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The CT1 mutant of Penicillium occitanis hyperproduces extracellular pectinases constitutively since it secretes pectinases even on glucose-containing medium. We show here that all other hydrolytic enzymes remain at low activities in CT1, confirming the specificity of the regulatory mutation towards pectinases. We isolated, by RT-PCR and through the construction of a cDNA library, three fragments coding for: a pectin lyase (pnl1), a polygalacturonase (pga1) and a pectate lyase (pal1). These fragments were used as probes in Northern blots analysis of the wild type strain CL100 and the CT1 mutant of P. occitanis grown in three culture conditions. The CT1 mutant showed a very high amount of pnl1, pga1 and pal1 mRNA either in pectin, glucose or glycerol grown cells while in the wild type CL100 strain, all transcripts were undetectable even on pectin. These results suggest that the CT1 mutation affects a trans-regulatory transcriptional factor regulating pectinase expression.

We show in this paper that the emerging topological gradient method is a new way for modelling and solving image restoration problems. This method is considered in the frame of variational diffusive approaches for the minimization of potential energy with respect to conductivity. The numerical experiments show the efficiency of the topological gradient approach. The image is restored at the first iteration of the optimization process. Moreover, the computational cost of this iteration is reduced drastically using spectral methods.

We are interested in finding out the best way to smooth noisy data using cubic B-splines. Two small parameters are involved: the noise level ϵ, and the splines path h. The error in maximum norm between the actual data and the smoothed noisy ones is proved to be an O ( ϵ + h 2 ) , which leads to the choice of a splining path h = O ( ϵ ) . Error estimates on the derivatives are also provided, and a splining protocol is derived from them, which ensures an O ( ϵ 1 2 p ) maximum norm error on the p-th derivatives. To cite this article: S. Chaabane et al., C. R. Acad. Sci. Paris, Ser. I 346 (2008).

Aeluropus littoralis (Gouan) Parl. is a C4 perennial halophyte monocotyledonous plant belonging to the same family of wheat. Growing as weed in dry salty areas or marshes, it is a salt-secreting, rhizomatous and is used as forage. It is diploid (2n=2X=14) and has a relative small genome of around 342 Mb. A. littoralis is highly salt-tolerant since this plant has the ability to secrete salt. Thus, A. littoralis has the potential to become an important genetic resource for biotechnological strategies to improve salt and drought tolerance in economically important crops such as wheat. We have constructed SSH (Suppression Subtractive Hybridization) cDNA libraries from root (RSD45) and leaf (LSD45) tissues of 45 days old plants grown in the presence of 300 mM NaC1. We have also constructed full-length cDNA library from 15 days old salt stressed (300 mM NaC1) roots (RSTL15). Sequencing revealed 25 and 42 independent transcripts from the RSD45 and LSD45 cDNA libraries respectively, in both cases this was less than 25% of the clones sequenced. In contrast, 425 (60%) of the clones from the RSTL15 library revealed independent transcripts. After comparison with protein databases using BlastX, 335 (68%) ESTs (Expressed Sequence Tag) were classified into putative known functions and unclassified proteins, 59 (12%) have homology only to unidentified homologous sequences. A total of 98 (20%) of the ESTs have no homologies to known sequences in the protein databases which can be considered as novel. © 2007 Elsevier B.V. All rights reserved.

A new method for edge detection and image restoration is proposed. This method is based on topological gradient approach. Experimental results obtained on noisy images illustrate the capabilities of this promising method in image processing. To cite this article: L.J. Belaid et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006).

We establish some global stability results together with logarithmic estimates in Sobolev norms for the inverse problem of recovering a Robin coefficient on part of the boundary of a smooth 2D domain from overdetermined measurements on the complementary part of a solution to the Laplace equation in the domain, using tools from analytic function theory.

We consider the inverse problem of determining a crack submitted to a non linear impedance law. Identifiability and local Lipschitz stability results are proved for both the crack and the impedance.

We consider the inverse problem of identifying a Robin coefficient on some part of the boundary of a smooth 2D domain from overdetermined data available on the other part of the boundary, for Laplace equation in the domain. Using tools from complex analysis and analytic functions theory, we provide a constructive and convergent identification scheme for this inverse problem, together with numerical experiments.

