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This work presents an experimental study to investigate the effect of the electromagnetic on the tap water properties of water. The water flows through a closed loop with a speed of 0.18m/s, while the pH, TDS, and hardness represent its properties. For magnetized water using the aqua 4D device. the conductivity, TDS, salinity, temperature, absorbance at 631 nm and the turbidity of magnetized water increase respectively by 3.66%, 4%, 4.4%, 0.76%, 21.64%, and 62.6% compared to those of tap water, while density, resistivity, transmission and pH decrease by 2%, 4.1%, 1.32%, and 3.32% respectively

International audience; Rationale: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown.Objectives: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2

In this paper we review recent discrepancy bounds for ( t , s ) -sequences and other low-discrepancy sequences. We then provide numerical comparisons of these bounds for various combinations of dimension and number of points. In some cases, we compare different bounds for the same type of construction, and in other cases, we compare the best bounds across different constructions.

We present different implementations for the irreducible Sobol’ (IS) sequences introduced in Faure and Lemieux (2016). For this purpose we retain two strategies: first we use the connection between IS and Niederreiter sequences to provide a very simple implementation requiring no computer search; then we use criteria measuring the equidistribution to search for good parameters. Numerical results comparing these IS sequences to known implementations show promise for the proposed approaches.

International audience; Fifteen recommendations and a therapeutic algorithm regarding the management of acute respiratory distress syndrome (ARDS) at the early phase in adults are proposed. The Grade of Recommendation Assessment, Development and Evaluation (GRADE) methodology has been followed. Four recommendations (low tidal volume, plateau pressure limitation, no oscillatory ventilation, and prone position) had a high level of proof (GRADE 1 + or 1 -); four (high positive end-expiratory pressure [PEEP] in moderate and severe ARDS, muscle relaxants, recruitment maneuvers, and venovenous extracorporeal membrane oxygenation [ECMO]) a low level of proof (GRADE 2 + or 2 -); seven (surveillance, tidal volume for non ARDS mechanically ventilated patients, tidal volume limitation in the presence of low plateau pressure, PEEP > 5 cmH2O, high PEEP in the absence of deleterious effect, pressure mode allowing spontaneous ventilation after the acute phase, and nitric oxide) corresponded to a level of proof that did not allow use of the GRADE classification and were expert opinions. Lastly, for three aspects of ARDS management (driving pressure, early spontaneous ventilation, and extracorporeal carbon dioxide removal), the experts concluded that no sound recommendation was possible given current knowledge. The recommendations and the therapeutic algorithm were approved by the experts with strong agreement.

Confrontee au vieillissement de ses endiguements et a des conditions d'acces parfois degradees, la Compagnie Nationale du Rhone, 2eme producteur d'hydro electricite francais, souhaite developper de nouveaux systemes d'auscultation complementaires aux capteurs et inspections visuelles deja deployes sur ses ouvrages.Les developpements des drones, des capteurs photographiques et des algorithmes de calculs automatiques de modelisation 3D a partir d'images multi-stereoscopiques permettent aujourd'hui d'obtenir la geometrie fine d'ouvrages lineaires via des modeles 3D. Actuellement, avec un reseau de point au sol dense, la precision atteignable est de l'ordre de 5 cm.Afin de pouvoir atteindre les precisions souhaitees (± 1 cm a ± 3 cm) tout en minimisant le nombre de points au sol, et donc le temps terrain, la CNR et l'Institut Nationale de l'Information Geographique et Forestiere (IGN), ont mis en place un partenariat aboutissant a la realisation d'une these de recherche sur la metrologie par photogrammetrie aeroportee legere appliquee au suivi d'evolution de digues.L'article s'attache a presenter dans un premier temps le contexte du projet a travers la description de la surveillance actuelle des endiguements et des nouveaux besoins en auscultation de la CNR. La suite s'appuie sur une etude de cas sur la digue de la Paliere pour presenter les avancees des methodes photogrammetriques qui permettent a mi 2015 d'atteindre des precisions centimetriques avec seulement 1 point de calage au sol par tranche de 100 metres.Situe a la croisee du monde des drones, de la recherche en algorithmes photogrammetriques et des besoins de concessionnaires d'ouvrages, ce projet debouchera fin 2015 sur un systeme d'auscultation renforce permettant un suivi centimetrique de zones sensibles des endiguements CNR. Les nouveaux algorithmes photogrammetriques ecrits dans un environnement open-source seront ouverts a l'ensemble de la communaute scientifique et les problematiques resolues (mesures georeferencees de haute precision sur des ouvrages lineaires) seront utilisables par d'autres concessionnaires ou prestataires sur d'autres ouvrages presentant la meme geometrie.

