Las terrazas del río Miño en el tramo Chantada-As Neves (límite de Galicia-Portugal)

Geomorphologic mapping is specially difficult in areas with scarce deposits of uncertain chronology and with multiage and multiorigin forms. This is the case of Galicia. This paper is an attempt to reconstruct the geomorphologic history of Galicia during the Cenozoic in an area especially relevant because of its geodynamic situation. It has been made an exhaustive inventory of the erosive and accumulation terrace levels in a specific section of the Miño, the main river course of the region. Here it is presented the terrace levels list between Chantada and As Neves, their relation to the three etched surfaces R800, R600 and R400, wich are the most relevant because of their areal extent. It is also analyzed their relationship with the longitudinal profile of the river. Using the only existing criteria, i.e., topographic continuity and altitude, it is proposed an evolutionary model substantially determined by the river incision associated with the Paleogene collision among the Euro-Asian and the Iberian Plates. This process geomorphologically begun after the generation of R600 surface which is equivalent in Galicia to the Peninsular Fundamental Surface

Comparison of the internalization efficiency of LDL and transferrin receptors on L2C guinea pig lymphocytes

AbstractWe demonstrate that L2C lymphocytes have about 10-times more receptors for transferrin (TO than healthy lymphocytes, as has been shown in the case of LDL receptors. The dissociation constant is the same in the two cell types (about 4 × 10−7 M). In contrast to LDL, Tf enters L2C lymphocytes with very rapid kinetics. It is shown by cross-reaction that each receptor is internalized independently of the other

Detection, size characterization and quantification of silver nanoparticles in consumer products by particle collision coulometry

Silver nanoparticles (AgNPs) are widely used in industrial and consumer products owing to its antimicrobial nature and multiple applications. Consequently, their release into the environment is becoming a big concern because of their negative impacts on living organisms. In this work, AgNPs were detected at a potential of + 0.70 V vs. Ag/AgCl reference electrode, characterized, and quantified in consumer products by particle collision coulometry (PCC). The electrochemical results were compared with those measured with electron microscopy and single-particle inductively coupled plasma mass spectrometry. The theoretical and practical peculiarities of the application of PCC technique in the characterization of AgNPs were studied. Reproducible size distributions of the AgNPs were measured in a range 10–100 nm diameters. A power allometric function model was found between the frequency of the AgNPs collisions onto the electrode surface and the number concentration of nanoparticles up to a silver concentration of 1010 L-1 (ca. 25 ng L-1 for 10 nm AgNPs). A linear relationship between the number of collisions and the number concentration of silver nanoparticles was observed up to 5 × 107 L-1. The PCC method was applied to the quantification and size determination of the AgNPs in three-silver containing consumer products (a natural antibiotic and two food supplements). The mean of the size distributions (of the order 10–20 nm diameters) agrees with those measured by electron microscopy. Graphical abstract: [Figure not available: see fulltext.]

Geoquímica del extenso depósito de flujo piroclástico hiperalcalino del NW de México, basada en fluorescencia de rayos X convencional y portátil. Implicaciones en un contexto regional

Chemical analyses conducted on the surface of rock slabs under a combination of two X-ray spectrometry methods, wavelength dispersive XRF and energy dispersive XRF, are used to establish a geochemical correlation between the studied samples. This proves to be an excellent method for the characterization of volcanic glasses, particularly when particles of exotic origin are present, because the effect of these is not easily eliminated by conventional whole rock analysis. Analyses of glassy rhyolites (ignimbrites and lava flows) in northwestern Mexico establish a geochemical signature for the samples, providing criteria that allow us to: a) correlate them with a peralkaline volcanic event, previously reported, that occurred during Middle Miocene time; b) distinguish them from other metaluminous varieties in the region and, c) propose a correlation between all the peralkaline vitrophyres that crop out within the studied area, of at least 50.000 km2, validating the hypothesis that they are related to the same volcanic event. Finally, based on the results of this study and previous geological investigations, it is proposed that a distance of more than 100 km between the geographical location of the thickest peralkaline deposits in Sonora, is probably related to a displacement along transtensional dextral faults during the Late Miocene.El análisis químico realizado en secciones de roca bajo la combinación de dos métodos de espectrometría de fluorescencia de rayos x, por dispersión de longitudes de onda y por dispersión de energías, permitió establecer una correlación geoquímica entre las muestras estudiadas, resultando ser un excelente método para la caracterización de vidrios volcánicos, en particular cuando contienen partículas ajenas al magma que no pueden ser eliminadas por el análisis de roca total convencional. Los resultados obtenidos sobre las riolitas vítreas estudiadas (ignimbritas y coladas) del Noroeste de México permiten establecer una firma geoquímica de las muestras que proporciona criterios permitiendo: a) correlacionarlas con un evento volcánico, anteriormente descrito, de tipo hiperalcalino que ocurrió durante el Mioceno medio; b) diferenciarlas de las ignimbritas metaluminosas también presentes en la región y, c) proponer una correlación entre los vitrófiros de la zona estudiada, de al menos 50000 km2, haciendo válida la hipótesis de que todos ellos provienen de una misma erupción. Finalmente, basados en los resultados de este estudio y de trabajos geológicos previos, se propone que una diferencia de hasta más de 100 km en la ubicación geográfica de los depósitos hiperalcalinos de mayor espesor, es probablemente relacionada con un desplazamiento a lo largo de fallas dextrales asociadas a un evento extensivo en transtensión ocurrido durante el Mioceno superior

