Stages Of Evolution Research Articles

An initial model construction method constrained by stratigraphic sequence representation for pre‐stack seismic inversion

AbstractThe construction of an accurate and high‐resolution reservoir parameter model is crucial for reservoir characterization. However, due to the band‐limited characteristics of seismic data, the inversion results heavily rely on the accuracy of the initial model. Most existing techniques for constructing an initial model interpolate well logging data within the stratigraphic framework, neglecting the effect of the stratigraphic sequence, which compromises the reliability of the initial model. The stratigraphic sequence is essential for dividing stratigraphic evolution stages and defining a geological relationship between reservoirs within the stratigraphic framework. Therefore, an initial model construction method constrained by stratigraphic sequence representation is proposed for pre‐stack seismic inversion. The process begins with establishing the stratigraphic framework using horizon and fault data. Subsequently, the collaborative sparse representation algorithm is used to learn a joint dictionary that captures the relationship of structural features between seismic data and stratigraphic sequence from the well logging data. In the process of seismic data representation, the stratigraphic sequence is accurately represented in three‐dimensional space by sharing sparse coefficients in the joint dictionary. Finally, the elastic parameter model is constructed by integrating the stratigraphic framework, stratigraphic sequence and well logging data, providing a reliable initial model for pre‐stack seismic inversion. The main innovation of the proposed method is the three‐dimensional representation of the stratigraphic sequence. A synthetic example demonstrates that the proposed method produces a more accurate initial model than conventional interpolation methods. Additionally, when applied to field data, it yields satisfactory results even without complete S‐wave velocity well logging data.

Is Cancer Metabolism an Atavism?

The atavistic theory of cancer posits that cancer emerges and progresses through the reversion of cellular phenotypes to more ancestral types with genomic and epigenetic changes deactivating recently evolved genetic modules and activating ancient survival mechanisms. This theory aims at explaining the known cancer hallmarks and the paradox of cancer's predictable progression despite the randomness of genetic mutations. Lineweaver and colleagues recently proposed the Serial Atavism Model (SAM), an enhanced version of the atavistic theory, which suggests that cancer progression involves multiple atavistic reversions where cells regress through evolutionary stages, losing recently evolved traits first and reactivating primitive ones later. The Warburg effect, where cancer cells upregulate glycolysis and lactate production in the presence of oxygen instead of using oxidative phosphorylation, is one of the key feature of the SAM. It is associated with the metabolism of ancient cells living on Earth before the oxygenation of the atmosphere. This review addresses the question of whether cancer metabolism can be considered as an atavistic reversion. By analyzing several known characteristics of cancer metabolism, we reach the conclusion that this version of the atavistic theory does not provide an adequate conceptual frame for cancer research. Cancer metabolism spans a whole spectrum of metabolic states which cannot be fully explained by a sequential reversion to an ancient state. Moreover, we interrogate the nature of cancer metabolism and discuss its characteristics within the framework of the SAM.

Soil phosphorus fraction and availability dynamics along a 2-million-year soil chronosequence in northern Hainan Island, China

The low phosphorus (P) content and availability in highly weathered tropical soils may limit ecosystem service and function. However, information on P fraction dynamics and availability during tropical soil development is scarce. Understanding P transformations and their impacts on P availability at various stages of tropical soil evolution is crucial for effective nutrient management strategies. In this study, a soil chronosequence (ranging from 0.09to 2.30 million years) was combined with the sequential P extraction to assess temporal changes in P fractions with soil age in northern Hainan Island, China. Results showed that total P (TP) content increased initially (<0.146-million-year), declined at the 0.64- million-year site, and then rebounded (>1.12-million-year) as soil age increased. Sequential P extraction revealed that the stable P pools, including concentrated HCl extracted P and residual-P, were the dominant P fractions, mirroring the temporal trend of TP. The labile NaHCO3-Pi concentration, which reflects soil P availability, ranged from 2.29 to 5.63 mg kg−1. Despite the low labile P content, it is sufficient to meet plant P requirements, even in the oldest soil. Structural equation modeling indicated that moderately labile NaOH-Pi and the stable P pools significantly influenced soil P availability, together explained 51.0 % of the variation in labile P. This study elucidates the pattern of P transformation during tropical pedogenesis over a 2.30-million-year timescale, highlighting the substantial contribution of stable P pools to P supply in tropical soils with low labile P content.

