Dispersion Measurements Research Articles

An Unusual Pulse Shape Change Event in PSR J1713+0747 Observed with the Green Bank Telescope and CHIME

The millisecond pulsar J1713+0747 underwent a sudden and significant pulse shape change between 2021 April 16 and 17 (MJDs 59320 and 59321). Subsequently, the pulse shape gradually recovered over the course of several months. We report the results of continued multifrequency radio observations of the pulsar made using the Canadian Hydrogen Intensity Mapping Experiment and the 100 m Green Bank Telescope in a 3 yr period encompassing the shape change event, between 2020 February and 2023 February. As of 2023 February, the pulse shape had returned to a state similar to that seen before the event, but with measurable changes remaining. The amplitude of the shape change and the accompanying time-of-arrival residuals display a strong nonmonotonic dependence on radio frequency, demonstrating that the event is neither a glitch (the effects of which should be independent of radio frequency, ν) nor a change in dispersion measure alone (which would produce a delay proportional to ν −2). However, it does bear some resemblance to the two previous “chromatic timing events” observed in J1713+0747, as well as to a similar event observed in PSR J1643−1224 in 2015.

Velocity Dispersions of Quiescent Galaxies in IllustrisTNG

We examine the central stellar velocity dispersion of subhalos based on IllustrisTNG cosmological hydrodynamic simulations. The central velocity dispersion is a fundamental observable that links galaxies with their dark matter subhalos. We carefully explore simulated stellar velocity dispersions derived with different definitions to assess possible systematics. We explore the impact of variation in the identification of member stellar particles, the viewing axes, the velocity dispersion computation technique, and simulation resolution. None of these issues impact the velocity dispersion significantly; any systematic uncertainties are smaller than the random error. We examine the stellar mass–velocity dispersion relation as an observational test of the simulations. At fixed stellar mass, the observed velocity dispersions significantly exceed the simulation results. This discrepancy is an interesting benchmark for the IllustrisTNG simulations because the simulations are not explicitly tuned to match this relation. We demonstrate that the stellar velocity dispersion provides measures of the dark matter velocity dispersion and the dark matter subhalo mass.

In-situ failure behavior and interfacial bonding of an interpenetrating metal matrix composite reinforced with lattice-like metallic glass (Ni60Nb20Ta20) preform

Metallic glasses (MG) have an amorphous atomic structure and exhibit several exceptional properties such as high strength, hardness associated with high elastic strain limit and elastic energy storage. But MGs are also prone to brittle fracture, making them difficult to use as monolithic structural components and might better be used as a reinforcement phase in hybrid composites such as metal matrix composites (MMC). The failure behavior of composites depends on the structure of the reinforcement phase. In this work, the failure behavior of an interpenetrating MMC reinforced with a MG (Ni60Nb20Ta20) lattice-like preform and AlSi12-matrix was investigated by in-situ compression tests under scanning electron microscopy to get a better understanding of the influence of the lattice-like preform and mechanical interference between both phases. Additionally, microstructure analysis by scanning transmission electron microscopy and energy dispersive X-ray measurements were carried out to gain insight into the chemical composition of the interfaces. The failure behavior in manufacturing direction of the MMC is dominated by shear stress whereas transversely to manufacturing direction by normal stress and exhibits therefore an anisotropic failure behavior. Investigations of the interfaces show more of a mechanical than chemical bonding but in general a good interfacial bonding was confirmed.

Effect of Hydrothermal Reaction Temperature on the Structural and Optical Properties of CuO Thin Films

Copper oxides are one of the first semiconductors studied for device applications. In the present work, CuO thin films were deposited on fluorine-doped tin oxide (FTO) substrates via hydrothermal method without using any surfactant and the effects of reaction temperature on the properties of the films were studied. CuO thin films deposited at different reaction temperatures were characterized for their structural and optical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results revealed that all the films consisted of polycrystalline CuO with a monoclinic crystal structure without any impurity phase. SEM images showed that chrysanthemum-like structures were formed, the number of which increased with increasing hydrothermal reaction temperature. EDAX measurements proved the existence of Cu and O elements and showed that all the films have Cu/O ratios close to unity. The Raman spectra confirmed the formation of crystalline CuO in all the films. From the optical absorption measurements, the direct forbidden energy gap values of the CuO thin films were found to be between 1.34 eV and 1.41 eV, depending on the hydrothermal reaction temperature.

