The impact of mobility on Mobile Ad Hoc Networks through the perspective of complex networks

Mobile Ad Hoc Networks (MANETs) are wireless networks where nodes’ exchange of messages does not rely on any previously deployed infrastructure. Portable devices that are capable of wireless communication have become extremely popular making possible the establishment of wide ubiquitous networks. Users connected to such networks can access the provided services anywhere and anytime. Nevertheless, this architecture suffers from a highly unstable topology since links between nodes break constantly due to users’ movement. Mobility has a paramount influence on the network topology. Therefore, it is of utmost importance to understand the impact of mobility in MANETs. In this work, we perform a thorough analysis on how mobility shape the behavior of MANETs. Our range of observation varies from general MANETs composed of walking users to a next generation of MANETs formed by vehicles moving either in a city environment or in a highway scenario, namely Vehicular Ad Hoc Networks (VANETs). Our analyses are performed observing the networks through the perspective of complex networks. We were able to identify underlying characteristics of these networks and showed how these observations can be used to improve the performance of MANETs

Adaptive security protocol selection for mobile computing

The mobile computing paradigm has introduced new problems for application developers. Challenges include heterogeneity of hardware, software, and communication protocols, variability of resource limitations and varying wireless channel quality. In this scenario, security becomes a major concern for mobile users and applications. Security requirements for each application are different, as well as the hardware capabilities of each device. To make things worse, wireless medium conditions may change dramatically with time, incurring great impact on performance and QoS guarantees for the application. Currently, most of the security solutions for mobile devices use a static set of algorithms and protocols for services such as cryptography and hashes. In this work we propose a security service, which works as a middleware, with the ability to dynamically change the security protocols used between two peers. These changes can occur based on variations on wireless medium parameters and system resource usage, available hardware resources, application-defined QoS metrics, and desired data "security levels". We compare our solution to some widespread static security protocols, demonstrate how our middleware is able to adapt itself over different conditions of medium and system, and how it can provide a performance gain in the execution of cryptographic primitives, through the use of data semantics. Keywords: Mobile computing; Autonomous computing; Adaptive computing; Security; Data semantics

AVALIAÇÃO NUTRICIONAL DE ESTUDANTES UNIVERSITÁRIOS DO SEXO FEMININO

A auto-avaliação do estado nutritional, utilizada corno estratégia de ensino no Curso de Graduação em Enfermagem, subsidiou o presente trabalho. Com esse fim, as 50 alunas do 3º semestre (idade média de 21,7 anos) registraram seu consumo de alimentos por três dias consecutivos e suas medidas de peso e altura. A análise da adequação do consumo mostrou que 98% das alunas apresentaram ingestão insuficiente (abaixo de 90% do recomendado pela National Research Council - 1980) em pelo menos um dos nutrientes analisados (proteína, cálcio, ferro e vitaminas A, B1, B2, C e niacina). Constatou-se ingestão inadequada de cálcio em 80% das alunas, de vitamina A em 72%, de ferro em 64%, de vitamina B1 e B2 em 74 e 56% respectivamente e de vitamina C em 34%. A freqüência e a gravidade da inadequação foi maior para cálcio, vitamina A e ferro: 42, 20 e 16% das alunas consumiram menos que 60% da recomendação, evidenciando uma dieta deficiente em vitaminas e minerais.The self-evaluation of nutritional status, utilized as a teaching strategy of introductory nutrition course at Nursing School (São Paulo's University), gave a subsidy to this work. With this purpose, 50 female university students 3rd'semester (mean age was 21,7) were required to complete a three days food record and report their approximate heigth and weigth. The analysis of food intake adequacy indicated that 98% of the students had insufficient intake (less than 90% of recommended of National Research Council - 1980) of, at least, one of the nutrients (protein, calcium, iron, vitamin A, B1, B2, C and niacin). It was evidenced an inadequate intake (less than 90% of RDA) of calcium (80% of the students), vitamin A (72%), iron (64%), vitamin B1 (74%), vitamin B2 (56%) and vitamin C (34%). The inadequate intake was more frequently and serious (less than 60% RDA) for calcium (42%), vitamin A (20%) and iron (16%) showing a vitamins and minerals deficient diet

Análise não-paramétrica da sanidade de sementes e índices de eliminação e classificação de genótipos de soja Non-parametric analysis of seed sanity and elimination and ranking indices of soybean genotypes

