Average Distance Research Articles

Neoichnology of Rhinella dorbignyi (Bufonidae) burrows: improving the recognition and interpretation of toad burrows

A neoichnological characterization of toad burrows from organic-rich soils is presented in order to establish key ichnological signatures for their recognition in the geological record. Dorbigny’s Toad (Rhinella dorbignyi) produces J-shaped burrows with a single elliptical opening resembling the ichnogenus Macanopsis. The burrow varies from 15 to 20 cm in length and has a constant diameter along the shaft, enlarged in the chamber. The shaft is elliptical with a diameter of 2.5-3.0 cm in the major axis and 1.0–1.5 cm in the minor axis. The chamber is semicircular, with a distinct floor, and an average diameter of 5 cm in the major axis. A thick (3–5 mm), compacted, smooth, and uniform inorganic lining made of soil covers the burrow throughout its length. Surficial features, such as horizontal and vertical millimeter-scale striations and ridges, occur in the burrow surface and are produced by keratinized granules and spikes on the skin of R. dorbignyi. Those surficial features are generated during the toad’s movements inside the burrow as well as anchoring during ambush predation behavior. The main distinct features observed on the burrow surface are well-developed circular pit impressions produced by the keratinized tubercles present in the toad’s ankles during climbing activity. These characteristics encompass useful ichnotaxobases for recognition and distinguishing toad burrows from J-shaped, Macanopsis-like burrows produced by other soil-dwelling animals. The burrow architecture of R. dorbignyi suggests that J-shaped burrows are efficient structures for ambush predatory behavior in terrestrial ecosystems, as observed in spiders and scorpions.

Expression and significance of cystine transporter SLC7A11/xCT in early colorectal cancer specimens from endoscopic submucosal dissection.

The SLC7A11/xCT cystine transporter is intricately linked with ferroptosis. By mediating intracellular cystine flux, it regulates oxidative stress within neoplastic cells, thereby curtailing ferroptosis and influencing the emergence of colorectal cancer. This study aimed to gauge the SLC7A11/xCT expression across various tumorigenic stages in early colorectal adenocarcinoma tissues, shedding light on its specific role in the genesis of these early malignancies. Sixty specimens that underwent endoscopic submucosal dissection (ESD) resection with pathologic diagnosis of colorectal adenocarcinoma were collected. SLC7A11/xCT expression was pinpointed using immunohistochemistry, and correlations with the patients' clinical-pathological features were drawn. Additionally, a comprehensive bioinformatics assessment was undertaken to discern differential SLC7A11/xCT expressions across a spectrum of cancers. Immunohistochemical assessments unveiled a pronounced cytoplasmic SLC7A11/xCT expression, manifesting as a brownish-yellow hue, particularly in nascent colorectal cancer samples. Its expression was discernibly correlated with both patient gender and adenocarcinoma differentiation grade (P<0.05). Nevertheless, factors such as patient age, tumor localization, infiltration depth, diameter, adjacent adenoma histology, its major axis, and dysplasia degree bore no statistical significance with SLC7A11/xCT levels (P>0.05). Bioinformatics insights pointed to an upregulated SLC7A11/xCT expression across diverse malignancies, inclusive of colon adenocarcinoma, esophageal cancer, acute myeloid leukemia, lung squamous cell carcinoma, colorectal cancer, and endometrial cancer (P<0.05). Elevated SLC7A11/xCT expression marks early colorectal adenocarcinoma, with the intensity of this expression being intertwined with the patient's gender and the tumor's differentiation grade. It is postulated that colorectal cancer cells might amplify SLC7A11/xCT to stymie ferroptosis, thus fostering neoplastic proliferation, metastasis, and cellular stemness.

Multi-factor coupled forest fire model based on cellular automata

The risk of forest fires is substantial due to uneven precipitation distributions and abnormal climate change. This study employs cellular automata principles to analyze forest fire behavior, taking into account meteorological elements, combustible material types, and terrain slopes. The Wang Zhengfei model is utilized to compute fire spread speed, and a multifactor coupled forest fire model is developed. Comparisons with experimental data show a mean calculated fire spread speed of 0.69 m/min, which is consistent with the experimental results. Using the forest fire in Anning city, Yunnan Province, as a case study with a mean burned area of 2281 ha, the burned area, rate of change in burned area, and burning area demonstrated an increasing trend, with fluctuating states in the rate of change of the burning area. Employing the controlled variable method to examine forest fire spreading patterns under varying factors such as wind speed, vegetation type, and maximum slope reveals that under wind influence, the fire site adopts an elliptical shape with the downwind direction as the major axis. Quantitatively, when the wind speed increases from 2 m/s to 10 m/s, the burned area expands by a factor of 1.37. The ratio of the combustible material configuration coefficient to the burned area remains consistent across the different vegetation types, and the burned area increases by a factor of 1.92 when the maximum slope increases from 5° to 25°.

