1,721,242 research outputs found
State-Selective Ionization of Nitrogen in the X2Σ+gν+ =0 and ν+ =1 States by Two-Color (1+1) Photon Excitation Near Threshold
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effective resolution concepts for lidar observations
Full text linkSince its establishment in 2000, EARLINET (European Aerosol Research Lidar
NETwork) has provided, through its database, quantitative aerosol
properties, such as aerosol backscatter and aerosol extinction coefficients,
the latter only for stations able to retrieve it independently (from Raman
or high-spectral-resolution lidars). These coefficients are stored in terms
of vertical profiles, and the EARLINET database also includes the details of
the range resolution of the vertical profiles. In fact, the algorithms used
in the lidar data analysis often alter the spectral content of the data,
mainly acting as low-pass filters to reduce the high-frequency noise. Data
filtering is described by the digital signal processing (DSP) theory as a
convolution sum: each filtered signal output at a given range is the result
of a linear combination of several signal input data samples (relative to
different ranges from the lidar receiver), and this could be seen as a loss
of range resolution of the output signal. Low-pass filtering always
introduces distortions in the lidar profile shape. Thus, both the removal of
high frequency, i.e., the removal of details up to a certain spatial
extension, and the spatial distortion produce a reduction of the range
resolution.
This paper discusses the determination of the effective resolution (ERes) of
the vertical profiles of aerosol properties retrieved from lidar data. Large
attention has been dedicated to providing an assessment of the impact of
low-pass filtering on the effective range resolution in the retrieval
procedure
Ultrahigh-Resolution (1+1) Photoionization Spectroscopy of KrI:Hyperfine Structures, Isotope Shifts and Lifetimes for the n=5,6,7 4p5ns Rydberg States
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