Non-homogeneous Fabry-Pérot Antenna Design at Ku-band

A novel technique to design Fabry-Pérot antennas with non-homogeneous PRS is described. It takes advantage of a transmission line circuit model to efficiently obtain all necessary unit cell designs that satisfy the cavity resonance condition. This approach allows an increase in directivity for a given footprint without decreasing the bandwidth. Some design examples are presented, showing the evolution from a simple single-layer PRS to a non-homogeneous two-layers one. Through electromagnetic simulations, the latter one achieves an increase of about 3 dB in directivity while maintaining the bandwidth. This way, the gain-bandwidth product is improved from a value of 5 to almost 9, effectively raising the antenna efficiency.This work has been supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU) (Contrato Juan de la Cierva-Incorporación) under Grant IJC2018-038440-I and by the MCIU/AEI/FEDER (Programa Estatal de I+D+i Orientada a los Retos de la Sociedad) under grant RTI2018-097098-J-I00. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Activity patterns of the vulnerable guiña (Leopardus guigna) and its main prey in the Valdivian rainforest of southern Chile

The guiña (Leopardus guigna) is a small felid found primarily in temperate mixed forests of southern Andean and coastal ranges in Chile and Argentina. It is considered a vulnerable species, and is one of the least studied felids in the world. In this study our main aim was to document the relationship between the activity pattern of the guiña and that of its main prey in the Valdivian rainforest (Comau Fjord, southern Chile) using a camera-trap survey. We documented the activity patterns of small mammals and two ground-foraging bird species, as these have been previously cited as the main prey of this felid. Guiñas showed two nocturnal activity peaks, at the beginning and the end of the night, and a weak peak of activity at midday. Small mammals consistently revealed nocturnal activity, whereas both birds were strongly diurnal. Our results revealed a high overlap between the activity patterns of guiñas and small mammals, whereas this was negligible for the bird species. These findings support the idea that small mammals are guiñas' preferred prey in the Valdivian rainforest. Our study contributes to the understanding of the temporal relationships between the guiña and its prey, and may help to design effective management strategies to conserve this vulnerable felid.This study was funded by the agreement between Fundación Endesa, Fundación San Ignacio del Huinay and CSIC, and the Spanish Organismo Autónomo Parques Nacionales (project OAPN 352/2011). M. Delibes-Mateos was supported a JAE-doc contract (Programa Junta para la Ampliación de Estudios), funded by CSIC and the European Social Fund and J. Caro had a postdoctoral contract jointly financed by the ESF and the Junta de Comunidades de Castilla-La Mancha (JCCM, Spain), in the framework of the Operational Programme FSE 2007–2013.Peer Reviewe

Caracterización de la comunidad de mamíferos de un área remota del sur de Chile mediante el uso combinado de metodologías

[ES]: Actualmente se desconoce la presencia y distribución de los mamíferos en muchos lugares remotos, pese a que suelen ser lugares ricos en biodiversidad. El objetivo de este trabajo fue caracterizar la comunidad de mamíferos terrestres de la Reserva de Huinay, sur de Chile, mediante tres metodologías: i) encuestas a residentes y visitantes de la zona (n=42); ii) transectos de indicios (excrementos, huellas, etc; se recorrieron 80 km en total); y iii) foto-trampeo (se colocaron 18 cámaras-trampa con un esfuerzo total de 590 trampas-día). Se identificaron 13 especies de mamíferos terrestres. El pudú (Pudu puda), la güiña (Leopardus guigna) y el quique (Galictis cuja) fueron las únicas identificadas mediante los tres métodos. Nuestros resultados sugieren que diferentes metodologías pueden ser complementarias para determinar la presencia y distribución de las especies en áreas remotas.[EN]: The presence and distribution of mammals in remote areas are currently poorly known, although these areas are usually rich in biodiversity. The main objective of this study was to characterize the terrestrial mammal community within the reserve of Huinay, southern Chile, using three methodologies: i) questionnaires to residents and visitors to the area (n=42); ii) transects of mammals’ presence (scats, tracks, etc; the total length of transects was 80 km); iii) camera-trapping (18 camera-traps were set with a total sampling effort of 590 trap-days). A total of 13 species of mammals were identified, and only three of them (pudu, Pudu puda, kodkod, Leopardus guigna and lesser grison, Galictis cuja) were recorded with all the methods employed. Our results suggest that different methodologies can complement each other for surveying species presence and distribution in remote areas.Este estudio ha sido financiado por el acuerdo entre la Fundación Endesa, Fundación San Ignacio del Huinay y el CSIC. M. Delibes-Mateos está financiado actualmente por la Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía y el 7º programa marco de la Unión Europea para investigación, desarrollo tecnológico y demostración bajo el acuerdo 267226. J. Caro tuvo un contrato postdoctoral financiado por la Junta de Comunidades de Castilla-La Mancha y el FSE en el marco del programa operacional FSE 20072013.Peer Reviewe