Quantitative classification evaluation model for tight sandstone reservoirs based on machine learning

Tight sandstone reservoirs are a primary focus of research on the geological exploration of petroleum. However, many reservoir classification criteria are of limited applicability due to the inherent strong heterogeneity and complex micropore structure of tight sandstone reservoirs. This investigation focused on the Chang 8 tight reservoir situated in the Jiyuan region of the Ordos Basin. High-pressure mercury intrusion experiments, casting thin sections, and scanning electron microscopy experiments were conducted. Image recognition technology was used to extract the pore shape parameters of each sample. Based on the above, through grey relational analysis (GRA), analytic hierarchy process (AHP), entropy weight method (EWM) and comprehensive weight method, the relationship index Q1 between initial productivity and high pressure mercury injection parameters and the relationship index Q2 between initial productivity and pore shape parameters are obtained by fitting. Then a dual-coupled comprehensive quantitative classification prediction model for tight sandstone reservoirs was developed based on pore structure and shape parameters. A quantitative classification study was conducted on the target reservoir, analyzing the correlation between reservoir quality and pore structure and shape parameters, leading to the proposal of favourable exploration areas. The research results showed that when Q1 ≥ 0.5 and Q2 ≥ 0.5, the reservoir was classified as type I. When Q1 > 0.7 and Q2 > 0.57, it was classified as type I1, indicating a high-yield reservoir. When 0.32 < Q1 < 0.47 and 0.44 < Q2 < 0.56, was classified as type II. When 0.1 < Q1 < 0.32 and 0.3 < Q2 < 0.44, it was classified as type III. Type I reservoirs exhibit a zigzag pattern in the northwest part of the study area. Thus, the northwest should be prioritized in actual exploration and development. Additionally, the initial productivity of tight sandstone reservoirs showed a positive correlation with the porosity, permeability, sorting coefficient, coefficient of variation, and median radius. Conversely, it demonstrated a negative correlation with the median pressure and displacement pressure. The perimeters of pores, their circularity, and the length of the major axis showed a positive correlation with the porosity, permeability, sorting coefficient, coefficient of variation, and median radius. On the other hand, they exhibited a negative correlation with the median pressure and displacement pressure. This study quantitatively constructed a new classification and evaluation system for tight sandstone reservoirs from the perspective of microscopic pore structure, achieving an overall model accuracy of 93.3%. This model effectively predicts and evaluates tight sandstone reservoirs. It provides new guidance for identifying favorable areas in the study region and other tight sandstone reservoirs.

Influence of planets on debris discs in star clusters – II. The impact of stellar density

ABSTRACT We present numerical simulations of planetary systems in star clusters with different initial stellar densities, to investigate the impact of the density on debris disc dynamics. We use lps+ to combine N-body codes nbody6++gpu and rebound for simulations. We simulate debris discs with and without a Jupiter-mass planet at 50 au, in star clusters with $N=$ 1k–64k stars. The spatial range of the remaining planetary systems decreases with increasing N. As cluster density increases, the planet’s influence range first increases and then decreases. For debris particles escaping from planetary systems, the probability of their direct ejection from the star cluster decreases as their initial semimajor axis ($a_0$) or the cluster density increases. The eccentricity and inclination of surviving particles increase as cluster density increases. The presence of a planet leads to lower eccentricities and inclinations of surviving particles. The radial density distribution of the remaining discs decays exponentially in sparse clusters. We derive a general expression of the gravitational encounter rate. Our results are unable to directly explain the scarcity of debris discs in star clusters. Nevertheless, given that many planetary systems have multiple planets, the mechanism of the planet-cluster combined gravitational influence on the disc remains appealing as a potential explanation.

