88,927 research outputs found
Narrow scope for resolution-limit-free community detection
Detecting communities in large networks has drawn much attention over the
years. While modularity remains one of the more popular methods of community
detection, the so-called resolution limit remains a significant drawback. To
overcome this issue, it was recently suggested that instead of comparing the
network to a random null model, as is done in modularity, it should be compared
to a constant factor. However, it is unclear what is meant exactly by
"resolution-limit-free", that is, not suffering from the resolution limit.
Furthermore, the question remains what other methods could be classified as
resolution-limit-free. In this paper we suggest a rigorous definition and
derive some basic properties of resolution-limit-free methods. More
importantly, we are able to prove exactly which class of community detection
methods are resolution-limit-free. Furthermore, we analyze which methods are
not resolution-limit-free, suggesting there is only a limited scope for
resolution-limit-free community detection methods. Finally, we provide such a
natural formulation, and show it performs superbly
A widely tunable 10-m quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy
We report the coherent phase-locking of a quantum cascade laser (QCL) at
10-m to the secondary frequency standard of this spectral region, a CO2
laser stabilized on a saturated absorption line of OsO4. The stability and
accuracy of the standard are transferred to the QCL resulting in a line width
of the order of 10 Hz, and leading to our knowledge to the narrowest QCL to
date. The locked QCL is then used to perform absorption spectroscopy spanning 6
GHz of NH3 and methyltrioxorhenium, two species of interest for applications in
precision measurements.Comment: 5 pages, 4 figure
J Fluorescence
The scope of this paper is to illustrate the need for an improved quality assurance in fluorometry. For this purpose, instrumental sources of error and their influences on the reliability and comparability of fluorescence data are highlighted for frequently used photoluminescence techniques ranging from conventional macro- and microfluorometry over fluorescence microscopy and flow cytometry to microarray technology as well as in vivo fluorescence imaging. Particularly, the need for and requirements on fluorescence standards for the characterization and performance validation of fluorescence instruments, to enhance the comparability of fluorescence data, and to enable quantitative fluorescence analysis are discussed. Special emphasis is dedicated to spectral fluorescence standards and fluorescence intensity standards
Titan Science with the James Webb Space Telescope (JWST)
The James Webb Space Telescope (JWST), scheduled for launch in 2018, is the
successor to the Hubble Space Telescope (HST) but with a significantly larger
aperture (6.5 m) and advanced instrumentation focusing on infrared science
(0.6-28.0 m ). In this paper we examine the potential for scientific
investigation of Titan using JWST, primarily with three of the four
instruments: NIRSpec, NIRCam and MIRI, noting that science with NIRISS will be
complementary. Five core scientific themes are identified: (i) surface (ii)
tropospheric clouds (iii) tropospheric gases (iv) stratospheric composition and
(v) stratospheric hazes. We discuss each theme in depth, including the
scientific purpose, capabilities and limitations of the instrument suite, and
suggested observing schemes. We pay particular attention to saturation, which
is a problem for all three instruments, but may be alleviated for NIRCam
through use of selecting small sub-arrays of the detectors - sufficient to
encompass Titan, but with significantly faster read-out times. We find that
JWST has very significant potential for advancing Titan science, with a
spectral resolution exceeding the Cassini instrument suite at near-infrared
wavelengths, and a spatial resolution exceeding HST at the same wavelengths. In
particular, JWST will be valuable for time-domain monitoring of Titan, given a
five to ten year expected lifetime for the observatory, for example monitoring
the seasonal appearance of clouds. JWST observations in the post-Cassini period
will complement those of other large facilities such as HST, ALMA, SOFIA and
next-generation ground-based telescopes (TMT, GMT, EELT).Comment: 50 pages, including 22 figures and 2 table
The Search for Extraterrestrial Intelligence (SETI)
A bibliography of reports concerning the Search for Extraterrestrial Intelligence is presented. Cosmic evolution, space communication, and technological advances are discussed along with search strategies and search systems
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