The Three Hundred Project: Dynamical state of galaxy clusters and morphology from multi-wavelength synthetic maps

We study the connection between morphology and dynamical state of the simulated galaxy clusters in z ∈ [0, 1.031] from The Three Hundred Project. We quantify cluster dynamical state using a combination of dynamical indicators from theoretical measures and compare this combined parameter, χ, with the results from morphological classifications. The dynamical state of the cluster sample shows a continuous distribution from dynamically relaxed, more abundant at lower redshift, to hybrid and disturbed. The dynamical state presents a clear dependence on the radius, with internal regions more relaxed than outskirts. The morphology from multi-wavelength mock observation of clusters in X-ray, optical, and Sunyaev-Zel’dovich (SZ) effect images, is quantified by M – a combination of six parameters for X-ray and SZ maps and the offsets between the optical position of the Brightest Central Galaxy (BCG) and the X-ray/SZ centroids. All the morphological parameters are highly correlated with each other, while they show a moderately strong correlation with the dynamical χ parameter. The X-ray or SZ peaks are less affected by the dynamical state than centroids, which results in reliable tracers of the cluster density peak. The principal source of contamination in the relaxed cluster fraction, inferred from morphological parameters, is due to dynamically hybrid clusters. Compared to individual parameters, which consider only one aspect of cluster property (e.g. only clumping or asymmetry), the combined morphological and dynamical parameters (M and χ) collect more information and provide a single and more accurate estimation of the cluster dynamical state.

An OD Flow Clustering Method Based on Vector Constraints: A Case Study for Beijing Taxi Origin-Destination Data

Origin-destination (OD) flow pattern mining is an important research method of urban dynamics, in which OD flow clustering analysis discovers the activity patterns of urban residents and mine the coupling relationship of urban subspace and dynamic causes. The existing flow clustering methods are limited by the spatial constraints of OD points, rely on the spatial similarity of geographical points, and lack in-depth analysis of high-dimensional flow characteristics, and therefore it is difficult to find irregular flow clusters. In this paper, we propose an OD flow clustering method based on vector constraints (ODFCVC), which defines OD flow event point and OD flow vector to express the spatial location relationship and geometric flow behavior characteristics of OD flow. First, the OD flow vector coordinate system is normalized by the Euclidean distance-based OD flow event point spatial clustering, and then the OD flow clusters with similar flow patterns are mined using adjusted cosine similarity-based OD flow vector feature clustering. The transformation of OD data from point set space to vector space is realized by constraining the vector coordinate system and vector similarity through two-step clustering, which simplifies the calculation of high-dimensional similarity of OD flow and helps mining representative OD flow clusters in flow space. Due to the OD flow cluster property, the k-means algorithm is selected as the basic clustering logic in the two-step clustering method, and a sum of squared error perceptually important points algorithm considering silhouette coefficients (SSEPIP) is adopted to automatically extract the optimal cluster number without defining any parameters. Tested by origin-destination flow data in Beijing, China, new traffic flow communities based on traffic hubs are obtained by using the ODFCVC method, and irregular traffic flow clusters (including cluster mode, divergence mode, and convergence mode) with representative travel trends are found.

A molecular dynamics study of nanoscale titanium nitrides formation in ferrite

Molecular dynamics simulation was adopted to investigate the nanoscale titanium nitride formation at the early formation stage in high-strength low-alloy steel. During the cluster formation process, the nitride clusters were formed through the atom aggregation. The atomic interactions of titanium and nitride atoms were revealed and the cluster property was discussed. The nanoscale titanium nitride clusters own a wide composition, and the cluster formation mechanism was concluded.

The XXL Survey

Context. Scaling relations between cluster properties embody the formation and evolution of cosmic structure. Intrinsic scatters and correlations between X-ray properties are determined from merger history, baryonic processes, and dynamical state. Aims. We look for an unbiased measurement of the scatter covariance matrix among the three main X-ray observable quantities attainable in large X-ray surveys: temperature, luminosity, and gas mass. This also gives us the cluster property with the lowest conditional intrinsic scatter at fixed mass. Methods. Intrinsic scatters and correlations can be measured under the assumption that the observable properties of the intra-cluster medium hosted in clusters are log-normally distributed around power-law scaling relations. The proposed method is self-consistent, based on minimal assumptions, and requires neither external calibration by weak lensing, or dynamical or hydrostatic masses, nor the knowledge of the mass completeness. Results. We analysed the 100 brightest clusters detected in the XXL Survey and their X-ray properties measured within a fixed radius of 300 kpc. The gas mass is the less scattered proxy (∼8%). The temperature (∼20%) is intrinsically less scattered than the luminosity (∼30%), but it is measured with a larger observational uncertainty. We found some evidence that gas mass, temperature, and luminosity are positively correlated. Time evolutions are in agreement with the self-similar scenario, but the luminosity–temperature and the gas mass–temperature relations are steeper. Conclusion. Positive correlations between X-ray properties can be determined by the dynamical state and the merger history of the halos. The slopes of the scaling relations are affected by radiative processes.

The Incidents of Legal Personhood

The chapter presents a new theory of legal personhood. It argues that legal personhood is a cluster property, and best understood in terms of disseverable but interconnected incidents. It sets out by distinguishing passive and active incidents, and then enumerates and presents both types of incidents. While doing so, the chapter highlights the benefits of an incident-based approach to legal personhood. After presenting the incidents, the notion of a ‘subject of law’ is offered as an alternative way of analysing legal personhood. The chapter concludes by addressing some of the connections between personhood and legal personhood.

A Theory of Legal Personhood

Legal personhood is a foundational concept of Western legal thought. It has recently become highly topical, underpinning contemporary debates over the legal status of animals, corporations, foetuses, natural objects, and artificial intelligences. The notion is furthermore crucial in explaining the historical legal statuses of women and slaves. Rather than addressing who or what should be a legal person, this book examines the concept itself. The book consists of an Introduction and three parts. The Introduction presents the Western doctrine of legal personhood, the relevant terms and concepts, and the methodology employed in the book. Part I shows, first, how legal personhood came to be understood synonymously with the holding of legal rights and/or duties. It then subjects this understanding of legal personhood to a rigorous scrutiny, exposing numerous problems afflicting the view. Part II provides a completely new, general theory of legal personhood, arguing that legal personhood is best understood as a cluster property, consisting of distinct incidents. The final part applies the new theory to explain and structure the numerous debates surrounding legal personhood, explaining what is at stake in the animal legal personhood trials taking place in the US and elsewhere.