3,706 research outputs found
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
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
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
Enhancement of callus induction and regeneration efficiency from embryo cultures of Datura stramonium by adjusting carbon sources and concentrations
Carbon source in the medium is considered to be an essential component for the high production costs of callus and plantlets in tissue culture. We report here the establishment of an efficient tissue culture cycle (callus induction and plant regeneration) for Datura stramonium by adjusting carbon sources and concentrations. Embryo explants of D. stramonium L. were cultured in vitro with six different carbon sources (sucrose, glucose, fructose, galactose, maltose and lactose) and four concentrations (1, 2, 3 and 4%) for callus induction. After that, the best carbon sources for regeneration were investigated with four different carbon sources (sucrose, glucose, fructose and sorbitol) and four concentrations (1, 2, 3 and 4%). The best sugar for callus induction was 2% lactose. The medium containing 3% glucose shows the higher regeneration.Key words: Datura stramonium L., carbon source, callus induction, plant regeneration and embryo culture
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