206 research outputs found
Cyclone Codes
We introduce Cyclone codes which are rateless erasure resilient codes. They
combine Pair codes with Luby Transform (LT) codes by computing a code symbol
from a random set of data symbols using bitwise XOR and cyclic shift
operations. The number of data symbols is chosen according to the Robust
Soliton distribution. XOR and cyclic shift operations establish a unitary
commutative ring if data symbols have a length of bits, for some prime
number . We consider the graph given by code symbols combining two data
symbols. If such random pairs are given for data symbols, then a
giant component appears, which can be resolved in linear time. We can extend
Cyclone codes to data symbols of arbitrary even length, provided the Goldbach
conjecture holds.
Applying results for this giant component, it follows that Cyclone codes have
the same encoding and decoding time complexity as LT codes, while the overhead
is upper-bounded by those of LT codes. Simulations indicate that Cyclone codes
significantly decreases the overhead of extra coding symbols
Suitability of a CMV/EGFP cassette to monitor stable expression from human artificial chromosomes but not transient transfer in the cells forming viable clones
Human artificial chromosomes (HACs) were generated by transfer of telomerized PAC constructs containing alpha satellite DNA of various human chromosomes. To monitor which cells took up constructs and subsequently formed stable clones under blasticidin S (BS) selection, a CMV/EGFP expression cassette was inserted into a HAC construct based on chromosome 5 alpha satellite DNA (142 kb). Lipofection into HT1080 cells resulted in a small proportion of cells exhibiting bright green fluorescence on day 1. Areas containing such early green cells were marked, and plates monitored over 2 weeks. In only one out of 41 marked areas, a viable clone developed. In the remaining 40 areas, the green cells ceased division at 1-8 cells. In contrast, outside the marked areas, 16 stable clones formed which did not exhibit green fluorescence during the first cell divisions, but all cells of each became green around day 4 -6. Fluorescence in situ hybridization (FISH) analysis of isolated clonal lines demonstrated low copy HAC formation without integration. We conclude that transient expression of an EGFP marker on HAC DNA is not a suitable means for the identification of the proportion of transfected cells which are capable of forming viable clones. One explanation could be that the high copy number required to consistently detect transient EGFP expression (Schindelhauer and Laner, 2002) impairs viability and clone formation. Copyright (C) 2004 S. Karger AG, Basel
Simulation of a first prototypical 3D solution for Indoor Localization based on Directed and Reflected Signals
We introduce a solution for a specific case of Indoor Localization which
involves a directed signal, a reflected signal from the wall and the time
difference between them. This solution includes robust localization with a
given wall, finding the right wall from a group of walls, obtaining the
reflecting wall from measurements, using averaging techniques for improving
measurements with errors and successfully grouping measurements regarding
reflecting walls. It also includes performing self-calibration by computation
of wall distance and direction introducing algorithms such as All pairs,
Disjoint pairs and Overlapping pairs and clustering walls based on Inversion
and Gnomonic Projection. Several of these algorithms are then compared in order
to ameliorate the effects of measurement errors.Comment: 16 page
Seminar Delay-Tolerant Networks
Abstract In this paper, I introduce main concepts of delay-tolerant networks and their architecture. Delay-tolerant networks are designed to operate in environments characterized by very long delay paths and frequent network partitions. In the end, I give results of performance evaluation of the DTN store-and-forward approach compared to traditional Internet data transfer protocols. The paper does not introduce novel approaches created by the author himself but rather should be seen as a summarized review of reference papers
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