International audience; Sobol’ sequences are a popular family of low-discrepancy sequences, in spite of requiring primitive polynomials instead of irreducible ones in later constructions by Niederreiter and Tezuka. We introduce a generalization of Sobol’ sequences that removes this shortcoming and that we believe has the potential of becoming useful for practical applications. Indeed, these sequences preserve two important properties of the original construction proposed by Sobol’: their generating matrices are non-singular upper triangular matrices, and they have an easy-to-implement column-by-column construction. We prove they form a subfamily of the wide family of generalized Niederreiter sequences, hence satisfying all known discrepancy bounds for this family. Further, their connections with Niederreiter sequences show these two families only have a small intersection (after reordering the rows of generating matrices of Niederreiter sequences in that intersection).

Unmanned Aerial Vehicles (UAV) and photogrammetry are two fields that have been boosted these last years. Using aerial means, one can easily acquire aerial data and produce high resolution dense surface models, orthophotos,... IGN (the French Mapping Agency) and CNR (Compagnie Nationale du Rhône, which is the concessionary of the Rhône river and a hydraulic energy producer) have associated themselves on a thesis protect. The aim is to be able to monitor dykes from images acquired by UAV and take benefit from their convenience, targeting a centimetric accuracy on the Z-axis. This article presents our motivations and the problems we have faced in our first experiments. We also worked on a site covered by a terrestrial Lidar survey, and studied how minimizing the bundle adjustment residuals by using different calibrations would influence the quality of the computed models. Finally, we will introduce in a last part our last experiments to get a better understanding of poses estimation accuracy.

The photogrammetric treatment of images acquired on a linear axis is a problematic case. Such tricky configurations often leads to bended 3D models, described as a bowl effect, which requires ground measurements to be fixed. This article presents different solutions to overcome that problem. All solutions have been implemented into the free open-source photogrammetric suite MicMac. The article presents the lasts evolutions of MicMac's bundle adjustment core, as well as some extended calibration models and how they fit for the camera evaluated. The acquisition process is optimized by presenting how oblique images can improve the accuracy of the orientations, while the 3D models accuracies are assessed by producing a millimeter accurate ground truth from terrestrial photogrammetry.

We revisit Atanassov’s methods for Halton sequences, ( t , s ) -sequences, and ( t , e , s ) -sequences by providing a unifying framework enlightening the power and the efficiency of these methods for the study of low-discrepancy sequences. In this context, we obtain new improved explicit bounds for the star-discrepancy of these sequences, showing in most cases a better behavior than preceding ones in the non-asymptotic regime. Theoretical comparisons of discrepancy bounds in the non-asymptotic regime are much more difficult to achieve than in the asymptotic regime, where results exist to compare the leading constants c s . Hence in this paper we mostly proceed via numerical comparisons to compare bounds. But in the case of ( t , s ) -sequences in base 2, we are able to compare two discrepancy bounds and prove that one is demonstrably better than the other for any N ≥ 2 s . The proof is far from trivial as the two bounds are based on different combinatorial arguments.

The term low-discrepancy sequences is widely used to refer to s -dimensional sequences X for which the bound D ∗ ( N , X ) ≤ c s ( log N ) s + O ( ( log N ) s − 1 ) is satisfied, where D ∗ denotes the usual star discrepancy. In this paper, we study such bounds for ( t , s ) -sequences and a newer class of low-discrepancy sequences called ( t , e , s ) -sequences, introduced recently by Tezuka (2013). In the first case, by using a combinatorial argument coupled with a careful worst-case analysis, we are able to improve the discrepancy bounds from Faure and Lemieux (2012) for ( t , s ) -sequences. In the second case, an adaptation of the same pair of arguments allows us to improve the asymptotic behavior of the bounds from Tezuka (2013) in the case of even bases.