The FAST Galactic Plane Pulsar Snapshot Survey – V. PSR J1901+0658 in a double neutron star system

ABSTRACT Double neutron star (DNS) systems offer excellent opportunities to test gravity theories. We report the timing results of PSR J1901+0658, the first pulsar discovered in the FAST Galactic Plane Pulsar Snapshot (GPPS) Survey. Based on timing observations by FAST over 5 yr, we obtain the phase-coherent timing solution and derive the precise measurements of its position, spin parameters, orbital parameters, and dispersion measure. It has a period of 75.7 ms, a period derivative of 2.169(6) × 10−19 s s−1, and a characteristic age of 5.5 Gyr. This pulsar is in an orbit with a period of 14.45 d and an eccentricity of 0.366. One post-Keplerian parameter, periastron advance, has been well-measured as being 0.00531(9) deg yr−1, from which the total mass of this system is derived to be 2.79(7) M⊙. The pulsar has the mass upper limit of 1.68 M⊙, so the lower limit for the companion mass is 1.11 M⊙. Because PSR J1901+0658 is a partially recycled pulsar in an eccentric binary orbit with such a large companion mass, it should be in a DNS system according to the evolution history of the binary system.

Conformation selection by ATP-competitive inhibitors and allosteric communication in ERK2.

Activation of the extracellular signal-regulated kinase-2 (ERK2) by phosphorylation has been shown to involve changes in protein dynamics, as determined by hydrogen-deuterium exchange mass spectrometry (HDX-MS) and NMR relaxation dispersion measurements. These can be described by a global exchange between two conformational states of the active kinase, named 'L' and 'R,' where R is associated with a catalytically productive ATP-binding mode. An ATP-competitive ERK1/2 inhibitor, Vertex-11e, has properties of conformation selection for the R-state, revealing movements of the activation loop that are allosterically coupled to the kinase active site. However, the features of inhibitors important for R-state selection are unknown. Here, we survey a panel of ATP-competitive ERK inhibitors using HDX-MS and NMR and identify 14 new molecules with properties of R-state selection. They reveal effects propagated to distal regions in the P+1 and helix αF segments surrounding the activation loop, as well as helix αL16. Crystal structures of inhibitor complexes with ERK2 reveal systematic shifts in the Gly loop and helix αC, mediated by a Tyr-Tyr ring stacking interaction and the conserved Lys-Glu salt bridge. The findings suggest a model for the R-state involving small movements in the N-lobe that promote compactness within the kinase active site and alter mobility surrounding the activation loop. Such properties of conformation selection might be exploited to modulate the protein docking interface used by ERK substrates and effectors.

Conformation selection by ATP-competitive inhibitors and allosteric communication in ERK2

Activation of the extracellular signal-regulated kinase-2 (ERK2) by phosphorylation has been shown to involve changes in protein dynamics, as determined by hydrogen-deuterium exchange mass spectrometry (HDX-MS) and NMR relaxation dispersion measurements. These can be described by a global exchange between two conformational states of the active kinase, named ‘L’ and ‘R,’ where R is associated with a catalytically productive ATP-binding mode. An ATP-competitive ERK1/2 inhibitor, Vertex-11e, has properties of conformation selection for the R-state, revealing movements of the activation loop that are allosterically coupled to the kinase active site. However, the features of inhibitors important for R-state selection are unknown. Here, we survey a panel of ATP-competitive ERK inhibitors using HDX-MS and NMR and identify 14 new molecules with properties of R-state selection. They reveal effects propagated to distal regions in the P+1 and helix αF segments surrounding the activation loop, as well as helix αL16. Crystal structures of inhibitor complexes with ERK2 reveal systematic shifts in the Gly loop and helix αC, mediated by a Tyr-Tyr ring stacking interaction and the conserved Lys-Glu salt bridge. The findings suggest a model for the R-state involving small movements in the N-lobe that promote compactness within the kinase active site and alter mobility surrounding the activation loop. Such properties of conformation selection might be exploited to modulate the protein docking interface used by ERK substrates and effectors.

