170,295 research outputs found
Multilevel structured low-density parity-check codes for AWGN and Rayleigh channels
No full textWe propose a novel class of protograph low-density parity-check (LDPC) codes having a combinatorial rather than a random structure, which are termed multilevel-structured (MLS) LDPC codes. It is demonstrated that they posses a strikingly simple structure and, thus, benefit from reduced storage requirements, hardware-friendly implementations, and low-complexity encoding. Our simulation results provided for both additive white Gaussian noise (AWGN) and uncorrelated Rayleigh (UR) channels demonstrate that these advantages accrue without compromising the attainable bit error ratio (BER) and block error ratio (BLER) performance, when compared with their previously proposed more complex random-construction-based counterparts, as well as with other structured codes of the same length
Myths and Realities of Rateless Coding
No full textFixed-rate and rateless channel codes are generally treated separately in the related research literature and so, a novice in the field inevitably gets the impression that these channel codes are unrelated. By contrast, in this treatise, we endeavor to further develop a link between the traditional fixed-rate codes and the recently developed rateless codes by delving into their underlying attributes. This joint treatment is beneficial for two principal reasons. First, it facilitates the task of researchers and practitioners, who might be familiar with fixed-rate codes and would like to jump-start their understanding of the recently developed concepts in the rateless reality. Second, it provides grounds for extending the use of the well-understood code design tools — originally contrived for fixed-rate codes — to the realm of rateless codes. Indeed, these versatile tools proved to be vital in the design of diverse fixed-rate-coded communications systems, and thus our hope is that they will further elucidate the associated performance ramifications of the rateless coded schemes
Disinfection of dialysis monitors
No full textIn recent years the concept of biocompatibility is not limited to the dialytic membranes, but has been substituted by a more general viewpoint where all the parameters of the dialytic treatment are taken into consideration: the interaction of blood-surfaces (the dialyzer in all its components and the hematic lines), the sterilization of all materials, the quality of the solutions utilized for dialysis and reinfusion. Numerous studies have shown that the inflammatory response in dialysis is the cause of many of the side effects of dialytic treatment itself both acute and chronic. Hypoxemia, 'first use' syndrome, hypotension, allergic-anaphylactic reactions (short-term side effects); microinflammation, malnutrition, accelerated arteriosclerosis, anemia, beta(2) microglobulin amyloidosis, immunodeficiency, bone mass loss (long-term side effects), have all been reported. In this review, we will focus on the fluids utilized for hemodialysis (HD) and hemodiafiltration (HDF); we will describe the process of disinfection of the machines which produce the dialytic solutions. Copyright (c) 2007 S. Karger AG, Basel
Design of low-density parity-check codes: An overview
No full textThis article provides an overview of the conflicting design tradeoffs of low-density parity-check (LDPC) codes and thus advocates a more holistic approach to their design for wireless channels. We reveal some of the intricate interdependencies of the LDPC code parameters and hence recommend designing codes that strike an attractive tradeoff concerning a number of desirable attributes, rather than simply designing codes that closely approach capacity but possess less-attractive hardware implementations
Blood volume (Crit-Line) monitoring coupled with bioimpedance for the achievement of optimal dry body weight by hemofiltration in patients with cardiac heart failure (CHF)
No full textComparison of three different influenza vaccines in institutionalised elderly
No full textAbstract: The reactogenicity and the humoral immune response to three influenza vaccines were evaluated in a randomised, double-blind trial at nursing homes in north-east Italy in winter 1998-1999. Of the 285 subjects, who completed the follow-up, 93 were administered virosomal vaccine, 99 received MF59-adjuvanted vaccine and 93 had split vaccine. Ten subjects (0.3%) reported local and/or systemic reactions in the first week after immunisation. After 4 weeks, protection rates (greater than or equal to 40) were near 100% for the H1N1 and B strain and 76.0% against H3N2. The MF59-adjuvanted vaccine group had higher geometric mean titres than the other two. However, the true clinical benefit of the new adjuvanted vaccine should be further substantiated by comparative protective studies. Our results suggest that immune response to influenza vaccination in institutionalised elderly is satisfactory. (C) 2001 Elsevier Science Ltd. All rights reserved
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