1,892 research outputs found
A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars
The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is
indicative of very energetic, transient phenomena, associated with energy
release via magnetic reconnection. We present a uniform, large-scale survey of
X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its
associated data products provide an excellent basis for a comprehensive and
sensitive survey of stellar flares - both from targeted active stars and from
those observed serendipitously in the half-degree diameter field-of-view of
each observation. The 2XMM Catalogue and the associated time-series
(`light-curve') data products have been used as the basis for a survey of X-ray
flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have
generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray
light-curves. Where available, we have compared XMM OM UV/optical data with the
X-ray light-curves. Our sample contains ~130 flares with well-observed
profiles; they originate from ~70 stars. The flares range in duration from ~1e3
to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray
luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to
~1e35 erg. Most of the ~30 serendipitously-observed stars have little
previously reported information. The hardness-ratio plots clearly illustrate
the spectral (and hence inferred temperature) variations characteristic of many
flares, and provide an easily accessible overview of the data. We present flare
frequency distributions from both target and serendipitous observations. The
latter provide an unbiased (with respect to stellar activity) study of flare
energetics; in addition, they allow us to predict numbers of stellar flares
that may be detected in future X-ray wide-field surveys. The serendipitous
sample demonstrates the need for care when calculating flaring rates.Comment: 26 pages, 24 figures. Additional tables and figures available as 4
ancillary files. To be published in Astronomy and Astrophysic
OA04.01. Effects of relaxation response intervention on endogenous progenitor cells in a hypertensive population
Recent Southern Ocean warming and freshening driven by greenhouse gas emissions and ozone depletion
Nunalleq, Stories from the Village of Our Ancestors:Co-designing a multivocal educational resource based on an archaeological excavation
This work was funded by the UK-based Arts and Humanities Research Council through grants (AH/K006029/1) and (AH/R014523/1), a University of Aberdeen IKEC Award with additional support for travel and subsistence from the University of Dundee, DJCAD Research Committee RS2 project funding. Thank you to the many people who contributed their support, knowledge, feedback, voices and faces throughout the project, this list includes members of the local community, colleagues, specialists, students, and volunteers. If we have missed out any names we apologize but know that your help was appreciated. Jimmy Anaver, John Anderson, Alice Bailey, Kieran Baxter, Pauline Beebe, Ellinor Berggren, Dawn Biddison, Joshua Branstetter, Brendan Body, Lise Bos, Michael Broderick, Sarah Brown, Crystal Carter, Joseph Carter, Lucy Carter, Sally Carter, Ben Charles, Mary Church, Willard Church, Daniele Clementi, Annie Cleveland, Emily Cleveland, Joshua Cleveland, Aron Crowell, Neil Curtis, Angie Demma, Annie Don, Julia Farley, Veronique Forbes, Patti Fredericks, Tricia Gillam, Sean Gleason, Sven Haakanson, Cheryl Heitman, Grace Hill, Diana Hunter, Joel Isaak, Warren Jones, Stephan Jones, Ana Jorge, Solveig Junglas, Melia Knecht, Rick Knecht, Erika Larsen, Paul Ledger, Jonathan Lim Soon, Amber Lincoln, Steve Luke, Francis Lukezic, Eva Malvich, Pauline Matthews, Roy Mark, Edouard Masson-MacLean, Julie Masson-MacLean, Mhairi Maxwell, Chuna Mcintyre, Drew Michael, Amanda Mina, Anna Mossolova, Carl Nicolai Jr, Chris Niskanen, Molly Odell, Tom Paxton, Lauren Phillips, Lucy Qin, Charlie Roberts, Chris Rowe, Rufus Rowe,Chris Rowland, John Rundall, Melissa Shaginoff, Monica Shah, Anna Sloan, Darryl Small Jr, John Smith, Mike Smith, Joey Sparaga, Hannah Strehlau, Dora Strunk, Larissa Strunk, Lonny Strunk, Larry Strunk, Robbie Strunk, Sandra Toloczko, Richard Vanderhoek, the Qanirtuuq Incorporated Board, the Quinhagak Dance Group and the staff at Kuinerrarmiut Elitnaurviat. We also extend our thanks to three anonymous reviewers for their valuable comments on our paper.Peer reviewedPublisher PD
Back to the future: Using long-term observational and paleo-proxy reconstructions to improve model projections of antarctic climate
