We Don't Need Another Hero? The Impact of "Heroes" on Software Development

A software project has "Hero Developers" when 80% of contributions are delivered by 20% of the developers. Are such heroes a good idea? Are too many heroes bad for software quality? Is it better to have more/less heroes for different kinds of projects? To answer these questions, we studied 661 open source projects from Public open source software (OSS) Github and 171 projects from an Enterprise Github. We find that hero projects are very common. In fact, as projects grow in size, nearly all project become hero projects. These findings motivated us to look more closely at the effects of heroes on software development. Analysis shows that the frequency to close issues and bugs are not significantly affected by the presence of project type (Public or Enterprise). Similarly, the time needed to resolve an issue/bug/enhancement is not affected by heroes or project type. This is a surprising result since, before looking at the data, we expected that increasing heroes on a project will slow down howfast that project reacts to change. However, we do find a statistically significant association between heroes, project types, and enhancement resolution rates. Heroes do not affect enhancement resolution rates in Public projects. However, in Enterprise projects, the more heroes increase the rate at which project complete enhancements. In summary, our empirical results call for a revision of a long-held truism in software engineering. Software heroes are far more common and valuable than suggested by the literature, particularly for medium to large Enterprise developments. Organizations should reflect on better ways to find and retain more of these heroesComment: 8 pages + 1 references, Accepted to International conference on Software Engineering - Software Engineering in Practice, 201

Potentiometric and spectroscopic study of copper(II) and nickel(II) complexes of trans-dioxopentaaza macrocycles in aqueous solution

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Characteristics and outcome of ambulatory heart failure patients receiving a left ventricular assist device

International audienceAims: Despite regularly updated guidelines, there is still a delay in referral of advanced heart failure patients to mechanical circulatory support and transplant centres. We aimed to analyse characteristics and outcome of non-inotrope-dependent patients implanted with a left ventricular assist device (LVAD).Methods and results: The ASSIST-ICD registry collected LVAD data in 19 centres in France between February 2006 and December 2016. We used data of patients in Interagency Registry for Mechanically Assisted Circulatory Support Classes 4-7. The primary endpoint was survival analysis. Predictors of mortality were searched with multivariable analyses. A total of 303 patients (mean age 61.0 ± 9.9 years, male sex 86.8%) were included in the present analysis. Ischaemic cardiomyopathy was the leading heart failure aetiology (64%), and bridge to transplantation was the main implantation strategy (56.1%). The overall likelihood of being alive while on LVAD support or having a transplant at 1, 2, 3, and 5 years was 66%, 61.7%, 58.7%, and 55.1%, respectively. Age [hazard ratio (HR) 1.03, 95% confidence interval (CI) 1.00-1.05; P = 0.02], a concomitant procedure (HR 2.32, 95% CI 1.52-3.53; P < 0.0001), and temporary mechanical right ventricular support during LVAD implantation (HR 2.94, 95% CI 1.49-5.77; P = 0.002) were the only independent variables associated with mortality. Heart failure medications before or after LVAD implantation were not associated with survival.Conclusion: Ambulatory heart failure patients displayed unsatisfactory survival rates after LVAD implantation. A better selection of patients who can benefit from LVAD may help improving outcomes