This paper addresses the problem of finding an analytical expression for the end-to-end Average Bit Error Rate (ABER) in multihop Decode-and-Forward (DAF) routes within the context of wireless networks. We provide an analytical recursive expression for the most generic case of any number of hops and any single-hop ABER for every hop in the route. Then, we solve the recursive relationship in two scenarios to obtain simple expressions for the end-to-end ABER, namely: (a) The simplest case, where all the relay channels have identical statistical behaviour; (b) The most general case, where every relay channel has a different statistical behaviour. Along with the theoretical proofs, we test our results against simulations. We then use the previous results to obtain closed analytical expressions for the end-to-end ABER considering DAF relays over Nakagami-fading channels and with various modulation schemes. We compare these results with the corresponding expressions for Amplify-and-Forward (AAF) and, after corroborating the theoretical results with simulations, we conclude that DAF strategy is more advantageous than the AAF over Nakagami-fading channels as both the number of relays and-index increase. Index Terms-Bit error rate, end-to-end performance, decode and forward, amplify and forward, fading channel, multihop wireless networks. Eduardo Morgado received a degree in telecommunication engineering from the University Carlos III de Madrid, Spain, in 2004 and the PhD degree from the University Rey Juan Carlos, Spain, in 2009. Currently, he is an associate professor in the

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A systematic review of telemedicine projects in Colombia was conducted. We searched electronic databases, and also searched for relevant Internet websites. Each project manager was contacted by telephone to identify projects which had not actually been carried out. They were interviewed to request information about the projects they were managing, and whether they knew of other projects in Colombia. The search process identified 43 different projects, which were classified into two groups: telemedicine research initiatives and projects for providing health-care services via telemedicine. There were 32 projects which provided telemedicine services, of which 14 had been finished, 11 remained active, 4 were being implemented and no data were available about the state of the other 3. Health-care services had been provided using telemedicine to at least 550,000 patients. The projects had connected more than 650 health-care institutions, mainly in deprived areas of the country. Unfortunately, although many projects seem to have had a positive effect, none of them had been rigorously evaluated, and therefore in the absence of scientific evidence no general recommendations can be made. However, the methodology of the present study appears suitable for similar reviews of telemedicine in other developing countries.

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Wireless Sensor Networks are composed of low cost and extremely power constrained sensor nodes scattered over a spatial region. They form multi-hop and self organized networks, making energy consumption a crucial design issue. Research has shown that clustering sensor nodes is an efficient method to manage energy consumption for prolonging the network lifetime, but most of routing protocols focus on homogeneous sensor networks and they are not optimized for the characteristics of heterogeneous networks, in which a percentage of the sensor nodes is equipped with additional energy capacities. In this paper we evaluate the performance of a new scalable architecture HARP, Hierarchical Adaptive and Reliable Routing Protocol, in a heterogeneous scenario. HARP provides efficient link fault tolerance and also supports node mobility management. Furthermore, a new cluster head election formulation protocol (s-HARP) has been adapted to heterogeneous networks. Our performance evaluation has shown that HARP and s-HARP can significantly reduce the energy consumption and prolong the useful lifetime of the network outperforming some popular existing clustering protocols.

Spectral analysis is widely applied to bioelectric cardiac signals for quantifying the spatiotemporal organization of cardiac tissue. Nevertheless, to date it is not well understood how lead characteristics affect the spectrum of recorded cardiac signals and, as a consequence, the interpretation of cardiac spectrum is still controversial. In this paper we use simulation methods to investigate the effects of lead spatial resolution on the spectrum of cardiac signals. We simulate three cardiac rhythms of different degrees of spatiotemporal organization in a square sample of cardiac tissue. Then, by using a lead field approach, we synthesize the signals recorded by four idealized leads of different spatial resolution. Finally, we estimate the spectrum of simulated cardiac signals. Our simulations indicate that lead spatial resolution affects cardiac spectrum, although the effects depend on the organization of the underlying rhythm. Specifically, our simulations show that for highly organized rhythms, the smaller the lead resolution region, the broader the distribution of power in frequency. Since lead resolution can affect significantly cardiac spectrum, we conclude that caution should be used when quantifying cardiac spatiotemporal organization based on the spectrum of cardiac signals.

The process of routing in large ad-hoc mobile networks is theoretically analyzed as the capacity of a packet to be directed form a source to a destination. The equivalence between directivity and an effective radius, which represents the actual knowledge of any node of its neighbourhood, is demonstrated. The mobility of the network is modelled as that resulting from the most probable distribution of mobile nodes. The results are conclusive: mobility reduces the throughput and delay performance of any routing algorithm with a finite effective radius.

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