An introduction to Graph Data Management

A graph database is a database where the data structures for the schema and/or instances are modeled as a (labeled)(directed) graph or generalizations of it, and where querying is expressed by graph-oriented operations and type constructors. In this article we present the basic notions of graph databases, give an historical overview of its main development, and study the main current systems that implement them

Insights into SusCD-mediated glycan import by a prominent gut symbiont

In Bacteroidetes, one of the dominant phyla of the mammalian gut, active uptake of large nutrients across the outer membrane is mediated by SusCD protein complexes via a “pedal bin” transport mechanism. However, many features of SusCD function in glycan uptake remain unclear, including ligand binding, the role of the SusD lid and the size limit for substrate transport. Here we characterise the β2,6 fructo-oligosaccharide (FOS) importing SusCD from Bacteroides thetaiotaomicron (Bt1762-Bt1763) to shed light on SusCD function. Co-crystal structures reveal residues involved in glycan recognition and suggest that the large binding cavity can accommodate several substrate molecules, each up to ~2.5 kDa in size, a finding supported by native mass spectrometry and isothermal titration calorimetry. Mutational studies in vivo provide functional insights into the key structural features of the SusCD apparatus and cryo-EM of the intact dimeric SusCD complex reveals several distinct states of the transporter, directly visualising the dynamics of the pedal bin transport mechanism

Disease: A Hitherto Unexplored Constraint on the Spread of Dogs (Canis lupus familiaris) in Pre-Columbian South America

Although debate continues, there is agreement that dogs (Canis lupus familiaris) were first domesticated in Eurasia, spreading from there to other parts of the world. However, while that expansion already extended as far as Europe, China, and North America by the early Holocene, dogs spread into (and south of) the tropics only much later. In South America, for example, the earliest well attested instances of their presence do not reach back much beyond 3000 cal. BC, and dogs were still absent from large parts of the continent – Amazonia, the Gran Chaco, and much of the Southern Cone – at European contact. Previous explanations for these patterns have focused on cultural choice, the unsuitability of dogs for hunting certain kinds of tropical forest prey, and otherwise unspecified environmental hazards, while acknowledging that Neotropical lowland forests witness high rates of canine mortality. Building on previous work in Sub-Saharan Africa (Mitchell 2015) and noting that the dog’s closest relatives, the grey wolf (C. lupus) and the coyote (C. latrans), were likewise absent from South and most of Central America in Pre- Columbian times, this paper explores instead the possibility that infectious disease constrained the spread of dogs into Neotropical environments. Four diseases are considered, all likely to be native and/or endemic to South America: canine distemper, canine trypanosomiasis, canine rangeliosis, and canine visceral leishmaniasis caused by infection with Leishmania amazonensis and L. colombiensis. The paper concludes by suggesting ways in which the hypothesis that disease constrained the expansion of dogs into South America can be developed further

GOAL : a graph-based object and association language

A graph-based model for describing Schemes and instances of object databases together with a graphical data manipulation language based on pattern matching are introduced. The data model allows the explicit modeling of classes and relations which contain objects and associations, respectively. GOAL consists mainly of two operations, the addition and the deletion. These perform on every part. of the instance where a certain pattern is found. We will present. the syntax and the semantics of the language, and show its computational Completeness

Mobile Constraints For Semantic Web Applications

We present a framework for semantic web applications based on constraint interchange and processing. At the core of the framework is a well-established semantic data model (P/FDM) with an associated expressive constraint language (Colan). To allow data instances to be transported across a network, we map our data model to the RDF Schema specification. To allow constraints to be transported, we define a Constraint Interchange Format (CIF) in the form of an RDF Schema for Colan, allowing each constraint to be defined as a resource in its own right. We show that, because Colan is essentially a syntacticallysugared form of first-order logic, and P/FDM is based on the widelyused extended ER model, our CIF is actually very widely applicable and reusable. Finally, we outline a set of services for constraint fusion and solving, which are particularly applicable to business-to-business e-commerce applications. These services are accessible using the CIF

Functional querying in graph databases

Abstract The paper is focused on a functional querying in graph databases. We consider labelled property graph model and mention also the graph model behind XML databases. An attention is devoted to functional modelling of graph databases both at a conceptual and data level. The notions of graph conceptual schema and graph database schema are considered. The notion of a typed attribute is used as a basic structure both on the conceptual and database level. As a formal approach to declarative graph database querying a version of typed lambda calculus is used. This approach allows to use a logic necessary for querying, arithmetic as well as aggregation function. Another advantage is the ability to deal with relations and graphs in one integrated environment

Space Picture - Ein interaktives Hypermediasystem für die Archivierung und das Retrieval von hochaufgelösten Satellitenbildern

Das Papier beschreibt Space-Picture, ein System für die Archivierung, die Organisation und den Zugriff auf große Mengen von hochaufgelösten Satellitenbildern. Es verwendet Hyperlinks für die Strukturierung der Daten und bietet ein leicht bedienbares, graphisch-interaktives User-Interface. Space-Picture wurde auf der Basis von Hyper-Picture entwickelt, einem Toolkit für die einfache Realisierung von Hypermedia-Anwendungen