Non-negative Independent Component Analysis Algorithm Based on 2D Givens Rotations and a Newton Optimization

ISBN 978-3-642-15994-7, SoftcoverInternational audienceIn this paper, we consider the Independent Component Analysis problem when the hidden sources are non-negative (Non-negative ICA). This problem is formulated as a non-linear cost function optimization over the special orthogonal matrix group SO(n). Using Givens rotations and Newton optimization, we developed an effective axis pair rotation method for Non-negative ICA. The performance of the proposed method is compared to those designed by Plumbley and simulations on synthetic data show the efficiency of the proposed algorithm

Analyse comparative, physiologique et moléculaire des effets de trois traitements masculinisants chez le tilapia du Nil, Oreochromis niloticus, et recherche de marqueurs de traçabilité liés à ces approches

Due to the genuine advantages of this species (fast growth, spontaneous breeding in captivity), the aquaculture production of tilapias, and especially of the Nile tilapia Oreochromis niloticus (L.), has been growing steadily over the past 30 years. Nevertheless, the success of this production is largely dependent on the sex control efficiency, in order to take advantage of the better growth of males and to avoid uncontrolled breeding that can cause crowding and dwarfism. The use of male monosex populations has thus become a standard in tilapia aquaculture since the 1970s. The dietary administration of 17α-methyltestosterone (17MT) is still the major masculinising procedure used in tilapia farming nowadays. However, it raises issues concerning the environment, fish farmers and consumers'health. More recently, alternatives to hormonal sex reversal have been evaluated, i.e. the use of YY males, treatment using aromatase inhibitors or elevated temperatures during the early life stages. In the present study, the effects of fadrozole (an aromatase inhibitor), elevated temperatures and 17MT have been compared on the survival and growth of XX fish, and as regards to the expression patterns in the brain and gonads of key genes implicated in fish sex differentiation. Comparisons seen in these induced-males were performed with genetic XX females and XY males. The growth rates of fish raised at elevated temperature were similar to those of genetic males, thereby emphasizing the relevance of this method as an alternative to hormonal sex reversal of Nile tilapia, when using highly thermosensitive strains. Whether the growth of tilapia is stimulated by androgens or depressed by estrogens is discussed. The analysis of expression profiles of the genes involved in sexual differentiation reveals different patterns in the brain and in the gonads. Amh and cyp19a1b are strongly stimulated in the brain of XX neomales treated by elevated temperatures. Conversely, amh is inhibited in the brain of fish treated with fadrozole, suggesting that amh is directed or indirectly regulated by aromatase. In the gonads of XX neomales, the levels of dmrt1 and amh are much higher than in genetic XY males. Further studies should analyse a) the fertility of neomales, b) the plasmatic levels of steroids and proteins, c) the histology and immunohistochemistry of the brain and the gonads, and d) the expression of other genes.Keywords : Nile tilapia / Masculinisation / Temperature / Hormones / Growth / GenesLa production de tilapias et surtout celle du tilapia du Nil Oreochromis niloticus (Linnaeus, 1758) connaît depuis 30 ans, une impressionnante croissance liée à ses nombreux atouts pour l'aquaculture. Toutefois, le contrôle du sexe conditionne la rentabilité de cette filière. En effet chez le tilapia du Nil le mâle présente une meilleure croissance que la femelle. Depuis les années 70, la production de populations monosexes mâles de tilapia du Nil est pratiquée dans la quasi-totalité des fermes aquacoles afin de bénéficier de la meilleure croissance des mâles par rapport aux femelles et de contrôler la reproduction précoce et continue chez cette espèce. Actuellement, l'inversion hormonale du sexe par la 17α-methyltestosterone (17MT) constitue la technique la plus utilisée pour produire les cohortes monosexes mâles. Toutefois, l'utilisation des hormones pour la production de poissons marchands soulève de nombreuses questions relevant de la sécurité alimentaire comme de la protection des travailleurs piscicoles et de l'environnement. D'autres approches sont donc recherchées. Elles reposent sur des approches génétiques, ou sur les effets masculinisants des fortes températures ou enfin sur l'utilisation d'anti-aromatase. Dans cette thèse, nous avons comparé les effets de trois traitements, utilisant respectivement la 17MT, le fadrozole (un inhibiteur de l'aromatase) et les fortes températures, sur des caractères d'intérêt zootechniques (survie, croissance) et sur l'expression de gènes clés de la différenciation du sexe dans les gonades et dans le cerveau des mâles induits (mâles 17MT, mâles anti-aromatase et thermo-néomâles). Parallèlement les mêmes analyses ont été menées sur des mâles et des femelles génétiques. Les fortes températures produisent des mâles dont la croissance est similaire à celle des mâles génétiques, confortant l'idée que les traitements thermiques pourraient constituer une alternative écologique aux utilisations des hormones pour la production de populations monosexes mâles chez le tilapia, sous réserve de sélectionner des souches à forte thermosensibilité. Le rôle positif des androgènes et/ou l'effet inhibiteur des œstrogènes sur la croissance est discuté. L'analyse des profils d'expression de gènes clés de la différenciation sexuelle suggère des régulations différentes dans le cerveau et dans les gonades. En particulier, l'amh et cyp19a1b sont très fortement stimulées dans le cerveau des mâles traités par la température ; inversement l'amh est inhibée dans le cerveau des individus traités par le fadrozole, suggérant une régulation directe ou indirecte de l'amh par l'aromatase. Dans les gonades des mâles induits, les niveaux de dmrt1 et amh sont surexprimés par rapport à ce qui est observé chez les mâles génétiques. Ce travail mériterait d'être complété par a) des études sur la fertilité des mâles induits b) des dosages des taux circulants de stéroïdes et de protéines dans le plasma c) des analyses histologiques ou immunohistochimiques du cerveau et des gonades et d) l'étude de l'expression d'autres gènes.Mots-clés : Tilapia du Nil / Masculinisation / Température / Hormones / Croissance / Gène

