The relationship between physical health and fear of death in rural residents: The mediation effect of meaning in life and mental health.

The current research used questionnaire data to examine the direct and indirect paths between physical health and fear of death. For 386 rural residents, physical health, meaning in life, and mental health were negatively related to fear of death. Physical health affected fear of death through three paths: one was the independent mediation of meaning in life, the other was the independent mediation of mental health, and the third was the serial mediation of meaning in life and mental health. To reduce the fear of death and improve the quality of life among rural residents, educational interventions of meaning in life and mental health are imperative.

All-passive multiple-place optical phase noise cancellation.

We report on the realization of delivering coherent optical frequency to multiple places based on passive phase noise cancellation over a bus topology fiber network. This technique mitigates any active servo controller on the main fiber link and at arbitrary access places as opposed to the conventional technique, in which an active phase compensation circuit has to be adopted to stabilize the main fiber link. Although the residual fiber phase noise power spectral density in the proposed technique turns out to be a factor of seven higher than that of in the conventional multiple-access technique when the access place is close to the end of the fiber link, it could largely suppress the phase noise introduced by the servo bumps, improve the response speed and phase recovery time, and minimize hardware overhead in systems with many stations and connections without the need for active servo circuits including phase discriminators and active compensators. The proposed technique could considerably simplify future efforts to make precise optical frequency signals available to many users, as required by some large-scale science experiments.

Passive optical phase noise cancellation.

We report on the realization of an optical phase noise cancellation technique by passively embedding the optical phase noise information into a radio frequency signal and creating a copy of the optical frequency signal, which is pre-corrected by the amount of phase noise introduced by optical phase perturbations. Neither phase discrimination nor an active servo controller is required due to the open-loop design, mitigating some technical problems, such as the limited compensation speed and finite phase/timing jitter, in conventional phase noise cancellation. We experimentally demonstrate that this technique maintains the same delay-limited bandwidth and phase noise suppression capability as in conventional techniques, but significantly shortens the response speed and phase recovery time. Passive decoupling optical phase perturbation represents a powerful technique in the domains of optical frequency standard comparisons and tools for future optical atomic clocks, which are now under investigation for a potential redefinition of the International Time Scale.