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Methane clumped isotope signatures of abiogenesis may be diagnostic of the origin of methane on Earth and other planetary bodies. We performed synthesis of abiogenic methane in hydrothermal conditions between 130 and 300°C and determined δ13C, δD, Δ13CH3D, and Δ12CH2D2. The experiments were performed by heating water in the presence of Fe0 powder and CO. The reduction of water on metallic iron led to the formation of H2. CO was reacted with both H2 and H2O, generating both CH4 and CO2. Methane δ13C values are isotopically depleted by ∼25‰ relative to the CO starting material. This is consistent with carbon isotopic equilibrium between methane, carbon monoxide and carbon dioxide in our experiments. In contrast, D/H ratios are inconsistent with equilibrium isotopic fractionation, as illustrated by δD values of methane fractionated by ∼500‰ relative to starting H2O. This suggests that under our experimental conditions, hydrogen additions to carbon may be governed by kinetics. Δ13CH3D values track experimental temperature, with values between +1.5‰ and +5.0‰ for most samples. In contrast, Δ12CH2D2 values are displaced from equilibrium. We find exclusively negative Δ12CH2D2 values, showing deficits down to 40‰ relative to thermodynamic equilibrium. We interpret the data as evidence for distinct, kinetically induced D/H pools contributing to methane assembly, that is, a combinatorial effect. The cumulative D/H fractionations associated with CO hydrogenation explain the direction and magnitude of Δ12CH2D2 values during abiotic methane formation. We suggest that near equilibrium Δ13CH3D with negative Δ12CH2D2 signatures will help identify methane formed abiotically in nature. Plain Language Summary: Methane is observed in various environmental settings on Earth, including but not limited to, hydrothermal fluids and sedimentary systems. It is also found on other worlds, as it was reported to occur on Mars, in Enceladus's geysers, and as of recently, in an exoplanet's atmosphere. Methane may be formed by life or by non‐biological processes, so the presence of methane alone on another world is not enough to declare a planet habitable. Geochemists have built methods to tell biogenic from abiotic methane, which ought to be useful for the identification of life‐derived methane on another planet. Those techniques are crucial but complex, based on integrated studies combining molecular and isotopic compositions of methane and associated gases. Here, we report on whether abiotic methane shows a unique signature for 13CH3D and 12CH2D2, the mass‐18 isotopologues of methane. We performed synthesis of abiotic methane in the laboratory and determined its composition. We observe unique signatures for methane clumping, where 12CH2D2 disequilibrium is associated with equilibrium 13CH3D abundances. We suggest that near equilibrium Δ13CH3D with negative Δ12CH2D2 signatures will help identify methane formed abiotically on Earth and on other worlds. Key Points: Synthesis of abiotic methane in the laboratory via a controlled Fischer‐Tropsch process under hydrothermal conditions carbon isotope equilibrium and hydrogen isotope disequilibrium during methane assembly13CH3D equilibration associated with substantial 12CH2D2 disequilibrium. Abiosignatures identified with combined 13CH3D and 12CH2D2 [ABSTRACT FROM AUTHOR]

Cortical networks exhibit complex stimulus-response patterns that are based on specific recurrent interactions between neurons. For example, the balance between excitatory and inhibitory currents has been identified as a central component of cortical computations. However, it remains unclear how the required synaptic connectivity can emergeindevelopingcircuitswheresynapsesbetweenexcitatoryandinhibitoryneurons are simultaneously plastic. Using theory and modeling, we propose that a wide range of cortical response properties can arise from a single plasticity paradigm that acts simultaneously at all excitatory and inhibitory connections--Hebbian learning that is stabilized by the synapse-type-specific competition for a limited supply of synaptic resources. In plastic recurrent circuits, this competition enables the formation and decorrelation of inhibition-balanced receptive fields. Networks develop an assembly structure with stronger synaptic connections between similarly tuned excitatory and inhibitory neurons and exhibit response normalization and orientation-specific centersurround suppression, reflecting the stimulus statistics during training. These results demonstrate how neurons can self-organize into functional networks and suggest an essential role for synapse-type-specific competitive learning in the development of cortical circuits. [ABSTRACT FROM AUTHOR]

Minimally invasive extended totally extraperitoneal (eTEP) technique is revolutionising ventral hernia repairs. Robotic-assisted eTEP has been gaining popularity due to better visual clarity and greater dexterity provided by the robotic systems, compared to laparoscopy. Despite growing number of papers being published each year, so far, no study has explored intraoperative complications in robotic-assisted eTEP. The aim was to perform a systematic literature review on the incidence of intraoperative complications in robotic-assisted eTEP ventral hernia repairs. The study protocol was preregistered with PROSPERO, registration number CRD42023450072. Twelve categories of intraoperative complications were defined by the authors. A search of PubMed and Embase was conducted on 16/08/2023, for articles pertaining to robotic-assisted eTEP operations in ventral hernias in adults. Articles were critically appraised and data were extracted using predefined extraction templates. No data were suitable for statistical analysis and a narrative synthesis was performed instead. Ten studies fulfilled the inclusion criteria, of which four studies reported intraoperative complications. Of the 12 categories of intraoperative complications, only 5 were reported. Three studies encountered adherent bowel inside the hernia sac. One reported linea alba injury with subsequent anterior layer dehiscence. There was one case of unrecognised intraoperative retromuscular bleeding and one case of insufflation injury with subcutaneous emphysema. There is a paucity of literature on the incidence of intraoperative complications in robotic-assisted eTEP ventral hernia repairs. Available studies suggest complication rates are low. More robust studies using prospective data from hernia registries are required before further conclusions can be drawn. [ABSTRACT FROM AUTHOR]

