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See detailSociality and Self-Organisation in Next-Generation Distributed Environments
Botev, Jean UL

Doctoral thesis (2011)

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br ... [more ▼]

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br />Distributed virtual environments constitute a privileged example, involving a high degree of interactivity as well as tightened constraints and requirements. As a response to these issues, this dissertation explores and substantiates sociality as a fundamental principle both in and for the design of such systems.<br />A specialized, dual peer-to-peer architecture is introduced, combining a highly-structured backbone overlay with a loosely-structured geometric client overlay synergistically complementing each other. To enable a global-scale, single-instanced environment, it is imperative to include as many client-side resources as possible and unburden the backbone. The focus of this dissertation therefore lies upon the latter, geometric overlay.<br />By taking an interdisciplinary perspective and leveraging different aspects of sociality, a series of self-organized approaches addressing major problem areas are proposed: a collaborative filtering mechanism for the handling of information overload created from the soaring amounts of users and objects; a confidentiality framework for the protection of sensitive data more likely exposed due to an increased interactivity; and two resource allocation schemes for fairly distributing surplus capacities in the face of critical regional surges.<br />Detailed evaluations show that these decentralized algorithms operate robustly and effectively, while yielding well-converging results in comparison to optimal, global-knowledge scenarios. [less ▲]

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See detailEthylmalonyl-CoA decarboxylase, a new enzyme involved in metabolite proofreading
Linster, Carole UL; Noël, Gaëtane; Stroobant, Vincent et al

in Journal of Biological Chemistry (2011), 286(50), 42992-3003

A limited number of enzymes are known that play a role analogous to DNA proofreading by eliminating non-classical metabolites formed by side activities of enzymes of intermediary metabolism. Because few ... [more ▼]

A limited number of enzymes are known that play a role analogous to DNA proofreading by eliminating non-classical metabolites formed by side activities of enzymes of intermediary metabolism. Because few such "metabolite proofreading enzymes" are known, our purpose was to search for an enzyme able to degrade ethylmalonyl-CoA, a potentially toxic metabolite formed at a low rate from butyryl-CoA by acetyl-CoA carboxylase and propionyl-CoA carboxylase, two major enzymes of lipid metabolism. We show that mammalian tissues contain a previously unknown enzyme that decarboxylates ethylmalonyl-CoA and, at lower rates, methylmalonyl-CoA but that does not act on malonyl-CoA. Ethylmalonyl-CoA decarboxylase is particularly abundant in brown adipose tissue, liver, and kidney in mice, and is essentially cytosolic. Because Escherichia coli methylmalonyl-CoA decarboxylase belongs to the family of enoyl-CoA hydratase (ECH), we searched mammalian databases for proteins of uncharacterized function belonging to the ECH family. Combining this database search approach with sequencing data obtained on a partially purified enzyme preparation, we identified ethylmalonyl-CoA decarboxylase as ECHDC1. We confirmed this identification by showing that recombinant mouse ECHDC1 has a substantial ethylmalonyl-CoA decarboxylase activity and a lower methylmalonyl-CoA decarboxylase activity but no malonyl-CoA decarboxylase or enoyl-CoA hydratase activity. Furthermore, ECHDC1-specific siRNAs decreased the ethylmalonyl-CoA decarboxylase activity in human cells and increased the formation of ethylmalonate, most particularly in cells incubated with butyrate. These findings indicate that ethylmalonyl-CoA decarboxylase may correct a side activity of acetyl-CoA carboxylase and suggest that its mutation may be involved in the development of certain forms of ethylmalonic aciduria. [less ▲]

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See detailWhen numbers act as attentional cues: behavioral, EEG and fMRI investigations
Schiltz, Christine UL

Presentation (2011, December 16)