A population of mid-infrared large-amplitude variable young stellar objects from unTimely

ABSTRACT Utilizing a decade-long unTimely data set, supplemented by multiband data from archives, we search for young stellar objects (YSOs) with variations larger than one magnitude in W1 band within a region of 110 square degrees in the Galactic plane, covered by VISTA Variables in the Via Lactea. A total of 641 candidate YSOs have been identified. We classified them into bursts, dips, faders, seculars, and irregulars. Within the burst category, 18 sources were identified as FUor candidates and 1 as an EXor candidate. Irregulars are the most prevalent in the sample. In both bursts and faders, the redder sources tend to show a pattern of bluer when brighter, whereas the bluer sources display the opposite trend, possibly related to the accretion structure of YSOs at different stages. Finally, we obtained the recurrence time-scale for FUor eruptions at various stages of YSO evolution. Our findings indicate that younger YSOs generally experience more frequent eruptions compared to older ones.

Tracing the evolutionary leaps and boundaries of digital platforms: a case study of Facebook

ABSTRACT Digital platforms exert a significant influence on the creation and utilisation of products and services across the globe. Past research has shed light on digital platform establishment, strategies for growing platforms’ scale and scope, as well as the role of boundary resources in stimulating third-party development. However, we lack insight into the interaction of growth in scale and scope as traditional digital solutions are transformed into emergent platforms, and how such platforms over time evolve beyond the platform metaphor. .In this paper, we seek to understand the emergence, evolution, and boundaries of digital platforms over time through a longitudinal case study of Facebook. For this, we utilise Facebook’s publicly available documentation of its evolution as digital trace data. We discover that from 2004 to 2019, Facebook underwent four distinct evolutionary stages: interaction, integration, interconnection, and implantation. These stages were facilitated by two novel roles for digital platform boundary resources that we term as distributing and centring. Based on these findings, we theorize the role of digital artefacts’ material qualities in their evolution from applications, via platforms, to information infrastructures. The paper contributes a model explicating this traversal as well as the subsequent unbundling to a new entity repeating the same traversal.

ACD-DE: An adaptive cluster division Differential Evolution for mitigating population diversity deficiency

Differential Evolution (DE) is a simple but powerful population based evolutionary algorithm, which was widely used to solve various complex optimization problems. However, even recently proposed state-of-the-art DE variants tend to get trapped in local minima due to insufficient population diversity in the later stages of evolution. In this paper, an Adaptive Cluster Division Differential Evolution (ACD-DE) algorithm was proposed to mitigate population diversity deficiency. The main highlights are summarized as follows: Firstly, a novel cluster division based mutation strategy was proposed to enhance the diversity of difference vectors during the mutation operation. Secondly, a population diversity detection indicator was used to assess the stagnation level of individuals, enabling stagnation management to be launched based on different stagnation levels. Thirdly, an effective evolution guidance mechanism was proposed by adjusting certain parameters in the D-dimensional vectors of outlier individuals that significantly deviate from the current population. Fourthly, novel parameter adaptations were employed to dynamically adjust the control parameters, including the scale factor F, crossover rate CR, and population size PS, during evolution. To validate the ACD-DE algorithm, extensive experiments were conducted on 88 benchmark functions from the CEC2013, CEC2014, and CEC2017 test suites, focusing on the optimization accuracy, convergence speed, time complexity, and component effectiveness. The results demonstrate the superiority of our ACD-DE algorithm compared to state-of-the-art DE variants.

The Technology of Cooking in the British Isles, 1600 to 1950 - Part II

In the first part of her article (in PPC 1), Caroline Cookson suggested that cooking methods went through five evolutionary stages, and dealt with stages One, the open fire, Two, the 'open' range, and Three, the 'closed' range. She now considers stages Four and Five. Comments from readers will be warmly appreciated, especially if they help to resolve any of the questions posed at the end.

