31 research outputs found
Dating the funerary use of caves in Liguria (northwestern Italy) from the Neolithic to historic times:Results from a large-scale AMS campaign on human skeletal series
The multidisciplinary research team of this new project aimed at the chronological, anthropological and funerary behavior characterization of the skeletal remains unearthed from various caves in western Liguria (northwestern Italy) between the mid-1800s and the 1990s. Most of the burials and scattered bone assemblages were excavated prior to the development of modern stratigraphic methods, or come from disturbed contexts, often resulting in a vague chrono-cultural attribution. We present here the results of a systematic dating project that produced 130 new AMS dates on human bone samples (documented burials or individuals from scattered remains) from sixteen Ligurian caves, including most of the skeletal series from renowned sites such as Arene Candide Cave and Grotta Pollera. Results highlighted the funerary use of these caves from the last quarter of the sixth millennium BCE to the Common Era, with the majority of results clustering in the first half of the fifth millennium BCE. These dates allow for an initial assessment of patterns in Neolithic mortuary use of Ligurian caves, and aided in particular the characterization of funerary practices during the Square Mouthed Pottery culture
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
Reciclagem de materiais: estudo das propriedades mecânicas de policarbonato reciclado de discos compactos
Pulse propagation in a linear and nonlinear diatomic periodic chain: effects of acoustic frequency band-gap
The high affinity melatonin binding site probed with conformationally restricted ligands- I. Pharmacophore and minireceptor models
Serum opacity factor promotes group A streptococcal epithelial cell invasion and virulence
Serum opacity factor (SOF) is a bifunctional cell surface protein expressed by 40-50% of group A streptococcal (GAS) strains comprised of a C-terminal domain that binds fibronectin and an N-terminal domain that mediates opacification of mammalian sera. The sof gene was recently discovered to be cotranscribed in a two-gene operon with a gene encoding another fibronectin-binding protein, sfbX. We compared the ability of a SOF(+) wild-type serotype M49 GAS strain and isogenic mutants lacking SOF or SfbX to invade cultured HEp-2 human pharyngeal epithelial cells. Elimination of SOF led to a significant decrease in HEp-2 intracellular invasion while loss of SfbX had minimal effect. The hypoinvasive phenotype of the SOF(-) mutant could be restored upon complementation with the sof gene on a plasmid vector, and heterologous expression of sof49 in M1 GAS or Lactococcus lactis conferred marked increases in HEp-2 cell invasion. Studies using a mutant sof49 gene lacking the fibronectin-binding domain indicated that the N-terminal opacification domain of SOF contributes to HEp-2 invasion independent of the C-terminal fibronectin binding domain, findings corroborated by observations that a purified SOF N-terminal peptide could promote latex bead adherence to HEp-2 cells and inhibit GAS invasion of HEp-2 cells in a dose-dependent manner. Finally, the first in vivo studies to employ a single gene allelic replacement mutant of SOF demonstrate that this protein contributes to GAS virulence in a murine model of necrotizing skin infection