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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.

The emerging field of high-energy atmospheric physics studies how high-energy particles are produced in thunderstorms, in the form of terrestrial γ-ray flashes and γ-ray glows (also referred to as thunderstorm ground enhancements). Understanding these phenomena requires appropriate models of the interaction of electrons, positrons and photons with air molecules and electric fields. We investigated the results of three codes used in the community – Geant4, GRanada Relativistic Runaway simulator (GRRR) and Runaway Electron Avalanche Model (REAM) – to simulate relativistic runaway electron avalanches (RREAs). This work continues the study of Rutjes et al. (2016), now also including the effects of uniform electric fields, up to the classical breakdown field, which is about 3.0 MV m−1 at standard temperature and pressure.We first present our theoretical description of the RREA process, which is based on and incremented over previous published works. This analysis confirmed that the avalanche is mainly driven by electric fields and the ionisation and scattering processes determining the minimum energy of electrons that can run away, which was found to be above ≈ 10 keV for any fields up to the classical breakdown field.To investigate this point further, we then evaluated the probability to produce a RREA as a function of the initial electron energy and of the magnitude of the electric field. We found that the stepping methodology in the particle simulation has to be set up very carefully in Geant4. For example, a too-large step size can lead to an avalanche probability reduced by a factor of 10 or to a 40 % overestimation of the average electron energy. When properly set up, both Geant4 models show an overall good agreement (within ≈ 10 %) with REAM and GRRR. Furthermore, the probability that particles below 10 keV accelerate and participate in the high-energy radiation is found to be negligible for electric fields below the classical breakdown value. The added value of accurately tracking low-energy particles (−1.In a second simulation set-up, we compared the physical characteristics of the avalanches produced by the four models: avalanche (time and length) scales, convergence time to a self-similar state and energy spectra of photons and electrons. The two Geant4 models and REAM showed good agreement on all parameters we tested. GRRR was also found to be consistent with the other codes, except for the electron energy spectra. That is probably because GRRR does not include straggling for the radiative and ionisation energy losses; hence, implementing these two processes is of primary importance to produce accurate RREA spectra. Including precise modelling of the interactions of particles below 10 keV (e.g. by taking into account molecular binding energy of secondary electrons for impact ionisation) also produced only small differences in the recorded spectra.

With a launch expected in 2018, the TARANIS microsatellite is dedicated to the study of transient phenomena observed in association with thunderstorms. On board the spacecraft, XGRE and IDEE are two instruments dedicated to studying terrestrial gamma-ray flashes (TGFs) and associated terrestrial electron beams (TEBs). XGRE can detect electrons (energy range: 1 to 10 MeV) and X- and gamma-rays (energy range: 20 keV to 10 MeV) with a very high counting capability (about 10 million counts per second) and the ability to discriminate one type of particle from another. The IDEE instrument is focused on electrons in the 80 keV to 4 MeV energy range, with the ability to estimate their pitch angles. Monte Carlo simulations of the TARANIS instruments, using a preliminary model of the spacecraft, allow sensitive area estimates for both instruments. This leads to an averaged effective area of 425 cm2 for XGRE, used to detect X- and gamma-rays from TGFs, and the combination of XGRE and IDEE gives an average effective area of 255 cm2 which can be used to detect electrons/positrons from TEBs. We then compare these performances to RHESSI, AGILE and Fermi GBM, using data extracted from literature for the TGF case and with the help of Monte Carlo simulations of their mass models for the TEB case. Combining this data with the help of the MC-PEPTITA Monte Carlo simulations of TGF propagation in the atmosphere, we build a self-consistent model of the TGF and TEB detection rates of RHESSI, AGILE and Fermi. It can then be used to estimate that TARANIS should detect about 200 TGFs yr−1 and 25 TEBs yr−1.

The emerging field of high energy atmospheric physics (HEAP) includes terrestrial gamma-ray flashes, electron–positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy atmospheric physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.

