Rearing method of Oryzaephilus surinamensis (L.) (Coleoptera, Silvanidae) on various wheat grain granulometry

Oryzaephilus surinamensis is one of most common insect pest of grains and a variety of stored products, and has been found in high numbers in almost all storage facilities. However, laboratory mass rearing of this insect for bioassays is not a simple task, mainly because of its feeding behavior, small size, and high mobility. Thus, the aim of this work was to develop a simple and efficient laboratory rearing method for O. surinamensis, using wheat kernels milled into different granulometry to obtain large number and standardized population at different life stages for bioassays. The adults were collected from storage grain facilities in the southern region of Brazil and 100 specimens were placed inside glass jars with wheat kernels milled at different grades and kept at 25±0.5ºC and 65±5% relative humidity. The insects were allowed to copulate and lay eggs for 10 days and then removed. The number of eggs, larvae, and pupae was counted at five-day intervals; longevity of the second generation adults was evaluated. The kernels milled at grade 20 were the best medium for offspring production: 89% of eggs by the 5th day; 30.5% larvae by the 10th day; 43% pupae by the 30th day and 63.4% adults at the 46th day. The adults survived up to 450 days. Culturing O. surinamensis under the described conditions, transferring the parental adults by the 10th day after infestation and replacing the media when population builds up will produce enough insects of each stage for various laboratory bioassays.

A new alternative method for testing skin irritation using a human skin model: a pilot study.

Studies assessing skin irritation to chemicals have traditionally used laboratory animals; however, such methods are questionable regarding their relevance for humans. New in vitro methods have been validated, such as the reconstructed human epidermis (RHE) model (Episkin®, Epiderm®). The comparison (accuracy) with in vivo results such as the 4-h human patch test (HPT) is 76% at best (Epiderm®). There is a need to develop an in vitro method that better simulates the anatomo-pathological changes encountered in vivo. To develop an in vitro method to determine skin irritation using human viable skin through histopathology, and compare the results of 4 tested substances to the main in vitro methods and in vivo animal method (Draize test). Human skin removed during surgery was dermatomed and mounted on an in vitro flow-through diffusion cell system. Ten chemicals with known non-irritant (heptylbutyrate, hexylsalicylate, butylmethacrylate, isoproturon, bentazon, DEHP and methylisothiazolinone (MI)) and irritant properties (folpet, 1-bromohexane and methylchloroisothiazolinone (MCI/MI)), a negative control (sodiumchloride) and a positive control (sodiumlaurylsulphate) were applied. The skin was exposed at least for 4h. Histopathology was performed to investigate irritation signs (spongiosis, necrosis, vacuolization). We obtained 100% accuracy with the HPT model; 75% with the RHE models and 50% with the Draize test for 4 tested substances. The coefficients of variation (CV) between our three test batches were <0.1, showing good reproducibility. Furthermore, we reported objectively histopathological irritation signs (irritation scale): strong (folpet), significant (1-bromohexane), slight (MCI/MI at 750/250ppm) and none (isoproturon, bentazon, DEHP and MI). This new in vitro test method presented effective results for the tested chemicals. It should be further validated using a greater number of substances; and tested in different laboratories in order to suitably evaluate reproducibility.

Optimization of multiclass queueing networks with changeover times via the achievable region method: Part II, the multi-station case

We address the problem of scheduling a multi-station multiclassqueueing network (MQNET) with server changeover times to minimizesteady-state mean job holding costs. We present new lower boundson the best achievable cost that emerge as the values ofmathematical programming problems (linear, semidefinite, andconvex) over relaxed formulations of the system's achievableperformance region. The constraints on achievable performancedefining these formulations are obtained by formulatingsystem's equilibrium relations. Our contributions include: (1) aflow conservation interpretation and closed formulae for theconstraints previously derived by the potential function method;(2) new work decomposition laws for MQNETs; (3) new constraints(linear, convex, and semidefinite) on the performance region offirst and second moments of queue lengths for MQNETs; (4) a fastbound for a MQNET with N customer classes computed in N steps; (5)two heuristic scheduling policies: a priority-index policy, anda policy extracted from the solution of a linear programmingrelaxation.

