Assembling Coherent Network Topologies Using Round-Trip Graphs (short paper)

Discovering the network topology in computer networks is challenging due to limited communication and incomplete information about non-immediately connected nodes. In this paper we address the problem of assembling partial views obtained by discovery tools into a coherent representation, using round-trip graphs: labelled bipartite directed graphs representing the communications between hosts, interfaces, and networks. A merge operation is introduced, facilitating compositional and incremental assembly of partial views. This research provides a practical solution for incrementally constructing a comprehensive network topology

A Calculus for Subjective Communication

In this paper we introduce Subjective Communication, a new interaction model for CAS and generalizing the attribute-based communication introduced in the AbC calculus. In this model, a message is broadcasted to every process, but each process can view the very same message in different ways, depending on its attributes. To formalize this model, we introduce SCC, the Subjective Communication Calculus, for which we propose two semantics: Direct SCC, particularly useful when dealing with an edge computing communication paradigm, and Indirect SCC, more suited to a cloud-centric model. We then introduce a stateless bisimilarity for our semantics, which we prove to be a congruence

DBCChecker: A Bigraph-Based Tool for Checking Security Properties of Container Compositions

Despite their widespread application in modern systems, container composition is often complex and error-prone. In this work, we present DBCChecker, a tool aiming to verify security properties of systems obtained by composition of containers. From the configuration of a container-based system and an abstract description of the interface behaviour of each container, the tool builds a formal model of the overall system, which can be verified in ProVerif (an automatic symbolic protocol verifier), to check that the overall system satisfies the required properties. The system can be described in a specification language capable to express at once the interfaces and connections of containers and the relevant behavioural aspects of their interfaces, called JSON Bigraph Format (JBF), and inspired by previous formal models, based on bigraphs, for containerized architectures

Joint knowledge generation in European R&D networks: Results from a discrete choice modelling perspective

The objective of this study is to explore the determinants of joint knowledge generation within European networks of R&D collaboration. This study distinguishes between two types of joint knowledge generation: scientific and commercially relevant knowledge generation. Joint generation of scientific knowledge is measured by co-authored scientific publications, while joint commercially relevant knowledge is measured by co-owned patents and artefacts. Unit of analysis are dyads of organisations jointly participating in projects of the 5th EU Framework Programme (FP5). The data for carrying out this study is taken from a survey among FP5 participants and the EUPRO database. 23 EU member countries (Bulgaria, Cyprus, Malta and Rumania are excluded) plus Switzerland and Norway are included. Regression methods for discrete choice (logit and probit) are employed to meet the objective. The independent variables taken into consideration encompass the types of organisations involved in the dyad, geographical and cultural obstacles, relational factors and project characteristics. Results show that dyads involving universities have the highest probability not only to jointly generate scientific knowledge but also to jointly generate commercially relevant knowledge, whereas the involvement of an industry organisation results in a low probability for both types of knowledge generation. Perhaps, this can be attributed to the fact that joint knowledge generation entails disclosure of own knowledge, which is actually a task of universities but is problematic for industry organisations. Another important result is that crossing national border has a significant positive rather than negative effect on joint scientific knowledge generation, which is essentially a consequence of how the Framework Programmes had been set up. Similarly, crossing EU-15 external border has a positive effect on joint knowledge generation, indicating that the FPs work well in achieving their aim of supporting the catching up process of CEE countries. But, joint generation of commercially relevant knowledge is negatively influenced by language borders. This can be explained by the fact that the co-development of patentable knowledge or artefacts requires more intensive and complex interactions than to co-author a scientific publication where English is the lingua franca anyway. Results on relational factors and project characteristics satisfy expectations: Duration of collaboration and the existence of previous collaboration have a positive effect on joint knowledge generation, whereas the project size, measured by number of participants, affects joint knowledge generation negatively

Elucidating Surface Structure with Action Spectroscopy

Surface Action Spectroscopy, a vibrational spectroscopy method developed in recent years at the Fritz Haber Institute is employed for structure determination of clean and H2O-dosed (111) magnetite surfaces. Surface structural information is revealed by using the microscopic surface vibrations as a fingerprint of the surface structure. Such vibrations involve just the topmost atomic layers, and therefore the structural information is truly surface related. Our results strongly support the view that regular Fe3O4(111)/Pt(111) is terminated by the so-called Fetet1 termination, that the biphase termination of Fe3O4(111)/Pt(111) consists of FeO and Fe3O4(111) terminated areas, and we show that the method can differentiate between different water structures in H2O-derived adsorbate layers on Fe3O4(111)/Pt(111). With this, we conclude that the method is a capable new member in the set of techniques providing crucial information to elucidate surface structures. The method does not rely on translational symmetry and can therefore also be applied to systems which are not well ordered. Even an application to rough surfaces is possible

