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- PublicationMétadonnées seulementGender Wage Inequalities in Switzerland: the Public versus the Private Sector(2017-9-19)
; Wage differences between women and men can be divided into an explained part and an unexplained part. The former encompasses differences in the observable characteristics of the members of groups, such as age, education or work experience. The latter includes the part of the difference that is not attributable to objective factors and represents an estimation of the discrimination level. We discuss the original method of Blinder (J Hum Resour 8(4):436–455, 1973) and Oaxaca (Int Econ Rev 14(3):693–709, 1973), the reweighting technique of DiNardo et al. (Econometrica 64(5):1001–1044, 1996) and our approach based on calibration. Using a Swiss dataset from 2012, we compare the estimated explained and unexplained parts of the difference in average wages in the private and public sectors obtained with the three methods. We show that for the private sector, all three methods yield similar results. For the public sector, the reweighting technique estimates a lower value of the unexplained part than the other two methods. The calibration approach and the reweighting technique allow us to estimate the explained and unexplained parts of the wage differences at points other than the mean. By using this, in this paper, the assumption that wages are more equitable in the public sector is analysed. Wage differences at different quantiles in both sectors are examined. We show that in the public sector, discrimination occurs quite uniformly both in lower and in higher-paying jobs. On the other hand, in the private sector, discrimination is greater in lower-paying jobs than in higher-paying jobs.queryPlease check and confirm the given name and family name is correctly identified for the first author and amend if necessary. - PublicationMétadonnées seulement
- PublicationMétadonnées seulementCrab spiders impact floral-signal evolution indirectly through removal of florivores(2018-4-10)
; Schiestl, Florian PThe puzzling diversity of flowers is primarily shaped by selection and evolutionary change caused by the plant’s interaction with animals. The contribution of individual animal species to net selection, however, may vary depending on the network of interacting organisms. Here we document that in the buckler mustard, Biscutella laevigata, the crab spider Thomisus onustus reduces bee visits to flowers but also benefits plants by feeding on florivores. Uninfested plants experience a trade-off between pollinator and spider attraction as both bees and crab spiders are attracted by the floral volatile β-ocimene. This trade-off is reduced by the induced emission of β-ocimene after florivore infestation, which is stronger in plant populations where crab spiders are present than where they are absent, suggesting that plants are locally adapted to the presence of crab spiders. Our study demonstrates the context-dependence of selection and shows how crab spiders impact on floral evolution. - PublicationMétadonnées seulementMultiresolution Approach to Condition Categorical Multiple-Point Realizations to Dynamic Data With Iterative Ensemble Smoothing(2023-1-19)
; ; A new methodology is presented for the conditioning of categorical multiple-point statistics (MPS) simulations to dynamic data with an iterative ensemble smoother (ES-MDA). The methodology relies on a novel multiresolution parameterization of the categorical MPS simulation. The ensemble of latent parameters is initially defined on the basis of the coarsest-resolution simulations of an ensemble of multiresolution MPS simulations. Because this ensemble is non-multi-Gaussian, additional steps prior to the computation of the first update are proposed. In particular, the parameters are updated at predefined locations at the coarsest scale and integrated as hard data to generate a new multiresolution MPS simulation. The performance of the methodology was assessed on a synthetic groundwater flow problem inspired from a real situation. The results illustrate that the method converges towards a set of final categorical realizations that are consistent with the initial categorical ensemble. The convergence is reliable in the sense that it is fully controlled by the integration of the ES-MDA update into the new conditional multiresolution MPS simulations. Thanks to a massively reduced number of parameters compared to the size of the categorical simulation, the identification of the geological structures during the data assimilation is particularly efficient for this example. The comparison between the estimated uncertainty and a reference estimate obtained with a Monte Carlo method shows that the uncertainty is not severely reduced during the assimilation as is often the case. The connectivity is successfully reproduced during the iterative procedure despite the rather large distance between the observation points. - PublicationAccès libreConditioning groundwater flow parameters with iterative ensemble smoothers: analysis and approaches in the continuous and the discrete cases(2020)