Geometrical Method Using Simplicial Cones for Overdetermined Nonnegative Blind Source Separation: Application to Real PET Images

International audienceThis paper presents a geometrical method for solving the overdetermined Nonnegative Blind Source Separation (N-BSS) problem. Considering each column of the mixed data as a point in the data space, we develop a Simplicial Cone Shrinking Algorithm for Unmixing Nonnegative Sources (SCSA-UNS). The proposed method estimates the mixing matrix and the sources by fitting a simplicial cone to the scatter plot of the mixed data. It requires weak assumption on the sources distribution, in particular the independence of the different sources is not necessary. Simulations on synthetic data show that SCSA-UNS outperforms other existing geometrical methods in noiseless case. Experiment on real Dynamic Positon Emission Tomography (PET) images illustrates the efficiency of the proposed method

Regularized Gradient Algorithm for Non-Negative Independent Component Analysis

International audienceIndependent Component Analysis (ICA) is a well-known technique for solving blind source separation (BSS) problem. However "classical" ICA algorithms seem not suited for non-negative sources. This paper proposes a gradient descent approach for solving the Non- Negative Independent Component Analysis problem (NNICA). NNICA original separation criterion contains the discontinuous sign function whose minimization may lead to ill convergence (local minima) especially for sparse sources. Replacing the discontinuous function by a continuous one tanh, we propose a more accurate regularized Gradient algorithm called "Exact" Regularized Gradient (ERG) for NNICA. Experiments on synthetic data with different sparsity degrees illustrate the efficiency of the proposed method and a comparison shows that the proposed ERG outperforms existing methods

On the Suppression of Noise from a Fast Moving Acoustic Source using Multimodality

International audienceThe problem of cancelling the noise from a moving acoustic source in outdoor environment is investigated in this paper. By making use of the known instantaneous location of the moving source (provided by a second modality), we propose a time-domain method for removing the noise from a moving source in a mixture of acoustic sources. The proposed method consists in resampling the mixed data recorded at a reference sensor, and by linearly combining the resampled data and the non-resampled data of the others sensor to cancel the undesired source. Simulation on synthetic data show the effectiveness and the usefulness of the proposed method

Non-Negative Blind Source Separation Algorithm Based on Minimum Aperture Simplicial Cone

International audienceWe address the problem of Blind Source Separation (BSS) when the hidden sources are Nonnegative (N-BSS). In this case, the scatter plot of the mixed data is contained within the simplicial cone generated by the columns of the mixing matrix. The proposed method, termed SCSA-UNS for Simplicial Cone Shrinking Algorithm for Unmixing Non-negative Sources, aims at estimating the mixing matrix and the sources by fitting a Minimum Aperture Simplicial Cone (MASC) to the cloud of mixed data points. SCSA-UNS is evaluated on both independent and correlated synthetic data and compared to other N-BSS methods. Simulations are also performed on real Liquid Chromatography-Mass Spectrum (LC-MS) data for the metabolomic analysis of a chemical sample, and on real dynamic Positron Emission Tomography (PET) images, in order to study the pharmacokinetics of the [18F]-FDG (FluoroDeoxyGlucose) tracer in the brain

Assessing the competitive ability of the invader Senna obtusifolia with coexisting natives species under different water stress regimes

