Time-varying Huygens' meta-devices for parametric waves

Huygens' metasurfaces have demonstrated almost arbitrary control over the shape of a scattered beam, however, its spatial profile is typically fixed at fabrication time. Dynamic reconfiguration of this beam profile with tunable elements remains challenging, due to the need to maintain the Huygens' condition across the tuning range. In this work, we experimentally demonstrate that a time-varying metadevice which performs frequency conversion can steer transmitted or reflected beams in an almost arbitrary manner, with fully dynamic control. Our time-varying Huygens' metadevice is made of both electric and magnetic meta-atoms with independently controlled modulation, and the phase of this modulation is imprinted on the scattered parametric waves, controlling their shapes and directions. We develop a theory which shows how the scattering directionality, phase and conversion efficiency of sidebands can be manipulated almost arbitrarily. We demonstrate novel effects including all-angle beam steering and frequency-multiplexed functionalities at microwave frequencies around 4 GHz, using varactor diodes as tunable elements. We believe that the concept can be extended to other frequency bands, enabling metasurfaces with arbitrary phase pattern that can be dynamically tuned over the complete 2\pi range

Does The Manipulation of Tail Position Facilitate Extinction of Canine Phobic Behavior?

The phobic behavior of interest is tail tucking which is indicative of submission. In this study the tail was physically manipulated by the use of a custom made harness to hold the tail up in a dominant position to ideally extinguish phobic behavior through reciprocal inhibition. The harness did not hold the tail up the entire duration of the interventions, although it still held the base of the tail up. The intervention did not appear to have an affect on the two of the five subjects. The three more phobic canines did display some behavioral changes, although the changes noticed were not expected measures so they were not quantified. The changes observed are based on behavioral observation

Inelastic lifetimes of hot electrons in real metals

We report a first-principles description of inelastic lifetimes of excited electrons in real Cu and Al, which we compute, within the GW approximation of many-body theory, from the knowledge of the self-energy of the excited quasiparticle. Our full band-structure calculations indicate that actual lifetimes are the result of a delicate balance between localization, density of states, screening, and Fermi-surface topology. A major contribution from $d$-electrons participating in the screening of electron-electron interactions yields lifetimes of excited electrons in copper that are larger than those of electrons in a free-electron gas with the electron density equal to that of valence ($4s^1$) electrons. In aluminum, a simple metal with no $d$-bands, splitting of the band structure over the Fermi level results in electron lifetimes that are smaller than those of electrons in a free-electron gas.Comment: 4 papes, 2 figures, to appear in Phys. Rev. Let

Regional tax effort in Spain

This work examines in depth the hypotheses explaining the tax capacity of regional governments, also determining their tax effort and explanatory factors. The study is done for the Spanish regions, using different techniques which have rarely been applied in this area. The results show that these jurisdictions have exercised their tax autonomy responsibly, in response to different budget and demographic factors and to the economic cycle. Also, an asymmetrical tax behaviour linked to income is observed: some regions have practically exhausted the possibilities of current sub-central taxes, while others still have ample fiscal space

Regional tax effort in Spain

This work examines in depth the hypotheses explaining the tax capacity of regional governments, also determining their tax effort and explanatory factors. The study is done for the Spanish regions, using different techniques which have rarely been applied in this area. The results show that these jurisdictions have exercised their tax autonomy responsibly, in response to different budget and demographic factors and to the economic cycle. Also, an asymmetrical tax behaviour linked to income is observed: some regions have practically exhausted the possibilities of current sub-central taxes, while others still have ample fiscal space

Esquizofrenia: se a morte acontece sem aviso prévio, o que devemos propor para o futuro próximo?

Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaNational Institutes of Health National Institute of Mental HealthUNIFESP, EPMSciEL

El rol de las universidades y otras instituciones en el emprendimiento exitoso: visiones de una revisión de la literatura

The purpose of this paper is to analyze the role of universities and other institutions in successful entrepreneurship. Insights are obtained following a literature review approach. Case studies from the United States (New York startup), Spain (Mondragon), and Germany provide strong evidence that universities are very instrumental in the creation, design and implementation of entrepreneurial initiatives by providing new and ongoing entrepreneurs with human capital training, fundamentals, and theoretical and empirical models to contribute to lasting businesses. Results from university research on gender and risk-issues lead to believe that women are more risk averse than men to work and invest in star-up businesses. Other institutions, such as governments, are critical to provide with the necessary incentives to launch start-up businesses, including tax cuts, seed capital funding, investment in human capital, etc. While the evidence supporting the links between education and entrepreneurial outcomes is promisi g it is not yet definitive. In addition to providing a review of existing research, this paper suggests an integrative framework for future research.El objetivo de este artículo es analizar el rol de las universidades y otras instituciones en el emprendimiento exitoso. Se obtuvieron las diversas visiones sobre el tema a través de la revisión de la literatura. Estudios de casos de los Estados Unidos (emprendimientos Nueva York), España (Mondragón) y Alemania proveen pruebas claras de que las universidades son muy instrumentales en la creación, diseño e implementación de iniciativas empresariales al dar a los nuevos y actuales empresarios una formación en capital humano, fundamentos y modelos teóricos y empíricos para contribuir a los negocios que perduran en el tiempo. Los resultados de investigaciones sobre asuntos de género y riesgo muestran que las mujeres son menos propensas que los hombres a arriesgarse a trabajar e invertir en empresas nuevas. Otras instituciones, como los gobiernos, son decisivas en la facilitación de los incentivos necesarios para comenzar empresas nuevas, incluyendo recortes de impuestos, financiamiento de capital semilla, inversiones en capital humano, etc. Mientras la evidencia que apoya la relación entre la educación y los resultados empresariales es prometedora, aún no es definitiva. Además de ofrecer una revisión de investigaciones ya existentes, este artículo sugiere un marco teórico integrativo para investigaciones futuras