[1] Ionospheric scintillation is a rapid change in the phase and/or amplitude of a radio signal as it passes through small-scale plasma density irregularities in the ionosphere. These scintillations not only can reduce the accuracy of GPS/Satellite-Based Augmentation System (SBAS) receiver pseudorange and carrier phase measurements but also can result in a complete loss of lock on a satellite. In a worst case scenario, loss of lock on enough satellites could result in lost positioning service. Scintillation has not had a major effect on midlatitude regions (e.g., the continental United States) since most severe scintillation occurs in a band approximately 20°on either side of the magnetic equator and to a lesser extent in the polar and auroral regions. Most scintillation occurs for a few hours after sunset during the peak years of the solar cycle. Typical delay locked loop/phase locked loop designs of GPS/SBAS receivers enable them to handle moderate amounts of scintillation. Consequently, any attempt to determine the effects of scintillation on GPS/SBAS must consider both predictions of scintillation activity in the ionosphere and the residual effect of this activity after processing by a receiver. This paper estimates the effects of scintillation on the availability of GPS and SBAS for L1 C/A and L2 semicodeless receivers. These effects are described in terms of loss of lock and degradation of accuracy and are related to different times, ionospheric conditions, and positions on the Earth. Sample results are presented using WAAS in the western hemisphere.
Enhancements are under consideration for the Federal Aviation Administration's (FAA) Category I (CAT I) Local Area Augmentation System (LAAS) to meet the more stringent performance requirements of CAT IIIb operations. This paper analyzes the relative improvement predicted for various alternatives designed to enhance LAAS CAT IIIb availability. These enhancements include increasing the number of ranging sources, using less-conservative error models, taking credit for redundant GPS navigation sensors in the aircraft, using a second frequency to overcome the effects of ionospheric delay, or using differential carrier-phase measurements in the position solution. Availability under each scenario is computed for a vertical alert limit (VAL) ranging from 5.3 m (current requirement) to 10.0 m. Results show that unless VAL is increased beyond about 5.3 m, adequate (0.999) availability cannot be achieved merely by extending the CAT I architecture or by using any one of the above methods alone, with the exception of using dual frequency in both the ground facility and the aircraft. On the other hand, if VAL can be increased to approximately 7.5 m, some other alternatives alone and most pairwise combinations of these alternatives will provide adequate availability.
Merkel cell polyomavirus (MCPyV), trichodysplasia spinulosa-associated polyomavirus (TSPyV), human polyomavirus 6 (HPyV6), and human polyomavirus 7 (HPyV7) are implicated in the pathogeneses of distinct hyperproliferative cutaneous growths and encode small tumor (sT) antigens. The current study demonstrates that the four sT antigens differentially regulate 4E-binding protein 1 (4E-BP1) serine 65 hyperphosphorylation. MCPyV and HPyV7 sT antigens were found to promote the presence of the hyperphosphorylated 4E-BP1-δ isoform, while TSPyV and HPyV6 sT antigens had no significant effects. Given that hyperphosphorylated 4E-BP1 is associated with an aggressive cancer phenotype, our findings confirm the previously reported pathogenicity of MCPyV sT and highlight a novel mechanism by which HPyV7 sT may mediate oncogenesis.
In the study of emotion recognition, relatively few e↵orts have been made to compare classification results across different emotion induction methods. In this study, we attempt to classify emotional arousal using physiological signals collected across three stimulus types-music, videos, and games. Subjects were exposed to relaxing and exciting music and videos and then asked to play Tetris and Minesweeper. Data from GSR, ECG, EOG, EEG, and PPG signals were analyzed using machine learning algorithms. We were able to successfully detect emotion arousal over a set of contiguous multimedia activities. Furthermore, we found that the patterns of physiological response to each multimedia stimuli are varying enough, that we can guess the stimulus type just by looking at the biosignals.
The Federal Aviation Administration's (FAA) Local Area Augmentation System (LAAS),
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