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Abstract Coronae, which are weak electrical discharges, have long been hypothesized to form on trees under thunderstorms, though never directly observed, characterized, or quantified. Using a newly developed instrument that measures ultraviolet emissions from coronae, the first direct observations and quantifications of coronae are presented for two trees under a thunderstorm in North Carolina. Coronae moved sporadically among leaves on every tree branch in a narrow field of view while the thunderstorm was directly overhead. Coronae emitted ∼10¹¹photons at 260 nm, corresponding to electrical currents of ∼1 μA, derived from unique measurements relating corona intensity to tree electrical current. Similar results across four additional storm intercepts from Florida to Pennsylvania give rise to a vision of swaths of scintillating corona glow as thunderstorms pass over forests. Such widespread coronae have implications for the removal of hydrocarbons emitted by trees, subtle tree leaf damage, and limited thunderstorm electrification. 

The atmosphere’s most important oxidizer, the hydroxyl radical (OH), is generated in abundance by lightning, but the contribution of this electrically generated OH (LOH) to global OH oxidation remains highly uncertain. Part of this uncertainty is due to the abundant nitric oxide (NO) also generated in lightning, which could rapidly remove the LOH before it can oxidize other pollutants in the atmosphere. However, evidence from a previous laboratory study indicated LOH is not immediately consumed by NO, possibly because LOH’s production is spatially separated from the NO production in lightning flashes. This hypothesis of spatially separate OH and NO production is further tested here in a series of laboratory experiments, where the OH decays were measured from spark discharges in air which had increasing amounts of NO added to it. The LOH decayed faster as more NO was added to the air, indicating that the LOH was reacting with the added NO, and not the spark NO. Thus, LOH from lightning flashes is not immediately consumed by the electrically generated NO but is available to oxidize other pollutants in the atmosphere and contribute to global OH oxidation. Subsequent modelling of the laboratory data also supports the spatially separate production of LOH and NO, and further suggests that substantial HONO is also produced by sparks and lightning in the atmosphere. 

Abstract Recently, electrical discharges have been identified as a potentially significant source of the atmosphere's most important oxidant, the hydroxyl radical. Measurements of hydroxyl, the closely related hydroperoxyl radical, and the nitrogen oxides from sparks and subvisible discharges were made in the laboratory under different environmental and electrical conditions representing those found in the troposphere. However, there were still several conditions not yet investigated that could impact hydroxyl and hydroperoxyl production in electrical discharges. In this study, the production of electrically generated hydroxyl and hydroperoxyl (LHO_x) and nitrogen oxides (LNO_x) was measured under three new conditions not tested previously, including lower pressure, different temperatures, and the presence of cloud droplet‐sized water droplets. In spark discharges, LHO_xwas mostly independent of pressure, increased with increasing temperature, and was unaffected by the water droplets. LNO_xgeneration was independent of temperature from −10 to 40°C and the presence of water droplets, but increased 1.5‐fold with decreasing pressure. LNO_xgeneration was also found to be sensitive to changes in spark intensity and air flow in the laboratory setup. Increasing temperature also made it more likely that a discharge was visible instead of subvisible, but did not impact LHO_xproduction in subvisible discharges. Even under these new conditions, the laboratory results agree with results of LHO_xfrom a field campaign, demonstrating the relevance of the laboratory experiments to the atmosphere. 

