No description available.

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With increasing bandwidth demand, DSL system continuously evolves to increase the maximum transmission frequency. However, the resulting cross-talk comes ever stronger and significantly degrades the system transmission performance. The cross-talk mainly comes from the DSLAM, modem, cable and splitter in a DSL system. This thesis proposes a signal cancellation method to overcome the cross-talk problem in a DSL splitter, which makes the DSL splitter no longer one of the cross-talk sources to affect the system transmission performance.

No description available.

Serotoninergic type 3 receptors (5HT3Rs) are members of the Cys-loop family of ligand-gated ion channels (LGIC), which includes nicotinic ACh, glycine, GABA-A and GABA-C receptors. All members of this family are widely expressed in the central and peripheral nervous systems, where they mostly participate in fast synaptic transmission. Activation of 5HT3Rs on vagal sensory nerve endings affect respiration, circulation, emesis and nociception; and in the central nervous system they are implicated in anxiety, depression, and drug dependence. In contrast, the function of 5HT3Rs in sympathetic neurons has not been fully determined. We discovered that 5HT3Rs interact with nicotinic acetylcholine receptors (nAChRs), the main drivers of the fast cholinergic autonomic synapse, through cross-talk mechanisms. We examined cross-talk by the patch-clamp technique on cultured mouse superior cervical ganglia (SCG) neurons. Co-stimulation of 5HT3Rs and nAChRs resulted in the generation of a combined current that was smaller than arithmetically predicted if the receptors did not interact with one another. This interaction, which we quantified as mean peak amplitude and mean ionic charge, was dependent on activation of 5HT3Rs and nAChRs, and independent of metabotropic receptors, Ca2+ entry and Ca2+ second messenger pathways, and of the direct action of 5HT on nAChRs. Preliminary data using an antibody targeted to the M3-M4 linker region of the 5HT3A subunit revealed that 5HT3Rs and nAChRs possibly cross-talk through physical interactions. These results revealed a potential role of the 5HT3R in the regulation of sympathetic synaptic transmission through cross-talk inhibition of nAChRs.

The Ras superfamily of GTPases are important regulators of morphogenesis involved in control of cytoskeletal dynamics, intracellular trafficking, apical-basal polarity and cell migration. Mis-regulation of GTPase signaling interferes with development and is linked to pathogenesis. Traditionally, GTPase signaling has been depicted as a series of independent linear pathways. However, recently it has become apparent that multiple GTPases can interact to regulate a single cellular process, functioning in poorly understood networks of cross talk between pathways during development. Jim Fristrom (unpublished data) identified a mutation (18-5) that interacts with components of the GTPases Rho1, Rala, and Cdc42 signaling in multiple developmental contexts. Genetic analysis, physical mapping studies, and sequencing of the mutant allele have indicated that the gene was an allele of GEFmeso (CG30115), which encodes guanine nucleotide exchange factor. To show that 18-5 is an allele of GEFmeso, I demonstrated that a GEFmeso transgene could functionally rescue developmental defects associated with the 18-5 mutation. I also investigated cross talk and network variation in signaling interactions between GEFmeso and other GTPase signaling components in the Drosophila wing. My data provide evidence for microenvironment-dependent variation in GTPase signaling networks in specific domains of the wing, and reveal intercellular variation in GTPase signaling within an otherwise uniform epithelium.

Yes / O-GlcNAcylation is an abundant post-translational modification in the nervous system, linked to both neurodevelopmental and neurodegenerative disease. However, the mechanistic links between these phenotypes and site-specific O-GlcNAcylation remain largely unexplored. Here, we show that Ser517 O-GlcNAcylation of the microtubule-binding protein Collapsin Response Mediator Protein-2 (CRMP2) increases with age. By generating and characterizing a Crmp2S517A knock-in mouse model, we demonstrate that loss of O-GlcNAcylation leads to a small decrease in body weight and mild memory impairment, suggesting that Ser517 O-GlcNAcylation has a small but detectable impact on mouse physiology and cognitive function. / a Wellcome Trust Senior Research Fellowship (WT087590MA) to D.M.F.v.A., an ARUK Pilot Project grant to R.W., and support from Tenovus Scotland to V.M. The phosphoproteomics mass spectrometry work was supported by the Horizon 2020 program INFRAIA project Epic-XS (project 823839) to A.J.R.H.