O resfriamento e/ou congelamento de produtos hortícolas, depois da colheita, é realizado com o objetivo de retirar o calor desses produtos, permitindo-lhes, em função disso, um tempo maior de conservação. Portanto, o conhecimento das propriedades físicas que envolvem transferência de calor do figo "Roxo de Valinhos" é útil para o cálculo de projetos e a análise de sistemas de engenharia de alimentos em geral, assim como para o emprego em equações de modelos matemáticos termodinâmicos. Neste trabalho, foram determinadas, experimentalmente, a condutividade e a difusividade térmica do figo inteiro no estádio rami e, a partir desses valores, foi determinado o calor específico. Foi utilizado o método transiente da Fonte Linear de Calor. Foi introduzida nas frutas uma sonda que contém resistência elétrica e termopares. Para manter constante a temperatura da fruta, montou-se um sistema de resfriamento a água. Encontrou-se que o figo rami apresentou um valor de condutividade térmica de 0,52 W m-1 °C, difusividade térmica de 1,56 x 10-7 m² s-1, massa específica do figo de 815,6 kg m-3 e calor específico de 4,07 kJ kg-1 °C.The post harvest cooling and/or freezing processes for horticultural products have been carried out with the objective of removing the heat from these products, allowing them a bigger period of conservation. Therefore, the knowledge of the physical properties that involve heat transference in the fig fruit "Roxo de Valinhos" is useful for calculating projects and systems of food engineering in general, as well as, for using in equations of thermodynamic mathematical models. The values of conductivity and thermal diffusivity of the whole fig fruit-rami index were determined, and from these values it was determined the value of the specific heat. For these determination it was used the transient method of the Line Heat Source. The results shown that the fig fruit has a thermal conductivity of 0.52 W m-1°C, thermal diffusivity of 1.56 x 10-7 m² s-1, pulp density of 815.6 kg m-3 and specific heat of 4.07 kJ kg-1 °C.

Thunderstorms emit fluxes of gamma rays known as gamma-ray glows 1,2 , sporadically observed by aircraft 1,3-7 , balloons 8-11 and from the ground 12-18 . Observations report increased gamma-ray emissions by tens of percent up to two orders of magnitude above the background, sometimes abruptly terminated by lightning discharges 1,3-5 . Glows are produced by the acceleration of energetic electrons in high-electric-field regions within thunderclouds 8 and contribute to charge dissipation 3 . Glows had been considered as quasi-stationary phenomena 3,5,12 , with durations up to a few tens of seconds and spatial scales up to 10-20 km. However, no measurements of the full extension in space and time of a gamma-ray-glow region and their occurring frequency have 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 thousand square kilometres. Emission is associated with deep convective cores; it is not uniform and continuous but shows characteristic timescales of 1-10 s and even subsecond for individual glows. The dynamics of gamma-glowing thunderclouds strongly contradicts the quasi-stationary picture of glows and instead resembles that of a huge gamma-glowing 'boiling pot' in both pattern and behaviour., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Two different hard-radiation phenomena are known to originate from thunderclouds: terrestrial gamma-ray flashes (TGFs) 1 and gamma-ray glows 2 . Both involve an avalanche of electrons accelerated to relativistic energies but are otherwise different. Glows are known to last for one to hundreds of seconds, have moderate intensities and originate from quasi-stationary thundercloud fields 2-5 . TGFs exhibit high intensities and have characteristic durations of tens to hundreds of microseconds 6-9 . TGFs often show a close association with an emission of strong radio signals 10-17 and optical pulses 18-21 , which indicates the 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 the usual multi-pulse TGFs 22-24 but have more pulses and each pulse has a longer duration than ordinary TGFs. FGF durations span from 20 to 250 ms, 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 the atmospheric electricity community for two decades., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Objective: This study aims to evaluate the clinical outcomes of surgical management for placenta accreta spectrum in a Latin American reference hospital specializing in this condition. The evaluation involves a comparison between surgeries performed on an emergent and scheduled basis., Methods: A retrospective cohort study was conducted on patients with placenta accreta spectrum who underwent surgery between January 2011 and November 2021 at a hospital in Colombia, using data from the institutional PAS registry. The study included patients with intraoperative and/or histological confirmation of PAS, regardless of prenatal suspicion. Clinical outcomes were compared between patients who had emergent surgeries and those who had scheduled surgeries. Descriptive analysis involved summary measures and the Shapiro-Wilk test for quantitative variables, with comparisons made using Pearson's Chi-squared test and the Wilcoxon rank sum test, applying a significance level of 5%., Results: A total of 113 patients were included, 84 (74.3%) of them underwent scheduled surgery, and 29 (25.6%) underwent emergency surgery. The emergency surgery group required more transfusions (72.4% vs 48.8%, p=0.047). Patients with intraoperative diagnosis of placenta accreta spectrum (21 women, 19.5%) had a greater volume of blood loss than patients taken into surgery with known presence of placenta accreta spectrum (3500 ml, IQR 1700 - 4000 vs 1700 ml, IQR 1195-2135. p <0.001)., Conclusion: Patients with placenta accreta spectrum undergoing emergency surgery require transfusions more frequently than those undergoing scheduled surgery., Competing Interests: Conflicts to interest: none to declare.

