Yes / In recent years, there has been significant attention given to stakeholder management, which involves the intricate interaction between organisations and individuals, as well as diverse groups that can significantly affect or shape an organisation's decisions. While progress has been made, African countries are seen as the next promising frontier for progress and advancement. Nevertheless, there remains a lack of understanding of this concept, as the continent is undergoing remarkable economic growth. Entrepreneurs operating in such environments face intricate landscapes when it comes to stakeholder management. Consequently, understanding how stakeholders contribute to the growth of entrepreneurial ventures in Africa is crucial to promote sustainable and responsible business practices. This chapter presents insights that can stimulate future research on stakeholder management within the intricate and diverse African setting. The chapter conceptualises the relationship between stakeholders and entrepreneurship in Africa and shows how entrepreneurial firms navigate the challenges associated with weak institutional environments. / The full-text of this book chapter will be released for public view at the end of the publisher embargo on 7 Jun 2025.

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Cette thèse est consacrée à l’étude du système de Boussinesq stationnaire:-νΔu+(u⋅∇)u+∇π=θg, div u=0,dans Ω(1a)-κΔθ+u⋅∇θ=h,dans Ω (1b)où Ω⊂R^3 est un ouvert, borné et connexe; les inconnues du système sont u,π et θ: la vitesse, la pression et la température du fluide, respectivement; ν>0 est la viscosité cinématique du fluide, κ>0 est la diffusivité thermique du fluide, g est l’accélération de la pesanteur et h est une source de chaleur appliquée au fluide.L’objectif de cette thèse est l’étude de la théorie L^p pour le système de Boussinesq en considérant deux différents types de conditions aux limites du champ de vitesse. En effet, dans une première partie, nous considérons une condition de Dirichlet non homogèneu=u_b, sur Γ (2)où Γ désigne la frontière du domaine. Dans une deuxième partie, nous considérons une condition de Navier non homogèneu⋅n=0,2[D(u)n]_τ+αu_τ=a,sur Γ(3)où D(u)=1/2 (∇u+(∇u)^T ) est le tenseur de déformation associé au champ de vitesse u, n est le vecteur normal unitaire extérieur, τ est le correspondant vecteur tangent unitaire, α et a sont une fonction scalaire de friction et un champ de vecteur tangentiel donnés sur la frontière, respectivement. De plus, la condition aux limites pour la température sera, dans les deux premières parties, une condition aux limites de Dirichlet non homogèneθ=θ_b, sur Γ. (4)Alors, premièrement, nous étudions l’existence et l’unicité d’une solution faible pour le problème (1), (2) et (4) dans le cas hilbertien. Également, l’existence de solutions généralisées pour p≥3/2 et des solutions fortes pour 1<p<∞ est démontrée. De plus, l’existence et l’unicité de la solution très faible sont étudiées. Il est intéressant de noter que puisque une condition de Dirichlet non homogène est considérée pour le champ de vitesse, le fait que la frontière du domaine pourrait être non-connexe joue un rôle fondamental puisque cela apparait de manière explicite dans les hypothèses des principaux résultats.D’autre part, dans la deuxième partie, nous étudions l’existence de solutions faibles dans le cas hilbertien, ainsi que l’existence de solutions généralisées pour p>2 et des solutions fortes pour p≥6/5 pour le problème (1), (3) et (4). Notez que l’hypothèse d’une frontière non-connexe, mentionnée précédemment, ne figurait pas dans cette partie du travail en raison de la restriction d’imperméabilité de la frontière.Enfin, dans la dernière partie de cette thèse, nous étudions la théorie L^p pour les équations de Stokes avec la condition de Navier (3). Plus précisément, nous examinons la régularité W^(1,p) pour p≥2 et la régularité W^(2,p) pour p≥6/5.Mots clés: système de Boussinesq; régularité L^p; solutions faibles; solutions fortes; solutions très faibles / This thesis is dedicated to the study of the stationary Boussinesq system:-νΔu+(u⋅∇)u+∇π=θg, div u=0,in Ω(1a)-κΔθ+u⋅∇θ=h,in Ω (1b)where Ω⊂R^3 is an open bounded connected set; u,π and θ are the velocity field, pressure and temperature of the fluid, respectively, and stand for the unknowns of the system; ν>0 is the kinematic viscosity of the fluid, κ>0 is the thermal diffusivity of the fluid, g is the gravitational acceleration and h is a heat source applied to the fluid.The aim of this thesis is the study of the L^p-theory for the stationary Boussinesq system in the context of two different types of boundary conditions for the velocity field. Indeed, in the first part of the thesis, we will consider a non-homogeneous Dirichlet boundary conditionu=u_b, on Γ (2)where Γ denotes the boundary of the domain; meanwhile in the second part, the velocity field will be prescribed through a non-homogeneous Navier boundary conditionu⋅n=0,2[D(u)n]_τ+αu_τ=a,on Γ(3)where D(u)=1/2 (∇u+(∇u)^T ) is the strain tensor associated with the velocity field u, n is the unit outward normal vector, τ is the corresponding unit tangent vector, α and a are a friction scalar function and a tangential vector field defined both on the boundary, respectively. Further, the boundary condition for the temperature will be, in the first two parts of the thesis, a non-homogeneous Dirichlet boundary conditionθ=θ_b, on Γ. (4)Then, firstly, we study the existence and uniqueness of the weak solution for the problem (1), (2) and (4) in the hilbertian case. Also, the existence of generalized solutions for p≥3/2 and strong solutions for 1<p<∞ is showed. Furthermore, the existence and uniqueness of the very weak solution is studied. It is worth to note that because a non-homogeneous Dirichlet boundary condition is considered for the velocity field, the fact that the boundary of the domain could be non-connected plays a fundamental role since it appears in an explicit way in the assumptions of some of the main results.In the second part, we study the existence of weak solutions in the hilbertian case, as well as the existence of generalized solutions for p>2 and strong solutions for p≥6/5 for the problem (1), (3) and (4). Note that the assumption of a non-connected boundary, which was mentioned before, will not appear here due to the impermeability restriction on the boundary.Finally, in the last part of this thesis, we study the L^p-theory for the Stokes equations with Navier boundary condition (3). Specifically, we deal with the W^(1,p)-regularity for p≥2 and the W^(2,p)-regularity for p≥6/5.Keywords: Boussinesq system; L^p-regularity; weak solutions; strong solutions; very weak solutions

