On the performance of densified DVB-H single frequency networks

The broadcasting of TV programmes to mobile phones can be enabled by the newly developed technology called Digital Video Broadcasting-Handheld (DVB-H). Because of the scarcity and cost of frequency resources, frequency reuse needs to be considered when rolling out DVB-H networks. By simulcasting the same content from several transmitters, a Single Frequency Network (SFN) can provide good coverage and good frequency efficiency. In this paper, the performance of densified DVB-H SFN networks is analysed in terms of the coverage probability under different coverage requirements with and without frequency reuse. A dichotomy searching approach is used to determine the optimal cell radius for a cell in a densified DVB-H SFN for a given network topology. Based on the optimal cell radius map and a SFN gain map generated from the simulation results, guidelines are proposed on how to avoid the potential pitfalls in configuring the parameters of a densified DVB-H SFN network and optimise its parameters in terms of minimising the cost of the network for a range of predefined network parameters

Cross-spectral analysis of the X-ray variability of Mrk 421

Using the cross-spectral method, we confirm the existence of the X-ray hard lags discovered with cross-correlation function technique during a large flare of Mrk 421 observed with BeppoSAX . For the 0.1--2 versus 2--10keV light curves, both methods suggest sub-hour hard lags. In the time domain, the degree of hard lag, i.e., the amplitude of the 3.2--10 keV photons lagging the lower energy ones, tends to increase with the decreasing energy. In the Fourier frequency domain, by investigating the cross-spectra of the 0.1--2/2--10 keV and the 2--3.2/3.2--10 keV pairs of light curves, the flare also shows hard lags at the lowest frequencies. However, with the present data, it is impossible to constrain the dependence of the lags on frequencies even though the detailed simulations demonstrate that the hard lags at the lowest frequencies probed by the flare are not an artifact of sparse sampling, Poisson and red noise. As a possible interpretation, the implication of the hard lags is discussed in the context of the interplay between the (diffusive) acceleration and synchrotron cooling of relativistic electrons responsible for the observed X-ray emission. The energy-dependent hard lags are in agreement with the expectation of an energy-dependent acceleration timescale. The inferred magnetic field (B ~ 0.11 Gauss) is consistent with the value inferred from the Spectral Energy Distributions of the source. Future investigations with higher quality data that whether or not the time lags are energy-/frequency-dependent will provide a new constraint on the current models of the TeV blazars.Comment: 11 pages, 6 figures, accepted by MNRA

Effect of metal ions on the growth and metabolites production of Ganoderma lucidum in submerged culture

The effects of several metal ions on the cell growth, production of polysaccharides by Ganoderma lucidum in submerged fermentation were studied. The results showed that 50 ppm Se2+ and 25 ppm Se2+ was identified to be the most favorable for biomass (11.103 ± 0.6 g/l ) and polysaccharide production (IPS and EPS was 183 ± 10.2 and 248 ± 5.5 mg/l, respectively); 100 ppm of Fe2+ and 50 ppm of Zn2+ were suitable for growth (the biomass was 8.23 ± 0.67 and 8.01 ± 0.29 g/l, respectively) and under the concentration of 50 ppm of Zn2+ and Fe2+, the production of polysaccharide was up to the most (EPS content: 263±4 and 254.3±8.0 mg/l; IPS content : 170±0.8 and 174±5 mg/l); Mg2+ had no obvious effect on biomass and polysaccharide production; Cr2+ was poisonous to the cell under the test concentration. The combination (FeSO4, 50 ppm; NaSeSO3, 25 ppm; ZnSO4, 75 ppm) by A 9 ×3 replicates (27) experiments of L9 (34) orthogonal projects was tested optimal for the cell growth and polysaccharides production. Biomass, EPS and IPS production reached their good value of 14.7 ± 0.5 g/l, 369 ± 6 mg/l and 239 ± 4 mg/g, respectively under the combination, which were higher 130.7, 50 and 50%, respectively than in the basal fermentation medium without metal ions. The validation experiment showed the experimental values agreed with the predicted values well (error <1%).Key words: Ganoderma lucidum, metal ions, biomass, polysaccharide, orthogonal projects

Crustal structure across the Dabie–Sulu orogenic belt revealed by seismic velocity profiles

The Tan-Lu fault (TLF) separates the Dabie and Sulu orogenic belts, well known for their ultra high pressure (UHP) metamorphic rocks in eastern China. We reinterpret one of the wide-angle seismic profiles traversing the TLF using traveltime tomography methods, and compare the results with the interpretation of three other seismic profiles across the TLF, to enable us to study the relationship of the five tectonic units comprising the North China plate (NCP), the Yangtze plate (YTZP), the TLF, the Dabie–Sulu orogenic belt (DSOB), and the ultra-high pressure metamorphic belt (UHPMB) that is exposed within the DSOB. The results demonstrate that there is strong lateral heterogeneity within the studied area. The TLF's penetrating depth deepens along a S–N direction. In the central section of the fault, the TLF can be traced to the middle crust but in the northern section it penetrates to the Moho. The average P-wave velocity in the UHPMB and DSOB is 0.1–0.4 km s-1 faster than that of the YTZP, NCP and TLF for upper crusts with depths 13 km. The bottom borders of the middle and lower crusts of the UHPMB and DSOB are apparently deeper than the other three tectonic units, and the Moho beneath UHPMB around Dabieshan may be deeper than 40 km. The general similarities of the crustal velocity structures between the Dabie and Sulu UHPMB may suggest a similar exhuming mechanism of UHP metamorphic rocks, before the large-scale TLF strike slip, driven by the subduction of the Yangtze block. The velocity gradient of the crust–mantle transition beneath the Sulu UHPMB implies the intrusion of basaltic melts from the upper mantle

