Although the sun is really far away from us, some solar activities could still influence the performance and reliability of space-borne and ground-based technological systems on Earth. Those ...time-varying conditions in space caused by the sun are also called solar storm or space weather. It is known that aviation activities can be affected during solar storms, but the exact effects of space weather on aviation are still unclear. Especially how the flight delays, the top topic concerned by most people, will be affected by space weather has never been thoroughly researched. By analyzing huge amount of flight data (~ 4 × 10
records), for the first time, we quantitatively investigate the flight delays during space weather events. It is found that compared to the quiet periods, the average arrival delay time and 30-min delay rate during space weather events are significantly increased by 81.34% and 21.45% respectively. The evident negative correlation between the yearly flight regularity rate and the yearly mean total sunspot number during 22 years also confirms such correlation. Further studies show that the flight delay time and delay rate will monotonically increase with the geomagnetic field fluctuations and ionospheric disturbances. These results indicate that the interferences in communication and navigation during space weather events may be the most probable reason accounting for the increased flight delays. The above analyses expand the traditional field of space weather research and could also provide us with brand new views for improving the flight delay predications.
Solar flares are one of the severest solar activities that have important effects on near-Earth space. Previous studies have shown that flight arrival delays increase as a result of solar flares, but ...the intrinsic mechanism behind this relationship is still unknown. In this study, we conducted a comprehensive analysis of flight departure delays during 57 solar X-ray events by using a huge amount of flight data (~ 5 × 10
records) gathered over a 5-year period. It is found that the average flight departure delay time during solar X-ray events increased by 20.68% (7.67 min) compared to quiet periods. Our analysis also revealed apparent time and latitude dependencies, with flight delays being more serious on the dayside than on the nightside and longer (shorter) delays tending to occur in lower (higher) latitude airports during solar X-ray events. Furthermore, our results suggest that the intensity of solar flares (soft X-ray flux) and the Solar Zenith Angle directly modulate flight departure delay time and delay rate. These results indicate that communication interferences caused by solar flares directly affect flight departure delays. This work expands our conventional understanding of the impacts of solar flares on human society and provides new insights for preventing or coping with flight delays.
Highlights ► Literature review and pooled data analysis on infant pertussis infection sources. ► Parents were an important source of pertussis infection in very young infants. ► Grandparents were ...seldom implicated in infant pertussis infection. ► Siblings play a role as pertussis a source, but data is heterogeneous. ► Parents should be the focus of post-partum pertussis immunisation.
Abstract
The interaction between the solar wind and the magnetosphere is one of the most important research subjects in the fields of astrophysics and space physics. For more than half a century, ...based on the pressure balance assumption between the solar wind and the magnetosphere and considering other important factors, such as the interplanetary magnetic field and magnetic reconnection process, the dynamic processes at the magnetopause have been extensively analyzed. However, the responses of magnetopause to the solar wind dynamic pressure variations are still complicated to understand. Here, we show that the interaction between the solar wind and the magnetosphere can be regarded as a quasi-elastodynamic process. The driving frequency of the solar wind is determined as a crucial reason for the phase difference between solar wind dynamic pressure variations and magnetopause standoff distance. The low-pass filter effect and oscillation properties of the magnetopause can also be well explained by the forced damped vibrations. Moreover, the quasi-elastodynamic processes predict deformations at the magnetopause, which resemble the magnetopause surface wave. Finally, a three-dimensional time-dependent magnetopause model is constructed and verified by observation. Based on 12,242 magnetopause crossing events, it is found that the new model reveals ∼9.7% better prediction accuracy than the widely used time-independent model. These results can also shed light on our understanding of the solar-wind–magnetopause interaction for other planets.
Renal replacement therapy is rapidly expanding in China, and two-times weekly dialysis is common, but detailed data on practice patterns are currently limited. Using cross-sectional data from the ...China Dialysis Outcomes and Practice Patterns Study (DOPPS), we describe the hemodialysis practice in China compared with other DOPPS countries, examining demographic, social and clinical characteristics of patients on two-times weekly dialysis.
The DOPPS protocol was implemented in 2011 among a cross-section of 1379 patients in 45 facilities in Beijing, Guangzhou and Shanghai. Data from China were compared with a cross section of 11 054 patients from the core DOPPS countries (collected 2009-11). Among China DOPPS patients, logistic and linear regression were used to describe the association of dialysis frequency with patient and treatment characteristics and quality of life.
