Average Distance Research Articles

Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud

Significant mass loss in the red supergiant (RSG) phase has great influence on the evolution of massive stars and their final fate as supernovae. We present near-infrared interferometric imaging of the circumstellar environment of the dust-enshrouded RSG WOH G64 in the Large Magellanic Cloud. WOH G64 was observed with the GRAVITY instrument at ESO's Very Large Telescope Interferometer (VLTI) at 2.0--2.45 mu m . We succeeded in imaging the innermost circumstellar environment of WOH G64 -- the first interferometric imaging of an RSG outside the Milky Way. The reconstructed image reveals elongated compact emission with a semimajor and semiminor axis of sim 2 and sim 1.5 mas (sim 13 and 9 $R_ star ), respectively. The GRAVITY data show that the stellar flux contribution at 2.2 mu m \ at the time of our observations in 2020 is much lower than predicted by the optically and geometrically thick dust torus model based on the VLTI/MIDI data taken in 2005 and 2007. We found a significant change in the near-infrared spectrum of WOH G64: while the (spectro)photometric data taken at 1--2.5 mu m \ before 2003 show the spectrum of the central RSG with H$_2$O absorption, the spectra and prime photometric data taken after 2016 are characterized by a monotonically rising continuum with very weak signatures of H$_2$O . This spectral change likely took place between December 2009 and 2016. On the other hand, the mid-infrared spectrum obtained in 2022 with VLT/VISIR agrees well with the spectra obtained before 2007. The compact emission imaged with GRAVITY and the near-infrared spectral change suggest the formation of hot new dust close to the star, which gives rise to the monotonically rising near-infrared continuum and the high obscuration of the central star. The elongation of the emission may be due to the presence of a bipolar outflow or effects of an unseen companion.

The cool brown dwarf Gliese 229 B is a close binary.

Owing to their similarities with giant exoplanets, brown dwarf companions of stars provide insights into the fundamental processes of planet formation and evolution. From their orbits, several brown dwarf companions are found to be more massive than theoretical predictions given their luminosities and the ages of their host stars1-3. Either the theory is incomplete or these objects are not single entities. For example, they could be two brown dwarfs each with a lower mass and intrinsic luminosity1,4. The most problematic example is Gliese 229 B (refs. 5,6), which is at least 2-6 times less luminous than model predictions given its dynamical mass of 71.4 ± 0.6 Jupiter masses (MJup) (ref. 1). We observed Gliese 229 B with the GRAVITY interferometer and, separately, the CRIRES+ spectrograph at the Very Large Telescope. Both sets of observations independently resolve Gliese 229 B into two components, Gliese 229 Ba and Bb, settling the conflict between theory and observations. The two objects have a flux ratio of 0.47 ± 0.03 at a wavelength of 2 μm and masses of 38.1 ± 1.0 and 34.4 ± 1.5 MJup, respectively. They orbit each other every 12.1 days with a semimajor axis of 0.042 astronomical units (AU). The discovery of Gliese 229 BaBb, each only a few times more massive than the most massive planets, and separated by 16 times the Earth-moon distance, raises new questions about the formation and prevalence of tight binary brown dwarfs around stars.

Exploring the density and morphology of coconut structures at two locations: a time-based analysis using computer tomography.

The study aimed to observe the internal structure of coconuts from two locations (coastal and non-coastal) using computed tomography (CT). Seventy-six mature coconuts were collected from Wenchang and Ding'an cities in Hainan Province. These coconuts were scanned four times using CT, with a two-week interval between each scan. CT data were post-processed to reconstruct two-dimensional slices and three-dimensional models. The density and morphological parameters of coconut structures were measured, and the differences in these characteristics between the two groups and the changes over time were analyzed. Time and location had interactive effects on CT values of embryos, solid endosperms and mesocarps, morphological information such as major axis of coconut, thickness of mesocarp, volume of coconut water and height of bud (p<0.05). Planting location and observation time can affect the density and morphology of some coconut structures.

