Belfort D.R.,Campus Universitario Lagoa Nova |
Catunda S.Y.C.,Campus Universitario Lagoa Nova |
Aboushady H.,University Pierre and Marie Curie
Microelectronics Journal | Year: 2017
In this paper, we present the design and implementation of an RF bandpass ΣΔ modulator where the loop filter is a 4th order capacitively-coupled LC filter. A design methodology using coupling capacitor and the feedback Finite Impulse Response Digital-to-Analog Converter (FIRDAC) coefficients in order to obtain the desired Noise Transfer Function (NTF) is presented. The proposed capacitively-coupled bandpass LC ΣΔ is implemented in a 130 nm CMOS process. The fabricated chip, operating under a supply voltage of 1.2 V, has a varying center frequency range of 400–442 MHz with a corresponding sampling frequency range of 533–589 MHz. A maximum Signal-to-Noise Ratio (SNR) of 50 dB in a 4.5 MHz bandwidth for a power consumption of 20 mW was achieved. The effect of the clock jitter on the Analog-to-Digital Converter (ADC) performance is measured and presented. © 2017 Elsevier Ltd
Nascimento L.O.,Campus Universitario Lagoa Nova |
Nascimento L.O.,Federal University of Pará
Brazilian Journal of Physics | Year: 2017
A brief introduction to topological phases is provided, considering several two-band Hamiltonians in one and two dimensions. Relevant concepts of the topological insulator theory, such as: Berry phase, Chern number, and the quantum adiabatic theorem, are reviewed in a basic framework, which is meant to be accessible to non-specialists. We discuss the Kitaev chain, SSH, and BHZ models. The role of the electromagnetic interaction in the topological insulator theory is addressed in the light of the pseudo-quantum electrodynamics (PQED). The well-known parity anomaly for massless Dirac particle is reviewed in terms of the Chern number. Within the continuum limit, a half-quantized Hall conductivity is obtained. Thereafter, by considering the lattice regularization of the Dirac theory, we show how one may obtain the well-known quantum Hall conductivity for a single Dirac cone. The renormalization of the electron energy spectrum, for both small and large coupling regime, is derived. In particular, it is shown that massless Dirac particles may, only in the strong correlated limit, break either chiral or parity symmetries. For graphene, this implies the generation of Landau-like energy levels and the quantum valley Hall effect. © 2017, Sociedade Brasileira de Física.
Kathirithamby J.,University of Oxford |
Hayward A.,University of Oxford |
Mcmahon D.P.,University of Oxford |
Ferreira R.S.,University of Paris 13 |
And 3 more authors.
Systematic Entomology | Year: 2010
The family Myrmecolacidae (Strepsiptera) exhibit the unusual phenomenon of sexually dimorphic host relationships known as heterotrophic heteronomy, whereby males parasitize ants and females parasitize grasshoppers, crickets and mantids. It has therefore been impossible phenotypically to match male Myrmecolacidae to their conspecific females: the male and female of only one species have so far been unequivocally matched, and this was by molecular characterization. Here we report another match of a male and its conspecific female: by comparison of the CO1 and 18S genes of male Myrmecolax incautus Oliveira and Kogan, which parasitizes a ponerine ant from French Guyana, and a female strepsipteran, which parasitizes a mantid from Brazil. The male M. incautus is redescribed, and the first descriptions of the neotenic female, the male cephalotheca and the first instar larva are given. We also report for the first time dimorphic hosts of the male and the female M. incautus, and describe for the first time, the behaviour of stylopized ants. © 2009 The Authors. Journal compilation © 2009 The Royal Entomological Society.
Manzan M.F.,Federal University of Rio Grande do Norte |
Lopes P.F.M.,Campus Universitario Lagoa Nova |
Lopes P.F.M.,FIFOFisheries and Food Institute
Environmental Monitoring and Assessment | Year: 2014
Fishers’ local ecological knowledge (LEK) is an additional tool to obtain information about cetaceans, regarding their local particularities, fishing interactions, and behavior. However, this knowledge could vary in depth of detail according to the level of interaction that fishers have with a specific species. This study investigated differences in small-scale fishers’ LEK regarding the estuarine dolphin (Sotalia guianensis) in three Brazilian northeast coastal communities where fishing is practiced in estuarine lagoons and/or coastal waters and where dolphin-watching tourism varies from incipient to important. The fishers (N = 116) were asked about general characteristics of S. guianensis and their interactions with this dolphin during fishing activities. Compared to lagoon fishers, coastal fishers showed greater knowledge about the species but had more negative interactions with the dolphin during fishing activities. Coastal fishing not only offered the opportunity for fishers to observe a wider variety of the dolphin’s behavior, but also implied direct contact with the dolphins, as they are bycaught in coastal gillnets. Besides complementing information that could be used for the management of cetaceans, this study shows that the type of environment most used by fishers also affects the accuracy of the information they provide. When designing studies to gather information on species and/or populations with the support of fishers, special consideration should be given to local particularities such as gear and habitats used within the fishing community. © 2014, Springer International Publishing Switzerland.
