No description available.

No description available.

The ever increasing demand for Internet traffic, storage and processing requires an ever increasing amount of hardware resources. In addition to this, infrastructure providers over-provision system architectures to serve users at peak times without performance delays. Over-provisioning leads to underutilization and thus to unnecessary power consumption. Therefore, there is a need for workload management strategies to map and schedule different services simultaneously in an energy-efficient manner without compromising performance, specially for heterogeneous micro-server architectures. This requires statistical models of how services interfere with each other, thereby affecting both performance and energy consumption. Indeed, the performance-energy behavior when mixing workloads is not well understood. This paper presents an interference analysis for heterogeneous workloads (i.e., CPU- and memory-intensive) on a big.LITTLE MPSoC architecture. We employ state-of-the-art tools to generate multiple single-application mappings and characterize the interference among two different services. We observed a performance degradation factor between 1.1 and 2.5. For some configurations, executing on different clusters resulted in reduced energy consumption with no performance penalty. This kind of detailed analysis give us first insights towards more general models for future workload management systems.

<p>  </p> <p>Diabetes, a chronic condition characterized by elevated blood glucose levels, arises when pancreatic β-cells lose capacity to produce a robust, dynamic glucose-stimulated insulin secretion (GSIS) response. Accurate measurement of β-cell health and function <em>ex vivo</em> is thus fundamental to diabetes research, including studies evaluating disease mechanisms, novel drug candidates, and replacement β-cell populations. However, present-day dynamic GSIS assays typically represent end-point measurements, involve expensive commercial perifusion machines, and require time-consuming enzyme-linked immunosorbent assays (ELISA) for insulin detection. Microfluidic devices developed as accessible, low-cost alternatives still rely on secondary ELISAs and suspend islets in liquid medium, limiting their survival <em>in vitro</em>. Here, we present a novel, 3D-printed microphysiological system (MPS) designed to recreate components of <em>in-vivo</em> microenvironments through encapsulation in fibrillar type I collagen and restoration of favorable molecular transport conditions. Following computational-informed design and rapid prototyping, the MPS platform sustained collagen-encapsulated mouse islet viability and cytoarchitecture for 5 days and supported <em>in-situ</em> measurements of dynamic β-cell function. To rapidly detect insulin secretion from β-cells in the MPS, we then developed a highly sensitive electrochemical sensor for zinc (Zn2+), co-released with insulin, based on glassy carbon electrodes modified with bismuth and indium and coated with Nafion. Finally, we validated sensor detection of Zn2+ released from glucose-stimulated INS-1 β-cells and primary mouse islets, finding high correlation with insulin as measured by standard ELISA. Together, the 3D MPS and Zn2+ sensor developed in this dissertation represent novel platforms for evaluating β-cell health and function in a low-cost, user-friendly, and physiologically-relevant manner. </p>

No description available.

[pt] Essa pesquisa possui como objetivo investigar os mecanismos de vigas casteladas quanto à sua estabilidade e interação entre modos de flambagem lateral com torção (FLT) e local do tê comprimido (FT). São verificadas as capacidades resistentes de vigas casteladas e, subsequentemente, uma abordagem baseada no Método da Resistência Direta é proposta. As normatizações e guias de dimensionamento atuais tratam dos modos de falha de maneira pouco clara ao considerar a possível interação entre eles, evidenciando a necessidade de estudos e de um método que considere tais efeitos. É realizado um amplo estudo constituído por um universo de 197 vigas casteladas do tipo Litzka biapoiadas sujeitas à flexão pura por meio de modelagem e simulação por análises de elementos finitos lineares e não lineares de material com imperfeições geométricas. Os modelos são validados e o momento último resistente é computado, bem como os momentos críticos dos modos de flambagem global e local. Por fim, são aplicados os conceitos do Método da Resistência Direta e, através de regressão, são propostas equações para previsão do momento nominal resistente levando em conta a interação entre modos de flambagem global e local. Os resultados são comparados com a atual normatização demonstrando melhores valores de previsão para todos os casos, principalmente os que são governados pelo modo local de falha e/ou pela interação dos modos de flambagem. É evidenciada certa discordância dos resultados propostos pelas normas e guias atuais em alguns casos quanto ao dimensionamento à flexão de vigas casteladas, podendo sub ou superestimar sua resistência. / [en] The objective of this research is to investigate the stability mechanisms of castellated beams and the interaction between lateral-torsional and compression tee local buckling modes. A verification of the strength capacity of castellated beams is carried out. Subsequently, an approach based on the Direct Strength Method is proposed for the design of these beams. The treatment of failure modes by current standards and design guides is unclear when considering possible interactions between buckling modes, thus there is a need for more studies and for the development of a design method that takes into account these effects. Firstly, a comprehensive study of 197 simply supported Litzka castellated beams under pure bending moment is carried out. The study involves finite element analyses considering both linear behavior and nonlinear behavior that, which included both material nonlinearity and geometric imperfection. The models are then validated. After computing the moments associated with critical local and global failure modes, and the ultimate moments, along with their respective modes, an approach based on the Direct Strength Method is performed. Equations that consider the interaction for nominal moments prediction are obtained through regression. The developed equation is then compared with current standards procedures. The results show that the proposed equation predicts better values for strength prediction in all cases, especially those in which local and/or interaction failure modes govern the behavior of the beam. The results also show that some of the procedures suggested in standards and guides for the design of castellated beams under flexure, either underestimate or overestimate the failure moment.