Simple Summary: There has been an exponential rise in the availability of artificial intelligence systems in endoscopy in recent years. As a result, maintaining an informed understanding of the utility and efficacy of existing systems has become increasingly complex. This review aims to summarise the expanse of research in this area to guide proceduralists in making informed decisions regarding the use of artificial intelligence in colonoscopy. It focuses primarily on the application of artificial intelligence for the detection and characterisation of colorectal polyps in order to improve the efficacy of colorectal cancer screening and prevention. Colorectal cancer remains a leading cause of cancer-related morbidity and mortality worldwide, despite the widespread uptake of population surveillance strategies. This is in part due to the persistent development of 'interval colorectal cancers', where patients develop colorectal cancer despite appropriate surveillance intervals, implying pre-malignant polyps were not resected at a prior colonoscopy. Multiple techniques have been developed to improve the sensitivity and accuracy of lesion detection and characterisation in an effort to improve the efficacy of colorectal cancer screening, thereby reducing the incidence of interval colorectal cancers. This article presents a comprehensive review of the transformative role of artificial intelligence (AI), which has recently emerged as one such solution for improving the quality of screening and surveillance colonoscopy. Firstly, AI-driven algorithms demonstrate remarkable potential in addressing the challenge of overlooked polyps, particularly polyp subtypes infamous for escaping human detection because of their inconspicuous appearance. Secondly, AI empowers gastroenterologists without exhaustive training in advanced mucosal imaging to characterise polyps with accuracy similar to that of expert interventionalists, reducing the dependence on pathologic evaluation and guiding appropriate resection techniques or referrals for more complex resections. AI in colonoscopy holds the potential to advance the detection and characterisation of polyps, addressing current limitations and improving patient outcomes. The integration of AI technologies into routine colonoscopy represents a promising step towards more effective colorectal cancer screening and prevention. [ABSTRACT FROM AUTHOR]

Background: Anti‐tumour necrosis factor alpha (anti‐TNF) agents are a highly effective treatment for inflammatory bowel disease (IBD). Skin lesions, including psoriasiform, eczematous and lupoid eruptions, may paradoxically result from anti‐TNF use and cause significant morbidity leading to discontinuation of therapy. There are no consensus guidelines on the management of these lesions. Aims: This systematic review considers the existing evidence regarding cutaneous complications of anti‐TNF therapy in IBD and the development of an algorithm for management. Methods: A systematic review was performed by searching Medline (Pubmed) and Embase for articles published from inception to January 2021. The following search terms were used 'anti‐tumour necrosis factor alpha', 'infliximab', 'adalimumab', 'certolizumab', 'golimumab', 'inflammatory bowel disease', 'Crohn disease', 'Ulcerative colitis', 'psoriasis', 'psoriasiform', 'dermatitis', 'lupus', 'skin lesion' and 'skin rash'. Reference lists of relevant studies were reviewed to identify additional suitable studies. Results: Thirty‐four studies were included in the review. Eczema can generally be managed with topical agents and the anti‐TNF can be continued, while the development of lupus requires immediate cessation of the anti‐TNF and consideration of alternative immunomodulators. Management of psoriasis and psoriasiform lesions may follow a step‐wise algorithm where topical treatments will be trialled in less severe cases, with recourse to an alternative anti‐TNF or a switch to an alternative class of biological agent. Conclusion: Assessment of anti‐TNF skin lesions should be performed in conjunction with a dermatologist and rheumatologist in complex cases. High‐quality prospective studies are needed to clarify the validity of these algorithms in the future. [ABSTRACT FROM AUTHOR]

Identification of methane origins remains a challenging work as current diagnostic signals are often not sufficient to resolve individual formation and post‐formation processes. To address such a knowledge gap in a tectonically active and fragmented terrain, samples from mud volcanoes, gas seeps, and springs distributed along structural features onshore and offshore of Taiwan were analyzed for their isotopic compositions of methane, nitrogen, helium, dissolved inorganic carbon, CO2, and water. Our analyses yielded Δ13CH3D and Δ12CH2D2 values ranging between +1.9‰ and +7.8‰ and between +3.0‰ and +19.9‰, respectively. A portion of the samples were characterized by values that represent the thermodynamic equilibrium at temperatures of 99°–260°C. These temperature estimates, together with the bulk isotopic compositions and local geothermal gradients (25°–30°C/km), suggest that methane was formed by thermal maturation of organic matter at depths of 2–9 km below the land surface and channeled upward along faults. Other samples were found to deviate from equilibrium by varying degrees. Considering the geological background, helium isotopic ratios, and nitrogen isotopologue compositions, and methanogens detected at some sites, these gases are either abiotic in origin or a mixture of microbial and thermogenic sources. Regardless of whether the equilibrium of methane isotopologues was reached, few sites hosted by sedimentary formations were characterized by mantle‐like helium signatures, indicating decoupled origins and potential degassing of helium from the relic igneous source. Overall, these results suggest the extraction of methane and other gases from multiple depths from strata fragmented by fault displacement in an active orogenic belt. Plain Language Summary: Mud volcanoes and gas seeps are distributed primarily in active tectonic regimes and represent the surface expression of subsurface fracture networks. They provide rapid access to probing subsurface characteristics for the generations of methane, other gases, and water. Identifying the exact mechanisms of methane formation remains a challenging work due to the lack of diagnostic signals with sufficient resolving power. This study employed a wide range of isotopic tools to constrain the origins of gases and water from mud volcanoes and seeps in Taiwan, where dual subductions and associated arc‐continent collision between the Philippine Sea and Eurasian plates have enabled the plumbing of gases and water in accordance with structure development and stratum deformation. Our results reveal a spectrum of geochemical characteristics that point to diverse formation mechanisms and conditions. In particular, deeply sourced thermogenic methane (from depths of 2–9 km) appears to constitute a major gas component at most sites, and is mixed by various degrees with abiotic methane pertinent to igneous bodies emplaced during subduction/collision, or microbial methane generated at shallow depths. Overall, the results address the temporal and spatial variations in gas origins prone to terrain fragmentation and dynamic structural control associated with mountain building. Key Points: Mud volcanoes and gas seeps provide rapid access to probing subsurface fluid characteristics in tectonically active regionsThermogenic methane constitutes a major component of hydrocarbons and forms at temperatures of 99°–260°CA wide spectrum of geochemical characteristics indicates diverse formation mechanisms and conditions that constrain gas and water origins [ABSTRACT FROM AUTHOR]

