1,199 research outputs found

    THE BASAL COMPLEX STRATIGRAPHY OF THE HELMINTHOID MONTE CASSIO FLYSCH: A KEY TO THE EOALPINE TECTONICS OF THE NORTHERN APENNINES

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    Below the Monte Cassio helminthoid Flysch of the type locality, a well exposed basal complex outcrops in which Cenomanian turbidites of up to 200 m thickness are recognized. The bulk of these turbidites, named here Case Baruzzo Sandstone (CBS), consists of thick-bedded silty marlstones with a fine arenaceous base and represents the oldest siliciclastic input within the succession of the Cassio tectonic unit. The Case Baruzzo Sandstone lies unconformably on the Palombini shale of Hauterivian-Aptian age and on stratified packets of Jurassic-Cretaceous formations with Austroalpine affinity (Radiolarites, Aptici Shale and Maiolica). The Cenomanian CBS are unconformably overlain by Varicoloured Clay of Santonian - Campanian age and affected by soft-sediment deformations. The petrography of the CBS shows two petrofacies indicating (1) a direct provenance from their substrate and (2) an extrabasinal source similar to the terrigenous framework of the tectonically independent Coniacian-Santonian Ostia Sandstone outcropping southwest of the Cassio Unit. Because of its Cenomanian age the CBS must be considered as a siliciclastic wedge distinct from the younger Ostia Sandstone belonging to the Media Val Taro Unit and time correlative to the Varicoloured Clay of the Cassio Unit. The initiation of the turbidite sandstones terrigenous supply is Cenomanian into the Cassio Basal Complex (CBS), Coniacian into the Media Val Taro Unit (Ostia Sandstone) and Campanian into the more internal Gottero Unit (fine-grained turbidites interbedded within the Val Lavagna Formation). It is proposed that the relative positions of the highest tectonic units outcropping in the Emilian Apennines (i.e. Gottero, Media Val Taro and Cassio Units) during Late Cretaceous were not very different to the present setting, and that their tectono-stratigraphic evolution was related to Alpine-vergent accretionary wedges. The Alpine tectonic polarity should have controlled the westwards migration of the basinal depocentres and the evolution from the Adriatic-margin supply of the Cenomanian turbidites to the European-margin supply of the Maastrichtian turbidites. During the middle Eocene tectonic phase, before the counterclockwise apenninic rotation, the ophiolite-free Cretaceous Ligurian Units (i.e. Gottero, Media Val Taro, Cassio) overthrusted the Ligurian Units characterized by late Cretaceous ophiolitic detritus, known as Ottone and Caio Units, along a significant lithospheric discontinuity which acted as a transpressive fracture zone.&nbsp

    THE GELASIAN STAGE: A PROPOSAL OF A NEW CHRONOSTRATIGRAPHIC UNIT OF THE PLIOCENE SERIES

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    A new Stage, the Gelasian, is proposed as the third upper subdivision of the Pliocene Series. The GSSP of the base of the Gelasian Stage and of the Middle Pliocene-Upper Pliocene boundary is coincident with a "sapropel" level which outcrops in the Monte San Nicola section, near Gela (Southern Sicily, Italy). This level corresponds to the Mediterranean Precessional Related Sapropel 250 of Hilgen (1991)and has an astrochronological age of 2.589 Ma. It correspondes to the oxygen isotopic Stage 103 of Raymo et al.(1989) and in the boundary stratotype section it outcrops 1 meter above the Gauss-Matuyama paleomagnetic boundary. Astrochronologic, magnetostratigraphic, biostratigraphic and climatostratigraphic elements to approximate the GSSP of the Gelasian outside the stratorype section are presented

    Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

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    We present records of stable carbon and oxygen isotopes, CaCO3 content, and changes in calcareous nannofossil assemblages across an 81 m thick section of upper Paleocene lower Eocene marine sedimentary rocks now exposed along the Cicogna Stream in northeast Italy. The studied stratigraphic section represents sediment accumulation in a bathyal hemipelagic setting from approximately 57.5 to 52.2 Ma, a multi-million-year time interval characterized by perturbations in the global carbon cycle and changes in calcareous nannofossil assemblages. The bulk carbonate delta C-13 profile for the Cicogna section, once placed on a common timescale, resembles that at several other locations across the world, and includes both a long-term drop in delta C-13 and multiple short-term carbon isotope excursions (CIEs). This precise correlation of widely separated delta C-13 records in marine sequences results from temporal changes in the carbon composition of the exogenic carbon cycle. However, diagenesis has likely modified the delta C-13 record at Cicogna, an interpretation supported by variations in bulk carbonate 8180, which do not conform to expectations for a primary signal. The record of CaCO3 content reflects a combination of carbonate dilution and dissolution, as also inferred at other sites. Our detailed documentation and statistical analysis of calcareous nannofossil assemblages show major differences before, during and after the Paleocene Eocene Thermal Maximum. Other CIEs in our lower Paleogene section do not exhibit such a distinctive change;instead, these events are sometimes characterized by variations restricted to a limited number of taxa and transient shifts in the relative abundance of primary assemblage components. Both long-lasting and short-lived modifications to calcareous nannofossil assemblages preferentially affected nannoliths or holococcoliths such as Discoaster,, Fasciculithus, Rhomboaster/Tribrachiatus, Sphenolithus and Zygrhablithus, which underwent distinct variations in abundance as well as permanent evolutionary changes in terms of appearances and disappearances. By contrast, placoliths such as Coccolithus and Tow eius, which represent the main component of the assemblages, were characterized by a gradual decline in abundance over time. Comparisons of detailed nannofossil assemblage records at the Cicogna section and at ODP Site 1262 support the idea that variations in the relative and absolute abundances, even some minor changes, were globally synchronous. An obvious link is through climate forcing and carbon cycling, although the linkages between variations in calcareous nannoplankton, changes in delta C-13 records and oceanography will need additional work

