177,186 research outputs found
Does “Evaluating Journal Quality and the Association for Information Systems Senior Scholars Journal Basket…” Support the Basket with Bibliometric Measures?
We re-examine “Evaluating Journal Quality and the Association for Information Systems Senior Scholars Journal Basket…” by Lowry et al. (2013). They sought to use bibliometric methods to validate the Basket as the eight top quality journals that are “strictly speaking, IS journals” (Lowry et al., 2013, pp. 995, 997). They examined 21 journals out of 140 journals considered as possible IS journals. We also expand the sample to 73 of the 140 journals. Our sample includes a wider range of approaches to IS, although all were suggested by IS scholars in a survey by Lowry and colleagues. We also use the same sample of 21 journals in Lowry et al. with the same methods of analysis so far as possible. With the narrow sample, we replicate Lowry et al. as closely as we can, whereas with the broader sample we employ a conceptual replication. This latter replication also employs alternative methods. For example, we consider citations (a quality measure) and centrality (a relevance measure in this context) as distinct, rather than merging them as in Lowry et al. High centrality scores from the sample of 73 journals do not necessarily indicate close connections with IS. Therefore, we determine which journals are of high quality and closely connected with the Basket and with their sample. These results support the broad purpose of Lowry et al., finding a wider set of high quality and relevant journals than just MISQ and ISR, and find a wider set of relevant, top quality journals
Magnetic Field Tomography in Nearby Galaxies with the Square Kilometre Array
Magnetic fields play an important role in shaping the structure and evolution
of the interstellar medium (ISM) of galaxies, but the details of this
relationship remain unclear. With SKA1, the 3D structure of galactic magnetic
fields and its connection to star formation will be revealed. A highly
sensitive probe of the internal structure of the magnetoionized ISM is the
partial depolarization of synchrotron radiation from inside the volume.
Different configurations of magnetic field and ionized gas within the
resolution element of the telescope lead to frequency-dependent changes in the
observed degree of polarization. The results of spectro-polarimetric
observations are tied to physical structure in the ISM through comparison with
detailed modeling, supplemented with the use of new analysis techniques that
are being actively developed and studied within the community such as Rotation
Measure Synthesis. The SKA will enable this field to come into its own and
begin the study of the detailed structure of the magnetized ISM in a sample of
nearby galaxies, thanks to its extraordinary wideband capabilities coupled with
the combination of excellent surface brightness sensitivity and angular
resolution.Comment: 11 pages, 1 figure; to appear as part of 'Cosmic Magnetism' in
Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)10
Utility of correlation techniques in gravity and magnetic interpretation
Two methods of quantitative combined analysis, internal correspondence and clustering, are presented. Model studies are used to illustrate implementation and interpretation procedures of these methods, particularly internal correspondence. Analysis of the results of applying these methods to data from the midcontinent and a transcontinental profile show they can be useful in identifying crustal provinces, providing information on horizontal and vertical variations of physical properties over province size zones, validating long wave-length anomalies, and isolating geomagnetic field removal problems. Thus, these techniques are useful in considering regional data acquired by satellites
Multimedia information technology and the annotation of video
The state of the art in multimedia information technology has not progressed to the point where a single solution is available to meet all reasonable needs of documentalists and users of video archives. In general, we do not have an optimistic view of the usability of new technology in this domain, but digitization and digital power can be expected to cause a small revolution in the area of video archiving. The volume of data leads to two views of the future: on the pessimistic side, overload of data will cause lack of annotation capacity, and on the optimistic side, there will be enough data from which to learn selected concepts that can be deployed to support automatic annotation. At the threshold of this interesting era, we make an attempt to describe the state of the art in technology. We sample the progress in text, sound, and image processing, as well as in machine learning
Are There Different Populations of Flux Ropes in the Solar Wind?
Flux ropes are twisted magnetic structures, which can be detected by in situ
measurements in the solar wind. However, different properties of detected flux
ropes suggest different types of flux-rope population. As such, are there
different populations of flux ropes? The answer is positive, and is the result
of the analysis of four lists of flux ropes, including magnetic clouds (MCs),
observed at 1 AU. The in situ data for the four lists have been fitted with the
same cylindrical force-free field model, which provides an estimation of the
local flux-rope parameters such as its radius and orientation. Since the
flux-rope distributions have a large dynamic range, we go beyond a simple
histogram analysis by developing a partition technique that uniformly
distributes the statistical fluctuations over the radius range. By doing so, we
find that small flux ropes with radius R<0.1 AU have a steep power-law
distribution in contrast to the larger flux ropes (identified as MCs), which
have a Gaussian-like distribution. Next, from four CME catalogs, we estimate
the expected flux-rope frequency per year at 1 AU. We find that the predicted
numbers are similar to the frequencies of MCs observed in situ. However, we
also find that small flux ropes are at least ten times too abundant to
correspond to CMEs, even to narrow ones. Investigating the different possible
scenarios for the origin of those small flux ropes, we conclude that these
twisted structures can be formed by blowout jets in the low corona or in
coronal streamers.Comment: 24 pages, 6 figure
New Low Accretion-Rate Magnetic Binary Systems and their Significance for the Evolution of Cataclysmic Variables
Discoveries of two new white dwarf plus M star binaries with striking optical
cyclotron emission features from the Sloan Digital Sky Survey (SDSS) brings to
six the total number of X-ray faint, magnetic accretion binaries that accrete
at rates < 10^{-13} Msun/yr, or <1% of the values normally encountered in
cataclysmic variables. This fact, coupled with donor stars that underfill their
Roche lobes and very cool white dwarfs, brand the binaries as post
common-envelope systems whose orbits have not yet decayed to the point of
Roche-lobe contact. They are pre-magnetic CVs, or pre-Polars. The systems
exhibit spin/orbit synchronism and apparently accrete by efficient capture of
the stellar wind from the secondary star, a process that has been dubbed a
``magnetic siphon''. Because of this, period evolution of the binaries will
occur solely by gravitational radiation, which is very slow for periods >3 hr.
Optical surveys for the cyclotron harmonics appear to be the only means of
discovery, so the space density of pre-Polars could rival that of Polars, and
the binaries provide an important channel of progenitors (in addition to the
asynchronous Intermediate Polars). Both physical and SDSS observational
selection effects are identified that may help to explain the clumping of all
six systems in a narrow range of magnetic field strength around 60 MG.Comment: 25 pages, 13 figures, Accepted to Ap
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