102,124 research outputs found
Identification of vegetal plant species from colour and pattern analysis of drone images
No full textRe-equilibration of detrital muscovite and the formation of interleaved phyllosilicate grains in low temperature metamorphism, northern Apennines, Italy
No full textAlbert Memmi, Tunisie An I, édité et annoté par Guy Dugas, in PONTS/PONTI , Milano - Udine, Mimesis, 2018
No full textLa recensione presenta il diario intimo - curato e pubblicato da G. Dugas - dello scrittore tunisino Albert Memmi di ritorno al paese natale subito dopo l'Indipendenza
Integrated XRD and EMPA studies on Millen Schist in the Bowers Mountains, northern Victoria Land, Antarctica
No full textI materiali vitrei di Herdonia (Foggia, Italia): studi di caratterizzazione e ipotesi di provenienza
No full textThe sample set from the cistern of the domus B consists of 21 glass sherds (cups, lamps, glasses/lamps, goblets, jugs/bottles,
unidentified typologies) and 4 production wastes dated to the first half of the 5th century A.D. They are characterised by various
shades of colour (yellow, olive-green, green-yellow, yellow-red, blue-green, blue, green, light and dark green), but colourless
glass is also represented. Samples were analysed by optical microscopy (MO), scanning electron microscopy (SEM-EDS),
electron Probe Micro Analysis (EPMA), X-ray fluorescence (XRF), inductively coupled plasma optical emission spectrometry
(ICP-OES), inductively coupled plasma mass spectrometry (ICP–MS) and instrumental neutron activation analysis (INAA) in
order to characterise both the texture and composition of glasses, and to identify vitrifying, stabilizing, flushing and colouring
agents. Our data were compared with those available in the literature in order to investigate the provenance of materials.
All finished products were produced from a mixture of siliceous sand and natron; however, they can be divided into GROUP A,
comprising yellow, olive-green and green-yellow glasses, and GROUP B, represented by yellow-red, colourless, blue-green,
light green and blue glasses. GROUP A is characterised by lower SiO2, K2O and CaO contents and higher Na2O and MgO contents
than GROUP B, suggesting a different source of sand and a different recipe. Furthermore, Sr and Zr contents seem to
indicate for GROUP A the use of shell and a different sand from that of the Levantine coast, while for GROUP B the employment
of a Levantine sand rich in shell. The colour of the artefacts is probably due to both the Fe3+/Fe2+ ratio and Fe2O3 and MnO
contents, but further studies on the oxidation state of Fe will be necessary to clarify the question. Unfinished products were produced
from natron and a siliceous sand and have an intermediate composition with respect to GROUPS A and B, even if more
similar to GROUP B. Flushing contents indicate a Na2O-richer recipe or shorter production cycle with respect to finished products.
As for colorants, the considerations relative to the finished products are also valid for unfinished products.
