It was already in October that the report on the use of an R markdown template or using nonlinear mixed-effects models (also known as nonlinear hierarchical models) for chemical degradation kinetics was published by the German Environment Agency. The report should be useful to scientists or consultants working on degradation …

In the beginning of the year I have joined Agroscope, the Swiss competence center for research in agriculture, the food economy and the environment. There, I have joined the group evaluating effects and impacts of pesticides which is located in Wädenswil. After working formally on my own in the last …

A week ago I had the opportunity to give a presentation (slides/pdf) on the application of nonlinear mixed-effects models to degradation kinetics at SETAC Europe in Copenhagen. In case you find yourself wondering what these models are and why we are so enthusiastic about them, this presentation gives a …

Update 2023

As I am now employed with 80% of a full-time position at Agroscope, my capacity to do regulatory fate modelling is very limited.

Degradation kinetics

Evaluation of degradation study data:

• OECD 307: aerobic or anaerobic soil
• OECD 308: water/sediment
• OECD 309: surface water
• field dissipation trials
• Various …

I am very happy to be able to announce the publication of the article Taking Kinetic Evaluations of Degradation Data to the Next Level with Nonlinear Mixed-Effects Models. It originated from an investigation of model selection criteria commissioned by the German Federal Environment Agency. During the course of that work …

More than 10 years after the first code of the 'mkin' package was published, I am happy to announce the release of mkin version 1.0!

With the version number I would like to indicate that the approach taken in the package is mature and battle-proven, and further significant developments …

Working on the application of nonlinear mixed-effects models to chemical degradation data, it became desirable to further speed up the solution of at least the most common degradation models used in the mkin package, simple first-order (SFO) decline of the parent compound coupled to SFO decline of a metabolite, or …

Introduction

Ever since I have read the refresher of Tjalling Jager on differential equations and likelihood functions, I have been irritated about the common way to express the likelihood of data following a normal distribution using the density function of the normal distribution. The statement that made me wonder was …

I am happy to announce that the publication on the software comparison of kinetic evaluation software is now available online! As the supporting information containing the numerical results obtained with the test datasets published on the journal website is marked as "Draft", I have prepared a version for publicaton on …

This is a short note about reading tables from common office document formats into R.

xls and xlsx

After problems with large worksheets I have turned to using the readxl package.

require(readxl)
sheet_names <- excel_sheets("my_file.xls")
d <- read_excel("my_file.xls", sheet = 1, range = "A3:C7", col_names = TRUE)

docx

Recently …

Upon finishing some projects, I found the time to update this web server (from Debian wheezy to Debian jessie) and to give the web site a new design.

And after the start of the new year, the translation of the site to German is completed as well.

With great pleasure I am introducing my new company in this little weblog posting. The company is simply called “Johannes Ranke, wissenschaftlicher Berater”. This means I am running a one-man scientific consulting company. Continuing from my activities at the University of Bremen, at Harlan Laboratories and most recently at Eurofins …