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The nonlinear evolution of two surface quasi-geostrophic vortices
Get PDFFunding: This work was supported by Ecole Normale Superieure de Rennes [PhD grant to Armand Vic].We investigate numerically the evolution of a baroclinic vortex in a two-level surface quasi-geostrophic model. The vortex is composed of two circular patches of uniform buoyancy, one located at each level. We vary the vortex radii, the magnitude of buoyancy, and the vertical distance between the two levels. We also study different radial profiles of buoyancy for each vortex. This paper considers two main situations: firstly, initially columnar vortices with like-signed buoyancies. These vortices are contra-rotating, are linearly unstable and may break. Secondly, we consider initially tilted vortices with opposite-signed buoyancies, which may align vertically. Numerical experiments show that (1) identical contra-rotating vortices break into hetons when initially perturbed by low azimuthal modes; (2) unstable, vertically asymmetric, contra-rotating vortices can stabilise nonlinearly more often than vertically symmetric ones, and can form quasi-steady baroclinic tripoles; (3) co-rotating vortices can align when the two levels are close to each other vertically, and when the vortices are initially horizontally distant from each other by less than three radii; (4) for initially more distant vortices, two such vortices rotate around the plane center; (5) in all cases, the vortex boundaries are disturbed by Rossby waves. These results compare favorably to earlier results with internal quasi-geostrophic vortices. Further modelling efforts may extend the present study to fully three dimensional ocean dynamics.Peer reviewe
Eating in a losing cause : limited benefit of modified macronutrient consumption following infection in the oriental cockroach Blatta orientalis
Get PDFOpen Access funding enabled and organized by Projekt DEAL. S.H. was supported by the Chinese Scholarship Council and D.P.M. was supported by a seed-funding Grant provided by the Freie Universität Berlin and grant MC 436/6-1 from the Deutsche Forschungsgemeinschaft (DFG).Background Host–pathogen interactions can lead to dramatic changes in host feeding behaviour. One aspect of this includes self-medication, where infected individuals consume substances such as toxins or alter their macronutrient consumption to enhance immune competence. Another widely adopted animal response to infection is illness-induced anorexia, which is thought to assist host immunity directly or by limiting the nutritional resources available to pathogens. Here, we recorded macronutrient preferences of the global pest cockroach, Blatta orientalis to investigate how shifts in host macronutrient dietary preference and quantity of carbohydrate (C) and protein (P) interact with immunity following bacterial infection. Results We find that B. orientalis avoids diets enriched for P under normal conditions, and that high P diets reduce cockroach survival in the long term. However, following bacterial challenge, cockroaches significantly reduced their overall nutrient intake, particularly of carbohydrates, and increased the relative ratio of protein (P:C) consumed. Surprisingly, these behavioural shifts had a limited effect on cockroach immunity and survival, with minor changes to immune protein abundance and antimicrobial activity between individuals placed on different diets, regardless of infection status. Conclusions We show that cockroach feeding behaviour can be modulated by a pathogen, resulting in an illness-induced anorexia-like feeding response and a shift from a C-enriched to a more P:C equal diet. However, our results also indicate that such responses do not provide significant immune protection in B. orientalis, suggesting that the host’s dietary shift might also result from random rather than directed behaviour. The lack of an apparent benefit of the shift in feeding behaviour highlights a possible reduced importance of diet in immune regulation in these invasive animals, although further investigations employing pathogens with alternative infection strategies are warranted.Peer reviewe
Review 1: Laboratory validation of a simplified DNA extraction protocol followed by a portable qPCR detection of M. tuberculosis DNA suitable for point of care settings
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Identification of the top TESS objects of interest for atmospheric characterization of transiting exoplanets with JWST
Get PDFFunding: Funding for the TESS mission is provided by NASA's Science Mission Directorate. This work makes use of observations from the LCOGT network. Part of the LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by NSF. This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial support by JSPS KAKENHI (grant No. JP18H05439) and JST PRESTO (grant No. JPMJPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. This paper makes use of data from the MEarth Project, which is a collaboration between Harvard University and the Smithsonian Astrophysical Observatory. The MEarth Project acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering, the National Science Foundation under grant Nos. AST-0807690, AST-1109468, AST-1616624 and AST-1004488 (Alan T. Waterman Award), the National Aeronautics and Space Administration under grant No. 80NSSC18K0476 issued through the XRP Program, and the John Templeton Foundation. C.M. would like to gratefully acknowledge the entire Dragonfly Telephoto Array team, and Bob Abraham in particular, for allowing their telescope bright time to be put to use observing exoplanets. B.J.H. acknowledges support from the Future Investigators in NASA Earth and Space Science and Technology (FINESST) program (grant No. 80NSSC20K1551) and support by NASA under grant No. 80GSFC21M0002. K.A.C. and C.N.W. acknowledge support from the TESS mission via subaward s3449 from MIT. D.R.C. and C.A.C. acknowledge support from NASA through the XRP grant No. 18-2XRP18_2-0007. C.A.C. acknowledges that this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). S.Z. and A.B. acknowledge support from the Israel Ministry of Science and Technology (grant No. 3-18143). The research leading to these results has received funding from the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant No. PDR T.0120.21. The postdoctoral fellowship of K.B. is funded by F.R.S.