Introdução: A esclerodermia é rara doença do tecido conectivo que se manifesta através da esclerose cutânea e variável acometimento sistêmico. Duas categorias de esclerodermia são conhecidas: esclerose sistêmica, caracterizada por esclerose cutânea e acometimento visceral e a esclerodermia localizada ou morfeia que classicamente apresenta evolução benigna e autolimitada, confinada a pele e/ou tecidos subjacentes. Estudos recentes demonstram que a forma localizada possa eventualmente apresentar acometimento de órgãos internos e morbidade variável. Objetivo: Neste estudo objetivamos determinar as características demográficas, a prevalência de manifestações sistêmicas e alterações laboratoriais, bem como a associação com doenças autoimunes, em pacientes com esclerodermia da face. Métodos: Pacientes com esclerodermia localizada, incluindo os casos de esclerodermia em golpe de sabre, síndrome de Parry-Romberg e morfeia em placas com acometimento facial, foram avaliados e submetidos à investigação neurológica, incluindo exame clínico neurológico e ressonância magnética de crânio, e avaliação oftalmológica. Após 3 anos, o subgrupo de pacientes disponível para seguimento foi ressubmetido à ressonância magnética. Resultados: Foram estudados 34 pacientes com esclerodermia localizada da face. Deste total, 64,7% apresentavam uma ou mais manifestações extracutâneas, sendo cefaleia a queixa mais frequente, encontrada em 61,8% dos pacientes. Dos 23 pacientes submetidos à avaliação neurológica, 56,5% apresentaram alterações neurológicas possivelmente associadas à esclerodermia. Alterações à ressonância magnética foram observadas em 50% dos casos. O achado mais frequente foi a presença de lesões parenquimatosas com alteração de sinal em 50% dos pacientes. Dos pacientes que apresentavam alteração neurológica, 80% também apresentavam alguma alteração à ressonância magnética. Doze pacientes foram ressubmetidos a novo exame após 3 anos. Em todos os pacientes os achados de imagem se mantiveram inalterados. Durante esse intervalo de 3 anos, 25% dos pacientes apresentaram sinais de atividade da esclerodermia. Quanto à avaliação oftalmológica, 67,9% dos pacientes avaliados apresentaram alteração, sendo os achados mais frequentes a ocorrência de alterações orbiculares da esclerodermia (20,6%) e xeroftalmia (10,7%). Conclusão: Pacientes com esclerodermia localizada da face apresentam alta prevalência de alterações neurológicas e oftalmológicas. Baseado nestes achados, sugerimos que todos os casos de esclerodermia localizada da face devam ser detalhadamente examinados quanto à presença de alterações sistêmicas / Introduction: Scleroderma is a rare connective tissue disease that manifests as skin sclerosis and variable systemic involvement. Two categories of scleroderma are known: systemic sclerosis, characterized by cutaneous sclerosis and visceral involvement and localized scleroderma or morphea which classically presents benign evolution and selflimited, confined to the skin and / or underlying tissue. Recent studies show that the localized form may possibly course with involvement of internal organs and variable morbidity. Objective: This study aimed to determine the demographic characteristics, the prevalence of systemic manifestations and laboratory findings, as well as the association with autoimmune diseases, in patients with scleroderma of the face. Methods: Patients with localized scleroderma, including cases of scleroderma en coup de sabre, Parry-Romberg syndrome and morphea plaque with facial involvement were evaluated and underwent neurological examination, including neurologic examination and magnetic resonance imaging, and ophthalmology evaluation. After 3 years, the subgroup of patients available for follow-up was subjected again to MRI. Results: We studied 34 patients with localized scleroderma of the face. Of this total, 64,7% had one or more extracutaneous manifestation, headache being the most frequent complaint found in 61,8% of patients. Of the 23 patients undergoing neurological evaluation, 56,5% had neurological changes possibly associated with scleroderma. MRI changes were observed in 50% of cases. The most frequent was the presence of parenchymal lesions with signal alteration in 50% of patients. Of the patients who had neurological deficits, 80% also had a change to MRI. Twelve patients were subjected again to another MRI scan after 3 years. In all patients, imaging findings were unchanged. During this interval of 3 years, 25% of patients showed signs of activity of scleroderma. As for ophthalmologic evaluation, 67,9% of patients showed abnormalities, with the most frequent findings being the occurrence of orbicular changes of scleroderma (20.6%) and xerophthalmia (10.7%). Conclusion: Patients with localized scleroderma face have a high prevalence of neurological and ophthalmological changes. Based on these findings, we suggest that all cases of localized scleroderma of the face should be thoroughly examined for the presence of systemic changes