Wave propagation in finite discrete chains unravelled by virtual measurement of dispersion properties

AbstractTravelling waves in circuit chains are studied to measure continuous dispersion. A lock‐in frequency meter (LIF) is suitable for precisely determining k for each set of waves in finite alternate LC chains, where LIF has been proven to be more accurate than the fast Fourier transform. In addition to the –k measurement, the wave impedance spectrum of the travelling wave can be measured simultaneously, for investigating the dispersion and splitting of pulse propagation. The measured dispersion is validated to be consistent with the derived theoretical equations. The result provides an independent way to precisely obtain dynamical system properties for chains composed of non‐ideal components, such as resistors for researching non‐Hermitian behaviour under dissipation. Systematical mapping of relative deviation dependence of wave dispersion measurement with LIF on different chain length and component variation is studied, indicating boundaries of 1%, 0.1%, and 0.01% precision for guidance of experiments.

(O-05) ESTRADIOL LEVELS IN MEXICAN MEN WITH ERECTILE DYSFUNCTION

Abstract Introduction and Objective Erectile dysfunction is associated with various psychological and physiological causes, including hormone levels such as testosterone. The role of estradiol in male sexual function is controversial, and studies reporting its impact on erectile function have been inconsistent. The aim of this study was to describe the levels of testosterone and estradiol in Mexican men with erectile dysfunction, based on the severity of dysfunction. Materials and Methods Hormonal levels of TSH, T3, T4, LH, FSH, total and free testosterone, and estradiol were measured in men over 18 years of age with erectile dysfunction, attending a clinic in Mexico. Clinical variables were analyzed, estimating measures of central tendency and dispersion for numerical variables, and absolute and relative frequencies for categorical variables. The proportion of men with abnormal levels of estradiol and testosterone was calculated based on the severity of erectile dysfunction. Results A total of 70 participants were included. The average age was 53.9 years old (+/- 11.8); 18.5% had severe dysfunction, 65.7% had moderate dysfunction, 14.2% had mild to moderate dysfunction, and 1.4% had mild dysfunction. 35.7% were diabetic, and 34.2% were hypertensive. 62.8% had abnormal levels in at least one of the evaluated hormones: 5.7% had low TSH levels; 2.8% had low T3 levels; 1.4% had low T4 levels; 5.7% had low and 7.1% had high total testosterone levels; 12.8% had low and 2.8% had high free testosterone levels; 17.1% had high prolactin levels; 1.4% had low and 10% had high LH levels; 5.7% had high FSH levels. Estradiol level was high in 6 men (8.5%), 1 had mild-moderate and 5 moderate dysfunction; 8 men had low estradiol levels (11.42%), 1 had mild-moderate, 4 moderate and 3 severe dysfunction. Conclusions Alteration on the levels of Estradiol was common in the analyzed group of patients with erectile dysfunction, especially in men with moderate dysfunction, observed in 12.8% of them. Financing Boston Medical Group.

Deciphering the immobilization of lipases on hydrophobic wrinkled silica nanoparticles

In this work, the adsorption of Candida antarctica B (CALB) and Rhizomucor miehei (RML) lipases into hydrophobic wrinkled silica nanoparticles (WSNs) is investigated. WSNs are hydrophobized by chemical vapor deposition. Both proteins are homogeneously distributed inside the pores of the nanoparticles, as confirmed by Transmission Electron Microscopy and Energy Dispersive X-ray measurements. The maximum enzyme load of CALB is twice that obtained for RML. Fourier Transform Infrared Spectroscopy confirms the preservation of the enzyme secondary structure after immobilization for both enzymes. Adsorption isotherms fit to a Langmuir model, resulting in a binding constant (KL) for RML 4.5-fold higher than that for CALB, indicating stronger binding for the former. Kinetic analysis reveals a positive correlation between enzyme load and RML activity unlike CALB where activity decreases along the enzyme load increases. Immobilization allows for enhancing the thermal stability of both lipases. Finally, CALB outperforms RML in the hydrolysis of ethyl-3-hydroxybutyrate. However, immobilized CALB yielded 20 % less 3-HBA than free lipase, while immobilized RML increases 3-fold the 3-HBA yield when compared with the free enzyme. The improved performance of immobilized RML can be explained due to the interfacial hyperactivation undergone by this lipase when immobilized on the superhydrophobic surface of WSNs.

