Recent studies of thunderstorm-related enhancements of fluxes of energetic radiation and particles at ground level suggest that removal of mid-level negative charge from the cloud by negative ...cloud-to-ground (-CG) lightning flashes or normal intracloud (IC) flashes serves to abruptly terminate those enhancements. However, it was not clear if the electron-accelerating electric field responsible for flux enhancements at ground was primarily between the main negative charge region and ground (produced due to the dominant effect of negative cloud charge) or between the mid-level negative and lower positive charge regions inside the thundercloud. Here, we report that these flux enhancements can be also abruptly terminated by inverted intracloud flashes and hybrid lightning flashes (inverted IC followed by negative CG). Based on the analysis of 13 events of these two types, we provide first evidence that the electric field between the mid-level negative and lower positive charge regions in the thundercloud can be responsible for the flux enhancements at ground level.
•Lightning discharges can influence the evolution of enhanced fluxes of energetic radiation and particles (TGEs).•TGEs can be abruptly terminated by inverted intracloud flashes (ICs) and by hybrid flashes (inverted IC followed by -CG).•Electron accelerator between main negative and lower positive cloud charge regions is capable of producing TGEs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The problem of thundercloud electrification is one of the most difficult ones in atmospheric physics. The structure of electric fields in clouds escapes from the detailed in situ measurements; few ...balloon flights reveal these rather complicated structures. To gain insight into the problem of the charge structure of a thundercloud, we use new key evidence-the fluxes of particles from a thundercloud, the so-called thunderstorm ground enhancements-TGEs. TGEs originate from electron acceleration and multiplication processes in the strong electric fields in the thundercloud, and the intensity and energy spectra of electrons and gamma rays as observed on the Earth’s surface are directly connected with the atmospheric electric field. Discovery of long-lasing TGEs poses new challenges for revealing structures in the thundercloud responsible for hours-extending gamma ray fluxes. In the presented paper, we demonstrate that experimentally measured intensities and energy spectra of the “thundercloud particles” give clues for understanding charge structures embedded in the atmosphere. A rather short “runaway” process above the detector site, which is consistent with the tripole structure of the cloud electrification, is changing to a much less energetic emission that lasts for hours. Measurements of enhanced particle fluxes are accompanied by the simulation experiments with corsika and geant4 codes.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We present ground‐based measurements of thunderstorm‐related enhancements of fluxes of energetic radiation and particles that are abruptly terminated by lightning discharges. All measurements were ...performed at an altitude of 3200 m above sea level on Mount Aragats (Armenia). Lightning signatures were recorded using a wideband electric field measuring system with a useful frequency bandwidth of 50 Hz to 12 MHz and network of five electric field mills, three of which were installed at the Aragats station, one at the Nor Amberd station (12.8 km from Aragats), and one at the Yerevan station (39 km from Aragats). We observed that the flux‐enhancement termination was associated only with close (within 10 km or so of the particle detector) negative CGs and normal‐polarity ICs; that is, with lightning types which reduce the upward directed electric field below the cloud and hence suppress the acceleration of electrons toward the ground.
Key Points
Lightning discharges can influence the evolution of enhanced fluxes of energetic radiation and particles (TGEs)
Only negative CGs and normal‐polarity ICs were observed to abruptly terminate TGEs
All TGEs occurred when the downward electron‐accelerating electric field was present, at least for a portion of their duration
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We present the observational data on registration of atmospheric discharges simultaneously with the detection of elementary particles obtained during thunderstorms at an altitude of 3200 m above sea ...level on Mt. Aragats in Armenia. Throughout the 2016 summer and 2018 spring campaigns on Aragats, we monitored lightning occurrences and signals from NaI spectrometers, plastic scintillators and Neutron Monitor proportional counters, and analyzed the shape of registered pulses. Particle detector signals were synchronized with lightning occurrences at a few nanoseconds level.