O objetivo deste trabalho foi avaliar genótipos de soja quanto à sanidade de semente, com um método de análise, pelo qual se obtém índices de sanidade (eliminação e classificação) com base em análise não-paramétrica. Esses índices consistiram em eliminar os genótipos com incidência de patógenos acima de um dado valor, estabelecido pelo experimentador e, em seguida, classificar os genótipos não eliminados, por ordem de incidência desses patógenos. A fim de comprovar sua eficácia, realizaram-se a simulação e comparação desse método com outros, e seu uso em dados de germinação e sanidade das sementes de cultivares e linhagens de soja, de ensaios finais do Programa de Melhoramento de Soja, do Departamento de Fitotecnia, da Universidade Federal de Viçosa, conduzidos no ano agrícola de 2002/2003. Os pesos das variáveis e os limites de corte, utilizados nos índices, foram estabelecidos tendo-se levado em consideração estudos que relacionam a sanidade das sementes e sua germinação. A utilização dos índices propostos permite classificar genótipos de soja, quanto à qualidade sanitária das sementes, e eliminar das análises os genótipos que não atingiram os níveis mínimos requeridos.<br>The objective of this work was to assess soybean genotypes for seed sanity, with a method by which a sanity index (elimination and classification) is obtained based on non-parametric analysis. This index consisted in the elimination of genotypes with pathogen incidence above a certain value, established by the researcher, and then the classification of the noneliminated genotypes in the first step, ordering them according to the incidence of the pathogens. To verify its effectiveness, it was accomplished a simulation study and comparison of this proposed method with others, and its use in germination and sanity data of seeds from soybean lineages and cultivars of final experiments of the Soybean Breeding Program of Departmento de Fitotecnia, Universidade Federal de Viçosa, in 2002/2003 crop season. The weights of the variables and the cut limits used in the index were established considering studies related to seeds sanity and their germinations. The use of the proposed index allows the ranking of soybean genotypes, regarding to the sanitary quality of the seeds, and the elimination from the analyses of the genotypes that have not reached the requested minimum levels

Molecular characterization of hairy fleabane using RAPD.

ABSTRACT With the increase of glyphosate resistance evolution in hairy fleabane, the knowledge of genetic diversity is essential to assist in the weed management. The objective was to characterize the genetic diversity of glyphosate resistant Conyza species in Rio Grande do Sul. Hairy fleabane biotype seeds were collected in fields of glyphosate-resistant soybean, generating seedlings used for extracting DNA from the leaves to perform a genetic diversity analysis, using the RAPD technique. The DNA was used in polymerase chain reaction and DNA fragments were assessed for polymorphism bands in electrophoresis. Biotypes were identified as Conyza bonariensis and microcephala varieties. In molecular analysis, among 25 primers RAPD, eight were reproducible generating polymorphisms of high intensity for the separation of biotypes. Cluster analysis revealed five groups, which had a genetic similarity of 53%. The results indicate that all known biotypes are of the same species, but exhibit different varieties. RAPD presents itself as an important tool for characterizing Conyza species

Consumo, digestibilidade e desempenho de novilhas alimentadas com casca de café em substituição à silagem de milho Intake, digestibility and performance of dairy heifers fed coffee hulls replacing of corn silage

Objetivou-se avaliar a substituição da silagem de milho pela casca de café em dietas de novilhas leiteiras sobre os consumos, as digestibilidades aparentes totais dos nutrientes e o desempenho dos animais. Foram utilizadas 24 novilhas holandesas, puras e mestiças, distribuídas, de acordo com o peso inicial dos animais, em delineamento em blocos casualizados com quatro tratamentos (níveis de casca de café: 0,0; 7,0; 14,0 e 21,0% na base da MS total) e seis repetições. Diariamente, todas as novilhas foram alimentadas com 2 kg de concentrado. Os consumos de MS aumentaram linearmente, enquanto os consumos de matéria natural (MN) não foram influenciados pela inclusão de casca de café nas dietas. O aumento no consumo de MS foi de aproximadamente 20 g para cada unidade de casca de café adicionada na dieta (% MS) e o consumo médio de MN foi de 13,84 kg/dia. As digestibilidades de MS, MO, PB, CT e FDN e a concentração de NDT das dietas reduziram linearmente com a substituição da silagem de milho pela casca de café, observando-se redução de 0,158 unidades percentuais na digestibilidade da MS para cada unidade de casca de café adicionada na dieta (% MS). A inclusão de casca de café afetou de modo negativo o ganho de peso, que reduziu linearmente (5,51 g de PV por unidade de casca de café adicionada a dieta) conforme aumentaram os níveis de casca de café em substituição a silagem de milho. Em dietas para novilhas leiteiras, a casca de café pode substituir a silagem de milho em níveis de até 14% na MS total.<br>The objective was to evaluate the replacement corn silage by coffee hulls in the diet on performance, total apparent digestibility of dairy heifers. Twenty-four dairy Holstein heifers, purebred and crossbred, were assigned, according to animal initial weight, to a randomized block design with four treatments (Coffee hulls levels: 0.0, 7.0, 14.0, and 21.0% DM basis) and six replicates. All heifers were daily fed 2.0 kg concentrate. DM intake linearly increased, while fresh matter (FM) intake was not affected by the inclusion of coffee hulls in the diets. The increment of DM intake was approximately 20 g per unit of coffee hulls added to the diet (% DM) and the average intake of FM was 13.84 kg/d. Digestibilities of DM, OM, CP, CHO, NDF and the concentration of NDT in the diet linearly decreased with the replacement of corn silage by coffee hulls, observing a reduction of 0.158 percent units in the digestibility of the DM per unit of coffee hulls added to the diet (% DM). The inclusion of coffee hulls negatively affected the weight gain that linearly decrease (5.51g BW) per unit of coffee hulls added to the diet), as the coffee hulls levels increased, in replacement of corn silage. Coffee hulls could replace corn silage up to 14% level, DM basis, in diets for dairy heifers