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Neutral mesospheric densities at a low latitude have been derived during April 2011 to December 2014 using data from the Kunming meteor radar in China (25.6°N, 103.8°E). The daily mean density at 90 km was estimated using the ambipolar diffusion coefficients from the meteor radar and temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The seasonal variations of the meteor radar‐derived density are consistent with the density from the Mass Spectrometer and Incoherent Scatter (MSIS) model, show a dominant annual variation, with a maximum during winter, and a minimum during summer. A simple linear model was used to separate the effects of atmospheric density and the meteor velocity on the meteor radar peak detection height. We find that a 1 km/s difference in the vertical meteor velocity yields a change of approximately 0.42 km in peak height. The strong correlation between the meteor radar density and the velocity‐corrected peak height indicates that the meteor radar density estimates accurately reflect changes in neutral atmospheric density and that meteor peak detection heights, when adjusted for meteoroid velocity, can serve as a convenient tool for measuring density variations around the mesopause. A comparison of the ambipolar diffusion coefficient and peak height observed simultaneously by two co‐located meteor radars indicates that the relative errors of the daily mean ambipolar diffusion coefficient and peak height should be less than 5% and 6%, respectively, and that the absolute error of the peak height is less than 0.2 km. Neutral mesospheric density in the upper mesosphere was derived at low latitudes using the Kunming meteor radarThe meteoroid velocity‐adjusted peak detection height of the Kunming meteor radar is strongly correlated with a constant density levelThe relative errors of the daily mean ambipolar diffusion coefficient and peak height are less than 5% and 6%, respectively

We report the first observations of a high‐ and middle‐latitude neutral mesospheric density response to geomagnetic storms. Interhemisphere mesospheric densities are estimated using data from meteor radars at Davis Station (68.6°S, 77.9°E), Svalbard (78.3°N, 16°E) and Tromsø (69.6°N, 19.2°E), which are located under the auroral zone; the Mohe (53.5°N, 122.3°E), and Beijing (40.3°N, 116.2°E) meteor radars, located in northern midlatitudes, and the Microwave Limb Sounder (MLS) on the Aura satellite. Both case studies and a superposed epoch analysis indicate that geomagnetic storms can significantly influence mesospheric density, causing a greater than ~10% decrease in the auroral zones and a ~5% decrease at higher midlatitudes. With such large changes, it is reasonable to suspect that geomagnetic storms influence the dynamics of the high and middle latitudes mesosphere. First report of high and middle latitude neutral mesospheric density response to geomagnetic stormsStatistical analysis indicates that mesospheric density under the auroral zone has a more than ~10% decrease in response to stormsThe decrease to mesospheric density due to intense geomagnetic storms extends to middle latitudes

We report an analysis of the neutral mesosphere density response to geomagnetic activity from January 2016 to February 2017 over Antarctica. Neutral mesospheric densities from 85 to 95 km are derived using data from the Davis meteor radar (68.5°S, 77.9°E) and the Microwave Limb Sounder on the Aura satellite. Spectral and Morlet wavelet analyses indicate that a prominent oscillation with a periodicity of 13.5 days is observed in the mesospheric density during the declining phase of solar cycle 24 and is associated with variations in solar wind high‐speed streams and recurrent geomagnetic activity. The periodic oscillation in density shows a strong anticorrelation with periodic changes in the auroral electrojet index. These results indicate that a significant decrease in neutral mesospheric density as the geomagnetic activity enhances. The neutral mesospheric density over Antarctica responds to recurrent geomagnetic activityA 13.5 day oscillation is observed in neutral mesospheric density from 85 to 95 km over Antarctica in the declining phase of solar cycle 24The 13.5 day periodic oscillation in dayside density has a high anticorrelation with periodic changes in the auroral electrojet index

We present a first analysis of 9 and 6.75 day periodic oscillations observed in the neutral mesospheric density in 2005 and 2006. Mesospheric densities near 90 km are derived using data from the Davis meteor radar (68.5°S, 77.9°E; magnetic latitude, 74.6°S), Antarctica. Spectral analysis indicates that the pronounced periodicities of 9 and 6.75 days observed in the mesosphere densities are associated with variations in solar wind high‐speed streams and recurrent geomagnetic activity. Neutral mesospheric winds and temperatures, simultaneously measured by the Davis meteor radar, also exhibit 9 and 6.75 day periodicities. A Morlet wavelet analysis shows that the time evolution of the 9 and 6.75 day oscillations in the neutral mesosphere densities and winds are similar to those in the solar wind and in planetary magnetic activity index, Kpin 2005 and 2006. These results demonstrate a direct coupling between Sun's corona (upper atmosphere) and the Earth's mesosphere. Estimation of mesospheric neutral densities from meteor trail decay times observed by the Davis meteor radarThe 9 and 6.75 day oscillations are observed in mesosphere neutral density over Antarctica in 2005 and 2006These periodic oscillations in density are associated with periodic changes in solar wind and recurrent geomagnetic activity

Evidence suggests that, to maintain treatment effects, nasal continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA) needs to be used every night. What remains unknown is the nightly duration of use required to normalize functioning. This study, employing probit analyses and piecewise regression to estimate dose-response functions, estimated likelihoods of return to normal levels of sleepiness and daily functioning relative to nightly duration of CPAP.

The purpose of this study was to evaluate the Self-Efficacy Measure for Sleep Apnea (SEMSA) designed to assess adherence-related cognitions.

Electroencephalograms (EEGs) and DC electrooculograms (EOGs) were recorded during Transcendental Meditation periods for 8 experienced Ss. The records, scored blind showed that all but 2 Ss spent considerable portions of their meditation periods in unambiguous physiological sleep.