Avoiding gluten has added a layer of challenges, and there are countries that are tough to visit as a celiac, where gluten reigns.
In a preseason interview in Argentina, during his South American exhibition tour, Federer said one of his hopes was that the new wave of men's players would assert itself in 2013, providing a new layer of challenge at the talent-rich top of the men's game.
The results here potentially add a new layer of challenge to the evolution of cooperation, not only for cross-feeding, but potentially to other mutli-species systems.
Second, imperfectly optimizing individuals create an additional layer of challenges for providing job training services through market-based mechanisms, a potentially efficient way to deliver such benefits for standard rational economic actors.
I'm sure the founders would like to take the site to the next level, make it a business and that will bring a whole new layer of challenges – but it looks good so far.
Homelessness adds a layer of difficulty to the initial challenges posed by poverty.
Adjustable resistance adds another layer of challenge, and the shoes weigh four pounds each.
The gameplay was adjusted to allow the player the option to quickly play through the game's story, but head director Toshihiko Kujioka also wanted to add in gameplay elements that would add another layer of challenge.
However, Kujioka also wanted to add in gameplay elements that would add another layer of challenge, such as the introduction of the choreography panel to make adjustments to an idol's dance sequence or the positioning and manipulation of in-game cameras.
Which leaves us with the dilemma of how to update our wardrobes... Instead of abandoning our inner Athena, we've decided to rise to the challenge, remove a layer of woolly jumper, and accent our winter basics with some serious, don't-mess-with-me jewellery.
