Region Of Disk Research Articles

Effect of panretinal photocoagulation versus intravitreal bevacizumab injection on optic disc microcirculation in patients with diabetic retinopathy

BackgroundThis retrospective study aimed to compare optic disc vasculature changes in 1 and 3 months after treatment with either panretinal photocoagulation (PRP) or Intravitreal bevacizumab (IVB) in patients with diabetic retinopathy.MethodsA total of 50 eyes of 29 diabetic patients without severe complications were included in this comparative case series. Of these, twenty-eight eyes (15 patients) were assigned to the PRP group, while twenty-two eyes (14 patients) were treated with the biosimilar (IVB) (Stivant® CinnaGen Co., Iran). Optical tomography angiography (OCTA) was performed to measure optic disc vascular density (VD) as well as retinal nerve fiber layer (RNFL) thickness.ResultsThe mean age of the enrolled patients was 62.1 ± 8.3 years (40 to 78 years). During follow-up, whole disc VD, inside disc VD and peripapillary VD decreased significantly in the PRP group at month 1 (p = 0.032, p = 0.32, and p = 0.016, respectively) and month 3 (p = 0.004, p = 0.001 and p = 0.011, respectively). There was an insignificant and slight increase for these parameters in the IVB group. (p > 0.05 for all) A comparison of two treatment arms based on mean whole disc VD, inside disc VD, and peripapillary VD changes revealed a significant difference at month 1 (p = 0.009, p = 0.019, and p = 0.002, respectively) and month 3 (p = 0.002, p = 0.015, and p = 0.009, respectively). Peripapillary RNFL thickness increased in the PRP group at month 1 (p = 0.002) and then decreased at month 3 (p = 0.001). During three months of follow-up, the peripapillary RNFL thickness decreased significantly in the IVB group (p = 0.001). Peripapillary RNFL thickness changes were significantly different between treatment groups at month 1 and month 3. (p = 0.001 for both) The RNFL changes during the study did not significantly correlate with peripapillary VD changes in each group (p = 0.231 and p = 372, for PRP and IVB group, respectively).ConclusionThis study demonstrated that IVB and PRP treatments produced distinct short-term microvascular changes in the optic nerve of diabetic retinopathy patients. PRP treatment significantly reduced vascular density in the optic disc and peripapillary region over 3 months, with an initial increase in RNFL thickness followed by a decrease by month 3. In contrast, IVB treatment led to a slight increase in optic disc vascular density while significantly reducing RNFL thickness. No significant correlation was found between changes in RNFL thickness and peripapillary vascular density within either treatment group.

The effect of radiation pressure on the dispersal of photoevaporating discs

Abstract Observed IR excesses indicate that protoplanetary discs evolve slowly for the majority of their lifetime before losing their near- and mid-IR excesses on short timescales. Photoevaporation models can explain this ‘two-timescale’ nature of disc evolution through the removal of inner regions of discs after a few million years. However, they also predict the existence of a population of non-accreting discs with large cavities. Such discs are scarce within the observed population, suggesting the models are incomplete. We explore whether radiation-pressure-driven outflows are able to remove enough dust to fit observations. We simulate these outflows using cuDisc, including dust dynamics, growth/fragmentation, radiative transfer and a parameterisation of internal photoevaporation. We find that, in most cases, dust mass-loss rates are around 5-10 times too small to meet observational constraints. Particles are launched from the disc inner rim, however grains larger than around a micron do not escape in the outflow, meaning mass-loss rates are too low for the initial dust masses at gap-opening. Only systems that have smooth photoevaporation profiles with gas mass-loss rates >∼5 × 10−9 M⊙ yr−1 and disc dust masses <∼1 M⊕at the time of gap opening can meet observational constraints; in the current models these manifest as EUV winds driven by atypically large high-energy photon fluxes. We also find that the height of the disc’s photosphere is controlled by small grains in the outflow as opposed to shadowing from a hot inner rim; the effect of this can be seen in synthetic scattered light observations.