A data-dependent skeleton estimate and a scale-sensitive dimension for classification

The classical binary classification problem is investigatedwhen it is known in advance that the posterior probability function(or regression function) belongs to some class of functions. We introduceand analyze a method which effectively exploits this knowledge. The methodis based on minimizing the empirical risk over a carefully selected``skeleton'' of the class of regression functions. The skeleton is acovering of the class based on a data--dependent metric, especiallyfitted for classification. A new scale--sensitive dimension isintroduced which is more useful for the studied classification problemthan other, previously defined, dimension measures. This fact isdemonstrated by performance bounds for the skeleton estimate in termsof the new dimension.

A time-domain method for the analysis of thermal impedance response preserving the convolution form

The study of the thermal behavior of complex packages as multichip modules (MCM¿s) is usually carried out by measuring the so-called thermal impedance response, that is: the transient temperature after a power step. From the analysis of this signal, the thermal frequency response can be estimated, and consequently, compact thermal models may be extracted. We present a method to obtain an estimate of the time constant distribution underlying the observed transient. The method is based on an iterative deconvolution that produces an approximation to the time constant spectrum while preserving a convenient convolution form. This method is applied to the obtained thermal response of a microstructure as analyzed by finite element method as well as to the measured thermal response of a transistor array integrated circuit (IC) in a SMD package.

Genetic association tests: a method for the joint analysis of family and case-control data.

With the trend in molecular epidemiology towards both genome-wide association studies and complex modelling, the need for large sample sizes to detect small effects and to allow for the estimation of many parameters within a model continues to increase. Unfortunately, most methods of association analysis have been restricted to either a family-based or a case-control design, resulting in the lack of synthesis of data from multiple studies. Transmission disequilibrium-type methods for detecting linkage disequilibrium from family data were developed as an effective way of preventing the detection of association due to population stratification. Because these methods condition on parental genotype, however, they have precluded the joint analysis of family and case-control data, although methods for case-control data may not protect against population stratification and do not allow for familial correlations. We present here an extension of a family-based association analysis method for continuous traits that will simultaneously test for, and if necessary control for, population stratification. We further extend this method to analyse binary traits (and therefore family and case-control data together) and accurately to estimate genetic effects in the population, even when using an ascertained family sample. Finally, we present the power of this binary extension for both family-only and joint family and case-control data, and demonstrate the accuracy of the association parameter and variance components in an ascertained family sample.

Evaluation of Sikora instead of SMP buffer to estimate the potential acidity of brazilian soils

Despite the efficiency of the Shoemaker, McLean, Pratt (SMP) buffer method in estimating soil acidity, the presence of p-nitrophenol and potassium chromate in the solution, both hazardous substances, has caused increasing environmental concerns. The purpose of this study was to test Sikora method (Sikora, 2006) as an alternative to the adapted SMP buffer method, generally used to estimate potential acidity of Southern Brazilian soils. For the test, 21 soils in the South and Cerrado regions of Brazil were sampled. (1) The potential acidity values of these soils range from 35.95 to 4.02 cmol c kg-1 of soil, reflecting a wide acidity variation. The Sikora buffer does not mimic the adapted SMP buffer used in Southern Brazil, since the former has a low ability to distinguish soils with different acidity from each other, probably due to the higher buffer capacity than of the adapted SMP solution.

Incline, speed, and distance assessment during unconstrained walking.