Manzan M.F.,Federal University of Rio Grande do Norte |
Lopes P.F.M.,Campus Universitario Lagoa Nova |
Lopes P.F.M.,FIFO Fisheries and Food Institute
Ocean and Coastal Management | Year: 2016
Research on cetacean behavior is challenging because it happens mostly underwater. Fishermen, however, spend a good deal of their time in the water, and can bring new information about the behavior of aquatic species, especially if their knowledge can be extracted from sociocultural biases. We investigated how the habitat, distribution, seasonality, group size, and resting, reproductive and feeding behavior of the estuarine dolphin (Sotalia guianensis) perceived by small-scale fishermen is affected by their education, experience, fishing habitat, and the extent of dolphin watching tourism. We interviewed 116 fishermen in routine contact with populations of S. guianensis in NE Brazil regarding dolphin behavior and compared their responses to available literature. Most fishermen correctly reported the habitat, distribution, seasonality, and feeding behavior. Notably, education and experience, but not tourism, were related to a more detailed perception of behavior. Fishermen who used predominantly coastal waters or mixed environments had a more detailed knowledge of S. guianensis behavior than the ones fishing in estuarine lagoons. Moreover, the results provide new insights into the dolphin's reproductive behavior and possible migration patterns. The results highlight the need to consider the effects of cultural biases on fishermen's knowledge and that fishermen may provide information on cetaceans that could be used in management and conservation when scientific sources are missing or need to be complemented. © 2016 Elsevier Ltd
Soto-Adames F.N.,University of Illinois at Urbana - Champaign |
Bellini B.C.,Campus Universitario Lagoa Nova
Florida Entomologist | Year: 2015
Lepidonella is a small genus of scaled Paronellidae comprising 12 species distributed mainly across the Ethiopian, Oriental and Australian biogeographic regions. Most species are poorly described by current standards and little is known about their dorsal chaetotaxy. Previous observations of the chaetotaxy of the second and third abdominal segments led to suggestions that Lepidonella may be more closely related to Lepidocyrtus than to other paronellids, thus rendering Paronellidae polyphyletic. Here we describe the complete dorsal chaetotaxy of the Neotropical species, Lepidonella incerta (Mari Mutt, nec Handschin), and Lepidonella zeppelinii sp. nov., to evaluate the position of Lepidonella among genera of scaled Paronellidae. The abundant, largely undifferentiated chaetotaxy of L. incerta and L. zeppelinii sp. nov. suggests a basal position for Lepidonella among scaled Paronellidae. Putative synapomorphies of the chaetotaxy of the head and metathorax supporting the monophyly of Lepidonella lead us to conclude that most similarities in chaetotaxy between New World Lepidonella and Lepidocyrtus represent symplesiomorphies. We also conclude that Paronellidae s. lat. (i.e., including Cyphoderinae) is derived from an Orchesellinae or Heteromurini-like species and is sister to Entomobryinae. In addition, we describe L. zeppelinii sp. nov. from Brazil, the first member of the genus described for South America, we propose a new name, L. marimuti n. name, for L. incerta (Mari Mutt), which is a junior homonym of L. incerta (Handschin), transfer to the genus Trogolaphysa two species previously assigned to Lepidonella, and provide an identification key to the species of Lepidonella of the world.
