Changes in a construction project schedule can impact the project's planned duration, resulting in penalties. A manual trial-and-error probabilistic approach is usually conducted to find an appropriate set of corrective measures to mitigate delays of the overall project. However, this approach does not capture the actual goal-oriented behavior of project managers who react to the actual scenarios causing delays, leading to a fundamental modeling error. Moreover, it does not employ control and automation concepts when finding the optimal mitigation strategy. To remove this modeling error and to automate the mitigation process, the Mitigation Controller (MitC) software is developed. The MitC searches for the most cost-effective set of mitigation measures considering risk events and durations uncertainties of activities. Moreover, the MitC captures activity correlations and enables contractual penalty/reward schemes in the simulation. As a result, it returns the most effective mitigation strategy that minimizes the mitigation cost and penalty and maximizes the reward potential. The Mitigation Controller introduced here constitutes an open-source code written in Matlab

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The microtubule cytoskeleton is an intracellular polymer network involved in cell shape, cell motility, and cell division. Microtubules are self-assembling, dynamic polymers composed of tubulin proteins that alternate between phases of growth and shrinkage, a behaviour known as “dynamic instability”. A key feature of microtubules is their ability to generate pushing and pulling forces through controlled assembly and disassembly, guiding for example cell division. The stability of microtubules is largely governed by the progressive hydrolysis of incorporated tubulin dimers. In this thesis we sought to resolve microtubule assembly under force in the presence of regulatory proteins. Through the in vitro reconstitution of microtubule growth against novel micro-fabricated barriers, we studied the biochemical changes leading up to microtubule destabilization. We found that the resulting microtubule lifetimes can be understood with a simple phenomenological 1D model based on noisy microtubule growth and a single hydrolysis rate. Additionally, we explored the implementation of light-inducible protein-protein interactions to gain spatiotemporal control over microtubule function in particular and over in vitro reconstitutions in general. As a proof-of-principle, we developed a light-inducible microtubule gliding assay based on the reversible recruitment of motor proteins to a surface.@en

Force generation by molecular motors drives biological processes such as asymmetric cell division and cell migration. Microtubule gliding assays in which surface-immobilized motor proteins drive microtubule propulsion are widely used to study basic motor properties as well as the collective behavior of active self-organized systems. Additionally, these assays can be employed for nanotechnological applications such as analyte detection, biocomputation, and mechanical sensing. While such assays allow tight control over the experimental conditions, spatiotemporal control of force generation has remained underdeveloped. Here we use light-inducible protein-protein interactions to recruit molecular motors to the surface to control microtubule gliding activity in vitro. We show that using these light-inducible interactions, proteins can be recruited to the surface in patterns, reaching a â5-fold enrichment within 6 s upon illumination. Subsequently, proteins are released with a half-life of 13 s when the illumination is stopped. We furthermore demonstrate that light-controlled kinesin recruitment results in reversible activation of microtubule gliding along the surface, enabling efficient control over local microtubule motility. Our approach to locally control force generation offers a way to study the effects of nonuniform pulling forces on different microtubule arrays and also provides novel strategies for local control in nanotechnological applications.

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The dynamic instability of microtubules plays a key role in controlling their organization and function, but the cellular mechanisms regulating this process are poorly understood. Here, we show that cytoplasmic linker-associated proteins (CLASPs) suppress transitions from microtubule growth to shortening, termed catastrophes, including those induced by microtubule-destabilizing agents and physical barriers. Mammalian CLASPs encompass three TOG-like domains, TOG1, TOG2, and TOG3, none of which bind to free tubulin. TOG2 is essential for catastrophe suppression, whereas TOG3 mildly enhances rescues but cannot suppress catastrophes. These functions are inhibited by the C-terminal domain of CLASP2, while the TOG1 domain can release this auto-inhibition. TOG2 fused to a positively charged microtubule-binding peptide autonomously accumulates at growing but not shrinking ends, suppresses catastrophes, and stimulates rescues. CLASPs suppress catastrophes by stabilizing growing microtubule ends, including incomplete ones, preventing their depolymerization and promoting their recovery into complete tubes. TOG2 domain is the key determinant of these activities.

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Microtubules switch between growing and shrinking states, a feature known as dynamic instability. The biochemical parameters underlying dynamic instability are modulated by a wide variety of microtubule-associated proteins that enable the strict control of microtubule dynamics in cells. The forces generated by controlled growth and shrinkage of microtubules drive a large range of processes, including organelle positioning, mitotic spindle assembly, and chromosome segregation. In the past decade, our understanding of microtubule dynamics and microtubule force generation has progressed significantly. Here, we review the microtubule-intrinsic process of dynamic instability, the effect of external factors on this process, and how the resulting forces act on various biological systems. Recently, reconstitution-based approaches have strongly benefited from extensive biochemical and biophysical characterization of individual components that are involved in regulating or transmitting microtubule-driven forces. We will focus on the current state of reconstituting increasingly complex biological systems and provide new directions for future developments.

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