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https://www.readbyqxmd.com/read/28281650/a-high-resolution-history-of-the-south-american-monsoon-from-last-glacial-maximum-to-the-holocene
#1
Valdir F Novello, Francisco W Cruz, Mathias Vuille, Nicolás M Stríkis, R Lawrence Edwards, Hai Cheng, Suellyn Emerick, Marcos S de Paula, Xianglei Li, Eline de S Barreto, Ivo Karmann, Roberto V Santos
The exact extent, by which the hydrologic cycle in the Neotropics was affected by external forcing during the last deglaciation, remains poorly understood. Here we present a new paleo-rainfall reconstruction based on high-resolution speleothem δ(18)O records from the core region of the South American Monsoon System (SAMS), documenting the changing hydrological conditions over tropical South America (SA), in particular during abrupt millennial-scale events. This new record provides the best-resolved and most accurately constrained geochronology of any proxy from South America for this time period, spanning from the Last Glacial Maximum (LGM) to the mid-Holocene...
March 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28261543/efficient-implementation-of-a-local-tomography-reconstruction-algorithm
#2
Pierre Paleo, Alessandro Mirone
We propose an efficient implementation of an interior tomography reconstruction method based on a known subregion. This method iteratively refines a reconstruction, aiming at reducing the local tomography artifacts. To cope with the ever increasing data volumes, this method is highly optimized on two aspects: firstly, the problem is reformulated to reduce the number of variables, and secondly, the operators involved in the optimization algorithms are efficiently implemented. Results show that [Formula: see text] slices can be processed in tens of seconds, while being beyond the reach of equivalent exact local tomography method...
2017: Advanced Structural and Chemical Imaging
https://www.readbyqxmd.com/read/28256409/-the-emergence-of-obstetrical-mechanism-from-lucy-to-homo-sapiens
#3
P Frémondière, L Thollon, F Marchal
The evolutionary history of modern birth mechanism is now a renewed interest in obstetrical papers. The purpose of this work is to review the literature in paleo-obstetrical field. Our analysis focuses on paleo-obstetrical hypothesis, from 1960 to the present day, based on the reconstruction of fossil pelvis. Indeed, these pelvic reconstructions usually provide an opportunity to make an obstetrical assumption in our ancestors. In this analysis, we show that modern birth mechanism takes place during the emergence of our genus 2 million years ago...
February 27, 2017: Gynecol Obstet Fertil Senol
https://www.readbyqxmd.com/read/28231621/the-biogeography-of-tropical-reef-fishes-endemism-and-provinciality-through-time
#4
Peter F Cowman, Valeriano Parravicini, Michel Kulbicki, Sergio R Floeter
The largest marine biodiversity hotspot straddles the Indian and Pacific Oceans, driven by taxa associated with tropical coral reefs. Centred on the Indo-Australian Archipelago (IAA), this biodiversity hotspot forms the 'bullseye' of a steep gradient in species richness from this centre to the periphery of the vast Indo-Pacific region. Complex patterns of endemism, wide-ranging species and assemblage differences have obscured our understanding of the genesis of this biodiversity pattern and its maintenance across two-thirds of the world's oceans...
February 23, 2017: Biological Reviews of the Cambridge Philosophical Society
https://www.readbyqxmd.com/read/28220301/evidence-that-higher-co2-increases-tree-growth-sensitivity-to-temperature-a-comparison-of-modern-and-paleo-oaks
#5
Steven L Voelker, Michael C Stambaugh, J Renée Brooks, Frederick C Meinzer, Barbara Lachenbruch, Richard P Guyette
To test tree growth sensitivity to temperature under different ambient CO2 concentrations, we determined stem radial growth rates as they relate to variation in temperature during the last deglacial period, and compare these to modern tree growth rates as they relate to spatial variation in temperature across the modern species distributional range. Paleo oaks were sampled from Northern Missouri, USA and compared to a pollen-based, high-resolution paleo temperature reconstruction from Northern Illinois, USA...
