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https://www.readbyqxmd.com/read/27924946/the-juvenile-hafnium-isotope-signal-as-a-record-of-supercontinent-cycles
#1
Nicholas J Gardiner, Christopher L Kirkland, Martin J Van Kranendonk
Hf isotope ratios measured in igneous zircon are controlled by magmatic source, which may be linked to tectonic setting. Over the 200-500 Myr periodicity of the supercontinent cycle - the principal geological phenomenon controlling prevailing global tectonic style - juvenile Hf signals, i.e. most radiogenic, are typically measured in zircon from granites formed in arc settings (crustal growth), and evolved zircon Hf signals in granites formed in continent-collision settings (crustal reworking). Interrogations of Hf datasets for excursions related to Earth events commonly use the median value, however this may be equivocal due to magma mixing...
December 7, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27922835/2d-self-assembly-of-phenylene-vinylene-tectons-at-the-liquid-highly-oriented-pyrolytic-graphite-interface-from-chain-length-effects-to-anisotropic-guest-host-dynamics
#2
A Six, A Bocheux, F Charra, F Mathevet, D Kreher, A-J Attias
Here we report the synthesis and characterization of a series of new phenylene-vinylene tectons. The study by scanning tunneling microscopy of their supramolecular self-assembly at the interface between a phenyloctane solution and highly oriented pyrolytic graphite  demonstrates that variation of concentration and length of alkyl chains led to the formation of different networks, a compact one and a nanoporous one, with a fine control of the lattice parameters. The study of guest-host properties of the nanoporous network revealed a selectivity toward guest compounds according to their shape and size...
December 6, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27917328/gps-imaging-of-vertical-land-motion-in-california-and-nevada-implications-for-sierra-nevada-uplift
#3
William C Hammond, Geoffrey Blewitt, Corné Kreemer
We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations...
October 2016: Journal of Geophysical Research. Solid Earth
https://www.readbyqxmd.com/read/27909816/ecological-and-physical-barriers-shape-genetic-structure-of-the-alpine-porcini-boletus-reticuloceps
#4
Bang Feng, Jian Wei Liu, Jianping Xu, Kuan Zhao, Zai Wei Ge, Zhu L Yang
The Alpine porcini, Boletus reticuloceps, is an ectomycorrhizal mushroom distributed in subalpine areas of Southwest China, central China, and Taiwan Island. This distribution pattern makes it an ideal organism to infer how ectomycorrhizal fungi have reacted to historical tectonic and climatic changes, and to illustrate the mechanism for the disjunction of organisms between Southwest China and Taiwan. In this study, we explored the phylogeographic pattern of B. reticuloceps by microsatellite genotyping, DNA sequencing, ecological factor analysis, and species distribution modeling...
December 1, 2016: Mycorrhiza
https://www.readbyqxmd.com/read/27897168/stepwise-onset-of-the-icehouse-world-and-its-impact-on-oligo-miocene-central-asian-mammals
#5
Mathias Harzhauser, Gudrun Daxner-Höck, Paloma López-Guerrero, Olivier Maridet, Adriana Oliver, Werner E Piller, Sylvain Richoz, Margarita A Erbajeva, Thomas A Neubauer, Ursula B Göhlich
Central Asia is a key area to study the impact of Cenozoic climate cooling on continental ecosystems. One of the best places to search for rather continuous paleontological records is the Valley of Lakes in Mongolia with its outstandingly fossil-rich Oligocene and Miocene terrestrial sediments. Here, we investigate the response by mammal communities during the early stage of Earth's icehouse climate in Central Asia. Based on statistical analyses of occurrence and abundance data of 18608 specimens representing 175 mammal species and geochemical (carbon isotopes) and geophysical (magnetic susceptibility) data we link shifts in diversities with major climatic variations...
