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​​​​​​​The 21 June 2019 Raikoke eruption (48° N, 153° E) generated one of the largest amounts of sulfur emission to the stratosphere since the 1991 Mt. Pinatubo eruption. Satellite measurements indicate a consensus best estimate of 1.5 Tg for the sulfur dioxide (SO 2) injected at an altitude of around 14–15 km. The peak Northern Hemisphere (NH) mean 525 nm stratospheric aerosol optical depth (SAOD) increased to 0.025, a factor of 3 higher than background levels. The Volcano Response (VolRes) initiative provided a platform for the community to share information about this eruption which significantly enhanced coordination efforts in the days after the eruption. A multi-platform satellite observation subgroup formed to prepare an initial report to present eruption parameters including SO 2 emissions and their vertical distribution for the modeling community. It allowed us to make the first estimate of what would be the peak in SAOD 1 week after the eruption using a simple volcanic aerosol model. In this retrospective analysis, we show that revised volcanic SO 2 injection profiles yield a higher peak injection of the SO 2 mass. This highlights difficulties in accurately representing the vertical distribution for moderate SO 2 explosive eruptions in the lowermost stratosphere due to limited vertical sensitivity of the current satellite sensors (± 2 km accuracy) and low horizontal resolution of lidar observations. We also show that the SO 2 lifetime initially assumed in the simple aerosol model was overestimated by 66 %, pointing to challenges for simple models to capture how the life cycle of volcanic gases and aerosols depends on the SO 2 injection magnitude, latitude, and height. Using a revised injection profile, modeling results indicate a peak NH monthly mean SAOD at 525 nm of 0.024, in excellent agreement with observations, associated with a global monthly mean radiative forcing of - 0.17 W m -2 resulting in an annual global mean surface temperature anomaly of - 0.028 K. Given the relatively small magnitude of the forcing, it is unlikely that the surface response can be dissociated from surface temperature variability. [ABSTRACT FROM AUTHOR]

A growing number of general circulation models are adapting interactive sulfur and aerosol schemes to improve the representation of relevant physical and chemical processes and associated feedbacks. They are motivated by investigations of climate response to major volcanic eruptions and potential solar geoengineering scenarios. However, uncertainties in these schemes are not well constrained. Stratospheric sulfate is modulated by emissions of sulfur-containing species of anthropogenic and natural origin, including volcanic activity. While the effects of volcanic eruptions have been studied in the framework of global model intercomparisons, the background conditions of the sulfur cycle have not been addressed in such a way. Here, we fill this gap by analyzing the distribution of the main sulfur species in nine global atmospheric aerosol models for a volcanically quiescent period. We use observational data to evaluate model results. Overall, models agree that the three dominant sulfur species in terms of burdens (sulfate aerosol, OCS, and SO 2) make up about 98 % stratospheric sulfur and 95 % tropospheric sulfur. However, models vary considerably in the partitioning between these species. Models agree that anthropogenic emission of SO 2 strongly affects the sulfate aerosol burden in the northern hemispheric troposphere, while its importance is very uncertain in other regions, where emissions are much lower. Sulfate aerosol is the main deposited species in all models, but the values deviate by a factor of 2. Additionally, the partitioning between wet and dry deposition fluxes is highly model dependent. Inter-model variability in the sulfur species is low in the tropics and increases towards the poles. Differences are largest in the dynamically active northern hemispheric extratropical region and could be attributed to the representation of the stratospheric circulation. The differences in the atmospheric sulfur budget among the models arise from the representation of both chemical and dynamical processes, whose interplay complicates the bias attribution. Several problematic points identified for individual models are related to the specifics of the chemistry schemes, model resolution, and representation of cross-tropopause transport in the extratropics. Further model intercomparison research is needed with a focus on the clarification of the reasons for biases, given the importance of this topic for the stratospheric aerosol injection studies. [ABSTRACT FROM AUTHOR]