Developers and operators of a full range of hydroelectricity structures (500 kms of dykes, 19 in-stream structures and 12 high-head installations) for over 100 years, CNR and SHEM are required to guarantee a constant monitoring of their infrastructure to ensure hydraulic safety, meet their regulatory requirements and to be prepared to new challenges: improved efficiencies, optimised monitoring of high risks areas and information sharing between the different operators. To reach a better surveillance and improve risk management, CNR and SHEM called upon the Advitam Group to set up, in less than 12 months, the innovative software solution ‘ALOHA’ for the inspections and monitoring of their structures to a better knowledge of risk. This monitoring is ensured by over 15,000 sensors, allowing an analysis of historic data spread over 30 years. ALOHA, a development based on the ScanPrint® web based software, allows the full range of operators to collect, visualise, analyse and edit all of the auscultation and monitoring data in an integrated platform. To respond to the specific needs of CNR and SHEM, innovative modules were developed for both in-office work and mobile tools. This article will detail the functional requirements of the CNR and SHEM, the solutions proposed by Advitam with the ALOHA system and the integration of the solution in the risk management.

Aménageurs et exploitants, depuis plus 100 ans, d’un ensemble d’ouvrages varié (500 km d’endiguements, 19 ouvrages au fil de l’eau et 12 de haute et moyenne chute) CNR et SHEM doivent assurer une auscultation constante pour garantir la sûreté hydraulique, assurer la pérennité de ces ouvrages, répondre aux exigences réglementaires et aux nouveaux défis : meilleure efficience, optimisation de la surveillance des zones à forts enjeux et partage des informations entre tous les acteurs. L’auscultation est assurée par plus de 15 000 dispositifs permettant une analyse sur un historique de plus de 30 ans. CNR et la SHEM ont fait appel à la société ADVITAM pour mettre en œuvre, en moins de 12 mois, une solution logicielle innovante ALOHA pour l’auscultation des ouvrages. ALOHA, développé à partir du logiciel ScanPrint®, permet via une interface Web, à l’ensemble des acteurs de saisir, valider les mesures et visualiser, analyser et éditer l’ensemble des données d’auscultation et de surveillance des ouvrages. Pour répondre aux besoins spécifiques de CNR et de SHEM, des modules novateurs ont été développés tant pour les postes fixes que sur les outils de mobilité. L’article détaillera les exigences fonctionnelles de CNR et de SHEM et les réponses proposées par ADVITAM avec la solution ALOHA.

International audience; This study evaluates the long-term performance of two types of geotextiles that were used for 18 years in drainage trenches to stabilize slopes in the French Alps. The flow rate analysis of each trench enabled estimating an average permittivity at trench scale of between 10^-5 and 10^-6 s^-1. After exhuming the geotextiles, their hydraulic and mechanical properties were assessed. The hydraulic tests performed on geotextiles alone gave permittivities greater than 10^-3 s^-1. Gradient ratio tests were performed on undisturbed soil/geotextile/drainage specimens and gave results in the order of 10^-8 s^-1. The aged specimens were examined using scanning electron microscopy. Quantifying the overall performance of the geotextile filter is complicated because of the brittleness of the calcite crust and the subsequent difficulty of characterizing undisturbed interfaces. Various possible explanatory mechanisms involved in the deterioration of trench performance were reviewed: filter cake blinding, internal clogging and downstream chemical clogging. Existing analytical models were used in order to predict the loss of hydraulic performance due to each of these clogging mechanisms. By comparing the measured permittivities to the calculated permittivities, we demonstrated that chemical clogging due to calcite precipitation on the downstream face of the geotextiles was probably the preponderant mechanism responsible for the poorer performance of geotextile filters at trench scale.

International audience

In 1935 J.G. van der Corput introduced a sequence which has excellent uniform distribution properties modulo 1. This sequence is based on a very simple digital construction scheme with respect to the binary digit expansion. Nowadays the van der Corput sequence, as it was named later, is the prototype of many uniformly distributed sequences, also in the multi-dimensional case. Such sequences are required as sample nodes in quasi-Monte Carlo algorithms, which are deterministic variants of Monte Carlo rules for numerical integration. Since its introduction many people have studied the van der Corput sequence and generalizations thereof. This led to a huge number of results. On the occasion of the 125th birthday of J.G. van der Corput we survey many interesting results on van der Corput sequences and their generalizations. In this way we move from van der Corput’s ideas to the most modern constructions of sequences for quasi-Monte Carlo rules, such as, e.g., generalized Halton sequences or Niederreiter’s ( t , s ) -sequences.

