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In this study, a novel approach is presented for simulating transient heat conduction in functionally graded materials (FGM) with varying material properties only in the z direction. The proposed collocation method employs a meshless localized space–time radial basis function (LSTRBF), which yields a linear sparse matrix system, offering advantages over the global method in terms of scalability and suitability for multidimensional problems. Additionally, a novel shape parameter strategy, known as variable leave-one-out cross-validation (LOOCV), is introduced to enhance accuracy while overcoming conventional LOOCV limitations. Four benchmark numerical examples are utilized to demonstrate the simplicity, efficiency, accuracy, and stability of the method. Overall, the proposed LSTRBF method presents a promising alternative for efficiently and accurately simulating transient heat conduction in FGMs. [ABSTRACT FROM AUTHOR]

Female domestic workers (FDWs) experience space–time constraints and mobility challenges corresponding to their demanding daily work responsibilities. Studies have shown that FDWs' mobility and activities are primarily dictated by their employers through work tasks. It is unclear, though, how FDWs' activity and mobility patterns outside their employers' homes are shaped by individual and contextual factors, including government policies that mandate that FDWs be granted a rest day. Using an activity space approach combined with multilevel modeling, I evaluated mobility and activity patterns on work and rest days for a sample of Indonesian FDWs in Hong Kong. Data were collected using innovative online activity diaries and were triangulated with qualitative data from WhatsApp follow-up conversations. This research uncovers that FDWs' activity patterns differ significantly between work and rest days. FDWs rarely go outside on workdays except to perform work-related tasks. On the rest day, FDWs' activity spaces are much more expansive as they conduct social and personal activities that are essential for maintaining their well-being. By comparing work and rest days, this research deepens our understanding of geographical, social, and temporal aspects of FDWs' space–time constraints and (im)mobility experiences that encompass and go beyond employer-assigned tasks. Furthermore, the findings demonstrate the benefits of rest day policies for enhancing the visibility of marginalized women in public spaces, particularly in the context of FDWs' restrictive space–time constraints. [ABSTRACT FROM AUTHOR]

We investigate the geometry of space-time prisms and their associated potential path areas (for movement that takes place in the plane) in the setting where the prism anchors have a spatial uncertainty area attached to them. Our main result is a characterisation of such space-time prisms and their potential path areas in terms of a generalised distance function between closed subsets of the ambient space. Since the case where this spatial anchor uncertainty takes the form of a closed disk has already been addressed by Kuijpers and Othman (2017), we focus on the more realistic case where the uncertainty areas are ellipses and we apply our general characterisation to this example to obtain explicit descriptions of the uncertain prisms and their potential path areas. [ABSTRACT FROM AUTHOR]

Research examining migrant homemaking is multi-disciplinary and well-developed, providing evidence that 'home' exists in multiple places. However, only a small component of this work examines the role of the senses. This paper draws on research conducted between 2015 and 2019 in Glasgow, a city in Scotland, UK, with migrant, refugee and asylum-seeking women that used photo elicitation interviews, to bridge the gap between scholarship on migrant homemaking and the senses. The paper empirically demonstrates how the senses allow migrants to cultivate the embodied experience of physically being elsewhere by drawing on sensory memories, practices, and material cultures, specifically engaging taste and smell. The paper analyses the experience of four participants who described this sensation, and addresses the impact of the security of migrant status and financial resources in sensory homemaking. The concluding discussion proposes the concept of 'sensory space-time compression' as a novel way of understanding the sensory experiences of home in the context of migration. [ABSTRACT FROM AUTHOR]

The paper argues for the renewed relevance of time geography in tourism in light of the use of mobile technologies and ubiquitous connectivity. The paper proposes the concept of phygitality to understand how digital technologies are used in physical space, and how the interaction between the physical and the digital reconfigures tourists' projects, paths, bundles, and constraints. The theoretical contribution builds on fifteen semi-structured interviews. The analysis shows that capability, coupling, and authority constraints are altered and mediated by digital devices. In the phygital time-space, tourists orient themselves in physical spaces, influenced by digital information; they create phygital paths and move between stations that result from the overlaying of digital information onto the physical space. Tourists' goal-oriented mobility results in phygital projects, where logics of efficiency and optimization reduce the liminality of the tourist experience. Tourists' bundles are created within and outside the physical vacation prism through digital communication. [ABSTRACT FROM AUTHOR]