Body accelerations during human walking were recorded by a portable measuring device. A new method for parameterizing body accelerations and finding the pattern of walking is outlined. Two neural networks were designed to recognize each pattern and estimate the speed and incline of walking. Six subjects performed treadmill walking followed by self-paced walking on an outdoor test circuit involving roads of various inclines. The neural networks were first "trained" by known patterns of treadmill walking. Then the inclines, the speeds, and the distance covered during overground walking (outdoor circuit) were estimated. The results show a good agreement between actual and predicted variables. The standard deviation of estimated incline was less than 2.6% and the maximum of the coefficient of variation of speed estimation is 6%. To the best of our knowledge, these results constitute the first assessment of speed, incline and distance covered during level and slope walking and offer investigators a new tool for assessing levels of outdoor physical activity.

A new accelerometric method to assess the daily walking practice.

OBJECTIVE: To describe a method to obtain a profile of the duration and intensity (speed) of walking periods over 24 hours in women under free-living conditions. DESIGN: A new method based on accelerometry was designed for analyzing walking activity. In order to take into account inter-individual variability of acceleration, an individual calibration process was used. Different experiments were performed to highlight the variability of acceleration vs walking speed relationship, to analyze the speed prediction accuracy of the method, and to test the assessment of walking distance and duration over 24-h. SUBJECTS: Twenty-eight women were studied (mean+/-s.d.) age: 39.3+/-8.9 y; body mass: 79.7+/-11.1 kg; body height: 162.9+/-5.4 cm; and body mass index (BMI) 30.0+/-3.8 kg/m(2). RESULTS: Accelerometer output was significantly correlated with speed during treadmill walking (r=0.95, P<0.01), and short unconstrained walks (r=0.86, P<0.01), although with a large inter-individual variation of the regression parameters. By using individual calibration, it was possible to predict walking speed on a standard urban circuit (predicted vs measured r=0.93, P<0.01, s.e.e.=0.51 km/h). In the free-living experiment, women spent on average 79.9+/-36.0 (range: 31.7-168.2) min/day in displacement activities, from which discontinuous short walking activities represented about 2/3 and continuous ones 1/3. Total walking distance averaged 2.1+/-1.2 (range: 0.4-4.7) km/day. It was performed at an average speed of 5.0+/-0.5 (range: 4.1-6.0) km/h. CONCLUSION: An accelerometer measuring the anteroposterior acceleration of the body can estimate walking speed together with the pattern, intensity and duration of daily walking activity.

Replication of an ivg protocol to estimate bioaccessible arsenic in materials from a gold mining area in Brazil

Tests for bioaccessibility are useful in human health risk assessment. No research data with the objective of determining bioaccessible arsenic (As) in areas affected by gold mining and smelting activities have been published so far in Brazil. Samples were collected from four areas: a private natural land reserve of Cerrado; mine tailings; overburden; and refuse from gold smelting of a mining company in Paracatu, Minas Gerais. The total, bioaccessible and Mehlich-1-extractable As levels were determined. Based on the reproducibility and the accuracy/precision of the in vitro gastrointestinal (IVG) determination method of bioaccessible As in the reference material NIST 2710, it was concluded that this procedure is adequate to determine bioaccessible As in soil and tailing samples from gold mining areas in Brazil. All samples from the studied mining area contained low percentages of bioaccessible As.

Potential acidity estimated by SMP pH in soils of the state of Pará

The use of SMP pH to estimate the potential acidity (H + Al) is more practical than the method of 0.5 mol L-1 calcium acetate for routine laboratory analyses. The objective was to fit an equation to estimate the H + Al from SMP pH values of soils of the State of Pará. From various regions of the state, 177 soil samples were collected, in which the SMP pH was determined in 0.01 mol L-1 CaCl2 solution and H + Al in 0.5 mol L-1 calcium acetate and the results were related by regression analysis. The equation H + Al = 77.77 + 20.61 SMP pH - 1.435 SMP pH² (R² = 0.90) expressed the H + Al values (in cmol c dm-3) best. When the SMP pH values were used in equations referring to other regions or states in Brazil, the H +Al values were over- or underestimated. The potential acidity in soils of Pará can be estimated by the method of SMP pH.

