Search

Your search keyword '"J A Roncancio"' showing total 5 results
Start Over Author "J A Roncancio" Search Limiters Available in Library Collection
5 results on '"J A Roncancio"'

1. Evidence of a New Population of Weak Terrestrial Gamma‐Ray Flashes Observed From Aircraft Altitude

Author

I. Bjørge‐Engeland, N. Østgaard, D. Sarria, M. Marisaldi, A. Mezentsev, A. Fuglestad, N. Lehtinen, J. E. Grove, D. Shy, T. Lang, M. Quick, H. Christian, C. Schultz, R. Blakeslee, I. Adams, R. Kroodsma, G. Heymsfield, K. Ullaland, S. Yang, B. Hasan Qureshi, J. Søndergaard, B. Husa, D. Walker, M. Bateman, D. Mach, P. Bitzer, M. Fullekrug, M. Cohen, M. Stanley, S. Cummer, J. Montanya, M. Pazos, C. Velosa, O. van derVelde, Y. Pu, P. Krehbiel, J. A. Roncancio, J. A. Lopez, M. Urbani, A. Santos, T. Neubert, and F. Gordillo‐Vazquez

Subjects
terrestrial gamma‐ray flashes, lightning, ALOFT, aircraft campaign, ASIM, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract Terrestrial Gamma‐ray Flashes (TGFs) are ten‐to‐hundreds of microsecond bursts of gamma‐rays produced when electrons in strong electric fields in thunderclouds are accelerated to relativistic energies. Space instruments have observed TGFs with source photon brightness down to ∼1017–1016. Based on space and aircraft observations, TGFs have been considered rare phenomena produced in association with very few lightning discharges. Space observations associated with lightning ground observations in the radio band have indicated that there exists a population of dimmer TGFs. Here we show observations of TGFs from aircraft altitude that were not detected by a space instrument viewing the same area. The TGFs were found through Monte Carlo modeling to be associated with 1015–1012 photons at source, which is several orders of magnitude below what can be seen from space. Our results suggest that there exists a significant population of TGFs that are too weak to be observed from space.

Published
2024
Full Text
View/download PDF

2. Flickering Gamma Flashes, the Missing Link Between Gamma Glows and TGFs

Author

N Østgaard, A Mezentsev, M Marisaldi, J E Grove, M Quick, H Christian, S Cummer, M Pazos, Y Pu, M Stanley, D Sarria, T Lang, C Schultz, R Blakeslee, I Adams, R Kroodsma, G Heymsfield, N Lehtinen, K Ullaland, S Yang, B Hasan Qureshi, J Søndergaard, B Husa, D Walker, D Shy, M Bateman, P Bitzer, M Fullekrug, M Cohen, J Montanya, C Younes, O van der Velde, P Krehbiel, J A Roncancio, J A Lopez, M Urbani, A Santos, and D Mach

Subjects
Meteorology and Climatology, Space Radiation
Abstract

Two different hard radiation phenomena are known to originate from thunderclouds: Terrestrial Gamma-ray Flashes (TGFs) and gamma-ray glows. Both involve avalanche of electrons accelerated to relativistic energies but are different phenomena. Glows are known to last for one-to-hundreds of seconds, have moderate intensities and originate from quasi-stationary thundercloud fields. TGFs exhibit high intensities and have characteristic durations of tens-to-hundreds of microseconds. TGFs often show close association with emission of strong radio signals and optical pulses indicating involvement of lightning leaders in their generation. Here we report unique observations of a different phenomenon, which we call Flickering Gamma-ray Flashes (FGFs). FGFs resemble usual multi-pulse TGFs, but with larger number of pulses and each pulse has a longer duration than ordinary TGFs. FGF durations span from 20 to 250 milliseconds, which reaches the lower boundary of the gamma-ray glow duration. FGFs are radio and optically silent, which makes them distinct from normal TGFs. An FGF starts as an ordinary gamma-ray glow, then suddenly increases exponentially in intensity, and turns into an unstable, “flickering” mode with a sequence of pulses. FGFs could be the missing link between the gamma-ray glows and conventional TGFs, whose absence has been puzzling atmospheric electricity community for two decades.

