Turbo soft combining hybrid ARQ techniques: Theory and application to 3G wireless networks

This paper deals with the application of Hybrid Automatic Repeat reQuest (h-arq) techniques to allow reliable data communications in wireless 3G networks. Basically, retransmission of coded data is endowed with soft combining schemes applied, respectively, to packet replicas, or to decoding algorithm outputs. In particular, the proposed coding scheme takes advantage of error correction capabilities of the turbo codes, while the combining algorithm follows the diversity approach. The performance of the proposedh-arq schemes has been derived by means of a suitable analytical approach and numerical simulations in the case of a typical umts environment. The results highlight the good behavior of the proposed scheme in term of error rate, throughput, packet delivery delay and power reduction.     

Central and peripheral influences on retention of postural asymmetry in rats.

Four studies with 94 Long-Evans rats examined potential neural processes involved in retention of a peripherally induced postural asymmetry. In Exp I, dorsal and ventral spinal root section following varying intervals of stimulation successfully abolished peripherally induced hindlimb asymmetry. Exp II revealed that 50 min of ventral root stimulation, in the absence of central connection, was not effective in producing asymmetry persistence. Exp III attempted to more closely delineate the time parameters involved in peripherally induced asymmetry retention. Asymmetry was found to consistently outlast a spinal transection if 40 min of stimulation was given. In Exp IV, possible modulatory higher brain center influences on the retention processes were demonstrated. Asymmetry persistence was consistently observed in Ss that received 10, 20, 30, 40, or 50 min of hindlimb stimulation if 50 min were allowed to elapse between the onset of stimulation and spinal section. Results (1) suggest an active involvement of spinal reflex centers in the fixation process, (2) indicate that the manner in which reflex activity is altered is not crucial as long as underlying time parameters are adhered to, and (3) demonstrate that higher center influences can modulate retention of a postural asymmetry in a complex manner. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The intact isolated (ex vivo) retina as a model system for the study of excitotoxicity

Excitotoxicity is defined as a mode of neural cell death triggered by overactivation of receptors for the amino acid transmitter glutamate. There is considerable evidence that excitotoxicity is responsible for cell death in several neuropathological states, including some retinal diseases. The isolated retina, particularly from chick embryos, has been used extensively as an experimental system to characterize this process. This paper summarizes the use of isolated retina as a model system for studies of excitotoxicity from a theoretical and methodological point of view, and reviews results obtained from studies utilizing this system.     

Occurrence of biogenic amine-forming lactic acid bacteria in wine and cider

A collection of 810 lactic acid bacteria (LAB) strains isolated from wine and cider was screened for potential biogenic amine (BA) producers by combining molecular and phenotypic approaches. A newly developed multiplex PCR method allowed for the simultaneous detection of four genes involved in the production of histamine (histidine decarboxylase, hdc), tyramine (tyrosine decarboxylase, tyrdc) and putrescine (via either ornithine decarboxylase, odc, or agmatine deiminase, agdi) while TLC and HPLC analysis allowed for BA-production determination. One hundred and fifty-eight LAB strains were monitored by the molecular/phenotypic double approach and revealed a good correlation between genotypic and phenotypic data. Eighteen per cent of the tested strains were positive for at least one BA target gene with up to three detected simultaneously, in particular amongst Lactobacillus brevis and Lactobacillus hilgardii isolates for the tyrdc and agdi genes. The most frequent gene corresponded to the agdi gene detected in 112 strains (14% of all LAB strains) of 10 different LAB species. The tyrdc gene was detected in 67 strains represented by 7 different LAB species (8% overall), especially those isolated from wine. Lower levels of hdc⁺ (2% of strains) and especially odc⁺ (0.5% of strains) strains were observed. Interestingly, species that have never been described to carry BA-producing pathway genes were identified in this study. Furthermore, only one cadaverine-producer was detected and corresponded to Lactobacillus 30a, a collection strain not found in fermented beverages, although cadaverine is commonly detected in wines.     

