Rémi Servien

• PhD
• Researcher at French National Institute for Agriculture, Food, and Environment (INRAE)

Background Metabolomics describes the metabolic profile of an organism at a given time by the concentrations of its constituent metabolites. When studied over time, metabolite concentrations can help understand the dynamical evolution of a biological process. However, metabolites are involved into sequences of chemical reactions, called metabolic p...

Capturing produced, consumed, or exchanged metabolites (metabolomics) and the result of gene expression (transcriptomics) require the extraction of metabolites and RNA. Multi-omics approaches and, notably, the combination of metabolomics and transcriptomic analyses are required for understanding the functional changes and adaptation of microorganis...

In this article, we focus on the problem of variable selection in a functional regression framework. This question is motivated by practical applications in the field of agronomy: In this field, identifying the temporal periods during which weather measurements have the greatest impact on yield is critical for guiding agriculture practices in a cha...

During wastewater treatment, micropollutants are only partly eliminated and may present a risk for human health and aquatic ecosystems. The potential impacts these substances may have are currently underestimated due to the lack in available concentrations that lie below the limit of quantification (LOQ) for an important set of micropollutants. Her...

Together with environmental factors, physiological maturity at birth is a major determinant for neonatal survival and postnatal development in mammalian species. Maturity at birth is the outcome of complex mechanisms of intra-uterine development and maturation during the end of gestation. In pig production, piglet preweaning mortality averages 20%...

Full-text available at https://hal.inrae.fr/LBE/hal-03856941v1

The quantitative structure activity relationship (QSAR) methodology has been developed and extensively used to predict unknown environmental data for compounds that have not been experimentally studied yet. QSAR is based on a large series of descriptors: such as the number of atoms, the number of bonds… (descriptive), or based on the 2D structure o...

Biathlon is an Olympic sport combining cross-country skiing with rifle shooting, giving a penalty for each target miss. The biathletes ran different race formats, including the pursuit race. During this race, the biathletes chase the leader with a start time identical to the result of the sprint race previously achieved. So, pursuit involves differ...

Peer Community Journal It is a real challenge for life cycle assessment practitioners to identify all relevant substances contributing to ecotoxicity. Once this identification has been made, the lack of corresponding ecotoxicity factors can make the results partial and difficult to interpret. So, it is a real and important challenge to provide eco...

During wastewater treatment, incomplete elimination of micropollutants occurs. Recently, the potential impacts of the release of some micropollutants at the scale of France have been studied. These impacts calculations were incomplete due to a lack of characterization factors. In the present study, we used already developed machine learning models...

It is a real challenge for life cycle assessment practitioners to identify all relevant substances contributing to the ecotoxicity. Once this identification has been made, the lack of corresponding ecotoxicity factors can make the results partial and difficult to interpret. So, it is a real and important challenge to provide ecotoxicity factors for...

Following treatment, amounts of pesticides can reach the atmosphere because of spray drift, volatilization from soil or plants, and/or wind erosion. Monitoring and risk assessment of air contamination by pesticides is a recent issue and more insights on pesticide transfer to atmosphere are needed. Thus, the objective of this work was to better unde...

Metabolomics is a promising approach to characterize phenotypes or to identify biomarkers. It is also easily accessible through NMR, which can provide a comprehensive understanding of the metabolome of any living organisms. However, the analysis of 1H NMR spectrum remains difficult, mainly due to the different problems encountered to perform automa...

In mammalian species, the first days after birth are an important period for survival and the mortality rate is high before weaning. In pigs, perinatal deaths average 20% of the litter, with important economic and societal consequences. Maturity is one of the most important factors that influence piglet survival at birth. Maturity can be defined as...

Metabolomics is a promising approach to characterize phenotypes or to identify biomarkers. It is also easily accessible through NMR, which can provide a comprehensive understanding of the metabolome of any living organisms. However, the analysis of ¹ H NMR spectrum remains difficult, mainly due to the different problems encountered to perform autom...

