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Principal Stratification Designs to Estimate Input Data Missing Due to Death Nous nous intéressons à des études portant sur des cohortes d'individus après la survenue d'un événement critique, comme une blessure, et ayant les caractéristiques suivantes. Premièrement, les études sont conçues pour mesurer des variables d'“input”, qui décrivent la période avant l'événement critique, et pour caractériser la distribution des variables d'“input” dans la cohorte. Deuxièmement, les études sont conçues pour mesurer des variables d'“output”, principalement la mortalité après l'événement critique et pour caractériser la distribution prédictive (conditionnelle) de la mortalité connaissant les variables d'“input” dans la cohorte. De telles études présentent souvent la complication que les données d'“input” manquent pour ceux qui meurent peu après l'événement critique car le recueil des données est réalisé après l'événement. Les méthodes standard de prise en compte des “inputs” manquants, telles que les méthodes d'imputation ou de pondération basées sur l'hypothèse que l'on peut ignorer le processus de données manquantes, sont connues comme étant en général non valides quand le processus de données manquantes ne peut être ignoré, c'est à dire quand la distribution des “inputs” est différente chez ceux qui meurent et ceux qui survivent. Pour répondre à ce problème, nous proposons un nouveau schéma qui recueille et utilise l'information sur une autre variable importante—un traitement ou une variable sous contrôle externe, qui, si elle avait étéà son niveau optimal aurait pu empêcher le décès de ceux qui sont morts. Nous montrons que ce nouveau schéma peut être utilisé pour faire des inférences valides pour la distribution marginale des “inputs” dans la cohorte entière et pour la distribution conditionnelle de la mortalité connaissant les “inputs”, également dans la cohorte entière, même si le processus de données manquante ne peut être ignoré. Le contexte crucial que nous utilisons est la stratification principale basée sur les “outputs” potentiels, comme ici la mortalité après les deux niveaux de traitement. Nous montrons aussi à l'aide de données préliminaires sur des blessures, que notre approche peut donner des résultats qui sont plus raisonnables que les résultats obtenus par les méthodes standard, et ceci de façon relativement dramatique. Ainsi notre approche suggère que le recueil en routine de données sur des variables qui pourraient être utilisées comme traitement possible dans de telles études d'“inputs” et de mortalité devrait être fait en routine. [ABSTRACT FROM AUTHOR]

645 La biologie informatique est un domaine d'évolution rapide, dans lequel les méthodologies provenant de l'informatique, des mathématiques et des statistiques sont appliquées pour traiter les problèmes fondamentaux de la biologie. L'étude de l'information de régulation des gènes est un problème au centre de l'informatique biologique. Cet article rassemble les développements récents de méthodes statistiques liées à ce thème. Partant de la sélection de puces génétiques, nous examinons les méthodes de recherche des éléments de liaison et des modules cis-régulés des facteurs de transcription dans les gènes co-régulés, ainsi que les méthodes pour l'utilisation de l'information des comparaisons croisant les espèces et des expériences ChIP-chip. La meilleure compréhension de la logique de cis-régulation dans le génôme des mammifères peut nécessiter l'information provenant de ces étapes. 691 Les modèles de capture-recapture ont été développés pour estimer la survie à partir de données provenant du marquage et de la surveillance d'animaux sauvages dans le temps. Les différences de survie peuvent être expliquées en incluant des covariables appropriées. Nous proposons des méthodes de régression non-paramétrique et semi-paramétrique pour estimer la survie dans les modèles de capture-recapture. Une approche totalement bayésienne utilisant des simulations MCMC est utilisée pour estimer les paramètres du modèle. Ce travail est illustré par une étude de Pétrels des neiges, dans laquelle les probabilités de survie sont exprimées comme fonctions non-linéaires d'une covariable de climat, en utilisant des données d'une étude de 40 ans d'observation sur des animaux marqués, nichant sur l'île des Pétrels en Terre Adélie. [ABSTRACT FROM AUTHOR]