Asteroseismology of the fast-rotating high-amplitude δ Scuti star V2367 Cygni

ABSTRACT We present the comprehensive analysis of the high-amplitude $\delta$ Sct star V2367 Cygni. First, we perform the frequency analysis for the whole available set of the Kepler and TESS photometry. Most of the frequency peaks are harmonics or combinations of the three known independent frequencies with the highest amplitudes, i.e.$\nu _1=5.661\,06$ d$^{-1}$, $\nu _2=7.14898$ d$^{-1}$, and $\nu _3=7.77557$ d$^{-1}$. The total number of independent frequencies is 26 and 25 from the Kepler and TESS light curve, respectively. Then, using the ${\it UBVRI}$ time-series photometry, we unambiguously identify the dominant frequency $\nu _1$ as the radial mode, whereas in the case of frequencies $\nu _2$ and $\nu _3$ the most probable mode degrees are $\ell =0$ or $\ell =2$. However, only the frequency $\nu _2$ can be associated with a radial mode, and only if higher order effects of rotation are taken into account. Including the rotational mode coupling, we constructed complex seismic models of V2367 Cyg, which fit $\nu _1$ and $\nu _2$ as radial modes, and reproduce the amplitude of bolometric flux variations (the parameter f) for the dominant mode. The empirical values of f are derived from the ${\it UBVRI}$ amplitudes and phases. We rely on the Bayesian analysis based on Monte Carlo simulations to derive constraints on evolutionary stage, mass, rotation, overshooting from the convective core, and efficiency of convective transport in the envelope. Our seismic analysis clearly indicates that V2367 Cyg is in a post-main sequence phase of evolution. This is the first extensive seismic modelling that takes into account the effect of rotational coupling between pulsation modes.

Open-ended versus bounded evolution: Mineral evolution as a case study.

To what extent are naturally evolving systems limited in their potential diversity (i.e. "bounded") versus unrestricted ("open-ended")? Minerals provide a quantitative model evolving system, with well-documented increases in mineral diversity through multiple stages of planetary evolution over billions of years. A recent framework that unifies behaviors of both biotic and abiotic evolving systems posits that all such systems are characterized by combinatorial richness subject to selection. In the case of minerals, combinatorial richness derives from the possible combinations of chemical elements coupled with permutations of their formulas' coefficients. Observed mineral species, which are selected for persistence through deep time, represent a miniscule fraction of all possible element configurations. Furthermore, this model predicts that as planetary systems evolve, stable minerals become an ever-smaller fraction of the "possibility space." A postulate is that "functional information," defined as the negative log2 of that fraction, must increase as a system evolves. We have tested this hypothesis for minerals by estimating the fraction of all possible chemical formulas observed from one stage of mineral evolution to the next, based on numbers of different essential elements and the maximum chemical formula complexity at each of nine chronological stages of mineral evolution. We find a monotonic increase in mineral functional information through these nine stages-a result consistent with the hypothesis. Furthermore, analysis of the chemical formulas of minerals demonstrates that the modern Earth may be approaching the maximum limit of functional information for natural mineral systems-a result demonstrating that mineral evolution is not open-ended.

Research on the evolution of cross-platform online public opinion for public health emergencies considering stakeholders.

To explore the different processes of the themes and emotional evolution of various stakeholders in the network public opinion of sudden public health emergencies at different stages of the public opinion evolution lifecycle. This paper proposes a cross-platform analysis method for online public opinion during the public health emergencies based on stakeholders. Firstly, data from multiple platforms are collected and integrated. Secondly, stakeholders are categorized and the stages of public opinion evolution are determined based on stakeholder theory and lifecycle theory. Finally, the Latent Dirichlet Allocation (LDA)+Word2vec model and Convolutional Neural Network (CNN) model are used to analyze the themes and emotional evolution of stakeholders during different stages of public opinion evolution. There are differences in the evolution patterns of different types of stakeholders. The evolution process of stakeholders' focus points exhibits a two-stage transition from concentration to divergence. The focus points of stakeholders are closely associated with their respective social domains. The emotions of the public undergo a three-stage process of positive-negative-positive change. This study can provide a reference for the government to have a more comprehensive understanding of the development trend of public opinion and reduce the negative impact of public opinion.

