614 research outputs found

    If Hippopotamuses Cannot Swim, How Did They Colonize Islands?

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    Design and analysis of nitinol-embedded silicone membranes for artificial skin

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    THE GENUS URSUS IN EURASIA: DISPERSAL EVENTS AND STRATIGRAPHICAL SIGNIFICANCE

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    On the basis of the results of former studies by the present authors five main groups of bears are recognized: Ursus gr. minimus - thibetanus (black bears), Ursus gr. etruscus (etruscan bears), Ursus gr. arctos (brown bears), Ursus gr. deningei - spelaeus (cave bears) and Ursus gr. maritimus (white bears). Black bears seem to have disappeared from Europe during the Late Pliocene, immigrated again at the beginning of the Middle Pleistocene, and definitively died out in Europe at the beginning of the Late Pleistocene. Etruscan bears occur more or less contemporaneously in the southern areas of Europe and Asia during the Late Pliocene. The Asian branch apparently became extinct at the end of this period, while the European stock survived, giving rise to more advanced representatives during the Early Pleistocene. Brown bears seem to have originated in Asia. This group dispersed widely in holoarctic areas diversifying into a great number of varieties. They reached Europe presumably at the very end of the Early Pleistocene. The arrival of brown bears in Europe is a crucial event, which approximately coincides with the great faunal turnover which marks the Early-Middle Pleistocene transition. Brown bears replaced the etruscan bears, typical of the Villafranchian faunal assemblages, and gave rise to the cave bear line. Cave bears were very successful in Europe during the Middle and Late Pleistocene and disappeared at the end of the last glaciation or even at the very beginning of the Holocene. White bears presumably originated from northern Eurasian brown bear populations during the Late Pleistocene

    A MIOCENE CERVID FROM THE TORRENTE MORRA SEQUENCE (COLLESALVETTI, PISA, ITALY)

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    A well preserved fossil left tibia of artiodactyl was recently found along Torrente Morra, in the surroundings of Collesalvetti (15 Kms South of Pisa). The bone is embedded in Upper Messinian deltaic sediments which outcrop patchily in the area. The specimen can be referred to a primitive cervid and shows morphological characters and proportions very close to those of the tibiae of extant roe deer, Capreolus capreolus. The find is particularly significant because continental mammals have never been reported before from the Miocene deposits of this area. A possible reference to a primitive roe deer would be consistent with Late Miocene macrofloral and palynological evidence from this area, which attest to a transition from a subtropical forested environment to a temperate Mediterranean one.&nbsp

    The tangled cases of Deinogalerix (Late Miocene endemic erinaceid of Gargano) and Galericini (Eulipotyphla, Erinaceidae): A cladistic perspective

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    The Late Miocene giant erinaceid Deinogalerix from Scontrone and Gargano (Italy) is associated with many other vertebrates in deposits of a past island, the \u201cAbruzzo-Apulia Platform\u201d. At Gargano, Deinogalerix is accompanied by the moderately endemized Galericini Apulogalerix. This first extensive cladistic analysis is aimed at defining the relationships of Deinogalerix with characteristic members of the tribe Galericini. The analysis was performed on a matrix of 30 characters and 19 taxa and identified some smaller clades, nested within three major ones. The latter include: (i) a pentatomy of Galerix species, (ii) a polytomy of \u201ctransitional\u201d Galerix\u2013Parasorex species and (iii) a large clade with Parasorex, Schizogalerix and Gargano representatives. Galerix and Parasorex proved to be paraphyletic and Schizogalerix monophyletic. Based on the results of the analysis, Deinogalerix and Apulogalerix have distinct origins, which supports an asynchronous colonization of the island. The line of Deinogalerix possibly stemmed from some eastern species transitional between Galerix and Parasorex around Mammal Neogene (MN) zone 2. Conversely, the line of Apulogalerix originated from a primitive Parasorex ibericus, or a close relative, around MN 9\u201310. Another important result was detecting an impressive early Miocene (MN 2?) radiation of Galericini. Moreover, Schizogalerix and Parasorex originated from eastern Galericini morphologically transitional between Galerix and Parasorex

    NEW LIGHT ON PARASOREX DEPERETI (ERINACEOMORPHA: ERINACEIDAE: GALERICINI) FROM THE LATE MESSINIAN (MN 13) OF THE MONTICINO QUARRY (BRISIGHELLA, FAENZA, ITALY)

