Institution
University of St Andrews
Education•St Andrews, Fife, United Kingdom•
About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.
Topics: Population, Laser, Planet, Galaxy, Stars
Papers published on a yearly basis
Papers
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TL;DR: It is argued that model ages should be calculated using the composition of new continental crust, which is generally more enriched isotopically than the depleted mantle, to provide a better constraint on when the continental crust was generated.
Abstract: When and how the continental crust was generated remains a fundamental question in Earth sciences. It has been widely believed that the trace element–enriched continental crust and the depleted upper mantle are complementary reservoirs, and that the continental crust has grown from the depleted upper mantle ( 1 , 2 ). Model ages for neodymium (Nd) and hafnium (Hf) isotopes reflect when new continental crust was generated ( 2 ), and traditionally they have been calculated for crust derived from the depleted mantle (see the figure, left panel). The implication is that the isotope composition of the depleted mantle is similar to that of new continental crustal material as it is extracted from the mantle. However, the isotope composition of island arc rocks, and hence of new continental crust, is different from that of the depleted mantle ( 3 , 4 ). We argue that model ages should be calculated using the composition of new continental crust, which is generally more enriched isotopically than the depleted mantle.
327 citations
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TL;DR: The calculations of the surface tension, elastic strain energy, interlayer coupling energy, and Coulomb force indicated that the asymmetrical environment is the principal driving force of the cleavage of the single sheets of H2Ti3O7 from the plates and the formation of the multiwall spiral nanotubes.
Abstract: Formation mechanism of H2Ti3O7 nanotubes by single-step reaction of crystalline TiO2 and NaOH has been investigated via transmission electron microscopy examinations of series specimens with different reaction times and extensive ab initio calculations. It was found that the growth mechanism includes several steps. Crystalline TiO2 reacts with NaOH, forming a highly disordered phase, which recrystallized into some H2Ti3O7 thin plates. H-deficiency on the top surface leads to an asymmetrical environment for the surface Ti3O2-7 layer. The calculations of the surface tension, elastic strain energy, interlayer coupling energy, and Coulomb force indicated that the asymmetrical environment is the principal driving force of the cleavage of the single sheets of H2Ti3O7 from the plates and the formation of the multiwall spiral nanotubes.
326 citations
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Space Telescope Science Institute1, Johns Hopkins University2, University of Kentucky3, University of Pittsburgh4, University of Wisconsin-Madison5, New Mexico State University6, Carnegie Institution for Science7, University of Chile8, New York University9, University of Utah10, Institute for the Physics and Mathematics of the Universe11, Nanjing University12, University of Texas at Austin13, Max Planck Society14, University of Iowa15, University of Washington16, National Autonomous University of Mexico17, Lawrence Berkeley National Laboratory18, Open University19, University of St Andrews20
TL;DR: In this paper, the authors describe the MaNGA Data Reduction Pipeline algorithms and centralized metadata framework that produce sky-subtracted spectrophotometrically calibrated spectra and rectified three-dimensional data cubes that combine individual dithered observations.
Abstract: Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an optical fiber-bundle integral-field unit (IFU) spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). With a spectral coverage of 3622–10354 A and an average footprint of ~500 arcsec2 per IFU the scientific data products derived from MaNGA will permit exploration of the internal structure of a statistically large sample of 10,000 low-redshift galaxies in unprecedented detail. Comprising 174 individually pluggable science and calibration IFUs with a near-constant data stream, MaNGA is expected to obtain ~100 million raw-frame spectra and ~10 million reduced galaxy spectra over the six-year lifetime of the survey. In this contribution, we describe the MaNGA Data Reduction Pipeline algorithms and centralized metadata framework that produce sky-subtracted spectrophotometrically calibrated spectra and rectified three-dimensional data cubes that combine individual dithered observations. For the 1390 galaxy data cubes released in Summer 2016 as part of SDSS-IV Data Release 13, we demonstrate that the MaNGA data have nearly Poisson-limited sky subtraction shortward of ~8500 A and reach a typical 10σ limiting continuum surface brightness μ = 23.5 AB arcsec-2 in a five-arcsecond-diameter aperture in the g-band. The wavelength calibration of the MaNGA data is accurate to 5 km s-1 rms, with a median spatial resolution of 2.54 arcsec FWHM (1.8 kpc at the median redshift of 0.037) and a median spectral resolution of σ = 72 km s-1.
326 citations
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TL;DR: In this paper, the relative importance of bond strength, steric effects, and polarity in determining the rate and orientation of free radical subsitution and free radical addition reaction is considered.
Abstract: The relative importance of bond strength, steric effects, and polarity in determining the rate and orientation of free radical subsitution and free radical addition reaction is considered. The factors which control substitution reaction (radical transfer reaction) are gathered together as five “rules”, and a similar five “rules” are proposed for addition rections. These “rules” are shown to be special cases of two “laws” which govern all free radical reactions.
325 citations
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Estonian Biocentre1, University of Tartu2, University of Cambridge3, University of California, Berkeley4, Arizona State University5, Armenian National Academy of Sciences6, Russian Academy of Sciences7, University of Auckland8, Pennsylvania State University9, University of Winchester10, Wellcome Trust Sanger Institute11, University of Copenhagen12, Kazan Federal University13, Bashkir State University14, Georgia Institute of Technology15, University of Pennsylvania16, Centre national de la recherche scientifique17, Eijkman Institute for Molecular Biology18, Massey University19, University of Dhaka20, Aarhus University21, Griffith University22, Josip Juraj Strossmayer University of Osijek23, Academy of Sciences of Uzbekistan24, Kuban State Medical University25, Nazarbayev University26, L.N.Gumilyov Eurasian National University27, North-Eastern Federal University28, Academy of Medical Sciences, United Kingdom29, Anthony Nolan30, University College London31, University of St Andrews32, University of Kharkiv33, International Burch University34, National Academy of Sciences of Belarus35, Radboud University Nijmegen36, King Abdullah University of Science and Technology37, Stanford University38, University of Arizona39, Stony Brook University40, University Hospital of North Norway41, Estonian Academy of Sciences42
TL;DR: A study of 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples, infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky, and hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males.
Abstract: It is commonly thought that human genetic diversity in non-African populations was shaped primarily by an out-of-Africa dispersal 50-100 thousand yr ago (kya). Here, we present a study of 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples. Applying ancient DNA calibration, we date the Y-chromosomal most recent common ancestor (MRCA) in Africa at 254 (95% CI 192-307) kya and detect a cluster of major non-African founder haplogroups in a narrow time interval at 47-52 kya, consistent with a rapid initial colonization model of Eurasia and Oceania after the out-of-Africa bottleneck. In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky. We hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males.
325 citations
Authors
Showing all 16531 results
Name | H-index | Papers | Citations |
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Yi Chen | 217 | 4342 | 293080 |
Paul M. Thompson | 183 | 2271 | 146736 |
Ian J. Deary | 166 | 1795 | 114161 |
Dongyuan Zhao | 160 | 872 | 106451 |
Mark J. Smyth | 153 | 713 | 88783 |
Harry Campbell | 150 | 897 | 115457 |
William J. Sutherland | 148 | 966 | 94423 |
Thomas J. Smith | 140 | 1775 | 113919 |
John A. Peacock | 140 | 565 | 125416 |
Jean-Marie Tarascon | 136 | 853 | 137673 |
David A. Jackson | 136 | 1095 | 68352 |
Ian Ford | 134 | 678 | 85769 |
Timothy J. Mitchison | 133 | 404 | 66418 |
Will J. Percival | 129 | 473 | 87752 |
David P. Lane | 129 | 568 | 90787 |