Access Graph Research Articles

Metroticket approach in a retrospective cohort study to predict overall survival after surgical resection for intermediate stage hepatocellular carcinoma.

Surgical resection is a curative therapy for early-stage hepatocellular carcinoma (HCC) patients meeting the Milan criteria as well as a widely used therapy in intermediate-stage HCC. However, intermediate-stage HCC encompasses a wide spectrum of disease and there is a lack of good predictive models for the long-term clinical outcome of HCC patients currently. Here, we adopt Mazzaferro's Metroticket 2.0 to create a robust survival prediction model for intermediate-stage HCC patients undergoing surgical resection. Our algorithm considers age, AFP levels, ALBI score, and nodule size/number to generate survival estimates in an accessible graph format. Importantly, our model surpasses the American Joint Committee on Cancer staging model and was validated with independent US patient data. We conducted a retrospective analysis of OS and RFS in early- and intermediate-stage HCC patients treated with liver resection, including a training cohort in Singapore and a validation cohort in North Carolina, USA. We recorded 278 deaths (35.0%) and 428 patients (53.9%) in the first 5-years after surgical resection; higher ALBI score, higher lnAFP, more advanced age and higher tumour burden index were identified as significant parameters. The overall predictive capability of our model, with the inclusion of AFP, is reflected with a UNO's C-statistic of 0.655, which is 1.11 times better than the 0.5895 C-statistic of the 8th AJCC TNM Staging model. Our modified Metroticket model allows for more granular and better-informed prognostication. This will help surgeons and patients make accurate comparisons between the clinical outcomes of surgical resection and other non-surgical treatments.

Cohen–Macaulay binomial edge ideals in terms of blocks with whiskers

For a graph [Formula: see text] and the binomial edge ideal [Formula: see text] of [Formula: see text], Bolognini et al. have proved the following: [Formula: see text] is strongly unmixed [Formula: see text][Formula: see text] is Cohen–Macaulay [Formula: see text][Formula: see text] is accessible. Moreover, they have conjectured that the converse of these implications is true. Accessible and strongly unmixed properties are purely combinatorial. We give some motivations to focus only on blocks with whiskers for the characterization of all [Formula: see text] with Cohen–Macaulay [Formula: see text]. We show that accessible and strongly unmixed properties of [Formula: see text] depend only on the corresponding properties of its blocks with whiskers and vice versa. We give a new family of graphs whose binomial edge ideals are Cohen–Macaulay, and from that family, we classify all [Formula: see text]-regular [Formula: see text]-connected graphs, with the property that, after attaching some special whiskers to it, the binomial edge ideals become Cohen–Macaulay. To prove the Cohen–Macaulay conjecture, it is enough to show that every non-complete accessible graph [Formula: see text] has a cut vertex [Formula: see text] such that [Formula: see text] is accessible. We show that any non-complete accessible graph [Formula: see text] having at most three cut vertices has a cut vertex [Formula: see text] for which [Formula: see text] is accessible.

Efficient Calculation and Visualization of Energy Grade Line (EGL) and Hydraulic Grade Line (HGL) in Fluid Flow Systems

The goal of this project is to use MATLAB software to efficiently calculate and visually represent the Energy Grade Line (EGL) and Hydraulic Grade Line (HGL) in fluid flow systems. This work serves as a practical showcase of our how MATLAB can be used to make Bernoulli calculations in the realm of civil engineering. In addition, the incorporation of Building Information Modeling (BIM) offers the potential to further enhance the design and analysis of fluid flow systems. The Energy Grade Line (EGL) holds a vital position in fluid mechanics, acting as a representation of a fluid's energy as it moves through a conduit. This blend of pressure, velocity, and elevation energy provides crucial insights into the behavior and characteristics of the fluid throughout its course. For engineers, the EGL is an essential tool, aiding in the analysis of fluid flow systems, identification of energy losses, and optimization of hydraulic structures. Furthermore, the Hydraulic Grade Line (HGL) represents another critical concept in fluid mechanics, graphically illustrating the pressure head of fluid along a specified route. It offers a clear depiction of energy distribution within a fluid flow system, accounting for the sum of pressure and elevation heads. Engineers heavily rely on the HGL to inspect pressure fluctuations, detect potential issues like pressure drops or excessive velocities, and make informed decisions to ensure fluid flow's efficiency and reliability. Thorough testing and implementation revealed that, with precise configuration of the MATLAB environment code, our code achieves high accuracy calculations for Energy Grade Line (EGL) and Hydraulic Grade Line (HGL) values. This setup also enables the generation of clear graphical representations, providing engineers with a reliable and visually accessible graph for fluid flow system analysis.