Six-orders-of-magnitude-spanning dispersion measurement via Kalman filtering-aided white-light interferometry.

Dispersion plays a great role in ultrafast laser oscillators, ultrashort pulse amplifiers, and many other nonlinear optical dynamics. Therefore, dispersion measurement is crucial for device characterization, system design and nonlinear dynamics investigation therein. In this work, we demonstrate a versatile approach, i.e., Kalman filtering-aided white-light interferometry, for group delay dispersion (GDD) characterization. Extended Kalman filter is adopted to track the cosine-like interferogram, and to eliminate the unintended bias and the envelope, providing a nearly ideal phase retrieval and GDD estimation. The measurement range could span from tens of fs2 to tens of ps2, with an uncertainty of about 0.1%, enabling precise GDD measurement for diverse optical components, ranging from a millimeter-thick glass slide to highly dispersive chirped fiber Bragg gratings. Benefited by the simplicity, convenient setup, and easy operation as well as relatively low cost, this approach would help photonic device characterization, dispersion management and nonlinear dynamics investigation in the laboratory and work plant.

Magnetic Resonance Cholangiography Diagnosing Post-cholecystectomy Biliary Injuries.

This study aimed to determine the diagnostic performance of contrasted magnetic resonance cholangiography for detecting bile duct lesions following cholecystectomy. A retrospective case series study was conducted that included patients over 18 years of age with suspected bile duct injury after cholecystectomy, who underwent contrasted magnetic resonance cholangiography, and who also had endoscopic retrograde cholangiopancreatography, surgery, or subsequent clinical follow-up. The images were interpreted by two radiologists who assigned the type of lesion according to the Strasberg classification. Qualitative variables were represented by frequencies and proportions, while quantitative variables were described using measures of central tendency and dispersion. Sensitivity, specificity, and predictive values were assessed, along with interobserver variability, using the kappa index. We included 20 patients with a median age of 51.5 years (interquartile range: 35), and 14 (70%) were women. In all 20 patients, lesions were identified on magnetic resonance cholangiography, of which 19 were confirmed with the gold standard for a positive predictive value of 100% (hepatobiliary-specific contrast agents) and 92% (extracellular contrast). The most frequent lesions were Strasberg E2 and E4 in five patients each. The kappa index was 1 in determining the presence or absence of bile duct injury and 0.9 in the Strasberg classification. Contrasted magnetic resonance cholangiography is a method with high positive predictive value and almost perfect interobserver agreement for diagnosing bile duct lesions after cholecystectomy.

Measures of kurtosis: inadmissible for asymmetric distributions?

AbstractSkewness and kurtosis are natural characteristics of a distribution. While it has long been recognized that they are more intrinsically entangled than other characteristics like location and dispersion, this has recently been made more explicit by Eberl and Klar (Stat Papers 65:415–433, 2024) with regard to orders of kurtosis. In this paper, we analyze the implications of this entanglement on kurtosis measures in general and for several specific examples. As a key finding, we show that kurtosis measures that are defined in the classical order-based way, which is analogous to measures of location, dispersion and skewness, do not exist. This raises serious doubts about the frequent application of such measures to skewed data. We then consider old and new proposals for kurtosis measures and evaluate under which additional conditions they measure kurtosis in a meaningful way. Some measures also allow more specific representations of the influence of skewness on the measurement of kurtosis than are available in a general setting. This works particularly well for a family of newly introduced density-based kurtosis measures.

