11,896 research outputs found
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 organisationâs 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 Studentsâ Job Readiness
The purpose of this study is to examine college student perceptions of information literacy instruction and to what extent library instruction influences studentsâ 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 vitroâactivated 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
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