In higher plants, sexual reproduction is characterized by meiosis of the first cells of the germlines, and double fertilization of the egg and central cell after gametogenesis. In contrast, in apomicts of the genus Boechera , meiosis is omitted or altered and only the central cell requires fertilization, while the embryo forms parthenogenetically from the egg cell. To deepen the understanding of the transcriptional basis underlying these differences, we applied RNA-seq to compare expression in reproductive tissues of different Boechera accessions. This confirmed previous evidence of an enrichment of RNA helicases in plant germlines. Furthermore, few RNA helicases were differentially expressed in female reproductive ovule tissues harboring mature gametophytes from apomictic and sexual accessions. For some of these genes, we further found evidence for a complex recent evolutionary history. This included a homolog of Arabidopsis thaliana FASCIATED STEM4 (FAS4). In contrast to AtFAS4 , which is a single-copy gene, FAS4 is represented by three homologs in Boechera , suggesting a potential for subfunctionalization to modulate reproductive development. To gain first insights into functional roles of FAS4 , we studied Arabidopsis lines carrying mutant alleles. This identified the crucial importance of AtFAS4 for reproduction, as we observed developmental defects and arrest during male and female gametogenesis. [ABSTRACT FROM AUTHOR]

Aerosols play an important role in the Earth system, but their impact on cloud properties and the resulting radiative forcing of climate remains highly uncertain. The large temporal and spatial variability of a number of aerosols properties and the choice of different 'pre-industrial' reference years prevent a concise understanding of basic underlying patterns and trends in aerosols and their impacts on clouds and radiation. In this study, we characterize the spatial patterns and long-term evolution of lower tropospheric aerosols (in terms of regimes) by clustering multiple aerosol properties from preindustrial times to the year 2050 under three different Shared Socioeconomic Pathway (SSP) scenarios, based on a combination of global aerosol model simulations and statistic-based machine learning algorithms. Our analysis suggests that in comparison with the present-day case, lower tropospheric aerosol regimes during preindustrial times are mostly represented by regimes of comparatively clean conditions whereby marked differences between the years 1750 and 1850 emerge due to the growing influence of agriculture and other anthropogenic activities in 1850. Key aspects of the spatial distribution and extent of the aerosol regimes identified in year 2050 differ compared to pre-industrial and present-day, with significant variations resulting from the emission scenario investigated. In 2050, the low emission SSP1-1.9 scenario is the only scenario where the spatial distribution and extent of the aerosol regimes very closely resembles preindustrial conditions whereby the similarity is greater compared to 1850 than 1750. The aerosol regimes for 2050 under SSP3-7.0 closely resemble present-day conditions, but there are some notable regional differences: developed countries tend to shift towards cleaner conditions in future, while the opposite is the case for developing countries. The aerosol regimes for 2050 under SSP2-4.5 represent an intermediate stage between preindustrial times and present-day. Further analysis indicates a north/south difference in the background regime during preindustrial times, and close resemblance of pre-industrial aerosol conditions in the marine regime to present-day conditions in the Southern Hemispheric ocean. Overall, our study allows to extract a clear and condensed picture of the spatial extent and distribution of aerosols for different time periods and emission scenarios and to summarize these in terms of aerosol regimes. The approach and findings of this study can be used for designing targeted measurements of different preindustrial-like conditions, and for tailored air pollution mitigation measures in specific regions. [ABSTRACT FROM AUTHOR]