Objective: To evaluate the utility of low-cost simulation models to teach surgical techniques for placenta accreta spectrum (PAS), included in a multimodal education workshop for PAS., Methods: This was an observational, survey-based study. Participants were surveyed before and after the use of low-fidelity mannequins to simulate two surgical techniques for PAS (one-step conservative surgery [OSCS] and modified subtotal hysterectomy [MSTH]), within a multimodal educational workshop. The workshops included pre-course preparation, didactics, simulated practice of the techniques using low-cost models, and viewing live surgery., Results: Six OSCS/MSTH training workshops occurred across six countries and a total of 270 participants were surveyed. The responses of 127 certified obstetricians and gynecologists (OB-GYNs) were analyzed. Participants expressed favorable impressions of all components of the simulated session. Perceived anatomical simulator fidelity, scenario realism, educational component effectiveness, and self-assessed performance improvement received ratings of 4-5 (positive end of the Likert scale) from over 90% of respondents. When asked about simulation's role in technique comprehension, comfort level in technique performance, and likelihood of recommending this workshop to others, more than 75% of participants rated these aspects with a score of 4-5 (positively) on the five-point scale., Conclusion: Low-cost simulation, within a multimodal education strategy, is a well-accepted intervention for teaching surgical techniques for PAS., (© 2024 International Federation of Gynecology and Obstetrics.)

