Electronically Tunable Phase Response for Phased array Patches

The design and prototyping of radiating elements with tunable phase response, for reconfigurable patch array antennas, is presented. Different options are found in the technical literature to obtain feasible reconfigurable array antennas: placing the active circuitry in the transmission lines or directly over the radiating element, obtaining the desired phase shift for each radiating element of the array. In this reported work, the second option is selected and active radiating elements at 12 GHz are designed and prototyped

Resonance in Asymmetric Warped Geometry

We study the spectrum of an asymmetric warped braneworld model with different AdS curvatures on either side of the brane. In addition to the RS-like modes we find a resonance state. Its mass is proportional to the geometric mean of the two AdS curvature scales, while the difference between them determines the strength of the resonance peak. There is a complementarity between the RS zero-mode and the resonance: making the asymmetry stronger weakens the zero-mode but strengthens the resonance, and vice versa. We calculate numerically the braneworld gravitational potential and discuss the holographic correspondence for the asymmetric model.Comment: 17 pages, 9 figures; v2 references with comments added; v3 two references added, JHEP versio

Ku Band transmitarray lens for microwave applications

In this document a microstrip constrained lens device for Ku band, for microwave purpose, is presented. This paper offers an overview of artificial lens-type devices and the proposed transmitarray lens is thoroughly studied in terms of design and manufacturing, with architecture discussion and selection, along with the design, manufacturing and validation of all the forming components of the transmitarray (transmission circuits, radiating elements, etc.). Each element is properly characterized and assembled properly in the complete transmitarray prototype. Eventually, radiation pattern measurements as well as gain and directivity values, are provided to show the proper behaviour of the proposed transmitarray lens

Product CFTs, gravitational cloning, massive gravitons and the space of gravitational duals

The question of graviton cloning in the context of the bulk/boundary correspondence is considered. It is shown that multi-graviton theories can be obtained from products of large-N CFTs. No more than one interacting massless graviton is possible. There can be however, many interacting massive gravitons. This is achieved by coupling CFTs via multi-trace marginal or relevant perturbations. The geometrical structure of the gravitational duals of such theories is that of product manifolds with their boundaries identified. The calculational formalism is described and the interpretation of such theories is discussed.Comment: Latex, 25 pages. (v2) Minor corrections and references adde

Estudio morfométrico de las abejas andaluzas

The biological and behavioral characteristics of the iberian bees are much less known than the other european races. This paper studies the morphological characteristics (Proboscis length; Forewing length; Forewing width; Cubital vein a; Cubital vein b; Cubital index a/b; Hindwing length; Hindwing width; Femur length; Tibia length; Metatarsus length; Metatarsus width; Width of tomentum at tergite 4; Pigmentation of tergite 3) of bees used in andalusian apiculture. Our results coincide with those described for Apis mellifera iberica.Las características biológicas y de comportamiento que presentan las abejas de la península ibérica son menos conocidas que las que presentan otras razas europeas. En el presente trabajo estudiamos las características morfológicas (longitud de la proboscis; longitud del ala delantera derecha; anchura del ala delantera derecha; vena cubital a; vena cubital b; índice cubital a/b; longitud del ala trasera derecha; anchura del ala trasera derecha; longitud del fémur; longitud de la tibia; longitud del metatarso; anchura del metatarso; longitud del tomentun del terguito 4º y pigmentación del terguito 3º) que presentan las abejas empleadas en la apicultura andaluza. Nuestros resultados coinciden con los descritos para Apis mellifera iberica

Artificial insemination of queen bees

The race commonly used by spanish beekeepers is Apis mellifera iberica. Up to date, any selection process has been carried out with this race, and a lot of characteristics in the colony can be improved. Artificial insemination is a technique used in order to control genetic origin, and open a way to control those tasks usefull for beekeepers, both productive (honey, pollen or royal jelly production...) o linked with behaviour (agresiveless, short tendency to swarming, natural resistance to disesases...)Apis mellifera iberica es la raza de abeja que utilizan los apicultores actualmente en España. Las características de esta abeja aún están por mejorar, ya que hasta el momento no se ha desarrollado ningún programa de selección que la afecte. La inseminación artificial es la técnica que se utiliza para controlar el origen genético de los progenitores, pudiendo seleccionar aquellos caracteres que sean más interesantes para el apicultor, ya sean estos de tipo productivo (kilogramos de miel, polen, jalea real, etc) o de comportamiento (menor agresividad, menor tendencia a la enjambrazón, resistencia a enfermedades, etc)