We consider the eigenvalue problem associated to the 1-Laplace operator. We define higher eigensolutions by means of weak slope and establish existence of a sequence of eigensolutions by using nonsmooth critical point theory. In addition, we deduce a new necessary condition for the first eigenvalue of the 1-Laplace operator by means of inner variations. / Wir betrachten das zum 1-Laplace-Operator gehörige Eigenwertproblem. Wir definieren höhere Eigenlösungen mittels weak slope und weisen die Existenz einer Folge von Eigenlösungen nach, indem wir die nichtglatte Theorie kritischer Punkte anwenden. Zusätzlich leiten wir eine neue notwendige Bedingung für den ersten Eigenwert des 1-Laplace-Operators mittels innerer Variationen her.

The goal of the Q-weak experiment is to make a measurement of the proton's weak charge ($Q^p_W = 1-4\sin^2\theta_W$) to an accuracy of ~4%. This would represent a ~0.3% determination of the weak mixing angle ($\sin^2\theta_W$) at low energy. The measurement may be used for a precision test of the Standard Model (SM) prediction on the running of $\sin^2\theta_W$ with energy scale. The Q-weak experiment operates at Thomas Jefferson National Accelerator Facility (Jefferson Lab). The experiment determines the proton's weak charge by measuring the parity violating asymmetry in elastic electron-proton scattering at low momentum transfer $Q^2 = 0.026 (GeV/c)^2$ and forward angles (~8 degree). The anticipated size of the asymmetry, based on the SM, is about 230 parts per billion (ppb). With the proposed accuracy, the experiment may probe new physics beyond Standard Model at the TeV scale. This thesis focuses on my contributions to the experiment, including track reconstruction for momentum transfer determination of the scattering process, and the focal plane scanner, a detector I designed and built to measure the flux profile of scattered electrons on the focal plane of the Q-weak spectrometer to assist in the extrapolation of low beam current tracking results to high beam current. Preliminary results from the commissioning and the first run period of the Q-weak experiment are reported and discussed.

The goal of the Q-weak experiment is to make a measurement of the proton's weak charge ($Q^p_W = 1-4\sin^2\theta_W$) to an accuracy of ~4%. This would represent a ~0.3% determination of the weak mixing angle ($\sin^2\theta_W$) at low energy. The measurement may be used for a precision test of the Standard Model (SM) prediction on the running of $\sin^2\theta_W$ with energy scale. The Q-weak experiment operates at Thomas Jefferson National Accelerator Facility (Jefferson Lab). The experiment determines the proton's weak charge by measuring the parity violating asymmetry in elastic electron-proton scattering at low momentum transfer $Q^2 = 0.026 (GeV/c)^2$ and forward angles (~8 degree). The anticipated size of the asymmetry, based on the SM, is about 230 parts per billion (ppb). With the proposed accuracy, the experiment may probe new physics beyond Standard Model at the TeV scale. This thesis focuses on my contributions to the experiment, including track reconstruction for momentum transfer determination of the scattering process, and the focal plane scanner, a detector I designed and built to measure the flux profile of scattered electrons on the focal plane of the Q-weak spectrometer to assist in the extrapolation of low beam current tracking results to high beam current. Preliminary results from the commissioning and the first run period of the Q-weak experiment are reported and discussed.