664 Les plans adaptatifs permettent, en cours d'étude, de modifier le plan d'expérience initial de façon importante. La taille de l'échantillon, en particulier, peut être réévaluée au vu de données intermédiaires ou d'informations extérieures à l'essai. Dans les plans adaptatifs standard, on associe ces modifications à un test pondéré qui garantit le contrôle de l'erreur de première espèce. Cette méthode, cependant, viole des principes de base de la statistique inférentielle. C'est ainsi que, dans un exemple portant sur des données indépendantes issues de la loi normale N(μ, 1), un test adaptatif peut rejeter l'hypothèse nulle μ≤ 0, alors même que la moyenne des observations est négative. Nous en concluons que les plans adaptatifs, au moins dans leur forme la plus générale où l'on recourt à un test pondéré, ne sont pas valides. Nous discutons plusieurs modifications possibles de cette méthodologie des plans adaptatifs, en nous concentrant sur la recherche de solutions satisfaisantes quant aux tests d'hypothèses. [ABSTRACT FROM AUTHOR]

This paper deals with an optimization problem of determining the maintenance units and age‐based inspection schemes to minimize the expected maintenance cost rate and satisfy a target system availability for multi‐indenture systems that have a modular structure with redundant units. Failures of primary components directly lead to system failures and can therefore be identified and maintained immediately, while failures of redundant components need to be identified by inspections. And the designated maintenance units need to be replaced during maintenance. By constructing the dual structure of the fault tree, we present a failure path enumeration method, based on which the system availability and expected maintenance cost rate models considering maintenance time are derived. For redundant units, two types of inspection policies are considered in our models: one is the corrective maintenance (CM)‐based inspection policy, and the other one is the age‐based inspection (PM) policy, inspections are performed at failures or age h, depending on which occurred earlier. A heuristic algorithm is proposed to find the reasonable maintenance units and inspection intervals simultaneously, and its performance is also compared and analyzed. Several numerical examples are studied to investigate the effect of parameters on optimal solutions. [ABSTRACT FROM AUTHOR]

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Copyright of African Development Review / Revue Africaine de Développement is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Cet article analyse les effets de l'exploitation des ressources naturelles sur les recettes fiscales non liées aux ressources naturelles dans les pays de l'Union Economique et Monétaire Ouest Africaine (UEMOA) de 1996 à 2015 en utilisant les Effets Fixes Dynamiques (Dynamic Fixed Effects, DFE). Les résultats montrent que l'exploitation des ressources naturelles dissuade la mobilisation des recettes fiscales non liées aux ressources naturelles. La mauvaise qualité des institutions amplifie l'effet corrosif. Les résultats restent stables suivant les différents indicateurs de la qualité institutionnelle et les types de ressources naturelles. Ces résultats impliquent que les pays de l'UEMOA doivent améliorer la qualité des institutions de sorte à accroître leur capacité à gérer d'importants revenus provenant des ressources naturelles. [ABSTRACT FROM AUTHOR]

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Copyright of Mathematika is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Revue Internationale du Travail is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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The main results available on the use of black-and-white Petri nets for modelling, planning and scheduling manufacturing systems are presented. In the first part of the paper, the basics of Petri nets necessary to understand the subsequent presentation are introduced. Particular attention is paid to event graphs, a particular type of Petri nets used for modelling and evaluating ratio-driven systems. The second part of the paper is devoted to ratio-driven systems, their modelling and their scheduling. Job-shops, assembly systems, and KANBAN systems are used to illustrate this section. Finally, the general case is investigated of manufacturing systems subject to changing demands. An approach based on conflict-free Petri nets with input and output transitions is proposed for planning and scheduling this type of system. [ABSTRACT FROM AUTHOR]