Analysis of shapes of the simultaneously detected pulses of the fast wideband electric field produced by a lightning flash and pulses from particle detectors discloses that all additional detector pulses registered during lightning flash were the electromagnetic interference signals and not particles originated directly from the lightning bolt. Thus, we observe no evidence of the direct production of electrons, neutrons or gamma rays during a lightning flash. We conclude that the entire particle fluxes detected on Aragats research station (more than 250 TGEs) can be explained by the generation of MeV electromagnetic cascades in the strong atmospheric electric fields.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Postoperative nausea and vomiting (PONV) is a commonly encountered problem in surgical practice. It delays discharge from the post-anesthesia care unit, requires additional resources to treat, and ...may increase the morbidity in some patients. Many effective drugs are available to treat or prevent PONV, however many of these drugs have the potential to prolong the QTc on the electrocardiogram (EKG) and increase the risk of serious ventricular arrhythmias, in particular, torsade de pointes. The QTc prolongation may be a manifestation of a genetic mutation resulting in abnormal myocyte repolarization or it may be acquired and associated with the use of various medications, electrolyte disorders, and physiological conditions. Patients predisposed to QTc prolongation presenting for surgery constitute a challenging group, since many drugs commonly used for PONV management will put them at risk for perioperative serious arrhythmias. This is an important topic, and our mini-review is an attempt to highlight the problem, summarize the existing experience, and generate recommendations for safe management of PONV for patients, who are at increased risk of QTc prolongation and arrhythmias. Focused prospective studies will help to find definitive answers to the discussed problems and challenges and develop specific guidelines for clinical application.
Abstract
We present the facilities of the Aragats Space Environmental Center in Armenia used during multi-year observations of the thunderstorm ground enhancements (TGEs) and corresponding ...environmental parameters. We analyze the characteristics of the detectors, operated on Aragats, and describe the coordinated detection of TGEs by the network of scintillators, field meters, and weather stations. By using a fast synchronized data acquisition system, we reveal correlations of the multivariate data on time scales from nanoseconds to minutes, which allow us to gain insight into the TGE and lightning origin and their interrelations. Also, we demonstrate how different coincidences of multilayered detector operation can select various species of secondary cosmic rays.
A broadband radio interferometer for locating lightning emissions was built and deployed at the high-altitude research station on Mount Aragats (Armenia). The instrument operates in the frequency ...range from 24 to 78 MHz and employs three identical broadband flat-plate antennas which are located in the horizontal plane and form two orthogonal baselines of 13 m length. The time differences of arrival of the signals at pairs of antennas determined from the peak of the cross-correlation function are used to measure the azimuth and elevation angles of the radiation source as a function of time. This paper describes the operation of the interferometer and reports observations of lightning flashes complemented by synchronous measurements of fast wideband electric field waveforms and changes in the near-surface electrostatic field. Combined analysis of these data makes it possible to identify the type of lightning discharge. The capability of the system to classify lightning types is demonstrated by example observations of an intracloud and a cloud-to-ground lightning flashes.
Purpose of the article: To determine whether intraoperative ventilation with pure oxygen during the last stage of surgery reduces the occurrence and volume of postoperative pneumocephalus when ...compared to conventional air/oxygen mixture in patients undergoing craniotomy.
Material and Methods: prospective randomized single-blinded study to compare the rate of occurrence and volume of postoperative pneumocephalus in patients undergoing craniotomy receiving intraoperative ventilation with pure oxygen (Group B) versus a conventional air/oxygen 1:1 mixture (Group A) during the last stage of surgery. This trial was registered in ClinicalTrials.gov #NCT02722928, protocol number 2015H0032.
Results: One hundred patients were randomized into group 'A' and group 'B'. Seventy patients were included in the final analysis with 39 patients allocated in group 'A' and 31 patients in group 'B'. Median and IQR were used for postoperative penumocephalus volume. Group A: 9.65 3.61-23.20; Group B: 7.06 2.70-20.1. Our study showed no prophylactic effect on postoperative pneumocephalus volume when using mechanical ventilation with higher oxygen concentrations than the standard FiO
2
during the last stage of surgery in patients undergoing craniotomy (p = .47). No statistical difference was found in SICU LOS between groups (median 1,380 min group A versus 1,524 min group B; p = .18).
Conclusion: The use of intraoperative mechanical ventilation with pure oxygen was not associated with a prophylactic effect on the occurrence and extent of postoperative pneumocephalus in our patient setting. Published literature describing the extent of postoperative pneumocephalus is limited or highly variable among institutions.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Thermal lens in Nd3+:YVO4/LiNbO3 microchip green laser affects stability and working regimes of the laser. Absence of any passive or active Q-switching and mode locking make the thermal lens the only ...method to affect working regimes and stability of the laser cavity, which is composed of planar active and nonlinear mediums. Thus, investigation of thermal lens is crucial for the optimization of working regimes of the microchip laser.
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