80 research outputs found
VLSI single-chip (255,223) Reed-Solomon encoder with interleaver
The invention relates to a concatenated Reed-Solomon/convolutional encoding system consisting of a Reed-Solomon outer code and a convolutional inner code for downlink telemetry in space missions, and more particularly to a Reed-Solomon encoder with programmable interleaving of the information symbols and code correction symbols to combat error bursts in the Viterbi decoder
Resonance region neutronics of unit cells in fast and thermal reactors
Originally presented as the first author's thesis, (Ph. D.)--in the M.I.T. Dept. of Nuclear Engineering, 1977Includes bibliographical references (p. 226-229)ERDA research and development E(11-1)--2250 UC-79P LMFBR-Physic
Architecture for time or transform domain decoding of reed-solomon codes
Two pipeline (255,233) RS decoders, one a time domain decoder and the other a transform domain decoder, use the same first part to develop an errata locator polynomial .tau.(x), and an errata evaluator polynominal A(x). Both the time domain decoder and transform domain decoder have a modified GCD that uses an input multiplexer and an output demultiplexer to reduce the number of GCD cells required. The time domain decoder uses a Chien search and polynomial evaluator on the GCD outputs .tau.(x) and A(x), for the final decoding steps, while the transform domain decoder uses a transform error pattern algorithm operating on .tau.(x) and the initial syndrome computation S(x), followed by an inverse transform algorithm in sequence for the final decoding steps prior to adding the received RS coded message to produce a decoded output message
Many worlds in one
A generic prediction of inflation is that the thermalized region we inhabit
is spatially infinite. Thus, it contains an infinite number of regions of the
same size as our observable universe, which we shall denote as \O-regions. We
argue that the number of possible histories which may take place inside of an
\O-region, from the time of recombination up to the present time, is finite.
Hence, there are an infinite number of \O-regions with identical histories up
to the present, but which need not be identical in the future. Moreover, all
histories which are not forbidden by conservation laws will occur in a finite
fraction of all \O-regions. The ensemble of \O-regions is reminiscent of
the ensemble of universes in the many-world picture of quantum mechanics. An
important difference, however, is that other \O-regions are unquestionably
real.Comment: 9 pages, 2 figures, comments and references adde
No-Bang Quantum State of the Cosmos
A quantum state of the entire cosmos (universe or multiverse) is proposed
which is the equal mixture of the Giddings-Marolf states that are
asymptotically single de Sitter spacetimes in both past and future and are
regular on the throat or neck of minimal three-volume. That is, states are
excluded that have a big bang or big crunch or which split into multiple
asymptotic de Sitter spacetimes. (For simplicity, transitions between different
values of the cosmological constant are assumed not to occur, though different
positive values are allowed.) The entropy of this mixed state appears to be of
the order of the three-fourths power of the Bekenstein-Hawking A/4 entropy of
de Sitter spacetime. Most of the component pure states do not have rapid
inflation, but when an inflaton is present and the states are weighted by the
volume at the end of inflation, a much smaller number of states may dominate
and give a large amount of inflation and hence may agree with observations.Comment: 18 pages, LaTeX, updated with a few new qualifications and reference
Susskind's Challenge to the Hartle-Hawking No-Boundary Proposal and Possible Resolutions
Given the observed cosmic acceleration, Leonard Susskind has presented the
following argument against the Hartle-Hawking no-boundary proposal for the
quantum state of the universe: It should most likely lead to a nearly empty
large de Sitter universe, rather than to early rapid inflation. Even if one
adds the condition of observers, they are most likely to form by quantum
fluctuations in de Sitter and therefore not see the structure that we observe.
Here I present my own amplified version of this argument and consider possible
resolutions, one of which seems to imply that inflation expands the universe to
be larger than 10^{10^{10^{122}}} Mpc.Comment: 24 pages, LaTeX, 8 references added and a distinction between Linde's
and Vilenkin's tunneling proposal
Manipulating the 3D organization of the largest synthetic yeast chromosome
Whether synthetic genomes can power life has attracted broad interest in the synthetic biology field. Here, we report de novo synthesis of the largest eukaryotic chromosome thus far, synIV, a 1,454,621-bp yeast chromosome resulting from extensive genome streamlining and modification. We developed megachunk assembly combined with a hierarchical integration strategy, which significantly increased the accuracy and flexibility of synthetic chromosome construction. Besides the drastic sequence changes, we further manipulated the 3D structure of synIV to explore spatial gene regulation. Surprisingly, we found few gene expression changes, suggesting that positioning inside the yeast nucleoplasm plays a minor role in gene regulation. Lastly, we tethered synIV to the inner nuclear membrane via its hundreds of loxPsym sites and observed transcriptional repression of the entire chromosome, demonstrating chromosome-wide transcription manipulation without changing the DNA sequences. Our manipulation of the spatial structure of synIV sheds light on higher-order architectural design of the synthetic genomes. </p
Plasma Dynamics
Contains research objectives and summary of research on nineteen research projects split into five sections.National Science Foundation (Grant ENG75-06242-A01)U.S. Energy Research and Development Administration (Contract E(11-1)-2766)U.S. Air Force - Office of Scientific Research (Grant AFOSR-77-3143)U.S. Energy Research and Development Administration (Contract EY-76-C2-02-3070.*000
Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans
Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have
fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in
25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16
regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of
correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP,
while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in
Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium
(LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region.
Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant
enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the
refined data for existing association signals, we estimate that these loci now explain âŒ38.9% of the familial relative risk of PrCa,
an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of
PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent
signals within the same regio
Revisiting âplaceâ in a realist novel: âThinking spaceâ in GaldĂłsâs Torquemada en la hoguera (1889)
Departing from the premise that GaldĂłsâs close engagement with space and place deserves to be at the forefront of scholarly attention, this article provides an in-depth study of their significance in Torquemada en la hoguera. It begins by analysing the relationship between the novelâs locations and the real world, demonstrating that the author codes the city of Madrid to express social concerns and promote reader engagement. It then proceeds to examine the public and private spheres, before highlighting the âplace of the imaginationâ in the novel. It reveals that, as in GaldĂłsâs press articles, reality is used as a springboard in Torquemada en la hoguera and, drawing upon recent theories, it posits that places serve as a framework for engaging readers with contemporary concerns and as an imaginative springboard for GaldĂłs. They trigger what is effectively a âthinking spaceâ for the author and it is through unravelling their significance that we can fully appreciate GaldĂłsâs psychological sensitivity, the novelâs modernity, its symbolic value, and imaginative depth. The article concludes by proposing that GaldĂłsâs works deserve to be re-examined as âNovels of the Geographical Imaginationâ and urges readers to revisit the significance of space and place therein
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