240 research outputs found
Long-term vs. short-term geochemical changes of Mt. Etna lavas: the puzzling effect of a variegated mantle
Reliability and inter-observer agreement of dermoscopic diagnosis of melanoma and melanocytic naevi
The aim of this study was to analyse the reliability and the inter- observer agreement of dermoscopy in the diagnosis of melanocytic skin lesions. Nine dermatologists, with a different training experience and who routinely used dermoscopy in different hospitals in Italy, evaluated clinical and dermoscopy photographs of 15 melanocytic lesions (four invasive melanomas, four histologically common naevi, and seven naevi with histological atypia). A further series of dermoscopic photographs of 40 melanocytic lesions was evaluated to quantify inter-observer concordance in recognizing dermoscopic criteria. Compared to the true (histological) diagnosis, clinical diagnosis (categories: melanoma, common naevus, atypical naevus) was correct in 40% of cases (range, 27-53%). The percentage raised to 55% (40-73%) by the use of dermoscopy, with an average improvement of 15.6%. Concerning melanoma, clinical diagnosis resulted in a sensitivity of 41.9%, specificity of 77.8%, positive predictive value (PPV) of 36.1%, negative predictive value (NPV) of 81.8%. By using dermoscopy, an improvement of diagnostic performance was found (sensitivity 75%, specificity 88.8%, VPP 71.0%, VPN 90.7%). The inter-observer agreement in melanoma diagnosis, by using dermoscopy, was similar to that obtained by clinical examination (k statistics = 0.54 and 0.52, respectively). Concerning dermoscopic criteria, the best agreement among observers was found for pseudopods, a dermoscopic parameter related to the radial growth phase of melanoma. We conclude that dermoscopy is an useful tool for a non-invasive diagnosis of melanocytic skin lesions, improving the diagnostic performance compared to clinical examination
Petrology of mafic and ultramafic layered rocks from the Jaboncillo Valley, Sierra de Valle Fértil, Argentina: Implications for the evolution of magmas in the lower crust of the Famatinian arc
This work presents the field setting, petrography, mineralogy and geochemistry of a gabbroic and peridotitic layered body that is lens-shaped and surrounded by gabbronorites, diorites, and metasedimentary migmatites. This body exposed at Jaboncillo Valley is one among several examples of mafic and ultramafic layered sequences in the Sierras Valle Fértil and La Huerta, which formed as part of the lower crust of the Ordovician Famatinian magmatic arc in central-western Argentina. The layered sequence grew at deep crustal levels (20–25 km) within a mafic lower crust. The base of the layered body was detached during the tectonic uplift of the Famatinian lower crust, whereas the roof of the layered body is exposed in the eastern zone. In the inferred roof, olivine-bearing rocks vanish, cumulate textures are less frequent, and the igneous sequence becomes dominated by massive or thinly banded gabbronorites. Mainly based on the petrographic relationships, the inferred order of crystallization in the gabbroic and peridotitic layered sequence is: (1) Cr–Al-spinel + olivine, (2) Cr–Al-spinel + olivine + clinopyroxene + magnetite, (3) Cr–Al-spinel + olivine + plagioclase + magnetite ± orthopyroxene, and (4) Al-spinel + orthopyroxene + amphibole. A strong linear negative correlation between olivine and plagioclase modal proportions combined with field, petrographic and geochemical observations are used to demonstrate that the physical separation of olivine and plagioclase results in rock diversity at scales of a few centimeters to tens of meters. However, the composition of olivine (Fo ∼ 0.81) and plagioclase (An > 94%) remains similar throughout the layered sequence. Spinels are restricted to olivine-bearing assemblages, and display chemical trends characteristic of spinels found in arc-related cumulates. Gabbroic and peridotitic layered rocks have trace element concentrations reflecting cumulates of early crystallizing minerals. The trace element patterns still retain the typical features of subduction-related arc magmatism, showing that the process of cumulate formation did not obscure the trace element signature of the parental magma. Using the composition of cumulus minerals and whole-rock chemical trends, we show that the parental magma was mafic (SiO2 ∼ 48 wt.%) with Mg-number around 0.6, and hydrous. The oxygen fugacity (fO2) of the parental magma estimated between +0.8 and −0.6 log fO2 units around the fayalite–magnetite–quartz (FMQ) buffer is also characteristic of primitive hydrous arc magmas. The initially high water content of the parental magma allowed amphibole to crystallize as an interstitial phase all over the crystallization evolution of the layered sequence. Amphibole crystallization in the inter-cumulus assemblage gives rise to the retention of many trace elements which would otherwise be incompatible with the mineral assemblage of mafic–ultramafic cumulates. This study shows that there exist strongly mafic and primitive magmas that are both generated and emplaced within the lower crustal levels of subduction-related magmatic arc. Our findings together with previous studies suggest that the Early Ordovician magmatic paleo-arc from central-northwestern Argentina cannot be regarded as a typical Andean-type tectono-magmatic setting.Fil: Otamendi, Juan Enrique. Universidad Nacional de RÃo Cuarto. Facultad de Ciencias Exactas, FisicoquÃmicas