Pedotransfer functions to estimate water retention parameters of soils in northeastern Brazil

Pedotransfer functions (PTF) were developed to estimate the parameters (α, n, θr and θs) of the van Genuchten model (1980) to describe soil water retention curves. The data came from various sources, mainly from studies conducted by universities in Northeast Brazil, by the Brazilian Agricultural Research Corporation (Embrapa) and by a corporation for the development of the São Francisco and Parnaíba river basins (Codevasf), totaling 786 retention curves, which were divided into two data sets: 85 % for the development of PTFs, and 15 % for testing and validation, considered independent data. Aside from the development of general PTFs for all soils together, specific PTFs were developed for the soil classes Ultisols, Oxisols, Entisols, and Alfisols by multiple regression techniques, using a stepwise procedure (forward and backward) to select the best predictors. Two types of PTFs were developed: the first included all predictors (soil density, proportions of sand, silt, clay, and organic matter), and the second only the proportions of sand, silt and clay. The evaluation of adequacy of the PTFs was based on the correlation coefficient (R) and Willmott index (d). To evaluate the PTF for the moisture content at specific pressure heads, we used the root mean square error (RMSE). The PTF-predicted retention curve is relatively poor, except for the residual water content. The inclusion of organic matter as a PTF predictor improved the prediction of parameter a of van Genuchten. The performance of soil-class-specific PTFs was not better than of the general PTF. Except for the water content of saturated soil estimated by particle size distribution, the tested models for water content prediction at specific pressure heads proved satisfactory. Predictions of water content at pressure heads more negative than -0.6 m, using a PTF considering particle size distribution, are only slightly lower than those obtained by PTFs including bulk density and organic matter content.

Pedotransfer functions to estimate retention and availability of water in soils of the state of Santa Catarina, Brazil

Studies on water retention and availability are scarce for subtropical or humid temperate climate regions of the southern hemisphere. The aims of this study were to evaluate the relations of the soil physical, chemical, and mineralogical properties with water retention and availability for the generation and validation of continuous point pedotransfer functions (PTFs) for soils of the State of Santa Catarina (SC) in the South of Brazil. Horizons of 44 profiles were sampled in areas under different cover crops and regions of SC, to determine: field capacity (FC, 10 kPa), permanent wilting point (PWP, 1,500 kPa), available water content (AW, by difference), saturated hydraulic conductivity, bulk density, aggregate stability, particle size distribution (seven classes), organic matter content, and particle density. Chemical and mineralogical properties were obtained from the literature. Spearman's rank correlation analysis and path analysis were used in the statistical analyses. The point PTFs for estimation of FC, PWP and AW were generated for the soil surface and subsurface through multiple regression analysis, followed by robust regression analysis, using two sets of predictive variables. Soils with finer texture and/or greater organic matter content retain more moisture, and organic matter is the property that mainly controls the water availability to plants in soil surface horizons. Path analysis was useful in understanding the relationships between soil properties for FC, PWP and AW. The predictive power of the generated PTFs to estimate FC and PWP was good for all horizons, while AW was best estimated by more complex models with better prediction for the surface horizons of soils in Santa Catarina.

Ecotoxicological approaches to assess the long-term effects of four anticancer drugs and metabolites on Daphnia pulex