In this paper, we propose a space-time Galerkin spectral method for the time fractional Fokker–Planck equation. This approach is based on combining temporal Müntz Jacobi polynomials spectral method with spatial Legendre polynomials spectral method. Based on the well-posedness and regularity for the re-scaled problem of a linear model problem which reflects the main difficulty for solving the equivalent equation (i.e. the time fractional convection-diffusion equation): the singularity of the solution in time, we explain in detail why we use the Müntz polynomials to approximate in time. The well-posedness and stability of the discrete scheme as well as its continuous problem are established. Moreover, the error estimation of the space-time approach is derived. We find that the proposed method can attain spectral accuracy regardless of whether the solution of the original equation is smooth or non-smooth. Numerical experiments substantiate the theoretical results. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has had a profound impact worldwide and continues to spread due to various mutations of the virus. Many governmental and nonprofit agencies at different levels have quickly developed COVID-19 dashboards to disseminate information on the pandemic to the public. However, most of these systems have mainly distributed "plain" information (e.g. cases, death counts, vaccination), and rarely provided insights that can be gained from spatiotemporal analyses, such as the detection of emerging clusters. The results from these analyses hold tremendous potential for health policymakers as they try to identify ways to slow down transmission. We present a web-based geographic framework to detect and visualize space-time clusters of COVID-19. Our tightly coupled framework integrates the prospective space-time scan statistics and local indicators of spatial association (LISA) with novel 2D and 3D interactive visuals in a cyber environment (). We illustrate the applicability of our approach using COVID-19 data for the continental US. Our framework is portable to other regions that may experience infectious diseases but is also flexible to handle data of different spatial and temporal granularities. This paper fits within an effort to integrate space-time analytics for the monitoring of infectious diseases in web environment, ultimately improving health surveillance systems. [ABSTRACT FROM AUTHOR]

In this paper, we study the extreme value behavior of the space-time process given by X i (t) = ∑ j ≥ 1 Ψ ij (t) Z i − j (t) , t ∈ [ 0 , 1 ] , i ∈ Z. We assume that { Z i (t) } t ∈ [ 0 , 1 ] , i ∈ Z is a sequence of i.i.d random fields on [ 0 , 1 ] with values in the Skorokhod space D [ 0 , 1 ] of càdlàg functions (i.e., right-continuous functions with left limits) D [ 0 , 1 ] equipped with the J1 topology. The coefficients { Ψ ij (t) } t ∈ [ 0 , 1 ] , i ∈ Z are processes with continuous sample paths. Our first aim is to establish a limit theory for point processes based on X(t). Secondly, using point processes, we study the limiting distribution of the normalized maximum process { a n − 1 max 1 ≤ i ≤ n X i (t) } t ∈ [ 0 , 1 ] . The result obtained in the second step can be viewed as extension of Balan who postponed the study of the behavior of maxima. It can also be considered as a generalization of Davis and Mikosch from deterministic real coefficients to random coefficients (Ψ ij) i ≥ 1 . [ABSTRACT FROM AUTHOR]

Recent years in time geography have witnessed a flourishment of space–time prism (STP) modeling extensions for enhancing realism. However, there is little research on the incorporation of monetary budget in STP models to capture personal potential mobility space more realistically. This study considers both time and monetary budget constraints in STP modeling in a multimodal supernetwork integrating mobility-as-a-service and trip chains. We develop an efficient two-stage bi-criterion bidirectional search method to identify Pareto path sets to construct the resulting STP for conducting a flexible activity between two anchor nodes. To demonstrate the effectiveness of the proposed model and solution method, a case study with varying scenarios is conducted to evaluate the impacts of monetary budget on space–time accessibility and equality. The findings show that the ignorance of monetary budget overestimates accessibility and that MaaS, if not well designed, may not improve equality in accessibility as intended. [ABSTRACT FROM AUTHOR]

The article focuses on "The Great Historical Clock of America," an immense clock from 1890 exhibited in the Smithsonian's National Museum of American History. Topics include the clock's dimensions, intricate decorations depicting scenes from U.S. history, and its significance as an uncommon object with a life history that reveals connections between people and things. The article explores the concept of object biography, tracing the clock's journey through time and space.

The doctrine of transubstantiation (as understood by Aquinas and much subsequent Roman Catholic theology) involves the counter-intuitive claim that accidents can come to exist independently of any substance. In particular, the spatial dimensions of bread and wine can come to exist independently. I point out that a key idea that motivated this claim was an aspect of mediaeval philosophy of nature: namely, relationism about space. I argue that if relationism is dropped in favour of substantivalism, then room is made for a model of transubstantiation which needn't involve an implausible commitment to independently existing accidents. [ABSTRACT FROM AUTHOR]

In this paper, a modified two-grid algorithm based on block-centred finite difference method is developed for the fourth-order nonlinear extended Fisher–Kolmogorov equation. To further improve the computational efficiency, an effective second-order accurate backward difference formula is considered. The modified two-grid method based on Newton iteration is constructed to linearize the nonlinear system. The method solves a miniature nonlinear system on a coarse grid accompanying a larger time step to get the numerical solution, then computes a linear system constructed by the previous result with the Taylor expansion on a fine grid accompanying a smaller time step to get the correct numerical solution. Theoretical analysis shows that the modified two-grid algorithm can achieve second-order convergence accuracy both in time and space domain. Several numerical experiments are provided to verify the theoretical result and the high efficiency of this approach. The practical problem illustrates the actual applicable value of the algorithm. [ABSTRACT FROM AUTHOR]