In mammalian species, the first days after birth are an important period for survival and the rates of mortality before weaning are high. In pigs, the perinatal deaths average 20% of the litter, with important economic and societal consequences. Among the factors influencing piglet survival at birth, the maturity is likely to be one of the most imp...

We study the LASSO and SLOPE estimators when the design X satisfies ker⁡(X)=0. Similarly to the LASSO, the SLOPE estimator has an explicit expression when the design matrix X is orthogonal which is reported in the main theorem of this article. We state that, even if the design is not orthogonal, even if residuals are correlated, up to a transformat...

The asymptotic behavior of a plug-in kernel estimator of the regression level sets is studied. The exact asymptotic limit of the symmetric difference is derived for a given level and for an unknown level corresponding to a fixed probability.

Motivation: In metabolomics, the detection of new biomarkers from Nuclear Magnetic Resonance (NMR) spectra is a promising approach. However, this analysis remains difficult due to the lack of a whole workflow that handles spectra pre-processing, automatic identification and quantification of metabolites and statistical analyses, in a reproducible...

This work focuses on the issue of variable selection in functional regression. Unlike most work in this framework, our approach does not select isolated points in the definition domain of the predictors, nor does it rely on the expansion of the predictors in a given functional basis. It provides an approach to select full intervals made of consecut...

Les dispositifs de précision en élevage permettent de suivre de manière non invasive de grandes populations d’animaux sur de longues périodes. L’objectif de ce travail était de décrire l’activité ovarienne et le statut métabolique au cours de la période post-partum chez les vaches laitières, ainsi que leur impact sur la fertilité ultérieure des tro...

We deal with the problem of nonparametric estimation of a multivariate regression function without any assumption on the compacity of the support of the random design. To tackle the problem, we propose to extend a "warping" device to the multivariate framework. An adaptive warped kernel estimator is first defined in the case of known design distrib...

In metabolomics, the detection of new biomarkers from NMR spectra is a promising approach. However, this analysis remains difficult due to the lack of a whole workflow that handles spectra pre-processing, automatic identification and quantification of metabolites and statistical analyses. We present ASICS , an R package that contains a complete wor...

This article presents a Bayesian model for the clustering of non-ordered multivariate directional or circular data. The particular trait of our data is that each single observation is made up of k≥2 non-ordered points on the circle. We introduce a hierarchical model that combines a symmetrization technique, projected normal distributions and a Diri...

In an underdetermined linear system of equations, constrained l¹ minimization methods such as the basis pursuit or the lasso are often used to recover one of the sparsest representations or approximations of the system. The null space property is a sufficient and ‘almost’ necessary condition to recover a sparsest representation with the basis pursu...

Understanding the fate and ecotoxicological effects of pesticides largely depends on their molecular properties. We recently developed “TyPol” (Typology of Pollutants), a classification method of organic compounds based on statistical analyses. It combines several environmental (sorption coefficient, degradation half-life) and one ecotoxicological...

Bisphenol A (BPA) risk assessment is hampered by the difficulty of determining the extent of internal exposure in the human fetus and uncertainties regarding BPA toxicokinetics (TK) in the maternal-fetal unit. A feto-maternal TK model describing BPA and BPA glucuronide (BPAG) disposition in sheep was humanized, using human TK data obtained after d6...

IntroductionExperiments in metabolomics rely on the identification and quantification of metabolites in complex biological mixtures. This remains one of the major challenges in NMR/mass spectrometry analysis of metabolic profiles. These features are mandatory to make metabolomics asserting a general approach to test a priori formulated hypotheses o...

Metabolomics is a key approach in modern functional genomics and systems biology. Due to the complexity of metabolomics data, the variety of experimental designs, and the variety of existing bioinformatics tools, providing experimenters with a simple and efficient resource to conduct comprehensive and rigorous analysis of their data is of utmost im...

Metabolomics is a key approach in modern functional genomics and systems biology. Due to the complexity of metabolomics data, the variety of experimental designs, and the variety of existing bioinformatics tools, providing experimenters with a simple and efficient resource to conduct comprehensive and rigorous analysis of their data is of utmost im...