; ; L’assimilation de données consiste à combiner de façon optimale les observations (données) et les prévisions produites par un modèle numérique d’un système dynamique étudié. Au cours de la dernière décennie, les méthodes basées sur le filtre de Kalman d’ensemble (EnKF) pour l’assimilation de données ont été particulièrement explorées dans diverses disciplines des géosciences pour résoudre des problèmes inverses. Bien que ces méthodes d’ensemble aient été développées afin de pouvoir traiter efficacement des problèmes de grandes dimensions, elles supposent que les erreurs qui affectent les observations et le modèle suivent une loi de distribution Gaussienne multivariée. Pour traiter de potentielles nonlinéarités entre les données et les variables paramètres ou d’état que l’on souhaite conditionner, des variantes itératives de méthodes existantes ont été proposées. Dans cette thèse, nous nous intéressons dans un premier temps à la performance de deux principales méthodes de lisseur d’ensemble itératif pour le calage d’un modèle synthétique d’écoulement souterrain 2D. A partir du même jeu de données ponctuelles (locales) et transitoires (dynamiques), nous analysons la performance de chaque méthode pour le conditionnement d’un ensemble de champs multi-Gaussiens de valeurs de conductivité hydraulique. Nous explorons ensuite plus particulièrement l’application d’une des méthodes, ES-MDA, dans des situations plus ou moins complexes suivant la méthode de simulation géostatistique employée pour représenter l’information géologique a priori. Nous évaluons tout d’abord la pertinence d’une paramétrisation basée sur une transformation normal-score dans un cas non-multi-Gaussien. La robustesse de la méthode d’ensemble face aux nonlinéarités est ensuite plus particulièrement testée dans le cas de réalisations de variables discrètes de facies géologique obtenues par la technique des gaussiennes tronquées et mises à jour via leurs variables continues sous-jacentes. En nous basant sur les limitations et avantages observées expérimentalement pour les paramétrisations précédemment évoquées, nous proposons finalement une nouvelle méthodologie d’assimilation de données dynamiques. Bien qu’elle implique une méthode classique de Kalman d’ensemble, la méthodologie proposée permet spécifiquement le conditionnement de champs de facies géologiques, soit de variables discrètes, qui sont initialement simulés par statistiques à points multiples (MPS). Cette méthodologie s’appuie sur une paramétrisation multi-résolutions nouvelle de la simulation MPS catégorique où, l’ensemble de paramètres latents est défini initialement à partir des simulations à l’échelle la plus grossière d’un ensemble de simulations MPS multi-résolutions. Comme cet ensemble n’est pas multi-Gaussien, des étapes additionnelles précédant le calcul de la première correction sont proposées. Notamment, les paramètres sont corrigés à des points prédéfinis à l’échelle la plus grossière, puis intégrés en tant que données de conditionnement pour générer une nouvelle simulation MPS multi-résolutions. Les résultats obtenus sur le problème synthétique montrent que la méthode converge vers un ensemble de réalisations catégoriques finales cohérent avec l’ensemble catégorique initial. La convergence est fiable en ce sens qu’elle est contrôlée entièrement par l’intégration de la correction de ES-MDA dans les nouvelles simulations MPS multi-résolutions conditionnelles. De plus, grâce à la paramétrisation proposée, l’identification des structures géologiques durant l’assimilation des données est particulièrement efficace pour cet exemple. La comparaison entre l’incertitude estimée et une estimation de référence obtenue avec une méthode de Monte-Carlo révèle que l’incertitude n’est pas sévèrement réduite durant l’assimilation comme cela est souvent observé. La connectivité des structures est bien reproduite durant la procédure itérative malgré la distance plutôt élevée entre les points d’observation., Data assimilation (DA) consists in combining observations and predictions of a numerical model to produce an optimal estimate of the evolving state of a system. Over the last decade, DA methods based on the Ensemble Kalman Filter (EnKF) have been particularly explored in various geoscience fields for inverse modelling. Although this type of ensemble methods can handle high-dimensional systems, they assume that the errors coming from whether the observations or the numerical model are multi-Gaussian. To handle potential nonlinearities between the observations and the state or parameter variables to estimate, iterative variants have been proposed. In this thesis, we first focus on two main iterative ensemble smoother methods for the calibration of a synthetic 2D groundwater model. Using the same set of sparse and transient flow data, we analyse each method when employing them to condition an ensemble of multi-Gaussian hydraulic conductivity fields. We then further explore the application of one iterative ensemble smoother algorithm (ES-MDA) in situations of variable complexity, depending on the geostatistical simulation method used to simulate the prior geological information. The applicability of a parameterization based on the normal-score transform is first investigated. The robustness of the method against nonlinearities is then further explored in the case of discrete facies realizations obtained with a truncated Gaussian technique and updated via their underlying continuous variables. Based on the observed limitations and benefits of the forementioned