The Mt Samalas eruption, thought to have occurred in summer 1257, ranks as one of the most explosive sulfur-rich eruptions of the Common Era. Despite recent convergence, several dates have been proposed for the eruption ranging between 1256–1258, with, as of yet, no single combination of evidence that has been able to robustly distinguish between and exclude the other dates proposed for the Mt Samalas eruption. Widespread surface cooling and hydroclimate perturbations following the eruption have been invoked as contributing to a host of 13th century social and economic crises, although regional-scale variability in the post-eruption climate response remains uncertain. In this study we run ensemble simulations using the UK Earth System Model (UKESM1) with a range of eruption scenarios and initial conditions in order to compare our simulations with the most complete globally resolved multi-proxy database for the Mt Samalas eruption to date, incorporating tree rings, ice cores, and historical records. This allows more precise constraints to be placed on the year and season of the Mt Samalas eruption, as well as an investigation into the regionally heterogeneous post-eruption climate response. Using a multi-proxy to model comparison, we are able to robustly distinguish between July 1257 and January 1258 eruption scenarios, where the July 1257 ensemble simulation achieves considerably better agreement with spatially averaged and regionally resolved proxy surface temperature reconstructions. These reconstructions suggest the onset of significant cooling across Asia and Europe in 1258 and thus support the plausibility of previously inferred historical connections. Model-simulated temperature anomalies also point to severe surface cooling across the Southern Hemisphere with as of yet unexplored historical implications for impacted civilisations. Model simulations of polar sulfate deposition also reveal distinct differences in the timing of ice sheet deposition between the two simulated eruption dates, although comparison of the magnitude or asymmetric deposition of sulfate aerosol remains limited by large inter-model differences and complex intra-model dependencies. Overall, the multi-proxy to model comparison employed in this study has strong potential in constraining similar uncertainties in eruption source parameters for other historical eruptions for which sufficient coincident proxy records are available, although care is needed to avoid the pitfalls of model–multi-proxy comparison. [ABSTRACT FROM AUTHOR]

Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.

The COVID-19 pandemic has brought unprecedented challenges to researchers worldwide, and extensive studies have demonstrated that its impacts since March 2020 have been unequal, including across research discipline, gender, and career status. In 2023, as we navigate the post-pandemic times, questions persist regarding potential disparities and enduring effects faced by volcanology researchers, whose activities range from field work in remote areas to laboratory experiments and numerical modelling. In this study, we explore the multifaceted impacts of the pandemic on volcanology researchers through an online survey distributed globally from January to March 2023. Our survey findings reveal that a considerable fraction of volcanology researchers (44%-62%) face longer-term challenges from the pandemic that continue to impact their research, with a notably higher proportion among early career researchers (62%) and researchers with disabilities (76%). In addition, over half (52%) of all surveyed researchers indicated that they had left or considered leaving academia due to pandemic-related factors. A significantly higher proportion of disabled researchers (56%-70%) had left or considered leaving academia compared to researchers without disabilities (42%). Our findings underscore the pandemic's long-lasting and disproportionate impacts on early career and disabled volcanology researchers. We emphasis the need for concerted efforts by research organisations and funding bodies to mitigate the pandemic's enduring impacts, and stress the importance of making conferences accessible to support disabled researchers' participation. As the pandemic's long-lasting impacts ripple across the broader scientific community, the insights from this research can be used for fostering equitable practices and shaping policies beyond volcanology to other research disciplines. [ABSTRACT FROM AUTHOR]

Background: Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in several tissues and organs causing, among others, severe eye symptoms. The high instability of cysteamine eye drops makes it difficult to develop formulations with an acceptable shelf life to be prepared in hospital pharmacy departments. Previously, a new compounded formulation of cysteamine eye drops in hyaluronic acid (HA) packaged in innovative single-dose systems was developed. Methods: Long-term stability at −20 °C of this formulation was studied considering the content of cysteamine, pH, osmolality, viscosity, and microbiological analysis. The oxygen permeability of single-dose containers was also studied and an ocular biopermanence study was conducted in healthy volunteers measuring lacrimal stability and volume parameters. Results: Data confirm that cysteamine concentration remained above 90% for 120 days, all parameters remaining within the accepted range for ophthalmic formulations. The permeability of the containers was reduced over time, while ocular biopermanence was maintained despite the freezing process and storage time. Conclusions: 0.55% cysteamine hydrochloride formulation in HA and packaged in single-dose containers preserved at −20 °C is stable for 120 days protected from light, presenting high potential for its translation into clinical practice when commercial presentations are not available. [ABSTRACT FROM AUTHOR]