Invasive species tend to pose a threat to ecosystem biodiversity, functioning, and ecosystem service provision. This study was conducted in Burkina Faso to assess the competitiveness of an invasive species Senna obtusifolia that is a less palatable legume plant in West African Sahelian rangelands. To address the research hypothesis that the recurrent drought in the Sahel results in S. obtusifolia being more competitive in the land invasion, we conducted an interspecific competition involving S. obtusifolia and 3 herbaceous species (Andropogon gayanus, Chamaecrista mimosoides, and Pennisetum pedicellatum) in a greenhouse experiment under four water stress regimes using a replacement series design. The height and biomass of each species were measured throughout four months experiment. In the severe water regime, S. obtusifolia was the most sensitive to water deficit while the 3 other species were found to be resistant. In addition, in all water regimes, the aggressivity index revealed that S. obtusifolia was less competitive than the grass species A. gayanus and P. pedicellatum. Further, the study discovered that drought in the Sahel made S. obtusifolia more vulnerable than the other species. Hence the invasion of Sahelian rangelands by S. obtusifolia could be favored by overgrazing that reduces fodder species' dominance and competitiveness. Good management of sahelian rangelands by controlling grazing could help to reduce S. obtusifolia invasion and provide more fodder for livestock

Feeding behaviors during home-based treatment of moderate acute malnutrition using corn-soy blends or lipid-based nutrient supplements.

Feeding behaviors have an important impact on children's nutritional status and are essential to consider when implementing nutrition programs. The objective of this study was to explore and compare feeding behaviors related to supplementary feeding with corn-soy blends (CSB) and lipid-based nutrient supplements (LNS) based on best practice feeding behaviors. The study was conducted as part of a randomized controlled trial assessing the effectiveness of new formulations of CSB and LNS and comprised 1,546 children from 6 to 23 months. The study included a mixed methods approach using questionnaires, focus group discussions and home visits and interviews with a subsample of 20 caretakers of trial participants. We found that LNS, compared to CSB, were more likely to be mixed into other foods (OR [95% CI] 1.7 [1.3-2.2], p = <.001), served with a meal (OR [95% CI] 1.6 [1.1-2.3], p = <.018)or between meals (OR [95% CI] 1.5 [1.1-1.9], p = <.005), and fed using an encouraging feeding style (mean difference in percentage points [95% CI] 23% [6%:40%], p = .01). CSB were more likely to be fed using a forced feeding style (mean difference in percentage points [95% CI] 18% [3%:33%], p = .02) and were often observed to be served unprepared. The main differences in feeding behaviors between the two diet groups were linked to how and when supplements were served. Educational instructions should therefore be adapted according to the supplement provided; when providing CSB, efforts should be made to promote an encouraging feeding style, and emphasis should be made to ensure preparations are made according to recommendations

Artemether-lumefantrine versus amodiaquine plus sulfadoxine-pyrimethamine for uncomplicated falciparum malaria in Burkina Faso: a randomised non-inferiority trial.

BACKGROUND: Artemisinin-based combination regimens are widely advocated for malarial treatment, but other effective regimens might be cheaper and more readily available. Our aim was to compare the risk of recurrent parasitaemia in patients given artemether-lumefantrine with that in those given amodiaquine plus sulfadoxine-pyrimethamine for uncomplicated malaria. METHODS: We enrolled 521 patients aged 6 months or older with uncomplicated falciparum malaria in Bobo-Dioulasso, Burkina Faso. Patients were randomly assigned to receive standard doses of either artemether-lumefantrine (261) or amodiaquine plus sulfadoxine-pyrimethamine (260) for 3 days. Primary endpoints were the risks of treatment failure within 28 days, either unadjusted or adjusted by genotyping to distinguish recrudescence from new infection. The study is registered at controlled-trials.gov with the identifier ISRCTN54261005. FINDINGS: Of enrolled patients, 478 (92%) completed the 28-day study. The risk of recurrent symptomatic malaria was lowest in the group given amodiaquine plus sulfadoxine-pyrimethamine (1.7%vs 10.2%; risk difference 8.5%; 95% CI 4.3-12.6; p=0.0001); as was the risk of recurrent parasitaemia (4.7%vs 15.1%; 10.4%; 5.1-15.6; p=0.0002). Nearly all recurrences were due to new infections. Recrudescences were four late treatment failures with artemether-lumefantrine and one early treatment failure with amodiaquine plus sulfadoxine-pyrimethamine. Both regimens were safe and well tolerated, with pruritus more common with amodiaquine plus sulfadoxine-pyrimethamine than with artemether-lumefantrine. Each regimen selected for new isolates with mutations that have been associated with decreased drug susceptibility. INTERPRETATION: Amodiaquine plus sulfadoxine-pyrimethamine was more effective than was artemether-lumefantrine for the treatment of uncomplicated malaria. For regions of Africa where amodiaquine plus sulfadoxine-pyrimethamine continues to be effective, this less expensive and more available regimen should be considered as an alternative to blanket recommendations for artemisinin-based combination treatment for malaria