334 research outputs found
A High Reliability Asymptotic Approach for Packet Inter-Delivery Time Optimization in Cyber-Physical Systems
In cyber-physical systems such as automobiles, measurement data from sensor
nodes should be delivered to other consumer nodes such as actuators in a
regular fashion. But, in practical systems over unreliable media such as
wireless, it is a significant challenge to guarantee small enough
inter-delivery times for different clients with heterogeneous channel
conditions and inter-delivery requirements. In this paper, we design scheduling
policies aiming at satisfying the inter-delivery requirements of such clients.
We formulate the problem as a risk-sensitive Markov Decision Process (MDP).
Although the resulting problem involves an infinite state space, we first prove
that there is an equivalent MDP involving only a finite number of states. Then
we prove the existence of a stationary optimal policy and establish an
algorithm to compute it in a finite number of steps.
However, the bane of this and many similar problems is the resulting
complexity, and, in an attempt to make fundamental progress, we further propose
a new high reliability asymptotic approach. In essence, this approach considers
the scenario when the channel failure probabilities for different clients are
of the same order, and asymptotically approach zero. We thus proceed to
determine the asymptotically optimal policy: in a two-client scenario, we show
that the asymptotically optimal policy is a "modified least time-to-go" policy,
which is intuitively appealing and easily implementable; in the general
multi-client scenario, we are led to an SN policy, and we develop an algorithm
of low computational complexity to obtain it. Simulation results show that the
resulting policies perform well even in the pre-asymptotic regime with moderate
failure probabilities
Using Community-Owned Resource Persons to Provide Early Diagnosis and Treatment and Estimate Malaria Burden at Community Level in North-Eastern Tanzania.
Although early diagnosis and prompt treatment is an important strategy for control of malaria, using fever to initiate presumptive treatment with expensive artemisinin combination therapy is a major challenge; particularly in areas with declining burden of malaria. This study was conducted using community-owned resource persons (CORPs) to provide early diagnosis and treatment of malaria, and collect data for estimation of malaria burden in four villages of Korogwe district, north-eastern Tanzania.In 2006, individuals with history of fever within 24 hours or fever (axillary temperature ≥37.5°C) at presentation were presumptively treated using sulphadoxine/pyrimethamine. Between 2007 and 2010, individuals aged five years and above, with positive rapid diagnostic tests (RDTs) were treated with artemether/lumefantrine (AL) while under-fives were treated irrespective of RDT results. Reduction in anti-malarial consumption was determined by comparing the number of cases that would have been presumptively treated and those that were actually treated based on RDTs results. Trends of malaria incidence and slide positivity rates were compared between lowlands and highlands. Of 15,729 cases attended, slide positivity rate was 20.4% and declined by >72.0% from 2008, reaching <10.0% from 2009 onwards; and the slide positivity rates were similar in lowlands and highlands from 2009 onwards. Cases with fever at presentation declined slightly, but remained at >40.0% in under-fives and >20.0% among individuals aged five years and above. With use of RDTs, cases treated with AL decreased from <58.0% in 2007 to <11.0% in 2010 and the numbers of adult courses saved were 3,284 and 1,591 in lowlands and highlands respectively. Malaria incidence declined consistently from 2008 onwards; and the highest incidence of malaria shifted from children aged <10 years to individuals aged 10-19 years from 2009. With basic training, supervision and RDTs, CORPs successfully provided early diagnosis and treatment and reduced consumption of anti-malarials. Progressively declining malaria incidence and slide positivity rates suggest that all fever cases should be tested with RDTs before treatment. Data collected by CORPs was used to plan phase 1b MSP3 malaria vaccine trial and will be used for monitoring and evaluation of different health interventions. The current situation indicates that there is a remarkable changing pattern of malaria and these areas might be moving from control to pre-elimination levels
