59 research outputs found
Effective Maxwell's equations in general periodic microstructures
We study the time harmonic Maxwell equations in a meta-material consisting of
perfect conductors and void space. The meta-material is assumed to be periodic
with period ; we study the behaviour of solutions in the limit and derive an effective system. In
geometries with a non-trivial topology, the limit system implies that certain
components of the effective fields vanish. We identify the corresponding
effective system and can predict, from topological properties of the
meta-material, whether or not it permits the propagation of waves
Study of four Neotropical species of tree crickets Oecanthus Serville, 1831 (Orthoptera, Gryllidae) using cytogenetic and molecular markers
Karyotypes in the worldwide subfamily Oecanthinae show variations in diploid number, chromosome morphology, and sex-chromosome system. This study described the chromosome set and phylogenetic relationships of four Neotropical species, Oecanthus lineolatus, O. valensis, O. pallidus, and O. pictus. We used classical cytogenetics and Bayesian Inference for phylogenetic reconstruction, using the mitochondrial genes COI, 12S rRNA, and 16S rRNA; and analyzed the phylogenetic patterns of changes in chromosome numbers, using ChromEvol. We observed differences in chromosome number among species and two different sex-chromosome systems. Oecanthus pictus showed 2n = 21, X0â/22, XXâ; O. lineolatus, 2n = 20, XYâ/XXâ; and O. valensis and O. pallidus, 2n = 18, XYâ/XXâ. The karyotype of Oecanthus was asymmetric, one group with large chromosomes and variation in heterochromatin distribution, and another with small acrocentric chromosomes. The phylogenetic tree recovered two main groups: one with the Palearctic species and another with species from different bioregions, but with low posterior probability. The Neotropical species grouped separately, O. valensis and O. pictus with Nearctic and Ethiopian species, and O. pallidus and O. lineolatus in another, well-supported clade. Together, the phylogenic and chromosome data suggest descending dysploidy events during the evolution of the group
Cultura polĂtica de la democracia en PerĂș y en las AmĂ©ricas, 2014 : gobernabilidad democrĂĄtica a travĂ©s de 10 años del BarĂłmetro de las AmĂ©ricas
El presente estudio es parte de un programa de investigaciones que el Proyecto de OpiniĂłn PĂșblica de AmĂ©rica Latina (LAPOP) viene llevando a cabo desde hace mĂĄs de dos dĂ©cadas. LAPOP es un consorcio de instituciones acadĂ©micas y de investigaciĂłn en las AmĂ©ricas, con sede central en Vanderbilt University, en Estados Unidos. En el proyecto LAPOP participan mĂĄs de 30 instituciones de toda la regiĂłn, cuyos esfuerzos tienen el propĂłsito de producir estudios cientĂficos, objetivos e independientes de opiniĂłn pĂșblica. Dichas investigaciones se enfocan principalmente en la mediciĂłn de actitudes y comportamientos polĂticos relacionados con la democracia y la calidad de vida
Understanding the chromosomal evolution in cuckoos (Aves, Cuculiformes): a journey through unusual rearrangements
The Cuculiformes are a family of over 150 species that live in a range of habitats, such as forests, savannas, and deserts. Here, bacterial artificial chromosome (BAC) probes (75 from chicken and 14 from zebra finch macrochromosomes 1â10 +ZW and for microchromosomes 11â28 (except 16)) were used to investigate chromosome homologies between chicken and the squirrel cuckoo ( Piaya cayana). In addition, repetitive DNA probes were applied to characterize the chromosome organization and to explore the role of these sequences in the karyotype evolution of P. cayana. We also applied BAC probes for chicken chromosome 17 and Z to the guira cuckoo ( Guira guira) to test whether this species has an unusual Robertsonian translocation between a microchromosome and the Z chromosome, recently described in the smooth-billed ani ( Crotophaga ani). Our results revealed extensive chromosome reorganization with inter- and intrachromosomal rearrangements in P. cayana, including a conspicuous chromosome size and heterochromatin polymorphism on chromosome pair 20. Furthermore, we confirmed that the Z-autosome Robertsonian translocation found in C. ani is also found in G. guira, not P. cayana. These findings suggest that this translocation occurred prior to the divergence between C. ani and G. guira, but after the divergence with P. cayana
Stridulatory file and calling song of two populations of the tropical bush cricket Eneoptera surinamensis (Orthoptera, Gryllidae, Eneopterinae)
Comparison of calling songs in three allopatric populations of Endecous itatibensis (Orthoptera, Phalangopsinae)
Three isolated populations of the cricket Endecous itatibensis Rehn, 1918 had been analyzed to test the hypothesis of divergence in the calling song estridulation and to discuss its implications in the speciation process. The song registers were obtained from specimens in CorumbataĂ, Piraciacaba and Itatiba cities, state of SĂŁo Paulo, Brazil. In the three analyzed populations, calling songs are composed by pairs of notes. Specimens from CorumbataĂ emit composed phrases with 3 to 18 pairs of notes, while those of Piracicaba and Itatiba have 1 to 3 pairs of notes. Inter- and intrapopulational variability in the frequencies of acoustic signals were detected. While recording the calling songs, other stridulations were registered, possibly from species of Orthoptera or Hemiptera. When the tapes were analyzed in the laboratory, it was verified that there was no overlap among the species' calling songs, in such a way that each species had their particular band of frequencies, avoiding interespecific acoustic competition
Adelosgryllus rubricephalus: a new genus and species of cricket (Orthoptera: Phalangopsidae)
Morphological characterization of the proventriculus of Gryllus assimilis Fabricius (Orthoptera, Gryllidae)
The proventriculus morphology of the cricket Gryllus assimilis Fabricius, 1775 is described using scanning electron microscopy and the correlation of this structure with the feeding habits briefly considered
Adelosgryllus rubricephalus: a new genus and species of cricket (Orthoptera: Phalangopsidae)
Um novo gĂȘnero e espĂ©cie de grilo falangopsĂdeo Adelosgryllus rubricephalus Ă© descrito. IlustraçÔes de espĂ©cimes macho e fĂȘmea e a descrição dos escleritos fĂĄlicos, assim como os cromossomos e a distribuição geogrĂĄfica conhecida sĂŁo relatados. Uma discussĂŁo sobre a posição taxonĂŽmica desse grilo dentro da famĂlia Phalangopsidae Ă© incluĂda.Adelosgryllus rubricephalus, a new genus and species of phalangopsid cricket are described. Illustrations of male and female specimens as well as descriptions of phallic sclerites, chromosomes and geographical known distribution are furnished. A discussion on the species taxonomic status of this cricket within the family is also included
FIGURE 2 in Anurogryllus Saussure, 1877 (Orthoptera: Gryllidae: Gryllinae) from southern Brazil: new species and new records
FIGURE 2. â Anurogryllus patos sp. nov. holotype general morphology. Aâhabitus, dorsal; Bâhabitus, ventral; Câhead and pronotum, dorsal; Dâhead and pronotum, lateral; Eâfemur III, lateral; Fâexternal tympanum in the tibia III; Ginternal tympanum in the tibia III; Hâright tegmen, dorsal; Iâsupra-anal plate, dorsal; Jâsubgenital plate, ventral
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