Analysis and comparison of scheduling techniques for a BWA OFDMA mobile system

In the last few years the wireless metropolitan area networks (WMANs) have increased their popularity and attracted the interest of important research groups all over the world; as a consequence, several standards have been proposed. Among them, the IEEE 802.16 (WiMAX) is one of the most promising standard to carry out a full‐service broadband wireless network in an urban and suburban area. This standard provides high data rate within a wide coverage area with low implementation costs, possibility of multi‐traffic communications, and different network topologies. This paper deals with the analysis and performance comparison of different scheduling techniques for WiMAX networks for allowing quality of service (QoS) differentiation when different types of applications have to be supported and achieving a fair distribution of resource among users. In particular, the focus here is on the resource allocation problem for the case of mobile stations (MSs) active in an urban environment. The proposed scheduling algorithms exploit the orthogonal frequency division multiple access (OFDMA) scheme with adaptive modulation techniques in order to achieve a better network behavior. The performance of the proposed approaches will be derived here by means of theoretical analysis and computer simulations. Copyright © 2009 John Wiley & Sons, Ltd.     

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Two detoxification mechanisms working in the marine diatom Thalassiosira weissflogii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl₂ concentrations. T. weissflogii cells responded by synthesizing metal-binding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that glutathione could also be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P < 0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.     

Elevated Circulating and Placental SPINT2 Is Associated with Placental Dysfunction

Biomarkers for placental dysfunction are currently lacking. We recently identified SPINT1 as a novel biomarker; SPINT2 is a functionally related placental protease inhibitor. This study aimed to characterise SPINT2 expression in placental insufficiency. Circulating SPINT2 was assessed in three prospective cohorts, collected at the following: (1) term delivery (n = 227), (2) 36 weeks (n = 364), and (3) 24–34 weeks’ (n = 294) gestation. SPINT2 was also measured in the plasma and placentas of women with established placental disease at preterm (<34 weeks) delivery. Using first-trimester human trophoblast stem cells, SPINT2 expression was assessed in hypoxia/normoxia (1% vs. 8% O2), and following inflammatory cytokine treatment (TNFα, IL-6). Placental SPINT2 mRNA was measured in a rat model of late-gestational foetal growth restriction. At 36 weeks, circulating SPINT2 was elevated in patients who later developed preeclampsia (p = 0.028; median = 2233 pg/mL vs. controls, median = 1644 pg/mL), or delivered a small-for-gestational-age infant (p = 0.002; median = 2109 pg/mL vs. controls, median = 1614 pg/mL). SPINT2 was elevated in the placentas of patients who required delivery for preterm preeclampsia (p = 0.025). Though inflammatory cytokines had no effect, hypoxia increased SPINT2 in cytotrophoblast stem cells, and its expression was elevated in the placental labyrinth of growth-restricted rats. These findings suggest elevated SPINT2 is associated with placental insufficiency.     

3D‐Printing of High‐κ Thiol‐Ene Resins with Spiro‐Orthoesters as Anti‐Shrinkage Additive

Tri(ethylene glycol) divinyl ether and the spiro‐orthoester 2‐((allyloxy)methy)‐1,4,6‐trioxospiro[4.4]nonane can be formulated in different ratios and crosslinked by thiol‐ene reactions. The spiro‐orthoester is used as anti‐shrinkage additive, enabling shrinkage reduction of up to 39%. Addition of a radical photoinitiator for the thiol‐ene reaction and a cationic photoinitiator for the double ring‐opening of the spiro‐orthoester enables dual‐curing for application in 3D‐printing. The formulation free of the spiro‐orthoester shows gelation during the printing process and, correspondingly, low resolution. The formulations containing the spiro‐orthoester exhibit higher resolutions in the range of 50 µm. The resins containing mixtures of tri(ethylene glycol) divinyl ether and the spiro‐orthoester show permittivities as high as 10⁴. The dielectric loss factor of the resins is in the range of 0.5–7.6, and the conductivity in the range of 1.3?10^?11 to 2.0?10^?11 S cm^?1. These high‐κ materials can be 3D‐printed by digital light processing for the next generation of electronic materials.     

Bioleaching of metal from waste stream using a native strain of Acidithiobacillus isolated from a coal mine drainage

In this study, the feasibility of using a biohydrometallurgical technique for selective metals recovery from electronic waste (e‐waste) by bacterial bioleaching was investigated. Acidithiobacillus was identified in coal mining acid mine drainage (AMD). The microorganism was studied using specific sequencing of a 16s rDNA fragment. The potential for the dissolution of copper from waste printed wire boards (PWBs) using the isolated Acidithiobacillus ferrooxidans (A. ferroxidans) was evaluated. The bioleaching experiments were performed in an orbital shaker at 30 °C and 170 rpm, with 10 % (v/v) inoculum and a pulp density of 30 g/L. The copper concentration was determined by energy dispersive x‐ray fluorescence (XRF). The result shows that copper recovery from PWBs using our A. ferrooxidans strain was 95 % after 8 days, which showed the feasibility of this process.