32151 research outputs found
Sort by
Europium traces the impact of high temperature hydrothermal systems on the early oceans
Get PDFFunding: SV and JK acknowledge funding from the FWF for project P34238. SVH acknowledges funding from NSFC (grant no. 42150610481 – The “Stromatolite Geochemical Archive”). EES acknowledges funding from a NERC Frontiers grant (NE/V010824/1) and from a Leverhulme Trust research grant (RPG-2022-313).Hydrothermal systems have been invoked as a major driver for the evolution of life, but the impact of hydrothermal fluids on Earth’s ancient oceans and their habitats remains ambiguous. Europium (Eu) enrichments trace high temperature hydrothermal fluids in rock archives and may serve as proxy for hydrothermal input into ancient oceans. Here, we provide Eu abundances from stromatolites and iron formations between 3.8 and 0.542 billion years (Ga) ago and reconstruct the impact of hydrothermal systems on shallow and deeper marine environments. Our results document a continuous decrease in positive Eu anomalies until 2.5 Ga ago, followed by almost complete disappearance, suggesting a decreasing impact of submarine hydrothermal systems on ancient oceans. Exceptional positive Eu excursions between 2.8 and 2.6 Ga, and potentially also at 3.5 and 2.2 Ga, are only preserved in deep marine settings and reflect magmatic pulses triggered by elevated upper mantle temperatures. Our results demonstrate the significance of high temperature hydrothermal systems on Archean seawater chemistry with implications for the supply of bio-essential elements. However, life in shallow marine environments was likely supported by fluxes from emerging continents, at the least from the Neoarchean onwards.Peer reviewe
Inhibitory circuit motifs in Drosophila larvae generate motor program diversity and variability
Get PDFFunding: This work was supported by 1) a Biotechnology and Biological Sciences Research Council (BBSRC) EASTBIO CASE PhD studentship awarded to J.F. (BB/M010996/1) (https://biology.ed.ac.uk/eastbio) 2) a University of St Andrews Rector’s Fund Award to C.R.G. (https://tinyurl.com/Rectors-Fund), 3) a BBSRC EASTBIO CASE PhD studentship awarded to W.V.S. (BB/M010996/1)(https://biology.ed.ac.uk/eastbio) and 4) a collaborative Research Grant funded by the Global Office at University of St Andrews and The Halle Institute for Global Research at Emory University awarded jointly to A.A.P. and S.R.P. https://tinyurl.com/StA-Emory-CRG.How do neural networks generate and regulate diversity and variability in motor outputs with finite cellular components? Here we examine this problem by exploring the role that inhibitory neuron motifs play in generating mixtures of motor programs in the segmentally organised Drosophila larval locomotor system. We developed a computational model that is constrained by experimental calcium imaging data. The model comprises single-compartment cells with a single voltage-gated calcium current, which are interconnected by graded excitatory and inhibitory synapses. Local excitatory and inhibitory neurons form conditional oscillators in each hemisegment. Surrounding architecture reflects key aspects of inter- and intrasegmental connectivity motifs identified in the literature. The model generates metachronal waves of activity that recapitulate key features of fictive forwards and backwards locomotion, as well as bilaterally asymmetric activity in anterior regions that represents fictive head sweeps. The statistics of inputs to competing command-like motifs, coupled with inhibitory motifs that detect activity across multiple segments generate network states that promote diversity in motor outputs, while at the same time preventing maladaptive overlap in motor programs. Overall, the model generates testable predictions for connectomics and physiological studies while providing a platform for uncovering how inhibitory circuit motifs underpin generation of diversity and variability in motor systems.Peer reviewe
A three boron doped B/O/N multi-resonant TADF emitter for improved reverse intersystem crossing rate and efficient pure blue organic light-emitting diodes
No full textFunding: S. W. thanks the China Scholarship Council (201906250199). D. C. acknowledges support from the China Postdoctoral Science Foundation (Grant No. 2022TQ0227) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20230508). X.-H. Z. acknowledges support from the National Natural Science Foundation of China (Grant No. 52130304) and the Collaborative Innovation Center of Suzhou Nano Science & Technology. E. Z.