2,514 research outputs found
CommuniSense: Crowdsourcing Road Hazards in Nairobi
Nairobi is one of the fastest growing metropolitan cities and a major
business and technology powerhouse in Africa. However, Nairobi currently lacks
monitoring technologies to obtain reliable data on traffic and road
infrastructure conditions. In this paper, we investigate the use of mobile
crowdsourcing as means to gather and document Nairobi's road quality
information. We first present the key findings of a city-wide road quality
survey about the perception of existing road quality conditions in Nairobi.
Based on the survey's findings, we then developed a mobile crowdsourcing
application, called CommuniSense, to collect road quality data. The application
serves as a tool for users to locate, describe, and photograph road hazards. We
tested our application through a two-week field study amongst 30 participants
to document various forms of road hazards from different areas in Nairobi. To
verify the authenticity of user-contributed reports from our field study, we
proposed to use online crowdsourcing using Amazon's Mechanical Turk (MTurk) to
verify whether submitted reports indeed depict road hazards. We found 92% of
user-submitted reports to match the MTurkers judgements. While our prototype
was designed and tested on a specific city, our methodology is applicable to
other developing cities.Comment: In Proceedings of 17th International Conference on Human-Computer
Interaction with Mobile Devices and Services (MobileHCI 2015
Compressed sensing with combinatorial designs: theory and simulations
In 'An asymptotic result on compressed sensing matrices', a new construction
for compressed sensing matrices using combinatorial design theory was
introduced. In this paper, we use deterministic and probabilistic methods to
analyse the performance of matrices obtained from this construction. We provide
new theoretical results and detailed simulations. These simulations indicate
that the construction is competitive with Gaussian random matrices, and that
recovery is tolerant to noise. A new recovery algorithm tailored to the
construction is also given.Comment: 18 pages, 3 figure
Medical Professionalism: Who Needs It?
Anecdotal and public opinion evidence that respect for physicians may be decreasing could be explained by a decline, or perceived decline, in medical professionalism. Causes for the latter are discussed, and physician embrace of “the new professionalism” is suggested
Variable sediment oxygen uptake in response to dynamic forcing
Seiche-induced turbulence and the vertical distribution of dissolved oxygen above and within the sediment were analyzed to evaluate the sediment oxygen uptake rate (JO2), diffusive boundary layer thickness (δDBL), and sediment oxic zone depth (zmax) in situ. High temporal-resolution microprofiles across the sediment-water interface and current velocity data within the bottom boundary layer in a medium-sized mesotrophic lake were obtained during a 12-h field study. We resolved the dynamic forcing of a full 8-h seiche cycle and evaluated JO2 from both sides of the sediment-water interface. Turbulence (characterized by the energy dissipation rate, ε), the vertical distribution of dissolved oxygen across the sediment-water interface (characterized by δDBL and zmax), JO2, and the sediment oxygen consumption rate (RO2) are all strongly correlated in our freshwater system. Seiche-induced turbulence shifted from relatively active (ε = 1.2 × 10-8 W kg-1) to inactive (ε = 7.8 × 10-12 W kg-1). In response to this dynamic forcing, δDBL increased from 1.0 mm to the point of becoming undefined, zmax decreased from 2.2 to 0.3 mm as oxygen was depleted from the sediment, and JO2 decreased from 7.0 to 1.1 mmol m-2 d-1 over a time span of hours. JO2 and oxygen consumption were found to be almost equivalent (within ~ 5% and thus close to steady state), with RO2 adjusting rapidly to changes in JO2. Our results reveal the transient nature of sediment oxygen uptake and the importance of accurately characterizing turbulence when estimating JO2
Decompositions of complete graphs into cycles of arbitrary lengths
We show that the complete graph on vertices can be decomposed into
cycles of specified lengths if and only if is odd, for , and . We also show
that the complete graph on vertices can be decomposed into a perfect
matching and cycles of specified lengths if and only if
is even, for , and .Comment: 182 pages, 0 figures, A condensed version of this paper was published
as "Cycle decompositions V: Complete graphs into cycles of arbitrary lengths"
(see reference [24]). Here, we include supplementary data and some proofs
which were omitted from that pape
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