Entity

Time filter

Source Type

Curitiba, Brazil

Soto J.,Federal University of Paran | Soto J.,Federal University of Parana | Queiroz S.,Federal University of Parana | Queiroz S.,Federal University of Amazonas | And 2 more authors.
IEEE Wireless Communications | Year: 2013

Primary user emulation attacks (PUEAs) are one of the most damaging threats in cognitive radio networks. Malicious or selfish secondary users pretend legitimate primary users to profit from the opportunistic use of the licensed frequency spectrum. Since cognitive radio importance has enhanced as an approach to spectral efficiency and to diminish the negative effects of wireless network scalability, approaches for PUEAs defense have arisen, evolving their architectural strategy, node¿s operation and analysis design. This article overviews recent achievement in PUEA defenses and presents a classification. Persistently unsolved challenges in the field are highlighted, and a framework for tackling one of the main challenges-the lack of flexibility to address this highly compromising attack-is outlined, promoting progress in the art of PUEA defense. As proof of concept, results present improvements in attack analysis employing flexible and multidimensional techniques on a case study. Finally, open issues and future directions are emphasized. © 2013 IEEE. Source


Dos Santos-Mallet J.R.,Oswaldo Cruz Foundation | Muller G.A.,Federal University of Santa Catarina | Muller G.A.,Federal University of Paran | Gleiser R.M.,National University of Crdoba | And 4 more authors.
Journal of the American Mosquito Control Association | Year: 2010

The eggs of Aedes scapularis analyzed by scanning electron microscopy are black and elliptical in outline, measuring approximately 620.4 ± 16.74 μm long and 163.7 ± 16.90 m (n 10) wide, with an egg index (length/width ratio) of 3.79. The anterior extremity tapered abruptly from a width of 51.6 μm, while such tapering was more gradual at the posterior extremity, from a width of 61.4 m. The ventral surface of the chorionic coating presented cells with a tubular aspect containing tubercles in rows at a density of 5 to 9 per cell with 2 different sizes, the largest measuring 7.23 ± 0.98 m in a longitudinal diameter and the smallest 4.15 ± 0.53 μm (n 30). In the dorsal region, the external chorionic reticulum had a porous appearance, and its thickness ranged from 2.5 to 4.1 μm. Isolated tubercles presented wide variation per cell. In the central region of some chorionic cells were tubercles of greater diameter, characterized as central tubercles of 8.45 ± 0.67 μm, and around them 3 to 5 smaller tubercles measuring 2.57 ± 0.26 μm. The micropylar apparatus presented a collar with a very evident molding and edges with defined margins for the transition area and a thickness of around 11.1 μm. The micropyle disc margins were raised, measuring around 17.8 μm in diameter and 229 m in circumference. The micropyle orifice was very evident, with a diameter of 1.41 μm. © 2010 by The American Mosquito Control Association, Inc. Source


Smadja D.,University of Bordeaux 1 | Smadja D.,Cleveland Clinic | Reggiani-Mello G.,Cleveland Clinic | Reggiani-Mello G.,Federal University of Paran | And 2 more authors.
Journal Francais d'Ophtalmologie | Year: 2012

Purpose: To provide an overview of the clinical results of various ablation profiles and discuss their technical characteristics and limitations. Materials and methods: Literature review. Results: With the emergence of wavefront technology, new photoablation profiles have been developed, allowing for customization of refractive treatments and reduction of nocturnal visual symptoms, which adversely affect the reputation of refractive surgery. Over the past decade, several comparative studies have been published in the literature aiming to demonstrate either the superiority of wavefront-guided correction over conventional, or one laser platform over another. However, has an ideal treatment algorithm really emerged from these studies? Does one ablation profile clearly demonstrate superiority over another, in terms of visual performance? Conclusion: Despite technological advances as well as improved visual results for custom versus conventional photoablation, the promise of excellence in visual performance has not been achieved with these various technologies. The concept of an individualized eye model has emerged recently, based on an optical ray tracing algorithm, and could theoretically provide an ideal ablation profile, thus fulfilling the promise of "supernormal vision". © 2011 Elsevier Masson SAS. All rights reserved. Source


Carbajal Arizaga G.G.,University of Tijuana | Wypych F.,Federal University of Paran | Castilln Barraza F.,University of Tijuana | Contreras Lopez O.E.,University of Tijuana
Journal of Solid State Chemistry | Year: 2010

A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 , typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 . Thermal treatment at 150 °C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 . Intense NH stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH4(NH3)n] species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 basal distance) at pH=7, as well as a pure crystalline phase with 13.9 basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 °C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. © 2010 Elsevier Inc. All rights reserved. Source


Najafzadeh M.J.,Fungal Biodiversity Center | Najafzadeh M.J.,University of Amsterdam | Najafzadeh M.J.,Mashhad University of Medical Sciences | Sun J.,Guangzhou University | And 6 more authors.
Medical Mycology | Year: 2010

A new species of Fonsecaea, Fonsecaea nubica, morphologically similar to F. pedrosoi and F. monophora, is described using multilocus molecular data including AFLP profiles, sequences of the ribosomal internal transcribed spacers (ITS), and partial sequences of the cell division cycle (cdc42), β-tubulin (tub1) and actin (act1) genes. A phylogenetic approach was used to evaluate species delimitation. Topologies of the trees were concordant. Fonsecaea strains could be classified into three major entities, i.e., one representing Fonsecaea pedrosoi isolates, another consisting of strains of F. monophora, and a third, unnamed group comprising isolates mostly recovered from cases of chromoblastomycosis in South America and China. F. nubica is part of this latter group. Based on strains analyzed thus far, we have found that the pathologies of these three Fonsecaea species are somewhat different in that F. pedrosoi and F. nubica are preponderantly associated with chromoblastomycosis, while F. monophora may also act as a systemic opportunist in cases involving brain infections. The latter species is also the most frequently recovered of the three from environmental samples. © 2010 ISHAM. Source

Discover hidden collaborations