Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors

We report the fabrication and the characterization of carbon fibre tips for their use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors yielding a high quality factor and consequently a high force gradient sensitivity. This high force sensitivity in combination with high electrical conductivity and oxidation resistance of carbon fibre tips make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100 nm apex radius in a reproducible way which can yield high resolution images.Comment: 14 pages, 10 figure

Modelling the evolution of the Guadalquivir foreland basin (South Spain).

Previous quantitative studies dealing with the origin of foreland basins have focused primarily either on the rheological basis of the lithosphere mechanical response or on the relationship between orogenic loading and sediment geometry. To link the evolution of the Guadalquivir foreland basin (South Iberia) with the thermomechanical stratification of the Iberian lithosphere, we combine quantitative approaches to deep and shallow processes: thrust loading, lithospheric flexure, thickness changes of the crust and the lithospheric mantle, and surface mass transport. A planform flexural analysis of the present-day load distribution shows that basement subsidence is related not only to upper crustal thrusting but also to a deep-seated additional load. On the basis of the observed gravity and geoid fields, we propose this additional load to be related to a lithospheric mantle thickening larger than the coeval crustal thickening. Further modeling of the evolution of a basin cross section reveals that the architecture of the sedimentary basin is additionally related to the lithosphere rheological response. The quantitative study of the evolution of basement faulting and the forebulge uplift of Sierra Morena leads us to conclude that viscous stress relaxation and/or plastic yielding within the lithosphere are key processes to explain the flexural evolution of the basin

A very fast inference algorithm for finite-dimensional spin glasses: Belief Propagation on the dual lattice

Starting from a Cluster Variational Method, and inspired by the correctness of the paramagnetic Ansatz (at high temperatures in general, and at any temperature in the 2D Edwards-Anderson model) we propose a novel message passing algorithm --- the Dual algorithm --- to estimate the marginal probabilities of spin glasses on finite dimensional lattices. We show that in a wide range of temperatures our algorithm compares very well with Monte Carlo simulations, with the Double Loop algorithm and with exact calculation of the ground state of 2D systems with bimodal and Gaussian interactions. Moreover it is usually 100 times faster than other provably convergent methods, as the Double Loop algorithm.Comment: 23 pages, 12 figures. v2: improved introductio

Strongly quadrature-dependent noise in superconducting micro-resonators measured at the vacuum-noise limit

We measure frequency- and dissipation-quadrature noise in superconducting lithographed microwave resonators with sensitivity near the vacuum noise level using a Josephson parametric amplifier. At an excitation power of 100~nW, these resonators show significant frequency noise caused by two-level systems. No excess dissipation-quadrature noise (above the vacuum noise) is observed to our measurement sensitivity. These measurements demonstrate that the excess dissipation-quadrature noise is negligible compared to vacuum fluctuations, at typical readout powers used in micro-resonator applications. Our results have important implications for resonant readout of various devices such as detectors, qubits and nano-mechanical oscillators.Comment: 13 pages, 4 figure

Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Mechanical properties of freely suspended atomically thin dielectric layers of mica

We have studied the elastic deformation of freely suspended atomically thin sheets of muscovite mica, a widely used electrical insulator in its bulk form. Using an atomic force microscope, we carried out bending test experiments to determine the Young's modulus and the initial pre-tension of mica nanosheets with thicknesses ranging from 14 layers down to just one bilayer. We found that their Young's modulus is high (190 GPa), in agreement with the bulk value, which indicates that the exfoliation procedure employed to fabricate these nanolayers does not introduce a noticeable amount of defects. Additionally, ultrathin mica shows low pre-strain and can withstand reversible deformations up to tens of nanometers without breaking. The low pre-tension and high Young's modulus and breaking force found in these ultrathin mica layers demonstrates their prospective use as a complement for graphene in applications requiring flexible insulating materials or as reinforcement in nanocomposites.Comment: 9 pages, 5 figures, selected as cover of Nano Research, Volume 5, Number 8 (2012

Análisis sobre los avances de la Argentina en el cumplimiento de la meta 1.1 del objetivo “Fin de la pobreza” concertado en la Agenda 2030 de la Organización de las Naciones Unidas

El presente trabajo busca reflexionar respecto al progreso alcanzado en la obtención de uno de los Objetivos de Desarrollo Sostenible (ODS) que fuera acordado en la “Agenda 2030”, en particular para Argentina. Para ello, se ha trabajado sobre el área de personas y en el objetivo 1: “Fin de la pobreza”, considerando que este es el problema más dramático que enfrenta la humanidad en su conjunto. Teniendo en cuenta que la temática establecida resulta de una significativa amplitud, hemos decidido enfocarnos en el análisis de los avances conquistados a partir de las políticas implementadas en este país para poder arribar a la meta 1.1 dentro del ODS número 1 de la Agenda. Con ese propósito se realizó un pormenorizado análisis de diferentes indicadores, con la intención de establecer la evolución que ha tenido la pobreza en los últimos años. Una vez obtenidos los distintos índices, se expresaron conclusiones relacionadas y una posible solución como propuesta de mejora a la situación que ha sido establecida al respecto