Extracting real estate values of rental apartment floor plans using graph convolutional networks

Access graphs that indicate adjacency relationships from the perspective of flow lines of rooms are extracted automatically from a large number of floor plan images of a family-oriented rental apartment complex in Osaka Prefecture, Japan, based on a recently proposed access graph extraction method with slight modifications. We define and implement a graph convolutional network (GCN) for access graphs and propose a model to estimate the real estate value of access graphs as the floor plan value. The model, which includes the floor plan value and hedonic method using other general explanatory variables, is used to estimate rents, and their estimation accuracies are compared. In addition, the features of the floor plan that explain the rent are analyzed from the learned convolution network. The results show that the proposed method significantly improves the accuracy of rent estimation compared to that of conventional models, and it is possible to understand the specific spatial configuration rules that influence the value of a floor plan by analyzing the learned GCN.

The typology of courtyard space in Najdi Architecture, Saudi Arabia: a response to human needs, culture, and the environment

ABSTRACT This study seeks to identify the significant characteristics of the traditional Najdi courtyard in Saudi Arabia in order to comprehend the typology and applicability of courtyard patterns in Najdi dense urban neighborhoods. The study includes a literature review that investigates the socio-cultural influences on courtyard typology and the typological implications of courtyard residences at both the building and urban scales. The study also includes a case study of six Najdi courtyard residences in three settlements in the central region that analyzes the patterns, characteristics, and spatial qualities of these courtyards. The ethnographic approach is used to observe and document a culture, society, or other phenomenon related to the study objectives through participant observation and interviews, as well as making use of the Space Syntax “justified access graphs” method to understand and examine the organization and spatial order of the traditional dwelling. The study indicates that the courtyard acts as a holistic space and place within the home; however, the features of individual courtyards may vary based on geographical and environmental setting. The conclusion of the research is that courtyard typologies have the capacity to satisfy the enduring cultural, social, and climatic demands of residents and hence might be implemented in contemporary urban contexts. The findings of this research suggest that courtyard typology has the potential to create an environment of comfort, privacy, and special efficiency for modern urban households.

Traffic demand prediction based on spatial-temporal guided multi graph Sandwich-Transformer

The ability of spatial-temporal traffic demand prediction is crucial for urban computing, traffic management and future autonomous driving. In this paper, a novel Spatial-Temporal Guided Multi-graph Sandwich-Transformer (STGMT) is suggested to address the ubiquitous spatial-temporal heterogeneity in traffic demand forecasting. Compared to the original Transformer, we employ Time to Vector (Time2Vec) and Node to Vector (Node2Vec) in the embedding layer to obtain universal representations for temporal nodes and spatial nodes, respectively, which are then combined to form Spatial-Temporal Embedding (STE) blocks. The STE guides the attention mechanism, maintaining a unique parameter space for spatial-temporal nodes and enabling the learning of node-specific patterns. In STGMT, we develop Multi-head Temporal Attention (MTA) and Multi-head Temporal Interactive Attention (MTIA) for extracting temporal features, while Multi-head Spatial Attention (MSA) is employed for extracting spatial features. Furthermore, MSA incorporates both the accessibility graph determined by road topology and the similarity graph determined by specific traffic events to characterize the pairwise relationships among spatial nodes. Various attentions and feed-forward layers are rearranged and combined to form the Sandwich-Transformer. Extensive experiments are conducted on public datasets of node-level tasks of two different types (highway and urban) and indicate that the STGMT outperforms state-of-the-art models. The proposed STGMT effectively addresses the ubiquitous spatial-temporal heterogeneity challenge in traffic demand forecasting, thereby enhancing the accuracy of traffic demand prediction and offering valuable guidance for traffic planning and operations. Our code and data are open source at https://github.com/YanJieWen/STGMT-Tensorflow-implementation.

A Stallings type theorem for quasi-transitive graphs

We consider locally finite, connected, quasi-transitive graphs and show that every such graph with more than one end is a tree amalgamation of two other such graphs. This can be seen as a graph-theoretical version of Stallings' splitting theorem for multi-ended finitely generated groups and indeed it implies this theorem. Our result also leads to a characterisation of accessible graphs. We obtain applications of our results for planar graphs (answering a variant of a question by Mohar in the affirmative) and graphs without thick ends.