Letter Of Geoff Tansey To Turkish Parliament
Letter of Geoff Tansey To Turkish Parliament (En/Tr
Typing of Ralstonia solanacearum isolated from tomato by antibiotic susceptibility, plasmid profiling and PCR-based techniques of RAPD and ERIC
The epidemiological characteristics of Ralstonia solanacearum isolated from tomato plants in Sarawak and Selangor were studied. The epidemiological analysis of the strains was carried out through antibiotic resistant pattern, plasmid profiles, randomly amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus (ERIC) methods. Six strains were susceptible to all antibiotics tested, whereas the 10 strains that were resistant to one or more antibiotics were grouped into six antibiotic resistance patterns. Small single plasmid of 7.2 Mda and 9.2 Mda were detected among the nine plasmid containing strains, enabling them to be grouped into only two plasmid patterns. In the polymerase chain reaction, based methods using RAPD and ERIC, two strains were untypable by RAPD, whereas all were typable by ERIC. In this study, a wide diversity of R. solanacearum strains was examined. ERIC analysis demonstrated the clonal relationship between isolates from tomato plants in Sarawak and Selangor. The existence of similar R. solanacearum strains in tomato plants from two very distant locations should be considered if tomato strain fingerprint results were to be used to help trace the vehicles for transmission
Probabilistic seismic hazard maps for the sultanate of Oman
This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in the framework of logic tree for Oman. The earthquake catalogue was homogenized, declustered, and used to define seismotectonic source model that characterizes the seismicity of Oman. Two seismic source models were used in the current study; the first consists of 26 seismic source zones, while the second is expressing the alternative view that seismicity is uniform along the entire Makran and Zagros zones. The recurrence parameters for all the seismogenic zones were determined using the doubly bounded exponential distribution except the zones of Makran, which were modelled using the characteristic distribution. Maximum earthquakes were determined and the horizontal ground accelerations in terms of geometric mean were calculated using ground-motion prediction relationships developed based upon seismic data obtained from active tectonic environments similar to those surrounding Oman. The alternative seismotectonic source models, maximum magnitude, and ground-motion prediction relationships were weighted and used to account for the epistemic uncertainty. Hazard maps at rock sites were produced for 5 % damped spectral acceleration (SA) values at 0.1, 0.2, 0.3, 1.0 and 2.0 s spectral periods as well as peak ground acceleration (PGA) for return periods of 475 and 2,475 years. The highest hazard is found in Khasab City with maximum SA at 0.2 s spectral period reaching 243 and 397 cm/s[superscript 2] for return periods 475 and 2,475 years, respectively. The sensitivity analysis reveals that the choice of seismic source model and the ground-motion prediction equation influences the results most.Oman Ministerial Cabinet (project number 22409017
Inspección de riesgos geológicos en prevención a los efectos del fenómeno del niño en los asentamientos humanos comprendidos entre el Rio Chillón y la quebrada Jicamarca. Distritos: Carabayllo, Comas, Independencia, Rímac, San Juan de Lurigancho, provincia de Lima, departamento de Lima
El estudio de los Riesgos Geológicos está considerado dentro de los lineamientos de la política institucional del INGEMMET. Dados los indicadores meteorológicos y oceanográficos que aseguran la próxima ocurrencia e influencia del fenómeno meteorológico de "El Niño", el Gobierno ha adoptado medidas de prevención que continuamente son divulgados por los medios de Información, el INGEMMET ante su ocurrencia, considera conveniente contribuir a éste empeño del Gobierno Central, por lo cual programó una inspección de campo a cargo de especialistas en riesgos geológicos a las áreas de los Asentamientos Humanos ubicados en la periferie de la ciudad de Lima Metropolitana comprendidas entre el Río Chillón y la Quebrada de Jicamarca, con el fin de observar in-situ el estado de los Asentamientos Humanos y obras de infraestructura y los posibles efectos que ocasionarían en ellos el fenómeno de “El Niño". Como resultado de la inspección se presenta el siguiente informe en forma de cuadros y fotografías en el que se enmarcan las sugerencias que son necesarias tener en cuenta en los trabajos de prevención para minimizar o controlar sus efectos