Chlordecone (C10Cl10O; CAS number 143–50-0) has been used extensively as an organochlorine insecticide but is nowadays banned and listed on annex A in The Stockholm Convention on Persistent Organic Pollutants (POPs). Although experimental evidences of biodegradation of this compound are scarce, several dechlorination products have been proposed by...

PLF devices allow to follow up large populations of animals in a non-invasive way over long periods of time and under field conditions. The objective of this work was to describe the ovarian activity and metabolic status during the postpartum period in dairy cows and their impact on further fertility in commercial herds. Data from 760 cows housed i...

This work focuses on the issue of variable selection in functional regression. Unlike most work in this framework, our approach does not select isolated points in the definition domain of the predictors, nor does it rely on the expansion of the predictors in a given functional basis. It provides an approach to select full intervals made of consecut...

Asymptotic normality of density estimates often requires the continuity of the underlying density and assumptions on its derivatives. Recently, these assumptions have been weakened for some estimates using the less restrictive notion of regularity index. However, the particular definition of this index makes it unusable for many estimates. In this...

The aim of this paper is to study the behavior of a covariate function in a multivariate risks scenario. The first part of this paper deals with the problem of estimating the \(c\) -upper level sets \({L(c)= \{F(x) \ge c \}}\) , with \(c \in (0,1)\) , of an unknown distribution function \(F\) on \(\mathbb {R}^d_+\) . A plug-in approach is followed....

Follow-up is more and more used in medicine/doping control to identify abnormal results in an individual. Currently, follow-ups are mostly carried out variable by variable using "reference intervals" that contain the values observable in 100(1-α)% of healthy/undoped individuals. Observations of the evolution of the variables over time in a sample o...

Let (X,Y)(X,Y) be a random pair taking values in Rd×JRd×J, where J⊂RJ⊂R is supposed to be bounded. We propose a plug-in estimator of the level sets of the regression function rr of YY on XX, using a kernel estimator of rr. We consider an error criterion defined by the volume of the symmetrical difference between the real and estimated level sets. W...

Using quantization techniques, Laloë (2010) defined a new algorithm called Alter. This L 1 -based algorithm is proved to be convergent, but suffers two shortcomings. First, the number of clusters K has to be supplied by the user. Second, it has high complexity. In this article, we adapt the idea of X-means algorithm by Pelleg and Moore (2000) to of...

In this paper, we study an unsupervised clustering problem. The originality of this problem lies in the data, which consist of the positions of five separate X-ray beams on a circle. Radiation therapists positioned the five X-ray beam 'projectors' around each patient on a predefined circle. However, similarities exist in positioning for certain gro...

The index of regularity of a measure was introduced by Beirlant, Berlinet and Biau [1] to solve practical problems in nearest neighbour density estimation such as removing bias or selecting the number of neighbours. These authors proved the weak consistency of an estimator based on the nearest neighbour density estimator. In this paper, we study an...

Many convergence results in density estimation can be stated without any restriction on the function to be estimated. Unlike these universal properties, the asymptotic normality of estimators often requires hypotheses on the derivatives of the underlying density and additional conditions on the smoothing parameter. Yet, despite the possible bad loc...

L'estimateur des plus proches voisins de la densité est un estimateur simple et facile à mettre en oeuvre. Sa normalité asymptotique a été établie par Moore et Yackel~(1977) sous des hypothèses faisant intervenir les dérivées de la densité. Sans faire d'hypothèse de continuité sur la densité, nous donnons une condition nécessaire et suffisante de c...

La dérivée symétrique d'une mesure de probabilité en un point de Lebesgue peut souvent être approximée à l'aide d'un développement faisant intervenir un indice de régularité. La connaissance de cet indice est d'un intérêt pratique. En effet, il permet par exemple de déterminer le comportement local de la mesure étudiée. Il intervient aussi dans l'é...