Twisted pan (structured wire) cabling is a principal component in the communications infrastructure, with millions of meters being installed weekly. The rate of increase in upper frequency for this cable appears to be doubling approximately every two years. Clearly, a rigorous approach to the design of these cables is fundamental to achieving data transmission at these frequencies with increasingly stringent performance requirements. This thesis derives a family of equations for the secondary parameters based on an explicit relationship between cable dimensions and materials. These equations have been validated against experimental results and fOWld accurate. Further. equations are developed which calculate the overall S-parameters for cascaded multi.pair cables, the return loss and cross-talk between transmission charmels. In tenns of cable specification. the secondary parameters are the most significant with many of the perfonnance criteria based on these. With designs based largely on the manipulation of physical dimensions, there has been no family of secondary parameter equations given explicitly as functions of cable dimensions and material properties. Similarly, tools have not existed to allow the investigation of design variability or the effects of handling and installation. These are principal requirements in the cable design process. A modelling package, based on Transmission-Line Matrix (TLM) modelling, is developed to a1low the investigation of manufacturing variability and installation handling effects on overall perfonnance of a cable. This modelling technique is validated against both experimental results and analytical results the comparison is excellent. Finally a novel method for the calculation of cross talk between cable pairs is presented. This method is based on a hybrid field·circuit model. Comparisons with measurements show good agreement.

Activity of skeletal muscles produce electrical signals that can be measured using electrodes placed on the skin surface over a target muscle or with electrodes inserted into the muscle. Such electromyographic (EMG) signals provide fundamental information about the intensity of the neural drive acting upon muscle. In addition, EMG signals are widely deployed as control sources for powered prosthetic limbs. One limitation related to recording EMG signals, however, is that signals arising from neighboring muscles may contribute significantly to the activity detected with electrodes placed over or within a given target muscle. Such unwanted contribution of signal from muscles other than the targeted muscle is referred to as cross-talk. Cross-talk was investigated in four neighboring muscles in the forearm with different electrode types and configurations: bipolar intramuscular, monopolar intramuscular, and bipolar surface EMG. Cross-correlation analysis was performed for every pairwise combination of EMG signal recorded. The peak correlation coefficient at near-zero time delay provided an index of the degree of cross-talk. Correlation coefficients dropped off exponentially with distance between recording electrodes. Bipolar intramuscular EMG had the narrowest pick-up range, with a length constant of 14.5 mm. Bipolar surface EMG had a longer length constant of 37.0 mm, whereas monopolar intramuscular EMG had the longest length constant of 64.5 mm. A second set of experiments indicated that correlation in EMG signals detected in different muscles was unlikely to have a neural basis. Therefore, because of their wide detection range, monopolar configurations including those involving intramuscular electrodes, should be avoided.

New methodology has been utilized to provoke or increase targeted metabolic pathways in microbes. The low hanging fruit of natural products has been discovered over the last 50 years. To continue finding new metabolites to be used as possible drug candidates, methodology development such as those proposed herein are necessary. This methodology uses extracts from known pathogenic bacteria to elicit production of latent biosynthetic pathways from environmental bacterial isolates that may be active against the original pathogenic strains. A new compound, MAV-1 (1) of the diketopiperazine family (Figure 1) was isolated and identified utilizing these techniques. The structure of MAV-1 (1) was defined by a combination of mass spectroscopy (MS) and nuclear magnetic resonance (NMR) spectroscopy. Discovery of MAV-1 (1), a possible precursor to other known compounds, demonstrates the continuing utility of microbial sources with new chemodiversity.