Inspección de riesgo geológico del valle del río Aobamba. Dist. Machupicchu, prov. Urubamba, dpto. Cusco
El INDECI mediante oficio N°6022, del 30 de julio de 1996, solicita a INGEMMET. integrante del Sistema Nacional de Defensa Civil (SINADECI), del Comité Nacional del Decenio Internacional para la Reducción de los Desastres Naturales (CN-DIRDN) y del Consejo Consultivo Científico Tecnológico del Instituto Nacional de Defensa Civil (CCCT -INDECI), realice la "Evaluación de riesgo geológico del valle del río Aobamba, efectuada por una avalancha-aluvión con pérdidas de vidas humanas, personas heridas, propiedad dañada e interrupción de las actividades económicas y proponga las medidas pertinentes que ayuden a prevenir y mitigar los efectos de futuros fenómeno ocurrentes en el área, evitando que afecten la actividad comercial agrícola y turística. Con la aprobación del Consejo Directivo del INGEMMET, la Dirección de Geotecnia destacó a dos profesionales especialistas en Riesgo Geológico para que efectúen la inspección ingeniero Geológica de la Seguridad Física del valle del Río Aobamba en la Provincia de Urubamba Departamento de Cuzco. El presente informe es el resultado de los trabajos de campo realizados entre los días 16 al 18 de agosto del año en curso
Size-Tailored Physicochemical Properties of Monodisperse Polystyrene Nanoparticles and the Nanocomposites Made Thereof
The latex monodisperse polystyrene (PS) colloids are important for different advanced applications (e.g. in coating, biotechnology etc.). However, the size dependency of their structural properties that impacts the characteristics of the nanocomposites composed thereof is largely unknown. Here, monodisperse PS nanoparticles (MPNPs) are synthesized via emulsion polymerization in five sizes (50, 150, 300, 350, and 450 nm). The size of the PS MPNPs is tailored by controlling the reaction time, temperature, and amount of surfactant and initiator. The correlation between the particle size and structural properties of the PS MPNPs is established by different thermomechanical and optical characterizations. The smaller particles (50 and 150 nm) show a lower glass transition (Tg) and thermal decomposition temperature and a lower Raman peak intensity. Yet, they trigger a higher IR absorption, thanks to a larger surface area. When incorporated in a polyvinyl alcohol (PVA) matrix, the smaller particles impart the resulting nanocomposite a higher tensile strength, and elastic and storage moduli. Whereas, they decline the elongation and loss factor. The very few examples of the MPNPs incorporated polymeric nanocomposites have been unstudied from this perspective. Thus, these tangible knowledge can profit scalable production of this kind of nanocomposite materials for different applications in a cost/energy efficient manner.Peer reviewe
Joint topology optimization, power control and spectrum allocation for intra-vehicular multi-hop sensor networks using dandelion-encoded heuristics
In the last years the interest in multi-hop communications has gained momentum within the research community due to the challenging characteristics of the intra-vehicular radio environment and the stringent robustness imposed on critical sensors within the vehicle. As opposed to point-to-point network topologies, multi-hop networking allows for an enhanced communication reliability at the cost of an additional processing overhead. In this context this manuscript poses a novel bi-objective optimization problem aimed at jointly minimizing (1) the average Bit Error Rate (BER) of sensing nodes under a majority fusion rule at the central data collection unit; and (2) the mean delay experienced by packets forwarded by such nodes due to multi-hop networking, frequency channel switching time multiplexing at intermediate nodes. The formulated paradigm is shown to be computationally tractable via a combination of evolutionary meta-heuristic algorithms and Dandelion codes, the latter capable of representing tree-like structures like those modeling the multi-hop routing approach. Simulations are carried out for realistic values of intra-vehicular radio channels and co-channel interference due to nearby IEEE 802.11 signals. The obtained results are promising and pave the way towards assessing the practical performance of the proposed scheme in real setups
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