Medium-induced gluon radiation and colour decoherence beyond the soft approximation

We derive the in-medium gluon radiation spectrum off a quark within the path integral formalism at finite energies, including all next-to-eikonal corrections in the propagators of quarks and gluons. Results are computed for finite formation times, including interference with vacuum amplitudes. By rewriting the medium averages in a convenient manner we present the spectrum in terms of dipole cross sections and a colour decoherence parameter with the same physical origin as that found in previous studies of the antenna radiation. This factorisation allows us to present a simple physical picture of the mediuminduced radiation for any value of the formation time, that is of interest for a probabilistic implementation of the modified parton shower. Known results are recovered for the particular cases of soft radiation and eikonal quark and for the case of a very long medium, with length much larger than the average formation times for medium-induced radiation. Technical details of the computation of the relevant n-point functions in colour space and of the required path integrals in transverse space are provided. The final result completes the calculation of all finite energy corrections for the radiation off a quark in a QCD medium that exist in the small angle approximation and for a recoilless mediumS

Valores e tensões na política cultural ibérica: um estudo de casos

Este artigo centra-se nos principais contributos do projeto europeu Uncharted sobre os valores emergentes na administração cultural europeia, apoiando-se numa vasta análise documental, em grupos focais e entrevistas a uma plêiade de atores. Analisando quatro estudos de caso ibéricos, procura-se identificar a diversidade de valores que moldam as decisões e práticas de política cultural, com foco nas tensões e conflitos entre os atores envolvidos e as suas valorações. Demonstrar-se-á que os atores se mobilizam em torno de disputas sobre a hierarquia de valores, o que exige uma compreensão dos contextos em que cada reportório se estabelece, ainda que a conflitualidade se exerça dentro de um mesmo modelo de política cultural, prevalecente nos dois países ibéricos.This article focuses on the main contributions of the European project Uncharted on emerging values in European cultural governance, relying on a wide document analysis, focus groups and interviews with a plethora of actors. By analyzing four Iberian case studies we seek to identify the diversity of values that shape cultural policy decisions and practices, focusing on the tensions and conflicts between the actors involved and their valuations. It will be shown that actors mobilize around disputes over the hierarchy of values, which requires an understanding of the contexts in which each repertoire is established, even if the conflictuality is exercised within the same model of cultural policy, prevalent in the two Iberian countries

Valores y tensiones en la política cultural ibérica: un estudio de casos

[Resumo]: Este artigo centra-se nos principais contributos do projeto europeu Uncharted sobre os valores emergentes na administração cultural europeia, apoiando-se numa vasta análise documental, em grupos focais e entrevistas a uma plêiade de atores. Analisando quatro estudos de caso ibéricos, procura-se identificar a diversidade de valores que moldam as decisões e práticas de política cultural, com foco nas tensões e conflitos entre os atores envolvidos e as suas valorações. Demonstrar-se-á que os atores se mobilizam em torno de disputas sobre a hierarquia de valores, o que exige uma compreensão dos contextos em que cada reportório se estabelece, ainda que a conflitualidade se exerça dentro de um mesmo modelo de política cultural, prevalecente nos dois países ibéricos.[Abstract]: This article focuses on the main contributions of the European project Uncharted on emerging values in European cultural governance, relying on a wide document analysis, focus groups and interviews with a plethora of actors. By analyzing four Iberian case studies we seek to identify the diversity of values that shape cultural policy decisions and practices, focusing on the tensions and conflicts between the actors involved and their valuations. It will be shown that actors mobilize around disputes over the hierarchy of values, which requires an understanding of the contexts in which each repertoire is established, even if the conflictuality is exercised within the same model of cultural policy, prevalent in the two Iberian countries.[Résumé]: Cet article se concentre sur les principales contributions du projet européen Uncharted sur les valeurs émergentes dans la gouvernance culturelle européenne, en s’appuyant sur une large analyse documentaire, des groupes de discussion et des entretiens avec une pléthore d’acteurs. En analysant quatre études de cas ibériques, nous cherchons à identifier la diversité des valeurs qui façonnent les décisions et les pratiques de la politique culturelle, en nous concentrant sur les tensions et les conflits entre les acteurs impliqués et leurs valorisations. On montrera que les acteurs se mobilisent autour de conflits sur la hiérarchie des valeurs, ce que nécessite une compréhension des contextes dans lesquels chaque répertoire est établi, même si la conflictualité s’exerce au sein d’un même modèle de politique culturelle, prévalant dans les deux pays ibériques.[Resumen]: Este artículo se centra en las principales aportaciones del proyecto europeo Uncharted sobre los valores emergentes en la gobernanza cultural europea, basándose en un amplio análisis documental, grupos de discusión y entrevistas con una gran cantidad de actores. Mediante el análisis de cuatro estudios de caso ibéricos se pretende identificar la diversidad de valores que conforman las decisiones y prácticas de política cultural, centrándose en las tensiones y conflictos entre los actores implicados y sus valoraciones. Se demostrará que los actores se movilizan en torno a las disputas sobre la jerarquía de valores, lo que exige comprender los contextos en los que se establece cada repertorio, aunque la conflictividad se ejerza dentro del mismo modelo de política cultural, predominante en los dos países ibéricos

How do companies collaborate in open source ecosystems? An empirical study of OpenStack

OpenSourceSoftware (OSS) has come to play a critical role in the software industry. Some large ecosystems enjoy the participation of large numbers of companies, each of which has its own focus and goals. Indeed, companies that otherwise compete, may become collaborators within the OSS ecosystem they participate in. Prior research has largely focused on commercial involvement in OSS projects, but there is a scarcity of research focusing on company collaborations within OSS ecosystems. Some of these ecosystems have become critical building blocks for organizations worldwide; hence, a clear understanding of how companies collaborate within large ecosystems is essential. This paper presents the results of an empirical study of the Open Stack ecosystem, in which hundreds of companies collaborate on thousands of project repositories to deliver cloud distributions. Based on a detailed analysis, we identify clusters of collaborations, and identify four strategies that companies adopt to engage with the Open Stack ecosystem. We also find that companies may engage in intentional or passive collaborations, or may work in an isolated fashion. Further, we find that a company’s position in the collaboration network is positively associated with its productivity in Open Stack. Our study sheds light on how large OSS ecosystems work, and in particular on the patterns of collaboration within one such large ecosystem

Managing to release early, often and on time in the OpenStack software ecosystem

Abstract The dictum of “Release early, release often.” by Eric Raymond as the Linux modus operandi highlights the importance of release management in open source software development. However, there are very few empirical studies addressing release management in this context. It is already known that most open source software communities adopt either a feature-based or time-based release strategy. Both have their own advantages and disadvantages that are also context-specific. Recent research reports that many prominent open source software projects have overcome a number of recurrent problems by moving from feature-based to time-based release strategies. In this longitudinal case study, we address the release management practices of OpenStack, a large scale open source project developing cloud computing technologies. We discuss how the release management practices of OpenStack have evolved in terms of chosen strategy and timeframes with close attention to processes and tools. We discuss the number of practical and managerial issues related to release management within the context of large and complex software ecosystems. Our findings also reveal that multiple release management cycles can co-exist in large and complex software ecosystems such as OpenStack