Comment on ‘On the dipole, velocity and acceleration forms in high-order harmonic generation from a single atom or molecule’

Authors acknowledge support from Spanish Ministerio de Ciencia e Innovacio ́n through the Consolider Program SAUUL (CSD2007-00013) and research project FIS2009-09522, from Junta de Castilla y Leo ́n through the Program for Groups of Excellence (GR27) and from the EC’s Seventh Framework Programme (LASERLAB-EUROPE, grant agreement no 228334)We show that the main conclusion of Baggesen and Madsen (2011 J. Phys. B: At. Mol. Opt. Phys. 44 115601) is not general but only valid in one dimension

Critical analysis of the European Union directive which regulates the use of biofuels: An approach to the Spanish case

In recent times, the global debate on the environment has been centered on CO2 emissions. This gas is the major cause of the “greenhouse effect” and people are more concerned with the idea that the emissions of this gas should be minimized. As a result of this concern, the Kyoto Protocol was enacted and subscribed to by many countries, setting the maximum gas emissions for them. Fossil fuels are a major source of CO2 emissions. For some years now The European Union has been seeking to promote some years now the use of biofuels as substitutes for diesel or petrol for transport purposes. As a result of this policy, in 2003 the European Union (EU) Directive 2003/30/EC [1] was developed with the aim of promoting the use of biofuels as a substitute for diesel or gasoline among European Union countries as well as to contribute to fulfilling the commitments acquired on climate change, security of supply in environmentally friendly conditions and the promotion of renewable energy sources. In order to achieve these goals, the directive forces all EU members to ensure that before December 31 of 2010 at least 5.75% of all gasoline and diesel fuels sold for transport purposes are biofuels. European Union countries have social and economic characteristics unique to themselves. The energy dependence on foreign sources, the features of the agricultural sector or the degree of industrialization varies greatly from one country to another. In this context, it is questionable whether the obligation imposed by this directive is actually achieving in its application uniform and/or identical goals in each of the countries involved and whether the actions of the various governments are also aligned with these goals. All these ideas were developed in a previous report (Sobrino and Monroy (2009) [2]). This report examines the possibility of using hydrogen as an alternative to fossil fuels and biofuels from a technical, economic and environmental point of view in the specific case of a European Union country: Spain

Valley in the efficiency of the high-order harmonic yield at ultra-high laser intensities

We study the process of high-order harmonic generation using laser pulses with non-adiabatic turn-on and intensities well above saturation. As a main point, we report the existence of a valley structure in the efficiency of single-atom high-order harmonic generation with increasing laser intensities. Consequently, after an initial decrease, the high-frequency radiation yield is shown to increase for higher intensities, returning to a level similar to the case below saturation. Such behavior contradicts the general belief of a progressive degradation of the harmonic emission at ultrahigh intensities, based on the experience with pulses with smoother turn-on. We shall show that this behavior corresponds to the emergence of a new pathway for high-order harmonic generation, which takes place during the pulse turn-on. Our study combines trajectory analysis, wavelet techniques and the numerical integration of 3-Dimensional Time Dependent Schrödinger Equation. The increase in efficiency raises the possibility of employing ultrahigh intensities to generate high-frequency radiation beyond the water window.Spanish Ministerio de Ciencia e Innovación through the Consolider Program SAUUL ( CSD2007-00013) and research project FIS2009-09522, from Junta de Castilla y León through the Program for Groups of Excellence (GR27) and from the EC’s Seventh Framework Programme ( LASERLAB-EUROPE, grant agreement n 228334)

Alu retrotransposons promote differentiation of human carcinoma cells through the aryl hydrocarbon receptor

Cell differentiation is a central process in development and in cancer growth and dissemination. OCT4 (POU5F1) and NANOG are essential for cell stemness and pluripotency; yet, the mechanisms that regulate their expression remain largely unknown. Repetitive elements account for almost half of the Human Genome; still, their role in gene regulation is poorly understood. Here, we show that the dioxin receptor (AHR) leads to differentiation of human carcinoma cells through the transcriptional upregulation of Alu retrotransposons, whose RNA transcripts can repress pluripotency genes. Despite the genome-wide presence of Alu elements, we provide evidences that those located at the NANOG and OCT4 promoters bind AHR, are transcribed by RNA polymerase-III and repress NANOG and OCT4 in differentiated cells. OCT4 and NANOG repression likely involves processing of Alu-derived transcripts through the miRNA machinery involving the Microprocessor and RISC. Consistently, stable AHR knockdown led to basal undifferentiation, impaired Alus transcription and blockade of OCT4 and NANOG repression. We suggest that transcripts produced from AHR-regulated Alu retrotransposons may control the expression of stemness genes OCT4 and NANOG during differentiation of carcinoma cells. The control of discrete Alu elements by specific transcription factors may have a dynamic role in genome regulation under physiological and diseased conditions.Ministerio de Economía y Competitividad [BFU2011- 22678, SAF2014-51813-R to P.M.F-S.]; Junta de Extremadura [GR10008, GR15008]; Red Temática de Investigación Cooperativa en Cáncer (RTICC); Carlos III Institute; Spanish Ministry of Economy and Competitiveness [RD12/0036/0032]; FPI Fellowship from the Junta de Extremadura (to A.M.H.); Marie Curie IRG project (FP7-PEOPLE-2007-4-3-IRG: SOMATIC LINE-1, in part to A.M.); CICE-FEDER-P09-CTS-4980, CICE-FEDERP12- CTS-2256, Plan Nacional de I+D+I 2008–2011 and 2013–2016 (FIS-FEDER-PI11/01489, FIS-FEDERPI14/ 02152), PCIN-2014-115-ERA-NET NEURON II (to J.L.G.P.); European Research Council [ERC-Consolidator ERC-STG-2012-233764]; International Early Career Scientist grant from the Howard Hughes Medical Institute [IECS-55007420]; European Union FEDER program. Funding for open access charge: Ministerio de Economía y Competitividad [BFU2011-22678, SAF2014-51813-R to P.M.F-S.]

