1,391 research outputs found
Earth study from space
The significance that space studies are making to all Earth sciences in the areas of geography, geodesy, cartography, geology, meteorology, oceanology, agronomy, and ecology is discussed. It is predicted that cosmonautics will result in a revolution in science and technology
Optimal Threshold-Based Multi-Trial Error/Erasure Decoding with the Guruswami-Sudan Algorithm
Traditionally, multi-trial error/erasure decoding of Reed-Solomon (RS) codes
is based on Bounded Minimum Distance (BMD) decoders with an erasure option.
Such decoders have error/erasure tradeoff factor L=2, which means that an error
is twice as expensive as an erasure in terms of the code's minimum distance.
The Guruswami-Sudan (GS) list decoder can be considered as state of the art in
algebraic decoding of RS codes. Besides an erasure option, it allows to adjust
L to values in the range 1<L<=2. Based on previous work, we provide formulae
which allow to optimally (in terms of residual codeword error probability)
exploit the erasure option of decoders with arbitrary L, if the decoder can be
used z>=1 times. We show that BMD decoders with z_BMD decoding trials can
result in lower residual codeword error probability than GS decoders with z_GS
trials, if z_BMD is only slightly larger than z_GS. This is of practical
interest since BMD decoders generally have lower computational complexity than
GS decoders.Comment: Accepted for the 2011 IEEE International Symposium on Information
Theory, St. Petersburg, Russia, July 31 - August 05, 2011. 5 pages, 2 figure
Optimal Thresholds for GMD Decoding with (L+1)/L-extended Bounded Distance Decoders
We investigate threshold-based multi-trial decoding of concatenated codes
with an inner Maximum-Likelihood decoder and an outer error/erasure
(L+1)/L-extended Bounded Distance decoder, i.e. a decoder which corrects e
errors and t erasures if e(L+1)/L + t <= d - 1, where d is the minimum distance
of the outer code and L is a positive integer. This is a generalization of
Forney's GMD decoding, which was considered only for L = 1, i.e. outer Bounded
Minimum Distance decoding. One important example for (L+1)/L-extended Bounded
Distance decoders is decoding of L-Interleaved Reed-Solomon codes. Our main
contribution is a threshold location formula, which allows to optimally erase
unreliable inner decoding results, for a given number of decoding trials and
parameter L. Thereby, the term optimal means that the residual codeword error
probability of the concatenated code is minimized. We give an estimation of
this probability for any number of decoding trials.Comment: Accepted for the 2010 IEEE International Symposium on Information
Theory, Austin, TX, USA, June 13 - 18, 2010. 5 pages, 2 figure
Long-term impact of fecal transplantation in healthy volunteers
Fecal microbiota transplantation (FMT) has been recently approved by FDA for the treatment of refractory recurrent clostridial colitis (rCDI). Success of FTM in treatment of rCDI led to a number of studies investigating the effectiveness of its application in the other gastrointestinal diseases. However, in the majority of studies the effects of FMT were evaluated on the patients with initially altered microbiota. The aim of our study was to estimate effects of FMT on the gut microbiota composition in healthy volunteers and to monitor its long-term outcomes.Peer ReviewedPostprint (published version
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