8 research outputs found
Western Arctic Ocean temperature variability during the last 8000 years
No full textAuthor Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L24602, doi:10.1029/2011GL049714.We reconstructed subsurface (∼200–400 m) ocean temperature and sea-ice cover in the Canada Basin, western Arctic Ocean from foraminiferal δ18O, ostracode Mg/Ca ratios, and dinocyst assemblages from two sediment core records covering the last 8000 years. Results show mean temperature varied from −1 to 0.5°C and −0.5 to 1.5°C at 203 and 369 m water depths, respectively. Centennial-scale warm periods in subsurface temperature records correspond to reductions in summer sea-ice cover inferred from dinocyst assemblages around 6.5 ka, 3.5 ka, 1.8 ka and during the 15th century Common Era. These changes may reflect centennial changes in the temperature and/or strength of inflowing Atlantic Layer water originating in the eastern Arctic Ocean. By comparison, the 0.5 to 0.7°C warm temperature anomaly identified in oceanographic records from the Atlantic Layer of the Canada Basin exceeded reconstructed Atlantic Layer temperatures for the last 1200 years by about 0.5°C.J.R.F., T.M.C., and R.C.T. thank support by USGS Global Change
Program, G.S.D. thanks support from the USGS Global Change Program
and the NSF Office of Polar Programs, A.d.V. thanks support by Fond
québécois de la recherché sur la nature et les technologies (FQRNT) and
the Ministere du Développement économique, innovation et exportation
(MDEIE) of Quebec.2012-06-1
Phylogenomics Reveals Ancient Gene Tree Discordance in the Amphibian Tree of Life
No full textThe Author(s) 2020. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. Molecular phylogenies have yielded strong support for many parts of the amphibian Tree of Life, but poor support for the resolution of deeper nodes, including relationships among families and orders. To clarify these relationships, we provide a phylogenomic perspective on amphibian relationships by developing a taxon-specific Anchored Hybrid Enrichment protocol targeting hundreds of conserved exons which are effective across the class. After obtaining data from 220 loci for 286 species (representing 94% of the families and 44% of the genera), we estimate a phylogeny for extant amphibians and identify gene tree-species tree conflict across the deepest branches of the amphibian phylogeny. We perform locus-by-locus genealogical interrogation of alternative topological hypotheses for amphibian monophyly, focusing on interordinal relationships. We find that phylogenetic signal deep in the amphibian phylogeny varies greatly across loci in a manner that is consistent with incomplete lineage sorting in the ancestral lineage of extant amphibians. Our results overwhelmingly support amphibian monophyly and a sister relationship between frogs and salamanders, consistent with the Batrachia hypothesis. Species tree analyses converge on a small set of topological hypotheses for the relationships among extant amphibian families. These results clarify several contentious portions of the amphibian Tree of Life, which in conjunction with a set of vetted fossil calibrations, support a surprisingly younger timescale for crown and ordinal amphibian diversification than previously reported. More broadly, our study provides insight into the sources, magnitudes, and heterogeneity of support across loci in phylogenomic data sets.[AIC; Amphibia; Batrachia; Phylogeny; gene tree-species tree discordance; genomics; information theory.].This work was supported by grants from a graduate student research award from the Society of Systematic Biologists and the University of Kentucky G.F. Ribble Endowment (to P.M.H.), by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/BEX 2806/09-6 to P.L.V.P.), and by the National Science Foundation (DEB-0949532 and DEB-1355000 to D.W.W., DEB-1120516 to E.M.L., IIP-1313554 to A.R.L. and E.M.L, DEB-1355071 to J.M.B., DEB-1441719 to R.A.P., DEB-1311442 to P.L.V.P., DEB-1354506 to R.C.T., DEB-1021247 to E.P. and C.J.R., DEB-1021299 to K.M. Kjer, and DEB-1257610, DEB-0641023, DEB-0423286, and DEB-9984496 to C.J.R.), and the Australian Research Council (DP120104146 to J.S.K. and S.C.D.). S.R.R. thanks SENESCYT (Arca de Noé Initiative; SRR and O. Torres-Carvajal principal investigators) for funding for tissue collection. J.L. was supported by the Systematics Association and the Linnean Society Systematics Research Fund. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program (DGE-3048109801 to P.M.H.) and by the National Science Foundation-supported National Center for Supercomputing Applications Blue Waters Graduate Research Fellowship Program (under Grant No. 0725070, subaward 15836, to P.M.H.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
The correlation between reading and mathematics ability at age twelve has a substantial genetic component.