International audience; We give an exact formula for the $L_2$ discrepancy of a class of generalized two-dimensional Hammersley point sets in base $b$, namely generalized Zaremba point sets. These point sets are digitally shifted Hammersley point sets with an arbitrary number of different digital shifts in base $b$. The Zaremba point set introduced by White in 1975 is the special case where the $b$ shifts are taken repeatedly in sequential order, hence needing at least $b^b$ points to obtain the optimal order of $L_2$ discrepancy. On the contrary, our study shows that only one non-zero shift is enough for the same purpose, whatever the base $b$ is.

With the development of unmanned aerial vehicles (UAVs) and global navigation satellite system (GNSS), the accurate camera positions at exposure can be known and the GNSS-assisted bundle block adjustment (BBA) approach is possible for integrated sensor orientation (ISO). This study employed ISO approach for camera pose determination with the objective of investigating the impact of a good sensor pre-calibration on a poor acquisition geometry. Within the presented works, several flights were conducted on a dike by a small UAV embedded with a metric camera and a GNSS receiver. The multi-lever-arm estimation within the BBA procedure makes it possible to merge image blocks of different configurations such as nadir and oblique images without physical constraints on camera and GNSS antenna positions. The merged image block achieves a better accuracy and the sensor self-calibrated well. The issued sensor calibration is then applied to a less preferable acquisition configuration and the accuracy is significantly improved. For a corridor acquisition scene of about 600 m , a centimetric accuracy is reached with one GCP. With the provided sensor pre-calibration, an accuracy of 3.9 c m is achieved without any GCP.

International audience; Unfavorable erosion to a revetment can affect the stability of the bank and may jeopardize the safety of adjacent structures, thus improvement work is needed to increase the stability of the revetment as well as reducing the possibility of failure. The use of geotextiles as a protection material for banks is not only environmentally friendly, but also stable in the long run. However, improper design of geotextiles may cause considerable loss of soil, which might result in failure. The actual flow behavior in revetments using geotextiles is rather complicated and can be categorized into three zones, namely, the uni-directional flow zone, the cyclic flow zone, and the tangential flow zone. In this study, a wave flume experiment was performed on model revetments using two kinds of geotextiles as the filter material to prevent erosion induced by cyclic flows. Soil migration behaviors were monitored. Furthermore, two kinds of cover blocks, riprap and concrete blocks, were carefully placed on the revetments in order to avoid puncture and abrasion of geotextiles during construction of revetments. The main purpose of this study is to elucidate the erosion control and filtration performance of soil-geotextile filtration systems under wave action. Two nonwoven needle punched geotextiles were tested. The geotextiles both have the same characteristic opening size, but have a different number of constrictions and different structures. One is a thin double-layer nonwoven material consisting of continuous filaments and the other is a thick one-layer nonwoven material consisting of short fibers. The test result reveals that two different erosion mechanisms occur during wave action. The cyclic wave loadings triggered higher excess pore-water pressure in the upper part of the model and resulted in soil collapse. The geotextile with a higher number of constrictions produced more serious collapse than that with a lower one. At the middle part of the revetments, soil was eroded by the up-and-down drag force of the flow along the bank. In this zone, the thick geotextile displayed better performance in retarding the drag force on the soil surface. In addition, the opening size and thickness of the geotextile as well as the coverage condition provided by the geotextile were the key factors controlling soil erosion.

The L2 discrepancy is a quantitative measure for the irregularity of distribution of a finite point set. In this paper we consider the L2 discrepancy of so-called generalized Hammersley point sets which can be obtained from the classical Hammersley point sets by introducing some permutations on the base b digits. While for the classical Hammersley point set it is not possible to achieve the optimal order of L2 discrepancy with respect to a general lower bound due to Roth this disadvantage can be overcome with the generalized version thereof. For special permutations we obtain an exact formula for the L2 discrepancy from which we obtain two-dimensional finite point sets with the lowest value of L2 discrepancy known so far. AMS subject classification: 11K06, 11K38.

