316 research outputs found

    A framework for understanding the factors influencing pair programming success

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    Pair programming is one of the more controversial aspects of several Agile system development methods, in particular eXtreme Programming (XP). Various studies have assessed factors that either drive the success or suggest advantages (and disadvantages) of pair programming. In this exploratory study the literature on pair programming is examined and factors distilled. These factors are then compared and contrasted with those discovered in our recent Delphi study of pair programming. Gallis et al. (2003) have proposed an initial framework aimed at providing a comprehensive identification of the major factors impacting team programming situations including pair programming. However, this study demonstrates that the framework should be extended to include an additional category of factors that relate to organizational matters. These factors will be further refined, and used to develop and empirically evaluate a conceptual model of pair programming (success)

    Radiating black hole solutions in arbitrary dimensions

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    We prove a theorem that characterizes a large family of non-static solutions to Einstein equations in NN-dimensional space-time, representing, in general, spherically symmetric Type II fluid. It is shown that the best known Vaidya-based (radiating) black hole solutions to Einstein equations, in both four dimensions (4D) and higher dimensions (HD), are particular cases from this family. The spherically symmetric static black hole solutions for Type I fluid can also be retrieved. A brief discussion on the energy conditions, singularities and horizons is provided.Comment: RevTeX 9 pages, no figure

    A Study of the Δ−\Delta^--component of the wave-function in light nuclei

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    We have measured cross sections for the (π+,π±p) (\pi^+,\pi^\pm p) reactions on 3H{\rm ^3H}, 4He{\rm ^4He}, 6Li{\rm ^6Li} and 7Li{\rm ^7Li} in quasi-free kinematics at incident pion beam energy 500 MeV. An enhancement of the (π+,π−p)(\pi^+,\pi^- p) cross section in this kinematics is observed. If this is interpreted as due to quasi-free scattering from pre-existing Δ\Delta components of the nuclear wave function, the extracted probabilities are in agreement with theoretical expectations.Comment: 3 pages, 3 figures, 1 tabl

    Integration of DFDs into a UML - based model-driven engineering approach

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    The main aim of this article is to discuss how the functional and the object-oriented views can be inter-played to represent the various modeling perspectives of embedded systems.We discuss whether the object-oriented modeling paradigm, the predominant one to develop software at the present time, is also adequate for modeling embedded software and how it can be used with the functional paradigm.More specifically, we present how the main modeling tool of the traditional structured methods, data flow diagrams, can be integrated in an object-oriented development strategy based on the unified modeling language. The rationale behind the approach is that both views are important for modeling purposes in embedded systems environments, and thus a combined and integrated model is not only useful, but also fundamental for developing complex systems. The approach was integrated in amodel-driven engineering process, where tool support for the models used was provided. In addition, model transformations have been specified and implemented to automate the process.We exemplify the approach with an IPv6 router case study.FEDER -Fundação para a CiĂȘncia e a Tecnologia(HH-02-383

    The role of self-gentrification in sustainable tourism: Indigenous entrepreneurship at Honghe Hani Rice Terraces World Heritage Site, China

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    This article examines three forms of tourism gentrification occurring within the newly inscribed (2013) Honghe Hani Rice Terraces UNESCO World Heritage Site in Yunnan, China. The indigenous Hani and Yi communities who populate this remote mountainous area, possess distinct cultural practices that have supported the rice terrace ecosystem for centuries. This article draws on interviews and non-participant observation conducted with inhabitants and newcomers to analyse the types of gentrification occurring within the site. We argue that indigenous cultural practices, and consequently rice cultivation in the area, are threatened by gentrifier-led and state-led gentrification combined with high levels of outward migration of indigenous persons. This could pose a significant threat to the sustainability of tourism at this site and may ultimately compromise the site’s World Heritage Status. In the midst of these dangers, some indigenous people are shown to be improving their socioeconomic standing – and becoming “middle class” or “gentry” – particularly through adopting entrepreneurial strategies gleaned from their encounters with outside-gentrifiers and tourists. This article proposes the concept of “self-gentrification” as a way to describe individuals who seek to improve themselves and their own community, while under threat of gentrification

