Yocto – the lost Marx brother?

My chief assignment as a molecular biologist is to redistribute minuscule volumes of various liquids from one location to another.  As I became increasingly proficient, the SI prefixes milli, micro and nano became very familiar to represent the liquid dilution factors of 10^-3, 10^-6 and 10^-9 respectively.  Very occasionally we plunge to the depths of picomolar (10^-12) and, for exquisitely sensitive assays, femtomolar (10^-15) solutions.

On a slow Friday afternoon in a previous job I got to wondering what the next prefix would be if I ever wanted to dilute my femtomolar solution by another factor of 10^-3.  The answer, shown in the table below, was ‘atto’ (10^-18), and if I was inclined to dilute my attomolar solution yet again, it would become zeptomolar (10^-21). 

Prefix	Abbr	10n	Since	Root	Meaning
yotta	Y	10 +24	1991	Greek	ὀκτώ: meaning eight, (10008)
zetta	Z	10 +21	1991	Latin	septem: seven; (10007).
exa	E	10 +18	1975	Greek	ἑξά: six; (10006)
peta	P	10 +15	1975	Greek	πέντε: five; (10005)
tera	T	10 +12	1960	Greek	τέρας: meaning 'monster'.
giga	G	10 +9	1960	Greek	γίγας: meaning 'giant'
mega	M	10 +6	1960	Greek	μέγας: meaning 'great'
kilo	k	10 +3	1795	Greek	χίλιοι: meaning 'thousand'
hecto	h	10 +2	1795	Greek	ἑκατόν: meaning 'hundred'
deca	da	10 +1	1795	Greek	δέκα: meaning 'ten'
deci	d	10 -1	1795	Latin	decimus: meaning 'tenth'
centi	c	10 -2	1795	Latin	centum: meaning 'hundred'.
milli	m	10 -3	1795	Latin	mille: meaning 'thousand'
micro	μ	10 -6	1960	Greek	μικρός: meaning 'small'
nano	n	10 -9	1960	Greek	νᾶνος: meaning 'dwarf'
pico	p	10 -12	1960	Italian	piccolo: meaning 'small'
femto	f	10 -15	1964	Danish	femten: meaning 'fifteen'
atto	a	10 -18	1964	Danish	atten: meaning eighteen'
zepto	z	10 -21	1991	Latin	septem: meaning 'seven'
yocto	y	10 -24	1991	Greek	οκτώ, meaning 'eight'

At this point I chuckled to myself because I thought that Zepto was one of the Marx brothers, and therefore we should designate the next lower prefixes as grouchomolar (10^-24), chicomolar (10^-27) and harpomolar (10^-30).  As it turns out the 10^-24 prefix was already assigned to yoctomolar – though I don’t recall any Yocto Marx brother. 

It turns out I wasn’t the only one who ever had a slow day in the lab and started wondering about SI prefixes.  In 2010, Austin Sendek, a physics student at UC Davis, wondered about the highest prefix currently assigned to 10⁺²⁴: 'yotta'; where do you go after that?  He proposed that the 10⁺²⁷ prefix should be assigned to ‘hella’ at the uppermost end of the list, ‘hella’ being North Californian slang for "very" or "a lot of".  Examples in daily local use are “Those Dodger fans are hella late to the game (as usual)” or “There's hella chocolate in that cake”.  As far as I can tell he is serious in his quest, with a blog and the obligatory Facebook petition.  At the time of writing the petition has reached 63,681 votes (which is 63.7 kilovotes, or 0.06 megavotes but only 6x10^-23 hellavotes).  So far the only implementation of ‘hella’ appears to be at Google (always the paradigm for early adopter) who have included the ‘hella’ prefix in its calculator: 1 light year is 9.4 x 10^-12 hellameters. 

The official adoption of ‘hella’ as an SI prefix would require ratification by the Bureau international des poids et mesures.  The task of the BIPM is to ensure world-wide uniformity of measurements, and was set up under a diplomatic treaty between fifty-five nations; its members are the national metrology laboratories of the signatory states (thank you Wikipedia!).  In 1960, BIPM adopted the name Système International d'Unités (hence SI units) for the “recommended practical system of units of measurement”, and defined the rules for their prefixes.  The original SI prefixes were originally assigned in 1795 and were based on Greek and Latin – the languages of science in that period; there were subsequent additions in 1960, 1964, 1975 and 1991. 

While SI prefix updates have generally stuck with Greek and Latin based etymology, in 1964 the Danish language made a fleeting appearance – I have yet to discover why.  Le BIPM assigned ‘femto’  to 10^-15 ('femten' is Danish for fifteen) and ‘atto’ to 10^-18 ('atten' is Danish for eighteen).  I wonder how the discussion started: “Hey guys, we’ve already used the Greek and Latin words for small, teensy and itsy bitsy – anyone got any ideas?”  At this point in the proceedings the Danish delegate seized the moment and piped up with ‘femto’ and ‘atto’.  Perhaps he preemptively averted any resistance by bringing a hectoliter of Danish pilsner beer to the lunchtime recess - just a hypothesis. 

The next SI meeting is scheduled in October of 2011 - I will send a DVD of “A Night at the Opera”, a box of cigars and joke spectacles/moustaches for each delegate to lobby for ‘groucho’ as the prefix for 10^-27 – though it's hella unlikely to be ratified either. 


Finally, a bit of SI prefix humor stolen from the BBC (nerd page):

10 cards = one decacards

One trillion pins = one terrapin

1,000 whales = one killer whale

One trillion microphones = one megaphone

10²¹ piccolos = one gigolo

2,000 mockingbirds = two kilomockingbirds

Write what you know...

It's an old adage that when you start to write you should write about what you know.  So, I'll kick off my blog with the not-so-holy trinity of the three things that I know most about (in no particular order):

• Science
• Soccer
• Food

I figured if I could hit all three that would be the best place to start.   Somehow, while I was kicking around ideas during my 'research'  I found an article on a more-than-life-size chocolate statue of David Beckham in Japan.  Bingo! I hit the trifecta. The three metre-high statue was created by confectionery manufacturer, Meiji, as part of an advertising campaign for their new "Almond Choco" sweet in 2002. The word "tasty" came to my mind.  Twice.


In much smaller doses than you would find in any statue, dark chocolate is now considered quite healthful due to its cocoa phenols.  Chocolate contains more antioxidants than red wine or teas, and in particular dark chocolate, is considered one of the major contributors of antioxidants to the American diet after fruits and vegetables.  It's important to keep the dose small, just a couple of pieces, so that the benefits are not outweighed by the increase in calories.  45g of dark chocolate a day  improves HDL cholesterol in diabetes patients, reduces blood pressure, and reduces cardiovascular disease. Delicious chocolate with health benefits - I would feel cheated in the placebo group in these studies.       

To get the most bang for your buck, choose a bar with 80% or greater cocoa content.  My current favorites are: Green and Black Organic Dark (85%), Valrhona Le Noir (85%) and if you're feeling particularly adventurous, try Endangered Species at a mouth puckering 88%.  


So, forget the guilt and enjoy this important component of your diet - just remember to limit your serving size to half of one of Becks's chocolate fingers.  

The postman did not come today

Stupid postman...