Optimal Dual Schemes for Adaptive Grid Based Hexmeshing

Hexahedral meshes are a ubiquitous domain for the numerical resolution of partial differential equations. Computing a pure hexahedral mesh from an adaptively refined grid is a prominent approach to automatic hexmeshing, and requires the ability to restore the all hex property around the hanging nodes that arise at the interface between cells having different size. The most advanced tools to accomplish this task are based on mesh dualization. These approaches use topological schemes to regularize the valence of inner vertices and edges, such that dualizing the grid yields a pure hexahedral mesh. In this article, we study in detail the dual approach, and propose four main contributions to it: (i) We enumerate all the possible transitions that dual methods must be able to handle, showing that prior schemes do not natively cover all of them; (ii) We show that schemes are internally asymmetric, therefore not only their construction is ambiguous, but different implementative choices lead to hexahedral meshes with different singular structure; (iii) We explore the combinatorial space of dual schemes, selecting the minimum set that covers all the possible configurations and also yields the simplest singular structure in the output hexmesh; (iv) We enlarge the class of adaptive grids that can be transformed into pure hexahedral meshes, relaxing one of the tight topological requirements imposed by previous approaches. Our extensive experiments show that our transition schemes consistently outperform prior art in terms of ability to converge to a valid solution, amount and distribution of singular mesh edges, and element count. Last but not least, we publicly release our code and reveal a conspicuous amount of technical details that were overlooked in previous literature, lowering an entry barrier that was hard to overcome for practitioners in the field.

Modelling inter-firm competitive rivalry in a port logistics cluster: a case study of Melbourne, Australia

PurposeThe paper models the effect of spatial clustering on various dimensions of inter-firm competitive rivalry among port logistics firms using Porter's five forces model.Design/methodology/approachA survey-based quantitative approach is adopted to collect data from logistics firms, which are directly or indirectly dependent on the Port of Melbourne in Australia. A structural equation modelling (SEM) technique is used to examine the theorised relationships between various dimensions of inter-firm competitive rivalry and the tendency of spatial clustering of logistics firms in the vicinity of Port of Melbourne.FindingsThe results indicate that the inter-firm competitive rivalry increases significantly when logistics firms are spatially clustered. This effect is further augmented when they cluster around the port. Co-location of firms near the port tends to increase “bargaining power of buyers”, whilst indirectly affecting “competitive rivalry” via “threats of substitutes”. This indicates that co-location enhances the bargaining power of buyers through the greater availability of substitute services that in turn promotes competitive rivalry among firms. However, co-location has an insignificant effect on “barriers to entry” and “bargaining power of suppliers”. Low entry barrier thus favours high competitive rivalry among firms. Hence, this paper validates the Porter's cluster and five forces models that confirm the positive effect of port logistics clusters (PLCs) on bargaining power of buyers and indirect effect on competitive rivalry partially mediated through threats of substitutes.Practical implicationsThis study provides empirically grounded evidence for firms to evaluate co-location decision choices and help buyers and sellers to devise business strategies to enhance inter-firm competitive rivalry and bargaining power.Originality/valueThis is the first systematic attempt to empirically validate Porter's five forces model in the context of PLC. Furthermore, the conceptualisation of PLC concept both as spatial and functional constructs (i.e. dependency on port) is novel. This study thus has broadened the meaning of cluster from a geographic entity to a more useful functional construct to reflect inter-firm dependencies.

Understanding traceability: its relevance in the adoption of quality and safety measures across the supply chain

The article is based on a previous case study of a certified papaya producer from Colima which currently implements traceability in its operations. Traceability can be defined as an instrument to respond and avoid risks in the supply chain of a product. For Small and Medium Enterprises (SMEs) the use of traceability can be a competitive advantage, adding value to their products; or either an entry barrier to access to new international markets. The article analyzes the importance of traceability and the adoption of new practices to respond to future market requirements in a competitive globalized environment.

