Charged multiplicities in Z decays into u, d and s quarks                      
  
About 4.4 million hadronic Z0 decays in the OPAL detector at                   
LEP1 are used to                                                               
determine the mean charged particle multiplicities for the three light         
quark                                                                          
flavours and to probe the flavour independence of the strong                   
interaction.                                                                   
Rates of charged particles are measured as: 17.77 +- 0.52 (+0.86,-1.20)        
in                                                                             
uubar events, 21.44 +- 0.69 (+1.46,-1.17) in ddbar events and                  
20.02 +- 0.14 (+0.39,-0.37) in ssbar events (systematic errors are in          
parentheses). With a prediction of the next-to-leading-log approximation       
of QCD these numbers can be translated into                                    
flavour dependent values of alpha_s which are consistent with the              
expectation of flavour independence of the strong interaction.                 
  
 Parallel session :3                   
 Plenary  session :11