Osteoporosis is defined as an osteometabolic disease characterized by the reduction of bone mineral density (BMD) and micro-architectural deterioration, leading to enhanced bone fragility and increased susceptibility to fractures. Chronic inflammation affecting bone resorption and/or bone formation is an important mechanism in the hystopathology of osteoporosis. In this regard, several inflammatory markers are associated in special, tumor necrosis factor alpha (TNFα). Recent evidence from the literature pointed out that other members of the TNF superfamily, the tumor necrosis factor TNF-like weak inducer of apoptosis (TWEAK), in its soluble bioactive form (sTWEAK), has been related with diverse endocrine metabolic disarrangements such as diabetes mellitus or metabolic syndrome. Thus, we hypothesized a possible association between sTWEAK plasma levels and bone fractures and diabetes mellitus in post menopausal women. This was a cross sectional study nested in a cohort of 1057 post menopausal women outpatients attending the UBS, Unidades Básicas de Saúde, of Santa Maria. We used data from 52 individuals recruited who reported major bone fractures. For the control group, we aleatory recruited 110 individuals without the history of major bone fractures. All subjects in this study proceeded to a standard questionnaire about clinical data and were submitted to anthropometry evaluation. Blood samples were obtained for the biochemical profile consisting in fast glucose, total cholesterol, TG, HDL, LDL, creatinine, albumin, calcium and phosphorus in serum. sTWEAK concentration was established by ELISA. Assimetric variables were logN transformed. Student T test or Mann-Whitney test were used to comparison of data between two groups. For statistical analysis that form more than two groups were employed ANOVA or Chi quadrate and Fisher s test. An statistical significant reduction (p=0.002) of sTWEAK (log transformed) was observed in diabetes mellitus (DM) subjects in comparison to non-diabetics. There was no differences in the plasma levels of sTWEAK when the history of major bone fractures was analysed. Even when stratified for DM and fractures, Ln sTWEAK remained consistently reduced in the group of individuals with DM without fractures against non-diabetics no-fractures women (p <0.01). Findings from this study indicated that plasma levels of sTWEAK was not related with bone fragility in post menopausal women population. Nevertheless, low plasma levels of this biomarker were associated with diabetes mellitus, as previously described in the literature. / A osteoporose é um transtorno osteometabólico caracterizado pela diminuição da densidade mineral óssea (DMO) e deterioração de sua microarquitetura com o consequente aumento da fragilidade do osso e suscetibilidade à fraturas. A fisiopatologia dessa doença tem a inflamação crônica como importante mecanismo no aumento da reabsorção e redução da formação óssea. Entre os marcadores inflamatórios associados à osteoporose destacam-se aqueles do grupo dos fatores de necrose tumoral, em particular, o fator de necrose tumoral alfa (TNFα). Evidências recentes da literatura observaram que um outro membro da mesma família, o TNFlike weak inducer of apoptosis (TWEAK), em sua forma solúvel (sTWEAK), foi relacionado com a presença de outros distúrbios endócrino metabólicos, tais como diabetes mellitus (DM) e síndrome metabólica. Com base nisso, testamos a hipótese de associação entre sTWEAK e fraturas ósseas maiores, e também DM, em mulheres na pós menopausa. Este é um estudo transversal que partiu de uma coorte de 1057 pacientes na pós menopausa que consultam nas Unidades Básicas de Saúde da cidade de Santa Maria-RS. Foram recrutadas 52 pacientes com histórico de fraturas ósseas maiores e, para o grupo controle, escolhidas aleatoriamente 110 pacientes sem história de fraturas ósseas. Todos os indivíduos do estudo responderam a um questionário padronizado sobre a sua história clínica além de serem submetidos a avaliação antropométrica e exames bioquímicos (glicose de jejum, colesterol total, triglicerídeos, HDL, LDL, creatinina, albumina, cálcio e fósforo). Os níveis plasmáticos de sTWEAK foram avaliados pelo método de ELISA. As variáveis com distribuição assimétrica foram submetidas à transformação para o seu logaritmo natural e então comparadas. Para a análise estatística entre dois grupos foi feita a utilização dos testes T de Student ou Mann-Whitney. Para mais de dois grupos foram empregados ANOVA ou os testes de Chi Quadrado ou Fisher. Foi observada redução significativa (p=0.002) dos valores do sTWEAK (transformado para logN) nos indivíduos com DM em comparação com os sem DM. Não houveram diferenças quando analisado somente o histórico de fraturas. Estratificando a população em subgrupos de acordo com o critério de existência de fratura reportada ou de diagnóstico de DM, permaneceu somente a diferença entre os grupos com DM sem fratura e sem DM sem fratura (p<0.01). Os achados indicam que na população de mulheres na pós menopausa com e sem história de fraturas ósseas maiores, os níveis plasmáticos de sTWEAK não tem associação com a fragilidade óssea. Entretanto, níveis baixos deste biomarcador estão associados com o diagnóstico de DM, como reportado na literatura.