As the field of zirconium (Zr) stable isotopes is rapidly expanding from the study of mass-independent to that of mass-dependent isotope effects, a variety of Zr standards have appeared in the literature. While several of these standards have been proposed as the ideal isotope reference material (iRM) against which all data should be reported, none of them have been shown to meet the compositional and/or conflict-of-interest-free distribution requirements put forth by the community. To remedy this situation, we report on a community-led effort to develop and calibrate a scale defining iRM for Zr isotopes: NIST RM 8299. Developed in partnership with the National Institute of Standards and Technology (NIST) from the widely used SRM 3169 Zirconium Standard Solution (certified for mass fraction), the candidate RM 8299 was calibrated through an inter-laboratory study involving three laboratories. Our data show that candidate RM 8299 meets all requirements of an ideal iRM. It is an isotopically homogeneous, high-purity reference material, that is free of isotope anomalies, and whose composition is identical to that of a major geological reservoir (Ocean Island Basalts). Furthermore, RM 8299 will be curated and distributed by NIST, a neutral, conflict-of-interest free organization, and was produced in sufficient quantities to last multiple decades. We recommend that all Zr isotope data be reported against RM 8299. Our results also show that SRM 3169 lots #130920 and #071226 have indistinguishable composition compared to candidate RM 8299. Therefore, using RM 8299 as the scale defining iRM will enable direct comparison of all future data with the vast majority of the existing literature data, both for mass-independent and mass-dependent isotope effects. To facilitate conversion of δ94/90Zr values reported against other Zr standards, we provide high-precision conversion factors to the RM 8299 scale obtained using the double-spike method. [ABSTRACT FROM AUTHOR]

Sub-Neptune exoplanets are commonly hypothesized to consist of a silicate-rich magma ocean topped by a hydrogen-rich atmosphere. Previous work studying the outgassing of silicate material has demonstrated that such atmosphere–interior interactions can affect the atmosphere's overall structure and extent. However, these models only considered SiO in an atmosphere of hydrogen gas, without considering chemical reactions between them. Here, we couple calculations of the chemical equilibrium between H, Si, and O species with an atmospheric structure model. We find that substantial amounts of silane, SiH4, and water, H2O, are produced by the interaction between the silicate-rich interior and hydrogen-rich atmosphere. These species extend high into the atmosphere, though their abundance is greatest at the hottest, deepest regions. For example, for a 4 M⊕ planet with an equilibrium temperature of 1000 K, a base temperature of 5000 K, and a 0.1 M⊕ hydrogen envelope, silicon species and water can comprise 30 per cent of the atmosphere by number at the bottom of the atmosphere. Due to this abundance enhancement, we find that convection is inhibited at temperatures ≳2500 K. This temperature is lower, implying that the resultant non-convective region is thicker, than was found in previous models that did not account for atmospheric chemistry. Our findings show that significant endogenous water is produced by magma–hydrogen interactions alone, without the need to accrete ice-rich material. We discuss the observability of the signatures of atmosphere–interior interaction and directions for future work, including condensate lofting and more complex chemical networks. [ABSTRACT FROM AUTHOR]

The short-lived radionuclide aluminium-26 (26Al) isotope is a major heat source for early planetary melting. The aluminium-26 – magnesium-26 (26Al-26Mg) decay system also serves as a high-resolution relative chronometer. In both cases, however, it is critical to establish whether 26Al was homogeneously or heterogeneously distributed throughout the solar nebula. Here we report a precise lead-207 – lead-206 (207Pb-206Pb) isotopic age of 4565.56 ± 0.12 million years (Ma) for the andesitic achondrite Erg Chech 002. Our analysis, in conjunction with published 26Al-26Mg data, reveals that the initial 26Al/27Al in the source material of this achondrite was notably higher than in various other well-preserved and precisely dated achondrites. Here we demonstrate that the current data clearly indicate spatial heterogeneity of 26Al by a factor of 3-4 in the precursor molecular cloud or the protoplanetary disk of the Solar System, likely associated with the late infall of stellar materials with freshly synthesized radionuclides. The homogeneity of Aluminium-26 (Al-26) isotope distribution in the accreting solar nebula is debated. Here, the authors show that the age determination of meteorite Erg Chech 002, compared with other igneous meteorites, indicates that Al-26 was heterogeneously distributed in the early Solar System. [ABSTRACT FROM AUTHOR]

We present observations and analyses of eight white dwarf stars (WDs) that have accreted rocky material from their surrounding planetary systems. The spectra of these helium-atmosphere WDs contain detectable optical lines of all four major rock-forming elements (O, Mg, Si, and Fe). This work increases the sample of oxygen-bearing WDs with parent body composition analyses by roughly 33%. To first order, the parent bodies that have been accreted by the eight WDs are similar to those of chondritic meteorites in relative elemental abundances and oxidation states. Seventy-five percent of the WDs in this study have observed oxygen excesses implying volatiles in the parent bodies with abundances similar to those of chondritic meteorites. Three WDs have oxidation states that imply more reduced material than found in CI chondrites, indicating the possible detection of Mercury-like parent bodies, but are less constrained. These results contribute to the recurring conclusion that extrasolar rocky bodies closely resemble those in our solar system, and do not, as a whole, yield unusual or unique compositions. [ABSTRACT FROM AUTHOR]

Background: Colorectal adenocarcinoma is an important and preventable complication of inflammatory bowel disease (IBD). A previous case series suggested mental health issues and poor engagement in care as novel risk factors. Aims: To confirm the role of patient engagement in care in the development of neoplasia using a case‐control methodology. Methods: Patients in a single referral centre from 2007 to 2017 with colorectal adenocarcinoma, high‐grade dysplasia or multifocal low‐grade dysplasia were included as neoplasia cases. Each case was assigned up to three matched controls (matched for age, gender, underlying disease, IBD type and phenotype and disease duration). Novel and known risk factors were compared between groups. Results: Thirty‐two cases with 88 matched controls were included. Patients with neoplasia were more likely to have poor adherence to, or engagement with, care (odds ratio (OR) 4.79). They were also more likely to have chronic use of opioids (OR 3.86) and long‐term prednisolone (OR 2.97). Of note, no difference was found in measures of socioeconomic disadvantage, reflecting equitable access to healthcare in the public institution where the care was studied. As previously shown, patients with neoplasia had multiple markers of increased cumulative burden of inflammation, including more IBD‐related hospital admissions, elevated inflammatory markers and severe inflammation at colonoscopy. Conclusions: This study confirms poor adherence or engagement with care as a new risk factor for colorectal adenocarcinoma in patients with IBD; identifying a vulnerable group whom clinicians should endeavour to engage in order to avoid this catastrophic complication. [ABSTRACT FROM AUTHOR]

