Global Distribution of Key Features of Streamer Corona Discharges in Thunderclouds

We present nighttime worldwide distributions of key features of Blue LUminous Events (BLUEs) detected by the Modular Multispectral Imaging Array of the Atmosphere-Space Interaction Monitor. Around 10% of all detected BLUEs exhibit an impulsive single pulse shape. The rest of BLUEs are unclear (impulsive or not) single, multiple or with ambiguous pulse shapes. BLUEs exhibit two distinct populations with peak power density <25 µWm^-2 (common) and ≥25 µWm^-2 (rare) with different rise times and durations. The altitude (and depth below cloud tops) zonal distribution of impulsive single pulse BLUEs indicate that they are commonly present between cloud tops and a depth of ≤4 km in the tropics and ≤1 km in mid and higher latitudes. Impulsive single pulse BLUEs in the tropics are the longest (up to ∼4 km height) and have the largest number of streamers (up to ∼3 × 10⁹). Additionally, the analysis of BLUEs has turned out to be particularly complex due to the abundance of radiation belt particles (at high latitudes and in the South Atlantic Anomaly [SAA]) and cosmic rays all over the planet. True BLUEs can not be fully distinguished from radiation belt particles and cosmic rays unless other ground-based measurements associated with the optically detected BLUEs are available. Thus, the search algorithm of BLUEs presented in Soler et al. (2021), https://doi.org/10.1029/2021gl094657 is now completed with a new additional step that, if used, can considerably smooth the SAA shadow but can also underestimate the number of BLUEs worldwide.

Submicrosecond Spectroscopy of Lightning-Like Discharges: Exploring New Time Regimes

Submicrosecond (0.476 μs per frame with an exposure time of 160 ns) high-resolution (0.38 nm) time-resolved spectra of laboratory-produced lightning-like electrical discharges have been recorded for the first time within the visible spectral range (645-665 nm). The spectra were recorded with the GrAnada LIghtning Ultrafast Spectrograph (GALIUS), a high-speed imaging spectrograph recently developed for lightning research in the IAA-CSIC. Unprecedented spectral time dynamics are explored for meter long laboratory electrical discharges produced with a 2.0 MV Marx generator. The maximum electron density and gas temperature measured in a timescale of ≤0.50 μs (160 ns) were, respectively, ≃1018 cm-3 and ≃32,000 K. Overpressure in the lightning-like plasma channel, black-body dynamics, and self-absorption in spectral lines were investigated.

Influence of Elastic Scattering on Electron Swarm Distribution in Electrified Gases

The propagation of energetic electrons through air is one key component in the generation of high-energy atmospheric phenomena such as lightning-generated X-ray bursts, terrestrial gamma ray flashes (TGFs), and gamma ray glows. We show here that models for this propagation can be considerably affected by the parameterization of the differential cross section of elastic scattering of electrons on the molecular components of air. We assess existing parameterizations and propose a more accurate one that builds upon the most up-to-date measurements. Then we conclude that by overweighting the forward scattering probability, previous works may have overestimated the production of runaway electrons under high electric fields close to the thermal runaway threshold.

On the Emergence Mechanism of Carrot Sprites

We investigate the launch of negative upward streamers from sprite glows. This phenomenon is readily observed in high-speed observations of sprites and underlies the classification of sprites into carrot or column types. First, we describe how an attachment instability leads to a sharply defined region in the upper part of the streamer channel. This region has an enhanced electric field, low conductivity and strongly emits in the first positive system of molecular nitrogen. We identify it as the sprite glow. We then show how, in the most common configuration of a carrot sprite, several upward streamers emerge close to the lower boundary of the glow, where negative charge gets trapped and the lateral electric field is high enough. These streamers cut off the current flowing toward the glow and lead to the optical deactivation of the glow above. Finally, we discuss how our results naturally explain angel sprites.

