Rheology of magmas with bimodal crystal size and shape distributions: insights from analog experiments

Magmas in volcanic conduits commonly contain microlites in association with preexisting phenocrysts, as often indicated by volcanic rock textures. In this study, we present two different experiments that inves- tigate the flow behavior of these bidisperse systems. In the first experiments, rotational rheometric methods are used to determine the rheology of monodisperse and polydisperse suspensions consisting of smaller, prolate particles (microlites) and larger, equant particles (phenocrysts) in a bubble‐free Newtonian liquid (silicate melt). Our data show that increasing the relative proportion of prolate microlites to equant pheno- crysts in a magma at constant total particle content can increase the relative viscosity by up to three orders of magnitude. Consequently, the rheological effect of particles in magmas cannot be modeled by assuming a monodisperse population of particles. We propose a new model that uses interpolated parameters based on the relative proportions of small and large particles and produces a considerably improved fit to the data than earlier models. In a second series of experiments we investigate the textures produced by shearing bimodal suspensions in gradually solidifying epoxy resin in a concentric cylinder setup. The resulting textures show the prolate particles are aligned with the flow lines and spherical particles are found in well‐organized strings, with sphere‐depleted shear bands in high‐shear regions. These observations may explain the measured variation in the shear thinning and yield stress behavior with increasing solid fraction and particle aspect ratio. The implications for magma flow are discussed, and rheological results and tex- tural observations are compared with observations on natural samples

Why do dogs wag their tails?

Tail wagging is a conspicuous behaviour in domestic dogs (Canis familiaris). Despite how much meaning humans attribute to this display, its quantitative description and evolutionary history are rarely studied.We summarize what is known about the mechanism, ontogeny, function and evolution of this behaviour. We suggest two hypotheses to explain its increased occurrence and frequency in dogs compared to other canids. During the domestication process, enhanced rhythmic tail wagging behaviour could have (i) arisen as a by-product of selection for other traits, such as docility and tameness, or (ii) been directly selected by humans, due to our proclivity for rhythmic stimuli. We invite testing of these hypotheses through neurobiological and ethological experiments, which will shed light on one of the most readily observed yet understudied animal behaviours. Targeted tail wagging research can be a window into both canine ethology and the evolutionary history of characteristic human traits, such as our ability to perceive and produce rhythmic behaviours

Cooperation and cognition in wild canids

Canids are believed to be clever animals applying sophisticated social and hunting strategies. However, current studies under natural conditions do not indicate higher cognitive requirements beyond associative learning, but likely also underestimate them as applied methods are still in a fledgling stage. Experimental studies on captive canids — almost exclusively on wolves and dogs — indicate role understanding, perspective taking skills and numerical competence. However, such studies do not inform us if and how such skills are used in the wild. Apart from urging researchers to combine both approaches, we also highlight the need to investigate the embodied cognition of canids, as their specific ecological needs and perceptual capabilities likely led to specialised neuroethological pattern recognition skills

A novel method for the quantitative morphometric characterization of soluble salts on volcanic ash

<jats:title>Abstract</jats:title><jats:p>Formation of soluble sulfate and halide salts on volcanic ash particles via syn-eruptive interactions between ash surfaces and magmatic gases is a ubiquitous phenomenon in explosive eruptions. Surficial salts may be rapidly mobilized into their depositional environment undermining the quality of drinking water, harming aquatic life, and damaging soil and vegetation. Assessment of the potential for salt formation on ash and related environmental impacts have been based almost exclusively on bulk mineralogical or chemical analyses of ash; similarly, quantification of surficial salts has been made via leachate analysis only. However, it is the ash surface state and salt crystal properties that exert the predominant control on its reactivity, thus in determining their immediate environmental impact. Here, using scanning electron microscope (SEM) images, we present a novel image analysis protocol for the quantitative characterization of surficial salts, together with chemical analyses of resulting leachates. As volcanic ash proxies, we used synthetic rhyolitic glass particles (with systematic variations in FeO<jats:sub>T</jats:sub> and CaO content) and a crushed obsidian. Using an ash-gas reactor, we artificially surface-loaded samples with CaSO<jats:sub>4</jats:sub> and NaCl crystals, the most common crystal phases found on volcanic ash surfaces. Analogous variations were found using both methods: for CaSO<jats:sub>4</jats:sub> crystals, higher temperature treatments or increasing FeO<jats:sub>T</jats:sub> content at the same temperature led to higher concentrations of salt leachate and higher salt volumes; unexpectedly, increasing the CaO content caused only a minor increase in salt formation. In addition to bulk salt formation, morphometric results provided insight into formation processes, nucleation and growth rates, and limiting factors for salt formation. Higher temperatures increased CaSO<jats:sub>4</jats:sub> crystal size and surface coverage which we infer to result from higher element mobility in the glasses driving crystal growth. Increasing FeO<jats:sub>T</jats:sub> content of the glasses yielded increased salt surface coverage and leachate concentrations, but decreased crystal size (i.e., the salt number density increased). This latter effect likely relates to the role of iron as an electron-donor to charge balance salt-forming cation migration to the ash surface, indicating the importance of iron in determining surface reaction site density and, consequently, environmental reactivity. The controlling roles of ash composition and temperature on salt formation observed here can improve estimations for surface salt formation, volatile scavenging, and environmental impact for eruptions producing glass-rich ash. Our characterization protocol can therefore become a useful tool for the investigation of solid–gas reactions for terrestrial and planetary processes, and it also appears to be a powerful complement to research into atmospheric processes mediated by ash surfaces, such as ash aggregation and nucleation of water or ice on ash.</jats:p&gt