Halton sequences have always been quite popular with practitioners, in part because of their intuitive definition and ease of implementation. However, in their original form, these sequences have also been known for their inadequacy to integrate functions in moderate to large dimensions, in which case ( t , s )-sequences such as the Sobol' sequence are usually preferred. To overcome this problem, one possible approach is to include permutations in the definition of Halton sequences—thereby obtaining generalized Halton sequences —an idea that goes back to almost thirty years ago, and that has been studied by many researchers in the last few years. In parallel to these efforts, an important improvement in the upper bounds for the discrepancy of Halton sequences has been made by Atanassov in 2004. Together, these two lines of research have revived the interest in Halton sequences. In this article, we review different generalized Halton sequences that have been proposed recently, and compare them by means of numerical experiments. We also propose a new generalized Halton sequence which, we believe, offers a practical advantage over the surveyed constructions, and that should be of interest to practitioners.

We determine the Lp discrepancy of the two-dimensional Hammersley point set in base b. These formulas show that the Lp discrepancy of the Hammersley point set is not of best possible order with respect to the general (best possible) lower bound on Lp discrepancies due to Roth and Schmidt. To overcome this disadvantage we introduce permutations in the construction of the Hammersley point set and show that there always exist permutations such that the Lp discrepancy of the generalized Hammersley point set is of best possible order. For the L2 discrepancy such permutations are given explicitly.

Increased fruit and vegetable consumption has become a health priority in many countries. Therefore, data investigating the influence of different types of fruits and vegetables on serum antioxidant levels would be useful. The objective of the study was to assess the relationship between fruit and vegetable consumption and vitamin serum antioxidant concentrations. Specific fruit and vegetable groups are evaluated. A total of 3521 subjects (1487 men and 2034 women), aged 35-60 years, participating in the SU.VI.MAX cohort were included in this study. Blood samples of participants were analysed for beta-carotene, vitamin C and alpha-tocopherol. Each subject had completed at least six dietary records during the first 2 years of the study. It was found that women had higher mean beta-carotene and vitamin C serum concentrations than men, but lower alpha-tocopherol serum concentrations. Serum beta-carotene and vitamin C concentrations were positively correlated with consumption of both fruit and vegetables, as well as with most of the fruit and vegetable groups tested. These relationships persisted after adjustment for confounding factors. Regression analysis showed a linear dose-response relationship. Root vegetables and citrus fruits were particularly associated with beta-carotene serum status as were citrus fruits for vitamin C. Fruit and vegetable consumption was either not or weakly associated with alpha-tocopherol serum concentrations. These results describe antioxidant serum concentrations according to fruit and vegetable consumption in a large sample and support the findings of previous studies involving a more limited number of subjects.

Several studies have demonstrated beneficial effects of supplemental trivalent Cr in subjects with reduced insulin sensitivity with no documented signs of toxicity. However, recent studies have questioned the safety of supplemental trivalent Cr complexes. The objective of this study was to evaluate the cytotoxic and genotoxic potential of the Cr(III) complexes (histidinate, picolinate, and chloride) used as nutrient supplements compared with Cr(VI) dichromate. The cytotoxic and genotoxic effects of the Cr complexes were assessed in human HaCaT keratinocytes. The concentrations of Cr required to decrease cell viability were assessed by determining the ability of a keratinocyte cell line (HaCaT) to reduce tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. DNA damage using the Comet assay and the production of 8-hydroxy-2'-deoxyguanosine were also determined with and without hydrogen peroxide-induced stress. The LC50 for human cultured HaCaT keratinocytes was 50 microM for hexavalent sodium dichromate and more than 120-fold higher for Cr chloride (6 mM) and Cr histidinate (10 mM). For Cr picolinate at saturating concentration (120 microM) the LC50 was not attained. High Cr(III) concentrations, 250 microM Cr as Cr chloride and Cr histidinate and 120 microM Cr picolinate (highest amount soluble in the system), not only did not result in oxidative DNA damage but exhibited protective antioxidant effects when cells were exposed to hydrogen peroxide-induced oxidative stress. These data further support the low toxicity of trivalent Cr complexes used in nutrient supplements.