Quantitative estimates of future Antarctic climate change are derived from numerical global climate models. Evaluation of the reliability of climate model projections involves many lines of evidence on past performance combined with knowledge of the processes that need to be represented. Routine model evaluation is mainly based on the modern observational period, which started with the establishment of a network of Antarctic weather stations in 1957/58. This period is too short to evaluate many fundamental aspects of the Antarctic and Southern Ocean climate system, such as decadal-to-century time-scale climate variability and trends. To help address this gap, we present a new evaluation of potential ways in which long-term observational and paleo-proxy reconstructions may be used, with a particular focus on improving projections. A wide range of data sources and time periods is included, ranging from ship observations of the early 20th century to ice core records spanning hundreds to hundreds of thousands of years to sediment records dating back 34 million years. We conclude that paleo-proxy records and long-term observational datasets are an underused resource in terms of strategies for improving Antarctic climate projections for the 21st century and beyond. We identify priorities and suggest next steps to addressing this.The Antarctic Climate Change in the 21st Century (AntClim21) Scientific Research Programme of the
Scientific Committee on Antarctic Research are thanked for supporting the international scientific workshop at
which the writing of this manuscript was initiated. This is a contribution to the PAGES 2k Network (through the
CLIVASH 2k project). NJA acknowledges support by the Australian Research Council through a Future Fellowship
(FT160100029) and the Centre of Excellence for Climate Extremes (CE170100023). SJP was supported under
the Australian Research Council’s Special Research Initiative for the Antarctic Gateway Partnership (Project ID
SR140300001). JMJ acknowledges support from the Leverhulme Trust through a Research Fellowship (RF-2018-183).
FC acknowledges support from the PNRA national Italian projects PNRA16_00016, “WHISPERS” and project
PNRA_00002, “ANTIPODE”. TJB, LS, and ERT were supported by the Natural Environment Research Council
(NERC) as part of the British Antarctic Survey Polar Science for Planet Earth Programme. TJB additionally
acknowledges support for this work as a contribution to the NERC grant NE/N01829X/1. IW thanks FAPESP
2015/50686-1, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) Finance Code 001
and CNPq 300970/2018-8, CNPq INCT Criosfera 704222/200
Ferredoxin containing bacteriocins suggest a novel mechanism of iron uptake in <i>Pectobacterium spp</i>
In order to kill competing strains of the same or closely related bacterial species, many bacteria produce potent narrow-spectrum protein antibiotics known as bacteriocins. Two sequenced strains of the phytopathogenic bacterium <i>Pectobacterium carotovorum</i> carry genes encoding putative bacteriocins which have seemingly evolved through a recombination event to encode proteins containing an N-terminal domain with extensive similarity to a [2Fe-2S] plant ferredoxin and a C-terminal colicin M-like catalytic domain. In this work, we show that these genes encode active bacteriocins, pectocin M1 and M2, which target strains of <i>Pectobacterium carotovorum</i> and <i>Pectobacterium atrosepticum</i> with increased potency under iron limiting conditions. The activity of pectocin M1 and M2 can be inhibited by the addition of spinach ferredoxin, indicating that the ferredoxin domain of these proteins acts as a receptor binding domain. This effect is not observed with the mammalian ferredoxin protein adrenodoxin, indicating that <i>Pectobacterium spp.</i> carries a specific receptor for plant ferredoxins and that these plant pathogens may acquire iron from the host through the uptake of ferredoxin. In further support of this hypothesis we show that the growth of strains of <i>Pectobacterium carotovorum</i> and <i>atrosepticum</i> that are not sensitive to the cytotoxic effects of pectocin M1 is enhanced in the presence of pectocin M1 and M2 under iron limiting conditions. A similar growth enhancement under iron limiting conditions is observed with spinach ferrodoxin, but not with adrenodoxin. Our data indicate that pectocin M1 and M2 have evolved to parasitise an existing iron uptake pathway by using a ferredoxin-containing receptor binding domain as a Trojan horse to gain entry into susceptible cells
Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity
