1,958 research outputs found
Suitable classification of mortars from ancient roman and renaissance frescoes using thermal analysis and chemometrics
Background
Literature on mortars has mainly focused on the identification and characterization of their components in order to assign them to a specific historical period, after accurate classification. For this purpose, different analytical techniques have been proposed. Aim of the present study was to verify whether the combination of thermal analysis and chemometric methods could be used to obtain a fast but correct classification of ancient mortar samples of different ages (Roman era and Renaissance).
Results
Ancient Roman frescoes from Museo Nazionale Romano (Terme di Diocleziano, Rome, Italy) and Renaissance frescoes from Sistine Chapel and Old Vatican Rooms (Vatican City) were analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Principal Component analysis (PCA) on the main thermal data evidenced the presence of two clusters, ascribable to the two different ages. Inspection of the loadings allowed to interpret the observed differences in terms of the experimental variables.
Conclusions
PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones. It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out
Temporal condensed matter physics in gas-filled photonic crystal fibers
Raman effect in gases can generate an extremely long-living wave of coherence
that can lead to the establishment of an almost perfect periodic variation of
the medium refractive index. We show theoretically and numerically that the
equations, regulate the pulse propagation in hollow-core photonic crystal
fibers filled by Raman-active gas, are exactly identical to a classical problem
in quantum condensed matter physics -- but with the role of space and time
reversed -- namely an electron in a periodic potential subject to a constant
electric field. We are therefore able to infer the existence of Wannier-Stark
ladders, Bloch oscillations, and Zener tunneling, phenomena that are normally
associated with condensed matter physics only, now realized with purely optical
means in the temporal domain
Raman-induced temporal condensed matter physics in gas-filled photonic crystal fibers
Raman effect in gases can generate an extremely long-living wave of coherence that can lead to the establishment of an almost perfect temporal periodic variation of the medium refractive index. We show theoretically and numerically that the equations, regulate the pulse propagation in hollow-core photonic crystal fibers filled by Raman-active gas, are exactly identical to a classical problem in quantum condensed matter physics - but with the role of space and time reversed - namely an electron in a periodic potential subject to a constant electric field. We are therefore able to infer the existence of Wannier-Stark ladders, Bloch oscillations, and Zener tunneling, phenomena that are normally associated with condensed matter physics, using purely optical means. (C) 2015 Optical Society of Americ
Integrated geophysical survey in a sinkhole-prone area: Microgravity, electrical resistivity tomographies, and seismic noise measurements to delimit its extension
Real Time Marine Data Acquisition: The Coastal Oceanographic Observatory Network in the Adriatic sea.
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Coarsening and Pinning in the Self-consistent Solution of Polymer Blends Phase-Separation Kinetics
We study analytically a continuum model for phase-separation in binary
polymer blends based on the Flory-Huggins-De Gennes free energy, by means of
the self-consistent large- limit approach. The model is solved for values of
the parameters corresponding to the weak and strong segregation limits. For
deep quenches we identify a complex structure of intermediate regimes and
crossovers characterized by the existence of a time domain such that phase
separation is pinned, followed by a preasymptotic regime which in the scalar
case corresponds to surface diffusion. The duration of the pinning is
analytically computed and diverges in the strong segregation limit. Eventually
a late stage dynamics sets in, described by scaling laws and exponents
analogous to those of the corresponding small molecule systems.Comment: 16 pages, 5 figures. Submitted to Phys. Rev.