Earth’s water, intrinsic oxidation state and metal core density are fundamental chemical features of our planet. Studies of exoplanets provide a useful context for elucidating the source of these chemical traits. Planet formation and evolution models demonstrate that rocky exoplanets commonly formed with hydrogen-rich envelopes that were lost over time1. These findings suggest that Earth may also have formed from bodies with hydrogen-rich primary atmospheres. Here we use a self-consistent thermodynamic model to show that Earth’s water, core density and overall oxidation state can all be sourced to equilibrium between hydrogen-rich primary atmospheres and underlying magma oceans in its progenitor planetary embryos. Water is produced from dry starting materials resembling enstatite chondrites as oxygen from magma oceans reacts with hydrogen. Hydrogen derived from the atmosphere enters the magma ocean and eventually the metal core at equilibrium, causing metal density deficits matching that of Earth. Oxidation of the silicate rocks from solar-like to Earth-like oxygen fugacities also ensues as silicon, along with hydrogen and oxygen, alloys with iron in the cores. Reaction with hydrogen atmospheres and metal–silicate equilibrium thus provides a simple explanation for fundamental features of Earth’s geochemistry that is consistent with rocky planet formation across the Galaxy.Thermodynamic modelling shows that Earth’s water, core density and overall oxidation state can be explained by the formation of Earth from planetary embryos with hydrogen-rich primary atmospheres and underlying magma oceans. [ABSTRACT FROM AUTHOR]

Polluted white dwarfs (WDs) offer a unique way to study the bulk compositions of exoplanetary material, but it is not always clear if this material originates from comets, asteroids, moons, or planets. We combine N -body simulations with an analytical model to assess the prevalence of extrasolar moons as WD polluters. Using a sample of observed polluted WDs, we find that the extrapolated parent body masses of the polluters are often more consistent with those of many solar system moons, rather than solar-like asteroids. We provide a framework for estimating the fraction of WDs currently undergoing observable moon accretion based on results from simulated WD planetary and moon systems. Focusing on a three-planet WD system of super-Earth to Neptune-mass bodies, we find that we could expect about one percent of such systems to be currently undergoing moon accretions as opposed to asteroid accretion. [ABSTRACT FROM AUTHOR]

Background: Emergency general surgery is an emerging public health issue globally, with substantial healthcare burden. Interhospital transfer of critically unwell surgical patients has been the mainstay of bridging gaps in surgical coverage in regional and rural locations, despite evidence of greater morbidity and mortality. Delays in transfer invariably occurs and compounds the situation. Our aim was to examine the factors influencing interhospital transfer delays in emergency general surgical patients. Methods: A systematic search of PubMED and EmBase, was performed by two researchers from 2020 to 23rd Feb 2021, for English articles related to interhospital transfer delays in emergency general surgical patients, with an age of >16. Articles were critically appraised and data were extracted into a pre‐specified data extraction form. No data was suitable for statistical analysis and a narrative synthesis was performed instead. Results: Six relevant articles were identified from the search. All studies were retrospective cohort studies with moderate to high risk of bias. Lack of consultant surgeon input, after hours transfer, need for intensive care bed and poor transfer documentation may have a role in interhospital transfer delays. Patients with public health insurance, multiple comorbidities and non‐emergency medical conditions experience longer transfer request time and may be at risk of precipitating interhospital transfer delays. Transfer delays are seen in transfers over longer distances. Conclusion: There is a paucity of knowledge on what and how factors influence interhospital transfer delays in emergency general surgical patients. Well‐designed prospective cohort studies are required to bridge this knowledge gap. [ABSTRACT FROM AUTHOR]

Background: Interhospital transfers in Australia facilitate access to acute surgical services, however transfer delays can occur. The aims of this study were to examine Australian mortality audit data on acute surgical patients who were transferred after presenting with a surgical emergency, and to identify modifiable predictors of transfer delay. Methods: Surgical admissions between 1 January 2001 and 18 August 2020 were retrospectively extracted from the Australian and New Zealand Audit of Surgical Mortality database. Relevant factors and themes of interest were collated. Results were presented as odds ratios (OR) and 95% confidence intervals (CI), with statistical significance defined as P <0.05. Results: After exclusion, a final 8270 cases were analysed. Non‐modifiable predictors identified were female gender (OR 1.34, 95% CI 1.05–1.70, P = 0.0184), comorbidities (OR 1.50, 95% CI 1.40–161, P <0.0001) and major non‐trauma non‐vascular specialty (OR 1.54 to 7.77, depending on specialty, P < 0.05). Modifiable predictors were inadequate clinical assessment (OR 49.48, 95% CI 32.91–74.38, P <0.0001), poor communication (OR 6.62, 95% CI 3.70–11.85, P <0.0001) and multiple transfers (OR 6.30, OR 95% 4.31–9.21, P <0.0001). Age, lack of bed and after‐hours transfer did not predict transfer delays. Metropolitan transfers was protective against transfer delays (OR 0.64, 95% CI 0.47–0.86, P = 0.0035). Conclusion: In the view of the receiving surgeon or assessor, all transfer delays potentially contributed to patient deaths, and may have been preventable. Strategies directed at modifiable factors could minimize delays. Increased surgical services in non‐metropolitan regions could reduce need for transfer. Prospective data is required to examine if the same predictors are observed in surgical patients who survive. [ABSTRACT FROM AUTHOR]