Nerve growth factor/p75 neurotrophin receptor–mediated sensitization of rat sensory neurons depends on membrane cholesterol

Nerve growth factor (NGF) is an important mediator in the initiation of the inflammatory response and NGF via activation of the p75 neurotrophin receptor (p75(NTR)) and downstream sphingomyelin signaling leads to significant enhancement of the excitability of small-diameter sensory neurons. Because of the interaction between sphingomyelin and cholesterol in creating membrane liquid-ordered domains known as membrane or lipid rafts, we examined whether neuronal NGF-induced sensitization via p75(NTR) was dependent on the integrity of membrane rafts. Here, we demonstrate that the capacity of NGF to enhance the excitability of sensory neurons may result from the interaction of p75(NTR) with its downstream signaling partner(s) in membrane rafts. Two agents known to disrupt membrane rafts, edelfosine and methyl-β-cyclodextrin (MβCD), block the increase in excitability produced by NGF. In contrast, treatment with MβCD containing saturated amounts of cholesterol does not alter the capacity of NGF to augment excitability. In addition, adding back MβCD with cholesterol restored the NGF-induced sensitization in previously cholesterol-depleted neurons, suggesting that cholesterol and the structural integrity of rafts are key to promoting NGF-mediated sensitization. Using established protocols to isolate detergent-resistant membranes, both p75(NTR) and the neuronal membrane raft marker, flotillin, localize to raft fractions. These results suggest that downstream signaling partners interacting with p75(NTR) in sensory neurons are associated with membrane raft signaling platforms

Human cardiac Kv4.3 channels are regulated by protein tyrosine kinases

Poster presentationpublished_or_final_versionThe 15th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 64, abstract no. 11

A variational approach for dissipative quantum transport in a wide parameter space

published_or_final_versio

Mathematical Modelling and Experimental Evaluation of Electrostatic Sensor Arrays for the Flow Measurement of Fine Particles in a Square-shaped Pipe

Abstract—Square-shaped pneumatic conveying pipes are used in some industrial processes such as fuel injection systems in coal-fired power plants and circulating fluidized beds. However, little research has been conducted to characterise the gas–solid two-phase flow in a square-shaped pneumatic conveying pipe. This paper presents mathematical modelling and experimental assessment of novel non-restrictive electrostatic sensor arrays for the measurement of pulverised fuel flow in a square-shaped pipe. The sensor arrays consist of twelve pairs of strip-shaped electrodes, which are uniformly embedded in the four flat pipe walls. An analytical mathematical model of the sensor arrays is established and the induced charge and currents of different electrodes due to a point charge are then derived based on the model. Experimental tests were conducted on a 54 mm square-shaped pipe section of a pneumatic conveyor test rig under a range of flow conditions. The fuel velocity profile over the whole cross-section of the pipe is measured. Mathematical modelling and experimental results demonstrate that the proposed non-restrictive electrostatic sensor arrays are capable of characterising the local pulverised fuel flow in a square-shaped pneumatic conveying pipe. Index Terms—electrostatic sensor, square-shaped pipe, mathematical modelling, velocity profile, pulverised fuel

Managing Uncertain Complex Events in Web of Things Applications

A critical issue in the Web of Things (WoT) is the need to process and analyze the interactions of Web-interconnected real-world objects. Complex Event Processing (CEP) is a powerful technology for analyzing streams of information about real-time distributed events, coming from different sources, and for extracting conclusions from them. However, in many situations these events are not free from uncertainty, due to either unreliable data sources and networks, measurement uncertainty, or to the inability to determine whether an event has actually happened or not. This short research paper discusses how CEP systems can incorporate different kinds of uncertainty, both in the events and in the rules. A case study is used to validate the proposal, and we discuss the benefits and limitations of this CEP extension.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Stimulation of artemisinin biosynthesis in Artemisia annua hairy roots by oligogalacturonides

The different fractions of oligogalacturonides (OGA) from polygalacturonic acid by pectinase hydrolysate have been partially purified using column chromatography of Sephadex G-10. The isolated fraction OGA2 (degree of polymerization, DP = 4.57) was found to stimulate the accumulation ofartemisinin in Artemisia annua hairy roots. When hairy roots of 16-day old cultures were exposed to the OGA elicitor (60 g/mL) for 4 days, the maximum production of artemisinin reached 11.3 mg/L, a 55.2% increase over the control. OGA could induce H2O2 production in hairy root culture as one of early defense events. Moreover, the OGA-induced reactive oxygen species (ROS) were involved in stimulating the artemisinin biosynthesis in the hairy roots. This is the first report on the stimulation of artemisinin production in hairy roots by an oligogalacturonide elicitor