We are interested in this paper in recovering an harmonic function from the knowledge of Cauchy data on some part of the boundary. The inverse scheme reduces the Cauchy problem resolution to a fixed point process. It is proved, when the data are compatible, this fixed point process converges to the Cauchy problem solution. The algorithm is implemented in both situations, firstly in the framework of boundary elements and secondly in a finite element one. Displayed numerical results highlight their accuracy, as well as their robustness to noisy data. Finally we present the contribution of the method to solve an engineering problem which consists in determining temperature and heat flux on the inner cylinder wall from the knowledge of temperatures and heat flux on the whole outer wall.

We are interested in this article in recovering line segment (or planar) cracks from incomplete boundary measurements. Most recovery algorithms, and especially fast ones based on the reciprocity gap, however need a full set of boundary data, which compels us to extending the available data prior to achieving recovery. Both the extension and recovery problems being severely ill posed, their stacking might drive the whole process to a blowing up, unless the instabilities are properly handled. Numerical results actually prove the so-built composite algorithm to hold good accuracy and robustness features.

We are interested in this paper in recovering lacking data on some part of a domain boundary, from the knowledge of Cauchy data on the other part. It is first proved that the desired solution is the unique fixed point of some appropriate operator, which naturally gives rise to an iterative process that is proved to be convergent. Discretization provides an additional regularization: the algorithm reads as a least square fitting of the given data, with a regularization term the effect of which fades as iterations go on. Displayed numerical results highlight its accuracy, as well as its robustness.

On s'interesse dans ce travail a un probleme inverse non lineaire d'identification d'une frontiere inconnue $\gamma$ par des mesures de surfaces, les conditions aux limites imposees sur cette frontiere $\gamma$ etant de type Signorini. Le probleme est d'abord transforme en un probleme d'optimisation de forme, par la definition d'une fonction de type Kohn-Vogelius, dont nous montrons que le seul minimum est la frontiere recherchee, et que le gradient dans une direction donnee $\theta$ ne depend que du seul etat $u^0$, et non de sa derivee Lagrangienne $u^1(\theta)$.

Research was undertaken to investigate whether low, medium or high molecular-mass polyphenolics were the most problematic compounds for olive mill wastewater (OMW) biotreatments. For this reason, three polyphenolic fractions were isolated by ultrafiltration of crude OMW and characterized by GC/MS and gel filtration analysis. When P. chrysosporium was cultivated in the presence of F1 polyphenolic fraction (F1 60 kDa) was observed. Lignin peroxidase (LiP) was detected as traces for the F1 fraction and undetected in the case of F3 one. Moreover, increasing the molecular-mass of aromatics led to decreases in levels of depolymerization and COD removal by P. chrysosporium cultures. The use of a lignin peroxidase induction medium has a positive effect on the high molecular-mass fraction decolorization and a high degree of decolorization paralleled the appearance of LiP activity in the extracellular fluid. By comparison to the synthetic medium used, LiP production was delayed in the presence of F1 fraction but strongly inhibited (80% loss) in the presence of F3 fraction. The F1 fraction was well degraded aerobically by P. putida DSM3932 (pWWO) and A. eutrophus DSM 4057 (pJP3) or an activated sludge consortium while F3 resisted degradation by the OMW-acclimated activated sludge. Moreover, continuous anaerobic biomethanization experiments conducted in parallel with the different fractions showed that at the same hydraulic retention time (26 days), the F1 fraction was bioconverted into methane at high yield while F3 fraction was poorly biodegraded.

We consider the problem of determining the Robin coefficient of some specimen material, by performing measurements on some part of the boundary. An identifiability result is proved for Robin coefficients which are continuous functions with some negative lower bound. Both local and monotone global Lipschitz stability results are established. Finally, a cost function turning the inverse problem into an optimization one is proposed for numerical purposes. This function, which may be viewed as an energetic least-squares one, has an easy-to-compute G-derivative, which encourages us to consider implementing the gradient algorithm in forthcoming numerical experiments.

The purpose of this work is to identify two-dimensional (2D) cracks by means of elastic boundary measurements. A uniqueness result is first proved in the general case, as well as the local Lipschitzian stability in the case of line segment emergent cracks. In this last case, the search for the unique zero of the reciprocity gap functional related to the singular solution of the elasticity problem provides a fast algorithm to determine the unknown crack tip.

This report deals with a non linear inverse problem of identification of unknown boundaries, on which the prescribed conditions are of Signorini type. We first prove an identifiability result, in both frameworks of steady state thermal and elastostatics testing. Local Lipschitz stability of the solutions with respect to the boundary measurements is also established, in case of unknown boundaries which are parts of ${\cal C}^{1,\beta}$ Jordan curves, with $\beta > 0$.