The aquatic environment is exposed continuously and increasingly to chemical substances such as pharmaceuticals. These medical compounds are released into the environment after having being consumed and body-excreted by patients. Pharmaceutical residues are synthetic molecules that are not always removed by traditional sewage treatment processes and thus escape degradation. Among pharmaceuticals that escape sewage treatment plants (STPs), the anticancer drugs were measured in STP effluents and natural waters. In the aquatic environment, their long-term effects at low concentrations are sparsely known on non-target species. Tamoxifen is an anticancer drug that is widely prescribed worldwide for the prevention and treatment of hormone receptor-positive breast cancers. Two of its metabolites, i.e., endoxifen and 4-hydroxy- tamoxifen (4OHTam), have high pharmacological potency in vivo and such as tamoxifen, they are excreted via faeces by patients. Tamoxifen was measured in STP effluents and natural waters but, to the best of our knowledge, its metabolites concentrations in waters have never been reported. Imatinib is another and recent anticancer compound that targets specific tumour cells. This pharmaceutical is also body excreted and because of its increasing use in cancer treatment, imatinib may reach the natural water. The effects of tamoxifen and imatinib are unknown upon more than one generation of aquatic species. And the effects of 4OHTam, endoxifen have never been studied in ecotoxicology so far. The aims of this thesis were threefold. First, the sensitivity of D. pulex exposed to tamoxifen, 4OHTam, endoxifen or imatinib was assessed using ecotoxicological experiments. Ecotoxicology is the science that considers the toxic effects of natural or synthetic substances, such as pharmaceuticals, on organisms, populations, community and ecosystem. Acute and multigenerational (2-4 generations) tests were performed on daphnids considering several studied endpoints, such as immobilisation, size, reproduction, viability and intrinsic rate of natural increase. Additional prospective assays were designed to evaluate whether 1) low concentrations of tamoxifen and 4OHTam were able to induce toxic effects when used in combination, and 2) daphnids were able to recover when offspring were withdrawn from solutions carrying the pharmaceutical. Second, the stability of tamoxifen, 4OHTam and endoxifen in incubation medium was evaluated in solution exempted from daphnids. Because the nominal concentrations of tamoxifen, 4OHTam and endoxifen did not correspond to the measured, we provide a predictive method to estimate the concentrations of these chemicals during long-term ecotoxicological tests. Finally, changes in protein expressions were analysed in D. pulex exposed 2 or 7 seven days to tamoxifen using ecotoxicoproteomic experiments with a shot-gun approach inducing a peptide fractionation step. Our results show that tamoxifen, 4OHTam and endoxifen induced adverse effects in D. pulex at environmentally relevant concentrations. At very low concentrations, these molecules displayed unusual and teratogenic effects because morphological abnormalities were observed in offspring, such as thick and short antennas, curved spines, premature neonates and aborted eggs. Tamoxifen was the most toxic compound among the test chemicals, followed by 4OHTam, endoxifen and imatinib. Tamoxifen no-observed effect concentrations (NOECs) that were calculated for size, reproduction and intrinsic rate were below or in the range of the concentrations measured in natural waters, i.e., between 0.12 µg/L and 0.67 µg/L. For instance, the tamoxifen NOECs that were calculated for reproduction were between 0.67 and 0.72 µg/L, whereas the NOEC was < 0.15 µg/L when based on morphological abnormalities. The NOECs of 4OHTam were higher but still in the same order of magnitude as tamoxifen environmental concentrations, with a value of 1.48 µg/L. Endoxifen NOEC for the intrinsic rate of natural increase (r) and the reproduction were 0.4 and 4.3 µg/L, respectively. Daphnids that were withdrawn from tamoxifen and 4OHTam were not able to recover. Also, the reproduction of D. pulex was reduced when the treated animals were exposed to the combination of tamoxifen and 4OHTam while no effects were observed when these chemicals were tested individually at the same concentration. Among the anticancer drugs that were tested during this thesis, imatinib was the less toxic molecule towards D. pulex. No effects on size and reproduction were observed within two generations, except for the first whose reproduction decreased at the highest test concentration, i.e., 626 µg/L. Our results also underline the need to use measured or predicted concentrations instead of the nominal during aquatic experiments, particularly when lipophilic molecules are tested. Indeed, notable differences between nominal (i.e., theoretical) and measured concentrations were found with tamoxifen, 4OHTam and endoxifen at all test concentrations. A cost and time sustainable method was proposed to predict the test exposure levels of these chemicals during long-term