On the Origin of soft ticks (Parasitiformes, Ixodoidea, Argasidae)

The origin of the common evolutionary branch of soft and hard ticks is dated to the later Permian, approximately coinciding with the Permian extinction, and divergence of the common branch of Ixodoidea into ancestral forms of Argasidae and Ixodidae occurred in the Triassic. Ancestors of the common branch of Ixodoidea (Ixodidae, Argasidae, Nuttalliellidae) were not bloodsucking arthropods and were closely related to modern representatives of Holothyridae. Bloodsucking and, later, temporary ectoparasitism had developed only after divergence of the main branches (Ixodidae, Argasidae and Nuttalliellidae), independently in each group. At early stages of the soft tick evolution, bloodsucking was a short-time process, long-time feeding had developed later in larvae and promoted dispersal of ticks. Maintenance of the short-time feeding can be explained by adaptation to dwelling in bird nests or in shelters visited by birds, and later, also in mammal burrows. Displacements of gnathosomе to the ventral side of idiosome hampered combing of a parasite from the host during short-time bloodsucking. Short-time feeding resulted in maintenance and development of coxal glands as the main organ for removal of superfluous liquid during bloodsucking. Adaptation to shelter habitats (nests, burrows, rock crevices, under dead tree cork, etc.) promoted development of polyphagia and adaptations for long-term starvation.

SNA in National Statistics: Origins and Stages of Evolution

The article considers the history of the System of National Accounts (SNA) and the main stages of its evolution in domestic statistics. A transition to the SNA was made from the Balance of the National Economy (BNE) – a system of macroeconomic indicators used in the USSR. It is noted that the experience of compiling BNE tables helped soviet statisticians master the SNA relatively fast.The authors give special attention to 2008 SNA innovations and issues that Rosstat deals with in modern conditions. They, in particular, address evaluating the performance of the unobserved economy, treatment of holding gains, and computation of output of financial intermediaries. The authors comment on problems of treatment of outlays on research and development, military equipment in context with implementing the 2008 SNA, and issues with estimating GDP at constant prices. It is indicated that Rosstat is currently developing all the main accounts provided for by the 2008 SNA international standard. These data are used to guide economic and social government policy.In conclusion, it is noted that Rosstat today is preparing to implement the provisions of the updated version of the 2008 SNA international standard, which is to be adopted at the UN Statistical Commission’s spring session of 2025. It will be a new stage in the evolution of national accounting in Russia.

Is a more physical representation of aerosol chemistry needed for fog forecasting?

AbstractWith the changing climate, the study of fog formation is essential due to the impact of the complexity of natural and anthropogenic aerosols. The evolution of the droplet size distribution in the presence of different aerosol species remains poorly understood. To make progress towards reducing the uncertainty of fog forecasts, the Eulerian–Lagrangian particle‐based small‐scale model for the diffusional growth of droplets is used to better understand the droplet activation and growth. The small‐scale model simulations are performed using observed data from the Winter Fog Experiment study over Indira Gandhi International Airport, New Delhi. The microphysical properties, such as droplet number concentrations (Nd) and liquid water content (LWC), important for fog simulation, are evaluated to gain more insights. The small‐scale simulations have shown the droplet microphysical properties at different evolutionary stages. The Nd and effective radius change with variations in LWC for different aerosol chemistries (i.e., organics, mix, and inorganic). The calculated visibility at small scale is also shown with the variation of Nd and LWC. This study compared visibility from an existing parametrization with parcel–direct numerical simulation calculation. The hygroscopicity , which is highly related to the activation of aerosols to condensation nuclei, is taken into account to demonstrate the contribution of aerosol chemistry to fog droplet formation. The results highlight that hygroscopicity is essential in the numerical model for fog and visibility prediction as the microphysical properties of fog are regulated by aerosol species.