A total of 26% of the patients in China were dialyzing two times weekly, compared with < 5% in other DOPPS regions. Standardized Kt/V was lowest in China (2.01) compared with other regions (2.12-2.27). Female sex, shorter dialysis vintage, lower socioeconomic status, less health insurance coverage, and lack of diabetes and hypertension were associated with dialyzing two times weekly (versus three times weekly). Patients dialyzing two times per week had longer treatment times and lower standardized Kt/V, but similar quality of life scores.
Two-times weekly dialysis is common in China, particularly among patients, who started dialysis more recently, have a lower comorbidity burden and have financial constraints. Quality of life scores do not differ between the two-times and three-times weekly groups. The effect on clinical outcomes merits further study.
An extended
Ulysses
interplanetary coronal mass ejections (ICMEs) list is used to statistically study the occurrence rate of ICMEs, the interaction of ICMEs with solar wind, and the magnetic field ...properties in ICMEs. About 43% of the ICMEs are identified as magnetic clouds (MCs). It is found that the occurrence rate of ICMEs approximately follows the solar activity level, except for the second solar orbit; the rate is higher in the southern heliolatitude than in the northern heliolatitude; and it roughly decreases with the increase of ICME speeds. Our results show that the speed difference between the ICME and the solar wind in front of it shows a slight decrease with increasing heliocentric distance for ICMEs preceded by a shock, whereas no such dependence is found for the ICMEs without shock association. It is also found that approximately 23% of the ICMEs are associated with radial field events, in which the interplanetary magnetic field with near-radial direction lasts for many hours, in the
Ulysses
detected range, and these associated events are not necessarily confined to fast ICMEs or the trailing portions of ICMEs. Nearly all these associated events occur during the period of declining solar wind speed and most of them occur at low heliolatitudes.
ABSTRACT Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be ...achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.
The magnetic cloud boundary layer (BL) is a dynamic region formed by the interaction of the magnetic cloud (MC) and the ambient solar wind. In the present study, we comparatively investigate the ...proton and electron mean flux variations in the BL, in the interplanetary reconnection exhaust (RE), and across the MC-driven shock by using the Wind data from 1995 to 2006. In general, the proton flux has higher increments at lower energy bands compared with the ambient solar wind. Inside the BL, the core electron flux increases quasi-isotropically and the increments decrease monotonously with energy from ~30% (at 18 eV) to ~10% (at 70 eV); the suprathermal electron flux usually increases in either parallel or antiparallel direction; the correlation coefficient of electron flux variations in parallel and antiparallel directions changes sharply from ~0.8 below 70 eV to ~0 above 70 eV. Similar results are also found for RE. However, different phenomena are found across the shock where the electron flux variations first increase and then decrease with a peak increment (>200%) near 100 eV. The correlation coefficient of electron flux variations in parallel and antiparallel directions is always around 0.8. The similar behavior of flux variations in BL and RE suggests that reconnection may commonly occur in BL. Our work also implies that the strong energy dependence and direction selectivity of electron flux variations, which were previously thought to have not enough relevance to magnetic reconnection, could be considered as an important signature of solar wind reconnection in the statistical point of view.
Observations during the deep solar minimum between Solar Cycles 23 and 24 offer an opportunity for characterizing the nature of solar wind dynamic pressure pulses (DPPs) under extreme solar activity. ...In this study, we identify 226 DPPs from July 2008 to June 2009 using an automatic detection algorithm based on high-resolution plasma data from the
Wind
spacecraft to investigate the features of DPPs during the deep solar minimum. For comparison, the similarities and differences of the statistical characteristics of the DPPs during the deep solar minimum and during the previous solar minimum are also examined. It is found that the number and the occurrence rate of DPPs during the deep solar minimum are only about one-third of those during the previous minimum, which may be attributed to lower solar wind dynamic pressure and weaker dynamic pressure fluctuations. From a statistical perspective, however, no obvious difference is apparent between the other basic DPP properties in the two solar minima, such as the absolute and relative amplitude of the dynamic pressure changes and the durations of the transition regions of DPPs. Other basic properties of the DPPs during the deep solar minimum are as follows: 1) the distribution of the absolute value of the dynamic pressure amplitude change peaks at 1.0 – 1.5 nPa, 2) the most probable relative pressure changes are 0.2 – 0.8, 3) DPP durations are broad-peaked between 150 s and 210 s with a mean of about 171 s, 4) 76.7 % of the DPPs can be considered as pressure balance structures, 5) dynamic pressure changes across DPPs are dominated by density changes, 6) specially, during the deep solar minimum, a considerable portion of DPPs, 86.7 %, are associated with large-scale solar wind transients such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs).
PDF
