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- Goni, Maria Fernanda Sanchez, et al.
(författare)
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The ACER pollen and charcoal database : a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
- 2017
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 9:2, s. 679-695
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Tidskriftsartikel (refereegranskat)abstract
- Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (C-14, U-234/Th-230, optically stimulated luminescence (OSL), Ar-40/Ar-39-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access (TM) at https://doi. org/10.1594/PANGAEA. 870867.
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- Wang, Allen Y., et al.
(författare)
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Rat model of chronic tympanic membrane perforation : A longitudinal histological evaluation of underlying mechanisms
- 2017
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Ingår i: International Journal of Pediatric Otorhinolaryngology. - : Elsevier BV. - 0165-5876 .- 1872-8464. ; 93, s. 88-96
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate histologically the progressive development and underlying mechanisms of chronic tympanic membrane perforation (TMP) in a rat model using a two-weeks ventilation tube (VT) treatment combined with topical application of mitomycin Cidexamethasone (VT-MID), compared with normal tympanic membrane and acute TMPs. Methods: Fifty male Sprague-Dawley rats were divided into three experimental groups: a normal control group (n = 5), an acute TMP group (n = 5) (i.e. 3 days post-myringotomy) and a VT-M/D group (n = 40). The TMs were regularly assessed by otoscopy. The normal control animals were sacrificed on day 0 and the acute TMP group was sacrificed 3 days post-myringotomy for histological and immunohistochemical evaluations. The VT-M/D group was sacrificed at various time points - 14 and 17 days, 3, 4, 6, 8 and 10 weeks. Results: On longitudinal histological examination, compared with normal TM and acute TMP, the perforation edges at the later time points illustrated thickened stratified squamous epithelium rimming around the edges, significant increase in keratin and collagen deposition, increased macrophage infiltration as well as reduced cellular proliferation. Three phases of TMP healing process were identified the acute healing phase (3-17 days), the transition phase (3-4 weeks) and the chronic phase (6-10 weeks). Conclusion: Based on the histological results of this study, the progressive development of chronic TMPs appeared to be associated with increased epidermal thickening, collagen and keratin deposition, macrophage infiltration and reduced cellular proliferation. After the 3-4 weeks of transition phase, the TMPs seemed to have transformed into a non-healing chronic TMP between 6 and 10 weeks. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
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