A contextual lightweight arithmetic coder is proposed for lossless compression of medical imagery. Context definition uses causal data from previous symbols coded, an inexpensive yet efficient approach. To further reduce the computational cost, a binary arithmetic coder with fixed-length codewords is adopted, thus avoiding the normalization procedure common in most implementations, and the probability of each context is estimated through bitwise operations. Experimental results are provided for several medical images and compared against state-of-the-art coding techniques, yielding on average improvements between nearly 0.1 and 0.2 bps.

Network coding is an emerging technology that intelligently exploits the store/forward nature of routers to increase the efficiency of the network. Though the concept works in theory, the segregation of coding and routing decisions makes them inapplicable in almost any practical environment. Coding-aware routing takes the network coding a step further to lessen its disadvantages by allowing interlayer communication while making routing decisions. However, most of the existing work exploits coding benefits only for fixed wireless networks, making them dependent on the types of network medium, topology and mobility and thus inapplicable for wired and mobile Ad Hoc networks. The aim of this thesis is to present a generalized algorithm that can detect any possible coding opportunity in a network of any medium, topology and mobility while making routing decisions. We have tested and evaluated our algorithm in six different network topology settings i.e. small wired, big wired, small Ad Hoc network with regular trajectories, big Ad Hoc network with regular trajectories, small Ad Hoc with random trajectories and big Ad Hoc with random trajectories. Improved performance in network throughput, mean queue size and mean end-to-end delay confirms the validity of our algorithm.

L’inactivation du chromosome X (XCI) est un mécanisme qui permet l’extinction transcriptionelle d’un des deux chromosomes X chez la femelle. XCI est régulé par une région spécifique nommée centre de l’inactivation du chromosome (Xic), contenant plusieurs gènes produisant de longs ARNs non codants (lncRNAs). Parmi ces lncRNAs, le transcrit Xist est l’effecteur principal pour l’XCI. Xist peut s’accumuler en cis sur le chromosome et recruter la machinerie qui permettra l’initiation et la propagation de l’extinction transcriptionnelle à l’échelle du chromosome.Le laboratoire d’accueil a identifié un nouveau gène du Xic qui produit le lncRNA Ftx. Dans cette étude, on a pu montrer que l’inactivation du chromosome X est fortement perturbée dans les cellules Ftx-/- et s’accompagne par une forte baisse du niveau d’expression et d’accumulation de Xist. Dans ce contexte, certaines cellules parviennent à maintenir l’expression de Xist mais le profil de couverture du chromosome X par Xist est anormal, présentant un profil diffus ; ceci est associé à une extinction transcriptionnelle déficiente des gènes liés à l’X. Dans les lignées hétérozygotes Ftx+/-, l’expression et l’accumulation de Xist est aussi affectée mais dans une moindre mesure, si bien qu’il apparaît que le nombre de copies de Ftx soit important pour sa fonction. Par ailleurs, l’inactivation du chromosome X dans les cellules Ftx+/- est biaisée de telle sorte que le chromosome X portant une copie fonctionnelle de Ftx est préférentiellement inactivé, suggérant un rôle en cis de Ftx. Ces résultats montrent que Ftx est un activateur de Xist et qu’il est essentiel pour la mise en place de l’inactivation / X-chromosome inactivation (XCI) is a female-specific, chromosome-wide regulatory process that, in eutherians, ensures dosage compensation for X-linked genes between sexes. XCI is controlled by a cis-acting locus on the X-chromosome, the X-inactivation center (Xic), enriched in genes producing long non-coding RNAs (lncRNAs). The Xic-linked gene Xist is the master player of XCI, and produces a lncRNA that accumulates in cis on the X-chromosome and recruits the machinery responsible for initiation and propagation of silencing.The laboratory has identified an additional Xic-linked non-coding gene, Ftx. In this study, we could find that, in female Ftx-/- lines, XCI is strongly impaired, with a significant decrease in the levels of Xist expression and in the percentage of cells showing normal Xist accumulation patterns. Importantly, a high proportion of the cells that still retain Xist expression show abnormal X-chromosome coating and a decreased ability to silence X-linked genes. These data reveal that Ftx is a positive Xist regulator and it is required for proper XCI establishment. In female Ftx+/- lines, the levels of Xist expression and the percentage of cells showing normal Xist accumulation patterns are also decreased, albeit to a lower extent compared to Ftx-/- lines, suggesting that Ftx works in a copy-dependent manner. In addition, a high proportion of Ftx+/- cells display skewed X-inactivation, with preferential inactivation of the wild-type X chromosome. This suggests that Ftx role on Xist accumulation is mostly restricted in cis. Taken together, these results demonstrate that Ftx is required for XCI establishment, where it functions as a strong Xist activator

