Hybrid Flooding Scheme for Mobile Ad Hoc Networks

A hybrid broadcast scheme for mobile wireless networks is proposed in this letter. The main objective is to combine different flooding schemes in order to solve the broadcast storm issue encountered by the simple flooding scheme. For this purpose, the density of nodes is taken into account using a density metric called expansion metric. In addition, in order to reduce the broken links due to mobility of nodes and increasing dissimilarity among the intermediate nodes, a forwarding zone criterion is included in the proposed schemes. The proposed approaches have been implemented and compared with pure probabilistic flooding, and simple flooding schemes

Study of impact on helicopter blade

This article presents a study of damage in structures that are similar to helicopter blade sections, subjected to an impact. These complex composite structures were impacted by a steel ball of 125 g at impact speed ranging from 30 to 130 m/s. This led to properly highlight the kinematics of the impact and to define the sequence of the damage’s mechanisms. An explicit FE model is also presented. The damage modelling of the roving is performed through a scale change. It allows a good representation of observed experimental behaviour. As the mesh density is low, it can be used for the modelling of a real structure

Multiple primary tumours: incidence estimation in the presence of competing risks

<p>Abstract</p> <p>Background</p> <p>Estimating the risk of developing subsequent primary tumours in a population is difficult since the occurrence probability is conditioned to the survival probability.</p> <p>Methods</p> <p>We proposed to apply Markov models studying the transition intensities from first to second tumour with the Aalen-Johansen (AJ) estimators, as usually done in competing risk models. In a simulation study we applied the proposed method in different settings with constant or varying underlying intensities and applying age standardisation. In addition, we illustrated the method with data on breast cancer from the Piedmont Cancer Registry.</p> <p>Results</p> <p>The simulation study showed that the person-years approach led to a sensibly wider bias than the AJ estimators. The largest bias was observed assuming constantly increasing incidence rates. However, this situation is rather uncommon dealing with subsequent tumours incidence. In 9233 cases with breast cancer occurred in women resident in Turin, Italy, between 1985 and 1998 we observed a significant increased risk of 1.91 for subsequent cancer of corpus uteri, estimated with the age-standardised Aalen-Johansen incidence ratio (AJ-IR^stand), and a significant increased risk of 1.29 for cancer possibly related to the radiotherapy of breast cancer. The peak of occurrence of those cancers was observed after 8 years of follow-up.</p> <p>Conclusion</p> <p>The increased risk of a cancer of the corpus uteri, also observed in other studies, is usually interpreted as the common shared risk factors such as low parity, early menarche and late onset of menopause. We also grouped together those cancers possibly associated to a previous local radiotherapy: the cumulative risk at 14 years is still not significant, however the AJ estimators showed a significant risk peak between the eighth and the ninth year. Finally, the proposed approach has been shown to be reliable and informative under several aspects. It allowed for a correct estimation of the risk, and for investigating the time trend of the subsequent cancer occurrence.</p

Uma Geração Sem Terra: Injustiça Ambiental em Comunidades Indígenas Deslocadas por Construções de Hidrelétricas no Brasil, desde os Anos 1980

O Brasil tem uma dívida antiga com comunidades indígenas deslocadas em decorrência da construção de hidrelétricas, que fornecem energia para as cidades, fábricas e terras agrícolas do país. Um caso importante é a comunidade atingida pela Hidrelétrica de Itaparica, construída entre as décadas de 1970 e 1980, no trecho submédio do rio São Francisco, no Nordeste semiárido. O reservatório deslocou, além de dezenas de milhares de lavradores, os Tuxá, um povo indígena que vivia há séculos na área alagada pela usina. Para os Tuxá, esse deslocamento tem sido particularmente danoso, porque, desde os anos 1980, o governo tem renegado a promessa de garantir uma terra compensatória para o grupo. O bem-estar material e a identidade cultural dos Tuxá estão enraizados na sua terra, mas o grupo já está há mais de três décadas sem terra, o que representa um período de mais de uma geração humana. Este artigo conta a história do deslocamento do povo Tuxá e sua luta pela terra, no esforço de dar visibilidade a este caso ainda não resolvido de injustiça socioambiental