Managing Requirements Change the Informal Way: When Saying 'No' is Not an Option

© 2016 IEEE. Software has always been considered as malleable. Changes to software requirements are inevitable during the development process. Despite many software engineering advances over several decades, requirements changes are a source of project risk, particularly when businesses and technologies are evolving rapidly. Although effectively managing requirements changes is a critical aspect of software engineering, conceptions of requirements change in the literature and approaches to their management in practice still seem rudimentary. The overall goal of this study is to better understand the process of requirements change management. We present findings from an exploratory case study of requirements change management in a globally distributed setting. In this context we noted a contrast with the traditional models of requirements change. In theory, change control policies and formal processes are considered as a natural strategy to deal with requirements changes. Yet we observed that "informal requirements changes" (InfRc) were pervasive and unavoidable. Our results reveal an equally 'natural' informal change management process that is required to handle InfRc in parallel. We present a novel model of requirements change which, we argue, better represents the phenomenon and more realistically incorporates both the informal and formal types of change

Product Design Education for Circular Economy

Design has continually developed new approaches to find the most appropriate solutions to the growing environmental and social problems. At the same time higher education courses have tried to adapt their curricula accordingly. The most recently proposed model is circular economy. It reinforces the idea of a paradigm shift to a system of closed loops where there is no waste. This article develops a state of the art on the integration of sustainability in product design in higher education and its evolution to embrace circular economy. This analysis includes identifying past experiences, which contents are addressed, what methodologies are used, what type of approach (focused or dispersed) and what are the needs for teaching staff. This paper tries to identify gaps in order to purpose better solution for circular economy integration.info:eu-repo/semantics/publishedVersio

Regulation of human CD4+ T cell differentiation

Naive CD4+ T cells differentiate into specific effector subsets—Th1, Th2, Th17, and T follicular helper (Tfh)—that provide immunity against pathogen infection. The signaling pathways involved in generating these effector cells are partially known. However, the effects of mutations underlying human primary immunodeficiencies on these processes, and how they compromise specific immune responses, remain unresolved. By studying individuals with mutations in key signaling pathways, we identified nonredundant pathways regulating human CD4+ T cell differentiation in vitro. IL12Rβ1/TYK2 and IFN-γR/STAT1 function in a feed-forward loop to induce Th1 cells, whereas IL-21/IL-21R/STAT3 signaling is required for Th17, Tfh, and IL-10–secreting cells. IL12Rβ1/TYK2 and NEMO are also required for Th17 induction. Strikingly, gain-of-function STAT1 mutations recapitulated the impact of dominant-negative STAT3 mutations on Tfh and Th17 cells, revealing a putative inhibitory effect of hypermorphic STAT1 over STAT3. These findings provide mechanistic insight into the requirements for human T cell effector function, and explain clinical manifestations of these immunodeficient conditions. Furthermore, they identify molecules that could be targeted to modulate CD4+ T cell effector function in the settings of infection, vaccination, or immune dysregulation