Middle Silurian–Middle Devonian Magmatic Rocks in the Eastern Segment of the Northern Margin of the North China Craton: Implications for Regional Tectonics

This paper presents a detailed study including LA-ICP-MS zircon U-Pb dating, geochemical, zircon Hf isotope, and whole rock Sr-Nd isotope analysis of magmatic rocks from the Yitong County, Jilin Province, NE China. These data are used to better constrain the Middle Silurian–Middle Devonian tectonic evolution in the eastern segment of the northern margin of the North China Craton (NCC). Zircon U-Pb dating results show that the Ximangzhang tonalite formed in the Late Silurian (425 ± 6 Ma); the basalt, andesite, and metamorphic olivine-bearing basalt in the Fangniugou volcanic rocks formed in the Middle Silurian (428 ± 6.6 Ma) and Middle Devonian (388.4 ± 3.9 Ma, and 384.1 ± 4.9 Ma). The Late Silurian tonalites are characterized by high SiO2 and Na2O and low K2O, MgO, FeOT, and TiO2, with an A/CNK ratio of 0.91–1.00, characteristic of calc-alkaline I-type granite. They are enriched in Rb, Ba, Th, U, and K, and depleted in Nb, Sr, P, and Ti, with positive εNd(t) (+0.35) and εHf(t) (+0.44 to +6.31) values, suggesting that they mainly originated from the partial melting of Meso–Neoproterozoic accretionary lower crustal material (basalt). The Middle Silurian basalts are characterized by low SiO2, P2O5, TiO2, and Na2O and high Al2O3, FeOT, and K2O, enriched in Rb, Ba, Th, U, and K and depleted in Nb, Ta, Sr, P, and Ti, indicative of shoshonitic basalt. The Late Silurian tonalites have positive εNd(t) (+4.91 to +6.18) values and primarily originated from depleted mantle magmas metasomatized by subduction fluids, supplemented by a small amount of subducted sediments and crustal materials. The Middle Devonian volcanic rocks exhibit low SiO2, TiO2, and Na2O and high K2O, and MgO, enriched in Rb, K, and LREEs and depleted in Nb, Ta, Sr, and HREEs, characteristic of shoshonitic volcanic rocks. Their εNd(t) (+2.11 to +3.77) and εHf(t) (+5.90 to +11.73) values are positive. These characteristics indicate that the Middle Devonian volcanic rocks primarily originated from depleted mantle magmas metasomatized by subduction fluids, with the addition of crustal materials or subducted sediments during their formation. Based on regional geological data, it is believed that the study area underwent the following evolutionary stages during the Silurian–Devonian period: (1) active continental margin stage of southward subduction of the Paleo–Asian Ocean (PAO) (443–419 Ma); (2) arc-continent collision stage (419–405 Ma); (3) post-collision extension stage (404–375 Ma); (4) active continental margin stage, with the PAO plate subducting southward once again (375–360 Ma).

Magmatic sulfide oxidation drives crustal PGE mobilization: Implications for hydrothermal PGE mineralization

Platinum-group elements (PGEs) have a strong affinity for sulfur and tend to accumulate in the deep continental crust, either concentrated within magmatic Cu-Ni-PGE deposits or dispersed throughout disseminated sulfides. However, PGE enrichment in shallow magmatic-hydrothermal systems implies an obscure link to deep sulfide destabilization, which releases PGEs into ore-forming fluids. To bridge this gap, our study investigates the PGE composition of magmatic sulfides with oxidative textures in dacitic rocks from the southwestern Okinawa Trough. We identified three groups of magmatic sulfides, primarily precipitated as Cu-poor monosulfide solid solution (MSS), which formed at distinct stages of magma evolution from deep to shallow crustal levels. Group A sulfides manifest as small-sized inclusions (<30 μm) within most high-Mg olivines, whereas Group B and C sulfides are larger (50–500 μm) and occur within cognate xenoliths of mafic cumulate rocks and the groundmass of host dacites. Group B and C sulfides exhibit distinct oxidative textures and newly-formed mineral assemblages, including magnetite, hematite, goethite, and magnetite ± pyrite, alongside hydrothermal silicate minerals, respectively. We attribute the oxidation process to the infiltration of orthomagmatic fluids exsolved from mafic magma that had underplated the sulfide-bearing felsic magma reservoir, which was nearly solidified. By comparing the chemical compositions between pristine sulfides and their oxidative remnants, we observed extensive mobilization of Pd, Pt, Cu, Ag, Ni, and Co from the altered sulfides of Group B, while Au enrichment occurred as nanoparticles under high oxidation states. In contrast, Au was extracted along with other mobile metals from the altered sulfides of Group C, with Pt remaining in place under more reduced conditions. These distinct scenarios may lead to the formation of PGE-rich and Au-rich fluids, respectively. The formation of deep crustal MSS and subsequent hydrothermal oxidation under varying redox conditions thus provides a viable mechanism for trans-crustal PGE mobilization and inter-element fractionation, typical of PGE-rich magmatic-hydrothermal deposits.

