Ultrahigh dielectric constant of thin films obtained by electrostatic force microscopy and artificial neural networks

Copyright 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.A detailed analysis of the electrostatic interaction between an electrostatic force microscope tip and a thin film is presented. By using artificial neural networks, an equivalent semiinfinite sample has been described as an excellent approximation to characterize the whole thin film sample. A useful analytical expression has been also developed. In the case of very small thin film thicknesses (around 1 nm), the electric response of the material differs even for very high dielectric constants. This effect can be very important for thin materials where the finite size effect can be described by an ultrahigh thin filmdielectric constant.This work was supported by TIN2010-196079. G.M.S. acknowledges support from the Spanish Ramón y Cajal Program

Heterogeneous pair approximation for voter models on networks

For models whose evolution takes place on a network it is often necessary to augment the mean-field approach by considering explicitly the degree dependence of average quantities (heterogeneous mean-field). Here we introduce the degree dependence in the pair approximation (heterogeneous pair approximation) for analyzing voter models on uncorrelated networks. This approach gives an essentially exact description of the dynamics, correcting some inaccurate results of previous approaches. The heterogeneous pair approximation introduced here can be applied in full generality to many other processes on complex networks.Comment: 6 pages, 6 figures, published versio

Space-weighted seismic attenuation mapping of the aseismic source of Campi Flegrei 1983-84 unrest

Peer reviewedPublisher PD

Dawn of the Intercontinental Sniper: The Drone\u27s Cascading Contribution to the Modern Battlefield\u27s Complexity: A Re-View Essay of Predator: The Secret Origins of the Drone Revolution, by Richard Whittle

This review essay discusses a unique book that chronicles the UAV (unmanned aerial vehicle) or drone revolution with a focus on the Predator weapon system. Although brought to market by a mainstream publisher, the book offers a thought-provoking, heavily researched, non-fiction case study involving national security, defense acquisition, and international law. We congratulate author Richard Whittle for crafting a thrilling and highly informative history of technological innovation, government contracting, and weapons system development and deployment, while introducing complex issues of national security and international law, that nonetheless left us eagerly anticipating a forthcoming action movie. This review essay introduces prospective readers to a handful of the captivating characters that propel the Predator saga; identifies many interesting national security and international law issues raised in Whittle’s book; offers a disturbing anecdote about the extent to which the government’s post-millennial outsourcing has eroded the government’s monopoly over the use of force; paints a pessimistic picture of the Defense Acquisition System; and concludes that a broad range of sophisticated readers will enjoy the book. Ultimately, however, the book’s success makes the bottom line no less troubling. As much as Predator celebrates the initiative, creativity, ingenuity, commitment, and drive of exceptional people, it bemoans the stifling and inefficient acquisition regime that appears to value process over outcomes

Prizes! Innovating, Risk Shifting, and Avoiding Contracts and Grants

This short piece introduces prizes (or prize contests), which have become the darling of the Obama administration. Public managers increasingly find prizes more attractive than the more conventional and heavily regulated vehicles that they replace, contracts and grants. The paper explains some of the advantages of this increasingly popular approach and signals a cautionary note, particularly to contestants. Unfortunately, the government has not yet provided a straightforward means for contestants to obtain meaningful review if and when disputes arise. Accordingly, the authors suggest that, while shifting risk to the private sector is fair game, contest-sponsoring agencies should respect the private sector’s valuable intellectual capacity and scarce resources, and incorporate dispute resolution clauses into their competition guidelines. The authors anticipate publishing more extensive research on this topic in the near future

Simulación numérica de procesos atmosféricos. Parte I: Modelo de Nube

En este trabajo se presenta un modelo numérico de convección atmosférica tridimensional, que incluye los procesos de condensación de vapor y que tiene en cuenta la variación de los parámetros físicos con la altura. Las ecuaciones pronósticas que se presentan son resueltas por diferencias finitas en una grilla tipoPeer Reviewe

UV slope of z∼\sim3 bright (L>L∗L>L^{*}) Lyman-break galaxies in the COSMOS field

We analyse a unique sample of 517 bright ($L>L^{*}$) LBGs at redshift z$\sim$3 in order to characterise the distribution of their UV slopes $\beta$ and infer their dust extinction under standard assumptions. We exploited multi-band observations over 750 arcmin$^2$ of the COSMOS field that were acquired with three different ground-based facilities: the Large Binocular Camera (LBC) on the Large Binocular Telescope (LBT), the Suprime-Cam on the SUBARU telescope, and the VIRCAM on the VISTA telescope (ULTRAVISTA DR2). Our multi-band photometric catalogue is based on a new method that is designed to maximise the signal-to-noise ratio in the estimate of accurate galaxy colours from images with different point spread functions (PSF). We adopted an improved selection criterion based on deep Y-band data to isolate a sample of galaxies at $z\sim 3$ to minimise selection biases. We measured the UV slopes ($\beta$) of the objects in our sample and then recovered the intrinsic probability density function of $\beta$ values (PDF($\beta$)), taking into account the effect of observational uncertainties through detailed simulations. The galaxies in our sample are characterised by mildly red UV slopes with $\simeq -1.70$ throughout the enitre luminosity range that is probed by our data ($-24\lesssim M_{1600}\lesssim -21$). The resulting dust-corrected star formation rate density (SFRD) is $log(SFRD)\simeq-1.6 M_{\odot}/yr/Mpc^{3}$, corresponding to a contribution of about 25% to the total SFRD at z$\sim$3 under standard assumptions. Ultra-bright LBGs at $z \sim 3$ match the known trends, with UV slopes being redder at decreasing redshifts, and brighter galaxies being more highly dust extinct and more frequently star-forming than fainter galaxies. [abridged]Comment: Matched to journal version. 11 pages, 13 figures, Astronomy & Astrophysics in pres