On the performance of a blind source separation based I/Q-corrector

I and Q Channel phase and gain mismatches are of great concern in communications receiver design. In this paper we carry out a detailed performance analysis of the Blind-Source Seperation (BSS) based imbalance compensation structure. The results indicate that the BSS structure can offer adequate performance for most communication systems. Since the compensation is carried out before any modulation specific processing, the proposed compensation method works with all standard modulation formats.

On the structure and performance of a novel blind source separation based carrier phase synchronization error compensator

In this paper we carry out a detailed performance analysis of a novel blind-source-seperation (BSS) based DSP algorithm that tackles the carrier phase synchronization error problem. The results indicate that the mismatch can be effectively compensated during the normal operation as well as in the rapidly changing environments. Since the compensation is carried out before any modulation specific processing, the proposed method works with all standard modulation formats and lends itself to efficient real-time custom integrated hardware or software implementations.

Sensory imagery in individuals who are blind and sighted: examining unimodal and multimodal forms

Introduction: Previous research has suggested that visual images are more easily generated, more vivid and more memorable than other sensory modalities. This research examined whether or not imagery is experienced in similar ways by people with and without sight. Specifically, the imabeability of visual, auditory and tactile cue words was compared. The degree to which images were multimodal or unimodal was also examined. Method: Twelve participants totally blind from early infancy and 12 sighted participants generated images in response to 53 sensory and non sensory words, rating imageability and the sensory modality, and describing images. From these 53 items, 4 subgroups of words, which stimulated images that were predominantly visual, tactile, auditory and low-imagery, respectively, were created. Results: T-tests comparing imageability ratings from blind and sighted participants found no differences for auditory and tactile words (both p>.1). Nevertheless, whilst participants without sight found auditory and tactile images equally imageable, sighted participants found images in response to tactile cue words harder to generate than visual cue words (mean difference: -0.51, p=.025). Participants with sight were also more likely to develop multisensory images than were participants without sight (both U≥15.0, N1=12, N2=12, p≤.008). Discussion: For both the blind and sighted, auditory and tactile images were rich and varied and similar language was used. Sighted participants were more likely to generate multimodal images. This was particularly the case for tactile words. Nevertheless, cue words that resulted in multisensory images were not necessarily rated as more imageable. The discussion considers whether or not multimodal imagery represent a method of compensating for impoverished unimodal imagery. Implications for Practitioners: Imagery is important not only as a mnemonic in memory rehabilitation, but also everyday uses for things such as autobiographical memory. This research emphasises both the importance of not only auditory and tactile sensory imagery, but also spatial imagery for people without sight.

Why is “blindsight” blind? A new perspective on primary visual cortex, recurrent activity and visual awareness

The neuropsychological phenomenon of blindsight has been taken to suggest that the primary visual cortex (V1) plays a unique role in visual awareness, and that extrastriate activation needs to be fed back to V1 in order for the content of that activation to be consciously perceived. The aim of this review is to evaluate this theoretical framework and to revisit its key tenets. Firstly, is blindsight truly a dissociation of awareness and visual detection? Secondly, is there sufficient evidence to rule out the possibility that the loss of awareness resulting from a V1 lesion simply reflects reduced extrastriate responsiveness, rather than a unique role of V1 in conscious experience? Evaluation of these arguments and the empirical evidence leads to the conclusion that the loss of phenomenal awareness in blindsight may not be due to feedback activity in V1 being the hallmark awareness. On the basis of existing literature, an alternative explanation of blindsight is proposed. In this view, visual awareness is a “global” cognitive function as its hallmark is the availability of information to a large number of perceptual and cognitive systems; this requires inter-areal long-range synchronous oscillatory activity. For these oscillations to arise, a specific temporal profile of neuronal activity is required, which is established through recurrent feedback activity involving V1 and the extrastriate cortex. When V1 is lesioned, the loss of recurrent activity prevents inter-areal networks on the basis of oscillatory activity. However, as limited amount of input can reach extrastriate cortex and some extrastriate neuronal selectivity is preserved, computations involving comparison of neural firing rates within a cortical area remain possible. This enables “local” read-out from specific brain regions, allowing for the detection and discrimination of basic visual attributes. Thus blindsight is blind due to lack of “global” long-range synchrony, and it functions via “local” neural readout from extrastriate areas.

Nutritional Evaluation and Optimisation in Neonates: a randomized, double-blind controlled trial of amino acid regimen and intravenous lipid composition in preterm parenteral nutrition

Background: Parenteral nutrition is central to the care of very immature infants. Current international recommendations favor higher amino acid intakes and fish oil–containing lipid emulsions. Objective: The aim of this trial was to compare 1) the effects of high [immediate recommended daily intake (Imm-RDI)] and low [incremental introduction of amino acids (Inc-AAs)] parenteral amino acid delivery within 24 h of birth on body composition and 2) the effect of a multicomponent lipid emulsion containing 30% soybean oil, 30% medium-chain triglycerides, 25% olive oil, and 15% fish oil (SMOF) with that of soybean oil (SO)-based lipid emulsion on intrahepatocellular lipid (IHCL) content. Design: We conducted a 2-by-2 factorial, double-blind, multicenter randomized controlled trial. Results: We randomly assigned 168 infants born at ,31 wk of gestation. We evaluated outcomes at term in 133 infants. There were no significant differences between Imm-RDI and Inc-AA groups for nonadipose mass [adjusted mean difference: 1.0 g (95% CI: 2108, 111 g; P = 0.98)] or between SMOF and SO groups for IHCL [adjusted mean SMOF:SO ratio: 1.1 (95% CI: 0.8, 1.6; P = 0.58]. SMOF does not affect IHCL content. There was a significant interaction (P = 0.05) between the 2 interventions for nonadipose mass. There were no significant interactions between group differences for either primary outcome measure after adjusting for additional confounders. Imm-RDI infants were more likely than Inc-AA infants to have blood urea nitrogen concentrations .7 mmol/L or .10 mmol/L, respectively (75% compared with 49%, P , 0.01; 49% compared with 18%, P , 0.01). Head circumference at term was smaller in the Imm-RDI group [mean difference: 20.8 cm (95% CI: 21.5, 20.1 cm; P = 0.02)]. There were no significant differences in any prespecified secondary outcomes, including adiposity, liver function tests, incidence of conjugated hyperbilirubinemia, weight, length, mortality, and brain volumes. Conclusion: Imm-RDI of parenteral amino acids does not benefit body composition or growth to term and may be harmful. This trial was registered at www.isrctn.com as ISRCTN29665319 and at eudract.ema.europa.eu as EudraCT 2009-016731-34.