Microscopic evaluation of hematoxylin and eosin-stained slides is still the diagnostic gold standard for a variety of diseases, including neoplasms. Nevertheless, intra- and interrater variability are well documented among pathologists. So far, computer assistance via automated image analysis has shown potential to support pathologists in improving accuracy and reproducibility of quantitative tasks. In this proof of principle study, we describe a machine-learning-based algorithm for the automated diagnosis of 7 of the most common canine skin tumors: trichoblastoma, squamous cell carcinoma, peripheral nerve sheath tumor, melanoma, histiocytoma, mast cell tumor, and plasmacytoma. We selected, digitized, and annotated 350 hematoxylin and eosin-stained slides (50 per tumor type) to create a database divided into training, n = 245 whole-slide images (WSIs), validation (n = 35 WSIs), and test sets (n = 70 WSIs). Full annotations included the 7 tumor classes and 6 normal skin structures. The data set was used to train a convolutional neural network (CNN) for the automatic segmentation of tumor and nontumor classes. Subsequently, the detected tumor regions were classified patch-wise into 1 of the 7 tumor classes. A majority of patches-approach led to a tumor classification accuracy of the network on the slide-level of 95% (133/140 WSIs), with a patch-level precision of 85%. The same 140 WSIs were provided to 6 experienced pathologists for diagnosis, who achieved a similar slide-level accuracy of 98% (137/140 correct majority votes). Our results highlight the feasibility of artificial intelligence-based methods as a support tool in diagnostic oncologic pathology with future applications in other species and tumor types. [ABSTRACT FROM AUTHOR]

Sulfate aerosol in the stratosphere is an important climate driver, causing solar dimming in the years after major volcanic eruptions. Hence, a growing number of general circulation models are adapting interactive sulfur and aerosol schemes to improve the representation of relevant chemical processes and associated feedbacks. However, uncertainties of these schemes are not well constrained. Stratospheric sulfate is modulated by natural emissions of sulfur-containing species, including volcanic eruptive, and anthropogenic emissions. Model intercomparisons have examined the effects of volcanic eruptions, whereas the background conditions of the sulfur cycle have not been addressed in a global model intercomparison project. Assessing background conditions in global models allows us to identify model discrepancies as they are masked by large perturbations such as volcanic eruptions, yet may still matter in the aftermath of such a disturbance. Here, we analyze the atmospheric burden, seasonal cycle, and vertical and meridional distribution of the main sulfur species among nine global atmospheric aerosol models that are widely used in the stratospheric aerosol research community. We use observational and reanalysis data to evaluate model results. Overall, models agree that the three dominant sulfur species in terms of burdens (sulfate aerosol, OCS, and SO2) make up about 98 % of stratospheric sulfur and 95 % of tropospheric sulfur. However, models vary considerably in the partitioning between these species. Models agree that anthropogenic emission of SO2 strongly affects the sulfate aerosol burden in the Northern Hemispheric troposphere, while its importance is very uncertain in other regions. The total deposition of sulfur varies among models, deviating by a factor of two, but models agree that sulfate aerosol is the main form in which sulfur is deposited. Additionally, the partitioning between wet and dry deposition fluxes is highly model dependent. We investigate the areas of greatest variability in the sulfur species burdens and find that inter-model variability is low in the tropics and increases towards the poles. Seasonality in the southern hemisphere is depicted very similar among models. Differences are largest in the dynamically active northern hemispheric extratropical region, hence some of the differences could be attributed to the differences in the representation of the stratospheric circulation among underlying general circulation models. This study highlights that the differences in the atmospheric sulfur budget among the models arise from the representation of both chemical and dynamical processes, whose interplay complicates the bias attribution. Several problematic points identified for individual models are related to the specifics of the chemistry schemes, model resolution, and representation of cross-tropopause transport in the extratropics. Further model intercomparison research is needed focusing on the clarification of the reasons for biases, given also the importance of this topic for the stratospheric aerosol injection studies. [ABSTRACT FROM AUTHOR]