On the universality of star formation efficiency in galaxies

We analyze high-resolution hydrodynamics simulations of an isolated disk dwarf galaxy with an explicit model for unresolved turbulence and turbulence-based star formation prescription. We examine the characteristic values of the star formation efficiency per free-fall time, ϵff, and its variations with local environment properties, such as metallicity, UV flux, and surface density. We show that the star formation efficiency per free-fall time in ≈10 pc star-forming regions of the simulated disks has values in the range ϵff≈0.01−0.1, similar to observational estimates, with no trend with metallicity and only a weak trend with the UV flux. Likewise, estimated using projected patches of 500 pc size does not vary with metallicity and shows only a weak trend with average UV flux and gas surface density. The characteristic values of ϵff≈0.01−0.1 arise naturally in the simulations via the combined effect of dynamical gas compression and ensuing stellar feedback that injects thermal and turbulent energy. The compression and feedback regulate the virial parameter, αvir, in star-forming regions, limiting it to αvir≈3−10. Turbulence plays an important role in the universality of ϵff because turbulent energy and its dissipation are not sensitive to metallicity and UV flux that affect thermal energy. Our results indicate that the universality of observational estimates of ϵff can be plausibly explained by the turbulence-driven and feedback-regulated properties of star-forming regions.

Self-regulated growth of galaxy sizes along the star-forming main sequence

We present a systematic analysis of the spatially-resolved star formation histories (SFHs) using Hubble Space Telescope imaging data of ∼997, intermediate redshifts 0.5≤z≤2.0 galaxies from GOODS-S field, with stellar mass range 9.8≤logM⋆/M⊙≤11.5. We estimate the SFHs in three spatial regions (central region within the half-mass radii R50s, outskirts between 1−3R50s, and the whole galaxy) using pixel-by-pixel spectral-energy distribution (SED) fitting, assuming exponentially declining tau model in individual pixels. The reconstructed SFHs are then used to derive and compare the physical properties such as specific star-formation rates (sSFRs), mass-weighted ages (t 50), and the half mass-radii to get insights on the interplay between the structure and star-formation in galaxies. The correlation of sSFRs ratio of the centre and outskirts with the distance from the main sequence (MS) indicates that galaxies on the upper envelope of the MS tend to grow outside-in, building up their central regions, while those below the MS grow inside-out, with more active star-formation in the outskirts. The findings suggest a self-regulating process in galaxy size growth when they evolve along the MS. Our observations are consistent with galaxies growing their inner bulge and outer disc regions, where they appear to oscillate about the average MS in cycles of central gas compaction, which leads to bulge growth, and subsequent central depletion possibly due to feedback from the starburst resulting in more star formation towards the outskirts from newly accreted gas.

Water Enrichment from Pebble Drift in Disks with Gap-forming Planets

Volatiles like H2O are present as ice in solids in the cold outer regions of protoplanetary disks and as vapor in the warm inner regions within the water snow line. Icy pebbles drifting inwards from the outer disk sublimate after crossing the snow line, enriching the inner disk with solid mass and water vapor. Meanwhile, protoplanets forming within the disk open gaps in the disk gas, creating traps against the inward drift of pebbles and in turn reducing water enrichment in the inner disk. Recent disk observations from millimeter interferometry and infrared spectroscopy have supported this broad picture by finding a correlation between the outer radial distribution of pebbles and the properties of inner water vapor spectra. In this work, we aim at further informing previous and future observations by building on previous models to explore pebble drift in disks with multiple gaps. We systematically explore multiple gap locations and their depths (equivalent to the specific masses of planets forming within), and different particle sizes to study their impact on inner disk water enrichment. We find that the presence of close-in deep gaps carved by a Jupiter-mass planet is likely crucial for blocking icy pebble delivery into the inner disk, while planets with lower masses only provide leaky traps. We also find that disks with multiple gaps show lower vapor enrichment in the inner disk. Altogether, these model results support the idea that inner disk water delivery and planet formation are regulated by the mass and location of the most massive planets.

