Exact treatment of linear difference equations with noncommutative coefficients

The exact solution of a Cauchy problem related to a linear second-order difference equation with constant noncommutative coefficients is reported.Comment: 7 pages, 0 figure

The Bounded Confidence Model Of Opinion Dynamics

The bounded confidence model of opinion dynamics, introduced by Deffuant et al, is a stochastic model for the evolution of continuous-valued opinions within a finite group of peers. We prove that, as time goes to infinity, the opinions evolve globally into a random set of clusters too far apart to interact, and thereafter all opinions in every cluster converge to their barycenter. We then prove a mean-field limit result, propagation of chaos: as the number of peers goes to infinity in adequately started systems and time is rescaled accordingly, the opinion processes converge to i.i.d. nonlinear Markov (or McKean-Vlasov) processes; the limit opinion processes evolves as if under the influence of opinions drawn from its own instantaneous law, which are the unique solution of a nonlinear integro-differential equation of Kac type. This implies that the (random) empirical distribution processes converges to this (deterministic) solution. We then prove that, as time goes to infinity, this solution converges to a law concentrated on isolated opinions too far apart to interact, and identify sufficient conditions for the limit not to depend on the initial condition, and to be concentrated at a single opinion. Finally, we prove that if the equation has an initial condition with a density, then its solution has a density at all times, develop a numerical scheme for the corresponding functional equation, and show numerically that bifurcations may occur.Comment: 43 pages, 7 figure

CCL19-sorted mature dendritic cells have enhanced lymph node migratory capacity and function

No abstract available

Utilising the Software Engineering Methods and Theory framework to critically evaluate software engineering practice in the South African banking industry

A research report submitted to the Faculty of Engineering and The Built Environment of the University of Witwatersrand, Johannesburg In partial fulfilment of the requirements for the Degree of Master of Science in Engineering September 2015In recent years, software has become the cornerstone of banking and new business products are directly dependant on software. The delivery cycles for new features is now related to market share. This drive to use software as a vehicle for competitive advantage has created an environment in which software development of new business systems are increasingly on the critical path of many projects. An organisation’s portfolio of software intensive projects is situated within this complexity and organisations attempt to mitigate the risks associated with these complexities by implementing software development processes and practices. A key problem facing the modern bank is how to define and build a software development process that caters for both the traditional and increasingly agile genres of software development characteristics in a consistent and manageable way. The banks attempt to address this problem through continuous methodology and process improvements. Comparing and assessing non-standardised software engineering lifecycle models without a common framework is a complex and subjective task. A standardised language is important for simplifying the task for developing new methods and practices or for analysing and documenting existing practices. The Software Engineering Methods and Theory (SEMAT) initiative has developed a standardised kernel of essential concepts, together with a language that describes the essence of software engineering. This kernel, called the Essence, has recently become an Object Management Group (OMG) standard. The Essence kernel, together with its language, can be used as the underpinning theory to analyse an existing method and help provide insights that can drive method enhancements. The research report proposes a simple, actionable analysis framework to assist organisations to assess, review and develop their software engineering methods. The core concepts of the methodology are identified and mapped to the Essence concepts. The governance model of the Essence is mapped to the governance model of the industry model and a set of practices is identified and documented in the Essence language. The mapping and resulting analysis can be used to test the validity of the Essence theory in practice and identify areas for improvement in both the method and the Essence standard. The analysis framework has been applied to an operational software development lifecycle of a large South African bank. A mapping of the Essence concepts to the governance model and method documented in the lifecycle was completed. This mapping revealed that the Essence is a valid tool and can be used to describe a method in practice. Furthermore it is useful as an analysis framework to assess the governance model that manages and measures the progress of an endeavour in the Bank. The case study and resulting analysis demonstrate that the Essence standard can be used to analyse a methodology and identify areas for improvement. The analysis also identified areas for improvement in the Essence specification

Contrastive representation learning: a framework and review

Contrastive Learning has recently received interest due to its success in self-supervised representation learning in the computer vision domain. However, the origins of Contrastive Learning date as far back as the 1990s and its development has spanned across many fields and domains including Metric Learning and natural language processing. In this paper, we provide a comprehensive literature review and we propose a general Contrastive Representation Learning framework that simplifies and unifies many different contrastive learning methods. We also provide a taxonomy for each of the components of contrastive learning in order to summarise it and distinguish it from other forms of machine learning. We then discuss the inductive biases which are present in any contrastive learning system and we analyse our framework under different views from various sub-fields of Machine Learning. Examples of how contrastive learning has been applied in computer vision, natural language processing, audio processing, and others, as well as in Reinforcement Learning are also presented. Finally, we discuss the challenges and some of the most promising future research directions ahead

The Effects of Information Literacy Instruction on Business Students’ Job Readiness

The purpose of this study is to examine college student perceptions of information literacy instruction and to what extent library instruction influences students’ attitudes in their business research during their job-readiness training through the Panthers Advanced Career Experience (PACE). The findings suggest that library instruction intervention positively influenced and increased confidence in completing the information research for their client-based consultation project

Differential T Cell Function and Fate in Lymph Node and Nonlymphoid Tissues

The functions and fate of antigen-experienced T cells isolated from lymph node or nonlymphoid tissues were analyzed in a system involving adoptive transfer of in vitro–activated T cells into mice. Activated T cells present in the lymph nodes could be stimulated by antigen to divide, produce effector cytokines, and migrate to peripheral tissues. By contrast, activated T cells that had migrated into nonlymphoid tissues (lung and airway) produced substantial effector cytokines upon antigen challenge, but were completely unable to divide or migrate back to the lymph nodes. Therefore, activated T cells can undergo clonal expansion in the lymph node, but are recruited and retained as nondividing cells in nonlymphoid tissues. These distinct regulatory events in lymph node and nonlymphoid tissues reveal simple key mechanisms for both inducing and limiting T cell immunity

Vessel noise prior to pile driving at offshore windfarm sites deters harbour porpoises from potential injury zones

Acknowledgements We thank the BOWL and MOWEL teams for facilitating fieldwork and data collection during windfarm construction and providing details of the construction programmes. We also thank the members of MFRAG for their participation in a workshop dedicated to the last section of the discussion and for their valuable advice. We finally thank the two reviewers for their constructive comments.Peer reviewe