No full textDissecting how genetic and environmental influences impact on learning is helpful for maximizing numeracy and literacy. Here we show, using twin and genome-wide analysis, that there is a substantial genetic component to children's ability in reading and mathematics, and estimate that around one half of the observed correlation in these traits is due to shared genetic effects (so-called Generalist Genes). Thus, our results highlight the potential role of the learning environment in contributing to differences in a child's cognitive abilities at age twelve
Lapped joints in reinforced concrete
No full textThis thesis is concerned with an experimental investigation of the behaviour of lapped joints in reinforced concrete. A review of existing literature highlights the need to establish the longitudinal strain distribution along lap joints. This has been achieved experimentally, with detailed strain measurements being taken using a technique of internally gauging the reinforcing rods. In some specimens, strain concentration gauges were installed at the tip of the lap to permit the acquisition of particularly localised information. Computer programs were developed to process the substantial amounts of data generated during the course of each test. Two series of tests were undertaken, both using axially loaded specimens, and dealing with tension and compression lap joints respectively. The laps ranged in length from 125 to 750 mm, and comprised bars of either 12 or 20 mm diameter. Transverse reinforcement was provided in two of the tension specimens. Greater emphasis was placed on the first series, with fifteen tension specimens being tested. Thirteen of these tests were each completed within a single day but, additionally, two long-term tests were undertaken. In the latter, a constant load was sustained for up to 81 days. The measurements clearly showed the changing behaviour of the specimens, first as transverse cracks developed and subsequently as failure of the lap joint was approached. The comprehensive analysis of the test results includes a comparison of the ultimate behaviour of these joints with existing design proposals and regulations. The detailed information provided by the strain measurements enables the justification of design assumptions regarding lap joint behaviour, and thus lends greater confidence to existing design regulations. The results from five compression specimens were analysed and compared with the tension tests. The significant contribution to force transfer made by the bearing of the free end of the steel against the concrete was evident. The specimens were loaded to the rig capacity without failing. Additional strain measurements were taken in one tension and one compression specimen by casting embedment gauges within the concrete. These gauges were arranged to measure the circumferential strains in the specimen, and were complemented by strain gauges mounted on the surface of the concrete. The data thus obtained permitted a comparison of the bursting forces set up inside and outside the lap joints. The work showed that some aspects of lap joint behaviour require clarification. Suggestions for further work are included
Global impact of the COVID-19 pandemic on subarachnoid haemorrhage hospitalisations, aneurysm treatment and in-hospital mortality: 1-year follow-up
No full textBackground Prior studies indicated a decrease in the incidences of aneurysmal subarachnoid haemorrhage (aSAH) during the early stages of the COVID-19 pandemic. We evaluated differences in the incidence, severity of aSAH presentation, and ruptured aneurysm treatment modality during the first year of the COVID-19 pandemic compared with the preceding year. Methods We conducted a cross-sectional study including 49 countries and 187 centres. We recorded volumes for COVID-19 hospitalisations, aSAH hospitalisations, Hunt-Hess grade, coiling, clipping and aSAH in-hospital mortality. Diagnoses were identified by International Classification of Diseases, 10th Revision, codes or stroke databases from January 2019 to May 2021. Results Over the study period, there were 16 247 aSAH admissions, 344 491 COVID-19 admissions, 8300 ruptured aneurysm coiling and 4240 ruptured aneurysm clipping procedures. Declines were observed in aSAH admissions (-6.4% (95% CI-7.0% to-5.8%), p=0.0001) during the first year of the pandemic compared with the prior year, most pronounced in high-volume SAH and high-volume COVID-19 hospitals. There was a trend towards a decline in mild and moderate presentations of subarachnoid haemorrhage (SAH) (mild:-5% (95% CI-5.9% to-4.3%), p=0.06; moderate:-8.3% (95% CI-10.2% to-6.7%), p=0.06) but no difference in higher SAH severity. The ruptured aneurysm clipping rate remained unchanged (30.7% vs 31.2%, p=0.58), whereas ruptured aneurysm coiling increased (53.97% vs 56.5%, p=0.009). There was no difference in aSAH in-hospital mortality rate (19.1% vs 20.1%, p=0.12). Conclusion During the first year of the pandemic, there was a decrease in aSAH admissions volume, driven by a decrease in mild to moderate presentation of aSAH. There was an increase in the ruptured aneurysm coiling rate but neither change in the ruptured aneurysm clipping rate nor change in aSAH in-hospital mortality. Trial registration number NCT04934020. © Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ
How medicine could have developed differently: A Tory historiographical analysis of the conflict between allopathic and homoeopathic medicine in America and Britain from 1870 to 1920.