Analysis of the Spatial Nonuniformity of the Electric Field in Spectroscopic Diagnostic Methods of Atmospheric Electricity Phenomena

The spatial nonuniformity of the electric field in air discharges, such as streamers, can influence the accuracy of spectroscopic diagnostic methods and hence the estimation of the peak electric field. In this work, we use a self-consistent streamer discharge model to investigate the spatial nonuniformity in streamer heads and streamer glows. We focus our analysis on air discharges at atmospheric pressure and at the low pressure of the mesosphere. This approach is useful to investigate the spatial nonuniformity of laboratory discharges as well as sprite streamers and blue jet streamers, two types of transient luminous events taking place above thunderclouds. This characterization of the spatial nonuniformity of the electric field in air discharges allows us to develop two different spectroscopic diagnostic methods to estimate the peak electric field in cold plasmas. The commonly employed method to derive the peak electric field in streamer heads underestimates the electric field by about 40-50% as a consequence of the high spatial nonuniformity of the electric field. Our diagnostic methods reduce this underestimation to about 10-20%. However, our methods are less accurate than previous methods for streamer glows, where the electric field is uniformly distributed in space. Finally, we apply our diagnostic methods to the measured optical signals in the second positive system of N2 and the first negative system ofN 2 + of sprites recorded by Armstrong et al. (1998, https://doi.org/10.1016/S1364-6826(98)00026-1) during the SPRITE's 1995 and 1996 campaigns.

P5753Jailed pressure wire to assess the side branch result for bifurcation lesions treated by provisional stenting strategy: iFR as a new index

Purpose

To analyze the feasibility and efficacy of the jailed pressure wire technique for bifurcation lesions treated by provisional stenting strategy and to assess the physiological side branch (SB) result using instantaneous wave free ratio (iFR).

Methods

Between June 2017 and December 2018, 50 patients who presented a bifurcation lesion considered appropriate for provisional stenting strategy were included in the study. Pressure wire was passed to side branch before treatment. Main vessel (MV) and side branch (SB) was predilated at the operator criteria. iFR determination was obtained in the SB baseline and after MV stenting (leaving the pressure wire jailed). Afterwards, the wire was removed to MV ostium to discard the possibility of drift. SB postdilation was performed if SB iFR was less than 0,89 (according to vessel thresholds established in clinical trials), evaluating the result by a new iFR determination.

Results

The mean age was 64±10 years. Sixteen patients (32%) had diabetes. Clinical presentation was stable angina in 26 patients (52%), non-STEMI in 19 patients (38%) and STEMI (non culprit lesion) in 5 patients (10%). The most frequent bifurcation type according to Medina classifications was 1,1,0 (21 patients, 42%). Seventeen patients (34%) had a true bifurcation lesion. The MV and SB reference diameter was 3,0±0,5 mm and 2,25±0,5 mm respectively. Most of the bifurcations were located at the left anterior descending artery/diagonal branch (27 bifurcations, 54%). Ten patients (20%) presented a distal left main bifurcation. Baseline SB iFR was 0,78±0,2. Under continuous SB iFR monitoring MV stenting was performed by trapping the pressure wire. After MV stenting, the SB iFR changed to 0,90±0,1. We confirmed the presence of drift in 5 patients (10%). In these cases, recalibration of the wire and SB rewiring was performed in 4 cases. In the remaining patient, rewiring was not possible even using specific coronary wires.

According to SB IFR, postdilation was necessary in 14 patients (28%). Final SB iFR was 0,94±0,03. A second stent was not necessary in any patient because final SB iFR was higher than 0.89 in all cases. We observed discordance between angiographic and physiological result in 17 cases (34%). All the wires could be removed. Forty wires (80%) were microscopically analyzed. Some grade of microscopic damage was found in 32 wires (80%), all of them distal to the pressure sensor. However, only one of these wires (2%) presented severe damage, and no case of fracture was observed.

After a mean follow up time of 10±6 months only one patient (2%) presented a major cardiac adverse event (acute coronary syndrome due to voluntary cessation of dual antiplatelet therapy).

Conclusions

The use of jailed pressure wire to monitor SB results for bifurcations treated by provisional stenting seems to be safe. The iFR index seems to provide new physiological information about the significance of the SB stenosis.

Spontaneous Emergence of Space Stems Ahead of Negative Leaders in Lightning and Long Sparks

We investigate the emergence of space stems ahead of negative leaders. These are luminous spots that appear ahead of an advancing leader mediating the leader's stepped propagation. We show that space stems start as regions of locally depleted conductivity that form in the streamers of the corona around the leader. An attachment instability enhances the electric field leading to strongly inhomogeneous, bright, and locally warmer regions ahead of the leader that explain the existing observations. Since the attachment instability is only triggered by fields above 10 kV/cm and internal electric fields are lower in positive than in negative streamers, our results explain why, although common in negative leaders, space stems, and stepping are hardly observed if not absent in positive leaders. Further work is required to fully explain the streamer to leader transition, which requires an electric current persisting for timescales longer than the typical attachment time of electrons, around 100 ns.