Published
2024

3. Highly Dynamic Gamma-Ray Emissions Are Common in Tropical Thunderclouds

Author

M Marisaldi, N Østgaard, A Mezentsev, T Lang, J E Grove, D Shy, G M Heymsfield, P Krehbiel, R J Thomas, M Stanley, D Sarria, C Schultz, R Blakeslee, M G Quick, H Christian, I Adams, R Kroodsma, N Lehtinen, K Ullaland, S Yang, B Hasan Qureshi, J Søndergaard, B Husa, D Walker, M Bateman, D Mach, S Cummer, M Pazos, Y Pu, P Bitzer, M Fullekrug, M Cohen, J Montanya, C Younes, O van der Velde, J A Roncancio, J A Lopez, M Urbani, and A Santos

Subjects
Meteorology and Climatology
Abstract

Thunderstorms emit fluxes of gamma rays known as gamma-ray glows, sporadically observed by aircraft, balloons and from ground. Glows are observed as increased gamma-ray emissions by tens of percent up to two orders of magnitude above the background, sometimes abruptly terminated by lightning discharges. Glows are produced by the acceleration of energetic electrons in high electric field regions within thunderclouds, and contribute to charge dissipation. Glows are considered as quasi�-stationary phenomena, with durations up to a few tens of seconds and spatial scales up to 10-20 kilometers. No measurement of the full extension in space and time of a gamma� ray glow region and their occurring frequency has been reported so far. Here we show that tropical thunderclouds over ocean and coastal regions commonly emit gamma rays for hours over areas up to a few thousands of square kilometers. Emission is associated with deep convective cores; it is not uniform and continuous but shows characteristic timescales of 1-10 seconds and even sub-second for individual glows. The dynamics of gamma-glowing thunderclouds starkly contradicts the quasi-stationary picture of glows, but rather resembles that of a huge gamma-glowing «boiling pot» both in pattern and behavior.

Published
2024

4. Body weight in relation to hours of sleep, and physical activity in Latin American university students during the Covid-19 pandemic

Author

Eliana Romina Meza-Miranda, Solange Liliana Parra-Soto, Samuel Durán-Agüero, Georgina Gomez, Valeria Carpio-Arias, Israel Ríos-Castillo, Ana Gabriela Murillo, Jacqueline Araneda, Gladys Morales, Brian M. Cavagnari, Edna J. Nava-González, Jhon J. Bejarano-Roncancio, Beatriz Núñez, Karla Cordón-Arrivillaga, Saby Mauricio-Alza, and Leslie Landaeta-Díaz

Subjects
ESTUDIANTES UNIVERSITARIOS, DESCANSO, INACTIVIDAD FISICA, Public Health, Environmental and Occupational Health, Physical exercise, COVID-19, AUMENTO DE PESO, Sleep quality, PANDEMIA, CONFINAMIENTO, PESO CORPORAL, EJERCICIO FISICO, SALUD, Weight gain, SUEÑO
Abstract

