3,221 research outputs found

    A robust M-estimate adaptive equaliser for impulse noise suppression

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    In this paper, a FIR adaptive equaliser for impulse noise suppression is proposed. It is based on the minimization of an M-estimate objective function which has the ability to ignore or down-weight a large error signal when it exceeds certain thresholds. An advantage of the proposed method is that its solution is governed by a system of linear equations, called the M-estimate normal equation. Therefore, traditional fast algorithms like the recursive least squares algorithm can be applied. Using a robust estimation of the thresholds and the recursive least square algorithm, an M-estimate RLS (M-RLS) algorithm is developed. Simulation results show that the proposed algorithm has better convergence performance than the N-RLS and MN-LMS algorithms when the input signal of the equaliser is corrupted by individually or consecutive impulse noises. It also shares the low steady state error of the traditional RLS algorithm.published_or_final_versio

    A family of spread-sequences for CDMA system in a multipath fading channel

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    A new class of orthogonal code-division multiple access (CDMA) system is developed. The key characteristic of the system is that the data symbols are spreaded by a spread-sequence that is longer than the period of the symbol and hence overlapped with the neighboring symbols. Using this approach, temporal diversity is incorporated with other diversities. Due to the temporal diversity, the proposed CDMA system performs well in a fading environment. In this paper, a method for designing such a spread-sequence using filter bank theory is presented. The length of the spread-sequence could be varied according to the requirement. Simulation results show that the proposed spread-sequence based system yields lower BER than the conventional Gold codes based DS/CDMA system.published_or_final_versio

    Long non-coding RNA deregulation in tongue squamous cell carcinoma

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    Background. The deregulated tumorigenic long non-coding RNA (lncRNA) has been reported in several malignancies. However, there is still no comprehensive study on tongue squamous cell carcinoma (SCC). Methods. Functional reannotation for the human lncRNA was carried out by ncFANs. Real-time quantitative PCR was used to validate the identified lncRNAs. Results. Using the functional annotation algorithm from ncFANs, 8 differentially expressed lncRNAs were identified. Lnc-PPP2R4-5, lnc-SPRR2D-1, lnc-MAN1A2-1, lnc-FAM46A-1, lnc-MBL2-4:1, and lnc-MBL2-4:3 were upregulated in the microdissected tongue SCC tissues. In comparison, lnc-AL355149.1-1 and lnc-STXBP5-1 showed significant downregulation. High level of lnc-MBL2-4:3 was significantly associated with the node positive tongue SCC patients. Further, patients with advanced T-stage demonstrated a further reduction of lnc-AL355149.1-1 in the tumor tissues. Treatment of tongue SCC cells with 5-fluorouracil and paclitaxel can reserve the expression patterns observed in the tongue SCC tissues. Further, changes of lnc-MBL2-4:3 and lnc-AL355149.1-1 expression levels were noticed in the cisplatin-resistant tongue SCC cells. Conclusions. Our results demonstrated that functional reannotation allows us to identify novel lncRNAs using the existing gene expression array dataset. The association of lncRNA with the T-stage and nodal status of tongue SCC patients suggested that lncRNA deregulation was involved in the pathogenesis of tongue SCC.published_or_final_versio

    Differential expression of long noncoding RNA in primary and recurrent nasopharyngeal carcinoma

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    Background. Recent studies suggested that non-protein-coding genes are implicated in the tumorigenic process of nasopharyngeal carcinoma (NPC). In the present study, we aimed to identify the differentially expressed long noncoding RNA (lncRNA) using data available in the public domain. Methods. Microarray data set GSE12452 was reannotated with ncFANs. Real-time quantitative PCR was used to quantify and validate the identified lncRNAs in NPC. Results. In primary NPC, upregulation of lnc-C22orf32-1, lnc-AL355149.1-1, and lnc-ZNF674-1 was observed. High levels of lnc-C22orf32-1 and lnc-AL355149.1-1 were significantly associated with the male patients. In addition, increased expression of lnc-C22orf32-1 and lnc-ZNF674-1 was associated with advanced tumor stages. Recurrent NPC displayed a distinctive lncRNA expression pattern. lnc-BCL2L11-3 was significantly increased in the recurrent NPC tissues. In addition, significant reduction of lnc-AL355149.1-1 and lnc-ZNF674-1 was observed in the recurrent NPC tissues. Conclusions. Our results demonstrated that it is feasible to identify the differentially expressed lncRNA in the microarray dataset by functional reannotation. The association of lncRNA with gender and tumor size implicated that lncRNA possibly plays a part in the pathogenesis of primary NPC. Further, the distinctive lncRNA identified in the recurrent NPC may reveal a distinctive development mechanism underlying tumor recurrence. © 2014 Wei Gao et al.published_or_final_versio

    A perceptual based rate control scheme for MPEG-2

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    In this paper, a new perceptual based rate control algorithm for MPEG-2 is presented. The algorithm first determines the target bit count for each frame using simple statistical models. Precise bit allocation is used to adjust the macroblock quantization scale factors to meet the given bit count, with the uniform visual fidelity as the primary objective. Since the buffer is very stable, it is less sensitive to transmission delay, Experimental results showed that it gave better visual quality and less buffer variations as compared to the TM5 rate control scheme.published_or_final_versio

    Buffer control algorithm for low bit-rate video compression

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    In this paper, a new buffer control algorithm for motion-compensated hybrid DPCM/DCT coding (like H.261 and MPEG-1 I pictures) is presented. The algorithm uses the bit allocation algorithm to determine the quantization scale factor of each macroblock under a given target bit rate. An important advantage of the algorithm is that it has precise control of the buffer and avoids buffer overflow events which is a severe problem in low bit rate video coder. Furthermore, the coder is able to allocate bits to the picture as a whole, resulting in better rate-distortion trade-off. Simulation results show that the H.261 coder, using the proposed algorithm, can achieve a higher PSNR and better visual quality than codec using conventional buffer control algorithm.published_or_final_versio

    Least mean M -estimate algorithms for robust adaptive filtering in impulse noise

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    This paper proposes two gradient-based adaptive algorithms, called the least mean M-estimate and the transform domain least mean M -estimate (TLMM) algorithms, for robust adaptive filtering in impulse noise. A robust M -estimator is used as the objective function to suppress the adverse effects of impulse noise on the filter weights. They have a computational complexity of order O(N) and can be viewed, respectively, as the generalization of the least mean square and the transform-domain least mean square algorithms. A robust method for estimating the required thresholds in the M -estimator is also given. Simulation results show that the TLMM algorithm, in particular, is more robust and effective than other commonly used algorithms in suppressing the adverse effects of the impulses. © 2000 IEEE.published_or_final_versio

    An adaptive multiresolution modification of the H.263 video coding algorithm

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    An adaptive multiresolution approach for video coding is presented. The algorithm uses the information content to determine the resolution of the video to be encoded. An important advantage of the algorithm is that the codec can maintain a very stable frame rate with reasonable image quality during scene change and provide better quality video when the motion is less rapid. Simulation results show that the modified H.263 coder, using the proposed algorithm, can maintaining better image quality and a more steady frame rate than the TMN 5 algorithm at low bit-rate.published_or_final_versio

    Minimally invasive treatment of oligometastasis in the liver in recurrent nasopharyngeal carcinoma

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