Abejas, apicultura y el nuevo mundo

In the New World, some stingless bees were kept by the native population. In Central America, maya beekeepers worked with Mellipona beecheii, in Yucatan and adjacent regions. The arrival in North America of the first beehives was in 1691 and it were sent to Virginia by the Council of the Virginia Company in London. Concerning the introduction to Central and South America the first ones arrived from Spain and Portugal towards the end of the 18th century, probably to Brazil. Prior to 1800, the european breeds taken to America were probably Apis mellifera mellifera and Apis mellifera iberica. At the turn of the century, a new european breed was imported from Italy (Apis mellifera ligustica). American apiculture has used these breeds and crossbreeds virtually up to the present day. In 1956, tropical african queens of the breed Apis mellifera scutellata were introduced to Brazil. Its crosses involving european breeds gave rise to africanized bees, which have spread over almost the whole of South, Central and North America.Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. Los nativos del Nuevo Mundo utilizaban algunas abejas sin aguijón. En América Central los apicultores mayas trabajaron, en el Yucatán y regiones adyacentes, con Mellipona beecheii. La llegada a América del Norte de las primeras colmenas se produjo en 1691. Fueron enviadas a Virginia desde Inglaterra por la Virginia Company. Las primeras colmenas enviadas a América Central y del Sur, probablemente a Brasil, a finales del siglo XVIII, procedían de España y Portugal. Antes de 1800 las razas europeas llevadas a Amé-rica fueron, probablemente, Apis mellifera mellifera y Apis mellifera iberica. A fin de siglo se introduce otra (Apis mellifera ligustica) procedente de Italia. La apicultura americana ha empleado las razas mencionadas y sus cruces, hasta nuestros días. En 1956 se introdujeron en Brasil reinas de Apis mellifera scutellata, procedentes de Africa tropical. Las abejas procedentes de su cruce con razas europeas, “africanizadas”, se han extendido por casi la totalidad del continente americano

Grooming in Apis mellifera iberica

We checked grooming in 8 colonies of the race Apis mellifera iberica. We studied fallen mites on plastic sheets put on the bottom board. Tests were repeated 12 times. Grooming was detected in A. m. iberica race: 5.07 percent of living mites and 50.85 percent of died mites were injuried. Damages were present in legs and body. Grooming can be an important character for selection of tolerant bees to varroosis.El principal problema de índole patológico de la apicultura actual es una parasitosis provocada por el ácaro Varroa jacobsoni Oud. En los últimos tiempos se han descrito comportamientos en diferentes razas de abejas capaces de detectar, morder y eliminar los parásitos. A estos comportamientos se les conoce como grooming, y es una posible vía para la selección de abejas tolerantes a enfermedades, aunque no la única. En nuestro trabajo hemos descrito este comportamiento en Apis mellifera iberica, la raza de abeja habitualmente usada en nuestra apicultura. Los parásitos eran recogidos en bandejas situadas en el fondo de las colmenas. El 5,07 p.100 de los parásitos recogidos vivos y el 50,85 p.100 de los muertos presentaron daños. Los daños se repartieron entre los apéndices y el idiosoma. Esto abre una camino a la esperanza de mejorar la respuesta de autodefensa en la mencionada raza frente al parásito

Queen rearing of apis mellifera iberica

Apis mellifera iberica is the spanish bee race mostly used by breeders. Queen rearing is necessary for genetic selection . Our research team uses the Doolittle method; Mainly it is based on transfering young (a few hours old) worker larvae to artificial queen cells. Larvae are reared in queenless colonies. After sealed, queen cells are kept in an incubator chamber. Mean percentage of alive queens during a season reaches 80 p.100.Apis mellifera iberica es la abeja habitualmente usada por los apicultores en España. Para la mejora de esta raza es esencial la cría controlada de abejas reinas. Nuestro equipo de investigación emplea el método Doolittle, consistente en el transvase de larvas de obreras con pocas horas de vida a celdillas reales artificiales. Estas larvas son criadas en colmenas huérfanas hasta su operculación y, posteriormente, mantenidas en incubadoras hasta el nacimiento. El éxito medio alcanzado a lo largo de la temporada es del 80 p.100