Everything you control is not everything: Achieving intention-concealed visit on social networks

With the flourishment of Artificial Intelligence (AI), the quality of services on online social networks (OSNs) has improved tremendously. Through the introduction of AI into OSNs, providers enhance the users experience. However, the risk of data misuse has also been magnified. And there has been a trend towards users’ mistrust when it comes to sharing their true intention on OSN platforms, primarily because of privacy concerns. In this paper, we propose an effective intention-concealing visitation framework named Aviv, which acts as a credible and private third-party where it generates artificial intention-concealed browsing (AICB trajectories) for users to conceal their true intentions. The browsing trajectory is a sequence composed of blogs, bloggers, news, or a mixture containing visitable content. Specifically, Aviv first extracts accessible graphs composed of visitable contents from applied OSN platforms. Then an elaborate and personalized divert scoring process is conducted to measure optional decoy visits’ effectiveness. Finally, using the divert scoring values, elaborate and personalized decoy visits are picked out, Aviv composes AICB trajectories with true intentions and picked decoy visits. Aviv is implemented as a credible private third-party and tested on a real OSN, the performance evaluation results show that Aviv is effective and efficient.

IFC BIM Model Enrichment with Space Function Information Using Graph Neural Networks

The definition of room functions in Building Information Modeling (BIM) using IfcSpace entities is an important quality requirement that is often not fulfilled. This paper presents a three-step method for enriching open BIM representations based on Industry Foundation Classes (IFC) with room function information (e.g., kitchen, living room, foyer). In the first step, the geometric algorithm for detecting and defining IfcSpace entities and injecting them into IFC models is presented. After deriving the IfcSpaces, a geometric method for calculating the graph of connections between spaces based on accessibility is described; this information is not explicitly stored in IFC models. In the final step, a graph convolution-based neural network using the accessibility graph to classify the IfcSpace entities is described. Local node features are automatically extracted from the geometry and neighboring elements. With the help of a Graph Convolutional Network (GCN), the connection and spatial context information is utilized by the neural network for the classification decision, in addition to the local features of the spaces which are more commonly used. To evaluate the classification accuracy, the model was tested on a set of residential building IFC models. A weighted version of the common GCN was implemented and tested, resulting in a slight improvement in the classification accuracy.

Method of intermodal accessibility graph construction

The article presents a method for modelling an intermodal graph of accessibility of urban areas. The accessibility of the city's territories is usually understood as a zone where a person can walk or get by transport for a certain time from a given point. Accessibility assessment is fundamental in the problems of computational urbanism and is used for a variety of applied spatial indexes and estimates. At the same time, traditional methods of assessing the transport accessibility of the urban environment require the creation of models of transport systems of the studied city, which is associated with significant costs. The situation is complicated by the peculiarities of the urban environment and the need to consider the movement of different types of transport in combination with walking. The method proposed in this article uses an alternative approach to assessing the accessibility of urban areas based on the construction of an intermodal accessibility graph. This makes it possible to use this algorithm in solving applied urban problems without the need to build complex transport models.

Cohen–Macaulay binomial edge ideals and accessible graphs

The cut sets of a graph are special sets of vertices whose removal disconnects the graph. They are fundamental in the study of binomial edge ideals, since they encode their minimal primary decomposition. We introduce the class of accessible graphs as the graphs with unmixed binomial edge ideal and whose cut sets form an accessible set system. We prove that the graphs whose binomial edge ideal is Cohen–Macaulay are accessible and we conjecture that the converse holds. We settle the conjecture for large classes of graphs, including chordal and traceable graphs, providing a purely combinatorial description of Cohen–Macaulayness. The key idea in the proof is to show that both properties are equivalent to a further combinatorial condition, which we call strong unmixedness.

Topology characteristic analysis of vehicular ad hoc network based on time-varying complex network

The dynamic network topology of the Vehicular Ad Hoc Network (VANET) directly affects network performances. The VanetMobiSim software was used to study the dynamic topology of VANET in detail. A time-varying model of VANET was built. First, the information transmission model of VANET was established on the basis of the time-varying network theory. The evolution of VANET characteristic parameters in a time-varying process was stimulated by using the information transmission time τ and the maximum tolerated delay time δ accessibility graph. Then, we perform mathematical analysis of the relations of (τ, δ) to the out-degrees, average packet accessibility, and asymmetry ratio. Finally, the relations of the node communication radius to the global efficiency and the average harmonic mean of the distances were analyzed. The results indicated that the time-varying accessibility graph made VANET information transmission more efficient; reducing the information transmission time τ or increasing the maximum tolerated delay time δ tends to bring out the improving temporal connectivity of the whole network, thus improving the efficiency of packet transmission.