CC-TransXNet: a hybrid CNN-transformer network for automatic segmentation of optic cup and optic disk from fundus images.

Accurate segmentation of the optic disk (OD) and optic cup (OC) regions of the optic nerve head is a critical step in glaucoma diagnosis. Existing architectures based on convolutional neural networks (CNNs) still suffer from insufficient global information and poor generalization ability to small sample datasets. Besides, advanced transformer-based models, although capable of capturing global image features, perform poorly in medical image segmentation due to numerous parameters and insufficient local spatial information. To address the above two problems, we propose an innovative W-shaped hybrid network framework, CC-TransXNet, which combines the advantages of CNN and transformer. Firstly, by employing TransXNet and improved ResNet as feature extraction modules, the network considers local and global features to enhance its generalization ability. Secondly, the convolutional block attention module (CBAM) is introduced in the residual structure to improve the ability to recognize the OD and OC by applying attention in both the channel and spatial dimensions. Thirdly, the Contextual Attention (CoT) self-attention mechanism is used in the skip connection to adaptively allocate attention to the contextual information, further enhancing the segmentation's accuracy. We conducted experiments on four publicly available datasets (REFUGE 2, RIM-ONE DL, GAMMA, and Drishti-GS). Compared with the traditional U-Net, CNN, and transformer-based networks, our proposed CC-TransXNet improves the segmentation accuracy and significantly enhances the generalization ability on small datasets. Moreover, CC-TransXNet effectively controls the number of parameters in the model through optimized design to avoid the risk of overfitting, proving its potential for efficient segmentation.

Using the Ca ii Lines in T Tauri Stars to Infer the Abundance of Refractory Elements in the Innermost Disk Region

We present a study of the abundance of calcium in the innermost disk of 70 T Tauri stars in the star-forming regions of Chamaeleon I, Lupus, and Orion OB1b. We use calcium as a proxy for the refractory material that reaches the inner disk. We used magnetospheric accretion models to analyze the Ca ii emission lines and estimate abundances in the accretion flows of the stars, which feed from the inner disks. We find Ca depletion in disks of all three star-forming regions, with 57% of the sample having [Ca/H] < –0.30 relative to the solar abundance. All disks with cavities and/or substructures show depletion, consistent with trapping of refractories in pressure bumps. Significant Ca depletion ([Ca/H] < –0.30) is also measured in 60% of full disks, although some of those disks may have hidden substructures or cavities. We find no correlation between Ca abundance and stellar or disk parameters except for the mass accretion rate onto the star. This could suggest that the inner and outer disks are decoupled, and that the mass accretion rate is related to a mass reservoir in the inner disk, while refractory depletion reflects phenomena in the outer disk related to the presence of structure and forming planets. Our results of refractory depletion and timescales for depletion are qualitatively consistent with expectations of dust growth and radial drift, including partitioning of elements, and constitute direct evidence that radial drift of solids locked in pebbles takes place in disks.

Growth of amorphous ice grains by sintering in a protoplanetary disk

An icy grain in a protoplanetary nebula mainly consists of amorphous H2O ice and can grow through the migration of H2O molecules (sintering). The growth rate through sintering strongly depends on the diffusion constant of H2O molecules. I estimated the size of amorphous ice grains as a function of the sintering duration based on the diffusion constant of amorphous ice determined by the molecular dynamics simulation. It has been found that the growth proceeds in a wide disk region (∼20AU), and grain can grow to ∼10−3cm around the snowline. The growth of the icy grains can affect the evolution of the icy dust aggregates in a protoplanetary disk.