April 2017: Oecologia
https://www.readbyqxmd.com/read/28214513/molecular-dynamics-simulation-study-of-the-effect-of-glycerol-dialkyl-glycerol-tetraether-hydroxylation-on-membrane-thermostability
#6
Carme Huguet, Susanne Fietz, Antoni Rosell-Melé, Xavier Daura, Lionel Costenaro
Archaeal tetraether membrane lipids span the whole membrane width and present two C40 isoprenoid chains bound by two glycerol groups (or one glycerol and calditol). These lipids confer stability and maintain the membrane fluidity in mesophile to extremophile environments, making them very attractive for biotechnological applications. The isoprenoid lipid composition in archaeal membranes varies with temperature, which has placed these lipids in the focus of paleo-climatological studies for over a decade. Non-hydroxylated isoprenoid archaeal lipids are typically used as paleo-thermometry proxies, but recently identified hydroxylated (OH) derivatives have also been proposed as temperature proxies...
February 16, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28212707/astrobiological-implications-of-dim-light-phototrophy-in-deep-sea-red-clays
#7
Anindita Das, Tanya Singh, P A LokaBharathi, Prashant K Dhakephalkar, Sweta Mallik, Pranav R Kshirsagar, N H Khadge, B Nagender Nath, Satadru Bhattacharya, Aditya Kumar Dagar, Prabhjot Kaur, Dwijesh Ray, Anil D Shukla, Christabelle E G Fernandes, Sheryl O Fernandes, Tresa Remya A Thomas, Mamatha S S, Babu Shashikant Mourya, Ram Murti Meena
Red clays of Central Indian Basin (CIB) under influence of trace of Rodriguez Triple Junction exhibited chemoautotrophy, low temperature hydrothermal alterations and photoautotrophic potential. Seamount flank TVBC-08, hosting such signatures revealed dominance of aerobic anoxygenic phototroph Erythrobacter, with 93% of total 454 pyrosequencing tags. Subsequently, enrichments for both aerobic (Erythrobacter) and anaerobic anoxygenic phototrophs (green and purple sulphur bacteria) under red and white LED light illumination, with average irradiance 30...
February 2017: Life Sciences in Space Research
https://www.readbyqxmd.com/read/28192962/experimental-confirmation-of-isotope-fractionation-in-thiomolybdates-using-ion-chromatographic-separation-and-detection-by-multicollector-icpms
#8
Carolin F Kerl, Regina Lohmayer, Elvira Bura-Nakić, Derek Vance, Britta Planer-Friedrich
Molybdenum (98)Mo/(95)Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO4(2-)) is quantitatively transformed to tetrathiomolybdate (MoS4(2-)) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS)...
February 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192471/the-abundance-and-diversity-of-arbuscular-mycorrhizal-fungi-are-linked-to-the-soil-chemistry-of-screes-and-to-slope-in-the-alpic-paleo-endemic-berardia-subacaulis
#9
Gabriele Casazza, Erica Lumini, Enrico Ercole, Francesco Dovana, Maria Guerrina, Annamaria Arnulfo, Luigi Minuto, Anna Fusconi, Marco Mucciarelli
Berardia subacaulis Vill. is a monospecific genus that is endemic to the South-western Alps, where it grows on alpine screes, which are extreme habitats characterized by soil disturbance and limiting growth conditions. Root colonization by arbuscular mycorrhizal fungi (AMF) is presumably of great importance in these environments, because of its positive effect on plant nutrition and stress tolerance, as well as on structuring the soil. However, there is currently a lack of information on this topic. In this paper, we tested which soil characteristics and biotic factors could contribute to determining the abundance and community composition of AMF in the roots of B...
2017: PloS One
https://www.readbyqxmd.com/read/28187385/paleo-environmental-record-of-polycyclic-aromatic-hydrocarbons-and-polychlorobiphenyls-at-the-peripheral-site-gv7-in-victoria-land-east-antarctica
#10
Stefania Giannarelli, Alessio Ceccarini, Chiara Tiribilli, Rachele Spreafico, Sandro Francesconi, Roger Fuoco
In this paper we investigated the presence of Polycyclic Aromatic Hydrocarbons and Polychlorobiphenyls in a 50-m deep snow/firn core collected at the peripheral site GV7 in East Antarctica during the 2013-2014 XXIX Italian expedition. The concentration depth profile was obtained on the basis of the total concentration of fourteen PAHs and seven PCBs individually determined by gas chromatography triple quadrupole mass spectrometry. Both classes of pollutants showed synchronized concentration vs time profile throughout the whole period of time covered by the snow/firn core (1892-2012)...