    Biogeochemical silica mass balances in Lake Michigan and Lake Superior

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    Silica budgets for Lake Michigan and Lake Superior differ in several respects. Mass balance calculations for both lakes agree with previous studies in that permanent burial of biogenic silica in sediments may be only about 5% of the biogenic silica produced by diatoms. Because dissolution rates are large, good estimates of permanent burial of diatoms can not be obtained indirectly from the internal cycle of silica (silica uptake by diatoms and subsequent dissolution) but must be obtained from the sediment stratigraphy. The annual net production of biogenic silica in Lake Michigan requires 71% of the winter maximum silica reservoir which must be maintained primarily by internal cycling in this large lake whereas the comparable silica demand in Lake Superior is only 8.3%. The greater silica demand in Lake Michigan is the result of phosphorus enrichment which has increased diatom production. It is hypothesized that steady-state silica dynamics in Lake Michigan were disrupted by increased diatom production between 1955 and 1970 and that a new steady state based on silica-limited diatom production developed after 1970. Mass balance calculations for Lake Michigan show in contrast with previous work that the hypothesized water column silica depletion of 3.0 g · m −3 could have occurred even though 90% or more of the biogenic silica production is recycled.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42471/1/10533_2004_Article_BF02187199.pd

    Contribuição ao estudo da interrelação flĂșor-manganĂȘs em ratos

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    Devido a numerosas discrepĂąncias nos resultados de estudos experimentais relativos Ă  interação flĂșor-manganĂȘs, propusemo-nos a verificar se a adição de manganĂȘs 5 ĂĄgua fluoretada (1 ppm), em diferentes proporçÔes fluor-manganĂȘs, levaria a uma diferente fixaçao do halogĂȘnio. Para tanto, 24 ratos Wistar, recĂ©m-desmamados, foram mantidos em dieta padrĂŁo de caseĂ­na a 27%, recebendo na sua ĂĄgua de consumo: 1) H2O destilada (controle); 2) 1,0 ppm de flĂșor: 3) 1,0 ppm de flĂșor + 0,5 ppm de manganĂȘs (F:Mn = 2,0); 4) 1,0 ppm de flĂșor +1,0 ppm de manganĂȘs (F: Mn = 1,0). Foram anotados o peso ganho e o consumo de alimento e ĂĄgua, durante os 60 dias de experimento, apĂłs o qual as patas traseiras, dos animais sacrificados, foram autoclavadas e desossadas, e os femures retirados. Posteriormente, foram estes submetidos Ă  secagem, extração da gordura, pulverização e analise do flĂșor fixado. TambĂ©m foram efetuadas analises da composição centesimal da ração e de flĂșor e manganĂȘs nesta e nas diferentes ĂĄguas de consumo. Os resultados de percentagem do flĂșor ingerido fixado nos femures, foram analisados estatisticamente pelo teste nĂŁo-paramĂ©trico de Kruskal-Wallis (nĂ­veis de 1% e 5%) mostrando que, para as proporçÔes consideradas, o flĂșor na taxa de 1 ppm, o manganĂȘs, quando administrado apĂłs o desmame, parece nĂŁo afetar a fixaçao do flĂșor. Contudo, faz-se necessĂĄrio dar continuidade aos estudos com novas proporçÔes e taxas mais elevadas de flĂșor e manganĂȘs.An experiment to determine the effects of varying the manganese concentration of the diet on the fluorine retention in the femur of rats was made. Four groups of weaning rats were fed ad libitum a 27% casein synthetic diet and were provided with water as follows: 1) distilled (control); 2) containing 1 ppm of fluorine (F); 3) 1,0 ppm F + 0,5 ppm Mn; 4) 1 ppm F + 1 ppm Mn. The weight gain and food and water consumption were measured during 60 days. The results indicated that manganese does not seem to affect the proportional fixation of fluorine in the femur. The authors think that more data should be available before a definite conclusion on the influence of the ratio F:Mn on the fluorine retention could be drawn
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