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Enhanced phosphorus regeneration linked to Ediacaran ocean oxygenation
Get PDFFunding: This study was supported by the National Natural Science Foundation of China (41930320), the Chinese 111 project (B20011), the Deep-time Digital Earth Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth, China University of Geosciences (Beijing) (2652023001).Several pulses of ocean oxygenation events were recognized in the Ediacaran period. However, the intrinsic triggers behind them remain ambiguous. Here we report phosphorus speciation data from the Ediacaran Doushantuo Formation, South China, to elucidate the role of recycled phosphorus in driving ocean oxygenation. High ratios of organic carbon to organic phosphorus in all samples relative to the Redfield ratio generally imply preferential release of phosphorus during the remineralization of organic matter. Notably, ratios of organic carbon to reactive phosphorus exceed the Redfield ratio during purported oxygenation intervals, but fall mostly below or close to the Redfield ratio in the rest of the section. Quantitative calculations suggest that enhanced benthic and water-column recycling created a phosphorus influx into the ocean that was comparable to or outpaced that of weathering input. Our study provides empirical evidence for untangling the mechanisms of the Ediacaran oxygenation.Peer reviewe
Deoxyribonucleoside treatment rescues EtBr-induced mtDNA depletion in iPSC-derived neural stem cells with POLG mutations
Get PDFFunding: K.L. was supported by University of Bergen Meltzers Høyskolefonds (project number: 103517133) and Gerda Meyer Nyquist Guldbrandson og Gerdt Meyer Nyquists legat (project number: 103816102). L.A.B. was supported the Norwegian Research Council (project number: 229652), Rakel og Otto Kr.Bruuns legat and Gerda Meyer Nyquist Guldbrandson og Gerdt Meyer Nyquists legat. G.J.S. was partly supported by the Norwegian Research Council through its Centre of Excellence funding scheme (project number: 262613). The authors are also grateful to the family of Hallvard Auganes for donations to this research.Mutations in POLG, the gene encoding the catalytic subunit of the mitochondrial DNA (mtDNA) polymerase gamma (Pol-γ), lead to diseases driven by defective mtDNA maintenance. Despite being the most prevalent cause of mitochondrial disease, treatments for POLG-related disorders remain elusive. In this study, we used POLG patient-induced pluripotent stem cell (iPSC)-derived neural stem cells (iNSCs), one homozygous for the POLG mutation c.2243G>C and one compound heterozygous with c.2243G>C and c.1399G>A, and treated these iNSCs with ethidium bromide (EtBr) to study the rate of depletion and repopulation of mtDNA. In addition, we investigated the effect of deoxyribonucleoside (dNs) supplementation on mtDNA maintenance during EtBr treatment and post-treatment repopulation in the same cells. EtBr-induced mtDNA depletion occurred at a similar rate in both patient and control iNSCs, however, restoration of mtDNA levels was significantly delayed in iNSCs carrying the compound heterozygous POLG mutations. In contrast, iNSC with the homozygous POLG mutation recovered their mtDNA at a rate similar to controls. When we treated cells with dNs, we found that this reduced EtBr-induced mtDNA depletion and significantly increased repopulation rates in both patient iNSCs. These observations are consistent with the hypothesis that mutations in POLG impair mtDNA repopulation also within intact neural lineage cells and suggest that those with compound heterozygous mutation have a more severe defect of mtDNA synthesis. Our findings further highlight the potential for dNs to improve mtDNA replication in the presence of POLG mutations, suggesting that this may offer a new therapeutic modality for mitochondrial diseases caused by disturbed mtDNA homeostasis.Peer reviewe
Three worlds in one : Venus as a natural laboratory for the effect of rotation period on atmospheric circulation
Get PDFFunding: The authors are grateful to the UK Science and Technology Facilities Council for funding support through STFC grant ST/X001180/1.Because of its rotation period of 243 days, Venus is considered a slowly rotating planet. However, its persistent superrotating atmospheric jets, which increase in speed from surface to cloud tops, effectively set a faster rotation speed than the surface rotation. Using the Venus Planetary Climate Model and wind measurements taken by the Pioneer Venus entry probes, we show that the Rossby radius of deformation of the atmosphere varies with height. The atmosphere falls into three circulation regimes: (1) from the surface to 20 km, the Rossby radius of deformation exceeds the planetary radius and no Rossby waves form; (2) from 20 to 50 km, the tropical Rossby radius becomes smaller than the planetary radius, and a circulation regime characterized by a superrotating equatorial jet and mid-latitude Rossby gyres appears; (3) from 50 to 70 km, the extratropical Rossby radius becomes smaller than the planetary radius, the jet develops mid-latitude maxima, and the Rossby gyres shift to high latitudes. Studies of exoplanetary circulation regimes as a function of rotation period have repeatedly shown a similar progression. While observing the circulations of exoplanets to confirm these predictions is not currently possible, the presence of different circulation regimes on Venus and their dependence on altitude could be tested by observing campaigns. Such evidence would be the first observational support for the theory connecting differences in planetary rotation periods to circulation regime transitions and would ground predictions of exoplanet circulations in a validated framework.Peer reviewe
Applicability of using portable luminescence reader for rapid age-assessments of dune accumulation in the Thar desert, India