experiments. This predictive method was efficient particularly for low concentrations, which corresponded to the test concentrations in multigenerational tests. In the ecotoxicoproteomic experiments a total of 3940 proteins were identified and quantified in D. pulex exposed to tamoxifen. These results are currently the largest dataset from D. pulex that is published and the results of proteomic analyses are available for the scientific community. Among these 3940 proteins, 189 were significantly different from controls. After protein annotation, we assumed that treated daphnids with tamoxifen had shifted cost-energy functions, such as reproduction, to maintain their basic metabolism necessary to survive. This metabolic cost hypothesis was supported by the presence of proteins involved in oxidative stress. Biomarkers for early detection of tamoxifen harmful effects on D. pulex were not discovered but the proteins of the vitellogenin-2 family (E9H8K5) and the ryanodine receptor (E9FTU9) are promising potential biomarkers because their expression was already modified after 2 days of treatment. In this thesis, the effects of tamoxifen, 4OHTam and endoxifen on daphnids raise questions about the potential impact of tamoxifen and 4OHTam in other aquatic ecosystems, and therefore, about metabolites in ecotoxicology. Because the NOECs were environmentally relevant, these results suggest that tamoxifen and 4OHTam may be interesting pharmaceuticals to consider in risk assessment. Our findings also emphasize the importance of performing long-term experiments and of considering multi-endpoints instead of the standard reproductive endpoint. Finally, we open the discussion about the importance to measure test exposures or not, during ecotoxicological studies. -- Les milieux aquatiques sont exposés continuellement à un nombre croissant de substances chimiques, notamment les médicaments issus de la médecine vétérinaire et humaine. Chez les patients, les substances administrées sont utilisées par le corps avant d'être éliminées par l'intermédiaire des excrétas dans le système d'eaux usées de la ville. Ces eaux rejoignent ensuite une station de traitement afin d'y éliminer les déchets. Dans le cas des molécules chimiques, il arrive que les processus de traitement d'eaux usées ne soient pas suffisamment efficaces et que ces molécules ne soient pas dégradées. Elles sont alors libérées dans le milieu aquatique avec les effluents de la station d'épuration. Une fois dans l'environnement, ces résidus de médicaments sont susceptibles d'induire des effets sur la faune et la flore aquatique, dont les conséquences à long terme et à faibles concentrations sont peu connues. Les anticancéreux sont une famille de médicaments qui peuvent échapper aux traitements des stations d'épuration et qui sont retrouvées dans le milieu aquatique naturel. Parmi ces substances, le tamoxifen est une molécule utilisée dans le monde entier pour prévenir et traiter les cancers hormonaux dépendant du sein, notamment. Une fois ingéré, le tamoxifen est transformé par le foie en métabolites dont deux d'entre eux, le 4-hydroxy-tamoxifen (4OHTam) et l'endoxifen, possèdent un affinité pour les récepteurs aux estrogènes et une efficacité sur les cellules tumorales supérieure au tamoxifen lui- même. Tout comme la molécule mère, ces métabolites sont principalement éliminés par l'intermédiaire des fèces. Le tamoxifen a déjà été mesuré dans les effluents de stations d'épuration et dans les eaux naturelles, mais aucune valeur n'a été reportée pour ses métabolites jusqu'à présent. Un autre anticancéreux, également éliminé par voie biliaire et susceptible d'atteindre l'environnement, est l'imatinib. Cette récente molécule a révolutionné le traitement et la survie des patients souffrant de leucémie myéloïde chronique et de tumeur stromales gastrointestinales. Les effets du tamoxifen et de l'imatinib sur plusieurs générations d'organismes aquatiques, tels que les microcrustacés Daphnia, sont inconnus et le 4OHTam et l'endoxifen n'ont même jamais été testés en écotoxicologie. Cette thèse s'est articulée autour de trois objectifs principaux. Premièrement, la sensibilité des D. pulex exposés au tamoxifen, 4OHTam, endoxifen et imatinib a été évaluée par l'intermédiaire de tests aigus et de tests sur deux à quatre générations. La mobilité, la taille, la reproduction, la viabilité et la croissance potentielle de la population ont été relevées au cours de ces expériences. Des tests supplémentaires, à but prospectifs, ont également été réalisés afin d'évaluer 1) la capacité de récupération des daphnies, lorsque leurs descendants ont été placés dans un milieu exempté de tamoxifen ou de 4OHTam, 2) les effets chez les daphnies exposées à une solution contenant de faibles concentration de tamoxifen et de 4OHTam mélangés. Le deuxième objectif a été d'évaluer la stabilité du tamoxifen, 4OHTam et endoxifen dilué dans le milieu des daphnies. Après analyses, les concentrations mesurées ne correspondaient pas aux concentrations nominales (c.