336 research outputs found
Computed Tomography of the Coronary Arteries
MSCT Coronary Angiography is a fast developing non-invasive diagnostic technique that can detect a coronary stenosis. The detection of a coronary stenosis is hampered by limited image quality and by motion artefacts and extensive calcifications. However, MSCT-coronary angiography is highly reliable to rule out coronary stenosis. The role of MSCT-coronary angiography in the diagnostic work-up of coronary artery disease needs further research
Archaeometric Study of Two Tanagra Type Statuettes of Unknown Provenance to Support Forensic Study
This paper is concerned with a morphological-stylistic and archaeometric study of two small pottery statues, confiscated by the Cosenza Carabinieri Unit for the Protection of Cultural Heritage and Anti-Counterfeiting (Calabria, Italy). The research aimed to establish the authenticity of the artworks and to verify a possible origin from the same workshop manufacturing, by providing indications about the textural features and raw materials used for their production. For these purposes, the analytical approach involved the use of minero-petrographic and physical analysis, as follows: petrographic analysis (OM), X-ray diffraction (XRD) and thermoluminescence tests (TL). The preliminary observation, which highlights differences in the stylistic features of the two statuettes as well as in the color, morphology and distribution of the white-greyish patina, is further confirmed by the TL investigations. The TL test revealed an ancient production only for one of the analyzed finds and the investigations on the raw materials allowed to relate this to a possible local historical-artistic context. The second statuette, on the other hand, is attributable to a modern production as confirmed by TL measurement
Comparative analysis for the assessment of restoration treatments on stone material from the roman theater of Merida (Spain)
The overall goal of the project is the study of effects of conservation treatments
applied
on
stone material from archaeological sites, i
n terms of superficial changes, effectiveness and
durability. In this sense, one of the first premises is characterize the surface of the treated and
untreated material in order to determine changes in physical and chemical properties
Byzantine wall paintings from San Marco d’Alunzio, Sicily: non-invasive diagnostics and microanalytical investigation of pigments and plasters
A diagnostic investigation was carried out on twelfth century Byzantine wall paintings preserved in the Museum of Byzantine and Norman Culture and Figurative Arts of San Marco d’Alunzio (Messina, Italy) on the occasion of recent restoration works. First, the wall paintings were analyzed using portable X-Ray Fluorescence (p-XRF) and Fiber Optics Reflectance Spectroscopy (FORS) to obtain a non-invasive preliminary identification of the original palette. Then, five
fragments were sampled for a micro-stratigraphy study using Digital Optical Microscope (DOM), Polarizing Optical Microscope (POM), and Scanning Electron Microscopy (SEM) combined with Energy Dispersive X-ray Spectrometry
(EDS) to characterize the mortars and the blue and black pigments non unequivocally identified through non-invasive techniques. The palette included mainly earthen pigments like red and yellow ochres, green earth, and more valuable lapis lazuli blue applied on a bone black layer; while the analysis of mortars found on the different apses showed the same manufacturing technique and constitutive materials: lime-based binder with the addition of quartz, and rare
calcareous lithic fragments as aggregate. The obtained results shed light on the pictorial technique used for the wall paintings and allowed us to compare the Sicilian pictorial cycle with the coeval Byzantine wall paintings preserved
in Sardinia and Southern Italy
Two stucco sculptures from the “Salone d'Ercole” in the Racconigi Castle (Cuneo, Italy): a case study
Non-invasive and micro-destructive diagnostic investigations were employed for the study of two stucco statues depicting Putti, from the “Salone d’Ercole” in the Racconigi Castle (Cuneo, Italy). The research made it possible to understand the construction technique, constituent materials, and the state of conservation of the statues. This information was useful for placing the artworks in the correct historical-artistic context and for conservation choices and restoration interventions. Different analytical investigations were applied, specifically: a) the internal metal structure was analyzed by cover meter relief combined with digital radiographic technique; b) the stucco composition and its stratigraphy were characterized by Polarized Optical Microscopy (POM), X-ray diffraction (XRD) and Electron Scanning Microscopy coupled with Energy-
