1,082 research outputs found
Algebraic Attack on the Alternating Step(r,s)Generator
The Alternating Step(r,s) Generator, ASG(r,s), is a clock-controlled sequence
generator which is recently proposed by A. Kanso. It consists of three
registers of length l, m and n bits. The first register controls the clocking
of the two others. The two other registers are clocked r times (or not clocked)
(resp. s times or not clocked) depending on the clock-control bit in the first
register. The special case r=s=1 is the original and well known Alternating
Step Generator. Kanso claims there is no efficient attack against the ASG(r,s)
since r and s are kept secret. In this paper, we present an Alternating Step
Generator, ASG, model for the ASG(r,s) and also we present a new and efficient
algebraic attack on ASG(r,s) using 3(m+n) bits of the output sequence to find
the secret key with O((m^2+n^2)*2^{l+1}+ (2^{m-1})*m^3 + (2^{n-1})*n^3)
computational complexity. We show that this system is no more secure than the
original ASG, in contrast to the claim of the ASG(r,s)'s constructor.Comment: 5 pages, 2 figures, 2 tables, 2010 IEEE International Symposium on
Information Theory (ISIT2010),June 13-18, 2010, Austin, Texa
Evaluation of bacteriological and chemical quality of dialysis water and fluid in Isfahan, central Iran
Background: Chemical and microbial quality of water used in hemodialysis play key roles in a number of dialysisrelated complications. In order to avoid the complications and to guarantee safety and health of patients therefore, vigorous control of water quality is essential. The objective of present study was to investigate the chemical and bacteriological characteristics of water used in dialysis centers of five hospitals in Isfahan, central Iran. Methods: A total of 30 water samples from the input of dialysis purification system and dialysis water were analyzed for chemical parameters. Heterotrophic plate count and endotoxin concentration of drinking water, dialysis water and dialysis fluid of 40 machines were also monitored over a 5-month period in 2011-2012. Results: Concentration of the determined chemicals (copper, zinc, sulfate, fluoride, chloramines and free chlorine) did not exceed the recommended concentration by the Association for the Advancement of Medical Instrumentation (AAMI) exclude lead, nitrate, aluminum and calcium. Furthermore, the magnesium; cadmium and chromium concentration exceeded the maximum level in some centers. No contamination with heterotrophic bacteria was observed in all samples, while the AMMI standard for endotoxin level in dialysis fluid (<2 EU/ml) was achieved in 95 of samples. Conclusion: Dialysis water and fluid failed to meet the all chemical and bacteriological requirements for hemodialysis. To minimize the risk of contaminants for hemodialysis patients therefore, a water quality management program including monitoring, maintenance and development of water treatment system in hemodialysis centers is extremely important. In addition, an appropriate disinfection program is needed to guarantee better control of bacterial growth and biofilm formation. © 2016, Iranian Journal of Public Health. All rights reserved
Broadcast Caching Networks with Two Receivers and Multiple Correlated Sources
The correlation among the content distributed across a cache-aided broadcast
network can be exploited to reduce the delivery load on the shared wireless
link. This paper considers a two-user three-file network with correlated
content, and studies its fundamental limits for the worst-case demand. A class
of achievable schemes based on a two-step source coding approach is proposed.
Library files are first compressed using Gray-Wyner source coding, and then
cached and delivered using a combination of correlation-unaware cache-aided
coded multicast schemes. The second step is interesting in its own right and
considers a multiple-request caching problem, whose solution requires coding in
the placement phase. A lower bound on the optimal peak rate-memory trade-off is
derived, which is used to evaluate the performance of the proposed scheme. It
is shown that for symmetric sources the two-step strategy achieves the lower
bound for large cache capacities, and it is within half of the joint entropy of
two of the sources conditioned on the third source for all other cache sizes.Comment: in Proceedings of Asilomar Conference on Signals, Systems and
Computers, Pacific Grove, California, November 201
Induction of triploidy in grass carp Ctenopharyngodon idella Valenciennes, 1844: comparison of cold & heat shocks
Triploidy in grass carp, Ctenopharyngodon idella Valenciennes, 1844, was induced on fertilized eggs to compare cold and heat shocks. Two simplified methods explained for verification of triploidy in grass carp. The cold shock (7 ËšC) was given in three treatments for 30 min starting 2.0, 2.5 and 4.0 min after fertilization. In cold shock, the start point (2.0 min after fertilization) showed the highest rate of triploidy (60.9%). Heat shocks were given at 38 ËšC, 40 ËšC and 42 ËšC, at 4.0 min after fertilization and lasted for 1.0 min. Produced larvae using heat shock 38 ËšC showed 10.8% triploidy, but no signs of triploidy were seen in other heat shock treatments. Verification of triploidy in grass carp was carried out using karyotyping and measurment of erythrocytes surface area and volume in fingerlings. Ratio of erythrocytes dimention and the size of their nuclei in triploids to diploids was 2.35 and 1.80, respectively. Comparison of results obtained from the application of cold and heat shocks indicated that cold shocks are more effective than heat shocks in the induction of triploidy in grass carp
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