High-order harmonic propagation in gases within the discrete dipole approximation.

[EN]We present an efficient approach for computing high-order harmonic propagation based on the discrete dipole approximation. In contrast with other approaches, our strategy is based on computing the total field as the superposition of the driving field with the field radiated by the elemental emitters of the sample. In this way we avoid the numerical integration of the wave equation, as Maxwell’s equations have an analytical solution for an elementary (pointlike) emitter. The present strategy is valid for low-pressure gases interacting with strong fields near the saturation threshold (i.e., partially ionized), which is a common situation in the experiments of high-order harmonic generation. We use this tool to study the dependence of phase matching of high-order harmonics with the relative position between the beam focus and the gas jet

Analytical and experimental performance evaluation of BLE neighbor discovery process including non-idealities of real chipsets

The purpose of this paper is to evaluate from a real perspective the performance of Bluetooth Low Energy (BLE) as a technology that enables fast and reliable discovery of a large number of users/devices in a short period of time. The BLE standard specifies a wide range of configurable parameter values that determine the discovery process and need to be set according to the particular application requirements. Many previous works have been addressed to investigate the discovery process through analytical and simulation models, according to the ideal specification of the standard. However, measurements show that additional scanning gaps appear in the scanning process, which reduce the discovery capabilities. These gaps have been identified in all of the analyzed devices and respond to both regular patterns and variable events associated with the decoding process. We have demonstrated that these non-idealities, which are not taken into account in other studies, have a severe impact on the discovery process performance. Extensive performance evaluation for a varying number of devices and feasible parameter combinations has been done by comparing simulations and experimental measurements. This work also includes a simple mathematical model that closely matches both the standard implementation and the different chipset peculiarities for any possible parameter value specified in the standard and for any number of simultaneous advertising devices under scanner coverage

Weighted LpL^p-boundedness of Fourier series with respect to generalized Jacobi weights

Let w be a generalized Jacobi weight on the interval [-1,1] and, for each function f, let Snf denote the n-th partial sum of the Fourier series of f in the orthogonal polynomials associated to w. We prove a result about uniform boundedness of the operators Sn in some weighted Lp spaces. The study of the norms of the kernels Kn related to the operators Sn allows us to obtain a relation between the Fourier series with respect to different generalized Jacobi weights

Developments in Spanish public debt since the start of the crisis

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Evaluación de algunos aspectos de la biocompatibilidad de biomateriales in vitro

Los biomateriales para uso médico se han ido desarrollando de acuerdo a los avances en los campos de la medicina, bioquímica, farmacia y las ciencias de los materiales. Estos deben ser biocompatibles, por eso es necesario desarrollar un grupo de ensayos biológicos encaminados a este fin. Las pruebas de citotoxicidad in vitro tienen aplicabilidad general y uso extensamente difundido en la evaluación de un amplio rango de materiales. Se ha encontrado cierta relación entre la citotoxicidad no específica del biomaterial in vitro y su efecto irritante in vivo. En nuestro laboratorio se aplicó el método descrito por Stanley HR (1985) para la evaluación toxicológica de biomateriales, habiéndose evaluado hasta la fecha diferentes materiales obtenidos en el Centro de Biomateriales de la Universidad de La Habana, entre ellos: el obturante dental Obtudent Fotocurado (FC), el sellante dental Cubridem Autocurado (AC), el adhesivo tisular Tisuacryl y los cementos óseos Biograft-G y Apafill-G. El Obtudent FC resultó citotóxico, sin embargo su citotoxicidad se encontró en el rango de la de sus análogos comerciales. La citotoxicidad del Cubridem AC y del Tisuacryl no se diferenció significativamente de los niveles encontrados para sus controles comerciales, al igual que el Biograft-G, aunque en este caso el resultado fue ligeramente citotóxico según la clasificación de Stanley. El Apafill-G no resultó citotóxico.Peer Reviewe