Filtenna Integration Achieving Ideal Chebyshev Return Losses

This paper demonstrates that it is possible to find an ideal filter response (Chebyshew, Butterworth,..) considering the antenna as the last resonator of a filter under certain circumstances related with the antenna performance and the bandwidth of the filtenna device. If these circumstances are not accomplished, we can achieve excellent performance as well, by means of an iterative process the goal of which is defined by either a filter mask or a classical filter function itself. The methodology is based on the conventional coupling matrix technique for filter design and has been validated by fabricating a microstrip prototype using hairpin resonators and a rectangular patch antenna

The Ellipse Law: Kirchhoff Meets Dislocations

In this paper we consider a nonlocal energy I \u3b1 whose kernel is obtained by adding to the Coulomb potential an anisotropic term weighted by a parameter \u3b1 08 R. The case \u3b1 = 0 corresponds to purely logarithmic interactions, minimised by the circle law; \u3b1 = 1 corresponds to the energy of interacting dislocations, minimised by the semi-circle law. We show that for \u3b1 08 (0 , 1) the minimiser is the normalised characteristic function of the domain enclosed by the ellipse of semi-axes 1-\u3b1 and 1+\u3b1. This result is one of the very few examples where the minimiser of a nonlocal anisotropic energy is explicitly computed. For the proof we borrow techniques from fluid dynamics, in particular those related to Kirchhoff\u2019s celebrated result that domains enclosed by ellipses are rotating vortex patches, called Kirchhoff ellipses

Top Quark Mass Calibration for Monte Carlo Event Generators -- An Update

We generalize and update our former top quark mass calibration framework for Monte Carlo (MC) event generators based on the $e^+e^-$ hadron-level 2-jettiness $\tau_2$ distribution in the resonance region for boosted $t\bar t$ production, that was used to relate the PYTHIA 8.205 top mass parameter $m_t^{\rm MC}$ to the MSR mass $m_t^{\rm MSR}(R)$ and the pole mass $m_t^{\rm pole}$. The current most precise direct top mass measurements specifically determine $m_t^{\rm MC}$. The updated framework includes the addition of the shape variables sum of jet masses $\tau_s$ and modified jet mass $\tau_m$, and the treatment of two more gap subtraction schemes to remove the ${\cal O}(\Lambda_{\rm QCD})$ renormalon related to large-angle soft radiation. These generalizations entail implementing a more versatile shape-function fit procedure and accounting for a certain type of $(m_t/Q)^2$ power corrections to achieve gap-scheme and observable independent results. The theoretical description employs boosted heavy-quark effective theory (bHQET) at next-to-next-to-logarithmic order (N$^2$LL), matched to soft-collinear effective theory (SCET) at N$^2$LL and full QCD at next-to-leading order (NLO), and includes the dominant top width effects. Furthermore, the software framework has been modernized to use standard file and event record formats. We update the top mass calibration results by applying the new framework to PYTHIA 8.205, HERWIG 7.2 and SHERPA 2.2.11. Even though the hadron-level resonance positions produced by the three generators differ significantly for the same top mass parameter $m_t^{\rm MC}$ value, the calibration shows that these differences arise from the hadronization modeling. Indeed, we find that $m_t^{\rm MC}$ agrees with m_t^{\rm MSR}(1\,\mbox{GeV}) within $200$ MeV for the three generators and differs from the pole mass by $350$ to $600$ MeV.Comment: 70 pages, 15 figure

Searching for RR Lyrae stars in the Canis Major Overdensity

The Canis Major overdensity (CMa) was initially proposed to be the remnant of a tidally disrupting dSph galaxy. Since its nature is still subject of debate, the goal of the present work was to conduct a large-scale RR Lyrae survey in CMa, in order to see if there is an overdensity of these stars. The survey spans a total area of ~34 sq. deg. with observations in V and R filters, made with the 1.0m Jurgen Stock Schmidt telescope at the National Astronomical Observatory of Venezuela. Current results in a subregion, including spectroscopic observations, show that the small number of RR Lyrae stars found can be accounted for by the halo and thick disk components of our Galaxy.Comment: 2 pages, 1 figure, to appear in the proceedings of IAU Symposium No241 "Stellar Populations as Building Blocks of Galaxies