November 29, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27884104/phylogeography-reveals-an-ancient-cryptic-radiation-in-east-asian-tree-frogs-hyla-japonica-group-and-complex-relationships-between-continental-and-island-lineages
#6
Christophe Dufresnes, Spartak N Litvinchuk, Amaël Borzée, Yikweon Jang, Jia-Tang Li, Ikuo Miura, Nicolas Perrin, Matthias Stöck
BACKGROUND: In contrast to the Western Palearctic and Nearctic biogeographic regions, the phylogeography of Eastern-Palearctic terrestrial vertebrates has received relatively little attention. In East Asia, tectonic events, along with Pleistocene climatic conditions, likely affected species distribution and diversity, especially through their impact on sea levels and the consequent opening and closing of land-bridges between Eurasia and the Japanese Archipelago. To better understand these effects, we sequenced mitochondrial and nuclear markers to determine phylogeographic patterns in East-Asian tree frogs, with a particular focus on the widespread H...
November 23, 2016: BMC Evolutionary Biology
https://www.readbyqxmd.com/read/27843236/mycobacterium-chelonae-in-a-tectonic-corneal-graft
#7
Haziq Raees Chowdhury, Oliver Comyn, Gill Jones, Mayank A Nanavaty
Atypical mycobacterial infections of the cornea can present with nonspecific inflammatory changes and graft rejection, with no obvious focus to culture and a subsequent delay to diagnosis. These pathogens are well documented in the literature following laser-assisted in situ keratomileusis but have rarely been described following corneal transplant surgery. We report a single case of Mycobacterium chelonae keratitis 1 year after tectonic keratoplasty.
September 2016: Oman Journal of Ophthalmology
https://www.readbyqxmd.com/read/27830704/glacial-isostatic-uplift-of-the-european-alps
#8
Jürgen Mey, Dirk Scherler, Andrew D Wickert, David L Egholm, Magdala Tesauro, Taylor F Schildgen, Manfred R Strecker
Following the last glacial maximum (LGM), the demise of continental ice sheets induced crustal rebound in tectonically stable regions of North America and Scandinavia that is still ongoing. Unlike the ice sheets, the Alpine ice cap developed in an orogen where the measured uplift is potentially attributed to tectonic shortening, lithospheric delamination and unloading due to deglaciation and erosion. Here we show that ∼90% of the geodetically measured rock uplift in the Alps can be explained by the Earth's viscoelastic response to LGM deglaciation...
November 10, 2016: Nature Communications
https://www.readbyqxmd.com/read/27827417/micrometre-scale-deformation-observations-reveal-fundamental-controls-on-geological-rifting
#9
Johannes Thun, Ivan Lokmer, Christopher J Bean, Eva P S Eibl, Bergur H Bergsson, Aoife Braiden
Many of the world's largest volcanic eruptions are associated with geological rifting where major fractures open at the Earth's surface, yet fundamental controls on the near-surface response to the rifting process are lacking. New high resolution observations gleaned from seismometer data during the 2014 Bárðarbunga basaltic dyke intrusion in Iceland allow us unprecedented access to the associated graben formation process on both sub-second and micrometre scales. We find that what appears as quasi steady-state near-surface rifting on lower resolution GPS observation comprises discrete staccato-like deformation steps as the upper crust unzips through repetitive low magnitude (MW < 0) failures on fracture patches estimated between 300 m(2) and 1200 m(2) in size...
November 9, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27827413/preservation-of-amorphous-ultrafine-material-a-proposed-proxy-for-slip-during-recent-earthquakes-on-active-faults
#10
Tetsuro Hirono, Satoru Asayama, Shunya Kaneki, Akihiro Ito
The criteria for designating an "Active Fault" not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively...
November 9, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27821756/rapid-conversion-of-an-oceanic-spreading-center-to-a-subduction-zone-inferred-from-high-precision-geochronology
#11
Timothy E Keenan, John Encarnación, Robert Buchwaldt, Dan Fernandez, James Mattinson, Christine Rasoazanamparany, P Benjamin Luetkemeyer
Where and how subduction zones initiate is a fundamental tectonic problem, yet there are few well-constrained geologic tests that address the tectonic settings and dynamics of the process. Numerical modeling has shown that oceanic spreading centers are some of the weakest parts of the plate tectonic system [Gurnis M, Hall C, Lavier L (2004) Geochem Geophys Geosys 5:Q07001], but previous studies have not favored them for subduction initiation because of the positive buoyancy of young lithosphere. Instead, other weak zones, such as fracture zones, have been invoked...