-FNRS grant No. T.0109.20 and by the Francqui Foundation. H.P.O.'s contribution has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grant Nos. 51NF40_182901 and 51NF40_205606. F.J.P. acknowledges financial support from the grant No. CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033. A.J. acknowledges support from ANID—Millennium Science Initiative—ICN12_009 and from FONDECYT project 1210718. Z.L.D. acknowledges the MIT Presidential Fellowship and that this material is based upon work supported by the National Science Foundation Graduate Research Fellowship under grant No. 1745302. P.R. acknowledges support from the National Science Foundation grant No. 1952545. This work is partly supported by JSPS KAKENHI grant Nos. JP17H04574, JP18H05439, JP21K20376; JST CREST grant No. JPMJCR1761; and Astrobiology Center SATELLITE Research project AB022006. This publication benefits from the support of the French Community of Belgium in the context of the FRIA Doctoral Grant awarded to M.T. D.D. acknowledges support from TESS Guest Investigator Program grant Nos. 80NSSC22K1353, 80NSSC22K0185, and 80NSSC23K0769. A.B. acknowledges the support of M.V. Lomonosov Moscow State University Program of Development. T.D. was supported in part by the McDonnell Center for the Space Sciences. V.K. acknowledges support from the youth scientific laboratory project, topic FEUZ-2020-0038.JWST has ushered in an era of unprecedented ability to characterize exoplanetary atmospheres. While there are over 5000 confirmed planets, more than 4000 Transiting Exoplanet Survey Satellite (TESS) planet candidates are still unconfirmed and many of the best planets for atmospheric characterization may remain to be identified. We present a sample of TESS planets and planet candidates that we identify as “best-in-class” for transmission and emission spectroscopy with JWST. These targets are sorted into bins across equilibrium temperature Teq and planetary radius Rp and are ranked by a transmission and an emission spectroscopy metric (TSM and ESM, respectively) within each bin. We perform cuts for expected signal size and stellar brightness to remove suboptimal targets for JWST. Of the 194 targets in the resulting sample, 103 are unconfirmed TESS planet candidates, also known as TESS Objects of Interest (TOIs). We perform vetting and statistical validation analyses on these 103 targets to determine which are likely planets and which are likely false positives, incorporating ground-based follow-up from the TESS Follow-up Observation Program to aid the vetting and validation process. We statistically validate 18 TOIs, marginally validate 31 TOIs to varying levels of confidence, deem 29 TOIs likely false positives, and leave the dispositions for four TOIs as inconclusive. Twenty-one of the 103 TOIs were confirmed independently over the course of our analysis. We intend for this work to serve as a community resource and motivate formal confirmation and mass measurements of each validated planet. We encourage more detailed analysis of individual targets by the community.Peer reviewe
Phosphirenium ions as masked phosphenium catalysts : mechanistic evaluation and application in synthesis
Get PDFThe EPSRC is thanked for funding. S.E.N. thanks Heriot Watt University for the award of a James Watt scholarship.The utilization of phosphirenium ions is presented; optimized and broadened three-membered ring construction is described together with the use of these ions as efficient pre-catalysts for metal-free carbonyl reduction with silanes. Full characterization of the phosphirenium ions is presented, and initial experimental and computational mechanistic studies indicate that these act as a "masked phosphenium"source that is accessed via ring opening. Catalysis proceeds via associative transfer of {Ph2P+} to a carbonyl nucleophile, Hâ'SiR3 bond addition over the C=O group, and associative displacement of the product by a further equivalent of the carbonyl substrate, which completes the catalytic cycle. A competing off-cycle process leading to vinyl phosphine formation is detailed for the hydrosilylation of benzophenone for which an inverse order in [silane] is observed. Experimentally, the formation of side products, including off-cycle vinyl phosphine, is favored by electrondonating substituents on the phosphirenium cation, while catalytic hydrosilylation is promoted by electron-withdrawing substituents. These observations are rationalized in parallel computational studies.Peer reviewe
MUSE observations of small-scale heating events
Get PDFFunding: The research leading to these results has received funding from the UK Science and Technology Facilities Council (consolidated grant ST/W001195/1). The research leading to these results has received funding from a Royal Society Wolfson Fellowship (RSWF/FT/180005). IDM received funding from the Research Council of Norway through its Centres of Excellence scheme, project number 262622. PT was supported by contract 4105785828 (MUSE) to the Smithsonian Astrophysical Observatory and by NASA grant 80NSSC20K1272.Constraining the processes that drive coronal heating from observations is a difficult task due to the complexity of the solar atmosphere. As upcoming missions such as MUSE will provide coronal observations with unprecedented spatial and temporal resolution, numerical simulations are becoming increasingly realistic. Despite the availability of synthetic observations from numerical models, line-of-sight effects and the complexity of the magnetic topology in a realistic setup still complicate the prediction of signatures for specific heating processes. 3D MHD simulations have shown that a significant part of the Poynting flux injected into the solar atmosphere is carried by small-scale motions, such as vortices driven by rotational flows inside intergranular lanes. MHD waves excited by these vortices have been suggested to play an important role in the energy transfer between different atmospheric layers. Using synthetic spectroscopic data generated from a coronal loop model incorporating realistic driving by magnetoconvection, we study whether signatures of energy transport by vortices and eventual dissipation can be identified with future missions such as MUSE.Peer reviewe
