Novel linear and nonlinear optical signal processing for ultra-high bandwidth communications

The thesis is articulated around the theme of ultra-wide bandwidth single channel signals. It focuses on the two main topics of transmission and processing of information by techniques compatible with high baudrates. The processing schemes introduced combine new linear and nonlinear optical platforms such as Fourier-domain programmable optical processors and chalcogenide chip waveguides, as well as the concept of neural network. Transmission of data is considered in the context of medium distance links of Optical Time Division Multiplexed (OTDM) data subject to environmental fluctuations. We experimentally demonstrate simultaneous compensation of differential group delay and multiple orders of dispersion at symbol rates of 640 Gbaud and 1.28 Tbaud. Signal processing at high bandwidth is envisaged both in the case of elementary post-transmission analog error mitigation and in the broader field of optical computing for high level operations (“optical processor”). A key innovation is the introduction of a novel four-wave mixing scheme implementing a dot-product operation between wavelength multiplexed channels. In particular, it is demonstrated for low-latency hash-key based all-optical error detection in links encoded with advanced modulation formats. Finally, the work presents groundbreaking concepts for compact implementation of an optical neural network as a programmable multi-purpose processor. The experimental architecture can implement neural networks with several nodes on a single optical nonlinear transfer function implementing functions such as analog-to-digital conversion. The particularity of the thesis is the new approaches to optical signal processing that potentially enable high level operations using simple optical hardware and limited cascading of components

Role of micronutrients in medicine

peer reviewedAdequate micronutrient intake throughout life course is essential for the maintenance of health. Micronutrients are necessary for the maintenance of intermediary metabolism, play a crucial role as co-factors or co-enzymes in the activity of virtually all enzymes, and have important functions to neutralise the deleterious effects of oxidant species. Claims have been made for the benefits of micronutrient supplementation. Clinical benefit of a supplementation is obvious in those individuals who are severely depleted and at risk of complications. More recently, the concept of subclinical deficit has been developed, which essentially relies upon biochemical abnormalities the interpretation of which remains doubtful in most instances. Symptomatology related to such subclinical deficit is non specific and the potential advantages of micronutrient supplements remain marginal and largely not well-established. In contrast, provision of excess supplements to individuals who do not need them may be harmful. In the general population, a well-balanced diet supplies an adequate intake of micronutrient. Further research is needed to identify the best markers of micronutrient and antioxidant status, so that at risk patients can be identified and appropriate supplementation provided accordingly. New large-scale trials of different doses of micronutrients, based on precise outcome markers, are required to optimise intakes in different groups of patients as well as in the general population

Which HBA1C and lipid targets in patients with type 2 diabetes?

peer reviewedPatients with type 2 diabetes are at high cardiovascular risk and require a global management targeting all risk factors. Target values for blood pressure have been discussed in a previous paper. The present clinical case summarizes the most important arguments concerning the choice of the target values for glucose control (glycated haemoglobin or HbA1c) and lipid management. As far as glucose control is concerned, the objective should be individually adjusted, based on the benefits/risks ratio, with a less stringent HbA1c level in presence of coronary heart disease and risk of severe hypoglycaemia. However, in absence of these two risks factors, the objective should be reinforced (HbA1c < 7%), essentially to prevent or retard microangiopathic lesions. As far as lipid management is concerned, the most crucial goal remains LDL cholesterol lowering, with a target value < 100 mg/dL in patients at high cardiovascular risk and <70 mg/dL in patients at very high risk, according to the recent European guidelines. Dyslipidaemia related to the metabolic syndrome (hypertriglyceridaemia, low HDL cholesterol) may also represent a therapeutic target (non-HDL cholesterol), although evidence is mostly missing in the literature

Analog readout for optical reservoir computers

Reservoir computing is a new, powerful and flexible machine learning technique that is easily implemented in hardware. Recently, by using a time-multiplexed architecture, hardware reservoir computers have reached performance comparable to digital implementations. Operating speeds allowing for real time information operation have been reached using optoelectronic systems. At present the main performance bottleneck is the readout layer which uses slow, digital postprocessing. We have designed an analog readout suitable for time-multiplexed optoelectronic reservoir computers, capable of working in real time. The readout has been built and tested experimentally on a standard benchmark task. Its performance is better than non-reservoir methods, with ample room for further improvement. The present work thereby overcomes one of the major limitations for the future development of hardware reservoir computers.Comment: to appear in NIPS 201