We investigated the effect of a moderate mutivitamin and mineral supplementation containing mainly vitamin C (150.0 mg.day(-1)), vitamin E (24.0 mg.day(-1)) and beta-carotene (4.8 mg.day(-1)) prior to and during an extreme running competition -the Marathon des Sables (MDS)- that consisted of six long races in the desert.Seventeen athletes participated in our double blind, placebo-controlled study. Blood samples were collected prior to the supplementation i.e. three weeks before the competition (D-21), two days prior to the MDS (D-2), after the third race (D3) and at the end of the competition (D7). Erythrocyte antioxidant enzyme activity (glutathione peroxidase (GPx), superoxide dismutase (SOD)), erythrocyte glutathione level (GSH), plasma non-enzymatic antioxidant status (uric acid, vitamin C, alpha-tocopherol, retinol, beta-carotene), markers of plasma lipid peroxidation (thiobarbituric reactive substances (TBARS)), reactive carbonyl derivatives (RCD) and membrane damage (creatine kinase and lactate dehydrogenase activities) were measured.In both groups, GSH levels, uric acid levels and membrane damage significantly increased during the competition while SOD activity significantly decreased. In Supplemented group, plasma alpha-tocopherol, beta-carotene and retinol levels significantly increased after three weeks of supplementing. In contrast to Placebo group, alpha-tocopherol, vitamin C and retinol levels were significantly affected by the competition in Supplemented group. Moreover, no increase in TBARS was observed in Supplemented group during the competition, whereas TBARS significantly increased at D3 in the placebo group.The moderate multivitamin-mineral supplementation prevented the transient increase in TBARS levels during this extreme competition.

International audience; The class of $(t,m,s)$-nets and $(t,s)$-sequences, introduced in their most general form by Niederreiter, are important examples of point sets and sequences that are commonly used in quasi-Monte Carlo algorithms for integration and approximation. Low-dimensional versions of $(t,m,s)$-nets and $(t,s)$-sequences, such as Hammersley point sets and van der Corput sequences, form important sub-classes, as they are interesting mathematical objects from a theoretical point of view, and simultaneously serve as examples that make it easier to understand the structural properties of $(t,m,s)$-nets and $(t,s)$-sequences in arbitrary dimension. For these reasons, a considerable number of papers have been written on the properties of low-dimensional nets and sequences.

To assess relationships between energy, nutrient and food intakes, alcohol consumption, smoking status and body mass index (BMI), and serum concentrations of beta-carotene, alpha-tocopherol, vitamin C, selenium and zinc.Data on health status, alcohol consumption, smoking habits, anthropometric data and biochemical measurements were obtained in 1821 women aged 35-60 y and 1307 men aged 45-60 y, participant to the SU.VI.MAX Study. Data on dietary intake were available on a subsample who reported six 24-h dietary records during the first 18 months of the study.Women had higher baseline serum beta-carotene and vitamin C concentrations and lower concentration for serum vitamin E, zinc and selenium than men. In women, younger age was associated with lowered mean concentration of serum beta-carotene, vitamin E and selenium. In men, only differences were observed for serum zinc, which was lower in older men. Current smokers of both sexes had significantly lower concentrations of serum beta-carotene, vitamin C and selenium, and, only in women, of vitamin E, than nonsmokers. Alcohol consumers had lower concentrations of serum beta-carotene and higher selenium concentrations. Serum beta-carotene and vitamin C concentrations were lower in obese subjects. There were positive associations of dietary beta-carotene, vitamin C and E with their serum concentrations. Age, nutrient and alcohol intakes, serum cholesterol, BMI and smoking status explained 15.2% of the variance of serum beta-carotene in men and 13.9% in women, and 10.8 and 10.0% for serum vitamin C, and 26.3 and 28.6% for serum vitamin E, respectively.Serum antioxidant nutrient concentrations are primarily influenced by sex, age, obesity, tobacco smoking, alcohol consumption and especially dietary intake of those antioxidant nutrients.

International audience; The aim of this survey paper is to give an updated overview of results on low dis- crepancy sequences obtained via Atanassov’s methods. These methods first initiated for Halton sequences have been later on extended to generalizations of these sequences and to (t, s)- sequences, the other well known family of low discrepancy sequences, including polynomial arithmetic analogues of Halton sequences.

In the first part of this paper, after a survey on the general theory of (t, s)-sequences, we review the main constructions of (0, s)-sequences and point out some relations between them. From these comparisons and from examples we have met in another context, we have found new (0, s)-sequences in prime base b to which the second part is devoted; the proofs are based on the general framework of formal Laurent series introduced by Niederreiter; the construction can be randomized and should have numerical applications.

