To appease the isotope geochemist in me, from the USGS
Isotope Terminology
In everyday speech, isotopes are still described with the element name given first, as in "oxygen-18" or "O-18" instead of "18- oxygen". And many texts, especially older ones that were typeset without superscripts, show the mass number to the right of the element abbreviation, as in C-13 or C13 for carbon-13. However, both in speech and in media, it is becoming more common to put the mass number before the element name, as is 15N.
The stable isotopic compositions of low-mass (light) elements such as oxygen, hydrogen, carbon, nitrogen, and sulfur are normally reported as "delta" (d) values in parts per thousand (denoted as ‰) enrichments or depletions relative to a standard of known composition. The symbol ‰ is spelled out in several different ways: permil, per mil, per mill, or per mille. The term "per mill" is the ISO term, but is not yet widely used. d values are calculated by:
(in ‰) = (Rsample/Rstandard - 1)1000
where "R" is the ratio of the heavy to light isotope in the sample or standard. For the elements sulfur, carbon, nitrogen, and oxygen, the average terrestrial abundance ratio of the heavy to the light isotope ranges from 1:22 (sulfur) to 1:500 (oxygen); the ratio 2H:1H is 1:6410. A positive d value means that the sample contains more of the heavy isotope than the standard; a negative d value means that the sample contains less of the heavy isotope than the standard. A d15N value of +30‰ means that there are 30 parts-per-thousand or 3% more 15N in the sample relative to the standard.
In ASCII-only media, the term delta is almost always denoted with the small Greek letter d. In media lacking this symbol, it is not- uncommonly replaced informally with the letter "d". The term d is spelled and pronounced delta not del. The word del describes either of two mathematical terms: an operator or a partial derivative.
Many isotopers are very sensitive about misuses of isotope terminology. Harmon Craig's immortal limerick says it all:
There was was a young man from Cornell
Who pronounced every "delta" as "del"
But the spirit of Urey
Returned in a fury
And transferred that fellow to hell
There are several commonly used ways for making comparisons between the d values of two materials. The first three are preferred.
* higher vs. lower values
* heavier vs. lighter (the "heavier" material is the one with the higher value)
* more/less positive vs. more/less negative (eg., -10‰ is more positive than -20‰)
* enriched vs. depleted (remember to state what isotope is in short supply; eg., a material is enriched in 18O or 16O relative to some other material).
Statistics
Place: 16 out of 175 Avg (all users): 6.3867 Avg (commenters): 7.1500 Avg (participants): 6.2206 Avg (non-participants): 6.4468 Views since voting: 2122 Views during voting: 381 Votes: 256 Comments: 24 Favorites: 1 (view)
I still don't understand how this scored so well. Look at all the lost detail in the chest area, and the overall image is horribly oversharpened. The quality of the blurred background is so bad that it makes it look like the animal is cut out and pasted on to the bg.
It looks like you have a little sharpening halo on the right side, and he seems a little cramped in the photo. Some of your whites are just a wee bit blown out, but honestly that's all just fishing for something to improve on. You're still in my top 5 picks, heh.
Cool photo. Looks like something got lost in post-processing as this animal almost looks unreal in some places (interior of nose next to the eye, the outside left fur on the neck, and the white on the chest). Perhaps it's natural that way? The fur on the forelegs looks natural. Hmmm. I like how you've filled the frame with the animal. Good luck in the challenge.
Add photograph to your favorites
Add photographer to your favorites
Photographer found comment helpful.