2015 updated position statement of the management of hyperglycaemia in type 2 diabetes

peer reviewedThe strategy for the management ot type 2 diabetes, summarized by a group of European and American experts, has been updated early 2015. A patient-centered approach is recommended and the first drug choice is metformin combined with lifestyle improvement. After failure of metformin monotherapy, the selection of a second drug should be based on the efficacy, safety and cost of each pharmacological class. When compared to the position statement of 2012, the most important changes are the possible addition of a gliptin to a dual oral therapy or even to insulin, the commercialization of sodium-glucose cotransporters type 2 (SGLT2) inhibitors (gliflozins, to be used in dual or triple therapy, even in combination with insulin) and the possible combination of a glucagon-like peptide-I receptor agonist together with a basal insulin

Metabolically healthy, but obese subjects. First part: definition, pathophysiology and prevalence

peer reviewedAround 30 to 50% of obese subjects are “metabolically normal” (MHO) whereas numerous nonobese subjects are “metabolically abnormal”. The distribution and function of adipose deposits seem to play a crucial role in explaining this apparent paradox. The aim of this first article is to describe the clinical and biological characteristics that lead to the diagnosis of MHO, attempt to discover the etiopathogenesis of this syndrome and analyze the underlying pathophysiological mechanisms and, finally, to assess the prevalence of the MHO phenotype, which may vary according to the definition used and the population studied.Environ 30 à 50 % des sujets obèses sont « métaboliquement normaux » (MHO metabolically healthy, but obese) alors qu’inversement, nombre de sujets non obèses sont « métaboliquement anormaux ». La topographie et la fonction des dépôts graisseux semblent jouer un rôle déterminant pour expliquer cet apparent paradoxe. Ce premier article vise à présenter les éléments conduisant au diagnostic du phénotype MHO, à tenter d’en cerner l’étiopathogénie et de mieux comprendre sa physiopathologie et, enfin, à analyser la prévalence de ce syndrome, quelque peu différente en fonction de la définition retenue et de la population étudiée

Fitness versus fatness: Respective cardiometabolic impacts in children/adolescents and in elderly people

peer reviewedLe sujet adulte d’âge moyen en surpoids ou obèse est caractérisé par une adiposité exagérée, généralement combinée à une aptitude physique cardio-respiratoire déficiente. La pratique régulière d’une activité physique d’endurance améliore le profil de risque cardio-métabolique dans cette tranche d’âge. Le manque d’activité physique chez les adolescents contribue à augmenter leur masse grasse et à induire des anomalies métaboliques, tandis que la sédentarité marquée des sujets âgés peut conduire à un excès de graisse combiné à une fonte musculaire (obésité sarcopénique). Dans ces deux tranches d’âge, les effets néfastes d’un excès de masse grasse (fatness) pourraient être contrecarrés, voire annulés, par la pratique régulière d’exercices musculaires conduisant à une meilleure aptitude physique (fitness). Cet article décrit les relations entre fitness et fatness, et les impacts cardio-métaboliques respectifs de ces deux composantes, d’une part, dans la population jeune ( 60 ans)

LA STEAM EXPLOSION : PRINCIPE ET ACTION SUR LES MATERIAUX LIGNOCELLULOSIQUES

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites par la formation d’acides organiques et du cisaillement résultant de la chute brutale de pression. Le procédé est composé de deux phases distinctes. D’une part, le vapocraquage qui consiste à faire pénétrer par diffusion, puis à condenser, la vapeur sous haute pression à l’intérieur de la structure du matériau. L’eau condensée à température élevée va initier l’hydrolyse des groupements acétyles contenus dans les xylanes et induire la formation d’acides organiques. Selon la sévérité des conditions (pression, température), les acides vont catalyser l’hydrolyse des fractions hémicellulosiques, induire des modifications dans la structure des lignines et modifier le degré de cristallinité de la fraction cellulosique. D’autre part, la décompression explosive. Cette phase est provoquée par une chute brutale de pression qui va entraîner la revaporisation d’une partie de l’eau condensée. L’expension brutale de la vapeur va induire des forces de cisaillement qui vont modifier les propriétés physiques (granulométrie, surface spécifique, rétention d’eau…) du matériau.LIGNOFUE

Carbohydrate-Based Surfactants: Structure-Activity Relationships

The aim of the present contribution is: (1) to review CBS in terms of structural classification based on their molecular size (mono-, oligo-, polymeric surfactants), geometry (standard, bipolar or bolaform, and gemini surfactants), and the nature of the polar headgroup (charged or not, cyclic or not), the apolar tail (number and length of alkyl chain), and the linker (amide, ester, ...) and/or the spacer; (2) to present systematically results on structure- activity relationships of uronic acid derivatives (UADs), a particular class of carbohydrate-based surfactants. These concern the impact of each structural entity including the polar headgroup (stereochemistry), apolar tail (chain length, number, and unsaturation), and linkage/spacer, on the performance of UADs to change surface properties, and possibly, to form and stabilize colloidal systems