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  • 1
    Publication Date: 2015-07-15
    Description: Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sigl, M -- Winstrup, M -- McConnell, J R -- Welten, K C -- Plunkett, G -- Ludlow, F -- Buntgen, U -- Caffee, M -- Chellman, N -- Dahl-Jensen, D -- Fischer, H -- Kipfstuhl, S -- Kostick, C -- Maselli, O J -- Mekhaldi, F -- Mulvaney, R -- Muscheler, R -- Pasteris, D R -- Pilcher, J R -- Salzer, M -- Schupbach, S -- Steffensen, J P -- Vinther, B M -- Woodruff, T E -- England -- Nature. 2015 Jul 30;523(7562):543-9. doi: 10.1038/nature14565. Epub 2015 Jul 8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512, USA. ; Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA. ; Space Sciences Laboratory, University of California, Berkeley, California 94720, USA. ; School of Geography, Archaeology and Palaeoecology, Queen's University Belfast, Belfast BT7 1NN, UK. ; Yale Climate and Energy Institute, and Department of History, Yale University, New Haven, Connecticut 06511, USA. ; 1] Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland [2] Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland [3] Global Change Research Centre AS CR, 60300 Brno, Czech Republic. ; 1] Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA [2] Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA. ; Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark. ; 1] Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland [2] Climate and Environmental Physics, University of Bern, 3012 Bern, Switzerland. ; Alfred-Wegener-Institut Helmholtz-Zentrum fur Polar- und Meeresforschung, 27570 Bremerhaven, Germany. ; Department of History, The University of Nottingham, Nottingham NG7 2RD, UK. ; Department of Geology, Quaternary Sciences, Lund University, 22362 Lund, Sweden. ; British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, UK. ; The Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona 85721, USA. ; Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26153860" target="_blank"〉PubMed〈/a〉
    Keywords: Aerosols/analysis ; Americas ; Antarctic Regions ; Atmosphere/chemistry ; Beryllium ; Carbon Radioisotopes ; *Climate ; Disasters/history ; Europe ; Greenland ; History, Ancient ; History, Medieval ; Ice/analysis ; Radioisotopes ; Radiometric Dating ; Seasons ; Sulfur ; *Temperature ; Time Factors ; Trees/anatomy & histology/growth & development ; Tropical Climate ; Volcanic Eruptions/*history
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-04-13
    Description: Understanding the molecular and cellular mechanisms that mediate magnetosensation in vertebrates is a formidable scientific problem. One hypothesis is that magnetic information is transduced into neuronal impulses by using a magnetite-based magnetoreceptor. Previous studies claim to have identified a magnetic sense system in the pigeon, common to avian species, which consists of magnetite-containing trigeminal afferents located at six specific loci in the rostral subepidermis of the beak. These studies have been widely accepted in the field and heavily relied upon by both behavioural biologists and physicists. Here we show that clusters of iron-rich cells in the rostro-medial upper beak of the pigeon Columbia livia are macrophages, not magnetosensitive neurons. Our systematic characterization of the pigeon upper beak identified iron-rich cells in the stratum laxum of the subepidermis, the basal region of the respiratory epithelium and the apex of feather follicles. Using a three-dimensional blueprint of the pigeon beak created by magnetic resonance imaging and computed tomography, we mapped the location of iron-rich cells, revealing unexpected variation in their distribution and number--an observation that is inconsistent with a role in magnetic sensation. Ultrastructure analysis of these cells, which are not unique to the beak, showed that their subcellular architecture includes ferritin-like granules, siderosomes, haemosiderin and filopodia, characteristics of iron-rich macrophages. Our conclusion that these cells are macrophages and not magnetosensitive neurons is supported by immunohistological studies showing co-localization with the antigen-presenting molecule major histocompatibility complex class II. Our work necessitates a renewed search for the true magnetite-dependent magnetoreceptor in birds.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Treiber, Christoph Daniel -- Salzer, Marion Claudia -- Riegler, Johannes -- Edelman, Nathaniel -- Sugar, Cristina -- Breuss, Martin -- Pichler, Paul -- Cadiou, Herve -- Saunders, Martin -- Lythgoe, Mark -- Shaw, Jeremy -- Keays, David Anthony -- England -- Nature. 2012 Apr 11;484(7394):367-70. doi: 10.1038/nature11046.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Pathology, Dr Bohr-Gasse, 1030 Vienna, Austria.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22495303" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Migration ; Animals ; Beak/anatomy & histology/*cytology ; Columbidae/*anatomy & histology/physiology ; Feathers/cytology/ultrastructure ; Ferrocyanides/analysis ; Immunohistochemistry ; Iron/analysis/*metabolism ; Macrophages/*metabolism/ultrastructure ; *Magnetic Fields ; Magnetic Resonance Imaging ; Neurons/metabolism ; Orientation ; Respiratory Mucosa/cytology/ultrastructure ; *Sensation ; Tomography, Emission-Computed, Single-Photon
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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