We give an elementary new argument for global existence and exponential decay of solutions of quasilinear wave equations on Schwarzschild–de Sitter black hole backgrounds, for appropriately small initial data. The core of the argument is entirely local, based on time translation invariant energy estimates in spacetime slabs of fixed time length. Global existence then follows simply by iterating this local result in consecutive spacetime slabs. We infer that an appropriate future energy flux decays exponentially with respect to the energy flux of the initial data. [ABSTRACT FROM AUTHOR]

In recent years, slow travel modes (walking, cycling) have gained much interest in the context of urban air quality management. This article presents the findings from a novel air quality measurement experiment in the Netherlands, by regarding cyclists as carriers and transmitters of real-world information on fine-grained air quality conditions. Using individual sensors on bicycles—connected to a GPS positioning system—online local pollution information originating from cyclists' detailed spatial mobility patterns is obtained. Such air quality surface maps and cyclists' mobility maps are then used to identify whether there are significant differences between the actual route choice and the cyclists' shortest route choice, so as to identify the implications of poor air quality conditions for their mobility choices. Thus, the article seeks to present both a detailed pollution surface map and the complex space-time mobility patterns of cyclists in a region, on the basis of online quantitative data—at any point in time and space—from bicycle users in a given locality. In addition, the article estimates their response—in terms of route choice—to detailed air-quality information through the use of a novel geoscience-inspired analysis of space-time "big data." The empirical test of our quantitative modeling approach was carried out for the Greater Utrecht area in the Netherlands. Our findings confirm that spatial concentration of air pollutants have great consequences for bike users' route choice patterns, especially in the case of non-commuting trips. We also find that cyclists make longer trips on weekends and in the evenings, especially towards parks and natural amenities. [ABSTRACT FROM AUTHOR]

Waiting is spatial, gendered, and hidden. Drawing on ethnographic field work with cleaners in railway facilities of Hyderabad, India, and building on infrastructure and mobilities studies, I theorize the space-time of waiting. I propose waiting as a multivalent lens through which to view power, space, and labor relations. Second, I argue that waiting is a method offering possibilities for understanding the Sisyphean task of cleaning and uneven, precarious, and diverse urban worlds. Waiting is integral to maintenance work, and pivotal to the production of "clean" infrastructures, yet it remains invisible. Third, I posit waiting as praxis: a mode of field work grappling with place-based realities. Waiting is learning the station. My article considers the social and economic (im)mobilities that underpin the waiting of cleaning workers. I further posit queues as microinfrastructures of waiting. Finally, I argue that waiting, when employed as a method, and as praxis, reveals the uneven urban worlds, relational spaces, and the everydayness of capitalism. [ABSTRACT FROM AUTHOR]

Sharp Besov regularities in time and space variables are investigated for (u (t , x) , t ∈ [ 0 , T ] , x ∈ R) , the mild solution to the stochastic heat equation driven by space–time white noise. Existence, Hölder continuity, and Besov regularity of local times are established for u (t , x) viewed either as a process in the space variable or time variable. Hausdorff dimensions of their corresponding level sets are also obtained. [ABSTRACT FROM AUTHOR]

For spatially dependent functional data, a generalized Karhunen-Loève expansion is commonly used to decompose data into an additive form of temporal components and spatially correlated coefficients. This structure provides a convenient model to investigate the space-time interactions, but may not hold for complex spatio-temporal processes. In this work, we introduce the concept of weak separability, and propose a formal test to examine its validity for non-replicated spatially stationary functional field. The asymptotic distribution of the test statistic that adapts to potentially diverging ranks is derived by constructing lag covariance estimation, which is easy to compute for practical implementation. We demonstrate the efficacy of the proposed test via simulations and illustrate its usefulness in two real examples: China PM 2.5 data and Harvard Forest data. for this article are available online. [ABSTRACT FROM AUTHOR]

In this paper, we prove some blow-up results for the semilinear wave equation in generalized Einstein-de Sitter spacetime by using an iteration argument, and we derive upper bound estimates for the lifespan. In particular, we will focus on the critical cases which require the employment of a slicing procedure in the iterative mechanism. Furthermore, in order to deal with the main critical case, we will introduce a non-autonomous and parameter-dependent Cauchy problem for a linear ODE of second-order, whose explicit solution will be determined by applying the theory of special functions. [ABSTRACT FROM AUTHOR]

Clustering the trajectories of vehicles moving on road networks is a key data mining technique for understanding human mobility patterns, as well as their interactions with urban environments. The development of efficient and scalable trajectory clustering algorithms, however, still faces challenges because of the computational costs when measuring similarities among a large number of network-constrained trajectories. To address this problem, a novel trajectory clustering framework based on the well-developed Density-Based Spatial Clustering of Applications with Noise (DBSCAN) approach is proposed. This proposed framework accurately quantifies similarities using a trajectory representation of continuous polylines in the space and time dimensions, and does not require trajectory discretization. Further, the proposed framework utilizes the space-time buffering concept to formulate ε -neighborhood queries that directly retrieve the ε -neighbors of trajectories and thus avoids computing a trajectory similarity matrix. State-of-the-art trajectory databases and index structures are incorporated to further improve trajectory clustering performance. A comprehensive case study was carried out using an open dataset of 20,161 trajectories. Results show that the proposed framework efficiently executed trajectory clustering on the large test dataset within 3 min. This was approximately 2,700 times faster than existing DBSCAN algorithms. [ABSTRACT FROM AUTHOR]