Flexible Bridge-Conic Strategies for Moon-to-Moon Analytical Transfer Design

The multi-burn transfer framework based on the moon-to-moon analytical transfer method allows rapid patching of low-energy trajectories in the vicinity of different moons in a planetary system. However, the semimajor axis and eccentricity of intermediate arcs of one transfer mission are fixed in the existent multi-burn strategies. Additional propellant consumption is required to enable the transfers at all departure epochs, and a nonanalytical formulation still remains for transferring to spatial periodic orbits. To address these difficulties, new multi-burn strategies with variable intermediate arcs are proposed to meet the transfer conditions for different types of arrival orbits. Specifically, one or two intermediate arcs with one variable parameter are introduced and can be determined analytically. In numerical simulations, the proposed flexible bridge-conic strategies are applied to design transfers between libration point orbits in both the Jovian and Saturnian systems. Final results validate the effectiveness of the proposed strategies and indicate the important advantage in propellant saving compared with the existent multi-burn strategies.

Ultraconfined oblate hard particles between hybrid penetrable walls.

We have investigated, by Monte Carlo simulation, the orientational structure of very thin films of a discotic liquid crystal (DLC) confined between hybrid walls of controllable penetrability, as a function of wall separation L_{z}. Our purpose was to clarify whether, as predicted by continuum theory, the preferred orientation of the DLC is uniform, changes linearly, or changes discontinuously, when L_{z} and the anchoring strengths at either wall are changed. The model consists of oblate hard Gaussian overlap (HGO) particles: each wall sees a particle as a disk of zero thickness and diameter D less than or equal to that of the actual particle σ_{0}, embedded inside the particle and located halfway along, and perpendicular to, its minor axis. This provides a particle-level mechanism to control the anchoring properties of the walls, from planar (edge-on) for D∼0 to homeotropic (face-on) for D∼σ_{0}, which can be done independently at either wall. As in our earlier work [C. Anquetil-Deck et al., J. Phys. Chem. B 124, 7709 (2020)1520-610610.1021/acs.jpcb.0c05027], which was restricted to L_{z}=6σ_{0}, depending on the values of D_{s}≡D/σ_{0} at the top (D_{s}^{t}) and bottom (D_{s}^{b}) walls, we find domains in (D_{s}^{b},D_{s}^{t}) space in which particle alignment is uniform planar (UP), uniform homeotropic (UH), or varies linearly from planar at one wall to homeotropic at the other (L), but no bistable or tristable regions are identified between these domains. Most importantly, there appears never to occur an abrupt change of the LC orientation when the walls strongly favor different anchorings, in general agreement with the scenario proposed by Velasco and co-workers [D. de las Heras et al., Phys. Rev. E 79, 011712 (2009)1539-375510.1103/PhysRevE.79.011712], but in contrast to the behavior of equivalent calamitic systems [F. Barmes et al., Phys. Rev. E 69, 061705 (2004)1539-375510.1103/PhysRevE.69.061705; Phys. Rev. E, 71, 021705 (2005)1539-375510.1103/PhysRevE.71.021705; C. Anquetil-Deck et al., Phys. Rev. E 86, 041707 (2012)1539-375510.1103/PhysRevE.86.041707]. However, for the thinnest films investigated (L_{z}=2σ_{0}), the system is unable to accommodate a rotation of the preferred particle orientation from one wall to the other and adopts instead a tilted configuration, similar to that reported earlier for Gay-Berne films in symmetric confinement [T. Gruhn et al., Thin Solid Films 330, 46 (1998)0040-609010.1016/S0040-6090(98)00799-8; Mol. Phys. 93, 681 (1998)10.1080/002689798169014] but which, as far as we know, has been missed in most earlier work.

Triton’s Captured Youth: Tidal Heating Kept Triton Warm and Active for Billions of Years

Neptune’s moon Triton has two remarkable attributes: its retrograde orbit suggests that it was captured from the Kuiper Belt, and Triton has one of the youngest surfaces of all the icy satellites in the solar system. Soon after capture, Triton experienced strong diurnal tides raised by Neptune, which caused intense deformation, heating, and melting of its ice shell as its highly eccentric initial orbit was circularized. While previous studies have suggested that Triton’s orbit would have circularized early in solar system history, we show that internal feedbacks between tidal heating and ice shell melting significantly reduce the orbital evolution rate, causing strong tidal heating to persist for billions of years. We simulate Triton’s post-capture evolution over a range of initial semimajor axes and ice shell properties. We find that Triton’s ice shell would have been extremely thin (1–10 km) for a period of 1–4 billion years, with tidal stresses strong enough to fracture the entire ice shell down to the subsurface ocean. A final phase of intense geologic activity may have occurred after tidal dissipation waned, in which late-stage ice shell thickening caused ocean pressurization potentially sufficient to refracture the ice shell and push water to the surface. Such overpressurization could have caused recent massive cryovolcanic resurfacing, perhaps explaining Triton’s geologically young surface. It is therefore possible that Triton’s youthful surface and its origin as a captured satellite may in fact be related. A long-lived subsurface ocean and extended thin ice shell period also greatly increase Triton’s astrobiological potential.