REDUCTION OF THE ENTRY BARRIER AND THE PRESENCE OF THE “AGAINST ALL” COLUMN AS INDICATORS OF DEMOCRATIC ELECTIONS IN MODERN RUSSIA

В статье рассматривается избирательная система при использовании проходного барьера и графы «против всех» на выборах депутатов Государственной Думы. Дается оценка влияния данной графы на результаты волеизъявления граждан, рассматривается применения процентного проходного барьера, делается вывод о необходимости дальнейшего совершенствования избирательного процесса с целью наиболее широкого представительства политических сил.

MTBalance

Mountain Biking (MTB) is an increasingly popular outdoors activity which offers a unqiue connection to nature along with the health benefits of cardiovascular exercise. Yet, complex MTB technique is an entry barrier that often prevent novices from enjoying the sport. Developing interactive systems, which can support developing MTB proficiency can augment the outdoor experience and make the sport available to a larger group of users. To that end, we designed, implemented and evaluate MTBalance - a system which provides body posture feedback for beginner mountain bikers. Based on inertial tracking, MTBalance informs the user about how to correct their posture to improve MTB performance. We conducted a study in which we compared different feedback modalities for MTBalance. We observed that the system increased perceived balance awareness. Our work provides insights for designing body awareness systems for outdoor sports.

Biodiversity Knowledge Graphs: Time to move up a gear!

Harnessing worldwide biodiversity data requires integrating myriad pieces of information, often sparse and incomplete, into a global, coherent data space. To do so, projects like the Global Biodiversity Information Facility, Catalog of Life and Encyclopedia of Life have set up platforms that gather, consolidate, and centralize billions of records from multiple data sources. This approach lowers the entry barrier for scientists willing to consume aggregated biodiversity data but tends to build silos that hamper cross-platform interoperability. The Web of Data embodies a different approach underpinned by the Linked Open Data (LOD) principles (Heath and Bizer 2011). These principles bring about the building of a large, distributed, cross-domain knowledge graph (KG), wherein data description relies on vocabularies with shared, formal, machine-processable semantics. So far however, little biodiversity data have been published this way. Early efforts focused primarily on taxonomic registers, such as NCBI, VTO and AGROVOC. More recent efforts have started paving the way for the publication of more diverse biodiversity KGs (Page 2019, Penev et al. 2019, Michel et al. 2017). Today, we believe that it is time for more biodiversity data producers to join in and start publishing connected KGs spanning a much broader set of domains, far beyond just taxonomic registers. In this talk, we wish to present an on-going endeavor in line with this vision. In a previous work, we published TAXREF-LD (Michel et al. 2017), a LOD representation of the French taxonomic register developed and maintained by the French National Museum of Natural History. We modeled nomenclatural information as a thesaurus of scientific names, taxonomic information as an ontology of classes denoting taxa, and additional information such as ranks and vernacular names. Recently, we have extended the scope of TAXREF-LD to represent and interlink data as various as geographic locations, species interactions, development stages, trophic levels, as well as conservation, biogeographic, and legal status (regulations, protections, etc.). We put a specific effort into working out a model that accurately accounts for the semantics of the data while respecting knowledge engineering practices. For instance, a common design shortcoming is to attach all information as properties of a taxon. This is a rightful choice for some properties like a scientific name or conservation status, but properties that actually pertain to biological individuals themselves, e.g. habitat and trophic level, should better be attched to class members. With the presentation of this work, we wish to advance the discussion about integration scenarios based on knowledge graphs with the different biodiversity data stakeholders.

Conformation of HIV-1 Envelope governs rhesus CD4 usage and simian-human immunodeficiency virus replication