Use of Peritoneovenous Shunt for the Management of Refractory Ascites

BACKGROUND

Guidelines for the management of refractory ascites (RA) recommend transjugular intrahepatic portosystemic shunting (TIPS), diuretics, and paracentesis as the main strategies, discouraging use of surgical peritoneovenous shunts (PVSs). However, PVSs, including both Denver (DS) or saphenoperitoneal (SPS) modalities, may still have indications. Herein we report our experience with PVSs in the context of modern surgical and anesthetic management.

METHODS

In our unit, PVSs are offered to patients with ascites refractory to diuretics in which TIPS are contraindicated. Heart function and spontaneous bacterial peritonitis must be assessed before surgical indication.

RESULTS

Seven procedures were performed on 5 patients (6-DS, 1-SPS) in 2013. Their mean age was 61 (range, 54-68) years. In 3 patients, the indication was RA without options for liver transplant; 2 patients were on the waiting list for liver transplantation, which were performed to improve renal function and quality of life (QOL). The median hospital stay was 6.5 (range, 3-12) days. All patients were alive after 12 months. One patient died 2 years after the first DS and another later died due to liver insufficiency with patency of the DS. The ascites was well-controlled in 4 of 5 patients at up to 48 months of follow-up. Decreases in diuretics doses, proper weight maintenance, and a dramatic improvement in QOL (measured by a modified Ascites Symptom Inventory-7 [ASI-7] test) were observed after the procedures.

CONCLUSION

PVSs are useful for the treatment of patients with RA who develop resistance to common therapies, leading to a major improvement in QOL. These surgical procedures should be included in the armamentarium of experienced liver surgeons.

Optimizing the management of patients with BCLC stage-B hepatocellular carcinoma: Modern surgical resection as a feasible alternative to transarterial chemoemolization

OBJECTIVE

To analyse the impact of liver resection (LR) in patients with Hepatocellular Carcinoma (HCC) within the Barcelona-Clinic-Liver-Cancer (BCLC)-B stage.

METHODS

Analysis of patients with BCLC-B HCC treated with LR or transarterial chemoembolization (TACE) between 2007 and 2012 in our hospital. Survival/recurrence analyses were performed by log-rank tests and Cox multivariate models. Further analyses were specifically obtained for the HCC subclassification (B1-2-3-4) proposed recently.

RESULTS

Eighty patients were treated (44-TACE/36-LR). Number of nodules was [1.8(1.1)], being multinodular in 50% of cases. Although resected patients had a higher hospital stay than those who underwent TACE (14 ± 13 vs 7 ± 6; P = 0.004), the rate and severity of complications was lower measured by Dindo-Clavien scale (P < 0.05). Overall survival was 40% with a median follow-up of 29.5 months (0.07-96.9). Five-years survival rates were 62.9%, 28.1% and 15.4%, respectively (P = 0.004) for B1, B2 and B3-4 stages. Cox model showed that only total bilirubin [OR = 2.055(1.23-3.44)] and BCLC subclassification B3-4 [OR = 2.439(1.04-5.7)] and B2 [OR = 2.79(1.35-5.77)] vs B1 were independent predictors of 5-years-survival. In B1 patients, surgical approach led a significant decrease in 5-years recurrence-rate (25% vs 60%; P = 0.018). In the surgical subgroup analysis, better results were observed if well/moderate differentiation combined with no microvascular-invasion (VI) in 5-years-survival (84.6%; P = 0.001) and -recurrence (23.1%; P = 0.041), respectively. These survival and recurrence trends were remarkable in B1 stages.

CONCLUSIONS

Management of Intermediate BCLC-B HCC stage should be more complex and include updated criteria regarding B-stage subclassifications, VI and tumour differentiation. Modern surgical resection would offer improved survival benefit with acceptable safety in selected BCLC-B stage patients.

Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base–emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers that are required to match the limiting efficiency of dual-junction solar cells without using tunnel junctions. The device naturally emerges as a three-terminal solar cell and can also be used as building block of multijunction solar cells with an increased number of junctions.

Multiple junction solar cells offer the means to high-efficiency photovoltaics but suffer from complicated manufacturing and packing. Here Martí et al., propose a three-terminal heterojuntion bipolar transistor solar cell that simplifies the structure reducing the number of layers while maintaining the efficiency.