Introdução: A esclerodermia é rara doença do tecido conectivo que se manifesta através da esclerose cutânea e variável acometimento sistêmico. Duas categorias de esclerodermia são conhecidas: esclerose sistêmica, caracterizada por esclerose cutânea e acometimento visceral e a esclerodermia localizada ou morfeia que classicamente apresenta evolução benigna e autolimitada, confinada a pele e/ou tecidos subjacentes. Estudos recentes demonstram que a forma localizada possa eventualmente apresentar acometimento de órgãos internos e morbidade variável. Objetivo: Neste estudo objetivamos determinar as características demográficas, a prevalência de manifestações sistêmicas e alterações laboratoriais, bem como a associação com doenças autoimunes, em pacientes com esclerodermia da face. Métodos: Pacientes com esclerodermia localizada, incluindo os casos de esclerodermia em golpe de sabre, síndrome de Parry-Romberg e morfeia em placas com acometimento facial, foram avaliados e submetidos à investigação neurológica, incluindo exame clínico neurológico e ressonância magnética de crânio, e avaliação oftalmológica. Após 3 anos, o subgrupo de pacientes disponível para seguimento foi ressubmetido à ressonância magnética. Resultados: Foram estudados 34 pacientes com esclerodermia localizada da face. Deste total, 64,7% apresentavam uma ou mais manifestações extracutâneas, sendo cefaleia a queixa mais frequente, encontrada em 61,8% dos pacientes. Dos 23 pacientes submetidos à avaliação neurológica, 56,5% apresentaram alterações neurológicas possivelmente associadas à esclerodermia. Alterações à ressonância magnética foram observadas em 50% dos casos. O achado mais frequente foi a presença de lesões parenquimatosas com alteração de sinal em 50% dos pacientes. Dos pacientes que apresentavam alteração neurológica, 80% também apresentavam alguma alteração à ressonância magnética. Doze pacientes foram ressubmetidos a novo exame após 3 anos. Em todos os pacientes os achados de imagem se mantiveram inalterados. Durante esse intervalo de 3 anos, 25% dos pacientes apresentaram sinais de atividade da esclerodermia. Quanto à avaliação oftalmológica, 67,9% dos pacientes avaliados apresentaram alteração, sendo os achados mais frequentes a ocorrência de alterações orbiculares da esclerodermia (20,6%) e xeroftalmia (10,7%). Conclusão: Pacientes com esclerodermia localizada da face apresentam alta prevalência de alterações neurológicas e oftalmológicas. Baseado nestes achados, sugerimos que todos os casos de esclerodermia localizada da face devam ser detalhadamente examinados quanto à presença de alterações sistêmicas / Introduction: Scleroderma is a rare connective tissue disease that manifests as skin sclerosis and variable systemic involvement. Two categories of scleroderma are known: systemic sclerosis, characterized by cutaneous sclerosis and visceral involvement and localized scleroderma or morphea which classically presents benign evolution and selflimited, confined to the skin and / or underlying tissue. Recent studies show that the localized form may possibly course with involvement of internal organs and variable morbidity. Objective: This study aimed to determine the demographic characteristics, the prevalence of systemic manifestations and laboratory findings, as well as the association with autoimmune diseases, in patients with scleroderma of the face. Methods: Patients with localized scleroderma, including cases of scleroderma en coup de sabre, Parry-Romberg syndrome and morphea plaque with facial involvement were evaluated and underwent neurological examination, including neurologic examination and magnetic resonance imaging, and ophthalmology evaluation. After 3 years, the subgroup of patients available for follow-up was subjected again to MRI. Results: We studied 34 patients with localized scleroderma of the face. Of this total, 64,7% had one or more extracutaneous manifestation, headache being the most frequent complaint found in 61,8% of patients. Of the 23 patients undergoing neurological evaluation, 