Extremes of political opinion have been expressed about the Philharmonic's decision to accept this invitation.
And worries have been expressed about the spread of sex tourism.
Concern has been expressed about the reliability of electoral rolls given rapid population shifts and the possibility of deliberate fraud.
In addition, concerns have been expressed about the possibility of fraud during the balloting and the vote count.
Many children are being routinely exposed to such material while surfing on the internet and real fears have been expressed about the permanent psychological damage this could cause.
And, although many concerns have been expressed about the potential for unexpected consequences, the unexpected effects that have been observed so far have been benign.
Rubio said that since the introduction of the bill "legitimate concerns" had been expressed about the impact it could have on access to the internet "and about a potentially unreasonable expansion of the federal government's power to impact the internet".
Additional concerns have been expressed about the big rise in the use of small-group isolation in Europe, in which people are segregated from the general population, although not necessarily from each other.
Having confirmed Steve Round, Chris Woods and Jimmy Lumsden were following him from Everton, concern had been expressed about the lack of United experience in Moyes's backroom team following his appointment as Sir Alex Ferguson's successor.
Within social work, for example, concerns have been expressed about the downgrading of social work posts (by appointing brokers in their place, say) and the resulting loss of professional skills and knowledge.
Some have fared even worse – a young gay American killed himself following an alleged "exorcism", while concerns have been expressed about the effect of homophobic preaching on others who have taken their lives.
