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Gustav Delius
Applied Mathematician: Theoretical Ecology, Stochastic Processes, Symmetry
Applied Mathematician: Theoretical Ecology, Stochastic Processes, Symmetry

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I used plotly to make a graph: . Plotly is a really nice tool for creating graphs quickly interactively.

I was never able to understand how a small country like Greece with only 11 million inhabitants could have accumulated a debt of 330 billion Euros (33,000 euros per inhabitant). Hence I downloaded the trade data from the WTO. It shows an average deficit of 40 billion dollars per year over the last 12 years. That is almost 4,000 dollar for every inhabitant every year. In such a situation debts mount quickly.

The graph below is in US Dollar in current prices. It does not show accumulated deficit but new deficit made every year. 

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We had an interesting talk about Cassava disease today. I must admit that I had never heard of Cassava before. It turns out to be a basic food source for 500 million people. It is somewhat similar to sweet potatoes but excellent for subsistence farming because of its drought resistance, its ability to grow in poor soil, and the fact that one can leave the tubers in the ground until one wants to eat them so that there is no danger of spoilage.
The excellent talk by +Christopher Finn McQuaid from Rothamsted Research was about modelling the spread of Cassava brown streak disease. This disease can lead to a 75% reduction in yield. One way for the disease to spread over longer distances is through the trading of the planting material. The plants are propagated from cuttings of parent plants. If the parent was infected, so will the offspring. It is therefore important to get disease-free planting material to farmers. This is the kind of problem where the mathematical models must take into account not only the ecological factors but also the social factors, in this case how farmers obtain and select their planting material from other farmers. The researchers are therefore planning to collaborate with #sociologists to design appropriate surveys to get at the information.
+Lukas Delius : It turns out that one of the countries most affected by the disease is #Uganda. 

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This article discusses the phenomenon that economists are heard much more than sociologists in the media and that sociologists are often not even consulted by the government when their expertise is clearly relevant. The problem is not that newspapers do not discuss sociological topics. There is a lot of discussion of topics like crime, family, gender equality, discrimination, xenophobia, ... The problem is just that sociological experts are not consulted for these topics, whereas economists are always consulted for economic topics. 

Unfortunately this article does not explain well what led to the prominence of the economists over sociologists, so it is not clear what to do to change things. But one problem seems to be that prominent sociologists in the past tended to be politically biased towards the left, i.e., tended to be anti-establishment. This has very much shaped the public's image of sociologists and makes it difficult for sociologists to be consulted as objective scientific experts. There is a lot of mistrust to be overcome, especially in the more conservative sections of society. 

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Next Friday, September 26th, is the European Researchers' Night. 300 cities across Europe are organising events to bring an understanding of current research to the wider public. The range of events and talks that York is putting on for the night is quite impressive, The talk by our own +Roger Colbeck on quantum cryptography is just one of over 30 scientific talks across York that evening.

If you do not live in York, you can use the map at to check out whether your nearest city is organising something similar.

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Once again an example that shows that we should give also social scientists more training in basic mathematical thought.

This book by Thomas Piketty has made quite a splash and spent many weeks near the top of the amazon best sellers list. The book is published by Harvard University Press and the author is professor at the École des hautes études en sciences sociales and professor at the Paris School of Economics. So tonight I decided I should have a look. 

The first chapter contains the following clear statement: "This fundamental inequality, which I will write as r > g (....) will play a crucial role in this book. In a sense, it sums up the overall logic of my conclusions". The text in parenthesis left out in my quote above even gives a definition of r and g. So I thought this was going to be a book I would like. A book that could be summarised with a simple inequality involving two quantities r and g whose definition I can understand.

Here are the definitions I left out above: "...(where r stands for the average annual rate of return on capital, including profits, dividends, interest, rents, and other income from capital, expressed as a percentage of its total value, and g stands for the rate of growth of the economy, that is, the annual increase in income or output)...". From this definition we see that r has dimensions 1/time and g has dimensions 1/time^2 (the annual increase in annual income). 

Do you see the problem? Should the inequality r >  g be expected to be meaningful even though r and g have different dimensions? No. A natural scientist will spot this problem immediately. I am dreaming of a future where the same will be true of social scientists.

I now want to decide whether I should continue reading the book. Perhaps Professor Piketty only made a mistake when trying to condense his theory into a simple inequality. Maybe a more meaningful theory will be developed later in the book. If you have read beyond the first chapter, can you advise me whether it is worthwhile to read on?

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The article describes the problem well, but does not talk about solutions. But raising awareness of the problem is a good first step. 

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Github has become even better for researchers, with free private repositories and DOIs for your code.

If your research involves any computation, I hope you are already using Github to host your research code so that others can reproduce your research and build on it. Github is also a particularly useful place to keep your code while you are working on it together with your collaborators.

Up to now there was always the small problem that the free Github accounts only allowed public repositories, where anyone could watch you while you were developing your code. This is not always desirable. With the new research accounts you get 5 free private repositories.

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We are hiring again. I am looking forward to interacting with two new colleagues in Mathematical Biology soon. In addition, we have also advertised a statistics lectureship.

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