Desmoplastic small round cell tumor: impact of 18F-FDG PET induced treatment strategy in a patient with long-term outcome

The desmoplastic small round cell tumor (DSRCT) is an uncommon and highly aggressive cancer. The role of 18F-FDG PET in management of DSRCT is little reported. We report a case of metastasized abdominal DSRCT detected in a 43-year old patient whose diagnostic and therapeutic approaches were influenced by 18F-FDG PET-CT. The patient is still alive ten years after diagnosis. 18F-FDG PET-CT seems to be a useful method for assessing therapeutic efficiency and detecting early recurrences even in rare malignancies such as DSRCT

Vesiculation and Quenching During Surtseyan Eruptions at Hunga Tonga-Hunga Ha'apai Volcano, Tonga

Surtseyan eruptions are shallow to emergent subaqueous explosive eruptions that owe much of their characteristic behavior to the interaction of magma with water. The difference in thermal properties between water and air affects the cooling and postfragmentation vesiculation processes in magma erupted into the water column. Here we study the vesiculation and cooling processes during the 2009 and 2014–2015 Surtseyan eruptions of Hunga Tonga‐Hunga Ha'apai volcano by combining 2‐D and 3‐D vesicle‐scale analyses of lapilli and bombs and numerical thermal modeling. Most of the lapilli and bombs show gradual textural variations from rim to core. The vesicle connectivity in the lapilli and bombs increases with vesicularity from fully isolated to completely connected and also increases from rim to core in transitional clasts. We interpret the gradual textural variations and the connectivity‐vesicularity relationships as the result of postfragmentation bubble growth and coalescence interrupted at different stages by quenching in water. The measured vesicle size distributions are bimodal with a population of small and large vesicles. We interpret this bimodality as the result of two nucleation events, one prefragmentation with the nucleation and growth of large bubbles and one postfragmentation with nucleation of small vesicles. We link the thermal model with the textural variations in the clasts—showing a dependence on particle size, Leidenfrost effect, and initial melt temperature. In particular, the cooling profiles in the bombs are consistent with the gradual textural variations from rim to core in the clasts, likely caused by variations in time available for vesiculation before quenching

Clinical Features of Takotsubo Syndrome and Its Differential Diagnostic Criteria in Clinical Nursing Practice: A Review of the Literature

Purpose of Review: Takotsubo cardiomyopathy (TCM) is a heart disease that mimics the symptoms of a myocardial infarction (MI). The exact cause of TCM is unknown, but the main theory is that the syndrome is triggered by an excessive release of catecholamines, a consequence of factors related to stress or severe emotional distress. The aim of this review is to summarize the various scientific journal articles on the nursing differential diagnosis of TCM, on the specific nurse training (particularly the role of the Advanced Practice Nurse, APN), and on the nursing educational support for the patient after hospital discharge. Recent Findings: A literature review was conducted on Medline (via PubMed), Web of Science (WoS), Scopus, and Google Scholar databases. Relevant indexed articles that investigated the elements characterizing TCM in nursing differential diagnosis and the role of the APN were identified. Results: Sixteen studies were included in the review; they highlighted the role of the nurse in identifying and educating patients with TCM. Summary: Nurses must have a thorough understanding of the syndrome, the onset symptoms, the unusual characteristics, and the probable etiology of TCM in order to recognize and promptly treat patients affected by this syndrome and have the opportunity to educate them after hospital discharge to reduce the possibility of recurrence

The role of submarine volcanism in atmospheric chemistry

Funding: DBD and MC acknowledge the support of ERC 2018 ADV Grant 834225 (EAVESDROP). CC acknowledges the support of ERC CON Grant 864052 (VOLTA). TM and TP acknowledge funding from NSFGEO-NERC grant "Sulfur cycling in subduction" (NSF award no. OCE-1933773; NERC award NE/T010940/1). GWM acknowledges funding from NERC grant "MeteorStrat" (NE/R011222), with support also from the UK National Centre for Atmospheric Science, via long-term science programme ACSIS (NE/N018001/1). ZT acknowledges support from the Leverhulme Trust (ECF-2022-396).Submarine volcanic eruptions can form subaerial plumes that reach the stratosphere. Despite this, the impact of submarine eruptions on climate remains unclear due to a lack of clear geological record, with the recent large-scale Hunga eruption on 15 January 2022 being considered as an isolated case. Here, we review the impact of submarine and subaerial volcanoes in island or coastal settings (i.e., near seawater) on volatile/aerosol loading in the stratosphere. Isotopic δ34S signatures of the Hunga ash suggest that CaSO4 salts on the ash surface are dominantly formed by the evaporation of seawater during the eruption. We infer that SO2 scavenging on volcanic ash did not play a major role in the lower-than-expected SO2 detected in the volcanic cloud. Chlorine isotopic compositions (δ37Cl) also argue in favor of a seawater-derived origin of the chlorides from ash leachates. Combining petrological, leachate, isotopic and thermal analysis data, we demonstrate a near-absence of halogen degassing from the Hunga magma prior to and during the eruption, and conclude that the chlorine and bromine contents of tropospheric and stratospheric volatile species very dominantly derive from seawater/sea salts. We generalize our findings to all submarine eruptions, and large-scale, non-submarine eruptions in island or coastal settings, and propose that these may commonly form volcanic clouds that incorporate seawater thereby leading to the injection of related components (water vapor, sea salts, halogens) into the stratosphere. This makes seawater inputs a serious consideration when evaluating the long-term impact of volcanoes on climate.Peer reviewe