329. PREDICTION OF MEDIASTINAL LYMPH NODE METASTASIS IN SIEWERT TYPE I/II ESOPHAGOGASTRIC JUNCTION CANCER WITH ESOPHAGEAL INVASION

Abstract Background Mediastinal lymph node dissection (LND) is a critical factor to decide the surgical strategy for Esophagogastric junction (EGJ) cancers. As a result of a prospective multicenter study in Japan, surgical algorithm including the extent of LND for EGJ cancers has recently been proposed according to the length of esophageal invasion. However, preoperative measure predicting upper mediastinal LN metastasis is still lacking, and the oncologic efficacy of mediastinal LND remain unknown. Methods The aim of this study was to identify preoperative factors predicting mediastinal LN metastasis, and we hypothesized that preoperative CT image would be of utility. Patients who underwent surgical treatment for Siewert Type I/II EGJ cancer with esophageal invasion with curative intent between 2000 and 2022 at the Tokai University Hospital were retrospectively reviewed. Results A total of 103 patients were enrolled. Among them, 55, 74, and 74 patients underwent upper, middle, and lower mediastinal LND, respectively. Upper/middle/lower mediastinal LN metastasis was observed in 14/13/23 of those patients, respectively, with lower thoracic paraesophageal LNs (29%), middle thoracic paraesophageal LNs (18%), and right recurrent nerve LNs (16%) being the three most common metastatic sites. Estimated invasion depth of the primary lesion≧cT3 (p≦0.007), tumor size≧4cm (p≦0.002), esophageal invasion length≧4cm (p≦0.007) and minor axis of the LN≧5mm by preoperative CT image (p&amp;lt;0.001) were significant preoperative factors related to mediastinal LN metastasis. Conclusion Clinical T factor, tumor size, the size of mediastinal LN by CT image, as well as esophageal invasion length, were important preoperative factors to predict mediastinal LN metastasis, and those factors should be taken into consideration to decide the surgical strategy for EGJ cancers with esophageal invasion. Survival impact of mediastinal LND still remain unclear, and further accumulation of cases and prospective studies are awaited.

Relation between the geometric shape and rotation of Galactic globular clusters

We homogeneously measured the elliptical shapes of 163 globular clusters (GCs) using the on-sky distribution of their cluster members and the third data release of the ESA mission Gaia (DR3). The astrometry enables the differentiation of stars within clusters from those in the field. This feature is particularly valuable for clusters located in densely populated areas of the sky, where conventional methods for measuring the geometry of the GCs are not applicable. The median axial ratio of our full sample is 〈b/a〉 = 0.935−0.090+0.033 and 0.986−0.004+0.009 for the subset of 11 GCs previously studied based on Hubble Space Telescope imaging. We investigated whether the minor axis of the ellipses can be interpreted as a pseudo-rotation axis by comparing it to measurements of cluster rotation. Using the radial velocities from Gaia, we detected rotation for three clusters, NGC 5139, NGC 104, and NGC 6341, and observed an alignment between the pseudo-rotation axis and the 2D projection of the real rotation axis. To expand the set of clusters for which rotation has been detected, we analyzed multiple literature references. Depending on the reference used for comparison, we observed an alignment in between 76% to 100% of the clusters. The lack of an alignment observed in some clusters may be linked to different scales analyzed in various studies. Several studies have demonstrated that the orientation of rotation varies with the distance from the center. We estimate that the next Gaia release will increase the number of stars with radial velocities in GCs from ~10 000 in Gaia DR3 to ~55 000 in Gaia DR4. This will enable the measurement of rotation and ellipticities at identical angular scales for additional clusters, which will help us to clarify whether the previously mentioned alignment occurs in all clusters.