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See detailComparison between the Transfer Functions of three Superconducting Gravimeters
Francis, Olivier UL; Lampitelli, Carmine UL; Klein, Gilbert UL et al

in Marées Terrestres Bulletin d'Informations (2011), 147

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See detailA Multi-objective GRASP Algorithm for Joint Optimization of Energy Consumption and Schedule Length of Precedence-Constrained Applications
Pecero, Johnatan UL; Bouvry, Pascal UL; Fraire Huacuja, Hector J. et al

in 2011 IEEE Ninth International Conference on Dependable, Autonomic and Secure Computing (DASC) (2011, December 14)

We address the problem of scheduling precedence-constrained scientific applications on a heterogeneous distributed processor system with the twin objectives of minimizing simultaneously energy consumption ... [more ▼]

We address the problem of scheduling precedence-constrained scientific applications on a heterogeneous distributed processor system with the twin objectives of minimizing simultaneously energy consumption and schedule length. Previous research efforts on scheduling have focused on the minimization of a quality of service metric based on the completion time of applications (e.g., the schedule length). Recently, many researchers are working on the design of new scheduling algorithms that consider the minimization of energy consumption. We report a new scheduling algorithm accounting for both objectives. The new scheduling algorithm is based on a multi-start randomized adaptive search technique (GRASP framework) that adopts Dynamic Voltage Scaling technique to minimize energy consumption. This technique enables processors to operate in different voltage supply levels at the cost of sacrificing clock frequencies. This multiple voltage implies a trade-off between the quality of the schedules and energy consumption. Therefore, the new proposed approach is designed as a multi-objective algorithm that simultaneously optimize both objectives. Simulation results on a set of real-world applications emphasize the robust performance of the proposed approach. [less ▲]

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See detailTheoretical extensions: From Interactive to Collaborative Problem Solving
Greiff, Samuel UL; Funke, J.

Scientific Conference (2011, December 13)

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See detailSome thoughts on the assessment of Collaborative Problem Solving.
Greiff, Samuel UL; Fischer, A.; Funke, Joachim

Scientific Conference (2011, December 12)

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See detailAnalysis of critical transitions in Parkinson's disease
Trefois, Christophe UL; Antony, Paul UL; Baumuratov, Aidos UL et al

Poster (2011, December 12)

Background Parkinson’s disease is the most common neurodegenerative movement disorder and is clinically characterized by resting tremor, bradykinesia and cogwheel rigidity. The disease affects 1-2% of the ... [more ▼]

Background Parkinson’s disease is the most common neurodegenerative movement disorder and is clinically characterized by resting tremor, bradykinesia and cogwheel rigidity. The disease affects 1-2% of the global population with prevalence in the people above 65 years of age. The main pathological hallmark of Parkinson’s disease is a progressive loss of dopaminergic neurons in the substantia nigra. Therefore, one important challenge is to improve the understanding of regime shifts between health and disease states. Improving predictions of critical transitions triggering the onset of parkinsonian phenotypes could contribute to the improvement of preventive treatments. Methods Based on cellular models, we will use the mathematical concept of critical transitions to create a toolbox for potentially predicting tipping points towards cellular Parkinson’s disease phenotypes, e.g. mitochondrial dysfunction. Experimentally, we will induce and analyze potential critical transitions in the SH-SY5Y cell line. To do this, we will apply Parkinson’s disease relevant chemical and genetic perturbations and analyze multiple scales of the resulting temporal system behavior. We will combine high content imaging with genetic and biochemical data. A significant informatics challenge arises from the aim to perform the analysis of high time-resolved 3D imaging data. We are therefore developing an automated image analysis pipeline that relies on latest technologies and techniques, such as 3D deconvolution and 3D particle tracking. This pipeline will be applied to study parameters, such as mitochondrial dynamics, which include for instance velocity, morphology, and spatial organization. [less ▲]

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See detailAssociation between age, IL-10, IFNγ, stimulated C-peptide and disease progression in children with newly diagnosed Type 1 diabetes
Kaas, A.; Pfleger, C.; Kharagjitsingh, A.V. et al

in Diabetic Medicine : A Journal of the British Diabetic Association (2011)