This study investigates the persistence of gendered choice and use of media, particularly in Japanese domestic settings. It shows how women's significant presence in the digital media environment does not necessarily translate into substantial changes in gendered power dynamics in choosing and using particular media for certain purposes at home. This project's authors, researchers from Argentina, Finland, Israel, Japan, and the US, analyzed interview data from Japan by drawing on the Foucauldian concept of micro-level power, which is categorized into three main types: personal authority, media affordances, and space-time constellations. Through this process, we interviewed 77 individuals, revealing that persistent gendered media choices and use exist in Japan. The project team also looked for similar cases in other countries for further theoretical implications. As a result of this investigation, we argue that the patriarchy continues to influence women's choice and use of media at home even in this media-saturated digital age. Our interview data show that "old media" such as radio, television, newspaper, and magazines not only mediate information and entertainment contents at home, but also structure people's quotidian use of media, both old and new, and sustains existing gendered assumptions and values. [ABSTRACT FROM AUTHOR]

The transmission rate of COVID-19 varies by location and time. A proper measure of the transmissibility of an infectious disease should be place- and time-specific, which is currently unavailable. This research aims to better understand the spatiotemporally changing transmissibility of COVID-19. It contributes to COVID-19 research in three ways. First, it presents a generally applicable modeling framework to estimate the transmissibility of COVID-19 in a specific place and time based on daily reported case data, called space-time effective reproduction number, denoted as R s t. Then, the developed model is used to create a spatiotemporal data set of R s t values at the county level in the United States. Second, it investigates relationships between R s t and dynamically changing context factors with multiple machine learning and spatial modeling techniques. The research examines the relationships from a cross-sectional perspective and a longitudinal perspective separately. The longitudinal view allows us to understand how local human dynamics and policy factors influence changes in R s t over time in the place, whereas the cross-sectional view sheds light on the demographic, socioeconomic, and environmental factors behind spatial variations of R s t at a specific time slice. Some general trends of the relationships are found, but the level of impact by each context factor varies geographically. Third, the best performing local longitudinal models have promising potential to simulate or forecast future transmissibility. The random forest and the exponential regression models based on time-series data gave the best performances. These models were further evaluated against ground truth data of county-level reported cases. Their good prediction accuracies in the case study prove that these machine learning models are promising in their ability to predict transmissibility in hypothetical or foreseeable scenarios. [ABSTRACT FROM AUTHOR]

This paper proposes a stochastic reaction–diffusion predator–prey system with fear under the interference of space-time white noise by using the related theories of stochastic partial differential equations. The motivation of this paper is twofold: (i) mathematically, to try to investigate the effects of environmental noise and diffusion on population dynamics; (ii) biologically, to study how environmental noise affects the permanence of species. First, we analyse the well-posedness of solutions. Then sufficient conditions for extinction and permanence of prey and predator populations are derived. Moreover, we present the existence and uniqueness of stationary distribution of this system. Finally, based on numerical simulations and theoretical analysis, it is revealed that (i) high-intensity white noise can lead to the extinction of predator populations; (ii) low-intensity white noise may prolong the period of periodic solutions. This study provides new theoretical guidance for exploring ecological issues in the face of environmental disturbance and spatial diffusion. [ABSTRACT FROM AUTHOR]

We argue that, insofar as one accepts either supersubstantivalism or strong composition as identity for the usual reasons, one has (defeasible) reasons to accept the other as well. Thus, all else being equal, one ought to find the package that combines both views – the Identity Package – more attractive than any rival package that includes one, but not the other, of either supersubstantivalism or composition as identity. [ABSTRACT FROM AUTHOR]

The current paper develops and analyzes a numerical scheme for the space–time fractional stochastic nonlinear diffusion wave equations. The implicit scheme is based on the matrix transform technique for discretizing the Riesz-space fractional derivative, (3 − α) -order approximation to the Caputo-fractional derivative in time and Taylor's series method to linearize the nonlinear source term, and has been successfully applied to solve a class of nonlinear fractional diffusion wave equation. We prove that the implicit scheme is convergent with β-order in space and (3 − α) order in time, respectively. The optimum error estimates in the temporal-spatial direction and unconditional stability of the implicit scheme have been theoretically investigated. Moreover, several specific numerical experiments confirm the consistency and high efficacy of the provided algorithms, which minimizes the computational costs. [ABSTRACT FROM AUTHOR]

