Investigating the Photostability of Carboxylic Acids Exposed to Mars Surface Ultraviolet Radiation Conditions

Astrobiology ◽  
2009 ◽  
Vol 9 (6) ◽  
pp. 543-549 ◽  
Author(s):  
F. Stalport ◽  
P. Coll ◽  
C. Szopa ◽  
H. Cottin ◽  
F. Raulin
Keyword(s):  
Ultraviolet Radiation ◽  
Carboxylic Acids ◽  
Radiation Conditions

scholarly journals Adaptation to local ultraviolet radiation conditions among neighbouring Daphnia populations

2010 ◽  
Vol 278 (1710) ◽  
pp. 1306-1313 ◽  
Author(s):  
Brooks E. Miner ◽  
Benjamin Kerr
Keyword(s):  
Ultraviolet Radiation ◽  
Environmental Variables ◽  
Population Genetic ◽  
Phenotypic Diversity ◽  
Experimental Population ◽  
Phenotypic Divergence ◽  
Trade Offs ◽  
Adaptive Processes ◽  
Subdivided Populations ◽  
Radiation Conditions

Understanding the historical processes that generated current patterns of phenotypic diversity in nature is particularly challenging in subdivided populations. Populations often exhibit heritable genetic differences that correlate with environmental variables, but the non-independence among neighbouring populations complicates statistical inference of adaptation. To understand the relative influence of adaptive and non-adaptive processes in generating phenotypes requires joint evaluation of genetic and phenotypic divergence in an integrated and statistically appropriate analysis. We investigated phenotypic divergence, population-genetic structure and potential fitness trade-offs in populations of Daphnia melanica inhabiting neighbouring subalpine ponds of widely differing transparency to ultraviolet radiation (UVR). Using a combination of experimental, population-genetic and statistical techniques, we separated the effects of shared population ancestry and environmental variables in predicting phenotypic divergence among populations. We found that native water transparency significantly predicted divergence in phenotypes among populations even after accounting for significant population structure. This result demonstrates that environmental factors such as UVR can at least partially account for phenotypic divergence. However, a lack of evidence for a hypothesized trade-off between UVR tolerance and growth rates in the absence of UVR prevents us from ruling out the possibility that non-adaptive processes are partially responsible for phenotypic differentiation in this system.

scholarly journals The PROCESS Experiment: Amino and Carboxylic Acids Under Mars-Like Surface UV Radiation Conditions in Low-Earth Orbit

Astrobiology ◽  
2012 ◽  
Vol 12 (5) ◽  
pp. 436-444 ◽  
Author(s):  
Audrey Noblet ◽  
Fabien Stalport ◽  
Yuan Yong Guan ◽  
Olivier Poch ◽  
Patrice Coll ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Uv Radiation ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Radiation Conditions

scholarly journals Effect of Nontronite Smectite Clay on the Chemical Evolution of Several Organic Molecules under Simulated Martian Surface Ultraviolet Radiation Conditions

Astrobiology ◽  
2015 ◽  
Vol 15 (3) ◽  
pp. 221-237 ◽  
Author(s):  
Olivier Poch ◽  
Maguy Jaber ◽  
Fabien Stalport ◽  
Sophie Nowak ◽  
Thomas Georgelin ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Chemical Evolution ◽  
Organic Molecules ◽  
Martian Surface ◽  
Smectite Clay ◽  
Radiation Conditions

scholarly journals UVolution, a Photochemistry Experiment in Low Earth Orbit: Investigation of the Photostability of Carboxylic Acids Exposed to Mars Surface UV Radiation Conditions

Astrobiology ◽  
2010 ◽  
Vol 10 (4) ◽  
pp. 449-461 ◽  
Author(s):  
Fabien Stalport ◽  
Yuan Yong Guan ◽  
Patrice Coll ◽  
Cyril Szopa ◽  
Frédérique Macari ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Uv Radiation ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Radiation Conditions

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

803: Interactions Between Ultraviolet Radiation and Polymorphisms in the Vitamin D Receptor Gene Mediate Prostate Cancer Susceptibility

2006 ◽  
Vol 175 (4S) ◽  
pp. 260-260
Author(s):  
Nicholas J. Rukin ◽  
Samuel J. Moon ◽  
Dhaval Bodiwala ◽  
Christopher J. Luscombe ◽  
Mark F. Saxby ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Vitamin D ◽  
Ultraviolet Radiation ◽  
Vitamin D Receptor ◽  
Cancer Susceptibility ◽  
Receptor Gene ◽  
Vitamin D Receptor Gene ◽  
Prostate Cancer Susceptibility
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