As for the provenance of materials, GROUP A shows analogies with glasses included in the HIMT group (Carthage,
Cyprus) of unknown origin. The composition of GROUP B samples is similar to that of Levantine glasses, suggesting an
import of raw glass or artefacts from the Syro-Palestinian coast. They were apparently produced from Belus sand mixed
with natron. Lastly, although the provenance of unfinished products is unclear, they are compositionally similar to the
glasses produced from natron and Belus sand
Multi-stage metamorphic re-equilibration in eclogitic rocks from the Hercynian basement of NE Sardinia, Italy
No full textEclogitic rocks are hosted within gneisses and migmatites of the Hercynian basement of NE Sardinia. They are characterized by two compositional layers: garnet-pyroxene rich-layers and amphibole-plagioclase layers. The former contain structural, mineralogical and compositional relics of eclogite facies re-equilibration. Four stages of evolution have been identified: an eclogite stage, a granulite stage and a retrograde amphibolite to greenschist stage. A possible pre(?)-eclogite stage is documented by inclusions of euhedral tschermakitic amphibole + zoisite within the core of garnet. This early stage was followed by an increase in pressure under which the eclogite climax developed (T up to 700 °C, P = 13-15 kbar), as documented by omphacite inclusions towards the rim of garnet. Characteristic mineral reactions after the eclogitic stage are: omphacite → diopside + plagioclase (symplectite) and garnet → orthopyroxene + plagioclase. These reactions testify the presence of a granulite stage during which the peak of metamorphism was reached (T up to 870 °C, P ≈10 kbar). The orthopyroxene → cummingtonite + quartz and garnet + diopside → hornblende + plagioclase (kelyphite) transformations indicate extensive amphibolite retrogression (T = 550-650 °C, P = 3-7 kbar). Finally, actinolite and chlorite developed (greenschist stage) at falling temperature and pressure (T = 300-400 °C, P < 2-3 kbar)
Integrated XRD and EMPA studies of Millen Schists in the Bowers Mountains, northern Victoria Land, Antarctica
No full textThe Faragola Ceramic Collection: Ceramic Production, Consumption and Exchange in Seventh-Century Apulia
No full textA collection of 30 ceramic samples, 16 of coarse wares and 14 of fine painted wares, have been investigated by optical microscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry and neutron activation analysis. Further samples of clayey sediments, both locally outcropping and found within the settling tank, have been submitted to the same analytical techniques for comparison with the ceramic collection. The results demonstrated that local clayey sediments were used as received for the production of coarse wares. The same raw materials were sieved and/or refined by decantation for the production of fine painted wares, which, in fact, provided results that were perfectly comparable with those for the clayey raw materials found within the settling tank. The Faragola productions were distinguished from the neighbouring Apulian productions according to petrographic features (the presence of leucite-bearing volcanic rocks and Mn-rich wads) and their bulk chemical composition. © 2013 University of Oxford
Further illite crystallinity data from Bowers Terrane, Millen Schists and Robertson Bay Terrane (northern Victoria Land, Antarctica)
No full textThis paper provides new data on the regional relationships between Bowers and Robertson Bay terranes, two main units of Ross age in the northern Victoria Land sector of the Transantarctic Mountains. This contribution aims to complete the regional investigation by surveying areas never or only partly visited and sampled during the scientific expeditions in the last fifteen years. The analysed samples were collected from the Bowers Mountains and the Robinson Heights. The data deal with the illite crystallinity index (IC) values of very low- to low-grade metamorphic rocks from both the Bowers and Robertson Bay terranes, and the intervening Millen Schist belt. The obtained results confirm the already known regional setting. All the IC data are comparable and may be related to the epizone; anyway, the IC average values from the three tectonic complexes show slight differences. Comparison of these differences with petrographic observations (original on the same samples or retrieved from literature) points to a slightly higher metamorphic imprinting (coeval with more severe deformation) of the Millen Schist with respect to the Bowers and Robertson Bay rocks
LuxS impacts on LytA-dependent autolysis and on competence in Streptococcus pneumoniae
No full textThe ubiquitous protein LuxS with S-ribosylhomocysteinase activity is involved in S-adenosyl methionine detoxification, C-1 unit recycling and the production of autoinducers that allow the cell to sense and respond to cell density. Independent reports describe the impact of LuxS deficiency on Streptococcus pneumoniae virulence in the mouse. In vitro, LuxS deficiency confers discrete phenotypes. A combined approach using genetic dissection and mixed-culture experiments allowed the involvement of LuxS in the developmental physiology of S. pneumoniae to be investigated. Functional LuxS was found to be related on the one hand to down-regulation of competence, and on the other hand to attenuation of autolysis in cultures entering stationary phase. The competence phenotype of luxS mutant bacteria was complemented by media conditioned by competence-defective ComAB0 bacteria, but not by BSA. The autolytic phenotype was complemented by BSA, but not by conditioned supernatants. It is suggested that the impact of LuxS on competence, but not on autolysis, involves cell-cell communication. The phenotype of luxS mutant strains reveals a hierarchy in the competence regulatory networks of S. pneumoniae
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