We consider the eigenvalue problem associated to the 1-Laplace operator. We define higher eigensolutions by means of weak slope and establish existence of a sequence of eigensolutions by using nonsmooth critical point theory. In addition, we deduce a new necessary condition for the first eigenvalue of the 1-Laplace operator by means of inner variations. / Wir betrachten das zum 1-Laplace-Operator gehörige Eigenwertproblem. Wir definieren höhere Eigenlösungen mittels weak slope und weisen die Existenz einer Folge von Eigenlösungen nach, indem wir die nichtglatte Theorie kritischer Punkte anwenden. Zusätzlich leiten wir eine neue notwendige Bedingung für den ersten Eigenwert des 1-Laplace-Operators mittels innerer Variationen her.

L’éolien offshore est l’énergie marine la plus avancée et utilisée dans le monde. Afin d’accroître l’énergie extraite du vent, les dimensions des éoliennes deviennent plus importantes et les parcs éoliens sont installées de plus en plus loin des côtes, où les mers sont plus agitées et les vents plus forts. De fait, les opérations marines sont plus complexes et plus chères et les fenêtres météo sont écourtées et se raréfient. Dans le cadre de cette thèse, un logiciel de simulation numérique des opérations marines est développé, en particulier pour des applications de descentes et de remontées de colis lourds. L’Algorithme aux Corps Rigides Composites, implémenté dans le logiciel InWave, est utilisé pour modéliser le système multicorps. Un modèle de câble et de treuil est développé, suivant la théorie multicorps utilisée, et comparé à la théorie câble classique dite « lumped mass ». Les efforts hydrodynamiques ainsi que les interactions hydrodynamiques sont modélisés par une théorie potentiel instationnaire satisfaisant l’hypothèse de faible perturbation, dite « weak-scatterer ». L’approche « weak-scatterer » du logiciel WS_CN est étendue aux simulations multi-flotteurs et validée par comparaison avec des données expérimentales. InWave et WS_CN sont couplés afin de résoudre l’interaction houle-structure pour des systèmes multicorps articulés en mer. Un couplage fort est adopté pour sa robustesse. L’équation de couplage est établie et validée via des comparaisons avec WS_CN. Le logiciel ainsi crée se nomme InWaveS_CN et utilise un code d’intégration en Python. Une nouvelle stratégie de maillage, basée sur un algorithme de découpe de maillages et une méthode par avance de front, est développée dans WS_CN. Enfin, des essais en bassin d’une opération de redressement ont été menés à l’ECN. La comparaison entre les simulations numériques et les données expérimentales offre une première et prometteuse validation d’InWaveS_CN. / Offshore wind represents the most advanced and used marine energy in the world. To increase the wind power extraction, turbines grow in size and wind farms are installed further offshore in presence of rough seas and strong winds. Marine operations become more challenging and expensive, weather windows are shorter and less frequent. This PhD work focuses on the development of a numerical tool to simulate marine operations with consistency, in particular lowering and lifting operations. The Composite-Rigid-Body Algorithm, implemented in the numerical tool InWave, is used to model multibody systems. A cable model and a winch model are developed following this multibody approach and compared to the classical low-order lumped mass theory. Hydrodynamic loads and hydrodynamic interactions are simulated using an unsteady potential flow theory based on the weakscatterer hypothesis, implemented in the numerical tool WS_CN. This approach is extended to multibody simulations and validated with comparisons to experimental data. InWave and WS_CN are coupled to solve wavestructure interaction for articulated multibody systems with large relative motions in waves. A tight coupling is selected for its robustness. The coupling equation is derived and validated from comparisons with WS_CN. This leads to the creation of a new numerical tool, InWaveS_CN, using Python as glue code language. A new mesh strategy, based on the coupling between a panel cutting method and an advance front method, is developed in WS_CN. Experiments of an upending operation were conducted at Ecole Centrale de Nantes. The comparison between the numerical simulations and the experimental data leads to a first and promising validation of InWaveS_CN.

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