The way in which individualised child agency is already 'given' ontologically in digital play research profoundly affects epistemology: how data is produced, analysed and interpreted. Co-created as part of a large-scale international study is a photograph 'of' South African six-year-old Zuko playing with Lego bricks. The agential realist diffractive reading of the photo as phenomenon traces transdisciplinary what is already at play materially and discursively in its specificity. Benefitting from recent work by feminist philosopher and quantum physicist Karen Barad and other agential realists, this article foregrounds the distinct contribution agential realism can make in children's geographies. Moving away from either zooming in objects, or subjects when analysing data disrupts the adult-human gaze and brings into focus the apparatuses that measure and the relational spacetime entanglements objects are always already part of. Doing justice to the complexity of reality reconfigures digital play and agency as intra-actively relational – essential for reimagining more equitable futures in resource-constrained environments. [ABSTRACT FROM AUTHOR]

This article presents a statistic to identify the proportional intensity of an area to belong to a space-time cluster, which is very important in spatial statistics. A significant extension of the so-called F -function has been described in detail, which, associated with new technology, allows the evaluation of the intensity of change moments in the time process and outline possible occurrences of clusters. The justification of the study is performed through an extensive review of the current literature of the area. The developed algorithms are detailed via computational experiments with simulated data. Real situations are presented and discussed in detail. Finally, topics for future research are indicated. [ABSTRACT FROM AUTHOR]

In this article, we present a new tensor that generalizes the conharmonic curvature tensor, termed the ψ-conharmonic curvature tensor. In the first part, we derive some fundamental geometrical properties of a pseudo ψ-conharmonically symmetric manifold (briefly,) and give some fascinating outcomes. Among others, we establish that an Einstein manifold is of zero scalar curvature. Besides, we investigate ψ-conharmonically flat perfect fluid and spacetimes, respectively. As a result, we acquire some significant theorems. Finally, we construct several non-trivial examples to establish the existence of. [ABSTRACT FROM AUTHOR]

In this paper, all derivations of the Schrödinger algebra in (n + 1) -dimensional space-time of the Schrödinger Lie group are determined. As applications, all biderivations are obtained. Finally, as applications of biderivations, the linear commuting maps and commutative post-Lie algebra structures on this algebra are given. [ABSTRACT FROM AUTHOR]

The space–time perturbed fractional Gerdjikov–Ivanov equation is the main topic of this work, together with quintic nonlinearity and self-steepening, as it involves several intricate physical phenomena including nonlinearity, self-steepening and fractional calculus, where the fractional derivative is described by employing a conformable derivative. In addition, the governing equation is transformed into an integer-order ordinary differential equation by using an appropriate fractional complex transformation. Under certain restrictions, a direct algebraic method is employed to investigate the structures of chirp soliton solutions enfolding hyperbolic functional terms. The dynamic behaviour and bifurcation of equilibria of the system are thoroughly examined; chirp soliton solutions under specified constraints are investigated and the evolving profiles of the obtained solutions are visualized. Moreover, this research offers valuable perspectives on the behaviour of chirp solitons under specific conditions, which have practical applications in nonlinear physical systems and optical communication systems. The significant contribution of this work is the investigation and obtaining of novel chirp soliton solutions with hyperbolicfunctional terms under particular limitations using a novel approach. It further extends the prior approaches by treating difficult fractional differential equations from a fresh angle, offering new tools, and closely examining soliton solutions. [ABSTRACT FROM AUTHOR]

This essay weaves together elements of the concepts of spacetime, demons and the U.S. popular culture concept of demon time to postulate the end of the world and bring a conclusion to white supremacist and anti-African American worlds. Topics discussed are Black posthumanism as the foundation of Black transhumanism or technological materialization, time dilation as an element for understanding how African Americans experience time, and demon time as a way to bring African American realities.

Human movement takes place in both space and time so that measures of movement accuracy in space are made with respect to time, and vice-versa providing a foundation to the proposal of the complementarity of spatial and temporal error in aiming movements. We examined this hypothesis in both the standard Fitts and Peterson discrete movement speed-accuracy protocol that requires moving to stop within a fixed spatial target (distance (D) with target bandwidth (WD) in an emergent movement time (T) and, also in the reciprocal and novel space-time protocol introduced here that required moving for a fixed temporal target goal T with bandwidth of WT with an emergent D. Experiment 1 examined a range of D conditions (45, 100, 180, 280, and 405 mm with bandwidth WD ±5 mm) within the Fitts' Law discrete spatial accuracy protocol to provide compatible spacetime boundary conditions for the reciprocal spacetime protocol in Experiment 2 that examined the effect of target time (T − 250, 460, 670, and 880 ms each with bandwidth WT ±50 ms) on the emergent D. The findings showed that the spatial and temporal error profiles in Experiment 2 were consistent with exchanging D and T in Fitts' Law Equation. This provides evidence for the reciprocal nature of the spacetime error functions in Fitts' type movement aiming protocols and is compatible with the reciprocal profiles of spatial and temporal errors in other classes of movement aiming tasks. [ABSTRACT FROM AUTHOR]

The aim of this paper is to explain the significance of Alfred A. Robb's philosophy of time stemming from his interpretation of relativity theory; and at the same time, to investigate the reasons for the failure of his philosophical contemporaries to appreciate its significance, with special attention to its reception on Russell's part. The study of Russell's reaction to Robb exposes shortcomings in Russell's own philosophy of time, which has been extremely influential through the years. It also highlights the philosophical differences between Minkowski and Robb, the shared idealistic premises of Russell and McTaggart, and the confluences between the views of Russell, Eddington and McTaggart. The paper closes with an account of how Robb's interpretation has been vindicated by its adoption in modern physics. [ABSTRACT FROM AUTHOR]