Bending response of cover-plated CFS built-up sections: Testing, numerical parametric analysis and design

This study investigates the bending response of cover-plated cold-formed steel (CPCFS) built-up sections comprising of plain channel members under pure bending achieved through four-point loading, both experimentally and numerically. Channels were appropriately spaced back-to-back and screw-fastened at the flanges using cover-plates on the tension and compression sides. This novel design for the CPCFS built-up section combines the benefits of box-profile (closed sections) and I-profile (open sections), including high strength-to-weight ratio, simplified fabrication, and enhanced torsional rigidity. Eight CPCFS built-up sections with different cross-sectional aspect ratios were tested for bending about the major axis under simply supported end conditions. Flexural strengths, failure modes, and moment-curvature plots were discussed. Subsequently, a finite element model was developed in ABAQUS and validated against the test response obtained. Afterwards, an extensive parametric analysis was conducted to assess the variational effect of aspect ratios, cross-sectional slenderness, and plate slenderness on the ultimate moment capacity of the CPCFS built-up beams. Finally, the adequacy of the codified Continuous Strength Method (CSM) and Direct Strength Method (DSM) for CPCFS built-up beams was evaluated. Generally, it was observed that the flexural strengths predicted by the codified CSM and DSM for CPCFS built-up beams were unconservative and conservative, respectively. Suitable modifications were proposed to both DSM and CSM to accurately predict the flexural strength of CPCFS built-up beams, which were eventually verified through a reliability analysis.

Stark seasonal contrast of fine aerosol levels, composition, formation mechanism, and characteristics in a polluted megacity.

In this study, we investigated the temporal variation of organic and inorganic aerosol with its optical properties in Mumbai (India), an urban coastal region. Mean PM2.5concentrations during the sampling period were 175μg/m3 (winter) and 90μg/m3 (summer). During winter, the average concentrations of organic (OC), elemental (EC), and water-soluble organic carbon (WSOC) were three times higher than in summer. Secondary organic carbon (SOC) contribution in OC was higher in summer (78%) than in winter (53%), and strong solar radiation in summer likely caused this outcome. Aerosols were slightly acidic in both seasons, with an average pH of 5.7 (winter) and 6.0 (summer). A correlation was observed between SOC and the acidity of particles in summer (R2 = 0.6), indicating some amount of acid-catalysed SOC formation. In both seasons, the sulphate oxidation ratio (SOR) was higher than the nitrate oxidation ratio (NOR), which may reflect a preference for SO2 oxidation over NO2 or the difference in partitioning ammonium nitrate into ammonium sulphate under high RH. The dominant mechanism of SOC formation (gas vs aqueous phase oxidation) also showed seasonal variation. In winter, a relatively steep reduced major axis (RMA) slope of O3/CO suggests gas phase oxidation was the dominant mechanism of SOC production. Winter has more BrC fraction than summer, indicating higher absorbing aerosols, though the efficiency of absorbing the light was higher in summer. To assess the radiative forcing of PM2.5 on a local scale, an effective carbon ratio (ECR) was computed. The findings pointed to a local radiative heating impact caused by PM2.5. The spectral slope ratio and MAE at 250 to 300nm ratio (E2/E3) revealed a higher abundance of high molecular weight species in WSOC during summer than in winter.

Distribution of microplastics on sandy beaches in western and southern Japan and their fate in the oceans

The Japanese archipelago is surrounded by the Sea of Japan, the Sea of Okhotsk, the Pacific Ocean, and the East China Sea. The oceans are known to be contaminated by waste artifacts (marine litter). To investigate how these artifacts contaminate sandy beaches in Japan and their fate in the oceans, we sampled sand from 19 sandy beaches ranging from the western area of the main island of Japan (Honshu), which faces the Sea of Japan, to the westernmost island in the Japanese archipelago (Yonaguni Island), which faces the East China Sea. Almost all beaches were contaminated by marine litter. The maximum density by number of pieces was 604,600 per m3 in a 2-cm depth of sand on Yonaguni Island. Polystyrene foam was the most common artifact, and plastic fragments were second. The densities of artifacts by number and weight, and the type of artifacts, varied by location. A statistically significant positive relationship between the weights of artifacts and natural objects was observed, suggesting that they experience similar fates in the oceans. The major axis of the polystyrene foam in the Yonaguni area differed significantly from those in the Shimane, Tsushima, and Okinawa areas. The major axis in the Tsushima area significantly differed from those in all other studied areas. This study found the geological difference in the distribution and the major axis of polystyrene foams. These differences may be relevant to environmental physical factors (wind, rain, and waves), chemical alterations by ultraviolet rays, exposed time, the gyre, and local currents.