No description available.

[pt] O presente trabalho visa investigar a interação entre a flambagem lateral com torção e a flambagem local do tê comprimido em vigas casteladas. O método dos elementos finitos (MEF) é usado para realizar análises paramétricas de vigas Litzkas sujeitas a flexão pura e considerando combinações da razão entre espessura e comprimento das mesas e alma, além do comprimento destravado. Para considerar a possibilidade de aço com diferentes resistências ao escoamento, esbeltezes adimensionais são utilizadas para prever o comportamento da estrutura de maneira compreensiva. As respostas de vigas com diferentes combinações de esbeltezes são comparadas e a resistência relativa de cada uma delas é discutida. A influência das imperfeições iniciais na capacidade de resistência é avaliada. Os momentos últimos calculados a partir do MEF são comparados com aqueles calculados de acordo com as normas de dimensionamento para vigas casteladas, mostrando que esses podem superestimar ou subestimar as capacidades de resistência. Finalmente, uma abordagem com o método da resistência direta é testada para prever a resistência nominal à flexão. Através das análises feitas, conclui-se que o Design Guide subestima a resistência das geometrias analisadas, o método da resistência direta as superestima e as imperfeições iniciais têm influência no comportamento das vigas analisadas. / [en] The present work aims to investigate the interaction between lateral torsional buckling and compression tee local buckling in castellated beams. The finite element method (FEM) is used to perform a parametric study for Litzka-beams subject to pure bending moment considering combinations of flange-to-web width and thickness ratios and unbraced lengths. To account for the possibility of different yield strengths, non-dimensional local and global slenderness are used to assess the behavior in a comprehensive manner. The responses for beams having different combinations of slendernesses are compared and the relative strengths are discussed. The influence of the initial imperfections on the strength capacity is evaluated. The FEM ultimate bending moments are compared to those calculated according to the current design recommendations for castellated beams, showing that these may either over or underpredict actual capacities. Finally, a direct strength method approach is tested for the prediction of the nominal bending strength. Through the performed analyses it was concluded that the Design Guide underestimate the relative strengths of the analyzed geometries, while the direct strength method overestimated them and the initial imperfections influence the structural behavior of the analyzed beams.