May 2017: Chemosphere
https://www.readbyqxmd.com/read/28168029/geographical-differentiation-of-the-euchiloglanis-fish-complex-teleostei-siluriformes-in-the-hengduan-mountain-region-china-phylogeographic-evidence-of-altered-drainage-patterns
#11
Yanping Li, Arne Ludwig, Zuogang Peng
The uplift of the Tibetan Plateau caused significant ecogeographical changes that had a major impact on the exchange and isolation of regional fauna and flora. Furthermore, Pleistocene glacial oscillations were linked to temporal large-scale landmass and drainage system reconfigurations near the Hengduan Mountain Region and might have facilitated speciation and promoted biodiversity in southwestern China. However, strong biotic evidence supporting this role is lacking. Here, we use the Euchiloglanis fish species complex as a model to demonstrate the compound effects of the Tibetan Plateau uplift and Pleistocene glacial oscillations on species formation in this region...
February 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28064314/-gene-pool-of-siberian-tatars-five-ways-of-origin-for-five-subethnic-groups
#12
A T Agdzhoyan, E V Balanovska, A D Padyukova, D O Dolinina, M A Kuznetsova, V V Zaporozhchenko, R A Skhalyakho, S M Koshel, M K Zhabagin, Y M Yusupov, Kh Kh Mustafin, M V Ulyanova, Z A Tychinskih, M B Lavryashina, O P Balanovsky
Siberian Tatars form the largest Turkic-speaking ethnic group in Western Siberia. The group has a complex hierarchical system of ethnographically diverse populations. Five subethnic groups of Tobol-Irtysh Siberian Tatars (N = 388 samples) have been analyzed for 50 informative Y-chromosomal SNPs. The subethnic groups have been found to be extremely genetically diverse (FST = 21%), so the Siberian Tatars form one of the strongly differentiated ethnic gene pools in Siberia and Central Asia. Every method employed in our studies indicates that different subethnic groups formed in different ways...
November 2016: Molekuliarnaia Biologiia
https://www.readbyqxmd.com/read/28009565/a-practical-local-tomography-reconstruction-algorithm-based-on-a-known-sub-region
#13
Pierre Paleo, Michel Desvignes, Alessandro Mirone
A new method to reconstruct data acquired in a local tomography setup is proposed. This method uses an initial reconstruction and refines it by correcting the low-frequency artifacts, known as the cupping effect. A basis of Gaussian functions is used to correct the initial reconstruction. The coefficients of this basis are found by optimizing iteratively a fidelity term under the constraint of a known sub-region. Using a coarse basis reduces the degrees of freedom of the problem while actually correcting the cupping effect...
January 1, 2017: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/28008083/infidelity-in-the-outback-climate-signal-recorded-in-%C3%AE-18o-of-leaf-but-not-branch-cellulose-of-eucalypts-across-an-australian-aridity-gradient
#14
Alexander W Cheesman, Lucas A Cernusak
The isotopic composition of leaf water in terrestrial plants is highly dependent upon a plant's environment. This isotopic signature can become integrated into organic molecules, allowing the isotopic composition of biomarkers such as cellulose to be used as sensitive paleo and climatic proxies. However, the mechanisms by which cellulose isotopic composition reflect environmental conditions are complex, and may vary between leaf and woody tissues. To date few empirical tests have been made on the relative roles of leaf-water enrichment and source water on the isotopic composition of leaf and wood cellulose within the same plant...
December 21, 2016: Tree Physiology
https://www.readbyqxmd.com/read/27997756/evidence-of-molybdenum-association-with-particulate-organic-matter-under-sulfidic-conditions
#15
T W Dahl, A Chappaz, J Hoek, C J McKenzie, S Svane, D E Canfield
The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented by sulfate-reducing bacteria). Molybdenum was immobilized at the surface of both living cells and dead/lysed cells, but not in cell-free control experiments. Experiments were carried out at four different Mo concentrations (0...
