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Abstract Studying language evolution brings a crucial perspective to bear on questions of human prehistory. As the most linguistically diverse region on earth, East and Southeast Asia have witnessed extensive sociocultural and ethnic contacts among different language communities. Especially, the Kra-Dai language family exhibits tremendous socio-cultural importance in these regions. Due to limited historical accounts, however, there are several controversies on their linguistic relatedness, ambiguities regarding the divergence time, and uncertainties on the dispersal patterns. To address these issues, here we apply Bayesian phylogenetic methods to analyze the largest lexical dataset containing 646 cognate sets compiled for 100 Kra-Dai languages. Our dated phylogenetic tree showed their initial divergence occurring approximately 4000 years BP. Phylogeographic results supported the early Kra-Dai language dispersal from the Guangxi-Guangdong area of South China towards Mainland Southeast Asia. Coupled with genetic, archaeological, paleoecologic, and paleoclimatic data, we demonstrated that the Kra-Dai language diversification could have coincided with their demic diffusion and agricultural spread shaped by the global climate change in the late Holocene. The interdisciplinary alignments shed light on reconstructing the prehistory of Kra-Dai languages and provide an indispensable piece of the puzzle for further studying prehistoric human activities in East and Southeast Asia.

This is the first time that the landscape footpath is realized on the suspension monorail system. To study the comfort of pedestrians on the landscape footpath when the vehicle passes, the dynamic responses of the track beam and the landscape footpath at different speeds were analyzed using the established vehicle-bridge dynamic analysis model. To evaluate the comfort of pedestrians on the landscape footpath, two indexes, Root Mean Square (RMS) value of acceleration (ISO 10137) and peak value of acceleration (EN 03), were adopted. Results show that the displacement and acceleration responses of landscape footpath and track beam are obviously different. Vertical displacement of the track beam is much larger than that of the landscape footpath due to the eccentric load of vehicles. Due to the displacement and rotation of the structural components which support the landscape footpath, the lateral response transferred to the landscape footpath would be slightly weakened. Maximum RMS values of the lateral and vertical acceleration of landscape footpath are 0.162 m/s2 and 0.169 m/s2, respectively, which meet the requirements of ISO 10137. Peak lateral acceleration is 0.546 m/s2, which reaches CL3 standard, and the peak vertical acceleration is 0.548 m/s2, which reaches CL2 standard. Lateral comfort is slightly worse than vertical comfort.