On the boundary-layer asymmetry in two-dimensional annular Rayleigh–Bénard convection subject to radial gravity

Radial unstable stratification is a potential source of turbulence in the cold regions of accretion disks. To investigate this thermal effect, here we focus on two-dimensional Rayleigh–Bénard convection in an annulus subject to radially dependent gravitational acceleration $g \propto 1/r$ . Next to the Rayleigh number $Ra$ and Prandtl number $Pr$ , the radius ratio $\eta$ , defined as the ratio of inner and outer cylinder radii, is a crucial parameter governing the flow dynamics. Using direct numerical simulations for $Pr=1$ and $Ra$ in the range from $10^7$ to $10^{10}$ , we explore how variations in $\eta$ influence the asymmetry in the flow field, particularly in the boundary layers. Our results show that in the studied parameter range, the flow is dominated by convective rolls and that the thermal boundary-layer (TBL) thickness ratio between the inner and outer boundaries varies as $\eta ^{1/2}$ . This scaling is attributed to the equality of velocity scales in the inner ( $u_i$ ) and outer ( $u_o$ ) regions. We further derive that the temperature drops in the inner and outer TBLs scale as $1/(1+\eta ^{1/2})$ and $\eta ^{1/2}/(1+\eta ^{1/2})$ , respectively. The scalings and the temperature drops are in perfect agreement with the numerical data.

Nuclear burning in an accretion flow around a stellar-mass black hole embedded within an AGN disc

ABSTRACT A stellar-mass black hole, embedded within the accretion disc of an active galactic nuclei (AGN), has the potential to accrete gas at a rate that can reach approximately ${\sim}10^9$ times the Eddington limit. This study explores the potential for nuclear burning in the rapidly accreting flow towards this black hole and studies how nucleosynthesis affects metal production. Using numerical methods, we have obtained the disc structure while considering nuclear burning and assessed the stability of the disc. In contrast to gas accretion onto the surface of a neutron star or white dwarf, the disc remains stable against the thermal and secular instabilities because advection cooling offsets the nuclear heating effects. The absence of a solid surface for a black hole prevents excessive mass accumulation in the inner disc region. Notably, nuclear fusion predominantly takes place in the inner disc region, resulting in substantial burning of $\rm ^{12}C$ and $\rm ^{3}He$, particularly for black holes around $M = 10\,{\rm M}_\odot$ with accretion rates exceeding approximately ${\sim}10^7$ times the Eddington rate. The ejection of carbon-depleted gas through outflows can lead to an increase in the mass ratio of oxygen or nitrogen to carbon, which may be reflected in observed line ratios such as N v/C iv and O iv/C iv. Consequently, these elevated spectral line ratios could be interpreted as indications of supersolar metallicity in the broad-line region.

Biomechanics of the intervertebral disc : Consequences of degenerative changes

The intervertebral disc represents the flexible connection between two adjacent vertebral bodies. Intervertebral discs, therefore, give the spine its enormous range of motion. At the same time, intervertebral discs distribute the load evenly over the bony vertebral bodies to ensure load transfer from the upper body to the pelvis, provide sufficient stability, and absorb shocks during everyday movements as well as under extreme loads. The two tissue regions of the intervertebral disc, the central fluid-rich core (nucleus pulposus) and the lamellae of the outer fibrous ring (annulus fibrosus) experience different stresses under load and movement. This article summarizes current knowledge on the biomechanical properties of the intervertebral disc and explains how these are altered by degeneration and which surgical treatment options for degenerated and herniated discs are advisable from abiomechanical perspective.

The Importance of Ambipolar Heating in the Standard Thin Accretion Disk with Outflows

This study examines the importance of the thermal effects of ambipolar diffusion (AD), by analyzing the governing properties in the middle and outer regions of a standard thin accretion disk with outflows. To accomplish this, we derive the nonideal magnetohydrodynamic equations, considering both the dynamical and thermal impacts of AD in these regions of the disk. In a stationary state, we utilize the self-similar technique to analyze the vertical structure of a disk with outflows and express the ambipolar diffusivity in terms of the Alfvén velocity and the Elsässer number. Our main focus is on the vertical temperature profile at large radii of the disk when the values of the Elsässer number are small. While the findings indicate that AD heating has minimal effects within the disk, it does play a critical role near the disk surface. When the Elsässer number is low, there is a notable rate of outflows and disk evaporation, resulting in angular momentum transport in these regions. This issue becomes important when we decrease the value of turbulent viscosity, as it leads to highlighting the AD heating effect. This allows the surface regions to become hotter and results in an increase in the drive of the outflows. The results of this research may be important for studying disk coronae and disk dispersal in the middle and outer regions of the thin accretion disk.