We consider the operator Δ (α , β) − I , where Δ (α , β) is the three term recurrence relation for the Jacobi polynomial R n (α , β) (x) normalized at the point x = 1 and I is the identity operator acting on N . Knowing that for α ≥ β ≥ − 1 2 , these polynomials satisfy a product formula which provides a hypergroup structure on N , we use the tools of harmonic analysis on this hypergroup to solve the space-time fractional diffusion equation { D t σ u (n , t) = − (− Δ (α , β) ) s u (n , t) , t > 0 , n ∈ N , u (n , 0) = f (n). Here, 0 < s , σ ≤ 1 , D t σ is the Caputo time fractional derivative of order σ. The solution is given by f ∗ G σ , s (α , β) (⋅ , t) (n) , G σ , s (α , β) (n , t) being the fundamental solution expressed in terms of Mittag-Leffler function and ∗ is the convolution on the hypergroup N . We prove that, for 0 < s < σ ≤ 1 , G σ , s (α , β) (n , t) is nonnegative and we give some of its properties. Next, we study the one parameter operators associated with this fundamental solution. [ABSTRACT FROM AUTHOR]

This paper intends to be shared as a personal testimony and hopes to be taken by the reader as a lived experience rather than mere academic research. Thus, although the text is based on historical evidence, the notion of "history" should not be understood as a linear succession of events but more as cyclical stories and times that are constantly Weaving themselves together into a present. Weaving, as a structuring activity generated by body-mind, space-time, human-nature relationships, has precisely structured natural, social, political, and cultural ecosystems of human life since the beginning of time. Weaving is, therefore, one of the primary expressive means that puts culture into practice. This essay aims to revive the paradoxical path—shaped by stories and processes of migration, colonization, and decolonization—that led to my reunion with Andean Weaving outside my country. Finding alive the voices that gave birth to the material language of my Indigenous ancestors through the textile medium provoked a revolution on my way of being, feeling, thinking, and making. Therefore, this work attempts to develop critical feel-thinking around the colonial system that calls itself "modern" and has perpetuated the dominant Western culture against the Indigenous. I welcome the reader to navigate throughout these lines with an open perception of the notions of modernity/tradition, art/craft, body/mind, past/present, reverting and expanding its binary condition imposed by colonial power structures. [ABSTRACT FROM AUTHOR]

This article, which draws on three waves (2005, 2010, 2015) of the European Working Conditions Survey, examines the nature and prevalence of different job types in a representative sample of employees in 30 European countries (N = 59,839) and investigates their change over time. Using self-organizing map, sampled employees were first grouped into seven job types, based on similar job features in the following dimensions: physical environment, work intensity, working time quality, social environment, skill and discretion, and earnings and prospects. Subsequently, the resulting job types were validated by linear regression models on outcomes that are indicative of job quality, such as well-being and job satisfaction. Finally, space-time variations in the distribution of job types were explored using a two-stage formulation model that contrasted universalistic and institutional explanations of change. Results indicate that three clusters of countries could be distinguished, which only partially fit into existing regime classifications: i) the Northern cluster (Scandinavian countries); ii) the Central and Western cluster (Belgium, the Netherlands, Luxembourg, France, Germany, Austria, Slovenia, Estonia, but also the UK, Ireland and Malta); and iii) the Southern and Eastern cluster (Mediterranean countries including Cyprus and Turkey, the former socialist EU member states, Latvia, and Lithuania). These clusters present specific patterns of change in the distribution of job types that are more closely related to the change in the national economic situation and the employment structure than to institutional variation. [ABSTRACT FROM AUTHOR]

We present a pair of adjoint optimal control problems characterizing a class of time-symmetric stochastic processes defined on random time intervals. The associated PDEs are of free-boundary type. The particularity of our approach is that it involves two adjoint optimal stopping times adapted to a pair of filtrations, the traditional increasing one and another, decreasing. They are the keys of the time symmetry of the construction, which can be regarded as a generalization of 'Schrödinger's problem' (1931–1932) to space-time domains. The relation with the notion of 'Hidden diffusions' is also described. [ABSTRACT FROM AUTHOR]

We devise multigrid preconditioners for linear-quadratic space-time distributed parabolic optimal control problems. While our method is rooted in earlier work on elliptic control, the temporal dimension presents new challenges in terms of algorithm design and quality. Our primary focus is on the cG(s)dG(r) discretizations which are based on functions that are continuous in space and discontinuous in time, but our technique is applicable to various other space-time finite element discretizations. We construct and analyse two kinds of multigrid preconditioners: the first is based on full coarsening in space and time, while the second is based on semi-coarsening in space only. Our analysis, in conjunction with numerical experiments, shows that both preconditioners are of optimal order with respect to the discretization in case of cG(1)dG(r) for r = 0, 1 and exhibit a suboptimal behaviour in time for Crank–Nicolson. We also show that, under certain conditions, the preconditioner using full space-time coarsening is more efficient than the one involving semi-coarsening in space, a phenomenon that has not been observed previously. Our numerical results confirm the theoretical findings. [ABSTRACT FROM AUTHOR]

