Search results for "Models"
showing 10 items of 8211 documents
Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions
2018
Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define i…
Typology of exogenous organic matters based on chemical and biochemical composition to predict potential nitrogen mineralization
2010
Our aim was to develop a typology predicting potential N availability of exogenous organic matters (EOMs) in soil based on their chemical characteristics. A database of 273 EOMs was constructed including analytical data of biochemical fractionation, organic C and N, and results of N mineralization during incubation of soil–EOM mixtures in controlled conditions. Multiple factor analysis and hierarchical classification were performed to gather EOMs with similar composition and N mineralization behavior. A typology was then defined using composition criteria to predict potential N mineralization. Six classes of EOM potential N mineralization in soil were defined, from high potential N minerali…
A partial review of cure models with an application to French cancer registries data to improve patients' access to insurance and credit
2016
International audience; BackgroundSurvival cure models are widely used in public health researches to analyze time-to-event data in which some subjects would never experience the event of interest; these subjects are said to be statistically cured. There are two types of cure models, the mixture cure modeland the non-mixture cure model which were first formulated respectively by Boag(1949)[1] and Yakovlev et al. (1993) [2]. These models have been intensively developed [3,4 among others] and have also been extended to the net survival framework [5-7 for instance].In cancersurvival analysis,net survival is a measure of survival in the hypothetical world wherecancer would bethe only possible c…
Modéliser la réponse des espèces marines antarctiques aux changements environnementaux. Méthodes, applications et limites.
2021
Among tools that are used to fill knowledge gaps on natural systems, ecological modelling has been widely applied during the last two decades. Ecological models are simple representations of a complex reality. They allow to highlight environmental drivers of species ecological niche and better understand species responses to environmental changes. However, applying models to Southern Ocean benthic organisms raises several methodological challenges. Species presence datasets are often aggregated in time and space nearby research stations or along main sailing routes. Data are often limited in number to correctly describe species occupied space and physiology. Finally, environmental datasets …
Prognosis of resected intrahepatic cholangiocarcinoma
2017
Introduction. Complete resection stands as the only curative option for intrahepatic cholangiocarcinoma (IHCC). Still, prognosis remains poor after resection due to a recurrence rate over 60% leading to actual 5-year survival rates below 20%. Reliable prognostic estimation and better understanding of tumor biology would be of interest for improving IHCC prognosis.Methods. Using clinical and biological data from two large cohort of resected IHCC (MSKCC, n=189 and AFC, n=522), three objectives have been explored. First, assessing the performances of different published prognostic models. Second, defining the reliability of preoperative prognostic estimation using imaging, tumoral genomic prof…
Analyze and simulation a dynamic of soil indicators fertility under different agricultural management practices in cotton area of Togo
2011
Using data observed during 20 to 40 years in different agro-ecosystems of Togo, we analyzed soil fertility dynamic under different agricultural management practices. Tree soil C models of varying complexity were tested, and the most accurate in terms of soil C dynamics description in these tropical soils was associated with the QUEFTS model and with nutrient partial balance to analyze the effect of each agricultural management practice. Results indicated that, although fertilizers N, P and K were continuously applied at a recommended rate by the research (RR) or at this rate increased in 50% (1.5RR), initial cotton and cereals yields of 1.5 to 2 t ha˗1 and 2 to 3 t ha˗1, respectively, decre…
A priori parameterisation of the CERES soil-crop models and tests against several European data sets
2002
Mechanistic soil-crop models have become indispensable tools to investigate the effect of management practices on the productivity or environmental impacts of arable crops. Ideally these models may claim to be universally applicable because they simulate the major processes governing the fate of inputs such as fertiliser nitrogen or pesticides. However, because they deal with complex systems and uncertain phenomena, site-specific calibration is usually a prerequisite to ensure their predictions are realistic. This statement implies that some experimental knowledge on the system to be simulated should be available prior to any modelling attempt, and raises a tremendous limitation to practica…
[div]Long-term dynamics of the atrazine mineralization potential in surface and subsurface soil in an agricultural field as a response to atrazine ap…
2012
Abstract The dynamics of the atrazine mineralization potential in agricultural soil was studied in two soil layers (topsoil and at 35–45 cm depth) in a 3 years field trial to examine the long term response of atrazine mineralizing soil populations to atrazine application and intermittent periods without atrazine and the effect of manure treatment on those processes. In topsoil samples, 14 C-atrazine mineralization lag times decreased after atrazine application and increased with increasing time after atrazine application, suggesting that atrazine application resulted into the proliferation of atrazine mineralizing microbial populations which decayed when atrazine application stopped. Decay …
Assessment of Adult Mouse Brain Neuroanatomical Phenotypes Using Quantitative and Precision Histology
2022
Modelling human neurodevelopmental disorders is important in biomedical research since the brain cannot be easily accessed in humans. In this chapter, we describe a series of standardized procedures for the reliable analysis of neuroanatomical phenotypes (NAPs) of the adult mouse brain using quantitative 2D histological practices. Our goal is to provide the reader an experimental pipeline, ranging from experimental work through to data analysis, which can be performed in any academic research setting with or without access to a histology platform. Depending on the type of sections studied, parasagittal or coronal, the assessment of brain neuroanatomy is performed at stereotaxic sections, at…
Ex ante evaluation of gene flow in oilseed rape with cropping sytem models
2009
International audience