A conceptual framework for Emergent Language Learner Autonomy - a complexity perspective for action research
Get PDFPurpose This paper addresses inconsistencies in how language learner autonomy has been understood. A novel conceptual framework of Emergent Language Learner Autonomy (ELLA) is proposed, reconceiving it within Complex Dynamic Systems Theory. ELLA aims at a comprehensive conceptual understanding of language learner autonomy, an explanatory foundation for enhancing empowerment of educational stakeholders. Design/methodology/approach The paper offers a review of the conceptual literature on language learner autonomy and explores intersections with operationalisation and measurement with Action Research. Findings The paper identifies areas in which reductionist theoretical models are unsuited to describing language learner autonomy. Complex Dynamic Systems Theory is found to be a better fit. The proposed conceptual framework is modelled on Hopfield networks: series of dynamic, transitional relations between temporary and final states through which multilateral changes propagate. Language learner autonomy arises under conducive conditions at inflection points as an epiphenomenon, underscoring the need for holistic epistemological reorientation in research and practice. Originality This paper puts forward an innovative conceptual framework for understanding language learner autonomy as an emergent phenomenon. It contributes to the wider literature by addressing the need to resolve conceptual inconsistencies that undermine much research and practice. The novel framework informs compelling arguments for Action Research by practitioners from a complexity perspective – embracing adaptive, dynamic, non-linear research designs. The framework also emphasises the need for practitioners to adopt exploratory approaches to fostering language learner autonomy in their context.Peer reviewe
Chemical scissor-enabled synthesis of Ti3C2Tx MXene nanowires for selective oxygen reduction to hydrogen peroxide
Get PDFThis work was financially supported by National Natural Science Foundation of China (21975030).Transition metal carbides, especially Ti3C2Tx, display appealing prospects in the field of energy conversion and storage due to the unique combination of good conductivity and abundant functional groups. The physical structure as well as surface terminations of Ti3C2Tx have significant impact on its properties when scaling down from 3D bulk to 2D sheets. However, moving toward 1D nanowire remains a great challenge because of the absence of anisotropic skeleton in Ti3C2Tx. Herein, we demonstrate a facile strategy to convert Ti3C2Tx nanosheets into crosslinked Ti3C2Tx nanowires in hybrid alkaline solutions. The experimental results and theoretical calculation reveal that both OH− and O2 play important roles in the controllable cutting of Ti3C2Tx nanosheets into nanowires. Compared to Ti3C2Tx nanosheets, crosslinked Ti3C2Tx nanowires expose much higher density of active sites at edges and surfaces, making them ideal catalysts for oxygen reduction reaction (ORR). Unexpectedly, Ti3C2Tx nanowires can selectively reduce oxygen through a 2e− pathway to hydrogen peroxide. The structural modulation of MXene opens a new avenue toward improved performance in emerging application fields.Peer reviewe
Mini-AFTERc: a controlled pilot trial of a nurse-led psychological intervention for fear of breast cancer recurrence
Get PDFFunding: The study was funded by the Chief Scientist Ofce (CSO), which is part of the Scottish Government Health Directorates (reference: HIPS/17/57).Objectives To determine the feasibility and acceptability of implementing the Mini-AFTERc intervention. Design Non-randomised cluster-controlled pilot trial. Setting Four NHS out-patient breast cancer centres in Scotland. Participants Ninety-two women who had successfully completed primary treatment for breast cancer were screened for moderate levels of fear of cancer recurrence (FCR). Forty-five were eligible (17 intervention and 28 control) and 34 completed 3-month follow-up (15 intervention and 21 control). Intervention Mini-AFTERc, a single brief (30 min) structured telephone discussion with a specialist breast cancer nurse (SBCN) trained to target the antecedents of FCR. Outcomes Feasibility and acceptability of Mini-AFTERc and the study design were assessed via recruitment, consent, retention rates, patient outcomes (measured at baseline, 2, 4, and 12 weeks), and post-study interviews with participants and SBCNs, which were guided by Normalisation Process Theory. Results Mini-AFTERc was acceptable to patients and SBCNs. SBCNs believe the implementation of Mini-AFTERc to be feasible and an extension of discussions that already happen routinely. SBCNs believe delivery, however, at the scale required would be challenging given current competing demands for their time. Recruitment was impacted by variability in the follow-up practices of cancer centres and COVID-19 lockdown. Consent and follow-up procedures worked well, and retention rates were high. Conclusions The study provided invaluable information about the potential challenges and solutions for testing the Mini-AFTERc intervention more widely where limiting high FCR levels is an important goal following recovery from primary breast cancer treatment.Peer reviewe
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