The classic approach to research on toponymy is limited to a linguistic focus. This reductionism has had a negative impact on the study of the toponymy of intercultural and indigenous territories, as in the case of the northern Patagonia. Based on a two-year ethnographic study in northern Patagonia, this article analyzes the socio-spatial dimension of Mapuche toponymy, through a mixed methodology involving both data collection and analysis, and an ethnographic approach. The article analyzes how these toponyms emerge from a variety of socio-spatial practices and meanings that are not only intertwined, but also involve several social, environmental, and political dimensions. We argue that the study of indigenous toponymy as a space-time compression entails an ontological opening of toponymy based on the process of inhabiting place. In this regard, the paper discusses the importance of understanding indigenous toponymy as a historically situated process. [ABSTRACT FROM AUTHOR]

In this paper, two localized meshless schemes using polynomial basis functions have been presented for solving space–time problems. The proposed methods are especially attractive for solving time-dependent problems in 3D spacious domain. The results showed the simplicity and high accuracy of the proposed methods. Six numerical examples are given to illustrate the effectiveness of the proposed methods. We also presented the pros and cons of the proposed methods by comparing to the results of some recent publications using global polynomial basis functions and localized radial basis functions. [ABSTRACT FROM AUTHOR]

The problem of urban crashes brings huge challenges and threats to local police and governments, especially in many cities in developing countries such as China. To reduce the frequency and severity of urban crashes, the local government in China has gradually taken interest in conducting detailed actions of traffic safety improvement at the microzone-level. Therefore, the primary goal of this study is to try a new method in spatiotemporal data mining techniques, the space-time cube method, to find high-risk crash spots at the spatiotemporal level and to obtain their spatiotemporal evolution patterns. The cumulative frequency curve method was performed to identify high-risk crash spots, and the contributory factors of forming these spots were analyzed by the latent class analysis method. The results showed that: (1) key parameters' selection is crucial in the space-time cube construction; (2) the exit ramp gore point in interchanges, intersections, and entrances of neighborhoods were prone to have many high-risk crash spots at the spatiotemporal scale; and (3) locations with consecutive, persistent, and sporadic hotspots patterns need different risk monitoring strategies and traffic safety improvement. The feasibility and advantages of the space-time cube method in hotspots identification at the microzone-level were confirmed. [ABSTRACT FROM AUTHOR]

Multigrid methods, algebraic or geometric, commonly suffer from high frequency residuals after prolongation. This paper develops a stable approach to remove high frequency residuals for geometric multigrid methods for solving nonlinear advection–diffusion problems with degenerate coefficients. Here, a local problem is treated by optimization on subdomains with mesh refinements. Newton's method is utilized in the procedure and the iteration is completed when the residual in the subdomain is reduced to the given magnitude, usually set to be the average of residuals in the non-high-frequency domains. An oversampling technique is employed to further improve the stability by providing a definite flow path in regions where coefficients have high contrast and complex structures. Removing high frequency residuals before continuing the global Newton iteration improves global convergence behavior. [ABSTRACT FROM AUTHOR]

In this paper, a unified M-estimation method in Yang (2018) is extended to the matrix exponential spatial dynamic panel specification (MESDPS) with fixed effects in short panels. Similar to the STLE model which includes the spatial lag effect, the space-time effect and the spatial error effect in Yang (2018), the quasi-maximum likelihood (QML) estimation for MESDPS also has the initial condition specification problem. The initial-condition free M-estimator in this paper solves this problem and is proved to be consistent and asymptotically normal. An outer product of martingale difference (OPMD) estimator for the variance-covariance (VC) matrix of the M-estimator is also derived and proved to be consistent. The finite sample property of the M-estimator is studied through an extensive Monte Carlo study. The method is applied to US outward FDI data to show its validity. [ABSTRACT FROM AUTHOR]

Let wF, wC+, and wC− be three distinct worlds, each of which contains only a single point-sized material particle, and in each of which spacetime is: uniformly flat, constantly positively curved, and constantly negatively curved, respectively. By the relationist's lights, these worlds seem to be qualitatively identical. Nevertheless, for each world, there are propositions concerning possible arrangements of material points that are true in that world, but false in the other two. I argue that, surprisingly, the relationist can ground these differences in the distinct non-modal and intrinsic relations that are instantiated in each of wF, wC+, and wC–. [ABSTRACT FROM AUTHOR]