Infection of rhesus macaques with simian-human immunodeficiency viruses (SHIVs) is the preferred model system for vaccine development because SHIVs encode HIV-1 envelope glycoproteins (Env) – a key target of HIV-1 neutralizing antibodies. Since the goal of vaccines is to prevent new infections, SHIVs encoding circulating HIV-1 Env are desired as challenge viruses. Development of such biologically relevant SHIVs has been challenging as they fail to infect rhesus macaques, mainly because most circulating HIV-1 Env do not use rhesus CD4 (rhCD4) receptor for viral entry. Most primary HIV-1 Env exist in a closed conformation and occasionally transit to downstream, open conformation through an obligate intermediate conformation. Here, we provide genetic evidence that open Env conformations can overcome the rhCD4 entry barrier and increase replication of SHIVs in rhesus lymphocytes. Consistent with prior studies, we found that circulating HIV-1 Env do not use rhCD4 efficiently for viral entry. However, using HIV-1 Env with single amino acid substitutions that alter their conformational state, we found that transitions to intermediate and open Env conformation allow usage of physiological levels of rhCD4 for viral entry. We engineered these single amino acid substitutions in the transmitted/founder HIV-1BG505 Env encoded by SHIV-BG505 and found that open Env conformation enhances SHIV replication in rhesus lymphocytes. Lastly, CD4-mediated SHIV pull-down, sensitivity to soluble CD4, and fusogenicity assays indicated that open Env conformation promotes efficient rhCD4 binding and viral-host membrane fusion. These findings identify conformational state of HIV-1 Env as a major determinant for rhCD4 usage, viral fusion, and SHIV replication.

Millisecond mix-and-quench crystallography (MMQX) enables time-resolved studies of PEPCK with remote data collection

Time-resolved crystallography of biomolecules in action has advanced rapidly as methods for serial crystallography have improved, but the large number of crystals and the complex experimental infrastructure that are required remain serious obstacles to its widespread application. Here, millisecond mix-and-quench crystallography (MMQX) has been developed, which yields millisecond time-resolved data using far fewer crystals and routine remote synchrotron data collection. To demonstrate the capabilities of MMQX, the conversion of oxaloacetic acid to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase (PEPCK) is observed with a time resolution of 40 ms. By lowering the entry barrier to time-resolved crystallography, MMQX should enable a broad expansion in structural studies of protein dynamics.

On the Potential of Augmented Reality for Mathematics Teaching with the Application cleARmaths

Learning content in mathematics, such as vector geometry, is still predominantly taught in an abstract manner, as the visualization and interaction of three-dimensional problems are limited with classical forms of teaching such as blackboard lessons or exercise sheets. This research article proposes the use of augmented reality (AR) in mathematics education. The proposed approach aims at easing the learning process related to vector geometry currently taught in senior mathematics classes by using intuitive visualization. The article introduces the concept of AR and presents the didactic foundations and the influence on the learning process based on an extensive literature review. Although studies see great potential in the use of AR for teaching mathematics, the method has so far hardly been used in schools. This can be mainly explained by the technological entry barrier of AR and the lack of simple, robust AR applications, in particular for vector geometry. To fill this gap, the authors developed “cleARmaths”, a developed android application for augmented reality-based teaching in vector geometry that allows widespread use. As a didactical concept, some example exercises sessions with the app are proposed, demonstrating how the app could be used in a mathematics classroom. Finally, the app was evaluated in a mathematics class and the results analyzed in a detailed study. It was found by the teacher and students to be beneficial and amusing, demonstrating the potential for AR in mathematics classes.

Holistic Requirements Analysis for Specifying New Systems for 3D Media Production and Promotion

This paper presents a requirements engineering process for driving the design of new systems that will allow for enhancing 3D media productivity, for lowering the entry barrier in 3D media creation, and for innovative media forms across many media types. This work has been carried out with the perspective of enhancing recovery and transformation as the pandemic has driven many professionals in culture to zero income. Toward this goal, we perform a requirements engineering process based on the IEEE 830 standard for requirements specification. It allows us to elucidate system requirements through existing (AS-IS) and envisioned (TO-BE) scenarios affected by the latest trends on design methodologies and content promotion in social media. A total of 30 tools for content creation, promotion, and monetization are reviewed and 10 TO-BE scenarios were engineered and validated. The validation was performed through a survey of 24 statements on a 5 Likert scale by 47 individuals from the domains of Media, Fine arts, Architecture, and Informatics. Useful evaluation results and comments have been collected that can be useful for future systems design.