Background: Placenta accreta spectrum is a serious condition associated with significant maternal morbidity and even mortality. The recommended treatment is hysterectomy. An alternative is 1-step conservative surgery, which involves the en bloc resection of the myometrium affected by placenta accreta spectrum along with the placenta, followed by uterine reconstruction. Currently, there are no studies comparing the 2 techniques in the setting of a randomized controlled trial., Objective: We performed a prospectively registered multicenter randomized controlled trial comparing hysterectomy with 1-step conservative surgery. The aim was to collect feasibility and clinical outcomes of the 2 techniques in women assigned to hysterectomy or 1-step conservative surgery. In addition to assessing participants' willingness to be randomized, we also collected data on intraoperative blood loss, transfusion requirement, serious adverse event, and other clinical outcomes., Study Design: Sixty women with strong antenatal suspicion of placenta accreta spectrum were assigned randomly to either hysterectomy (n=31) or 1-step conservative surgery (n=29)., Results: During a 20-month period, 60 of the 64 eligible patients (93.7%) underwent randomization. Intention-to-treat analysis showed that the clinical outcomes for 1-step conservative surgery were comparable to those of hysterectomy (median intraoperative blood loss, 1740 mL [interquartile range, 1010-2410] vs 1500 mL [interquartile range, 1122-2753]; odds ratio, 1 [1-1]; P=.942; median duration of surgery, 135 minutes [interquartile range, 111-180] vs 155 minutes [interquartile range, 120-185]; odds ratio, 0.99 [0.98-1]; P=.151; transfusion rate, 58.6% vs 61.3%; odds ratio, 0.96 [0.83-1.76]; P=.768; and adverse event rate, 17.2% vs 9.7%; odds ratio, 1.77 [0.43-10.19]; P=.398; respectively). In the subgroup of women with type 1 class on topographic classification, all participants allocated to 1-step surgery had successful outcomes, which were superior to those of hysterectomy. This was evidenced by the shorter surgery duration (median, 125 [interquartile range, 98-128] vs 180 [129-226] minutes; P=.002), lower transfusion rates (46.2% vs 82.4%), and fewer units of red blood cells transfused (median, 1 [interquartile range, 1-1.8] vs 3 [interquartile range, 2-4] units; P=.007)., Conclusion: A randomized controlled trial comparing 2 surgical techniques for the treatment of placenta accreta spectrum is feasible. One-step conservative repair is a valid alternative to hysterectomy in the large majority of cases, but this can only be ascertained following intraoperative surgical staging. El resumen está disponible en Español al final del artículo., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: To evaluate the users' opinion on internal manual aortic compression (IMAC) training, using a low-cost simulation model., Methods: An educational strategy was designed to teach IMAC, which included: (1) guided reading of educational material and viewing an explanatory video of IMAC; (2) an introductory lecture with the anatomical considerations, documentation of the cessation of femoral arterial flow during IMAC, and real clinical cases in which this procedure was used; and (3) simulated practice of IMAC with a new low-cost manikin. The educational strategy was applied during three postpartum hemorrhage workshops in three Latin American countries and the opinions of the participants were measured with a survey., Results: Almost all of the participants in the IMAC workshop, including the simulation with the low-cost mannikin, highlighted the usefulness of the strategy (scores of 4/5 and 5/5 on the Likert scale) and would recommend it to colleagues., Conclusion: We present a low-cost simulation model for IMAC as the basis of an educational strategy perceived as very useful by most participants. The execution of this strategy in other populations and its impact on postpartum hemorrhage management should be evaluated in further studies., (© 2023 International Federation of Gynecology and Obstetrics.)

Objective: To describe the knowledge, attitudes, and perceptions of healthcare providers in a region in southwestern Colombia regarding the recommendation and use of long-acting reversible contraceptive (LARC) methods for adolescents., Study Design: This was a cross-sectional study. An online exploratory survey was designed to assess healthcare providers' knowledge, attitudes, and perceptions of Valle del Cauca hospitals. For the development of this the questionnaire, a literature search and validation of the instrument's appearance were conducted., Results: The survey was completed by 115 people. Knowledge: 62.6% and 33% of the participants did not consider themselves capable of correctly placing an intrauterine device (IUD) or a subdermal implant, respectively. However, 73.9% of the participants had adequate theoretical knowledge. Attitudes: 64.3% of the participants considered that adolescents can acquire contraceptive methods without limitations. Short-acting reversible methods were the least recommended. Perceptions: For IUDs, 40.8% and 16.5% of the participants imposed a minimum age and minimum parity requirement for their use, respectively. Side effects were the main reason for not recommending in health institutions with a lower level of complexity., Conclusion: Healthcare providers had positive attitudes and adequate theoretical knowledge concerning to the effectiveness of LARCs. The main areas for improvement were practical knowledge about the insertion and proper use of the devices, indications for referral to gynaecologists for the insertion procedure, and concerns about side effects.

Objectives: To describe the frequency of maternal complications in pregnant women with major or minor placenta previa (PP), and to assess a potential association between PP type and the presence of severe maternal bleeding and other associated outcomes., Materials and Methods: Retrospective descriptive cohort. The study included pregnant women with 20 weeks of gestation or more and a confirmed diagnosis of placenta previa who were seen in a high complexity hospital in Cali (Colombia), between January 2011 and December 2020. Women with a diagnosis of placenta previa and concomitant placenta accreta were excluded. The collected variables were maternal age, body mass index, smoking, obesity, parity, presence of bleeding, postpartum hemorrhage, management of postpartum hemorrhage, transfusion, and maternal ICU admission. A descriptive analysis was performed. The protocol was approved by the ethics committee of Fundaciónn Valle de Lili., Results: A total of 146 patients met the inclusion criteria. The population consisted of women with a mean age of 32 years, with no history of prior surgery, with a prenatal diagnosis of placente previa at week 22; 70 % were major placenta previa cases. The most frequent complications were postpartum hemorrhage (37.9 % vs. 16.3 % for patients with major and minor placenta previa, respectively), transfusion requirement (23.3 and 9.3 %, respectively), and maternal ICU admission (40.8 % vs. 18.6 %, respectively). There were no cases of maternal death., Conclusions: There is a high frequency of complications in women with placenta previa, and it is probably higher in cases of major placenta previa. Further studies are needed to compare the frequency of maternal complications according to the type of placenta previa.

