A multi-scale sub-voxel perfusion model to estimate diffusive capillary wall conductivity in multiple sclerosis lesions from perfusion MRI data.

We propose a new mathematical model to learn capillary leakage coefficients from dynamic susceptibility contrast MRI data. To this end, we derive an embedded mixed-dimension flow and transport model for brain tissue perfusion on a sub-voxel scale. This model is used to obtain the contrast agent concentration distribution in a single MRI voxel during a perfusion MRI sequence. We further present a magnetic resonance signal model for the considered sequence including a model for local susceptibility effects. This allows modeling MR signal-time curves that can be compared to clinical MRI data. The proposed model can be used as a forward model in the inverse modeling problem of inferring model parameters such as the diffusive capillary wall conductivity. Acute multiple sclerosis lesions are associated with a breach in the integrity of the blood brain barrier. Applying the model to perfusion MR data of a patient with acute multiple sclerosis lesions, we conclude that diffusive capillary wall conductivity is a good indicator for characterizing activity of lesions, even if other patient-specific model parameters are not well-known. This article is protected by copyright. All rights reserved

The incongruity of misfit: A systematic literature review and research agenda

For decades, research on person-environment (P-E) fit has been a prevalent topic, emphasizing alignment between employees and the work environment and the accompanying positive consequences that flow from good fit. However, given the frequency of change and volatility experienced in organizations, it is far more likely that individuals, work groups, and organizations will sporadically experience misfit with various aspects of the environment. This recognition has led to steady growth in misfit research, but this literature lacks conceptual clarity, provides differing views on the interplay between fit and misfit, and as a result, insights on the consequences of misfit are fragmented. To address these shortcomings, we conduct a systematic review the misfit literature, analyzing 106 scholarly articles published between 1981 and 2021. Our review is guided by the following questions: (1) What is misfit and how is it measured? (2) How does it develop, grow, and change over time, and (3) What are its antecedents and outcomes? Our review offers three key contributions. First, we identify four distinct conceptualizations of misfit from the literature and then offer an integrative definition of misfit as the recognition of misalignment with one or more aspects of the environment experienced in moments, as events occur, or as situations evolve. Second, we provide a multilevel synthesis of the antecedents and outcomes of misfit that highlights the need for more cross-level and multilevel research. Third, we lay out a rich and detailed agenda of future research to further enhance our knowledge of misfit as a concept distinct from its P-E fit roots

Coupling DuMuX and DUNE-PDELab to investigate evaporation at the interface between Darcy and Navier-Stokes flow

An implementation of a coupled Navier-Stokes/Darcy model based on different Dune discretization modules is presented. The Darcy model is taken from DuMuX, the Navier-Stokes model is implemented on top of Dune-PDELab, and the coupling is done with help of Dune-MultiDomain together with some project-specific auxiliary code. The Navier-Stokes model features one fluid phase, the Darcy model two fluid phases. Each fluid phase may be composed of two components, in addition, non-isothermal processes are considered. The coupling between free and porous-medium flow uses a sharp interface between both subdomains and conserves mass, momentum, and energy by accounting for the corresponding fluxes across the interface. A cell-centered finite volume method (FVM) is combined with a marker and cell (MAC) scheme. It solves the coupled problem in one monolithic system using a Newton method and a direct linear solver. Numerical results demonstrate the basic functioning and a lab-scale reference application

Under positive pressure: how stakeholder pressure affects corporate social responsibility implementation

This study tests a model that links stakeholder pressure to the implementation of corporate social responsibility (CSR) activities and market performance. Stakeholder groups and competitors might exert pressure on companies to implement CSR, which could lead to positive effects on market performance. Using structural equation modeling (SEM), the authors find that stakeholders and competitors exert pressure differently. The effect of CSR implementation on market performance is moderated by market dynamism: It affects market performance more in dynamic environments. The authors discuss implications for both companies and stakeholders