Feeding habits of Black-billed Magpie during the breeding season in Mediterranean Iberia: the role of birds and eggs

[Capsule]: Feeding habits of the Black-billed Magpie are of interest for researchers, conservationists and hunters since magpies are considered as predators of eggs and chicks of both songbirds and gamebirds. [Aims]: To characterize the feeding habits of magpies during their breeding season in agricultural environments of central Spain, and to assess the occurrence and incidence of birds and eggs in the magpie's diet. [Methods]: Diet was determined by the analysis of gizzard contents from 118 culled magpies. The diet was described as the frequency of occurrence (FO) and the percentage of volume (VOL) of a certain food item and for each gizzard. [Results]: Magpies presented a generalist diet, which included a wide range of foods. Arthropods and cereal seeds were the most frequently consumed food groups (FO > 60%). Eggs and birds were consumed only occasionally (FO < 6% and 17%, respectively; percentage of volume, VOL < 4%). [Conclusion]: Our findings suggest that other birds and their eggs do not represent an important food for magpies in Mediterranean agricultural environments under the conditions found during this study. Nevertheless, more complex studies in different scenarios (i.e. different population sizes of magpies and prey), and over longer temporal scales, are still necessary to clarify this controversial issue.The study was funded by Consejería de Medio Ambiente of Junta de Comunidades de Castilla-La Mancha (Project PREG-05-23). F. Díaz-Ruiz holds a postdoctoral contract financed by the European Social Fund (ESF) and the Junta de Comunidades de Castilla-La Mancha (Operational Programme FSE 2007/2013). M. Delibes-Mateos is supported by the Talentia Postdoc Program launched by the Andalusian Knowledge Agency, co-funded by the European Union’s Seventh Framework Program, Marie Skłodowska-Curie actions (COFUND – Grant Agreement n° 267226) and the Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía.Peer Reviewe

Drivers of red fox (Vulpes vulpes) daily activity: prey availability, human disturbance or habitat structure?

Daily activity patterns in mammals depend on food availability, reproductive stage, habitat selection, intraspecific interactions and predation risk, among other factors. Some mammals exhibit behavioral plasticity in activity patterns, which allows them to adapt to environmental changes. A good example of this can be found in the red fox Vulpes vulpes. This species is adapted to living in highly humanized environments, where it is often culled because it may affect human interests (e.g. through the consumption of game species or livestock). We assessed the potential main drivers of the daily activity patterns of the red fox in 12 Iberian Mediterranean areas through the use of camera traps. Among drivers, we considered main prey availability (European wild rabbits Oryctolagus cuniculus), degree of human disturbance (e.g. distance to human settlements, and intensity of predator control) and habitat structure. Our results revealed a predominantly crepuscular and nocturnal activity of foxes with local variations. Although overall fox activity increased with rabbit availability, the temporal overlap with prey activity was on average low, because foxes increased activity when rabbits decreased theirs (twilight-night). Red fox activity rhythms seemed to be determined by human presence where human disturbance is high. In addition, diurnal activity decreased in areas with higher levels of human disturbance (closer to human settlements and high predator control intensity) and increased in dense habitats. Our study shows that daily activity patterns of highly adaptable species are determined by several interacting drivers, resulting in complex behavioral patterns. This suggests that further ecological studies should consider different factors simultaneously for a better understanding of daily activity patterns of wildlife in different landscapes.This study was funded by projectsCGL2009-10741 (Spanish Ministry of Science and Innovation and EU-FEDER funds); HUNTing for Sustainability(212160, FP7-ENV-2007-1), and OAPN352/2011 (Organismo Autónomo de Parques Nacionales, Spain). F. Díaz-Ruiz and J. Caro enjoyed postdoctoral contracts financedby the European Social Fund (ESF) and the Junta de Comunidades de Castilla-La Mancha (Operational Programme FSE 2007/2013). M. Delibes-Mateos is currently funded by Consejería de Economía, Innovación, Ciencia y Empleo of Junta de Andalucía, and the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement 267226.Peer Reviewe