Valenca M.M.,Campus Universitario Lagoa Nova
Habitat International | Year: 2015
This paper reviews recent developments regarding social housing policies in Hong Kong and the UK. Underlying the analysis is the fact that, during the last 40 years or so, both countries have been major global players in financial markets and thus pursued aggressive market-driven approaches to economic development. Notwithstanding that fact, each followed a different direction regarding housing policy reforms in the period. In Hong Kong (HK), the system of public housing provision was expanded; in the UK, the system of housing provision was scaled down. The argument being developed here is that a pro-public housing approach in HK should not be seen as a threat to capitalism in any way or measure. On the contrary, land development as well as land-originated fiscal revenues is a crucial part of HKSAR government's revenues. In the UK, this is no different. The return (through various forms of privatization) of the public housing stock (Council housing) to private hands (homeowners and housing associations) meant also to enhance businesses, in particular the mortgage and real estate markets. In both cases, there were also clear political reasons that justify developments in housing policy. The idea that Council housing served as a stage in the passage from a time when housing was predominantly provided in a largely unregulated private-rental market to a time when most people became homeowners is also discussed. This was what defined the 'modernization' of housing in the UK. The of 'residualization' was adopted to discuss the UK case. One important question is to know whether Hong Kong will follow the same path of 'modernization' as the UK, in the future. So far, HK has resisted; public housing has been 'resilient', ensured by a proper repair and maintenance policy, redevelopment and production of new housing throughout the last decades. Resilience is also granted by people's recognition and attachment to public housing and low stigmatization. More importantly, public provision of housing continues to be regarded, in both countries, as a necessary development to grant quality of life and a better distribution of income, avoiding the sharpening of social and territorial segregation, gentrification and stigmatization. © 2015 Elsevier Ltd.
Gomes-Neto S.,Federal University of Rio Grande do Norte |
Gomes-Neto S.,Campus Universitario Lagoa Nova |
Carvalho B.M.,Campus Universitario Lagoa Nova
VISAPP 2014 - Proceedings of the 9th International Conference on Computer Vision Theory and Applications | Year: 2014
This paper examines a generalized version of Preemptive RANSAC for visual motion estimation. The approach described employs the BRUMA function for dealing with varying block sizes and the percentages of hypotheses to be removed during the hypotheses rejection phase. The generation of a flexible number of hypotheses is also performed in order to balance the preemption scheme. Experiments were performed for both forward and side-wise motions in synthetic environment by using simulation and the ground-truth used to compare the Standard Preemptive RANSAC and its generalized version. Simulations confirmed that the quality of the results produced by the Standard Preemptive RANSAC degrade as the hardware resources used are decreased, as opposed to the results produced by the Generalized Preemptive RANSAC, with the results of the Standard Preemptive RANSAC having errors up to eleven times larger than the Generalized Preemptive RANSAC.
Galvao S.B.,Federal University of Rio Grande do Norte |
Lima A.C.,Campus Universitario Lagoa Nova |
De Medeiros S.N.,Campus Universitario Lagoa Nova |
Soares J.M.,UERN |
Paskocimas C.A.,Federal University of Rio Grande do Norte
Materials Letters | Year: 2014
Rod, platelet and ellipsoidal nanostructures of BaFe12O 19 have been synthesized by the Pechini method followed by heat treatment. The produced samples were heat treated at 900 C for different hours and characterized by X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and vibrating sample magnetometry. The results showed that the particle size and morphology vary with the time of heat treatment. The samples consisting of nanoparticles with different morphologies exhibited plateaus in the magnetic hysteresis loops. © 2013 Elsevier B.V.
Sales R.F.D.,Campus Universitario Lagoa Nova |
Ribeiro L.B.,Campus Universitario Lagoa Nova |
Ribeiro L.B.,Federal University of Vale do São Francisco |
Jorge J.S.,Campus Universitario Lagoa Nova |
Freire E.M.X.,Campus Universitario Lagoa Nova
Phyllomedusa | Year: 2011
We studied the use of spatial, temporal, and thermal resources by the Neotropical lizard Ameiva ameiva during rainy and dry seasons in a caatinga (xerophilous open forests) environment in northeastern Brazil. Lizards used the vegetation habitats and microhabitats in the ground, but never were seen in the rocky habitat. Adults usually used the arboreal-shrubby habitat, whereas juveniles were sighted more often in the shrubby-herbaceous habitat. Ontogenetic differences in spatial use seem to be linked to different thermal needs between age groups owing to differences in body size. Body temperatures were significantly higher in juveniles than in adults. Most teiid species have elevated body temperatures, usually above 37oC, and are active during the hottest times of day, as was observed for A. ameiva in this study. Seasonality influenced habitat use and daily activity periods of adults, but not body temperatures. We verified annual fluctuations in adult abundance, with a decline of active lizards in the dry season; this phenomenon may be related to aestivation and/or increased mortality rate during the driest months. © 2011 Departamento de Ciências Biológicas - ESALQ - USP.