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    A large-sized species of Parasorex is common in the MN 13 mammal assemblages from the uppermost Messinian sandy-marly fissure fillings within the Gessoso Solfifera Formation at Brisighella (Northern Apennine). This erinaceid has been classified as Galerix sp. in the first papers on the Brisighella fauna. Later, it was described in detail in an unpublished Ph.D. dissertation by Fanfani (1999), who referred it to Galerix depereti. Van den Hoek Ostende (2001) included G. depereti in the genus Parasorex, Parasorex depereti has been described by Crochet (1986) on scarce material from a few Early Pliocene (MN 14–15) localities of southern France and Spain. Parasorex cf. depereti has been reported from the Early Pliocene fauna of Capo Mannu (Mandriola, Sardinia; Furió and Angelone 2010). The species seems actually distributed in south-western Europe, where it represents the youngest occurrence of the genus Parasorex. The very abundant sample of P. depereti from fissure filling BRS 25 enables a more accurate and comprehensive description of the species. It also permits inspection of the mesial elements of the dentition, which were lacking in the material examined by Crochet (1986). The systematic position of the species has been revisited and compared with those of other Galericini of the Parasorex group

    Activation of Nrf2 in fibroblasts promotes a skin aging phenotype via an Nrf2-miRNA-collagen axis

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    Aging is associated with progressive skin fragility and a tendency to tear, which can lead to severe clinical complications. The transcription factor NRF2 is a key regulator of the cellular antioxidant response, and pharmacological NRF2 activation is a promising strategy for the prevention of age-related diseases. Using a combination of molecular and cellular biology, histology, imaging and biomechanical studies we show, however, that constitutive genetic activation of Nrf2 in fibroblasts of mice suppresses collagen and elastin expression, resulting in reduced skin strength as seen in aged mice. Mechanistically, the "aging matrisome" results in part from direct Nrf2-mediated overexpression of a network of microRNAs that target mRNAs of major skin collagens and other matrix components. Bioinformatics and functional studies revealed high NRF2 activity in aged human fibroblasts in 3D skin equivalents and human skin biopsies, highlighting the translational relevance of the functional mouse data. Together, these results identify activated NRF2 as a promoter of age-related molecular and biomechanical skin features. Keywords: Aging; Collagen; Extracellular matrix; Nrf2; Skin mechanics; miRN

    ContaminatedMixt: An R Package for Fitting Parsimonious Mixtures of Multivariate Contaminated Normal Distributions

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    We introduce the R package ContaminatedMixt, conceived to disseminate the use of mixtures of multivariate contaminated normal distributions as a tool for robust clustering and classification under the common assumption of elliptically contoured groups. Thirteen variants of the model are also implemented to introduce parsimony. The expectationconditional maximization algorithm is adopted to obtain maximum likelihood parameter estimates, and likelihood-based model selection criteria are used to select the model and the number of groups. Parallel computation can be used on multicore PCs and computer clusters, when several models have to be fitted. Differently from the more popular mixtures of multivariate normal and t distributions, this approach also allows for automatic detection of mild outliers via the maximum a posteriori probabilities procedure. To exemplify the use of the package, applications to artificial and real data are presented

    Activation of Nrf2 in fibroblasts promotes a skin aging phenotype via an Nrf2-miRNA-collagen axis

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    Aging is associated with progressive skin fragility and a tendency to tear, which can lead to severe clinical complications. The transcription factor NRF2 is a key regulator of the cellular antioxidant response, and pharmacological NRF2 activation is a promising strategy for the prevention of age-related diseases. Using a combination of molecular and cellular biology, histology, imaging and biomechanical studies we show, however, that constitutive genetic activation of Nrf2 in fibroblasts of mice suppresses collagen and elastin expression, resulting in reduced skin strength as seen in aged mice. Mechanistically, the “aging matrisome” results in part from direct Nrf2-mediated overexpression of a network of microRNAs that target mRNAs of major skin collagens and other matrix components. Bioinformatics and functional studies revealed high NRF2 activity in aged human fibroblasts in 3D skin equivalents and human skin biopsies, highlighting the translational relevance of the functional mouse data. Together, these results identify activated NRF2 as a promoter of age-related molecular and biomechanical skin features
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