-C. acknowledges support from the Engineering and Physical Sciences Research Council (EPSRC; EP/Z535291/1, EP/W015137/1, and EP/W007517/1).Multiresonant thermally activated delayed fluorescence (MR-TADF) compounds exhibit significant potential as emitters in organic light-emitting diodes (OLEDs) due to their bright, narrowband emission, which provides a solution to the color saturation required by industry for ultra-high definition (UHD) displays. Here, we report the smallest three boron doped MR-TADF emitter ( TBDON ), a design that fuses two boron-contacting MR-TADF emitters, DOBNA and ADBNA-Me-Mes , together. The resulting emitter, TBDON , shows desirable narrowband pure blue emission (λPL = 472 nm with FWHM = 28 nm) and efficient TADF with efficient reverse intersystem crossing (RISC), supported by a relatively fast kRISC of 7.8 × 104 s−1. The OLED with TBDON showed a high maximum external quantum efficiency (EQEmax) of 24.4%, an EQE of 17.2% at 100 cd m−2, and Commission Internationale de l’Éclairage (CIE) coordinates of (0.14, 0.16). The ternary device employing DMAC-DPS as an assistant dopant showed improved performance with a higher EQEmax of 28.1% and milder efficiency roll-off with an EQE100/1000 of 24.4/17.5%. The high device performance demonstrates the promise of the proposed molecular design.Peer reviewe
The motion of a quasi-geostrophic ellipsoidal vortex in a background shear flow
Get PDFThis work examines the motion of a vortex in the presence of a background shear flow in three-dimensional quasi-geostrophic flows. This model is of importance as it idealises the leading order influence of distant vortices in a flow with many vortices. The quasi-geostrophic (QG) model is the simplest geophysical fluid dynamical model which contains two important features underpinning geophysical flows: the effects of the Earth’s rotation and density stratification. In this model the fluid flow is completely determined by a single materially conserved scalar quantity, the potential vorticity (PV).
It is shown that for a uniform ellipsoidal distribution of PV the motion of the ellipsoid may be reduced to the evolution of a symmetric 3 × 3 matrix, under the action of a 3 × 3 flow matrix. The latter involves both the background flow, which must be linear in Cartesian coordinates at the surface of the ellipsoid, and the self-induced flow.
The steady states for this system are determined. A full linear stability analysis of these steady states is performed over a broad range of parameter space. From this analysis we find that the dominant mode of instability is ellipsoidal and we are able to determine the most stable vortex parameters.
A theory for the evolution of a vortex within a weak, slowly time varying background flow is presented. Using this theory it is shown that a vortex may evolve, quasi-adiabatically, that is, it stays close to an equilibrium form associated with the instantaneous background flow.
Finally the evolution of a vortex with a distributed PV profile is examined. Using a numerical method which solves the QG equations in a triply-periodic domain, we diagnose the effects of stripping on the vortex from its onset up to the final destruction of the vortex by the background flow
Social and cultural considerations for the restoration of ‘lost’ tree species : the fall and rise of elm
Get PDFFunding: This work was funded by Defra through the Centre for Forest Protection.1. Attempts to address biodiversity loss have led to ecosystem and species restoration efforts. Tree species restoration is particularly relevant because of increasing threats from pests and pathogens. However, there are different notions of ‘loss’, as well as sociocultural considerations, including social acceptability, which are often neglected in decision-making for restoration. 2. This paper explores concepts and meanings of ‘loss’, discusses sociocultural aspects and analyses social acceptability in relation to possible restoration routes for elm species in Great Britain (GB). 3. We identified different forms of ecological or species ‘loss’. For this paper, we recognise the following: Biological loss relates to biological extinction at varying scales. Functional loss refers to functional characteristics and traits of a species. Cultural loss refers to cultural connection, and societal loss refers to common utilisation and values. 4. Tree species such as field elm and wych elm have either radically transformed or have almost disappeared from large areas of GB since the 1960s, due to Dutch Elm Disease (DED). Biological presence continues, mainly in the form of small shrub-like trees, but functional, cultural and social loss continues through the decline of most large, freestanding elms. Some mature elms remain in refuge areas, especially in the north of Scotland where DED has not yet been recorded. 5. A range of restoration routes have been identified for elm in GB, from individual tree management or the creation of biosecure refugia, to the use of genetic technology. These options are each subject to different constraints, address ‘loss’ in diverse ways and face different levels of social acceptability, related in part to sociocultural connections. 6. We conclude that the following must be addressed to ensure socially acceptable routes to restoration: recognition of sociocultural considerations, trade-offs between public engagement and efficacy, absence of trust, lack of accessible information, evidence gaps, long-term funding and resources, and platforms for public dialogue. We emphasise the need for multiple notions of ‘loss’ and a shift to consideration of interlinked social, cultural and ecological regeneration as we forge new relationships and practices for tree health and sustainability.Peer reviewe
