Ultrafast quantitative 2D NMR: an efficient tool for the measurement of specific isotopic enrichments in complex biological mixtures

Two-dimensional nuclear magnetic resonance (2D NMR) is a promising tool for studying metabolic fluxes by measuring (13)C-enrichments in complex mixtures of (13)C-labeled metabolites. However, the methods reported so far are hampered by very long acquisition durations limiting the use of 2D NMR as a quantitative tool for fluxomics. In this paper, we propose a new approach for measuring specific (13)C-enrichments in a very fast way, by using new experiments based on ultrafast 2D NMR. Two homonuclear 2D experiments (ultrafast COSY and zTOCSY) are proposed to measure (13)C-enrichments in a single scan. Their advantages and limitations are discussed, and their high analytical potentialities are highlighted. Both methods are characterized by an accuracy of 1-2%, an average precision of 3%, and an excellent linearity. The analytical performance is equivalent or better than any of the conventional methods previously reported. The two ultrafast experiments are applied to the measurement of (13)C-enrichments on a biomass hydrolyzate, showing the first known application of ultrafast 2D NMR to a real biological extract. The experiment duration is divided by 200 compared to the conventional methods, while preserving 80% of the quantitative information. This new approach opens new perspectives of application for fluxomics and metabonomics.     

Temperature coefficient of the high-frequency guided acoustic mode in a photonic crystal fiber

High-frequency guided acoustic Brillouin modes have recently been observed in small-core silica photonic crystal fibers. In this paper, we investigate the temperature dependence of the optical sideband frequency generated by one of these guided acoustic waves. The experimental results show a temperature coefficient of 100 kHz/°C at an acoustic resonance frequency of 1.15 GHz and are in very good agreement with the theoretical predictions. This coefficient demonstrates a temperature sensitivity 10 times larger than that previously reported in conventional single-mode fibers, which is promising in view of potential applications to optical fiber sensors.     

Combustion with mixed enrichment of oxygen and hydrogen in lean regime

A low global richness of combustion is interesting from an ecological and economic point of view as it helps to limit fuel consumption. In fact, the consequences of the combustion in poor mode are the appearance of local or global flame extinctions, energy loss by radiation and change in flame structure. The flammability limits of the diffusion methane flame can be resolved by the enrichment of the combustion air with oxygen or the use of the pure oxygen as oxidant as well as the addition to hydrogen in natural gas. Moreover, the use of oxygen and hydrogen as previously mentioned allow working in low ranges of richness while maintaining good flame stability. For a constant burner power of 15 kW, the reduction of the richness involves an increase in the oxidizer flow rate injected into the combustion reaction. In this present study, the variation of the richness, the fuel enrichment with hydrogen and the oxidant enrichment with oxygen are shown as major parameters where they have direct influences on the flow dynamic, the flame structure and the pollutant emissions.The Chemiluminescence of OH* radical and the PIV (Particle image velocimetry) are used in this work to characterize the flame structure, the stability and the dynamics of the flame. The measurement of pollutant emissions effected by a gas analyzer. The enrichment in oxygen and hydrogen provides a stable flame, which is well attached to the burner for the following richness values: 0.7, 0.8, 0.9 and 1. The reduction of the richness promotes the mixture quality of the reactants and leads a reduction in CO₂ and CO concentration. By contrast, the decrease of the richness supports the formation of NOx.     

A Model for Impedance Determinations and Power Deposition Characterization in Three-Electrode Configurations for Capacitive Radio Frequency Hyperthermia?Part B: Current Flow and Power Deposition

The 2-D rectangular model for three-electrode radio frequency hyperthermia applicators established in Part A is applied to the determination of the current lines and the potential lines inside the system. Any electrode voltage distributions can be considered. Two figures illustrate the impact of the electric and the geometric parameters on these lines. They show that important changes in local current density, in electric field strength, and in electric field orientation are tied to the adjustments of the relevant parameters. Two successive sampling processes lead to the determination of the local power deposition. The figures which are displayed demonstrate the ability to move this deposition inside any useful area by means of proper trimming of the electrode voltage phases and magnitudes.     

Concurrence entre réseaux de télécommunications: les conséquences des externalités négatives *

The authors offer a theoretical model for studying the consequences of competition between long distance telecommunications networks. Contrarily to a recent paper by Katz-Shapiro, from which our model is inspired, we put the stress on negative externalities. In this context, we prove that competition is very likely to imply degradation of the quality of the services offered to the customers.     