IL-17+ CD8+ T cell suppression by dimethyl fumarate associates with clinical response in multiple sclerosis
IL-17-producing CD8+ (Tc17) cells are enriched in active lesions of patients with multiple sclerosis (MS), suggesting a role in the pathogenesis of autoimmunity. Here we show that amelioration of MS by dimethyl fumarate (DMF), a mechanistically elusive drug, associates with suppression of Tc17 cells. DMF treatment results in reduced frequency of Tc17, contrary to Th17 cells, and in a decreased ratio of the regulators RORC-to-TBX21, along with a shift towards cytotoxic T lymphocyte gene expression signature in CD8+ T cells from MS patients. Mechanistically, DMF potentiates the PI3K-AKT-FOXO1-T-BET pathway, thereby limiting IL-17 and RORγt expression as well as STAT5-signaling in a glutathione-dependent manner. This results in chromatin remodeling at the Il17 locus. Consequently, T-BET-deficiency in mice or inhibition of PI3K-AKT, STAT5 or reactive oxygen species prevents DMF-mediated Tc17 suppression. Overall, our data disclose a DMF-AKT-T-BET driven immune modulation and suggest putative therapy targets in MS and beyond
Three-row versus two-row circular staplers for left-sided colorectal anastomosis: a propensity score-matched analysis of the iCral 2 and 3 prospective cohorts
Background: Since most anastomoses after left-sided colorectal resections are performed with a circular stapler, any technological change in stapling devices may influence the incidence of anastomotic adverse events. The aim of the present study was to analyze the effect of a three-row circular stapler on anastomotic leakage and related morbidity after left-sided colorectal resections. Materials and methods: A circular stapled anastomosis was performed in 4255 (50.9%) out of 8359 patients enrolled in two prospective multicenter studies in Italy, and, after exclusion criteria to reduce heterogeneity, 2799 (65.8%) cases were retrospectively analyzed through a 1:1 propensity score-matching model including 20 covariates relative to patient characteristics, to surgery and to perioperative management. Two well-balanced groups of 425 patients each were obtained: group (A) – true population of interest, anastomosis performed with a three-row circular stapler; group (B) – control population, anastomosis performed with a two-row circular stapler. The target of inferences was the average treatment effect in the treated (ATT). The primary endpoints were overall and major anastomotic leakage and overall anastomotic bleeding; the secondary endpoints were overall and major morbidity and mortality rates. The results of multiple logistic regression analyses for the outcomes, including the 20 covariates selected for matching, were presented as odds ratios (OR) and 95% confidence intervals (95% CI). Results: Group A versus group B showed a significantly lower risk of overall anastomotic leakage (2.1 vs. 6.1%; OR 0.33; 95% CI 0.15–0.73; P = 0.006), major anastomotic leakage (2.1 vs. 5.2%; OR 0.39; 95% CI 0.17–0.87; P = 0.022), and major morbidity (3.5 vs. 6.6% events; OR 0.47; 95% CI 0.24–0.91; P = 0.026). Conclusion: The use of three-row circular staplers independently reduced the risk of anastomotic leakage and related morbidity after left-sided colorectal resection. Twenty-five patients were required to avoid one leakage
Genome-wide association analysis of genetic generalized epilepsies implicates susceptibility loci at 1q43, 2p16.1, 2q22.3 and 17q21.32
Genetic generalized epilepsies (GGEs) have a lifetime prevalence of 0.3% and account for 20-30% of all epilepsies. Despite their high heritability of 80%, the genetic factors predisposing to GGEs remain elusive. To identify susceptibility variants shared across common GGE syndromes, we carried out a two-stage genome-wide association study (GWAS) including 3020 patients with GGEs and 3954 controls of European ancestry. To dissect out syndrome-related variants, we also explored two distinct GGE subgroups comprising 1434 patients with genetic absence epilepsies (GAEs) and 1134 patients with juvenile myoclonic epilepsy (JME). Joint Stage-1 and 2 analyses revealed genome-wide significant associations for GGEs at 2p16.1 (rs13026414, Pmeta = 2.5 × 10−9, OR[T] = 0.81) and 17q21.32 (rs72823592, Pmeta = 9.3 × 10−9, OR[A] = 0.77). The search for syndrome-related susceptibility alleles identified significant associations for GAEs at 2q22.3 (rs10496964, Pmeta = 9.1 × 10−9, OR[T] = 0.68) and at 1q43 for JME (rs12059546, Pmeta = 4.1 × 10−8, OR[G] = 1.42). Suggestive evidence for an association with GGEs was found in the region 2q24.3 (rs11890028, Pmeta = 4.0 × 10−6) nearby the SCN1A gene, which is currently the gene with the largest number of known epilepsy-related mutations. The associated regions harbor high-ranking candidate genes: CHRM3 at 1q43, VRK2 at 2p16.1, ZEB2 at 2q22.3, SCN1A at 2q24.3 and PNPO at 17q21.32. Further replication efforts are necessary to elucidate whether these positional candidate genes contribute to the heritability of the common GGE syndrome
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