University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

Accelerated Life Models: Modeling and Statistical Analysis

Abstract: Failure Time Distributions Introduction Parametric Classes of Failure Time Distributions Accelerated Life Models Introduction Generalized Sedyakin's Model Accelerated Failure Time Model Proportional Hazards Model Generalized Proportional Hazards Models Generalized Additive and Additive-Multiplicative Hazards Models Changing Shape and Scale Models Generalizations Models Including Switch-Up and Cycling Effects Heredity Hypothesis Summary Accelerated Degradation Models Introduction Degradation Models Modeling the Influence of Explanatory Variables on Degradation Modeling the Traumatic Event Process Maximum Likelihood Estimation for FTR Data Censored Failure Time Data Parametric Likelihood Function for Right Censored FTR Data Score Function Asymptotic Properties of the Maximum Likelihood Estimators Approximate Confidence Intervals Some Remarks on Semi-Parametric Estimation AFT Model: Parametric FTR and ALT Data Analysis Parametrization of the AFT Model Interpretation of the Regression Coefficients FTR Data Analysis: Scale-Shape Families of Distributions FTR Data Analysis: Generalized Weibull Distribution FTR Data Analysis: Exponential Distribution Plans of Experiments in Accelerated Life Testing Parametric Estimation in ALT Under the AFT Model AFT Models: Semi-Parametric FTR and AFT Data Analysis FTR Data Analysis Semi-Parametric Estimation in ALT PH Model: Semi-Parametric FTR Data Analysis Introduction Parametrization of the PH Model Interpretation of the Regression Coefficients Semi-Parametric FTR Data Analysis for the PH Model GPH Models: FTR Analysis Introduction Semi-Parametric FTR Data Analysis for the GPH1 Models Semi-Parametric FTR Data Analysis: Intersecting Hazards Changing Scale and Shape Model Parametric FTR Data Analysis Semi-Parametric FTR Data Analysis Semi-Parametric Estimation in ALT GAH and GAMH Model: Semi-Parametric FTR and ALT Data Analysis GAH Model GAMH Model AAR Model PPAR Model Estimation When a Process of Production in Unstable Application of the AFT Model Application of the GPH1 Model Goodness-of-Fit for Accelerated Life Models Goodness-of-Fit for the GS Model Goodness-of-Fit for the Model with Absence of Memory Goodness-of-Fit for the AFT Model Goodness-of-Fit for the PH Model Goodness-of-Fit for the GPH Models Goodness-of-Fit for the Parametric Regression Models Estimation in Degradation Models with Explanatory Variables Introduction Linear Path Models Gamma and Shock Processes Some Results from Stochastic Process Theory Stochastic Process. Filtration Counting Process Stochastic Integral Conditional Expectation Martingale Predictable Process and Doob-Meyer Decomposition Predictable Variation and Predictable Covariation Stochastic Integrals with Respect to Martingales Localization Stochastic Integrals with Respect to Martingales (continuation) Weak Convergence Central Limit Theorem for Martingales Non-Parametric Estimators of the Cumulative Hazard and the Survival Function Product-Integral Delta Method References

The timing of the last deglaciation in North Atlantic climate records

Abstract: To determine the mechanisms governing the last deglaciation and the sequence of events that lead to deglaciation, it is important to obtain a temporal framework that applies to both continental and marine climate records. Radiocarbon dating has been widely used to derive calendar dates for marine sediments, but it rests on the assumption that the ‘apparent age’ of surface water (the age of surface water relative to the atmosphere) has remained constant over time1,2. Here we present new evidence for variation in the apparent age of surface water (or reservoir age) in the North Atlantic ocean north of 40° N over the past 20,000 years. In two cores we found apparent surface-water ages to be larger than those of today by 1,230 ± 600 and 1,940 ± 750 years at the end of the Heinrich 1 surge event (15,000 years BP) and by 820 ± 430 to 1,010 ± 340 years at the end of the Younger Dryas cold episode. During the warm Bolling–Allerod period, between these two periods of large reservoir ages, apparent surface-water ages were comparable to present values. Our results allow us to reconcile the chronologies from ice cores and the North Atlantic marine records over the entire deglaciation period. Moreover, the data imply that marine carbon dates from the North Atlantic north of 40° N will need to be corrected for these highly variable effects.

Characterization and Biological Function of the ISOCHORISMATE SYNTHASE2 Gene of Arabidopsis

Abstract: Salicylic acid (SA) is an important mediator of plant defense response. In Arabidopsis (Arabidopsis thaliana), this compound was proposed to derive mainly from isochorismate, itself produced from chorismate through the activity of ISOCHORISMATE SYNTHASE1 (ICS1). Null ics1 mutants still accumulate some SA, suggesting the existence of an enzymatic activity redundant with ICS1 or of an alternative ICS-independent SA biosynthetic route. Here, we studied the role of ICS2, a second ICS gene of the Arabidopsis genome, in the production of SA. We have shown that ICS2 encodes a functional ICS enzyme and that, similar to ICS1, ICS2 is targeted to the plastids. Comparison of SA accumulation in the ics1, ics2, and ics1 ics2 mutants indicates that ICS2 participates in the synthesis of SA, but in limited amounts that become clearly detectable only when ICS1 is lacking. This unequal redundancy relationship was also observed for phylloquinone, another isochorismate-derived end product. Furthermore, detection of SA in the double ics1 ics2 double mutant that is completely devoid of phylloquinone provides genetic evidence of the existence of an ICS-independent SA biosynthetic pathway in Arabidopsis.

The interplay of landscape composition and configuration: new pathways to manage functional biodiversity and agroecosystem services across Europe

Abstract: Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and non-crop habitats, and species’ dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. Overall, however, in landscapes with high edge density, 70% of pollinator and 44% of natural enemy species reached highest abundances and pollination and pest control improved 1.7- and 1.4-fold respectively. Arable-dominated landscapes with high edge densities achieved high yields. This suggests that enhancing edge density in European agroecosystems can promote functional biodiversity and yield-enhancing ecosystem services.

Why is letter-name knowledge such a good predictor of learning to read?

Abstract: The knowledge of letter names measured just before children enter school has been known for a long time as one of the best longitudinal predictors of learning to read in an alphabetic writing system. After a period during which the comprehensive investigation of this relationship was largely disregarded, there is now a growing interest in attempts to understand the role(s) letter names play in literacy acquisition. This paper reviews these recent studies and emphasizes their main findings regarding the influence of letter-name knowledge in early and formal literacy for three main components of literacy acquisition: first, the emergence of the phonological processing of print; then, the learning of letter-sound correspondences; finally, the development of phonemic sensitivity skills. The final section discusses the status of letter-name knowledge (LNK) in literacy acquisition and suggests possible directions for further research.