No full textAfter its formulation by Samuel Hahnemann (1755-1843) at the end of the 18th century, homoeopathy spread to Britain and America in the 1820ร. Based upon the principle or law of "similia similibus curentur"- let like be cured by like-homoeopathy presented a serious challenge to allopathic medicine. By the 1870s homoeopaths were part of science, performing the first single blind clinical trial, establishing the action of drugs upon the body by experimentation and investigating the nature of matter. Institutionally established, especially in the U.S., they regularly published statistics demonstrating the superiority of homoeopathic treatment in both general practice and in hospitals. Allopaths responded by "nihilating" homoeopathic theory and practice on several levels. Through the language of bacteriology they absorbed key homoeopathic tenets into their own symbolic universe. During the Progressive Era allopaths' ideological resonance with the corporations enabled them to finally vanquish homoeopaths and define medical science along new lines. Homoeopathy's decline in the 1920s was precipitated by its inability to handle experimental error effectively. Yet homoeopaths had raised important epistemological questions about the nature of the relationship between drugs and the human organism. These were never resolved but became repressed along with homoeopathy's scientific history. Since Tory historiography claims that the past informs the future, my aim in recovering homeopathy’s history is to highlight the contemporary importance of these issues for medicine. Only by explicitly addressing these unresolved dilemmas will the Hegelian outworking of Reason be accomplished
Physical and geochemical characterisation of canal sediments in the Black Country, West Midlands.
No full textA thesis submitted in fulfilment of the requirements of the University of
Wolverhampton for the award of the degree of Doctor of Philosophy (Ph.D.)Potentially harmful elements (PHEs) have been researched in a wide variety of disciplines, including pedology, chemistry, pollution science and medicine. Within the scientific community, emphasis has usually been placed on the toxic elements, such as cadmium, chromium, lead and arsenic, but rarely has there been consideration of interactions between PHEs, the sediment matrix and processes occurring in the sediments. Dredging of canals is needed for navigability purposes and consequently testing of dredged sediments (to assess whether sediments are hazardous) and landfilling can be costly for British Waterways facing constantly changing regulations and reduction in government grants. PHE mobility and availability in canal sediments can be affected by oxygen availability, pH and Redox. Remediation is thus becoming a priority for British Waterways to limit their operational costs. Zeolites, a type of remediation tool, have been widely studied in the past 30 years due to their attractive properties, such as molecular-sieving, high cation exchange capacities and their affinity for PHEs. The pilot study to investigate the efficiency of the clinoptilolite showed that there was a concentration difference between PHEs adsorbed by the clinoptilolite and the PHE concentration lost from the sediments from three sites in the West Midlands. Thorough characterisation of the sediments was needed to understand the speciation of the PHEs and the secondary processes occurring in the sediments. The different components of the sediments were analysed using various analytical methods, such as X-Ray Fluorescence spectroscopy (XRF), particle size and X-ray Diffraction (XRD) for the solid-inorganic phase, Ion Chromatography (IC) and Inductively Coupled Plasma-Optical Emissions Spectroscopy (ICP-OES) for the liquid phase (pore water), Gas Chromatography-Mass Spectrometry (GC-MS) and organic loss on ignition for the organic phase, pH and Redox for the electrochemistry of the sediments and Scanning Electron Microscope with Energy Dispersive X-Ray analysis (SEM-EDX) for microscopy and imaging. The British Geological Survey (BGS) sequential extraction method was used to investigate the different phases in the sediments. pH remained near neutral for all three sites and Redox remained anoxic. Organic contents for all three sites were around 30% and contained most of the polycyclic aromatic hydrocarbons considered hazardous. Pore water showed only high concentrations of sulphates but low concentrations of PHEs, suggesting PHEs were not mobile. Sequential extraction confirmed the other results showing that PHEs were mainly associated with stable phases, such as iron and manganese oxides or sulphides. The results have been taken into consideration to design a new remediation strategy to maximise efficiency of the zeolite
Global Effect of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events A 1-Year Follow-up
No full textBackground and Objectives Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020). Methods We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases. Results There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations. Discussion There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year. © 2023 Lippincott Williams and Wilkins. All rights reserved