Characterizing exoplanets’ spectra is a crucial step in understanding the chemical and physical processes shaping their atmospheres and constraining their formation and evolutionary history. The X-SHYNE library is a homogeneous sample of 43 medium-resolution (R_λ~ 8000) infrared (0.3–2.5 μm) spectra of young (<500 Myr), low-mass (<20 M_Jup), and cold (T_eff~600–2000 K) isolated brown dwarfs and wide-separation companions observed with the VLT/X-Shooter instrument. To characterize our targets, we performed a global comparative analysis. We first applied a semiempirical approach. By refining their age and bolometric luminosity, we derived key atmospheric and physical properties, such as T_eff, mass, surface gravity (g), and radius, using the evolutionary modelCOND03. These results were then compared with the results from a synthetic analysis based on three self-consistent atmospheric models: the cloudy modelsExo-REMandSonora Diamondback, and the cloudless modelATMO. To compare our spectra with these grids we used the Bayesian inference codeForMoSA. We found similar L_bolestimates between both approaches, but an underestimated T_efffrom the cloudy models, likely due to a lack of absorbers that could dominate the J and H bands of early L. We also observed a discrepancy in the log(g) estimates, which are dispersed between 3.5 and 5.5 dex for mid-L objects. We interpret this as a bias caused by a range of rotational velocities leading to cloud migration toward equatorial latitudes, combined with a variety of viewing angles that result in different observed atmospheric properties (cloud column densities, atmospheric pressures, etc.). This interpretation is supported by the correlation of the color anomaly Δ(J–K) of each object with log(g) and the parameter f_sedthat drives the sedimentation of the clouds. Finally, while providing robust estimates of [M/H] and C/O for individual objects remains challenging, the X-SHYNE library globally suggests solar values that are consistent with a formation via stellar formation mechanisms. This study highlights the strength of homogeneous datasets in performing comparative analyses, reducing the impact of systematics, and ensuring robust conclusions while avoiding overinterpretation. 

This special issue examines innovative methods in three areas of protest studies: (1) survey methodology and scaling, (2) the development and assessment of political event data, and (3) methods of contextual analysis. The articles provide new techniques and general methodologies for improving the quality of data that we have about protest, especially in the comparative study of protest. 

Public opinion surveys constitute a widespread, powerful tool to study peoples’ attitudes and behaviors from comparative perspectives. However, even global surveys can have limited geographic and temporal coverage, which can hinder the production of comprehensive knowledge. To expand the scope of comparison, social scientists turn to ex-post harmonization of variables from datasets that cover similar topics but in different populations and/or at different times. These harmonized datasets can be analyzed as a single source and accessed through various data portals. However, the Survey Data Recycling (SDR) research project has identified three challenges faced by social scientists when using data portals: the lack of capability to explore data in-depth or query data based on customized needs, the difficulty in efficiently identifying related data for studies, and the incapability to evaluate theoretical models using sliced data. To address these issues, the SDR research project has developed the SDR Querier, which is applied to the harmonized SDR database. The SDR Querier includes a BERT-based model that allows for customized data queries through research questions or keywords (Query-by-Question), a visual design that helps users determine the availability of harmonized data for a given research question (Query-by-Condition), and the ability to reveal the underlying relational patterns among substantive and methodological variables in the database (Query-by-Relation), aiding in the rigorous evaluation or improvement of regression models. Case studies with multiple social scientists have demonstrated the usefulness and effectiveness of the SDR Querier in addressing daily challenges. 

A common claim about the affluent democracies is that protest is trending, becoming more legitimate and widely used by all political contenders. In the new democracies, protest is seen as having contributed to democratization, but growing apathy has led to protest decline while in authoritarian regimes protest may be spurring more democratization. Assessing these ideas requires comparative trend data covering 15 or more years but constructing such data confronts problems. The major problem is that the most available survey item asks “have you ever joined (lawful) demonstrations,” making it difficult to time when this protest behavior occurred. We advance a novel method for timing these “ever” responses by focusing on young adults (aged 18-23 years), who are likely reporting on participation within the past 5 years. Drawing on the Survey Data Recycling harmonized data set, we use a multilevel model including harmonization and survey quality controls to create predicted probabilities for young adult participation (576 surveys, 119 countries, 1966-2010). Aggregating these to create country-year rate estimates, these compare favorably with overlapping estimates from surveys asking about “the past 5 years or so” and event data from the PolDem project. Harmonization and survey quality controls improve these predicted values. These data provide 15+ years trend estimates for 60 countries, which we use to illustrate the possibilities of estimating comparative protest trends.