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The complexes of poly A and poly U are interesting models for studying the structure of nucleic acids. In the first part of this paper, the thermal stability of these complexes has been studied as a function of both pH and ionic strength in alkaline solution. The thermal stability is measured by the half transition temperatures, or Tm's. There are four different kinds of transitions: Tm2-1 refers to the dissociation of the two-stranded complex, poly (A + U); Tm2-1 to the dissociation of the three-stranded complex, poly (A + 2U) [4]. Tm8-2 is the temperature of half dissociation of poly (A + 2U) into poly (A + U) [1], and Tm2-3 is the temperature of rearrangement of 2 poly (A + U) into poly (A + 2U) [3] (Fig. 1). It is found that Tm2-1, and Tm8-1 decrease as pH increases above neutrality (Fig. 2 and 3), but that Tm2-8 does not vary (Fig. 3). This effect is readily explained if it is assumed that the ionisation of uracil brings a change in the state of the free poly U, but that the complexes themselves are not modified. In the second part of the paper a simple thermodynamic formulation is given which represents satisfactorily the relationship between the four equilibria, as observed at neutral pH (Fig. 1). A more complex treatment is then presented. It includes quantitation of electrostatic interactions, according to the theory of Kotin [18] and of the free enthalpy term corresponding to the organisation (stacking) of poly A. This leads to an excellent representation of the experimental data (Fig. 5). In alkaline solution, one can calculate the free enthalpy change associated with the ionisation of poly U at the Tm. According to our observations, it is likely that this is the only factor responsible for the decrease of Tm. Therefore, we can write that the sum of the free enthalpy of complex formation in the same conditions, but at pH 7, and of the free enthalpy of ionisation is zero. This leads to a determination of ΔG both as a function of temperature and ionic strength: the variation of ΔG with these factors is shown to be in good agreement with our detailed model. However, the absolute values are different, probably because of uncertainties concerning the data for poly A stacking enthalpy and entropy. Apart from providing evaluation of the thermodynamic parameters for double and triple helix formation, our results lead us to emphasize the importance of the thermodynamic state of the unassociated polynucleotides. This may be particularly relevant when one considers the partially complementary secondary structures of RNA's. [ABSTRACT FROM AUTHOR]

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The implementation of climate change adaptation polices has barely occurred in developed countries. This paper examines to what extent the perceptions of political actors might hinder the development of adaptation policies. We study the Swiss case using computer aided textual analysis. Our results demonstrate that adaptation is still not perceived as an important dimension of climate change policy. Decision makers do not perceive links between adaptation, the Swiss economy and the energy supply. Adaptation is mainly considered an issue .for developing countries and not as a way to reduce the impacts of climate change in Switzerland. Right-wing parties tend to consider adaptation a secondary issue and are more likely than those to the left to object to the formulation or the implementation of public measures. [ABSTRACT FROM AUTHOR]

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Close to the monumental graves, numerous ancient wells, some of which reach a depth of 18 m, were found in the Nabatean site of Mad in āli . Their fascinating study was begun by the author, a well-known speleologist. It required a geomorphological and hydrological approach of the site which established the groundwater level and piezometric contours. Furthermore, research was conducted on the palaeoclimates and present-day pluviometry, which has concluded that the fall in the groundwater level since antiquity is mainly the result of modern exploitation. Since 1975 the high-yielding submerged pumps have provided intensive irrigation to the important agriculture of el Hijr, close to the Nabatean site. The wells, their construction, their shape and ancient mechanism are described in this paper. [ABSTRACT FROM AUTHOR]

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Copyright of Canadian Geographer is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of African Development Review / Revue Africaine de Développement is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tropical Medicine & International Health is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An n‐affine manifold is a differentiable manifold endowed with an atlas whose transition functions are locally affine transformations of ℝn. The paper studies affine dynamic, that is, affine endomorphisms of affine manifolds. The main goal is to relate the dynamical viewpoint to the completeness problem. In particular, it is shown that the Markus conjecture is true when dim Aff(M,ᐁ) > dim M − 2. [ABSTRACT FROM PUBLISHER]

Résumé: Les auteurs s'interrogent sur la validité de la loi d'Okun en Amérique latine. En s'appuyant sur plusieurs modèles économétriques, ils montrent que, dans la région, les fluctuations de l'activité économique influent moins sur les taux de chômage que dans les économies plus avancées, et que la relation chômage/production varie selon le pays. Cependant, même quand la relation d'Okun est faible ou inexistante, les variations cycliques nuisent à la qualité de l'emploi. Ces observations plaident pour l'adoption de mesures de lutte contre le chômage non plus générales mais ciblées sur des branches spécifiques, ainsi que pour une action en faveur de la qualité de l'emploi. [ABSTRACT FROM AUTHOR]

Résumé: Selon l'approche «insiders‐outsiders», qui domine le discours sur le droit du travail, la législation protectrice de l'emploi favorise les travailleurs dotés d'un emploi stable, les insiders, au détriment des outsiders, moins bien lotis. Les outsiders devraient de ce fait être favorables à la déréglementation. Les auteurs observent pourtant que, dans les pays en développement, ceux‐ci sont au contraire très majoritairement attachés à la protection de l'emploi. Ils plaident donc pour une remise en question de l'opposition traditionnelle entre insiders et outsiders et pour une meilleure prise en compte d'aspects comme la mutualisation des gains, les transitions professionnelles, l'équité ou le pouvoir de l'employeur. [ABSTRACT FROM AUTHOR]

