Revisiting GNRA and UNCG folds: U-turns versus Z-turns in RNA hairpin loops

Revisiting GNRA and UNCG folds: U-turns versus Z-turns in RNA hairpin loops.

When thinking about RNA three-dimensional structures, coming across GNRA and UNCG tetraloops is perceived as a boon since their folds have been extensively described. Nevertheless, analyzing loop conformations within RNA and RNP structures led us to uncover several instances of GNRA and UNCG loops that do not fold as expected. We noticed that when a GNRA does not assume its "natural" fold, it a...

AI Turns Fifty: Revisiting its Origins

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U-turns on ant pheromone trails

Many ant species use branching networks of pheromone trails for orientation between nest and resources [1–3]. Ants on trails make adaptive U-turns for correcting their course using visual cues [4,5] or trail geometry information [2]. However, the role of seemingly non-corrective U-turns on trails is poorly understood. We found that a minority of ants consistently make frequent and seemingly ina...

Development of a New Jughandle Design for Facilitating High- Volume Left Turns and U-turns

U-turns and road safety - perspective from Karachi.

U-turn is a complex driving manoeuvre entailing 180-degree turn to change the direction of travel towards the opposite direction. A cross-sectional survey based on convenience sampling was conducted at 120 U-turns in Karachi from February to October 2013. Shopkeepers operating in the close vicinity of U-turns were interviewed. Out of the 120 U-turns studied, 87(72.5%) were without median and 33...