November 22, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27802443/pelage-variation-and-distribution-of-the-black-lion-tamarin-leontopithecus-chrysopygus
#12
Guilherme Siniciato Terra Garbino, Gabriela Cabral Rezende, Claudio Valladares-Padua
The black lion tamarin, Leontopithecus chrysopygus, is endemic to the Atlantic Forest of the interior of the state of São Paulo in Brazil. Since the discovery of the species, authors have described variations in the pelage of L. chrysopygus, but the nature of this variation has remained unknown. We examined museum specimens and living animals to see if the pelage of L. chrysopygus varies individually, geographically or ontogenetically. We reviewed all known locality records of the species, and concluded that the pelage of L...
2016: Folia Primatologica; International Journal of Primatology
https://www.readbyqxmd.com/read/27793079/population-subdivision-of-hydrothermal-vent-polychaete-alvinella-pompejana-across-equatorial-and-easter-microplate-boundaries
#13
Sook-Jin Jang, Eunji Park, Won-Kyung Lee, Shannon B Johnson, Robert C Vrijenhoek, Yong-Jin Won
BACKGROUND: The Equator and Easter Microplate regions of the eastern Pacific Ocean exhibit geomorphological and hydrological features that create barriers to dispersal for a number of animals associated with deep-sea hydrothermal vent habitats. This study examined effects of these boundaries on geographical subdivision of the vent polychaete Alvinella pompejana. DNA sequences from one mitochondrial and eleven nuclear genes were examined in samples collected from ten vent localities that comprise the species' known range from 23°N latitude on the East Pacific Rise to 38°S latitude on the Pacific Antarctic Ridge...
October 28, 2016: BMC Evolutionary Biology
https://www.readbyqxmd.com/read/27791312/determining-the-attenuation-factor-in-molecular-wires-featuring-covalent-and-noncovalent-tectons
#14
Sonia Vela, Stefan Bauroth, Carmen Atienza, Agustín Molina-Ontoria, Dirk M Guldi, Nazario Martín
Hybrid covalent/supramolecular porphyrin-fullerene structures were synthesized as highly efficient molecular wires with a remarkably low attenuation factor (β=0.07±0.01 Å(-1) ). Hydrogen-bonding interactions and p-phenylene oligomers of different lengths are responsible for efficient electron transfer in the molecular wires.
October 28, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27789836/formation-of-the-orientale-lunar-multiring-basin
#15
Brandon C Johnson, David M Blair, Gareth S Collins, H Jay Melosh, Andrew M Freed, G Jeffrey Taylor, James W Head, Mark A Wieczorek, Jeffrey C Andrews-Hanna, Francis Nimmo, James T Keane, Katarina Miljković, Jason M Soderblom, Maria T Zuber
Multiring basins, large impact craters characterized by multiple concentric topographic rings, dominate the stratigraphy, tectonics, and crustal structure of the Moon. Using a hydrocode, we simulated the formation of the Orientale multiring basin, producing a subsurface structure consistent with high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft. The simulated impact produced a transient crater, ~390 kilometers in diameter, that was not maintained because of subsequent gravitational collapse...
October 28, 2016: Science
https://www.readbyqxmd.com/read/27766847/electron-triggered-metamorphism-in-porphyrin-based-self-assembled-coordination-polymers
#16
Christophe Kahlfuss, Sandrine Denis-Quanquin, Nathalie Calin, Elise Dumont, Marco Garavelli, Guy Royal, Saioa Cobo, Eric Saint-Aman, Christophe Bucher
Viologen-centered electron transfer is used to trigger a complete dissociation of a porphyrin-based coordination polymer. In the oxidized state, self-assembly is induced by iterative association of individual porphyrin-based tectons. Dissociation of the self-assembled species is actuated upon changing the redox state of the bipyridium units involved in the tectons from their dicationic state to their radical cation state, the driving force of the disassembling process being the formation of an intramolecularly locked conformation partly stabilized by π-dimerization of both viologen cation radicals...
