Three dimensional (3D) topological Dirac/Weyl semimetals are currently a new frontier and focus topic in condensed matter physics and materials science.

三维拓扑狄拉克/外尔半金属是近期凝聚态物理和材料科学领域的一个新的研究热点，并得到了广泛的关注。

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You start by seeding it with the name of a topic, several article links that you know are on topic, and links to profiles of people that you know focus on that topic.

FORBES: Is This What Tom Cruise Reads on Twitter?

As the convoluted title of this book suggests, Robert Peston struggles to focus on one topic.

ECONOMIST: The financial crisis

Our planners, media and thinking people focus on this topic once every four years, and usually a day before the Olympics -- as if it were a periodic celestial event!

CNN: ASIANOW - TIME Asia | Subcontinental Drift: Lame Games