Geochemical and geochronological constraints on the geologic evolution of the western Sonobari Complex, northwestern Mexico

In the southern Sierra Sonobari, NW Mexico, U-Pb and 40Ar/39Ar geochronology studies allowed to define the provenance and maximum depositional age of the Francisco Gneiss basement of the Sonobari terrane, and to establish the age of some magmatic events in that area. The youngest zircon cluster in paragneisses of the Francisco Gneiss indicates a maximum depositional age of 509 ± 29Ma. The main peaks of the relative probability plot yield ages of 1690 and 1404Ma with minor peaks at 1156, 921, and 517Ma. Major peaks suggest that the main source of sediments was the Paleo- and Mesoproterozoic crust of Laurentia. Orthogneiss from the Francisco Gneiss yields a U-Pb zircon upper intercept age of 248 ± 28Ma, which is interpreted as the crystallization age. Crosscutting dykes of metabasite yield an 40Ar/39Ar age of 67 ± 5Ma, which is interpreted as indicating cooling after either a latest Early Cretaceous orogenic event or Late Cretaceous contact metamorphism. Granodiorite intruding the Francisco Gneiss yields a U-Pb age of 64 ± 1Ma, which is interpreted as a magmatic age. The hornblende-plagioclase Macochin Gabbro yields 40Ar/39Ar isochron ages of 54 ± 10Ma and 47 ± 5Ma, which are interpreted as cooling ages after the gabbro intrusion. Geochemical data indicate that the mafic rocks of the Francisco Gneiss correspond to subalkaline basalts of tholeiitic affinity with concentrations of high field strength elements similar to oceanic basalts, suggesting an asthenospheric upper mantle source. However, according to the variation in Th/Yb and U/Yb, the amphibolites display a significant influence of the upper continental crust. The Macochin Gabbro also has a geochemical signature characteristic of subalkaline basalt with tholeiitic affinity, and high field strength elements similar to oceanic basalts. Tectonic discrimination diagrams and elemental distribution suggest that the mafic rocks of both the Francisco Gneiss and Macochin Gabbro were emplaced during rifting in a back-arc setting

Post-depositional processes of elemental enrichment inside dark nodular masses of an ancient aeolian dune from A Coruña, Northwest Spain

This paper focuses on a residual ancient aeolian climbing dune from Punta Penaboa (A Coruña, Northwest Spain) showing evidence of post-depositional weathering, particularly the presence of dark brown nodular masses. The partitioning of trace elements between nodular masses and host sand during post-depositional weathering of the dune is investigated in this work, with the main objective of studying the elemental enrichment patterns in the dark masses. Data of the concentrations of chemical elements were obtained by instrumental neutron activation analysis (INAA) and complemented by mineralogical and microchemical studies, using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) / energy dispersive X-ray spectrometry (EDS). The dune was dated by optically stimulated luminescence (OSL) , yielding an age of 300ka B.P.. The dark nodular masses preserved the dune sand structure, without defined concentric layers, suggesting an early stage of formation. They consist mainly of quartz grains cemented by clay materials enriched in the majority of the elements studied, especially in Mn, Co, Ba, Sb, Ce, Tb, Th, As, Zr and Hf. The post-depositional transformations of the dune were most likely influenced by migration of chemical compounds from the surrounding slope deposits and granitic rocks, as well as microbial activity that promoted metals concentration in the solutions percolating through the pore network of the dune. Seasonal changes in the redox potential were required to produce the accumulation of Mn and other trace elements in the dune pore network and to promote the fractionation between Ce4+ and trivalent rare earth elements that was observed in the geochemical patterns