exoALMA. VI. Rotating under pressure : rotation curves, azimuthal velocity substructures, and pressure variations
Get PDFFunding: J.S., M.B., and D.F. have received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (PROTOPLANETS, grant agreement No. 101002188). J.S. has performed computations on the “Mesocentre SIGAMM” machine, hosted by Observatoire de la Cote d’Azur. A.J.W. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 101104656. Support for A.F.I. was provided by NASA through a NASA Hubble Fellowship, grant No. HST-HF2-51532.001-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. C.L. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 823823 (DUSTBUSTERS) and by the UK Science and Technology research Council (STFC) via the consolidated grant No. ST/W000997/1. P.C. acknowledges support by the Italian Ministero dell’Istruzione, Università e Ricerca, through the grant Progetti Premiali 2012—iALMA (CUP C52I13000140001) and by the ANID BASAL project FB210003. J.B. acknowledges support from NASA XRP grant No. 80NSSC23K1312. N.C. has received funding from the European Research Council (ERC) under the European Union Horizon Europe research and innovation program (grant agreement No. 101042275, project Stellar-MADE). S.F. is funded by the European Union (ERC, UNVEIL, 101076613), and acknowledges the financial contribution from PRIN-MUR 2022YP5ACE. M.F. is supported by a Grant-in-Aid from the Japan Society for the Promotion of Science (KAKENHI, grant No. JP22H01274). C.H. acknowledges support from NSF AAG grant No. 2407679. I.H. acknowledges a Research Training Program scholarship from the Australian Government. T.H. is supported by an Australian Government Research Training Program (RTP) Scholarship. J.D.I. acknowledges support from an STFC Ernest Rutherford Fellowship (grant No. ST/W004119/1) and a University Academic Fellowship from the University of Leeds. G.L. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 823823 (DUSTBUSTERS). F.M. has received funding from the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation program (grant agreement No. 101053020, project Dust2Planets). C.P. acknowledges Australian Research Council funding via grant Nos. FT170100040, DP18010423, DP220103767, and DP240103290. D.P. acknowledges Australian Research Council funding via grant Nos. DP18010423, DP220103767, and DP240103290. G.R. acknowledges funding from the Fondazione Cariplo, grant No. 2022-1217, and the European Research Council (ERC) under the European Union’s Horizon Europe Research & Innovation Programme under grant agreement No. 101039651 (DiscEvol). H.-W.Y. acknowledges support from the National Science and Technology Council (NSTC) in Taiwan through grant No. NSTC 113-2112-M-001-035- and from an Academia Sinica Career Development Award (grant No. AS-CDA-111-M03). G.W.F. acknowledges support from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 815559, MHDiscs). G.W.F. was granted access to the HPC resources of IDRIS under the allocation A0120402231 made by GENCI. T.C.Y. acknowledges support by a Grant-in-Aid for JSPS Fellows (grant No. JP23KJ1008). Support for B.Z. was provided by The Brinson Foundation.The bulk motion of the gas in protoplanetary disks around newborn stars is nearly Keplerian. By leveraging the high angular and spectral resolution of the Atacama Large Millimeter/submillimeter Array (ALMA), we can detect small-scale velocity perturbations in molecular line observations caused by local gas pressure variations in the disk, possibly induced by embedded protoplanets. This Letter presents the azimuthally averaged rotational velocity and its deviations from Keplerian rotation (δυϕ) for the exoALMA sample, as measured in the 12CO J = 3–2 and 13CO J = 3–2 emission lines. The rotation signatures show evidence for vertically stratified disks, in which 13CO rotates faster than 12CO due to a distinct thermal gas pressure gradient at their emitting heights. We find δυϕ substructures in the sample on both small (∼10 au) and large (∼100 au) radial scales, reaching deviations up to 15% from background Keplerian velocity in the most extreme cases. More than 75% of the rings and 80% of the gaps in the dust continuum emission resolved in δυϕ are colocated with gas pressure maxima and minima, respectively. Additionally, gas pressure substructures are observed far beyond the dust continuum emission. For the first time, we determined the gas pressure derivative at the midplane from observations, and found it to align well with the dust substructures within the given uncertainties. Based on our findings, we conclude that gas pressure variations are likely the dominant mechanism for ring and gap formation in the dust continuum.Peer reviewe