December 20, 2016: Geobiology
https://www.readbyqxmd.com/read/27997045/dynamics-of-escherichia-coli-type-i-e-crispr-spacers-over-42-000-years
#16
Ekaterina Savitskaya, Anna Lopatina, Sofia Medvedeva, Mikhail Kapustin, Sergey Shmakov, Alexey Tikhonov, Irena I Artamonova, Maria Logacheva, Konstantin Severinov
CRISPR-Cas are nucleic acids-based prokaryotic immune systems. CRISPR arrays accumulate spacers from foreign DNA and provide resistance to mobile genetic elements containing identical or similar sequences. Thus, the set of spacers present in a given bacterium can be regarded as a record of encounters of its ancestors with genetic invaders. Such records should be specific for different lineages and change with time, as earlier acquired spacers get obsolete and are lost. Here, we studied Type I-E CRISPR spacers of Escherichia coli from extinct pachyderm...
December 20, 2016: Molecular Ecology
https://www.readbyqxmd.com/read/27991953/barium-and-its-importance-as-an-indicator-of-paleo-productivity
#17
Bianca T P Liguori, Marcelo G DE Almeida, Carlos E DE Rezende
Barium (Ba) is a trace element which occurs predominantly as barite mineral (BaSO4) in the marine environment. Previous work suggests that barite concentrations are related to the organic carbon flux and marine biological debris in the water column suggesting a direct or indirect involvement in the marine biological cycling. In addition, barite has a high preservation rate (~30%) in sediments and it is less affected by early diagenesis than other proxies for productivity such as carbonates (~10%) and organic carbon (~1%), for example...
October 2016: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/27991945/first-occurrence-and-paleo-ecological-implications-of-insects-orthoptera-ensifera-gryllidae-in-the-romualdo-member-of-the-santana-formation-eo-cretaceous-of-the-araripe-basin
#18
Luís C B Freitas, Geraldo J B DE Moura, Antônio A F Saraiva
The Romualdo Member of the Santana Formation, a lithostatigraphic unit attributed to a marine intrusion, is famous for its preserved fossils in calcareous concretions, which stand out for their diversity and excellent preservation levels. This paper aims to record the first occurrence of the Class Insecta in the Romualdo Member of the Santana Formation of the Araripe Basin, as well as to describe and discuss the paleo-ecological implications of such finding. The first occurrence of the order Orthoptera (family Gryllidae) is presented for this unit...
October 2016: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/27911776/evaluating-early-warning-indicators-of-critical-transitions-in-natural-aquatic-ecosystems
#19
Alena Sonia Gsell, Ulrike Scharfenberger, Deniz Özkundakci, Annika Walters, Lars-Anders Hansson, Annette B G Janssen, Peeter Nõges, Philip C Reid, Daniel E Schindler, Ellen Van Donk, Vasilis Dakos, Rita Adrian
Ecosystems can show sudden and persistent changes in state despite only incremental changes in drivers. Such critical transitions are difficult to predict, because the state of the system often shows little change before the transition. Early-warning indicators (EWIs) are hypothesized to signal the loss of system resilience and have been shown to precede critical transitions in theoretical models, paleo-climate time series, and in laboratory as well as whole lake experiments. The generalizability of EWIs for detecting critical transitions in empirical time series of natural aquatic ecosystems remains largely untested, however...
December 13, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27894994/a-new-genus-of-anostomidae-ostariophysi-characiformes-diversity-phylogeny-and-biogeography-based-on-cytogenetic-molecular-and-morphological-data
#20
Jorge L Ramirez, José L O Birindelli, Pedro M Galetti
A new genus of Anostomidae (Characiformes) is described to include ten valid extant species previously classified in Leporinus or Hypomasticus and distributed throughout most major river basins in South America: L. brinco, L. conirostris, L. elongatus, H. garmani, L. macrocephalus, L. muyscorum, L. obtusidens, L. piavussu, L. reinhardti, and L. trifasciatus. The monophyly of Megaleporinus is well-supported in a phylogenetic analysis based on two mitochondrial and three nuclear genes, as well as its sister group relationship to Abramites...
November 25, 2016: Molecular Phylogenetics and Evolution
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