7,553 research outputs found
A model for dynamic communicators
We develop and test an intuitively simple dynamic network model to describe the type of time-varying connectivity structure present in many technological settings. The model assumes that nodes have an inherent hierarchy governing the emergence of new connections. This idea draws on newly established concepts in online human behaviour concerning the existence of discussion catalysts, who initiate long threads, and online leaders, who trigger feedback. We show that the model captures an important property found in e-mail and voice call data – ‘dynamic communicators’ with sufficient foresight or impact to generate effective links and having an influence that is grossly underestimated by static measures based on snaphots or aggregated data
SAMSON: Spectral Absorption-fluorescence Microscopy System for ON-site-imaging of algae
This paper presents SAMSON, a Spectral Absorption-fluorescence Microscopy
System for ON-site-imaging of algae within a water sample. Designed to be
portable and low-cost for on-site use, the optical sub-system of SAMSON
consists of a mixture of low-cost optics and electronics, designed specifically
to capture both fluorescent and absorption responses from a water sample. The
graphical user interface (GUI) sub-system of SAMSON was designed to enable
flexible visualisation of algae in the water sample in real-time, with the
ability to perform fine-grained exposure control and illumination wavelength
selection. We demonstrate SAMSON's capabilities by equipping the system with
two fluorescent illumination sources and seven absorption illumination sources
to enable the capture of multispectral data from six different algae species
(three from the Cyanophyta phylum (blue-green algae) and three from the
Chlorophyta phylum (green algae)). The key benefit of SAMSON is the ability to
perform rapid acquisition of fluorescence and absorption data at different
wavelengths and magnification levels, thus opening the door for machine
learning methods to automatically identify and enumerate different algae in
water samples using this rich wealth of data
The photon pair source that survived a rocket explosion
We report on the performance of a compact photon pair source that was
recovered intact from a failed space launch. The source had been embedded in a
nanosatellite and was designed to perform pathfinder experiments leading to
global quantum communication networks using spacecraft. Despite the launch
vehicle explosion soon after takeoff?, the nanosatellite was successfully
retrieved from the accident site and the source within it was found to be fully
operational. We describe the assembly technique for the rugged source.
Post-recovery data is compared to baseline measurements collected before the
launch attempt and no degradation in brightness or polarization correlation was
observed. The survival of the source through an extreme environment provides
strong evidence that it is possible to engineer rugged quantum optical systems
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