The flexibility and relative affordability of phones allows for easy distribution and use, providing distance learning across geographical barriers.

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"In north Wales, there has been relative isolation because people moved less because of geographical barriers, " Prof Donnelly said.

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Telephone counselling also breaks down geographical barriers, offering people help wherever they live in the UK. Further, it offers a greater sense of anonymity.

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AirFlash, a Silicon Valley firm, has developed algorithms that find the closest hotel or cinema to a user's cellphone, taking into account geographical barriers such as rivers and, in the future, traffic conditions.

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"Of all the amazing things animals can do, the ability of certain species to migrate significant distances across formidable geographical barriers is one of the most remarkable, " write the authors of the recent study.

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There are all sorts of things which can act as such barriers to entry: patents, copyrights, trademarks, geographical location, first mover advantage.

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