Physical Implementation of Leaky-Wave Antenna with Engineered Aperture Distribution Based on Bianisotropic Huygens Metasurfaces

A methodology based on omega-type bianisotropic Huygens’ metasurfaces is presented to control the aperture field distribution of leaky-wave antennas. The studied structure is a parallel-plate waveguide with the top plate replaced by a metasurface. Previous works achieved independent control of the phase constant and the leakage factor, but they were constrained to be constant. The required theoretical extensions to overcome this limitation are presented in this work, thus enabling the design of arbitrary radiation patterns. A slowly varying amplitude approximation approach is employed to satisfy Maxwell’s wave equation and obtain the relation between the horizontal and vertical wavenumbers. In addition, a semianalytical algorithm able to predict near-field coupling effects is applied in the microscopic design of the metasurface unit cells. Two designs are carried out with real unit cells, presenting different aperture configurations. Finally, electromagnetic simulations validate the methodology with an excellent agreement without any further full-wave optimization.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Citas herpetológicas en Castilla-La Mancha obtenidas mediante trampeo fotográfico

Este trabajo ha sido financiado por: Comisión Europea (7th Framework Programme for Research and Technological Development) a través del proyecto HUNT (212160, FP-ENV-2007-1); Organismo Autónomo de Parques Nacionales a través del proyecto Factores de la coexistencia de mesocarnívoros en Parques Nacionales de ambiente mediterráneo (352/2011); y por el Plan Nacional I+D+I a través del proyecto Interacciones ecológicas en comunidades de carnívoros ibéricos: métodos de estudio y efecto de los factores climáticos y la gestión cinegética (CGL2009-10741). J.C. tiene una beca post-doctoral de la Junta de Comunidades de Castilla-La Mancha (Programa FSE 2007-2013).Peer reviewe

High-Resolution Optical Thickness Measurement Based on Electro-Optic Dual-Optical Frequency Comb Sources

We propose an optical thickness measurement device based on electro-optic dual-optical frequency combs (dual-OFCs). Optical frequency combs (OFCs) are light sources that provide an optical signal consisting of many equidistant monochromatic tones. In this paper, we present an agile dual-OFC architecture with adjustable frequency separation of the comb modes and total frequency span, allowing high-resolution measurements of the thickness of transparent thick samples. This architecture is based on a single continuous-wave laser diode and external electro-optic devices to implement the dual-comb sensor, allowing easy control of the optical spectrum of the interrogation source (dual-OFC). As it is characteristic of dual-OFC systems, the optical transmittance function of the sample (etalon) is directly translated to the radiofrequency domain, where detection, demodulation, and processing of signals are performed. The shift in the complexity of implementation from the optical to the electronic domain yields many advantages, as acquisition and signal processing are made independently on the optical characteristics of the sample (thickness).This work was supported by the Spanish Ministry of Economy and Competitiveness under the RTC-2015-4205-4 Salicar and TEC-2014-52147-R Mossi grants

Estudio del desalineamiento entre capas para reducir el acoplamiento en metasuperficies.

La obtención de celdas unidad es un factor clave en el diseño de metasuperficies. Éstas suelen estar compuestas por varias capas de geometrías metálicas apiladas a través de sustratos. Para sintetizar unos parámetros S dados a partir de estas celdas, suelen usarse modelos circuitales sencillos. Sin embargo, éstos quedan comúnmente invalidados por los efectos del acoplamiento mutuo entre capas, lo que hace necesario recurrir a otros modelos más complejos y demandantes. Con el objetivo de evitarlo, este trabajo analiza el efecto del desalineamiento entre capas de las celdas en la disminución del acoplamiento mutuo. Para ello, se analiza detalladamente esta técnica en una celda de ejemplo, y luego se prueba en dos metasuperficies reales, comprobándose así su efectividad y limitaciones.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech