text in graph with expression

Hi all,
 
I'm using 'expression' in the axes labels in graphs to get the greek letters
(ylab), as follows:
 
plot(
 layer_1$U0
 ,layer_1$dP/(H1.Theo)
 #,ylim=c(0,100)
 ,xlim=c(0,1.1)
 #,main="Pressure Drop",
 ,xlab=expression(U[0]~(Nm/s))
 ,ylab=expression(Delta~P~(Pa/m))
 ,col=2
 ,pch=16
 ,cex=1.5)
 
I just need to know how to avoid the use of a space (~) between the greek
letter (Delta) and the rest of the text.

 

Regards/Cordialement

-------------
Benoit Boulinguiez
Ph.D student
Ecole de Chimie de Rennes (ENSCR) Bureau 1.20 
Equipe CIP UMR CNRS 6226 "Sciences Chimiques de Rennes"
Avenue du G?n?ral Leclerc 
CS 50837 
35708 Rennes CEDEX 7 
Tel 33 (0)2 23 23 80 83
Fax 33 (0)2 23 23 81 20
 <http://www.ensc-rennes.fr/> http://www.ensc-rennes.fr/ 

 

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