y Naturales. Departamento de GeologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba; ArgentinaFil: Cristofolini, Eber Ariel. Universidad Nacional de RÃo Cuarto. Facultad de Ciencias Exactas, FisicoquÃmicas y Naturales. Departamento de GeologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba; ArgentinaFil: Tibaldi, Alina MarÃa. Universidad Nacional de RÃo Cuarto. Facultad de Ciencias Exactas, FisicoquÃmicas y Naturales. Departamento de GeologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba; ArgentinaFil: Quevedo, F. I.. Universidad Nacional de RÃo Cuarto. Facultad de Ciencias Exactas, FisicoquÃmicas y Naturales. Departamento de GeologÃa; ArgentinaFil: Baliani Cocitto, Ignacio. Universidad Nacional de RÃo Cuarto. Facultad de Ciencias Exactas, FisicoquÃmicas y Naturales. Departamento de GeologÃa; Argentin
Apoptosis and cell proliferation in porcine placental vascularization
The placenta is a highly vascularized organ, indispensable tothe transfer of nutrients to the growing fetuses. During gestation, there exists an expansion of the placental vascular network through active angiogenesis. The aim of this research was to study cell proliferation and apoptosis through high resolution light microscopy (HRLM) and transmission electron microscopy (TEM) ultrastructure, immunohistochemistry for Ki67and caspase-3, determination of placental vascular area,and TUNEL assay. Crossbred sows placental tissues from approximately 30 ± 2(n =5), 40 ± 2(n =5), 60 ± 2 (n =5), 80 ± 2(n =5), 90 ± 2(n =5) and 114 ± 2(n =5) days of gestation were used. The evaluation of cell proliferation showed the highest%Ki67 values on days 30 ± 2 and 80 ± 2 of pregnancy. Caspase-3 expressed the highest value on day 30 ± 2, while the highest apoptotic indexes were found on days30 ± 2 and 90 ± 2. The placental vascular area was higher on day 80 ± 2 of pregnancy. According to our results, an active vascular cell remodeling by a caspase-3 dependent apoptosis seems to be present in early pregnancy. The increase in the vascular area on day 80 ± 2 would be the result of the intense vascular cell proliferation detected with Ki67. Further studies are needed to understand the complex processes of angiogenesis, cell proliferation and apoptosis that interact in the placenta during porcine gestation.Facultad de Ciencias Veterinaria
Studio della resistenza alla fatica di contatto di acciai sinterizzati trattati termicamente
In questo studio viene proposto un approccio conservativo per la previsione del comportamento a fatica dicontatto di due acciai sinterizzati e trattati termicamente. Il modello utilizzato è incentrato sulla nucleazionedella cricca di fatica, che avviene solamente in presenza di fenomeni di deformazione plastica locale. Ladeformazione plastica locale, a sua volta, si verifica quando lo sforzo massimo è superiore alla resistenza allosnervamento del materiale negli strati subsuperficiali. Sforzo massimo e resistenza alla deformazione plasticasono stati calcolati considerando le peculiarità della microstruttura dei sinterizzati porosi: la distribuzionedella dimensione e del fattore di forma dei pori, che influenzano la frazione di sezione utile resistente, el’eterogeneità microstrutturale e della microdurezza, che influenzano la resistenza allo snervamento dellamatrice. Il modello previsionale è stato validato sperimentalmente
Expresión de VEGFA y VEGFR2 en la placenta de cerdos en los 75 y 85 dÃas de gestación
En el cerdo, la gestación dura aproximadamente 114 dÃas y la placenta es epiteliocorial, no invasiva, difusa, plegada y adecidua. Durante el desarrollo placentario, ocurre un proceso fundamental denominado angiogénesis, el cual consiste en la formación de vasos sanguÃneos a partir de vasos preexistentes. Este proceso depende de la expresión de factores angiogénicos, como el factor de crecimiento endotelio vascular (VEGFA), una proteÃna secretada por las células de la pared de los vasos sanguÃneos, que actúa mediante la unión a VEGFR2 promoviendo la permeabilidad vascular, la proliferación y la migración de células endoteliales para la formación de vasos sanguÃneos. El objetivo de este trabajo fue determinar la inmunoexpresión de VEGFA y su receptor VEGFR2 en placentas porcinas pretérmino, en los dÃas 75 y 85 de gestación.Facultad de Ciencias Veterinaria
Wave vector dependence of the dynamics in supercooled metallic liquids
We present a detailed investigation of the wave vector dependence of
collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21
supercooled liquids close to the glass transition temperature. Using x-ray
photon correlation spectroscopy in a precedent uncovered spatial range of only
few interatomic distances, we show that the microscopic structural relaxation
process follows in phase the structure with a marked slowing down at the main
average inter-particle distance. This behavior is accompanied by dramatic
changes in the shape of the intermediate scattering functions which suggest the
presence of large dynamical heterogeneities at length-scales corresponding to
few particle diameters. A ballistic-like mechanism of particle motion seems to
govern the structural relaxation of the two systems in the highly viscous
phase, likely associated to hopping of caged particles in agreement with
theoretical studies
The role of product feature relations in a knowledge based methodology to manage design modifications for product measurability
In vitro analysis of the influence of surface treatment of dental implants on primary stability
- …