Self-consistent Disk-reflection Analysis of the Black Hole Candidate X-Ray Binary MAXI J1813−095 with NICER, Swift, Chandra, and NuSTAR

We present our analysis of MAXI J1813−095 during its hard state “stalled” outburst in 2018. This self-consistent analysis has been carried out using the Neutron Star Interior Composition Explorer, Swift, Chandra, and NuSTAR throughout seven observations of MAXI J1813−095. We find a relativistic iron line at ∼6.5 keV from the inner region of the accretion disk. Our results are consistent with a slightly truncated disk or nontruncated disk for an inner radius of ∼2R g and minimum spin of >0.7 with the best value of ∼0.9, assuming R in reaches the innermost stable circular orbit at L x ∼ 1% L Edd. We analyzed MAXI J1813−095 over its outburst, employing a spectral model that self-consistently couples the seed disk photons to the Comptonization and reflection components, also inclusive of reflection Comptonization. The unique aspect of this work is a reflection fraction of order unity, which is significantly higher than previous studies of this source and is a consequence of applying the self-consistent disk-Comptonization-reflection spectral model. Other key parameters, such as inclination and inner radius, are found to be consistent with other works.

Achieving Panoramic View Coverage in Visual Mobile Crowd-Sensing Networks for Emergency Monitoring Applications

Visual Mobile Crowd-Sensing(VMCS) collects photos by leveraging camera embedded in mobile users’ phones. There are two important issues in VMCS: determining whether photos collected by mobile users meet the requirements or not and designing an appropriate mechanism to attract mobile users to provide photos that meet the requirements. In this paper, we address those two issues when VMCS is applied to emergency monitoring applications. We first model an emergency scene as a disk region and define a coverage angle metric that quantifies the coverage ratio provided by each photo, and then formulate Maximize Coverage Angle under a Limited Budget(MCALB) problem. The goal of this paper is to recruit mobile users to provide panoramic view coverage for a disk while the total reward paid to participants does not exceed the budget. In our solution, we first propose a Coverage Angle Computation (CAC) algorithm to calculate the coverage angle of each uploaded photo. Then two incentive mechanisms: Guidance based Incentive Mechanism (GIM) and Coverage Prediction Incentive Mechanism (CPIM) are designed to encourage mobile users to upload photos with coverage angle that are not provided by other mobile users. Finally, we design a mobile app called I-share in android system to implement system. Meanwhile, we have recruited students to install I-share and simulated the information interaction between mobile users and server. We have conducted experiments by using I-share without/with embedded CAC algorithm to validate the efficiency of two incentive mechanisms. The experimental results demonstrate that our proposed incentive mechanisms effectively attract mobile users to provide panoramic view coverage of emergency scenes when the budget allows. Additionally, the CPIM outperforms the GIM, offering a higher coverage ratio with lower rewards.

The STRIPAK associated kinase MST4 is a novel mediator in heart failure pathogenesis