HD 28185 revisited: an outer planet, instead of a brown dwarf, on a Saturn-like orbit

ABSTRACT As exoplanet surveys reach ever-higher sensitivities and durations, planets analogous to the Solar system giant planets are increasingly within reach. HD 28185 is a Sun-like star known to host a $m\sin i=6~M_\mathrm{ J}$ planet on an Earth-like orbit; more recently, a brown dwarf with a more distant orbit has been claimed. In this work, we present a comprehensive re-analysis of the HD 28185 system, based on 22 yr of radial velocity (RV) observations and precision Hipparcos–Gaia astrometry. We confirm the previous characterization of HD 28185 b as a temperate giant planet, with its $385.92^{+0.06}_{-0.07}$ d orbital period giving it an Earth-like incident flux. In contrast, we substantially revise the parameters of HD 28185 c; with a new mass of $m=6.0\pm 0.6~M_\mathrm{ J}$, we reclassify this companion as a super-Jovian planet. HD 28185 c has an orbital period of $24.9^{+1.3}_{-1.1}$ yr, a semimajor axis of $8.50^{+0.29}_{-0.26}$ au, and a modest eccentricity of $0.15\pm 0.04$, resulting in one of the most Saturn-like orbits of any known exoplanet. HD 28185 c lies at the current intersection of detection limits for RVs and direct imaging, and highlights how the discovery of giant planets at $\approx$10 au separations is becoming increasingly routine.

Review on Intrinsic Shape of Elliptical Galaxies

: Elliptical galaxies, as one of the fundamental types of galaxies, have attracted astronomers due to their intriguing properties. In this review, we explore the intrinsic shape of elliptical galaxies, a field that plays a pivotal role in understanding their formation, evolution, and interactions within the cosmos. Methods for intrinsic shape determination using photometric and kinematic methods are extensively discussed. The use of photometric data and surface brightness profiles to derive the intrinsic shapes of elliptical galaxies is examined and triaxial models are reviewed. Constraining the intrinsic shapes of elliptical galaxies is crucial to understanding their formation histories. Elliptical galaxies are characterized by their ellipsoidal, rather than disk-like, shapes, and understanding the underlying factors and their intrinsic shapes of elliptical galaxies determination provides valuable insights into their formation, evolution, and the broader context of galaxy morphology. One key aspect of studying the intrinsic shape of elliptical galaxies involves the analysis of their axial ratios, which describe the flattening of the galaxy along different axes. The axial ratio is defined as the ratio of the semi-minor axis to the semi-major axis of the ellipse representing the galaxy's cross-section. The intrinsic shape can vary from nearly spherical (axial ratio close to 1) to highly elongated (axial ratio significantly different from 1).

Intra-Aneurysmal High-Resolution 4D MR Flow Imaging for Hemodynamic Imaging Markers in Intracranial Aneurysm Instability.

Prediction of aneurysm instability is crucial to guide treatment decisions and to select appropriate patients with unruptured intracranial aneurysms (IAs) for preventive treatment. High-resolution 4D MR flow imaging and 3D quantification of aneurysm morphology could offer insights and new imaging markers for aneurysm instability. In this cross-sectional study, we aim to identify 4D MR flow imaging markers for aneurysm instability by relating hemodynamics in the aneurysm sac to 3D morphologic proxy parameters for aneurysm instability. In 35 patients with 37 unruptured IAs, a 3T MRA and a 7T 4D MRI flow scan were performed. Five hemodynamic parameters-peak-systolic wall shear stress (WSSMAX) and time-averaged wall shear stress (WSSMEAN), oscillatory shear index (OSI), mean velocity, and velocity pulsatility index-were correlated to 6 3D morphology proxy parameters of aneurysm instability-major axis length, volume, surface area (all 3 size parameters), flatness, shape index, and curvedness-by Pearson correlation with 95% CI. Scatterplots of hemodynamic parameters that correlated with IA size (major axis length) were created. WSSMAX and WSSMEAN correlated negatively with all 3 size parameters (strongest for WSSMEAN with volume (r = -0.70, 95% CI -0.83 to -0.49) and OSI positively (strongest with major axis length [r = 0.87, 95% CI 0.76-0.93]). WSSMAX and WSSMEAN correlated positively with shape index (r = 0.61, 95% CI 0.36-0.78 and r = 0.49, 95% CI 0.20-0.70, respectively) and OSI negatively (r = -0.82, 95% CI -0.9 to -0.68). WSSMEAN and mean velocity correlated negatively with flatness (r = -0.35, 95% CI -0.61 to -0.029 and r = -0.33, 95% CI -0.59 to 0.007, respectively) and OSI positively (r = 0.54, 95% CI 0.26-0.74). Velocity pulsatility index did not show any statistically relevant correlation. Out of the 5 included hemodynamic parameters, WSSMAX, WSSMEAN, and OSI showed the strongest correlation with morphologic 3D proxy parameters of aneurysm instability. Future studies should assess these promising new imaging marker parameters for predicting aneurysm instability in longitudinal cohorts of patients with IA.

