37 research outputs found

    Problematizing fit and survival: transforming the law of requisite variety through complexity misalignment

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    The law of requisite variety is widely employed in management theorizing and is linked with core strategy themes such as contingency and fit. We reflect upon requisite variety as an archetypal borrowed concept. We contrast its premises with insights from the institutional literature and commitment literature, draw propositions that set boundaries to its applicability, and review the ramifications of what we call “complexity misalignment.” In this way we contradict foundational assumptions of the law, problematize adaptation- and survival-centric views of strategizing, and theorize the role of human agency in variously complex regimes

    Effect of Pulmonary Endarterectomy for Chronic Thromboembolic Pulmonary Hypertension on Stroke Volume Response to Exercise

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    In pulmonary hypertension, exercise is limited by an impaired right ventricular (RV) stroke volume response. We hypothesized that improvement in exercise capacity after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) is paralleled by an improved RV stroke volume response. We studied the extent of PEA-induced restoration of RV stroke volume index (SVI) response to exercise using cardiac magnetic resonance imaging (cMRI). Patients with CTEPH (n = 18) and 7 healthy volunteers were included. Cardiopulmonary exercise testing and cMRI were performed before and 1 year after PEA. For cMRI studies, pre- and post-operatively, all patients exercised at 40% of their preoperative cardiopulmonary exercise testing-assessed maximal workload. Post-PEA patients (n = 13) also exercised at 40% of their postoperative maximal workload. Control subjects exercised at 40% of their predicted maximal workload. Preoperatively, SVI (n = 18) decreased during exercise from 35.9 ± 7.4 to 33.0 ± 9.0 ml·m(2) (p = 0.023); in the control subjects, SVI increased (46.6 ± 7.6 vs 57.9 ± 11.8 ml·m(-2), p = 0.001). After PEA, the SVI response (ΔSVI) improved from -2.8 ± 4.6 to 4.0 ± 4.6 ml·m(2) (p <0.001; n = 17). On exercise at 40% of the postoperative maximal workload, SVI did not increase further and was still significantly lower compared with controls. Moreover, 4 patients retained a negative SVI response, despite (near) normalization of their pulmonary hemodynamics. The improvement in SVI response was accompanied by an increased exercise tolerance and restoration of RV remodeling. In conclusion, in CTEPH, exercise is limited by an impaired stroke volume response. PEA induces a restoration of SVI response to exercise that appears, however, incomplete and not evident in all patient

    TRUST: TRust Unguarded Service Terminals

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    Nowadays, plenty of digital services are provided to citizens by means of terminals located in public unguarded places. In order to access the desired service, users, authenticate themselves by providing their credentials through such terminals. This approach opens up&nbsp;to the problem of fraudulent devices that could be installed in place of regular terminals to capture users' confidential information. Indeed, despite the development of increasingly secure systems aiming at guaranteeing an acceptable security level, users are frequently unable to distinguish between terminals on which security measures are enforced (trusted terminals) and malicious terminals that pretend to be trusted
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