Interactions between directly and parametrically driven vibration modes in a micromechanical resonator

The interactions between parametrically and directly driven vibration modes of a clamped-clamped beam resonator are studied. An integrated piezoelectric transducer is used for direct and parametric excitation. First, the parametric amplification and oscillation of a single mode are analyzed by the power and phase dependence below and above the threshold for parametric oscillation. Then, the motion of a parametrically driven mode is detected by the induced change in resonance frequency in another mode of the same resonator. The resonance frequency shift is the result of the nonlinear coupling between the modes by the displacement-induced tension in the beam. These nonlinear modal interactions result in the quadratic relation between the resonance frequency of one mode and the amplitude of another mode. The amplitude of a parametrically oscillating mode depends on the square root of the pump frequency. Combining these dependencies yields a linear relation between the resonance frequency of the directly driven mode and the frequency of the parametrically oscillating mode.Comment: 5 pages, 4 figure

Should We Use a Total Score, Two Subscale Scores, or Six Subscale Scores for the Self-Compassion Scale? A Multi-faceted Assessment Beyond Model Fit Indices

Datos alojados en : https://osf.io/a98n7/[EN] Objectives The aim of this study was to conduct a multi-faceted assessment of the psychometric properties of the Self Compassion Scale (SCS). In addition to the goodness-of-ft, we aimed to assess the strength and replicability of three factorial solutions, and the quality and efectiveness of the three scoring schemes of the scale (i.e., total scale score, two subscale scores, and six subscale scores). Methods Participants were 1508 Spanish-speaking community-dwelling adults (M =34.94 years, SD=15.02). Data were examined by means of a conjoint strategy using Rasch modeling, non-linear factor analysis, exploratory bifactor analysis, and parallel analysis. A procedure for selecting the optimal set of items that must be used to compute individual’s scores was used.Results The unidimensional solution showed a marginal model ft (RMSR=.089), and both the bifactor two-group and bifactor six-group solutions showed a good ft (RMSR=.043 and .019, respectively). However, only the unidimensional and the bifactor two-factor solutions showed interpretable and replicable factor structures, and high-quality and efective scores to be used for measurement purposes. Subscale scores derived from the six primary factors did not show adequate psychometric properties. It was observed that the information provided by 10 items was redundant and had already been provided by the other 16 items. Conclusions Good model ft is neither sufcient nor necessary to justify the use of a scoring scheme. Goodness-of-ft statistics should be complemented by anassessment of the metric properties of the resulting scores when proposing SCS scoring schemes.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Exploring the transferability of large supramolecular assemblies to the vacuum-solid interface

We present an interplay of high-resolution scanning tunneling microscopy imaging and the corresponding theoretical calculations based on elastic scattering quantum chemistry techniques of the adsorption of a gold-functionalized rosette assembly and its building blocks on a Au(111) surface with the goal of exploring how to fabricate functional 3-D molecular nanostructures on surfaces. The supramolecular rosette assembly stabilized by multiple hydrogen bonds has been sublimed onto the Au(111) surface under ultra-high vacuum conditions; the resulting surface nanostructures are distinctly different from those formed by the individual molecular building blocks of the rosette assembly, suggesting that the assembly itself can be transferred intact to the surface by in situ thermal sublimation. This unanticipated result will open up new perspectives for growth of complex 3-D supramolecular nanostructures at the vacuum-solid interface

Factors modulating herbivory patterns in Cymodocea nodosa meadows

In coastal marine food webs, seagrass-grazer interactions play a fundamental role in ecological processes by regulating the structure and functioning of plant communities. Therefore, assessing the strength of these seagrass-grazer links and identifying the mechanisms that regulate these relationships are crucial to increasing our understanding of community and ecosystem structure and dynamics. Herbivory on the temperate seagrass Cymodocea nodosa was evaluated in four locations with contrasting abiotic and biotic factors (i.e., depth; meadow size; seagrass shoot density, productivity, and leaf traits; and herbivore presence) using cross-transplantation experiments carried out once per season to account for seasonal variation. Patterns of feeding rates on C. nodosa meadows showed high temporal variability, with peaks occurring in spring and summer. Results indicate that between 46.59% and 74.08% of the annual leaf production is lost to herbivory at the locations sampled in this study. Herbivory rates increased with higher nitrogen content and shoot density for all types of consumers (mesograzers, fishes, and sea urchins). This work highlights the need to integrate the abiotic and biotic factors modulating herbivory patterns, particularly in a foundation species like C. nodosa, for which changes in plant traits and grazer abundance may trigger trophic cascades with far-reaching consequences for associated species.This study was funded by the Spanish national project CTM2011-24482 (SEA-LIVE), by the Junta de Andalucia Excelence Project PRODESCA (P12-RNM-3020)) and by Ser-Cady project (FEDER-UCA18-107451) cofinanced by the 2014–2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia. We thank Carmen Henares for field assistance

The Poopó polymetallic epithermal deposit, Bolivia: mineralogy, genetic constraints, and distribution of critical elements