Eosinophilic esophagitis (EoE) is a leading cause of food bolus impaction in children and adults. The mechanism of dysphagia in EoE, particularly non-obstructive dysphagia, remains incompletely understood. While fibrostenotic processes appear to be critical in the development of dysphagia, somatosensory dysfunction and dysmotility also contribute. This review considers potential mechanisms of dysphagia and evaluates the utility of current and future treatment strategies in this context. [ABSTRACT FROM AUTHOR]

The trapped melt fractional crystallization model for the IIIAB iron meteorites put forward by J. T. Wasson two decades prior is revisited. The basic precepts upon which the model was based remain true, and the model can be implemented using Ir and Au solid/liquid distribution coefficients that are broadly consistent with experimental data. For this reason, the difference between the Wasson model and some more recent trapped melt models lies mainly with inferences about the S concentrations of the core of the IIIAB iron meteorite parent body. For the Wasson model, S bulk concentrations of about 2 wt% are implied. For the more recent model, much greater concentrations of between about 12–15 wt% are indicated. The two different trapped melt models profoundly influence the interpretation of high δ57Fe values relative to chondrites in the IIIAB irons. The Wasson model suggests that there should be more variations in δ57Fe than are observed among these meteorites, while the more recent trapped melt model relies on the crystallization of FeS from the trapped melt to raise the δ57Fe of the latter, thus minimizing the variability. The interpretation of Fe isotope ratios in the IIIAB meteorites therefore depends critically on the S concentration of the parent body core. [ABSTRACT FROM AUTHOR]

Background: The Lyell McEwin Hospital entered into a public–private collaborative agreement in 2019 in order to access Da Vinci® Xi Surgical Systems (Intuitive Surgical, Sunnyvale, CA, USA) in private hospitals. This study aimed to examine the costs associated with usage of robot surgical systems under the agreement, and the potential for acquisition in the public hospital. Methods: Retrospective data on robotic-assisted and equivalent operations performed between 1 May 2019 and 30 April 2020 were collected and formed subsequent model inputs. Cost data were from hospital records and the local Da Vinci® Xi distributor. Clinical workflow of operations was simulated with a decision-analytic model, with output being costs incurred. The model’s base case scenario assumed 5% of cases were robotically assisted. Results: A total of 35 robotic-assisted, 101 laparoscopic and 34 open operations were performed. Patients were predominantly male and overweight with multiple comorbidities. Length of stay and duration of operation were associated with increased costs (p < 0.001, r² 0.72). In the base case scenario, there was a cost of AU$26 424 per patient, with an open conversion rate of 11%. Increasing robotic-assisted case percentage resulted in reduced cost, open conversion rates and length of stay. Extrapolation of cost model data indicated if 50% were robotic-assisted cases, then the initial capital investment (assumed at AU$4 000 000) could be recovered in 10 years. Conclusion: Our model highlights potential advantages of performing greater numbers of robotic-assisted operations in a collaborative environment. Cost-effective analysis with prospective data could evaluate if these results are translatable and potentially support acquisition of robotic systems in the public sector. [ABSTRACT FROM AUTHOR]

In hyperalkaline (pH>10) fluids that have participated in low‐temperature (<150°C) serpentinization reactions, the dominant form of C is often methane (CH4), but the origin of this CH4 is uncertain. To assess CH4 origin in serpentinite aquifers within the Samail Ophiolite, Oman, we determined fluid chemical compositions, analyzed taxonomic profiles of fluid‐hosted microbial communities, and measured isotopic compositions of hydrocarbon gases. We found that 16S rRNA gene sequences affiliated with methanogens were widespread in the aquifer. We measured clumped isotopologue (CH313D and CH212D2) relative abundances less than equilibrium, consistent with substantial microbial CH4 production. Furthermore, we observed an inverse relationship between dissolved inorganic C concentrations and δ13CCH4 across fluids bearing microbiological evidence of methanogenic activity, suggesting that the apparent C isotope effect of microbial methanogenesis is modulated by C availability. An additional source of CH4 is evidenced by the presence of CH4‐bearing fluid inclusions in the Samail Ophiolite and our measurement of high δ13C values of ethane and propane, which are similar to those reported in studies of CH4‐rich inclusions in rocks from the oceanic lithosphere. In addition, we observed 16S rRNA gene sequences affiliated with aerobic methanotrophs and, in lower abundance, anaerobic methanotrophs, indicating that microbial consumption of CH4 in the ophiolite may further enrich CH4 in 13C. We conclude that substantial microbial CH4 is produced under varying degrees of C limitation and mixes with abiotic CH4 released from fluid inclusions. This study lends insight into the functioning of microbial ecosystems supported by water/rock reactions. Plain Language Summary: Mantle rocks from beneath Earth's crust can be thrust to the surface, where they are exposed to rain and air containing carbon dioxide (CO2). The groundwaters that become stored in these rocks often contain methane (CH4, a major component of "natural gas"), which can be formed from carbon dioxide in the subsurface. To investigate these methane‐forming processes, we sampled water, gas, and suspended particles from groundwaters using wells previously drilled into the rocks. The particles contained microbes with the genetic ability to produce methane. We also precisely measured the amounts of combinations of C and H atoms of different masses (isotopes) in the natural gas to determine how it was formed. The results of these measurements suggest that microbes could actively produce a considerable amount of the methane, which mixes with methane from another source that was formed by non‐biological processes, possibly long ago under different conditions than today's. Rocks like those studied here are widespread in the Solar System, so our finding that microbes live and produce methane in these rocks could help guide the search for life beyond Earth. Key Points: 16S rRNA gene sequences affiliated with methanogens and CH4 clumped isotopologue compositions suggest substantial microbial CH4 productionA second CH4 source, release of CH4 from fluid inclusions, is indicated by 13C‐enriched ethane and propaneC availability may influence the apparent C isotope effect of microbial methanogenesis [ABSTRACT FROM AUTHOR]