Accurate Hartree-Fock energy of extended systems using large Gaussian basis sets

Calculating highly accurate thermochemical properties of condensed matter via wave function-based approaches (such as e.g. Hartree-Fock or hybrid functionals) has recently attracted much interest. We here present two strategies providing accurate Hartree-Fock energies for solid LiH in a large Gaussian basis set and applying periodic boundary conditions. The total energies were obtained using two different approaches, namely a supercell evaluation of Hartree-Fock exchange using a truncated Coulomb operator and an extrapolation toward the full-range Hartree-Fock limit of a Pad\'e fit to a series of short-range screened Hartree-Fock calculations. These two techniques agreed to significant precision. We also present the Hartree-Fock cohesive energy of LiH (converged to within sub-meV) at the experimental equilibrium volume as well as the Hartree-Fock equilibrium lattice constant and bulk modulus.Comment: 7.5 pages, 2 figures, submitted to Phys. Rev. B; v2: typos removed, References adde

Barriers to cross-region research and development collaborations in Europe. Evidence from the fifth European Framework Programme

The focus of this paper is on cross-region R&D collaboration funded by the 5th EU Framework Programme (FP5). The objective is to measure distance, institutional, language and technological barrier effects that may hamper collaborative activities between European regions. Particular emphasis is laid on measuring discrepancies between two types of collaborative R&D activities, those generating output in terms of scientific publications and those that do not. The study area is composed of 255 NUTS-2 regions that cover the pre-2007 member states of the European Union (excluding Malta and Cyprus) as well as Norway and Switzerland. We employ a negative binomial spatial interaction model specification to address the research question, along with an eigenvector spatial filtering technique suggested by Fischer and Griffith (2008) to account for the presence of network autocorrelation in the origin-destination cooperation data. The study provides evidence that the role of geographic distance as collaborative deterrent is significantly lower if collaborations generate scientific output. Institutional barriers do not play a significant role for collaborations with scientific output. Language and technological barriers are smaller but the estimates indicate no significant discrepancies between the two types of collaborative R&D activities that are in focus of this study.Series: Working Papers in Regional Scienc

Resolving atomic diffusion in Ru(0001)-O(2×2) with spiral high-speed scanning tunneling microscopy

An intermediate state in atomic diffusion processes in the O(2×2) layer on Ru(0001) is resolved with spiral high-speed scanning tunneling microscopy (STM). The diffusion of atomic oxygen in the adlayer has been studied by density functional theory and STM. Transition state theory proposes a migration pathway for the diffusion in the oxygen adlayer. With spiral scan geometries—a new approach to high-speed STM—the oxygen vacancy mobility on the highly covered Ru(0001) surface is determined to be in the range of 0.1 to 1 Hz. Experimental evidence for the intermediate state along the oxygen diffusion pathway is provided in real space and real time

Dynamic instance generation for few-shot handwritten document layout segmentation (short paper)

Historical handwritten document analysis is an important activity to retrieve information about our past. Given that this type of process is slow and time-consuming, the humanities community is searching for new techniques that could aid them in this activity. Document layout analysis is a branch of machine learning that aims to extract semantic informations from digitised documents. Here we propose a new framework for handwritten document layout analysis that differentiates from the current state-of-the-art by the fact that it features few-shot learning, thus allowing for good results with little manually labelled data and the dynamic instance generation process. Our results were obtained using the DIVA - HisDB dataset

Dynamics in the O(2 × 1) adlayer on Ru(0001): bridging timescales from milliseconds to minutes by scanning tunneling microscopy

The dynamics within an O(2 × 1) adlayer on Ru(0001) is studied by density functional theory and high-speed scanning tunneling microscopy. Transition state theory proposes dynamic oxygen species in the reduced O(2 × 1) layer at room temperature. Collective diffusion processes can result in structural reorientations of characteristic stripe patterns. Spiral high-speed scanning tunneling microscopy measurements reveal this reorientation as a function of time in real space. Measurements, ranging over several minutes with constantly high frame rates of 20 Hz resolved the gradual reorientation. Moreover, reversible fast flipping events of stripe patterns are observed. These measurements relate the observations of long-term atomic rearrangements and their underlying fast processes captured within several tens of milliseconds