Authoring consistent landscapes with flora and fauna

We present a novel method for authoring landscapes with flora and fauna while considering their mutual interactions. Our algorithm outputs a steady-state ecosystem in the form of density maps for each species, their daily circuits, and a modified terrain with eroded trails from a terrain, climatic conditions, and species with related biological information. We introduce the Resource Access Graph, a new data structure that encodes both interactions between food chain levels and animals traveling between resources over the terrain. A novel competition algorithm operating on this data progressively computes a steady-state solution up the food chain, from plants to carnivores. The user can explore the resulting landscape, where plants and animals are instantiated on the fly, and interactively edit it by over-painting the maps. Our results show that our system enables the authoring of consistent landscapes where the impact of wildlife is visible through animated animals, clearings in the vegetation, and eroded trails. We provide quantitative validation with existing ecosystems and a user-study with expert paleontologist end-users, showing that our system enables them to author and compare different ecosystems illustrating climate changes over the same terrain while enabling relevant visual immersion into consistent landscapes.

Dwelling form and culture in the traditional Najdi built environment, Saudi Arabia

PurposeThis study examines the built environment in the preserved historic settlements of the Najd region of Saudi Arabia, providing insight into shared core concepts and forms that were commonly shared across the settlement's dwellings before the Kingdom's period of modernization.Design/methodology/approachSpace syntax convex mapping and the justified access graphing as the main techniques to examine several internal elements at the building level. The study created elements such as connectivity, access graphs and depth graphs to understand the integration and placement of these elements to overcome surrounding forces. Also, the author combined graphical architectural analysis with space syntax techniques to understand the spatial and physical integration in three-dimensional space. This helped to establish a link between what is two-dimensional (the building layout) with what is three-dimensional (the physical form).FindingsThe paper found that the hierarchical order of internal spaces and the order's role in shaping the physical form served to satisfy the social behavior and environmental conditions. As a result, all building elements generated with the guidance of the main culturally rooted in support with internal spaces order. This order of spaces inside the house led the urban spatial hierarchy to connect but not conflict, as the whole process of generating the physical forms is to complement each other and to produce a unified built environment.Research limitations/implicationsThis study is limited to Najdi dwelling form and culture, the author believes expanding the number of study samples in the five traditional settlements or expanding the scope of the study to examine other Saudi regions may result in new findings and insights.Originality/valueThe paper offers and discusses two mechanisms on how to enhance the process of designing modern houses in similar cultures or elsewhere in the world. Also, how traditional dwelling elements generated with the guidance of the main, culturally rooted values and beliefs, in support of the internal spatial order.

An application specific dynamic behaviour model using function-call sequence and memory access-graph for execution integrity verification

Computing systems demand stringent security checks to guard themselves against powerful attack vectors. Deployment of the Control Flow Integrity(CFI) checks limit the control flow of a program to a set of valid destinations, derived from the static analysis of the code. CFI checks guarantee the integrity of the executed code, but, they do not guarantee the integrity of execution, as sophisticated attack vectors create attacks that comply with the normal control flow of the program. This paper proposes an application specific, dynamic, execution integrity verification scheme, to detect static and dynamic integrity breaches. The system builds a behaviour model consisting of function call sequences and memory access graphs, to verify the semantic behaviour exhibited by the application. Dynamic variation of the function behaviour is further recorded as Access Graph Variance Vector (AGVV). Temporal sequencing of function calls, together with the memory access graph comparison, yields a two-level integrity verification system. Apart from detecting the deviations from normal behaviour, our proposed method limits the abnormal behaviour from being propagated. Experimental evaluation of the proposed method using applications from MiBench benchmark suite against static integrity breaches shows cent percent verification accuracy with less than 5% false positive rate. The system also identifies the dynamic integrity violation caused by ROP based attacks from the RIPE benchmark suite, indicating an accuracy of 94.44% against dynamic integrity breaches.

Human centric accessibility graph for environment analysis

Understanding design decisions in relation to the future occupants of a building is a crucial part of good design. However, limitations in tools and expertise hinder meaningful human-centric decisions during the design process. In this paper, a novel Spatial Human Accessibility graph for Planning and Environment Analysis (SHAPE) is introduced that brings together the technical challenges of discrete representations of digital models, with human-based metrics for evaluating the environment. SHAPE: does not need labeled geometry as input, works with multi-level buildings, captures surface variations (e.g., slopes in a terrain), and can be used with existing graph theory (e.g., gravity, centrality) techniques. SHAPE uses ray-casting to perform a search, generating a dense graph of all accessible locations within the environment and storing the type of travel required in a graph (e.g., up a slope, down a step). The ability to simultaneously evaluate and plan paths from multiple human factors is shown to work on digital models across room, building, and topography scales. The results enable designers and planners to evaluate options of the built environment in new ways, and at higher fidelity, that will lead to more human-friendly and accessible environments.