56,5% had neurological changes possibly associated with scleroderma. MRI changes were observed in 50% of cases. The most frequent was the presence of parenchymal lesions with signal alteration in 50% of patients. Of the patients who had neurological deficits, 80% also had a change to MRI. Twelve patients were subjected again to another MRI scan after 3 years. In all patients, imaging findings were unchanged. During this interval of 3 years, 25% of patients showed signs of activity of scleroderma. As for ophthalmologic evaluation, 67,9% of patients showed abnormalities, with the most frequent findings being the occurrence of orbicular changes of scleroderma (20.6%) and xerophthalmia (10.7%). Conclusion: Patients with localized scleroderma face have a high prevalence of neurological and ophthalmological changes. Based on these findings, we suggest that all cases of localized scleroderma of the face should be thoroughly examined for the presence of systemic changes

This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. The two boundary layer flows are studied through spectral element simulations and eigenvalue computations, which enable their long-term behavior as well as the mechanisms causing transition to be determined. The emergence of transition in these cases is found to originate from a linear flow instability, but whereas the onset of this instability in the Blasius flow can be associated with a localized region in the vicinity of the suction orifice, the instability in the Falkner–Skan–Cooke flow involves the entire flow field. Due to this difference, the results of the eigenvalue analysis in the former case are found to be robust with respect to numerical parameters and domain size, whereas the results in the latter case exhibit an extreme sensitivity that prevents domain independent critical parameters from being determined. The instability of the two helices is primarily addressed through experiments and analytic theory. It is shown that the well known pairing instability of neighboring vortex filaments is responsible for transition, and careful measurements enable growth rates of the instabilities to be obtained that are in close agreement with theoretical predictions. Using the experimental baseflow data, a successful attempt is subsequently also made to reproduce this experiment numerically. In the second part of the thesis, a novel method for computing the optimal forcing of a dynamical system is developed. The method is based on an application of the inverse power method preconditioned by the Laplace preconditioner to the direct and adjoint resolvent operators. The method is analyzed for the Ginzburg–Landau equation and afterwards the Navier–Stokes equations, where it is implemented in the spectral element method and validated on the two-dimensional lid-driven cavity flow and the flow around a cylinder. / <p>QC 20171124</p>

Over the past decade, the explosive growth of the Internet has led to a surge of interest to understand and predict aggregate behavior of large number of people or agents, particularly when they are connected through an underlying network structure. Numerous Internet-based applications have emerged that are as diverse as getting micro-tasks executed through online labor markets (also known as crowd sourcing) to acquiring new skills through massively open online courses (also known as MOOCs). However, there has been a major inadequacy in existing studies with respect to evaluating the impact of strategic behavior of the agents participating in such networks, crowds, and classrooms. The primary focus of this doctoral work is to understand the equilibrium behaviour emerging from these real-world, strategic environments by blending ideas from the areas of game theory, graph theory, and optimization, to derive novel solutions to these new-age economic models. In particular, we investigate the following three research challenges: (1) How do strategic agents form connections with one another? Will it ever happen that strategically stable networks are social welfare maximizing as well? (2) How do we design mechanisms for eliciting truthful feedback about an object (perhaps a new product or service or person) from a crowd of strategic raters? What can we tell about these mechanisms when the raters are connected through a social network? (3) How do we incentivize better participation of instructors and students in online edu-cation forums? Can we recommend optimal strategies to students and instructors to get the best out of these forums?