AIMS: The relation of disease progression and age, serum interleukin 10 (IL-10) and interferon gamma (IFNγ) and their genetic correlates were studied in paediatric patients with newly diagnosed Type 1 ... [more ▼]

AIMS: The relation of disease progression and age, serum interleukin 10 (IL-10) and interferon gamma (IFNγ) and their genetic correlates were studied in paediatric patients with newly diagnosed Type 1 diabetes. METHODS: Two hundred and twenty-seven patients from the Hvidoere Study Group were classified in four different progression groups as assessed by change in stimulated C-peptide from 1 to 6 months. CA repeat variants of the IL-10 and IFNγ gene were genotyped and serum levels of IL-10 and IFNγ were measured at 1, 6 and 12 months. RESULTS: IL-10 decreased (P < 0.001) by 7.7% (1 month), 10.4% (6 months) and 8.6% (12 months) per year increase in age of child, while a twofold higher C-peptide concentration at 1 month (p = 0.06), 6 months (P = 0.0003) and 12 months (P = 0.02) was associated with 9.7%, 18.6% and 9.7% lower IL-10 levels, independent of each other. IL-10 concentrations did not associate with the disease progression groups. By contrast, IFNγ concentrations differed between the four progression groups at 6 and 12 months (P = 0.02 and P = 0.01, respectively); patients with rapid progressing disease had the highest levels at both time points. Distribution of IL-10 and IFNγ genotypes was equal among patients from the progression groups. CONCLUSION: IL-10 serum levels associate inversely with age and C-peptide. As age and C-peptide also associate, a triangular association is proposed. Genetic influence on IL-10 production seems to be masked by distinct disease mechanisms. Increased serum IFNγ concentrations associate with rapid disease progression. Functional genetic variants do not associate with a single progression pattern group, implying that disease processes override genetically predisposed cytokine production. [less ▲]

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See detailAnalysis of the salary distribution in Luxembourg - a finite mixture approach
Schiltz, Jang UL; Guigou, Jean-Daniel UL; Lovat, Bruno et al

Scientific Conference (2011, December 11)

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See detailGermaine Tailleferre
Anders-Malvetti, Ursula UL

in Borchard, Beatrix (Ed.) Musik und Gender im Internet (2011)

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See detailGlory and Hallelujah. Choir Singing for Young at Heart
Sagrillo, Damien UL

Scientific Conference (2011, December 08)

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See detailExtremely conserved ATP- or ADP-dependent enzymatic system for nicotinamide nucleotide repair
Marbaix, Alexandre Y.; Noël, Gaëtane; Detroux, Aline M. et al

in Journal of Biological Chemistry (2011), 286(48), 41246-52

The reduced forms of NAD and NADP, two major nucleotides playing a central role in metabolism, are continuously damaged by enzymatic or heat-dependent hydration. We report the molecular identification of ... [more ▼]

The reduced forms of NAD and NADP, two major nucleotides playing a central role in metabolism, are continuously damaged by enzymatic or heat-dependent hydration. We report the molecular identification of the eukaryotic dehydratase that repairs these nucleotides and show that this enzyme (Carkd in mammals, YKL151C in yeast) catalyzes the dehydration of the S form of NADHX and NADPHX, at the expense of ATP, which is converted to ADP. Surprisingly, the Escherichia coli homolog, YjeF, a bidomain protein, catalyzes a similar reaction, but using ADP instead of ATP. The latter reaction is ascribable to the C-terminal domain of YjeF. This represents an unprecedented example of orthologous enzymes using either ADP or ATP as phosphoryl donor. We also show that eukaryotic proteins homologous to the N-terminal domain of YjeF (apolipoprotein A-1-binding protein (AIBP) in mammals, YNL200C in yeast) catalyze the epimerization of the S and R forms of NAD(P)HX, thereby allowing, in conjunction with the energy-dependent dehydratase, the repair of both epimers of NAD(P)HX. Both enzymes are very widespread in eukaryotes, prokaryotes, and archaea, which together with the ADP dependence of the dehydratase in some species indicates the ancient origin of this repair system. [less ▲]

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