103,441 research outputs found
Interactive tag maps and tag clouds for the multiscale exploration of large spatio-temporal datasets
'Tag clouds' and 'tag maps' are introduced to represent geographically referenced text. In combination, these aspatial and spatial views are used to explore a large structured spatio-temporal data set by providing overviews and filtering by text and geography. Prototypes are implemented using freely available technologies including Google Earth and Yahoo! 's Tag Map applet. The interactive tag map and tag cloud techniques and the rapid prototyping method used are informally evaluated through successes and limitations encountered. Preliminary evaluation suggests that the techniques may be useful for generating insights when visualizing large data sets containing geo-referenced text strings. The rapid prototyping approach enabled the technique to be developed and evaluated, leading to geovisualization through which a number of ideas were generated. Limitations of this approach are reflected upon. Tag placement, generalisation and prominence at different scales are issues which have come to light in this study that warrant further work
The XMM-Newton view of the central degrees of the Milky Way
The deepest XMM-Newton mosaic map of the central 1.5 deg of the Galaxy is
presented, including a total of about 1.5 Ms of EPIC-pn cleaned exposures in
the central 15" and about 200 ks outside. This compendium presents broad-band
X-ray continuum maps, soft X-ray intensity maps, a decomposition into spectral
components and a comparison of the X-ray maps with emission at other
wavelengths. Newly-discovered extended features, such as supernova remnants
(SNRs), superbubbles and X-ray filaments are reported. We provide an atlas of
extended features within +-1 degree of Sgr A*. We discover the presence of a
coherent X-ray emitting region peaking around G0.1-0.1 and surrounded by the
ring of cold, mid-IR-emitting material known from previous work as the "Radio
Arc Bubble" and with the addition of the X-ray data now appears to be a
candidate superbubble. Sgr A's bipolar lobes show sharp edges, suggesting that
they could be the remnant, collimated by the circumnuclear disc, of a SN
explosion that created the recently discovered magnetar, SGR J1745-2900. Soft
X-ray features, most probably from SNRs, are observed to fill holes in the dust
distribution, and to indicate a direct interaction between SN explosions and
Galactic center (GC) molecular clouds. We also discover warm plasma at high
Galactic latitude, showing a sharp edge to its distribution that correlates
with the location of known radio/mid-IR features such as the "GC Lobe". These
features might be associated with an inhomogeneous hot "atmosphere" over the
GC, perhaps fed by continuous or episodic outflows of mass and energy from the
GC region.Comment: MNRAS published online. See www.mpe.mpg.de/heg/gc/ for a higher
resolution version of the figure
Star formation towards the Scutum tangent region and the effects of Galactic environment
By positional matching to the catalogue of Galactic Ring Survey molecular
clouds, we have derived distances to 793 Bolocam Galactic Plane Survey (BGPS)
sources out of a possible 806 located within the region defined by Galactic
longitudes l = 28.5 degr to 31.5 degr and latitudes |b| < 1 degr. This section
of the Galactic Plane contains several major features of Galactic structure at
different distances, mainly mid-arm sections of the Perseus and Sagittarius
spiral arms and the tangent of the Scutum-Centarus arm, which is coincident
with the end of the Galactic Long Bar. By utilising the catalogued cloud
distances plus new kinematic distance determinations, we are able to separate
the dense BGPS clumps into these three main line-of-sight components to look
for variations in star-formation properties that might be related to the
different Galactic environments. We find no evidence of any difference in
either the clump mass function or the average clump formation efficiency (CFE)
between these components that might be attributed to environmental effects on
scales comparable to Galactic-structure features.
Despite having a very high star-formation rate, and containing at least one
cloud with a very high CFE, the star formation associated with the
Scutum-Centarus tangent does not appear to be in any way abnormal or different
to that in the other two spiral-arm sections. Large variations in the CFE are
found on the scale of individual clouds, however, which may be due to local
triggering agents as opposed to the large-scale Galactic structure.Comment: 11 pages, 8 figures. Accepted for publication in the Monthly Notices
of the Royal Astronomical Societ
A threshold secure data sharing scheme for federated clouds
Cloud computing allows users to view computing in a new direction, as it uses
the existing technologies to provide better IT services at low-cost. To offer
high QOS to customers according SLA, cloud services broker or cloud service
provider uses individual cloud providers that work collaboratively to form a
federation of clouds. It is required in applications like Real-time online
interactive applications, weather research and forecasting etc., in which the
data and applications are complex and distributed. In these applications secret
data should be shared, so secure data sharing mechanism is required in
Federated clouds to reduce the risk of data intrusion, the loss of service
availability and to ensure data integrity. So In this paper we have proposed
zero knowledge data sharing scheme where Trusted Cloud Authority (TCA) will
control federated clouds for data sharing where the secret to be exchanged for
computation is encrypted and retrieved by individual cloud at the end. Our
scheme is based on the difficulty of solving the Discrete Logarithm problem
(DLOG) in a finite abelian group of large prime order which is NP-Hard. So our
proposed scheme provides data integrity in transit, data availability when one
of host providers are not available during the computation.Comment: 8 pages, 3 Figures, International Journal of Research in Computer
Science 2012. arXiv admin note: text overlap with arXiv:1003.3920 by other
author
Tactile Mapping and Localization from High-Resolution Tactile Imprints
This work studies the problem of shape reconstruction and object localization
using a vision-based tactile sensor, GelSlim. The main contributions are the
recovery of local shapes from contact, an approach to reconstruct the tactile
shape of objects from tactile imprints, and an accurate method for object
localization of previously reconstructed objects. The algorithms can be applied
to a large variety of 3D objects and provide accurate tactile feedback for
in-hand manipulation. Results show that by exploiting the dense tactile
information we can reconstruct the shape of objects with high accuracy and do
on-line object identification and localization, opening the door to reactive
manipulation guided by tactile sensing. We provide videos and supplemental
information in the project's website
http://web.mit.edu/mcube/research/tactile_localization.html.Comment: ICRA 2019, 7 pages, 7 figures. Website:
http://web.mit.edu/mcube/research/tactile_localization.html Video:
https://youtu.be/uMkspjmDbq
The Thermal Evolution of Ices in the Environments of Newly Formed Stars: The CO_2 Diagnostic
Archival data from the Infrared Spectrometer of the Spitzer Space Telescope are used to study the 15 μm absorption feature of solid CO_2 toward 28 young stellar objects (YSOs) of approximately solar mass. Fits to the absorption profile using laboratory spectra enable categorization according to the degree of thermal processing of the ice matrix that contains the CO_2. The majority of YSOs in our sample (20 out of 28) are found to be consistent with a combination of polar (H_2O-rich) and nonpolar (CO-rich) ices at low temperature; the remainder exhibit profile structure consistent with partial crystallization as the result of significant heating. Ice-phase column densities of CO_2 are determined and compared with those of other species. Lines of sight with crystallization signatures in their spectra are found to be systematically deficient in solid-phase CO, as expected if CO is being sublimated in regions where the ices are heated to crystallization temperatures. Significant variation is found in the CO2 abundance with respect to both H_2O (the dominant ice constituent) and total dust column (quantified by the extinction, AV ). YSOs in our sample display typically higher CO_2 concentrations (independent of evidence for thermal processing) in comparison to quiescent regions of the prototypical cold molecular cloud. This suggests that enhanced CO_2 production is driven by photochemical reactions in proximity to some YSOs, and that photoprocessing and thermal processing may occur independently
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