Automatic Detection and Identification of Calcareous Nannofossils in Chalk Using Deep Learning: A Proof-of-Concept Study for Biostratigraphy and Climate Research

Calcareous nannofossils serve as crucial indicators for establishing the biostratigraphic age of chalk macrofossil specimens in natural science collections. Better age control of specimens collected several hundred years ago enables us to uncover the dark data hidden within these collections and incorporate these data into current research projects, examining ecosystem response to past climate change. However, the manual identification of these microscopic organisms is laborious and subjective, and so we are harnessing deep learning techniques for automatic nannofossil detection and identification. This approach required the construction of a robust dataset, currently comprising over 100,000 labelled images, complemented by the development of multiple specialised deep learning models. While some models focus on detecting target species, others are dedicated to species classification. Evaluation on an independent test set showcases the efficacy of our methodology, with the current detection model achieving a balanced accuracy of 93%. Similarly, the classification model demonstrates robust performance, attaining an average balanced accuracy of 96%. Furthermore, as well as assisting with our biostratigraphic studies, the dataset of accurately labelled images has enabled us to test other aspects of ecosystem response. For example, examining morphometric changes in nannofossils over geological time can provide valuable insights into the potential impact of current global warming on modern phytoplankton assemblages (Mancini et al. 2021). This is particularly important for coccolithophores (Young et al. 2005), which play a critical role as primary producers in the global carbon cycle. A decrease in their size could lead to bottom-up ecosystem impacts and reduced carbon sequestration (Poulton et al. 2007, Krumhardt et al. 2017). Using our dataset, we conducted a deep-learning-enhanced automatic morphometric analysis focusing on the nannofossil species, Tranolithus orionatus. Our analysis revealed that two key morphometric parameters, minor axis and area size, showed statistically significant differences between the Cenomanian stage (approximately 100.5 to 93.9 million years ago) and the post-Cenomanian stages of the Late Cretaceous (approximately 93.9 to 66.0 million years ago). Kolmogorov-Smirnov tests (Massey 1951) between the two samples yielded p-values of 0.039 for the minor axis and 0.031 for the area size. Understanding these morphometric changes is crucial due to the close parallels between current climate projections and the warming and greenhouse climate of the Late Cretaceous, particularly the Cenomanian-Turonian boundary event (Arthur et al. 1990). Insights into how organisms changed morphologically during past periods of environmental stress can help us more effectively predict future responses of organisms under similar conditions (Razmjooei et al. 2020). These findings underscore the effectiveness of our approach in automating the identification and recognition of chalk nannofossils, helping to unlock natural science collections and to address key questions related to marine response to past climate change.

Automatic Image Analysis Method as a Tool to Evaluate the Anisotropy of Autoclaved Aerated Concrete for Moisture and Heat Transport

In this article, the results of studies testing the anisotropy of autoclaved aerated concrete in terms of water and heat transport are presented. Using image analysis techniques, a study was conducted on four different samples of concrete produced in the same process. To ensure the comparability of results, the pictures were taken from a fixed distance with the same lens settings trimmed to a set size. Cross-sectional profiles of the material were examined and were arranged in two directions: perpendicular and parallel to the growth direction occurring in the autoclave. For each block, approximately 4750 objects were obtained, with an average of 2700 objects along the wall and 2050 across it. As a result of the comparative analysis, metrics concerning pores, significantly distinguishing the profile direction, were identified. These included the pore area (area), the maximum and minimum distance between points on the perimeter (Feret, MinFeret), lengths of the major and minor axes of the fitted ellipse (major, minor), and the ratio of the area of selection to its convex hull (solidity). As a reference, standard investigations were conducted for moisture transport using the time domain reflectometry setup and for thermal conductivity values using the steady-state heat flow plate apparatus.