In high-frequency surface wave radar (HFSWR) systems, the main-lobe of the receiving angle spectrum suffers from severe broadening due to a small-array aperture effect. This broadening causes more clutter components to be mixed into the main-lobe, resulting in target vessels more prone to be submerged in the clutter. This problem severely affects the target detection performance. A reduction in the number of array elements decreases the degrees of freedom (DOF), making clutter suppression more difficult. Space-time adaptive processing (STAP) has recently become a crucial tool for clutter suppression in advanced HFSWR systems, using two-dimensional data to increase DOF. Focusing on low DOF and typical nonhomogeneous clutter with high energy, this study proposes a STAP clutter suppression method by estimating clutter components accurately in the space-time domain based on sparse representation in few snapshots. The experimental results verify that the proposed algorithm provides high suppression performance for measured clutter. [ABSTRACT FROM AUTHOR]

Ladyman and Presnell have recently argued that the Hole argument is naturally resolved when spacetime is represented within homotopy type theory rather than set theory. The core idea behind their proposal is that the argument does not confront us with any indeterminism, since the set-theoretically different representations of spacetime involved in the argument are homotopy type-theoretically identical. In this article, we will offer a new resolution based on ZFC set theory to the argument. It neither relies on a constructive-intuitionistic form of mathematics, as used by Ladyman and Presnell, nor is foundationally problematic, such as the existing set-theoretic suggestions. [ABSTRACT FROM AUTHOR]

Material culture is an extension of spatial–temporal perceptions and behaviour. The nature of the manner in which rhetorical material is woven into visual narrative become symbolic expressions of material assembly. Mikhail Bakhtin referred to such material assembly as "flesh" in the instance of the novel. In this article, I will extend Bakhtin's notion of "flesh" to film and demonstrate that Edward Hall's theory of mono-chronic and poly-chronic time apply to the materialisation of narrative flesh in the films discussed herein. [ABSTRACT FROM AUTHOR]

Machine learning (ML) interpretability has become increasingly crucial for identifying accurate and relevant structural relationships between spatial events and factors that explain them. Methodologically aspatial ML algorithms with an apparent high predictive power ignore non-stationary domain relationships in spatio-temporal data (e.g. dependence, heterogeneity), leading to incorrect interpretations and poor management decisions. This study addresses this critical methodological issue of 'interpretability' in ML-based modeling of structural relationships using the example of heterogeneous drivers of wildfires across the United States. Specifically, we present and evaluate a spatio-temporally interpretable random forest (iST-RF) that uses spatio-temporal sampling-based training and weighted prediction. Although the ultimate scientific objective is to derive interpretation in space-time, experiments show that iST-RF can improve predictive accuracy (76%) compared to the aspatial RF approach (70%) while enhancing interpretations of the trained model's spatio-temporal relevance for its ensemble prediction. This novel approach can help balance prediction and interpretation with fidelity in a spatial data science life cycle. However, challenges exist for predictive modeling when the dataset is very small because in such cases locally optimized sub-model's prediction performance can be suboptimal. With that caveat, our proposed approach is an ideal choice for identifying drivers of spatio-temporal events at country- or regional-scale studies. [ABSTRACT FROM AUTHOR]

A generalization of the ultra-hyperbolic time-fractional diffusion-wave equation introduced by the author in Dorrego [The Mittag–Leffler function and its application to the ultra-hyperbolic time-fractional diffusion-wave equation. Integral Transforms Spec. Funct. 2016;27(5):392–404] is presented and studied. The results obtained here extend the previous to the whole space R n . The problem is solved by applying the integral transforms method and the analytical solution is given by the Fox H-function. Some interesting particular cases are analysed. [ABSTRACT FROM AUTHOR]

There is a long-held view that discrete movements aimed to a target are composed of a sequence of movement units (sub-movements) that have different roles in motor control (e.g., initial impulse, error correction and movement termination) depending on the task constraints (e.g., spatial-temporal requirements). Here we report findings from the manipulation of vision/no-vision on the prevalence and type of sub-movements in discrete movement tasks over a range of space-time task criteria. The presence of vison resulted in longer movement times compared to the no-vision counterpart in time-matching tasks. A similar vision effect was observed in the highest Index of Difficulty for time-minimization tasks. Conditions that resulted/required longer movement times demonstrated more pre-velocity-peak and post-velocity-peak types of sub-movements whereas short movement times increased the likelihood of overshooting sub-movements. The present study results are consistent with the idea that movement time is the variable associated with changes in sub-movement profiles. [ABSTRACT FROM AUTHOR]

This article explores how young people in Sweden talk about and understand violence, with a particular emphasis on how violence, gender, space and time are co-constructed in this discourse. We found that young people display an ambivalent attitude to violence, reinforcing several contradictory discourses of violence. Young people adopt various understandings that place violence differently in time (ongoing vs. past) and space (distant/absent vs. close/present). They discursively construct the school as a non-violent space while considering digital spaces to be violent. Yet, they still find that violence occurs at different places and times at school. These 'discursive manoeuvres' highlight how views on violence that territorialises and re-territorialises places as being 'safe' or 'unsafe' is part of the gendered spatial regulation of young people's lives. By specifically analysing time and space in young people's discourse on violence, this article contributes to research on their perspectives on gendered violence. [ABSTRACT FROM AUTHOR]