The tin-rich polymetallic epithermal deposit of Poopó, of plausible Late Miocene age, is part of the Bolivian Tin Belt. As an epithermal low sulfidation mineralisation, it represents a typological end-member within the “family” of Bolivian tin deposits. The emplacement of the mineralisation was controlled by the regional fault zone that constitutes the geological border between the Bolivian Altiplano and the Eastern Andes Cordillera. In addition to Sn and Ag, its economic interest resides in its potential in critical elements as In, Ga and Ge. This paper provides the first systematic characterisation of the complex mineralogy and mineral chemistry of the Poopó deposit with the twofold aim of identifying the mineral carriers of critical elements and endeavouring to ascertain plausible metallogenic processes for the formation of this deposit, by means of a multi-methodological approach. The poor development of hydrothermal alteration assemblage, the abundance of sulphosalts and the replacement of löllingite and pyrrhotite by arsenopyrite and pyrite, respectively, indicate that this deposit is ascribed to the low-sulphidation subtype of epithermal deposits, with excursions into higher states of sulphidation. Additionally, the occurrence of pyrophyllite and topaz has been interpreted as the result of discrete pulses of high-sulphidation magmatic fluids. The d34SVCDT range in sulphides (-5.9 to -2.8‰) is compatible either with: (i) hybrid sulphur sources (i.e., magmatic and sedimentary or metasedimentary); or (ii) a sole magmatic source involving magmas that derived from partial melting of sedimentary rocks or underwent crustal assimilation. In their overall contents in critical elements (In, Ga and Ge), the key minerals in the Poopó deposit, based on their abundance in the deposit and compositions, are rhodostannite, franckeite, cassiterite, stannite and, less importantly, teallite, sphalerite and jamesonite.Peer ReviewedPostprint (published version

Aprendizaje activo en prácticas de laboratorio basadas en difracción de la luz

Memoria ID-037. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2019-2020

Indium mineralization in the volcanic dome-hosted Ánimas–Chocaya–Siete Suyos polymetallic deposit, Potosí, Bolivia

A volcanic dome complex of Miocene age hosts the In-bearing Ánimas–Chocaya–Siete Suyos district in SW Bolivia. Ore mineralization occurs as banded and massive infillings in subvertical, NE-SW striking veins. In this article, a detailed petrographic study is combined with in situ mineral geochemistry determinations in ore from the Arturo, Chorro and Diez veins in the Siete Suyos mine, the Ánimas, Burton, Colorada, and Rosario veins in the Ánimas mine and the Nueva vein in the Chocaya mine. A three-stage paragenetic sequence is roughly determined for all of them, and includes (1) an early low-sulfidation stage that is dominated by cassiterite, pyrrhotite, arsenopyrite, and high-Fe sphalerite (FeS > 21 mol. %); (2) a second intermediate-sulfidation stage dominated by pyrite + marcasite ± intermediate product, sphalerite (FeS < 21 mol. %), stannite, and local famatinite; and, (3) a late intermediate-sulfidation stage dominated by galena and Ag-Pb-Sn sulfosalts. Electron-probe microanalyses reveal high indium enrichment in stage-2 sphalerite (up to 9.66 wt.% In) and stannite (up to 4.11 wt.% In), and a moderate enrichment in rare wurtzite (up to 1.61 wt.% In), stage-1 sphalerite (0.35 wt.% In), cassiterite (up to 0.25 wt.% In2O3), and ramdohrite (up to 0.24 wt.% In). Therefore, the main indium mineralization in the district can be associated to the second, intermediate-sulfidation stage, chiefly in those veins in which sphalerite and stannite are more abundant. Atomic concentrations of In and Cu in sphalerite yield a positive correlation at Cu/In = 1 that agrees with a (Cu+ + In3+) ¿ 2Zn2+ coupled substitution. The availability of Cu in the mineralizing fluids during the crystallization of sphalerite is, in consequence, essential for the incorporation of indium in its crystal lattice and would control the distribution of indium enrichment at different scales. The highest concentrations of indium in sphalerite, which is found in the Diez vein in the Siete Suyos mine, occur in crustiform bands of sphalerite with local “chalcopyrite disease” texture, which has not been observed in the other studied veins. In stannite, the atomic concentrations of In are negatively correlated with those of Cu and Sn at Cu + In = 2 and Sn + In = 1. Thus, atomic proportions and correlations suggest the contextualization of the main indium mineralization in the sphalerite–stannite–roquesite pseudoternary system.Peer ReviewedPostprint (published version

Ngram-based statistical machine translation enhanced with multiple weighted reordering hypotheses

This paper describes the 2007 Ngram-based sta-tistical machine translation system developed at the TALP Research Center of the UPC (Uni-versitat Politecnica de Catalunya) in Barcelona. Emphasis is put on improvements and extensions of the previous years system, being highlighted and empirically compared. Mainly, these include a novel word ordering strategy based on: (1) sta-tistically monotonizing the training source cor-pus and (2) a novel reordering approach based on weighted reordering graphs. In addition, this system introduces a target language model based on statistical classes, a feature for out-of-domain units and an improved optimization procedure. The paper provides details of this system par-ticipation in the ACL 2007 SECOND WORK-SHOP ON STATISTICAL MACHINE TRANSLA-TION. Results on three pairs of languages are reported, namely from Spanish, French and Ger-man into English (and the other way round) for both the in-domain and out-of-domain tasks.