Magnetars are strongly magnetized, isolated neutron stars 1-3 with magnetic fields up to around 10 15  gauss, luminosities of approximately 10 31 -10 36  ergs per second and rotation periods of about 0.3-12.0 s. Very energetic giant flares from galactic magnetars (peak luminosities of 10 44 -10 47  ergs per second, lasting approximately 0.1 s) have been detected in hard X-rays and soft γ-rays 4 , and only one has been detected from outside our galaxy 5 . During such giant flares, quasi-periodic oscillations (QPOs) with low (less than 150 hertz) and high (greater than 500 hertz) frequencies have been observed 6-9 , but their statistical significance has been questioned 10 . High-frequency QPOs have been seen only during the tail phase of the flare 9 . Here we report the observation of two broad QPOs at approximately 2,132 hertz and 4,250 hertz in the main peak of a giant γ-ray flare 11 in the direction of the NGC 253 galaxy 12-17 , disappearing after 3.5 milliseconds. The flare was detected on 15 April 2020 by the Atmosphere-Space Interactions Monitor instrument 18,19 aboard the International Space Station, which was the only instrument that recorded the main burst phase (0.8-3.2 milliseconds) in the full energy range (50 × 10 3 to 40 × 10 6  electronvolts) without suffering from saturation effects such as deadtime and pile-up. Along with sudden spectral variations, these extremely high-frequency oscillations in the burst peak are a crucial component that will aid our understanding of magnetar giant flares., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

In the spring of 2017 an ER-2 aircraft campaign was undertaken over continental United States to observe energetic radiation from thunderstorms and lightning. The payload consisted of a suite of instruments designed to detect optical signals, electric fields, and gamma rays from lightning. Starting from Georgia, USA, 16 flights were performed, for a total of about 70 flight hours at a cruise altitude of 20 km. Of these, 45 flight hours were over thunderstorm regions. An analysis of two gamma ray glow events that were observed over Colorado at 21:47 UT on 8 May 2017 is presented. We explore the charge structure of the cloud system, as well as possible mechanisms that can produce the gamma ray glows. The thundercloud system we passed during the gamma ray glow observation had strong convection in the core of the cloud system. Electric field measurements combined with radar and radio measurements suggest an inverted charge structure, with an upper negative charge layer and a lower positive charge layer. Based on modeling results, we were not able to unambiguously determine the production mechanism. Possible mechanisms are either an enhancement of cosmic background locally (above or below 20 km) by an electric field below the local threshold or an enhancement of the cosmic background inside the cloud but then with normal polarity and an electric field well above the Relativistic Runaway Electron Avalanche threshold., (©2019. The Authors.)

We report a 511-keV photon flux enhancement that was observed inside a thundercloud and is a result of positron annihilation. The observation was made with the In-flight Lightning Damage Assessment System (ILDAS) on board of an A340 test aircraft. The aircraft was intentionally flying through a thunderstorm at 12-km altitude over Northern Australia in January 2016. Two gamma ray detectors showed a significant count rate increase synchronously with fast electromagnetic field variations registered by an on-board antenna. A sequence of 10 gamma ray enhancements was detected, each lasted for about 1 s. Their spectrum mainly consists of 511-keV photons and their Compton component. The local electric activity during the emission was identified as a series of static discharges of the aircraft. A full-scale Geant4 model of the aircraft was created to estimate the emission area. Monte Carlo simulation indicated that the positrons annihilated in direct vicinity or in the aircraft body.