<p dir="ltr">Tuberculosis (TB), caused by <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), and human immunodeficiency virus-1 (HIV) are major public health concerns, individually and in combination. The status of the host immune system, previous <i>Mtb</i> infection and HIV-mediated T cell exhaustion, can have significant impacts on immune dynamics during reinfection. Individuals with asymptomatic latent TB infection (LTBI) may be protected against <i>Mtb </i>reinfection, as demonstrated by animal and <i>in vitro </i>studies. However, the underlying dynamics and protective mechanisms of LTBI are poorly understood. In HIV, long-term infection in children and associated T cell exhaustion leads to weakened immune responses to HIV reinfection. The complexity of these infections, particularly in the context of the heightened vulnerability of HIV+ individuals to TB, underscores the need for novel investigative approaches to study host-pathogen and pathogen-pathogen interactions. To this, we have developed an agent-based model (ABM) as a mechanistic computational tool to simulate the immune response to <i>Mtb </i>and HIV, separately and during coinfection. Our ABM integrates clinical and experimental data; simulates immune cell dynamics between macrophages, CD4+ and CD8+ T cells; and produces emergent granuloma-like structures – a critical response to <i>Mtb</i>. This <i>in silico</i> approach allows us to efficiently explore host-pathogen interactions and their clinical implications. By unraveling the complex interplay of immune cell activation, T cell exhaustion, and pathogen dynamics, our model offers insights that could guide the development of targeted therapies. By quantifying the multifaceted nature of these diseases and their interactions, we highlight the potential of computational approaches in understanding and treating complex diseases, individually and in combination.</p>

La prise de décision entre différentes actions potentielles implique une activité coordonnée dans diverses régions corticales telles que le cortex préfrontal, prémoteur, pariétal et moteur primaire, ainsi que dans des régions sous-corticales interconnectées au sein des ganglions de la base (« basal ganglia », BG). Malgré de nombreuses recherches visant à comprendre le rôle causal de chacune de ces régions dans les processus de prise de décision, la contribution précise des ganglions de la base reste un sujet de débat vigoureux. Il n'est toujours pas clair si les BG joue un rôle primaire dans la délibération entre les choix ou contrôle le compromis vitesse-précision (« speed-accuracy trade-off », SAT) dans la sélection et même l'exécution des actions. Dans cette mémoire, pour étudier cette question, nous avons développé un modèle de réseau neuronal simplifié qui régit la compétition entre les actions potentielles tout en gérant le SAT en ajustant un "signal d'urgence" dépendant du contexte dans les BG. Notre modèle reproduit plusieurs phénomènes clés observés dans des expériences récentes visant à dissocier les processus de délibération et d'engagement. Nos résultats suggèrent que dans une tâche bien pratiquée, contrairement aux régions corticales prémoteur et moteur, le globus pallidus internus (GPi) ne contribue pas au processus de délibération mais contrôle plutôt le SAT et, grâce à son rétrocontrôle positif avec les régions corticales, joue un rôle causal dans l'engagement à un choix. Le modèle simule également les effets des décisions retardées avec une microstimulation électrique non spécifique dans les régions corticales, les décisions biaisées avec une stimulation optogénétique spécifique au choix dans le GPi, et l'effet limité de l'inactivation du GPi sur les décisions prises dans des conditions avec des preuves sensorielles fortes. En résumé, notre modèle propose une réponse simple et testable à la question de longue date de savoir comment le cortex et le BG mettent en oeuvre ensemble les décisions sur l'action. / Deciding between potential actions involves coordinated activity across various cortical areas such as the prefrontal, premotor, parietal, and primary motor cortex, as well as interconnected subcortical regions within the basal ganglia (BG). Despite extensive research aimed at understanding the causal role of each of these regions in decision-making processes, the precise contribution of the basal ganglia remains a topic of vigorous debate. It is still not clear whether the BG plays a primary role in deliberation between the choices or controls the speed-accuracy trade-off (SAT) in selecting and even executing the actions. In this thesis, to address this question, we developed a simplified neural network model that governs the competition between potential actions while managing the SAT by adjusting a context-dependent “urgency signal” in BG. Our model replicates several key phenomena observed in recent experiments designed to dissociate the processes of deliberation and commitment. Our results suggest that in a well-practiced task, unlike premotor and motor cortical regions, globus pallidus internus (GPi) does not contribute to the process of deliberation but instead controls the SAT and, through its positive feedback with cortical regions, plays a causal role in committing to a choice. The model also simulates the effects of delayed decisions with non-specific electrical microstimulation in cortical regions, biased decisions with choice-specific optogenetic stimulation in GPi, and the limited effect of GPi inactivation on decisions made in conditions with strong sensory evidence. In summary, our model proposes a simple and testable answer to the long-standing question of how the cortex and BG together implement decisions about action.