A Routing Protocol Based on Energy and Link Quality for Internet of Things Applications

The Internet of Things (IoT) is attracting considerable attention from the universities, industries, citizens and governments for applications, such as healthcare, environmental monitoring and smart buildings. IoT enables network connectivity between smart devices at all times, everywhere, and about everything. In this context, Wireless Sensor Networks (WSNs) play an important role in increasing the ubiquity of networks with smart devices that are low-cost and easy to deploy. However, sensor nodes are restricted in terms of energy, processing and memory. Additionally, low-power radios are very sensitive to noise, interference and multipath distortions. In this context, this article proposes a routing protocol based on Routing by Energy and Link quality (REL) for IoT applications. To increase reliability and energy-efficiency, REL selects routes on the basis of a proposed end-to-end link quality estimator mechanism, residual energy and hop count. Furthermore, REL proposes an event-driven mechanism to provide load balancing and avoid the premature energy depletion of nodes/networks. Performance evaluations were carried out using simulation and testbed experiments to show the impact and benefits of REL in small and large-scale networks. The results show that REL increases the network lifetime and services availability, as well as the quality of service of IoT applications. It also provides an even distribution of scarce network resources and reduces the packet loss rate, compared with the performance of well-known protocols.

Managing Things and Services with Semantics: A Survey

This paper presents a survey on the usage, opportunities and pitfalls of semantic technologies in the Internet of Things. The survey was conducted in the context of a semantic enterprise integration platform. In total we surveyed sixty-one individuals from industry and academia on their views and current usage of IoT technologies in general, and semantic technologies in particular. Our semantic enterprise integration platform aims for interoperability at a service level, as well as at a protocol level. Therefore, also questions regarding the use of application layer protocols, network layer protocols and management protocols were integrated into the survey. The survey suggests that there is still a lot of heterogeneity in IoT technologies, but first indications of the use of standardized protocols exist. Semantic technologies are being recognized as of potential use, mainly in the management of things and services. Nonetheless, the participants still see many obstacles which hinder the widespread use of semantic technologies: Firstly, a lack of training as traditional embedded programmers are not well aware of semantic technologies. Secondly, a lack of standardization in ontologies, which would enable interoperability and thirdly, a lack of good tooling support.

AIDS defining opportunistic infections in patients with high CD4 counts in the combination antiretroviral therapy (cART) era: things ain't what they used to be.

INTRODUCTION According to reports from observational databases, classic AIDS-defining opportunistic infections (ADOIs) occur in patients with CD4 counts above 500/µL on and off cART. Adjudication of these events is usually not performed. However, ADOIs are often used as endpoints, for example, in analyses on when to start cART. MATERIALS AND METHODS In the database, Swiss HIV Cohort Study (SHCS) database, we identified 91 cases of ADOIs that occurred from 1996 onwards in patients with the nearest CD4 count >500/µL. Cases of tuberculosis and recurrent bacterial pneumonia were excluded as they also occur in non-immunocompromised patients. Chart review was performed in 82 cases, and in 50 cases we identified CD4 counts within six months before until one month after ADOI and had chart review material to allow an in-depth review. In these 50 cases, we assessed whether (1) the ADOI fulfilled the SHCS diagnostic criteria (www.shcs.ch), and (2) HIV infection with CD4 >500/µL was the main immune-compromising condition to cause the ADOI. Adjudication of cases was done by two experienced clinicians who had to agree on the interpretation. RESULTS More than 13,000 participants were followed in SHCS in the period of interest. Twenty-four (48%) of the chart-reviewed 50 patients with ADOI and CD4 >500/µL had an HIV RNA <400 copies/mL at the time of ADOI. In the 50 cases, candida oesophagitis was the most frequent ADOI in 30 patients (60%) followed by pneumocystis pneumonia and chronic ulcerative HSV disease (Table 1). Overall chronic HIV infection with a CD4 count >500/µL was the likely explanation for the ADOI in only seven cases (14%). Other reasons (Table 1) were ADOIs occurring during primary HIV infection in 5 (10%) cases, unmasking IRIS in 1 (2%) case, chronic HIV infection with CD4 counts <500/µL near the ADOI in 13 (26%) cases, diagnosis not according to SHCS diagnostic criteria in 7 (14%) cases and most importantly other additional immune-compromising conditions such as immunosuppressive drugs in 14 (34%). CONCLUSIONS In patients with CD4 counts >500/ µL, chronic HIV infection is the cause of ADOIs in only a minority of cases. Other immuno-compromising conditions are more likely explanations in one-third of the patients, especially in cases of candida oesophagitis. ADOIs in HIV patients with high CD4 counts should be used as endpoints only with much caution in studies based on observational databases.