Selenium is an essential trace element which is part of the active site of seleno-dependent glutathione peroxidase and type 1 deiodinase. Therefore, it plays a key role in thyroid hormone metabolism. The present work was undertaken in order to evaluate selenium status in two Ivory Coast populations: the first with high (Glanlé) and the second with low (Abidjan) prevalence of iodine deficiency. Selenium, glutathione peroxidase, glutathione reductase, glutathione and diglutathione were determined in blood and/or urine. In plasma and erythrocytes, selenium and glutathione peroxidase were dramatically low in Glanlé. Compared to Abidjan, selenium, glutathione peroxidase, vitamin E and riboflavin status were decreased whereas diglutathione was increased in Glanlé. The results clearly demonstrate a selenium deficiency and suggest an oxidant stress in Glanlé. Causes and consequences of this selenium deficiency and oxidant stress remain to be determined.

Let \(\) be the binomial coefficient modulo b (b prime), with \(\) if l is greater than c, and let \(\) be the sum of binomial coefficients modulo b, that is \(\) (mod b). We prove the following property: the \(\) for which the couples c, l verify \(\) and \(\) are uniformly distributed in the residue classes modulo b as n tends to infinity. The method, using the Perron-Frobenius theory, applies also to \(\) and gives a new proof of the well known result for the non-zero binomial coefficients modulo b.

The "SUpplementation en VItamines et Mineraux AntioXydants" (SU.VI.MAX) Study is a randomized double-blind, placebo-controlled, primary-prevention trial which started in 1994 in France. This epidemiologic study is designed to test the efficacy of a daily supplementation with antioxidant vitamins (vitamin C, 120 mg, vitamin E, 30 mg, and beta-carotene, 6 mg) and minerals (selenium, 100 microg, and zinc, 20 mg) at nutritional doses, in reducing the main causes of premature death (cancers and cardiovascular diseases); 12,735 eligible subjects (women aged 35 to 60 years, and men aged 45 to 60 years) were included in 1994 and and will be followed up for 8 years. Participants undergo a yearly visit consisting, every other year, of either biological sampling or clinical examination. They also regularly provide information on health events and dietary intake by filling out computerized questionnaires using the Minitel Telematic Network. After 2 years of supplementation, biochemical indicators of vitamin and trace element status reach reasonable level without reaching concentrations as high as those observed in intervention studies, which tested relatively high doses of antioxidants, and ended up with higher risk of pathology.

Cigarette smoke is known to generate free radicals by various mechanisms. In this study involving 30 non-smokers and 30 smokers, we show that urinary excretion of 5-(hydroxymethyl) uracil (HMUra) was not different in the two groups (6.54+/-2.07 vs. 6.70+/-1.68 nmol/mmol creatinine). In contrast, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo) excretion increased by 16% (1.16+/-0.35 vs. 1.35+/-0.50 nmol/mmol creatinine, p = 0.039). Results concerning 8-oxo-dGuo are in agreement with those of previous studies. We observed significant multiple correlations between HMUra and creatinine (r(p) = 0.44), BMI (r(p) = -0.27) and nicotine derivatives (r(p) = 0.26). Multiple correlation analysis showed relations between 8-oxo-dGuo on the one hand, and: creatinine (r(p) = 0.36), nicotine derivatives (r(p) = 0.29), BMI (r(p) = -0.24) on the other.

We measured the base 5-(hydroxymethyl) uracil (HMUra) and the nucleoside 8-oxo-7,8-dehydro-2'-deoxyguanosine (8-oxo-dGuo) in urine of adriamycin-treated cancer patients. Adriamycin has been shown to generate oxygen free radicals by various mechanisms. HMUra and 8-oxo-dGuo are two known lesions of DNA, produced by oxygen free reaction on thymine and 2'-deoxyguanosine, respectively. HMUra was measured by GC-MS/isotopic dilution and 8-oxo-dGuo by HPLC/EC, both after prepurification by semipreparative HPLC. Here we report the results of a study involving 20 cancer patients treated with flash doses of ADR. We found that urine HMUra is significantly increased (HMUra (nmol/24h): 80.8 8.44 vs. 98.7+/-6.87; p < 0.01) 24h after administration of the drug, while 8-oxo-dGuo did not show any significant variation. Urine HMUra seems to be a suitable short-term marker of DNA alterations by oxygen free radicals.