Does COVID-19 decrease price dispersion? Recent evidence from the airline industry

COVID-19 has caused substantial disruptions to the airline industry. This paper analyzes the impact of the pandemic on price dispersion in airfares. The sample includes ticket information from the DB1B database between 2018Q1 and 2021Q4. The fixed-effect panel instrument variable (IV) estimation finds evidence of decreased price dispersion during COVID-19. These results are robust to alternative measures of dispersion and subsamples. Furthermore, the subsample analyes reveal that, as the infection rate rises, the dispersion decreases more in markets where competition is more intense. Specifically, dispersion is lower on routes with the presence of low-cost carriers (LCCs) than those exclusively served by legacy carriers and on short-haul routes (≤500 miles) than long-haul routes (>500 miles). My analysis adds to the literature by exploiting the impact of changes in market conditions (i.e., demand shocks triggered by the COVID-19 recession) on price and price dispersion using the latest data.

The Effect of Salt Concentration on Dielectric Permittivity and Interfacial Polarization in Carbonate Rocks with Complex Pore Structure

Summary Broadband dielectric dispersion measurements are attractive options for the assessment of water-filled porosity. Dielectric permittivity is influenced by salinity as well as other rock/fluid properties. However, the effect of salinity on Maxwell-Wagner polarization (i.e., interfacial polarization) and dielectric permittivity in rock samples with complex pore structures requires further investigation. The objectives of this work are (a) to perform frequency-domain dielectric permittivity numerical simulations on 3D pore-scale rock samples at different salt concentration levels, (b) to quantify the effect of salinity on dielectric permittivity and interfacial polarization in the frequency range between 20 MHz and 5 GHz, and (c) to quantify the critical frequency (i.e., the frequency at which the relative permittivity becomes frequency-independent). We first perform pore-scale frequency domain dielectric permittivity simulations in fully water-saturated carbonate samples with complex pore structures to obtain the complex dielectric permittivity in the frequency range of 0.01–5 GHz and at different salinity levels. Next, we numerically create partially water/hydrocarbon-saturated water-wet samples and perform simulations at different salinity and water saturation levels to investigate the combined effect of salinity and water saturation on dielectric permittivity. Finally, we investigate how reliable conventional mixing models, such as the complex refractive index model (CRIM) and Hanai-Bruggeman (HB), are in the assessment of water saturation at different salinity levels. We used 3D pore-scale rock samples with complex pore structures from Austin Chalk, Estaillades Limestone, and Happy Spraberry formations. The increase in salinity from 2 to 50 parts per thousand (PPT) resulted in the relative permittivity to increase by 18% at 20 MHz. Similarly, an increase in salinity from 2 PPT to 50 PPT resulted in electrical conductivity to increase by 15 times at 20 MHz. However, at 5 GHz, the difference between the relative permittivity of the samples at different salinities was negligible. We demonstrated that the critical frequency was above 1 GHz. Thus, if complex dielectric permittivity at 1 GHz is being used, an accurate salinity assumption is required in the interpretation of conventional dielectric mixture models in carbonate formations. Finally, we observed 52% and 42% average relative errors in water saturation quantification when applying CRIM and HB models at all the frequencies of interest, respectively. The results also indicated that conventional models should not be used in the presence of uncertainty in salinity at lower frequencies. The results of this work quantified the frequency at which the water-filled pore volume rather than the Maxwell-Wagner polarization controls the relative permittivity of rock samples saturated with a wide range of brine salinity. Moreover, the results demonstrated that the relative permittivity of the rock samples with complex pore structures may still be significantly affected by the interfacial polarization even at 1 GHz. Moreover, the results suggested that the conventional mixture methods cannot reliably take into account the salt concentration of formation water, and this can lead to significant errors in reserves assessment.

