Efficient middleware for database replication

Dissertação de Mestrado em Engenharia Informática

Power-and-area efficient 14-bit 1.5 MSample/s two-stage algorithmic ADC based on a mismatch-insensitive MDAC

IEEE International Symposium on Circuits and Systems, pp. 220 – 223, Seattle, EUA

Efficient digital self-calibration of video-rate pipeline ADCs using white gaussian noise

Proceedings of IEEE, ISCAS 2003, Vol.I, pp. 877-880

Efficient succinic acid production from glycerol by actinobacillus succinogenes using dimethyl sulfoxid as electron acceptor

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

Efficient advertising strategies for the fragrance market

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Noise traders, rational traders, and the rest: A new approach to efficient financial markets

A PhD Dissertation, presented as part of the requirements for the Degree of Doctor of Philosophy from the NOVA - School of Business and Economics

Energy-efficient diversity combining for different access schemes in a multi-path dispersive channel

Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e Computadores

A framework for efficient model transformations

The reported productivity gains while using models and model transformations to develop entire systems, after almost a decade of experience applying model-driven approaches for system development, are already undeniable benefits of this approach. However, the slowness of higher-level, rule based model transformation languages hinders the applicability of this approach to industrial scales. Lower-level, and efficient, languages can be used but productivity and easy maintenance seize to exist. The abstraction penalty problem is not new, it also exists for high-level, object oriented languages but everyone is using them now. Why is not everyone using rule based model transformation languages then? In this thesis, we propose a framework, comprised of a language and its respective environment, designed to tackle the most performance critical operation of high-level model transformation languages: the pattern matching. This framework shows that it is possible to mitigate the performance penalty while still using high-level model transformation languages.

Size-Control Regulation during Regeneration

Functional regeneration of organs upon injury is a key process for animals survival. Contrary to humans, some vertebrates are remarkably competent in regenerating after acute organ or appendage lesions. This advantageous skill allows overcoming limitations in repair even in adult stages, when tissues are fully developed, via a process of epimorphic regeneration. One such organism is the zebrafish, which can regenerate several organs, namely its heart, retina, spinal cord and fins. (...)

Proteomics based approach to understand tissue regeneration

Dissertation presented to obtain the PhD degree in Biochemistry

Unraveling intrinsic mechanisms of Nerve Regeneration

Unlike injury to the peripheral nervous system (PNS), where injured neurons can trigger a regenerative program that leads to axonal elongation and in some cases proper reinnervation, after injury to the central nervous system (CNS) neurons fail to produce the same response. The regenerative program includes the activation of several injury signals that will lead to the expression of genes associated with axonal regeneration. As a consequence, the spawned somatic response will ensure the supply of molecular components required for axonal elongation. The capacity of some neurons to trigger a regenerative response has led to investigate the mechanisms underlying neuronal regeneration. Thus, non-regenerative models (like injury to the CNS) and regenerative models (such as injury to the PNS) were used to understand the differences underlying those two responses to injury. To do so, the regenerative properties of dorsal root ganglion (DRG) neurons were addressed. This particular type of neurons possesses two branches, a central axon, that has a limited capacity to regenerate; and a peripheral axon, where regeneration can occur over long distances. In the first paradigm used to understand the neuronal regeneration mechanisms, we evaluated the activation of injury signals in a non-regenerative model. Injury signals include the positive injury signals, which are described as being enhancers of axonal regeneration by activating several transcription factors. The currently known positive injury signals are ERK, JNK and STAT3. To evaluate whether the lack of regeneration following injury to the central branch of DRG neurons was due to inactivation of these signals, activation of the transcription factors pELK-1, p-c-jun (downstream targets of ERK and JNK, respectively) and pSTAT3 were examined. Results have shown no impairment in the activation of these signals. As a consequence, we further proceed with evaluation of other candidates that could participate in axonal regeneration failure. By comparing the protein profiles that were triggered following either injury to the central branch of DRG neurons or injury to their peripheral branch, we were able to identify high levels of GSK3-β, ROCKII and HSP-40 after injury to the central branch of DRG neurons. While in vitro knockdown of HSP-40 in DRG neurons showed to be toxic for the cells, evaluation of pCRMP2 (a GSK3-β downstream target) and pMLC (a ROCKII downstream target), which are known to impair axonal regeneration, revealed high levels of both proteins following injury to the central branch when comparing with injury to their peripheral one. Altogether, these results suggest that activation of positive injury signals is not sufficient to elicit axonal regeneration; HSP-40 is likely to participate in the cell survival program; whereas GSK3-β and ROCKII activity may condition the regenerative capacity following injury to the nervous system.(...)