    Functional reconstitution of HBV-specific CD8 T cells by in vitro polyphenol treatment in chronic hepatitis B.

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    Background & aims In chronic HBV infection, mitochondrial functions and proteostasis are dysregulated in exhausted HBV-specific CD8 T cells. To better characterise the potential involvement of deregulated protein degradation mechanisms in T cell exhaustion, we analysed lysosome-mediated autophagy in HBV-specific CD8 T cells. Bioactive compounds able to simultaneously target both mitochondrial functions and proteostasis were tested to identify optimal combination strategies to reconstitute efficient antiviral CD8 T cell responses in patients with chronic HBV infection. Methods Lysosome-mediated degradation pathways were analysed by flow cytometry in virus-specific CD8 T cells from patients with chronic HBV infection. Mitochondrial function, intracellular proteostasis, and cytokine production were evaluated in HBV-peptide-stimulated T cell cultures, in the presence or absence of the polyphenols resveratrol (RSV) and oleuropein (OLE) and their metabolites, either alone or in combination with other bioactive compounds. Results HBV-specific CD8 T cells from patients with CHB showed impaired autophagic flux. RSV and OLE elicited a significant improvement in mitochondrial, proteostasis and antiviral functions in CD8 T cells. Cytokine production was also enhanced by synthetic metabolites, which correspond to those generated by RSV and OLE metabolism in vivo, suggesting that these polyphenols may also display an effect after transformation in vivo. Moreover, polyphenolic compounds improved the T cell revitalising effect of mitochondria-targeted antioxidants and of programmed cell death protein 1/programmed cell death ligand 1 blockade. Conclusions Simultaneously targeting multiple altered intracellular pathways with the combination of mitochondria-targeted antioxidants and natural polyphenols may represent a promising immune reconstitution strategy for the treatment of chronic HBV infection. Lay summary In chronic hepatitis B, antiviral T lymphocytes are deeply impaired, with many altered intracellular functions. In vitro exposure to polyphenols, such as resveratrol and oleuropein, can correct some of the deregulated intracellular pathways and improve antiviral T cell function. This effect can be further strengthened by the association of polyphenols with antioxidant compounds in a significant proportion of patients. Thus, the combination of antioxidants and natural polyphenols represents a promising strategy for chronic hepatitis B therapy

    Search for dark Higgsstrahlung in e+ e- -> mu+ mu- and missing energy events with the KLOE experiment

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    We searched for evidence of a Higgsstrahlung process in a secluded sector, leading to a final state with a dark photon U and a dark Higgs boson h', with the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with U decaying into a muon pair and h' producing a missing energy signature. We found no evidence of the process and set upper limits to its parameters in the range 2m_mu<m_U<1000 MeV, m_h'<m_U.Comment: 16 pages, 7 figures, submitted to Physics Letters

    Measurement of the ϕ→π0e+e−\phi \to \pi^0 e^+e^- transition form factor with the KLOE detector

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    A measurement of the vector to pseudoscalar conversion decay ϕ→π0e+e−\phi \to \pi^0 e^+e^- with the KLOE experiment is presented. A sample of ∼9500\sim 9500 signal events was selected from a data set of 1.7 fb−1^{-1} of e+e−e^+e^- collisions at s∼mϕ\sqrt{s} \sim m_{\phi} collected at the DAΦ\PhiNE e+e−e^+e^- collider. These events were used to obtain the first measurement of the transition form factor ∣Fϕπ0(q2)∣| F_{\phi \pi^0}(q^2) | and a new measurement of the branching ratio of the decay: BR (ϕ→π0e+e−)=( 1.35±0.05  −0.10  +0.05 )×10−5\rm{BR}\,(\phi \to \pi^0 e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}. The result improves significantly on previous measurements and is in agreement with theoretical predictions.Comment: 13 pages, 4 figures; matches published versio
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