Abstract Heart failure still poses substantial challenges in understanding its underlying molecular pathways. We recently found the mammalian STE20-like kinase 4 (MST4) significantly upregulated in human failing hearts (5.7-fold in DCM and 3.8-fold ICM) as well as in heart failure animal models (i.e. 2.5-fold in Calsarcin-1-KO, 2.5-fold in MLP-KO). MST4 is a member of striatin interacting phosphatases and kinases complexes (STRIPAK), an emerging group of multiprotein complexes responsible for integrating cellular signalling pathways. We provide the first evidence of functional STRIPAK complexes containing MST4 by co-immunoprecipitation and interactomics experiments in cardiomyocytes. Moreover, we found MST4 to interact with several intercalated disc proteins like beta-Catenin or Desmin. Adenoviral overexpression of MST4 in neonatal rat ventricular cardiomyocytes (NRVCM) results in a significant increase in cell size (+13%). This was not accompanied by the activation of fetal genes such as NPPA, NPPB or RCAN1.4, but rather by an increase in phosphorylation of Protein kinase B (PKB/Akt, 3.3-fold). Akt is usually associated with physiological hypertrophy, indicating that MST4 may be involved in protective pathways in cardiomyocytes. In support of this notion, MST4 overexpression reduced apoptotic activity (cleavage of Caspase 3 -69%, Caspase 7 -80%, Parp1 -27%) and improved both contractility (fractional shortening cell +23%, fractional shortening sarcomere +30%, time to max. contraction cell -10%, time to max. contraction sarcomere -12%) and relaxation parameters (time to max. relaxation velocity cell -12%) in isolated adult rat ventricular cardiomyocytes. In order to identify cardiac targets of MST4, we performed a comprehensive analysis of the phosphoproteome of NRVCM overexpressing MST4 compared with control-virus +/- pharmacological inhibitor at two time points. We identified more than 70,000 peptides including more than 20,000 phosphopeptides in more than 4,000 protein groups. Using linear modelling with a reduced data set containing regulated features selected by thresholds for p-value and fold change, we observed a consistent MST4 effect and a number of enriched gene ontology terms. Here, we found several potential MST4 targets and effects on protein expression levels associated with intercalated disc proteins. In human heart samples, MST4 was also localized to the intercalated disc region by immunostaining. Interesting proteins in that context that might help explain some of the observed cardioprotective MST4 effects are Connexin 43, Desmin, Ryanodine receptor, Phospholemman, Junctophilin2, Myozap or Frizzled 1. Taken together, our data imply that MST4 upregulation in human heart failure serves an adaptive role which may offer translational opportunities.Graphical Abstract

Radial transport and nebular thermal processing of millimeter‐sized solids in the Solar protoplanetary disk inferred from Cr‐Ti‐O isotope systematics of chondrules

AbstractUnderstanding the material transport and mixing processes in the Solar protoplanetary disk provides important constraints on the origin of chemical and isotopic diversities of our planets. The limited extent of radial transport and mixing between the inner and outer Solar System has been suggested based on a fundamental isotopic dichotomy between non‐carbonaceous (NC) and carbonaceous (CC) meteorite groups. The limited transport and mixing could be further tested by tracing the formation regions of individual meteoritic components, such as Ca‐Al‐rich inclusions (CAIs) and chondrules. Here, we show further evidence for the outward transport of CAIs and chondrules from the inner and subsequent thermal processing in the outer region of the protoplanetary disk based on the petrography and combined Cr‐Ti‐O isotope systematics of chondrules from the Vigarano‐like (CV) carbonaceous chondrite Allende. One chondrule studied consists of an olivine core that exhibits NC‐like Ti and O, but CC‐like Cr isotopic signatures, which is enclosed by a pyroxene igneous rim with CC‐like O isotope ratios. These observations indicate that the olivine core formed in the inner Solar System. The olivine core then migrated into the outer Solar System and experienced nebular thermal processing that generated the pyroxene igneous rim. The nebular thermal processing would result in Cr isotope exchange between the olivine core and CC‐like materials, but secondary alteration effects on the parent body are also responsible for the CC‐like Cr isotope signature. By combining previously reported Cr‐Ti‐O isotope systematics of CV chondrules, we show that some CV chondrules larger than ~1 mm would have formed in the inner Solar System. The accretion of the millimeter‐sized, inner Solar System solids onto the CV carbonaceous chondrite parent body would require their very early migration into the outer Solar System within the first 1 million years after the Solar System formation.

