RESUMEN
Background: College students' insomnia symptoms is a topic of growing interest and studies have begun to explore the factors that influence college students' insomnia symptoms. This study investigated the relationship between perceived stress and college students' insomnia symptoms, as well as the chain mediating roles of fear of missing out and mobile phone dependence, and the moderating roles of environmental sensitivity. Methods: In this study, 748 college students (M = 20.59, SD = 2.65) as a sample for cross-sectional study. The Perceived Stress Questionnaire, Brief Fear of Missing Out Scale, Self-Rating Questionnaire for Adolescent Problematic Mobile Phone Use, Athens Insomnia Scale and Highly Sensitive Child Scale were used. Results: (1) Perceived stress significantly positively predicts the insomnia symptoms of college students; (2) Fear of missing out and mobile phone dependence play a chain mediating role between perceived stress and the insomnia symptoms of college students; (3) environmental sensitivity moderated the pathways of mobile phone dependence on insomnia symptoms. Conclusion: We revealed the underlying mechanisms between perceived stress and insomnia symptoms. The findings highlight the importance of interventions for fear of missing out and mobile phone dependence, as well as the role of environmental sensitivity in influencing insomnia symptoms.
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Optical beam wander is one of the most important issues for free-space optical (FSO) communication. We theoretically derive a beam wander model for Bessel beams propagating in turbulent atmosphere. The calculated beam wander of high order Bessel beams with different turbulence strengths are consistent with experimental measurements. Both theoretical and experimental results reveal that high order Bessel beams are less influenced by the turbulent atmosphere. We also demonstrate the Bessel beams based orbital angular momentum (OAM) multiplexing/demultiplexing in FSO communication with atmospheric turbulence. Under the same atmospheric turbulence condition, the bit error rates of transmitted signals carried by high order Bessel beams show smaller values and fluctuations, which indicates that the high order Bessel beams have an advantage of mitigating the beam wander in OAM multiplexing FSO communication.
RESUMEN
Space-division multiplexing allows unprecedented scaling of bandwidth density for optical communication. Routing spatial channels among transmission ports is critical for future scalable optical network, however, there is still no characteristic parameter to label the overlapped optical carriers. Here we propose a free-space optical flow routing (OFR) scheme by using optical orbital angular moment (OAM) states to label optical flows and simultaneously steer each flow according to their OAM states. With an OAM multiplexer and a reconfigurable OAM demultiplexer, massive individual optical flows can be routed to the demanded optical ports. In the routing process, the OAM beams act as data carriers at the same time their topological charges act as each carrier's labels. Using this scheme, we experimentally demonstrate switching, multicasting and filtering network functions by simultaneously steer 10 input optical flows on demand to 10 output ports. The demonstration of data-carrying OFR with nonreturn-to-zero signals shows that this process enables synchronous processing of massive spatial channels and flexible optical network.