaviour between AGN and BHXRB discs is due to the different energy spectra of the illuminating radiation. This suggests that the emissivity profile of the iron K$\alpha$ line cannot be determined by black hole spin and corona geometry alone and the energy spectrum of the illuminating radiation has to be taken into account. We also examined the effect of including the self-irradiation, and find it to be more important than the corona emission in BHXRBs.

Nanostructuring and Hardness Evolution in a Medium‐Mn Steel Processed by High‐Pressure Torsion Technique

Severe plastic deformation (SPD) is performed on a newly developed medium‐Mn steel with the composition of Fe–7.66Mn–2Ni–1Si–0.23C–0.05Nb (wt%) to achieve a nanocrystalline microstructure. The SPD process utilizes the high‐pressure torsion (HPT) technique, resulting in a nominal shear strain of approximately 36 000% after processing the disk for 10 turns. In X‐Ray diffraction line profile analysis, an increase in dislocation density to around 230 × 1014 m−2 is observed. In addition, under high strains, a face‐centered cubic (fcc) secondary phase emerges within the body‐centered cubic (bcc) matrix. In analytical transmission electron microscopy, using energy‐dispersive X‐Ray spectroscopy, it is indicated that the secondary‐phase particles are enriched in Al, Mn, and Si. As the strain imposed during HPT increases, the simultaneous rise in dislocation density and nanostructuring lead to material hardening. However, the partial phase transformation from bcc to fcc contributes to material softening. As a result of these two opposite effects, the hardness exhibits a non‐monotonic variation with the shear strain, displaying, for 10 turns of HPT, a lower hardness compared to fewer turns, despite the continuous increase in dislocation density and decrease in crystallite size.