Fil: Meza Miranda, Eliana Romina. Universidad Nacional de Asunción. Centro Multidisciplinario de Investigaciones Tecnológicas; Paraguay Fil: Parra Soto, Solange Liliana. University of Glasgow. Institute of Cardiovascular and Medical Sciences. Glasgow Cardiovascular Research Centre; Reino Unido Fil: Parra Soto, Solange Liliana. University of Glasgow. Institute of Health and Wellbeing; Reino Unido Fil: Durán Agüero, Samuel. Universidad San Sebastián. Facultad de Ciencias para el Cuidado de la Salud. Escuela de Nutrición y Dietética; Chile Fil: Gómez, Georgina. Universidad de Costa Rica; Costa Rica Fil: Carpio Arias, Valeria. Escuela Superior Politecnica de Chimborazo. Facultad de Salud Pública. Grupo de Investigación en Alimentación y Nutrición Humana; Ecuador Fil: Ríos Castillo, Israel. Organización de las Naciones Unidas para la Alimentación y la Agricultura. Oficina Subregional para Mesoamérica; Panamá Fil: Araneda, Jacqueline. Universidad del Bío-Bío. Facultad de Ciencias de la Salud y de los Alimentos. Departamento de Nutrición y Salud Pública; Chile; Fil: Morales, Gladys. Universidad de La Frontera. Facultad de Medicina. Departamento de Salud Pública; Chile Fil: Morales, Gladys. Universidad de La Frontera. Centro de Investigación en Epidemiología Cardiovascular y Nutricional; Chile Fil: Cavagnari, Brian M. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Escuela de Nutrición; Argentina Fil: Nava González, Edna J. Universidad Autónoma de Nuevo León. Facultad de Salud Pública y Nutrición; México Fil: Bejarano Roncancio, Jhon J. Universidad Nacional de Colombia. Facultad de Medicina. Departamento de Nutrición Humana; Colombia Fil: Núñez, Beatriz. Universidad Autónoma de Asunción; Paraguay Fil: Cordón Arrivillaga, Karla. Universidad de San Carlos de Guatemala. Facultad de Ciencias Químicas y Farmacia. Unidad de Investigación en Seguridad Alimentaria y Nutricional Escuela de Nutrición; Guatemala Fil: Mauricio Alza, Saby. Universidad Privada Norbert Wiener; Perú Fil: Landaeta Díaz, Leslie. Universidad de Las Américas. Facultad de Salud y Ciencias sociales; Chile Abstract: Introduction: Short sleep, physical inactivity, and being locked up are risk factors for weight gain. Objective: We evaluated weight gain according to sex, age, hours of sleep and physical activity in university students from 10 Latin American countries during the COVID-19 pandemic. Methods: Cross-sectional and multicenter study (n = 4880). Results: The average age was 22.5 ± 4.4 years. 60.2% were currently locked up. 73.6% were women, 48.2% increased their body weight, 66% reported insufficient sleep hours, and 65.9% were inactive. Women gained more weight than men (73.2%) and younger students gained more weight (85.1%). Those who had insufficient sleep hours gained most weight (67.6%). Inactive participants gained most weight (74.7%). Students who have insufficient sleep are 21% more likely to have changes in body weight compared to students who have optimal sleep. Conclusion: The increase in body weight and its risk factors during confinement should be considered as emerging from public health.

Published
2022

5. Como acelerar uniformemente Ia floración en solidaster (Solidago x luteus).

Author

Víctor J. Flórez-Roncancio y and Maria de Fátima A. D. Pereira

Subjects
Plant culture, SB1-1110
Abstract

Solidaster (Solidago x luteus) es un híbrido interespecífico entre Solidago ptarmicoides y Solidago canadensis. Son plantas típicas de dias largos (DL), las cuales, dependiendo de la temperatura, crecen como rosetas en dias curtos (DC). Estas plantas son cultivadas para flor de corte. Se observaron características vegetativas y reproductivas de este híbrido en condiciones fotoperiódicas de 8h y 20h y se realizaron estudios de comportamiento fotoperiódico del desarrollo desde el botón floral hasta antesis. Tanto en DL como en DC se observó inducción y antesis floral; mientras que, en DL se verifico mayor altura de planta y aumento en el número de ramificaciones laterales, en DC se observó antesis floral más rápida. La evidencia de que los DC aceleraban la antesis floral, en plantas inducidas en días largos, se fortalecia con el experimento de diferente duración en días cortos (5; 10 y 15 días); lo cual se confirmó en experimentos subsecuentes, cuando se comprobó que la planta responde a los fotoperíodos cortos (8h; 10h y 12h), acelerando Ia antesis y a los fotoperíodos largos (16h y 20h), retardándoIa. Los fotoperíodos entre 12h y 16h (14h) estarían en una situación de transición entre DC y DL, caracterizando, así, una respuesta cuantitativa con el aumento del fotoperíodo.

Published
1999
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results