The electronic structure of the zero-gap two-dimensional graphene has a charge neutrality point exactly at the Fermi level that limits the practical application of this material. There are several ways to modify the Fermi-level-region of graphene, e.g. adsorption of graphene on different substrates or different molecules on its surface. In all cases the so-called dispersion or van der Waals interactions can play a crucial role in the mechanism, which describes the modification of electronic structure of graphene. The adsorption of water on graphene is not very accurately reproduced in the standard density functional theory (DFT) calculations and highly-accurate quantum-chemical treatments are required. A possibility to apply wavefunction-based methods to extended systems is the use of local correlation schemes. The adsorption energies obtained in the present work by means of CCSD(T) are much higher in magnitude than the values calculated with standard DFT functional although they agree that physisorption is observed. The obtained results are compared with the values available in the literature for binding of water on the graphene-like substrates. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

The size and conformational complexity of proteins and other large systems represent major challenges for today's methods of quantum chemistry.This thesis is centered around the development of new computational tools to gain molecular-level insight into electronic transitions in such systems. To meet this challenge, we focus on the polarizable embedding (PE) model, which takes advantage of the fact that many electronic transitions are localized to a smaller part of the entire system.This motivates a partitioning of the large system into two regions that are treated at different levels of theory:The smaller part directly involved in the electronic process is described using accurate quantum-chemical methods, while the effects of the rest of the system, the environment, are incorporated into the Hamiltonian of the quantum region in an effective manner. This thesis presents extensions of the PE model with theaim of expanding its range of applicability to describe electronic transitions in large molecular systemsin the optical and X-ray regions. The developments cover both improvements with regardto the quantum region as well as the embedding potential representing the environment.Regarding the former, a damped linear response formulation has been implemented to allow for calculations of absorption spectra of large molecular systems acrossthe entire frequency range. A special feature of this development is its abilityto address core excitations that are otherwise not easily accessible.Another important development presented in this thesis is the coupling of the PE model to a multi-configuration self-consistent-field description of the quantum region and its further combination with response theory. In essence, this extends the PE model to the study of electronic transitions in large systems that are prone to static correlation --- a situation that is frequently encountered in biological systems. In addition to the direct environmental effects on the electronic structure of the quantum region, another important component of the description of electronic transitions in large molecular systems is an accurate account of the indirect effects of the environment, i.e., the geometrical distortions in the quantum region imposed by the environment. In thisthesis we have taken the first step toward the inclusion of geometry distortions in the PE frameworkby formulating and implementing molecular gradients for the quantum region. To identify critical points related to the environment description, we perform a theoretical analysis of the PE model starting from a full quantum-mechanicaltreatment of a composite system. Based on this, we present strategies for an accurate yet efficient construction of the embedding potentialcovering both the calculation of ground state and transition properties. The accurate representation of the environment makes it possible to reduce the size of the quantum region without compromising the overall accuracy of the final results. This further enables use of highly accurate quantum-chemical methods despite their unfavorable scaling with the size of the system. Finally, some examples of applications will be presented to demonstrate how the PE model may be applied as a tool to gain insight into and rationalize the factors influencing electronic transitions in large molecular systems of increasing complexity. / <p>The dissertation was awarded the best PhD thesis prize 2016 by the Danish Academy of Natural Sciences.</p><p></p><p>QC 20170209</p>

Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optique. / This thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing.