Retrieval of Thermally Resolved Water Vapor Distributions in Disks Observed with JWST-MIRI

The mid-infrared water vapor emission spectrum provides a novel way to characterize the delivery of icy pebbles toward the innermost (<5 au) regions of planet-forming disks. Recently, JWST MIRI-MRS showed that compact disks exhibit an excess of low-energy water vapor emission relative to extended multigapped disks, suggesting that icy pebble drift is more efficient in the former. We carry out detailed emission-line modeling to retrieve the excitation conditions of rotational water vapor emission in a sample of four compact and three extended disks within the JWST Disk Infrared Spectral Chemistry Survey. We present two-temperature H2O slab model retrievals and, for the first time, constrain the spatial distribution of water vapor by fitting parametric radial temperature and column density profiles. Such models statistically outperform the two-temperature slab fits. We find a correlation between the observable hot water vapor mass and stellar mass accretion rate, as well as an anticorrelation between cold water vapor mass and submillimeter dust disk radius, confirming previously reported water line flux trends. We find that the mid-IR spectrum traces H2O with temperatures down to 180–300 K, but the coldest 150–170 K gas remains undetected. Furthermore the H2O temperature profiles are generally steeper and cooler than the expected “superheated” dust temperature in passive irradiated disks. The column density profiles are used to estimate icy pebble mass fluxes, which suggest that compact and extended disks may produce markedly distinct inner-disk exoplanet populations if local feeding mechanisms dominate their assembly.

Relativistic reflection modeling in AGN and related variability from PCA: a brief review

X-ray observations of active galactic nuclei (AGNs) reveal relativistic reflections from the innermost regions of accretion disks, which contain general-relativistic footprints caused by spinning supermassive black holes (SMBH). We anticipate the spin of a SMBH to be stable over the human timeframe, so brightness changes in the high-energy corona above the SMBH should slightly alter relativistic reflection. In this brief review, we discuss the latest developments in modeling relativistic reflection, as well as the rapid small variation in relativistic emission disclosed by the principal component analysis (PCA) of X-ray variability in AGN. PCA studies of X-ray spectra from AGNs have shown that relativistically blurred reflection has negligible fluctuations over the course of observations, which could originate from rapid (intrahour) intrinsic variations in near-horizon accretion flows and photon rings. The PCA technique is an effective way to disclose relativistic reflection from X-ray observations of AGNs, simplifying the complexity of largely variable X-ray data for automated spectral analysis with machine learning algorithms.

Probing the Disk Kinematics of M31 with DESI

M31’s stellar rotation curve and disk line-of-sight dispersion is presented using kinematic data from a novel DESI M31 survey in combination with similar datasets. After removing the foreground, the disk region is isolated and the velocity field deprojected. A flat ring model is fit to the velocity field of M31 out to 30 kpc using a maximum-likelihood routine. The stellar rotation curve is found to flatten to ∼220 km/s, and a disk line-of-sight velocity dispersion of ∼60 km/s is derived. The results extend M31’s rotation curve to 30 kpc and support the picture in which M31 has thicker disk than the Milky Way.

Robust integrated control of autonomous vehicles path following with response performance improvement considering lateral stability

In this paper, a robust integrated control scheme is developed for autonomous vehicles path following considering both yaw stability and roll stability. First, a controller with H∞ and optimal guaranteed cost performances is presented, and the poles of the closed-loop system are configured in a given disk region to improve the state response performance. The controller outputs front and rear wheel angles for path following, as well as an external yaw moment and an external roll moment for lateral stability control. Secondly, the braking forces acted on four wheels are optimally distributed by means of quadratic programing. Besides, the steering angles of the four wheels conform to the Ackermann geometry relation. Finally, the proposed control scheme is verified by CarSim/Simulink co-simulation, the results show that the scheme has better performance on path following accuracy and stability of yaw and roll. Meanwhile, constraining the poles in a given disk region can improve the state response performance of the vehicle during operation.