Dispersive X-ray spectroscopy (SEM-EDX); c) finally, the presence of organic compounds was observed by UV-Induced Visible Fluorescence (UVL) and then characterized by Fourier Transform Infrared Spectroscopy (FT-IR) analyses. The results show that the stucco Putti were made with the techniques and raw materials widely used by Ticino artists and plasterers’ workshops active between the 16th and 17th centuries, in the current Canton Ticino region. As regards the state of conservation, decay phenomena such as exfoliation and loss of material were mainly attributable to the presence of epsomite
A tale of swinger insects: signatures of past sexuality between divergent lineages of a parthenogenetic weevil revealed by ribosomal intraindividual variation
Naupactus cervinus (Boheman) (Curculionidae, Naupactini) is a parthenogenetic weevil native to the Paranaense Forest which displays high levels of genetic variation. Two divergent clades were identified, one ranging in forest areas (Forest clade), and the other in open vegetation areas (Grassland clade). Both of them have individuals with high levels of heterozygosity in ribosomal sequences. Investigation of intraindividual variation in ITS1 sequences through cloning and posterior sequencing suggested that mating between both groups most likely occurred in the Paranaense Forest after a secondary contact, which led to fixed heterozygotes as a consequence of parthenogenesis. Otherwise, sexual segregation would have disrupted multilocus genotypes. Only a small number of heterozygous genotypes of all the possible combinations are found in nature. We propose the occurrence of a hybrid zone in the Paranaense Forest. The fact that it is one of the most important biodiversity hotspots of the world, together with its key role for investigating evolutionary processes, makes it worthy of conservation. This is the first genetic evidence of bisexuality in N. cervinus.Facultad de Ciencias Naturales y Muse
RNA:protein ratio of the unicellular organism as a characteristic of phosphorous and nitrogen stoichiometry and of the cellular requirement of ribosomes for protein synthesis
Background
Mean phosphorous:nitrogen (P:N) ratios and relationships of P:N ratios with the growth rate of organisms indicate a surprising similarity among and within microbial species, plants, and insect herbivores. To reveal the cellular mechanisms underling this similarity, the macromolecular composition of seven microorganisms and the effect of specific growth rate (SGR) on RNA:protein ratio, the number of ribosomes, and peptide elongation rate (PER) were analyzed under different conditions of exponential growth.
Results
It was found that P:N ratios calculated from RNA and protein contents in these particular organisms were in the same range as the mean ratios reported for diverse organisms and had similar positive relationships with growth rate, consistent with the growth-rate hypothesis. The efficiency of protein synthesis in microorganisms is estimated as the number of active ribosomes required for the incorporation of one amino acid into the synthesized protein. This parameter is calculated as the SGR:PER ratio. Experimental and theoretical evidence indicated that the requirement of ribosomes for protein synthesis is proportional to the RNA:protein ratio. The constant of proportionality had the same values for all organisms, and was derived mechanistically from the characteristics of the protein-synthesis machinery of the cell (the number of nucleotides per ribosome, the average masses of nucleotides and amino acids, the fraction of ribosomal RNA in the total RNA, and the fraction of active ribosomes). Impairment of the growth conditions decreased the RNA:protein ratio and increased the overall efficiency of protein synthesis in the microorganisms.
Conclusion
Our results suggest that the decrease in RNA:protein and estimated P:N ratios with decrease in the growth rate of the microorganism is a consequence of an increased overall efficiency of protein synthesis in the cell resulting from activation of the general stress response and increased transcription of cellular maintenance genes at the expense of growth related genes. The strong link between P:N stoichiometry, RNA:protein ratio, ribosomal requirement for protein synthesis, and growth rate of microorganisms indicated by the study could be used to characterize the N and P economy of complex ecosystems such as soils and the oceans
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