Una familia de elementos finitos clase C1, aplicación a flexión de placas de Kirchhoff

Se hace una pequeña introducción y después un estudio sobre las posibilidades y limitaciones en análisis de placas delgadas de elementos simples polinómicos de clase C1. Se expone una familia jerárquica de dichos elementos, que se aplica a varios casos particulares. En base a estos se deducen algunas conclusiones, especialmente en lo que se refiere a eficacia computacional. Al final se proponen trabajos a realizar a partir de los datos existentesPeer Reviewe

Analytic results for NN particles with 1/r21/r^2 interaction in two dimensions and an external magnetic field

The $2N$-dimensional quantum problem of $N$ particles (e.g. electrons) with interaction $\beta/r^2$ in a two-dimensional parabolic potential $\omega_0$ (e.g. quantum dot) and magnetic field $B$, reduces exactly to solving a $(2N-4)$-dimensional problem which is independent of $B$ and $\omega_0$. An exact, infinite set of relative mode excitations are obtained for any $N$. The $N=3$ problem reduces to that of a ficticious particle in a two-dimensional, non-linear potential of strength $\beta$, subject to a ficticious magnetic field $B_{\rm fic}\propto J$, the relative angular momentum.Comment: To appear in Physical Review Letters (in press). RevTeX file. Two figures available from [email protected] or [email protected]

Ultrafast non-linear optical signal from a single quantum dot: exciton and biexciton effects

We present results on both the intensity and phase-dynamics of the transient non-linear optical response of a single quantum dot (SQD). The time evolution of the Four Wave Mixing (FWM) signal on a subpicosecond time scale is dominated by biexciton effects. In particular, for the cross-polarized excitation case a biexciton bound state is found. In this latter case, mean-field results are shown to give a poor description of the non-linear optical signal at small times. By properly treating exciton-exciton effects in a SQD, coherent oscillations in the FWM signal are clearly demonstrated. These oscillations, with a period corresponding to the inverse of the biexciton binding energy, are correlated with the phase dynamics of the system's polarization giving clear signatures of non-Markovian effects in the ultrafast regime.Comment: 10 pages, 3 figure

Fog function virtualization: A flexible solution for IoT applications

The Internet of Things applications must carefully assess certain crucial factors such as the real-time and largely distributed nature of the “things”. Fog Computing provides an architecture to satisfy those requirements through nodes located from near the “things” till the edge. The problem comes with the integration of the Fog nodes into current infrastructures. This process requires the development of complex software solutions and prevents Fog growth. In this paper we propose three innovations to enhance Fog: (i) a new orchestration policy, (ii) the creation of constellations of nodes, and (iii) Fog Function Virtualization (FFV). All together will complement Fog to reach its true potential as a generic scalable platform, running multiple IoT applications simultaneously. Deploying a new service is reduced to the development of the application code, fact that brings the democratization of the Fog Computing paradigm through ease of deployment and cost reduction.The authors thanks Rodolfo Milito for his insightful comments and revisions. Damian Roca work was supported by a Doctoral Scholarship provided by Fundación La Caixa. Josue V. Quiroga work was supported by a Doctoral Scholarship provided by the Mexican National Council of Science and Technology (CONACyT). This work has been supported by the Spanish Government (Severo Ochoa grants SEV2015-0493) and by the Spanish Ministry of Science and Innovation (contracts TIN2015-65316-P).Peer ReviewedPostprint (author's final draft

Diversity, abundance, and distribution of ground invertebrates in Lower Sharpham Farm

Invertebrates constitute the largest group of animals on Earth and represent the bulk of biodiversity. They are responsible for numerous essential ecosystems services and are at the centre of many terrestrial food webs. Due to habitat loss from land use change and conversion to intensive agriculture, they are experiencing a substantial decline in biodiversity, hence conservation approaches such as rewilding have been sought. There are limited studies of invertebrate biodiversity in rewilding projects, therefore the aim of this study is to investigate the diversity and abundance of ground invertebrates at Lower Sharpham Farm and the influences of vegetation structure in a rewilded field and a farmed field. 18 pitfall traps were installed in each field divided into 3 groups of 6 and were left outside for 5 days. After collection, 856 invertebrates were found and identified in the laboratory. During that period, a vegetation survey was also carried out. Results within rewilded field indicate that group 1 showed to have a higher invertebrate abundance (n=205) and species richness (n=15) with higher biodiversity index (H=1.88). Results within farmed field indicate that the area in group 1 showed to have a higher invertebrate abundance (n=124) while group 3 had a higher species richness (n=13) with a higher biodiversity index result (H=2.12). Results between fields comparison indicate that rewilded fields increase invertebrate abundance (n=559), though grazing in farmed fields has little effect on invertebrate richness but decreases abundance (n=297). Farmed field had a slightly higher biodiversity index result (H=1.87) compared to rewilded field (H=1.82) due to the high dominance of springtails (Entomobryomorpha). This study determines that rewilding works as a tool for promoting invertebrate abundance and that organic farms have a positive impact on invertebrate diversity. Overall, long-term regular monitoring is needed to evaluate the success of rewilding for biodiversity overtime. The outcomes of the study not only evidence the importance of rewilding for invertebrate conservation but also the importance of low intensive agriculture practices for biodiversity