Measurement of steep dispersion associated with magnetically assisted gain in Zeeman degenerate two-level system of cold atoms

We report on the measurements of magnetically assisted dispersion and gain in a Zeeman degenerate two-level system associated with the closed D 2 hyperfine transition Fg=3→Fe=2 cold cesium atoms. We use a Mach–Zehnder interferometer to measure the dispersive properties of this system in the presence of a magnetic field, transversal to the quantization direction, when the atomic system is excited by a coupling and probe beams with orthogonal polarizations. We have measured the spectrum of the refraction index for different magnitudes of the external magnetic field and different coupling beam intensities. A previously published theoretical model, using a simpler atomic transition Fg=1→Fe=0 , accounts reasonably for the experimentally observed gain and dispersive lineshapes.

Novel bulk triaxial residual stress mapping in an additive manufactured bridge sample by coupling energy dispersive X-ray diffraction and contour method measurements

A novel approach for determining triaxial residual stress states by coupling energy dispersive X-ray diffraction and contour method measurements is provided and validated in a Ti‐5Al‐5V‐5Mo‐3Cr additive manufactured (AM) bridge sample. Synchrotron X-ray diffraction (SXRD) can provide relatively fine spatial resolution (on the order of 10–100 µm) for mapping 3D elastic strain fields within a sample. However, for samples with dimensions larger than one or two centimeters the path length can get prohibitive as both constant wavelength and energy dispersive SXRD are based upon transmission measurements. As an example, for a plate-like sample geometry where the thickness is limited (less than a centimeter) it is trivial to measure the longitudinal and height direction elastic strain components with excellent in-plane spatial resolution (∼100 µm) and a somewhat lower through-thickness resolution (10–15 times larger) but obtaining the through thickness component is often not possible as the beam path must be parallel to one of the large dimensions of the plate. While small samples of low Z-number alloys (e.g., Ti or Al) allow determination of the three elastic strain components, this is often not the case for higher Z alloys (e.g., Fe or Ni) or large samples where some strain components can be indeterminable. To overcome these limitations, this work applies a combination of synchrotron X-ray diffraction and the contour method (a mechanical relaxation technique), to determine the triaxial stress state. This novel combination is demonstrated and validated in a relatively small additive manufactured sample where all three orthogonal strain components are accessible via X-ray diffraction for stress determination. The paper also explores methods for determining the strain-free lattice parameter, typically obtained from a small stress-free reference sample. This work shows that a small size AM sample is not stress free, producing unreliable magnitudes of strain and stress. Instead, a strain-free lattice parameter is determined using residual stress equilibrium conditions, which gives consistent strain and stress trends for both X-ray diffraction (alone) and the new diffraction-contour coupling technique. This demonstrates that the coupling technique can be confidently applied to samples to determine stress when path length (size or Z-number) prohibit determination of three orthogonal strain components via diffraction.

TransientX: A high-performance single-pulse search package

Context. Radio interferometers composed of a large array of small antennas possess large fields of view, coupled with high sensitivities. For example, the Karoo Array Telescope (MeerKAT) achieves a gain of up to 2.8 KJy−1 across its >1 deg2 field of view. This capability significantly enhances the survey speed for pulsars and fast transients. It also introduces challenges related to the high data rate, which reaches a few Tb s−1 for MeerKAT, and it requires substantial computing power. Aims. To handle the high data rate of surveys, we have developed a high-performance single-pulse search software called “TransientX”. This software integrates multiple processes into one pipeline, which includes radio-frequency interference mitigation, dedispersion, matched filtering, clustering, and candidate plotting. Methods. In TRANSIENTX, we developed an efficient CPU-based dedispersion implementation using the sub-band dedispersion algorithm. Additionally, TRANSIENTX employs the density-based spatial clustering of applications with noise (DBSCAN) algorithm to eliminate duplicate candidates, using an efficient implementation based on the kd-tree data structure. We also calculate the decrease of signal-to-noise ratio (s/N) resulting from dispersion measure, boxcar width, spectral index, and pulse-shape mismatches. Remarkably, we find that the decrease of S/N resulting from the mismatch between a boxcar-shaped template and a Gaussian-shaped pulse with scattering remains relatively small, at approximately 9%, even when the scattering timescale is ten times that of the pulse width. Additionally, the decrease in the S/N resulting from the spectral index mismatch becomes significant with multi-octave receivers. Results. We have benchmarked the individual processes, including dedispersion, matched filtering, and clustering. Our dedispersion implementation can be executed in real time using a single CPU core on data with 4096 dispersion measure trials, which consist of 4096 channels and have a time resolution of 153 µs. Overall, TRANSIENTX offers the capability for efficient CPU-only real-time single-pulse searching.

