Ricki Sheldon - Academia.edu (original) (raw)
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Papers by Ricki Sheldon
Springer eBooks, Oct 1, 2022
Previous epidemiological studies have shown that the incidence and severity of COVID-19 decrease ... more Previous epidemiological studies have shown that the incidence and severity of COVID-19 decrease significantly with high altitude. To date, the impact of high altitude on mortality caused by COVID-19 remains debated. This work evaluated the impact of high altitude residency on COVID-19 mortality and recovery rates in several Andean countries and México. For this purpose, a multinational ecological study of official data from Bolivia, Peru, Colombia, Ecuador, and Mexico was performed from the beginning of the pandemic until the end of 2020. The case fatality rate (CFR) of populations above 2,500 m and below 1,000 m was compared. Our results show that CFR decreases, and there is a higher recovery rate in populations located above 2,500 m in all five countries. Based on this study and multiple other references, we conclude that mortality caused by COVID-19 is lower in high-altitude Andean populations, and in the high-altitude municipalities of Mexico than in the lowlands of all these c...
Springer Publishing Company eBooks, Oct 1, 2022
This paper reports multiplatform observations of leader radiation preceding initial cloud-to-grou... more This paper reports multiplatform observations of leader radiation preceding initial cloud-to-ground lightning return strokes by <6 ms. Specifically, we present multistation ground-based LF/VLF recordings of events with large-amplitude leader activity (comparable in amplitude to the return stroke amplitude). The events were selected for their coincidence with VHF observations by the FORTE satellite. Some FORTE VHF leader step observations have obvious direct and ground reflection components. For these steps, which temporally correspond to specific features in the ground LF/VLF field change records, we calculate a source height based on event satellite geometry. We determine source heights between 4.0 and 5.5 km. For FORTE records with multiple reflected events we calculate vertical leader propagation velocities on the order of 10 6 m/s. The determined vertical leader propagation speeds are an order of magnitude greater than those reported as typical values for stepped leader velocities associated with initial return strokes.
Journal of Geophysical Research, 2002
This paper reports multiplatform observations of leader radiation preceding initial cloud-to-grou... more This paper reports multiplatform observations of leader radiation preceding initial cloud-to-ground lightning return strokes by <6 ms. Specifically, we present multistation ground-based LF/VLF recordings of events with large-amplitude leader activity (comparable in amplitude to the return stroke amplitude). The events were selected for their coincidence with VHF observations by the FORTE satellite. Some FORTE VHF leader step observations have obvious direct and ground reflection components. For these steps, which temporally correspond to specific features in the ground LF/VLF field change records, we calculate a source height based on event satellite geometry. We determine source heights between 4.0 and 5.5 km. For FORTE records with multiple reflected events we calculate vertical leader propagation velocities on the order of 10 6 m/s. The determined vertical leader propagation speeds are an order of magnitude greater than those reported as typical values for stepped leader velocities associated with initial return strokes.
Springer eBooks, Oct 1, 2022
Previous epidemiological studies have shown that the incidence and severity of COVID-19 decrease ... more Previous epidemiological studies have shown that the incidence and severity of COVID-19 decrease significantly with high altitude. To date, the impact of high altitude on mortality caused by COVID-19 remains debated. This work evaluated the impact of high altitude residency on COVID-19 mortality and recovery rates in several Andean countries and México. For this purpose, a multinational ecological study of official data from Bolivia, Peru, Colombia, Ecuador, and Mexico was performed from the beginning of the pandemic until the end of 2020. The case fatality rate (CFR) of populations above 2,500 m and below 1,000 m was compared. Our results show that CFR decreases, and there is a higher recovery rate in populations located above 2,500 m in all five countries. Based on this study and multiple other references, we conclude that mortality caused by COVID-19 is lower in high-altitude Andean populations, and in the high-altitude municipalities of Mexico than in the lowlands of all these c...
Springer Publishing Company eBooks, Oct 1, 2022
This paper reports multiplatform observations of leader radiation preceding initial cloud-to-grou... more This paper reports multiplatform observations of leader radiation preceding initial cloud-to-ground lightning return strokes by <6 ms. Specifically, we present multistation ground-based LF/VLF recordings of events with large-amplitude leader activity (comparable in amplitude to the return stroke amplitude). The events were selected for their coincidence with VHF observations by the FORTE satellite. Some FORTE VHF leader step observations have obvious direct and ground reflection components. For these steps, which temporally correspond to specific features in the ground LF/VLF field change records, we calculate a source height based on event satellite geometry. We determine source heights between 4.0 and 5.5 km. For FORTE records with multiple reflected events we calculate vertical leader propagation velocities on the order of 10 6 m/s. The determined vertical leader propagation speeds are an order of magnitude greater than those reported as typical values for stepped leader velocities associated with initial return strokes.
Journal of Geophysical Research, 2002
This paper reports multiplatform observations of leader radiation preceding initial cloud-to-grou... more This paper reports multiplatform observations of leader radiation preceding initial cloud-to-ground lightning return strokes by <6 ms. Specifically, we present multistation ground-based LF/VLF recordings of events with large-amplitude leader activity (comparable in amplitude to the return stroke amplitude). The events were selected for their coincidence with VHF observations by the FORTE satellite. Some FORTE VHF leader step observations have obvious direct and ground reflection components. For these steps, which temporally correspond to specific features in the ground LF/VLF field change records, we calculate a source height based on event satellite geometry. We determine source heights between 4.0 and 5.5 km. For FORTE records with multiple reflected events we calculate vertical leader propagation velocities on the order of 10 6 m/s. The determined vertical leader propagation speeds are an order of magnitude greater than those reported as typical values for stepped leader velocities associated with initial return strokes.