8229 Prevalence of Thyroid Cancer in Patients with Hashimotos Thyroiditis Presenting Concomitant Thyroid Nodular Disease

Abstract Disclosure: M.A. Alvarez Castillo: None. L. Sanchez Arriaga: None. A. Segovia Palomo: None. Introduction: Hashimoto's thyroiditis (HT) is the most frequent autoimmune thyroid disease and the main cause of goiter and hypothyroidism; it induces a process of aseptic autoimmune inflammation. Fibroinflammatory changes lead to the development of thyroid nodules (TN), additionally chronic inflammation is an important player in the development of cancer, although this association is controversial. The prevalence of thyroid cancer (TC) in patients with HT ranges from 0.61-58.4% (25.01%), being higher than in patients with TN without concomitant HT. Objective: To know the prevalence of malignancy in patients with HT who present thyroid nodular disease. Methodology: An observational, descriptive, retrospective, and longitudinal study was carried out. Patients with HT diagnosis were selected by measuring Ab TPO and/or Ab TG who presented an ultrasound diagnosis of TN and FNAB of the thyroid lesion had been performed. Descriptive statistics and linear regression were used. Results: 87 patients: 6 (6.9%) men and 81 (93.1%) women aged 47.9 (12.7) years. 4 (4.5%) required FNAB in 2 TN, for a total of 91 TN studied. 64% had a diagnosis of hypothyroidism and were taking LT4, TSH 4.40 (4.44) mUI/mL, FT4 1.00 (0.27) ng/dL. Mean Ab TPO was 794.7 ± 1354.6. Diagnosis time 19.5 (29.1) months. 39.6% the detection was made by the patient and 35.2% by the doctor. Major axis was 18.8 (12.1) mm. Ultrasound pattern of single TN 58.2% and multinodular 41.8%. Median TIRADS was 4, with a mode of 5. 81.3% reported Bethesda II and 18.7% malignant or suspected, were sent for surgery, malignancy was confirmed in 16/ 17 lesions. 14 (15.3%) were TPC and 2 lymphomas, the main subtypes were classic papillary and NHL, respectively. Mode of ATA risk was intermediate. Multivariate analysis only TIRADS represented risk factor (OR 2.08) Conclusions: The frequency of TC in our population was 15.3%, which reflects a higher prevalence of malignancy in thyroid nodules in patients with chronic thyroiditis, in accordance with what has been reported in other series. Presentation: 6/3/2024

Enhanced Extreme Mass Ratio Inspiral Rates and Intermediate Mass Black Holes.

Extreme mass ratio inspirals (EMRIs) occur when stellar-mass compact objects begin a gravitational wave (GW) driven inspiral into massive black holes. EMRI waveforms can precisely map the surrounding spacetime, making them a key target for future space-based GW interferometers such as LISA, but their event rates and parameters are massively uncertain. One of the largest uncertainties is the ratio of true EMRIs (which spend at least thousands of orbits in the LISA band) and direct plunges, which are in-band for at most a handful of orbits and are not detectable in practice. In this Letter, we show that the traditional dichotomy between EMRIs and plunges-EMRIs originate from small semimajor axes, plunges from large-does not hold for intermediate-mass black holes with masses M_{•}≲10^{5}M_{⊙}. In this low-mass regime, a plunge always has an O(1) probability of failing and transitioning into a novel "cliffhanger" EMRI. Cliffhanger EMRIs are more easily produced for larger stellar-mass compact objects, and are less likely for smaller ones. This new EMRI production channel can dominate volumetric EMRI rates n[over ˙]_{EMRI} if intermediate-mass black holes are common in dwarf galactic nuclei, potentially increasing n[over ˙]_{EMRI} by an order of magnitude.