The Concept of Access and the Mechanisms of the Threshold Space in Arab Traditional Built Environment: The Case of Najd, Saudi Arabia

Contemporary built environments experience a vast number of factors due to globalization, which effected and influenced how the built form is generated and used. The relationship between the urban and the building levels is a crucial aspect that needs a thorough investigation to understand how these two levels can integrate and complement the built environment's overall identity. This paper examines the concept of access and its location within the urban fabric and how an access influenced the formation of physical and nonphysical threshold spaces to overcome the number of socio-cultural issues. Space Syntax convex map and justified access graphs were used to understand the connectivity, density, and integration of the access and the threshold space in relation to the overall built form.

A Comparative Analysis of the Spatial Characteristic of Apartment Buildings in Gaziantep, Turkey

This study aims to analyze the planning and design process, basic principles, and the change-transformation process of the apartment type residential buildings in Turkey, Gaziantep. The scope of the research consists of residential buildings built in the post-Republican period in Gaziantep. The basic materials of the research are zoning-city plans, plan explanation reports, plan diagrams of buildings and photographs based on field research. The method of the research is based on a comparative analysis of spatial changes in apartment buildings according to historical background. These changes evaluated from the analysis of a series of variables ranging from parcel-level to plan projects, access graphs to spatial size and ratios. As a result of the study, it is seen that the access graph and space sizes of the apartment-type residential buildings dating back to the 1960s, have significantly changed. However, differences and variations are mostly observed in the first plan typologies and it is noteworthy that this diversity has reduced, and similar plan schemes have been widely used in recent examples.

Concurrency and reachability in treelike temporal networks

Network properties govern the rate and extent of various spreading processes, from simple contagions to complex cascades. Recently, the analysis of spreading processes has been extended from static networks to temporal networks, where nodes and links appear and disappear. We focus on the effects of accessibility, whether there is a temporally consistent path from one node to another, and reachability, the density of the corresponding accessibility graph representation of the temporal network. The level of reachability thus inherently limits the possible extent of any spreading process on the temporal network. We study reachability in terms of the overall levels of temporal concurrency between edges and the structural cohesion of the network agglomerating over all edges. We use simulation results and develop heterogeneous mean-field model predictions for random networks to better quantify how the properties of the underlying temporal network regulate reachability.

IPregel: Vertex-centric programmability vs memory efficiency and performance, why choose?

The vertex-centric programming model, designed to improve the programmability in graph processing application writing, has attracted great attention over the years. Multiple shared memory frameworks that have implemented the vertex-centric interface all expose a common tradeoff: programmability against memory efficiency and performance.Our approach consists in preserving vertex-centric programmability, while implementing optimisations missing from FemtoGraph, developing new ones and designing these so they are transparent to a user’s application code, hence not impacting programmability. We therefore implemented our own shared memory vertex-centric framework iPregel, relying on in-memory storage and synchronous execution. In this paper, we evaluate it against FemtoGraph, whose characteristics are identical, but also an asynchronous counterpart GraphChi and the vertex-subset-centric framework Ligra. Our experiments include three of the most popular vertex-centric benchmark applications over 4 real-world publicly accessible graphs, which cover all orders of magnitude between a million to a billion edges. We then measure the execution time and the peak memory usage. Finally, we evaluate the programmability of each framework by comparing it against the original Pregel, Google’s closed-source implementation that started the whole area of vertex-centric programming.Experiments demonstrate that iPregel, like FemtoGraph, does not sacrifice vertex-centric programmability for additional performance and memory efficiency optimisations, which contrasts with GraphChi and Ligra. Sacrificing vertex-centric programmability allowed the latter to benefit from substantial performance and memory efficiency gains. However, experiments demonstrate that iPregel is up to 2300 times faster than FemtoGraph, as well as generating a memory footprint up to 100 times smaller. These results greatly change the situation; Ligra and GraphChi are up to 17,000 and 700 times faster than FemtoGraph but, when comparing against iPregel, this maximum speed-up drops to 10. Furthermore, on PageRank, it is iPregel that proves to be the fastest overall. When it comes to memory efficiency, the same observation applies; Ligra and GraphChi are 100 and 50 times lighter than FemtoGraph, but iPregel nullifies these benefits: it provides the same memory efficiency as Ligra and even proves to be 3 to 6 times lighter than GraphChi on average. In other words, iPregel demonstrates that preserving vertex-centric programmability is not incompatible with a competitive performance and memory efficiency.