Malgré leurs contribution dans plusieurs domaines, les biopuces à lecture plasmonique conventionnelles basées sur l'utilisation d’un film métallique plan d'or, sont limitées en terme de sensibilité surtout quand il s'agit de détecter des molécules de faible masse molaire à l’état de trace.Dans ce cadre, nous étudions numériquement et expérimentalement le potentiel de détection d’interactions biomoléculaires d’une nouvelle génération de biopuces à lecture plasmonique intégrant un film métallique micro-nano-structurée en réseau rectangulaire 1D. L’étude numérique développée met en œuvre une méthode hybride, basée sur la combinaison de deux méthodes classiques : la méthode des éléments finis et la méthode modale de Fourier. Grâce à ce nouvel outil numérique, nous présentons une cartographie exhaustive du potentiel de détection d’une couche biologique, en variant les paramètres de la structuration liés aux dimensions du réseau. La réponse de la biopuce à l’accrochage de biomolécules est ensuite interprétée théoriquement par les différents phénomènes plasmoniques notamment les «points chauds» et les bandes plasmoniques interdites. Nos calculs soulignent l'importance de l’exploitation du confinement de la lumière à travers la structuration sub-longueur d’onde des surfaces plasmoniques. Ceci permet non seulement d’optimiser les paramètres géométriques afin d’améliorer la sensibilité vis-à-vis de la réponse d’une biopuce conventionnelle, mais aussi de mettre en évidence la transition entre le régime où les plasmons propagatifs dominent et le régime où les plasmons localisés dominent. De nouvelles figures de mérite sont introduites pour évaluer les performances des biopuces structurées.Cette étude montre également que de nouvelles opportunités pour améliorer davantage la bio-sensibilité sont offertes, si la localisation de biomolécules peut être effectuée dans les régions où le champ électrique est amplifié et confiné. / Surface plasmons resonance imaging with continuous thin metallic films have become a central tool for the study of biomolecular interactions. However, in order to extend the field of applications of surface plasmons resonance systems to the trace detection of biomolecules having low molecular weight, a change in the plasmonic sensing methodology is needed. In this study, we investigate theoretically and experimentally the sensing potential of 2D nano- and micro- ribbon grating structuration on the surface of Kretschmann-based surface plasmon resonance biosensors when they are used for detection of biomolecular binding events. Numerical simulations were carried out by employing a fast and novel model based on the hybridization of two classical methods, the Fourier Modal Method and the Finite Element Method. Our calculations confirm the importance of light manipulation by means of structuration of the plasmonic thin film surfaces on the nano- and micro- scales. Not only does it highlight the geometric parameters that allow the sensitivity enhancement, and associated figures of merit, compared with the response of the conventional surface plasmon resonance biosensor based on a flat surface, but it also describes the transition from the regime where the propagating surface plasmon mode dominates to the regime where the localized surface plasmon mode dominates. An exhaustive mapping of the biosensing potential of the nano- and micro- structured biosensors surface is presented, varying the structural parameters related to the ribbon grating dimensions. New figures of merit are introduced to evaluate the performance of the structured biosensors. The structuration also leads to the creation of regions on biosensor chips that are characterized by strongly enhanced electromagnetic fields. New opportunities for further improving the bio-sensitivity are offered if localization of biomolecules can be carried out in these regions of high electromagnetic fields enhancement and confined.

Systeme mit Zeitverzögerung sind von großem Interesse in Nichtlinearer Dynamik und allgegenwärtig in den Naturwissenschaften. Gegenstand dieser Doktorarbeit ist die raumzeitliche Dynamik räumlich-ausgedehnter, nichtlinearer Systeme mit Zeitverzögerung, mit besonderem Augenmerk auf deren lokalisierte Lösungen. Die betrachteten Systeme werden beschrieben durch partielle Differentialgleichungen und gekoppelte Systeme von gewöhnlichen Differentialgleichungen mit verzögerter Rückkopplung. Hinsichtlich der partiellen Differentialgleichungen untersucht diese Arbeit die Existenz und Stabilität der ebenen Wellenlösungen ebenso, wie die Existenz und Stabilität der lokalisierten Lösungen der eindimensionalen, komplexen, kubischen und kubisch-quintischen Ginzburg-Landau Gleichung mit verzögerter, optischer Rückkopplung. Das erste Ergebnis dieser Arbeit ist die vollständige Beschreibung der Menge der ebenen Wellenlösungen und ihre Stabilität für lange Verzögerungszeiten. Aufgrund der Symmetrie der Ginzburg-Landau Gleichung bildet diese Menge eine eindimensionale Familie, die zum Auftreten einer „Tube“ in Parameter-Koordinaten führt. Das zweite, neuartige Ergebnis ist die Beschreibung der Modulationsinstabilität dieser lokalisierten Strukturen. Diese Instabilität kann zu einer periodischen und chaotischen Zickzackbewegung der Lösung führen. Das dritte Resultat ist die Charakterisierung gebundener Impulsfolgen in einem System von gekoppelten gewöhnlichen Differentialgleichungen mit Zeitverzögerung, das zur Beschreibung einer Anordnung von modengekoppelten Lasers herangezogen wird. In diesem Regime interagieren die modengekoppelten Impulse in verschiedenen Lasern lokal über die Balance von Abstoßung und Anziehung. Resultierend daraus entstehen Cluster von Impulsen, die in einzelnen modengekoppelten Lasern nicht möglich sind. Sämtliche genannte Phänomene wurden analytisch und numerisch behandelt. / Systems with time-delay are ubiquitous in nature and attract significant interest in the field of nonlinear dynamics. The scope of this Thesis is the spatiotemporal dynamics in spatially extended nonlinear systems with time-delay, with a focus on the dynamics of localized structures. The systems under consideration are described by partial differential equations with delayed feedback and coupled systems of delay differential equations. For the partial differential equations, the existence and stability of plane wave solutions as well as localized structures are investigated in one-dimensional complex cubic and cubic-quintic Ginzburg-Landau equation with delayed feedback. The first result of this Thesis is the complete description of the set of plane wave solutions and their stability in the limit of large delay time. Due to the symmetry of Ginzburg-Landau equation, this set forms a one-dimensional family which leads to the appearance of the “tube” in parameter coordinates which is filled densely with plane wave solutions with the increase of the delay time. The second novel result is the description of modulational instability of localized structures in spatially extended systems with time-delay which can lead to periodic and chaotic zigzagging movement of the solution. The third result is the description of bound pulse trains in coupled delay systems depicting an array of mode-locked lasers. In this regime mode-locked pulses in different lasers interact locally via the balance of their repulsion and attraction. As a result, clusters of pulses emerge which can not exist in a solitary mode-locked laser. All of the aforementioned phenomena were described analytically and the results are supported by path continuation methods as well as direct numerical simulations with a specially designed software tool.

L’objectif de ce sujet de thèse est de prédire l’apparition des instabilités plastiques (striction diffuse et striction localisée) dans les matériaux métalliques. Ces matériaux sont décrits par des modèles de comportement élasto-plastique couplés à l’endommagement. L'approche de Lemaitre, reliant l'endommagement à la déformation plastique équivalente et au taux de restitution de la densité d'énergie élastique, est adoptée. Parmi les différents critères et indicateurs qui sont considérés pour la prédiction des instabilités matériau, la théorie de bifurcation et les critères de type force maximum sont tout particulièrement analysés et comparés. Un objectif important de cette étude consiste à déterminer les mécanismes déstabilisants clés associés à cette modélisation du comportement, ainsi que l’impact des différents aspects physiques et des paramètres matériau sur l’apparition de la striction. Les développements résultants sont appliqués à une sélection représentative de matériaux métalliques afin prédire leurs limites de formabilités. Cette approche combinant des lois de comportement et critères de striction peut être utilisée comme outil théorique et numérique d’aide à la conception de nouveaux matériaux à ductilité améliorée / The aim of the present work is to predict the occurrence of plastic instabilities (diffuse and localized necking) in thin sheet metals. The prediction of these plastic instabilities is undertaken using an elastic–plastic model coupled with ductile damage, which is then combined with various plastic instability criteria theory. The bifurcation-based criteria and the maximum force criterion used in this work are formulated within a general three-dimensional modeling framework, and then applied for the particular case of plane-stress conditions for sheet metals. Some theoretical relationships or links between the different investigated necking criteria are established, which allows a hierarchical classification in terms of their conservative character in predicting critical necking strains. The resulting numerical tool is implemented into the finite element code ABAQUS/Standard to predict forming limit diagrams, in both situations of a fully three-dimensional formulation and a plane-stress framework. This approach, that combines constitutive equations to necking criteria, serves as a useful tool in the design of new materials with improved ductility