Subhalos in Galaxy Clusters: Coherent Accretion and Internal Orbits

Subhalo dynamics in galaxy cluster host halos govern the observed distribution and properties of cluster member galaxies. We use the IllustrisTNG simulation to investigate the accretion and orbits of subhalos found in cluster-size halos. We find that the median change in the major axis direction of cluster-size host halos is approximately 80° between a ∼ 0.1 and the present day. We identify coherent regions in the angular distribution of subhalo accretion, and ∼68% of accreted subhalos enter their host halo through ∼38% of the surface area at the virial radius. The majority of galaxy clusters in the sample have ∼2 such coherent regions. We further measure angular orbits of subhalos with respect to the host major axis and use a clustering algorithm to identify distinct orbit modes with varying oscillation timescales. The orbit modes correlate with subhalo accretion conditions. Subhalos in orbit modes with shorter oscillations tend to have lower peak masses and accretion directions somewhat more aligned with the major axis. One orbit mode, exhibiting the least oscillatory behavior, largely consists of subhalos that accrete near the plane perpendicular to the host halo major axis. Our findings are consistent with expectations from inflow from major filament structures and internal dynamical friction: most subhalos accrete through coherent regions, and more massive subhalos experience fewer orbits after accretion. Our work offers a unique quantification of subhalo dynamics that can be connected to how the intracluster medium strips and quenches cluster galaxies.

Gaseous Dynamical Friction on Elliptical Keplerian Orbits

We compute the gaseous dynamical friction force experienced by massive perturbers on elliptical Keplerian orbits. Using linear perturbation theory, we investigate the density wake morphology, dynamical friction force, and secular orbital evolution for massive single perturbers as well as equal-mass binaries embedded in a homogeneous, static medium. In all cases, the rate of change in the semimajor axis is found to be negative (as expected), whereas the rate of change in eccentricity is negative for strictly subsonic trajectories and positive for strictly supersonic trajectories. Transonic orbits can experience both positive and negative torques during the course of an orbit, with some growing in eccentricity and others circularizing. We observe all initial orbits becoming highly supersonic and eccentric (over sufficiently long timescales) due to a relentless semimajor axis decay increasing the Mach number and subsequent eccentricity driving. We compare our findings to previous studies for rectilinear and circular motion while also making our data for the evolution of Keplerian orbits available.

Porous dielectric design for high-performance flexible shear sensors

Abstract Flexible sensors, renowned for their exceptional adaptability, are widely utilized in areas such as robotics and healthcare monitoring. Currently, understanding the relationship between the structure and performance of flexible shear sensors has become increasingly important. In this study, the structural characteristics of porous flexible shear sensors and their impact on performance were analyzed using Finite Element Method (FEM). The investigation focused on three factors: porosity, pore size, and the shape of elliptical pores. The findings suggest that augmenting the porosity substantially boosts the shear sensitivity of the sensor, whereas the pore size exerts a relatively minor influence on sensitivity. Furthermore, compared to circular ones, elliptical pores can further increase the shear sensitivity of the sensor, particularly when the ellipse’s major axis is oriented horizontally. These findings are of significant reference value for designing and optimizing high-performance flexible shear sensors.

Evaluation of radiotherapy planning approaches for head and neck patients with tumors close to the skin surface.

In radiotherapy of the head and neck (H&N) it is common for the clinical target volume (CTV) to extend to the patient's skin. Adding a margin for set-up uncertainty and delivery creates a planning target volume (PTV) that extends beyond the patient surface. This can result in excessive fluence being delivered to the build-up region and therefore the skin. This study evaluates four different planning methods used when inverse-planning H&N radiotherapy treatments with CTV extending to the skin. The aim of the study was to determine which planning method gives superior plan quality. Ten H&N cancer patients with a CTV contoured to the skin were inverse-planned using four planning methods. The planning methods compared were: cropping the optimization PTV back from the skin surface by 5.0, 3.0, and 0.0mm and a virtual bolus method. For each planning method, the increased fluence at the skin surface was analyzed. The CTV coverage and skin doses were compared. Plan robustness was evaluated by applying an isocenter shift of ±3.0mm in the major axes. The planning method cropping the PTV 0.0mm from the skin surface results in an increased fluence in the build-up region. The average volume of CTV receiving 98% of the prescription dose was 89.6%±3.4%, 91.6%±2.4%, and 93.5%±1.7% when cropped 5.0, 3.0, and 0.0mm, respectively, and 93.4%±2.1% for the virtual bolus method. Introducing plan uncertainty affects CTV coverage the most when cropping 5.0mm. When plan uncertainties are considered the methods of cropping 5.0, 3.0mm, and the virtual bolus method have the same average skin dose within ±0.3%. This study shows that a virtual bolus planning method results in no increased fluence at the patient's surface, improves CTV coverage, and is the most robust to changes in setup and patient anatomy.