The ALMA-CRISTAL survey

Massive star-forming galaxies in the high-redshift universe host large reservoirs of cold gas in their circumgalactic medium (CGM). Traditionally, these reservoirs have been linked to diffuse H I Lyman-α (Lyα) emission extending beyond ≈10 kpc scales. In recent years, millimeter and submillimeter observations have started to identify even colder gas in the CGM through molecular and/or atomic tracers such as the [C II] 158 μm transition. In this context, we studied the well-known J1000+0234 system at z = 4.54 that hosts a massive dusty star-forming galaxy (DSFG), a UV-bright companion, and a Lyα blob. We combined new ALMA [C II] line observations taken by the CRISTAL survey with data from previous programs targeting the J1000+0234 system, and achieved a deep view into a DSFG and its rich environment at a 0″​​​. 2 = 1.3 kpc resolution. We identified an elongated [C II]-emitting structure with a projected size of 15 kpc stemming from the bright DSFG at the center of the field, with no clear counterpart at any other wavelength. The plume is oriented ≈40° away from the minor axis of the DSFG, and shows significant spatial variation of its spectral parameters. In particular, the [C II] emission shifts from 180 km s−1 to 400 km s−1 between the bottom and top of the plume, relative to the DSFG’s systemic velocity. At the same time, the line width starts at 400 − 600 km s−1 but narrows down to 190 km s−1 at the top end of the plume. We discuss four possible scenarios to interpret the [C II] plume: a conical outflow, a cold accretion stream, ram pressure stripping, and gravitational interactions. While we cannot strongly rule out any of these with the available data, we disfavor the ram pressure stripping scenario due to the requirement of special hydrodynamic conditions.

Time–energy distribution of photoelectron from atomic states with different magnetic quantum numbers in elliptically polarized laser fields

Abstract A Wigner-distribution-like (WDL) function based on the strong-field approximation (SFA) theory is used to investigate the ionization time of the photoelectron emitted from the initial states with different magnetic quantum number m in elliptically polarized electric fields. The saddle-point method is adopted for comparisons. For different m states, a discrepancy exists in the WDL distributions of the photoelectrons emitted in a direction close to the major axis of the laser field ellipse. Based on the saddle-point analysis, this discrepancy can be ascribed to the interference between electrons ionized from two tunneling instants. Our results show that the relationships between the tunneling instants and kinetic energy of photoelectrons are the same for different m initial states when the Coulomb potential is not considered. Our work sheds some light on the ionization-time information of electrons from different magnetic quantum states.

A Detailed Analysis of a Magnetic Island Observed by WISPR on Parker Solar Probe

We present the identification and physical analysis of a possible magnetic island feature seen in white-light images observed by the Wide-field Imager for Solar Probe (WISPR) on board the Parker Solar Probe. The island is imaged by WISPR during Parker's second solar encounter on 2019 April 6, when Parker was ∼38 R ⊙ from the Sun's center. We report that the average velocity and acceleration of the feature are approximately 334 km s−1 and −0.64 m s−2. The kinematics of the island feature, coupled with its direction of propagation, indicate that the island is likely entrained in the slow solar wind. The island is elliptical in shape with a density deficit in its center, suggesting the presence of a magnetic guide field. We argue that this feature is consistent with the formation of this island via reconnection in the current sheet of the streamer. The feature's aspect ratio (calculated as the ratio of its minor to major axis) evolves from an elliptical to a more circular shape that approximately doubles during its propagation through WISPR’s field of view. The island is not distinct in other white-light observations from the Solar and Heliospheric Observatory and the Solar Terrestrial Relations Observatory coronagraphs, suggesting that this is a comparatively faint heliospheric feature and that viewing perspective and WISPR’s enhanced sensitivity are key to observing the magnetic island.

Bright unintended electromagnetic radiation from second-generation Starlink satellites