Datos imprecisos y mapas de distribución: el ejemplo de Phylan semicostatus Mulsant y Rey, 1854 (Coleoptera, Tenebrionidae) en la Serra de Tramuntana (Mallorca, Mediterráneo occidental)

Distribution maps are key tools for environmental management and biogeographic analyses. However, success in predicting spatial distribution is limited when using noisy presence/absence data sets. Both false absences and presences can be related with local departures from equilibrium (for example, temporary extinctions or unsuccessful colonisations). Moreover, false absences can arise from limited sampling effort. Here we explore an analytical strategy to get additional information on the presence/absence pattern of one target species from the presence/absence of all other species in the community. The logic is simple: the target species should display higher probability of presence at a site if a sample from this site is faunistically very close to the samples from other sites where the species occurs. Therefore, we first model presence/absence of the target species as a function of between-sample faunistic similarity. Second, the observed data for the target species are readjusted as a function of the expected probability of presence: current presences at sites with extreme low probability of presence are interpreted as unstable presences, and are recoded as absences. Seemingly, absences at sites with high probability of presence are interpreted as false absences, and are recoded as presences. In the experimental case presented herein, the recoding procedure is based on the presence/absence of 174 species, covering a broad taxonomic scope (snails, beetles, spiders and isopods). 1 km2 distribution maps of presence/absence of the endemic beetle Phylan semicostatus were modelled from these recoded data. Mapping is done using GARP based on four environmental explanatory variables. These maps seem to be more stable and less prone to fail in predicting presence than those derived directly from the observed data.Los mapas de distribución son herramientas clave para la gestión medioambiental y los análisis biogeográficos. Pero el éxito en las predicciones de distribución espacial es limitado cuando se dispone de datos imprecisos de la presencia/ausencia. Tanto falsas ausencias como falsas presencias pueden estar relacionadas con desviaciones locales del equilibrio (por ejemplo, extinciones temporales o colonizaciones no exitosas). Además, las falsas ausencias pueden surgir de un esfuerzo de muestreo limitado. Aquí se explora una estrategia analítica para obtener información adicional sobre el patron de presencia/ausencia de una especie diana a partir de la presencia/ausencia de otras especies en la comunidad. La logica es simple: la especie diana debería tener una mayor probabilidad de presencia en un punto si una muestra de este punto es faunísticamente muy similar a las muestras de otros puntos donde la especie ha sido detectada. Por tanto, primeros se modela la presencia/ausencia de la especie diana en función de la similaridad faunística entre puntos. En segundo lugar, los datos observados para la especie diana son reajustados en función de la probabilidad esperada de presencia: las presencias observadas en puntos con probabilidad de presencia muy baja son interpretadas como presencias inestables, y recodificadas como ausencias. De manera similar, las ausencias en puntos con probabilidad de presencia muy elevada son interpretadas como falsas ausencias, y recodificadas como presencias. En el caso experimental estudiado, el procedimiento de recodificación esta basado en los datos de presencia/ausencia de 174 especies, abarcando un abanico taxonómico muy amplio (caracoles terrestres, coleópteros, arañas e isópodos). El mapa de distribución de celdas de 1 km2 del coleóptero endémico Phylan semicostatus es modelado a partir de estos datos. El mapa de distribución es elaborado a partir de cuatro variables medioambientales, usando una estrategia analítica basada en algoritmos genéticos (GARP). Los mapas obtenidos con los datos recodificados parecen ser mas estables y menos susceptibles de fallar en sus predicciones que los mapas elaborados directamente con los datos originales