3,646 research outputs found
Glider: A GPU Library Driver for Improved System Security
Legacy device drivers implement both device resource management and
isolation. This results in a large code base with a wide high-level interface
making the driver vulnerable to security attacks. This is particularly
problematic for increasingly popular accelerators like GPUs that have large,
complex drivers. We solve this problem with library drivers, a new driver
architecture. A library driver implements resource management as an untrusted
library in the application process address space, and implements isolation as a
kernel module that is smaller and has a narrower lower-level interface (i.e.,
closer to hardware) than a legacy driver. We articulate a set of device and
platform hardware properties that are required to retrofit a legacy driver into
a library driver. To demonstrate the feasibility and superiority of library
drivers, we present Glider, a library driver implementation for two GPUs of
popular brands, Radeon and Intel. Glider reduces the TCB size and attack
surface by about 35% and 84% respectively for a Radeon HD 6450 GPU and by about
38% and 90% respectively for an Intel Ivy Bridge GPU. Moreover, it incurs no
performance cost. Indeed, Glider outperforms a legacy driver for applications
requiring intensive interactions with the device driver, such as applications
using the OpenGL immediate mode API
On minimal coverings of groups by proper normalizers
For a finite group , a {\it normalizer covering} of is a set of proper
normalizers of some subgroups of whose union is . First we give a
necessary and sufficient condition for a group having a {\it normalizer
covering}. Also, we find some properties of -groups ( a prime) having a
normalizer covering. For a group with a normalizer covering, we define
the minimum cardinality amongst all the normalizer coverings of
. In this article, we show that if is a -group with a normalizer
covering, then or 5. Finally, for any prime and positive
integer , we construct a solvable group with
Ultra-short of pico and femtosecond soliton laser pulse using microring resonator for cancer cells treatment
A system of microring resonators (MRRs) incorporating with an add/drop filter system is presented in which ultra-short single and multi temporal and spatial optical soliton pulses can be simulated and used to thermalbased killing of abnormal cells, tumor and cancer, applicable in nanomedical treatments. This proposed system uses chaotic signals generated by a bright soliton pulse within a nonlinear MRRs system. Interaction between gold nanoparticles and ultra-short femtosecond and picosecond laser pulses holds great interest in laser nanomedicine. By using the appropriate soliton input power and MRRs parameters, required spatial and temporal signals are generated spreading over the spectrum. Results obtained show that smallest single temporal and spatial soliton pulse with FWHM = 712 fs and FWHM = 17.5 pm could be generated respectively. The add/drop filter system is used to generate high capacity ultra-short soliton pulses in the range of nanometer/second and picometer/second
Double Relaxation via AdS/CFT
We exploit the AdS/CFT correspondence to investigate thermalization in an N=2
strongly coupled gauge theory including massless fundamental matter (quark).
More precisely, we consider the response of a zero temperature state of the
gauge theory under variation of an external electric field leading to a
time-dependent current. The holographic dual of the above set-up is given by
introducing a time-dependent electric field on the probe D7-brane embedded in
an AdS_5 X S^5 background. In the dual gravity theory, due to a time-dependent
electric field an apparent horizon forms on the brane which, according to
AdS/CFT dictionary, is the counterpart of the thermalization process in the
gauge theory. We classify different functions for time-dependent electric field
and study their effect on the apparent horizon formation. In the case of pulse
functions where the electric field varies from zero to zero, apart from
non-equilibrium phase, we observe that two apparent horizons form on the brane.
On the gauge theory side, it means that the state of the gauge theory
experiences two different temperatures during the time evolution.Comment: 28 pages, 13 figures, published versio
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