We report on the detection of unintended electromagnetic radiation (UEMR) from the second-generation of Starlink satellites. Observations with the LOFAR radio telescope between 10 to 88 MHz and 110 to 188 MHz show broadband emission covering the frequency ranges from 40 to 70 MHz and 110 to 188 MHz from the v2-Mini and v2-Mini Direct-to-Cell Starlink satellites. The spectral power flux density of this broadband UEMR varies from satellite to satellite, with values ranging from 15 to 1300 Jy, between 56 and 66 MHz, and from 2 to 100 Jy over two distinct 8 MHz frequency ranges centered at 120 and 161 MHz. We compared the detected power flux densities of this UEMR to that emitted by the first generation v1.0 and v1.5 Starlink satellites. When correcting for the observed satellite distances, we find that the second-generation satellites emit UEMR that is up to a factor of 32 stronger compared to the first generation. The calculated electric field strengths of the detected UEMR exceed typical electromagnetic compatibility standards used for commercial electronic devices as well as recommended emission thresholds from the Radiocommunication Sector of the International Telecommunications Union (ITU-R) aimed at protecting the 150.05–153 MHz frequency range allocated to radio astronomy. We characterize the properties of the detected UEMR with the aim of assisting the satellite operator with the identification of the cause of the UEMR.

삼국~통일신라시대 瓦棺墓에 대한 新고찰

Humanity chose ‘a tomb’ as the time after life, that is, a space to face death. In other words, a tomb is a space where people spend longer than life, and among them, a tomb made of tile used as a building material can be called a Tile Coffin Tombs. Until now, tiled coffin tombs have not received much attention in academia, but recent research cases are increasing. Accordingly, after conducting a survey on the current status, the size and longitudinal ratio of the tomb, the location and direction of the major axis, type classification and year, and burial products and burial patterns were examined. Through this, it was confirmed that there are not a few differences betweenthe tiled tombs of Baekje and Silla cultures. In addition, we looked at the case of China, where Tile Coffin Tombs was first created, and the social image of the Wei, jin, Northern and Southern dynasties in which Tile Coffin Tombs appeared in Baekje. As a result, it was confirmed that Baekje, which had a close relationship with the Chinese Southern Dynasties, continued to exchange technologies in various fields of society and received Buddhism and temples, half-down draft kiln, and new roof tile production techniques. In the process, it was confirmed that the tiled coffin tomb that was introduced into Baekje was later transmitted to Silla, and that through re-localization, the tiled coffin tomb of the two cultures came to be established in different forms. The nature of burial in tile-coffin tombs, which were originally mainly used as infant graves in China, must also be understood in conjunction with these changes and need to be interpreted from a broad perspective.

Decadal evolution of GPS, GLONASS, and Galileo mean orbital elements

We examine the decadal evolution of GPS, GLONASS, and Galileo satellite orbital elements, including the semi-major axis, inclination, eccentricity, right ascension of the ascending node, and the argument of perigee. We focus on the long-term changes in Keplerian elements by averaging them over several complete revolutions forming mean orbital elements giving an explanation of the main perturbing forces for each Keplerian parameter. The combined International GNSS Service (IGS) orbits are employed which were derived in the framework of IGS Repro3 for ITRF2020 preparation spanning eight years from 2013 to 2021. The semi-major axis for GPS satellites is affected by a strong resonance with Earth’s gravity field resulting in a long-period perturbation similar to a secular drift. The semi-major axes of Galileo and GLONASS do not show any large-scale rates, however, Galileo satellites are affected by the Y-bias resulting in semi-major axis drifts. A significant perturbations due to solar radiation pressure affect the semi-major axis, eccentricity, and the argument of perigee. Notably, for Galileo satellites in eccentric orbits, the signal with a one-draconitic year is evident in the semi-major axis. The evolution of the mean right ascension of the ascending node and argument of perigee is primarily characterized by nearly linear regression mainly due to even zonal harmonics of the Earth’s gravity field. The long-term evolution of eccentricity and inclination does not follow a linear trend but exhibits clear oscillations dependent on the secular drift of the right ascension of the ascending node (for inclination) or the argument of perigee (for eccentricity). Additionally, the long-term perturbation of inclination reaches its maximum when the absolute value of the Sun’s elevation angle above the orbital plane (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document} angle) is at its minimum, while the eccentricity reaches its minimum simultaneously with the minimum of the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document} angle.

Bipolar Blobs as Evidence of Hidden AGN Activities in the Low-mass Galaxies

We report evidence of a hidden black hole (BH) in a low-mass galaxy, MaNGA 9885-9102, and provide a new method to identify active BHs in low-mass galaxies. This galaxy is originally selected from the MaNGA survey with distinctive bipolar Hα blobs at the minor axis. The bipolar feature can be associated with active galactic nuclei (AGN) activity, while the two blobs are classified as the H ii regions on the BPT diagram, making the origins confusing. The Swift UV continuum shows that the two blobs do not have UV counterparts, suggesting that the source of ionization is out of the blobs. Consistent with this, the detailed photoionization models prefer AGN rather than the star-forming origin with a significance of 5.8σ. The estimated BH mass is M BH ∼ 7.2 × 105 M ⊙ from the M BH–σ * relationship. This work introduces a novel method for detecting the light echo of BHs, potentially extending to intermediate mass, in low-metallicity environments where the traditional BPT diagram fails.

