Adaptive self-management of teams of autonomous vehicles

Unmanned Autonomous Vehicles (UAVs) are increasingly deployed for missions that are deemed dangerous or impractical to perform by humans in many military and disaster scenarios. Collaborating UAVs in a team form a Self- Managed Cell (SMC) with at least one commander. UAVs in an SMC may need to operate independently or in sub- groups, out of contact with the commander and the rest of the team in order to perform specific tasks, but must still be able to eventually synchronise state information. The SMC must also cope with intermittent and permanent communication failures as well permanent UAV failures. This paper describes a failure management scheme that copes with both communication link and UAV failures, which may result in temporary disjoint sub-networks within the SMC. A communication management protocol is proposed to control UAVs performing disconnected individual operations, while maintaining the SMCs structure by trying to ensure that all members of the mission regardless of destination or task, can communicate by moving UAVs to act as relays or by allowing the UAVs to rendezvous at intermittent intervals. Copyright 2008 ACM.Accepted versio

A Mission Management Framework for Unmanned Autonomous Vehicles

Accepted versio

Secure dynamic community establishment in coalitions

Accepted versio

Study on the epidemiology of foot and mouth disease in Ethiopia

Summary This study was designed to describe the status of foot and mouth disease (FMD) in Ethiopia, through analysis of FMD outbreak reports and the detection of antibodies, to address the possibility of establishing a disease-free zone. The serum samples were tested using the 3ABC enzyme-linked immunosorbent assay kit, to identify antibodies against FMD. From a total of 4,465 sera, 10.5% (n = 467) tested positive. The highest seroprevalence was detected in samples from the Eastern zone of Tigray with 41.5%; followed by the Guji zone of Oromia and Yeka district of the city of Addis Ababa, with 32.7% and 30%, respectively. Antibodies specific to FMD virus were not detected in Gambella or Benishangul. The effects of cattle, sheep and goat density, both separately and together, were analysed with a spatial regression model, but did not have a significant effect on seroprevalence. This indicates that other factors, such as farming systems and livestock movement, play a significant role in the occurrence of FMD. Based on these study findings, it might be appropriate to establish disease-free zones in Gambella and Benishangul

Cryptosporidium in Calves, Lambs and Kids at Haramaya, eastern Ethiopia

A cross sectional study was carried out from November 2010 to April 2011 to determine the prevalence of Cryptosporidium in calves, lambs and kids and to assess potential risk factors in Haramaya, eastern Ethiopia. Hence, fecal samples from a total of 237 study animals (133 calves, 63 lambs and 41 kids) were tested with Sheather’s flotation technique and Modified Ziehl-Neelsen Staining. Accordingly, the overall prevalence was found to be 23.6% (56/237) with the prevalence of 27.8% (37/133) in calves, 22.2% (14/63) in lambs and 12.2% (5/41) in kids. The prevalence of Cryptosporidium significantly (p = 0.047) varied with species of study animals being three times higher likelihood of occurrence in calves compared to its chance of occurrence in kids (OR = 2.8, 95%CI = 1.0, 7.6). No significant difference in prevalence was observed between kids and lambs. The occurrence of the disease was also assessed among the species of animals by taking into consideration different demographic characteristic of the animals including breed, age and sex. For caprine, the prevalence was higher in the cross breed animals (28.6%) followed by the breed of Hararge highland (25%) with no report of the disease in Boer and Ogaden breeds. In ovine, no association was observed between the infection occurrence and the potential risk factors. Analysis of the risk factors in bovine revealed a significant (p = 0.044) difference in disease occurrence among age groups with almost three times more likelihood of the disease occurrence in calves under 3 months than older age category(OR = 2.9, 95%CI = 1.0, 8.2). In conclusion, this study demonstrated the importance of Cryptosporidium in young ruminants with a higher prevalence among calves than lambs and kids.Key words: Cryptosporidium; Prevalence; Risk Factors; Calves, Lambs, Kids, Haramaya, Ethiopi

The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa.