Intermediate band solar cell with extreme broadband spectrum quantum efficiency

We report, for the first time, about an intermediate band solar cell implemented with InAs/AlGaAs quantum dots whose photoresponse expands from 250 to ∼6000  nm. To our knowledge, this is the broadest quantum efficiency reported to date for a solar cell and demonstrates that the intermediate band solar cell is capable of producing photocurrent when illuminated with photons whose energy equals the energy of the lowest band gap. We show experimental evidence indicating that this result is in agreement with the theory of the intermediate band solar cell, according to which the generation recombination between the intermediate band and the valence band makes this photocurrent detectable.

Relativistic runaway ionization fronts

We investigate the first example of self-consistent impact ionization fronts propagating at relativistic speeds and involving interacting, high-energy electrons. These fronts, which we name relativistic runaway ionization fronts, show remarkable features such as a bulk speed within less than one percent of the speed of light and the stochastic selection of high-energy electrons for further acceleration, which leads to a power-law distribution of particle energies. A simplified model explains this selection in terms of the overrun of Coulomb-scattered electrons. Appearing as the electromagnetic interaction between electrons saturates the exponential growth of a relativistic runaway electron avalanche, relativistic runaway ionization fronts may occur in conjunction with terrestrial gamma-ray flashes and thus explain recent observations of long, power-law tails in the terrestrial gamma-ray flash energy spectrum.

Molecular characterization of three novel chemokine receptors in rainbow trout (Oncorhynchus mykiss)

Chemokines signal through a family of seven-transmembrane domain G-coupled receptors in order to regulate both leukocyte mobilization and activate the recruited cells. Although many chemokines have been identified in rainbow trout (Oncorhynchus mykiss), only a few chemokine receptors have been reported to date. In this work, we have cloned three novel chemokine receptors in rainbow trout. One of these receptors seems to be a clear orthologue of CCR6, while the second one constitutes a novel CCR9 gene different from the previous CCR9 reported in this species. This gene, which we have designated as CCR9B, represents another lineage of fish CCR9 genes, not previously identified. Finally, a deeper phylogenetic analysis of the third novel chemokine receptor gene, which had been identified on the basis of sequence similarity to CCR3, constitutes a novel lineage of CCR receptors which has no equivalent in humans and that may be teleost-specific. We have designated this novel gene as CCR13, to avoid any possible ascription to mammalian genes. Further transcriptional studies revealed that CCR6 was constitutively transcribed in thymus, gills, hindgut and peripheral blood leukocytes (PBLs), while CCR9B was strongly transcribed in thymus and PBLs but also in spleen, gills, hindgut and brain at lower levels. CCR13, on the other hand, was strongly detected in spleen, head kidney and PBLs and faintly in thymus, gills, brain and gonad. The data provided constitutes a step forward the identification of novel chemokine receptors that may contribute to a future understanding of chemokine signalling in fish.

Critical role of the death receptor pathway in the antitumoral effects induced by hispanolone derivatives

Labdane diterpenoids have a broad spectrum of biological activities including antibacterial, antiviral and anti-inflammatory properties. However, little is known about their possible role in the apoptotic cell death machinery. Here, we report that hispanolone derivatives, a group of labdane diterpenoids, induce apoptosis in different tumor cell lines by activating caspase-8 with subsequent participation of mitochondrial signaling. Activation of caspase-8 by hispanolone derivatives was followed by a decrease in mitochondrial membrane potential, the release of apoptotic factors from mitochondria to the cytosol, and activation of caspases-9 and 3. Hispanolone derivatives also led to a time-dependent cleavage of Bid. Inhibition of caspase-8 abrogated these processes, suggesting that the death receptor pathway has a critical role in the apoptotic events induced by hispanolone derivatives. In addition, silencing death receptors with small interfering RNA s or pretreating cells with neutralizing antibodies to Fas ligand, tumor necrosis factor receptor 1 (TNF-R1), and TNF-α receptor 2 (TRAIL) inhibited diterpenoid-induced apoptosis, revealing it to be dependent on these death receptors. Interestingly, hispanolone derivatives had no effect on non-tumor cells. Consistently, in vivo bioluminescence imaging corroborates this antineoplasic effect, as hispanolone derivatives significantly decrease cancer growth in tumor xenograft assays. These data demostrate the antitumoral effects of hispanolone derivatives and provide relevant preclinical validation for the use of these compounds as potent therapeutic agents in cancer treatment.