This paper deals with the detection of emerging plane cracks, by using boundary measurements. An identifiability result (uniqueness of the solution) is first proved. Then, we look at the stability of this solution with respect to the measurement. A weak stability result is proved, as well as a local Lipshitz stability result for straight cracks, by using domain-derivative techniques.

This paper deals with a semi-explicit algorithm to reconstruct two-dimensional (2D) segment cracks, or three-dimensional (3D) planar cracks, in the framework of overspecified boundary data. The algorithm is based on the reciprocity gap concept, introduced by Andrieux and Ben Abda, which provides explicitly the line (or the plane) support of the cracks. A numerical reconstruction of the cracks, which are actually the support of the solution jump across this plane, is then performed by computing the Fourier expansion of the solution jump itself. After the numerical analysis of the method, some numerical results are presented and commented on.

The Arab Spring of 2011 has highlighted an unprecedent fact in the region: it was the young and educated population who established the spearheading of change, and led their countries to democracy. In this paper, we try to analyze how science has been a key factor in these moves, in Tunisia as well as in Egypt, and how it can help to anchor democracy in these countries.

The moulds filling process may generate flaws consisting in small gas bubbles trapped inside the material, which weaken the solidity of the casted piece. We consider here the inverse problem of determining these small size flaws locations from velocities boundary measurements. The fluid flow is described by a simplified model based on the Stokes system. A numerical algorithm based on the topological sensitivity analysis applied to an energy like misfit functional, is worked out to that end.

Foreword to the special issue of Arima Journal dedicated to TAM-TAM'09

See also INRIA RR-6456 (2008); International audience; We consider the Cauchy problem of recovering both Neumann and Dirichlet data on the inner part of the boundary of an annular domain from measurements of a harmonic function on some part of the outer boundary. Using tools from complex analysis and best approximation in Hardy classes, we present a family of fast data completion algorithms which are shown to provide constructive and robust identification schemes. These are applied to the computation of an impedance or Robin coefficient and are validated by a thorough numerical study.

The moulds' filling process may generate flaws consisting of small gas bubbles trapped inside the material, which weaken the solidity of the casted piece. We consider here the inverse problem of determining these small size flaws' locations from velocities boundary measurements. The fluid flow is described by a simplified model based on the Stokes system. A numerical algorithm based on the topological sensitivity analysis applied to an energy-like misfit functional is worked out to that end.

The problem we are dealing with is to recover a Robin coefficient (or impedance) from measurements performed on some part of the boundary of a domain, in the framework of nondestructive testing by the means of Electric Impedance Tomography. The impedance can provide information on the location of a corroded area, as well as on the extent of the damage, which has possibly occurred on an unaccessible part of the boundary. Two different identification algorithms are presented and studied: the first one is based on a Kohn and Vogelius cost function, actually an energetic least squares one, which turns the inverse problem into an optimization one ; as for the second, it makes use of the best approximation in Hardy classes, in order to extend the Cauchy data to the unreachable part of the boundary, and then compute the Robin coefficient from these extended data. Special focus is put on the robustness with respect to noise, both from a mathematical and and numerical point of view. Some numerical experiments are eventually presented and compared., Dans ce travail nous nous sommes intéressé à un problème d’identification d’un coefficient de Robin (ou une impédence) à partir de mesures effectuées sur une certaine partie de la frontière d’un domaine. Ce problème est motivé par le contrôle non destructif des matériaux en tomographie par impédance électrique. L’impédance peut fournir des informations sur l’emplacement d’une zone de corrosion, ainsi que sur l’étendue des dommages, qui a peut-être eu lieu sur une partie inaccessible de la frontière. Deux algorithmes d’identification sont présentés et étudiés: le premier est basé sur la minimisation des fonctionnelles d’écart énergétiques, dite de Kohn et Vogelius, comme pour le second, il fait usage à l’approximation dans les classes de Hardy afin de prolonger les données de Cauchy à la partie inaccessible de la frontière, puis calculer le coefficient de Robin qui est le quotient de ces données étendues. L’accent est mis sur la robustesse par rapport au bruit, à la fois d’un point de vu mathématique et numérique. Des expériences numériques sont finalement présentées et comparées.

We consider the inverse problem of identifying a Robin coefficient on some part of the boundary of a smooth 2D domain from overdetermined data available on the other part of the boundary, for Laplace equation in the domain. Using tools from complex analysis and analytic functions theory, we provide a constructive and convergent identification scheme, together with a stability result for this inverse problem.