An improved approximation algorithm for the two-machine open shop scheduling problem with family setup times

We consider the problem of scheduling families of jobs in a two-machine open shop so as to minimize the makespan. The jobs of each family can be partitioned into batches and a family setup time on each machine is required before the first job is processed, and when a machine switches from processing a job of some family to a job of another family. For this NP-hard problem the literature contains (5/4)-approximation algorithms that cannot be improved on using the class of group technology algorithms in which each family is kept as a single batch. We demonstrate that there is no advantage in splitting a family more than once. We present an algorithm that splits one family at most once on a machine and delivers a worst-case performance ratio of 6/5.     

Biological Functions and Metabolism of Oleoylethanolamide

The present review is focused on the metabolism and the emerging roles of oleoylethanolamide (OEA) with emphasis on its effects on food intake control and lipid metabolism. The biological mechanism of action, including a non-genomic effect mediated through peroxisome proliferator-activated receptor alpha (PPAR-alpha) and transient receptor potential vanilloid type 1 (TRPV1) receptor, is discussed. The research related to fatty acid ethanolamides has been focused until recently on anandamide and its interaction with cannabinoid receptor subtype 1. The roles of other N-acyl ethanolamine fatty acid derivatives have been neglected until it was demonstrated that OEA can modulate food intake control through interaction with PPAR-alpha. Further investigations demonstrated that OEA modulates lipid and glucose metabolism, and recent study confirmed that OEA is an antagonist of TRVP1. It has been demonstrated that OEA has beneficial effects on health by inducing food intake control, lipid beta-oxidation, body weight loss and analgesic effects. The investigation of the mechanism of action revealed that OEA activates PPAR-alpha and stimulates the vagal nerve through the capsaicin receptor TRPV1. Pre-clinical studies showed that OEA remains active when administered orally.     

An overview of the history of Science of Science in China based on the use of bibliographic and citation data: a new method of analysis based on clustering with feature maximization and contrast graphs

In the first part of this paper, we shall discuss the historical context of Science of Science both in China and at world level. In the second part, we use the unsupervised combination of GNG clustering with feature maximization metrics and associated contrast graphs to present an analysis of the contents of selected academic journal papers in Science of Science in China and the construction of an overall map of the research topics’ structure during the last 40 years. Furthermore, we highlight how the topics have evolved through analysis of publication dates and also use author information to clarify the topics’ content. The results obtained have been reviewed and approved by 3 leading experts in this field and interestingly show that Chinese Science of Science has gradually become mature in the last 40 years, evolving from the general nature of the discipline itself to related disciplines and their potential interactions, from qualitative analysis to quantitative and visual analysis, and from general research on the social function of science to its more specific economic function and strategic function studies. Consequently, the proposed novel method can be used without supervision, parameters and help from any external knowledge to obtain very clear and precise insights about the development of a scientific domain. The output of the topic extraction part of the method (clustering?+?feature maximization) is finally compared with the output of the well-known LDA approach by experts in the domain which serves to highlight the very clear superiority of the proposed approach.

     

Mixing Static and Dynamic Partitioning to Parallelize a Constraint Programming Solver

This paper presents an external parallelization of Constraint Programming (CP) search tree mixing both static and dynamic partitioning. The principle of the parallelization is to partition the CP search tree into a set of sub-trees, then assign each sub-tree to one computing core in order to perform a local search using a sequential CP solver. In this context, static partitioning consists of decomposing the CP variables domains in order to split the CP search tree into a set of disjoint sub-trees to assign them to the cores. This strategy performs well without adding an extra cost to the parallel search, but the problem is the load imbalance between computing cores. On the other hand, dynamic partitioning is based on preservation of the search state to generate, dynamically or on demand, the sub-trees that are assigned to the cores. This strategy offers good load balancing between the different computing cores, but computing overcosts appear due to the initialisation of the search when a sub-tree is migrated from one core to another. In this paper, we propose a new partitioning strategy that mixes the static and dynamic partitioning and enjoys the benefits of each strategy. This mixed partitioning is designed to run on shared and distributed memory architectures. The performances obtained are illustrated by solving the CP problems modelled using the FlatZinc format and solved using the Google OR-Tools solver on top of the parallel Bobpp framework.