Acknowledgments The authors gratefully acknowledge Sylvia Stephen, Jean Bryce, Nina Lamza, Karen Taylor, Melanie Hudson, Kat Niblock, Ewa Wojtaczka, Aimee Sutherland, David Bremner, Claire Kidd, and Alicia Bryce at the Human Nutrition Unit of the Rowett Institute for their support in meal preparation and participant assessment. The authors acknowledge the contribution of NIHR Core Biochemistry Assay Laboratory, Cambridge Biomedical Research Centre (gut hormone analysis), and Loek Wouters at Maastricht University, Netherlands (DLW analysis). The authors also gratefully acknowledge Claus-Dieter Mayer for statistical analysis and modeling of the gastric emptying data. The authors gratefully acknowledge funding from the Medical Research Council (grant MR/P012205/1, The Big Breakfast study). A.M.J., P.J.M., G.W.H., and J.A.N.F. also acknowledge funding support from the Scottish Government, Rural and Environment Science and Analytical Services Division. Author contributions Conceptualization, design, and funding acquisition, A.M.J., P.J.M., and J.D.J.; investigation, L.C.R.-C. and C.L.F.; DLW analysis and modeling, K.R.W.; statistical analysis, G.W.H. and J.A.N.F.; writing – original draft, L.C.R.-C. and A.M.J.; writing – review & editing, all authors.Peer reviewedPublisher PD
Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity
Acknowledgments The authors gratefully acknowledge Sylvia Stephen, Jean Bryce, Nina Lamza, Karen Taylor, Melanie Hudson, Kat Niblock, Ewa Wojtaczka, Aimee Sutherland, David Bremner, Claire Kidd, and Alicia Bryce at the Human Nutrition Unit of the Rowett Institute for their support in meal preparation and participant assessment. The authors acknowledge the contribution of NIHR Core Biochemistry Assay Laboratory, Cambridge Biomedical Research Centre (gut hormone analysis), and Loek Wouters at Maastricht University, Netherlands (DLW analysis). The authors also gratefully acknowledge Claus-Dieter Mayer for statistical analysis and modeling of the gastric emptying data. The authors gratefully acknowledge funding from the Medical Research Council (grant MR/P012205/1, The Big Breakfast study). A.M.J., P.J.M., G.W.H., and J.A.N.F. also acknowledge funding support from the Scottish Government, Rural and Environment Science and Analytical Services Division.Peer reviewedPublisher PD
A 'Performative' Social Movement: The Emergence of Collective Contentions within Collaborative Governance
The enmeshment of urban movements in networks of collaborative governance has been characterised as a process of co-option in which previously disruptive contentions are absorbed by regimes and reproduced in ways that do not threaten the stability of power relations. Applying a theoretical framework drawn from feminist philosopher Judith Butler this paper directs attention to the development of collective oppositional identities that remain embedded in conventional political processes. In a case study of the English tenants' movement, it investigates the potential of regulatory discourses that draw on market theories of performative voice to offer the collectivising narratives and belief in change that can generate the emotional identification of a social movement. The paper originates the concept of the ‘performative social movement’ to denote the contentious claims that continue to emerge from urban movements that otherwise appear quiescent
An ∼140-kb Deletion Associated with Feline Spinal Muscular Atrophy Implies an Essential LIX1 Function for Motor Neuron Survival
The leading genetic cause of infant mortality is spinal muscular atrophy (SMA), a clinically and genetically heterogeneous group of disorders. Previously we described a domestic cat model of autosomal recessive, juvenile-onset SMA similar to human SMA type III. Here we report results of a whole-genome scan for linkage in the feline SMA pedigree using recently developed species-specific and comparative mapping resources. We identified a novel SMA gene candidate, LIX1, in an ~140-kb deletion on feline chromosome A1q in a region of conserved synteny to human chromosome 5q15. Though LIX1 function is unknown, the predicted secondary structure is compatible with a role in RNA metabolism. LIX1 expression is largely restricted to the central nervous system, primarily in spinal motor neurons, thus offering explanation of the tissue restriction of pathology in feline SMA. An exon sequence screen of 25 human SMA cases, not otherwise explicable by mutations at the SMN1 locus, failed to identify comparable LIX1 mutations. Nonetheless, a LIX1-associated etiology in feline SMA implicates a previously undetected mechanism of motor neuron maintenance and mandates consideration of LIX1 as a candidate gene in human SMA when SMN1 mutations are not found
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