Leveraging alkylcobalt(IV) intermediates in cobalt-catalysed alkene hydrofunctionalisations
No full textAbstract redacte
The enigma of Gaia18cjb : a possible rare hybrid of FUor and EXor properties
Get PDFFunding: This work has been supported by the project PRIN’INAF 2019 “Spectroscopically Tracing the Disk Dispersal Evolution (STRADE)” and by the INAF Large Grant 2022 “YSOs Outflow, Disks and Accretion (YODA)”. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 716155 (SACCRED). We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team (https://gsaweb.ast.cam. ac.uk/alerts) This work is (partly) based on data obtained with the instrument EMIR, built by a Consortium led by the Instituto de Astrofísica de Canarias. EMIR was funded by GRANTECAN and the National Plan of Astronomy and Astrophysics of the Spanish Government. This work is (partly) based on data obtained at the Mount Suhora Observatory, Krakow Pedagogical University, Poland. This work has been supported by the Hungarian National Research, Development and Innovation Office grants OTKA K131508, OTKA K138962, the Élvonal KKP-143986 and KKP-137523 ‘SeismoLab’ grants of the Hungarian Research, Development and Innovation Office (NKFIH). We acknowledge support from the ESA PRODEX contract nr. 4000132054. KV, LK, ZN, and GM are supported by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences, KV is supported by the Bolyai+ grant ÚNKP22-5-ELTE-1093. Authors acknowledge the financial support of the AustrianHungarian Action Foundation (112öu1). LK is supported by the Hungarian National Research, Development and Innovation Office grant PD-134784. G.M. acknowledges support from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004141. This work is supported by the Polish MNiSW grant DIR/WK/2018/12 and the European Union’s Horizon 2020 research and innovation program under grant agreement No. 101004719 (OPTICON-RadioNet Pilot). Zs.M.Sz. acknowledges funding from a St Leonards scholarship from the University of St Andrews. BZs is supported by the ÚNKP-22-2 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. We acknowledge the Hungarian National Research, Development and Innovation Office grant OTKA FK 146023. FCSM received financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC Starting Grant “Chemtrip”, grant agreement No 949278). This work was also supported by the NKFIH excellence grant TKP2021-NKTA-64.Context . Gaia18cjb is one of the Gaia-alerted eruptive young star candidates that has been experiencing a slow and strong brightening during the last 13 years, similarly to some FU Orionis-type objects. Aims . The aim of this work is to derive the young stellar nature of Gaia18cjb and determine its physical and accretion properties to classify its variability. Methods . We conducted monitoring observations using multi-filter optical and near-infrared (NIR) photometry, as well as NIR spectroscopy. We present an analysis of pre-outburst and outburst optical and IR light curves, color-magnitude diagrams in different bands, the detection of NIR spectral lines, and estimates of both stellar and accretion parameters during the burst. Results . The optical light curve shows an unusually long (over 8 years) brightening event of 5 mag in the last 13 years, before reaching a plateau indicating that the burst is still ongoing, suggesting a FU Orionis-like (FUor-like) nature. The same outburst is less strong in the IR light curves. The NIR spectra, obtained during the outburst, exhibit emission lines typical of highly accreting low-intermediate mass young stars with typical EX Lupi-type (EXor) features. The spectral index of Gaia18cjb SED classifies it as a Class I in the pre-burst stage and a flat-spectrum young stellar object (YSO) during the burst. Conclusions . Gaia18cjb is an eruptive YSO that exhibits FUor-like photometric features (in terms of brightening amplitude and length of the burst) as well as EXor-like spectroscopic features and accretion rate. Its nature appears similar to that of V350 Cep and V1647 Ori, which have been classified as objects in between FUors and EXors.Peer reviewe
Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b
