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Institution

University of St Andrews

EducationSt 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
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Journal ArticleDOI
14 Jan 2011-Science
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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
Monika Karmin1, Monika Karmin2, Lauri Saag2, Lauri Saag1, Mário Vicente3, Melissa A. Wilson Sayres4, Melissa A. Wilson Sayres5, Mari Järve1, Ulvi Gerst Talas2, Siiri Rootsi1, Anne-Mai Ilumäe2, Anne-Mai Ilumäe1, Reedik Mägi2, Mario Mitt2, Luca Pagani3, Tarmo Puurand2, Zuzana Faltyskova3, Florian Clemente3, Alexia Cardona3, Ene Metspalu1, Ene Metspalu2, Hovhannes Sahakyan6, Hovhannes Sahakyan1, Bayazit Yunusbayev7, Bayazit Yunusbayev1, Georgi Hudjashov1, Georgi Hudjashov8, Michael DeGiorgio9, Eva Liis Loogväli1, Christina A. Eichstaedt3, Mikk Eelmets2, Mikk Eelmets1, Gyaneshwer Chaubey1, Kristiina Tambets1, S. S. Litvinov7, S. S. Litvinov1, Maru Mormina10, Yali Xue11, Qasim Ayub11, Grigor Zoraqi, Thorfinn Sand Korneliussen4, Thorfinn Sand Korneliussen12, Farida Akhatova13, Farida Akhatova14, Joseph Lachance15, Joseph Lachance16, Sarah A. Tishkoff16, Kuvat T. Momynaliev, François-Xavier Ricaut17, Pradiptajati Kusuma17, Pradiptajati Kusuma18, Harilanto Razafindrazaka17, Denis Pierron17, Murray P. Cox19, Gazi Nurun Nahar Sultana20, Rane Willerslev21, Craig Muller12, Michael C. Westaway22, David M. Lambert22, Vedrana Škaro23, Lejla Kovacevic, Shahlo Turdikulova24, Dilbar Dalimova24, Rita Khusainova14, Rita Khusainova7, N. N. Trofimova7, N. N. Trofimova1, V. L. Akhmetova7, I. M. Khidiyatova7, I. M. Khidiyatova14, Daria V. Lichman, Jainagul Isakova, Elvira Pocheshkhova25, Zhaxylyk Sabitov26, Zhaxylyk Sabitov27, Nikolay A. Barashkov28, Pagbajabyn Nymadawa29, Evelin Mihailov2, Joseph Wee Tien Seng, Irina Evseeva30, Andrea Bamberg Migliano31, S M Abdullah, George Andriadze32, Dragan Primorac, L. A. Atramentova33, Olga Utevska33, Levon Yepiskoposyan6, Damir Marjanović34, Alena Kushniarevich35, Alena Kushniarevich1, Doron M. Behar1, Christian Gilissen36, Lisenka E.L.M. Vissers36, Joris A. Veltman36, Elena Balanovska7, Miroslava Derenko7, Boris Malyarchuk7, Andres Metspalu2, Sardana A. Fedorova28, Anders Eriksson3, Anders Eriksson37, Andrea Manica3, Fernando L. Mendez38, Tatiana M. Karafet39, Krishna R. Veeramah40, Neil Bradman, Michael F. Hammer39, Ludmila P. Osipova, Oleg Balanovsky7, Elza Khusnutdinova14, Elza Khusnutdinova7, Knut Johnsen41, Maido Remm2, Mark G. Thomas31, Chris Tyler-Smith11, Peter A. Underhill38, Eske Willerslev12, Rasmus Nielsen4, Mait Metspalu1, Mait Metspalu2, Richard Villems42, Richard Villems2, Richard Villems1, Toomas Kivisild1, Toomas Kivisild3 
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

NameH-indexPapersCitations
Yi Chen2174342293080
Paul M. Thompson1832271146736
Ian J. Deary1661795114161
Dongyuan Zhao160872106451
Mark J. Smyth15371388783
Harry Campbell150897115457
William J. Sutherland14896694423
Thomas J. Smith1401775113919
John A. Peacock140565125416
Jean-Marie Tarascon136853137673
David A. Jackson136109568352
Ian Ford13467885769
Timothy J. Mitchison13340466418
Will J. Percival12947387752
David P. Lane12956890787
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023127
2022387
20211,998
20201,996
20192,059
20181,946