University of Helsinki
I am evaluating specifications of array detector spectroradiometers.
In the literature one can see them used sometimes for measuring UV-B in sunlight or in UV-B supplementation studies with plants. These single monochromator instruments are not good enough for this. They can overestimate erythemal doses by 100% or more in some cases. So, be careful when reading papers! The most popular brand is Ocean Optics. They are good for visible light measurements. However, with special measuring and calibration procedures they could be used to measure UV-B. I have not seen these special calibrations applied in research with plants, only in the recent methodological literature. I became aware of these from a reference sent to me by Prof. L.O. Bjorn, and investigating this possibilities is also part of the work of one of the technical work groups of the COST action UV4growth. One of the experts on this type of calibration is here in Helsinki, at STUK. I will contact him.
A blog about R
This one in Finnish: http://www.r-ohjelmointi.org/ Full of very interesting stuff on R. Recommended.
Some new R stuff
Because I have some plans for an R course in Moodle, and also because I need to do some plots, I looked around in the web to see if there was something new. I found quite a lot, at least new to me. One is the package ggplot2 that may be easier to use than lattice and produces graphs with a different look.
The author is Had Wickman.
An example:
# load package
library(ggplot2)
# generate some artificial data
x=1:100
y2=x^2/100+rnorm(100)*5
# create a plot
qplot(x,y2,geom=c("smooth","point"))
Here are some links:
ggplot2 the home page for the package with links to videos, slides, etc. The package itself is in CRAN.
The author‘s PhD thesis
Some slides.
He has also written a book on ggplot2.
He has written other interesting packages but I’ll write about them later.
Mixed effects models and extensions in ecology with R
I recently bought this book (a Christmas self-present), by Zuur et al., 2009, and am starting to go through it. If anyone is interested it is available in my office, to augment SenPEP’s already impressive R bibliography!
There is an associated website:
Mixed effects models and extensions in ecology with R
Rob Hyndman’s research tips
Rob Hyndman’s blog has lots of interesting material aimed at graduate students in statistics, also very useful for us, plant ecologists.
http://robjhyndman.com/researchtips/
From reading Rob’s blog came the idea to start this blog for our own group.