Comparison of Fibroscan, Shear Wave Elastography, and Shear Wave Dispersion Measurements in Evaluating Fibrosis and Necroinflammation in Patients Who Underwent Liver Biopsy.

Our aim was to predict these stages of hepatic fibrosis and necroinflammation using measurements from two-dimensional shear wave elastography (2D-SWE), transient elastography (Fibroscan, TE), and shear wave dispersion (SWD). In this prospectively designed study, chronic liver patients with nonspecific etiology whose biopsy was performed for up to 1 week were included. Two-dimensional SWE, SWD, and TE measurements were performed. The METAVIR and F-ISHAK classification was used for histopathological evaluation. Two-dimensional SWE and TE were considered significant for detecting hepatic fibrosis. In distinguishing ≥F2, for 2D-SWE, area under the receiver operating characteristics (AUROC) was 0.86 (confidence interval [CI], 0.75-0.96) for the cutoff value of 8.05 kPa ( P = 0.003); for TE, AUROC was 0.79 (CI, 0.65-0.94) for the cutoff value of 10.4 kPa ( P < 0.001). No significance was found for TE in distinguishing ≥F3 ( P = 0.132). However, for 2D-SWE, a cutoff value of 10.45 kPa ( P < 0.001), with AUROC = 0.87 (CI, 0.78-0.97) was determined for ≥F3. Shear wave dispersion was able to determine the presence of necroinflammation ( P = 0.016) and a cutoff value of 15.25 (meter/second)/kiloHertz ([m/s]/kHz) ( P = 0.006) and AUROC of 0.71 (CI, 0.57-0.85) were calculated for distinguishing ≥A2. In addition, a cutoff value of 17.25 (m/s)/kHz ( P = 0.023) and AUROC = 0.72 (CI, 0.51-0.93) were found to detect severe necroinflammation. The cutoff value for SWD was 15.25 (m/s)/kHz ( P = 0.013) for detecting ≥A2 in the reversible stage of fibrosis (F0, F1, and F2), and AUROC = 0.72 (CI, 0.56-0.88). Two-dimensional SWE and TE measurements were significant in detecting the irreversible stage and the stage that should be treated in hepatic fibrosis noninvasively. Shear wave dispersion measurements were significant in detecting necroinflammation noninvasively.

Modeling the Radial Distribution of Pulsars in the Galaxy

The Parkes 20 cm multibeam pulsar surveys have discovered nearly half of the known pulsars and revealed many distant pulsars with high dispersion measures. Using a sample of 1301 pulsars from these surveys, we have explored the spatial distribution and birth rate of normal pulsars. The pulsar distances used to calculate the pulsar surface density are estimated from the YMW16 electron-density model. When estimating the impact of the Galactic background radiation on our survey, we projected pulsars in the galaxy onto the Galactic plane, assuming that the flux density distribution of pulsars is uniform in all directions, and utilized the most up-to-date background temperature map. We also used an up-to-date version of the ATNF Pulsar Catalogue to model the distribution of pulsar flux densities at 1400 MHz. We derive an improved radial distribution for the pulsar surface density projected onto the Galactic plane, which has a maximum value at ∼4 kpc from the Galactic center. We also derive the local surface density and birth rate of pulsars, obtaining 47 ± 5 kpc−2 and ∼4.7 ± 0.5 kpc−2 Myr−1, respectively. For the total number of potentially detectable pulsars in the galaxy, we obtain (1.1 ± 0.2) × 104 and (1.1 ± 0.2)×105 before and after applying the Tauris & Manchester beaming correction model. The radial distribution function is used to estimate the proportion of pulsars in each spiral arm and the Galactic center.