LarsOlof Björn : UV4Plants Association’s first honorary member

Editorial-board-reviewed article. Published on-line on 2017-03-04.The year 2016 has been a special year for Lars Olof Björn: he turned 80, and formally retired from his professorship at South China Normal University (Guangdong). In addition at the UV4Plants Association's General Meeting in Pécs, Hungary, Lars Olof was named by unanimous vote the first honorary member of the Association. This article is an ecclectic research profile edited by P. J. Aphalo with contributions from Lars Olof himself as well as from his collaborators.Non peer reviewe

Using LEDs : drivers and dimming

In this article I describe how currently available LED drivers and computer interfaces make it easy to build custom light sources. In particular stable light sources with easely repeatable settings useful for photobiological experiments and scientific photography. I also describe alternative approaches to dimming LEDs and the current availability of ultraviolet LEDs and their characteristics.Peer reviewe

Exploring temporal and latitudinal variation in the solar spectrum at ground level with the TUV model

I present examples of the use of Sasha Madronich's Quick TUV Calculator at UCAR together with the R packages in the R for Photobiology suite to produce plots of the solar spectrum and plots and tables of derived quantities and summaries. The article includes as supplements an instructional video on the use of the Quick TUV Calculator to simulate the solar spectrum at different geographic and time coordinates and under different atmospheric conditions including the thickness of the ozone column. The R code and data are supplied so that the code examples can be reproduced and adapted.Non peer reviewe

Extraterrestrial and ground-level solar spectra

This time the question answered relates to the extraterrestrial and ground-level solar spectra. One of ours readers noticed an error in a figure in a book, and asked how to draw a similar figure but avoiding this problem. We provide R code showing how to plot the figures and where to find the spectral data.Non peer reviewe

Neutral density filters: theory vs. reality

Neutral density filters in theory do not affect the shape of the spectrum of radiation that traverses through them. In practice, real neutral density filters are far from being truly neutral and do alter the spectrum of radiation. Not all neutral density filters alter the spectrum to the same extent or in the same way. We here compare the spectral transmittance of six readily available neutral density filters and consider how their effect on the light spectrum can have implications for their use in light sources used in scientific research and on camera lenses used for imaging.Peer reviewe

Practical Hints and Tips [on use of light-emitting diodes in research]

In this first installment I compare the current cost of UV-B LEDs to that five years ago. I describe in detail two type of UV-A flashlights. I describe new types of LEDs emitting light with a "sun-like" spectrum. For the last two items original spectral data from my tests is presented.Non peer reviewe

Exploring Ultraviolet Photography by David Prutchi

A review of a recently published introductory book on methods for digital ultraviolet photography.Non peer reviewe

Absorbance, absorptance and friends

Most photobiologists sooner or later have to measure light absorption, reflection and/or transmission by objects such as plant leaves, optical filters or solutes in a liquid medium. The physical quantities we measure may vary: absorbance, optical density, absorptance, transmittance and reflectance. In addition to these extensive properties of objects we use intensive properties such as the molar extinction coefficient and refractive index. This article disusses the defintions of these quantities and exemplifies some of their uses in research in the field plant photobiology including the study and application of UV radiation. It also touches on some less frequently discussed alspects such as the effect of the angle of incidence on the reflectance at the surface of windows and optical filters.Peer reviewe

OpenIntro Statistics, 3ed by David M. Diez, Christopher D. Barr and Mine Çetinkaya-Rundel

Editorial-board-reviewed article. Published on-line on 2017-02-01.A review of an excellent Open Source Statistics text book.Non peer reviewe