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Search Results: 1 - 10 of 16787 matches for " Rafael;Nascimento "
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On the Oblivious Transfer Capacity of Generalized Erasure Channels against Malicious Adversaries
Rafael Dowsley,Anderson C. A. Nascimento
Computer Science , 2014,
Abstract: Noisy channels are a powerful resource for cryptography as they can be used to obtain information-theoretically secure key agreement, commitment and oblivious transfer protocols, among others. Oblivious transfer (OT) is a fundamental primitive since it is complete for secure multi-party computation, and the OT capacity characterizes how efficiently a channel can be used for obtaining string oblivious transfer. Ahlswede and Csisz\'{a}r (\emph{ISIT'07}) presented upper and lower bounds on the OT capacity of generalized erasure channels (GEC) against passive adversaries. In the case of GEC with erasure probability at least 1/2, the upper and lower bounds match and therefore the OT capacity was determined. It was later proved by Pinto et al. (\emph{IEEE Trans. Inf. Theory 57(8)}) that in this case there is also a protocol against malicious adversaries achieving the same lower bound, and hence the OT capacity is identical for passive and malicious adversaries. In the case of GEC with erasure probability smaller than 1/2, the known lower bound against passive adversaries that was established by Ahlswede and Csisz\'{a}r does not match their upper bound and it was unknown whether this OT rate could be achieved against malicious adversaries as well. In this work we show that there is a protocol against malicious adversaries achieving the same OT rate that was obtained against passive adversaries. In order to obtain our results we introduce a novel use of interactive hashing that is suitable for dealing with the case of low erasure probability ($p^* <1/2$).
Evaluation of Larval Development of Dirofilaria immitis in Different Populations of Aedes aegypti and Aedes albopictus  [PDF]
Gílcia Aparecida de Carvalho, Rafael Trindade Maia, Rafael Antonio Nascimento Ramos, Carlos Fernando Salgueirosa de Andrade, Maria Aparecida da Gloria Faustino, Leucio Camara Alves
Open Journal of Veterinary Medicine (OJVM) , 2013, DOI: 10.4236/ojvm.2013.36045
Abstract: Dirofilaria immitis is an important nematode parasite commonly known as heartworm. This filarioid is transmitted by culicid vectors and primarily affects dogs, but other animals may also become infected, such as wild carnivores, cats and humans. The aim of the present study was to assess the development of D. immitis larvae in different culicid populations under laboratory conditions. Adult females of populations of Aedes aegypti from the city of Recife (P1), the city of Campinas (P2) and the Rockefeller strain from the Centers for Disease Control (P3) and one population of Aedes albopictus from Recife (P4) were fed for two hours with infected dog blood containing 2,000 microfilariae/ml of D. immitis. After artificial feeding, the specimens were maintained under controlled conditions. Ten females from each population were dissected daily over 14 days. The infection ratio and vector efficiency index were calculated and D. immitis development from L1 to L3 was assessed. The larvae in P1, P2, P3 and P4 reached the third stage in 11, 10, 14 and 9 days, respectively. The vector efficiency index was 53.8%, 20.0%, 7.4% and 25.2% in P1, P2, P3 and P4, respectively. The findings demonstrate that D. immitis larvae develop in all culicid populations studied herein. Based on mosquito mortality, development time and VEI the A. albopictus population from Recife (P4) demonstrated the best performance as vector. This is the second report of D. immitis development in A. albopictus from Brazil. The present data reinforce the role of this species as vector of D. immitis in an area where greater importance has long been given to A. aegypti.
Commitment and Oblivious Transfer in the Bounded Storage Model with Errors
Rafael Dowsley,Felipe Lacerda,Anderson C. A. Nascimento
Computer Science , 2015,
Abstract: In the bounded storage model the memory of the adversary is restricted, instead of its computational power. With this different restriction it is possible to design protocols with information-theoretical (instead of only computational) security. We present the first protocols for commitment and oblivious transfer in the bounded storage model with errors, i.e., the model where the public random sources available to the two parties are not exactly the same, but instead are only required to have a small Hamming distance between themselves. Commitment and oblivious transfer protocols were known previously only for the error-free variant of the bounded storage model, which is harder to realize.