Efficient paraconsistent reasoning with rules and ontologies for the semantic web

Ontologies formalized by means of Description Logics (DLs) and rules in the form of Logic Programs (LPs) are two prominent formalisms in the field of Knowledge Representation and Reasoning. While DLs adhere to the OpenWorld Assumption and are suited for taxonomic reasoning, LPs implement reasoning under the Closed World Assumption, so that default knowledge can be expressed. However, for many applications it is useful to have a means that allows reasoning over an open domain and expressing rules with exceptions at the same time. Hybrid MKNF knowledge bases make such a means available by formalizing DLs and LPs in a common logic, the Logic of Minimal Knowledge and Negation as Failure (MKNF). Since rules and ontologies are used in open environments such as the Semantic Web, inconsistencies cannot always be avoided. This poses a problem due to the Principle of Explosion, which holds in classical logics. Paraconsistent Logics offer a solution to this issue by assigning meaningful models even to contradictory sets of formulas. Consequently, paraconsistent semantics for DLs and LPs have been investigated intensively. Our goal is to apply the paraconsistent approach to the combination of DLs and LPs in hybrid MKNF knowledge bases. In this thesis, a new six-valued semantics for hybrid MKNF knowledge bases is introduced, extending the three-valued approach by Knorr et al., which is based on the wellfounded semantics for logic programs. Additionally, a procedural way of computing paraconsistent well-founded models for hybrid MKNF knowledge bases by means of an alternating fixpoint construction is presented and it is proven that the algorithm is sound and complete w.r.t. the model-theoretic characterization of the semantics. Moreover, it is shown that the new semantics is faithful w.r.t. well-studied paraconsistent semantics for DLs and LPs, respectively, and maintains the efficiency of the approach it extends.

Eco-efficient earthen plasters: The influence of the addition of natural fibers.

Clayish earth-based mortars are been recognized, all over the world, as eco-efficient products for plastering. Apart from being a product with low embodied energy when compared to other types of plasters, their application on the interior surface of walls may give a strong contribution for the health and comfort of inhabitants. As part of an ongoing research regarding earth-based plasters this work assesses the influence of the addition of two types of natural fibres – oat straw and typha fiber-wool – on the characteristics of plastering mortars made with a clayish earth. Mechanical and physical characteristics were tested, showing that addition of these fibers contribute to decrease linear drying shrinkage and thermal conductivity, as well as promoting the adhesion strength of plaster to the substrate. The improvement of mechanical resistance reveal to be dependent on the type of fiber added while the hygroscopic capacity of the plaster is maintained regardless of the fiber additions.

Experimental characterization of an earth eco-efficient plastering mortar

Earthen plastering mortars are becoming recognized as highly eco-efficient. The assessment of their technical properties needs to be standardized but only the German standard DIN 18947 exists for the moment. An extended experimental campaign was developed in order to assess multiple properties of a ready-mixed earth plastering mortar and also to increase scientific knowledge of the influence of test procedures on those properties. The experimental campaign showed that some aspects related to the equipment, type of samples and sample preparation can be very important, while others seemed to have less influence on the results and the classification of mortars. It also showed that some complementary tests can easily be performed and considered together with the standardized ones, while others may need to be improved. The plaster satisfied the requirements of the existing German standard but, most importantly, it seemed adequate for application as rehabilitation plaster on historic and modern masonry buildings. Apart from their aesthetic aspect, the contribution of earthen plasters to eco-efficiency and particularly to hygrometric indoor comfort should be highlighted.

EFFECT – Efficient finite element code

The theme of this dissertation is the finite element method applied to mechanical structures. A new finite element program is developed that, besides executing different types of structural analysis, also allows the calculation of the derivatives of structural performances using the continuum method of design sensitivities analysis, with the purpose of allowing, in combination with the mathematical programming algorithms found in the commercial software MATLAB, to solve structural optimization problems. The program is called EFFECT – Efficient Finite Element Code. The object-oriented programming paradigm and specifically the C ++ programming language are used for program development. The main objective of this dissertation is to design EFFECT so that it can constitute, in this stage of development, the foundation for a program with analysis capacities similar to other open source finite element programs. In this first stage, 6 elements are implemented for linear analysis: 2-dimensional truss (Truss2D), 3-dimensional truss (Truss3D), 2-dimensional beam (Beam2D), 3-dimensional beam (Beam3D), triangular shell element (Shell3Node) and quadrilateral shell element (Shell4Node). The shell elements combine two distinct elements, one for simulating the membrane behavior and the other to simulate the plate bending behavior. The non-linear analysis capability is also developed, combining the corotational formulation with the Newton-Raphson iterative method, but at this stage is only avaiable to solve problems modeled with Beam2D elements subject to large displacements and rotations, called nonlinear geometric problems. The design sensitivity analysis capability is implemented in two elements, Truss2D and Beam2D, where are included the procedures and the analytic expressions for calculating derivatives of displacements, stress and volume performances with respect to 5 different design variables types. Finally, a set of test examples were created to validate the accuracy and consistency of the result obtained from EFFECT, by comparing them with results published in the literature or obtained with the ANSYS commercial finite element code.