parameterizations, we finally propose a new methodology for the conditioning of categorical multiple-point statistics (MPS) simulations to dynamic data with a state-of-the-art ensemble Kalman method by taking the example of the Ensemble Smoother with Multiple Data Assimilation (ES-MDA). Our methodology relies on a novel multi-resolution parameterization of the categorical MPS simulation. The ensemble of latent parameters is initially defined on the basis of the coarsest-resolution simulations of an ensemble of multi-resolution MPS simulations. Because this ensemble is non-multi-Gaussian, additional steps prior to the computation of the first update are proposed. In particular, the parameters are updated at predefined locations at the coarsest scale and integrated as hard data to generate a new multi-resolution MPS simulation. The results on the synthetic problem illustrate that the method converges towards a set of final categorical realizations that are consistent with the initial categorical ensemble. The convergence is reliable in the sense that it is fully controlled by the integration of the ES-MDA update into the new conditional multi-resolution MPS simulations. Moreover, thanks to the proposed parameterization, the identification of the geological structures during the data assimilation is particularly efficient for this example. The comparison between the estimated uncertainty and a reference estimate obtained with a Monte Carlo method shows that the uncertainty is not severely reduced during the assimilation as is often the case. The connectivity is successfully reproduced during the iterative procedure despite the rather large distance between the observation points. - PublicationAccès libreUse of the Larval Tarsal Test to determine acaricide resistance in Rhipicephalus (Boophilus) microplus Brazilian field populations(2012-9-10)Acaricide resistance of the cattle tick Rhipicephalus (Boophilus) microplus is widespread in most of the countries where this parasite is present. Bioassays are used to diagnose the level and pattern of resistance in tick populations. In the present study, we describe a detailed protocol of the Larval Tarsal Test (LTT) using simplified equipment and data on the resistance of 17 tick field populations originating from 5 Brazilian states. Nine acaricidal compounds from 5 major classes were tested: organophosphates (OP), synthetic pyrethroids (SP), macrocyclic lactones (ML), phenylpyrazols (PYZ) and amidines. For comparison, four of the tick populations were also tested with the Larval Packet Test (LPT) with one compound per class. The most common resistances were to SP, amitraz and OP, with frequencies of 94%, 88% and 82%, respectively. Resistance to PYZ was also found to be widespread (65%), suggesting a rapid development of fipronil resistance in Brazil. One case of ML resistance and 2 cases of suspected ML resistance were identified with the LTT. The LTT led to higher resistance ratios to all compounds than the LPT, reflecting its high sensitivity to detect resistance. Finally, the LTT allowed testing a larger number of compounds and doses with reduced labour in comparison to the LPT and turned out to be a reliable bioassay to detect resistance in field populations.
- PublicationAccès libreEfficacy of Praziquantel against Schistosoma mekongi and Opisthorchis viverrini: A Randomized, Single- Blinded Dose-Comparison Trial(2012-8-5)Background: Schistosomiasis and opisthorchiasis are of public health importance in Southeast Asia. Praziquantel (PZQ) is the drug of choice for morbidity control but few dose comparisons have been made. Methodology: Ninety-three schoolchildren were enrolled in an area of Lao PDR where Schistosoma mekongi and Opisthorchis viverrini coexist for a PZQ dose-comparison trial. Prevalence and intensity of infections were determined by a rigorous diagnostic effort (3 stool specimens, each examined with triplicate Kato-Katz) before and 28–30 days after treatment. Ninety children with full baseline data were randomized to receive PZQ: the 40 mg/kg standard single dose (n = 45) or a 75 mg/kg total dose (50 mg/kg+25 mg/kg, 4 hours apart; n = 45). Adverse events were assessed at 3 and 24 hours posttreatment. Principal Findings: Baseline infection prevalence of S. mekongi and O. viverrini were 87.8% and 98.9%, respectively. S. mekongi cure rates were 75.0% (95% confidence interval (CI): 56.6–88.5%) and 80.8% (95% CI: 60.6–93.4%) for 40 mg/kg and 75 mg/kg PZQ, respectively (P = 0.60). O. viverrini cure rates were significantly different at 71.4% (95% CI: 53.4–84.4%) and 96.6% (95% CI: not defined), respectively (P = 0.009). Egg reduction rates (ERRs) against O. viverrini were very high for both doses (.99%), but slightly lower for S. mekongi at 40 mg/kg (96.4% vs. 98.1%) and not influenced by increasing diagnostic effort. O. viverrini cure rates would have been overestimated and no statistical difference between doses found if efficacy was based on a minimum sampling effort (single Kato-Katz before and after treatment). Adverse events were common (96%), mainly mild with no significant differences between the two treatment groups. Conclusions/Significance: Cure rate from the 75 mg/kg PZQ dose was more efficacious than 40 mg/kg against O. viverrini but not against S. mekongi infections, while ERRs were similar for both doses.
