11,331 research outputs found
Easy 4G/LTE IMSI Catchers for Non-Programmers
IMSI Catchers are tracking devices that break the privacy of the subscribers
of mobile access networks, with disruptive effects to both the communication
services and the trust and credibility of mobile network operators. Recently,
we verified that IMSI Catcher attacks are really practical for the
state-of-the-art 4G/LTE mobile systems too. Our IMSI Catcher device acquires
subscription identities (IMSIs) within an area or location within a few seconds
of operation and then denies access of subscribers to the commercial network.
Moreover, we demonstrate that these attack devices can be easily built and
operated using readily available tools and equipment, and without any
programming. We describe our experiments and procedures that are based on
commercially available hardware and unmodified open source software
Bijectivity of the canonical map for the noncommutative instanton bundle
It is shown that the quantum instanton bundle introduced in Commun. Math.
Phys. 226, 419-432 (2002) has a bijective canonical map and is, therefore, a
coalgebra Galois extension.Comment: Latex, 12 pages. Published versio
Twisted Hochschild Homology of Quantum Hyperplanes
We calculate the Hochschild dimension of quantum hyperplanes using the
twisted Hochschild homology.Comment: 12 pages, LaTe
Why is the nuclear symmetry energy so uncertain at supra-saturation densities?
Within the interacting Fermi gas model for isospin asymmetric nuclear matter,
effects of the in-medium three-body interaction and the two-body short-range
tensor force due to the meson exchange as well as the short-range
nucleon correlation on the high-density behavior of the nuclear symmetry energy
are demonstrated respectively in a transparent way. Possible physics origins of
the extremely uncertain nuclear symmetry energy at supra-saturation densities
are discussed.Comment: Added discussions and revised format. Version to appear in Phys. Rev.
C (2010
Direct Graphene Growth on Insulator
Fabrication of graphene devices is often hindered by incompatibility between
the silicon technology and the methods of graphene growth. Exfoliation from
graphite yields excellent films but is good mainly for research. Graphene grown
on metal has a technological potential but requires mechanical transfer. Growth
by SiC decomposition requires a temperature budget exceeding the technological
limits. These issues could be circumvented by growing graphene directly on
insulator, implying Van der Waals growth. During growth, the insulator acts as
a support defining the growth plane. In the device, it insulates graphene from
the Si substrate. We demonstrate planar growth of graphene on mica surface.
This was achieved by molecular beam deposition above 600{\deg}C. High
resolution Raman scans illustrate the effect of growth parameters and substrate
topography on the film perfection. Ab initio calculations suggest a growth
model. Data analysis highlights the competition between nucleation at surface
steps and flat surface. As a proof of concept, we show the evidence of electric
field effect in a transistor with a directly grown channel.Comment: 13 pages, 6 figure
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