-à-d., théoriques) et il a été nécessaire de développer une méthode efficace de prédiction des niveaux d'exposition lors de tests de longue durée réalisés avec ces trois molécules. Finalement, des changements dans l'expression des protéines chez des daphnies exposées au tamoxifen ont été investigués par l'intermédiaire d'expériences écotoxicoprotéomiques avec une approche dite de shot-gun avec une étape de fractionnement des protéines. Les résultats obtenus dans cette thèse montrent que le tamoxifen, le 4OHTam et l'endoxifen induisent des effets indésirables chez les daphnies à des niveaux d'exposition proches ou identiques aux concentrations du tamoxifen mesurées dans l'environnement, c'est-à-dire 0.12 et 0.67 µg/L de tamoxifen. Ces molécules ont induit des effets inhabituels tels que la production de : nouveau-nés anormaux, avec des antennes et des queues déformées, des prématurés et des oeufs avortés. Le tamoxifen fut la molécule la plus toxique pour les D. pulex suivie du 4OHTam, de l'endoxifen et enfin de l'imatinib. Lors des expériences sur plusieurs générations, les concentrations n'ayant statistiquement pas d'effet (c.à.d. NOEC en anglais) sur la taille, la reproduction et la croissance intrinsèque de la population étaient du même ordre de grandeur que les concentrations environnementales du tamoxifen. Par exemple, les NOECs du tamoxifen calculées pour la reproduction étaient de 0.67 et 0.72 µg/L, tandis que celle calculée sur la base des anomalies chez les nouveau-nés était < 0.15 µg/L. Les NOECs du 4OHTam se situaient entre 0.16 et 1.48 µg/L et celles de l'endoxifen pour la croissance intrinsèque de la population, ainsi que pour la reproduction, étaient de 0.4 et 4.3 µg/L, respectivement. Dans l'expérience basée sur la récupération des daphnies, la taille et la reproduction ont diminué bien que la descendance fût placée dans un milieu sans substances chimiques. Les daphnies exposées au mélange de tamoxifen et de 4OHTam ont produit moins de nouveau-nés que les contrôles, alors que ces concentrations n'ont pas induit d'effets lorsque testées individuellement. Finalement, l'imatinib n'a pas montré d'effets sur les deux générations testées. Seule la première génération exposée à la plus haute concentration (626 µg/L) a montré une diminution de la reproduction. Les résultats obtenus lors de l'évaluation de la stabilité du tamoxifen, 4OHTam et endoxifen dans le milieu des daphnies ont souligné l'importance d'utiliser des concentrations mesurées ou prédites en écotoxicologie. En effet, des différences notables entre concentrations nominales et mesurées ont été observées à toutes les concentrations et l'hypothèse d'un phénomène d'adsorption sur le verre des récipients a été posée. De ce fait, il a été nécessaire d'élaborer une méthode prédictive efficace et acceptable, en terme de temps et de coûts. Une régression polynomiale basée sur des concentrations mesurées et nominales a permis de prédire avec efficacité les faibles niveaux d'exposition utilisés lors d'expériences écotoxicologiques à long terme, sur plusieurs générations. Suite aux expériences d'écotoxicoprotéomiques, un total de 3940 protéines ont été identifiées et quantifiées chez des daphnies exposées au tamoxifen. Ce nombre est actuellement la plus large série de données publiées et mises à disposition pour la communauté scientifique. Parmi ces protéines, 189 sont significatives et possiblement reliées à des processus de reproduction et de stress. Sur cette base, nous avons émis l'hypothèse que les individus subissant un stress, lié à l'exposition au tamoxifen, ont utilisé leur énergie de base pour favoriser leur survie plutôt que la reproduction. Enfin, la détermination de bio-marqueurs exprimant des dommages précoces des daphnies exposées au tamoxifen n'a pas abouti en tant que telle, mais des protéines prometteuses, telle que la famille de viellogenin-2 (E9H8K5) et le récepteur à la ryanodine (E9FTU9), ont été exprimées après deux jours d'exposition déjà. Ces protéines pourraient faire l'objet d'investigations écotoxicoprotéomiques futures. Les résultats de cette thèse posent certaines questions quant au risque du tamoxifen, du 4OHTam et de l'endoxifen sur la faune et la flore aquatique et plus particulièrement sur les anticancéreux présents dans l'environnement. Les effets toxiques de ces molécules ont été observés à des concentrations environnementales et sur plusieurs générations. La question de considérer les métabolites, et ainsi les pro-médicaments, en écotoxicologie est soulevée, notamment parce que ces molécules peuvent être plus actives et efficaces que la molécule mère. Les expériences chroniques, sur plusieurs générations sont également à favoriser car elles offrent un meilleur reflet de la réalité environnementale que des essais aigus ou d'une génération. L'utilisation de la protéomique permet d'agrandir les connaissances sur les effets des médicaments à un niveau inférieur de l'organisation biologique et ainsi, de mieux comprendre de potentiels mécanismes d'action ou de déterminer de potentiels biomarqueurs. Finalement, il semble important de discuter de l'opportunité de mesurer les concentrations qui sont testées en écotoxicologie afin de ne pas sous-estimer le risque pour la faune et la flore aquatique.