Get PDFFunding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the UK. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. CHEOPS data analysed in this article will be made available in the CHEOPS mission archive (https://cheops.unige.ch/archive_browser/). This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 through the research grants UIDB/04434/2020, UIDP/04434/2020, 2022.06962.PTDC. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. V.Si., T.Zi., L.Bo., V.Na., I.Pa., G.Pi., R.Ra., and G.Sc. acknowledge support from CHEOPS ASI-INAF agreement no. 2019-29-HH.0. T.Wi. acknowledges support from the UKSA and the University of Warwick. L.Ca. and C.He. acknowledge support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project FOUR ACES. grant agreement No 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). D.E. acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. PM acknowledges support from STFC research grant number ST/M001040/1. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. S.G.S. acknowledge support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). A.Br. was supported by the SNSA. Y.Al. acknowledges support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. R.Al., D.Ba., E.Pa., and I.Ri. acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 and the ERDF “A way of making Europe” through projects PID2019-107061GB-C61, PID2019-107061GB-C66, PID2021-125627OB-C31, and PID2021-125627OB-C32, from the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), from the Centre of Excellence “María de Maeztu” award to the Institut de Ciències de l’Espai (CEX2020-001058-M), and from the Generalitat de Catalunya/CERCA programme. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. C.Br. and A.Si. acknowledge support from the Swiss Space Office through the ESA PRODEX program. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. This project was supported by the CNES. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseousor rocky? Unveiling the nature of small worlds”. M.G. is an F.R.S.-FNRS Senior Research Associate. M.N.G. is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. M.N.G. does not relay proprietary information between the GO and Guaranteed Time Observation (GTO) Programmes, and does not decide on the definition and target selection of the GTO Programme. S.H. gratefully acknowledges CNES funding through the grant 837319. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. This work was granted access to the HPC resources of MesoPSL financed by the Région Île de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). N.C.Sa. acknowledges funding by the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. Gy.M.Sz. acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Experiment Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S-FNRS Research Associate. N.A.W. acknowledges UKSA grant ST/R004838/1.Context . WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve. Aims . We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods . We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves. Results . WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30◦, and a width of ∼20◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy. Conclusions . In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.Peer reviewe
Limited decrease of Southern Ocean sulfur productivity across the penultimate termination
Get PDFFunding: H.F. gratefully acknowledges the financial support by the Swiss National Science Foundation (grant nos. 200020_172506 and 200020B_200328) and sabbatical support by the University of St Andrews in 2022. This work is a contribution to the European Project for Ice Coring in Antarctica (EPICA), a joint European Science Foundation/European Commission scientific programme, funded by the EU (EPICA-MIS) and by national contributions from Belgium, Denmark, France, Germany, Italy, the Netherlands, Norway, Sweden, Switzerland and the UK. The main logistic support was provided by Institut Polaire Français Paul-Émile Victor and Programma Nazionale di Ricerche in Antartide (at Dome C) and Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (at Dronning Maud Land). This is EPICA publication no. 323.Productivity in the Pleistocene glacial Southern Ocean was probably enhanced owing to iron fertilization by aeolian dust. Marine sediments indicate such an increase north of the modern Antarctic Polar Front but reduced biogenic activity south of it. However, quantitative estimates for the integrated net effect are difficult to obtain. Here we use the SO42− isotopic composition and other geochemical ice core records from the Atlantic sector of the Southern Ocean to reconstruct net changes in integrated biogenic sulfur productivity in the surface ocean over the penultimate glacial termination. We show that biogenic SO42− aerosol contributes 58% and 85% to the sulfate budget in Dronning Maud Land during glacial and interglacial times, respectively, and that biogenic sulfate is derived predominately from the seasonal sea ice zone. Using our quantitative reconstruction of biogenic aerosol production in the Southern Ocean source region, we show that the average biogenic sulfate production integrated over the Atlantic sector was 16% higher in the penultimate glacial 137,000–153,000 years ago compared with the later Last Interglacial 120,000–125,000 years ago. An intermittent decrease in productivity observed during early peak interglacial warming suggests that a reduction in the seasonal sea ice zone may disrupt Southern Ocean ecosystems.Peer reviewe
Access Repository Dashboard
Do you manage St Andrews Research Repository? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!