Get PDFFunding: S.N. thanks the Quaternary Research Association for supporting his attendance at the UK Luminescence and ESR conference in London (2022), where this work was initially presented. S.N. thanks the University of Manchester for funding towards the fieldwork. A.S. thanks the University of Manchester for SEED New Horizons Research and Scholarship funding for luminescence dating costs at the University of St Andrews.Reconstructing dunefield-scale palaeoenvironmental histories is important, particularly in the context of understanding the complexity of dune development under future climate and land use changes in the densely populated Thar Desert, India. Dunefield-scale investigations with sufficient sampling resolution to provide insights into the spatio-temporal variations in dune accumulation history are time and resource intensive using traditional chronological techniques. For this reason, this study utilises rapid-age estimates derived from portable optically stimulated luminescence reader signals (POSL). POSL signal characteristics suggest a similar provenance for all samples, demonstrating the feasibility of using calibrated POSL signal counts for rapid age estimates. Calibration of POSL BSL signals carried out using ages of 40 samples with previously established OSL chronologies from central and northern Thar and 4 new OSL ages from western Thar shows a good fit (linear regression, R2 = 0.89, RMSE = 1427 years). We also explore the use of POSL IRSL in the calibration, as well as calibrating POSL signals against established sample De. Any dependence on dune type, vegetated linear versus parabolic is also explored, as well as any dependence of outliers on sediment characteristics, such as organic content and carbonate content. We find that bulk sediment moisture attenuates POSL signals up to a threshold of ∼0.73% moisture by weight, corresponding to a 24% attenuation. Our calibration is used to investigate intra and inter-dune variability in accumulation on three vegetated linear dunes in arid western Thar (a further 118 samples). Eastern flanks of these dunes are younger and have a higher accumulation rate than the western flanks, suggesting an eastward migration of the dunes. This study demonstrates the utility of the POSL reader in undertaking large landscape scale studies where the volume of analysed samples can outweigh the reduced accuracy of the POSL based rapid-age estimates.Peer reviewe
A warmer environment can reduce sociability in an ectotherm
Get PDFFunding: The study was funded by a Natural Environment Research Council Grant (NE/N016734/1) awarded to KJP, NBM, SSK, and JL, as well as a grant from the Wellcome Trust Institutional Strategic Support Fund (ISSF) awarded to NP. SSK was supported by a NERC Advanced Fellowship (NE/J019100/1) and a European Research Council Starting Grant (640004).The costs and benefits of being social vary with environmental conditions, so individuals must weigh the balance between these trade-offs in response to changes in the environment. Temperature is a salient environmental factor that may play a key role in altering the costs and benefits of sociality through its effects on food availability, predator abundance, and other ecological parameters. In ectotherms, changes in temperature also have direct effects on physiological traits linked to social behaviour, such as metabolic rate and locomotor performance. In light of climate change, it is therefore important to understand the potential effects of temperature on sociality. Here, we took the advantage of a ‘natural experiment’ of threespine sticklebacks from contrasting thermal environments in Iceland: geothermally warmed water bodies (warm habitats) and adjacent ambient-temperature water bodies (cold habitats) that were either linked (sympatric) or physically distinct (allopatric). We first measured the sociability of wild-caught adult fish from warm and cold habitats after acclimation to a low and a high temperature. At both acclimation temperatures, fish from the allopatric warm habitat were less social than those from the allopatric cold habitat, whereas fish from sympatric warm and cold habitats showed no differences in sociability. To determine whether differences in sociability between thermal habitats in the allopatric population were heritable, we used a common garden breeding design where individuals from the warm and the cold habitat were reared at a low or high temperature for two generations. We found that sociability was indeed heritable but also influenced by rearing temperature, suggesting that thermal conditions during early life can play an important role in influencing social behaviour in adulthood. By providing the first evidence for a causal effect of rearing temperature on social behaviour, our study provides novel insights into how a warming world may influence sociality in animal populations.Peer reviewe
Believing in blood : menstruation, menopause, and Jewish-Christian relations in medieval religious texts
No full textThis thesis investigates the significance of menstruation, menopause, and motherhood within the context of Jewish-Christian relations in medieval religious texts. By examining the menstrual cycles of key biblical female figures – such as Eve, Mary, Sarah, Rachel, Judith, and the female personifications of Judaism and Christianity – this thesis undertakes a comparative analysis of biblical commentaries, Bible translations, religious narratives, and polemical writings. These texts, spanning Jewish and Christian sources from French-, German-, and Spanish-speaking regions between the eleventh and fifteenth centuries, demonstrate how both religions used menstruation to shape religious identity and reinforce perceptions of self and other. By focusing on shared biblical characters, my comparative examination seeks to understand how these menstrual cycles were treated, perceived, and discussed respectively in the two religions, highlighting parallels and differences between their mentalities and methodologies. This research contests prevailing interpretations that view menstruation negatively in medieval religious discourse and challenges the notion that Jews were solely victims in Judeo-Christian interactions. Instead, it illustrates that Jews actively engaged in cultural and theological dialogue with Christians, reflecting a nuanced relationship that both incorporated and rejected elements from each other's cultures and religious practices. Ultimately, these texts emerge as overlooked resources for exploring medieval perceptions of the menstrual cycle, contributing to a deeper understanding of the history of menstruation and of Jewish-Christian relations. This thesis emphasises menstruation’s significance as a force for creation rather than pollution