Rapid and simple estimation of the mass eruption rate (MER) from column height is essential for real‐time volcanic hazard management and reconstruction of past explosive eruptions. Using 134 eruptive events from the new Independent Volcanic Eruption Source Parameter Archive (IVESPA, v1.0), we explore empirical MER‐height relationships for four measures of column height: spreading level, sulfur dioxide height, and top height from direct observations and as reconstructed from deposits. These relationships show significant differences and highlight limitations of empirical models currently used in operational and research applications. The roles of atmospheric stratification, wind, and humidity remain challenging to detect across the wide range of eruptive conditions spanned in IVESPA, ultimately resulting in empirical relationships outperforming analytical models that account for atmospheric conditions. This finding highlights challenges in constraining the MER‐height relation using heterogeneous observations and empirical models, which reinforces the need for improved eruption source parameter data sets and physics‐based models. Plain Language Summary: Explosive volcanic eruptions expel gas and tephra in the form of a volcanic column (or plume) that rises into the atmosphere. Two important metrics characterizing these eruptions are the maximum rise height and the eruptive intensity, that is, the rate at which material is emitted from the eruptive vent. Understanding the relationship between these parameters is critical for reconstructing past volcanic events and managing hazards during volcanic crises. In this study, we use a new database of well‐characterized eruptions to constrain simple relationships between column height and eruptive intensity. We distinguish four different measurements of column height: the maximum height reached by tephra from observations and from analysis of deposits, the height at which ash spreads in the atmosphere, and the height reached by volcanic sulfur gases. We show that each height category has a distinct relationship with the eruption intensity, enabling volcanologists and risk managers to use the relationship most appropriate to the measurements available to them. Despite the improved level of detail, our data set cannot resolve any systematic influence of atmospheric conditions such as wind and humidity on eruption column height, highlighting difficulties in measuring volcanic eruption characteristics and understanding their dynamics. Key Points: We provide empirical scaling relationships between mass eruption rate (MER) and column height using a new database with 134 volcanic eventsWe constrain bespoke relationships and their uncertainties for four height metrics to support ash dispersion forecasters and researchersWe detect no clear atmospheric influence on scaling relationships, highlighting required improvements of scaling models and the database [ABSTRACT FROM AUTHOR]

Volcanic and wildfire events between 2014 and 2022 injected ∼3.2 Tg of sulfur dioxide and 0.8 Tg of smoke aerosols into the stratosphere. With injections at higher altitudes and lower latitudes, the simulated stratospheric lifetime of the 2014–2022 injections is about 50% longer than the volcanic 2005–2013 injections. The simulated global mean effective radiative forcing (ERF) of 2014–2022 is −0.18 W m−2, ∼40% of the ERF of the period of 1991–1999 with a large‐magnitude volcanic eruption (Pinatubo). Our climate model suggests that the stratospheric smoke aerosols generate ∼60% more negative ERF than volcanic sulfate per unit aerosol optical depth. Studies that fail to account for the different radiative properties of wildfire smoke relative to volcanic sulfate will likely underestimate the negative stratospheric forcings. Our analysis suggests that stratospheric injections offset 20% of the increase in global mean surface temperature between 2014–2022 and 1999–2002. Plain Language Summary: Between 2014 and 2022, volcanic and wildfire events injected about ∼3.2 Tg of sulfur dioxide and 0.8 Tg of smoke aerosols into the stratosphere, about 30%–40% of injected mass of the 1991 Pinatubo eruption. Because the sulfur dioxide and smoke aerosols are injected at higher altitudes and lower latitudes, the simulated aerosol lifetime is 50% longer than the volcanic injections between 2005 and 2013, which have been suggested to play a role in the global warming hiatus. Our climate model suggests that smoke aerosol generates 60% more negative effective radiative forcing compared with volcanic sulfate aerosol per unit change in aerosol optical depth. Our study underscores the distinct optical properties between the wildfire smoke and sulfate aerosol. Our analysis finds that the trend of the global mean surface temperature in the two decades would have been 24% larger without the stratospheric injections. Key Points: Long‐term balloon‐borne measurements of stratospheric aerosol over Tibetan Plateau and U.S. are compared with an aerosol‐climate modelStratospheric smoke particles generate 60% more negative effective radiative forcing than volcanic sulfate with the same aerosol optical depthStratospheric aerosol abundance offsets 20% of the increase in the global mean surface temperature between 2014–2022 and 1999–2002 [ABSTRACT FROM AUTHOR]