関: G

WordNet

the 7th letter of the Roman alphabet (同)g
excessive largeness of stature (同)giantism
a booking for musicians; "they played a gig in New Jersey"
a cluster of hooks (without barbs) that is drawn through a school of fish to hook their bodies; used when fish are not biting
long and light rowing boat; especially for racing
small two-wheeled horse-drawn carriage; with two seats and no hood
tender that is a light ships boat; often for personal use of captain

PrepTutorEJDIC

1頭引きの二輪馬車 / (船長用に船に載せてある)快速ボート / 《俗》演奏家の一定期間の仕事
(軍隊・学校で)小過失,処罰,罰点
(短期契約の)ジャズ演奏の仕事
(魚を突き刺す)やす・〈魚･カエルなどを〉やすでとる・やすで魚[カエルなど]をとる

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/09/19 13:25:49」(JST)

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Giga (/ˈdʒɪɡə/ or /ˈɡɪɡə/) is a unit prefix in the metric system denoting a factor of a (short-form) billion (10⁹ or 1000000000). It has the symbol G.

Giga is derived from the Greek word γίγας, meaning "giant". The Oxford English Dictionary reports the earliest written use of giga in this sense to be in the Reports of the IUPAC 14th Conference in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga 10⁹×".

When referring to information units in computing, such as gigabyte, giga may sometimes mean 1073741824 (2³⁰), although such use is inconsistent, contrary to standards and has been discouraged by the standards organizations.^[1]^[2] The inconsistency is that gigabit is never (or very rarely) used with the binary interpretation of the prefix, while gigabyte is sometimes used this way. The binary prefix gibi has been adopted for 2³⁰, while reserving giga exclusively for the metric definition.

Pronunciation

In English, the initial g of giga can be pronounced /ɡ/ (a hard g as in giggle), or (/ˈdʒɪɡə/ (a soft g as in giant, like a j sound, which shares its Greek root).^[3]

This latter pronunciation was formalized within the United States in the 1960s and 1980s with the issue by the US National Bureau of Standards of pronunciation guides for the metric prefixes.^[4] A prominent example is found in the pronunciation of gigawatts in the 1985 movie Back to the Future.

According to the American writer Kevin Self, a German committee member of the International Electrotechnical Commission proposed giga as a prefix for 10⁹ in the 1920s, drawing on a verse by the humorous poet Christian Morgenstern that appeared in the third (1908) edition of Galgenlieder (Gallows Songs). This suggests that a hard German [ɡ] was originally intended as the pronunciation. Self was unable to ascertain at what point the alternative pronunciation came into occasional use, but claimed that as of 1995 it had died out.^[5]

In 1998, a poll by the phonetician John C. Wells found that 84% of Britons preferred the pronunciation of gigabyte starting with /ɡɪ/ (as in gig), 9% with /dʒɪ/ (as in jig), 6% with /ɡaɪ/ (guy), and 1% with /dʒaɪ/ (as in giant).^[6]

Common usage

gigabyte—for instance, for hard disk capacity, 120 GB = 120000000000bytes; for file sizes 1 GB is often 1073741824 or 2³⁰ bytes, more properly termed a gibibyte (GiB) to eliminate ambiguity. The difference is rooted in base 10 and base 2 enumeration, and is also the reason why hard drives advertised as a certain capacity have less than that capacity when installed (as hard drives are advertised in gigabytes or terabytes (base 10) whereas computers format data in gibibytes or tebibytes (base 2, powers of 2). See Hard disk units of storage capacity.
gigahertz—clock rate of a CPU, for instance, 3 GHz = 3000000000Hz
gigabit—bandwidth of a network link, for instance, 1 Gbit/s = 1000000000bit/s.
gigayear or gigaannum—one billion (10⁹) years, sometimes abbreviated Gyr, but the preferred usage is Ga.

Metric prefixes

Prefix	Symbol	1000^m	10ⁿ	Decimal	English word		Since^{[n 1]}
Prefix	Symbol	1000^m	10ⁿ	Decimal	short scale	long scale	Since^{[n 1]}
yotta	Y	1000⁸	10²⁴	1000000000000000000000000	septillion	quadrillion	1991
zetta	Z	1000⁷	10²¹	1000000000000000000000	sextillion	thousand trillion	1991
exa	E	1000⁶	10¹⁸	1000000000000000000	quintillion	trillion	1975
peta	P	1000⁵	10¹⁵	1000000000000000	quadrillion	thousand billion	1975
tera	T	1000⁴	10¹²	1000000000000	trillion	billion	1960
giga	G	1000³	10⁹	1000000000	billion	thousand million	1960
mega	M	1000²	10⁶	1000000	million		1960
kilo	k	1000¹	10³	1000	thousand		1795
hecto	h	1000^2/3	10²	100	hundred		1795
deca	da	1000^1/3	10¹	10	ten		1795
		1000⁰	10⁰	1	one		–
deci	d	1000^−1/3	10⁻¹	0.1	tenth		1795
centi	c	1000^−2/3	10⁻²	0.01	hundredth		1795
milli	m	1000⁻¹	10⁻³	0.001	thousandth		1795
micro	µ	1000⁻²	10⁻⁶	0.000001	millionth		1960
nano	n	1000⁻³	10⁻⁹	0.000000001	billionth	thousand millionth	1960
pico	p	1000⁻⁴	10⁻¹²	0.000000000001	trillionth	billionth	1960
femto	f	1000⁻⁵	10⁻¹⁵	0.000000000000001	quadrillionth	thousand billionth	1964
atto	a	1000⁻⁶	10⁻¹⁸	0.000000000000000001	quintillionth	trillionth	1964
zepto	z	1000⁻⁷	10⁻²¹	0.000000000000000000001	sextillionth	thousand trillionth	1991
yocto	y	1000⁻⁸	10⁻²⁴	0.000000000000000000000001	septillionth	quadrillionth	1991
^ The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.

