Time Series Analysis Of Activity Research Articles

MPS 13-05 LOCOMOTOR ACTIVITY IN CONGENIC SHRSPwch1.0 RATS IS DERIVED FROM THE INCREASE IN SYSTOLIC ARTERIAL PRESSURE BUT NOT THE SYSTOLIC ARTERIAL PRESSURE LEVEL ITSELF

Objective: Congenic rats (SHRSPwch1.0) were produced from stroke-prone SHR/Izumo rats (SHRSP/Izm) and Wistar-Kyoto rat/Izumo rats (WKY/Izm). We previously found that the systolic arterial pressure (SAP) and heart rate (HR) of the SHRSPwch1.0 were lower than those of the SHRSP/Izm. However, the SHRSPwch1.0 exhibited greater locomotor activity (ACT) than the SHRSP/Izm. The purpose of this study was to investigate the ACT characteristics of SHRSPwch1.0 in a time-series analysis. Design and Method: We used ten mature male SHRSPwch1.0 and ten male age-matched SHRSP/Izm as controls. They were kept under a 12-hour light and dark cycle in identical conditions. The rats’ SAP, HR, and ACT were monitored using radio telemetry, and their ACT was analyzed using the maximum entropy method to enable a spectral analysis of ACT. Results: All of the examined ACT values (24-hour, dark period, and light period) were greater in the SHRSPwch1.0 than in the SHRSP/Izm. A time-series analysis of ACT in the SHRSPwch1.0 revealed both circadian (23.379 hours) and ultradian variations (16.197 hours and 12.184 hours). On the other hand, the ACT of the SHRSP/Izm exhibited circadian variations (23.190 hours) and an almost imperceptible ultradian rhythm. The power spectral density of the ACT spectrum was greater in the SHRSPwch1.0 than in the SHRSP/Izm. A stronger correlation was noted between ACT and SAP in the SHRSPwch1.0 than in the SHRSP/Izm. In addition, the ACT response to increases in SAP was stronger in the SHRSPwch1.0 than in the SHRSP/Izm. However, the ACT response to increases in HR did not differ between the SHRSPwch1.0 and SHRSP/Izm. Conclusions: These findings suggest that ACT continues for longer in SHRSPwch1.0 than in SHRSP/Izm. In SHRSPwch1.0, ACT is strongly correlated with the magnitude of increases in SAP, but not the SAP level itself or the size of increases in HR.

Time-series analysis of effusive volcanic activity using the ERS along track scanning radiometer: The 1995 eruption of Fernandina volcano, Galápagos Islands

The ERS-1 Along Track Scanning Radiometer (ATSR) provides frequent shortwave and longwave infrared radiance data of every terrestrial volcanic region, at a spatial resolution of 1 km 2. By adopting a simplified model that assumes that any observed active lava flow is composed of two distinct thermal components, we present techniques that allow subpixel lava flow areas to be estimated from the ATSR spectral radiance data. Such estimates are especially useful in documenting effusive volcanic activity occurring in remote regions, where ground observations may be sparse or completely lacking. We use a time-series ATSR dataset to document the 1995 eruption of Fernandina Volcano, an important but isolated volcanic island in the Galápagos archipelago. We estimate that in 1995 Fernandina produced a 6 km 2 lava flow field with a volume of around 20 million m 3, a similar magnitude to previously studied Fernandina eruptions. This is the first time-series analysis of an active Galápagos lava flow produced using remotely sensed data. Previous Fernandina flows have been investigated many months or years after the activity had ceased. The current and future availability of frequent, low-spatial resolution infra-red radiance data from spaceborne sensors such as the Advanced Along Track Scanning Radiometer (AATSR) and the Moderate Resolution Imaging Spectrometer (MODIS) should ensure that adaptations of these techniques can be used to document future volcanic eruptions occuring in similarly isolated regions.