5,460 research outputs found
A Characterization of Cybersecurity Posture from Network Telescope Data
Data-driven understanding of cybersecurity posture is an important problem
that has not been adequately explored. In this paper, we analyze some real data
collected by CAIDA's network telescope during the month of March 2013. We
propose to formalize the concept of cybersecurity posture from the perspectives
of three kinds of time series: the number of victims (i.e., telescope IP
addresses that are attacked), the number of attackers that are observed by the
telescope, and the number of attacks that are observed by the telescope.
Characterizing cybersecurity posture therefore becomes investigating the
phenomena and statistical properties exhibited by these time series, and
explaining their cybersecurity meanings. For example, we propose the concept of
{\em sweep-time}, and show that sweep-time should be modeled by stochastic
process, rather than random variable. We report that the number of attackers
(and attacks) from a certain country dominates the total number of attackers
(and attacks) that are observed by the telescope. We also show that
substantially smaller network telescopes might not be as useful as a large
telescope
River Run Off Measurement With SAR Along Track Interferometry
The paper summarizes the need for global space borne river run-off measurements. It reports about an airborne SAR experiment aimed to measure the surface velocity of the river Isar in Bavaria / Germany. The results from two different SAR techniques, including Along Track Interferometry (ATI) show good correspondence. Finally suggestions for further studies are given
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Remarkable dynamics of nanoparticles in the urban atmosphere
Nanoparticles emitted from road traffic are the largest source of respiratory exposure for the general public living in urban areas. It has been suggested that the adverse health effects of airborne particles may scale with the airborne particle number, which if correct, focuses attention on the nanoparticle (less than 100 nm) size range which dominates the number count in urban areas. Urban measurements of particle size distributions have tended to show a broadly similar pattern dominated by a mode centred on 20–30 nm diameter particles emitted by diesel engine exhaust. In this paper we report the results of measurements of particle number concentration and size distribution made in a major London park as well as on the BT Tower, 160 m high. These measurements taken during the REPARTEE project (Regents Park and BT Tower experiment) show a remarkable shift in particle size distributions with major losses of the smallest particle class as particles are advected away from the traffic source. In the Park, the traffic related mode at 20–30 nm diameter is much reduced with a new mode at <10 nm. Size distribution measurements also revealed higher number concentrations of sub-50 nm particles at the BT Tower during days affected by higher turbulence as determined by Doppler Lidar measurements and indicate a loss of nanoparticles from air aged during less turbulent conditions. These results suggest that nanoparticles are lost by evaporation, rather than coagulation processes. The results have major implications for understanding the impacts of traffic-generated particulate matter on human health
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