G321.3–3.9: A new supernova remnant observed with multi-band radio data and in the SRG/eROSITA All-Sky Surveys

Aims. G321.3–3.9 was first identified as a partial shell at radio frequencies a few decades ago. Although it continued to be observed, no additional studies were undertaken until recently. Methods. In this paper, we present results from a large selection of radio and X-ray data that cover the position of G321.3–3.9. We confirmed G321.3–3.9 as a new supernova remnant (SNR) using data collected by several radio surveys, spanning a frequency range from 200 to 2300 MHz. Stacked eROSITA data from four consecutive all-sky surveys (eRASS:4) provide spectro-imaging information in the energy band 0.2–8.0 keV. Results. G321.3–3.9 has an elliptical shape with major and minor axes of approximately 1.°7 × 1.°1. From CHIPASS and S-PASS data, we calculate a spectral index α = −0.8 ± 0.2, consistent with synchrotron emission from an expanding shell in the radiative phase. The eROSITA data show an X-ray diffuse structure filling almost the entire radio shell. Based on our spectral analysis, we found the temperature to be approximately 0.6 keV and the column absorption density about 1021 cm−2. Comparing this absorption density to optical extinction maps, we estimated the distance to fall within the range of (1.0–1.7) kpc, considering the 1σ uncertainty range.

Active Learning for Deep Visual Tracking.

Convolutional neural networks (CNNs) have been successfully applied to the single target tracking task in recent years. Generally, training a deep CNN model requires numerous labeled training samples, and the number and quality of these samples directly affect the representational capability of the trained model. However, this approach is restrictive in practice, because manually labeling such a large number of training samples is time-consuming and prohibitively expensive. In this article, we propose an active learning method for deep visual tracking, which selects and annotates the unlabeled samples to train the deep CNN model. Under the guidance of active learning, the tracker based on the trained deep CNN model can achieve competitive tracking performance while reducing the labeling cost. More specifically, to ensure the diversity of selected samples, we propose an active learning method based on multiframe collaboration to select those training samples that should be and need to be annotated. Meanwhile, considering the representativeness of these selected samples, we adopt a nearest-neighbor discrimination method based on the average nearest-neighbor distance to screen isolated samples and low-quality samples. Therefore, the training samples' subset selected based on our method requires only a given budget to maintain the diversity and representativeness of the entire sample set. Furthermore, we adopt a Tversky loss to improve the bounding box estimation of our tracker, which can ensure that the tracker achieves more accurate target states. Extensive experimental results confirm that our active-learning-based tracker (ALT) achieves competitive tracking accuracy and speed compared with state-of-the-art trackers on the seven most challenging evaluation benchmarks. Project website: https://sites.google.com/view/altrack/.

Frictional Contacts Between Rough Grains With Fractal Morphology

AbstractSurface morphology plays a crucial role in friction between two contacting geomaterial surfaces, yet many questions remain unanswered regarding how detailed frictional responses deviate from analytical solutions for smooth surfaces due to the presence of roughness. In this study, we revisit the Cattaneo‐Mindlin problem for contacts between two fractally rough elastic or elasto‐plastic spheres generated based on ultra‐high degree (e.g., up to 2,000) spherical harmonics with the corresponding wavelength less than a thousandth of the mean grain diameter. Transverse contacts are simulated by finite element method, validated by the extended Cattaneo‐Mindlin solution to full slide regime for smooth sphere contacts. Extensive simulations are conducted to study contacts between two rough spheres with various surface geometries, micro friction coefficients, normal contact distances, relative roughness, fractal dimensions, and wavelength ranges. Out results indicate that: (a) the new analytical solution can approximately predict the macro contact response except for extremely high relative roughness and narrow wavelength range; (b) deviations induced by roughness from smooth sphere contacts can be neutralized by plasticity, high normal contact interference, and high micro friction coefficient; and (c) fractal dimension impacts frictional contacts less than relative roughness. The main cause of these phenomena can be credited to the underlying microscale contact information. Contact area and stress distributions and their evolutions provide concrete evidence of these observed behavior. This work provides a pathway for applying computational contact mechanics to many geophysical fields, such as the asperity model in earthquake science and the mechanics of granular materials.