Pasch trades on the projective triple system of order 31

We determine all 120 nonisomorphic systems obtainable from the projective Steiner triple system of order 31 by at most three Pasch trades. Exactly three of these, each corresponding to three Pasch trades, are rigid. Thus three Pasch trades suffice, and are required, in order to convert the projective system of order 31 to a rigid system. This contrasts with the projective system of order 15 where four Pasch trades are required. We also show that four Pasch trades are required in order to convert the projective system of order 63 to a rigid system

Resilient Critical Infrastructure Management using Service Oriented Architecture

Abstract—The SERSCIS project aims to support the use of interconnected systems of services in Critical Infrastructure (CI) applications. The problem of system interconnectedness is aptly demonstrated by ‘Airport Collaborative Decision Making’ (ACDM). Failure or underperformance of any of the interlinked ICT systems may compromise the ability of airports to plan their use of resources to sustain high levels of air traffic, or to provide accurate aircraft movement forecasts to the wider European air traffic management systems. The proposed solution is to introduce further SERSCIS ICT components to manage dependability and interdependency. These use semantic models of the critical infrastructure, including its ICT services, to identify faults and potential risks and to increase human awareness of them. Semantics allows information and services to be described in such a way that makes them understandable to computers. Thus when a failure (or a threat of failure) is detected, SERSCIS components can take action to manage the consequences, including changing the interdependency relationships between services. In some cases, the components will be able to take action autonomously — e.g. to manage ‘local’ issues such as the allocation of CPU time to maintain service performance, or the selection of services where there are redundant sources available. In other cases the components will alert human operators so they can take action instead. The goal of this paper is to describe a Service Oriented Architecture (SOA) that can be used to address the management of ICT components and interdependencies in critical infrastructure systems. Index Terms—resilience; QoS; SOA; critical infrastructure, SLA

Real Evidence of a Subducting Plate

The objective of this activity is to allow students to manipulate real data and understand how such data are interpreted and used in support of a theory. The concepts studied are maps, earthquakes, and plate tectonics, particularly a subduction zone plate boundary. The student will learn or be refreshed on using latitude and longitude for mapping purposes. The activity should be used in a unit on plate tectonics so that the student has a basic understanding of plate theory, boundaries, and types of crust. It is also useful to guide a class discussion about the different types of evidence used to support the theory of plate tectonics. Educational levels: High school, Undergraduate lower division

Just ticking the box: A social informatics model of the consequences of consent

Given the societal diffusion, proliferation and ubiquity of computerised systems and platforms, it is generally perceived by consumers that systems and eBusiness platforms often pose a threat to the privacy of their supplied information (Srnicek, 2017; Andreotti et al., 2018). Furthermore, as we see the replacement of systems that were once manual and paper-based migrate to digital processes and information systems (Lunt et al., 2019), consent in the information era is reduced to ‘Yes’ or ‘No’ option, often in the form of a tick box. Additionally, despite the arrival of the General Data Protection Regulation in 2018 as means to provide protection in relation to data processing, we argue that there is a lack of transparency in relation to the intention of this data processing and secondary data use for the purposes of research and marketing, for example. In light of this, we argue that there exists an increasingly difficult challenge to establish a mutual understanding of what consent actually is and what the wider permutations of it represents and comprehends. The lack of mutual understanding, in a digital world that is becoming increasingly reliant on the perceived benefits of acquiring and processing large sets of data (Kitchin, 2014; Breidbach et al., 2019) is deeply problematic. It is not only problematic for the consumer, but also to system developers, platform owners, and data processors alike. To this end, this paper presents a model, derived from action research, which positions the concept of consent within a socio-technical framing. This model approaches consent, in the context of digital platforms and eBusiness and how it comes to be represented in information systems, as a socio-technical construct of moral orders that imbues the feelings, convictions and aspirations of the consumer as they are engaged in the use of digital systems. We offer that consent is merely approached as an attribute in a data model, rather than relaying the communicative understanding of the consumer. This model introduces the areas of information processing systems and information communication systems as two differing interpretations within which digital platforms can be perceived. We offer these two distinctions as a mechanism to explain and, more importantly, explore the notion of the governance of consent and how this comes to be manifested in information systems

Current Conservation in the Covariant Quark-Diquark Model of the Nucleon

The description of baryons as fully relativistic bound states of quark and glue reduces to an effective Bethe-Salpeter equation with quark-exchange interaction when irreducible 3-quark interactions are neglected and separable 2-quark (diquark) correlations are assumed. This covariant quark-diquark model of baryons is studied with the inclusion of the quark substructure of the diquark correlations. In order to maintain electromagnetic current conservation it is then necessary to go beyond the impulse approximation. A conserved current is obtained by including the coupling of the photon to the exchanged quark and direct ``seagull'' couplings to the diquark structure. Adopting a simple dynamical model of constituent quarks and exploring various parametrisations of scalar diquark correlations, the nucleon Bethe-Salpeter equation is solved and the proton and neutron electromagnetic form factors are calculated numerically. The resulting magnetic moments are still about 50% too small, the improvements necessary to remedy this are discussed. The results obtained in this framework provide an excellent description of the electric form factors (and charge radii) of the proton, up to a photon momentum transfer of 3.5GeV^2, and the neutron.Comment: 30 Pages, LaTeX2e, revised version, minor modifiactions to the text, some phrases eliminated, some remarks adde

Inter-organisational systems: a personal history

The observations reported in this paper are based on an auto-ethnography of a participative engagement in the emergence of the globalised automation, media, information, and communications technology environment in Europe, over the last four decades. The conclusion is that, in the often disruptive and un co-ordinated coalescence of the publication and mass communication, telecommunications and information systems sectors, which has been a characteristic of the emergence of the global information economy, key aspects of centuries old learning about the nature of the roles and responsibilities associated with information and communications have been lost

Design of Urban Public Spaces: Intent vs. Reality.

This study investigated how two public spaces for sport and recreation were utilized by different user groups, and how this aligned with the initial design objectives for these spaces. Two newly built urban spaces situated in Copenhagen, Denmark, provided the context for this investigation. The System for Observing Play and Recreation in Communities (SOPARC) was used to examine the physical activity of users in these two urban spaces. The architects responsible for designing each space were interviewed to ascertain the intended target group of each space and to unravel the reasons behind the design decisions. The SOPARC observations revealed that males were more vigorously active than females when using the recreation facilities, and the observed users did not align with the intended target groups. The interviews suggested that design decisions were based on minimal interdisciplinary knowledge, and that expert knowledge was chosen randomly. These findings point to a systematic lack of evidence-based practice when designing sport and recreational facilities. This article has implications for landscape architects and urban planners; a new method must be developed to embed interdisciplinary knowledge in the planning process of future sport and recreation projects. This must be done in a systematic way to make the design process transparent