Validation, comparison, and combination of algorithms for automatic detection of pulmonary nodules in computed tomography images: The LUNA16 challenge

Automatic detection of pulmonary nodules in thoracic computed tomography (CT) scans has been an active area of research for the last two decades. However, there have only been few studies that provide a comparative performance evaluation of different systems on a common database. We have therefore set up the LUNA16 challenge, an objective evaluation framework for automatic nodule detection algorithms using the largest publicly available reference database of chest CT scans, the LIDC-IDRI data set. In LUNA16, participants develop their algorithm and upload their predictions on 888 CT scans in one of the two tracks: 1) the complete nodule detection track where a complete CAD system should be developed, or 2) the false positive reduction track where a provided set of nodule candidates should be classified. This paper describes the setup of LUNA16 and presents the results of the challenge so far. Moreover, the impact of combining individual systems on the detection performance was also investigated. It was observed that the leading solutions employed convolutional networks and used the provided set of nodule candidates. The combination of these solutions achieved an excellent sensitivity of over 95% at fewer than 1.0 false positives per scan. This highlights the potential of combining algorithms to improve the detection performance. Our observer study with four expert readers has shown that the best system detects nodules that were missed by expert readers who originally annotated the LIDC-IDRI data. We released this set of additional nodules for further development of CAD systems

Managing Impressions in the Face of Rising Stakeholder Pressures: Examining Oil Companies' Shifting Stances in the Climate Change Debate

International audienceIn this paper, we examine how organizations’ impression management (IM) evolves in response to rising stakeholder pressures regarding organizations’ corporate responsibility initiatives. We conducted a comparative case study analysis over a period of 13 years (1997–2009) for two organizations—Exxon and BP—that took extreme (but different) initial stances on climate change. We found that as stakeholder pressures rose, their IM tactics unfolded in four phases: (i) advocating the initial stance, (ii) sensegiving to clarify the initial stance, (iii) image repairing, and (iv) adjusting the stance. Taken together, our analysis of IM over these four phases provides three key insights about the evolution of IM in the face of rising pressures. First, when faced with stakeholder pressures, it seems that organizations do not immediately resort to conforming but tend to give in gradually when pressures increase and start to come from relatively powerful stakeholders. Second, evolution of IM seems to be characterized by path dependence, i.e., even as organizations’ positions evolve, they continue to show their conviction in their initial positions and try to convey that their subsequent positions flow logically from the previous ones. Finally, IM involves navigation between symbolism and substance, and companies tend to strive toward harmonizing their symbolic and substantive actions as stakeholder pressure increases

Corporate Twitter Channels: The Impact of Engagement and Informedness on Corporate Reputation

We examine communication via a corporate Twitter channel and its effects on corporate reputation. We identify the importance of user engagement and informedness in explaining corporate reputation and examine three design factors that likely affect user engagement in a corporate Twitter channel. We conduct an exploratory 2 x 2 x 2 experiment among Twitter users to collect data. We find that the depth of the relationship among users, the level of corporate involvement, and the purpose of the channel interactively influence user engagement. Our findings suggest that deeper relationships among users of a corporate Twitter channel lead to higher user engagement when the level of corporate involvement with the channel is high and when the channel has a specific purpose, but not when the level of corporate involvement is high and the channel has a generic purpose. Surprisingly, when the channel has a generic purpose, a high degree of corporate involvement actually decreases user engagement. This finding implies that, under certain circumstances, a lower degree of corporate involvement in a social media channel may be more desirable. We also find that channel credibility positively influences user informedness. This is the first study that examines the dynamics of communication through a corporate Twitter channel. It contributes to the previous research related to social media by identifying engagement and informedness as two major factors that influence firms' reputation. Our research can help marketing and social media managers to decide on channel design aspects, such as whether to require users to register with an identity or to allow anonymous participation, whether to allocate dedicated employees to respond to user requests, and whether to set up different channels for different purposes