Multi-instrumental analysis of large sprite events and their producing storm in southern France

During the night of 01-02 September, 2009, seventeen distinct sprite events including 3 halos were observed above a storm in north-western Mediterranean Sea, with a video camera at Pic du Midi (42.93N; 0.14E; 2877m). The sprites occurred at distances between 280 and 390km which are estimated based on their parent CG location. The MCS-type storm was characterized by a trailing-stratiform structure and a very circular shape with a size of about 70,000km2 (cloud top temperature lower than -35°C) when the TLEs were observed. The cloud to ground (CG) flash rate was large (45min-1) one hour before the TLE observation and very low (<5min-1) during it. Out of the 17 sprite events, 15 parent+CG (P+CG) strokes have been identified and their average peak current is 87kA (67kA for the 14 events without halo), while the associated charge moment changes (CMC) that could be determined, range from 424 to 2088±20%Ckm. Several 2-second videos contain multiple sprite events: one with four events, one with three events and three with two events. Column and carrot type sprites are identified, either together or separately. All P+CG strokes are clearly located within the stratiform region of the storm and the second P+CG stroke of a multiple event is back within the stratiform region. Groups of large and bright carrots reach ~70km height and ~80km horizontal extent. These groups are associated with a second pulse of electric field radiation in the ELF range which occurs ~5ms after the P+CG stroke and exhibits the same polarity, which is evidence for current in the sprite body. VLF perturbations associated with the sprite events were recorded with a station in Algiers. © 2012 Elsevier B.V

Autonomic nervous system assessment in critically ill patients undergoing a cognitive rehabilitation therapy

Recent clinical and electrophysiological studies reveal a high incidence of autonomic nervous system (ANS) dysfunction in patients treated in Intensive Care Units (ICUs). Cognitive rehabilitation (CR) is a behavioral therapy that has proven to be effective improving cognitive deficits in clinical populations with abnormalities in brain activation patterns. A total of 17 critically ill patients received CR aimed to improve the ANS status, which was quantified in terms of HRV. The CR included cognitive exercises aimed to improve prefrontal activation. HRV was obtained during pre-CR, CR and post-CR. Power in the low (PLF) and high (PHF) frequency bands related to sympathetic and parasympathetic systems was computed. PHF was obtained within a band centered at respiratory rate. Comparing with baseline values, 7 patients showed an increased PHF in post-CR, suggesting an increase of parasympathetic activity

Polarimetric radar characteristics of lightning initiation and propagating channels

In this paper we present an analysis of a large dataset of lightning and polarimetric weather radar data collected in the course of a lightning measurement campaign that took place in the summer of 2017 in the area surrounding Säntis, in the northeastern part of Switzerland. For this campaign and for the first time in the Alps, a lightning mapping array (LMA) was deployed. The main objective of the campaign was to study the atmospheric conditions leading to lightning production with a particular focus on the lightning discharges generated due to the presence of the 124¿m tall Säntis telecommunications tower. In this paper we relate LMA very high frequency (VHF) sources data with co-located radar data in order to characterise the main features (location, timing, polarimetric signatures, etc.) of both the flash origin and its propagation path. We provide this type of analysis first for all of the data and then we separate the datasets into intra-cloud and cloud-to-ground flashes (and within this category positive and negative flashes) and also upward lightning. We show that polarimetric weather radar data can be helpful in determining regions where lightning is more likely to occur but that lightning climatology and/or knowledge of the orography and man-made structures is also relevant.Peer ReviewedPostprint (author's final draft

Effect of an early neurocognitive rehabilitation on autonomic nervous system in critically ill patients