The element beryllium is detected for the first time in white dwarf stars. This discovery in the spectra of two helium-atmosphere white dwarfs was made possible only because of the remarkable overabundance of Be relative to all other elements, heavier than He, observed in these stars. The measured Be abundances, relative to chondritic, are by far the largest ever seen in any astronomical object. We anticipate that the Be in these accreted planetary bodies was produced by spallation of one or more of O, C, and N in a region of high fluence of particles of MeV or greater energy. [ABSTRACT FROM AUTHOR]

We utilize observations of 16 white dwarf stars to calculate and analyze the oxidation states of the parent bodies accreting onto stars. Oxygen fugacity, which is a measure of overall oxidation state for rocks, is as important as pressure and temperature in determining the structure of a planet. We find that most of the extrasolar rocky bodies formed under oxidizing conditions, but that ∼1/4 of the polluted white dwarfs have compositions that are consistent with more reduced parent bodies. The difficulty in constraining the oxidation states of relatively reduced bodies is discussed and a model for the time-dependent evolution of the apparent oxygen fugacity for a hypothetical reduced body engulfed by a WD is investigated. The differences in diffusive fluxes of various elements through the WD envelope yield spurious inferred bulk elemental compositions and oxidation states of the accreting parent bodies under certain conditions. The worst case for biasing against detection of reduced bodies occurs for high effective temperatures. For moderate and low effective temperatures, the evidence for relatively reduced parent bodies is preserved under most circumstances for at least several characteristic lifetimes of the debris disk. [ABSTRACT FROM AUTHOR]

A desktop superconducting series core reactor (SSR), made from Yttrium barium copper oxide (YBCO) tape, serves as a precursor to a scaled-up, grid-connected prototype unit. The SSR is intended as an alternative to the traditionally employed technologies, including superconducting fault current limiters, when managing fault levels on the electrical power grid. The philosophy of connecting a prototype SSR at a grid-connected research site is first presented before the focus shifts to the desktop SSR. The desktop SSR is a development step before the prototype unit, as it will confirm design construction methodologies and functionality. The desktop SSR is compared to both the fault limiting performance and power consumption of a copper reactor of similar geometry. It was found that the SSR reduced the impact of the applied fault, comparably to the air core reactor (5.9% variance), and was more than four times more energy efficient. Another significant advantage of the SSR would be the significantly reduced footprint required in a typical substation yard. [ABSTRACT FROM AUTHOR]

Background and Aims: Gastrointestinal (GI) adenocarcinoma, especially colorectal cancer (CRC), is a devastating complication of inflammatory bowel disease (IBD). We sought to examine the role of chronic inflammation and other possible predictors of the development of CRC, as well as assess as yet unexamined factors such as psychological comorbidity and engagement in care. Methods: This study included all patients involved in a tertiary hospital IBD service diagnosed with CRC between 2007 and 2017. Reports from histological specimens were assessed, and all those with adenocarcinoma, high‐grade dysplasia (HGD), or multifocal low‐grade dysplasia (LGD) originating within IBD‐affected mucosa were included in the study. Results: A total of 32 patients were included in the study (17 with adenocarcinoma and 15 with HGD/multifocal LGD). The majority had a duration of disease >20 years. Eleven patients (34%, CI 20–52%) had previous disease‐related surgery, and 16 (50%, CI 34–66%) had multiple previous disease‐related admissions. Thirteen patients (62%, CI 41–79%) had >50% of CRP results higher than 8 mg/L. Psychiatric comorbidities were common, with 19 patients (59%, CI 42–74%) having a psychiatric comorbidity or poor engagement in treatment. Conclusion: In this cohort, we have highlighted poor engagement, hesitation to up‐titrate therapy when indicated, and psychological comorbidities as likely contributors to poor disease control and development of GI adenocarcinoma. Based on our data, these easily identifiable clinical care factors should not be overlooked when addressing IBD‐related GI malignancy prevention. Additional research is required to assess a direct causal relationship, but this study would support the incorporation of psychology services into IBD clinics. [ABSTRACT FROM AUTHOR]

We report a case of human infection with a Brucella canis isolate in an adult in Canada who was receiving a biologic immunomodulating medication. We detail subsequent investigations, which showed that 17 clinical microbiology staff had high-risk exposures to the isolate, 1 of whom had a positive result for B. canis. [ABSTRACT FROM AUTHOR]

Background: Appendicectomy is a safe surgical procedure with minimal risks. Low mortality rates (0.04–0.24%) have been reported from a number of countries. Appendicectomy mortality rates have not been reported in Australia in recent years. The aim of the study was to conduct an appendicectomy mortality audit, to identify clinical management issues and to calculate the mortality rate of appendicectomy in Australia. Methods: This study analysed data from a peer review of appendicectomy deaths in Australian hospitals of all states and territories, from 2006 to 2017. Additional procedural data were obtained from the Australian Institute of Health and Welfare for the calculation of mortality rates. Results: The final analysis included 82 patients of whom 62 were elderly (age >65 years) with 47 males and 35 females. Two or more comorbidities were present in 68 patients. Open operation was performed in 62 patients, with complicated appendicitis found in 50 cases. The majority of management issues were non‐surgical. Of the 16 surgical management issues identified, 11 issues occurred post‐operatively in the elderly, which were potentially preventable. The overall mortality was 0.02% with 0.01% in the young (age <65 years) and 0.20% in the elderly. Conclusion: Australia's appendicectomy mortality rate was very low and comparable to international figures. Surgical management of appendicectomy was satisfactory in general. However, post‐operative care in the elderly was found to be poor at times, with room for improvement. Further research is needed whether improvements in post‐operative care could alter the clinical course to death in the elderly. [ABSTRACT FROM AUTHOR]

