After researchers saw these preliminary results, they stopped recruiting patients to take part in the study.

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Only schools which permitted their students to take part in the study were considered for the lists.

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Scientists will randomly select 400 patients who have undergone surgery from hospitals across the UK to take part in the study.

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More than 350 members of the public volunteered to take part in the study, which involved training in identifying species and conducting surveys.

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Some nations may take part in one international survey, but not in another, the study said, and a lot of emphasis can be placed on small differences between countries' test scores.

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About 100 volunteers are being sought for the study, half of which will be asked to take part in indoor activities and half outdoor exercise.

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The key point is that there are strict rules about gaining the consent of patients and carers before they take part in a clinical research study - and these rules are taken very seriously indeed.

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While more companies are allowing employees to work when and where they want to, they increasingly are limiting people's ability to take a leave or work part-time, the Families and Work Institute found in its 2012 National Study of Employers.

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