Introduction Recent clinical and electrophysiological studies reveal a high incidence of autonomic nervous system (ANS) dys- function in patients treated in ICU [1]. ANS disturbances may produce diverse and unexpected consequences. For instance, critically ill patients are at risk of neurocognitive impairments that may persist after hospital discharge. Among various pathophysiological mechanisms proposed, ANS dysfunction leading cholinergic deficiency seems one of the most viable to explain the development of long-term sequelae. Heart rate variability (HRV) has been related to the activity of the prefrontal cortex [2] hence, prefrontal activation could help to strengthen the auto- nomic nervous system integrity. We are interested in assessing the improvement of the ANS dysfunction through neural circuits’ activation. Thus, we propose a novel therapy that could allow the reinforcing of ANS through an early neurocognitive intervention targeted to improve prefrontal activation. Objectives The aim of this study was to explore if the integrity of the ANS, via cardiac vagal tone, measured by the HRV can be modified after early neurocognitive rehabilitation in ICU patients. Methods A total of 17 critically ill patients received a 20-minute Early Neurocognitive Rehabilitation (ENR) session in their own bed in the ICU. HRV was derived from the recorded ECG signal during pre-session, session and post-session. Power in the specific frequency bands related to sympathetic and parasympathetic systems was computed (PLF and PHF for low and high frequency bands, respectively). PLF was computed within the clas- sic band, while PHF was computed within a band cen- tered at respiratory rate. Changes in the HRV parameters from pre-session to session, and from pre- session to post-session were studied using Wilcoxon signed-rank test. Results Clinical data of the sample are summarized in table 1. Comparing with baseline values, 9 patients (53%) showed a decreased PLF in post-session, while 8 patients (47%) presented a higher PLF (p = .759). In 12 patients (71%), PHF increased after the ENR session, suggesting an increase of parasympathetic activity (p = .836). Conclusions Diagnosis, severity of illness or medication could explain the differential effect in the evolution of the HRV para- meters among different patients. Despite differences, an early neurocognitive rehabilitation seems to increase parasympathetic activity after the session in the majority of the patients. Clinical characteristics of the critical ill patients should be further studied to determinate which patients could be the best candidates for early neurocog- nitive intervention

Initiation of lightning flashes simultaneously observed from space and the ground: Narrow bipolar events

We investigate the initiation of four lightning flashes detected from ground by means of the Colombia Lightning Mapping Array (Colombia-LMA) and simultaneously observed from space by the optical sensors of the Atmosphere-Space Interactions Monitor (ASIM) on board the International Space Station (ISS), the Geostationary Lightning Mapper (GLM), and the Lightning Imaging Sensor on the ISS. The initiations of the flashes are characterized by isolated and predominant optical blue pulses (337.0 nm). In three of the flashes, red emissions (777.4 nm), a dominant line of hot lightning, were not detected during their initiation. In these cases, the initiations were also accompanied by bipolar VLF/LF waveform with a narrow short duration (<40 μs) and VHF emissions with high radio frequency power (<269 kW). The detection of the blue emissions without any red luminosity supports that the fast breakdown processes at the flash initiation can be exclusively of streamer nature. The onset of the fourth flash was associated with both blue and red radiation, and with weak narrow bipolar waveform in VLF/LF and low VHF power. The flashes initiated between the midlevel negative and upper positive charge regions. This paper presents and discusses the first fast breakdown processes observed simultaneously from ground by means a Lightning Mapping Array (LMA) and from space during the onset of lightning flashes.publishedVersio

Characteristics and conditions of production of transient luminous events observed over a maritime storm

International audienceOn the night of 15/16 November 2007, cameras in southern France detected 30 transient luminous events (TLEs) over a storm located in the Corsican region (France). Among these TLEs, 19 were sprites, 6 were halos, and 5 were elves. For 26 of them, a positive “parent” cloud‐to‐ground lightning (P+CG) flash was identified. The peak current of the P+CG flashes for the sprites had an average value of 63 kA and had a maximum value of 125 kA. The flashes for the halos and the elves had average values of 272 and 351 kA, respectively, and they had maximum values of 312 and 384 kA, respectively. No TLEs were detected after negative CG flashes with very large peak currents. Among the 26 P+CG flashes, 23 were located in a stratiform region with reflectivity values lower than 45 dBZ. The CG flashes in this region were classified into two groups according to the time interval separating them from the following flash: one group with values less than 2 s and one with values greater than 2 s. About 79% of all CGs were produced in a sequence of at least two flashes less than 2 s apart. For 65.5% of the sequences, the first flash was positive with an average peak current of 73 kA, while the later +CG flashes in a sequence had much lower peak currents. Several triangulated sprites were found to be shifted from their P+CG flashes by about 10 to 50 km and preferentially downstream. The observations suggest that the P+CG flashes can initiate both sprites and other CG flashes in a storm

Large meteoroids from the 2P/Encke complex : orbital data of 2010 taurids recorded in the framework of the Spanish fireball network