Accurate and efficient simulation of multiphase flow in a heterogeneous reservoir by using error estimate and control in the multiscale finite-volume framework

The multiscale finite-volume (MSFV) method is designed to reduce the computational cost of elliptic and parabolic problems with highly heterogeneous anisotropic coefficients. The reduction is achieved by splitting the original global problem into a set of local problems (with approximate local boundary conditions) coupled by a coarse global problem. It has been shown recently that the numerical errors in MSFV results can be reduced systematically with an iterative procedure that provides a conservative velocity field after any iteration step. The iterative MSFV (i-MSFV) method can be obtained with an improved (smoothed) multiscale solution to enhance the localization conditions, with a Krylov subspace method [e.g., the generalized-minimal-residual (GMRES) algorithm] preconditioned by the MSFV system, or with a combination of both. In a multiphase-flow system, a balance between accuracy and computational efficiency should be achieved by finding a minimum number of i-MSFV iterations (on pressure), which is necessary to achieve the desired accuracy in the saturation solution. In this work, we extend the i-MSFV method to sequential implicit simulation of time-dependent problems. To control the error of the coupled saturation/pressure system, we analyze the transport error caused by an approximate velocity field. We then propose an error-control strategy on the basis of the residual of the pressure equation. At the beginning of simulation, the pressure solution is iterated until a specified accuracy is achieved. To minimize the number of iterations in a multiphase-flow problem, the solution at the previous timestep is used to improve the localization assumption at the current timestep. Additional iterations are used only when the residual becomes larger than a specified threshold value. Numerical results show that only a few iterations on average are necessary to improve the MSFV results significantly, even for very challenging problems. Therefore, the proposed adaptive strategy yields efficient and accurate simulation of multiphase flow in heterogeneous porous media.