- PublicationAccès libreDistribution patterns of three sodium channel mutations associated with pyrethroid resistance in Rhipicephalus (Boophilus) microplus populations from North and South America, South Africa and Australia(2012-9-3)Resistance to synthetic pyrethroids (SP) in the cattle tick Rhipicephalus (Boophilus) microplus is widespread throughout its distribution area. Three single nucleotide substitutions identified in Domains II and III of the sodium channel gene of R. (B.) microplus are known to be associated with target site pyrethroid resistance. We developed a multiplex PCR using allele-specific primers to amplify wild type or mutated genotypes of the three mutations simultaneously. This assay was used to screen tick samples originating from Brazil, Argentina, Mexico, South Africa and Australia whose phenotype to flumethrin and cypermethrin had been determined by the use of the Larval Tarsal test (LTT) or the Larval Packet Test (LPT). These mutations were found to have distinct geographical distributions and result in different resistance phenotypes. The L64I Domain II mutation conferring resistance to several SP compounds was found in all the Brazilian, Argentinean and Australian populations and in one South African population, with frequencies between 38% and 100% in flumethrin and cypermethrin resistant populations, respectively. In contrast, this mutation was not found in samples from Mexico, while the Domain III mutation was found exclusively in this country. The G72V Domain II flumethrin-specific mutation was found in a single Australian population, at a very low frequency (6%). The homozygous resistant RR genotype of the L64I Domain II mutation correlated significantly with the survival rates at the discriminating doses of flumethrin and cypermethrin. This survey shows the widespread distribution of the L64I Domain II mutation and provides evidence of its geographic separation from the Domain III mutation.
- PublicationAccès librePCR diagnosis of Opisthorchis viverrini and Haplorchis taichui infections in an endemic Lao community: a comparison of diagnostic methods for parasitological field surveys(2012-11-18)Opisthorchiasis is a major public health problem in Southeast Asia. Affected individuals often have mixed infections with the liver fluke Opisthorchis viverrini and minute intestinal flukes such as Haplorchis taichui. The usual methods of diagnosing these infections involve the demonstration of fluke eggs in stool samples under light microscopy, but sensitivity and specificity are low. We developed two PCR tests that detect and discriminate between O. viverrini and H. taichui infections. PCR tests were validated by stool samples from purged individuals. We then applied the PCR tests to estimate the prevalence of O. viverrini and H. taichui infections from a random sample of individuals selected from an endemic community in Khong District, Laos. PCR results were compared with those from the Kato-Katz (KK) method and the formalin-ether concentration technique (FECT). When validated with purge results, PCR tests of O. viverrini and H. taichui had a sensitivity of 93.7% (95% Confidence Interval (CI): 85.8 to 97.9%) and 73.3% (95% CI: 60.3 to 83.9%) and could detect as low as 0.75 pg DNA and 1.32 ng DNA, respectively. The PCR-determined community prevalence of O. viverrini and H. taichui infections was 63.9% (95% CI: 54.1 to 72.9%) and 30.6% (95% CI: 22.1 to 40.2%), respectively. Using PCR as the gold standard to detect O. viverrini, three KK thick smears performed comparably well whereas one KK smear and FECT were poorer (sensitivity of 91.4% (95% CI: 81.0 to 97.1%), 62.3% (95% CI: 49.8 to 73.7%) and 49.3% (95% CI: 37.0 to 61.6%), respectively). PCR may be a valuable and sensitive diagnostic tool, particularly for low intensity O. viverrini and H. taichui infections.