<p>    We examine new ways in which coding theory and cryptography continue to be  composed together, and show that the composition of these two fields  yield new constructions in the areas of Secure Computation Protocols,  Succinct Interactive Arguments, and Locally Decodable Codes. This  dissertation is a continuation of several decades of research in  composing coding theory and cryptography; examples include secret  sharing, encryption schemes, randomness extraction, pseudo-random number  generation, and the PCP theorem, to name a few. </p> <p>    In Part I of this dissertation, we examine the composition of  coding theory with cryptography, explicitly and implicitly. On the  explicit side, we construct a new family of linear error-correcting  codes, based on algebraic geometric codes, and use this family to  construct new correlation extractors (Ishai et al., FOCS 2009).  Correlation extractors are two-party secure computation protocols for  distilling samples of a leaky correlation (e.g., pre-processed secret  shares that have been exposed to side-channel attacks) into secure and  fresh shares of another correlation (e.g., shares of oblivious  transfer). Our correlation extractors are (nearly) optimal in all  parameters. On the implicit side, we use coding theoretic arguments to  show the security of succinct interactive arguments (Micali, FOCS 1994).  Succinct interactive arguments are a restriction of interactive proofs  (Goldwasser, Micali, Rackoff, STOC 1985) for which security only holds  against computationally bounded provers (i.e., probabilistic polynomial  time), and where the proofs are sub-linear in the size of the statement  being proven. Our new succinct interactive arguments are the first  public-coin, zero-knowledge arguments with time and space efficient  provers: we give two protocols where any NP statement that is verifiable  by a time-T space-S RAM program in is provable time O~(T) and space S *  polylog(T).<br>      In Part II of this dissertation, we examine the composition of  cryptography with coding theory, again explicitly and implicitly,  focusing specifically on locally decodable codes (Katz and Trevisan,  STOC 2000). Locally decodable codes, or LDCs, are error-correcting codes  with super-efficient probabilistic decoding procedures that allow for  decoding individual symbols of the encoded message, without decoding the  entire codeword. On the implicit side, we utilize cryptographic  analysis tools to give a conceptually simpler proof of the so-called  "Hamming-to-InsDel" compiler (Ostrovsky and Paskin-Cherniavsky, ITS  2015). This compiler transforms any Hamming LDC (i.e., a code that is  resilient to bit-flip errors) to another LDC that is resilient to the  broad class of insertion-deletion errors, approximately preserving the  rate and error-tolerance of the code at the cost of a poly-logarithmic  increase in the query complexity. We further extend this compiler to  both the private LDC (Ostrovsky, Pandey, and Sahai, ICALP 2007) setting,  where the encoder and decoder are assumed to share a secret key unknown  to the adversarial channel, and the resource-bounded LDC (Blocki,  Kulkarni, and Zhou, ITC 2020) setting, where the adversarial channel is  assumed to be resource constrained. On the explicit side, we utilize two  cryptographic primitives to give new constructions of alternative  notions of LDCs. First, we use cryptographic puzzles (Bitansky et al.,  ITCS 2016) to construct resource-bounded Hamming LDCs in the standard  model without random oracles, answering an open question of Blocki,  Kulkarni, and Zhou (ITC 2020); we then naturally extend these LDCs to  the InsDel setting via our previously mentioned compiler. Second, we use  digital signature schemes to directly construct computationally relaxed  LDCs (Blocki et al., ITIT 2021) that are resilient to  insertion-deletion errors. Computationally relaxed LDCs allow the  decoder to output an extra symbol signifying it does not know the  correct output and are only secure against probabilistic polynomial time  adversarial channels. To the best of our knowledge, this is the first  such LDC (of any type) resilient against insertion-deletion errors that  does not rely on the aforementioned compiler.</p>

The Interactive Video Data System (IVDS) project began with an initial abstract concept of achieving interactive television by transmitting hidden digital information in the audio of commercials. Over the course of three years such a communication method was successfully developed, the hardware systems to realize the application were designed and built, and several full-scale field tests were conducted. The novel coding scheme satisfies all of the design constraints imposed by the project sponsors. By taking advantage of psychoacoustic properties, the hidden digital signature is inaudible to most human observers yet is detectable by the hardware decoder. The communication method is also robust against most extraneous room noise as well as the wow and flutter of videotape machines. The hardware systems designed for the application have been tested and work as intended. A triple-stage audio amplifier buffers the input signal, eliminates low frequency interference such as human voices, and boosts the filtered result to an appropriate level. A codec samples the filtered and amplified audio, and feeds it into the digital signal processor. The DSP, after applying a pre-emphasis and compensation filter, performs the data extraction by calculating FFTs, compensating for frequency shifts, estimating the digital signature, and verifying the result via a cyclic redundancy check. It then takes action appropriate for the command specified in the digital signature. If necessary it will verbally prompt and provide information to the user, and will decode infrared signals from a remote control. The results of interactions are transmitted by radio frequency spread spectrum to a cell cite, where they are then forwarded to the host computer. / Master of Science

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / Remote sensing satellites are typically low earth orbit, and often transmit the data gathered with the remote sensors to ground stations at locations on earth. These transmissions are band limited, and must operate within a 375 MHz bandwidth in the X-Band spectrum. This can present a limitation to the amount of data that can be transmitted during the short duration of a pass (typically less than 15 minutes). It is then highly desirable to increase the bandwidth efficiency of a system for data transmission in a remote sensing downlink. This paper describes a method of achieving higher efficiency by pre-programming the satellite to adjust the modulation and coding based in at least part on the slant range to the receiving ground station. The system uses variable coding and modulation to adjust to the slant range to the ground station to achieve a throughput increase of more than 50% of the data transferred during a pass using the currently accepted technology.

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / The aeronautical telemeter channel is characterized by Multipath interference, Doppler shift and rapid changes in channel behavior. In addition to transmission error during aeronautical telemeter, transmission losing also exists. In this paper, we investigate the correction of transmission error and processing of telemetry transmission losing, and propose an adaptive coding scheme, which organic combines Fountain code and low density parity check (LDPC) code. We call it fountain LDPC (FLDPC) coding. In the coding scheme, The LDPC code is explored to perform transmission error correction, while, the problem of transmission losing is resorted to fountain code. So FLDPC is robust for transmission losing and transmission error. Moreover, without knowing any of these the channel information, FLDPC can adapt the data link and avoid the interference through adjusting the transmission rate. Experimental results illustrated that a signification improvement in transmission reliability and transmitting efficiency can be achieved by using the FLDPC coding.

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