Dynamics of quantum correlations and linear entropy in a multi-qubit-cavity system

We present a theoretical study of the relationship between entanglement and entropy in multi-qubit quantum optical systems. Specifically we investigate quantitative relations between the concurrence and linear entropy for a two-qubit mixed system, implemented as two two-level atoms interacting with a single-mode cavity field. The dynamical evolutions of the entanglement and entropy, are controlled via time-dependent cavity-atom couplings. Our theoretical findings lead us to propose an alternative measure of entanglement, which could be used to develop a much needed correlation measure for more general multi-partite quantum systems.Comment: New discussions on the generality of entanglement-entropy relationship, one new reference, and other minor changes. 10 pages, 6 figures, accepted for publication in J.Opt. B: "Special Issue on Fluctuations & Noise in Photonics & Quantum Optics.

Entangled microwaves as a resource for entangling spatially separate solid-state qubits: Superconducting qubits, nitrogen-vacancy centers, and magnetic molecules

13 págs.; 10 figs.; 2 apps.Quantum correlations present in a broadband two-line squeezed microwave state can induce entanglement in a spatially separated bipartite system consisting of either two single qubits or two-qubit ensembles. By using an appropriate master equation for a bipartite quantum system in contact with two separate but entangled baths, the generating entanglement process in spatially separated quantum systems is thoroughly characterized. Decoherence thermal effects on the entanglement transfer are also discussed. Our results provide evidence that this entanglement transfer by dissipation is feasible, yielding to a steady-state amount of entanglement in the bipartite quantum system which can be optimized for a wide range of realistic physical systems that include state-of-the-art experiments with nitrogen-vacancy centers in diamond, superconducting qubits, or even magnetic molecules embedded in a crystalline matrix. ©2016 American Physical SocietyA.V.G., F.J.R., and L.Q. acknowledge financial support from Facultad de Ciencias at UniAndes-2015 Project “Transfer of Correlations from Non-classically Correlated Reservoirs to Solid State Systems” and Project “Quantum Control of Non-equilibrium Hybrid Systems-Part II,” UniAndes-2015. J.J.G.R. acknowledges support from Spanish Mineco Project No. FIS2012-33022, from EU FP7 Project PROMISCE, from CAM Research Network QUITEMAD+.Peer Reviewe

Partially incoherent optical vortices in self-focusing nonlinear media

We observe stable propagation of spatially localized single- and double-charge optical vortices in a self-focusing nonlinear medium. The vortices are created by self-trapping of partially incoherent light carrying a phase dislocation, and they are stabilized when the spatial incoherence of light exceeds a certain threshold. We confirm the vortex stabilization effect by numerical simulations and also show that the similar mechanism of stabilization applies to higher-order vortices.Comment: 4 pages and 6 figures (including 3 experimental figures

Long-term impact of chemical and alternative fungicides applied to grapevine CV nebbiolo on berry transcriptome

Viticulture is one of the horticultural systems in which antifungal treatments can be extremely frequent, with substantial economic and environmental costs. New products, such as biofungicides, resistance inducers and biostimulants, may represent alternative crop protection strategies respectful of the environmental sustainability and food safety. Here, the main purpose was to evaluate the systemic molecular modifications induced by biocontrol products as laminarin, resistance inducers (i.e., fosetyl-Al and potassium phosphonate), electrolyzed water and a standard chemical fungicide (i.e., metiram), on the transcriptomic profile of ‘Nebbiolo’ grape berries at harvest. In addition to a validation of the sequencing data through real-time polymerase chain reaction (PCR), for the first-time the expression of some candidate genes in different cell-types of berry skin (i.e., epidermal and hypodermal layers) was evaluated using the laser microdissection approach. Results showed that several considered antifungal treatments do not strongly affect the berry transcriptome profile at the end of season. Although some treatments do not activate long lasting molecular defense priming features in berry, some compounds appear to be more active in long-term responses. In addition, genes differentially expressed in the two-cell type populations forming the berry skin were found, suggesting a different function for the two-cell type populations