International audience; In this paper, we derive new general upper bounds on the star discrepancy of (t,m,s)-nets and (t,s)-sequences. These kinds of point sets are among the most widely used in quasi-Monte Carlo methods for numerical integration. By our new results, we improve on previous discrepancy bounds and prove a conjecture stated by the second author in an earlier paper.

Pour connaitre la debitance de ses barrages, la Compagnie Nationale du Rhone calcule les debits par une equation de debitance. Celle-ci est specifique au type de vannes de l’ouvrage et est determinee par des essais realises sur modele physique au 1/35eme . Le coefficient de debitance est modelise pour chaque vanne par une equation unique, qui est ensuite implementee dans l’automate de calcul du debit de l’ouvrage. L’objectif de l’etude est de quantifier les incertitudes associees au debit calcule sur l’ouvrage et de hierarchiser les composantes d’incertitude afin d’identifier les ameliorations a engager. L’estimation de l’incertitude est realisee par application de la loi de composition des incertitudes-types et comparee aux resultats des propagations des densites de probabilite par simulations de Monte-Carlo. Le domaine d’interet comprend de multiples valeurs des variables principales (hauteurs d’eau en amont et en aval, ouverture de la vanne, etc.), avec quatre regimes d’ecoulement. Pour 92,5 % des 50 000 configurations traitees, l’ecart entre les deux methodes est inferieur a 1 % ; les autres configurations, presentant des ecarts plus importants, correspondent a un regime d’ecoulement particulier dont l’equation est fortement non lineaire. L’etude montre les specificites et difficultes de l’estimation des incertitudes par les methodes de composition des incertitudes-types et par Monte-Carlo pour un domaine d’interet etendu, tant au niveau des calculs qu’au niveau de l’interpretation des resultats.

Contact erosion is potentially initiated at the interface between two soil layers by a groundwater flow within the coarser material. Once eroded by the flow, particles from the finer soil are transported through the pores of the coarser layer. Fluvial dikes are often exposed to this phenomenon. Small-scale experiments combining refractive index matching medium, planar laser-induced fluorescence, and particle image velocimetry were carried out to measure the flow characteristics in the vicinity of an interface between a model granular medium and a fine graded sandy layer. Longitudinal velocities and shear-stress distributions were obtained in Darcy flow conditions. They revealed a long tail toward large values, which reflects the spatial variability of the constrictions in the pores network. Taking into account these distributions can improve the modelling of contact erosion by going beyond the simple use of mean quantities, like Darcy velocity, as is usually proposed in the literature. This is done by successively considering the variability of the porous flow and also that of the critical shear stress. As a main consequence, the resulting global erosion rate is nownonzero for any value of the mean shear stress and there is no longer a stress threshold. Finally, the effect of paving at the sand surface can also be added to the statistical model and makes it possible to account very satisfactorily for previous contact erosion tests at the sample scale.

International audience

Resume Introduction. – Une etude recente (Groussard et al., communication personnelle) a montre qu'un exercice de sprint isole (30 s) s'accompagne d'une surproduction de radicaux lipidiques et d'une alteration du systeme enzymatique antioxydant sanguin. Ce meme exercice pourrait egalement affecter le statut antioxydant non-enzymatique plasmatique. Synthese des faits. – Huit etudiants en APS, ont realise une epreuve de Wingate. Le statut antioxydant non-enzymatique plasmatique (acide urique, vitamines C et E, β-carotene) a ete evalue au repos (R), a l'arret de l'echauffement (E) a l'arret du test (P0), puis a 5 (P5), 10 (P10), 20 (P20) et 40 (P40) minutes de recuperation. L'exercice de Wingate s'accompagne d'une augmentation de l'acide urique et de la vitamine C respectivement a partir de P10 et P20. A l'inverse, la concentration en vitamine E diminue a P5–P10 puis remonte aux valeurs basales, tandis que le β-carotene chute des P5. Conclusion. – Les resultats demontrent qu'un exercice de sprint isole de 30 s altere egalement le statut antioxydant plasmatique non-enzymatique.