Host galaxy of low-luminosity compact sources

The term `active galactic nuclei' (AGN) is applied to a huge variety of objects, classified on the basis of their properties at different wavelengths. Peaked sources (PSs) represent a class of AGN at the first stage of evolution, characterised by a peaked radio spectrum. Among these radio sources, low-luminosity compact (LLC) sources can be identified as PSs accreting with a high Eddington rate, harbouring low-power jets, and hosting low-mass black holes. These properties are also shared by narrow-line Seyfert 1 galaxies (NLS1s). In 2016, LLCs were hypothesised to be the parent population of NLS1s with a flat radio spectrum (F-NLS1s), suggesting that the former may be the same objects as the latter but, instead, seen at a higher inclination. Based on radio luminosity functions and optical spectra analysis, ten LLCs were identified as valid F-NLS1s candidates. To account for the missing piece to the puzzle and verifying whether these LLCs could be hosted in late-type galaxies as NLS1s, we performed a photometric decomposition of their Pan-STARRS1 images in all five filters. We used the 2D fitting algorithm GALFIT for the single-band analysis and its extension GALFITM for the multi-band analysis. Considering that the morphological type and the structural parameters of the host may be dependent on the wavelength, we found six out of ten LLCs hosted in late-type galaxies, probably with pseudo-bulges, along with three point-like sources and one object of an uncertain classification. Although this study is based on a small sample, it represents the first morphological analysis of LLC host galaxies. These results confirm the trend observed in NLS1s, indicating late-type and disc-like host galaxies for LLCs and supporting the validity of the parent population scenario.

Mediapolitical Discourse: Concepts and Framework

Introduction. The article presents the results of the review of scientific works on discourse theory, reflecting the stages of evolution of media-political discourse in Russian linguistics. The aim of the article is to summarize, systematize and analyze approaches to the study of media-political discourse and concepts of its comprehension. Such concepts as media discourse, media text, media linguistics, and political discourse are considered.Methodology and sources. The article is prepared in the context of the cognitive-discursive paradigm, functional approach to discourse analysis, and media linguistics. In accordance with the postulates of critical discourse analysis, media-political discourse is considered as a constitutive of social practice. The main research method is an analytical scientific review of works on discourse theory.Results and discussion. In the course of the review of works on media and political discourse the main approaches to the understanding and research of media-political discourse are highlighted. The boundaries of this type of discourse as one of the areas of modern discourse theory are outlined. The concepts of scientific cognition that conditioned the formation of media-political discourse are identified. A review of works on related types of discourse at the previous stages of scientific thought is given. Internet discourse is viewed as an alternative source of political information. The article emphasizes the elements of language of enmity and the binary opposition “us/them” in the media-political discourse.Conclusion. The paper reveals a tendency to merge media discourse and political discourse within the framework of media-political discourse in modern linguistics. Among the key approaches to the study of media-political discourse the following approaches are identified: cratological, structural-communicative and media-technological ones; when analyzing the blogosphere it is advisable to refer to critical discourse analysis, structuralfunctional and comparative approaches. The most promising areas of the research include the identification of the essential characteristics of media-political discourse, and the development of genre stratification of this type of discourse.