Immersive learning of cerebral visual impairment : understanding vision through dynamic immersive simulations
No full textMany different brain-based impairments of vision can affect how someone experiences the world. Those conditions, called Cerebral Visual Impairments (CVI) are often difficult to explain and understand as each individual has their own unique experience of how they see and how their conditions affect them. However, people with CVI benefit substantially if those close to them understand their condition well enough to know which simple steps will make their world easier to navigate, interpret and understand. This paper summarises efforts to create immersive virtual reality visualisations which help those without CVI to better understand various CVI conditions. Two environments types are explored; classrooms and a climate change museum. A visual interface has been created which simulates various effects of CVI. Through this mechanism the user tailors their experience by selecting different impairments and their level of severity which then reacts dynamically to the environment chosen. Through experiential learning from a perspective of the world differing from their own, users gain exposure to CVI and potentially understand changes they can make to better support those affected. Evaluation and feedback demonstrates the simulation’s effectiveness as a research platform in its ability to help refine understanding of the dynamic nature of the impairments. The simulation is also effecting in establishing change in understanding, potentially leading to broader accessibility standards in schools, public spaces and beyond
The egalitarian case for open borders : moral arbitrariness
Get PDFThis paper argues that recent debates on egalitarian objections to immigration restrictions overlook a crucial, powerful normative principle that underpins objections to inequalities: any inequalities between morally equal persons – whether in goods, resources, welfare but also in powers, statuses, rights, and freedoms – that arise from morally arbitrary factors are pro tanto unjust. This principle of moral arbitrariness is fundamental to both luck and relational egalitarianism yet is often missing from debates that apply such theories to migration ethics. The result of this omission is that certain arguments that purportedly reject luck egalitarian cases for open borders in fact fail since they fail to recognise the normative force of the principle of moral arbitrariness; yet, simultaneously, relational egalitarian cases for open borders are not fully successful since they fail to recognise that the principle of moral arbitrariness is required to distinguish immigration restrictions as unjust where other (relational) inequalities may not be. Hence, the overall argument of this paper is that the recognition of the principle of moral arbitrariness is essential for the success of both the luck and relational egalitarian cases, and thus a proper recognition of the full normative force and implications of this principle entails the egalitarian case for open borders indeed succeeds.Peer reviewe
Valerie Wayne, ed. Women’s Labour and the History of the Book in Early Modern England. London: Arden Shakespeare, 2020. xvi + 320 pp. $29.95. Paperback (ISBN 978-1-350-24663-8)
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Cenozoic proxy constraints on Earth system sensitivity to greenhouse gases
Get PDFFunding: This study was partially supported by the German Science Foundation priority program EarthShape: Earth Surface Shaping by Biota (SPP, 1801) Grants EH329/14-2 and EH329/23-1 to T.A.E and MU4188/3-1 and MU4188/1-1 to S.G.M.The long-term extent of the Earth system response to anthropogenic interference remains uncertain. However, the geologic record offers insights into this problem as Earth has previously cycled between warm and cold intervals during the Phanerozoic. We present an updated compilation of surface temperature proxies for several key time intervals to reconstruct global temperature changes during the Cenozoic. Our data synthesis indicates that Earth’s surface slowly cooled by ca. 9°C during the early Paleogene to late Neogene and that continent-scale ice sheets developed after global temperature dropped to less than 10°C above preindustrial conditions. Slow cooling contrasts with the steep decrease in combined radiative forcing from past CO2 concentrations, solar luminosity, and ocean area, which was close to preindustrial levels even as Earth remained in a much warmer state. From this, we infer that the Earth system was less sensitive to greenhouse gas forcing for most of the Cenozoic and that sensitivity must have increased by at least a factor of 2 during the Plio-Pleistocene. Our results imply that slow feedbacks will raise global surface temperatures by more than 3°C in the coming millennia, even if anthropogenic forcing is stabilized at the present-day value (2 W/m2), and that their impact will diminish with further warming.Peer reviewe
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