Almahata Sitta (AhS), an anomalous polymict ureilite, is the first meteorite observed to originate from a spectrally classified asteroid (2008 TC3). However, correlating properties of the meteorite with those of the asteroid is not straightforward because the AhS stones are diverse types. Of those studied prior to this work, 70–80% are ureilites (achondrites) and 20–30% are various types of chondrites. Asteroid 2008 TC3 was a heterogeneous breccia that disintegrated in the atmosphere, with its clasts landing on Earth as individual stones and most of its mass lost. We describe AhS 91A and AhS 671, which are the first AhS stones to show contacts between ureilitic and chondritic materials and provide direct information about the structure and composition of asteroid 2008 TC3. AhS 91A and AhS 671 are friable breccias, consisting of a C1 lithology that encloses rounded to angular clasts (<10 μm to 3 mm) of olivine, pyroxenes, plagioclase, graphite, and metal‐sulfide, as well as chondrules (~130–600 μm) and chondrule fragments. The C1 material consists of fine‐grained phyllosilicates (serpentine and saponite) and amorphous material, magnetite, breunnerite, dolomite, fayalitic olivine (Fo 28‐42), an unidentified Ca‐rich silicate phase, Fe,Ni sulfides, and minor Ca‐phosphate and ilmenite. It has similarities to CI1 but shows evidence of heterogeneous thermal metamorphism. Its bulk oxygen isotope composition (δ18O = 13.53‰, δ17O = 8.93‰) is unlike that of any known chondrite, but similar to compositions of several CC‐like clasts in typical polymict ureilites. Its Cr isotope composition is unlike that of any known meteorite. The enclosed clasts and chondrules do not belong to the C1 lithology. The olivine (Fo 75‐88), pyroxenes (pigeonite of Wo ~10 and orthopyroxene of Wo ~4.6), plagioclase, graphite, and some metal‐sulfide are ureilitic, based on mineral compositions, textures, and oxygen isotope compositions, and represent at least six distinct ureilitic lithologies. The chondrules are probably derived from type 3 OC and/or CC, based on mineral and oxygen isotope compositions. Some of the metal‐sulfide clasts are derived from EC. AhS 91A and AhS 671 are plausible representatives of the bulk of the asteroid that was lost. Reflectance spectra of AhS 91A are dark (reflectance ~0.04–0.05) and relatively featureless in VNIR, and have an ~2.7 μm absorption band due to OH− in phyllosilicates. Spectral modeling, using mixtures of laboratory VNIR reflectance spectra of AhS stones to fit the F‐type spectrum of the asteroid, suggests that 2008 TC3 consisted mainly of ureilitic and AhS 91A‐like materials, with as much as 40–70% of the latter, and <10% of OC, EC, and other meteorite types. The bulk density of AhS 91A (2.35 ± 0.05 g cm−3) is lower than bulk densities of other AhS stones, and closer to estimates for the asteroid (~1.7–2.2 g cm−3). Its porosity (36%) is near the low end of estimates for the asteroid (33–50%), suggesting significant macroporosity. The textures of AhS 91A and AhS 671 (finely comminuted clasts of disparate materials intimately mixed) support formation of 2008 TC3 in a regolith environment. AhS 91A and AhS 671 could represent a volume of regolith formed when a CC‐like body impacted into already well‐gardened ureilitic + impactor‐derived debris. AhS 91A bulk samples do not show a solar wind component, so they represent subsurface layers. AhS 91A has a lower cosmic ray exposure (CRE) age (~5–9 Ma) than previously studied AhS stones (11–22 Ma). The spread in CRE ages argues for irradiation in a regolith environment. AhS 91A and AhS 671 show that ureilitic asteroids could have detectable ~2.7 μm absorption bands. [ABSTRACT FROM AUTHOR]

The intrinsic oxygen fugacity of a planet profoundly influences a variety of its geochemical and geophysical aspects. Most rocky bodies in our solar system formed with oxygen fugacities approximately five orders of magnitude higher than that corresponding to a hydrogen-rich gas of solar composition. Here we derive oxygen fugacities of extrasolar rocky bodies from the elemental abundances in 15 white dwarf (WD) stars polluted by accretion of rocks. We find that the intrinsic oxygen fugacities of rocks accreted by the WDs are similar to those of terrestrial planets and asteroids in our solar system. This result suggests that at least some rocky exoplanets are geophysically and geochemically similar to Earth. [ABSTRACT FROM AUTHOR]

Background and Aim: Small bowel mucosal biopsies (SBBx) are routinely performed to investigate unexplained anemia; however, previous studies have demonstrated a low yield in diagnosing celiac disease. Our aim was to determine the yield of routine SBBx in a large cohort of patients who underwent gastroscopy for the investigation of anemia. Methods: Data from consecutive patients who underwent gastroscopy for the investigation of anemia in a tertiary hospital, from January 2008–December 2011, were prospectively collected. Measured outcomes were the prevalence of celiac disease, the yield of duodenal biopsies, and the correlation between celiac serology and diagnosis. Results: Over 4 years, 987 patients (385 M:602 F; 48.27 ± 15.89 years) underwent endoscopy for anemia, of which 534 (54.1%) had proven iron deficiency anemia (IDA). Abnormal SBBx consistent with celiac disease were found in 2% (22/987), with a higher prevalence in females (3.2%, n = 19 vs 0.8%, n = 3 in males) and in those with IDA (3.6%, n = 19 vs 0.7%, n = 3 in non‐IDA). Macroscopic endoscopic abnormalities were present in 86% (19/22) of patients with celiac disease. Of the 178 patients who had celiac serology, tissue transglutaminase antibody had the highest sensitivity (80%) and specificity (99%). Combined serology had a sensitivity of 85.7%. Conclusion: Only 2% of patients with unexplained anemia had abnormal SBBx consistent with celiac disease and even fewer patients in non‐IDA. Given the availability and high sensitivity of celiac serology and macroscopic changes on endoscopy, SBBx should not be routine during endoscopy but should be limited to those with positive celiac serology, abnormal endoscopic appearance, or females with IDA. Small bowel biopsies are regularly performed during the endoscopic investigation of anemia. Only 2% of patients with unexplained anemia in our study had abnormal small bowel biopsies consistent with celiac disease, and even fewer in anemia without iron deficiency. Given the availability and high sensitivity of celiac serology and macroscopic changes on endoscopy, small bowel biopsy should not be routine during endoscopy, but limited to those with positive celiac serology, abnormal endoscopic appearance or females with iron deficiency anemia (IDA). [ABSTRACT FROM AUTHOR]