BACKGROUND: Onchocerciasis transmission across international borders is not uncommon, yet a coordinated cross border stops mass drug administration (MDA) decision has not been documented. METHODS/PRINCIPLE FINDINGS: The Galabat-Metema focus involves neighboring districts on the border between Sudan and Ethiopia. Mass drug administration (MDA) was provided once and subsequently twice per year in this focus, with twice-per-year beginning in Ethiopia's Metema subfocus in 2016 and in the Sudan's Galabat subfocus in 2008. Ov16 ELISA-based serosurveys were conducted in 6072 children under 10 years of age in the Metema subfocus in 2014, and 3931 in the Galabat in 2015. Between 2014 and 2016, a total of 27,583 vector Simulium damnosum flies from Metema and 9,148 flies from Galabat were tested by pool screen PCR for Onchocerca volvulus O-150 DNA. Only 8 children were Ov16 seropositive (all in the Metema subfocus); all were negative by skin snip PCR. The upper limit of the 95% confidence interval (UCL) for Ov16 seropositive was <0.1% for the overall focus and 0.14 positive fly heads per 2000 (UCL = 0.39/2000). However, an entomological 'hotspot' was detected on the Wudi Gemzu river in Metema district. The hotspot was confirmed when 4 more positive fly pools were found on repeat testing in 2017 (1.04 L3/2000 flies (UCL = 2.26/2000). Information exchange between the two countries led to stopping MDA in a coordinated fashion in 2018, with the exception of the hotspot at Wudi Gemzu, where MDA with ivermectin was increased to every three months to hasten interruption of transmission. CONCLUSION: Coordinated stop MDA decisions were made by Sudan and Ethiopia based on data satisfying the World Health Organization's criteria for interruption of onchocerciasis transmission. Definitions of entomological 'hotspots' and buffer zones around the focus are proposed

The role of grass volatiles on oviposition site selection by Anopheles arabiensis and Anopheles coluzzii

Background: The reproductive success and population dynamics, of Anopheles malaria mosquitoes is strongly influenced by the oviposition site selection of gravid females. Mosquitoes select oviposition sites at different spatial scales, starting with selecting a habitat in which to search. This study utilizes the association of larval abundance in the field with natural breeding habitats, dominated by various types of wild grasses, as a proxy for oviposition site selection by gravid mosquitoes. Moreover, the role of olfactory cues emanating from these habitats in the attraction and oviposition stimulation of females was analysed. Methods: The density of Anopheles larvae in breeding sites associated with Echinochloa pyramidalis, Echinochloa stagnina, Typha latifolia and Cyperus papyrus, was sampled and the larvae identified to species level. Headspace volatile extracts of the grasses were collected and used to assess behavioural attraction and oviposition stimulation of gravid Anopheles arabiensis and Anopheles coluzzii mosquitoes in wind tunnel and two-choice oviposition assays, respectively. The ability of the mosquitoes to differentiate among the grass volatile extracts was tested in multi-choice tent assays. Results: Anopheles arabiensis larvae were the most abundant species found in the various grass-associated habitats. The larval densities described a hierarchical distribution, with Poaceae (Echinochloa pyramidalis and Echinochloa stagnina)-associated habitat sites demonstrating higher densities than that of Typha-associated sites, and where larvae were absent from Cyperus-associated sites. This hierarchy was maintained by gravid An. arabiensis and An. coluzzii mosquitoes in attraction, oviposition and multi-choice assays to grass volatile extracts. Conclusions: The demonstrated hierarchical preference of gravid An. coluzzii and An. arabiensis for grass volatiles indicates that vegetation cues associated with larval habitats are instrumental in the oviposition site choice of the malaria mosquitoes. Identifying volatile cues from grasses that modulate gravid malaria mosquito behaviours has distinct potential for the development of tools to be used in future monitoring and control methods