A long period Pc5 pulsation was observed at Phimai in Thailand, shortly after the origin time of the Sumatra earthquake on December 26, 2004. The localized nature and the period of oscillations ...suggest that the long period magnetic pulsation was generated by dynamo action in the lower ionosphere, set up by an atmospheric pressure pulse which propagated vertically as an acoustic wave when the ocean floor suddenly moved vertically. It is speculated that a Pc3 type pulsation observed at Tong Hai in China, 10 degrees north of Phimai in latitude, was the result of magnetic field line resonance with a magneto‐sonic wave generated from the electric and magnetic fields of the dynamo current caused by the Earthquake.
Ørsted is a low‐altitude polar orbiting satellite, which is advantageous for investigating the spatial structure of low‐frequency events like Pi2 pulsations. Using 1‐s vector magnetic field data from ...April 1999 to May 2002 obtained from Ørsted and Kakioka magnetic observatories, we found that the field aligned component (B∥) of Pi2 pulsations at the satellite height is highly correlated with the H component on the ground, but the other two components, i.e., eastward component (BE) and radial component (BR), do not show a clear correlation with the ground observations. The observed results for nightside events provide evidence that nightside Pi2s at low latitude are generated from cavity resonance. Two cases observed by Ørsted when it was located on the dawnside or duskside also show cavity resonance properties. However, when Ørsted was on the dayside, the oscillations observed by the satellite are out of phase with that observed on the ground, suggesting that the dayside Pi2s are more likely related to some dayside ionospheric current systems rather than that caused by a global cavity resonance mode. The amplitude variation recorded by Ørsted shows a peak in the equatorial region, which, for the first time, gives clear observational support for earlier model calculations. We also estimated the screening effect of the ionosphere on MHD waves and suggest that when the cavity resonance mode is valid for generation of Pi2 pulsations at low latitudes, the screening effect is negligible; that is, the compressional waves are seen directly as Pi2 pulsations at the ground.
Recently, a wealth of information has emerged connecting the activation of the NLRP3 (NOD-like receptor family pyrin domain-containing 3) inflammasome to stroke pathogenesis, although the exact ...influence of the NLRP3 inflammasome on stroke is still in the stage of preliminary study and is awaiting further confirmation. In this paper, we will review the structure, assembly and activation of the NLRP3 inflammasome and its expression in the neurovascular units and will speculate on its possible roles in neurovascular injury post-stroke. Evidence on this topic suggests that targeting NLRP3-mediated inflammation at multiple levels may provide a new therapeutic strategy to prevent the deterioration of neurovascular units after stroke. However, many aspects of the biological link between the NLRP3 inflammasome and stroke remain ill-defined or even completely unknown. As fresh insights come to light regarding the NLRP3 inflammasome, the opportunities to develop new therapeutic strategies for stroke patients are expected to improve accordingly.
The dependence of the storm-time amplitude on longitude and latitude was analyzed by statistically investigating great magnetic storms observed at different observatories. First, we compared the ...storm-time ranges observed at Beijing Observatory (BJI) and San Juan Observatory (SJG) to reveal their longitudinal dependence. It was found that the difference between BJI and SJG could be fitted by the 4-order Fourier series approximation, and the storm-time
H
ranges at dawn were less than those at dusk. Second, we carried out a case study of two typical storms, and analyzed the focused local time when peak storm-time
H
ranges occurred. The results confirmed the above conclusion. Third, a statistical study was conducted for all magnetic storms observed at the 120°E magnetic chain in eastern China for 1995–2004 to reveal the latitudinal dependence of storm-time ranges. It was found the relationship depended on the activity of analyzed storms and became complicated for giant storms with
Dst
≤ −300 nT.
A complete statistical study is made for all magnetic storms reported by Beijing observatory during 1979 to 2000. It includes occurrence dependence on type of the storm, intensity of the storm, and ...time (year, season, and month). A comparison between the occurrence and the number of sunspots is also carried out. Further statistical analysis for part of the great magnetic storms shows that there are obvious differences between activity level represented by Beijing observatory and that by Dst. Such differences depend upon local time of Beijing (BLT). Cubic polynomial fitting results show that the activity level is lower at dawn and higher at dusk in Beijing than that represented by Dst, and the difference between dusk and dawn is about 63% of Dst.
One-second resolution geomagnetic data from 5 stations located at low-latitudes (i.e., L = 1.2 ~ 1.6) were used to examine the local time dependence of the dominant frequency of Pi2 pulsations. We ...analyzed 183 Pi2 events simultaneously recorded at the 5 stations and discussed their possible generation mechanisms. The averaged dominant frequency of the H (horizontal) component is higher on the dawn side than that on the dusk side and shows a peak value in the post-midnight at around 03 LT, which confirms the LT dependence previously suggested from single station data (i.e., non-simultaneous observation). However, some of the events have no LT dependence. For the events which show the LT dependence at low-latitudes, we infer that the cavity resonance mode is a plausible generation mechanism, but we do not rule out the possibility of the plasmaspheric surface wave mode which has also been suggested. For the events having a common frequency between the eastern and western stations, we suggest the cavity resonance mode to be the mechanism. The averaged dominant frequency of the D component does not show any clear LT dependence, and only about 20% of Pi2s have identical frequency for both the H and D components, therefore we suggest that the H and D oscillations of Pi2s are generated from different mechanisms. We also found that the frequency of different parts of a Pi2 pulsation, i.e., the dominant frequency for leading part and trailing part of the pulsation, is different, and the frequency of the trailing part is lower than that of the leading part.
Relativistic (E >1.6 MeV) electron flux enhancements during Solar Energetic Particle (SEP) events as observed by the synchronous FY-2 satellite at orbit located at 105°E are investigated. Energetic ...protons during SEP events heavily contaminate relativistic electron flux measurements. The ratio of the contamination in the original measurement of relativistic electron flux was over 30% during most of the SEP event on July 14, 2000. A method has been developed to eliminate the contamination caused by the energetic protons, and a "corrected" relativistic electron flux has been obtained. The "cleaned-up" relativistic electron flux measurement shows that relativistic electron flux enhancement at synchronous orbit is well correlated with SEP events during which the IMF Bz has some southward periods. The enhancement could arise as the transport of relativistic electrons from the upstream solar wind into synchronous orbit via the magnetotail.
The book is the first thorough study of the role of phosphorus chemistry in the origin of life. This book starts with depiction of the phosphorus role in life creation and evolution. Then it outlines ...in vital processes how different phosphorus-containing compounds participate as biomarker in life evolution. Written by renowned scientists, it is suitable for researchers and students in organic phosphorus chemistry and biochemistry.
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