M. Gonzalez — Page 4

arXiv2009

Understanding the spreading patterns of mobile phone viruses

We model the mobility of mobile phone users to study the fundamental spreading patterns characterizing a mobile virus outbreak. We find that while Bluetooth viruses can reach all susceptible handsets with time, they spread slowly due to human mobility, offering ample opportunities to deploy antiviral software. In contrast, viruses utilizing multimedia messaging services could infect all users in hours, but currently a phase transition on the underlying call graph limits them to only a small fraction of the susceptible users. These results explain the lack of a major mobile virus breakout so far and predict that once a mobile operating system's market share reaches the phase transition point, viruses will pose a serious threat to mobile communications.

physics.data-an↗

arXiv2008

Spitzer observations of extended Lyman-alpha Clouds in the SSA22 field

We present the results of a Spitzer IRAC and MIPS 24 micron study of extended Lyman-alpha clouds (or Lyman-alpha Blobs, LABs) within the SSA22 filamentary structure at z = 3.09. We detect 6/26 LABs in all IRAC filters, four of which are also detected at 24 micron, and find good correspondence with the 850 micron measurements of Geach et al. 2005. An analysis of the rest-frame ultraviolet, optical, near- and mid-infrared colors reveals that these six systems exhibit signs of nuclear activity (AGN)and/or extreme star formation. Notably, they have properties that bridge galaxies dominated by star formation (Lyman-break galaxies; LBGs) and those with AGNs (LBGs classified as QSOs). The LAB systems not detected in all four IRAC bands, on the other hand, are, as a group, consistent with pure star forming systems, similar to the majority of the LBGs within the filament. These results indicate that the galaxies within LABs do not comprise a homogeneous population, though they are also consistent with scenarios in which the gas halos are ionized through a common mechanism such as galaxy-scale winds driven by the galaxies within them, or gravitational heating of the collapsing cloud itself.

astro-ph↗