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Background and Purpose: We report the results of combined recording of hemodynamic and thromboembolic phenomena during carotid endarterectomy by means of computerized electroencephalography as well as transcranial Doppler ultrasonography. The study focuses on the additional value of transcranial Doppler to detect ischemia during surgery.Methods: Combined monitoring was performed in 130 consecutive operations, using standard anesthesiological, surgical, and neurophysiological procedures.Results: A reduction of .79o of blood flow velocities in the middle cerebral artery during cross-clamping was measured in 16 patients. In seven of these cases there were no severe electroencephalographic changes and a shunt was not used, but one of the patients developed a subcortical infarct with slight disability. In 55 patients, 75 episodes of embolization were detected by transcranial Doppler. In one of these, with massive embolization after release of the clamp, an intraoperative stroke occurred without changes on

We derive hypotheses from popular accounts of how use of social media affects our strong ties. Several authors have suggested that social media use erodes our strong ties by increasing the volume of social interactions and decreasing their depth. Using two-wave panel data representative of the Dutch population between 15 and 45 years, we examine changes in the core discussion networks (CDNs) of 5312 respondents (with 10,896 relations). Contradicting an erosion of strong ties, we found positive effects of social media use on CDN size, both cross-sectionally and longitudinally. Social media use was positively related to talking to CDN members in our cross-sectional model. Finally, we found that the CDNs of frequent social media users were more dynamic than those of less frequent users: they are more likely to both lose old and gain new ties. This suggests that Internet use is associated with more, and more dynamic, social interaction.

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HRQOL improvement after CEA is restricted to patients with occlusion of the contralateral carotid artery. Assessment of outcome of CEA should be related not only to neurological classification, but also to haemodynamic factors such as contralateral occlusion.

After carotid endarterectomy, flow redistribution, as expressed by changes in blood flow velocity values, occurs in the circle of Willis. The contribution of collateral sources is diminished, and the CO(2) reactivity increases, both of which reflect improvement of the hemodynamic condition. The most improvement occurs in patients with contralateral occlusion.

Social norms have been investigated across many disciplines for many years, but until recently, studies mainly provided indirect, implicit and correlational support for the role of social norms in driving behaviour. To understand how social norms, and in particular social norm change, can generate a large-scale behavioural change to deal with some of the most pressing challenges of our current societies, such as climate change and vaccine hesitancy, we discuss and review several recent advances in social norm research that enable a more precise underpinning of the role of social norms: how to identify their existence, how to establish their causal effect on behaviour and when norm change may pass tipping points. We advocate future research on social norms to study norm change through a mechanism-based approach that integrates experimental and computational methods in theory-driven, empirically calibrated agent-based models. As such, social norm research may move beyond unequivocal praising of social norms as the missing link between self-interested behaviour and observed cooperation or as the explanation for (the lack of) social tipping. It provides the toolkit to understand explicitly where, when and how social norms can be a solution to solve large-scale problems, but also to recognize their limits. This article is part of the theme issue 'Emergent phenomena in complex physical and socio-technical systems: from cells to societies'.

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