A Fault Analytic Method against HB+
Jose Carrijo,Rafael Tonicelli,Anderson C. A. Nascimento
Computer Science , 2010, DOI: 10.1587/transfun.E94.A.855
Abstract: The search for lightweight authentication protocols suitable for low-cost RFID tags constitutes an active and challenging research area. In this context, a family of protocols based on the LPN problem has been proposed: the so-called HB-family. Despite the rich literature regarding the cryptanalysis of these protocols, there are no published results about the impact of fault analysis over them. The purpose of this paper is to fill this gap by presenting a fault analytic method against a prominent member of the HB-family: HB+ protocol. We demonstrate that the fault analysis model can lead to a flexible and effective attack against HB-like protocols, posing a serious threat over them.
Evaluation of Different Parasitological Techniques for Diagnosing Intestinal Parasites in Dogs  [PDF]
Breno Barros de Santana, Tallys Leandro Barbosa da Silva, Rafael Antonio Nascimento Ramos, Leucio Camara Alves, Gílcia Aparecida de Carvalho
Open Journal of Veterinary Medicine (OJVM) , 2015, DOI: 10.4236/ojvm.2015.52003
Abstract: Intestinal nematodes are among the most common parasites of dogs, being Toxocara spp. and Ancylostoma spp. threats to public health due to their zoonotic potential. In this study, three parasitological diagnostic techniques for detecting the eggs/oocysts of canine intestinal parasites were evaluated. Fecal samples (n = 285) were collected from the environment (i.e. public streets, squares and homes) in Garanhuns, Pernambuco, Brazil. Samples were analyzed using the Willis-Mollay simple flotation technique, spontaneous sedimentation (Hoffman, Pons and Janer) and modified centrifugal flotation. Among the samples analyzed, 56.49% (161/285) showed eggs and/or oocysts of intestinal parasites. In particular, 44.21% (126/285) were detected by the Willis technique, 45.14% (121/268) by centrifugal flotation and 31.57% (90/285) by the Hoffmann technique. The kappa index indicated good concordance between the centrifugal flotation and Willis techniques (κ = 0.625), whereas fair concordance was observed between Hoffmann and Willis (κ = 0.480), and between Hoffman and centrifugal flotation (κ = 0.433). In conclusion, the centrifugal flotation technique showed high sensitivity towards detecting Ancylostoma spp. and Toxocara spp. (the most common parasites in this study) and could be used in association with the Willis technique to obtain safe diagnoses within routine laboratory analysis.
Thermomechanical Behavior Modeling of a Cr-Ni-Mo-Mn-N Austenitic Stainless Steel  [PDF]
Rafael P. Ferreira, Eden S. Silva, Carmem C. F. Nascimento, Samuel F. Rodrigues, Clodualdo Aranas Jr., Valdemar S. Leal, Gedeon S. Reis
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.712062
Abstract: The analytical approach and the thermomechanical behavior of a Cr-Ni-Mo-Mn-N austenitic stainless steel were characterized based on the parameters of work hardening (h), dynamic recovery (r) and dynamic recrystallization (n, t0.5), considering constitutive equations (σ, ε) and deformation conditions expressed according to the Zener-Hollomon parameter (Z). The results indicated that the curves were affected by the deformation conditions and that the stress levels increased with Z under high work hardening rates. The σc/σp ratio was relatively high in the first part of the curves, indicating that softening was promoted by intense dynamic recovery (DRV). This was corroborated by the high values of r and average stacking fault energy, γsfe = 66.86 mJ/m2, which facilitated the thermally activated mechanisms, increasing the effectiveness of DRV and delaying the onset of dynamic recrystallization (DRX). The second part of the curves indicates that there was a delay in the kinetics of dynamic softening, with a higher value of t0.5 and lower values of the Avrami exponent (n) due to the competing DRV-DRX mechanisms, and steady state stress (σss) was achieved under higher rates of deformation.
Consumo nocivo de bebidas alcoólicas entre usuários de uma Unidade de Saúde da Família
Abreu, ?ngela Maria Mendes;Jomar, Rafael Tavares;Souza, Maria Helena Nascimento;Guimar?es, Raphael Mendon?a;
Acta Paulista de Enfermagem , 2012, DOI: 10.1590/S0103-21002012000200021
Abstract: objectives: to identify harmful alcohol consumption among users of a family health unit, analyzing its association with sociodemographic characteristics. methods: a cross-sectional study conducted with 1,115 subjects who responded to the alcohol use disorders identification test and questions referring to sociodemographic variables. data were submitted to tests of association, using the statistical package for the social sciences. results: an elevated prevalence was observed of harmful alcohol consumption (31.0%), strongly associated with male gender, low education level and family income. conclusion: we observed a high prevalence of harmful alcohol consumption strongly associated with male patients, with lower education and income up to two times the minimum wage.
