40 research outputs found

    Robust vector quantization for noisy channels

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    The paper briefly discusses techniques for making vector quantizers more tolerant to tranmsission errors. Two algorithms are presented for obtaining an efficient binary word assignment to the vector quantizer codewords without increasing the transmission rate. It is shown that about 4.5 dB gain over random assignment can be achieved with these algorithms. It is also proposed to reduce the effects of error propagation in vector-predictive quantizers by appropriately constraining the response of the predictive loop. The constrained system is shown to have about 4 dB of SNR gain over an unconstrained system in a noisy channel, with a small loss of clean-channel performance

    An anti-TNF--Ī± antibody mimetic to treat ocular inflammation

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    Infliximab is an antibody that neutralizes TNF-Ī± and is used principally by systemic administration to treat many inflammatory disorders. We prepared the antibody mimetic Fab-PEG-Fab (FpFinfliximab) for direct intravitreal injection to assess whether such formulations have biological activity and potential utility for ocular use. FpFinfliximab was designed to address side effects caused by antibody degradation and the presence of the Fc region. Surface plasmon resonance analysis indicated that infliximab and FpFinfliximab maintained binding affinity for both human and murine recombinant TNF-Ī±. No Fc mediated RPE cellular uptake was observed for FpFinfliximab. Both Infliximab and FpFinfliximab suppressed ocular inflammation by reducing the number of CD45+ infiltrate cells in the EAU mice model after a single intravitreal injection at the onset of peak disease. These results offer an opportunity to develop and formulate for ocular use, FpF molecules designed for single and potentially multiple targets using bi-specific FpFs

    A Simple and Effective Precoding Scheme for Noise Whitening on Intersymbol Interference Channels

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    A precoding scheme for noise whitening on intersymbol interference channels is presented. This scheme is compatible with trellis-coded modulation and unlike Tomlinson precoding allows constellation shaping. It can be used with almost any shaping scheme (including the optimal SVQ shaping) as opposed to trellis precoding which can only be used with trellis shaping. The implementation complexity of this scheme is minimal - only three times that of the noise prediction filter, and hence effective noise whitening can be achieved by using a high-order predictor

    On SVQ Shaping of Multidimensional Constellations - High-Rate Large-Dimensional Constellations

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    An optimal shaping scheme for multidimensional constellations, motivated by some ideas from a fixed-rate structured vector quantizer (SVQ), was recently proposed by Laroia. It was shown that optimal shaping could be performed subject to a constraint on the CER2 or PAR2 by expressing the (optimally shaped) constellation as the codebook of an SVQ and using the SVQ encoding/decoding algorithms to index the constellation points. Further, compatibility with trellis coded modulation was demonstrated. The complexity of the proposed scheme was reasonable but dependent on the data transmission rate. In this paper, we use recent results due to Calderbank and Ozarow to show that complexity of this scheme can be reduced and made independent of the data rate with essentially no effect on the shaping gain. Also, we modify the SVQ encoding/decoding algorithms to reduce the implementation complexity even further. It is shown that SVQ shaping can achieve a shaping gain of about 1.20 dB with a PAR2 of 3.75 at a very reasonable complexity (about 15 multiply-adds/baud and a memory requirement of 1.5 kbytes). Further, a shaping gain of 1 dB results in a PAR2 of less than 3. This is considerable less than a PAR2 of 3.75 for Forney's trellis shaping scheme that gives about 1 dB shaping gain

    Robust vector quantisation by transmission energy allocation

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    Vision-related Quality of Life After Bilateral Implantation of Monofocal and Multifocal Intraocular Lenses

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    Purpose: To evaluate vision-related quality of life in two sets of patients after routine Cataract surgery implanting with traditional versus multifocal intraocular lens (IOLs). Methods: In a cross-sectional prospective study, 58 and 33 candidates for Cataract surgery were divided into traditional (Acrysof SN60WF, Alcon Laboratories, Inc) and multifocal IOL (AcrySof IQ PanOptix IOL TFNT00, Alcon Laboratories, Inc.) groups, respectively. The primary outcome was VFQ-25 scores. The secondary outcomes were making comparisons between the two IOL types in the near vision and the driving items. Results: The mean patients' age in traditional and multifocal IOL groups was 60.85 Ā± 7.40 (55% female) and 59.85 Ā± 8.95 (36% female) years, respectively. The mean VFQ-25 total scores in traditional and multifocal IOL groups before and after surgery were 63.69 Ā± 4.95 and 72.15 Ā± 9.66, and 98.08 Ā± 0.70 and 95.70 Ā± 1.30, respectively (P = 0.001 & 0.001). The mean scores of night driving in traditional and multifocal IOL groups were 38.79 Ā± 20.50 and 44.35 Ā± 21.12 (P = 0.1) before surgery which improved to 97.41 Ā± 7.68 and 56.45 Ā± 11.12 after surgery, respectively (P = 0.001). The mean scores of near vision in traditional and multifocal IOL groups were 46.83 Ā± 10.56 and 50.53 Ā± 8.58 (P = 0.2) before surgery which improved to 89.94 Ā± 4.87 and 100.00 Ā± 0.00 after surgery, respectively (P = 0.001). Conclusion: Vision-related quality of life after Cataract surgery with either type of traditional or multifocal (PanOptix) IOLs improved to an excellent level. Traditional IOLs provided more satisfaction in nighttime driving while multifocal IOLs provided increased satisfaction in near and intermediate vision

    Source-Dependent Channel Coding and its Application to CELP

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