October 21, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27753078/hydrogeological-studies-to-identify-the-trend-of-concealed-section-of-the-north-tabriz-fault-iran
#17
Hossein Rajabpour, Abdorreza Vaezihir
The North Tabriz Fault (NTF) is the predominant regional-scale tectonic structure in the northwest of Iran. In the east side of the city of Tabriz, a portion of the fault trend has been completely concealed by recent sediments and urbanization. In this paper, some hydrogeological methods are used to locate the concealed sector. As is clear from the pumping tests results, despite the fact that the northern observation wells were closer to the pumping wells than the southern ones, they have not been affected by pumping...
October 17, 2016: Ground Water
https://www.readbyqxmd.com/read/27749920/a-multi-faceted-approach-to-analyse-the-effects-of-environmental-variables-on-geographic-range-and-genetic-structure-of-a-perennial-psammophilous-geophyte-the-case-of-the-sea-daffodil-pancratium-maritimum-l-in-the-mediterranean-basin
#18
Olga De Castro, Antonietta Di Maio, Mirko Di Febbraro, Gennaro Imparato, Michele Innangi, Errol Véla, Bruno Menale
The Mediterranean coastline is a dynamic and complex system which owes its complexity to its past and present vicissitudes, e.g. complex tectonic history, climatic fluctuations, and prolonged coexistence with human activities. A plant species that is widespread in this habitat is the sea daffodil, Pancratium maritimum (Amaryllidaceae), which is a perennial clonal geophyte of the coastal sands of the Mediterranean and neighbouring areas, well adapted to the stressful conditions of sand dune environments. In this study, an integrated approach was used, combining genetic and environmental data with a niche modelling approach, aimed to investigate: (1) the effect of climate change on the geographic range of this species at different times {past (last inter-glacial, LIG; and last glacial maximum, LGM), present (CURR), near-future (FUT)} and (2) the possible influence of environmental variables on the genetic structure of this species in the current period...
2016: PloS One
https://www.readbyqxmd.com/read/27749446/tectonic-descemet-stripping-automated-endothelial-keratoplasty-for-the-management-of-sterile-corneal-perforations-in-decompensated-corneas
#19
Yoav Nahum, Irit Bahar, Massimo Busin
PURPOSE: To report the use of Descemet stripping automated endothelial keratoplasty (DSAEK) for treatment of sterile corneal perforations accompanying endothelial decompensation. METHODS: In this multicenter interventional case series, we reviewed the medical records of all tectonic DSAEK surgeries performed at Villa Serena-Villa Igea private Hospitals (Forlì, Italy) and Rabin Medical Center (Petach Tikva, Israel) between January 2014 and March 2016. RESULTS: Three patients with endothelial decompensation and sterile corneal perforation (n = 2) or impending corneal perforation (n = 1) underwent DSAEK between 2014 and 2015 at Villa Igea Hospital, Forlì, Italy, and Rabin Medical Center, Petach Tikva, Israel...
October 5, 2016: Cornea
https://www.readbyqxmd.com/read/27742299/epidemiological-profile-of-patients-undergoing-urgent-corneal-transplant-in-a-referral-center-in-northeastern-brazil
#20
G K P Cruz, S B da Silva, I C de Azevedo, D P S R P Carvalho, P F Meireles, M A F Júnior, A F Vitor
BACKGROUND: The purpose of the study was to characterize the epidemiological profile and average time on the waiting list of patients undergoing an urgent corneal transplantation (CT) in a referral center in the state of Rio Grande do Norte, northeastern Brazil. METHODS: This cross-sectional study included cases of urgent corneal transplants performed in a referral center from January 2010 to December 2014. Data were collected between January and March 2015. RESULTS: Seventy-four cases of emergency CT were analyzed...
September 2016: Transplantation Proceedings
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