Application of Model-driven engineering to multi-agent systems: a language to model behaviors of reactive agents

Many users of multi-agent systems (MAS) are very commonly disinclined to model and simulate using current MAS platforms. More specifically, modeling the dynamics of a system (in particular the agents' behaviors) is very often a challenge to MAS users. This issue is more often observed in the domain of socio-ecological systems (SES), because SES domain experts are rarely programmers. Indeed, the majority of MAS platforms were not conceived taking into consideration domain-experts who are non-programmers. Most current MAS tools are not dedicated to SES, or nor do they possess an easily understandable formalism to represent the behaviors of agents. Moreover, because it is platform-dependent, a model realized in a given MAS platform cannot be properly used on another platform due to incompatibility between MAS platforms. To overcome these limitations, we propose a domain-specific language (DSL) to describe the behaviors of reactive agents, regardless of the MAS platform used for simulation. To achieve this result, we used model-driven engineering (MDE), an approach that provides tools to develop DSLs from a meta-model (abstract syntax), textual editors with syntax highlighting (for the concrete syntax) and code generation capabilities (for source-code generation of a model). As a result, we implemented a language and a textual editor that allow SES domain experts to describe behaviors in three different ways that are close to their natural expression: as equations when they are familiar with these, as a sequence of activities close to natural language or as an activity diagram to represent decisions and a sequence of behaviors using a graphic formalism. To demonstrate interoperability, we also developed code generators targeting two different MAS platforms (Cormas and Netlogo). We tested the code generators by implementing two SES models with the developed DSL. The generated code was targeted to both MAS platforms (Cormas and Netlogo), and successfully simulated in one of them. We conclude that the MDE approach provides adequate tools to develop DSL and code generators to facilitate MAS modeling and simulation by non-programmers. Concerning the DSL developed, although the behavioral aspect of MAS simulation is part of the complexity of modeling in MAS, there are still other essential aspects of model and simulation of MAS that are yet to be explored, such as model initialization and points of view on the model simulated worl

Transvaginal ultrasound versus magnetic resonance imaging for preoperative assessment of myometrial infiltration in patients with low-grade endometrioid endometrial cancer: A systematic review and head-to-head meta-analysis

Purpose: We aimed to compare the diagnostic performance of magnetic resonance imaging (MRI) and transvaginal ultrasound (TVS) for detecting myometrial invasion (MI) in patients with low-grade endometrioid endometrial carcinoma. Methods: A comprehensive search of MEDLINE (Pubmed), Web of Science, Embase and Scopus (from January 1990 to December 2022) was performed for articles comparing TVS and MRI in the evaluation of myometrial infiltration in low-grade (grade 1 or 2) endometrioid endometrial carcinoma in the same group of patients. We used QUADAS-2 tool for assessing the risk of bias of studies. Results: We found 104 citations in our extensive research. Four articles were ultimately included in the meta-analysis, after excluding 100 reports. All articles were considered low risk of bias in most of the domains assessed in QUADAS-2. We observed that pooled sensitivity and specificity for detecting deep MI were 65% (95% confidence interval [CI] = 54%-75%) and 85% (95% CI = 79%-89%) for MRI, and 71% (95% CI = 63%-78%) and 76% (95% CI = 67%-83%) for TVS, respectively. No statistical differences were found between both imaging techniques (p > 0.05). We observed low heterogeneity for sensitivity and high for specificity regarding TVS; and moderate for both sensitivity and specificity in case of MRI. Conclusions: The diagnostic performance of TVS and MRI for the evaluation of deep MI in women with low-grade endometrioid endometrial cancer is similar. However, further research is needed as the number of studies is scanty

Reducing the communication complexity with quantum entanglement

We propose a probabilistic two-party communication complexity scenario with a prior nonmaximally entangled state, which results in less communication than that is required with only classical random correlations. A simple all-optical implementation of this protocol is presented and demonstrates our conclusion.Comment: 4 Pages, 2 Figure

Molecular-orbital theory for the stopping power of atoms in the low velocity regime:the case of helium in alkali metals

A free-parameter linear-combination-of-atomic-orbitals approach is presented for analyzing the stopping power of slow ions moving in a metal. The method is applied to the case of He moving in alkali metals. Mean stopping powers for He present a good agreement with local-density-approximation calculations. Our results show important variations in the stopping power of channeled atoms with respect to their mean values.Comment: LATEX, 3 PostScript Figures attached. Total size 0.54