The relative abundances of the radionuclides in the solar system at the time of its birth are crucial arbiters for competing hypotheses regarding the birth environment of the Sun. The presence of short-lived radionuclides, as evidenced by their decay products in meteorites, has been used to suggest that particular, sometimes exotic, stellar sources were proximal to the Sun's birth environment. The recent confirmation of neutron star - neutron star (NS-NS) mergers and associated kilonovae as potentially dominant sources of r-process nuclides can be tested in the case of the solar birth environment using the relative abundances of the longer-lived nuclides. Critical analysis of the 15 radionuclides and their stable partners for which abundances and production ratios are well known suggests that the Sun formed in a typical massive star-forming region (SFR). The apparent overabundances of short-lived radionuclides (e.g. 26Al, 41Ca, 36Cl) in the early solar system appears to be an artifact of a heretofore under-appreciation for the important influences of enrichment by Wolf-Rayet winds in SFRs. The long-lived nuclides (e.g. 238U, 244Pu, 247Cr, 129I) are consistent with an average time interval between production events of 108 years, seemingly too short to be the products of NS-NS mergers alone. The relative abundances of all of these nuclides can be explained by their mean decay lifetimes and an average residence time in the ISM of ∼200 Myr. This residence time evidenced by the radionuclides is consistent with the average lifetime of dust in the ISM and the timescale for converting molecular cloud mass to stars. [ABSTRACT FROM AUTHOR]

We present experimental data on the ac losses in Roebel cables with striated 2G REBCO strands. Electromagnetic measurements by pick-up coils were carried out at different temperatures between 10 K and 85 K at frequencies between 2 Hz and 20 kHz in transverse ac fields up to 0.5 T. The Roebel cable samples were assembled from laser cut 2G REBCO strands, which consist of striated filaments prepared with laser scribing. Measurements at different temperatures show that the Roebel cables with striated strands have a lower losses by a factor of strand filament number over the whole temperature range. For analysis, a semiquantitative approach for unstriated Roebel was found to work satisfactorily. However, the Striated Roebel cables appears to have a different field penetration from those of the unstriated Roebel. The coupling current among the filaments has a time constant shorter than 0.1 ms and do not appear to increase in the striated Roebel cables, hence insignificant for most magnets related applications. [ABSTRACT FROM AUTHOR]

We present a theoretical model to investigate the potential of 13CH3D and 12CH2D2, the doubly substituted mass-18 isotopologues of methane, as tools for tracking atmospheric methane sources and sinks. We use electronic structure methods to estimate kinetic isotope fractionations associated with the major sink reactions of methane in air (reactions with OH and Cl radicals) and combine literature data with reconnaissance measurements of the relative abundances of 13CH3D and 12CH2D2 to estimate the compositions of the largest atmospheric sources. This model atmospheric budget is investigated with a simplified box model in which we explore both steady state and dynamical (nonsteady state) conditions triggered by changes in emission or sink fluxes. The steady state model predicts that sink reactions will generate a marked (>100‰) clumped isotope excess in atmospheric Δ12CH2D2 relative to the net source composition. 12CH2D2 measurements may thus be useful for tracing both atmospheric source and sink fluxes. The effect of sinks on Δ13CH3D is much less pronounced, indicating that 13CH3D in air will give a more focused picture of the source composition. [ABSTRACT FROM AUTHOR]

Thermal stability is an essential parameter for coil design. Previous measurements in an MgB2 solenoid have revealed a change in trend in the minimum quench energy (MQE) dependence on j= I/ Ic showing lower values than expected for operative current close to the critical current (j ∼ 0.90). The obtained MQE is comparable to the one predicted by analytical models in a single tape (1D) being of the order of 1–10 mJ, which indicates that propagation across winding and layers (3D) is not taking place. This reduction of MQE is not obtained in the effective continuum model, because the different turns and layers are not reproduced. Obtaining 1D propagation depends on the ratio between the thermal conductivity of the conductor and insulation and on the cooling conditions at the boundary layers. A numerical model of a superconducting solenoid with full representation of the winding is used to study MQE as a function of j (0.6–0.99). The quench is triggered applying heat pulses of 40 ms in a region of 4 mm of the outer layer of the coil. The effect of changing the cooling boundary conditions of the coil from adiabatic to isothermal is also investigated. [ABSTRACT FROM PUBLISHER]

High-current superconducting links (SC-Link) consisting of multiple MgB2 cables are being developed for the cold powering of the high luminosity upgrade of the LHC (HL-LHC). The SC-Links are designed to work over a temperature gradient between 4.2 and 20 K cooled by flowing subcritical helium gas to provide up to 20 kA per cable to the new inner-triplets to gain a higher luminosity. The SC-Links have a compact configuration of six 20-kA cables for three magnet circuits and several lower current cables. Upon the quench of one magnet, the neighboring circuits are exposed to a transient field up to 0.3 T, which may induce significant magnetization and coupling current losses with the potential of quenching the cables in these circuits. In this paper, we present a thermoelectrical analysis of the transient electromagnetics of the cable system, the thermal stability of the cables in temperature gradient, and the effect of lateral cooling by the flowing helium gas on the quench behavior. Furthermore, the analysis was compared with a comprehensive experimental study of direct thermometric and electrical measurements of the transient magnetic losses at different temperatures (4–30 K) and field sweep rates (0.3–30 T/s) as well as quench measurements under different cooling configurations. Cables samples of different stabilization matrices and strand configurations were measured to provide insight for the overall optimization by compromising between loss reduction and cryogenic stabilization. [ABSTRACT FROM PUBLISHER]

Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived 26Al in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a 26Al isochron with 26Al/27Al = 1.2(±0.2) × 10-5 for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule 26Al isochron because all chondrules analyzed so far with high precision (∼50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial (26Al/27Al) ≥ 1.2 × 10-5. In addition, mineral 26Al isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ∼2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule 26Al isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ∼1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate. [ABSTRACT FROM AUTHOR]