Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.Comment: To appear in the IEEE Transactions on Signal Processin

The Lift Pool Method for Isolation of cDNA Clones from Lambda Phage Libraries

A PCR based strategy was developed to screen a Xenopus oocyte λgt10 cDNA library. The PCR-based lift pool (LP) method follows the same two tiered strategy as conventional screening of phage libraries by filter hybridization. Two rounds of plating, one at high density to detect the clone, and one at low density to purify the clone to homogeneity, are performed. In the first round, lysates from high density plates, termed plate pools (PP), serve as template for PCR. In the second round, phage particles adhering to plaque lifts of low density plates are washed off nitrocellulose filters to create LPs, which are used as template for PCR. The integrity of the plaques on the low-density plates is preserved. Once a positive LP has been identified, plaques on the corresponding plate are screened individually by PCR. Using isoform specific primer pairs for Xenopus myosin 7a and myosin 1d, two lambda clones were isolated. Subsequent DNA sequence analysis confirmed their identities as myosin isoforms (GenBank accession numbers: DQ100353 and AF540952). This method offers a time saving, cost-effective alternative to other hierarchical pooling strategies for the repeated screening by PCR of an arrayed lambda phage library

Complete analysis of the B-cell response to a protein antigen, from in vivo germinal centre formation to 3-D modelling of affinity maturation

Somatic hypermutation of immunoglobulin variable region genes occurs within germinal centres (GCs) and is the process responsible for affinity maturation of antibodies during an immune response. Previous studies have focused almost exclusively on the immune response to haptens, which may be unrepresentative of epitopes on protein antigens. In this study, we have exploited a model system that uses transgenic B and CD4<sup>+</sup> T cells specific for hen egg lysozyme (HEL) and a chicken ovalbumin peptide, respectively, to investigate a tightly synchronized immune response to protein antigens of widely differing affinities, thus allowing us to track many facets of the development of an antibody response at the antigen-specific B cell level in an integrated system <i>in</i> <i>vivo</i>. Somatic hypermutation of immunoglobulin variable genes was analysed in clones of transgenic B cells proliferating in individual GCs in response to HEL or the cross-reactive low-affinity antigen, duck egg lysozyme (DEL). Molecular modelling of the antibody–antigen interface demonstrates that recurring mutations in the antigen-binding site, selected in GCs, enhance interactions of the antibody with DEL. The effects of these mutations on affinity maturation are demonstrated by a shift of transgenic serum antibodies towards higher affinity for DEL in DEL-cOVA immunized mice. The results show that B cells with high affinity antigen receptors can revise their specificity by somatic hypermutation and antigen selection in response to a low-affinity, cross-reactive antigen. These observations shed further light on the nature of the immune response to pathogens and autoimmunity and demonstrate the utility of this novel model for studies of the mechanisms of somatic hypermutation

Elevated protein concentrations in newborn blood and the risks of autism spectrum disorder, and of social impairment, at age 10 years among infants born before the 28th week of gestation

Among the 1 of 10 children who are born preterm annually in the United States, 6% are born before the third trimester. Among children who survive birth before the 28th week of gestation, the risks of autism spectrum disorder (ASD) and non-autistic social impairment are severalfold higher than in the general population. We examined the relationship between top quartile inflammation-related protein concentrations among children born extremely preterm and ASD or, separately, a high score on the Social Responsiveness Scale (SRS total score ≥65) among those who did not meet ASD criteria, using information only from the subset of children whose DAS-II verbal or non-verbal IQ was ≥70, who were assessed for ASD, and who had proteins measured in blood collected on ≥2 days (N = 763). ASD (N = 36) assessed at age 10 years is associated with recurrent top quartile concentrations of inflammation-related proteins during the first post-natal month (e.g., SAA odds ratio (OR); 95% confidence interval (CI): 2.5; 1.2–5.3) and IL-6 (OR; 95% CI: 2.6; 1.03–6.4)). Top quartile concentrations of neurotrophic proteins appear to moderate the increased risk of ASD associated with repeated top quartile concentrations of inflammation-related proteins. High (top quartile) concentrations of SAA are associated with elevated risk of ASD (2.8; 1.2–6.7) when Ang-1 concentrations are below the top quartile, but not when Ang-1 concentrations are high (1.3; 0.3–5.8). Similarly, high concentrations of TNF-α are associated with heightened risk of SRS-defined social impairment (N = 130) (2.0; 1.1–3.8) when ANG-1 concentrations are not high, but not when ANG-1 concentrations are elevated (0.5; 0.1–4.2)

Radio resource allocation and multiuser detection in very large scale wireless multiple access networks

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Reconsidering reviews: the role of scoping reviews in digital medicine and pediatrics

Digital health is a rapidly developing field which is positioned to transform the manner in which healthcare is delivered, especially amongst adolescents and young adults. In order to assess the efficacy of novel medical devices, clinicians and researchers often turn to the literature for guidance. Randomized control trials and the systematic reviews and meta-analyses that they inform are considered to be at the top of the evidence hierarchy. While they are excellent tools to identify and to summarize the best available evidence to answer a specific research question, they are poorly equipped to provide a more expansive understanding of the body of relevant literature in a timely manner. In this letter we discuss the utility of the scoping review, an underutilized style of academic writing designed to map key concepts in a body of literature. This method is ideal when reporting on the fast-paced field of digital medicine, as it allows for rapid synthesis of the available literature

Intracolonic administration of zileuton, a selective 5-lipoxygenase inhibitor, accelerates healing in a rat model of chronic colitis

BACKGROUND: 5-Lipoxygenase products play a part in inflammatory response. AIMS: The effect of intracolonic administration of zileuton (a 5-lipoxygenase inhibitor) on colonic damage and eicosanoid local release was assessed in a rat model of colitis. METHODS: Ninety rats with trinitrobenzenesulphonic acid induced colitis were randomised to receive placebo, 5-aminosalicylic acid (50 mg/kg), or zileuton (50 mg/kg) intracolonically for four weeks. Local eicosanoid release was monitored by intracolonic dialysis throughout the study. The colon was removed for macroscopic and histological assessment at weeks 1, 2, and 4 after colitis induction in 10 rats of each group. RESULTS: Zileuton significantly reduced macroscopic damage score after four weeks of treatment in comparison with the other two groups (p = 0.034). In addition, zileuton administration significantly increased the intracolonic release of both thromboxane B2 at week 1 (p = 0.05) and prostaglandin E2 at weeks 2 and 4 (p < 0.05). Zileuton and 5-aminosalicylic acid decreased leukotriene B4 release by 90% at day 3. CONCLUSIONS: Intracolonic zileuton, compared with 5-aminosalicylic acid and placebo, seems to improve the course of the disease in a model of chronic colitis. This effect may be related to an increased and maintained production of prostaglandin E2 together with inhibition of leukotriene B4 synthesis