Thermal performance and concentration of gases in facilities for pigs in semiarid region from State of Paraiba - Brazil
Furtado, Dermeval A.;Amancio, Daniele;Nascimento, José W. B. do;Gomes, Josivanda P.;Silva, Rafael C.;
Engenharia Agrícola , 2012, DOI: 10.1590/S0100-69162012000100004
Abstract: the study was conducted in a facility for pigs during the nursery and finishing in the town of 'montadas', in the semiarid of the state of paraiba, brazil, in the rainy and dry season, aiming to evaluate the concentration of oxygen, methane, carbon monoxide and ammonia, and the bioclimatic indexes: ambient temperature (at), relative humidity (rh) and the index of black globe temperature and humidity (ibgth). these indexes differed significantly (p>0.05) between the periods and times. the at in the rainy season was in the thermal comfort zone(tcz) in most of the times in the nursery; for the finishing phase, thermal discomfort occurred; during the dry season, there was thermal comfort in the nursery phase; in the finishing phase the thermal discomfort occurred at all times. in the rainy season, the ibgth was in tcz; in the dry season, it was above the tcz. the rh in the rainy period was in the tcz; in the dry season, in most of the times, below the range of the tcz. the concentration of gases showed no differences (p > 0.05) between periods and between the times, and the carbon monoxide, hydrogen sulfide and methane were below 1.0 ppm, and the ammonia showed a mean of 5.2 ppm. none of the analyzed gases exceeded the limits established by brazilian and international standards for animals and workers.
EPR and magnetic studies of a carboxylate-bridged dinuclear copper(II) compound: [cu2(flu)4(dmf)2]
Nascimento, Otaciro R.;Napolitano, Lia M. B.;Torre, María H.;Pe?a, Octavio;Calvo, Rafael;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000400009
Abstract: we report magnetic and epr (electron paramagnetic resonance) spectroscopy studies of [cu2(flu)4(dmf)2] (flu = flufenamate and dmf = dimethylformamide), which has cuii ions in tetracarboxylate "paddle wheel" dinuclear units. susceptibility measurements at 10 < t < 275 k allowed the evaluation of an antiferromagnetic intradinuclear exchange coupling j0 = -294 ± 5 cm-1 between cuii ions (hex = "j0 s1·s2). epr experiments at 300 k in powder and single-crystals at 9.5 and 34.4 ghz indicated g// = 2.373, g⊥ = 2.073 and zero field splitting parameters d = (-0.334 ± 0.001) cm"1 and e ca. 0. epr signal intensity measurements at x-band in the range 4 < t < 295 k indicated that j0 = "283 ± 5 cm"1. a higher limit |j′| < 5×10-3 cm-1 for the interdinuclear exchange coupling between neighbor units at ca.14.24 ? was estimated from the angular variation of the single crystal spectra around the magic angles. the results are discussed in terms of the structure of the dinuclear unit and the bridges connecting cuii ions and compared with values reported for similar compounds.
The tadpole of Hypsiboas atlanticus (Anura, Hylidae) from northeastern Brazil
Nascimento, Filipe A. C. do;Lima, Marcelo G. de;Skuk, Gabriel O;Sá, Rafael O. de;
Iheringia. Série Zoologia , 2009, DOI: 10.1590/S0073-47212009000400014
Abstract: the tadpole of hypsiboas atlanticus (caramaschi & velosa, 1996) is described from the municipality of maceió, state of alagoas, brazil. at stage 36 the larvae have an overall elliptical body in lateral and dorsal views, oral disc anteroventral, spiracular tube sinistral, and labial tooth row formula 2(1,2)/3(1). the oral disc is surrounded, almost completely (anterior medial gap present) by a single row of marginal papillae. described tadpoles of the h. punctatus species group can be differentiated by a combined disc oral features. additional descriptions of h. punctatus (schneider, 1799) tadpoles from populations throughout south america may be helpful in determining the status of these populations.
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