Résumé: L'autrice cherche à mesurer l'impact des événements de vie sur le capital‐vieillesse dans le contexte du Chili, où le régime de prévoyance repose sur des comptes d'épargne individuels obligatoires. Cet impact empruntant des canaux multiples, elle utilise un système d'équations corrélées, qui rendent compte du comportement d'activité, du choix du fonds de pension, des décisions d'épargne, de la propension au risque, de la situation familiale et de l'état de santé. L'analyse montre que les problèmes de santé n'ont pas d'effet sexué sur la retraite, contrairement aux chocs liés aux caractéristiques familiales, qui ont un impact plus important pour les femmes que pour les hommes. [ABSTRACT FROM AUTHOR]

Résumé: Les auteurs cherchent à déterminer dans quelle mesure le travail temporaire fonctionne comme un tremplin vers l'emploi permanent, en distinguant les transitions intra‐entreprises et interentreprises. Pour cela, ils s'appuient sur une base de données employeurs‐salariés recueillies au Pérou sur la période 2012‐2016. Ils proposent plusieurs mesures de ces transitions et estiment des modèles de durée. Ils montrent que seuls 7 pour cent des contrats à durée déterminée sont suivis d'un contrat à durée indéterminée. Ces conversions relèvent d'une mobilité intra‐entreprise dans environ la moitié des cas. [ABSTRACT FROM AUTHOR]

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Copyright of Revue Internationale du Travail is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue Internationale du Travail is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes the French enlarged system of national accounts, and discusses its relevance for the revision of the UN System of National Accounts. Part I develops the concept of a "Central System" of national accounts, and sets out its minimum requirements and the margins as within which adjustments or variants would be acceptable. This part concludes that the Central System is the basic system of macro-economics, and must meet the needs of macro-economists both as to content and coherence. Part II discusses the issue of the complexity of SNA. It proposes the introduction of a "tableau economique d'ensemble" (TEE) to provide an overview of the Central System, and shows how certain complementary approaches dealing with population, employment, input-output, financial operations, and more detailed presentations of wealth accounts and institutional sector accounts can be related to the TEE. The third part discusses the possibilities of deriving directly the accounts of the Central System from microdata for individual units, concluding that although this may be possible in limited special cases such as central government, it is generally impractical. For certain sectors--especially non-financial corporate and quasi-corporate enterprises--a system of intermediate accounts is proposed, which would reflect the data that can be collected from these units without adjustments and/or corrections needed for the national accounts. For other sectors, notably households, only global treatment seems feasible. Part IV introduces the concept of satellite accounts as a means of extending the coverage of the data system without overburdening the Central System. Annexes illustrate the tableau economique d'ensemble, the intermediate accounts, satellite accounts, and accounts relating to such extensions as natural resources and the ecosystem. [ABSTRACT FROM AUTHOR]

Subepidermal cells of thin tissue pieces with a few cell layers were capable of forming either buds, roots, (lowers or non-organogenetic callus. To determine whether this callus is able to differentiate into organs, we transferred it to media inducing either flowers, or buds, or roots. In this paper, we study the capacity of the callus to form buds. In 50% of the cases, the explants (being maintained for 1 day to 2 years in callus media) can still express the capacity to form buds. This percentage increased with increased agar concentration of the culture media. At the histological level, non-organogenetic callus is characterized by the absence of tracheid differentiation, whereas in the organogenetic callus, tracheids were induced after their transfer into a 'Bud medium' and indicate an organogenetic differentiation pattern. [ABSTRACT FROM AUTHOR]

A spectrophotometric technique after paper chromatography was found adequate for quantitatively determining chlorogenic and caffeic acids in the vegetative apical buds of Pyrus communis L., variety ‘Passe‐Crassane’, de ľOrléanais. Using this method, significant changes in these polyphenols were shown to occur both in tissue concentration and total amount per bud, in samples collected during winter 1973–1974. A close relationship between chlorogenic acid concentration and state of dormancy of excised twigs was found. [ABSTRACT FROM AUTHOR]

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Copyright of Canadian Public Administration is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)