Rock-like material under large diameter SHPB dynamic splitting tension: meso-damage mechanical behavior and stress wave propagation model

The mechanical behavior of splitting tensile damage and the law of stress wave propagation of rock-like materials (RLM) are of great significance to further reveal the dynamic disaster mechanism of the deep rock mass. The meso-damage mechanical behavior and stress wave propagation characteristics of RLM disks under impact splitting were studied by using a large diameter split Hopkinson pressure bar (SHPB). In terms of dynamic damage, the splitting tensile stress-compression strain curves of RLM disks obviously showed three stages of mechanical behavior evolution: initial elastic-plastic deformation, pre-peak plastic damage, and post-peak brittle fracture failure. The macro-damage of RLM disks increased with the increase of strain rate. The meso-tensile fracture was the result of both the initial meso-damage and the impact splitting meso-damage. The dynamic splitting damage variable defined based on the damage fracture energy can accurately describe the damage evolution characteristics of impact splitting on RLM disks. In the aspect of stress wave propagation, the peak value of transmission stress showed an advanced effect with the increase of incident stress wave. In the early stage (0–50 μs), the transmission stress wave ratio (σT/σI) increased with the increase of strain rate, while in the later stage (82–200 μs), the transmission stress wave ratio (σT/σI) decreased with the increase of strain rate. The stress wave propagation law in the process of impact splitting on RLM disks was clearly revealed based on the stress wave propagation model established by the one-dimensional elastic stress wave theory. Finally, the dynamic mechanical mechanism of splitting damage and fracture of RLM disks under different strain rates was discussed deeply.

He-enriched starevol models for globular cluster multiple populations. Self-consistent isochrones from ZAMS to the TP-AGB phase

A common property of globular clusters (GCs) is to host multiple populations characterized by peculiar chemical abundances. Recent photometric studies suggest that the He content could vary between the populations of a GC by up to Delta He sim 0.13, in mass fraction. The initial He content impacts the evolution of low-mass stars by ultimately modifying their lifetimes, luminosity, temperatures, and, more generally, the morphology of post-red giant branch (RGB) evolutionary tracks in the Hertzsprung-Russell diagram. We present new physically accurate isochrones with different initial He enrichments and metallicities, with a focus on the methods implemented to deal with the post-RGB phases. The isochrones are based on tracks computed with the stellar evolution code starevol for different metallicities (Z = 0.0002, 0.0009, 0.002, and 0.008) and with a different He enrichment (from 0.25 to 0.6 in mass fraction). We describe the effect of He enrichment on the morphology of the isochrones, and we tested these by comparing the predicted number counts of horizontal branch and asymptotic giant branch stars with those of selected GCs. Comparing the number ratios, we find that our new theoretical ones agree with the observed values within $1 in most cases. The work presented here sets the ground for future studies on stellar populations in GCs, in which the abundances of light elements in He-enhanced models will rely on different assumptions for the causes of this enrichment. The developed methodology permits the computation of isochrones from new stellar tracks with noncanonical stellar processes. The checked number counts ensure that, at least in this reference set, the contribution of the luminous late stages of stellar evolution to the integrated light of a GC is represented adequately.

Runaway BN supergiant star HD 93840: Progenitor of an imminent core-collapse supernova above the Galactic plane

We present a quantitative spectral analysis of the extreme nitrogen-enhanced supergiant HD 93840 (BN1\,Ib) at an intermediate galactic latitude. Based on an optical high-resolution spectrum and complementary ultraviolet and infrared (spectro-)photometry, in addition to Gaia data, we carried out a full characterisation of the star's properties. We used both hydrostatic and unified (photosphere+wind) model atmospheres that account for deviations from local thermodynamic equilibrium. A highly unusual surface CNO-mixing signature and a marked stellar overluminosity compared to the mass imply a binary channel for the star's past evolution. The kinematics shows that it has reached its current position above the Galactic plane as a runaway star, likely ejected by the supernova explosion of its former companion star. Its current bulk composition, with a notably increased mean molecular weight due to core He- and progressed shell H-burning, suggests an advanced evolutionary stage. It is poised to yield a rare core-collapse supernova of a blue supergiant about ten OB star population scale heights above the Galactic disk relatively soon, contributing to the metal enrichment of the circumgalactic medium.