Cometary disruptions are though to be an important source of Near Earth Objects (heareafter NEOs). A continuous monitoring of meteor showers from multistation networks on the ground allows to get valuable orbital information of large meteoroids producing fireballs. From such orbits can be established conections with the orbital elements of diferent asteroids or comets. In 2010 we started a program to get precise orbital information of very bright Taurid bolides in order to try to identify possible associations with members of the NEO population [1]. We have already identified some meteoroids that could be dynamically associated with some NEOs currently identified as members of the Taurid complex. This group of bodies is formed by about 20 NEOs that presumably formed by the fragmentation of a giant comet over the past 20-30 kyr [2-4]. Some of these bodies have orbital affinities to comet 2P/Encke, but recent studies have found other asteroids in Apollo-like orbits that can be good candidates to trace a progressive cometary disruption that at different stages as a by-product produced the Taurid meteoroid branches [3, 4]. It is important to remark that the NEOs associated with the Taurid meteoroid streams are presumably dark, as seems to confirm the spectral information obtained for the largests members (e.g. 16960 belongs to the B spectral class [5]). Consequently these bodies are among the most difficult and hazardous NEOs that remain to be discovered. In fact, the Tunguska object has been temptatively associated with the Taurid complex [6]. A recent paper also links the Earth’s intersection with the debris produced by the disruption of the cometary progenitor with a possible Palaeolithic extinction occurred around 12,900 BP [7]. Our orbital studies of Taurid meteoroids could also identify other members of the complex by using association criteria and backwards integration of their orbits. In fact we have found some Taurid complex members that are exhibiting orbits not directly linked with the two main branches. Obviously, having the Taurid complex some members with about 100 meters in diameter [4], we suspect of the existence of much more bodies in such a range of sizes not discovered yet. These objects could also produce meteorite-droping bolides in determinate favourable geometric circumstances [1]

Initiation of lightning flashes simultaneously observed from space and the ground: Narrow bipolar events

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).We investigate the initiation of four lightning flashes detected from ground by means of the Colombia Lightning Mapping Array (Colombia-LMA) and simultaneously observed from space by the optical sensors of the Atmosphere-Space Interactions Monitor (ASIM) on board the International Space Station (ISS), the Geostationary Lightning Mapper (GLM), and the Lightning Imaging Sensor on the ISS. The initiations of the flashes are characterized by isolated and predominant optical blue pulses (337.0 nm). In three of the flashes, red emissions (777.4 nm), a dominant line of hot lightning, were not detected during their initiation. In these cases, the initiations were also accompanied by bipolar VLF/LF waveform with a narrow short duration (<40 μs) and VHF emissions with high radio frequency power (<269 kW). The detection of the blue emissions without any red luminosity supports that the fast breakdown processes at the flash initiation can be exclusively of streamer nature. The onset of the fourth flash was associated with both blue and red radiation, and with weak narrow bipolar waveform in VLF/LF and low VHF power. The flashes initiated between the midlevel negative and upper positive charge regions. This paper presents and discusses the first fast breakdown processes observed simultaneously from ground by means a Lightning Mapping Array (LMA) and from space during the onset of lightning flashes. © 2021 The Authors.The UPC contribution: This work was supported by research Grants ESP2013-48032-C5-3-R, ESP2015-69909-C5-5-R and ESP2017-86263-C4-2-R funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, by the “European Union”; and Grant PID2019-109269RB-C42 funded by MCIN/AEI/ 10.13039/501100011033. The IAA contribution: This work was supported by the Spanish Ministry of Science and Innovation, Ministerio de Ciencia e Innovación (AEI) under project PID2019-109269RB-C43 and the FEDER program. FJPI acknowledges the sponsorship provided by the Federal Ministry for Education and Research of Germany through the Alexander von Humboldt Foundation. AL was supported by the European Research Council (ERC) under European Union Horizon 2020 Framework Programme/ERC Grant Agreement 681257. Authors FJGV, FJPI, and AL acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV- 2017-0709). The UV contribution: This work was supported by research grants from the Spanish Ministry of Economy and the European Regional Development Fund (FEDER): ESP2013-48032-C5-1-R, ESP2015-69909-C5-1-R and ESP2017-86263-C4-1-R. The UB (University of Bergen) would like to thank the Research Council of Norway under contracts 223252/F50 (CoE). The USP (University of Sao Paulo) contribution: This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)— Print Project (grant number: 88887.370081/2019-00). ASIM is a mission of The European Space Agency (ESA). The project is funded by ESA and by national grants of Denmark, Norway, and Spain. We thank Keraunos(Colombia) for the LINET data.Peer reviewe