References

^ "§3.1 SI prefixes" (PDF). The International System of Units (SI) (in French/English) (8th edition ed.). Paris: STEDI Media. 2006. p. 127. ISBN 92-822-2213-6. Retrieved 2007-02-25. "[Side note:] These SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits). The IEC has adopted prefixes for binary powers in the international standard IEC 60027-2: 2005, third edition, Letter symbols to be used in electrical technology — Part 2: Telecommunications and electronics. The names and symbols for the prefixes corresponding to 2¹⁰, 2²⁰, 2³⁰, 2⁴⁰, 2⁵⁰, and 2⁶⁰ are, respectively: kibi, Ki; mebi, Mi; gibi, Gi; tebi, Ti; pebi, Pi; and exbi, Ei. Thus, for example, one kibibyte would be written: 1 KiB = 2¹⁰ B = 1024 B, where B denotes a byte. Although these prefixes are not part of the SI, they should be used in the field of information technology to avoid the incorrect usage of the SI prefixes."
^ NIST Guide for the Use of the International System of Units (Appendix D. ref 5)
^ A Practical Guide to the International System of Units, U.S. Metric Association, Feb 2008
^ NBS Special Publication 304 & 304A, revised August 1981, "A Brief History of Measurement Systems"
^ Kevin Self, April 1995, "Technically speaking", Spectrum
^ Wells, J.C. (1998). LPD pronunciation preference poll 1998.

External links

Look up giga- in Wiktionary, the free dictionary.

BIPM website

English Journal

Normal Reference Ranges for Echocardiography: rationale, study design, and methodology (NORRE Study).

Lancellotti P, Badano LP, Lang RM, Akhaladze N, Athanassopoulos GD, Barone D, Baroni M, Cardim N, Gomez de Diego JJ, Derumeaux G, Dulgheru R, Edvardsen T, Galderisi M, Gonçalves A, Habib G, Hagendorff A, Hristova K, Kou S, Lopez T, Magne J, de la Morena G, Popescu BA, Penicka M, Rasit T, Rodrigo Carbonero JD, Salustri A, Van de Veire N, von Bardeleben RS, Vinereanu D, Voigt JU, Voilliot D, Zamorano JL, Donal E, Maurer G.SourceUniversity of Liège Hospital, GIGA Cardiovascular Science, Heart Valve Clinic, Liege, Belgium.
European heart journal cardiovascular Imaging.Eur Heart J Cardiovasc Imaging.2013 Apr;14(4):303-8. doi: 10.1093/ehjci/jet008. Epub 2013 Jan 31.
BACKGROUND: Availability of normative reference values for cardiac chamber dimensions, volumes, mass, and function is a prerequisite for the accurate application of echocardiography for both clinical and research purposes. However, due to the lack of consistency in current echocardiographic 'referen
PMID 23376837

Neurochemical control of rapid stress-induced changes in brain aromatase activity.

Dickens MJ, Cornil CA, Balthazart J.SourceGIGA Neurosciences, University of Liege, Liège, Belgium.
Journal of neuroendocrinology.J Neuroendocrinol.2013 Apr;25(4):329-39. doi: 10.1111/jne.12012.
In the male brain, the medial preoptic nucleus (POM) is known to be a critical relay for the activation of sexual behaviour, with the aromatisation of testosterone into 17β-oestradiol (E2 ) playing a key role. Acute stress has been shown to differentially modulate the aromatase enzyme in this and o
PMID 23253172

Outcome in Aortic Stenosis: When the Flow Makes the Difference.

Lancellotti P, Dulgheru R.SourceUniversity of Liege Hospital, GIGA Cardiovascular Sciences, Heart Valve Clinic, Department of Cardiology, CHU Sart Tilman, Lieja, Bélgica. Electronic address: plancellotti@chu.ulg.ac.be.
Revista espanola de cardiologia.Rev Esp Cardiol.2013 Apr;66(4):248-250. doi: 10.1016/j.recesp.2012.11.008. Epub 2013 Feb 8.
PMID 23395421