Controlling sonic rectangular jet with nozzle trailing edge modification

Sonic rectangular jet emanating from a convergent nozzle of aspect ratio 2 with modified trailing edge in the form of triangular extension on its widest side is investigated experimentally at different nozzle pressure ratios corresponding to underexpanded states of sonic jet. To assess the impact of trailing edge modification on jet mixing, the sonic rectangular jet from aspect ratio two plain convergent nozzle (without trailing edge modification) is also studied. The centerline pressure decay results at nozzle pressure ratios 2, 3, 4 and 5 confirm the superiority of modified jet (jet from trailing edge modified nozzle) over plain jet from the mixing point of view. At all the pressure ratios, the modified jet possessed shorter core and weaker shock and expansion waves compared to plain jet, which is an outcome of faster mixing of modified jet with ambient fluid. The enhanced mixing caused the modified jet to decay faster than the plain jet. An appreciable core length reduction of about 32% is noticed at pressure ratio of 5. The modified jet experienced increased spread along major axis than along minor axis owing to the restriction offered by the triangular extension on jet spread along minor axis. Thus, the axis switching was absent in modified jet compared to plain jet switching axes at all pressure ratios. The shadowgraph images confirmed the presence of weaker waves in the modified jet. Also, the images confirmed the absence of Mach disk in the modified jet at pressure ratio of 5 compared to plain jet.

A single-cell atlas of spatial and temporal gene expression in the mouse cranial neural plate.

The formation of the mammalian brain requires regionalization and morphogenesis of the cranial neural plate, which transforms from an epithelial sheet into a closed tube that provides the structural foundation for neural patterning and circuit formation. Sonic hedgehog (SHH) signaling is important for cranial neural plate patterning and closure, but the transcriptional changes that give rise to the spatially regulated cell fates and behaviors that build the cranial neural tube have not been systematically analyzed. Here we used single-cell RNA sequencing to generate an atlas of gene expression at six consecutive stages of cranial neural tube closure in the mouse embryo. Ordering transcriptional profiles relative to the major axes of gene expression predicted spatially regulated expression of 870 genes along the anterior-posterior and mediolateral axes of the cranial neural plate and reproduced known expression patterns with over 85% accuracy. Single-cell RNA sequencing of embryos with activated SHH signaling revealed distinct SHH-regulated transcriptional programs in the developing forebrain, midbrain, and hindbrain, suggesting a complex interplay between anterior-posterior and mediolateral patterning systems. These results define a spatiotemporally resolved map of gene expression during cranial neural tube closure and provide a resource for investigating the transcriptional events that drive early mammalian brain development.

Impact of vegetation albedo on the habitability of Earth-like exoplanets

ABSTRACT Vegetation can modify the planetary surface albedo via the Charney mechanism, as plants are usually darker than the bare surface of the continents. We updated ESTM (Earth-like surface temperature model) to incorporate the presence, distribution and evolution of two dynamically competing vegetation types that resemble grasslands and trees (the latter in the double stages of life: adults and seedlings). The newly developed model was applied to estimate how the climate-vegetation system reaches equilibrium across different rocky planetary configurations, and to assess its impact on temperature and habitability. With respect to a world with bare granite continents, the effect of vegetation-albedo feedback is to increase the average surface temperature. Since grasses and trees exhibit different albedos, they affect temperature to different degrees. The ultimate impact on climate depends on the outcome of the competition between these vegetation types. The change in albedo due to vegetation extends the habitable zone and enhances the overall planetary habitability beyond its traditional outer edge. This effect is especially relevant for planets that have a larger extension of continents than Earth. For Earth, the semimajor axis d = 1.04 au represents the turning point where vegetation enhances habitability from h = 0.0 to 0.485 (in the grass-dominance case), to h = 0.584 (in the case of coexistence between grasses and trees), and to h = 0.612 (in the tree-dominance case). This illustrates the transition from a snowball state to a planet with intermediate habitability at the outer edge of the circumstellar habitability zone.